34,859 results on '"Ojha, A."'
Search Results
2. Findings of the IWSLT 2024 Evaluation Campaign
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Ahmad, Ibrahim Said, Anastasopoulos, Antonios, Bojar, Ondřej, Borg, Claudia, Carpuat, Marine, Cattoni, Roldano, Cettolo, Mauro, Chen, William, Dong, Qianqian, Federico, Marcello, Haddow, Barry, Javorský, Dávid, Krubiński, Mateusz, Lam, Tsz Kin, Ma, Xutai, Mathur, Prashant, Matusov, Evgeny, Maurya, Chandresh, McCrae, John, Murray, Kenton, Nakamura, Satoshi, Negri, Matteo, Niehues, Jan, Niu, Xing, Ojha, Atul Kr., Ortega, John, Papi, Sara, Polák, Peter, Pospíšil, Adam, Pecina, Pavel, Salesky, Elizabeth, Sethiya, Nivedita, Sarkar, Balaram, Shi, Jiatong, Sikasote, Claytone, Sperber, Matthias, Stüker, Sebastian, Sudoh, Katsuhito, Thompson, Brian, Turchi, Marco, Waibel, Alex, Watanabe, Shinji, Wilken, Patrick, Zemánek, Petr, and Zevallos, Rodolfo
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Computer Science - Computation and Language - Abstract
This paper reports on the shared tasks organized by the 21st IWSLT Conference. The shared tasks address 7 scientific challenges in spoken language translation: simultaneous and offline translation, automatic subtitling and dubbing, speech-to-speech translation, dialect and low-resource speech translation, and Indic languages. The shared tasks attracted 18 teams whose submissions are documented in 26 system papers. The growing interest towards spoken language translation is also witnessed by the constantly increasing number of shared task organizers and contributors to the overview paper, almost evenly distributed across industry and academia., Comment: IWSLT 2024; 59 pages
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- 2024
3. Masking Gaussian Elimination at Arbitrary Order, with Application to Multivariate- and Code-Based PQC
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Norga, Quinten, Kundu, Suparna, Ojha, Uttam Kumar, Ganguly, Anindya, Karmakar, Angshuman, and Verbauwhede, Ingrid
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Computer Science - Cryptography and Security - Abstract
Digital signature schemes based on multivariate- and code-based hard problems are promising alternatives for lattice-based signature schemes due to their smaller signature size. Hence, several candidates in the ongoing additional standardization for quantum secure digital signature (DS) schemes by the NIST rely on such alternate hard problems. Gaussian Elimination (GE) is a critical component in the signing procedure of these schemes. In this paper, we provide a masking scheme for GE with back substitution to defend against first- and higher-order attacks. To the best of our knowledge, this work is the first to analyze and propose masking techniques for multivariate- or code-based DS algorithms. We propose a masked algorithm for transforming a system of linear equations into row-echelon form. This is realized by introducing techniques for efficiently making leading (pivot) elements one while avoiding costly conversions between Boolean and multiplicative masking at all orders. We also propose a technique for efficient masked back substitution, which eventually enables a secure unmasking of the public output. We evaluate the overhead of our countermeasure for several post-quantum candidates and their different security levels at first-, second-, and third-order, including UOV, MAYO, SNOVA, QR-UOV, and MQ-Sign. Notably, the operational cost of first-, second-, and third-order masked GE is 2.3x higher, and the randomness cost is 1.2x higher in MAYO compared to UOV for security levels III and V. We also show detailed performance results for masked GE implementations for all three security versions of UOV on the Arm Cortex-M4 and compare them with unmasked results. Our first-order implementations targeting UOV parameters have overheads of factor 6.5x, 5.9x, and 5.7x compared to the unprotected implementation for NIST security level I, III, and V., Comment: 30 pages, 9 figures, 3 tables
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- 2024
4. Morphogenesis of Spin Cycloids in a Non-collinear Antiferromagnet
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Ojha, Shashank Kumar, Pal, Pratap, Prokhorenko, Sergei, Husain, Sajid, Ramesh, Maya, Meisenheimer, Peter, Schlom, Darrell G., Stevenson, Paul, Caretta, Lucas, Nahas, Yousra, Martin, Lane W., Bellaiche, Laurent, Eom, Chang-Beom, and Ramesh, Ramamoorthy
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Condensed Matter - Materials Science ,Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed Matter - Strongly Correlated Electrons - Abstract
Pattern formation in spin systems with continuous-rotational symmetry (CRS) provides a powerful platform to study emergent complex magnetic phases and topological defects in condensed-matter physics. However, its understanding and correlation with unconventional magnetic order along with high-resolution nanoscale imaging is challenging. Here, we employ scanning NV magnetometry to unveil the morphogenesis of spin cycloids at both the local and global scales within a single ferroelectric domain of (111)-oriented BiFeO$_3$ (which is a non-collinear antiferromagnet), resulting in formation of a glassy labyrinthine pattern. We find that the domains of locally oriented cycloids are interconnected by an array of topological defects and exhibit isotropic energy landscape predicted by first-principles calculations. We propose that the CRS of spin-cycloid propagation directions within the (111) drives the formation of the labyrinthine pattern and the associated topological defects such as antiferromagnetic skyrmions. Unexpectedly, reversing the as-grown ferroelectric polarization from [$\bar{1}$$\bar{1}$$\bar{1}$] to [111] induces a magnetic phase transition, destroying the labyrinthine pattern and producing a deterministic non-volatile non cycloidal, uniformly magnetized state. These findings highlight that (111)-oriented BiFeO$_3$ is not only important for studying the fascinating subject of pattern formation but could also be utilized as an ideal platform for integrating novel topological defects in the field of antiferromagnetic spintronics., Comment: 20 pages, 15 figures
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- 2024
5. Symmetry controlled single spin cycloid switching in multiferroic BiFeO3
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Pal, Pratap, Schad, Jonathon L., Vibhakar, Anuradha M., Ojha, Shashank Kumar, Kim, Gi-Yeop, Shenoy, Saurav, Xue, Fei, Rzchowski, Mark S., Bombardi, A., Johnson, Roger D., Choi, Si-Young, Chen, Long-Qing, Ramesh, Ramamoorthy, Radaelli, Paolo G., and Eom, Chang-Beom
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Condensed Matter - Materials Science ,Condensed Matter - Strongly Correlated Electrons - Abstract
The single variant spin cycloid and associated antiferromagnetic order in multiferroic BiFeO3 can provide a direct and predictable magnetoelectric coupling to ferroelectric order for deterministic switching, and also a key to fundamental understanding of spin transport and magnon-based applications in the system. (111) oriented BiFeO3 supplies an easy magnetic plane for the spin cycloid, but despite previous efforts, achieving deterministic switching of the single spin cycloid over multiple cycles remains challenging due to the presence of multiple spin cycloid domains in the (111) plane. Here we show that anisotropic in-plane strain engineering can stabilize a single antiferromagnetic domain and provide robust, deterministic switching. We grow BiFeO3 on orthorhombic NdGaO3 (011)o [(111)pc] substrates, breaking the spin cycloid degeneracy and by imposing a uniaxial strain in the (111) plane. This stabilization is confirmed through direct imaging with scanning NV microscopy and non-resonant X-ray diffraction. Remarkably, we achieved deterministic and non-volatile 180{\deg} switching of ferroelectric and associated antiferromagnetic domains over 1,000 cycles, significantly outperforming existing approaches. Our findings underscore that anisotropic strain engineering opens up exciting possibilities for (111)pc monodomain BiFeO3 in potential magnetoelectric and emerging magnonic applications., Comment: 17 pages, 4 figures
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- 2024
6. Twins in Diversity: Understanding circumstellar disk evolution in the twin clusters of W5 complex
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Damian, Belinda, Jose, Jessy, Das, Swagat R., Gupta, Saumya, Vaikundaraman, Vignesh, Ojha, D. K., Kartha, Sreeja S., Panwar, Neelam, and Eswaraiah, Chakali
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Astrophysics - Solar and Stellar Astrophysics ,Astrophysics - Astrophysics of Galaxies - Abstract
Young star-forming regions in massive environments are ideal test beds to study the influence of surroundings on the evolution of disks around low-mass stars. We explore two distant young clusters, IC 1848-East and West located in the massive W5 complex. These clusters are unique due to their similar (distance, age, and extinction) yet distinct (stellar density and FUV radiation fields) physical properties. We use deep multi-band photometry in optical, near-IR, and mid-IR wavelengths complete down to the substellar limit in at least five bands. We trace the spectral energy distribution of the sources to identify the young pre-main sequence members in the region and derive their physical parameters. The disk fraction for the East and West clusters down to 0.1 M$_\odot$ was found to be $\sim$27$\pm$2% (N$_{disk}$=184, N$_{diskless}$=492) and $\sim$17$\pm$1% (N$_{disk}$=173, N$_{diskless}$=814), respectively. While no spatial variation in the disk fraction is observed, these values are lower than those in other nearby young clusters. Investigating the cause of this decrease, we find a correlation with the intense feedback from massive stars throughout the cluster area. We also identified the disk sources undergoing accretion and observed the mass accretion rates to exhibit a positive linear relationship with the stellar host mass and an inverse relationship with stellar age. Our findings suggest that the environment significantly influences the dissipation of disks in both clusters. These distant clusters, characterized by their unique attributes, can serve as templates for future studies in outer galaxy regions, offering insights into the influence of feedback mechanisms on star and planetary formation., Comment: Accepted for publication in Monthly Notices of the Royal Astronomical Society (MNRAS). 18 pages, 11 figures, 1 table
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- 2024
7. Phase space distributions in information theory
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Ojha, Vikash Kumar, Radhakrishnan, Ramkumar, Tiwari, Siddharth Kumar, and Ughradar, Mariyah
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Quantum Physics - Abstract
We use phase space distributions specifically, the Wigner distribution (WD) and Husimi distribution (HD) to investigate certain information-theoretic measures as descriptors for a given system. We extensively investigate and analyze Shannon, Wehrl and Renyi entropies, its divergences, mutual information and other correlation measures within the context of these phase space distributions. The analysis is illustrated with an anharmonic oscillator and is studied with respect to perturbation parameter ($\lambda$) and states ($n$). The entropies associated with the Wigner distribution are observed to be lower than those of the Husimi distribution, which aligns with the findings regarding the marginals. Moreover, the real components of the entropies associated with the Wigner distribution tend to approach the entropic uncertainty bound more closely compared to those of the corresponding Husimi distribution. Moreover, we quantify the precise amount of information lost when opting for the Husimi distribution over the Wigner distribution for characterizing the specified system. Since it is not always positive definite, the entropies cannot always be defined.
