cssi/SciSciGPT-SciSciNet huggingface dataset:
Collapsing and Dirac-Type Operators

We analyze the limit of the spectrum of a geometric Dirac-type operator under a collapse with bounded diameter and bounded sectional curvature. In the case of a smooth limit space B, we show that the limit of the spectrum is given by the spectrum of a certain ¢rst-order differential operator on B, which can be constructed using superconnections. In the case of a general limit space X, we express the limit operator in terms of a transversally elliptic operator on a G-manifold � X with X ¼ � X =G. As an application, we give a characterization of manifolds which do not admit uniform upper bounds, in terms of diameter and sectional curvature, on the k-th eigenvalue of the square of a Dirac-type operator.We also give a formula for the essential spectrum of a Dirac-type operator on a ¢nite-volume manifold with pinched negative sectional curvature.
Scale Economies and Consolidation in Hog Slaughter

We use establishment based panel data to estimate a cost function which identifies the role of scale economies in hog slaughter consolidation. We find modest but extensive technological scale economies in the 1990s, and they became more important over time. But wages rose sharply with plant size through the 1970s, and those wage premiums generated a pecuniary scale diseconomy that largely offset the effects of technological scale economies. The size-wage relation disappeared in the 1980s; with growing technological scale economies and disappearing pecuniary diseconomies, large plants realized growing cost advantages over smaller plants, and production shifted to larger plants. Copyright 2000, Oxford University Press.
Equilibrium Concepts for Social Interaction Models

This paper describes the relationship between two different binary choice social interaction models. The Brock and Durlauf (2001) model is essentially a static Nash equilibrium model with random utility preferences. In the Blume (2003) model is a population game model similar to Blume (1993), Kandori, Mailath and Rob (1993) and Young (1993). We show that the equilibria of the Brock–Durlauf model are steady states of a differential equation which is a deterministic approximation of the sample-path behavior of Blume's model. Moreover, the limit distribution of this model clusters around a subset of the steady states when the population is large.
ABSORPTIVE CAPACITY: A NEW PERSPECTIVE ON LEARNING AND INNOVATION

In this paper, we argue that the ability of a firm to recognize the value of new, external information, assimilate it, and apply it to commercial ends is critical to its innovative capabilities. We label this capability a firm's absorptive capacity and suggest that it is largely a function of the firm's level of prior related knowledge. The discussion focuses first on the cognitive basis for an individual's absorptive capacity including, in particular, prior related knowledge and diversity of background. We then characterize the factors that influence absorptive capacity at the organizational level, how an organization's absorptive capacity differs from that of its individual members, and the role of diversity of expertise within an organization. We argue that the development of absorptive capacity, and, in turn, innovative performance are history- or path-dependent and argue how lack of investment in an area of expertise early on may foreclose the future development of a technical capability in that area. We formulate a model of firm investment in research and development (R&D), in which R&D contributes to a firm's absorptive capacity, and test predictions relating a firm's investment in R&D to the knowledge underlying technical change within an industry. Discussion focuses on the implications of absorptive capacity for the analysis of other related innovative activities, including basic research, the adoption and diffusion of innovations, and decisions to participate in cooperative R&D ventures. **
Stability of underdominant genetic polymorphisms in population networks

Heterozygote disadvantage is potentially a potent driver of population genetic divergence. Also referred to as underdominance, this phenomena describes a situation where a genetic heterozygote has a lower overall fitness than either homozygote. Attention so far has mostly been given to underdominance within a single population and the maintenance of genetic differences between two populations exchanging migrants. Here we explore the dynamics of an underdominant system in a network of multiple discrete, yet interconnected, populations. Stability of genetic differences in response to increases in migration in various topological networks is assessed. The network topology can have a dominant and occasionally non-intuitive influence on the genetic stability of the system.
The Globular Cluster System in the Outer Regions of NGC 4472

We have undertaken a study of the globular cluster (GC) systems of a large sample of elliptical and spiral galaxies in order to test specific predictions of galaxy formation models. Here we present results for the first elliptical in the study, the giant Virgo cluster galaxy NGC 4472 (M49). The galaxy was observed in three filters (BVR) using the wide-field Mosaic Imager on the Kitt Peak 4 m telescope. The Mosaic images roughly double the radial coverage of previous CCD observations of NGC 4472. We have combined the Mosaic data with published spectroscopic data and archival HST observations in order to study NGC 4472's GC system in detail, and to fully characterize the amount of contamination in our sample of GC candidates. We find that the radial profile of the GC system is fit fairly well by a de Vaucouleurs law of the form log σGC = (3.38 ± 0.08) - (1.56 ± 0.05) r1/4 out to 17' (~80 kpc), but that the observed profile falls slightly below the de Vaucouleurs law between 17' and 23', the limit of the data. The bimodal color distribution observed in previous studies is apparent in our data. We find a small metallicity gradient in the inner 8' of the total GC system due to the increasing ratio of blue to red clusters, consistent with results from past studies. The gradient vanishes, however, when the entire radial extent of the data is taken into account. We estimate a total of ~5900 GCs in NGC 4472 out to 23', yielding a specific frequency of 3.6 ± 0.6 within this radius. This specific frequency value is smaller than that found by previous studies of NGC 4472. We examine the implications of these results with regard to predictions made by four different galaxy formation models, and we find that all four models have at least one inconsistency with the data.
The Folk Theorem for Games with Private Almost‐Perfect Monitoring

