113,728 results on '"A Shrestha"'
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2. Long-term reduced tillage and winter cover crops can improve soil quality without depleting moisture
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A Gomes, A DeVincentis, S Solis, D Zaccaria, D Munk, K Bali, A Shrestha, K Gould, and J Mitchell
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Agriculture - Abstract
California farmers who use reduced-disturbance tillage and winter cover cropping can boost production and improve soil health. However, some farmers are hesitant to try these conservation practices due to uncertainty about whether planting winter cover crops will deplete soil moisture in already drought-stricken regions. Our study addresses these concerns by looking at how long-term reduced-disturbance tillage and winter cover cropping, compared to fallowed soils with standard tillage, affected soil moisture. Although we found a statistical difference in total soil water content, the difference was only about 0.3 inches of water per foot of soil. On average, the soil water content of the top 0–96 inches was highest for the reduced-disturbance fields with winter cover crops. This was especially evident during our driest field season, from November 1, 2017, to March 15, 2018, when cumulative rainfall was only 1.9 inches. Our findings show that winter cover cropping and reduced-disturbance tillage can improve soil without depleting soil water levels in row crops.
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- 2023
- Full Text
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3. An Exploration of Effects of Dark Mode on University Students: A Human Computer Interface Analysis
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Shrestha, Awan, Shrestha, Sabil, Paneru, Biplov, Paneru, Bishwash, Paudel, Sansrit, Adhikari, Ashish, and Sapkota, Sanjog Chhetri
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Computer Science - Human-Computer Interaction ,Computer Science - Computational Engineering, Finance, and Science - Abstract
This research dives into exploring the dark mode effects on students of a university. Research is carried out implementing the dark mode in e-Learning sites and its impact on behavior of the users. Students are spending more time in front of the screen for their studies especially after the pandemic. The blue light from the screen during late hours affects circadian rhythm of the body which negatively impacts the health of humans including eye strain and headache. The difficulty that students faced during the time of interacting with various e-Learning sites especially during late hours was analyzed using different techniques of HCI like survey, interview, evaluation methods and principles of design. Dark mode is an option which creates a pseudo inverted adaptable interface by changing brighter elements of UI into a dim-lit friendly environment. It is said that using dark mode will lessen the amount of blue light emitted and benefit students who suffer from eye strain. Students' interactions with dark mode were investigated using a survey, and an e-learning site with a dark mode theme was created. Based on the students' comments, researchers looked into the effects of dark mode on HCI in e-learning sites. The findings indicate that students have a clear preference for dark mode: 79.7% of survey participants preferred dark mode on their phones, and 61.7% said they would be interested in seeing this feature added to e-learning websites., Comment: none
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- 2024
4. GPTKB: Building Very Large Knowledge Bases from Language Models
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Hu, Yujia, Ghosh, Shrestha, Nguyen, Tuan-Phong, and Razniewski, Simon
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Computer Science - Computation and Language ,Computer Science - Artificial Intelligence ,Computer Science - Databases - Abstract
General-domain knowledge bases (KB), in particular the "big three" -- Wikidata, Yago and DBpedia -- are the backbone of many intelligent applications. While these three have seen steady development, comprehensive KB construction at large has seen few fresh attempts. In this work, we propose to build a large general-domain KB entirely from a large language model (LLM). We demonstrate the feasibility of large-scale KB construction from LLMs, while highlighting specific challenges arising around entity recognition, entity and property canonicalization, and taxonomy construction. As a prototype, we use GPT-4o-mini to construct GPTKB, which contains 105 million triples for more than 2.9 million entities, at a cost 100x less than previous KBC projects. Our work is a landmark for two fields: For NLP, for the first time, it provides \textit{constructive} insights into the knowledge (or beliefs) of LLMs. For the Semantic Web, it shows novel ways forward for the long-standing challenge of general-domain KB construction. GPTKB is accessible at http://gptkb.org., Comment: 11 pages, 4 tables
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- 2024
5. Rubin ToO 2024: Envisioning the Vera C. Rubin Observatory LSST Target of Opportunity program
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Andreoni, Igor, Margutti, Raffaella, Banovetz, John, Greenstreet, Sarah, Hebert, Claire-Alice, Lister, Tim, Palmese, Antonella, Piranomonte, Silvia, Smartt, S. J., Smith, Graham P., Stein, Robert, Ahumada, Tomas, Anand, Shreya, Auchettl, Katie, Bannister, Michele T., Bellm, Eric C., Bloom, Joshua S., Bolin, Bryce T., Bom, Clecio R., Brethauer, Daniel, Brucker, Melissa J., Buckley, David A. H., Chandra, Poonam, Chornock, Ryan, Christensen, Eric, Cooke, Jeff, Corsi, Alessandra, Coughlin, Michael W., Cuevas-Otahola, Bolivia, Filippo, D'Ammando, Dai, Biwei, Dhawan, S., Filippenko, Alexei V., Foley, Ryan J., Franckowiak, Anna, Gomboc, Andreja, Gompertz, Benjamin P., Guy, Leanne P., Hazra, Nandini, Hernandez, Christopher, Hosseinzadeh, Griffin, Hussaini, Maryam, Ibrahimzade, Dina, Izzo, Luca, Jones, R. Lynne, Kang, Yijung, Kasliwal, Mansi M., Knight, Matthew, Kunnumkai, Keerthi, Lamb, Gavin P, LeBaron, Natalie, Lejoly, Cassandra, Levan, Andrew J., MacBride, Sean, Mallia, Franco, Malz, Alex I., Miller, Adam A., Mora, J. C., Narayan, Gautham, J., Nayana A., Nicholl, Matt, Nichols, Tiffany, Oates, S. R., Panayada, Akshay, Ragosta, Fabio, Ribeiro, Tiago, Ryczanowski, Dan, Sarin, Nikhil, Schwamb, Megan E., Sears, Huei, Seligman, Darryl Z., Sharma, Ritwik, Shrestha, Manisha, Simran, Stroh, Michael C., Terreran, Giacomo, Thakur, Aishwarya Linesh, Trivedi, Aum, Tyson, J. Anthony, Utsumi, Yousuke, Verma, Aprajita, Villar, V. Ashley, Volk, Kathryn, Vyas, Meet J., Wasserman, Amanda R., Wheeler, J. Craig, Yoachim, Peter, Zegarelli, Angela, and Bianco, Federica
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Astrophysics - Instrumentation and Methods for Astrophysics ,Astrophysics - High Energy Astrophysical Phenomena ,Astrophysics - Solar and Stellar Astrophysics - Abstract
The Legacy Survey of Space and Time (LSST) at Vera C. Rubin Observatory is planned to begin in the Fall of 2025. The LSST survey cadence has been designed via a community-driven process regulated by the Survey Cadence Optimization Committee (SCOC), which recommended up to 3% of the observing time to carry out Target of Opportunity (ToO) observations. Experts from the scientific community, Rubin Observatory personnel, and members of the SCOC were brought together to deliver a recommendation for the implementation of the ToO program during a workshop held in March 2024. Four main science cases were identified: gravitational wave multi-messenger astronomy, high energy neutrinos, Galactic supernovae, and small potentially hazardous asteroids possible impactors. Additional science cases were identified and briefly addressed in the documents, including lensed or poorly localized gamma-ray bursts and twilight discoveries. Trigger prioritization, automated response, and detailed strategies were discussed for each science case. This document represents the outcome of the Rubin ToO 2024 workshop, with additional contributions from members of the Rubin Science Collaborations. The implementation of the selection criteria and strategies presented in this document has been endorsed in the SCOC Phase 3 Recommendations document (PSTN-056). Although the ToO program is still to be finalized, this document serves as a baseline plan for ToO observations with the Rubin Observatory.
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- 2024
6. Content-Style Learning from Unaligned Domains: Identifiability under Unknown Latent Dimensions
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Shrestha, Sagar and Fu, Xiao
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Computer Science - Machine Learning ,Computer Science - Artificial Intelligence - Abstract
Understanding identifiability of latent content and style variables from unaligned multi-domain data is essential for tasks such as domain translation and data generation. Existing works on content-style identification were often developed under somewhat stringent conditions, e.g., that all latent components are mutually independent and that the dimensions of the content and style variables are known. We introduce a new analytical framework via cross-domain \textit{latent distribution matching} (LDM), which establishes content-style identifiability under substantially more relaxed conditions. Specifically, we show that restrictive assumptions such as component-wise independence of the latent variables can be removed. Most notably, we prove that prior knowledge of the content and style dimensions is not necessary for ensuring identifiability, if sparsity constraints are properly imposed onto the learned latent representations. Bypassing the knowledge of the exact latent dimension has been a longstanding aspiration in unsupervised representation learning -- our analysis is the first to underpin its theoretical and practical viability. On the implementation side, we recast the LDM formulation into a regularized multi-domain GAN loss with coupled latent variables. We show that the reformulation is equivalent to LDM under mild conditions -- yet requiring considerably less computational resource. Experiments corroborate with our theoretical claims.
