cssi/SciSciGPT-SciSciNet huggingface dataset:
Laser-Cooling-Assisted Mass Spectrometry

Mass spectrometry is a key analytical tool in many disciplines, as it provides accurate identification of unknown chemical components in complex mixtures. The authors demonstrate that using laser cooling significantly increases the phase-space density of this assay, improving both mass resolution and detection limits by better than an order of magnitude.
Magnetic reconnection with null and X-points

Null and X-points are not themselves directly important to magnetic reconnection because distinguishable field lines do not approach them closely. Even in a collision-free plasma, magnetic field lines that approach each other on a scale c / ω p e become indistinguishable during an evolution. What is important is the different regions of space that can be explored by magnetic field lines that pass in the vicinity of null and X-points. Traditional reconnection theories made the assumption that the reconnected magnetic flux must be dissipated or diffused by an electric field. This assumption is false in three dimensional systems because an ideal evolution can cause magnetic field lines that cover a large volume to approach each other within the indistinguishability scale c / ω p e. When the electron-ion collision time τei is short compared to the evolution time of the magnetic field τev, the importance of c / ω p e is replaced by the resistive time scale τ η = ( η / μ 0 ) L 2 with L being the system scale. The magnetic Reynolds number R m ≡ τ η / τ e v is enormous in many reconnection problems of interest. Magnetic flux diffusion implies the current density required for reconnection to compete with evolution scales as Rm, while flux mixing implies the required current density to compete scales as ln R m.
Good frames in the Hart–Shelah example

For a fixed natural number $$n \ge 1$$ , the Hart–Shelah example is an abstract elementary class (AEC) with amalgamation that is categorical exactly in the infinite cardinals less than or equal to $$\aleph _{n}$$ . We investigate recently-isolated properties of AECs in the setting of this example. We isolate the exact amount of type-shortness holding in the example and show that it has a type-full good $$\aleph _{n - 1}$$ -frame which fails the existence property for uniqueness triples. This gives the first example of such a frame. Along the way, we develop new tools to build and analyze good frames.
Flexible covariate-adjusted exact tests of randomized treatment effects with application to a trial of HIV education

The primary goal of randomized trials is to compare the effects of different interventions on some outcome of interest. In addition to the treatment assignment and outcome, data on baseline covariates, such as demographic characteristics or biomarker measurements, are typically collected. Incorporating such auxiliary co-variates in the analysis of randomized trials can increase power, but questions remain about how to preserve type I error when incorporating such covariates in a flexible way, particularly when the number of randomized units is small. Using the Young Citizens study, a cluster randomized trial of an educational intervention to promote HIV awareness, we compare several methods to evaluate intervention effects when baseline covariates are incorporated adaptively. To ascertain the validity of the methods shown in small samples, extensive simulation studies were conducted. We demonstrate that randomization inference preserves type I error under model selection while tests based on asymptotic theory may yield invalid results. We also demonstrate that covariate adjustment generally increases power, except at extremely small sample sizes using liberal selection procedures. Although shown within the context of HIV prevention research, our conclusions have important implications for maximizing efficiency and robustness in randomized trials with small samples across disciplines.
Reply to comment on ‘Kinetic theory of the presheath and the Bohm criterion’

In his comment, Riemann defends the conventional kinetic Bohm criterion (KBC) on the basis that the underlying approximations become rigorous in the limit ?D/l???0, where ?D is the Deybe length and l is a collision length scale for the dominant collision process. Here, we expand on our previous arguments showing that the basic assumptions for the justified use of the conventional KBC are typically not satisfied in laboratory plasmas. We corroborate our argument with experimental data, as well as data from numerical simulations, showing that the conventional criterion is violated in common situations. In contrast, a formulation based on positive velocity moments of the kinetic equation provides a criterion that both agrees with the experimental data and reduces to the traditional expectations from fluid theory in the appropriate limit.
The weight in a Serre-type conjecture for tame $n$-dimensional Galois representations

We formulate a Serre-type conjecture for n-dimensional Galois representations that are tamely ramified at p. The weights are predicted using a representation-theoretic recipe. For n=3, some of these weights were not predicted by the previous conjecture of Ash, Doud, Pollack, and Sinnott. Computational evidence for these extra weights is provided by calculations of Doud and Pollack. We obtain theoretical evidence for n=4 by using automorphic inductions of Hecke characters
X-Ray Observations of Stellar Clusters Near the Galactic Center

