cssi/SciSciGPT-SciSciNet huggingface dataset:
The dynamics of multiple neck formation and fragmentation in high rate extension of ductile materials

Abstract Dynamic necking bifurcation in rapidly extending cylindrical rods is investigated. It has been found that both short wavelength and long wavelength perturbations are suppressed by inertia and an intermediate wavelength is favored. The analysis predicts an increase in the number of necks and an increase in the bifurcation strain with increasing extension rate, in agreement with experimental observations. In terms of the number of necks formed as a function of extension rate, good agreement has been found between the experiments and the analysis. At any given aspect ratio, the model also predicts that beyond a critical extension rate, the mode number of the dominant perturbation increases rapidly and the perturbation begins to look more like a surface instability. This could lead to a fragmentation mechanism at high extension speeds which is different from multiple necking. Currently no experimental results are available to test this prediction. Numerical simulations have been conducted to simulate the fragmentation results, using Gurson’s constitutive law along with a porous failure criterion. Good agreement between the experimental observations and the numerical results has been obtained for the fragmentation statistics. However, the numerical results consistently overestimate the number of necks and the fracture strain, possibly due to uncertainty in the constitutive data used, especially at large strains.
A facile preparation of some novel class II mesoionic xanthine acyclonucleosides

The synthesis of the first examples of Class II mesoionic xanthine acyclonucleosides is described. A series of mesoionic anhydro-(8-methoxyalkyl-5-hydroxy-7-oxothiazolo[3,2-a]pyrimidinium hydroxides), Class II mesoionic analogs isoconjugate with xanthine, were prepared by the thermal condensation of methoxyalkyl-2-aminothiazoles with substituted bis(2,4,6-trichlorophenyl)malonic esters. The memoxyalkyl-2-aminothiazoles were prepared via an aromatic nucleophilic substitution reaction between 2-bromothiazole and the appropriate methoxyalkylamine in excess. The resulting 8-methoxyalkyl-substituted mesoionic xanthines were demethylated using iodotrimethylsilane in acetonitrile at room temperature to afford the corresponding mesoionic anhydro-(8-hydroxyalkyl-5-hydroxy-7-oxothiazolo[3,2-a]pyrimidinium hydroxides) as the Class II mesoionic xanthine acyclonucleosides.
Numerical determination of the magnetic field line Hamiltonian

Abstract The structure of a magnetic field is determined by a one-degree-of-freedom; time-dependent Hamiltonian. This Hamiltonian is evaluated for a given field in a perturbed action-angle form. The location and the size of magnetic islands in the given field are determined from Hamiltonian perturbation theory and from an ordinary Poincare plot of the field line trajectories.
TRACKING RIGID BODY MOTION USING THRUSTERS AND MOMENTUM WHEELS

Tracking control laws are developed for a rigid spacecraft using both thrusters and momentum wheels. The model studied comprises a rigid body with external thrusters and with rigid axisymmetric wheels controlled by axial torques. Modified Rodrigues parameters (MRPs) are used to describe the kinematics. The thruster torques and the axial motor torques are computed to track given attitude motions, using the angular velocity error and MRP error to develop linear and nonlinear control laws. Three different controllers are developed. The first controller uses thruster torques based on a bang-bang control law, while momentum wheels are used to correct tracking errors. The second controller is similar, but is designed to use the thruster torques in such a way that the momentum wheels are not used at all unless there are initial condition errors. The third controller uses linear feedback for the wheels and nonlinear feedback for the thrusters. In all three cases, the controllers are shown rigorously to result in globally asymptotically stable closed-loop systems.
CHARGE LOCALIZATION IN DISORDERED COLOSSAL-MAGNETORESISTANCE MANGANITES

The metallic or insulating nature of the paramagnetic phase of the colossal-magnetoresistance manganites is investigated via a double-exchange Hamiltonian with diagonal disorder. The mobility edge trajectory is determined with the transfer-matrix method. Density-of-states calculations indicate that random hopping alone is not sufficient to induce Anderson localization at the Fermi level with 20--30 % doping. We argue that the metal-insulator transition is likely due to the formation of localized polarons from nonuniform extended states as the effective bandwidth is reduced by random hoppings and electron-electron interactions.
The effects of confinement and inertia on the production of droplets

Recent experiments of Sibillo et al., Phys. Rev. Lett. 97:054502, (2006) investigate the effect of walls on flow-induced drop deformation for Stokes flow. The drop and the fluid in which it is suspended have the same viscosities. The capillary numbers vary from 0.4 to 0.46. They find that complex start-up transients are observed with overshoots and undershoots in drop deformation. Drop breakup is inhibited by lowering the gap. The ratio of initial drop radius to wall separation is fixed at 0.34. We show that inertia can enhance elongation to break the drop by examining Reynolds numbers in the range of 1 to 10. The volumes of the daughter drops can be larger than in the unbounded case, and even result in the production of monodisperse droplets.
On the complexity of deciding fair termination of probabilistic concurrent finite-state programs

