cssi/SciSciGPT-SciSciNet huggingface dataset:
Analysis of Magnetotail Flux Ropes with Strong Core Fields : ISEE 3 Observations

A set of nineteen specific magnetic field structures in distant (≈220 Re) ISEE 3 magnetotail plasma sheet observations are analyzed. These were initially chosen on the basis of strong central (core) fields compared to nearby lobe field strengths by Slavin et al. (1995); the selection criteria by design did not include field directional changes. This present study starts with the same set of events as Slavin et al. Further discrimination is done on the basis of how well the signatures are fit by a force-free flux rope field model. This model was earlier applied successfully to magnetotail flux ropes where GEOTAIL field data were used. In general the ISEE 3 study yields average properties for the flux ropes that are similar to those of the GEOTAIL study, which had only about half the number of events, and hence, it strongly supports that earlier study. One difference in the results of these studies, however, is the greater longitudinal spread of rope-axes in the present study, and this feature, related flux rope current systems, and other properties are discussed. The results of this study should provide rigid constraints on global models of tail current systems associated with tailward moving flux ropes related to substorms.
Studies of Lean Blowout in a Step Swirl Combustor

The design requirements of a modern gas turbine combustor are increasingly dictated by wide stability limits, short flame length, and uniform mixing. To achieve the best trade-off between these three factors, flame characteristics (length, shape, mixedness), lean blowout (LBO), and optimum combustor configuration should be investigated over a wide range of inner and outer air velocities, inner and outer vane angles, and co-versus counterswirl arrangements. Such an investigation was performed in a step swirl combustor (SSC) designed to simulate the fuel-air mixing pattern in a gas turbine combustor dome fitted with an airblast atomizer. It was found that an increase in the outer vane angle and a decrease in inner air velocity decreased the flame length. LBO was improved when outer flow swirl intensity was increased. An optimum hardware and velocity configuration for the SSC was found for inner swirl = 45 deg. outer swirl = 60 deg. coswirl direction, and inner air velocity = outer air velocity = 16 m/s. This optimum SSC configuration yielded: (i) low values of LBO, (ii) short flame length, (iii) uniformly mixed stable flame, and (iv) little or no variation in these characteristics over the range of operation of SSC. Finally, the co-versus counterswirlmore » arrangements and the operation of the optimized combustor configuration are discussed.« less
Gold Atoms Stabilized on Various Supports Catalyze the Water–Gas Shift Reaction

For important chemical reactions that are catalyzed by single-site metal centers, such as the water–gas shift (WGS) reaction that converts carbon monoxide and water to hydrogen and carbon dioxide, atomically dispersed supported metal catalysts offer maximum atom efficiency. Researchers have found that for platinum metal supported on ceria and doped ceria in the automobile exhaust catalyst, atomic Pt–Ox–Ce species are the active WGS reaction sites. More recently, preparations of gold at the nanoscale have shown that this relatively “new material” is an active and often more selective catalyst than platinum for a variety of reactions, including the WGS reaction. The activity of gold is typically attributed to a size effect, while the interface of gold with the support has also been reported as important for oxidation reactions, but exactly how this comes about has not been probed satisfactorily. Typical supported metal catalysts prepared by traditional techniques have a heterogeneous population of particles...
Information revelation and random entry in sequential ascending auctions

I develop an infinite-horizon model of a market in which new buyers and sellers arrive probabilistically. Upon arrival, each seller offers a single good for sale via an ascending auction. Buyers are endowed with private values and single-unit demand, and remain present on the market until they transact.I characterize a symmetric and efficient equilibrium for this game, accounting for the endogenous options created by the sequential nature of the market and the informational asymmetries introduced by new entrants. I then show the equivalence between the sequential ascending auction and the dynamic generalizations of the Vickrey-Clarke-Groves mechanism studied in [1, 2].
Protoplanet Dynamics in a Shear-dominated Disk

The velocity dispersion, or eccentricity distribution, of protoplanets interacting with planetesimals is set by a balance between dynamical friction and viscous stirring. We calculate analytically the eccentricity distribution function of protoplanets embedded in a cold, shear-dominated planetesimal swarm. We find a distinctly non-Rayleigh distribution with a simple analytical form. The peak of the distribution lies much lower than the rms value, indicating that while most of the bodies have similarly small eccentricities, a small subset of the population contains most of the thermal energy. We also measure the shear-dominated eccentricity distribution using numerical simulations. The numerical code treats each protoplanet explicitly and adds an additional force term to each body to represent the dynamical friction of the planetesimals. Without fitting any parameters, the eccentricity distribution of protoplanets in the N-body simulation agrees with the analytical results. This distribution function provides a useful tool for testing hybrid numerical simulations of late-stage planet formation.
On the reactivity of imidazole carbamates and ureas and their use as esterification and amidation reagents

