cssi/SciSciGPT-SciSciNet huggingface dataset:
Solitons, boundary value problems and a nonlinear method of images

We characterize the soliton solutions of the nonlinear Schrodinger equation on the half-line with linearizable boundary conditions. Using an extension of the solution to the whole line and the corresponding symmetries of the scattering data, we identify the properties of the discrete spectrum of the scattering problem. We show that discrete eigenvalues appear in quartets as opposed to pairs in the initial value problem, and we obtain explicit relations for the norming constants associated with symmetric eigenvalues. The apparent reflection of each soliton at the boundary of the spatial domain is due to the presence of a 'mirror' soliton, with equal amplitude and opposite velocity, located beyond the boundary. We then calculate the position shift of the physical solitons as a result of the nonlinear reflection. These results provide a nonlinear analogue of the method of images that is used to solve boundary value problems in electrostatics.
Statistical Distributions of Pyrosequencing

Pyrosequencing is emerging as one of the important next-generation sequencing technologies. We derive the statistical distributions of this technique in terms of nucleotide probabilities of the target sequences. We give exact distributions both for fixed number of flow cycles and for fixed sequence length. Explicit formulas are derived for the mean and variance of these distributions. In both cases, the distributions can be approximated accurately by normal distributions with the same mean and variance. The statistical distributions will be useful for instrument and software development for pyrosequencing platforms.
Localization in the Disordered Holstein Model

The Holstein model describes the motion of a tight-binding tracer particle interacting with a field of quantum harmonic oscillators. We consider this model with an on-site random potential. Provided the hopping amplitude for the particle is small, we prove localization for matrix elements of the resolvent, in particle position and in the field Fock space. These bounds imply a form of dynamical localization for the particle position that leaves open the possibility of resonant tunneling in Fock space between equivalent field configurations.
Feynman—Schwinger duality

Brief recollections of two giants of physics, their origins, similarities, and differences.Brief recollections of two giants of physics, their origins, similarities, and differences.
Hierarchical Evidence Set Modeling for Automated Fact Extraction and Verification

Automated fact extraction and verification is a challenging task that involves finding relevant evidence sentences from a reliable corpus to verify the truthfulness of a claim. Existing models either (i) concatenate all the evidence sentences, leading to the inclusion of redundant and noisy information; or (ii) process each claim-evidence sentence pair separately and aggregate all of them later, missing the early combination of related sentences for more accurate claim verification. Unlike the prior works, in this paper, we propose Hierarchical Evidence Set Modeling (HESM), a framework to extract evidence sets (each of which may contain multiple evidence sentences), and verify a claim to be supported, refuted or not enough info, by encoding and attending the claim and evidence sets at different levels of hierarchy. Our experimental results show that HESM outperforms 7 state-of-the-art methods for fact extraction and claim verification. Our source code is available at https://github.com/ShyamSubramanian/HESM.
Sinkhorn Natural Gradient for Generative Models

We consider the problem of minimizing a functional over a parametric family of probability measures, where the parameterization is characterized via a push-forward structure. An important application of this problem is in training generative adversarial networks. In this regard, we propose a novel Sinkhorn Natural Gradient (SiNG) algorithm which acts as a steepest descent method on the probability space endowed with the Sinkhorn divergence. We show that the Sinkhorn information matrix (SIM), a key component of SiNG, has an explicit expression and can be evaluated accurately in complexity that scales logarithmically with respect to the desired accuracy. This is in sharp contrast to existing natural gradient methods that can only be carried out approximately. Moreover, in practical applications when only Monte-Carlo type integration is available, we design an empirical estimator for SIM and provide the stability analysis. In our experiments, we quantitatively compare SiNG with state-of-the-art SGD-type solvers on generative tasks to demonstrate its efficiency and efficacy of our method.
Infinite staircases in the symplectic embedding problem for four-dimensional ellipsoids into polydisks

We study the symplectic embedding capacity function Cβ for ellipsoids E(1,α)⊂ℝ4 into dilates of polydisks P(1,β) as both α and β vary through [1,∞). For β=1, Frenkel and Muller showed that Cβ has an infinite staircase accumulating at α=3+22, while for integer β≥2, Cristofaro-Gardiner, Frenkel and Schlenk found that no infinite staircase arises. We show that for arbitrary β∈(1,∞), the restriction of Cβ to [1,3+22] is determined entirely by the obstructions from Frenkel and Muller’s work, leading Cβ on this interval to have a finite staircase with the number of steps tending to ∞ as β→1. On the other hand, in contrast to the results of Cristofaro-Gardiner, Frenkel and Schlenk, for a certain doubly indexed sequence of irrational numbers Ln,k we find that CLn,k has an infinite staircase; these Ln,k include both numbers that are arbitrarily large and numbers that are arbitrarily close to 1, with the corresponding accumulation points respectively arbitrarily large and arbitrarily close to 3+22.
Coulomb branches with complex singularities

