cssi/SciSciGPT-SciSciNet huggingface dataset:
MAGNETOROTATIONAL TURBULENCE TRANSPORTS ANGULAR MOMENTUM IN STRATIFIED DISKS WITH LOW MAGNETIC PRANDTL NUMBER BUT MAGNETIC REYNOLDS NUMBER ABOVE A CRITICAL VALUE

The magnetorotational instability (MRI) may dominate outward transport of angular momentum in accretion disks, allowing material to fall onto the central object. Previous work has established that the MRI can drive a mean-field dynamo, possibly leading to a self-sustaining accretion system. Recently, however, simulations of the scaling of the angular momentum transport parameter αSS with the magnetic Prandtl number Pm have cast doubt on the ability of the MRI to transport astrophysically relevant amounts of angular momentum in real disk systems. Here, we use simulations including explicit physical viscosity and resistivity to show that when vertical stratification is included, mean-field dynamo action operates, driving the system to a configuration in which the magnetic field is not fully helical. This relaxes the constraints on the generated field provided by magnetic helicity conservation, allowing the generation of a mean field on timescales independent of the resistivity. Our models demonstrate the existence of a critical magnetic Reynolds number Rmcrit, below which transport becomes strongly Pm-dependent and chaotic, but above which the transport is steady and Pm-independent. Prior simulations showing Pm dependence had Rm < Rmcrit. We conjecture that this steady regime is possible because the mean-field dynamo is not helicity-limited and thus does not depend on the details of the helicity ejection process. Scaling to realistic astrophysical parameters suggests that disks around both protostars and stellar mass black holes have Rm Rmcrit. Thus, we suggest that the strong Pm dependence seen in recent simulations does not occur in real systems.
DETECTION OF RADIO EMISSION FROM FIREBALLS

We present the findings from the Prototype All-Sky Imager, a back end correlator of the first station of the Long Wavelength Array, which has recorded over 11,000 hr of all-sky images at frequencies between 25 and 75 MHz. In a search of this data for radio transients, we have found 49 long-duration (10 s of seconds) transients. Ten of these transients correlate both spatially and temporally with large meteors (fireballs), and their signatures suggest that fireballs emit a previously undiscovered low frequency, non-thermal pulse. This emission provides a new probe into the physics of meteors and identifies a new form of naturally occurring radio transient foreground.
String unification, higher-level gauge symmetries, and exotic hypercharge normalizations

Abstract We explore the extent to which string theories with higher-level gauge symmetries and nonstandard hypercharge normalizations can reconcile the discrepancy between the string unification scale and the GUT scale extrapolated from the Minimal Supersymmetric Standard Model (MSSM). We determine the phenomenologically allowed regions of (ky, k2, k3) parameter space, and investigate the proposal that there might exist string models with exotic hypercharge normalizations ky which are less than their usual value k y = 5 3 . For a broad class of heterotic string models (encompassing most realistic string models which have been constructed), we prove that k y ⩾ 5 3 . Beyond this class, however, we show that there exist consistent MSSM embeddings which lead to k y 5 3 . We also consider the constraints imposed on by demanding charge integrality of all unconfined string states, and show that only a limited set of hypercolor confining groups and corresponding values of ky are possible.
On the correctness of pull-tabbing

Pull-tabbing is an evaluation approach for functional logic computations, b ased on a graph transformation recently proposed, which avoids making irrevocable non-deterministic choices that would jeopardize the completeness of computations. In contrast to other approaches with this property, it does not require an upfront cloning of a possibly large portion of the choice’s context. We formally define the pull-tab transformation, characterize the class of programs f or which the transformation is intended, extend the computations in these programs to include the transformation, and prove the correctness of the extended computations.
A quantum Hall fluid of vortices

In this note we demonstrate that vortices in a non-relativistic Chern-Simons theory form a quantum Hall fluid. We show that the vortex dynamics is controlled by the matrix mechanics previously proposed by Polychronakos as a description of the quantum Hall droplet. As the number of vortices becomes large, they fill the plane and a hydrodynamic treatment becomes possible, resulting in the non-commutative theory of Susskind. Key to the story is the recent D-brane realisation of vortices and their moduli spaces.
Rational analogs of projective planes

In this paper, we study the existence of high-dimensional, closed, smooth manifolds whose rational homotopy type resembles that of a projective plane. Applying rational surgery, the problem can be reduced to finding possible Pontryagin numbers satisfying the Hirzebruch signature formula and a set of congruence relations, which turns out to be equivalent to finding solutions to a system of Diophantine equations.
Dynamical Evolution of Galaxies in Clusters