Abstract In this paper, we consider the fair termination problem for probabilistic concurrent finite-state programs. We analyse the complexity of deciding, given a system of probabilistic concurrent finite-state programs, whether the system will terminate (with probability 1) under five different fairness assumptions. It turns out that these problems are either complete for Ptime , or the second or third level of the alternating logspace hierarchy, even when the number of programs is fixed. However, when a more succinct representation of the inputs is allowed, the problems become either Exptime - or Pspace -complete. Let NLk (AL2k, AL3k, respectively) denote the class of languages that can be accepted by a k log n space bounded NTM (2-alternation bounded ATM, 3-alternation bounded ATM, respectively) with a binary tape alphabet. It has been conjectured that there are problems in NLk that require Ω(nk) deterministic time. Now these problems are in Ptime for every fixed value of k; but if we accept the conjecture, then the order of the polynomial, in each case, grows linearly with the value of k. For succinctly represented instances of k concurrent n-state programs, we show that the problems require Ω(n (k−6) 96 ) deterministic time or are hard for AL2k−2 or AL3k−3. Furthermore, the reductions are such that if we accept the conjecture, then each of the problems require Ω(n (k−2) 8 ) deterministic time. In addition, corresponding upper bounds of O(nd k) deterministic time and d k log n 2- (3-)alternation bounded ATM space (for some positive constant d) are shown; and lower bounds with respect to space are discussed.
Leveraging emerging network services to scale multimedia applications

Multicast services have been used to transmit multimedia data to large receiver groups. Only recently have counterpart network services been introduced to provide similar scalability and anonymity in the opposite direction (i.e. messages from a group of senders destined for a common receiver). In this paper, we explore how these many-to-one services, specifically the concast service, can be used to improve the scalability and performance of multimedia applications. In particular, we show how such services can be used in both the control and data planes to overcome well-known scalability problems (e.g. with Real Time Protocol) that are difficult to solve effectively with end-system approaches alone. We validate our solutions by presenting experimental results taken from prototype video and audio applications we designed and implemented. Our initial results show substantial reductions in congestion-induced loss using these generic services. Copyright © 2003 John Wiley & Sons, Ltd.
Real-Time Traffic Measurement from Single Loop Inductive Signatures

Accurate traffic data acquisition is essential for effective traffic surveillance, which is the backbone of advanced transportation management and information systems (ATMIS). Inductive loop detectors (ILDs) are still widely used for traffic data collection in the United States and many other countries. Three fundamental traffic parameters—speed, volume, and occupancy—are obtainable via single or double (speed-trap) ILDs. Real-time knowledge of such traffic parameters typically is required for use in ATMIS from a single loop detector station, which is the most commonly used. However, vehicle speeds cannot be obtained directly. Hence, the ability to estimate vehicle speeds accurately from single loop detectors is of considerable interest. In addition, operating agencies report that conventional loop detectors are unable to achieve volume count accuracies of more than 90% to 95%. The improved derivation of fundamental real-time traffic parameters, such as speed, volume, occupancy, and vehicle class, from si...
A generating function for Blattner’s formula

Let G be a connected, semisimple Lie group with finite center and let K be a maximal compact subgroup. We investigate a method to compute multiplicities of K-types in the discrete series using a rational expression for a generating function obtained from Blattner's formula. This expression involves a product with a character of an irreducible finite-dimensional representation of K and is valid for any discrete series system. Other results include a new proof of a symmetry of Blattner's formula, and a positivity result for certain low rank examples. We consider in detail the situation for G of type split G 2 . The motivation for this work came from an attempt to understand pictures coming from Blattner's formula, some of which we include in the paper.
Multi-patch model for transport properties of cuprate superconductors

A number of normal state transport properties of cuprate superconductors are analyzed in detail using the Boltzmann equation. The momentum dependence of the electronic structure and the strong momentum anisotropy of the electronic scattering are included in a phenomenological way via a multi-patch model. The Brillouin zone and the Fermi surface are divided in regions where scattering between the electrons is strong and the Fermi velocity is low (hot patches) and in regions where the scattering is weak and the Fermi velocity is large (cold patches). We present several motivations for this phenomenology starting from various microscopic approaches. A solution of the Boltzmann equation in the case of N patches is obtained and an expression for the distribution function away from equilibrium is given. Within this framework, and limiting our analysis to the two patches case, the temperature dependence of resistivity, thermoelectric power, Hall angle, magnetoresistance and thermal Hall conductivity are studied in a systematic way analyzing the role of the patch geometry and the temperature dependence of the scattering rates. In the case of Bi-based cuprates, using ARPES data for the electronic structure, and assuming an inter-patch scattering between hot and cold states with a linear temperature dependence, a reasonable agreement with the available experiments is obtained.
Embedding mesh of trees in the hypercube

