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S. Jain

Publications and source records attributed to S. Jain.

At least 19 recordsLinked to original sources
arXiv2025

Midinfrared Semiconductor Photonics - A Roadmap

Semiconductor photonic devices operating in the midwave infrared (mid-IR, which we roughly define here as wavelengths spanning 3 to 14 microns) uniquely address a wide range of current practical needs. These include chemical sensing, environmental monitoring, industrial process control, medical diagnostics, thermal imaging, LIDAR, free space optical communication, and security monitoring. However, mid-IR device technologies are currently still works in progress that are generally much less mature than their near infrared and visible counterparts. Not only are most of the relevant materials more difficult to grow and process, but attainment of the desired optical device performance is often fundamentally more challenging. This Roadmap will review the leading applications for mid-IR optoelectronics, summarize the status and deficiencies of current device technologies, and then suggest possible roadmaps for improving and maturing the performance, manufacturability, and cost of each device type so the critical needs that are uniquely addressed by mid-IR photonics can be satisfied.

physics.optics↗
arXiv2024

The algebraic structure of hyperbolic graph braid groups

Genevois recently classified which graph braid groups on $\ge 3$ strands are word hyperbolic. In the $3$-strand case, he asked whether all such word hyperbolic groups are actually free; this reduced to checking two infinite classes of graphs: sun and pulsar graphs. We prove that $3$-strand braid groups of sun graphs are free. On the other hand, it was known to experts that $3$-strand braid groups of most pulsar graphs contain surface subgroups. We provide a simple proof of this and prove an additional structure theorem for these groups.

math.GR↗
arXiv2022

Spectral Clustering for Jet Reconstruction

We present a new approach to jet definition alternative to clustering methods, such as the anti-$k_T$ scheme, that exploit kinematic data directly. Instead the new method uses kinematic information to represent the particles in a multidimensional space, as in spectral clustering. After confirming its Infra-Red (IR) safety, we compare its performance in analysing $gg \rightarrow H_{125~\rm GeV} \rightarrow H_{40~\rm GeV}H_{40~\rm GeV} \rightarrow b\bar{b}b\bar{b}$, $gg \rightarrow H_{500~\rm GeV} \rightarrow H_{125~\rm GeV}H_{125~\rm GeV} \rightarrow b\bar{b}b\bar{b}$ and $gg, q\bar{q} \rightarrow t\bar{t} \rightarrow b\bar{b}W^+W^- \rightarrow b\bar{b}jjl\nu l$ events from Monte Carlo (MC) samples, specifically, in reconstructing the relevant final states, to that of the anti-$k_T$ algorithm. Finally, we show that the results for spectral clustering are obtained without any change in the parameter settings of the algorithm, unlike the anti-$k_T$ case, which requires the cone size to be adjusted to the physics process under study.

hep-ph↗
arXiv2020

Les Houches 2019 Physics at TeV Colliders: New Physics Working Group Report

This report presents the activities of the `New Physics' working group for the `Physics at TeV Colliders' workshop (Les Houches, France, 10--28 June, 2019). These activities include studies of direct searches for new physics, approaches to exploit published data to constrain new physics, as well as the development of tools to further facilitate these investigations. Benefits of machine learning for both the search for new physics and the interpretation of these searches are also presented.

hep-ph↗
arXiv2018

WU-NEAT: A clinically validated, open- source MATLAB toolbox for limited-channel neonatal EEG analysis

