cssi/SciSciGPT-SciSciNet huggingface dataset:
Tidal Streams of Intracluster Light

Using N-body simulations, we have modeled the production and evolution of substructures in the intracluster light (ICL) of a simulated galaxy cluster. We use a density-based definition of ICL, where ICL consists of luminous particles which are at low densities, to identify ICL particles and track their evolution. We have implemented a friends-of-friends-type clustering algorithm which finds groups of particles correlated in both position and velocity space to identify substructures in the ICL, hereafter referred to as 'streams'. We find that {approx}40% of the cluster's ICL is generated in the form of these massive (M {>=} 7.0 x 10{sup 8} M{sub sun}), dynamically cold streams. The fraction of the ICL generated in streams is greater early in the cluster's evolution, when galaxies are interacting in the group environment, than later in its evolution when the massive cluster potential has been assembled. The production of streams requires the strong tidal fields associated with close interactions between pairs of galaxies, and is usually associated with merging pairs of galaxies, or fast, close encounters with the cluster's central galaxy. Once streams are formed, they begin to decay as they are disrupted by the tidal field of the cluster. We find that streams havemore » decay timescales which are {approx}1.5 times their dynamical time in the cluster.« less
A CHANDRA OBSERVATION OF THE OBSCURED STAR-FORMING COMPLEX W40

The young stellar cluster illuminating the W40 H II region, one of the nearest massive star-forming regions, has been observed with the ACIS detector on board the Chandra X-ray Observatory. Due to its high obscuration, this is a poorly studied stellar cluster with only a handful of bright stars visible in the optical band, including three OB stars identified as primary excitation sources. We detect 225 X-ray sources, of which 85% are confidently identified as young stellar members of the region. Two potential distances of the cluster, 260 pc and 600 pc, are used in the paper. Supposing the X-ray luminosity function to be universal, it supports a 600 pc distance as a lower limit for W40 and a total population of at least 600 stars down to 0.1 M ☉ under the assumption of a coeval population with a uniform obscuration. In fact, there is strong spatial variation in Ks -band-excess disk fraction and non-uniform obscuration due to a dust lane that is identified in absorption in optical, infrared, and X-ray. The dust lane is likely part of a ring of material which includes the molecular core within W40. In contrast to the likely ongoing star formation in the dust lane, the molecular core is inactive. The star cluster has a spherical morphology, an isothermal sphere density profile, and mass segregation down to 1.5 M ☉. However, other cluster properties, including a 1 Myr age estimate and ongoing star formation, indicate that the cluster is not dynamically relaxed. X-ray diffuse emission and a powerful flare from a young stellar object are also reported.
Introduction to the Special Issue on Sparsity and Regularization Methods

Traditional statistical inference considers relatively small data sets and the corresponding theoretical analysis focuses on the asymptotic behavior of a statistical estimator when the number of samples approaches infinity. However, many data sets encountered in modern applications have dimensionality significantly larger than the number of training data available, and for such problems the classical statistical tools become inadequate. In order to analyze high-dimensional data, new statistical methodology and the corresponding theory have to be developed.
Valid Model-Free Prediction of Future Insurance Claims

Bias resulting from model misspecification is a concern when predicting insurance claims. Indeed, this bias puts the insurer at risk of making invalid or unreliable predictions. A method that could...
Retrieval and Clustering from a 3D Human Database based on Body and Head Shape

In this paper, we describe a framework for similarity based retrieval and clustering from a 3D human database. Our technique is based on both body and head shape representation and the retrieval is based on similarity of both of them. The 3D human database used in our study is the CAESAR anthropometric database which contains approximately 5000 bodies. We have developed a web-based interface for specifying the queries to interact with the retrieval system. Our approach performs the similarity based retrieval in a reasonable amount of time and is a practical approach.
Ferrovolcanism on metal worlds and the origin of pallasites

As differentiated planetesimals cool, their cores can solidify from the outside in1, as evidenced by palaeomagnetic measurements and cooling-rate estimates of iron meteorites2,3. The details of outside-in solidification and fate of residual core melt are poorly understood. For a core primarily composed of iron and nickel alloyed with lighter constituent elements such as sulfur, this inward core growth would probably be achieved by growth of solid iron–nickel dendrites4. Growth of iron–nickel dendrites results in interconnected pockets of residual melt that become progressively enriched in sulfur up to a eutectic composition of 31 wt% sulfur as iron–nickel continues to solidify4. Here, we show that regions of residual sulfur-enriched iron–nickel melt in the core attain sufficient excess pressures to propagate via dykes into the mantle. Thus, core material will intrude into the overlying rocky mantle or possibly even erupt onto the planetesimal’s surface. We refer to these processes collectively as ferrovolcanism. Our calculations show that ferrovolcanic surface eruptions are more likely on bodies with mantles less than 50 km thick. We show that intrusive ferromagmatism can produce pallasites, an enigmatic class of meteorites composed of olivine crystals entrained in a matrix of iron–nickel metal4. Ferrovolcanic eruptions may explain the observations that asteroid 16 Psyche has a bulk density inconsistent with iron meteorites5 yet shows evidence of a metallic surface composition6. Pockets of iron-rich melt within asteroids get progressively enriched in sulfur while the asteroid is cooling, generating excess pressure that can push the melt up to the surface. This ‘ferrovolcanism’ can be the origin of the stony-iron pallasite meteorites and can explain the contradicting results from asteroid 16 Psyche.
N-polar GaN/AlN resonant tunneling diodes

