cssi/SciSciGPT-SciSciNet huggingface dataset:
XBiT: An XML-Based Bitemporal Data Model

Past research work on modeling and managing temporal information has, so far, failed to elicit support in commercial database systems. The increasing popularity of XML offers a unique opportunity to change this situation, inasmuch as XML and XQuery support temporal information much better than relational tables and SQL. This is the important conclusion claimed in this paper where we show that valid-time, transaction-time, and bitemporal databases can be naturally viewed in XML using temporally-grouped data models. Then, we show that complex historical queries, that would be very difficult to express in SQL on relational tables, can now be easily expressed in standard XQuery on such XML-based representations. We first discuss the management of transaction-time and valid-time histories and then extend our approach to bitemporal histories. The approach can be generalized naturally to support the temporal management of arbitrary XML documents and queries on their version history.
Cross‐Coupling Reactions of Organotrifluoroborate Salts

Organotrifluoroborates are partners for cross-coupling that have emerged as complementary and often unique alternatives to other organoboron reagents. This chapter provides a comprehensive overview of all cross-coupling reactions of the various classes of organotrifluoroborates that have been carried out through August, 2009. The chapter introduces the subject with a discussion of mechanistic considerations concerning the cross-coupling, followed by a brief discussion of the stereochemical aspects of the transformation. The scope and limitations of the reactions are subsequently discussed, first in terms of the organotrifluoroborate and then the electrophilic partner of the reaction. Potential side reactions that are encountered are outlined with useful suggestions on how these can be avoided in practice. Applications in synthesis are described, detailing how organotrifluoroborates have been utilized in the construction of natural products, materials of all types, and pharmacologically active substances. A comparison to other cross-coupling methods rounds out the descriptive part of the chapter. A detailed outline of experimental considerations and protocols has been assembled, gleaning information from the vast array of published procedures to assemble an overview of the most successful conditions. Representative procedures are included for each class of organotrifluoroborate coupling partner, and the tables provide a comprehensive listing of individual reactions. Keywords: organotrifluoroborates; Suzuki-Miyaura cross-coupling; palladium catalysis; nickel catalysis; ligands; biaryl synthesis
The chaotic attractor of foreign direct investment—Why China?: A panel data analysis

Abstract We explain that China is an “attractor” of FDI because its FDI inflows increased steadily even though the world FDI inflows have decreased considerably in recent years. It is indeed “strange” or “chaotic” since its rates of FDI return are below the world average and predictions of its economic crisis or collapse are abundant. We find that Hong Kong and Taiwan are predominant players (40–60% of total FDI), followed by the United States and EU, and the size of investment is generally very small. The concept of the China Circle should be expanded to the East Asia Circle, which is experienced by Taiwan and Korea in earlier decades. We also considered some important characteristics, including the regional distribution, geographic proximity, and cultural similarity of these countries. To avoid spurious regressions, we use panel unit root and cointegration tests developed in the last few years. The results from panel data regressions explain our observations quite satisfactorily.
Business start-ups and productive efficiency

This paper studies efficient allocation of resources in an economy in which agents are initially heterogeneous with regard to their wealth levels and whether they have ideas or not. An agent with an idea can start a business that generates random returns. Agents have private information about (1) their initial types, (2) how they allocate their resources, and (3) the realized returns. The unobservability of returns creates a novel motive for subsidizing agents who have ideas but lack resources to invest in them. To analyze this motive in isolation, the paper assumes that agents are risk-neutral and abstracts away from equality and insurance considerations. The unobservability of initial types and actions implies that the subsidy that poor agents with ideas receive is limited by incentive compatibility: the society should provide other agents with enough incentives so that they do not claim to be poor and have ideas. The paper then provides an implementation of the constrained-efficient allocation in an incomplete markets setup that is similar to the U.S. Small Business Administration's Business Loan Program. Finally, the paper extends the model in several dimensions to show that the results are robust to these generalizations of the model.
Orientalism and world history: Representing Middle Eastern nationalism and Islamism in the twentieth century

This is a essay about framing, about contextualization. It seeks to situate the political and cultural transitions the modern Middle East has undergone in this century in their world historical contexts, the better to help us understand the meanings of the present shift to Islamist forms of politics in the region. It is my contention that scholars have misunderstood the world historical significance of the emergence of nationalism in the area, that they have misconstrued its relationship to orientalism and to the European enlightenment more generally, and (as a result) largely misunderstood the nature of the Islamist challenge. In many ways my reflections here spring from a dissatisfaction with the inadequacies (both epistemological and world historical) of the ways in which some critics of orientalism have located modernity.
Spatial economic aspects of the environment and environmental policy: New directions for research

