cssi/SciSciGPT-SciSciNet huggingface dataset:
Horizonless, singularity-free, compact shells satisfying NEC

Gravitational collapse singularities are undesirable, yet inevitable to a large extent in General Relativity. When matter satisfying null energy condition (NEC) collapses to the extent a closed trapped surface is formed, a singularity is inevitable according to Penrose’s singularity theorem. Since positive mass vacuum solutions are generally black holes with trapped surfaces inside the event horizon, matter cannot collapse to an arbitrarily small size without generating a singularity. However, in modified theories of gravity where positive mass vacuum solutions are naked singularities with no trapped surfaces, it is reasonable to expect that matter can collapse to an arbitrarily small size without generating a singularity. Here we examine this possibility in the context of a modified theory of gravity with torsion in an extra dimension. We study singularity-free static shell solutions to evaluate the validity of NEC on the shell. We find that with sufficiently high pressure, matter can be collapsed to arbitrarily small size without violating NEC and without producing a singularity.
Determination of the crystal structures of In70-Ni30 and In70-Pd30 using perturbed angular correlation

According to phase diagrams based on x-ray measurements, In70-Pt30 has the cubic Sn7Ir3 crystal structure (D8f, cI40) but the alloys In70-Ni30 and In70-Pd30 have been variously reported to have either a cubic gamma-brass (D81 − 3, cI52) or the Sn7Ir3 structures. In this study, hyperfine interaction measurements are applied as an alternate method to identify phases. Perturbed angular correlation (PAC) measurements were made of characteristic nuclear quadrupole interactions of 111In/Cd probe atoms, and demonstrated a common, characteristic “signature” of the Sn7Ir3 structure in all three alloys. The Sn7Ir3 structure has two inequivalent Sn-sites with a 3:4 ratio of atoms and point symmetries indicate that the electric-field gradients at both sites should be axially symmetric. Measured perturbation functions for all three alloys exhibited two axially symmetric quadrupole interaction signals having the expected 3:4 ratio of amplitudes, as expected for the structure. Furthermore, ratios of the two quadrupole interaction frequencies in each alloy were characteristically large, with frequencies for probe atoms on In(3) sites roughly five times greater than on In(4) sites. Taken together, these observations confirm that all three phases have the Sn7Ir3 structure. Quadrupole interaction frequencies are also reported for isostructural alloys of gallium with Pt, Pd and Ni. Negligible inhomogeneous broadening was observed in measurements near room temperature in all six phases, indicating excellent atomic ordering at the stoichiometric 70:30 compositions.
PrIU: A Provenance-Based Approach for Incrementally Updating Regression Models

The ubiquitous use of machine learning algorithms brings new challenges to traditional database problems such as incremental view update. Much effort is being put in better understanding and debugging machine learning models, as well as in identifying and repairing errors in training datasets. Our focus is on how to assist these activities when they have to retrain the machine learning model after removing problematic training samples in cleaning or selecting different subsets of training data for interpretability. This paper presents an efficient provenance-based approach, PrIU, and its optimized version, PrIU-opt, for incrementally updating model parameters without sacrificing prediction accuracy. We prove the correctness and convergence of the incrementally updated model parameters, and validate it experimentally. Experimental results show that up to two orders of magnitude speed-ups can be achieved by PrIU-opt compared to simply retraining the model from scratch, yet obtaining highly similar models.
Sequentially Congruent Partitions and Related Bijections

We study a curious class of partitions, the parts of which obey an exceedingly strict congruence condition we refer to as “sequential congruence”: the mth part is congruent to the (m+1)th part modulo m, with the smallest part congruent to zero modulo the length of the partition. It turns out these obscure-seeming objects are embedded in a natural way in the theory of partitions. We show that sequentially congruent partitions with the largest part n are in bijection with the partitions of n. Moreover, we show sequentially congruent partitions induce a bijection between partitions of n and partitions of length n whose parts obey a strict “frequency congruence” condition—the frequency (or multiplicity) of each part is divisible by that part—and prove families of similar bijections, connecting with G. E. Andrews’ theory of partition ideals.
DAHA and plane curve singularities

We suggest a relatively simple and totally geometric conjectural description of uncolored daha superpolynomials of arbitrary algebraic knots (conjecturally coinciding with the reduced stable Khovanov–Rozansky polynomials) via the flagged Jacobian factors (new objects) of the corresponding unibranch plane curve singularities. This generalizes the Cherednik–Danilenko conjecture on the Betti numbers of Jacobian factors, the Gorsky combinatorial conjectural interpretation of superpolynomials of torus knots and that by Gorsky and Mazin for their constant term. The paper mainly focuses on nontorus algebraic knots. A connection with the conjecture due to Oblomkov, Rasmussen and Shende is possible, but our approach is different. A motivic version of our conjecture is related to p –adic orbital A –type integrals for anisotropic centralizers.
On Transport Properties of Isotropic Quasiperiodic XY Spin Chains