N-polar GaN/AlN resonant tunneling diodes are realized on a single-crystal N-polar GaN bulk substrate by plasma-assisted molecular beam epitaxy growth. The room-temperature current–voltage characteristics reveal a negative differential conductance (NDC) region with a peak tunneling current of 6.8 ± 0.8 kA/cm2 at a forward bias of ∼8 V. Under reverse bias, the polarization-induced threshold voltage is measured at ∼ − 4 V. These resonant and threshold voltages are well explained with the polarization field, which is opposite to that of the metal-polar counterpart, confirming the N-polarity of the resonant tunneling diodes (RTDs). When the device is biased in the NDC-region, electronic oscillations are generated in the external circuit, attesting to the robustness of the resonant tunneling phenomenon. In contrast to metal-polar RTDs, N-polar structures have the emitter on the top of the resonant tunneling cavity. As a consequence, this device architecture opens up the possibility of seamlessly interfacing—via resonant tunneling injection—a wide range of exotic materials with III-nitride semiconductors, providing a route towards unexplored device physics.
On the Evolution of the Ionizing Emissivity of Galaxies and Quasars Required by the Hydrogen Reionization

The average rate of emission of ionizing radiation per unit volume (or emissivity) in the universe can be calculated as the ratio of the intensity of the ionizing background to the mean free path of ionizing photons. The intensity of the background is measured from the mean transmitted flux of the Ly? forest, and the mean free path is measured from the abundance of Lyman limit systems, which has been observed so far up to z = 4. This yields an emissivity that is not larger than seven ionizing photons per Hubble time for each atom in the universe at z = 4, which may reasonably arise from QSOs and star-forming galaxies. In order for the reionization to end by z = 6, and assuming that the clumping factor of ionized gas during the reionization epoch is close to unity, this ionizing comoving emissivity cannot decline from z = 4 up to z ~ 9 by more than a factor 1.5. If the clumping factor were much larger than unity, then the emissivity would need to rapidly increase with redshift. Unless the ionizing emissivity increases substantially from z = 4 to z ~ 10-20, the Thomson optical depth to the cosmic microwave background must be in the range 0.045 < ? < 0.09.
Implementing non-scalar diffraction in Fourier optics via the Braunbek method.

Fourier optics is a powerful and efficient tool for solving many diffraction problems, but relies on the assumption of scalar diffraction theory and ignores the three-dimensional structure and material properties of the diffracting element. Recent experiments of sub-scale starshade external occulters revealed that the inclusion of these physical properties is necessary to explain the observed diffraction at 10−10 of the incident light intensity. Here, we present a methodology for implementing non-scalar diffraction while maintaining the efficiency and ease of standard Fourier optics techniques. Our methodology is based on that of Braunbek, in which the Kirchhoff boundary values are replaced with the exact field in a narrow seam surrounding the edge of the diffracting element. In this paper, we derive the diffraction equations used to implement non-scalar diffraction and outline the computational implementation used to solve those equations. We also provide experimental results that demonstrate our model can replicate the observational signatures of non-scalar diffraction in sub-scale starshades, in effect validating our model to better than 10−10 in relative intensity. We believe this method to be an efficient tool for including additional physics to the models of coronagraphs and other optical systems in which a full electromagnetic solution is intractable.
Differential Equation Axiomatization: The Impressive Power of Differential Ghosts

We prove the completeness of an axiomatization for differential equation invariants. First, we show that the differential equation axioms in differential dynamic logic are complete for all algebraic invariants. Our proof exploits differential ghosts, which introduce additional variables that can be chosen to evolve freely along new differential equations. Cleverly chosen differential ghosts are the proof-theoretical counterpart of dark matter. They create new hypothetical state, whose relationship to the original state variables satisfies invariants that did not exist before. The reflection of these new invariants in the original system then enables its analysis.We then show that extending the axiomatization with existence and uniqueness axioms makes it complete for all local progress properties, and further extension with a real induction axiom makes it complete for all real arithmetic invariants. This yields a parsimonious axiomatization, which serves as the logical foundation for reasoning about invariants of differential equations. Moreover, our results are purely axiomatic, and so the axiomatization is suitable for sound implementation in foundational theorem provers.
CAT(0) groups with specified boundary

