cssi/SciSciGPT-SciSciNet huggingface dataset:
Optimizing the robustness of electrical power systems against cascading failures

Electrical power systems are one of the most important infrastructures that support our society. However, their vulnerabilities have raised great concern recently due to several large-scale blackouts around the world. In this paper, we investigate the robustness of power systems against cascading failures initiated by a random attack. This is done under a simple yet useful model based on global and equal redistribution of load upon failures. We provide a comprehensive understanding of system robustness under this model by (i) deriving an expression for the final system size as a function of the size of initial attacks; (ii) deriving the critical attack size after which system breaks down completely; (iii) showing that complete system breakdown takes place through a first-order (i.e., discontinuous) transition in terms of the attack size; and (iv) establishing the optimal load-capacity distribution that maximizes robustness. In particular, we show that robustness is maximized when the difference between the capacity and initial load is the same for all lines; i.e., when all lines have the same redundant space regardless of their initial load. This is in contrast with the intuitive and commonly used setting where capacity of a line is a fixed factor of its initial load.
Probing the Mysteries of the X-Ray Binary 4U 1210-64 with ASM, PCA, MAXI, BAT, and Suzaku

4U 1210-64 has been postulated to be a high-mass X-ray binary powered by the Be mechanism. X-ray observations with Suzaku, the ISS Monitor of All-sky X-ray Image (MAXI), and the Rossi X-ray Timing Explorer Proportional Counter Array (PCA) and All Sky Monitor (ASM) provide detailed temporal and spectral information on this poorly understood source. Long-term ASM and MAXI observations show distinct high and low states and the presence of a 6.7101 +/- 0.0005 day modulation, interpreted as the orbital period. Folded light curves reveal a sharp dip, interpreted as an eclipse. To determine the nature of the mass donor, the predicted eclipse half-angle was calculated as a function of inclination angle for several stellar spectral types. The eclipse half-angle is not consistent with a mass donor of spectral type B5 V; however, stars with spectral types B0 V or B0-5 III are possible. The best-fit spectral model consists of a power law with index gamma = 1.85(+0.04/0.05) and a high-energy cutoff at 5.5 +/- 0.2 keV modified by an absorber that fully covers the source as well as partially covering absorption. Emission lines from S XVI K alpha, Fe K alpha, Fe XXV K alpha, and Fe XXVI K alpha were observed in the Suzaku spectra. Out of eclipse, the Fe K alpha line flux was strongly correlated with unabsorbed continuum flux, indicating that the Fe I emission is the result of fluorescence of cold dense material near the compact object. The Fe I feature is not detected during eclipse, further supporting an origin close to the compact object.
Quasars Probing Quasars. IX. The Kinematics of the Circumgalactic Medium Surrounding z ∼ 2 Quasars

We examine the kinematics of the gas in the environments of galaxies hosting quasars at $z\sim2$. We employ 148 projected quasar pairs to study the circumgalactic gas of the foreground quasars in absorption. The sample selects foreground quasars with precise redshift measurements, using emission-lines with precision $\lesssim300\,{\rm km\,s^{-1}}$ and average offsets from the systemic redshift $\lesssim|100\,{\rm km\,s^{-1}}|$. We stack the background quasar spectra at the foreground quasar's systemic redshift to study the mean absorption in \ion{C}{2}, \ion{C}{4}, and \ion{Mg}{2}. We find that the mean absorptions exhibit large velocity widths $\sigma_v\approx300\,{\rm km\,s^{-1}}$. Further, the mean absorptions appear to be asymmetric about the systemic redshifts. The mean absorption centroids exhibit small redshift relative to the systemic $\delta v\approx+200\,{\rm km\,s^{-1}}$, with large intrinsic scatter in the centroid velocities of the individual absorption systems. We find the observed widths are consistent with gas in gravitational motion and Hubble flow. However, while the observation of large widths alone does not require galactic-scale outflows, the observed offsets suggest that the gas is on average outflowing from the galaxy. The observed offsets also suggest that the ionizing radiation from the foreground quasars is anisotropic and/or intermittent.
Some Thermodynamic Aspects of Black Holes and Singularities

We review and correct the classical critical exponents characterizing the transition from negative to positive black hole's heat capacity at high charge-angular momentum. We discuss the stability properties of black holes as a thermodynamic system in equilibrium with a radiation bath (canonical ensemble) by using the Helmholtz free energy potential. Finally we analytically extend the analysis to any value of the variables in the Helmholtz potential and show that this leads to the consideration of negative mass holes. We then study their curious thermodynamical stability behavior.
On uniqueness of solutions to conservation laws verifying a single entropy condition

For hyperbolic systems of conservation laws, uniqueness of solutions is still largely open. We aim to expand the theory of uniqueness for systems of conservation laws. One difficulty is that many s...
Gauge theory of Faddeev-Skyrme functionals

