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</div> <div class="control"> <button class="button is-small is-link">Go</button> </div> </div> </form> </div> </div> <ol class="breathe-horizontal" start="1"> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2502.11936">arXiv:2502.11936</a> <span> [<a href="https://arxiv.org/pdf/2502.11936">pdf</a>, <a href="https://arxiv.org/format/2502.11936">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1007/s00348-011-1073-7">10.1007/s00348-011-1073-7 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Regimes of spray formation in gas-centered swirl coaxial atomizers </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Sivakumar%2C+D">Deivandren Sivakumar</a>, <a href="/search/physics?searchtype=author&query=Kulkarni%2C+V">Varun Kulkarni</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2502.11936v1-abstract-short" style="display: inline;"> Spray formation in ambient atmosphere from gas-centered swirl coaxial atomizers is described by carrying out experiments in a spray test facility. The atomizer discharges a circular air jet and an axisymmetric swirling water sheet from its coaxially arranged inner and outer orifices. A high-speed digital imaging system along with a backlight illumination arrangement is employed to record the detai… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2502.11936v1-abstract-full').style.display = 'inline'; document.getElementById('2502.11936v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2502.11936v1-abstract-full" style="display: none;"> Spray formation in ambient atmosphere from gas-centered swirl coaxial atomizers is described by carrying out experiments in a spray test facility. The atomizer discharges a circular air jet and an axisymmetric swirling water sheet from its coaxially arranged inner and outer orifices. A high-speed digital imaging system along with a backlight illumination arrangement is employed to record the details of liquid sheet breakup and spray development. Spray regimes exhibiting different sheet breakup mechanisms are identified and their characteristic features presented. The identified spray regimes are wave-assisted sheet breakup, perforated sheet breakup, segmented sheet breakup, and pulsation spray regime. In the regime of wave-assisted sheet breakup, the sheet breakup shows features similar to the breakup of two-dimensional planar air-blasted liquid sheets. At high air-to-liquid momentum ratios, the interaction process between the axisymmetric swirling liquid sheet and the circular air jet develops spray processes which are more specific to the atomizer studied here. The spray exhibits a periodic ejection of liquid masses whose features are dominantly controlled by the central air jet. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2502.11936v1-abstract-full').style.display = 'none'; document.getElementById('2502.11936v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 17 February, 2025; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2025. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">9 pages, 12 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Exp. Fluids 51 (2011) 587-596 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2412.13293">arXiv:2412.13293</a> <span> [<a href="https://arxiv.org/pdf/2412.13293">pdf</a>, <a href="https://arxiv.org/ps/2412.13293">ps</a>, <a href="https://arxiv.org/format/2412.13293">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1016/j.ijmultiphaseflow.2024.105076">10.1016/j.ijmultiphaseflow.2024.105076 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Spatial evolution of droplet size and velocity characteristics in a swirl spray </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Vankeswaram%2C+S+K">S. K. Vankeswaram</a>, <a href="/search/physics?searchtype=author&query=Kulkarni%2C+V">V. Kulkarni</a>, <a href="/search/physics?searchtype=author&query=Deivandren%2C+S">S. Deivandren</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2412.13293v1-abstract-short" style="display: inline;"> Spray drop size distribution generated by atomization of fuel influences several facets of a combustion process such as, fuel-air mixing, reaction kinetics and thrust generation. In a typical spray, the drop size distribution evolves spatially, varying significantly between the near and far regions of the spray. Studies so far have focused on either one of these regions and are unclear on the exac… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.13293v1-abstract-full').style.display = 'inline'; document.getElementById('2412.13293v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2412.13293v1-abstract-full" style="display: none;"> Spray drop size distribution generated by atomization of fuel influences several facets of a combustion process such as, fuel-air mixing, reaction kinetics and thrust generation. In a typical spray, the drop size distribution evolves spatially, varying significantly between the near and far regions of the spray. Studies so far have focused on either one of these regions and are unclear on the exact axial location of transition. In this work, we address this crucial gap by considering a swirl atomizer and measuring the droplet characteristics for different liquid flow conditions of the ensuing spray at various radial and axial locations. Our results reveal an axial variation in the scaled radial droplet velocity profiles, not followed by the radial drop size profiles, from which we demarcate the near region as the zone which extends to 2.0 to 2.5 times film breakup length. Beyond this distance, the drop size characteristics are influenced by external factors such as airflow and identified as the far region. Further, we locate the point of origin of the droplet high-velocity stream along the spray centreline to the end of film breakup of the spray. We also find that the global probability density functions for droplet size and velocity which show a bimodal behavior in the near-region and unimodal in the far-region being well represented by the double Gaussian and Gamma distributions, respectively. We further quantify our results by number and volume flux distributions, global mean drop sizes, drop size ($D_d$) axial velocity ($U_a$) correlations, axial velocity based on drop size classification and turbulent kinetic energy (TKE) to reveal the effect of drop inertia and air flow in determining the statistics in both the near and far regions. We anticipate the findings of this work will guide future investigations on combustion processes and combustor design based on spray characteristics. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.13293v1-abstract-full').style.display = 'none'; document.getElementById('2412.13293v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 17 December, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.16961">arXiv:2410.16961</a> <span> [<a href="https://arxiv.org/pdf/2410.16961">pdf</a>, <a href="https://arxiv.org/format/2410.16961">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Soft Condensed Matter">cond-mat.soft</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1063/5.0216820">10.1063/5.0216820 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Modulating outcomes of oil drops bursting at a water-air interface </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Kulkarni%2C+V">Varun Kulkarni</a>, <a href="/search/physics?searchtype=author&query=Tamvada%2C+S">Suhas Tamvada</a>, <a href="/search/physics?searchtype=author&query=Lolla%2C+Y+V">Yashasvi Venkata Lolla</a>, <a href="/search/physics?searchtype=author&query=Anand%2C+S">Sushant Anand</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2410.16961v1-abstract-short" style="display: inline;"> Recent studies have shown that capillary waves generated by bursting of an oil drop at the water-air interface produces a daughter droplet inside the bath while part of it floats above it. Successive bursting events produce next generations of daughter droplets, gradually diminishing in size until the entire volume of oil rests atop the water-air interface. In this work, we demonstrate two differe… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.16961v1-abstract-full').style.display = 'inline'; document.getElementById('2410.16961v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.16961v1-abstract-full" style="display: none;"> Recent studies have shown that capillary waves generated by bursting of an oil drop at the water-air interface produces a daughter droplet inside the bath while part of it floats above it. Successive bursting events produce next generations of daughter droplets, gradually diminishing in size until the entire volume of oil rests atop the water-air interface. In this work, we demonstrate two different ways to modulate this process by modifying the constitution of the drop. Firstly, we introduce hydrophilic clay particles inside the parent oil drop and show that it arrests the cascade of daughter droplet generation preventing it from floating over the water-air interface. Secondly, we show that bursting behavior can be modified by a compound water-oil-air interface made of a film of oil with finite thickness and design a regime map which displays each of these outcomes. We underpin both of these demonstrations by theoretical arguments providing criteria to predict outcomes resulting therein. Lastly, all our scenarios have a direct relation to control of oil-water separation and stability of emulsified solutions in a wide variety of applications which include drug delivery, enhanced oil recovery, oil spills and food processing where a dispersed oil phase tries to separate from a continuous phase. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.16961v1-abstract-full').style.display = 'none'; document.getElementById('2410.16961v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 22 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Appl. Phys. Lett. 125.14 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2405.08264">arXiv:2405.08264</a> <span> [<a href="https://arxiv.org/pdf/2405.08264">pdf</a>, <a href="https://arxiv.org/format/2405.08264">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1115/1.4000737">10.1115/1.4000737 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Liquid Sheet Breakup in Gas-Centered Swirl Coaxial Atomizers </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Kulkarni%2C+V">V. Kulkarni</a>, <a href="/search/physics?searchtype=author&query=Sivakumar%2C+D">D. Sivakumar</a>, <a href="/search/physics?searchtype=author&query=Oommen%2C+C">C. Oommen</a>, <a href="/search/physics?searchtype=author&query=Tharakan%2C+T+J">T. J. Tharakan</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2405.08264v1-abstract-short" style="display: inline;"> The study deals with the breakup behavior of swirling liquid sheets discharging from gas-centered swirl coaxial atomizers with attention focused toward the understanding of the role of central gas jet on the liquid sheet breakup. Cold flow experiments on the liquid sheet breakup were carried out by employing custom fabricated gas-centered swirl coaxial atomizers using water and air as experimental… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.08264v1-abstract-full').style.display = 'inline'; document.getElementById('2405.08264v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.08264v1-abstract-full" style="display: none;"> The study deals with the breakup behavior of swirling liquid sheets discharging from gas-centered swirl coaxial atomizers with attention focused toward the understanding of the role of central gas jet on the liquid sheet breakup. Cold flow experiments on the liquid sheet breakup were carried out by employing custom fabricated gas-centered swirl coaxial atomizers using water and air as experimental fluids. Photographic techniques were employed to capture the flow behavior of liquid sheets at different flow conditions. Quantitative variation on the breakup length of the liquid sheet and spray width were obtained from the measurements deduced from the images of liquid sheets. The sheet breakup process is significantly influenced by the central air jet. It is observed that low inertia liquid sheets are more vulnerable to the presence of the central air jet and develop shorter breakup lengths at smaller values of the air jet Reynolds number $Re_g$. High inertia liquid sheets ignore the presence of the central air jet at smaller values of $Re_g$ and eventually develop shorter breakup lengths at higher values of $Re_g$. The experimental evidences suggest that the central air jet causes corrugations on the liquid sheet surface, which may be promoting the production of thick liquid ligaments from the sheet surface. The level of surface corrugations on the liquid sheet increases with increasing $Re_g$. Qualitative analysis of experimental observations reveals that the entrainment process of air established between the inner surface of the liquid sheet and the central air jet is the primary trigger for the sheet breakup. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.08264v1-abstract-full').style.display = 'none'; document.getElementById('2405.08264v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 13 May, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> J. Fluids Eng. 132 (2010) 011303 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2405.08259">arXiv:2405.08259</a> <span> [<a href="https://arxiv.org/pdf/2405.08259">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1007/s00348-015-1917-7">10.1007/s00348-015-1917-7 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> An experimental and theoretical investigation of spray characteristics of impinging jets in impact wave regime </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Rodrigues%2C+N+S">Neil S. Rodrigues</a>, <a href="/search/physics?searchtype=author&query=Kulkarni%2C+V">Varun Kulkarni</a>, <a href="/search/physics?searchtype=author&query=Gao%2C+J">Jian Gao</a>, <a href="/search/physics?searchtype=author&query=Chen%2C+J">Jun Chen</a>, <a href="/search/physics?searchtype=author&query=Sojka%2C+P+E">Paul E. Sojka</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2405.08259v1-abstract-short" style="display: inline;"> The current study focuses on experimentally and theoretically improving the characterization of the drop size and drop velocity for like-on-like doublet impinging jets. The experimental measurements were made using phase Doppler anemometry (PDA) at jet Weber numbers We j corresponding to the impact wave regime of impinging jet atomization. A more suitable dynamic range was used for PDA measurement… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.08259v1-abstract-full').style.display = 'inline'; document.getElementById('2405.08259v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.08259v1-abstract-full" style="display: none;"> The current study focuses on experimentally and theoretically improving the characterization of the drop size and drop velocity for like-on-like doublet impinging jets. The experimental measurements were made using phase Doppler anemometry (PDA) at jet Weber numbers We j corresponding to the impact wave regime of impinging jet atomization. A more suitable dynamic range was used for PDA measurements compared to the literature, resulting in more accurate experimental measurements for drop diameters and velocities. There is some disagreement in the literature regarding the ability of linear stability analysis to accurately predict drop diameters in the impact wave regime. This work seeks to provide some clarity. It was discovered that the assumed uniform jet velocity profile was a contributing factor for deviation between diameter predictions based on models in the literature and experimental measurements. Analytical expressions that depend on parameters based on the assumed jet velocity profile are presented in this work. Predictions based on the parabolic and 1/7th power law turbulent profiles were considered and show better agreement with the experimental measurements compared to predictions based on the previous models. Experimental mean drop velocity measurements were compared with predictions from a force balance analysis, and it was observed that the assumed jet velocity profile also influences the predicted velocities, with the turbulent profile agreeing best with the experimental mean velocity. It is concluded that the assumed jet velocity profile has a predominant effect on drop diameter and velocity predictions. