cssi/SciSciGPT-SciSciNet huggingface dataset:
Resident participation in laparoscopic hysterectomy: impact of trainee involvement on operative times and surgical outcomes

OBJECTIVE: The purpose of this study was to determine the impact of resident involvement on morbidity after total laparoscopic hysterectomy for benign disease. STUDY DESIGN: We performed a retrospective review of a National Surgical Quality Improvement Program database of total laparoscopic hysterectomy for benign disease that was performed with resident involvement vs attending alone between Jan. 1, 2008, and Dec. 31, 2011. Surgical operative times and morbidity and mortality rates were compared.Binary logistic regression wasusedtocontrolforcovariates that were significant on univariate analysis (P < .05). RESULTS:Atotalof3441patientswereidentifiedashavingundergone a total laparoscopic hysterectomy for benign disease. The mean age of patients was 47.4 � 11.1 years; the mean body mass index was 30.6 � 7.9 kg/m 2 . A resident participated in 1591 of cases (46.2%); 1850 of the procedures (53.8%) were done by an attending physician alone. Cases with resident involvement had higher mean age, Charlson morbidity scoring, and American Society of Anesthesiologists classification and were more likely to be inpatient cases. With resident involvement, the mean operative time was increased (179.29 vs 135.46 minutes; P < .0001). There were no differences in the rates of experiencing at least 1 complication (6.8% for resident involvement vs 5.4% for attending alone; P ¼ .5), composite severe morbidity (1.3% residentvs1.0%attendingalone),or30-daymortalityrate(0%resident vs 0.1% attending alone). Additionally, there were no differences between groups in the infectious, wound, neurorenal, thromboembolic, septic, and cardiopulmonary complications. Cases with resident involvement had significantly increased rates of postoperative transfusion of packed red blood cells (2% vs 0.4%; P < .0001), reoperation (2.2% vs 1.3%; P ¼ .048), and a 30-day readmission (5.5% vs 2.9%; P ¼ .015). In models that were adjusted for factors that differed between the 2 groups, cases with resident involvement had increased oddsofreceivingpostoperativebloodtransfusion(oddsratio[OR],4.98; 95% confidence interval [CI], 2.18e11.33),reoperation (OR,1.7,95% CI, 1.01e2.89) and readmission (OR, 1.93, 95% CI, 1.09e3.42). CONCLUSION: Resident involvement in total laparoscopic hysterectomy for benign disease was associated with clinically appreciable longer surgical time and small differences in the rates of postoperative transfusions, reoperation, and readmission. However, the rates of overall complications, severe complications, and 30-day mortality rate remain comparable.
Does the Crab Have a Shell

Abstract : We present deep images of a region around the Crab Nebula made with the VLA, utilizing new imaging and deconvolution algorithms in a search for a faint radio shell. The existence of a high-velocity, hydrogen-rich envelope has been predicted to account for the low total mass and kinetic energy of the observed nebula. No radio emission was detected from an extended source outside the Crab Nebula. Our limits on surface brightness are sufficiently low to rule out the existence of a shell around the Crab whose brightness is at least 2 orders of magnitude below that of SN 1006, the faintest historical shell-type supernova remnant. We consider models for the progenitor star and the presupernova environment and conclude that if a fast, outer shock exists, then it has a sharply reduced efficiency at accelerating relativistic particles from the kinetic energy of the blast wave. We also looked for a steepening of the spectral index along the boundary of the Crab Nebula itself, the signature of an outer shock. However, contrary to previous claims, no such steepening was found. The absence of any evidence at radio wavelengths that either the Crab Nebula or a hypothetical shell is interacting with the ambient medium leads to an interpretation that the supernova of A.D. 1054 was a peculiar low-energy event.
The Socialization of Undergraduate Accounting Students

One purpose of accounting education is to introduce students to the values and ethical standards of the accounting profession (AAA Bedford Committee Report 1986). This study investigates whether undergraduate accounting education is successful at instilling in accounting students a sense of responsibility to financial statement users. In a longitudinal study of accounting and other business students, we find that accounting students oppose earnings management more strongly during their senior year than they did during their sophomore year. We also find that senior accounting students oppose earnings management more strongly than do senior students in other business disciplines. These results are consistent with a socialization process taking place wherein accounting students learn to give priority to financial statement users' needs, while students majoring in other business disciplines come to identify more closely with the goals of corporate managers.
Nuclear Disks of Gas and Dust in Early-Type Galaxies and the Hunt for Massive Black Holes: Hubble Space Telescope Observations of NGC 6251

We discuss Hubble Space Telescope (HST) optical images and spectra of NGC 6251, a giant E2 galaxy and powerful radio source at a distance of 106 Mpc (for H0=70 km s-1 Mpc-1). The galaxy is known to host a very well-defined dust disk; the exceptional resolution of our V and I images allows a detailed study of the disk structure. Furthermore, narrowband images centered on the Hα + [N II] emission lines reveal the presence of ionized gas in the inner 03 of the disk. We used the HST Faint Object Spectrograph with the 009 aperture to study the velocity structure of the disk. Dynamical models were constructed for two extreme (in terms of central concentration) analytical representations of the stellar surface brightness profile, from which the mass density and corresponding rotational velocity are derived assuming a constant mass-to-light ratio (M/L)V~8.5 M☉/L☉. For both representations of the stellar component, the models show that the gas is in Keplerian motion around a central mass ~4-8×108 M☉ and that the contribution of radial flows to the velocity field is negligible.
Learning the language of time: Children's acquisition of duration words.

