cssi/SciSciGPT-SciSciNet huggingface dataset:
Regulation and the Nature of the Firm: The Case of U.S. Regional Airlines

AbstractIn his pathbreaking article “The Nature of the Firm,” Ronald H. Coase postulated that the structure of production was determined by the comparative advantage between contracting and hierarchy in securing and coordinating complementary resources for production. While Coase considered the possibility that regulation might also influence the way production is structured, he considered the problem only very generally. This paper suggests that airline deregulation has profoundly affected the structure of firms that operate airline networks by affecting contractual conditions under which airlines purchase labor inputs, removing constraints on the extent and nature of the firm’s route network, and changing the competitive environment in which airline firms operate. Where a stable uniform firm structure existed under regulation, airline networks now are organized with a variety of firm structures, and individual networks have changed as particular conditions have changed over time. No single structure dom...
Mechanisms and rate laws for oxygen exchange on mixed-conducting oxide surfaces

Transition metal oxides with mobile electrons and oxygen ions (mixed conductors) constitute a broad class of materials that include selective oxidation catalysts, high-temperature electrocatalysts, and ion-transport membrane materials. Although the thermodynamic and transport properties of mixed conductors are generally understood, a consensus has not yet emerged regarding the mechanisms and rate laws governing exchange of oxygen with the bulk at the gas-exposed surface. To aid interpretation of existing kinetic data, and generate testable hypotheses for further research, this paper outlines a framework for predicting O2 reduction rate laws based on specific reaction mechanisms. Based on nonequilibrium thermodynamics and transition state theory, this framework yields rate laws that are rigorously consistent with thermodynamics, yet allow rates of individual steps to be developed in terms of simple mass action laws, where appropriate. This framework is used to reexamine equilibrium oxygen-exchange kinetics reported for electron-rich perovskite mixed conductors La1−xSrxCoO3−δ (LSC) and La1−xSrxFeO3−δ (LSF), which have a metallic and a semiconducting band structure, respectively. Our analysis suggests that metallic band structure may play an important role in catalysis by stabilizing physisorbed O2 on the surface. We also show that equilibrium surface exchange rates (as measured by 18O/16O isotopes, concentration steps, impedance, etc.) are generally only weak indicators of mechanism, and emphasize the need for kinetic data involving moderate to large displacements from equilibrium.
Application of evaluated fission-product delayed-neutron precursor data in reactor kinetics calculations

Abstract Evaluated fission-product yield and decay data have been used to describe 105 delayed neutron precursors explicitly in point reactor kinetics calculations. Results calculated for 235U thermal fission show that rod-drop reactivity values obtained from kinetics calculations with 6-group precursor data are considerably higher than those calculated with explicit delayed-neutron precursor data. The calculated kinetics associated with positive reactivity steps are significantly different.
Total Synthesis of d,l-Isospongiadiol: An Intramolecular Radical Cascade Approach to Furanoditerpenes.

A stereoselective oxidative free-radical cyclization of β-keto ester polyenes 7 and 19 has been accomplished as a one-step entry to the tricarbocyclic synthons 8 and 21 which contain five and six stereogenic centers, respectively. These key synthons possessing an axial carboethoxy group at C-4 were ultimately converted to the spongian skeleton (8 → 14 and 21 → 25 → 14). The synthesis of d,l-isospongiadiol (3) from the common intermediate 14 was realized after introduction of the 2α-hydroxy group in the spongian A-ring via epoxidation of silyl enol ether 28 and subsequent desilylation.
Universal contingent claims in a general market environment and multiplicative measures: Examples and applications

Abstract We present and further develop the concept of a universal contingent claim introduced by the author in 1995. This concept provides a unified framework for the analysis of a wide class of financial derivatives. A universal contingent claim describes the time evolution of a contingent payoff. In the simplest case of a European contingent claim, this time evolution is given by a family of nonnegative linear operators, the valuation operators. For more complex contingent claims, the time evolution that is given by the valuation operators can be interrupted by discrete or continuous activation of external influences that are described by, generally speaking, nonlinear operators, the activation operators. For example, Bermudan and American contingent claims represent discretely and continuously activated universal contingent claims with the activation operators being the nonlinear maximum operators. We show that the value of a universal contingent claim is given by a multiplicative measure introduced by the author in 1995. Roughly speaking, a multiplicative measure is an operator-valued (in general, an abstract measure with values in a partial monoid) function on a semiring of sets which is multiplicative on the union of disjoint sets. We also show that the value of a universal contingent claim is determined by a, generally speaking, impulsive semilinear evolution equation.
The PI3K/Akt1 pathway enhances steady-state levels of FANCL

