40,202 results on '"Seth, P"'
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2. Do Grow-Your-Own Programs Work? Evidence from the Teacher Academy of Maryland. EdWorkingPaper No. 24-958
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Annenberg Institute for School Reform at Brown University, David Blazar, Wenjing Gao, Seth Gershenson, Ramon Goings, and Francisco Lagos
- Abstract
Local teacher recruitment through "grow-your-own" programs is a prominent strategy to address workforce shortages and ensure that incoming teachers resemble, understand, and have strong connections to their communities. We exploit the staggered rollout of the Teacher Academy of Maryland career and technical education certificate program across public high schools, finding that exposed students were more likely to become teachers by 0.6 percentage points (pp), or 47%. Effects are concentrated among White girls (1.4pp/39%) and Black girls (0.7pp/80%). We also identify positive impacts on wages (5% on average/18% for Black girls), countering a prevailing narrative that teaching leaves one worse off financially relative to other labor market opportunities.
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- 2024
3. The Future of Math Inclusion: The Promise of Digital Math Tools for Universally Accessible Mathematics Instruction
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Digital Promise, Lauren Hickman McMahon, Stefani Pautz Stephenson, and Seth Corrigan
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In this report, we share insights from a Research-Practice-Industry Partnership (RPIP) that explored mathematics instructional practices with support of digital mathematics tools. RPIPs bring together researchers, practitioners, and product developers, with each party having an equal voice, in a rapid-cycle model for edtech research and development. We framed this RPIP using the principles of Universal Design for Learning (UDL): provide multiple means of Engagement, Representation, and Action & Expression. These principles support learner variability, improve accessibility, and are closely aligned with mathematics education research, which highlights the multimodal nature of mathematics and the need to use and connect multiple representations to help students develop understanding of mathematics concepts. [This report was produced in partnership with Creativity Labs with funding support from Texthelp.]
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- 2024
4. Disparate Pathways: Understanding Racial Disparities in Teaching. EdWorkingPaper No. 24-945
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Annenberg Institute for School Reform at Brown University, David Blazar, Ramon Goings, Max Anthenelli, Seth Gershenson, and Wenjing Gao
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Mounting evidence supporting the advantages of a diverse teacher workforce prompts policymakers to scrutinize existing recruitment pathways. Following four cohorts of Maryland public high-school students over 12 years reveals several insights. Early barriers require timely interventions, aiding students of color in achieving educational milestones that are prerequisites for teacher candidacy (high school graduation, college enrollment). While alternative pathways that bypass traditional undergraduate teacher preparation may help, current approaches still show persistent racial disparities. Data simulations underscore the need for race-conscious policies specifically targeting or differentially benefiting students of color, as race-neutral strategies have minimal impact. Ultimately, multiple race-conscious policy solutions addressing various educational milestones must demonstrate significant effects--approximately 30% increases--to reshape the teacher workforce to align with student body demographics.
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- 2024
5. Balancing the Scales: Enhancing Fairness in Facial Expression Recognition with Latent Alignment
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Rizvi, Syed Sameen Ahmad, Seth, Aryan, and Narang, Pratik
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Computer Science - Computer Vision and Pattern Recognition ,Computer Science - Machine Learning - Abstract
Automatically recognizing emotional intent using facial expression has been a thoroughly investigated topic in the realm of computer vision. Facial Expression Recognition (FER), being a supervised learning task, relies heavily on substantially large data exemplifying various socio-cultural demographic attributes. Over the past decade, several real-world in-the-wild FER datasets that have been proposed were collected through crowd-sourcing or web-scraping. However, most of these practically used datasets employ a manual annotation methodology for labeling emotional intent, which inherently propagates individual demographic biases. Moreover, these datasets also lack an equitable representation of various socio-cultural demographic groups, thereby inducing a class imbalance. Bias analysis and its mitigation have been investigated across multiple domains and problem settings, however, in the FER domain, this is a relatively lesser explored area. This work leverages representation learning based on latent spaces to mitigate bias in facial expression recognition systems, thereby enhancing a deep learning model's fairness and overall accuracy.
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- 2024
6. KAHANI: Culturally-Nuanced Visual Storytelling Pipeline for Non-Western Cultures
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Hamna, Sudharsan, Deepthi, Seth, Agrima, Budhiraja, Ritvik, Khullar, Deepika, Jain, Vyshak, Bali, Kalika, Vashistha, Aditya, and Segal, Sameer
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Computer Science - Computation and Language - Abstract
Large Language Models (LLMs) and Text-To-Image (T2I) models have demonstrated the ability to generate compelling text and visual stories. However, their outputs are predominantly aligned with the sensibilities of the Global North, often resulting in an outsider's gaze on other cultures. As a result, non-Western communities have to put extra effort into generating culturally specific stories. To address this challenge, we developed a visual storytelling pipeline called KAHANI that generates culturally grounded visual stories for non-Western cultures. Our pipeline leverages off-the-shelf models GPT-4 Turbo and Stable Diffusion XL (SDXL). By using Chain of Thought (CoT) and T2I prompting techniques, we capture the cultural context from user's prompt and generate vivid descriptions of the characters and scene compositions. To evaluate the effectiveness of KAHANI, we conducted a comparative user study with ChatGPT-4 (with DALL-E3) in which participants from different regions of India compared the cultural relevance of stories generated by the two tools. Results from the qualitative and quantitative analysis performed on the user study showed that KAHANI was able to capture and incorporate more Culturally Specific Items (CSIs) compared to ChatGPT-4. In terms of both its cultural competence and visual story generation quality, our pipeline outperformed ChatGPT-4 in 27 out of the 36 comparisons., Comment: Under review
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- 2024
7. The Formation of Black Holes in Non-interacting, Isolated Binaries. Gaia Black Holes as Calibrators of Stellar Winds From Massive Stars
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Kruckow, Matthias U., Andrews, Jeff J., Fragos, Tassos, Holl, Berry, Bavera, Simone S., Briel, Max, Gossage, Seth, Kovlakas, Konstantinos, Rocha, Kyle A., Sun, Meng, Srivastava, Philipp M., Xing, Zepei, and Zapartas, Emmanouil
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Astrophysics - Solar and Stellar Astrophysics ,Astrophysics - Astrophysics of Galaxies - Abstract
Context. The black holes discovered using Gaia, especially Gaia BH1 and BH2, have low mass companions of solar-like metallicity in wide orbits. For standard isolated binary evolution formation channels including interactions such an extreme mass ratio is unexpected; especially in orbits of hundreds to thousands of days. Aims. Here, we investigate a non-interacting formation path for isolated binaries to explain the formation of Gaia BH1 and BH2. Methods. We use single star models computed with MESA to constrain the main characteristics of possible progenitors of long-period black hole binaries like Gaia BH1 and BH2. Then, we incorporate these model grids into the binary population synthesis code POSYDON, to explore whether the formation of the observed binaries at solar metallicity is indeed possible. Results. We find that winds of massive stars ($\gtrsim 80\,M_\odot$), especially during the Wolf-Rayet phase, tend to cause a plateau in the initial stellar mass to final black hole mass relation (at about $13\,M_\odot$ in our default wind prescription). However, stellar winds at earlier evolutionary phases are also important at high metallicity, as they prevent the most massive stars from expanding ($<100\,R_\odot$) and filling their Roche lobe. Consequently, the strength of the applied winds affects the range of the final black hole masses in non-interacting binaries, making it possible to form systems similar to Gaia BH1 and BH2. Conclusions. We deduce that wide binaries with a black hole and a low mass companion can form at high metallicity without binary interactions. There could be hundreds of such systems in the Milky Way. The mass of the black hole in binaries evolved through the non-interacting channel can potentially provide insights into the wind strength during the progenitors evolution., Comment: 8+4 pages, 6+6 figures, resubmitted to A&A
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- 2024
8. MMAU: A Massive Multi-Task Audio Understanding and Reasoning Benchmark
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Sakshi, S, Tyagi, Utkarsh, Kumar, Sonal, Seth, Ashish, Selvakumar, Ramaneswaran, Nieto, Oriol, Duraiswami, Ramani, Ghosh, Sreyan, and Manocha, Dinesh
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Electrical Engineering and Systems Science - Audio and Speech Processing ,Computer Science - Artificial Intelligence ,Computer Science - Computation and Language ,Computer Science - Sound - Abstract
The ability to comprehend audio--which includes speech, non-speech sounds, and music--is crucial for AI agents to interact effectively with the world. We present MMAU, a novel benchmark designed to evaluate multimodal audio understanding models on tasks requiring expert-level knowledge and complex reasoning. MMAU comprises 10k carefully curated audio clips paired with human-annotated natural language questions and answers spanning speech, environmental sounds, and music. It includes information extraction and reasoning questions, requiring models to demonstrate 27 distinct skills across unique and challenging tasks. Unlike existing benchmarks, MMAU emphasizes advanced perception and reasoning with domain-specific knowledge, challenging models to tackle tasks akin to those faced by experts. We assess 18 open-source and proprietary (Large) Audio-Language Models, demonstrating the significant challenges posed by MMAU. Notably, even the most advanced Gemini Pro v1.5 achieves only 52.97% accuracy, and the state-of-the-art open-source Qwen2-Audio achieves only 52.50%, highlighting considerable room for improvement. We believe MMAU will drive the audio and multimodal research community to develop more advanced audio understanding models capable of solving complex audio tasks., Comment: Project Website: https://sakshi113.github.io/mmau_homepage/
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- 2024
9. Connectivity Labeling Schemes for Edge and Vertex Faults via Expander Hierarchies
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Long, Yaowei, Pettie, Seth, and Saranurak, Thatchaphol
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Computer Science - Data Structures and Algorithms - Abstract