We consider isotropic XY spin chains whose magnetic potentials are quasiperiodic and the effective one-particle Hamiltonians have absolutely continuous spectra. For a wide class of such XY spin chains, we obtain lower bounds on their Lieb–Robinson velocities \({\mathfrak{v}}\) in terms of group velocities of their effective Hamiltonians: $$\mathfrak{v}{\geqslant} {\mathop {\rm ess sup}_{[0,1]}}\frac{2}{\pi}\frac{dE}{dN}.$$ where E is considered as a function of the integrated density of states.
Scattering concentration bounds: brightness theorems for waves

The brightness theorem—brightness is nonincreasing in passive systems—is a foundational conservation law, with applications ranging from photovoltaics to displays, yet it is restricted to the field of ray optics. For general linear wave scattering, we show that power per scattering channel generalizes brightness, and we derive power-concentration bounds for systems of arbitrary coherence. The bounds motivate a concept of “wave etendue” as a measure of incoherence among the scattering-channel amplitudes and which is given by the rank of an appropriate density matrix. The bounds apply to nonreciprocal systems that are of increasing interest, and we demonstrate their applicability to maximal control in nanophotonics, for metasurfaces and waveguide junctions. Through inverse design, we discover metasurface elements operating near the theoretical limits.
2018 update of the discoveries of nuclides

The 2018 update of the discovery of nuclide project is presented. Fifty new nuclides were observed for the first time in 2018. A large number of isotopes are still only published in conference proc...
Quantum Computation and Quantum Information

Quantum computation and quantum information are of great current interest in computer science, mathematics, physical sciences and engineering. They will likely lead to a new wave of technological innovations in communication, computation and cryptography. As the theory of quantum physics is fundamentally stochastic, randomness and uncertainty are deeply rooted in quantum computation, quantum simulation and quantum information. Consequently quantum algorithms are random in nature, and quantum simulation utilizes Monte Carlo techniques extensively. Thus statistics can play an important role in quantum computation and quantum simulation, which in turn offer great potential to revolutionize computational statistics. While only pseudo-random numbers can be generated by classical computers, quantum computers are able to produce genuine random numbers; quantum computers can exponentially or quadratically speed up median evaluation, Monte Carlo integration and Markov chain simulation. This paper gives a brief review on quantum computation, quantum simulation and quantum information. We introduce the basic concepts of quantum computation and quantum simulation and present quantum algorithms that are known to be much faster than the available classic algorithms. We provide a statistical framework for the analysis of quantum algorithms and quantum simulation.
Disordered topological insulators via C*-algebras

The theory of almost commuting matrices can be used to quantify topological obstructions to the existence of localized Wannier functions with time-reversal symmetry in systems with time-reversal symmetry and strong spin-orbit coupling. We present a numerical procedure that calculates a Z2 invariant using these techniques, and apply it to a model of HgTe. This numerical procedure allows us to access sizes significantly larger than procedures based on studying twisted boundary conditions. Our numerical results indicate the existence of a metallic phase in the presence of scattering between up and down spin components, while there is a sharp transition when the system decouples into two copies of the quantum Hall effect. In addition to the Z2 invariant calculation in the case when up and down components are coupled, we also present a simple method of evaluating the integer invariant in the quantum Hall case where they are decoupled.
Response of Circumnuclear Water Masers to Luminosity Changes in an Active Galactic Nucleus

Circumnuclear water masers can respond in two ways to changes in the luminosity of an active galactic nucleus. First, an increase in the X-ray luminosity can lead to an increase in the maser emissivity, and second, an increase in the intrinsic bolometric luminosity may result in a temporary decrease in the difference between the gas and dust temperature and a consequent decrease in the maser output. While the latter effect can occur over a period shorter than the thermal timescale, the former effect cannot. Quantitative estimates of the response of the water maser emissivity to changes in either the X-ray or bolometric luminosity are presented, together with estimates of the relevant timescales. Either mechanism could account for recent observations by Gallimore et al. suggesting that the water maser variability in two widely separated regions of the circumnuclear gas in NGC 1068 have been coordinated by a signal from the active nucleus. For either mechanism, a minimum H2 density of ~108 cm-3 is needed to explain the observed variability timescale.
Is the Young Star RZ Piscium Consuming Its Own (Planetary) Offspring