Tidal forces acting on galaxies in clusters lead to a strong dynamical evolution. In order to quantify the amount of evolution, I run self-consistent N-body simulations of disk galaxies for a variety of models in the hierarchically forming clusters. The tidal field along the galactic orbits is extracted from the simulations of cluster formation in the Ω0 = 1, 0.4, and 0.4, ΩΛ = 0.6 cosmological scenarios. For large spiral galaxies with a rotation speed of 250 km s-1, tidal interactions truncate massive dark matter halos at 30 ± 6 kpc and thicken stellar disks by a factor of 2-3, increasing Toomre's parameter to Q 2 and halting star formation. Low-density galaxies, such as the dwarf spheroidals with a circular velocity of 20 km s-1 and the extended low surface brightness galaxies with a scale length of 10-15 kpc, are completely disrupted by tidal shocks. Their debris contribute to the diffuse intracluster light. The tidal effects are significant not only in the core but throughout the cluster and can be parametrized by the critical tidal density. The tidally induced evolution results in the transformation of the infalling spirals into S0 galaxies and in the depletion of the low surface brightness galaxy population. In the low-Ω0 cosmological models, clusters form earlier and produce stronger evolution of galaxies.
The Renormalization Effects in the Microstrip-SQUID Amplifier

The peculiarities of the microstrip-DC SQUID amplifier caused by the resonant structure of the input circuit are analyzed. It is shown that the mutual inductance, that couples the input circuit and the SQUID loop, depends on the frequency of electromagnetic field. The renormalization of the SQUID parameters due to the screening effect of the input circuit vanishes when the Josephson frequency is much greater than the signal frequency.
Design of Atomically Precise Nanoscale Negative Differential Resistance Devices

Down-scaling device dimensions to the nanometer range raises significant challenges to traditional device design, due to potential current leakage across nanoscale dimensions and the need to maintain reproducibility while dealing with atomic-scale components. Here we investigate negative differential resistance (NDR) devices based on atomically precise graphene nanoribbons. Our computational evaluation of the traditional double-barrier resonant tunneling diode NDR structure uncovers important issues at the atomic scale, concerning the need to minimize the tunneling current between the leads while achieving high peak current. We propose a new device structure consisting of multiple short segments that enables high current by the alignment of electronic levels across the segments while enlarging the tunneling distance between the leads. The proposed structure can be built with atomic precision using a scanning tunneling microscope (STM) tip during an intermediate stage in the synthesis of an armchair nanoribbon. An experimental evaluation of the band alignment at the interfaces and an STM image of the fabricated active part of the device are also presented. This combined theoretical-experimental approach opens a new avenue for the design of nanoscale devices with atomic precision.
Load Balancing in Hypergraphs

Consider a simple locally finite hypergraph on a countable vertex set, where each edge represents one unit of load which should be distributed among the vertices defining the edge. An allocation of load is called balanced if load cannot be moved from a vertex to another that is carrying less load. We analyze the properties of balanced allocations of load. We extend the concept of balancedness from finite hypergraphs to their local weak limits in the sense of Benjamini and Schramm (Electron J Probab 6(23):13, 2001) and Aldous and Steele (in: Probability on discrete structures. Springer, Berlin, pp 1–72, 2004). To do this, we define a notion of unimodularity for hypergraphs which could be considered an extension of unimodularity in graphs. We give a variational formula for the balanced load distribution and, in particular, we characterize it in the special case of unimodular hypergraph Galton–Watson processes. Moreover, we prove the convergence of the maximum load under some conditions. Our work is an extension to hypergraphs of Anantharam and Salez (Ann Appl Probab 26(1):305–327, 2016), which considered load balancing in graphs, and is aimed at more comprehensively resolving conjectures of Hajek (IEEE Trans Inf Theory 36(6):1398–1414, 1990).
Compact tetraquark interpretation of the XYZ states

The past decade has witnessed the observation of several exotic charmonium-like resonances, some of which are manifestly non-qq¯ mesons. We review one of the most popular interpretations of such states: the compact tetraquark in the constituent diquark-antidiquark picture. Moreover, we discuss some unexplored decay channels, which are particularly sensitive to the different phenomenological models, and could therefore shed some light on the nature of these fascinating states. Some brief comments on the recently observed pentaquarks are also included.
Three upsilon transforms related to tempered stable distributions

We discuss the properties of three upsilon transforms, which are related to the class of $p$-tempered $\alpha$-stable ($TS^p_\alpha$) distributions. In particular, we characterize their domains and show how they can be represented as compositions of each other. Further, we show that if $-\infty<\beta<\alpha<2$ and $0<q<p<\infty$ then they can be used to transform the L\'evy measures of $TS^p_\beta$ distributions into those of $TS^q_\alpha$.
Assessing the Privacy Benefits of Domain Name Encryption

