cssi/SciSciGPT-SciSciNet huggingface dataset:
Higher derivative brane couplings from T-duality

The Wess-Zumino coupling on D-branes in string theory is known to receive higher derivative corrections which couple the Ramond-Ramond potential to terms involving the square of the spacetime curvature tensor. Consistency with T-duality implies that the branes should also have four-derivative couplings that involve the NS-NS B-field. We use T-duality to predict some of these couplings. We then confirm these results with string worldsheet computations by evaluating disc amplitudes with insertions of one R-R and two NS-NS vertex operators.
Corpus structure, language models, and ad hoc information retrieval

Most previous work on the recently developed language-modeling approach to information retrieval focuses on document-specific characteristics, and therefore does not take into account the structure of the surrounding corpus. We propose a novel algorithmic framework in which information provided by document-based language models is enhanced by the incorporation of information drawn from clusters of similar documents. Using this framework, we develop a suite of new algorithms. Even the simplest typically outperforms the standard language-modeling approach in precision and recall, and our new interpolation algorithm posts statistically significant improvements for both metrics over all three corpora tested.
Viscous/inviscid analysis of curved sub- or supersonic wall jets

T features of a viscous/inviscid curved wall jet model, under development for application to the analysis of circulation-controlled airfoil flowfields, are described. The model solves the surface-oriented parabolized Navier-Stokes equations using pressure-split methodology for subsonic wall jets and shock-capturing methodology for supersonic wall jets. A hybrid two-layer turbulence model is employed that combines a damped VanDriest inner layer formulation with a curvature-corrected, two-equation ke model outer region formulation. Procedures for performing the strongly interactive coupling of the wall jet solution with an external potential flow solver are discussed. Preliminary calculations for simple wall jets are shown to compare quite favorably with both mean flow and turbulent measurements.
The political economy of dissonance

Cognitive dissonance is defined as the psychological discomfort or annoyance that may exist when an individual's choice is not consistent with his values and beliefs. Dissonance may cause an individual to reconsider his values and beliefs, enter new choices with different parameters, respond to the constraints imposed, or change his individual preference function. This paper extends Festinger's (1957) theory of cognitive dissonance to the work of public choice theorists and seeks to explain the incentives of the iron triangle to foment and quell dissonance. Examples are provided for specific environmental and health and safety risks.
Sampling-based sweep planning to exploit local planarity in the inspection of complex 3D structures

We present a hybrid algorithm that plans feasible paths for 100% sensor coverage of complex 3D structures. The structures to be inspected are segmented to isolate planar areas, and back-and-forth sweep paths are generated to view as much of these planar areas as possible while avoiding collision. A randomized planning procedure fills in the remaining gaps in coverage. The problem of selecting an order to traverse the elements of the inspection is solved by reduction to the traveling salesman problem. We present results of the planning algorithm for an autonomous underwater vehicle inspecting the in-water portion of a ship hull. The randomized configurations succeed in observing confined and occluded areas, while the 2D sweep paths succeed in covering the open areas.
A Pattern Measure

In this paper we propose numerical measures for evaluating the aesthetic interest of simple patterns. The patterns consist of elements (symbols, pixels, etc) in regular square arrays. The measures depend on two characteristics of the patterns: the number of different types of element, and the number of symmetries in their arrangement. We define two complementary composite measures L and C for the degree of pattern in a design, and compute them here for 2 × 2 and 6 × 6 arrays. The results distinguish simple from high-variation cases. We suspect that the measure L corresponds to the degree that human beings intuitively feel a design to be “interesting”, so this model would aid in quantifying the visual connection of two-dimensional designs with viewers. The other composite measure C based on these numerical properties characterizes the extent of randomness of an array. Combining symbol variety with symmetry calculations allows us to employ hierarchical scaling to count the relative impact of different level...
MANAGERIAL INCENTIVES AND THE PRICE EFFECTS OF MERGERS

Most analysis of market power assumes that managers are perfect agents for shareholders. This paper relaxes that assumption. When managers of a multi-product firm exert unobservable effort to improve product quality, there is a trade-off between providing adequate effort incentives and ensuring sufficient price-coordination between the product divisions. This makes some intra-firm price competition optimal, explaining why many multi-product firms allow for competition between divisions. When there are effort spillovers, the optimal amount of price competition can be as great as when the products are under separate ownership. Even with some profit-sharing, intra-firm price competition can reduce quality-adjusted price, which has important implications for antitrust policy.
A lower bound for quantifying overlap effects: An empirical approach

Abstract Among the many features that are implemented in today’s microprocessors there are some that have the capability of reducing the execution time via overlapping of different operations. Overlapping of instructions with other instructions, and overlapping of computation with memory activities are the main way in which execution time is reduced. In this paper we will introduce a notion of overlap and its definition, and a few different ways to capture its effects. We will characterize some of the ASCI benchmarks using the overlap and some other quantities related to it. Also, we will present a characterization of the overlap effects using a lower bound derived empirically from measured data. We will conclude by using the lower bound to estimate other components of the overall execution time.
Synthesis of a versatile 2 (1H)-pyrazinone core for the preparation of Tissue Factor-Factor VIIa inhibitors

