cssi/SciSciGPT-SciSciNet huggingface dataset:
Gas dynamics in high-luminosity polarized 3He targets using diffusion and convection

The dynamics of the movement of gas is discussed for two-chambered polarized He-3 target cells of the sort that have been used successfully for many electron scattering experiments. A detailed analysis is presented showing that diffusion is a limiting factor in target performance, particularly as these targets are run at increasingly high luminosities. Measurements are presented on a new prototype polarized He-3 target cell in which the movement of gas is due largely to convection instead of diffusion. NMR tagging techniques have been used to visualize the gas flow, showing velocities along a cylindrically-shaped target of between 5-80 cm/min. The new target design addresses one of the principle obstacles to running polarized He-3 targets at substantially higher luminosities while simultaneously providing new flexibility in target geometry.
Fitness versus longevity in age-structured population dynamics.

We examine the dynamics of an age-structured population model in which the life expectancy of an offspring may be mutated with respect to that of the parent. While the total population of the system always reaches a steady state, the fitness and age characteristics exhibit counter-intuitive behavior as a function of the mutational bias. By analytical and numerical study of the underlying rate equations, we show that if deleterious mutations are favored, the average fitness of the population reaches a steady state, while the average population age is a decreasing function of the average fitness. When advantageous mutations are favored, the average population fitness grows linearly with time t, while the average age is independent of the average fitness. For no mutational bias, the average fitness grows as $t^{2/3}$.
Design of an Integrated Services Packet Network

The Integrated Services Digital Network (ISDN) has been proposed as a way of providing integrated voice and data communications services on a universal or near-universal basis. In this paper, I argue that the evolutionary approach inherent in current ISDN proposals is unlikely to provide an effective long-term solution and I advocate a more revolutionary approach, based on the use of advanced packet-switching technology. The bulk of this paper is devoted to a detailed description of an Integrated Services Packet Network (ISPN), which I offer as an alternative to current ISDN proposals.
Multicomponent droplet vaporization in a high temperature gas

The problem of transient vaporization of a multicomponent droplet in a hot convective environment is examined. A simplified model which accounts for liquid-phase internal circulation, transient droplet diffusion, and axisymmetric gas-phase convection is obtained. The results are in close agreement with the results of a more detailed model. The present simplified model is also compared with several existing gas-phase and liquid-phase models. The spherical diffusion limit model and the present simplified model are recommended for stagnant and convective situations, respectively. Attempts have been made to compare the results of the various models with the existing experimental data. Due to large scattering in the experimental measurements, no final conclusion can be drawn based on the experimental data.
Mixed Cations and Structural Complexity in (Eu1−xCax)4In3Ge4 and (Eu1−xCax)3In2Ge3—The First Two Members of the Homologous Series A2[n+m]In2n+mGe2[n+m] (n, m = 1, 2, ...∞; A = Ca, Sr, Ba, Eu, or Yb)

Reported are the synthesis and the structural characterization of two members of a new homologous series of polar intermetallic compounds, which exist only with mixed alkaline-earth and rare-earth metal cations. Crystals of (Eu(1-x)Ca(x))(4)In(3)Ge(4) (0.35(1) <or= x <or= 0.70(1)) and (Eu(1-x)Ca(x))(3)In(2)Ge(3) (0.78(1) <or= x <or= 0.90(1)) have been grown using a molten In metal flux and structurally characterized by single-crystal X-ray diffraction. (Eu(1-x)Ca(x))(4)In(3)Ge(4) adopts the monoclinic Mg(5)Si(6)-type structure (space group C2/m, Z = 2, Pearson symbol mS22) with lattice parameters a = 16.874(1)-17.024(2) A, b = 4.496(3)-4.556(1) A, c = 7.473(4)-7.540(1) A, and beta = 107.306(10)-105.631(3) degrees . (Eu(1-x)Ca(x))(3)In(2)Ge(3) crystallizes with a novel orthorhombic structure (space group Pnma, Z = 4, Pearson symbol oP32) with lattice parameters in the ranges a = 7.382(2)-7.4010(9) A, b = 4.452(1)-4.4640(6) A, and c = 23.684(6)-23.734(3) A, depending on the Eu/Ca ratio. The polyanionic substructures in both cases are related and are based on InGe(4) edge-shared tetrahedra, Ge(2) dimers, and bridging In atoms in a nearly square-planar environment. The (Eu(1-x)Ca(x))(4)In(3)Ge(4) structure can be viewed as a 1:1 intergrowth of Mo(2)FeB(2)-like and TiNiSi-like fragments, whereas (Eu(1-x)Ca(x))(3)In(2)Ge(3) can be rationalized as a 2:1 intergrowth of the same structural motifs. Both phases exhibit fairly wide homogeneity ranges and exist only with mixed cations. The experimental results have been complemented by linear muffin-tin orbital tight-binding band structure calculations, as well as an analysis of the observed cationic site preferences.
An Improved Oxidation Method for the Synthesis of Azodicarbonyl Compounds