This paper outlines major new research directions for research on spatial or interregional effects of the environment and envrionmental policy. It attempts to define and characterize key research questions that lie at the intersection of environmental and resource economics and regional and urban economics. This intersection is of considerable importance because at least some factors of production are mobile, both domestically and worldwide. In consequence, information concerning the value of environmental attributes is revealed when people and firms relocate. Additionally, environmental policy changes can alter the interregional or international distributions of factor incomes, population, and production of goods and services.
Measuring Market Power in the U.S. Aluminum Industry: A Residual Demand Approach

This paper applies a refined market power test to examine market power in the U.S. aluminum industry. The study conducts a two-step analysis in which the inverse residual demand facing the industry is first estimated to generate the associate elasticity to infer market power, and then the inverse partial residual demand facing the industry is estimated to produce the elasticity to measure the potential effect of inter-industry coordination. The results suggest that only the primary industry attains market power, and the market power can exert even without collusion between the primary and secondary industries.
Convergence in Macroeconomics: Elements of the New Synthesis

While macroeconomics is often thought of as a deeply divided field, with less of a shared core and correspondingly less cumulative progress than in other areas of economics, in fact, there are fewer fundamental disagreements among macroeconomists now than in past decades. This is due to important progress in resolving seemingly intractable debates. In this paper, the author reviews some of those debates and outlines important elements of the new synthesis in macroeconomic theory. The author discusses the extent to which new developments in theory and research methods are already affecting macroeconomic analysis in policy institutions.
The Implicit Taxes from College Financial Aid

Abstract Families who earn more or who heed the “experts'” advice and save for college typically receive less financial aid. The financial aid system therefore implicitly taxes both income and assets. We use NPSAS aid award data to estimate these implicit taxes, and find that at average-priced colleges the marginal income tax ranges from 2 to 16% and the marginal asset levy from 8 to 26%. A typical family loses aid worth about $11 000 at average-priced colleges and $15 000 at expensive colleges by accumulating an extra $50 000 in assets.
Concluding remarks from the Artificial Intelligence perspective

This summary reviews some recurrent themes of the conference. We have a few suggestions about how funding might help us now. Finally, we want to pass along a suggestion that might improve the next conference.
Service Export sophistication and Europe's new growth model

Technology has changed the nature of service activities and made them more productive, tradable and fragmented in the global supply chain. Has Europe's growth been benefiting from the ongoing globalization of services? Services dominate growth in EU-15 countries and, to a lesser extent, in New Member States (NMS) and Accession (ACC) countries. Except in the ACC region, Europe has maintained specialization in service exports. Service productivity, tradability, and exports of modern services are high in EU-15, growing fast in NMS while at a lower pace in ACC. Service export sophistication is important for growth across the region, but especially in NMS.
Coadjoint orbits, moment polytopes, and the Hilbert-Mumford criterion

Consider a compact Lie group and a closed subgroup. Generalizing a result of Klyachko, we give a necessary and sufficient criterion for a coadjoint orbit of the subgroup to be contained in the projection of a given coadjoint orbit of the ambient group. The criterion is couched in terms of the ``relative'' Schubert calculus of the flag varieties of the two groups.
Improved Spectral-Norm Bounds for Clustering

Aiming to unify known results about clustering mixtures of distributions under separation conditions, Kumar and Kannan [1] introduced a deterministic condition for clustering datasets. They showed that this single deterministic condition encompasses many previously studied clustering assumptions. More specifically, their proximity condition requires that in the target k-clustering, the projection of a point x onto the line joining its cluster center μ and some other center μ′, is a large additive factor closer to μ than to μ′. This additive factor can be roughly described as k times the spectral norm of the matrix representing the differences between the given (known) dataset and the means of the (unknown) target clustering. Clearly, the proximity condition implies center separation – the distance between any two centers must be as large as the above mentioned bound.
Range Image Segmentation and Classification via Split-and-Merge Based on Surface Curvature

Surface curvatures have been widely used for the purpose of segmenting and classifying range images. However, since surface curvatures include the second order derivatives, they become unreliable in the presence of noise, yielding false segmentation and/or classification of the range images. In this paper we investigate the sensitivity of the surface curvatures to the noise, and provide some observations on the characteristics of surface curvatures in the presence of noise. Following these observations, we then propose a scheme for reliable range image segmentation and classification. This scheme first differentiate planar region from curved region using planarity test. Surface curvatures are then computed only from the points belonging to the curved region, and mean curvature sign image (MCSI) and Gaussian curvature sign image (GCSI) are generated. Segmentation is done using split-and-merge operations on a quadtree representation of the MCSI. The sign of the Gaussian curvature is incorporated with the segmented MCSI to give a classification of the region. In the preliminary classification stage, the distribution of the Gaussian curvature signs are considered for each segmented region of the segmented MCSI. In the secondary classification stage, unclassified regions from the preliminary classification are classified using split-and-merge operations based on predominant Gaussian curvature signs.
A multivariate discretization method for learning Bayesian networks from mixed data

