cssi/SciSciGPT-SciSciNet huggingface dataset:
Optomechanical Sensing in the Nonlinear Saturation Limit

The dynamic range of optomechanical-displacement measurement is limited by the nonlinearity of the cavity transmission. We demonstrate that the dynamic range can be made arbitrarily large within a small detection bandwidth in the resolved-sideband regime.
Review of COVID-19 Antibody Therapies

In the global health emergency caused by coronavirus disease 2019 (COVID-19), efficient and specific therapies are urgently needed. Compared with traditional small-molecular drugs, antibody therapies are relatively easy to develop; they are as specific as vaccines in targeting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2); and they have thus attracted much attention in the past few months. This article reviews seven existing antibodies for neutralizing SARS-CoV-2 with 3D structures deposited in the Protein Data Bank (PDB). Five 3D antibody structures associated with the SARS-CoV spike (S) protein are also evaluated for their potential in neutralizing SARS-CoV-2. The interactions of these antibodies with the S protein receptor-binding domain (RBD) are compared with those between angiotensin-converting enzyme 2 and RBD complexes. Due to the orders of magnitude in the discrepancies of experimental binding affinities, we introduce topological data analysis, a variety of network models, and deep learning to analyze the binding strength and therapeutic potential of the 14 antibody–antigen complexes. The current COVID-19 antibody clinical trials, which are not limited to the S protein target, are also reviewed.
Chiral smoothings of knots

Can smoothing a single crossing in a diagram for a knot convert it into a diagram of the knot's mirror image? Zekovic found such a smoothing for the torus knot T(2, 5), and Moore–Vazquez proved that such smoothings do not exist for other torus knots T(2, m) with m odd and square free. The existence of such a smoothing implies that K # K bounds a Mobius band in B4. We use Casson–Gordon theory to provide new obstructions to the existence of such chiral smoothings. In particular, we remove the constraint that m be square free in the Moore–Vazquez theorem, with the exception of m = 9, which remains an open case. Heegaard Floer theory provides further obstructions; these do not give new information in the case of torus knots of the form T(2, m), but they do provide strong constraints for other families of torus knots. A more general question asks, for each pair of knots K and J, what is the minimum number of smoothings that are required to convert a diagram of K into one for J. The methods presented here can be applied to provide lower bounds on this number.
A Thom isomorphism in foliated de Rham theory

Abstract We prove a Thom isomorphism theorem for differential forms in the setting of transverse Lie algebra actions on foliated manifolds and foliated vector bundles.
Remorseful Returns: What to Do With Returned Surface-Collected Items From National Park Service Units:

Surface-collected artifacts, and natural features for that matter, have been and are being stolen from public lands by visitors. Some are returned, often with remorseful letters. Most of the return...
Topological generation of special linear groups

Abstract Let C 1 , … , C e be noncentral conjugacy classes of the algebraic group G = S L n ( k ) defined over a sufficiently large field k, and let Ω : = C 1 × … × C e . This paper determines necessary and sufficient conditions for the existence of a tuple ( x 1 , … , x e ) ∈ Ω such that 〈 x 1 , … , x e 〉 is Zariski dense in G. As a consequence, a new result concerning generic stabilizers in linear representations of algebraic groups is proved, and existing results on random ( r , s ) -generation of finite groups of Lie type are strengthened.
The state, religion, and freedom: a review essay of Persecution & toleration

Persecution and Toleration offers a novel and superb analysis of the birth of religious freedom. Rather than seek an ideational account of the rise of religious freedom, Johnson and Koyama investigate changes in the institutional environment that governed the relationship between religion and the state. These changes made it in the interest of policy makers in modern Europe to grant greater religious freedom by transitioning from identity rules to impersonal laws in maintaining order. The book introduces a new thought-provoking conceptual framework that can be extended to examine the complicated history of the state’s interaction with religion, comparative analysis of the relationship between state capacity and political legitimacy, and various other issues concerning the treatment of minorities and heterodox practices around the world.
Perspective: Nonequilibrium dynamics of localized and delocalized excitons in colloidal quantum dot solids

Self-assembled quantum dot (QD) solids are a highly tunable class of materials with a wide range of applications in solid-state electronics and optoelectronic devices. In this perspective, the authors highlight how the presence of microscopic disorder in these materials can influence their macroscopic optoelectronic properties. Specifically, they consider the dynamics of excitons in energetically disordered QD solids using a theoretical model framework for both localized and delocalized excitonic regimes. In both cases, they emphasize the tendency of energetic disorder to promote nonequilibrium relaxation dynamics and discuss how the signatures of these nonequilibrium effects manifest in time-dependent spectral measurements. Moreover, they describe the connection between the microscopic dynamics of excitons within the material and the measurement of material specific parameters, such as emission linewidth broadening and energetic dissipation rate.
THE STRUCTURE OF THE EVOLVED CIRCUMBINARY DISK AROUND V4046 Sgr

