cssi/SciSciGPT-SciSciNet huggingface dataset:
Numerical simulation of high-incidence flow over the F-18 fuselage forebody

As part of the NASA High Alpha Technology Program, fine-grid Navier-Stokes solutions have been obtained for flow over the fuselage forebody and wing leading-edge extension of the F/A-18 High Alpha Research Vehicle at large incidence. The resulting flows are complex and exhibit cross-flow separation from the sides of the forebody and from the leading-edge extension. A well-defined vortex pattern is observed in the leeward-side flow. Results obtained for laminar flow show good agreement with flow visualizations obtained in ground-based experiments. Further, turbulent flows computed at high-Reynolds-number flight-test conditions show good agreement with surface and off-surface visualizations obtained in flight.
Hydrothermal deposition of zirconia coatings on pre-oxidized BWR structural materials

Abstract An in situ hydrothermal deposition process is being developed to apply a thin coating of zirconia onto the structural materials used in Boiling Water Reactors as a potential method for mitigating intergranular stress corrosion cracking. The process has successfully deposited ZrO 2 onto as-received interior surfaces of 304 stainless steel and Alloy 600 tubes [Z.F. Zhou, E. Chalkova, S.N. Lvov, P. Chou, R. Pathania, Corros. Sci. 49 (2007) 830]. This paper discusses the application of the coating on specimens with different surface conditions: as-received; ground to remove the as-received surface; and ground and pre-oxidized. For comparable deposition parameters and for a given substrate, the different surface conditions did not influence the morphology or the thickness of the coating, but had a substantial impact on adhesion. As in our previous study, electrochemical potentials of the coated specimens in simulated BWR environment were not clearly lower than those of uncoated specimens [Zhou et al., 2007].
E+e- cross section and exclusion of massless electroweak gauginos

Abstract Measurements of the total hadronic cross section in e + e − annihilation are shown to be capable of severely limiting the possibility that gauginos have negligible tree level masses. A combined analysis of 1997 and earlier LEP data, considering simultaneously conventional SUSY signatures and purely hadronic final states, should achieve a 95% CL sensitivity to the case that the SU(2) and U(1) gauginos are massless. If integrated luminosity targets are achieved, it should also be possible to exclude the case that the wino or wino and gluino are light while the bino is heavy, except possibly for a small region of μ , tan β . The analysis applies whether or not R-parity is conserved, and can also be used to reduce the model-dependence of conventional SUSY searches.
Remark on some conformally invariant integral equations: the method of moving spheres

where a > 0 is some constant and x ∈ R. Hypothesis (2) was removed by Caffarelli, Gidas and Spruck in [8]; this is important for applications. Such Liouville type theorems have been extended to general conformally invariant fully nonlinear equations by Li and Li ([24]–[27]); see also related works of Viaclovsky ([40]–[41]) and Chang, Gursky and Yang ([13]–[14]). The method used in [21], as well as in much of the above cited work, is the method of moving planes. The method of moving planes has become a very powerful tool in the study of nonlinear elliptic equations; see Aleksandrov [1], Serrin [38], Gidas, Ni and Nirenberg [21]–[22], Berestycki and Nirenberg [2], and others. In [30], Li and Zhu gave a proof of the above mentioned theorem of Caffarelli, Gidas and Spruck using the method of moving spheres (i.e. the method of moving planes together with the conformal invariance), which fully exploits the conformal invariance of the problem and, as a result, captures the solutions directly rather than going through the usual procedure of proving radial symmetry of solutions and then classifying radial solutions. Significant simplifications to the proof in [30] have been made in Li and Zhang [29]. The method of moving spheres has been used in [24]–[27]. Liouville type theorems for various conformally invariant equations have received much attention; see, in addition to the above cited papers, [23], [17], [15], [33], [42] and [43].
Double-negation elimination in some propositional logics

This article answers two questions (posed in the literature), each concerning the guaranteed existence of proofs free of double negation. A proof is free of double negation if none of its deduced steps contains a term of the formn(n(t)) for some term t, where n denotes negation. The first question asks for conditions on the hypotheses that, if satisfied, guarantee the existence of a double-negation-free proof when the conclusion is free of double negation. The second question asks about the existence of an axiom system for classical propositional calculus whose use, for theorems with a conclusion free of double negation, guarantees the existence of a double-negation-free proof. After giving conditions that answer the first question, we answer the second question by focusing on the Lukasiewicz three-axiom system. We then extend our studies to infinite-valued sentential calculus and to intuitionistic logic and generalize the notion of being double-negation free. The double-negation proofs of interest rely exclusively on the inference rule condensed detachment, a rule that combines modus ponens with an appropriately general rule of substitution. The automated reasoning program Otter played an indispensable role in this study.
Rotational hysteresis of exchange-spring magnets