We construct 4d superconformal field theories (SCFTs) whose Coulomb branches have singular complex structures. This implies, in particular, that their Coulomb branch coordinate rings are not freely generated. Our construction also gives examples of distinct SCFTs which have identical moduli space (Coulomb, Higgs, and mixed branch) geometries. These SCFTs thus provide an interesting arena in which to test the relationship between moduli space geometries and conformal field theory data. We construct these SCFTs by gauging certain discrete global symmetries of $$ \mathcal{N} $$ = 4 superYang-Mills (sYM) theories. In the simplest cases, these discrete symmetries are outer automorphisms of the sYM gauge group, and so these theories have lagrangian descriptions as $$ \mathcal{N} $$ = 4 sYM theories with disconnected gauge groups.
From noncommutative string / membrane to ordinary ones

We discuss origin of equivalence between noncommutative and ordinary Yang-Mills from point of view of string theory. Working in BRST/hamiltonian framework first we investigate string model in the decoupling limit and show that change of variables and applying the conversion of constraints of decoupled string theory gives commuting coordinates on the D-brane. Also, we discuss algebra of constraints in general case and show the ways of having commutative coordinates without going to decoupling limit. It could be argued that noncommutative string in B-field is equivalent to the commutative model. We investigate the case of the membrane ending on the M-5-brane in constant C-field and discuss noncommutative/commutative equivalence in this case.
Small Near-Earth Asteroids in the Palomar Transient Factory Survey: A Real-Time Streak-detection System

Near-Earth asteroids (NEAs) in the 1–100 meter size range are estimated to be ~1,000 times more numerous than the ~15,000 currently cataloged NEAs, most of which are in the 0.5–10 kilometer size range. Impacts from 10–100 meter size NEAs are not statistically life-threatening, but may cause significant regional damage, while 1–10 meter size NEAs with low velocities relative to Earth are compelling targets for space missions. We describe the implementation and initial results of a real-time NEA-discovery system specialized for the detection of small, high angular rate (visually streaked) NEAs in Palomar Transient Factory (PTF) images. PTF is a 1.2-m aperture, 7.3 deg^2 field of view (FOV) optical survey designed primarily for the discovery of extragalactic transients (e.g., supernovae) in 60-second exposures reaching ~20.5 visual magnitude. Our real-time NEA discovery pipeline uses a machine-learned classifier to filter a large number of false-positive streak detections, permitting a human scanner to efficiently and remotely identify real asteroid streaks during the night. Upon recognition of a streaked NEA detection (typically within an hour of the discovery exposure), the scanner triggers follow-up with the same telescope and posts the observations to the Minor Planet Center for worldwide confirmation. We describe our 11 initial confirmed discoveries, all small NEAs that passed 0.3–15 lunar distances from Earth. Lastly, we derive useful scaling laws for comparing streaked-NEA-detection capabilities of different surveys as a function of their hardware and survey-pattern characteristics. This work most directly informs estimates of the streak-detection capabilities of the Zwicky Transient Facility (ZTF, planned to succeed PTF in 2017), which will apply PTF's current resolution and sensitivity over a 47-deg^2 FOV.
AN OPTICAL SURVEY OF THE PARTIALLY EMBEDDED YOUNG CLUSTER IN NGC 7129

NGC 7129 is a bright reflection nebula located in the molecular cloud complex near l = 105◦.4, b = +9◦. 9,, about 1.15 kpc distant. Embedded within the reflection nebula is a young cluster dominated by a compact grouping of four early-type stars: BD+65°1638 (B3V), BD+65°1637 (B3e), SVS 13 (B5e), and LkHα 234 (B8e). About 80 Hα emission sources brighter than V ~ 23 are identified in the region, many of which are presumably T Tauri star members of the cluster. We also present deep (V ~ 23), optical VR_(C)I_C photometry of a field centered on the reflection nebula and spectral types for more than 130 sources determined from low dispersion, optical spectroscopy. The narrow pre-main sequence evident in the color–magnitude diagram suggests that star formation was rapid and coeval. A median age of about 1.8 Myr is inferred for the Hα and literature-identified X-ray emission sources having established spectral types, using pre-main sequence evolutionary models. Our interpretation of the structure of the molecular cloud and the distribution of young stellar objects is that BD+65°1638 is primarily responsible for evacuating the blister-like cavity within the molecular cloud. LkHα 234 and several embedded sources evident in near-infrared adaptive optics imaging have formed recently within the ridge of compressed molecular gas. The compact cluster of low-mass stars formed concurrently with the early-type members, concentrated within a central radius of ~0.7 pc. Star formation is simultaneously occurring in a semi-circular arc some ~3 pc in radius that outlines remaining dense regions of molecular gas. High dispersion, optical spectra are presented for BD+65°1638, BD+65°1637, SVS 13, LkHα 234, and V350 Cep. These spectra are discussed in the context of the circumstellar environments inferred for these stars.
Quantum tomography for collider physics: illustrations with lepton-pair production

