cssi/SciSciGPT-SciSciNet huggingface dataset:
Spatial and temporal trends in social vulnerability and COVID-19 incidence and death rates in the United States.

BACKGROUND: Socially vulnerable communities may be at higher risk for COVID-19 outbreaks in the US. However, no prior studies examined temporal trends and differential effects of social vulnerability on COVID-19 incidence and death rates. Therefore, we examined temporal trends among counties with high and low social vulnerability to quantify disparities in trends over time. METHODS: We conducted a longitudinal analysis examining COVID-19 incidence and death rates from March 15 to December 31, 2020, for each US county using data from USAFacts. We classified counties using the Social Vulnerability Index (SVI), a percentile-based measure from the Centers for Disease Control and Prevention, with higher values indicating more vulnerability. Using a Bayesian hierarchical negative binomial model, we estimated daily risk ratios (RRs) comparing counties in the first (lower) and fourth (upper) SVI quartiles, adjusting for rurality, percentage in poor or fair health, percentage female, percentage of smokers, county average daily fine particulate matter (PM2.5), percentage of primary care physicians per 100,000 residents, daily temperature and precipitation, and proportion tested for COVID-19. RESULTS: At the outset of the pandemic, the most vulnerable counties had, on average, fewer cases per 100,000 than least vulnerable SVI quartile. However, on March 28, we observed a crossover effect in which the most vulnerable counties experienced higher COVID-19 incidence rates compared to the least vulnerable counties (RR = 1.05, 95% PI: 0.98, 1.12). Vulnerable counties had higher death rates starting on May 21 (RR = 1.08, 95% PI: 1.00,1.16). However, by October, this trend reversed and the most vulnerable counties had lower death rates compared to least vulnerable counties. CONCLUSIONS: The impact of COVID-19 is not static but can migrate from less vulnerable counties to more vulnerable counties and back again over time.
Bordifications of hyperplane arrangements and their curve complexes

The complement of an arrangement of hyperplanes in $\mathbb C^n$ has a natural bordification to a manifold with corners formed by removing (or "blowing up") tubular neighborhoods of the hyperplanes and certain of their intersections. When the arrangement is the complexification of a real simplicial arrangement, the bordification closely resembles Harvey's bordification of moduli space. We prove that the faces of the universal cover of the bordification are parameterized by the simplices of a simplicial complex $\mathcal{C}$, the vertices of which are the irreducible "parabolic subgroups" of the fundamental group of the arrangement complement. So, the complex $\mathcal{C}$ plays a similar role for an arrangement complement as the curve complex does for moduli space. Also, in analogy with curve complexes and with spherical buildings, we prove that $\mathcal{C}$ has the homotopy type of a wedge of spheres.
Download Time Analysis for Distributed Storage Codes With Locality and Availability

The paper presents techniques for analyzing the expected download time in distributed storage systems that employ systematic availability codes. These codes provide access to hot data through the systematic server containing the object and multiple recovery groups. When a request for an object is received, it can be replicated (forked) to the systematic server and all recovery groups. We first consider the low-traffic regime and present the close-form expression for the download time. By comparison across systems with availability, maximum distance separable (MDS), and replication codes, we demonstrate that availability codes can reduce download time in some settings but are not always optimal. In the high-traffic regime, the system contains multiple inter-dependent Fork-Join queues, making exact analysis intractable. Accordingly, we present upper and lower bounds on the download time, and an M/G/1 queue approximation for several cases of interest. Via extensive numerical simulations, we evaluate our bounds and demonstrate that the M/G/1 queue approximation has a high degree of accuracy.
Graham's Gatekeeper and Beyond: Juvenile Sentencing and Release Reform in the Wake of Graham and Miller

In Graham v. Florida and Miller v. Alabama, the Supreme Court imposed limits on the use of life sentences for juveniles. The decisions require states and the federal government to craft new procedures when and if courts levy life and lengthy sentences upon juveniles. But the Court’s decisions are not self-actualizing and there is little within them that creates a bright line about the substance or procedures states should follow. This article focuses on three of the questions that states face in the implementation of the Court’s decisions. First, who is the best gatekeeper for the release of these offenders on the back end of sentencing — the judiciary, parole boards, or something new? Second, what procedural and substantive guidance should states provide for these chosen gatekeepers? And, finally, what role will modern risk assessment tools play in this decision making? The answers to these questions must fairly balance public safety with the possibility of redemption the Court recognized is inherent in childhood. They will also affect the public’s perception of legitimacy in the release process. State and the federal government answers to those questions are even more pressing given the applicability of Graham’s rationale to a larger category of offenders — the American Bar Association and American Law Institute both recommend the creation of some form of sentencing review for all juveniles sentenced under an adult regime.Despite the importance of these questions, in the early aftermath of the Court’s opinions, legislative and judicial attention has primarily focused on issues related to the length of sentences that should be alternatives to life terms, the time at which review should occur when life sentences are imposed, and retroactivity. But some pioneering states have passed legislation tinkering with broader reform and legislatures are rapidly taking up the issues presented. Some courts have broadened the reach of Graham and Miller, striking down juvenile life without parole altogether. But many legislatures are embattled over decisions about whether to enact only the perceived minimal requirements of Graham and Miller or whether to extend the Court’s reasoning to broader release policies affording back end sentencing review at reasonable time periods. Choices that provide for expanded but careful opportunities for relief can counterweigh some of the harsh results of juvenile transfer laws that have brought, and continue to bring, increasing numbers of juveniles under the rubric of adult sentencing schemes in ways that were not necessarily intentional or desirable. The Article discusses the implications of the chosen gatekeeper for release and discusses the accompanying procedural and substantive considerations that states and the federal government should consider upon implementation.
Congruences for level 1 cusp forms of half-integral weight