Abstract Five representative hydrazo compounds have been oxidized in high yield using Br2 and pyridine. Yields range from 80% to 93%. For the synthesis of dibenzyl azodicarboxylate, this process produced analytically pure material directly from the reaction mixture.
Radial segregation induced by natural convection and melt/solid interface shape in vertical bridgman growth

The roles of natural convection in the melt and the shape of the melt/solid interface on radial dopant segregation are analyzed for a prototype of vertical Bridgman crystal growth system by finite element methods that solve simultaneously for the velocity field in the melt, the shape of the solidification isotherm, and the temperature distribution in both phases. Results are presented for crystal and melt with thermophysical properties similar to those of gallium-doped germanium in Bridgman configurations with melt below (thermally destabilizing) and above (stabilizing) the crystal. Steady axisymmetric flow are classified according to Rayleigh number as either being nearly the growth velocity, having a weak cellular structure or having large amplitude cellular convention. The flows in the two Bridgman configurations are driven by different temperature gradients and are in opposite directions. Finite element calculations for the transport of a dilute dopant by these flow fields reveal radial segregation levels as large as sixty percent of the mean concentration. Segregation is found most severe at an intermediate value of Rayleigh number above which the dopant distribution along the interface levels as the intensity of the flow increases.
2T Physics Formulation of Superconformal Dynamics Relating to Twistors and Supertwistors

Abstract The conformal symmetry SO(d,2) of the massless particle in d dimensions, or superconformal symmetry OSp N|4 , SU(2,2|N), OSp(8|N) of the superparticle in d=3,4,6 dimensions respectively, had been previously understood as the global Lorentz symmetry and supersymmetries of 2T physics in d+2 dimensions. By utilizing the gauge symmetries of 2T physics, it is shown that the dynamics can be cast in terms of superspace coordinates, momenta and theta variables or in terms of supertwistor variables a la Penrose and Ferber. In 2T physics these can be gauge transformed to each other. In the supertwistor version the quantization of the model amounts to the well known oscillator formalism for non-compact supergroups.
Is there New Physics in $B$ Decays?

Rare decays of the B meson are sensitive to new physics effects. Several experimental results on these decays have been difficult to understand within the Standard Model (SM) though more precise me...
Mechanism of friction

Abstract The origin of the frictional force is discussed. In particular, it is shown that in at least some cases e.g., copper surfaces which have been exposed to air, some mechanism other than adhesion must make the major contribution to the frictional force. Plastic deformation of the surface due to the interaction between asperities appears to provide a reasonable mechanism. It is shown that a mechanism of this sort can account, in a semiquantitative way, for the frictional force between electropolished copper surfaces at light loads.
Combining the α1 -adrenergic receptor antagonist, prazosin, with the β-adrenergic receptor antagonist, propranolol, reduces alcohol drinking more effectively than either drug alone.

Background Evidence suggests that activation of the noradrenergic system may contribute to alcohol drinking in animals and humans. Our previous studies demonstrated that blocking α1-adrenergic receptors with the antagonist, prazosin, decreased alcohol drinking in rats under various conditions. Since noradrenergic activation is also regulated by β-adrenergic receptors, we now examine the effects of the β-adrenergic receptor antagonist, propranolol, alone or in combination with prazosin, on alcohol drinking in rats selectively bred for high voluntary alcohol intake and alcohol preference (P line).
Gravitational Lensing Limits on the Average Redshift of Gamma-Ray Bursts

