cssi/SciSciGPT-SciSciNet huggingface dataset:
International Diversification and Analysts' Forecast Accuracy and Bias

We investigate the association between corporate international diversification and the accuracy and bias of consensus analysts' earnings forecasts. We find that greater corporate international diversification is associated with less accurate and more optimistic forecasts. Our results suggest that international diversification reflects unique dimensions of forecasting difficulty that are not captured in previously identified determinants. This evidence suggests that as firms become more geographically diversified, forecasting their earnings becomes more complex.
Percutaneous needle arteriography.

Successful arterial reconstructive surgery requires exact definition of the occlusive or aneurysmal process and the condition of the distal arterial tree. To define these two parameters, it is essential that arteriography be precise, yet it must be safe and reproducible. At our institution, we continue to utilize percutaneous needle arteriography because of its safety and excellent delineation of the vascular system. The purpose of this paper is to discuss our indications, techniques, and results of percutaneous arteriography for evaluation of peripheral arterial disease. During 1975, 1,253 percutaneous arteriograms were performed under general anesthesia by the surgical team. The techniques for carotid, vertebral (retrograde brachial), and femoral arteriograms, and translumbar aortograms will be reviewed. There were no deaths and only 8 (0.7%) complications. We believe that this technique provides an excellent method for good preoperative evaluation of the arterial system of the peripheral arteries and abdominal aorta.
Grid Embedding of 4-Connected Plane Graphs

A straight line grid embedding of a plane graph G is a drawing of G such that the vertices are drawn at grid points and the edges are drawn as nonintersecting straight line segments. In this paper we show that if a 4-connected plane graph G has at least four vertices on its external face, then G can be embedded on a grid of size W × H such that W + H ≤n, W ≤ (n + 3)/2 and H ≤ 2(n - 1)/3, where n is the number of vertices of G. Such an embedding can be computed in linear time.
Production of vector-meson pairs in hadronic collisions

Production in hadronic collisions of 2/sup + +/ Q/sup 2/Q/sup 2/ states which decay predominantly to vector-meson pairs are discussed based on a Drell-Yan-type mechanism with gluon fusion via the color vector-dominance model. The 2/sup + +/ phiphi resonance at 2.16 GeV produced in pp and ..pi..p collisions is interpreted as a 2/sup + +/ sss-bar s-bar four-quark state. The calculated mass and width of this four-quark state, its characteristic S-wave decay, and the theoretical production cross sections in pp reaction at p/sub L/ = 400 GeV/c and ..pi..p reaction at p/sub L/ = 100 GeV/c are consistent with experimental data. Estimates of the hadronic production cross sections and their longitudinal- and transverse-momentum distributions for various channels of vector-meson pairs are also presented.
Hepatitis C and hepatocellular carcinoma

Hepatitis C virus (HCV) infection is now recognized to be a major risk factor for hepatocellular carcinoma (HCC), evidenced by finding both antibody to HCV (anti-HCV) and HCV RNA in serum of a substantial proportion of patients with HCC around the world and by the progression of liver disease to cirrhosis and HCC in individual patients infected with HCV. There seems to be an incubation period of two to three decades on average in most cases of HCV-related HCC. HCV infection usually results in development of HCC via cirrhosis, although the possibility of direct carcinogenic effects of HCV is still under study. Possible additional risk factors include infection with HCV genotype 1b, alcohol consumption, and co-infection with the hepatitis B virus. Estimates of the development of HCC among patients with cirrhosis of all types range between 1% and 4% per year. Assuming that 20% of patients with chronic hepatitis C go on to develop cirrhosis over a 10-year period, between 1.9% and 6.7% of all patients with chronic hepatitis C can be expected to develop HCC over the first two decades of infection. Although tests are available to screen for early HCC, the results of treating these small tumors have been disappointing. Thus, it is imperative that cost-effective means be developed for screening and prevention of HCV-related HCC.
Limitations for Nonlinear Observation Over Erasure Channel

In this technical note, we study the problem of state observation of nonlinear systems over an erasure channel. The notion of mean square exponential stability is used to analyze the stability property of observer error dynamics. The main results of this technical note prove, fundamental limitation arises for mean square exponential stabilization of the observer error dynamics, expressed in terms of probability of erasure, and positive Lyapunov exponents of the system. Positive Lyapunov exponents are a measure of average expansion of nearby trajectories on an attractor set for nonlinear systems. Hence, the dependence of limitation results on the Lyapunov exponents highlights the important role played by nonequilibrium dynamics on the attractor set in observation over an erasure channel. The limitation on observation is also related to measure-theoretic entropy of the system, which is another measure of dynamical complexity. The limitation result for the observation of linear systems is obtained as a special case, where Lyapunov exponents are shown to emerge as the natural generalization of eigenvalues from linear systems to nonlinear systems.
UBVRI Photometric Standard Stars Around the Celestial Equator: Updates and Additions