Fanconi anemia hematopoietic stem cells display poor self-renewal capacity when subjected to a variety of cellular stress. This phenotype raises the question of whether the Fanconi anemia proteins are stabilized or recruited as part of a stress response and protect against stem cell loss. Here we provide evidence that FANCL, the E3 ubiquitin ligase of the Fanconi anemia pathway, is constitutively targeted for degradation by the proteasome. We confirm biochemically that FANCL is polyubiquitinated with Lys-48-linked chains. Evaluation of a series of N-terminal-deletion mutants showed that FANCL's E2-like fold may direct ubiquitination. In addition, our studies showed that FANCL is stabilized in a complex with axin1 when glycogen synthase kinase-3β is overexpressed. This result leads us to investigate the potential regulation of FANCL by upstream signaling pathways known to regulate glycogen synthase kinase-3β. We report that constitutively active, myristoylated-Akt increases FANCL protein level by reducing polyubiquitination of FANCL. Two-dimensional PAGE analysis shows that acidic forms of FANCL, some of which are phospho-FANCL, are not subject to polyubiquitination. These results indicate that a signal transduction pathway involved in self-renewal and survival of hematopoietic stem cells also functions to stabilize FANCL and suggests that FANCL participates directly in support of stem cell function.
Monodisperse Metal Nanoparticle Catalysts: Synthesis, Characterizations, and Molecular Studies Under Reaction Conditions

We aim to develop novel catalysts that exhibit high activity, selectivity and stability under real catalytic conditions. In the recent decades, the fast development of nanoscience and nanotechnology has allowed synthesis of nanoparticles with well-defined size, shape and composition using colloidal methods. Utilization of mesoporous oxide supports effectively prevents the nanoparticles from aggregating at high temperatures and high pressures. Nanoparticles of less than 2 nm sizes were found to show unique activity and selectivity during reactions, which was due to the special surface electronic structure and atomic arrangements that are present at small particle surfaces. While oxide support materials are employed to stabilize metal nanoparticles under working conditions, the supports are also known to strongly interact with the metals through encapsulation, adsorbate spillover, and charge transfer. These factors change the catalytic performance of the metal catalysts as well as the conductivity of oxides. The employment of new in situ techniques, mainly high-pressure scanning tunneling microscopy (HPSTM) and ambient-pressure X-ray photoelectron spectroscopy (APXPS) allows the determination of the surface structure and chemical states under reaction conditions. HPSTM has identified the importance of both adsorbate mobility to catalytic turnovers and the metal substrate reconstruction driven by gaseous reactants such as CO and O2. APXPS is able to monitor both reacting species at catalyst surfaces and the oxidation state of the catalyst while it is being exposed to gases. The surface composition of bimetallic nanoparticles depends on whether the catalysts are under oxidizing or reducing conditions, which is further correlated with the catalysis by the bimetallic catalytic systems. The product selectivity in multipath reactions correlates with the size and shape of monodisperse metal nanoparticle catalysts in structure sensitive reactions.
Weak convergence of the scaled median of independent Brownian motions

We consider the median of n independent Brownian motions, denoted by M n (t), and show that $$\sqrt{n}\,M_n$$ converges weakly to a centered Gaussian process. The chief difficulty is establishing tightness, which is proved through direct estimates on the increments of the median process. An explicit formula is given for the covariance function of the limit process. The limit process is also shown to be Holder continuous with exponent γ for all γ < 1/4.
On exact supersymmetry in DLCQ

Abstract In recent years a supersymmetric form of discrete light-cone quantization (hereafter `SDLCQ') has emerged as a very powerful tool for solving supersymmetric field theories. In this scheme, one calculates the light-cone supercharge with respect to a discretized light-cone Fock basis, instead of working with the light-cone Hamiltonian. This procedure has the advantage of preserving supersymmetry even in the discretized theory, and eliminates the need for explicit renormalizations in 1+1 dimensions. In order to compare the usual DLCQ prescription with the supersymmetric prescription, we consider two dimensional SU( N ) Yang-Mills theory coupled to a massive adjoint Majorana fermion, which is known to be supersymmetric at a particular value of the fermion mass. After studying how singular-valued amplitudes and intermediate zero momentum modes are regularized in both schemes, we are able to establish a precise connection between conventional DLCQ and its supersymmetric extension, SDLCQ. In particular, we derive the explicit form of the (irrelevant) interaction that renders the DLCQ formulation of the theory exactly supersymmetric for any light-cone compactification. We check our analytical results via a numerical procedure, and discuss the relevance of this interaction when supersymmetry is explicitly broken.
The Origin of the Galactic Center Nonthermal Radio Filaments: Young Stellar Clusters

The unusual class of magnetized nonthermal radio filaments, threads, and streaks, with their unique physical characteristics, is found only within the inner couple of degrees of the Galactic center. Also, a number of young, mass-losing, and rare stellar clusters are recognized as lying in the Galactic center region. The latter characteristic of the Galactic center region is used to explain the origin of the nonthermal radio filaments. We consider a mechanism in which the collective winds of massive W-R and OB stars within a dense stellar environment produce shock waves that can accelerate particles to relativistic energies. This mechanism is an extension of a model originally proposed in 1996 by Rosner & Bodo, who suggested that energetic nonthermal particles are produced in a terminal shock of mass-losing stars. The large-scale distribution of the magnetic field in the context of this model is argued to be neither poloidal in geometry nor pervasive throughout the Galactic center region.
Recommendations for research to develop guidelines for the use of wetlands to control rural nonpoint source pollution

