cssi/SciSciGPT-SciSciNet huggingface dataset:
Laminations and groups of homeomorphisms of the circle

If M is an atoroidal 3-manifold with a taut foliation, Thurston showed that π1(M) acts on a circle. Here, we show that some other classes of essential laminations also give rise to actions on circles. In particular, we show this for tight essential laminations with solid torus guts. We also show that pseudo-Anosov flows induce actions on circles. In all cases, these actions can be made into faithful ones, so π1(M) is isomorphic to a subgroup of Homeo(S 1). In addition, we show that the fundamental group of the Weeks manifold has no faithful action on S 1. As a corollary, the Weeks manifold does not admit a tight essential lamination with solid torus guts, a pseudo-Anosov flow, or a taut foliation. Finally, we give a proof of Thurston’s universal circle theorem for taut foliations based on a new, purely topological, proof of the Leaf Pocket Theorem.
MgII absorption through intermediate redshift galaxies

The current status and remaining questions of Mgii absorbers are reviewed with an eye toward new results incorporating high quality Hubble Space Telescope images of the absorbing galaxies. In the end, we find that our current picture of extended gaseous regions around galaxies at earlier epochs is in need of some revision; Mgii absorbing “halos” appear to be patchier and their geometry less regular than previously inferred. We also find that the so-called “weak” Mgii absorbers are associated with normal galaxies over a wide range of impact parameters, suggesting that this class of absorber does not strictly select low surface brightness, dwarf galaxies, or IGM material. We emphasize the need for a complete survey of the galaxies in quasar fields, and the importance of obtaining rotation curves of confirmed absorbing galaxies.
Non-Abelian Gauge Symmetry and the Higgs Mechanism in F-Theory

Singular fiber resolution does not describe the spontaneous breaking of gauge symmetry in F-theory, as the corresponding branch of the moduli space does not exist in the theory. Accordingly, even non-abelian gauge theories have not been fully understood in global F-theory compactifications. We present a systematic discussion of using singularity deformation, which does describe the spontaneous breaking of gauge symmetry in F-theory, to study non-abelian gauge symmetry. Since this branch of the moduli space also exists in the defining M-theory compactification, it provides the only known description of gauge theory states that exists in both pictures; they are string junctions in F-theory. We discuss how global deformations give rise to local deformations, and also give examples where local deformation can be utilized even in models where a global deformation does not exist. Utilizing deformations, we study a number of new examples, including non-perturbative descriptions of SU(3) and SU(2) gauge theories on seven-branes which do not admit a weakly coupled type IIb description. It may be of phenomenological interest that these non-perturbative descriptions do not exist for higher rank SU(N) theories.
Thermal kinetic inductance detectors for millimeter-wave detection

Thermal Kinetic-Inductance Detectors (TKIDs) combine the excellent noise performance of traditional bolometers with a radio frequency multiplexing architecture that enables the large detector counts needed for the next generation of millimeter-wave instruments. In this paper, we first discuss the expected noise sources in TKIDs and derive the limits where the phonon noise contribution dominates over the other detector noise terms: generation–recombination, amplifier, and two-level system noise. Second, we characterize aluminum TKIDs in a dark environment. We present measurements of TKID resonators with quality factors of about 10 5 at 80 mK. We also discuss the bolometer thermal conductance, heat capacity, and time constants. These were measured by the use of a resistor on the thermal island to excite the bolometers. These dark aluminum TKIDs demonstrate a noise equivalent power, NEP = 2 × 10 − 17 W / Hz , with a 1 / f knee at 0.1 Hz, which provides background noise limited performance for ground-based telescopes observing at 150 GHz.
Thermal Emission in the Southwest Clump of VY CMa

We present high spatial resolution LBTI/NOMIC $9-12$ $\mu m$ images of VY CMa and its massive outflow feature, the Southwest (SW) Clump. Combined with high-resolution imaging from HST ($0.4-1$ $\mu m$) and LBT/LMIRCam ($1-5$ $\mu m$), we isolate the spectral energy distribution (SED) of the clump from the star itself. Using radiative-transfer code DUSTY, we model both the scattered light from VY CMa and the thermal emission from the dust in the clump to estimate the optical depth, mass, and temperature of the SW Clump. The SW Clump is optically thick at 8.9 $\mu m$ with a brightness temperature of $\sim$200 K. With a dust chemistry of equal parts silicates and metallic iron, as well as assumptions on grain size distribution, we estimate a dust mass of $5.4\times10^{-5}\,M_\odot$. For a gas--to--dust ratio of 100, this implies a total mass of $5.4\times10^{-3}\,M_\odot$. Compared to the typical mass-loss rate of VY CMa, the SW Clump represents an extreme, localized mass-loss event from $\lesssim300$ years ago.
Structural and magnetic phase transitions in NdCoAsO under high pressures