We report the first detection of X-ray emission from the Quintuplet star cluster and compare its X-ray emission to that of the Arches star cluster. Four point sources are significantly detected near the core of the Quintuplet cluster with a total absorption-corrected luminosity of � 1 ; 10 33 ergs s � 1 . Diffuse, thermal emission is also detected near the core of the Quintuplet cluster with an absorption-corrected luminosity of � 1 ; 10 34 ergs s � 1 . We analyze the diffuse and pointlike emission from the Arches and Quintuplet clusters and discuss the possibility that they are host to cluster wind outflows. We also present the results of our search for X-ray emission from candidate star clusters in the Galactic center (GC) region. We use extinction estimated by near-IR colors and X-ray spectral fits, as well as other IR properties, to determine if the candidate clusters are new GC star clusters. We find that three of the six candidate clusters toward the GC are likely foreground clusters, two of the candidate clusters are not detected in the X-ray data but have near-IR extinctions consistent with a GC location, and one of the candidate clusters has X-ray and near-IR extinctions consistent with being in the GC. The X-ray and IR emission from the candidate clusters is compared to the known massive GC star clusters. Subject headings: Galaxy: center — Galaxy: open clusters and associations: individual (Arches, Quintuplet) — stars: Wolf-Rayet — X-rays: galaxies: clusters
The Magnetoviscous-thermal Instability

Accretion flows onto underluminous black holes, such as Sagittarius A* at the center of our galaxy, are dilute (mildly collisional to highly collisionless), optically thin, and radiatively inefficient. Therefore, the accretion properties of such dilute flows are expected to be modified by their large viscosities and thermal conductivities. Second, turbulence within these systems needs to transport angular momentum as well as thermal energy generated through gravitational infall outward in order to allow accretion to occur. This is in contrast to classical accretion flows, in which the energy generated through accretion down a gravitational well is locally radiated. In this paper, using an incompressible fluid treatment of an ionized gas, we expand on previous research by considering the stability properties of a magnetized rotating plasma wherein the thermal conductivity and viscosity are not negligible and may be dynamically important. We find a class of MHD instabilities that can transport angular momentum and thermal energy outward. They are plausible candidates to describe accretion in radiatively inefficient accretion flows. We finish by discussing the implications for analytic models and numerical MHD simulations of mildly dilute or collisionless astrophysical plasmas, and immediate directions for further research.
Energy in Gravitation and Noether's Theorems

I exhibit the conflicting roles of Noether's two great theorems in defining conserved quantities, especially energy in general relativity and its extensions: it is the breaking of coordinate invariance through boundary conditions that removes the barrier her second theorem otherwise poses to the applicability of her first. There is nothing new here, except the emphasis that general must be broken down to special relativity in a special, but physically natural, way in order for Poincare or other global groups such as (A)dS to 're-'emerge.
Expected value of the one-dimensional earth mover’s distance

From a combinatorial point of view, we consider the Earth Mover's Distance (EMD) associated with a metric measure space. The specific case considered is deceptively simple: Let the finite set [n] = {1,...,n} be regarded as a metric space by restricting the usual Euclidean distance on the real numbers. The EMD is defined on ordered pairs of probability distributions on [n]. We provide an easy method to compute a generating function encoding the values of EMD in its coefficients, which is related to the Segre embedding from projective algebraic geometry. As an application we use the generating function to compute the expected value of EMD in this one-dimensional case. The EMD is then used in clustering analysis for a specific data set.
Decentralized Schemes With Overlap for Solving Graph-Structured Optimization Problems

We present a new algorithmic paradigm for the decentralized solution of graph-structured optimization problems that arise in the estimation and control of network systems. A key and novel design concept of the proposed approach is that it uses overlapping subdomains to promote and accelerate convergence. We show that the algorithm converges if the size of the overlap is sufficiently large and that the convergence rate improves exponentially with the size of the overlap. The proposed approach provides a bridge between fully decentralized and centralized architectures and is flexible in that it enables the implementation of asynchronous schemes, handling of constraints, and balancing of computing, communication, and data privacy needs. The proposed scheme is tested in an estimation problem for a 9241-node power network and we show that it outperforms the alternating direction method of multipliers.
Quantum transport in 3D Weyl semimetals: Is there a metal-insulator transition?

We calculate the transport properties of three-dimensional Weyl fermions in a disordered environment. The resulting conductivity depends only on the Fermi energy and the scattering rate. First we study the conductivity at the spectral node for a fixed scattering rate and obtain a continuous transition from an insulator at weak disorder to a metal at stronger disorder. Within the self-consistent Born approximation the scattering rate depends on the Fermi energy. Then it is crucial that the limits of the conductivity for a vanishing Fermi energy and a vanishing scattering rate do not commute. As a result, there is also metallic behavior in the phase with vanishing scattering rate and only a quantum critical point remains as an insulating phase. The latter turns out to be a critical fixed point in terms of a renormalization-group flow.
LOWER LIMITS ON ULTRAHIGH-ENERGY COSMIC RAY AND JET POWERS OF TeV BLAZARS