Abstract Children use time words like minute and hour early in development, but take years to acquire their precise meanings. Here we investigate whether children assign meaning to these early usages, and if so, how. To do this, we test their interpretation of seven time words: second, minute, hour, day, week, month, and year. We find that preschoolers infer the orderings of time words (e.g., hour > minute), but have little to no knowledge of the absolute durations they encode. Knowledge of absolute duration is learned much later in development – many years after children first start using time words in speech – and in many children does not emerge until they have acquired formal definitions for the words. We conclude that associating words with the perception of duration does not come naturally to children, and that early intuitive meanings of time words are instead rooted in relative orderings, which children may infer from their use in speech.
Mobility allowance shuttle transit (MAST) services: MIP formulation and strengthening with logic constraints

Abstract We study a hybrid transportation system referred to as mobility allowance shuttle transit (MAST) where vehicles may deviate from a fixed path consisting of a few mandatory checkpoints to serve demand distributed within a proper service area. In this paper we propose a mixed integer programming (MIP) formulation for the static scheduling problem of a MAST type system. Since the problem is NP-Hard, we develop sets of logic cuts, by using reasonable assumptions on passengers’ behavior. The purpose of these constraints is to speed up the search for optimality by removing inefficient solutions from the original feasible region. Experiments show the effectiveness of the developed inequalities, achieving a reduction up to 90% of the CPU solving time for some of the instances.
A root locus-based flutter synthesis procedure

An efficient generalized constraint is proposed in the context of a nonlinear mathematical programming approach for the minimum weight design of wing structures for flutter considerations. The approach is based on a root locus analysis procedure that is better suited for flutter redesign than the conventionally used V-g method. The proposed flutter constraint does not require an actual computation of the flutter speed, allows prescription of meaningful margins of safety in the optimized design and lends itself to elegant computation of sensitivity information. The approach is implemented and results presented for representative structural models.
Hydrogen embrittlement of Ni3Al+B

An experimental study is conducted to verify the hypothesis that Ni3Al, which exhibits an L1(2) structure and remains ordered up to the melting point, would be severely embrittled by hydrogen and that this effect would be reversible. Unlike its effect on Ni, boron alloying is found not to suppress hydrogen embrittlement in NiAl + B. A continuous oxide layer, however, is an effective barrier to the entry of hydrogen in this material. The reduction of accomodative slip processes, and the resultant buildup of stresses at the grain boundaries, appears to be the most likely cause of hydrogen embrittlement in NiAl + B and other ordered alloys. 11 references.
Unimodality via Kronecker products

We present new proofs and generalizations of unimodality of the $$q$$ q -binomial coefficients $$\left( {\begin{array}{c}n\\ k\end{array}}\right) _q$$ n k q as polynomials in $$q$$ q . We use an algebraic approach by interpreting the differences between numbers of certain partitions as Kronecker coefficients of representations of $$S_n$$ S n . Other applications of this approach include strict unimodality of the diagonal $$q$$ q -binomial coefficients and unimodality of certain partition statistics.
Surface shape of two-dimensional granular piles

We study the surface shape of two-dimensional piles using experiments and a continuum theory for surface flows of granular materials (the BCRE equations). We first obtain an analytical solution to the BCRE equations with a simple transformation and show that the surface shapes thereby predicted are in good agreement with the experimental results. By means of such an analytical solution, we find that the formation of the curved tails at the bottom of such piles depends not only on the properties of the granular materials but also on the drift velocity of the grains within the rolling layer.
Counting rational curves of arbitrary shape in projective spaces

We present an approach to a large class of enumerative problems concerning rational curves in projective spaces. This approach uses analysis to obtain topological information about moduli spaces of stable maps. We demonstrate it by enumerating one-component rational curves with a triple point or a tacnodal point in the three-dimensional projective space and with a cusp in any projective space.
Old and new problems in the field of vapor‐liquid equilibria

A review is presented on vapor-liquid equilibria. Arnong the topics discussed are activity coefficients, consistency criteria, automatic computation, and gaseous mixtures. A bibliography of 18 references is included. (D.L.C.)
Active vibration control of a compliant structure using a magnetostrictive actuator

