cssi/SciSciGPT-SciSciNet huggingface dataset:
Fourier domain rotational anisotropy-second harmonic generation

We describe a novel scheme of detecting rotational anisotropy-second harmonic generation (RA-SHG) signals using a lock-in amplifier referenced to a fast scanning RASHG apparatus. The method directly measures the nth harmonics of the scanning frequency corresponding to SHG signal components of Cn symmetry that appear in a Fourier series expansion of a general RA-SHG signal. GaAs was used as a test sample allowing comparison of point-by-point averaging with the lock-in based method. When divided by the C∞ signal component, the lock-in detected data allowed for both self-referenced determination of ratios of Cn components of up to 1 part in 104 and significantly more sensitive measurement of the relative amount of different Cn components when compared with conventional methods.
Systematic and Stochastic Variations in Pulsar Dispersion Measures

We analyze deterministic and random temporal variations in the dispersion measure (DM) from the full three-dimensional velocities of pulsars with respect to the solar system, combined with electron-density variations over a wide range of length scales. Previous treatments have largely ignored pulsars’ changing distances while favoring interpretations involving changes in sky position from transverse motion. Linear trends in pulsar DMs observed over 5–10 year timescales may signify sizable DM gradients in the interstellar medium (ISM) sampled by the changing direction of the line of sight to the pulsar. We show that motions parallel to the line of sight can also account for linear trends, for the apparent excess of DM variance over that extrapolated from scintillation measurements, and for the apparent non-Kolmogorov scalings of DM structure functions inferred in some cases. Pulsar motions through atomic gas may produce bow-shock ionized gas that also contributes to DM variations. We discuss the possible causes of periodic or quasi-periodic changes in DM, including seasonal changes in the ionosphere, annual variations of the solar elongation angle, structure in the heliosphere and ISM boundary, and substructure in the ISM. We assess the solar cycle’s role on the amplitude of ionospheric and solar wind variations. Interstellarmore » refraction can produce cyclic timing variations from the error in transforming arrival times to the solar system barycenter. We apply our methods to DM time series and DM gradient measurements in the literature and assess their consistency with a Kolmogorov medium. Finally, we discuss the implications of DM modeling in precision pulsar timing experiments.« less
Holographic description of AdS cosmologies

To gain insight in the quantum nature of the big bang, we study the dual field theory description of asymptotically anti-de Sitter solutions of supergravity that have cosmological singularities. The dual theories do not appear to have a stable ground state. One regularization of the theory causes the cosmological singularities in the bulk to turn into giant black holes with scalar hair. We interpret these hairy black holes in the dual field theory and use them to compute a finite temperature effective potential. In our study of the field theory evolution, we find no evidence for a ``bounce from a big crunch to a big bang. Instead, it appears that the big bang is a rare fluctuation from a generic equilibrium quantum gravity state.
Frobenius–Seshadri constants and characterizations of projective space

We introduce higher-order variants of the Frobenius-Seshadri constant due to Mustaţa and Schwede, which are defined for ample line bundles in positive characteristic. These constants are used to show that Demailly's criterion for separation of higher-order jets by adjoint bundles also holds in positive characteristic. As an application, we give a characterization of projective space using Seshadri constants in positive characteristic, which was proved in characteristic zero by Bauer and Szemberg. We also discuss connections with other characterizations of projective space.
Schmidt analysis of pure-state entanglement

We examine the application of Schmidt mode analysis to pure-state entanglement. Several examples permitting exact analytic calculation of Schmidt eigenvalues and eigenfunctions are included, as well as evaluation of the associated degree of entanglement.
Chebyshev's bias for products of $k$ primes

For any k≥1, we study the distribution of the difference between the number of integers n≤x with ω(n)=k or Ω(n)=k in two different arithmetic progressions, where ω(n) is the number of distinct prime factors of n and Ω(n) is the number of prime factors of n counted with multiplicity. Under some reasonable assumptions, we show that, if k is odd, the integers with Ω(n)=k have preference for quadratic nonresidue classes; and if k is even, such integers have preference for quadratic residue classes. This result confirms a conjecture of Richard Hudson. However, the integers with ω(n)=k always have preference for quadratic residue classes. Moreover, as k increases, the biases become smaller and smaller for both of the two cases.
How neutral is the intergalactic medium at z ∼ 6?