Lower limits on the power emitted in ultrahigh-energy cosmic rays (UHECRs), which are assumed to be protons with energy 1017-1020 eV, are derived for TeV blazars with the assumption that the observed TeV γ-rays are generated due to interactions of these protons with cosmic microwave photons. The limits depend on the spectrum of the injected UHECR protons. While for a –2.2 injection spectrum the lower limits on the powers emitted in UHECRs by 1ES 0229+200, 1ES 1101–232, and 1ES 0347–121 are lower than their respective synchrotron luminosities (~1046 erg s–1), in the case of 1ES 1426+428 it exceeds the corresponding synchrotron luminosity by up to an order of magnitude. The proposed Auger North Observatory should be able to detect 4 × 1019 eV cosmic-ray (CR) protons from 1ES 1426+428 within a few years of operation and test the TeV γ-ray production model by UHECR energy losses while propagating along the line of sight or constrain the intergalactic magnetic field to be larger than ~10–16 G in case of no detection. The lower limits on the apparent-isotropic jet power from accelerated 1010-1020 eV proton spectra in the blazar jet is of the order of the Eddington luminosity of a 109 M ☉ black hole for a CR injection spectrum –2.2 or harder for all blazars considered except for 1ES 1426+428. In the case of the latter, the apparent-isotropic jet power exceeds the Eddington luminosity by an order of magnitude. For an injection spectrum softer than –2.2, as is required to fit the observed CR data above ~1017-1018 eV, the Eddington luminosity is exceeded by the lower limits on the jet power for all blazars considered.
Fractional electrical dimensionality in the spin solid phase of artificial honeycomb lattice

Two-dimensional artificial magnetic honeycomb lattices are at the forefront of research on unconventional magnetic materials. Among the many emergent magnetic phases that are predicted to arise as a function of temperature, the low temperature spin solid phase with zero magnetization and entropy is of special importance. Here, we report an interesting perspective to the consequence of spin solid order in an artificial honeycomb lattice of ultra-small connected elements using electrical dimensionality analysis. At low temperature, T ≤ 30 K, the system exhibits a very strong insulating characteristic. The electrical dimensionality analysis of the experimental data reveals a fractional dimensionality of d = 0.6(0.04) in the spin solid phase of honeycomb lattice at low temperature. The much smaller electrical dimension in the spin solid phase, perhaps, underscores the strong insulating behavior in this system. Also, the fractional dimensionality in an otherwise two-dimensional system suggests a non-surface-like electrical transport at low temperature in an artificial honeycomb lattice.
Matroids: A Macaulay2 package

We give an overview of the Macaulay2 package Matroids, which contains functionality to create and compute with matroids. Examples highlighting the use of all major functions in the package are provided, along with explanations of some of the algorithms. Interesting connections of matroids to various branches and areas are also given.
Implementing the DC Mode in Cosmological Simulations with Supercomoving Variables

As emphasized by previous studies, proper treatment of the density fluctuation on the fundamental scale of a cosmological simulation volume-the {sup D}C mode{sup -}is critical for accurate modeling of spatial correlations on scales {approx}> 10% of simulation box size. We provide further illustration of the effects of the DC mode on the abundance of halos in small boxes and show that it is straightforward to incorporate this mode in cosmological codes that use the 'supercomoving' variables. The equations governing evolution of dark matter and baryons recast with these variables are particularly simple and include the expansion factor, and hence the effect of the DC mode, explicitly only in the Poisson equation.
THE CBE HARDWARE ACCELERATOR FOR NUMERICAL RELATIVITY: A SIMPLE APPROACH

Hardware accelerators (such as the Cell Broadband Engine) have recently received a significant amount of attention from the computational science community because they can provide significant gains in the overall performance of many numerical simulations at a low cost. However, such accelerators usually employ a rather unfamiliar and specialized programming model that often requires advanced knowledge of their hardware design. In this article, we demonstrate an alternate and simpler approach toward managing the main complexities in the programming of the cell processor, called software caching. We apply this technique to a numerical relativity (NR) application: a time-domain, finite-difference Kerr black hole perturbation evolver, and present the performance results. We obtain gains in the overall performance of generic simulations that are close to the theoretical maximum that can be obtained through our parallelization approach.
VARIATIONAL PARTICLE SCHEMES FOR THE POROUS MEDIUM EQUATION AND FOR THE SYSTEM OF ISENTROPIC EULER EQUATIONS

We introduce variational particle schemes for the porous medium equation and the system of isentropic Euler equations in one space dimension. The methods are motivated by the interpretation of each of these partial differential equations as a 'steepest descent' on a suitable abstract manifold. We show that our methods capture very well the nonlinear features of the flows.
Simons Observatory Microwave SQUID Multiplexing Readout: Cryogenic RF Amplifier and Coaxial Chain Design

The Simons Observatory (SO) is an upcoming polarization-sensitive cosmic microwave background experiment on the Cerro Toco Plateau (Chile) with large overlap with other optical and infrared surveys (e.g., DESI, LSST, HSC). To enable the readout of $${\mathcal {O}}$$(10,000) detectors in each of the four telescopes of SO, we will employ the microwave SQUID multiplexing technology. With a targeted multiplexing factor of $${\mathcal {O}}$$(1000), microwave SQUID multiplexing has never been deployed on the scale needed for SO. Here we present the design of the cryogenic coaxial cable and RF component chain that connects room temperature readout electronics to superconducting resonators that are coupled to transition edge sensor bolometers operating at sub-Kelvin temperatures. We describe design considerations including cryogenic RF component selection, system linearity, noise, and thermal power dissipation.
The spinful large charge sector of non-relativistic CFTs: from phonons to vortex crystals