New broadband UBVRI photoelectric observations on the Johnson-Kron-Cousins photometric system have been made of 202 stars around the sky, and centered at the celestial equator. These stars constitute both an update of and additions to a previously published list of equatorial photometric standard stars. The list is capable of providing, for both celestial hemispheres, an internally consistent homogeneous broadband standard photometric system around the sky. When these new measurements are included with those previously published by Landolt (1992), the entire list of standard stars in this paper encompasses the magnitude range 8.90 < V < 16.30, and the color index range –0.35 < (B – V) < +2.30.
The integral (orbifold) Chow ring of toric Deligne–Mumford stacks

In this paper we study the integral Chow ring of toric Deligne–Mumford stacks. We prove that the integral Chow ring of a semi-projective toric Deligne–Mumford stack is isomorphic to the Stanley–Reisner ring of the associated stacky fan. The integral orbifold Chow ring is also computed. Our results are illustrated with several examples.
Optimal annual contributions to flexible spending accounts: a rule-of-thumb

Abstract Many employees under-contribute to so-called flexible spending accounts. To maximize expected income after tax and medical spending, contribute to your flexible spending account (FSA) until the probability of spending the last dollar equals one minus your marginal tax rate.
Comment on On a class of exact solutions of the equations of motion of a second grade fluid by C. Fetecău and J. Zierep (Acta Mech. 150, 135-138, 2001)

In a 2001 article, Fetecau and Zierep [1] considered Stokes' first problem for a second grade (SG) fluid, unaware that it had already been solved (correctly) by Puri [2] in 1984. These authors used the Fourier sine transform to obtain, what they believed to be, the exact solution of the resulting initial-boundary-value problem (IBVP). Unfortunately, due to their incorrect computation of the distributional derivative of the Heaviside function, an omission of a critical term in the subsidiary equation occurred, an elementary mistake (gracefully explained in [3]) apparently not uncommon in the literature. Therefore, the solution given in [1] is, generally speaking, incorrect.
An Unconventional Method for Purifying the N-carboxyanhydride Derivatives of γ-alkyl-L-glutamates

Abstract Common impurities in the phosgenation of α -amino acids to produce their N-carboxyanhydride (NCA) derivatives include hydrogen chloride and the hydrochloride salt of the starting amino acid. These impurities can be effectively removed by washing the reaction mixture with water and aqueous bicarbonate at 0 °C prior to isolation of the NCA., despite the well known sensitivity of the NCA to water The method should be particularly useful for NCA derivatives which are isolated as oils since purifying them by recrystallization or solvent washes is not feasible. This study involved specifically the purification of NCA derivatives from a variety of γ-alkyl-L-glutamates and γ-benzyl-L-glutamate.
Synergy, Managerialism or Hubris? An Empirical Examination of Motives for Foreign Acquisitions of U.S. Firms

This study examines the motives underlying foreign acquisitions of U.S. firms, estimates the extent of value creation associated with such acquisitions, and examines how total gains are shared between acquiring firms and targets. We show that the synergy hypothesis is the predominant explanation for our sample of foreign acquisitions of U.S. firms. However, the hubris hypothesis coexists with the synergy hypothesis in explaining the acquisitions in our sample that are characterized by positive total gains. The evidence is also consistent with the managerialism hypothesis for the acquisitions in our sample with negative total gains. We show that the incidence of competition is associated with higher total gains, as well as higher gains to targets.
The gradient effect of transitional magnitude: A source of the vowel context effect

Previous studies have shown that vocalic transitions play an important role in the identification of the consonantal places (e.g., Whalen 1981/1991, Nowak 2006, Babel & McGuire 2013). While it has been intermittantly reported that the contribution of transitions may depend on vowel contexts, the common methodology, i.e., C-V cross-splicing, is too coarse to precisely identify the nature of this effect. In the present study, vocalic transitions are systematically manipulated and used as a gradient variable by incrementally removing the transitional period of the three vowels /u a e/ following alveolopalatal sibilant /ɕ/ in Polish. In an identification task, native Polish speakers were given a choice between /ɕ/ and /ʂ/ for stimuli with varying levels of palatal transitions. The results showed that participants’ perception is gradient: greater transitions overall elicit more palatal responses in all vowel contexts. More importantly, it has been shown that the apparent vowel effect can be largely reduced to ...
Comparison of respiratory and cardiovascular effects of isoproterenol, propranolol, and practolol in asthmatic and normal subjects

Pulmonary functions, by means of FEV1, FVC, and airway resistance, and cardiovascular responses, i.e., ECG, blood pressure, and pulse contour, were measured in 10 control and 15 symptom-free asthmatic subjects during and after the infusions of isoproterenol, with or without previous administration of propranolol or practolol. Bronchial sensitivity to methacholine and response to isoproterenol after methacholine were also measured. Bronchial sensitivity to methacholine challenge was markedly enhanced by propranolol and the effect of isoproterenol infusion on the pulmonary function was also significantly diminished, whereas practolol did not reveal any effect on bronchial sensitivity to methacholine or isoproterenol. The above changes were much more profound in symptom-free asthmatic subjects than in control subjects. The results suggest that practolol does not significantly affect the beta-2 bronchial receptors, is safe to use in asthmatic subjects, and is consistent with an abnormality of these receptors in bronchial asthma.
Effects of phase-change energy storage on the performance of air-based and liquid-based solar heating systems