In this paper we address the problem of discretization in the context of learning Bayesian networks (BNs) from data containing both continuous and discrete variables. We describe a new technique for multivariate discretization, whereby each continuous variable is discretized while taking into account its interaction with the other variables. The technique is based on the use of a Bayesian scoring metric that scores the discretization policy for a continuous variable given a BN structure and the observed data. Since the metric is relative to the BN structure currently being evaluated, the discretization of a variable needs to be dynamically adjusted as the BN structure changes.
Parallel operation of voltage source inverters with minimal intermodule reactors

Realization of large horsepower motor drives using parallel-connected voltage source inverters rated at smaller power levels would be highly desirable. A robust technique for such a realization would result in several benefits including modularity, ease of maintenance, n+1 redundancy, reliability, etc. Techniques for parallel operation of voltage source inverters with relatively large load inductance have been well established in the field of UPS systems. This paper presents an approach to such realization using minimal passive components along with an active current balancing strategy for motor drive systems. Analytical models, computer simulations and experimental results are presented.
Very high-speed digital subscriber lines (VDSL)

Very high-speed digital subscriber lines (VDSL) are overviewed with an emphasis on the basic architecture, applications, and data rates, as well as the technological challenges of the design. Discussions of the telephone line environment, radio-band interference ingress and egress, impulse noise, and symmetric and asymmetric multiplexing are included along with the consequent description of a popular implementation.
The long run health returns to college quality

The link between education and health is one of the most robust empirical relationships in the social sciences. However, little research has examined the effects of educational quality on health outcomes. We estimate the long run relationship between health behaviors and graduating from a selective college in the 1960s using the Wisconsin Longitudinal Study, which has tracked siblings for over 50 years. Importantly, we control for measures of health endowments, ability, and time preferences before college enrollment as well as shared family and environmental factors. We find large effects of college selectivity on reducing overweight for individuals in their 60s.
Stable Solutions for Dynamic Constraint Satisfaction Problems

An important extension of constraint technology involves problems that undergo changes that may invalidate the current solution. Previous work on dynamic problems sought methods for efficiently finding new solutions. We take a more proactive approach, exploring methods for finding solutions more likely to remain valid after changes that temporarily alter the set of valid assignments (stable solutions). To this end, we examine strategies for tracking changes in a problem and incorporating this information to guide search to solutions that are more likely to be stable. In this work search is carried out with a min-conflicts hill climbing procedure, and information about change is used to bias value selection, either by distorting the objective function or by imposing further criteria on selection. We study methods that track either value losses or constraint additions, and incorporate information about relative frequency of change into search. Our experiments show that these methods are generally effective in finding stable solutions, and in some cases handle the tradeoff between solution stability and search efficiency quite well. In addition, we identify one condition in which these methods markedly reduce the effort to find a stable solution.
On the Long Run Effects of Public Capital and Disaggregated Public Capital on Aggregate Output

We study the cointegration properties of data on aggregate output, five proxies for labor, two proxies for private capital, public capital, and disaggregated public capital for the United States for 1948–1993. We find evidence of multiple cointegrating vectors; we typically find three or four cointegrating vectors depending on which combination of proxies is evaluated. When public capital is disaggregated by type there is less evidence for cointegration. Finally, innovations in public capital have long lasting effects on output, labor, and private capital, and innovations to output, labor, and private capital also have long lasting effects on public capital.
Multiplexed protein quantification with barcoded hydrogel microparticles.

We demonstrate the use of graphically encoded hydrogel microparticles for the sensitive and high-throughput multiplexed detection of clinically relevant protein panels in complex media. Combining established antibody capture techniques with advances in both microfluidic synthesis and analysis, we detected 1−8 pg/mL amounts of three cytokines (interleuken-2, interleuken-4, and tumor necrosis factor alpha) in single and multiplexed assays without the need for filtration or blocking agents. A range of hydrogel porosities was investigated to ensure rapid diffusion of targets and reagents into the particle as well as to maintain the structural integrity of particles during rinsing procedures and high-velocity microfluidic scanning. Covalent incorporation of capture antibodies using a heterobifunctional poly(ethylene glycol) linker enabled one-step synthesis and functionalization of particles using only small amounts of valuable reagents. In addition to the use of three separate types of single-probe particles,...
Gender Differences in Time-Poverty in Rural Mozambique

Based on time-use data from a 2013 primary household survey, this study examines the nature and extent of time-poverty experienced by men and women in peasant households in Mozambique. The main findings indicate that while women's labor allocation to economic activities is comparable to that of men, household chores and care work are almost entirely women's responsibility. The heavy burden of responsibilities leave women significantly time-poorer compared to men. Women's time-poverty worsens when the burden of simultaneous care work is taken into account. In addition, due to multitasking, the work tends to be more taxing. The examination of determinants of time-poverty shows that common measures of individual economic power, such as assets and education, do not necessarily affect the time-poverty faced by women.
Chest modeling and personalized surgical planning for pectus excavatum.

