1,529,218 results on '"Dan, A."'
Search Results
2. Special Education Identification throughout the COVID-19 Pandemic. Research Brief No. 37-0624
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National Center for Analysis of Longitudinal Data in Education Research (CALDER) at American Institutes for Research (AIR), Roddy Theobald, Dan Goldhaber, and Andrew Katz
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We use student-level data on elementary special education identification from Washington state to explore student identification rates in the months immediately after the onset of the COVID-19 pandemic and over 2 subsequent years. Special education identification rates dropped dramatically in March 2020 through the end of the 2019-20 school year and remained below historical norms through 2020-21 before returning to pre-pandemic levels early in 2021-22. The magnitude of these effects implies that over 8,000 fewer elementary students were identified for special education services during the pandemic in Washington than would have been expected based on prior trends.
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- 2024
3. Benchmarking LLM Guardrails in Handling Multilingual Toxicity
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Yang, Yahan, Dan, Soham, Roth, Dan, and Lee, Insup
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Computer Science - Computation and Language - Abstract
With the ubiquity of Large Language Models (LLMs), guardrails have become crucial to detect and defend against toxic content. However, with the increasing pervasiveness of LLMs in multilingual scenarios, their effectiveness in handling multilingual toxic inputs remains unclear. In this work, we introduce a comprehensive multilingual test suite, spanning seven datasets and over ten languages, to benchmark the performance of state-of-the-art guardrails. We also investigates the resilience of guardrails against recent jailbreaking techniques, and assess the impact of in-context safety policies and language resource availability on guardrails' performance. Our findings show that existing guardrails are still ineffective at handling multilingual toxicity and lack robustness against jailbreaking prompts. This work aims to identify the limitations of guardrails and to build a more reliable and trustworthy LLMs in multilingual scenarios.
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- 2024
4. The Green Monster hiding in front of Cas A: JWST reveals a dense and dusty circumstellar structure pockmarked by ejecta interactions
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De Looze, Ilse, Milisavljevic, Dan, Temim, Tea, Dickinson, Danielle, Fesen, Robert, Arendt, Richard G., Chastenet, Jeremy, Orlando, Salvatore, Vink, Jacco, Barlow, Michael J., Kirchschlager, Florian, Priestley, Felix D., Raymond, John C., Rho, Jeonghee, Sartorio, Nina S., Scheffler, Tassilo, Schmidt, Franziska, Blair, William P., Fox, Ori, Fryer, Christopher, Janka, Hans-Thomas, Koo, Bon-Chul, Laming, J. Martin, Matsuura, Mikako, Patnaude, Dan, Relano, Monica, Rest, Armin, Schmidt, Judy, Smith, Nathan, and Sravan, Niharika
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Astrophysics - High Energy Astrophysical Phenomena ,Astrophysics - Solar and Stellar Astrophysics - Abstract
JWST observations of the young Galactic supernova remnant Cassiopeia A revealed an unexpected structure seen as a green emission feature in colored composite MIRI F1130W and F1280W images - hence dubbed the Green Monster - that stretches across the central parts of the remnant in projection. Combining the kinematic information from NIRSpec and MIRI MRS with the multi-wavelength imaging from NIRCam and MIRI, we associate the Green Monster with circumstellar material that was lost during an asymmetric mass-loss phase. MIRI images are dominated by dust emission but its spectra show emission lines from Ne, H and Fe with low radial velocities indicative of a CSM nature. An X-ray analysis of this feature in a companion paper (Vink et al. 2024) supports its CSM nature and detects significant blue shifting, thereby placing the Green Monster on the near side, in front of the Cas A SN remnant. The most striking features of the Green Monster are dozens of almost perfectly circular 1" - 3" sized holes, most likely created by interaction between high-velocity SN ejecta material and the CSM. Further investigation is needed to understand whether these holes were formed by small 8000-10500 km/s N-rich ejecta knots that penetrated and advanced out ahead of the remnant's 5000 - 6000 km/s outer blastwave, or by narrow ejecta fingers that protrude into the forward-shocked CSM. The detection of the Green Monster provides further evidence of the highly asymmetric mass-loss that Cas A's progenitor star underwent prior to explosion., Comment: 28 pages, 12 figures, resubmitted to ApJL after minor revision, comments welcome
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- 2024
5. The Biltmore Forest School and the Establishment of Forestry Education in America
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Dan Barry Croom
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The Biltmore Forest School, despite its unusual existence within the affluent Biltmore Estate, played a crucial role in the early 20th-century American forestry movement. Founded by Carl A. Schenck and supported by George Vanderbilt II, the school aimed to educate foresters and promote sustainable forest management. However, many aspects of the Biltmore experiment failed due to the new and untested nature of forestry science in America. This experiment exposed a fundamental divide in forestry education, with Gifford Pinchot advocating for conservation-centered teaching while Schenck believed in the economic viability of lumber production. Ultimately, the Biltmore Forest School offered valuable vocational education for young men but could not address the broader goals of forestry education. The emergence of other forestry schools in the early 20th century led to the school's demise. The larger purpose of forestry education was rooted in scientific forestry, focusing on profitable production, renewable yield, and forest improvement, principles echoed in modern forest conservation efforts. The Biltmore Forest School closed in 1914 due to low enrollment. That same year, George Vanderbilt died. His widow Edith eventually sold the forest, which grew to 500,000 acres, to the United States Forest Service. Edith Vanderbilt's vision of private forest land as a public trust contributed to the establishment of Pisgah National Forest, preserving the pioneering work of Vanderbilt, Schenck, and Pinchot in forest conservation for the benefit of the American people.
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- 2024
6. Four Years of Pandemic-Era Emergency Licenses: Retention and Effectiveness of Emergency-Licensed Massachusetts Teachers over Time. Working Paper No. 299-0424
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National Center for Analysis of Longitudinal Data in Education Research (CALDER) at American Institutes for Research (AIR), Ben Backes, James Cowan, Dan Goldhaber, and Roddy Theobald
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Most states responded to the onset of the pandemic by temporarily granting teachers Emergency licenses. These licenses allowed teachers to work in classrooms without passing the typical licensure exams. Since then, several states have extended their use of Emergency licenses, raising questions about how these policies impact the composition of the teacher workforce and student outcomes. In this paper, we examine the result of these policies using data on multiple cohorts of Emergency licensed teachers (ELTs) who taught in Massachusetts between 2021 and 2023. We find that ELTs were slightly more likely to remain in the same school and in the teaching workforce than teachers from other entry routes. However, ELTs' students scored significantly lower on standardized tests in math and science than other students in the same school and same year. Our findings are at odds with earlier, more positive assessments of Emergency licensure in Massachusetts. Our updated results appear to be driven by more recent cohorts of ELTs, rather than the teachers who received Emergency licenses at the start of the pandemic. Overall, this study suggests policymakers should be cautious when drawing sweeping conclusions about the impacts of teacher licensure based solely on the earliest cohort of teachers who obtained pandemic-era Emergency licenses.
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- 2024
7. ESSER Funding and School System Jobs: Evidence from Job Posting Data. Working Paper No. 297-0424
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National Center for Analysis of Longitudinal Data in Education Research (CALDER) at American Institutes for Research (AIR), Dan Goldhaber, Grace Falken, and Roddy Theobald
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The Elementary and Secondary School Emergency Relief Fund (ESSER) was the largest onetime federal investment in K-12 schools in history, funneling almost $200 billion to states and school districts. We use novel data from Washington State to investigate the extent to which ESSER funding causally influenced spending on school personnel. We argue one cannot infer this directly from ESSER claims data because of the fungibility of school budgets. Thus, we rely on a more direct signal of district hiring decisions: public education job postings scraped from district hiring websites. To address endogeneity concerns, our preferred approach employs an instrumental variables strategy that exploits a formula mechanism used to determine Title I funding for 2020-21 (and thus ESSER allocations in 2022) based on the number of Title I formula-eligible children. We find strong, arguably causal, evidence that public school hiring increased in response to the availability of ESSER funding. Specifically, we estimate that each $1,000 in ESSER allocations caused districts to seek to hire $206 in additional staff, disproportionately teachers. These estimates suggest that roughly 12,000 new staff (including 5,100 teachers) were hired in Washington because of ESSER. In the absence of new funding, school staffing budgets will likely need to contract substantially following the sunset of ESSER.