Abstract Models describing the transient behavior of phase-change energy storage (PCES) units are presented. Simulation techniques are used in conjunction with these models to determine the performance of solar heating systems utilizing PCES. Both air-based and liquid-based systems are investigated. The effects of storage capacity, storage unit heat transfer characteristics, collector area and location on the system performance are investigated for systems utilizing sodium sulfate decahydrate and paraffin wax as storage media. Optimum ranges of storage sizes are recommended on the basis of systems' thermal performance. Comparison is made between systems utilizing PCES and those using sensible heat storage, viz. rock beds in air-based systems and water tanks in liquid-based systems. The variation of the solar supplied fraction of load with storage size and collector area is given for systems utilizing both types of storage. The effects of location and collector energy loss coefficient on the relative performance of PCES and sensible heat storage are also investigated.
Multiple D0-branes in Weakly Curved Backgrounds

Abstract We investigate further our recent proposal for the form of the matrix theory action in weak background fields. Using Seiberg's scaling argument we relate the matrix theory action to a low-energy system of many D0-branes in an arbitrary but weak NS-NS and R-R background. The resulting multiple D0-brane action agrees with the known Born-Infeld action in the case of a single brane and gives an explicit formulation of many additional terms which appear in the multiple brane action. The linear coupling to an arbitrary background metric satisfies the non-trivial consistency condition suggested by Douglas that the masses of off-diagonal fields are given by the geodesic distance between the corresponding pair of D0-branes. This agreement arises from combinatorial factors which depend upon the symmetrized trace ordering prescription found earlier for higher moments of the matrix theory stress-energy tensor. We study the effect of a weak background metric on two graviton interactions and find that our formalism agrees with the results expected from supergravity. The results presented here can be T-dualized to give explicit formulae for the operators in any D-brane world-volume theory which couple linearly to bulk gravitational fields and their derivatives.
Characteristics of the initial rising portion of near and far lightning return stroke electric field waveforms

Abstract We examine initial rising portions of electric field waveforms of negative first return strokes in natural cloud-to-ground lightning recorded simultaneously at near and far distances from the lightning channel. The near and far field-measuring stations are located at Camp Blanding and in Gainesville, Florida, respectively, separated by a distance of about 45 km. A total of five return strokes had been recorded in 2007–2008, four of which were analyzed in detail (one was not suitable for analysis due to saturation of electric field waveform at the far station). Field waveform characteristics, including overall zero-to-peak and 10-to-90% risetimes, duration of slow front, fast transition 10-to-90% risetime, and magnitude of slow front relative to the peak, were found to be similar to those reported from other studies, in which the field propagation path was over ground (as opposed to sea water). It is shown, via modeling, that the slow front in electric field waveforms at far distances is primarily due to the radiation field component, while at near distances it is composed of comparable contributions from all three components of electric field. For both measured and model-predicted waveforms, the durations of the slow front appear to be similar at near and far distances from the lightning channel.
Variable density linear acoustic inverse problem.

Abstract The linear acoustic inverse problem is solved simultaneously for density (ρ) and compressibility (κ) using the basic ideas of diffraction tomography (DT). The key to solving this problem is to utilize frequency diversity to obtain the required independent measurements. The receivers are assumed to be in the far field of the object, and plane wave incidence is also assumed. The Born approximation is used to arrive at a relationship between the measured pressure field and two terms related to the spatial Fourier transform of the two unknowns, ρ and κ. The term involving compressibility corresponds to monopole scattering and that for density to dipole scattering. Measurements at several frequencies are used and a least squares problem is solved to reconstruct ρ and κ at the same time. It is observed that the low spatial frequencies in the spectra of ρ and κ produce inaccuracies in the results. Hence, a regularization method is devised to remove this problem. Several results are shown. Low contrast objects for which the above analysis holds are used to show that good reconstructions are obtained for both density and compressibility after regularization is applied.
Heavy Meson Production at a Low-Energy Photon Collider

A low-energy γγ collider has been discussed in the context of a testbed for a γγ interaction region at the Next Linear Collider (NLC). We consider the production of heavy mesons at such a testbed using Compton-backscattered photons and demonstrate that their production rivals or exceeds those by BELLE, BABAR or LEP where they are produced indirectly via virtual γγ luminosities.
Blading Response to Potential Field Interactions in Axial- and Radial-Flow Turbomachinery

