cssi/SciSciGPT-SciSciNet huggingface dataset:
Wave Number Frequency Spectra of a Lifting Wake for Broadband Noise Prediction

Measurements of wave number frequency spectra of velocity fluctuations have been made using two three-component hot-wire probes in the wake of a rectangular NACA 0012 half-wing at a 5-deg angle of attack. Spectra were measured along spanwise lines in the near two-dimensional part of the wake, in the stretched region where the wake begins to wind around the vortex, directly above the vortex core, and radially from the core center. Dominated by the large-scale organized motions present in the wake, the spectra show little similarity with the von Karman isotropic turbulence spectrum. Outside the core, upwash spectra contain a single maximum at the passage frequency of these large structures. Motions associated with this peak are highly anisotropic, both in terms of velocity components and length scales. Similar anisotropy is also seen at higher wave numbers, suggesting either that the smaller scale turbulent motions are organized by the large eddies or that the nonsinusoidal components of those eddies contribute significantly to the spectrum at higher wave numbers. The implications of these results for broadband noise prediction have been assessed by considering the sound radiation from this turbulent flow over a semi-infinite flat plate. The major conclusion is that the correlation length scales of the flow are small compared to the acoustic wavelength and so are well represented by their values at zero spanwise wave number. However, the blade response function has a variation with spanwise wave number that cannot be ignored and significantly influences the spanwise directionality.
Antineutrino geophysics with liquid scintillator detectors

Detecting the antineutrinos emitted by the decay of radioactive elements in the mantle and crust could provide a direct measurement of the total abundance of uranium and thorium in the Earth. In calculating the antineutrino flux at specific sites, the local geology of the crust and the background from the world's nuclear power reactors are important considerations. Employing a global crustal map, with type and thickness data, and using recent estimates of the uranium and thorium distribution in the Earth, we calculate the antineutrino event rate for two new neutrino detectors. We show that spectral features allow terrestrial antineutrino events to be identified above reactor antineutrino backgrounds and that the uranium and thorium contributions can be separately determined.
Ceria in catalysis: From automotive applications to the water–gas shift reaction

Ceria is a crucial component of automotive catalysts, where its ability to be reduced and re-oxidized provides oxygen storage capacity. Because of these redox properties, ceria can greatly enhance catalytic activities for a number of important reactions when it is used as a support for transition metals. For reactions that use steam as an oxidant (e.g., the water–gas-shift reaction and steam reforming of hydrocarbons), rates for ceria-supported metals can be several orders of magnitude higher than that for ceria or the transition metal alone. Because the redox properties of ceria are strongly dependent on treatment history and the presence of additives, there are significant opportunities for modifying catalysts based on ceria to further improve their performance. This article will review some of the contributions from my laboratory on understanding and using ceria in these applications. © 2010 American Institute of Chemical Engineers AIChE J, 2010
Combinatorial libraries of transition-metal complexes, catalysts and materials

The design, synthesis and evaluation of transition metal containing combinatorial libraries has received much attention in the past few years. As a result, a variety of synthetic techniques have been developed, and rapid assays for metal ion binding have yielded new ligand classes displaying high affinity and selectivity. Research in catalysis has centered around lead optimization using much smaller parallel libraries because of the lack of a truly efficient reaction screening method. Materials science applications have also focused on spatially addressed libraries and have employed a variety of techniques to identify compounds with desired physical properties. Nonetheless, high-throughput characterization and reaction product detection methods must still be developed in order to realize the full potential of combinatorial chemistry for the discovery of novel metal-containing compounds.
Higgs mass from D-terms: a litmus test

We explore supersymmetric theories in which the Higgs mass is boosted by the non-decoupling D-terms of an extended U(1) X gauge symmetry, defined here to be a general linear combination of hypercharge, baryon number, and lepton number. Crucially, the gauge coupling, g X , is bounded from below to accommodate the Higgs mass, while the quarks and leptons are required by gauge invariance to carry non-zero charge under U(1) X . This induces an irreducible rate, σBR, for pp → X → ll relevant to existing and future resonance searches, and gives rise to higher dimension operators that are stringently constrained by precision electroweak measurements. Combined, these bounds define a maximally allowed region in the space of observables, (σBR, m X ), outside of which is excluded by naturalness and experimental limits. If natural supersymmetry utilizes non-decoupling D-terms, then the associated X boson can only be observed within this window, providing a model independent ‘litmus test’ for this broad class of scenarios at the LHC. Comparing limits, we find that current LHC results only exclude regions in parameter space which were already disfavored by precision electroweak data.
TW HYA Association Membership and New WISE-detected Circumstellar Disks

We assess the current membership of the nearby, young TW Hydrae association and examine newly proposed members with the Wide-field Infrared Survey Explorer (WISE) to search for infrared excess indicative of circumstellar disks. Newly proposed members TWA 30A, TWA 30B, TWA 31, and TWA 32 all show excess emission at 12 and 22 μm providing clear evidence for substantial dusty circumstellar disks around these low-mass, ~8 Myr old stars that were previously shown to likely be accreting circumstellar material. TWA 30B shows large amounts of self-extinction, likely due to an edge-on disk geometry. We also confirm previously reported circumstellar disks with WISE and determine a 22 μm excess fraction of 42+10 – 9% based on our results.
Motorcyclist fatalities and the repeal of mandatory helmet wearing laws