We consider the problem of assigning short labels to the vertices and edges of a graph $G$ so that given any query $\langle s,t,F\rangle$ with $|F|\leq f$, we can determine whether $s$ and $t$ are still connected in $G-F$, given only the labels of $F\cup\{s,t\}$. This problem has been considered when $F\subset E$ (edge faults), where correctness is guaranteed with high probability (w.h.p.) or deterministically, and when $F\subset V$ (vertex faults), both w.h.p.~and deterministically. Our main results are as follows. [Deterministic Edge Faults.] We give a new deterministic labeling scheme for edge faults that uses $\tilde{O}(\sqrt{f})$-bit labels, which can be constructed in polynomial time. This improves on Dory and Parter's [PODC 2021] existential bound of $O(f\log n)$ (requiring exponential time to compute) and the efficient $\tilde{O}(f^2)$-bit scheme of Izumi, Emek, Wadayama, and Masuzawa [PODC 2023]. Our construction uses an improved edge-expander hierarchy and a distributed coding technique based on Reed-Solomon codes. [Deterministic Vertex Faults.] We improve Parter, Petruschka, and Pettie's [STOC 2024] deterministic $O(f^7\log^{13} n)$-bit labeling scheme for vertex faults to $O(f^4\log^{7.5} n)$ bits, using an improved vertex-expander hierarchy and better sparsification of shortcut graphs. [Randomized Edge/Verex Faults.] We improve the size of Dory and Parter's [PODC 2021] randomized edge fault labeling scheme from $O(\min\{f+\log n, \log^3 n\})$ bits to $O(\min\{f+\log n, \log^2 n\log f\})$ bits, shaving a $\log n/\log f$ factor. We also improve the size of Parter, Petruschka, and Pettie's [STOC 2024] randomized vertex fault labeling scheme from $O(f^3\log^5 n)$ bits to $O(f^2\log^6 n)$ bits, which comes closer to their $\Omega(f)$-bit lower bound., Comment: To appear in SODA 2025
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- 2024
10. Generating Infinitely Many Hyperbolic Knots with Plats
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Engelhardt, Carolyn and Hovland, Seth
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Mathematics - Geometric Topology ,57K10, 57K20, 57K30 - Abstract
In this paper we study the relationships between links in plat position, the dynamics of the braid group, and Heegaard splittings of double branched covers of $S^3$ over a link. These relationships offer new ways to view links in plat position and a new tool kit for analyzing links. In particular, we show that the Hempel distance of the Heegaard splitting of the double branched cover obtained from a plat is a lower bound for the Hempel distance of that plat. Using the Hempel distance of a knot in bridge position and pseudo-Anosov braids we obtain our main result: a construction of infinitely many sequences of prime hyperbolic $n$-bridge knots for $n \geq 3$, infinitely many of which are distinct. We consider known results to show that the knot genus and hyperbolic volume of these knots are bounded below by a linear function. As a further result we show that the plat closure of a 6-braid is generically hyperbolic., Comment: 15 pages, 12 figures, Comments Welcome!
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- 2024
11. Sketching, Moment Estimation, and the L\'evy-Khintchine Representation Theorem
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Pettie, Seth and Wang, Dingyu
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Computer Science - Data Structures and Algorithms ,Mathematics - Probability - Abstract
In the $d$-dimensional turnstile streaming model, a frequency vector $\mathbf{x}=(\mathbf{x}(1),\ldots,\mathbf{x}(n))\in (\mathbb{R}^d)^n$ is updated entry-wisely over a stream. We consider the problem of \emph{$f$-moment estimation} for which one wants to estimate $$f(\mathbf{x})=\sum_{v\in[n]}f(\mathbf{x}(v))$$ with a small-space sketch. In this work we present a simple and generic scheme to construct sketches with the novel idea of hashing indices to \emph{L\'evy processes}, from which one can estimate the $f$-moment $f(\mathbf{x})$ where $f$ is the \emph{characteristic exponent} of the L\'evy process. The fundamental \emph{L\'evy-Khintchine{} representation theorem} completely characterizes the space of all possible characteristic exponents, which in turn characterizes the set of $f$-moments that can be estimated by this generic scheme. The new scheme has strong explanatory power. It unifies the construction of many existing sketches ($F_0$, $L_0$, $L_2$, $L_\alpha$, $L_{p,q}$, etc.) and it implies the tractability of many nearly periodic functions that were previously unclassified. Furthermore, the scheme can be conveniently generalized to multidimensional cases ($d\geq 2$) by considering multidimensional L\'evy processes and can be further generalized to estimate \emph{heterogeneous moments} by projecting different indices with different L\'evy processes. We conjecture that the set of tractable functions can be characterized using the L\'evy-Khintchine representation theorem via what we called the \emph{Fourier-Hahn-L\'evy} method.
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- 2024
12. Do Audio-Language Models Understand Linguistic Variations?
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Selvakumar, Ramaneswaran, Kumar, Sonal, Giri, Hemant Kumar, Anand, Nishit, Seth, Ashish, Ghosh, Sreyan, and Manocha, Dinesh
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Computer Science - Sound ,Computer Science - Machine Learning ,Electrical Engineering and Systems Science - Audio and Speech Processing - Abstract
Open-vocabulary audio language models (ALMs), like Contrastive Language Audio Pretraining (CLAP), represent a promising new paradigm for audio-text retrieval using natural language queries. In this paper, for the first time, we perform controlled experiments on various benchmarks to show that existing ALMs struggle to generalize to linguistic variations in textual queries. To address this issue, we propose RobustCLAP, a novel and compute-efficient technique to learn audio-language representations agnostic to linguistic variations. Specifically, we reformulate the contrastive loss used in CLAP architectures by introducing a multi-view contrastive learning objective, where paraphrases are treated as different views of the same audio scene and use this for training. Our proposed approach improves the text-to-audio retrieval performance of CLAP by 0.8%-13% across benchmarks and enhances robustness to linguistic variation., Comment: 15 pages
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- 2024
13. UVCANDELS: Catalogs of photometric redshifts and galaxy physical properties
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Mehta, Vihang, Rafelski, Marc, Sunnquist, Ben, Teplitz, Harry I., Scarlata, Claudia, Wang, Xin, Fontana, Adriano, Hathi, Nimish P., Iyer, Kartheik G., Alavi, Anahita, Colbert, James, Grogin, Norman, Koekemoer, Anton, Nedkova, Kalina V., Hayes, Matthew, Prichard, Laura, Siana, Brian, Smith, Brent M., Windhorst, Rogier, Ashcraft, Teresa, Bagley, Micaela, Baronchelli, Ivano, Barro, Guillermo, Blanche, Alex, Broussard, Adam, Carleton, Timothy, Chartab, Nima, Codoreanu, Alex, Cohen, Seth, Conselice, Christopher, Dai, Y. Sophia, Darvish, Behnam, Dave, Romeel, DeGroot, Laura, De Mello, Duilia, Dickinson, Mark, Emami, Najmeh, Ferguson, Henry, Ferreira, Leonardo, Finkelstein, Keely, Finkelstein, Steven, Gardner, Jonathan P., Gawiser, Eric, Gburek, Timothy, Giavalisco, Mauro, Grazian, Andrea, Gronwall, Caryl, Guo, Yicheng, Haro, Pablo Arrabal, Hemmati, Shoubaneh, Howell, Justin, Jansen, Rolf A., Ji, Zhiyuan, Kaviraj, Sugata, Kim, Keunho J., Kurczynski, Peter, Lazar, Ilin, Lucas, Ray A., MacKenty, John, Mantha, Kameswara Bharadwaj, Martin, Alec, Martin, Garreth, McCabe, Tyler, Mobasher, Bahram, Morales, Alexa M., O'Connell, Robert, Olsen, Charlotte, Otteson, Lillian, Ravindranath, Swara, Redshaw, Caleb, Rutkowski, Michael, Robertson, Brant, Sattari, Zahra, Soto, Emmaris, Sun, Lei, Taamoli, Sina, Vanzella, Eros, Yung, L. Y. Aaron, and Zabelle, Bonnabelle
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Astrophysics - Astrophysics of Galaxies - Abstract
The UltraViolet imaging of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey Fields (UVCANDELS) program provides deep HST F275W and F435W imaging over four CANDELS fields (GOODS-N, GOODS-S, COSMOS, and EGS). We combine this newly acquired UV imaging with existing HST imaging from CANDELS as well as existing ancillary data to obtain robust photometric redshifts and reliable estimates for galaxy physical properties for over 150,000 galaxies in the $\sim$430 arcmin$^2$ UVCANDELS area. Here, we leverage the power of the new UV photometry to not only improve the photometric redshift measurements in these fields, but also constrain the full redshift probability distribution combining multiple redshift fitting tools. Furthermore, using the full UV-to-IR photometric dataset, we measure the galaxy physical properties by fitting templates from population synthesis models with two different parameterizations (flexible and fixed-form) of the star-formation histories (SFHs). Compared to the flexible SFH parametrization, we find that the fixed-form SFHs systematically underestimate the galaxy stellar masses, both at the low- ($\lesssim10^9 M_\odot$) and high- ($\gtrsim10^{10} M_\odot$) mass end, by as much as $\sim0.5$ dex. This underestimation is primarily due the limited ability of fixed-form SFH parameterization to simultaneously capture the chaotic nature of star-formation in these galaxies., Comment: 22 pages, 6 figures; accepted to ApJS; catalogs available via MAST
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- 2024
14. PAT: Parameter-Free Audio-Text Aligner to Boost Zero-Shot Audio Classification
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Seth, Ashish, Selvakumar, Ramaneswaran, Kumar, Sonal, Ghosh, Sreyan, and Manocha, Dinesh
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Computer Science - Sound ,Electrical Engineering and Systems Science - Audio and Speech Processing - Abstract
Audio-Language Models (ALMs) have demonstrated remarkable performance in zero-shot audio classification. In this paper, we introduce PAT (Parameter-free Audio-Text aligner), a simple and training-free method aimed at boosting the zero-shot audio classification performance of CLAP-like ALMs. To achieve this, we propose to improve the cross-modal interaction between audio and language modalities by enhancing the representations for both modalities using mutual feedback. Precisely, to enhance textual representations, we propose a prompt ensemble algorithm that automatically selects and combines the most relevant prompts from a datastore with a large pool of handcrafted prompts and weighs them according to their relevance to the audio. On the other hand, to enhance audio representations, we reweigh the frame-level audio features based on the enhanced textual information. Our proposed method does not require any additional modules or parameters and can be used with any existing CLAP-like ALM to improve zero-shot audio classification performance. We experiment across 18 diverse benchmark datasets and 6 ALMs and show that the PAT outperforms vanilla zero-shot evaluation with significant margins of 0.42%-27.0%. Additionally, we demonstrate that PAT maintains robust performance even when input audio is degraded by varying levels of noise. Our code will be open-sourced upon acceptance., Comment: 18 pages
- Published
- 2024
15. EH-MAM: Easy-to-Hard Masked Acoustic Modeling for Self-Supervised Speech Representation Learning
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Seth, Ashish, Selvakumar, Ramaneswaran, Sakshi, S, Kumar, Sonal, Ghosh, Sreyan, and Manocha, Dinesh
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Computer Science - Sound ,Computer Science - Artificial Intelligence ,Computer Science - Computation and Language ,Computer Science - Machine Learning ,Electrical Engineering and Systems Science - Audio and Speech Processing - Abstract
In this paper, we present EH-MAM (Easy-to-Hard adaptive Masked Acoustic Modeling), a novel self-supervised learning approach for speech representation learning. In contrast to the prior methods that use random masking schemes for Masked Acoustic Modeling (MAM), we introduce a novel selective and adaptive masking strategy. Specifically, during SSL training, we progressively introduce harder regions to the model for reconstruction. Our approach automatically selects hard regions and is built on the observation that the reconstruction loss of individual frames in MAM can provide natural signals to judge the difficulty of solving the MAM pre-text task for that frame. To identify these hard regions, we employ a teacher model that first predicts the frame-wise losses and then decides which frames to mask. By learning to create challenging problems, such as identifying harder frames and solving them simultaneously, the model is able to learn more effective representations and thereby acquire a more comprehensive understanding of the speech. Quantitatively, EH-MAM outperforms several state-of-the-art baselines across various low-resource speech recognition and SUPERB benchmarks by 5%-10%. Additionally, we conduct a thorough analysis to show that the regions masked by EH-MAM effectively capture useful context across speech frames.
