Search

Alternation in various properties of n-alkanes (CnH2n+2) as a function of carbon content (n) is termed odd-even effect. Here, we report a comprehensive molecular dynamics simulation study on n-alkane systems carried out with n ranging between 3 (propane) and 8 (octane), examining the odd-even effect in melting point, density, intramolecular conformational ordering, translational and rotational motion. We observe an odd-even alternation in these properties, but with heptane (n = 7) exhibiting anomalous behavior for all except conformational ordering. Our simulations also show the presence of odd-even behavior in rotational and translational dynamics, below and above the melting point, respectively. The results highlight the role of both molecular shape and the variation in density and their interplay in the origins of the odd-even effect., Comment: 22 pages, first 16 constituting the main, followed by 6 more of supplementary material. 5 figures and 1 Table in the main, 6 figures and 1 Table in the supplementary material

Glycans are one of the most widely investigated biomolecules, due to their roles in numerous vital biological processes. This involvement makes it critical to understand their structure-function relationships. Few system-independent, LC-MS/MS (Liquid chromatography tandem mass spectrometry) based studies have been developed with this particular goal, however. When studied, the employed methods generally rely on normalized retention times as well as m/z - mass to charge ratio of an ion values. Due to these limitations, there is need for quantitative characterization methods which can be used independently of m/z values, thus utilizing only normalized retention times. As such, the primary goal of this article is to construct an LC-MS/MS based classification of the permethylated glycans derived from standard glycoproteins and human blood serum, using a Glucose Unit Index (GUI) as the reference frame in the space of compound parameters. For the reference frame we develop a closed-form analytic formula, which is obtained from the Green's function of a relevant convection-diffusion-absorption equation used to model composite material transport. The aforementioned equation is derived from an Einstein-Brownian motion paradigm, which provides a physical interpretation of the time-dependence at the point of observation for molecular transport in the experiment. The necessary coefficients are determined via a data-driven learning procedure. The methodology is presented in an abstract manner which allows for immediate application to related physical and chemical processes. Results employing the proposed classification method are validated via comparison with experimental mass spectrometer data., Comment: 24 pages, 7 figures

In this paper, the coherence between speech and noise signals is used to obtain a Speech Enhancement (SE) gain function, in combination with a Super Gaussian Joint Maximum a Posteriori (SGJMAP) single microphone SE gain function. The proposed SE method can be implemented on a smartphone that works as an assistive device to hearing aids. Although coherence SE gain function suppresses the background noise well, it distorts the speech. In contrary, SE using SGJMAP improves speech quality with additional musical noise, which we contain by using a post filter. The weighted union of these two gain functions strikes a balance between noise suppression and speech distortion. A 'weighting' parameter is introduced in the derived gain function to allow the smartphone user to control the weighting factor based on different background noise and their comfort level of hearing. Objective and subjective measures of the proposed method show effective improvement in comparison to standard techniques considered in this paper for several noisy conditions at signal to noise ratio levels of -5 dB, 0 dB and 5 dB., Comment: 4 pages, 3 figures

We have investigated the effect of molecular shape and charge asymmetry on the translation dynamics of confined hydrocarbon molecules having different shapes but similar kinetic diameters, inside ZSM-5 pores using molecular dynamics simulations. The mean square displacement of propane, acetonitrile, acetaldehyde, and acetone in ZSM-5 exhibit two different regimes - ballistic and diffusive/sub-diffusive. All the molecules except propane exhibit sub-diffusive motion at time scales greater than 1 ps. The intermediate scattering functions reveal that there is a considerable rotational- translational coupling in the motion of all the molecules, due to the strong geometrical restriction imposed by ZSM-5. Overall the difference in shape and asymmetry in charge imposes severe restriction inside the ZSM-5 channels for all the molecules to different extents. Further, the behavior of molecules confined in ZSM-5 in the present study, quantified wherever possible, is compared to their behavior in bulk or in other porous media reported in literature., Comment: 10 Pages, 10 Figures

