cssi/SciSciGPT-SciSciNet huggingface dataset:
Goodput maximization in cooperative networks with ARQ

In this paper, the average successful throughput, i.e., goodput, of a coded 3-node cooperative network is studied in a Rayleigh fading environment. It is assumed that a simple automatic repeat request (ARQ) technique is employed in the network so that erroneously received packets are retransmitted until successful delivery. The relay is assumed to operate in either amplify-and-forward (AF) or decode-and-forward (DF) mode. Under these assumptions, retransmission mechanisms and protocols are described, and the average time required to send information successfully is determined. Subsequently, the goodput for both AF and DF relaying is formulated. The tradeoffs and interactions between the goodput, transmission rates, and relay location are investigated and optimal strategies are identified.
The Common Law Character of English Charters: Spontaneous Order in the Constitutions of Clarendon (1164)

The Constitutions of Clarendon are presented as an illustration of the common-law character of English charters. Although formally renounced and abrogated shortly after ratification, the Constitutions remain a fundamental basis for the separation of church and state. Analysis of the historical literature reveals that spontaneous order subsumes many kinds of positive law and designed order. The emergence of spontaneous order in common law is described, defined, and contrasted with positive legislation. Spontaneous order allowed secular society to grow and flourish. It is acknowledged that charters played a secondary role in making positive law, and were precursors to modern positive legislation. The implications of positive versus spontaneously evolved law for economic efficiency are discussed. The historical context and aftermath of the Constitutions is presented, and their content is discussed and analyzed from an economic perspective. The key legal problem the Constitutions addressed was the relationship between competing secular and canon-law jurisdictions, which suffered from inherent conflicts-of-interest. This provided economic decision makers perverse incentives. Prior to the Constitutions, the Church was able to act as plaintiff and judge in civil disputes and intimidate litigants by exercising criminal jurisdiction. Finally, the Constitutions are discussed and presented as an example of spontaneously evolved law, which promoted greater entrepreneurial freedom and economic efficiency.
Mind the gap: law, institutional analysis and socioeconomics

'In a capitalist society, to say markets or business is to say the law.' (Sklar, 1988, p. 86) Providing an extended case study of the co-evolution of change in US labor and employment law and change in the US economy, this article argues that unless socioeconomists focus on law as a sustained object of inquiry in its own right, they will fail to adequately understand or explain state-economy interaction in capitalist democracies. The article proposes a rule-resource institutional framework to better conceptualize law as an institution and to elucidate the multifaceted political and cultural processes through which legal action and institutions reciprocally shape and are shaped by economic action and institutions in intersecting legal and economic institutional fields. Because legal rules/schema and legality are socially constructed and mobilized as resources through interpretive and political processes involving cognitive and normative-evaluative as well as instrumental components, law likewise affects the economy through a multi-dimensional set of social mechanisms, rather than by reshaping cost-benefit calculations only. Similarly, law helps constitute not just economic interests, strategies and power, but also everyday economic meanings, identities, roles, relationships and structures, and norms, values, ideas and ideals, including the concept of economic rationality itself. Law may sometimes function as an exogenous shock with respect to the economy, but mutual endogeneity between legal and economic meanings, enactments and power in overlapping and interpenetrating legal and economic institutional fields will likely be the norm rather than the exception.
A Matroid Generalization of a Result on Row-Latin Rectangles

Let A be an m×n matrix in which the entries of each row are all distinct. A. A. Drisko (1998, J. Combin. Theory Ser. A84, 181?195) showed that if m?2n?1, then A has a transversal: a set of n distinct entries with no two in the same row or column. We generalize this to matrices with entries in the ground set of a matroid. For such a matrix A, we show that if each row of A forms an independent set, then we can require the transversal to be independent as well. We determine the complexity of an algorithm based on the proof of this result. Finally, we observe that m?2n?1 appears to force the existence of not merely one but many transversals. We discuss a number of conjectures related to this observation (some of which involve matroids and some of which do not).
LDA and GGA calculations for high-pressure phase transitions in ZnO and MgO

We report total energy and electronic structure calculations for ZnO in the B4 (wurtzite), B3 (zinc blende), B1 (rocksalt), and B2 (CsCl) crystal structures over a range of unit cell volumes. We employed both the local-density approximation (LDA) and the PBE96 form of the generalized gradient approximation (GGA) together with optimized Gaussian basis sets to expand the crystal orbitals and periodic electron density. In agreement with earlier ab initio calculations and with experiment, we find that the B4 phase of ZnO is slightly lower in energy than the B3 phase, and that it transforms first to the B1 structure under applied pressure. The equilibrium transition pressure ${p}_{T1}$ is 6.6 GPa at the LDA level of theory and 9.3 GPa in the GGA, compared to experimental values around 9 GPa. This confirms a trend seen by other workers in which the LDA underestimates structural transition pressures which are more accurately predicted by the GGA. At much higher compression, we predict that the B1 phase of ZnO will transform to the B2 (cesium chloride) structure at ${p}_{T2}=260\mathrm{GPa}$ (LDA) or 256 GPa (GGA) indicating that gradient corrections are small for this material at megabar pressures. This is the first quantitative prediction of this transition in ZnO, and should be testable with diamond-anvil techniques. We predict that ZnO remains a semiconductor up to ${p}_{T2}.$ For comparison we find that the B1 to B2 transition in MgO occurs at 515 GPa with either LDA or GGA, in excellent agreement with other ab initio predictions.
A 12.5 GHz-spaced optical frequency comb spanning >400 nm for near-infrared astronomical spectrograph calibration

