14,593 results on '"Malhotra, P"'
Search Results
2. Mapping Students' Readiness for E-Learning in Higher Education: A Bibliometric Analysis
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Anamica Maan and Kapil Malhotra
- Abstract
This paper reports the findings of a bibliometric analysis using VOSviewer on 392 Scopus database documents published from 2003 to 2022, aiming to understand the global landscape of the e-learning field and to identify the most prominent authors, institutions, countries and reference publications, as well as the research topics that have recently received the most attention in students' readiness for e-learning in Higher Education Institutions (HEIs). The findings indicate that there has been an upward trend in e-learning readiness among students in HEIs over time. Among the countries studied, the United States, Taiwan, Australia, and Malaysia were found to have the most effective approaches to addressing students' readiness for e-learning. The most highly cited author in this field is M-L. Hung. Based on the citations, the most recognised journal in this field was "Computers and Education" and the universities that were most persuasive were two Taiwan universities in the first position. The data also revealed relatively low levels of collaboration among authors, institutions and nations regarding students' readiness for e-learning.
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- 2024
3. Novel Approach for Predicting the Air Quality Index of Megacities through Attention-Enhanced Deep Multitask Spatiotemporal Learning
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Khan, Harun, Tso, Joseph, Nguyen, Nathan, Kaushal, Nivaan, Malhotra, Ansh, and Rehman, Nayel
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Computer Science - Machine Learning - Abstract
Air pollution remains one of the most formidable environmental threats to human health globally, particularly in urban areas, contributing to nearly 7 million premature deaths annually. Megacities, defined as cities with populations exceeding 10 million, are frequent hotspots of severe pollution, experiencing numerous weeks of dangerously poor air quality due to the concentration of harmful pollutants. In addition, the complex interplay of factors makes accurate air quality predictions incredibly challenging, and prediction models often struggle to capture these intricate dynamics. To address these challenges, this paper proposes an attention-enhanced deep multitask spatiotemporal machine learning model based on long-short-term memory networks for long-term air quality monitoring and prediction. The model demonstrates robust performance in predicting the levels of major pollutants such as sulfur dioxide and carbon monoxide, effectively capturing complex trends and fluctuations. The proposed model provides actionable information for policymakers, enabling informed decision making to improve urban air quality., Comment: 6 pages, 3 figures, 3 tables
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- 2024
4. Evaluating Large Language Models with fmeval
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Schwöbel, Pola, Franceschi, Luca, Zafar, Muhammad Bilal, Vasist, Keerthan, Malhotra, Aman, Shenhar, Tomer, Tailor, Pinal, Yilmaz, Pinar, Diamond, Michael, and Donini, Michele
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Computer Science - Computation and Language ,Computer Science - Machine Learning - Abstract
fmeval is an open source library to evaluate large language models (LLMs) in a range of tasks. It helps practitioners evaluate their model for task performance and along multiple responsible AI dimensions. This paper presents the library and exposes its underlying design principles: simplicity, coverage, extensibility and performance. We then present how these were implemented in the scientific and engineering choices taken when developing fmeval. A case study demonstrates a typical use case for the library: picking a suitable model for a question answering task. We close by discussing limitations and further work in the development of the library. fmeval can be found at https://github.com/aws/fmeval.
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- 2024
5. Transferring spectroscopic stellar labels to 217 million Gaia DR3 XP stars with SHBoost
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Khalatyan, A., Anders, F., Chiappini, C., Queiroz, A. B. A., Nepal, S., Ponte, M. dal, Jordi, C., Guiglion, G., Valentini, M., Elipe, G. Torralba, Steinmetz, M., Pantaleoni-González, M., Malhotra, S., Jiménez-Arranz, Ó., Enke, H., Casamiquela, L., and Ardèvol, J.
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Astrophysics - Solar and Stellar Astrophysics ,Astrophysics - Astrophysics of Galaxies ,Astrophysics - Instrumentation and Methods for Astrophysics - Abstract
We explore the feasibility of using machine-learning regression as a method of extracting basic stellar parameters and line-of-sight extinctions, given spectro-photometric data. To this end, we build a stable gradient-boosted random-forest regressor (xgboost), trained on spectroscopic data, capable of producing output parameters with reliable uncertainties from Gaia DR3 data (most notably the low-resolution XP spectra) without ground-based spectroscopic observations. Using Shapley additive explanations, we are able to interpret how the predictions for each star are influenced by each data feature. For the training and testing of the network, we use high-quality parameters obtained from the StarHorse code for a sample of around eight million stars observed by major spectroscopic surveys (APOGEE, GALAH, LAMOST, RAVE, SEGUE, and GES), complemented by curated samples of hot stars, very metal-poor stars, white dwarfs, and hot sub-dwarfs. The training data cover the whole sky, all Galactic components, and almost the full magnitude range of the Gaia DR3 XP sample of more than 217 million objects that also have parallaxes. We achieve median uncertainties (at $G\approx16$) of 0.20 mag in V-band extinction, 0.01 dex in logarithmic effective temperature, 0.20 dex in surface gravity, 0.18 dex in metallicity, and $12\%$ in mass (over the full Gaia DR3 XP sample, with considerable variations in precision as a function of magnitude and stellar type). We succeed in predicting competitive results based on Gaia DR3 XP spectra compared to classical isochrone fitting methods we employed in earlier work, especially for the parameters $A_V$, $T_{\rm eff}$, and metallicity. Finally, we showcase some applications of this new catalogue (e.g. extinction maps, metallicity trends in the Milky Way, extended maps of young massive stars, metal-poor stars, and metal-rich stars). [abridged], Comment: Submitted to A&A. 13 pages, 13 figures + references & appendices. Data available at https://data.aip.de/projects/shboost2024.html
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- 2024
6. Reverse time-to-death as time-scale in time-to-event analysis for studies of advanced illness and palliative care
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Cheung, Yin Bun, Ma, Xiangmei, Chaudhry, Isha, Liu, Nan, Zhuang, Qingyuan, Yang, Grace Meijuan, Malhotra, Chetna, and Finkelstein, Eric Andrew
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Statistics - Methodology - Abstract
Background: Incidence of adverse outcome events rises as patients with advanced illness approach end-of-life. Exposures that tend to occur near end-of-life, e.g., use of wheelchair, oxygen therapy and palliative care, may therefore be found associated with the incidence of the adverse outcomes. We propose a strategy for time-to-event analysis to mitigate the time-varying confounding. Methods: We propose a concept of reverse time-to-death (rTTD) and its use for the time-scale in time-to-event analysis. We used data on community-based palliative care uptake (exposure) and emergency department visits (outcome) among patients with advanced cancer in Singapore to illustrate. We compare the results against that of the common practice of using time-on-study (TOS) as time-scale. Results: Graphical analysis demonstrated that cancer patients receiving palliative care had higher rate of emergency department visits than non-recipients mainly because they were closer to end-of-life, and that rTTD analysis made comparison between patients at the same time-to-death. Analysis of emergency department visits in relation to palliative care using TOS time-scale showed significant increase in hazard ratio estimate when observed time-varying covariates were omitted from statistical adjustment (change-in-estimate=0.38; 95% CI 0.15 to 0.60). There was no such change in otherwise the same analysis using rTTD (change-in-estimate=0.04; 95% CI -0.02 to 0.11), demonstrating the ability of rTTD time-scale to mitigate confounding that intensifies in relation to time-to-death. Conclusion: Use of rTTD as time-scale in time-to-event analysis provides a simple and robust approach to control time-varying confounding in studies of advanced illness, even if the confounders are unmeasured., Comment: 22 pages (including 2 tables and 2 figures)
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- 2024
7. Medium-scale thermospheric gravity waves in the high-resolution Whole Atmosphere Model: Seasonal, local time, and longitudinal variations
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Malhotra, Garima, Fuller-Rowell, Timothy, Fang, Tzu-Wei, Yudin, Valery, Karol, Svetlana, Becker, Erich, and Kubaryk, Adam Marshall
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Physics - Space Physics ,Physics - Atmospheric and Oceanic Physics ,Physics - Data Analysis, Statistics and Probability ,Physics - Geophysics ,Physics - Plasma Physics - Abstract
This paper presents a study of the global medium-scale (scales<620 km) gravity wave (GW) activity (in terms of zonal wind variance) and its seasonal, local time and longitudinal variations by employing the enhanced-resolution (~50 km) Whole Atmosphere Model (WAMT254) and space-based observations for geomagnetically quiet conditions. It is found that the GW hotspots produced by WAMT254 in the troposphere and stratosphere agree well with previously well-studied orographic and non-orographic sources. In the ionosphere-thermosphere (IT) region, GWs spread out forming latitudinal band-like hotspots. During solstices, a primary maximum in GW activity is observed in WAMT254 and GOCE over winter mid-high latitudes, likely associated with higher-order waves with primary sources in polar night jet, fronts and polar vortex. During all the seasons, the enhancement of GWs around the geomagnetic poles as observed by GOCE (at ~250 km) is well captured by simulations. WAMT254 GWs in the IT region also show dependence on local time due to their interaction with migrating tides leading to diurnal and semidiurnal variations. The GWs are more likely to propagate up from the MLT region during westward/weakly-eastward phase of thermospheric tides, signifying the dominance of eastward GW momentum flux in the MLT. Additionally, as a novel finding, a wavenumber-4 signature in GW activity is predicted by WAMT254 between 6-12 LT in the tropics at ~250 km, which propagates eastward with local time. This behavior is likely associated with the modulation of GWs by wave-4 signal of non-migrating tides in the lower thermospheric zonal winds.
