cssi/SciSciGPT-SciSciNet huggingface dataset:
Margin-Based Asset Pricing and Deviations from the Law of One Price

In a model with heterogeneous-risk-aversion agents facing margin constraints, we show how securities’ required returns increase in both their betas and their margin requirements. Negative shocks to fundamentals make margin constraints bind, lowering risk-free rates and raising Sharpe ratios of risky securities, especially for high-margin securities. Such a funding-liquidity crisis gives rise to “bases,” that is, price gaps between securities with identical cash-flows but different margins. In the time series, bases depend on the shadow cost of capital, which can be captured through the interest-rate spread between collateralized and uncollateralized loans and, in the cross-section, they depend on relative margins. We test the model empirically using the credit default swap–bond bases and other deviations from the Law of One Price, and use it to evaluate central banks’ lending facilities. (JEL G01, G12, G13, E44, E50) The paramount role of funding constraints becomes particularly salient during liquidity crises, with the one that started in 2007 being an excellent case in point. Banks unable to fund their operations closed down, and the funding problems spread to other investors, such as hedge funds, that relied on bank funding. Therefore, traditional liquidity providers became forced sellers, interest-rate spreads increased dramatically, Treasury rates dropped sharply, and central banks stretched their balance sheets to facilitate funding. These funding problems had significant asset-pricing effects, the most extreme example being the failure of the Law of One Price (LoOP): Securities with (nearly)
How can we learn whether firm policies are working in africa ? challenges (and solutions?) for experiments and structural models

Firm productivity is low in African countries, prompting governments to try a number of active policies to improve it. Yet despite the millions of dollars spent on these policies, we are far from a situation where we know whether many of them are yielding the desired payoffs. This paper establishes some basic facts about the number and heterogeneity of firms in different sub-Saharan African countries and discusses their implications for experimental and structural approaches towards trying to estimate firm policy impacts. It shows that the typical firm program such as a matching grant scheme or business training program involves only 100 to 300 firms, which are often very heterogeneous in terms of employment and sales levels. As a result, standard experimental designs will lack any power to detect reasonable sized treatment impacts, while structural models which assume common production technologies and few missing markets will be ill-suited to capture the key constraints firms face. Nevertheless, the author suggests a way forward which involves focusing on a more homogeneous sub-sample of firms and collecting a lot more data on them than is typically collected.
Sequential Pd(II)−Pd(0) Catalysis for the Rapid Synthesis of Coumarins

Electrophilic palladium-catalyzed cycloisomerization of brominated aryl propiolates produces brominated coumarins. The brominated coumarins can be diversified by reduction of the Pd(II) catalyst to Pd(0) followed by Suzuki, Sonogashira, Heck, or Hartwig−Buchwald coupling. Thus, a single loading of precatalyst can be used to conduct sequential reactions, allowing the synthesis of functionalized coumarins. Extension of this methodology toward the synthesis of coumarin libraries is discussed.
A family of dunces: trivial RFID identification and authentication protocols

Security and privacy in RFID systems is an important and active research area. A number of challenges arise due to the extremely limited computational, storage and communication abilities of a typical RFID tag. This paper describes a step-by-step construction of a family of simple protocols for inexpensive untraceable identification and authentication of RFID tags. This work is aimed primarily at RFID tags that are capable of performing a small number of inexpensive conventional (as opposed to public key) cryptographic operations. It also represents the first result geared for so-called batch mode of RFID scanning whereby the identification (and/or authentication) of tags is delayed. Proposed protocols involve minimal interaction between a tag and a reader and place very low computational burden on the tag. Notably, they also impose low computational load on back-end servers.
Refining the Oil Curse Country-Level Evidence From Exogenous Variations in Resource Income

Is there a resource curse? Some scholars argue that resource income is associated with slower transitions to democracy; others contend that the negative effects of resources are conditional on factors such as institutional quality. To test these competing hypotheses, this article exploits the price spike caused by the 1973 oil embargo, which transformed several countries with latent oil industries into resource-reliant states. Our quasi-experimental research design allows for better identification of causation than the associational approaches common in the literature. We use the method of synthetic controls to compare the political development of states that received resource-derived revenue with how these states would have behaved in a counterfactual world without such revenue. We find that there is little evidence that a resource curse systematically prevents democratization or that institutional quality alone determines outcomes. Nevertheless, resource income meaningfully affects outcomes and even con...
Sustainability of microfinance self help groups in India: would federating help?