Embedding one architecture in another is useful in providing architectural abstractions between different topologies. Through such embeddings the algorithms originally developed for one architecture can be directly mapped to another architecture. This paper describes methods for embedding one-, two-, and three-dimensional mesh of trees in the hypercube. Similar methods may be used for embedding higher-dimensional mesh of trees. This embedding has significant practical importance in enhancing the capabilities of the hypercube since mesh of trees enable extremely fast parallel computation.
Facile Catalyst Separation Without Water: Fluorous Biphase Hydroformylation of Olefins

A novel concept for performing stoichiometric and catalytic chemical transformations has been developed that is based on the limited miscibility of partially or fully fluorinated compounds with nonfluorinated compounds. A fluorous biphase system (FBS) consists of a fluorous phase containing a dissolved reagent or catalyst and another phase, which could be any common organic or nonorganic solvent with limited or no solubility in the fluorous phase. The fluorous phase is defined as the fluorocarbon (mostly perfluorinated alkanes, ethers, and tertiary amines)-rich phase of a biphase system. An FBS compatible reagent or catalyst contains enough fluorous moieties that it will be soluble only or preferentially in the fluorous phase. The most effective fluorous moieties are linear or branched perfluoroalkyl chains with high carbon number; they may also contain heteroatoms. The chemical transformation may occur either in the fluorous phase or at the interface of the two phases. The application of FBS has been demonstrated for the extraction of rhodium from toluene and for the hydroformylation of olefins. The ability to separate a catalyst or a reagent from the products completely at mild conditions could lead to industrial application of homogeneous catalysts or reagents and to the development of more environmentally benign processes.
Design Optimization of Sinusoidal Glass Honeycomb for Flat Plate Solar Collectors

The design of honeycomb made of sinusoidally corrugated glass strips was optimized for use in water-cooled, single-glazed flat plate solar collectors with non-selective black absorbers. Cell diameter (d), cell height (L), and pitch/diameter ratio (P/d) maximizing solar collector performance and cost effectiveness for given cell wall thickness (t sub w) and optical properties of glass were determined from radiative and convective honeycomb characteristics and collector performance all calculated with experimentally validated algorithms. Relative lifetime values were estimated from present materials costs and postulated production methods for corrugated glass honeycomb cover assemblies. A honeycomb with P/d = 1.05, d = 17.4 mm, L = 146 mm and t sub w = 0.15 mm would provide near-optimal performance over the range delta T sub C greater than or equal to 0 C and less than or equal to 80 C and be superior in performance and cost effectiveness to a non-honeycomb collector with a 0.92/0.12 selective black absorber.
Palladium-catalyzed carbonylative cyclization via trapping of acylpalladium derivatives with internal enolates. Its scope and factors affecting the C-to-O ratio

Abstract The Pd-catalyzed carbonylative cyclization reaction involving ω-acyl-substituted acylpalladium derivatives can proceed via intramolecular trapping with either C- or O-enolates; the preferential formation of either 5- or 6-membered rings dictates the C-to-O ratio in the trapping with enolates.
Cell: A Distributed Computing Modularization Concept

This paper presents a new language construct for distributed computing. This construct, called cell, allows one to simulate a variety of language constructs, Its salient features provide the programmer with: 1) an effective communication and synchronization scheme, 2) a mechanism to control the order in which various activities within a cell should be executed. We demonstrate the usefulness of our concepts by providing solutions to a variety of programming exercises.
Tree automata and attribute grammars

The translational mechanism of attribute grammars using tree automata are investigated. The pushdown tree-to-string transducer with a certain synchronization facility as a model to realize transformations by attribute grammars is proposed and its basic properties using tree-walking finite state automata are studied. To demonstrate the utility of this model, it is shown that noncircular attribute grammars are equally powerful as arbitrary attribute grammars, and a method is provided to show that a certain type of transformations is impossible by attribute grammars.
Dissociation of B. Anthracis

Occasional reports of atypical anthrax colonies have been made. These include such observations as those of Preisz,1, 2 Markoff,3 Wagner,4 Gratia,5 etc. Varying significance has been attached to such atypical forms. Preisz noted these peculiar colonies in vaccine cultures and believed them to be contaminations. After reproducing these colony forms from pure line cultures weakened by growth in broth at 42.5° C., he concluded that they were variants arising from the “weakened” culture. Other workers have generally referred to these modifications merely as variations. Markoff stressed the external environment as influencing variation. Wagner suggested a possible analogy between his “teratologische forms” and the “sogenannten Q-Formen in der Typhus-Coli Gruppe.”In the spring of 1926 we obtained, by plating from broth, a dissociation of an apparently “normal” laboratory stock culture of B. anthracis (maintained continuously in the laboratory since 1888) into two colonial types: one was the usual flat, dull ant...
Geodesic scattering of solitonic strings

