cssi/SciSciGPT-SciSciNet huggingface dataset:
Contact surgery and supporting open books

Let .M;/ be a contact 3‐manifold. We present two new algorithms, the first of which converts an open book .U;a/ supporting .M;/ with connected binding into a contact surgery diagram. The second turns a contact surgery diagram for.M;/ into a supporting open book decomposition. These constructions lead to a refinement of a result of Ding and Geiges [7], which states that every such .M;/ may be obtained by contact surgery from .S 3 ; std/, as well as bounds on the support norm and genus (Etnyre and Ozbagci [14]) of contact manifolds obtained by surgery in terms of classical link data. We then introduce Kirby moves called ribbon moves, which use mapping class relations to modify contact surgery diagrams. Any two surgery diagrams of the same contact 3‐manifold are related by a sequence of Legendrian isotopies and ribbon moves. As most of our results are computational in nature, a number of examples are analyzed. 57R17; 57M25
Structured Linearization of Discrete Mechanical Systems for Analysis and Optimal Control

Variational integrators are well-suited for simulation of mechanical systems because they preserve mechanical quantities about a system such as momentum, or its change if external forcing is involved, and holonomic constraints. While they are not energy-preserving they do exhibit long-time stable energy behavior. However, variational integrators often simulate mechanical system dynamics by solving an implicit difference equation at each time step, one that is moreover expressed purely in terms of configurations at different time steps. This paper formulates the first- and second-order linearizations of a variational integrator in a manner that is amenable to control analysis and synthesis, creating a bridge between existing analysis and optimal control tools for discrete dynamic systems and variational integrators for mechanical systems in generalized coordinates with forcing and holonomic constraints. The forced pendulum is used to illustrate the technique. A second example solves the discrete Linear Quadratic Regulator (LQR) problem to find a locally stabilizing controller for a 40 DOF system with six constraints.
A new concept for searching for time-reversal symmetry violation using Pa-229 ions trapped in optical crystals

Certain pear-shaped nuclei are expected to have enhanced sensitivity to time-reversal and parity-violating interactions originating within the nuclear medium. In particular, Protactinium-229 is thought to be about 100,000 times more sensitive than Mercury-199 which currently sets some of the most stringent limits for these types of interactions. Several challenges would first have to be addressed in order to take advantage of this discovery potential. First, there is not currently a significant source of Pa-229 (1.5 day half-life); however, there are plans to harvest Pa-229 at the Facility for Rare Isotope Beams at Michigan State University. Second, the spin-5/2 nucleus of Pa-229 limits its coherence time while also making it sensitive to systematic effects related to local electric field gradients. On the other hand, this also give Pa-229 an additional source of signal in the form of a magnetic quadrupole moment (MQM) which violates the same symmetries as an EDM but is not observable in spin-1/2 systems. Third, in order to compensate for the small atom numbers and short coherence times, the Pa-229 atoms would have to be probed with exceptionally large electric and magnetic fields that may be possible if Pa-229 ions are embedded inside an optical crystal. We will describe some aspects of this concept using the stable Praseodymium-141 isotope as a surrogate which has the same nuclear spin and similar atomic structure of Pa-229.
Color-flavor transformation for the special unitary group

Abstract We extend Zirnbauer's color-flavor transformation in the fermionic sector to the case of the special unitary group. The transformation allows a certain integral over SU( N c ) color matrices to be transformed into an integral over flavor matrices which parameterize the coset space U(2 N f )/U( N f )×U( N f ). Integrals of the type considered appear, for example, in the partition function of lattice gauge theory.
Juniper: An Open-Source Nonlinear Branch-and-Bound Solver in Julia

Nonconvex mixed-integer nonlinear programs (MINLPs) represent a challenging class of optimization problems that often arise in engineering and scientific applications. Because of nonconvexities, these programs are typically solved with global optimization algorithms, which have limited scalability. However, nonlinear branch-and-bound has recently been shown to be an effective heuristic for quickly finding high-quality solutions to large-scale nonconvex MINLPs, such as those arising in infrastructure network optimization. This work proposes Juniper, a Julia-based open-source solver for nonlinear branch-and-bound. Leveraging the high-level Julia programming language makes it easy to modify Juniper’s algorithm and explore extensions, such as branching heuristics, feasibility pumps, and parallelization. Detailed numerical experiments demonstrate that the initial release of Juniper is comparable with other nonlinear branch-and-bound solvers, such as Bonmin, Minotaur, and Knitro, illustrating that Juniper provides a strong foundation for further exploration in utilizing nonlinear branch-and-bound algorithms as heuristics for nonconvex MINLPs.
On the role of system size in Hall MHD magnetic reconnection

We study the effects of the Hall electric field on magnetic island coalescence in the large island limit and find evidence for both an elongated electron current sheet layer with a Sweet-Parker-like reconnection rate and a collapsed, Petschek-like electron sheet with a peak reconnection rate approaching the 0.1vAB0 Hall MHD rate. The state observed in our simulations appears to depend on the grid scale. Furthermore, even at the largest system sizes, we find that flux-pileup effects cause the islands to “bounce” despite the presence of a collapsed current sheet allowing fast instantaneous reconnection. The average reconnection rate in the large island limit is slow though the peak reconnection rate is fast.
Statistical Inference for the Population Landscape via Moment Adjusted Stochastic Gradients