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- 2024
8. Departmentalized Instruction and Elementary School Effectiveness. Working Paper No. 298-0424
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National Center for Analysis of Longitudinal Data in Education Research (CALDER) at American Institutes for Research (AIR), Ben Backes, James Cowan, and Dan Goldhaber
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Departmentalized instruction, in which teachers specialize in one or more core subjects and instruct multiple groups of students in a day, has become increasingly prominent in elementary schools. Using 8 years of data from Massachusetts and a difference-in-differences design, we estimate the effects of departmentalization on student achievement. We find that departmentalization has positive effects in English language arts (ELA) and science and mixed evidence of positive effects in math. These positive effects are not driven by teacher productivity improvements: Consistent with prior findings on teacher specialization, teachers are less effective when specializing in math and no more effective in ELA than when teaching self-contained classrooms. Rather, consistent with the theoretical underpinnings for specialization, departmentalized schools tend to assign teachers to their stronger subjects.
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- 2024
9. Shaping the STEM Teacher Workforce: What University Faculty Value about Teacher Applicants. Working Paper No. 295-0324
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National Center for Analysis of Longitudinal Data in Education Research (CALDER) at American Institutes for Research (AIR), Dan Goldhaber, Roddy Theobald, Amy Roth McDuffie, David Slavit, Jennifer Dechaine-Berkas, John M. Krieg, and Emma Dewil
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Who ends up in the teacher workforce is greatly influenced by who is admitted into teacher education programs (TEPs). To better understand how the preferences of teacher education faculty might shape admissions of STEM teacher candidates, we surveyed faculty who teach content or methods courses to STEM teacher candidates across five universities. Faculty reported that they most value information collected from individual interviews with applicants and data on the number of STEM courses taken in college and their performance in these courses, and least value data on university admissions tests, high school GPA, and teacher licensure test scores. When we investigate faculty members' revealed preferences through a conjoint analysis, we find that faculty most value applicants who have worked with students from diverse backgrounds and applicants from a marginalized racial or ethnic community, and least value whether they received high grades in math and/or science courses. Finally, we find significant variation in these perceptions across respondents in different faculty roles, who teach different courses, and from different institutions: for example, Arts and Sciences faculty tend to value TEP applicants' performance in college STEM courses relatively more than STEM education faculty, while STEM education faculty tend to value applicants' race and ethnicity relatively more than Arts and Sciences faculty.
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- 2024
10. Access to Success: Insights for Implementing a Multiple Measures Assessment System
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Columbia University, Center for the Analysis of Postsecondary Readiness (CAPR), Columbia University, Community College Research Center (CCRC), MDRC, Elizabeth M. Kopko, Hollie Daniels Sarica, Dan Cullinan, Hanna Nichols, Ellen Wasserman, and Sarahi Hernandez
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Multiple measures assessment (MMA) is an alternative placement system that involves the consideration of alternative measures of students' performance--such as high school grades or GPA--in addition to or in place of standardized test scores to better place students. While the evidence for MMA is strong, placement reform has yet to spread to many colleges and states. Moreover, despite growing support for MMA, many colleges may not be implementing the most promising MMA systems, and some may shift back to standardized testing in the post-pandemic environment. CAPR has sought to assist colleges and states nationwide with the adoption and implementation of MMA practices that place more students--and allow more students to be successful--in college-level courses. As part of these efforts, CAPR worked with colleges in Arkansas and Texas to adopt and expand MMA. The findings in this report are derived from interviews with personnel from 12 two- and four-year public colleges in those states that went through considerable effort to improve their placement systems and to make them sustainable on a large scale. The study focused on three questions: What was the design of the MMA system at each college? How were colleges adopting MMA practices and what were key facilitators and hindrances? And what was the average cost of implementation? The authors found that adoption of MMA at each study college required collaboration among institutional leaders, administrators, faculty members, and advisors. The report highlights the roles of key actors in the adoption of MMA and the important role that state context and policies played in implementation. It also describes challenges that colleges had to overcome during implementation, such as obtaining staff buy-in, managing student data, and ensuring sufficient staffing.
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- 2024
11. Rethinking Normalization Strategies and Convolutional Kernels for Multimodal Image Fusion
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He, Dan, Wang, Guofen, Li, Weisheng, Shu, Yucheng, Li, Wenbo, Yang, Lijian, Huang, Yuping, and Li, Feiyan
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Computer Science - Computer Vision and Pattern Recognition ,Computer Science - Artificial Intelligence - Abstract
Multimodal image fusion (MMIF) aims to integrate information from different modalities to obtain a comprehensive image, aiding downstream tasks. However, existing methods tend to prioritize natural image fusion and focus on information complementary and network training strategies. They ignore the essential distinction between natural and medical image fusion and the influence of underlying components. This paper dissects the significant differences between the two tasks regarding fusion goals, statistical properties, and data distribution. Based on this, we rethink the suitability of the normalization strategy and convolutional kernels for end-to-end MMIF.Specifically, this paper proposes a mixture of instance normalization and group normalization to preserve sample independence and reinforce intrinsic feature correlation.This strategy promotes the potential of enriching feature maps, thus boosting fusion performance. To this end, we further introduce the large kernel convolution, effectively expanding receptive fields and enhancing the preservation of image detail. Moreover, the proposed multipath adaptive fusion module recalibrates the decoder input with features of various scales and receptive fields, ensuring the transmission of crucial information. Extensive experiments demonstrate that our method exhibits state-of-the-art performance in multiple fusion tasks and significantly improves downstream applications. The code is available at https://github.com/HeDan-11/LKC-FUNet.
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- 2024
12. DarkSHINE Baseline Design Report: Physics Prospects and Detector Technologies
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Chen, Jing, Chen, Ji-Yuan, Chen, Jun-Feng, Chen, Xiang, Fu, Chang-Bo, Guo, Jun, Guo, Yi-Han, Khaw, Kim Siang, Li, Jia-Lin, Li, Liang, Li, Shu, Lin, Yu-ming, Liu, Dan-Ning, Liu, Kang, Liu, Kun, Liu, Qi-Bin, Liu, Zhi, Lu, Ze-Jia, Lv, Meng, Song, Si-Yuan, Sun, Tong, Tang, Jian-Nan, Wan, Wei-Shi, Wang, Dong, Wang, Xiao-Long, Wang, Yu-Feng, Wang, Zhen, Wang, Zi-Rui, Wu, Wei-Hao, Yang, Hai-Jun, Yang, Lin, Yang, Yong, Yu, Dian, Yuan, Rui, Zhang, Jun-Hua, Zhang, Yu-Lei, Zhang, Yun-Long, Zhao, Zhi-Yu, Zhou, Bai-Hong, Zhu, Chun-Xiang, Zhu, Xu-Liang, and Zhu, Yi-Fan
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Physics - Instrumentation and Detectors ,High Energy Physics - Experiment - Abstract
DarkSHINE is a newly proposed fixed-target experiment initiative to search for the invisible decay of Dark Photon via missing energy/momentum signatures, based on the high repetition rate electron beam to be deployed/delivered by the Shanghai High repetition rate XFEL and Extreme light facility (SHINE). This report elaborates the baseline design of DarkSHINE experiment by introducing the physics goals, experimental setups, details of each sub-detector system technical designs, signal and backgground modelings, expected search sensitivities and future prospects, which mark an important step towards the further prototyping and technical demonstrations.
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- 2024
13. Application of Optical Tweezers in the Study of Emulsions for Multiple Applications
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Ma, Qifei, Jin, Huaizhou, Shang, Xiaoxiao, Pardy, Tamas, Scheler, Ott, Bartkova, Simona, Cojoc, Dan, Garoli, Denis, and Jin, Shangzhong
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Physics - Optics - Abstract
Emulsions are ubiquitous in everyday life and find applications in various industries. Optical tweezers (OTs) have emerged as the preferred method for studying emulsion dynamics. In this review, we first introduce the theory of optical trapping and emulsion stability. We then survey applications in the manipulation of emulsions, stability mechanism, the processes of aggregation and coalescence, and important responsive and switchable behaviors. And we overview the instrumentation framework of various OT setups, and evaluate their complexity and cost with a view towards the democratization of this technology. Following this, we delve into basic experimentation methods, the challenges associated with using OTs in emulsion applications. Additionally, we present a promising research outlook, including studies on stability mechanism of emulsions stabilized by compound or mixed emulsifiers or rigid or soft particles, as well as dynamic processes of responsive or functional emulsions.