A 12.5 GHz-spaced optical frequency comb locked to a global positioning system disciplined oscillator for near-infrared (IR) spectrograph calibration is presented. The comb is generated via filtering a 250 MHz-spaced comb. Subsequent nonlinear broadening of the 12.5 GHz comb extends the wavelength range to cover 1380–1820 nm, providing complete coverage over the H-band transmission window of earth’s atmosphere. Finite suppression of spurious sidemodes, optical linewidth, and instability of the comb has been examined to estimate potential wavelength biases in spectrograph calibration. Sidemode suppression varies between 20 and 45 dB, and the optical linewidth is ∼350 kHz at 1550 nm. The comb frequency uncertainty is bounded by ±30 kHz (corresponding to a radial velocity of ±5 cm/s), limited by the global positioning system disciplined oscillator reference. These results indicate that this comb can readily support radial velocity measurements below 1 m/s in the near IR.
CONSTRUCTING SEIFERT SURFACES FROM n-BRIDGE LINK PROJECTIONS

This paper presents a new algorithm for constructing Seifert surfaces from n-bridge projections of links. The algorithm, &#x1d504;, produces minimal complexity surfaces for large classes of braids and alternating links. In addition, we consider a family of knots for which canonical genus is strictly greater than genus, (gc(K) > g(K)), and show that &#x1d504; builds surfaces realizing the knot genus g(K). We also present a generalization of Seifert's algorithm which constructs surfaces representing arbitrary relative second homology classes in a link complement.
Anomalous Dissipation in a Stochastically Forced Infinite-Dimensional System of Coupled Oscillators

We study a system of stochastically forced infinite-dimensional coupled harmonic oscillators. Although this system formally conserves energy and is not explicitly dissipative, we show that it has a nontrivial invariant probability measure. This phenomenon, which has no finite dimensional equivalent, is due to the appearance of some anomalous dissipation mechanism which transports energy to infinity. This prevents the energy from building up locally and allows the system to converge to the invariant measure. The invariant measure is constructed explicitly and some of its properties are analyzed.
Order reduction of large scale DAE models

A technique for the adaptive order reduction of large scale non-linear differential algebraic equations (DAEs) is outlined in this report. The order reduction is adaptive, requiring no preprocessing simulations or special model configuration. The required tuning parameters are the error tolerances for the DAE variables. The order reduction is accomplished in three steps. First, adaptive proper orthogonal decomposition (POD) is used to reduce the number of differential states. POD is made adaptive by dynamically adjusting the order of the reduced model based on the magnitude of the ordinary differential equation (ODE) residuals. As a second step, the algebraic states are partitioned into successive implicit sets of variables and equations by reconstructing the sparsity pattern into a lower triangular block form. Finally, in situ adaptive tabulation (ISAT) is used to adaptively transform the implicit sets into linear explicit approximations. Special consideration of large scale models permits non-linear model reduction theory to be extended to an open equation format.
Control of Polymer Topology by Chain‐Walking Catalysts

Chain-walking catalysts are demonstrated to control the branching topology of polyethylene by tuning the competition between monomer insertion and chain isomerization (walking). The topology of the polyethylene was controlled from linear with moderate branching to hyperbranched to dendritic. Although overall branching number and distribution of short chain branching are relatively constant, the topology of the polyethylene changes from linear polyethylene with moderate branches at high ethylene pressures to a dendritic polyethylene at low pressures. This provides a straightforward one-pot process for making polymers with a full range of tunable topologies.
Contact structures on 3–manifolds are deformations of foliations

In this note we observe, answering a question of Eliashberg and Thurston in \cite{EliashbergThurston98}, that all contact structures on a closed oriented 3--manifold are $C^\infty$-deformations of foliations.
Digital computer solution of differential equations in real time

Digital computers have been used for some time now to obtain the solutions of differential equations. The first electronic digital computer, the Electronic Numerical Integrator and Computer, (ENIAC) was designed and built at The Moore School of Electrical Engineering under contract with the Aberdeen Proving Ground for the specific purpose of integrating the differential equations of motion of a projectile. This computer was very successful at this task. Digital computers have been used to prepare tables of mathematical functions which are solutions of differential equations and one occasionally reads that a digital computer has been used to check, but not in real time, the results of an analog simulation of some system described by differential equations. When the subject of the digital computer solution of differential equations in real time is considered, questions that have to be answered arise in connection with speed, accuracy, cost, ease of maintenance, and flexibility. In this paper, it will be attempted to discuss these points within the framework of a specific application, the Operational Flight Trainer.
Synchronicity from synchronized chaos