We present sensitive, sub-arcsecond resolution Submillimeter Array observations of the protoplanetary disk around the nearby, pre-main sequence spectroscopic binary V4046 Sgr. We report for the first time a large inner hole (r = 29 AU) spatially resolved in the 1.3 mm continuum emission and study the structure of this disk using radiative transfer calculations to model the spectral energy distribution, continuum visibilities, and spectral line emission of CO and its main isotopologues. Our modeling scheme demonstrates that the majority of the dust mass is distributed in a narrow ring (centered at 37 AU with a FWHM of 16 AU) that is ~5× more compact than the gas disk. This structure implies that the dust-to-gas mass ratio has a strong spatial variation, ranging from a value much larger than typical of the interstellar medium (ISM) at the ring to much smaller than that of the ISM at larger disk radii. We suggest that these basic structural features are potentially observational signatures of the accumulation of solids at a local gas pressure maximum. These models also require a substantial population of ~μm sized grains inside the central disk cavity. We suggest that this structure is likely the result of dynamical interactions with a low-mass companion, although photoevaporation may also play a secondary role.
Optimal hashing-based time-space trade-offs for approximate near neighbors

We show tight upper and lower bounds for time-space trade-offs for the c-approximate Near Neighbor Search problem. For the d-dimensional Euclidean space and n-point datasets, we develop a data structure with space n1+ρu+o(1) + O(dn) and query time nρq+o(1) + dno(1) for every ρu, ρq ≥ 0 with:[EQUATION]In particular, for the approximation c = 2 we get:• Space n1.77 ... and query time no(1), significantly improving upon known data structures that support very fast queries [IM98, KOR00];• Space n1.14... and query time n0.14..., matching the optimal data-dependent Locality-Sensitive Hashing (LSH) from [AR15];• Space n1+o(1) and query time n0.43..., making significant progress in the regime of near-linear space, which is arguably of the most interest for practice [LJW+07].This is the first data structure that achieves sublinear query time and near-linear space for every approximation factor c > 1, improving upon [Kap15]. The data structure is a culmination of a long line of work on the problem for all space regimes; it builds on Spherical Locality-Sensitive Filtering [BDGL16] and data-dependent hashing [AINR14, AR15].Our matching lower bounds are of two types: conditional and unconditional. First, we prove tightness of the whole trade-off (0.1) in a restricted model of computation, which captures all known hashing-based approaches. We then show unconditional cell-probe lower bounds for one and two probes that match (0.1) for ρq = 0, improving upon the best known lower bounds from [PTW10]. In particular, this is the first space lower bound (for any static data structure) for two probes which is not polynomially smaller than the one-probe bound. To show the result for two probes, we establish and exploit a connection to locally-decodable codes.
Investigating reciprocity failure in 1.7-micron cut-off HgCdTe detectors

Flux dependent non-linearity (reciprocity failure) in HgCdTe NIR detectors with 1.7 μm cut-off was investigated. A dedicated test station was designed and built to measure reciprocity failure over the full dynamic range of near infrared detectors. For flux levels between 1 and 100,000 photons/sec a limiting sensitivity to reciprocity failure of 0.3 %/decade was achieved. First measurements on several engineering grade 1.7 μm cut-off HgCdTe detectors show a wide range of reciprocity failure, from less than 0.5 %/decade to about 10%/decade. For at least two of the tested detectors, significant spatial variation in the effect was observed. No indication for wavelength dependency was found. The origin of reciprocity failure is currently not well understood. In this paper we present details of our experimental set-up and show the results of measurements for several detectors.
Global identifiability of linear structural equation models

Structural equation models are multivariate statistical models that are defined by specifying noisy functional relationships among random variables. We consider the classical case of linear relationships and additive Gaussian noise terms. We give a necessary and sufficient condition for global identifiability of the model in terms of a mixed graph encoding the linear structural equations and the correlation structure of the error terms. Global identifiability is understood to mean injectivity of the parametrization of the model and is fundamental in particular for applicability of standard statistical methodology.
Jet-induced 2-D crater formation with horizontal symmetry breaking

We investigate the formation of a crater in a 2-D bed of granular material by a jet of impinging gas, motivated by the problem of a retrograde rocket landing on a planetary surface. The crater is characterized in terms of depth and shape as it evolves, as well as by the horizontal position of the bottom of the crater. The crater tends to grow logarithmically in time, a result which is common in related experiments. We also observe a horizontal symmetry breaking at certain well-defined conditions which, as we will demonstrate, could be of considerable practical concern for lunar or planetary landers. We present data on the evolution of these asymmetric states and attempt to give insights into the mechanism behind the symmetry-breaking bifurcation.
Hessian eigenvalue distribution in a random Gaussian landscape

The energy landscape of multiverse cosmology is often modeled by a multi-dimensional random Gaussian potential. The physical predictions of such models crucially depend on the eigenvalue distribution of the Hessian matrix at potential minima. In particular, the stability of vacua and the dynamics of slow-roll inflation are sensitive to the magnitude of the smallest eigenvalues. The Hessian eigenvalue distribution has been studied earlier, using the saddle point approximation, in the leading order of 1/N expansion, where N is the dimensionality of the landscape. This approximation, however, is insufficient for the small eigenvalue end of the spectrum, where sub-leading terms play a significant role. We extend the saddle point method to account for the sub-leading contributions. We also develop a new approach, where the eigenvalue distribution is found as an equilibrium distribution at the endpoint of a stochastic process (Dyson Brownian motion). The results of the two approaches are consistent in cases where both methods are applicable. We discuss the implications of our results for vacuum stability and slow-roll inflation in the landscape.
Mapping Distances across the Perseus Molecular Cloud Using CO Observations, Stellar Photometry, and Gaia DR2 Parallax Measurements