Modern statistical inference tasks often require iterative optimization methods to compute the solution. Convergence analysis from an optimization viewpoint informs us only how well the solution is approximated numerically but overlooks the sampling nature of the data. In contrast, recognizing the randomness in the data, statisticians are keen to provide uncertainty quantification, or confidence, for the solution obtained by using iterative optimization methods. The paper makes progress along this direction by introducing moment‐adjusted stochastic gradient descent: a new stochastic optimization method for statistical inference. We establish non‐asymptotic theory that characterizes the statistical distribution for certain iterative methods with optimization guarantees. On the statistical front, the theory allows for model misspecification, with very mild conditions on the data. For optimization, the theory is flexible for both convex and non‐convex cases. Remarkably, the moment adjusting idea motivated from ‘error standardization’ in statistics achieves a similar effect to acceleration in first‐order optimization methods that are used to fit generalized linear models. We also demonstrate this acceleration effect in the non‐convex setting through numerical experiments.
HOMOTOPY RELATIONS FOR TOPOLOGICAL VOA

We consider a parameter-dependent version of the homotopy associative part of the Lian–Zuckerman homotopy algebra and provide an interpretation of the multilinear operations of this algebra in terms of integrals over certain polytopes. We explicitly prove the pentagon relation up to homotopy and propose a construction of the higher operations.
Planar relative Schottky sets and quasisymmetric maps

A relative Schottky set in a planar domain Ω is a subset of Ω obtained by removing from Ω open geometric discs whose closures are in Ω and are pairwise disjoint. In this paper we study quasisymmetric and related maps between relative Schottky sets of measure zero. We prove, in particular, that quasisymmetric maps between such sets in Jordan domains are conformal, locally bi-Lipschitz, and that their first derivatives are locally Lipschitz. We also provide a locally bi-Lipschitz uniformization result for relative Schottky sets in Jordan domains and establish rigidity with respect to local quasisymmetric maps for relative Schottky sets in the unit disc.
Entanglement and Fast Quantum Thermalization in Heavy Ion Collisions

Let A be subsystem of a larger system A ∪ B and ψ be a typical state from the subspace of the Hilbert space ℋAB satisfying an energy constraint. Then ρA(ψ) = TrB|ψ〉〈ψ| is nearly thermal. We discuss how this observation is related to fast thermalization of the central region ( ≈ A) in heavy ion collisions (HIC), where B represents other degrees of freedom (soft modes, hard jets, collinear particles) outside of A. Entanglement between the modes in A and B play a central role: the entanglement entropy SA increases rapidly in the collision. In gauge–gravity duality, SA is related to the area of extremal surfaces in the bulk, which can be studied using gravitational duals.
X-ray reflected spectra from accretion disk models. I. Constant density atmospheres

We present new models for illuminated accretion disks, their structure, and reprocessed emission. We consider the effects of incident X-rays on the surface of an accretion disk by simultaneously solving the equations of radiative transfer, energy balance, and ionization equilibrium over a large range of column densities. We assume plane-parallel geometry and azimuthal symmetry, such that each calculation corresponds to a ring at a given distance from the central object. Our models include recent and complete atomic data for K-shell processes of the iron and oxygen isonuclear sequences. We examine the effect on the spectrum of fluorescent Kα line emission and absorption in the emitted spectrum. We also explore the dependence of the spectrum on the strength of the incident X-rays and other input parameters, and discuss the importance of Comptonization on the emitted spectrum.
Higgs Physics and Supersymmetry

A brief overview of Higgs physics and of supersymmetry is given. The central theme of the overview is to explore the implications of the recent discovery of a Higgs-like particle regarding the prospects for the discovery of supersymmetry assuming that it is indeed the spin-0 CP even boson that enters in the spontaneous breaking of the electroweak symmetry. The high mass of the Higgs-like boson at ~125 GeV points to the weak scale of supersymmetry that enters in the loop correction to the Higgs boson mass, to be relatively high, i.e. in the TeV region. However, since more than one independent mass scales enter in softly broken supersymmetry, the allowed parameter space of supersymmetric models can allow a small Higgs mixing parameter μ and light gaugino masses consistent with a ~125 GeV Higgs boson mass. Additionally some light third generation sfermions, i.e. the stop and the stau are also permissible. Profile likelihood analysis of a class of SUGRA models indicates that mA>300 GeV which implies one is in the decoupling phase and the Higgs couplings are close to the standard model in this limit. Thus a sensitive measurement of the Higgs couplings with fermions and with the vector bosons is needed to detect beyond the standard model effects. Other topics discussed include dark matter, proton stability, and the Stueckelberg extended models as probes of new physics. A brief discussion of the way forward in the post Higgs discovery era is given.
Statistical analysis of the road network of India