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- 2024
8. On the Effectiveness of Dataset Alignment for Fake Image Detection
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Rajan, Anirudh Sundara, Ojha, Utkarsh, Schloesser, Jedidiah, and Lee, Yong Jae
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Computer Science - Computer Vision and Pattern Recognition - Abstract
As latent diffusion models (LDMs) democratize image generation capabilities, there is a growing need to detect fake images. A good detector should focus on the generative models fingerprints while ignoring image properties such as semantic content, resolution, file format, etc. Fake image detectors are usually built in a data driven way, where a model is trained to separate real from fake images. Existing works primarily investigate network architecture choices and training recipes. In this work, we argue that in addition to these algorithmic choices, we also require a well aligned dataset of real/fake images to train a robust detector. For the family of LDMs, we propose a very simple way to achieve this: we reconstruct all the real images using the LDMs autoencoder, without any denoising operation. We then train a model to separate these real images from their reconstructions. The fakes created this way are extremely similar to the real ones in almost every aspect (e.g., size, aspect ratio, semantic content), which forces the model to look for the LDM decoders artifacts. We empirically show that this way of creating aligned real/fake datasets, which also sidesteps the computationally expensive denoising process, helps in building a detector that focuses less on spurious correlations, something that a very popular existing method is susceptible to. Finally, to demonstrate just how effective the alignment in a dataset can be, we build a detector using images that are not natural objects, and present promising results. Overall, our work identifies the subtle but significant issues that arise when training a fake image detector and proposes a simple and inexpensive solution to address these problems.
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- 2024
9. Long-term evolution of spin and other properties of neutron star low-mass X-ray binaries: implications for millisecond X-ray pulsars
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Kar, Abhijnan, Ojha, Pulkit, and Bhattacharyya, Sudip
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Astrophysics - High Energy Astrophysical Phenomena - Abstract
A neutron star (NS) accreting matter from a companion star in a low-mass X-ray binary (LMXB) system can spin up to become a millisecond pulsar (MSP). Properties of many such MSP systems are known, which is excellent for probing fundamental aspects of NS physics when modelled using the theoretical computation of NS LMXB evolution. Here, we systematically compute the long-term evolution of NS, binary and companion parameters for NS LMXBs using the stellar evolution code MESA. We consider the baryonic to gravitational mass conversion to calculate the NS mass evolution and show its cruciality for the realistic computation of some parameters. With computations using many combinations of parameter values, we find the general nature of the complex NS spin frequency ($\nu$) evolution, which depends on various parameters, including accretion rate, fractional mass loss from the system, and companion star magnetic braking. Further, we utilize our results to precisely match some main observed parameters, such as $\nu$, orbital period ($P_{\rm orb}$), etc., of four accreting millisecond X-ray pulsars (AMXPs). By providing the $\nu$, $P_{\rm orb}$ and the companion mass spaces for NS LMXB evolution, we indicate the distribution and plausible evolution of a few other AMXPs. We also discuss the current challenges in explaining the parameters of AMXP sources with brown dwarf companions and indicate the importance of modelling the transient accretion in LMXBs as a possible solution., Comment: 20 pages, 16 figures, 1 table, accepted for publication in Monthly Notices of the Royal Astronomical Society. The first two authors are co-first authors
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- 2024
10. Strategic Collusion of LLM Agents: Market Division in Multi-Commodity Competitions
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Lin, Ryan Y., Ojha, Siddhartha, Cai, Kevin, and Chen, Maxwell F.
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Computer Science - Computer Science and Game Theory ,Computer Science - Artificial Intelligence ,Computer Science - Computation and Language ,Quantitative Finance - Computational Finance - Abstract
Machine-learning technologies are seeing increased deployment in real-world market scenarios. In this work, we explore the strategic behaviors of large language models (LLMs) when deployed as autonomous agents in multi-commodity markets, specifically within Cournot competition frameworks. We examine whether LLMs can independently engage in anti-competitive practices such as collusion or, more specifically, market division. Our findings demonstrate that LLMs can effectively monopolize specific commodities by dynamically adjusting their pricing and resource allocation strategies, thereby maximizing profitability without direct human input or explicit collusion commands. These results pose unique challenges and opportunities for businesses looking to integrate AI into strategic roles and for regulatory bodies tasked with maintaining fair and competitive markets. The study provides a foundation for further exploration into the ramifications of deferring high-stakes decisions to LLM-based agents.
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- 2024
11. Searching for GEMS: TOI-5688 A b, a low-density giant orbiting a high-metallicity early M-dwarf
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Reji, Varghese, Kanodia, Shubham, Ninan, Joe, Cañas, Caleb I., Libby-Roberts, Jessica, Lin, Andrea S. J., Gupta, Arvind F, Sewaby, Tera N., Larsen, Alexander, Kobulnicky, Henry A., Choi, Philip I., Evans, Nez, Santomenna, Sage, Winnick, Isabelle, Yu, Larry, Alvarado-Montes, Jaime A., Bender, Chad, Bernabò, Lia Marta, Blake, Cullen H., Cochran, William D., Diddams, Scott A., Halverson, Samuel, Han, Te, Hearty, Fred, Logsdon, Sarah E., Mahadevan, Suvrath, Monson, Andrew, McElwain, Michael, Robertson, Paul, Ojha, Devendra, Roy, Arpita, Schwab, Christian, Stefansson, Gudmundur, and Wright, Jason
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Astrophysics - Earth and Planetary Astrophysics - Abstract
We present the discovery of a low-density planet transiting TOI-5688 A b, a high-metallicity M2V star. This planet was discovered as part of the search for transiting giant planets ($R \gtrsim8$ M$_\oplus$) through the Searching for GEMS (Giant Exoplanets around M-dwarf Stars) survey. The planet TOI-5688 A b was discovered with the Transiting Exoplanet Survey Satellite (TESS), and characterized with ground-based transits from Red Buttes Observatory (RBO), the Table Mountain Observatory of Pomona College, and radial velocity (RV) measurements with the Habitable-Zone Planet Finder (HPF) on the 10 m Hobby Eberly Telescope (HET) and NEID on the WIYN 3.5 m telescope. From the joint fit of transit and RV data, the mass of the planet is $124\pm24$ M$_\oplus$ and the radius is $10.4\pm0.7$ R$_\oplus$. This planet has a density of $0.61^{+0.20}_{-0.15}$ g/cm${}^3$, and is on a $\sim2.95$ day orbit around its host star. The spectroscopic and photometric analysis of the host star TOI-5688 A shows that it is a high metallicity ([Fe/H] $ = 0.47\pm0.16$ dex) M2V star, favoring the core-accretion formation pathway as the likely formation scenario for this planet. In this paper, we analyze potential mechanisms of planet formation in the context of the formation of TOI-5688 A b. Additionally, observations with Gaia suggest the presence of a wide-separation binary companion, TOI-5688 B, which has a projected separation of $\sim5"$ (1110 AU) and is an M4V. This makes TOI-5688 A b part of a growing number of GEMS in wide-separation binary systems., Comment: 20 pages, 7 figures, Submitted to AJ, Comments are welcome
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- 2024
12. Prediction of Threonine-Tyrosine Kinase Receptor-Ligand Unbinding Kinetics with Multiscale Milestoning and Metadynamics.