Abstract Natural wetlands should not be used to reduce rural nonpoint source (NPS) problems. Properly designed restored or created wetlands, however, can be used for this purpose in many agricultural landscapes. Agricultural landscapes in which wetlands can be easily restored are the most suitable areas. Major technical issues that need to be resolved before effective and realistic guidelines can be developed for using restored wetlands to reduce NPS pollution include: (1) the effects of contaminants, particularly sediments and pesticides, on restored wetlands; (2) the fate of organic contaminants in restored wetlands; (3) the development of site selection criteria; and (4) the development of design criteria. There are also many social, economic, and political barriers to using restored wetlands. Social and economic issues that need to be resolved include: (1) what is the most appropriate landscape unit for wetland restoration programs? (2) where should wetlands be sited?; (3) who will make siting decisions?; (4) how can landowner cooperation for restoration programs be obtained?; (5) who will pay for wetland restorations?; and (6) how cost effective is this approach? Watersheds are recommended as the natural landscape unit for planning, implementing, and administering restoration projects. Eight different research projects are identified: five technical projects (watershed-level demonstration projects, effects of contaminants on wetlands, suitainable loading rates for contaminants, landscape or watershed simulation models, and site selection and design criteria for restored wetlands) and three economic and social projects (attitudes of farmers and rural leaders, legal and public policy implications, and economic costs and benefits).
Determination of the Primordial Magnetic Field Power Spectrum by Faraday Rotation Correlations

This paper introduces the formalism which connects between rotation measure (RM) measurements for extragalactic sources and the cosmological magnetic field power spectrum. It is shown that the amplitude and shape of the cosmological magnetic field power spectrum can be constrained by using a few hundred radio sources, for which Faraday RMs are available. This constraint is of the form Brms 1 × (2.6 × 10-7 cm -->−3/b]) h nG on ~10-50 h-1 Mpc scales, with b the average baryon density and h the Hubble parameter in units of 100 km s-1 Mpc-1. The constraint is superior to and supersedes any other constraint that comes from either cosmic microwave background (CMB) fluctuations, baryonic nucleosynthesis, or the first two multipoles of the magnetic field expansion. The most adequate method for the constraint calculation uses the Bayesian approach to the maximum likelihood function. I demonstrate the ability to detect such magnetic fields by constructing simulations of the field and mimicking observations. This procedure also provides error estimates for the derived quantities. The two main noise contributions due to the Galactic RM and the internal RM are treated in a statistical way following an evaluation of their distribution. For a range of magnetic field power spectra with power indices -1 ≤ n ≤ 1 in a flat cosmology (Ωm = 1) we estimate the signal-to-noise ratio, Q, for limits on the magnetic field Brms on a ~50 h-1 Mpc scale. Employing one patch of a few square degrees on the sky with source number density nsrc, an approximate estimate yields Q 3(Brms/1 nG)(nsrc/50 deg-2)(2.6 × 10-7 cm -->−3/b) h. An all-sky coverage, with a much sparser but carefully tailored sample of ~500 sources, yields Q 1 with the same scaling. An ideal combination of small densely sampled patches and sparse all-sky coverage yields Q 3 with better constraints for the power index. All of these estimates are corroborated by the simulations.
Formation and optical properties of cylindrical gold nanoshells on silica and titania nanorods

Metal-insulator core-shell structures have been demonstrated to have interesting and tunable optical properties. Systems previously investigated include silica-capped gold particles and gold shells surrounding silica particles. However, many of the systems studied so far have been spherical (or zero-dimensional). Thus, it would be of interest to look at the synthesis and optical properties of one-dimensional (i.e., rodlike) nanostructures. In this paper, the authors present and discuss the formation and properties of silica and titania nanorods encapsulated with a thin gold shell. Nanorods of silica and titania ∼10 μm in length and with diameters ∼ 90-200 nm are made by combining sol-gel electrophoresis with a suitable template. After removing the template at high temperature, the surface of the rods is re-hydrolyzed by heating in water. 3-Aminopropyltrimethoxysilane is reacted with the surface hydroxyl groups, self-assembling amine functionality on the surface of the rods. These groups act as anchoring sites for the gold, which forms a thin shell around the oxide nanorod. UV-vis absorbance spectra of these samples are analyzed to determine the relationships between shell thickness, core size, core material, and properties.
On Continuous Moyal Product Structure in String Field Theory

We consider a diagonalization of Witten's star product for a ghost system of arbitrary background charge and Grassmann parity. To this end we use a bosonized formulation of such systems and a spectral analysis of Neumann matrices. We further identify a continuous Moyal product structure for a combined ghosts+matter system. The normalization of multiplication kernel is discussed.
Dark matter and the CACTUS gamma-ray excess from Draco

