cssi/SciSciGPT-SciSciNet huggingface dataset:
Choosing between Order‐of‐Entry Assumptions in Empirical Entry Models: Evidence from Competition between Burger King and McDonald's Restaurant Outlets

We demonstrate how a non-nested statistical test developed by Vuong (1989) can be used to assess the suitability of alternate order-of-entry assumptions used for identification purposes in empirical entry models. As an example, we estimate an entry model of McDonald’s and Burger King restaurant outlets in United States. The data set focuses on relatively small “isolated” markets. For these markets, the non-nested tests suggest that order-of-entry assumptions that give Burger King outlets a first-mover advantage are statistically preferred. Last, a Monte Carlo experiment provides encouraging results suggesting that the Vuong-type test yields reliable results within the entry model framework.
Hash function learning via codewords

In this paper we introduce a novel hash learning framework that has two main distinguishing features, when compared to past approaches. First, it utilizes codewords in the Hamming space as ancillary means to accomplish its hash learning task. These codewords, which are inferred from the data, attempt to capture similarity aspects of the data's hash codes. Secondly and more importantly, the same framework is capable of addressing supervised, unsupervised and, even, semi-supervised hash learning tasks in a natural manner. A series of comparative experiments focused on content-based image retrieval highlights its performance advantages.
The discourse of requests: Assessment of a politeness approach.

A corpus of transcribed, oral requests used in a previous study of compliance-gaining strategies (Tracy, Craig, Smith, & Spisak, 1984) is examined interpretively from the perspective of the politeness theory of Brown and Levinson (1978). Findings include the following: (1) politeness strategies occur in great abundance and variety; (2) superstrategies are mixed in varyingly skillful ways; (3) goals are accomplished through multifunctional discourse; (4) the interpretation of politeness strategies confronts several kinds of indeterminacy; (5) facework strategies that fall outside the scope of the politeness theory, including aggravation and speaker-oriented strategies, are much in evidence. In response to the several theoretical problems that emerge in the course of the analysis, six tenets on which to build a new theory of facework are proposed.
An Equivalence of Scalar Curvatures on Hermitian Manifolds

For a Kahler metric, the Riemannian scalar curvature is equal to twice the Chern scalar curvature. The question we address here is whether this equivalence can hold for a non-Kahler Hermitian metric. For such metrics, if they exist, the Chern scalar curvature would have the same geometric meaning as the Riemannian scalar curvature. Recently, Liu–Yang showed that if this equivalence of scalar curvatures holds even in average over a compact Hermitian manifold, then the metric must in fact be Kahler. However, we prove that a certain class of non-compact complex manifolds do admit Hermitian metrics for which this equivalence holds. Subsequently, the question of to what extent the behavior of said metrics can be dictated is addressed and a classification theorem is proved.
Understanding Counterexamples with explain

The counterexamples produced by model checkers are often lengthy and difficult to understand. In practical verification, showing the existence of a (potential) bug is not enough: the error must be understood, determined to not be a result of faulty specification or assumptions, and, finally, located and corrected. The explain tool uses distance metrics on program executions to provide automated assistance in understanding and localizing errors in ANSI-C programs. explain is integrated with CBMC, a bounded model checker for the C language, and features a GUI front-end that presents error explanations to the user.
The synthesis of heteroleptic phosphines.

Heteroleptic phosphines (R2PR1) are a class of essential ligands for inorganic and organometallic chemistry. However, the syntheses of these phosphines are often fraught with laborious synthetic hurdles. Consequently, a renewed interest in innovative synthetic methods to access heteroleptic phosphines is emerging. This Perspective presents an overview of modern synthetic approaches to heteroleptic phosphines as well as a discussion of the strengths and limitations of these synthetic methods. A major emphasis is placed on simple and direct routes to phosphines and significant synthetic innovations for P–C bond-forming reactions.
Doubles and negatives are positive (in self-assembly)

In the abstract Tile Assembly Model (aTAM), the phenomenon of cooperation occurs when the attachment of a new tile to a growing assembly requires it to bind to more than one tile already in the assembly. Often referred to as "temperature-2" systems, those which employ cooperation are known to be quite powerful (i.e. they are computationally universal and can build an enormous variety of shapes and structures). Conversely, aTAM systems which do not enforce cooperative behavior, a.k.a. "temperature-1" systems, are conjectured to be relatively very weak, likely to be unable to perform complex computations or algorithmically direct the process of self-assembly. Nonetheless, a variety of models based on slight modifications to the aTAM have been developed in which temperature-1 systems are in fact capable of Turing universal computation through a restricted notion of cooperation. Despite that power, though, several of those models have previously been proven to be unable to perform or simulate the stronger form of cooperation exhibited by temperature-2 aTAM systems. In this paper, we first prove that another model in which temperature-1 systems are computationally universal, namely the restricted glue TAM (rgTAM) in which tiles are allowed to have edges which exhibit repulsive forces, is also unable to simulate the strongly cooperative behavior of the temperature-2 aTAM. We then show that by combining the properties of two such models, the Dupled Tile Assembly Model (DTAM) and the rgTAM into the DrgTAM, we derive a model which is actually more powerful at temperature-1 than the aTAM at temperature-2. Specifically, the DrgTAM, at temperature-1, can simulate any aTAM system of any temperature, and it also contains systems which cannot be simulated by any system in the aTAM.
Phonon mechanism in the most dilute superconductor n-type SrTiO3