Suppose that $\ell \geq 5$ is prime. For a positive integer $N$ with $4 \mid N$, previous works studied properties of half-integral weight modular forms on $\Gamma_0(N)$ which are supported on finitely many square classes modulo $\ell$, in some cases proving that these forms are congruent to the image of a single variable theta series under some number of iterations of the Ramanujan $\Theta$-operator. Here, we study the analogous problem for modular forms of half-integral weight on $\operatorname{SL}_{2}(\mathbb{Z})$. Let $\eta$ be the Dedekind eta function. For a wide range of weights, we prove that every half-integral weight modular form on $\operatorname{SL}_{2}(\mathbb{Z})$ which is supported on finitely many square classes modulo $\ell$ can be written modulo $\ell$ in terms of $\eta^{\ell}$ and an iterated derivative of $\eta$.
Universality of the least singular value for the sum of random matrices

We consider the least singular value of M=R∗XT+U∗YV, where R, T, U, V are independent Haar-distributed unitary matrices and X, Y are deterministic diagonal matrices. Under weak conditions on X and Y, we show that the limiting distribution of the least singular value of M, suitably rescaled, is the same as the limiting distribution for the least singular value of a matrix of i.i.d. Gaussian random variables. Our proof is based on the dynamical method used by Che and Landon to study the local spectral statistics of sums of Hermitian matrices.
Sequential (Quickest) Change Detection: Classical Results and New Directions

Online detection of changes in stochastic systems, referred to as sequential change detection or quickest change detection, is an important research topic in statistics, signal processing, and information theory, and has a wide range of applications. This survey starts with the basics of sequential change detection, and then moves on to generalizations and extensions of sequential change detection theory and methods. We also discuss some new dimensions that emerge at the intersection of sequential change detection with other areas, along with a selection of modern applications and remarks on open questions.
Transportation inequalities for Markov kernels and their applications

We study the relationship between functional inequalities for a Markov kernel on a metric space X and inequalities of transportation distances on the space of probability measures P(X). Extending results of Luise and Savare on Hellinger–Kantorovich contraction inequalities for the particular case of the heat semigroup on an RCD(K,∞) metric space, we show that more generally, such contraction inequalities are equivalent to reverse Poincare inequalities. We also adapt the “dynamic dual” formulation of the Hellinger–Kantorovich distance to define a new family of divergences on P(X) which generalize the Renyi divergence, and we show that contraction inequalities for these divergences are equivalent to the reverse logarithmic Sobolev and Wang Harnack inequalities. We discuss applications including results on the convergence of Markov processes to equilibrium, and on quasi-invariance of heat kernel measures in finite and infinite-dimensional groups.
A note on calculating the average span of control

This note derives a formula to compute the average span of control of a hierarchical organization, fixing a mistake that had gone undetected in the literature for almost 60 years.
Quantitative uniqueness properties for $L^2$ functions with fast decaying, or sparsely supported, Fourier transform

This paper builds upon two key principles behind the Bourgain-Dyatlov quantitative uniqueness theorem for functions with Fourier transform supported in an Ahlfors regular set. We first provide a characterization of when a quantitative uniqueness theorem holds for functions with very quickly decaying Fourier transform, thereby providing an extension of the classical Paneah-Logvinenko-Sereda theorem. Secondly, we derive a transference result which converts a quantitative uniqueness theorem for functions with fast decaying Fourier transform to one for functions with Fourier transform supported on a fractal set. As well as recovering the result of Bourgain-Dyatlov, we obtain analogous uniqueness results for denser fractals.
Word Alignment by Fine-tuning Embeddings on Parallel Corpora.