A new, general synthetic route to 2(1H)-pyrazinones 11 is described. The four-step synthesis is accomplished utilizing a regioselective hydrolysis and N-alkylation. These compounds efficiently undergo metal-catalyzed cross-coupling reactions to install P2 diversity groups in the 6-position, which can be used to refine the SAR of the S2 pocket of the Tissue Factor/Factor VIIa (TF/VIIa) complex.
Simulations of atomic trajectories near a dielectric surface

We present a semiclassical model of an atom moving in the evanescent field of a microtoroidal resonator. Atoms falling through whispering-gallery modes can achieve strong, coherent coupling with the cavity at distances of approximately 100 nm from the surface; in this regime, surface-induced Casmir–Polder level shifts become significant for atomic motion and detection. Atomic transit events detected in recent experiments are analyzed with our simulation, which is extended to consider atom trapping in the evanescent field of a microtoroid.
Implicit Finite-Difference Procedures for the Computation of Vortex Wakes

Implicit finite-difference procedures for the primitive form of the incompressible Navier-Stokes and the compressible Euler equations are used to compute vortex wake flows. The partial differential equations in strong conservation-law form are transformed to cluster grid points in regions with large changes in vorticity. In addition to clustering, fourth-order accurate, spatial difference operators are used to help resolve the flowfield gradients. The use of implicit time-differencing permits large time steps to be taken since temporal variations are typically small. Computational efficiency is achieved by approximate factorization. Both two-dimensional and preliminary three-dimensional calculations are described. I. Introduction T HE concentrated vorticity in the near wake of a large aircraft can pose a destructive threat to smaller aircraft within the same airspace. Consequently, experimental and theoretical efforts have been under way to understand, predict (for use in avoidance systems), and possibly reduce the vortex wake hazard. Most theoretical models developed to treat this problem rely on tracing discrete vortices,1"3 but an alternate and potentially more powerful approach is to use finitedifference procedures.4'5 Computer programs based on such methods can ultimately account for flowfield nonlinear effects with few ad hoc assumptions. Implicit finite-difference procedures are developed here to solve the incompressible Navier-Stokes equations and compressible Euler equations for simplified two- and threedimensional, unsteady vortex wake flows. This paper is divided into five interdependent sections. The flowfield and its numerical implications are discussed in Sec. II. The incompressible equations are developed for simulation as a system of first-order partial-differential equations in Sec. Ill, and the finite-difference algorithms are described in Sec. IV. Simulation based on the compressible flow equations is discussed in Sec. V. and, finally, simple wake-vortex flow calculations using both kinds of modeling are presented in Sec. VI.
Is Lumpy Investment Relevant for the Business Cycle

The lumpiness of investment activity at the plant level is a well‐established fact. Previous research has suggested that such discrete and occasional adjustments have significant aggregate implications. In particular, it has been argued that changes in plants’ willingness to invest in response to aggregate shocks can at times generate large movements in total investment demand. In this study, I reassess these predictions in a general equilibrium environment. Specifically, assuming nonconvex costs of capital adjustment, I derive generalized (S, s) adjustment rules yielding lumpy plant‐level investment within an otherwise standard equilibrium business cycle model. In contrast to previous partial equilibrium analyses, model results reveal that the aggregate effects of lumpy investment are negligible. In general equilibrium, households’ preference for relatively smooth consumption profiles offsets changes in aggregate investment demand implied by the introduction of lumpy plant‐level investment. As a result, ...
Beacon-Assisted Spectrum Access with Cooperative Cognitive Transmitter and Receiver

Spectrum access is an important function of cognitive radios for detecting and utilizing spectrum holes without harming the legacy systems. In this paper, we propose novel cooperative communication models and show how deploying such cooperations between a pair of secondary transmitter and receiver assists them in identifying spectrum opportunities more reliably. These cooperations are facilitated by dynamically and opportunistically assigning one of the secondary users as a relay to assist the other one, which results in more efficient spectrum hole detection. Also, we investigate the impact of erroneous detection of spectrum holes and thereof missing communication opportunities on the capacity of the secondary channel. The capacity of the secondary users with interference-avoiding spectrum access is affected by 1) how effectively the availability of vacant spectrum is sensed by the secondary transmitter-receiver pair, and 2) how correlated are the perceptions of the secondary transmitter-receiver pair about network spectral activity. We show that both factors are improved by using the proposed cooperative protocols. One of the proposed protocols requires explicit information exchange in the network. Such information exchange in practice is prone to wireless channel errors (i.e., is imperfect) and costs bandwidth loss. We analyze the effects of such imperfect information exchange on the capacity as well as the effect of bandwidth cost on the achievable throughput. The protocols are also extended to multiuser secondary networks.
Advance Bandwidth Scheduling Algorithms in Dedicated Networks