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- 2024
7. Asymmetries and Circumstellar Interaction in the Type II SN 2024bch
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Andrews, Jennifer E., Shrestha, Manisha, Bostroem, K. Azalee, Dong, Yize, Pearson, Jeniveve, Fausnaugh, M. M., Sand, David J., Valenti, S., Ravi, Aravind P., Hoang, Emily, Hosseinzadeh, Griffin, Ilyin, Ilya, Janzen, Daryl, Lundquist, M. J., Meza, Nicolaz, Smith, Nathan, Jha, Saurabh W., Andrews, Moira, Farah, Joseph, Gonzalez, Estefania Padilla, Howell, D. Andrew, McCully, Curtis, Newsome, Megan, Pellegrino, Craig, Terreran, Giacomo, Wiggins, Patrick, Hsu, Brian, Christy, Collin T., Wang, Xiofeng, Liu, Jialian, and Chen, Liyang
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Astrophysics - High Energy Astrophysical Phenomena ,Astrophysics - Solar and Stellar Astrophysics - Abstract
We present a comprehensive multi-epoch photometric and spectroscopic study of SN 2024bch, a nearby (19.9 Mpc) Type II supernova (SN) with prominent early high ionization emission lines. Optical spectra from 2.9 days after the estimated explosion reveal narrow lines of H I, He II, C IV, and N IV that disappear by day 6. High cadence photometry from the ground and TESS show that the SN brightened quickly and reached a peak M$_V \sim$ $-$17.8 mag within a week of explosion, and late-time photometry suggests a $^{56}$Ni mass of 0.050 M$_{\odot}$. High-resolution spectra from day 8 and 43 trace the unshocked circumstellar medium (CSM) and indicate a wind velocity of 30--40 km s$^{-1}$, a value consistent with a red supergiant (RSG) progenitor. Comparisons between models and the early spectra suggest a pre-SN mass-loss rate of $\dot{M} \sim 10^{-3}-10^{-2}\ M_\odot\ \mathrm{yr}^{-1}$, which is too high to be explained by quiescent mass loss from RSGs, but is consistent with some recent measurements of similar SNe. Persistent blueshifted H I and [O I] emission lines seen in the optical and NIR spectra could be produced by asymmetries in the SN ejecta, while the multi-component H$\alpha$ may indicate continued interaction with an asymmetric CSM well into the nebular phase. SN 2024bch provides another clue to the complex environments and mass-loss histories around massive stars., Comment: Submitted to ApJ
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- 2024
8. Luminous Type II Short-Plateau SN 2023ufx: Asymmetric Explosion of a Partially-Stripped Massive Progenitor
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Ravi, Aravind P., Valenti, Stefano, Dong, Yize, Hiramatsu, Daichi, Barmentloo, Stan, Jerkstrand, Anders, Bostroem, K. Azalee, Pearson, Jeniveve, Shrestha, Manisha, Andrews, Jennifer E., Sand, David J., Hosseinzadeh, Griffin, Lundquist, Michael, Hoang, Emily, Mehta, Darshana, Retamal, Nicolas Meza, Martas, Aidan, Jha, Saurabh W., Janzen, Daryl, Subrayan, Bhagya, Howell, D. Andrew, McCully, Curtis, Farah, Joseph, Newsome, Megan, Gonzalez, Estefania Padilla, Terreran, Giacomo, Andrews, Moira, Filippenko, Alexei V., Brink, Thomas G., Zheng, Weikang, Yang, Yi, Vinko, Jozsef, Wheeler, J. Craig, Smith, Nathan, Rho, Jeonghee, Konyves-Toth, Reka, and Gutierrez, Claudia P.
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Astrophysics - High Energy Astrophysical Phenomena ,Astrophysics - Solar and Stellar Astrophysics - Abstract
We present supernova (SN) 2023ufx, a unique Type IIP SN with the shortest known plateau duration ($t_\mathrm{PT}$ $\sim$47 days), a luminous V-band peak ($M_{V}$ = $-$18.42 $\pm$ 0.08 mag), and a rapid early decline rate ($s1$ = 3.47 $\pm$ 0.09 mag (50 days)$^{-1}$). By comparing observed photometry to a hydrodynamic MESA+STELLA model grid, we constrain the progenitor to be a massive red supergiant with M$_\mathrm{ZAMS}$ $\simeq$19 - 25 M$_{\odot}$. Independent comparisons with nebular spectral models also suggest an initial He-core mass of $\sim$6 M$_{\odot}$, and thus a massive progenitor. For a Type IIP, SN 2023ufx produced an unusually high amount of nickel ($^{56}$Ni) $\sim$0.14 $\pm$ 0.02 M$_{\odot}$, during the explosion. We find that the short plateau duration in SN 2023ufx can be explained with the presence of a small hydrogen envelope (M$_\mathrm{H_\mathrm{env}}$ $\simeq$1.2 M$_{\odot}$), suggesting partial stripping of the progenitor. About $\simeq$0.09 M$_{\odot}$ of CSM through mass loss from late-time stellar evolution of the progenitor is needed to fit the early time ($\lesssim$10 days) pseudo-bolometric light curve. Nebular line diagnostics of broad and multi-peak components of [O I] $\lambda\lambda$6300, 6364, H$\alpha$, and [Ca II] $\lambda \lambda$7291, 7323 suggest that the explosion of SN 2023ufx could be inherently asymmetric, preferentially ejecting material along our line-of-sight., Comment: Submitted to ApJ, 30 pages, 19 figures
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- 2024
9. Improving Multimodal Large Language Models Using Continual Learning
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Srivastava, Shikhar, Harun, Md Yousuf, Shrestha, Robik, and Kanan, Christopher
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Computer Science - Computation and Language ,Computer Science - Computer Vision and Pattern Recognition ,Computer Science - Machine Learning - Abstract
Generative large language models (LLMs) exhibit impressive capabilities, which can be further augmented by integrating a pre-trained vision model into the original LLM to create a multimodal LLM (MLLM). However, this integration often significantly decreases performance on natural language understanding and generation tasks, compared to the original LLM. This study investigates this issue using the LLaVA MLLM, treating the integration as a continual learning problem. We evaluate five continual learning methods to mitigate forgetting and identify a technique that enhances visual understanding while minimizing linguistic performance loss. Our approach reduces linguistic performance degradation by up to 15\% over the LLaVA recipe, while maintaining high multimodal accuracy. We also demonstrate the robustness of our method through continual learning on a sequence of vision-language tasks, effectively preserving linguistic skills while acquiring new multimodal capabilities., Comment: NeurIPS 2024 Workshop on Scalable Continual Learning for Lifelong Foundation Models
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- 2024
10. Towards Automated Penetration Testing: Introducing LLM Benchmark, Analysis, and Improvements
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Isozaki, Isamu, Shrestha, Manil, Console, Rick, and Kim, Edward
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Computer Science - Cryptography and Security ,Computer Science - Artificial Intelligence - Abstract
Hacking poses a significant threat to cybersecurity, inflicting billions of dollars in damages annually. To mitigate these risks, ethical hacking, or penetration testing, is employed to identify vulnerabilities in systems and networks. Recent advancements in large language models (LLMs) have shown potential across various domains, including cybersecurity. However, there is currently no comprehensive, open, end-to-end automated penetration testing benchmark to drive progress and evaluate the capabilities of these models in security contexts. This paper introduces a novel open benchmark for LLM-based automated penetration testing, addressing this critical gap. We first evaluate the performance of LLMs, including GPT-4o and Llama 3.1-405B, using the state-of-the-art PentestGPT tool. Our findings reveal that while Llama 3.1 demonstrates an edge over GPT-4o, both models currently fall short of performing fully automated, end-to-end penetration testing. Next, we advance the state-of-the-art and present ablation studies that provide insights into improving the PentestGPT tool. Our research illuminates the challenges LLMs face in each aspect of Pentesting, e.g. enumeration, exploitation, and privilege escalation. This work contributes to the growing body of knowledge on AI-assisted cybersecurity and lays the foundation for future research in automated penetration testing using large language models., Comment: Main Paper 1-9 pages, Supplementary Materials: 10-17, 13 figures
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- 2024
11. Automated Segmentation and Analysis of Cone Photoreceptors in Multimodal Adaptive Optics Imaging
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Shrestha, Prajol, Kulyabin, Mikhail, Sindel, Aline, Pedersen, Hilde R., Gilson, Stuart, Baraas, Rigmor, and Maier, Andreas
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Electrical Engineering and Systems Science - Image and Video Processing ,Computer Science - Computer Vision and Pattern Recognition - Abstract
Accurate detection and segmentation of cone cells in the retina are essential for diagnosing and managing retinal diseases. In this study, we used advanced imaging techniques, including confocal and non-confocal split detector images from adaptive optics scanning light ophthalmoscopy (AOSLO), to analyze photoreceptors for improved accuracy. Precise segmentation is crucial for understanding each cone cell's shape, area, and distribution. It helps to estimate the surrounding areas occupied by rods, which allows the calculation of the density of cone photoreceptors in the area of interest. In turn, density is critical for evaluating overall retinal health and functionality. We explored two U-Net-based segmentation models: StarDist for confocal and Cellpose for calculated modalities. Analyzing cone cells in images from two modalities and achieving consistent results demonstrates the study's reliability and potential for clinical application.
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- 2024
12. SDI-Paste: Synthetic Dynamic Instance Copy-Paste for Video Instance Segmentation
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Shrestha, Sahir, Li, Weihao, Zhu, Gao, and Barnes, Nick
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Computer Science - Computer Vision and Pattern Recognition - Abstract
Data augmentation methods such as Copy-Paste have been studied as effective ways to expand training datasets while incurring minimal costs. While such methods have been extensively implemented for image level tasks, we found no scalable implementation of Copy-Paste built specifically for video tasks. In this paper, we leverage the recent growth in video fidelity of generative models to explore effective ways of incorporating synthetically generated objects into existing video datasets to artificially expand object instance pools. We first procure synthetic video sequences featuring objects that morph dynamically with time. Our carefully devised pipeline automatically segments then copy-pastes these dynamic instances across the frames of any target background video sequence. We name our video data augmentation pipeline Synthetic Dynamic Instance Copy-Paste, and test it on the complex task of Video Instance Segmentation which combines detection, segmentation and tracking of object instances across a video sequence. Extensive experiments on the popular Youtube-VIS 2021 dataset using two separate popular networks as baselines achieve strong gains of +2.9 AP (6.5%) and +2.1 AP (4.9%). We make our code and models publicly available.
- Published
- 2024
13. First-principles study of the electronic structure, Z2 invariant and quantum oscillation in the kagome material CsV3Sb5
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Bhandari, Shalika R., Zeeshan, Mohd, Gusain, Vivek, Shrestha, Keshav, and Rai, D. P.