The major form of microfinance in India is that based on women's Self Help Groups (SHGs), which are small groups of 10-20 members. These groups collect savings from their members and provide loans to them. However, unlike most accumulating savings and credit associations (ASCAs) found in several countries, these groups also obtain loans from banks and on-lend them to their members. By 2003, over 700,000 groups had obtained over Rs.20 billion (US$425 million) in loans from banks benefiting more than 10 million people. Delinquencies on these loans are reported to be less than 5 percent. Savings in these groups is estimated to be at least Rs.8 billion (US$170 million). Despite these considerable achievements, sustainability of the SHGs has been suspect because several essential services required by the SHGs are provided free or at a significantly subsidized cost by organizations that have developed these groups. A few promoter organizations have, however, developed federations of SHGs that provide these services and others that SHG members need, but which SHGs cannot feasibly provide. Using a case study approach, Nair explores the merits and constraints of federating. Three SHG federations that provide a wide range of services are studied. The findings suggest that federations could help SHGs become institutionally and financially sustainable because they provide the economies of scale that reduce transaction costs and make the provision of these services viable. But their sustainability is constrained by several factors-both internal, related to the federations themselves, and external, related to the other stakeholders. The author concludes by recommending some actions to address these constraints.
Ca2+ Changes the Force Sensitivity of the Hair-Cell Transduction Channel

The mechanically gated transduction channels of vertebrate hair cells tend to close in ∼1 ms after their activation by hair bundle deflection. This fast adaptation is correlated with a quick negative movement of the bundle (a “twitch”), which can exert force and may mediate an active mechanical amplification of sound stimuli in hearing organs. We used an optical trap to deflect bullfrog hair bundles and to measure bundle movement while controlling Ca2+ entry with a voltage clamp. The twitch elicited by repolarization of the cell varied with force applied to the bundle, going to zero where channels were all open or closed. The force dependence is quantitatively consistent with a model in which a Ca2+-bound channel requires ∼3 pN more force to open, and rules out other models for the site of Ca2+ action. In addition, we characterized a faster, voltage-dependent “flick”, which requires intact tip links but not current through transduction channels.
First Total Synthesis and Stereochemical Definition of Isodomoic Acid G

The first total synthesis and stereochemical definition of isodomoic acid G has been achieved. The key nickel-catalyzed coupling of an alkynyl enone with an alkenylzirconium allows formation of the pyrrolidine ring and most of the stereochemical features in a single step. This report provides the first total synthesis application of this new reaction and illustrates its utility in the stereoselective preparation of highly substituted 1,3-dienes.
STRUCTURES GENERATED BY MODEL NONLINEAR HAMILTONIANS BASED ON OCEAN WAVES

When surface gravity waves in deep water are driven to a balance between energy input and dissipation, it has been observed that the spectrum of wave-height correlations exhibits power-law behavior consistent with the interpretation that over a range of length scales the surface is a self-affine fractal. Zakharov and L’vov long ago invoked a Kolmogorov cascade hypothesis to describe the nonlinear modal transfer of energy which might explain this observation, even in the absence of driving and dissipation. If their hypothesis is correct, a purely autonomous Hamiltonian system would be capable of driving a surface to fractal roughness, in analogy to dynamical system chaos. In this report I summarize a body of recent work aimed at testing the Z-L hypothesis through numerical integration of Zakharov’s Hamiltonian equations. I investigate both scaling and the existence of postulated emergent dynamical times which scale with modenumber. The results are mixed, in ways not easily abstracted. They lead to hard questions regarding the roles of driving and dissipation, and the process of equilibration of the waveheight statistical distribution, which cannot be answered at our present state of knowledge. But I hope that the form of the questions will prove stimulating.
Impacts of Ethanol on Planted Acreage in Market Equilibrium

The magnitude of land conversion caused by biofuels expansion largely determines whether biofuels reduce net greenhouse gas emissions. To examine this issue, we model how equilibrium changes in input use and land allocation decisions respond to market- and policy-induced increases in corn ethanol demand. We demonstrate why total cropland area unambiguously increases with increased ethanol demand. The impact of ethanol price subsidies and consumption mandates are examined in the context of technical change. If ethanol demand is elastic enough, an exogenous increase in corn yields leads to cropland expansion with price subsidies. Yield increases under consumption mandates reduce land use. Copyright 2010, Oxford University Press.
Bone Grafting the Mandible

Many bone grafting techniques have been used to reconstruct the partially dentate and edentulous mandible. This article discusses the various bone grafting techniques to reconstruct mandibular defects. Also included are issues such as whether autogenous bone is necessary for reconstruction of the mandibular ridge and the importance of membranes.
Air fraction estimation for multiple combustion mode diesel engines with dual-loop EGR systems

