cssi/SciSciGPT-SciSciNet huggingface dataset:
SYM correlators and the maldacena conjecture

Abstract We report on progress in evaluating quantum filed theories with supersymmetric discrete light-cone quantization (SDLCQ). We compare the method to lattice gauge theory and point out its relevance for lattice calculations. As an exciting application we present a test of the Maldacena conjecture. We test the conjecture by evaluating the correlator of the stress-energy tensor in the strong coupling field theory and comparing to the string theory prediction of its behavior as a function of the distance. Our numerical results support the Maldacena conjecture and are within 10–15% of the predicted results.
$p$-adic Hodge theory in rigid analytic families

We study the functors DB∗(V ), where B∗ is one of Fontaine’s period rings and V is a family of Galois representations with coefficients in an affinoid algebra A. We first relate them to (φ,Γ)-modules, showing that DHT(V ) = ⊕ i∈Z(DSen(V ) ⋅ ti)ΓK, DdR(V ) = Ddif(V )ΓK, and Dcris(V ) = Drig(V )[1∕t]ΓK; this generalizes results of Sen, Fontaine, and Berger. We then deduce that the modules DHT(V ) and DdR(V ) are coherent sheaves on Sp(A), and Sp(A) is stratified by the ranks of submodules DHT[a,b](V ) and DdR[a,b](V ) of “periods with Hodge–Tate weights in the interval [a,b]@”. Finally, we construct functorial B∗-admissible loci in Sp(A), generalizing a result of Berger and Colmez to the case where A is not necessarily reduced.
Maxwell's equations in Minkowski's world: their premetric generalization and the electromagnetic energy‐momentum tensor

In December 1907, Minkowski expressed the Maxwell equations in the very beautiful and compact 4-dimensional form: lor f = -s, lor F*= 0. Here ‘lor’, an abbreviation of Lorentz, represents the 4-dimensional differential operator. We study Minkowski's derivation and show how these equations generalize to their modern premetric form in the framework of tensor and exterior calculus (valid also in general relativity). After mentioning some applications of premetric electrodynamics, we turn to Minkowski's discovery of the energy-momentum tensor of the electromagnetic field. We discuss how he arrived at it and how its premetric formulation looks like.
Performance of several solid state photomultipliers with CLYC scintillator

Cs 2 LiYCl 6 :Ce3+ (CLYC) is an inorganic scintillator that has recently garnered attention for its ability to detect and discriminate between gammas and thermal neutrons. We investigate several important performance parameters of three different solid state photomultipliers (SSPMs) when reading out CLYC crystals: linearity, energy resolution, and pulse shape and discrimination ability. These performance parameters are assessed at a variety of temperatures between −20°C and +50°C.
Why does the effective field theory of inflation work

The effective field theory (EFT) of inflation has become the preferred method for computing cosmological correlation functions of the curvature fluctuation, ζ. It makes explicit use of the soft breaking of time diffeomorphisms by the inflationary background to organize the operators expansion in the action of the Goldstone mode π associated with this breaking. Despite its ascendancy, there is another method for calculating ζ correlators, involving the direct calculation of the so-called Horndeski action order by order in powers of ζ and its derivatives. The question we address in this work is whether or not the ζ correlators calculated in these seemingly different ways are in fact the same. The answer is that the actions to cubic order in either set of variables do indeed give rise to the same ζ bispectra, but that to make this equivalence manifest requires a careful understanding of the non-linear transformations relating π to ζ and how boundary terms in the actions are affected by imposing this relation. As a by product of our study we find that the calculations in the π language can be simplified considerably in a way that allows us to use only the linear part of the π−ζ relation simply by changing the coefficients of some of the operators in the EFT. We also note that a proper accounting of the boundary terms will be of the greatest importance when computing the bispectrum for more general initial states than the Bunch-Davies one.
An optimal graph-search method for secure state estimation

Abstract The growing complexity of modern Cyber–Physical Systems (CPS) and the frequent communication between their components make them vulnerable to malicious attacks. As a result, secure state estimation is a critical requirement for the control of these systems. Many existing secure state estimation methods suffer from combinatorial complexity which grows with the number of states and sensors in the system. This complexity can be mitigated using optimization-based methods that relax the original state estimation problem, although at the cost of optimality as these methods often identify attack-free sensors as attacked. In this paper, we propose a new optimal graph-search algorithm to correctly identify malicious attacks and to securely estimate the states even in large-scale CPS modeled as linear time-invariant systems The graph consists of layers, each one containing two nodes capturing a truth assignment of any given sensor, and directed edges connecting adjacent layers only. Then, our algorithm searches the layers of this graph incrementally, favoring directions at higher layers with more attack-free assignments, while actively managing a repository of nodes to be expanded at later iterations. The proposed search bias and the ability to revisit nodes in the repository and self-correct, allow our graph-search algorithm to reach the optimal assignment faster and tackle larger problems. We show that our algorithm is complete and optimal provided that process and measurement noises do not dominate the attack signal. Moreover, we provide numerical simulations that demonstrate the ability of our algorithm to correctly identify attacked sensors and securely reconstruct the state. Our simulations show that our method outperforms existing algorithms both in terms of optimality and execution time.
Cavity piezooptomechanics: Piezoelectrically excited, optically transduced optomechanical resonators