Previous studies had estimated that repeal of mandatory helmet wearing laws resulted in increases in the number of fatalities ranging from nearly 40% to essentially zero. This study was performed to determine more definitively the influence on motorcyclist fatalities of these repeals. After repeal, motorcyclist fatalities increased more in the states which repealed their laws than in those which did not in 24 cases out of 26, with the 95% confidence interval for the average effect being 25 +/- 6%. It is therefore concluded that repeals of mandatory helmet wearing laws for motorcyclists were followed by substantial increases in motorcyclist fatalities.
New supersymmetric electroweak gauge model with natural baryon-number conservation

Abstract Baryon number ( B ) is automatically conserved in the standard SU(2) × U(1) electroweak gauge model, but not in its supersymmetric extension where it must be imposed as an extra condition. This undesirable feature is avoided in the conventional left-right supersymmetric extension, but then flavor-changing neutral currents (FCNC) are not naturally suppressed. A new version is proposed with automatic B conservation as well as FCNC suppression except for u quarks through scalar exchange which then makes possible the decay t → c + Higgs boson.
Characterization of Sol‐Gel‐Derived Cobalt Oxide Xerogels as Electrochemical Capacitors

Very fine cobalt oxide xerogel powders were prepared using a unique solution chemistry associated with the sol-gel process. The effect of thermal treatment on the surrace area, pore volume, crystallinity, particle structure, and corresponding electrochemical properties of the resulting xerogels was investigated and found to have significant effects on all of these properties. The xerogel remained amorphous as Co(OH) 2 up to 160°C, and exhibited maxima in both the surface area and pore volume at this temperature. With an increase in the temperature above 200°C, both the surface area and pore volume decreased sharply, because the amorphous Co(OH) 2 decomposed to form CoO that was subsequently oxidized to form crystalline Co 3 O 4 In addition, the changes in the surface area, pore volume, crystallinity, and particle structure all had significant but coupled effects on the electrochemical properties of the xerogels. A maximum capacitance of 291 F/g was obtained for an electrode prepared with the CoO x xerogel calcined at 150°C, which was consistent with the maxima exhibited in both the surface area and pore volume; this capacitance was attributed solely to a surface redox mechanism. The cycle life of this electrode was also very stable for many thousands of cycles
Balancing order and chaos in image generation

Abstract We introduce new techniques to generate real-world images. Many of the natural images exhibit a hierarchical structure and a balanced combination of both order and chaos. We show how a controlled use of deterministic chaos yields a powerful method to concisely describe and to efficiently generate complex realistic images. The basic technique is the use of Mutually Recursive Function Systems (MRFS) possibly with additional control on the order of computations. Then we show that, surprisingly, regular sets of control sequences are convenient but not essential. Some examples are presented illustrating the power of the technique.
Synthesis and reactions of achiral 3-substituted vinylketene acetals as dienes in the Diels-Alder reaction

Abstract The synthesis of three new vinylketene acetals, each bearing a heteroatom substituent at C3 of the diene unit, and their reactions with representative dienophiles in Diels-Alder reactions are presented. All the dienes react well at room temperature, indicating substantial activation of the cycloaddition event. The stereochemistry of the major Diels-Alder product of a 3-SPh-substituted vinylketene acetal is opposite to that produced by the corresponding 3-unsubstituted compound.
LISA optics model: early results

This note presents some of the optical modeling work performed at JPL and at Goddard in support of the Laser Interferometer Space Antenna (LISA) effort. The end-to-end optical model will be used to generate a synthetic data stream. The simulation will have the spacecraft moving in their respective orbits, with pointing of the spacecraft and station keeping about the proof masses accomplished using a control scheme, which minimizes the disturbance on the proof masses in the sensitive direction. The resulting data stream gives an indication of the magnitude of instrumental noise due to pointing jitter and motions of the spacecraft with respect to the proof masses. To reach this goal portions of the overall optical train have been modeled. Subsequent work will, as the modeling software and optical model evolve, combine these pieces into an integrated system.
Preparation of Calcium Lanthanum Sulfide Powders via Alkoxide Sulfurization

This paper reports that calcium lanthanum sulfide powders are prepared by reacting methoxides of calcium and lanthanum with H[sub 2]S. Alkoxide mixtures of various La/Ca ratios dispersed in methanol were reacted with H[sub 2]S at 25[degrees] to 85[degrees] C and the amorphous gels obtained after the removal of methanol were heat-treated in H[sub 2]S for full sulfurization at various temperatures. Up to 500[degrees] C, cubic LaS[sub 2] was the only crystalline phase present. Calcium lanthanum sulfide phase started to form at 550[degrees] C. In the temperature range of 650[degrees] to 750[degrees] C, single-phase calcium lanthanum sulfide powders were obtained for La/Ca = 2.41 and 2.68.
A Highly Efficient Palladium/Copper Cocatalytic System for Direct Arylation of Heteroarenes: An Unexpected Effect of Cu(Xantphos)I