Word alignment over parallel corpora has a wide variety of applications, including learning translation lexicons, cross-lingual transfer of language processing tools, and automatic evaluation or analysis of translation outputs. The great majority of past work on word alignment has worked by performing unsupervised learning on parallel text. Recently, however, other work has demonstrated that pre-trained contextualized word embeddings derived from multilingually trained language models (LMs) prove an attractive alternative, achieving competitive results on the word alignment task even in the absence of explicit training on parallel data. In this paper, we examine methods to marry the two approaches: leveraging pre-trained LMs but fine-tuning them on parallel text with objectives designed to improve alignment quality, and proposing methods to effectively extract alignments from these fine-tuned models. We perform experiments on five language pairs and demonstrate that our model can consistently outperform previous state-of-the-art models of all varieties. In addition, we demonstrate that we are able to train multilingual word aligners that can obtain robust performance on different language pairs.
LOME: Large Ontology Multilingual Extraction

We present LOME, a system for performing multilingual information extraction. Given a text document as input, our core system identifies spans of textual entity and event mentions with a FrameNet (Baker et al., 1998) parser. It subsequently performs coreference resolution, fine-grained entity typing, and temporal relation prediction between events. By doing so, the system constructs an event and entity focused knowledge graph. We can further apply third-party modules for other types of annotation, like relation extraction. Our (multilingual) first-party modules either outperform or are competitive with the (monolingual) state-of-the-art. We achieve this through the use of multilingual encoders like XLM-R (Conneau et al., 2020) and leveraging multilingual training data. LOME is available as a Docker container on Docker Hub. In addition, a lightweight version of the system is accessible as a web demo.
Role of water model on ion dissociation at ambient conditions.

We study ion pair dissociation in water at ambient conditions using a combination of classical and ab initio approaches. The goal of this study is to disentangle the sources of discrepancy observed in computed potentials of mean force. In particular, we aim to understand why some models favor the stability of solvent-separated ion pairs vs contact ion pairs. We found that some observed differences can be explained by non-converged simulation parameters. However, we also unveil that for some models, small changes in the solution density can have significant effects on modifying the equilibrium balance between the two configurations. We conclude that the thermodynamic stability of contact and solvent-separated ion pairs is very sensitive to the dielectric properties of the underlying simulation model. In general, classical models are very robust in providing a similar estimation of the contact ion pair stability, while this is much more variable in density functional theory-based models. The barrier to transition from the solvent-separated to contact ion pair is fundamentally dependent on the balance between electrostatic potential energy and entropy. This reflects the importance of water intra- and inter-molecular polarizability in obtaining an accurate description of the screened ion–ion interactions.
Measurement of patient confidence in self-management of atrial fibrillation: Initial validation of the Confidence in Atrial fibriLlation Management (CALM) Scale.

Background The patient experience of atrial fibrillation (AF) involves several daily self-care behaviors and ongoing confidence to manage their condition. Currently, no standardized self-report measure of AF patient confidence exists. The purpose of this study is to provide preliminary support for the reliability and validity of a newly developed confidence in AF management measure. Methods This study provides preliminary analysis of the Confidence in Atrial FibriLlation Management (CALM) scale, which was rationally developed to measure patient confidence related to self-management of AF. The scale was provided to a sample of AF patients N = 120, (59% male) electronically through a patient education platform. Principal component analysis (PCA) and Cronbach's α were employed to provide preliminary assessment of the validity and reliability of the measure. Results PCA identified a four-factor solution. Internal consistency of the CALM was considered excellent with Cronbach's α = .910. Additional PCA confirmed the value of a single factor solution to produce a total confidence score for improved utility and ease of clinical interpretation. Conclusions Initial assessment of a novel scale measuring patient confidence in managing AF provided promising reliability and validity. Patient confidence in self-management of AF may prove useful as a key marker and endpoint of the patient experience beyond QOL.
Fourier restriction above rectangles

In this article, we study the problem of obtaining Lebesgue space inequalities for the Fourier restriction operator associated to rectangular pieces of the paraboloid and perturbations thereof. We state a conjecture for the dependence of the operator norms in these inequalities on the sidelengths of the rectangles, prove that this conjecture follows from (a slight reformulation of the) restriction conjecture for elliptic hypersurfaces, and prove that, if valid, the conjecture is essentially sharp. Such questions arise naturally in the study of restriction inequalities for degenerate hypersurfaces; we demonstrate this connection by using our positive results to prove new restriction inequalities for a class of hypersurfaces having some additive structure.
People’s attitudes toward automated vehicle and transit integration: case study of small urban areas

Previous surveys of people’s attitudes toward automated vehicles (AVs) and transit integration have primarily taken place in large urban areas. AV-transit integration also has a great potential in ...
Projection-Based Implicit Modeling Method (PIMM) for Functionally Graded Lattice Optimization

We propose a projection-based implicit modeling method (PIMM) for functionally graded lattice optimization, which does not require any homogenization techniques. In this method, a parametric projection function is proposed to link the implicit function of functionally graded lattice with the finite element background mesh. To reduce the number of design variables, the radial basis function is utilized to interpolate the implicit design field. The triply periodic minimal surface lattice is employed to demonstrate the proposed method. Several two- and three-dimensional lattice design examples are presented to solve the compliance problems. The proposed PIMM method is flexible and can potentially be extended to design graded irregular porous scaffold and non-periodic lattice infill designs.
Development of an antiepileptogenesis drug screening platform: Effects of everolimus and phenobarbital.