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- 2024
14. The Impact of Social Value Orientation on Nash Equilibria of Two Player Quadratic Games
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Calderone, Dan and Oishi, Meeko
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Mathematics - Optimization and Control - Abstract
We consider two player quadratic games in a cooperative framework known as social value orientation, motivated by the need to account for complex interactions between humans and autonomous agents in dynamical systems. Social value orientation is a framework from psychology, that posits that each player incorporates the other player's cost into their own objective function, based on an individually pre-determined degree of cooperation. The degree of cooperation determines the weighting that a player puts on their own cost relative to the other player's cost. We characterize the Nash equilibria of two player quadratic games under social value orientation by creating expansions that elucidate the relative difference between this new equilibria (which we term the SVO-Nash equilibria) and more typical equilibria, such as the competitive Nash equilibria, individually optimal solutions, and the fully cooperative solution. Specifically, each expansion parametrizes the space of cooperative Nash equilibria as a family of one-dimensional curves where each curve is computed by solving an eigenvalue problem. We show that both bounded and unbounded equilibria may exist. For equilibria that are bounded, we can identify bounds as the intersection of various ellipses; for equilibria that are unbounded, we characterize conditions under which unboundedness will occur, and also compute the asymptotes that the unbounded solutions follow. We demonstrate these results in trajectory coordination scenario modeled as a linear time varying quadratic game.
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- 2024
15. A Conjecture on Group Decision Accuracy in Voter Networks through the Regularized Incomplete Beta Function
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Braha, Dan and de Aguiar, Marcus A. M.
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Statistics - Methodology ,Computer Science - Computer Science and Game Theory ,Computer Science - Social and Information Networks - Abstract
This paper presents a conjecture on the regularized incomplete beta function in the context of majority decision systems modeled through a voter framework. We examine a network where voters interact, with some voters fixed in their decisions while others are free to change their states based on the influence of their neighbors. We demonstrate that as the number of free voters increases, the probability of selecting the correct majority outcome converges to $1-I_{0.5}(\alpha,\beta)$, where $I_{0.5}(\alpha,\beta)$ is the regularized incomplete beta function. The conjecture posits that when $\alpha > \beta$, $1-I_{0.5}(\alpha,\beta) > \alpha/(\alpha+\beta)$, meaning the group's decision accuracy exceeds that of an individual voter. We provide partial results, including a proof for integer values of $\alpha$ and $\beta$, and support the general case using a probability bound. This work extends Condorcet's Jury Theorem by incorporating voter dependence driven by network dynamics, showing that group decision accuracy can exceed individual accuracy under certain conditions., Comment: 14 pages, 1 figure
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- 2024
16. Advances in quantum imaging
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Defienne, Hugo, Bowen, Warwick P., Chekhova, Maria, Lemos, Gabriela Barreto, Oron, Dan, Ramelow, Sven, Treps, Nicolas, and Faccio, Daniele
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Quantum Physics - Abstract
Modern imaging technologies are widely based on classical principles of light or electromagnetic wave propagation. They can be remarkably sophisticated, with recent successes ranging from single molecule microscopy to imaging far-distant galaxies. However, new imaging technologies based on quantum principles are gradually emerging. They can either surpass classical approaches or provide novel imaging capabilities that would not otherwise be possible. {Here }we provide an overview {of the most recently developed quantum imaging systems, highlighting the non-classical properties of sources such as bright squeezed light, entangled photons, and single-photon emitters that enable their functionality.} We outline potential upcoming trends and the associated challenges, all driven by a central inquiry, which is to understand whether quantum light can make visible the invisible.
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- 2024
- Full Text
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17. Simons Lectures on Categorical Symmetries
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Costa, Davi, Córdova, Clay, Del Zotto, Michele, Freed, Dan, Gödicke, Jonte, Hofer, Aaron, Jordan, David, Morgante, Davide, Moscrop, Robert, Ohmori, Kantaro, Gårding, Elias Riedel, Scheimbauer, Claudia, and Švraka, Anja
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Mathematical Physics ,High Energy Physics - Theory ,Mathematics - Algebraic Topology ,Mathematics - Category Theory ,Mathematics - Quantum Algebra - Abstract
Global Categorical Symmetries are a powerful new tool for analyzing quantum field theories. This volume compiles lecture notes from the 2022 and 2023 summer schools on Global Categorical Symmetries, held at the Perimeter Institute for Theoretical Physics and at the Swiss Map Research Station in Les Diableret. Specifically, this volume collects the lectures: * An introduction to symmetries in quantum field theory, Kantaro Ohmori * Introduction to anomalies in quantum field theory, Clay C\'ordova * Symmetry Categories 101, Michele Del Zotto * Applied Cobordism Hypothesis, David Jordan * Finite symmetry in QFT, Daniel S. Freed These volumes are devoted to interested newcomers: we only assume (basic) knowledge of quantum field theory (QFT) and some relevant maths. We try to give appropriate references for non-standard materials that are not covered. Our aim in this first volume is to illustrate some of the main questions and ideas together with some of the methods and the techniques necessary to begin exploring global categorical symmetries of QFTs., Comment: Lecture notes from the Summer Schools of the Simons Collaboration on Global Categorical Symmetries
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- 2024
18. An improved multiplicity bound for eigenvalues of the clamped disk
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Mangoubi, Dan and Rosenblatt, Daniel
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Mathematics - Spectral Theory ,Mathematics - Number Theory - Abstract
We prove that no eigenvalue of the clamped disk has multiplicity greater than four. This improves upon a previous bound. Exploiting a linear recursion formula of order two for cross-product Bessel functions in which the coefficients are non-rational functions satisfying a non-linear algebraic recursion, we show that higher multiplicity eigenvalues must be algebraic, in contradiction with the Siegel-Shidlovskii theory., Comment: 7 pages
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- 2024
19. TomoGRAF: A Robust and Generalizable Reconstruction Network for Single-View Computed Tomography
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Xu, Di, Yang, Yang, Liu, Hengjie, Lyu, Qihui, Descovich, Martina, Ruan, Dan, and Sheng, Ke
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Electrical Engineering and Systems Science - Image and Video Processing ,Computer Science - Computer Vision and Pattern Recognition - Abstract
Computed tomography (CT) provides high spatial resolution visualization of 3D structures for scientific and clinical applications. Traditional analytical/iterative CT reconstruction algorithms require hundreds of angular data samplings, a condition that may not be met in practice due to physical and mechanical limitations. Sparse view CT reconstruction has been proposed using constrained optimization and machine learning methods with varying success, less so for ultra-sparse view CT reconstruction with one to two views. Neural radiance field (NeRF) is a powerful tool for reconstructing and rendering 3D natural scenes from sparse views, but its direct application to 3D medical image reconstruction has been minimally successful due to the differences between optical and X-ray photon transportation. Here, we develop a novel TomoGRAF framework incorporating the unique X-ray transportation physics to reconstruct high-quality 3D volumes using ultra-sparse projections without prior. TomoGRAF captures the CT imaging geometry, simulates the X-ray casting and tracing process, and penalizes the difference between simulated and ground truth CT sub-volume during training. We evaluated the performance of TomoGRAF on an unseen dataset of distinct imaging characteristics from the training data and demonstrated a vast leap in performance compared with state-of-the-art deep learning and NeRF methods. TomoGRAF provides the first generalizable solution for image-guided radiotherapy and interventional radiology applications, where only one or a few X-ray views are available, but 3D volumetric information is desired.