We have investigated structural and magnetic phase transitions under high pressures in a quaternary rare-earth transition-metal arsenide oxide NdCoAsO compound that is isostructural to the high temperature superconductor parent phase NdFeAsO. The four-probe electrical resistance measurements carried out in a designer diamond anvil cell show that the ferromagnetic Curie temperature and antiferromagnetic Neel temperature increase with an increase in pressure. High pressure x-ray diffraction studies using a synchrotron source show a structural phase transition from a tetragonal phase to a new crystallographic phase at a pressure of 23 GPa at 300 K. The NdCoAsO sample remained antiferromagnetic and non-superconducting down to 10 K and up to the highest pressure achieved in this experiment, 53 GPa. A P–T phase diagram for NdCoAsO is presented from ambient conditions to P = 53 GPa and T = 10 K.
Modeling Tracers of Young Stellar Population Age in Star-forming Galaxies

The young stellar population of a star-forming galaxy is the primary engine driving its radiative properties. As a result, the age of a galaxy's youngest generation of stars is critical for a detailed understanding of its star formation history, stellar content, and evolutionary state. Here we present predicted equivalent widths for the Hβ, Hα, and Brγ recombination lines as a function of stellar population age. The equivalent widths are produced by the latest generations of stellar evolutionary tracks and the Starburst99 stellar population synthesis code, and are the first to fully account for the combined effects of both nebular emission and continuum absorption produced by the synthetic stellar population. Our grid of model stellar populations spans six metallicities (0.001 < Z < 0.04), two treatments of star formation history (a 106 M ☉ instantaneous burst and a continuous star formation rate of 1 M ☉ yr–1), and two different treatments of initial rotation rate (v rot = 0.0v crit and 0.4v crit). We also investigate the effects of varying the initial mass function. Given constraints on galaxy metallicity, our predicted equivalent widths can be applied to observations of star-forming galaxies to approximate the age of their young stellar populations.
The inverse problem for the Dirichlet-to-Neumann map on Lorentzian manifolds

We consider the Dirichlet-to-Neumann map $\Lambda$ on a cylinder-like Lorentzian manifold related to the wave equation related to the metric $g$, a magnetic field $A$ and a potential $q$. We show that we can recover the jet of $g,A,q$ on the boundary from $\Lambda$ up to a gauge transformation in a stable way. We also show that $\Lambda$ recovers the following three invariants in a stable way: the lens relation of $g$, and the light ray transforms of $A$ and $q$. Moreover, $\Lambda$ is an FIO away from the diagonal with a canonical relation given by the lens relation. We present applications for recovery of $A$ and $q$ in a logarithmically stable way in the Minkowski case, and uniqueness with partial data.
Weak Shock Propagation with Accretion. II. Stability of Self-similar Solutions to Radial Perturbations

Coughlin et al. (2018) (Paper I) derived and analyzed a new regime of self-similarity that describes weak shocks (Mach number of order unity) in the gravitational field of a point mass. These solutions are relevant to low energy explosions, including failed supernovae. In this paper, we develop a formalism for analyzing the stability of shocks to radial perturbations, and we demonstrate that the self-similar solutions of Paper I are extremely weakly unstable to such radial perturbations. Specifically, we show that perturbations to the shock velocity and post-shock fluid quantities (the velocity, density, and pressure) grow with time as $t^{\alpha}$, where $\alpha \le 0.12$, implying that the ten-folding timescale of such perturbations is roughly ten orders of magnitude in time. We confirm these predictions by performing high-resolution, time-dependent numerical simulations. Using the same formalism, we also show that the Sedov-Taylor blastwave is trivially stable to radial perturbations provided that the self-similar, Sedov-Taylor solutions extend to the origin, and we derive simple expressions for the perturbations to the post-shock velocity, density, and pressure. Finally, we show that there is a third, self-similar solution (in addition to the the solutions in Paper I and the Sedov-Taylor solution) to the fluid equations that describes a rarefaction wave, i.e., an outward-propagating sound wave of infinitesimal amplitude. We interpret the stability of shock propagation in light of these three distinct self-similar solutions.
Manifestations of Dynamical Localization in the Disordered XXZ Spin Chain

We study disordered XXZ spin chains in the Ising phase exhibiting droplet localization, a single cluster localization property we previously proved for random XXZ spin chains. It holds in an energy interval I near the bottom of the spectrum, known as the droplet spectrum. We establish dynamical manifestations of localization in the energy window I, including non-spreading of information, zero-velocity Lieb–Robinson bounds, and general dynamical clustering. Our results do not rely on knowledge of the dynamical characteristics of the model outside the droplet spectrum. A byproduct of our analysis is that for random XXZ spin chains this droplet localization can happen only inside the droplet spectrum.
Optimal dynamic contract for spectrum reservation in mission-critical UNB-IoT systems