Objective The kainic acid (KA)-induced status epilepticus (SE) model in rats is a well-defined model of epileptogenesis. This model closely recapitulates many of the clinical and pathological characteristics of human temporal lobe epilepsy (TLE) that arise following SE or another neurological insult. Spontaneous recurrent seizures (SRS) in TLE can present after a latent period following a neurological insult (traumatic brain injury, SE event, viral infection, etc.). Moreover, this model is suitable for preclinical studies to evaluate the long-term process of epileptogenesis and screen putative disease-modifying/antiepileptogenic agents. The burden of human TLE is highly variable, similar to the post-KA SE rat model. In this regard, this model may have broad translational relevance. This report thus details the pharmacological characterization and methodological refinement of a moderate-throughput drug screening program using the post-KA-induced SE model of epileptogenesis in male Sprague Dawley rats to identify potential agents that may prevent or modify the burden of SRS. Specifically, we sought to demonstrate whether our protocol could prevent the development of SRS or lead to a reduced frequency/severity of SRS. Methods Rats were administered either everolimus (2-3 mg/kg po) beginning 1, 2, or 24 h after SE onset, or phenobarbital (60 mg/kg ip) beginning 1 h after SE onset. All treatments were administered once/day for 5-7 days. Rats in all studies (n = 12/treatment dose/study) were then monitored intermittently by video-electroencephalography (2 weeks on, 2 weeks off, 2 weeks on epochs) to determine latency to onset of SRS and disease burden. Results Although no adverse side effects were observed in our studies, no treatment significantly modified disease or prevented the presentation of SRS by 6 weeks after SE onset. Significance Neither phenobarbital nor everolimus administered at several time points after SE onset prevented the development of SRS. Nonetheless, we demonstrate a practical and moderate-throughput screen for potential antiepileptogenic agents in a rat model of TLE.
Stress fiber strain recognition by the LIM protein testin is cryptic and mediated by RhoA

The actin cytoskeleton is a key regulator of mechanical processes in cells. The family of LIM domain proteins have recently emerged as important mechanoresponsive cytoskeletal elements capable of s...
Designing Online Platforms for Customized Goods and Services: A Market-Frictions Based Perspective

Through digitalization, online platforms facilitate suppliers to meet market demand with customized offerings, but this business model’s value-creation potential is often hampered by market frictio...
The dynamics of concealment

Abstract Firm managers likely have more information than outsiders. If managers strategically conceal information, market uncertainty will increase. We develop a dynamic corporate disclosure model, estimating the model using the management earnings forecasts of US public companies. The model, based on the buildup of reputations by managers over time, matches key facts about forecast dynamics. We find that 80% of firms strategically manage information, that managers have superior information around half of the time, and that firms conceal information about 40% of the time. Concealment increases market uncertainty by just under 8%, a sizable information loss.
A reciprocal-space formulation of mixed quantum-classical dynamics.

We derive a formulation of mixed quantum–classical dynamics for modeling electronic carriers interacting with phonons in reciprocal space. For dispersionless phonons, we start by expressing the real-space classical coordinates in terms of complex variables. Taking these variables as a Fourier series then yields the reciprocal-space coordinates. Evaluating the electron–phonon interaction term through Ehrenfest’s theorem, we arrive at a reciprocal-space formalism that is equivalent to mean-field mixed quantum–classical dynamics in real space. This equivalence is numerically verified for the Holstein and Peierls models, for which we find the reciprocal-space Hellmann–Feynman forces to involve momentum-derivative contributions in addition to the position-derivative terms commonly seen in real space. To illustrate the advantage of the reciprocal-space formulation, we present a proof of concept for the inexpensive modeling of low-momentum carriers interacting with phonons using a truncated reciprocal-space basis, which is not possible within a real-space formulation.
Synthesis of perfluoroalkylether oxadiazole elastomers