We study operators in Schrodinger invariant field theories (non-relativistic conformal field theories or NRCFTs) with large charge (particle number) and spin. Via the state-operator correspondence for NRCFTs, such operators correspond to states of a superfluid in a harmonic trap with phonons or vortices. Using the effective field theory of the Goldstone mode, we compute the dimensions of operators to leading order in the angular momentum L and charge Q. We find a diverse set of scaling behaviors for NRCFTs in both d = 2 and d = 3 spatial dimensions. These results apply to theories with a superfluid phase, such as unitary fermions or critical anyon systems.
The Shadow of a Spherically Accreting Black Hole

We explore a simple spherical model of optically thin accretion on a Schwarzschild black hole, and study the properties of the image as seen by a distant observer. We show that a dark circular region in the center --- a shadow --- is always present. The outer edge of the shadow is located at the photon ring radius $b_{\rm ph} \equiv \sqrt{27}r_g$, where $r_g=GM/c^2$ is the gravitational radius of the accreting mass $M$. The location of the shadow edge is independent of the inner radius at which the accreting gas stops radiating. The size of the observed shadow is thus a signature of the spacetime geometry and it is hardly influenced by accretion details. We briefly discuss the relevance of these results for the Event Horizon Telescope image of the supermassive black hole in M87.
Vertically Sheared Horizontal Flow-Forming Instability in Stratified Turbulence: Analytical Linear Stability Analysis of Statistical State Dynamics Equilibria

AbstractVertically banded zonal jets are frequently observed in weakly or nonrotating stratified turbulence, with the quasi-biennial oscillation in the equatorial stratosphere and the ocean’s equat...
How to Produce an Arbitrarily Small Tensor to Scalar Ratio

In this paper, construct a toy a model which demonstrates that large field single scalar inflation can produce an arbitrarily small scalar to tensor ratio in the window of e-foldings recoverable fr...
Sizing Up the Milky Way: A Bayesian Mixture Model Meta-analysis of Photometric Scale Length Measurements

The exponential scale length ($L_d$) of the Milky Way's (MW's) disk is a critical parameter for describing the global physical size of our Galaxy, important both for interpreting other Galactic measurements and helping us to understand how our Galaxy fits into extragalactic contexts. Unfortunately, current estimates span a wide range of values and often are statistically incompatible with one another. Here, we perform a Bayesian meta-analysis to determine an improved, aggregate estimate for $L_d$, utilizing a mixture-model approach to account for the possibility that any one measurement has not properly accounted for all statistical or systematic errors. Within this machinery we explore a variety of ways of modeling the nature of problematic measurements, and then employ a Bayesian model averaging technique to derive net posterior distributions that incorporate any model-selection uncertainty. Our meta-analysis combines 29 different (15 visible and 14 infrared) photometric measurements of $L_d$ available in the literature; these involve a broad assortment of observational datasets, MW models and assumptions, and methodologies, all tabulated herein. Analyzing the visible and infrared measurements separately yields estimates for $L_d$ of $2.71^{+0.22}_{-0.20}$ kpc and $2.51^{+0.15}_{-0.13}$ kpc, respectively, whereas considering them all combined yields $2.64\pm0.13$ kpc. The ratio between the visible and infrared scale lengths determined here is very similar to that measured in external spiral galaxies. We use these results to update the model of the Galactic disk from our previous work, constraining its stellar mass to be $4.8^{+1.5}_{-1.1}\times10^{10}$ $\textrm{M}_\odot$, and the MW's total stellar mass to be $5.7^{+1.5}_{-1.1}\times10^{10}$ $\textrm{M}_\odot$.
Compression and Conditional Emulation of Climate Model Output

ABSTRACTNumerical climate model simulations run at high spatial and temporal resolutions generate massive quantities of data. As our computing capabilities continue to increase, storing all of the data is not sustainable, and thus it is important to develop methods for representing the full datasets by smaller compressed versions. We propose a statistical compression and decompression algorithm based on storing a set of summary statistics as well as a statistical model describing the conditional distribution of the full dataset given the summary statistics. We decompress the data by computing conditional expectations and conditional simulations from the model given the summary statistics. Conditional expectations represent our best estimate of the original data but are subject to oversmoothing in space and time. Conditional simulations introduce realistic small-scale noise so that the decompressed fields are neither too smooth nor too rough compared with the original data. Considerable attention is paid t...
On the Potts Model Partition Function in an External Field

We study the partition function of the Potts model in an external (magnetic) field, and its connections with the zero-field Potts model partition function. Using a deletion-contraction formulation for the partition function Z for this model, we show that it can be expanded in terms of the zero-field partition function. We also show that Z can be written as a sum over the spanning trees, and the spanning forests, of a graph G. Our results extend to Z the well-known spanning tree expansion for the zero-field partition function that arises though its connections with the Tutte polynomial.
Dynamics of SU(N) supersymmetric gauge theory