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Condensed Matter - Strongly Correlated Electrons - Abstract
This work presents a detailed study of the electronic structure, phonon dispersion, Z2 invariant calculation, and Fermi surface of the newly discovered kagome superconductor CsV3Sb5, using density functional theory (DFT). The phonon dispersion in the pristine state reveals two negative modes at the M and L points of the Brillouin zone, indicating lattice instability. CsV3Sb5 transitions into a structurally stable 2x2x1 charge density wave (CDW) phase, confirmed by positive phonon modes. The electronic band structure shows several Dirac points near the Fermi level, with a narrow gap opening due to spin-orbit coupling (SOC), though the effect of SOC on other bands is minimal. In the pristine phase, this material exhibits a quasi-2D cylindrical Fermi surface, which undergoes reconstruction in the CDW phase. We calculated quantum oscillation frequencies using Onsager's relation, finding good agreement with experimental results in the CDW phase. To explore the topological properties of CsV3Sb5, we computed the Z2 invariant in both pristine and CDW phases, resulting in a value of (u0; u1u2u3) = (1; 000), suggesting the strong topological nature of this material. Our detailed analysis of phonon dispersion, electronic bands, Fermi surface mapping, and Z2 invariant provides insights into the topological properties, CDW order, and unconventional superconductivity in AV3Sb5 (A = K, Rb, and Cs)., Comment: To be published in APL Quantum
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- 2024
14. Spectropolarimetry of SN 2023ixf reveals both circumstellar material and helium core to be aspherical
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Shrestha, Manisha, DeSoto, Sabrina, Sand, David J., Williams, G. Grant, Hoffman, Jennifer L., Smith, Nathan, Smith, Paul S., Milne, Peter, McCall, Callum, Maund, Justyn R., Steele, Iain A, Wiersema, Klaas, Andrews, Jennifer E., Bilinski, Christopher, Anche, Ramya M., Bostroem, K. Azalee, Hosseinzadeh, Griffin, Pearson, Jeniveve, Leonard, Douglas C., Hsu, Brian, Dong, Yize, Hoang, Emily, Janzen, Daryl, Jencson, Jacob E., Jha, Saurabh W., Lundquist, M. J., Mehta, Darshana, Retamal, Nicolas Meza, Valenti, Stefano, Farah, Joseph, Howell, D. Andrew, McCully, Curtis, Newsome, Megan, Gonzalez, Estefania Padilla, Pellegrino, Craig, and Terreran, Giacomo
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Astrophysics - High Energy Astrophysical Phenomena ,Astrophysics - Solar and Stellar Astrophysics - Abstract
We present multi-epoch optical spectropolarimetric and imaging polarimetric observations of the nearby Type II supernova (SN) 2023ixf discovered in M101 at a distance of 6.85 Mpc. The first imaging polarimetric observations were taken +2.33 days (60085.08 MJD) after the explosion, while the last imaging polarimetric data points (+73.19 and +76.19 days) were acquired after the fall from the light curve plateau. At +2.33 days there is strong evidence of circumstellar material (CSM) interaction in the spectra and the light curve. A significant level of polarization $P_r = 0.88\pm 0.06 \% $ seen during this phase indicates that this CSM is aspherical. We find that the polarization evolves with time toward the interstellar polarization level ($0.35\%$) during the photospheric phase, which suggests that the recombination photosphere is spherically symmetric. There is a jump in polarization ($P_r =0.65 \pm 0.08 \% $) at +73.19 days when the light curve falls from the plateau. This is a phase where polarimetric data is sensitive to non-spherical inner ejecta or a decrease in optical depth into the single scattering regime. We also present spectropolarimetric data that reveal line (de)polarization during most of the observed epochs. In addition, at +14.50 days we see an "inverse P Cygn" profile in the H and He line polarization, which clearly indicates the presence of asymmetrically distributed material overlying the photosphere. The overall temporal evolution of polarization is typical for Type II SNe, but the high level of polarization during the rising phase has only been observed in SN 2023ixf., Comment: 14 pages, 7 figures, submitted to ApJL, comments welcome
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- 2024
15. RayEmb: Arbitrary Landmark Detection in X-Ray Images Using Ray Embedding Subspace
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Shrestha, Pragyan, Xie, Chun, Yoshii, Yuichi, and Kitahara, Itaru
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Computer Science - Computer Vision and Pattern Recognition - Abstract
Intra-operative 2D-3D registration of X-ray images with pre-operatively acquired CT scans is a crucial procedure in orthopedic surgeries. Anatomical landmarks pre-annotated in the CT volume can be detected in X-ray images to establish 2D-3D correspondences, which are then utilized for registration. However, registration often fails in certain view angles due to poor landmark visibility. We propose a novel method to address this issue by detecting arbitrary landmark points in X-ray images. Our approach represents 3D points as distinct subspaces, formed by feature vectors (referred to as ray embeddings) corresponding to intersecting rays. Establishing 2D-3D correspondences then becomes a task of finding ray embeddings that are close to a given subspace, essentially performing an intersection test. Unlike conventional methods for landmark estimation, our approach eliminates the need for manually annotating fixed landmarks. We trained our model using the synthetic images generated from CTPelvic1K CLINIC dataset, which contains 103 CT volumes, and evaluated it on the DeepFluoro dataset, comprising real X-ray images. Experimental results demonstrate the superiority of our method over conventional methods. The code is available at https://github.com/Pragyanstha/rayemb., Comment: Accepted as an oral presentation at ACCV 2024
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- 2024
16. An Optimized H5 Hysteresis Current Control with Clamped Diodes in Transformer-less Grid-PV Inverter
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Phuyal, Sushil, Shrestha, Shashwot, Sharma, Swodesh, Subedi, Rachana, Panjiyar, Anil Kumar, and Gautam, Mukesh
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Electrical Engineering and Systems Science - Systems and Control - Abstract
With the rise of renewable energy penetration in the grid, photovoltaic (PV) panels are connected to the grid via inverters to supply solar energy. Transformer-less grid-tied PV inverters are gaining popularity because of their improved efficiency, reduced size, and lower costs. However, they can induce a path for leakage currents between the PV and the grid part due to the absence of galvanic isolation between them. This leads to serious electromagnetic interference, loss in efficiency and safety concerns. The leakage current is primarily influenced by the nature of the common mode voltage (CMV), which is determined by the switching techniques of the inverter. In this paper, a novel inverter topology of Hysteresis Controlled H5 with Two Clamping Diodes (HCH5-D2) has been derived. The HCH5-D2 topology helps to decouple the AC part (Grid) and DC part (PV) during the freewheeling to make the CMV constant and in turn, reduces the leakage current. Also, the additional diodes help to reduce the voltage spikes generated during the freewheeling period and maintain the CMV at a constant value. Finally, a 2.2kW grid-connected single-phase HCH5-D2 PV inverter system's MATLAB simulation has been presented with better results when compared with a traditional H4 inverter.
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- 2024
17. LightSC: The Making of a Usable Security Classification Tool for DevSecOps
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Shrestha, Manish, Johansen, Christian, and Johansen, Johanna
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Computer Science - Cryptography and Security ,Computer Science - Human-Computer Interaction ,Computer Science - Software Engineering - Abstract
DevSecOps, as the extension of DevOps with security training and tools, has become a popular way of developing modern software, especially in the Internet of Things arena, due to its focus on rapid development, with short release cycles, involving the user/client very closely. Security classification methods, on the other hand, are heavy and slow processes that require high expertise in security, the same as in other similar areas such as risk analysis or certification. As such, security classification methods are hardly compatible with the DevSecOps culture, which to the contrary, has moved away from the traditional style of penetration testing done only when the software product is in the final stages or already deployed. In this work, we first propose five principles for a security classification to be \emph{DevOps-ready}, two of which will be the focus for the rest of the paper, namely to be tool-based and easy to use for non-security experts, such as ordinary developers or system architects. We then exemplify how one can make a security classification methodology DevOps-ready. We do this through an interaction design process, where we create and evaluate the usability of a tool implementing the chosen methodology. Since such work seems to be new within the usable security community, and even more so in the software development (DevOps) community, we extract from our process a general, three-steps `recipe' that others can follow when making their own security methodologies DevOps-ready. The tool that we build is in itself a contribution of this process, as it can be independently used, extended, and/or integrated by developer teams into their DevSecOps tool-chains. Our tool is perceived (by the test subjects) as most useful in the design phase, but also during the testing phase where the security class would be one of the metrics used to evaluate the quality of their software., Comment: 29 pages of which 7 are appendix with figures
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- 2024
18. Sub-actions for geodesic flows on locally CAT(-1) spaces
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Constantine, David, Shrestha, Elvin, and Wu, Yandi
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Mathematics - Dynamical Systems ,Mathematics - Metric Geometry ,37D40 - Abstract
We extend a result of Lopes and Thieullen on sub-actions for smooth Anosov flows to the setting of geodesic flow on locally CAT(-1) spaces. This allows us to use arguments originally due to Croke and Dairbekov to prove a volume rigidity theorem for some interesting locally CAT(-1) spaces, including quotients of Fuchsian buildings and surface amalgams., Comment: 56 pages, 6 figures
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- 2024
19. Identifiable Shared Component Analysis of Unpaired Multimodal Mixtures
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Timilsina, Subash, Shrestha, Sagar, and Fu, Xiao
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Computer Science - Machine Learning ,Computer Science - Artificial Intelligence ,Statistics - Machine Learning - Abstract
A core task in multi-modal learning is to integrate information from multiple feature spaces (e.g., text and audio), offering modality-invariant essential representations of data. Recent research showed that, classical tools such as {\it canonical correlation analysis} (CCA) provably identify the shared components up to minor ambiguities, when samples in each modality are generated from a linear mixture of shared and private components. Such identifiability results were obtained under the condition that the cross-modality samples are aligned/paired according to their shared information. This work takes a step further, investigating shared component identifiability from multi-modal linear mixtures where cross-modality samples are unaligned. A distribution divergence minimization-based loss is proposed, under which a suite of sufficient conditions ensuring identifiability of the shared components are derived. Our conditions are based on cross-modality distribution discrepancy characterization and density-preserving transform removal, which are much milder than existing studies relying on independent component analysis. More relaxed conditions are also provided via adding reasonable structural constraints, motivated by available side information in various applications. The identifiability claims are thoroughly validated using synthetic and real-world data.
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- 2024
20. Secure Multiparty Generative AI
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Shrestha, Manil, Ravichandran, Yashodha, and Kim, Edward
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Computer Science - Cryptography and Security ,Computer Science - Artificial Intelligence - Abstract
As usage of generative AI tools skyrockets, the amount of sensitive information being exposed to these models and centralized model providers is alarming. For example, confidential source code from Samsung suffered a data leak as the text prompt to ChatGPT encountered data leakage. An increasing number of companies are restricting the use of LLMs (Apple, Verizon, JPMorgan Chase, etc.) due to data leakage or confidentiality issues. Also, an increasing number of centralized generative model providers are restricting, filtering, aligning, or censoring what can be used. Midjourney and RunwayML, two of the major image generation platforms, restrict the prompts to their system via prompt filtering. Certain political figures are restricted from image generation, as well as words associated with women's health care, rights, and abortion. In our research, we present a secure and private methodology for generative artificial intelligence that does not expose sensitive data or models to third-party AI providers. Our work modifies the key building block of modern generative AI algorithms, e.g. the transformer, and introduces confidential and verifiable multiparty computations in a decentralized network to maintain the 1) privacy of the user input and obfuscation to the output of the model, and 2) introduce privacy to the model itself. Additionally, the sharding process reduces the computational burden on any one node, enabling the distribution of resources of large generative AI processes across multiple, smaller nodes. We show that as long as there exists one honest node in the decentralized computation, security is maintained. We also show that the inference process will still succeed if only a majority of the nodes in the computation are successful. Thus, our method offers both secure and verifiable computation in a decentralized network.