The lack of bright host galaxies in several recently examined gamma-ray burst (GRB) error boxes suggests that the redshifts of cosmological GRBs may be significantly higher than previously hypothesized. On the other hand, the nondetection of multiple images in the Fourth BATSE Gamma-Ray Burst Catalog (hereafter 4B catalog) implies an upper limit to the average redshift z of GRBs. Here we calculate an upper limit to z, independent of the physical model for GRBs, using a new statistical lensing method that removes distance ambiguities and thus permits accurate computation of the lensing rate at high z. The upper limit on z depends directly on the cosmological parameters Ω and Λ. If there are no multiple images among the brightest 80% of the first 1802 bursts in the 4B catalog, then, at the 95% confidence level, z<2.2,2.8,4.3, or 5.3 for (Ω, Λ) values of (0.3, 0.7), (0.5, 0.5), (0.5, 0.0), or (1.0, 0.0), respectively. The 68% upper limit to the average redshift is comparable to or less than the median redshift of GRBs in scenarios in which the GRB rate is proportional to the rate of star formation, for any cosmology. The uncertainty in the lensing rate—arising from uncertainties in the cosmological parameters and in the number density and average velocity dispersion of galaxies—will be reduced significantly in the next few years by a new generation of experiments and surveys. Moreover, the continued increase in the number of GRBs observed by BATSE will greatly constrain their redshift distribution.
The nursing information systems: collaborative design of healthcare information systems

This paper will describe a participatory design process by which individuals from many levels of hierarchy and diverse technical background envisioned and then determined the design criteria for the software system to support the delivery of high quality nursing services.
Aggregation in dilute solutions of high molar mass poly(ethylene) oxide and its effect on polymer turbulent drag reduction

Abstract We apply methods of dynamic light scattering (DLS) and fluid mechanics to quantitatively establish the role of aggregation in the turbulent drag reduction of high molar mass poly(ethylene oxide) (PEO) solutions. By means of DLS, we show that the dilute aqueous solutions of high molar mass PEO ( M w ∼ 4 × 10 6 g/mol) are aggregated and that this aggregate structure can be manipulated by addition of the chaotropic salt guanidine sulfate (GuS) or the divalent salt magnesium sulfate (MgSO 4 ). In aqueous solution, we find Γ ∼ q 2.8±0.1 , where Γ is the DLS correlation function relaxation rate and q is the scattering vector. This scaling is consistent with internal motions of a large coil or aggregate. Addition of salt progressively decreases the scaling to Γ ∼ q 2.0±0.1 (at 0.5 M of MgSO 4 ) consistent with center-of-mass diffusion of isolated coils. We further find that manipulating the aggregation state of PEO with MgSO 4 shifts the critical condition for onset of turbulent drag reduction at dilute concentrations in pipe flow by a factor of 2.5. Because this critical condition is inversely proportional to the viscoelastic relaxation time of the polymer solution, we conclude that the aggregation state and the turbulent drag reduction behavior of PEO are strongly correlated. This correlation definitively confirms prior speculation (Cox et al. Nature 1974;249; Vlachogiannis et al. Physics of Fluids 2003;15(12)) that the high molar mass PEO commonly used in literature studies of turbulent drag reduction is in a state of aggregation. Furthermore, the quantitative differences in quiescent DLS characterization and turbulent flow pressure drop measurements suggest that high molar mass PEO undergoes flow-induced de-aggregation in transport systems with shear stresses as low as 0.5 Pa.
Quantum Spheres As Groupoid C*-algebras

We show that the C*-algebra of a quantum sphere $C(S_{q}^{2n+1})$ can be realized as a groupoid C*-algebra of a groupoid which is explicitly identified and is independent of the parameter $q$.
TALON - The Telescope Alert Operation Network System : intelligent linking of distributed autonomous robotic telescopes

The internet has brought about great change in the astronomical community, but this interconnectivity is just starting to be exploited for use in instrumentation. Utilizing the internet for communicating between distributed astronomical systems is still in its infancy, but it already shows great potential. Here we present an example of a distributed network of telescopes that performs more efficiently in synchronous operation than as individual instruments. RAPid Telescopes for Optical Response (RAPTOR) is a system of telescopes at LANL that has intelligent intercommunication, combined with wide-field optics, temporal monitoring software, and deep-field follow-up capability all working in closed-loop real-time operation. The Telescope ALert Operations Network (TALON) is a network server that allows intercommunication of alert triggers from external and internal resources and controls the distribution of these to each of the telescopes on the network. TALON is designed to grow, allowing any number of telescopes to be linked together and communicate. Coupled with an intelligent alert client at each telescope, it can analyze and respond to each distributed TALON alert based on the telescopes needs and schedule.
An approximate version of the Jordan von Neumann theorem for finite-dimensional real normed spaces