We specify exactly which groups can act geometrically on CAT(0) spaces whose visual boundary is homeomorphic to either a circle or a suspension of a Cantor set.
Learning Context-free Languages with Nondeterministic Stack RNNs

We present a differentiable stack data structure that simultaneously and tractably encodes an exponential number of stack configurations, based on Lang’s algorithm for simulating nondeterministic pushdown automata. We call the combination of this data structure with a recurrent neural network (RNN) controller a Nondeterministic Stack RNN. We compare our model against existing stack RNNs on various formal languages, demonstrating that our model converges more reliably to algorithmic behavior on deterministic tasks, and achieves lower cross-entropy on inherently nondeterministic tasks.
A quantified Tauberian theorem for sequences

The main result of this paper is a quantified version of Ingham's Tauberian theorem for bounded vector-valued sequences rather than functions. It gives an estimate on the rate of decay of such a sequence in terms of the behaviour of a certain boundary function, with the quality of the estimate depending on the degree of smoothness this boundary function is assumed to possess. The result is then used to give a new proof of the quantified Katznelson-Tzafriri theorem recently obtained in [21].
Spectrum sharing in cooperative cognitive radio networks: A matching game framework

Dynamic spectrum access allows the unlicensed wireless users (secondary users) to dynamically access the licensed bands from legacy spectrum holders (primary users) either on an opportunistic or a cooperative basis. In this paper, we focus on cooperative spectrum sharing in a wireless network consisting of multiple primary and multiple secondary users. In particular, we study the partner-selection and resource-allocation problems within a matching theory framework, in which the primary and secondary users aim at optimizing their utilities in terms of transmission rate and power consumption. We propose a distributed algorithm to find the solution of the developed matching game that results in a stable matching between the sets of the primary and secondary users. Both analytical and numerical results show that the proposed matching model is a promising approach under which the utility functions of both primary and secondary users are maximized.
Winding branes and persistent currents

A D5 brane winding around a stack of D3 branes can be used as a model of persistent current in a thin superconducting ring, with the number N of D3s corresponding to the number of transverse channels in the ring. We consider, in the large N limit, existence and properties of a gapped superconducting state with a uniform winding number density q. We find that there is a gapped classical solution for any q, no matter how large, but when q is larger than a certain q m the state is unstable with respect to decay by phase slips. We argue that this decay produces strings via a version of the Hanany-Witten effect (in a non-transverse, non-supersymmetric arrangement of branes). This parallels the requirement of quasiparticle production in a clean (disorder-free) wire in field theory of superconductivity.
INSTABILITIES DRIVEN BY THE DRIFT AND TEMPERATURE ANISOTROPY OF ALPHA PARTICLES IN THE SOLAR WIND

We investigate the conditions under which parallel-propagating Alfven/ion-cyclotron (A/IC) waves and fast-magnetosonic/whistler (FM/W) waves are driven unstable by the differential flow and temperature anisotropy of alpha particles in the solar wind. We focus on the limit in which w ∥α 0.25v A, where w ∥α is the parallel alpha-particle thermal speed and v A is the Alfven speed. We derive analytic expressions for the instability thresholds of these waves, which show, e.g., how the minimum unstable alpha-particle beam speed depends upon w ∥α/v A, the degree of alpha-particle temperature anisotropy, and the alpha-to-proton temperature ratio. We validate our analytical results using numerical solutions to the full hot-plasma dispersion relation. Consistent with previous work, we find that temperature anisotropy allows A/IC waves and FM/W waves to become unstable at significantly lower values of the alpha-particle beam speed U α than in the isotropic-temperature case. Likewise, differential flow lowers the minimum temperature anisotropy needed to excite A/IC or FM/W waves relative to the case in which U α = 0. We discuss the relevance of our results to alpha particles in the solar wind near 1 AU.
Canonical idempotents of multiplicity-free families of algebras

Any multiplicity-free family of finite dimensional algebras has a canonical complete set of of pairwise orthogonal primitive idempotents in each level. We give various methods to compute these idempotents. In the case of symmetric group algebras over a field of characteristic zero, the set of canonical idempotents is precisely the set of seminormal idempotents constructed by Young. As an example, we calculate the canonical idempotents for semisimple Brauer algebras.
Optical cavity resonator in an expanding universe