We highlight our experimental studies and micromagnetic simulations of the rotational hysteresis in exchange-spring magnets. Magneto-optical imaging and torque magnetometry measurements for Sm–Co/Fe exchange-spring films with uniaxial in-plane anisotropy show that the magnetization rotation created in the magnetically soft Fe layer by a rotating magnetic field is hysteretic. The rotational hysteresis is due to the reversal of the chirality of the spin spiral structure. Micromagnetic simulations reveal two reversal modes of the chirality, one at low fields due to an in-plane untwisting of the spiral, and the other, at high fields, due to an out-of-plane fanning of the spiral.
Two-loop QED corrections to Bhabha scattering

We obtain a simple relation between massless and massive scattering amplitudes in gauge theories in the limit where all kinematic invariants are large compared to particle masses. We use this relation to derive the two-loop QED corrections to large-angle Bhabha scattering.
Lower Bounds for Dimensions of Sums of Sets

We study lower bounds for the Minkowski and Hausdorff dimensions of the algebraic sum E+K of two sets E,K⊂ℝ d .
A further result on global stabilization of oscillators with bounded delayed input

This note revisits the problem of globally stabilizing an oscillator with a bounded delayed input. It establishes that an oscillator with input saturation can be globally asymptotically stabilized by a linear state feedback even in the presence of an arbitrarily large delay in the input. This result strengthens a recent result in the literature, which shows that such an oscillator can be globally asymptotically stabilized with a sufficiently small control input and the magnitude of the control input goes to zero as the delay increases to infinity. The controller constructed in this note thus improves the efficiency of the closed-loop system by fully utilizing the actuator capacity.
Thickness-dependent radiative properties of Y-Ba-Cu-O thin films

Some applications of high-temperature superconductors where their radiative behavior is important, such as bolometers, optically triggered switches and gates, and space-cooled electronics, require the superconductor to be in the form of a very thin film whose radiative properties cannot be adequately represented by a semi-infinite analysis. Two properties of particular importance are the film absorptance and the combined film/substrate absorptance, which are crucial to the operation of many devices. Here, calculations of the spectral, normal-incidence absorptance of superconducting-state Y-Ba-Cu-O films on MgO substrates suggest that a decrease in the film thickness often leads to an increase in both the film and the film/substrate absorptance. Furthermore, both can exhibit a maximum at some optimal value of film thickness. Room-temperature experiments verify the qualitative features of the spectral film/substrate absorptance, indicating the assumption that the film is a smooth, continuous slab with a refractive index equal to that of well-aligned bulk Y-Ba-Cu-O is valid, at least in the normal state and for films as then as 35 nm.
A Topological Menagerie

Some of the party games that young teenagers play have surprisingly rich mathemati cal content. "Entanglement" is one such game in which couples are linked with strings tied tightly to their wrists, as shown in Figure la, and then challenged to disentangle themselves, often leading to Figure lb. In fact there is a quick solution (needless to say missing the point of the game): simply push a bit of the girl's string under the boy's at his wrist, pass the resulting loop over his hand, and then pull it free on the other side, as shown in Figure 2. One way to formulate this mathematically is to ask for an isotopy to remove the meridian loop m from a rigid wire w embedded in the 3-sphere, as shown in Figure 3a. (The wire represents the boy with his attached string, where the upper loop of the wire is his right hand, while the meridian represents the girl with her string.) Of course this is easy: just slide m along w to a point just below the upper loop of w, and then stretch it out and pull it off the top. Or put differently, observe that w is isotopic to the trivial wire o-o and so the meridian slips right off.
The Charm quark on the lattice

Abstract We formulate lattice fermions in a way that encompasses Wilson fermions as well as the static and non-relativistic approximations. In particular, we treat m q α systematically ( m q is the fermion mass) showing show how to understand the Wilson action as an effective action for systems with p ⪡ m q . The results show how to extract matrix elements and the spectrum from simulations with m q a ≈ 1, which is relevant for the charm quark.
The one-loop five-graviton scattering amplitude and its low-energy limit

A covariant path-integral calculation of the even-spin structure contribution to the one-loop N-graviton scattering amplitude in the type-II superstring theory is presented. The apparent divergence of the N = 5 amplitude is resolved by separating it into twelve independent terms corresponding to different orders of inserting the graviton vertex operators. Each term is well defined in an appropriate kinematic region and can be analytically continued to physical regions where it develops branch cuts required by unitarity. The zero-slope limit of the N = 5 amplitude is performed, and the Feynman diagram content of the low-energy field theory is examined. Both one-particle irreducible (1PI) and one-particle reducible (1PR) graphs with massless internal states are generated in this limit. One set of 1PI graphs has the same divergent dependence on the cut-off as that found in the four-graviton case, and it is proved that such graphs exist for all N. The 1PR graphs are contributed by the poles in the world-sheet chiral Green functions.
Solar magnetic fields and the dynamo theory