It is known that any normed vector space which satisfies the parallelogram law is actually an inner product space. For finite-dimensional normed vector spaces over , we formulate an approximate version of this theorem: if a space approximately satisfies the parallelogram law, then it has a near isometry with Euclidean space. In other words, a small von Neumann Jordan constant for yields a small Banach–Mazur distance with , . Finally, we examine how this estimate worsens as increases, with the conclusion that grows quadratically with .
Palladium-Catalyzed Synthesis of 2,1‘-Disubstituted Tetrahydrofurans from γ-Hydroxy Internal Alkenes. Evidence for Alkene Insertion into a Pd−O Bond and Stereochemical Scrambling via β-Hydride Elimination

Palladium-catalyzed reactions of γ-hydroxy internal acyclic alkenes with aryl bromides afford 2,1‘-disubstituted tetrahydrofurans in good yields with diastereoselectivities of 3−5:1. The analogous transformations of substrates bearing internal cyclic alkenes afford fused bicyclic and spirocyclic tetrahydrofuran derivatives in good yields with excellent diastereoselectivities (>20:1). A series of deuterium labeling experiments indicate that the origin of the modest diastereoselectivity in reactions of acyclic internal alkene substrates likely derives from a series of reversible β-hydride elimination and σ-bond rotation processes that occur following a rare intramolecular alkene syn-insertion into an intermediate Pd(Ar)(OR) complex. In addition, these studies shed light on the chemoselectivity of insertion, suggesting that the alkene inserts into the Pd−O bond in preference to the Pd−C bond.
Tolerance analysis versus image quality: a case study for cost-effective space optics

Space optical systems generally require near-theoretical performance in hostile environments within size, weight, and cost constraints. We have addressed the challenge of achieving an optimum image quality through a cost-effective tolerance analysis scheme. Two different space optical systems are considered: the UV imager for the International Solar Terrestrial Physics (ISTP) Mission and an afocal telescope for the Advanced Polarized IR Imaging Sensor (APIRIS). These systems are described along with their required performances and designs. A tolerance study is conducted, and the effect of tolerances on image quality and cost is presented.
Stabilization Programs and External Enforcement: Experience from the 1920s

Credibility and financing problems are important reasons why countries may seek to involve external institutions in the design and implementation of stabilization programs. In particular, governments may rely on external institutions to "enforce" programs that would otherwise lack credibility. This paper analyzes six European currency stabilizations sponsored by the League of Nations in the 1920s. It emphasizes the means by which the League provided a "commitment technology" and enforced compliance, thereby helping to ensure successful stabilizations. Empirical evidence indicates that countries with greater credibility problems relied more heavily on external enforcement to stabilize their currencies.
Dynamics of Rate-of-Return Regulation

Under rate-of-return regulation, a firm's product prices are constrained by the requirement that investors not earn more than an allowable return on the firm's assets. This paper examines the dynamic properties of the rate-of-return regulation process when the regulated firm periodically undertakes new capacity investments. Our analysis identifies prices that correspond to stationary values of the regulation process. It is shown that the underlying depreciation rules for property, plant, and equipment determine whether these stationary prices will be above, equal to, or below the long-run marginal cost of providing the regulated service. We provide conditions under which the rate-of-return regulation process is dynamically stable so that prices indeed converge to their stationary values. The overall efficiency of this regulation method is shown to depend on how well the applicable depreciation schedule matches the productivity pattern of the assets in use. This paper was accepted by Gerard P. Cachon, accounting.
The ethics of tolerance and the evolution of smoking and gambling as public policy issues

Since 1964, there has been an expansion in the amount and the variety of state-sponsored and state-sanctioned gambling opportunities throughout the US. At the same time, the number of laws prohibiting cigarette smoking have grown enormously. It is striking how one of these activities is “tolerated” even encouraged by public policy makers while the other is rapidly being prohibited by them. This paper will examine this phenomenon in three parts: (1) defining what is meant by the ethics of tolerance and contrasting it with the ethics of sacrifice; (2) giving a brief historical synopsis of how the gambling and smoking issues have evolved over time; (3) drawing the implications of a shift to an ethics of tolerance on future public policy issues.
Nonequilibrium Green's function formulation of quantum transport theory for multi-band semiconductors

Abstract We present a nonequilibrium Green's function formulation of many-body quantum transport theory for multi-band semiconductor systems with a phonon bath. The equations are expressed exactly in terms of single particle nonequilibrium Green's functions and self-energies, treating the open electron–hole system in weak interaction with the bath. A decoupling technique is employed to separate the individual band Green's function equations of motion from one another, with the band–band interaction effects embedded in “cross-band” self-energies. This nonequilibrium Green's function formulation of quantum transport theory is amenable to solution by parallel computing because of its formal decoupling with respect to inter-band interactions. Moreover, this formulation also permits coding the simulator of an n-band semiconductor in terms of that for an (n−1)-band system, in step with the current tendency and development of programming technology. Finally, the focus of these equations on individual bands provides a relatively direct route for the determination of carrier motion in energy bands, and to delineate the influence of intra- and inter-band interactions. A detailed description is provided for three-band semiconductor systems.
Validity and reliability of the glottal function index.