We study the cosmological evolution of frequency of a standing electromagnetic wave in a resonant optical cavity placed to the expanding manifold described by the Robertson–Walker metric. Because of the Einstein principle of equivalence (EEP), one can find a local coordinate system (a local freely falling frame), in which spacetime is locally Minkowskian. However, due to the conformal nature of the Robertson–Walker metric the conventional transformation to the local inertial coordinates introduces ambiguity in the physical interpretation of the local time coordinate, $$X^0$$ . Therefore, contrary to a common-sense expectation, a straightforward implementation of EEP alone does not allow us to unambiguously decide whether atomic clocks based on quantum transitions of atoms, ticks at the same rate as the clocks based on electromagnetic modes of a cavity. To resolve this ambiguity we have to analyse the cavity rigidity and the oscillation of its electromagnetic modes in an expanding universe by employing the full machinery of the Maxwell equations irrespectively of the underlying theory of gravity. We proceed in this way and found out that the size of the cavity and the electromagnetic frequency experience an adiabatic drift in conformal (unphysical) coordinates as the universe expands in accordance with the Hubble law. We set up the oscillation equation for the resonant electromagnetic modes, solve it by the WKB approximation, and reduce the coordinate-dependent quantities to their counterparts measured by a local observer who counts time with atomic clock. The solution shows that there is a perfect mutual cancellation of the adiabatic drift of cavity’s frequency by space transformation to local coordinates and the time counted by the clocks based on electromagnetic modes of cavity has the same rate as that of atomic clocks. We conclude that if general relativity is correct and the local expansion of space is isotropic there should be no cosmological drift of frequency of a standing electromagnetic wave oscillating in the cavity resonator as compared to the frequency of atomic clocks. Continuous comparison of the frequency of the optical cavity resonator against that of atomic clock yields a powerful null test of the local isotropy of the Hubble expansion and the Einstein equivalence principle in cosmology.
Descendents on local curves: rationality

We study the stable pairs theory of local curves in 3-folds with descendent insertions. The rationality of the partition function of descendent invariants is established for the full local curve geometry (equivariant with respect to the scaling 2-torus) including relative conditions and odd degree insertions for higher genus curves. The capped 1-leg descendent vertex (equivariant with respect to the 3-torus) is also proven to be rational. The results are obtained by combining geometric constraints with a detailed analysis of the poles of the descendent vertex.
COVID-19 Misinformation Prophylaxis: Protocol for a Randomized Trial of a Brief Informational Intervention.

Background: As the COVID-19 pandemic continues to affect life in the United States, the important role of nonpharmaceutical preventive behaviors (such as wearing a face mask) in reducing the risk of infection has become clear. During the pandemic, researchers have observed the rapid proliferation of misinformed or inconsistent narratives about COVID-19. There is growing evidence that such misinformed narratives are associated with various forms of undesirable behavior (eg, burning down cell towers). Furthermore, individuals’ adherence to recommended COVID-19 preventive guidelines has been inconsistent, and such mandates have engendered opposition and controversy. Recent research suggests the possibility that trust in science and scientists may be an important thread to weave throughout these seemingly disparate components of the modern public health landscape. Thus, this paper describes the protocol for a randomized trial of a brief, digital intervention designed to increase trust in science. Objective: The objective of this study is to examine whether exposure to a curated infographic can increase trust in science, reduce the believability of misinformed narratives, and increase the likelihood to engage in preventive behaviors. Methods: This is a randomized, placebo-controlled, superiority trial comprising 2 parallel groups. A sample of 1000 adults aged ≥18 years who are representative of the population of the United States by gender, race and ethnicity, and age will be randomly assigned (via a 1:1 allocation) to an intervention or a placebo-control arm. The intervention will be a digital infographic with content based on principles of trust in science, developed by a health communications expert. The intervention will then be both pretested and pilot-tested to determine its viability. Study outcomes will include trust in science, a COVID-19 narrative belief latent profile membership, and the likelihood to engage in preventive behaviors, which will be controlled by 8 theoretically selected covariates. Results: This study was funded in August 2020, approved by the Indiana University Institutional Review Board on September 15, 2020, and prospectively registered with ClinicalTrials.gov. Conclusions: COVID-19 misinformation prophylaxis is crucial. This proposed experiment investigates the impact of a brief yet actionable intervention that can be easily disseminated to increase individuals’ trust in science, with the intention of affecting misinformation believability and, consequently, preventive behavioral intentions. Trial Registration: ClinicalTrials.gov NCT04557241; https://clinicaltrials.gov/ct2/show/NCT04557241
Usage Bibliometrics as a Tool to Measure Research Activity.

Measures for research activity and impact have become integral ingredients in the assessment of a wide range of entities (individual researchers, organizations, institutions, regions, disciplines). Traditional bibliometric indicators, like publication- and citation-based indicators, provide an essential part of this picture, but cannot describe the complete picture. Since reading scholarly publications is an essential part of the research lifecycle, it is only natural to introduce measures for this activity in attempts to quantify the efficiency, productivity and impact of an entity. Citations and reads are significantly different signals, so taken together, they provide a more complete picture of research activity. Most scholarly publications are now accessed online, making the study of reads and read patterns possible. Clickstream logs allow us to follow information access by the entire research community in real time. Publication and citation datasets just reflect activity by authors. In addition, download statistics, derived from these clickstreams, will help us identify publications with significant impact, but which do not attract many citations. Clickstream signals are arguably more complex than, say, citation signals. For one, they are a superposition of different classes of readers. Systematic downloads by crawlers also contaminate the signal, as does random browsing behavior. We will discuss the complexities associated with clickstream data and how, with proper filtering, statistically significant relations and conclusions can be inferred from download statistics. We will describe how download statistics can be used to describe research activity at different levels of aggregation, ranging from organizations to countries. These statistics show a strong correlation with socioeconomic indicators , like the gross domestic product ( ). A comparison will be made with traditional bibliometric indicators. Since we will be using clickstream data from the Astrophysics Data System ( ), we will argue that astronomy is representative for more general trends.
A cosmological Slavnov-Taylor identity

