cssi/SciSciGPT-SciSciNet huggingface dataset:
The Carnegie Hubble Program: The Distance and Structure of the SMC as Revealed by Mid-infrared Observations of Cepheids

Using Spitzer observations of classical Cepheids we have measured the true average distance modulus of the Small Magellanic Cloud (SMC) to be18.96 +/- 0.01 stat +/- 0.03sys mag (corresponding to 62+/- 0.3kpc), which is 0.48 +/- 0.01 mag more distant than the LMC. This is in agreement with previous results from Cepheid observations, as well as with measurements from other indicators such as RR Lyrae stars and the tip of the red giant branch. Utilizing the properties of the mid-infrared Leavitt Law we measured precise distances to individual Cepheids in the SMC, and have confirmed that the galaxy is tilted and elongated such that its eastern side is up to20 kpc closer than its western side. This is in agreement with the results from red clump stars and dynamical simulations of the Magellanic Clouds and Stream.
The ratio of microwaves to X-rays in solar flares - The case for the thick-target model

The expected ratio of synchrotron microwave radiation to bremsstrahlung X-rays for thick target, thin target, and multithermal solar flare models is calculated. The calculations take into account the variation of the microwave to X-ray ratio with X-ray spectral index. The theoretical results are compared with observed ratios of a sample of 51 solar flares with well known spectral index. From this it is concluded that the nonthermal thick target model with a loop length of and order of 10 to the 9th power cm and a magnetic field of 500 + or - 200 G provides the best fit to the data. The thin target and multithermal models require unreasonably large density or pressure and/or low magnetic field to match the data. 22 references.
Deformably registering and annotating whole CLARITY brains to an atlas via masked LDDMM

The CLARITY method renders brains optically transparent to enable high-resolution imaging in the structurally intact brain. Anatomically annotating CLARITY brains is necessary for discovering which regions contain signals of interest. Manually annotating whole-brain, terabyte CLARITY images is difficult, time-consuming, subjective, and error-prone. Automatically registering CLARITY images to a pre-annotated brain atlas offers a solution, but is difficult for several reasons. Removal of the brain from the skull and subsequent storage and processing cause variable non-rigid deformations, thus compounding inter-subject anatomical variability. Additionally, the signal in CLARITY images arises from various biochemical contrast agents which only sparsely label brain structures. This sparse labeling challenges the most commonly used registration algorithms that need to match image histogram statistics to the more densely labeled histological brain atlases. The standard method is a multiscale Mutual Information B-spline algorithm that dynamically generates an average template as an intermediate registration target. We determined that this method performs poorly when registering CLARITY brains to the Allen Institute's Mouse Reference Atlas (ARA), because the image histogram statistics are poorly matched. Therefore, we developed a method (Mask-LDDMM) for registering CLARITY images, that automatically finds the brain boundary and learns the optimal deformation between the brain and atlas masks. Using Mask-LDDMM without an average template provided better results than the standard approach when registering CLARITY brains to the ARA. The LDDMM pipelines developed here provide a fast automated way to anatomically annotate CLARITY images; our code is available as open source software at http://NeuroData.io.
Weibel's conjecture for twisted $K$-theory

We prove Weibel’s conjecture for twisted K-theory when twisting by a smooth proper connective dg-algebra. Our main contribution is showing we can kill a negative twisted K-theory class using a projective birational morphism (in the same twisted setting). We extend the vanishing result to relative twisted K-theory of a smooth affine morphism and describe counterexamples to some similar extensions.
A Search for Variability in the Active T Dwarf 2MASS 1237+6526

We present spectroscopic and imaging observations of the active T dwarf 2MASS 1237+6526, intended to investigate the emission mechanism of this cool brown dwarf. The H? emission line, first detected in 1999 July, appears to be persistent over 1.6 yr, with no significant variation from (LH?/Lbol) = -4.3, ruling out flaring as a possible source. The relatively high level of emission in this object appears to be unique among observed late-L and T dwarfs. One of our spectra shows an apparent velocity shift in the H? line, which could indicate an accretion hot spot in orbit around the brown dwarf; further confirmation of this shift is required. J-band monitoring observations fail to detect any significant variability (e.g., eclipsing events) at the ?0.025 mag level over periods of up to 2.5 hr, and there appears to be no statistical evidence of variability for periods of up to 14 hr. These limits constrain the mass of a hypothetical interacting secondary to M2 20 MJup for inclinations i 60?. While our observations do not explicitly rule out the binary hypothesis for this object, it does suggest that other mechanisms, such as youthful accretion, may be responsible.
Astronomical tests for quantum black hole structure

Black holes present a profound challenge to our current foundations of physics, and an exciting era of astronomy is just opening in which gravitational-wave observation and very-long-baseline interferometry may provide important hints about the new principles of physics needed.
Multi-scale gradient expansion of the turbulent stress tensor