As Internet users have become more savvy about the potential for their Internet communication to be observed, the use of network traffic encryption technologies (e.g., HTTPS/TLS) is on the rise. However, even when encryption is enabled, users leak information about the domains they visit via DNS queries and via the Server Name Indication (SNI) extension of TLS. Two recent proposals to ameliorate this issue are DNS over HTTPS/TLS (DoH/DoT) and Encrypted SNI (ESNI). In this paper we aim to assess the privacy benefits of these proposals by considering the relationship between hostnames and IP addresses, the latter of which are still exposed. We perform DNS queries from nine vantage points around the globe to characterize this relationship. We quantify the privacy gain offered by ESNI for different hosting and CDN providers using two different metrics, the k -anonymity degree due to co-hosting and the dynamics of IP address changes. We find that 20% of the domains studied will not gain any privacy benefit since they have a one-to-one mapping between their hostname and IP address. On the other hand, 30% will gain a significant privacy benefit with a k value greater than 100, since these domains are co-hosted with more than 100 other domains. Domains whose visitors' privacy will meaningfully improve are far less popular, while for popular domains the benefit is not significant. Analyzing the dynamics of IP addresses of long-lived domains, we find that only 7.7% of them change their hosting IP addresses on a daily basis. We conclude by discussing potential approaches for website owners and hosting/CDN providers for maximizing the privacy benefits of ESNI.
Magnetic Dynamo Action in Helical Turbulence

We investigate magnetic field amplification in a turbulent velocity field with nonzero helicity, in the framework of the kinematic Kazantsev-Kraichnan model. We present the numerical solution of the model for the practically important case of Kolmogorov distribution of velocity fluctuations, with a large magnetic Reynolds number. We find that in contrast to the nonhelical case where growing magnetic fields are described by a few bound eigenmodes concentrated inside the inertial interval of the velocity field, in the helical case the number of bound eigenmodes considerably increases; moreover, new unbound eigenmodes appear. Both bound and unbound eigenmodes contribute to the large-scale magnetic field. This indicates a limited applicability of the conventional alpha model of a large-scale dynamo action, which captures only unbound modes.
Halo independent comparison of direct dark matter detection data

We extend the halo-independent method of Fox, Liu, and Weiner to include energy resolution and efficiency with arbitrary energy dependence, making it more suitable for experiments to use in presenting their results. Then we compare measurements and upper limits on the direct detection of low mass ( ~ 10 GeV) weakly interacting massive particles with spin-independent interactions, including the upper limit on the annual modulation amplitude from the CDMS collaboration. We find that isospin-symmetric couplings are severely constrained both by XENON100 and CDMS bounds, and that isospin-violating couplings are still possible at the lowest energies, while the tension of the higher energy CoGeNT bins with the CDMS modulation constraint remains. We find the CRESST-II signal is not compatible with the modulation signals of DAMA and CoGeNT.
CALIBRATING UV STAR FORMATION RATES FOR DWARF GALAXIES FROM STARBIRDS

Integrating our knowledge of star formation (SF) traced by observations at different wavelengths is essential for correctly interpreting and comparing SF activity in a variety of systems and environments. This study compares extinction corrected integrated ultraviolet (UV) emission from resolved galaxies with color?magnitude diagram (CMD) based star formation rates (SFRs) derived from resolved stellar populations and CMD fitting techniques in 19 nearby starburst and post-starburst dwarf galaxies. The data sets are from the panchromatic Starburst Irregular Dwarf Survey and include deep legacy GALEX UV imaging, Hubble Space Telescope optical imaging, and Spitzer MIPS imaging. For the majority of the sample, the integrated near-UV fluxes predicted from the CMD-based SFRs?using four different models?agree with the measured, extinction corrected, integrated near-UV fluxes from GALEX images, but the far-UV (FUV) predicted fluxes do not. Furthermore, we find a systematic deviation between the SFRs based on integrated FUV luminosities and existing scaling relations, and the SFRs based on the resolved stellar populations. This offset is not driven by different SF timescales, variations in SFRs, UV attenuation, nor stochastic effects. This first comparison between CMD-based SFRs and an integrated FUV emission SFR indicator suggests that the most likely cause of the discrepancy is the theoretical FUV?SFR calibration from stellar evolutionary libraries and/or stellar atmospheric models. We present an empirical calibration of the FUV-based SFR relation for dwarf galaxies, with uncertainties, which is ?53% larger than previous relations.
More pendants for Polya: two loops in the SU(2) sector

We extend the methods of Spradlin and Volovich to compute the partition function for a conformally-invariant gauge theory on × S3 in which the dilatation operator is represented by a spin-chain hamiltonian acting on pairs of states, not necessarily nearest neighbors. A specific application of this is the two-loop dilatation operator of the planar SU(2) subsector of the = 4 SU(N) super Yang-Mills theory in the large-N limit. We compute the partition function and Hagedorn temperature for this sector to second order in the gauge coupling. The Hagedorn temperature is to be interpreted as giving the exponentially-rising portion of the density of states of the SU(2) sector, which may be a signal of stringy behavior in the dual theory.
Radio Spectroscopic Imaging of a Solar Flare Termination Shock: Split-band Feature as Evidence for Shock Compression