Heteroarenes are important structural moieties in many chemical industry fields. A highly efficient Pd/Cu-catalyzed C−H arylation method for a range of heterocycles has been discovered. It was found that the key to the success of this transformation is a combination of a palladium catalyst and a well-defined copper cocatalyst. The efficiency and low loadings of catalyst (0.25 mol %) and cocatalyst (1 mol %) together with the mild reaction conditions demonstrate this method to be practically useful and mechanistically interesting.
Connecting Blackbody Radiation, Relativity, and Discrete Charge in Classical Electrodynamics

It is suggested that an understanding of blackbody radiation within classical physics requires the presence of classical electromagnetic zero-point radiation, the restriction to relativistic (Coulomb) scattering systems, and the use of discrete charge. The contrasting scaling properties of nonrelativistic classical mechanics and classical electrodynamics are noted, and it is emphasized that the solutions of classical electrodynamics found in nature involve constants which connect together the scales of length, time, and energy. Indeed, there are analogies between the electrostatic forces for groups of particles of discrete charge and the van der Waals forces in equilibrium thermal radiation. The differing Lorentz- or Galilean-transformation properties of the zero-point radiation spectrum and the Rayleigh-Jeans spectrum are noted in connection with their scaling properties. Also, the thermal effects of acceleration within classical electromagnetism are related to the existence of thermal equilibrium within a gravitational field. The unique scaling and phase-space properties of a discrete charge in the Coulomb potential suggest the possibility of an equilibrium between the zero-point radiation spectrum and matter which is universal (independent of the particle mass), and an equilibrium between a universal thermal radiation spectrum and matter where the matter phase space depends only upon the ratio mc 2/k B T. The observations and qualitative suggestions made here run counter to the ideas of currently accepted quantum physics.
Real-time control of the periodicity of a standing wave: an optical accordion.

We report an experimental method to create optical lattices with real-time control of their periodicity. We demonstrate a continuous change of the lattice periodicity from 0.96 µm to 11.2 µm in one second, while the center fringe only moves less than 2.7 µm during the whole process. This provides a powerful tool for controlling ultracold atoms in optical lattices, where small spacing is essential for quantum tunneling, and large spacing enables single-site manipulation and spatially resolved detection.
Very Large Array Observations of Galactic Center OH 1720 MHz Masers in Sagittarius A East and in the Circumnuclear Disk

We present Very Large Array (VLA) radio interferometry observations of the 1720 MHz OH masers in the Galactic center (GC). Most 1720 MHz OH masers arise in regions where the supernova remnant Sgr A East is interacting with the interstellar medium. The majority of the newly found 1720 MHz OH masers are located to the northeast, independently indicating and confirming an area of shock interaction with the +50 km s−1 molecular cloud (M–0.02–0.07) on the far side of Sgr A East. The previously known bright masers in the southeast are suggested to be the result of the interaction between two supernova remnants, instead of between Sgr A East and the surrounding molecular clouds, as generally found elsewhere in the Galaxy. Together with masers north of the circumnuclear disk (CND) they outline an interaction on the near side of Sgr A East. In contrast to the interaction between the +50 km s−1 cloud and Sgr A East, OH absorption data do not support a direct interaction between the CND material and Sgr A East. We also present three new high-negative velocity masers, supporting a previous single detection. The location and velocities of the high-negative and high-positive velocity masers are consistent with being near the tangent points of, and physically located in, the CND. We argue that the high-velocity masers in the CND are pumped by dissipation between density clumps in the CND instead of a shock generated by the supernova remnant. That is, the CND masers are not coupled to the supernova remnant and are sustained independently.
Design of drugs involving the concepts and theories of drug metabolism and pharmacokinetics

Drug metabolism input to the discovery process had historically been on an empirical case-by-case basis, since, detailed descriptors of the effect on pharmacokinetics of a change in structure or physicochemical property were not available. Considerable advances have been made in recent years, such that basic rules can be applied to predict the behavior of a compound in man based on physicochemistry and structure. This is particularly true in the areas of absorption, distribution, and clearance. In particular, knowledge of the reactions catalyzed by the enzymes of drug metabolism, including the cytochrome P450 super family, can be used in the design of new chemical entities, together with the usual pharmacological-derived SAR. The combination of both pharmacokinetics and pharmacodynamics at the discovery stage leads to drugs with optimum performance characteristics. Such drugs are easier to develop, representing a huge saving in resources. Moreover, the marketed compound is much more likely to find high clinical utilization. This review uses dofetilide, fluconazole, and amlodipine to highlight the multifaceted consequences of changing chemical structure, in terms of drug disposition, and reinforces these principles with examples from the literature.
On the random oracle hypothesis

Two counterexamples to the random oracle hypothesis as formalized by Bennett and Gill (1975, SIAM J. Comput. 10 , 96–113), are given. Then the future of the random oracle hypothesis in light of these examples is discussed. It is believed that these examples will severely test any new candidate for a formal random oracle hypothesis.
Organocatalyzed enantioselective aldol reaction of 1H-pyrrole-2,3-diones.