Author(s): Zucker, C; Schlafly, EF; Speagle, JS; Green, GM; Portillo, SKN; Finkbeiner, DP; Goodman, AA | Abstract: We present a new technique to determine distances to major star-forming regions across the Perseus Molecular Cloud, using a combination of stellar photometry, astrometric data, and 12CO spectral-line maps. Incorporating the Gaia DR2 parallax measurements when available, we start by inferring the distance and reddening to stars from their Pan-STARRS1 and Two Micron All Sky Survey photometry, based on a technique presented by Green et al. and implemented in their 3D "Bayestar" dust map of three-quarters of the sky. We then refine their technique by using the velocity slices of a CO spectral cube as dust templates and modeling the cumulative distribution of dust along the line of sight toward these stars as a linear combination of the emission in the slices. Using a nested sampling algorithm, we fit these per-star distance-reddening measurements to find the distances to the CO velocity slices toward each star-forming region. This results in distance estimates explicitly tied to the velocity structure of the molecular gas. We determine distances to the B5, IC 348, B1, NGC 1333, L1448, and L1451 star-forming regions and find that individual clouds are located between ≈275 and 300 pc, with typical combined uncertainties of ≈5%. We find that the velocity gradient across Perseus corresponds to a distance gradient of about 25 pc, with the eastern portion of the cloud farther away than the western portion. We determine an average distance to the complex of 294 ± 17 pc, about 60 pc further than the distance derived to the western portion of the cloud using parallax measurements of water masers associated with young stellar objects. The method we present is not limited to the Perseus Complex, but may be applied anywhere on the sky with adequate CO data in the pursuit of more accurate 3D maps of molecular clouds in the solar neighborhood and beyond.
Existence, Stability and Dynamics of Discrete Solitary Waves in a Binary Waveguide Array

Recent work has explored binary waveguide arrays in the long-wavelength, near-continuum limit, here we examine the opposite limit, namely the vicinity of the so-called anti-continuum limit. We provide a systematic discussion of states involving one, two and three excited waveguides, and provide comparisons that illustrate how the stability of these states differ from the monoatomic limit of a single type of waveguide. We do so by developing a general theory which systematically tracks down the key eigenvalues of the linearized system. When we find the states to be unstable, we explore their dynamical evolution through direct numerical simulations. The latter typically illustrate, for the parameter values considered herein, the persistence of localized dynamics and the emergence for the duration of our simulations of robust quasi-periodic states for two excited sites. As the number of excited nodes increases, the unstable dynamics feature less regular oscillations of the solution's amplitude.
A Selective Review of Group Selection in High-Dimensional Models

Grouping structures arise naturally in many statistical modeling problems. Several methods have been proposed for variable selection that respect grouping structure in variables. Examples include the group LASSO and several concave group selection methods. In this article, we give a selective review of group selection concerning methodological developments, theoretical properties and computational algorithms. We pay particular attention to group selection methods involving concave penalties. We address both group selection and bi-level selection methods. We describe several applications of these methods in nonparametric additive models, semiparametric regression, seemingly unrelated regressions, genomic data analysis and genome wide association studies. We also highlight some issues that require further study.
Infrared Spectroscopy of HR 4796A's Bright Outer Cometary Ring + Tenuous Inner Hot Dust Cloud

We have obtained new NASA IRTF SpeX spectra of the HR 4796A debris ring system. We find a unique red excess flux that extends out to ~9 um in Spitzer IRS spectra, where thermal emission from cold, ~100K dust from the system's ring at ~75 AU takes over. Matching imaging ring photometry, we find the excess consists of NIR reflectance from the ring which is as red as that of old, processed comet nuclei, plus a tenuous thermal emission component from close-in, T ~ 850 K circumstellar material evincing an organic plus silicate emission feature complex at 7 - 13 um. Unusual, emission-like features due to atomic Si, S, Ca, and Sr were found at 0.96 - 1.07 um, likely sourced by rocky dust evaporating in the 850 K component. An empirical cometary dust phase function can reproduce the scattered light excess and 1:5 balance of scattered vs. thermal energy for the ring with optical depth Tau > 0.10 in an 8 AU wide belt of 4 AU vertical height and Mdust > 0.1-0.7 M_Mars. Our results are consistent with HR 4796A consisting of a narrow sheparded ring of devolatilized cometary material associated with multiple rocky planetesimal subcores, and a small steady stream of dust inflowing from this belt to a rock sublimation zone at approximately 1 AU from the primary. These subcores were built from comets that have been actively emitting large, reddish dust for > 0.4 Myr at 100K, the temperature at which cometary activity onset is seen in our Solar System.
Timing Noise Properties of GRO J0422+32