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.08259v1-abstract-full').style.display = 'none'; document.getElementById('2405.08259v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 13 May, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Exp. Fluids 56 (2015) 1-13 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2308.04652">arXiv:2308.04652</a> <span> [<a href="https://arxiv.org/pdf/2308.04652">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1016/j.jaerosci.2023.106245">10.1016/j.jaerosci.2023.106245 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Drop size characteristics of sprays emanating from circular and non-circular orifices in the atomization regime </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Rajesh%2C+K+R">K. R. Rajesh</a>, <a href="/search/physics?searchtype=author&query=Kulkarni%2C+V">V. Kulkarni</a>, <a href="/search/physics?searchtype=author&query=Vankeswaram%2C+S">S. Vankeswaram</a>, <a href="/search/physics?searchtype=author&query=Sakthikumar%2C+R">R. Sakthikumar</a>, <a href="/search/physics?searchtype=author&query=Deivandren%2C+S">S. Deivandren</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2308.04652v1-abstract-short" style="display: inline;"> Traditionally, circular orifices have been used for generating aerosols, however in recent times non-circular orifices are being considered due to their superior atomization and mixing features. In this work, we experimentally investigate spray morphology and drop size characteristics of kerosene (Jet A-1) jets issuing from three non-circular orifices geometries (elliptic, triangular and, square)… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.04652v1-abstract-full').style.display = 'inline'; document.getElementById('2308.04652v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2308.04652v1-abstract-full" style="display: none;"> Traditionally, circular orifices have been used for generating aerosols, however in recent times non-circular orifices are being considered due to their superior atomization and mixing features. In this work, we experimentally investigate spray morphology and drop size characteristics of kerosene (Jet A-1) jets issuing from three non-circular orifices geometries (elliptic, triangular and, square) and one circular orifice with the same exit cross sectional area. Our results show an unexpected and yet unreported coarsening of atomization for non-circular orifice jets quantified by an increase in the Sauter Mean Diameter (SMD) at all tested exit velocities represented by the liquid Weber number, $We_l$. We attribute this to two distinct spray morphologies: filament and core breakup which generate large size liquid structures identified as filaments and ligaments, noticeable in non-circular orifices jets compared to circular orifice jets. On exploring this further by undertaking an examination of the drop size volume probability distribution at lower $We_l$ corresponding to the location marking the end of primary breakup we see a bimodality due to a dominant distribution of fragments of small and larger sizes owing to the spray morphology. At higher $We_l$ and larger distances from the injector exit we observe the bimodality converts to a unimodal distribution for all orifice jets with a single peak situated at lower drop diameters. Filament breakup is reasoned to be the cause of higher number of smaller drop sizes in triangular sprays among all non-circular orifice jets while thinner filaments in circular orifice sprays lead to smaller drop sizes compared to their triangular counterparts showing the same breakup morphology. We expect our results to help applications as diverse as engine fuel combustion, pharmaceutical sprays and CO$_2$ capture by NaOH sprays. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.04652v1-abstract-full').style.display = 'none'; document.getElementById('2308.04652v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 8 August, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2307.16241">arXiv:2307.16241</a> <span> [<a href="https://arxiv.org/pdf/2307.16241">pdf</a>, <a href="https://arxiv.org/format/2307.16241">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1063/5.0152096">10.1063/5.0152096 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> On interdependence of instabilities and average drop sizes in bag breakup </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Kulkarni%2C+V">Varun Kulkarni</a>, <a href="/search/physics?searchtype=author&query=Shirdade%2C+N">Nikhil Shirdade</a>, <a href="/search/physics?searchtype=author&query=Rodrigues%2C+N">Neil Rodrigues</a>, <a href="/search/physics?searchtype=author&query=Radhakrishna%2C+V">Vishnu Radhakrishna</a>, <a href="/search/physics?searchtype=author&query=Sojka%2C+P+E">Paul E. Sojka</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2307.16241v2-abstract-short" style="display: inline;"> A drop exposed to cross flow of air experiences sudden accelerations which deform it rapidly ultimately proceeding to disintegrate it into smaller fragments. In this work, we examine the breakup of a drop as a bag film with a bounding rim resulting from acceleration induced Rayleigh-Taylor instabilities and characterized through the Weber number, \textit{We}, representative of the competition betw… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.16241v2-abstract-full').style.display = 'inline'; document.getElementById('2307.16241v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2307.16241v2-abstract-full" style="display: none;"> A drop exposed to cross flow of air experiences sudden accelerations which deform it rapidly ultimately proceeding to disintegrate it into smaller fragments. In this work, we examine the breakup of a drop as a bag film with a bounding rim resulting from acceleration induced Rayleigh-Taylor instabilities and characterized through the Weber number, \textit{We}, representative of the competition between the disruptive aerodynamic force imparting acceleration and the restorative surface tension force. Our analysis reveals a previously overlooked parabolic dependence ($\sim We^2$) of the combination of dimensionless instability wavelengths $({\bar位}_{bag}^2/ {\bar位}_{rim}^4 {\bar位}_{film})$ developing on different segments of the deforming drop. Further, we extend these findings to deduce the dependence of the average dimensionless drop sizes for the rim, $\langle{\bar{D}}_{rim}\rangle$ and bag film, $\langle{\bar{D}}_{film}\rangle$ individually, on $We$ and see them to decrease linearly for the rim ($\sim We^{-1}$) and quadratically for the bag film ($\sim We^{-2}$). The reported work is expected to have far-reaching implications as it provides unique insights on destabilization and disintegration mechanisms based on theoretical scaling arguments involving the commonly encountered canonical geometries of a toroidal rim and a curved liquid film. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.16241v2-abstract-full').style.display = 'none'; document.getElementById('2307.16241v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 25 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 30 July, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2307.11721">arXiv:2307.11721</a> <span> [<a href="https://arxiv.org/pdf/2307.11721">pdf</a>, <a href="https://arxiv.org/format/2307.11721">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Astrophysics of Galaxies">astro-ph.GA</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Applied Physics">physics.app-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1093/mnras/stad2134">10.1093/mnras/stad2134 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> MUSE-ALMA Haloes IX: Morphologies and Stellar Properties of Gas-rich Galaxies </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Karki%2C+A">Arjun Karki</a>, <a href="/search/physics?searchtype=author&query=Kulkarni%2C+V+P">Varsha P. Kulkarni</a>, <a href="/search/physics?searchtype=author&query=Weng%2C+S">Simon Weng</a>, <a href="/search/physics?searchtype=author&query=P%C3%A9roux%2C+C">C茅line P茅roux</a>, <a href="/search/physics?searchtype=author&query=Augustin%2C+R">Ramona Augustin</a>, <a href="/search/physics?searchtype=author&query=Hayes%2C+M">Matthew Hayes</a>, <a href="/search/physics?searchtype=author&query=Ayromlou%2C+M">Mohammadreza Ayromlou</a>, <a href="/search/physics?searchtype=author&query=Kacprzak%2C+G+G">Glenn G. Kacprzak</a>, <a href="/search/physics?searchtype=author&query=Howk%2C+J+C">J. Christopher Howk</a>, <a href="/search/physics?searchtype=author&query=Szakacs%2C+R">Roland Szakacs</a>, <a href="/search/physics?searchtype=author&query=Klitsch%2C+A">Anne Klitsch</a>, <a href="/search/physics?searchtype=author&query=Hamanowicz%2C+A">Aleksandra Hamanowicz</a>, <a href="/search/physics?searchtype=author&query=Fresco%2C+A">Alejandra Fresco</a>, <a href="/search/physics?searchtype=author&query=Zwaan%2C+M+A">Martin A. Zwaan</a>, <a href="/search/physics?searchtype=author&query=Biggs%2C+A+D">Andrew D. Biggs</a>, <a href="/search/physics?searchtype=author&query=Fox%2C+A+J">Andrew J. Fox</a>, <a href="/search/physics?searchtype=author&query=Kassin%2C+S">Susan Kassin</a>, <a href="/search/physics?searchtype=author&query=Kuntschner%2C+H">Harald Kuntschner</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2307.11721v1-abstract-short" style="display: inline;"> Understanding how galaxies interact with the circumgalactic medium (CGM) requires determining how galaxies morphological and stellar properties correlate with their CGM properties. We report an analysis of 66 well-imaged galaxies detected in HST and VLT MUSE observations and determined to be within $\pm$500 km s$^{-1}$ of the redshifts of strong intervening quasar absorbers at… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.11721v1-abstract-full').style.display = 'inline'; document.getElementById('2307.11721v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2307.11721v1-abstract-full" style="display: none;"> Understanding how galaxies interact with the circumgalactic medium (CGM) requires determining how galaxies morphological and stellar properties correlate with their CGM properties. We report an analysis of 66 well-imaged galaxies detected in HST and VLT MUSE observations and determined to be within $\pm$500 km s$^{-1}$ of the redshifts of strong intervening quasar absorbers at $0.2 \lesssim z \lesssim 1.4$ with H I column densities $N_{\rm H I}$ $>$ $10^{18}$ $\rm cm^{-2}$. We present the geometrical properties (S茅rsic indices, effective radii, axis ratios, and position angles) of these galaxies determined using GALFIT. Using these properties along with star formation rates (SFRs, estimated using the H$伪$ or [O II] luminosity) and stellar masses ($M_{*}$ estimated from spectral energy distribution fits), we examine correlations among various stellar and CGM properties. Our main findings are as follows: (1) SFR correlates well with $M_{*}$, and most absorption-selected galaxies are consistent with the star formation main sequence (SFMS) of the global population. (2) More massive absorber counterparts are more centrally concentrated and are larger in size. (3) Galaxy sizes and normalized impact parameters correlate negatively with $N_{\rm H I}$, consistent with higher $N_{\rm H I}$ absorption arising in smaller galaxies, and closer to galaxy centers. (4) Absorption and emission metallicities correlate with $M_{*}$ and sSFR, implying metal-poor absorbers arise in galaxies with low past star formation and faster current gas consumption rates. (5) SFR surface densities of absorption-selected galaxies are higher than predicted by the Kennicutt-Schmidt relation for local galaxies, suggesting a higher star formation efficiency in the absorption-selected galaxies. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.11721v1-abstract-full').style.display = 'none'; document.getElementById('2307.11721v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 21 July, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in MNRAS, 25 pages, 19 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">MSC Class:</span> newtxmath </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2306.10421">arXiv:2306.10421</a> <span> [<a href="https://arxiv.org/pdf/2306.10421">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mathematical Physics">math-ph</span> </div> </div> <p class="title is-5 mathjax"> An analytical and experimental study of secondary atomization for vibrational and bag breakup modes </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Kulkarni%2C+V">Varun Kulkarni</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2306.10421v1-abstract-short" style="display: inline;"> Bag breakup of drops has been a subject of interest for almost over a century. Several issues such as theoretical estimation of the regime boundary marking the onset of such breakup, bag growth rates, drop size distribution, and the effect of Weber number, $We$, and Ohnesorge number, $Oh$, on these quantities remains unaddressed. The current study aims to clarify aspects of the atomization process… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.10421v1-abstract-full').style.display = 'inline'; document.getElementById('2306.10421v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2306.10421v1-abstract-full" style="display: none;"> Bag breakup of drops has been a subject of interest for almost over a century. Several issues such as theoretical estimation of the regime boundary marking the onset of such breakup, bag growth rates, drop size distribution, and the effect of Weber number, $We$, and Ohnesorge number, $Oh$, on these quantities remains unaddressed. The current study aims to clarify aspects of the atomization process through experiments and theory. We examine bag breakup of a single drop of various inviscid and low viscosity fluids as it deforms in the presence of a continuous horizontal air jet. The We boundary at which bag breakup begins is theoretically determined and the expression obtained, $We = 12(1 + \frac{2}{3} Oh^2)$, is found to match well with existing experimental data. An exponential growth in the radial extent of the deformed drop and the streamline dimension of the bag is predicted by the theoretical model and confirmed by experimental findings. These quantities are observed to strongly depend on $We$. However, their dependence on $Oh$ is weak for the range of $Oh$ considered in this study. Subsequent to drop deformation, bag formation and expansion is the bursting process. This is marked by the disintegration of the bag owing to instability of the Rayleigh-Taylor type, followed by collapse of the liquid rim bounding this bag by Plateau-Rayleigh instability. The sizes of the drops thus produced are measured using Phase Doppler Anemometry (PDA) which is in contrast to shadowgraphs used in earlier studies. A discernible shift in the peak of the drop size distribution for viscous drops is seen which indicates a preponderance of drops of higher diameters vis-脿-vis fragment size distribution for inviscid drops. Furthermore, an estimate of the Sauter mean diameter ($D_{32}$) is presented which is somewhat lower than earlier predictions. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.10421v1-abstract-full').style.display = 'none'; document.getElementById('2306.10421v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 17 June, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">PhD Dissertation. Purdue University (2013)</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2304.12104">arXiv:2304.12104</a> <span> [<a href="https://arxiv.org/pdf/2304.12104">pdf</a>, <a href="https://arxiv.org/format/2304.12104">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Soft Condensed Matter">cond-mat.soft</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Applied Physics">physics.app-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1122/8.0000679">10.1122/8.0000679 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Data-driven rheological characterization of stress buildup and relaxation in thermal greases </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Nagrani%2C+P+P">Pranay P. Nagrani</a>, <a href="/search/physics?searchtype=author&query=Kulkarni%2C+R+V">Ritwik V. Kulkarni</a>, <a href="/search/physics?searchtype=author&query=Kelkar%2C+P+U">Parth U. Kelkar</a>, <a href="/search/physics?searchtype=author&query=Corder%2C+R+D">Ria D. Corder</a>, <a href="/search/physics?searchtype=author&query=Erk%2C+K+A">Kendra A. Erk</a>, <a href="/search/physics?searchtype=author&query=Marconnet%2C+A+M">Amy M. Marconnet</a>, <a href="/search/physics?searchtype=author&query=Christov%2C+I+C">Ivan C. Christov</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2304.12104v2-abstract-short" style="display: inline;"> Thermal greases, often used as thermal interface materials, are complex paste-like mixtures composed of a base polymer in which dense metallic (or ceramic) filler particles are dispersed to improve the heat transfer properties of the material. They have complex rheological properties that impact the performance of the thermal interface material over its lifetime. We perform rheological experiments… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.12104v2-abstract-full').style.display = 'inline'; document.getElementById('2304.12104v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2304.12104v2-abstract-full" style="display: none;"> Thermal greases, often used as thermal interface materials, are complex paste-like mixtures composed of a base polymer in which dense metallic (or ceramic) filler particles are dispersed to improve the heat transfer properties of the material. They have complex rheological properties that impact the performance of the thermal interface material over its lifetime. We perform rheological experiments on thermal greases and observe both stress relaxation and stress buildup regimes. This time-dependent rheological behavior of such complex fluid-like materials is not captured by steady shear-thinning models often used to describe these materials. We find that thixo-elasto-visco-plastic (TEVP) and nonlinear-elasto-visco-plastic (NEVP) constitutive models characterize the observed stress relaxation and buildup regimes respectively. Specifically, we use the models within a data-driven approach based on physics-informed neural networks (PINNs). PINNs are used to solve the inverse problem of determining the rheological model parameters from the dynamic response in experiments. This training data is generated by startup flow experiments at different (constant) shear rates using a shear rheometer. We validate the ``learned'' models by comparing their predicted shear stress evolution to experiments under shear rates not used in the training datasets. We further validate the learned TEVP model by solving a forward problem numerically to determine the shear stress evolution for an input step-strain profile. Meanwhile, the NEVP model is further validated by comparison to a steady Herschel--Bulkley fit of the material's flow curve. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.12104v2-abstract-full').style.display = 'none'; document.getElementById('2304.12104v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 22 September, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 24 April, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">13 pages, 10 figures; v2 included new validation appendices; to appear in J. Rheol</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> J. Rheol. 67 (2023) 1129--1140 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2208.03801">arXiv:2208.03801</a> <span> [<a href="https://arxiv.org/pdf/2208.03801">pdf</a>, <a href="https://arxiv.org/format/2208.03801">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevFluids.9.053604">10.1103/PhysRevFluids.9.053604 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Increased solidification delays fragmentation and suppresses rebound of impacting drops </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Kulkarni%2C+V">Varun Kulkarni</a>, <a href="/search/physics?searchtype=author&query=Tamvada%2C+S">Suhas Tamvada</a>, <a href="/search/physics?searchtype=author&query=Shirdade%2C+N">Nikhil Shirdade</a>, <a href="/search/physics?searchtype=author&query=Saneie%2C+N">Navid Saneie</a>, <a href="/search/physics?searchtype=author&query=Lolla%2C+V+Y">Venkata Yashasvi Lolla</a>, <a href="/search/physics?searchtype=author&query=Batheyrameshbapu%2C+V">Vijayprithiv Batheyrameshbapu</a>, <a href="/search/physics?searchtype=author&query=Anand%2C+S">Sushant Anand</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2208.03801v6-abstract-short" style="display: inline;"> The splat formed after drop impact on supercooled solid surfaces sticks to it. On the contrary, a sublimating supercooled surface such as dry ice inhibits pinning and therefore efficiently rebounds drops made of a variety of liquids. While rebound is expected at lower impact velocities on dry ice, at higher impact velocities the drop fragments leaving behind a trail of smaller droplets. However, i… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2208.03801v6-abstract-full').style.display = 'inline'; document.getElementById('2208.03801v6-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2208.03801v6-abstract-full" style="display: none;"> The splat formed after drop impact on supercooled solid surfaces sticks to it. On the contrary, a sublimating supercooled surface such as dry ice inhibits pinning and therefore efficiently rebounds drops made of a variety of liquids. While rebound is expected at lower impact velocities on dry ice, at higher impact velocities the drop fragments leaving behind a trail of smaller droplets. However, it is not known whether rebound can be entirely suppressed or fragmentation be controlled on such surfaces and if it depends on the extent of solidification inside the drop. In this work, we report on the role played by solidification within drops in modifying the outcomes of their impact on the supercooled ultra-low adhesive surface of sublimating dry ice. We show that the solidification thickness depends on the impact velocity and is the primary driver in suppression of rebound and also promotes a delay in fragmentation. Our findings imply that sublimating supercooled surfaces can present a broad spectrum of outcomes from complete bouncing to no-rebound which are not seen in drop impacts on supercooled superhydrophobic surfaces. We attribute this to thermo-elastocapillarity which considers bending of the solidified layer and is used to demarcate regime boundaries and determine the coefficient of restitution during rebound. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2208.03801v6-abstract-full').style.display = 'none'; document.getElementById('2208.03801v6-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 25 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 7 August, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Fluids 9 (2024) 053604-22 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2204.06036">arXiv:2204.06036</a> <span> [<a href="https://arxiv.org/pdf/2204.06036">pdf</a>, <a href="https://arxiv.org/format/2204.06036">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1063/1.4887817">10.1063/1.4887817 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Bag breakup of low viscosity drops in the presence of a continuous air jet </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Kulkarni%2C+V">Varun Kulkarni</a>, <a href="/search/physics?searchtype=author&query=Sojka%2C+P+E">Paul E. Sojka</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2204.06036v4-abstract-short" style="display: inline;"> This work examines the breakup of a single drop of various low viscosity fluids as it deforms in the presence of continuous horizontal air jet. Such a fragmentation typically occurs after the bulk liquid has disintegrated upon exiting the atomizer and is in the form of an ensemble of drops which undergo further breakup. The drop deformation and its eventual disintegration is important in evaluatin… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.06036v4-abstract-full').style.display = 'inline'; document.getElementById('2204.06036v4-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2204.06036v4-abstract-full" style="display: none;"> This work examines the breakup of a single drop of various low viscosity fluids as it deforms in the presence of continuous horizontal air jet. Such a fragmentation typically occurs after the bulk liquid has disintegrated upon exiting the atomizer and is in the form of an ensemble of drops which undergo further breakup. The drop deformation and its eventual disintegration is important in evaluating the efficacy of a particular industrial process, be it combustion in automobile engines or pesticide spraying in agricultural applications. The interplay between competing influences of surface tension and aerodynamic disruptive forces is represented by the Weber number, $We$, and Ohnesorge number, $Oh$, and used to describe the breakup morphology. The breakup pattern considered in our study corresponds to that of a bag attached to a toroidal ring which occurs from $12 < We < 16$. We aim to address several issues connected with this breakup process and their dependence on $We$ and $Oh$ which have been hitherto unexplored. The $We$ boundary at which breakup begins is theoretically determined and the expression obtained, $We = 12(1 + 2/3Oh^2)$, is found to match well with experimental data available in literature. An exponential growth in the radial extent of the deformed drop and the streamline dimension of the bag is predicted by a theoretical model and confirmed by experimental findings. These quantities are observed to strongly depend on $We$. However, their dependence on $Oh$ is weak. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.06036v4-abstract-full').style.display = 'none'; document.getElementById('2204.06036v4-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 29 January, 2025; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 12 April, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Physics of Fluids 26.7 (2014): 072103 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2204.04804">arXiv:2204.04804</a> <span> [<a href="https://arxiv.org/pdf/2204.04804">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> </div> </div> <p class="title is-5 mathjax"> Bursting Drops </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Kulkarni%2C+V">Varun Kulkarni</a>, <a href="/search/physics?searchtype=author&query=Lolla%2C+V+Y">Venkata Yashasvi Lolla</a>, <a href="/search/physics?searchtype=author&query=Tamvada%2C+S">Suhas Tamvada</a>, <a href="/search/physics?searchtype=author&query=Anand%2C+S">Sushant Anand</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2204.04804v3-abstract-short" style="display: inline;"> For decades, researchers worldwide have investigated phenomena related to natural, artificial oil leakages such as oil drop formation within water bodies, their rise, and oil slick evolution after they breach the water-air interface. Despite this, the event leading to slick formation -the bursting of oil drops at the liquid-air interface has remained unnoticed thus far. In this work, we investigat… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.04804v3-abstract-full').style.display = 'inline'; document.getElementById('2204.04804v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2204.04804v3-abstract-full" style="display: none;"> For decades, researchers worldwide have investigated phenomena related to natural, artificial oil leakages such as oil drop formation within water bodies, their rise, and oil slick evolution after they breach the water-air interface. Despite this, the event leading to slick formation -the bursting of oil drops at the liquid-air interface has remained unnoticed thus far. In this work, we investigate this and report a counterintuitive jetting reversal that releases a daughter oil droplet inside the bulk as opposed to the upwards shooting jets observed in bursting air bubbles. We show that the daughter droplet size thus produced can be correlated to the bulk liquid properties and that its formation can be suppressed by increasing the bulk viscosity or by the addition of microparticles. We further demonstrate the significance of our results by synthesizing colloidal pickered droplets and show applications of bursting compound drops in double emulsions and studies on raindrop impact on a slick. These results could be immensely transformative for diverse areas, including climatology, oceanic, atmospheric sciences, colloidal synthesis and drug delivery. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.04804v3-abstract-full').style.display = 'none'; document.getElementById('2204.04804v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 28 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 10 April, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2022. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2204.04122">arXiv:2204.04122</a> <span> [<a href="https://arxiv.org/pdf/2204.04122">pdf</a>, <a href="https://arxiv.org/format/2204.04122">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Other Condensed Matter">cond-mat.other</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Applied Physics">physics.app-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1063/5.0132208">10.1063/5.0132208 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Calculation of tunneling current across Trapezoidal potential barrier in a Scanning Tunneling Microscope </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Dessai%2C+M">Malati Dessai</a>, <a href="/search/physics?searchtype=author&query=Kulkarni%2C+A+V">Arun V. Kulkarni</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2204.04122v2-abstract-short" style="display: inline;"> The Planar Model of the Electrode-Vacuum-Electrode configuration for STM in which electrode surfaces are assumed to be infinite parallel planes, with atomic size separation and vacuum between them, is used to calculate tunneling current densities for both low and high bias voltages. Non WKB, Airy function solutions for the Schr枚dinger Equation for the trapezoidal barrier in the tunneling region ar… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.04122v2-abstract-full').style.display = 'inline'; document.getElementById('2204.04122v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2204.04122v2-abstract-full" style="display: none;"> The Planar Model of the Electrode-Vacuum-Electrode configuration for STM in which electrode surfaces are assumed to be infinite parallel planes, with atomic size separation and vacuum between them, is used to calculate tunneling current densities for both low and high bias voltages. Non WKB, Airy function solutions for the Schr枚dinger Equation for the trapezoidal barrier in the tunneling region are used to calculate the tunneling probability. Temperature dependent Fermi Factors for each electrode are introduced and the calculation involves integration over the electron energies. In order to convert the current densities obtained in the planar model to tunneling currents the tip and sample surfaces are modelled as confocal hyperboloids, and the tip sample distance is replaced by the length of the line of force (field line). The current is found by integrating the current density over a finite area of the tip. The calculated tunnel currents for a few electrode pairs at room temperature are plotted for several values of bias voltage, tip sample distances, and tip radii of curvature. Pauli Effects are studied as a function of bias voltage and tip-sample distance. Some estimate of lateral resolution and its dependence on bias voltage and tip radius is also presented. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.04122v2-abstract-full').style.display = 'none'; document.getElementById('2204.04122v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 4 October, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 8 April, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">15 pages,21 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2112.00870">arXiv:2112.00870</a> <span> [<a href="https://arxiv.org/pdf/2112.00870">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Astrophysics of Galaxies">astro-ph.GA</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/ac5fab">10.3847/1538-4357/ac5fab <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Damped Ly-alpha Absorbers in Star-forming Galaxies at z < 0.15 Detected with the Hubble Space Telescope and Implications for Galaxy Evolution </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Kulkarni%2C+V+P">Varsha P. Kulkarni</a>, <a href="/search/physics?searchtype=author&query=Bowen%2C+D+V">David V. Bowen</a>, <a href="/search/physics?searchtype=author&query=Straka%2C+L+A">Lorrie A. Straka</a>, <a href="/search/physics?searchtype=author&query=York%2C+D+G">Donald G. York</a>, <a href="/search/physics?searchtype=author&query=Gupta%2C+N">Neeraj Gupta</a>, <a href="/search/physics?searchtype=author&query=Noterdaeme%2C+P">Pasquier Noterdaeme</a>, <a href="/search/physics?searchtype=author&query=Srianand%2C+R">Raghunathan Srianand</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2112.00870v1-abstract-short" style="display: inline;"> We report {\it HST} COS spectroscopy of 10 quasars with foreground star-forming galaxies at 0.02$<$$z$$<$ 0.14 within impact parameters of $\sim$1-7 kpc. We detect damped/sub-damped Ly$伪$ absorption in 100$\%$ of cases where no higher-redshift Lyman-limit systems extinguish the flux at the expected wavelength of Ly$伪$ absorption, obtaining the largest targeted sample of DLA/sub-DLAs in low-redshif… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2112.00870v1-abstract-full').style.display = 'inline'; document.getElementById('2112.00870v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2112.00870v1-abstract-full" style="display: none;"> We report {\it HST} COS spectroscopy of 10 quasars with foreground star-forming galaxies at 0.02$<$$z$$<$ 0.14 within impact parameters of $\sim$1-7 kpc. We detect damped/sub-damped Ly$伪$ absorption in 100$\%$ of cases where no higher-redshift Lyman-limit systems extinguish the flux at the expected wavelength of Ly$伪$ absorption, obtaining the largest targeted sample of DLA/sub-DLAs in low-redshift galaxies. We present absorption measurements of neutral hydrogen and metals. Additionally, we present GBT 21-cm emission measurements for 5 of the galaxies (including 2 detections). Combining our sample with the literature, we construct a sample of 115 galaxies associated with DLA/sub-DLAs spanning 0$<$$z$$<$4.4, and examine trends between gas and stellar properties, and with redshift. The H~I column density is anti-correlated with impact parameter and stellar mass. More massive galaxies appear to have gas-rich regions out to larger distances. The specific SFR (sSFR) of absorbing galaxies increases with redshift and decreases with $M^{\ast}$, consistent with evolution of the star-formation main sequence (SFMS). However, $\sim$20$\%$ of absorbing galaxies lie below the SFMS, indicating that some DLA/sub-DLAs trace galaxies with longer-than-typical gas-depletion time-scales. Most DLA/sub-DLA galaxies with 21-cm emission have higher H I masses than typical galaxies with comparable $M^{\ast}$. High $M_{\rm H I}/M^{\ast}$ ratios and high sSFRs in DLA/sub-DLA galaxies with $M^{\ast}$$<$$10^{9}$$M_{\odot}$ suggest these galaxies may be gas-rich because of recent gas accretion rather than inefficient star formation. Our study demonstrates the power of absorption and emission studies of DLA/sub-DLA galaxies for extending galaxy-evolution studies to previously under-explored regimes of low $M^{\ast}$ and low SFR. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2112.00870v1-abstract-full').style.display = 'none'; document.getElementById('2112.00870v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 1 December, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">51 pages, 12 figures. Submitted to the Astrophysical Journal</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2101.00293">arXiv:2101.00293</a> <span> [<a href="https://arxiv.org/pdf/2101.00293">pdf</a>, <a href="https://arxiv.org/format/2101.00293">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1016/j.jcis.2020.10.089">10.1016/j.jcis.2020.10.089 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Coalescence and spreading of drops on liquid pools </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Kulkarni%2C+V">Varun Kulkarni</a>, <a href="/search/physics?searchtype=author&query=Lolla%2C+V+Y">Venkata Yashasvi Lolla</a>, <a href="/search/physics?searchtype=author&query=Tamvada%2C+S+R">Suhas Rao Tamvada</a>, <a href="/search/physics?searchtype=author&query=Shirdade%2C+N">Nikhil Shirdade</a>, <a href="/search/physics?searchtype=author&query=Anand%2C+S">Sushant Anand</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2101.00293v3-abstract-short" style="display: inline;"> Oil spills have posed a serious threat to our marine and ecological environment in recent times. Containment of spills proliferating via small drops merging with oceans/seas is especially difficult since their mitigation is closely linked to the coalescence dependent spreading. This inter-connectivity and its dependence on the physical properties of the drop has not been explored until now. Furthe… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2101.00293v3-abstract-full').style.display = 'inline'; document.getElementById('2101.00293v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2101.00293v3-abstract-full" style="display: none;"> Oil spills have posed a serious threat to our marine and ecological environment in recent times. Containment of spills proliferating via small drops merging with oceans/seas is especially difficult since their mitigation is closely linked to the coalescence dependent spreading. This inter-connectivity and its dependence on the physical properties of the drop has not been explored until now. Furthermore, pinch-off behavior and scaling laws for such three-phase systems have not been reported. To this end, we investigate the problem of gentle deposition of a single drop of oil on a pool of water, representative of an oil spill scenario. Methodical study of 11 different n-alkanes, polymers and hydrocarbons with varying viscosity and initial spreading coefficients is conducted. Regime map, scaling laws for deformation features and spreading behavior are established. The existence of a previously undocumented regime of delayed coalescence is revealed. It is seen that the inertia-visco-capillary (I-V-C) scale collapses all experimental drop deformation data on a single line while the early stage spreading is found to be either oscillatory or asymptotically reaching a constant value, depending on the viscosity of the oil drop unlike the well reported monotonic, power law late-time spreading behavior. These findings are equally applicable to applications like emulsions and enhanced oil recovery. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2101.00293v3-abstract-full').style.display = 'none'; document.getElementById('2101.00293v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 25 February, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 1 January, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> J. Colloid Interface Sci 586(2021) 257-268 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2003.11171">arXiv:2003.11171</a> <span> [<a href="https://arxiv.org/pdf/2003.11171">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Applied Physics">physics.app-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1021/acsami.1c24009">10.1021/acsami.1c24009 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Boiling transitions during droplet contact on superheated nano/micro-structured surfaces </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Saneie%2C+N">Navid Saneie</a>, <a href="/search/physics?searchtype=author&query=Kulkarni%2C+V">Varun Kulkarni</a>, <a href="/search/physics?searchtype=author&query=Fezzaa%2C+K">Kamel Fezzaa</a>, <a href="/search/physics?searchtype=author&query=Patankar%2C+N">Neelesh Patankar</a>, <a href="/search/physics?searchtype=author&query=Anand%2C+S">Sushant Anand</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2003.11171v1-abstract-short" style="display: inline;"> Manipulating surface topography is one of the most promising strategies for increasing the efficiency of numerous industrial processes involving droplet contact with superheated surfaces. In such scenarios, the droplets may immediately boil upon contact, splash and boil, or could levitate on their own vapor in the Leidenfrost state. In this work, we report the outcomes of water droplets coming in… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2003.11171v1-abstract-full').style.display = 'inline'; document.getElementById('2003.11171v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2003.11171v1-abstract-full" style="display: none;"> Manipulating surface topography is one of the most promising strategies for increasing the efficiency of numerous industrial processes involving droplet contact with superheated surfaces. In such scenarios, the droplets may immediately boil upon contact, splash and boil, or could levitate on their own vapor in the Leidenfrost state. In this work, we report the outcomes of water droplets coming in gentle contact with designed nano/micro-textured surfaces at a wide range of temperatures as observed using high-speed optical and X-ray imaging. We report a paradoxical increase in the Leidenfrost temperature (TLFP) as the texture spacing is reduced below a critical value (~10 um). Although droplets on such textured solids appear to boil upon contact, our studies suggest that their behavior is dominated by hydrodynamic instabilities implying that the increase in TLFP may not necessarily lead to enhanced heat transfer. On such surfaces, the droplets display a new regime characterized by splashing accompanied by a vapor jet penetrating through the droplets before they transition to the Leidenfrost state. We provide a comprehensive map of boiling behavior of droplets over a wide range of texture spacings that may have significant implications towards applications such as electronics cooling, spray cooling, nuclear reactor safety and containment of fire calamities. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2003.11171v1-abstract-full').style.display = 'none'; document.getElementById('2003.11171v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 24 March, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Navid Saneie and Varun Kulkarni contributed equally to this work. V1.1, 8 pages, 4 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1807.11386">arXiv:1807.11386</a> <span> [<a href="https://arxiv.org/pdf/1807.11386">pdf</a>, <a href="https://arxiv.org/format/1807.11386">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Information Theory">cs.IT</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Physics and Society">physics.soc-ph</span> </div> </div> <p class="title is-5 mathjax"> On the Inability of Markov Models to Capture Criticality in Human Mobility </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Kulkarni%2C+V">Vaibhav Kulkarni</a>, <a href="/search/physics?searchtype=author&query=Mahalunkar%2C+A">Abhijit Mahalunkar</a>, <a href="/search/physics?searchtype=author&query=Garbinato%2C+B">Benoit Garbinato</a>, <a href="/search/physics?searchtype=author&query=Kelleher%2C+J+D">John D. Kelleher</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1807.11386v1-abstract-short" style="display: inline;"> We examine the non-Markovian nature of human mobility by exposing the inability of Markov models to capture criticality in human mobility. In particular, the assumed Markovian nature of mobility was used to establish a theoretical upper bound on the predictability of human mobility (expressed as a minimum error probability limit), based on temporally correlated entropy. Since its inception, this b… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1807.11386v1-abstract-full').style.display = 'inline'; document.getElementById('1807.11386v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1807.11386v1-abstract-full" style="display: none;"> We examine the non-Markovian nature of human mobility by exposing the inability of Markov models to capture criticality in human mobility. In particular, the assumed Markovian nature of mobility was used to establish a theoretical upper bound on the predictability of human mobility (expressed as a minimum error probability limit), based on temporally correlated entropy. Since its inception, this bound has been widely used and empirically validated using Markov chains. We show that recurrent-neural architectures can achieve significantly higher predictability, surpassing this widely used upper bound. In order to explain this anomaly, we shed light on several underlying assumptions in previous research works that has resulted in this bias. By evaluating the mobility predictability on real-world datasets, we show that human mobility exhibits scale-invariant long-range correlations, bearing similarity to a power-law decay. This is in contrast to the initial assumption that human mobility follows an exponential decay. This assumption of exponential decay coupled with Lempel-Ziv compression in computing Fano's inequality has led to an inaccurate estimation of the predictability upper bound. We show that this approach inflates the entropy, consequently lowering the upper bound on human mobility predictability. We finally highlight that this approach tends to overlook long-range correlations in human mobility. This explains why recurrent-neural architectures that are designed to handle long-range structural correlations surpass the previously computed upper bound on mobility predictability. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1807.11386v1-abstract-full').style.display = 'none'; document.getElementById('1807.11386v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 27 July, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2018. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1704.03863">arXiv:1704.03863</a> <span> [<a href="https://arxiv.org/pdf/1704.03863">pdf</a>, <a href="https://arxiv.org/format/1704.03863">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Biological Physics">physics.bio-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantitative Methods">q-bio.QM</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Subcellular Processes">q-bio.SC</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/1478-3975/aa6d89">10.1088/1478-3975/aa6d89 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Stochastic gene expression conditioned on large deviations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Horowitz%2C+J+M">Jordan M. Horowitz</a>, <a href="/search/physics?searchtype=author&query=Kulkarni%2C+R+V">Rahul V. Kulkarni</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1704.03863v1-abstract-short" style="display: inline;"> The intrinsic stochasticity of gene expression can give rise to large fluctuations and rare events that drive phenotypic variation in a population of genetically identical cells. Characterizing the fluctuations that give rise to such rare events motivates the analysis of large deviations in stochastic models of gene expression. Recent developments in non-equilibrium statistical mechanics have led… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1704.03863v1-abstract-full').style.display = 'inline'; document.getElementById('1704.03863v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1704.03863v1-abstract-full" style="display: none;"> The intrinsic stochasticity of gene expression can give rise to large fluctuations and rare events that drive phenotypic variation in a population of genetically identical cells. Characterizing the fluctuations that give rise to such rare events motivates the analysis of large deviations in stochastic models of gene expression. Recent developments in non-equilibrium statistical mechanics have led to a framework for analyzing Markovian processes conditioned on rare events and for representing such processes by conditioning-free driven Markovian processes. We use this framework, in combination with approaches based on queueing theory, to analyze a general class of stochastic models of gene expression. Modeling gene expression as a Batch Markovian Arrival Process (BMAP), we derive exact analytical results quantifying large deviations of time-integrated random variables such as promoter activity fluctuations. We find that the conditioning-free driven process can also be represented by a BMAP that has the same form as the original process, but with renormalized parameters. The results obtained can be used to quantify the likelihood of large deviations, to characterize system fluctuations conditional on rare events and to identify combinations of model parameters that can give rise to dynamical phase transitions in system dynamics. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1704.03863v1-abstract-full').style.display = 'none'; document.getElementById('1704.03863v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 12 April, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2017. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">10 pages, 2 figures, to appear in Physical Biology</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Biol. 14 (2017) 03LT01 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1701.04847">arXiv:1701.04847</a> <span> [<a href="https://arxiv.org/pdf/1701.04847">pdf</a>, <a href="https://arxiv.org/format/1701.04847">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Astrophysics of Galaxies">astro-ph.GA</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4365/aa6d84">10.3847/1538-4365/aa6d84 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Atomic Data Revisions for Transitions Relevant to Observations of Interstellar, Circumgalactic, and Intergalactic Matter </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Cashman%2C+F+H">Frances H. Cashman</a>, <a href="/search/physics?searchtype=author&query=Kulkarni%2C+V+P">Varsha P. Kulkarni</a>, <a href="/search/physics?searchtype=author&query=Kisielius%2C+R">Romas Kisielius</a>, <a href="/search/physics?searchtype=author&query=Ferland%2C+G+J">Gary J. Ferland</a>, <a href="/search/physics?searchtype=author&query=Bogdanovich%2C+P">Pavel Bogdanovich</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1701.04847v3-abstract-short" style="display: inline;"> Measurements of element abundances in galaxies from astrophysical spectroscopy depend sensitively on the atomic data used. With the goal of making the latest atomic data accessible to the community, we present a compilation of selected atomic data for resonant absorption lines at wavelengths longward of 911.753 脜 (the \ion{H}{1} Lyman limit), for key heavy elements (heavier than atomic number 5) o… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1701.04847v3-abstract-full').style.display = 'inline'; document.getElementById('1701.04847v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1701.04847v3-abstract-full" style="display: none;"> Measurements of element abundances in galaxies from astrophysical spectroscopy depend sensitively on the atomic data used. With the goal of making the latest atomic data accessible to the community, we present a compilation of selected atomic data for resonant absorption lines at wavelengths longward of 911.753 脜 (the \ion{H}{1} Lyman limit), for key heavy elements (heavier than atomic number 5) of astrophysical interest. In particular, we focus on the transitions of those ions that have been observed in the Milky Way interstellar medium (ISM), the circumgalactic medium (CGM) of the Milky Way and/or other galaxies, and the intergalactic medium (IGM). We provide wavelengths, oscillator strengths, associated accuracy grades, and references to the oscillator strength determinations. We also attempt to compare and assess the recent oscillator strength determinations. For about 22\% of the lines that have updated oscillator strength values, the differences between the former values and the updated ones are $\gtrsim$~0.1 dex. Our compilation will be a useful resource for absorption line studies of the ISM, as well as studies of the CGM and IGM traced by sight lines to quasars and gamma-ray bursts. Studies (including those enabled by future generations of extremely large telescopes) of absorption by galaxies against the light of background galaxies will also benefit from our compilation. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1701.04847v3-abstract-full').style.display = 'none'; document.getElementById('1701.04847v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 16 June, 2017; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 17 January, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2017. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Final version published in the Astrophysical Journal Supplement Series. Includes 1 machine-readable table</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Astrophysical Journal Supplement Series, 230, 8 (2017) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1605.02115">arXiv:1605.02115</a> <span> [<a href="https://arxiv.org/pdf/1605.02115">pdf</a>, <a href="https://arxiv.org/format/1605.02115">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Social and Information Networks">cs.SI</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Physics and Society">physics.soc-ph</span> </div> </div> <p class="title is-5 mathjax"> Don't Walk, Skip! Online Learning of Multi-scale Network Embeddings </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Perozzi%2C+B">Bryan Perozzi</a>, <a href="/search/physics?searchtype=author&query=Kulkarni%2C+V">Vivek Kulkarni</a>, <a href="/search/physics?searchtype=author&query=Chen%2C+H">Haochen Chen</a>, <a href="/search/physics?searchtype=author&query=Skiena%2C+S">Steven Skiena</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1605.02115v2-abstract-short" style="display: inline;"> We present Walklets, a novel approach for learning multiscale representations of vertices in a network. In contrast to previous works, these representations explicitly encode multiscale vertex relationships in a way that is analytically derivable. Walklets generates these multiscale relationships by subsampling short random walks on the vertices of a graph. By `skipping' over steps in each rando… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1605.02115v2-abstract-full').style.display = 'inline'; document.getElementById('1605.02115v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1605.02115v2-abstract-full" style="display: none;"> We present Walklets, a novel approach for learning multiscale representations of vertices in a network. In contrast to previous works, these representations explicitly encode multiscale vertex relationships in a way that is analytically derivable. Walklets generates these multiscale relationships by subsampling short random walks on the vertices of a graph. By `skipping' over steps in each random walk, our method generates a corpus of vertex pairs which are reachable via paths of a fixed length. This corpus can then be used to learn a series of latent representations, each of which captures successively higher order relationships from the adjacency matrix. We demonstrate the efficacy of Walklets's latent representations on several multi-label network classification tasks for social networks such as BlogCatalog, DBLP, Flickr, and YouTube. Our results show that Walklets outperforms new methods based on neural matrix factorization. Specifically, we outperform DeepWalk by up to 10% and LINE by 58% Micro-F1 on challenging multi-label classification tasks. Finally, Walklets is an online algorithm, and can easily scale to graphs with millions of vertices and edges. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1605.02115v2-abstract-full').style.display = 'none'; document.getElementById('1605.02115v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 24 June, 2017; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 6 May, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2016. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">8 pages, ASONAM'17</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1511.08388">arXiv:1511.08388</a> <span> [<a href="https://arxiv.org/pdf/1511.08388">pdf</a>, <a href="https://arxiv.org/ps/1511.08388">ps</a>, <a href="https://arxiv.org/format/1511.08388">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Optics">physics.optics</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1364/OE.23.015641">10.1364/OE.23.015641 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Electromagnetic cloaking in convex and concave media with surface modelled as a parameterised function </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Sidhwa%2C+H+H">H. H. Sidhwa</a>, <a href="/search/physics?searchtype=author&query=Aiyar%2C+R+P">R. P. Aiyar</a>, <a href="/search/physics?searchtype=author&query=Kulkarni%2C+S+V">S. V. Kulkarni</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1511.08388v1-abstract-short" style="display: inline;"> The onset of transformation optics has opened avenues for designing of a plenitude of applications related to propagation of electromagnetic waves in anisotropic media. In this paper, an algorithm is proposed using a coordinate transformation and a piecewise function for the purpose of designing a three dimensional cloak having an arbitrary geometry which could be convex or non-convex in nature. T… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1511.08388v1-abstract-full').style.display = 'inline'; document.getElementById('1511.08388v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1511.08388v1-abstract-full" style="display: none;"> The onset of transformation optics has opened avenues for designing of a plenitude of applications related to propagation of electromagnetic waves in anisotropic media. In this paper, an algorithm is proposed using a coordinate transformation and a piecewise function for the purpose of designing a three dimensional cloak having an arbitrary geometry which could be convex or non-convex in nature. The surfaces of the cloak as well as of the body under consideration are assumed to be conformal to each other. For an arbitrary geometry, the coordinate system needed to model the surface can be a non-orthogonal system. For the purpose of verification of the algorithm, a ray tracing process is carried out for an ellipsoid as well as for a concave surface having axial symmetry. In order to solve the Hamiltonian equation for the purpose of ray tracing, the process of finding the derivatives analytically, for an arbitrary geometry as considered here, becomes very cumbersome. Here, a numerical method is described which provides a better approximation to the partial derivatives than the conventional finite difference approach based on forward differences. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1511.08388v1-abstract-full').style.display = 'none'; document.getElementById('1511.08388v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 26 November, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2015. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">12 pages, 8 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Optics Express 23 15641 (2015) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1511.08351">arXiv:1511.08351</a> <span> [<a href="https://arxiv.org/pdf/1511.08351">pdf</a>, <a href="https://arxiv.org/ps/1511.08351">ps</a>, <a href="https://arxiv.org/format/1511.08351">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Optics">physics.optics</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.13140/2.1.3831.3928">10.13140/2.1.3831.3928 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Ray Tracing in an Arbitrary Cloak in Two Dimensions </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Sidhwa%2C+H+H">H. H. Sidhwa</a>, <a href="/search/physics?searchtype=author&query=Aiyar%2C+R+P">R. P. Aiyar</a>, <a href="/search/physics?searchtype=author&query=Kulkarni%2C+S+V">S. V. Kulkarni</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1511.08351v1-abstract-short" style="display: inline;"> Electromagnetic wave behaviour in an anisotropic medium with a two dimensional arbitrary geometry is studied. The aim is to trace the path of a ray in such a complex medium for the purpose of achieving cloaking (invisibility). A coordinate transformation is carried out for the formulation of an annular region at the centre of the structure whose topology is a scaled geometry of outer boundary of t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1511.08351v1-abstract-full').style.display = 'inline'; document.getElementById('1511.08351v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1511.08351v1-abstract-full" style="display: none;"> Electromagnetic wave behaviour in an anisotropic medium with a two dimensional arbitrary geometry is studied. The aim is to trace the path of a ray in such a complex medium for the purpose of achieving cloaking (invisibility). A coordinate transformation is carried out for the formulation of an annular region at the centre of the structure whose topology is a scaled geometry of outer boundary of the structure. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1511.08351v1-abstract-full').style.display = 'none'; document.getElementById('1511.08351v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 26 November, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2015. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">4 pages, 1 figure , Progress in Electromagnetics Research Symposium (PIERS) 2013 Stockholm, Sweden</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1412.8634">arXiv:1412.8634</a> <span> [<a href="https://arxiv.org/pdf/1412.8634">pdf</a>, <a href="https://arxiv.org/ps/1412.8634">ps</a>, <a href="https://arxiv.org/format/1412.8634">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Molecular Networks">q-bio.MN</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Biological Physics">physics.bio-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1371/journal.pcbi.1004292">10.1371/journal.pcbi.1004292 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Transcriptional bursting in gene expression: analytical results for general stochastic models </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Kumar%2C+N">Niraj Kumar</a>, <a href="/search/physics?searchtype=author&query=Singh%2C+A">Abhyudai Singh</a>, <a href="/search/physics?searchtype=author&query=Kulkarni%2C+R+V">Rahul V. Kulkarni</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1412.8634v1-abstract-short" style="display: inline;"> Gene expression in individual cells is highly variable and sporadic, often resulting in the synthesis of mRNAs and proteins in bursts. Bursting in gene expression is known to impact cell-fate in diverse systems ranging from latency in HIV-1 viral infections to cellular differentiation. It is generally assumed that bursts are geometrically distributed and that they arrive according to a Poisson pro… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1412.8634v1-abstract-full').style.display = 'inline'; document.getElementById('1412.8634v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1412.8634v1-abstract-full" style="display: none;"> Gene expression in individual cells is highly variable and sporadic, often resulting in the synthesis of mRNAs and proteins in bursts. Bursting in gene expression is known to impact cell-fate in diverse systems ranging from latency in HIV-1 viral infections to cellular differentiation. It is generally assumed that bursts are geometrically distributed and that they arrive according to a Poisson process. On the other hand, recent single-cell experiments provide evidence for complex burst arrival processes, highlighting the need for more general stochastic models. To address this issue, we invoke a mapping between general models of gene expression and systems studied in queueing theory to derive exact analytical expressions for the moments associated with mRNA/protein steady-state distributions. These moments are then used to derive explicit conditions, based entirely on experimentally measurable quantities, that determine if the burst distributions deviate from the geometric distribution or if burst arrival deviates from a Poisson process. For non-Poisson arrivals, we develop approaches for accurate estimation of burst parameters. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1412.8634v1-abstract-full').style.display = 'none'; document.getElementById('1412.8634v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 30 December, 2014; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2014. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1409.3499">arXiv:1409.3499</a> <span> [<a href="https://arxiv.org/pdf/1409.3499">pdf</a>, <a href="https://arxiv.org/format/1409.3499">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Molecular Networks">q-bio.MN</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Biological Physics">physics.bio-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.113.268105">10.1103/PhysRevLett.113.268105 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Exact distributions for stochastic gene expression models with bursting and feedback </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Kumar%2C+N">Niraj Kumar</a>, <a href="/search/physics?searchtype=author&query=Platini%2C+T">Thierry Platini</a>, <a href="/search/physics?searchtype=author&query=Kulkarni%2C+R+V">Rahul V. Kulkarni</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1409.3499v2-abstract-short" style="display: inline;"> Stochasticity in gene expression can give rise to fluctuations in protein levels and lead to phenotypic variation across a population of genetically identical cells. Recent experiments indicate that bursting and feedback mechanisms play important roles in controlling noise in gene expression and phenotypic variation. A quantitative understanding of the impact of these factors requires analysis of… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1409.3499v2-abstract-full').style.display = 'inline'; document.getElementById('1409.3499v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1409.3499v2-abstract-full" style="display: none;"> Stochasticity in gene expression can give rise to fluctuations in protein levels and lead to phenotypic variation across a population of genetically identical cells. Recent experiments indicate that bursting and feedback mechanisms play important roles in controlling noise in gene expression and phenotypic variation. A quantitative understanding of the impact of these factors requires analysis of the corresponding stochastic models. However, for stochastic models of gene expression with feedback and bursting, exact analytical results for protein distributions have not been obtained so far. Here, we analyze a model of gene expression with bursting and feedback regulation and obtain exact results for the corresponding protein steady-state distribution. The results obtained provide new insights into the role of bursting and feedback in noise regulation and optimization. Furthermore, for a specific choice of parameters, the system studied maps on to a two-state biochemical switch driven by a bursty input noise source. The analytical results derived thus provide quantitative insights into diverse cellular processes involving noise in gene expression and biochemical switching. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1409.3499v2-abstract-full').style.display = 'none'; document.getElementById('1409.3499v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 26 November, 2014; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 11 September, 2014; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2014. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted in Phys. Rev. Lett</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1408.5079">arXiv:1408.5079</a> <span> [<a href="https://arxiv.org/pdf/1408.5079">pdf</a>, <a href="https://arxiv.org/format/1408.5079">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Physics and Society">physics.soc-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Social and Information Networks">cs.SI</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Adaptation and Self-Organizing Systems">nlin.AO</span> </div> </div> <p class="title is-5 mathjax"> Temporal Evolution of Social Innovation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Kulkarni%2C+V+S">Varsha S. Kulkarni</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1408.5079v1-abstract-short" style="display: inline;"> Acceptance of an innovation can occur through mutliple exposures to individuals who have already accepted it. Presented here is a model to trace the evolution of an innovation in a social network with a preference $位$, amidst topological constraints specified mainly by connectivity, $k$ and population size, $N_k$. With the interplay between properties of innovation and network structure, the model… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1408.5079v1-abstract-full').style.display = 'inline'; document.getElementById('1408.5079v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1408.5079v1-abstract-full" style="display: none;"> Acceptance of an innovation can occur through mutliple exposures to individuals who have already accepted it. Presented here is a model to trace the evolution of an innovation in a social network with a preference $位$, amidst topological constraints specified mainly by connectivity, $k$ and population size, $N_k$. With the interplay between properties of innovation and network structure, the model attempts to explain the variations in patterns of innovations across social networks. Time in which the propagation attains highest velocity depends on $位^{-2}k^{-2}N_{k}^{1/2}$. Dynamics in random networks may lead or lag behind that in scale-free networks depending on the average connectivity. Hierarchical propagation is evident across connectivity classes within scale-free networks, as well as across random networks with distinct topological indices. For highly preferred innovations, the hierarchy observed within scale-free networks tends to be insignificant. The results have implications for administering innovations in finite size networks. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1408.5079v1-abstract-full').style.display = 'none'; document.getElementById('1408.5079v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 21 August, 2014; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2014. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1308.1616">arXiv:1308.1616</a> <span> [<a href="https://arxiv.org/pdf/1308.1616">pdf</a>, <a href="https://arxiv.org/format/1308.1616">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="General Finance">q-fin.GN</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Data Analysis, Statistics and Probability">physics.data-an</span> </div> </div> <p class="title is-5 mathjax"> Complexity, Chaos, and the Duffing-Oscillator Model: An Analysis of Inventory Fluctuations in Markets </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Kulkarni%2C+V+S">Varsha S. Kulkarni</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1308.1616v1-abstract-short" style="display: inline;"> Apparently random financial fluctuations often exhibit varying levels of complexity, chaos. Given limited data, predictability of such time series becomes hard to infer. While efficient methods of Lyapunov exponent computation are devised, knowledge about the process driving the dynamics greatly facilitates the complexity analysis. This paper shows that quarterly inventory changes of wheat in the… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1308.1616v1-abstract-full').style.display = 'inline'; document.getElementById('1308.1616v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1308.1616v1-abstract-full" style="display: none;"> Apparently random financial fluctuations often exhibit varying levels of complexity, chaos. Given limited data, predictability of such time series becomes hard to infer. While efficient methods of Lyapunov exponent computation are devised, knowledge about the process driving the dynamics greatly facilitates the complexity analysis. This paper shows that quarterly inventory changes of wheat in the global market, during 1974-2012, follow a nonlinear deterministic process. Lyapunov exponents of these fluctuations are computed using sliding time windows each of length 131 quarters. Weakly chaotic behavior alternates with non-chaotic behavior over the entire period of analysis. More importantly, in this paper, a cubic dependence of price changes on inventory changes leads to establishment of deterministic Duffing-Oscillator-Model(DOM) as a suitable candidate for examining inventory fluctuations of wheat. DOM represents the interaction of commodity production cycle with an external intervention in the market. Parameters obtained for shifting time zones by fitting the Fourier estimated time signals to DOM are able to generate responses that reproduce the true chaotic nature exhibited by the empirical signal at that time. Endowing the parameters with suitable meanings, one may infer that temporary changes in speculation reflect the pattern of inventory volatility that drives the transitions between chaotic and non-chaotic behavior. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1308.1616v1-abstract-full').style.display = 'none'; document.getElementById('1308.1616v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 24 July, 2013; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2013. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1304.6570">arXiv:1304.6570</a> <span> [<a href="https://arxiv.org/pdf/1304.6570">pdf</a>, <a href="https://arxiv.org/format/1304.6570">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Molecular Networks">q-bio.MN</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Biological Physics">physics.bio-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevE.87.042720">10.1103/PhysRevE.87.042720 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Exact protein distributions for stochastic models of gene expression using partitioning of Poisson processes </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Pendar%2C+H">Hodjat Pendar</a>, <a href="/search/physics?searchtype=author&query=Platini%2C+T">Thierry Platini</a>, <a href="/search/physics?searchtype=author&query=Kulkarni%2C+R+V">Rahul V. Kulkarni</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1304.6570v1-abstract-short" style="display: inline;"> Stochasticity in gene expression gives rise to fluctuations in protein levels across a population of genetically identical cells. Such fluctuations can lead to phenotypic variation in clonal populations, hence there is considerable interest in quantifying noise in gene expression using stochastic models. However, obtaining exact analytical results for protein distributions has been an intractable… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1304.6570v1-abstract-full').style.display = 'inline'; document.getElementById('1304.6570v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1304.6570v1-abstract-full" style="display: none;"> Stochasticity in gene expression gives rise to fluctuations in protein levels across a population of genetically identical cells. Such fluctuations can lead to phenotypic variation in clonal populations, hence there is considerable interest in quantifying noise in gene expression using stochastic models. However, obtaining exact analytical results for protein distributions has been an intractable task for all but the simplest models. Here, we invoke the partitioning property of Poisson processes to develop a mapping that significantly simplifies the analysis of stochastic models of gene expression. The mapping leads to exact protein distributions using results for mRNA distributions in models with promoter-based regulation. Using this approach, we derive exact analytical results for steady-state and time-dependent distributions for the basic 2-stage model of gene expression. Furthermore, we show how the mapping leads to exact protein distributions for extensions of the basic model that include the effects of post-transcriptional and post-translational regulation. The approach developed in this work is widely applicable and can contribute to a quantitative understanding of stochasticity in gene expression and its regulation. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1304.6570v1-abstract-full').style.display = 'none'; document.getElementById('1304.6570v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 24 April, 2013; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2013. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">10 pages, 5 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1202.0882">arXiv:1202.0882</a> <span> [<a href="https://arxiv.org/pdf/1202.0882">pdf</a>, <a href="https://arxiv.org/ps/1202.0882">ps</a>, <a href="https://arxiv.org/format/1202.0882">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Cosmology and Nongalactic Astrophysics">astro-ph.CO</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> </div> </div> <p class="title is-5 mathjax"> A Super-Damped Lyman-alpha QSO Absorber at z=2.2 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Kulkarni%2C+V+P">Varsha P. Kulkarni</a>, <a href="/search/physics?searchtype=author&query=Meiring%2C+J">Joseph Meiring</a>, <a href="/search/physics?searchtype=author&query=Som%2C+D">Debopam Som</a>, <a href="/search/physics?searchtype=author&query=Peroux%2C+C">Celine Peroux</a>, <a href="/search/physics?searchtype=author&query=York%2C+D+G">Donald G. York</a>, <a href="/search/physics?searchtype=author&query=Khare%2C+P">Pushpa Khare</a>, <a href="/search/physics?searchtype=author&query=Lauroesch%2C+J+T">James T. Lauroesch</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1202.0882v2-abstract-short" style="display: inline;"> We report the discovery of a "super-damped" Lyman-alpha absorber at $z_{abs}=2.2068$ toward QSO Q1135-0010 in the Sloan Digital Sky Survey, and follow-up VLT UVES spectroscopy. Voigt profile fit to the DLA line indicates log $N_{\rm H I} = 22.05 \pm 0.1$. This is the second QSO DLA discovered to date with such high $N_{\rm H I}$. We derive element abundances [Si/H] = $-1.10 \pm 0.10$, [Zn/H] =… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1202.0882v2-abstract-full').style.display = 'inline'; document.getElementById('1202.0882v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1202.0882v2-abstract-full" style="display: none;"> We report the discovery of a "super-damped" Lyman-alpha absorber at $z_{abs}=2.2068$ toward QSO Q1135-0010 in the Sloan Digital Sky Survey, and follow-up VLT UVES spectroscopy. Voigt profile fit to the DLA line indicates log $N_{\rm H I} = 22.05 \pm 0.1$. This is the second QSO DLA discovered to date with such high $N_{\rm H I}$. We derive element abundances [Si/H] = $-1.10 \pm 0.10$, [Zn/H] = $-1.06 \pm 0.10$, [Cr/H] = $-1.55 \pm 0.10$, [Ni/H] = $-1.60 \pm 0.10$, [Fe/H] = $-1.76 \pm 0.10$, [Ti/H] = $-1.69 \pm 0.11$, [P/H] = $-0.93 \pm 0.23$, and [Cu/H] = $-0.75 \pm 0.14$. Our data indicate detection of Ly-$伪$ emission in the DLA trough, implying a star formation rate of $\sim$10 $M_{\odot}$ yr$^{-1}$ in the absence of dust attenuation. C II$^{*} \, 位1336$ absorption is also detected, suggesting SFR surface density $-2 < {\rm log} \, \dot{蠄_{*}} < 0$ $M_{\odot}$ yr$^{-1}$ kpc$^{-2}$. We estimate electron density in the range $3.5 \times 10^{-4}$ to 24.7 cm$^{-3}$ from C II$^{*}$/C II, and $\sim$0.5-0.9 cm$^{-3}$ from Si II$^{*}$/Si II. Overall, this is a robustly star-forming, moderately enriched absorber, but with relatively low dust depletion. Fitting of the SDSS spectrum yields low reddening for Milky Way, LMC, or SMC extinction curves. No CO absorption is detected, and C I absorption is weak. The low dust and molecular content, reminiscent of some SMC sight-lines, may result from the lower metallicity, and a stronger radiation field (due to higher SFR). Finally, we compare this absorber with other QSO and GRB DLAs. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1202.0882v2-abstract-full').style.display = 'none'; document.getElementById('1202.0882v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 21 February, 2012; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 4 February, 2012; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2012. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in the Astrophysical Journal. Submitted Dec. 10, 2011; accepted Feb. 19, 2012</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1103.0048">arXiv:1103.0048</a> <span> [<a href="https://arxiv.org/pdf/1103.0048">pdf</a>, <a href="https://arxiv.org/ps/1103.0048">ps</a>, <a href="https://arxiv.org/format/1103.0048">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Physics and Society">physics.soc-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Disordered Systems and Neural Networks">cond-mat.dis-nn</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Social and Information Networks">cs.SI</span> </div> </div> <p class="title is-5 mathjax"> On the structural properties of small-world networks with finite range of shortcut links </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Jia%2C+T">Tao Jia</a>, <a href="/search/physics?searchtype=author&query=Kulkarni%2C+R+V">Rahul V. Kulkarni</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1103.0048v1-abstract-short" style="display: inline;"> We explore a new variant of Small-World Networks (SWNs), in which an additional parameter ($r$) sets the length scale over which shortcuts are uniformly distributed. When $r=0$ we have an ordered network, whereas $r=1$ corresponds to the original SWN model. These short-range SWNs have a similar degree distribution and scaling properties as the original SWN model. We observe the small-world phenome… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1103.0048v1-abstract-full').style.display = 'inline'; document.getElementById('1103.0048v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1103.0048v1-abstract-full" style="display: none;"> We explore a new variant of Small-World Networks (SWNs), in which an additional parameter ($r$) sets the length scale over which shortcuts are uniformly distributed. When $r=0$ we have an ordered network, whereas $r=1$ corresponds to the original SWN model. These short-range SWNs have a similar degree distribution and scaling properties as the original SWN model. We observe the small-world phenomenon for $r \ll 1$ indicating that global shortcuts are not necessary for the small-world effect. For short-range SWNs, the average path length changes nonmonotonically with system size, whereas for the original SWN model it increases monotonically. We propose an expression for the average path length for short-range SWNs based on numerical simulations and analytical approximations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1103.0048v1-abstract-full').style.display = 'none'; document.getElementById('1103.0048v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 28 February, 2011; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2011. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1102.4576">arXiv:1102.4576</a> <span> [<a href="https://arxiv.org/pdf/1102.4576">pdf</a>, <a href="https://arxiv.org/ps/1102.4576">ps</a>, <a href="https://arxiv.org/format/1102.4576">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Biological Physics">physics.bio-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/1478-3975/8/4/046001">10.1088/1478-3975/8/4/046001 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Connecting protein and mRNA burst distributions for stochastic models of gene expression </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Elgart%2C+V">Vlad Elgart</a>, <a href="/search/physics?searchtype=author&query=Jia%2C+T">Tao Jia</a>, <a href="/search/physics?searchtype=author&query=Fenley%2C+A+T">Andrew T. Fenley</a>, <a href="/search/physics?searchtype=author&query=Kulkarni%2C+R+V">Rahul V. Kulkarni</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1102.4576v1-abstract-short" style="display: inline;"> The intrinsic stochasticity of gene expression can lead to large variability in protein levels for genetically identical cells. Such variability in protein levels can arise from infrequent synthesis of mRNAs which in turn give rise to bursts of protein expression. Protein expression occurring in bursts has indeed been observed experimentally and recent studies have also found evidence for transcri… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1102.4576v1-abstract-full').style.display = 'inline'; document.getElementById('1102.4576v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1102.4576v1-abstract-full" style="display: none;"> The intrinsic stochasticity of gene expression can lead to large variability in protein levels for genetically identical cells. Such variability in protein levels can arise from infrequent synthesis of mRNAs which in turn give rise to bursts of protein expression. Protein expression occurring in bursts has indeed been observed experimentally and recent studies have also found evidence for transcriptional bursting, i.e. production of mRNAs in bursts. Given that there are distinct experimental techniques for quantifying the noise at different stages of gene expression, it is of interest to derive analytical results connecting experimental observations at different levels. In this work, we consider stochastic models of gene expression for which mRNA and protein production occurs in independent bursts. For such models, we derive analytical expressions connecting protein and mRNA burst distributions which show how the functional form of the mRNA burst distribution can be inferred from the protein burst distribution. Additionally, if gene expression is repressed such that observed protein bursts arise only from single mRNAs, we show how observations of protein burst distributions (repressed and unrepressed) can be used to completely determine the mRNA burst distribution. Assuming independent contributions from individual bursts, we derive analytical expressions connecting means and variances for burst and steady-state protein distributions. Finally, we validate our general analytical results by considering a specific reaction scheme involving regulation of protein bursts by small RNAs. For a range of parameters, we derive analytical expressions for regulated protein distributions that are validated using stochastic simulations. The analytical results obtained in this work can thus serve as useful inputs for a broad range of studies focusing on stochasticity in gene expression. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1102.4576v1-abstract-full').style.display = 'none'; document.getElementById('1102.4576v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 22 February, 2011; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2011. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1102.3991">arXiv:1102.3991</a> <span> [<a href="https://arxiv.org/pdf/1102.3991">pdf</a>, <a href="https://arxiv.org/ps/1102.3991">ps</a>, <a href="https://arxiv.org/format/1102.3991">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Biological Physics">physics.bio-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Molecular Networks">q-bio.MN</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevE.84.021928">10.1103/PhysRevE.84.021928 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Regulation by small RNAs via coupled degradation: mean-field and variational approaches </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Platini%2C+T">Thierry Platini</a>, <a href="/search/physics?searchtype=author&query=Jia%2C+T">Tao Jia</a>, <a href="/search/physics?searchtype=author&query=Kulkarni%2C+R+V">Rahul V. Kulkarni</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1102.3991v1-abstract-short" style="display: inline;"> Regulatory genes called small RNAs (sRNAs) are known to play critical roles in cellular responses to changing environments. For several sRNAs, regulation is effected by coupled stoichiometric degradation with messenger RNAs (mRNAs). The nonlinearity inherent in this regulatory scheme indicates that exact analytical solutions for the corresponding stochastic models are intractable. Here, we present… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1102.3991v1-abstract-full').style.display = 'inline'; document.getElementById('1102.3991v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1102.3991v1-abstract-full" style="display: none;"> Regulatory genes called small RNAs (sRNAs) are known to play critical roles in cellular responses to changing environments. For several sRNAs, regulation is effected by coupled stoichiometric degradation with messenger RNAs (mRNAs). The nonlinearity inherent in this regulatory scheme indicates that exact analytical solutions for the corresponding stochastic models are intractable. Here, we present a variational approach to analyze a well-studied stochastic model for regulation by sRNAs via coupled degradation. The proposed approach is efficient and provides accurate estimates of mean mRNA levels as well as higher order terms. Results from the variational ansatz are in excellent agreement with data from stochastic simulations for a wide range of parameters, including regions of parameter space where mean-field approaches break down. The proposed approach can be applied to quantitatively model stochastic gene expression in complex regulatory networks. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1102.3991v1-abstract-full').style.display = 'none'; document.getElementById('1102.3991v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 19 February, 2011; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2011. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">4 pages, 3 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1101.5861">arXiv:1101.5861</a> <span> [<a href="https://arxiv.org/pdf/1101.5861">pdf</a>, <a href="https://arxiv.org/ps/1101.5861">ps</a>, <a href="https://arxiv.org/format/1101.5861">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Molecular Networks">q-bio.MN</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Biological Physics">physics.bio-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevE.85.061915">10.1103/PhysRevE.85.061915 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Stochastic modeling of regulation of gene expression by multiple small RNAs </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Baker%2C+C">Charles Baker</a>, <a href="/search/physics?searchtype=author&query=Jia%2C+T">Tao Jia</a>, <a href="/search/physics?searchtype=author&query=Kulkarni%2C+R+V">Rahul V. Kulkarni</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1101.5861v2-abstract-short" style="display: inline;"> A wealth of new research has highlighted the critical roles of small RNAs (sRNAs) in diverse processes such as quorum sensing and cellular responses to stress. The pathways controlling these processes often have a central motif comprising of a master regulator protein whose expression is controlled by multiple sRNAs. However, the regulation of stochastic gene expression of a single target gene by… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1101.5861v2-abstract-full').style.display = 'inline'; document.getElementById('1101.5861v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1101.5861v2-abstract-full" style="display: none;"> A wealth of new research has highlighted the critical roles of small RNAs (sRNAs) in diverse processes such as quorum sensing and cellular responses to stress. The pathways controlling these processes often have a central motif comprising of a master regulator protein whose expression is controlled by multiple sRNAs. However, the regulation of stochastic gene expression of a single target gene by multiple sRNAs is currently not well understood. To address this issue, we analyze a stochastic model of regulation of gene expression by multiple sRNAs. For this model, we derive exact analytic results for the regulated protein distribution including compact expressions for its mean and variance. The derived results provide novel insights into the roles of multiple sRNAs in fine-tuning the noise in gene expression. In particular, we show that, in contrast to regulation by a single sRNA, multiple sRNAs provide a mechanism for independently controlling the mean and variance of the regulated protein distribution. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1101.5861v2-abstract-full').style.display = 'none'; document.getElementById('1101.5861v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 11 February, 2011; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 31 January, 2011; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2011. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1101.5216">arXiv:1101.5216</a> <span> [<a href="https://arxiv.org/pdf/1101.5216">pdf</a>, <a href="https://arxiv.org/ps/1101.5216">ps</a>, <a href="https://arxiv.org/format/1101.5216">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Molecular Networks">q-bio.MN</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Biological Physics">physics.bio-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Subcellular Processes">q-bio.SC</span> </div> </div> <p class="title is-5 mathjax"> Computational modeling of differences in the quorum sensing induced luminescence phenotypes of \textit{Vibrio harveyi} and \textit{Vibrio cholerae} </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Fenley%2C+A+T">Andrew T Fenley</a>, <a href="/search/physics?searchtype=author&query=Banik%2C+S+K">Suman K Banik</a>, <a href="/search/physics?searchtype=author&query=Kulkarni%2C+R+V">Rahul V Kulkarni</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1101.5216v1-abstract-short" style="display: inline;"> \textit{Vibrio harveyi} and \textit{Vibrio cholerae} have quorum sensing pathways with similar design and highly homologous components including multiple small RNAs (sRNAs). However, the associated luminescence phenotypes of strains with sRNA deletions differ dramatically: in \textit{V. harveyi}, the sRNAs act additively; however, in \textit{V. cholerae}, the sRNAs act redundantly. Furthermore, th… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1101.5216v1-abstract-full').style.display = 'inline'; document.getElementById('1101.5216v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1101.5216v1-abstract-full" style="display: none;"> \textit{Vibrio harveyi} and \textit{Vibrio cholerae} have quorum sensing pathways with similar design and highly homologous components including multiple small RNAs (sRNAs). However, the associated luminescence phenotypes of strains with sRNA deletions differ dramatically: in \textit{V. harveyi}, the sRNAs act additively; however, in \textit{V. cholerae}, the sRNAs act redundantly. Furthermore, there are striking differences in the luminescence phenotypes for different pathway mutants in \textit{V. harveyi} and \textit{V. cholerae}. However these differences have not been connected with the observed differences for the sRNA deletion strains in these bacteria. In this work, we present a model for quorum sensing induced luminescence phenotypes focusing on the interactions of multiple sRNAs with target mRNA. Within our model, we find that one key parameter -- the fold-change in protein concentration necessary for luminescence activation -- can control whether the sRNAs appear to act additively or redundantly. For specific parameter choices, we find that differences in this key parameter can also explain hitherto unconnected luminescence phenotypes differences for various pathway mutants in \textit{V. harveyi} and \textit{V. cholerae}. The model can thus provide a unifying explanation for observed differences in luminescence phenotypes and can also be used to make testable predictions for future experiments. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1101.5216v1-abstract-full').style.display = 'none'; document.getElementById('1101.5216v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 27 January, 2011; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2011. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">10 pages, 6 figures and 1 table</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1007.1928">arXiv:1007.1928</a> <span> [<a href="https://arxiv.org/pdf/1007.1928">pdf</a>, <a href="https://arxiv.org/ps/1007.1928">ps</a>, <a href="https://arxiv.org/format/1007.1928">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Biological Physics">physics.bio-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Molecular Networks">q-bio.MN</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevE.82.021901">10.1103/PhysRevE.82.021901 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Applications of Little's Law to stochastic models of gene expression </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Elgart%2C+V">Vlad Elgart</a>, <a href="/search/physics?searchtype=author&query=Jia%2C+T">Tao Jia</a>, <a href="/search/physics?searchtype=author&query=Kulkarni%2C+R+V">Rahul V. Kulkarni</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1007.1928v1-abstract-short" style="display: inline;"> The intrinsic stochasticity of gene expression can lead to large variations in protein levels across a population of cells. To explain this variability, different sources of mRNA fluctuations ('Poisson' and 'Telegraph' processes) have been proposed in stochastic models of gene expression. Both Poisson and Telegraph scenario models explain experimental observations of noise in protein levels in ter… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1007.1928v1-abstract-full').style.display = 'inline'; document.getElementById('1007.1928v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1007.1928v1-abstract-full" style="display: none;"> The intrinsic stochasticity of gene expression can lead to large variations in protein levels across a population of cells. To explain this variability, different sources of mRNA fluctuations ('Poisson' and 'Telegraph' processes) have been proposed in stochastic models of gene expression. Both Poisson and Telegraph scenario models explain experimental observations of noise in protein levels in terms of 'bursts' of protein expression. Correspondingly, there is considerable interest in establishing relations between burst and steady-state protein distributions for general stochastic models of gene expression. In this work, we address this issue by considering a mapping between stochastic models of gene expression and problems of interest in queueing theory. By applying a general theorem from queueing theory, Little's Law, we derive exact relations which connect burst and steady-state distribution means for models with arbitrary waiting-time distributions for arrival and degradation of mRNAs and proteins. The derived relations have implications for approaches to quantify the degree of transcriptional bursting and hence to discriminate between different sources of intrinsic noise in gene expression. To illustrate this, we consider a model for regulation of protein expression bursts by small RNAs. For a broad range of parameters, we derive analytical expressions (validated by stochastic simulations) for the mean protein levels as the levels of regulatory small RNAs are varied. The results obtained show that the degree of transcriptional bursting can, in principle, be determined from changes in mean steady-state protein levels for general stochastic models of gene expression. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1007.1928v1-abstract-full').style.display = 'none'; document.getElementById('1007.1928v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 12 July, 2010; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2010. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted by Physical Review E</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. E 82, 021901, 2010 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1006.4113">arXiv:1006.4113</a> <span> [<a href="https://arxiv.org/pdf/1006.4113">pdf</a>, <a href="https://arxiv.org/ps/1006.4113">ps</a>, <a href="https://arxiv.org/format/1006.4113">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Molecular Networks">q-bio.MN</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Biological Physics">physics.bio-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.105.018101">10.1103/PhysRevLett.105.018101 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Post-transcriptional regulation of noise in protein distributions during gene expression </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Jia%2C+T">Tao Jia</a>, <a href="/search/physics?searchtype=author&query=Kulkarni%2C+R+V">Rahul V. Kulkarni</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1006.4113v1-abstract-short" style="display: inline;"> The intrinsic stochasticity of gene expression can lead to large variability of protein levels across a population of cells. Variability (or noise) in protein distributions can be modulated by cellular mechanisms of gene regulation; in particular, there is considerable interest in understanding the role of post-transcriptional regulation. To address this issue, we propose and analyze a stochastic… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1006.4113v1-abstract-full').style.display = 'inline'; document.getElementById('1006.4113v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1006.4113v1-abstract-full" style="display: none;"> The intrinsic stochasticity of gene expression can lead to large variability of protein levels across a population of cells. Variability (or noise) in protein distributions can be modulated by cellular mechanisms of gene regulation; in particular, there is considerable interest in understanding the role of post-transcriptional regulation. To address this issue, we propose and analyze a stochastic model for post-transcriptional regulation of gene expression. The analytical solution of the model provides insight into the effects of different mechanisms of post-transcriptional regulation on the noise in protein distributions. The results obtained also demonstrate how different sources of intrinsic noise in gene expression can be discriminated based on observations of regulated protein distributions. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1006.4113v1-abstract-full').style.display = 'none'; document.getElementById('1006.4113v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 21 June, 2010; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2010. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted by Physical Review Letters</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 105, 018101, 2010 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/physics/0512169">arXiv:physics/0512169</a> <span> [<a href="https://arxiv.org/pdf/physics/0512169">pdf</a>, <a href="https://arxiv.org/ps/physics/0512169">ps</a>, <a href="https://arxiv.org/format/physics/0512169">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Physics and Society">physics.soc-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Finance">q-fin.ST</span> </div> </div> <p class="title is-5 mathjax"> Volatility of an Indian stock market : A random matrix approach </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Kulkarni%2C+V">V. Kulkarni</a>, <a href="/search/physics?searchtype=author&query=Deo%2C+N">N. Deo</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="physics/0512169v1-abstract-short" style="display: inline;"> We examine volatility of an Indian stock market in terms of aspects like participation, synchronization of stocks and quantification of volatility using the random matrix approach. Volatility pattern of the market is found using the BSE index for the three-year period 2000-2002. Random matrix analysis is carried out using daily returns of 70 stocks for several time windows of 85 days in 2001 to… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('physics/0512169v1-abstract-full').style.display = 'inline'; document.getElementById('physics/0512169v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="physics/0512169v1-abstract-full" style="display: none;"> We examine volatility of an Indian stock market in terms of aspects like participation, synchronization of stocks and quantification of volatility using the random matrix approach. Volatility pattern of the market is found using the BSE index for the three-year period 2000-2002. Random matrix analysis is carried out using daily returns of 70 stocks for several time windows of 85 days in 2001 to (i) do a brief comparative analysis with statistics of eigenvalues and eigenvectors of the matrix C of correlations between price fluctuations, in time regimes of different volatilities. While a bulk of eigenvalues falls within RMT bounds in all the time periods, we see that the largest (deviating) eigenvalue correlates well with the volatility of the index, the corresponding eigenvector clearly shows a shift in the distribution of its components from volatile to less volatile periods and verifies the qualitative association between participation and volatility (ii) observe that the Inverse participation ratio for the 'last' eigenvector is sensitive to market fluctuations (the two quantities are observed to anti correlate significantly) (iii) set up a variability index, V whose temporal evolution is found to be significantly correlated with the volatility of the overall market index. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('physics/0512169v1-abstract-full').style.display = 'none'; document.getElementById('physics/0512169v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 19 December, 2005; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2005. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">33 Pages, 19 Figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/physics/0307051">arXiv:physics/0307051</a> <span> [<a href="https://arxiv.org/pdf/physics/0307051">pdf</a>, <a href="https://arxiv.org/ps/physics/0307051">ps</a>, <a href="https://arxiv.org/format/physics/0307051">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Biological Physics">physics.bio-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Computational Physics">physics.comp-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Biomolecules">q-bio.BM</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1016/S0006-3495(03)74647-5">10.1016/S0006-3495(03)74647-5 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Simulations of Oligomeric Intermediates in Prion Diseases </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Mobley%2C+D+L">David L. Mobley</a>, <a href="/search/physics?searchtype=author&query=Cox%2C+D+L">Daniel L. Cox</a>, <a href="/search/physics?searchtype=author&query=Singh%2C+R+R+P">Rajiv R. P. Singh</a>, <a href="/search/physics?searchtype=author&query=Kulkarni%2C+R+V">Rahul V. Kulkarni</a>, <a href="/search/physics?searchtype=author&query=Slepoy%2C+A">Alexander Slepoy</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="physics/0307051v1-abstract-short" style="display: inline;"> We extend our previous stochastic cellular automata based model for areal aggregation of prion proteins on neuronal surfaces. The new anisotropic model allow us to simulate both strong beta-sheet and weaker attachment bonds between proteins. Constraining binding directions allows us to generate aggregate structures with the hexagonal lattice symmetry found in recently observed in vitro experimen… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('physics/0307051v1-abstract-full').style.display = 'inline'; document.getElementById('physics/0307051v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="physics/0307051v1-abstract-full" style="display: none;"> We extend our previous stochastic cellular automata based model for areal aggregation of prion proteins on neuronal surfaces. The new anisotropic model allow us to simulate both strong beta-sheet and weaker attachment bonds between proteins. Constraining binding directions allows us to generate aggregate structures with the hexagonal lattice symmetry found in recently observed in vitro experiments. We argue that these constraints on rules may correspond to underlying steric constraints on the aggregation process. We find that monomer dominated growth of the areal aggregate is too slow to account for some observed doubling time-to-incubation time ratios inferred from data, and so consider aggregation dominated by relatively stable but non-infectious oligomeric intermediates. We compare a kinetic theory analysis of oligomeric aggregation to spatially explicit simulations of the process. We find that with suitable rules for misfolding of oligomers, possibly due to water exclusion by the surrounding aggregate, the resulting oligomeric aggregation model maps onto our previous monomer aggregation model. Therefore it can produce some of the same attractive features for the description of prion incubation time data. We propose experiments to test the oligomeric aggregation model. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('physics/0307051v1-abstract-full').style.display = 'none'; document.getElementById('physics/0307051v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 July, 2003; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2003. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">8 pages, 10 figures For larger versions of several figures, see http://asaph.ucdavis.edu/~dmobley and click on the prion paper link</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Biophys. J. 85:2213-2223 (Oct. 2003) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/cond-mat/0110606">arXiv:cond-mat/0110606</a> <span> [<a href="https://arxiv.org/pdf/cond-mat/0110606">pdf</a>, <a href="https://arxiv.org/ps/cond-mat/0110606">ps</a>, <a href="https://arxiv.org/format/cond-mat/0110606">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Condensed Matter">cond-mat</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Biological Physics">physics.bio-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Chemical Physics">physics.chem-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1063/1.1446023">10.1063/1.1446023 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Strong electron correlations in cobalt valence tautomers </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=LaBute%2C+M+X">M. X. LaBute</a>, <a href="/search/physics?searchtype=author&query=Kulkarni%2C+R+V">R. V. Kulkarni</a>, <a href="/search/physics?searchtype=author&query=Endres%2C+R+G">R. G. Endres</a>, <a href="/search/physics?searchtype=author&query=Cox%2C+D+L">D. L. Cox</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="cond-mat/0110606v2-abstract-short" style="display: inline;"> We have examined cobalt based valence tautomer molecules such as Co(SQ)$_2$(phen) using density functional theory (DFT) and variational configuration interaction (VCI) approaches based upon a model Hamiltonian. Our DFT results extend earlier work by finding a reduced total energy gap (order 0.6 eV) between high temperature and low temperature states when we fully relax the coordinates (relative… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('cond-mat/0110606v2-abstract-full').style.display = 'inline'; document.getElementById('cond-mat/0110606v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="cond-mat/0110606v2-abstract-full" style="display: none;"> We have examined cobalt based valence tautomer molecules such as Co(SQ)$_2$(phen) using density functional theory (DFT) and variational configuration interaction (VCI) approaches based upon a model Hamiltonian. Our DFT results extend earlier work by finding a reduced total energy gap (order 0.6 eV) between high temperature and low temperature states when we fully relax the coordinates (relative to experimental ones). Futhermore we demonstrate that the charge transfer picture based upon formal valence arguments succeeds qualitatively while failing quantitatively due to strong covalency between the Co 3$d$ orbitals and ligand $p$ orbitals. With the VCI approach, we argue that the high temperature, high spin phase is strongly mixed valent, with about 30 % admixture of Co(III) into the predominantly Co(II) ground state. We confirm this mixed valence through a fit to the XANES spectra. Moreover, the strong electron correlations of the mixed valent phase provide an energy lowering of about 0.2-0.3 eV of the high temperature phase relative to the low temperature one. Finally, we use the domain model to account for the extraordinarily large entropy and enthalpy values associated with the transition. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('cond-mat/0110606v2-abstract-full').style.display = 'none'; document.getElementById('cond-mat/0110606v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 16 January, 2002; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 29 October, 2001; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2001. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">10 pages, 4 figures, submitted to J. Chem. Phys</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/cond-mat/0110530">arXiv:cond-mat/0110530</a> <span> [<a href="https://arxiv.org/pdf/cond-mat/0110530">pdf</a>, <a href="https://arxiv.org/ps/cond-mat/0110530">ps</a>, <a href="https://arxiv.org/format/cond-mat/0110530">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Condensed Matter">cond-mat</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Biological Physics">physics.bio-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantitative Biology">q-bio</span> </div> </div> <p class="title is-5 mathjax"> Theoretical modeling of prion disease incubation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Kulkarni%2C+R+V">R. V. Kulkarni</a>, <a href="/search/physics?searchtype=author&query=Slepoy%2C+A">A. Slepoy</a>, <a href="/search/physics?searchtype=author&query=Singh%2C+R+R+P">R. R. P. Singh</a>, <a href="/search/physics?searchtype=author&query=Cox%2C+D+L">D. L. Cox</a>, <a href="/search/physics?searchtype=author&query=Mobley%2C+D">D. Mobley</a>, <a href="/search/physics?searchtype=author&query=P%C3%A1zm%C3%A1ndi%2C+F">F. P谩zm谩ndi</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="cond-mat/0110530v3-abstract-short" style="display: inline;"> We present a theory for the laboratory and epidemiological data for incubation times in infectious prion diseases. The central feature of our model is that slow growth of misfolded protein-aggregates from small initial seeds controls the `latent' or `lag' phase, whereas aggregate-fissioning and subsequent spreading leads to an exponential growth or doubling phase. Such a general framework can ac… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('cond-mat/0110530v3-abstract-full').style.display = 'inline'; document.getElementById('cond-mat/0110530v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="cond-mat/0110530v3-abstract-full" style="display: none;"> We present a theory for the laboratory and epidemiological data for incubation times in infectious prion diseases. The central feature of our model is that slow growth of misfolded protein-aggregates from small initial seeds controls the `latent' or `lag' phase, whereas aggregate-fissioning and subsequent spreading leads to an exponential growth or doubling phase. Such a general framework can account for many features of prion diseases including the striking reproducibility of incubation times when high doses are inoculated into lab animals. Broad incubation time distributions arise for low infectious dose, while our calculated distributions narrow to sharply defined onset times with increased dose. We apply our distributions to epidemiological vCJD data and extract estimates of incubation times. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('cond-mat/0110530v3-abstract-full').style.display = 'none'; document.getElementById('cond-mat/0110530v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 23 July, 2002; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 24 October, 2001; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2001. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">title changed, significantly revised and expanded with new sections, added author, 11 pages, 4 figures</span> </p> </li> </ol> <div class="is-hidden-tablet">  <span class="help" 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