Abstract Unlike Earth’s dipolar magnetic fields, solar magnetic fields consist of wide ranges of length-scales and strengths, and interestingly, they evolve in a cyclic fashion with a 22-year periodicity. A magnetohydrodynamic dynamo operating in the Sun is most likely responsible for producing the solar magnetic activity cycle. While the first solar dynamo models were built half a century ago, recent views differ significantly from those models. According to widely accepted present concepts, the large-scale solar dynamo is of flux-transport type, which involves three basic processes: (i) generation of toroidal fields by shearing the pre-existing poloidal fields by differential rotation (the Ω-effect); (ii) re-generation of poloidal fields by lifting and twisting the toroidal fluxtubes (the α-effect); (iii) flux transport by meridional circulation. This class of dynamos has been successful in explaining many large-scale solar cycle features, including a particularly difficult one – the correct phase relationship between the equatorward-migrating sunspot belt and the poleward drifting large-scale, diffuse fields. The dynamo cycle period in such models is primarily governed by the meridional flow speed near the bottom of the convection zone. After briefly reviewing the historical background, we will present the successes of flux-transport dynamos, including their predictive capability. For example, we will demonstrate how the meridional circulation plays a key role in governing the Sun’s memory about its own magnetic field, and how a flux-transport dynamo-based predictive tool can explain the cause of the very slow polar reversal in the so-called “peculiar” cycle 23 compared to those in cycles 20, 21 and 22. We will close by presenting explanations for certain long-term variability using these models, such as, what may have maintained the observed cyclic variation in slow solar wind flow during Maunder minima, in the presence of near zero solar activity.
Highly Selective Catalytic Intermolecular Reductive Coupling of Alkynes and Aldehydes

Alkynes (internal and terminal) and aldehydes (aromatic and aliphatic) are reductively coupled in a single catalytic reaction to yield di- and trisubstituted allylic alcohols with high stereoselectivity and regioselectivity. In most cases, a 1:1 ratio of alkyne to aldehyde is sufficient for efficient coupling. The yield and regioselectivity are strongly dependent on the phosphine ligand, but the allylic alcohols formed are invariably the products of cis addition to the alkyne.
Iridium-Catalyzed C–H Borylation of Cyclopropanes

The borylation of cyclopropanes catalyzed by the combination of (η6-mes)IrBpin3 or [Ir(COD)OMe]2 and a phenanthroline derivative is reported. The borylation occurs selectively at the methylene C–H bonds of the cyclopropane ring over methine or methyl C–H bonds. High diasteroselectivities were observed from reactions catalyzed by the combination of iridium and 2,9-Me2phenanthroline. The cyclopropylboronate esters that are generated are versatile synthetic intermediates that can be converted to trifluoroborate salts, boronic acids, cyclopropylarenes, cyclopropylamines, and cyclopropanols.
Efficient distributed locality sensitive hashing

Distributed frameworks are gaining increasingly widespread use in applications that process large amounts of data. One important example application is large scale similarity search, for which Locality Sensitive Hashing (LSH) has emerged as the method of choice, specially when the data is high-dimensional. To guarantee high search quality, the LSH scheme needs a rather large number of hash tables. This entails a large space requirement, and in the distributed setting, with each query requiring a network call per hash bucket look up, also a big network load. Panigrahy's Entropy LSH scheme significantly reduces the space requirement but does not help with (and in fact worsens) the search network efficiency. In this paper, focusing on the Euclidian space under ι2 norm and building up on Entropy LSH, we propose the distributed Layered LSH scheme, and prove that it exponentially decreases the network cost, while maintaining a good load balance between different machines. Our experiments also verify that our theoretical results.
A Highly Selective and General Palladium Catalyst for the Oxidative Heck Reaction of Electronically Nonbiased Olefins

A general, highly selective oxidative Heck reaction is reported. The reaction is high-yielding under mild conditions without the need for base or high temperatures, and the selectivity is excellent, without the requirement for electronically biased olefins or other specific directing groups. A preliminary mechanistic investigation suggests that the unusually high selectivity may be due to the catalyst’s sensitivity to C−H bond strength in the selectivity-determining β-hydride elimination step.
The bivariate beta distribution: comparison of Monte Carlo generators and evaluation of parameter estimates

The bivariate and multivariate beta distributions may provide appropriate stochastic models for a number of processes, particularly those involving random proportions. Researchers may therefore find it necessary to estimate the parameters of such distributions or generate Monte Carlo samples with known parameter values. Two possible generating technique for beta bivariates are presented and compared in this paper. Estimating equations for the three parameters of the bivariate beta distribution are presented. These use the method of moments, the only tractable estimating techniques and an analysis of their properties is also presented.This paper focuses on the bivariate beta distribution, but a user of a higher-dimensioned beta model will be able to make use of the discussion herein to provide assistance in determining many of the properties of such a model.
The omega-6/omega-3 ratio and cardiovascular disease risk: Uses and abuses

The cardioprotective effects of omega-3 (n-3) fatty acids (FAs) are well known, but the role that the n-6 FAs play in coronary heart disease is unclear. These two classes of essential FAs compete for a number of enzyme systems, and their metabolites can powerfully influence (often in different directions) inflammatory responses, vascular reactivity, and platelet aggregation. Accordingly, the n-6/n-3 FA ratio may be of value in interpreting biomarker data and in making nutritional recommendations. Although initially appealing, there are few human experimental and clinical trial data to support this view. This paper reviews a variety of studies that, in the aggregate, suggest that the ratio is, both on theoretical and evidential grounds, of little value. Metrics that include the n-3 FAs alone, especially eicosapentaenoic and docosahexaenoic acids, appear to hold the greatest promise.
Preparer versus user introductory sequence: the impact on performance in Intermediate Accounting I

