ScholarSphere: IITJ Research Insights Hub

A multipath channel impulse response (CIR) estimator is proposed by leveraging the simultaneous sparsity inherent in the multipath CIR across multiple measurement vectors (MMV) for asymmetrically clipped direct current-biased optical OFDM (ADO-OFDM) visible light communication (VLC) systems. A detailed multipath CIR model is formulated to characterize specular and diffuse optical reflections present in VLC channels. We begin by formulating the system model of the ADO-OFDM-VLC system. Following this, we briefly revisit the traditional channel estimation (CE) techniques, along with the class of compressive sensing (CS)-based CE schemes. Specifically, the FOCal Underdetermined System Solver (FOCUSS), its MMV-based extension (MFOCUSS), and orthogonal matching pursuit (OMP) algorithms are considered, as they effectively exploit the sparsity structure present in the multipath CIR of VLC channels. Furthermore, we introduce an enhanced estimation technique namely, the simultaneous sparse OMP (SOMP), which effectively utilizes the simultaneous sparsity observed in the delay-domain CIR across MMVs, particularly relevant to the non-line-of-sight (NLoS) components of the VLC channel. In addition, an advanced MMV-based Bayesian learning (MBL) framework is proposed to further reduce pilot overhead by exploiting both time and delay-domain sparsity of the CIR. For benchmarking, the Oracle-based minimum mean square error (O-MMSE), Oracle-based least square LS (O-LS), and the Bayesian Cramer-Rao lower bound (BCRLB) are utilized. Simulation results confirm that the proposed MMV-based MBL approach significantly outperforms conventional and existing CS-based techniques, including SOMP, MFOCUSS, and Bayesian learning (BL) methods, in terms of normalized mean square error (NMSE), pilot overhead, bit error rate (BER), and outage probability (OP). © 2025 IEEE. All rights reserved.

Introduction: Bone-anchored maxillary protraction (BAMP) is an effective therapeutic approach for managing developing skeletal Class III malocclusion. This study aimed to determine the stress distribution in the circum-maxillary sutures, temporomandibular articular disc and mandibular condyle, as well as the displacement of key craniofacial landmarks during BAMP. Methods: A three-dimensional linear finite element (FE) model of the skull, articular disc and anchor plate was developed. Using this model, Class III intermaxillary loads of 150 g, 250 g and 400 g were applied through anchorage plates at angulations of 10°, 20° and 30°. Stress distribution in the circum-maxillary sutures, articular disc and condylar head was evaluated. Additionally, displacement of the anterior nasal spine (ANS), posterior nasal spine (PNS), pogonion and condylion in the anteroposterior and vertical directions was assessed. Results: Increasing force magnitude and angulation resulted in greater maxillary displacement and elevated stresses at circummaxillary sutures. Von Mises and principal stress analyses demonstrated that moderate forces (150–250 g) produced favourable displacement with comparatively lower stress concentrations in the TMJ region, whereas higher forces (400 g) generated increased stresses at the condylar head and articular disc. Conclusion: Within the limitations of a linear static model, moderate force levels and smaller angulations appear to offer a biomechanically favourable balance between skeletal advancement and TMJ loading during BAMP therapy. These findings represent immediate mechanical responses and should be interpreted cautiously. Future studies incorporating muscle forces, soft tissues, and time-dependent remodelling are warranted. © 2025 CEO

Copper-rich high entropy alloys (HEAs) offer a route to address the strength-ductility limits of conventional copper alloys through controlled phase and microstructural engineering. This work investigates the formation of dual-phase (two compositionally distinct face-centred cubic (FCC) phases) nanostructure in Cu50Mn30Co10Fe10 (Cu-HEA) upon friction stir processing (FSP). Shear-driven transport of elements during FSP caused the forced mixing of these Fe-rich (α2) and Cu-rich (α1) phases, resulting in the formation of a semi-coherent, structurally ordered diffused interface in the microstructure. Thus, stabilising nanosized phases and creating a gradient interface increased the yield strength (YS) to 850 ± 15 MPa after FSP, from an as-cast value of 450 MPa, while maintaining tensile ductility of 18 ± 3 %. The increase in YS is mainly attributed to the microstructural complexity arising from the formation of various microstructural features (such as nanograins, nanotwins, and phases) at different length scales during FSP. The increase in tensile ductility despite the rise in YS is mainly associated with pronounced back-stress strengthening in the early stage of deformation, followed by dynamic recovery at the α1/α2 and α1/α1 interfaces at later stages, which facilitates effective stress transfer. Thus, the FSP of Cu-HEA opened a new pathway to achieving balanced strength and ductility, which is otherwise difficult to attain in nanograined metallic microstructures. © 2026 Elsevier Ltd.

