cssi/SciSciGPT-SciSciNet huggingface dataset:
EXACT MINIMAX ESTIMATION OF THE PREDICTIVE DENSITY IN SPARSE GAUSSIAN MODELS

We consider estimating the predictive density under Kullback-Leibler loss in an l0 sparse Gaussian sequence model. Explicit expressions of the first order minimax risk along with its exact constant, asymptotically least favorable priors and optimal predictive density estimates are derived. Compared to the sparse recovery results involving point estimation of the normal mean, new decision theoretic phenomena are seen. Suboptimal performance of the class of plug-in density estimates reflects the predictive nature of the problem and optimal strategies need diversification of the future risk. We find that minimax optimal strategies lie outside the Gaussian family but can be constructed with threshold predictive density estimates. Novel minimax techniques involving simultaneous calibration of the sparsity adjustment and the risk diversification mechanisms are used to design optimal predictive density estimates.
Scaling Analysis of Nanowire Phase-Change Memory

This letter analyzes the scaling property of nanowire (NW) phase-change memory (PCM) using analytic and numerical methods. The scaling scenarios of the three widely used NW PCM operation schemes (i.e., constant electric field, voltage, and current) are studied and compared. It is shown that if the device size is downscaled by a factor of 1/k (k >; 1), the operation energy (current) will be reduced by more than k3 (k) times, and the operation speed will be increased by k2 times. It is also shown that more than 90% of operation energy is wasted as thermal flux into substrate and electrodes. We predict that, if the wasted thermal flux is effectively reduced by heat confinement technologies, the energy consumed per reset operation can be decreased from about 1 pJ to less than 100 fJ. It is shown that reducing NW aspect ratio helps decreasing PCM energy consumption. It is revealed that cross-cell thermal proximity disturbance is counter intuitively alleviated by scaling, leading to a desirable scaling scenario.
The role of interactions

Interactions between galaxies are suggested to be a mechanism responsible for feeding Active Galactic Nuclei (AGN). Theoretical models show that interactions are an efficient way to drive gas from the galaxy to the nucleus, however, the observational evidence on this subject is controversial. Here we review results in this field, discuss possible limitations of previous studies and the importance of dealing with selection effects. We also show that there is no significant difference in the percentage of low luminosity AGN and normal galaxies with companions, and discuss possible interpretations of this result.
A two-state mixed hidden Markov model for risky teenage driving behavior

This paper proposes a joint model for longitudinal binary and count outcomes. We apply the model to a unique longitudinal study of teen driving where risky driving behavior and the occurrence of crashes or near crashes are measured prospectively over the first 18 months of licensure. Of scientific interest is relating the two processes and predicting crash and near crash outcomes. We propose a two-state mixed hidden Markov model whereby the hidden state characterizes the mean for the joint longitudinal crash/near crash outcomes and elevated g-force events which are a proxy for risky driving. Heterogeneity is introduced in both the conditional model for the count outcomes and the hidden process using a shared random effect. An estimation procedure is presented using the forward-backward algorithm along with adaptive Gaussian quadrature to perform numerical integration. The estimation procedure readily yields hidden state probabilities as well as providing for a broad class of predictors.
A hybrid multicast-unicast infrastructure for efficient publish-subscribe in enterprise networks

One of the main challenges in building a large scale publish subcribe infrastructure in an enterprise network, is to provide the subscribers with the required information, while minimizing the consumed host and network resources. Typically, previous approaches utilize either IP multicast or point-to-point unicast for efficient dissemination of the information.In this work, we propose a novel hybrid framework, which is a combination of both multicast and unicast data dissemination. Our hybrid framework allows us to take the advantages of both multicast and unicast, while avoiding their drawbacks. We investigate several algorithms for computing the best mapping of publishers' transmissions into multicast and unicast transport.Using extensive simulations, we show that our hybrid framework reduces consumed host and network resources, outperforming traditional solutions. To insure the subscribers interests closely resemble those of real-world settings, our simulations are based on stock market data and on recorded IBM WebShpere subscriptions.
NONATTACKING QUEENS IN A RECTANGULAR STRIP

The function that counts the number of ways to place nonattacking identical chess or fairy chess pieces in a rectangular strip of fixed height and variable width, as a function of the width, is a piecewise polynomial which is eventually a polynomial and whose behavior can be described in some detail. We deduce this by converting the problem to one of counting lattice points outside an affinographic hyperplane arrangement, which Forge and Zaslavsky solved by means of weighted integral gain graphs. We extend their work by developing both generating functions and a detailed analysis of deletion and contraction for weighted integral gain graphs. For chess pieces we find the asymptotic probability that a random configuration is nonattacking, and we obtain exact counts of nonattacking configurations of small numbers of queens, bishops, knights, and nightriders.
A Lie algebraic approach to the Kondo problem