Quantum tomography is a method to experimentally extract all that is observable about a quantum mechanical system. We introduce quantum tomography to collider physics with the illustration of the angular distribution of lepton pairs. The tomographic method bypasses much of the field-theoretic formalism to concentrate on what can be observed with experimental data. We provide a practical, experimentally driven guide to model-independent analysis using density matrices at every step. Comparison with traditional methods of analyzing angular correlations of inclusive reactions finds many advantages in the tomographic method, which include manifest Lorentz covariance, direct incorporation of positivity constraints, exhaustively complete polarization information, and new invariants free from frame conventions. For example, experimental data can determine the entanglement entropy of the production process. We give reproducible numerical examples and provide a supplemental standalone computer code that implements the procedure. We also highlight a property of complex positivity that guarantees in a least-squares type fit that a local minimum of a $$\chi ^{2}$$ statistic will be a global minimum: There are no isolated local minima. This property with an automated implementation of positivity promises to mitigate issues relating to multiple minima and convention dependence that have been problematic in previous work on angular distributions.
Global Existence and Large-Time Behavior of Solutions to the Three-Dimensional Equations of Compressible Magnetohydrodynamic Flows

The three-dimensional equations of compressible magnetohydrodynamic isentropic flows are considered. An initial-boundary value problem is studied in a bounded domain with large data. The existence and large-time behavior of global weak solutions are established through a three-level approximation, energy estimates, and weak convergence for the adiabatic exponent $${\gamma > \frac 32}$$ and constant viscosity coefficients.
Consistent covariate selection and post model selection inference in semiparametric regression

This paper presents a model selection technique of estimation in semiparametric regression models of the type $Y_{i}={\beta}^{\prime}\underline{X}_{i}+f(T_{i})+W_{i}$ , i=1,…,n. The parametric and nonparametric components are estimated simultaneously by this procedure. Estimation is based on a collection of finite-dimensional models, using a penalized least squares criterion for selection. We show that by tailoring the penalty terms developed for nonparametric regression to semiparametric models, we can consistently estimate the subset of nonzero coefficients of the linear part. Moreover, the selected estimator of the linear component is asymptotically normal.
Orthonormal systems in linear spans

We show that any $N$-dimensional linear subspace of $L^2(\mathbb{T})$ admits an orthonormal system such that the $L^2$ norm of the square variation operator $V^2$ is as small as possible. When applied to the span of the trigonometric system, we obtain an orthonormal system of trigonometric polynomials with a $V^2$ operator that is considerably smaller than the associated operator for the trigonometric system itself.
LONG-TERM MEASUREMENTS OF SUNSPOT MAGNETIC TILT ANGLES

Tilt angles of close to 30,600 sunspots are determined using Mount Wilson daily averaged magnetograms taken from 1974 to 2012, and SOHO/MDI magnetograms taken from 1996 to 2010. Within a cycle, more than 90% of sunspots have a normal polarity alignment along the east-west direction following Hale's law. The median tilts increase with increasing latitude (Joy's law) at a rate of ~05 per degree of latitude. Tilt angles of spots appear largely invariant with respect to time at a given latitude, but they decrease by ~09 per year on average, a trend that largely reflects Joy's law following the butterfly diagram. We find an asymmetry between the hemispheres in the mean tilt angles. On average, the tilts are greater in the Southern than in the Northern Hemisphere for all latitude zones, and the differences increase with increasing latitude.
Cosmic Reionization On Computers: Reionization Histories of Present-day Galaxies

We examine the reionization history of present-day galaxies by explicitly tracing the building blocks of halos from the Cosmic Reionization On Computers project. We track dark matter particles that belong to $z=0$ halos to trace the neutral fractions at corresponding positions during rapid global reionization. The resulting particle reionization histories allow us to explore different definitions of a halo's reionization redshift and to account for the neutral content of the interstellar medium. Consistent with previous work, we find a systematic trend of reionization redshift with mass - present day halos with higher masses have earlier reionization times. Finally, we quantify the spread of reionization times within each halo, which also has a mass dependence.
Stationary and convergent strategies in Choquet games

If Nonempty has a winning strategy against Empty in the Choquet game on a space, the space is said to be a Choquet space. Such a winning strategy allows Nonempty to consider the entire finite history of previous moves before making each new move; a stationary strategy only permits Nonempty to consider the previous move by Empty. We show that Nonempty has a stationary winning strategy for every second countable T1 Choquet space. More generally, Nonempty has a stationary winning strategy for any T1 Choquet space with an open-finite basis. We also study convergent strategies for the Choquet game, proving the following results. A T1 space X is the open continuous image of a complete metric space if and only if Nonempty has a convergent winning strategy in the Choquet game on X. A T1 space X is the open continuous compact image of a metric space if and only if X is metacompact and Nonempty has a stationary convergent strategy in the Choquet game on X. A T1 space X is the open continuous compact image of a complete metric space if and only if X is metacompact and Nonempty has a stationary convergent winning strategy in the Choquet game on X.
A zoo of growth functions of mapping class sets

Suppose X and Y are finite complexes, with Y simply connected. Gromov conjectured that the number of mapping classes in [X,Y ] which can be realized by L-Lipschitz maps grows asymptotically as Lα, ...
Global Market Conditions and Systemic Risk