Superconductivity of n-doped SrTiO3, which remained enigmatic for half a century, is treated as a particular case of nonadiabatic phonon pairing. Motivated by experiment, we suggest the existence of the mobility edge at some dopant concentration. The itinerant part of the spectrum consists of three conduction bands filling by electrons successively. Each subband contributes to the superconducting instability and exhibits a gap in its energy spectrum at low temperatures. We argue that superconductivity of n-doped SrTiO3 results from the interaction of electrons with several longitudinal (LO) optical phonons with frequencies much larger than the Fermi energy. Immobile charges under the mobility edge threshold increase the “optical” dielectric constant far above that in clean SrTiO3 placing control on the electron–LO phonon interaction. TC initially grows as density of states at the Fermi surface increases with doping, but the accumulating charges reduce the electrons–polar-phonon interaction by screening the longitudinal electric fields. The theory predicts maxima in the TC-concentration dependence indeed observed experimentally. Having reached a maximum in the third band, the transition temperature finally decreases, rounding out the TC (n) dome, the three maxima with accompanying superconducting gaps emerging consecutively as electrons fill successive bands. This arises from attributes of the LO optical phonon pairing of electrons. The mechanism of LO phonons opens the path to increasing superconducting transition temperature in bulk transition-metal oxides and other polar crystals, and in charged 2D layers at the LaAaO3/SrTiO3 interfaces and on the SrTiO3 substrates.
A modified simple shooting method for solving two-point boundary-value problems

Abstract : In the study of mechanics and optimal control, one often encounters what is called a two-point boundary-value problem (TPBVP). A couple of methods exist for solving these problems, such as the Simple Shooting Method (SSM) and its variation, the Multiple Shooting Method (MSM). In this paper a new method is proposed that was designed from the favorable aspects of both the SSM and the MSM. The Modified Simple Shooting Method (MSSM) sheds undesirable aspects of both previously mentioned methods to yield a superior, faster method for solving TPBVPs. The convergence of the MSSM is proven under mild conditions on the TPBVP. A comparison of the MSM and the MSSM is made for a problem where both methods converge. We also provide a second example where the MSM fails to converge while the MSSM converges rapidly.
Self‐Regulation and Learning

Self-regulation (self-regulated learning) refers to learning that results from students' self-generated thoughts and behaviors that are systematically oriented toward their learning goals. Various theories are explained that have been proposed to account for self-regulation including operant, information processing, developmental, social constructivist, and social cognitive. Common features of theories include an emphasis on learner activity, cyclical nature of self-regulation, and motivation to instigate and sustain self-regulation. Research investigations are summarized that identified key self-regulatory processes used by students to help them learn and explore the operation of these processes during learning. Some important self-regulatory processes are goal setting, self-evaluation of progress, learning strategies, metacognition, self-construction of theories, and self-efficacy. Research shows that self-regulatory processes influence learners' achievement cognitions, behaviors, and emotions. Two interventions are summarized that sought to enhance learners' self-regulation and learning in different contexts. Recommendations are given for self-regulation research in the areas of human development, curricular integration, cultural differences, and learning with technology. Keywords: self-regulation; self-efficacy; metacognition; learning strategies; motivation
Hydrostatic equilibrium profiles for gas in elliptical galaxies

We present an analytic formulation for the equilibrium gas density profile of early-type galaxies that explicitly includes the contribution of stars in the gravitational potential. We build a realistic model for an isolated elliptical galaxy and explore the equilibrium gas configurations as a function of multiple parameters. For an assumed central gas temperature k B T 0 = 0.6 keV, we find that neglecting the gravitational effects of stars, which can contribute substantially in the innermost regions, leads to an underestimate of the enclosed baryonic gas mass by up to ~65 per cent at the effective radius and by up to ~15 per cent at the Navarro-Frenk-White (NFW) scale radius, depending on the stellar baryon fraction. This formula is therefore important for estimating the baryon fraction in an unbiased fashion. These new hydrostatic equilibrium solutions, derived for the isothermal and polytropic cases, can also be used to generate more realistic initial conditions for simulations of elliptical galaxies. Moreover, the new formulation is relevant when interpreting X-ray data. We compare our composite isothermal model to the standard β-model used to fit X-ray observations of early-type galaxies, to determine the value of the NFW scale radius r s . Assuming a 10 per cent stellar baryon fraction, we find that the exclusion of stars from the gravitational potential leads to (i) an underestimate of r s by ~80 per cent and (ii) an overestimate of the enclosed dark matter at r s by a factor of ~2, compared to the equivalent β-model fit results when stars are not taken into account. For higher stellar mass fractions, a β-model is unable to accurately reproduce our solution, indicating that when the observed surface brightness profile of an isolated elliptical galaxy is found to be well fitted by a β-model, the stellar mass fraction cannot be much greater than ~10 per cent.
Compressed constraints in probabilistic logic and their revision