Abstract The optimization, substrate scope, and mechanism of esterification and amidation of carboxylic acids mediated by imidazole-based reagents are discussed. The innate reactivity of carbonylimidazole reagents with a range of nucleophiles is also explored. New reagents developed for the synthesis of α,β-unsaturated esters are described, as are reagents for the preparation of tertiary amides directly from carboxylic acids.
Ultrahigh contrast and large-bandwidth thermal rectification in near-field electromagnetic thermal transfer between nanoparticles

We exploit the unique properties of electromagnetic waves in nanophotonic structures to enhance the capabilities for active control of electromagnetic thermal transfer at nanoscale. We show that the near-field thermal transfer between two nanospheres can exhibit thermal rectification effect with very high contrast, and with large operating bandwidth. In this system, the scale invariance properties of the resonance modes result in a large difference in the coupling constants between relevant modes in the forward and reverse scenarios. Such a difference in coupling constants provides a new mechanism for thermal rectification.
GeV and Higher Energy Photon Interactions in Gamma-Ray Burst Fireballs and Surroundings

We have calculated the opacities and secondary production mechanisms of high-energy photons arising in gamma-ray burst internal shocks, using exact cross sections for the relevant processes. We find that for reasonable choices of parameters, photons in the range of tens to hundreds of GeV may be emitted in the prompt phase. Photons above this range are subject to electron-positron pair production with fireball photons and would be absent from the spectrum escaping the gamma-ray burst. We find that, in such cases, the fireball becomes optically thin again at ultrahigh energies (PeV). On the other hand, for sufficiently large fireball bulk Lorentz factors, the fireball is optically thin at all energies. Both for γγ self-absorbed and optically thin cases, the escaping high-energy photons can interact with infrared and microwave background photons to produce delayed secondary photons in the GeV-TeV range. These may be observable with GLAST or at low redshifts with ground-based air Cerenkov telescopes. Detection of the primary prompt spectrum constrains the bulk Lorentz factor, while detection of delayed secondary gamma rays would provide a consistency check for the primary spectrum and the bulk Lorentz factor, as well as constraints on the intergalactic magnetic field strength.
The Synergy of Direct Imaging and Astrometry for Orbit Determination of Exo-Earths

The holy grail of exoplanet searches is an exo-Earth, an Earth mass planet in the habitable zone (HZ) around a nearby star. Mass is one of the most important characteristics of a planet and can only be measured by observing the motion of the star around the planet-star center of gravity. The planet's orbit can be measured either by imaging the planet at multiple epochs or by measuring the position of the star at multiple epochs by space-based astrometry. The measurement of an exoplanet's orbit by direct imaging is complicated by a number of factors. One is the inner working angle (IWA). A space coronagraph or interferometer imaging an exo-Earth can separate the light from the planet from the light from the star only when the star-planet separation is larger than the IWA. Second, the apparent brightness of a planet depends on the orbital phase. A single image of a planet cannot tell us whether the planet is in the HZ or distinguish whether it is an exo-Earth or a Neptune-mass planet. Third is the confusion that may arise from the presence of multiple planets. With two images of a multiple planet system, it is not possible to assign a dot to a planet based only on the photometry and color of the planet. Finally, the planet-star contrast must exceed a certain minimum value in order for the planet to be detected. The planet may be unobservable even when it is outside the IWA, such as when the bright side of the planet is facing away from us in a crescent phase. In this paper we address the question: Can a prior astrometric mission that can identify which stars have Earth-like planets significantly improve the science yield of a mission to image exo-Earths? In the case of the Occulting Ozone Observatory, a small external occulter mission that cannot measure spectra, we find that the occulter mission could confirm the orbits of ~4 to ~5 times as many exo-Earths if an astrometric mission preceded it to identify which stars had such planets. In the case of an internal coronagraph we find that a survey of the nearest ~60 stars could be done with a telescope half the size if an astrometric mission had first identified the presence of Earth-like planets in the HZ and measured their orbital parameters.
QCD instantons in vacuum and matter

Abstract The singlet coupling to the topological charge density in the instanton vacuum, causes the instantons and anti-instantons to be screened over distances of the order of 1 2 fm . Dilute instanton systems behave as a free gas, while dense instanton systems behave as a plasma. The free gas behaviour is favored by a density of 1 fm −4 . Owing to the Higgs mechanism, the η ′ mass is heavy (1100 MeV). The vacuum topological susceptibility is small (0.07 fm −4 ) and consistent with the QCD Ward identify. In the chiral limit, the singlet screening vanishes, leading to a four-dimensional plasma state with a temperature given by the nonet decay constant ƒ (90 MeV). The phase is Debye screened. In the presence of matter, the screening is quenched, and a Kosterlitz-Thouless transition may occur signaling the restoration of the U A (1) symmetry. We suggest to use the spatial asymptotics of the static topological charge correlator together with the topological susceptibility to probe the interplay between the U A (1) restoration and the chiral restoration in finite temperature QCD. The relevance of these results to the bulk thermodynamics in the instanton vacuum is discussed.
Parametric Trends in the Flutter of Advanced Turboprops