An increasing number of high performance research network testbeds and production networks have the capability of provisioning dedicated channels for high speed data transfer in support of large scale scientific applications. Each dedicated channel in these networks typically consists of one or more physical links that are shared by multiple applications in both time and bandwidth through in advance reservation. The design of efficient bandwidth scheduling algorithms is critical to maximizing the utilization of dedicated network resources and meeting diverse end-to-end transport performance requirements. The topology of a dedicated network is represented by a graph, where each link maintains a list of residual bandwidths specified as segmented constant functions of time. Given a graph with an aggregated time-bandwidth table combining the reservation information on all links, designated source, and destination vertices, and a specified data size, we formulate and investigate five bandwidth scheduling problems to minimize the data transfer end time under different path and bandwidth constraints. variable path with variable bandwidth (VPVB), which computes the widest (highest bandwidth) path in each time slot; fixed path with variable bandwidth (FPVB), which computes a fixed path with varying bandwidths across different time slots; variable path with fixed bandwidth (VPFB), which computes one path in each time slot with the same bandwidth; fixed path with fixed bandwidth (FPFB), which computes a fixed path with a constant bandwidth; and multiple fixed paths with fixed bandwidths (MFPFB), which computes multiple concurrent fixed paths with constant bandwidths. Among these problems, VPVB represents the most flexible scenario where the network resources are fully utilized and the minimal transfer end time is achieved, while FPFB imposes the most stringent transport conditions by fixing both path and bandwidth. We design an optimal algorithm for each of these scheduling problems. VPVB is solved using an extension of the classical Dijkstra's algorithm, and FPVB is solved using Maximum Permutation Algorithm, which tries all possible permutations of throughputs at different time slots to obtain the minimal transfer end time. The algorithm for VPFB, FPFB, and MFPFB are based on Adjacent Time Slots Search, which finds the minimum transfer end time by examining the possibility of data transfer in any number of contiguous time slots. All these algorithms are of polynomial or pseudo polynomial time complexity with respect to the network size and the total number of time slots in a bandwidth reservation table.
The four Hs of tribal tourism: Acoma — a pueblo case study

The American Indian pueblo of Acoma is examined in terms of the four criteria of tribal or ethnic tourism development: Habitat, Heritage, History and Handicrafts. The resident population effectively developed and currently manages their visitor industry, and is a model for indigenous leadership and participation.
A general class of additively decomposable inequality measures

This paper presents and characterizes a two-parameter class of inequality measures that contains the generalized entropy measures, the variance of logarithms, the path independent measures of Foster and Shneyerov (1999) and several new classes of measures. The key axiom is a generalized form of additive decomposability which defines the within-group and between-group inequality terms using a generalized mean in place of the arithmetic mean. Our characterization result is proved without invoking any regularity assumption (such as continuity) on the functional form of the inequality measure; instead, it relies on a minimal form of the transfer principle – or consistency with the Lorenz criterion – over two-person distributions.
From solitons to many-body systems

We present a bridge between the KP soliton equations and the Calogero–Moser many-body systems through noncommutative algebraic geometry. The Calogero-Moser systems have a natural geometric interpretation as flows on spaces of spectral curves on a ruled surface. We explain how the meromorphic solutions of the KP hierarchy have an interpretation via a noncommutative ruled surface. Namely, we identify KP Lax operators with vector bundles on quantized cotangent spaces (formulated technically in terms of D-modules). A geometric duality (a variant of the Fourier–Mukai transform) then identifies the parameter space for such vector bundles with that for the spectral curves and sends the KP flows to the Calogero–Moser flows. It follows that the motion and collisions of the poles of the rational, trigonometric and elliptic solutions of the KP hierarchy, as well as of its multicomponent analogs, are governed by the (spin) Calogero–Moser systems on cuspidal, nodal and smooth genus one curves. This provides geometric explanations and generalizations of results of Airault–McKean–Moser, Krichever and Wilson. The present paper is an overview of work to appear in [BN2].
A relaxation approach to patched-grid calculations with the Euler equations

A conservative zonal-boundary condition that was used with explicit integration schemes is extended to implicit, upwind, relaxation schemes; in particular to the Osher scheme. The rate of convergence was found to increase considerably with the use of the implicit, relaxation-zonal scheme when compared to the explicit scheme. The relaxation-zonal scheme has also been used in a time-accurate mode. Results demonstrating the time accuracy of the scheme and the feasibility of performing calculations in cases where some parts of the given system move relative to others (for example, rotor-stator configurations) are presented.
The synthesis of a series of 3,5-disubstituted tetrahydro-1H-imidazole-2,4-diones utilizing lithium aluminum hydride

A series of 3,5-disubstituted tetrahydro-1H-imidazole-2,4-diones were synthesized from the corresponding urea methyl ester precursors utilizing lithium aluminum hydride as the cyclization agent.
Critical behavior and Griffiths effects in the disordered contact process