Abstract We study the physics of the Seiberg-Witten and Argyres-Faraggi-Klemm-Lerche-Theisen-Yankielowicz solutions of D = 4, N = 2 and N = 1 SU(N) supersymmetric gauge theory. The N = 1 theory is confining and its effective Lagrangian is a spontaneously broken U(1)N−1 abelian gauge theory. We identify some features of its physics which see this internal structure, including a spectrum of different string tensions. We discuss the limit N → ∞, identify a scaling regime in which instanton and monopole effects survive, and give exact results for the crossover from weak to strong coupling along a scaling trajectory. We find a large hierarchy of mass scales in the scaling regime, including very light W bosons, and the absence of weak coupling. The light W's leave a novel imprint on the effective dual magnetic theory. The effective Lagrangian appears to be inadequate to understand the conventional large N limit of the confining N = 1 theory
Metacommutation of Hurwitz primes

Conway and Smith introduced the operation of metacommutation for pairs of primes in the ring of Hurwitz integers in the quaternions. We study the permutation induced on the primes of norm p by a prime of norm q under metacommutation, where p and q are distinct rational primes. In particular, we show that the sign of this permutation is the quadratic character of q modulo p.
The First CO Map of a Low Surface Brightness Galaxy

Using the Owens Valley Radio Observatory (OVRO) Millimeter-Wavelength Array, we have obtained the first CO map of a low surface brightness (LSB) galaxy. The studied galaxy, UGC 01922, was chosen for these observations because of both its previous CO detection with the IRAM 30 m telescope and its classification as a Malin 1 "cousin;" an LSB galaxy with M ≥ 1010 M☉. The OVRO map detected approximately 65% of the CO (1-0) flux found earlier with the single-dish measurements, giving a detected gas mass equivalent to M = 1.1 × 109 M☉. The integrated gas peak lies at the center of the galaxy and coincides with both the optical and 1.4 GHz continuum emission peaks. The molecular gas extends well beyond the OVRO beam size (~4'' or 3 kpc), covering ~25% of the optical bulge. In all, perhaps the most remarkable aspect of this map is its unexceptional appearance. Given that it took over 10 years to successfully detect molecular gas in any LSB system, it is surprising that the appearance and distribution of UGC 01922's CO is similar to what would be expected for a high surface brightness galaxy in the same morphological class.
A comment on duality in N = 1 supersymmetric non-abelian gauge theories

Abstract Recently N. Seiberg has shown that certain N = 1 supersymmetric Yang-Mills theories have the property that their infrared physics can be equivalently described by two different gauge theories, with the strong coupling region of one corresponding to the weak coupling region of the other. This duality leads to interesting results about the infrared dynamics of these theories. We generalize Seiberg's ideas to a new class of models for which a similar duality allows one to obtain rather detailed dynamical information about the long distance physics.
The planes of satellite galaxies problem, suggested solutions, and open questions

Satellite galaxies of the Milky Way and of the Andromeda galaxy have been found to preferentially align in significantly flattened planes of satellite galaxies, and available velocity measurements are indicative of a preference of satellites in those structures to co-orbit. There is an increasing evidence that such kinematically correlated satellite planes are also present around more distant hosts. Detailed comparisons show that similarly anisotropic phase-space distributions of sub-halos are exceedingly rare in cosmological simulations based on the ΛCDM paradigm. Analogs to the observed systems have frequencies of ≤ 0.5% in such simulations. In contrast to other small-scale problems, the satellite planes issue is not strongly affected by baryonic processes because the distribution of sub-halos on scales of hundreds of kpc is dominated by gravitational effects. This makes the satellite planes one of the most serious small-scale problems for ΛCDM. This review summarizes the observational evidence for plan...
Dynamo Processes Constrained by Solar and Stellar Observations

Our understanding of stellar dynamos has largely been driven by the phenomena we have observed of our own Sun. Yet, as we amass longer-term datasets for an increasing number of stars, it is clear that there is a wide variety of stellar behavior. Here we briefly review observed trends that place key constraints on the fundamental dynamo operation of solar-type stars to fully convective M dwarfs, including: starspot and sunspot patterns, various magnetism-rotation correlations, and mean field flows such as differential rotation and meridional circulation. We also comment on the current insight that simulations of dynamo action and flux emergence lend to our working knowledge of stellar dynamo theory. While the growing landscape of both observations and simulations of stellar magnetic activity work in tandem to decipher dynamo action, there are still many puzzles that we have yet to fully understand.
A Performance Study of a Fast-Rate WLAN Fingerprint Measurement Collection Method

Indoor positioning systems exploiting wireless local area network (WLAN) signal measurements, such as received signal strength (RSS), are gaining popularity due to high accuracy of the results. Sets of RSS and other measurements at designated locations from available WLAN access points are conventionally called fingerprints and typically retrieved from network cards at a 1-Hz rate. Such measurement collection is needed for the offline radio map surveying stage which assigns fingerprints to locations, and for online navigation stage when collected measurements are associated with the radio map for positioning. As WLAN networks are not originally designed for localization, the network cards occasionally miss the fingerprints, measurement fluctuations necessitate statistical signal processing, and the surveying process is very time consuming. This paper describes a fast measurement collection approach that addresses the mentioned problems—higher probability of measurement acquisition, more data for statistical processing, and faster surveying. The approach is further analyzed for practical setting applications.
Quark confinement and the renormalization group