Turbulent stress is the fundamental quantity in the filtered equation for large-scale velocity that reflects its interactions with small-scale velocity modes. We develop an expansion of the turbulent stress tensor into a double series of contributions from different scales of motion and different orders of space derivatives of velocity, a multi-scale gradient (MSG) expansion. We compare our method with a somewhat similar expansion that is based instead on defiltering. Our MSG expansion is proved to converge to the exact stress, as a consequence of the locality of cascade both in scale and in space. Simple estimates show, however, that the convergence rate may be slow for the expansion in spatial gradients of very small scales. Therefore, we develop an approximate expansion, based upon an assumption that similar or ‘coherent’ contributions to turbulent stress are obtained from disjoint subgrid regions. This coherent-subregions approximation (CSA) yields an MSG expansion that can be proved to converge rapidly at all scales and is hopefully still reasonably accurate. As an important first application of our methods, we consider the cascades of energy and helicity in three-dimensional turbulence. To first order in velocity gradients, the stress has three contributions: a tensile stress along principal directions of strain, a contractile stress along vortex lines, and a shear stress proportional to ‘skew-strain’. While vortex stretching plays the major role in energy cascade, there is a second, less scale-local contribution from ‘skew-strain’. For helicity cascade the situation is reversed, and it arises scale-locally from ‘skew-strain’ while the stress along vortex lines gives a secondary, less scale-local contribution. These conclusions are illustrated with simple exact solutions of three-dimensional Euler equations. In the first, energy cascade occurs by Taylor's mechanism of stretching and spin-up of small-scale vortices owing to large-scale strain. In the second, helicity cascade occurs by ‘twisting’ of small-scale vortex filaments owing to a large-scale screw.
THE DEGREE PROFILE AND GINI INDEX OF RANDOM CATERPILLAR TREES

In this paper, we investigate the degree profile and Gini index of random caterpillar trees (RCTs). We consider RCTs which evolve in two different manners: uniform and nonuniform. The degrees of the vertices on the central path (i.e., the degree profile) of a uniform RCT follows a multinomial distribution. For nonuniform RCTs, we focus on those growing in the fashion of preferential attachment. We develop methods based on stochastic recurrences to compute the exact expectations and the dispersion matrix of the degree variables. A generalized Polya urn model is exploited to determine the exact joint distribution of these degree variables. We apply the methods from combinatorics to prove that the asymptotic distribution is Dirichlet. In addition, we propose a new type of Gini index to quantitatively distinguish the evolutionary characteristics of the two classes of RCTs. We present the results via several numerical experiments.
RRPN: Radar Region Proposal Network for Object Detection in Autonomous Vehicles

Region proposal algorithms play an important role in most state-of-the-art two-stage object detection networks by hypothesizing object locations in the image. Nonetheless, region proposal algorithms are known to be the bottleneck in most two-stage object detection networks, increasing the processing time for each image and resulting in slow networks not suitable for real-time applications such as autonomous driving vehicles. In this paper we introduce RRPN, a Radar-based real-time region proposal algorithm for object detection in autonomous driving vehicles. RRPN generates object proposals by mapping Radar detections to the image coordinate system and generating pre-defined anchor boxes for each mapped Radar detection point. These anchor boxes are then transformed and scaled based on the object’s distance from the vehicle, to provide more accurate proposals for the detected objects. We evaluate our method on the newly released NuScenes dataset [1] using the Fast R-CNN object detection network [2]. Compared to the Selective Search object proposal algorithm [3], our model operates more than 100× faster while at the same time achieves higher detection precision and recall. Code has been made publicly available at https://github.com/mrnabati/RRPN.
Polynomial partitioning for a set of varieties

Given a set Γ of low-degree k-dimensional varieties in n , we prove that for any D ⩾ 1, there is a non-zero polynomial P of degree at most D so that each component of n \Z(P) intersects O(Dk−n |Γ|) varieties of Γ.
Ground state entropy in Potts antiferromagnets and chromatic polynomials

We discuss recent results on ground state entropy in Potts antiferromagnets and connections with chromatic polynomials. These include rigorous lower and upper bounds, Monte Carlo measurements, large-q series, exact solutions, and studies of analytic properties. Some related results on Fisher zeros of Potts models are also mentioned.
Calcium-rich Gap Transients: Solving the Calcium Conundrum in the Intracluster Medium

X-ray measurements suggest that the abundance of calcium in the intracluster medium is higher than can be explained using favored models for core-collapse and Type Ia supernovae alone. We investigate whether the "calcium conundrum" in the intracluster medium can be alleviated by including a contribution from the recently discovered subclass of supernovae known as calcium-rich gap transients. Although the calcium-rich gap transients make up only a small fraction of all supernovae events, we find that their high calcium yields are sufficient to reproduce the X-ray measurements found for nearby rich clusters. We find the χ2 goodness-of-fit metric improves from 84 to 2 by including this new class. Moreover, calcium-rich supernovae preferentially occur in the outskirts of galaxies making it easier for the nucleosynthesis products of these events to be incorporated in the intracluster medium via ram-pressure stripping. The discovery of calcium-rich gap transients in clusters and groups far from any individual galaxy suggests that supernovae associated with intracluster stars may play an important role in enriching the intracluster medium. Calcium-rich gap transients may also help explain anomalous calcium abundances in many other astrophysical systems including individual stars in the Milky Way, the halos of nearby galaxies, and the circumgalactic medium. Our work highlights the importance of considering the diversity of supernovae types and corresponding yields when modeling the abundance of the intracluster medium and other gas reservoirs.
Ensemble-based topological entropy calculation (E-tec)