We prove the folk theorem for discounted repeated games under private, almost-perfect monitoring. Our result covers all finite, n-player games that satisfy the usual full-dimensionality condition. Mixed strategies are allowed in determining the individually rational payoffs. We assume no cheap-talk communication between players and no public randomization device.
A Theory of the Trojan Asteroids

The paper constructs a long-periodic solution for the case of 1:1 resonance in the restricted problem of three bodies. The polar coordinates r and 0 appear in the form $$\begin{array}{l} r = r\left( \lambda \right) - m\left| {{c_k}} \right|\cos \left( {k{\omega _1}t + \phi } \right)/D\\ \theta = \theta \left( \lambda \right) + 2m\left| {{c_k}} \right|\sin \left( {k{ _1}t + \phi } \right)/D\\ \lambda = \lambda \left( t \right), D = {\omega _2} - k{\omega _1}. \end{array}$$ Here λ is the mean synodic longitude, m is the small mass-parameter, k is the integer nearest to the ratio ω2/ω1 of the fundamental angular frequencies of the motion, and ck is a Fourier coefficient of a certain periodic function. Only elementary functions enter r(λ) and θ(λ), while the calculation of λ(t) requires the inversion of a hyper-elliptic integral t(λ).
Efficient uncertainty propagation for network multiphysics systems

SUMMARY We consider a multiphysics system with multiple component PDE models coupled together through network coupling interfaces, that is, a handful of scalars. If each component model contains uncertainties represented by a set of parameters, a straightforward uncertainty quantification study would collect all uncertainties into a single set and treat the multiphysics model as a black box. Such an approach ignores the rich structure of the multiphysics system, and the combined space of uncertainties can have a large dimension that prohibits the use of polynomial surrogate models. We propose an intrusive methodology that exploits the structure of the network coupled multiphysics system to efficiently construct a polynomial surrogate of the model output as a function of uncertain inputs. Using a nonlinear elimination strategy, we treat the solution as a composite function: the model outputs are functions of the coupling terms, which are functions of the uncertain parameters. The composite structure allows us to construct and employ a reduced polynomial basis that depends on the coupling terms. The basis can be constructed with many fewer PDE solves than the naive approach, which results in substantial computational savings. We demonstrate the method on an idealized model of a nuclear reactor. Copyright © 2014 John Wiley & Sons, Ltd.
Technological Competition and the Structure of the Computer Industry

We examine thirty years of computer industry market structure. Our analysis explains the persistence of dominant computer firms, their recent decline, and the changing success of competitive entry. It emphasizes the importance of technological competition between computer ‘platforms’, not firms. This aspect of competition has changed little over time. Two things did change. Young platforms serving newly founded segments eventually challenged established platforms across segment boundaries through a process of indirect entry. Vertically disintegrated platforms have led to divided technical leadership in important segments. The result is an industry with far more technological competition.
Solving non-Markovian open quantum systems with multi-channel reservoir coupling

Abstract We extend the non-Markovian quantum state diffusion (QSD) equation to open quantum systems which exhibit multi-channel coupling to a harmonic oscillator reservoir. Open quantum systems which have multi-channel reservoir coupling are those in which canonical transformation of reservoir modes cannot reduce the number of reservoir operators appearing in the interaction Hamiltonian to one. We show that the non-Markovian QSD equation for multi-channel reservoir coupling can, in some cases, lead to an exact master equation which we derive. We then derive the exact master equation for the three-level system in a vee-type configuration which has multi-channel reservoir coupling and give the analytical solution. Finally, we examine the evolution of the three-level vee-type system with generalized Ornstein–Uhlenbeck reservoir correlations numerically.
Long-range interaction effects on neutrino oscillation

Motivated by the recent anomaly in the muon neutrino and anti-muon neutrino disappearance experiments, we consider a long-range interaction with an extremely light gauge boson and extraordinarily weak coupling. A long-range interaction, consistent with current bounds, could have very pronounced effects on atmospheric neutrino disappearance that will be studied with the IceCube DeepCore array, currently in operation, and can have a significant effect on future high-precision long-baseline oscillation experiments. This invited talk was based on the paper with Hooman Davoudiasl and William Marciano [1].
Topological Correlators in Landau-Ginzburg Models with Boundaries

We compute topological correlators in Landau-Ginzburg models on a Riemann surface with arbitrary number of handles and boundaries. The boundaries may correspond to arbitrary topological D-branes of type B. We also allow arbitrary operator insertions on the boundary and in the bulk. The answer is given by an explicit formula which can be regarded as an open-string generalization of C. Vafa's formula for closed-string topological correlators. We discuss how to extend our results to the case of Landau-Ginzburg orbifolds.
Optimizing T-violating effects for neutrino oscillations in matter