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Votapka, Lane, Ojha, Anupam, Asada, Naoya, and Amaro, Rommie
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Ligands ,Kinetics ,Molecular Dynamics Simulation ,Thermodynamics ,Protein Kinase Inhibitors ,Protein Binding ,Protein Serine-Threonine Kinases - Abstract
Accurately describing protein-ligand binding and unbinding kinetics remains challenging. Computational calculations are difficult and costly, while experimental measurements often lack molecular detail and can be unobtainable. Here, we extend our multiscale milestoning method, Simulation-Enabled Estimation of Kinetics Rates (SEEKR), with metadynamics molecular dynamics simulations to yield accurate small molecule drug residence times. Using the pharmaceutically relevant threonine-tyrosine kinase (TTK) and eight long-residence-time (tens of seconds to hours) inhibitors, we demonstrate accurate prediction of absolute and rank-ordered ligand residence times and free energies of binding.
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- 2024
13. Dynamic Label Adversarial Training for Deep Learning Robustness Against Adversarial Attacks
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Liu, Zhenyu, Duan, Haoran, Liang, Huizhi, Long, Yang, Snasel, Vaclav, Nicosia, Guiseppe, Ranjan, Rajiv, and Ojha, Varun
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Computer Science - Machine Learning ,Computer Science - Computer Vision and Pattern Recognition - Abstract
Adversarial training is one of the most effective methods for enhancing model robustness. Recent approaches incorporate adversarial distillation in adversarial training architectures. However, we notice two scenarios of defense methods that limit their performance: (1) Previous methods primarily use static ground truth for adversarial training, but this often causes robust overfitting; (2) The loss functions are either Mean Squared Error or KL-divergence leading to a sub-optimal performance on clean accuracy. To solve those problems, we propose a dynamic label adversarial training (DYNAT) algorithm that enables the target model to gradually and dynamically gain robustness from the guide model's decisions. Additionally, we found that a budgeted dimension of inner optimization for the target model may contribute to the trade-off between clean accuracy and robust accuracy. Therefore, we propose a novel inner optimization method to be incorporated into the adversarial training. This will enable the target model to adaptively search for adversarial examples based on dynamic labels from the guiding model, contributing to the robustness of the target model. Extensive experiments validate the superior performance of our approach.
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- 2024
14. Peering into the Heart of the Giant Molecular Cloud G148.24+00.41: A Deep Near-infrared View of the Newly Hatched Cluster FSR 655
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Rawat, Vineet, Samal, M. R., Ojha, D. K., Kumar, Brajesh, Sharma, Saurabh, Jose, J., Sagar, Ram, and Yadav, R. K.
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Astrophysics - Astrophysics of Galaxies ,Astrophysics - Solar and Stellar Astrophysics - Abstract
We present a detailed near-infrared study of an embedded cluster located in the hub of the giant molecular cloud G148.24+00.41 of mass $\sim$10$^5$ $M_\odot$, with the TANSPEC instrument mounted on the 3.6 m Devasthal Optical Telescope. The hub is located near the geometric center of the cloud and represents its most massive clump. We studied the central 2 pc $\times$ 2 pc area of the hub with 5$\sigma$ limiting magnitudes of 20.5, 20.1, and 18.6 mag in the $J$, $H$, and $K_s$ bands, respectively. Using the $K_s$-band luminosity function and comparing it with the synthetic clusters, we obtained the age of the cluster as $\sim$0.5 Myr, which was found to corroborate well with the visual extinction versus the age of nearby embedded clusters. We find that the present mass of the cluster is around $\sim$180 $M_\odot$, and the cluster is currently forming stars at a rate of $\sim$330 $M_\odot$ $\rm{Myr}^{-1}$, with an efficiency of $\sim$20%. The cluster is connected to an extended gas reservoir through a filamentary network; thus, we hypothesize that the cluster has the potential to become a richer cluster in a few Myr of time., Comment: 17 pages and 13 figures
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- 2024
15. On Learnable Parameters of Optimal and Suboptimal Deep Learning Models
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Zheng, Ziwei, Liang, Huizhi, Snasel, Vaclav, Latora, Vito, Pardalos, Panos, Nicosia, Giuseppe, and Ojha, Varun
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Computer Science - Machine Learning ,Computer Science - Computer Vision and Pattern Recognition - Abstract
We scrutinize the structural and operational aspects of deep learning models, particularly focusing on the nuances of learnable parameters (weight) statistics, distribution, node interaction, and visualization. By establishing correlations between variance in weight patterns and overall network performance, we investigate the varying (optimal and suboptimal) performances of various deep-learning models. Our empirical analysis extends across widely recognized datasets such as MNIST, Fashion-MNIST, and CIFAR-10, and various deep learning models such as deep neural networks (DNNs), convolutional neural networks (CNNs), and vision transformer (ViT), enabling us to pinpoint characteristics of learnable parameters that correlate with successful networks. Through extensive experiments on the diverse architectures of deep learning models, we shed light on the critical factors that influence the functionality and efficiency of DNNs. Our findings reveal that successful networks, irrespective of datasets or models, are invariably similar to other successful networks in their converged weights statistics and distribution, while poor-performing networks vary in their weights. In addition, our research shows that the learnable parameters of widely varied deep learning models such as DNN, CNN, and ViT exhibit similar learning characteristics.
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- 2024
16. Security Assessment of Hierarchical Federated Deep Learning
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Alqattan, D, Sun, R, Liang, H, Nicosia, G, Snasel, V, Ranjan, R, and Ojha, V
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Computer Science - Machine Learning ,Computer Science - Artificial Intelligence ,Computer Science - Cryptography and Security - Abstract
Hierarchical federated learning (HFL) is a promising distributed deep learning model training paradigm, but it has crucial security concerns arising from adversarial attacks. This research investigates and assesses the security of HFL using a novel methodology by focusing on its resilience against adversarial attacks inference-time and training-time. Through a series of extensive experiments across diverse datasets and attack scenarios, we uncover that HFL demonstrates robustness against untargeted training-time attacks due to its hierarchical structure. However, targeted attacks, particularly backdoor attacks, exploit this architecture, especially when malicious clients are positioned in the overlapping coverage areas of edge servers. Consequently, HFL shows a dual nature in its resilience, showcasing its capability to recover from attacks thanks to its hierarchical aggregation that strengthens its suitability for adversarial training, thereby reinforcing its resistance against inference-time attacks. These insights underscore the necessity for balanced security strategies in HFL systems, leveraging their inherent strengths while effectively mitigating vulnerabilities.
