cssi/SciSciGPT-SciSciNet huggingface dataset:
CORE GAS SLOSHING IN ABELL 1644

We present an analysis of a 72 ks Chandra observation of the double cluster Abell 1644 (z = 0.047). The X-ray temperatures indicate that the masses are M 500 = (2.6 ± 0.4) × 1014 h –1 M ☉ for the northern sub-cluster and M 500 = (3.1 ± 0.4) × 1014 h –1 M ☉ for the southern, main cluster. We identify a sharp edge in the radial X-ray surface brightness of the main cluster, which we find to be a cold front, with a jump in temperature of a factor of ~3. This edge possesses a spiral morphology characteristic of core gas sloshing around the cluster potential minimum. We present observational evidence, supported by hydrodynamic simulations, that the northern sub-cluster is the object that initiated the core gas sloshing in the main cluster at least 700 Myr ago. We discuss reheating of the main cluster's core gas via two mechanisms brought about by the sloshing gas: first, the release of gravitational potential energy gained by the core's displacement from the potential minimum, and second, a dredging inward of the outer, higher entropy cluster gas along finger-shaped streams. We find that the available gravitational potential energy is small compared to the energy released by the cooling gas in the core.
Flow of a viscous nematic fluid around a sphere

We analyse the creeping flow generated by a spherical particle moving through a viscous fluid with nematic directional order, in which momentum diffusivity is anisotropic and which opposes resistance to bending. Specifically, we provide closed-form analytical expressions for the response function, i.e. the equivalent to Stokes’s drag formula for nematic fluids. Particular attention is given to the rotationally pseudo-isotropic condition defined by zero resistance to bending, and to the strain pseudo-isotropic condition defined by isotropic momentum diffusivity. We find the former to be consistent with the rheology of biopolymer networks and the latter to be closer to the rheology of nematic liquid crystals. These ‘pure’ anisotropic conditions are used to benchmark existing particle tracking microrheology methods that provide effective directional viscosities by applying Stokes’s drag law separately in different directions. We find that the effective viscosity approach is phenomenologically justified in rotationally isotropic fluids, although it leads to significant errors in the estimated viscosity coefficients. On the other hand, the mere concept of directional effective viscosities is found to be misleading in fluids that oppose an appreciable resistance to bending. Finally, we observe that anisotropic momentum diffusivity leads to asymmetric streamline patterns displaying enhanced (reduced) streamline deflection in the directions of lower (higher) diffusivity. The bending resistance of the fluid is found to modulate the asymmetry of streamline deflection. In some cases, the combined effects of both anisotropy mechanisms leads to streamline patterns that converge towards the sphere.
Alignment of vorticity and rods with Lagrangian fluid stretching in turbulence

Stretching in continuum mechanics is naturally described using the Cauchy–Green strain tensors. These tensors quantify the Lagrangian stretching experienced by a material element, and provide a powerful way to study processes in turbulent fluid flows that involve stretching such as vortex stretching and alignment of anisotropic particles. Analysing data from a simulation of isotropic turbulence, we observe preferential alignment between rods and vorticity. We show that this alignment arises because both of these quantities independently tend to align with the strongest Lagrangian stretching direction, as defined by the maximum eigenvector of the left Cauchy–Green strain tensor. In particular, rods approach almost perfect alignment with the strongest stretching direction. The alignment of vorticity with stretching is weaker, but still much stronger than previously observed alignment of vorticity with the eigenvectors of the Eulerian strain rate tensor. The alignment of strong vorticity is almost the same as that of rods that have experienced the same stretching.
Some New Results on Sample Path Optimality in Ergodic Control of Diffusions

We present some new results on sample path optimality for the ergodic control problem of a class of nondegenerate diffusions controlled through the drift. The hypothesis most often used in the literature to ensure the existence of an almost sure sample path optimal stationary Markov control requires finite second moments of the first hitting times $\tau$ of bounded domains over all admissible controls. We show that this can be considerably weakened: ${\mathbb {E}}[\tau ^2]$ may be replaced with ${\mathbb {E}}[\tau \ln ^+(\tau)]$ , thus reducing the required rate of convergence of averages from polynomial to logarithmic. A Foster–Lyapunov condition that guarantees this is also exhibited. Moreover, we study a large class of models that are neither uniformly stable nor have a near-monotone running cost, and we exhibit sufficient conditions for the existence of a sample path optimal stationary Markov control.
Dynamical systems study in single-phase multiferroic materials

Electric-field–induced magnetization switching in single phase multiferroic materials is intriguing for both fundamental studies and potential technological applications. Here we develop a framework to study the switching dynamics of coupled polarization and magnetization in such multiferroic materials. With the coupling term between the polarization and magnetization as an invariant dictated by the Dzyaloshinsky-Moriya vector, the dynamical systems study reveals switching failures and oscillatory mode of magnetization if the polarization and magnetization relax slowly during switching.
Bound Outflows, Unbound Ejecta, and the Shaping of Bipolar Remnants during Stellar Coalescence