The CACTUS atmospheric Cherenkov telescope collaboration recently reported a gamma-ray excess from the Draco dwarf spheroidal galaxy. Draco features a very low gas content and a large mass-to-light ratio, suggesting as a possible explanation annihilation of weakly interacting massive particles (WIMPs) in the Draco dark-matter halo. We show that with improved angular resolution, future measurements can determine whether the halo is cored or cuspy, as well as its scale radius. We find the relevant WIMP masses and annihilation cross sections and show that supersymmetric models can account for the required gamma-ray flux. The annihilation cross section range is found to be not compatible with a standard thermal relic dark-matter production. We compute for these supersymmetric models the resulting Draco gamma-ray flux in the GLAST energy range and the rates for direct neutralino detection and for the flux of neutrinos from neutralino annihilation in the Sun. We also discuss the possibility that the bulk of the signal detected by CACTUS comes from direct WIMP annihilation to two photons and point out that a decaying-dark-matter scenario for Draco is not compatible with the gamma-ray flux from the Galactic centre and in the diffuse gamma-ray background.
A Study of Nine High-Redshift Clusters of Galaxies. I. The Survey

We present a description of the observations and data reduction procedures for an extensive spectroscopic and multiband photometric study of nine high-redshift, optically selected cluster candidates. The primary goal of the survey is to establish new constraints on cluster and galaxy evolution, with specific emphasis on the evolution of galaxy morphology and on the star formation history of the galaxies within and around distant clusters. We have measured 892 new redshifts for galaxies with R ≤ 23.3. The data will also serve as deep probes of the foreground and background large-scale structures. The observations include broadband optical imaging and spectroscopy with the Low Resolution Imaging Spectrograph at the 10 m W. M. Keck Observatory telescope; K-band imaging with the IRIM camera at the 4 m Kitt Peak National Observatory telescope; and deep, high angular resolution imaging with the Wide Field Planetary Camera 2 on board the Hubble Space Telescope. We also describe the procedures used to obtain morphological information. We have established that six of the nine cluster candidates are indeed real space density enhancements and are representative of those typically associated with clusters of galaxies. The remaining three candidates appear to be projections of several smaller groups at widely separated distances. This success rate is consistent with estimates of the false-positive rate in two-dimensional optical high-z cluster searches.
Patterns and statistics of in-water polarization under conditions of linear and nonlinear ocean surface waves

[1] We study the polarization properties of the light field under a dynamic ocean surface using realistic linear and nonlinear ocean surface waves. The three-dimensional polarized radiative transfer of the dynamic ocean–atmosphere system is considered using a Monte Carlo vector radiative transfer simulation for arbitrary depth. The program is validated with measurement data taken in Hawaii during the Radiance in a Dynamic Ocean project. The main focus of this study is the influence of the wind-driven ocean waves on the polarization patterns and statistics at different optical depths under various conditions of light wavelength and solar incidence. Of special interest is the effect of the nonlinearity of the surface waves on the polarization statistics. To facilitate the study, phase-resolved direct simulations of the linear and nonlinear surface wavefields are performed using a high-order spectral method. The results show that the time-averaged degree of polarization within the Snell's window is dependent on the mean square slope of the ocean surface. Higher mean square slope, or wind speed, leads to a smaller degree of polarization. At the same time, the variability of the degree of polarization has a strong dependence on the surface roughness. A rougher ocean surface induces higher variability of the degree of polarization. The effect of wave nonlinearity can be neglected for the mean value of polarization, but is manifested in the variability of the degree of polarization, with a general increase in the variance with increasing wave nonlinearity. The present findings provide possible mechanisms for characterizing the dynamic ocean surface based on underwater polarized light measurements.
Chaotic motion of an array of vortices above a flat wall

The trajectories of three inviscid point vortices above a flat wall were investigated numerically. The behavior of the trajectories was characterized by detailed power spectra, phase portraits, Poincare sections, and estimates of the Lyapunov exponent spectrum. For certain initial conditions, the trajectories are regular and confined to a two‐torus in phase space. However, chaotic behavior that sets in as one of the vortices is initially placed closer to the unstable point of the system. In the chaotic regime, the system also exhibits large scale intermittency. Analytical expressions for the near‐ and far‐field noise, generated by the motion of the vortices, were also obtained. It was found that in the presence of a flat boundary, this motion does not contribute to any dipole field noise radiation, but is characterized by a quadrupole structure to leading order. The near‐field pressure was computed numerically and it was found that the chaotic behavior of the vortex trajectories results in broadband noise.
A NOTE ON DEL PEZZO FIBRATIONS OF DEGREE 1

Abstract The purpose of this paper is to extend the result in Park (Park, J. (2001). Birational maps of del Pezzo fibrations. J. Reine Angew. Math. 538:213–221) in the case of del Pezzo fibrations of degree 1. To this end we investigate the anticanonical linear systems of del Pezzo surfaces of degree 1. We then classify all possible effective anticanonical divisors on Gorenstein del Pezzo surfaces of degree 1 with canonical singularities.
Emission rates, the correspondence principle and the information paradox

Abstract When we vary the moduli of a compactification it may become entropically favourable at some point for a state of branes and strings to rearrange itself into a new configuration. We observe that for the elementary string with two large charges such a rearrangement happens at the ‘correspondence point’ where the string becomes a black hole. For smaller couplings it is entropically favourable for the excitations to be vibrations of the string, while for larger couplings the favoured excitations are pairs of solitonic 5-branes attached to the string; this helps resolve some recently noted difficulties with matching emission properties of the string to emission properties of the black hole. We also examine the change of state when a black hole is placed in a space-time with an additional compact direction, and the size of this direction is varied. These studies suggest a mechanism that might help resolve the information paradox.
Some Practical Considerations When Converting a Linearly Administered Test to an Adaptive Format