In this paper we study the Indian highway network as a complex network where the junction points are considered as nodes, and the links are formed by an existing connection. We explore the topological properties and community structure of the network. We observe that the Indian highway network displays small-world properties and is assortative in nature. We also identify the most important road-junctions (or cities) in the highway network based on the betweenness centrality of the node. This could help in identifying the potential congestion points in the network. Our study is of practical importance and could provide a novel approach to reduce congestion and improve the performance of the highway network.
Polarized Synchrotron Emissivities and Absorptivities for Relativistic Thermal, Power-Law, and Kappa Distribution Functions

Synchrotron emission and absorption determine the observational appearance of many astronomical systems. In this paper, we describe a numerical scheme for calculating synchrotron emissivities and absorptivities in all four Stokes parameters for arbitrary gyrotropic electron distribution functions, building on earlier work by Leung, Gammie, and Noble. We use this technique to evaluate the emissivities and the absorptivities for a thermal (Maxwell-Juttner), isotropic powerlaw, and isotropic kappa distribution function. The latter contains a power-law tail at high particle energies that smoothly merges with a thermal core at low energies, as is characteristic of observed particle spectra in collisionless plasmas. We provide fitting formulae and error bounds on the fitting formulae for use in codes that solve the radiative transfer equation. The numerical method and the fitting formulae are implemented in a compact C library called symphony. We find that: the kappa distribution has a source function that is indistinguishable from a thermal spectrum at low frequencies and transitions to the characteristic
Dimension reduction for semidefinite programs via Jordan algebras

We propose a new method for simplifying semidefinite programs (SDP) inspired by symmetry reduction. Specifically, we show if an orthogonal projection map satisfies certain invariance conditions, restricting to its range yields an equivalent primal–dual pair over a lower-dimensional symmetric cone—namely, the cone-of-squares of a Jordan subalgebra of symmetric matrices. We present a simple algorithm for minimizing the rank of this projection and hence the dimension of this subalgebra. We also show that minimizing rank optimizes the direct-sum decomposition of the algebra into simple ideals, yielding an optimal “block-diagonalization” of the SDP. Finally, we give combinatorial versions of our algorithm that execute at reduced computational cost and illustrate effectiveness of an implementation on examples. Through the theory of Jordan algebras, the proposed method easily extends to linear and second-order-cone programming and, more generally, symmetric cone optimization.
CPIC: A Curvilinear Particle-in-Cell Code for Plasma–Material Interaction Studies

We describe a new electrostatic particle-in-cell (PIC) code in curvilinear geometry called curvilinear PIC (CPIC). The code models the microscopic (kinetic) evolution of a plasma with the PIC method, coupled with an adaptive computational grid that can conform to arbitrarily shaped domains. CPIC is particularly suited for multiscale problems associated with the interaction of complex objects with plasmas. A map is introduced between the physical space and the logical space, where the grid is uniform and Cartesian. In CPIC, most of the operations are performed in logical space. CPIC was designed following criteria of versatility, robustness, and performance. Its main features are the use of structured meshes, a scalable field solver based on the black box multigrid algorithm and a hybrid mover, where particles' position is in logical space while the velocity is in physical space. Test examples involving the interaction of a plasma with material boundaries are presented.
Real-time coherent diffraction inversion using deep generative networks

Phase retrieval, or the process of recovering phase information in reciprocal space to reconstruct images from measured intensity alone, is the underlying basis to a variety of imaging applications including coherent diffraction imaging (CDI). Typical phase retrieval algorithms are iterative in nature, and hence, are time-consuming and computationally expensive, making real-time imaging a challenge. Furthermore, iterative phase retrieval algorithms struggle to converge to the correct solution especially in the presence of strong phase structures. In this work, we demonstrate the training and testing of CDI NN, a pair of deep deconvolutional networks trained to predict structure and phase in real space of a 2D object from its corresponding far-field diffraction intensities alone. Once trained, CDI NN can invert a diffraction pattern to an image within a few milliseconds of compute time on a standard desktop machine, opening the door to real-time imaging.
Teaching and understanding of quantum interpretations in modern physics courses

Just as expert physicists vary in their personal stances on interpretation in quantum mechanics, instructors vary on whether and how to teach interpretations of quantum phenomena in introductory modern physics courses. In this paper, we document variations in instructional approaches with respect to interpretation in two similar modern physics courses recently taught at the University of Colorado, and examine associated impacts on student perspectives regarding quantum physics. We find students are more likely to prefer realist interpretations of quantum-mechanical systems when instructors are less explicit in addressing student ontologies. We also observe contextual variations in student beliefs about quantum systems, indicating that instructors who choose to address questions of ontology in quantum mechanics should do so explicitly across a range of topics.
Field dependent specific-heat of rare earth manganites