We present a monolithic integrated aluminum nitride (AlN) optomechanical resonator in which the mechanical motion is actuated by piezoelectric force and the displacement is transduced by a high-Q optical cavity. The AlN optomechanical resonator is excited from a radio-frequency electrode via a small air gap to eliminate resonator-to-electrode loss. We observe the electrically excited mechanical motion at 47.3 MHz, 1.04 GHz, and 3.12 GHz, corresponding to the 1st, 2nd, and 4th radial-contour mode of the wheel resonator, respectively. An equivalent circuit model is developed to describe the observed Fano-like resonance spectrum.
Isometric Immersions and Compensated Compactness

A fundamental problem in differential geometry is to characterize intrinsic metrics on a two-dimensional Riemannian manifold \({{\mathcal M}^2}\) which can be realized as isometric immersions into \({\mathbb{R}^3}\). This problem can be formulated as initial and/or boundary value problems for a system of nonlinear partial differential equations of mixed elliptic-hyperbolic type whose mathematical theory is largely incomplete. In this paper, we develop a general approach, which combines a fluid dynamic formulation of balance laws for the Gauss-Codazzi system with a compensated compactness framework, to deal with the initial and/or boundary value problems for isometric immersions in \({\mathbb{R}^3}\). The compensated compactness framework formed here is a natural formulation to ensure the weak continuity of the Gauss-Codazzi system for approximate solutions, which yields the isometric realization of two-dimensional surfaces in \({\mathbb{R}^3}\).
A CONSISTENT ORBITAL STABILITY ANALYSIS FOR THE GJ 581 SYSTEM

We apply a combination of N-body modeling techniques and automated data fitting with Monte Carlo Markov Chain uncertainty analysis of Keplerian orbital models to RV data to determine long-term stability of the planetary system GJ 581. We find that while there are stability concerns with the four-planet model as published by Forveille et al., when uncertainties in the system are accounted for, particularly stellar jitter, the hypothesis that the four-planet model is gravitationally unstable is not statistically significant. Additionally, the system including proposed planet g by Vogt et al. also shows some stability concerns when eccentricities are allowed to float in the orbital fit, yet when uncertainties are included in the analysis, the system including planet g also cannot be proven to be unstable. We present revised reduced χ{sup 2} values for Keplerian astrocentric orbital fits assuming four-planet and five-planet models for GJ 581 under the condition that best fits must be stable, and we find no distinguishable difference by including planet g in the model. Additionally, we present revised orbital element estimates for each, assuming uncertainties due to stellar jitter under the constraint of the system being gravitationally stable.
Baryon Number Nonconservation and the Stability of Strange Matter

If baryon number nonconservation exists in the form of an effective six-quark operator which also changes strangeness by four units, it could have a tremendous impact on the absolute stability of strange quark matter. We show that such an operator is negligible in the supersymmetric standard model with $\lambda_{ijk} u_i^c d_j^c d_k^c$ terms in the superpotential, but may be of importance in models with exotic particle content. From the experimental lower limit of 1025 years on the stability of nuclei, we find a model-independent lower limit of the order 105 years on the stability of strange matter against such decays.
QUANTUM TEICHMÜLLER THEORY AND REPRESENTATIONS OF THE PURE BRAID GROUP

We adapt some of the methods of quantum Teichmuller theory to construct a family of representations of the pure braid group of the sphere.
Blockout: Dynamic Model Selection for Hierarchical Deep Networks

Most deep architectures for image classification–even those that are trained to classify a large number of diverse categories–learn shared image representations with a single model. Intuitively, however, categories that are more similar should share more information than those that are very different. While hierarchical deep networks address this problem by learning separate features for subsets of related categories, current implementations require simplified models using fixed architectures specified via heuristic clustering methods. Instead, we propose Blockout, a method for regularization and model selection that simultaneously learns both the model architecture and parameters. A generalization of Dropout, our approach gives a novel parametrization of hierarchical architectures that allows for structure learning via back-propagation. To demonstrate its utility, we evaluate Blockout on the CIFAR and Image Net datasets, demonstrating improved classification accuracy, better regularization performance, faster training, and the clear emergence of hierarchical network structures.
DWARF GALAXY FORMATION WITH H2-REGULATED STAR FORMATION. II. GAS-RICH DARK GALAXIES AT REDSHIFT 2.5