Abstract Matter effects may strongly enhance the Jarlskog factor J in T- and CP-violating three-neutrino oscillation probabilities. However, we show that when J is enhanced, the same matter effects suppress the oscillating factors and increase the oscillation length. The net result is that there is no large enhancement in measurable probabilities for earth-bound experiments using neutrino parameters suggested by current experiments. We show that by an appropriate choice of the experimental parameters, neutrino energy and travel length, the T-violating probability can be enhanced by matter effects over their vacuum values by 50%. Our approach is analytical, allowing considerable insight into the underlying physics.
Digital reconstruction of axially thick potentials

The holographic reconstruction of objects typically assumes that the object is axially thin. Here, we demonstrate a simple approach that works for axially-thick potentials which evolve dynamically. Results are verified by reconstructing linear scattering experiments.
FOUR-DIMENSIONAL BLACK HOLES AND STRINGS WITH RESCALED TENSION

We give a microscopic description of extreme and near-extreme Reissner–Nordstrom black holes in four dimensions in terms of fundamental strings in a background of magnetic five branes and monopoles. The string oscillator numbers and tension are rescaled due to the Rindler space background with the string mass fixed. The entropy of the black holes is reproduced correctly by that of the string by taking into account the tension rescaling.
Assessing the Impact of Stricter Food Safety Standards on Trade:HACCP in U.S. Seafood Trade with the Developing World

Health risks associated with seafood products prompted the introduction of mandatory HACCP in the seafood industry in the United States in 1997. This paper quantifies the trade impact of this introduction by analyzing patterns of seafood imports to the U.S. over the period 1990 to 2004. The results of a gravity model using panel data suggest that HACCP had a negative and significant impact on overall seafood imports from the top 33 developing and developed countries selling into the U.S. For developing countries, the results support the view of "standards-as-barriers" versus "standards-as-catalysts" as the negative HACCP effect was experienced by developing countries, while the effect for developed countries was positive.
Elastic/viscoplastic behavior of fiber-reinforced thermoplastic composites

An elastic/viscoplastic constitutive model was used to characterize the nonlinear and rate dependent behavior of a continuous fiber-reinforced thermoplastic composite. This model was incorporated into a finite element program for the analysis of laminated plates and shells. Details on the finite element formulation with the proposed constitutive model were presented. The numerical results were compared with experimental data for uniaxial tension and three-point bending tests of (+ or - 45 deg)3s APC-2 laminates.
CENTRAL LIMIT THEOREM FOR LINEAR STATISTICS OF EIGENVALUES OF BAND RANDOM MATRICES

We prove the Central Limit Theorem for linear statistics of the eigenvalues of band random matrices provided $\sqrt{n} \ll b_n \ll n$ and test functions are sufficiently smooth.
The COBE DIRBE Search for the Cosmic Infrared Background

The Diffuse Infrared Background Experiment (DIRBE) on the Cosmic Background Explorer (COBE) satellite is designed to conduct a sensitive search for isotropic cosmic infrared background radiation over the spectral range from 1.25 to 240 µm. The cumulative emissions of pregalactic, protogalactic, and evolving galactic systems are expected to be recorded in this background. The DIRBE instrument has mapped the full sky with high redundancy at solar elongation angles ranging from 64°to 124°to facilitate separation of interplanetary, Galactic, and extragalactic sources of emission. Conservative limits on the isotropic infrared background are given by the minimum observed sky brightnesses in each DIRBE spectral band during the 10 months of cryogenic operation. Extensive modeling of the foregrounds is under way to isolate or strongly limit the extragalactic infrared component. The current approach to these modeling efforts is described and representative present residuals are reported.
Structure and function of "metalloantibiotics".

Although most antibiotics do not need metal ions for their biological activities, there are a number of antibiotics that require metal ions to function properly, such as bleomycin (BLM), streptonigrin (SN), and bacitracin. The coordinated metal ions in these antibiotics play an important role in maintaining proper structure and/or function of these antibiotics. Removal of the metal ions from these antibiotics can cause changes in structure and/or function of these antibiotics. Similar to the case of “metalloproteins,” these antibiotics are dubbed “metalloantibiotics” which are the title subjects of this review. Metalloantibiotics can interact with several different kinds of biomolecules, including DNA, RNA, proteins, receptors, and lipids, rendering their unique and specific bioactivities. In addition to the microbial-originated metalloantibiotics, many metalloantibiotic derivatives and metal complexes of synthetic ligands also show antibacterial, antiviral, and anti-neoplastic activities which are also briefly discussed to provide a broad sense of the term “metalloantibiotics.” © 2003 Wiley Periodicals, Inc. Med Res Rev, 23 No. 6, 697–762, 2003
A new synthesis of aryl mono C-glycosyl derivatives of dialdehyde sugars

Synthese de (1,2:3,4-di-O-isopropylidene-5-[4,5,8-triacetoxy-2-naphtyl]) arabinopyranose a partir essentiellement de (1,2:3,4-di-O-isopropylidene-5-[1-(trimethylsiloxy) vinyl]) arabinopyranose et de 2-acetyl 1,4-benzoquinone
Country Fund Discounts and the Mexican Crisis of December 1994: Did Local Residents Turn Pessimistic Before International Investors?