Abstract The normal subject matter in the first semester of a traditional introductory accounting course closely parallels the content in Intermediate Accounting I. Because research shows that student performance in college accounting courses is influenced by prerequisite courses, one would expect that those who take a user-approach introductory sequence will not perform as well in later courses. The research reported in this paper compares the performance of students in a traditional Intermediate Accounting I course who took either a preparer-or-user approach introductory sequence. Of the 150 accounting majors in the sample, 53 (97) took a user-approach (preparer-approach) introductory sequence. Of the 97 preparer-approach students, 47 (50) were four-year (transfer) students. The results are consistent with prior research and indicate that SAT scores and student effort are significant for each of the individual tests and for the overall average in course examinations. Gender is not consistent a factor in performance, which also supports prior research. The data indicate that students who took a preparer-approach sequence did not score higher in Intermediate Accounting I and that entry status is not a factor in this performance. This finding leads to the question of whether or not a user-approach would better service those students in our introductory accounting courses who are not accounting majors.
Can high-velocity stars reveal black holes in globular clusters?

We estimate the number of individual fast-moving stars observable in globular clusters under the assumption that the clusters contain massive central black holes that follow the galactic MBH-σ relationship. We find that radial velocity measurements are unlikely to detect such stars but that proper-motion studies could reveal such stars, if they exist, in the most likely clusters. Thus, Hubble Space Telescope proper-motion studies can test this hypothesis in a few nearby clusters.
Job creation and housing construction: Constraints on metropolitan area employment growth☆

Abstract Differences in the supply of housing generate substantial variation in house prices across the United States. Because house prices influence migration, the elasticity of housing supply also has an important impact on local labor markets. I assemble evidence on housing supply regulations and examine their effect on metropolitan area housing and labor market dynamics. Locations with relatively few barriers to construction experience more residential construction and smaller increases in house prices in response to an increase in housing demand. Furthermore, housing supply constraints alter local employment and wage dynamics in locations where the degree of regulation is most severe.
Reputational Dynamics and Political Careers

I study a model of repeated elections with both symmetric learning about candidate ability and moral hazard. In this model, candidates choose how to allocate their resources between constituency service and policy work. Early in their careers, they devote excessive time to constituency service in an attempt to manipulate voter learning. Since voters use elections to select better candidates, incumbents become more confident of reelection over time and reduce the distortion in their effort allocations. I embed the basic model in a common agency framework to study seniority norms in legislative organization. The model organizes many of the stylized facts about elections and congressional organization, including retrospective voting, the incumbency advantage, the dynamics of effort allocation over a career, the importance of constituency service, and seniority norms in committee assignments. Copyright 2005, Oxford University Press.
Evolution of Strategies to Prepare Synthetic Mimics of Carboxylate-Bridged Diiron Protein Active Sites

We present a comprehensive review of research conducted in our laboratory in pursuit of the long-term goal of reproducing the structures and reactivity of carboxylate-bridged diiron centers used in biology to activate dioxygen for the conversion of hydrocarbons to alcohols and related products. This article describes the evolution of strategies devised to achieve these goals and illustrates the challenges in getting there. Particular emphasis is placed on controlling the geometry and coordination environment of the diiron core, preventing formation of polynuclear iron clusters, maintaining the structural integrity of model complexes during reactions with dioxygen, and tuning the ligand framework to stabilize desired oxygenated diiron species. Studies of the various model systems have improved our understanding of the electronic and physical characteristics of carboxylate-bridged diiron units and their reactivity toward molecular oxygen and organic moieties. The principles and lessons that have emerged from these investigations will guide future efforts to develop more sophisticated diiron protein model complexes.
PKS 1510–089: A Head-on View of a Relativistic Jet

The gamma-ray blazar PKS 1510-089 has a highly superluminal milliarcsecond jet at a position angle (P.A.) of -28° and an arcsecond jet with an initial P.A. of 155°. With a ΔP.A. of 177° between the arcsecond and milliarcsecond jets, PKS 1510-089 is perhaps the most highly misaligned radio jet ever observed and serves as a graphic example of projection effects in a highly beamed relativistic jet. Here we present the results of observations designed to bridge the gap between the milliarcsecond and arcsecond scales. We find that a previously detected "counterfeature" to the arcsecond jet is directly fed by the milliarcsecond jet. This feature is located 03 from the core, corresponding to a deprojected distance of 30 kpc. The feature appears to be dominated by shocked emission and has an almost perfectly ordered magnetic field along its outside edge. We conclude that it is most likely a shocked bend, viewed end-on, where the jet crosses our line of sight to form the southern arcsecond jet. While the bend appears to be nearly 180° when viewed in projection, we estimate the intrinsic bending angle to be between 12° and 24°. The cause of the bend is uncertain; however, we favor a scenario where the jet is bent after it departs the galaxy, either by ram pressure due to winds in the intracluster medium or simply by the density gradient in the transition to the intergalactic medium.
Sequential SmI2-promoted one- and two-electron reactions of carbohydrates

Abstract Highly functionalized and densely oxygenated bicyclic compounds were obtained by treating a modified carbohydrate template with SmI 2 and a ketone or aldehyde which effected a tandem radical cyclization and carbonyl addition reaction.
A meta-analysis of the relationship between endometrial thickness and outcome of in vitro fertilization cycles.