We study the nonequilibrium phase transition in the one-dimensional contact process with quenched spatial disorder by means of large-scale Monte Carlo simulations for times up to ${10}^{9}$ and system sizes up to ${10}^{7}$ sites. In agreement with recent predictions of an infinite-randomness fixed point, our simulations demonstrate activated (exponential) dynamical scaling at the critical point. The critical behavior turns out to be universal, even for weak disorder. However, the approach to this asymptotic behavior is extremely slow, with crossover times of the order of ${10}^{4}$ or larger. In the Griffiths region between the clean and the dirty critical points, we find power-law dynamical behavior with continuously varying exponents. We discuss the generality of our findings and relate them to a broader theory of rare region effects at phase transitions with quenched disorder.
An Observational Determination of the Bolometric Quasar Luminosity Function

We combine a large set of quasar luminosity function (QLF) measurements from the rest-frame optical, soft and hard X-ray, and near- and mid-IR bands to determine the bolometric QLF in the redshift interval z = 0-6. Accounting for the observed distributions of quasar column densities and variation of SED shapes, as well as their dependence on luminosity, makes it possible to integrate the observations in a reliable manner and provides a baseline in redshift and luminosity larger than that of any individual survey. We infer the QLF break luminosity and faint-end slope out to z ~ 4.5 and confirm at high significance (10 σ) previous claims of a flattening in both the faint- and bright-end slopes with redshift. With the best-fit estimates of the column density distribution and quasar SED, which both depend on luminosity, a single bolometric QLF self-consistently reproduces the observed QLFs in all bands and at all redshifts for which we compile measurements. Ignoring this luminosity dependence does not yield a self-consistent bolometric QLF and there is no evidence for any additional dependence on redshift. We calculate the expected relic black hole mass function and mass density, cosmic X-ray background, and ionization rate as a function of redshift and find that they are consistent with existing measurements. The peak in the total quasar luminosity density is well constrained at z = 2.15 ± 0.05. We provide a number of fitting functions to the bolometric QLF and its manifestations in various bands, as well as a script to return the QLF at arbitrary frequency and redshift from these fits.
The Myth of Neutrality

Humanitarian aid should be non‐political. That was the conclusion adopted at the Spring 1995 meeting in Madrid of the International Committee of the Red Cross (ICRC) and other humanitarian non‐governmental organizations (NGOs). This was endorsed in their new Code of Conduct, which indicates that aid will be given “regardless of the race, creed or nationality of the recipients.” It further states that “We will not tie the promise, delivery or distribution of assistance to the embracing or acceptance of a particular political or religious creed.” This provides a laudable standard to which humanitarian actors should aspire. But it is severely bounded by the circumstances in which aid organizations operate.
On the endogeneity of trading arrangements

Abstract It is common in the literature to assume that trading arrangements are exogenous. Yet, the sheer variety of existing arrangements suggests that they are in fact subject to choice. This paper formally endogenizes the choice of a trading arrangement. I argue that if the design of an arrangement affects trading outcomes, then rational, strategically-acting agents will opt for the arrangement that facilitates trading and leads to price discovery. I demonstrate the general argument in the context of emerging foreign exchange markets which exhibit a particularly wide variety of trading arrangements.
Do Global Trade Distortions Still Harm Developing Country Farmers

The authors estimate the impact of global merchandise trade distortions and services regulations on agricultural value added in various countries. Using the latest versions of the Global Trade Analysis Project (GTAP) database and the GTAP-AGR model of the global economy, their results suggest real net farm incomes would rise in developing countries with a move to free trade, thereby alleviating rural poverty. This occurs despite a terms of trade deterioration for developing countries that are net food importers or that enjoy preferential access to agricultural markets of high-income countries. The authors also show, for several large developing countries, the contribution of their own versus other countries' trade policies.
The LISA integrated model

LISA has unique needs that argue for an aggressive modelling effort. These models ultimately need to forecast and interrelate the behaviour of the science input, structure, optics, control systems and many other factors that affect the performance of the flight hardware. In addition, many components of these integrated models will also be used separately for the evaluation and investigation of design choices, technology development, and integration and test. This paper presents an overview of the LISA integrated modelling effort.
Simulations of Protein Folding

Abstract We have developed a simple, phenomenological, Monte-Carlo code that predicts the three-dimensional structure of globular proteins from the DNA sequences that define them. We have applied this code to two small proteins, the villin headpiece (1VII) and cole1 rop (1ROP). Our code folds both proteins to within 5 A rms of their native structures.
Quadratic-exponential moment error bounds for digital communication systems

Abstract By utilizing the theory of moment spaces, upper and lower bounds are obtained for error probability of digital communication systems, based on the use ofquadratic- exponential moments of the inter-symbol interference random variables. Some bound can be evaluated numerically with minimal computational effort, while other bounds require more effort. Even the computationally simple bounds can be extremely tight.
The Cosmic Crystallinity Conundrum: Clues from IRAS 17495-2534