Recent approaches to quark confinement are reviewed, with an emphasis on their connection to renormalization group (RG) methods. Basic concepts related to confinement are introduced: the string ten...
Spin tunnelling in mesoscopic systems

We study spin tunnelling in molecular magnets as an instance of a mesoscopic phenomenon, with special emphasis on the molecule Fe8. We show that the tunnel splitting between various pairs of Zeeman levels in this molecule oscillates as a function of applied magnetic field, vanishing completely at special points in the space of magnetic fields, known as diabolical points. This phenomena is explained in terms of two approaches, one based on spin-coherent-state path integrals, and the other on a generalization of the phase integral (or WKB) method to difference equations. Explicit formulas for the diabolical points are obtained for a model Hamiltonian.
Schema Matching using Machine Learning

Databases are the core part of any product, with new companies getting merged and creating cross-functional teams, database merging has become one of the crucial tasks to maintain the efficiency of the product. In the process of database merging, generally, Schemas get redesigned, and Schema Matching is the first step for it. Schema Matching is a method of finding attributes in database fields that are either similar to each other linguistically or represent the same information. Indeed various approaches exist to do automated schema matching, but they fail in different scenarios, such as different language-based fields. In this paper, We explored existing methods (centroid, self-organizing maps, etc.) and proposed a hybrid approach framework that uses both provided data and the schema name to solve a one-to-one schema matching problem. We also introduced the creation of a global dictionary method for one-to-many matching. In global dictionary method, we maps similar fields to same groups using feature extraction and clustering. We have performed experiments using both techniques and compared them to existing approaches. We were able to attain an F1 Score of 0.71 using our hybrid approach, an increase from 0.69 using the existing centroid approach.
SPRING: A Sparsity-Aware Reduced-Precision Monolithic 3D CNN Accelerator Architecture for Training and Inference

CNNs outperform traditional machine learning algorithms across a wide range of applications. However, their ever-growing computational complexity makes it necessary to design efficient hardware accelerators. The potential performance improvement from sparsity has not been adequately addressed. The computation and memory footprint of CNNs can be significantly reduced if sparsity is exploited in network evaluations. It has been shown that activations and weights also have high sparsity levels during the network training phase. Hence, sparsity-aware computation should also be considered in the training phase. To further improve performance and energy efficiency, some accelerators evaluate CNNs with limited precision. However, this is limited to the inference phase since reduced precision sacrifices network accuracy if used in training. In addition, CNN evaluation is usually memory-intensive, especially during training. In this article, we propose SPRING, a SParsity-aware Reduced-precision Monolithic 3D CNN accelerator for trainING and inference. It uses a binary mask scheme to encode sparsities. It uses the stochastic rounding algorithm to train CNNs with reduced precision without accuracy loss. To alleviate the memory bottleneck in CNN evaluation, especially during training, SPRING uses an efficient monolithic 3D nonvolatile memory interface to increase memory bandwidth.
Steady-state distributions of ideal active Brownian particles under confinement and forcing

We develop a formally exact technique for obtaining steady-state distributions of non-interacting active Brownian particles in a variety of systems. Our technique draws on results from the theory of two-way diffusion equations to solve the steady-state Smoluchowski equation for the 1-particle distribution function. The methods are employed to study in detail three scenarios: 1) confinement in a channel, 2) a constant flux steady state, and 3) sedimentation in a uniform external field. In each scenario, known behaviors are reproduced and precisely quantified, and new results are presented. In particular, in the constant flux state we derive an effective diffusivity which interpolates between the ballistic behavior of particle trajectories at short distances and their diffusive behavior at large distances. We also calculate the sedimentation profile of active Brownian particles near a wall, which complements earlier studies on the part far from the wall. Our techniques easily generalize to other active models, including systems whose activity is modeled in terms of Gaussian colored noise.
Interacting Induced Dark Energy Model

Following the idea of the induced matter theory, for a non–vacuum five–dimensional version of general relativity, we propose a model in which the induced terms emerging from the extra dimension in our four–dimensional space–time, supposed to be as dark energy. Then we investigate the FLRW type cosmological equations and illustrate that when the scale factor of the fifth dimension has no dynamics, in early time the universe expands with deceleration and then in late time, expands with acceleration. In this case, the state parameter of the effective dark energy has a range of $-1<\bar {w}_{X}<0$ and it has the value − 1/2 for present time. The results for current acceleration impose that ΩX∘ > 2ΩM∘ which is in agreement with the measurements. We show that the effective energy density of dark energy have been having the same order of magnitude of the effective energy density of matter from the early time in the decelerating epoch of the universe expansion until now. The model avoids the cosmological coincidence problem.
A geometric transition from hyperbolic to anti-de Sitter geometry