We develop a FORTRAN code to compute fluctuations in atomic condensates (FACt) by solving the Bogoliubov-de Gennes (BdG) equations for two component Bose-Einstein condensate (TBEC) in quasi two dimensions. The BdG equations are recast as matrix equations and solved self consistently. The code is suitable for handling quantum fluctuations as well as thermal fluctuations at temperatures below the critical point of Bose-Einstein condensation. The code is versatile, and the ground state density profile and low energy excitation modes obtained from the code can be easily adapted to compute different properties of TBECs -- ground state energy, overlap integral, quasi particle amplitudes of BdG spectrum, dispersion relation and structure factor and other related experimental observables., Comment: The manuscript contains 28 pages and 6 figures. The code including sample input file and README file can be found in a tar file 'hfb2d2s.tar' by clicking on the "other formats" in the paper download page

For past several decades, research efforts in population modelling has proven its efficacy in understanding the basic information about residential and commercial areas, as well as for the purposes of planning, development and improvement of the community as an eco-system. More or less, such efforts assume static nature of population distribution, in turn limited by the current ability to capture the dynamics of population change at a finer resolution of space and time. Fast forward today, more and more people are becoming mobile, traveling across borders impacting the nuts and bolts of our urban fabric. Unfortunately, our current efforts are being surpassed by the need to capture such transient population. It is becoming imperative to identify and define them, as well as measure their dynamics and interconnectedness. In this work, we intend to research urban population mobility patterns, gauge their transient nature, and extend our knowledge of their visited locations. We plan to achieve this by designing and developing novel methods and using VGI data that models and characterizes transient population dynamics.

Geospatial intelligence has traditionally relied on the use of archived and unvarying data for planning and exploration purposes. In consequence, the tools and methods that are architected to provide insight and generate projections only rely on such datasets. Albeit, if this approach has proven effective in several cases, such as land use identification and route mapping, it has severely restricted the ability of researchers to inculcate current information in their work. This approach is inadequate in scenarios requiring real-time information to act and to adjust in ever changing dynamic environments, such as evacuation and rescue missions. In this work, we propose PlanetSense, a platform for geospatial intelligence that is built to harness the existing power of archived data and add to that, the dynamics of real-time streams, seamlessly integrated with sophisticated data mining algorithms and analytics tools for generating operational intelligence on the fly. The platform has four main components - i. GeoData Cloud - a data architecture for storing and managing disparate datasets; ii. Mechanism to harvest real-time streaming data; iii. Data analytics framework; iv. Presentation and visualization through web interface and RESTful services. Using two case studies, we underpin the necessity of our platform in modeling ambient population and building occupancy at scale.

The US neutrino community gathered at the Workshop on the Intermediate Neutrino Program (WINP) at Brookhaven National Laboratory February 4-6, 2015 to explore opportunities in neutrino physics over the next five to ten years. Scientists from particle, astroparticle and nuclear physics participated in the workshop. The workshop examined promising opportunities for neutrino physics in the intermediate term, including possible new small to mid-scale experiments, US contributions to large experiments, upgrades to existing experiments, R&D plans and theory. The workshop was organized into two sets of parallel working group sessions, divided by physics topics and technology. Physics working groups covered topics on Sterile Neutrinos, Neutrino Mixing, Neutrino Interactions, Neutrino Properties and Astrophysical Neutrinos. Technology sessions were organized into Theory, Short-Baseline Accelerator Neutrinos, Reactor Neutrinos, Detector R&D and Source, Cyclotron and Meson Decay at Rest sessions.This report summarizes discussion and conclusions from the workshop., Comment: pdfLaTeX, 31 pages, 1 figure, minor modification to 0nuBB discussion

We show that the third Goldstone mode in the two-species condensate mixtures, which emerges at phase-separation, gets hardened when the confining potentials have separated trap centers. The {\em sandwich} type condensate density profiles, in this case, acquire a {\em side-by-side} density profile configuration. We use Hartree-Fock-Bogoliubov theory with Popov approximation to examine the mode evolution and density profiles for these phase transitions at $T=0$., Comment: 5 pages, 2 figures. Some part of the theory is common to arXiv:1307.5716 and arXiv:1405:6459, so that the article is self-contained for the benefit of the readers

Vortex reconnections plays an important role in the turbulent flows associated with the superfluids. To understand the dynamics, we examine the reconnections of vortex rings in the superfluids of dilute atomic gases confined in trapping potentials using Gross-Petaevskii equation. Furthermore we study the reconnection dynamics of coreless vortex rings, where one of the species can act as a tracer., Comment: 9 pages, Proceeding from International Conference On Complex Processes in Plasmas and Nonlinear Dynamical Systems, Gandhinagar, India (November 2012)