Abstract We compute the metric on moduli space for the Dabholkar-Harvey string soliton in D =4 to lowest nontrivial order in the string tension. The metric is found to be flat, which implies trivial scattering of the solitons. This result is consistent with an earlier test string calculation of the leading order dynamical force and a computation of the Veneziano amplitude for the scattering of macroscopic strings.
Ab Initio and Density Functional Theory Study of the Geometric Structure, Vibrational Frequency, Torsional Potential, and Isomerization of Dichlorodisulfane (ClSSCl)

The equilibrium geometric structure and vibrational frequency of ClSSCl have been determined at HF, MP2, LSDA, BLYP, B3LYP, BP86, B3P86, and B3PW91 level using different basis sets with diffuse and d and f polarization functions. Comparison with available experimental and theoretical results have been made. The effect of basis set on the accuracy of the prediction of dipole moment has been examined. The effect of internal rotation on the structural parameters has been analyzed, and torsional potentials at ab initio and density functional levels have been determined. Analysis of the relative stability of ClSSCl with respect to SSCl2 using hybrid density functionals at 6-311+G(3df) basis set indicates that the former is more stable by 10−12 kcal mol-1. The activation energy for the isomerization of ClSSCl to SSCl2 has been determined, using the correlated methods, to be between 40 and 48 kcal mol-1.
On the balanced truncation of LTV systems

This note furthers results on the balanced truncation of stable linear time-varying discrete-time systems. The main result contributes better error bounds than the currently available ones in certain model reduction scenarios; this is demonstrated in an example of a four-mass translational system. Also, this note gives new finite error bounds for the balanced truncation of stable eventually periodic models.
High-aspect-ratio rotary polygon micromotor scanners

Abstract This paper describes a polygon micromotor scanner fabricated from single crystal silicon by deep reactive ion etching (DRIE) for in-plane scanning applications. The scanner consists of an outer-rotor wobble micromotor with a 1.4-mm diameter, 200-μm thick rotor. The outer-rotor design circumvents optical beam interference by wires or probes that provide electrical excitation to the motor. A variety of rotor polygon types were designed and fabricated, including those with three, four, six, and eight facets. After fabrication of the components, the scanners were assembled and operated for extended periods in room air using a typical drive signal of 60 V and achieving rotational speeds up to 58 rpm. The 1310-nm optical beam was reflected off the Al-coated sidewall of the polygon rotor using external optics, achieving optical coupling efficiencies of −5.8 dB and a scan angle of 50–110° depending on the number of facets employed. During dynamic optical measurements, 1.8-mm diameter gradient-index (GRIN) lenses were used as optical elements, and a repeatable signal was detected indicating less than 0.5° misalignment of the reflective surface due to rotor wobble or tilt.
Controls on the origin and cycling of riverine dissolved inorganic carbon in the Brazos River, Texas

Rivers draining watersheds that include carbonate bedrock or organic matter (OM)-rich sedimentary rocks frequently have 14C-depleted dissolved inorganic carbon (DIC) relative to rivers draining carbonate- and OM-free watersheds, due to dissolution of carbonate and/or decomposition of ancient OM. However, our results from a subtropical river, the Brazos River in Texas, USA, show that in this watershed human activities appear to dominate basin lithology in controlling the origin and metabolism of DIC. The middle Brazos flows through limestone and coal-bearing bedrock, but DIC isotope data suggest no limestone dissolution or respiration of ancient OM, and instead reflect efficient air–water CO2 exchange, degradation of relatively young OM and photosynthesis in the river as a result of river damming and urban treated wastewater input. The lower Brazos drains only small areas of carbonate and coal-bearing bedrock, but DIC isotope data suggest the strong influence of carbonate dissolution, with a potentially minor contribution from decomposition of old soil organic matter (SOM). Oyster shells and crushed carbonate minerals used in road construction are likely sources of carbonate in the lower Brazos, in addition to natural marl and pedogenic carbonate. Additionally, the generally low pCO2 and high DIC concentration in the Brazos River lead to a low CO2 outgassing:DIC export ratio, distinguishing the Brazos River from other rivers.
Eliminating Islands in High-Pressure Free-Boundary Stellarator Magnetohydrodynamic Equilibrium Solutions

Magnetic islands in free-boundary stellarator equilibria are suppressed using a procedure that iterates the plasma equilibrium equations and, at each iteration, adjusts the coil geometry to cancel resonant fields produced by the plasma. The coils are constrained to satisfy certain measures of engineering acceptability and the plasma is constrained to ensure kink stability. As the iterations continue, the coil geometry and the plasma simultaneously converge to an equilibrium in which the island content is negligible. The method is applied with success to a candidate plasma and coil design for the National Compact Stellarator Experiment [Phys. Plasmas 8, 2083 (2001)].
Treatment of correlation effects in electron momentum density: density functional theory and beyond