The erratically variable star RZ Piscium (RZ Psc) displays extreme optical dropout events and strikingly large excess infrared emission. To ascertain the evolutionary status of this intriguing star, we obtained observations of RZ Psc with the European Space Agency's X-ray Multi-Mirror Mission (XMM-Newton), as well as high-resolution optical spectroscopy with the Hamilton Echelle on the Lick Shane 3 m telescope and with HIRES on the Keck I 10 m telescope. The optical spectroscopy data demonstrate that RZ Psc is a pre-main sequence star with an effective temperature of 5600 $\pm$ 75 K and log g of 4.35 $\pm$ 0.10. The ratio of X-ray to bolometric luminosity, log L$_{X}$/L$_{bol}$, lies in the range -3.7 to -3.2, consistent with ratios typical of young, solar-mass stars, thereby providing strong support for the young star status of RZ Psc. The Li absorption line strength of RZ Psc suggests an age in the range 30-50 Myr, which in turn implies that RZ Psc lies at a distance of $\sim$170 pc. Adopting this estimated distance, we find the Galactic space velocity of RZ Psc to be similar to the space velocities of stars in young moving groups near the Sun. Optical spectral features indicative of activity and/or circumstellar material are present in our spectra over multiple epochs, which provide evidence for the presence of a significant mass of circumstellar gas associated with RZ Psc. We suggest that the destruction of one or more massive orbiting bodies has recently occurred within 1 au of the star, and we are viewing the aftermath of such an event along the plane of the orbiting debris.
Hybrid inverse problems for a system of Maxwell’s equations

This paper concerns the quantitative step of the medical imaging modality thermo-acoustic tomography (TAT). We model the radiation propagation by a system of Maxwell?s equations. We show that the index of refraction of light and the absorption coefficient (conductivity) can be uniquely and stably reconstructed from a sufficiently large number of TAT measurements. Our method is based on verifying that the linearization of the inverse problem forms a redundant elliptic system of equations. We also observe that the reconstructions are qualitatively quite different from the setting where radiation is modeled by a scalar Helmholtz equation as in Bal G et al (2011 Inverse Problems 27 055007).
Absorption of a particle by a rotating black hole: The potential barrier

For a test particle approaching a rapidly rotating black hole we find a range of values of the particle’s energy and angular momentum, on the order of 1% or more of the corresponding values of the hole, such that three conditions are satisfied. (1) The particle can reach the horizon. (2) After absorption the new hole still has a horizon. (3) The area of the new hole is less than the area of the original one, in apparent violation of a theorem of Hawking. We offer support for the claim that the test particle approximation is the cause of the violation.
Markovian dynamics on complex reaction networks

Abstract Complex networks, comprised of individual elements that interact with each other through reaction channels, are ubiquitous across many scientific and engineering disciplines. Examples include biochemical, pharmacokinetic, epidemiological, ecological, social, neural, and multi-agent networks. A common approach to modeling such networks is by a master equation that governs the dynamic evolution of the joint probability mass function of the underlying population process and naturally leads to Markovian dynamics for such process. Due however to the nonlinear nature of most reactions and the large size of the underlying state-spaces, computation and analysis of the resulting stochastic population dynamics is a difficult task. This review article provides a coherent and comprehensive coverage of recently developed approaches and methods to tackle this problem. After reviewing a general framework for modeling Markovian reaction networks and giving specific examples, the authors present numerical and computational techniques capable of evaluating or approximating the solution of the master equation, discuss a recently developed approach for studying the stationary behavior of Markovian reaction networks using a potential energy landscape perspective, and provide an introduction to the emerging theory of thermodynamic analysis of such networks. Three representative problems of opinion formation, transcription regulation, and neural network dynamics are used as illustrative examples.
Oscillating supertubes and neutral rotating black hole microstates

The construction of neutral black hole microstates is an important problem, with implications for the information paradox. In this paper we conjecture a construction of non-supersymmetric supergravity solutions describing D-brane configurations which carry mass and angular momentum, but no other conserved charges. We first study a classical string solution which locally carries dipole winding and momentum charges in two compact directions, but globally carries no net winding or momentum charge. We investigate its backreaction in the D1-D5 duality frame, where this object becomes a supertube which locally carries oscillating dipole D1-D5 and NS1-NS5 charges, and again carries no net charge. In the limit of an infinite straight supertube, we find an exact supergravity solution describing this object. We conjecture that a similar construction may be carried out based on a class of two-charge non-supersymmetric D1-D5 solutions. These results are a step towards demonstrating how neutral black hole microstates may be constructed in string theory.
Universality of Phase Transition Dynamics: Topological Defects from Symmetry Breaking

In the course of a nonequilibrium continuous phase transition, the dynamics ceases to be adiabatic in the vicinity of the critical point as a result of the critical slowing down (the divergence of the relaxation time in the neighborhood of the critical point). This enforces a local choice of the broken symmetry and can lead to the formation of topological defects. The Kibble–Zurek mechanism (KZM) was developed to describe the associated nonequilibrium dynamics and to estimate the density of defects as a function of the quench rate through the transition. During recent years, several new experiments investigated the formation of defects in phase transitions induced by a quench both in classical and quantum mechanical systems. At the same time, some established results were called into question. We review and analyze the Kibble–Zurek mechanism focusing in particular on this surge of activity, and suggest possible directions for further progress.
A complete analytic gravitational wave model for undergraduates