This article examines several key global market conditions, such as a proxy for market uncertainty and measures of interbank funding stress, to assess financial volatility and the likelihood of crisis. Using Markov regime-switching techniques, it shows that the Lehman Brothers failure was a watershed event in the crisis, although signs of heightened systemic risk could be detected as early as February 2007. In addition, we analyse the role of global market conditions to help determine when governments should begin to exit their extraordinary public support measures.
PatchAttack: A Black-box Texture-based Attack with Reinforcement Learning

Patch-based attacks introduce a perceptible but localized change to the input that induces misclassification. A limitation of current patch-based black-box attacks is that they perform poorly for targeted attacks, and even for the less challenging non-targeted scenarios, they require a large number of queries. Our proposed PatchAttack is query efficient and can break models for both targeted and non-targeted attacks. PatchAttack induces misclassifications by superimposing small textured patches on the input image. We parametrize the appearance of these patches by a dictionary of class-specific textures. This texture dictionary is learned by clustering Gram matrices of feature activations from a VGG backbone. PatchAttack optimizes the position and texture parameters of each patch using reinforcement learning. Our experiments show that PatchAttack achieves \({>}99\%\) success rate on ImageNet for a wide range of architectures, while only manipulating \(3\%\) of the image for non-targeted attacks and \(10\%\) on average for targeted attacks. Furthermore, we show that PatchAttack circumvents state-of-the-art adversarial defense methods successfully. The code is publicly available here.
Random Finite Set Theory and Centralized Control of Large Collaborative Swarms

Controlling large swarms of robotic agents presents many challenges, including, but not limited to, computational complexity due to a large number of agents, uncertainty in the functionality of eac...
Metabolic Contributions of an Alphaproteobacterial Endosymbiont in the Apicomplexan Cardiosporidium cionae.

Apicomplexa is a diverse protistan phylum composed almost exclusively of metazoan-infecting parasites, including the causative agents of malaria, cryptosporidiosis, and toxoplasmosis. A single apicomplexan genus, Nephromyces, was described in 2010 as a mutualist partner to its tunicate host. Here we present genomic and transcriptomic data from the parasitic sister species to this mutualist, Cardiosporidium cionae, and its associated bacterial endosymbiont. Cardiosporidium cionae and Nephromyces both infect tunicate hosts, localize to similar organs within these hosts, and maintain bacterial endosymbionts. Though many other protists are known to harbor bacterial endosymbionts, these associations are completely unknown in Apicomplexa outside of the Nephromycidae clade. Our data indicate that a vertically transmitted α-proteobacteria has been retained in each lineage since Nephromyces and Cardiosporidium diverged. This α-proteobacterial endosymbiont has highly reduced metabolic capabilities, but contributes the essential amino acid lysine, and essential cofactor lipoic acid to C. cionae. This partnership likely reduces resource competition with the tunicate host. However, our data indicate that the contribution of the single α-proteobacterial endosymbiont in C. cionae is minimal compared to the three taxa of endosymbionts present in the Nephromyces system, and is a potential explanation for the virulence disparity between these lineages.
Unemployment Insurance Claims and COVID-19

Abstract We explore the effect of various factors on interstate differences in weekly unemployment insurance claims, focusing specifically on the determinants over the initial period of the pandemic in the U.S. We consider the effects of COVID-19 cases, state policies enacted in response to COVID-19, relevant provisions of Federal Coronavirus Aid, Relief and Economic Security (CARES) legislation, and the nature of state economies. We find that during the initial weeks of the pandemic, unemployment claims were driven by consumer reactions to the coronavirus. We find that over the March 21-April 25 period states with greater employment in industries most affected by the virus and which issued orders closing nonessential businesses experienced greater weekly unemployment claims. We find mixed evidence that unemployment benefits affect the number of unemployment claims. However, we find no evidence that the ability to work at home mitigated the increase in unemployment rates during this period, nor evidence that the CARES Act’s Payroll Protection Program influenced the level of new unemployment claims.
A Deep intronic variant activates a pseudoexon in the mtm1 gene in a family with x-linked myotubular myopathy

We report a novel intronic variant in the MTM1 gene in 4 males in a family with severe X-linked myotubular myopathy. The A>G variant in deep intronic space activates a cryptic 5' donor splice site resulting in the inclusion of a 48-bp pseudoexon into the mature MTM1 mRNA. The variant is present in all affected males, absent in unaffected males, and heterozygous in the mother of the affected males. The included intronic sequence contains a premature stop codon, and experiments using a translational inhibitor indicate that the mutant mRNAs undergo nonsense-mediated decay. We conclude that affected males produce no, or low, levels of MTM1 mRNA likely leading to a significant reduction of myotubularin-1 protein resulting in the severe neonatal myopathy present in this family. The study highlights the need to consider noncoding variants in genomic screening in families with X-linked myotubular myopathy.
Ab Initio Hydrogen Dynamics and the Morphology of Voids in Amorphous Silicon