OSSE observed the transient black hole candidate GRO J0422+32 (XN Persei 92) between 1992 August 11 and 1992 September 17. High time resolution data were obtained in several energy bands over the 35-600 keV range with a timing resolution of 8 ms. Power spectra at energies below 175 keV show substantial low-frequency red noise with a shoulder at a few times 10−2 Hz, peaked noise with characteristic frequency near 0.2 Hz, and a second shoulder at a few Hz. The frequencies of the shoulders and the peak are independent of energy and source intensity. The complex cross spectrum indicates that photons in the 75-175 keV band lag photons in the 35-60 keV band by a time roughly proportional to the inverse of the Fourier frequency. The maximum lag observed is 300 ms. The power and lag spectra are consistent with the production of the γ-rays through thermal Comptonization in an extended hot corona with a power-law density profile.
Privacy threats in intimate relationships

This article provides an overview of intimate threats: a class of privacy threats that can arise within our families, romantic partnerships, close friendships, and caregiving relationships. Many common assumptions about privacy are upended in the context of these relationships, and many otherwise effective protective measures fail when applied to intimate threats. Those closest to us know the answers to our secret questions, have access to our devices, and can exercise coercive power over us. We survey a range of intimate relationships and describe their common features. Based on these features, we explore implications for both technical privacy design and policy, and offer design recommendations for ameliorating intimate privacy risks.
Investigating the Uniformity of the Excess Gamma rays towards the Galactic Center Region

Author(s): Horiuchi, S; Kaplinghat, M; Kwa, A | Abstract: We perform a composite likelihood analysis of subdivided regions within the central 26° × 20° of the Milky Way, with the aim of characterizing the spectrum of the gamma-ray galactic center excess in regions of varying galactocentric distance. Outside of the innermost few degrees, we find that the radial profile of the excess is background-model dependent and poorly constrained. The spectrum of the excess emission is observed to extend upwards of 10 GeV outside ∼5° in radius, but cuts off steeply between 10-20 GeV only in the innermost few degrees. If interpreted as a real feature of the excess, this radial variation in the spectrum has important implications for both astrophysical and dark matter interpretations of the galactic center excess. Single-component dark matter annihilation models face challenges in reproducing this variation; on the other hand, a population of unresolved millisecond pulsars contributing both prompt and secondary inverse Compton emission may be able to explain the spectrum as well as its spatial dependency. We show that the expected differences in the photon-count distributions of a smooth dark matter annihilation signal and an unresolved point source population are an order of magnitude smaller than the fluctuations in residuals after fitting the data, which implies that mismodeling is an important systematic effect in point source analyses aimed at resolving the gamma-ray excess.
A MATHEMATICAL MODEL OF PLATELET AGGREGATION IN AN EXTRAVASCULAR INJURY UNDER FLOW

We present the first mathematical model of flow-mediated primary hemostasis in an extravascular injury which can track the process from initial deposition to occlusion. The model consists of a system of ordinary differential equations (ODEs) that describe platelet aggregation (adhesion and cohesion), soluble-agonist-dependent platelet activation, and the flow of blood through the injury. The formation of platelet aggregates increases resistance to flow through the injury, which is modeled using the Stokes-Brinkman equations. Data from analogous experimental (microfluidic flow) and partial differential equation models informed parameter values used in the ODE model description of platelet adhesion, cohesion, and activation. This model predicts injury occlusion under a range of flow and platelet activation conditions. Simulations testing the effects of shear and activation rates resulted in delayed occlusion and aggregate heterogeneity. These results validate our hypothesis that flow-mediated dilution of activating chemical adenosine diphosphate hinders aggregate development. This novel modeling framework can be extended to include more mechanisms of platelet activation as well as the addition of the biochemical reactions of coagulation, resulting in a computationally efficient high throughput screening tool of primary and secondary hemostasis.
Frequency Measurements of Superradiance from the Strontium Clock Transition

The frequency stability of superradiant light emitted from an optical clock transition in cold strontium atoms surpasses that of active microwave atomic clocks, paving the way for a next generation of high-precision optical frequency references to be used outside the laboratory environment.
Accurate Group-Delay Measurement for Radial-Velocity Instruments Using the Dispersed Fixed-Delay Interferometer Method

The dispersed fixed-delay Intereferometer (DFDI) method is attractive for its low cost, compact size, and multiobject capability in precision radial-velocity (RV) measurements. The phase shift of fringes of stellar absorption lines is measured and then converted to an RV shift via an important parameter, phase-to-velocity scale (PV scale), determined by the group delay (GD) of a fixed-delay interferometer. Two methods of GD measurement using a DFDI Doppler instrument are presented in this article: (1) GD measurement using white-light combs generated by the fixed-delay interferometer and (2) GD calibration using an RV reference star. These two methods provide adequate precision of GD measurement and calibration, given the current RV precision achieved by a DFDI Doppler instrument. They can potentially be used to measure GD of an fixed-delay interferometer for submeter-precision Doppler measurement with a DFDI instrument. Advantages and limitations of each method are discussed in detail. The two methods can serve as standard procedures of PV-scale calibration for DFDI instruments and cross-checks for each other.
High Precision Numerical Computation of Principal Points for Univariate Distributions