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- 2024
20. Reference Signal-Based Waveform Design for Integrated Sensing and Communications System
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Lyu, Ming, Chen, Hao, Wang, Dan, Feng, Guangyin, Qiu, Chen, and Xu, Xiaodong
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Electrical Engineering and Systems Science - Signal Processing - Abstract
Integrated sensing and communications (ISAC) as one of the key technologies is capable of supporting high-speed communication and high-precision sensing for the upcoming 6G. This paper studies a waveform strategy by designing the orthogonal frequency division multiplexing (OFDM)-based reference signal (RS) for sensing and communication in ISAC system. We derive the closed-form expressions of Cram\'er-Rao Bound (CRB) for the distance and velocity estimations, and obtain the communication rate under the mean square error of channel estimation. Then, a weighted sum CRB minimization problem on the distance and velocity estimations is formulated by considering communication rate requirement and RS intervals constraints, which is a mixed-integer problem due to the discrete RS interval values. To solve this problem, some numerical methods are typically adopted to obtain the optimal solutions, whose computational complexity grow exponentially with the number of symbols and subcarriers of OFDM. Therefore, we propose a relaxation and approximation method to transform the original discrete problem into a continuous convex one and obtain the sub-optimal solutions. Finally, our proposed scheme is compared with the exhaustive search method in numerical simulations, which show slight gap between the obtained sub-optimal and optimal solutions, and this gap further decreases with large weight factor., Comment: 6 pages, 4 figures
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- 2024
21. Instance Performance Difference: A Metric to Measure the Sim-To-Real Gap in Camera Simulation
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Chen, Bo-Hsun and Negrut, Dan
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Computer Science - Robotics - Abstract
In this contribution, we introduce the concept of Instance Performance Difference (IPD), a metric designed to measure the gap in performance that a robotics perception task experiences when working with real vs. synthetic pictures. By pairing synthetic and real instances in the pictures and evaluating their performance similarity using perception algorithms, IPD provides a targeted metric that closely aligns with the needs of real-world applications. We explain and demonstrate this metric through a rock detection task in lunar terrain images, highlighting the IPD's effectiveness in identifying the most realistic image synthesis method. The metric is thus instrumental in creating synthetic image datasets that perform in perception tasks like real-world photo counterparts. In turn, this supports robust sim-to-real transfer for perception algorithms in real-world robotics applications., Comment: 4 pages, 3 figures, 1 table
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- 2024
22. Contextualized Evaluations: Taking the Guesswork Out of Language Model Evaluations
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Malaviya, Chaitanya, Chang, Joseph Chee, Roth, Dan, Iyyer, Mohit, Yatskar, Mark, and Lo, Kyle
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Computer Science - Computation and Language - Abstract
Language model users often issue queries that lack specification, where the context under which a query was issued -- such as the user's identity, the query's intent, and the criteria for a response to be useful -- is not explicit. For instance, a good response to a subjective query like "What book should I read next?" would depend on the user's preferences, and a good response to an open-ended query like "How do antibiotics work against bacteria?" would depend on the user's expertise. This makes evaluation of responses to such queries an ill-posed task, as evaluators may make arbitrary judgments about the response quality. To remedy this, we present contextualized evaluations, a protocol that synthetically constructs context surrounding an underspecified query and provides it during evaluation. We find that the presence of context can 1) alter conclusions drawn from evaluation, even flipping win rates between model pairs, 2) nudge evaluators to make fewer judgments based on surface-level criteria, like style, and 3) provide new insights about model behavior across diverse contexts. Specifically, our procedure uncovers an implicit bias towards WEIRD contexts in models' "default" responses and we find that models are not equally sensitive to following different contexts, even when they are provided in prompts., Comment: Code & data available at https://github.com/allenai/ContextEval
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- 2024
23. Continual Memorization of Factoids in Large Language Models
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Chen, Howard, Geng, Jiayi, Bhaskar, Adithya, Friedman, Dan, and Chen, Danqi
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Computer Science - Computation and Language - Abstract
Large language models can absorb a massive amount of knowledge through pretraining, but pretraining is inefficient for acquiring long-tailed or specialized facts. Therefore, fine-tuning on specialized or new knowledge that reflects changes in the world has become popular, though it risks disrupting the model's original capabilities. We study this fragility in the context of continual memorization, where the model is trained on a small set of long-tail factoids (factual associations) and must retain these factoids after multiple stages of subsequent training on other datasets. Through extensive experiments, we show that LLMs suffer from forgetting across a wide range of subsequent tasks, and simple replay techniques do not fully prevent forgetting, especially when the factoid datasets are trained in the later stages. We posit that there are two ways to alleviate forgetting: 1) protect the memorization process as the model learns the factoids, or 2) reduce interference from training in later stages. With this insight, we develop an effective mitigation strategy: REMIX (Random and Generic Data Mixing). REMIX prevents forgetting by mixing generic data sampled from pretraining corpora or even randomly generated word sequences during each stage, despite being unrelated to the memorized factoids in the first stage. REMIX can recover performance from severe forgetting, often outperforming replay-based methods that have access to the factoids from the first stage. We then analyze how REMIX alters the learning process and find that successful forgetting prevention is associated with a pattern: the model stores factoids in earlier layers than usual and diversifies the set of layers that store these factoids. The efficacy of REMIX invites further investigation into the underlying dynamics of memorization and forgetting, opening exciting possibilities for future research.
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- 2024
24. Hilbert modular Eisenstein congruences of local origin
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Fretwell, Dan and Roberts, Jenny
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Mathematics - Number Theory - Abstract
Let $F$ be an arbitrary totally real field. Under weak conditions we prove the existence of certain Eisenstein congruences between parallel weight $k \geq 3$ Hilbert eigenforms of level $\mathfrak{mp}$ and Hilbert Eisenstein series of level $\mathfrak{m}$, for arbitrary ideal $\mathfrak{m}$ and prime ideal $\mathfrak{p}\nmid \mathfrak{m}$ of $\mathcal{O}_F$. Such congruences have their moduli coming from special values of Hecke $L$-functions and their Euler factors, and our results allow for the eigenforms to have non-trivial Hecke character. After this, we consider the question of when such congruences can be satisfied by newforms, proving a general result about this., Comment: 23 pages
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- 2024
25. Forecast error growth: A dynamic-stochastic model
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Bach, Eviatar, Crisan, Dan, and Ghil, Michael
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Physics - Atmospheric and Oceanic Physics - Abstract
There is a history of simple forecast error growth models designed to capture the key properties of error growth in operational numerical weather prediction (NWP) models. We propose here such a scalar model that relies on the previous ones and incorporates multiplicative noise in a nonlinear stochastic differential equation (SDE). We analyze the properties of the SDE, including the shape of the error growth curve for small times and its stationary distribution, and prove well-posedness and positivity of solutions. We then fit this model to operational NWP error growth curves, showing good agreement with both the mean and probabilistic features of the error growth. These results suggest that the dynamic-stochastic error growth model proposed herein and similar ones could play a role in many other areas of the sciences that involve prediction., Comment: 10 pages, 7 figures
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- 2024
26. CQUESST: A dynamical stochastic framework for predicting soil-carbon sequestration
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Pagendam, Dan, Baldock, Jeff, Clifford, David, Farquharson, Ryan, Murray, Lawrence, Beare, Mike, Curtin, Denis, and Cressie, Noel
- Subjects
Statistics - Applications ,Statistics - Computation - Abstract
A statistical framework we call CQUESST (Carbon Quantification and Uncertainty from Evolutionary Soil STochastics), which models carbon sequestration and cycling in soils, is applied to a long-running agricultural experiment that controls for crop type, tillage, and season. The experiment, known as the Millenium Tillage Trial (MTT), ran on 42 field-plots for ten years from 2000-2010; here CQUESST is used to model soil carbon dynamically in six pools, in each of the 42 agricultural plots, and on a monthly time step for a decade. We show how CQUESST can be used to estimate soil-carbon cycling rates under different treatments. Our methods provide much-needed statistical tools for quantitatively inferring the effectiveness of different experimental treatments on soil-carbon sequestration. The decade-long data are of multiple observation types, and these interacting time series are ingested into a fully Bayesian model that has a dynamic stochastic model of multiple pools of soil carbon at its core. CQUESST's stochastic model is motivated by the deterministic RothC soil-carbon model based on nonlinear difference equations. We demonstrate how CQUESST can estimate soil-carbon fluxes for different experimental treatments while acknowledging uncertainties in soil-carbon dynamics, in physical parameters, and in observations. CQUESST is implemented efficiently in the probabilistic programming language Stan using its MapReduce parallelization, and it scales well for large numbers of field-plots, using software libraries that allow for computation to be shared over multiple nodes of high-performance computing clusters.