An unsteady aerodynamic model is developed to predict the response of both axial- and radial-e ow turbomachinery blading resulting from potential e eld interactions. For axial-e ow turbomachines this is accomplished by extending a compressible e at-plate cascade analysis to account for the induced velocities due to an adjacent blade row’ s potential e eld. The blading response in a radial cascade consisting of logarithmic spiral airfoils is then calculated utilizing a conformal transformation mapping of the radial geometry to an equivalent axial cascade, enabling existing axial cascade models to be used for radiale ow turbomachine blade rows. This model is then used to demonstrate the forced response characteristics of a blade row to potential e elds of both upstream and downstream airfoil rows and to upstream bladerow-generated vortical wakes, including the differences between the response of axial- and radial-e ow turbomachinery blading. For both the axial- and radial-e ow blade rows, the nondimensional unsteady aerodynamic response amplitudes generated by airfoil row potential and vortical wake-forcing functions were of the same order of magnitude. Thus, for closely spaced, highly loaded blade rows, both wake and potential e eld interactions may be of equal signie cance.
EXCITON SPIN STATES IN NANOCRYSTAL QUANTUM DOTS REVEALED BY SPIN-POLARIZED RESONANT PHOTOLUMINESCENCE AND RAMAN SPECTROSCOPY

We performed spin-polarized resonant Raman and resonant photoluminescence excitation spectroscopy (also known as "fluorescence line narrowing") on ZnS-capped CdSe nanocrystal quantum dots in high magnetic fields to 33 Tesla and temperatures down to 1.7K, which allows detailed investigation of the excitonic spin states. In these experiments, spin-polarized electrons and holes are resonantly injected by circularly polarized light into colloidal quantum dots of specific size, using a narrowband tunable dye laser and a fiber-coupled probe that is specially-designed for use in high-field magnets. In addition to the expected broad features associated with excitonic recombination and Raman-like peaks associated with quantized acoustic phonons, the photoluminescence spectra measured at magnetic fields larger than 10 Tesla develop a sharp peak, which moves roughly linearly with applied magnetic field. Further, the energy of this high-field peak varies systematically as a function of nanocrystal size. However, unli...
Heat Transfer Across Metal-Dielectric Interfaces During Ultrafast-Laser Heating

Heat transfer across a metal-dielectric interface involves coupled transport of electrons and phonons in metal and phonons in dielectric, which can be accomplished by coupling between phonons in metal and dielectric or direct coupling between electrons in metal and phonons in dielectric. Direct electron-phonon coupling across the metal-dielectric interface is neglected in some studies [1, 2] but considered in some others [3–5]. We investigate heat transfer across metal-dielectric interfaces during ultrafast-laser heating by employing transient thermo-reflectance (TTR) measurements on Au-Si samples. With ultrafast-laser heating that creates strong thermal non-equilibrium between electrons and phonons in metal, it is possible to isolate the effect of direct electron-phonon coupling across the interface. Simulation results based on the two-temperature model (TTM) are compared with the measurement results. The comparison shows a strong direct coupling between electrons in metal and phonons in dielectric.Copyright © 2011 by ASME
Intermolecular reaction of nitroxide radicals with biradical intermediates generated from aromatic enediynes

Abstract 1,4-Dehydronaphthalene biradicals generated by thermolysis of aromatic enediynes can be trapped with the nitroxide radical TEMPO. The isolated products, however, are not the direct trapping products but 1,4-naphthoquinones resulting from the homolysis of NO bonds of trapping products.
Policy Formulation: Where Ignorant Armies Clash by Night

This article argues that many of the shortcomings generally ascribed to policy analysis can be attributed to the intractable nature of the problems being addressed. That is, public policy issues are inherently difficult, resistant to resolution and fully loaded with significant costs. Those costs can easily render a potential policy solution helpless or perhaps even counterproductive, despite the best-conceived and best-intended plans of its proponents. A policy design perspective can help identify some of the downstream dilemmas and possible help alleviate them. However, like most policy approaches, policy design must be used with careful circumspection, else its pitfalls overwhelm its promises.
Preliminary Evaluation of RCA C83036E Prototype Photomultiplier

Characteristics of the prototype RCA C83036E 52 mm diameter photomultiplier have been measured. The results of the measurements of the gain, dark current, photocathode quantum efficiency, peak output current, electron transit time, and output pulse rise time as a function of voltage between anode and cathode are given. Furthermore, single photoelectron time spread, multiphotoelectron time resolution, pulse-height spectrum and afterpulse time spectrum were measured and are discussed.
Hadronic contributions to the muon lifetime

Abstract Hadronic corrections to the muon lifetime are calculated in the Fermi theory in the presence of QED using dispersion relations. The result, after convolution of hadron data with the calculated perturbative kernel is ΔΓ had =−Γ 0 α π 2 0.042 where Γ 0 is the tree-level width. The results are also used to obtain the corrections to the muon lifetime coming from virtual muon and tau loops ΔΓ muon =Γ 0 α π 2 16987 576 − 85 36 ζ(2)− 64 3 ζ(3) =−Γ 0 α π 2 0.0364333 , ΔΓ tau =−Γ 0 α π 2 0.00058.
Numerical methods for mixed boundary value problems of shells of revolution

Abstract For the solution of a mixed boundary value problem of an axisymmetric shell, for which different variables are prescribed over portions of the circular boundaries, methods arc required which are applicable to boundary value problems governed by two-dimensional partial differential equations. Two such methods are discussed in this paper. One uses a truncated series expansion in terms of separable solutions, and the other employs finite difference expressions in the circumferential direction. Using these two techniques, the problem is brought to a one-dimensional form, and then solved with the multisegment method of direct numerical integration. An example of pure bending of a cylindrical shell with a semicircular slit is solved by both methods, and numerical results are given.
Crystallographic and Biochemical Analysis of the Ran-binding Zinc Finger Domain.