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- 2024
8. Double Mpemba effect in the cooling of trapped colloids
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Malhotra, Isha and Löwen, Hartmut
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Condensed Matter - Soft Condensed Matter - Abstract
The Mpemba effect describes the phenomenon that a system at a hot initial temperature cools faster than at an initial warm temperature in the same environment. Such an anomalous cooling has recently been predicted and realized for trapped colloids. Here, we investigate the freezing behavior of a passive colloidal particle by employing numerical Brownian dynamics simulations and theoretical calculations with a model that can be directly tested in experiments. During the cooling process, the colloidal particle exhibits multiple non-monotonic regimes in cooling rates, with the cooling time decreasing twice as a function of the initial temperature-an unexpected phenomenon we refer to as the Double Mpemba effect. Additionally, we demonstrate that both the Mpemba and Double Mpemba effects can be predicted by various machine learning methods, which expedite the analysis of complex, computationally intensive systems.
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- 2024
9. Chandra detects low-luminosity AGN with $M_\mathrm{BH}=10^{4}-10^{6}~M_\mathrm{\odot}$ in nearby ($z<0.5$), dwarf and star-forming galaxies
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Singha, Mainak, Sarmiento, Julissa, Malhotra, Sangeeta, Rhoads, James E., Yung, L. Y. Aaron, Wang, Junxian, Zheng, Zhen-Ya, Lin, Ruqiu, Kim, Keunho, Kang, Jialai, and Harish, Santosh
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Astrophysics - Astrophysics of Galaxies - Abstract
We searched the Chandra and XMM archives for observations of 900 green pea galaxies to find AGN signatures. Green peas are low-mass galaxies with prominent emission lines, similar in size and star formation rate to high-redshift dwarf galaxies. Of the 29 observations found, 9 show X-ray detections with $S/N>3$. The 2-10 keV X-ray luminosity for these 9 sources exceeds $10^{40}~\mathrm{erg~s}^{-1}$, with 2 sources exceeding $10^{41}~\mathrm{erg~s}^{-1}$, suggesting the presence of intermediate-mass black holes (IMBH) or low-luminosity AGN (LLAGN) with BH masses between $100-10^6M_\mathrm{\odot}$. All X-ray detected sources (plus 6 additional sources) show He~II$\lambda4686$ emission and a broad component of the H$\alpha$ emission line, indicating winds. The line widths of the broad H$\alpha$ and He II$\lambda4686$ emitting gas clouds are weakly correlated ($R^{2}=0.15$), suggesting He II$\lambda4686$ emission is inconsistent with winds from super-Eddington accretors. However, the ratio of X-ray luminosity to star formation rate shows an anti-correlation with metallicity in 5 out of 9 X-ray detected sources, implying ultraluminous X-ray sources are key contributors to the observed X-ray luminosity. This could be due to super-Eddington accretors or IMBH. The X-ray emission is much higher than that produced by Wolf-Rayet stars and supernovae-driven winds. Thus, the X-ray luminosity in these 9 sources can only be explained by black holes with masses over $100~M_\mathrm{\odot}$. Our findings suggest the presence of LLAGN in these galaxies, with broad H$\alpha$ line widths implying BH masses of $10^4-10^6M_\mathrm{\odot}$. Given Green Peas' role as significant Lyman Continuum leakers, LLAGN in these galaxies could have contributed significantly to cosmic reionization., Comment: Submitted to ApJ. 17 pages, 11 figures and 3 tables. Comments welcome
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- 2024
10. Memory Faults in Activation-sparse Quantized Deep Neural Networks: Analysis and Mitigation using Sharpness-aware Training
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Malhotra, Akul and Gupta, Sumeet Kumar
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Computer Science - Machine Learning - Abstract
Improving the hardware efficiency of deep neural network (DNN) accelerators with techniques such as quantization and sparsity enhancement have shown an immense promise. However, their inference accuracy in non-ideal real-world settings (such as in the presence of hardware faults) is yet to be systematically analyzed. In this work, we investigate the impact of memory faults on activation-sparse quantized DNNs (AS QDNNs). We show that a high level of activation sparsity comes at the cost of larger vulnerability to faults, with AS QDNNs exhibiting up to 11.13% lower accuracy than the standard QDNNs. We establish that the degraded accuracy correlates with a sharper minima in the loss landscape for AS QDNNs, which makes them more sensitive to perturbations in the weight values due to faults. Based on this observation, we employ sharpness-aware quantization (SAQ) training to mitigate the impact of memory faults. The AS and standard QDNNs trained with SAQ have up to 19.50% and 15.82% higher inference accuracy, respectively compared to their conventionally trained equivalents. Moreover, we show that SAQ-trained AS QDNNs show higher accuracy in faulty settings than standard QDNNs trained conventionally. Thus, sharpness-aware training can be instrumental in achieving sparsity-related latency benefits without compromising on fault tolerance., Comment: arXiv admin note: substantial text overlap with arXiv:2301.00675
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- 2024
11. Logical Distillation of Graph Neural Networks
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Pluska, Alexander, Welke, Pascal, Gärtner, Thomas, and Malhotra, Sagar
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Computer Science - Machine Learning ,Computer Science - Artificial Intelligence - Abstract
We present a logic based interpretable model for learning on graphs and an algorithm to distill this model from a Graph Neural Network (GNN). Recent results have shown connections between the expressivity of GNNs and the two-variable fragment of first-order logic with counting quantifiers (C2). We introduce a decision-tree based model which leverages an extension of C2 to distill interpretable logical classifiers from GNNs. We test our approach on multiple GNN architectures. The distilled models are interpretable, succinct, and attain similar accuracy to the underlying GNN. Furthermore, when the ground truth is expressible in C2, our approach outperforms the GNN., Comment: Fixed errors in the statement of Theorem 1
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- 2024
12. Towards a Personal Health Large Language Model
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Cosentino, Justin, Belyaeva, Anastasiya, Liu, Xin, Furlotte, Nicholas A., Yang, Zhun, Lee, Chace, Schenck, Erik, Patel, Yojan, Cui, Jian, Schneider, Logan Douglas, Bryant, Robby, Gomes, Ryan G., Jiang, Allen, Lee, Roy, Liu, Yun, Perez, Javier, Rogers, Jameson K., Speed, Cathy, Tailor, Shyam, Walker, Megan, Yu, Jeffrey, Althoff, Tim, Heneghan, Conor, Hernandez, John, Malhotra, Mark, Stern, Leor, Matias, Yossi, Corrado, Greg S., Patel, Shwetak, Shetty, Shravya, Zhan, Jiening, Prabhakara, Shruthi, McDuff, Daniel, and McLean, Cory Y.
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Computer Science - Artificial Intelligence ,Computer Science - Computation and Language - Abstract
In health, most large language model (LLM) research has focused on clinical tasks. However, mobile and wearable devices, which are rarely integrated into such tasks, provide rich, longitudinal data for personal health monitoring. Here we present Personal Health Large Language Model (PH-LLM), fine-tuned from Gemini for understanding and reasoning over numerical time-series personal health data. We created and curated three datasets that test 1) production of personalized insights and recommendations from sleep patterns, physical activity, and physiological responses, 2) expert domain knowledge, and 3) prediction of self-reported sleep outcomes. For the first task we designed 857 case studies in collaboration with domain experts to assess real-world scenarios in sleep and fitness. Through comprehensive evaluation of domain-specific rubrics, we observed that Gemini Ultra 1.0 and PH-LLM are not statistically different from expert performance in fitness and, while experts remain superior for sleep, fine-tuning PH-LLM provided significant improvements in using relevant domain knowledge and personalizing information for sleep insights. We evaluated PH-LLM domain knowledge using multiple choice sleep medicine and fitness examinations. PH-LLM achieved 79% on sleep and 88% on fitness, exceeding average scores from a sample of human experts. Finally, we trained PH-LLM to predict self-reported sleep quality outcomes from textual and multimodal encoding representations of wearable data, and demonstrate that multimodal encoding is required to match performance of specialized discriminative models. Although further development and evaluation are necessary in the safety-critical personal health domain, these results demonstrate both the broad knowledge and capabilities of Gemini models and the benefit of contextualizing physiological data for personal health applications as done with PH-LLM., Comment: 72 pages
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- 2024
13. Transforming Wearable Data into Health Insights using Large Language Model Agents
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Merrill, Mike A., Paruchuri, Akshay, Rezaei, Naghmeh, Kovacs, Geza, Perez, Javier, Liu, Yun, Schenck, Erik, Hammerquist, Nova, Sunshine, Jake, Tailor, Shyam, Ayush, Kumar, Su, Hao-Wei, He, Qian, McLean, Cory Y., Malhotra, Mark, Patel, Shwetak, Zhan, Jiening, Althoff, Tim, McDuff, Daniel, and Liu, Xin
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Computer Science - Artificial Intelligence ,Computer Science - Computation and Language - Abstract
Despite the proliferation of wearable health trackers and the importance of sleep and exercise to health, deriving actionable personalized insights from wearable data remains a challenge because doing so requires non-trivial open-ended analysis of these data. The recent rise of large language model (LLM) agents, which can use tools to reason about and interact with the world, presents a promising opportunity to enable such personalized analysis at scale. Yet, the application of LLM agents in analyzing personal health is still largely untapped. In this paper, we introduce the Personal Health Insights Agent (PHIA), an agent system that leverages state-of-the-art code generation and information retrieval tools to analyze and interpret behavioral health data from wearables. We curate two benchmark question-answering datasets of over 4000 health insights questions. Based on 650 hours of human and expert evaluation we find that PHIA can accurately address over 84% of factual numerical questions and more than 83% of crowd-sourced open-ended questions. This work has implications for advancing behavioral health across the population, potentially enabling individuals to interpret their own wearable data, and paving the way for a new era of accessible, personalized wellness regimens that are informed by data-driven insights., Comment: 38 pages
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- 2024
14. Measuring the circular polarization of gravitational waves with pulsar timing arrays
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Cruz, N. M. Jiménez, Malhotra, Ameek, Tasinato, Gianmassimo, and Zavala, Ivonne
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Astrophysics - Cosmology and Nongalactic Astrophysics ,General Relativity and Quantum Cosmology - Abstract
The circular polarization of the stochastic gravitational wave background (SGWB) is a key observable for characterising the origin of the signal detected by Pulsar Timing Array (PTA) collaborations. Both the astrophysical and the cosmological SGWB can have a sizeable amount of circular polarization, due to Poisson fluctuations in the source properties for the former, and to parity violating processes in the early universe for the latter. Its measurement is challenging since PTA are blind to the circular polarization monopole, forcing us to turn to anisotropies for detection. We study the sensitivity of current and future PTA datasets to circular polarization anisotropies, focusing on realistic modelling of intrinsic and kinematic anisotropies for astrophysical and cosmological scenarios respectively. Our results indicate that the expected level of circular polarization for the astrophysical SGWB should be within the reach of near future datasets, while for cosmological SGWB circular polarization is a viable target for more advanced SKA-type experiments., Comment: 28 pages, 9 figures