A method for the simultaneous chain extension and crosslinking of perfluoroalkylethers which yields a thermally stable perfluoroalkylether oxadiazole elastomer crosslinked by trifunctional perfluoroalkylether-1,3,5-triazine is reported. In the preparation, hydroxylamine crystals prepared from hydroxylamine hydrochloride to which sodium butoxide had been added is mixed with perfluoroalkylether dinitrile to obtain the monomer, as the nitrile is converted to amidoxime. Monomers are heated at 140 to 200 C to form poly(perfluoroalkylether oxadiazole) with a 1,2,4-oxadiazole structure by a step-growth polymerization reaction. Simultaneous chain extension and crosslinking are observed to occur when the purified monomer is heated directly and when the remaining nitrile in the monomer is allowed to react with excess ammonia to form the corresponding amidine, which is then heated. Weight loss studies show the thermal stability of the perfluoroalkylether elastomer to be generally better than fluorosilicone or polyester elastomers, especially in air, indicating its potential usefulness for high-performance elastomeric applications.
Variational Analysis of Composite Models with Applications to Continuous Optimization

The paper is devoted to a comprehensive study of composite models in variational analysis and optimization the importance of which for numerous theoretical, algorithmic, and applied issues of opera...
Broadening perceptions of economics in a new introductory economics sequence

The article’s authors report on a comprehensive curricular reform aimed at communicating the broad range of social issues that economists study while engaging students in active learning strategies...
Inflation of Poorly Conditioned Zeros of Systems of Analytic Functions

Given a system of analytic functions and an approximate zero, we introduce inflation to transform this system into one with a regular quadratic zero. This leads to a method for isolating a cluster of zeros of the given system.
On‐Line Determination of Optimal Flight Paths for Helicopters

A procedure for computing fuel optimal fixed range trajectories is developed for helicopters. The algorithm uses a simplified dynamic model and a climb-cruise-descent assumption which simplifies the variational problem to an algebraic minimization. Development of the performance model is discussed extensively and representative results for the S-61 and S-76 helicopters are presented. The results show that the model and optimization algorithm are small enough and simple enough to be incorporated into an on-line optimization algorithm.
Fusing Context Into Knowledge Graph for Commonsense Reasoning

Commonsense reasoning requires a model to make presumptions about world events via language understanding. Many methods couple pre-trained language models with knowledge graphs in order to combine the merits in language modeling and entity-based relational learning. However, although a knowledge graph contains rich structural information, it lacks the context to provide a more precise understanding of the concepts and relations. This creates a gap when fusing knowledge graphs into language modeling, especially in the scenario of insufficient paired text-knowledge data. In this paper, we propose to utilize external entity description to provide contextual information for graph entities. For the CommonsenseQA task, our model first extracts concepts from the question and choice, and then finds a related triple between these concepts. Next, it retrieves the descriptions of these concepts from Wiktionary and feed them as additional input to a pre-trained language model, together with the triple. The resulting model can attain much more effective commonsense reasoning capability, achieving state-of-the-art results in the CommonsenseQA dataset with an accuracy of 80.7% (single model) and 83.3% (ensemble model) on the official leaderboard.
Mass Ejections from the Solar Corona into Interplanetary Space

Data are presented that show that during the Skylab era, mass ejections from the solar corona probably contributed at least 3% of the mass flux from the sun. The frequency of the transients is expected to increase with overall activity in the solar cycle, so more than 10% of the sun's mass efflux will be in the form of ejections at solar cycle maximum.
An Affine Approach to Peterson Comparison

The Peterson comparison formula proved by Woodward relates the three-pointed Gromov-Witten invariants for the quantum cohomology of partial flag varieties to those for the complete flag. Another such comparison can be obtained by composing a combinatorial version of the Peterson isomorphism with a result of Lapointe and Morse relating quantum Littlewood-Richardson coefficients for the Grassmannian to k-Schur analogs in the homology of the affine Grassmannian obtained by adding rim hooks. We show that these comparisons on quantum cohomology are equivalent, up to Postnikov’s strange duality isomorphism.
Co-design of Control and Planning for Multi-rotor UAVs with Signal Temporal Logic Specifications

Urban Air Mobility (UAM), or the scenario where multiple manned and Unmanned Aerial Vehicles (UAVs) carry out various tasks over urban airspaces, is a transportation concept of the future that is gaining prominence. UAM missions with complex spatial, temporal and reactive requirements can be succinctly represented using Signal Temporal Logic (STL), a behavioral specification language. However, planning and control of systems with STL specifications is computationally intensive, usually resulting in planning approaches that do not guarantee dynamical feasibility, or control approaches that cannot handle complex STL specifications. Here, we present an approach to co-design the planner and control such that a given STL specification (possibly over multiple UAV s) is satisfied with trajectories that are dynamically feasible and our controller can track them with a bounded tracking-error that the planner accounts for. The tracking controller is formulated for the non-linear dynamics of the individual UAVs, and the tracking error bound is computed for this controller when the trajectories satisfy some kinematic constraints. We also augment an existing multi-UAV STL-based trajectory generator in order to generate trajectories that satisfy such constraints. We show that this co-design allows for trajectories that satisfy a given STL specification, and are also dynamically feasible in the sense that they can be tracked with bounded error. The applicability of this approach is demonstrated through simulations of multi- UAV missions.
Exact, parallelizable dynamic time warping alignment with linear memory