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- 2024
21. Improving the Accessibility of Dating Websites for Individuals with Visual Impairments
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Shrestha, Gyanendra and Vadlamani, Soumya Tejaswi
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Computer Science - Human-Computer Interaction ,Computer Science - Machine Learning - Abstract
People now frequently meet and develop relationships through online dating. Yet, due to their limited accessibility, utilizing dating services can be difficult and irritating for people with visual impairments. The significance of the research issue can be attributed to the fact that dating websites are becoming more and more common and have a significant impact on how people establish romantic connections. It can be challenging for people with visual impairments to use dating services and develop lasting relationships because many of them are not created with their requirements in mind. We can encourage people with visual impairments to participate more completely in online dating and possibly enhance the success of their romantic relationships by making dating websites more accessible. There is some existing implementation that can automatically recognize the facial expression, age, gender, presence of child(ren) and other common objects from a profile photo in a dating platform. The goal of this project is incorporate additional features (presence of any common pets, indoor vs. outdoor image) to further enhance the capability of existing system and come up with test viable solutions to accessibility issues that people with visual impairments face when using dating websites.
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- 2024
22. A Diagonal Structured State Space Model on Loihi 2 for Efficient Streaming Sequence Processing
- Author
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Meyer, Svea Marie, Weidel, Philipp, Plank, Philipp, Campos-Macias, Leobardo, Shrestha, Sumit Bam, Stratmann, Philipp, and Richter, Mathis
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Computer Science - Machine Learning ,Computer Science - Artificial Intelligence ,Computer Science - Emerging Technologies ,Computer Science - Neural and Evolutionary Computing - Abstract
Deep State-Space Models (SSM) demonstrate state-of-the art performance on long-range sequence modeling tasks. While the recurrent structure of SSMs can be efficiently implemented as a convolution or as a parallel scan during training, recurrent token-by-token processing cannot currently be implemented efficiently on GPUs. Here, we demonstrate efficient token-by-token inference of the SSM S4D on Intel's Loihi 2 state-of-the-art neuromorphic processor. We compare this first ever neuromorphic-hardware implementation of an SSM on sMNIST, psMNIST, and sCIFAR to a recurrent and a convolutional implementation of S4D on Jetson Orin Nano (Jetson). While we find Jetson to perform better in an offline sample-by-sample based batched processing mode, Loihi 2 outperforms during token-by-token based processing, where it consumes 1000 times less energy with a 75 times lower latency and a 75 times higher throughput compared to the recurrent implementation of S4D on Jetson. This opens up new avenues towards efficient real-time streaming applications of SSMs., Comment: 6 pages, 2 figures
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- 2024
23. The Effect of Education in Prompt Engineering: Evidence from Journalists
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Bashardoust, Amirsiavosh, Feng, Yuanjun, Geissler, Dominique, Feuerriegel, Stefan, and Shrestha, Yash Raj
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Computer Science - Human-Computer Interaction - Abstract
Large language models (LLMs) are increasingly used in daily work. In this paper, we analyze whether training in prompt engineering can improve the interactions of users with LLMs. For this, we conducted a field experiment where we asked journalists to write short texts before and after training in prompt engineering. We then analyzed the effect of training on three dimensions: (1) the user experience of journalists when interacting with LLMs, (2) the accuracy of the texts (assessed by a domain expert), and (3) the reader perception, such as clarity, engagement, and other text quality dimensions (assessed by non-expert readers). Our results show: (1) Our training improved the perceived expertise of journalists but also decreased the perceived helpfulness of LLM use. (2) The effect on accuracy varied by the difficulty of the task. (3) There is a mixed impact of training on reader perception across different text quality dimensions.
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- 2024
24. Measurement of the nucleon spin structure functions for $0.01<Q^2<1$~GeV$^2$ using CLAS
- Author
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Deur, A., Kuhn, S. E., Ripani, M., Zheng, X., Acar, A. G., Achenbach, P., Adhikari, K. P., Alvarado, J. S., Amaryan, M. J., Armstrong, W. R., Atac, H., Avakian, H., Baashen, L., Baltzell, N. A., Barion, L., Bashkanov, M., Battaglieri, M., Benkel, B., Benmokhtar, F., Bianconi, A., Biselli, A. S., Booth, W. A., ossu, F. B, Bosted, P., Boiarinov, S., Brinkmann, K. Th., Briscoe, W. J., Bueltmann, S., Burkert, V. D., Carman, D. S., Chatagnon, P., Chen, J. P., Ciullo, G., Cole, P. L., Contalbrigo, M., Crede, V., D'Angelo, A., Dashyan, N., De Vita, R., Defurne, M., Diehl, S., Djalali, C., Drozdov, V. A., Dupre, R., Egiyan, H., Alaoui, A. El, Fassi, L. El, Elouadrhiri, L., Eugenio, P., Faggert, J. C., Fegan, S., Fersch, R., Filippi, A., Gates, K., Gavalian, G., Gilfoyle, G. P., Gothe, R. W., Guo, L., Hakobyan, H., Hattawy, M., Hauenstein, F., Heddle, D., Hobart, A., Holtrop, M., Ireland, D. G., Isupov, E. L., Jiang, H., Jo, H. S., Joosten, S., Kang, H., Keith, C., Khandaker, M., Kim, W., Klein, F. J., Klimenko, V., Konczykowski, P., Kovacs, K., Kripko, A., Kubarovsky, V., Lanza, L., Lee, S., Lenisa, P., Li, X., Long, E., MacGregor, I. J. D., Marchand, D., Mascagna, V., Matamoros, D., McKinnon, B., Meekins, D., Migliorati, S., Mineeva, T., Mirazita, M., Mokeev, V., Munoz-Camacho, C., Nadel-Turonski, P., Nagorna, T., Neupane, K., Niccolai, S., Osipenko, M., Ostrovidov, A. I., Pandey, P., Paolone, M., Pappalardo, L. L., Paremuzyan, R., Pasyuk, E., Paul, S. J., Phelps, W., Phillips, S. K., Pierce, J., Pilleux, N., Pokhrel, M., Price, J. W., Prok, Y., Radic, A., Reed, T., Richards, J., Rosner, G., Rossi, P., Rusova, A. A., Salgado, C., Schmidt, A., Schumacher, R. A., Sharabian, Y. G., Shirokov, E. V., Shrestha, U., Sirca, S., Sparveris, N., Spreafico, M., Stepanyan, S., Strakovsky, I. I., Strauch, S., Sulkosky, V., Tan, J. A., Tenorio, M., Trotta, N., Tyson, R., Ungaro, M., Upton, D. W., Vallarino, S., Venturelli, L., Voskanyan, H., Voutier, E., Watts, D. P., Wei, X., Wood, M. H., Zachariou, N., Zhang, J., and Zurek, M.
- Subjects
Nuclear Experiment - Abstract
The spin structure functions of the proton and the deuteron were measured during the EG4 experiment at Jefferson Lab in 2006. Data were collected for longitudinally polarized electron scattering off longitudinally polarized NH$_3$ and ND$_3$ targets, for $Q^2$ values as small as 0.012 and 0.02 GeV$^2$, respectively, using the CEBAF Large Acceptance Spectrometer (CLAS). This is the archival paper of the EG4 experiment that summaries the previously reported results of the polarized structure functions $g_1$, $A_1F_1$, and their moments $\overline \Gamma_1$, $\overline \gamma_0$, and $\overline I_{TT}$, for both the proton and the deuteron. In addition, we report on new results on the neutron $g_1$ extracted by combining proton and deuteron data and correcting for Fermi smearing, and on the neutron moments $\overline \Gamma_1$, $\overline \gamma_0$, and $\overline I_{TT}$ formed directly from those of the proton and the deuteron. Our data are in good agreement with the Gerasimov-Drell-Hearn sum rule for the proton, deuteron, and neutron. Furthermore, the isovector combination was formed for $g_1$ and the Bjorken integral $\overline \Gamma_1^{p-n}$, and compared to available theoretical predictions. All of our results provide for the first time extensive tests of spin observable predictions from chiral effective field theory ($\chi$EFT) in a $Q^2$ range commensurate with the pion mass. They motivate further improvement in $\chi$EFT calculations from other approaches such as the lattice gauge method., Comment: 33 pages. 26 figures. Data table provided in supplementary material (30 pages)
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- 2024
25. Design and development of desktop braille printing machine at Fablab Nepal
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Ghimire, Daya Bandhu and Shrestha, Pallab
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Computer Science - Human-Computer Interaction ,Computer Science - Computers and Society - Abstract
The development of a desktop Braille printing machine aims to create an affordable, user-friendly device for visually impaired users. This document outlines the entire process, from research and requirement analysis to distribution and support, leveraging the content and guidelines from the GitHub repository,https://github.com/fablabnepal1/Desktop-Braille-Printing-Machine.
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- 2024
26. On the Relationship between Truth and Political Bias in Language Models
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Fulay, Suyash, Brannon, William, Mohanty, Shrestha, Overney, Cassandra, Poole-Dayan, Elinor, Roy, Deb, and Kabbara, Jad
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Computer Science - Computation and Language ,Computer Science - Artificial Intelligence - Abstract
Language model alignment research often attempts to ensure that models are not only helpful and harmless, but also truthful and unbiased. However, optimizing these objectives simultaneously can obscure how improving one aspect might impact the others. In this work, we focus on analyzing the relationship between two concepts essential in both language model alignment and political science: truthfulness and political bias. We train reward models on various popular truthfulness datasets and subsequently evaluate their political bias. Our findings reveal that optimizing reward models for truthfulness on these datasets tends to result in a left-leaning political bias. We also find that existing open-source reward models (i.e., those trained on standard human preference datasets) already show a similar bias and that the bias is larger for larger models. These results raise important questions about the datasets used to represent truthfulness, potential limitations of aligning models to be both truthful and politically unbiased, and what language models capture about the relationship between truth and politics., Comment: EMNLP 2024
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- 2024
27. Optimal solutions employing an algebraic Variational Multiscale approach Part I: Steady Linear Problems
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Shrestha, Suyash, Gerritsma, Marc, Rubio, Gonzalo, Hulshoff, Steven, and Ferrer, Esteban
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Mathematics - Numerical Analysis ,Mathematical Physics - Abstract
This work extends our previous study from S. Shrestha et al. (2024) by introducing a new abstract framework for Variational Multiscale (VMS) methods at the discrete level. We introduce the concept of what we define as the optimal projector and present an approach where the infinite-dimensional unresolved scales are approximated in a finite-dimensional subspace using the numerically computed Fine-Scale Greens' function of the underlying symmetric problem. The proposed approach involves solving the VMS problem on two separate meshes: a coarse mesh for the full PDE and a fine mesh for the symmetric part of the continuous differential operator. We consider the 1D and 2D steady advection-diffusion problems in both direct and mixed formulations as the test cases in this paper. Moreover, we demonstrate the working of this method using the Mimetic Spectral Element Method (MSEM), however, it may be applied to other Finite/Spectral Element or Isogeometric frameworks. Furthermore, we propose that VMS should not be viewed as a stabilisation technique; instead, the base scheme should be inherently stable, with VMS enhancing the solution quality by supplementing the base scheme.