Abstract The Kondo problem is approached using the unitary Lie algebra of spin-singlet fermion bilinears. In the limit when the number of values of the spin N goes to infinity the theory approaches a classical limit, which still requires a renormalization. We determine the ground state of this renormalized theory. Then we construct a quantum theory around this classical limit, which amounts to recovering the case of finite N .
Duality and free energy analyticity bounds for few-body Ising models with extensive homology rank

We consider pairs of few-body Ising models where each spin enters a bounded number of interaction terms (bonds) such that each model can be obtained from the dual of the other after freezing k spins on large-degree sites. Such a pair of Ising models can be interpreted as a two-chain complex with k being the rank of the first homology group. Our focus is on the case where k is extensive, that is, scales linearly with the number of bonds n. Flipping any of these additional spins introduces a homologically nontrivial defect (generalized domain wall). In the presence of bond disorder, we prove the existence of a low-temperature weak-disorder region where additional summation over the defects has no effect on the free energy density f(T) in the thermodynamical limit and of a high-temperature region where an extensive homological defect does not affect f(T). We also discuss the convergence of the high- and low-temperature series for the free energy density, prove the analyticity of limiting f(T) at high and low temperatures, and construct inequalities for the critical point(s) where analyticity is lost. As an application, we prove multiplicity of the conventionally defined critical points for Ising models on all { f, d} tilings of the infinite hyperbolic plane, where df/(d + f) > 2. Namely, for these infinite graphs, we show that critical temperatures with free and wired boundary conditions differ, Tc(f)<Tc(w).
An equal area law for holographic entanglement entropy of the AdS-RN black hole

The Anti-de Sitter-Reissner-Nordstrom (AdS-RN) black hole in the canonical ensemble undergoes a phase transition similar to the liquid-gas phase transition, i.e. the isocharges on the entropy-temperature plane develop an unstable branch when the charge is smaller than a critical value. It was later discovered that the isocharges on the entanglement entropy -temperature plane also exhibit the same van der Waals-like structure, for spherical entangling regions. In this paper, we present numerical results which sharpen this similarity between entanglement entropy and black hole entropy, by showing that both of these entropies obey Maxwell’s equal area law to an accuracy of around 1%. Moreover, we checked this for a wide range of size of the spherical entangling region, and the equal area law holds independently of the size. We also checked the equal area law for AdS-RN in 4 and 5 dimensions, so the conclusion is not specific to a particular dimension. Finally, we repeated the same procedure for a similar, van der Waals-like transition of the dyonic black hole in AdS in a mixed ensemble (fixed electric potential and fixed magnetic charge), and showed that the equal area law is not valid in this case. Thus the equal area law for entanglement entropy seems to be specific to the AdS-RN background.
Double-Mode Radial Pulsations among RR Lyrae Stars

Double-mode RR Lyr type stars are important for studies of properties of horizontal-branch stars. In particular, two periods coupled with spectral properties give a mass estimate that is independent of evolutionary models. Here, we present 59 new Galactic double-mode RR Lyr stars found in the LINEAR survey data with the fundamental radial mode and the first overtone exited (RRd stars). These stars may be useful for constraining the mass-metallicity relation for field horizontal-branch stars. Also, new RRd stars found in the LMC by EROS-II are verified. We present the updated Petersen diagram and the distribution of the fundamental mode periods. Comments on selected variable stars from LINEAR and LMC EROS-II surveys are also presented, including very rare objects: the third known mode-switching RR Lyr and a Cepheid pulsating simultaneously in three radial modes.
The Clustering of X-ray Luminous Quasars

The clustering of active galactic nuclei (AGN) sheds light on their typical large (Mpc-scale) environments, which can constrain the growth and evolution of supermassive black holes. Here we measure the clustering of luminous X-ray-selected AGN in the Stripe 82X and XMM-XXL-North surveys around the peak epoch of black hole growth, in order to investigate the dependence of luminosity on large-scale AGN environment. We compute the auto-correlation function of AGN in two luminosity bins, $10^{43}\leq L_X<10^{44.5}$ erg s$^{-1}$ at $z\sim 0.8$ and $L_X\geq 10^{44.5}$ erg s$^{-1}$ at $z\sim 1.8$, and calculate the AGN bias taking into account the redshift distribution of the sources using three different methods. Our results show that while the less luminous sample has an inferred typical halo mass that is smaller than for the more luminous AGN, the host halo mass may be less dependent on luminosity than suggested in previous work. Focusing on the luminous sample, we calculate a typical host halo mass of $\sim 10^{13}$ M$_{\odot}~h^{-1}$, which is similar to previous measurements of moderate-luminosity X-ray AGN and significantly larger than the values found for optical quasars of similar luminosities and redshifts. We suggest that the clustering differences between different AGN selection techniques are dominated by selection biases, and not due to a dependence on AGN luminosity. We discuss the limitations of inferring AGN triggering mechanisms from halo masses derived by large-scale bias.
Modeling the Emission from Turbulent Relativistic Jets in Active Galactic Nuclei