Objective: The objective was to evaluate the relationship between endometrial thickness on the day of human chorionic gonadotropin administration and pregnancy outcome in in vitro fertilization cycles. Design: This was a systematic review and meta-analysis. Materials and Methods: We identified 484 articles using Cochrane library, PubMed, Web of Science, and Embase searches with various key words including endometrial thickness, pregnancy, assisted reproductive technology, endometrial pattern, and in vitro fertilization. A total of 14 studies with data on endometrial thickness and outcome were selected, representing 4922 cycles (2204 pregnant and 2718 nonpregnant). The meta-analysis with a random effects model was performed using comprehensive meta-analysis software. We calculated the standardized mean difference, odds ratio (OR), and 95% confidence intervals (CIs). Results: There was a significant difference in the mean endometrial thickness between pregnant and nonpregnant groups (P<0.001), with a standardized mean difference of 0.4 mm (95% CI 0.22-0.58). The OR for pregnancy was 1.40 (95% CI 1.24-1.58). Conclusions: The mean endometrial thickness was significantly higher in pregnant women compared to nonpregnant. The mean difference between two groups was <1 mm which may not be clinically meaningful. Although there may be a relationship between endometrial thickness and pregnancy, implantation potential is probably more complex than a single ultrasound measurement can determine.
Hemodynamic Effects of Isosorbide Dinitrate vs Nitroglycerin in Patients with Unstable Angina

The hemodynamic response to nitroglycerin administration, to sublingual or oral administration of isosorbide dinitrate, or to a placebo was evaluated and compared in 37 patients with unstable angina pectoris under resting, pain-free conditions. Patients with congestive heart failure were not included in this study. Serial measurements of mean arterial blood pressure (MAP), pulmonary arterial end-diastolic pressure (PAEDP), cardiac index (CI), and heart rate (HR) were obtained for one hour following nitroglycerin administration and for four hours following sublingual or oral administration of isosorbide dinitrate. Echocardiographic end-diastolic volume (EDV) measurements were obtained for the groups receiving isosorbide dinitrate or placebo. There was a significant (P
The Property Tax Incidence Debate and the Mix of State and Local Finance of Local Public Expenditures

Many states in the US have in recent years changed the mix of state and local revenue sources used to finance local public expenditures, especially primary and secondary education, with local property taxes being replaced by various sources of state tax revenue. This article examines the desirability of such a tax substitution, focusing on the implications of the long-standing debate between the 'benefit tax' and 'capital tax' views of the incidence of the tax. It also includes a discussion of some recent research that elaborates the capital tax view of the property tax. (JEL codes: H10, H21, H22, H71) Copyright , Oxford University Press.
Dynamic Growth Estimates of Maximum Vorticity for 3D Incompressible Euler Equations and the SQG Model

By performing estimates on the integral of the absolute value of vorticity along a local vortex line segment, we establish a relatively sharp dynamic growth estimate of maximum vorticity under some assumptions on the local geometric regularity of the vorticity vector. Our analysis applies to both the 3D incompressible Euler equations and the surface quasi-geostrophic model (SQG). As an application of our vorticity growth estimate, we apply our result to the 3D Euler equation with the two anti-parallel vortex tubes initial data considered by Hou-Li [12]. Under some additional assumption on the vorticity field, which seems to be consistent with the computational results of [12], we show that the maximum vorticity can not grow faster than double exponential in time. Our analysis extends the earlier results by Cordoba-Fefferman [6, 7] and Deng-Hou-Yu [8, 9].
Incentive compatible market design with applications

This paper studies markets for heterogeneous goods using mechanism-design theory. For each combination of desirable properties, we derive an assignment process with these properties in the form of a corresponding direct-revelation game, or we show that it does not exist. Each participant’s utility is quasi-linear in money, and depends upon the allocation that he gets and his privately known multidimensional ‘type.’ The key properties are incentive compatibility, individual rationality, efficiency, and budget balance. The main results characterize mechanisms that are ex post incentive compatible in combination with other properties.
Mass extinctions and the sun's encounters with spiral arms