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- 2024
28. CAR-MFL: Cross-Modal Augmentation by Retrieval for Multimodal Federated Learning with Missing Modalities
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Poudel, Pranav, Shrestha, Prashant, Amgain, Sanskar, Shrestha, Yash Raj, Gyawali, Prashnna, and Bhattarai, Binod
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Computer Science - Computer Vision and Pattern Recognition - Abstract
Multimodal AI has demonstrated superior performance over unimodal approaches by leveraging diverse data sources for more comprehensive analysis. However, applying this effectiveness in healthcare is challenging due to the limited availability of public datasets. Federated learning presents an exciting solution, allowing the use of extensive databases from hospitals and health centers without centralizing sensitive data, thus maintaining privacy and security. Yet, research in multimodal federated learning, particularly in scenarios with missing modalities a common issue in healthcare datasets remains scarce, highlighting a critical area for future exploration. Toward this, we propose a novel method for multimodal federated learning with missing modalities. Our contribution lies in a novel cross-modal data augmentation by retrieval, leveraging the small publicly available dataset to fill the missing modalities in the clients. Our method learns the parameters in a federated manner, ensuring privacy protection and improving performance in multiple challenging multimodal benchmarks in the medical domain, surpassing several competitive baselines. Code Available: https://github.com/bhattarailab/CAR-MFL, Comment: Accepted at MICCAI 2024
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- 2024
29. Bridging the gap between community schools and rural communities in nepal using participatory action research
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Shrestha, Salpa and Dangal, Megh Raj
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- 2024
30. Energy and nutrient recovery from municipal and industrial waste and wastewater - a perspective
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Rachbauer, Lydia, Granda, Cesar B, Shrestha, Shilva, Fuchs, Werner, Gabauer, Wolfgang, Singer, Steven W, Simmons, Blake A, and Urgun-Demirtas, Meltem
- Subjects
Microbiology ,Biochemistry and Cell Biology ,Biological Sciences ,Industrial Biotechnology ,Responsible Consumption and Production ,Affordable and Clean Energy ,Anaerobic digestion ,biofilm ,carboxylate platform ,digestate treatment ,mixed microbial community ,Food Sciences ,Biotechnology ,Biochemistry and cell biology ,Industrial biotechnology - Abstract
This publication highlights the latest advancements in the field of energy and nutrient recovery from organics rich municipal and industrial waste and wastewater. Energy and carbon rich waste streams are multifaceted, including municipal solid waste, industrial waste, agricultural by-products and residues, beached or residual seaweed biomass from post-harvest processing, and food waste and are valuable resources to overcome current limitations with sustainable feedstock supply chains for biorefining approaches. The emphasis will be on the most recent scientific progress in the area, including the development of new and innovative technologies, such as microbial processes and the role of biofilms for the degradation of organic pollutants in wastewater, as well as the production of biofuels and value-added products from organic waste and wastewater streams. The carboxylate platform, which employs microbiomes to produce mixed carboxylic acids through methane-arrested anaerobic digestion, is the focus as a new conversion technology. Nutrient recycling from conventional waste streams such as wastewater and digestate, and the energetic valorization of such streams will also be discussed. The selected technologies significantly contribute to advanced waste and wastewater treatment and support the recovery and utilization of carboxylic acids as the basis to produce many useful and valuable products, including food and feed preservatives, human and animal health supplements, solvents, plasticizers, lubricants, and even biofuels such as sustainable aviation fuel.
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- 2024
31. Calorie restriction increases insulin sensitivity to promote beta cell homeostasis and longevity in mice
- Author
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dos Santos, Cristiane, Cambraia, Amanda, Shrestha, Shristi, Cutler, Melanie, Cottam, Matthew, Perkins, Guy, Lev-Ram, Varda, Roy, Birbickram, Acree, Christopher, Kim, Keun-Young, Deerinck, Thomas, Dean, Danielle, Cartailler, Jean Philippe, MacDonald, Patrick E, Hetzer, Martin, Ellisman, Mark, and Arrojo e Drigo, Rafael
- Subjects
Medical Biochemistry and Metabolomics ,Biochemistry and Cell Biology ,Biomedical and Clinical Sciences ,Biological Sciences ,Aging ,Genetics ,Diabetes ,Nutrition ,1.1 Normal biological development and functioning ,Metabolic and endocrine ,Animals ,Caloric Restriction ,Insulin-Secreting Cells ,Longevity ,Homeostasis ,Insulin Resistance ,Mice ,Male ,Diet ,High-Fat ,Mice ,Inbred C57BL ,Mitochondria ,Cell Proliferation ,Mitophagy ,Insulin ,Gene Regulatory Networks - Abstract
Caloric restriction (CR) can extend the organism life- and health-span by improving glucose homeostasis. How CR affects the structure-function of pancreatic beta cells remains unknown. We used single nucleus transcriptomics to show that CR increases the expression of genes for beta cell identity, protein processing, and organelle homeostasis. Gene regulatory network analysis reveal that CR activates transcription factors important for beta cell identity and homeostasis, while imaging metabolomics demonstrates that beta cells upon CR are more energetically competent. In fact, high-resolution microscopy show that CR reduces beta cell mitophagy to increase mitochondria mass and the potential for ATP generation. However, CR beta cells have impaired adaptive proliferation in response to high fat diet feeding. Finally, we show that long-term CR delays the onset of beta cell aging hallmarks and promotes cell longevity by reducing beta cell turnover. Therefore, CR could be a feasible approach to preserve compromised beta cell structure-function during aging and diabetes.
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- 2024
32. Mck1-mediated proteolysis of CENP-A prevents mislocalization of CENP-A for chromosomal stability in Saccharomyces cerevisiae.
- Author
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Zhang, Tianyi, Au, Wei-Chun, Ohkuni, Kentaro, Shrestha, Roshan, Kaiser, Peter, and Basrai, Munira
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CENP-A ,Cdc4 ,Cse4 ,Mck1 ,centromere ,Saccharomyces cerevisiae Proteins ,Saccharomyces cerevisiae ,Chromosomal Instability ,Proteolysis ,Chromosomal Proteins ,Non-Histone ,Centromere Protein A ,Phosphorylation ,DNA-Binding Proteins ,Cell Cycle Proteins ,Centromere ,F-Box Proteins ,Ubiquitin-Protein Ligase Complexes ,Ubiquitin-Protein Ligases - Abstract
Centromeric localization of evolutionarily conserved CENP-A (Cse4 in Saccharomyces cerevisiae) is essential for chromosomal stability. Mislocalization of overexpressed CENP-A to noncentromeric regions contributes to chromosomal instability in yeasts, flies, and humans. Overexpression and mislocalization of CENP-A observed in many cancers are associated with poor prognosis. Previous studies have shown that F-box proteins, Cdc4 and Met30 of the Skp, Cullin, F-box ubiquitin ligase cooperatively regulate proteolysis of Cse4 to prevent Cse4 mislocalization and chromosomal instability under normal physiological conditions. Mck1-mediated phosphorylation of Skp, Cullin, F-box-Cdc4 substrates such as Cdc6 and Rcn1 enhances the interaction of the substrates with Cdc4. Here, we report that Mck1 interacts with Cse4, and Mck1-mediated proteolysis of Cse4 prevents Cse4 mislocalization for chromosomal stability. Our results showed that mck1Δ strain overexpressing CSE4 (GAL-CSE4) exhibits lethality, defects in ubiquitin-mediated proteolysis of Cse4, mislocalization of Cse4, and reduced Cse4-Cdc4 interaction. Strain expressing GAL-cse4-3A with mutations in three potential Mck1 phosphorylation consensus sites (S10, S16, and T166) also exhibits growth defects, increased stability with mislocalization of Cse4-3A, chromosomal instability, and reduced interaction with Cdc4. Constitutive expression of histone H3 (Δ16H3) suppresses the chromosomal instability phenotype of GAL-cse4-3A strain, suggesting that the chromosomal instability phenotype is linked to Cse4-3A mislocalization. We conclude that Mck1 and its three potential phosphorylation sites on Cse4 promote Cse4-Cdc4 interaction and this contributes to ubiquitin-mediated proteolysis of Cse4 preventing its mislocalization and chromosomal instability. These studies advance our understanding of pathways that regulate cellular levels of CENP-A to prevent mislocalization of CENP-A in human cancers.
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- 2024
33. Hepatitis E virus in the Kathmandu Valley: Insights from a representative longitudinal serosurvey
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Katuwal, Nishan, Thapa, Melina, Shrestha, Sony, Vaidya, Krista, Bogoch, Isaac I, Shrestha, Rajeev, Andrews, Jason R, Tamrakar, Dipesh, and Aiemjoy, Kristen
- Subjects
Biomedical and Clinical Sciences ,Clinical Sciences ,Digestive Diseases ,Hepatitis ,Infectious Diseases ,Emerging Infectious Diseases ,Liver Disease ,2.4 Surveillance and distribution ,2.2 Factors relating to the physical environment ,Infection ,Good Health and Well Being ,Humans ,Nepal ,Hepatitis E ,Seroepidemiologic Studies ,Adolescent ,Adult ,Young Adult ,Hepatitis E virus ,Child ,Male ,Female ,Child ,Preschool ,Longitudinal Studies ,Infant ,Immunoglobulin G ,Hepatitis Antibodies ,Infant ,Newborn ,Incidence ,Biological Sciences ,Medical and Health Sciences ,Tropical Medicine ,Biological sciences ,Biomedical and clinical sciences ,Health sciences - Abstract
BackgroundHepatitis-E virus (HEV), an etiologic agent of acute inflammatory liver disease, is a significant cause of morbidity and mortality in South Asia. HEV is considered endemic in Nepal; but data on population-level infection transmission is sparse.MethodsWe conducted a longitudinal serosurvey in central Nepal to assess HEV exposure. At each visit, capillary blood samples were collected and analyzed for the presence of anti-HEV IgG antibodies. The study took place between February 2019 and April 2021, with up to 4 visits per participant approximately 6 months apart.ResultsWe collected 2513 samples from 923 participants aged 0-25 years, finding a seroprevalence of 4.8% and a seroincidence rate of 10.9 per 1000 person-years. Young adults and individuals consuming surface water faced the highest incidence of infection. Geospatial analysis identified potential HEV clusters, suggesting a need for targeted interventions.SignificanceOur findings demonstrate that HEV is endemic in Nepal and that the risk of infection increases with age.