Audio alignment is a fundamental preprocessing step in many MIR pipelines. For two audio clips with M and N frames, respectively, the most popular approach, dynamic time warping (DTW), has O(MN) requirements in both memory and computation, which is prohibitive for frame-level alignments at reasonable rates. To address this, a variety of memory efficient algorithms exist to approximate the optimal alignment under the DTW cost. To our knowledge, however, no exact algorithms exist that are guaranteed to break the quadratic memory barrier. In this work, we present a divide and conquer algorithm that computes the exact globally optimal DTW alignment using O(M+N) memory. Its runtime is still O(MN), trading off memory for a 2x increase in computation. However, the algorithm can be parallelized up to a factor of min(M, N) with the same memory constraints, so it can still run more efficiently than the textbook version with an adequate GPU. We use our algorithm to compute exact alignments on a collection of orchestral music, which we use as ground truth to benchmark the alignment accuracy of several popular approximate alignment schemes at scales that were not previously possible.
Diversity in olfactory receptor repertoires is associated with dietary specialization in a genus of frugivorous bat

Abstract Mammalian olfactory receptor genes (ORs) are a diverse family of genes encoding proteins that directly interact with environmental chemical cues. ORs evolve via gene duplication in a birth-death fashion, neofunctionalizing and pseudogenizing over time. Olfaction is a primary sense used for food detection in plant-visiting bats, but the relationship between dietary specialization and OR repertoire diversity is unclear. Within neotropical Leaf-nosed bats (Phyllostomidae), many lineages are plant specialists, and some have a distinct OR repertoire compared to insectivorous species. Yet, whether specialization on particular plant genera is associated with the evolution of specialized, less diverse OR repertoires has never been tested. Using targeted sequence capture, we sequenced the OR repertoires of three sympatric species of short-tailed fruit bats (Carollia), which vary in their degree of specialization on the fruits of Piper plants. We characterized orthologous vs duplicated receptors among Carollia species, and explored the diversity and redundancy of the receptor gene repertoire. At the species level, the most dedicated Piper specialist, Carollia castanea, had lower OR diversity compared to the two generalists (C. sowelli and C. perspicillata), but we discovered a few unique sets of ORs within C. castanea with high redundancy of similar gene duplicates. These unique receptors potentially enable C. castanea to detect Piper fruit odorants better than its two congeners. Carollia perspicillata, the species with the most generalist diet, had a higher diversity of intact receptors, suggesting the ability to detect a wider range of odorant molecules. Variation among ORs may be a factor in the coexistence of these sympatric species, facilitating the exploitation of different plant resources. Our study sheds light on how gene duplication and changes in OR diversity may play a role in dietary adaptations and underlie ecological interactions between bats and plants.
Einstein–Rosen waves and the Geroch group

Under the action of the Geroch group, the Minkowski metric can be transformed into any vacuum metric with two commuting Killing vectors. In principle, this reduces the problem of deriving vacuum metrics with two commuting Killing vectors to pure algebra. In this article, we use these facts to give a purely algebraic derivation of the Einstein–Rosen metric, which describes a cylindrical gravitational wave. Our derivation has a straightforward extension to gravitational pulse waves.
Mid-infrared nonlinear optics in thin-film lithium niobate on sapphire

Periodically poled thin-film lithium niobate (TFLN) waveguides have emerged as a leading platform for highly efficient frequency conversion in the near-infrared. However, the commonly used silica bottom-cladding results in high absorption loss at wavelengths beyond 2.5 µm. In this work, we demonstrate efficient frequency conversion in a TFLN-on-sapphire platform, which features high transparency up to 4.5 µm. In particular, we report generating mid-infrared light up to 3.66 µm via difference-frequency generation of a fixed 1 µm source and a tunable telecom source, with normalized efficiencies up to 200%/Wcm2. These results show TFLN-on-sapphire to be a promising platform for integrated nonlinear nanophotonics in the mid-infrared.
Optimizing revenue while showing relevant assortments at scale

Abstract Scalable real-time assortment optimization has become essential in e-commerce operations due to the need for personalization and the availability of a large variety of items. While this can be done when there are simplistic assortment choices to be made, the optimization process becomes difficult when imposing constraints on the collection of relevant assortments based on insights by store-managers and historically well-performing assortments. We design fast and flexible algorithms based on variations of binary search that find the (approximately) optimal assortment in this difficult regime. In particular, we revisit the problem of large-scale assortment optimization under the multinomial logit choice model without any assumptions on the structure of the feasible assortments. We speed up the comparison steps using advances in similarity search in the field of information retrieval/machine learning. For an arbitrary collection of assortments, our algorithms can find a solution in time that is sub-linear in the number of assortments, and for the simpler case of cardinality constraints - linear in the number of items (existing methods are quadratic or worse). Empirical validations using a real world dataset (in addition to experiments using semi-synthetic data based on the Billion Prices dataset and several retail transaction datasets) show that our algorithms are competitive ( 3 × − 100 × faster) even when the number of items is ∼ 10 5 ( 10 × larger instances than previously studied).
Transient Hydrodynamic Lattice Cooling by Picosecond Laser Irradiation of Graphite