The parametric trends in the aeroelastic behavior of an advanced turboprop were experimentally investigated using a subvelocity-scaled testing procedure. A 2-ft-dia subvelocity-scaled model was constructed and its flutter behavior was favorably correlated to that of a full-velocity-scaled UnDucted Fan model for which a flutter point had been documented
Interfacing computers for the physically handicapped: a review of international approaches

The computer has shown great promise for expanding educational and occupational opportunities for severely handicapped individuals. The greatest obstacle facing these individuals today is that they are unable to access computers through traditional keyboards or other types of terminals. This paper describes the three basic techniques which have been successfully used to allow the severely handicapped to communicate with other people and with their environment. A review of over 25 various approaches which have been developed around the world is presented, including a comprehensive bibliography of available information.
Trade as a threshold variable for multiple regimes

Abstract This paper employs the data-sorting method developed by Hansen [Econometrica 68 (2000) 575] which allows the data to endogenously select regimes using different variables. It is shown that openness, as measured by the trade share to GDP, is a threshold variable that can cluster middle-income countries into two distinct regimes that obey different statistical models. Our result suggests that openness may not be as crucial in the growth process of low and high-income countries but it is instrumental in identifying middle-income countries into high and low-growth groups.
Typical Real Ranks of Binary Forms

We prove a conjecture of Comon and Ottaviani that typical real Waring ranks of bivariate forms of degree d take all integer values between $\lfloor \frac{d+2}{2}\rfloor$ and d. That is, we show that for all d and all $\lfloor \frac{d+2}{2}\rfloor \leq m \leq d$ there exists a bivariate form f such that f can be written as a linear combination of mdth powers of real linear forms and no fewer, and additionally all forms in an open neighborhood of f also possess this property. Equivalently we show that for all d and any $\lfloor \frac{d+2}{2}\rfloor \leq m \leq d$ there exists a symmetric real bivariate tensor t of order d such that t can be written as a linear combination of m symmetric real tensors of rank 1 and no fewer, and additionally all tensors in an open neighborhood of t also possess this property.
Contrast resolution of a kinestatic charge detector

The low-contrast imaging capabilities of the kinestatic charge detector (KCD), a gas-filled detector for slot-beam digital radiography, are examined and compared with those of conventional x-ray detectors. Monte Carlo modeling is used to investigate detector efficiency, detected contrast, and scatter rejection. Three indices for detector performance are developed. The high-frequency limit to DQE shows the effects of secondary photon reabsorption in the detector. It corresponds to zero-frequency DQE, and is equally simple to model computationally. The contrast factor links DQE with the task-dependent DQE of Tapiovaara and Wagner by relating signal-to-noise ratio (SNR) to contrast-to-noise ratio (CNR). Detected scatter reduces the square of SNR by a factor equal to the detected primary fraction for noise variance. Highly loaded KCDs are seen to absorb photons more efficiently than conventional detectors. Krypton suffers less than xenon from DQE losses at high frequency. Contrast effects moderate the DQE advantages of KCDs, and detected CNR may even decline with increasing detector loading. KCDs regain their advantage when scatter effects are included. X-ray beam utilization is sufficient for KCDs to match or exceed the CNR of conventional systems, at lower patient dose, for all cases studied except for the thickest patients with the lowest energy beams. Further improvements are expected from changes in KCD system design.
Superconducting dome and crossover to an insulating state in [Tl4]Tl1−xSnxTe3

The structural, superconducting, and electronic phase diagram of [Tl4]Tl1−xSnxTe3 is reported. Magnetization and specific heat measurements show bulk superconductivity exists for 0 ≤ x ≤ 0.4. Resistivity measurements indicate a crossover from a metallic state at x = 0 to a doped insulator at x = 1. Universally, there is a large non-Debye specific heat contribution, characterized by an Einstein temperature of θE ≈ 35 K. Density functional theory calculations predict x = 0 to be a topological metal, while x = 1 is a topological crystalline insulator. The disappearance of superconductivity correlates with the transition between these distinct topological states.
Irradiated Herbig-Haro Jets in the Orion Nebula and near NGC 1333