Topological entropy measures the number of distinguishable orbits in a dynamical system, thereby quantifying the complexity of chaotic dynamics. One approach to computing topological entropy in a two-dimensional space is to analyze the collective motion of an ensemble of system trajectories taking into account how trajectories "braid" around one another. In this spirit, we introduce the Ensemble-based Topological Entropy Calculation, or E-tec, a method to derive a lower-bound on topological entropy of two-dimensional systems by considering the evolution of a "rubber band" (piece-wise linear curve) wrapped around the data points and evolving with their trajectories. The topological entropy is bounded below by the exponential growth rate of this band. We use tools from computational geometry to track the evolution of the rubber band as data points strike and deform it. Because we maintain information about the configuration of trajectories with respect to one another, updating the band configuration is performed locally, which allows E-tec to be more computationally efficient than some competing methods. In this work, we validate and illustrate many features of E-tec on a chaotic lid-driven cavity flow. In particular, we demonstrate convergence of E-tec's approximation with respect to both the number of trajectories (ensemble size) and the duration of trajectories in time.
Separating Physical Components from Galaxy Spectra by Subspace Methods

Using subspace methods, we study the distribution of physical components of galaxies in wavelength space. We find that it is valid to assume that the stellar and the gaseous components of galaxies span complementary subspaces. To first order, stellar and gaseous spectral features can be extracted from galaxy spectra through a simple matrix multiplication. By comparing the stellar continua obtained respectively using the model-based and the empirical approach through a commonality measure, we conclude that the latter may lose higher-order spectral features.
Multipoint conformal blocks in the comb channel

Conformal blocks are the building blocks for correlation functions in conformal field theories. The four-point function is the most well-studied case. We consider conformal blocks for n-point correlation functions. For conformal field theories in dimensions d = 1 and d = 2, we use the shadow formalism to compute n-point conformal blocks, for arbitrary n, in a particular channel which we refer to as the comb channel. The result is expressed in terms of a multivariable hypergeometric function, for which we give series, differential, and integral representations. In general dimension d we derive the 5-point conformal block, for external and exchanged scalar operators.
The cosmic horizon

The cosmological principle, promoting the view that the Universe is homogeneous and isotropic, is embodied within the mathematical structure of the Robertson‐Walker (RW) metric. The equations derived from an application of this metric to the Einstein Field Equations describe the expansion of the Universe in terms of comoving coordinates, from which physical distances may be derived using a time-dependent expansion factor. These coordinates, however, do not explicitly reveal the properties of the cosmic space‐time manifested in Birkhoff’s theorem and its corollary. In this paper, we compare two forms of the metric ‐ written in (the traditional) comoving coordinates, and a set of observer-dependent coordinates ‐ first for the well-known de Sitter universe containing only dark energy, and then for a newly derived form of the RW metric, for a universe with dark energy and matter. We show that Rindler’s event horizon ‐ evident in the comoving system ‐ coincides with what one might call the ‘curvature horizon’ appearing in the observer-dependent frame. The advantage of this dual prescription of the cosmic space‐time is that with the latest Wilkinson Microwave Anisotropy Probe results, we now have a much better determination of the Universe’s mass-energy content, which permits us to calculate this curvature with unprecedented accuracy. We use it here to demonstrate that our observations have probed the limit beyond which the cosmic curvature prevents any signal from having ever reached us. In the case of de Sitter, where the mass-energy density is a constant, this limit is fixed for all time. For a universe with a changing density, this horizon expands until de Sitter is reached asymptotically, and then it too ceases to change.
Idempotent functors that preserve cofiber sequences and split suspensions

We show that an f –localization functor Lf commutes with cofiber sequences of .N 1/–connected finite complexes if and only if its restriction to the collection of .N 1/–connected finite complexes is R–localization for some unital subring R Q . This leads to a homotopy theoretical characterization of the rationalization functor: the restriction of Lf to simply connected spaces (not just the finite complexes) is rationalization if and only if Lf .S/ is nontrivial and simply connected, Lf preserves cofiber sequences of simply connected finite complexes and for each simply connected finite complex K , there is a k such that †Lf .K/ splits as a wedge of copies of Lf .S/ for various values of n .
Phurbas: An Adaptive, Lagrangian, Meshless, Magnetohydrodynamics Code. I. Algorithm