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- 2024
34. Emulating Brain-like Rapid Learning in Neuromorphic Edge Computing
- Author
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Stewart, Kenneth, Neumeier, Michael, Shrestha, Sumit Bam, Orchard, Garrick, and Neftci, Emre
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Computer Science - Neural and Evolutionary Computing ,Computer Science - Artificial Intelligence - Abstract
Achieving personalized intelligence at the edge with real-time learning capabilities holds enormous promise in enhancing our daily experiences and helping decision making, planning, and sensing. However, efficient and reliable edge learning remains difficult with current technology due to the lack of personalized data, insufficient hardware capabilities, and inherent challenges posed by online learning. Over time and across multiple developmental stages, the brain has evolved to efficiently incorporate new knowledge by gradually building on previous knowledge. In this work, we emulate the multiple stages of learning with digital neuromorphic technology that simulates the neural and synaptic processes of the brain using two stages of learning. First, a meta-training stage trains the hyperparameters of synaptic plasticity for one-shot learning using a differentiable simulation of the neuromorphic hardware. This meta-training process refines a hardware local three-factor synaptic plasticity rule and its associated hyperparameters to align with the trained task domain. In a subsequent deployment stage, these optimized hyperparameters enable fast, data-efficient, and accurate learning of new classes. We demonstrate our approach using event-driven vision sensor data and the Intel Loihi neuromorphic processor with its plasticity dynamics, achieving real-time one-shot learning of new classes that is vastly improved over transfer learning. Our methodology can be deployed with arbitrary plasticity models and can be applied to situations demanding quick learning and adaptation at the edge, such as navigating unfamiliar environments or learning unexpected categories of data through user engagement., Comment: 17 page journal article. Submitted to IOP NCE
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- 2024
35. A model for horizontally restricted random square-tiled surfaces
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Fitzhugh, Nick, Schondorf, Aaron, Shrestha, Sunrose, Fallon, Sebastian Vander Ploeg, and Zeng, Thomas
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Mathematics - Geometric Topology ,Mathematics - Probability - Abstract
A square-tiled surface (STS) is a (finite, possibly branched) cover of the standard square-torus with possible branching over exactly 1 point. Alternately, STSs can be viewed as finitely many axis-parallel squares with sides glued in parallel pairs. After a labelling of the squares by $\{1, \dots, n\}$, we can describe an STS with $n$ squares using two permutations $\sigma, \tau \in S_n$, where $\sigma$ encodes how the squares are glued horizontally and $\tau$ encodes how the squares are glued vertically. Hence, a previously considered natural model for STSs with $n$ squares is $S_n \times S_n$ with the uniform distribution. We modify this model to obtain a new one: We fix $\alpha \in [0,1]$ and let $\mathcal{K}_{\mu_n}$ be a conjugacy class of $S_n$ with at most $n^\alpha$ cycles. Then $\mathcal{K}_{\mu_n} \times S_n$ with the uniform distribution is a model for STSs with restricted horizontal gluings. We deduce the asymptotic (as $n$ grows) number of components, genus distribution, most likely stratum and set of holonomy vectors of saddle connections for random STSs in this new model., Comment: 4 figures
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- 2024
36. One Year of SN 2023ixf: Breaking Through the Degenerate Parameter Space in Light-Curve Models with Pulsating Progenitors
- Author
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Hsu, Brian, Smith, Nathan, Goldberg, Jared A., Bostroem, K. Azalee, Hosseinzadeh, Griffin, Sand, David J., Pearson, Jeniveve, Hiramatsu, Daichi, Andrews, Jennifer E., Beasor, Emma R., Dong, Yize, Farah, Joseph, Galbany, LluÍs, Gomez, Sebastian, Gonzalez, Estefania Padilla, Gutiérrez, Claudia P., Howell, D. Andrew, Könyves-Tóth, Réka, McCully, Curtis, Newsome, Megan, Shrestha, Manisha, Terreran, Giacomo, Villar, V. Ashley, and Wang, Xiaofeng
- Subjects
Astrophysics - High Energy Astrophysical Phenomena ,Astrophysics - Solar and Stellar Astrophysics - Abstract
We present and analyze the extensive optical broadband photometry of the Type II SN 2023ixf up to one year after explosion. We find that, when compared to two pre-existing model grids, the pseudo-bolometric light curve is consistent with drastically different combinations of progenitor and explosion properties. This may be an effect of known degeneracies in Type IIP light-curve models. We independently compute a large grid of ${\tt MESA+STELLA}$ single-star progenitor and light-curve models with various zero-age main-sequence masses, mass-loss efficiencies, and convective efficiencies. Using the observed progenitor variability as an additional constraint, we select stellar models consistent with the pulsation period and explode them according to previously established scaling laws to match plateau properties. Our hydrodynamic modeling indicates that SN 2023ixf is most consistent with a moderate-energy ($E_{\rm exp}\approx7\times10^{50}$ erg) explosion of an initially high-mass red supergiant progenitor ($\gtrsim 17\ M_{\odot}$) that lost a significant amount of mass in its prior evolution, leaving a low-mass hydrogen envelope ($\lesssim 3\ M_{\odot}$) at the time of explosion, with a radius $\gtrsim 950\ R_{\odot}$ and a synthesized $^{56}$Ni mass of $0.07\ M_{\odot}$. We posit that previous mass transfer in a binary system may have stripped the envelope of SN 2023ixf's progenitor. The analysis method with pulsation period presented in this work offers a way to break degeneracies in light-curve modeling in the future, particularly with the upcoming Vera C.~Rubin Observatory Legacy Survey of Space and Time, when a record of progenitor variability will be more common., Comment: 18 pages, 7 figures, submitted to ApJ. Comments welcome
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- 2024
37. Revisiting Multi-Modal LLM Evaluation
- Author
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Lu, Jian, Srivastava, Shikhar, Chen, Junyu, Shrestha, Robik, Acharya, Manoj, Kafle, Kushal, and Kanan, Christopher
- Subjects
Computer Science - Artificial Intelligence ,Computer Science - Computation and Language ,Computer Science - Computer Vision and Pattern Recognition - Abstract
With the advent of multi-modal large language models (MLLMs), datasets used for visual question answering (VQA) and referring expression comprehension have seen a resurgence. However, the most popular datasets used to evaluate MLLMs are some of the earliest ones created, and they have many known problems, including extreme bias, spurious correlations, and an inability to permit fine-grained analysis. In this paper, we pioneer evaluating recent MLLMs (LLaVA 1.5, LLaVA-NeXT, BLIP2, InstructBLIP, GPT-4V, and GPT-4o) on datasets designed to address weaknesses in earlier ones. We assess three VQA datasets: 1) TDIUC, which permits fine-grained analysis on 12 question types; 2) TallyQA, which has simple and complex counting questions; and 3) DVQA, which requires optical character recognition for chart understanding. We also study VQDv1, a dataset that requires identifying all image regions that satisfy a given query. Our experiments reveal the weaknesses of many MLLMs that have not previously been reported. Our code is integrated into the widely used LAVIS framework for MLLM evaluation, enabling the rapid assessment of future MLLMs. Project webpage: https://kevinlujian.github.io/MLLM_Evaluations/
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- 2024
38. Circumstellar Interaction in the Ultraviolet Spectra of SN 2023ixf 14-66 Days After Explosion
- Author
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Bostroem, K. Azalee, Sand, David J., Dessart, Luc, Smith, Nathan, Jha, Saurabh W., Valenti, Stefano, Andrews, Jennifer E., Dong, Yize, Filippenko, Alexei V., Gomez, Sebastian, Hiramatsu, Daichi, Hoang, Emily T., Hosseinzadeh, Griffin, Howell, D. Andrew, Jencson, Jacob E., Lundquist, Michael, McCully, Curtis, Mehta, Darshana, Retamal, Nicolas E. Meza, Pearson, Jeniveve, Ravi, Aravind P., Shrestha, Manisha, and Wyatt, Samuel
- Subjects
Astrophysics - High Energy Astrophysical Phenomena ,Astrophysics - Solar and Stellar Astrophysics - Abstract
SN 2023ixf was discovered in M101 within a day of explosion and rapidly classified as a Type II supernova with flash features. Here we present ultraviolet (UV) spectra obtained with the Hubble Space Telescope 14, 19, 24, and 66 days after explosion. Interaction between the supernova ejecta and circumstellar material (CSM) is seen in the UV throughout our observations in the flux of the first three epochs and asymmetric Mg II emission on day 66. We compare our observations to CMFGEN supernova models that include CSM interaction ($\dot{M}<10^{-3}$ M$_{\odot}$ yr$^{-1}$) and find that the power from CSM interaction is decreasing with time, from $L_{\rm sh}\approx5\times10^{42}$ erg s$^{-1}$ to $L_{\rm sh}\approx1\times10^{40}$ erg s$^{-1}$ between days 14 and 66. We examine the contribution of individual atomic species to the spectra on days 14 and 19, showing that the majority of the features are dominated by iron, nickel, magnesium, and chromium absorption in the ejecta. The UV spectral energy distribution of SN 2023ixf sits between that of supernovae which show no definitive signs of CSM interaction and those with persistent signatures assuming the same progenitor radius and metallicity. Finally, we show that the evolution and asymmetric shape of the Mg II $\lambda\lambda$ 2796, 2802 emission are not unique to SN 2023ixf. These observations add to the early measurements of dense, confined CSM interaction, tracing the mass-loss history of SN 2023ixf to $\sim33$ yr prior to the explosion and the density profile to a radius of $\sim5.7\times10^{15}$ cm. They show the relatively short evolution from a quiescent red supergiant wind to high mass loss., Comment: Accepted ApJL
- Published
- 2024
39. Learning Multi-Modal Whole-Body Control for Real-World Humanoid Robots
- Author
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Dugar, Pranay, Shrestha, Aayam, Yu, Fangzhou, van Marum, Bart, and Fern, Alan
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Computer Science - Robotics ,Computer Science - Artificial Intelligence - Abstract
The foundational capabilities of humanoid robots should include robustly standing, walking, and mimicry of whole and partial-body motions. This work introduces the Masked Humanoid Controller (MHC), which supports all of these capabilities by tracking target trajectories over selected subsets of humanoid state variables while ensuring balance and robustness against disturbances. The MHC is trained in simulation using a carefully designed curriculum that imitates partially masked motions from a library of behaviors spanning standing, walking, optimized reference trajectories, re-targeted video clips, and human motion capture data. It also allows for combining joystick-based control with partial-body motion mimicry. We showcase simulation experiments validating the MHC's ability to execute a wide variety of behaviors from partially-specified target motions. Moreover, we demonstrate sim-to-real transfer on the real-world Digit V3 humanoid robot. To our knowledge, this is the first instance of a learned controller that can realize whole-body control of a real-world humanoid for such diverse multi-modal targets., Comment: Website: https://masked-humanoid.github.io/mhc/
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- 2024