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- 2024
17. RollingCache: Using Runtime Behavior to Defend Against Cache Side Channel Attacks
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Ojha, Divya and Dwarkadas, Sandhya
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Computer Science - Cryptography and Security ,Computer Science - Hardware Architecture - Abstract
Shared caches are vulnerable to side channel attacks through contention in cache sets. Besides being a simple source of information leak, these side channels form useful gadgets for more sophisticated attacks that compromise the security of shared systems. The fundamental design aspect that contention attacks exploit is the deterministic nature of the set of addresses contending for a cache set. In this paper, we present RollingCache, a cache design that defends against contention attacks by dynamically changing the set of addresses contending for cache sets. Unlike prior defenses, RollingCache does not rely on address encryption/decryption, data relocation, or cache partitioning. We use one level of indirection to implement dynamic mapping controlled by the whole-cache runtime behavior. Our solution does not depend on having defined security domains, and can defend against an attacker running on the same or another core. We evaluate RollingCache on ChampSim using the SPEC-2017 benchmark suite. Our security evaluation shows that our dynamic mapping removes the deterministic ability to identify the source of contention. The performance evaluation shows an impact of 1.67\% over a mix of workloads, with a corresponding
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- 2024
18. Structure-preserving Planar Simplification for Indoor Environments
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Khanal, Bishwash, Rijal, Sanjay, Awale, Manish, and Ojha, Vaghawan
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Computer Science - Computer Vision and Pattern Recognition ,Computer Science - Computational Geometry - Abstract
This paper presents a novel approach for structure-preserving planar simplification of indoor scene point clouds for both simulated and real-world environments. Initially, the scene point cloud undergoes preprocessing steps, including noise reduction and Manhattan world alignment, to ensure robustness and coherence in subsequent analyses. We segment each captured scene into structured (walls-ceiling-floor) and non-structured (indoor objects) scenes. Leveraging a RANSAC algorithm, we extract primitive planes from the input point cloud, facilitating the segmentation and simplification of the structured scene. The best-fitting wall meshes are then generated from the primitives, followed by adjacent mesh merging with the vertex-translation algorithm which preserves the mesh layout. To accurately represent ceilings and floors, we employ the mesh clipping algorithm which clips the ceiling and floor meshes with respect to wall normals. In the case of indoor scenes, we apply a surface reconstruction technique to enhance the fidelity. This paper focuses on the intricate steps of the proposed scene simplification methodology, addressing complex scenarios such as multi-story and slanted walls and ceilings. We also conduct qualitative and quantitative performance comparisons against popular surface reconstruction, shape approximation, and floorplan generation approaches.
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- 2024
19. Force-Motion Control For A Six Degree-Of-Freedom Robotic Manipulator
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Ojha, Sagar, Leodler, Karl, Barbieri, Lou, and Wu, TseHuai
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Computer Science - Robotics ,Mathematics - Dynamical Systems - Abstract
This paper presents a unified algorithm for motion and force control for a six degree-of-freedom spatial manipulator. The motion-force controller performs trajectory tracking, maneuvering the manipulator's end-effector through desired position, orientations and rates. When contacting an obstacle or target object, the force module of the controller restricts the manipulator movements with a novel force exertion method, which prevents damage to the manipulator, the end-effector, and the objects during the contact or collision. The core strategy presented in this paper is to design the linear acceleration for the end-effector which ensures both trajectory tracking and restriction of any contact force at the end-effector. The design of the controller is validated through numerical simulations and digital twin validation.
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- 2024
20. Study of the high-mass star-forming region S255IR at various scales
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Zinchenko, I. I., Liu, S. -Y., Ojha, D. K., Su, Y. -N., and Zemlyanukha, P. M.
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Astrophysics - Astrophysics of Galaxies - Abstract
The S255IR-SMA1 core contains the protostar NIRS3 with a mass of $\sim$20 M$_\odot$. Several years ago, the first burst of luminosity for massive protostars, caused by an episodic accretion event, was recorded here. We have been studying this object for a long time using various instruments, including ALMA. The general morphology and kinematics of this area have been investigated. Disk-shaped structures, jets and outflows have been identified and studied in detail. We recently observed this object with ALMA with a resolution an order of magnitude higher than previously achieved - about 15 milliarcseconds, which corresponds to about 25 AU. This paper presents new results from the analysis of these data together with observations in other bands. The new data show an inhomogeneous disk structure, an ionized region around the protostar, and the presence of a jet observed in the submillimeter continuum, consisting of individual knots, the orientation of which differs markedly from that on large scales. The submillimeter emission from the jet most likely represents bremsstrahlung from ionized gas. Based on observations of the lines of some molecules, the kinematics and physical characteristics of this region are discussed. Methanol maser emission associated with the jet is observed., Comment: 6 pages, 3 figures, accepted to Proceedings of the conference "Modern astronomy: from the early Universe to exoplanets and black holes" (August 25-31, Nizhny Arkhyz, Russia)
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- 2024
21. Artificial Intelligence Based Navigation in Quasi Structured Environment
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Kumar, Hariram Sampath, Singh, Archana, and Ojha, Manish Kumar
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Computer Science - Neural and Evolutionary Computing ,Computer Science - Artificial Intelligence - Abstract
The proper planning of different types of public transportation such as metro, highway, waterways, and so on, can increase the efficiency, reduce the congestion and improve the safety of the country. There are certain challenges associated with route planning, such as high cost of implementation, need for adequate resource & infrastructure and resistance to change. The goal of this research is to examine the working, applications, complexity factors, advantages & disadvantages of Floyd- Warshall, Bellman-Ford, Johnson, Ant Colony Optimization (ACO), Particle Swarm Optimization (PSO), & Grey Wolf Optimizer (GWO), to find the best choice for the above application. In this paper, comparative analysis of above-mentioned algorithms is presented. The Floyd-Warshall method and ACO algorithm are chosen based on the comparisons. Also, a combination of modified Floyd-Warshall with ACO algorithm is proposed. The proposed algorithm showed better results with less time complexity, when applied on randomly structured points within a boundary called quasi-structured points. In addition, this paper also discusses the future works of integrating Floyd-Warshall with ACO to develop a real-time model for overcoming above mentioned-challenges during transportation route planning., Comment: 10 pages, 8 figures
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- 2024
22. Advanced Artificial Intelligence Strategy for Optimizing Urban Rail Network Design using Nature-Inspired Algorithms
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Kumar, Hariram Sampath, Singh, Archana, and Ojha, Manish Kumar
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Computer Science - Neural and Evolutionary Computing ,Computer Science - Artificial Intelligence - Abstract
This study introduces an innovative methodology for the planning of metro network routes within the urban environment of Chennai, Tamil Nadu, India. A comparative analysis of the modified Ant Colony Optimization (ACO) method (previously developed) with recent breakthroughs in nature-inspired algorithms demonstrates the modified ACO's superiority over modern techniques. By utilizing the modified ACO algorithm, the most efficient routes connecting the origin and destination of the metro route are generated. Additionally, the model is applied to the existing metro network to highlight variations between the model's results and the current network. The Google Maps platform, integrated with Python, handles real-time data, including land utilization, Geographical Information Systems (GIS) data, census information, and points of interest. This processing enables the identification of stops within the city and along the chosen routes. The resulting metro network showcases substantial benefits compared to conventional route planning methods, with noteworthy enhancements in workforce productivity, decreased planning time, and cost-efficiency. This study significantly enhances the efficiency of urban transport systems, specifically in rapidly changing metropolitan settings such as chennai., Comment: 10 pages, 17 figures
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- 2024
23. Investigating the Star-forming Sites in the Outer Galactic Arm
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Verma, Aayushi, Sharma, Saurabh, Dewangan, Lokesh K., Ojha, Devendra K., Mallick, Kshitiz, Yadav, Ram Kesh, Kaur, Harmeen, Chand, Tarak, Agarwal, Mamta, and Gupta, Archana
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Astrophysics - Astrophysics of Galaxies - Abstract
