cssi/SciSciGPT-SciSciNet huggingface dataset:
Existence of CMC Cauchy surfaces and spacetime splitting

In this paper, we review results on the existence (and nonexistence) of constant mean curvature spacelike hypersurfaces in the cosmological setting, and discuss the connection to the spacetime splittng problem. It is a pleasure to dedicate this paper to Robert Bartnik, who has made fundamental contributions to this area.
Development of hypersonic engine seals - Flow effects of preload and engine pressures

A new type of engine seal is being developed to meet the needs of advanced hypersonic engines. A seal braided of emerging high temperature ceramic fibers comprised of a sheath-core construction was selected for study based on its low leakage rates. Flexible, low-leakage, high temperature seals are required to seal the movable engine panels of advanced ramjet-scramjet engines either preventing potentially dangerous leakage into backside engine cavities or limiting the purge coolant flow rates through the seals. To predict the leakage through these flexible, porous seal structures as a function of preload and engine pressures, new analytical flow models are required. An empirical leakage resistance/preload model is proposed to characterize the observed decrease in leakage with increasing preload. Empirically determined compression modulus and preload factor are used to correlate experimental leakage data for a wide range of seal architectures. Good agreement between measured and predicted values are observed over a range of engine pressures and seal preloads.
Full-scale engine demonstration of an advanced sensor failure detection isolation, and accommodation algorithm - Preliminary results

The objective of the advanced detection, isolation, and accommodation (ADIA) program is to improve the overall demonstrated reliability of digital electronic control systems for turbine engines. For this purpose, algorithms were developed which detect, isolate, and accommodate sensor failures using analytical redundancy. Preliminary results of a full scale engine demonstration of the ADIA algorithm are presented. Minimum detectable levels of sensor failures for an F100 turbofan engine control system are determined and compared to those obtained during a previous evaluation of this algorithm using a real-time hybrid computer simulation of the engine.
Exploring the Behavior of Coherent Accelerator Processor Interface (CAPI) on IBM Power8+ Architecture and FlashSystem 900

The Coherent Accelerator Processor Interface (CAPI) is a general term for the infrastructure that provides high throughput and low latency path to the flash storage connected to the IBM POWER 8+ System. CAPI accelerator card is attached coherently as a peer to the Power8+ processor. This removes the overhead and complexity of the IO subsystem and allows the accelerator to operate as part of an application. In this paper, we present the results of experiments on IBM FlashSystem900 (FS900) with CAPI accelerator card using the “CAPIFlash - IBM Data Engine for NoSQL Software” Library. This library provides the application, a direct access to the underlying flash storage through user space APIs, to manage and access the data in flash. This offloads kernel IO driver functionality to dedicated CAPI FPGA accelerator hardware. We conducted experiments to analyze the performance of FS900 with CAPI accelerator card, using the Key Value Layer APIs, employing NASA’s MODIS Land Surface Reflectance dataset as a large dataset use case. We performed Read and Write operations on datasets of size ranging from 1MB to 3TB by varying the number of threads. We then compared this performance with other heterogeneous storage and memory devices such as NVM, SSD and RAM, without using the CAPI Accelerator in synchronous and asynchronous file IO modes of operations. The asynchronous mode had the best performance on all the memory devices that we used for this study. In particular, the results indicate that FS900 & CAPI, together with the metadata cache in RAM, delivers the highest IO/s and OP/s for read operations. This was higher than just using RAM, along with utilizing lesser CPU resources. Among FS900, SSD and NVM, FS900 had the highest write IO/s. Another important observation is that, when the size of the input dataset exceeds the capacity of RAM, and when the data access is non-uniform and sparse, FS900 with CAPI would be a cost-effective alternative.
Supersymmetric Elements in Divided Powers Algebras

Description of adjoint invariants of general linear Lie superalgebras $\mathfrak {gl}(m|n)$ by Kantor and Trishin was given in terms of supersymmetric polynomials. Later, generators of invariants of the adjoint action of the general linear supergroup GL(m|n) and generators of supersymmetric polynomials were determined over fields of positive characteristic. In this paper, we introduce the concept of supersymmetric elements in the divided powers algebra Div[x1,…, xm, y1,…, yn], and give a characterization of supersymmetric elements via a system of linear equations. Then we determine generators of supersymmetric elements for divided powers algebras in the cases when n = 0, n = 1, and m ≤ 2, n = 2.
Information Design in Spatial Resource Competition.