It has been suggested that Mexican investors were the “front-runners” in the peso crisis of December 1994, turning pessimistic before international investors. Different expectations about their own economy, perhaps due to asymmetric information, prompted Mexican investors to be the first ones to leave the country. This paper investigates whether data from three Mexican country funds provide evidence that supports the “divergent expectations” hypothesis. We find that, right before the devaluation, Mexican fund Net Asset Values (mainly driven by Mexican investors) dropped first and/or faster than Mexican country fund prices (mainly driven by foreign investors). Moreover, we find that Mexican NAVs tend to Granger-cause the country fund prices. This suggests that causality, in some sense, flows from the Mexico City investor community to the Wall Street investor community.
Photopolymerization in Cholesteric Mesophases

Abstract Cholesteric liquid crystalline monomers undergo efficient photopolymerization to “freeze in” the planar texture characteristic of low molar mass cholesteric liquid crystals. The monomers consist of polymerizable moieties separated from the cholesteryl mesogens by flexible spacer groups. Individual monomers and mixtures give homopolymers and copolymers, respectively, that exhibit cholesteric textures to within 10 to 15[ddot]C of the isotropic transition.
Bounce-and-skip. A technique for directing the flow of control in programs

A new technique for directing the flow of control in block structured programs is described. It allows a programmer to delay using the outcome of a test indefinitely, and to make the entry and exit of begin-end blocks conditional upon the last test performed. This technique is the main tool for directing the flow of control in the programming language Nucleol, and is considered to be particularly useful for program debugging.
Hybridization of SBR and FEM for scattering by large bodies with cracks and cavities

High-frequency methods, such as shooting-and-bouncing-ray (SBR) [Ling et al., 1989], are very efficient for computing electromagnetic scattering from large targets whose sizes are on the order of tens or hundreds of wavelengths. However, they cannot incorporate the contributions from small features such as cracks, gaps, cavities, and microstrip patch antennas, whose smallest dimension is on the order of a fraction of a wavelength. Therefore, a high-frequency method alone cannot accurately treat large and complex targets with these small features. In the present paper, the authors present a robust hybrid technique to remove this limitation on high-frequency methods. This new technique combines a high-frequency method with a low-frequency method in such a manner that (i) it includes all significant interactions between the large target and the small features and (ii) it permits the high-frequency and low-frequency methods to be computed separately. The low-frequency method employed is the finite element method (FEM), which is well-known for its capability to model complex geometries and inhomogeneous materials.
Universal NMR databases for contiguous polyols

On the basis of 1,2,3-triols 1a∼d, 1,2,3,4-tetraols 2a∼h, and 1,2,3,4,5-pentaols 3a∼p, NMR databases with four types of profile-descriptors (13C-, 1H-, and 1H(OH)-chemical shifts and vicinal spin-coupling constants) for contiguous polyols are reported. To systematically assess the relative values of these databases, a case study has been conducted on heptaols 4a∼d, through which the γ- and δ-effects have been recognized to refine the 13C and 1H chemical shift profile predicted via an application of the concept of self-contained nature. The magnitudes of γ- and δ-effects depend on a specific stereochemical arrangement of the functional groups present in both the inside and outside of a self-contained box and are significant only for the stereoisomers belonging to a specific sub-group. With the exception of the stereochemical arrangement of functional groups belonging to a specific sub-group, the γ- and δ-effects can, at the first order of approximation, be ignored for the stereochemical analysis of unknown...
FAILURE DETECTION BY PILOTS DURING AUTOMATIC LANDING: MODELS AND EXPERIMENTS

A model is proposed to describe the pilot as a monitor of automatic landing systems. The failures treated are equivalent to the addition of a dynamic change in the mean of the observation process. The failure detection model of the pilot consists of two stages: a linear estimator (Kalman filter) and a decision mechanism based on sequential analysis. The filter equations are derived from a simplified version of the linearized dynamics of the airplane and the control loop. The perceptual observation noise is modified to include the effects of allocation of attention among the several instruments. The final result is a simple model consisting of a high-pass filter to produce the observation residuals and a decision function which is a pure integration of the residuals minus a bias term. The dynamics of a Boeing 707 were used to simulate the fully coupled final approach in a fixed-base simulator. Observers monitored the approaches and detected the failures; their performance was compared with the predictions of the model.
Joint PDF Modelling of Turbulent Flow and Dispersion in an Urban Street Canyon