Since their discovery, cosmic crystalline silicates have presented several challenges to understanding dust formation and evolution. The mid-infrared spectrum of IRAS 17495–2534, a highly obscured oxygen-rich asymptotic giant branch (AGB) star, is the only source observed to date which exhibits a clear crystalline silicate absorption feature. This provides an unprecedented opportunity to test competing hypotheses for dust formation. Observed spectral features suggest that both amorphous and crystalline dust is dominated by forsterite (Mg2SiO4) rather than enstatite (MgSiO3) or other silicate compositions. We confirm that high mass-loss rates should produce more crystalline material, and show why this should be dominated by forsterite. The presence of Mg2SiO4 glass suggests that another factor (possibly C/O) is critical in determining astromineralogy. Correlation between crystallinity, mass-loss rate, and initial stellar mass suggests that only the most massive AGB stars contribute significant quantities of crystalline material to the interstellar medium, resolving the conundrum of its low crystallinity.
A soluble polymer-bound approach to the Sharpless catalytic asymmetric dihydroxylation (AD) reaction: Preparation and application of a [(DHQD)2PHAL-PEG-OMe] ligand

Abstract The synthesis of a soluble polymer-bound (DHQD)2PHAL ligand 1 and its successful application in the catalytic asymmetric dihydroxylation reaction are described. The results highlight that the soluble polymer-bound ligand approach offers all the benefits associated with insoluble supports but with the key advantages of increased reactivity and enantioselectivity inherent with solution-phase methodology.
Jacobi cohomology, local geometry of moduli spaces, and hitchin connections

We develop some cohomological tools for the study of the local geometry of moduli and parameter spaces in complex Algebraic Geometry. Notably, we develop canonical formulae for the differential operators of arbitrary order and their natural action on suitable `natural' modules (for example, functions); in particular, we obtain a formula, in terms of the moduli problem, for the Lie bracket of vector fields on a moduli space. As an application, we obtain another construction and proof of flatness for the familiar KZW or Hitchin connection on moduli spaces of curves.
Implicit boundary conditions for the solution of the parabolized Navier-Stokes equations for supersonic flows

A fully implicit set of boundary conditions is developed for the solution of the parabolized Navier-Stokes equations for supersonic flow in two dimensions. Shock fitting is employed at the shock and the body has no-slip and specified temperature conditions. A specified heat transfer condition at the wall can be handled in a similar manner. In addition, the shock location is advanced in space in a fully implicit manner by utilizing the Rankine-Hugoniot conditions along with global conservation of mass.
Solar energy in providing for alternate lifestyles

Abstract Exploitation of cheap and abundant reservoirs of fossil fuels, we know, has permitted some cultures to develop a lifestyle and standard of living which depletes natural resources. To reduce the severity of this draw-down, a concept has been developed which combines the best of modern technology and the experience of more primitive societies in producing a residential option which is low in environmental impact as well as aesthetically attractive. An educational demonstration of this residential concept is to be developed on a six-acre plot 25 miles southwest of Chicago. This paper will identify the design and usage features which enable the occupants to collect all their residential energy from the sun, to receive all their water from natural rainfall, and to recycle their wastes for return to a horticultural plot which will provide most of their food. This paper will also discuss the adaptability of this concept to a variety of situations through modifications or abbreviations.
Quantum automata and quantum grammars

Abstract To study quantum computation, it might be helpful to generalize structures from language and automata theory to the quantum case. To that end, we propose quantum versions of finite-state and push-down automata, and regular and context-free grammars. We find analogs of several classical theorems, including pumping lemmas, closure properties, rational and algebraic generating functions, and Greibach normal form. We also show that there are quantum context-free languages that are not context-free, so QCFL ≠ CFL .
The Probabilistic Program Dependence Graph and Its Application to Fault Diagnosis

This paper presents an innovative model of a program's internal behavior over a set of test inputs, called the probabilistic program dependence graph (PPDG), which facilitates probabilistic analysis and reasoning about uncertain program behavior, particularly that associated with faults. The PPDG construction augments the structural dependences represented by a program dependence graph with estimates of statistical dependences between node states, which are computed from the test set. The PPDG is based on the established framework of probabilistic graphical models, which are used widely in a variety of applications. This paper presents algorithms for constructing PPDGs and applying them to fault diagnosis. The paper also presents preliminary evidence indicating that a PPDG-based fault localization technique compares favorably with existing techniques. The paper also presents evidence indicating that PPDGs can be useful for fault comprehension.
Coordinated lidar and TIMED observations of the quasi-two-day wave during August 2002 - 2004 and possible quasi-biennial oscillation influence

Abstract The Colorado State University sodium lidar, located in Fort Collins, CO (41N, 105W), is capable of both daytime and nighttime operations and has conducted a number of continuous multiple-day observational campaigns over the past few years. Three such campaigns, lasting between 80 and 90 h, were conducted during August 2002–2004 when mesospheric winds and temperature observations were collected simultaneously. These data were processed to extract the vertical structure and temporal evolution of the quasi-two-day wave, which was found to be significant in the power spectra. The quasi-two-day wave in temperature, zonal wind and meridional wind was analyzed for each year, indicating that the wave activity in 2003 was weaker than the other two years. Concurrent TIMED/SABER (2002–2004) and TIMED/TIDI observations (2004) in August were also processed. The SABER temperature shows a quasi-two-day wave with a dominant westward propagating zonal wavenumber four (s = −4) component in 2002 and 2004 but not in 2003. Analysis of the TIDI winds in August 2004 also indicates significant quasi-two-day wave activity, with the zonal wavenumber three and four components of comparable strength. The results of this coordinated ground-based lidar and TIMED satellite observations during August are presented. The possible influence of quasi-biennial oscillation on the inter-annual variability of the quasi-two-day wave is investigated.
Exact solution of a boundary conformal field theory