This paper describes an innovative air fraction estimation method for diesel engines with dual-loop exhaust gas recirculation (EGR) systems to conduct multiple and alternative combustion modes for engine-out emission reduction. An observer is designed to estimate the air fractions in all the engine intake/exhaust sections using standard sensors equipped on the engine. The observer can provide indispensable information for the engine controller to exercise closed-loop control on in-cylinder conditions as well as control the in-cylinder high-pressure EGR gas and low-pressure EGR gas amounts, respectively, which are crucial for engines running alternative combustion modes with dual-loop EGR systems. The convergence stability of the observer is proved based on a Lyapunov analysis assisted by physical insights into the engine/combustion systems. The observer is also experimentally validated on a modern light-duty diesel engine with a dual-loop EGR system.
A Second-Order Projection Method for the Incompressible Navier Stokes Equations on Quadrilateral Grids

This paper describes a second-order projection method for the incompressible Navier-Stokes equations on a logically-rectangular quadrilateral grid. The method uses a second-order fractional step scheme in which one first solves diffusion-convection equations to predict intermediate velocities which are then projected onto the space of divergence-free vector fields. The spatial discretization of the diffusion-convection equations is accomplished by formally transforming the equations to a uniform computational space. The diffusion terms are then discretized using standard finite-difference approximations. The convection terms are discretized using a second-order Godunov method that provides a robust discretization of these terms at high Reynolds number. The projection is approximated using a Galerkin procedure that uses a local basis for discretely divergence-free vector fields. Numerical results are presented illustrating the performance of the method.
The NASA Balloon Program: looking to the future

Abstract The US National Aeronautics and Space Administration (NASA) Balloon Program continues to support the scientific community providing enhanced capabilities across a spectrum of balloon related disciplines. Long Duration Ballooning (LDB) continues to be a prominent element of the program with a mission model of a two flight campaign in each the Northern and Southern Hemispheres per year. A new LDB endurance record was achieved in Antarctica with the LDB/TIGER mission. Both polar and mid-latitude LDB capabilities continue to be on-going operational elements of the flight program. Recently, the balloon LDB platform has been included as a carrier option for the SMEX (SMall EXplorer) and MIDEX (MIDdle EXplorer) Mission announcements of opportunities. Balloon technology efforts have continued to broaden in scope and new plans for activities to provide advancements have been initiated. A new balloon volume record was established with the successful flight of a 1,700,000 m3 volume zero-pressure balloon. The Ultra-Long Duration Balloon (ULDB) project for the development of a 100-day duration balloon capability has been progressing with additional ground and flight tests having been conducted. The Program has also continued to introduce new technology and improvements into flight systems, ground systems and operational techniques. An overview of the various aspects of the NASA Balloon Program will be presented as well as the outlook for the future.
Racial Profiling, Statistical Discrimination, and the Effect of a Colorblind Policy on the Crime Rate

This paper develops a model of racial profiling by law enforcement officers when officers observe both an individual’s race as well as a noisy signal of his or her guilt that depends on whether or not a crime has been committed. The model shows that given officers observe such a guilt signal, data regarding the guilt rate among those investigated from each race will not be sufficient for determining whether racially unequal investigation rates are due to statistical discrimination or racial bias on the part of officers. The model also reveals that when racially unequal investigation rates are due to statistical discrimination, imposing a colorblind policy on officers can increase, decrease, or have little effect on the crime rate, depending on specific characteristics of the jurisdiction and the crime in question.
Enantioselective Functionalization of Radical Intermediates in Redox Catalysis: Copper‐Catalyzed Asymmetric Oxytrifluoromethylation of Alkenes

A method for the efficient enantioselective oxytrifluoromethylation of alkenes has been developed using a copper catalyst system. Mechanistic studies are consistent with a metal-catalyzed redox radical addition mechanism, in which a C–O bond is formed via the copper-mediated enantioselective trapping of a prochiral alkyl radical intermediate derived from the initial trifluoromethyl radical addition.
Uniform Sobolev Inequality along the Sasaki–Ricci Flow

In this paper we prove a uniform Sobolev inequality along the Sasaki–Ricci flow. In the process, we develop the theory of basic Lebesgue and Sobolev function spaces, and prove some general results about the decomposition of the heat kernel for a class of elliptic operators on a Sasaki manifold.
Impulse response confidence intervals for persistent data: What have we learned?

