arXiv subjects

Chandra Prakash

Publications and source records attributed to Chandra Prakash.

11 recordsLinked to original sources

arXiv2026

Canonical quantization of massive vector field in Schwarzschild black hole background

We perform a first-principles canonical quantization of a massive vector field, often referred to as the Proca field, in a Schwarzschild spacetime background. While scalar, fermionic, and electromagnetic fields are well studied in this context, the Proca field requires a more nuanced treatment because of the physical nature of the longitudinal polarization mode and the constrained dynamics of the field variables. By implementing the Dirac bracket formalism to treat the constraints inherent in the Proca action, we derive a consistent framework for the commutator algebra of creation and annihilation operators. Following this construction, we define the usual Boulware, Unruh, and Hartle-Hawking vacua. Using the Unruh vacuum, we derive and analyze the Hawking spectrum of the Proca field. Furthermore, we numerically evaluate the Proca condensate constructed from the two-point correlation function $\langle A_\mu(x) A_\nu(x') \rangle$, defined on all three vacuum states. We find that the condensate becomes significant near the boundary of the future horizon. Our results highlight the interplay among the different polarization modes and the significance of the Proca mass in quantum observables.

gr-qc↗

arXiv2026

Cosmological correlators from the Inflation end to CMB sky via reheating

We investigate the imprint of post-inflationary evolution on primordial cosmological correlators by relaxing the standard assumption of instantaneous reheating. We compute the power spectrum and bispectrum for a conformally coupled and non-minimally coupled ($\xi \neq \frac{1}{6},0$) scalar field with cubic self-interaction, across a finite reheating epoch characterized by an effective equation of state $w$, and reheating temperature $T_{\rm reh}$. We find that for a conformally coupled scalar field, the signatures of reheating, such as the modification to oscillatory features, are strictly confined to the subhorizon regime. On superhorizon scales, the correlators receive negligible corrections at leading order. In sharp contrast, for a non-minimally coupled field, we identify a distinct phenomenology where non-trivial values of $\xi$ and reheating equation of state $w$, can induce a tachyonic enhancement of the field modes on superhorizon scales. This enhancement modifies both the power spectrum and bispectrum, marking a sharp deviation from the instantaneous transition limit. Our results demonstrate that to the leading order while conformal coupling shields large-scale correlations from the expansion history, non-minimal coupling breaks this degeneracy and opens an observable window into the physics of reheating.

hep-th↗

arXiv2026

Non-Enzymatic Glucose sensing properties of NiO nanostructured flower decorated Exfoliated Graphite Electrodes

Nanostructured transition metal oxides (TMO) are extensively explored materials for non-enzymatic glucose sensors. TMOs such as Iron oxides( {\alpha}-Fe2O3, {\gamma}-Fe2O3, Fe3O4, etc.), NiO, CuO, Cr2O3, etc. have been utilized as electrocatalysts for glucose determination. Tremendous efforts have been put into identifying the impact of different morphologies of these materials on the glucose-sensing performance. The larger surface area of the flower and wire-shaped catalysts make them better performing amongst other morphologies. Interestingly, it is important to note that most of such studies are on standard Glassy Carbon electrodes. Further to enhance the Electrochemically active surface area (ECSA) of the electrode, Carbon nanomaterials such as reduced Graphene Oxide (r-GO) and Carbon Nanotubes (CNTs) are used as additives. Exfoliated Graphite paper electrodes offer better electrochemical characteristics than GCE electrodes due to their much larger ECSA. This study presents the non-enzymatic glucose sensing properties of NiO nanoflower-decorated Exfoliated Graphite electrodes. The amperometric detection of glucose shows a linear increase in current over a physiologically relevant wide range of 0-10 mM. The electrodes offer a better sensitivity of 304.12 microA per mM per cm square and a Limit Of Detection (LOD) of 100 microM. In addition, the electrodes showed high selectivity towards glucose in the presence of other interfering species such as Ascorbic acid, Fructose, Sucrose, and NaCl.