We present a numerical model developed to calculate observed fluxes of relativistic jets in active galactic nuclei. The observed flux of each turbulent eddy is dependent upon its variable Doppler boosting factor, computed as a function of the relativistic sum of the individual eddy and bulk jet velocities, and our viewing angle to the jet. The total observed flux is found by integrating the radiation from the eddies over the turbulent spectrum. We consider jets that contain turbulent eddies that have either standard Kolmogorov or recently derived relativistic turbulence spectra. We also account for the time delays in receiving the emission of the eddies due to their different simulated positions in the jet, as well as due to the varying beaming directions as they turn over. We examine these theoretical light curves and compute power spectral densities (PSDs) for a range of viewing angles, bulk velocities of the jet, and turbulent velocities. These PSD slopes depend significantly on the turbulent velocity, and are essentially independent of viewing angle and bulk velocity. The flux variations produced in the simulations for realistic values of the parameters tested are consistent with the types of variations observed in radio-loud AGN as, for example, recently measured with the Kepler satellite, as long as the turbulent velocities are not too high.
SEARCHES FOR NEW PHYSICS

Current experimental limits for new physics beyond the Standard Model and hints for deviations from Standard Model expectations will be reviewed, highlighting recent results. Possible signals that will be discussed include Higgs bosons, supersymmetric particles, large extra dimensions, new gauge bosons, dynamical symmetry breaking, muon g - 2, rare decays and lepton flavor violation. The discovery potential of the LHC and ILC will be presented, and the impact of discovery on answering fundamental questions of physics will be assessed.
Rethinking Self-Attention: Towards Interpretability in Neural Parsing.

Attention mechanisms have improved the performance of NLP tasks while allowing models to remain explainable. Self-attention is currently widely used, however interpretability is difficult due to the numerous attention distributions. Recent work has shown that model representations can benefit from label-specific information, while facilitating interpretation of predictions. We introduce the Label Attention Layer: a new form of self-attention where attention heads represent labels. We test our novel layer by running constituency and dependency parsing experiments and show our new model obtains new state-of-the-art results for both tasks on both the Penn Treebank (PTB) and Chinese Treebank. Additionally, our model requires fewer self-attention layers compared to existing work. Finally, we find that the Label Attention heads learn relations between syntactic categories and show pathways to analyze errors.
Resistance of high-temperature cuprate superconductors

Cuprate superconductors have many different atoms per unit cell. A large fraction of cells (5–25%) must be modified ('doped') before the material superconducts. Thus it is not surprising that there is little consensus on the superconducting mechanism, despite almost 200 000 papers (Mann 2011 Nature 475 280). Most astonishing is that for the simplest electrical property, the resistance, 'despite sustained theoretical efforts over the past two decades, its origin and its relation to the superconducting mechanism remain a profound, unsolved mystery' (Hussey et al 2011 Phil. Trans. R. Soc. A 369 1626). Currently, model parameters used to fit normal state properties are experiment specific and vary arbitrarily from one doping to the other. Here, we provide a quantitative explanation for the temperature and doping dependence of the resistivity in one self-consistent model by showing that cuprates are intrinsically inhomogeneous with a percolating metallic region and insulating regions. Using simple counting of dopant-induced plaquettes, we show that the superconducting pairing and resistivity are due to phonons.
Dangerous implications of a minimum length in quantum gravity

The existence of a minimum length and a generalization of the Heisenberg uncertainty principle seem to be two fundamental ingredients required in any consistent theory of quantum gravity. In this paper, we show that they would predict dangerous processes which are phenomenologically unacceptable. For example, long-lived virtual super-Planck mass black holes may lead to rapid proton decay. Possible solutions of this puzzle are briefly discussed.
Weyl versus conformal invariance in quantum field theory

We argue that conformal invariance in flat spacetime implies Weyl invariance in a general curved background metric for all unitary theories in spacetime dimensions d ≤ 10. We also study possible curvature corrections to the Weyl transformations of operators, and show that these are absent for operators of sufficiently low dimensionality and spin. We find possible ‘anomalous’ Weyl transformations proportional to the Weyl (Cotton) tensor for d > 3 (d = 3). The arguments are based on algebraic consistency conditions similar to the Wess-Zumino consistency conditions that classify possible local anomalies. The arguments can be straightforwardly extended to larger operator dimensions and higher d with additional algebraic complexity.
Visitors to urban greenspace have higher sentiment and lower negativity on Twitter