- Published
- 2024
27. Snippet-based Conversational Recommender System
- Author
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Sun, Haibo, Otani, Naoki, Kim, Hannah, Zhang, Dan, and Bhutani, Nikita
- Subjects
Computer Science - Information Retrieval - Abstract
Conversational Recommender Systems (CRS) engage users in interactive dialogues to gather preferences and provide personalized recommendations. Traditionally, CRS rely on pre-defined attributes or expensive, domain-specific annotated datasets to guide conversations, which limits flexibility and adaptability across domains. In this work, we introduce SnipRec, a novel CRS that enhances dialogues and recommendations by extracting diverse expressions and preferences from user-generated content (UGC) like customer reviews. Using large language models, SnipRec maps user responses and UGC to concise snippets, which are used to generate clarification questions and retrieve relevant items. Our approach eliminates the need for domain-specific training, making it adaptable to new domains and effective without prior knowledge of user preferences. Extensive experiments on the Yelp dataset demonstrate the effectiveness of snippet-based representations against document and sentence-based representations. Additionally, SnipRec is able to improve Hits@10 by 0.25 over the course of five conversational turns, underscoring the efficiency of SnipRec in capturing user preferences through multi-turn conversations.
- Published
- 2024
28. FactLens: Benchmarking Fine-Grained Fact Verification
- Author
-
Mitra, Kushan, Zhang, Dan, Rahman, Sajjadur, and Hruschka, Estevam
- Subjects
Computer Science - Computation and Language ,Computer Science - Artificial Intelligence ,Computer Science - Machine Learning - Abstract
Large Language Models (LLMs) have shown impressive capability in language generation and understanding, but their tendency to hallucinate and produce factually incorrect information remains a key limitation. To verify LLM-generated contents and claims from other sources, traditional verification approaches often rely on holistic models that assign a single factuality label to complex claims, potentially obscuring nuanced errors. In this paper, we advocate for a shift toward fine-grained verification, where complex claims are broken down into smaller sub-claims for individual verification, allowing for more precise identification of inaccuracies, improved transparency, and reduced ambiguity in evidence retrieval. However, generating sub-claims poses challenges, such as maintaining context and ensuring semantic equivalence with respect to the original claim. We introduce FactLens, a benchmark for evaluating fine-grained fact verification, with metrics and automated evaluators of sub-claim quality. The benchmark data is manually curated to ensure high-quality ground truth. Our results show alignment between automated FactLens evaluators and human judgments, and we discuss the impact of sub-claim characteristics on the overall verification performance., Comment: 12 pages, under review
- Published
- 2024
29. New methods of neutrino and anti-neutrino detection from 0.115 to 105 MeV
- Author
-
Solomey, Nickolas, Christl, Mark, Doty, Brian, Folkerts, Jonathan, Hartsock, Brooks, Kuznetsco, Evgen, McTaggart, Robert, Meyer, Holger, Nolan, Tyler, Pawloski, Greg, Reichart, Daniel, Rodriguez-Otero, Miguel, Smith, Dan, and Solomey, Lisa
- Subjects
Physics - Instrumentation and Detectors ,High Energy Physics - Experiment ,Nuclear Experiment - Abstract
We have developed a neutrino detector with threshold energies from ~0.115 to 105 MeV in a clean detection mode almost completely void of accidental backgrounds. It was initially developed for the NASA $\nu$SOL project to put a solar neutrino detector very close to the Sun with 1,000 to 10,000 times higher solar neutrino flux than on Earth. Similar interactions have been found for anti-neutrinos, which were initially intended for Beta decay neutrinos from reactors, geological sources, or for nuclear security applications. These techniques work at the 1 to 100 MeV region for neutrinos from the ORNL Spallation Neutron Source or low energy accelerator neutrino and anti-neutrino production targets less than $\sim$100 MeV. The identification process is clean, with a double pulse detection signature within a time window between the first interaction producing the conversion electron or positron and the secondary gamma emission 100 ns to ~1 $\mu$s, which removes most accidental backgrounds. These new modes for neutrino and anti-neutrino detection of low energy neutrinos and anti-neutrinos could allow improvements to neutrino interaction measurements from an accelerator beam on a target., Comment: Contribution to the 25th International Workshop on Neutrinos from Accelerators
- Published
- 2024
30. Pathwise Optimal Control and Rough Fractional Hamilton-Jacobi-Bellman Equations for Rough-Fractional Dynamics
- Author
-
Iannucci, Andrea, Crisan, Dan, and Cass, Thomas
- Subjects
Mathematics - Optimization and Control - Abstract
We use a rough path-based approach to investigate the degeneracy problem in the context of pathwise control. We extend the framework developed in arXiv:1902.05434 to treat admissible controls from a suitable class of H\"older continuous paths and simultaneously to handle a broader class of noise terms. Our approach uses fractional calculus to augment the original control equation, resulting in a system with added fractional dynamics. We adapt the existing analysis of fractional systems from the work of Gomoyunov arXiv:1908.01747, arXiv:2111.14400v1 , arXiv:2109.02451 to this new setting, providing a notion of a rough fractional viscosity solution for fractional systems that involve a noise term of arbitrarily low regularity. In this framework, following the method outlined in arXiv:1902.05434, we derive sufficient conditions to ensure that the control problem remains non-degenerate.
- Published
- 2024
31. Dynamic-Attention-based EEG State Transition Modeling for Emotion Recognition
- Author
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Shen, Xinke, Gan, Runmin, Wang, Kaixuan, Yang, Shuyi, Zhang, Qingzhu, Liu, Quanying, Zhang, Dan, and Song, Sen
- Subjects
Computer Science - Human-Computer Interaction ,Electrical Engineering and Systems Science - Signal Processing ,Quantitative Biology - Neurons and Cognition - Abstract
Electroencephalogram (EEG)-based emotion decoding can objectively quantify people's emotional state and has broad application prospects in human-computer interaction and early detection of emotional disorders. Recently emerging deep learning architectures have significantly improved the performance of EEG emotion decoding. However, existing methods still fall short of fully capturing the complex spatiotemporal dynamics of neural signals, which are crucial for representing emotion processing. This study proposes a Dynamic-Attention-based EEG State Transition (DAEST) modeling method to characterize EEG spatiotemporal dynamics. The model extracts spatiotemporal components of EEG that represent multiple parallel neural processes and estimates dynamic attention weights on these components to capture transitions in brain states. The model is optimized within a contrastive learning framework for cross-subject emotion recognition. The proposed method achieved state-of-the-art performance on three publicly available datasets: FACED, SEED, and SEED-V. It achieved 75.4% accuracy in the binary classification of positive and negative emotions and 59.3% in nine-class discrete emotion classification on the FACED dataset, 88.1% in the three-class classification of positive, negative, and neutral emotions on the SEED dataset, and 73.6% in five-class discrete emotion classification on the SEED-V dataset. The learned EEG spatiotemporal patterns and dynamic transition properties offer valuable insights into neural dynamics underlying emotion processing., Comment: 14 pages, 6 figures
- Published
- 2024
32. Galaxy Mergers in the Epoch of Reionization II: Major Merger-Triggered Star Formation and AGN Activities at $z = 4.5 - 8.5$
- Author
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Duan, Qiao, Li, Qiong, Conselice, Christopher J., Harvey, Thomas, Austin, Duncan, Adams, Nathan J., Ferreira, Leonardo, Duncan, Kenneth J., Trussler, James, Pascalau, Robert G., Windhorst, Rogier A., Holwerda, Benne W., Broadhurst, Thomas J., Coe, Dan, Cohen, Seth H., Du, Xiaojing, Driver, Simon P., Frye, Brenda, Grogin, Norman A., Hathi, Nimish P., Jansen, Rolf A., Koekemoer, Anton M., Marshall, Madeline A., Nonino, Mario, Ortiz III, Rafael, Pirzkal, Nor, Robotham, Aaron, Ryan Jr, Russell E., Summers, Jake, D'Silva, Jordan C. J., Willmer, Christopher N. A., and Yan, Haojing
- Subjects
Astrophysics - Astrophysics of Galaxies - Abstract
Galaxy mergers are a key driver of galaxy formation and evolution, including the triggering of AGN and star formation to a still unknown degree. We thus investigate the impact of galaxy mergers on star formation and AGN activity using a sample of 3,330 galaxies at $z = [4.5, 8.5]$ from eight JWST fields (CEERS, JADES GOODS-S, NEP-TDF, NGDEEP, GLASS, El-Gordo, SMACS-0723, and MACS-0416), collectively covering an unmasked area of 189 arcmin$^2$. We focuses on star formation rate (SFR) enhancement, AGN fraction, and AGN excess in major merger ($\mu > 1/4$) close-pair samples, defined by $\Delta z < 0.3$ and projected separations $r_p < 100$ kpc, compared to non-merger samples. We find that SFR enhancement occurs only at $r_p < 20$ kpc, with values of $0.25 \pm 0.10$ dex and $0.26 \pm 0.11$ dex above the non-merger medians for $z = [4.5, 6.5]$ and $z = [6.5, 8.5]$, respectively. No other statistically significant enhancements in galaxy sSFR or stellar mass are observed at any projected separation or redshift bin. We also compare our observational results with predictions from the SC-SAM simulation and find no evidence of star formation enhancement in the simulations at any separation range. Finally, we examine the AGN fraction and AGN excess, finding that the fraction of AGNs in AGN-galaxy pairs, relative to the total AGN population, is $3.25^{+1.50}_{-1.06}$ times greater than the fraction of galaxy pairs relative to the overall galaxy population at the same redshift. We find that nearly all AGNs have a companion within 100 kpc and observe an excess AGN fraction in close-pair samples compared to non-merger samples. This excess is found to be $1.26 \pm 0.06$ and $1.34 \pm 0.06$ for AGNs identified via the inferred BPT diagram and photometric SED selection, respectively., Comment: 17 Pages, 7 Figures, Submitted to MNRAS
- Published
- 2024
33. Rubin ToO 2024: Envisioning the Vera C. Rubin Observatory LSST Target of Opportunity program
- Author
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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
- Subjects
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.