Recent observations have revealed that the remnants of stellar-coalescence transients are bipolar. This raises the questions of how these bipolar morphologies arise and what they teach us about the mechanisms of mass ejection during stellar mergers and common-envelope phases. In this paper, we analyze hydrodynamic simulations of the lead-in to binary coalescence, a phase of unstable Roche lobe overflow that takes the binary from the Roche limit separation to the engulfment of the more compact accretor within the envelope of the extended donor. As mass transfer runs away at increasing rates, gas trails away from the binary. Contrary to previous expectations, early mass loss from the system remains bound to the binary and forms a circumbinary torus. Later ejecta, generated as the accretor grazes the surface of the donor, have very different morphologies and are unbound. These two components of mass loss from the binary interact as later, higher-velocity ejecta collide with the circumbinary torus formed by earlier mass loss. Unbound ejecta are redirected toward the poles, and escaping material creates a bipolar outflow. Our findings show that the transition from bound to unbound ejecta from coalescing binaries can explain the bipolar nature of their remnants, with implications for our understanding of the origin of bipolar remnants of stellar-coalescence transients and, perhaps, some preplanetary nebulae.
Second Minimal Orbits, Sharkovski Ordering and Universality in Chaos

This paper introduces the notion of second minimal n-periodic orbits of continuous maps on the interval according to whether n is a successor of the minimal period of the map in the Sharkovski ordering. We pursue the classification of second minimal 7-orbits in terms of cyclic permutations and digraphs. It is proven that there are nine types of second minimal 7-orbits with accuracy up to inverses. The result is applied to the problem of the distribution of periodic windows within the chaotic regime of the bifurcation diagram of the one-parameter family of unimodal maps. It is revealed that by fixing the maximum number of appearances of periodic windows, there is a universal pattern of distribution. In particular, the first appearance of all the orbits is always a minimal orbit, while the second appearance is a second minimal orbit. It is observed that the second appearance of the 7-orbit is a second minimal 7-orbit with a Type 1 digraph. The reason for the relevance of the Type 1 second minimal orbit is the fact that the topological structure of the unimodal map with a single maximum, is equivalent to the structure of the Type 1 piecewise monotonic endomorphism associated with the second minimal 7-orbit. Yet another important report of this paper is the revelation of universal pattern dynamics with respect to an increased number of appearances.
Atomic and Molecular Phases of the Interstellar Medium

This review covers four current questions in the behavior of the atomic and molecular interstellar medium. These include whether the atomic gas originates primarily in cold streams or hot flows onto galaxies; what the filling factor of cold gas actually is in galactic regions observationally determined to be completely molecular; whether molecular hydrogen determines or merely traces star formation; and whether gravity or turbulence drives the dynamical motions observed in interstellar clouds, with implications on their star formation properties.
TESS: A RELATIVISTIC HYDRODYNAMICS CODE ON A MOVING VORONOI MESH

We have generalized a method for the numerical solution of hyperbolic systems of equations using a dynamic Voronoi tessellation of the computational domain. The Voronoi tessellation is used to generate moving computational meshes for the solution of multidimensional systems of conservation laws in finite-volume form. The mesh-generating points are free to move with arbitrary velocity, with the choice of zero velocity resulting in an Eulerian formulation. Moving the points at the local fluid velocity makes the formulation effectively Lagrangian. We have written the TESS code to solve the equations of compressible hydrodynamics and magnetohydrodynamics for both relativistic and non-relativistic fluids on a dynamic Voronoi mesh. When run in Lagrangian mode, TESS is significantly less diffusive than fixed mesh codes and thus preserves contact discontinuities to high precision while also accurately capturing strong shock waves. TESS is written for Cartesian, spherical, and cylindrical coordinates and is modular so that auxiliary physics solvers are readily integrated into the TESS framework and so that this can be readily adapted to solve general systems of equations. We present results from a series of test problems to demonstrate the performance of TESS and to highlight some of the advantages of the dynamic tessellation method for solving challenging problems in astrophysical fluid dynamics.
Congenial algebras: Extensions and examples

We study the congeniality property of algebras, as defined by Bao, He, and Zhang, to establish a version of Auslander’s theorem for various families of filtered algebras. It is shown that the prope...
Symmetric fracton matter: Twisted and enriched