This paper presents an $ab$ $initio$ study of hydrogen dynamics inside nanometer-size voids in $a$-Si within the framework of the density-functional theory for a varying hydrogen load of 10 to 30 H atoms/void at the low and high temperature of 400 K and 700 K, respectively. Using the local density approximation and its generalized-gradient counterpart, the dynamics of hydrogen atoms inside the voids are examined with an emphasis on the diffusion of H atoms/molecules, and the resulting nanostructural changes of the void surfaces. The results from simulations suggest that the microstructure of the hydrogen distribution on the void surfaces and the morphology of the voids are characterized by the presence of a significant number of monohydride Si-H bonds, along with a few dihydride Si-H$_2$ configurations. The study also reveals that a considerable number of (about 10--45 at.%) total H atoms inside voids can appear as H$_2$ molecules for a hydrogen load of 10--30 H atoms/void. The approximate shape of the voids is addressed from a knowledge of the positions of the void-surface atoms using the convex-hull approximation and the Gaussian broadening of the pseudo-atomic surfaces of Si and H atoms.
Neutrino amplitude decomposition: toward observing the atmospheric-solar wave interference

Observation of the interference between the atmospheric and solar oscillation waves with the correct magnitude would provide another manifestation of the three-generation structure of leptons. As a prerequisite for such analyses we develop a method for decomposing the oscillation S matrix into the atmospheric and solar amplitudes. Though the similar method was recently proposed successfully in vacuum, once an extension into the matter environment is attempted, it poses highly nontrivial problems. Even for an infinitesimal matter potential, inherent mixture of the atmospheric and solar oscillation waves occurs, rendering a simple extension of the vacuum definition untenable. We utilize general kinematic structure as well as analyses of the five perturbative frameworks, in which the nature of matter-dressed atmospheric and solar oscillations are known, to understand the origin of the trouble, how to deal with the difficulty, and to grasp the principle of decomposition. Then, we derive the amplitude decomposition formulas in these frameworks, and discuss properties of the decomposed probabilities. We mostly discuss the $$\nu _{\mu } \rightarrow \nu _{e}$$ channel, but a comparison with the $$\nu _{\mu } \rightarrow \nu _{\tau }$$ channel reveals an interesting difference.
Child Support Enforcement and Child Mortality

This paper explores the potential benefit of enforcements in Child Support policies to child mortality rates. Exploiting the sharp changes in Child Support laws across states and over the years 197...
Computational investigation of blood flow and flow-mediated transport in arterial thrombus neighborhood

A pathologically formed blood clot or thrombus is central to major cardiovascular diseases like heart attack and stroke. Detailed quantitative evaluation of flow and flow-mediated transport processes in the thrombus neighborhood within large artery hemodynamics is crucial for understanding disease progression and assessing treatment efficacy. This, however, remains a challenging task owing to the complexity of pulsatile viscous flow interactions with arbitrary shape and heterogeneous microstructure of realistic thrombi. Here, we address this challenge by conducting a systematic parametric simulation-based study on characterizing unsteady hemodynamics and flow-mediated transport in the neighborhood of an arterial thrombus. We use a hybrid particle—continuum-based finite element approach to handle arbitrary thrombus shape and microstructural variations. Results from a cohort of 50 different unsteady flow scenarios are presented, including unsteady vortical structures, pressure gradient across the thrombus boundary, finite time Lyapunov exponents, and dynamic coherent structures that organize advective transport. We clearly illustrate the combined influence of three key parameters—thrombus shape, microstructure, and extent of wall disease—in terms of: (a) determining hemodynamic features in the thrombus neighborhood and (b) governing the balance between advection, permeation, and diffusion to regulate transport processes in the thrombus neighborhood.
Characterization of FGFR Signaling in Prostate Cancer Stem Cells and Inhibition via TKI treatment

Metastatic castrate-resistant prostate cancer (CRPC) remains uncurable and novel therapies are needed to better treat patients. Aberrant Fibroblast Growth Factor Receptor (FGFR) signaling has been implicated in advanced prostate cancer (PCa), and FGFR1 is suggested to be a promising therapeutic target along with current androgen deprivation therapy. We established a novel in vitro 3D culture system to study endogenous FGFR signaling in a rare subpopulation of prostate cancer stem cells (CSCs) in the cell lines PC3, DU145, LNCaP, and the induced pluripotent iPS87 cell line. 3D-propagation of PCa cells generated spheroids with increased stemness markers ALDH7A1 and OCT4, while inhibition of FGFR signaling by BGJ398 or Dovitinib decreased cell survival and proliferation of 3D spheroids. The 3D spheroids exhibited altered expression of EMT markers associated with metastasis such as E-cadherin, vimentin and Snail, compared to 2D monolayer cells. TKI treatment did not result in significant changes of EMT markers, however, specific inhibition of FGFR signaling by BGJ398 showed more favorable molecular-level changes than treatment with the multi-RTK inhibitor Dovitinib. This study provides evidence for the first time that FGFR1 plays an essential role in the proliferation of PCa CSCs at a molecular and cellular level, and suggests that TKI targeting of FGFR signaling may be a promising strategy for AR-independent CRPC.
Strict 2-convexity of convex solutions to the quadratic Hessian equation