We aim to investigate the global star formation scenario in star-forming sites AFGL 5157, [FSR2007] 0807 (hereafter FSR0807), [HKS2019] E70 (hereafter E70), [KPS2012] MWSC 0620 (hereafter KPS0620), and IRAS 05331+3115 in the outer galactic arm. The distribution of young stellar objects in these sites coincides with a higher extinction and H2 column density, which agrees with the notion that star formation occurs inside the dense molecular cloud cores. We have found two molecular structures at different velocities in this direction; one contains AFGL 5157 and FSR0807, and the other contains E70, [KPS2012] MWSC 0620, and IRAS 05331+3115. All these clusters in our target region are in different evolutionary stages and might form stars through different mechanisms. The E70 cluster seems to be the oldest in our sample; AFGL 5157 and FSR0807 formed later, and KPS0620 and IRAS 05331+3115 are the youngest sites. AFGL 5157 and FSR0807 are physically connected and have cold filamentary structures and dense hub regions. Additionally, the near-infrared photometric analysis shows signatures of massive star formation in these sites. KPS0620 also seems to have cold filamentary structures with the central hub but lacks signatures of massive stars. Our analysis suggests molecular gas flow and the hub filamentary star formation scenario in these regions. IRAS 05331+3115 is a single clump of molecular gas favoring low-mass star formation. Our study suggests that the selected area is a menagerie of star-forming sites where the formation of the stars happens through different processes., Comment: 19 pages, 13 figures, and 3 tables; Accepted for publication in AJ
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- 2024
24. Yo'LLaVA: Your Personalized Language and Vision Assistant
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Nguyen, Thao, Liu, Haotian, Li, Yuheng, Cai, Mu, Ojha, Utkarsh, and Lee, Yong Jae
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Computer Science - Computer Vision and Pattern Recognition ,Computer Science - Machine Learning - Abstract
Large Multimodal Models (LMMs) have shown remarkable capabilities across a variety of tasks (e.g., image captioning, visual question answering). While broad, their knowledge remains generic (e.g., recognizing a dog), and they are unable to handle personalized subjects (e.g., recognizing a user's pet dog). Human reasoning, in contrast, typically operates within the context of specific subjects in our surroundings. For example, one might ask, "What should I buy for my dog's birthday?"; as opposed to a generic inquiry about "What should I buy for a dog's birthday?". Similarly, when looking at a friend's image, the interest lies in seeing their activities (e.g., "my friend is holding a cat"), rather than merely observing generic human actions (e.g., "a man is holding a cat"). In this paper, we introduce the novel task of personalizing LMMs, so that they can have conversations about a specific subject. We propose Yo'LLaVA, which learns to embed a personalized subject into a set of latent tokens given a handful of example images of the subject. Our qualitative and quantitative analyses reveal that Yo'LLaVA can learn the concept more efficiently using fewer tokens and more effectively encode the visual attributes compared to strong prompting baselines (e.g., LLaVA)., Comment: Project page: https://thaoshibe.github.io/YoLLaVA
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- 2024
25. Low-mass stellar and substellar content of the young cluster Berkeley 59
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Panwar, Neelam, C., Rishi, Sharma, Saurabh, Ojha, Devendra K., Samal, Manash R., Singh, H. P., and Yadav, Ram Kesh
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Astrophysics - Astrophysics of Galaxies ,Astrophysics - Solar and Stellar Astrophysics - Abstract
We present a multi-wavelength analysis of the young star cluster Berkeley 59 (Be 59) based on the $Gaia$ data and deep infrared (IR) observations with the 3.58-m Telescopio Nazionale Galileo and $Spitzer$ space telescope. The mean proper motion of the cluster is found to be $\mu$$_\alpha$cos$\delta$ $\sim$ -0.63 mas yr$^{-1}$ and $\mu$$_\delta$ $\sim$ -1.83 mas yr$^{-1}$ and the kinematic distance of the cluster, $\sim$ 1 kpc, is in agreement with previous photometric studies. Present data is the deepest available near-IR observations for the cluster so far and reached below 0.03 M$_\odot$. The mass function of the cluster region is calculated using the statistically cleaned color-magnitude diagram and is similar to the Salpeter value for the member stars above 0.4 M$_\odot$. In contrast, the slope becomes shallower ($\Gamma$ $\sim$ 0.01 $\pm$ 0.18) in the mass range 0.04 - 0.4 M$_\odot$, comparable to other nearby clusters. The spatial distribution of young brown dwarfs (BDs) and stellar candidates shows a non-homogeneous distribution. This suggests that the radiation feedback from massive stars may be a prominent factor contributing to the BD population in the cluster Be 59. We also estimated the star-to-BD ratio for the cluster, which is found to be $\sim$ 3.6. The Kolomogorov-Smirnov test shows that stellar and BD populations significantly differ, and stellar candidates are near the cluster center compared to the BDs, suggesting mass segregation in the cluster toward the substellar mass regime., Comment: 18 pages, 11 Figures, accepted for the publication in the AJ
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- 2024
26. Are Large Language Models Actually Good at Text Style Transfer?
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Mukherjee, Sourabrata, Ojha, Atul Kr., and Dušek, Ondřej
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Computer Science - Computation and Language - Abstract
We analyze the performance of large language models (LLMs) on Text Style Transfer (TST), specifically focusing on sentiment transfer and text detoxification across three languages: English, Hindi, and Bengali. Text Style Transfer involves modifying the linguistic style of a text while preserving its core content. We evaluate the capabilities of pre-trained LLMs using zero-shot and few-shot prompting as well as parameter-efficient finetuning on publicly available datasets. Our evaluation using automatic metrics, GPT-4 and human evaluations reveals that while some prompted LLMs perform well in English, their performance in on other languages (Hindi, Bengali) remains average. However, finetuning significantly improves results compared to zero-shot and few-shot prompting, making them comparable to previous state-of-the-art. This underscores the necessity of dedicated datasets and specialized models for effective TST.
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- 2024
27. First VLBI detection of Fornax A
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Paraschos, G. F., Wielgus, M., Benke, P., Mpisketzis, V., Rösch, F., Dasyra, K., Ros, E., Kadler, M., Ojha, R., Edwards, P. G., Hyland, L., Quick, J. F. H., and Weston, S.
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Astrophysics - Astrophysics of Galaxies ,Astrophysics - High Energy Astrophysical Phenomena - Abstract
Radio galaxies harbouring jetted active galactic nuclei are a frequent target of very-long-baseline interferometry (VLBI) because they play an essential role in exploring how jets form and propagate. Hence, only few have not been detected with VLBI yet; Fornax A is one of the most famous examples. Here we present the first detection of the compact core region of Fornax A with VLBI. At 8.4 GHz the faint core is consistent with an unresolved point source. We constrained its flux density to be $S_0 = 47.5-62.3\,\textrm{mJy}$ and its diameter to be $D^\textrm{min}_0 \leq 70\,\mu\textrm{as}$. The high values of the measured brightness temperature ($T_\textrm{B} \gtrsim 10^{11}\,\textrm{K}$) imply that the observed radiation is of non-thermal origin, likely associated with the synchrotron emission from the active galactic nucleus. We also investigated the possibility of a second radio source being present within the field of view. Adding a second Gaussian component to the geometrical model-fit does not significantly improve the quality of the fit and we, therefore, conclude that our detection corresponds to the compact core of Fornax A. Analysis of the non-trivial closure phases provides evidence for the detection of more extended flux density, on the angular scale of $\sim4000\,\mu\textrm{as}$. Finally, the fractional circular polarisation of the core is consistent with zero, with a conservative upper limit being $m_\textrm{circ} \leq 4\%$., Comment: 4 pages, 2 figures, accepted for publication in A&A
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- 2024
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28. Simulation-driven design of stabilized SARS-CoV-2 spike S2 immunogens.
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Nuqui, Xandra, Casalino, Lorenzo, Zhou, Ling, Shehata, Mohamed, Wang, Albert, Tse, Alexandra, Ojha, Anupam, Kearns, Fiona, Rosenfeld, Mia, Miller, Emily, Acreman, Cory, Ahn, Shirley, Chandran, Kartik, McLellan, Jason, and Amaro, Rommie
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Spike Glycoprotein ,Coronavirus ,SARS-CoV-2 ,Humans ,COVID-19 Vaccines ,Molecular Dynamics Simulation ,COVID-19 ,Cryoelectron Microscopy ,Protein Stability ,Antibodies ,Neutralizing ,Antibodies ,Viral ,Animals - Abstract
The full-length prefusion-stabilized SARS-CoV-2 spike (S) is the principal antigen of COVID-19 vaccines. Vaccine efficacy has been impacted by emerging variants of concern that accumulate most of the sequence modifications in the immunodominant S1 subunit. S2, in contrast, is the most evolutionarily conserved region of the spike and can elicit broadly neutralizing and protective antibodies. Yet, S2s usage as an alternative vaccine strategy is hampered by its general instability. Here, we use a simulation-driven approach to design S2-only immunogens stabilized in a closed prefusion conformation. Molecular simulations provide a mechanistic characterization of the S2 trimers opening, informing the design of tryptophan substitutions that impart kinetic and thermodynamic stabilization. Structural characterization via cryo-EM shows the molecular basis of S2 stabilization in the closed prefusion conformation. Informed by molecular simulations and corroborated by experiments, we report an engineered S2 immunogen that exhibits increased protein expression, superior thermostability, and preserved immunogenicity against sarbecoviruses.