Gravitational waves are produced by orbiting massive binary objects, such as black holes and neutron stars, and propagate as ripples in the very fabric of spacetime. As the waves carry off orbital energy, the two bodies spiral into each other and eventually merge. They are described by Einstein's equations of General Relativity. For the early phase of the orbit, called the inspiral, Einstein equations can be linearized and solved through analytical approximations, while for the late phase, near the merger, we need to solve the fully nonlinear Einstein's equations on supercomputers. In order to recover the gravitational wave for the entire evolution of the binary, a match is required between the inspiral and the merger waveforms. Our objectives are to establish a streamlined matching method, that will allow an analytical calculation of the complete gravitational waveform, while developing a gravitational wave modeling tutorial for undergraduate physics students. We use post-Newtonian (PN) theory for the inspiral phase, which offers an excellent training ground for students, and rely on Mathematica for our calculations, a tool easily accessible to undergraduates. For the merger phase we bypass Einstein's equations by using a simple analytic toy model named the Implicit Rotating Source (IRS). After building the inspiral and merger waveforms, we construct our matching method and validate it by comparing our results with the waveforms for the first detection, GW150914, available as open-source. Several future projects can be developed based from this project: building complete waveforms for all the detected signals, extending the post-Newtonian model to take into account non-zero eccentricity, employing and testing a more realistic analytic model for the merger, building a separate model for the ringdown, and optimizing the matching technique.
THE BINARY FRACTION OF LOW-MASS WHITE DWARFS

We describe spectroscopic observations of 21 low-mass (≤0.45 M ☉) white dwarfs (WDs) from the Palomar-Green survey obtained over four years. We use both radial velocities and infrared photometry to identify binary systems, and find that the fraction of single, low-mass WDs is ≤30%. We discuss the potential formation channels for these single stars including binary mergers of lower-mass objects. However, binary mergers are not likely to explain the observed number of single low-mass WDs. Thus, additional formation channels, such as enhanced mass loss due to winds or interactions with substellar companions, are likely.
Constraining domain wall dark matter with a network of superconducting gravimeters and LIGO

There is strong astrophysical evidence that dark matter (DM) makes up some 27% of all mass in the universe. Yet, beyond gravitational interactions, little is known about its properties or how it may connect to the Standard Model. Multiple frameworks have been proposed, and precision measurements at low energy have proven useful to help restrict the parameter space for many of these models. One set of models predicts that DM is a scalar field that “clumps” into regions of high local density, rather than being uniformly distributed throughout the galaxy. If this DM field couples to a Standard Model field, its interaction with matter can be thought of as changing the effective values of fundamental constants. One generic consequence of time variation of fundamental constants (or their spatial variation as the Earth passes through regions of varying density) is the presence of an anomalous, composition-dependent acceleration. Here we show how this anomalous acceleration can be measured using superconducting accelerometers, and demonstrate that > 20 years of archival data from the International Geodynamics and Earth Tide Services (IGETS) network can be utilized to set new bounds on these models. Furthermore, we show how LIGO and other gravitational wave detectors can be used as exquisitely sensitive probes for narrow ranges of the parameter space. While limited to DM models that feature spatial gradients, these two techniques complement the networks of precision measurement devices already in use for direct detection and identification of dark matter.
Metal Abundances of KISS Galaxies. I. Coarse Metal Abundances and the Metallicity-Luminosity Relation

We derive metal abundance estimates for a large sample of starbursting emission-line galaxies (ELGs). Our sample is drawn from the KPNO International Spectroscopic Survey (KISS), which has discovered over 2000 ELG candidates to date. Follow-up optical spectra have been obtained for ~900 of these objects. A three-step process is used to obtain metal abundances for these galaxies. We first calculate accurate nebular abundances for 12 galaxies whose spectra cover the full optical region from [O II] λλ3726, 3729 to beyond [S II] λλ6717, 6731 and include detection of [O III] λ4363. Using secondary metallicity indicators R23 and p3, we calculate metallicities for an additional 59 galaxies with spectra that cover a similar wavelength range but lack [O III] λ4363. The results are used to calibrate relations between metallicity and two readily observed emission-line ratios, which allow us to estimate coarse metallicities for 519 galaxies in total. The uncertainty in these latter abundance estimates is 0.16 dex. From the large, homogeneously observed sample of star-forming galaxies, we identify low-metallicity candidates for future study and investigate the metallicity-luminosity relation. We find a linear metallicity-luminosity relation of the form 12 + log(O/H) = 4.059 - 0.240MB, with an rms scatter of 0.252. This result implies that the slope of the metallicity-luminosity relation is steeper than when dwarf galaxies are considered alone and may be evidence that the relationship is not linear over the full luminosity range of the sample.
ASPECTS OF EXACTLY SOLVABLE QUANTUM-CORRECTED 2D DILATON GRAVITY THEORIES

After reviewing the basic aspects of the exactly solvable quantum-corrected dilaton gravity theories in two dimensions, we discuss a (subjective) selection of other aspects: (a) supersymmetric extensions, (b) the canonical formalism, ADM mass and the functional integral measure, and (c) a positive energy theorem and its application to the ADM and Bondi masses.
Investigating nearby exoplanets via interstellar radar