We present a cosmological hydrodynamic simulation of the formation of dwarf galaxies at redshifts z 2.5 using a physically motivated model for H2-regulated star formation. Our simulation, performed using the Enzo code and reaching a peak resolution of 109 proper parsecs at z = 2.5, extends the results of Kuhlen et al. to significantly lower redshifts. We show that a star formation prescription regulated by the local H2 abundance leads to the suppression of star formation in dwarf galaxy halos with M h 1010 M ☉ and to a large population of gas-rich "dark galaxies" at z = 2.5 with low star formation efficiencies and gas depletion timescales >20 Gyr. The fraction of dark galaxies is 60% at M h 1010 M ☉ and increases rapidly with decreasing halo mass. Dark galaxies form late and their gaseous disks never reach the surface densities, 5700 M ☉ pc–2 (Z/10–3 Z ☉)–0.88, that are required to build a substantial molecular fraction. Despite this large population of dark galaxies, we show that our H2-regulated simulation is consistent with both the observed luminosity function of galaxies and the cosmological mass density of neutral gas at z 2.5. Moreover, our results provide a theoretical explanation for the recent detection in fluorescent Lyα emission of gaseous systems at high redshift with little or no associated star formation. We further propose that H2-regulation may offer a fresh solution to a number of outstanding "dwarf galaxy problems" in ΛCDM. In particular, H2-regulation leads galaxy formation to become effectively stochastic on mass scales of M h ~ 1010 M ☉, and thus these massive dwarfs are not "too big to fail."
Stochastic Enumeration with Importance Sampling

Many hard problems in the computational sciences are equivalent to counting the leaves of a decision tree, or, more generally, by summing a cost function over the nodes. These problems include calculating the permanent of a matrix, finding the volume of a convex polyhedron, and counting the number of linear extensions of a partially ordered set. Many approximation algorithms exist to estimate such sums. One of the most recent is Stochastic Enumeration (SE), introduced in 2013 by Rubinstein. In 2015, Vaisman and Kroese provided a rigorous analysis of the variance of SE, and showed that SE can be extended to a fully polynomial randomized approximation scheme for certain cost functions on random trees. We present an algorithm that incorporates an importance function into SE, and provide theoretical analysis of its efficacy. We also present the results of numerical experiments to measure the variance of an application of the algorithm to the problem of counting linear extensions of a poset, and show that introducing importance sampling results in a significant reduction of variance as compared to the original version of SE.
Domain walls in strontium titanate

Density functional theory calculations of twin-domain walls in strontium titanate are presented. The two possible domain walls are characterized. The domain wall type is set by the relative phase of the octahedral rotations in the body-centered-tetragonal SrTiO3 on either side of the domain wall. The width of the domain walls is estimated to be approximately 3 nm.
Experimental Passive-State Preparation for Continuous-Variable Quantum Communications

In the Gaussian-modulated coherent state quantum key distribution (QKD) protocol, the sender first generates Gaussian-distributed random numbers and then encodes them on weak laser pulses actively by performing amplitude and phase modulations. Recently, an equivalent passive QKD scheme has been proposed by exploring the intrinsic field fluctuations of a thermal source [B. Qi, P. G. Evans, and W. P. Grice, Phys. Rev. A 97, 012317 (2018)]. This passive QKD scheme is especially appealing for chip-scale implementation since no active modulation is required. In this paper, we conduct an experimental study of the passively encoded QKD scheme using an off-the-shelf amplified spontaneous emission source operated in continuous-wave mode. Our results show that the excess noise introduced by the passive state preparation scheme can be effectively suppressed by applying optical attenuation and a secure key can be generated over metro-area distances.
CLAR: A Cross-Lingual Argument Regularizer for Semantic Role Labeling.

Semantic role labeling (SRL) identifies predicate-argument structure(s) in a given sentence. Although different languages have different argument annotations, polyglot training, the idea of training one model on multiple languages, has previously been shown to outperform monolingual baselines, especially for low resource languages. In fact, even a simple combination of data has been shown to be effective with polyglot training by representing the distant vocabularies in a shared representation space. Meanwhile, despite the dissimilarity in argument annotations between languages, certain argument labels do share common semantic meaning across languages (e.g. adjuncts have more or less similar semantic meaning across languages). To leverage such similarity in annotation space across languages, we propose a method called Cross-Lingual Argument Regularizer (CLAR). CLAR identifies such linguistic annotation similarity across languages and exploits this information to map the target language arguments using a transformation of the space on which source language arguments lie. By doing so, our experimental results show that CLAR consistently improves SRL performance on multiple languages over monolingual and polyglot baselines for low resource languages.
Evaluation of Implicit‐Explicit Additive Runge‐Kutta Integrators for the HOMME‐NH Dynamical Core

The nonhydrostatic High Order Method Modeling Environment (HOMME-NH) atmospheric dynamical core supports acoustic waves that propagate significantly faster than the advective wind speed, thus greatly limiting the timestep size that can be used with standard explicit time-integration methods. Resolving acoustic waves is unnecessary for accurate climate and weather prediction. This numerical stiffness is addressed herein by considering implicit-explicit additive Runge-Kutta (ARK IMEX) methods that can treat the acoustic waves in a stable manner without requiring implicit treatment of non-stiff modes. Various ARK IMEX methods are evaluated for their efficiency in producing accurate solutions, ability to take large timestep sizes, and sensitivity to grid cell length ratio. Both the Gravity Wave test and Baroclinic Instability test from the 2012 Dynamical Core Model Intercomparison Project (DCMIP) are used to recommend 5 of the 27 ARK IMEX methods for use in HOMME-NH.
Mapping the Gas Turbulence in the Coma Cluster: Predictions for Astro-H