Abstract The terrestrial fossil record shows that the exponential rise in biodiversity since the Precambrian period has been punctuated by large extinctions, at intervals of 40 to 140 Myr. These mass extinctions represent extremes over a background of smaller events and the natural process of species extinction. We point out that the non-terrestrial phenomena proposed to explain these events, such as boloidal impacts (a candidate for the end-Cretaceous extinction) and nearby supernovae, are collectively far more effective during the solar system's traversal of spiral arms. Using the best available data on the location and kinematics of the Galactic spiral structure (including distance scale and kinematic uncertainties), we present evidence that arm crossings provide a viable explanation for the timing of the large extinctions.
Computed Eccentricity Effects on Turbine Rim Seals at Engine Conditions With a Mainstream

A previously verified axisymmetric Navier-Stokes computer code was extended for three-dimensional computation of eccentric rim seals of almost any configuration. All compressibility and thermal/momentum interaction effects are completely included, and the temperature, pressure, and Reynolds number of the mainstream, coolant stream, and turbine wheel are fixed at actual engine conditions. Regardless of the seal eccentricity, both ingress and egress are found between θ = -30 and 100 deg, which encompasses the location of maximum radial clearance at θ = 0 deg. All other θ locations within the rim seal show only egress, as does the concentric base case for all circumferential locations. Further, the maximum ingress occurs near θ = 30 deg for all eccentricities. This is found to produce a blade root/retainer temperature rise from the concentric case of 390 percent at 50 percent eccentricity and a 77 percent rise at 7.5 percent eccentricity. In addition, the nature of an increased eccentricity causing a decreased seal effectiveness is examined, along with the corresponding increase of cavity-averaged temperature.
Granularity issues for solving polynomial systems via globally convergent algorithms on a hypercube

Polynomial systems of equations frequently arise in many applications such as solid modelling, robotics, computer vision, chemistry, chemical engineering, and mechanical engineering. Locally convergent iterative methods such as quasi-Newton methods may diverge or fail to find all meaningful solutions of a polynomial system. Recently a homotopy algorithm has been proposed for polynomial systems that is guaranteed globally convergent (always converges from an arbitrary starting point) with probability one, finds all solutions to the polynomial system, and has a large amount of inherent parallelism. There are several ways the homotopy algorithms can be decomposed to run on a hypercube. The granularity of a decomposition has a profound effect on the performance of the algorithm. The results of decompositions with two different granularities are presented. The experiments were conducted on an iPSC-16 hypercube using actual industrial problems.
Spin-3/2 Ising model for tricritical points in ternary fluid mixtures

We present a lattice-gas model of ternary fluid mixtures. Within the mean-field approximation, we study a nonsymmetric tricritical point in this model. We compare our results to the experimental observations on the system ethanol-water-carbon-dioxide. In the course of our work, we have studied a Landau theory describing the neighborhood of a fourth-order critical point. Also, we have noted that mean-field theory indicates the existence of a fourth-order critical point in the spin-1 model of Blume, Emery, and Griffiths, corresponding to $Kl0$, $J+Kg0$.
Deforming Curves in Jacobians to Non-Jacobians I: Curves in C (2)

We introduce deformation theoretic methods for determining when a curve X in a nonhyperelliptic Jacobian JC will deform with JC to a non-Jacobian. We apply these methods to a particular class of curves in the second symmetric power \(\mathbb{C}^{(2)}\) of C. More precisely, given a pencil \(g_{d}^{1}\) of degree d on C, let X be the curve parametrizing pairs of points in divisors of \(g_{d}^{1}\) (see the paper for the precise scheme-theoretical definition). We prove that if X deforms infinitesimally out of the Jacobian locus with JC then either d=4 or d=5, dim H° \((g_{5}^{1}) = 3\) and C has genus 4
A framework for practical parallel fast matrix multiplication

Matrix multiplication is a fundamental computation in many scientific disciplines. In this paper, we show that novel fast matrix multiplication algorithms can significantly outperform vendor implementations of the classical algorithm and Strassen's fast algorithm on modest problem sizes and shapes. Furthermore, we show that the best choice of fast algorithm depends not only on the size of the matrices but also the shape. We develop a code generation tool to automatically implement multiple sequential and shared-memory parallel variants of each fast algorithm, including our novel parallelization scheme. This allows us to rapidly benchmark over 20 fast algorithms on several problem sizes. Furthermore, we discuss a number of practical implementation issues for these algorithms on shared-memory machines that can direct further research on making fast algorithms practical.
Electron cloud measurements in heavy-ion driver for HEDP and inertial fusion energy

Abstract The high-current experiment (HCX) at LBNL is a driver scale single beam injector that provides a 1 MeV K + ion beam current of 0.18 A for 5 μs. It transports high-current beams with large fill factor (ratio of the maximum beam envelope radius to the beam pipe radius) and low emittance growth that are required to keep the cost of the power plant competitive and to satisfy the target requirements of focusing ion beams to high-power density. Beam interaction with the background gas and walls desorbs electrons that can multiply and accumulate, creating an electron cloud. This ubiquitous effect grows at higher fill factors and degrades the quality of the beam. We review simulations and diagnostics tools used to measure electron production, accumulation and its properties.
Checking Finite Traces Using Alternating Automata

