arXiv subjects

Rajesh Kumar

Publications and source records attributed to Rajesh Kumar.

At least 127 records · Page 7Linked to original sources

arXiv2021

$η$ mesons in hot magnetized nuclear matter

The $ηN$ interactions are investigated in the hot magnetized asymmetric nuclear matter using chiral SU(3) model and chiral perturbation theory (ChPT). In the chiral model, the in-medium properties of $η$-meson are calculated by the medium modified scalar densities under the influence of an external magnetic field. Further, in the combined approach of chiral model and ChPT, off-shell contributions of $ηN$ interactions are evaluated from the ChPT effective $ηN$ Lagrangian, and the in-medium effect of scalar densities are incorporated from the chiral SU(3) model. We observe a significant effect of magnetic field on the in-medium mass and optical potential of $η$ meson. We observe a deeper mass-shift in the combined approach of ChPT and chiral model compared to the effect of solo chiral SU(3) model. In both approaches, no additional mass-shift is observed due to the uncharged nature of $η$ mesons in the presence of magnetic field.

nucl-th↗

arXiv2020

Treadmill Assisted Gait Spoofing (TAGS): An Emerging Threat to wearable Sensor-based Gait Authentication

In this work, we examine the impact of Treadmill Assisted Gait Spoofing (TAGS) on Wearable Sensor-based Gait Authentication (WSGait). We consider more realistic implementation and deployment scenarios than the previous study, which focused only on the accelerometer sensor and a fixed set of features. Specifically, we consider the situations in which the implementation of WSGait could be using one or more sensors embedded into modern smartphones. Besides, it could be using different sets of features or different classification algorithms, or both. Despite the use of a variety of sensors, feature sets (ranked by mutual information), and six different classification algorithms, TAGS was able to increase the average False Accept Rate (FAR) from 4% to 26%. Such a considerable increase in the average FAR, especially under the stringent implementation and deployment scenarios considered in this study, calls for a further investigation into the design of evaluations of WSGait before its deployment for public use.

cs.CR↗

arXiv2020

Blockchain-Federated-Learning and Deep Learning Models for COVID-19 detection using CT Imaging

With the increase of COVID-19 cases worldwide, an effective way is required to diagnose COVID-19 patients. The primary problem in diagnosing COVID-19 patients is the shortage and reliability of testing kits, due to the quick spread of the virus, medical practitioners are facing difficulty identifying the positive cases. The second real-world problem is to share the data among the hospitals globally while keeping in view the privacy concerns of the organizations. Building a collaborative model and preserving privacy are major concerns for training a global deep learning model. This paper proposes a framework that collects a small amount of data from different sources (various hospitals) and trains a global deep learning model using blockchain based federated learning. Blockchain technology authenticates the data and federated learning trains the model globally while preserving the privacy of the organization. First, we propose a data normalization technique that deals with the heterogeneity of data as the data is gathered from different hospitals having different kinds of CT scanners. Secondly, we use Capsule Network-based segmentation and classification to detect COVID-19 patients. Thirdly, we design a method that can collaboratively train a global model using blockchain technology with federated learning while preserving privacy. Additionally, we collected real-life COVID-19 patients data, which is, open to the research community. The proposed framework can utilize up-to-date data which improves the recognition of computed tomography (CT) images. Finally, our results demonstrate a better performance to detect COVID-19 patients.

eess.IV↗

arXiv2020

A method to predict location of non-coup brain injuries

Brain injuries are a major reason for mortality and morbidity following trauma in sports, work and traffic. Apart from the trauma at the site of impact (coup injury), other regions of the brain remote from the impact locations (non-coup) are commonly affected. We show that a screw theory-based method can be used to account for the combined effect of head rotational and linear accelerations in causing brain injuries. A scalar measure obtained from the inner product of the motion screw and the impact screw is shown to be a predictor of the severity and the location of non-coup brain injuries under an impact. The predictions are consistent with head impact experiments conducted with non-human primates. The methodology is proved using finite element simulations and already published experimental results

q-bio.QM↗

arXiv2020

$η$ mesons in hot and dense asymmetric nuclear matter

We study the $ηN$ interactions in the hot and dense isospin asymmetric nuclear matter using two different approaches. In the first approach, the in-medium mass and optical potential of $η$-meson have been calculated in the chiral SU(3) model, considering the effect of explicit symmetry breaking term and range terms in the $ηN$ interaction Lagrangian density. In the second scenario, the conjunction of chiral perturbation theory and chiral SU(3) model is employed. In this case, the next-to-leading order $ηN$ interactions are evaluated from the chiral perturbation theory (ChPT), and the in-medium contribution of scalar densities are taken as input from chiral SU(3) model. We observe a larger negative mass-shift in the ChPT+chiral model approach compared to the chiral SU(3) model alone as a function of nuclear density. Moreover, the increase in the asymmetry and temperature cause a decrease in the magnitude of mass-shift. We have also studied the impact of $ηN$ scattering length $a^{ηN}$ on the $η$ meson mass $m^*_η$ and observed that the $m^*_η$ decrease more for increasing the value of scattering length.