- Published
- 2024
34. Qutrit Toric Code and Parafermions in Trapped Ions
- Author
-
Iqbal, Mohsin, Lyons, Anasuya, Lo, Chiu Fan Bowen, Tantivasadakarn, Nathanan, Dreiling, Joan, Foltz, Cameron, Gatterman, Thomas M., Gresh, Dan, Hewitt, Nathan, Holliman, Craig A., Johansen, Jacob, Neyenhuis, Brian, Matsuoka, Yohei, Mills, Michael, Moses, Steven A., Siegfried, Peter, Vishwanath, Ashvin, Verresen, Ruben, and Dreyer, Henrik
- Subjects
Quantum Physics ,Condensed Matter - Strongly Correlated Electrons - Abstract
The development of programmable quantum devices can be measured by the complexity of manybody states that they are able to prepare. Among the most significant are topologically ordered states of matter, which enable robust quantum information storage and processing. While topological orders are more readily accessible with qudits, experimental realisations have thus far been limited to lattice models of qubits. Here, we prepare a ground state of the Z3 toric code state on 24 qutrits in a trapped ion quantum processor with fidelity per qutrit exceeding 96.5(3)%. We manipulate two types of defects which go beyond the conventional qubit toric code: a parafermion, and its bound state which is related to charge conjugation symmetry. We further demonstrate defect fusion and the transfer of entanglement between anyons and defects, which we use to control topological qutrits. Our work opens up the space of long-range entangled states with qudit degrees of freedom for use in quantum simulation and universal error-correcting codes., Comment: 8+20 pages, 15 figures
- Published
- 2024
35. Retentive Neural Quantum States: Efficient Ans\'atze for Ab Initio Quantum Chemistry
- Author
-
Knitter, Oliver, Zhao, Dan, Stokes, James, Ganahl, Martin, Leichenauer, Stefan, and Veerapaneni, Shravan
- Subjects
Computer Science - Machine Learning ,Computer Science - Computational Engineering, Finance, and Science ,Quantum Physics - Abstract
Neural-network quantum states (NQS) has emerged as a powerful application of quantum-inspired deep learning for variational Monte Carlo methods, offering a competitive alternative to existing techniques for identifying ground states of quantum problems. A significant advancement toward improving the practical scalability of NQS has been the incorporation of autoregressive models, most recently transformers, as variational ansatze. Transformers learn sequence information with greater expressiveness than recurrent models, but at the cost of increased time complexity with respect to sequence length. We explore the use of the retentive network (RetNet), a recurrent alternative to transformers, as an ansatz for solving electronic ground state problems in $\textit{ab initio}$ quantum chemistry. Unlike transformers, RetNets overcome this time complexity bottleneck by processing data in parallel during training, and recurrently during inference. We give a simple computational cost estimate of the RetNet and directly compare it with similar estimates for transformers, establishing a clear threshold ratio of problem-to-model size past which the RetNet's time complexity outperforms that of the transformer. Though this efficiency can comes at the expense of decreased expressiveness relative to the transformer, we overcome this gap through training strategies that leverage the autoregressive structure of the model -- namely, variational neural annealing. Our findings support the RetNet as a means of improving the time complexity of NQS without sacrificing accuracy. We provide further evidence that the ablative improvements of neural annealing extend beyond the RetNet architecture, suggesting it would serve as an effective general training strategy for autoregressive NQS., Comment: 16 pages, 1 figure, to be submitted for peer-reviewed publication
- Published
- 2024
36. An Ordinary Differential Equation Framework for Stability Analysis of Networks with Finite Buffers
- Author
-
Wu, Xinyu, Wu, Dan, and Modiano, Eytan
- Subjects
Computer Science - Networking and Internet Architecture - Abstract
We consider the problem of network stability in finite-buffer systems. We observe that finite buffer may affect stability even in simplest network structure, and we propose an ordinary differential equation (ODE) model to capture the queuing dynamics and analyze the stability in buffered communication networks with general topology. For single-commodity systems, we propose a sufficient condition, which follows the fundamental idea of backpressure, for local transmission policies to stabilize the networks based on ODE stability theory. We further extend the condition to multi-commodity systems, with an additional restriction on the coupling level between different commodities, which can model networks with per-commodity buffers and shared buffers. The framework characterizes a set of policies that can stabilize buffered networks, and is useful for analyzing the effect of finite buffers on network stability.
- Published
- 2024
37. Towards pandemic preparedness: ability to estimate high-resolution social contact patterns from longitudinal surveys
- Author
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Dan, Shozen, Tegegne, Joshua, Chen, Yu, Ling, Zhi, Jaeger, Veronika K., Karch, André, Mishra, Swapnil, and Ratmann, Oliver
- Subjects
Statistics - Applications - Abstract
Social contact surveys are an important tool to assess infection risks within populations, and the effect of non-pharmaceutical interventions on social behaviour during disease outbreaks, epidemics, and pandemics. Numerous longitudinal social contact surveys were conducted during the COVID-19 era, however data analysis is plagued by reporting fatigue, a phenomenon whereby the average number of social contacts reported declines with the number of repeat participations and as participants' engagement decreases over time. Using data from the German COVIMOD Study between April 2020 to December 2021, we demonstrate that reporting fatigue varied considerably by sociodemographic factors and was consistently strongest among parents reporting children contacts (parental proxy reporting), students, middle-aged individuals, those in full-time employment and those self-employed. We find further that, when using data from first-time participants as gold standard, statistical models incorporating a simple logistic function to control for reporting fatigue were associated with substantially improved estimation accuracy relative to models with no reporting fatigue adjustments, and that no cap on the number of repeat participations was required. These results indicate that existing longitudinal contact survey data can be meaningfully interpreted under an easy-to-implement statistical approach adressing reporting fatigue confounding, and that longitudinal designs including repeat participants are a viable option for future social contact survey designs.