Abstract This paper provides a comprehensive comparison of existing methods for constructing confidence bands for univariate impulse response functions in the presence of high persistence. Monte Carlo results show that the methods proposed in Kilian [1999. Finite-sample properties of percentile and percentile-t bootstrap confidence intervals for impulse responses. Review of Economics and Statistics 81(4), 652–660], Wright [2000. Confidence intervals for univariate impulse responses with a near unit root. Journal of Business and Economic Statistics 18(3), 368–373], Gospodinov [2004. Asymptotic confidence intervals for impulse responses of near-integrated processes. Econometrics Journal 7(2), 505–527] and Pesavento and Rossi [2005. Small sample confidence intervals for multivariate IRFs at long horizons. Journal of Applied Econometrics, forthcoming] have favorable coverage properties, although they differ in terms of robustness at various horizons, median unbiasedness, and reliability in the possible presence of a unit or mildly explosive root. On the other hand, methods like Runkle's [1987. Vector autoregression and reality. Journal of Business and Economic Statistics 5, 437–442] bootstrap, Andrews and Chen [1994. Approximately median-unbiased estimation of autoregressive models. Journal of Business and Economic Statistics 12(2), 187–204] and regressions in levels or first differences (even when based on pre-tests) may not have accurate coverage properties. The paper makes recommendations as to the appropriateness of each method in empirical work.
Combined Ab Initio Computational and Solid-State 17O MAS NMR Studies of Crystalline P2O5.

Ab initio calculations of the 1 7 O electrical field gradient (EFG) tensor quadrupolar coupling constant (C Q ) and asymmetry parameter (η Q ), along with the 1 7 O NMR isotropic chemical shift (δ i s o ) for the three crystalline polymorphs of P 2 O 5 are presented. These computational results are compared with experimental values for crystalline h-P 2 O 5 (hexagonal-form) obtained using a combination of solid-state 1 7 O magic angle spinning (MAS) NMR at three different magnetic field strengths (9.4, 14.1, and 19.6 T), two-dimensional (2D) multiple-quantum (MQ)MAS NMR, and 2D satellite-transition (ST)MAS NMR experiments. In addition ab initio studies of the model H 4 P 2 O 7 cluster allowed empirical correlations between the bridging oxygen EFG parameters and the P-O-P bond angle to be developed.
Schmidt games and Markov partitions

Let T be a C2-expanding self-map of a compact, connected, C∞, Riemannian manifold M. We correct a minor gap in the proof of a theorem from the literature: the set of points whose forward orbits are nondense has full Hausdorff dimension. Our correction allows us to strengthen the theorem. Combining the correction with Schmidt games, we generalize the theorem in dimension one: given a point x0 M, the set of points whose forward orbit closures miss x0 is a winning set. Finally, our key lemma, the no matching lemma, may be of independent interest in the theory of symbolic dynamics or the theory of Markov partitions.
A molecular look at the glomerular barrier.

The glomerular barrier is the kidney's physical block to the unrestricted flow of molecules from the plasma into the urinary space. Its exquisite selectivity allows solutes and water in the glomerular capillaries to pass through, but it prevents the bulk of plasma proteins, most notably albumin, from crossing. Classically, the barrier consists of three distinct components: glomerular endothelium, glomerular basement membrane, and glomerular epithelium (podocytes). In this review, I discuss these three components, with particular emphasis on the barrier presumed to be imparted by a specialized podocyte cell-cell junction, the glomerular slit diaphragm.
PublicationHarvester: An open-source software tool for science policy research☆

We present PublicationHarvester, an open-source software tool for gathering publication information on individual life scientists. The software interfaces with MEDLINE, and allows the end-user to specify up to four MEDLINE-formatted names for each researcher. Using these names along with a user-specified search query, PublicationHarvester generates yearly publication counts, optionally weighted by Journal Impact Factors. These counts are further broken-down by order on the authorship list (first, last, second, next-to-last, middle) and by publication type (clinical trials, regular journal articles, reviews, letters/editorials, etc.) The software also generates a keywords report at the scientist-year level, using the medical subject headings (MeSH) assigned by the National Library of Medicine to each publication indexed by MEDLINE. The software, source code, and user manual can be downloaded at
Financial Development and Technology

Research in development economics reveals that the bulk of cross-country differences in economic growth is attributable to differences in productivity. By some accounts, productivity contributes to more than 60 percent of countries??? growth in per capita GDP. I examine a particular channel through which financial development could explain cross-country and crossindustry differences in realized productivity. I argue that financial development induces technological innovations ??? a major stimulus of productivity - through facilitating capital mobilization and risk sharing. In a panel of industries across thirty eight countries, I find that financial development explains the cross-country differences in industry rates of technological progress, rates of real cost reduction and rates of productivity growth. I find that the effect of financial development on productivity and technological progress is heterogeneous across industrial sectors that differ in their needs for financing innovation. In particular, industries whose younger firms depend more on external finance realize faster rate of technological change in countries with more developed banking sector.
A Robust Distance Measurement and Dark Energy Constraints from the Spherically-Averaged Correlation Function of Sloan Digital Sky Survey Luminous Red Galaxies