We study geometric variational problems for a class of nonlinear σ-models in quantum field theory. Mathematically, one needs to minimize an energy functional on homotopy classes of maps from closed 3-manifolds into compact homogeneous spaces G/H. The minimizers are known as Hopfions and exhibit localized knot-like structure. Our main results include proving existence of Hopfions as finite energy Sobolev maps in each (generalized) homotopy class when the target space is a symmetric space. For more general spaces, we obtain a weaker result on existence of minimizers in each 2-homotopy class. Our approach is based on representing maps into G/H by equivalence classes of flat connections. The equivalence is given by gauge symmetry on pullbacks of G → G/H bundles. We work out a gauge calculus for connections under this symmetry, and use it to eliminate non-compactness from the minimization problem by fixing the gauge.
Assessments of Ali, Dome A, and Summit Camp for mm-wave Observations Using MERRA-2 Reanalysis

NASA's latest MERRA-2 reanalysis of the modern satellite measurements has made atmospheric data easily accessible with unprecedented uniformity, fidelity, and completeness. In this paper, these data are used to evaluate five sites for millimeter-wave (mm-wave) observations. These include two established sites (South Pole and Chajnantor, Atacama), and three new sites (Ali in Tibet, Dome A in Antarctica, and Summit Camp in Greenland). Atmospheric properties including precipitable water vapor (PWV), sky brightness temperature fluctuations, and ice and liquid water paths are derived and compared. Dome A emerges to be the best among those evaluated, with PWV and fluctuations smaller than the second-best site, South Pole, by more than a factor of 2. It is found that the higher site in Ali (6100 m) is on par with Cerro Chajnantor (5612 m) in terms of transmission and stability. The lower site in Ali (5250 m) planned for the first stage of observations at 90/150 GHz provides conditions comparable to those on the Chajnantor Plateau. These analyses confirm Ali to be an excellent mm-wave site in the Northern Hemisphere that will complement well-established Southern sites. According to MERRA-2 data, the observing conditions at Summit Camp are also comparable to Cerro Chajnantor. However, it is more affected by the presence of liquid water clouds.
Polynomials with no zeros on the bidisk

We prove a detailed sums of squares formula for two-variable polynomials with no zeros on the bidisk D2, extending previous such formulas by Cole and Wermer and by Geronimo and Woerdeman. Our formula is related to the Christoffel–Darboux formula for orthogonal polynomials on the unit circle, but the extension to two variables involves issues of uniqueness in the formula and the study of ideals of two-variable orthogonal polynomials with respect to a positive Borel measure on the torus which may have infinite mass. We present applications to two-variable Fejer–Riesz factorizations, analytic extension theorems for a class of bordered curves called distinguished varieties, and Pick interpolation on the bidisk.
Surface Passivation in Empirical Tight Binding

Empirical tight binding (TB) methods are widely used in atomistic device simulations. Existing TB methods to passivate dangling bonds fall into two categories: 1) method that explicitly includes passivation atoms is limited to passivation with atoms and small molecules only and 2) method that implicitly incorporates passivation does not distinguish passivation atom types. This paper introduces an implicit passivation method that is applicable to any passivation scenario with appropriate parameters. This method is applied to a Si quantum well and a Si ultrathin body transistor oxidized with SiO2 in several oxidation configurations. Comparison with ab ini t io results and experiments verifies the presented method. Oxidation configurations that severely hamper the transistor performance are identified. It is also shown that the commonly used implicit H atom passivation overestimates the transistor performance.
Internal wave boluses as coherent structures in a continuously stratified fluid

Internal waves shoaling on the continental slope can break and form materially coherent vortices called boluses. These boluses are able to trap and transport material up the continental slope, yet the global extent of bolus transport is unknown. Previous studies of bolus formation primarily focused on systems consisting of two layers of uniform density, which do not account for the presence of ocean pycnoclines of finite thickness. We use hyperbolic tangent profiles to model the density stratification in our simulations and demonstrate the impact of the pycnocline on the bolus. A spectral clustering method is used to objectively identify the bolus as a Lagrangian coherent structure that contains the material advected upslope. The bolus size and displacement upslope are examined as a function of the pycnocline thickness, incoming wave energy, density change across the pycnocline and topographic slope. The dependence of bolus transport on the pycnocline thickness demonstrates that boluses in continuous stratifications tend to be larger and transport material further than in corresponding two-layer stratifications.
Adaptive Output Feedback Based on Closed-Loop Reference Models

This technical note presents the design and analysis of an adaptive controller for a class of linear plants in the presence of output feedback. This controller makes use of a closed-loop reference model as an observer, and guarantees global stability and asymptotic output tracking.
THE GINI COEFFICIENT AS A TOOL FOR IMAGE FAMILY IDENITIFICATION IN STRONG LENSING SYSTEMS WITH MULTIPLE IMAGES

The sample of cosmological strong lensing systems has been steadily growing in recent years and with the advent of the next generation of space-based survey telescopes, the sample will reach into the thousands. The accuracy of strong lens models relies on robust identification of multiple image families of lensed galaxies. For the most massive lenses, often more than one background galaxy is magnified and multiply imaged, and even in the cases of only a single lensed source, identification of counter images is not always robust. Recently, we have shown that the Gini coefficient in space-telescope-quality imaging is a measurement of galaxy morphology that is relatively well-preserved by strong gravitational lensing. Here, we investigate its usefulness as a diagnostic for the purposes of image family identification and show that it can remove some of the degeneracies encountered when using color as the sole diagnostic, and can do so without the need for additional observations since whenever a color is available, two Gini coefficients are as well.
Single-particle and collective excitations in quantum wires made up of vertically stacked quantum dots: Zero magnetic field