The synchronization of loosely-coupled chaotic oscillators, a phenomenon investigated intensively for the last two decades, may realize the philosophical concept of “synchronicity”—the commonplace notion that related eventsmysteriously occur at the same time. When extended to continuous media and/or large discrete arrays, and when general (non-identical) correspondences are considered between states, intermittent synchronous relationships indeed become ubiquitous. Meaningful synchronicity follows naturally if meaningful events are identified with coherent structures, defined by internal synchronization between remote degrees of freedom; a condition that has been posited as necessary for synchronizability with an external system. The important case of synchronization between mind and matter is realized if mind is analogized to a computer model, synchronizing with a sporadically observed system, as in meteorological data assimilation. Evidence for the ubiquity of synchronization is reviewed along with recent proposals that: (1) synchronization of different models of the same objective process may be an expeditious route to improved computational modeling and may also describe the functioning of conscious brains; and (2) the nonlocality in quantum phenomena implied by Bell’s theorem may be explained in a variety of deterministic (hidden variable) interpretations if the quantum world resides on a generalized synchronization “manifold”.
EXISTENCE OF GOOD SWEEPOUTS ON CLOSED MANIFOLDS

In this note we establish estimates for the harmonic map heat flow from into a closed manifold, and we use it to construct sweepouts with the following good property: each curve in the tightened sweepout, whose energy is close to the maximal energy of curves in the sweepout, is itself close to a closed geodesic.
Analysis of Cracked Laminates with Holes Using the Boundary Force Method

The boundary force method is an indirect boundary element technique for the analysis of composite laminates with holes and cracks which uses the orthotropic elasticity solution for a concentrated horizontal and vertical force applied at a given point in a cracked infinite sheet. The orthotropic formulation of the method is verified by comparison with accepted solutions for a counter-crack specimen that is subjected to uniaxial tension. Parametric studies are conducted for two configurations for which no orthotropic solutions are available: cracks emanating from a circular hole, and a four-hole cracked specimen; both are loaded in uniaxial tension.
High-throughput screening system for catalytic hydrogen-producing materials.

A high-throughput screening system and methodology were developed for libraries of hydrogen (H2) producing catalytic materials. The system is based on the chemo-optical properties of WO3, which give rise to reflectance changes in the presence of H2. Pd-coated WO3 sensors were synthesized and examined for their hydrogen sensitivity, wavelength-dependent reflectance, and performance in the presence of water vapor. For high-throughput screening, a polypropylene reactor block was designed and constructed to house 8 × 12 catalyst libraries deposited as thin films. When the library and reactor block are assembled together, 96 independent microreactor units are formed. A large-area Pd/WO3 sensor film covers and seals all microreactors, forming a 96-element 2-D H2 sensor array. As H2 is produced differentially across the library, the reflectance changes of the Pd/WO3 film are monitored by reflectivity sensors that scan the surface every 30 s. The time-dependent changes in reflectance indicate relative rates of H2...
The effect of aging on entrepreneurial behavior

Abstract Empirical evidence shows that younger individuals are more likely to start a new firm than older ones. As a result, the age distribution of a population may be important for the rate of new firm creation. Building upon Becker's theory of time allocation, we present a model in which individuals select a career path according to the dynamic interplay of age, wealth and risk aversion. Our analysis complements existing literature on the motivations of entrepreneurial behavior and discusses the potential implications of age for individuals' employment status choices.
Dynamical thermal behavior and thermal self-stability of microcavities

Stability and continuous operation are important for almost any use of a microcavity, we demonstrate here experimentally and theoretically self-stable equilibrium solution for a pump-microcavity system; this mechanism is derived by the thermal nonlinearity.
Hypolipidemic Activity of 3-Amino-1-(2,3,4-mononitro-, mono-, or dihalophenyl)propan-1-ones in Rodents

A series of 3-amino-1-(2,3,4-mononitro-, mono-, or dihalo-phenyl)propan-1-ones were synthesized and shown to be effective in lowering both serum cholesterol and triglyceride levels significantly in CF1 mice and Sprague-Dawley rats. All analogs showed better activity than the standard drugs, lovastatin and clofibrate, in reducing the serum cholesterol and triglyceride levels in mice at 8 mg/kg/day intraperitoneally. The best active analogs, 3-morpholino-1(3-nitrophenyl)propan-1-one (4) and 3-piperidino-1-(3-nitrophenyl)propan-1-one (5), exhibited 58% and 67% reduction of serum cholesterol levels, respectively, and 42% and 46% reduction of serum triglyceride levels, respectively, after 16 days of administration at 8 mg/kg/day intraperitoneally in CF1 mice. In Sprague-Dawley rats at 8 mg/kg/day oral administration, both compounds (4 and 5) significantly decreased the serum cholesterol and triglyceride levels. Rat tissue lipid levels were reduced significantly by compound 4, while less effects resulted from compound 5. The cholesterol and triglyceride levels in chylomicrons, VLDL, and LDL fractions were reduced by both analogs while the HDL cholesterol levels were significantly increased. Compound 5 was also effective in lowering serum cholesterol and triglyceride levels in hyperlipidemic mice, at 8 mg/kg/day intraperitoneally, but not effective in hyperlipidemic rats at 8 mg/kg/day orally. Cholesterol and triglyceride lowering effects of the agents were correlated with inhibition of the activities of liver acetyl CoA synthetase, HMG CoA reductase, phosphatidylate phosphohydrolase, and lipoprotein lipase, and with elevation of the activity of cholesterol ester hydrolase.
Application of sucrose phosphorylase reaction in one-pot enzymatic galactosylation: Scavenger of phosphate and generation of glucose 1-phosphate in situ