Spectrum reservation is emerging as one of the potential solutions to cater for the communication needs of massive number of wireless Internet of Things (IoT) devices with reliability constraints particularly in mission-critical scenarios. In most mission-critical systems, the true utility of a reservation may not be completely known ahead of time as the unforseen events might not be completely predictable. In this paper, we present a dynamic contract approach where an advance payment is made at the time of reservation based on partial information about spectrum reservation utility. Once the complete information is obtained, a rebate on the payment is made if the reservation is released. In this paper, we present a contract theoretic approach to design an incentivized mechanism that coerces the applications to reveal their true application type resulting in greater profitability of the IoT network operator. The operator offers a menu of contracts with advanced payments and rebate to the IoT applications without having knowledge about the types of applications. The decision of the applications in selecting a contract leads to a revelation of their true type to the operator which allows it to generate higher profits than a traditional spectrum auction mechanism. Under some assumptions on distribution of the utility of the applications, closed form solutions for the optimal dynamic spectrum reservation contract are provided and the sensitivity against system parameters is analyzed.
Dynamical Evolution of Globular Clusters in Hierarchical Cosmology

We test the hypothesis that metal-poor globular clusters form within disk galaxies at redshifts z > 3. We calculate the orbits of model clusters in the time-variable gravitational potential of a Milky Way-sized galaxy, using the outputs of a cosmological N-body simulation. We find that at present the orbits are isotropic in the inner 50 kpc of the Galaxy and preferentially radial at larger distances. All clusters located outside 10 kpc from the center formed in satellite galaxies, some of which are now tidally disrupted and some of which survive as dwarf galaxies. Mergers of the progenitors lead to a spheroidal spatial distribution of model clusters, although it is more extended than that of Galactic metal-poor clusters and has a somewhat shallower power-law slope of the number density profile, γ ≈ 2.7. The combination of two-body relaxation, tidal shocks, and stellar evolution drives the evolution of the cluster mass function from an initial power law to a peaked distribution, in agreement with observations. However, not all initial conditions and not all evolution scenarios are consistent with the observed mass function of the Galactic globular clusters. We find that our best-fitting models require the average cluster density, M/R3h, to be constant initially for clusters of all mass and to remain constant with time. However, these models do not explain the observed decrease of the mean density with galactocentric distance. Both synchronous formation of all clusters at a single epoch (z = 4) and continuous formation over a span of 1.6 Gyr (between z = 9 and 3) are consistent with the data. For both formation scenarios, we provide online catalogs of the main physical properties of model clusters.
BILEPTONS – STATUS AND PROSPECTS

Theoretical background for bileptonic gauge bosons is reviewed, both the SU(15) GUT model and the 3-3-1 model. Then the mass limits for bileptons are discussed coming from e+e- scattering, polarized muon decay and muonium-antimuonium conversion. A consequence of precision electroweak data on the masses is mentioned. Discovery in e-e- at a linear collider is emphasised.
A rational framework for dynamic homogenization at finite wavelengths and frequencies

In this study, we establish an inclusive paradigm for the homogenization of scalar wave motion in periodic media (including the source term) at finite frequencies and wavenumbers spanning the first...
Quarkonium production in high energy proton-nucleus collisions: CGC meets NRQCD

We study the production of heavy quarkonium states in high energy proton-nucleus collisions. Following earlier work of Blaizot, Fujii, Gelis, and Venugopalan, we systematically include both small x evolution and multiple scattering effects on heavy quark pair production within the Color Glass Condensate (CGC) framework. We obtain for the first time expressions in the Non-Relativistic QCD (NRQCD) factorization formalism for heavy quarkonium differential cross sections as a function of transverse momentum and rapidity. We observe that the production of color singlet heavy quark pairs is sensitive to both “quadrupole” and “dipole” Wilson line correlators, whose energy evolution is described by the Balitsky-JIMWLK equations. In contrast, the color octet channel is sensitive to dipole correlators alone. In a quasi-classical approximation, our results for the color singlet channel reduce to those of Dominguez et al. [1]. We compare our results to those obtained combining the CGC with the color evaporation model and point to qualitative differences in the two approaches.
Commensurators of solvable S-arithmetic groups

We show that the abstract commensurator of an S-arithmetic subgroup of a solvable algebraic group over Q is isomorphic to the Q-points of an algebraic group, and compare this with examples of nonlinear abstract commensurators of S-arithmetic groups in positive characteristic. In particular, we include a description of the abstract commensurator of the lamplighter group .Z=2Z/oZ.
Life Outside the Golden Window: Statistical Angles on the Signal-to-Noise Problem

Lattice QCD simulations of multi-baryon correlation functions can predict the structure and reactions of nuclei without encountering the baryon chemical potential sign problem. However, they suffer from a signal-to-noise problem where Monte Carlo estimates of observables have quantum fluctuations that are exponentially larger than their average values. Recent lattice QCD results demonstrate that the complex phase of baryon correlations functions relates the baryon signal-to-noise problem to a sign problem and exhibits unexpected statistical behavior resembling a heavy-tailed random walk on the unit circle. Estimators based on differences of correlation function phases evaluated at different Euclidean times are discussed that avoid the usual signal-to-noise problem, instead facing a signal-to-noise problem as the time interval associated with the phase difference is increased, and allow hadronic observables to be determined from arbitrarily large-time correlation functions.
Cold Dark Matter Substructure and Galactic Disks