Principal points were first introduced in 1990: for a positive integer n, n principal points of a random variable are the n points that minimize the mean squared distance between the random variable and the nearest of the n points. In this paper, we give a high precision numerical method for calculating the n principal points and the n th quantization errors for all positive integers n. For some absolutely continuous univariate distributions, we calculate the n principal points for different n using Newton’s method. Additionally, we also provide the corresponding values of mean squared distances.
Pixelated VLC-Backscattering for Self-Charging Indoor IoT Devices

Visible light communication (VLC) backscatter has been proposed as a wireless access option for Internet of Things. However, the throughput of the state-of-the-art VLC backscatter is limited by simple single-carrier pulsed modulation scheme, such as ON-OFF keying (OOK). In this letter, a novel pixelated VLC backscatter is proposed and implemented to overcome the channel capacity limitation. In particular, multiple smaller VLC backscatters are integrated to generate multi-level signals, which enables the usage of advanced modulation schemes. Based on experimental results, rate adaptation at different communication distances can be employed to enhance the achievable data rate. Compared with OOK, the data rate can be tripled, when 8-pulse amplitude modulation is used at 2 m. In general, $n$ -fold throughput enhancement is realized by utilizing $n$ smaller VLC backscatters, while incurring negligible additional energy using the same device space as that of a single large backscatter.
Galactic Cosmic-Ray Anisotropies: Voyager 1 in the Local Interstellar Medium

Since crossing the heliopause on 2012 August 25, Voyager 1 observed reductions in galactic cosmic ray count rates caused by a time-varying depletion of particles with pitch angles near 90?, while intensities of particles with other pitch angles remain unchanged. Between late 2012 and mid-2017, three large-scale events occurred, lasting from ~100 to ~630 days. Omnidirectional and directional high-energy data from Voyager 1's Cosmic Ray Subsystem are used to report cosmic ray intensity variations. Omnidirectional (20 MeV) proton-dominated measurements show up to a 3.8% intensity reduction. Bidirectional (70 MeV) proton-dominated measurements taken from various spacecraft orientations provide insight about the depletion region's spatial properties. We characterize the anisotropy as a "notch" in an otherwise uniform pitch angle distribution of varying depth and width centered about 90? in pitch angle space. The notch averages 22? wide and 15% deep, signifying a depletion region that is broad and shallow. There are indications that the anisotropy is formed by a combination of magnetic trapping and cooling downstream of solar-induced transient disturbances in a region that is also likely influenced by the highly compressed fields near the heliopause.
ON THE BEHAVIOR OF TEST IDEALS UNDER FINITE MORPHISMS

We derive transformation rules for test ideals and F-singularities under an arbi- trary finite surjective morphism �: Y ! X of normal varieties in prime characteristic p > 0. The main technique is to relate homomorphisms FOX ! OX, such as Frobenius splittings, to homomorphisms FOY ! OY . In the simplest cases, these rules mirror transforma- tion rules for multiplier ideals in characteristic zero. As a corollary, we deduce sufficient conditions which imply that trace is surjective, i.e. TrY=X(��OY ) = OX.
Overfitting Can Be Harmless for Basis Pursuit, But Only to a Degree

Recently, there have been significant interests in studying the so-called "double-descent" of the generalization error of linear regression models under the overparameterized and overfitting regime, with the hope that such analysis may provide the first step towards understanding why overparameterized deep neural networks (DNN) still generalize well. However, to date most of these studies focused on the min $\ell_2$-norm solution that overfits the data. In contrast, in this paper we study the overfitting solution that minimizes the $\ell_1$-norm, which is known as Basis Pursuit (BP) in the compressed sensing literature. Under a sparse true linear regression model with $p$ i.i.d. Gaussian features, we show that for a large range of $p$ up to a limit that grows exponentially with the number of samples $n$, with high probability the model error of BP is upper bounded by a value that decreases with $p$. To the best of our knowledge, this is the first analytical result in the literature establishing the double-descent of overfitting BP for finite $n$ and $p$. Further, our results reveal significant differences between the double-descent of BP and min $\ell_2$-norm solutions. Specifically, the double-descent upper-bound of BP is independent of the signal strength, and for high SNR and sparse models the descent-floor of BP can be much lower and wider than that of min $\ell_2$-norm solutions.
AdS flowing black funnels: Stationary AdS black holes with non-Killing horizons and heat transport in the dual CFT