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- 2024
16. Mining Hierarchies with Conviction: Constructing the CS1 Skill Hierarchy with Pairwise Comparisons over Skill Distributions
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Newar, Dip Kiran Pradhan, Fowler, Max, Smith IV, David H., and Poulsen, Seth
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Computer Science - Human-Computer Interaction - Abstract
The skills taught in introductory programming courses are categorized into 1) \textit{explaining} the purpose of code, 2) the ability to arrange lines of code in correct \textit{sequence }, and 3) the ability to \textit{trace} through the execution of a program, and 4) the ability to \textit{write} code from scratch. Knowing if a programming skill is a prerequisite to another would benefit students, particularly those new to programming, by allowing them to encounter new topics in the optimal skill sequence. In this study, we used the conviction measure from association rule mining to perform pair-wise comparisons of five skills: Write, Trace, Reverse trace, Sequence, and Explain code. We used the data from four exams with more than 600 participants in each exam from a public university in the United States, where students solved programming assignments of different skills for several programming topics. Our findings matched the previous finding that tracing is a prerequisite for students to learn to write code. But, contradicting the previous claims, our analysis showed that writing code is a prerequisite skill to explaining code and that sequencing code is not a prerequisite to writing code. Our research can help instructors by systematically arranging the skills students exercise when encountering a new topic. The goal is to reduce the difficulties students experience when learning that topic.
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- 2024
17. The Moral Case for Using Language Model Agents for Recommendation
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Lazar, Seth, Thorburn, Luke, Jin, Tian, and Belli, Luca
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Computer Science - Computers and Society ,Computer Science - Information Retrieval ,K.4 - Abstract
Our information and communication environment has fallen short of the ideals that networked global communication might have served. Identifying all the causes of its pathologies is difficult, but existing recommender systems very likely play a contributing role. In this paper, which draws on the normative tools of philosophy of computing, informed by empirical and technical insights from natural language processing and recommender systems, we make the moral case for an alternative approach. We argue that existing recommenders incentivise mass surveillance, concentrate power, fall prey to narrow behaviourism, and compromise user agency. Rather than just trying to avoid algorithms entirely, or to make incremental improvements to the current paradigm, researchers and engineers should explore an alternative paradigm: the use of language model (LM) agents to source and curate content that matches users' preferences and values, expressed in natural language. The use of LM agents for recommendation poses its own challenges, including those related to candidate generation, computational efficiency, preference modelling, and prompt injection. Nonetheless, if implemented successfully LM agents could: guide us through the digital public sphere without relying on mass surveillance; shift power away from platforms towards users; optimise for what matters instead of just for behavioural proxies; and scaffold our agency instead of undermining it.
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- 2024
18. Anomalously Enhanced Diffusivity of Moir\'e Excitons via Manipulating the Interplay with Correlated Electrons
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Yan, Li, Ma, Lei, Meng, Yuze, Xiao, Chengxin, Chen, Bo, Wu, Qiran, Cui, Jingyuan, Cao, Qingrui, Banerjee, Rounak, Taniguchi, Takashi, Watanabe, Kenji, Tongay, Seth Ariel, Hunt, Benjamin, Cui, Yong-Tao, Yao, Wang, and Shi, Su-Fei
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Condensed Matter - Mesoscale and Nanoscale Physics - Abstract
Semiconducting transitional metal dichalcogenides (TMDCs) moir\'e superlattice provides an exciting platform for manipulating excitons. The in-situ control of moir\'e potential confined exciton would usher in unprecedented functions of excitonic devices but remains challenging. Meanwhile, as a dipolar composite boson, interlayer exciton in the type-II aligned TMDC moir\'e superlattice strongly interacts with fermionic charge carriers. Here, we demonstrate active manipulation of the exciton diffusivity by tuning their interplay with correlated carriers in moir\'e potentials. At fractional fillings where carriers are known to form generalized Wigner crystals, we observed suppressed diffusivity of exciton. In contrast, in Fermi liquid states where carriers dynamically populate all moir\'e traps, the repulsive carrier-exciton interaction can effectively reduce the moir\'e potential confinement seen by the exciton, leading to enhanced diffusivity with the increase of the carrier density. Notably, the exciton diffusivity is enhanced by orders of magnitude near the Mott insulator state, and the enhancement is much more pronounced for the 0-degree than the 60-degree aligned WS2/WSe2 heterobilayer due to the more localized nature of interlayer excitons. Our study inspires further engineering and controlling exotic excitonic states in TMDC moir\'e superlattices for fascinating quantum phenomena and novel excitonic devices.
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- 2024
19. Emulators for stellar profiles in binary population modeling
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Teng, Elizabeth, Demir, Ugur, Doctor, Zoheyr, Srivastava, Philipp M., Lalvani, Shamal, Kalogera, Vicky, Katsaggelos, Aggelos, Andrews, Jeff J., Bavera, Simone S., Briel, Max M., Gossage, Seth, Kovlakas, Konstantinos, Kruckow, Matthias U., Rocha, Kyle Akira, Sun, Meng, Xing, Zepei, and Zapartas, Emmanouil
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Astrophysics - Solar and Stellar Astrophysics ,Astrophysics - Astrophysics of Galaxies ,Astrophysics - Instrumentation and Methods for Astrophysics ,Computer Science - Machine Learning - Abstract
Knowledge about the internal physical structure of stars is crucial to understanding their evolution. The novel binary population synthesis code POSYDON includes a module for interpolating the stellar and binary properties of any system at the end of binary MESA evolution based on a pre-computed set of models. In this work, we present a new emulation method for predicting stellar profiles, i.e., the internal stellar structure along the radial axis, using machine learning techniques. We use principal component analysis for dimensionality reduction and fully-connected feed-forward neural networks for making predictions. We find accuracy to be comparable to that of nearest neighbor approximation, with a strong advantage in terms of memory and storage efficiency. By delivering more information about the evolution of stellar internal structure, these emulators will enable faster simulations of higher physical fidelity with large-scale simulations of binary star population synthesis possible with POSYDON and other population synthesis codes., Comment: 11 pages, 10 figures. Submitted to Astronomy and Computing
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- 2024
20. Ultraviolet extinction correlation with 3D dust maps using white dwarfs
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Sahu, Snehalata, Tremblay, Pier-Emmanuel, Lallement, Rosine, Redfield, Seth, and Gaensicke, Boris T.