Interstellar radar is a potential intermediate step between passive observation of exoplanets and interstellar exploratory missions. Compared with passive observation, it has the traditional advantages of radar astronomy. It can measure surface characteristics, determine spin rates and axes, provide extremely accurate ranges, construct maps of planets, distinguish liquid from solid surfaces, find rings and moons, and penetrate clouds. It can do this even for planets close to the parent star. Compared with interstellar travel or probes, it also offers significant advantages. The technology required to build such a radar already exists, radar can return results within a human lifetime, and a single facility can investigate thousands of planetary systems. The cost, although too high for current implementation, is within the reach of Earth's economy.
Directly Observing the Galaxies Likely Responsible for Reionization

We report a new analysis of the Hubble Frontier Fields clusters Abell 2744 and MACS 0416 using wavelet decomposition to remove the cluster light, enabling the detection of highly magnified (>50x) galaxies a factor of 10x fainter in luminosity than previous studies. We find 167 galaxies at z > 6, and with this sample we are able to characterize the UV luminosity function to M_UV = -12.5 at z ~ 6, -14 at z ~ 7 and -15 at z ~ 8. We find a steep faint-end slope (alpha 6, consistent with the number of faint galaxies needed to reionize the Universe under standard assumptions.
Gravitational radiation from color-kinematics duality

We perturbatively calculate classical radiation in Yang-Mills theory and dilaton gravity, to next-to-leading order in couplings. The radiation is sourced by the scattering of two relativistic massive scalar sources with the dynamical effect taken into account, corresponding to the post-Minkowskian regime in gravity. We show how to arrange the Yang-Mills radiation such that the duality between color and kinematics is manifest, including the three-term Jacobi identity. The search for duality-satisfying expressions exploits an auxiliary bi-adjoint scalar theory as a guide for locality. The double copy is obtained by replacing the color factors in Yang-Mills with kinematic counterparts, following Bern-Carrasco-Johansson construction in S-matrix. On the gravity side, the radiation is directly computed at the third post-Minkowskian order with massive sources. We find perfect agreement between observables in dilaton gravity and the Yang-Mills double copy. This non-trivially generalizes the leading-order rules by Goldberger and Ridgway. For the first time, the kinematic Jacobi identity appears beyond field-theory S-matrix, suggesting that the color-kinematics duality holds more generally. Our results offer a path for simplifying analytical calculations in post-Minkowskian regime.
Multi-agent Q-learning of channel selection in multi-user cognitive radio systems: A two by two case

Resource allocation is an important issue in cognitive radio systems. It can be done by carrying out negotiation among secondary users. However, significant overhead may be incurred by the negotiation since the negotiation needs to be done frequently due to the rapid change of primary users' activity. In this paper, a channel selection scheme without negotiation is considered for multi-user and multi-channel cognitive radio systems. To avoid collision incurred by non-coordination, each secondary user learns how to select channels according to its experience. Multi-agent reinforcement leaning (MARL) is applied in the framework of Q-learning by considering opponent secondary users as a part of the environment. The dynamics of the Q-learning are illustrated using Metrick-Polak plot. A rigorous proof of the convergence of Q-learning is provided via the similarity between the Q-learning and Robinson-Monro algorithm, as well as the analysis of convergence of the corresponding ordinary differential equation (via Lyapunov function). Examples are illustrated and the performance of learning is evaluated by numerical simulations.
Ground-Edge-Based LIDAR Localization Without a Reflectivity Calibration for Autonomous Driving

In this work, we propose an alternative formulation to the problem of ground reflectivity grid-based localization involving laser-scanned data from multiple LIDARs mounted on autonomous vehicles. The driving idea of our localization formulation is an alternative edge reflectivity grid representation, which is invariant to laser source, angle of incidence, range, and robot surveying motion. Such a property eliminates the need of the postfactory reflectivity calibration whose time requirements are infeasible in mass-produced robots/vehicles. Our experiments demonstrate that we can achieve better performance than state of the art on ground reflectivity inference-map-based localization at no additional computational burden.
Improving sequencing by tunneling with multiplexing and cross-correlations

Sequencing by tunneling is a next-generation approach to read single-base information using electronic tunneling transverse to the single-stranded DNA (ssDNA) backbone while the latter is translocated through a narrow channel. The original idea considered a single pair of electrodes to read out the current and distinguish the bases [1, 2]. Here, we propose an improvement to the original sequencing by tunneling method, in which $$N$$ N pairs of electrodes are built in series along a synthetic nanochannel. While the ssDNA is forced through the channel using a longitudinal field it passes by each pair of electrodes for long enough time to gather a minimum of $$m$$ m tunneling current measurements, where $$m$$ m is determined by the level of sequencing error desired. Each current time series for each nucleobase is then cross-correlated together, from which the DNA bases can be distinguished. We show using random sampling of data from classical molecular dynamics, that indeed the sequencing error is significantly reduced as the number of pairs of electrodes, $$N$$ N , increases. Compared to the sequencing ability of a single pair of electrodes, cross-correlating $$N$$ N pairs of electrodes exponentially improves this sequencing ability due to the approximate log-normal nature of the tunneling current probability distributions. We have also used the Fenton---Wilkinson approximation to analytically describe the mean and variance of the cross-correlations that are used to distinguish the DNA bases. The method we suggest is particularly useful when the measurement bandwidth is limited, allowing a smaller electrode gap residence time while still promising to consistently identify the DNA bases correctly.
Comparison of Patient Satisfaction Between Virtual Visits During the COVID-19 Pandemic and In-person Visits Pre-pandemic.