We consider the information design problem in spatial resource competition settings. Agents gather at a location deciding whether to move to another location for possibly higher level of resources, and the utility each agent gets by moving to the other location decreases as more agents move there. The agents do not observe the resource level at the other location while a principal does and the principal would like to carefully release this information to attract a proper number of agents to move. We adopt the Bayesian persuasion framework and analyze the principal's optimal signaling mechanism design problem. We study both private and public signaling mechanisms. For private signaling, we show the optimal mechanism can be computed in polynomial time with respect to the number of agents. Obtaining the optimal private mechanism involves two steps: first, solve a linear program to get the marginal probability each agent should be recommended to move; second, sample the moving agents satisfying the marginal probabilities with a sequential sampling procedure. For public signaling, we show the sender preferred equilibrium has a simple threshold structure and the optimal public mechanism with respect to the sender preferred equilibrium can be computed in polynomial time. We support our analytical results with numerical computations that show the optimal private and public signaling mechanisms achieve substantially higher social welfare compared with no information or full information benchmarks in many settings.
The C. elegans CHP1 homolog, pbo-1, functions in innate immunity by regulating the pH of the intestinal lumen

Caenorhabditis elegans are soil-dwelling nematodes and models for understanding innate immunity and infection. Previously, we developed a novel fluorescent dye (KR35) that accumulates in the intestine of C. elegans and reports a dynamic wave in intestinal pH associated with the defecation motor program. Here, we use KR35 to show that mutations in the Ca2+-binding protein, PBO-1, abrogate the pH wave, causing the anterior intestine to be constantly acidic. Surprisingly, pbo-1 mutants were also more susceptible to infection by several bacterial pathogens. We could suppress pathogen susceptibility in pbo-1 mutants by treating the animals with pH-buffering bicarbonate, suggesting the pathogen susceptibility is a function of the acidity of the intestinal pH. Furthermore, we use KR35 to show that upon infection by pathogens, the intestinal pH becomes neutral in a wild type, but less so in pbo-1 mutants. C. elegans is known to increase production of reactive oxygen species (ROS), such as H2O2, in response to pathogens, which is an important component of pathogen defense. We show that pbo-1 mutants exhibited decreased H2O2 in response to pathogens, which could also be partially restored in pbo-1 animals treated with bicarbonate. Ultimately, our results support a model whereby PBO-1 functions during infection to facilitate pH changes in the intestine that are protective to the host.
Implementation in Advised Strategies: Welfare Guarantees from Posted-Price Mechanisms when Demand Queries are NP-hard

State-of-the-art posted-price mechanisms for submodular bidders with $m$ items achieve approximation guarantees of $O((\log \log m)^3)$ [Assadi and Singla, 2019]. Their truthfulness, however, requires bidders to compute an NP-hard demand-query. Some computational complexity of this form is unavoidable, as it is NP-hard for truthful mechanisms to guarantee even an $m^{1/2-\varepsilon}$-approximation for any $\varepsilon > 0$ [Dobzinski and Vondrak, 2016]. Together, these establish a stark distinction between computationally-efficient and communication-efficient truthful mechanisms. We show that this distinction disappears with a mild relaxation of truthfulness, which we term implementation in advised strategies, and that has been previously studied in relation to "Implementation in Undominated Strategies" [Babaioff et al, 2009]. Specifically, advice maps a tentative strategy either to that same strategy itself, or one that dominates it. We say that a player follows advice as long as they never play actions which are dominated by advice. A poly-time mechanism guarantees an $\alpha$-approximation in implementation in advised strategies if there exists poly-time advice for each player such that an $\alpha$-approximation is achieved whenever all players follow advice. Using an appropriate bicriterion notion of approximate demand queries (which can be computed in poly-time), we establish that (a slight modification of) the [Assadi and Singla, 2019] mechanism achieves the same $O((\log \log m)^3)$-approximation in implementation in advised strategies.
Molecular evolution of the sex peptide network in Drosophila

Successful reproduction depends on interactions between numerous proteins beyond those involved directly in gamete fusion. Although such reproductive proteins evolve in response to sexual selection pressures, how networks of interacting proteins arise and evolve as reproductive phenotypes change remains an open question. Here, we investigated the molecular evolution of the 'sex peptide network' of Drosophila melanogaster, a functionally well-characterized reproductive protein network. In this species, the peptide hormone sex peptide (SP) and its interacting proteins cause major changes in female physiology and behaviour after mating. In contrast, females of more distantly related Drosophila species do not respond to SP. In spite of these phenotypic differences, we detected orthologs of all network proteins across 22 diverse Drosophila species and found evidence that most orthologs likely function in reproduction throughout the genus. Within SP-responsive species, we detected the recurrent, adaptive evolution of several network proteins, consistent with sexual selection acting to continually refine network function. We also found some evidence for adaptive evolution of several proteins along two specific phylogenetic lineages that correspond with increased expression of the SP receptor in female reproductive tracts or increased sperm length, respectively. Finally, we used gene expression profiling to examine the likely degree of functional conservation of the paralogs of an SP network protein that arose via gene duplication. Our results suggest a dynamic history for the SP network in which network members arose before the onset of robust SP-mediated responses and then were shaped by both purifying and positive selection.
Scan B-statistic for kernel change-point detection