Recent observations of high-redshift quasar spectra reveal long gaps with little flux. A small or no detectable flux does not by itself imply that the intergalactic medium (IGM) is neutral. Inferring the average neutral fraction from the observed absorption requires assumptions about clustering of the IGM, which the gravitational instability model supplies. Our most stringent constraint on the neutral fraction at z ~ 6 is derived from the mean Lyβ transmission measured from the z = 6.28 Sloan Digital Sky Survey quasar of Becker and coworkers; the neutral hydrogen fraction at mean density has to be larger than 4.7 × 10-4. This is substantially higher than the neutral fraction of ~(3-5) × 10-5 at z = 4.5-5.7, suggesting that dramatic changes take place around or just before z ~ 6, even though current constraints are still consistent with a fairly ionized IGM at z ~ 6. These constraints also translate into constraints on the ionizing background, subject to uncertainties in the IGM temperature. An interesting alternative method to constrain the neutral fraction is to consider the probability of having many consecutive pixels with little flux, which is small unless the neutral fraction is high. It turns out that this constraint is slightly weaker than the one obtained from the mean transmission. We show that while the derived neutral fraction at a given redshift is sensitive to the power-spectrum normalization, the size of the jump around z ~ 6 is not. We caution that the main systematic uncertainties include spatial fluctuations in the ionizing background and the continuum placement. Tests are proposed. In particular, the sight line-to-sight line dispersion in mean transmission might provide a useful diagnostic. We express the dispersion in terms of the transmission power spectrum and develop a method to calculate the dispersion for spectra that are longer than the typical simulation box.
On the hyperbolic structure of moduli spaces with 16 SUSYs

We study the asymptotic limits of the heterotic string theories compactified on tori. We find a bilinear form uniquely determined by dualities which becomes Lorentzian in the case of one spacetime dimension. For the case of the SO(32) theory, the limiting descriptions include SO(32) heterotic strings, type I, type IA and other T-duals, M-theory on K3, type IIA theory on K3 and type IIB theory on K3 and possibly new limits not understood yet.
Homogeneous Ricci solitons are algebraic

In this short note, we show that homogeneous Ricci solitons are algebraic. As an application, we see that the generalized Alekseevskii conjecture is equivalent to the Alekseevskii conjecture.
Neuroreceptor Activation by Vibration-Assisted Tunneling

G protein-coupled receptors (GPCRs) constitute a large family of receptor proteins that sense molecular signals on the exterior of a cell and activate signal transduction pathways within the cell. Modeling how an agonist activates such a receptor is fundamental for an understanding of a wide variety of physiological processes and it is of tremendous value for pharmacology and drug design. Inelastic electron tunneling spectroscopy (IETS) has been proposed as a model for the mechanism by which olfactory GPCRs are activated by a bound agonist. We apply this hyothesis to GPCRs within the mammalian nervous system using quantum chemical modeling. We found that non-endogenous agonists of the serotonin receptor share a particular IET spectral aspect both amongst each other and with the serotonin molecule: a peak whose intensity scales with the known agonist potencies. We propose an experiential validation of this model by utilizing lysergic acid dimethylamide (DAM-57), an ergot derivative, and its deuterated isotopologues; we also provide theoretical predictions for comparison to experiment. If validated our theory may provide new avenues for guided drug design and elevate methods of in silico potency/activity prediction.
Men Set Their Own Cites High: Gender and Self-citation across Fields and over Time:

How common is self-citation in scholarly publication, and does the practice vary by gender? Using novel methods and a data set of 1.5 million research papers in the scholarly database JSTOR published between 1779 and 2011, the authors find that nearly 10 percent of references are self-citations by a paper’s authors. The findings also show that between 1779 and 2011, men cited their own papers 56 percent more than did women. In the last two decades of data, men self-cited 70 percent more than women. Women are also more than 10 percentage points more likely than men to not cite their own previous work at all. While these patterns could result from differences in the number of papers that men and women authors have published rather than gender-specific patterns of self-citation behavior, this gender gap in self-citation rates has remained stable over the last 50 years, despite increased representation of women in academia. The authors break down self-citation patterns by academic field and number of authors ...
The inversion formula and 6j symbol for 3d fermions

In this work we study the 6j symbol of the 3d conformal group for fermionic operators. In particular, we study 4-point functions containing two fermions and two scalars and also those with four fermions. By using weight-shifting operators and harmonic analysis for the Euclidean conformal group, we relate these spinning 6j symbols to the simpler 6j symbol for four scalar operators. As one application we use these techniques to compute 3d mean field theory (MFT) OPE coefficients for fermionic operators. We then compute corrections to the MFT spectrum and couplings due to the inversion of a single operator, such as the stress tensor or a low-dimension scalar. These results are valid at finite spin and extend the perturbative large spin analysis to include non-perturbative effects in spin.
Multiuser Scheduling in a Markov-Modeled Downlink Using Randomly Delayed ARQ Feedback

This paper focuses on the downlink of a cellular system and studies opportunistic multiuser scheduling under imperfect channel state information, by exploiting the memory inherent in the channel. The channel between the base station and each user is modeled by a two-state Markov chain and the scheduled user sends back an ARQ feedback that arrives at the scheduler with a random delay, i.i.d. across users and time. The scheduler indirectly estimates the channel via accumulated delayed-ARQ feedback and uses this information to make scheduling decisions. The throughput maximization problem is formulated as a partially observable Markov decision process (POMDP). For the case of two users in the system, it is shown that a greedy policy is sum throughput optimal for any distribution on the ARQ feedback delay. For the case of more than two users, the greedy policy is suboptimal and numerical studies demonstrate that it has near optimal performance. Also, the greedy policy can be implemented by a simple algorithm that does not require the statistics of the underlying Markov channel or the ARQ feedback delay, thus making it robust against errors in system parameter estimation. Establishing an equivalence between the two-user system and a genie-aided system, a simple closed form expression for the sum capacity of the downlink is obtained. Further, inner and outer bounds on the capacity region of the downlink are obtained.
Density nonlinearities and a field theory for the dynamics of simple fluids