Objective:To compare the patient experience of a virtual otolaryngology clinic visit to an in-person visit, especially with its significantly increased implementation during the COVID-19 pandemic.M...
When Does Dispute Resolution Substitute for a Reputation System? Empirical Evidence from a Service Procurement Platform

We consider the role of online dispute resolution (ex-post guarantees of supplier quality) when they are introduced in the presence of an online reputation system (an ex-ante informational mechanism), in the context of online service procurement platforms. We argue that dispute resolution will reduce buyers’ reliance on reputation systems in their hiring decisions to varying extents, depending on the nature of the work required. We assess these predictions using proprietary data capturing projects, service providers, bids, and hiring decisions around a natural experiment: the introduction of a new dispute resolution system at a major online service procurement platform. We provide evidence consistent with our expectations; introducing a dispute resolution system led buyers to reduce their consideration of service provider rating volumes in hiring decisions, particularly for projects where service provider performance could be evaluated objectively by a third-party (e.g., data entry, as opposed to more subjective, creative work, like logo design). We also report a variety of additional analyses, which demonstrate the robustness of our findings to alternative measures, dynamics of the effects depending on buyers’ experience with the dispute process, and the impact of the dispute service on buyers’ propensity to enter ratings of service providers. These findings provide empirical evidence that dispute resolution can be an effective, alternative means of mitigating supplier quality risks in online service procurement markets in place of ex-ante signals of provider quality. However, this is particularly true in settings where the output of work contracted can be objectively evaluated by a third-party.
Aminoglycoside 6'-N-acetyltransferase Type Ib [AAC(6')-Ib]-Mediated Aminoglycoside Resistance: Phenotypic Conversion to Susceptibility by Silver Ions.

Clinical resistance to amikacin and other aminoglycosides is usually due to the enzymatic acetylation of the antimicrobial molecule. A ubiquitous resistance enzyme among Gram-negatives is the aminoglycoside 6′-N-acetyltransferase type Ib [AAC(6′)-Ib], which catalyzes acetylation using acetyl-CoA as a donor substrate. Therapies that combine the antibiotic and an inhibitor of the inactivation reaction could be an alternative to treat infections caused by resistant bacteria. We previously observed that metal ions such as Zn2+ or Cu2+ in complex with ionophores interfere with the AAC(6′)-Ib-mediated inactivation of aminoglycosides and reduced resistance to susceptibility levels. Ag1+ recently attracted attention as a potentiator of aminoglycosides′ action by mechanisms still in discussion. We found that silver acetate is also a robust inhibitor of the enzymatic acetylation mediated by AAC(6′)-Ib in vitro. This action seems to be independent of other mechanisms, like increased production of reactive oxygen species and enhanced membrane permeability, proposed to explain the potentiation of the antibiotic effect by silver ions. The addition of this compound to aac(6′)-Ib harboring Acinetobacter baumannii and Escherichia coli cultures resulted in a dramatic reduction of the resistance levels. Time-kill assays showed that the combination of silver acetate and amikacin was bactericidal and exhibited low cytotoxicity to HEK293 cells.
Theory of reflectionless scattering modes

In this paper, the authors develop the theory of impedance matching of scattering waves to finite structures of arbitrary geometry, focusing on modes that have zero reflection back into the input channels at specific frequencies. The framework is applicable to all linear classical wave scattering, and to quantum scattering as long as the scattering potential is short ranged.
Universal Constants from Self-similarity and Adiabatic Invariance

We explore the idea that three universal constants of theoretical physics ( h , c , k B ) reflect the asymptotic approach to self-similarity and adiabatic invariance of weakly coupled oscillators.
Obstacles to the reuse of study metadata in ClinicalTrials.gov

Metadata that are structured using principled schemas and that use terms from ontologies are essential to making biomedical data findable and reusable for downstream analyses. The largest source of metadata that describes the experimental protocol, funding, and scientific leadership of clinical studies is ClinicalTrials.gov. We evaluated whether values in 302,091 trial records adhere to expected data types and use terms from biomedical ontologies, whether records contain fields required by government regulations, and whether structured elements could replace free-text elements. Contact information, outcome measures, and study design are frequently missing or underspecified. Important fields for search, such as condition and intervention, are not restricted to ontologies, and almost half of the conditions are not denoted by MeSH terms, as recommended. Eligibility criteria are stored as semi-structured free text. Enforcing the presence of all required elements, requiring values for certain fields to be drawn from ontologies, and creating a structured eligibility criteria element would improve the reusability of data from ClinicalTrials.gov in systematic reviews, metanalyses, and matching of eligible patients to trials.
Distributed cooperative decision making in multi-agent multi-armed bandits