Solar flare termination shocks have been suggested as one of the promising drivers for particle acceleration in solar flares, yet observational evidence remains rare. By utilizing radio dynamic spectroscopic imaging of decimetric stochastic spike bursts in an eruptive flare, Chen et al. found that the bursts form a dynamic surface-like feature located at the ending points of fast plasma downflows above the looptop, interpreted as a flare termination shock. One piece of observational evidence that strongly supports the termination shock interpretation is the occasional split of the emission band into two finer lanes in frequency, similar to the split-band feature seen in fast-coronal-shock-driven type II radio bursts. Here we perform spatially, spectrally, and temporally resolved analysis of the split-band feature of the flare termination shock event. We find that the ensemble of the radio centroids from the two split-band lanes each outlines a nearly co-spatial surface. The high-frequency lane is located slightly below its low frequency counterpart by ~0.8 Mm, which strongly supports the shock upstream-downstream interpretation. Under this scenario, the density compression ratio across the shock front can be inferred from the frequency split, which implies a shock with a Mach number of up to 2.0. Further, the spatiotemporal evolution of the density compression along the shock front agrees favorably with results from magnetohydrodynamics simulations. We conclude that the detailed variations of the shock compression ratio may be due to the impact of dynamic plasma structures in the reconnection outflows, which results in distortion of the shock front.
Rare slips in fluctuating synchronized oscillator networks.

We study rare phase slips due to noise in synchronized Kuramoto oscillator networks. In the small-noise limit, we demonstrate that slips occur via large fluctuations to saddle phase-locked states. For tree topologies, slips appear between subgraphs that become disconnected at a saddle-node bifurcation, where phase-locked states lose stability generically. This pattern is demonstrated for sparse networks with several examples. Scaling laws are derived and compared for different tree topologies. On the other hand, for dense networks slips occur between oscillators on the edges of the frequency distribution. If the distribution is discrete, the probability-exponent for large fluctuations to occur scales linearly with the system size. However, if the distribution is continuous, the probability is a constant in the large network limit, as individual oscillators fluctuate to saddles while all others remain fixed. In the latter case, the network’s coherence is approximately preserved.We study rare phase slips due to noise in synchronized Kuramoto oscillator networks. In the small-noise limit, we demonstrate that slips occur via large fluctuations to saddle phase-locked states. For tree topologies, slips appear between subgraphs that become disconnected at a saddle-node bifurcation, where phase-locked states lose stability generically. This pattern is demonstrated for sparse networks with several examples. Scaling laws are derived and compared for different tree topologies. On the other hand, for dense networks slips occur between oscillators on the edges of the frequency distribution. If the distribution is discrete, the probability-exponent for large fluctuations to occur scales linearly with the system size. However, if the distribution is continuous, the probability is a constant in the large network limit, as individual oscillators fluctuate to saddles while all others remain fixed. In the latter case, the network’s coherence is approximately preserved.
New signatures and limits on R -parity violation from resonant squark production

We discuss resonant squark production at the LHC via baryonic R-parity violating interactions. The cross section easily exceeds pair-production and a new set of signatures can be used to probe squarks, particularly stops. These include dijet resonances, same-sign top quarks and four-jet resonances with large b-jet multiplicities, as well as the possibility of displaced neutralino decays. We use publicly available searches at $$ \sqrt{s}=8 $$ TeV and first results from collisions at $$ \sqrt{s}=13 $$ TeV to set upper limits on R-parity violating couplings, with particular focus on simplified models with light stops and neutralinos. The exclusion reach of these signatures is comparable to R-parity-conserving searches, $$ {m}_{\tilde{t}} $$ ≃ 500–700 GeV. In addition, we find that O(1) couplings involving the stop can be excluded well into the multi-TeV range, and stress that searches for single- and pair-produced four-jet resonances will be necessary to exclude sub-TeV stops for a natural SUSY spectrum with light higgsinos.
Instance Based Approximations to Profile Maximum Likelihood

In this paper we provide a new efficient algorithm for approximately computing the profile maximum likelihood (PML) distribution, a prominent quantity in symmetric property estimation. We provide an algorithm which matches the previous best known efficient algorithms for computing approximate PML distributions and improves when the number of distinct observed frequencies in the given instance is small. We achieve this result by exploiting new sparsity structure in approximate PML distributions and providing a new matrix rounding algorithm, of independent interest. Leveraging this result, we obtain the first provable computationally efficient implementation of PseudoPML, a general framework for estimating a broad class of symmetric properties. Additionally, we obtain efficient PML-based estimators for distributions with small profile entropy, a natural instance-based complexity measure. Further, we provide a simpler and more practical PseudoPML implementation that matches the best-known theoretical guarantees of such an estimator and evaluate this method empirically.
Strong and Weak Optimizations in Classical and Quantum Models of Stochastic Processes

Among the predictive hidden Markov models that describe a given stochastic process, the $$\epsilon \text{-machine }$$ is strongly minimal in that it minimizes every Renyi-based memory measure. Quantum models can be smaller still. In contrast with the $$\epsilon \text{-machine }$$ ’s unique role in the classical setting, however, among the class of processes described by pure-state hidden quantum Markov models, there are those for which there does not exist any strongly minimal model. Quantum memory optimization then depends on which memory measure best matches a given problem’s circumstance.
Globular cluster abundances and what they can tell us about galaxy formation