Detecting the emergence of an abrupt change-point is a classic problem in statistics and machine learning. Kernel-based nonparametric statistics have been used for this task, which enjoys fewer ass...
Pitching Single-Focus Confocal Data Analysis One Photon at a Time with Bayesian Nonparametrics

Fluorescence time traces are used to report on dynamical properties of molecules. The basic unit of information in these traces is the arrival time of individual photons, which carry instantaneous information from the molecule, from which they are emitted, to the detector on timescales as fast as microseconds. Thus, it is theoretically possible to monitor molecular dynamics at such timescales from traces containing only a sufficient number of photon arrivals. In practice, however, traces are stochastic and in order to deduce dynamical information through traditional means-such as fluorescence correlation spectroscopy (FCS) and related techniques-they are collected and temporally autocorrelated over several minutes. So far, it has been impossible to analyze dynamical properties of molecules on timescales approaching data acquisition without collecting long traces under the strong assumption of stationarity of the process under observation or assumptions required for the analytic derivation of a correlation function. To avoid these assumptions, we would otherwise need to estimate the instantaneous number of molecules emitting photons and their positions within the confocal volume. As the number of molecules in a typical experiment is unknown, this problem demands that we abandon the conventional analysis paradigm. Here, we exploit Bayesian nonparametrics that allow us to obtain, in a principled fashion, estimates of the same quantities as FCS but from the direct analysis of traces of photon arrivals that are significantly smaller in size, or total duration, than those required by FCS.
Activity and characterization of Pd thin films, microfabricated dots, and cluster based model catalysts

The use of various model catalysts' configurations is illustrated to study the relation between catalytic activity and surface structure. The hydrogenation of 1,3‐butadiene is used as a test reaction to correlate kinetic parameters with catalysts' properties. The first model catalysts studied were Pd thin films. STM and XPS were used to characterize the catalyst and correlate the effect of sulfur poisoning with catalytic activity. It was found that the kinetic parameters depended on both the sulfur content and surface morphology. It is speculated that morphological changes caused by sulfur reconstruction change the distribution of active sites. The second model catalyst was a microfabricated catalyst consisting of a regular array of catalytic dots. Dots with different compositions were prepared to study the effect of Pd–Au alloys on activity. It was found that addition of gold decreased the activation energy and reduced the number of active sites by diluting the surface. The third type of model catalysts studied are catalysts derived from molecular clusters of clusters which have a well defined structure and composition. Upon pyrolysis, these materials decompose and form self‐supported porous bimetallic catalysts. It was found that the activity and selectivity of these materials varied with the structure of the precursor as well as with the temperature used to decompose them. These type of model catalysts provide a novel route to design new catalysts.
A comprehensive analysis of racial disparities in chemical biomarker concentrations in United States women, 1999-2014.

Abstract Background Stark racial disparities in disease incidence among American women remain a persistent public health challenge. These disparities likely result from complex interactions between genetic, social, lifestyle, and environmental risk factors. The influence of environmental risk factors, such as chemical exposure, however, may be substantial and is poorly understood. Objectives We quantitatively evaluated chemical-exposure disparities by race/ethnicity, life stage, and time in United States (US) women (n = 38,080) by using biomarker data for 143 chemicals from the National Health and Nutrition Examination Survey (NHANES) 1999–2014. Methods We applied a series of survey-weighted, generalized linear models using data from the entire NHANES women population along with cycle and age-group stratified subpopulations. The outcome was chemical biomarker concentration, and the main predictor was race/ethnicity with adjustment for age, socioeconomic status, smoking habits, and NHANES cycle. Results Compared to non-Hispanic White women, the highest disparities were observed for non-Hispanic Black, Mexican American, Other Hispanic, and Other Race/Multi-Racial women with higher levels of pesticides and their metabolites, including 2,5-dichlorophenol, o,p’-DDE, beta-hexachlorocyclohexane, and 2,4-dichlorophenol, along with personal care and consumer product compounds, including parabens and monoethyl phthalate, as well as several metals, such as mercury and arsenic. Moreover, for Mexican American, Other Hispanic, and non-Hispanic black women, there were several exposure disparities that persisted across age groups, such as higher 2,4- and 2,5-dichlorophenol concentrations. Exposure levels for methyl and propyl parabens, however, were the highest in non-Hispanic black compared to non-Hispanic white children with average differences exceeding 4-fold. Exposure disparities for methyl and propyl parabens are increasing over time in Other Race/Multi-Racial women while fluctuating for non-Hispanic Black, Mexican American, and Other Hispanic. Cotinine levels are among the highest in Non-Hispanic White women compared to Mexican American and Other Hispanic women with disparities plateauing and increasing, respectively. Discussion We systematically evaluated differences in chemical exposures across women of various race/ethnic groups and across age groups and time. Our findings could help inform chemical prioritization in designing epidemiological and toxicological studies. In addition, they could help guide public health interventions to reduce environmental and health disparities across populations.
Supreme Court 2018–2019: A New Justice, A “Capital” Term, and Some Light on the “Shadow Docket”