We report the discovery of a dozen Herbig-Haro jets illuminated by the Lyman continuum (λ < 912 A) and/or softer far-ultraviolet (912 < λ < 2000 A) radiation fields of nearby high-mass stars. Five irradiated outflows lie in the outer parts of the Orion Nebula (HH 502-506), and seven lie near the reflection nebula NGC 1333 in the Perseus molecular cloud (HH 333-336 and HH 497-499). These stellar outflows are powered by optically visible low-mass young stars that suffer relatively low extinction and seem not to be embedded within opaque cloud cores. We propose that the UV radiation field has eroded residual material left over from their formation on a timescale short compared to the ages of these star-forming regions. Many of the irradiated jets exhibit unusual C-shaped symmetry. In the outskirts of the Orion Nebula, most irradiated jets appear to bend away from the core of the nebula. On the other hand, in NGC 1333, the C-shaped jets tend to bend back toward the cluster center. Jet bending in the Orion Nebula may be dominated by either the outflow of material from the nebular core or by the rocket effect pushing on the irradiated portion of a mostly neutral jet beam. But in NGC 1333, jet bending may indicate that the source stars have been ejected from the cluster core. Many irradiated jets are asymmetric with one beam much brighter than the other. When fully photoionized, irradiated jets may provide unique insights into the physical conditions within outflows powered by young stars, permitting the determination of the density and location of stellar ejecta even in the absence of shocks. We present a model for the photoionization of these outflows by external radiation fields and discuss possible mechanisms for producing the observed asymmetries. In particular, we demonstrate that the UV radiation field may alter the amount of cloud material entrained by the jet. Radiation-induced variations in mass loading and beam heating can produce differences in the beam velocities and spreading rates, which in turn determine the surface brightness of the radiating plasma. In a bipolar irradiated jet in which both beams have the same mass-loss rate and opening angle, the slower beam will appear brighter at a given distance from the source. On the other hand, if both beams spread orthogonal to the jet propagation direction with the same speed (e.g., both beams have the same internal sound speed or shocks with similar physical conditions), the faster beam will appear brighter at the same distance from the source. Thus, depending on the parameters, either the faster or slower beam of a jet can be brighter. Finally, we report the discovery of some large-scale bow shocks that face the core of the Orion Nebula and surround visible young stars. These wind-wind collision fronts provide further evidence for a large-scale mass flow originating near the nebular core.
Computing convolutions by reciprocal search

In this paper we show how certain geometric convolution operations can be computed efficiently. Here "efficiently" means that our algorithms have running time proportional to the input size plus the output size. Our convolution algorithms rely on new optimal solutions for certain reciprocal search problems, such as finding intersections between "blue" and "green" intervals, and overlaying convex planar subdivisions.
The role of rock weathering in the phosphorus budget of terrestrial watersheds

Residual soils (saprolites) developed on crystalline rocks appear to form by an essentially isovolumetric process (i.e. without dilation or compaction). Isovolumetric geochemical analysis of a suite of saprolite samples developed on a common parent rock can be used to estimate the relative rates of long-term losses of P and Si during weathering. Using the export of dissolved Si in rivers as a weathering index, one can then estimate the rate of P release due to chemical weathering by means of the P-Si loss ratio in saprolite. For three basins where data are available (Liberty Hill, SC; Amazon River, Brazil: Rio Negro, Brazil) estimated P weathering release rates are 163, 457, and 242 moles P km−2 yr−1 respectively. These compare to precipitation inputs of 684, 700 and 630 moles P km−2 yr−1 and total river exports of 256, 4490 and 820 moles P km−2 yr−1, respectively. The Rio Negro shows a near perfect balance between the input of P via precipitation and chemical weathering and the riverine output of dissolved and suspended P. This system, however, raised the unsolved problem of the source that supports the atmospheric P input.
Structural Model of Head Start Classroom Quality.

Abstract The purpose of this research study was to develop, test, and validate a model that identifies the characteristics and beliefs of teachers and aides, and the classroom structural dimensions associated with Head Start classroom quality. The quality of classroom teaching practices was collected using the Assessment Profile for Early Childhood Programs: Research Version. Classroom structural characteristics were collected by observers. Teachers and teacher aides completed three self-report instruments: Teacher Beliefs Scale, Instructional Activities Scale, and Family Involvement Survey. Data analyses were conducted using structural equation modeling with the Lisrel VII computer program. The model was tested with Year 1 classroom level data and validated with Year 2 data. Education Level was shown to directly affect Inappropriate Beliefs, which impacted Inappropriate Instructional Activities, which influenced Classroom Quality. Neither Education Level nor Teacher Beliefs had direct effects on Classroom Quality, but they had indirect effects through Instructional Activities. Classroom Structure was associated directly with Quality. Education Level and Classroom Quality were associated directly with Attitudes Toward Families.
Wavelength aware receiver for enhanced 2D OCDMA system performance

A novel receiver for two-dimensional (2D) optical code division multiple access (OCDMA) which utilises the wavelength information of the codes to provide enhanced performance than the regular receiver is presented. The performance improvement increases with the number of wavelengths. Maximal spectral efficiency is doubled, for carrier-hopping prime codes.
Equilibria in topology control games for ad hoc networks