- Published
- 2024
38. Phase transition on superfluid vortices in Higgs-Confinement crossover
- Author
-
Hayata, Tomoya, Hidaka, Yoshimasa, and Kondo, Dan
- Subjects
High Energy Physics - Theory ,Condensed Matter - Superconductivity ,High Energy Physics - Lattice ,High Energy Physics - Phenomenology ,Nuclear Theory - Abstract
We propose a novel method to distinguish states of matter by identifying spontaneous symmetry breaking on extended objects, such as vortices, even in the absence of a bulk phase transition. As a specific example, we investigate the phase transition on superfluid vortices in the Higgs-confinement crossover using a $\mathrm{U}(1)_\mathrm{gauge} \times \mathrm{U}(1)_\mathrm{global}$ model. This model exhibits superfluidity of $\mathrm{U}(1)_\mathrm{global}$ symmetry and allows for a crossover between the Higgs and confinement regimes by varying the gauge coupling constant from weak to strong. We demonstrate that, on vortices, spontaneous breaking of the $\mathbb{Z}_2$ flavor symmetry occurs in the weak coupling (Higgs) regime, while it does not in the strong coupling (confinement) regime. We also confirm that those regimes are separated by a second-order phase transition through Monte Carlo simulations, whose universality class corresponds to the two-dimensional Ising model., Comment: 22 pages, 5 figures
- Published
- 2024
39. SurfGNN: A robust surface-based prediction model with interpretability for coactivation maps of spatial and cortical features
- Author
-
Li, Zhuoshuo, Zhang, Jiong, Zeng, Youbing, Lin, Jiaying, Zhang, Dan, Zhang, Jianjia, Xu, Duan, Kim, Hosung, Liu, Bingguang, and Liu, Mengting
- Subjects
Quantitative Biology - Neurons and Cognition ,Computer Science - Artificial Intelligence ,Computer Science - Computer Vision and Pattern Recognition ,J.3 - Abstract
Current brain surface-based prediction models often overlook the variability of regional attributes at the cortical feature level. While graph neural networks (GNNs) excel at capturing regional differences, they encounter challenges when dealing with complex, high-density graph structures. In this work, we consider the cortical surface mesh as a sparse graph and propose an interpretable prediction model-Surface Graph Neural Network (SurfGNN). SurfGNN employs topology-sampling learning (TSL) and region-specific learning (RSL) structures to manage individual cortical features at both lower and higher scales of the surface mesh, effectively tackling the challenges posed by the overly abundant mesh nodes and addressing the issue of heterogeneity in cortical regions. Building on this, a novel score-weighted fusion (SWF) method is implemented to merge nodal representations associated with each cortical feature for prediction. We apply our model to a neonatal brain age prediction task using a dataset of harmonized MR images from 481 subjects (503 scans). SurfGNN outperforms all existing state-of-the-art methods, demonstrating an improvement of at least 9.0% and achieving a mean absolute error (MAE) of 0.827+0.056 in postmenstrual weeks. Furthermore, it generates feature-level activation maps, indicating its capability to identify robust regional variations in different morphometric contributions for prediction., Comment: 15 pages, 6 figures
- Published
- 2024
40. Enhancing Transformer Training Efficiency with Dynamic Dropout
- Author
-
Yan, Hanrui and Shao, Dan
- Subjects
Computer Science - Machine Learning - Abstract
We introduce Dynamic Dropout, a novel regularization technique designed to enhance the training efficiency of Transformer models by dynamically adjusting the dropout rate based on training epochs or validation loss improvements. This approach addresses the challenge of balancing regularization and model capacity, which is crucial for achieving fast convergence and high performance. Our method involves modifying the GPT model to accept a variable dropout rate and updating dropout layers during training using schedules such as linear decay, exponential decay, and validation loss-based adjustments. Extensive experiments on the Shakespeare\_char dataset demonstrate that Dynamic Dropout significantly accelerates training and improves inference efficiency compared to a baseline model with a fixed dropout rate. The validation loss-based adjustment schedule provided the best overall performance, highlighting the potential of Dynamic Dropout as a valuable technique for training large-scale Transformer models.
- Published
- 2024
41. Potential signature of new magicity from universal aspects of nuclear charge radii
- Author
-
Yang, Dan, Rong, Yu-Ting, An, Rong, and Shi, Rui-Xiang
- Subjects
Nuclear Theory - Abstract
Shell quenching phenomena in nuclear charge radii are typically observed at the well-established neutron magic numbers. However, the recent discovery of potential new magic numbers at the neutron numbers $N = 32$ and $N = 34$ has sparked renewed interest in this mass region. This work further inspects into the charge radii of nuclei around the $N = 28$ shell closure using the relativistic Hartree-Bogoliubov model. We incorporate meson exchange and point-coupling effective nucleon-nucleon interactions alongside the Bogoliubov transformation for pairing corrections. To accurately capture the odd-even staggering and shell closure effects observed in charge radii, neutron-proton correlations around Fermi surface are explicitly considered. The charge radii of Ca and Ni isotopes are used to test the theoretical model and show an improvement with neutron-proton pairing corrections, in particular for neutron-rich isotopes. Our calculations reveal a inverted parabolic-like trend in the charge radii along the $N = 28$ isotones for proton numbers $Z$ between 20 and 28. Additionally, the shell closure effect of $Z = 28$ persists across the $N = 28$, 30, 32, and 34 isotonic chains, albeit with a gradual weakening trend. Notably, the significantly abrupt changes in charge radii are observed across $Z = 22$ along both the $N = 32$ and $N = 34$ isotonic chains. This kink at $Z = 22$ comes from the sudden decrease of the neuron-proton correlation around Fermi surfaces across $Z = 22$ for $N = 30$, 32, and 34 isotones, and might provide a signature for identifying the emergence of neutron magic numbers $N = 32$ and 34. Furthermore, the calculated charge radii for these isotonic chains ($N = 28$, 30, 32, and 34) can serve as reliable guidelines for future experimental measurements.
- Published
- 2024
42. Tetrahedral shape and Lambda impurity effect in $^{80}$Zr with a multidimensionally constrained relativistic Hartree-Bogoliubov model
- Author
-
Yang, Dan and Rong, Yu-Ting
- Subjects
Nuclear Theory - Abstract
This study investigates the tetrahedral structure in $^{80}$Zr and Lambda ($\Lambda$) impurity effect in $^{81}_{~\Lambda}$Zr using the multidimensionally constrained relativistic Hartree-Bogoliubov model. The ground states of both $^{80}$Zr and $^{81}_{~\Lambda}$Zr exhibit a tetrahedral configuration, accompanied by prolate and axial-octupole shape isomers. Our calculations reveal there are changes in the deformation parameters $\beta_{20}$, $\beta_{30}$, and $\beta_{32}$ upon $\Lambda$ binding to $^{80}$Zr, except for $\beta_{32}$ when $\Lambda$ occupies $p$-orbits. Compared to the two shape isomers, the $\Lambda$ particle exhibits weaker binding energy in the tetrahedral state when occupying the $1/2^+[000](\Lambda_s)$ or $1/2^-[110]$ single-particle states. In contrast, the strongest binding occurs for the $\Lambda$ particle in the $1/2^-[101]$ state with tetrahedral shape. Besides, a large $\Lambda$ separation energy may not necessarily correlate with a significant overlap between the density distributions of the $\Lambda$ particle and the nuclear core, particularly for tetrahedral hypernuclei.
- Published
- 2024
43. AtlasSeg: Atlas Prior Guided Dual-U-Net for Cortical Segmentation in Fetal Brain MRI
- Author
-
Xu, Haoan, Zheng, Tianshu, Xu, Xinyi, Shen, Yao, Sun, Jiwei, Sun, Cong, Wang, Guangbin, and Wu, Dan
- Subjects
Electrical Engineering and Systems Science - Image and Video Processing ,Computer Science - Artificial Intelligence ,Computer Science - Computer Vision and Pattern Recognition - Abstract
Accurate tissue segmentation in fetal brain MRI remains challenging due to the dynamically changing anatomical anatomy and contrast during fetal development. To enhance segmentation accuracy throughout gestation, we introduced AtlasSeg, a dual-U-shape convolution network incorporating gestational age (GA) specific information as guidance. By providing a publicly available fetal brain atlas with segmentation label at the corresponding GA, AtlasSeg effectively extracted the contextual features of age-specific patterns in atlas branch and generated tissue segmentation in segmentation branch. Multi-scale attentive atlas feature fusions were constructed in all stages during encoding and decoding, giving rise to a dual-U-shape network to assist feature flow and information interactions between two branches. AtlasSeg outperformed six well-known segmentation networks in both our internal fetal brain MRI dataset and the external FeTA dataset. Ablation experiments demonstrate the efficiency of atlas guidance and the attention mechanism. The proposed AtlasSeg demonstrated superior segmentation performance against other convolution networks with higher segmentation accuracy, and may facilitate fetal brain MRI analysis in large-scale fetal brain studies.