The joint probability density function (PDF) of turbulent velocity and concentration of a passive scalar in an urban street canyon is computed using a newly developed particle-in-cell Monte Carlo method. Compared to moment closures, the PDF methodology provides the full one-point one-time PDF of the underlying fields containing all higher moments and correlations. The small-scale mixing of the scalar released from a concentrated source at the street level is modelled by the interaction by exchange with the conditional mean (IECM) model, with a micro-mixing time scale designed for geometrically complex settings. The boundary layer along no-slip walls (building sides and tops) is fully resolved using an elliptic relaxation technique, which captures the high anisotropy and inhomogeneity of the Reynolds stress tensor in these regions. A less computationally intensive technique based on wall functions to represent the boundary layers and its effect on the solution are also explored. The calculated statistics are compared to experimental data and large-eddy simulation. The present work can be considered as the first example of computation of the full joint PDF of velocity and a transported passive scalar in an urban setting. The methodology proves successful in providing high level statistical information on the turbulence and pollutant concentration fields in complex urban scenarios.
Compliance Bias and Environmental (In)Justice

Scholarship on race- and class-based disparities in regulatory outcomes has failed to provide a theoretically grounded account of this bias’ origin. We address this shortcoming by providing a microlevel explanation of how demographics influence compliance bias or the failure to detect noncompliant firms. We argue that regulatory compliance is best understood as a dual-agent—firm and regulatory officer—production function, and that community mobilization and agency decision-making authority shape bureaucrats’ incentives to report noncompliance. We test our argument with an original dataset on community mobilization and agency structure that delineates the political costs and benefits of state regulatory officers implementing the U.S. Clean Air Act. Using detection-controlled estimation, we find that while certain communities are vulnerable to compliance bias, such bias is mitigated in the presence of either politically mobilized communities or decentralized enforcement authority within the implementing agency.
Strongly Semihereditary Rings and Rings with Dimension

The existence of a well-behaved dimension of a finite von Neumann algebra (see Luck, J Reine Angew Math 495:135–162, 1998) has lead to the study of such a dimension of finite Baer *-rings (see Vas, J Algebra 289(2):614–639, 2005) that satisfy certain *-ring axioms (used in Berberian, 1972). This dimension is closely related to the equivalence relation $ {\sim^{\raisebox{-.1ex}[0pc][0pc]{\scriptsize{*}}}}$ on projections defined by $p{\sim^{\raisebox{-.1ex}[0pc][0pc]{\scriptsize{*}}}} q$ iff p = xx * and q = x * x for some x. However, the equivalence ${\sim^{{\raisebox{.3ex}[0pc][0pc]{\scriptsize\em{a}}}}}$ on projections (or, in general, idempotents) defined by $p{\sim^{{\raisebox{.3ex}[0pc][0pc]{\scriptsize\em{a}}}}} q$ iff p = xy and q = yx for some x and y, can also be relevant. There were attempts to unify the two approaches (see Berberian, preprint, 1988)). In this work, our agenda is three-fold: (1) We study assumptions on a ring with involution that guarantee the existence of a well-behaved dimension defined for any general equivalence relation on projections ~. (2) By interpreting ~ as ${\sim^{{\raisebox{.3ex}[0pc][0pc]{\scriptsize\em{a}}}}},$ we prove the existence of a well-behaved dimension of strongly semihereditary *-rings with positive definite involution. This class is wider than the class of finite Baer *-rings with dimension considered in the past: it includes some non Rickart *-rings. Moreover, none of the *-ring axioms from Berberian (1972) and Vas (J Algebra 289(2):614–639, 2005) are assumed. (3) As the first corollary of (2), we obtain dimension of noetherian Leavitt path algebras over positive definite fields. Secondly, we obtain dimension of a Baer *-ring R satisfying the first seven axioms from Vas (J Algebra 289(2):614–639, 2005) (in particular, dimension of finite AW *-algebras). Assuming the eight axiom as well, R has dimension for ${\sim^{\raisebox{-.1ex}[0pc][0pc]{\scriptsize{*}}}}$ also and the two dimensions coincide. While establishing (2), we obtain some additional results for a right strongly semihereditary ring R: we prove that every finitely generated R-module M splits as a direct sum of a finitely generated projective module and a singular module; we describe right strongly semihereditary rings in terms of relations between their maximal and total rings of quotients; and we characterize extending Leavitt path algebras over finite graphs.
Reflections on the Relationship Between Psychiatric Genetics and Psychiatric Nosology

Research advances in psychiatric genetics have raised expectations that genetic findings might lead to major breakthroughs in psychiatric nosology. The author reviews the plausibility of these claims. Four areas are addressed. First, it is argued that familial aggregation of a single putative psychiatric syndrome provides at best limited evidence for the validity of that syndrome. Second, both traditional and molecular genetic strategies can supply important insights into major diagnostic conundrums. However, evidence that one or a few individual genes impact on risk for two disorders is not likely to resolve definitively the nosologic relationship between the two syndromes. Third, while gene-based essentialist models for psychiatric disorders are conceptually appealing, they are not well supported empirically. Gene discovery in psychiatry is, on its own, unlikely to allow us to "carve nature at its joints," thereby validating categorical psychiatric diagnoses. Fourth, the project to ground "messy" psychiatric categories on the firm foundation of genes-as an archetypal natural kind-may be fundamentally flawed because the very concept of "the gene" as a discrete entity is itself increasingly in doubt. Whereas psychiatric genetics has and will continue to provide important insights into the etiology of psychiatric and substance use disorders, it is not likely alone to provide deep answers to the complex and multifaceted problems facing psychiatric nosology.
Stereocontrolled Syntheses of Tetralone- and Naphthyl-Type Lignans by a One-Pot Oxidative [3,3] Rearrangement/Friedel–Crafts Arylation†