With more people living in cities, we are witnessing a decline in exposure to nature. A growing body of research has demonstrated an association between nature contact and improved mood. Here, we used Twitter and the Hedonometer, a world analysis tool, to investigate how sentiment, or the estimated happiness of the words people write, varied before, during, and after visits to San Francisco's urban park system. We found that sentiment was substantially higher during park visits and remained elevated for several hours following the visit. Leveraging differences in vegetative cover across park types, we explored how different types of outdoor public spaces may contribute to subjective well-being. Tweets during visits to Regional Parks, which are greener and have greater vegetative cover, exhibited larger increases in sentiment than tweets during visits to Civic Plazas and Squares. Finally, we analyzed word frequencies to explore several mechanisms theorized to link nature exposure with mental and cognitive benefits. Negation words such as 'no', 'not', and 'don't' decreased in frequency during visits to urban parks. These results can be used by urban planners and public health officials to better target nature contact recommendations for growing urban populations.
Separable elements in Weyl groups

Abstract We define the notion of a separable element in a finite Weyl group, generalizing the well-studied class of separable permutations. We prove that the upper and lower order ideals in weak Bruhat order generated by a separable element are rank-symmetric and rank-unimodal, and that the product of their rank generating functions gives that of the whole group, answering an open problem of Fan Wei. We also prove that separable elements are characterized by pattern avoidance in the sense of Billey and Postnikov.
DNA, human memory, and the storage technology of the 21st century

The sophisticated tools and techniques employed by Nature for purposeful storage of information stand in stark contrast to the primitive and relatively inefficient means used by man. We describe some impressive features of biological data storage, and speculate on approaches to research and development that could benefit the storage industry in the coming decades.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Resonant non-gaussianity

We provide a derivation from first principles of the primordial bispectrum of scalar perturbations produced during inflation driven by a canonically normalized scalar field whose potential exhibits small sinusoidal modulations. A potential of this type has been derived in a class of string theory models of inflation based on axion monodromy. We use this model as a concrete example, but we present our derivations and results for a general slow-roll potential with superimposed modulations. We show analytically that a resonance between the oscillations of the background and the oscillations of the fluctuations is responsible for the production of an observably large non-Gaussian signal. We provide an explicit expression for the shape of this resonant non-Gaussianity. We show that there is essentially no overlap between this shape and the local, equilateral, and orthogonal shapes, and we stress that resonant non-Gaussianity is not captured by the simplest version of the effective field theory of inflation. We hope our analytic expression will be useful to further observationally constrain this class of models.
“Naked” Cronin effect in A + A collisions from SPS to RHIC

Baseline computations of the Cronin effect in nuclear collisions at energies spanning the SPS and the RHIC accelerators are performed in the Glauber-Eikonal model, which ascribes the effect to initial-state incoherent multiple parton scatterings. The model accounts very well for the mid-rapidity Cronin effect in hadron-nucleus collisions in the $\sqrt{s} = 27$ -200 GeV center of mass energy range, and will be extended to nucleus-nucleus collisions. The computations are performed under the assumption that the partons do not interact with the medium produced in the collision. Therefore, medium effects such as energy loss in a quark-gluon plasma may be detected and measured as deviations from the presented baseline computation of the “naked” Cronin effect.
Grafting Seiberg-Witten monopoles.

We demonstrate that the operation of taking disjoint unions of J -holomorphic curves (and thus obtaining new J -holomorphic curves) has a Seiberg-Witten counterpart. The main theorem asserts that, given two solutions (Ai; i), i =0 ;1 of the Seiberg-Witten equations for the Spin c -structures W + Ei = Ei (EiK 1 ) (with certain restrictions), there is a solution (A; ) of the Seiberg-Witten equations for the Spin c -structure WE with E = E0E1 , obtained by \grafting"the two solutions (Ai; i). AMS Classication 53D99, 57R57; 53C27, 58J05
Comparing allosteric transitions in the domains of calmodulin through coarse-grained simulations

Calmodulin (CaM) is a ubiquitous Ca(2+)-binding protein consisting of two structurally similar domains with distinct stabilities, binding affinities, and flexibilities. We present coarse grained simulations that suggest that the mechanism for the domain's allosteric transitions between the open and closed conformations depends on subtle differences in the folded state topology of the two domains. Throughout a wide temperature range, the simulated transition mechanism of the N-terminal domain (nCaM) follows a two-state transition mechanism while domain opening in the C-terminal domain (cCaM) involves unfolding and refolding of the tertiary structure. The appearance of the unfolded intermediate occurs at a higher temperature in nCaM than it does in cCaM consistent with nCaM's higher thermal stability. Under approximate physiological conditions, the simulated unfolded state population of cCaM accounts for 10% of the population with nearly all of the sampled transitions (approximately 95%) unfolding and refolding during the conformational change. Transient unfolding significantly slows the domain opening and closing rates of cCaM, which can potentially influence its Ca(2+)-binding mechanism.
T-S-T Dual Black Hole