Abstract The low-temperature specific heat C(H) of several rare-earth manganites (La0.7Sr0.3MnO3, Nd0.5Sr0.5MnO3, Pr0.5Sr0.5MnO3, La0.67Ca0.33MnO3, La0.5Ca0.5MnO3, La0.45Ca0.55MnO3 and La0.33Ca0.67MnO3) was measured as a function of magnetic field. We observed behavior consistent with thermodynamic expectations, i.e., C(H) decreases with field for ferromagnetic metallic compounds by an amount which is in quantitative agreement with spin-wave theory. We also find that C(H) increases with field in most compounds with a charge-ordered antiferromagnetic ground state. In compounds which show evidence of a coexistence of ferromagnetic metallic and antiferromagnetic charge-ordered states, C(H) displays some unusual non-equilibrium effects presumably associated with the phase-separation of the two states. We also observe a large anomalous low-temperature specific heat at the doping-induced metal–insulator transition (at x=0.50) in La1−xCaxMnO3.
Fluorescence correlation spectroscopy and nonlinear stochastic reaction-diffusion

The currently existing theory of fluorescence correlation spectroscopy (FCS) is based on the linear fluctuation theory originally developed by Einstein, Onsager, Lax, and others as a phenomenological approach to equilibrium fluctuations in bulk solutions. For mesoscopic reaction-diffusion systems with nonlinear chemical reactions among a small number of molecules, a situation often encountered in single-cell biochemistry, it is expected that FCS time correlation functions of a reaction-diffusion system can deviate from the classic results of Elson and Magde [ Biopolymers 1974, 13, 1 - 27]. We first discuss this nonlinear effect for reaction systems without diffusion. For nonlinear stochastic reaction-diffusion systems, there are no closed solutions; therefore, stochastic Monte Carlo simulations are carried out. We show that the deviation is small for a simple bimolecular reaction; the most significant deviations occur when the number of molecules is small and of the same order. Our results show that current linear FCS theory could be adequate for measurements on biological systems that contain many other sources of uncertainties. At the same time, it provides a framework for future measurements of nonlinear, fluctuating chemical reactions with high-precision FCS. Extending Delbruck-Gillespie's theory for stochastic nonlinear reactions with rapid stirring to reaction-diffusion systems provides a mesoscopic model for chemical and biochemical reactions at nanometric and mesoscopic levels, such as a single biological cell.
Quantum supergroups VI: roots of 1

A quantum covering group is an algebra with parameters q and $$\pi $$ subject to $$\pi ^2=1$$, and it admits an integral form; it specializes to the usual quantum group at $$\pi =1$$ and to a quantum supergroup of anisotropic type at $$\pi =-1$$. In this paper we establish the Frobenius–Lusztig homomorphism and Lusztig–Steinberg tensor product theorem in the setting of quantum covering groups at roots of 1. The specialization of these constructions at $$\pi =1$$ recovers Lusztig’s constructions for quantum groups at roots of 1.
Asymptotic Gluing of Asymptotically Hyperbolic Solutions to the Einstein Constraint Equations

We show that asymptotically hyperbolic solutions of the Einstein constraint equations with constant mean curvature can be glued in such a way that their asymptotic regions are connected.
Polaron transport of amorphous semiconductors with embedded crystallites

Near-room-temperature (narrow-band) polaron transport of an amorphous semiconductor with embedded annealing-induced semiconducting crystallites is treated within an effective-medium approach. Carri...
Dependence of X-Ray Burst Models on Nuclear Masses

X-ray burst model predictions of light curves and final composition of the nuclear ashes are affected by uncertain nuclear masses. However, not all of these masses are determined experimentally with sufficient accuracy. Here we identify remaining nuclear mass uncertainties in X-ray burst models using a one zone model that takes into account the changes in temperature and density evolution caused by changes in the nuclear physics. Two types of bursts are investigated - a typical mixed H/He burst with a limited rp-process and an extreme mixed H/He burst with an extended rp-process. When allowing for a 3$\sigma$ variation only three remaining nuclear mass uncertainties affect the light curve predictions of a typical H/He burst ($^{27}$P, $^{61}$Ga, and $^{65}$As), and only three additional masses affect the composition strongly ($^{80}$Zr, $^{81}$Zr, and $^{82}$Nb). A larger number of mass uncertainties remains to be addressed for the extreme H/He burst with the most important being $^{58}$Zn, $^{61}$Ga, $^{62}$Ge, $^{65}$As, $^{66}$Se, $^{78}$Y, $^{79}$Y, $^{79}$Zr, $^{80}$Zr, $^{81}$Zr, $^{82}$Zr, $^{82}$Nb, $^{83}$Nb, $^{86}$Tc, $^{91}$Rh, $^{95}$Ag, $^{98}$Cd, $^{99}$In, $^{100}$In, and $^{101}$In. The smallest mass uncertainty that still impacts composition significantly when varied by 3$\sigma$ is $^{85}$Mo with 16 keV uncertainty. For one of the identified masses, $^{27}$P, we use the isobaric mass multiplet equation (IMME) to improve the mass uncertainty, obtaining an atomic mass excess of -716(7) keV. The results provide a roadmap for future experiments at advanced rare isotope beam facilities, where all the identified nuclides are expected to be within reach for precision mass measurements.
A No-Boundary Method for Numerical Relativity