The 2018–2019 Supreme Court session included rulings on professional practice issues and social justice matters. No “blockbuster” decisions emerged. A large number of cases examined issues related to capital punishment, particularly around matters of competency. Challenges concerning jury selection and racial bias were addressed. Federal sex offender registration was upheld. Thirty-nine percent of cases were unanimous (down from the recent average), and 26% were decided by a 5-4 vote (up from the recent average).
A molecular rack and pinion actuates a cell-surface adhesin and enables bacterial gliding motility

The gliding bacterium Flavobacterium johnsoniae is known to have an adhesin, SprB, that moves along the cell surface on a spiral track. Following viscous shear, cells can be tethered by the addition of an anti-SprB antibody, causing spinning at 3 Hz. Labeling the type 9 secretion system (T9SS) with a YFP fusion of GldL showed a yellow fluorescent spot near the rotation axis, indicating that the motor driving the motion is associated with the T9SS. The distance between the rotation axis and the track (90 nm) was determined after adding a Cy3 label for SprB. A rotary motor spinning a pinion of radius 90 nm at 3 Hz would cause a spot on its periphery to move at 1.5 μm/s, the gliding speed. We suggest the pinion drives a flexible tread that carries SprB along a track fixed to the cell surface. Cells glide when this adhesin adheres to the solid substratum.
A Defect in Thymic Tolerance Causes T Cell-Mediated Autoimmunity in a Murine Model of COPA Syndrome.

COPA syndrome is a recently described Mendelian autoimmune disorder caused by missense mutations in the coatomer protein complex subunit α (COPA) gene. Patients with COPA syndrome develop arthritis and lung disease that presents as pulmonary hemorrhage or interstitial lung disease (ILD). Immunosuppressive medications can stabilize the disease, but many patients develop progressive pulmonary fibrosis, which requires life-saving measures, such as lung transplantation. Because very little is understood about the pathogenesis of COPA syndrome, it has been difficult to devise effective treatments for patients. To date, it remains unknown which cell types are critical for mediating the disease as well as the mechanisms that lead to autoimmunity. To explore these issues, we generated a CopaE241K/+ germline knock-in mouse bearing one of the same Copa missense mutations in patients. Mutant mice spontaneously developed ILD that mirrors lung pathology in patients, as well as elevations of activated cytokine-secreting T cells. In this study, we show that mutant Copa in epithelial cells of the thymus impairs the thymic selection of T cells and results in both an increase in autoreactive T cells and decrease in regulatory T cells in peripheral tissues. We demonstrate that T cells from CopaE241K/+ mice are pathogenic and cause ILD through adoptive transfer experiments. In conclusion, to our knowledge, we establish a new mouse model of COPA syndrome to identify a previously unknown function for Copa in thymocyte selection and demonstrate that a defect in central tolerance is a putative mechanism by which COPA mutations lead to autoimmunity in patients.
Image-based metric of invasiveness predicts response to adjuvant temozolomide for primary glioblastoma.

Background Temozolomide (TMZ) has been the standard-of-care chemotherapy for glioblastoma (GBM) patients for more than a decade. Despite this long time in use, significant questions remain regarding how best to optimize TMZ therapy for individual patients. Understanding the relationship between TMZ response and factors such as number of adjuvant TMZ cycles, patient age, patient sex, and image–based tumor features, might help predict which GBM patients would benefit most from TMZ, particularly for those whose tumors lack O6–methylguanine–DNA methyltransferase (MGMT) promoter methylation. Methods and findings Using a cohort of 90 newly–diagnosed GBM patients treated according to the standard of care, we examined the relationships between several patient and tumor characteristics and volumetric and survival outcomes during adjuvant chemotherapy. Volumetric changes in MR imaging abnormalities during adjuvant therapy were used to assess TMZ response. T1Gd volumetric response is associated with younger patient age, increased number of TMZ cycles, longer time to nadir volume, and decreased tumor invasiveness. Moreover, increased adjuvant TMZ cycles corresponded with improved volumetric response only among more nodular tumors, and this volumetric response was associated with improved survival outcomes. Finally, in a subcohort of patients with known MGMT methylation status, methylated tumors were more diffusely invasive than unmethylated tumors, suggesting the improved response in nodular tumors is not driven by a preponderance of MGMT methylated tumors. Conclusions Our finding that less diffusely invasive tumors are associated with greater volumetric response to TMZ suggests patients with these tumors may benefit from additional adjuvant TMZ cycles, even for those without MGMT methylation.
End-to-end Microphone Permutation and Number Invariant Multi-channel Speech Separation

