arXiv subjects

Ajay Sharma

Publications and source records attributed to Ajay Sharma.

33 records · Page 2Linked to original sources

arXiv2023

Strategic Environmental Corporate Social Responsibility (ECSR) Certification and Endogenous Market Structure

This paper extends the findings of Liu et al. (2015, Strategic environmental corporate social responsibility in a differentiated duopoly market, Economics Letters), along two dimensions. First, we consider the case of endogenous market structure a la Vives and Singh (1984, Price and quantity competition in a differentiated duopoly, The Rand Journal of Economics). Second, we refine the ECSR certification standards in differentiated duopoly with rankings. We find that optimal ECSR certification standards by NGO are the highest in Bertrand competition, followed by mixed markets and the lowest in Cournot competition. Next, NGO certifier will set the ECSR standards below the optimal level. Also, we show that given the ECSR certification standards, there is a possibility of both price and quantity contracts choices by the firms in endogenous market structure.

econ.TH↗

arXiv2020

Constraining $f(R)$ model through spectral indices and reheating temperature

We investigate a form of $ f(R) = {R^{1+δ}}/{R_c^δ}$ and study the viability of the model for inflation in the Jordan and the Einstein frames. This model is further analysed by using the power spectrum indices of the inflation and the reheating temperature. During the inflationary evolution, the model predicts a value of $δ$ parameter very close to one ($δ=0.98$), while the reheating temperature $T_{re} \sim 10^{17}$ GeV at $δ=0.98$ is consistent with the standard approach to inflation and observations. We calculate the slow roll parameters for the minimally coupled scalar field within the framework of our model. It is found that the values of the scalar spectral index and tensor-to-scalar ratio are very close to the recent observational data, including those released by Planck 2018. We also show that the Jordan and the Einstein frames are equivalent when $δ\sim 1 $ by using the scalar spectral index, tensor-to-scalar ratio and reheating temperature.

gr-qc↗

arXiv2020

All Data Inclusive, Deep Learning Models to Predict Critical Events in the Medical Information Mart for Intensive Care III Database (MIMIC III)

Intensive care clinicians need reliable clinical practice tools to preempt unexpected critical events that might harm their patients in intensive care units (ICU), to pre-plan timely interventions, and to keep the patient's family well informed. The conventional statistical models are built by curating only a limited number of key variables, which means a vast unknown amount of potentially precious data remains unused. Deep learning models (DLMs) can be leveraged to learn from large complex datasets and construct predictive clinical tools. This retrospective study was performed using 42,818 hospital admissions involving 35,348 patients, which is a subset of the MIMIC-III dataset. Natural language processing (NLP) techniques were applied to build DLMs to predict in-hospital mortality (IHM) and length of stay >=7 days (LOS). Over 75 million events across multiple data sources were processed, resulting in over 355 million tokens. DLMs for predicting IHM using data from all sources (AS) and chart data (CS) achieved an AUC-ROC of 0.9178 and 0.9029, respectively, and PR-AUC of 0.6251 and 0.5701, respectively. DLMs for predicting LOS using AS and CS achieved an AUC-ROC of 0.8806 and 0.8642, respectively, and PR-AUC of 0.6821 and 0.6575, respectively. The observed AUC-ROC difference between models was found to be significant for both IHM and LOS at p=0.05. The observed PR-AUC difference between the models was found to be significant for IHM and statistically insignificant for LOS at p=0.05. In this study, deep learning models were constructed using data combined from a variety of sources in Electronic Health Records (EHRs) such as chart data, input and output events, laboratory values, microbiology events, procedures, notes, and prescriptions. It is possible to predict in-hospital mortality with much better confidence and higher reliability from models built using all sources of data.

cs.LG↗

arXiv2019

Weakly $I$-clean rings

In this article, we introduce the concept of weakly $I$-clean ring, for any ideal $I$ of a ring $R$. We show that, for an ideal $I$ of a ring $R$, $R$ is uniquely weakly $I$-clean if and only if $R/I$ is semi boolean and idempotents can be lifted uniquely weakly modulo $I$ if and only if for each $a\in R$, there exists a central idempotent $e\in R$ such that either $a-e\in I$ or $a+e\in I$ and $I$ is idempotent free. As a corollary, we characterize weakly $J$-clean ring. Also we study various properties of weakly $I$-clean ring.

math.RA↗

arXiv2019

Nil Clean Divisor Graph

In this article, we introduce a new graph theoretic structure associated with a finite commutative ring, called nil clean divisor graph. For a ring $R$, nil clean divisor graph is denoted by $G_N(R)$, where the vertex set is $\{x\in R\,:\, x\neq 0, \,\exists\, y(\neq 0, \neq x)\in R$ such that $xy$ is nil clean$\}$, two vertices $x$ and $y$ are adjacent if $xy$ is a nil clean element. We prove some interesting results of nil clean divisor graph of a ring.

math.RA↗

arXiv2018

Weak Nil Clean Ideal

As a generalization of nil clean ideal, we define weak nil clean ideal of a ring. An ideal $I$ of a ring $R$ is weak nil clean ideal if for any $x\in I$, either $x=e+n$ or $x=-e+n$, where $n$ is a nilpotent element and $e$ is an idempotent element of $R$. Some interesting properties of weak nil clean ideal and its relation with weak nil clean ring have been discussed.

math.RA↗

arXiv2018

Nilpotent Graph

In this article, we introduce the concept of nilpotent graph of a finite commutative ring. The set of all non nilpotent elements of a ring is taken as the vertex set and two vertices are adjacent if and only if their sum is nilpotent. We discuss some graph theoretic properties of nilpotent graph.