We study the role of the Jacobian arising from a constraint enforcing the nonlinear relationg=ρV, where ρ,g, andV are the mass density, the momentum density, and the local velocity field, respectively, in the field-theoretic formulation of the nonlinear fluctuating hydrodynamics of simple fluids. By investigating the Jacobian directly and by developing a field-theoretic formulation without the constraint, we find that no changes in dynamics result as compared to the previous formulation developed by Das and Mazenko (DM). In particular, the cutoff mechanism discovered by DM is shown to be a consequence of the 1/ρ nonlinearity in the problem, not of the constraint. The consequences of this result for the static properties of the system are also discussed.
High Energy Variability Of Synchrotron‐Self Compton Emitting Sources: Why One Zone Models Do Not Work And How We Can Fix It

With the anticipated launch of GLAST, the existing X‐ray telescopes, and the enhanced capabilities of the new generation of TeV telescopes, developing tools for modeling the variability of high energy sources such as blazars is becoming a high priority. We point out the serious, innate problems one zone synchrotron‐self Compton models have in simulating high energy variability. We then present the first steps toward a multi zone model where non‐local, time delayed Synchrotron‐self Compton electron energy losses are taken into account. By introducing only one additional parameter, the length of the system, our code can simulate variability properly at Compton dominated stages, a situation typical of flaring systems. As a first application, we were able to reproduce variability similar to that observed in the case of the puzzling ‘orphan’ TeV flares that are not accompanied by a corresponding X‐ray flare.
The Baker–Akhiezer Function and Factorization of the Chebotarev–Khrapkov Matrix

A new technique is proposed for the solution of the Riemann–Hilbert problem with the Chebotarev–Khrapkov matrix coefficient $${G(t) = \alpha_{1}(t)I + \alpha_{2}(t)Q(t)}$$ , $${\alpha_{1}(t), \alpha_{2}(t) \in H(L)}$$ , I = diag{1, 1}, Q(t) is a $${2\times2}$$ zero-trace polynomial matrix. This problem has numerous applications in elasticity and diffraction theory. The main feature of the method is the removal of essential singularities of the solution to the associated homogeneous scalar Riemann–Hilbert problem on the hyperelliptic surface of an algebraic function by means of the Baker–Akhiezer function. The consequent application of this function for the derivation of the general solution to the vector Riemann–Hilbert problem requires the finding of the $${\rho}$$ zeros of the Baker–Akhiezer function ( $${\rho}$$ is the genus of the surface). These zeros are recovered through the solution to the associated Jacobi problem of inversion of abelian integrals or, equivalently, the determination of the zeros of the associated degree- $${\rho}$$ polynomial and solution of a certain linear algebraic system of $${\rho}$$ equations.
EXPLORING SYSTEMATIC EFFECTS IN THE RELATION BETWEEN STELLAR MASS, GAS PHASE METALLICITY, AND STAR FORMATION RATE

There is evidence that the well-established mass-metallicity relation in galaxies is correlated with a third parameter: star formation rate (SFR). The strength of this correlation may be used to disentangle the relative importance of different physical processes (e.g., infall of pristine gas, metal-enriched outflows) in governing chemical evolution. However, all three parameters are susceptible to biases that might affect the observed strength of the relation between them. We analyze possible sources of systematic error, including sample bias, application of signal-to-noise ratio cuts on emission lines, choice of metallicity calibration, uncertainty in stellar mass determination, aperture effects, and dust. We present the first analysis of the relation between stellar mass, gas phase metallicity, and SFR using strong line abundance diagnostics from Dopita et al. (2013) for ~130,000 star-forming galaxies in the Sloan Digital Sky Survey and provide a detailed comparison of these diagnostics in an appendix. Using these abundance diagnostics yields a 30-55% weaker anti-correlation between metallicity and SFR at fixed stellar mass than that reported by Mannucci et al. (2010). We find that, for all abundance diagnostics, the anti-correlation with SFR is stronger for the relatively few galaxies whose current SFRs are elevated above their past average SFRs. This is also true for the new abundance diagnostic of Dopita et al. (2016), which gives anti-correlation between metallicity and SFR only in the high specific star formation rate (sSFR) regime, in contrast to the recent results of Kashino et al. (2016). The poorly constrained strength of the relation between stellar mass, metallicity, and SFR must be carefully accounted for in theoretical studies of chemical evolution.
Level Spacing for Non-Monotone Anderson Models