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- 2024
29. Antibiotic Resistance Pattern of Bacteria Isolated from Clinical Specimens: A Hospital-Based Cross-sectional Study in Kathmandu, Nepal
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Parajuli, Rajendra Prasad Parajuli, Bharati, Niten, Bhandari, Shristi, Patel, Dharmaraj Kumar, Neupane, Arti, Ansari, Zainuddin, Ojha, Raj, Karmacharya, Anju, Anisha, KC, Bhusal, Rachana, Chettri, Yamini, Lama, Merina, Magar, Tsunami Thapa, Shilpakar, Minu, Gautam, Sandhya, Nepal, Madan, Yadav, Navin Kumar, Bhattarai, Muna, Bhattarai, Bimala, Bhusal, Shaniya, Chaudhary, Ganesh, Gautam, Jitendra, and Dumre, Shyam Prakash
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Biological Sciences ,Biomedical and Clinical Sciences ,Microbiology ,Clinical Sciences ,Medical Microbiology ,Emerging Infectious Diseases ,Infectious Diseases ,Clinical Research ,Biodefense ,Antimicrobial Resistance ,2.2 Factors relating to the physical environment ,5.1 Pharmaceuticals ,Infection ,Good Health and Well Being - Abstract
Antibiotics are vital in combating infectious diseases, yet their increasing use fosters resistance. Antimicrobial resistance (AMR) is rising in Nepal due to factors such as indiscriminate, inappropriate, and inadequate antibiotic usage. This study aims to explore the association between demographic factors and the prevalence of specific bacterial strains within the surveyed population. Additionally, it seeks to determine the antibiotic resistance patterns of these bacteria. Antibiotic susceptibility or resistance data were retrieved from the Medical Records Department (MRD) of the Manmohan Memorial Medical College and Teaching Hospital (MMMCTH) in Kathmandu. Samples from patients with certain types of bacterial infections were included, with 56 from sputum reports, 46 from urine, and 8 from blood samples out of 110 retrieved. Analysis revealed that sputum samples were mostly from older males, while urine samples were mostly from females. Yet, gender did not significantly influence bacterial presence across sample types. Overall, Escherichia coli was the most prevalent bacterium (74%), followed by Salmonella typhi (25%), Staphylococcus aureus (25%), and Klebsiella pneumoniae (23%) isolated from different type of clinical samples. Altogether, 6-15 antibiotics were assessed for sensitivity, with 2–6 antibiotics showing sensitivity to blood bacteria, 1-6 antibiotics demonstrating sensitivity to sputum bacteria, and 3–8 antibiotics exhibiting sensitivity to urine bacteria. Many investigated antibiotics were resistant, only gentamicin exhibited sensitivity for all types of bacteria found in blood, sputum and urine. These findings underscore the importance of discerning bacterial resistance patterns for effective antimicrobial treatment selection.
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- 2024
30. Multilingual Text Style Transfer: Datasets & Models for Indian Languages
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Mukherjee, Sourabrata, Ojha, Atul Kr., Bansal, Akanksha, Alok, Deepak, McCrae, John P., and Dušek, Ondřej
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Computer Science - Computation and Language - Abstract
Text style transfer (TST) involves altering the linguistic style of a text while preserving its core content. This paper focuses on sentiment transfer, a popular TST subtask, across a spectrum of Indian languages: Hindi, Magahi, Malayalam, Marathi, Punjabi, Odia, Telugu, and Urdu, expanding upon previous work on English-Bangla sentiment transfer (Mukherjee et al., 2023). We introduce dedicated datasets of 1,000 positive and 1,000 negative style-parallel sentences for each of these eight languages. We then evaluate the performance of various benchmark models categorized into parallel, non-parallel, cross-lingual, and shared learning approaches, including the Llama2 and GPT-3.5 large language models (LLMs). Our experiments highlight the significance of parallel data in TST and demonstrate the effectiveness of the Masked Style Filling (MSF) approach (Mukherjee et al., 2023) in non-parallel techniques. Moreover, cross-lingual and joint multilingual learning methods show promise, offering insights into selecting optimal models tailored to the specific language and task requirements. To the best of our knowledge, this work represents the first comprehensive exploration of the TST task as sentiment transfer across a diverse set of languages.
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- 2024
31. Wearable-based behaviour interpolation for semi-supervised human activity recognition
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Duan, Haoran, Wang, Shidong, Ojha, Varun, Wang, Shizheng, Huang, Yawen, Long, Yang, Ranjan, Rajiv, and Zheng, Yefeng
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Computer Science - Computer Vision and Pattern Recognition - Abstract
While traditional feature engineering for Human Activity Recognition (HAR) involves a trial-anderror process, deep learning has emerged as a preferred method for high-level representations of sensor-based human activities. However, most deep learning-based HAR requires a large amount of labelled data and extracting HAR features from unlabelled data for effective deep learning training remains challenging. We, therefore, introduce a deep semi-supervised HAR approach, MixHAR, which concurrently uses labelled and unlabelled activities. Our MixHAR employs a linear interpolation mechanism to blend labelled and unlabelled activities while addressing both inter- and intra-activity variability. A unique challenge identified is the activityintrusion problem during mixing, for which we propose a mixing calibration mechanism to mitigate it in the feature embedding space. Additionally, we rigorously explored and evaluated the five conventional/popular deep semi-supervised technologies on HAR, acting as the benchmark of deep semi-supervised HAR. Our results demonstrate that MixHAR significantly improves performance, underscoring the potential of deep semi-supervised techniques in HAR.
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- 2024
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32. Rehearsal-free Federated Domain-incremental Learning
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Sun, Rui, Duan, Haoran, Dong, Jiahua, Ojha, Varun, Shah, Tejal, and Ranjan, Rajiv
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Computer Science - Machine Learning ,Computer Science - Computer Vision and Pattern Recognition - Abstract
We introduce a rehearsal-free federated domain incremental learning framework, RefFiL, based on a global prompt-sharing paradigm to alleviate catastrophic forgetting challenges in federated domain-incremental learning, where unseen domains are continually learned. Typical methods for mitigating forgetting, such as the use of additional datasets and the retention of private data from earlier tasks, are not viable in federated learning (FL) due to devices' limited resources. Our method, RefFiL, addresses this by learning domain-invariant knowledge and incorporating various domain-specific prompts from the domains represented by different FL participants. A key feature of RefFiL is the generation of local fine-grained prompts by our domain adaptive prompt generator, which effectively learns from local domain knowledge while maintaining distinctive boundaries on a global scale. We also introduce a domain-specific prompt contrastive learning loss that differentiates between locally generated prompts and those from other domains, enhancing RefFiL's precision and effectiveness. Compared to existing methods, RefFiL significantly alleviates catastrophic forgetting without requiring extra memory space, making it ideal for privacy-sensitive and resource-constrained devices.
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- 2024
33. Dreamer XL: Towards High-Resolution Text-to-3D Generation via Trajectory Score Matching
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Miao, Xingyu, Duan, Haoran, Ojha, Varun, Song, Jun, Shah, Tejal, Long, Yang, and Ranjan, Rajiv
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Computer Science - Computer Vision and Pattern Recognition - Abstract
In this work, we propose a novel Trajectory Score Matching (TSM) method that aims to solve the pseudo ground truth inconsistency problem caused by the accumulated error in Interval Score Matching (ISM) when using the Denoising Diffusion Implicit Models (DDIM) inversion process. Unlike ISM which adopts the inversion process of DDIM to calculate on a single path, our TSM method leverages the inversion process of DDIM to generate two paths from the same starting point for calculation. Since both paths start from the same starting point, TSM can reduce the accumulated error compared to ISM, thus alleviating the problem of pseudo ground truth inconsistency. TSM enhances the stability and consistency of the model's generated paths during the distillation process. We demonstrate this experimentally and further show that ISM is a special case of TSM. Furthermore, to optimize the current multi-stage optimization process from high-resolution text to 3D generation, we adopt Stable Diffusion XL for guidance. In response to the issues of abnormal replication and splitting caused by unstable gradients during the 3D Gaussian splatting process when using Stable Diffusion XL, we propose a pixel-by-pixel gradient clipping method. Extensive experiments show that our model significantly surpasses the state-of-the-art models in terms of visual quality and performance. Code: \url{https://github.com/xingy038/Dreamer-XL}.
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- 2024
34. Impact of Dzyaloshinskii-Moriya interaction and anisotropy on topological Hall effect
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Ojha, Brindaban, Mohanty, Shaktiranjan, and Bedanta, Subhankar
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Condensed Matter - Materials Science - Abstract
Electron transport combined with magnetism has gained more attention to the spintronics community in the last few decades. Among them, the topological Hall effect, which arises due to the emergent magnetic field of a non-trivial object, is found to be a promising tool for probing a skyrmion. A sizeable interfacial Dzyaloshinskii-Moriya interaction (iDMI) with reduced effective anisotropy can stabilize skyrmions in thin films. Recently, a large iDMI has been predicted in Pt/Co/Re thin film. Thus, we have studied the effect of iDMI and anisotropy on the topological Hall effect (THE) in perpendicularly magnetized Pt/Co/X (X=Ta, Re) thin films. The presence of skyrmions is confirmed via THE as well as magnetic force microscope (MFM) imaging. Two different natures of THE signals have been explained in the two different types of samples via micromagnetic simulations. It has been found that effective anisotropy and DMI interaction contribute significantly to decide the different topological Hall behavior.