Pectus excavatum is among the most common major congenital anomalies of the chest wall whose correction can be performed via minimally invasive Nuss technique that places a pectus bar to elevate the sternum anteriorly. However, the size and bending of the pectus bar are manually modeled intra-operatively by trial-and-error. The procedure requires intense pain management in the months following surgery. In response, we are developing a novel distraction device for incremental and personalized PE correction with minimal risk and pain, akin to orthodontic treatment using dental braces. To design the device, we propose in this study a personalized surgical planning framework for PE correction from clinical noncontrast CT. First, we segment the ribs and sternum via kernel graph cuts. Then costal cartilages, which have very low contrast in noncontrast CT, are modeled as 3D anatomical curves using the cosine series representation and estimated using a statistical shape model. The size and shape of the correction device are estimated through model fitting. Finally, the corrected/post-surgical chest is simulated in relation to the estimated shape of correction device. The root mean square mesh distance between the estimated cartilages and ground truth on 30 noncontrast CT scans was 1.28±0.81 mm. Our method found that the average deformation of the sterna and cartilages with the simulation of PE correction was 49.71±10.11 mm.
Former Communist Countries and their transition to Capitalism

This paper uses the technology adoption general equilibrium model developed by Moscoso Boedo (2006) to analyze the transition for the countries of the former USSR and Eastern Europe. There the real output displayed a U-shapped pattern together with increases in inequality, which are features matched by the model
Quantum Theory in Accelerated Frames of Reference

The observational basis of quantum theory in accelerated systems is stud- ied. The extension of Lorentz invariance to accelerated systems via the hypothesis of locality is discussed and the limitations of this hypothesis are pointed out. The non- local theory of accelerated observers is briefly described. Moreover, the main observa- tional aspects of Dirac's equation in noninertial frames of reference are presented. The Galilean invariance of nonrelativistic quantum mechanics and the mass superselection rule are examined in the light of the invariance of physical laws under inhomogeneous Lorentz transformations.
The Impact of CO2 Emission Cuts on Income

We study how carbon dioxide (CO2) emission cuts affect income for 23 OECD countries over the 1980-2004 period. The importance of this question is manifested in the disagreements at the 2009 United Nations Climate Change Conference in Copenhagen and the 2010 State of the Union Address by United States President Barack Obama. We start by deriving an income-CO2 relationship based on a structural production function, which is a natural way to model the relationship among income, energy consumption, and CO2 emissions. We then use a similar empirical methodology as Tucker (1995) to estimate the income-CO2 relationship. Such an approach not only allows us to focus on the long-run relationship but also enables us to project the relationship between income and CO2 emissions for future years. Our findings suggest that the economic cost of CO2 emission cuts is significant. To reduce emissions 50% below 1990 levels by 2050, the economic cost per year for developed countries is about 0.3% reduction in GDP per capita which represents a 15% slowdown in economic growth.
Random graphs as models of networks

The random graph of Erdos and Renyi is one of the oldest and best studied models of a network, and possesses the considerable advantage of being exactly solvable for many of its average properties. However, as a model of real-world networks such as the Internet, social networks or biological networks it leaves a lot to be desired. In particular, it differs from real networks in two crucial ways: it lacks network clustering or transitivity, and it has an unrealistic Poissonian degree distribution. In this paper we review some recent work on generalizations of the random graph aimed at correcting these shortcomings. We describe generalized random graph models of both directed and undirected networks that incorporate arbitrary non-Poisson degree distributions, and extensions of these models that incorporate clustering too. We also describe two recent applications of random graph models to the problems of network robustness and of epidemics spreading on contact networks.
A Neoclassical Growth Model with Endogenous Retirement