Objective To evaluate a symptom-focused vocal impairment instrument for the evaluation of patients with voice disorders. Design Prospective, nonrandomized study of patients with voice disorders undergoing treatment with validation of a new symptom index, the Glottal Function Index (GFI). Setting Voice disorders clinic at an academic tertiary care hospital. Patients Consecutive patients undergoing therapy for glottal insufficiency, adductor spasmodic dysphonia, nodules, and granuloma (40 patients in each group) and 40 control patients. Interventions The Pearson correlation coefficient was used to evaluate GFI reproducibility and to compare it with the Voice Handicap Index (VHI). The paired-samples t test was used to compare pretherapy and posttherapy GFI values. Main Outcome Measures Correlation of GFI with VHI; comparison of the GFI in normals, and in pretherapy and posttherapy GFI and VHI scores. Results The mean ± SD normative GFI score was 0.87 ± 1.32. The correlation coefficient for GFI between independent pretherapy measurements was 0.56 ( P P P Conclusions The GFI is a reliable, reproducible, 4-item, self-administered symptom index with excellent criterion-based and construct validity. Its advantages over existing indexes include brevity and ease of administration. The GFI is a useful adjunct in the evaluation and treatment of patients with glottal dysfunction.
The affinities of hesperornis

IN the autumn of 1870, I discovered, in the Cretaceous of Western Kansas, the remains of a very large swimming-bird, which in many respects is the most interesting member of the class hitherto found, living or extinct. During the following year, other specimens were obtained in the same region, and one of them—a nearly perfect skeleton—I named Hesperornis regalis.1 In subsequent careful researches, extending over several years, I secured various other specimens in fine preservation, from the same horizon and the same general region, and thus was enabled to make a systematic investigation of the structure and affinities of the remarkable group of birds of which Hesperornis is the type. The results of this and other researches were brought together in 1880, in an illustrated monograph.2
Heat transfer from axisymmetric sources at the surface of a rotating disk

Abstract Heat transfer from axisymmetric heat sources at the surface of a rotating disk is investigated under laminar flow conditions for incompressible flow with constant physical properties. The energy equation including radial conduction is solved numerically assuming that both natural convection and viscous dissipation effects are negligible. The successive overrelaxation technique used is found to be unconditionally stable. A solution can be obtained for any specified radial surface distribution of either temperature or heat flux. Several boundary conditions are presented, including two for which an exact solution exists. The heat-transfer coefficients obtained for an isothermal disk and for the case of a power law temperature distribution are found to be in excellent agreement with existing solutions. In the present work, the temperature field and surface heat flux are obtained for the case of a circular band source (heated ring) of arbitrary width on an adiabatic disk surface. Results obtained for various Prandtl numbers and source widths indicate the existence of a conduction dominated region at low Reynolds number and a convection dominated region at high Reynolds numbers. Correlations between surface heat flux and wall shear stress over the heat source, as well as the temperature field in the vicinity of the disk surface, are also given.
Quest for Fast Partial Search Algorithm

The Grover quantum algorithm can find a target item in a database faster than any classical algorithm. In partial search, one trades accuracy for speed, and a part of the database (a block) containing the target item can be found even faster. We consider different partial search algorithms and argue that the algorithm originally suggested by Grover and Radhakrishnan and modified by Korepin is the optimal one. The efficiency of an algorithm is measured by the number of queries to the oracle.
Robustness, generality and efficiency of optimization algorithms in practical applications

The design of most engineering systems is a complex and time-consuming process. In addition, the need to optimize such systems where multidisciplinary analysis and design procedures are required can cost additional human and computational resources if proper software and numerical algorithms are not used. Several computational aspects of optimization algorithms and the associated software must be considered while making comparative studies and selecting a suitable algorithm for practical applications. Several parameters, such asaccuracy, generality, robustness, efficiency and ease of use, must be considered while deciding the superiority of an optimization approach. Approximate algorithms without sound mathematical basis can be sometimes more efficient for a specific problem, but fail to satisfy other requirements. They are, therefore, not suitable for general applications. An objective of the paper is to emphasize the critical importance of the above-mentioned parameters in large scalestructural optimization and other applications. Theoretical foundations of two promising approaches, thesequential quadratic programming (SQP) andoptimality criteria (OC), are presented and analysed. Recent numerical experiments and experiences with the SQP algorithm satisfying these requirements are described by solving a variety of structural design problems. An important conclusion of the paper is that the SQP method with a potential constraint strategy is a better choice as compared to the currently prevalent mathematical programming (MP) and OC approaches.
New dimensions in satellite hydrology