We review the properties of globular clusters (GCs) which make them useful for studying the Galactic halo, Galactic chemical evolution and the early stages of the formation of the Milky Way. We review the evidence that GCs have a chemical inventory similar to those of halo field stars. We discuss the abundance ratios for dSph galaxies and show that it is possible to have formed at least part of the Galactic-halo field stellar population by dissolving GCs and/or accreting dSph galaxies, but only if this occurred at an early stage in the formation of the Galaxy. We review the constraints on halo-formation timescales deduced from the low magnesium isotopic ratios in metal-poor halo field dwarfs, which indicate that asymptotic giant-branch (AGB) stars did not have time to contribute significantly, while M71 contains two populations, one without and also one with a substantial AGB contribution. We review the limited evidence for GCs with a second population showing additional contributions from Type II supernovae, currently confined to ω Cen, M54 and M22, all of which may have been the nuclei or central regions of accreted galaxies. We check our own data for additional similar GCs and find preliminary indications that NGC 2419, a massive GC far in the outer Galactic halo, may also belong to this group.
Gravitino production suppressed by dynamics of sgoldstino

In supersymmetric theories, the gravitino is abundantly produced in the early Universe from thermal scattering, resulting in a strong upper bound on the reheat temperature after inflation. We point out that the gravitino problem may be absent or very mild due to the early dynamics of a supersymmetry breaking field, i.e. a sgoldstino. In models of low scale mediation, the field value of the sgoldstino determines the mediation scale and is in general different in the early Universe from the present one. A large initial field value since the era of the inflationary reheating suppresses the gravitino production significantly. We investigate in detail the cosmological evolution of the sgoldstino and show that the reheat temperature may be much higher than the conventional upper bound, restoring the compatibility with thermal leptogenesis.
Isospin asymmetry in nuclei, neutron stars and heavy-ion collisions

The roles of isospin asymmetry in nuclei and neutron stars are investigated using a range of potential and field-theoretical models of nucleonic matter. The parameters of these models are fixed by fitting the properties of homogeneous bulk matter and closed-shell nuclei. We discuss and unravel the causes of correlations among the neutron skin thickness in heavy nuclei, the pressure of beta-equilibrated matter at a density of 0.1 fm−3, and the radii of moderate mass neutron stars. The influence of symmetry energy on observables in heavy-ion collisions is summarized.
Soft phase lags of pulsed emission from the millisecond x-ray pulsar sax j1808.4-3658

We report the discovery of phase shifts between X-ray pulses at different energies in the newly discovered millisecond X-ray pulsar SAX J1808.4-3658. The results show that low-energy pulses lag high-energy pulses by as much as ~0.2 ms (or ~8% of the pulse period). The measurements were made in two different ways: (1) computing cross-power spectra between different energy bands, and (2) cross-correlating the folded pulse profiles in different energy bands; consistent results were obtained. We speculate that the observed soft lags might be related to the lateral expansion and subsequent cooling of a "hot spot" on the neutron star surface in which the pulsed X-ray emission originates. Also presented is the possibility of producing soft lags via Compton downscattering of hard X-ray photons from the hot spot in the cool surrounding atmosphere. We will discuss possible X-ray production mechanisms for SAX J1808.4-3658 and constraints on the emission environment, based on the observed soft lags, pulse profiles, and energy spectrum.
Four-dimensional gravity as an almost-Poisson system

In this paper, we examine the phase space structure of a noncanonical formulation of four-dimensional gravity referred to as the Instanton representation of Plebanski gravity (IRPG). The typical Hamiltonian (symplectic) approach leads to an obstruction to the definition of a symplectic structure on the full phase space of the IRPG. We circumvent this obstruction, using the Lagrange equations of motion, to find the appropriate generalization of the Poisson bracket. It is shown that the IRPG does not support a Poisson bracket except on the vector constraint surface. Yet there exists a fundamental bilinear operation on its phase space which produces the correct equations of motion and induces the correct transformation properties of the basic fields. This bilinear operation is known as the almost-Poisson bracket, which fails to satisfy the Jacobi identity and in this case also the condition of antisymmetry. We place these results into the overall context of nonsymplectic systems.
Local adaption for approximation and minimization of univariate functions

Abstract Most commonly used adaptive algorithms for univariate real-valued function approximation and global minimization lack theoretical guarantees. Our new locally adaptive algorithms are guaranteed to provide answers that satisfy a user-specified absolute error tolerance for a cone, C , of non-spiky input functions in the Sobolev space W 2 , ∞ [ a , b ] . Our algorithms automatically determine where to sample the function—sampling more densely where the second derivative is larger. The computational cost of our algorithm for approximating a univariate function f on a bounded interval with L ∞ -error no greater than e is O ( ‖ f ″ ‖ 1 2 / e ) as e → 0 . This is the same order as that of the best function approximation algorithm for functions in C . The computational cost of our global minimization algorithm is of the same order and the cost can be substantially less if f significantly exceeds its minimum over much of the domain. Our Guaranteed Automatic Integration Library (GAIL) contains these new algorithms. We provide numerical experiments to illustrate their superior performance.
Quantum Integrability in Systems with Finite Number of Levels