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Astrophysics - Solar and Stellar Astrophysics ,Astrophysics - Astrophysics of Galaxies - Abstract
Accurate astrometric and photometric measurements from Gaia have led to the construction of 3D dust extinction maps which can now be used for estimating the integrated extinctions of Galactic sources located within 5 kpc. These maps based on optical observations may not be reliable for use in the ultraviolet (UV) which is more sensitive to reddening. Past studies have focused on studying UV extinction using main-sequence stars but lack comparison with 3D dust maps. White dwarfs with well-modeled hydrogen-dominated (DA) atmospheres provide an advantage over main-sequence stars affected by magnetic activity. In this work, we study the variation of UV extinction with 3D dust maps utilising HST and GALEX observations of DA white dwarfs located within 300 pc. We used HST COS spectroscopic data of 76 sight lines to calculate the optical extinction from Si II column densities and validate our results with the kinematic model predictions of the local interstellar medium. Also, we combined GALEX and Gaia photometric observations of 1158 DA white dwarfs to study UV reddening by comparing observed and modeled colour-colour relations. We calculated GALEX non-linearity corrections and derived reddening coefficients (R(NUV-G) = 6.52 +/- 1.53 and R(FUV-G) = 6.04 +/- 2.41) considering their variations with optical extinction (Av < 0.1 mag), and found them to be in good agreement with known extinction laws. HST analysis suggests a positive bias of 0.01-0.02 mag in the optical extinction from 3D maps depending on the Galactic latitude. These results independently confirm the validity of 3D dust maps to deredden the optical and UV observations of white dwarfs., Comment: Accepted for publication in MNRAS, 16 pages, 15 figures
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- 2024
21. Conformalized Reachable Sets for Obstacle Avoidance With Spheres
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Kwon, Yongseok, Michaux, Jonathan, Isaacson, Seth, Zhang, Bohao, Ejakov, Matthew, Skinner, Katherine A., and Vasudevan, Ram
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Computer Science - Robotics - Abstract
Safe motion planning algorithms are necessary for deploying autonomous robots in unstructured environments. Motion plans must be safe to ensure that the robot does not harm humans or damage any nearby objects. Generating these motion plans in real-time is also important to ensure that the robot can adapt to sudden changes in its environment. Many trajectory optimization methods introduce heuristics that balance safety and real-time performance, potentially increasing the risk of the robot colliding with its environment. This paper addresses this challenge by proposing Conformalized Reachable Sets for Obstacle Avoidance With Spheres (CROWS). CROWS is a novel real-time, receding-horizon trajectory planner that generates probalistically-safe motion plans. Offline, CROWS learns a novel neural network-based representation of a spherebased reachable set that overapproximates the swept volume of the robot's motion. CROWS then uses conformal prediction to compute a confidence bound that provides a probabilistic safety guarantee on the learned reachable set. At runtime, CROWS performs trajectory optimization to select a trajectory that is probabilstically-guaranteed to be collision-free. We demonstrate that CROWS outperforms a variety of state-of-the-art methods in solving challenging motion planning tasks in cluttered environments while remaining collision-free. Code, data, and video demonstrations can be found at https://roahmlab.github.io/crows/, Comment: https://roahmlab.github.io/crows/
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- 2024
22. Alberta Wells Dataset: Pinpointing Oil and Gas Wells from Satellite Imagery
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Seth, Pratinav, Lin, Michelle, Yaw, Brefo Dwamena, Boutot, Jade, Kang, Mary, and Rolnick, David
- Subjects
Computer Science - Computer Vision and Pattern Recognition ,Computer Science - Machine Learning - Abstract
Millions of abandoned oil and gas wells are scattered across the world, leaching methane into the atmosphere and toxic compounds into the groundwater. Many of these locations are unknown, preventing the wells from being plugged and their polluting effects averted. Remote sensing is a relatively unexplored tool for pinpointing abandoned wells at scale. We introduce the first large-scale benchmark dataset for this problem, leveraging medium-resolution multi-spectral satellite imagery from Planet Labs. Our curated dataset comprises over 213,000 wells (abandoned, suspended, and active) from Alberta, a region with especially high well density, sourced from the Alberta Energy Regulator and verified by domain experts. We evaluate baseline algorithms for well detection and segmentation, showing the promise of computer vision approaches but also significant room for improvement.
- Published
- 2024
23. Can LLMs advance democratic values?
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Lazar, Seth and Manuali, Lorenzo
- Subjects
Computer Science - Computers and Society - Abstract
LLMs are among the most advanced tools ever devised for analysing and generating linguistic content. Democratic deliberation and decision-making involve, at several distinct stages, the production and analysis of language. So it is natural to ask whether our best tools for manipulating language might prove instrumental to one of our most important linguistic tasks. Researchers and practitioners have recently asked whether LLMs can support democratic deliberation by leveraging abilities to summarise content, as well as to aggregate opinion over summarised content, and indeed to represent voters by predicting their preferences over unseen choices. In this paper, we assess whether using LLMs to perform these and related functions really advances the democratic values that inspire these experiments. We suggest that the record is decidedly mixed. In the presence of background inequality of power and resources, as well as deep moral and political disagreement, we should be careful not to use LLMs in ways that automate non-instrumentally valuable components of the democratic process, or else threaten to supplant fair and transparent decision-making procedures that are necessary to reconcile competing interests and values. However, while we argue that LLMs should be kept well clear of formal democratic decision-making processes, we think that they can be put to good use in strengthening the informal public sphere: the arena that mediates between democratic governments and the polities that they serve, in which political communities seek information, form civic publics, and hold their leaders to account.
- Published
- 2024
24. rECGnition_v1.0: Arrhythmia detection using cardiologist-inspired multi-modal architecture incorporating demographic attributes in ECG
- Author
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Srivastava, Shreya, Kumar, Durgesh, Bedi, Jatin, Seth, Sandeep, and Sharma, Deepak
- Subjects
Electrical Engineering and Systems Science - Signal Processing ,Computer Science - Artificial Intelligence ,Computer Science - Machine Learning - Abstract
A substantial amount of variability in ECG manifested due to patient characteristics hinders the adoption of automated analysis algorithms in clinical practice. None of the ECG annotators developed till date consider the characteristics of the patients in a multi-modal architecture. We employed the XGBoost model to analyze the UCI Arrhythmia dataset, linking patient characteristics to ECG morphological changes. The model accurately classified patient gender using discriminative ECG features with 87.75% confidence. We propose a novel multi-modal methodology for ECG analysis and arrhythmia classification that can help defy the variability in ECG related to patient-specific conditions. This deep learning algorithm, named rECGnition_v1.0 (robust ECG abnormality detection Version 1), fuses Beat Morphology with Patient Characteristics to create a discriminative feature map that understands the internal correlation between both modalities. A Squeeze and Excitation based Patient characteristic Encoding Network (SEPcEnet) has been introduced, considering the patient's demographics. The trained model outperformed the various existing algorithms by achieving the overall F1-score of 0.986 for the ten arrhythmia class classification in the MITDB and achieved near perfect prediction scores of ~0.99 for LBBB, RBBB, Premature ventricular contraction beat, Atrial premature beat and Paced beat. Subsequently, the methodology was validated across INCARTDB, EDB and different class groups of MITDB using transfer learning. The generalizability test provided F1-scores of 0.980, 0.946, 0.977, and 0.980 for INCARTDB, EDB, MITDB AAMI, and MITDB Normal vs. Abnormal Classification, respectively. Therefore, with a more enhanced and comprehensive understanding of the patient being examined and their ECG for diverse CVD manifestations, the proposed rECGnition_v1.0 algorithm paves the way for its deployment in clinics.
- Published
- 2024
25. On the Minimal Theory of Consciousness Implicit in Active Inference
- Author
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Whyte, Christopher J., Corcoran, Andrew W., Robinson, Jonathan, Smith, Ryan, Moran, Rosalyn J., Parr, Thomas, Friston, Karl J., Seth, Anil K., and Hohwy, Jakob
- Subjects
Quantitative Biology - Neurons and Cognition - Abstract
The multifaceted nature of experience poses a challenge to the study of consciousness. Traditional neuroscientific approaches often concentrate on isolated facets, such as perceptual awareness or the global state of consciousness and construct a theory around the relevant empirical paradigms and findings. Theories of consciousness are, therefore, often difficult to compare; indeed, there might be little overlap in the phenomena such theories aim to explain. Here, we take a different approach: starting with active inference, a first principles framework for modelling behaviour as (approximate) Bayesian inference, and building up to a minimal theory of consciousness, which emerges from the shared features of computational models derived under active inference. We review a body of work applying active inference models to the study of consciousness and argue that there is implicit in all these models a small set of theoretical commitments that point to a minimal (and testable) theory of consciousness.
- Published
- 2024
26. Gate-tunable Bose-Fermi mixture in a strongly correlated moir\'e bilayer electron system
- Author
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Mhenni, Amine Ben, Kadow, Wilhelm, Metelski, Mikołaj J., Paulus, Adrian O., Dijkstra, Alain, Watanabe, Kenji, Taniguchi, Takashi, Tongay, Seth Ariel, Barbone, Matteo, Finley, Jonathan J., Knap, Michael, and Wilson, Nathan P.
- Subjects
Condensed Matter - Strongly Correlated Electrons ,Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed Matter - Quantum Gases - Abstract
Quantum gases consisting of species with distinct quantum statistics, such as Bose-Fermi mixtures, can behave in a fundamentally different way than their unmixed constituents. This makes them an essential platform for studying emergent quantum many-body phenomena such as mediated interactions and unconventional pairing. Here, we realize an equilibrium Bose-Fermi mixture in a bilayer electron system implemented in a WS$_{2}$/WSe$_{2}$ moir\'e heterobilayer with strong Coulomb coupling to a nearby moir\'e-free WSe$_{2}$ monolayer. Absent the fermionic component, the underlying bosonic phase manifests as a dipolar excitonic insulator. By injecting excess charges into it, we show that the bosonic phase forms a stable mixture with added electrons but abruptly collapses upon hole doping. We develop a microscopic model to explain the unusual asymmetric stability with respect to electron and hole doping. By studying the Bose-Fermi mixture via monitoring excitonic resonances from both layers, we demonstrate gate-tunability over a wide range in the boson/fermion density phase space, in excellent agreement with theoretical calculations. Our results further the understanding of phases stabilized in moir\'e bilayer electron systems and demonstrate their potential for exploring the exotic properties of equilibrium Bose-Fermi mixtures., Comment: 13 pages, 4 figures. Extended Data: 6 figures. We welcome your feedback!