We measure the effective distance to z = 0.26, DV (0.26), and mh 2 from the overall shape of the spherically-averaged two-point correlati on function of the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7) volume-limited luminous red galaxy (LRG) sample, without assuming a dark energy model or a flat Universe. We giv e the mean and covariance matrix of DV (0.26), mh 2 , bh 2 , and ns. We show that these provide an efficient and accurate summary of the volume-limited LRG data. With flat priors on bh 2 and ns (7σWMAP7), we find mh 2 = 0.131 ± 0.020, and rs/DV (0.26) = 0.1466 +0.0068 0.0073 (the ratio of the sound horizon at the drag epoch to the effective distance to z = 0.26). We find that measurements of mh 2 or m are biased low if flux-limited (instead of volume-limited) L RG sample is used. By scaling the spherically-averaged correlation fun ction, we find the Hubble parameter H(0.26) = 79 +12 13 km s 1 Mpc 1 and the angular diameter distance DA(0.26) = 848 +86 88 Mpc. Combining our results with the cosmic microwave background and supernova data, we obtain k = 0.0059 +0.0092 0.0093 andw = 1.023 +0.054 0.053 (assuming a constant dark energy equation of state). We use LasDamas SDSS mock catalogs to compute the covariance matrix of the correlation function, and investigate the use of lognormal catal ogs as an alternative. We find that the input correlation function can be accurately recovered from lognormal catalogs, although they give larger errors on all scales (especially on small sc ales) compared to the mock catalogs derived from cosmological N-body simulations.
Endothelial Cell Heterogeneity

The endothelial lining of blood vessels shows remarkable heterogeneity in structure and function, in time and space, and in health and disease. An understanding of the molecular basis for phenotypic heterogeneity may provide important insights into vascular bed-specific therapies. First, we review the scope of endothelial heterogeneity and discuss its proximate and evolutionary mechanisms. Second, we apply these principles, together with their therapeutic implications, to a representative vascular bed in disease, namely, tumor endothelium.
Resonance-Line Scattering in Supernova Remnant Shocks

We present a three-dimensional radiative transfer model to examine the effects of resonance-line scattering in the postshock flow behind a nonradiative supernova remnant shock. For a rippled shock front viewed edge-on, line scattering significantly reduces the observed flux of C IV λ1549 and N V λ1240, two important diagnostic lines in the ultraviolet spectra of supernova remnants. The correction factor (defined to be the ratio of the line flux that would be observed neglecting scattering to the actual observed line flux) is a function of position within the filament. For sufficiently large regions that include crisp edges as well as more diffuse regions of the filament structure, the C IV and N V correction factors are between about 1.5 and 3.5 (and the C IV correction factor is invariably larger than the N V correction factor). The correction factors have a larger range when smaller regions are considered. The C IV correction factor is about 6 at the filament edges, while the N V correction factor is about 4. These simulations of resonance-line scattering will be useful for the analysis of supernova remnant shock spectra.
Changes in the prominence of the eyes in various thyroid states.

FOLLOWING thyroidectomy for exophthalmic goiter there frequently occurs an increase in the prominence of the eyes even though the patient's gross appearance suggests improvement in the exophthalmos. This observation was reported by Soley (3) in 1942 and (4, 5,) 1944, and confirmed by Dobyns (2) in 1945. As a sequel to studies described elsewhere we have studied by actual measurements the changes in the prominence of the eyes in other pathologic thyroid states during the course of various kinds of treatment. METHOD As previously described in another communication (2), the eyes of these patients have been measured with the Hurtel exophthalmometer. All measurements were made by the same observer who used the same instrument which was set at the same interocular setting for any one patient. The measurements were made as nearly as possible at the same time of day (about noon). The present study is a continuation of a former one in which several thousand measurements on the eye were made. Methods thus were well...
Some results on embeddings of algebras, after de Bruijn and McKenzie

Abstract In 1957, N.G. de Bruijn showed that the symmetric group Sym(Ω) on an infinite set Ω contains a free subgroup on 2card(Ω) generators, and proved a more general statement, a sample consequence of which is that for any group A of cardinality ⩽ card(Ω), the group Sym(Ω) contains a coproduct of 2card(Ω) copies of A, not only in the variety of all groups, but in any variety of groups to which A belongs. His key lemma is here generalized to an arbitrary variety of algebras V, and formulated as a statement about functors Set ℩ V. From this one easily obtains analogs of the results stated above with “group” and Sym(Ω) replaced by “monoid” and the monoid Self(Ω) of endomaps of Ω, by “associative K-algebra” and the K-algebra EndK (V) of endomorphisms of a K-vector-space V with basis Ω, and by “lattice” and the lattice Equiv(Ω) of equivalence relations on Ω. It is also shown, extending another result from de Bruijn's 1957 paper, that each of Sym(Ω), Self(Ω) and EndK(V) contains a coproduct of 2card(Ω) copies of itself. That paper also gave an example of a group of cardinality 2card(Ω) that was not embeddable in Sym(Ω), and R. McKenzie subsequently established a large class of such examples. Those results are shown here to be instances of a general property of the lattice of solution sets in Sym(Ω) of sets of equations with constants in Sym(Ω). Again, similar results - this time of varying strengths - are obtained for Self(Ω), EndK(V), and Equiv(Ω), and also for the monoid Rel(Ω) of binary relations on Ω. Many open questions and areas for further investigation are noted.
Low-Frequency Quantum-Based AC Power Standard at NRC Canada