We propose a method for numerical relativity in which the spatial grid is finite and no outer boundary condition is needed. As a "proof of concept" we implement this method for the case of a self-gravitating, spherically symmetric scalar field.
MAKO: a pathfinder instrument for on-sky demonstration of low-cost 350 micron imaging arrays

Submillimeter cameras now have up to 10^4 pixels (SCUBA 2). The proposed CCAT 25-meter submillimeter telescope will feature a 1 degree field-of-view. Populating the focal plane at 350 microns would require more than 10^6 photon-noise limited pixels. To ultimately achieve this scaling, simple detectors and high-density multiplexing are essential. We are addressing this long-term challenge through the development of frequency-multiplexed superconducting microresonator detector arrays. These arrays use lumped-element, direct-absorption resonators patterned from titanium nitride films. We will discuss our progress toward constructing a scalable 350 micron pathfinder instrument focusing on fabrication simplicity, multiplexing density, and ultimately a low per-pixel cost.
A few points on point-to-point correlation functions

Abstract The short-time regime of QCD two-point correlation functions is examined through a QCD-Sum-Rule-inspired continuum model. QCD Sum Rule techniques are tested and alternate nucleon interpolating fields are discussed. The techniques presented here may be of practical use in determining heavy-light meson decay constants.
Cluster Algebras and Triangulated Surfaces Part II: Lambda Lengths

For any cluster algebra whose underlying combinatorial data can be encoded by a bordered surface with marked points, we construct a geometric realization in terms of suitable decorated Teichmueller space of the surface. On the geometric side, this requires opening the surface at each interior marked point into an additional geodesic boundary component. On the algebraic side, it relies on the notion of a non-normalized cluster algebra and the machinery of tropical lambda lengths. Our model allows for an arbitrary choice of coefficients which translates into a choice of a family of integral laminations on the surface. It provides an intrinsic interpretation of cluster variables as renormalized lambda lengths of arcs on the surface. Exchange relations are written in terms of the shear coordinates of the laminations, and are interpreted as generalized Ptolemy relations for lambda lengths. This approach gives alternative proofs for the main structural results from our previous paper, removing unnecessary assumptions on the surface.
Rapid Evolution of the Gaseous Exoplanetary Debris Around the White Dwarf Star HE 1349--2305

Observations of heavy metal pollution in white dwarf stars indicate that metal-rich planetesimals are frequently scattered into star-grazing orbits, tidally disrupted, and accreted onto the white dwarf surface, offering direct insight into the dynamical evolution of post-main-sequence exoplanetary systems. Emission lines from the gaseous debris in the accretion disks of some of these systems show variations on timescales of decades, and have been interpreted as the general relativistic precession of recently formed, elliptical disk. Here we present a comprehensive spectroscopic monitoring campaign of the calcium infrared triplet emission in one system, HE 1349--2305, which shows morphological emission profile variations suggestive of a precessing, asymmetric intensity pattern. The emission profiles are shown to vary on a timescale of one to two years, which is an order of magnitude shorter than what has been observed in other similar systems. We demonstrate that this timescale is likely incompatible with general relativistic precession, and consider alternative explanations for the rapid evolution including the propagation of density waves within the gaseous debris. We conclude with recommendations for follow-up observations, and discuss how the rapid evolution of the gaseous debris in HE 1349--2305 could be leveraged to test theories of exoplanetary debris disk evolution around white dwarf stars.
The performance of phaseless auxiliary-field quantum Monte Carlo on the ground state electronic energy of benzene.

The ground state electronic energy of benzene is the focus of a recent blind test by Eriksen and co-workers [arXiv:2008.02678]. In this note, we report the phaseless auxiliary-field quantum Monte Carlo (ph-AFQMC) results on the identical problem. We examine trial wavefunctions of the spin-restricted Hartree-Fock (RHF), and complete active space self-consistent field (CASSCF) with an active space of 6-electron and 6-orbital (i.e., CAS(6,6)) form for the cc-pVDZ basis set. ph-AFQMC+RHF deviates from the value where many methods agreed on (i.e., -863 m$E_h$) by -3.1(3) m$E_h$ whereas ph-AFQMC+CAS(6,6) deviates from the same value by -1.3(4) m$E_h$. In addition to this, we report the frozen core correlation energy of ph-AFQMC+RHF in the cc-pVTZ and cc-pVQZ basis sets as well as their complete basis set limit. Our findings highlight the accuracy, flexibility, and scalability of ph-AFQMC with simple trial wavefunctions.
The Weak Mixing Angle From TeV Scale Quark-Lepton Unification

Unified theories based on an extended left-right symmetric group, SU(4) × SU(2)4, are constructed in five dimensions. The compactification scale is assumed to be only a loop factor above the weak scale, so that the weak mixing angle is predicted to be close to its tree level value of 0.239. Boundary conditions in the 5th dimension break SU(4)→SU(3) × U(1)B−L, removing powerful constraints from KL→μe while allowing a reliable calculation of the leading logarithm corrections to sin 2θ. The compactification scale is expected in the 1 - 5 TeV region, depending on how SU(2)4 is broken. Two illustrative models are presented, and the experimental signal of the Z' gauge boson is discussed.
The Integration of Angular Velocity