Abstract Sucrose phosphorylase (EC 2.4.1.7) reaction was combined into one-pot galactosyltransferase reaction in which the enzyme scavenged for the accumulated inorganic phosphate and utilized it with sucrose to generate in situ glucose I-phosphate. that was the essential component for galactosylation.
Land values and housing rents in urban Japan

Abstract This paper describes and systematically explains observed variation in land values and housing rents in urban Japan. It fits a structural model's reduced form equations to intertemporal data over 35 years, intercity data across 27 major cities, and intracity data in the three largest metropolitan areas. Explanatory variables are population, income, their growth rates, the interest rate, the inflation rate, urban land supply, and distance from the city center.
Scales and cosmological applications of M theory

Abstract The dependence of the gauge coupling constants of Hořava-Witten models on the size of the compact dimensions are discussed. Values of all factors are computed for the first time. Non-standard embedding are considered for the first time and illustrate the possibility of a hidden sector with smaller tree level gauge coupling than the observable one. Possible presence and effects of dark matter on the hidden wall are emphasized.
Intradimer and interdimer exchange coupling in the mixed ligand complex bis-μ-chloro-bis[chloro(4-methylthiazole)dimethylformamidecopper(II)]: a spin ladder system

Abstract The structure of the mixed ligand complex bis-μ-chloro-bis[chloro(4-methylthiazole)dimethylformamidecopper(II)] has been determined from three-dimensional X-ray counter data. The complex [Cu-(C4H5NS)(DMF)Cl2]2 crystallizes in the monoclinic space group P 2 1 n with two formula units in a cell of dimensions a = 7.349(7), b = 20.306(7), c = 8.909(3) A and β = 112.53(6)°. The final weighted R factor is 0.032 based on 1646 data. In this first example of a mixed ligand bis-μ-chloro-copper(II) complex, copper is five-coordinate, with the coordination geometry being distorted from an idealized tetragonal pyramidal. The Cu2Cl2 bridging unit is constrained to be planar by the presence of a center of symmetry, and the CuCl distances are 2.296(2) and 2.724(1) A with a CuCl⋯Cu′ angle of 95.29(7)°. Magnetic susceptibility measurements reveal antiferromagnetic exchange coupling, and the best fit of equation for an exchange coupled pair of S = 1 2 ions yields J = −1.7 cm−1 and g = 2.105. The exchange coupling constant lies in the range of values for a φ R o value of 35 deg A−1. The quality of the fit is markedly improved if intermider exchange interactions are taken into account. The dimers pack in the solid state to form a ladder-like structure with copper(II)sulfur contacts of 3.906(3) A. Best fit exchange coupling constants for the spin ladder of −1.17 and −1.0 cm−1 were obtained from a calculation on a closed ring of 10 spins with nearest neighbor and next-nearest neighbor interactions.
The Effect of Cryosurgical Ablation of the Prostate on Erectile Function

Objective To investigate the incidence and identify the possible cause of erectile dysfunction after cryoablation of the prostate. Patients and methods Erectile function was examined prospectively in 15 sexually active men (aged 59–72 years) who underwent cryoablation of the prostate for clinically localized prostate cancer. Erectile function was assessed before and 6 months after treatment; after intracavernosal injection with 10 μg of prostaglandin E1 (PGE1), the degree and duration of erection, the size of the cavernosal arteries, the penile arterial blood flow velocity, and the time to achieve peak flow were evaluated using high-resolution ultrasonography and colour pulsed-Doppler spectral analysis. Results Post-operatively, all patients initially reported an inability to achieve an erection sufficient for vaginal intercourse. At 6 months′ follow-up, erectile dysfunction persisted in nine, with minimal or no response to the intracavernosal PGE1 injections, there was a significant decrease in the peak velocity of blood flow within cavernosal arteries and a significant increase in the time to achieve peak arterial flow. Conclusion Although many factors may contribute to erectile dysfunction after cryoablation of the prostate, vascular injury plays a major role.
X-ray absorption edge determination of the oxidation state and coordination number of copper: application to the type 3 site in Rhus vernicifera laccase and its reaction with oxygen