“We seek the truth and will endure the consequences.” Charles Seymour President of Yale (1937–1950)
Imprint of SNO neutral current data on the solar neutrino problem

Abstract We perform a global analysis in the framework of two active neutrino oscillations of all solar neutrino data, including the recent SNO day and night spectra (comprised of the charged current (CC), elastic scattering (ES) and neutral current (NC) events), the Super-Kamiokande (SK) day and night spectra (from 1496 days) and the updated SAGE results. We find that the Large Mixing Angle (LMA) solution is selected at the 99% C.L.; the best-fit parameters are Δm 2 =5.6×10 −5 eV 2 and θ =32°. No solutions with θ ⩾ π /4 are allowed at the 5 σ C.L. Oscillations to a pure sterile state are excluded at 5.3 σ , but a sizeable sterile neutrino component could still be present in the solar flux.
Analysis of Feeder Pig Auction Price Differentials

Several physical characteristics are important in pricing feeder pigs. This study identifies and estimates the discounts associated with various characteristics. Weight, lot size, health and lot uniformity were important physical traits affecting feeder pig price differentials. In addition, time of sale, changes in expected finished hog prices and fluctuations in expected feeder costs of finishing the pigs had significant impacts on feeder pig prices over time.
Why do grain boundaries exhibit finite facet lengths

Uniform finite facets are frequently observed at grain boundaries (GBs) and are usually attributed to equilibrium stabilization by GB stress. We report calculations for an aluminum twin GB using density functional theory, the embedded-atom method, and continuum elasticity theory. These methods show that GB stress is much too small to stabilize finite facets, suggesting that the usual explanation is incorrect.
On the Structure of Relativistic Collisionless Shocks in Electron-Ion Plasmas

Relativistic collisionless shocks in electron-ion plasmas are thought to occur in the afterglow phase of gamma-ray bursts (GRBs) and in other environments where relativistic flows interact with the interstellar medium. A particular regime of shocks in an unmagnetized plasma has generated much interest for GRB applications. In this Letter, we present ab initio particle-in-cell simulations of unmagnetized relativistic electron-ion shocks. Using long-term 2.5-dimensional simulations with ion-electron mass ratios from 16 to 1000, we resolve the shock formation and reach a steady state shock structure beyond the initial transient. We find that even at high ion-electron mass ratios initially unmagnetized shocks can be effectively mediated by the ion Weibel instability with a typical shock thickness of ~20 ion skin depths. Upstream of the shock, the interaction with merging ion current filaments heats the electron component, so that the postshock flow achieves near-equipartition between the ions and electrons, with the electron temperature reaching 50% of the ion temperature. This energy exchange helps to explain the large electron energy fraction inferred from GRB afterglow observations.
Changing looks and changing “discrimination”: The beauty of economists

Abstract Using candidates' multiple appearances in elections in a professional association with different photographs accompanying ballots, I show that exogenous increases in beauty raise chances of electoral success. The outcomes do not stem from correlations of ascriptive characteristics with unchanging unobserved differences in productivity-enhancing characteristics.
Iron(III) tosylate catalyzed synthesis of 3,4-dihydropyrimidin-2(1H)-ones/thiones via the Biginelli reaction

The synthesis of dihydropyrimidinones and dihydropyrimidine thiones has attracted interest due to their biological activities. A common method for their synthesis is the Biginelli reaction, which is a one-pot condensation of an aryl aldehyde, urea (or thiourea), and ethyl acetoacetate. The Biginelli reaction is typically catalyzed by a Bronsted or Lewis acid. However, many of these catalysts such as BF3·Et2O and AlCl3 are corrosive and/or toxic. Our continued interest in environmentally friendly organic synthesis prompted us to investigate the utility of iron(III) tosylate as a catalyst for the Biginelli reaction. The use of acetals in the Biginelli reaction is also reported. Iron(III) tosylate is an attractive catalyst for the Biginelli reaction because of its low cost, low toxicity, and ease of handling.
Hydrogen-bond acidic polymers for chemical vapor sensing

A review with 171 references. Hydrogen-bond acidic polymers for chemical vapor sensors are comprehensively reviewed and selected examples of their use in sensing applications are highlighted.
Spectroscopic analysis of local structure and small particles of catalysts

Abstract Most practical catalysts are highly porous and amorphous. In order to characterize them structurally, it is essential to use spectroscopies dependent on penetrating radiation that do not require long range order. It is also very useful if such spectroscopies are element specific so that the local structure around individual elements might be probed. Extended X-ray absorption fine structure (EXAFS) analysis, NMR and Mossbauer spectroscopies meet these requirements. Each spectroscopy is briefly reviewed and examples of applications of two or more of these spectroscopies to several catalytic investigations are presented. The application of EXAFS and NMR to Pt/Al 2 O 3 , EXAFS and Mossbauer to Pt-Ir/Al 2 2O 3 and Co-Mo/Al 2 O 3 , and EXAFS and NMR to Ni-Mo/Al 2 O 3 catalysts are discussed.
Direct Asymmetric Aldol Reactions of Acetone Using Bimetallic Zinc Catalysts