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- 2024
15. Asteroid Kamo`oalewa's journey from the lunar Giordano Bruno crater to Earth 1:1 resonance
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Jiao, Yifei, Cheng, Bin, Huang, Yukun, Asphaug, Erik, Gladman, Brett, Malhotra, Renu, Michel, Patrick, Yu, Yang, and Baoyin, Hexi
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Astrophysics - Earth and Planetary Astrophysics - Abstract
Among the nearly 30,000 known near-Earth asteroids (NEAs), only tens of them possess Earth co-orbital characteristics with semi-major axes $\sim$1 au. In particular, 469219 Kamo`oalewa (2016 HO3), upcoming target of China's Tianwen-2 asteroid sampling mission, exhibits a meta-stable 1:1 mean-motion resonance with Earth. Intriguingly, recent ground-based observations show that Kamo`oalewa has spectroscopic characteristics similar to space-weathered lunar silicates, hinting at a lunar origin instead of an asteroidal one like the vast majority of NEAs. Here we use numerical simulations to demonstrate that Kamo`oalewa's physical and orbital properties are compatible with a fragment from a crater larger than 10--20 km formed on the Moon in the last few million years. The impact could have ejected sufficiently large fragments into heliocentric orbits, some of which could be transferred to Earth 1:1 resonance and persist today. This leads us to suggest the young lunar crater Giordano Bruno (22 km diameter, 1--10 Ma age) as the most likely source, linking a specific asteroid in space to its source crater on the Moon. The hypothesis will be tested by the Tianwen-2 mission when it returns a sample of Kamo`oalewa. And the upcoming NEO Surveyor mission will possibly help us to identify such a lunar-derived NEA population., Comment: 29 pages, 4 figures. Published in Nature Astronomy, 19 April 2024
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- 2024
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16. Cosmological constraints on curved quintessence
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Bhattacharya, Sukannya, Borghetto, Giulia, Malhotra, Ameek, Parameswaran, Susha, Tasinato, Gianmassimo, and Zavala, Ivonne
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Astrophysics - Cosmology and Nongalactic Astrophysics ,General Relativity and Quantum Cosmology ,High Energy Physics - Theory - Abstract
Dynamical dark energy has gained renewed interest due to recent theoretical and observational developments. In the present paper, we focus on a string-motivated dark energy set-up, and perform a detailed cosmological analysis of exponential quintessence with potential $V=V_0 e^{-\lambda\phi}$, allowing for non-zero spatial curvature. We first gain some physical intuition into the full evolution of such a scenario by analysing the corresponding dynamical system. Then, we test the model using a combination of Planck CMB data, DESI BAO data, as well as recent supernovae datasets. For the model parameter $\lambda$, we obtain a preference for nonzero values: $\lambda = 0.48^{+0.28}_{-0.21},\; 0.68^{+0.31}_{-0.20},\; 0.77^{+0.18}_{-0.15}$ at 68% C.L. when combining CMB+DESI with Pantheon+, Union3 and DES-Y5 supernovae datasets respectively. We find no significant hint for spatial curvature. We discuss the implications of current cosmological results for the exponential quintessence model, and more generally for dark energy in string theory., Comment: 34 pages, 13 figures, 10 tables. Comments welcome! V2 - updated plots and added references
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- 2024
17. Towards Counting Markov Equivalence Classes with Logical Constraints
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Bizzaro, Davide, Serafini, Luciano, and Malhotra, Sagar
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Computer Science - Logic in Computer Science - Abstract
We initiate the study of counting Markov Equivalence Classes (MEC) under logical constraints. MECs are equivalence classes of Directed Acyclic Graphs (DAGs) that encode the same conditional independence structure among the random variables of a DAG model. Observational data can only allow to infer a DAG model up to Markov Equivalence. However, Markov equivalent DAGs can represent different causal structures, potentially super-exponentially many. Hence, understanding MECs combinatorially is critical to understanding the complexity of causal inference. In this paper, we focus on analysing MECs of size one, with logical constraints on the graph topology. We provide a polynomial-time algorithm (w.r.t. the number of nodes) for enumerating essential DAGs (the only members of an MEC of size one) with arbitrary logical constraints expressed in first-order logic with two variables and counting quantifiers (C^2). Our work brings together recent developments in tractable first-order model counting and combinatorics of MECs., Comment: Under Review
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- 2024
18. Repelling Planet pairs by Ping-pong Scattering
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Wu, Yanqin, Malhotra, Renu, and Lithwick, Yoram
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Astrophysics - Earth and Planetary Astrophysics ,Astrophysics - Astrophysics of Galaxies - Abstract
The Kepler mission reveals a peculiar trough-peak feature in the orbital spacing of close-in planets near mean-motion resonances: a deficit and an excess that are a couple percent to the narrow, respectively wide, of the resonances. This feature has received two main classes of explanations, one involving eccentricity damping, the other scattering with small bodies. Here, we point out a few issues with the damping scenario, and study the scattering scenario in more detail. We elucidate why scattering small bodies tends to repel two planets. As the small bodies random-walk in energy and angular momentum space, they tend to absorb, fractionally, more energy than angular momentum. This, which we call "ping-pong repulsion", transports angular momentum from the inner to the outer planet and pushes the two planets apart. Such a process, even if ubiquitous, leaves identifiable marks only near first-order resonances: diverging pairs jump across the resonance quickly and produce the MMR asymmetry. To explain the observed positions of the trough-peaks, a total scattering mass of order a few percent of the planet masses is required. Moreover, if this mass is dominated by a handful of Mercury-sized bodies, one can also explain the planet eccentricities as inferred from transit-time-variations. Lastly, we suggest how these conditions may have naturally arisen during the late stages of planet formation., Comment: 14 pages, submitted to AAS journal
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- 2024
19. Inflationary Gravitational Wave Spectral Shapes as test for Low-Scale Leptogenesis
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Borboruah, Zafri A., Ghoshal, Anish, Malhotra, Lekhika, and Yajnik, Urjit
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High Energy Physics - Phenomenology ,Astrophysics - Cosmology and Nongalactic Astrophysics ,General Relativity and Quantum Cosmology ,High Energy Physics - Theory - Abstract
We study thermal and non-thermal resonant leptogenesis in a general setting where a heavy scalar $\phi$ decays to right-handed neutrinos (RHNs) whose further out-of-equilibrium decay generates the required lepton asymmetry. Domination of the energy budget of the Universe by the $\phi$ or the RHNs alters the evolution history of the primordial gravitational waves (PGW), of inflationary origin, which re-enter the horizon after inflation, modifying the spectral shape. The decays of $\phi$ and RHNs release entropy into the early Universe while nearly degenerate RHNs facilitate low and intermediate scale leptogenesis. We show that depending on the coupling $y_R$ of $\phi$ to radiation species, RHNs can achieve thermal abundance before decaying, which gives rise to thermal leptogenesis. A characteristic damping of the GW spectrum resulting in two knee-like features or one knee-like feature would provide evidence for low-scale thermal and non-thermal leptogenesis respectively. We explore the parameter space for the lightest right-handed neutrino mass $M_1\in[10^2,10^{14}]$ GeV and washout parameter $K$ that depends on the light-heavy neutrino Yukawa couplings $\lambda$, in the weak ($K < 1$) and strong ($K > 1$) washout regimes. The resulting novel features compatible with observed baryon asymmetry are detectable by future experiments like LISA and ET. By estimating signal-to-noise ratio (SNR) for upcoming GW experiments, we investigate the effect of the scalar mass $M_\phi$ and reheating temperature $T_\phi$, which depends on the $\phi-N$ Yukawa couplings $y_N$., Comment: 57 pages, 21 figures
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- 2024
20. Machine Learning Assisted Dynamical Classification of Trans-Neptunian Objects
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Volk, Kathryn and Malhotra, Renu
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Astrophysics - Earth and Planetary Astrophysics ,Astrophysics - Instrumentation and Methods for Astrophysics ,Computer Science - Machine Learning - Abstract
Trans-Neptunian objects (TNOs) are small, icy bodies in the outer solar system. They are observed to have a complex orbital distribution that was shaped by the early dynamical history and migration of the giant planets. Comparisons between the different dynamical classes of modeled and observed TNOs can help constrain the history of the outer solar system. Because of the complex dynamics of TNOs, particularly those in and near mean motion resonances with Neptune, classification has traditionally been done by human inspection of plots of the time evolution of orbital parameters. This is very inefficient. The Vera Rubin Observatory's Legacy Survey of Space and Time (LSST) is expected to increase the number of known TNOs by a factor of $\sim$10, necessitating a much more automated process. In this chapter we present an improved supervised machine learning classifier for TNOs. Using a large and diverse training set as well as carefully chosen, dynamically motivated data features calculated from numerical integrations of TNO orbits, our classifier returns results that match those of a human classifier 98% of the time, and dynamically relevant classifications 99.7% of the time. This classifier is dramatically more efficient than human classification, and it will improve classification of both observed and modeled TNO data., Comment: Accepted chapter to appear in the Elsevier book "Machine Learning for Small Solar System Bodies", edited by Valerio Carruba, Evgeny Smirnov, and Dagmara Oszkiewicz
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- 2024
21. UniDEC : Unified Dual Encoder and Classifier Training for Extreme Multi-Label Classification
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Kharbanda, Siddhant, Gupta, Devaansh, K, Gururaj, Malhotra, Pankaj, Hsieh, Cho-Jui, and Babbar, Rohit
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Computer Science - Machine Learning ,Computer Science - Artificial Intelligence - Abstract
Extreme Multi-label Classification (XMC) involves predicting a subset of relevant labels from an extremely large label space, given an input query and labels with textual features. Models developed for this problem have conventionally used modular approach with (i) a Dual Encoder (DE) to embed the queries and label texts, (ii) a One-vs-All classifier to rerank the shortlisted labels mined through meta-classifier training. While such methods have shown empirical success, we observe two key uncharted aspects, (i) DE training typically uses only a single positive relation even for datasets which offer more, (ii) existing approaches fixate on using only OvA reduction of the multi-label problem. This work aims to explore these aspects by proposing UniDEC, a novel end-to-end trainable framework which trains the dual encoder and classifier in together in a unified fashion using a multi-class loss. For the choice of multi-class loss, the work proposes a novel pick-some-label (PSL) reduction of the multi-label problem with leverages multiple (in come cases, all) positives. The proposed framework achieves state-of-the-art results on a single GPU, while achieving on par results with respect to multi-GPU SOTA methods on various XML benchmark datasets, all while using 4-16x lesser compute and being practically scalable even beyond million label scale datasets.