This paper presents work in progress concerning the development of a controller for active vibration control of a compliant structure using a magnetostrictive actuator. The paper describes the approach used to develop a model of the plant that includes both the actuator and cantilever beam considered for controller design. The active vibration control capabilities of a magnetostrictive actuator attached to a damped structure are considered. A linear model is assumed and adaptive filtering is used to identify actuator parameters. In addition, a Galerkin method is used to discretize the weak model of the compliant beam, which includes the influence of the attached magnetostrictive actuator. Special attention is paid to the interaction of the actuator and beam during the system identification efforts. An estimation of the model parameters is made through minimization of the beam's free end acceleration cost function. Finally, discussion of the initial observer and controller design effort is included.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Strongly coupled inorganic–nano-carbon hybrid materials for energy storage

The global shift of energy production from fossil fuels to renewable energy sources requires more efficient and reliable electrochemical energy storage devices. In particular, the development of electric or hydrogen powered vehicles calls for much-higher-performance batteries, supercapacitors and fuel cells than are currently available. In this review, we present an approach to synthesize electrochemical energy storage materials to form strongly coupled hybrids (SC-hybrids) of inorganic nanomaterials and novel graphitic nano-carbon materials such as carbon nanotubes and graphene, through nucleation and growth of nanoparticles at the functional groups of oxidized graphitic nano-carbon. We show that the inorganic–nano-carbon hybrid materials represent a new approach to synthesize electrode materials with higher electrochemical performance than traditional counterparts made by simple physical mixtures of electrochemically active inorganic particles and conducting carbon materials. The inorganic–nano-carbon hybrid materials are novel due to possible chemical bonding between inorganic nanoparticles and oxidized carbon, affording enhanced charge transport and increased rate capability of electrochemical materials without sacrificing specific capacity. Nano-carbon with various degrees of oxidation provides a novel substrate for nanoparticle nucleation and growth. The interactions between inorganic precursors and oxidized-carbon substrates provide a degree of control over the morphology, size and structure of the resulting inorganic nanoparticles. This paper reviews the recent development of inorganic–nano-carbon hybrid materials for electrochemical energy storage and conversion, including the preparation and functionalization of graphene sheets and carbon nanotubes to impart oxygen containing groups and defects, and methods of synthesis of nanoparticles of various morphologies on oxidized graphene and carbon nanotubes. We then review the applications of the SC-hybrid materials for high performance lithium ion batteries, rechargeable Li–S and Li–O2 batteries, supercapacitors and ultrafast Ni–Fe batteries, and new electrocatalysts for oxygen reduction, oxygen evolution and hydrogen evolution reactions.
Coupling of Lattice Boltzmann and Finite Element Methods for Fluid-Structure Interaction Application

In order to analyze the fluid-structure interaction between a flow and a flexible structure, an algorithm was presented to couple the lattice Boltzmann method (LBM) and the finite element method (FEM). The LBM was applied to the fluid dynamics while the FEM was applied to the structural dynamics. The two solution techniques were solved in a staggered manner, i.e., one solver after another. Continuity of the velocity and traction was applied at the interface boundaries between the fluid and structural domains. Furthermore, so as to make the fluid-structure interface boundary more flexible in terms of the computational modeling perspective, a technique was also introduced for the LBM so that the interface boundary might not coincide with the fluid lattice mesh. Some example problems were presented to demonstrate the developed techniques.
Regulation of the centrifugal interchange cycle in Saturn's inner magnetosphere

[1] Multifluid modeling of Saturn's magnetosphere produces the first numerical simulation showing the development of hot, tenuous plasma from the plasma sheet interchanging with cold, denser plasma from the inner magnetosphere. Individual injection events are seen regularly by Cassini, but with a single observation it is impossible to determine the global distribution. Multifluid simulations enable us to characterize the growth and development of not merely one injection event but show that it is a global process dependent on both the plasma distribution of ions from Enceladus and forcing by solar wind conditions. Development of the interchange arises in a fashion similar to a Rayleigh-Taylor instability, except that the heavy ions are being driven outward not by gravity but by centrifugal forces. Interplanetary magnetic field (IMF) parallel to the planetary magnetic field reduces centrifugal forcing, whereas antiparallel IMF increases the forcing, by altering the bowl-like shape of the plasma sheet. However, the interchange instability also develops under normally quiet parallel IMF conditions when the mass loading of the Enceladus torus is increased. The total number of interchange events is 1–2 higher for the antiparallel case versus the increased mass case. Interchange develops in the vicinity of 7 RS, and once the fingers of cold plasma reach ∼12–14 RS (close to the inner edge of the plasma sheet) they spread in the azimuthal direction, because of the fact that the magnetic field is too weak to keep the fingers solidly locked in rotation. The derived energy characteristics of the interchanging plasma are shown to be consistent with Cassini data.
On the Lusternik-Schnirelmann category of spaces with 2-dimensional fundamental group