We present an algorithm for simulating the equations of ideal magnetohydrodynamics and other systems of differential equations on an unstructured set of points represented by sample particles. Local, third-order, least-squares, polynomial interpolations (Moving Least Squares interpolations) are calculated from the field values of neighboring particles to obtain field values and spatial derivatives at the particle position. Field values and particle positions are advanced in time with a second-order predictor-corrector scheme. The particles move with the fluid, so the time step is not limited by the Eulerian Courant-Friedrichs-Lewy condition. Full spatial adaptivity is implemented to ensure the particles fill the computational volume, which gives the algorithm substantial flexibility and power. A target resolution is specified for each point in space, with particles being added and deleted as needed to meet this target. Particle addition and deletion is based on a local void and clump detection algorithm. Dynamic artificial viscosity fields provide stability to the integration. The resulting algorithm provides a robust solution for modeling flows that require Lagrangian or adaptive discretizations to resolve. This paper derives and documents the Phurbas algorithm as implemented in Phurbas version 1.1. A following paper presents the implementation and test problem results.
Essential Observations of the Lyman Continuum

Concurrent observations of Lyman continuum (LyC) and Lyman α (Lyα) emission escaping from star‐forming systems at low redshift are essential to understanding the physics of reionization at high redshift (z≳6). Some have suggested reionization is dominated by numerous small galaxies with LyC escape fractions fe∼10%, while others suggest mini‐quasars with higher fe might also play a role. At z>3, direct observation of LyC leakage becomes progressively more improbable due to the increase of intervening Ly limit systems, leaving Lyα as the primary diagnostic available to the James Webb Space Telescope for exploring the epoch of reionization. If a quantitative relationship between escaping LyC and Lyα emission can be established at low z, then the diagnostic power of Lyα as a LyC proxy at high z can be fully realized. Past efforts to detect fe near z≈3 have been fruitful but observations at low redshift have been less so. We discuss the sensitivity requirements for detecting LyC leak in the far‐ and near‐UV as...
Buoyancy instabilities in galaxy clusters: convection due to adiabatic cosmic rays and anisotropic thermal conduction

Using a linear stability analysis and two- and three-dimensional nonlinear simulations, we study the physics of buoyancy instabilities in a combined thermal and relativistic (cosmic ray) plasma, motivated by the application to clusters of galaxies. We argue that the cosmic-ray diffusion time is likely to be long compared to the buoyancy time on large length scales, so that cosmic rays are effectively adiabatic. If the cosmic-ray pressure p cr is 25% of the thermal pressure, and the cosmic-ray "entropy" p cr/ρ4/3 (where ρ is the thermal-plasma density) decreases outward, cosmic rays drive an adiabatic convective instability analogous to Schwarzschild convection in stars. Global simulations of galaxy cluster cores show that this instability saturates by reducing the cosmic-ray entropy gradient and driving efficient convection and turbulent mixing. At larger radii in cluster cores where cosmic-ray pressure is negligible, the thermal plasma is unstable to the heat-flux-driven buoyancy instability (HBI), a convective instability generated by anisotropic thermal conduction and a background conductive heat flux. The HBI saturates by rearranging the magnetic field lines to become largely perpendicular to the local gravitational field; the resulting turbulence also primarily mixes plasma in the perpendicular plane. Cosmic-ray-driven convection and the HBI may contribute to redistributing metals produced by Type Ia supernovae in clusters. Our calculations demonstrate that adiabatic simulations of galaxy clusters can artificially suppress the mixing of thermal plasma. When anisotropic thermal conduction is included, the buoyant response of the thermal plasma is not governed by the stable entropy gradient, and mixing (driven by mergers, cosmic ray buoyancy, etc.) is more effective. Such mixing may contribute to cosmic rays being distributed throughout the cluster volume.
Examples of expanding endomorphisms on fake tori

We construct expanding endomorphisms on smooth manifolds that are homeomorphic to tori yet have exotic underlying PL-structures.
Neutron stars and supernova explosions in the framework of Landau's theory

In this paper, a general formula of the symmetry energy for many-body interaction is proposed and the commonly used two-body interaction symmetry energy is recovered. Within Landau's theory (Lt), we generalize two equations of state (EoS) CCSδ3 and CCSδ5 to asymmetric nuclear matter. We assume that the density and density difference between protons and neutrons divided by their sum are order parameters. We use different EoS to study neutron stars by solving the TOV equations. We demonstrate that different EoS give different mass and radius relation for neutron stars even when they have exactly the same ground state (gs) properties (E/A, ρ0, K, S, L and Ksym). Furthermore, for one EoS we change Ksym and fix all the other gs parameters. We find that for some Ksym the EoS becomes unstable at high density even for neutron matter. This suggests that a neutron star (NS) can exist below and above the instability region but in different states: a quark gluon plasma (QGP) at high density and baryonic matter at low density. If the star's central density is in the instability region, then we associate these conditions to the occurrence of supernovae (SN).
Continual Adaptation for Efficient Machine Communication

To communicate with new partners in new contexts, humans rapidly form new linguistic conventions. Recent neural language models are able to comprehend and produce the existing conventions present in their training data, but are not able to flexibly and interactively adapt those conventions on the fly as humans do. We introduce an interactive repeated reference task as a benchmark for models of adaptation in communication and propose a regularized continual learning framework that allows an artificial agent initialized with a generic language model to more accurately and efficiently communicate with a partner over time. We evaluate this framework through simulations on COCO and in real-time reference game experiments with human partners.
The Formation Of The First Stars In The Universe