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- 2024
22. Developing a novel mobile application for cognitive behavioral therapy for insomnia for people with schizophrenia: integration of wearable and environmental sleep sensors
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Jeon, Jae Min, Ma, Junhua, Kwak, Paulyn, Dang, Bing, Buleje, Italo, Ancoli-Israel, Sonia, Malhotra, Atul, and Lee, Ellen E
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Biomedical and Clinical Sciences ,Clinical Sciences ,Brain Disorders ,Sleep Research ,Schizophrenia ,Bioengineering ,Behavioral and Social Science ,Mental Illness ,Mental Health ,Clinical Research ,Clinical Trials and Supportive Activities ,Serious Mental Illness ,Rehabilitation ,Networking and Information Technology R&D (NITRD) ,Mind and Body ,Mental health ,Good Health and Well Being ,Humans ,Sleep Initiation and Maintenance Disorders ,Mobile Applications ,Cognitive Behavioral Therapy ,Wearable Electronic Devices ,Digital health technology ,Application development ,Sensors ,Psychology ,Respiratory System ,Clinical sciences - Abstract
BackgroundPeople with serious mental illnesses (SMIs) have three-fold higher rates of comorbid insomnia than the general population, which has downstream effects on cognitive, mental, and physical health. Cognitive Behavioral Therapy for Insomnia (CBT-i) is a safe and effective first-line treatment for insomnia, though the therapy's effectiveness relies on completing nightly sleep diaries which can be challenging for some people with SMI and comorbid cognitive deficits. Supportive technologies such as mobile applications and sleep sensors may aid with completing sleep diaries. However, commercially available CBT-i apps are not designed for individuals with cognitive deficits. To aid with this challenge, we have developed an integrated mobile application, named "Sleep Catcher," that will automatically incorporate data from a wearable fitness tracker and a bed sensor to track nightly sleep duration, overnight awakenings, bed-times, and wake-times to generate nightly sleep diaries for CBT-i.MethodsThe application development process will be described-writing algorithms to generating useful data, creating a clinician web portal to oversee patients and the mobile application, and integrating sleep data from device platforms and user input.ResultsThe mobile and web applications were developed using Flutter, IBM Code Engine, and IBM Cloudant database. The mobile application was developed with a user-centered approach and incremental changes informed by a series of beta tests. Special user-interface features were considered to address the challenges of developing a simple and effective mobile application targeting people with SMI.ConclusionThere is strong potential for synergy between engineering and mental health expertise to develop technologies for specific clinical populations. Digital health technologies allow for the development of multi-disciplinary solutions to existing health disparities in vulnerable populations, particularly in people with SMI.
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- 2024
23. Prediction of Readmission Following Sepsis Using Social Determinants of Health.
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Amrollahi, Fatemeh, Kennis, Brent, Shashikumar, Supreeth, Taylor, Stephanie, Ford, James, Rodriguez, Arianna, Weston, Julia, Maheshwary, Romir, Nemati, Shamim, Wardi, Gabriel, Meier, Angela, and Malhotra, Atul
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Humans ,Patient Readmission ,Female ,Male ,Social Determinants of Health ,Retrospective Studies ,Middle Aged ,Sepsis ,Aged ,Adult ,United States ,Logistic Models ,Risk Factors ,Cohort Studies - Abstract
OBJECTIVES: To determine the predictive value of social determinants of health (SDoH) variables on 30-day readmission following a sepsis hospitalization as compared with traditional clinical variables. DESIGN: Multicenter retrospective cohort study using patient-level data, including demographic, clinical, and survey data. SETTINGS: Thirty-five hospitals across the United States from 2017 to 2021. PATIENTS: Two hundred seventy-one thousand four hundred twenty-eight individuals in the AllofUs initiative, of which 8909 had an index sepsis hospitalization. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Unplanned 30-day readmission to the hospital. Multinomial logistic regression models were constructed to account for survival in determination of variables associate with 30-day readmission and are presented as adjusted odds rations (aORs). Of the 8909 sepsis patients in our cohort, 21% had an unplanned hospital readmission within 30 days. Median age (interquartile range) was 54 years (41-65 yr), 4762 (53.4%) were female, and there were self-reported 1612 (18.09%) Black, 2271 (25.49%) Hispanic, and 4642 (52.1%) White individuals. In multinomial logistic regression models accounting for survival, we identified that change to nonphysician provider type due to economic reasons (aOR, 2.55 [2.35-2.74]), delay of receiving medical care due to lack of transportation (aOR, 1.68 [1.62-1.74]), and inability to afford flow-up care (aOR, 1.59 [1.52-1.66]) were strongly and independently associated with a 30-day readmission when adjusting for survival. Patients who lived in a ZIP code with a high percentage of patients in poverty and without health insurance were also more likely to be readmitted within 30 days (aOR, 1.26 [1.22-1.29] and aOR, 1.28 [1.26-1.29], respectively). Finally, we found that having a primary care provider and health insurance were associated with low odds of an unplanned 30-day readmission. CONCLUSIONS: In this multicenter retrospective cohort, several SDoH variables were strongly associated with unplanned 30-day readmission. Models predicting readmission following sepsis hospitalization may benefit from the addition of SDoH factors to traditional clinical variables.
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- 2024
24. The effects of Facebook and Instagram on the 2020 election: A deactivation experiment.
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Allcott, Hunt, Gentzkow, Matthew, Mason, Winter, Wilkins, Arjun, Barberá, Pablo, Brown, Taylor, Cisneros, Juan, Crespo-Tenorio, Adriana, Dimmery, Drew, Freelon, Deen, González-Bailón, Sandra, Guess, Andrew, Kim, Young, Lazer, David, Malhotra, Neil, Moehler, Devra, Nair-Desai, Sameer, Nait El Barj, Houda, Nyhan, Brendan, Paixao de Queiroz, Ana, Pan, Jennifer, Settle, Jaime, Thorson, Emily, Tromble, Rebekah, Velasco Rivera, Carlos, Wittenbrink, Benjamin, Zahedian, Saam, Franco, Annie, Kiewiet de Jonge, Chad, Stroud, Natalie, Tucker, Joshua, and Wojcieszak, Magdalena
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Facebook ,Instagram ,election ,polarization ,social media ,Politics ,Humans ,Social Media ,United States ,Attitude ,Male ,Female - Abstract
We study the effect of Facebook and Instagram access on political beliefs, attitudes, and behavior by randomizing a subset of 19,857 Facebook users and 15,585 Instagram users to deactivate their accounts for 6 wk before the 2020 U.S. election. We report four key findings. First, both Facebook and Instagram deactivation reduced an index of political participation (driven mainly by reduced participation online). Second, Facebook deactivation had no significant effect on an index of knowledge, but secondary analyses suggest that it reduced knowledge of general news while possibly also decreasing belief in misinformation circulating online. Third, Facebook deactivation may have reduced self-reported net votes for Trump, though this effect does not meet our preregistered significance threshold. Finally, the effects of both Facebook and Instagram deactivation on affective and issue polarization, perceived legitimacy of the election, candidate favorability, and voter turnout were all precisely estimated and close to zero.