The nuclear pore complex (NPC) resides in circular openings within the nuclear envelope and serves as the sole conduit to facilitate nucleocytoplasmic transport in eukaryotes. The asymmetric distribution of the small G protein Ran across the nuclear envelope regulates directionality of protein transport. Ran interacts with the NPC of metazoa via two asymmetrically localized components, Nup153 at the nuclear face and Nup358 at the cytoplasmic face. Both nucleoporins contain a stretch of distinct, Ran-binding zinc finger domains. Here, we present six crystal structures of Nup153-zinc fingers in complex with Ran and a 1.48 A crystal structure of RanGDP. Crystal engineering allowed us to obtain well diffracting crystals so that all ZnF-Ran complex structures are refined to high resolution. Each of the four zinc finger modules of Nup153 binds one Ran molecule in apparently non-allosteric fashion. The affinity is measurably higher for RanGDP than for RanGTP and varies modestly between the individual zinc fingers. By microcalorimetric and mutational analysis, we determined that one specific hydrogen bond accounts for most of the differences in the binding affinity of individual zinc fingers. Genomic analysis reveals that only in animals do NPCs contain Ran-binding zinc fingers. We speculate that these organisms evolved a mechanism to maintain a high local concentration of Ran at the vicinity of the NPC, using this zinc finger domain as a sink.
Effects of buffer layer thickness and doping concentration on SiC MESFET characteristics

Two-dimensional simulations have been carried out using the Atlas/spl reg/ device simulator to investigate the effects of the buffer layer thickness and doping concentration on the electrical characteristics of the SiC MESFET. The variations of transconductance, output resistance, gate-source capacitance, gate-drain capacitance and (cutoff frequency) f/sub T/ with respect to the change in buffer layer thickness and doping concentration have been investigated. It is observed that the performances of MESFET can be improved by reducing the leakage of channel carrier into the substrate at high drain bias, which is achieved by increasing buffer layer doping density and/or increasing buffer layer thickness. For a SiC MESFET with buffer layer thickness of 0.3/spl mu/m and gate length of 1/spl mu/m, drain current increases from 0.1 A//spl mu/m to above 0.45A//spl mu/m as the buffer layer doping density is decreased from 1.9/spl times/10/sup 17/ cm/sup -3/ to 1/spl times/10/sup 16/ cm/sup -3/. The simulations were carried out at a gate-source voltage of -1V and a drain-source voltage of 15V. Under similar conditions, the output resistance decreases from 1.2/spl times/10/sup 6/ /spl Omega///spl mu/m to 1.0/spl times/10/sup 5/ /spl Omega///spl mu/m, and the transconductance decreases from 5.9mS//spl mu/m to 5.3mS//spl mu/m, and f/sub T/ decreases from 11GHz to 8GHz.
Testing radiative neutrino mass generation via R-parity violation at the Tevatron

Abstract An R-parity violating SUSY model with lepton-number violating couplings λ ′ i 33 , i =2,3, can generate a neutrino mass spectrum that explains the recent results from neutrino oscillation experiments. These R-parity violating couplings lead to a clean signal with at least one isolated lepton and at least three tagged b jets that is accessible in chargino and neutralino production at the Tevatron collider. This signature can be probed at 3 σ up to m 1/2 =230 GeV (320 GeV) with an integrated luminosity of 2 fb −1 (30 fb −1 ).
Is the Universe a Vacuum Fluctuation

The author proposes a big bang model in which our Universe is a fluctuation of the vacuum, in the sense of quantum field theory. The model predicts a Universe which is homogeneous, isotropic and closed, and consists equally of matter and anti-matter. All these predictions are supported by, or consistent with, present observations.
Physically-Based Global Downscaling: Climate Change Projections for a Full Century

A global atmosphere/land model with an embedded subgrid orography scheme is used to simulate the period 1977-2100 using ocean surface conditions and radiative constituent concentrations for a climate change scenario. Climate variables simulated for multiple elevation classes are mapping according to the high-resolution of topography in ten regions with complex terrain. Analysis of changes in the simulated climate lead to the following conclusions. Changes in precipitation vary widely, with precipitation increasing more with increasing altitude in some region, decreasing more with altitude in others, and changing little in still others. In some regions the sign of the precipitation change depends on surface elevation. Changes in surface air temperature are rather uniform, with at most a two-fold difference between the largest and smallest changes within a region. In most cases the warming increases with altitude. Changes in snow water are highly dependent on altitude. Absolute changes usually increase with altitude, while relative changes decrease. In places where snow accumulates, an artificial upper bound on snow water limits the sensitivity of snow water to climate change considerably. The simulated impact of climate change on regional mean snow water varies widely, with little impact in regions in which the upper bound on snowmore » water is the dominant snow water sink, moderate impact in regions with a mixture of seasonal and permanent snow, and profound impacts on regions with little permanent snow.« less
Visual evoked potentials for attentional gating in a brain-computer interface