In probabilistic logic entailments, even moderate size problems can yield linear constraint systems with so many variables that exact methods are impractical. This difficulty can be remedied in many cases of interest by introducing a three-valued logic (true, false, and "don't care"). The three-valued approach allows the construction of "compressed" constraint systems which have the same solution sets as their two-valued counterparts, but which may involve dramatically fewer variables. Techniques to calculate point estimates for the posterior probabilities of entailed sentences are discussed.
On the Modeling and Simulation of Reaction-Transfer Dynamics in Semiconductor-Electrolyte Solar Cells

The mathematical modeling and numerical simulation of semiconductor-electrolyte systems play important roles in the design of high-performance semiconductor-liquid junction solar cells. In this work, we propose a macroscopic mathematical model, a system of nonlinear partial differential equations, for the complete description of charge transfer dynamics in such systems. The model consists of a reaction-drift-diffusion-Poisson system that models the transport of electrons and holes in the semiconductor region and an equivalent system that describes the transport of reductants and oxidants, as well as other charged species, in the electrolyte region. The coupling between the semiconductor and the electrolyte is modeled through a set of interfacial reaction and current balance conditions. We present some numerical simulations to illustrate the quantitative behavior of the semiconductor-electrolyte system in both dark and illuminated environments. We show numerically that one can replace the electrolyte region in the system with a Schottky contact only when the bulk reductant-oxidant pair density is extremely high. Otherwise, such replacement gives significantly inaccurate description of the real dynamics of the semiconductor-electrolyte system.
A dual role for NOTCH signaling in joint cartilage maintenance and osteoarthritis

Loss of NOTCH signaling in postnatal murine joints results in osteoarthritis, indicating a requirement for NOTCH during maintenance of joint cartilage. However, NOTCH signaling components are substantially increased in abundance in posttraumatic osteoarthritis in humans and mice, suggesting either a reparative or a pathological role for NOTCH activation in osteoarthritis. We investigated a potential dual role for NOTCH in joint maintenance and osteoarthritis by generating two mouse models overexpressing the NOTCH1 intracellular domain (NICD) within postnatal joint cartilage. The first mouse model exhibited sustained NOTCH activation to resemble pathological NOTCH signaling, whereas the second model had transient NOTCH activation, which more closely reflected physiological NOTCH signaling. Sustained NOTCH signaling in joint cartilage led to an early and progressive osteoarthritic-like pathology, whereas transient NOTCH activation enhanced the synthesis of cartilage matrix and promoted joint maintenance under normal physiological conditions. Through RNA-sequencing, immunohistochemical, and biochemical approaches, we identified several targets that could be responsible for NOTCH-mediated cartilage degradation, fibrosis, and osteoarthritis progression. These targets included components of the interleukin-6 (IL-6)-signal transducer and activator of transcription 3 (STAT3) and mitogen-activated protein kinase signaling pathways, which may also contribute to the posttraumatic development of osteoarthritis. Together, these data suggest a dual role for the NOTCH pathway in joint cartilage, and they identify downstream effectors of NOTCH signaling as potential targets for disease-modifying osteoarthritis drugs.
Relational memory in psychotic bipolar disorder

Sheffield JM, Williams LE, Cohen N, Heckers S. Relational memory in psychotic bipolar disorder. Bipolar Disord 2012: 14: 537–546. © 2012 The Authors. Journal compilation © 2012 John Wiley & Sons A/S. Objectives: Recent research has highlighted the phenotypic and genetic overlap of bipolar disorder and schizophrenia. Cognitive deficits in bipolar disorder parallel those seen in schizophrenia, particularly for bipolar disorder patients with a history of psychotic features. Here we explored whether relational memory deficits, which are prominent in schizophrenia, are also present in patients with psychotic bipolar disorder. Methods: We tested 25 patients with psychotic bipolar disorder on a relational memory paradigm previously employed to quantify deficits in schizophrenia. During the training, participants learned to associate a set of faces and background scenes. During the testing, participants viewed a single background overlaid by three trained faces and were asked to recall the matching face, which was either present (Match trials) or absent (Non-Match trials). Explicit recognition and eye-movement data were collected and compared to those for 28 schizophrenia patients and 27 healthy subjects from a previously published dataset. Results: Contrary to our prediction, we found psychotic bipolar disorder patients were less impaired in relational memory than schizophrenia subjects. Bipolar disorder subjects showed eye-movement behavior similar to healthy controls, whereas schizophrenia subjects were impaired relative to both groups. However, bipolar disorder patients with current delusions and/or hallucinations were more impaired than bipolar disorder patients not currently experiencing these symptoms. Conclusions: We found that patients with psychotic bipolar disorder had better relational memory performance than schizophrenia patients, indicating that a history of psychotic symptoms does not lead to a significant relational memory deficit.
Pigment gallstone disease