The following inequality cat LS X ≤ cat LS Y + hd(X)-r r+1 holds for every locally trivial fibration f: X → Y between ANE spaces which admits a section and has the r-connected fiber, where hd(X) is the homotopical dimension of X. We apply this inequality to prove that cat LS X ≤ cd(π 1 (X)) + dim X - 1 2 for every complex X with cd(π 1 (X)) ≤ 2, where cd(iri(X)) denotes the cohomological dimension of the fundamental group of X.
Thermocapillary migration of liquid droplets in a temperature gradient in a density matched system

An experimental investigation of thermocapillary flow in droplets of a vegetable oil (partially hydrogenated soybean oil) immersed in silicone oil was conducted in a test cell with a heated top wall and a cooled bottom wall. The liquids are nearly immiscible and have equal densities at a temperature below the room temperature, thus providing a simulation of low-gravity conditions by reducing the buoyancy forces. The interfacial tension between the two oils was measured in the temperature range 20 to 50 C using a capillary tube and (d sigma)/(d T) was determined to be negative. Droplets ranging in sizes from 3 mm to 1 cm diameter were injected into the silicone oil. The vertical temperature profile in the bulk liquid (silicone oil) produces temperature variations along the interface which induce variations in the interfacial tension. The flow inside the droplet driven by the resulting interfacial shear stresses was observed using a laser light-sheet flow visualization technique. The flow direction is consistent with the sign of (d sigma)/(d T). The observed maximum surface velocities are compared to the theoretical predictions of Young et al. (1959).
Use of Material Tailoring to Improve Buckling Capacity of Elliptical Composite Cylinders

Discussed is the improvement of the axial buckling capacity of elliptical fiber-reinforced composite cylinders though material property tailoring by appropriately varying fiber orientation as a continuous function of circumferential position. The study is numerical in nature and relative to a baseline quasi-isotropic elliptical cylinder with the same geometry and the same number of composite layers, and therefore the same weight, increases in buckling capacity of 30% are predicted for what are considered small cylinders. Increases of 35% are predicted for larger cylinders. Several fiber angle variations with circumferential position are investigated, and each one results in improved buckling capacity. The scheme to determine the fiber angles as a function of circumferential position is based on an approximate buckling analysis of circular cylinders. Though not the primary point of the paper, intralaminar material failure and post-buckling collapse of the cylinders are also investigated to determine if the material tailoring scheme has a detrimental effect on those responses. It is found that prior to collapse no material failure is predicted. Upon collapse, generally speaking, failures due to high stresses perpendicular to the fibers are more prevalent in the tailored designs than for the baseline quasi-isotropic case. However, with some tailored designs no failures in the fiber direction are predicted, unlike the baseline case. Convergence of the numerical predictions is discussed, as is the effect of cylinder boundary conditions on the predicted improvement in buckling capacity.
Intramolecular Diels–Alder chemistry of 4-vinylimidazoles

An investigation of 4-vinylimidazoles as diene components in the intramolecular Diels–Alder reaction is described. In the course of these studies several parameters affecting the cycloaddition were evaluated including the nature of the imidazole protecting group, the type of dienophile and the linking group. These investigations established that amino linkers were generally more effective than either ethers or esters. In most cases, the cycloadditions were highly stereoselective, resulting in the formation of products derived from an anti transition state. The polysubstituted tetrahydrobenzimidazole core of the pyrrole-imidazole alkaloid ageliferin can be constructed through the use of pseudo dimeric 4-vinylimidazoles.
Enhancing tracer diffusivity by tuning interparticle interactions and coordination shell structure

This study uses a combination of stochastic optimization, statistical mechanical theory, and molecular simulation to test the extent to which the long-time dynamics of a single tracer particle can be enhanced by rationally modifying its interactions—and hence static correlations—with the other particles of a dense fluid. Specifically, a simulated annealing strategy is introduced that, when coupled with test-particle calculations from an accurate density functional theory, finds interactions that maximize either the tracer's partial molar excess entropy or a related pair-correlation measure (i.e., two quantities known to correlate with tracer diffusivity in other contexts). The optimized interactions have soft, Yukawa-like repulsions, which extend beyond the hard-sphere interaction and disrupt the coordination-shell cage structure surrounding the tracer. Molecular and Brownian dynamics simulations find that tracers with these additional soft repulsions can diffuse more than three times faster than bare hard spheres in a moderately supercooled fluid, despite the fact that the former appear considerably larger than the latter by conventional definitions of particle size.
Coherent electromagnetic processes in ultra-peripheral heavy-ion collisions

Abstract We report measurements for coherent ϱ 0 production, Auau → AuAuϱ 0 , and coherent ϱ 0 and e + e − pair production accompanied by mutual nuclear Coulomb excitation, AuAu→Au ∗ Au ∗ ϱ 0 and AuAu→Au ∗ Au ∗ +e + e − , in ultra-peripheral relativistic gold-gold collisions (UPC). We discuss transverse momentum, mass, and rapidity distributions. The two photon-process of e + e − pair production is an important probe of strong field QED because of the large coupling Zα = 0.6. At √ S NN =200 GeV, the e + e − production cross section agrees with lowest order QED calculations. The cross sections for coherent ϱ 0 production at √ S NN = 130 and 200 GeV are in agreement with theoretical predictions. The calculations for both, coherent e + e − and ϱ 0 production treat nuclear excitation as independent process.
Low Cost Thin-Film CdS-Based Solar Cells—Progress and Promise