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- 2024
25. Association Between Sleep Apnea Treatment and Health Care Resource Use in Patients With Atrial Fibrillation
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Sterling, Kimberly L, Alpert, Naomi, Malik, Anita S, Pépin, Jean‐Louis, Benjafield, Adam V, Malhotra, Atul, Piccini, Jonathan P, Cistulli, Peter A, Nunez, Carlos M, Barrett, Meredith, and Armitstead, Jeff
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Biomedical and Clinical Sciences ,Cardiovascular Medicine and Haematology ,Clinical Sciences ,Heart Disease ,Clinical Research ,Health Services ,Sleep Research ,Lung ,Cardiovascular ,Good Health and Well Being ,Humans ,Female ,Atrial Fibrillation ,Male ,Middle Aged ,Retrospective Studies ,Aged ,Sleep Apnea ,Obstructive ,Continuous Positive Airway Pressure ,United States ,Health Resources ,Health Care Costs ,Hospitalization ,Patient Compliance ,Treatment Outcome ,adherence ,atrial fibrillation ,health care resource use ,obstructive sleep apnea ,positive airway pressure ,medXcloud group ** ,Cardiorespiratory Medicine and Haematology ,Cardiovascular medicine and haematology - Abstract
BackgroundObstructive sleep apnea (OSA) contributes to the generation, recurrence, and perpetuation of atrial fibrillation, and it is associated with worse outcomes. Little is known about the economic impact of OSA therapy in atrial fibrillation. This retrospective cohort study assessed the impact of positive airway pressure (PAP) therapy adherence on health care resource use and costs in patients with OSA and atrial fibrillation.Methods and resultsInsurance claims data for ≥1 year before sleep testing and 2 years after device setup were linked with objective PAP therapy use data. PAP adherence was defined from an extension of the US Medicare 90-day definition. Inverse probability of treatment weighting was used to create covariate-balanced PAP adherence groups to mitigate confounding. Of 5867 patients (32% women; mean age, 62.7 years), 41% were adherent, 38% were intermediate, and 21% were nonadherent. Mean±SD number of all-cause emergency department visits (0.61±1.21 versus 0.77±1.55 [P=0.023] versus 0.95±1.90 [P
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- 2024
26. Mandibular Jaw Movement Automated Analysis for Oral Appliance Monitoring in Obstructive Sleep Apnea: A Prospective Cohort Study
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Pépin, Jean-Louis, Cistulli, Peter A, Crespeigne, Etienne, Tamisier, Renaud, Bailly, Sébastien, Bruwier, Annick, Le-Dong, Nhat-Nam, Lavigne, Gilles, Malhotra, Atul, and Martinot, Jean-Benoît
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Biomedical and Clinical Sciences ,Cardiovascular Medicine and Haematology ,Dental/Oral and Craniofacial Disease ,Sleep Research ,Clinical Research ,Lung ,Humans ,Sleep Apnea ,Obstructive ,Prospective Studies ,Male ,Polysomnography ,Female ,Middle Aged ,Adult ,Mandible ,Aged ,Continuous Positive Airway Pressure ,Movement ,Monitoring ,Physiologic ,mandibular advancement device ,OSA ,oral appliance titration ,artificial intelligence ,mandibular jaw movements ,Cardiovascular medicine and haematology ,Clinical sciences - Abstract
Rationale: Oral appliances are second-line treatments after continuous positive airway pressure for obstructive sleep apnea (OSA) management. However, the need for oral appliance titration limits their use as a result of monitoring challenges to assess the treatment effect on OSA. Objectives: To assess the validity of mandibular jaw movement (MJM) automated analysis compared with polysomnography (PSG) and polygraphy (PG) in evaluating the effect of oral appliance treatment and the effectiveness of MJM monitoring for oral appliance titration at home in patients with OSA. Methods: This observational, prospective study included 135 patients with OSA eligible for oral appliance therapy. The primary outcome was the apnea-hypopnea index (AHI), measured through in-laboratory PSG/PG and MJM-based technology. Additionally, MJM monitoring at home was conducted at regular intervals during the titration process. The agreement between PSG/PG and MJM automated analysis was revaluated using Bland-Altman analysis. Changes in AHI during the home-based oral appliance titration process were evaluated using a generalized linear mixed model and a generalized estimating equation model. Results: The automated MJM analysis demonstrated strong agreement with PG in assessing AHI at the end of titration, with a median bias of 0.24/h (limits of agreement, -11.2 to 12.8/h). The improvement of AHI from baseline in response to oral appliance treatment was consistent across three evaluation conditions: in-laboratory PG (-59.6%; 95% confidence interval, -59.8% to -59.5%), in-laboratory automated MJM analysis (-59.2%; -65.2% to -52.2%), and at-home automated MJM analysis (-59.7%; -67.4% to -50.2%). Conclusions: Incorporating MJM automated analysis into the oral appliance titration process has the potential to optimize oral appliance therapy outcomes for OSA.
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- 2024
27. Differences between Stable and Unstable Architectures of Compact Planetary Systems
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Volk, Kathryn and Malhotra, Renu
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Astrophysics - Earth and Planetary Astrophysics - Abstract
We present a stability analysis of a large set of simulated planetary systems of three or more planets based on architectures of multiplanet systems discovered by \textit{Kepler} and \textit{K2}. We propagated 21,400 simulated planetary systems up to 5 billion orbits of the innermost planet; approximately 13% of these simulations ended in a planet-planet collision within that timespan. We examined trends in dynamical stability based on dynamical spacings, orbital period ratios, and mass ratios of nearest-neighbor planets as well as the system-wide planet mass distribution and the spectral fraction describing the system's short-term evolution. We find that instability is more likely in planetary systems with adjacent planet pairs that have period ratios less than two and in systems of greater variance of planet masses. Systems with planet pairs at very small dynamical spacings (less than $\sim10-12$ mutual Hill radius) are also prone to instabilities, but instabilities also occur at much larger planetary separations. We find that a large spectral fraction (calculated from short integrations) is a reasonable predictor of longer-term dynamical instability; systems that have a large number of Fourier components in their eccentricity vectors are prone to secular chaos and subsequent eccentricity growth and instabilities., Comment: accepted for publication in AJ
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- 2024
28. MindSet: Vision. A toolbox for testing DNNs on key psychological experiments
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Biscione, Valerio, Yin, Dong, Malhotra, Gaurav, Dujmovic, Marin, Montero, Milton L., Puebla, Guillermo, Adolfi, Federico, Heaton, Rachel F., Hummel, John E., Evans, Benjamin D., Habashy, Karim, and Bowers, Jeffrey S.
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Computer Science - Computer Vision and Pattern Recognition ,Computer Science - Artificial Intelligence - Abstract
Multiple benchmarks have been developed to assess the alignment between deep neural networks (DNNs) and human vision. In almost all cases these benchmarks are observational in the sense they are composed of behavioural and brain responses to naturalistic images that have not been manipulated to test hypotheses regarding how DNNs or humans perceive and identify objects. Here we introduce the toolbox MindSet: Vision, consisting of a collection of image datasets and related scripts designed to test DNNs on 30 psychological findings. In all experimental conditions, the stimuli are systematically manipulated to test specific hypotheses regarding human visual perception and object recognition. In addition to providing pre-generated datasets of images, we provide code to regenerate these datasets, offering many configurable parameters which greatly extend the dataset versatility for different research contexts, and code to facilitate the testing of DNNs on these image datasets using three different methods (similarity judgments, out-of-distribution classification, and decoder method), accessible at https://github.com/MindSetVision/mindset-vision. We test ResNet-152 on each of these methods as an example of how the toolbox can be used.
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- 2024
29. Direct, simple, and efficient computation of all components of the virtual-casing magnetic field in axisymmetric geometries with Kapur-Rokhlin quadrature
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Toler, Evan, Cerfon, Antoine, and Malhotra, Dhairya
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Physics - Plasma Physics - Abstract
In a recent publication (Toler et al. 2023), we demonstrated that for axisymmetric geometries, the Kapur-Rokhlin quadrature rule provided an efficient and high-order accurate method for computing the normal component, on the plasma surface, of the magnetic field due to the toroidal current flowing in the plasma, via the virtual-casing principle. The calculation was indirect, as it required the prior computation of the magnetic vector potential from the virtual-casing principle, followed by the computation of its tangential derivative by Fourier differentiation, in order to obtain the normal component of the magnetic field. Our approach did not provide the other components of the virtual-casing magnetic field. In this letter, we show that a more direct and more general approach is available for the computation of the virtual-casing magnetic field. The Kapur-Rokhlin quadrature rule accurately calculates the principal value integrals in the expression for all the components of the magnetic field on the plasma boundary, and the numerical error converges at a rate nearly as high as the indirect method we presented previously., Comment: 14 pages, 6 figures
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- 2024
30. Towards Inclusive Video Commenting: Introducing Signmaku for the Deaf and Hard-of-Hearing
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Chen, Si, Cheng, Haocong, Situ, Jason, Kirst, Desirée, Su, Suzy, Malhotra, Saumya, Angrave, Lawrence, Wang, Qi, and Huang, Yun
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Computer Science - Human-Computer Interaction ,F.2.2 ,I.2.7 - Abstract
Previous research underscored the potential of danmaku--a text-based commenting feature on videos--in engaging hearing audiences. Yet, for many Deaf and hard-of-hearing (DHH) individuals, American Sign Language (ASL) takes precedence over English. To improve inclusivity, we introduce "Signmaku," a new commenting mechanism that uses ASL, serving as a sign language counterpart to danmaku. Through a need-finding study (N=12) and a within-subject experiment (N=20), we evaluated three design styles: real human faces, cartoon-like figures, and robotic representations. The results showed that cartoon-like signmaku not only entertained but also encouraged participants to create and share ASL comments, with fewer privacy concerns compared to the other designs. Conversely, the robotic representations faced challenges in accurately depicting hand movements and facial expressions, resulting in higher cognitive demands on users. Signmaku featuring real human faces elicited the lowest cognitive load and was the most comprehensible among all three types. Our findings offered novel design implications for leveraging generative AI to create signmaku comments, enriching co-learning experiences for DHH individuals., Comment: 14 pages, CHI 2024
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- 2024
31. Understanding Domain-Size Generalization in Markov Logic Networks
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Chen, Florian, Weitkämper, Felix, and Malhotra, Sagar
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Computer Science - Artificial Intelligence ,Computer Science - Machine Learning - Abstract
We study the generalization behavior of Markov Logic Networks (MLNs) across relational structures of different sizes. Multiple works have noticed that MLNs learned on a given domain generalize poorly across domains of different sizes. This behavior emerges from a lack of internal consistency within an MLN when used across different domain sizes. In this paper, we quantify this inconsistency and bound it in terms of the variance of the MLN parameters. The parameter variance also bounds the KL divergence between an MLN's marginal distributions taken from different domain sizes. We use these bounds to show that maximizing the data log-likelihood while simultaneously minimizing the parameter variance corresponds to two natural notions of generalization across domain sizes. Our theoretical results apply to Exponential Random Graphs and other Markov network based relational models. Finally, we observe that solutions known to decrease the variance of the MLN parameters, like regularization and Domain-Size Aware MLNs, increase the internal consistency of the MLNs. We empirically verify our results on four different datasets, with different methods to control parameter variance, showing that controlling parameter variance leads to better generalization., Comment: To Appear in Proceedings of ECML 2024-Research Track
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- 2024
32. Who Uses Personas in Requirements Engineering: The Practitioners' Perspective
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Wang, Yi, Arora, Chetan, Liu, Xiao, Hoang, Thuong, Malhotra, Vasudha, Cheng, Ben, and Grundy, John
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Computer Science - Software Engineering - Abstract
Personas are commonly used in software projects to gain a better understanding of end-users' needs. However, there is a limited understanding of their usage and effectiveness in practice. This paper presents the results of a two-step investigation, comprising interviews with 26 software developers, UI/UX designers, business analysts and product managers and a survey of 203 practitioners, aimed at shedding light on the current practices, methods and challenges of using personas in software development. Our findings reveal variations in the frequency and effectiveness of personas across different software projects and IT companies, the challenges practitioners face when using personas and the reasons for not using them at all. Furthermore, we investigate the coverage of human aspects in personas, often assumed to be a key feature of persona descriptions. Contrary to the general perception, our study shows that human aspects are often ignored for various reasons in personas or requirements engineering in general. Our study provides actionable insights for practitioners to overcome challenges in using personas during requirements engineering stages, and we identify areas for future research.