For synchronous brain-computer interface (BCI) paradigms tasks that utilize visual cues to direct the user, the neural signals extracted by the computer are representative of voluntary modulation as well as evoked responses. For these paradigms, the evoked potential is often overlooked as a source of artifact. In this paper, we put forth the hypothesis that cue priming, as a mechanism for attentional gating, is predictive of motor imagery performance, and thus a viable option for self-paced (asynchronous) BCI applications. We approximate attention by the amplitude features of visually evoked potentials (VEP)s found using two methods: trial matching to an average VEP template, and component matching to a VEP template defined using independent component analysis (ICA). Templates were used to rank trials that display high vs. low levels of fixation. Our results show that subject fixation, measured by VEP response, fails as a predictor of successful motor-imagery task completion. The implications for the BCI community and the possibilities for alternative cueing methods are given in the conclusions.
Uniform bounds and symbolic powers on smooth varieties

The purpose of this note is to show how one can use multiplier ideals toestablish effective uniform bounds on the multiplicative behavior of certainfamilies of ideal sheaves on a smooth algebraic variety. In particular, weprove a quick but rather surprising result concerning the symbolic powersof radical ideals on such a variety.Let
MAPS, PDE'S AND SOLITARY WAVES

We describe a map-based model which reproduces many of the behaviors seen in partial differential equations (PDE's). Like PDE's, we show that this model can support an infinite number of stationary solutions, traveling solutions, breathing solutions, and elastically colliding solutions. Unlike PDE's, the model can be applied with minimal computational machinery, and few sources of numerical error. Moreover, this model clarifies possible mechanisms by which various coherent solutions are maintained in the face of diffusion.
Social media assimilation in firms: Investigating the roles of absorptive capacity and institutional pressures

Firms are increasingly employing social media to manage relationships with partner organizations, yet the role of institutional pressures in social media assimilation has not been studied. We investigate social media assimilation in firms using a model that combines the two theoretical streams of IT adoption: organizational innovation and institutional theory. The study uses a composite view of absorptive capacity that includes both previous experience with similar technology and the general ability to learn and exploit new technologies. We find that institutional pressures are an important antecedent to absorptive capacity, an important measure of organizational learning capability. The paper augments theory in finding the role and limits of institutional pressures. Institutional pressures are found to have no direct effect on social media assimilation but to impact absorptive capacity, which mediates its influence on assimilation.
State Trajectories Used to Observe and Control DC-to-DC Converters

State-plane analysis techniques are employed to study the voltage stepup energy-storage dc-to-dc converter. Within this framework, an example converter operating under the influence of a constant on-time and a constant frequency controller is examined. Qualitative insight gained through this approach is used to develop a conceptual free-running control law for the voltage stepup converter which can achieve steady-state operation in one on/off cycle of control. Digital computer simulation data are presented to illustrate and verify the theoretical discussions presented.
Originations:Land and sea compared

Abstract The dynamics of origination in the fossil record of three marine groups (molluscs, echinoderms andfishes) and three terrestrial groups (mammals, insects and plants) is analyzed in this paper. Four hypotheses are tested: (1) secular decline in lineage origination; (2) secular decline in evolutionary innovation; (3) diversity dependence of lineage origination; (4) self-organized criticality of lineage origination. A decline in lineage origination and in the production of major innovations is present in all groups, suggesting controls that transcend the land-sea distinction. The relationship between diversity and origination appears to be strong in the sea and weak on land, a difference that might imply environment-specific controls. Mixed support for a logistic dynamics of origination is found. Finally, no general support for a self-organized critical behaviour of origination is found, with the predictions appearing to hold only in insects and pteridophytes/gymnosperms.
Dynamics of Rotating Accretion Flows Irradiated by a Quasar

We study the axisymmetric, time-dependent hydrodynamics of rotating flows that are under the influence of supermassive black hole gravity and radiation from an accretion disk surrounding the black hole (BH). This work is an extension of the earlier work presented by Proga, in which nonrotating flows were studied. Here, we consider effects of rotation, a position-dependent radiation temperature, density at large radii, and uniform X-ray background radiation. As in the nonrotating case, the rotating flow settles into a configuration with two components, (1) an equatorial inflow and (2) a bipolar inflow/outflow with the outflow leaving the system along the pole. However, with rotation the flow does not always reach a steady state. In addition, rotation reduces the outflow collimation and the outward flux of mass and kinetic energy. Moreover, rotation increases the outward flux of the thermal energy and can lead to fragmentation and time variability of the outflow. We also show that a position-dependent radiation temperature can significantly change the flow solution. In particular, the inflow in the equatorial region can be replaced by a thermally driven outflow. Generally, as has been discussed and shown in the past, we find that self-consistently determined preheating/cooling from the quasar radiation can significantly reduce the rate at which the central BH is fed with matter. However, our results also emphasize a little-appreciated feature. Namely, quasar radiation drives a nonspherical, multitemperature, and very dynamic flow. These effects become dominant for luminosities in excess of 0.01 of the Eddington luminosity.
A BINARY ORBIT FOR THE MASSIVE, EVOLVED STAR HDE 326823, A WR+O SYSTEM PROGENITOR