The direct conversion of sunlight to electricity using thin film solar cells is potentially a low cost renewable source of energy. A major factor contributing to the low projected costs is the very small quantities of materials required as the active layers of the cells can be as little as 2 μm thick. The efficiency of solar cells will have to exceed ten percent to achieve economic power generation. Until 1976 no thin film solar cells with above seven percent efficiency in sunlight had been reported, but since then the Institute of Energy Conversion has successively reported 7.8, 8.55 and 9.15 percent. This paper will describe the loss minimization methodology utilized to achieve these increases in performance. Analysis shows that efficiencies as high as 14–16 percent for CdS-based solar cells are achievable. The research and development necessary to achieve these high efficiencies will be described. The feasibility of an extremely low cost manufacturing process capable of producing solar cells costing 250 dollars/kWatt will be discussed. Recent progress in development of low-cost thin-film devices shows great promise that direct conversion of sunlight to electricity can make a measurable contribution to the electrical energy supply both nationally and internationally.
Ni-Au: A testing ground for theories of phase stability

Abstract The theory of phase stability in the Ni-Au alloy system is a popular topic due to the large size mismatch between Ni and Au, which makes the effects of atomic relaxation critical and also to the fact that Ni-Au exhibits a phase separation tendency at low temperatures, but measurements at high-temperature show an ordering-type short-range order. We have clarified the wide disparity which exists in the previously calculated values of mixing energies and thermodynamic properties by computing ‘state-of-the-art’ energetics (full-potential, fully-relaxed LDA total energies) combined with ‘state-of-the-art’ statistics (k-space cluster expansion with Monte Carlo simulations) for the Ni-Au system. We find: (i) LDA provides accurate mixing energies of disordered Ni1− xAux alloys (Hmix ≤ + 100 meV/atom) provided that both atomic relaxation (a ~ 100 meV/atom effect) and short-range order (~ 25 meV/atom) are taken into account properly. (ii) Previous studies using empirical potentials or approximated LDA methods often underestimate the formation energy of ordered compounds and hence also underestimate the mixing energy of random alloys, (iii) Measured values of the total entropy of mixing combined with calculated values of the configurational entropy demonstrate that the non-configurational entropy in Ni-Au is large and leads to a significant reduction in miscibility gap temperature, (iv) The calculated short-range order agrees well with measurements and both predict ordering in the disordered phase, (v) Consequently, using inverse Monte Carlo to extract interaction energies from the measured/calculated short-range order in Ni-Au would result in interactions which would produce ordering-type mixing energies, in contradiction with both experimental measurements and precise LDA calculations.
Quaking Neutron Stars

Gravitational, magnetic, and superfluid forces can stress the crust of an evolving neutron star. Fracture of the crust under these stresses could affect the star's spin evolution and generate high-energy emission. We study the growth of strain in the crust of a spinning down, magnetized neutron star and examine the initiation of crust cracking (a starquake). In preliminary work in 1998 we studied a homogeneous model of a neutron star. Here we extend this work by considering a more realistic model of a solid, homogeneous crust afloat on a liquid core. In the limits of astrophysical interest, our new results qualitatively agree with those from the simpler model: the stellar crust fractures under shear stress at the rotational equator, matter moves to higher latitudes, and the star's oblateness is reduced. Magnetic stresses favor faults directed toward the magnetic poles. Thus our previous conclusions concerning the star's spin response still hold; namely, asymmetric redistribution of matter excites damped precession, which could ultimately lead to an increase in the spin-down torque. Starquakes associated with glitches could explain the permanent offsets in period derivative observed to follow glitches in at least three pulsars.
Corporate brand name changes and business restructuring: is the relationship complementary or substitutive?

Corporate brands are strategic assets for organizations, but it is difficult to understand the value added by corporate brand name changes because they often occur simultaneously with business restructuring initiatives. The authors test a framework that delineates the informational relationship between corporate name changes and business restructuring initiatives. The hypothesis is tested on a sample of jointly announced corporate name changes and business restructuring initiatives. The results show that jointly announced corporate name changes and business restructuring are significantly more informative than the sum of their individual effects. The results further suggest that the information complementarity arises because corporate brand name changes resolve uncertainty and help in coordinating business restructuring initiatives. The results do not support the view that corporate brand name changes are cosmetic and/or primarily signals for business restructuring. The study offers a promising research foundation for understanding the value of marketing actions announced jointly with other corporate events.
A stochastic hybrid system approach to aggregated load modeling for demand response

This abstract presents an unified framework for aggregated modeling of various responsive loads. The general model consists of coupled partial differential equations derived by drawing the connection with stochastic hybrid systems.
Improved Photometric Calibrations for Red Stars Observed with the SDSS Photometric Telescope