The sequence of intertwined T-S-T duality transformations acting on the 4D static uncharged black hole leads to a black hole background with horizon and singularity exchanged. It is shown that this space–time is extendible too. In particular we will see that a string moving into a black hole is dual to a string leaving a white hole. That offers the possibility that a test-string does not see the singularity.
Entropic Forms and Related Algebras

Starting from a very general trace-form entropy, we introduce a pair of algebraic structures endowed by a generalized sum and a generalized product. These algebras form, respectively, two Abelian fields in the realm of the complex numbers isomorphic each other. We specify our results to several entropic forms related to distributions recurrently observed in social, economical, biological and physical systems including the stretched exponential, the power-law and the interpolating Bosons-Fermions distributions. Some potential applications in the study of complex systems are advanced.
Explanatory Item Response Models for Dyadic Data from Multiple Groups

Like other quantitative social scientists, network researchers benefit from pooling information from multiple observed variables to infer underlying (latent) attributes or social processes. Appropr...
Data-driven selection of coarse-grained models of coupled oscillators

This paper introduces a data-driven method for constructing reduced-order closure models for complex dynamical systems. The authors illustrate their approach by inferring precise coarse-grained network models of coupled oscillators.
Rapid charge redistribution leading to core hollowing in a high-intensity ion beam

Recently, the first direct measurement of a full 6D accelerator beam distribution was reported [B. Cathey, S. Cousineau, A. Aleksandrov, and A. Zhukov, Phys. Rev. Lett. 121, 064804 (2018)]. That work observed a correlation between energy and transverse coordinates, for which the energy distribution becomes hollowed near the transverse core. This hollowing is obscured when the 6D phase space is projected onto one- and two-dimensional axes. This article illustrates how a similar structure emerges from simulation of an initially uncorrelated, high density bunched beam as the result of velocity perturbation from initial nonlinear space charge forces. This phenomenon has not been widely recognized in accelerator systems, but parallels can be drawn to observations of laser-ionized nanoclusters and electron sources for diffraction. While this effect provides insight into the origin of the measured core correlation, it does not provide a complete description. A better reproduction of the measured structure can be obtained via self-consistent simulation through the radio-frequency quadrupole.
Scale Aware Adaptation for Land-Cover Classification in Remote Sensing Imagery

Land-cover classification using remote sensing imagery is an important Earth observation task. Recently, land cover classification has benefited from the development of fully connected neural networks for semantic segmentation. The benchmark datasets available for training deep segmentation models in remote sensing imagery tend to be small, however, often consisting of only a handful of images from a single location with a single scale. This limits the models’ ability to generalize to other datasets. Domain adaptation has been proposed to improve the models’ generalization but we find these approaches are not effective for dealing with the scale variation commonly found between remote sensing image collections. We there-fore propose a scale aware adversarial learning frame-work to perform joint cross-location and cross-scale land-cover classification. The framework has a dual discriminator architecture with a standard feature discriminator as well as a novel scale discriminator. We also introduce a scale attention module which produces scale-enhanced features. Experimental results show that the proposed frame-work outperforms state-of-the-art domain adaptation methods by a large margin. The open-sourced codes are available on Github: https://github.com/xdeng7/scale-aware_da.
GuidePro: A multi-source ensemble predictor for prioritizing sgRNAs in CRISPR/Cas9 protein knockouts

Motivation The efficiency of CRISPR/Cas9-mediated protein knockout is determined by three factors: sequence-specific sgRNA activity, frameshift probability, and the characteristics of targeted amino acids. A number of computational methods have been developed for predicting sgRNA efficiency from different perspectives. However, an integrative method that combines all three factors for rational sgRNA selection is still lacking. Results We developed GuidePro, a two-layer ensemble predictor that enables the integration of multiple factors for the prioritization of sgRNAs in protein knockouts. Tested on independent datasets, GuidePro outperforms existing methods and demonstrates consistent superior performance in predicting phenotypes caused by protein loss-of-function, suggesting its robustness for prioritizing sgRNAs in various applications of CRISPR/Cas9 knockouts. Availability GuidePro is available at https://github.com/MDhewei/GuidePro. A web application for prioritizing sgRNAs that target protein-coding genes in human, monkey and mouse genomes is available at https://bioinformatics.mdanderson.org/apps/GuidePro. Supplementary information Supplementary data are available at Bioinformatics online.
Quality of financial information and liquidity

Abstract This paper examines the relationship between liquidity and quality of financial information by analyzing long-term trends in Amihud's (2002) illiquidity measure for firms that restate financial statements. I find that for most income decreasing restatements illiquidity increases several months before restatement announcement and remains at elevated levels one year after restatement. The result is most pronounced for firms listed on NASDAQ. Increase in illiquidity is greater upon restatements due to revenue recognition, those prompted by party other than auditor, those made by larger firms with high volatility of returns and low price levels. Income increasing restatements do not affect information asymmetry of the firm. Overall, my results indicate a positive relationship between quality of financial information and liquidity.
Shame, Regret, and Contract Design