We perform a set of high-resolution, fully self-consistent dissipationless N-body simulations to investigate the influence of cold dark matter (CDM) substructure on the dynamical evolution of thin galactic disks. Our method combines cosmological simulations of galaxy-sized CDM halos to derive the properties of substructure populations and controlled numerical experiments of consecutive subhalo impacts onto initially-thin, fully-formed disk galaxies. We demonstrate that close encounters between massive subhalos and galactic disks since z ∼ 1 should be common occurrences inCDM models. In contrast, extremely few satellites in present-day CDM halos are likely to have a significant impact on the disk structure. One typical host halo merger history is used to seed controlled N-body experiments of subhalo-disk encounters. As a result of these accretion events, the disk thickens considerably at all radii with the disk scale height increasing in excess of a factor of 2 in the solar neighborhood. We show that interactions with the subhalo population produce a wealth of distinctive morphological signatures in the disk stars, many of which resemble those being discovered in the Milky Way (MW), M31, and in other disk galaxies, including: conspicuous flares; bars; low-lived, ring-like features in the outskirts; and low-density, filamentary structures above the disk plane. We compare a resulting dynamically-cold, ring-like feature in our simulations to the Monoceros ring stellar structure in the MW. The comparison shows quantitative agreement in both spatial distribution and kinematics, suggesting that such observed complex stellar components may arise naturally as disk stars are excited by encounters with subhalos. These findings highlight the significant role of CDM substructure in setting the structure of disk galaxies and driving galaxy evolution.
Two-band model for magnetism and superconductivity in nickelates

The authors suggest that after doping, the intra-orbital spin-singlet and inter-orbital spin-triplet double-hole (doublon) configurations of Ni${}^{2+}$ are competing, and they construct a two-band Hubbard model by including both the $3{d}_{{x}^{2}\ensuremath{-}{y}^{2}}$ and $3{d}_{x\phantom{\rule{0}{0ex}}y}$-orbitals. These findings show the effective exchange interactions between spin-1/2 single-holes, spin-1 (triplet) doublons, and singlet doublons are the glue for the superconductivity.
Computation of three-dimensional viscous flow over blunt lifting bodies at high angle of attack

Abstract : The viscous shock-layer equations for three-dimensional hypersonic flows of a perfect gas or equilibrium air over lifting bodies at high angles of attack have been developed. For the complex three-dimensional reentry vehicle geometries of interest, the resulting equations are written in a nonorthogonal, body-oriented coordinate system, and the three velocity components are defined in the nonorthogonal coordinate directions. Since the viscous shock-layer governing equations are parabolic in both the stream-wise and crossflow directions, the equations are solved by a highly efficient finite-difference scheme. The principal advantages of this technique are the numerical method can be used to predict the flowfield about arbitrary geometries in both subsonic and supersonic regions, the solution is direct, and the effects of inviscid-viscous interactions are uniformly valid throughout the shock layer. Numerical solutions have been obtained for a 1:1.4 (perfect gas), 1:2 ellipsoid in a perfect gas or equilibrium air and the nose portion of the shuttle orbiter at zero, 10 and 25-deg angles of attack. Comparisons were made with inviscid solutions and existing experimental data, and the agreement is good for all the cases. (Author)
Nonlinear Model Order Reduction via Lifting Transformations and Proper Orthogonal Decomposition

This paper presents a structure-exploiting nonlinear model reduction method for systems with general nonlinearities. First, the nonlinear model is lifted to a model with more structure via variable...
Loose Ends for the Exomoon Candidate Host Kepler-1625b

The claim of an exomoon candidate in the Kepler-1625b system has generated substantial discussion regarding possible alternative explanations for the purported signal. In this work we examine in detail these possibilities. First, the effect of more flexible trend models is explored and we show that sufficiently flexible models are capable of attenuating the signal, although this is an expected byproduct of invoking such models. We also explore trend models using X and Y centroid positions and show that there is no data-driven impetus to adopt such models over temporal ones. We quantify the probability that the 500 ppm moon-like dip could be caused by a Neptune-sized transiting planet to be < 0.75%. We show that neither autocorrelation, Gaussian processes nor a Lomb-Scargle periodogram are able to recover a stellar rotation period, demonstrating that K1625 is a quiet star with periodic behavior < 200 ppm. Through injection and recovery tests, we find that the star does not exhibit a tendency to introduce false-positive dip-like features above that of pure Gaussian noise. Finally, we address a recent re-analysis by Kreidberg et al (2019) and show that the difference in conclusions is not from differing systematics models but rather the reduction itself. We show that their reduction exhibits i) slightly higher intra-orbit and post-fit residual scatter, ii) $\simeq$ 900 ppm larger flux offset at the visit change, iii) $\simeq$ 2 times larger Y-centroid variations, and iv) $\simeq$ 3.5 times stronger flux-centroid correlation coefficient than the original analysis. These points could be explained by larger systematics in their reduction, potentially impacting their conclusions.
A note on the abelianizations of finite-index subgroups of the mapping class group