We prove localization and probabilistic bounds on the minimum level spacing for a random block Anderson model without monotonicity. Using a sequence of narrowing energy windows and associated Schur complements, we obtain detailed probabilistic information about the microscopic structure of energy levels of the Hamiltonian, as well as the support and decay of eigenfunctions.
Generalized Kuga–Satake theory and good reduction properties of Galois representations

In previous work we described when a single geometric representation, valued in a linear algebraic group, of the Galois group of a number field lifts through a central torus quotient to a geometric representation. In this paper we prove a much sharper result for systems of l-adic representations, such as the l-adic realizations of a motive, having common "good reduction" properties. Namely, such systems admit geometric lifts with good reduction outside a common finite set of primes. The method yields new proofs of theorems of Tate (the original result on lifting projective representations over number fields) and Wintenberger (an analogue of our main result in the setting of lifting through a central isogeny).
Relativistic viscous fluid dynamics and non-equilibrium entropy

Fluid dynamics corresponds to the dynamics of a substance in the long wavelength limit. Writing down all terms in a gradient (long wavelength) expansion up to second order for a relativistic system at vanishing charge density, one obtains the most general (causal) equations of motion for a fluid in the presence of shear and bulk viscosity, as well as the structure of the non-equilibrium entropy current. Requiring positivity of the divergence of the non-equilibrium entropy current relates some of its coefficients to those entering the equations of motion. I comment on possible applications of these results for conformal and non-conformal fluids.
Consistency between 11D and U-duality

U duality transformations must act on a basis of states that form complete multiplets of the U group, at any coupling, even though the states may not be mass degenerate, as for a broken symmetry. Similarly, if superstring theory is related to a non-perturbative 11D M-theory, then an 11D supermultiplet structure is expected, even though the multiplet may contain states of different masses. We analyse the consistency between these two multiplet schemes at the higher excited string levels for various compactifications of the type IIA superstring. While we find complete consistency for a number of compactifications, there remain some unanswered questions in others. The relation to D-branes also needs further clarification.
Quantum cosmology: a review

In quantum cosmology, one applies quantum physics to the whole universe. While no unique version and no completely well-defined theory is available yet, the framework gives rise to interesting conceptual, mathematical and physical questions. This review presents quantum cosmology in a new picture that tries to incorporate the importance of inhomogeneity. De-emphasizing the traditional minisuperspace view, the dynamics is rather formulated in terms of the interplay of many interacting 'microscopic' degrees of freedom that describe the space-time geometry. There is thus a close relationship with more-established systems in condensed-matter and particle physics even while the large set of space-time symmetries (general covariance) requires some adaptations and new developments. These extensions of standard methods are needed both at the fundamental level and at the stage of evaluating the theory by effective descriptions.
Marginal likelihood for parallel series

Suppose that $k$ series, all having the same autocorrelation function, are observed in parallel at $n$ points in time or space. From a single series of moderate length, the autocorrelation parameter $β$ can be estimated with limited accuracy, so we aim to increase the information by formulating a suitable model for the joint distribution of all series. Three Gaussian models of increasing complexity are considered, two of which assume that the series are independent. This paper studies the rate at which the information for $β$ accumulates as $k$ increases, possibly even beyond $n$. The profile log likelihood for the model with $k(k+1)/2$ covariance parameters behaves anomalously in two respects. On the one hand, it is a log likelihood, so the derivatives satisfy the Bartlett identities. On the other hand, the Fisher information for $β$ increases to a maximum at $k=n/2$, decreasing to zero for $k≥n$. In any parametric statistical model, one expects the Fisher information to increase with additional data; decreasing Fisher information is an anomaly demanding an explanation.
Learning Affordance Landscapes for Interaction Exploration in 3D Environments

Embodied agents operating in human spaces must be able to master how their environment works: what objects can the agent use, and how can it use them? We introduce a reinforcement learning approach for exploration for interaction, whereby an embodied agent autonomously discovers the affordance landscape of a new unmapped 3D environment (such as an unfamiliar kitchen). Given an egocentric RGB-D camera and a high-level action space, the agent is rewarded for maximizing successful interactions while simultaneously training an image-based affordance segmentation model. The former yields a policy for acting efficiently in new environments to prepare for downstream interaction tasks, while the latter yields a convolutional neural network that maps image regions to the likelihood they permit each action, densifying the rewards for exploration. We demonstrate our idea with AI2-iTHOR. The results show agents can learn how to use new home environments intelligently and that it prepares them to rapidly address various downstream tasks like "find a knife and put it in the drawer." Project page: this http URL
Lyman Break Galaxies and the Reionization of the Intergalactic Medium