Consideration of the use of remote sensing technology applied from satellites to obtain information for the rapid and continuing assessment of the hydrologic cycle. A detailed account is given of the hydrological information made available through the activities of the ERTS-1 satellite, an experimental satellite entirely devoted to earth resources observations, and the NOAA-2 satellite, a high-resolution operational environmental satellite. Following a description of the satellites and their payloads, it is shown how with their aid information can be obtained regarding atmospheric moisture, surface water and snow cover, glaciers, potential flood situations, and subsurface water fluctuations. In addition, the use of the ERTS-1 and NOAA-2 satellites in watershed characterization and modeling and in monitoring water quality is discussed.
Iridium(I)-catalyzed regio- and enantioselective decarboxylative allylic amidation of substituted allyl benzyl imidodicarbonates.

The first Ir(I)-catalyzed decarboxylative allylic amidation of allyl benzyl imidodicarbonates is described. The reaction requires Ir(I), chiral phosphoramidite ligand, and DBU as well as proton sponge, and proceeds with excellent regio- and enantioselectivities to afford the branched 1-(aryl/alkyl)-1-benzyloxycarbonylaminoprop-2-ene in good to excellent yields. The scope, mechanism, and synthetic applications of the developed catalytic reaction are discussed.
Characterizing Charge Diffusion in CCDs with X‐Rays

ABSTRACT We demonstrate the effectiveness of two techniques for using X‐rays to evaluate the amount of charge diffusion in charge‐coupled devices (CCDs). We quantify the degree of charge diffusion with two parameters: \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape $\sigma _{d}$ \end{document} , the standard deviation for a Gaussian diffusion model, and Q, a ratio of the point‐spread function (PSF) peak to its wings. The parameters \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{b...
Study of Heat and Mass Transfer in a Vertical-Tube Evaporative Cooler

Evaporative coolers are three-fluid heat exchangers employed for heat rejection to the environment. A mixture of air and recirculating water is used as the cooling medium. These coolers are considered viable routes for improving thermal efficiencies of power-generating and referigeration cycles. The heat- and mass-transfer processes taking place in a vertical-tube evaporative cooler are studied. A steady-state, one-dimensional model of cooler performance is formulated. This model is validated by experimental measurements, taken in a single-tube exchanger, of the controlling heat- and mass-transfer coefficients. These coefficients occur at the air-water interface. Heat fluxes and enhancement ratios for conditions of interest are measured and calculated, and the results are compared and discussed. The model is found to adequately predict heat-exchanger performance.
gem-Diacetates as carbonyl surrogates for asymmetric synthesis. Total syntheses of sphingofungins E and F.

The equivalent of an asymmetric addition to a carbonyl group with a stabilized anion is accomplished by discriminating between the enantiotopic C−O single bonds of a gem-diacetate. In this way, enantioselective total syntheses of two antifugal agents, sphingofungins E and F, have been accomplished. The synthetic strategy is based on a series of catalytic processes whereby all of the chiral centers are created with high stereoselectivities. The first two stereocenters are introduced by an asymmetric allylic alkylation reaction of gem-diacetate 9 with azlactone 10. The complex of Pd(0) and ligand 14 efficiently catalyzes this key reaction, which differentiates both the enantiotopic leaving groups of a gem-diacetate and enantiotopic faces of the enolate of an azlactone in high enantiomeric excess and diastereomeric excess. From these two stereocenters, the configurations of the remaining two centers are set by a diastereoselective Os(VIII)-catalyzed dihydroxylation reaction with excellent stereocontrol. The ...
A new lidar signal processor using digital techniques to provide real-time display

An accurate high speed digital data acquisition system which records lidar data on magnetic tape is discussed. It features real-time processing of the data by means of a low cost dedicated processor. The system features dual-channel recording capability, and has two built-in gain-switching amplifiers, allowing the system to accurately record the entire return signal having a dynamic range in excess of 80 dB. Dual differential inputs are used to provide excellent noise immunity.
Study of the Decomposition of Colloidal Mixed Rare Earth Hydroxycarbonate Spheres by conventional thermal treatment and by electron-beam irradiation within a high-resolution microscope †