We develop a method for treating the consistency relations of inflation that includes the full time-evolution of the state. This approach relies only on the symmetries of the inflationary setting, in particular a residual conformal symmetry in the spatial part of the metric, along with general properties which hold for any quantum field theory. As a result, the consistency relations that emerge, which are essentially the Slavnov-Taylor identities associated with this residual conformal symmetry, apply very generally: they are true of the full Green's functions, hold largely independently of the particular inflationary model, and can be used for arbitrary states. We illustrate these techniques by showing the form assumed by the standard consistency relation between the two and three-point functions for the primordial scalar fluctuations when they are in a Bunch-Davies state. But because we have included the full evolution of the state, this approach works for a general initial state as well and does not need to have assumed that inflation began in the Bunch-Davies state. We explain how the Slavnov-Taylor identity is modified for these more general states.
Weak closures and derived sets in dual Banach spaces

The main results of the paper: \textbf{(1)} The dual Banach space contains a linear subspace such that the set of all limits of weak convergent bounded nets in is a proper norm-dense subset of if and only if is a non-quasi-reflexive Banach space containing an infinite-dimensional subspace with separable dual. \textbf{(2)} Let be a non-reflexive Banach space. Then there exists a convex subset such that (the latter denotes the weak closure of ). \textbf{(3)} Let be a quasi-reflexive Banach space and be an absolutely convex subset. Then .
Macroscopic traversable wormholes with zero tidal forces inspired by noncommutative geometry

This paper addresses the following issues: (1) the possible existence of macroscopic traversable wormholes, given a noncommutative-geometry background and (2) the possibility of allowing zero tidal forces, given a known density. It is shown that whenever the energy density describes a classical wormhole, the resulting solution is incompatible with quantum-field theory. If the energy density originates from noncommutative geometry, then zero tidal forces are allowed. Also attributable to the noncommutative geometry is the violation of the null energy condition. The wormhole geometry satisfies the usual requirements, including asymptotic flatness.
ON THE SUMS OF TWO CUBES

We solve the equation f(x, y)3 + g(x, y)3 = x3 + y3 for homogeneous f, g ∈ ℂ(x, y), completing an investigation begun by Viete in 1591. The usual addition law for elliptic curves and composition give rise to two binary operations on the set of solutions. We show that a particular subset of the set of solutions is ring isomorphic to ℤ[e2πi/3].
PERSONAL HISTORY OF MY ENGAGEMENT WITH CUPRATE SUPERCONDUCTIVITY, 1986–2010

Six months ago, I was asked to write a personal history of my engagement with the high-Tc problem of the cuprate superconductors, in a rather informal and autobiographical style. As the work proceeded, I realized that it was impossible and would have been dishonest to separate out my rather amusing but seminal early fumblings from the complete restructuring of the problem which I have achieved during the past decade. But the result became considerably too long, by over half, for its intended recipient. The assignment had left me with no obligation to deal with all the fascinating but irrelevant phenomenology which I had more or less instinctively ignored on my way, but that feature also fails to endear the article to any conceivable editorial board containing knowledgeable experts on the subject. Also, their purpose was for it to serve as an "introduction to the more technical debates", but its message is that almost all of these are not relevant. They are not, on the whole, focused on achieving understanding of the crucial experimental anomalies, many, if not most, of which are now understood. The key to the problem is a new method of dealing with the constrained Hilbert space which follows from the necessity of Gutzwiller projection.
Collective vibrations of confined levitating droplets

Experiments are performed exploring the dynamics and stability of quasi-one-dimensional lattices of self-propelled millimetric droplets bouncing on a vertically vibrating liquid bath and confined to an annular ring. Depending on the droplet spacing, instability of the lattice may take the form of either out-of-phase oscillations or a striking solitarylike wave. Our results offer a new macroscopic platform to study collective phenomena and emergent structures in the burgeoning field of active and driven matter.
Combinatorial proofs in bordered Heegaard Floer homology

Using bordered Floer theory, we give a combinatorial construction and proof of invariance for the hat version of Heegaard Floer homology. As a part of the proof, we also establish combinatorially the invariance of the linear-categorical representation of the strongly-based mapping class groupoid given by the same theory.
Perturbing Inputs to Prevent Model Stealing