Near-infrared observations of Lyman break galaxies at redshifts of z ~ 3 are beginning to provide constraints on ages, star formation histories, dust content, metallicities, and stellar masses. At present, uncertainties of more than an order of magnitude are typical for many of these parameters. It is nonetheless interesting to ask what the stellar population models imply for the existence and luminosities of Lyman break galaxies at higher redshift. To this end we examine the inferred star formation rates in two well-studied samples of galaxies as a function of redshift out to z = 10 for various best-fitting and limiting cases. Taken at face value, the generally young ages (typically 108±0.5 yr) of the z = 3 Lyman break galaxies imply that their stars were not present much beyond z = 4. By z = 6 the cosmic star formation rate SFR from the progenitors of these galaxies is less than 10% of SFR at z = 3 ± 0.5, even for maximally old models, provided the derivative of the star formation rate SFR(t) is monotonic. The escaping Lyman continuum radiation from such galaxies would be insufficient to reionize the intergalactic medium. Thus, other sources of ionizing photons (e.g., very massive Population III stars) may be needed, and the more normal Lyman break galaxies may be a phenomenon confined to redshifts of z 4. This conclusion changes if SFR(t) was episodic, and we examine the parameters of such bursty star formation that might be consistent with both the z = 2-4 luminosity functions and the z ~ 3 spectral energy distributions.
A CATALOG OF GALEX ULTRAVIOLET EMISSION FROM SPECTROSCOPICALLY CONFIRMED M DWARFS

We present a catalog of GALEX Near-UV (NUV) and Far-UV (FUV) photometry for the Palomar/MSU and SDSS DR7 spectroscopic M dwarf catalogs. The catalog contains NUV measurements matched to 577 spectroscopically confirmed M dwarfs and FUV measurements matched to 150 spectroscopically confirmed M dwarfs. Using these data, we find that NUV and FUV luminosities strongly correlate with H{\alpha} emission, a typical indicator of magnetic activity in M dwarfs. We also examine the fraction of M dwarfs with varying degrees of strong line emission at NUV wavelengths. Our results indicate that the frequency of M dwarf NUV emission peaks at intermediate spectral types, with at least ~30% of young M4-M5 dwarfs having some level of activity. For mid-type M dwarfs, we show that NUV emission decreases with distance from the Galactic plane, a proxy for stellar age. Our complete matched source catalog is available online.
Matrix Models and Large-N Behavior

Following the procedures by which O(N)-invariant real vector models and their large-N behavior have previously been solved, we extend similar techniques to the study of real symmetric N×N-matrix models with O(N)-invariant interactions. Proper extensions to N = ∞ are also established. While no 1/N-expansions are involved in our analysis, a brief comparison of our procedures with traditional 1/N-expansion procedures is given.
On the Semimajor Axis Distribution of Extrasolar Gas Giant Planets: Why Hot Jupiters are Rare Around High-Mass Stars

Based on a suite of Monte Carlo simulations, I show that a stellar-mass-dependent lifetime of the gas disks from which planets form can explain the lack of hot Jupiters/close-in giant planets around high-mass stars and other key features of the observed semimajor axis distribution of radial velocity-detected giant planets. Using reasonable parameters for the Type II migration rate, regions of planet formation, and timescales for gas giant core formation, I construct synthetic distributions of Jovian planets. A planet formation/migration model assuming a stellar-mass-dependent gas disk lifetime reproduces key features in the observed distribution by preferentially stranding planets around high-mass stars at large semimajor axes.
Improved adaptive group testing algorithms with applications to multiple access channels and dead sensor diagnosis

We study group-testing algorithms for resolving broadcast conflicts on a multiple access channel (MAC) and for identifying the dead sensors in a mobile ad hoc wireless network. In group-testing algorithms, we are asked to identify all the defective items in a set of items when we can test arbitrary subsets of items. In the standard group-testing problem, the result of a test is binary—the tested subset either contains defective items or not. In the more generalized versions we study in this paper, the result of each test is non-binary. For example, it may indicate whether the number of defective items contained in the tested subset is zero, one, or at least two.
The chiral anomaly, Dirac and Weyl semimetals, and force-free magnetic fields

The chiral anomaly is a purely quantum mechanical phenomenon that has a long history dating back to the late 1960s. Surprisingly, it has recently made a macroscopic appearance in condensed matter physics. A brief introduction to the relevant features of this anomaly is given and it is shown that its appearance in condensed matter systems must involve force-free magnetic fields, which may help explain the long current relaxation times in Dirac and Weyl semimetals.
K-band calibration of the red clump luminosity

The average near-infrared (K-band) luminosity of 238 Hipparcos red clump giants is derived and then used to measure the distance to the Galactic center. These Hipparcos red clump giants have been previously employed as I-band standard candles. The advantage of the K-band is a decreased sensitivity to reddening and perhaps a reduced systematic dependence on metallicity. In order to investigate the latter, and also to refer our calibration to a known metallicity zero point, we restrict our sample of red clump calibrators to those with abundances derived from high-resolution spectroscopic data. The mean metallicity of the sample is [Fe/H] = -0.18 dex (σ = 0.17 dex). The data are consistent with no correlation between MK and [Fe/H] and only weakly constrain the slope of this relation. The luminosity function of the sample peaks at MK = -1.61 ± 0.03 mag. Next, we assemble published optical and near-infrared photometry for ~20 red clump giants in a Baade's window field with a mean metallicity of [Fe/H] = -0.17 ± 0.09 dex, which is nearly identical to that of the Hipparcos red clump. Assuming that the average (V-I)0 and (V-K)0 colors of these two red clumps are the same, the extinctions in the Baade's window field are found to be AV = 1.56, AI = 0.87, and AK = 0.15, in agreement with previous estimates. We derive the distance to the Galactic center: (m - M)0 = 14.58 ± 0.11 mag, or R = 8.24 ± 0.42 kpc. The uncertainty in this distance measurement is dominated by the small number of Baade's window red clump giants examined here.
Counting in Graph Covers: A Combinatorial Characterization of the Bethe Entropy Function