Cu X-ray absorption edge features of 19 Cu(I) and 40 Cu(II) model complexes have been systematically studied and correlated with oxidation state and geometry. Studies of Cu(I) model complexes with different coordination number reveal that an 8983-8984-eV peak (assigned as the Cu 1s ..-->.. 4p transition) can be correlated in energy, shape, and intensity with ligation and site geometry of the cuprous ion. These Cu(I) edge features have been qualitatively interpreted with ligand field concepts. Alternatively, no Cu(II) complex exhibits a peak below 8985.0 eV. The limited intensity observed in the 8983-8985-eV region for some Cu(II) complexes is associated with the tail of an absorption peak at approx. 8986 eV which is affected by the covalency of the equatorial ligands. These models studies allow accurate calibration of a normalized difference edge procedure which is used for the quantitative determination of Cu(I) content in copper complexes of mixed oxidation state composition. This normalized difference edge analysis is then used to quantitatively determine the oxidation states of the copper sites in type 2 copper-depleted (T2D) and native forms of the multicopper oxidase, Rhus vernicifera laccase. The type 3 site of the T2D laccase is found to be fully reduced and stable tomore » oxidation by O/sub 2/ or by 25-fold protein equivalents of ferricyanide, but it can be oxidized by reaction with peroxide. The increase in intensity of the 330-nm absorption feature which results from peroxide titration of T2D laccase is found to correlate linearly with the percent of oxidation of the binuclear copper site.« less
Low-Mass Stars and Brown Dwarfs in NGC 2024: Constraints on the Substellar Mass Function

We present results from a near-infrared spectroscopic study of candidate brown dwarfs and low-mass stars in the young cluster NGC 2024. Using FLAMINGOS on the KPNO 2.1 m and 4 m telescopes, we have obtained spectra of ~70 new members of the cluster and classified them via the prominent J- and H-band water absorption features. Derived spectral types range from ~M1 to later than M8 with typical classification errors of 0.5-1 subclasses. By combining these spectral types with JHK photometry, we place these objects on the H-R diagram and use pre-main-sequence evolutionary models to infer masses and ages. The mean age for this low-mass population of NGC 2024 is 0.5 Myr, and derived masses range from ~0.7 to 0.02 M☉ with 23 objects falling below the hydrogen-burning limit. The logarithmic mass function rises to a peak at ~0.2 M☉ before turning over and declining into the substellar regime. There is a possible secondary peak at ~0.035 M☉; however, the errors are also consistent with a flat IMF in this region. The ratio of brown dwarfs to stars is similar to that found in the Trapezium but roughly twice the ratio found in IC 348, leading us to conclude that the substellar IMF in young clusters may be dependent on the local star-forming environment.
A myosin from a higher plant has structural similarities to class V myosins

In plant cells, myosin is believed to be the molecular motor responsible for actin-based motility processes such as cytoplasmic streaming and directed vesicle transport. In an effort to characterize plant myosin, a cDNA encoding a myosin heavy chain was isolated from Arabidopsis thaliana. The predicted product of the MYA1 gene is 173 kDa and is structurally similar to the class V myosins. It is composed of the highly-conserved NH2-terminal "head" domain, a putative calmodulin-binding "neck" domain an alpha-helical coiled-coil domain, and a COOH-terminal domain. Northern blot analysis shows that the Arabidopsis MYA1 gene is expressed in all the major plant tissues (flower, leaf, root, and stem). We suggest that the MYA1 myosin may be involved in a general intracellular transport process in plant cells.
An efficient synthetic approach to 6,5'-(S)- and 6,5'-(R)-cyclouridine.

Here we present new routes for the efficient syntheses of 6,5′-(S)- and 6,5′-(R)-cyclouridine. The syntheses utilize readily accessible uridine as a starting material. This route to the R diastereomer is significantly more efficient than previous synthetic efforts, allowing us to obtain large amounts of pure material for future biological testing.
SPECTRAL ENERGY DISTRIBUTIONS OF YOUNG STARS IN IC 348: THE ROLE OF DISKS IN ANGULAR MOMENTUM EVOLUTION OF YOUNG, LOW-MASS STARS

Theoretical work suggests that a young star's angular momentum content and rotation rate may be strongly influenced by magnetic interactions with its circumstellar disk. A generic prediction of these 'disk-locking' theories is that a disk-locked star will be forced to co-rotate with the Keplerian angular velocity of the inner edge of the disk; that is, the disk's inner-truncation radius should equal its co-rotation radius. These theories have also been interpreted to suggest a gross correlation between young stars' rotation periods and the structural properties of their circumstellar disks, such that slowly rotating stars possess close-in disks that enforce the star's slow rotation, whereas rapidly rotating stars possess anemic or evacuated inner disks that are unable to brake the stars and instead the stars spin up as they contract. To test these expectations, we model the spectral energy distributions (SEDs) of 33 young stars in IC 348 with known rotation periods and infrared excesses indicating the presence of circumstellar disks. For each star, we match the observed SED, typically sampling 0.6-8.0 {mu}m, to a grid of 200,000 pre-computed star+disk radiative transfer models, from which we infer the disk's inner-truncation radius. We then compare this truncation radius to the disk's co-rotation radius,more » calculated from the star's measured rotation period. We do not find obvious differences in the disk truncation radii of slow rotators versus rapid rotators. This holds true both at the level of whether close-in disk material is present at all, and in analyzing the precise location of the inner disk edge relative to the co-rotation radius among the subset of stars with close-in disk material. One interpretation is that disk locking is unimportant for the IC 348 stars in our sample. Alternatively, if disk locking does operate, then it must operate on both the slow and rapid rotators, potentially producing both spin-up and spin-down torques, and the transition from the disk-locked state to the disk-released state must occur more rapidly than the stellar contraction timescale.« less
Numerical analysis of a time-headway bus route model