Astro-H will be able for the first time to map gas velocities and detect turbulence in galaxy clusters. One of the best targets for turbulence studies is the Coma cluster, due to its proximity, absence of a cool core, and lack of a central active galactic nucleus. To determine what constraints Astro-H will be able to place on the Coma velocity field, we construct simulated maps of the projected gas velocity and compute the second-order structure function, an analog of the velocity power spectrum. We vary the injection scale, dissipation scale, slope, and normalization of the turbulent power spectrum, and apply measurement errors and finite sampling to the velocity field. We find that even with sparse coverage of the cluster, Astro-H will be able to measure the Mach number and the injection scale of the turbulent power spectrum-the quantities determining the energy flux down the turbulent cascade and the diffusion rate for everything that is advected by the gas (metals, cosmic rays, etc.). Astro-H will not be sensitive to the dissipation scale or the slope of the power spectrum in its inertial range, unless they are outside physically motivated intervals. We give the expected confidence intervals for the injection scale and the normalization of the power spectrum for a number of possible pointing configurations, combining the structure function and velocity dispersion data. Importantly, we also determine that measurement errors on the line shift will bias the velocity structure function upward, and show how to correct this bias.
Observations of an Eruptive Solar Flare in the Extended EUV Solar Corona

We present observations of a powerful solar eruption, accompanied by an X8.2 solar flare, from NOAA Active Region 12673 on 2017 September 10 by the Solar Ultraviolet Imager (SUVI) on the GOES-16 spacecraft. SUVI is noteworthy for its relatively large field of view, which allows it to image solar phenomena to heights approaching 2 solar radii. These observations include the detection of an apparent current sheet associated with magnetic reconnection in the wake of the eruption, and evidence of an extreme-ultraviolet wave at some of the largest heights ever reported. We discuss the acceleration of the nascent coronal mass ejection to approximately 2000 km s−1 at about 1.5 solar radii. We compare these observations with models of eruptions and eruption-related phenomena. We also describe the SUVI data and discuss how the scientific community can access SUVI observations of the event.
How Many CMEs Have Flux Ropes? Deciphering the Signatures of Shocks, Flux Ropes, and Prominences in Coronagraph Observations of CMEs

We intend to provide a comprehensive answer to the question on whether all Coronal Mass Ejections (CMEs) have flux rope structure. To achieve this, we present a synthesis of the LASCO CME observations over the last 16 years, assisted by 3D MHD simulations of the breakout model, EUV and coronagraphic observations from STEREO and SDO, and statistics from a revised LASCO CME database. We argue that the bright loop often seen as the CME leading edge is the result of pileup at the boundary of the erupting flux rope irrespective of whether a cavity or, more generally, a three-part CME can be identified. Based on our previous work on white light shock detection and supported by the MHD simulations, we identify a new type of morphology, the ‘two-front’ morphology. It consists of a faint front followed by diffuse emission and the bright loop-like CME leading edge. We show that the faint front is caused by density compression at a wave (or possibly shock) front driven by the CME. We also present highly detailed multi-wavelength EUV observations that clarify the relative positioning of the prominence at the bottom of a coronal cavity with a clear flux rope structure. Finally, we visually check the full LASCO CME database for flux rope structures. In the process, we classify the events into two clear flux rope classes (‘three-part’, and ‘Loop’), jets and outflows (no clear structure). We find that at least 40 % of the observed CMEs have clear flux rope structures and that ∼ 29 % of the database entries are either misidentifications or inadequately measured and should be discarded from statistical analyses. We propose a new definition for flux rope CMEs (FR-CMEs) as a coherent magnetic, twist-carrying coronal structure with angular width of at least 40∘ and able to reach beyond 10 R⊙ which erupts on a time scale of a few minutes to several hours. We conclude that flux ropes are a common occurrence in CMEs and pose a challenge for future studies to identify CMEs that are clearly not FR-CMEs.
Continuous maximal regularity on uniformly regular Riemannian manifolds

We establish continuous maximal regularity results for parabolic differential operators acting on sections of tensor bundles on uniformly regular Riemannian manifolds M. As an application, we show that solutions to the Yamabe flow on M instantaneously regularize and become real analytic in space and time. The regularity result is obtained by introducing a family of parameter-dependent diffeomorphisms acting on functions on M in conjunction with maximal regularity and the implicit function theorem.
Efficient semiparametric estimation in generalized partially linear additive models for longitudinal/clustered data

We consider efficient estimation of the Euclidean parameters in a generalized partially linear additive models for longitudinal/clustered data when multiple covariates need to be modeled nonparametrically, and propose an estimation procedure based on a spline approximation of the nonparametric part of the model and the generalized estimating equations (GEE). Although the model in consideration is natural and useful in many practical applications, the literature on this model is very limited because of challenges in dealing with dependent data for nonparametric additive models. We show that the proposed estimators are consistent and asymptotically normal even if the covariance structure is misspecified. An explicit consistent estimate of the asymptotic variance is also provided. Moreover, we derive the semiparametric efficiency score and information bound under general moment conditions. By showing that our estimators achieve the semiparametric information bound, we effectively establish their efficiency in a stronger sense than what is typically considered for GEE. The derivation of our asymptotic results relies heavily on the empirical processes tools that we develop for the longitudinal/clustered data. Numerical results are used to illustrate the finite sample performance of the proposed estimators.
CYGNUS X-3's LITTLE FRIEND