We report on the theoretical investigation of the elementary electronic excitations in a quantum wire made up of vertically stacked self-assembled InAs/GaAs quantum dots. The length scales (of a few nanometers) involved in the experimental setups prompt us to consider an infinitely periodic system of two-dimensionally confined (InAs) quantum dot layers separated by GaAs spacers. The resultant quantum wire is characterized by a two-dimensional harmonic confining potential in the x-y plane and a periodic (Kronig-Penney) potential along the z (or the growth) direction within the tight-binding approximation. Since the wells and barriers are formed from two different materials, we employ the Bastard's boundary conditions in order to determine the eigenfunctions along the z direction. These wave functions are then used to generate the Wannier functions, which, in turn, constitute the legitimate Bloch functions that govern the electron dynamics along the direction of periodicity. Thus, the Bloch functions and th...
Certain inequalities involving prolate spheroidal wave functions and associated quantities

Abstract Prolate spheroidal wave functions (PSWFs) play an important role in various areas, from physics (e.g. wave phenomena, fluid dynamics) to engineering (e.g. signal processing, filter design). Even though the significance of PSWFs was realized at least half a century ago, and they frequently occur in applications, their analytical properties have not been investigated as much as those of many other special functions. In particular, despite some recent progress, the gap between asymptotic expansions and numerical experience, on the one hand, and rigorously proven explicit bounds and estimates, on the other hand, is still rather wide. This paper attempts to improve the current situation. We analyze the differential operator associated with PSWFs, to derive fairly tight estimates on its eigenvalues. By combining these inequalities with a number of standard techniques, we also obtain several other properties of the PSFWs. The results are illustrated via numerical experiments.
Primary beam steering due to field leakage from superconducting SHMS magnets

Simulations of the magnetic fields from the Super High Momentum Spectrometer in Hall C at Thomas Jefferson National Accelerator Facility show significant field leakage into the region of the primary beam line between the target and the beam dump. Without mitigation, these remnant fields will steer the unscattered beam enough to limit beam operations at small scattering angles. Presented here are magnetic field simulations of the spectrometer magnets and a solution using optimal placement of a minimal amount of shielding iron around the beam line.
Revec: program rejuvenation through revectorization

Modern microprocessors are equipped with Single Instruction Multiple Data (SIMD) or vector instructions which expose data level parallelism at a fine granularity. Programmers exploit this parallelism by using low-level vector intrinsics in their code. However, once programs are written using vector intrinsics of a specific instruction set, the code becomes non-portable. Modern compilers are unable to analyze and retarget the code to newer vector instruction sets. Hence, programmers have to manually rewrite the same code using vector intrinsics of a newer generation to exploit higher data widths and capabilities of new instruction sets. This process is tedious, error-prone and requires maintaining multiple code bases. We propose Revec, a compiler optimization pass which revectorizes already vectorized code, by retargeting it to use vector instructions of newer generations. The transformation is transparent, happening at the compiler intermediate representation level, and enables performance portability of hand-vectorized code. Revec can achieve performance improvements in real-world performance critical kernels. In particular, Revec achieves geometric mean speedups of 1.160× and 1.430× on fast integer unpacking kernels, and speedups of 1.145× and 1.195× on hand-vectorized x265 media codec kernels when retargeting their SSE-series implementations to use AVX2 and AVX-512 vector instructions respectively. We also extensively test Revec’s impact on 216 intrinsic-rich implementations of image processing and stencil kernels relative to hand-retargeting.
Involution words II: braid relations and atomic structures

Involution words are variations of reduced words for twisted involutions in Coxeter groups. They arise naturally in the study of the Bruhat order, of certain Iwahori---Hecke algebra modules, and of orbit closures in flag varieties. Specifically, to any twisted involutions x, y in a Coxeter group W with automorphism $$*$$ź, we associate a set of involution words $$\hat{\mathcal {R}}_*(x,y)$$R^ź(x,y). This set is the disjoint union of the reduced words of a set of group elements $$\mathcal {A}_*(x,y)$$Aź(x,y), which we call the atoms of y relative to x. The atoms, in turn, are contained in a larger set $$\mathcal {B}_*(x,y) \subset W$$Bź(x,y)źW with a similar definition, whose elements are referred to as Hecke atoms. Our main results concern some interesting properties of the sets $$\hat{\mathcal {R}}_*(x,y)$$R^ź(x,y) and $$\mathcal {A}_*(x,y) \subset \mathcal {B}_*(x,y)$$Aź(x,y)źBź(x,y). For finite Coxeter groups, we prove that $$\mathcal {A}_*(1,y)$$Aź(1,y) consists of exactly the minimal-length elements $$w \in W$$wźW such that $$w^* y \le w$$wźy≤w in Bruhat order, and we conjecture a more general property for arbitrary Coxeter groups. In type A, we describe a simple set of conditions characterizing the sets $$\mathcal {A}_*(x,y)$$Aź(x,y) for all involutions $$x,y \in S_n$$x,yźSn, giving a common generalization of three recent theorems of Can et al. We show that the atoms of a fixed involution in the symmetric group (relative to $$x=1$$x=1) naturally form a graded poset, while the Hecke atoms surprisingly form an equivalence class under the "Chinese relation" studied by Cassaigne et al. These facts allow us to recover a recent theorem of Hu and Zhang describing a set of "braid relations" spanning the involution words of any self-inverse permutation. We prove a generalization of this result giving an analogue of Matsumoto's theorem for involution words in arbitrary Coxeter groups.
Helix: accelerating human-in-the-loop machine learning