We prove that convex viscosity solutions to the quadratic Hessian inequality $\sigma_2(D^2u) \geq 1$ are strictly $2$-convex. As a consequence we obtain short proofs of smoothness and interior $C^2$ estimates for convex viscosity solutions to $\sigma_2(D^2u) = 1$, which were proven using different methods in recent works of Guan-Qiu \cite{GQ}, McGonagle-Song-Yuan \cite{MSY} and Shankar-Yuan \cite{SY2}.
From Topological Analyses to Functional Modeling: The Case of Hippocampus

Topological data analyses are widely used for describing and conceptualizing large volumes of neurobiological data, e.g., for quantifying spiking outputs of large neuronal ensembles and thus understanding the functions of the corresponding networks. Below we discuss an approach in which convergent topological analyses produce insights into how information may be processed in mammalian hippocampus---a brain part that plays a key role in learning and memory. The resulting functional model provides a unifying framework for integrating spiking data at different timescales and following the course of spatial learning at different levels of spatiotemporal granularity. This approach allows accounting for contributions from various physiological phenomena into spatial cognition---the neuronal spiking statistics, the effects of spiking synchronization by different brain waves, the roles played by synaptic efficacies and so forth. In particular, it is possible to demonstrate that networks with plastic and transient synaptic architectures can encode stable cognitive maps, revealing the characteristic timescales of memory processing.
Unintended Positive Complementarity: Why International Criminal Court Investigations May Increase Domestic Human Rights Prosecutions

The International Criminal Court (ICC) is controversial, acutely so in Africa. The first thirty-nine people it indicted were all African. It did not open any formal investigations outside Africa until the 2016 decision to investigate conduct related to the 2008 Georgia-Russia war. The first three notifications of withdrawal from the ICC Statute, each made in 2016, were by Burundi, South Africa, and Gambia. While South Africa and Zambia reversed their initial intentions, Burundi in fact became the first state party to withdraw from the ICC in October 2017. These maneuvers are closely connected to country-specific political and legal considerations, but they overlap with concerns expressed by governments in other countries including Kenya and Namibia. Among these concerns is that “the ICC has become the greatest threat to Africa's sovereignty, peace and stability,” and that “the ICC is a colonial institution under the guise of international justice.”
Governance, Conference Calls and CEO Compensation

We study the relations between governance mechanisms (internal and external), conference call voluntary disclosures (incidence and length), and CEO compensation using hand-collected data on conference calls, corporate governance, and compensation. We hypothesize and show that institutions push for more frequent and longer conference calls in order to obtain more information with which to evaluate their investment. While independent directors push to hold conference calls, they may also prefer to have shorter conference calls to avoid potential lawsuits, proprietary costs, and/or loss of reputation that can arise from releasing too much information. Entrenched executives seek to minimize risk (such as employment and/or litigation risk) by limiting the length of conference calls or by avoiding conference calls altogether. In addition, contrary to recently proposed hypotheses, we find that executives do not receive additional compensation for bearing the risks of holding voluntary conference calls.
Causal Inference in Civil Rights Litigation

TABLE OF CONTENTS I. REGRESSION'S DIFFICULTIES AND THE ABSENCE OF A CAUSAL INFERENCE FRAMEWORK 540 A. What Is Regression? 540 B. Problems with Regression: Bias, Ill-Posed Questions, and Specification Issues 543 1. Bias of the Analyst 544 2. Ill-Posed Questions 544 3. Nature of the Model 545 4. One Regression, or Two? 555 C. The Fundamental Problem: Absence of a Causal Framework 556 II. POTENTIAL OUTCOMES: DEFINING CAUSAL EFFECTS AND BEYOND 557 A. Primitive Concepts: Treatment, Units, and the Fundamental Problem 558 B. Additional Units and the Non-Interference Assumption 560 C. Donating Values: Filling in the Missing Counterfactuals 562 D. Randomization: Balance in Background Variables 563 E. Observational Studies: Challenges and Some Ways To Address Them 565 F. The Need for Lots of Background Variables 573 III. POTENTIAL OUTCOMES IN THE CIVIL RIGHTS LITIGATION SETTING 575 A. In General 576 1. Identifying Primitive Concepts. 576 2. A Tug-of-War: The Need for Background Variables Versus the Desire To Detect Discrimination. 581 B. Specific Contexts 583 1. Capital Punishment. 583 2. Employment Discrimination. 588 3. Causation and Section 2 of the Voting Rights Act 590 IV. CONCLUSION 597 "If they can get you asking the wrong questions, they don't have to worry about answers." -- Thomas Pynchon (1) In modern litigation, courts, attorneys, and expert witnesses use statistics in the hope of shedding light on questions of causation. This is particularly true in the civil rights context, where repetition of similar events makes the use of data analysis techniques attractive. The dialogue between law and quantitative methods in the civil rights area has lasted for decades, but few would characterize the relationship as happy. The disquiet is evident on both sides. As early as 1980, legal commentators concluded that many courts disregarded a substantial portion of statistical analyses they encountered in the employment discrimination context. (2) I Twenty-five years later, a survey of Title VII (3) cases demonstrated that little has changed. (4) On the quantitative end, innovation has stagnated. During the decade or so that the Supreme Court was placing its imprimatur on statistics in general and regression in particular as appropriate forms of evidence in Title VII cases, (5) the academy was responding with scholarly examinations of quantitative issues arising in employment discrimination, (6) capital punishment, (7) redistricting, (8) and other contexts. (9) Quantitative analysts were convening panels and holding symposia to make recommendations to improve judicial understanding and use of statistical methods in litigation. (10) Those recommendations were ignored, (11) however, and a perusal of the hornbooks and looseleafs discussing the use of statistics as evidence in civil rights litigation suggests that the field is fixated on methods introduced decades ago, particularly regression, (12) despite judicial dissatisfaction. …
Why RICO's Extraterritorial Reach is Properly Coextensive with the Reach of its Predicates