We study topology control problems in ad hoc networks where network nodes get to choose their power levels in order to ensure desired connectivity properties. Unlike most other work on this topic, we assume that the network nodes are owned by different entities, whose only goal is to maximize their own utility that they get out of the network without considering the overall performance of the network. Game theory is the appropriate tool to study such selfish nodes: we define several topology control games in which the nodes need to choose power levels in order to connect to other nodes in the network to reach their communication partners while at the same time minimizing their costs. We study Nash equilibria and show that-among the games we define-these can only be guaranteed to exist if each network node is required to be connected to all other nodes (we call this the STRONG CONNECTIVITY GAME). For a variation called CONNECTIVITY GAME, where each node is only required to be connected (possibly via intermediate nodes) to a given set of nodes, we show that Nash equilibria do not necessarily exist. We further study how to find Nash equilibria with incentive-compatible algorithms and compare the cost of Nash equilibria to the cost of a social optimum, which is a radius assignment that minimizes the total cost in a network where nodes cooperate. We also study variations of the games; one where nodes not only have to be connected, but k-connected, and one that we call the REACHABILITY GAME, where nodes have to reach as many other nodes as possible, while keeping costs low. We extend our study of the STRONG CONNECTIVITY GAME and the CONNECTIVITY GAME to wireless networks with directional antennas and wireline networks, where nodes need to choose neighbors to which they will pay a link. Our work is a first step towards game-theoretic analyses of topology control in wireless and wireline networks.
Streaming Algorithms for Extent Problems in High Dimensions

We present (single-pass) streaming algorithms for maintaining extent measures of a stream S of n points in $\mathbb{R} ^{d}$ . We focus on designing streaming algorithms whose working space is polynomial in d (poly(d)) and sub-linear in n. For the problems of computing diameter, width and minimum enclosing ball of S, we obtain lower bounds on the worst-case approximation ratio of any streaming algorithm that uses poly(d) space. On the positive side, we introduce the notion of blurred ball cover and use it for answering approximate farthest-point queries and maintaining approximate minimum enclosing ball and diameter of S. We describe a streaming algorithm for maintaining a blurred ball cover whose working space is linear in d and independent of n.
A discrete spatial representation for lateral motion stereo

A simple procedure generates the complete minimum depth surface description of a three-dimensional scene that is consistent with a series of images from a laterally translating camera. The internal representation is a discrete map of intervening empty space between the camera and visible surfaces that is the result of occlusion and surface brightness constraints. The effectiveness of this algorithm is demonstrated on real and synthetic test images.
Electrochemical behavior of RuTi

Abstract The electrochemical properties of RuTi alloy in acidic solution have been investigated by means of steady-state polarization measurements and cyclic voltammetry. The resolved current-potential profiles for the formation/reduction of surface oxides and the deposition/dissolution of H at a RuTi electrode are basically similar to those at an elemental-Ru electrode. However, whereas the oxygen-evolution and Ru-corrosion reactions occur at nearly the same potential on elemental Ru, these reactions are well resolved on RuTi alloy; the Ru-corrosion reaction is shifted anodically by about 340 mV. RuTi alloy does not catalyze the methanol-oxidation reaction; it forms a hydride on cycling negative of the normal hydrogen potential. Although hydride formation appears to suppress the hydrogen evolution reaction, nevertheless the hydrogen-evolution activity remains relatively high. Interpretation of this behavior has been made with a model that involves a two-step oxidation of the alloy surface; the second step involves the migration of metal atoms as cation species to form a gelatinous layer of octahedrally coordinated cations and the inhibition of RuO 4 formation by more basic RuOM bridges.
Probing spontaneous CP-violation in supersymmetric models via B-decays

Abstract We study implications of spontaneous CP-violation in minimal susy models for CP-asymmetries in rare B, B -decays. In particular, we estimate characteristic values of the angles of the unitarity triangle and show that sizable CP-violating effects result from B− B mixing only. Significant deviations from the SM predictions are pointed out.
Controlling Factors for C—H Functionalization versus Cyclopropanation of Dihydronaphthalenes

Rhodium(II)-catalyzed reactions of vinyldiazoacetates with dihydronaphthalenes were systematically studied. These substrates underwent cyclopropanantion and/or the combined C−H activation/Cope rearrangement in good overall yield and with good diastereo- and enantiocontrol. The selectivity of these reactions was profoundly influenced by the nature of the chiral catalyst, the vinyldiazoacetate, and the dihydronaphthalene. The best combinations for achieving the highest selectivity in the cyclopropanation and the combined C−H activation/Cope rearrangement of 1,2-dihydronaphthalenes are methyl 2-diazopent-3-enoate (2a)/Rh2(S-DOSP)4 and methyl 3-(tert-butyldimethylsilyloxy)-2-diazopent-3-enoate (2b)/Rh2(S-PTAD)4. These combinations are very effective at enantiodivergent reactions of 1-methyl-1,2-dihydronaphthalenes.
The effect of systemic flurbiprofen on bone supporting dental implants

This article describes a study of the efficacy of the non-steroidal anti-inflammatory drug flurbiprofen in maintaining alveolar bone around mandibular root-form dental implants. The preliminary results indicate that, in appropriate doses, flurbiprofen may spare bone around such implants.
Are magnetic monopoles hadrons

The charges of magnetic monopoles are constrained to a multiple of 2{pi} times the inverse of the elementary unit electric charge. In the standard model, quarks have fractional charge, raising the question of whether the basic magnetic monopole unit is a multiple of 2{pi} or three times that. A simple lattice construction shows how a magnetic monopole of the lower strength is possible if it interacts with gluonic fields as well. Such a monopole is thus a hadron. This is consistent with the construction of magnetic monopoles in grand unified theories.
Evidence for a galactic origin of very short gamma ray bursts and primordial black hole sources