A common problem in physics and engineering is determination of the orientation of an object given its angular velocity. When the direction of the angular velocity changes in time, this is a nontrivial problem involving coupled differential equations. Several possible approaches are examined, along with various improvements over previous efforts. These are then evaluated numerically by comparison to a complicated but analytically known rotation that is motivated by the important astrophysical problem of precessing black-hole binaries. It is shown that a straightforward solution directly using quaternions is most efficient and accurate, and that the norm of the quaternion is irrelevant. Integration of the generator of the rotation can also be made roughly as efficient as integration of the rotation. Both methods will typically be twice as efficient as naive vector- or matrix-based methods. Implementation by means of standard general-purpose numerical integrators is stable and efficient, so that such problems can be readily solved as part of a larger system of differential equations. Possible generalization to integration in other Lie groups is also discussed.
Electromigration-driven Evolution of the Surface Morphology and Composition for a Bi-Component Solid Film

A two PDEs-based model is developed for studies of a morphological and compositional evolution of a thermodynamically stable alloy surface in a strong electric field, assuming different and anisotropic diffusional mobilities of the two atomic components. The linear stability analysis of a planar surface and the computations of morphology coarsening are performed. It is shown that the conditions for instability and the characteristic wavelength and growth rate differ from their counterparts in a single-component film. Computational parametric analyses reveal the sensitivity of the scaling exponents to the electric field strength and to the magnitude of the anisotropies difference.
HADRON CORRELATION IN JETS

We review some recent experimental and theoretical work on the correlation among hadrons produced at intermediate pT at RHIC. The topics include: forward and backward asymmetry with and without trigger at mid-rapidity, associated-particle distribution on the near side, the Ω puzzle and its solution, associated particles on the away side, and two-jet recombination at LHC.
FIRST Principles to Design for Online, Synchronous High School CS Teacher Training and Curriculum Co-Design

The Covid-19 pandemic has offered new challenges and opportunities for teaching and research. It has forced constraints on in-person gathering of researchers, teachers, and students, and conversely, has also opened doors to creative instructional design. This paper describes a novel approach to designing an online, synchronous teacher professional development (PD) and curriculum co-design experience. It shares our work in bringing together high school teachers and researchers in four US states. The teachers participated in a 3-week summer PD on ideas of Distributed Computing and how to teach this advanced topic to high school students using NetsBlox, an extension of the Snap! block-based programming environment. The goal of the PD was to prepare teachers to engage in collaborative co-design of a 9-week curricular module for use in classrooms and schools. Between their own training and the co-design process, teachers co-taught a group of high school students enrolled in a remote summer internship at a university in North Carolina to pilot the learned units and leverage ideas from their teaching experience for subsequent curricular co-design. Formative and summative feedback from teachers suggest that this PD model was successful in meeting desired outcomes. Our generalizable FIRST principles—Flexibility, Innovativeness, Responsiveness (and Respect), Supports, and Teamwork (collaboration)—that helped make this unique PD successful, can help guide future CS teacher PD designs.
Boosting Weakly Supervised Object Detection with Progressive Knowledge Transfer

In this paper, we propose an effective knowledge transfer framework to boost the weakly supervised object detection accuracy with the help of an external fully-annotated source dataset, whose categories may not overlap with the target domain. This setting is of great practical value due to the existence of many off-the-shelf detection datasets. To more effectively utilize the source dataset, we propose to iteratively transfer the knowledge from the source domain by a one-class universal detector and learn the target-domain detector. The box-level pseudo ground truths mined by the target-domain detector in each iteration effectively improve the one-class universal detector. Therefore, the knowledge in the source dataset is more thoroughly exploited and leveraged. Extensive experiments are conducted with Pascal VOC 2007 as the target weakly-annotated dataset and COCO/ImageNet as the source fully-annotated dataset. With the proposed solution, we achieved an mAP of \(59.7\%\) detection performance on the VOC test set and an mAP of \(60.2\%\) after retraining a fully supervised Faster RCNN with the mined pseudo ground truths. This is significantly better than any previously known results in related literature and sets a new state-of-the-art of weakly supervised object detection under the knowledge transfer setting. Code: https://github.com/mikuhatsune/wsod_transfer.
Aging and the encoding of changes in events: The role of neural activity pattern reinstatement

When encountering unexpected event changes, memories of relevant past experiences must be updated to form new representations. Current models of memory updating propose that people must first generate memory-based predictions to detect and register that features of the environment have changed, then encode the new event features and integrate them with relevant memories of past experiences to form configural memory representations. Each of these steps may be impaired in older adults. Using functional MRI, we investigated these mechanisms in healthy young and older adults. In the scanner, participants first watched a movie depicting everyday activities in a day of an actor's life. They next watched a second nearly identical movie in which some scenes ended differently. Crucially, before watching the last part of each activity, the second movie stopped, and participants were asked to mentally replay how the activity previously ended. Three days later, participants were asked to recall the activities. Neural activity pattern reinstatement in medial temporal lobe (MTL) during the replay phase of the second movie was associated with detecting changes and with better memory for the original activity features. Reinstatements in posterior medial cortex (PMC) additionally predicted better memory for changed features. Compared to young adults, older adults showed a reduced ability to detect and remember changes and weaker associations between reinstatement and memory performance. These findings suggest that PMC and MTL contribute to change processing by reinstating previous event features, and that older adults are less able to use reinstatement to update memory for changed features.
Neural sensitivity to natural image statistics changes during middle childhood.