The practical utility of colloidal particles in the processing of ceramic oxide materials demands an understanding of the decomposition of precursor compounds as they transform to the oxide. In this exposition, the transformation of mixed rare earth hydroxycarbonate colloidal spheres to the oxide is studied. Three methods are described. In one the spheres are heated in a combined thermogravimetric and differential thermal analysis system up to 1100°C. Then successive reruns were made with specimens being cooled rapidly from the temperatures where intermediate or final reaction products are formed. X-ray diffraction patterns were taken and HREM studies were made of each sample thus produced. A second series of experiments was made in which the spheres were slowly heated to 500°C in the specimen chamber of a mass spectrometer. The gaseous decomposition products were monitored continuously. The third series involved observation of the decomposition of the colloidal spheres directly in the electron microscope. The electron-beam-induced decomposition to the oxide was followed at high resolution. The results of these three decomposition studies are compared and contrasted. Untersuchung der Zersetzung von kolloidalen Hydroxidcarbonat-Teilchen gemischter Seltener Erden durch konventionelle Thermische Behandlung und durch Elektronenstrahlen in einem hochauflosenden Mikroskop Die Verwendung kolloidaler Teilchen bei der Herstellung von keramischen Materialien aus Oxiden erfordert ein Verstandnis der Zersetzung der Precursor-Verbindungen bei ihrer Umwandlung in die Oxide. In dieser Arbeit wird die Umwandlung kolloidaler Teilchen von gemischten Hydroxidcarbonaten der Seltenen Erden untersucht. Drei Methoden werden beschrieben:1. Die Kugeln werden in einer Thermoanalysenapparatur (TG, DTA) auf 1100°C erhitzt. Daran schlossen sich Versuche an, bei denen die Proben von jenen Temperaturen schnell abgekuhlt wurden, bei denen Zwischen- oder Endprodukte gebildet wurden. Rontgenaufnahmen und HREM-Untersuchungen wurden von jeder der so hergestellten Proben gemacht. 2. In einer zweiten Reihe von Versuchen wurden die Proben langsam auf 500°C in einem Massenspektrometer erhitzt und die gasformigen Zersetzungsprodukte kontinuierlich bestimmt. 3. In der dritten Versuchsreihe wird die Zersetzung der kolloidalen Teilchen direkt im Elektronenmikroskop beobachtet. Die elektronenstrahlinduzierte Zersetzung zu den Oxiden wurde bei hoher Auflosung verfolgt. Die Ergebnisse der drei Reihen werden verglichen und gegenubergestellt.
Capping off open books and the Ozsvath-Szabo contact invariant

We prove that for $n\geq2$ there exists a compact subset $X$ of the closed ball in $\mathbb{R}^{2n}$ of radius $\sqrt{2}$, such that $X$ has Hausdorff dimension $n$ and does not symplectically embed into the standard open symplectic cylinder. The second main result is a lower bound on the $d$th regular coisotropic capacity, which is sharp up to a factor of $3$. For an open subset of a geometrically bounded, aspherical symplectic manifold, this capacity is a lower bound on its displacement energy. The proofs of the results involve a certain Lagrangian submanifold of linear space, which was considered by Audin and Polterovich.
Einstein's Biggest Blunder? High-Redshift Supernovae and the Accelerating Universe

Nearly 4 years ago, two teams of observational astronomers reported that high-redshift Type Ia supernovae are fainter than expected in a decelerating or freely coasting universe. The radical conclusion that the universe has been accelerating in the past few billion years, possibly because of a nonzero value for Einstein's cosmological constant, has gripped the worlds of astronomy and physics, causing a flurry of new research. Having participated on both teams (but much more closely with one than the other), here I provide a personal, historical account of the story.
Spectroscopy and charm quark fragmentation

The large data sample accumulated at the KEKB storage ring allows for dedicated analysis in charm spectroscopy. This made the first observations of e.g. the broad D** resonances in B decays as well as other processes possible. The observation of the D sJ (2317) resonances are confirmed and indications of their quantum numbers are given. The fragmentation function for D*+ has been measured with unprecedented accuracy. PACS: 13.25.Hw – 13.66.Bc – 14.40.Lb
Spin-exchange relaxation-free magnetometry using elliptically polarized light

Spin-exchange relaxation free alkali-metal magnetometers typically operate in the regime of high optical density, presenting challenges for simple and efficient optical pumping and detection. We describe a high-sensitivity Rb magnetometer using a single elliptically polarized off-resonant laser beam. Circular component of the light creates relatively uniform spin polarization while the linear component is used to measure optical rotation generated by the atoms. Modulation of the atomic spin direction with an oscillating magnetic field shifts the detected signal to high frequencies. Using a fiber-coupled distributed feedback laser, we achieve magnetic field sensitivity of $7\text{ }\text{fT}/\sqrt{\text{Hz}}$ with a miniature $5\ifmmode\times\else\texttimes\fi{}5\ifmmode\times\else\texttimes\fi{}5\text{ }\text{mm}\text{ }\text{Rb}$ vapor cell.
Amplification versus mutation as a mechanism for reversion of an HGPRT mutation.