Goal: Limited-channel EEG research in neonates is hindered by lack of open, accessible analytic tools. To overcome this limitation, we have created the Washington University- Neonatal EEG Analysis Toolbox (WU-NEAT), containing two of the most commonly used tools, provided in an open-source, clinically-validated package running within MATLAB. Methods: The first algorithm is the amplitude-integrated EEG (aEEG), which is generated by filtering, rectifying and time-compressing the original EEG recording, with subsequent semi-logarithmic display. The second algorithm is the spectral edge frequency (SEF), calculated as the critical frequency below which a user- defined proportion of the EEG spectral power is located. The aEEG algorithm was validated by three experienced reviewers. Reviewers evaluated aEEG recordings of fourteen preterm/term infants, displayed twice in random order, once using a reference algorithm and again using the WU-NEAT aEEG algorithm. Using standard methodology, reviewers assigned a background pattern classification. Inter/intra-rater reliability was assessed. For the SEF, calculations were made using the same fourteen recordings, first with the reference and then with the WU-NEAT algorithm. Results were compared using Pearson's correlation coefficient. Results: For the aEEG algorithm, intra- and inter-rater reliability was 100% and 98%, respectively. For the SEF, the mean (SD) Pearson correlation coefficient between algorithms was 0.96 (0.04). Conclusion: We have demonstrated a clinically-validated toolbox for generating the aEEG as well as calculating the SEF from EEG data. Open-source access will enable widespread use of common analytic algorithms which are device-independent and not subject to obsolescence, thereby facilitating future collaborative research in neonatal EEG.

q-bio.NC↗
arXiv2017

SiW ECAL for future $e^+e^-$ collider

Calorimeters with silicon detectors have many unique features and are proposed for several world-leading experiments. We discuss the tests of the first three 18x18 cm$^2$ layers segmented into 1024 pixels of the technological prototype of the silicon-tungsten electromagnetic calorimeter for a future $e^+e^-$ collider. The tests have beem performed in November 2015 at CERN SPS beam line.

physics.ins-det↗
arXiv2016

Generalization of Quadratic Manifolds for Reduced Order Modeling of Nonlinear Structural Dynamics

In this paper, a generalization of a quadratic manifold approach for the reduction of geometrically nonlinear structural dynamics problems is presented. This generalization is constructed by a linearization of the static force with respect to the generalized coordinates, resulting in a shift of the quadratic behavior from the force to the manifold. In this framework, static derivatives emerge as natural extensions to modal derivatives for displacement fields other than the vibration modes, such as the Krylov subspace vectors. Here the dynamic problem is projected onto the tangent space of the quadratic manifold, allowing for a much less number of generalized coordinates compared to linear basis methods. The potential of the quadratic manifold approach is investigated in a numerical study, where several variations of the approach are compared on different examples, indicating a clear pattern where the proposed approach is applicable.

cs.CE↗
arXiv2016

Inference of internal stress in a cell monolayer

We combine traction force data with Bayesian inversion to obtain an absolute estimate of the internal stress field of a cell monolayer. The method, Bayesian inversion stress microscopy (BISM), is validated using numerical simulations performed in a wide range of conditions. It is robust to changes in each ingredient of the underlying statistical model. Importantly, its accuracy does not depend on the rheology of the tissue. We apply BISM to experimental traction force data measured in a narrow ring of cohesive epithelial cells, and check that the inferred stress field coincides with that obtained by direct spatial integration of the traction force data in this quasi-one-dimensional geometry.

q-bio.QM↗
arXiv2014

Magneto-Seebeck effect in spin-valve with in-plane thermal gradient

We present measurements of magneto-Seebeck effect on a spin valve with in-plane thermal gradient. We measured open circuit voltage and short circuit current by applying a temperature gradient across a spin valve stack, where one of the ferromagnetic layers is pinned. We found a clear hysteresis in these two quantities as a function of magnetic field. From these measurements, the magneto-Seebeck effect was found to be 0.82%.

cond-mat.mes-hall↗
arXiv2008

Double Power Law Decay of the Persistence in Financial Markets

The persistence phenomenon is studied in the Japanese financial market by using a novel mapping of the time evolution of the values of shares quoted on the Nikkei Index onto Ising spins. The method is applied to historical end of day data from the Japanese stock market during 2002. By studying the time dependence of the spins, we find clear evidence for a double-power law decay of the proportion of shares that remain either above or below ` starting\rq\ values chosen at random. The results are consistent with a recent analysis of the data from the London FTSE100 market. The slopes of the power-laws are also in agreement. We estimate a long time persistence exponent for the underlying Japanese financial market to be 0.5.