In this review, I survey our current understanding of how the very first stars in the universe formed, with a focus on three main areas of interest: the formation of the first protogalaxies and the cooling of gas within them, the nature and extent of fragmentation within the cool gas, and the physics – in particular the interplay between protostellar accretion and protostellar feedback – that serves to determine the final stellar mass. In each of these areas, I have attempted to show how our thinking has developed over recent years, aided in large part by the increasing ease with which we can now perform detailed numerical simulations of primordial star formation. I have also tried to indicate the areas where our understanding remains incomplete, and to identify some of the most important unsolved problems.
Sites of vulnerability on ricin B chain revealed through epitope mapping of toxin-neutralizing monoclonal antibodies.

Ricin toxin’s B subunit (RTB) is a multifunctional galactose (Gal)-/N-acetylgalactosamine (GalNac)-specific lectin that promotes uptake and intracellular trafficking of ricin’s ribosome-inactivating subunit (RTA) into mammalian cells. Structurally, RTB consists of two globular domains (RTB-D1, RTB-D2), each divided into three homologous sub-domains (α, β, γ). The two carbohydrate recognition domains (CRDs) are situated on opposite sides of RTB (sub-domains 1α and 2γ) and function non-cooperatively. Previous studies have revealed two distinct classes of toxin-neutralizing, anti-RTB monoclonal antibodies (mAbs). Type I mAbs, exemplified by SylH3, inhibit (~90%) toxin attachment to cell surfaces, while type II mAbs, epitomized by 24B11, interfere with intracellular toxin transport between the plasma membrane and the trans-Golgi network (TGN). Localizing the epitopes recognized by these two classes of mAbs has proven difficult, in part because of RTB’s duplicative structure. To circumvent this problem, RTB-D1 and RTB-D2 were expressed as pIII fusion proteins on the surface of filamentous phage M13 and subsequently used as “bait” in mAb capture assays. We found that SylH3 captured RTB-D1 (but not RTB-D2) in a dose-dependent manner, while 24B11 captured RTB-D2 (but not RTB-D1) in a dose-dependent manner. We confirmed these domain assignments by competition studies with an additional 8 RTB-specific mAbs along with a dozen a single chain antibodies (VHHs). Collectively, these results demonstrate that type I and type II mAbs segregate on the basis of domain specificity and suggest that RTB’s two domains may contribute to distinct steps in the intoxication pathway.
Large-density field theory, viscosity, and '$2k_F$' singularities from string duals

We analyze systems where an effective large-N expansion arises naturally in gauge theories without a large number of colors: a sufficiently large charge density alone can produce a perturbative string ('tHooft) expansion. One example is simply the well-known NS5/F1 system dual to AdS3 ? T4 ? S3, here viewed as a 5+1 dimensional theory at finite density. This model is completely stable, and we find that the existing string-theoretic solution of this model yields two interesting results. First, it indicates that the shear viscosity is not corrected by ?? effects in this system. For flow perpendicular to the F1 strings the viscosity to entropy ratio take the usual value 1/4?, but for flow parallel to the F1s it vanishes as T2 at low temperature. Secondly, it encodes singularities in correlation functions coming from low-frequency modes at a finite value of the momentum along the T4 directions. This may provide a strong coupling analogue of finite density condensed matter systems for which fermionic constituents of larger operators contribute so-called ?2kF? singularities. In the NS5/F1 example, stretched strings on the gravity side play the role of these composite operators. We explore the analogue for our system of the Luttinger relation between charge density and the volume bounded by these singular surfaces. This model provides a clean example where the string-theoretic UV completion of the gravity dual to a finite density field theory plays a significant and calculable role.
A Generic Solver for Unconstrained Control Problems with Integral Functional Objectives

We present a generic solver for unconstrained control problems (UCPs) whose objectives take the form of an integral functional of the controllers. The solver generalizes and improves upon the algorithm in [1] for the Witsenhausen’s counterexample, which provides the best-known results. In essence, we show that minimizing the objective implies minimizing the marginal cost functions almost everywhere, and we perform the latter task pointwisely by the adaptive minimization technique, which speeds up the computation. We implement single-threaded and parallelized versions of the proposed algorithm. Our implementation runs 30× faster than the algorithm in [1] on the Witsenhausen’s counterexample, and we demonstrate the applicability of the solver and discuss the possible generalization to constrained problems and multidimensional controllers through three more examples.
Chemistry Along Accretion Streams in a Viscously Evolving Protoplanetary Disk