We present a new set of photometric transformations for red stars observed with the Sloan Digital Sky Survey (SDSS) 0.5 m Photometric Telescope (PT) and the SDSS 2.5 m telescope at the Apache Point Observatory in New Mexico. Nightly PT observations of US Naval Observatory standards are used to determine extinction corrections and calibration terms for SDSS 2.5 m photometry. Systematic differences between the PT and native SDSS 2.5 m ugriz photometry require conversions between the two systems which have previously been undefined for the reddest stars. By matching ~43,000 stars observed with both the PT and SDSS 2.5 m, we extend the present relations to include low-mass stars with colors 0.6 ≤ r - i ≤ 1.7. These corrections will allow us to place photometry of bright, low-mass trigonometric parallax stars previously observed with the PT on the 2.5 m system. We present new transformation equations and discuss applications of these data to future low-mass star studies using the SDSS.
Theoretical Perspectives on Proton-Coupled Electron Transfer Reactions

This Account presents a theoretical formulation for proton-coupled electron transfer reactions. The active electrons and transferring protons are treated quantum mechanically, and the free energy surfaces are obtained as functions of collective solvent coordinates corresponding to the proton and electron transfer reactions. Rate expressions have been derived in the relevant limits, and methodology for including the dynamical effects of the solvent and protein has been developed. This theoretical framework allows predictions of rates, mechanisms, and kinetic isotope effects for proton-coupled electron transfer reactions.
Cost-Function-Based Network Selection Strategy in Integrated Wireless and Mobile Networks

Wireless and mobile networks have experienced great success over the past few years. However, any single type of wireless and mobile network cannot provide all types of services, e.g., wide coverage and high bandwidth. An integrated wireless and mobile network is introduced by combining these different types of wireless and mobile networks, which can provide more comprehensive services. In an integrated wireless and mobile network, a mobile terminal that is equipped with heterogeneous network interfaces is capable of accessing all the available networks. Therefore, how to select a desired network is an important issue for the integrated wireless and mobile network. Although some network-selection strategies have been proposed, most of them are designed to meet a user's individual needs, such as the bandwidth, the access fee, or the power consumption. The system performance also has not been touched. In this paper, we propose a cost-function-based network selection (CFNS) strategy in an integrated wireless and mobile network from a system's perspective, which also considers a user's needs. We also analyze the system performance of the proposed network-selection strategy by using a theoretical model and extensive simulations. The results obtained show that the proposed network-selection strategy affects multiple system parameters, which needs to be handled carefully.
Provocative techniques should be used for the diagnosis of psychogenic nonepileptic seizures

Many epilepsy centers use provocative techniques (inductions) during EEG-video monitoring to aid in the diagnosis of psychogenic nonepileptic seizures. Provocative techniques are not always necessary, and they should only be used when they help establish the diagnosis. There are several situations where inductions have significant advantages. When attacks do not occur spontaneously, provocative techniques can turn an inconclusive evaluation into a diagnostic one. Triggering an attack with induction can shorten the evaluation, decreasing its cost and reducing waiting time in the monitoring unit. Patients with infrequent episodes (that do not occur frequently enough to obtain a spontaneous event during monitoring) can be scheduled for a brief outpatient monitoring with induction. In clinical scenarios where symptoms are consistent with a ''simple partial" seizure, the very presence of suggestibility is in itself a very strong additional argument to support a psychogenic etiology. The arguments against inductions are mainly based on ethical concerns. While these concerns have some validity, they are, in the real world, far outweighed by the alternatives. It is far more unethical to not obtain a definitive diagnosis when it would be possible, since the consequences of perpetuating the wrong diagnosis are many and serious. Even with placebo the benefits far outweigh the very minor ethical theoretical concerns, and the use of placebo is not even necessary. When correctly performed and interpreted, the specificity of inductions is over 90%. All tests have limitations, with some false positives and false negatives. Like all other tests, inductions must be used appropriately and with awareness of their limitations.
Geometric approximations of some Aloha-like stability regions

Most bounds on the stability region of Aloha give necessary and sufficient conditions for the stability of an arrival rate vector under a specific contention probability (control) vector. But such results do not yield easy-to-check bounds on the overall Aloha stability region because they potentially require checking membership in an uncountably infinite number of sets parameterized by each possible control vector. In this paper we consider an important specific inner bound on Aloha that has this property of difficulty to check membership in the set. We provide ellipsoids (for which membership is easy-to-check) that we conjecture are inner and outer bounds on this set. We also study the set of controls that stabilize a fixed arrival rate vector; this set is shown to be a convex set.
Mapping Large-Scale Gaseous Outflows in Ultraluminous Galaxies with Keck II ESI Spectra: Variations in Outflow Velocity with Galactic Mass