Black and brown pigment gallstones are morphologically, compositionally, and clinically distinct. Black stones form primarily in the gallbladder in sterile bile and are associated with advanced age, chronic hemolysis, alcoholism, cirrhosis, pancreatitis, and total parenteral nutrition. Brown stones form not only within the gallbladder but also within the intrahepatic and extrahepatic ducts; they are uniformly infected with enteric bacteria and are usually associated with ascending cholangitis. Brown stones are related to juxtapapillary duodenal diverticula and are the predominant type of de novo common bile duct stones. Cholecystectomy is usually curative in black pigment stone disease, whereas stones often recur after cholecystectomy for brown stone disease. The pathogenesis of black stones is probably related to nonbacterial, nonenzymatic hydrolysis of bilirubin conjugates. At the pH of bile, this results in two monohydrogenated bilirubin anions that precipitate with calcium ions. Bilirubin monoconjugates that are increased in several conditions, such as Gilbert's syndrome and chronic hemolysis, may play a pivotal role in black stone formation as a source of unconjugated monohydrogenated bilirubin and as a possible co-precipitant with calcium. The precipitation of calcium carbonate and phosphate is influenced by local gallbladder factors. Brown pigment stones are formed in bile infected with enteric bacteria that elaborate hydrolytic enzymes: beta-glucuronidase, phospholipase A, and conjugated bile acid hydrolase. The resulting anions of bilirubin and fatty acids form insoluble calcium salts. We used nb/nb mice with a chronic hemolytic anemia as a model of hemolysis-induced black stone disease. The presence of 40% bilirubin monoconjugates in mouse gallstones indicated the importance of this moiety in the pathogenesis of black stones. Other data obtained by marrow transplantation experiments in mice revealed the relative importance of genotype versus the hemolytic anemia on determinants such as biliary bile acid composition and mucin secretory glands in the mouse gallbladder neck. Additional physical chemical studies of the interaction of unconjugated bilirubin in model bile solutions will be helpful in further delineating the pathogenesis of both black and brown pigment gallstones.
A combinatorial curvature flow for compact 3-manifolds with boundary

We introduce a combinatorial curvature flow for PL metrics on compact triangulated 3-manifolds with boundary consisting of surfaces of negative Euler characteristic. The flow tends to find the complete hyperbolic metric with totally geodesic boundary on a manifold. Some of the basic properties of the combinatorial flow are established. The most important ones is that the evolution of the PL curvature satisfies a combinatorial heat equation. It implies that the total curvature decreases along the flow. The local convergence of the flow to the hyperbolic metric is also established if the triangulation is isotopic to a totally geodesic triangulation.
A Simple Two-Parameter Characterization of Gamma-Ray Burst Time Histories

A simple scheme delineates long GRBs with similar time histories using the internal luminosity function (ILF) power-law index and the spectral lag. Two generalizations are made about time history morphologies: (1) GRBs with long spectral lags contain fewer pulses that are broader than those found in bursts with short spectral lags, and (2) short-lag bursts with small ILF power-law indices have many narrow pulses and are highly variable, while long-lag bursts with small ILF power-law indices are characterized by broad, smooth pulses and have low variability. GRB time-history morphologies primarily identify intrinsic rather than extrinsic characteristics based on correlations with gamma-ray luminosity, afterglow luminosity, and number of pulses. These characteristics result because internal relativistic effects, due to bulk Lorentz factor, are larger than cosmological effects, and because the numbers and shapes of pulses indicate different efficiencies and forms of GRB energy release. Single-pulsed GRBs are characterized by either large ILF power indices (indicating a range of jet-opening angles and Lorentz factors with a FRED pulse shape), or long lags (large jet-opening angles with low Lorentz factors with either a FRED pulse shape or an unpeaked, smooth pulse shape). They also have lower luminosity afterglows than multipulsed GRBs. GRBs with simple time histories are often associated with Type Ibc supernovae. This suggests that some single-pulsed GRBs contain single, beamed blast waves that are similar to and have characteristics that overlap with those of many supernovae. Such a connection may not exist between multipulsed GRBs and supernovae.
Synthetic studies on tetrazomine: Stereochemical assignment of the β-hydroxypipecolic acid

Abstract The asymmetric syntheses of 2(R), 3(R)- and 2(S), 3(S)-β-hydroxypipecolic acids are described, including the determination of the absolute stereochemistry of the β-hydroxypipecolic acid moiety of tetrazomine.
Application of ion-scattering spectroscopy to catalyst characterization

Abstract The study of surfaces has evolved in the last decade from a virtually dormant field to one that is vibrant with new ideas and technologies. In the past, the only useful information to be gained from surface techniques was physical in nature, i.e., surface area determination, pore size distributions, film thickness, and surface roughness. No chemical information could be obtained. Today, with the advent of spectroscopic methods, it is possible to gather a variety of information regarding the chemical nature of the surface. Examples of such information include oxidation state determinations, structural effects, and elemental and atomic analysis.
Nickel(0)-catalyzed asymmetric hydrocyanation of 1,3-dienes.