A low-frequency AC power standard based on the programmable Josephson voltage standard (PJVS) has been developed at the National Research Council of Canada. At the step voltages, PJVS provides quantum accuracy. Differential digital sampling is used to extend the quantum accuracy to the AC power standard output voltage and current, nominally 120 V and 5 A. The paper describes the power standard and its evaluation.
Barriers to Competition and Productivity: Evidence from India

A number of economic theories suggest that barriers to competition lead to higher levels of inefficiency among incumbents. In this paper, we use a detailed plant-level dataset to study the impact on productivity of two reforms (initiated in 1991) aimed at increasing product market competition in India -- liberalization of foreign direct investment (FDI) and reduction in tariff rates. First, we examine the effect of the liberalization policies on mean plant-level productivity in the targeted industries. We find significant increases in productivity in the FDI and tariff-liberalized industries, particularly in the longer term (1993-94). We check and find our results robust to a range of robustness tests. Next, we examine the role of intensive (within-plant productivity growth) and extensive (reallocation from less to more productive plants) margins in the post-reform productivity improvement, and find a predominant role for the former. Finally, we assess potential channels for within-firm productivity improvement. Consistent with a role for price competition, we find evidence of greater declines in output prices as well as concentration measures in the liberalized sectors.
Neighborhood Effects on the Long-Term Well-Being of Low-Income Adults

Nearly 9 million Americans live in extreme-poverty neighborhoods, places that also tend to be racially segregated and dangerous. Yet, the effects on the well-being of residents of moving out of such communities into less distressed areas remain uncertain. Using data from Moving to Opportunity, a unique randomized housing mobility experiment, we found that moving from a high-poverty to lower-poverty neighborhood leads to long-term (10- to 15-year) improvements in adult physical and mental health and subjective well-being, despite not affecting economic self-sufficiency. A 1–standard deviation decline in neighborhood poverty (13 percentage points) increases subjective well-being by an amount equal to the gap in subjective well-being between people whose annual incomes differ by $13,000—a large amount given that the average control group income is $20,000. Subjective well-being is more strongly affected by changes in neighborhood economic disadvantage than racial segregation, which is important because racial segregation has been declining since 1970, but income segregation has been increasing.
An on-line algorithm for improving performance in navigation

Recent papers have shown optimally-competitive on-line strategies for a robot traveling from a point s to a point t in certain unknown geometric environments. We consider the question: Having gained some partial information about the scene on its first trip from s to t, can the robot improve its performance on subsequent trips it might make? This is a type of on-line problem where a strategy must exploit partial information about the future (e.g., about obstacles that lie ahead). For scenes with axis-parallel rectangular obstacles where the Euclidean distance between s and t is n, we present a deterministic algorithm whose average trip length after t trips, k/spl les/n, is O(/spl radic/n/k) times the length of the shortest s-t path in the scene. We also show that this is the best a deterministic strategy can do. This algorithm can be thought of as performing an optimal tradeoff between search effort and the goodness of the path found. We improve this algorithm so that for every i/spl les/n, the robot's ith trip length is O(/spl radic/n/t) times the shortest s-t path length. A key idea of the paper is that a tree structure can be defined in the scene, where the nodes are portions of certain obstacles and the edges are "short" paths from a node to its children. The core of our algorithms is an on-line strategy for traversing this tree optimally. >
The Expert's Opinion

INTERVIEWEE PROFILE: GE Information Services, Inc., a global leader in electronic commerce services, provides commerce express, electronic messaging, electronic data interchange, and information management services along with consulting and systems integration and implementation to link more than 25,000 businesses around the world. Headquartered in Rockville, Maryland, GE Information Services, Inc. is a subsidiary of GE, a global technology services and manufacturing company.
Market Penetration Costs and Trade Dynamics

I introduce trade dynamics into a static model of international trade with product differentiation, heterogeneous productivity firms, and increasing marginal market penetration costs. I interpret firms as ideas that materialize into production, where a ni dea is aw ay to produce a differentiated good with a given productivity. Adapting a stochastic process similar to Reed, the model endogenously generates a right tail cross-sectional Pareto distribution of firms’ productivities based on two minimal assumptions: continuous entry of ideas at a certain rate and productivities of ideas that evolve according to a geometric Brownian motion. The cross-sectional predictions of the model for the distribution of domestic and exporting sales of firms are in line with firm-level data. In addition, the model delivers new predictions consistent with observations of the dynamics of domestic and exporting sales of firms. It predicts that many small firms enter and exit the market very frequently and that the growth rate as well as the variance of the growth rate of sales is higher for small firms.
Directed search without wage commitment: a new role for minimum wages and unions.