Abstract In this paper, we explore the interplay between symmetry and fracton order, motivated by the analogous close relationship for topologically ordered systems. Specifically, we consider models with 3D planar subsystem symmetry, and show that these can realize subsystem symmetry protected topological phases with gapless boundary modes. Gauging the planar subsystem symmetry leads to a fracton order in which particles restricted to move along lines exhibit a new type of statistical interaction that is specific to the lattice geometry. We show that both the gapless boundary modes of the ungauged theory, and the statistical interactions after gauging, are naturally captured by a higher-rank version of Chern–Simons theory. We also show that gauging only part of the subsystem symmetry can lead to symmetry-enriched fracton orders, with quasiparticles carrying fractional symmetry charge.
Spectral Evolution of Long Gamma-ray Burst Prompt Emission: Electrostatic Acceleration and Adiabatic Expansion

Despite the great variation in the light curves of gamma-ray burst (GRB) prompt emission, their spectral energy distribution (SED) is generally curved and broadly peaked. In particular, their spectral evolution is well described by the hardness-intensity correlation during a single pulse decay phase, when the SED peak height S{sub p} decreases as its peak energy E{sub p} decreases. We propose an acceleration scenario, based on electrostatic acceleration, to interpret the E{sub p} distribution peak at {approx}0.25 MeV. We show that during the decay phase of individual pulses in the long GRB light curve, the adiabatic expansion losses likely dominate the synchrotron cooling effects. The energy loss as due to adiabatic expansion can also be used to describe the spectral evolution observed during their decay phase. The spectral evolution predicted by our scenario is consistent with that observed in single pulses of long BATSE GRBs.
An alternative resolution to the Mansuripur paradox

In 2013 an article published online by the journal Science declared that the paradox proposed by Masud Mansuripur was resolved. This paradox concerns a point charge-Amperian magnetic dipole system as seen in a frame of reference where they are at rest and one in which they are moving. In the latter frame an electric dipole appears on the magnetic dipole. A torque is then exerted upon the electric dipole by the point charge, a torque that is not observed in the at-rest frame. Mansuripur points out this violates the relativity principle and suggests the Lorentz force responsible for the torque be replaced by the Einstein–Laub force. The resolution of the paradox reported by Science, based on numerous papers in the physics literature, preserves the Lorentz force but depends on the concept of hidden momentum. Here I propose a different resolution based on the overlooked fact that the charge-magnetic dipole system contains linear and angular electromagnetic field momentum. The time rate of change of the field angular–momentum in the frame through which the system is moving cancels that due to the charge-electric dipole interaction. From this point of view hidden momentum is not needed in the resolution of the paradox.
Electrostatic guiding of the methylidyne radical at cryogenic temperatures

We have produced a cryogenic buffer-gas cooled beam of the diatomic molecular radical CH (methylidyne). This molecule is of interest for studying cold chemical reactions and fundamental physics measurements. Its light mass and ground-state structure make it a promising candidate for electrostatic guiding and Stark deceleration, which allows for control over its kinetic energy. This control can facilitate studies of reactions with tuneable collision energies and trapping for precise spectroscopic studies. Here, we have demonstrated electrostatic guiding of CH with fluxes up to 109 molecules per steradian per pulse.
Petz map and Python’s lunch

We look at the interior operator reconstruction from the point of view of Petz map and study its complexity. We show that Petz maps can be written as precursors under the condition of perfect recovery. When we have the entire boundary system its complexity is related to the volume/action of the wormhole from the bulk operator to the boundary. When we only have access to part of the system, Python’s lunch appears and its restricted complexity depends exponentially on the size of the subsystem one loses access to.
Stellar Populations at Large Redshifts

It is now possible to probe stellar populations at large lookback times. The Butcher-Oemler Effect in distant clusters is un-ambiguous evidence for unexpectedly recent evolution of disk galaxies in dense environments, probably through starbursts induced by interactions. Recent applications of the "red envelope" test at z ≲ 1 indicate that some luminous galaxies formed ∼ 10–13 Gyr ago.
On the formation of multiple concentric rings and gaps in protoplanetary disks

As spiral waves driven by a planet in a gaseous disk steepen into a shock, they deposit angular momentum, opening a gap in the disk. This has been well studied using both linear theory and numerical simulations, but so far, only for the primary spiral arm -- the one directly attached to the planet. Using two-dimensional hydrodynamic simulations, we show that the secondary and tertiary arms driven by a planet can also open gaps as they steepen into shocks. The depths of the secondary/tertiary gaps in surface density grow with time in a low viscosity disk ($\alpha = 5\times10^{-5}$), so even low-mass planets (e.g., super-Earth or mini-Neptune-mass) embedded in the disk can open multiple observable gaps, provided that sufficient time has passed. Applying our results to the HL Tau disk, we show that a single 30 Earth-mass planet embedded in the ring at 68.8~au (B5) can reasonably well reproduce the positions of the two major gaps at 13.2 and 32.3 au (D1 and D2), and roughly reproduce two other major gaps at 64.2 and 74.7 au (D5 and D6) seen in the mm continuum. The positions of secondary/tertiary gaps are found to be sensitive to the planetary mass and the disk temperature profile, so with accurate observational measurements of the temperature structure the positions of multiple gaps can be used to constrain the mass of the planet. We also comment on the gaps seen in the TW Hya and HD~163296 disk.
Optical Discovery of an Apparent Galactic Supernova Remnant G159.6+7.3