The composition of a protoplanetary disk is set by a combination of interstellar inheritance and gas and grain surface chemical reactions within the disk. The survival of inherited molecules, as well as the disk in situ chemistry depends on the local temperature, density and irradiation environment, which can change over time due to stellar and disk evolution, as well as transport in the disk. We address one aspect of this coupling between the physical and chemical evolution in disks by following accretion streamlines of gas and small grains in the disk midplane, while simultaneously taking the evolving star into account. This approach is computationally efficient and enables us to take into account changing physical conditions without reducing the chemical network. We find that many species are enhanced in the inner disk midplane in the dynamic model due to inward transport of cosmic-ray driven chemical products, resulting in, e.g., orders-of magnitude hydrocarbon enhancements at 1 au, compared to a static disk. For several other chemical families, there is no difference between the static and dynamic models, indicative of a robust chemical reset, while yet others show differences between static and dynamic models that depend on complex interactions between physics and chemistry during the inward track. The importance of coupling dynamics and chemistry when modeling the chemical evolution of protoplanetary disks is thus depends on what chemistry is of interest.
Nonconcentration of energy for a semilinear Skyrme model

Abstract We continue our investigation [1] of a model introduced by Adkins and Nappi [2] , in which ω mesons stabilize chiral solitons. The aim of this article is to show that the energy associated to equivariant solutions does not concentrate.
Normal-Metal Hot-Electron Nanobolometer With Johnson Noise Thermometry Readout

The sensitivity of a THz hot-electron nanobolometer (nano-HEB) made from a normal metal is analyzed. Johnson Noise Thermometry (JNT) is employed as a readout technique. In contrast to its superconducting Transition-Edge Sensor (TES) counterpart, the normal-metal nano-HEB can operate at any cryogenic temperature depending on the required radiation background limited Noise Equivalent Power (NEP). It does not require bias lines; 100s of nano-HEBs can be read by a single low-noise $X$ -band amplifier via a filter bank channelizer. The modeling predicts that even with the sensitivity penalty due to the amplifier noise, an ${\rm NEP}{\sim} 10^{-20}{\hbox{--}}10^{-19}{\hbox{W/Hz}}^{1/2}$ can be expected at 50–100 mK in 10–20 nm thin titanium (Ti) normal metal HEBs with niobium (Nb) contacts. This NEP is fairly constant over a range of readout frequencies $\sim$ 10 GHz. Although materials with weaker electron-phonon coupling (bismuth, graphene) do not improve the minimum achievable NEP, they can be considered if a larger than 10 GHz readout bandwidth is required.
Curved A_{\infty }-algebras and gauge theory

We propose a general notion of algebraic gauge theory obtained via extracting the main properties of classical gauge theory. Building on a recent work on transferring curved \(A_{\infty }\)-structures we show that, under certain technical conditions, algebraic gauge theories can be transferred along chain contractions. Specializing to the case of the contraction from differential forms to cochains, we obtain a simplicial gauge theory on the matrix-valued simplicial cochains of a triangulated manifold. In particular, one obtains discrete notions of connection, curvature, gauge transformation and gauge invariant action.
THE EFFECT OF PLANETS BEYOND THE ICE LINE ON THE ACCRETION OF VOLATILES BY HABITABLE-ZONE ROCKY PLANETS

Models of planet formation have shown that giant planets have a large impact on the number, masses, and orbits of terrestrial planets that form. In addition, they play an important role in delivering volatiles from material that formed exterior to the snow line (the region in the disk beyond which water ice can condense) to the inner region of the disk where terrestrial planets can maintain liquid water on their surfaces. We present simulations of the late stages of terrestrial planet formation from a disk of protoplanets around a solar-type star and we include a massive planet (from 1 M {sub ⊕} to 1 M {sub J}) in Jupiter's orbit at ∼5.2 AU in all but one set of simulations. Two initial disk models are examined with the same mass distribution and total initial water content, but with different distributions of water content. We compare the accretion rates and final water mass fraction of the planets that form. Remarkably, all of the planets that formed in our simulations without giant planets were water-rich, showing that giant planet companions are not required to deliver volatiles to terrestrial planets in the habitable zone. In contrast, an outer planet at least several timesmore » the mass of Earth may be needed to clear distant regions of debris truncating the epoch of frequent large impacts. Observations of exoplanets from radial velocity surveys suggest that outer Jupiter-like planets may be scarce, therefore, the results presented here suggest that there may be more habitable planets residing in our galaxy than previously thought.« less
Characterization of the Mid-Frequency Arrays for Advanced ACTPol

The Advanced ACTPol upgrade on the Atacama Cosmology Telescope aims to improve the measurement of the cosmic microwave background anisotropies and polarization, using four new dichroic detector arrays fabricated on 150-mm silicon wafers. These bolometric cameras use AlMn transition-edge sensors, coupled to feedhorns with orthomode transducers for polarization sensitivity. The first deployed camera is sensitive to both 150 and 230 GHz. Here, we present the laboratory characterization of the thermal parameters and optical efficiencies for the two newest fielded arrays, each sensitive to both 90 and 150 GHz. We provide assessments of the parameter uniformity across each array with evaluation of systematic uncertainties. Lastly, we show the arrays’ initial performance in the field.
AN INVESTIGATION INTO THE CHARACTER OF PRE-EXPLOSION CORE-COLLAPSE SUPERNOVA SHOCK MOTION