The development of a stereoselective one-pot oxidative [3,3] sigmatropic rearrangement/Friedel–Crafts arylation that provides enantioenriched benzhydryl compounds is reported. The utility of this new transformation is demonstrated by the concise synthesis of several tetralone- and naphthyl-type lignan natural products, many of which display anti-malarial activity.
A Neural Network Approach to Multi-Vehicle Navigation

We develop a neural network formulation for multi-vehicle navigation on a two-dimensional surface. here. A time-linking map is generated for each individual vehicle using techniques similar to the known shortest path algorithms for an isolated vehicle. Neural networks are then applied to generate non-conflicting paths minimizing the time of travel.
Effects of Pulsing on a Vortex Generator Jet

The evolution of a pulsed vortex generator jet embedded in a turbulent boundary layer was examined experimentally. The jet, which was pitched 45 deg and skewed 90 deg, had a velocity three times greater than the freestream. The velocity e eld in planes normal to the freestream was measured by the particle-image-velocimetry method at four stations downstream of the jet exit. The pulsed jet created a starting vortex ring followed by a pair of counter-rotating streamwise vortices, one of them being markedly stronger. Phase-averaged data indicate that the maximum circulation and peak vorticity of the stronger vortex are approximately 30% greater than the average values for a steady jet with the same velocity. However, circulation averaged over the entire pulse was less than that fora steady jet at the samelocation. Thecoreof theprimary streamwisevortex penetratesapproximately 50% farther into the boundary layer than a steady jet with the same velocity. The larger penetration takes place during the initial portion of the pulse and is caused by the jet starting vortex ring.
HYDROGEN IONS, TITRATION AND THE BUFFER INDEX OF BACTERIOLOGICAL MEDIA

The titration of bacteriological media should not be regarded as a crude method of determining the reaction of media, but a process which reveals facts not disclosed by a simple hydrogen ion determ...
Modification of a Macromechanical Finite Element–Based Model for Impact Analysis of Triaxially Braided Composites

Abstract A macro level finite element-based model has been developed to simulate the mechanical and impact response of triaxially-braided polymer matrix composites. In the analytical model, the triaxial braid architecture is simulated by using four parallel shell elements, each of which is modeled as a laminated composite. For the current analytical approach, each shell element is considered to be a smeared homogeneous material. The commercial transient dynamic finite element code LS-DYNA is used to conduct the simulations, and a continuum damage mechanics model internal to LS-DYNA is used as the material constitutive model. The constitutive model requires stiffness and strength properties of an equivalent unidirectional composite. Simplified micromechanics methods are used to determine the equivalent stiffness properties, and results from coupon level tests on the braided composite are utilized to back out the required strength properties. Simulations of quasi-static coupon tests of several representative braided composites are conducted to demonstrate the correlation of the model. Impact simulations of a represented braided composites are conducted to demonstrate the capability of the model to predict the penetration velocity and damage patterns obtained experimentally.
TWO POPULATIONS AND MODELS OF GAMMA-RAY BURSTS

Gamma-ray burst statistics are best explained by a source population at cosmological distances, while spectroscopy and intensity histories of some individual bursts imply an origin on Galactic neutron stars. To resolve this inconsistency I suggest the presence of two populations, one at cosmological distances and the other Galactic. I build on ideas of Shemi and Piran (1990) and of Rees and Mesozaros (1992) involving the interaction of fireball debris with surrounding clouds to explain the observed intensity histories in bursts at cosmological distances. The distances to the Galactic population are undetermined because they are too few to affect the statistics of intensity and direction; I explain them as resulting from magnetic reconnection in neutron star magnetospheres. An appendix describes the late evolution of the debris as a relativistic blast wave.
Individual Differences in Insular Sensitivity During Loss Anticipation Predict Avoidance Learning

The anterior insula has been implicated in both the experience and the anticipation of negative outcomes. Although individual differences in insular sensitivity have been associated with self-report measures of chronic anxiety, previous research has not examined whether individual differences in insular sensitivity predict learning to avoid aversive stimuli. In the present study, insular sensitivity was assessed as participants anticipated monetary losses while undergoing functional magnetic resonance imaging. We found that insular responsiveness to anticipated losses predicted participants' ability to learn to avoid losses (but not to approach gains) in a behavioral test several months later. These findings suggest that in addition to correlating with self-reported anxiety, heightened insular sensitivity may promote learning to avoid loss.
Operational Test Results of a Prototype Superconducting Power Transmission System and Their Extrapolation to the Performance of a Large System