Advocates and courts have historically adopted an unnecessarily dualistic approach to the extraterritorial application of RICO. At one poll are those suggesting the statute absolutely cannot be applied extraterritorially because it does not announce congressional intention for such application. At the other, there are those suggesting that Congress has manifested clear intention that the statute be applied extraterritorially in a wholesale fashion. As is so often the case, neither extreme is merited, and the truth is in the middle. The Second Circuit struck the proper balance and recognized both the length and the limits for redressing extraterritorial conduct inherent in the RICO statute itself. Unless Congress amends the language of the statute, the “coextensive with predicate acts” approach is best for faithfully determining its extraterritorial reach on a case-by-case basis. It allows potential plaintiffs and prosecutors the latitude Congress intended, based on the plain language of the statute, while restraining them from going any further. As a practical matter, it also permits prosecutors and plaintiffs to adequately confront the injurious behavior of United States citizens, on the one hand, while protecting their interests, on the other. If more is needed in light of present and developing transnational threats, Congress should act decisively to broaden RICO’s extraterritorial scope. Perhaps a legislative remedy is needed. Perhaps one is coming. Unless and until it comes, though, the “coextensive with predicate acts” approach propounded by the Second Circuit provides the clear, logical, and just way forward in light of RICO’s language and purpose. Moreover, it affords the statute the amplitude Congress intended to meet the significant international threats it is uniquely capable of redressing. It permits full, but not reckless, deployment of this “unusually potent weapon” at a time when improper and impractical restraint would be greatly detrimental to America’s vital interests.
Efficiency-Adjusted Public Capital and Growth

Summary This paper constructs an efficiency-adjusted public capital stock series and re-examines the public capital and growth relationship. The paper also examines the effects of four specific stages of the public investment process—appraisal, selection, implementation and evaluation—on capital accumulation and growth. The results show that public capital is a significant contributor to economic growth. The quality of public investment, as measured by variables capturing the adequacy of project selection and implementation, is statistically significant in explaining variations in economic growth, a result mainly driven by low-income countries.
Technical financial analysis tools for Stata

In this article, we provide four financial technical analysis tools: moving averages, Bollinger bands, moving-average convergence divergence, and the relative strength index. The tftools command is used with four subcommands, each referring to a technical analysis tool: bollingerbands, macd, movingaverage, and rsi. We provide examples for each tool. tftools allows researchers to backtest their own investment strategies and will be of interest to investors, researchers, and students of finance.
The Relationship between Capital and Earnings in Banking.

ACCORDING TO CONVENTIONAL WISDOM in banking, a higher capital-asset ratio (CAR) is associated with a lower after-tax return on equity (ROE). The arguments in favor of this hypothesized negative relationship between capital and earnings have intuitive appeal and are consistent with standard oneperiod models of perfect capital markets with symmetric inforrnation between a bank and its investors. A higher capital ratio tends to reduce the risk on equity and therefore lowers the equilibrium expected return on equity required by investors. In addition, a higher CAR lowers after-tax earnings by reducing the tax shield provided by the deductibility of interest payments. Moreover, the reduced risk from a higher capital ratio may depress earnings by lowering the value of access to federal deposit insurance that at best imperfectly prices risk. Despite these arguments, the data on U.S. banks in the mid-to-late 1980s tell a very different story. Book values of CAR and ROE are positively related, and this relationship is both statistically and economically significant. As shown below, the positive relationship between CAR and ROE holds both cross-sectionally and over time, holds when lags are included, and becomes even stronger when an extensive set of control variables is added to the regressions. There are a number of potential explanations for the positive capital-earnings reThe opinions expressed do not necessarily reflect those of the Board of Governors or its staff. The author thanks Alan Greenspan for suggesting the original idea for this research, and the anonymous referees for making numerous suggestions that improved the paper. The author also thanks Sankar Acharya, Mark Carey, Sally Davies, Ed Ettin, Gary Gorton, David Jones, Pat McAllister, Myron Kwast, Jim O'Brien, Rich Rosen, and Greg Udell for helpful comments and thanks John Leusner, Jalal Akhavein, and Joe Scalise for outstanding research assistance.
Outside Blockholders' Monitoring of Management and Debt Financing: An Alternative Perspective