Deep Hα images of portions of a faint 3 ◦ × 4 ◦ Hα shell centered at l = 159. ◦ 6 ,b = 7. 3 seen on the Virginia Tech Spectral Line Survey images revealed the presence of several thin emission filaments along its eastern limb. Low-dispersion optical spectra of two of these filaments covering the wavelength range of 4500–7500 A show narrow Hα line emissions with velocities around −170 ± 30 km s −1 . Both the morphology and spectra of these filaments are consistent with a Balmer-dominated shock interpretation and we propose that these optical filaments indicate that the large Hα emission shell is a previously unrecognized supernova remnant (SNR). ROSAT All Sky Survey images indicate the possible presence of extremely faint, diffuse emission from the shell’s central region. The shell’s location more than 7 ◦ off the Galactic plane in a region of relatively low interstellar density may account for the lack of any reported associated non-thermal radio emissions. The rare discovery of a Galactic SNR at optical wavelengths suggests that additional high-latitude SNRs may have escaped radio and X-ray detection.
On permutation-twisted free fermions and two conjectures

We conjecture that the category of permutation-twisted modules for a multi-fold tensor product vertex operator superalgebra and a cyclic permutation of even order is isomorphic to the category of parity-twisted modules for the underlying vertex operator superalgebra. This conjecture is based on our observations of the cyclic permutation-twisted modules for free fermions as we discuss in this work, as well as previous work of the first author constructing and classifying permutation-twisted modules for tensor product vertex operator superalgebras and a permutation of odd order. In addition, we observe that the transposition isomorphism for two free fermions corresponds to a lift of the −1 isometry of the integral lattice vertex operator superalgebra corresponding to two free fermions under boson-fermion correspondence. We conjecture that all even order cyclic permutation automorphisms of free fermions can be realized as lifts of lattice isometries under boson-fermion correspondence. We discuss the role of parity stability in the construction of these twisted modules and prove that in general, parity-unstable weak twisted modules for a vertex operator superalgebras come in pairs that form orthogonal invariant subspaces of parity-stable weak twisted modules, clarifying their role in many other settings.
GeV─TeV Counterparts of SS 433/W50 from Fermi-LAT and HAWC Observations

The extended jets of the microquasar SS 433 have been observed in optical, radio, X-ray, and recently very-high-energy γ-rays by High Altitude Water Cerenkov (HAWC). The detection of HAWC γ-rays with energies as great as 25 TeV motivates searches for high-energy γ-ray counterparts in the Fermi-Large Area Telescope (LAT) data in the 100 MeV–300 GeV band. In this paper, we report on the first joint analysis of Fermi-LAT and HAWC observations to study the spectrum and location of γ-ray emission from SS 433. Our analysis finds common emission sites of GeV-to-TeV γ-rays inside the eastern and western lobes of SS 433. The total flux above 1 GeV is in both lobes. The γ-ray spectrum in the eastern lobe is consistent with inverse Compton emission by an electron population that is accelerated by jets. To explain both the GeV and TeV flux, the electrons need to have a soft intrinsic energy spectrum, or undergo a quick cooling process due to synchrotron radiation in a magnetized environment.
Global Bounds on Stable Polynomials

A classical inequality of Szasz bounds polynomials with no zeros in the upper half plane entirely in terms of their first few coefficients. Borcea–Branden generalized this result to several variables as a piece of their characterization of linear maps on polynomials preserving stability. In this paper, we use determinantal representations to prove Szasz type inequalities in two variables and then prove that one can use the two variable inequality to prove an inequality for several variables.
ON A RESIDUE REPRESENTATION OF DEFORMATION, KOSZUL AND CHIRAL RINGS

A residue-theoretic representation is given for massless matter fields in (quotients of) (weighted) Calabi-Yau complete intersection models and the corresponding chiral operators in Landau-Ginzburg orbifolds. The well-known polynomial deformations are thus generalized, and the universal but somewhat abstract Koszul computations acquire a concrete realization and a general but more heuristic reinterpretation. Also, a direct correspondence with a BRST type analysis of constrained systems emerges naturally.
The Bad Thing About Good Advice: Understanding When and How Advice Exacerbates Overconfidence

Much research on advice taking examines how people revise point estimates given input from others. This work has established that people often egocentrically discount advice. If they were to place ...
Statistical Modeling for Spatio-Temporal Data From Stochastic Convection-Diffusion Processes

This article proposes a physical-statistical modeling approach for spatio-temporal data arising from a class of stochastic convection-diffusion processes. Such processes are widely found in scienti...
A non-perturbative pairwise-additive analysis of charge transfer contributions to intermolecular interaction energies