- Published
- 2024
27. Constraints on Remnant Planetary Systems as a Function of Main-Sequence Mass with HST/COS
- Author
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Rouis, Lou Baya Ould, Hermes, J. J., Gänsicke, Boris T., Sahu, Snehalata, Koester, Detlev, Tremblay, P. -E., Veras, Dimitri, Farihi, Jay, Heintz, Tyler M., Fusillo, Nicola Pietro Gentile, and Redfield, Seth
- Subjects
Astrophysics - Solar and Stellar Astrophysics ,Astrophysics - Earth and Planetary Astrophysics - Abstract
As the descendants of stars with masses less than 8 M$_{\odot}$ on the main sequence, white dwarfs provide a unique way to constrain planetary occurrence around intermediate-mass stars (spectral types BAF) that are otherwise difficult to measure with radial-velocity or transit surveys. We update the analysis of more than 250 ultraviolet spectra of hot ($13{,}000$ K $< T_{\mathrm{eff}} <$ $30{,}000$ K), young (less than $800$ Myr) white dwarfs collected by the Hubble Space Telescope, which reveals that more than 40% of all white dwarfs show photospheric silicon and sometimes carbon, signpost for the presence of remnant planetary systems. However, the fraction of white dwarfs with metals significantly decreases for massive white dwarfs (M$_{\rm WD}~>$ 0.8 M$_{\odot}$), descendants of stars with masses greater than 3.5 M$_{\odot}$ on the main sequence, as just $11^{+6}_{-4}$% exhibit metal pollution. In contrast, $44\pm6$% of a subset of white dwarfs (M$\rm _{WD}~<$ 0.7 M$_{\odot}$) unbiased by the effects of radiative levitation are actively accreting planetary debris. While the population of massive white dwarfs is expected to be influenced by the outcome of binary evolution, we do not find merger remnants to broadly affect our sample. We connect our measured occurrence rates of metal pollution on massive white dwarfs to empirical constraints into planetary formation and survival around stars with masses greater than 3.5 M$_{\odot}$ on the main sequence., Comment: 21 pages, 5 figures, accepted to The Astrophysical Journal (ApJ)
- Published
- 2024
28. Driving with Regulation: Interpretable Decision-Making for Autonomous Vehicles with Retrieval-Augmented Reasoning via LLM
- Author
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Cai, Tianhui, Liu, Yifan, Zhou, Zewei, Ma, Haoxuan, Zhao, Seth Z., Wu, Zhiwen, and Ma, Jiaqi
- Subjects
Computer Science - Artificial Intelligence - Abstract
This work presents an interpretable decision-making framework for autonomous vehicles that integrates traffic regulations, norms, and safety guidelines comprehensively and enables seamless adaptation to different regions. While traditional rule-based methods struggle to incorporate the full scope of traffic rules, we develop a Traffic Regulation Retrieval (TRR) Agent based on Retrieval-Augmented Generation (RAG) to automatically retrieve relevant traffic rules and guidelines from extensive regulation documents and relevant records based on the ego vehicle's situation. Given the semantic complexity of the retrieved rules, we also design a reasoning module powered by a Large Language Model (LLM) to interpret these rules, differentiate between mandatory rules and safety guidelines, and assess actions on legal compliance and safety. Additionally, the reasoning is designed to be interpretable, enhancing both transparency and reliability. The framework demonstrates robust performance on both hypothesized and real-world cases across diverse scenarios, along with the ability to adapt to different regions with ease.
- Published
- 2024
29. Simulation of the high Mach number asymptote for bubble collapse in a compressible Euler fluid
- Author
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Krimans, Daniels, Ruuth, Steven J., and Putterman, Seth
- Subjects
Physics - Fluid Dynamics - Abstract
Cavitation is a process where bubbles form and collapse within a fluid with dynamic, spatially varying pressure. This phenomenon can concentrate energy density by 12 orders of magnitude, creating light-emitting plasma or damaging nearby surfaces. A key question in cavitation theory and experiments is: what are the upper limits of energy density achievable through this spontaneous multiscale process? Among the many physical processes at play, we focus on fluid compressibility, modeled using the Tait-Murnaghan equation of state for a homentropic Euler fluid. We examine spherical cavities corresponding to experimentally realizable sonoluminescing bubbles, whose radius changes by a factor of over 100. These bubbles reach velocities exceeding the speed of sound of the surrounding fluid. However, all-Mach hydrodynamic solvers, such as those implemented using the Basilisk software, can exhibit unphysical behavior even at early times when motion is nearly incompressible. To accurately capture high Mach number motion and resolve dynamics in the sonoluminescence regime, we introduced a uniform bubble approximation for the ideal gas inside the bubble. This leading-order approximation clarifies the significant effects of compressibility. Our results reproduce the equation-of-state-dependent asymptotic power-law region predicted by analytic calculations. This confirms our method's ability to capture high Mach number motion and suggests that the asymptotic regime could be experimentally observed. Convergence of this method is demonstrated for bubbles in both water and liquid lithium, showing that compressibility slows collapse. Additionally, an outgoing shock wave in the compressible fluid is resolved., Comment: 19 pages, 9 figures
- Published
- 2024
30. Accelerating Biological Spatial Cluster Analysis with the Parallel Integral Image Technique
- Author
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Ockerman, Seth, Klamer, Zachary, and Haab, Brian
- Subjects
Computer Science - Computer Vision and Pattern Recognition - Abstract
Spatial cluster analysis (SCA) offers valuable insights into biological images; a common SCA technique is sliding window analysis (SWA). Unfortunately, SWA's computational cost hinders its application to larger images, limiting its use to small-scale images. With advancements in high-resolution microscopy, images now exceed the capabilities of previous SWA approaches, reaching sizes up to 70,000 by 85,000 pixels. To overcome these limitations, this paper introduces the parallel integral image approach to SWA, surpassing previous methods. We achieve a remarkable speedup of 131,806x on small-scale images and consistent speedups of over 10,000x on a variety of large-scale microscopy images. We analyze the computational complexity advantages of the parallel integral image approach and present experimental results that validate the superior performance of integral-image-based methods. Our approach is made available as an open-source Python PIP package available at https://github.com/OckermanSethGVSU/BioPII., Comment: IEEE CIBCB 2023 Short paper available at https://cmte.ieee.org/cis-bbtc/wp-content/uploads/sites/172/IEEE_CIBCB_2023_paper_2015.pdf
- Published
- 2024
31. Simulating Neutron Scattering on an Analog Quantum Processor
- Author
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Bauer, Nora, Ale, Victor, Laurell, Pontus, Huang, Serena, Watabe, Seth, Tennant, David Alan, and Siopsis, George
- Subjects
Quantum Physics - Abstract
Neutron scattering characterization of materials allows for the study of entanglement and microscopic structure, but is inefficient to simulate classically for comparison to theoretical models and predictions. However, quantum processors, notably analog quantum simulators, have the potential to offer an unprecedented, efficient method of Hamiltonian simulation by evolving a state in real time to compute phase transitions, dynamical properties, and entanglement witnesses. Here, we present a method for simulating neutron scattering on QuEra's Aquila processor by measuring the dynamic structure factor (DSF) for the prototypical example of the critical transverse field Ising chain, and propose a method for error mitigation. We provide numerical simulations and experimental results for the performance of the procedure on the hardware, up to a chain of length $L=25$. Additionally, the DSF result is used to compute the quantum Fisher information (QFI) density, where we confirm bipartite entanglement in the system experimentally., Comment: 13 pages, 10 figures
- Published
- 2024
32. The Wallpaper is Ugly: Indoor Localization using Vision and Language
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Pate, Seth and Wong, Lawson L. S.
- Subjects
Computer Science - Computer Vision and Pattern Recognition - Abstract
We study the task of locating a user in a mapped indoor environment using natural language queries and images from the environment. Building on recent pretrained vision-language models, we learn a similarity score between text descriptions and images of locations in the environment. This score allows us to identify locations that best match the language query, estimating the user's location. Our approach is capable of localizing on environments, text, and images that were not seen during training. One model, finetuned CLIP, outperformed humans in our evaluation., Comment: RO-MAN 2023
- Published
- 2024
33. The Tale of Two Telescopes: How Hubble Uniquely Complements the James Webb Space Telescope: Galaxies
- Author
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Windhorst, Rogier A., Summers, Jake, Carleton, Timothy, Cohen, Seth H., Croker, Kevin S., Jansen, Rolf A., O'Brien, Rosalia, Smith, Brent M., Conselice, Christopher J., Diego, Jose M., Driver, Simon P., Frye, Brenda, and Yan, Haojing
- Subjects
Astrophysics - Astrophysics of Galaxies - Abstract
In this paper, we present a simple but compelling argument, focusing on galaxy science, for preserving the main imagers and operational modes of the Hubble Space Telescope (HST) for as long as is technically feasible. While star-formation started at redshifts z$\gtrsim$10$-$13, when the universe was less than 300$-$500 Myr old, the CSFH did not peak until z$\simeq$1.9, and has steadily declined since that time. Hence, at least half of all stars in the universe formed in the era where HST provides its unique rest-frame UV view of unobscured young, massive stars tracing cosmic star-formation. By rendering a subset of the 556.3 hours of available HST images in 12 filters of the Hubble Ultra Deep Field (HUDF) in an appropriate mix of colors, we illustrate the unique capabilities of HST for galaxy science emphasizing that rest-frame UV$-$optical wavelength range. We then contrast this with the 52.7 publicly available hours of JWST/NIRCam images in 8 filters of the same HUDF area from the JADES project, rendering these at the redder near-IR wavelengths to illustrate the unique capabilities of JWST to detect older stellar populations at higher redshifts, as well as very dusty stellar populations and Active Galactic Nuclei (AGN). HST uniquely probes (unobscured) young, hot, massive stars in galaxies, while JWST reveals more advanced stages of older stellar populations, as well as relatively short-lived phases where galaxies produce and shed a lot of dust from intense star-formation, and the very high redshift universe (z$\gtrsim$10$-$11) not accessible by HST. We conclude that HST and JWST are highly complementary facilities that took decades to build to ensure decades of operation. To maximize return on investment on both HST and JWST, ways will need to be found to operate HST imaging instruments in all relevant modes for as long as possible into the JWST mission., Comment: White paper submitted to NASA/STScI for the HST Senior Review of 2024. The HST+JWST PDF images are too big for astro-ph. Please view their full resolution PDF files on: http://www.asu.edu/clas/hst/www/jwst2024/windhorst_HST_SeniorReview2024_v4.pdf
- Published
- 2024
34. A Mathematical Perspective on Neurophenomenology
- Author
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Da Costa, Lancelot, Sandved-Smith, Lars, Friston, Karl, Ramstead, Maxwell J. D., and Seth, Anil K.