Superconducting cables have electrical characteristics which are similar to overhead lines in many ways. They will be suitable for long-distance circuits of relatively high power and are not similar or competitive with conventional underground cables and their usual applications. The testing of a prototype superconducting power transmission system has progressed to those of an operational nature such as unattended life tests, emergency ratings and simulated failure of the cooling system. The results are used to calculate the performance of a transmission system comprising 2 circuits in a route 100 miles long with a 1000 MVA rating. In addition the measured performance is compared with systems studies made during the development phase.
Half a World: Regional Inequality in Five Great Federations

The paper studies regional (spatial) inequality in the five most populous countries in the world: China, India, the United States, Indonesia, and Brazil in the period 1980-2000. They are all federations or quasi-federations composed of entities with substantial economic autonomy. Two types of regional inequalities are considered: Concept 1 inequality, which is inequality between mean incomes (GDP per capita) of states/provinces, and Concept 2 inequality, which is inequality between population-weighted regional mean incomes. The first inequality speaks to the issue of regional convergence, the second, to the issue of overall inequality as perceived by citizens within a nation. All three Asian countries show rising inequality in terms of both concepts in the 1990s. Divergence in income outcomes is particularly noticeable for the most populous states/provinces in China and India. The United States, where regional inequality is the least, shows further convergence. Brazil, with the highest level of regional inequality, displays no trend. A regression analysis fails to establish robust association between the usual macroeconomic variables and the two types of regional inequality.
A convenient modification of the Gassman oxindole synthesis

Abstract A modification of the Gassman oxindole synthesis is described that proceeds from anilines and ethyl (methylsulfinyl)acetate, using oxalyl chloride to activate the sulfoxide to facilitate the formation of the key N - S bonded intermediate. This procedure is particularly convenient for reactions carried out on smaller scales and for anilines that are susceptible to electrophilic halogenation.
Maximum likelihood geometry in the presence of data zeros

Given a statistical model, the maximum likelihood degree is the number of complex solutions to the likelihood equations for generic data. We consider discrete algebraic statistical models and study the solutions to the likelihood equations when the data contain zeros and are no longer generic. Focusing on sampling and model zeros, we show that, in these cases, the solutions to the likelihood equations are contained in a previously studied variety, the likelihood correspondence. The number of these solutions give a lower bound on the ML degree, and the problem of finding critical points to the likelihood function can be partitioned into smaller and computationally easier problems involving sampling and model zeros. We use this technique to compute a lower bound on the ML degree for 2 x 2 x 2 x 2 tensors of border rank ≤ 2 and 3 x n tables of rank ≤ 2 for n = 11, 12, 13, 14, the first four values of n for which the ML degree was previously unknown.
Casimir interaction among heavy fermions in the BCS-BEC crossover

We investigate a two-species Fermi gas with a large mass ratio interacting by an interspecies short-range interaction. Using the Born-Oppenheimer approximation, we determine the interaction energy of two heavy fermions immersed in the Fermi sea of light fermions as a function of the $s$-wave scattering length. In the BCS limit, we recover the perturbative calculation of the effective interaction between heavy fermions. The $p$-wave projection of the effective interaction is attractive in the BCS limit while it turns out to be repulsive near the unitarity limit. We find that the $p$-wave attraction reaches its maximum between the BCS and unitarity limits, where the maximal $p$-wave pairing of heavy minority fermions is expected. We also investigate the case where the heavy fermions are confined in two dimensions and the $p$-wave attraction between them is found to be stronger than that in three dimensions.
Keiretsu, Governance, and Learning: Case Studies in Change from the Japanese Automotive Industry

Thekeiretsu structuring of assembler-supplier relations historically enabled Japanese auto assemblers to remain lean and flexible while enjoying a level of control over supply akin to that of vertical integration. Yet currently there is much talk of breakdowns inkeiretsu networks. This paper examines some recent developments in Japanese parts-supplykeiretsu.We argue thatkeiretsu relationships are drifting from "hybrid" or "network" (i.e.,keiretsu) governance modes toward the extremes of arms-length contracting and top-down administration. These changes are best understood through a combination of transaction cost and learning perspectives on alliance. Consistent with transaction-cost economics, the shift in purchase-supply relationships can be traced to changes in the nature of parts transactions andkeiretsu-governance structures. A learning perspective on alliance complements and extends transaction-cost theory, providing additional explanation of the sources of change and the specific governance choices being made.Our first two cases document a drift in Toyota'skeiretsu supply network toward a hierarchical form in the management of parts-supply transactions. Toyota has effectively internalized its transactions with Daihatsu by taking a controlling interest. Toyota's strategy toward long-term partner Denso, on the other hand, was very different. Toyota built, from the ground up, an in-house capability in electronic components, thus scaling down its dependence on Denso. A third case considers a general trend in the Japanese auto industry toward greater standardization of parts. With the routinization of quality, reliability, and speed in supply management, the need forkeiretsu-style governance has declined. The withering ofkeiretsu obligations is also traceable to globalization and the continuing weakness of the Japanese economy, which have prompted Japanese firms to question received business practice.
From RosettaNet PIPs to BPEL processes: A three level approach for business protocols