1,2-Bis-diarylphosphinites are excellent ligands for the Ni(0)-catalyzed hydrocyanation of certain types of 1,3-dienes. 1-Phenyl-1,3-butadiene, 1-vinyl-3,4-dihydronaphthalene, and 1-vinylindene undergo highly regioselective hydrocyanation under ambient conditions to give exclusively the 1,2-adducts in good to excellent yields. Using bis-1,2-diarylphosphinites derived from d-glucose, the highest enantioselectivities to-date for asymmetric hydrocyanation of 1,3-dienes (70−83% ee's) have been obtained.
The magnetic fields of classical T tauri stars

We report new magnetic field measurements for 14 classical T Tauri stars (CTTSs). We combine these data with one previous field determination in order to compare our observed field strengths with the field strengths predicted by magnetospheric accretion models. We use literature data on the stellar mass, radius, rotation period, and disk accretion rate to predict the field strength that should be present on each of our stars according to these magnetospheric accretion models. We show that our measured field values do not correlate with the field strengths predicted by simple magnetospheric accretion theory. We also use our field strength measurements and literature X-ray luminosity data to test a recent relationship expressing X-ray luminosity as a function of surface magnetic flux derived from various solar feature and main-sequence star measurements. We find that the T Tauri stars we have observed have weaker than expected X-ray emission by over an order of magnitude on average using this relationship. We suggest the cause for this is actually a result of the very strong fields on these stars, which decreases the efficiency with which gas motions in the photosphere can tangle magnetic flux tubes in the corona.
Closed form analysis of squirrel cage induction motors with anisotropic modeling of stator and rotor

Summary form only given. The paper presents a closed form solution of Maxwell's equations in squirrel cage induction motors. The solution is obtained for a cylindrical multi-layer geometry. The squirrel cage is represented by an equivalent anisotropic homogeneous medium. The effect of stator slots and teeth is included by a second anisotropic homogeneous medium. The induction motor is modeled as six concentric cylindrical layers representing the different construction components of the motor. The governing partial differential equations are solved for the excitation source, conducting and non-conducting regions. The obtained formulas allow for efficient calculations of machine performance which may help the motor designer to select the proper parameters of the machine that fit the design requirements. Accuracy of the method is verified against finite element simulations, a commercial motor design program and experimental results.
Characteristic potentials for mesoscopic rings threaded by an Aharonov-Bohm flux

Electro-static potentials for samples with the topology of a ring and penetrated by an Aharonov-Bohm flux are discussed. The sensitivity of the electron-density distribution to small variations in the flux generates an effective electro-static potential which is itself a periodic function of flux. We investigate a simple model in which the flux sensitive potential leads to a persistent current which is enhanced compared to that of a loop of non-interacting electrons. For sample geometries with contacts the sensitivity of the electro-static potential to flux leads to a flux-induced capacitance. This capacitance gives the variation in charge due to an increment in flux. The flux-induced capacitance is contrasted with the electro-chemical capacitance which gives the variation in charge due to an increment in an electro-chemical potential. The discussion is formulated in terms of characteristic functions which give the variation of the electro-static potential in the interior of the conductor due to an increment in the external control parameters (flux, electro-chemical potentials).
Site selectivity in the rhodium(II)-catalyzed reaction of α-diazoimides. Ligand and substituent effects

Abstract The product distribution obtained from Rh(II)-catalyzed decomposition of α-diazoimides derived from glycine methyl ester has been found to be selectively controlled by the proper choice of catalyst. When the reaction was carried out using perfluorinated ligands, the diazoimide cyclized to produce an isomunchnone dipole whose formation could be monitored by NMR spectroscopy. Reaction of the dipole with a trapping agent such as N-phenylmaleimide resulted in the isolation of a 1,3-dipolar cycloadduct in high yield. The product distribution changed dramatically when rhodium(II)-acetate was employed as the catalyst. The products obtained from this reaction were derived from an azabicyclic epoxide intermediate. The catalyst effect can be modulated by the addition of Sc(OTf)3 as a Lewis acid or by using nitromethane as the solvent. Changing the nature of the interacting carbonyl group had little effect on the cyclization pathways.
Characterization of Kalman filter residuals in the presence of mismodeling

The mean and covariance of a Kalman filter residual are computed for specific cases in which the Kalman filter model differs from a linear model that accurately represents the true system (the truth model). Multiple model adaptive estimation (MMAE) uses a bank of Kalman filters, each with a different internal model, and a hypothesis testing algorithm that uses the residuals from this bank of Kalman filters to estimate the true system model. At most, only one Kalman filter model will exactly match the truth model and will produce a residual whose mean and standard deviation have already been analyzed. All of the other filters use internal models that mismodel the true system. We compute the effects of a mismodeled input matrix, output matrix, and state transition matrix on these residuals. The computed mean and covariance are compared with simulation results of flight control failures that correspond to mismodeled input matrices and output matrices.
Photoredox activation and anion binding catalysis in the dual catalytic enantioselective synthesis of β-amino esters