We present a combinatorial characterization of the Bethe entropy function of a factor graph, such a characterization being in contrast to the original, analytical, definition of this function. We achieve this combinatorial characterization by counting valid configurations in finite graph covers of the factor graph. Analogously, we give a combinatorial characterization of the Bethe partition function, whose original definition was also of an analytical nature. As we point out, our approach has similarities to the replica method, but also stark differences. The above findings are a natural backdrop for introducing a decoder for graph-based codes that we will call symbolwise graph-cover decoding, a decoder that extends our earlier work on blockwise graph-cover decoding. Both graph-cover decoders are theoretical tools that help toward a better understanding of message-passing iterative decoding, namely blockwise graph-cover decoding links max-product (min-sum) algorithm decoding with linear programming decoding, and symbolwise graph-cover decoding links sum-product algorithm decoding with Bethe free energy function minimization at temperature one. In contrast to the Gibbs entropy function, which is a concave function, the Bethe entropy function is in general not concave everywhere. In particular, we show that every code picked from an ensemble of regular low-density parity-check codes with minimum Hamming distance growing (with high probability) linearly with the block length has a Bethe entropy function that is convex in certain regions of its domain.
Domain2Vec: Domain Embedding for Unsupervised Domain Adaptation

Conventional unsupervised domain adaptation (UDA) studies the knowledge transfer between a limited number of domains. This neglects the more practical scenario where data are distributed in numerous different domains in the real world. A technique to measure domain similarity is critical for domain adaptation performance. To describe and learn relations between different domains, we propose a novel Domain2Vec model to provide vectorial representations of visual domains based on joint learning of feature disentanglement and Gram matrix. To evaluate the effectiveness of our Domain2Vec model, we create two large-scale cross-domain benchmarks. The first one is TinyDA, which contains 54 domains and about one million MNIST-style images. The second benchmark is DomainBank, which is collected from 56 existing vision datasets. We demonstrate that our embedding is capable of predicting domain similarities that match our intuition about visual relations between different domains. Extensive experiments are conducted to demonstrate the power of our new datasets in benchmarking state-of-the-art multi-source domain adaptation methods, as well as the advantage of our proposed model (Data and code are available at https://github.com/VisionLearningGroup/Domain2Vec).
Open Set Wireless Transmitter Authorization: Deep Learning Approaches and Dataset Considerations

Due to imperfections in transmitters’ hardware, wireless signals can be used to verify their identity in an authorization system. While deep learning was proposed for transmitter identification, existing work has mainly focused on classification among a closed set of transmitters. Malicious transmitters outside this closed set will be misclassified, jeopardizing the authorization system. In this article, we formulate the problem of recognizing authorized transmitters and rejecting new transmitters as open set recognition and anomaly detection. We consider approaches based on one and several binary classifiers, multiclass classifiers, and signal reconstruction. We study how these approaches scale with the required number of authorized transmitters. We propose using a known set of unauthorized transmitters to assist the training and study its impact. The evaluation procedure takes into consideration that some transmitters might be more similar than others and nuances these effects. The authorization’s robustness against temporal changes in fingerprints is also evaluated as a function of the approach and the dataset structure. When using 10 authorized and 50 known unauthorized WiFi transmitters from a publicly accessible testbed, we were able to achieve an outlier detection accuracy of 98% on the same day test set and 80% on the different day test set.
From a systematic investigation of faculty-produced Think-Pair-Share questions to frameworks for characterizing and developing fluency-inspiring activities

Demonstration of how the analysis of faculty-produced questions is generative for developing frameworks for the characterization of curriculum and the development of curriculum in astronomy.
Nonlinear diffusion in the Keller-Segel model of parabolic-parabolic type

Abstract In this paper we study the initial boundary value problem for the system u t − Δ u m = − div ( u q ∇ v ) , v t − Δ v + v = u . This problem is the so-called Keller-Segel model with nonlinear diffusion. Our investigation reveals that nonlinear diffusion can prevent overcrowding. To be precise, we show that solutions are bounded as long as m > q > 0 , thereby substantially generalizing the known results in this area. Furthermore, our result seems to imply that the Keller-Segel model can have bounded solutions and blow-up ones simultaneously.
Is a handful of genes responsible for the common starling invasion success