We investigate the structure of the stalled supernova shock in both two and three dimensions (2D and 3D, respectively) and explore the differences in the effects of neutrino heating and the standing accretion shock instability (SASI). We find that early on the amplitude of the dipolar mode of the shock is factors of {approx}2-3 smaller in 3D than in 2D. However, later in both 3D and 2D, the monopole and dipole modes start to grow until explosion. Whereas in 2D, the (l, m) = (1, 0) mode changes sign quasi-periodically, producing the 'up-and-down' motion always seen in modern 2D simulations, in 3D this almost never happens. Rather, in 3D when the dipolar mode starts to grow, it grows in magnitude and wanders stochastically in direction until settling before explosion to a particular patch of solid angle. Furthermore, in 2D, we find that the amplitude of the dipolar shock deformation separates into two classes. For the first, identified with the SASI and for a wide range of 'low' neutrino luminosities, this amplitude remains small and roughly constant. For the other, identified with higher luminosities and neutrino-driven convection, the dipolar amplitude grows sharply. Importantly, it is only for this higher luminosity classmore » that we see neutrino-driven explosions within {approx}1 s of bounce. Moreover, for the 'low' luminosity runs (including zero), the power spectra of these dipolar oscillations peak in the 30-50 Hz range associated with advection timescales, while for the high-luminosity runs the power spectra at lower frequencies are significantly more prominent. We associate this enhanced power at lower frequencies with slower convective effects and the secular growth of the dipolar shock amplitude. Though our study involves a simplified, parameterized approach, on the basis of it we hypothesize that neutrino-driven buoyant convection should almost always dominate the SASI when the supernova explosion is neutrino-driven.« less
Atmospheric Neutrino Fluxes

Starting with a historical review, I summarize the status of calculations of the flux of atmospheric neutrinos and how they compare to the measurements.
IMPROVED SPECTROPHOTOMETRIC CALIBRATION OF THE SDSS-III BOSS QUASAR SAMPLE

We present a model for spectrophotometric calibration errors in observations of quasars from the third generation of the Sloan Digital Sky Survey Baryon Oscillation Spectroscopic Survey (BOSS) and describe the correction procedure we have developed and applied to this sample. Calibration errors are primarily due to atmospheric differential refraction and guiding offsets during each exposure. The corrections potentially reduce the systematics for any studies of BOSS quasars, including the measurement of baryon acoustic oscillations using the Ly? forest. Our model suggests that, on average, the observed quasar flux in BOSS is overestimated by ~19% at 3600 ? and underestimated by ~24% at 10,000 ?. Our corrections for the entire BOSS quasar sample are publicly available.
Two New Ejecta-dominated Galactic Supernova Remnants: G337.2–0.7 and G309.2–0.6

We present the analysis of new X-ray observations of two Galactic radio supernova remnants (SNRs), G337.2-0.7 and G309.2-0.6. Both remnants exhibit line-rich thermal spectra that require highly nonsolar elemental abundance ratios. In each case, Si and S are unequivocally overabundant compared to solar, based purely on the measured equivalent width of the Kα line complex. Detailed nonequilibrium ionization spectral analysis of these remnants, using a single-temperature, single ionization age model, confirms the overabundances, yielding Si, S, and Ar abundances many times their solar values: 3-5 times solar for G337.2-0.7 and greater than 3-10 times solar for G309.2-0.6. We also find that for both remnants, Ne and Mg are underabundant relative to Si, and for G309.2-0.6, Ca and Fe are relatively underabundant as well. This is the first detection of metal-rich, nonsolar abundance material in these remnants, identifying them as young ejecta-dominated SNRs. Further support for their youth comes from the distances that we estimate from the fitted column densities (less than 15 kpc for G337.2-0.7, and 4 ± 2 kpc for G309.2-0.6). From the implied sizes of the remnants at these distances we infer relatively young ages (2000-4500 years for G337.2-0.7 and 700-4000 years for G309.2-0.6). Finally, we note that no compact object has yet been found within G337.2-0.7, but an X-ray point source is evident within the radio shell of G309.2-0.6, although its nature remains unknown.
The polytope of Tesler matrices

We introduce the Tesler polytope $$\mathsf {Tes}_n(\mathbf{a})$$ , whose integer points are the Tesler matrices of size n with hook sums $$a_1,a_2,\ldots ,a_n \in \mathbb {Z}_{\ge 0}$$ . We show that $$\mathsf {Tes}_n(\mathbf{a})$$ is a flow polytope and therefore the number of Tesler matrices is counted by the type $$A_n$$ Kostant partition function evaluated at $$(a_1,a_2,\ldots ,a_n,-\sum _{i=1}^n a_i)$$ . We describe the faces of this polytope in terms of “Tesler tableaux” and characterize when the polytope is simple. We prove that the h-vector of $$\mathsf {Tes}_n(\mathbf{a})$$ when all $$a_i>0$$ is given by the Mahonian numbers and calculate the volume of $$\mathsf {Tes}_n(1,1,\ldots ,1)$$ to be a product of consecutive Catalan numbers multiplied by the number of standard Young tableaux of staircase shape.
Testing the Radiation Pattern of Meteor Radio Afterglow