[reaction: see text] The enantioselective aldol reaction using a novel binuclear zinc catalyst of acetone with several aldehydes gave products in good yields (62-89%) with a high level of enantioselectivity (ee = 76-92%).
THE RESISTIVITY OF LANTHANUM, CERIUM, PRASEODYMIUM AND NEODYMIUM AT LOW TEMPERATURES

The electrical resistivity of lanthanum, cerium, praseodymium, and neodymium metals from room temperature to 2.2\ifmmode^\circ\else\textdegree\fi{}K is presented. The h.c.p. modification of lanthanum is found to possess a higher resistivity than the f.c.c. The mean of the observed superconducting transition temperatures for lanthanum is 5.8\ifmmode^\circ\else\textdegree\fi{}K. Anomalies in the resistivity of cerium which occur at liquid nitrogen temperatures and between 11 and 14\ifmmode^\circ\else\textdegree\fi{} K are discussed in connection with the crystal structure. An anomaly in the resistivity of neodymium occurs at approximately 12\ifmmode^\circ\else\textdegree\fi{}K.
Ensuring correctness at the application level: a software framework approach

As scientific applications extend to the simulation of more and more complex systems, they involve an increasing number of abstraction levels, at each of which errors can emerge and across which they can propagate; tools for correctness evaluation and enforcement at every level (from the code level to the application level) are therefore necessary. Whilst code-level debugging tools are already a well established standard, application-level tools are lagging behind, possibly due to their stronger dependence on the application's details. In this paper, we describe the programming model introduced by the Cactus framework, review the High Performance Computing (HPC) challenges that Cactus is designed to address, and illustrate the correctness strategies that are currently available in Cactus at the code, component, and application level.
Synthesis of 6H-dibenzo[b,d]pyran-6-ones via dienone-phenol rearrangements of spiro[2,5-cyclohexadiene-1,1′(3′H)-isobenzofuran]-3′-ones

Abstract A series of spiro[2,5-cyclohexadiene-1,1′(3′ H )-isobenzofuran]-3′-ones were prepared from metalled benzamides and 4,4-dimethoxycyclohexadienone. Rearrangement of these spirodienones under a variety of conditions gave substituted 6 H -dibenzo[ b,d ]pyran-6-ones. Rearrangements in aqueous sulfuric acid gave products of formal O-migration while rearrangements in trifluoroacetic anhydride-trifluoroacetic acid-sulfuric acid usually gave C-mitration products.
Separated-flow considerations for pressure-atomized combusting monopropellant sprays

The drop and spray combustion properties of the hydroxyl-ammonium nitrate (HAN)-based monopropellant LGP 1845 were studied. Drop-burning rates were measured with drops supported in a combustion gas environment at pressures of 0.2-7.0 MPa. Some internal gasification of drops—causing swelling, partial bursting, and microexplosions—was observed throughout this region, but these disturbances decreased with increasing pressure. Effective drop-burning rates (including effects of both surface gasification and bursting) were relatively constant, ca. 10 mm/s, and were consistent with earlier strand-burning-rate measurements of gelled propellant. Pressure-atomized combusting sprays were studied in combustion gas environments at pressures of 3-9 MPa. The liquid-containing region was significantly larger than earlier measurements of Birk and Reeves,19 as well as predictions based on the locally-homogeneous-flow approximation of multiphase flow theory. In conjunction with drop-trajectory calculations, based on present measurements of drop-burning rates, these findings suggest significant effects of separated flow in combusting HAN-based monopropellant sprays.
Planar Shielded-Loop Resonators

The design and analysis of planar shielded-loop resonators for use in wireless nonradiative power transfer systems is presented. The difficulties associated with coaxial shielded-loop resonators for wireless power transfer are discussed and planar alternatives are proposed. The currents along these planar structures are analyzed and first-order design equations are presented in the form of a circuit model. In addition, the planar structures are simulated and fabricated. Planar shielded-loop resonators are compact and simple to fabricate. Moreover, they are well-suited for printed circuit board designs or integrated circuits.
Relation between time spent outdoors and exfoliation glaucoma or exfoliation glaucoma suspect