- Published
- 2024
44. Short-maturity options on realized variance in local-stochastic volatility models
- Author
-
Pirjol, Dan, Wang, Xiaoyu, and Zhu, Lingjiong
- Subjects
Quantitative Finance - Pricing of Securities - Abstract
We derive the short-maturity asymptotics for prices of options on realized variance in local-stochastic volatility models. We consider separately the short-maturity asymptotics for out-of-the-money and in-the-money options cases. The analysis for the out-of-the-money case uses large deviations theory and the solution for the rate function involves solving a two-dimensional variational problem. In the special case when the Brownian noises in the asset price dynamics and the volatility process are uncorrelated, we solve this variational problem explicitly. For the correlated case, we obtain upper and lower bounds for the rate function, as well as an expansion around the at-the-money point. Numerical simulations of the prices of variance options in a local-stochastic volatility model with bounded local volatility are in good agreement with the asymptotic results for sufficiently small maturity. The leading-order asymptotics for at-the-money options on realized variance is dominated by fluctuations of the asset price around the spot value, and is computed in closed form., Comment: 46 pages, 2 figures, 1 table
- Published
- 2024
45. LHC EFT WG Note: Basis for Anomalous Quartic Gauge Couplings
- Author
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Durieux, Gauthier, Remmen, Grant N., Rodd, Nicholas L., Éboli, O. J. P., Gonzalez-Garcia, M. C., Kondo, Dan, Murayama, Hitoshi, and Okabe, Risshin
- Subjects
High Energy Physics - Phenomenology ,High Energy Physics - Experiment ,High Energy Physics - Theory - Abstract
In this note, we give a definitive basis for the dimension-eight operators leading to quartic -- but no cubic -- interactions among electroweak gauge bosons. These are often called anomalous quartic gauge couplings, or aQGCs. We distinguish in particular the CP-even ones from their CP-odd counterparts., Comment: LHC Effective Field Theory Working Group Note, 8 pages, 3 tables
- Published
- 2024
46. 'Give Me BF16 or Give Me Death'? Accuracy-Performance Trade-Offs in LLM Quantization
- Author
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Kurtic, Eldar, Marques, Alexandre, Pandit, Shubhra, Kurtz, Mark, and Alistarh, Dan
- Subjects
Computer Science - Machine Learning ,Computer Science - Artificial Intelligence - Abstract
Despite the popularity of large language model (LLM) quantization for inference acceleration, significant uncertainty remains regarding the accuracy-performance trade-offs associated with various quantization formats. We present a comprehensive empirical study of quantized accuracy, evaluating popular quantization formats (FP8, INT8, INT4) across academic benchmarks and real-world tasks, on the entire Llama-3.1 model family. Additionally, our study examines the difference in text generated by quantized models versus their uncompressed counterparts. Beyond benchmarks, we also present a couple of quantization improvements which allowed us to obtain state-of-the-art accuracy recovery results. Our investigation, encompassing over 500,000 individual evaluations, yields several key findings: (1) FP8 weight and activation quantization (W8A8-FP) is lossless across all model scales, (2) INT8 weight and activation quantization (W8A8-INT), when properly tuned, incurs surprisingly low 1-3% accuracy degradation, and (3) INT4 weight-only quantization (W4A16-INT) is competitive with 8-bit integer weight and activation quantization. To address the question of the "best" format for a given deployment environment, we conduct inference performance analysis using the popular open-source vLLM framework on various GPU architectures. We find that W4A16 offers the best cost-efficiency for synchronous deployments, and for asynchronous deployment on mid-tier GPUs. At the same time, W8A8 formats excel in asynchronous "continuous batching" deployment of mid- and large-size models on high-end GPUs. Our results provide a set of practical guidelines for deploying quantized LLMs across scales and performance requirements.
- Published
- 2024
47. GaAs doped by self-assembled molecular monolayers
- Author
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Fan, Zhengfang, Liu, Yumeng, Wang, Yizuo, Guo, Shuwen, He, Li, and Dan, Yaping
- Subjects
Condensed Matter - Materials Science ,Condensed Matter - Mesoscale and Nanoscale Physics - Abstract
Self-assembled molecular monolayer doping remains as a research focus for its nature of being conformal, nondestructive, and self-limiting. Herein, we demonstrate a sulfur monolayer doping in GaAs, facilitated by (NH4)2Sx solution. The Van der Pauw technique, secondary-ion mass spectroscopy, and low-temperature Hall effect measurements show that the sulfur dopants concentration and electron activation rate are 4*10^20 cm-3 and 77.6%, respectively. The donor energy level of sulfur-doped GaAs is located 68 meV below the conduction band. Based on this process, a p-n junction was successfully fabricated on highly doped p-type GaAs substrate., Comment: 13pages, 5figures
- Published
- 2024
48. Defects in graphite engineered by ion implantation for the self-assembly of gold nanoparticles
- Author
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Liu, Yumeng, Deng, Yanhao, Wang, Yizhuo, Wang, Li, Liu, Tong, Wei, Wei, Gong, Zhongmiao, Fan, Zhengfang, Su, Zhijuan, Wang, Yanming, and Dan, Yaping
- Subjects
Condensed Matter - Materials Science ,Condensed Matter - Mesoscale and Nanoscale Physics - Abstract
Defect engineering in two-dimensional (2D) materials is essential for advancing applications such as gas sensing, single-atom catalysis, and guided nanoparticle self-assembly, enabling the creation of materials with tailored functionalities. This study investigates ion implantation effects on highly ordered pyrolytic graphite (HOPG) surfaces, using scanning tunneling microscopy (STM) and density functional theory (DFT) simulations to identify distinct defect structures. High-energy heavy ions cause inelastic scattering, increasing surface damage, while gold atoms deposited onto defect sites preferentially form atomic clusters. Through focused ion beam techniques, spatially distributed defects were engineered, guiding the self-assembly of nanoparticles. This research highlights the precision of ion irradiation for modifying HOPG surfaces, with significant implications for catalysis, nanotechnology, and the development of functional materials with controlled nanoscale properties., Comment: 16pages, 6figures
- Published
- 2024
49. Reproducible Monolayer MoS2 Devices Free of Resist Contamination by Gold Mask Lithography
- Author
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Liu, Yumeng, Wang, Yizhuo, Fan, Zhengfang, Wei, Jianyong, Guo, Shuwen, Su, Zhijuan, and Dan, Yaping
- Subjects
Condensed Matter - Materials Science ,Condensed Matter - Mesoscale and Nanoscale Physics - Abstract
Atomically thin MoS2 is a promising material for field-effect transistors (FETs) and electronic devices. However, traditional photolithographic processes introduce surface contamination to 2D materials, leading to poor electrical contacts when metals are deposited. In this work, we present a novel fabrication method using gold as a mask for patterning and etching, which protects 2D materials from contamination in the metal contact region. This technique enabled the fabrication of monolayer MoS2 transistors with clean gold contacts. Additionally, we achieved MoS2 devices with Ohmic contacts, mass-produced traditional lithography and gold mask lithography devices (100 of each), with the latter having a much higher current statistical variance than the former, which demonstrated the effectiveness of this method for contamination-free 2D transistors and potential applications in integrated circuits, Comment: 10pages, 3figures
- Published
- 2024
50. Do Advanced Language Models Eliminate the Need for Prompt Engineering in Software Engineering?
- Author
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Wang, Guoqing, Sun, Zeyu, Gong, Zhihao, Ye, Sixiang, Chen, Yizhou, Zhao, Yifan, Liang, Qingyuan, and Hao, Dan
- Subjects
Computer Science - Software Engineering - Abstract
Large Language Models (LLMs) have significantly advanced software engineering (SE) tasks, with prompt engineering techniques enhancing their performance in code-related areas. However, the rapid development of foundational LLMs such as the non-reasoning model GPT-4o and the reasoning model o1 raises questions about the continued effectiveness of these prompt engineering techniques. This paper presents an extensive empirical study that reevaluates various prompt engineering techniques within the context of these advanced LLMs. Focusing on three representative SE tasks, i.e., code generation, code translation, and code summarization, we assess whether prompt engineering techniques still yield improvements with advanced models, the actual effectiveness of reasoning models compared to non-reasoning models, and whether the benefits of using these advanced models justify their increased costs. Our findings reveal that prompt engineering techniques developed for earlier LLMs may provide diminished benefits or even hinder performance when applied to advanced models. In reasoning LLMs, the ability of sophisticated built-in reasoning reduces the impact of complex prompts, sometimes making simple zero-shot prompting more effective. Furthermore, while reasoning models outperform non-reasoning models in tasks requiring complex reasoning, they offer minimal advantages in tasks that do not need reasoning and may incur unnecessary costs. Based on our study, we provide practical guidance for practitioners on selecting appropriate prompt engineering techniques and foundational LLMs, considering factors such as task requirements, operational costs, and environmental impact. Our work contributes to a deeper understanding of effectively harnessing advanced LLMs in SE tasks, informing future research and application development.
- Published
- 2024
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