We study the dynamics of a single and a corotating vortex pair in a dipolar Bose-Einstein condensate in the framework of dissipative Gross-Pitaevskii equation. This simple model enables us to simulate the effect of finite temperature on the vortex dynamics. We study the effect of dipolar interactions on the dynamics of a single vortex in the presence of phenomenological dissipation. In the case of a corotating vortex pair, an initial asymmetry in the locations of the vortices can lead to different decay rates for the constituent vortices as is the case for the condensates interacting via pure contact interactions. We observe that the anisotropic interaction between the component vortices manifests itself as the perceptible difference in the trajectories traversed by the vortices in the condensate at finite temperatures., Comment: 8 pages, 7 figures

We study the merging and splitting of quasi-two-dimensional Bose-Einstein condensates with strong dipolar interactions. We observe that if the dipoles have a non-zero component in the plane of the condensate, the dynamics of merging or splitting along two orthogonal directions, parallel and perpendicular to the projection of dipoles on the plane of the condensate are different. The anisotropic merging and splitting of the condensate is a manifestation of the anisotropy of the roton-like mode in the dipolar system. The difference in dynamics disappears if the dipoles are oriented at right angles to the plane of the condensate as in this case the Bogoliubov dispersion, despite having roton-like features, is isotropic., Comment: 9 pages and 9 figures

Let g be a complex, semisimple Lie algebra, and Y_h(g) and U_q(Lg) the Yangian and quantum loop algebra of g. Assuming that h is not a rational number and that q=exp(i \pi h), we construct an equivalence between the finite-dimensional representations of U_q(Lg) and an explicit subcategory of those of Y_h(g) defined by choosing a branch of the logarithm. This equivalence is governed by the monodromy of the abelian additive difference equations defined by the commuting fields of Y_h(g). Our results are compatible with q-characters, and apply more generally to a symmetrisable Kac-Moody algebra g, in particular to affine Yangians and quantum toroidal algebras. In this generality, they yield an equivalence between the representations of Y_h(g) and U_q(Lg) whose restriction to g and U_q(g) respectively are integrable and in category O., Comment: Minor typos corrected. Final version. To appear in JAMS. 55 pages

We study the dynamics of a single and a pair of vortices in quasi two-dimensional Bose-Einstein condensates at finite temperatures. We use the stochastic Gross-Pitaevskii equation, which is the Langevin equation for the Bose-Einstein condensate, to this end. For a pair of vortices, we study the dynamics of both the vortex-vortex and vortex-antivortex pairs, which are generated by rotating the trap and moving the Gaussian obstacle potential, respectively. Due to thermal fluctuations, the constituent vortices are not symmetrically generated with respect to each other at finite temperatures. This initial asymmetry coupled with the presence of random thermal fluctuations in the system can lead to different decay rates for the component vortices of the pair, especially in the case of two corotating vortices., Comment: 8 pages, 10 figures

We show that the third Goldstone mode, which emerges in binary condensates at phase-separation, persists to higher inter-species interaction for density profiles where one component is surrounded on both sides by the other component. This is not the case with symmetry-broken density profiles where one species is to entirely to the left and the other is entirely to the right. We, then, use Hartree-Fock-Bogoliubov theory with Popov approximation to examine the mode evolution at $T\neq0$ and demonstrate the existence of mode bifurcation near the critical temperature. The Kohn mode, however, exhibits deviation from the natural frequency at finite temperatures after the phase separation. This is due to the exclusion of the non-condensate atoms in the dynamics.

We examine the generation and subsequent evolution of Rayleigh Taylor instability in anisotropic binary Bose-Einstein condensates. Considering a pancake-shaped geometry, to initiate the instability we tune the intraspecies interaction and analytically study the normal modes of the interface in elliptic cylindrical coordinates. The normal modes are then Mathieu functions and undergoes bifurcation at particular values of anisotropy and ratio of number of atoms. We find that the analytical estimates of the bifurcation parameters are in good agreement with the numerical results., Comment: 7 pages, 6 figures