Data application developers and data scientists spend an inordinate amount of time iterating on machine learning (ML) workflows---by modifying the data pre-processing, model training, and postprocessing steps---via trial-and-error to achieve the desired model performance. Existing work on accelerating machine learning focuses on speeding up one-shot execution of workflows, failing to address the incremental and dynamic nature of typical ML development. We propose Helix, a declarative machine learning system that accelerates iterative development by optimizing workflow execution end-to-end and across iterations. Helix minimizes the runtime per iteration via program analysis and intelligent reuse of previous results, which are selectively materialized---trading off the cost of materialization for potential future benefits---to speed up future iterations. Additionally, Helix offers a graphical interface to visualize workflow DAGs and compare versions to facilitate iterative development. Through two ML applications, in classification and in structured prediction, attendees will experience the succinctness of Helix's programming interface and the speed and ease of iterative development using Helix. In our evaluations, Helix achieved up to an order of magnitude reduction in cumulative run time compared to state-of-the-art machine learning tools.
InGaN/GaN tunnel junctions for hole injection in GaN light emitting diodes

InGaN/GaN tunnel junction contacts were grown using plasma assisted molecular beam epitaxy (MBE) on top of a metal-organic chemical vapor deposition (MOCVD)-grown InGaN/GaN blue (450 nm) light emitting diode. A voltage drop of 5.3 V at 100 mA, forward resistance of 2 × 10−2 Ω cm2, and a higher light output power compared to the reference light emitting diodes (LED) with semi-transparent p-contacts were measured in the tunnel junction LED (TJLED). A forward resistance of 5 × 10−4 Ω cm2 was measured in a GaN PN junction with the identical tunnel junction contact as the TJLED, grown completely by MBE. The depletion region due to the impurities at the regrowth interface between the MBE tunnel junction and the MOCVD-grown LED was hence found to limit the forward resistance measured in the TJLED.
Hidden Double-peaked Emitters in Seyfert 2 Galaxies

We present the detection of extremely broad, double-peaked, highly polarized Hα emission lines in the nuclei of the well-known Seyfert 2 galaxies NGC 2110 and NGC 5252. These hidden broad Hα emission lines, visible only in scattered light, are shown to display significant variability in strength and profile on timescales of 1 yr. That the broad emission line exhibits variability in polarized flux also suggests that the scattering region must be very compact, possibly confined in a small number of electron clouds 1 lt-yr in size. Our observational constraints place these clouds within ~10 pc of the nucleus with temperatures Te 106 K and densities ne ~ 107 cm–3, consistent with a region just outside the obscuring torus between the broad-line region and narrow-line region. These scattering clouds could arise from the clumpy torus itself. These findings and other properties indicate that NGC 2110 and NGC 5252 are the hidden counterparts to the broad-line double-peaked emission-line active galactic nuclei, whose examples include Arp 102B and 3C 332.
Molecular Disk Properties in Early Type Galaxies

We study the simulated CO emission from elliptical galaxies formed in the mergers of gas-rich disk galaxies. The cold gas not consumed in the merger-driven starburst quickly resettles into a disk-like configuration. By analyzing a variety of arbitrary merger orbits that produce a range of fast- to slow-rotating remnants, we find that molecular disk formation is a fairly common consequence of gas-rich galaxy mergers. Hence, if a molecular disk is observed in an early-type merger remnant, it is likely the result of a wet merger rather than a dry merger. We compare the physical properties from our simulated disks (e.g., size and mass) and find reasonably good agreement with recent observations. Finally, we discuss the detectability of these disks as an aid to future observations.
Narrative Text Generation with a Latent Discrete Plan

Past work on story generation has demonstrated the usefulness of conditioning on a generation plan to generate coherent stories. However, these approaches have used heuristics or off-the-shelf models to first tag training stories with the desired type of plan, and then train generation models in a supervised fashion. In this paper, we propose a deep latent variable model that first samples a sequence of anchor words, one per sentence in the story, as part of its generative process. During training, our model treats the sequence of anchor words as a latent variable and attempts to induce anchoring sequences that help guide generation in an unsupervised fashion. We conduct experiments with several types of sentence decoder distributions – left-to-right and non-monotonic, with different degrees of restriction. Further, since we use amortized variational inference to train our model, we introduce two corresponding types of inference network for predicting the posterior on anchor words. We conduct human evaluations which demonstrate that the stories produced by our model are rated better in comparison with baselines which do not consider story plans, and are similar or better in quality relative to baselines which use external supervision for plans. Additionally, the proposed model gets favorable scores when evaluated on perplexity, diversity, and control of story via discrete plan
REALITY CONDITIONS FOR LORENTZIAN AND EUCLIDEAN GRAVITY IN THE ASHTEKAR FORMULATION