Energy decomposition analysis (EDA) based on absolutely localized molecular orbitals (ALMOs) decomposes the interaction energy between molecules into physically interpretable components like geometry distortion, frozen interactions, polarization, and charge transfer (CT, also sometimes called charge delocalization) interactions. In this work, a numerically exact scheme to decompose the CT interaction energy into pairwise additive terms is introduced for the ALMO-EDA using density functional theory. Unlike perturbative pairwise charge-decomposition analysis, the new approach does not break down for strongly interacting systems, or show significant exchange-correlation functional dependence in the decomposed energy components. Both the energy lowering and the charge flow associated with CT can be decomposed. Complementary occupied-virtual orbital pairs (COVPs) that capture the dominant donor and acceptor CT orbitals are obtained for the new decomposition. It is applied to systems with different types of interactions including DNA base-pairs, borane-ammonia adducts, and transition metal hexacarbonyls. While consistent with most existing understanding of the nature of CT in these systems, the results also reveal some new insights into the origin of trends in donor-acceptor interactions.
Hierarchical Needs Based Self-Adaptive Framework For Cooperative Multi-Robot System

Research in multi-robot and swarm systems has seen significant interest in cooperation of agents in complex and dynamic environments. To effectively adapt to unknown environments and maximize the utility of the group, robots need to cooperate, share information, and make a suitable plan according to the specific scenario. Inspired by Maslow’s hierarchy of human needs and systems theory, we introduce Robot’s Need Hierarchy and propose a new solution called Self-Adaptive Swarm System (SASS). It combines multi-robot perception, communication, planning, and execution with the cooperative management of conflicts through a distributed Negotiation-Agreement Mechanism that prioritizes robot’s needs. We also decompose the complex tasks into simple executable behaviors through several Atomic Operations, such as selection, formation, and routing. We evaluate SASS through simulating static and dynamic tasks and comparing them with the state-of-the-art collision-aware task assignment method integrated into our framework.
Flexure updates to MOSFIRE on the Keck I telescope

We present a recent evaluation and updates applied to the Multi-Object Spectrometer For Infra-Red Exploration (MOSFIRE) on the Keck I telescope. Over the course of significantly long integrations, when MOSFIRE sits on one mask for >4 hours, a slight drift in mask stars has been measured. While this does not affect all science-cases done with MOSFIRE, the drift can smear out signal for observers whose science objective depends upon lengthy integrations. This effect was determined to be the possible result of three factors: the internal flexure compensation system (FCS), the guider camera flexure system, and/or the differential atmospheric refraction (DAR) corrections. In this work, we will summarize the three systems and walk through the current testing done to narrow down the possible culprit of this drift and highlight future testing to be done.
Visualizing and assessing US county-level COVID19 vulnerability.

Background Like most of the world, the United States’ public health and economy are impacted by the COVID19 pandemic. However, discrete pandemic effects may not be fully realized on the macro-scale. With this perspective, our goal is to visualize spread of the pandemic and measure county-level features which may portend vulnerability. Methods We accessed the New York Times GitHub repository COVID19 data and 2018 United States Census data for all United States Counties. The disparate datasets were merged and filtered to allow for visualization and assessments about case fatality rate (CFR%) and associated demographic, ethnic and economic features. Results Our results suggest that county-level COVID19 fatality rates are related to advanced population age (P Conclusions Unique COVID19 impacts are realized at the county level. Use of public datasets, data science skills and information visualization can yield helpful insights to drive understanding about community-level vulnerability.
On the contrast dependence of crowding

Visual clutter affects our ability to see. Objects that would be identifiable on their own may become unrecognizable when presented close together ("crowding"), but the psychophysical characteristics of crowding have resisted simplification. Image properties initially thought to produce crowding have paradoxically yielded unexpected results; for example, adding flanking objects can ameliorate crowding (Manassi, Sayim, & Herzog, 2012; Herzog, Sayim, Chcherov, & Manassi, 2015; Pachai, Doerig, & Herzog, 2016). The resulting theory revisions have been sufficiently complex and specialized as to make it difficult to discern what principles may underlie the observed phenomena. Here, a generalized formulation of simple visual contrast energy is presented, arising from straightforward analyses of center and surround neurons in the early visual stream. Extant contrast measures, such as root mean square contrast, are easily shown to fall out as reduced special cases. The new generalized contrast energy metric surprisingly predicts the principal findings of a broad range of crowding studies. These early crowding phenomena may thus be said to arise predominantly from contrast or are, at least, severely confounded by contrast effects. Note that these findings may be distinct from accounts of other, likely downstream, "configural" or "semantic" instances of crowding, suggesting at least two separate forms of crowding that may resist unification. The new fundamental contrast energy formulation provides a candidate explanatory framework that addresses multiple psychophysical phenomena beyond crowding.
Unified description of the coupled-channels and statistical Hauser-Feshbach nuclear reaction theories for low energy neutron incident reactions

We incorporate the coupled-channels optical model into the statistical Hauser-Feshbach nuclear reaction theory, where the scattering matrix is diagonalized by performing the Engelbrecht-Weidenmuller transformation. This technique has been implemented in the coupled-channels optical model code ECIS by J. Raynal, and we extend this method so that all the open channels in a nucleon-induced reaction on a deformed nucleus can be calculated consistently.
Genome-wide variation in DNA methylation linked to developmental stage and chromosomal suppression of recombination in white-throated sparrows.