We construct stationary non-equilibrium black funnels locally asymptotic to global AdS4 in vacuum Einstein–Hilbert gravity with a negative cosmological constant. These are non-compactly-generated black holes in which a single connected bulk horizon extends to meet the conformal boundary. Thus the induced (conformal) boundary metric has smooth horizons as well. In our examples, the boundary spacetime contains a pair of black holes connected through the bulk by a tubular bulk horizon. Taking one boundary black hole to be hotter than the other (ΔT ≠ 0) prohibits equilibrium. The result is a so-called flowing funnel, a stationary bulk black hole with a non-Killing horizon that may be said to transport heat toward the cooler boundary black hole. While generators of the bulk future horizon evolve toward zero expansion in the far future, they begin at finite affine parameter with infinite expansion on a singular past horizon characterized by power-law divergences with universal exponents. We explore both the horizon generators and the boundary stress tensor in detail. While most of our results are numerical, a semi-analytic fluid/gravity description can be obtained by passing to a one-parameter generalization of the above boundary conditions. The new parameter detunes the temperatures Tbulk BH and Tbndy BH of the bulk and boundary black holes, and we may then take and ΔT small to control the accuracy of the fluid–gravity approximation. In the small α, ΔT regime, we find excellent agreement with our numerical solutions. For our cases the agreement also remains quite good even for α ~ 0.8. In terms of a dual CFT, our α = 1 solutions describe heat transport via a large N version of Hawking radiation through a deconfined plasma that couples efficiently to both boundary black holes.
Multiwave imaging in an enclosure with variable wave speed

In this paper we consider the mathematical model of thermo- and photo-acoustic tomography for the recovery of the initial condition of a wave field from knowledge of its boundary values. Unlike the free-space setting, we consider the wave problem in a region enclosed by a surface where an impedance boundary condition is imposed. This condition models the presence of physical boundaries such as interfaces or acoustic mirrors which reflect some of the wave energy back into the enclosed domain. By recognizing that the inverse problem is equivalent to a statement of boundary observability, we use control operators to prove the unique and stable recovery of the initial wave profile from knowledge of boundary measurements. Since our proof is constructive, we explicitly derive a solvable equation for the unknown initial condition. This equation can be solved numerically using the conjugate gradient method. We also propose an alternative approach based on the stabilization of waves. This leads to an exponentially and uniformly convergent Neumann series reconstruction when the impedance coefficient is not identically zero. In both cases, if well-known geometrical conditions are satisfied, our approaches are naturally suited for variable wave speed and for measurements on a subset of the boundary.
Stability of the Magnetopause of Disk-Accreting Rotating Stars

We discuss three modes of oscillation of accretion disks around rotating magnetized neutron stars which may explain the separations of the kilohertz quasi-periodic oscillations (QPOs) seen in low-mass X-ray binaries. The existence of these compressible, nonbarotropic magnetohydrodynamic (MHD) modes requires that there be a maximum in the angular velocity Ω(r) of the accreting material larger than the angular velocity of the star Ω*, and that the fluid be in approximately circular motion near this maximum rather than moving rapidly toward the star or out of the disk plane into funnel flows. Such a maximum in Ω occurs naturally in disk accretion to a slowly rotating magnetized star due the magnetic braking of the disk rotation by the stellar field. Our MHD simulations show this type of flow and Ω(r) profile. The first mode is a Rossby wave instability (RWI) mode which is radially trapped in the vicinity of the maximum of a key function at rR . The real part of the angular frequency of the mode is ω r = mΩ(rR ), where m = 1, 2, ... is the azimuthal mode number. We argue that the nonlinear saturation of the RWI occurs when the trapping frequency of fluid particles in the Rossby vortex equals the RWI growth rate. The second mode is a mode driven by the rotating, nonaxisymmetric component of the star's magnetic field. It has an angular frequency equal to the star's angular rotation rate Ω*. This mode is strongly excited near the radius of the Lindblad resonance which is slightly outside of rR . The third mode arises naturally from the interaction of a flow perturbation with the rotating nonaxisymmetric component of the star's magnetic field. It has an angular frequency Ω*/2. We suggest that the first mode with m = 1 is associated with the upper QPO frequency, ν u ; that the nonlinear interaction of the first and second modes gives the lower QPO frequency, νl = ν u – ν*; and that the nonlinear interaction of the first and third modes gives the lower QPO frequency νl = ν u – ν*/2, where ν* = Ω*/2π.
The Use of Unlabeled Data in Predictive Modeling

The incorporation of unlabeled data in regression and classification analysis is an increasing focus of the applied statistics and machine learning literatures, with a number of recent examples demonstrating the potential for unlabeled data to contribute to improved predictive accuracy. The statistical basis for this semisupervised analysis does not appear to have been well delineated; as a result, the underlying theory and rationale may be underappreciated, especially by nonstatisticians. There is also room for statisticians to become more fully engaged in the vigorous research in this important area of intersection of the statistical and computer sciences. Much of the theoretical work in the literature has focused, for example, on geometric and structural properties of the unlabeled data in the context of particular algorithms, rather than probabilistic and statistical questions. This paper overviews the fundamental statistical foundations for predictive modeling and the general questions associated with unlabeled data, highlighting the relevance of venerable concepts of sampling design and prior specification. This theory, illustrated with a series of central illustrative examples and two substantial real data analyses, shows precisely when, why and how unlabeled data matter.
Algebraic degrees of pseudo-Anosov stretch factors