This Article examines whether contract design can influence the post-formation behavior of the non-drafting party. If it can, contract preparers may be able to obtain significant transactional advantages. This Article suggests that several contractual features can be explained in terms of their ability to exploit the cognitive biases of, and to induce particular “advantageous” emotions from, the non-drafting party after the contract has been executed. These features may include arbitration provisions, disclosures in capital letter or bold face type, “reliance” language, and language framing possible losses in particular ways. Contracts can encourage individuals to feel shame, to blame themselves, to believe that contracts are sacred promises that should be specifically performed, to utilize faulty judgment heuristics when determining contract costs, and to rely on misperceived social norms with respect to challenging or breaching contracts. This may influence them not to breach or challenge an otherwise uneconomical, unconscionable, or illegal contract. Consequently, contract preparers may be able to enjoy the benefits of promises that often would not be realized if the non-drafting party were profit-maximizing like the contract preparer.
Spousal influences on parents’ non-market time choices

This paper considers the effect of spouse’s characteristics on time devoted to leisure, child caregiving, and home production of married mothers and fathers using the American Time Use Survey (ATUS). Five spousal variables are considered: the relative wage of the wife compared to her husband, spouse’s weekly hours of employment, and the spouse’s time in three unpaid activities. Each requires instrumentation in order to address issues of endogeneity and possible selection bias. In addition, in order to handle the problem that there is only a single time diary per household, two alternative strategies are explored: out-of-sample prediction and propensity matching. Using either method, the results show little effect of one spouse on the unpaid time use of parents. Most importantly, relative wage does not appear to affect time use choices of parents. There does appear to be a small consistent effect of one’s spouse’s leisure time on own leisure time; husband’s and wife’s leisure time appears to be complementary.
FAA Preemption after Concepcion

AT&T Mobility LLC v. Concepcion is an important case for its holding that the FAA preempts application of state unconscionability doctrine to invalidate an arbitration clause with a class arbitration waiver. But in a number of respects, the effect of Concepcion has been overstated, including its effect on application of state unconscionability doctrine to arbitration clauses. Concepcion does not preempt all or even most state unconscionability doctrine as applied to arbitration agreements. Properly construed, Concepcion preempts state unconscionability doctrine only when that doctrine conditions enforcement of arbitration agreements on procedures inconsistent with “fundamental attributes of arbitration” of the sort illustrated in Concepcion itself ― such as the use of juries, court-monitored discovery, evidentiary rules, and, of course, class arbitration. If, however, the Supreme Court were to construe Concepcion more broadly (or eliminate application of unconscionability to invalidate arbitration clauses altogether), courts would retain some residual authority to police the fairness of arbitration clauses, but only by finding a dispute resolution process not to be arbitration at all.
Sustainable Federal Land Management: Protecting Ecological Integrity and Preserving Environmental Principal

This article explores the application of the principles of sustainability to management of lands and resources under the jurisdiction of the U.S. Forest Service and the Bureau of Land Management. These two agencies operate a mandate to manage the resources under their control to achieve sustained yield. In this context, sustainability has operated to date primarily in an aspirational fashion, as a broad objective of public land management, rather than as a useful management tool or an enforceable constraint on agency management discretion. The article urges the adoption of amendments to the laws under which the Forest Service and the BLM operate to make them more consistent with the core function of sustainability - to ensure that the valuable environmental services provided by the lands and resources these agencies manage remain unimpaired for both present and future generations in the face of both natural disturbances and human use. In particular, it recommends that Congress recognize that federal lands and resources are held by the multiple use agencies in trust for the benefit of present and future generations and that it create a mechanism by which private citizens or public interest groups may sue the agencies if they waste trust assets or otherwise breach their fiduciary obligations to the American people. The article explores what the agencies’ core trust responsibilities should entail and provides examples of management standards that either Congress or the agencies might adopt to codify those obligations to assist judicial review of alleged breaches of fiduciary duty. In particular, it points to the certification processes created by the Forest Stewardship Council and the Fisheries Stewardship Council, coalitions of non-governmental organizations that promote sustainable forest and fisheries management, as possible models for transforming sustainability from an aspirational objective to an enforceable mandate to which the Forest Service and the BLM can be held accountable when they make specific resource management decisions.
The FrobeniusThresholds package for Macaulay2

This article describes the \emph{Macaulay2} package \emph{FrobeniusThresholds}, designed to estimate and calculate $F$-pure thresholds, more general $F$-thresholds, and related numerical invariants arising in the study of singularities in prime characteristic commutative algebra.
Optimal stock trading with personal taxes: Implications for prices and the abnormal January returns