We investigate the initiation and subsequent evolution of Crow instability in an inhomogeneous unitary Fermi gas using zero-temperature Galilei-invariant non-linear Schr\"odinger equation. Considering a cigar-shaped unitary Fermi gas, we generate the vortex-antivortex pair either by phase-imprinting or by moving a Gaussian obstacle potential. We observe that the Crow instability in a unitary Fermi gas leads to the decay of the vortex-antivortex pair into multiple vortex rings and ultimately into sound waves., Comment: 7 pages, 4 figures, Accepted for publication in Mod. Phys. Lett. B (MPLB)

We theoretically investigate the generation of the vortex dipoles in superfluid Fermi gas in the BCS limit. The vortex dipoles are generated in superfluid either by moving an obstacle above a critical speed or due to the decay of the shock waves obtained on the sudden mixing of two superfluid fragments. We observe that in pancake-shaped traps, the shock waves can lead to the formation of density ripples, which decay into vortex dipoles due to the onset of snake instability., Comment: Six pages, 7 Figures, Accepted for publication in Int. J. Mod. Phys. B (IJMPB)

In this paper, we compare various image background subtraction algorithms with the ground truth of cars counted. We have given a sample of thousand images, which are the snap shots of current traffic as records at various intersections and highways. We have also counted an approximate number of cars that are visible in these images. In order to ascertain the accuracy of algorithms to be used for the processing of million images, we compare them on many metrics that includes (i) Scalability (ii) Accuracy (iii) Processing time.

We provide a general scheme for proving $L^p$ estimates for certain bilinear Fourier restrictions outside the locally $L^2$ setting. As an application, we show how such estimates follow for the lacunary polygon. In contrast with prior approaches, our argument avoids any use of the Rubio de Francia Littlewood--Paley inequality.

We theoretically explore the annihilation of vortex dipoles, generated when an obstacle moves through an oblate Bose-Einstein condensate, and examine the energetics of the annihilation event. We show that the gray soliton, which results from the vortex dipole annihilation, is lower in energy than the vortex dipole. We also investigate the annihilation events numerically and observe that the annihilation occurs only when the vortex dipole overtakes the obstacle and comes closer than the coherence length. Furthermore, we find that the noise reduces the probability of annihilation events. This may explain the lack of annihilation events in experimental realizations., Comment: 8 pages and 9 figures

We study the motion of the Gaussian obstacle potential created by blue detuned laser beam through a phase-separated binary condensate in pancake-shaped traps. For the velocity of the obstacle above a critical velocity, we observe the generation of vortex dipoles in the outer component which can penetrate the inner component. This is equivalent to finite, although small, transport of outer component across the inner component. In the inner component, the same method can lead to the formation of coreless vortex dipoles., Comment: 12 pages, 9 figures

Vortex dipoles are generated when an obstacle moves through a superfluid. In case of phase-separated binary condensates, with appropriate interaction parameters in pan-cake shaped traps, we show that coreless vortex dipoles are created when a Gaussian obstacle beam traverses across them above a critical speed. As the obstacle passes through the inner component, it carries along a bubble of the outer component. Using Thomas-Fermi approximation, we show that phase-separated binary condensates can either support vortices with empty or filled cores. For time dependent obstacle potentials, ramped down in the present case, relative energy scales of the system influence the dynamical evolution of the binary condensate., Comment: 6 pages, 5 figures

Realistic modeling of vehicular mobility has been particularly challenging due to a lack of large libraries of measurements in the research community. In this paper we introduce a novel method for large-scale monitoring, analysis, and identification of spatio-temporal models for vehicular mobility using the freely available online webcams in cities across the globe. We collect vehicular mobility traces from 2,700 traffic webcams in 10 different cities for several months and generate a mobility dataset of 7.5 Terabytes consisting of 125 million of images. To the best of our knowl- edge, this is the largest data set ever used in such study. To process and analyze this data, we propose an efficient and scalable algorithm to estimate traffic density based on background image subtraction. Initial results show that at least 82% of individual cameras with less than 5% deviation from four cities follow Loglogistic distribution and also 94% cameras from Toronto follow gamma distribution. The aggregate results from each city also demonstrate that Log- Logistic and gamma distribution pass the KS-test with 95% confidence. Furthermore, many of the camera traces exhibit long range dependence, with self-similarity evident in the aggregates of traffic (per city). We believe our novel data collection method and dataset provide a much needed contribution to the research community for realistic modeling of vehicular networks and mobility.

Collective flow and balance energy in asymmetric heavy-ion collisions