Abstract Recent high resolution Compton scattering experiments clearly reveal that there are fundamental limitations to the conventional local density approximation (LDA) based description of the ground state electron momentum density (EMD) in solids. In order to go beyond the framework of the density function theory (DFT), we consider for the correlated system a BCS-like approach in which we start with a singlet pair wavefunction or a ‘geminal’ from which the many body wavefunction is then constructed by taking an antisymmetrized geminal product (AGP). A relatively simple practical implementation of the AGP method is developed where the one-particle orbitals are approximated by the Kohn–Sham solutions used in standard band computations, and the orbital-dependent BCS energy scale Δ i is determined through a readily computed exchange-type integral. The methodology is illustrated by considering EMD and Compton profiles in Li, Be and Al. It is found that in Li the present scheme predicts a substantial renormalization of the LDA result for the EMD; in Be, the computed correlation effect is anisotropic , while in Al, the deviations from the LDA are relatively small. These theoretical predictions are in qualitative accord with the corresponding experimental observations on Li, Be and Al, and indicate the potential of the AGP method for describing correlation effects on the EMD in wide classes of materials.
The repetition property for sequences on tori generated by polynomials or skew-shifts

The repetition property of a sequence in a metric space, a notion introduced by us in an earlier paper, is of importance in the spectral analysis of ergodic Schrodinger operators. It may be used to exclude eigenvalues for such operators. In this paper we study the question of when a sequence on a torus that is generated by a polynomial or a skew-shift has the repetition property. This provides classes of ergodic Schrodinger operators with potentials generated by skew-shifts on tori that have, contrary to earlier belief, no eigenvalues.
Renal Neoplasms in Patients With Renal Cystic Diseases

With advances in diagnostic imaging, small renal masses are being detected earlier and with increased frequency. The differential diagnosis of a small renal mass is extensive and includes a cyst, infarction, focal infection, angiomyolipoma, lymphoma, metastatic neoplasm, oncocytoma, renal cell carcinoma, and pseudotumor [1]. Differentiation is based on the clinical history and specific imaging findings. There are three renal cystic diseases that are strongly associated with solid renal masses. Knowledge of these diseases and the renal neoplasms with which they are associated aids the proper diagnosis and treatment of these patients. In this article, we review acquired cystic kidney disease (ACKD), von Hippel-Lindau disease (VHL), and tuberous sclerosis (TS) and suggest the appropriate diagnostic evaluation when a solid renal mass is discovered.
The syntheses of 1R- and 1S-5-methylenylcamphor and their epoxidation by cytochrome P-450-CAM

Abstract The syntheses of 1R- and 1S-5-methylenylcamphor, camphor analogues in which the two methylene hydrogens at C-5 have been replaced with an exocyclic methylene group, are described. The stereospecific epoxidations of both olefins by Pseudomonas putida cytochrome P450-CAM to give the exo -epoxides are reported. The turnover rates for the epoxidation of the 1R and 1S olefins are ten- and three-fold slower, respectively, than the rates of hydroxylation of 1R- and 1S-camphor.
The Significance of Vertebrate Metamorphosis

It is generally recognized that the anatomical metamorphosis of the vertebrates seems to recapitulate their evolutionary history. However, little attention has been paid to the biochemical changes which precede or accompany the anatomical changes. In the present paper, the author uses the biochemistry of vision as the point of departure for considering the parallel changes in biochemistry, anatomy, and ecology which are involved in vertebrate metamorphosis.
Ultra-short period cepheids in the LMC

Six Cepheids in the Large Magellanic Cloud have been discovered with periods less than one day. They lie at the faint, blue end of the instability strip as would be expected but form a separate Period-Luminosity relation from that for normal Cepheids. Membership in the LMC is based upon the existence of the P-L relationship. Several of the variables have uncertain periods although all apparently have periods under one day. One additional variable has tentatively been identified as a bright Anomalous Cepheid.
Accounting for organizational misconduct

Organizational misconduct (white collar, corporate and occupational crime, unethical behavior, rule violations, etc.) is an increasingly important social concern. This paper proposes that a necessary step toward preventing and treating such misconduct is the understanding of the explanations, called accounts, given by the actor. We argue that the theorizing and findings in the literature on accounts can be organized into a 2×2 matrix framework. The first dimension centers on whether or not the actor admits that some net harm is done by the act, and the second consists of whether or not the actor admits responsibility. When both are admitted (cell 1), the account is a concession, while denial of both constitutes a refusal (cell 4). Admitting responsibility but not harm equates to a justification (cell 2), and the opposite condition is an excuse (cell 3). Building on this matrix, we specify a typology of explanations within each cell which will highlight inter-cell differences. Finally, we explore the implications of this analysis for managers, regulators, and the public.
Molecular Dynamics in Shape Space and Femtosecond Vibrational Spectroscopy of Metal Clusters

We introduce a method of molecular dynamics in shape space aimed at metal clusters. The ionic degrees of freedom are described via a dynamically deformable jellium with inertia parameters derived from an incompressible, irrotational flow. The shell correction method is used to calculate the electronic potential energy surface underlying the dynamics. Our finite-temperature simulations of Ag14 and its ions, following the negative-to-neutral-to-positive scheme, demonstrate the potential of pump-and-probe ultrashort laser pulses as a spectroscopy of cluster shape vibrations.
Efficacy, East and West: François Jullien's Explorations in Strategy