Invasive species have the ability to colonize new habitats across distinct areas of the globe, rapidly adjusting to new biotic and abiotic conditions, and often experiencing little impact from the decrease in effective population size and genetic diversity. Still, as each invading population represents a subsample of the original native distribution, it is common to see variability in terms of the genetic makeup of invading populations and consequently differences in invasion success rates across their non-native range (Blackburn et al., 2017). In a From the Cover article in this issue of Molecular Ecology, Stuart et al. (2020) used genotyping-by-sequencing to explore how landscape and environmental heterogeneity shaped the genetic population structure and adaptation of multiple invasions of the common starling in Australia, and compared it to the patterns observed in North America, examined in Hofmeister et al. (2019). Their results suggest that the common starling worldwide invasion has been driven by a handful of genes that allowed adaptation to extreme environmental conditions and might be the key for differences in invasion success.
GAAP as a symbol of legitimacy: New York State's decision to adopt generally accepted accounting principles

Abstract In this paper, we draw on economic and sociological theories in order to explain public sector incentives to adopt generally accepted accounting principles (GAAP), using the state of New York's decision to adopt GAAP for external financial reporting. We argue that the state's decision to adopt GAAP was an attempt to regain legitimacy for the state's financial management practices. Institutional interests demanding New York use GAAP were part of the sociological phenomenon called institutional isomorphism. Power relations and organizational politics related to the state's budgetary process also significantly influenced the state's decision to adopt GAAP. However, although professional elites made strong statements that GAAP adoption would improve the state's financial management practices, we found no compelling evidence that producing GAAP financial information has significantly altered the state's financial management practices.
The Termination of Subprime Hybrid and Fixed-Rate Mortgages

Adjustable-rate and hybrid loans have been a larger component of subprime mortgage lending in the mortgage market than prime lending. The typical adjustable-rate loan in subprime is a hybrid of fixed and adjustable characteristics in which the first 2 years are fixed and the remaining 28 years adjustable. Hybrid loans terminate at elevated probabilities even before the first adjustment date. Hybrid loan terminations are sensitive to interest rates and teaser rates (payment shocks). Default probabilities increase dramatically when payment shocks are mixed with low or no equity in the home. This is the mixture of events that helped to trigger the 2007/2008 subprime mortgage crisis.
Is Market Timing Good for Shareholders

We challenge the view that equity market timing always benets shareholders. By distinguishing the eect of a rm’s equity decisions from the eect of mispricing itself, we show that market timing can decrease shareholder value. Additionally, the timing of equity sales has a more negative eect on existing shareholders than the timing of share repurchases. Our theory can be used to infer rms’ maximization objectives from their observed market timing strategies. We argue that the popularity of stock buybacks and the low frequency of seasoned equity oerings
The effects of rejecting aid on recipients’ reputations: Evidence from natural disaster responses

How do states improve their international status and prestige short of war? We argue that rejecting international assistance can boost a government’s image by making it appear self-sufficient and able to provide for its citizens, leading many states to decline foreign aid. However, potential recipients only do so when they have the ability to send a credible signal and when they value status highly. We derive these hypotheses from a formal model and then use a survey experiment to demonstrate that international observers alter their opinions about potential recipients when they learn that they rejected international aid. Finally, we gather new data to empirically verify that the more resources and greater military capabilities states possess, the more likely they are to reject aid, even when they require the aid. Our results help to explain why states refuse needed assistance and suggest that many states cultivate images of self-sufficiency.
Can online piracy be stopped by laws

Considering the legal responsibilities of Internet intermediaries in the aftermath of the Stop Online Privacy Act controversy.
Back to the Future with Chapter 13: A Response to Professor Scarberry

Professor Mark Scarberry has put forth a formidable critique of my empirical study of mortgage market sensitivity to bankruptcy modification risk. As this response shows, however, his critique does not hold up under scrutiny. Professor Scarberry argues that my study design is invalid because, as he reads the current state of the law, cramdown is virtually impossible. Therefore, he contends, we should not expect markets to exhibit sensitivity to cramdown risk, so no policy conclusions can be derived from my finding of market insensitivity. Regrettably, Professor Scarberry overreads the state of the law. The law is in fact unsettled, and that is all that is necessary to uphold the validity of my study’s design because the market can be expected to price for uncertainty about the law, and the absence of such a premium is significant. This response article also challenges Professor Scarberry’s contention that Chapter 13 relief should be limited lest it engender “resentment” of debtors. The article questions whether prevention of resentment even provides a sound basis for limiting bankruptcy relief, much less when relief would further an important macroeconomic goal of housing market stabilization. More broadly, the article takes issues with claims about the sanctity of secured credit. Debates about the efficiency of secured credit have all played out in the business context. In the consumer context, however, the inefficiency is manifest. Treating secured credit as inviolable would take us back to the unhappy future of Chapter XIII with higher costs for unsecured credit and the abusive consumer finance world of Williams v. Walker-Thomas.
Corporate Ethics in a Devilish System