Abstract We systematically study the shortest time duration gamma ray bursts and find unique features that are best interpreted as sources of a galactic origin. There is a significant angular asymmetry and the V / V max distribution provides evidence for a homogeneous sources distribution. We review the arguments that primordial black hole evaporation can give such gamma ray bursts. The rate of events is consistent with a primordial black hole origin if we assume on enhanced local density, as are the other distributions. We suggest further tests of this hypothesis.
Electrostatic actuation of silicon optomechanical resonators

Cavity optomechanical systems offer one of the most sensitive methods for detecting mechanical motion using shifts in the optical resonance frequency of the optomechanical resonator. Presently, these systems are used for measuring mechanical thermal noise displacement or mechanical motion actuated by optical forces. Electrostatic capacitive actuation and detection have been shown previously for silicon micro electro mechanical resonators for application in filters and oscillators. Here, we demonstrate monolithic integration of electrostatic capacitive actuation with optical sensing using silicon optomechanical disk resonators and waveguides. The electrically excited mechanical motion is observed as an optical intensity modulation when the input electrical signal is at a frequency of 235MHz corresponding to the radial vibrational mode of the silicon microdisk.
Vector bundles over noncommutative nodal curves

We describe vector bundles over a class of noncommutative curves, namely, over noncommutative nodal curves of string type and of almost string type. We also prove that, in other cases, the classification of vector bundles over a noncommutative curve is a wild problem.
Synthesis of the spore photoproduct

Abstract The spore photoproduct was synthesized in seven steps from dihydrothymine and 5-formyluracil using a mixed Aldol coupling as the key bond forming step.
Stereoselective syntheses of quaternary substituted α-amino acids using oxazol-5-(4H)-ones

Quaternary α-amino acids play vital roles in protein and synthetic chemistries. Stereoselective access to such molecules has been an intensive focus of research in recent years, and new methods are continuously being explored. The present mini-review gives an overview of stereoselective syntheses of quaternary α-amino acids produced from racemic oxazolones.
Gd1.33Pt3(Al,Si)8 and Gd0.67Pt2(Al,Si)5: Two structures containing a disordered Gd/Al layer grown in liquid aluminum

Gd1.33Pt3Al8 was synthesized by the combination of Gd and Pt in excess liquid aluminum. Addition of silicon resulted in the incorporation of a small amount of this element into the material to form...
The Scattered Disk as the Source of the Jupiter Family Comets

The short-period Jupiter family comets (JFCs) are thought to originate in the Kuiper Belt; specifically, a dynamical subclass of the Kuiper Belt known as the "scattered disk" is argued to be the dominant source of JFCs. However, the best estimates from observational surveys indicate that this source may fall short by more than 2 orders of magnitude of the estimates obtained from theoretical models of the dynamical evolution of Kuiper Belt objects into JFCs. We reexamine the scattered disk as a source of the JFCs and make a rigorous estimate of the discrepancy. We find that the uncertainties in the dynamical models combined with a change in the size distribution function of the scattered disk at faint magnitudes (small sizes) beyond the current observational limit offer a possible but problematic resolution to the discrepancy. We discuss several other possibilities: that the present population of JFCs is a large fluctuation above their long-term average, that larger scattered disk objects tidally break up into multiple fragments during close planetary encounters as their orbits evolve from the trans-Neptune zone to near Jupiter, or that there are alternative source populations that contribute significantly to the JFCs. Well-characterized observational investigations of the Centaurs, objects that are transitioning between the trans-Neptune Kuiper Belt region and the inner solar system, can test the predictions of the non-steady state and the tidal breakup hypotheses. The classical and resonant classes of the Kuiper Belt are worth reconsideration as significant additional or alternate sources of the JFCs.
Placement algorithms for custom VLSI

Algorithms are presented for placement and for modifying existing placements to be used in channel routing solutions for custom VLSI layout. The placements are produced so as not to have channel routing order constraint cycles, which constitute a familiar problem for custom VLSI. The algorithms are based on mathematical results characterizing the structure of channel routing order constraints.
Fitting autoregressive trend stationary models with finite samples

Abstract Sims (Journal of Applied Econometrics, 6, 423–434) conjectured that the conditional maximum likelihood estimator of autoregressive trend stationary models of macroeconomic time series will tend to place initial observations relatively far from the estimated trend line, explaining early sample behavior as transient behavior as these series move from their extreme initial positions back toward the trend path. This can be misleading if the entire sample has been generated by the same data generating process and there is nothing unusual about the initial observations. We use Monte Carlo methods and the extended Nelson-Plosser data set to evaluate Sims' conjecture. We also study the behavior of the weighted symmetric estimator developed by Park and Fuller (Unpublished manuscript, 1993, Department of Statistics, Iowa State University, Ames, Iowa) as an estimator of autoregressive trend stationary models.
Time-dependent Ginzburg-Landau simulations of vortex guidance by twin boundaries

Abstract The driven motion of vortices in the presence of a planar defect is simulated by means of the time-dependent Ginzburg-Landau equations. Guided motion of the vortices, both internal and external to the twin boundary, is found to occur over a range of driving forces. Experimental transport data on a single crystal of YBa 2 Cu 3 O 7 are consistent with guided motion.
Zinc deficiency induces apoptosis via mitochondrial p53- and caspase-dependent pathways in human neuronal precursor cells.