cond-mat.mtrl-sci↗

arXiv2026

Agentic AI Governance and Lifecycle Management in Healthcare

Healthcare organizations are beginning to embed agentic AI into routine workflows, including clinical documentation support and early-warning monitoring. As these capabilities diffuse across departments and vendors, health systems face agent sprawl, causing duplicated agents, unclear accountability, inconsistent controls, and tool permissions that persist beyond the original use case. Existing AI governance frameworks emphasize lifecycle risk management but provide limited guidance for the day-to-day operations of agent fleets. We propose a Unified Agent Lifecycle Management (UALM) blueprint derived from a rapid, practice-oriented synthesis of governance standards, agent security literature, and healthcare compliance requirements. UALM maps recurring gaps onto five control-plane layers: (1) an identity and persona registry, (2) orchestration and cross-domain mediation, (3) PHI-bounded context and memory, (4) runtime policy enforcement with kill-switch triggers, and (5) lifecycle management and decommissioning linked to credential revocation and audit logging. A companion maturity model supports staged adoption. UALM offers healthcare CIOs, CISOs, and clinical leaders an implementable pattern for audit-ready oversight that preserves local innovation and enables safer scaling across clinical and administrative domains.

cs.AI↗

arXiv2025

Momentum Space Correlation Functions in 2D Galilean Conformal Algebra

Galilean Conformal Algebra (GCA) arises as a controlled nonrelativistic limit of the relativistic conformal algebra. In this paper, we initiate the study of momentum space correlation functions in two-dimensional GCA. We derive and solve momentum space Ward identities to obtain two-point and three-point functions. However, relating them to position space correlation functions presents a challenge as Fourier transforms of the latter do not exist. This is resolved by analytically continuing the boost eigenvalues to imaginary values. In this regime, the Fourier transform of the position space two-point and three-point functions exist and match exactly with the momentum space two-point and three-point function obtained by solving the Ward identities.

hep-th↗

arXiv2025

Soft Pneumatic Grippers: Topology optimization, 3D-printing and Experimental validation

Typically, heuristic/trial-based approaches are used to design soft pneumatic grippers (SPGs). This paper presents a systematic topology optimization framework for developing SPGs. The design-dependent nature of actuating load is modeled using Darcy's law with an added drainage term. A 2D soft arm unit is then optimized as a compliant mechanism under pneumatic loading. To ensure the design is robust and manufacturable, the problem is formulated as a min-max optimization, where output deformations of blueprint and eroded designs are considered. A volume constraint is imposed on the blueprint part, while a strain-energy constraint is enforced on the eroded part. The Method of Moving Asymptotes is employed to solve optimization problems. The optimized 2D part is extruded suitably to generate a 3D unit. Ten such 3D units are assembled to create a gripper arm. Both the optimized 2D unit and the corresponding gripper arm outperform their conventional rectangular designs under pneumatic loading, demonstrating the efficacy of the proposed approach. The arms are fabricated using the SLA printing technique. Numerical and experimental results are compared at different pneumatic loads. Four 3D-printed arms are integrated with a supporting structure to form the SPG. The gripping action of the SPG is demonstrated on objects with different weights, sizes, structures, stiffnesses, and shapes.

cs.RO↗

arXiv2025

Efficient Memory Tiering in a Virtual Machine

Memory tiering is the norm to effectively tackle the increasing server memory total cost of ownership (TCO) and the growing data demands of modern data center workloads. However, the host-based state-of-the-art memory tiering solutions can be inefficient for a virtualized environment when (i) the frequently accessed data are scattered across the guest physical address space or (ii) the accesses to a huge page inside the guest are skewed due to a small number of subpages being hot. Scattered or skewed accesses make the whole huge page look hot in the host address space. This results in host selecting and placing sparsely accessed huge pages in near memory, wasting costly near memory resources. We propose a host-agnostic technique employed inside the guest that exploits the two-level address translation in a virtualized environment to consolidate the scattered and skewed accesses to a set of guest physical address ranges. Consolidation transforms sparsely hot huge pages to densely hot huge pages in the host address space context. As a consequence, host-based tiering solutions can place densely hot huge pages in near memory, improving near memory utilization. Our evaluation of our technique on standalone real-world benchmarks with state-of-the-art host-based tiering show 50-70% reduction in near memory consumption at similar performance levels, while evaluation at scale improves performance by 10-13% with similar memory TCO.