Abstract The tax law confers upon the investor a timing option - to realize capital losses and defer capital gains. With the tax rate on long term gains and losses being about half the short term rate, the law provides a second timing option - to realize losses short term and gains long term, if at all. Our theory and simulation over the 1962–1977 period establish that taxable investors should realize long term gains in high variance stocks and repurchase stock in order to realize potential future losses short term. Tax trading does not explain the small-firm anomaly but predicts a seasonal pattern in trading volume which maps into a seasonal pattern in stock prices, the January anomaly, only if investors are irrational or ignorant of the price seasonality.
The international business cycle as intertemporal coordination failure

Where investments are irreversible and the future is uncertain, people in two countries can make investment decisions that turn out to be mutually inconsistent. I argue that this intertemporal coordination failure explains international business cycles in a two-currency-area setting with a floating foreign exchange rate. The sequence of events starts with an expansionary domestic monetary shock, which decreases the domestic real interest rate. Facing low transactions costs, people spend the new money relatively early in the foreign exchange market and in the foreign market for loanable funds. Domestic monetary expansion thereby changes the relative prices of domestic and foreign goods and also of goods of earlier and later stages of production. The relative price changes lead to intertemporal and international coordination failures once the monetary expansion ends and relative prices change. Domestic monetary policy thereby causes the comovement across different currency areas we observe of business cycles.
Economic crisis and accounting evolution

We study changes in financial reporting around economic crises from a historical perspective through the lens of punctuated equilibrium evolution. Historical evidence and contemporary economic analyses indicate that corporate financial reporting plays a minor role in precipitating economic crises but might amplify them. Economic crises likely play a role similar to major shocks in biological environments by selecting accounting practices, accounting principles, firms and regulatory institutions for survival based on how well they adapt to post-crisis environments. Conscious attempts to improve accounting in the wake of crises, whether through market or political forces, may not prove as beneficial as hoped because we currently know far too little about the causes of economic crises or the consequences of abrupt changes to complex adaptive systems such as accounting. We outline several questions for future research that would increase our knowledge about these fundamental issues.
From the New Wave to the New Hollywood: The Life Cycles of Important Movie Directors from Godard and Truffaut to Spielberg and Eastwood

Two great movie directors were both born in 1930. One of them, Jean-Luc Godard, revolutionized filmmaking during his 30s and declined in creativity thereafter. In contrast, Clint Eastwood did not direct his first movie until he had passed the age of 40 and did not emerge as an important director until after he was 60. This dramatic difference in life cycles was not accidental, but was a characteristic example of a pattern that has been identified across the arts: Godard was a conceptual innovator who peaked early, whereas Eastwood was an experimental innovator who improved with experience. This article examines the goals, methods, and creative life cycles of Godard, Eastwood, and eight other directors who were the most important filmmakers of the second half of the twentieth century. Francis Ford Coppola, Stanley Kubrick, Stephen Spielberg, and Francois Truffaut join Godard in the category of conceptual young geniuses, while Woody Allen, Robert Altman, John Cassavetes, and Martin Scorsese are cla...
Detecting news in aggregate accounting earnings: implications for stock market valuation

How much news is there in aggregate accounting earnings? I provide evidence that earnings changes at the stock market level are correlated with new information about not only expected future cash flows but also discount rates. A comprehensive investigation of the link to discount rates reveals that aggregate earnings changes are tied to news about all components of the expected future stock market return, i.e., the real riskless rate, expected inflation, and the expected equity risk premium. Over the sample period studied, cash flow news and discount rate news in aggregate earnings changes covary positively and have offsetting impacts on stock market prices. As a result, stock market prices appear to be insensitive to aggregate earnings changes. The findings highlight the importance of separating cash flow news from discount rate news when evaluating the information content of accounting earnings at the stock market level. Overall, my study sheds new light on the informativeness and relevance of accounting earnings for valuation at the stock market level.
Internal governance and performance: Evidence from when external discipline is weak

Abstract The effect of internal governance on performance is potentially economically significant but may be difficult to identify because of confounding external disciplinary mechanisms and the endogenous choice of internal governance. This study addresses those difficulties by using nonprofit hospitals as an economic environment with muted external disciplinary mechanisms and instrumenting for internal governance using governance spillovers of geographically local public firms. Using patient heart attack survival as a measure of performance, a one standard deviation increase in strength of internal governance reduces the probability of death by 0.89 percentage points after controlling for patient characteristics.
When you say nothing at all: The predictive power of student effort on surveys