Much of our knowledge on regulatory impacts of DNA methylation has come from laboratory-bred model organisms, which may not exhibit the full extent of variation found in wild populations. Here, we investigated naturally-occurring variation in DNA methylation in a wild avian species, the white-throated sparrow (Zonotrichia albicollis). This species offers exceptional opportunities for studying the link between genetic differentiation and phenotypic traits because of a non-recombining chromosome pair linked to both plumage and behavioral phenotypes. Using novel single-nucleotide resolution methylation maps and gene expression data, we show that DNA methylation and the expression of DNA methyltransferases are significantly higher in adults than in nestlings. Genes for which DNA methylation varied between nestlings and adults were implicated in development and cell differentiation and were located throughout the genome. In contrast, differential methylation between plumage morphs was concentrated in the non-recombining chromosome pair. Interestingly, a large number of CpGs on the non-recombining chromosome, localized to transposable elements, have undergone dramatic loss of DNA methylation since the split of the ZAL2 and ZAL2m chromosomes. Changes in methylation predicted changes in gene expression for both chromosomes. In summary, we demonstrate changes in genome-wide DNA methylation that are associated with development and with specific functional categories of genes in white-throated sparrows. Moreover, we observe substantial DNA methylation reprogramming associated with the suppression of recombination, with implications for genome integrity and gene expression divergence. These results offer an unprecedented view of ongoing epigenetic reprogramming in a wild population.
Blockade of LAG-3 in PD-L1-Deficient Mice Enhances Clearance of Blood Stage Malaria Independent of Humoral Responses

T cells expressing high levels of inhibitory receptors such as PD-1 and LAG-3 are a hallmark of chronic infections and cancer. Checkpoint blockade therapies targeting these receptors have been largely validated as promising strategies to restore exhausted T cell functions and clearance of chronic infections and tumors. The inability to develop long-term natural immunity in malaria-infected patients has been proposed to be at least partially accounted for by sustained expression of high levels of inhibitory receptors on T and B lymphocytes. While blockade or lack of PD-1/PD-L1 and/or LAG-3 was reported to promote better clearance of Plasmodium parasites in various mouse models, how exactly blockade of these pathways contributes to enhanced protection is not known. Herein, using the mouse model of non-lethal P. yoelii (Py) infection, we reveal that the kinetics of blood parasitemia as well as CD4+ T follicular helper (TFH) and germinal center (GC) B cell responses are indistinguishable between PD-1-/-, PD-L1-/- and WT mice. Yet, we also report that monoclonal antibody (mAb) blockade of LAG-3 in PD-L1-/- mice promotes accelerated control of blood parasite growth and clearance, consistent with prior therapeutic blockade experiments. However, neither CD4+ TFH and GC B cell responses, nor parasite-specific Ab serum titers and capacity to transfer protection differed. We also found that i) the majority of LAG-3+ cells are T cells, ii) selective depletion of CD4+ but not CD8+ T cells prevents anti-LAG-3-mediated protection, and iii) production of effector cytokines by CD4+ T cells is increased in anti-LAG-3-treated versus control mice. Thus, taken together, these results are consistent with a model in which blockade and/or deficiency of PD-L1 and LAG-3 on parasite-specific CD4+ T cells unleashes their ability to effectively clear blood parasites, independently from humoral responses.
Zivotofsky II's Two Visions for Foreign Relations Law

The five opinions in Zivotofsky v. Kerry – four by the Supreme Court’s Republican-nominated Justices – exposed fault-lines over foreign relations law that have remained hidden in many of the Court’s other cases. This short essay, part of an AJIL Unbound Agora on the case, explores the most notable of these fissures – that between Justice Kennedy, who wrote the majority opinion, and Chief Justice Roberts, who dissented. Their disagreement in this case highlights the two Justices’ very different visions of U.S. foreign relations law and reveals the dynamic that has defined the direction of the Court over the last ten years. The relationship between Justice Kennedy and Chief Justice Roberts has been the fulcrum on which the Court’s foreign relations opinions and posture has turned and is likely to turn for some time to come.
Procedural Fairness in Election Contests