We consider the problem of defining quantum integrability in systems with finite number of energy levels starting from commuting matrices and construct new general classes of such matrix models with a given number of commuting partners. We argue that if the matrices depend on a (real) parameter, one can define quantum integrability from this feature alone, leading to specific results such as exact solvability, Poissonian energy level statistics and to level crossings.
THE FREQUENCY OF TIDAL FEATURES ASSOCIATED WITH NEARBY LUMINOUS ELLIPTICAL GALAXIES FROM A STATISTICALLY COMPLETE SAMPLE

We present a deep broadband optical imaging study of a complete sample of luminous elliptical galaxies (MB < –20) at distances 15-50 Mpc, selected from the Tully catalog of nearby galaxies. The images are flat to ~0.35% across the 20' field and reach a V-band depth of 27.7 mag arcsec–2. We derive an objective tidal interaction parameter for all galaxies and find that 73% of them show tidal disturbance signatures in their stellar bodies. This is the first time that such an analysis is done on a statistically complete sample and it confirms that tidal features in ellipticals are common even in the local universe. From the dynamical time of the sample galaxies at the innermost radius where tidal features are detected, we estimate the mass assembly rate of nearby ellipticals to be dM/M ~ 0.2 per Gyr with large uncertainty. We explore the relation between gravitational interaction signatures and the galaxy environment and find that galaxies in clusters are less disturbed than group and field galaxies. We also study how these interactions affect the broadband colors of ellipticals and find a moderate correlation, suggesting that the mergers are not accompanied by significant star formation. Finally, we find no correlation between active galactic nucleus activity, as measured by 6 cm radio emission, and large-scale tidal distortions. This implies that gravitational interactions are not the only, and perhaps not the most important, trigger of nuclear activity. In summary, we find that elliptical galaxies in groups and low-density environments continue to grow at the present day through mostly dry mergers involving little star formation.
Dark matter effect attributed to the inherent structure of cosmic space

We propose that anomalous gravitational effects currently attributed to dark matter can alternatively be explained as a manifestation of the inherent structure of space at galactic length scales. S...
Syllabification by phone categorization

Syllables play an important role in speech synthesis, speech recognition, and spoken document retrieval. A novel, low cost, and language agnostic approach to dividing words into their corresponding syllables is presented. A hybrid genetic algorithm constructs a categorization of phones optimized for syllabification. This categorization is used on top of a hidden Markov model sequence classifier to find syllable boundaries. The technique shows promising preliminary results when trained and tested on English words.
Extremal laws for the real Ginibre ensemble

The real Ginibre ensemble refers to the family of $n\times n$ matrices in which each entry is an independent Gaussian random variable of mean zero and variance one. Our main result is that the appropriately scaled spectral radius converges in law to a Gumbel distribution as $n\rightarrow\infty$. This fact has been known to hold in the complex and quaternion analogues of the ensemble for some time, with simpler proofs. Along the way we establish a new form for the limit law of the largest real eigenvalue.
Coresets for Regressions with Panel Data

This paper introduces the problem of coresets for regression problems to panel data settings. We first define coresets for several variants of regression problems with panel data and then present efficient algorithms to construct coresets of size that depend polynomially on 1/$\varepsilon$ (where $\varepsilon$ is the error parameter) and the number of regression parameters - independent of the number of individuals in the panel data or the time units each individual is observed for. Our approach is based on the Feldman-Langberg framework in which a key step is to upper bound the "total sensitivity" that is roughly the sum of maximum influences of all individual-time pairs taken over all possible choices of regression parameters. Empirically, we assess our approach with synthetic and real-world datasets; the coreset sizes constructed using our approach are much smaller than the full dataset and coresets indeed accelerate the running time of computing the regression objective.
Magnetization switching in nanoscale ferromagnetic grains: description by a kinetic Ising model

The magnetic relaxation of ferromagnetic powders has been studied for many years, largely due to its importance to recording technologies. However, only recently have experiments been performed that resolve the magnetic state of individual sub-micron particles. Motivated by these experimental developments, we use droplet theory and Monte Carlo simulations to study the time and field dependence of some quantities that can be observed by magnetic force microscopy. Particular emphasis is placed on the effects of finite particle size. The qualitative agreement between experiments on switching and our simulations in individual single-domain ferromagnets suggests that the switching mechanism in such particles may involve local nucleation and subsequent growth of droplets of the stable phase.
Improving the Convergence of Reversible Samplers

In Monte-Carlo methods the Markov processes used to sample a given target distribution usually satisfy detailed balance, i.e. they are time-reversible. However, relatively recent results have demonstrated that appropriate reversible and irreversible perturbations can accelerate convergence to equilibrium. In this paper we present some general design principles which apply to general Markov processes. Working with the generator of Markov processes, we prove that for some of the most commonly used performance criteria, i.e., spectral gap, asymptotic variance and large deviation functionals, sampling is improved for appropriate reversible and irreversible perturbations of some initially given reversible sampler. Moreover we provide specific constructions for such reversible and irreversible perturbations for various commonly used Markov processes, such as Markov chains and diffusions. In the case of diffusions, we make the discussion more specific using the large deviations rate function as a measure of performance.
New mechanisms of gauge-mediated supersymmetry breaking