We show how perturbing inputs to machine learning services (ML-service) deployed in the cloud can protect against model stealing attacks. In our formulation, there is an ML-service that receives inputs from users and returns the output of the model. There is an attacker that is interested in learning the parameters of the ML-service. We use the linear and logistic regression models to illustrate how strategically adding noise to the inputs fundamentally alters the attacker’s estimation problem. We show that even with infinite samples, the attacker would not be able to recover the true model parameters. We focus on characterizing the trade-off between the error in the attacker’s estimate of the parameters with the error in the ML-service’s output.
New solutions with accelerated expansion in string theory

We present concrete solutions with accelerated expansion in string theory, requiring a small, tractable list of stress energy sources. We explain how this construction (and others in progress) evades previous no go theorems for simple accelerating solutions. Our solutions respect an approximate scaling symmetry and realize discrete sequences of values for the equation of state, including one with an accumulation point at w = −1 and another accumulating near w = −1/3 from below. In another class of models, a density of defects generates scaling solutions with accelerated expansion. We briefly discuss potential applications to dark energy phenomenology, and to holography for cosmology.
Complexity in surfaces of densest packings for families of polyhedra

The maximum packing density of particles is greatly affected by their shape, an important issue in nanotechnology, biology, and industry that is nevertheless poorly understood mathematically. This comprehensive study takes an analytical and computational approach to calculating the highest-known packing density of over 55,000 related shapes, leading to new guidelines on how to prepare particles for maximum packing efficiency.
Descartes’ rule of signs and the identifiability of population demographic models from genomic variation data

The sample frequency spectrum (SFS) is a widely-used summary statistic of genomic variation in a sample of homologous DNA sequences. It provides a highly efficient dimensional reduction of large-scale population genomic data and its mathematical dependence on the underlying population demography is well understood, thus enabling the development of efficient inference algorithms. However, it has been recently shown that very different population demographies can actually generate the same SFS for arbitrarily large sample sizes. Although in principle this nonidentifiability issue poses a thorny challenge to statistical inference, the population size functions involved in the counterexamples are arguably not so biologically realistic. Here, we revisit this problem and examine the identifiability of demographic models under the restriction that the population sizes are piecewise-defined where each piece belongs to some family of biologically-motivated functions. Under this assumption, we prove that the expected SFS of a sample uniquely determines the underlying demographic model, provided that the sample is sufficiently large. We obtain a general bound on the sample size sufficient for identifiability; the bound depends on the number of pieces in the demographic model and also on the type of population size function in each piece. In the cases of piecewise-constant, piecewise-exponential and piecewise-generalized-exponential models, which are often assumed in population genomic inferences, we provide explicit formulas for the bounds as simple functions of the number of pieces. Lastly, we obtain analogous results for the "folded" SFS, which is often used when there is ambiguity as to which allelic type is ancestral. Our results are proved using a generalization of Descartes' rule of signs for polynomials to the Laplace transform of piecewise continuous functions.
A finiteness theorem for specializations of dynatomic polynomials

Let $t$ and $x$ be indeterminates, let $\phi(x)=x^2+t\in\mathbb Q(t)[x]$, and for every positive integer $n$ let $\Phi_n(t,x)$ denote the $n^{\text{th}}$ dynatomic polynomial of $\phi$. Let $G_n$ be the Galois group of $\Phi_n$ over the function field $\mathbb Q(t)$, and for $c\in\mathbb Q$ let $G_{n,c}$ be the Galois group of the specialized polynomial $\Phi_n(c,x)$. It follows from Hilbert's irreducibility theorem that for fixed $n$ we have $G_n\cong G_{n,c}$ for every $c$ outside a thin set $E_n\subset\mathbb Q$. By earlier work of Morton (for $n=3$) and the present author (for $n=4$), it is known that $E_n$ is infinite if $n\le 4$. In contrast, we show here that $E_n$ is finite if $n\in\{5,6,7,9\}$. As an application of this result we show that, for these values of $n$, the following holds with at most finitely many exceptions: for every $c\in\mathbb Q$, more than $81\%$ of prime numbers $p$ have the property that the polynomial $x^2+c$ does not have a point of period $n$ in the $p$-adic field $\mathbb Q_p$.
Transient pulses from exploding primordial black holes as a signature of an extra dimension

An evaporating black hole in the presence of an extra spatial dimension would undergo an explosive phase of evaporation. We show that such an event, involving a primordial black hole, can produce a detectable, distinguishable electromagnetic pulse, signaling the existence of an extra dimension of size L~10−18–10−20 m. We derive a generic relationship between the Lorentz factor of a pulse-producing 'fireball' and the TeV energy scale. For an ordinary toroidally compactified extra dimension, transient radio-pulse searches probe the electroweak energy scale (~0.1 TeV), enabling comparison with the Large Hadron Collider.
Use of checkpoint-restart for complex HEP software on traditional architectures and Intel MIC