Abstract We study a distributed decision-making problem in which multiple agents face the same multi-armed bandit (MAB), and each agent makes sequential choices among arms to maximize its own individual reward. The agents cooperate by sharing their estimates over a fixed communication graph. We consider an unconstrained reward model in which two or more agents can choose the same arm and collect independent rewards. And we consider a constrained reward model in which agents that choose the same arm at the same time receive no reward. We design a dynamic, consensus-based, distributed estimation algorithm for cooperative estimation of mean rewards at each arm. We leverage the estimates from this algorithm to develop two distributed algorithms: coop-UCB2 and coop-UCB2-selective-learning, for the unconstrained and constrained reward models, respectively. We show that both algorithms achieve group performance close to the performance of a centralized fusion center. Further, we investigate the influence of the communication graph structure on performance. We propose a novel graph explore–exploit index that predicts the relative performance of groups in terms of the communication graph, and we propose a novel nodal explore–exploit centrality index that predicts the relative performance of agents in terms of the agent locations in the communication graph.
Co-simulation Platform for Developing InfoRich Energy-Efficient Connected and Automated Vehicles

With advances in sensing, computing and communication technologies, Connected and Automated Vehicles (CAVs) are becoming feasible. The advent of CAVs presents new opportunities to improve the energy efficiency of individual vehicles. However, testing and verifying energy-efficient autonomous driving systems are difficult due to safety considerations and repeatability. In this paper, we present a co-simulation platform to develop and test novel vehicle eco-autonomous driving technologies named InfoRich, which incorporates the information from on-board sensors, V2X communications, and map database. The co-simulation platform includes eco-autonomous driving software, vehicle dynamics and powertrain (VD&PT) model, and a traffic environment simulator. Also, we utilize synthetic drive cycles derived from real-world driving data to test the strategies under realistic driving scenarios. To build road networks from the real-world driving data, we develop an Automated Parser and Calculator for Map/Scenario named AutoPASCAL. Overall, the simulation platform provides a realistic vehicle model, powertrain model, sensor model, traffic model, and road-network model to enable the evaluation of the energy efficiency of eco-autonomous driving.
Sub)Urban Poverty and Regional Interest Convergence

Poverty has expanded from America’s urban cores to its inner and outer suburban rings. In the midst of spreading hardship, new opportunities for confronting questions of regional equity are emerging, such as how best to govern our regional spaces for the benefit of all regional constituents, including the poor, middle class, and affluent. To date, governance theories have proven inadequate to this task. In the parlance of the current regional governance discourse localists, regionalists, and new regionalists need a framework to make a reality of their seemingly disparate and inconsistent visions of local versus regional interests. Localists champion the autonomy of local governments as the appropriate form of regional management. Regionalists, on the other hand, advocate for mechanisms of regional governance to manage the maintenance and development of regional spaces. While new regionalists have advocated practical steps to eliminate the causes of regional inequities, encouraging more efficient fiscal and land use planning cooperation between local governments in a metropolitan region, new regionalism as a social movement is stalled largely because it has existed as a set of ideals without a framework for effectuating those ideals. This Article introduces a new strategy, regional interest convergence, as a new social justice framework to effectuate new regionalism and revive the movement. Regional interest convergence, a reconceptualization of the interest convergence theory first articulated by Professor Derrick Bell, provides a framework for beginning to address both urban and suburban poverty.
The effects of fair value reporting on corporate foreign exchange exposures

We analyze the effects of fair value reporting standards (FVR) SFAS 133 and IAS 39 on foreign exchange (FX) exposures of U.S. multinational firms. We observe reductions in FX exposures to developed market currencies that coincide with the implementation of FVR. Risk reductions mainly affect U.S. multinational firms and to a much lesser extent matched control groups of domestic firms. For firms with exposures to emerging market currencies, we observe no changes in positive FX exposures but substantial shifts in negative exposures resulting in a change of exposure direction. Additionally we report changes in FX exposure asymmetry affecting multinational and domestic firms. Observed results are robust to several alternative model specifications and are unlikely explained by the launch of the euro, changes in firm-level FX exposure determinants, the rise and decline of technology shocks, shifts in systematic risk factors, or the Asian Financial Crisis.
State Action Problems