Abstract Previous studies have shown that zinc deficiency leads to apoptosis of neuronal precursor cells in vivo and in vitro. In addition to the role of p53 as a nuclear transcription factor in zinc deficient cultured human neuronal precursors (NT-2), we have now identified the translocation of phosphorylated p53 to the mitochondria and p53-dependent increases in the pro-apoptotic mitochondrial protein BAX leading to a loss of mitochondrial membrane potential as demonstrated by a 25% decrease in JC-1 red:green fluorescence ratio. Disruption of mitochondrial membrane integrity was accompanied by efflux of the apoptosis inducing factor (AIF) from the mitochondria and translocation to the nucleus with a significant increase in reactive oxygen species (ROS) after 24 h of zinc deficiency. Measurement of caspase cleavage, mRNA, and treatment with caspase inhibitors revealed the involvement of caspases 2, 3, 6, and 7 in zinc deficiency-mediated apoptosis. Down-stream targets of caspase activation, including the nuclear structure protein lamin and polyADP ribose polymerase (PARP), which participates in DNA repair, were also cleaved. Transfection with a dominant-negative p53 construct and use of the p53 inhibitor, pifithrin-μ, established that these alterations were largely dependent on p53. Together these data identify a cascade of events involving mitochondrial p53 as well as p53-dependent caspase-mediated mechanisms leading to apoptosis during zinc deficiency.
Block loss reduction in ATM networks

Traditional approaches to guaranteeing Quality-of-Service (QoS) in ATM networks have focused on performance metrics such as cell loss probability, end-to-end cell delay and delay jitter. However, the block loss rate is a more meaningful metric for applications such as medical imaging and real-time video, and for high-level protocols such as IP which will use ATM as the transport mechanism. A block is defined as a group of consecutive ATM cells. For instance, a block may correspond to an IP datagram or to a macroblock within a medical image. A block loss occurs when a single cell from a block is lost. Consequently, we propose a technique for reducing block loss in ATM networks. Our method combines two well-studied approaches for minimizing the impact of information loss during transport over ATM networks which have been considered independently of each other in the past: priority-based cell discarding and forward error correction (FEC). We present a simple analysis which shows that our scheme could potentially reduce the block loss rate by several orders of magnitude for many cases of interest. We also formulate and solve a constrained optimization problem that can be used by a call admission control mechanism to determine optimal operating parameters. The analysis that we present is known to be somewhat optimistic since in reality cell losses in ATM-based networks are highly correlated. Consequently, we conduct extensive tests of the scheme via simulation. We also propose and study a buffer management algorithm which we call Adaptive Pushout (ADP) that accounts for correlations between cell losses. The ADP algorithm reduces block loss rates to nearoptimal levels. We consider further performance enhancements to the ADP policy that deliver excellent performance even under very heavy load. Practical implementation issues for the various schemes suggested in this paper are also addressed.
Laparoscopic Repair of Bowel Herniation Through Previous Cannula Insertion Sites

Operative laparoscopy frequently requires large cannulas below or above the umbilicus, which may result in unusual complications such as small bowel herniation through these insertion sites. Three women experienced small bowel herniation through cannula incision sites, either extraumbilically or paraumbilically, after major laparoscopic surgery. Two patients who had undergone laparoscopic myomectomy developed small bowel herniation through the 12-ram extraumbilical cannula site on postoperative days 7 and 8, respectively. In the first woman, the nontender, palpable, and reducible herniation healed spontaneously, with no episode of herniation during follow-up. The second patient required laparoscopic reduction of the herniated loop and repair of the fascial defect. The last woman had undergone laparoscopic-assisted vaginal hysterectomy and developed small bowel herniation through an unrecognized fasciat defect paraumbilicalty 3 days postoperatively. Intended repair by laparoscopy was changed to laparotomy due to extensive and incarcerated bowel herniation.
(LiNH2-MgH2): a viable hydrogen storage system

Abstract One of the problems related to the employment of hydrogen-based fuel cells for vehicular transportation is “on board” storage. Hydrogen storage in solids has long been recognized as one of the most practical approaches for this purpose. The capacity of existing storage materials is markedly below that needed for vehicular use. Recently Chen et al. [Nature 420 (21) (2002) 302; J. Phys. Chem. B 107 (2003) 10967] reported a lithium nitride/imide system, with a high capacity, 11.5 wt.%, however, its operating temperature and pressure are not satisfactory for vehicular application. In this research a new storage material has been developed, which is from the partial substitution of lithium by magnesium in the nitride/imide system. The plateau pressure of this new Mg-substituted system is about 30 bar and 200 °C with a H capacity of 4.5 wt.% and possibly higher. This is a very promising H-storage material for “on board” storage for vehicular applications.
A case of adoption of 25000 standards family establishing evaluation requirements in the audio-visual preservation context