Abstract We study the conformal field theory of a free massless scalar field living on the half-line with interactions introduced via a periodic potential at the boundary. An SU(2) current algebra underlies this system and the interacting boundary state is given by a global SU(2) rotation of the left-moving fields in the zero-potential (Neumann) boundary state. As the potential strength varies from zero to infinity, the boundary state interpolates between the Neumann and the Dirichlet values. The full S-matrix for scattering from the boundary, with arbitrary particle production, is explicitly computed. To maintain unitarity, it is necessary to attribute a hidden discrete “soliton” degree of freedom to the boundary. The same unitarity puzzle occurs in the Kondo problem, and we anticipate a similar solution.
Seasonal change in the deep atmosphere of Uranus

Abstract We present high-resolution radio maps of Uranus, made from data collected in 1994 at wavelengths of 2 and 6 cm, which show large-scale changes occurring deep and rapidly in the troposphere. Brightness features in these maps are significantly different from those observed throughout the 1980's. These differences are not due to the changing viewing geometry, but result from atmospheric changes in the 5 to 50 bar region. All the observations show strong latitudinal variations in absorber abundance and/or temperature, causing the South Pole to appear brighter than lower latitudes. The transition between bright pole and darker latitudes is always near −45°, but between 1989 and 1994 the contrast between the regions increased significantly. This suggests that the large-scale circulation in the upper 50 bars of the uranian Southern Hemisphere changed. Older, disk-averaged microwave observations have suggested that seasonal variability occurs, but these new maps are the first to provide detailed timing and location information which can be used to test dynamical models.
Results of Argon Laser Photocoagulation in Presumed Ocular Histoplasmosis

We performed argon laser photocoagulation on 31 eyes of 30 patients with presumed ocular histoplasmosis. Nineteen of 25 eyes (76%) with neovascular membranes 0.25 disk diameter or further from the fovea had 6/12 (20/40) or better vision after an average follow-up period of 20 months. Twenty-two of these eyes (88%) had the same or improved visual acuity during this period. When compared to a similar group of untreated eyes, the apparent advantage of photocoagulation in preserving visual acuity was not statistically significant.
Computation of cusp singularities for operator equations and their discretizations

We discuss the direct calculation of cusp singularities as solutions of a minimally augmented defining system, which is nonsingular under the canonical cusp conditions. The underlying operator equation may have any finite Fredholm index, and bounds on the discretization error are derived for the case of projection methods.
A natural orbital method for the electron momentum distribution in matter

Abstract A variational method for many-electron system is applied to momentum distribution calculations. The method uses a generating two-electron geminal and the amplitudes of the occupancies of one particle natural orbitals as variational parameters. It introduces correlation effects beyond the free fermion nodal structure.
A convenient synthesis of d-myo-inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) and l-myo-inositol 1,4,5-trisphosphate (Ins(3,5,6)P3)

An efficient synthesis of an optically active inositol derivative that is a precursor to D-myo-inositol 1,4,5-trisphosphate (Ins(1,4,5)P3, (-)) is described. Crystallization of the diastereomers of (+/-)-1-O-[(+)-menthoxycarbonyl]-6-O-benzyl-2,3:4,5-di-O-isopropyl idene-myo- inositol diastereomers from methanol gives only one diastereomer. Alkaline hydrolysis gives the useful inositol derivative (-)-6-O-benzyl-2,3:4,5-di-O-isopropylidene-myo-inositol. Likewise, crystallization of the diastereomers of (+/-)-3-O-[(-)-menthoxycarbonyl]-4-O-benzyl-1,2:5,6-di-O-isopropyl idene-myo- inositol from methanol gave a pure compound which could be hydrolyzed to give (+)-4-O-benzyl-1,2:5,6-di-O-isopropylidene-myo-inositol, a precursor to D-myo-inositol 3,5,6-trisphosphate (Ins(3,5,6)P3,(+)). The ease with which these enantiomerically pure inositol derivatives were isolated may facilitate the synthesis of more complex inositol phosphate derivatives such as D-myo-inositol 1,3,4,5-tetrakisphosphate.
Model of rapid gastrointestinal transit in dogs: effects of muscarinic antagonists and a nitric oxide synthase inhibitor