This paper extends Diamond (1965)’s one-sector neoclassical growth model with twoperiod lived, overlapping generations, by allowing the agents to make the labor force participation decision in their second period, in the spirit of Feldstein (1974). If the agents earn a high wage income when young, they choose to retire when old. This reduces the labor supply (through a lower participation rate of the elderly) and stimulates capital accumulation (through saving for retirement). The resulting high capital-labor ratio leads to a higher wage income for the next generation. If the agents earn a low wage income when young, they continue to work when old and save little, which implies a low capital-labor ratio and a low wage income for the next generation. Due to such positive feedback mechanisms, the endogeneity of retirement magnifies the persistence of growth dynamics, thereby slowing down a convergence to the steady state, and even generating multiple steady states for empirically plausible parameter values.
Seeking the Ultraviolet Ionizing Background at z ≈ 3 with the Keck Telescope

We describe the initial results of a deep long-slit emission-line search for redshifted (2.7 < z < 4.1) Lyα. These observations are used to constrain the fluorescent Lyα emission from the population of clouds whose absorption produces the higher column density component of the Lyα forest in quasar spectra. We use the results to set an upper limit on the ultraviolet ionizing background. Our spectroscopic data obtained with the Keck II Telescope at λ/ΔλFWHM ≈ 2000 reveal no candidate Lyα emission over the wavelength range of 4500–6200 A along a 3' slit in a 5400 s integration. This null result places the strongest limit to date on the ambient flux of Lyman continuum photons at z ≈ 3. Typically, we attain a 1 σ surface brightness sensitivity to spectrally unresolved line emission in a 1 arcsec2 aperture of (0.4–0.6) × 10-18 ergs s-1 cm-2 arcsec-2, and we search for extended emission over a wide range of spatial scales. Our 3 σ upper bound on the mean intensity of the ionizing background at the Lyman limit is Jν0 < 2 × 10-21 ergs s-1 cm-2 Hz-1 sr-1 for 2.7 < z < 3.1 (where we are most sensitive), assuming that Lyman limit systems have typical radii of 70 kpc (q0 = 0.5, H0 = 50 km s-1 Mpc-1). This constraint is more than an order of magnitude more stringent than any previously published direct limit. However, it is still a factor of 3 above the ultraviolet background level expected due to the integrated light of known quasars at z ≈ 3. This pilot study confirms the conclusion of Gould &Weinberg that integrations of several hours on a 10 m–class telescope should be capable of measuring Jν0 at high redshift. Our results suggest that the integrated flux of Lyman continuum photons escaping from star-forming galaxies at these epochs cannot exceed twice that from known quasars. We also show that it is unlikely that decaying relic neutrinos, if composing the bulk of the dark matter, are responsible for the metagalactic radiation field.
D (+jets) in Deep Inelastic Scattering and Photoproduction

New results on charm quark production at HERA in an increased phase space in deep-inelastic scattering and photoproduction are discussed. Single & double-differential cross section distributions are compared to next-to-leading order QCD calculations as well as to MC@NLO in the photoproduction regime. The charm contribution to the proton structure, F_2^cc(x,Q^2), is determined with different experimental techniques and finally combined.
The Performance of Two Phase Commit Protocols in the Presence of Site Failures

The two phase commit is an important protocol in distributed database systems. Much of the existing literature on the protocol is restricted to discussing and analyzing the protocol (and its variants) in the absence of failures. Very little, especially in quantitative terms, has been written about its performance in the presence of site failures. In this study, we use a simulation testbed of a distributed database system to quantify the differences in the performances of four widely known variants of the 2PC protocols (the generic 2PC, presumed commit, presumed abort, and early prepare). Our study covers both the no-failure case and the case of site failures. We present a number of interesting results based on our experiments. One is that the performance of these protocols is highly dependent on the message-processing latency at the transaction coordinator site. Another is that the presumed abort protocol does not necessarily yield better performance in the presence of site failures.
Research Priorities in Geriatric Palliative Care: Policy Initiatives

Abstract Coordinated palliative care matched to patient needs improves quality of care for vulnerable patients with serious illness and reduces costly use of hospitals and emergency departments. Unfortunately, there is a disconnect in translating geriatric palliative care models and principles into policy and widespread practice. Gaps in policy-relevant research are addressed, including implementation strategies to scale up existing care models, the role of palliative care and geriatrics in health care payment reform efforts, development of quality measures for complex patients, strategies to address workforce shortages, and an approach to hospice reform.
The two-hour orbit of a binary millisecond X-ray pulsar