The current explosion of interest in strategic thinking and its applications to business and daily life represents one moment in the millennial quest for a formula for successful decision making an...
The photoionization cross-section of Si

An experiment for the determination of the absorption spectrum of S i was performed using a flash-pyrolysis technique. The material (pure Sulphur) was introduced by vacuum deposition into the absorption cell which was surrounded by a helical flash-lamp. A condensor bank of 120 μF charged to 10 kV was discharged through the flash-lamp. The absorption of the strong flux of light results in the evaporation of the material and in its dissociation. With delays of 100–500 μ sec a Garton source was fired providing the background continuum.
Integrating research into campus and community early childhood programs

Common problems encountered when research is conducted in campus child care facilities are cited and discussed. In addition, specific guidelines are offered to ensure the successful integration of research into a center's overall program. The modification of campus research policies to meet the unique needs of community centers is also discussed.
THE MINIMAL ENTROPY CONJECTURE FOR NONUNIFORM RANK ONE LATTICES

The Besson–Courtois–Gallot theorem is proven for noncompact finite volume Riemannian manifolds. In particular, no bounded geometry assumptions are made. This proves the minimal entropy conjecture for nonuniform rank one lattices.
Dynamics and noise emission of vortex cavitation bubbles

The growth and collapse of a cavitation bubble forming within the core of a line vortex was examined experimentally to determine how the dynamics and noise emission of the elongated cavitation bubble is influenced by the underlying non-cavitating vortex properties. A steady line vortex was formed downstream of a hydrofoil mounted in the test section of a recirculating water channel. A focused pulse of laser light was used to initiate a nucleus in the core of a vortex, allowing for the detailed examination of the growth, splitting and collapse of individual cavitation bubbles as they experience a reduction and recovery of the local static pressure. Images of single-bubble dynamics were captured with two pulse-synchronized high-speed video cameras. The shape and dynamics of single vortex cavitation bubbles are compared to the original vortex properties and the local static pressure in the vortex core, and an analysis was performed to understand the relationship between the non-cavitating vortex properties and the diameter of the elongated cavitation bubble. Acoustic emissions from the bubbles were detected during growing, splitting and collapse, revealing that the acoustic impulse created during collapse was four orders of magnitude higher than the noise emission due to growth and splitting. The dynamics and noise generation of the elongated bubbles are compared to that of spherical cavitation bubbles in quiescent flow. These data indicate that the core size and circulation are insufficient to scale the developed vortex cavitation. The non-cavitating vortex circulation and core size are not sufficient to scale the bubble dynamics, even though the single-phase pressure field is uniquely scaled by these parameters. A simple analytical model of the equilibrium state of the elongated cavitation bubble suggests that there are multiple possible equilibrium values of the elongated bubble radius, each with varying tangential velocities at the bubble interface. Thus, the details of the bubble dynamics and bubble-flow interactions will set the final bubble dimensions.
Dynamic tariffs with asymmetric information

Recent developments in dynamic game theory are applied to determine when two countries can sustain freer trade given that they determine trade policies non-cooperatively. Countries know their own level of protection, but not the other country's level of protection. Using import trigger strategies, cooperation (in the form of low tariffs) can be supported, although there are periodic reversionary (high tariff) episodes. However, if terms of trade trigger strategies are used, cooperation does not occur.
Inexact matching of ontology graphs using expectation-maximization

We present a new method for mapping ontology schemas that address similar domains. The problem of ontology matching is crucial since we are witnessing a decentralized development and publication of ontological data. We formulate the problem of inferring a match between two ontologies as a maximum likelihood problem, and solve it using the technique of expectation-maximization (EM). Specifically, we adopt directed graphs as our model for ontology schemas and use a generalized version of EM to arrive at a map between the nodes of the graphs. We exploit the structural, lexical and instance similarity between the graphs, and differ from the previous approaches in the way we utilize them to arrive at, a possibly inexact, match. Inexact matching is the process of finding a best possible match between the two graphs when exact matching is not possible or is computationally difficult. In order to scale the method to large ontologies, we identify the computational bottlenecks and adapt the generalized EM by using a memory bounded partitioning scheme. We provide comparative experimental results in support of our method on two well-known ontology alignment benchmarks and discuss their implications.
General physics motivations for numerical simulations of quantum field theory

Abstract In this introductory article a brief description of quantum field theories (QFT) is presented with emphasis on the distinction between strongly and weakly coupled theories. A case is made for using numerical simulations to solve QCD, the regnant theory describing the interactions between quarks and gluons. I present an overview of what these calculations involve, why they are hard, and why they are tailor made for parallel computers. Finally, I try to communicate the excitement amongst the practitioners by giving examples of the quantities we will be able to calculate to within a few percent accuracy in the next five years.
DYNAMIC CAPABILITIES, WHAT ARE THEY?