We introduce a geometric transition between two homogeneous three-dimensional geometries: hyperbolic geometry and anti-de Sitter (AdS) geometry. Given a path of three-dimensional hyperbolic structures that collapse down onto a hyperbolic plane, we describe a method for constructing a natural continuation of this path into AdS structures. In particular, when hyperbolic cone manifolds collapse, the AdS manifolds generated on the “other side” of the transition have tachyon singularities. The method involves the study of a new transitional geometry called half-pipe geometry. We demonstrate these methods in the case when the manifold is the unit tangent bundle of the .2;m;m/ triangle orbifold for m 5.
Bootstrapping the minimal 3D SCFT

We study the conformal bootstrap constraints for 3D conformal field theories with a ℤ2 or parity symmetry, assuming a single relevant scalar operator ϵ that is invariant under the symmetry. When there is additionally a single relevant odd scalar σ, we map out the allowed space of dimensions and three-point couplings of such “Ising-like” CFTs. If we allow a second relevant odd scalar σ′, we identify a feature in the allowed space compatible with 3D $$ \mathcal{N} $$ = 1 superconformal symmetry and conjecture that it corresponds to the minimal $$ \mathcal{N} $$ = 1 supersymmetric extension of the Ising CFT. This model has appeared in previous numerical bootstrap studies, as well as in proposals for emergent supersymmetry on the boundaries of topological phases of matter. Adding further constraints from 3D $$ \mathcal{N} $$ =1 superconformal symmetry, we isolate this theory and use the numerical bootstrap to compute the leading scaling dimensions Δσ = Δϵ − 1 = .58444(22) and three-point couplings λσσϵ = 1.0721(2) and λϵϵϵ = 1.67(1). We additionally place bounds on the central charge and use the extremal functional method to estimate the dimensions of the next several operators in the spectrum. Based on our results we observe the possible exact relation λϵϵϵ/λσσϵ = tan(1).
Accelerating exact and approximate inference for (distributed) discrete optimization with GPUs

Discrete optimization is a central problem in artificial intelligence. The optimization of the aggregated cost of a network of cost functions arises in a variety of problems including Weighted Constraint Programs (WCSPs), Distributed Constraint Optimization (DCOP), as well as optimization in stochastic variants such as the tasks of finding the most probable explanation (MPE) in belief networks. Inference-based algorithms are powerful techniques for solving discrete optimization problems, which can be used independently or in combination with other techniques. However, their applicability is often limited by their compute intensive nature and their space requirements. This paper proposes the design and implementation of a novel inference-based technique, which exploits modern massively parallel architectures, such as those found in Graphical Processing Units (GPUs), to speed up the resolution of exact and approximated inference-based algorithms for discrete optimization. The paper studies the proposed algorithm in both centralized and distributed optimization contexts. The paper demonstrates that the use of GPUs provides significant advantages in terms of runtime and scalability, achieving up to two orders of magnitude in speedups and showing a considerable reduction in execution time (up to 345 times faster) with respect to a sequential version.
New Rotation Period Measurements for M Dwarfs in the Southern Hemisphere: An Abundance of Slowly Rotating, Fully Convective Stars

Stellar rotation periods are valuable both for constraining models of angular momentum loss and for under- standing how magnetic features impact inferences of exoplanet parameters. Building on our previous work in the northern hemisphere, we have used long-term, ground-based photometric monitoring from the MEarth Observatory to measure 234 rotation periods for nearby, southern hemisphere M dwarfs. Notable examples include the exoplanet hosts GJ 1132, LHS 1140, and Proxima Centauri. We find excellent agreement between our data and K2 photometry for the overlapping subset. Amongst the sample of stars with the highest quality datasets, we recover periods in 66%; as the length of the dataset increases, our recovery rate approaches 100%. The longest rotation periods we detect are around 140 days, which we suggest represent the periods that are reached when M dwarfs are as old as the local thick disk (about 9 Gyr).
Ehrenfest+R dynamics. I. A mixed quantum-classical electrodynamics simulation of spontaneous emission.

The dynamics of an electronic system interacting with an electromagnetic field is investigated within mixed quantum–classical theory. Beyond the classical path approximation (where we ignore all feedback from the electronic system on the photon field), we consider all electron–photon interactions explicitly according to Ehrenfest (i.e., mean-field) dynamics and a set of coupled Maxwell–Liouville equations. Because Ehrenfest dynamics cannot capture certain quantum features of the photon field correctly, we propose a new Ehrenfest+R method that can recover (by construction) spontaneous emission while also distinguishing between electromagnetic fluctuations and coherent emission.
Kinematic Evidence for Halo Substructure in Spiral Galaxies

We present the results of a kinematic study of planetary nebulae in the extreme outskirts of two spiral galaxies, M83 (NGC 5236) and M94 (NGC 4736). We find that in the inner regions of the galaxies, the vertical velocity dispersion (? z ) falls off exponentially with the light, as expected for a constant mass-to-light ratio, constant thickness disk. However, starting at four optical scale lengths, ? z asymptotes out at roughly 20 km s?1. Our analysis finds evidence for significant flaring in the outer regions as well, especially in M94. These observations are in excellent agreement with predictions derived from models of disk heating by halo substructure, and demonstrate how kinematic surveys in the outer disks of spirals can be used to test hierarchical models of galaxy formation.
Constraining Primordial Non-Gaussianities from the WMAP2 2-1 Cumulant Correlator Power Spectrum