Abstract The enantioselective cross aldol reaction of 1-benzyl 4,5-dioxo-2-aryl-4,5-dihydro-1H-pyrrole-3-carboxylates and ketones was studied with proline derivatives or cinchona alkaloid-derived primary amines as the catalysts for the first time. trans-4-Benzoyloxy- l -proline (15) was found to be the best catalyst for acyclic ketones. For cyclohexanone, the best results were achieved with 9-deoxy-9-epi-aminoquinine (18) as the catalyst in the presence of racemic 1,1′-binaphthyl-2,2′-diyl hydrogen phosphate (19) as the cocatalyst. Using these protocols, 3-alkyl-3-hydroxy-1H-pyrrol-2(3H)-one derivatives were obtained in excellent yields and good to high ee values (up to 94% ee).
Clinical and roentgenographic evaluation of endoscopic suspension of the vesical neck for urinary incontinence

Forty-four consecutive patients, without residual urine or infecttion, were operated upon for urinary stress incontinence by endoscopie suspension of the vesical neck. All patients had preoperative and post-operative lateral view cystograms which showed after operation substantial upward and forward elevation of the urethrovesical junction as measured by the posterior urethrovesical angle, the angle of urethral inclination, and elevation of the base of bladder. Despite a significant history of an urgency component to their incontinence in many patients, as well as 44 previous operations in 22 of the patients, a carefully performed cystometrogram and cholinergic sensitivity test were not helpful in detecting abnormalities of the detrusor muscle. Fourty-one patients were cured, and in three others, the condition was not cured, the failure group. The lateral view cystogram was the most diagnostic test in that two in the failure group did not show preoperatively the roentgenographic hallmark of stress urinary incontinence.
Carbaporphyrinoid chemistry has a silver lining! silver(III) oxybenzi-, oxynaphthi-, tropi-, and benzocarbaporphyrins.

Carbaporphyrinoid systems with semiquinone, cycloheptatriene, or indene subunits react under mild conditions with silver(I) acetate to give stable silver(III) organometallic derivatives.
Triple energy window scatter correction technique in PET

A practical triple energy window technique (TEW) is proposed, which is based on using the information in two lower energy windows and one single calibration, to estimate the scatter within the photopeak window. The technique is basically a conventional dual-window technique plus a modification factor, which can partially compensate object-distribution dependent scatters. The modification factor is a function of two lower scatter windows of both the calibration phantom and the actual object. In order to evaluate the technique, a Monte Carlo simulation program, which simulates the PENN-PET scanner geometry, was used. Different phantom activity distributions and phantom sizes were tested to simulate brain studies, including uniform and nonuniform distributions. The results indicate that the TEW technique works well for a wide range of activity distributions and object sizes. The comparisons between the TEW and dual window techniques show better quantitative accuracy for the TEW, especially for different phantom sizes. The technique is also applied to experimental data from a PENN-PET scanner to test its practicality. >
Concave accretion discs and X‐ray reprocessing

Spectra of Seyfert 1s are commonly modelled as emission from an X-ray-illuminated flat accretion disc orbiting a central black hole. This provides both reprocessed and direct components of the X-ray emission, as required by observations of individual objects, and possibly a fraction of the cosmological X-ray background. There is some observational motivation for us to at least consider the role that an effectively concave disc surface might play: (1) a reprocessed fraction ≳1/2 in some Seyferts and possibly in the X-ray background, and (2) the commonality of a sharp iron line peak for Seyferts at 6.4 keV despite a dependence of peak location on inclination angle for flat disc models. Here it is shown that a concave disc may not only provide a larger total fraction of reprocessed photons, but can also reprocess a much larger fraction of photons in its outer regions compared with a flat disc. This reduces the sensitivity of the 6.4-keV peak location to the inner disc inclination angle because the outer regions are less affected by Doppler and gravitational effects. If the X-ray source is isotropic, the reprocessed fraction is directly determined by the concavity. If the X-ray source is anisotropic, the location of iron line peak can still be determined by concavity but the total reflected fraction need not be as large as for the isotropic emitter case. The geometric calculations herein are applicable to general accretion disc systems illuminated from the centre.
Optical Aharonov-Bohm Effect: An Inverse Hyperbolic Problems Approach

We describe the general setting for the optical Aharonov-Bohm effect based on the inverse problem of the identification of the coefficients of the governing hyperbolic equation by the boundary measurements. We interpret the inverse problem result as a possibility in principle to detect the optical Aharonov-Bohm effect by the boundary measurements.
Radioactive beam studies of cosmological interest

Abstract Experimental efforts by the LLNL/Ohio State radioactive ion beam collaboration are described. We are presently focusing on some reactions which are of great importance in the newly proposed inhomogeneous big bang cosmological models [G.M. Fuller, G.J. Mathews and C.R. Alcock, in: Origin and Distribution of the Elements, ed. G.J. Mathews (World Scientific, Singapore, 1987)]. Specifically we are using our system to make beams of 8 Li for measurements of the 8 Li(d, n) 9 Be and 8 Li(a, n) 11 B cross sections. These are the key reactions which determine the production of heavy ( A > 12) elements during the era of big bang nucleosynthesis, and thus the initial composition of stars and subsequent stellar isotope production. Plans for future experiments, including the measurement of the 7 Be(p, γ) 8 B cross section will be discussed.
Hydroxyurea and macrocytosis.