Recent theories and experiments have suggested hydrodynamic phonon transport features in graphite at unusually high temperatures. Here, we report a picosecond pump-probe thermal reflectance measurement of heat-pulse propagation in graphite. The measurement results reveal transient lattice cooling near the adiabatic center of a $15\text{\ensuremath{-}}\ensuremath{\mu}\mathrm{m}$-diameter ring-shape pump beam at temperatures between 80 and 120 K. While such lattice cooling has not been reported in recent diffraction measurements of second sound in graphite, the observation here is consistent with both hydrodynamic phonon transport theory and prior heat-pulse measurements of second sound in bulk sodium fluoride.
Is Recycling Effective? Evidence from California between 2004 and 2017

Using county data from California between 2004 and 2017, this article exploits changes in households’ exposure to hazardous waste recycling to identify the effects on potential environmental and economic outcomes. While a 10% rise in recycling per household is associated with a 0.28% and 0.94% improvement in air quality and a decline in the number of unhealthy days in a year, recycling is associated with a rise in net energy generation and fuel consumption and not associated with economic activity. There is some evidence that households in zip codes with higher housing values and population density value reductions in hazardous waste.
Coloring invariants of knots and links are often intractable

Let G be a nonabelian, simple group with a nontrivial conjugacy class C⊆G. Let K be a diagram of an oriented knot in S3, thought of as computational input. We show that for each such G and C, the problem of counting homomorphisms π1(S3∖K)→G that send meridians of K to C is almost parsimoniously #P–complete. This work is a sequel to a previous result by the authors that counting homomorphisms from fundamental groups of integer homology 3–spheres to G is almost parsimoniously #P–complete. Where we previously used mapping class groups actions on closed, unmarked surfaces, we now use braid group actions.
Quantum impurity models using superpositions of fermionic Gaussian states: Practical methods and applications

The coherent superposition of nonorthogonal fermionic Gaussian states has been shown to be an efficient approximation to the ground states of quantum impurity problems [Bravyi and Gosset, Commun. Math. Phys. 356, 451 (2017)]. We propose a practical approach for performing a variational calculation based on such states. Our method is based on approximate imaginary-time equations of motion that decouple the dynamics of each Gaussian state forming the ansatz. It is independent of the lattice connectivity of the model and the implementation is highly parallelizable. To benchmark our variational method, we calculate the spin-spin correlation function and R\'enyi entanglement entropy of an Anderson impurity, allowing us to identify the screening cloud and compare to density matrix renormalization group calculations. Secondly, we study the screening cloud of the two-channel Kondo model, a problem difficult to tackle using existing numerical tools.
Reflection length in the general linear and affine groups

We give an intrinsic criterion to tell whether a reflection factorization in the general linear group is reduced, and give a formula for computing reflection length in the general affine group.
Abstraction, Validation, and Generalization for Explainable Artificial Intelligence

Neural network architectures are achieving superhuman performance on an expanding range of tasks. To effectively and safely deploy these systems, their decision-making must be understandable to a wide range of stakeholders. Methods to explain AI have been proposed to answer this challenge, but a lack of theory impedes the development of systematic abstractions which are necessary for cumulative knowledge gains. We propose Bayesian Teaching as a framework for unifying explainable AI (XAI) by integrating machine learning and human learning. Bayesian Teaching formalizes explanation as a communication act of an explainer to shift the beliefs of an explainee. This formalization decomposes any XAI method into four components: (1) the inference to be explained, (2) the explanatory medium, (3) the explainee model, and (4) the explainer model. The abstraction afforded by Bayesian Teaching to decompose any XAI method elucidates the invariances among them. The decomposition of XAI systems enables modular validation, as each of the first three components listed can be tested semi-independently. This decomposition also promotes generalization through recombination of components from different XAI systems, which facilitates the generation of novel variants. These new variants need not be evaluated one by one provided that each component has been validated, leading to an exponential decrease in development time. Finally, by making the goal of explanation explicit, Bayesian Teaching helps developers to assess how suitable an XAI system is for its intended real-world use case. Thus, Bayesian Teaching provides a theoretical framework that encourages systematic, scientific investigation of XAI.
Biking where Black: Connecting transportation planning and infrastructure to disproportionate policing