Abstract In this paper, we consider a time-headway model, introduced in Ref. [Physica A 296 (2001) 320], for buses on a bus route. By including a simple no-passing rule, we are able to enumerate and study the unstable modes of a homogeneous system. We then discuss the application of the model to realistic scenarios, showing that the range of reasonable parameter values is more restricted than one might imagine. We end by showing that strict stability in a homogeneous bus route requires careful monitoring by each bus of the bus in front of it, but in many cases this is unnecessary because the time it takes for the instability to appear is longer than a bus would normally spend on a route.
CDC definitions of nosocomial surgical site infections, 1992: a modification of CDC definitions of surgical wound infections.

In 1988, the Centers for Disease Control (CDC) published definitions of nosocomial infections However, because of journalistic style and space constraints, these definitions lacked some of the detail provided to National Nosocomial Infections Surveillance (NNIS) System hospitals in the NNIS Manual (unpublished). After the NNIS System hospitals had had considerable experience with the definitions and in response to a request for review by The Surgical Wound Infection Task Force, a group composed of members of The Society for Hospital Epidemiology of America, the Association for Practitioners in Infection Control, the Surgical Infection Society, and the CDC, we slightly modified the definition of surgical wound infection and changed the name to surgical site infection (SSI).
Two-way wireless video communication using Randomized cooperation, Network Coding and packet level FEC

Two-way real-time video communication in wireless networks requires high bandwidth, low delay and error resiliency. This paper addresses these demands by proposing a system with the integration of Network Coding (NC), user cooperation using Randomized Distributed Space-time Coding (R-DSTC) and packet level Forward Error Correction (FEC) under a one-way delay constraint. Simulation results show that the proposed scheme significantly outperforms both conventional direct transmission as well as R-DSTC based two-way cooperative transmission, and is most effective when the distance between the users is large.
Robust platoon-stable controller design for autonomous intelligent vehicles

A new variable structure longitudinal controller is designed and analyzed for an autonomous intelligent vehicle. The proposed controller not only guarantees individual vehicle stability, but also platoon stability. Moreover, the achieved platoon stability is proven to be robust with respect to vehicle parameter uncertainties and unknown time varying disturbances. Explicit transient bounds are obtained which indicate ways of choosing controller parameters for comfortable driving.
General Ginsparg–Wilson fermions and index

Abstract We show rigorously that for general Ginsparg–Wilson fermions the dimensions of the geometric eigenspace and of the algebraic one for zero modes agree so that the index theorem on the lattice is not spoiled by unwanted additional terms.
Review of Unquenched Results

Abstract One of the major frontiers of lattice field theory is the inclusion of light fermions in simulations, particularly in pursuit of accurate, first principles predictions from lattice QCD. With dedicated Teraflops-scale computers currently simulating QCD, another step towards precision full QCD simulations is underway. In addition to ongoing staggered and Wilson fermion simulations, first results from full QCD with domain wall fermions are availabeleAfter some discussion of work toward better algorithms, simulations completed to date will be discussed.
Astrophysics of Super-massive Black Hole Mergers

We present here an overview of recent work in the subject of astrophysical manifestations of super-massive black hole (SMBH) mergers. This is a field that has been traditionally driven by theoretical work, but in recent years has also generated a great deal of interest and excitement in the observational astronomy community. In particular, the electromagnetic (EM) counterparts to SMBH mergers provide the means to detect and characterize these highly energetic events at cosmological distances, even in the absence of a space-based gravitational-wave observatory. In addition to providing a mechanism for observing SMBH mergers, EM counterparts also give important information about the environments in which these remarkable events take place, thus teaching us about the mechanisms through which galaxies form and evolve symbiotically with their central black holes.
Separate measurement of current density under the channel and the shoulder in PEM fuel cells

In a proton exchange membrane (PEM) fuel cell current density under the shoulder can be very different from that under the gas channel and the knowledge of where the current density is higher is critical in flow field designs in order to optimize fuel cell performance. Yet, up to date this issue has not been resolved. In this study, a novel yet simple approach was adopted to directly measure the current densities under the channel and the shoulder in PEM fuel cells separately. In this approach, the cathode catalyst layer was so designed that either the area under the shoulder or the area under the channel was loaded with catalyst. Such a design guaranteed the currents generated under the shoulder and the channel could be measured separately. Experimental results showed that the current density produced under the channel was lower than that under the shoulder except in the high current density region. To determine the causes of higher current density under the shoulder two additional sets of experiments were conducted. First, a silver mesh was added on the top of the gas diffusion layer (GDL) and the experimental results showed that GDL lateral electrical resistance was not the cause and it had a negligible effect on lateral current density variation. Secondly, the total through-plane electric resistance of the GDL and the catalyst layer under different compressions was measured and the results showed that the difference between the total through-plane electrical resistance under the channel and under the shoulder was large enough to cause the higher current density under the shoulder.
Anomalous diffusion in two-dimensional potentials with hexagonal symmetry