40. Difficulty Estimation and Simplification of French Text Using LLMs
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Jamet, Henri, Shrestha, Yash Raj, and Vlachos, Michalis
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Computer Science - Computation and Language ,Computer Science - Artificial Intelligence - Abstract
We leverage generative large language models for language learning applications, focusing on estimating the difficulty of foreign language texts and simplifying them to lower difficulty levels. We frame both tasks as prediction problems and develop a difficulty classification model using labeled examples, transfer learning, and large language models, demonstrating superior accuracy compared to previous approaches. For simplification, we evaluate the trade-off between simplification quality and meaning preservation, comparing zero-shot and fine-tuned performances of large language models. We show that meaningful text simplifications can be obtained with limited fine-tuning. Our experiments are conducted on French texts, but our methods are language-agnostic and directly applicable to other foreign languages., Comment: 10 pages, 4 figures
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- 2024
- Full Text
- View/download PDF
41. Consent in Crisis: The Rapid Decline of the AI Data Commons
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Longpre, Shayne, Mahari, Robert, Lee, Ariel, Lund, Campbell, Oderinwale, Hamidah, Brannon, William, Saxena, Nayan, Obeng-Marnu, Naana, South, Tobin, Hunter, Cole, Klyman, Kevin, Klamm, Christopher, Schoelkopf, Hailey, Singh, Nikhil, Cherep, Manuel, Anis, Ahmad, Dinh, An, Chitongo, Caroline, Yin, Da, Sileo, Damien, Mataciunas, Deividas, Misra, Diganta, Alghamdi, Emad, Shippole, Enrico, Zhang, Jianguo, Materzynska, Joanna, Qian, Kun, Tiwary, Kush, Miranda, Lester, Dey, Manan, Liang, Minnie, Hamdy, Mohammed, Muennighoff, Niklas, Ye, Seonghyeon, Kim, Seungone, Mohanty, Shrestha, Gupta, Vipul, Sharma, Vivek, Chien, Vu Minh, Zhou, Xuhui, Li, Yizhi, Xiong, Caiming, Villa, Luis, Biderman, Stella, Li, Hanlin, Ippolito, Daphne, Hooker, Sara, Kabbara, Jad, and Pentland, Sandy
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Computer Science - Computation and Language ,Computer Science - Artificial Intelligence ,Computer Science - Machine Learning - Abstract
General-purpose artificial intelligence (AI) systems are built on massive swathes of public web data, assembled into corpora such as C4, RefinedWeb, and Dolma. To our knowledge, we conduct the first, large-scale, longitudinal audit of the consent protocols for the web domains underlying AI training corpora. Our audit of 14,000 web domains provides an expansive view of crawlable web data and how codified data use preferences are changing over time. We observe a proliferation of AI-specific clauses to limit use, acute differences in restrictions on AI developers, as well as general inconsistencies between websites' expressed intentions in their Terms of Service and their robots.txt. We diagnose these as symptoms of ineffective web protocols, not designed to cope with the widespread re-purposing of the internet for AI. Our longitudinal analyses show that in a single year (2023-2024) there has been a rapid crescendo of data restrictions from web sources, rendering ~5%+ of all tokens in C4, or 28%+ of the most actively maintained, critical sources in C4, fully restricted from use. For Terms of Service crawling restrictions, a full 45% of C4 is now restricted. If respected or enforced, these restrictions are rapidly biasing the diversity, freshness, and scaling laws for general-purpose AI systems. We hope to illustrate the emerging crises in data consent, for both developers and creators. The foreclosure of much of the open web will impact not only commercial AI, but also non-commercial AI and academic research., Comment: 41 pages (13 main), 5 figures, 9 tables
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- 2024
42. Simulations of evaporation to deep Fermi degeneracy in microwave-shielded molecules
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Wang, Reuben R. W., Biswas, Shrestha, Eppelt, Sebastian, Deng, Fulin, Luo, Xin-Yu, and Bohn, John L.
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Condensed Matter - Quantum Gases ,Physics - Atomic Physics ,Quantum Physics - Abstract
In the quest toward realizing novel quantum matter in ultracold molecular gases, we perform a numerical study of evaporative cooling in ultracold gases of microwave-shielded polar fermionic molecules. Our Monte Carlo simulations incorporate accurate two-body elastic and inelastic scattering cross sections, realistic modeling of the optical dipole trap, and the influence of Pauli blocking at low temperatures. The simulations are benchmarked against data from evaporation studies performed with ultracold NaK molecules, showing excellent agreement. We further explore the prospects for optimizing the evaporation efficiency by varying the ramp rate and duration of the evaporation trajectory. Our simulation shows that it is possible to reach $< 10\%$ of the Fermi temperature under optimal conditions even in the presence of two-body molecular losses., Comment: 12 pages, 9 figures, 2 tables
- Published
- 2024
43. The Long-lived Broadband Afterglow of Short Gamma-Ray Burst 231117A and the Growing Radio-Detected Short GRB Population
- Author
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Schroeder, Genevieve, Fong, Wen-fai, Kilpatrick, Charles D., Escorial, Alicia Rouco, Laskar, Tanmoy, Nugent, Anya E., Rastinejad, Jillian, Alexander, Kate D., Berger, Edo, Brink, Thomas G., Chornock, Ryan, de Bom, Clecio R., Dong, Yuxin, Eftekhari, Tarraneh, Filippenko, Alexei V., Fuentes-Carvajal, Celeste, Jacobson-Galan, Wynn V., Malkan, Matthew, Margutti, Raffaella, Pearson, Jeniveve, Rhodes, Lauren, Salinas, Ricardo, Sand, David J., Santana-Silva, Luidhy, Santos, Andre, Sears, Huei, Shrestha, Manisha, Smith, Nathan, Webb, Wayne, de Wet, Simon, and Yang, Yi
- Subjects
Astrophysics - High Energy Astrophysical Phenomena - Abstract
We present multiwavelength observations of the Swift short $\gamma$-ray burst GRB 231117A, localized to an underlying galaxy at redshift $z = 0.257$ at a small projected offset ($\sim 2~$kpc). We uncover long-lived X-ray (Chandra) and radio/millimeter (VLA, MeerKAT, and ALMA) afterglow emission, detected to $\sim 37~$days and $\sim 20~$days (rest frame), respectively. We measure a wide jet ($\sim 10.4^\circ$) and relatively high circumburst density ($\sim 0.07~{\rm cm}^{-3}$) compared to the short GRB population. Our data cannot be easily fit with a standard forward shock model, but they are generally well fit with the incorporation of a refreshed forward shock and a reverse shock at $< 1~$day. We incorporate GRB 231117A into a larger sample of 132 X-ray detected events, 71 of which were radio-observed (17 cm-band detections), for a systematic study of the distributions of redshifts, jet and afterglow properties, galactocentric offsets, and local environments of events with and without detected radio afterglows. Compared to the entire short GRB population, the majority of radio-detected GRBs are at relatively low redshifts ($z < 0.6$) and have high circumburst densities ($> 10^{-2}~{\rm cm}^{-3}$), consistent with their smaller ($< 8~$kpc) projected galactocentric offsets. We additionally find that 70% of short GRBs with opening angle measurements were radio-detected, indicating the importance of radio afterglows in jet measurements, especially in the cases of wide ($> 10^\circ$) jets where observational evidence of collimation may only be detectable at radio wavelengths. Owing to improved observing strategies and the emergence of sensitive radio facilities, the number of radio-detected short GRBs has quadrupled in the past decade., Comment: 30 pages, 11 figures, submitted to ApJ
- Published
- 2024
44. IDAT: A Multi-Modal Dataset and Toolkit for Building and Evaluating Interactive Task-Solving Agents
- Author
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Mohanty, Shrestha, Arabzadeh, Negar, Tupini, Andrea, Sun, Yuxuan, Skrynnik, Alexey, Zholus, Artem, Côté, Marc-Alexandre, and Kiseleva, Julia
- Subjects
Computer Science - Artificial Intelligence ,Computer Science - Computation and Language ,Computer Science - Machine Learning - Abstract
Seamless interaction between AI agents and humans using natural language remains a key goal in AI research. This paper addresses the challenges of developing interactive agents capable of understanding and executing grounded natural language instructions through the IGLU competition at NeurIPS. Despite advancements, challenges such as a scarcity of appropriate datasets and the need for effective evaluation platforms persist. We introduce a scalable data collection tool for gathering interactive grounded language instructions within a Minecraft-like environment, resulting in a Multi-Modal dataset with around 9,000 utterances and over 1,000 clarification questions. Additionally, we present a Human-in-the-Loop interactive evaluation platform for qualitative analysis and comparison of agent performance through multi-turn communication with human annotators. We offer to the community these assets referred to as IDAT (IGLU Dataset And Toolkit) which aim to advance the development of intelligent, interactive AI agents and provide essential resources for further research.
- Published
- 2024
45. Learning Decentralized Multi-Biped Control for Payload Transport
- Author
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Pandit, Bikram, Gupta, Ashutosh, Gadde, Mohitvishnu S., Johnson, Addison, Shrestha, Aayam Kumar, Duan, Helei, Dao, Jeremy, and Fern, Alan
- Subjects
Computer Science - Robotics ,Computer Science - Artificial Intelligence - Abstract
Payload transport over flat terrain via multi-wheel robot carriers is well-understood, highly effective, and configurable. In this paper, our goal is to provide similar effectiveness and configurability for transport over rough terrain that is more suitable for legs rather than wheels. For this purpose, we consider multi-biped robot carriers, where wheels are replaced by multiple bipedal robots attached to the carrier. Our main contribution is to design a decentralized controller for such systems that can be effectively applied to varying numbers and configurations of rigidly attached bipedal robots without retraining. We present a reinforcement learning approach for training the controller in simulation that supports transfer to the real world. Our experiments in simulation provide quantitative metrics showing the effectiveness of the approach over a wide variety of simulated transport scenarios. In addition, we demonstrate the controller in the real-world for systems composed of two and three Cassie robots. To our knowledge, this is the first example of a scalable multi-biped payload transport system., Comment: Submitted to CoRL 2024, Project website: decmbc.github.io
- Published
- 2024
46. Testing particle acceleration in blazar jets with continuous high-cadence optical polarization observations
- Author
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Liodakis, Ioannis, Kiehlmann, Sebastian, Marscher, Alan P., Zhang, Haocheng, Blinov, Dmitry, Jorstad, Svetlana G., Agudo, Iván, Benítez, Erika, Berdyugin, Andrei, Bonnoli, Giacomo, Casadio, Carolina, Chen, Chien-Ting, Chen, Wen-Ping, Ehlert, Steven R., Escudero, Juan, Grishina, Tatiana S., Hiriart, David, Hsu, Angela, Imazawa, Ryo, Jermak, Helen E., Jose, Jincen, Kaaret, Philip, Kopatskaya, Evgenia N., Lalchand, Bhavana, Larionova, Elena G., Lindfors, Elina, López, José M., McCall, Callum, Morozova, Daria A., Palaiologou, Efthymios, Pandey, Shivangi, Poutanen, Juri, Rakshit, Suvendu, Reig, Pablo, Sasada, Mahito, Savchenko, Sergey S., Shablovinskaya, Elena, Neha, Sharma, Shrestha, Manisha, Steele, Iain A., Troitskiy, Ivan S., Troitskaya, Yulia V., Uemura, Makoto, Vasilyev, Andrey A., Weaver, Zachary, Wiersema, Klaas, and Weisskopf, Martin C.