Alternating automata have been commonly used as a basis for static verification of reactive systems. In this paper we show how alternating automata can be used in runtime verification. We present three algorithms to check at runtime whether a reactive program satisfies a temporal specification, expressed by a linear-time temporal logic formula. The three methods start from the same alternating automaton but traverse the automaton in different ways: depth-first, breadth-first, and backwards, respectively. We then show how an extension of these algorithms, that collects statistical data while verifying the execution trace, can be used for a more detailed analysis of the runtime behavior. All three methods have been implemented and experimental results are presented.
LASER LIGHT SCATTERING STUDIES OF BULK POLYMERS IN THE GLASS TRANSITION REGIME

The application of laser light scattering techniques to characterize the structural and dynamical properties of bulk polymers near the glass transition temperature is reviewed. Preliminary results of a study of poly(n-butyl methacrylate) are presented. As in an earlier study of atactic polystyrene, the results suggest the coexistence of two relaxation mechanisms near Tg: a fast, single exponential decay; a slow process characterized by a wide distribution of relaxation times. The slow relaxation mechanism is evidently the main-chain glass transition process; it appears possible that the fast decay is a manifestation of side-chain motion. However, in contrast to the polystyrene system where the fast mechanism is always of small amplitude in the temperature range amenable to study (Tg < T < Tg + 40°), the fast mechanism in the poly(n-butyl methacrylate) system exhibits a sudden transition to high amplitude (∼50 percent of the total observable relaxation amplitude) at T ∼ Tg + 30°. At this point therefore, we suggest that a strong resonant coupling of the fast process with the slow relaxation is occurring.
Deuterium isotope effects in constrained tryptophan derivatives: Implications for tryptophan photophysics

The deuterium isotope effect on the fluorescence quantum yield and lifetime of the constrained tryptophan derivative 3-carboxy-1,2,3,4-tetrahydro-2-carboline, W(1), was determined as a function of pH and temperature. The isotope effect between pH 3.5 and 11 is attributed to a temperature-dependent quenching process common to all indoles. At room temperature the quantum yield ratio in D{sub 2}O and H{sub 2}O is 1.05 for W(1) zwitterion and 1.7 for W(1) anion. The temperature dependence of the fluorescence lifetime was determined for the zwitterion and the anion in H{sub 2}O and D{sub 2}. The frequency factors A and activation energies E{sup *} in H{sub 2}O are A = 6 x 10{sup 16} s{sup -1}, E{sup *} = 12.6 kcal/mol for W(1) anion, and N-methylindole The frequency factors A of these compounds are 2- to 3-fold larger in H{sub 2}O than in D{sub 2}O. The large deuterium isotope effect W(1) anion at room temperature compared to W(1) zwitterion results from two factors: a smaller temperature-independent nonradiative rate and a larger isotopically sensitive temperature-dependent rate. Several mechanisms for the intrinsic deuterium isotope effect are discussed. Two mechanisms are consistent with available data for indoles: {open_quotes}invisible{close_quotes} or incomplete proton transfer from water to indole and formationmore » of a water-indole charge-transfer exciplex. 57 refs., 8 figs., 4 tabs.« less
A New Model of the Galactic Magnetic Field

A new, much-improved model of the Galactic magnetic field (GMF) is presented. We use the WMAP7 Galactic synchrotron emission map and more than 40,000 extragalactic rotation measures to constrain the parameters of the GMF model, which is substantially generalized compared with earlier work to now include an out-of-plane component (as suggested by observations of external galaxies) and striated-random fields (motivated by theoretical considerations). The new model provides a greatly improved fit to observations. Consistent with our earlier analyses, the best-fit model has a disk field and an extended halo field. Our new analysis reveals the presence of a large, out-of-plane component of the GMF; as a result, the polarized synchrotron emission of our Galaxy seen by an edge-on observer is predicted to look intriguingly similar to what has been observed in external edge-on galaxies. We find evidence that the cosmic-ray electron density is significantly larger than given by GALPROP or else that there is a widespread striated component to the GMF.
Packing and Covering Properties of Rank Metric Codes

This paper investigates packing and covering properties of codes with the rank metric. First, we investigate packing properties of rank metric codes. Then, we study sphere covering properties of rank metric codes, derive bounds on their parameters, and investigate their asymptotic covering properties.
Constraining sterile neutrino warm dark matter with Chandra observations of the Andromeda galaxy

We use the Chandra unresolved X-ray emission spectrum from a 12'–28' (2.8–6.4 kpc) annular region of the Andromeda galaxy to constrain the radiative decay of sterile neutrino warm dark matter. By excising the most baryon-dominated, central 2.8 kpc of the galaxy, we reduce the uncertainties in our estimate of the dark matter mass within the field of view and improve the signal-to-noise ratio of prospective sterile neutrino decay signatures relative to hot gas and unresolved stellar emission. Our findings impose the most stringent limit on the sterile neutrino mass to date in the context of the Dodelson-Widrow model, ms < 2.2 keV (95% C.L.). Our results also constrain alternative sterile neutrino production scenarios at very small active-sterile neutrino mixing angles.
A deletion-invariance property for random measures satisfying the Ghirlanda–Guerra identities