SUMMARY Nine patients who were treated for psoriasis with hydroxyurea displayed peripheral macrocytosis. Mild megaloblastic changes were also seen in the bone marrow of three patients. One patient receiving hydroxyurea developed mild anaemia, another leukopenia. Macrocytosis did not appear to be secondary to an alteration in serum B12 or folate levels. The haematological side-effects of hydroxyurea therapy, at the relatively low doses used to treat psoriasis, are similar to those seen with the higher doses used for the treatment of malignant tumours or leukaemia.
The relation of QT dispersion to spontaneous ventricular arrhythmias during the acute phase of myocardial infarction

Background: QT dispersion is associated with ventricular arrhythmias and sudden death among patients with a previous myocardial infarction (Ml). The relationship between QT dispersion and ventricular arrhythmias during the acute phase of Ml is uncertain. Methods: Patients enrolled in the Multicenter Study of Silent Myocardial Ischemia who had first Q wave myocardial infarctions (n = 363) were screened for the presence of ventricular arrhythmias during the initial hospitalization. Twelve patients had ventricular fibrillation, and 18 patients had an episode of monomorphic ventricular tachycardia. Each patient who had ventricular arrhythmias was matched with four controls on the basis of age, peak creatine kinase, thrombolysis, and the presence of congestive heart failure. The final study population consisted of 150 patients: 12 patients with ventricular fibrillation (VF+) who were compared to 48 controls (VF—), and 18 patients with ventricular tachycardia (VT+) who were compared to 72 controls (VT–). The RR, QRS, and QT intervals were measured manually using standard 12-lead ECGs (25 mm/s) obtained after hospital admission. The maximal QT dispersion (maximum — minimum value) was calculated. Multivariate logistic regression analysis was performed to determine if QT dispersion was independently associated with ventricular arrhythmias during the acute phase of Ml. Results: QT dispersion was significantly greater in VF+ patients compared to VF— patients (89 ± 18 ms vs 66 ± 22 ms, P > 0.01). QT dispersion was similar in VT+ and VT— patients (68 ± 25 ms vs 68 ± 26 ms, P = NS). QT dispersion was the only variable that was independently associated with ventricular fibrillation (OR 1.7 for each 10-ms increment in QT dispersion; 95% Cl 1.2–2.6; P = 0.008). QT dispersion was not associated with monomorphic ventricular tachycardia (OR 1.0; 95% Cl 0.8–1.2; P = NS). Conclusion: QT dispersion is independently associated with ventricular fibrillation, but not monomorphic ventricular tachycardia, during the acute phase of Ml.
Temperature dependence of the ordering of semiconducting fluorene-thiophene copolymers on rubbed polyimide alignment layers

There has been great interest in recent years in using solution processible conjugated organic polymers as the active layers in semiconducting devices including field-effect transistors (FETs), light emitting diodes (LEDs), and photovoltaics (PVs). The structure of the polymer film is very important to device performance at the interfaces where charge separation and collection occur, as well as in the bulk of the film, where it has been shown that alignment of the polymer backbone can increase the pi-orbital overlap, thus enhancing charge carrier mobility. In this work, we report on the temperature-dependent alignment of liquid crystalline fluorene-thiophene copolymer thin film surfaces using the near-edge X-ray fine absorption structure (NEXAFS) technique. Partial electron yield spectra were recorded over a range of temperatures to observe directly the bond orientation in various polymer phases. In addition, samples were annealed under varying processing conditions and spectra were taken at room temperature on these heat-treated samples. The NEXAFS data shows: a) in thin polyfluorene films, the polymer backbone lies flat in the plane of the substrate, b) that along the main chain axis, biphenyl and thiophene rings have a preference to lie flat in the plane of the surface, c) the orientation of the polymer backbone can be controlled using a rubbed polyimide alignment layer as a template for liquid crystal orientation, and d) under proper annealing conditions, there is strong temperature-dependent alignment of the copolymer main-chain axis to the rubbing direction with dichroic ratio (R) reaching R=0.7.
Solar absorptance of second surface mirrors for high angles of incidence

Test and calculations indicate an increase rather than a decrease in solar absorptance of second surface mirrors at angles of incidence greater than 80/sup 0/. In practical applications, this effect will be insignificant because, although the solar absorptance is high, the projected area is compensatingly small, resulting in an insignificant increase in the solar or albedo load. However, a spin-stabilized spacecraft can expose second surface mirrors to all angles of incidence. Also, reflected solar energy from a planet or other spacecraft surface could impinge predominantly in the region of high angles of incidence. If a large area is involved, the total load could be significant. Also, if the spacecraft trajectory is toward the sun, the additional loading would become progressively larger. Obviously, a concentration of solar energy in this high absorptance region could have a disastrous effect on a thermal design if overlooked.
Measuring Integration and Efficiency in International Agricultural Markets