Process checkpoint-restart is a technology with great potential for use in HEP workflows. Use cases include debugging, reducing the startup time of applications both in offline batch jobs and the High Level Trigger, permitting job preemption in environments where spare CPU cycles are being used opportunistically and efficient scheduling of a mix of multicore and single-threaded jobs. We report on tests of checkpoint-restart technology using CMS software, Geant4-MT (multi-threaded Geant4), and the DMTCP (Distributed Multithreaded Checkpointing) package. We analyze both single- and multi-threaded applications and test on both standard Intel x86 architectures and on Intel MIC. The tests with multi-threaded applications on Intel MIC are used to consider scalability and performance. These are considered an indicator of what the future may hold for many-core computing.
Axioms for a local Reidemeister trace in fixed point and coincidence theory on differentiable manifolds

We give axioms which characterize the local Reidemeister trace for orientable differentiable manifolds. The local Reidemeister trace in fixed point theory is already known, and we provide both uniqueness and existence results for the local Reidemeister trace in coincidence theory.
Analysis of the Factors Affecting Violent Crime Rates in the US

The goal of this study is to analyze the factors affecting violent crime rates in the US. It is hypothesized that an increase in the gun ownership rate tends to increase violent crimes in the US. It is hypothesized that urban areas in the US tend to have more violent crimes than rural areas. An OLS regression model is formulated using cross-sectional data set across 50 states and the District of Columbia for the year 2019. The endogenous variable is the violent crime rates per 100,000 inhabitants across 50 states and the District of Columbia. The independent variables used in the OLS regression model are population density per square mile, unemployment rate, percentage of the population living in poverty, and gun ownership rate. The four exogenous variables that are found to be statistically significant are gun ownership, unemployment rate, population density per square mile, and percentage of population living in property. An attempt is also made to formulate strategies that would help in reducing violent crime rates in the US.
Fan-out and fan-in properties of superconducting neuromorphic circuits

Neuromorphic computing has the potential to further the success of software-based artificial neural networks (ANNs) by designing hardware from a different perspective. Current research in neuromorphic hardware targets dramatic improvements to ANN performance by increasing energy efficiency and speed of operation and even seeks to extend the utility of ANNs by natively adding functionality such as spiking operation. One promising neuromorphic hardware platform is based on superconductive electronics, which has the potential to incorporate all of these advantages at the device level in addition to offering the potential of near lossless communications both within the neuromorphic circuits and between disparate superconductive chips. Here, we explore one of the fundamental brain-inspired architecture components, the fan-in and fan-out as realized in superconductive circuits based on Josephson junctions. From our calculations and WRSPICE simulations, we find that the fan-out should be limited only by junction count and circuit size limitations, and we demonstrate results in simulation at a level of 1-to-10 000, similar to that of the human brain. We find that fan-in has more limitations, but a fan-in level on the order of a few 100-to-1 should be achievable based on current technology. We discuss our findings and the critical parameters that set the limits on fan-in and fan-out in the context of superconductive neuromorphic circuits.
Dynamic price relationships and price discovery among cheese markets

The United States (U.S.) cheese sector has been steadily growing throughout the years. Since 1980, U.S. consumers have doubled their annual consumption of cheese, currently at about 37.9 lbs. per c...
CS-NLP Team at SemEval-2020 Task 4: Evaluation of State-of-the-art NLP Deep Learning Architectures on Commonsense Reasoning Task

In this paper, we investigate a commonsense inference task that unifies natural language understanding and commonsense reasoning. We describe our attempt at SemEval-2020 Task 4 competition: Commonsense Validation and Explanation (ComVE) challenge. We discuss several state-of-the-art deep learning architectures for this challenge. Our system uses prepared labeled textual datasets that were manually curated for three different natural language inference subtasks. The goal of the first subtask is to test whether a model can distinguish between natural language statements that make sense and those that do not make sense. We compare the performance of several language models and fine-tuned classifiers. Then, we propose a method inspired by question/answering tasks to treat a classification problem as a multiple choice question task to boost the performance of our experimental results (96.06%), which is significantly better than the baseline. For the second subtask, which is to select the reason why a statement does not make sense, we stand within the first six teams (93.7%) among 27 participants with very competitive results. Our result for last subtask of generating reason against the nonsense statement shows many potentials for future researches as we applied the most powerful generative model of language (GPT-2) with 6.1732 BLEU score among first four teams. .
Simplifying Multiple-Statement Reductions with the Polyhedral Model

A Reduction â€“ an accumulation over a set of values, using an associative and commutative operator â€“ is a common computation in many numerical computations, including scientific computations, machine learning, computer vision, and financial analytics.
The feasible region of hypergraphs