Purpose To evaluate the relation between time spent outdoors at various life periods and risk of exfoliation glaucoma or exfoliation glaucoma suspect. Design Retrospective cohort study in the United States. Methods Participants (49 033 women in the Nurses Health Study and 20 066 men in the Health Professionals Follow-up Study) were 60+ years old, were free of glaucoma and cataract, reported eye examinations, and completed questions about time spent outdoors in direct sunlight at midday at 3 life periods: high school to age 24 years, age 25–35 years, and age 36–59 years (asked in 2006 in women and 2008 in men). Participants were followed biennially with mailed questionnaires from 1980 women/1986 men to 2010. Incident cases (223 women and 38 men) were confirmed with medical records. Cohort-specific multivariable-adjusted rate ratios from Cox proportional hazards models were estimated and pooled with meta-analysis. Results Although no association was observed with greater time spent outdoors in the ages of 25–35 or ages 36–59 years, the pooled multivariable-adjusted rate ratios for ≥11 hours per week spent outdoors in high school to age 24 years compared with ≤5 hours per week was 2.00 (95% confidence interval = 1.30, 3.08; P for linear trend = .001). In women, this association was stronger in those who resided in the southern geographic tier in young adulthood ( P for interaction = .07). Conclusions Greater time spent outdoors in young adulthood was associated with risk of exfoliation glaucoma or exfoliation glaucoma suspect, supporting an etiologic role of early exposures to climatic factors.
High-tech capital formation and economic performance in U.S. manufacturing industries An exploratory analysis

Abstract To what extent have investments in ‘high-tech’ office and information technology capital ‘delivered’ in terms of reducing costs and facilitating productivity growth? In this paper we explore relationships between industry performance measures and investments in high-tech office and information technology capital for two-digit manufacturing industries from 1968 through 1986. We find limited evidence of a positive relationship between profitability and the share of high-tech capital in the total physical capital stock ( OF K ). However, we find that increases in OF K are negatively correlated with multi-factor productivity and tend to be labor-using. We also find some evidence that industries with a higher proportion of high-tech capital have higher measures of economic performance, although within industries increasing OF K does not appear to improve economic performance.
Infrared matrix-isolation spectra of monomeric oxalic acid

Abstract Infrared spectra of monomeric oxalic acid-h2, -hd and -d2 have been observed using neon matrix-isolation spectroscopy. In addition, spectra of oxalic acid-h2, vapor were obtained using a heated absorption cell with a 10 m pathlength. All IR active fundamentals are assigned for oxalic acid-h2, and -d2, except the low frequency torsion. The spectra are interpreted in terms of the C2h intramolecularly hydrogen bonded model. Two vibrational assignments are discussed; one involves a very large intensity for the v8 + v11 (COH torsion) combination band of oxalic acid-h2. Tentative values for several Raman active fundamentals of oxalic acid-h2 are suggested using possible combination bands. Few fundamentals of oxalic acid-hd correlating with the Raman modes of the symmetric monomers could be observed. A force constant analysis of the by secular block is presented.
The life cycle of scholars and papers in economics – the ‘citation death tax’

The information content of academic citations is a subject to debate. This article views premature death as a tragic ‘natural experiment’, outlining a methodology identifying the ‘citation death tax’ – the impact of the death of productive economists on the patterns of their citations. We rely on a sample of 428 papers written by 16 well-known economists who died well before retirement, during the period 1975 to 1997. The news is mixed: for half of the sample, we identify a large and significant ‘citation death tax’ for the average paper written by these scholars. For these authors, the estimated average missing citations per paper attributed to premature death ranges from 40% to 140% (the overall average is about 90%), and the annual costs of lost citations per paper are in the range 3–14%. Hence, a paper written 10 years before the author's death avoids a citation cost that varies between 30% and 140%. For the other half of the sample, there is no citation death tax; and for two Nobel Prize-calibre scho...
New cytotoxic sesquiterpenoid nitrobenzoyl esters from a marine isolate of the fungus Aspergillus versicolor

Abstract Four new sesquiterpenoid nitrobenzoyl esters (1–4) have been isolated from organic extracts of the culture broth and mycelia of Aspergillus versicolor, a fungus isolated from the surface of the Caribbean green alga Penicillus capitatus. The structures of the four compounds were determined through extensive analysis of 1H NMR, 13C NMR, HMQC, and HMBC data. 9α, 14-Dihydroxy-6β-p-nitrobenzoylcinnamolide (1) displayed significant cytotoxicity against HCT-116 human colon carcinoma cells in vitro and exhibited moderately selective cytotoxicity toward a panel of renal tumor cell lines.
An excessive development of green products

This paper examines firms’ incentives to develop a new (green) product, which might compete against the pollutant (brown) good that they traditionally sell. We show that in equilibrium more than one firm might develop a green product, but such an equilibrium outcome is not necessarily efficient. In particular, we predict an excessive amount of green goods under certain conditions, namely, when the green product is extremely clean but both products are not sufficiently differentiated in their attributes, and when the green product is not significantly cleaner than the brown good. We finally provide policies that help regulatory authorities promote equilibrium outcomes yielding the highest social welfare.
Degenerations of surface scrolls and the Gromov-Witten invariants of Grassmannians

We describe an algorithm for computing certain characteristic numbers of rational normal surface scrolls using degenerations. As a corollary we obtain an efficient method for computing the corresponding Gromov-Witten invariants of the Grassmannians of lines.
Qualitative rigid-body mechanics