Natural images have properties that adults' behavioral and neural responses are sensitive to, but the development of this sensitivity is not clear. Behaviorally, children acquire adult-like sensitivity to natural image statistics during middle childhood (Ellemberg et al., 2012), but infants exhibit sensitivity to deviations of natural image structure (Balas & Woods, 2014). We used event-related potentials (ERPs) to examine sensitivity to natural image statistics during childhood at distinct processing stages (the P1 and N1 components). We presented children (5-10 years old) and adults with natural images varying in positive/negative contrast, and natural/synthetic texture appearance to compare electrophysiological responses to images that did or did not violate natural statistics. We hypothesized that children would acquire sensitivity to these deviations late in middle childhood. Instead, we observed significant responses to unnatural contrast and texture statistics at the N1 in all age groups. At the P1, however, only young children exhibited sensitivity to contrast polarity. The latter effect suggests greater sensitivity earlier in development to some violations of natural image statistics. We discuss these results in terms of changing patterns of invariant texture processing during middle childhood and ongoing refinement of the representations supporting natural image perception.
Financial Fragility during the COVID-19 Pandemic

Early in the COVID-19 pandemic, much of the US economy was closed to limit the virus’ spread, and several emergency interventions were implemented. Our analysis of older (45-75) respondents fielded in April-May of 2020 indicates that about one in five respondents was financially fragile and would have difficulty facing a mid-size emergency expense. Some subgroups were at particular risk of facing financial difficulties, especially younger respondents, those with larger families, Hispanics, and the low income. Moreover, the more financially literate were better able to handle such shocks, indicating that knowledge can provide some additional protection during a pandemic.
Review of orbital fractures in an urban level I trauma center

Purpose Orbital fractures are not uncommonly encountered in a level I trauma center. The incidence of adult orbital fractures in the United States is 10% to 25% among all facial fracture cases. Craniomaxillofacial trauma is typically managed by 3 different surgical specialties (Oral & Maxillofacial Surgery [OMFS], Otolaryngology [ENT], and Plastic & Reconstruction Surgery [PRS]). The purpose of our study was to understand the patterns and mechanisms of injury associated with orbital fractures and to develop standardized treatment protocols across all surgical specialties. Methods This was a retrospective chart review of patients who sustained orbital fractures that were surgically repaired at the Emory University Grady Memorial Hospital (GMH) between January 2012 and December 2016. The study inclusion criteria were (1) diagnosis of an orbital floor fracture, (2) age 18 years and greater, (3) treatment provided at the GMH by the craniomaxillofacial trauma team. Exclusion criteria were patient age less than 18 years and absence of surgical intervention. The predictor variables were (1) demographic characteristics, (2) injury detail, (3) involvement of other facial fractures, and (4) treatment variables. Patients were deidentified before data analysis. Statistical analysis was performed with χ2, Mann-Whitney U, and Kruskal-Wallis tests. Analyses were performed with the SPSS software (SPSS Inc., Chicago, IL), and P value of Results The initial chart review yielded 689 patients. Of these, 173 patients had been diagnosed with orbital fractures and met the inclusion criteria. The average patient age was 41.6 years, and most were males, with a male-to-female ratio of 3.3:1. Most fractures were caused by assault (39.3%), and 22.5% of the cases were bilateral. The left orbit was fractured more often than the right (40.5%). The orbital floor was the most common anatomic location (97.1%), and the maxilla was the most commonly involved bone (65.3%). The average time from consultation to surgical intervention was 8.7 ± 14.6 days, and the average time from surgical intervention to discharge was 5.1 ± 9.0 days. The transconjunctival incision was the most commonly used incision (63%), and the nonresorbable implant was the most commonly used implant (92.7%). Finally, the length of stay for simple orbital fractures was less than that for complex orbital fractures, with 1.5 days and 5.9 days, respectively. Conclusions Among the 3 major specialties (OMFS, PRS, ENT), there is no consensus with regard to the management of orbital fractures. Understanding the patterns and mechanisms of injury associated with orbital fractures can assist in developing standardized treatment protocols across all surgical specialties. This would ultimately allow for the uniformly high quality of surgical care for patients with maxillofacial fractures.
Mixed volume of small reaction networks