This paper focuses on dynamic capabilities and, more generally, the resource-based view of the firm. We argue that dynamic capabilities are a set of specific and identifiable processes such as product development, strategic decision making, and alliancing. They are neither vague nor tautological. Although dynamic capabilities are idiosyncratic in their details and path dependent in their emergence, they have significant commonalities across firms (popularly termed ‘best practice’). This suggests that they are more homogeneous, fungible, equifinal, and substitutable than is usually assumed. In moderately dynamic markets, dynamic capabilities resemble the traditional conception of routines. They are detailed, analytic, stable processes with predictable outcomes. In contrast, in high-velocity markets, they are simple, highly experiential and fragile processes with unpredictable outcomes. Finally, well-known learning mechanisms guide the evolution of dynamic capabilities. In moderately dynamic markets, the evolutionary emphasis is on variation. In high-velocity markets, it is on selection. At the level of RBV, we conclude that traditional RBV misidentifies the locus of long-term competitive advantage in dynamic markets, overemphasizes the strategic logic of leverage, and reaches a boundary condition in high-velocity markets. Copyright © 2000 John Wiley & Sons, Ltd.
Semantic issues in the design of languages for debugging

The Seeheim Model of human-computer interaction partitions an interactive application into a user-interface, a dialogue controller and the application itself. One of the formal techniques of implementing the dialogue controller is based on context-free grammars and automata. In this work, we modify an off-the-shelf compiler generator (YACC) to generate the dialogue controller. The dialogue controller is then integrated into the popular X-window system, to create an interactive-application generator. The actions of the user drive the automaton, which in turn controls the application.
Yb14MnSb11: New High Efficiency Thermoelectric Material for Power Generation

Thermoelectric materials provide a key solution to energy problems through the conversion of heat into electrical energy. We report that the complex Zintl compound, Yb14MnSb11, breaks a 2-decade stagnation in high-temperature (>900 K), p-type materials development for thermoelectric power generation. This material achieves quadrupled efficiency and virtually doubled figure of merit over the current state-of-the-art, SiGe, thus earmarking it superior for thermoelectric applications in segmented devices. Yb14MnSb11 represents the first complex Zintl phase with substantially higher figure of merit and efficiency than any other competing materials, opening a new class of thermoelectric compounds with remarkable chemical and physical properties.
Electron-phonon scattering rates in quantum wires

Abstract Electron-phonon scattering rates for quantum wires of arbitrary shapes are calculated rigorously within the dielectric continuum approach for the phonons. An integral equation approach is developed for the interface phonons, and the contribution to the scattering rates from the confined phonon modes are expressed in terms of the interface modes by a simple relation. Detailed results are given for the intrasubband and intersubband transition rates as functions of the electron energy and of the wire width for wires of rectangular cross section. The relative importance of the interface and confined phonons is discussed as a function of wire size. A quantitative appraisal is given of scattering rates obtained using simple separable approximations for the phonons.
Central-Station Solar Hydrogen Power Plant

Solar power towers can be used to make hydrogen on a large scale. Electrolyzers could be used to convert solar electricity produced by the power tower to hydrogen, but this process is relatively inefficient. Rather, efficiency can be much improved if solar heat is directly converted to hydrogen via a thermochemical process. In the research summarized here, the marriage of a high-temperature (∼1000°C) power tower with a sulfuric acid/ hybrid thermochemical cycle was studied. The concept combines a solar power tower, a solid-particle receiver, a particle thermal energy storage system, and a hybrid-sulfuric-acid cycle. The cycle is "hybrid" because it produces hydrogen with a combination of thermal input and an electrolyzer. This solar thermochemical plant is predicted to produce hydrogen at a much lower cost than a solar-electrolyzer plant of similar size. To date, only small lab-scale tests have been conducted to demonstrate the feasibility of a few of the subsystems and a key immediate issue is demonstration of flow stability within the solid-particle receiver. The paper describes the systems analysis that led to the favorable economic conclusions and discusses the future development path.
The Interpreter In An Undergraduate Compilers Course

An undergraduate compilers course poses significant challenges to students, in both the conceptual richness of the major components and in the programming effort necessary to implement them. In this paper, I argue that a related architecture, the interpreter, serves as an effective conceptual framework in which to teach some of the later stages of the compiler pipeline. This framework can serve both to unify some of the major concepts that are taught in a typical undergraduate course and to structure the implementation of a semester-long compiler project.
Lower entropy bounds and particle number fluctuations in a Fermi sea

In this letter we demonstrate, in an elementary manner, that given a partition of the single particle Hilbert space into orthogonal subspaces, a Fermi sea may be factored into pairs of entangled modes, similar to a BCS state. We derive expressions for the entropy and for the particle number fluctuations of a subspace of a Fermi sea, at zero and finite temperatures, and relate these by a lower bound on the entropy. As an application we investigate analytically and numerically these quantities for electrons in the lowest Landau level of a quantum Hall sample.
Performance evaluation of a massively parallel I/O subsystem