Radio emission from meteors or meteor radio afterglows (MRAs) were first detected using the all-sky imaging capabilities of the first station of the Long Wavelength Array (LWA1). In this work, we use the recently commissioned LWA Sevilleta (LWA-SV) station along with the LWA1 to carry out co-ordinated observations. The combined all-sky observations with LWA1 and LWA-SV have co-observed 32 MRAs and 21 transmitter reflections from meteors (meteor scatter events) which are believed to be specular reflections from overdense trails. The flux density of the events observed by each station were measured from the all-sky images. Triangulating the angular direction of events from each station gave the physical location and the distance of the event to each station. The luminosity of the events in each station were calculated using the flux distance relation for an isotropic source. The luminosity distribution for MRAs and meteor scatter events observed by each station shows a clear distinction between these two types of events as the ratio of luminosities are closer to unity for MRAs than the meteor scatter events. Furthermore, we find that MRAs follow an isotropic radiation pattern. This suggests, either a complete incoherent emission mechanism or an incoherent addition of coherently emitting small regions within the meteor trail.
Distance one lens space fillings and band surgery on the trefoil knot

We prove that if the lens space L(n,1) is obtained by a surgery along a knot in the lens space L(3,1) that is distance one from the meridional slope, then n is in {−6,±1,±2,3,4,7}. This result yields a classification of the coherent and noncoherent band surgeries from the trefoil to T(2,n) torus knots and links. The main result is proved by studying the behavior of the Heegaard Floer d–invariants under integral surgery along knots in L(3,1). The classification of band surgeries between the trefoil and torus knots and links is motivated by local reconnection processes in nature, which are modeled as band surgeries. Of particular interest is the study of recombination on circular DNA molecules.
In-flight calibration of the Chandra high-energy transmission grating spectrometer

We present results from in-flight calibration of the High Energy Transmission Grating Spectrometer (HETGS) on the Chandra X-ray Observatory. Basic grating assembly parameters such as orientation and average grating period were measured using emission line sources. These sources were also used to determine the locations of individual CCDs within the flight detector. The line response function (LRF) was modeled in detail using an instrument simulator based on pre-flight measurements of the grating alignments and periods. These LRF predictions agree very well with in-flight observations of sources with narrow emission lines. Using bright continuum sources, we test the consistency of the detector quantum efficiencies by comparing positive orders to negative orders.
Chimera states: Coexistence of coherence and incoherence in networks of coupled oscillators

A chimera state is a spatio-temporal pattern in a network of identical coupled oscillators in which synchronous and asynchronous oscillation coexist. This state of broken symmetry, which usually coexists with a stable spatially symmetric state, has intrigued the nonlinear dynamics community since its discovery in the early 2000s. Recent experiments have led to increasing interest in the origin and dynamics of these states. Here we review the history of research on chimera states and highlight major advances in understanding their behaviour.
Exoplanet Atmosphere Measurements from Transmission Spectroscopy and Other Planet Star Combined Light Observations

It is possible to learn a great deal about exoplanet atmospheres even when we cannot spatially resolve the planets from their host stars. In this chapter, we overview the basic techniques used to characterize transiting exoplanets - transmission spectroscopy, emission and reflection spectroscopy, and full-orbit phase curve observations. We discuss practical considerations, including current and future observing facilities and best practices for measuring precise spectra. We also highlight major observational results on the chemistry, climate, and cloud properties of exoplanets.
The gap of the area-weighted Motzkin spin chain is exponentially small

We prove that the energy gap of the model proposed by Zhang, Ahmadain, and Klich [1] is exponentially small in the square of the system size. In [2] a class of exactly solvable quantum spin chain models was proposed that have integer spins ($s$), with a nearest neighbors Hamiltonian, and a unique ground state. The ground state can be seen as a uniform superposition of all $s-$colored Motzkin walks. The half-chain entanglement entropy provably violates the area law by a square root factor in the system's size ($\sim\sqrt{n}$) for $s>1$. For $s=1$, the violation is logarithmic [3]. Moreover in [2] it was proved that the gap vanishes polynomially and is $O(n^{-c})$ with $c\ge2$. Recently, a deformation of [2], which we call "weighted Motzkin quantum spin chain" was proposed [1]. This model has a unique ground state that is a superposition of the $s-$colored Motzkin walks weighted by $t^{\text{area\{Motzkin walk\}}}$ with $t>1$. The most surprising feature of this model is that it violates the area law by a factor of $n$. Here we prove that the gap of this model is upper bounded by $8ns\text{ }t^{-n^{2}/3}$ for $t>1$.
Improved homological stability for configuration spaces after inverting 2

In Appendix A of his article on rational functions, Segal proved homological stability for configuration spaces with a stability slope of 1/2. This was later improved to a slope of 1 by Church and Randal-Williams if one works with rational coefficients and manifolds of dimension at least $3$. In this note we prove that the stability slope of 1 holds even with Z[1/2] coefficients, and clarify some aspects of Segal's proof for topological manifolds.