The enantioselective oxidative C–H functionalization of tetrahydroisoquinoline derivatives is achieved through the merger of photoredox and asymmetric anion-binding catalysis. This combination of two distinct catalysis concepts introduces a potentially general approach to asymmetric transformations in oxidative photocatalysis.
Has the border narrowed

Abstract In the late 1980s Canada’s provinces traded 20 times more with one another than with US states of comparable size and distance. In other words, the Canada-US border exerted a strong effect on the pattern of Canada’s continental trade patterns. However the formation of the Canada-US Free Trade Area could have reduced the impact of the border on bilateral trade. Surprisingly, estimates from a gravity model of aggregate Canadian trade reveal no evidence of a significant, sustained fall in the border effect between 1988 and 1996.
Electrodeposition of In‐Se, Cu‐Se, and Cu‐In‐Se Thin Films

Indium-selenium, copper-selenium, and copper-indium-selenium thin films have been prepared by electrodeposition techniques on molybdenum substrates. Electrodeposited precursors are prepared at varying potentials, pH, and deposition times. The adhesion and uniformity of indium selenide on molybdenum substrates are improved by electrodepositing an initial copper layer (500 {angstrom}) on molybdenum. The films (In-Se, Cu-Se, and Cu-In-Se) are annealed at 250 and 450 C in Ar for 15 min and are slow-cooled (3 C/min). The films are characterized by electron microprobe analysis, inductive-coupled plasma spectrometry, X-ray diffraction analysis, Auger electron spectroscopy, and scanning electron microscopy. The as-deposited precursor films are loaded in a physical evaporation chamber and addition In or Cu and Se are added to the film to adjust the final composition to CuInSe{sub 2}. The device fabricated using electrodeposited Cu-In-Se precursor layers resulted in a solar cell efficiency of 9.4%.
Revealing New Physical Structures in the Supernova Remnant N63A through Chandra Imaging Spectroscopy

We present Chandra X-ray observations of the supernova remnant (SNR) N63A in the Large Magellanic Cloud (LMC). N63A, one of the brightest LMC remnants, is embedded in an H II region and is probably associated with an OB association. The optical remnant consists of three lobes of emission contained within the approximately 3 times larger X-ray remnant. Our Chandra data reveal a number of new physical structures in N63A. The most striking of these are the several "crescent"-shaped structures located beyond the main shell that resemble similar features seen in the Vela SNR. In Vela, these have been interpreted as arising from high-speed clumps of supernova ejecta interacting with the ambient medium. Another distinct feature of the remnant is a roughly triangular "hole" in the X-ray emission near the location of the optical lobes and the brightest radio emission. X-ray spectral analysis shows that this deficit of emission is the result of absorption by an intervening dense cloud with a mass of ~450 M☉ that is currently being engulfed by the remnant's blast wave. We also find that the rim of the remnant, as well as the crescent-shaped features, has considerably softer X-ray spectra than the interior. Limits on hard X-ray emission rule out a young, energetic pulsar in N63A, but the presence of an older or less active one, powering a wind nebula with a luminosity less than ~4 × 1034 ergs s-1, is allowed.
The Case Against Linking Environmental Degradation And National Security

This chapter aims to link environmental degradation and national security and it explores three claims. First, it is analytically misleading to think of environmental degradation as a national security threat, because the traditional focus of national security—interstate violence—has little in common with either environmental problems or solutions. Second, the effort to harness the emotive power of nationalism to help mobilize environmental awareness and action may prove counterproductive by undermining globalist political sensibility. Third, environmental degradation which is not very likely to cause interstate wars. The wide-ranging contemporary conceptual ferment in the language used to understand and act upon environmental problems is therefore both a natural and an encouraging development. Military violence and environmental degradation are linked directly in at least three major ways. First, pursuit of national-security-from-violence through military means consumes resources that could be spent on environmental restoration. Second, war is directly destructive of the environment. Third, preparation for war causes pollution and consumes significant quantities of resources.
Contracting endomorphisms and Gorenstein modules

A finite module M over a noetherian local ring R is said to be Gorenstein if Exti(k, M) = 0 for all i ≠ dim R. An endomorphism φ: R → R of rings is called contracting if \(\varphi^i(\mathfrak{m}) \subseteq \mathfrak{m}^2\) for some i ≥ 1. Letting φR denote the R-module R with action induced by φ, we prove: A finite R-module M is Gorenstein if and only if HomR(φR, M) ≅ M and ExtiR(φR, M) = 0 for 1 ≤ i ≤ depth R.
A scheduling algorithm for replicated real-time tasks