Typical radio pulsars are magnetized neutron stars that are born rapidly rotating and slow down as they age on time scales of 10 to 100 million years. In contrast, millisecond radio pulsars spin very rapidly even though many are billions of years old1. The most compelling explanation is that they have been ‘spun up’ by the transfer of angular momentum during the accretion of material from a companion star in so-called low-mass X-ray binary systems, LMXBs. (LMXBs consist of a neutron star or black hole accreting matter from a companion with mass less than one solar mass2.) The recent detection of coherent X-ray pulsations with a millisecond period from a suspected low-mass X-ray binary system appears to confirm this link3. Here we report observations showing that the orbital period of this binary system is two hours, which establishes it as an LMXB. We also find an apparent modulation of the X-ray flux at the orbital period (at the two per cent level), with a broad minimum when the pulsar is behind the low-mass companion star. This system seems closely related to the ‘black-widow’ millisecond radio pulsars, which are evaporating their companions through irradiation4,5,6,7,8. It may appear as an eclipsing radio pulsar during periods of X-ray quiescence.
Thermal control system for Space Station Freedom photovoltaic power module

The electric power for Space Station Freedom (SSF) is generated by the solar arrays of the photovoltaic power modules (PVM's) and conditioned, controlled, and distributed by a power management and distribution system. The PVM's are located outboard of the alpha gimbals of SSF. A single-phase thermal control system is being developed to provide thermal control of PVM electrical equipment and energy storage batteries. This system uses ammonia as the coolant and a direct-flow deployable radiator. This paper presents the description and development status of the PVM thermal control system.
Stimulated and spontaneous relaxation in glassy systems

Recent numerical simulations of a disordered system have shown the existence of two different relaxational processes characterizing the relaxation observed in structural glasses. The existence of these two processes has been claimed to be at the roots of the intermittency phenomenon observed in recent experiments. It is considered that a generic system is put in contact with a bath at temperature T and characterized by an adiabatic slow relaxation in the aging state. The chapter focuses on a simplified scenario characterized by the fact that T = 0 and whose microscopic stochastic dynamics is ergodic when constrained to the constant energy surface. Three different effective temperatures can be defined—from the fluctuation–dissipation theorem (FDT), from a fluctuation theorem describing the statistical distribution of heat exchange events between system and bath, and from a set of observable-dependent microcanonical relations in the aging state. In a partial equilibration scenario, all three temperatures coincide reinforcing, the idea that a statistical definition of a non-equilibrium temperature is physically meaningful in aging systems. These results are explicitly checked in a simple model system.
Analysis of a Population Genetics Model with Mutation, Selection, and Pleiotropy

We investigate a population genetics model introduced by Waxman and Peck(1) incorporating mutation, selection, and pleiotropy (one gene affecting several unrelated traits). The population is infinite, and continuous variation of genotype is allowed. Nonetheless, Waxman and Peck showed that if each gene affects three or more traits, then the steady-state solution of the model can have a nonzero fraction of the population with identical alleles. We use a recursion technique to calculate the distribution of alleles at finite times as well as in the infinite-time limit. We map Waxman and Peck's model into the mean-field theory for Bose condensation, and a variant of the model onto a bound-state problem in quantum theory. These mappings aid in delineating the region of parameter space in which the unique genotype occurs. We also discuss our attempts to correlate the statistics of DNA-sequence variation with the degree of pleiotropy of various genes.
Continued Fractions and Unique Additive Partitions

A partition of the positive integers into sets A and B avoids a set S ⊂ N if no two distinct elements in the same part have a sum in S. If the partition is unique, S is uniquely avoidable. For any irrational α > 1, Chow and Long constructed a partition which avoids the numerators of all convergents of the continued fraction for α, and conjectured that the set Sα which this partition avoids is uniquely avoidable. We prove that the set of numerators of convergents is uniquely avoidable if and only if the continued fraction for α has infinitely many partial quotients equal to 1. We also construct the set Sα and show that it is always uniquely avoidable.
Neural network spectral robustness under perturbations of the underlying graph

Recent studies have been using graph-theoretical approaches to model complex networks such as social, infrastructural, or biological networks and how their hardwired circuitry relates to their dynamic evolution in time. Understanding how configuration reflects on the coupled behavior in a system of dynamic nodes can be of great importance, for example, in the context of how the brain connectome is affecting brain function. However, the effect of connectivity patterns on network dynamics is far from being fully understood. We study the connections between edge configuration and dynamics in a simple oriented network composed of two interconnected cliques representative of brain feedback regulatory circuitry. In this article our main goal is to study the spectra of the graph adjacency and Laplacian matrices, with a focus on three aspects in particular: 1i¾ the sensitivity and robustness of the spectrum in response to varying the intra-and intermodular edge density, 2 the effects on the spectrum of perturbing the edge configuration while keeping the densities fixed, and 3 the effects of increasing the network size. We study some tractable aspects analytically, then simulate more general results numerically, thus aiming to motivate and explain our further work on the effect of these patterns on the network temporal dynamics and phase transitions. We discuss the implications of such results to modeling brain connectomics. We suggest potential applications to understanding synaptic restructuring in learning networks and the effects of network configuration on function of regulatory neural circuits.
Compressibility of an ultracold Fermi gas with repulsive interactions