Abstract Our aims were to establish a canine model of rapid gastrointestinal transit, and to test the effects of muscarinic receptor antagonists (atropine, pirenzepine, AF-DX116, and darifenacin), and an NOS inhibitor, l-nitro-N-arginine (l-NNA) in this model. For gastric emptying and small bowel transit,99mTc-labelled DTPA were added to a meal of skimmed milk (236 mL) that contained 2.4 g of magnesium hydroxide. Regional colonic transit was measured by111In-labelled beads placed in a capsule that released isotope in the proximal colon. Scintiscans were taken at regular intervals and indices of transit were calculated. Drugs were administrated intravenously. Gastric emptying, small bowel and colonic transit were rapid. Atropine and darifenacin (a selective M3antagonist) delayed gastric emptying and colonic transit, the selective M1and M2muscarinic antagonists did not. The muscarinic blockers did not slow small bowel transit. l-NNA delayed small bowel and colonic transit but did not slow gastric emptying. A model suitable for the preclinical study of antidiarrhoeals was established. M3receptors are important in the control of gastric emptying and colonic transit, and NOS inhibition slowed small bowel and colonic transit.
Thermodynamics and phase transitions of electrolytes on lattices with different discretization parameters

Lattice models are crucial for studying thermodynamic properties in many physical, biological and chemical systems. We investigate the lattice restricted primitive model (LRPM) of electrolytes with different discretization parameters in order to understand thermodynamics and the nature of phase transitions in systems with charged particles. A discretization parameter is defined as a number of lattice sites that can be occupied by each particle, and it allows one to study the transition from the discrete picture to the continuum-space description. Explicit analytic and numerical calculations are performed using the lattice Debye–Huckel approach, which takes into account the formation of dipoles, the dipole–ion interactions and correct lattice Coulomb potentials. The gas–liquid phase separation is found at low densities of charged particles for different types of lattices. The increase in the discretization parameter lowers the critical temperature and the critical density, in agreement with Monte Carlo com...
Analysis of energy consumption for multiple object identification system with active RFID tags

Radio frequency identification (RFID) systems are very effective for identifying objects. Existing published works focus on designing efficient collision resolution protocols for the tag identification problem in RFID systems with passive RFID tags. However, advances in low-cost and low-power sensing technologies will make active RFID tags more popular and affordable in the near future. In multiple object identification systems with active tags, the tags are designed for extremely low-cost large-scale applications such that battery replacement is not feasible. This imposes a critical energy-constraint on the communication protocols used in these systems. In this paper, we analyze energy consumption and identification times for several protocols. The objective is to decrease energy consumption of tags by reducing both the total identification time and the total active time. Copyright © 2007 John Wiley & Sons, Ltd.
NOWHERE-ZERO HARMONIC SPINORS AND THEIR ASSOCIATED SELF-DUAL 2-FORMS

Let M be a closed oriented 4-manifold, with Riemannian metric g, and a -structure induced by an almost-complex structure ω. Each connection A on the determinant line bundle induces a unique connection ∇A, and Dirac operator on spinor fields. Let be the natural squaring map, taking self-dual spinors to self-dual 2-forms. In this paper, we characterize the self-dual 2-forms that are images of self-dual spinor fields through σ. They are those α for which (off zeros) c1(α)=c1(ω), where c1(α) is a suitably defined Chern class. We also obtain the formula: . Using these, we establish a bijective correspondence between: {Kahler forms α compatible with a metric scalar-multiple of g, and with c1(α)=c1(ω)} and {gauge classes of pairs (φ,A), with ∇Aφ=0}, as well as a bijective correspondence between: {Symplectic forms α compatible with a metric conformal to g, and with c1(α)=c1(ω)} and {gauge classes of pairs (φ,A), with , and ℝ=0, and φ nowhere-zero}.
Genetic Exceptionalism and Legislative Pragmatism

Genetic-specific nondiscrimination laws have been enacted in most states, but the laws are ineffective and increase the stigma of genetic conditions. Whether these laws are better than no new legislation depends on their consequences and a recognition of their limitations.
Predictors of prosthetic graft infection after infrainguinal bypass.

Background Some patients require major leg amputation after lower-extremity prosthetic bypass for graft occlusion or failure of wound healing, despite a patent graft. Amputation above or below the knee was hypothesized to increase susceptibility to prosthetic graft infection in the ipsilateral extremity. Study Design All patients undergoing implantation of prosthetic infrainguinal arterial bypass grafts identified from a vascular surgical registry during a 12-year period were reviewed. Patient demographic data, comorbid conditions, and operative details were evaluated as risk factors, with graft infection among the primary outcomes of interest. Results Prosthetic graft infection occurred in 25 of 141 (18%) infrainguinal grafts and occurred most frequently after major amputation (41% versus 6%; odds ratio [OR] = 12; 95% CI, 4.1 to 34) or early reoperation after initial grafting (70% versus 16%; OR=11; 95% CI, 1.9 to 63). Risk was highest after amputation within 4 weeks of bypass (70% versus 32%; OR=5.0; 95% CI, 1.1 to 23). Graft thrombosis (84% versus 39%; OR=8.3; 95% CI, 2.7 to 26) and presence of gangrene (52% versus 23%; OR=3.6; 95% CI, 1.5 to 8.7) also increased infection risk. Independent predictors for development of graft infection were identified by stepwise regression analysis to be amputation (p Conclusions Amputation increases risk of prosthetic graft infection, especially when performed early or after failed revascularization. Consideration should be given to partial or complete removal of a prosthetic graft above the level of the amputation under these conditions.
Current‐Driven Excitations in Magnetic Multilayers: A Brief Review