This paper critiques the methods used to investigate integration and efficiency in international markets. Integration is best reflected by flow-based indicators of tradability, while efficiency is related to price-based notions of market equilibrium. Data insufficiency poses a serious constraint because empirical tests that rely on just prices cannot separate tests of the market efficiency hypothesis from tests of the strong assumptions underpinning model specification. Finally, even if market efficiency holds, there may nonetheless be considerable social inefficiency remaining due to trade barriers and excessive costs of commerce.
Multilateral Contracting and the Employment Relationship

This paper studies the structure of the employment relationship in organizations. It investigates the trade-off firms face between making commitments to their workforce as a whole (multilateral relational contracts), and making more limited commitments to individuals or smaller groups of employees (bilateral relational contracts). Multilateral contracts bind the firm more strongly to implicit commitments, improving motivation, but are difficult to adjust in response to changes in the environment. Bilateral contracts make workforce changes easier to implement. The framework helps to explain the use of relative performance evaluation, why firms rely on temporary employees, and the adoption of two-tier workforces.
Topological gravity on the lattice

In this paper we show that a particular twist of N = 4 super Yang-Mills in three dimensions with gauge group SU(2) possesses a set of classical vacua corresponding to the space of flat connections of the complexified gauge group SL(2;C). The theory also contains a set of topological observables corresponding to Wilson loops wrapping non-trivial cycles of the base manifold. This moduli space and set of topological observables is shared with the Chern Simons formulation of three dimensional gravity and we hence conjecture that the Yang-Mills theory gives an equivalent description of the gravitational theory. Unlike the Chern Simons formulation the twisted Yang-Mills theory possesses a supersymmetric and gauge invariant lattice construction which then provides a possible non-perturbative definition of three dimensional gravity.
Meteor masses and luminosity

Analysis of meteor luminous efficiency based on photographic data, taking into account fragmentation effects
Neutron scattering, magnetometry, and quantum Monte Carlo study of the randomly diluted spin-1/2 square-lattice Heisenberg antiferromagnet

Abstract We have successfully grown sizable single crystals of La 2 Cu 1− z (Zn,Mg) z O 4 with up to nearly half of the magnetic Cu sites replaced by non-magnetic Zn and Mg. Neutron scattering, SQUID magnetometry, and complementary quantum Monte Carlo (QMC) simulations demonstrate that this material is an excellent model system for the study of site percolation of the square-lattice Heisenberg antiferromagnet (SLHAF) in the quantum-spin limit S =1/2. Carefully oxygen-reduced samples exhibit Neel order up to the percolation threshold for site dilution, z p ≈40.7%. For z >10%, the material exhibits a low-temperature tetragonal (LTT) structural phase, with a transition temperature that increases linearly with doping. Above z ≈25%, Neel order occurs in the LTT phase. Up to at least z =35%, the Neel temperature T N ( z ) of the experimental system corresponds to the temperature at which QMC indicates that the spin correlations for the nearest-neighbor S =1/2 SLHAF have grown to approximately 100 lattice constants. Neutron scattering measurements of the static structure factor in the paramagnetic regime allow the determination of the two-dimensional spin correlations, which are found to be in excellent quantitative agreement with QMC over a wide common temperature and doping range. Neutron scattering and QMC results for the temperature dependence of the static structure factor amplitude S (π,π) are in good agreement as well. As the concentration of non-magnetic sites is increased, the magnetic correlation length ξ ( T , z ) crosses over from an exponential dependence on ρ s / T to power-law behavior in the temperature regime studied. Fits to a heuristic cross-over form for ξ ( T , z ) allow an estimate of the spin stiffness, ρ s = ρ s ( z ), which approaches zero at z = z p . The combined experimental and numerical data presented here provide valuable quantitative information for tests of theories of the randomly diluted S =1/2 SLHAF.
Spin correlation in top quark production at hadron colliders

We propose techniques to observe the correlation of the spins of top quarks and antiquarks at the Tevatron and the LHC. Observation of the spin correlation would confirm that the top quark decays before its spin flips, and would place a lower bound on the top-quark width and Vtb. The spin correlation may also be a useful tool to study the weak decay amplitude of the top quark.
Bubble Domain Technology For Spacecraft Onboard Memory

Nonvolatile memory for data and control programs is required for advanced remote sensor systems. Simultaneous storage for data processing and data accumulation will provide versatile sensor control and optimized data link buffering. Bubble domain technology offers significant reliability and functional advantages for meeting these complicated high density memory requirements. Bubble operational capability includes multifunctional block and serial access, first-in/first-out storage, simultaneous read/write, asynchronous data rates, and expandable capacities. Several bubble device technologies have emerged in recent years. Permalloy gap devices are available commercially, while more recent device technologies such as ion implant and self-structured current accessed are in research stages. The newer device concepts are aimed at increasing storage density and data rates while minimizing power and cost. A flexible system concept is analyzed which is compatible with all of these bubble device technologies. Detailed estimates of memory system characteristics are discussed for each type of bubble device. System capacity, weight, and volume tradeoffs are dependent on the basic device data site period and on the device packaging scheme. Data rate and power dissipation are coupled to device technology, data site period, and also the device packaging scheme. Permalloy gap, ion implant, and self-structured current access systems appear to respectively offer capacities of up to 108, 109, and 1010 bits and power per unit data rate efficiencies of 140, 60, and 2 w/Mbps. Immediate term (1-2 years) systems are feasible only in permalloy gap technology. Barring unforeseen developments, near term (3-5 years) system development is expected to employ ion implant devices and longer term (7-9 years) system development could exploit self-structured current accessed devices.© (1983) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
XMM-Newton Observations of High-Redshift Quasars*