For some g ≥ 3, let Γ be a finite index subgroup of the mapping class group of a genus g surface (possibly with boundary components and punctures). An old conjecture of Ivanov says that the abelianization of Γ should be finite. In the paper we prove two theorems supporting this conjecture. For the first, let T x denote the Dehn twist about a simple closed curve x. For some n > 1, we have T n x ∈ Γ. We prove that T n x is torsion in the abelianization of Γ. Our second result shows that the abelianization of Γ is finite if Γ contains a "large chunk" (in a certain technical sense) of the Johnson kernel, that is, the subgroup of the mapping class group generated by twists about separating curves.
Dynamics of quantum information

The ability to harness the dynamics of quantum information and entanglement is necessary for the development of quantum technologies and the study of complex quantum systems. On the theoretical side, the dynamics of quantum information is a topic that is helping us to unify and confront common problems in otherwise disparate fields in physics, such as quantum statistical mechanics and cosmology. On the experimental side, impressive developments in the manipulation of neutral atoms and trapped ions are providing new ways to probe their quantum dynamics. Here, we overview and discuss progress in characterizing and understanding the dynamics of quantum entanglement and information scrambling in quantum many-body systems. The level of control attainable over both the internal and external degrees of freedom of individual particles in these systems provides insight into the intrinsic connection between entanglement and thermodynamics, and between bounds on information transport and computational complexity of interacting systems. In turn, this understanding should enable the realization of quantum technologies. The dynamics of quantum information is opening new perspectives on the behaviour of complex many-body systems. This Perspective covers progress made with atomic gases and trapped ions for accessing the dynamics of quantum correlations, entanglement and information scrambling in a broad parameter regime.
P-type zinc oxide spinels: application to transparent conductors and spintronics

We report on the electronic and optical properties of two theoretically predicted stable spinel compounds of the form ZnBO, where B = Ni or Cu; neither compound has been previously synthesized, so we compare them to the previously studied p-type ZnCoO spinel. These new materials exhibit spin polarization, which is useful for spintronics applications, and broad conductivity maxima near the valence band edge that indicate good p-type dopability. We show that electrons on the octahedrally coordinated Zn atom fall deep within the valence band and do not contribute significantly to the electronic structure near the band edge of the material, while the O and tetrahedrally coordinated B electrons hybridize broadly in the shallow valence states, resulting in increasing curvature (i.e., decreased electron effective mass) of valence bands near the band edge. In particular, ZnCuO exhibits high electrical conductivities in the p-doping region near the valence band edge that, at , are twice the maximum found for ZnCoO , a previously synthesized compound in this class of materials. This material also exhibits ferromagnetism in all of its most stable structures, which makes it a good candidate for further study as a dilute magnetic semiconductor.
Functional generative design: an evolutionary approach to 3D-printing

Consumer-grade printers are widely available, but their ability to print complex objects is limited. Therefore, new designs need to be discovered that serve the same function, but are printable. A representative such problem is to produce a working, reliable mechanical spring. The proposed methodology for discovering solutions to this problem consists of three components: First, an effective search space is learned through a variational autoencoder (VAE); second, a surrogate model for functional designs is built; and third, a genetic algorithm is used to simultaneously update the hyperparameters of the surrogate and to optimize the designs using the updated surrogate. Using a car-launcher mechanism as a test domain, spring designs were 3D-printed and evaluated to update the surrogate model. Two experiments were then performed: First, the initial set of designs for the surrogate-based optimizer was selected randomly from the training set that was used for training the VAE model, which resulted in an exploitative search behavior. On the other hand, in the second experiment, the initial set was composed of more uniformly selected designs from the same training set and a more explorative search behavior was observed. Both of the experiments showed that the methodology generates interesting, successful, and reliable spring geometries robust to the noise inherent in the 3D printing process. The methodology can be generalized to other functional design problems, thus making consumer-grade 3D printing more versatile.
Active control of probability amplitudes in a mesoscale system via feedback-induced suppression of dissipation and noise

We demonstrate that a three-terminal potentiostat circuit reduces the coupling between an electronic excitation transfer (EET) system and its environment, by applying a low-noise voltage to its electrical terminals. Inter-state interference is preserved in the EET system by attenuating the dissipation in the quantum system arising from coupling to the surrounding thermodynamic bath. A classical equivalent circuit is introduced to model the environment-coupled excitation transfer for a simplified, two-state system. This model provides a qualitative insight into how the electronic feedback affects the transition probabilities and selectively reduces dissipative coupling for one of the participant energy levels EET system. Furthermore, we show that the negative feedback also constrains r.m.s. fluctuations of the energy of environmental vibrational states, resulting in persistent spectral coherence between the decoupled state and vibronic levels of the complementary state. The decoupled vibronic channel there...
An Adaptive Local Discrete Convolution Method for the Numerical Solution of Maxwell's Equations