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- 2024
33. On the Metallicity Gradients in the Galactic Disk using Open Clusters
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Joshi, Yogesh C., Deepak, and Malhotra, Sagar
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Astrophysics - Astrophysics of Galaxies - Abstract
We study the metallicity distribution and evolution in the Galactic disk based on the largest sample of open star clusters in the Galaxy. From the catalogue of 1879 open clusters in the range of Galactocentric distance (R_GC) from 4 to 20 kpc, we investigate the variation of metallicity in the Galactic disk as functions of R_GC, vertical distance (Z), and ages of the clusters. In the direction perpendicular to the Galactic plane, variation in metallicity is found to follow a stepped linear relation. We estimate a vertical metallicity gradient d[Fe/H]/dZ of -0.545+/-0.046 dex/kpc for |Z| < 0.487 kpc, and -0.075+/-0.093 dex/kpc for 0.487 < |Z| < 1.8 kpc. On average, metallicity variations above and below the Galactic plane are found to change at similar rates. The change in metallicity in the radial direction is also found to follow a two-function linear relation. We obtain a radial metallicity gradient d[Fe/H]/d[R_GC] of -0.070+/-0.002 dex/kpc for 4.0
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- 2024
34. Beyond the Mean: Testing Consumer Rationality through Higher Moments of Demand
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Maes, Sebastiaan and Malhotra, Raghav
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Economics - Theoretical Economics - Abstract
We study a setting where an analyst has access to purely aggregate information about the consumption choices of a heterogenous population of individuals. We show that observing the statistical moments of market demand allows the analyst to test aggregate data for rationality. Interestingly, just the mean and variance of demand carry observable restrictions. This is in stark contrast to impossibility result of the Sonnenschein-Mantel-Debreu theorem, which shows that aggregate demand carries no observable restrictions at all. We leverage our approach to deliver a characterization of rationality in terms of moments for the common two-good case. We illustrate the usefulness of moment-based restrictions through two applications: (i) improving the precision of demand and welfare estimates; and (ii) testing for the existence of a welfare-relevant representative consumer., Comment: arXiv admin note: substantial text overlap with arXiv:2303.01231
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- 2024
35. Summary Paper: Use Case on Building Collaborative Safe Autonomous Systems-A Robotdog for Guiding Visually Impaired People
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Malhotra, Aman and Saidi, Selma
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Computer Science - Robotics ,Computer Science - Artificial Intelligence ,Computer Science - Distributed, Parallel, and Cluster Computing ,Computer Science - Multiagent Systems ,Electrical Engineering and Systems Science - Systems and Control - Abstract
This is a summary paper of a use case of a Robotdog dedicated to guide visually impaired people in complex environment like a smart intersection. In such scenarios, the Robotdog has to autonomously decide whether it is safe to cross the intersection or not in order to further guide the human. We leverage data sharing and collaboration between the Robotdog and other autonomous systems operating in the same environment. We propose a system architecture for autonomous systems through a separation of a collaborative decision layer, to enable collective decision making processes, where data about the environment, relevant to the Robotdog decision, together with evidences for trustworthiness about other systems and the environment are shared.
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- 2024
36. Measuring kinematic anisotropies with pulsar timing arrays
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Cruz, N. M. Jiménez, Malhotra, Ameek, Tasinato, Gianmassimo, and Zavala, Ivonne
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General Relativity and Quantum Cosmology ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
Recent Pulsar Timing Array (PTA) collaborations show strong evidence for a stochastic gravitational wave background (SGWB) with the characteristic Hellings-Downs inter-pulsar correlations. The signal may stem from supermassive black hole binary mergers, or early universe phenomena. The former is expected to be strongly anisotropic while primordial backgrounds are likely to be predominantly isotropic with small fluctuations. In case the observed SGWB is of cosmological origin, our relative motion with respect to the SGWB rest frame is a guaranteed source of anisotropy, leading to $\textit{O}(10^{-3})$ energy density fluctuations of the SGWB. For such cosmological SGWB, kinematic anisotropies are likely to be larger than the intrinsic anisotropies, akin to the cosmic microwave background (CMB) dipole anisotropy. We assess the sensitivity of current PTA data to the kinematic dipole anisotropy, and we also forecast at what extent the magnitude and direction of the kinematic dipole can be measured in the future with an SKA-like experiment. We also discuss how the spectral shape of the SGWB and the location of the pulsars to monitor affect the prospects of detecting the kinematic dipole with PTA. In the future, a detection of this anisotropy may even help resolve the discrepancy in the magnitude of the kinematic dipole as measured by CMB and large-scale structure observations., Comment: 29 pages, 6 figures. V2: corrected upper limit, updated forecasts
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- 2024
37. Simple and Effective Transfer Learning for Neuro-Symbolic Integration
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Daniele, Alessandro, Campari, Tommaso, Malhotra, Sagar, and Serafini, Luciano
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Computer Science - Machine Learning ,Computer Science - Artificial Intelligence - Abstract
Deep Learning (DL) techniques have achieved remarkable successes in recent years. However, their ability to generalize and execute reasoning tasks remains a challenge. A potential solution to this issue is Neuro-Symbolic Integration (NeSy), where neural approaches are combined with symbolic reasoning. Most of these methods exploit a neural network to map perceptions to symbols and a logical reasoner to predict the output of the downstream task. These methods exhibit superior generalization capacity compared to fully neural architectures. However, they suffer from several issues, including slow convergence, learning difficulties with complex perception tasks, and convergence to local minima. This paper proposes a simple yet effective method to ameliorate these problems. The key idea involves pretraining a neural model on the downstream task. Then, a NeSy model is trained on the same task via transfer learning, where the weights of the perceptual part are injected from the pretrained network. The key observation of our work is that the neural network fails to generalize only at the level of the symbolic part while being perfectly capable of learning the mapping from perceptions to symbols. We have tested our training strategy on various SOTA NeSy methods and datasets, demonstrating consistent improvements in the aforementioned problems., Comment: Accepted as full paper at the International Conference on Neural-Symbolic Learning and Reasoning (NeSy 2024)
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- 2024
38. A lack of LAEs within 5Mpc of a luminous quasar in an overdensity at z=6.9: potential evidence of quasar negative feedback at protocluster scales
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Lambert, Trystan S., Assef, R. J., Mazzucchelli, C., Bañados, E., Aravena, M., Barrientos, F., González-López, J., Hu, W., Infante, L., Malhotra, S., Moya-Sierralta, C., Rhoads, J., Valdes, F., Wang, J., Wold, I. G. B., and Zheng, Z.
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Astrophysics - Astrophysics of Galaxies - Abstract
High-redshift quasars are thought to live in the densest regions of space which should be made evident by an overdensity of galaxies around them. However, campaigns to identify these overdensities through the search of Lyman Break Galaxies (LBGs) and Lyman $\alpha$ emitters (LAEs) have had mixed results. These may be explained by either the small field of view of some of the experiments, the broad redshift ranges targeted by LBG searches, and by the inherent large uncertainty of quasar redshifts estimated from UV emission lines, which makes it difficult to place the Ly-$\alpha$ emission line within a narrowband filter. Here we present a three square degree search ($\sim 1000$ pMpc) for LAEs around the $z=6.9$ quasar VIKJ2348-3054 using the Dark Energy CAMera (DECam), housed on the 4m Blanco telescope, finding 38 LAEs. The systemic redshift of VIK J2348--3054 is known from ALMA [CII] observations and place the Ly-$\alpha$ emission line of companions within the NB964 narrowband of DECam. This is the largest field of view LAE search around a $z>6$ quasar conducted to date. We find that this field is $\sim$ 10 times more overdense when compared to the Chandra Deep-Field South, observed previously with the same instrumental setup as well as several combined blank fields. This is strong evidence that VIKJ2348-3054 resides in an overdensity of LAEs over several Mpc. Surprisingly, we find a lack of LAEs within 5 physical Mpc of the quasar and take this to most likely be evidence of the quasar suppressing star formation in its immediate vicinity. This result highlights the importance of performing overdensity searches over large areas to properly assess the density of those regions of the Universe., Comment: Accepted to A&A. 17 pages, 11 figures
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- 2024
39. Pharmacogenetic guided versus standard warfarin dosing for routine clinical care with its pharmacoeconomic impact: a randomized controlled clinical trial
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Anand, Aishwarya, Hegde, Naveen C, Chhabra, Pulkit, Purohit, Jai, Kumar, Rupesh, Gupta, Ankur, Lad, Deepesh P, Mohindra, Ritin, Mehrotra, Saurabh, Vijayvergiya, Rajesh, Kumar, Basant, Sharma, Vishal, Malhotra, Pankaj, Ahluwalia, Jasmina, Das, Reena, Patil, Amol N, Shafiq, Nusrat, and Malhotra, Samir
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- 2024
- Full Text
- View/download PDF
40. Rapid and mass multiplication of three peppermint (Mentha piperita L.) Collections through In vitro Propagation
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Sidhu, G S, Malhotra, P K, and Menon, Rohit
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- 2019
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41. Effects of drinking water defluoridation on mineral and haemato-biochemical status in fluorotic buffaloes
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Singh, S.T., Dua, K., Singh, R., Malhotra, P., Bansal, B.K., Randhawa, C.S., and Uppal, S.K.