The state action doctrine is a mess. Explanations for why federal courts sometimes treat the private actions of private parties as public actions subject to the Constitution, as the Supreme Court did in Shelley v. Kraemer, are either vastly over-inclusive or fail to explain our law and values. A better approach is to understand the state action doctrine in institutional terms. I introduce a two-step, institutionally focused state action theory that is a natural consequence of a broader public–private theory of legal systems. In the first step, a court identifies a ―state action problem,‖ meaning a privately made law that is poorly governed by the ordinary rules governing the making of contracts. If a court finds a state action problem, it proceeds to the second step and decides whether courts have superior capacity to remedy the problem than do other governmental institutions. This theory captures important intuitions about the public regulation of private lawmaking that other approaches either ignore or fail to ground theoretically. In addition, it helps to justify why racial discrimination is often a decisive fact in finding state action, explains why the doctrine is rarely invoked, and provides a firm, theoretical foundation for a doctrine otherwise adrift in search of guiding principles. INTRODUCTION 282 I. EXISTING DOCTRINE AND APPROACHES 287 II. THE INSTITUTIONAL THEORY OF STATE ACTION: AN ALTERNATIVE APPROACH 294 A. The Bedrock 294 B. The Outcropping 302 1. The Nature of the Public–Private Inquiry 303 2. The First Step: State Action Problems 305 a. Covenants 308 b. Common-Interest Communities 310  Associate Professor Law, University of Georgia School of Law. For their help, criticism, and encouragement, I wish to thank Dan Coenen, Harlan Cohen, Christopher Elmendorf, Matthew Hall, Ethan Leib, Joseph Miller, Lori Ringhand, Albert Yoon, , and the participants of the University of Georgia Law School‘s junior faculty retreat. I would also like to thank the organizers and participants at the 2012 meeting of the Association for Law, Property, and Society at Georgetown University Law Center, where this paper was first delivered. For their research assistance, I would like to thank Barclay Hendrix, Matthew Noller, and Fritz Vaughan. 1 Turner: State Action Problems Published by UF Law Scholarship Repository, 2013 282 FLORIDA LAW REVIEW [Vol. 65 3. The Second Step: Judicial Intervention 313 III. A COMPARISON OF THE THEORIES IN ACTION 315 A. Taxonomy 316 1. Doctrinal Factors 316 2. Power 317 3. Balancing 319 4. Formal Identification 322 5. Functional Theories 323 B. Institutional Theory in Action 324 1. Shelley 324 2. Marsh 329 3. Other Cases 333 4. Private Action Problems 336 CONCLUSION 338
Intellectual Property’s Lessons for Information Privacy

There is an inherent tension between an individual’s desire to safeguard her personal information and the expressive rights of businesses seeking to communicate that information to others. This tension has multiplied as consumers generate and businesses collect more and more personal data online, forcing efforts to strike an appropriate balance between privacy and commercial speech. No consensus on this balance has been reached. Some privacy scholars bemoan what they see as a slanted playing field in favor of those wishing to profit from the private details of other people’s lives. Others contend that the right in free expression must always trump the diffuse, emotional concerns at the heart of privacy interests. What is missing from the debate is a detailed examination of the ways in which other legal regimes resolve their own tensions with the First Amendment. Intellectual property law offers a particularly valuable example. Rather than adopting a one-size fits all approach, intellectual property law has advanced a variety of approaches to reconciling property rights in intellectual creations with free speech rights. This Article describes those various approaches and maps them on to the different, yet similar terrain of information privacy regulation. This comparison reveals that courts and legislators have a number of potential tools to resolve the privacy/free speech divide.
Trade, Multinational Production, and the Gains from Openness

This paper quantifies the gains from openness arising from trade and multinational production (MP). We present a model that captures key dimensions of the interaction between these two flows: trade and MP are competing ways to serve a foreign market, MP relies on imports of intermediate goods from the home country, and foreign affiliates of multinationals can export part of their output. The calibrated model implies that the gains from trade can be twice as high as the gains calculated in trade-only models, while the gains from MP are slightly lower than the gains computed in MP-only models.
An interest rate defense of a fixed exchange rate

Defending a government’s exchange-rate commitment with active interest rate policy is not an option in first-generation models of speculative attacks. In those models, the interest rate is the passive reflection of currency-depreciation expectations. In this paper, we show how to adapt the first-generation framework to allow for an interest rate defense. It is shown that increasing domestic currency interest rate before the attack makes domestic assets more attractive according to an asset substitution effect, but weakens the domestic currency by increasing the government’s fiscal liabilities. As a result, an interest rate defense can be successful only conditional on sound fiscal policy.
Does Net Buying Pressure Affect the Shape of Implied Volatility Functions

This paper examines the relation between net buying pressure and the shape of the implied volatility function (IVF) for index and individual stock options. We find that changes in implied volatility are directly related to net buying pressure from public order flow. We also find that changes in implied volatility of S&P 500 options are most strongly affected by buying pressure for index puts, while changes in implied volatility of stock options are dominated by call option demand. Simulated delta-neutral option-writing trading strategies generate abnormal returns that match the deviations of the IVFs above realized historical return volatilities.
Compensating Changes to the Property Tax Levy? An Empirical Test of the Residual Rule:

The residual view of the property tax assumes that local governments set their levies equal to the difference between budgeted expenditures and expected receipts from other revenues. This approach ...