Business protocols in n-party interactions often require centralized protocol design but decentralized execution without the intervention of the designing party. In this paper, we tackle the problem for RosettaNet PIPs by creating a BPEL solution. We do so using a three-level approach, based on BPEL, for defining such protocols: templating for high-level patterns, specialization for particular protocols, and implementation for particular realizations of a protocol.
Functionalization of Guanosine and 2′‐Deoxyguanosine at C6: A Modified Appel Process and SNAr Displacement of Imidazole

Treatment of sugar‐protected 2‐N‐trityl derivatives of guanosine and 2′‐deoxyguanosine with imidazole/triphenylphosphine/iodine/ethyldiisopropylamine gives the corresponding 6‐(imidazol‐1‐yl)‐2‐(tritylamino)purine nucleosides. SNAr displacement of the imidazole moiety with nucleophiles provides 2‐amino‐6‐substituted‐purine nucleosides and 2′‐deoxynucleosides. †In honor and celebration of the 70th birthday of Professor Leroy B. Townsend. #This paper is: Nucleic Acid Related Compounds, 122. Paper 121 is Ref. 1.
Consumption Externalities, Production Externalities and Indeterminacy

In this paper we show that consumption externalities reduce the degree of increasing returns needed to generate indeterminacy in a two-sector optimal growth model. In equilibrium, consumption externalities operate as if the utility function is (close to) linear. If these externalities are strong, the minimum necessary increasing returns approach zero. Therefore, this paper—in a stylized fashion—provides an example of how microbehavior, i.e. interactions at the household level, can generate aggregate instability. Consumption externalities also help to eliminate the counterfactual cyclical behavior of consumption in the two-sector model.
Using hardware multithreading to overcome broadcast/reduction latency in an associative SIMD processor

The latency of broadcast/reduction operations has a significant impact on the performance of SIMD processors. This is especially true for associative programs, which make extensive use of global search operations. Previously, we developed a prototype associative SIMD processor that uses hardware multithreading to overcome the broadcast/reduction latency. In this paper we show, through simulations of the processor running an associative program, that hardware multithreading is able to improve performance by increasing system utilization, even for processors with hundreds or thousands of processing elements. However, the choice of thread scheduling policy used by the hardware is critical in determining the actual utilization achieved. We consider three thread scheduling policies and show that a thread scheduler that avoids issuing threads that will stall due to pipeline dependencies or thread synchronization operations is able to maintain system utilization independent of the number of threads.
Wind-Loading Definition for the Structural Design of Wind-Turbine Generators

The stochastic nature of atmospheric wind must be considered in the design of a wind-turbine generator and the supporting structure. This paper is concerned with the identification of important statistical parameters of fluctuating wind such as turbulence intensity, power spectral density, and coherence functions. This information also provides an insight into the importance of turbulence characteristics for the practical design of wind-turbine generators and is used as a guide for obtaining representative wind-flow measurements in an area of Southern California currently being developed for large-scale wind-energy generation. For the practical design of windturbine generators, short-term extreme-wind-loading descriptions for the stressing of structural systems and long-term loading for the fatigue analysis are discussed in time and frequency domains.
Interlaminar Stresses in Laminated Cylindrical Shells of Composite Materials

Many existing analysis methods for laminated composite material structural components assume structural integrity between laminae and predict load carrying capabilities considerably higher than those sometimes obtained experimentally. These methods do not include the means to determine accurately the interlaminar shear and normal stresses, which can cause premature structural failure. Methods of analysis are presented herein for a laminated circular cylindrical shell composed of generally orthotropic materials subjected to arbitrary axially symmetric loadings. Elastic shell theory, including transverse shear deformation, is utilized. By treating each lamina individually, in conjunction with imposing stress and displacement boundary conditions between laminae, the governing equations for the individual laminae are combined, yielding the interlaminar shear and normal stresses as explicit dependent variables. A parametric study for a generally othotropic circular cylindrical shell, subjected to a uniform pressure with both clamped and simple supported end boundary conditions is presented. Variables include laminate geometry, fiber orientation, stacking sequence and material properties. The solutions obtained provide insight into the interlaminar stress fields of shells with any number of plies, and provide a baseline for finite element and finite difference solutions for the same problem. A computer program has been formulated to expedite calculations with the analytical solution.
Deregulation and Risk

The recent market turmoil has brought attention to how deregulation of the financial sector may affect risk. The purpose of our study is to examine the market's perception of risk associated with deregulation. We accomplish this by decomposing security risk around deregulation into systematic and unsystematic risk. We examine deregulation of several industries and find a consistent pattern of risk adjustment to deregulation, whereby the increase in security risk is temporary and largely unsystematic.