Measurements of interstellar Na I λλ5890, 5896 absorption lines in 18 ultraluminous infrared galaxies (ULIGs) have been combined with published Na I data, to reassess the dependence of galactic outflow speeds on starburst luminosity and galactic mass. The Doppler shifts reveal outflows of relatively cool gas in 15 of 18 ULIGs with an average outflow speed at the line center of 330 ± 100 km s-1. The relation between outflow speed and star formation rate (SFR), defined by the distribution's upper envelope over 4 orders of magnitude in SFR, demonstrates that winds from more luminous starbursts accelerate interstellar gas to higher speeds roughly as v ∝ SFR0.35. This result is surprising since, in the traditional model for starburst-driven winds, these relatively cool gas clouds are accelerated by the ram pressure of a hot, supernova-heated wind that exhibits weak (if any) X-ray temperature variation with increasing galactic mass. The lack of evidence for much hotter winds is partly a sensitivity issue, but the Na I velocities in ultraluminous starbursts actually are consistent with acceleration by the tepid wind, indicating that a hotter component is unlikely to dominate the momentum flux. The Na I velocities in the dwarf starburst winds do not reach the terminal velocity of a hot wind at the measured temperature of kT ~ 0.73 keV, a result that could be interpreted simply as evidence that the hot superbubbles are too confined in dwarf starbursts to generate a free-flowing wind. A dynamically motivated scenario, however, is that the dwarf starburst winds simply lack enough momentum to accelerate the clouds to the velocity of the hot wind. Among the subsample of starbursts with well-constrained dynamical masses, the terminal outflow velocities are always found to approach the galactic escape velocity. Motivated by a similar scaling relation for stellar winds, the galactic Eddington luminosity for dusty starbursts is shown to be within the range measured for ULIGs. If radiation pressure on dust grains, coupled to the cool wind, is indeed important for galactic wind dynamics, then feedback is stronger in massive galaxies than previously thought, helping shape the high-mass end of the galaxy luminosity function. Regardless of the nature of the acceleration mechanism in ULIGs, the mass flux of cool gas estimated from these data demonstrates that starburst-driven winds transport significant gas during the assembly stage of field elliptical galaxies, a factor that helps explain the rapid decline in SFR in these systems inferred from elemental abundance ratios.
DIRECT CONTACT AMONG GALACTIC CIVILIZATIONS BY RELATIVISTIC INTERSTELLAR SPACEFLIGHT

Abstract An estimate of the number of advanced technical civilizations on planets of other stars depends on our knowledge of the rate of star formation; the frequency of favorably situated planets ; the probabilities of the origins of life, of intelligence and of technical civilization ; and the lifetimes of technical civilizations. These parameters are poorly known. The estimates of the present paper lead to ∼106 extant advanced technical civilizations in our Galaxy. The most probable distance to the nearest such community is then several hundred light years. Interstellar spaceflight at relativistic velocities has several obvious advantages over electromagnetic communication among these civilizations. One striking feature is that with uniform acceleration of 1 g to the midpoint of the journey, and uniform deceleration thereafter, all points in the Galaxy are accessible within the lifetime of a human crew, due to relativistic time dilation. Some of the technical problems in the construction of starships capable of relativistic velocities are discussed. It is concluded that with nuclear staging, fusion reactors, and the Bussard interstellar ramjet, no fundamental energetic problems exist for relativistic interstellar spaceflight. We assume that there exists in the Galaxy a loosely integrated community of diverse civilizations, cooperating in the exploration and sampling of astronomical objects and their inhabitants. If each such advanced civilization launches one interstellar vehicle per year, the mean time interval between samplings of an average star would be 105 years, that between samplings of a planetary system with intelligent life would be 104 years, and that between sampling of another advanced civilization would be 103 years. It follows that there is the statistical likelihood that Earth was visited by an advanced extraterrestrial civilization at least once during historical times. There are serious difficulties in demonstrating such a contact by ancient writings and iconography alone. Nevertheless, there are legends which might profitably be studied in this context. Bases or other artifacts of interstellar spacefaring civilizations might also exist elsewhere in the solar system. The conclusions of the present paper are clearly provisional.
Regioselective iron-catalyzed decarboxylative allylic etherification.

An anionic iron complex catalyzes the decarboxylative allylation of phenols to form allylic ethers in high yield. The allylation is regioselective rather than regiospecific. This suggests that the allylation proceeds through π-allyl iron intermediates in contrast to related allylations of carbon nucleophiles that have been proposed to proceed via σ-allyl complexes. Ultimately, iron catalysts have the potential to replace more expensive palladium catalysts that are typically utilized for decarboxylative couplings.
NEAR-INFRARED INTERFEROMETRIC MEASUREMENTS OF HERBIG Ae/Be STARS