The motivation for this paper is to justify a remark of Thurston that the algebraic degree of stretch factors of pseudo-Anosov maps on a surface S can be as high as the dimension of the Teichmuller space of S. In addition to proving this, we completely determine the set of possible algebraic degrees of pseudo-Anosov stretch factors on almost all finite type surfaces. As a corollary, we find the possible degrees of the number fields that arise as trace fields of Veech groups of flat surfaces homeomorphic to closed orientable surfaces. Our construction also gives an algorithm for finding a pseudo-Anosov map on a given surface whose stretch factor has a prescribed degree. One ingredient of the proofs is a novel asymptotic irreducibility criterion for polynomials.
Phonoemissive spin tunneling in molecular nanomagnets

A new mechanism is proposed for the magnetization reversal of molecular nanomagnets such as Fe8. In this process the spin tunnels from the lowest state near one easy direction to the first excited state near the opposite easy direction, and subsequently decays to the second easy direction with the emission of a phonon, or it first emits a phonon and then tunnels to the final state. This mechanism is the simplest imaginable one that allows magnetization relaxation in the presence of a longitudinal magnetic field that is so large that the nuclear spin environment cannot absorb the energy required for energy conservation to hold. It is proposed as a way of understanding both magnetization realaxation and Landau-Zener-Stuckelberg (LZS) experiments. The requisite Fermi golden rule rate, and the spin-flip rates are calculated. The rates are too low to affect the minima in the LZS tunneling as a function of transverse field, and also somewhat low for relaxation. Thus a full understanding of magnetic relaxation in the experiments remains an open question.
Generating self-map monoids of infinite sets

Let $\Omega$ be a countably infinite set, $S = {\rm Sym}(\Omega)$ the group of permutations of $\Omega$ , and $E = {\rm Self}(\Omega)$ the monoid of self-maps of $\Omega$ . Given two subgroups $G_1, G_2 \subseteq S$ , let us write $G_1 \approx_S G_2$ if there exists a finite subset $U \subseteq S$ such that the groups generated by $G_1 \cup U$ and $G_2 \cup U$ are equal. Bergman and Shelah showed that the subgroups which are closed in the function topology on S fall into exactly four equivalence classes with respect to $\approx_S$ . Letting $\approx$ denote the obvious analog of $\approx_S$ for submonoids of E, we prove an analogous result for a certain class of submonoids of E, from which the theorem for groups can be recovered. Along the way, we show that given two subgroups $G_1, G_2 \subseteq S$ which are closed in the function topology on S, we have $G_1 \approx_S G_2$ if and only if $G_1 \approx G_2$ (as submonoids of E), and that ${\rm cl}_S (G) \approx {\rm cl}_E (G)$ for every subgroup $G \subseteq S $ (where ${\rm cl}_S (G)$ denotes the closure of G in the function topology in S and ${\rm cl}_E (G)$ its closure in the function topology in E).
MICROLENS SURVEYS ARE A POWERFUL PROBE OF ASTEROIDS

While of order of a million asteroids have been discovered, the number in rigorously controlled samples that have precise orbits and rotation periods, as well as well-measured colors, is relatively small. In particular, less than a dozen main-belt asteroids with estimated diameters D < 3 km have excellent rotation periods. We show how existing and soon-to-be-acquired microlensing data can yield a large asteroid sample with precise orbits and rotation periods, which will include roughly 6% of all asteroids with maximum brightness I < 18.1 and lying within 10° of the ecliptic. This sample will be dominated by small and very small asteroids, down to D ~ 1 km. We also show how asteroid astrometry could turn current narrow-angle OGLE proper motions of bulge stars into wide-angle proper motions. This would enable one to measure the proper-motion gradient across the Galactic bar.
A dual to tight closure theory

We introduce an operation on modules over an F -finite ring of characteristic p . We call this operation tight interior . While it exists more generally, in some cases this operation is equivalent to the Matlis dual of tight closure. Moreover, the interior of the ring itself is simply the big test ideal. We directly prove, without appeal to tight closure, results analogous to persistence, colon capturing, and working modulo minimal primes, and we begin to develop a theory dual to phantom homology. Using our dual notion of persistence, we obtain new and interesting transformation rules for tight interiors, and so in particular for the test ideal. Using our theory of phantom homology, we prove a vanishing theorem for maps of Ext. We also compare our theory with Blickle’s notion of Cartier modules, and in the process we prove new existence results for Blickle’s test submodule. Finally, we apply the theory we developed to the study of test ideals in nonnormal rings, proving that the finitistic test ideal coincides with the big test ideal in some cases.
Pseudo‐Anosov stretch factors and homology of mapping tori

We consider the pseudo-Anosov elements of the mapping class group of a surface of genus g that fix a rank k subgroup of the first homology of the surface. We show that the smallest entropy among these is comparable to (k + 1)/g. This interpolates between results of Penner and of Farb and the second and third authors, who treated the cases of k = 0 and k = 2g, respectively, and answers a question of Ellenberg. We also show that the number of conjugacy classes of pseudo-Anosov mapping classes as above grows (as a function of g) like a polynomial of degree k.
An isomorphism extension theorem for Landau-Ginzburg B-models