Author(s): Lo, Boris | Advisor(s): Colella, Phillip | Abstract: A high order multilevel numerical solver for Maxwell's equations using local discrete convolutions is presented. Maxwell's equations are embedded in a system of wave equations. The solution to this system can be derived with the method of spherical means. When the source terms are prescribed functions then there is an explicit update formula using the propagator form of the solution and Duhamel's formula. And when the source terms are dependent on the fields, the propagator can be embedded in the system of differential equations by a change of variables by Lawson's method. The spherical means operations are discretized using the framework from Tornberg and on uniform spacing rectangular grids the procedure becomes constant coefficient stencil operations. While the source term integration is handled with a quadrature scheme or a time integrator. This method can be parallelized with standard domain decomposition. Since this method places the electric and magnetic fields on the same grids, as opposed to staggered grids used in standard grid based solvers for Maxwell's equations, and that it has no time stepping restriction, because it is a propagator based method, it can be extended to use local mesh refinement with only simple interpolating and sampling operators.
Efficient Geometric Probabilities of Multi-Transiting Exoplanetary Systems from CORBITS

NASA's Kepler Space Telescope has successfully discovered thousands of exoplanet candidates using the transit method, including hundreds of stars with multiple transiting planets. In order to estimate the frequency of these valuable systems, it is essential to account for the unique geometric probabilities of detecting multiple transiting extrasolar planets around the same parent star. In order to improve on previous studies that used numerical methods, we have constructed an efficient, semi-analytical algorithm called CORBITS which, given a collection of conjectured exoplanets orbiting a star, computes the probability that any particular group of exoplanets can be observed to transit. The algorithm applies theorems of elementary differential geometry to compute the areas bounded by circular curves on the surface of a sphere (see Ragozzine & Holman 2010). The implemented algorithm is more accurate and orders of magnitude faster than previous algorithms, based on comparisons with Monte Carlo simulations. We use CORBITS to show that the present solar system would only show a maximum of 3 transiting planets, but that this varies over time due to dynamical evolution. We also used CORBITS to geometrically debias the period ratio and mutual Hill sphere distributions of Kepler's multi-transiting planet candidates, which results in shifting these distributions towards slightly larger values. In an Appendix, we present additional semi-analytical methods for determining the frequency of exoplanet mutual events, i.e., the geometric probability that two planets will transit each other (Planet-Planet Occultation, relevant to transiting circumbinary planets) and the probability that this transit occurs simultaneously as they transit their star. The CORBITS algorithms and several worked examples are publicly available at this https URL
The Completed Finite Period Map and Galois Theory of Supercongruences

A period is a complex number arising as the integral of a rational function with algebraic number coefficients over a rationally-defined region. Although periods are typically transcendental numbers, there is a conjectural Galois theory of periods coming from the theory of motives. This paper formalizes an analogy between a class of periods called multiple zeta values, and congruences for rational numbers modulo prime powers (called supercongruences). We construct an analogue of the motivic period map in the setting of supercongruences, and use it to define a Galois theory of supercongruences. We describe an algorithm using our period map to find and prove supercongruences, and we provide software implementing the algorithm.
AN ALTERNATIVE PERSPECTIVE ON PROJECTIVITY OF MODULES

We approach the analysis of the extent of the projectivity of modules from a fresh perspective as we introduce the notion of relative subprojectivity. A module M is said to be N-subprojective if for every epimorphism g : B → N and homomorphism f : M → N, there exists a homomorphism h : M → B such that gh = f. For a module M, the subprojectivity domain of M is defined to be the collection of all modules N such that M is N-subprojective. We consider, for every ring R, the subprojective profile of R, namely, the class of all subprojectivity domains for R modules. We show that the subprojective profile of R is a semi-lattice, and consider when this structure has coatoms or a smallest element. Modules whose subprojectivity domain is as smallest as possible will be called subprojectively poor (sp-poor) or projectively indigent (p-indigent), and those with co-atomic subprojectivy domain are said to be maximally subprojective. While we do not know if sp-poor modules and maximally subprojective modules exist over every ring, their existence is determined for various families. For example, we determine that artinian serial rings have sp-poor modules and attain the existence of maximally subprojective modules over the integers and for arbitrary V-rings. This work is a natural continuation to recent papers that have embraced the systematic study of the injective, projective and subinjective profiles of rings.
Atomic swelling upon compression

The hydrogen atom under the pressure of a spherical penetrable confinement potential of a decreasing radius r0 is explored, as a case study. A counter-intuitive effect of atomic swelling, rather than shrinking, with decreasing r0 is unraveled when r0 reaches, and remains smaller than, a certain critical value. Upon swelling, the size of the atom is shown to increase by an order of magnitude, or more, compared to the size of the free atom. Changes of photoabsorption properties of the hydrogen atom under said confinement are uncovered and demonstrated.
Projections in the curve complex arising from covering maps

Let $P : \Sigma \rightarrow S$ be a finite degree covering map between surfaces. Rafi and Schleimer show that there is an induced quasi-isometric embedding $\Pi : \mathcal{C}(S) \rightarrow \mathcal{C}(\Sigma)$ between the associated curve complexes. We define an operation on curves in $\mathcal{C}(\Sigma)$ using minimal intersection number conditions and prove that it approximates a nearest point projection to $\Pi(\mathcal{C}(S))$. We also approximate hulls of finite sets of vertices in the curve complex, together with their corresponding nearest point projections, using intersection numbers.
Adiabatic limits and Kazdan–Warner equations