Author(s): Barajas, JM | Abstract: This study asks whether deficiencies in transportation are associated with disproportionate policing in Chicago using the case of cycling. I examine how the number of bicycle citations issued per street segment are influenced by the availability of bicycle facilities and street characteristics, controlling for crash incidence, police presence, and neighborhood characteristics. Tickets were issued 8 times more often per capita in majority Black tracts and 3 times more often in majority Latino tracts compared to majority white tracts. More tickets were issued on major streets, but up to 85% fewer were issued when those streets had bike facilities, which were less prevalent in Black and Latino neighborhoods. Tickets were not associated with bicycle injury-crashes and inversely associated with vehicle injury-crashes. Infrastructure inequities compound the effects of racially-biased policing in the context of transportation safety strategies. Remedies include the removal of traffic enforcement from safe systems strategies and equitable investment in cycling.
Retreating from Redistribution? Trends in Democratic Party Fidelity to Economic Equality, 1984–2020

During his presidency, Barack Obama described rising economic inequality as “the defining challenge of our time.” But a growing number of scholars and journalists argue that rising inequality is in part a result of the Democratic Party’s diminishing fidelity to an egalitarian economic agenda and its embrace of neoliberalism. In this article, we assess the veracity of this claim through content analysis of all national Democratic Party platforms issued since 1984. We find that assertions of Democratic retreat from economic equality are for the most part exaggerated. Broadly, we argue that Democrats’ support for egalitarian policies has been complex and varied over time, showing a marked decline under the influence of the New Democrats in the 1990s, followed by a significant resurgence thereafter. However, while party support for equalizing policies has rebounded, justification for these policies has varied according to the purported deservingness of beneficiaries. Our findings have important implications for debates concerning Democratic Party change, the politics of inequality, and the policy agenda of the incoming Biden administration.
Switched Systems as Hybrid Programs

Abstract Real world systems of interest often feature interactions between discrete and continuous dynamics. Various hybrid system formalisms have been used to model and analyze this combination of dynamics, ranging from mathematical descriptions, e.g., using impulsive differential equations and switching, to automata-theoretic and language-based approaches. This paper bridges two such formalisms by showing how various classes of switched systems can be modeled using the language of hybrid programs from differential dynamic logic (dL). The resulting models enable the formal specification and verification of switched systems using dL and its existing deductive verification tools such as KeYmaera X. Switched systems also provide a natural avenue for the generalization of dL’s deductive proof theory for differential equations. The completeness results for switched system invariants proved in this paper enable effective safety verification of those systems in dL.
Pimples reduce and dimples enhance flat dielectric surface image repulsion.

In solid–liquid, or liquid–liquid, interfaces with dielectric contrast, charged particles interact with the induced polarization charge of the interface. These interactions contribute to an effective self-energy of the bulk ions and mediate ion–ion interactions. For flat interfaces, the self-energy and the mediated interactions are neatly constructed by the image charge method. For other geometries, explicit results are scarce and the problem must be treated via approximations or direct computation. The case of interfaces with roughness is of great practical importance. This article provides analytical results, valid to first-order in perturbation theory, for the self-energy of particles near rough substrates. Explicit formulas are provided for the case of a sinusoidal deformation of a flat surface. Generic deformations can be treated by superposition. In addition to results for the self-energy, the surface polarization charge is presented as a quadrature. The interaction between an ion and the deformed surface is modified by the change in relative distance as well as by the local curvature of the surface. Solid walls, with a lower dielectric constant than the liquid, repel all ions. We show that the repulsion is reduced by local convexity and enhanced by concavity; dimples are more repulsive than pimples.
Learning self-consistency for deepfake detection

We propose a new method to detect deepfake images using the cue of the source feature inconsistency within the forged images. It is based on the hypothesis that images' distinct source features can be preserved and extracted after going through state-of-the-art deepfake generation processes. We introduce a novel representation learning approach, called pair-wise self-consistency learning (PCL), for training ConvNets to extract these source features and detect deepfake images. It is accompanied by a new image synthesis approach, called inconsistency image generator (I2G), to provide richly annotated training data for PCL. Experimental results on seven popular datasets show that our models improve averaged AUC over the state of the art from 96.45% to 98.05% in the in-dataset evaluation and from 86.03% to 92.18% in the cross-dataset evaluation.
Bayesian Crowdsourcing with Constraints

Crowdsourcing has emerged as a powerful paradigm for efficiently labeling large datasets and performing various learning tasks, by leveraging crowds of human annotators. When additional information is available about the data, constrained or semi-supervised crowdsourcing approaches that enhance the aggregation of labels from human annotators are well motivated. This work deals with constrained crowdsourced classification with instance-level constraints, that capture relationships between pairs of data. A Bayesian algorithm based on variational inference is developed, and its quantifiably improved performance, compared to unsupervised crowdsourcing, is analytically and empirically validated on several crowdsourcing datasets.