nucl-th↗

arXiv2020

Touchless Typing Using Head Movement-based Gestures

In this paper, we propose a novel touchless typing interface that makes use of an on-screen QWERTY keyboard and a smartphone camera. The keyboard was divided into nine color-coded clusters. The user moved their head toward clusters, which contained the letters that they wanted to type. A front-facing smartphone camera recorded the head movements. A bidirectional GRU based model which used pre-trained embedding rich in head pose features was employed to translate the recordings into cluster sequences. The model achieved an accuracy of 96.78% and 86.81% under intra- and inter-user scenarios, respectively, over a dataset of 2234 video sequences collected from 22 users.

cs.HC↗

arXiv2020

On the Inference of Soft Biometrics from Typing Patterns Collected in a Multi-device Environment

In this paper, we study the inference of gender, major/minor (computer science, non-computer science), typing style, age, and height from the typing patterns collected from 117 individuals in a multi-device environment. The inference of the first three identifiers was considered as classification tasks, while the rest as regression tasks. For classification tasks, we benchmark the performance of six classical machine learning (ML) and four deep learning (DL) classifiers. On the other hand, for regression tasks, we evaluated three ML and four DL-based regressors. The overall experiment consisted of two text-entry (free and fixed) and four device (Desktop, Tablet, Phone, and Combined) configurations. The best arrangements achieved accuracies of 96.15%, 93.02%, and 87.80% for typing style, gender, and major/minor, respectively, and mean absolute errors of 1.77 years and 2.65 inches for age and height, respectively. The results are promising considering the variety of application scenarios that we have listed in this work.

cs.CV↗

arXiv2020

Dynamical model of expansion free dissipative perfect fluids in general relativity

This paper deals with the spherically symmetric self-gravitating star which is considered to be expansion free dissipative perfect fluids distribution. Some recent research reveals that expansion free dynamical star must be accelerating and dissipating. We adopted some conjectures to obtain the analytical solution for the dynamical model of such stars. Firstly, it has shown that density of dynamical star is homogeneous and \Lamada-dominated under quasi-static diffusion approximation. Secondly, the self-similar solution is also discussed to describe the dynamical model.

gr-qc↗

arXiv2020

Dynamics of expansion free self gravitating cylindrically symmetric radiating star

The present work deals with the dynamics of radiating star which is considered to be expansion free cylindrical symmetric dust dissipative fluids. Several treatments are adopted for the description of geometrical and physical features of such stars. Firstly, it is shown that, the dynamical star does not permit the streaming out limit and diffusion approximation and also proved that acceleration and dissipation are necessary for its dynamical evolution. It has also shown that, a static expansion free cylinder must be non-radiating. Secondly, the existence of cavity model and self-similar solution for the such dynamical star are also investigated.

gr-qc↗

arXiv2020

$ϕ$ meson mass and decay width in strange hadronic matter

The in-medium mass and decay width of the $ϕ$ meson in the hot asymmetric strange hadronic matter are calculated using an effective Lagrangian approach for $ϕ$ $K\bar K$ interaction. The in-medium contributions of $K \bar K$ loop to the $ϕ$ meson self-energy are computed by the medium modified kaon and antikaon mass which is evaluated using the chiral SU(3) model. To deal with the ultraviolet divergence, we regularize the loop integral of self-energy with a dipole form factor, and present the results for cut-off mass, $Λ_c$=3 GeV. In chiral model calculations, for strange matter, we find that the mass of kaons and antikaons decreases with the increase in baryonic density whereas the finite temperature causes an increase in the mass. We observed that the in-medium $ϕ$ meson mass decreases slowly with baryonic density whereas the decay width increases rapidly. The results in the present investigation support result in the literature which indicate a small downward shift in mass and a large broadening in the decay width. In the asymmetric strange hadronic matter, the study of the $ϕ$ mesons can be relevant for the compressed strange baryonic matter and experimental observables such as dilepton spectra which can result from the experiments in the future FAIR facility at GSI.