We study the limiting behaviour of solutions to abelian vortex equations when the volume of the underlying Riemann surface grows to infinity. We prove that the solutions converge smoothly away from finitely many points. The proof relies on a priori estimates for functions satisfying generalised Kazdan–Warner equations. We relate our results to the work of Hong, Jost, and Struwe on classical vortices, and that of Haydys and Walpuski on the Seiberg–Witten equations with multiple spinors.
Totally geodesic surfaces with arbitrarily many compressions

Let M be a compact, connected, irreducible, orientable 3–manifold with torus boundary @M . A slope on @M is an isotopy class of simple closed curves on @M . We use . ; ˇ/ to denote the absolute value of the algebraic intersection number between the slopes and ˇ . Culler, Gordon, Luecke and Shalen [4] showed that if F is a closed, orientable, embedded, incompressible surface in M with no incompressible annulus joining F and @M , and F compresses in the Dehn fillings M. / and M.ˇ/, then . ; ˇ/ 2. In [17], Wu improved this to . ; ˇ/ 1, and hence F remains incompressible in M. / for all but at most three slopes .
A technique of direct tension measurement of a strung fine wire

Abstract We present a new technique of direct measurement of wire tensions in wire chambers. A specially designed circuit plucks the wire using the Lorentz force and measures the frequency of damped transverse oscillations of the wire. The technique avoids the usual time-consuming necessity of tuning circuit parameter to a resonance. It allows a fast and convenient determination of tensions and is straightforward to implement.
Dense Regions in Supersonic Isothermal Turbulence

The properties of supersonic isothermal turbulence influence a variety of astrophysical phenomena, including the structure and evolution of star-forming clouds. This work presents a simple model for the structure of dense regions in turbulence in which the density distribution behind isothermal shocks originates from rough hydrostatic balance between the pressure gradient behind the shock and its deceleration from ram pressure applied by the background fluid. Using simulations of supersonic isothermal turbulence and idealized waves moving through a background medium, we show that the structural properties of dense, shocked regions broadly agree with our analytical model. Our work provides a new conceptual picture for describing the dense regions, which complements theoretical efforts to understand the bulk statistical properties of turbulence and attempts to model the more complex features of star-forming clouds like magnetic fields, self-gravity, or radiative properties.
Blue Supergiant X-Ray Binaries in the Nearby Dwarf Galaxy IC 10

In young starburst galaxies, the X-ray population is expected to be dominated by the relics of the most massive and short-lived stars, black-hole and neutron-star high mass X-ray binaries (XRBs). In the closest such galaxy, IC 10, we have made a multi-wavelength census of these objects. Employing a novel statistical correlation technique, we have matched our list of 110 X-ray point sources, derived from a decade of Chandra observations, against published photometric data. We report an 8 sigma correlation between the celestial coordinates of the two catalogs, with 42 X-ray sources having an optical counterpart. Applying an optical color-magnitude selection to isolate blue supergiant (SG) stars in IC 10, we find 16 matches. Both cases show a statistically significant overabundance versus the expectation value for chance alignments. The blue objects also exhibit systematically higher fx/fv ratios than other stars in the same magnitude range. Blue SG-XRBs include a major class of progenitors of double-degenerate binaries, hence their numbers are an important factor in modeling the rate of gravitational wave sources. We suggest that the anomalous features of the IC 10 stellar population are explained if the age of the IC 10 starburst is close to the time of the peak of interaction for massive binaries.
Long-time persistence of hydrodynamic memory boosts microparticle transport

At short times, microparticle motion couples with the ambient fluid, which can transiently store and return kinetic energy. Here, numerical experiments reveal that this hydrodynamic memory effect hedges against space- and time-varying forces. As a result, hydrodynamic memory can boost the transport efficiency of driven microparticles beyond what is expected from standard Langevin theory.
Lithium niobate photonic-crystal electro-optic modulator

Modern advanced photonic integrated circuits require dense integration of high-speed electro-optic functional elements on a compact chip that consumes only moderate power. Energy efficiency, operation speed, and device dimension are thus crucial metrics underlying almost all current developments of photonic signal processing units. Recently, thin-film lithium niobate (LN) emerges as a promising platform for photonic integrated circuits. Here, we make an important step towards miniaturizing functional components on this platform, reporting high-speed LN electro-optic modulators, based upon photonic crystal nanobeam resonators. The devices exhibit a significant tuning efficiency up to 1.98 GHz V-1, a broad modulation bandwidth of 17.5 GHz, while with a tiny electro-optic modal volume of only 0.58 μm3. The modulators enable efficient electro-optic driving of high-Q photonic cavity modes in both adiabatic and non-adiabatic regimes, and allow us to achieve electro-optic switching at 11 Gb s-1 with a bit-switching energy as low as 22 fJ. The demonstration of energy efficient and high-speed electro-optic modulation at the wavelength scale paves a crucial foundation for realizing large-scale LN photonic integrated circuits that are of immense importance for broad applications in data communication, microwave photonics, and quantum photonics.
Planck 2018 and brane inflation revisited