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- 2024
35. Comparing LLM prompting with Cross-lingual transfer performance on Indigenous and Low-resource Brazilian Languages
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Adelani, David Ifeoluwa, Doğruöz, A. Seza, Coneglian, André, and Ojha, Atul Kr.
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Computer Science - Computation and Language - Abstract
Large Language Models are transforming NLP for a variety of tasks. However, how LLMs perform NLP tasks for low-resource languages (LRLs) is less explored. In line with the goals of the AmericasNLP workshop, we focus on 12 LRLs from Brazil, 2 LRLs from Africa and 2 high-resource languages (HRLs) (e.g., English and Brazilian Portuguese). Our results indicate that the LLMs perform worse for the part of speech (POS) labeling of LRLs in comparison to HRLs. We explain the reasons behind this failure and provide an error analysis through examples observed in our data set., Comment: Accepted to the Americas NLP Workshop at NAACL 2024 (https://turing.iimas.unam.mx/americasnlp/2024_workshop.html)
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- 2024
36. Initial results of our spectro-photometric monitoring of XZ Tau
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Ghosh, Arpan, Sharma, Saurabh, Ninan, Joe Philip, Ojha, Devendra K., Verma, Aayushi, Sahu, Tarak Chand, Pandey, Rakesh, and Singh, Koshvendra
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Astrophysics - Solar and Stellar Astrophysics - Abstract
We present here initial results of our spectro-photometric monitoring of XZ Tau. During our monitoring period, XZ Tau exhibited several episodes of brightness variations in timescales of months at optical wavelengths in contrast to the mid-infrared wavelengths. The color evolution of XZ Tau during this period suggest that the brightness variations are driven by changes in accretion from the disc. The mid-infrared light curve shows an overall decline in brightness by $\sim$ 0.5 and 0.7 magnitude respectively in WISE W1 (3.4 $\mu$m) and W2 (4.6 $\mu$m) bands. The emission profile of the hydrogen recombination lines along with that of Ca II IRT lines points towards magnetospheric accretion of XZ Tau. We have detected P Cygni profile in H$\beta$ indicating of outflowing winds from regions close to accretion. Forbidden transitions of oxygen are also detected, likely indicating of jets originating around the central pre-main sequence star., Comment: 11 pages, 3 figures, Accepted for publication in The Bulletin de la Soci\'et\'e Royale des Sciences de Li\`ege
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- 2024
37. Accretion Funnel Reconfiguration during an Outburst in a Young Stellar Object: EX Lupi
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Singh, Koshvendra, Ninan, Joe P., Romanova, Marina M., Buckley, David A. H., Ojha, Devendra K., Ghosh, Arpan, Monson, Andrew, Schramm, Malte, Sharma, Saurabh, Reichart, Daniel E., Mikolajewska, Joanna, Beamin, Juan Carlos, Borissova, J., Ivanov, Valentin D., Kouprianov, Vladimir V., Hambsch, Franz-Josef, and Pearce, Andrew
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Astrophysics - Solar and Stellar Astrophysics - Abstract
EX Lupi, a low-mass young stellar object, went into an accretion-driven outburst in March of 2022. The outburst caused a sudden phase change of ~ 112$^{\circ}$ $\pm$ 5$^{\circ}$ in periodically oscillating multiband lightcurves. Our high resolution spectra obtained with HRS on SALT also revealed a consistent phase change in the periodically varying radial velocities, along with an increase in the radial velocity amplitude of various emission lines. The phase change and increase of radial velocity amplitude morphologically translates to a change in the azimuthal and latitudinal location of the accretion hotspot over the stellar surface, which indicates a reconfiguration of the accretion funnel geometry. Our 3D MHD simulations reproduce the phase change for EX Lupi. To explain the observations we explored the possibility of forward shifting of the dipolar accretion funnel as well as the possibility of an emergence of a new accretion funnel. During the outburst, we also found evidence of the hotspot's morphology extending azimuthally, asymmetrically with a leading hot edge and cold tail along the stellar rotation. Our high cadence photometry showed that the accretion flow has clumps. We also detected possible clumpy accretion events in the HRS spectra, that showed episodically highly blue-shifted wings in the Ca II IRT and Balmer H lines., Comment: Accepted for publication in The Astrophysical Journal
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- 2024
38. Unveiling the Cosmic Cradle: clustering and massive star formation in the enigmatic Galactic bubble N59
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Paulson, Sonu Tabitha, Mallick, K. K., and Ojha, D. K.
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Astrophysics - Astrophysics of Galaxies - Abstract
In this paper, we have conducted an investigation focused on a segment of the $Spitzer$ mid-infrared bubble N59, specifically referred to as R1 within our study. Situated in the inner Galactic plane, this region stands out for its hosting of five 6.7 GHz methanol masers, as well as numerous compact H II regions, massive clumps, filaments, and prominent bright rims. As 6.7 GHz masers are closely linked to the initial phases of high-mass star formation, exploring regions that exhibit a high abundance of these maser detections provides an opportunity to investigate relatively young massive star-forming sites. To characterize the R1 region comprehensively, we utilize multi-wavelength (archival) data from optical to radio wavelengths, together with $^{13}$CO and C$^{18}$O data. Utilizing the $Gaia$ DR3 data, we estimate the distance towards the bubble to be $4.66 \pm 0.70$ kpc. By combining near-infrared (NIR) and mid-infrared (MIR) data, we identify 12 Class I and 8 Class II sources within R1. Furthermore, spectral energy distribution (SED) analysis of selected sources reveals the presence of four embedded high-mass sources with masses ranging from 8.70-14.20 M$_\odot$. We also identified several O and B-type stars from radio continuum analysis. Our molecular study uncovers two distinct molecular clouds in the region, which, although spatially close, occupy different regions in velocity space. We also find indications of a potential hub-filament system fostering star formation within the confines of R1. Finally, we propose that the feedback from the H II regions has led to the formation of prominent Bright Rimmed Clouds (BRC) within our region of interest., Comment: 18 pages,16 figures. Accepted for publication in MNRAS
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- 2024
39. UVIT/AstroSat observation of TW Hya
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Nayak, Prasanta K., Narang, Mayank, Manoj, P., Ojha, D. K., Mathew, Blesson, Baug, T., Chandra, S., Vig, S., Maheswar, G., and Kamath, U. S.
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Astrophysics - Solar and Stellar Astrophysics - Abstract
The paper demonstrates the spectroscopic and photometric capabilities of the Ultra-Violet Imaging Telescope (UVIT) to study T-Tauri stars (TTSs). We present the first UVIT/Far-UV spectrum of a TTS, TW Hya. Based on C IV line luminosity, we estimated accretion luminosity (0.1 $L_\odot$) and mass accretion rate (2.2 $\times$ $10^{-8} M_\odot /yr$) of TW Hya, and compared these values with the accretion luminosity (0.03 $L_\odot$) and mass accretion rate (0.6 $\times$ $10^{-8} M_\odot /yr$) derived from spectral energy distribution (SED). From the SED, we derive best-fitted parameters for TW Hya: $T_{eff}$ = 3900$\pm$50 K, radius = 1.2$\pm$0.03 $R_\odot$, $\mathrm{log}\, g = 4.0$ and equivalent black-body temperatures corresponding to accretion luminosity as 14100$\pm$25 K. The parameters of TW Hya derived from UVIT observations were found to be matched well with the literature. Comparison with IUE spectra also suggests that UVIT can be used to study the spectroscopic variability of young stars. This study proposes leveraging the FUV spectroscopic capabilities of UVIT to contribute to the advancement of upcoming UV spectroscopic missions, including the Indian Spectroscopic Imaging Space Telescope (INSIST)., Comment: 9 pages, 3 figures, 2 tables
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- 2024
40. Discovery of a hot post-AGB star in Galactic globular cluster E3
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Kumar, R., Moharana, A., Piridi, S., Pradhan, A. C., Hełminiak, K. G., Ikonnikova, N., Dodin, A., Szczerba, R., Giersz, M., Ojha, D. K., and Samal, M. R.