Using the unique X-ray imaging capabilities of the Chandra X-ray observatory, a 2006 observation of Cygnus X-3 has provided insight into a singular feature associated with this well-known microquasar. This extended emission, located approx.16" from Cygnus X-3, varies in flux and orbital phase (shifted by 0.56 in phase) with Cygnus X-3, acting like a celestial X-ray "mirror." The feature s spectrum, flux, and time variations allow us to determine the location, size, density, and mass of the scatterer. We find that the scatterer is a Bok Globule located along our line of sight, and we discuss its relationship to Cygnus X-3. This is the first time such a feature has been identified with Chandra.
Rigidity for odd-dimensional souls

We prove a new rigidity result for an open manifold M with nonnegative sectional curvature whose soul U M is odd-dimensional. Specifically, there exists a geodesic in U and a parallel vertical plane field along it with constant vertical curvature and vanishing normal curvature. Under the added assumption that the Sharafutdinov fibers are rotationally symmetric, this implies that for small r , the distance sphere Br.U/Dfp2 M j dist.p;U/D rg contains an immersed flat cylinder, and thus could not have positive curvature. 53C20
Reinforcement Learning with Combinatorial Actions: An Application to Vehicle Routing

Value-function-based methods have long played an important role in reinforcement learning. However, finding the best next action given a value function of arbitrary complexity is nontrivial when the action space is too large for enumeration. We develop a framework for value-function-based deep reinforcement learning with a combinatorial action space, in which the action selection problem is explicitly formulated as a mixed-integer optimization problem. As a motivating example, we present an application of this framework to the capacitated vehicle routing problem (CVRP), a combinatorial optimization problem in which a set of locations must be covered by a single vehicle with limited capacity. On each instance, we model an action as the construction of a single route, and consider a deterministic policy which is improved through a simple policy iteration algorithm. Our approach is competitive with other reinforcement learning methods and achieves an average gap of 1.7% with state-of-the-art OR methods on standard library instances of medium size.
Far-Ultraviolet Spectroscopy of Venus and Mars at 4 Å Resolution with the Hopkins Ultraviolet Telescope on Astro-2

Far-ultraviolet spectra of Venus and Mars in the range 820-1840 A at ~4 A resolution were obtained on 1995 March 13 and 12, respectively, by the Hopkins Ultraviolet Telescope (HUT), which was part of the Astro-2 observatory on the space shuttle Endeavour. Longward of 1250 A, the spectra of both planets are dominated by emission of the CO fourth positive (A1Π-X1Σ+) band system and strong O I and C I multiplets. In addition, CO Hopfield-Birge bands, B1Σ+-X1Σ+ (0, 0) at 1151 A and C1Σ+-X1Σ+ (0, 0) at 1088 A, are detected for the first time, and there is a weak indication of the E1Π-X1Σ+ (0, 0) band at 1076 A in the spectrum of Venus. The B-X band is blended with emission from O I λ1152. Modeling the relative intensities of these bands suggests that resonance fluorescence of CO is the dominant source of the emission, as it is for the fourth positive system. Shortward of Lyα, other emission features detected include O II λ834, O I λ989, H I Lyβ, and N I λλ1134 and 1200. For Venus, the derived disk brightnesses of the O I, O II, and H I features are about one-half of those reported by Hord et al. from Galileo EUV measurements made in 1990 February. This result is consistent with the expected variation from solar maximum to solar minimum. The Ar I λλ1048, 1066 doublet is detected only in the spectrum of Mars, and the derived mixing ratio of Ar is of the order of 2%, consistent with previous determinations.
A Survey of the Molecular ISM Properties of Nearby Galaxies Using the Herschel FTS

The 12CO J = 4 ? 3 to J = 13 ? 12 lines of the interstellar medium from nearby galaxies, newly observable with the Herschel SPIRE Fourier transform spectrometer, offer an opportunity to study warmer, more luminous molecular gas than that traced by 12CO J = 1 ? 0. Here we present a survey of 17 nearby infrared-luminous galaxy systems (21 pointings). In addition to photometric modeling of dust, we modeled full 12CO spectral line energy distributions from J = 1 ? 0 to J = 13 ? 12 with two components of warm and cool CO gas, and included LTE analysis of [C I], [C II], [N II], and H2 lines. CO is emitted from a low-pressure/high-mass component traced by the low-J lines and a high-pressure/low-mass component that dominates the luminosity. We found that, on average, the ratios of the warm/cool pressure, mass, and 12CO luminosity are 60 ? 30, 0.11 ? 0.02, and 15.6 ? 2.7. The gas-to-dust-mass ratios are <120 throughout the sample. The 12CO luminosity is dominated by the high-J lines and is 4 ? 10?4 L FIR on average. We discuss systematic effects of single-component and multi-component CO modeling (e.g., single-component J ? 3 models overestimate gas pressure by ~0.5 dex), as well as compare to Galactic star-forming regions. With this comparison, we show the molecular interstellar medium of starburst galaxies is not simply an ensemble of Galactic-type giant molecular clouds. The warm gas emission is likely dominated by regions resembling the warm extended cloud of Sgr B2.
From Discrepancy to Majority