Abstract We show that if a discrete random measure on the unit ball of a separable Hilbert space satisfies the Ghirlanda–Guerra identities then by randomly deleting half of the points and renormalizing the weights of the remaining points we obtain the same random measure in distribution up to rotations.
The Secondary Alkaline Zinc Electrode

Zinc is the most commonly used battery electrode, and zinc primary batteries have found numerous applications. The zinc electrode is electrochemically reversible in alkaline electrolytes, and there is a strong incentive to develop a practical secondary battery based on this metal. However, secondary batteries that use zinc electrodes typically exhibit short lifetimes, because of problems with zinc material redistribution and undesirable zinc morphologies that form during recharge. There has been a worldwide effort to develop a long‐lived secondary alkaline zinc electrode, and marked improvements in cell lifetimes have resulted. This article reviews these efforts, paying particular attention to research and development during the period 1975–1990.
The Preparation and Properties of A New Family of Amorphous Fluoropolymers: Teflon® Af

Teflon® AF is a family of amorphous fluoropolymers with glass transition temperatures as high as 300° based on bis-2,2-trfluoromethyl-4,5-difluoro-1,3-dioxole, (I), which has unusual properties [1–3] (Figure 1). The family retains the superior electrical, chemical resistance and thermal properties associated with fluoropolymers. In addition the polymers have high optical clarity, limited solubility in some commercially available perfluorinated ethers such as Fluorinert® FC-75 and improved physical properties below their glass transition temperatures (Figure 2). Teflon® AF polymers may be either solution cast into clear micron thin films or melt processed into a variety of forms.
New synthesis of 2,2-bis(hydroxymethyl) methylenecyclopropane, a key intermediate for antiviral cyclopropavir

Abstract Synthesis of 2,2‐bis(hydroxymethyl)methylenecyclopropane (2) is described. Cyclopropane dicarboxylate 3 was reduced to diol 4, which was acetylated to give diacetate 5. Acetoxy‐bromo elimination afforded methylenecyclopropane 6. Debenzylation gave the title compound 2.
Oxidation of SiC Fiber-Reinforced SiC Matrix Composites with a BN Interphase

The oxidation kinetics of SiC fiber-reinforced SiC matrix composites with a BN interphase (SiC/BN/SiC) and the constituent fibers was characterized by thermogravimetric analysis and microstructural characterization at temperatures (816-1538°C) and oxygen partial pressures (0.1% to 5% O2) relevant to the hypersonic flight and re-entry environments. TGA of the SiC fibers showed that oxidation of the thin BN surface layer led to initially rapid oxidation kinetics and formation of a relatively thick silica scale at very short times under most test conditions. At longer times the fiber oxidation kinetics were representative of silica formation on pure SiC. Oxidation of the composites was conducted on coupons with the SiC seal coat removed on one edge to simulate damage to the composite, allowing ingress of oxygen to the fiber tows. Microscopy was conducted to determine the distance of oxygen ingress into the coupon. At the lower temperatures and oxygen partial pressures the exposed edge did not seal off by silica formation, yet the BN interphase areas were only minimally oxidized. At the intermediate temperatures silica formed at the exposed surface limiting further oxidation of the exposed fibers and BN interphase areas. Finally at the highest temperature and lowest oxygen partial pressure, active oxidation of SiC occurred for both the fibers and coupons resulting in irregular material attack. Implications for use of SiC/BN/SiC materials for hypersonic vehicle thermal protection systems are summarized.
The statistical mechanics of membranes

Abstract The fluctuations of two-dimensional extended objects (membranes) is a rich and exciting field with many solid results and a wide range of open issues. We review the distinct universality classes of membranes, determined by the local order, and the associated phase diagrams. After a discussion of several physical examples of membranes we turn to the physics of crystalline (or polymerized) membranes in which the individual monomers are rigidly bound. We discuss the phase diagram with particular attention to the dependence on the degree of self-avoidance and anisotropy. In each case we review and discuss analytic, numerical and experimental predictions of critical exponents and other key observables. Particular emphasis is given to the results obtained from the renormalization group e-expansion. The resulting renormalization group flows and fixed points are illustrated graphically. The full technical details necessary to perform actual calculations are presented in the Appendices. We then turn to a discussion of the role of topological defects whose liberation leads to the hexatic and fluid universality classes. We finish with conclusions and a discussion of promising open directions for the future.
Template resolution in XML/HTML

Abstract This paper describes a framework for applying templates to applications and documents on the Web. The primary motivation is the need of Web application developers to separate program logic from presentation logic. A template is a prototypical document or part thereof. It consists of content in the target language, HTML, XML, or plain text, plus markup specifying variable parts of the document. The Template Markup Language (TML) is an application of XML which defines a generic and flexible set of template markup elements. TRIX (Template Resolution in XML/HTML) is a framework for processing TML. It excels in being highly extensible — both in the types of values variables can take, variables being URLs, and in the set of template elements recognized.