Using Ashtekar variables, we analyze Lorentzian and Euclidean gravity in vacuum up to a constant conformal transformation. Keeping unaltered the symplectic structure in the full theory of complex gravity, we prove that the reality conditions are invariant under a Wick rotation of the time, and show that the compatibility of the algebra of commutators and constraints with the involution defined by the reality conditions restricts the possible values of the conformal factor to be either real or purely imaginary. In the first case, one recovers real Lorentzian general relativity. For purely imaginary conformal factors, the classical theory can be interpreted as real Euclidean gravity. The reality conditions associated with this Euclidean theory demand the hermiticity of the Ashtekar connection, but the densitized triad is represented by an anti-Hermitian operator. We also demonstrate that the Euclidean and Lorentzian sets of reality conditions lead to inequivalent quantizations of full general relativity. This conclusion also holds in the geometrodynamic formulation. As a consequence, it seems impossible to obtain Lorentzian physical predictions from the quantum theory constructed with the Euclidean reality conditions.
CONSTANT MEAN CURVATURE, FLUX CONSERVATION, AND SYMMETRY

As first noted by Korevaar, Kusner, and Solomon, constant mean curvature implies a homological conservation law for hypersurfaces in ambient spaces with Killing fields. We generalize that law by relaxing the topological restrictions assumed by Korevaar et al., and by allowing a weighted mean curvature functional. We also prove a partial converse, which roughly says that when flux is conserved along a Killing field, a hypersurface splits into two regions: one with constant (weighted) mean curvature, and one preserved by the Killing field. We demonstrate our theory by using it to derive a first integral for helicoidal surfaces of constant mean curvature in R 3 , i.e., “twizzlers”.
Regularity bounds for twisted commutative algebras

Let A be the twisted commutative algebra freely generated by d indeterminates of degree 1. We show that the regularity of an A-module can be bounded from the first floor(d^2/4) + 2 terms of its minimal free resolution. This extends results of Church and Ellenberg from the d=1 case.
CATACLYSMIC VARIABLES IN THE SUPERBLINK PROPER MOTION SURVEY

We have discovered a new high proper motion cataclysmic variable (CV) in the SUPERBLINK proper motion survey, which is sensitive to stars with proper motions greater than 40 mas yr{sup −1}. This CV was selected for follow-up observations as part of a larger search for CVs selected based on proper motions and their near-UV−V and V−K{sub s} colors. We present spectroscopic observations from the 2.4 m Hiltner Telescope at MDM Observatory. The new CV's orbital period is near 96 minutes, its spectrum shows the double-peaked Balmer emission lines characteristic of quiescent dwarf novae, and its V magnitude is near 18.2. Additionally, we present a full list of known CVs in the SUPERBLINK catalog.
Solving Witten's SFT by insertion of operators on projectors

Following Okawa, we insert operators at the boundary of regulated star algebra projectors to construct the leading order tachyon vacuum solution of open string field theory. We also calculate the energy density of the solution and the ratio between the kinetic and the cubic terms. A universal relationship between these two quantities is found. We show that for any twist invariant projector, the energy density can account for at most 68.46% of the D25-brane tension. The general results are then applied to regulated slivers and butterflies, and the next-to-leading order solution for regulated sliver states is constructed.
Group-theoretical derivation of Aharonov-Bohm phase shifts

The phase shifts of the Aharonov-Bohm effect are generally determined by means of the partial wave decomposition of the underlying Schrodinger equation. It is shown here that they readily emerge from an o(2,1) calculation of the energy levels employing an added harmonic oscillator potential which discretizes the spectrum.
Amorphous germanium as a promising anode material for sodium ion batteries: a first principle study

The abundance of sodium (Na), its low-cost, and low reduction potential provide a lucrative inexpensive, safe, and environmentally benign alternative to lithium ion batteries (LIBs). The significant challenges in advancing sodium ion battery (NIB) technologies lie in finding the better electrode materials. Experimental investigations revealed the real potency of germanium (Ge) as suitable anode materials for NIBs. However, a systematic atomistic study is necessary to understand the fundamental aspects of capacity–voltage correlation, microstructural changes of Ge, as well as diffusion kinetics. We, therefore, performed the Density Functional Theory (DFT) and Ab Initio Molecular Dynamics (AIMD) simulation to investigate the sodiation–desodiation kinetics in germanium–sodium system (Na64Ge64). We analyzed the intercalation potential and capacity correlation for intermediate equilibrium structures and compared our data with the experimental results. Effect of sodiation on inter-atomic distances within Na–Ge system is analyzed by means of Pair Correlation Function (PCF). This provides insight into possible microstructural changes taking place during sodiation of amorphous Ge (a-Ge). We further investigated the diffusivity of sodium in a-Ge electrode material and analyzed the volume expansion trend for Na64Ge64 electrode system. Our computational results provide the fundamental insight into the atomic scale and help experimentalists design Ge-based NIBs for real-life applications.
Heavy Gravitino and Split SUSY in the Light of BICEP2