- Subjects
Quantitative Biology - Neurons and Cognition - Abstract
In the context of consciousness studies, a key challenge is how to rigorously conceptualise first-person phenomenological descriptions of lived experience and their relation to third-person empirical measurements of the activity or dynamics of the brain and body. Since the 1990s, there has been a coordinated effort to explicitly combine first-person phenomenological methods, generating qualitative data, with neuroscientific techniques used to describe and quantify brain activity under the banner of "neurophenomenology". Here, we take on this challenge and develop an approach to neurophenomenology from a mathematical perspective. We harness recent advances in theoretical neuroscience and the physics of cognitive systems to mathematically conceptualise first-person experience and its correspondence with neural and behavioural dynamics. Throughout, we make the operating assumption that the content of first-person experience can be formalised as (or related to) a belief (i.e. a probability distribution) that encodes an organism's best guesses about the state of its external and internal world (e.g. body or brain) as well as its uncertainty. We mathematically characterise phenomenology, bringing to light a tool-set to quantify individual phenomenological differences and develop several hypotheses including on the metabolic cost of phenomenology and on the subjective experience of time. We conceptualise the form of the generative passages between first- and third-person descriptions, and the mathematical apparatus that mutually constrains them, as well as future research directions. In summary, we formalise and characterise first-person subjective experience and its correspondence with third-person empirical measurements of brain and body, offering hypotheses for quantifying various aspects of phenomenology to be tested in future work., Comment: 15 pages, 4 figures
- Published
- 2024
35. Positive-Sum Fairness: Leveraging Demographic Attributes to Achieve Fair AI Outcomes Without Sacrificing Group Gains
- Author
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Belhadj, Samia, Park, Sanguk, Seth, Ambika, Dar, Hesham, and Kooi, Thijs
- Subjects
Computer Science - Machine Learning ,Computer Science - Artificial Intelligence ,Computer Science - Computer Vision and Pattern Recognition ,Computer Science - Computers and Society - Abstract
Fairness in medical AI is increasingly recognized as a crucial aspect of healthcare delivery. While most of the prior work done on fairness emphasizes the importance of equal performance, we argue that decreases in fairness can be either harmful or non-harmful, depending on the type of change and how sensitive attributes are used. To this end, we introduce the notion of positive-sum fairness, which states that an increase in performance that results in a larger group disparity is acceptable as long as it does not come at the cost of individual subgroup performance. This allows sensitive attributes correlated with the disease to be used to increase performance without compromising on fairness. We illustrate this idea by comparing four CNN models that make different use of the race attribute in the training phase. The results show that removing all demographic encodings from the images helps close the gap in performance between the different subgroups, whereas leveraging the race attribute as a model's input increases the overall performance while widening the disparities between subgroups. These larger gaps are then put in perspective of the collective benefit through our notion of positive-sum fairness to distinguish harmful from non harmful disparities.
- Published
- 2024
36. Can LLMs Really Learn to Translate a Low-Resource Language from One Grammar Book?
- Author
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Aycock, Seth, Stap, David, Wu, Di, Monz, Christof, and Sima'an, Khalil
- Subjects
Computer Science - Computation and Language - Abstract
Extremely low-resource (XLR) languages lack substantial corpora for training NLP models, motivating the use of all available resources such as dictionaries and grammar books. Machine Translation from One Book (Tanzer et al., 2024) suggests prompting long-context LLMs with one grammar book enables English-Kalamang translation, an unseen XLR language - a noteworthy case of linguistic knowledge helping an NLP task. We investigate whether the book's grammatical explanations or its parallel examples are most effective for learning XLR translation, finding almost all improvement stems from the parallel examples. Further, we find similar results for Nepali, a seen low-resource language, and achieve performance comparable to an LLM with a grammar book by simply fine-tuning an encoder-decoder translation model. We then investigate where grammar books help by testing two linguistic tasks, grammaticality judgment and gloss prediction, and we explore what kind of grammatical knowledge helps by introducing a typological feature prompt that achieves leading results on these more relevant tasks. We thus emphasise the importance of task-appropriate data for XLR languages: parallel examples for translation, and grammatical data for linguistic tasks. As we find no evidence that long-context LLMs can make effective use of grammatical explanations for XLR translation, we suggest data collection for multilingual XLR tasks such as translation is best focused on parallel data over linguistic description.
- Published
- 2024
37. Responsible AI in Open Ecosystems: Reconciling Innovation with Risk Assessment and Disclosure
- Author
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Chakraborti, Mahasweta, Prestoza, Bert Joseph, Vincent, Nicholas, and Frey, Seth
- Subjects
Computer Science - Human-Computer Interaction ,Computer Science - Artificial Intelligence ,Computer Science - Computers and Society ,Computer Science - Emerging Technologies ,Computer Science - Software Engineering - Abstract
The rapid scaling of AI has spurred a growing emphasis on ethical considerations in both development and practice. This has led to the formulation of increasingly sophisticated model auditing and reporting requirements, as well as governance frameworks to mitigate potential risks to individuals and society. At this critical juncture, we review the practical challenges of promoting responsible AI and transparency in informal sectors like OSS that support vital infrastructure and see widespread use. We focus on how model performance evaluation may inform or inhibit probing of model limitations, biases, and other risks. Our controlled analysis of 7903 Hugging Face projects found that risk documentation is strongly associated with evaluation practices. Yet, submissions (N=789) from the platform's most popular competitive leaderboard showed less accountability among high performers. Our findings can inform AI providers and legal scholars in designing interventions and policies that preserve open-source innovation while incentivizing ethical uptake., Comment: [Under Review][WIP]
- Published
- 2024
38. TOI-2458 b: A mini-Neptune consistent with in situ hot Jupiter formation
- Author
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Šubjak, Ján, Gandolfi, Davide, Goffo, Elisa, Rapetti, David, Nowak, Grzegorz, Mizuki, Toshiyuki, Dai, Fei, Serrano, Luisa M., Wilson, Thomas G., Jankowski, Dawid, Goździewski, Krzysztof, Jenkins, Jon M., Twicken, Joseph D., Winn, Joshua N., Bieryla, Allyson, Cochran, William D., Collins, Karen A., Deeg, Hans J., García, Rafael A., Guenther, Eike W., Hatzes, Artie P., Kabáth, Petr, Korth, Judith, Latham, David W., Livingston, John H., Mathur, Savita, Narita, Norio, Orell-Miquel, Jaume, Pallé, Enric, Persson, Carina M., Redfield, Seth, Schwarz, Richard P., Watanabe, David, and Ziegler, Carl
- Subjects
Astrophysics - Earth and Planetary Astrophysics - Abstract
We report on the discovery and spectroscopic confirmation of TOI-2458 b, a transiting mini-Neptune around an F-type star leaving the main-sequence with a mass of $M_\star=1.05 \pm 0.03$ M$_{\odot}$, a radius of $R_\star=1.31 \pm 0.03$ R$_{\odot}$, an effective temperature of $T_{\rm eff}=6005\pm50$ K, and a metallicity of $-0.10\pm0.05$ dex. By combining TESS photometry with high-resolution spectra acquired with the HARPS spectrograph, we found that the transiting planet has an orbital period of $\sim$3.74 days, a mass of $M_p=13.31\pm0.99$ M$_{\oplus}$ and a radius of $R_p=2.83\pm0.20$ R$_{\oplus}$. The host star TOI-2458 shows a short activity cycle of $\sim$54 days revealed in the HARPS S-index time series. We took the opportunity to investigate other F stars showing activity cycle periods comparable to that of TOI-2458 and found that they have shorter rotation periods than would be expected based on the gyrochronology predictions. In addition, we determined TOI-2458's stellar inclination angle to be $i_\star\,=\,10.6_{-10.6}^{+13.3}$ degrees. We discuss that both phenomena (fast stellar rotation and planet orbit inclination) could be explained by in situ formation of a hot Jupiter interior to TOI-2458 b. It is plausible that this hot Jupiter was recently engulfed by the star. Analysis of HARPS spectra has identified the presence of another planet with a period of $P\,=\,16.55\pm0.06$ days and a minimum mass of $M_p \sin i=10.22\pm1.90$ M$_{\oplus}$., Comment: 22 pages, 17 figures, submitted to Astronomy & Astrophysics