We show how to select an item with the majority color from n two-colored items, given access to the items only through an oracle that returns the discrepancy of subsets of k items (the absolute value of the difference between the numbers of items with each color). We use \(n/\lfloor \tfrac{k}{2}\rfloor +O(k)\) queries, improving a previous method by De Marco and Kranakis that used \(n-k+k^2/2\) queries. We also prove a lower bound of \(n/(k-1)-O (n^{1/3})\) on the number of queries needed, both for discrepancy queries and to queries that return the partition of items into monochromatic subsets. This improves a lower bound of \(\lfloor n/k\rfloor \) by De Marco and Kranakis.
Counting points of fixed degree and bounded height

We consider the set of points in projective n-space that generate an extension of degree e over given number field k, and deduce an asymptotic formula for the number of such points of absolute height at most X, as X tends to infinity. We deduce a similar such formula with instead of the absolute height, a so-called adelic-Lipschitz height.
Misleading Signposts Along the de Broglie-Bohm Road to Quantum Mechanics

Eighty years after de Broglie’s, and a little more than half a century after Bohm’s seminal papers, the de Broglie–Bohm theory (a.k.a. Bohmian mechanics), which is presumably the simplest theory which explains the orthodox quantum mechanics formalism, has reached an exemplary state of conceptual clarity and mathematical integrity. No other theory of quantum mechanics comes even close. Yet anyone curious enough to walk this road to quantum mechanics is soon being confused by many misleading signposts that have been put up, and not just by its detractors, but unfortunately enough also by some of its proponents. This paper outlines a road map to help navigate ones way.
Structure, mechanical and thermodynamic stability of vacancy clusters in Cu

The atomic structure, mechanical and thermodynamic stability of vacancy clusters in Cu are studied by atomistic simulations. The most stable atomic configuration of small vacancy clusters is determined. The mechanical stability of the vacancy clusters is examined by applying uniaxial and volumetric tensile strains to the system. The yield stress and yield strain of the system are significantly reduced compared with the perfect lattice. The dependence of vacancy formation and binding energy as a function of strain is explored and can be understood from the liquid-drop model. We find that the formation energy of the vacancy clusters decreases monotonically as a function of the uniaxial strain, while the formation energy increases first then decreases under the volumetric tensile strain. The thermodynamic stability of the vacancy clusters is analyzed by calculating the Helmholtz free binding energy and the total probability of dissociation of the vacancy clusters at 300 and 900 K under uniaxial and volumetric strains. We find that although most of the vacancy clusters appear to be thermodynamically stable, some of the intermediate sized clusters have a high probability of dissociation into smaller clusters.
On the Hohenberg-Mermin-Wagner Theorem and Its Limitations

Just over 50 years ago, Pierre Hohenberg developed a rigorous proof of the non-existence of long-range order in a two-dimensional superfluid or superconductor at finite temperatures. The proof was immediately extended by Mermin and Wagner to the Heisenberg ferromagnet and antiferromagnet, and shortly thereafter, by Mermin to prove the absence of translational long-range order in a two-dimensional crystal, whether in quantum or classical mechanics. In this paper, we present an extension of the Hohenberg–Mermin–Wagner theorem to give a rigorous proof of the impossibility of long-range ferromagnetic order in an itinerant electron system without spin-orbit coupling or magnetic dipole interactions. We also comment on some situations where there are compelling arguments that long-range order is impossible but no rigorous proof has been given, as well as situations, such as a magnet with long range interactions, or orientational order in a two-dimensional crystal, where long-range order can occur that breaks a continuous symmetry.
TURBULENT, EXTREME MULTI-ZONE MODEL FOR SIMULATING FLUX AND POLARIZATION VARIABILITY IN BLAZARS

The author presents a model for variability of the flux and polarization of blazars in which turbulent plasma flowing at a relativistic speed down a jet crosses a standing conical shock. The shock compresses the plasma and accelerates electrons to energies up to γmax 104 times their rest-mass energy, with the value of γmax determined by the direction of the magnetic field relative to the shock front. The turbulence is approximated in a computer code as many cells, each with a uniform magnetic field whose direction is selected randomly. The density of high-energy electrons in the plasma changes randomly with time in a manner consistent with the power spectral density of flux variations derived from observations of blazars. The variations in flux and polarization are therefore caused by continuous noise processes rather than by singular events such as explosive injection of energy at the base of the jet. Sample simulations illustrate the behavior of flux and linear polarization versus time that such a model produces. The variations in γ-ray flux generated by the code are often, but not always, correlated with those at lower frequencies, and many of the flares are sharply peaked. The mean degree of polarization of synchrotron radiation is higher and its timescale of variability shorter toward higher frequencies, while the polarization electric vector sometimes randomly executes apparent rotations. The slope of the spectral energy distribution exhibits sharper breaks than can arise solely from energy losses. All of these results correspond to properties observed in blazars.
Horowitz–Randol pairs of curves in q–differential metrics