ABSTRACTLandau-Ginzburg mirror symmetry studies isomorphisms between A- and B-models, which are graded Frobenius algebras that are constructed using a weighted homogeneous polynomial W and a relate...
Surface modes and parity violation in Schwinger model on the lattice

The phase diagram of the Schwinger model on the lattice with Wilson fermions is investigated in the HartreeFock approximation. In case of single flavour (not directly amenable to simulation), the calculation indicates the existence of the parity violating phase at both weak and intermediate-to-strong couplings. Hartree-Fock vacuum sustains a nonzero electric field in this broken phase. The phase structure of the model with two flavours is also discussed.
Universality of large N phase transitions in Wilson loop operators in two and three dimensions

The eigenvalue distribution of a Wilson loop operator of fixed shape undergoes a transition under scaling at infinite N. We derive a large N scaling function in a double scaling limit of the average characteristic polynomial associated with the Wilson loop operator in two dimensional QCD. We hypothesize that the transition in three and four dimensional large N QCD are also in the same universality class and provide a numerical test for our hypothesis in three dimensions.
Reliability-based error detection for feedback communication with low latency

This paper presents a reliability-based decoding scheme for variable-length coding with feedback and demonstrates via simulation that it can achieve higher rates than Polyanskiy et al.'s random coding lower bound for variable-length feedback (VLF) coding on both the BSC and AWGN channel. The proposed scheme uses the reliability output Viterbi algorithm (ROVA) to compute the word error probability after each decoding attempt, which is compared against a target error threshold and used as a stopping criterion to terminate transmission. The only feedback required is a single bit for each decoding attempt, informing the transmitter whether the ROVA-computed word-error probability is sufficiently low. Furthermore, the ROVA determines whether transmission/decoding may be terminated without the need for a rate-reducing CRC.
Zeta-polynomials, Hilbert polynomials, and the Eichler–Shimura identities

Recently, Ono et al. answered problems of Manin by defining zeta-polynomials $$Z_f(s)$$ for even weight newforms $$f\in S_k(\varGamma _0(N)$$ ; these polynomials can be defined by applying the “Rodriguez-Villegas transform” to the period polynomial of f. It is known that these zeta-polynomials satisfy a functional equation $$Z_f(s) = \pm \, Z_f(1-s)$$ and they have a conjectural arithmetic-geometric interpretation. Here, we give analogous results for a slightly larger class of polynomials which are also defined using the Rodriguez–Villegas transform.
Laser cooling of optically trapped molecules

Ultracold molecules are ideal platforms for many important applications, ranging from quantum simulation1–5 and quantum information processing 6,7 to precision tests of fundamental physics2,8–11. Producing trapped, dense samples of ultracold molecules is a challenging task. One promising approach is direct laser cooling, which can be applied to several classes of molecules not easily assembled from ultracold atoms12,13. Here, we report the production of trapped samples of laser-cooled CaF molecules with densities of 8 × 107 cm−3 and at phase-space densities of 2 × 10−9, 35 times higher than for sub-Doppler-cooled samples in free space14. These advances are made possible by efficient laser cooling of optically trapped molecules to well below the Doppler limit, a key step towards many future applications. These range from ultracold chemistry to quantum simulation, where conservative trapping of cold and dense samples is desirable. In addition, the ability to cool optically trapped molecules opens up new paths towards quantum degeneracy. Laser cooling of optically trapped diatomic molecules CaF to sub-Doppler temperatures has been achieved. The technique provides an alternative approach towards the production of ultracold polar molecules.
The formation of globules in planetary nebulae

We discuss the formation of globules in planetary nebulae, typified by those observed in the Helix Nebula. We show that the properties of the globules, their number, mass, separation, and overall geometry strongly support a scenario in which globules are formed by the fragmentation of a swept-up shell as opposed to models in which the knots form in the AGB wind. We show that the RT or other instabilities which lead to the break-up of shells formed in the nebulae by fast winds or ionization fronts can produce arrays of globules with the overall geometry and within the mass range observed. We also show that the presence of a magnetic field in the circumstellar gas may play an important role in controlling the fragmentation process. Using field strengths measured in the precursor AGB envelopes, we find that close to the central star where the fields are relatively strong, the wavelengths of unstable MRT modes are larger than the shell dimensions, and the fragmentation of the shell is suppressed. The wavelength of the most unstable MRT mode decreases with increasing distance from the star, and when it becomes comparable to the shell thickness, it can lead to the sudden, rapid break-up of an accelerating shell. For typical nebula parameters, the model results in numerous fragments with a mass scale and a separation scale similar to those observed. Our results provide a link between global models of PN shaping in which shells form via winds and ionization fronts, and the formation of small scale structures in the nebulae.
Eigenvalues and eigenfunctions of two coupled normal metal nano-rings

A general scheme is developed to deal with 1D lattice systems that could be topologically complicated. It is aimed to give a complete study of two coupled normal metal rings. Our method starts with an investigation of the local expressions of the eigenfunctions. By connecting different parts of the system, all the eigenvalues and eigenfunctions can be obtained. It is found that there is a possibility for the existence of localized states, which is beyond previous expectations.