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- 2018
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42. Supporting WFN Collective Social Entrepreneurship through Social Movement Learning and Critical Participatory Action Research
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Sarah M. Ray, Jessica Hinshaw, Chitvan Trivedi, and Gayatri Malhotra
- Abstract
The purpose of this conceptual paper is to explore the complexities and connections between women, femme, and nonbinary (WFN) collective social entrepreneurs, social movement learning (SML), and critical participatory action research (CPAR) within the fields of adult education (AE) and human resource development (HRD). WFN collective social entrepreneurship serves as a reaction and solution to system failures, by creating supportive learning environments. We discuss the potential of social movement learning (SML) in these collectives, offering marginalized learners opportunities for skill development, knowledge sharing, and social impact efforts. This paper proposes using CPAR as a research approach to support social movements and amplify marginalized voices. CPAR can illuminate the development and learning networks of WFN social entrepreneur collectives and emphasize the importance of inclusive and intersectional approaches in entrepreneurial education and research within AE/HRD.
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- 2024
- Full Text
- View/download PDF
43. Potential Therapeutic Targets in Obesity, Sleep Apnea, Diabetes, and Fatty Liver Disease.
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Gu, Christina, Bernstein, Nicole, Mittal, Nikita, Kurnool, Soumya, Schwartz, Hannah, Loomba, Rohit, and Malhotra, Atul
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CPAP ,GIP ,GLP-1 ,MASLD ,NAFLD ,OSA ,bariatric surgery ,diabetes ,glucagon ,hepatic steatosis ,metabolic syndrome ,obesity - Abstract
Obesity and metabolic syndrome affect the majority of the US population. Patients with obesity are at increased risk of developing type 2 diabetes (T2DM), obstructive sleep apnea (OSA), and metabolic dysfunction-associated steatotic liver disease (MASLD), each of which carry the risk of further complications if left untreated and lead to adverse outcomes. The rising prevalence of obesity and its comorbidities has led to increased mortality, decreased quality of life, and rising healthcare expenditures. This phenomenon has resulted in the intensive investigation of exciting therapies for obesity over the past decade, including more treatments that are still in the pipeline. In our present report, we aim to solidify the relationships among obesity, T2DM, OSA, and MASLD through a comprehensive review of current research. We also provide an overview of the surgical and pharmacologic treatment classes that target these relationships, namely bariatric surgery, the glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), and glucagon receptor agonists.
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- 2024
44. Ransomware Cyberattack Associated With Cardiac Arrest Incidence and Outcomes at Untargeted, Adjacent Hospitals.
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Pham, Thaidan, Loo, Theoren, Malhotra, Atul, Longhurst, Christopher, Hylton, Diana, Dameff, Christian, Tully, Jeffrey, Wardi, Gabriel, Sell, Rebecca, and Pearce, Alex
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cardiac arrest ,cyberattack ,cybersecurity ,outcomes ,ransomware - Abstract
OBJECTIVES: Healthcare ransomware cyberattacks have been associated with major regional hospital disruptions, but data reporting patient-oriented outcomes in critical conditions such as cardiac arrest (CA) are limited. This study examined the CA incidence and outcomes of untargeted hospitals adjacent to a ransomware-infected healthcare delivery organization (HDO). DESIGN SETTING AND PATIENTS: This cohort study compared the CA incidence and outcomes of two untargeted academic hospitals adjacent to an HDO under a ransomware cyberattack during the pre-attack (April 3-30, 2021), attack (May 1-28, 2021), and post-attack (May 29, 2021-June 25, 2021) phases. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Emergency department and hospital mean daily census, number of CAs, mean daily CA incidence per 1,000 admissions, return of spontaneous circulation, survival to discharge, and survival with favorable neurologic outcome were measured. The study evaluated 78 total CAs: 44 out-of-hospital CAs (OHCAs) and 34 in-hospital CAs. The number of total CAs increased from the pre-attack to attack phase (21 vs. 38; p = 0.03), followed by a decrease in the post-attack phase (38 vs. 19; p = 0.01). The number of total CAs exceeded the cyberattack month forecast (May 2021: 41 observed vs. 27 forecasted cases; 95% CI, 17.0-37.4). OHCA cases also exceeded the forecast (May 2021: 24 observed vs. 12 forecasted cases; 95% CI, 6.0-18.8). Survival with favorable neurologic outcome rates for all CAs decreased, driven by increases in OHCA mortality: survival with favorable neurologic rates for OHCAs decreased from the pre-attack phase to attack phase (40.0% vs. 4.5%; p = 0.02) followed by an increase in the post-attack phase (4.5% vs. 41.2%; p = 0.01). CONCLUSIONS: Untargeted hospitals adjacent to ransomware-infected HDOs may see worse outcomes for patients suffering from OHCA. These findings highlight the critical need for cybersecurity disaster planning and resiliency.
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- 2024
45. Functional EPAS1/HIF2A missense variant is associated with hematocrit in Andean highlanders
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Lawrence, Elijah S, Gu, Wanjun, Bohlender, Ryan J, Anza-Ramirez, Cecilia, Cole, Amy M, Yu, James J, Hu, Hao, Heinrich, Erica C, O’Brien, Katie A, Vasquez, Carlos A, Cowan, Quinn T, Bruck, Patrick T, Mercader, Kysha, Alotaibi, Mona, Long, Tao, Hall, James E, Moya, Esteban A, Bauk, Marco A, Reeves, Jennifer J, Kong, Mitchell C, Salem, Rany M, Vizcardo-Galindo, Gustavo, Macarlupu, Jose-Luis, Figueroa-Mujíca, Rómulo, Bermudez, Daniela, Corante, Noemi, Gaio, Eduardo, Fox, Keolu P, Salomaa, Veikko, Havulinna, Aki S, Murray, Andrew J, Malhotra, Atul, Powel, Frank L, Jain, Mohit, Komor, Alexis C, Cavalleri, Gianpiero L, Huff, Chad D, Villafuerte, Francisco C, and Simonson, Tatum S
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Biological Sciences ,Genetics ,Clinical Research ,2.1 Biological and endogenous factors ,Aetiology ,Humans ,Adaptation ,Physiological ,Altitude ,East Asian People ,Hematocrit ,Hypoxia ,Mutation ,Missense ,South American People - Abstract
Hypoxia-inducible factor pathway genes are linked to adaptation in both human and nonhuman highland species. EPAS1, a notable target of hypoxia adaptation, is associated with relatively lower hemoglobin concentration in Tibetans. We provide evidence for an association between an adaptive EPAS1 variant (rs570553380) and the same phenotype of relatively low hematocrit in Andean highlanders. This Andean-specific missense variant is present at a modest frequency in Andeans and absent in other human populations and vertebrate species except the coelacanth. CRISPR-base-edited human cells with this variant exhibit shifts in hypoxia-regulated gene expression, while metabolomic analyses reveal both genotype and phenotype associations and validation in a lowland population. Although this genocopy of relatively lower hematocrit in Andean highlanders parallels well-replicated findings in Tibetans, it likely involves distinct pathway responses based on a protein-coding versus noncoding variants, respectively. These findings illuminate how unique variants at EPAS1 contribute to the same phenotype in Tibetans and a subset of Andean highlanders despite distinct evolutionary trajectories.
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- 2024
46. CPAP resumption after a first termination and impact on all-cause mortality in France
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Pépin, Jean-Louis, Tamisier, Renaud, Benjafield, Adam V, Rinder, Pierre, Lavergne, Florent, Josseran, Anne, Sinel-Boucher, Paul, Cistulli, Peter A, Malhotra, Atul, Hornus, Pierre, and Bailly, Sébastien
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Biomedical and Clinical Sciences ,Cardiovascular Medicine and Haematology ,Clinical Research ,Lung ,Sleep Research ,Good Health and Well Being ,Adult ,Humans ,Male ,Adolescent ,Continuous Positive Airway Pressure ,Patient Compliance ,Hypertension ,Sleep Apnea ,Obstructive ,France ,medXcloud group ,Medical and Health Sciences ,Respiratory System ,Cardiovascular medicine and haematology - Abstract
BackgroundContinuation of continuous positive airway pressure (CPAP) therapy after initial prescription has been shown to reduce all-cause mortality versus therapy termination. However, there is a lack of data on the rates and impact of resuming CPAP in patients with obstructive sleep apnoea (OSA). This analysis determined the prevalence of CPAP resumption in the year after termination, characterised determinants of CPAP resumption, and examined the impact of CPAP resumption on all-cause mortality.MethodsFrench national health insurance reimbursement system data for adults aged ≥18 years were used. CPAP prescription was identified by specific treatment codes. Patients who resumed CPAP after first therapy termination and continued to use CPAP for 1 year were matched with those who resumed CPAP then terminated therapy for a second time.ResultsOut of 103 091 individuals with a first CPAP termination, 26% resumed CPAP over the next 12 months, and 65% of these were still using CPAP 1 year later. Significant predictors of CPAP continuation after resumption included male sex, hypertension and CPAP prescription by a pulmonologist. In the matched population, the risk of all-cause death was 38% lower in individuals who continued using CPAP after therapy resumption versus those who had a second therapy discontinuation (hazard ratio 0.62, 95% CI 0.48-0.79; p=0.0001).ConclusionThese data suggest that individuals with OSA who fail initial therapy with CPAP should be offered a second trial with the device to ensure that effective therapy is not withheld from those who might benefit.