The diffusion process in a Hamiltonian dynamical system describing the motion of a particle in a two-dimensional (2D) potential with hexagonal symmetry is studied. It is shown that, depending on the energy of the particle, various transport processes can exist: normal (Brownian) diffusion, anomalous diffusion, and ballistic transport. The relationship between these transport processes and the underlying structure of the phase space of the Hamiltonian dynamical system is investigated. The anomalous transport is studied in detail in two particular cases: in the first case, inside the chaotic sea there exist self-similar structures with fractal properties while in the second case the transport takes place in the presence of multilayered structures. It is demonstrated that structures of the second type can lead to a physical situation in which the transport becomes ballistic. Also, it is shown that for all cases in which the diffusive transport is anomalous the trajectories of the diffusing particles contain long segments of regular motion, the length of these segments being described by Levy probability density functions. Finally, the numerical values of the parameters which describe the diffusion processes are compared with those predicted by existing theoretical models.
Retro-rendering with vector-valued light: producing local illumination from the transport equation

Many rendering algorithms can be understood as numerical solvers for the light-transport equation. Local illumination is probably the most widely implemented rendering algorithm: it is simple, fast, and encoded in 3D graphics hardware. It is not, however, derived as a solution to the light-transport equation. We show that the light-transport equation can be re-interpreted to produce local illumination by using vector-valued light and matrix-valued reflectance. This result fills an important gap in the theory of rendering. Using this framework, local and global illumination result from merely changing the values of parameters in the governing equation, permitting the equation and its algorithmic implementation to remain fixed.
The Cost of Employee Stock Option Grants: An Empirical Analysis

This study presents empirical evidence on the ex post costs of employee stock option (ESO) grants to issuing firms and examines whether the Black–Scholes [1973] model provides reasonable estimates of these values. Because there are no market prices for ESOs, the traditional avenues for testing option–pricing models are unavailable. This research relies instead on techniques from the economic forecasting literature, viewing model values as forecasts of the options’ payoff. The theoretically appropriate rate at which to discount ESO payoffs is derived under the maintained hypothesis that the Black–Scholes model is valid. This rate is used in estimating ex post ESO costs at the time of grant, which are then compared with Black–Scholes estimates using Theil’s [1966] tests of forecast rationality. Based on a sample of 966 ESO grants over 1963–1984, the results suggest that the Black–Scholes model, adjusted for concavity in the time to exercise using the Hemmer, Matsunaga, and Shevlin [1994] procedure, appears to provide reasonable estimates of ex post ESO costs for the average ESO grant. However, there is significant variability in the amount of model error on an individual grant basis.
Affine Deligne–Lusztig varieties associated to additive affine Weyl group elements

Abstract Affine Deligne–Lusztig varieties can be thought of as affine analogs of classical Deligne–Lusztig varieties, or Frobenius-twisted analogs of Schubert varieties. We provide a method for proving a non-emptiness statement for affine Deligne–Lusztig varieties inside the affine flag variety associated to affine Weyl group elements satisfying a certain length additivity hypothesis. In particular, we prove that non-emptiness holds whenever it is conjectured to do so for alcoves in the shrunken dominant Weyl chamber, providing a partial converse to the emptiness results of Gortz, Haines, Kottwitz, and Reuman. Our technique involves the work of Geck and Pfeiffer on cuspidal conjugacy classes, in addition to an analysis of the combinatorics of certain fully commutative elements in the finite Weyl group.
Quantum mechanics with explicit time dependence

Abstract We investigate quantum mechanical Hamiltonians with explicit time dependence. We find a class of models in which an analogue of the time-independent Schrodinger equation exists. Among the models in this class is a new exactly soluble model, the harmonic oscillator with frequency inversely proportional to time.
π4s + π2s cycloadditions: Allyl anions plus ethylene

Abstract Ab initio calculations failed to locate the expected transition structure with Cs symmetry for the concerted π4s + π2s cycloaddition of allyl anion with ethylene. Unsymmetrical structures were found that satisfied the normal criteria for first order saddle points, i.e. one imaginary frequency. Similarly, cycloadditions between ethylene with 2-fluoroallyl anion, 2-azaallyl anion CH2NCH2(−), and the lithium-complexed 2-azaallyl system CH2NCH2Li failed to generate first order transition structures with Cs symmetry. Calculations at the MP2(FC)/6-311++G(d) level show that allyl anion prefers a structure with C2 symmetry as opposed to the classical (planar) C2v structure.
ALOHA packet broadcasting: a retrospect