Fermi gases with repulsive interactions are characterized by measuring their compressibility as a function of interaction strength. The compressibility is obtained from in-trap density distributions monitored by phase-contrast imaging. For interaction parameters ${k}_{F}ag0.25$, fast decay of the gas prevents the observation of equilibrium profiles. For smaller interaction parameters, the results are adequately described by first-order perturbation theory. We have developed a phase-contrast imaging method that compensates for dispersive distortions of the images.
Iridium-Catalyzed Allylic Substitution

Iridium-catalyzed asymmetric allylic substitution has become a valuable method to prepare products from the addition of nucleophiles at the more substi- tuted carbon of an allyl unit. The most active and selective catalysts contain a phosphoramidite ligand possessing at least one arylethyl substituent on the nitrogen atom of the ligand. In these systems, the active catalyst is generated by a base- induced cyclometalation at the methyl group of this substituent to generate an iridium metalacycle bound by the COD ligand of the (Ir(COD)Cl)2 precursor and one additional labile dative ligand. Such complexes catalyze the reactions of linear allylic esters with alkylamines, arylamines, phenols, alcohols, imides, carbamates, ammonia, enolates and enolate equivalents, as well as typical stabilized carbon nucleophiles generated from malonates and cyanoesters. Iridium catalysts for enantioselective allylic substitution have also been generated from phosphorus ligands with substituents bound by heteroatoms, and an account of the studies of such systems, along with a description of the development of iridium catalysts is included.
Lunar transit telescope lander design

The Program Development group at NASA's Marshall Space Flight Center has been involved in studying the feasibility of placing a 16 meter telescope on the lunar surface to scan the skies using visible/ Ultraviolet/ Infrared light frequencies. The precursor telescope is now called the TRANSIT LUNAR TELESCOPE (LTT). The Program Development Group at Marshall Space Flight Center has been given the task of developing the basic concepts and providing a feasibility study on building such a telescope. The telescope should be simple with minimum weight and volume to fit into one of the available launch vehicles. The preliminary launch date is set for 2005. A study was done to determine the launch vehicle to be used to deliver the telescope to the lunar surface. The TITAN IV/Centaur system was chosen. The engineering challenge was to design the largest possible telescope to fit into the TITAN IV/Centaur launch system. The telescope will be comprised of the primary, secondary and tertiary mirrors and their supporting system in addition to the lander that will land the telescope on the lunar surface and will also serve as the telescope's base. The lunar lander should be designed integrally with the telescope in order to minimize its weight, thus allowing more weight for the telescope and its support components. The objective of this study were to design a lander that meets all the constraints of the launching system. The basic constraints of the TITAN IV/Centaur system are given.
Neural activation during risky decision-making in youth at high risk for substance use disorders.

Risky decision-making, particularly in the context of reward-seeking behavior, is strongly associated with the presence of substance use disorders (SUDs). However, there has been little research on the neural substrates underlying reward-related decision-making in drug-naive youth who are at elevated risk for SUDs. Participants comprised 23 high-risk (HR) youth with a well-established SUD risk phenotype and 27 low-risk healthy comparison (HC) youth, aged 10-14. Participants completed the balloon analog risk task (BART), a task designed to examine risky decision-making, during functional magnetic resonance imaging. The HR group had faster reaction times, but otherwise showed no behavioral differences from the HC group. HR youth experienced greater activation when processing outcome, as the chances of balloon explosion increased, relative to HC youth, in ventromedial prefrontal cortex (vmPFC). As explosion probability increased, group-by-condition interactions in the ventral striatum/anterior cingulate and the anterior insula showed increasing activation in HR youth, specifically on trials when explosions occurred. Thus, atypical activation increased with increasing risk of negative outcome (i.e., balloon explosion) in a cortico-striatal network in the HR group. These findings identify candidate neurobiological markers of addiction risk in youth at high familial and phenotypic risk for SUDs.
Basement membrane in the uterine cervix

Abstract A basement membrane could not be demonstrated with any degree of consistency in specimens of human cervix by means of the Ritter-Oleson staining technique, even though this technique demonstrated the membrane satisfactorily in control sections of normal breast and kidney tissue. The use of the term “basement membrane” and associated phrases such as “extension through” and “disruption of” in describing criteria for diagnosing invasive uterine cervical carcinoma is ill-advised. From our study, the existence of a basement membrane in the human cervix is more apparent than real. The criteria for distinguishing in situ from invasive carcinoma in the cervix should be the same as those used for such a distinction in any other organ. The Ritter-Oleson stain seems to have no practical value in facilitating this differentiation.
Workers' age and the impact of trade shocks