Abstract New mechanisms for the communication of supersymmetry breaking via gauge interactions are introduced. These models do not require complicated dynamics to induce a non-vanishing F term for a singlet. The first class of models communicates supersymmetry breaking to the visible sector through a “mediator” field that transforms under both a messenger gauge group of the dynamical supersymmetry breaking sector and the standard model gauge group. This model has a distinctive phenomenology; in particular, the scalar superpartners should be heavier than the gaugino superpartners by at least an order of magnitude. The second class of models has a phenomenology more similar to the “standard” messenger sectors. A singlet is incorporated, but the model does not require complicated mechanisms to generate a singlet F term. The role of the singlet is to couple fields from the dynamical symmetry breaking sector to fields transforming under the standard model gauge group. We also mention a potential solution to the μ problem.
Study of dipole moments of LiSr and KRb molecules by quantum Monte Carlo methods

Heteronuclear dimers are of significant interest to experiments seeking to exploit ultracold polar molecules in a number of novel ways, including precision measurement, quantum computing and quantum simulation. We calculate highly accurate Born–Oppenheimer total energies and electric dipole moments as a function of internuclear separation for two such dimers, LiSr and KRb. We apply fully correlated, high-accuracy quantum Monte Carlo methods for evaluating these molecular properties in a many-body framework. We use small-core effective potentials combined with multi-reference Slater–Jastrow trial wave functions to provide accurate nodes for the fixed-node diffusion Monte Carlo method. For reference and comparison, we calculate the same properties with Hartree–Fock and with restricted Configuration Interaction methods, and carefully assess the impact of the recovered many-body correlations on the calculated quantities. For LiSr, we find a highly non-linear dipole moment curve, which may make this molecule’s...
A tower connecting gauge groups to string topology

We develop a variant of calculus of functors, and use it to relate the gauge group G(P) of a principal bundle P over M to the Thom ring spectrum (P^Ad)^{-TM}. If P has contractible total space, the resulting Thom ring spectrum is LM^{-TM}, which plays a central role in string topology. R.L. Cohen and J.D.S. Jones have recently observed that, in a certain sense, (P^Ad)^{-TM} is the linear approximation of G(P). We prove an extension of that relationship by demonstrating the existence of higher-order approximations and calculating them explicitly. This also generalizes calculations done by G. Arone.
Longitudinal Pooling & Consistency Regularization to Model Disease Progression From MRIs

Many neurological diseases are characterized by gradual deterioration of brain structure andfunction. Large longitudinal MRI datasets have revealed such deterioration, in part, by applying machine and deep learning to predict diagnosis. A popular approach is to apply Convolutional Neural Networks (CNN) to extract informative features from each visit of the longitudinal MRI and then use those features to classify each visit via Recurrent Neural Networks (RNNs). Such modeling neglects the progressive nature of the disease, which may result in clinically implausible classifications across visits. To avoid this issue, we propose to combine features across visits by coupling feature extraction with a novel longitudinal pooling layer and enforce consistency of the classification across visits in line with disease progression. We evaluate the proposed method on the longitudinal structural MRIs from three neuroimaging datasets: Alzheimer's Disease Neuroimaging Initiative (ADNI, $N=404$ ), a dataset composed of 274 normal controls and 329 patients with Alcohol Use Disorder (AUD), and 255 youths from the National Consortium on Alcohol and NeuroDevelopment in Adolescence (NCANDA). In allthree experiments our method is superior to other widely used approaches for longitudinal classification thus making a unique contribution towards more accurate tracking of the impact of conditions on the brain. The code is available at https://github.com/ouyangjiahong/longitudinal-pooling .
MIT shocks imply market incompleteness

Abstract The allocation after an unanticipated event (often called an “MIT shock”) is different from the allocation of a corresponding complete-market model that explicitly considers the possibility of the shock, even when the probability of the event approaches zero.
Impact of Working Capital Management on Firm’s Profitability: A Study on Listed Companies in Sri Lanka