An important problem in ad-hoc microphone speech separation is how to guarantee the robustness of a system with respect to the locations and numbers of microphones. The former requires the system to be invariant to different indexing of the microphones with the same locations, while the latter requires the system to be able to process inputs with varying dimensions. Conventional optimization-based beamforming techniques satisfy these requirements by definition, while for deep learning-based end-to-end systems those constraints are not fully addressed. In this paper, we propose transform-average-concatenate (TAC), a simple design paradigm for channel permutation and number invariant multi-channel speech separation. Based on the filter-and-sum network (FaSNet), a recently proposed end-to-end time-domain beamforming system, we show how TAC significantly improves the separation performance across various numbers of microphones in noisy reverberant separation tasks with ad-hoc arrays. Moreover, we show that TAC also significantly improves the separation performance with fixed geometry array configuration, further proving the effectiveness of the proposed paradigm in the general problem of multi-microphone speech separation.
Electrical resistivity in amorphous metals: Consequences of phonon ineffectiveness in the diffraction model

Abstract : Electrical transport in amorphous metals is analyzed in the context of the Baym-Faber-Ziman theory. The theory is generalized to incorporate electron mean free path effects through the Pippard-Ziman condition on the electron-phonon interaction. A variety of model t-matrices are considered. The geometrical structure factors are modeled by Percus-Yevick hard sphere forms and a single branch Debye phonon spectrum is assumed. Detailed results for electrical resistivity rho vs. temperature T and the TCR are presented for extensive ranges of 2kF/kp and electron mean free path. The results, incorporating the Pippard-Ziman condition, are consistent with the observed rho vs. T in low resistivity glassy metals. However, although inclusion of the Pippard-Ziman condition dramatically improves agreement with the data, quantitative agreement is not obtained in high resistivity amorphous metals.
Chapter 11 – Goodness of Fit Tests and Categorical Data Analysis

This chapter concerns with goodness of fit tests that can be used to test whether a proposed model is consistent with data. In it the classical chi–square goodness of fit test and apply it to test for independence in contingency tables is presented. The chapter also introduces the Kolmogorov–Smirnov procedure for testing whether data comes from a specified continuous probability distribution. The classical approach to obtaining a goodness of fit test of a null hypothesis that a sample has a specified probability distribution is to partition the possible values of the random variables into a finite number of regions. The situation where each member of a population is classified according to two distinct characteristics is also considered and it is shown how to use analysis to test the hypothesis that the characteristics of a randomly chosen member of the population are independent. The chapter also provides a practice exercise and solved examples.
Chapter 18 – Turtles

Anyone can identify a turtle based on the uniquely evolved carapace and plastron. In addition, all turtles share a unique cranial architecture including dentary bones that lack teeth but have keratinous sheaths as cutting edges. Turtles are comprised of 327 species distributed among 14 families. Their distribution is nearly global and includes widespread species that are marine. Turtles occur in swamps, rivers, streams, on land, and in the oceans. Conservation status of turtles is summarized. An up-to-date phylogeny details approximate time periods during which divergences occurred during the evolutionary history of turtles and shows evolutionary relationships among the families as we now know them. Taxonomic accounts provide information on generic content, distribution, characteristics, and biology of each family.
Standards for Psychotherapy

Standards of psychotherapy practice refer to what psychotherapists actually do, not to their education, credentials, or experience – although these factors might be precursors for practicing in a way that meets standard of ethics and efficacy. To understand these standards, it is ﬁrst necessary to know what has been established about the effectiveness of psychotherapy.
1988 Japanese Beef Market Access Agreement: Forecast Simulation Analysis

This paper uses dynamic simulation analysis to consider the likely consequences of the 1988 Japanese Beef Market Access Agreement (BMAA) on the Japanese livestock industry and beef imports. Using a simultaneous equations, econometric model of Japanese livestock markets, a forecast baseline up to 1997 was first established, asswning that the Japanese beef import quota continues to increase by 9,000 tons annually as under the 1984 agreement The restrictions of the new agreement were then imposed on the model. The results lead to a number of conclusions. Beef imports will increase to the new quota level in the first three years and continue increasing at about the same rate thereafter. The shift from the import quota to the import tariff in 1991 will have little effect on imports or prices. The US share of increasing Japanese beef imports will increase at the expense of Australia and New 7.ealand. The effects of the BMAA on the Japanese beef industry will be significant but less than devastating. The pigmeat industry will also be affected. The chicken and fish industries will be little affected. Finally, the degree of responsiveness of Japanese cattle prcxiucers to the expected beef price decline will significantly affect the outcome.
Public Finance and Transit-Oriented Planning: New Evidence from Southern California

Local governments seem to be continually strapped for funds. While the revenue-generating role of their planners is often discussed, it is rarely investigated in any detail. We address this researc...
Laboratory Simulations of Supernova Shockwave Propagation