Prepared for a roundtable on corporate ethics at the University of Maryland School of Law, this essay argues that discussions of corporate ethics that focus on mere compliance with law are too narrow. While an emphasis on legal compliance is indeed crucial, a dedication to legality standing alone is hardly a robust sense of ethics, corporate or otherwise. Whether one takes guidance from religious norms or from secular philosophers, there are significant areas of agreement as to what amounts to ethical behavior: acting with due care for others; taking responsibility for the effect of one's actions; being honest; considering broadly one's impacts; and taking a long-term view, especially with regard to resource use.Corporate law and financial markets operate to make these ethical obligations difficult to satisfy in a business setting. Limited liability, for example, is inconsistent with the ethical norm of taking responsibility for one's own actions since it shields people from liability that arises from their wrongful conduct. This essay argues that we should adjust the law to make ethical norms real and impactful. If the corporations, as institutions, are indeed without consciences - the prototypical Holmesian "Bad Man" - and corporate managers are limited by their role morality, then the way to make corporate ethics more than a public relations gimmick is to embody them in law.
PHYSICIANS' LEGAL DUTIES REGARDING THE USE OF GENETIC TESTS TO PREDICT AND DIAGNOSE ALZHEIMER DISEASE

This article identifies and explores the possible impact of genetic science advances concerning Alzheimer's disease on legal standards delineating acceptable medical practice in the realm of predicting and diagnosing Alzheimer's disease, and on the potential liability exposure of physicians who care for patients who are now, or in the future may become, Alzheimer's disease victims. Specific issues addressed include: What obligation, if any, does a physician owe a patient to offer genotyping for Alzheimer's disease for predictive purposes? For diagnostic purposes? What are the informed consent ramifications of such offers? To what extent, if any, is there a duty on the physician's part to perform genetic testing for Alzheimer's disease in response to patient demand? What standards of care apply to the physician's communication of Alzheimer's-related genetic testing results to a patient? What confidentiality considerations apply to Alzheimer's disease-related genetic information about a patient, particularly if potential rights of third parties must be taken into account?
Complementarity and Post-Coloniality

The International Criminal Court’s jurisdiction is complementary to that of national criminal jurisdictions. While most agree that complementarity is a cornerstone principle, debate continues as to what precisely it should mean for the ICC’s relationship to national criminal justice actors. “Positive complementarity,” a view many commentators hold, suggests that the ICC should use its power to educate, persuade, and prod states parties to undertake international criminal law investigations. For positive complementarity’s more optimistic proponents, the future holds promise for a coordinated system of global justice in which the ICC plays a secondary role to national courts in vindicating international criminal law violations. In this essay, based on remarks presented at the Emory International Law Review’s 2013 Symposium on the ICC’s future, I argue that a robust regime of positive complementarity will require that the ICC deftly navigate a post-colonial landscape—i.e., widespread underdevelopment, political and social fragmentation, and epistemic heterogeneity. Doing so effectively will require tools the ICC does not have and a willingness to make political judgments that may seem unbecoming of a court. These limitations raise more profound questions about whether the ICC can speak to those who inhabit the globe’s most desperately marginal spaces. While I am skeptical that it can, it is also unclear that domestic criminal justice actors are better equipped to do so. I conclude by suggesting that it may be more constructive to analyze complementarity through a descriptive lens rather than in grand normative terms. In this vein, I suggest that a “governmentality” framework that focuses on the development of bureaucratic culture may be useful for future research on complementarity. * Assistant Professor of Law, Georgia State University College of Law. Thanks to Jonathan Todres, Natsu Saito, and Deepa Varadarajan for comments. SEKHON GALLEYSPROOFS 4/14/2014 9:57 AM 800 EMORY INTERNATIONAL LAW REVIEW [Vol. 27 INTRODUCTION 800 I. BACKGROUND 801 II. POST-COLONIAL DILEMMAS 804 A. Justice Without Judges? 804 1. Rule of Law in the “Third World” 805 2. ICC and Capacity Building 808 B. Universal Law for Universal Misconduct 810 C. Politics, Sovereignty, and Justice 816 D. Speaking to the Subaltern 820 III. COMPLEMENTARITY AND GOVERNMENTALITY 825 CONCLUSION 828
The Role of Private Disclosures in Markets with Weak Institutions: Evidence from Market Liberalization in China

I use the announcement of a market liberalization pilot program in China as a shock to firms’ disclosure environment and examine how the Chinese firms, foreign investors, and foreign brokers respond. Using a proprietary dataset, I find that affected firms respond to announcement by significantly increasing the number of selective private meetings hosted by major foreign brokers, but do not use public disclosure channels. I find this increase in private disclosure to be stronger among firms that had strong public disclosure track record and are in need of capital. Firms that increased private disclosure experience improvements in speed of price discovery and liquidity. In addition, they also experience an increase in foreign holdings and raise capital abroad through foreign brokers after the pilot program’s implementation. Overall, this paper takes a yet-to-mature economy, presents evidence on dynamic shaping of disclosure, and highlights private disclosure as an important positive channel of communication.