INTRODUCTION 1 I. ELECTION CONTESTS BY TYPE OF ELECTION 5 A. ELECTION CONTESTS INVOLVING STATE LEGISLATIVE OFFICES 5 B. ELECTION CONTESTS INVOLVING GOVERNOR AND LIEUTENANT GOVERNOR 9 C. ELECTION CONTESTS INVOLVING JUDICIAL ELECTIONS 20 D. ELECTION CONTESTS INVOLVING CONGRESSIONAL ELECTIONS 24 E. ELECTION CONTESTS INVOLVING PRESIDENTIAL ELECTORS 29 II. COMMON CHARACTERISTICS OF ELECTION CONTEST PROCEDURES 34 A. STATUTORY DEADLINES 34 B. SPECIFIC PROCEDURAL DETAILS REGARDING THE JUDICIAL PROCESS 36 C. APPELLATE REVIEW 41 III. REFORMING ELECTION CONTEST PROCEDURES: TIMING, STANDARDS, AND IMPARTIALITY 44 A. GOALS FOR RESOLVING ELECTION CONTESTS 44 B. IMPROVING ELECTION CONTEST PROCESSES 46 CONCLUSION 57 APPENDIX: SUMMARY OF STATUTORY PROCEDURES FOR CONTESTING ELECTIONS 58
The Implications of South African Economic Growth for the Rest of Africa

This paper measures the extent to which South African economic growth is an engine of growth in sub-Saharan Africa. Results based on panel data estimation for 47 African countries over four decades suggest that South African growth has a substantial positive impact on growth in the rest of Africa, even after controlling for other growth determinants. The estimates are robust to the effects of global and regional shocks, changes in model specification, and sample period.
Assessing Public Health Strategies for Advancing Child Protection: Human Trafficking as a Case Study

Ensuring the well-being of all children is one of the great challenges of our time. Despite concerted efforts in the United States to protect children, research reveals that millions of children suffer harm each year. Frequently, when policymakers and child advocates speak of “child protection,” they focus primarily on abuse and neglect in the home. Often, child protection does not contemplate violence against children in the community. The inside/outside-the-home divide is somewhat of a false dichotomy, however, as the two realms are interrelated. Children who suffer abuse and neglect in the home are frequently at heightened risk of exploitation outside the home. This symposium essay focuses on the community-based issues of trafficking and commercial sexual exploitation of children, with a view to elucidating the merits of public health approaches to harm against children. Trafficking and commercial sexual exploitation of children are significant issues in the United States. This essay briefly outlines the current framework for responding to child trafficking. It then discusses what a public health approach could add to antitrafficking efforts. Finally, this essay seeks to draw lessons from a public health approach to child trafficking that might inform child protection strategies more broadly.
Interior-Point-Based Online Stochastic Bin Packing

Bin packing is an algorithmic problem that arises in diverse applications such as remnant inventory systems, shipping logistics, and appointment scheduling. In its simplest variant, a sequence of T items (e.g., orders for raw material, packages for delivery) is revealed one at a time, and each item must be packed on arrival in an available bin (e.g., remnant pieces of raw material in inventory, shipping containers). The sizes of items are i.i.d. samples from an unknown distributions, but the sizes are known when the items arrive. The goal is to minimize the number of non­empty bins (equivalently waste, defined to be the total unused space in non­empty bins). This problem has been extensively studied in the Operations Research and Theoretical Computer Science communities, yet all existing heuristics either rely on learning the distribution or exhibit ​o(T) additive suboptimality compared to the optimal offline algorithm only for certain classes of distributions (those with sublinear optimal expected waste). In this paper, we propose a family of algorithms which are the first truly distribution-­oblivious algorithms for stochastic bin packing, and achieve ​O(√T) additive suboptimality for all item size distributions. Our algorithms are inspired by approximate interior­-point algorithms for convex optimization. In addition to regret guarantees for i.i.d. sequences, we also prove a family of novel regret bounds for general non­i.i.d. input sequences, including guarantees for locally adversarially perturbed i.i.d. sequences. To the best of our knowledge these are the first such results for non-­i.i.d. and non­-random-­permutation input sequences for online stochastic packing.
Stoking the fires? CO2 emissions and economic growth

Abstract We examine the relationship between economic development and carbon dioxide emissions, a greenhouse gas central to global warming predictions. Estimates derived from global panel data suggest a diminishing marginal propensity to emit (MPE) carbon dioxide as GDP per capita rises. Despite this, global carbon dioxide emissions growth will continue at 1.8 percent per annum for the foreseeable future, a result that is not sensitive to average output growth. Instead, emissions growth continues because output and population will grow most rapidly in lower-income nations with high MPEs. This latter feature emphasizes the distributional consequences of policies to reduce emissions.
Cross-Sectional Return Dispersion and Time Variation in Value and Momentum Premiums