Liao (2015) argues that the monitoring by large outside shareholders (blockholders) exacerbates the conflict between debt and equity and in turn affects the choice and structure of debt financing. The study contends that private debt is more immune to the increase in debt-equity conflict. Consistent with this argument, companies with outside blockholders are inclined to issue private debt over public debt. Further, private debt exhibits less price protection but relies on more protective covenants than does public debt. The findings are interesting and intuitive. I evaluate the economic arguments in the paper and discuss some of the challenges that the study faces. My conclusion is that the interpretation of the results is more complex than the one the study presents. I offer a broader framework that can be used to shed light on why the governance structure combines equity blockholders and private debt issuance. I also discuss several questions to be addressed by future research.
Long memory in volatility and trading volume

Abstract We use fractionally-integrated time-series models to investigate the joint dynamics of equity trading volume and volatility. Bollerslev and Jubinski (1999) show that volume and volatility have a similar degree of fractional integration, and they argue that this evidence supports a long-run view of the mixture-of-distributions hypothesis. We examine this issue using more precise volatility estimates obtained using high-frequency returns (i.e., realized volatilities). Our results indicate that volume and volatility both display long memory, but we can reject the hypothesis that the two series share a common order of fractional integration for a fifth of the firms in our sample. Moreover, we find a strong correlation between the innovations to volume and volatility, which suggests that trading volume can be used to obtain more precise estimates of daily volatility for cases in which high-frequency returns are unavailable.
A New I Do: Towards a Marriage-Neutral Income Tax

The federal income tax system treats married couples as if each spouse earned approximately one-half of the couple's combined income through a mechanism called "income splitting. " For many one-earner and unequal-earner couples, income splitting produces a significant advantage, a "marriage bonus," by shifting income from higher to lower rate brackets. Marriage-based income splitting relies on a presumption that marriage is a good indicator of economic unity between two taxpayers. It is not. Marriage does not require spousal sharing, and many unmarried couples share everything they earn. As a result, the current system extends the benefit of income splitting to some taxpayers who do not deserve it while withholding it from others who do. Because marriage is a poor proxy for economic unity, this Article proposes a new eligibility criterion for income-splitting: only couples legally committed to sharing their income, regardless of marital status, would be permitted to file jointly. * Assistant Professor of Law, University of Richmond School of Law. B.A., Yale University; J.D., New York University School of Law. Copyright © 2006 Shari Motro. I am thankful to Harry Balian, Micah Burch, Yair Benjamini, Lawrence Fleischer, Beverly Gage, James Gibson, Mary Heen, Steve Johnson, Corinna Barrett Lain, Jeremy Matz, Anna Pomykala, Alex Raskolnikov, Deborah Schenk, Christopher Smith, Mary Kelly Tate, Dennis Ventry, and Lawrence Zelenak for their helpful comments and suggestions on earlier drafts of this Article. I am also thankful to my Richmond research assistants Naomi Andrews, Katharine Fuegi, and Cuyler Lovett and to my student Andy Tank, whose persistent questions led me to solve a critical piece of this puzzle. A summer research grant from the University of Richmond School of Law helped fund this work.
Neutrino Physics from New Measurements

Emergence of neutrino physics is fueled by the recent growth in quality and quantity of experimental data, yet, there are still open questions. How much can the determination of mixing parameters be improved? Can we improve bounds on θ13 before experiments designed specifically for this parameter start? How well can we determine or limit sterile fraction of neutrino flux from sun and sterile mixing angle? We examine the impact of outcome from new measurements in the context of providing answers to these questions.
Are Debt and Incentive Compensation Substitutes in Controlling the Free Cash Flow Agency Problem

This paper investigates the governance implications of a firm s capital structure and managerial incentive compensation in controlling the free cash flow agency problem. The results suggest: debt and executive stock options act as substitutes in attenuating a firm s free cashflow problem; failure to incorporate the substitutability and endogeneity leads to underestimates of the magnitude and economic implication of the disciplinary role of both mechanisms; firm characteristics differ across the prevalence of debt usage versus option usage, suggesting the heterogeneity in the costs and benefits of the monitoring devices; and all the above effects are more pronounced in firms that tend to have more severe agency problem. Agency theory predicts that self-serving managers may make nonvalue-maximizing decisions with internal free cash flow by investing in negative net present value projects for private benefits (Jensen, 1986). This behavior is known as overinvestment associated with the free cash flow agency problem, which reflects the conflicts between shareholders and managers. It is important to analyze effective mechanisms to mitigate this agency problem. These mechanisms can either restrict the available resources for overinvestment or align the interests between shareholders and managers. In this paper, I focus on debt and incentive compensation that represent the two types of devices, respectively. Debt directly reduces the free cash flow due to the precommitment of interest payment. On the other hand, incentive compensation prevents managers from investment overaggressiveness through interest alignment. In addition, these two are influential mechanisms considering the importance of capital structure and compensation structure in a firm's policy decisions. Imposing discipline by setting managerial incentives or adjusting capital structure is relatively easy as compared with other mechanisms. l Previous empirical studies have looked at the effects of debt and incentive compensation separately. For example, Harvey, Lins, and Roper (2004) argue that debt mitigates the free cash flow problem in emerging markets, where overinvestment agency costs are potentially extreme.