Do trade shocks affect workers differently because of their age? This paper examines the issue by estimating the lifetime mobility of workers based on the sectors in which they work. Using U.S. data, the paper shows that mobility costs rise with a worker's age and years of experience, but stay the same regardless of his or her education level. In addition, using a general-equilibrium simulation of counterfactual trade-liberalization policies in the metal manufacturing sector, the paper shows that trade shocks affect workers with higher mobility costs more, for both winners and losers of the policy shocks. But the effects taper off over a worker's lifetime, especially when they are close to retirement.
Trading Classical and Quantum Computational Resources

Hybrid quantum-classical computation may be a hallmark of future technologies. Researchers investigate the tradeoff between employing quantum and classical resources for computational tasks.
The relationship between siblings’ college choices: Evidence from one million SAT-taking families ☆

Abstract Recent empirical work has demonstrated the importance both of educational peer effects and of various factors that affect college choices. We connect these literatures by highlighting a previously unstudied determinant of college choice, namely the college choice made by one's older sibling. Data on 1.6 million sibling pairs of SAT-takers reveals that younger and older siblings’ choices are very closely related. One-fifth of younger siblings enroll in the same college as their older siblings. Compared to their high school classmates of similar academic skill and with observably similar families, younger siblings are about 15–20 percentage points more likely to enroll in 4-year colleges or highly competitive colleges if their older siblings do so first. These findings vary little by family characteristics. Younger siblings are more likely to follow the college choices of their older siblings the more they resemble each other in terms of academic skill, age and gender. We discuss channels through which older siblings’ college choices might causally influence their younger siblings, noting that the facts documented here should prompt further research on the sharing of information and shaping of educational preferences within families.
Can a Summer Make a Difference? The Impact of the American Economic Association Summer Program on Minority Student Outcomes

Abstract In the 1970s, the American Economic Association (AEA) was one of several professional associations to launch a summer program with the goal of increasing racial and ethnic diversity in its profession. In this paper we estimate the effectiveness of the AEA's program which, to the best of our knowledge, is the first to rigorously study such a summer program. Using a comparison group consisting of those who applied to, but did not attend, the program and controlling for an array of background characteristics, we find that program participants were over 40 percentage points more likely to apply to and attend a Ph.D. program in economics, 26 percentage points more likely to complete a Ph.D., and about 15 percentage points more likely to ever work in an economics-related academic job. Using our estimates, we calculate that the program may directly account for 17–21 percent of the Ph.D.s awarded to minorities in economics over the past 20 years.
MR Signal Abnormalities at 1.5 T in Alzheimer's Dementia and Normal Aging

The type, frequency, and extent of MR signal abnormalities in Alzheimer9s disease and normal aging are a subject of controversy. With a 1.5-MR unit we studied 12 Alzheimer patients, four subjects suffering from multiinfarct dementia and nine age-matched controls. Punctate or early confluent high-signal abnormalities in the deep white matter, noted in 60% of both Alzheimer patients and controls, were unrelated to the presence of hypertension or other vascular risk factors. A significant number of Alzheimer patients exhibited a more extensive smooth “halo” of periventricular hyperintensity when compared with controls (p = .024). Widespread deep white-matter hyperintensity (two patients) and extensive, irregular periventricular hyperintensity (three patients) were seen in multiinfarct dementia. Areas of high signal intensity affecting hippocampal and sylvian cortex were also present in five Alzheimer and two multiinfarct dementia patients, but absent in controls. Discrete, small foci of deep white-matter hyperintensity are not characteristic of Alzheimer9s disease nor do they appear to imply a vascular cause for the dementing illness. The frequently observed “halo” of periventricular hyperintensity in Alzheimer9s disease may be of diagnostic importance. High-signal abnormalities in specific cortjcal regions are likely to reflect disease processes localized to those structures.
On the interpretation of the apparent existence of a preferred magnetic polarity in extragalactic jet sources

Contopoulos et al. recently argued that there is observational evidence for a preferred sense of the Faraday rotation-measure gradients across jets from active galactic nuclei (AGNs). Such behaviour could arise if there were a deterministic relationship between the polarity of the poloidal magnetic field that threads the outflow and the sense of rotation of the outflow's source. Based on this interpretation, Countopoulos et al. suggested that their finding supports a model for the origin of cosmic magnetic fields in a Poynting–Robertson process operating in AGN accretion discs. Here I point out that an alternative explanation of such a relationship could be that the Hall current plays a key role in the magnetohydrodynamics of the underlying disc. In this picture, the measured Faraday rotation is dominated by the contribution of a centrifugally driven wind that is launched from the weakly ionized outer region of the disc. Additional observations are, however, needed to verify the claimed behaviour.