We measure the 2-1 cumulant correlator power spectrum C, a degenerate bispectrum, from the second data release of the Wilkinson Microwave Anisotropy Probe (WMAP). Our high-resolution measurements with SpICE span a large configuration space (168 × 999) corresponding to the possible cross-correlations of the maps recorded by the different differencing assemblies. We present a novel method to recover the eigenmodes of the correspondingly large Monte Carlo covariance matrix. We examine its eigenvalue spectrum and use random matrix theory to show that the off-diagonal terms are dominated by noise. We minimize the χ2 to obtain constraints for the nonlinear coupling parameter fNL = 22 ± 52 (1 σ).
Towards Optimal Gradient Bounds for the Torsion Function in the Plane

Let $$\Omega \subset \mathbb {R}^2$$ be a bounded, convex domain and let u be the solution of $$-\Delta u = 1$$ vanishing on the boundary $$\partial \Omega $$ . The estimate $$\begin{aligned} \Vert \nabla u\Vert _{L^{\infty }(\Omega )} \le c |\Omega |^{1/2} \end{aligned}$$ is classical. We use the P-functional, the stability theory of the torsion function and Brownian motion to establish the estimate for a universal $$c < (2\pi )^{-1/2}$$ . We also give a numerical construction showing that the optimal constant satisfies $$c \ge 0.358$$ . The problem is important in different settings: (1) as the maximum shear stress in Saint Venant Elasticity Theory, (2) as an optimal control problem for the constrained maximization of the lifetime of Brownian motion started close to the boundary, and (3) optimal Hermite–Hadamard inequalities for subharmonic functions on convex domains.
Basis set convergence of Wilson basis functions for electronic structure

There are many ways to numerically represent chemical systems in order to compute their electronic structure. Basis functions may be localized in real-space (atomic orbitals), in momentum-space (plane waves), or in both components of phase-space. Such phase-space localized basis functions in the form of wavelets have been used for many years in the electronic structure. In this paper, we turn to a phase-space localized basis set first introduced by Wilson [Generalized Wannier Functions (Cornell University, 1987), preprint]. We provide the first full study of this basis and its numerical implementation. To calculate electronic energies of a variety of small molecules and states, we utilize the sum-of-products form, Gaussian quadratures, and introduce methods for selecting sample points from a grid of phase-space localized Wilson basis. Both full configuration interaction and Hartree-Fock implementations are discussed and implemented numerically. As with many grid based methods, describing both tightly bound and diffuse orbitals is challenging so we have considered augmenting the Wilson basis set as projected Slater-type orbitals. We have also compared the Wilson basis set against the recently introduced wavelet transformed Gaussians (gausslets). Throughout, we give comments on the implementation and use small atoms and molecules to illustrate the convergence properties of the Wilson basis.
Learning Multi-Dimensional Indexes

Scanning and filtering over multi-dimensional tables are key operations in modern analytical database engines. To optimize the performance of these operations, databases often create clustered indexes over a single dimension or multi-dimensional indexes such as R-Trees, or use complex sort orders (e.g., Z-ordering). However, these schemes are often hard to tune and their performance is inconsistent across different datasets and queries. In this paper, we introduce Flood, a multi-dimensional in-memory read-optimized index that automatically adapts itself to a particular dataset and workload by jointly optimizing the index structure and data storage layout. Flood achieves up to three orders of magnitude faster performance for range scans with predicates than state-of-the-art multi-dimensional indexes or sort orders on real-world datasets and workloads. Our work serves as a building block towards an end-to-end learned database system.
A Catalog of Ultra-compact High Velocity Clouds from the ALFALFA Survey: Local Group Galaxy Candidates?

We present a catalog of 59 ultra-compact high velocity clouds (UCHVCs) extracted from the 40% complete ALFALFA HI-line survey. The ALFALFA UCHVCs have median flux densities of 1.34 Jy km s–1, median angular diameters of 10', and median velocity widths of 23 km s–1. We show that the full UCHVC population cannot easily be associated with known populations of high velocity clouds. Of the 59 clouds presented here, only 11 are also present in the compact cloud catalog extracted from the commensal GALFA-HI survey, demonstrating the utility of this separate dataset and analysis. Based on their sky distribution and observed properties, we infer that the ALFALFA UCHVCs are consistent with the hypothesis that they may be very low mass galaxies within the Local Volume. In that case, most of their baryons would be in the form of gas, and because of their low stellar content, they remain unidentified by extant optical surveys. At distances of ~1 Mpc, the UCHVCs have neutral hydrogen (H I) masses of ~105-106 M ☉, H I diameters of ~2-3 kpc, and indicative dynamical masses within the H I extent of ~107-108 M ☉, similar to the Local Group ultra-faint dwarf Leo T. The recent ALFALFA discovery of the star-forming, metal-poor, low mass galaxy Leo P demonstrates that this hypothesis is true in at least one case. In the case of the individual UCHVCs presented here, confirmation of their extragalactic nature will require further work, such as the identification of an optical counterpart to constrain their distance.