We have observed the Herbig Ae/Be sources AB Aur, VV Ser, V1685 Cyg (BD +40°4124), AS 442, and MWC 1080 with the Palomar Testbed Interferometer, obtaining the longest baseline near-IR interferometric observations of this class of objects. All of the sources are resolved at 2.2 μm with angular size scales generally 5 mas, consistent with the only previous near-IR interferometric measurements of Herbig Ae/Be stars, by Millan-Gabet and collaborators. We determine the angular size scales and orientations predicted by uniform-disk, Gaussian, ring, and accretion disk models. Although it is difficult to distinguish different radial distributions, we are able to place firm constraints on the inclinations of these models, and our measurements are the first that show evidence for significantly inclined morphologies. In addition, the derived angular sizes for the early-type Herbig Be stars in our sample, V1685 Cyg and MWC 1080, agree reasonably well with those predicted by the face-on accretion disk models used by Hillenbrand and collaborators to explain observed spectral energy distributions. In contrast, our data for the later-type sources AB Aur, VV Ser, and AS 442 are somewhat inconsistent with these models and may be explained better through the puffed-up inner disk models of Dullemond and collaborators.
A Markov-type inequality for arbitrary plane continua

Markov's inequality is sup |f'| ≤(degf) 2 sup |f|, [-1,1] [-1,1] for all polynomials f. We prove a precise version of this inequality with an arbitrary continuum in the complex plane instead of the interval [-1,1].
Preparation of 2-[1-Phenyl-1H-pyrazol-5-yl]benzoic Acids from Dilithiated C(α),N-Phenylhydrazones and Methyl Hydrogen Phthalate

Select C(α),N-phenylhydrazones were dilithiated with excess lithium diisopropylamide to their dianion-type intermediates followed by condensation with methyl hydrogen phthalate. The resulting C-acylated hydrazones were not isolated but acid cyclized directly to afford new substituted 2-(1-phenyl-1H-pyrazol-5-yl)benzoic acids.
Entry, Its Deterrence, and Its Accommodation: A Study of the U. S. Photographic Film Industry

This work, set in the "new empirical industrial organization" framework (Bresnahan, 1987), examines firm-level demand-based and cost-based explanations for entry and accommodation strategies in the U.S. photographic film industry. I first estimate preentry and postentry market structures. Then, using the estimated demand, cost, and market conduct parameters, I show how entry by Fuji Photo, or lack thereof by others, is a function of two market structures. I also show how market structure and conduct, and changes in them over the pre- and postentry periods, are, in turn, functions of entry, its deterrence, and it accommodation.
Limited computational ability and social security

We revisit the role of social security in countering inadequate saving for retirement. We compute the optimal social security tax rate for households who lack the computational ability to solve dynamic optimization problems. Instead, they follow the simple rule of thumb of consuming and saving a fixed fraction of disposable income. This departs from the tradition of computing the optimal tax rate when households suffer from some type of behavioral bias yet possess the ability to solve dynamic optimization problems. Our general equilibrium model is calibrated to the moments of the distribution of saving rates in the US, and our results are generally supportive of a social security program as large as the one in the US.
Dr. Leo Replies.

Sir: One would naturally question the suggestion that an analgesic, e.g., acetaminophen or an opiate, that reduces pain severity in a patient with chronic pain, and thereby reduces the patient's dysphoria, would be implied to have an antidepressant property. It is in this context that the article by Leo and Barkin was written.1
Towards the total synthesis of FD-838: modular enantioselective assembly of the core

A rapid assembly of the tetracyclic core of FD-838, featuring a catalytic asymmetric Stetter reaction, is described.
Income Prospects and Age at Marriage

This paper provides an empirical investigation of a theoretical model of the marriage market. In the model, women are valued more for their ability to bear children and men are valued more for their ability to make money. Men cannot reveal their labor market ability to potential spouses until they enter the labor force. At the same time, the relevant information for evaluating females as spouses is revealed at a younger age. The model predicts that the income of males will be positively associated with age-at-first-marriage. We find empirical support for the model. However, we also find the association between male earnings and age-at-first-marriage becomes negative for those who married after age 30, which was not predicted by the model. Consistent with the model, we do not find a strong relationship between earnings and age-at-first-marriage among females.
Copper(II) complexes of 2-dimethylamino-3-picoline N-oxide (3MDM) and 2 diethylamino-3-picoline N-oxide (3MDE)

Abstract Copper(II) complexes with 2-dimethylamino-3- picoline N-oxide (3MDM) and 2-diethylamino-3- picoline N-oxide (3MDE) have been prepared from the following salts: tetrafluoroborate, nitrate, chloride and bromide. Solids of the general formula [CuL 2 ](BF 4 ) 2 and [CuLX 2 ] where L=3MDM and 3MDE and X=NO 3 , Cl and Br were characterized using spectral methods ( i.e., IR, UV-Vis and ESR). Both of these N -oxides coordinate as bidentate ligands via the N -oxide oxygen and the amine nitrogen in all of the complexes. The steric effect of the diethylamino group is larger compared to the dimethylamino in the four pairs of complexes involving the different anions. Considerable distortion compared to the complexes of the analogous pyridine N -oxide ligands also occurs due to the ring methyl group.