hep-ph↗

arXiv2020

Malignancy Induced Subtle Perturbation Sensitive Raman Scattering for Glioma Detection and Grading

Subtle changes in Raman spectral line-shape have been observed from malignant human brain cells and its possibility for being used in detection and grading of Glioma has been explored here. The latter has been developed as a result of the fact that the width of the Raman spectra is more sensitive, as compared to the peak position, to the brain tumors. The perturbations induced by the cell-modification, as a consequence to the cancerous growth, may be responsible for the widths variation in the Raman spectrum due to vibrational lifetime alteration enforced at the molecular levels. A consistent cancer induced effect on the spectral width has been observed for three different brain cells Raman modes at different frequencies . Raman spectral analysis reveals that for cancerous cells, the FWHM varies up to 35 % in comparison with the healthy cells. It has been established how a careful analysis of Raman spectra can help in easy detection of brain tumors. The methodology has been validated by studying the effect of similar microscopic perturbations, e.g, Fano coupling and quantum size effects, on different Raman spectral parameters which also reveals Raman width to be the most sensitive parameter.

physics.app-ph↗

arXiv2020

Uniformly Distributed Fe$_2$O$_3$ Nanoparticles Thin Films Synthesized by Spray Pyrolysis

Thin films of uniformly distributed Fe2O3 nanoparticles have been prepared on single crystal silicon and glass substrates by a spray pyrolysis technique in a single step using a mixture of water and ferrocene dissolved in xylene. The size distribution of nanoparticles is found to be in the range of 20 nm to 30 nm. The films have been characterized by X-ray diffraction, scanning electron microscopy and Raman spectroscopy techniques. The uniformity of the grown film was evident from the electron microscopic images on both the substrates. The crystallinity and band gap were investigated using X-ray diffraction and absorption spectroscopy respectively. Raman measurements of the prepared films have been carried out using two excitation wavelengths of 633 nm and 785 nm to investigate the depth of homogeneity of the films. The wavelength dependent Raman measurements reveal that the film is uniform across the thickness of the film on both the substrates.

physics.app-ph↗

arXiv2020

Heavy vector and axial-vector $D$ mesons in hot magnetized asymmetric nuclear matter

We observed the impact of finite magnetic field on the in-medium mass and decay constant of isospin averaged vector $D^*(D^{*^+},D^{*^0})$ and axial-vector $D_1(D^+_1, D^0_1)$ mesons. The quark and gluon condensates of the nuclear medium at finite magnetic field, temperature, isospin asymmetry, and density have been obtained by the meson exchange scalar fields within the chiral SU(3) model. The medium attributes modify the scalar and vector density of nuclear medium and this variation reflects in the in-medium mass and decay constant of spin 1 $D$ mesons. We calculate these observables by comparing the Operator Product Expansion (OPE) and the phenomenological side in the QCD Sum Rules. In the results, we observed a positive mass shift for charged vector and axial-vector $D$ mesons with respect to magnetic field. For neutral vector (axial-vector) $D$ mesons we observed negative (positive) mass shift as a function of magnetic field. In the application part, we calculate the in-medium partial decay width of the process $D^*_s$(2715/2860) $\rightarrow$ $D^* K$ by using $^3P_0$ model. The in-medium effects are incorporated through the in-medium masses of $D^*$ and $K$ mesons.

hep-ph↗

arXiv2020

Electrically reconfigurable silicon photonic filter enabled by embedded phase change material in microring resonator

We report a tunable optical filter based on phase change material $Ge_{2}Sb_{2}Te_{5}$ embedded in a silicon microring resonator. The high thermo-optic coefficient of $Ge_{2}Sb_{2}Te_{5}$ in amorphous phase enables tuning of resonance wavelength in broad range with a very small active volume. The low-loss indium-tin-oxide electrodes are employed to induce Joule heating in $Ge_{2}Sb_{2}Te_{5}$-Si active waveguide region. The electrically induced heating in the active region alters the effective refractive index of hybrid microring resulting in a wavelength tuning of 1.04 nm for an applied voltage of only 3V. The device exhibits high extinction ratios in the range of 20-41 dB and a compact active footprint 0.96 $μm^{2}$ only and is suitable for the large scale reconfigurable integrated photonic circuits.