The Euclidean cone metrics coming from q ‐differentials on a closed surface of genus g 2 define an equivalence relation on homotopy classes of closed curves, where two classes are equivalent if they have the equal length in every such metric. We prove an analogue of the result of Randol for hyperbolic metrics (building on the work of Horowitz): for every integer q 1, the corresponding equivalence relation has arbitrarily large equivalence classes. In addition, we describe how these equivalence relations are related to each other. 57M50
Modification of light transmission channels by inhomogeneous absorption in random media

Optical absorption is omnipresent and often distributed non-uniformly in space. We present a numerical study on the effects of inhomogeneous absorption on transmission eigenchannels of light in highly scattering media. In the weak absorption regime, the spatial profile of a transmission channel remains similar to that without absorption, and the effect of inhomogeneous absorption can be stronger or weaker than homogeneous absorption depending on the spatial overlap of the localized absorbing region with the field intensity maximum of the channel. In the strong absorption regime, the high transmission channels redirect the energy flows to circumvent the absorbing regions to minimize loss. The attenuation of high transmission channels by inhomogeneous absorption is lower than that by homogeneous absorption, regardless of the location of the absorbing region. The statistical distribution of transmission eigenvalues in the former becomes broader than that in the latter, due to a longer tail at high transmission. The maximum enhancement factor of total transmission increases with absorption, eventually exceeds that without absorption.
Mathematical toy model inspired by the problem of the adaptive origins of the sexual orientation continuum.

Same-sex sexual behaviour is ubiquitous in the animal kingdom, but its adaptive origins remain a prominent puzzle. Here, I suggest the possibility that same-sex sexual behaviour arises as a consequence of the competition between an evolutionary drive for a wide diversity in traits, which improves the adaptability of a population, and a drive for sexual dichotomization of traits, which promotes opposite-sex attraction and increases the rate of reproduction. This trade-off is explored via a simple mathematical ‘toy model’. The model exhibits a number of interesting features and suggests a simple mathematical form for describing the sexual orientation continuum.
ALMA OBSERVATIONS OF THE LARGEST PROTO-PLANETARY DISK IN THE ORION NEBULA, 114–426: A CO SILHOUETTE

We present ALMA observations of the largest protoplanetary disk in the Orion Nebula, 114–426. Detectable 345 GHz (856 μm) dust continuum is produced only in the 350 AU central region of the ~1000 AU diameter silhouette seen against the bright Hα background in Hubble Space Telescope images. Assuming optically thin dust emission at 345 GHz, a gas-to-dust ratio of 100, and a grain temperature of 20 K, the disk gas-mass is estimated to be 3.1±0.6 Jupiter masses. If most solids and ices have been incorporated into large grains, however, this value is a lower limit. The disk is not detected in dense-gas tracers such as HCO^+ J = 4–3, HCN J = 4–3, or CS = 7–6. These results may indicate that the 114–426 disk is evolved and depleted in some light organic compounds found in molecular clouds. The CO J = 3–2 line is seen in absorption against the bright 50–80 K background of the Orion A molecular cloud over the full spatial extent and a little beyond the dust continuum emission. The CO absorption reaches a depth of 27 K below the background CO emission at V_LSR ≈ 6.7 km s^-1 ~ 0".52 (210 AU) northeast and 12 K below the background CO emission at V_LSR ≈ 9.7 km s^-1 ~ 0".34 (140 AU) southwest of the suspected location of the central star, implying that the embedded star has a mass less than 1 M_⊙.
From Hot Jupiters to Super-Earths via Roche Lobe Overflow

Through tidal dissipation in a slowly spinning host star, the orbits of many hot Jupiters may decay down to the Roche limit. We expect that the ensuing mass transfer will be stable in most cases. Using detailed numerical calculations, we find that this evolution is quite rapid, potentially leading to the complete removal of the gaseous envelope in a few gigayears, and leaving behind an exposed rocky core (a {sup h}ot super-Earth{sup )}. Final orbital periods are quite sensitive to the details of the planet's mass-radius relation and to the effects of irradiation and photo-evaporation, but could be as short as a few hours or as long as several days. Our scenario predicts the existence of planets with intermediate masses ({sup h}ot Neptunes{sup )} that should be found precisely at their Roche limit and in the process of losing mass through Roche lobe overflow. The observed excess of small single-planet candidate systems observed by Kepler may also be the result of this process. If so, the properties of their host stars should track those of the hot Jupiters. Moreover, the number of systems that produced hot Jupiters could be two to three times larger than one would infer from contemporarymore » observations.« less
Toward the jamming threshold of sphere packings: Tunneled crystals