High-scale supersymmetry (SUSY) with a split spectrum has become increasingly interesting given the current experimental results. A SUSY scale above the weak scale could be naturally associated with a heavy unstable gravitino, whose decays populate the dark matter (DM) particles. In the mini-split scenario with gravitino at about the PeV scale and the lightest TeV scale neutralino being (a component of) DM, the requirement that the DM relic abundance resulting from gravitino decays does not overclose the Universe and satisfies the indirect detection constraints demand the reheating temperature to be below 109 − 1010 GeV. On the other hand, the BICEP2 result prefers a heavy inflaton with mass at around 1013 GeV and a reheating temperature at or above 109 GeV with some general assumptions. The mild tension could be alleviated if SUSY scale is even higher with the gravitino mass above the PeV scale. Intriguingly, in no-scale supergravity, gravitinos could be very heavy at about 1013 GeV, the inflaton mass scale, while gauginos could still be light at the TeV scale.
Density Enhancements and Voids Following Patchy Reconnection

We show, through a simple patchy reconnection model, that retracting reconnected flux tubes may present elongated regions relatively devoid of plasma, as well as long lasting, dense central hot regions. Reconnection is assumed to happen in a small patch across a Syrovatskiiˇ (non-uniform) current sheet (CS) with skewed magnetic fields. The background magnetic pressure has its maximum at the center of the CS plane and decreases toward its edges. The reconnection patch creates two V-shaped reconnected tubes that shorten as they retract in opposite directions, due to magnetic tension. One of them moves upward toward the top edge of the CS, and the other one moves downward toward the top of the underlying arcade. Rotational discontinuities (RDs) propagate along the legs of the tubes and generate parallel supersonic flows that collide at the center of the tube. There, gas-dynamic shocks that compress and heat the plasma are launched outwardly. The descending tube moves through the bottom part of the CS where it expands laterally in response to the decreasing background magnetic pressure. This effect may decrease plasma density by 30%-50% of background levels. This tube will arrive at the top of the arcade that will slow it to a stop. Here, the perpendicular dynamics is halted, but the parallel dynamics continues along its legs; the RDs are shut down, and the gas is rarified to even lower densities. The hot post-shock regions continue evolving, determining a long lasting hot region on top of the arcade. We provide an observational method based on total emission measure and mean temperature that indicates where in the CS the tube has been reconnected.
An Improved Semidefinite Programming Hierarchy for Testing Entanglement

We present a stronger version of the Doherty–Parrilo–Spedalieri (DPS) hierarchy of approximations for the set of separable states. Unlike DPS, our hierarchy converges exactly at a finite number of rounds for any fixed input dimension. This yields an algorithm for separability testing that is singly exponential in dimension and polylogarithmic in accuracy. Our analysis makes use of tools from algebraic geometry, but our algorithm is elementary and differs from DPS only by one simple additional collection of constraints.
Cusps of Hilbert modular varieties

Motivated by a question of Hirzebruch on the possible topological types of cusp cross-sections of Hilbert modular varieties, we give a necessary and sufficient condition for a manifold M to be diffeomorphic to a cusp cross-section of a Hilbert modular variety. Specialized to Hilbert modular surfaces, this proves that every Sol 3–manifold is diffeo morphic to a cusp cross-section of a (generalized) Hilbert modular surface. We also deduce an obstruction to geometric bounding in this setting. Consequently, there exist Sol 3–manifolds that cannot arise as a cusp cross-section of a 1–cusped nonsingular Hilbert modular surface.
Reproducible and Portable Workflows for Scientific Computing and HPC in the Cloud

The increasing availability of cloud computing services for science has changed the way scientific code can be developed, deployed, and run. Many modern scientific workflows are capable of running on cloud computing resources. Consequently, there is an increasing interest in the scientific computing community in methods, tools, and implementations that enable moving an application to the cloud and simplifying the process, and decreasing the time to meaningful scientific results. In this paper, we have applied the concepts of containerization for portability and multi-cloud automated deployment with industry-standard tools to three scientific workflows. We show how our implementations provide reduced complexity to portability of both the applications themselves, and their deployment across private and public clouds. Each application has been packaged in a Docker container with its dependencies and necessary environment setup for production runs. Terraform and Ansible have been used to automate the provisioning of compute resources and the deployment of each scientific application in a Multi-VM cluster. Each application has been deployed on the AWS and Aristotle Cloud Federation platforms. Variation in data management constraints, Multi-VM MPI communication, and embarrassingly parallel instance deployments were all explored and reported on. We thus present a sample of scientific workflows that can be simplified using the tools and our proposed implementation to deploy and run in a variety of cloud environments.
Generalized Coherent States for Position-Dependent Effective Mass Systems