Aims: The main aim of the study is to identify whether working capital management has an impact on firm’s profitability of listed companies in Sri Lanka. Place and Duration of Study: Pooled panel data of 95 listed companies from 18 sectors are listed on the Colombo Stock Exchange (CSE) which comprised of 475 observations is used during the period of 2012/2013 to 2016/2017. Methodology:Descriptive statistics, Pearson’s Correlation analysis, ANOVA, and Pooled Regression analysis were employed as measures of analysis. Working capital management components and working capital policies are used as independent variables which comprised of number of days of account receivable (DAR), number of days of inventories (DI), number of days of account payables (DAP), cash conversion cycle (CCC), working capital investment policies (WCIP), and working capital financing policies (WCFP). Current ratio (CR), firm size (SIZE), sales growth (GROWTH), and Debt ratio (DR) were employed as controlled variables. Gross operating profit (GOP) and Return on assets (ROA) were used as dependent variable. Results:In the descriptive statistics, average of DAR, DI, DAP, and CCC are 64, 63, 97, and 29 days respectively. The average WCIP and WCFP are indicated as 40% and 27% of total assets. For control variables, the average CR, SIZE, GROWTH, and DR are indicated as 2.27, 14.50, 33% and 40%. In the Pearson correlation analysis, CCC has negative relationship with GOP and ROA. With regard to WCIP and WCFP, there are negative significant relationships with GOP and ROA. Regression analysis states that working capital management significantly impacts on firm’s profitability of listed companies in Sri Lanka. Conclusion:These findings would be useful to consider on maintaining optimal working capital management components and policies to avoid corporate collapse and to maximize firm’s profitability.
Towards a classification of rank r$ \mathcal{N} $ = 2 SCFTs. Part II. Special Kahler stratification of the Coulomb branch

We study the stratification of the singular locus of four dimensional $$ \mathcal{N} $$ = 2 Coulomb branches. We present a set of self-consistency conditions on this stratification which can be used to extend the classification of scale-invariant rank 1 Coulomb branch geometries to two complex dimensions, and beyond. The calculational simplicity of the arguments presented here stems from the fact that the main ingredients needed — the rank 1 deformation patterns and the pattern of inclusions of rank 2 strata — are discrete topological data which satisfy strong self-consistency conditions through their relationship to the central charges of the SCFT. This relationship of the stratification data to the central charges is used here, but is derived and explained in a companion paper [1] by one of the authors. We illustrate the use of these conditions by re-analyzing many previously-known examples of rank 2 SCFTs, and also by finding examples of new theories. The power of these conditions stems from the fact that for Coulomb branch stratifications a conjecturally complete list of physically allowed “elementary slices” is known. By contrast, constraining the possible elementary slices of symplectic singularities relevant for Higgs branch stratifications remains an open problem.
Control for multifunctionality: bioinspired control based on feeding in Aplysia californica

Animals exhibit remarkable feats of behavioral flexibility and multifunctional control that remain challenging for robotic systems. The neural and morphological basis of multifunctionality in animals can provide a source of bioinspiration for robotic controllers. However, many existing approaches to modeling biological neural networks rely on computationally expensive models and tend to focus solely on the nervous system, often neglecting the biomechanics of the periphery. As a consequence, while these models are excellent tools for neuroscience, they fail to predict functional behavior in real time, which is a critical capability for robotic control. To meet the need for real-time multifunctional control, we have developed a hybrid Boolean model framework capable of modeling neural bursting activity and simple biomechanics at speeds faster than real time. Using this approach, we present a multifunctional model of Aplysia californica feeding that qualitatively reproduces three key feeding behaviors (biting, swallowing, and rejection), demonstrates behavioral switching in response to external sensory cues, and incorporates both known neural connectivity and a simple bioinspired mechanical model of the feeding apparatus. We demonstrate that the model can be used for formulating testable hypotheses and discuss the implications of this approach for robotic control and neuroscience.
Marchenko–Pastur law with relaxed independence conditions

We prove the Marchenko–Pastur law for the eigenvalues of p × p sample covariance matrices in two new situations where the data does not have independent coordinates. In the first scenario — the blo...
GIS-Based Estimation of Seasonal Solar Energy Potential for Parking Lots and Roads

The amount of sun cast on roads and parking lots determines the charging opportunities for solar vehicles and impacts the efficiency of conventional vehicles. Estimates of solar energy potential on urban surfaces to assess parking and driving conditions need to account for the shadows cast by surrounding trees and buildings. However, though existing GIS tools can calculate solar potential on surfaces that have buildings and trees, these tools do not estimate the conditions beneath trees and do not consider the seasonal changes in deciduous trees. We introduce a new approach to address these factors using pixel substitution and a light penetration factor. In this paper, we describe how to integrate these techniques into a workflow for computing solar potential estimates for parking and driving conditions. We demonstrate the methodology in an urban setting in North Carolina that includes a mixture of urban structures and trees. We provide code samples so that this workflow is easily repeatable. The solar maps produced with our method are a useful resource for planning solar vehicle parking and routing, and identifying shaded conditions for conventional vehicles.
QCD resummation on single hadron transverse momentum distribution with the thrust axis

We derive the transverse momentum dependent (TMD) factorization and resummation formula of the unpolarized transverse momentum distribution (jT) for the single hadron production with the thrust axis in an electron-positron collision. Two different kinematic regions are considered, including small transverse momentum limit jT « Q, and joint transverse momentum and threshold limit jT « Q(1 − zh) « Q, where Q and zh are the hard scattering energy and the observed hadron momentum fraction. Using effective theory methods, we resum logarithms ln(Q/jT) and ln(1 − zh) to all orders. In the end, we present the differential cross sections and Gaussian widths calculated for the inclusive charged pion production and find that our results are consistent with the measurements reported by the Belle collaboration.