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Astrophysics - Solar and Stellar Astrophysics ,Astrophysics - Astrophysics of Galaxies ,Astrophysics - Instrumentation and Methods for Astrophysics - Abstract
We report a new hot post-asymptotic giant branch (PAGB) star in the Galactic globular cluster (GC) E3, which is one of the first of the identified PAGB stars in a GC to show a binary signature. The star stands out as the brightest source in E3 in the \mbox{{\em Astrosat}}/UVIT images. We confirmed its membership with the cluster E3 using Gaia DR3 kinematics and parallax measurements. We supplemented the photometric observations with radial velocities (RVs) from high-resolution spectroscopic observations at two epochs and with ground- and space-based photometric observations from 0.13 $\mu$m to 22 $\mu$m. We find that the RVs vary over $\sim$6 \kms\ between the two epochs. This is an indication of the star being in a binary orbit. A simulation of possible binary systems with the observed RVs suggests a binary period of either 39.12 days or 17.83 days with mass ratio q$\geq$1.0. The [Fe/H] derived using the high-resolution spectra is $\sim -$0.7 dex, which closely matches the cluster metallicity. The spectroscopic and photometric measurements suggest \Teff\ and $\log g$ of the star as 17\,500$\pm$1\,000~K and 2.37$\pm$0.20~dex, respectively. Various PAGB evolutionary tracks on the Hertzsprung--Russell (H-R) diagram suggest a current mass of the star in the range 0.51$-$0.55 \Msun. The star is enriched with C and O abundances, showing similar CNO abundances compared to the other PAGB stars in GCs with the evidence of the third dredge-up on the AGB phase., Comment: Published in A&A Letters, Published Version
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- 2024
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41. Vibrational Dynamics and Spectroscopy of Water at Porous g-C$_{3}$N$_{4}$ and C$_{2}$N Materials
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Ojha, Deepak, Penschke, Christopher, and Saalfrank, Peter
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Physics - Chemical Physics - Abstract
In this work, the vibrational dynamics and spectroscopy of deuterated water molecules (D$_{2}$O) mimicking dense water layers at room temperature on the surfaces of two different C/N based materials with different N content and pore size, namely graphitic C$_{3}$N$_{4}$ (g-C$_{3}$N$_{4}$) and C$_{2}$N are studied using Ab Initio Molecular Dynamics (AIMD). In particular, Time-Dependent vibrational Sum-Frequency Generation spectra (TD-vSFG) of the OD modes and also time-averaged vSFG spectra and OD frequency distributions are computed., Comment: 25 pages, 7 figures
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- 2024
42. Observation of Topological Hall Effect and Skyrmions in Pt/Co/Ir/Co/Pt System
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Mohanty, Shaktiranjan, Ojha, Brindaban, Sharma, Minaxi, and Bedanta, Subhankar
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Condensed Matter - Materials Science - Abstract
The interlayer exchange coupling (IEC) between two ferromagnetic (FM) layers separated by a non-magnetic (NM) spacer layer gives rise to different types of coupling with the variation of spacer layer thickness. When the NM is metallic, the IEC is attributed to the well known Ruderman Kittel Kasuya Yosida (RKKY) interaction which shows an oscillatory decaying nature with increasing thickness. Due to this, it is possible to tune the coupling between the two FM to be either ferromagnetic or antiferromagnetic. In this work we have studied a Pt/Co/Ir/Co/Pt system where the Co thickness has been taken in the strong perpendicular magnetic anisotropy regime which is much less than the spin reorientation transition thickness. By tuning the Ir thickness to 2.0 nm, a canted state of magnetization reversal in the system is observed which gives rise to a possibility of nucleating topologically non trivial spin textures like skyrmions. Further, with the combination of transport and magnetic force microscopy (MFM) measurements, we have confirmed the presence of skyrmions in our system. These findings may be useful for potential applications in emerging spintronic and data storage technologies using skyrmions.
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- 2024
43. Sensory Neuronopathies: Clinical Presentation, Management, and Outcome
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Maniyar, Aamna, Ojha, Pawan T, Chheda, Akash, Mahto, Anuradha P, Jagiasi, Kamlesh A, Singh, Rakesh K, Singh, Rakesh, Chaudhary, Gaurav S, Kharat, Sumit, Shah, Arjun G, Gaikwad, Abhijeet, Nagendra, Shashank, and Aipu, Bilia K
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Nervous system diseases -- Diagnosis -- Care and treatment ,Immunotherapy -- Patient outcomes ,Sjogren's syndrome -- Diagnosis -- Care and treatment ,Sensory receptors -- Health aspects ,Health - Abstract
Background and Objectives: Sensory neuronopathies (SNNs) are a rare group of pure sensory disorders causing asymmetrical, multifocal pattern of sensory loss with distinct clinical and electrophysiological features. We aimed to study the clinical features and etiology and share the experience of treating SNN from our center. Methods: A prospective observational study was conducted over 3 years. Patients with predominant sensory complaints and electrophysiological evidence of neuropathy were evaluated. Possible/probable SNN was diagnosed using Camdessanch´e criteria. Detailed workup was done to determine the etiology and treatment given accordingly. Follow-up was done and response to treatment was assessed using modified Rankin Scale grading at 12 months. Results: Fourteen patients with SNN were studied. Two (14.3%) patients were diagnosed with Sjogren's syndrome (SS-SNN), two (14.3%) with paraneoplastic syndrome, one (7.1%) with leprous ganglionitis, and nine (64.3%) were idiopathic sensory neuronopathy (I-SNN) cases. Improvement occurred in nine (64.3%), stability in three (21.4%), and worsening in two (14.3%) patients. Out of 11 SS-SNN and I-SNN patients, eight showed improvement on follow-up, seven with injection rituximab (RTX) and one with azathioprine. We found positive correlation between RTX treatment and improvement on follow-up (P = 0.0256). Six (66.66%) out of nine I-SNN patients had early initiation of immunotherapy, of which all improved. There was positive correlation between early treatment initiation time in I-SNN patients and improvement (P = 0.0119). Conclusions: Promising results were noted in SS-SNN and I-SNN patients with intensive treatment approach using RTX. Hit hard and early treatment approach is crucial for achieving improvement in sensory neuronopathies. Keywords: Autoimmune, idiopathic, rituximab, sensory neuronopathy, Author(s): Aamna Maniyar (corresponding author) [1]; Pawan T Ojha [1]; Akash Chheda [1]; Anuradha P Mahto [1]; Kamlesh A Jagiasi [1]; Rakesh K Singh [1]; Rakesh Singh [1]; Gaurav S [...]
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- 2024
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44. A novel reconfigurable reduced switch multilevel inverter for renewable applications
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Sirsa, Aditya, Mittal, Arvind, and Ojha, Amit
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- 2024
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45. Smoke detection in foggy surveillance environment using parallel vision transformer network
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Chaturvedi, Shubhangi, Thakur, Poornima Singh, Khanna, Pritee, and Ojha, Aparajita
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- 2024
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46. 14N break-up α emission with 59Co, 93Nb, and 197Au targets at an incident energy of 250 MeV
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Bhuptani, C., Patel, D., Ojha, V. K., and Mukherjee, S.
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- 2024
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47. Enhancing ALPR: a two stage YOLO model with data augmentation for improved accuracy and robustness
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Bansal, Swati, Jain, Abhilasha, Sharma, Manoj, Kumar, Gautam, Ojha, Shivam, and Walia, Hemant
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- 2024
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48. Method to determine the maximum current density of p-MoS2/p-CdSe/n-WS2/n-ITO solar cell
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Pandey, Priyesh, Yadav, Shekhar, Pandey, Jai Prakash, Yadav, Rajesh Kumar, Ojha, Sandeep Kumar, and Kumar, Brijesh
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- 2024
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49. Quantifying the potential of evidence-based planting-pattern for reducing the outdoor thermal stress from a bio-meteorological perspective in tropical conditions of Indian cities
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Ojha, Saurabh Kishore, Mukherjee, Mahua, and Raje, Ar. Richa
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- 2024
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50. n-Type AlCuFeMn Medium-Entropy Alloy with Reduced Thermal Conductivity: A Prospective Thermoelectric Material
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Swarnakar, Palash, Ojha, Abhigyan, De, Partha Sarathi, Bathula, Sivaiah, and Roy, Amritendu
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- 2024
- Full Text
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