Abstract We present a theory of qualitative rigid-body mechanics and describe a program that uses this theory to compute qualitative rigid-body dynamic simulations. The program works directly from a qualitative representation of geometry—qualitative configuration space—without need of any metric information. The program can handle devices that are composed of an arbitrary number of fixed-axis components and springs, with driving inputs coming from both applied motions and forces. The program employs quasi-static assumptions, i.e., inertia-free motion, inelastic collisions, and frictionless contacts. It employs a new qualitative representation for forces that reduces ambiguity in force sums and hence reduces unnecessary branching.
A Statistical Treatment of the Gamma-Ray Burst “No Host Galaxy” Problem. I. Methodology

If gamma-ray bursts originate in galaxies at cosmological distances, the host galaxy should be detected if a burst error box is searched deeply enough; are the host galaxies present? We present and implement a statistical methodology that evaluates whether the observed galaxy detections in a burst's error box are consistent with the presence of the host galaxy, or whether all the detections can be attributed to unrelated background galaxies. This methodology requires the model-dependent distribution of host-galaxy fluxes. While our methodology was derived for galaxies in burst error boxes, it can be applied to other candidate host objects (e.g., active galaxies) and to other types of error boxes. As examples, we apply this methodology to two published studies of burst error boxes. We find that the nine error boxes observed by Larson and McLean are too large to discriminate between the presence or absence of host galaxies, while the absence of bright galaxies in the four significantly smaller error boxes observed by the Hubble Space Telescope (Schaefer et al.) does confirm that there is a "no host galaxy" problem within the "minimal" host-galaxy model.
Preparation and characterization of nanocrystalline composite (nanocomposite) films of titanium dioxide and nickel by occlusion electrodeposition

A new family of nanocrystalline composite films was developed for photoelectrochemical application by occlusion deposition of TiO2 particles from a nickel plating bath. The photoactivity of the resultant Ni¦TiO2 films was examined under chopped-light illumination with a xenon arc lamp in 0.1 M KNO3. A TiO2 dose in the nickel bath of 0.8 M, a deposition potential of −0.8 V, a bath pH of 5.0, a bath temperature of 20°C and a film deposition charge of 36 mC (corresponding to a film ca. 0.7 μm thick) were found to yield the best photoresponse for the resultant Ni¦TiO2 films. The photoresponse of these nanocomposite films was compared with that of TiO2 layers on Ti supports, obtained either from thermal oxidation of titanium or by oxidative decomposition of aq. TiCl4 at 550°C. Formate and acetate ions were employed as current-doubling agents in the 0.1 M KNO3 electrolyte for this comparative study. The current-doubling effect was seen to be the highest for the Ni¦TiO2 films; possible mechanistic origins for this trend are discussed. Other characterizations of the Ni¦TiO2 films, including analyses by laser Raman spectroscopy,and X-ray photoelectron spectroscopy, are also discussed.
Signatures of Planet Formation in Gravitationally Unstable Disks

In this Letter, we calculate simulated scattered light images of a circumstellar disk in which a planet is forming by gravitational instability. The simulated images bear no correlation to the vertically integrated surface density of the disk, but rather trace the density structure in the tenuous upper layers of the disk. Although the density at high altitudes does not bear a direct relation to activity at the midplane, the very existence of structure at high altitudes along with high time variability is an indicator of gravitational instability within the disk. The timescale for variations is much shorter than the orbital period of the planet, which facilitates observation of the phenomenon. Scattered light images may not necessarily be able to tell us where exactly a planet might be forming in a disk but can still be a useful probe of active planet formation within a circumstellar disk. Although these phenomena are unlikely to be observable by current telescopes, future large telescopes, such as the Giant Magellan Telescope, may be able to detect them.
108 Gb/s OFDMA-PON With Polarization Multiplexing and Direct Detection

In this paper, we propose and experimentally demonstrate the first single-? 40 Gb/s and 108 Gb/s multiple-input multiple-output orthogonal frequency-division multiple access (OFDMA) passive optical networks (PON) architecture for next-generation PON systems based on OFDM, polarization multiplexing (POLMUX), and direct detection. Superior performance was exhibited after 20 km SSMF transmission and a 1:32 optical split. The novel POLMUX approach greatly simplified receiver-end hardware compared to coherent detectors, while increasing spectral efficiency to enable 40+ Gb/s data rates. Moreover, the proposed solution achieved the highest single-wavelength downstream transmission reported to date in any PON system. As such, the introduced architecture may be viewed as a highly attractive candidate for next-generation optical access.
Concentration and convergence rates for spectral measures of random matrices

The topic of this paper is the typical behavior of the spectral measures of large random matrices drawn from several ensembles of interest, including in particular matrices drawn from Haar measure on the classical Lie groups, random compressions of random Hermitian matrices, and the so-called random sum of two independent random matrices. In each case, we estimate the expected Wasserstein distance from the empirical spectral measure to a deterministic reference measure, and prove a concentration result for that distance. As a consequence we obtain almost sure convergence of the empirical spectral measures in all cases.
Hindman's Theorem: An Ultrafilter Argument in Second Order Arithmetic

Hindman's Theorem is a prototypical example of a combinatorial theorem with a proof that uses the topology of the ultrafilters. We show how the methods of this proof, including topological arguments about ultrafilters, can be translated into second order arithmetic.