An urn-ball matching model of directed search is analyzed in which the usual assumption of commitment to posted wages is dropped. One-on-one matches lead to a Nash bargained wage but when multiple applicants arrive Bertrand competition means that workers only get their outside option. A minimum wage can act as a commitment device when willful under payment carries a stiffer penalty than inadvertent underpayment. The theory sheds new light on why firms appear to voluntarily bind themselves into paying higher wages than they would otherwise pay.
Long-term consequences of an innovative redundancy - retraining project : the Austrian Steel Foundation

In the late 1980s, privatization and downsizing of nationalized steel mills, and related firms in the metal industry, have lead to large-scale redundancy plans. A special Steel Foundation was created as part of a social plan. This foundation acted like an independent training center, where displaced workers would spend relatively long training periods, obtaining personality and orientation training, as well as formal education. The last step of the integrative program was placement assistance, as well as assistance for creating one's own business. The foundation was financed by (higher) contributions from unemployment insurance funds, by the previous firms themselves, as well as by a collectively-bargained special tax on the remaining workers in the steel firms. Moreover, the trainees themselves would have to support the foundation by giving up the interest accruing to their redundancy payments. The report combined data from Austrian social security records, and from the Employment Service, to look at participation decisions, and at post-foundation economic performance. Then, as a control group, all displaced workers were taken into consideration, using instrumental variables to solve the selection problem. Results show considerable wage gains - even for a period of five years after leaving the Foundation - as well as improved employments prospects, and, finally, a cost-benefit analysis assesses the long-term success of the Foundation.
Crystal engineering of NLO materials based on metal-organic coordination networks

Crystal engineering, the ability to predict and control the packing of molecular building units in the solid state, has attracted much attention over the past three decades owing to its potential exploitation for the synthesis of technologically important materials. We present here the development of crystal-engineering strategies toward the synthesis of noncentrosymmetric infinite coordination networks for use as second-order nonlinear optical (NLO) materials. Work performed mainly in our laboratory has demonstrated that noncentrosymmetric solids based on infinite networks can be rationally synthesized by combining unsymmetrical bridging ligands and metal centers with well-defined coordination geometries. Specifically, coordination networks based on 3D diamondoid and 2D grid structures can be successfully engineered with a high degree of probability and predictability to crystallize in noncentrosymmetric space groups. We have also included noncentrosymmetric solids based on 1D chains and related helical structures for comparison.
The AWGN Red Alert Problem

Consider the following unequal error protection scenario. One special message, dubbed the “red alert” message, is required to have an extremely small probability of missed detection. The remainder of the messages must keep their average probability of error and probability of false alarm below a certain threshold. The goal then is to design a codebook that maximizes the error exponent of the red alert message while ensuring that the average probability of error and probability of false alarm go to zero as the blocklength goes to infinity. This red alert exponent has previously been characterized for discrete memoryless channels. This paper completely characterizes the optimal red alert exponent for additive white Gaussian noise channels with block power constraints.
The Effects of Kin on Primate Life Histories

Advances in our understanding of primate life histories and dispersal patterns provide insights into the ways in which facultative responses to local ecological and demographic conditions are mediated by phylogenetic constraints. The long life spans characteristic of primates provide the necessary conditions for overlapping generations of related individuals to maintain extended kin bonds. Dispersal regimes dictate the opportunities for biological kin to interact with one another and define the range of potential reproductive and social partners within and beyond their natal groups. Dispersal patterns also affect variation in components of life histories such as female age at first reproduction, reproductive rates, and trade-offs between investment in current vs. future offspring and extended kin. Understanding these dynamics has important implications for assessing the viability of small populations and the ability of different primates to adapt.
A neuroidal architecture for cognitive computation

An architecture is described for designing systems that acquire and ma nipulate large amounts of unsystematized, or so-called commonsense, knowledge. Its aim is to exploit to the full those aspects of computational learning that are known to offer powerful solutions in the acquisition and maintenance of robust knowledge bases. The architecture makes explicit the requirements on the basic computational tasks that are to be performed and is designed to make this computationally tractable even for very large databases. The main claims are that (i) the basic learning and deduction tasks are provably tractable and (ii) tractable learning offers viable approaches to a range of issues that have been previously identified as problematic for artificial intelligence systems that are programmed. Among the issues that learning offers to resolve are robustness to inconsistencies, robustness to incomplete information and resolving among alternatives. Attribute-efficient learning algorithms, which allow learning from few examples in large dimensional systems, are fundamental to the approach. Underpinning the overall architecture is a new principled approach to manipulating relations in learning systems. This approach, of independently quantified arguments, allows propositional learning algorithms to be applied systematically to learning relational concepts in polynomial time and in modular fashion.
Chandrasekhar equations for infinite dimensional systems