Presented are the trace-driven simulation results of a study conducted to evaluate the performance of the internal parallel I/O subsystem of the Vulcan MPP architecture. The system sizes evaluated vary from 16 to 512 nodes. The results show that a compute node to I/O node ratio of four is the most cost effective for all system sizes, showing high scalability. Also, processor-to-processor communication effects are negligible for small message sizes and the greater the fraction of I/O reads, the better the I/O performance. Worse case I/O node placement is within 13% of more efficient placement strategies. Introducing parallelism into the internal I/O subsystem improves I/O performance significantly.
Synthesis of α-methyl ketones by a selective, iridium-catalyzed cyclopropanol ring-opening reaction

Abstract A mild method for synthesizing α-methyl ketones from substituted cyclopropanols is reported. This process, catalyzed by [Cp∗IrCl2]2, cleaves cyclopropanol rings regioselectively and more efficiently than the other conditions examined. While tertiary cyclopropanols afford α-methyl ketones, secondary cyclopropanols and cyclopropyl silyl ethers are less reactive and yield other isomerization products.
An interatomic potential for saturated hydrocarbons based on the modified embedded-atom method

In this work, we developed an interatomic potential for saturated hydrocarbons using the modified embedded-atom method (MEAM), a reactive semi-empirical many-body potential based on density functional theory and pair potentials. We parameterized the potential by fitting to a large experimental and first-principles (FP) database consisting of (1) bond distances, bond angles, and atomization energies at 0 K of a homologous series of alkanes and their select isomers from methane to n-octane, (2) the potential energy curves of H2, CH, and C2 diatomics, (3) the potential energy curves of hydrogen, methane, ethane, and propane dimers, i.e., (H2)2, (CH4)2, (C2H6)2, and (C3H8)2, respectively, and (4) pressure–volume–temperature (PVT) data of a dense high-pressure methane system with the density of 0.5534 g cc−1. We compared the atomization energies and geometries of a range of linear alkanes, cycloalkanes, and free radicals calculated from the MEAM potential to those calculated by other commonly used reactive potentials for hydrocarbons, i.e., second-generation reactive empirical bond order (REBO) and reactive force field (ReaxFF). MEAM reproduced the experimental and/or FP data with accuracy comparable to or better than REBO or ReaxFF. The experimental PVT data for a relatively large series of methane, ethane, propane, and butane systems with different densities were predicted reasonably well by the MEAM potential. Although the MEAM formalism has been applied to atomic systems with predominantly metallic bonding in the past, the current work demonstrates the promising extension of the MEAM potential to covalently bonded molecular systems, specifically saturated hydrocarbons and saturated hydrocarbon-based polymers. The MEAM potential has already been parameterized for a large number of metallic unary, binary, ternary, carbide, nitride, and hydride systems, and extending it to saturated hydrocarbons provides a reliable and transferable potential for atomistic/molecular studies of complex material phenomena involving hydrocarbon–metal or polymer–metal interfaces, polymer–metal nanocomposites, fracture and failure in hydrocarbon-based polymers, etc. The latter is especially true since MEAM is a reactive potential that allows for dynamic bond formation and bond breaking during simulation. Our results show that MEAM predicts the energetics of two major chemical reactions for saturated hydrocarbons, i.e., breaking a C–C and a C–H bond, reasonably well. However, the current parameterization does not accurately reproduce the energetics and structures of unsaturated hydrocarbons and, therefore, should not be applied to such systems.
Capital Gains, Dividend Yields, and Expected Inflation

One explanation for the negative relationship between short-horizon stock returns and inflation is that inflation proxies (inversely) for expected future real output. In this paper, I examine the possibility that inflation also proxies for variation in real price/dividend ratios (excess returns). I show that when the covariance between real price/dividend ratios and inflation is nonzero, the relationship between returns and expected inflation differs for the two components of returns: dividend yields and capital gains returns. My empirical evidence demonstrates that dividend yields and capital gains are related differently to expected inflation in U.S. and foreign markets. PRIOR STUDIES FIND that short-horizon stock returns are negatively related to both anticipated and unanticipated inflation in post-1953 data.1 These studies focus on the relationship between total returns and inflation for aggregate stock market and industry portfolios. I extend the literature by examining the relationships between expected inflation and the two components of stock returns: dividend yields and capital gains returns. I interpret my results in the context of Fama's (1981) "proxy hypothesis" Fama (1981) proposes that inflation proxies for real activity. He posits that rational market responses to an increase (decrease) in expected future output are increases (decreases) in both stock prices and in the demand for real money. If the change in money demand is not accommodated by a like change in money supply, the quantity theory of money implies an opposite movement in the price level. The negative relationship between stock returns and inflation is observed because stock prices and the price level react oppositely to changes in expected future output.