An algorithm for scheduling real-time periodic tasks on a multiprocessor system under a fault-tolerant requirement is presented. The approach incorporates both the redundancy and masking technique, and the imprecise computation model. Since the tasks in hard real-time systems have stringent timing constraints, the redundancy and masking technique is more appropriate than the rollback techniques, which usually require extra time for error recovery. The imprecise computation model provides flexible functionality by trading off the quality of the result produced by a task with the amount of processing time required to produce it. It therefore permits the performance of a real-time system to degrade gracefully. The algorithm was evaluated by stochastic analysis and Monte Carlo simulations. The results showed that the algorithm was resilient under hardware failure. >
Quantum lower bounds by quantum arguments

We propose a new method for proving lower bounds on quantum query algorithms. Instead of a classical adversary that runs the algorithm with on input and then modifies the input, we use a quantum adversary that runs the algorithm with a superposition of inputs. If the algorithm works correctly, its state becomes entangled with the superposition over inputs. We bound the number of queries needed to achieve a sufficient entanglement and this implies a lower bound on the number of queries for the computation. Using this method, we prove two new Ω(√N) lower bounds on computing AND of ORs and inverting a permutation and also provide more uniform proofs for several known lower bounds which have been previously proven via a variety of different techniques.
Enantioselective Total Synthesis of Some Brevicomins Using Aldolase Antibody 38C2

Aldolase antibody 38C2 (Aldrich no. 47,995-0) catalyzes the aldol reaction between hydroxyacetone and aldehyde 7 to give dihydroxyketone 8a in an enantiomeric excess (ee) > 99 %. This reaction has been performed on a semi- preparative scale to give the product in 55 % yield (eea 98 %). Aldol 8a can be converted to hydroxybrevicomins ent-5 and ent-6 by reduction and acid-catalyzed cyclization. Antibody 38C2 also catalyzes the retro-aldol reaction of racemic syn-8. After 52 % conversion, the enantiomeric product (8b) is obtained in > 99 % ee .B y using either antibody-catalyzed aldol or retro-aldol reactions, both aldol enantiomers can be prepared with a single antibody catalyst. This methodology has been applied in highly enantioselective total syntheses of ten brevicomins.
High-Temperature Transport Properties of the Zintl Phases Yb11GaSb9 and Yb11InSb9†

Two rare-earth Zintl phases, Yb_(11)GaSb_9 and Yb_(11)InSb_9, were synthesized in high-temperature self-fluxes of molten Ga and In, respectively. Structures were characterized by both single-crystal X-ray diffraction and powder X-ray diffraction and are consistent with the published orthorhombic structure, with the space group Iba2. High-temperature differential scanning calorimetry (DSC) and thermal gravimetry (TG) measurements reveal thermal stability to 1300 K. Seebeck coefficient and resistivity measurements to 1000 K are consistent with the hypothesis that Yb_(11)GaSb_9 and Yb_(11)InSb_9 are small band gap semiconductors or semimetals. Low doping levels lead to bipolar conduction at high temperature, preventing a detailed analysis of the transport properties. Thermal diffusivity measurements yield particularly low lattice thermal conductivity values, less than 0.6 W/m K for both compounds. The low lattice thermal conductivity suggests that Yb_(11)MSb_9 (M = Ga, In) has the potential for high thermoelectric efficiency at high temperature if charge-carrier doping can be controlled.
On estimation across analog erasure links with and without acknowledgements

Consider the problem of estimating a linear timeinvariant process across communication links that erase data stochastically. We compare the stability and performance for two protocols: when the sensor transmits new data only on obtaining an acknowledgement for previously transmitted data (so-called Transmission Control Protocol (TCP)-like protocols) and when the source transmits new data at every time step (socalled User Datagram Protocol (UDP)-like protocols). We show that the effect of acknowledgements and retransmissions on performance is case dependent. When a single sensor transmits data across a single link, we prove that TCP-like protocols always perform worse than UDP-like protocols in the sense of minimizing error covariance. When either multiple sensors or multiple links are present, we prove that TCP-like protocols may perform better than the UDP-like protocols.
Dependency, democracy, and infant mortality: a quantitative, cross-national analysis of less developed countries

This study presents quantitative, sociological models designed to account for cross-national variation in infant mortality rates. We consider variables linked to four different theoretical perspectives: the economic modernization, social modernization, political modernization, and dependency perspectives. The study is based on a panel regression analysis of a sample of 59 developing countries. Our preliminary analysis based on additive models replicates prior studies to the extent that we find that indicators linked to economic and social modernization have beneficial effects on infant mortality. We also find support for hypotheses derived from the dependency perspective suggesting that multinational corporate penetration fosters higher levels of infant mortality. Subsequent analysis incorporating interaction effects suggest that the level of political democracy conditions the effects of dependency relationships based upon exports, investments from multinational corporations, and international lending institutions. Transnational economic linkages associated with exports, multinational corporations, and international lending institutions adversely affect infant mortality more strongly at lower levels of democracy than at higher levels of democracy: intranational, political factors interact with the international, economic forces to affect infant mortality. We conclude with some brief policy recommendations and suggestions for the direction of future research.
On Interference Networks Over Finite Fields