We report on our XMM-Newton observations of the high-redshift quasars BR 2237-0607 (z = 4.558) and BR 0351-1034 (z = 4.351). We also report on XMM-Newton observations of 19 other z > 4 objects available in the public archive of which 14 were detected. We find that the optical to X-ray spectral index αox is correlated with the luminosity density at 2500 A but does not show a correlation with redshift, which is consistent with earlier results. Radio-loud quasars are brighter and have flatter X-ray slopes compared to radio-quiet quasars. There is some evidence for the jet-dominated sources to be intrinsically absorbed. The mean intrinsic 2–10 keV power-law slope of the 10 high-redshift radio-quiet quasars in our sample for which a spectral analysis can be performed is αX = 1.21 ± 0.52 (ranging between 0.32 and 1.96), which is more like the αX = 1.19 ± 0.10 found from the ASCA observations of low-redshift narrow-line Seyfert 1 galaxies (NLS1s) but different from the αX = 0.78 ± 0.11 found for low-redshift broad-line Seyfert galaxies. The steep X-ray spectral index suggests high Eddington ratios L/LEdd. These observations give credence to the hypothesis of Mathur that NLS1s are low-luminosity cousins of high-redshift quasars. Comparison with other results from the literature indicates that perhaps the most luminous quasars, from low to high redshift, have similarly steep X-ray spectra suggestive of high Eddington luminosities.
Trapezoidal-groove Schottky-gate vertical-channel GaAs FET (GaAs static induction transistor)

This letter reports, the development of a vertical-channel. GaAs FET with the unsaturated I-V characteristics of the static induction transistor (SIT) and voltage blocking capability up to 100 V. The device structure utilizes the anisotropic etching properties of GaAs, in which the gate regions are formed by a double-angle evaporation into trapezoidal etched grooves. This single evaporation step simultaneously provides both source and gate metallization, and the novel trapezoidal groove geometry automatically yields a self-aligned gate with separation of source and gate onto different levels, thus eliminating the need for critical alignment arising from source-gate interdigitation.
Symmetry violation in a superconducting film with a square array of ferromagnetic dots

We study the equilibrium state of a superconducting film covered with a regular square array of perpendicularly magnetized magnetic dots. The dots induce vortices in the film directly under them and antivortices between the dots. We show that the symmetry of the dot array is spontaneously violated by the vortices. The positions of the vortices and the antivortices depend on the magnetization and the size of the dots.
Shareholder Taxes in Acquisition Premiums: The Effect of Capital Gains Taxation

We exploit cross-temporal differences in capital gains tax rates to test whether shareholder-level capital gains taxes are associated with higher acquisition premiums for taxable acquisitions. We model acquisition premiums as a function of proxies for the capital gains taxes of target shareholders, taxability of the acquisition, and tax status of the price-setting shareholder as represented by the level of target institutional ownership. Consistent with a lock-in effect for acquisition premiums, results suggest a unique positive association between shareholder capital gains taxes for individual investors and acquisition premiums for taxable acquisitions, which is mitigated by target institutional ownership
Single‐fiber electromyography in myasthenia gravis

One-hundred-sixty single-fiber EMG studies of the extensor digitorum communis muscle were performed on 127 patients with myasthenia gravis; 131 demonstrated defective neuromuscular transmission. Jitter determinations in the biceps, deltoid or frontalis muscles increased the diagnostic yield significantly. Evoked-potential EMG studies were abnormal in less than 50 percent of patients in whom they were performed. The most sensitive criterion of abnormality was the percentage of fibers with increased jitter; the sensitivity of the test was enhanced, however, if the mean jitter of the tested muscle was also used as a criterion of abnormality. Since increased jitter may also be seen in primary muscle and nerve disease, these disorders must be excluded by other means before diagnosing myasthenia gravis on the basis of the single-fiber studies.
Fatty acid binding receptors and their physiological role in type 2 diabetes.