A generalized scheme for the construction of coherent states in the context of position-dependent effective mass systems has been presented. This formalism is based on the ladder operators and associated algebra of the system which are obtained using the concepts of supersymmetric quantum mechanics and the property of shape invariance. In order to exemplify the general results and to analyze the properties of the coherent states, several examples have been considered.
Heterogeneous trembles and model selection in the strategy frequency estimation method

The strategy frequency estimation method (Dal Bo and Frechette in Am Econ Rev 101(1):411-429, 2011; Fudenberg in Am Econ Rev 102(2):720-749, 2012) allows us to estimate the fraction of subjects playing each of a list of strategies in an infinitely repeated game. Currently, this method assumes that subjects tremble with the same probability. This paper extends this method, so that subjects’ trembles can be heterogeneous. Out of 60 ex ante plausible specifications, the selected model uses the six strategies described in Dal Bo and Frechette (2018), and allows the distribution of trembles to vary by strategy.
DIVERGENCES IN SCALAR QUANTUM FIELD THEORY: THE CAUSE AND THE CURE

Covariant scalar fields exhibit divergences when quantized in two or more spacetime dimensions: n ≥ 2. Does perturbation theory, effective theories, the renormalization group, etc., tell us all there is to know about these problems? An alternative approach identifies the cause of divergences as due to the effort to multiplicatively relate two measures that are mutually singular, while the cure for those divergences is to introduce an O(ℏ) counterterm that converts mutually singular measures into equivalent measures. This procedure leads to a nontrivial, divergence-free formulation for all n≥2. Finally, a critical comparison of the new methods with traditional procedures is given.
Tantalizing new physics from the cosmic purview

The emergence of a highly improbable coincidence in cosmological observations speaks of a remarkably simple cosmic expansion. Compelling evidence now suggests that the Universe’s gravitational hori...
Do the Fermi Gamma-Ray Burst Monitor and Swift Burst Alert Telescope see the Same Short Gamma-Ray Bursts?

Compact binary system mergers are expected to generate gravitational radiation detectable by ground-based interferometers. A subset of these, the merger of a neutron star with another neutron star or a black hole, are also the most popular model for the production of short gamma-ray bursts (GRBs). The Swift Burst Alert Telescope (BAT) and the Fermi Gamma-ray Burst Monitor (GBM) trigger on short GRBs (SGRBs) at rates that reflect their relative sky exposures, with the BAT detecting 10 per year compared to about 45 for GBM. We examine the SGRB populations detected by Swift BAT and Fermi GBM. We find that the Swift BAT triggers on weaker SGRBs than Fermi GBM, providing they occur close to the center of the BAT field of view, and that the Fermi GBM SGRB detection threshold remains flatter across its field of view. Overall, these effects combine to give the instruments the same average sensitivity, and account for the SGRBs that trigger one instrument but not the other. We do not find any evidence that the BAT and GBM are detecting significantly different populations of SGRBs. Both instruments can detect untriggered SGRBs using ground searches seeded with time and position. The detection of SGRBs below the on-board triggering sensitivities of Swift BAT and Fermi GBM increases the possibility of detecting and localizing the electromagnetic counterparts of gravitational wave (GW) events seen by the new generation of GW detectors.
Extended Quantum Conditional Entropy and Quantum Uncertainty Inequalities

Quantum states can be subjected to classical measurements, whose incompatibility, or uncertainty, can be quantified by a comparison of certain entropies. There is a long history of such entropy inequalities between position and momentum. Recently these inequalities have been generalized to the tensor product of several Hilbert spaces and we show here how their derivations can be shortened to a few lines and how they can be generalized. Our proofs utilize the technique of the original derivation of strong subadditivity of the von Neumann entropy.
Collisional Fragmentation Is Not a Barrier to Close-in Planet Formation

Collisional fragmentation is shown to not be a barrier to rocky planet formation at small distances from the host star. Simple analytic arguments demonstrate that rocky planet formation via collisions of homogeneous gravity-dominated bodies is possible down to distances of order the Roche radius ($r_\mathrm{Roche}$). Extensive N-body simulations with initial bodies ${\gtrsim}1700$ km that include plausible models for fragmentation and merging of gravity-dominated bodies confirm this conclusion and demonstrate that rocky planet formation is possible down to ${\sim}$1.1 $r_\mathrm{Roche}$. At smaller distances, tidal effects cause collisions to be too fragmenting to allow mass build-up to a final, dynamically stable planetary system. We argue that even differentiated bodies can accumulate to form planets at distances that are not much larger than $r_\mathrm{Roche}$.
Critical Phenomena in Plasma Membrane Organization and Function.