We have discovered a family of three-dimensional crystal sphere packings that are strictly jammed (i.e., mechanically stable) and yet possess an anomalously low density. This family constitutes an uncountably infinite number of crystal packings that are subpackings of the densest crystal packings and are characterized by a high concentration of self-avoiding “tunnels” (chains of vacancies) that permeate the structures. The fundamental geometric characteristics of these tunneled crystals command interest in their own right and are described here in some detail. These include the lattice vectors (that specify the packing configurations), coordination structure, Voronoi cells, and density fluctuations. The tunneled crystals are not only candidate structures for achieving the jamming threshold (lowest-density rigid packing), but may have substantially broader significance for condensed matter physics and materials science.
The Branching Ratio of LIGO Binary Black Holes

Formation of binary black holes (BBHs) detected by gravitational-wave (GW) observations could be broadly divided into two categories: those formed through field binary evolution and those assembled dynamically in dense stellar systems. The branching ratio of the BBHs refers to the contribution of each channel. The dynamical assembly channel would predict a symmetric distribution in the effective spins of the BBHs while field formation predicts BBHs to have positive effective spins. By modeling these two populations based on their effective spin distribution we show that in the 10 BBHs detected by LIGO/Virgo the contribution of the dynamically assembled BBHs to be more than about 50\% with 90\% confidence. This result is based on the assumption that the field binaries are born with positive effective spins not restricted to have small values.
Monitoring the atmospheric throughput at Cerro Tololo Inter-American Observatory with aTmCam

We have built an Atmospheric Transmission Monitoring Camera (aTmCam), which consists of four telescopes and detectors each with a narrow-band filter that monitors the brightness of suitable standard stars. Each narrowband filter is selected to monitor a different wavelength region of the atmospheric transmission, including regions dominated by the precipitable water vapor and aerosol optical depth. The colors of the stars are measured by this multi narrow-band imager system simultaneously. The measured colors, a model of the observed star, and the measured throughput of the system can be used to derive the atmospheric transmission of a site on sub-minute time scales. We deployed such a system to the Cerro Tololo Inter-American Observatory (CTIO) and executed two one-month-long observing campaigns in Oct-Nov 2012 and Sept-Oct 2013. We have determined the time and angular scales of variations in the atmospheric transmission above CTIO during these observing runs. We also compared our results with those from a GPS Water Vapor Monitoring System and find general agreement. The information for the atmospheric transmission can be used to improve photometric precision of large imaging surveys such as the Dark Energy Survey and the Large Synoptic Survey Telescope.
Three-Dimensional Relativistic Magnetohydrodynamic Simulations of Current-Driven Instability with A Sub-Alfvenic Jet: Temporal Properties

We have investigated the influence of a velocity shear surface on the linear and nonlinear development of the current-driven (CD) kink instability of force-free helical magnetic equilibria in three dimensions. In this study, we follow the temporal development within a periodic computational box and concentrate on flows that are sub-Alfvenic on the cylindrical jet's axis. Displacement of the initial force-free helical magnetic field leads to the growth of CD kink instability. We find that helically distorted density structure propagates along the jet with speed and flow structure dependent on the radius of the velocity shear surface relative to the characteristic radius of the helically twisted force-free magnetic field. At small velocity shear surface radius, the plasma flows through the kink with minimal kink propagation speed. The kink propagation speed increases as the velocity shear radius increases and the kink becomes more embedded in the plasma flow. A decreasing magnetic pitch profile and faster flow enhance the influence of velocity shear. Simulations show continuous transverse growth in the nonlinear phase of the instability. The growth rate of the CD kink instability and the nonlinear behavior also depend on the velocity shear surface radius and flow speed, and the magnetic pitch radial profile. Larger velocity shear radius leads to slower linear growth, makes a later transition to the nonlinear stage, and with larger maximum amplitude than that occuring for a static plasma column. However, when the velocity shear radius is much greater than the characteristic radius of the helical magnetic field, linear and nonlinear development can be similar to the development of a static plasma column.
Geometric combinatorial algebras: cyclohedron and simplex

In this paper we report on results of our investigation into the algebraic structure supported by the combinatorial geometry of the cyclohedron. Our new graded algebra structures lie between two well known Hopf algebras: the Malvenuto---Reutenauer algebra of permutations and the Loday---Ronco algebra of binary trees. Connecting algebra maps arise from a new generalization of the Tonks projection from the permutohedron to the associahedron, which we discover via the viewpoint of the graph associahedra of Carr and Devadoss. At the same time, that viewpoint allows exciting geometrical insights into the multiplicative structure of the algebras involved. Extending the Tonks projection also reveals a new graded algebra structure on the simplices. Finally this latter is extended to a new graded Hopf algebra with basis all the faces of the simplices.
How does clustering depend on environment

According to the current paradigm, galaxies form and reside in extended cold dark matter (CDM) halos and in turn are key tracers of cosmological structure. Understanding how different types of galaxies occupy halos of different masses is one of the major challenges facing extragalactic astrophysics. The observed galaxy properties depend on the environment surrounding the galaxy. Within the framework of most galaxy formation models the environmental dependence of the galaxy population is mainly due to the change of the halo mass function with large-scale environment. Such models make precise predictions for how galaxy clustering should depend on environment. We will illustrate this by presenting analytical models of dark matter and galaxy clustering along with results obtained from numerical simulations. With these results we can hope to obtain a better understanding of the link between galaxies and dark matter and thereby constrain galaxy formation models. To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html