The hot star HDE 326823 is a candidate transition-phase object that is evolving into a nitrogen-enriched Wolf-Rayet star. It is also a known low-amplitude, photometric variable with a 6.123 day period. We present new, high- and moderate-resolution spectroscopy of HDE 326823, and we show that the absorption lines show coherent Doppler shifts with this period while the emission lines display little or no velocity variation. We interpret the absorption line shifts as the orbital motion of the apparently brighter star in a close, interacting binary. We argue that this star is losing mass to a mass gainer star hidden in a thick accretion torus and to a circumbinary disk that is the source of the emission lines. HDE 326823 probably belongs to a class of objects that produce short-period WR+O binaries.
On the online bin packing problem

A new framework for analyzing online bin packing algorithms is presented. This framework presents a unified way of explaining the performance of algorithms based on the Harmonic approach. Within this framework, it is shown that a new algorithm, Harmonic++, has asymptotic performance ratio at most 1.58889. It is also shown that the analysis of Harmonic+1 presented in Richey [1991] is incorrect; this is a fundamental logical flaw, not an error in calculation or an omitted case. The asymptotic performance ratio of Harmonic+1 is at least 1.59217. Thus, Harmonic++ provides the best upper bound for the online bin packing problem to date.
Conjectured Metastable Super-explosives Formed Under High Pressure for Thermonuclear Ignition

If matter is suddenly put under a high pressure, for example, a pressure of 100 Mb = 1014 dyn/cm2, it can undergo a transformation into molecular excited states, bound by inner electron shells, with keV potential wells for the electrons. If this happens, the electrons can under the emission of X-rays go into the groundstate of the molecule formed under the high pressure. At a pressure of the order ∼1014 dyn/cm2, these molecules store in their excited states an energy with an energy density of the order ∼1014 erg/cm3, about 1,000 times larger than for combustible chemicals under normal pressures. Furthermore, with the much larger optical path length of keV photons compared to the path length of eV photons, these superexplosives can reach at their surface an energy flux density (c = 3 × 1010 cm/s) of the order (c/3) × 1014 = 1024 erg/cm2s = 1017W/cm2, large enough for the ignition of thermonuclear reactions.
A simple method for the conversion of carboxylic acids into thioacids with Lawesson's reagent

A one-step protocol for the conversion of carboxylic acids to thioesters, using Lawesson’s Reagent, has been developed.
Role of acentric displacements on the crystal structure and second-harmonic generating properties of RbPbCO3F and CsPbCO3F

Two lead fluorocarbonates, RbPbCO3F and CsPbCO3F, were synthesized and characterized. The materials were synthesized through solvothermal and conventional solid-state techniques. RbPbCO3F and CsPbCO3F were structurally characterized by single-crystal X-ray diffraction and exhibit three-dimensional (3D) crystal structures consisting of corner-shared PbO6F2 polyhedra. For RbPbCO3F, infrared and ultraviolet–visible spectroscopy and thermogravimetric and differential thermal analysis measurements were performed. RbPbCO3F is a new noncentrosymmetric material and crystallizes in the achiral and nonpolar space group P6m2 (crystal class 6m2). Powder second-harmonic generation (SHG) measurements on RbPbCO3F and CsPbCO3F using 1064 nm radiation revealed an SHG efficiency of approximately 250 and 300 × α-SiO2, respectively. Charge constants d33 of approximately 72 and 94 pm/V were obtained for RbPbCO3F and CsPbCO3F, respectively, through converse piezoelectric measurements. Electronic structure calculations indica...
The effect of cigarette prices on youth smoking.

Prior economic research provides mixed evidence on the impact of cigarette prices on youth smoking. This paper empirically tests the effects of various price measures on youth demand for cigarettes using data collected in a recent nationally representative survey of 17 287 high school students. In addition to commonly used cigarette price measures, the study also examined the effect of price as perceived by the students. This unique information permits the study of the effect of teen-specific price on cigarette demand. The analysis employed a two-part model of cigarette demand based on a model developed by Cragg (1971) in which the propensity to smoke and the intensity of the smoking habit are modeled separately. The results confirm that higher cigarette prices, irrespective of the way they are measured, reduce probability of youth cigarette smoking. There is also some evidence of negative price effect on smoking intensity, but it is sensitive to the price measure used in the model. The largest impact on cigarette demand has the teen-specific, perceived price of cigarettes.
Cooperative Visualization of Computational Fluid Dynamics

Tempus Fugit/Interview is a computational fluid dynamics visualization application for which processing is distributed between high performance graphics workstations and supercomputers. Facilities are provided in the application for more than one user to view shared images creating a cooperative visualization environment. The way in which the computation is partitioned between the super computer and the workstations is critical to the capability of the application to present simultaneous, identical, animated images of fluid dynamics to more than one user.
A decentralized control policy for adaptive information gathering in hazardous environments