In 1996, Berger and Slonczewski independently predicted that a large enough spin–polarized dc current density sent perpendicularly through a ferromagnetic layer could produce magnetic excitations (spin–waves) or reversal of magnetization (switching). In the past few years, both current-driven switching and current-driven excitation of spin–waves have been observed. The switching is of potential technological interest for direct ‘writing’ of magnetic random access memory (MRAM) or magnetic media. The spin–wave generation could provide a new source of dc generated microwave frequency radiation. We will describe what has been learned experimentally about these two related phenomena, and some models being tested to explain these observations. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Modeling quark-hadron duality for relativistic, confined fermions

We discuss a model for the study of quark-hadron duality in inclusive electron scattering based on solving the Dirac equation numerically for a scalar confining linear potential and a vector color Coulomb potential. We qualitatively reproduce the features of quark-hadron duality for all potentials considered, and discuss similarities and differences to previous models that simplified the situation by treating either the quarks or all particles as scalars. We discuss the scaling results for PWIA and FSI, and the approach to scaling using the analog of the Callan-Gross relation for y-scaling.
Tailoring atropisomeric maleimides for stereospecific [2 + 2] photocycloaddition--photochemical and photophysical investigations leading to visible-light photocatalysis.

Atropisomeric maleimides were synthesized and employed for stereospecific [2 + 2] photocycloaddition. Efficient reaction was observed under direct irradiation, triplet-sensitized UV irradiation, and non-metal catalyzed visible-light irradiation, leading to two regioisomeric (exo/endo) photoproducts with complete chemoselectivity (exclusive [2 + 2] photoproduct). High enantioselectivity (ee > 98%) and diastereoselectivity (dr > 99:1%) were observed under the employed reaction conditions and were largely dependent on the substituent on the maleimide double bond but minimally affected by the substituents on the alkenyl tether. On the basis of detailed photophysical studies, the triplet energies of the maleimides were estimated. The triplet lifetimes appeared to be relatively short at room temperature as a result of fast [2 + 2] photocycloaddition. For the visible-light mediated reaction, triplet energy transfer occurred with a rate constant close to the diffusion-limited value. The mechanism was established ...
A proof of the set-theoretic version of the salmon conjecture

Abstract We show that the irreducible variety of 4 × 4 × 4 complex valued tensors of border rank at most 4 is the zero set of polynomial equations of degree 5 (the Strassen commutative conditions), of degree 6 (the Landsberg–Manivel polynomials), and of degree 9 (the symmetrization conditions).
Speech language pathologists' opinions of constraint-induced language therapy.

AbstractBackground: Constraint-induced language therapy (CILT) has received recent attention as a possible intervention to improve expressive language in people with nonfluent aphasia. Difficulties have been reported with the practical implementation of constraint-induced movement therapy due to its intensive treatment parameters. It remains unknown whether similar challenges may exist with CILT. Objective: To determine the opinions of speech-language pathologists (SLPs) about CILT for people with nonfluent aphasia. Method and Procedures: One hundred sixty-seven SLPs completed an electronic survey assessing their opinions of various aspects of CILT. Outcomes and Results: Over 60% of participants felt that people with aphasia would be very unlikely or somewhat unlikely to adhere to CILT. The majority felt that people with aphasia would hold high or moderate concerns with the number of hours spent in therapy (high, 41.8%; moderate, 31.4%), the number of days spent in therapy (high, 44.4%; moderate, 24.8%), ...
NONLINEAR SIMULATIONS OF THE HEAT-FLUX-DRIVEN BUOYANCY INSTABILITY AND ITS IMPLICATIONS FOR GALAXY CLUSTERS

In low-collisionality plasmas heat flows almost exclusively along magnetic field lines and the condition for stability to convection is modified from the standard Schwarzschild criterion. We present local two- and three-dimensional simulations of a new heat-flux-driven buoyancy instability (the HBI) that occurs when the temperature in a plasma decreases in the direction of gravity. We find that the HBI drives a convective dynamo that amplifies an initially weak magnetic field by a factor of ~20. In simulations that begin with the magnetic field aligned with the temperature gradient, the HBI saturates by rearranging the magnetic field lines to be almost purely perpendicular to the initial temperature gradient. This magnetic field reorientation results in a net heat flux through the plasma that is less than 1% of the field-free (Spitzer) value. We show that the HBI is likely to be present in the cool cores of clusters of galaxies between ~0.1-100 kpc, where the temperature increases outward. The saturated state of the HBI suggests that inward thermal conduction from large radii in clusters is unlikely to solve the cooling flow problem. Finally, we also suggest that the HBI may contribute to suppressing conduction across cold fronts in galaxy clusters.