Abstract Let F be a family of r-uniform hypergraphs. The feasible region Ω ( F ) of F is the set of points ( x , y ) in the unit square such that there exists a sequence of F -free r-uniform hypergraphs whose shadow density approaches x and whose edge density approaches y. The feasible region provides a lot of combinatorial information, for example, the supremum of y over all ( x , y ) ∈ Ω ( F ) is the Turan density π ( F ) , and Ω ( ∅ ) gives the Kruskal-Katona theorem. We undertake a systematic study of Ω ( F ) , and prove that Ω ( F ) is completely determined by a left-continuous almost everywhere differentiable function; and moreover, there exists an F for which this function is not continuous. We also extend some old related theorems. For example, we generalize a result of Fisher and Ryan to hypergraphs and extend a classical result of Bollobas by almost completely determining the feasible region for cancellative triple systems.
Policy Implications of the Common Ownership Debate

Empirical findings that common ownership is associated with anticompetitive outcomes including higher prices raise questions about possible policy responses. This comment evaluates the major propos...
Function over Form: Bringing the Fixation Requirement into the Modern Era

This Article examines the ways that contemporary creativity challenges copyright’s fixation requirement. In this Article, we identify concrete problems with the fixation requirement, both practically and in light of the fundamental purpose and policy behind copyright law, and argue for a change that would amend the fixation requirement to better function in the modern era.Specifically, we conclude that a fair appraisal of the justifications for the fixation requirement provides little, if any, rationale for fixation except to the extent that fixation helps to separate idea from expression in determining the “metes and bounds” of creative expression. Recent case law analyzing the transitory works exclusion in particular demonstrates that this component of the fixation requirement has become an ineffective demarcation of what it means to fix a work in the modern era and provides little guidance for statutory interpretation. We reason that dropping the transitory duration exclusion for copyrightability would enable fixation to serve its essential purpose while not discriminating against important strains of contemporary creativity. Furthermore, removing the transitory works exclusion would better equip copyright law to reflect the purposes of the Intellectual Property Clause in the U.S. Constitution. Despite these considerations, if dropping the exclusion for transitory works is not practically feasible, we argue that it is nevertheless desirable to allow a flexible interpretation of statutory language in light of the purposes of copyright and allow transitory works to come into a safe harbor from the general fixation requirement for copyrightability under the aegis of the Visual Artists Rights Act.
Reconciling Federal and State Interests in Securities Regulation in the United States and Europe

Securities law in the United States is found primarily in the federal securities laws administered by the Securities and Exchange Commission and interpreted by the courts. The federal securities laws were preceded by state securities laws administered by state securities commissions and stock exchange regulations and listing requirements. Although key aspects of state securities regulation have been preempted, other aspects remain in tact. Stock exchange requirements now are part of the federal securities laws. Further, corporation law is primarily state law, even though it is sometimes overriden by the federal securities laws. All of this regulation results in a fair amount of regulatory competititon that frequently is difficult to reconcile. Europe is struggling with similar problems in reconciling federal and state law and regulation concerning capital markts and public companies. This article outlines the framework and historical development of securities law in the United States and Europe and the long term trend toward federal regulation despite some countervailing actions by local interests. It also discusses the tension between federal and state interests in takeover law as an example of an effort to reconcile competing regulatory goals. One of the author's conclusions is that politics and economic history are more important than theory in explaining the dominance of federal over state regulation. Further, regulatory competition is not an appropriate method for making investor protection the reconciling principle between federal and state interests.
Pricing with Limited Knowledge of Demand

How should a firm price a new product for which little is known about demand? We propose a pricing rule that can be used if the firm can estimate (even roughly) the maximum price it can charge and still expect to sell some units, and the firm need not know in advance the quantity it will sell. The rule is simple: Set price as though the demand curve were linear. We show that if the true demand curve is one of many commonly used demand functions, or even a more complex function, and if marginal cost is known and constant, the firm can expect its profit to be close to what it would earn if it knew the true demand curve. We derive analytical performance bounds for a variety of demand functions, calculate expected profit performance for randomly generated demand curves, and evaluate the welfare implications of our pricing rule.
Torture in Counterterrorism: Agency Incentives and Slippery Slopes

Abstract We develop a counterterrorism model to analyze the effects of allowing a government agency to torture suspects when evidence of terrorist involvement is strong. We find that legalizing torture in strong-evidence cases has offsetting effects on agency incentives to counter terrorism by means other than torture. It lowers these incentives because the agency may come to rely on torture to avert attacks. However, it also increases these incentives because other efforts may increase the probability of having strong enough evidence to warrant the use of torture. Legalizing torture in strong-evidence cases is more likely to reduce non-torture efforts if these efforts are more effective at stopping attacks and less effective at turning up strong evidence when the suspect is guilty. If it reduces non-torture efforts, it can reduce security and is more likely to do so if the attack threat is higher. Moreover, if torture is used in strong-evidence cases even if torture is banned, legalizing torture in strong-evidence cases necessarily reduces security if it reduces non-torture efforts. Lastly, it can increase incentives to torture even in weak-evidence cases—a slippery slope.