- Subjects
Astrophysics - High Energy Astrophysical Phenomena - Abstract
Variability can be the pathway to understanding the physical processes in astrophysical jets, however, the high-cadence observations required to test particle acceleration models are still missing. Here we report on the first attempt to produce continuous, >24 hour polarization light curves of blazars using telescopes distributed across the globe and the rotation of the Earth to avoid the rising Sun. Our campaign involved 16 telescopes in Asia, Europe, and North America. We observed BL Lacertae and CGRaBS J0211+1051 for a combined 685 telescope hours. We find large variations in the polarization degree and angle for both sources in sub-hour timescales as well as a ~180 degree rotation of the polarization angle in CGRaBS J0211+1051 in less than two days. We compared our high-cadence observations to Particle-In-Cell magnetic reconnection and turbulent plasma simulations. We find that although the state of the art simulation frameworks can produce a large fraction of the polarization properties, they do not account for the entirety of the observed polarization behavior in blazar jets., Comment: 20 pages, 15 figures, 2 tables, accepted for publication in A&A. The data used in the paper are available here: https://doi.org/10.7910/DVN/IETSXS
- Published
- 2024
- Full Text
- View/download PDF
47. First Measurement of Deeply Virtual Compton Scattering on the Neutron with Detection of the Active Neutron
- Author
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CLAS Collaboration, Hobart, A., Niccolai, S., Čuić, M., Kumerički, K., Achenbach, P., Alvarado, J. S., Armstrong, W. R., Atac, H., Avakian, H., Baashen, L., Baltzell, N. A., Barion, L., Bashkanov, M., Battaglieri, M., Benkel, B., Benmokhtar, F., Bianconi, A., Biselli, A. S., Boiarinov, S., Bondi, M., Booth, W. A., Bossù, F., Brinkmann, K. -Th., Briscoe, W. J., Brooks, W. K., Bueltmann, S., Burkert, V. D., Cao, T., Capobianco, R., Carman, D. S., Chatagnon, P., Ciullo, G., Cole, P. L., Contalbrigo, M., D'Angelo, A., Dashyan, N., De Vita, R., Defurne, M., Deur, A., Diehl, S., Dilks, C., Djalali, C., Dupre, R., Egiyan, H., Alaoui, A. El, Fassi, L. El, Elouadrhiri, L., Fegan, S., Filippi, A., Fogler, C., Gates, K., Gavalian, G., Gilfoyle, G. P., Glazier, D., Gothe, R. W., Gotra, Y., Guidal, M., Hafidi, K., Hakobyan, H., Hattawy, M., Hauenstein, F., Heddle, D., Holtrop, M., Ilieva, Y., Ireland, D. G., Isupov, E. L., Jiang, H., Jo, H. S., Joo, K., Kageya, T., Kim, A., Kim, W., Klimenko, V., Kripko, A., Kubarovsky, V., Kuhn, S. E., Lanza, L., Leali, M., Lee, S., Lenisa, P., Li, X., MacGregor, I. J. D., Marchand, D., Mascagna, V., Maynes, M., McKinnon, B., Meziani, Z. E., Migliorati, S., Milner, R. G., Mineeva, T., Mirazita, M., Mokeev, V., Camacho, C. Muñoz, Nadel-Turonski, P., Naidoo, P., Neupane, K., Niculescu, G., Osipenko, M., Pandey, P., Paolone, M., Pappalardo, L. L., Paremuzyan, R., Pasyuk, E., Paul, S. J., Phelps, W., Pilleux, N., Pokhrel, M., Rafael, S. Polcher, Poudel, J., Price, J. W., Prok, Y., Reed, T., Richards, J., Ripani, M., Ritman, J., Rossi, P., Golubenko, A. A., Salgado, C., Schadmand, S., Schmidt, A., Scott, Marshall B. C., Seroka, E. M., Sharabian, Y. G., Shirokov, E. V., Shrestha, U., Sparveris, N., Spreafico, M., Stepanyan, S., Strakovsky, I. I., Strauch, S., Tan, J. A., Trotta, N., Tyson, R., Ungaro, M., Vallarino, S., Venturelli, L., Tommaso, V., Voskanyan, H., Voutier, E., Watts, D. P, Wei, X., Williams, R., Wood, M. H., Xu, L., Zachariou, N., Zhang, J., Zhao, Z. W., and Zurek, M.
- Subjects
High Energy Physics - Experiment ,Nuclear Experiment - Abstract
Measuring Deeply Virtual Compton Scattering on the neutron is one of the necessary steps to understand the structure of the nucleon in terms of Generalized Parton Distributions (GPDs). Neutron targets play a complementary role to transversely polarized proton targets in the determination of the GPD $E$. This poorly known and poorly constrained GPD is essential to obtain the contribution of the quarks' angular momentum to the spin of the nucleon. DVCS on the neutron was measured for the first time selecting the exclusive final state by detecting the neutron, using the Jefferson Lab longitudinally polarized electron beam, with energies up to 10.6 GeV, and the CLAS12 detector. The extracted beam-spin asymmetries, combined with DVCS observables measured on the proton, allow a clean quark-flavor separation of the imaginary parts of the GPDs $H$ and $E$., Comment: 7 pages, 6 figures
- Published
- 2024
48. Emergent Dynamics in Heterogeneous Life-Like Cellular Automata
- Author
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Shrestha, Aarati, Reimers, Felix, Jain, Sanyam, Baldini, Paolo, Braccini, Michele, Roli, Andrea, and Nichele, Stefano
- Subjects
Nonlinear Sciences - Cellular Automata and Lattice Gases ,Computer Science - Emerging Technologies - Abstract
The Game of Life (GoL), one well known 2D cellular automaton, does not typically ensure interesting long-term phenotypic dynamics. Therefore, while being Turing complete, GoL cannot be said to be open-ended. In this work, we extend GoL with the opportunity for local mutations, thus enabling a heterogeneous life-like cellular automaton guided by an evolutionary inner loop. Additionally, we introduce the concept of cell ageing to ensure that cell aliveness (activated by inheritance with variation, and controlled by ageing) and actual cell computation (governed by life-like rules on local neighborhoods) are kept conceptually separated. We conduct an experimental campaign to identify suitable parameters that produce long-term phenotypic dynamics and favor genotypic innovations., Comment: 16 pages, 9 Figures
- Published
- 2024
49. Bright electrically contacted circular Bragg grating resonators with deterministically integrated quantum dots
- Author
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Wijitpatima, Setthanat, Auler, Normen, Mudi, Priyabata, Funk, Timon, Barua, Avijit, Shrestha, Binamra, Limame, Imad, Rodt, Sven, Reuter, Dirk, and Reitzenstein, Stephan
- Subjects
Condensed Matter - Mesoscale and Nanoscale Physics ,Physics - Applied Physics - Abstract
Cavity-enhanced emission of electrically controlled semiconductor quantum dots is essential in developing bright quantum devices for real-world quantum photonic applications. Combining the circular Bragg grating (CBG) approach with a PIN-diode structure, we propose and implement an innovative concept for ridge-based electrically-contacted CBG resonators. Through fine-tuning of device parameters in numerical simulations and deterministic nanoprocessing, we produced electrically controlled single quantum dot CBG resonators with excellent electro-optical emission properties. These include multiple wavelength-tunable emission lines and a photon extraction efficiency (PEE) of up to (30.4$\pm$3.4)%, where refined numerical optimization based on experimental findings suggests a substantial improvement, promising PEE >50%. Additionally, the developed quantum light sources yield single-photon purity reaching (98.8$\pm$0.2)% [post-selected: (99.5$\pm$0.3)%] and a photon indistinguishability of (25.8$\pm$2.1)% [post-selected: (92.8$\pm$4.8)%]. Our results pave the way for high-performance quantum devices with combined cavity enhancement and deterministic charge-environment controls, advancing the development of photonic quantum information systems such as complex quantum repeater networks.
- Published
- 2024
50. Real-time Deformation Correction in Additively Printed Flexible Antenna Arrays
- Author
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Poolakkal, Sreeni, Islam, Abdullah, Bansal, Shrestha, Rao, Arpit, Dabrowski, Ted, Kwan, Kalsi, Mishra, Amit, Xu, Quiyan, Ghaderi, Erfan, Lall, Pradeep, Shekhar, Sudip, Navarro, Julio, Ren, Shenqiang, Williams, John, and Gupta, Subhanshu
- Subjects
Electrical Engineering and Systems Science - Signal Processing ,Physics - Applied Physics - Abstract
Conformal phased arrays provide multiple degrees of freedom to the scan angle, which is typically limited by antenna aperture in rigid arrays. Silicon-based RF signal processing offers reliable, reconfigurable, multi-functional, and compact control for conformal phased arrays that can be used for on-the-move communication. While the lightweight, compactness, and shape-changing properties of the conformal phased arrays are attractive, these features result in dynamic deformation of the array during motion leading to significant dynamic beam pointing errors. We propose a silicon-based, compact, reconfigurable solution to self-correct these dynamic deformation-induced beam pointing errors. Furthermore, additive printing is leveraged to enhance the flexibility of the conformal phased arrays, as the printed conductive ink is more flexible than bulk copper and can be easily deposited on flexible sheets using different printing tools, providing an environmentally-friendly solution for large-scale production. The inks such as conventional silver inks are expensive and copper-based printable inks suffer from spontaneous metal oxidation that alters trace impedance and degrades beamforming performance. This work uses a low-cost molecular copper decomposition ink with reliable RF properties at different temperature and strain to print the proposed intelligent conformal phased array operating at 2.1 GHz. Proof-of-concept prototype $2\times2$ array self-corrects the deformation induces beampointing error with an error $<1.25^\circ$. The silicon based array processing part occupying only 2.58 mm$^2$ area and 83 mW power per tile.
- Published
- 2024
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