We find that the market’s recent cross-sectional dispersion in stock returns is positively related to the subsequent value book-to-market premium and negatively related to the subsequent momentum premium. The partial relation between return dispersion (RD) and the subsequent value and momentum premiums remains strong when controlling for macroeconomic state variables suggested by the literature. Our findings are consistent with recent theoretical insights and empirical evidence that suggest that the market’s RD may serve as a leading countercyclical state variable, that the value premium is countercyclical, and that the momentum premium is procyclical.
Searching for the (dark) forces behind protection

that may lead politicians to value rents differently across industries. The idea is motivated by the puzzling results of the recent empirical work on the GrossmanHelpman model. The empirical work in the paper based on US data confirms that lobby contributions do not play obvious roles in trade policy. Rather, trade policies seem to be placing higher weights on the earnings of industries where lower skill workers and smaller, less capital intensive firms are more prevalent. It is argued that this can be explained by the credit and insurance constraints that such agents tend to face. The weakness of lobby contributions in predicting protectionism across industries may be due to the variety of alternative goals that lobbies pursue and the diversity of interests within each industry. Also, the industries with well-organized and well-funded lobbies may have easier access to more efficient fiscal and financial transfers. The approach adopted in this paper paves the way for examining a variety of determinants of trade policy in a broader framework. The regularities observed here have farreaching implications for the pattern and evolution of trade policies.
Insurance Rationing versus Public Political Rationing: The Case of the Oregon Health Plan

This article describes the development and evolution of the Oregon experiment with public political rationing in health care. As dissatisfaction with current health care rationing has mounted, the search has accelerated for alternatives to replace the de facto rationing generated by the private health insurance marketplace. As the foremost example of public rationing, the closely-watched Oregon Health Plan is widely offered as an alternative to traditional private health insurance. Other health care rationing alternatives include health maintenance organizations (HMOs) and proposals that encourage self-rationing by individual consumers.
Intraschool variation in class size: patterns and implications.

Economists attempting to explain the widening of the black-white wage gap in the late 1970s by differences in school quality have been faced with the problem that recent data reveal virtually no gap in the quality of schools attended by blacks and whites using a variety of measures. In this paper we re-examine racial differences in school quality. We begin by considering the effects of using the pupil-teacher ratio rather than the schools average class size in an education production function since the pupil-teacher ratio is a rough proxy at best. Second we consider the importance of using actual class size rather than school-level measures of class size. We find that while the pupil-teacher ratio and average class size are correlated the pupil-teacher ratio is systematically less than or equal to the average class size. Mathematically part of the difference is due to the intraschool allocation of teachers to classes. As a result while the pupil-teacher ratio suggests no black-white differences in class size measures of the schools average class size suggest that blacks are in larger classes. Further the two measures result in differing estimates of the importance of class size in an education production function. We also conclude that school level measures may obscure important within-school variation in class size due to the small class sizes for compensatory education. Since black students are more likely to be assigned to compensatory education classes a kind of aggregation bias results. We find that not only are blacks in schools with larger average class sizes but they are also in larger classes within schools conditional on class type. The intraschool class size patterns suggest that using within-school variation in education production functions is not a perfect solution to aggregation problems because of non-random assignment of students to classes of differing sizes. However once the selection problem has been addressed it appears that smaller classes at the eighth grade lead to larger test score gains from eighth to tenth grade and that differences in class size can explain approximately 15 percent of the black-white difference in educational achievement. (authors)
THE GREAT TRADE COLLAPSE: AN EVALUATION OF COMPETING STORIES

The reduction in international trade has been more than the reduction in economic activity during the 2008 financial crisis, against the one-to-one relationship between them implied by standard trade models. This so-called the Great Trade Collapse (GTC) has been investigated extensively in the literature resulting in alternative competing stories as potential explanations. By introducing and estimating a dynamic stochastic general equilibrium model using 18 quarterly series from the USA, including those that represent the competing stories, this paper evaluates the contribution of each story to GTC. The results show that retail inventories have contributed the most to the collapse and the corresponding recovery, followed by protectionist policies, intermediate-input trade, and trade finance. Productivity and demand shocks have played negligible roles.
The Effect of Imposed Voting Requirements on FASB Decisions

To issue an accounting standard, members of the Financial Accounting Standards Board (FASB) must approve pronouncements with a majority. Since its inception, the FASB has been subjected to two types of voting requirements: a simple majority, which requires the approval of four of seven members, or a supermajority, which requires the approval of five of seven members. This study investigates the effects of different voting requirements on (1) the time taken to generate a pronouncement and (2) the need for subsequent revision of the accounting pronouncement.The results indicate that the supermajority voting requirement hinders the pronouncement generation process. This is evidenced by a decrease in the frequency of pronouncements issued and an increase in the amount of time required to generate an accounting pronouncement. In addition, the supermajority was found to have no effect on subsequent interpretation or supersedure of the pronouncement. As a result, the findings provide limited justification for th...