We revisit phenomenological as well as string-theoretical aspects of D-brane inflation cosmological models. Phenomenologically these models stand out on par with α-attractors, as models with Planck-compatible values of ns, moving down to the sweet spot in the data with decreasing value of r. On the formal side we present a new supersymmetric version of these models in the context of de Sitter supergravity with a nilpotent multiplet and volume modulus stabilization. The geometry of the nilpotent multiplet is evaluated in the framework of string theory.
PERSPECTIVES ON INTRACLUSTER ENRICHMENT AND THE STELLAR INITIAL MASS FUNCTION IN ELLIPTICAL GALAXIES

The amount of metals in the Intracluster Medium (ICM) in rich galaxy clusters exceeds that expected based on the observed stellar population by a large factor. We quantify this discrepancy--which we term the "cluster elemental abundance paradox"--and investigate the required properties of the ICM-enriching population. The necessary enhancement in metal enrichment may, in principle, originate in the observed stellar population if a larger fraction of stars in the supernova-progenitor mass range form from an initial mass function (IMF) that is either bottom-light or top-heavy, with the latter in some conflict with observed ICM abundance ratios. Other alternatives that imply more modest revisions to the IMF, mass return and remnant fractions, and primordial fraction, posit an increase in the fraction of 3-8 solar mass stars that explode as SNIa or assume that there are more stars than conventionally thought--although the latter implies a high star formation efficiency. We discuss the feasibility of these various solutions and the implications for the diversity of star formation, the process of elliptical galaxy formation, and the nature of this hidden source of ICM metal enrichment in light of recent evidence of an elliptical galaxy IMF that, because it is skewed to low masses, deepens the paradox.
Online Stochastic Optimization of Networked Distributed Energy Resources

This paper investigates distributed control and incentive mechanisms to coordinate distributed energy resources (DERs) with both continuous and discrete decision variables as well as device dynamics in distribution grids. We formulate a multiperiod social welfare maximization problem, and based on its convex relaxation propose a distributed stochastic dual gradient algorithm for managing DERs. We further extend it to an online real-time setting with time-varying operating conditions, asynchronous updates by devices, and feedback being leveraged to account for nonlinear power flows as well as reduce communication overhead. The resulting algorithm provides a general online stochastic optimization algorithm for coordinating networked DERs with discrete power setpoints and dynamics to meet operational and economic objectives and constraints. We characterize the convergence of the algorithm analytically and evaluate its performance numerically.
Asymmetric LOCO Codes: Constrained Codes for Flash Memories

In data storage and data transmission, certain patterns are more likely to be subject to error when written (transmitted) onto the media. In magnetic recording systems with binary data and bipolar non-return-to-zero signaling, patterns that have insufficient separation between consecutive transitions exacerbate inter-symbol interference. Constrained codes are used to eliminate such error-prone patterns. A recent example is a new family of capacity-achieving constrained codes, named lexicographically-ordered constrained codes (LOCO codes). LOCO codes are symmetric, that is, the set of forbidden patterns is closed under taking pattern complements. LOCO codes are suboptimal in terms of rate when used in Flash devices where block erasure is employed since the complement of an error-prone pattern is not detrimental in these devices. This paper introduces asymmetric LOCO codes (A-LOCO codes), which are lexicographically-ordered constrained codes that forbid only those patterns that are detrimental for Flash performance. A-LOCO codes are also capacity-achieving, and at finite-lengths, they offer higher rates than the available state-of-the-art constrained codes designed for the same goal. The mapping-demapping between the index and the codeword in A-LOCO codes allows low-complexity encoding and decoding algorithms that are simpler than their LOCO counterparts.
DIRECT IMAGING IN THE HABITABLE ZONE AND THE PROBLEM OF ORBITAL MOTION

High contrast imaging searches for exoplanets have been conducted on 2.4-10 m telescopes, typically at H band (1.6 μm) and used exposure times of ~1 hr to search for planets with semi-major axes of 10 AU. We are beginning to plan for surveys using extreme-AO systems on the next generation of 30 m class telescopes, where we hope to begin probing the habitable zones (HZs) of nearby stars. Here we highlight a heretofore ignorable problem in direct imaging: planets orbit their stars. Under the parameters of current surveys, orbital motion is negligible over the duration of a typical observation. However, this motion is not negligible when using large diameter telescopes to observe at relatively close stellar distances (1-10 pc), over the long exposure times (10-20 hr) necessary for direct detection of older planets in the HZ. We show that this motion will limit our achievable signal-to-noise ratio and degrade observational completeness. Even on current 8 m class telescopes, orbital motion will need to be accounted for in an attempt to detect HZ planets around the nearest Sun-like stars α Cen A&B, a binary system now known to harbor at least one planet. Here we derive some basic tools for analyzing this problem, and ultimately show that the prospects are good for de-orbiting a series of shorter exposures to correct for orbital motion.
A Hidden Markov Tree Model for Flood Extent Mapping in Heavily Vegetated Areas based on High Resolution Aerial Imagery and DEM: A Case Study on Hurricane Matthew Floods

Flood extent mapping plays a crucial role in disaster management and national water forecasting. In recent years, high-resolution optical imagery becomes increasingly available with the deployment ...