In this paper we derive the Chandrasekhar equations for linear time invariant systems defined on Hilbert spaces using a functional analytic technique. An important consequence of this is that the solution to the evolutional Riccati equation is strongly differentiable in time and one can define a “strong” solution of the Riccati differential equation. A detailed discussion on the linear quadratic optimal problem for hereditary differential systems is also included.
Chandra X-Ray Observatory

First page of article Keywords: Chandra x-ray observatory (CXO); Chandra images of globular clusters
The impact of social navigation on privacy policy configuration

Social navigation is a promising approach to help users make better privacy and security decisions using community knowledge and expertise. Social navigation has recently been applied to several privacy and security systems such as peer-to-peer file sharing, cookie management, and firewalls. However, little empirical evaluation of social navigation cues has been performed in security or privacy systems to understand the real impact such knowledge has on user behavior and the resulting policies. In this paper, we explore the application of social navigation to access control policy configuration using an empirical between subjects study. Our results indicate that community information does impact user behavior, but only when the visual representation of the cue is sufficiently strong.
Single conversion VHF/UHF receiver design and the impact of monolithic technology

With the advent of monolithic crystal filters and monolithic integrated circuits, single conversion VHF/UHF land-mobile receivers have attracted the attention and enthusiasm of receiver designers and users alike. Single-conversion receivers represent the standard of excellence in terms of performance and reliability. With monolithic technology, they can be cost competitive with conventional double-conversion receivers, especially in the design of high performance land-mobile receivers. This paper will discuss the important benefits and the design tradeoffs of single-conversion receivers with a specific emphasis on the impact of monolithic technology.
Managing Disruption Risk: The Interplay Between Operations and Insurance

Disruptive events that halt production can have severe business consequences if not appropriately managed. Business interruption (BI) insurance offers firms a financial mechanism for managing their exposure to disruption risk. Firms can also avail of operational measures to manage the risk. In this paper, we explore the relationship between BI insurance and operational measures. We model a manufacturing firm that can purchase BI insurance, invest in inventory, and avail of emergency sourcing. Allowing the insurance premium to depend on the firm's insurance and operational decisions, we characterize the optimal insurance deductible and coverage limit as well as the optimal inventory level. We prove that insurance and operational measures are not always substitutes, and we establish conditions under which they can be complements; that is, insurance can increase the marginal value of inventory and can increase the overall value of emergency sourcing. We also find that the value of insurance is higher for those firms less able to absorb financially significant disruptions. As disruptions become longer but rarer, the value of emergency sourcing increases, and the value of inventory and the value of insurance increase before eventually decreasing. This paper was accepted by Martin Lariviere, operations management.
Channel Simulation to Facilitate Mobile-Satellite Communications Research

In designing a mobile satellite network, engineers and technologists are faced with wide-ranging issues for which there is no prior database. System engineers must address such issues as adequate margin to combat multipath fading, the level of adjacent channel protection required to allow transmission in narrow-band channels, the cochannel protection required to allow for frequency reuse in a multiplebeam system, and the level of intermodulation distortion tolerable for single-channel-per-carrier operation. Technologists, on the other hand, must determine the performance of various system components. For example, in the ground segment, modem and speech codec performance must be evaluated in the presence of thermal noise, fading, and other impairments. To enable system designers and technologists to optimize their design and pursue their research and development, the Jet Propulsion Laboratory has developed a mobile satellite channel simulator in hardware. This simulator has sufficient flexibility to facilitate many forms of tests and experiments.
Combined pressure and temperature distortion effects on internal flow of a turbofan engine

An additional data base for improving and verifying a computer simulation developed by an engine manufacturer was obtained. The multisegment parallel compressor simulation was designed to predict the effects of steady-state circumferential inlet total-pressure and total-temperature distortions on the flows into and through a turbofan compression system. It also predicts the degree of distortion that will result in surge of the compressor. The effect of combined 180 deg square-wave distortion patterns of total pressure and total temperature in various relative positions is reported. The observed effects of the combined distortion on a unitary bypass ratio turbofan engine are presented in terms of total and static pressure profiles and total temperature profiles at stations ahead of the inlet guide vanes as well as through the fan-compressor system. These observed profiles are compared with those predicted by the complex multisegment model. The effects of relative position of the two components comprising the combined distortion on the degree resulting in surge are discussed. Certain relative positions required less combined distortion than either a temperature or pressure distortion by itself.