Packet broadcasting is a technique whereby data is sent from one node in a net to another by attaching address information to the data to form a packet---typically from 30 to 1000 bits in length. The packet is then broadcast over a communication channel which is shared by a large number of nodes in the net; as the packet is received by these nodes the address is scanned and the packet is accepted by the proper addressee (or addressees) and ignored by the others. The physical communication channel employed by a packet broadcasting net can be a ground based radio channel, a satellite transponder or a cable.
Fast fourier transform analysis of computer-acquired friction data

A commercial computer program for data acquisition and analysis has been used to facilitate the evaluation of the frequency content of friction force data obtained from a sliding wear test. The program uses a fast Fourier transform (FFT) algorithm to calculate the frequency spectrum of the friction force. The validity of the FFT program has been demonstrated by applying it to a recently published example that used a detailed mathematical treatment to remove an oscillatory component from friction data. When applied to friction force data from a pin-on-disk sliding wear test of NBD 200 silicon nitride sliding on NBD 100 silicon nitride, filtering of the dominant frequencies revealed by the FFT method reduces both the general dispersion of the friction values and almost completely eliminates localized signal perturbations. Successive filtering steps permit the association of particular frequencies with observed signal disturbances. Although the mean friction value in this example is not greatly altered by th...
Velocity Autocorrelations for Hard Spheres

A study of the velocity autocorrelation function for hard spheres over the entire fluid density region shows that deviations from exponential behavior are small. At very low density a small positive deviation is found which is accounted for in the Boltzmann theory of the self-diffusion coefficient. At higher densities the principal non-Markovian process is identified with a surprisingly long persistence of velocity currents. At still higher densities, near solidification, anticorrelating backscattering events predominate.
[Fe/H] relations for c-type RR Lyrae variables based upon Fourier coefficients

[Fe /H]-Φ31-P relations are found for c-type RR Lyrae stars in globular clusters. The relations are analogous to that found by Jurcsik & Kovacs for field ab-type RR Lyrae stars, where a longer period correlates with lower metallicity values for similar values of the Fourier coefficient Φ 31 . The relations obtained here are used to determine the metallicity of field c-type RR Lyrae stars, those within co Cen, the Large Magellanic Cloud and toward the galactic bulge. The results are found to compare favourably to metallicity values obtained elsewhere.
Synthesis of crossed [2 + 2] photocycloadducts: a novel approach to the synthesis of bridged bicyclic alkenes.

A solution to the synthesis of “crossed” intramolecular [2 + 2] photocycloadducts has been achieved. Through the use of a temporary heteroatom linker, the equivalent of a crossed photocycloadduct can be accessed at the expensive of the normal “straight” adduct. Selectivity as high as 94:6 for the “crossed” adduct has been observed.
Leading-twist single-transverse-spin asymmetries: Drell–Yan and deep-inelastic scattering

Abstract Recently, Brodsky, Hwang and Schmidt have proposed a new mechanism that gives a transverse spin symmetry at leading twist in semi-inclusive deep-inelastic scattering. I show that the new mechanism is compatible with factorization and is due to a transverse-spin asymmetry in the kT distribution of quarks in a hadron (the “Sivers asymmetry”). An earlier proof that the Sivers asymmetry vanishes because of time-reversal invariance is invalidated by the path-ordered exponential of the gluon field in the operator definition of parton densities. Instead, the time-reversal argument shows that the Sivers asymmetry is reversed in sign in hadron-induced hard processes (e.g., Drell–Yan), thereby violating naive universality of parton densities. Previous phenomenology with time-reversal-odd parton densities is therefore validated.
Lifting the Iron Curtain: Toward an Understanding of the Iron Stars XX Oph and AS 325

We present new optical, near-infrared, and archival ultraviolet observations of XX Ophiuchi and AS 325, two proposed "iron" stars. These unusual stars have optical spectra dominated by emission lines arising from hydrogen, as well as ionized metals such as iron, chromium, and titanium. Both stars have been classified as "iron" stars, and a number of exotic models have been presented for their origin. Using 2 years of moderately high resolution optical spectroscopy, the first high signal-to-noise ratio K-band spectroscopy of these sources (which reveals stellar photospheric absorption lines), and new near-infrared interferometric observations, we confirm that both systems are composed of two stars, likely binaries, containing a hot Be star with an evolved late-type secondary. The hydrogen emission features arise in the hot wind from the Be star, while the corresponding P-Cygni absorption lines are produced from dense material in the expanding, radiation-driven wind around each system. The optical Fe ii emission lines are pumped by ultraviolet Fe ii absorption lines through fluorescence. Contrary to some claims in the literature, the spectral features of XX Oph and AS 325 are quite similar, evidence that they are comparable systems. We examine the variability of the spectral morphology and radial velocity motions of both sources. We also study the variability of XX Oph during a major photometric event and find that the spectral nature of the system varies during the event. A comparison of the velocity of the absorption- line components in our new spectra with those in the literature show that the structure of the stellar wind from XX Oph has changed since the system was observed in 1951.