The digital preservation want to guarantee accessible and usable over time digital audio-visual media content, regardless of the challenges of media failure and technological change. For this aim, the current technologies for digital audio-visual media preservation deal with complex technological, organizational, economic and rights-related issues. Ensuring the development and use of high-quality software could be a key factor for their success. The paper reports an experience matured inside the Presto4U project, with the contribution of the TATE Gallery. Aim of the experiment was the identification of preservation needs and corresponding preservation requirements in order to set up a quality evaluation process for used software tools making easy the technology transfer of research results into digital preservation environment. Using the framework of the international standards on software products quality, the evaluation requirements were mapped on the characteristics and sub-characteristics of a quality model and a specification of high-level software product quality evaluation plan has been obtained and presented.
Both Market and Hierarchy: An Incentive-System Theory of Hybrid Governance Forms

We create a taxonomy of hybrid governance forms and develop a formal theory that predicts when a given hybrid form will be efficient. Our model is unique in that we consider cross-task synergies in a multitask principal-agent model, where hybrid forms result as principals try to motivate cooperation among agents indirectly through incentives, ownership, and formal authority. We conclude with a discussion of other mechanisms that might also help us understand and predict hybrid governance forms.
Feature based sliding window technique for face recognition

Human beings are commonly identified by biometric schemes which are concerned with identifying individuals by their unique physical characteristics. The use of passwords and personal identification numbers for detecting humans are being used for years now. Disadvantages of these schemes are that someone else may use them or can easily be forgotten. Keeping in view of these problems, biometrics approaches such as face recognition, fingerprint, iris/retina and voice recognition have been developed which provide a far better solution when identifying individuals. A number of methods have been developed for face recognition. This paper illustrates employment of Gabor filters for extracting facial features by constructing a sliding window frame. Classification is done by assigning class label to the unknown image that has maximum features similar to the image stored in the database of that class. The proposed system gives a recognition rate of 96% which is better than many of the similar techniques being used for face recognition.
Inverting schema mappings

A schema mapping is a specification that describes how data structured under one schema (the source schema) is to be transformed into data structured under a different schema (the target schema). Although the notion of an inverse of a schema mapping is important, the exact definition of an inverse mapping is somewhat elusive. This is because a schema mapping may associate many target instances with each source instance, and many source instances with each target instance. Based on the notion that the composition of a mapping and its inverse is the identity, we give a formal definition for what it means for a schema mapping M′ to be an inverse of a schema mapping M for a class S of source instances. We call such an inverse an S-inverse. A particular case of interest arises when S is the class of all source instances, in which case an S-inverse is a global inverse. We focus on the important and practical case of schema mappings specified by source-to-target tuple-generating dependencies, and uncover a rich theory. When S is specified by a set of dependencies with a finite chase, we show how to construct an S-inverse when one exists. In particular, we show how to construct a global inverse when one exists. Given M and M′, we show how to define the largest class S such that M′ is an S-inverse of M.
Video compression with tunable complexity via flexible syntax design

Codecs such as H.264/AVC involve computationally intensive tasks that often prohibit the real-time implementation. It has been observed that the complexity of such video encoders can be tuned gracefully to a desired level through the use of a smaller set of macroblock types in mode decision and a lower motion vector precision in motion estimation. The rate-distortion performance, however, will be affected consequently. In this paper, we propose a flexible syntax mechanism (FSM) to tune the encoder complexity while maintaining a sufficient rate-distortion performance. The key idea inherit in the proposed FSM consists of two folds: first is the specification at the higher level of the bitstream syntax both the subset of macroblock types and the precision of motion vectors to be evaluated by the encoder, and second is the redesign of the entropy coders accordingly to effectively represent the selected macroblock types and the motion vectors. Since the entropy coding is optimized in terms of the bitrate consumption specifically for the subset of macroblock modes and the motion vector precision, the rate-distortion performance will be enhanced compared to the scenario where identical entropy codes are adopted regardless. Another advantage of our approach is the intrinsic scalability in complexity for the application of video encoding under different complexity constraints. The proposed approach may be considered for the next generation of video codecs with flexible complexity profiles.
When does interval coding occur

Abstract During the stationary portion of neuron's spiking response to a stimulus, the stimulus could be coded in the average rate and, more elaborately, in the statistics of the sequence of interspike intervals. We use information processing theory to explicitly define when interval coding occurs and quantify the coding gain beyond rate coding provided by the interval code. We explicitly find the interval distribution commensurate with average rate coding. When we analyzed optomotor neural responses recorded from the crayfish eye, we found little interval coding occurring despite stimulus-induced changes from a unimodal to a bimodal interval distribution.