Lateral organization in the plane of the plasma membrane is an important driver of biological processes. The past dozen years have seen increasing experimental support for the notion that lipid org...
CoReNet: Coherent 3D Scene Reconstruction from a Single RGB Image

Advances in deep learning techniques have allowed recent work to reconstruct the shape of a single object given only one RBG image as input. Building on common encoder-decoder architectures for this task, we propose three extensions: (1) ray-traced skip connections that propagate local 2D information to the output 3D volume in a physically correct manner; (2) a hybrid 3D volume representation that enables building translation equivariant models, while at the same time encoding fine object details without an excessive memory footprint; (3) a reconstruction loss tailored to capture overall object geometry. Furthermore, we adapt our model to address the harder task of reconstructing multiple objects from a single image. We reconstruct all objects jointly in one pass, producing a coherent reconstruction, where all objects live in a single consistent 3D coordinate frame relative to the camera and they do not intersect in 3D space. We also handle occlusions and resolve them by hallucinating the missing object parts in the 3D volume. We validate the impact of our contributions experimentally both on synthetic data from ShapeNet as well as real images from Pix3D. Our method improves over the state-of-the-art single-object methods on both datasets. Finally, we evaluate performance quantitatively on multiple object reconstruction with synthetic scenes assembled from ShapeNet objects.
Clinical symptoms among ambulatory patients tested for SARS-CoV-2

We compared symptoms and characteristics of 4961 ambulatory patients with and without laboratory-confirmed severe acute respiratory syndrome coronavirus 2 infection. Findings indicate that clinical symptoms alone would be insufficient to distinguish between coronavirus disease 2019 and other respiratory infections (eg, influenza) and/or to evaluate the effects of preventive interventions (eg, vaccinations).
1H NMR Spectrum: A Team-Based Tabletop Game for Molecular Structure Elucidation

The 1H NMR Spectrum game, the first example of a team-based tabletop game focused on elucidating the structures of organic small molecules using 1H NMR spectra, was developed and deployed in a college-level organic chemistry lecture course and laboratory course. The tabletop game was designed as a collaborative and competitive group activity to encourage multiple rounds of play to help students reinforce their 1H NMR spectra interpretation skills. While playing in either team-based or free-for-all mode, students analyzed the provided chemical shifts, splitting patterns, integrations, and molecular formula within a designated time limit to correctly deduce the structure associated with the 1H NMR spectrum. After playing the game, students in a lecture course and a laboratory course self-reported that they felt more comfortable solving 1H NMR spectroscopy questions, found the game to be an appealing study aid, and were able to complete multiple rounds of play to strengthen their skills in interpreting 1H NMR spectra. The 1H NMR Spectrum tabletop game may serve as an engaging and competitive group learning tool to supplement teaching on 1H NMR spectroscopy.
Utilizing temporal measurements from UAVs to assess root lodging in maize and its impact on productivity

Abstract Both stalk and root lodging can cause significant yield losses in maize; however, maize plants are often able to recover from root lodging. There is potential among breeding programs for developing lines that are more tolerant and can more rapidly recover from root lodging. We assessed the incidence of root lodging utilizing end-of-season lodging scores collected among the Genomes 2 Fields (G2F) initiative trials and found a large yet variable incidence of lodging across states, years, and genotypes. Lodging in this dataset was scored manually at the end of the season, and little is known about the drivers of lodging and lodging recovery. We therefore developed an approach for utilizing temporal plant height measurements collected from unmanned aerial vehicles to capture in-season lodging and recovery in a yield trial consisting of 24 maize hybrids planted in replicate under two dates and three planting densities in St Paul, MN in the summers of 2018 and 2019. We found that growth rates during vegetative development as well as the developmental timing of plants when exposed to a storm are predictive of the amount of lodging maize plots will experience. We also found that utilizing temporal height measurements can help in not just estimating lodging and early vegetative growth rates, but that utilizing these estimates can also aid in assessing end of season yield.
Kernel Methods for Cooperative Multi-Agent Contextual Bandits.

Cooperative multi-agent decision making involves a group of agents cooperatively solving learning problems while communicating over a network with delays. In this paper, we consider the kernelised contextual bandit problem, where the reward obtained by an agent is an arbitrary linear function of the contexts' images in the related reproducing kernel Hilbert space (RKHS), and a group of agents must cooperate to collectively solve their unique decision problems. For this problem, we propose \textsc{Coop-KernelUCB}, an algorithm that provides near-optimal bounds on the per-agent regret, and is both computationally and communicatively efficient. For special cases of the cooperative problem, we also provide variants of \textsc{Coop-KernelUCB} that provides optimal per-agent regret. In addition, our algorithm generalizes several existing results in the multi-agent bandit setting. Finally, on a series of both synthetic and real-world multi-agent network benchmarks, we demonstrate that our algorithm significantly outperforms existing benchmarks.
Stability-Optimized High Order Methods and Stiffness Detection for Pathwise Stiff Stochastic Differential Equations

Stochastic differential equations (SDE) often exhibit large random transitions. This property, which we denote as pathwise stiffness, causes transient bursts of stiffness which limit the allowed step size for common fixed time step explicit and drift-implicit integrators. Here we present a HPC-driven method for deriving high strong order methods for stochastic differential equations. Utilizing GPU-accelerated global optimization, we numerically solve a constrained optimization problem which results stability-optimized adaptive methods of strong order 1.5 for SDEs. The resulting explicit methods are shown to exhibit substantially enlarged stability regions which allows for them to solve pathwise stiff biological models orders of magnitude more efficiently than previous methods like SRIW1 and Euler-Maruyama. These methods are benchmarked on a range of semi-stiff problems and demonstrate speedups between 6x previous adaptive algorithms while showing computationally infeasibility of fixed time step integrators on some of these test equations.