- Published
- 2024
39. Formulating the Proxy Pattern-Mixture Model as a Selection Model to Assist with Sensitivity Analysis
- Author
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Yiadom, Seth Adarkwah and Andridge, Rebecca
- Subjects
Statistics - Methodology ,Statistics - Applications - Abstract
Proxy pattern-mixture models (PPMM) have previously been proposed as a model-based framework for assessing the potential for nonignorable nonresponse in sample surveys and nonignorable selection in nonprobability samples. One defining feature of the PPMM is the single sensitivity parameter, $\phi$, that ranges from 0 to 1 and governs the degree of departure from ignorability. While this sensitivity parameter is attractive in its simplicity, it may also be of interest to describe departures from ignorability in terms of how the odds of response (or selection) depend on the outcome being measured. In this paper, we re-express the PPMM as a selection model, using the known relationship between pattern-mixture models and selection models, in order to better understand the underlying assumptions of the PPMM and the implied effect of the outcome on nonresponse. The selection model that corresponds to the PPMM is a quadratic function of the survey outcome and proxy variable, and the magnitude of the effect depends on the value of the sensitivity parameter, $\phi$ (missingness/selection mechanism), the differences in the proxy means and standard deviations for the respondent and nonrespondent populations, and the strength of the proxy, $\rho^{(1)}$. Large values of $\phi$ (beyond $0.5$) often result in unrealistic selection mechanisms, and the corresponding selection model can be used to establish more realistic bounds on $\phi$. We illustrate the results using data from the U.S. Census Household Pulse Survey., Comment: 25 pages, 6 figures
- Published
- 2024
40. Linear dichroism of the optical properties of SnS and SnSe van der Waals crystals
- Author
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Tołłoczko, Agata K., Ziembicki, Jakub, Grodzicki, Miłosz, Serafińczuk, Jarosław, Tongay, Seth A., Erdi, Melike, Olszowska, Natalia, Rosmus, Marcin, and Kudrawiec, Robert
- Subjects
Condensed Matter - Materials Science ,Physics - Applied Physics - Abstract
Tin monochalcogendies SnS and SnSe, belonging to a familiy of van der Waals crystals isoelectronic to black phosphorus, are know as enivornmetally-friendly materials promisng for thermoelecric conversion applications. However, they exhibit other desired functionalities, such as intrisic linear dichroism of the optical and electronic properties originating from strongly anisotropic orthorhombic crystal structure. This property makes them perfect candidats for polarization-sensitive photodetectors working in near infrared spectral range. We present a comprehensive study of the SnS and SnSe crystals by means of optical spectroscopy and photoemission spectroscopy, supported by ab initio calcualtions. The studies revealed the high sensitivity of the optical response of both materials to the incident light polarization, which we interpret in terms of the electronic band dispersion and orbital composition of the electronic bands, dictating the selection rules. From the photoemission investigation we determine the ionization potential, electron affinity and work function, which are parameters crucial for the design of devices based on semiconductor heterostructures., Comment: 10 pages of Manuscript and 6 pages of Supporting Information, 7 figures and 4 supplementary figures
- Published
- 2024
41. Let's Make a Splan: Risk-Aware Trajectory Optimization in a Normalized Gaussian Splat
- Author
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Michaux, Jonathan, Isaacson, Seth, Adu, Challen Enninful, Li, Adam, Swayampakula, Rahul Kashyap, Ewen, Parker, Rice, Sean, Skinner, Katherine A., and Vasudevan, Ram
- Subjects
Computer Science - Robotics - Abstract
Neural Radiance Fields and Gaussian Splatting have transformed the field of computer vision by enabling photo-realistic representation of complex scenes. Despite this success, they have seen only limited use in real-world robotics tasks such as trajectory optimization. Two key factors have contributed to this limited success. First, it is challenging to reason about collisions in radiance models. Second, it is difficult to perform inference of radiance models fast enough for real-time trajectory synthesis. This paper addresses these challenges by proposing SPLANNING, a risk-aware trajectory optimizer that operates in a Gaussian Splatting model. This paper first derives a method for rigorously upper-bounding the probability of collision between a robot and a radiance field. Second, this paper introduces a normalized reformulation of Gaussian Splatting that enables the efficient computation of the collision bound in a Gaussian Splat. Third, a method is presented to optimize trajectories while avoiding collisions with a scene represented by a Gaussian Splat. Experiments demonstrate that SPLANNING outperforms state-of-the-art methods in generating collision-free trajectories in highly cluttered environments. The proposed system is also tested on a real-world robot manipulator. A project page is available at https://roahmlab.github.io/splanning., Comment: First two authors contributed equally. Project Page: https://roahmlab.github.io/splanning
- Published
- 2024
42. Simultaneously enhancing brightness and purity of WSe$_2$ single photon emitter using high-aspect-ratio nanopillar array on metal
- Author
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Chhaperwal, Mayank, Tongale, Himanshu Madhukar, Hays, Patrick, Watanabe, Kenji, Taniguchi, Takashi, Tongay, Seth Ariel, and Majumdar, Kausik
- Subjects
Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed Matter - Materials Science ,Physics - Applied Physics ,Physics - Optics ,Quantum Physics - Abstract
Monolayer semiconductor transferred on nanopillar arrays provides site-controlled, on-chip single photon emission, which is a scalable light source platform for quantum technologies. However, the brightness of these emitters reported to date often falls short of the perceived requirement for such applications. Also, the single photon purity usually degrades as the brightness increases. Hence, there is a need for a design methodology to achieve enhanced emission rate while maintaining high single photon purity. Using WSe$_2$ on high-aspect-ratio ($\sim 3$ - at least two-fold higher than previous reports) nanopillar arrays, here we demonstrate $>10$ MHz single photon emission rate in the 770-800 nm band that is compatible with quantum memory and repeater networks (Rb-87-D1/D2 lines), and satellite quantum communication. The emitters exhibit excellent purity (even at high emission rates) and improved out-coupling due to the use of a gold back reflector that quenches the emission away from the nanopillar., Comment: Accepted in Nano Letters
- Published
- 2024
43. oMEGACat IV: Constraining Ages of Omega Centauri sub-giant branch stars with HST and MUSE
- Author
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Clontz, C., Seth, A. C., Dotter, A., Häberle, M., Nitschai, M. S., Neumayer, N., Feldmeier-Krause, A., Latour, M., Wang, Z., Souza, S. O., Kacharov, N., Bellini, A., Libralato, M., Pechetti, R., van de Ven, G., and Alfaro-Cuello, M.
- Subjects
Astrophysics - Astrophysics of Galaxies - Abstract
We present age estimates for over 8100 sub-giant branch (SGB) stars in Omega Centauri ($\omega$ Cen) to study its star formation history. Our large data set, which combines multi-wavelength HST photometry with MUSE metallicities, provides an unprecedented opportunity to measure individual stellar ages. We do this by fitting each star's photometry and metallicity with theoretical isochrones, that are embedded with an empirical [C+N+O]-[Fe/H] relation specifically for $\omega$ Cen. The bulk of the stars have ages between 13 and 10 Gyr, with the mean stellar age being 12.08$\pm$0.01 Gyrs and the median age uncertainty being 0.68 Gyrs. From these ages we construct the most complete age-metallicity relation (AMR) for $\omega$ Cen to date. We find that the mean age of stars decreases with increasing metallicity and find two distinct streams in the age-metallicity plane, hinting at different star formation pathways. We derive an intrinsic spread in the ages of 0.75$\pm$0.01 Gyr for the whole cluster, with the age spread showing a clear increase with metallicity. We verify the robustness of our age estimations by varying isochrone parameters and constraining our systematics. We find the C+N+O relation to be the most critical consideration for constraining the AMR. We also present the SGB chromosome map with age information. In the future, these stellar ages could be combined with chemical abundances to study age differences in subpopulations, and uncover the chemical evolution history of this massive nuclear star cluster., Comment: 23 pages, 11 figures
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- 2024
44. Comparison and calibration of MP2RAGE quantitative T1 values to multi-TI inversion recovery T1 values
- Author
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Saunders, Adam M., Kim, Michael E., Gao, Chenyu, Remedios, Lucas W., Krishnan, Aravind R., Schilling, Kurt G., O'Grady, Kristin P., Smith, Seth A., and Landman, Bennett A.