It is a fundamental question why quantum mechanics employs complex numbers rather than solely real numbers. In this work, we conduct the first analysis of imaginarity quantification in neutrino flavor and spin-flavor oscillations. As quantum systems in coherent superposition, neutrinos are ideal candidates for quantifying imaginarity within the resource theoretic framework, using measures such as the (Formula presented) (Formula presented) -norm and the relative entropy of imaginarity. We show that in the case of two-flavor mixing, these measures of imaginarity are nonzero. The measures of imaginarity reach their extreme values when the probabilistic features of quantum theory are fully maximized, i.e., both the transitional and survival probabilities are approximately equal. Our study reveals that the imaginarity, as a resource, can be harnessed not solely from the presence of a complex phase in the mixing matrix but also from the intrinsic quantum dynamics of time evolution itself. We further extend our analysis to explore the dynamics of three-flavor neutrino mixing, incorporating the effects of a nonzero (Formula presented) (Formula presented) phase. © 2026 IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved. This article is available under the terms of the https://publishingsupport.iopscience.iop.org/iop-standard/v1.

Neurodegenerative disorders such as Parkinson's (PD) and Alzheimer's diseases (AD) are linked with the assembly and accumulation of proteins into structured scaffold called amyloids. These diseases pose significant challenges due to their complex and multifaceted nature. While the primary focus has been on endogenous amyloids, recent evidence suggests that bacterial amyloids may contribute to the development and exacerbation of such disorders. The gut-brain axis is emerging as a communication pathway between bacterial and human amyloids. This review delves into the novel role and potential mechanism of bacterial amyloids in modulating human amyloid formation and the progression of AD and PD.

In the MaxSAT with Cardinality Constraint problem (CC-MaxSAT), we are given a CNF-formula Φ, and a positive integer k, and the goal is to find an assignment β with at most k variables set to true (also called a weight k-assignment) such that the number of clauses satisfied by β is maximized. Maximum Coverage can be seen as a special case of CC-MaxSat, where the formula Φ is monotone, i.e., does not contain any negative literals. CC-MaxSat and Maximum Coverage are extremely well-studied problems in the approximation algorithms as well as the parameterized complexity literature. Our first conceptual contribution is that CC-MaxSat and Maximum Coverage are equivalent to each other in the context of FPT-Approximation parameterized by k (here, the approximation is in terms of the number of clauses satisfied/elements covered). In particular, we give a randomized reduction from CC-MaxSat to Maximum Coverage running in time O(1/ϵ)k · (m + n)O(1) that preserves the approximation guarantee up to a factor of (1 − ϵ). Furthermore, this reduction also works in the presence of “fairness” constraints on the satisfied clauses, as well as matroid constraints on the set of variables that are assigned true. Here, the “fairness” constraints are modeled by partitioning the clauses of the formula Φ into r different colors, and the goal is to find an assignment that satisfies at least tj clauses of each color 1 ≤ j ≤ r. Armed with this reduction, we focus on designing FPT-Approximation schemes (FPT-ASes) for Maximum Coverage and its generalizations. Our algorithms are based on a novel combination of a variety of ideas, including a carefully designed probability distribution that exploits sparse coverage functions. These algorithms substantially generalize the results in Jain et al. [SODA 2023] for CC-MaxSat and Maximum Coverage for Kd,d-free set systems (i.e., no d sets share d elements), as well as a recent FPT-AS for Matroid Constrained Maximum Coverage by Sellier [ESA 2023] for frequency-d set systems.

The technique of micro-exfoliation has gained prominence as a highly effective and adaptable method for exploiting two-dimensional (2D) materials, such as graphene Transition metal dichalcogenides (TMDCs), Borophene, Molybdenum disulfide (MoS2), among others. This paper presents an analysis of optical images and the micro exfoliation technique, focusing on the application to MoS2 and graphene. Additionally, the study investigates the exfoliated sheet of graphene, MoS2, and their hybrid on a (111) crystal plane of silicon wafer. The micro-exfoliation technique employed for MoS2 involves a mechanical process that gently disentangles the layers of MoS2 from the larger crystal structure, resulting in the formation of ultrathin two-dimensional nanosheets. This paper comprehensively analyses the exfoliation processes' mechanisms, emphasizing the intricate relationship between van der Waals forces, interlayer bonding, and external forces. The micro-mechanical exfoliation, a fundamental technique, entails the utilization of adhesive scotch tape to remove monolayers from a large MoS2 crystal delicately. The integration of MoS2 into various applications such as electronics, optoelectronics, sensors, and energy storage devices has been driven by its exceptional properties, including its distinctive electronic, optical, and mechanical characteristics. Furthermore, the ability to adjust the bandgap of MoS2 has created novel opportunities for potential applications in the field of semiconductors. This paper provides a succinct summary of recent studies, that have concentrated on the optical characterization of MoS2 monolayers. Optical and Raman spectroscopy was employed to characterize the 2D sheets of MoS2 and its hybrid materials.