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- 2024
47. Functional magnetic resonance imaging in schizophrenia: current evidence, methodological advances, limitations and future directions.
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Voineskos, Aristotle, Hawco, Colin, Neufeld, Nicholas, Turner, Jessica, Ameis, Stephanie, Anticevic, Alan, Buchanan, Robert, Cadenhead, Kristin, Dazzan, Paola, Dickie, Erin, Gallucci, Julia, Lahti, Adrienne, Malhotra, Anil, Öngür, Dost, Lencz, Todd, Sarpal, Deepak, and Oliver, Lindsay
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Schizophrenia ,biomarkers ,clinical utility ,cognition ,functional magnetic resonance imaging ,functional outcomes ,negative symptoms ,precision medicine ,therapeutic mechanisms ,treatment response - Abstract
Functional neuroimaging emerged with great promise and has provided fundamental insights into the neurobiology of schizophrenia. However, it has faced challenges and criticisms, most notably a lack of clinical translation. This paper provides a comprehensive review and critical summary of the literature on functional neuroimaging, in particular functional magnetic resonance imaging (fMRI), in schizophrenia. We begin by reviewing research on fMRI biomarkers in schizophrenia and the clinical high risk phase through a historical lens, moving from case-control regional brain activation to global connectivity and advanced analytical approaches, and more recent machine learning algorithms to identify predictive neuroimaging features. Findings from fMRI studies of negative symptoms as well as of neurocognitive and social cognitive deficits are then reviewed. Functional neural markers of these symptoms and deficits may represent promising treatment targets in schizophrenia. Next, we summarize fMRI research related to antipsychotic medication, psychotherapy and psychosocial interventions, and neurostimulation, including treatment response and resistance, therapeutic mechanisms, and treatment targeting. We also review the utility of fMRI and data-driven approaches to dissect the heterogeneity of schizophrenia, moving beyond case-control comparisons, as well as methodological considerations and advances, including consortia and precision fMRI. Lastly, limitations and future directions of research in the field are discussed. Our comprehensive review suggests that, in order for fMRI to be clinically useful in the care of patients with schizophrenia, research should address potentially actionable clinical decisions that are routine in schizophrenia treatment, such as which antipsychotic should be prescribed or whether a given patient is likely to have persistent functional impairment. The potential clinical utility of fMRI is influenced by and must be weighed against cost and accessibility factors. Future evaluations of the utility of fMRI in prognostic and treatment response studies may consider including a health economics analysis.
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- 2024
48. Access challenges to opioid use disorder treatment among individuals experiencing homelessness: Voices from the streets
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Hsu, Michael, Jung, Olivia S, Kwan, Li Ting, Jegede, Oluwole, Martin, Bianca, Malhotra, Aniket, and Suzuki, Joji
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Clinical and Health Psychology ,Psychology ,Brain Disorders ,Clinical Research ,Drug Abuse (NIDA only) ,Substance Misuse ,Behavioral and Social Science ,Prescription Drug Abuse ,Mental health ,Good Health and Well Being ,Medications for opioid use disorder ,Buprenorphine ,Health equity ,Treatment access ,Opioid use disorder ,Public Health and Health Services ,Substance Abuse ,Health services and systems ,Clinical and health psychology - Abstract
BackgroundAchieving equitable access to medications for opioid use disorder (MOUD) such as buprenorphine is a pressing issue. Evidence suggests disparities in MOUD access based on race and socioeconomic status, further exacerbated by the COVID-19 pandemic. However, the drivers behind this access gap remain poorly understood. This study explores barriers to treatment access among individuals with opioid use disorder (OUD) experiencing homelessness.MethodsWe interviewed 28 individuals in and around the Boston Public Health Commission (BPHC) Engagement Center, an area known for its high density of active substance use and homelessness. We asked about people's experiences, perceptions, and attitudes toward OUD treatment. We conducted a thematic analysis of our interview data.ResultsFifty-four percent of participants sampled were not prescribed MOUD. None of the participants reported having an active prescription of sublingual buprenorphine or buprenorphine/naloxone. White participants were more likely to have been prescribed buprenorphine in the past compared to participants of other races even in this socioeconomically homogeneous sample. Themes that emerged in our data included challenges to accessing MOUD due to reduced services during the COVID-19 pandemic, lost or stolen medications, fewer inpatient withdrawal management beds for women, transportation challenges, fear of adverse effects of MOUD, the perception that taking MOUD replaces one addiction for another, and community disapproval of MOUD. Participants also reported stigma and discrimination based on race, gender, and socioeconomic status.ConclusionSystems and individual-level factors contribute to the MOUD treatment gap across race and socioeconomic status. The COVID-19 pandemic posed additional access challenges. This study provides important, actionable insights about the barriers faced by a particularly vulnerable population of individuals with OUD experiencing homelessness.
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- 2024
49. Safe Mission-Level Path Planning for Exploration of Lunar Shadowed Regions by a Solar-Powered Rover
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Lamarre, Olivier, Malhotra, Shantanu, and Kelly, Jonathan
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Computer Science - Robotics - Abstract
Exploration of the lunar south pole with a solar-powered rover is challenging due to the highly dynamic solar illumination conditions and the presence of permanently shadowed regions (PSRs). In turn, careful planning in space and time is essential. Mission-level path planning is a global, spatiotemporal paradigm that addresses this challenge, taking into account rover resources and mission requirements. However, existing approaches do not proactively account for random disturbances, such as recurring faults, that may temporarily delay rover traverse progress. In this paper, we formulate a chance-constrained mission-level planning problem for the exploration of PSRs by a solar-powered rover affected by random faults. The objective is to find a policy that visits as many waypoints of scientific interest as possible while respecting an upper bound on the probability of mission failure. Our approach assumes that faults occur randomly, but at a known, constant average rate. Each fault is resolved within a fixed time, simulating the recovery period of an autonomous system or the time required for a team of human operators to intervene. Unlike solutions based upon dynamic programming alone, our method breaks the chance-constrained optimization problem into smaller offline and online subtasks to make the problem computationally tractable. Specifically, our solution combines existing mission-level path planning techniques with a stochastic reachability analysis component. We find mission plans that remain within reach of safety throughout large state spaces. To empirically validate our algorithm, we simulate mission scenarios using orbital terrain and illumination maps of Cabeus Crater. Results from simulations of multi-day, long-range drives in the LCROSS impact region are also presented., Comment: Accepted to the IEEE Aerospace Conference (AERO'24), Big Sky, Montana, March 2-9, 2024
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- 2024
50. TREASUREHUNT: Transients and Variability Discovered with HST in the JWST North Ecliptic Pole Time Domain Field
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O'Brien, Rosalia, Jansen, Rolf A., Grogin, Norman A., Cohen, Seth H., Smith, Brent M., Silver, Ross M., Maksym III, W. P., Windhorst, Rogier A., Carleton, Timothy, Koekemoer, Anton M., Hathi, Nimish P., Willmer, Christopher N. A., Frye, Brenda L., Alpaslan, M., Ashby, M. L. N., Ashcraft, T. A., Bonoli, S., Brisken, W., Cappelluti, N., Civano, F., Conselice, C. J., Dhillon, V. S., Driver, S. P., Duncan, K. J., Dupke, R., Elvis, M., Fazio, G. G., Finkelstein, S. L., Gim, H. B., Griffiths, A., Hammel, H. B., Hyun, M., Im, M., Jones, V. R., Kim, D., Ladjelate, B., Larson, R. L., Malhotra, S., Marshall, M. A., Milam, S. N., Pierel, J. D. R., Rhoads, J. E., Rodney, S. A., Röttgering, H. J. A., Rutkowski, M. J., Ryan, Jr., R. E., Ward, M. J., White, C. W., van Weeren, R. J., Zhao, X., Summers, J., D'Silva, J. C. J., Ortiz III, R., Robotham, A. S. G., Coe, D., Nonino, M., Pirzkal, N., Yan, H., and Acharya, T.
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Astrophysics - Astrophysics of Galaxies - Abstract
The JWST North Ecliptic Pole (NEP) Time Domain Field (TDF) is a $>$14 arcmin diameter field optimized for multi-wavelength time-domain science with JWST. It has been observed across the electromagnetic spectrum both from the ground and from space, including with the Hubble Space Telescope (HST). As part of HST observations over 3 cycles (the "TREASUREHUNT" program), deep images were obtained with ACS/WFC in F435W and F606W that cover almost the entire JWST NEP TDF. Many of the individual pointings of these programs partially overlap, allowing an initial assessment of the potential of this field for time-domain science with HST and JWST. The cumulative area of overlapping pointings is ~88 arcmin$^2$, with time intervals between individual epochs that range between 1 day and 4$+$ years. To a depth of $m_{AB}$ $\simeq$ 29.5 mag (F606W), we present the discovery of 12 transients and 190 variable candidates. For the variable candidates, we demonstrate that Gaussian statistics are applicable, and estimate that ~80 are false positives. The majority of the transients will be supernovae, although at least two are likely quasars. Most variable candidates are AGN, where we find 0.42% of the general $z$ $<$ 6 field galaxy population to vary at the $~3\sigma$ level. Based on a 5-year timeframe, this translates into a random supernova areal density of up to ~0.07 transients per arcmin$^2$ (~245 deg$^{-2}$) per epoch, and a variable AGN areal density of ~1.25 variables per arcmin$^2$ (~4500 deg$^{-2}$) to these depths., Comment: 32 pages, 11 figures, 5 tables, 1 Appendix
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- 2024
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