Supernovae launch spherical shocks into the circumstellar medium (CSM). These shocks have high Mach numbers and may be radiative. We have created similar shocks in the laboratory by focusing laser pulses onto the tip of a solid pin surrounded by ambient gas; ablated material from the pin rapidly expands and launches a shock through the surrounding gas. Laser pulses were typically 5 ns in duration with ablative energies ranging from 1–150 J. Shocks in ambient gas pressures of ~1 kPa were observed at spatial scales of up to 5 cm using optical cameras with schlieren. Emission spectroscopy data were obtained to infer electron temperatures (< 10 eV). In this experiment we have observed a new phenomena; at the edge of the radiatively heated gas ahead of the shock, a second shock forms. The two expanding shocks are simultaneously visible for a time, until the original shock stalls from running into the heated gas. The second shock remains visible and continues to expand. A minimum condition for the formation of the second shock is that the original shock is super-critical, i.e., the temperature distribution ahead of the original shock has an inflexion point. In a non-radiative control experiment the second shock does not form. We hypothesize that a second shock could form in the astrophysical case, possibly in radiative supernova remnants such as SN1993J, or in shock-CSM interaction.
Web site metadata

The currently established formats for how a Web site can publish metadata about a site's pages, the robots.txt file and sitemaps, focus on how to provide information to crawlers about where to not go and where to go on a site. This is sufficient as input for crawlers, but does not allow Web sites to publish richer metadata about their site's structure, such as the navigational structure. This paper looks at the availability of Web site metadata on today's Web in terms of available information resources and quantitative aspects of their contents. Such an analysis of the available Web site metadata not only makes it easier to understand what data is available today; it also serves as the foundation for investigating what kind of information retrieval processes could be driven by that data, and what additional data could be provided by Web sites if they had richer data formats to publish metadata.
A Century of Purchasing-Power Parity

This paper investigates purchasing-power parity (PPP) since the late nineteenth century. I collected data for a group of twenty countries over 100 years, a larger historical panel of annual data than has ever been studied. The evidence for long-run PPP is favorable using recent multivariate and univariate tests of higher power. Residual variance analysis shows that episodes of floating exchange rates have generally been associated with larger deviations from PPP, as expected; this result is not attributable to significantly greater persistence (longer half-lives) of deviations in such regimes, but is due to the larger shocks to the real exchange rate process in such episodes. In the course of the twentieth century, there was relatively little change in the capacity of international market integration to smooth out real exchange rate shocks. Instead, changes in the size of shocks depended on the political economy of monetary and exchange rate regime choice under the constraints imposed by the trilemma.
Betting on the House: Subjective Expectations and Market Choices

Home price expectations play a central role in macroeconomics and finance. However, there is little direct evidence on how these expectations affect market choices. We provide the first experimental evidence based on a large-scale, high-stakes field experiment in the United States. We provided information by mail to 57,910 homeowners who recently listed their homes on the market. Collectively, these homes were worth $34 billion dollars. We randomized the information contained in the mailing to create non-deceptive, exogenous variation in the subjects’ home price expectations. We then used rich administrative data to measure the effects of these information shocks on the subject’s market choices. We find that, consistent with economic theory, higher home price expectations caused the subjects to delay selling their homes. These effects are statistically highly significant, economically large in magnitude, and robust to a number of sharp checks. Our results indicate that market choices are highly elastic to expectations: a 1 percentage point increase in home price expectations reduced the probability of selling within six months by 2.45 percentage points. Moreover, we provide evidence that this behavioral elasticity would be even higher if it were not for the presence of optimization frictions.
The Use of Group-Level Approaches to Environmental and Natural Resource Policy

AbstractPolicies to address environmental and natural resource management are often implemented at the group level. The defining feature of such policies is that penalties or rewards are based on g...
One reason countries pay their debts: renegotiation and international trade

Abstract I estimate the effect of sovereign debt renegotiation on international trade. Sovereigns may fear the trade consequences of default; because creditors deter default, or because trade finance dries up. I use an empirical gravity model of trade and a panel data set covering 50 years, over 150 countries, and other factors that influence bilateral trade. Debt renegotiation is associated with an economically and statistically significant decline in bilateral trade between a debtor and its creditors. The decline in bilateral trade is approximately 8% a year and persists for around 15 years.
Electrochemistry of Controlled-Diameter Carbon-Nanotube Fibers at the Cross Section and Sidewall

Electrochemistry at open ends and sidewalls of carbon nanotubes (CNTs) has been under debate, with opposing viewpoints as to which sites are more electrochemically active. A particular challenge in...
An Empirical Analysis of Imprisoning Drug Offenders

The number of prisoners incarcerated on drug-related offenses rose 15-fold between 1980 and 2000. This paper provides the first systematic empirical analysis of the implications of that dramatic shift in public policy. We estimate that cocaine prices are 5–15% higher today as a consequence of increases in drug punishment since 1985, presumably leading to reduced drug consumption. Incarcerating drug offenders is found to be almost as effective in reducing violent and property crime as locking up other types of offenders. Thus, although we demonstrate that the increase in drug prisoners led to reductions in expected time served for other crimes (especially for less serious offenses), the overall impact of increased drug incarceration has likely been a small (1–3%) reduction in violent and property crime. Back-of-the envelope estimates suggest that it is unlikely that the dramatic increase in drug imprisonment was cost-effective. D 2003 Elsevier B.V. All rights reserved.
Electronic control of the Bergman cycloaromatization: synthesis and chemistry of chloroenediynes.