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Electrical Engineering and Systems Science - Image and Video Processing - Abstract
While typical qualitative T1-weighted magnetic resonance images reflect scanner and protocol differences, quantitative T1 mapping aims to measure T1 independent of these effects. Changes in T1 in the brain reflect chemical and physical changes in brain tissue, such as the demyelination of axons in multiple sclerosis. Magnetization-prepared two rapid acquisition gradient echo (MP2RAGE) is an acquisition protocol that allows for efficient T1 mapping with a much lower scan time per slice compared to multi-TI inversion recovery (IR) protocols. We collect and register B1-corrected MP2RAGE acquisitions with an additional inversion time (MP3RAGE) alongside multi-TI selective inversion recovery acquisitions for four subjects and find a tissue-dependent bias between the derived T1 values. We train a patch-based ResNet-18 to calibrate the MP3RAGE T1 values to the multi-TI IR T1 values, incorporating the standard deviation of T1 calculated from a Monte Carlo simulation as an additional channel. Across four folds, the error between the MP2RAGE and T1 maps varies substantially (RMSE in white matter: 0.30 +/- 0.01 seconds, subcortical gray matter: 0.26 +/- 0.02 seconds, cortical gray matter: 0.36 +/- 0.02 seconds). Our network reduces the RMSE significantly (RMSE in white matter: 0.11 +/- 0.02 seconds, subcortical gray matter: 0.10 +/- 0.02 seconds, cortical gray matter: 0.17 +/- 0.03 seconds). Adding the standard deviation channel does not substantially change the RMSE. Using limited paired training data from both sequences, we can reduce the error between quantitative imaging methods and calibrate to one of the protocols with a neural network., Comment: 20 pages, 10 figures. Submitted to Magnetic Resonance Imaging
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- 2024
45. PoTATO: A Dataset for Analyzing Polarimetric Traces of Afloat Trash Objects
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Batista, Luis Felipe Wolf, Khazem, Salim, Adibi, Mehran, Hutchinson, Seth, and Pradalier, Cedric
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Computer Science - Computer Vision and Pattern Recognition - Abstract
Plastic waste in aquatic environments poses severe risks to marine life and human health. Autonomous robots can be utilized to collect floating waste, but they require accurate object identification capability. While deep learning has been widely used as a powerful tool for this task, its performance is significantly limited by outdoor light conditions and water surface reflection. Light polarization, abundant in such environments yet invisible to the human eye, can be captured by modern sensors to significantly improve litter detection accuracy on water surfaces. With this goal in mind, we introduce PoTATO, a dataset containing 12,380 labeled plastic bottles and rich polarimetric information. We demonstrate under which conditions polarization can enhance object detection and, by providing raw image data, we offer an opportunity for the research community to explore novel approaches and push the boundaries of state-of-the-art object detection algorithms even further. Code and data are publicly available at https://github.com/luisfelipewb/ PoTATO/tree/eccv2024., Comment: ECCV24 TRICKY workshop, Sep 2024, Milano (Italy), Italy
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- 2024
46. DiffESM: Conditional Emulation of Temperature and Precipitation in Earth System Models with 3D Diffusion Models
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Bassetti, Seth, Hutchinson, Brian, Tebaldi, Claudia, and Kravitz, Ben
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Physics - Atmospheric and Oceanic Physics ,Computer Science - Machine Learning ,Computer Science - Neural and Evolutionary Computing ,Physics - Geophysics - Abstract
Earth System Models (ESMs) are essential for understanding the interaction between human activities and the Earth's climate. However, the computational demands of ESMs often limit the number of simulations that can be run, hindering the robust analysis of risks associated with extreme weather events. While low-cost climate emulators have emerged as an alternative to emulate ESMs and enable rapid analysis of future climate, many of these emulators only provide output on at most a monthly frequency. This temporal resolution is insufficient for analyzing events that require daily characterization, such as heat waves or heavy precipitation. We propose using diffusion models, a class of generative deep learning models, to effectively downscale ESM output from a monthly to a daily frequency. Trained on a handful of ESM realizations, reflecting a wide range of radiative forcings, our DiffESM model takes monthly mean precipitation or temperature as input, and is capable of producing daily values with statistical characteristics close to ESM output. Combined with a low-cost emulator providing monthly means, this approach requires only a small fraction of the computational resources needed to run a large ensemble. We evaluate model behavior using a number of extreme metrics, showing that DiffESM closely matches the spatio-temporal behavior of the ESM output it emulates in terms of the frequency and spatial characteristics of phenomena such as heat waves, dry spells, or rainfall intensity., Comment: Accepted for publication in Journal of Advances in Modeling Earth Systems
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- 2024
47. A Luminous X-ray AGN in the Dwarf-Dwarf Galaxy Merger RGG 66
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Kimbrell, Seth and Reines, Amy
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Astrophysics - Astrophysics of Galaxies - Abstract
We present the discovery of a luminous X-ray AGN in the dwarf galaxy merger RGG 66. The black hole is predicted to have a mass of $M_{\rm BH} \sim 10^{5.4} M_\odot$ and to be radiating close to its Eddington limit ($L_{\rm bol}/L_{\rm Edd} \sim 0.75$). The AGN in RGG 66 is notable both for its presence in a late-stage dwarf-dwarf merger and for its luminosity of $L_{\rm 2-10~keV} = 10^{42.2}$ erg s$^{-1}$, which is among the most powerful AGNs known in nearby dwarf galaxies. The X-ray spectrum has a best-fit photon index of $\Gamma = 2.4$ and an intrinsic absorption of $N_H \sim 10^{21}$ cm$^{-2}$. These results come from a follow-up {\it Chandra X-ray Observatory} study of four irregular/disturbed dwarf galaxies with evidence for hosting AGNs based on optical spectroscopy. The remaining three dwarf galaxies do not have detectable X-ray sources with upper limits of $L_{\rm 2-10~ keV} \lesssim 10^{40}$ erg s$^{-1}$. Taken at face value, our results on RGG 66 suggest that mergers may trigger the most luminous of AGNs in the dwarf galaxy regime, just as they are suspected to do in more massive galaxy mergers., Comment: 9 pages, 6 figures, Accepted for publication in ApJ; bold font removed from text
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- 2024
48. Increased Brightness and Reduced Efficiency Droop in Perovskite Quantum Dot Light-Emitting Diodes using Carbazole-Based Phosphonic Acid Interface Modifiers
- Author
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Shen, Gillian, Zhang, Yadong, Juarez, Julisa, Contreras, Hannah, Sindt, Collin, Xu, Yiman, Kline, Jessica, Barlow, Stephen, Reichmanis, Elsa, Marder, Seth R., and Ginger, David S.
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Condensed Matter - Materials Science ,Condensed Matter - Mesoscale and Nanoscale Physics - Abstract
We demonstrate the use of [2-($\textit{9H}$-carbazol-9-yl)ethyl]phosphonic acid (2PACz) and [2-(3,6-di-$\textit{tert}$-butyl-$\textit{9H}$-carbazol-9-yl)ethyl]phosphonic acid (t-Bu-2PACz) as anode modification layers in metal-halide perovskite quantum dot light-emitting diodes (QLEDs). Compared to conventional QLED structures with PEDOT:PSS (poly(3,4-ethylenedioxythiophene) polystyrene sulfonate)/PVK (poly(9-vinylcarbazole)) hole-transport layers, QLEDs made with phosphonic acid (PA)-modified indium tin oxide (ITO) anodes show an over 7-fold increase in brightness, achieving a brightness of 373,000 cd m$^{-2}$, one of the highest brightnesses reported to date for colloidal perovskite QLEDs. Importantly, the onset of efficiency roll-off, or efficiency droop, occurs at ~1000-fold higher current density for QLEDs made with PA-modified anodes compared to control QLEDs made with conventional PEDOT:PSS/PVK hole transport layers, allowing the devices to sustain significantly higher levels of external quantum efficiency at a brightness of >10$^{5}$ cd m$^{-2}$. Steady-state and time-resolved photoluminescence measurements indicate these improvements are due to a combination of multiple factors, including reducing quenching of photoluminescence at the PEDOT:PSS interface and reducing photoluminescence efficiency loss at high levels of current density.
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- 2024
49. Journalists, Emotions, and the Introduction of Generative AI Chatbots: A Large-Scale Analysis of Tweets Before and After the Launch of ChatGPT
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Lewis, Seth C., Markowitz, David M., and Bunquin, Jon Benedik
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Computer Science - Computational Complexity ,Computer Science - Artificial Intelligence ,Computer Science - Computation and Language - Abstract
As part of a broader look at the impact of generative AI, this study investigated the emotional responses of journalists to the release of ChatGPT at the time of its launch. By analyzing nearly 1 million Tweets from journalists at major U.S. news outlets, we tracked changes in emotional tone and sentiment before and after the introduction of ChatGPT in November 2022. Using various computational and natural language processing techniques to measure emotional shifts in response to ChatGPT's release, we found an increase in positive emotion and a more favorable tone post-launch, suggesting initial optimism toward AI's potential. This research underscores the pivotal role of journalists as interpreters of technological innovation and disruption, highlighting how their emotional reactions may shape public narratives around emerging technologies. The study contributes to understanding the intersection of journalism, emotion, and AI, offering insights into the broader societal impact of generative AI tools.
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- 2024
50. Investigating Ionic Diffusivity in Amorphous Solid Electrolytes using Machine Learned Interatomic Potentials
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Seth, Aqshat, Kulkarni, Rutvij Pankaj, and Gautam, Gopalakrishnan Sai
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Condensed Matter - Materials Science - Abstract
Investigating Li$^+$ transport within the amorphous lithium phosphorous oxynitride (LiPON) framework, especially across a Li||LiPON interface, has proven challenging due to its amorphous nature and varying stoichiometry, necessitating large supercells and long timescales for computational models. Notably, machine learned interatomic potentials (MLIPs) can combine the computational speed of classical force fields with the accuracy of density functional theory (DFT), making them the ideal tool for modelling such amorphous materials. Thus, in this work, we train and validate the neural equivariant Interatomic potential (NequIP) framework on a comprehensive DFT-based dataset consisting of 13,454 chemically relevant structures to describe LiPON. With an optimized training (validation) energy and force mean absolute errors of 5.5 (6.1) meV/atom and 13.6 (13.2) meV/{\AA}, respectively, we employ the trained potential in model Li-transport in both bulk LiPON and across a Li||LiPON interface. Amorphous LiPON structures generated by the optimized potential do resemble those generated by ab initio molecular dynamics, with N being incorporated on non-bridging apical and bridging sites. Subsequent analysis of Li$^+$ diffusivity in the bulk LiPON structures indicates broad agreement with computational and experimental literature so far. Further, we investigate the anisotropy in Li$^+$ transport across the Li(110)||LiPON interface, where we observe Li-transport across the interface to be one order-of-magnitude slower than Li-motion within the bulk Li and LiPON phases. Nevertheless, we note that this anisotropy of Li-transport across the interface is minor and do not expect it to cause any significant impedance buildup. Finally, our work highlights the efficiency of MLIPs in enabling high-fidelity modelling of complex non-crystalline systems over large length and time scales.
- Published
- 2024
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