This paper proposes an algorithm for driving a group of resource-constrained robots with noisy sensors to localize an unknown number of targets in an environment, while avoiding hazards at unknown positions that cause the robots to fail. The algorithm is based upon the analytic gradient of mutual information of the target locations and measurements and offers two primary improvements over previous algorithms [6], [13]. Firstly, it is decentralized. This follows from an approximation to mutual information based upon the fact that the robots' sensors and environmental hazards have a finite area of influence. Secondly, it allows targets to be localized arbitrarily precisely with limited computational resources. This is done using an adaptive cellular decomposition of the environment, so that only areas that likely contain a target are given finer resolution. The estimation is built upon finite set statistics, which provides a rigorous, probabilistic framework for multi-target tracking. The algorithm is shown to perform favorably compared to existing approximation methods in simulation.
A Search for ortho-benzyne (o-C6H4) in CRL 618

Polycyclic aromatic hydrocarbons (PAHs) have been proposed as potential carriers of the unidentified infrared bands (UIRs) and the diffuse interstellar bands (DIBs). PAHs are not likely to form by gas-phase or solid-state interstellar chemistry, but rather might be produced in the outflows of carbon-rich evolved stars. PAHs could form from acetylene addition to the phenyl radical (C6H5), which is closely chemically related to benzene (C6H6) and ortho-benzyne (o-C6H4). To date, circumstellar chemical models have been limited to only a partial treatment of benzene-related chemistry, and so the expected abundances of these species are uncertain. A detection of benzene has been reported in the envelope of the proto-planetary nebula (PPN) CRL 618, but no other benzene-related species has been detected in this or any other source. The spectrum of o-C6H4 is significantly simpler and stronger than that of C6H5, and so we conducted deep Ku-, K-, and Q-band searches for o-C6H4 with the Green Bank Telescope. No transitions were detected, but an upper limit on the column density of 8.4 × 1013 cm−2 has been determined. This limit can be used to constrain chemical models of PPNe, and this study illustrates the need for complete revision of these models to include the full set of benzene-related chemistry.
Glass transition behavior of polymer films of nanoscopic dimensions

Glass transition behavior of nanoscopically thin polymer films is investigated by means of molecular dynamics simulations. We study thin polymer films composed of bead-spring model chains and supported on an idealized fcc lattice substrate surface. The impact on the glass transition temperature of the strength of polymer-surface interaction and of chain grafting to the surface is investigated. Three different methods-volumetric, energetic, and dynamic-are used to determine the glass transition temperature of the films. On the basis of these, we are able to identify two different transition temperatures. When the temperature is lowered, a first transition occurs that is characterized by an anomaly in the heat capacity. Upon decreasing the temperature further, a point is reached at which the internal relaxation times diverge, as calculated, using for instance, the mode coupling theory. In qualitative agreement with the experiments, the former temperature depends on the characteristics of the polymer-surface interaction. By contrast, the latter temperature is independent of these.
Standard electrode potentials of the elements as a fundamental periodic property of atomic number

Abstract It is shown that the standard electrode potentials of the elements are a periodic property of the atomic number. The experimentally measured standard electrode potential of an element is related to fundamental elemental properties through a thermodynamic cycle. Metal atoms are first atomized to the vapor phase, are then ionized to form gaseous ions, and are then hydrated to form an ion–water cluster, which is next introduced into the aqueous solution. The standard electrode potential calculated from such a cycle is in good agreement with standard values for univalent, divalent and trivalent metal ions. It is shown that the periodicity in the standard electrode potential as a function of atomic number arises from the periodicity in the enthalpy term which is used to calculate standard electrode potentials from the equivalent thermodynamic cycle.
Data analysis and statistics: an expository overview

Data analysis is not a new subject. It has accompanied productive experimentation and observation for hundreds of years. At times, as in the work of Kepler, it has produced dramatic results.
Two-Phase Synthesis of (−)-Taxuyunnanine D

The first successful effort to replicate the beginning of the Taxol oxidase phase in the laboratory is reported, culminating in the total synthesis of taxuyunnanine D, itself a natural product. Through a combination of computational modeling, reagent screening, and oxidation sequence analysis, the first three of eight C–H oxidations (at the allylic sites corresponding to C-5, C-10, and C-13) required to reach Taxol from taxadiene were accomplished. This work lays a foundation for an eventual total synthesis of Taxol capable of delivering not only the natural product but also analogs inaccessible via bioengineering.
A Discrete Leading Symbol and Spectral Asymptotics for Natural Differential Operators

We initiate a systematic study of natural differential operators in Riemannian geometry whose leading symbols are not of Laplace type. In particular, we define a discrete leading symbol for such operators which may be computed pointwise, or from spectral asymptotics. We indicate how this can be applied to the computation of another kind of spectral asymptotics, namely asymptotic expansions of fundamental solutions, and to the computation of conformally covariant operators.