Abstract Character traits and noncognitive skills are important for human capital development and long-run life outcomes. Research in economics and psychology now shows this convincingly. But research into the exact determinants of noncognitive skills has been slowed by a common data limitation: most large-scale datasets do not contain adequate measures of noncognitive skills. This is particularly problematic in education policy evaluation. We demonstrate that within any survey dataset, there is important latent information that can be used as a proxy measure of noncognitive skills. Specifically, we examine the amount of conscientious effort that students exhibit on surveys, as measured by their item response rates. We use six nationally-representative, longitudinal surveys of American youth. We find that the percentage of questions skipped during the baseline year when respondents were adolescents is a significant predictor of later-life educational attainment, net of cognitive ability. Insofar as item response rates affect employment and income, they do so through their effect on educational attainment. The pattern of findings gives compelling reasons to view item response rates as a promising behavioral measure of noncognitive skills for use in future research. We posit that response rates are a measure of conscientiousness, though additional research is required to determine what exact noncognitive skills are being captured by item response rates.
Consumer Learning, Switching Costs, and Heterogeneity: A Structural Examination

This paper develops and estimates a model of forward-looking consumer learning with switching costs using household level scanner data from a frequently purchased product category. This is novel because current models of consumer purchase behavior assume that only one of these types of dynamics is present, not both at the same time. My model estimates support the presence of both learning and switching costs in this product category. The estimates show that before consuming new products, consumers are unsure of their tastes for them, and subsequently learn their tastes by purchase and consumption of new products. Switching costs are large, comprising roughly 30 percent of the cost of a medium sized package of the product. Additionally, the model incorporates very rich individual level unobserved heterogeneity in price sensitivities, tastes, and switching costs, and the amount by which consumers learn. To show that my model produces different implications than a model with learning or switching costs only, I estimate two more specifications, one without each type of dynamics, and simulate counterfactuals that are of interest to managers and policymakers. I find that intertemporal elasticities are underestimated when either type of dynamics is left out, by as much as 90%. Informative advertising is also affected by the presence of switching costs, although the direction of the bias is not signed. Leaving out dynamics also has a large impact on long-term elasticities, which are used by antitrust policymakers to evaluate the impact of mergers. When learning is ignored, cross elasticities are underestimated by as much as 45%. When switching costs are ignored, both own and cross elasticities are underestimated.
Khovanov homology detects the figure-eight knot

Using Dowlin's spectral sequence from Khovanov homology to knot Floer homology, we prove that reduced Khovanov homology (over $\mathbb{Q}$) detects the figure-eight knot.
Devolution and the civil service: A biographical study

Since devolution, the United Kingdom has evolved not only in terms of political representation but also in terms of the relationships between civil servants in each of its regions and nations. In t...
Does trade liberalization harm the environment? A new test

Recent events such as the NAFTA and the completion of the Uruguay Round have raised concern over the impact of trade liberalization on the environment. In particular, it is believed that less stringent environmental standards in developing countries will give them a comparative advantage in pollutionintensive goods. Using single equation models, existing empirical studies have found either no relationship between environment and trade flows, or a positive relationship between trade liberalization and the environment. This paper develops a simultaneous-equations model to estimate this relationship, directly incorporating the effects of openness on growth of income, and of income growth on environmental damage. A two-good trade model with endogenous factor supply is estimated using pooled provincial data on Chinese water pollution from 1987-1995. Estimation of this model reveals that trade liberalization directly aggravates environmental damage via its influence on the terms of trade, but indirectly mitigates it via its effect on income growth. Simulations suggest that trade reform during the period may have had a net beneficial impact on emissions growth.
Taking Issue with Issue Advocacy

Professor Lillian BeVier has written a provocative article that reemphasizes and extends many of her well-known, laissez-faire ideas about campaign finance.' I am most persuaded by her argument that recent efforts to distinguish election-related and political spending would not by themselves be sufficient to avoid the far-reaching analysis of Buckley v. Valeo.2 Professor BeVier's larger and more important thesis, however, is that the arguments of "regulationists" for restricting issue advocacy are both theoretically and empirically deficient.3 In this Comment, I wish to do three things:
Long‐Run Corporate Tax Avoidance

We develop and describe a new measure of long‐run corporate tax avoidance that is based on the ability to pay a low amount of cash taxes per dollar of pre‐tax earnings over long time periods. We label this measure the “long‐run cash effective tax rate.” We use the long‐run cash effective tax rate to examine (1) the extent to which some firms are able to avoid taxes over periods as long as ten years, and (2) how predictive one‐year tax rates are for long‐run tax avoidance. In our sample of 2,077 firms, we find there is considerable cross‐sectional variation in tax avoidance. For example, approximately one‐fourth of our sample firms are able to maintain long‐run cash effective tax rates below 20 percent, compared to a sample mean tax rate of approximately 30 percent. We also find that annual cash effective tax rates are not very good predictors of long‐run cash effective tax rates and, thus, are not accurate proxies for long‐run tax avoidance. While there is some evidence of persistence in annual cash effec...