We present a framework to study linear deterministic interference networks over finite fields. Unlike the popular linear deterministic models introduced to study Gaussian networks, we consider networks where the channel coefficients are general scalars over some extension held F(p m ) (scalar mth extension held models), m x m diagonal matrices over F p (m-symbol extension ground held models), and m x m general nonsingular matrices (multiple-input and multiple-output (MIMO) ground held models). We use the companion matrix representation of the extension held to convert mth extension scalar models into MIMO ground held models, where the channel matrices have special algebraic structure. For such models, we consider the 2×2×2 topology (two-hop two-flow) and the three-user interference network topology. We derive achievability results and feasibility conditions for certain schemes based on the precoding-based network alignment (PBNA) approach, where intermediate nodes use random linear network coding (i.e., propagate random linear combinations of their incoming messages) and nontrivial precoding/decoding is performed only at the network edges, at the sources and destinations. Furthermore, we apply this approach to the scalar 2 × 2 × 2 complex Gaussian interference channel with fixed channel coefficients and show two competitive schemes outperforming other known approaches at any SNR, where we combine finite field linear precoding/decoding with lattice coding and the compute and forward approach at the signal level. As a side result, we also show significant advantages of vector linear network coding both in terms of feasibility probability (with random coding coefficients) and in terms of coding latency, with respect to standard scalar linear network coding, in PBNA schemes.
Export Sector Dynamics and Domestic Growth: The Case of Colombia

Analyses of Colombian data have generally failed to confirm the hypothesis of export-led growth. This paper generates several measures of export diversification and structural change in exports, and argues that these measures are useful in assessing growth externalities generated by the export sector. In a simultaneous-equations framework, increases in the rate of export structural change are associated with accelerated Colombian GDP growth. Export diversification, by contrast, is not a source of economic growth, and the reduced-form relationship between aggregate lagged export growth and GDP growth is weak.
Predictor-Corrector Entry Guidance for Low-Lifting Vehicles

This paper investigates a numerical predictor-corrector methodology for adaptive and accurate entry guidance for vehicles with low lift-to-drag ratios, such as the Orion Crew Exploration Vehicle. The central ingredient in this approach is bank-angle parameterization. The choice of the bank-angle profile representation determines how the guidance problem will be solved, as well as the efficiency, performance, and robustness of the algorithm. Two popular forms of bank-angle parameterization, one in longitudinal mode and the other in three-dimensional mode, are closely examined. Special new robustification features are designed in the bank-angle parameterization that are shown to noticeably increase the overall performance of the algorithm. With the use of the predictor-corrector entry guidance approach, an interesting characteristic of the entry trajectory of a low-lifting vehicle is identified that reveals a definitive trend between the initial bank-angle magnitude and the peak load factor. Based on this observation, a simple and effective predictive load-relief strategy is developed for low-lifting vehicles. Extensive dispersion simulations are conducted to evaluate and verify the design features of the algorithm. The testing shows that the robustified longitudinal mode of the predictor-corrector entry guidance algorithm consistently offers very satisfactory performance even in highly dispersed cases. Such an algorithm holds distinct potential for onboard applications.
Comparison of IRI-2001 with TOPEX TEC measurements

During the last decade, the TOPEX/Poseidon mission has provided a wealth of data pertaining to total electron content (TEC) measurements over the oceans, where conventional measurements are sparse. In this study, a comprehensive comparison of the TOPEX TEC measurements with the recent version of the International Reference Ionosphere (IRI-2001) was performed. The study covered solar cycle, seasonal, geomagnetic activity, and longitudinal variations. First, it was found that both the IRI and TOPEX TEC show a negligibly small geomagnetic dependency, regardless of the solar activity and seasonal conditions. For solar activity, however, not only the TECs from the IRI and TOPEX measurements, but also the difference between them, strongly depend on the solar activity. The comparison also shows that the daytime low-latitude ionosphere from the IRI always develops earlier than the corresponding TOPEX measurements, appearing as an overestimate of IRI TEC at around 7 magnetic local time (MLT) in the morning. With respect to the annual and seasonal variations of TEC, the TOPEX TEC shows stronger annual and semiannual anomalies than the IRI TEC both at low latitudes and at upper mid-latitudes. However, the IRI and TOPEX TECs show a similar seasonal anomaly only for high solar activity. Finally, the longitudinal variations of the IRI TEC show good agreement with the TOPEX measurements for low solar activity, but for high solar activity, large discrepancies occur in the Pacific sector.
Axiomatic derivation of scoring rules without the ordering assumption

Earlier derivations of scoring rules, by Smith (1973) and Young (1975), assumed that a voter can express only a rank ordering of the alternatives on his or her ballot. This paper shows that scoring rules can be derived without this ordering assumption. It is shown that a voting rule must be a scoring rule if it satisfies three basic axioms: reinforcement, overwhelming majorities, and neutrality. Other range and nonreversal axioms are also discussed.