G-protein-coupled receptors (GPCRs) respond to various physiological ligands such as photons, ions, and small molecules that include amines, fatty acids, and amino acids to peptides, proteins and steroids. Therefore, this family of proteins represents an attractive target for biopharmaceutical research [1]. The physiological role of fatty acids and other lipid molecules as important signal mediators is well studied in various metabolic pathways [2]. Acute administration of free fatty acids (FFAs) stimulates insulin release. Conversely, chronic exposure to high levels of free fatty acids leads to impairment of β cell function and lipotoxicity. However, the receptors through which these fatty acids and lipids act were unknown, until the identification of fatty acid binding receptors: GPR40, GPR41, GPR43, and GPR119. Based on their tissue-expression profile, and pharmacologic analysis, the fatty acid binding receptors along with lipid binding receptor GPR119 are linked to diabetes and obesity. They play a critical role in the metabolic regulation of insulin release and glucose homeostasis. In this review, the mechanism of receptor activation, pharmacology, and the physiological functions of the fatty acid binding receptors will be discussed.
Time-Space Tradeoff in Derandomizing Probabilistic Logspace

Nisan [6] showed that any randomized logarithmic space algorithm (running in polynomial time and with two-sided error) can be simulated by a deterministic algorithm that runs simultaneously in polynomial time and Θ(log2 n) space. Subsequently Saks and Zhou [9] improved the space complexity and showed that a deterministic simulation can be carried out in space Θ(log1.5 n). However, their simulation runs in time \(n^{\Theta({\rm log}^{0.5} n)}\). We prove a time-space tradeoff that interpolates these two simulations. Specifically, we prove that, for any 0≤ α ≤ 0.5, any randomized logarithmic space algorithm (running in polynomial time and with two-sided error) can be simulated deterministically in time \(n^{O(log^{0.5-\alpha}n)}\) and space O(log 1.5 + α n). That is, we prove that BPL ⊆ DTISP[\(n^{O(log^{0.5-\alpha}n)}\), O(log 1.5 + α n)].
Pictet-spengler reactions in aprotic media. The total synthesis of (±) suaveoline

Abstract The first total synthesis of the indole alkaloid (±)-suaveoline 1 (a macroline-related base and a member of the sarpagine/ajmaline class of alkaloids) was completed in a stereocontrolled fashion. The serial synthesis employed three intramolecular reactions, the Pictet-Spengler cyclization ( 11 → 20 ), the Dieckmann condensation ( 21 → 22 ) and the orthoester Claisen rearrangement ( 25 → 30 ), all of which occurred with high stereoselectivity. Construction of the unique 3,4,5-trisubstituted pyridine ring ( E ) of 1 was executed by addition of hydroxylamine hydrochloride to an ethanolic solution of the corresponding 1,5-daildehyde 36 which was followed by heating. The related base (±)-N b -methylsuaveoline 38 was prepared from 37 via catalytic devenzylation (Pd/C, H 2 ) in the presence of formic acid (78% yield).
Numerical analysis of flow through oscillating cascade sections

The design of turbomachinery blades requires the prevention of flutter for all operating conditions. However, flow field predictions used for aeroelastic analysis are not well understood for all flow regimes. The present research focuses on numerical solutions of the Euler and Navier-Stokes equations using an ADI procedure to model two-dimensional, transonic flow through oscillating cascades. The model prescribes harmonic pitching motions for the blade sections for both zero and nonzero interblade phase angles. The code introduces the use of a deforming grid technique for convenient specification of the perioidic boundary conditions. Approximate nonreflecting boundary conditons were coded for the inlet and exit boundary conditions. Sample unsteady solutions were performed for an oscillating cascade and compared to experimental data. Also, test cases were run for a flat plate cascade to compare with the unsteady, small-perturbation, subsonic analysis. The predictions for oscillating cascades with nonzero interblade phase angle cases, which were near a resonant condition, differ from the experiment and theory. The zero degree interblade phase angle cases, which were near a resonant condition, differ from the experiment and theory. Studies on reflecting versus nonreflecting inlet and exit boundary conditions show that the treatment of the boundary can have a significant effect on the first harmonic, unsteady pressure distribution for certain flow conditions.
An optimal gap theorem

By solving the Cauchy problem for the Hodge-Laplace heat equation for d-closed, positive (1,1)-forms, we prove an optimal gap theorem for Kahler manifolds with nonnegative bisectional curvature which asserts that the manifold is flat if the average of the scalar curvature over balls of radius r centered at any fixed point o is a function of o(r−2). Furthermore via a relative monotonicity estimate we obtain a stronger statement, namely a ‘positive mass’ type result, asserting that if (M,g) is not flat, then \(\liminf_{r\to\infty} \frac {r^{2}}{V_{o}(r)}\int_{B_{o}(r)}\mathcal{S}(y)\, d\mu(y)>0\) for any o∈M.
Influence of Geometry and Heat Release on Counterflow Diffusion Flames: A Navier-Stokes Model

A Navier-Stokes simulation of the opposed jet counterflow diffusion flame (CFDF) using a fuel-lean methane jet is described in this work. Plug flow (PLF) and parabolic flow (PAF) jet exit velocity profiles have been used in the simulation, and the results show that changing the velocity profile has a large influence on flame stretch. Flame stretch was also found to be strongly dependent on the jet separation distance. Flame stretch increased as jet separation decreased. Comparing non-reacting and reacting cases indicated that heat release in the flame zone modifies the velocity profile and hence the strain. The flame responded easily to changes in variables such as fuel/air jet velocity ratio, and the nitrogen coflow. The flame was also sensitive to the arrangement of the side walls that encloses the CFDF burner.