physics.app-ph↗

arXiv2019

Mass-conserving weak solutions to the coagulation and collisional breakage equation with singular rates

In this article, the existence of mass-conserving solutions is investigated to the continuous coagulation and collisional breakage equation with singular coagulation kernels. Here, the probability distribution function attains singularity near the origin. The existence result is constructed by using both conservative and non-conservative truncations to the continuous coagulation and collisional breakage equation. The proof of the existence result relies on a classical weak L1 compactness method.

math.AP↗

arXiv2019

Size Dependent Sensitivity of Raman Line-Shape Parameters in Silicon Quantum Wire

A comparison of experimentally observed Raman scattering data with Raman line-shapes, generated theoretically using phonon confinement model, has been carried out to understand the sensitivity of different Raman spectral parameters on quantum confinement effect. Size dependent variations of full width at half maximum (FWHM), Raman peak position and asymmetry ratio have been analyzed to establish the sensitivity of their corresponding physical counterparts (phonon life time and dispersion) in confined systems. The comparison has been done in three different confinement regimes namely, weakly, moderately and strongly. Proper reasoning has been assigned for such a variation after validation of the theoretical analysis with the experimental observations. A moderately confined system was created by preparing 6 nm sized Si NSs using metal induced etching. An asymmetrically broadened and red-shifted Raman line-shape was observed which established that all the parameters get affected in moderately confined system. Sensitivity of a given Raman spectral parameters has been shown to be used as a tool to understand the role of external perturbations in a material.

cond-mat.mes-hall↗

arXiv2019

Symmetry in cancer networks identified: Proposal for multi-cancer biomarkers

One of the most challenging problems in biomedicine and genomics is the identification of disease biomarkers. In this study, proteomics data from seven major cancers were used to construct two weighted protein-protein interaction (PPI) networks i.e., one for the normal and another for the cancer conditions. We developed rigorous, yet mathematically simple, methodology based on the degeneracy at -1 eigenvalues to identify structural symmetry or motif structures in network. Utilising eigenvectors corresponding to degenerate eigenvalues in the weighted adjacency matrix, we identified structural symmetry in underlying weighted PPI networks constructed using seven cancer data. Functional assessment of proteins forming these structural symmetry exhibited the property of cancer hallmarks. Survival analysis refined further this protein list proposing BMI, MAPK11, DDIT4, CDKN2A, and FYN as putative multi-cancer biomarkers. The combined framework of networks and spectral graph theory developed here can be applied to identify symmetrical patterns in other disease networks to predict proteins as potential disease biomarkers.

q-bio.MN↗

arXiv2019

Mid-IR non-volatile silicon photonic switches using nanoscale Ge\textsubscript{2}Sb\textsubscript{2}Te\textsubscript{5} embedded in SOI waveguide

We propose and numerically analyze the hybrid Si-Ge\textsubscript{2}Sb\textsubscript{2}Te\textsubscript{5} strip waveguide switches for Mid-IR wavelength of 2.1 $μ$m. The switches investigated are one input-one output (on-off) type and one input-two outputs (directional coupler) type. The reversible transition between the switch states is achieved by inducing the phase transition from crystalline to amorphous and vice-versa by application of voltage pulses. The approach of embedding the nanoscale active material Ge\textsubscript{2}Sb\textsubscript{2}Te\textsubscript{5} within the Si waveguide is taken to enhance the interaction of light with the active region of the switches. The dimensions of the active regions of the switches are optimized to achieve low insertion loss, low switching energy, and high extinction ratio. In case of one input-one output switch, an extinction ratio of 33.79 dB along with an extremely low insertion loss of 0.52 dB is achieved using optimum Ge\textsubscript{2}Sb\textsubscript{2}Te\textsubscript{5} length of only 0.92 $μ$m. For one input-two outputs switch, an extinction ratio of 10.33 dB and 5.23 dB is obtained in cross and bar state respectively using an active length of 52 $μ$m. These values of extinction ratio, which are otherwise 18.59 dB and 8.33 dB respectively, are due to the necessity of doping the Si beneath the Ge\textsubscript{2}Sb\textsubscript{2}Te\textsubscript{5} to facilitate the electrical conduction needed for Joule heating. A suitable gap of 100 nm is kept between the active and passive arm of the directional coupler switch. The electro-thermal co-simulations confirm that phase change occurs in whole of the Ge\textsubscript{2}Sb\textsubscript{2}Te\textsubscript{5} region in both types of switches.

physics.app-ph↗