An important invariant of a chemical reaction network is its maximum number of positive steady states. This number, however, is in general difficult to compute. Nonetheless, there is an upper bound on this number — namely, a network’s mixed volume — that is easy to compute. Moreover, recent work has shown that, for certain biological signaling networks, the mixed volume does not greatly exceed the maximum number of positive steady states. Continuing this line of research, we further investigate this overcount and also compute the mixed volumes of small networks, those with only a few species or reactions.
Resilient State Estimation in Presence of Severe Coordinated Cyber-Attacks on Large-Scale Power Systems

Providing situational awareness in light of severe coordinated cyber-attacks on power grids, where many measurements may be untrusted, is necessary for reliable monitoring and resilient operation of the grid. In this scenario, the set of good measurements is by itself insufficient for state estimation due to loss of observability. In this paper, we present a resilient state estimation algorithm, based on output clustering. By augmenting the measurement set by respective cluster variables, the system observability is regained, and a reliable state estimate can be computed. We show the numerical performance of our proposed algorithm and its ability to successfully replace corrupted measurements using cluster variables through an example on the IEEE 24-bus power system.
Bipartite Causal Inference with Interference.

Statistical methods to evaluate the effectiveness of interventions are increasingly challenged by the inherent interconnectedness of units. Specifically, a recent flurry of methods research has addressed the problem of interference between observations, which arises when one observational unit’s outcome depends not only on its treatment but also the treatment assigned to other units. We introduce the setting of bipartite causal inference with interference, which arises when (1) treatments are defined on observational units that are distinct from those at which outcomes are measured and (2) there is interference between units in the sense that outcomes for some units depend on the treatments assigned to many other units. The focus of this work is to formulate definitions and several possible causal estimands for this setting, highlighting similarities and differences with more commonly considered settings of causal inference with interference. Toward an empirical illustration, an inverse probability of treatment weighted estimator is adapted from existing literature to estimate a subset of simplified, but interesting, estimands. The estimators are deployed to evaluate how interventions to reduce air pollution from 473 power plants in the U.S. causally affect cardiovascular hospitalization among Medicare beneficiaries residing at 18,807 zip code locations.
Air pollution and breast cancer risk in the Black Women's Health Study.

Abstract Background Air pollution contains numerous carcinogens and endocrine disruptors which may be relevant for breast cancer. Previous research has predominantly been conducted in White women; however, Black women may have higher air pollution exposure due to geographic and residential factors. Objective We evaluated the association between air pollution and breast cancer risk in a large prospective population of Black women. Methods We estimated annual average ambient levels of particulate matter Results With follow-up through 2015 (mean = 18.3 years), 2146 incident cases of breast cancer were confirmed. Higher exposure to NO2 or O3 was not associated with a higher risk of breast cancer. For PM2.5, although we observed no association overall, there was evidence of modification by geographic region for both ER- (p for heterogeneity = 0.01) and premenopausal breast cancer (p for heterogeneity = 0.01). Among women living in the Midwest, an IQR increase in PM2.5 (2.87 μg/m3), was associated with a higher risk of ER- (HR = 1.53, 95% CI: 1.07–2.19) and premenopausal breast cancer (HR = 1.32, 95% CI: 1.03–1.71). In contrast, among women living in the South, PM2.5 was inversely associated with both ER- (HR = 0.74, 95% CI: 0.56–0.97) and premenopausal breast cancer risk (HR = 0.75, 95% CI: 0.62–0.91). Discussion Overall, we observed no association between air pollution and increased breast cancer risk among Black women, except perhaps among women living in the Midwestern US.
Mistargeting of secretory cargo in retromer-deficient cells.

Intracellular trafficking is a basic and essential cellular function required for delivery of proteins to the appropriate subcellular destination; this process is especially demanding in professional secretory cells, which synthesize and secrete massive quantities of cargo proteins via regulated exocytosis. The Drosophila larval salivary glands are professional secretory cells that synthesize and secrete mucin proteins at the onset of metamorphosis. Using the larval salivary glands as a model system, we have identified a role for the highly conserved retromer complex in trafficking of secretory granule membrane proteins. We demonstrate that retromer-dependent trafficking via endosomal tubules is induced at the onset of secretory granule biogenesis, and that recycling via endosomal tubules is required for delivery of essential secretory granule membrane proteins to nascent granules. Without retromer function, nascent granules do not contain the proper membrane proteins; as a result, cargo from these defective granules is mistargeted to Rab7-positive endosomes, where it progressively accumulates to generate dramatically enlarged endosomes. Retromer complex dysfunction is strongly associated with neurodegenerative diseases, including Alzheimer9s disease, characterized by accumulation of amyloid β (Aβ). We show that ectopically expressed amyloid precursor protein (APP) undergoes regulated exocytosis in salivary glands and accumulates within enlarged endosomes in retromer-deficient cells. These results highlight recycling of secretory granule membrane proteins as a critical step during secretory granule maturation and provide new insights into our understanding of retromer complex function in secretory cells. These findings also suggest that missorting of secretory cargo, including APP, may contribute to the progressive nature of neurodegenerative disease.