cs.OS↗

arXiv2023

Some Approximation Properties by Szász-P{ă}lt{ă}nea type Operators involving the Appell Polynomials of class $A^2$

This article contributes to the new summation of Szász operators with the help of Appell polynomials of class $A^{2}$. We verified Bohman-Korovkin's theorem and prove the convergence results like Lipschitz-type space, Voronvaskaja-type asymptotic formula, and modulus of continuity using the given operators. Furthermore, we have shown the weighted modulus of continuity and the derivative of bounded variation.

math.CA↗

arXiv2022

Mathematical problems in the Theory of ECO

A critical overview of the concepts that govern the principles of the Eternally Collapsing Object (ECO) is entailed in this article. The mathematical analysis will be dealt to conclude the proof required for the ECO paradigm is ad-hoc in nature at best. The first section details in rejecting black holes always considers the possibility of formation of trapped surfaces, so we will begin our work by looking into "non occurrence of trapped surfaces" then we analyze Dr. Mitra's indirect claim regarding how $ R = 0$ (inside black hole) could also be treated as another coordinate singularity. After this a detailed analysis on the claim that the mass of the Schwarzschild black hole being zero is in actuality a valid claim or not. The main aim of this article is address the core issue of whether black holes indeed do exist or is it a consequence of biases that circumvent common sense over the years. This article aims to bridge the gap between ECOs and black holes and if at all black holes do exist, which was vehemently denied by the person whose paper I am reviewing. The analysis presented here will show us, why ECOs are baseless and can not really be the solution to black hole problem.

gr-qc↗

arXiv2021

Explanatory Analysis and Rectification of the Pitfalls in COVID-19 Datasets

Since the onset of the COVID-19 pandemic in 2020, millions of people have succumbed to this deadly virus. Many attempts have been made to devise an automated method of testing that could detect the virus. Various researchers around the globe have proposed deep learning based methodologies to detect the COVID-19 using Chest X-Rays. However, questions have been raised on the presence of bias in the publicly available Chest X-Ray datasets which have been used by the majority of the researchers. In this paper, we propose a 2 staged methodology to address this topical issue. Two experiments have been conducted as a part of stage 1 of the methodology to exhibit the presence of bias in the datasets. Subsequently, an image segmentation, super-resolution and CNN based pipeline along with different image augmentation techniques have been proposed in stage 2 of the methodology to reduce the effect of bias. InceptionResNetV2 trained on Chest X-Ray images that were augmented with Histogram Equalization followed by Gamma Correction when passed through the pipeline proposed in stage 2, yielded a top accuracy of 90.47% for 3-class (Normal, Pneumonia, and COVID-19) classification task.

eess.IV↗

arXiv2020

Generalized Brick Wall Method for Stationary Axisymmetric Spacetimes

The microscopic origin of black hole entropy remains one of the central puzzles in quantum gravity. In this work, we investigate the statistical entropy of scalar fields propagating in stationary axisymmetric spacetimes using the thin-film modification of the 't Hooft brick wall method. We derive a generalized expression for the free energy of both superradiant and non-superradiant modes, expressed explicitly in terms of generic metric components. This unified formalism allows for a systematic evaluation of entropy across a diverse class of black holes without re-deriving the wave equation for each specific case. We validate our approach by recovering the Bekenstein-Hawking area law for the standard Kerr black hole. Subsequently, we extend the analysis to the Kerr-Newman-AdS geometry and, finally, to the novel case of a Kerr-Newman-AdS black hole surrounded by quintessence and a cloud of strings. Our results confirm that the area law holds even in the presence of these complex background matter fields, provided the cutoff parameter is appropriately renormalized.

gr-qc↗