A series of cyclic mono- and dichloroenediynes have been prepared using an intramolecular carbenoid coupling reaction. The halogen atom had a retardative effect on Bergman cycloaromatization in every case examined, and atom transfer chemistry was demonstrated, resulting in formation of adducts.
Long-term alterations in brain and behavior after postnatal Zika virus infection in infant macaques.

Zika virus (ZIKV) infection has a profound impact on the fetal nervous system. The postnatal period is also a time of rapid brain growth, and it is important to understand the potential neurobehavioral consequences of ZIKV infection during infancy. Here we show that postnatal ZIKV infection in a rhesus macaque model resulted in long-term behavioral, motor, and cognitive changes, including increased emotional reactivity, decreased social contact, loss of balance, and deficits in visual recognition memory at one year of age. Structural and functional MRI showed that ZIKV-infected infant rhesus macaques had persistent enlargement of lateral ventricles, smaller volumes and altered functional connectivity between brain areas important for socioemotional behavior, cognitive, and motor function (e.g. amygdala, hippocampus, cerebellum). Neuropathological changes corresponded with neuroimaging results and were consistent with the behavioral and memory deficits. Overall, this study demonstrates that postnatal ZIKV infection in this model may have long-lasting neurodevelopmental consequences. The consequences of postnatal Zika infection are not fully understood. Here, the authors show that postnatal Zika infection in infant rhesus macaques alters neurodevelopment resulting in social, cognitive and motor impairments, as well as structural and functional changes in the brain.
A Parallel Projection Method for Metric Constrained Optimization

Many clustering applications in machine learning and data mining rely on solving metric-constrained optimization problems. These problems are characterized by $O(n^3)$ constraints that enforce triangle inequalities on distance variables associated with $n$ objects in a large dataset. Despite its usefulness, metric-constrained optimization is challenging in practice due to the cubic number of constraints and the high-memory requirements of standard optimization software. Recent work has shown that iterative projection methods are able to solve metric-constrained optimization problems on a much larger scale than was previously possible, thanks to their comparatively low memory requirement. However, the major limitation of projection methods is their slow convergence rate. In this paper we present a parallel projection method for metric-constrained optimization which allows us to speed up the convergence rate in practice. The key to our approach is a new parallel execution schedule that allows us to perform projections at multiple metric constraints simultaneously without any conflicts or locking of variables. We illustrate the effectiveness of this execution schedule by implementing and testing a parallel projection method for solving the metric-constrained linear programming relaxation of correlation clustering. We show numerous experimental results on problems involving up to 2.9 trillion constraints.
A Realistic Argument for Scientific Realism: How to be a Realist Without Really Knowing It

In this paper I provide a novel argument for scientific realism (SR). In contrast to most recent defenses of SR, my defense of SR does not rely on the no-miracles argument (NMA). Instead, I take a more unconventional approach: I focus on the different kinds of justification available to different individuals in relation to different kinds of propositions. I maintain that this alternative focus shows that most people are warranted in believing many propositions about unobservables. The paper is divided into three main sections. In the first, I rehearse the main moves in the recent debate about SR. In the second, I argue that the discussion in section one enables us to see that most of the arguments in the recent debate about SR mistake their target: instead of being about SR, they are about meta-SR. I argue that what I call the JJ-principle should be rejected and, further, that if the JJ-principle is rejected, then meta-SR may be cleaved from SR. This enables me to advance to a position I call thin realism in the third and final section of the paper.
Unit commitment considering the impact of deep cycling

Abstract Wind energy has been integrated into power systems with the hope that it can improve energy efficiency and decrease greenhouse gas emissions. However, several studies from around the world have implied that this integration has had an opposite effect, mainly because of the negative correlation between wind availability and load. Under this dynamic situation, coal power plants are forced to cycle, which is not within their designed mode of operation. To prevent this unwanted result, a unit commitment decision should include the fuel usage and emission rates during the ramp up/down process. This paper proposes a new unit commitment decision process to accommodate the economic and environmental costs associated with the ramping process. These costs are generally not convex, because there is a positive cost if a generator output changes significantly (regardless of direction). As a result, the problem might be nonconvex. A piece-wise linear cost curve is introduced to model the impact of ramping processes. With this curve, convex linear programming is formulated and the impact of governmental policy is discussed.
A Conway–Maxwell-multinomial distribution for flexible modeling of clustered categorical data