math.RA↗

arXiv2017

Nil Clean Ideal

Motivated by the concept of clean ideals, we introduce the notion of nil clean ideals of a ring. We define an ideal $I$ of a ring $R$ to be nil clean ideal if every element of $I$ can be written as a sum of an idempotent and a nilpotent element of $R$. In this article we discuss various properties of nil clean ideals.

math.RA↗

arXiv2017

Weakly nil clean graphs of rings

In this article, the concept of nil clean graph of a ring has been generalised to weakly nil clean graph of a ring and graph theoretic properties like girth, clique number, diameter and chromatic index of the graph have been studied for a finite commutative ring.

math.RA↗

arXiv2017

Weakly Clean Ideal

Motivated by the concept of clean ideals, we introduce the notion of weakly clean ideals. We define an ideal $I$ of a ring $R$ to be weakly clean ideal if for any $x\in I$, $x=u+e$ or $x=u-e$, where $u$ is a unit in $R$ and $e$ is an idempotent in $R$. We discuss various properties of weakly clean ideals.

math.RA↗

arXiv2017

Weakly $r$-clean rings and weakly $\star$-clean rings

Motivated by the concept of weakly clean rings, we introduce the concept of weakly $r$-clean rings. We define an element $x$ of a ring $R$ as weakly $r$-clean if it can be expressed as $x=r+e$ or $x=r-e$ where $e$ is an idempotent and $r$ is a regular element of $R$. If all the elements of $R$ are weakly $r$-clean then $R$ is called a weakly $r$-clean ring. We discuss some of its properties in this article. Also we generalise this concept of weakly $r$-clean ring to weakly $g(x)$-$r$-clean ring, where $g(x) \in C(R)[x]$ and $C(R)$ is the centre of the ring $R$. Finally we introduce the concept of weakly $\star$-clean and $\star$-$r$-clean ring and discuss some of their properties.

math.RA↗

arXiv2016

Fuzzy Commitment Scheme based on Reed Solomon Codes

The conventional commitment scheme requires both commitment string and a valid key for the sender to verify his commitment. Differ from the conventional commitment scheme; fuzzy commitment scheme accepts the key that is similar to the original key. The new opening key, not identical to the original key, differs from the initial key in some suitable metrics. The fuzziness in the fuzzy commitment scheme tolerate small amount of corruptions. The fuzzy commitment scheme based on the cryptographic hash functions suffers security imperfections. Thus, this paper combines the fuzzy commitment scheme with the Reed Solomon error correction codes, which are capable of correcting certain number of errors. As a result, Reed Solomon code proves better alternative for fuzzy commitment scheme than hash functions, as the Reed Solomon codes are more secure than the hashing techniques. Moreover, the Fuzzy Commitment Scheme based on Reed Solomon codes provides security at two levels that making it suitable for securing data. This paper explore the efficiency of executing fuzzy commitment scheme in conjunction with Reed Solomon code as a novel better alternative to the conventional commitment scheme.

cs.CR↗

arXiv2007

Non-resonant microwave absorption studies on MgB2 thin film

We report on the presence of weak links in the intermetallic superconductor MgB2 from the non-resonant microwave absorption (NRMA) studies on the MgB2 thin film. The strong low field signal, which is the characteristics of weak links and the presence of hysteresis, which arises due to flux trapping, are observed. The studies are carried out as a function of temperature, microwave power, magnitude of modulation field and the range of field scan. Presence of weak links is discussed in terms of increase in the oxygen content of grain boundaries in the thin film and because of disorder effects arises due to the aging of the sample. The pinning of flux lines with the changes in sweeping direction leads to hysteresis in the NRMA signal and shows the contribution of flux line motion in the power absorption.

cond-mat.supr-con↗

arXiv2005

Vitrification and Glass Transition of Water: Insights from Spin Probe ESR

Three long standing problems related to the physics of water viz, the possibility of vitrifying bulk water by rapid quenching, its glass transition, and the supposed impossibility of obtaining supercooled water between 150 and 233 K, the so-called 'no man's land'of its phase diagram, are studied using the highly sensitive technique of spin probe ESR. Our results suggest that water can indeed be vitrified by rapid quenching, it undergoes a glass transition at \~ 135 K, and the relaxation behavior studied using this method between 165 K and 233 K closely follows the predictions of the Adam-Gibbs model.

cond-mat.mtrl-sci↗

arXiv2005

Anomalous spin dynamics in charge ordered, 'two-electron' doped manganite Ca_0.9Ce_0.1MnO_3 : consequence of a spin-liquid phase?

The 'two-electron' doped rare earth mangnites Ca_1-x Ce_x MnO_3 (x = 0.1,0.2) are probed using resistivity, ac susceptibility and electron paramagnetic resonance (EPR) measurements across their respective charge ordering (CO) temperatures T_CO = 173 K and 250 K. The EPR 'g' factor and intensity as well as the transport and magnetic behaviours of the two compositions are qualitatively similar and are as expected for CO systems. However, the EPR linewidth, reflective of the spin dynamics, for x = 0.1, shows a strongly anomalous temperature dependence, decreasing with decreasing temperature below T_CO in contrast with the sample with x = 0.2 and other CO systems. Keeping in view the evidence for magnetic frustration in the system, we propose that the anomalous temperature dependence of the linewidth is the signature of the occurrence of a disorder driven spin liquid phase, present along with charge ordering.

cond-mat.str-el↗