q-fin.ST↗
arXiv2007

Persistence in a Random Bond Ising Model of Socio-Econo Dynamics

We study the persistence phenomenon in a socio-econo dynamics model using computer simulations at a finite temperature on hypercubic lattices in dimensions up to 5. The model includes a ` social\rq local field which contains the magnetization at time $t$. The nearest neighbour quenched interactions are drawn from a binary distribution which is a function of the bond concentration, $p$. The decay of the persistence probability in the model depends on both the spatial dimension and $p$. We find no evidence of ` blocking\rq in this model. We also discuss the implications of our results for possible applications in the social and economic fields. It is suggested that the absence, or otherwise, of blocking could be used as a criterion to decide on the validity of a given model in different scenarios.

q-fin.GN↗
arXiv2007

Tevatron-for-LHC Report: Top and Electroweak Physics

The top quark and electroweak bosons (W and Z) represent the most massive fundamental particles yet discovered, and as such refer directly to the Standard Model's greatest remaining mystery: the mechanism by which all particles gained mass. This report summarizes the work done within the top-ew group of the Tevatron-for-LHC workshop. It represents a collection of both Tevatron results, and LHC predictions. The hope is that by considering and comparing both machines, the LHC program can be improved and aided by knowledge from the Tevatron, and that particle physics as a whole can be enriched. The report includes measurements of the top quark mass, searches for single top quark production, and physics of the electroweak bosons at hadron colliders.

hep-ph↗
arXiv2006

Persistence in Random Bond Ising Models of a Socio-Econo Dynamics in High Dimensions

We study the persistence phenomenon in a socio-econo dynamics model using computer simulations at a finite temperature on hypercubic lattices in dimensions up to 5. The model includes a ` social\rq local field which contains the magnetization at time $t$. The nearest neighbour quenched interactions are drawn from a binary distribution which is a function of the bond concentration, $p$. The decay of the persistence probability in the model depends on both the spatial dimension and $p$. We find no evidence of ` blocking\rq in this model. We also discuss the implications of our results for applications in the social and economic fields.

physics.soc-ph↗
arXiv2006

Financial Markets and Persistence

Persistence is studied in a financial context by mapping the time evolution of the values of the shares quoted on the London Financial Times Stock Exchange 100 index (FTSE 100) onto Ising spins. By following the time dependence of the spins, we find evidence for power law decay of the proportion of shares that remain either above or below their ` starting\rq values. As a result, we estimate a persistence exponent for the underlying financial market to be $θ_f\sim 0.5$.

physics.soc-ph↗
arXiv2005

Persistence and the Random Bond Ising Model in Two Dimensions

We study the zero-temperature persistence phenomenon in the random bond $\pm J$ Ising model on a square lattice via extensive numerical simulations. We find strong evidence for ` blocking\rq regardless of the amount disorder present in the system. The fraction of spins which {\it never} flips displays interesting non-monotonic, double-humped behaviour as the concentration of ferromagnetic bonds $p$ is varied from zero to one. The peak is identified with the onset of the zero-temperature spin glass transition in the model. The residual persistence is found to decay algebraically and the persistence exponent $θ(p)\approx 0.9$ over the range $0.1\le p\le 0.9$. Our results are completely consistent with the result of Gandolfi, Newman and Stein for infinite systems that this model has ` mixed\rq behaviour, namely positive fractions of spins that flip finitely and infinitely often, respectively. [Gandolfi, Newman and Stein, Commun. Math. Phys. {\bf 214} 373, (2000).]

cond-mat.dis-nn↗
arXiv2000

Scaling and Persistence in the Two-Dimensional Ising Model

The spatial distribution of persistent spins at zero-temperature in the pure two-dimensional Ising model is investigated numerically. A persistence correlation length, $ξ(t)\sim t^Z$ is identified such that for length scales $r<<ξ(t)$ the persistent spins form a fractal with dimension $d_f$; for length scales $r>>ξ(t)$ the distribution of persistent spins is homogeneous. The zero-temperature persistence exponent, $θ$, is found to satisfy the scaling relation $θ= Z(2-d_f)$ with $θ=0.209\pm 0.002, Z=1/2$ and $d_f\sim 1.58$.

cond-mat.stat-mech↗