Abstract Categorical data are often observed as counts resulting from a fixed number of trials in which each trial consists of making one selection from a prespecified set of categories. The multinomial distribution serves as a standard model for such data but assumes that trials are independent and identically distributed. Extensions such as the Dirichlet-multinomial and random-clumped multinomial distribution can express positive association, where trials are more likely to result in a common category due to membership in a common cluster. This work considers a Conway-Maxwell-multinomial (CMM) distribution for modeling clustered categorical data exhibiting positively or negatively associated trials. The CMM distribution features a dispersion parameter which allows it to adapt to a range of association levels and includes several recognizable distributions as special cases. We explore properties of CMM, illustrate its flexible characteristics, identify a method to efficiently compute maximum likelihood (ML) estimates, present simulations of small sample properties under ML estimation, and demonstrate the model via data analysis examples.
Decomposable polymatroids and connections with graph coloring

Abstract We introduce ideas that complement the many known connections between polymatroids and graph coloring. Given a hypergraph that satisfies certain conditions, we construct polymatroids, given as rank functions, that can be written as sums of rank functions of matroids, and for which the minimum number of matroids required in such sums is the chromatic number of the line graph of the hypergraph. This result motivates introducing chromatic numbers and chromatic polynomials for polymatroids. We show that the chromatic polynomial of any 2-polymatroid is a rational multiple of the chromatic polynomial of some graph. We also find the excluded minors for the minor-closed class of polymatroids that can be written as sums of rank functions of matroids that form a chain of quotients.
What is an explanation? Statistical physics and economics

There is a long history of statistical physics being looked to as a source of inspiration for the social sciences. There has been growing interest in the field. However, the bridge between the two has been imperfect. One way to understand why is that there are differences between their objects of explanation. While approaches derived from statistical physics may offer a useful tool in specific settings, it is vital to recognize when the insights that derive from them may be limited as a result of differences between the social and the physical world. We argue that methods from statistical physics can help in providing explanations of economic outcomes only if they include adequate attention to processes and moreover characterize these in an appropriate way, recognizing their specifically social character.
A theorem about maximal Cohen-Macaulay modules

It is shown in a local strongly $F$-regular ring there exits natural number $e_0$ so that if $M$ is any finitely generated maximal Cohen-Macaulay module then the pushforward of $M$ under the $e_0$th iterate of the Frobenius endomorphism contains a free summand. Consequently, the torsion subgroup of the divisor class group of a local strongly $F$-regular ring is finite.
Race, socioeconomic deprivation, and hospitalization for COVID-19 in English participants of a national biobank.

Preliminary reports suggest that the Coronavirus Disease 2019 (COVID− 19) pandemic has led to disproportionate morbidity and mortality among historically disadvantaged populations. We investigate the racial and socioeconomic associations of COVID− 19 hospitalization among 418,794 participants of the UK Biobank, of whom 549 (0.13%) had been hospitalized. Both Black participants (odds ratio 3.7; 95%CI 2.5–5.3) and Asian participants (odds ratio 2.2; 95%CI 1.5–3.2) were at substantially increased risk as compared to White participants. We further observed a striking gradient in COVID− 19 hospitalization rates according to the Townsend Deprivation Index − a composite measure of socioeconomic deprivation − and household income. Adjusting for socioeconomic factors and cardiorespiratory comorbidities led to only modest attenuation of the increased risk in Black participants, adjusted odds ratio 2.4 (95%CI 1.5–3.7). These observations confirm and extend earlier preliminary and lay press reports of higher morbidity in non-White individuals in the context of a large population of participants in a national biobank. The extent to which this increased risk relates to variation in pre-existing comorbidities, differences in testing or hospitalization patterns, or additional disparities in social determinants of health warrants further study.
Analysis and Performance Evaluation of Adjoint-guided Adaptive Mesh Refinement for Linear Hyperbolic PDEs Using Clawpack

Adaptive mesh refinement (AMR) is often used when solving time-dependent partial differential equations using numerical methods. It enables time-varying regions of much higher resolution, which can selectively refine areas to track discontinuities in the solution. The open source Clawpack software implements block-structured AMR to refine around propagating waves in the AMRClaw package. For problems where the solution must be computed over a large domain but is only of interest in a small area, this approach often refines waves that will not impact the target area. We seek a method that enables the identification and refinement of only the waves that will influence the target area. Here we show that solving the time-dependent adjoint equation and using a suitable inner product allows for a more precise refinement of the relevant waves. We present the adjoint methodology in general and give details on the implementation of this method in AMRClaw. Examples and a computational performance analysis for linear acoustics equations are presented. The adjoint method is compared to AMR methods already available in AMRClaw, and the advantages and disadvantages are discussed. The approach presented here is implemented in Clawpack, in Version 5.6.1, and code for all examples presented is archived on Github.