We have used a cloned cDNA for hypoxanthine-guanine phosphoribosyltransferase (HGPRT) to analyze the HGPRTgene and mRNA in an HGPRT-deficient mutant of Chinese hamster cells (RJK10) and its HGPRT-positive revertants. By Southern blot analysis, no DNA rearrangements were detected within the genes from any of the cell lines examined. However, four of five spontaneous revertants each contained 10-to 20-fold more copies of the HGPRTgene than did RJK10 or wild-type cells. In contrast, the gene was not amplified in four mutagen-induced revertants. The RJK10 mutation did not alter the size or concentration of HGPRT mRNA and representatives of the revertants contained the mRNA in amounts proportional to the number of genes they carried. Examples of clones with either stable or unstable gene amplification were identified and their HGPRT-positive phenotypes were shown to be dependent on the gene amplification. In a stably amplified revertant, the extra genes were found to be syntenic with the X chromosome marker glucose-6-phosphate dehydrogenase. In an unstable revertant only one of the 10 to 20 copies of the gene could be shown to be X linked. Thus, we found that RJK10 can revert by at least two distinct mechanisms: amplification of the HGPRTgene, which occurred spontaneously, or point mutation, which predominated after exposure to mutagens.
Safety in automated trust negotiation

Exchange of attribute credentials is a means to establish mutual trust between strangers wishing to share resources or conduct business transactions. Automated Trust Negotiation (ATN) is an approach to regulate the exchange of sensitive information during this process. It treats credentials as potentially sensitive resources, access to which is under policy control. Negotiations that correctly enforce policies have been called “safe” in the literature. Prior work on ATN lacks an adequate definition of this safety notion. In large part, this is because fundamental questions such as “what needs to be protected in ATN?” and “what are the security requirements?” are not adequately answered. As a result, many prior methods of ATN have serious security holes. We introduce a formal framework for ATN in which we give precise, usable, and intuitive definitions of correct enforcement of policies in ATN. We argue that our chief safety notion captures intuitive security goals. We give precise comparisons of this notion with two alternative safety notions that may seem intuitive, but that are seen to be inadequate under closer inspection. We prove that an approach to ATN from the literature meets the requirements set forth in the preferred safety definition, thus validating the safety of that approach, as well as the usability of the definition.
Simplicity and observability: When are particles elementary?

It is not possible to dismiss the atomistic paradigm because the proposed elementary particles are too many (and, hence, it is claimed, they do not provide a simple account of nature) or because it is not possible to observe quarks in an isolated manner. The developments in particle physics have brought about radical changes to our notions of simplicity and observability, and in this paper we elaborate on these changes. It is as a result of these changes that the present situation in elementary particle physics justify us to claim that we have indeed reached a level of explanation where the constituent particles (quarks, leptons, gluons, and intermediate bosons) used for the explanation of the various phenomena considered to be delineating a particular level in the descriptive framework of the physical phenomena and a specific stratum in the organization of nature, can be regarded as elementary.
The viscoelastic behavior of polymer/oligomer blends

Abstract The viscoelastic properties of poly(α-methyl styrene), its hexamer, and their athermal blends at various concentrations are studied. Master curves for the dynamic shear responses, G′ and G″, are successfully constructed for both the pure materials and the blends, indicating the validity of the time–temperature superposition principle for these systems. The temperature dependence of the shift factor follows the Vogel–Fulcher behavior over the temperature range studied, and the temperature dependence is slightly weaker for the blends. The rubbery plateau modulus scales with the polymer concentration as G N 0 ∝ ϕ 2 . 04 ± 0 . 32 ; the terminal relaxation time scales with the polymer concentration as τ d ∝ ϕ 1 . 35 ± 0 . 33 . The shape of the segmental dispersion appears unchanged by concentration, which differs from our calorimetric studies where mixtures show obviously temperature-broadened glass transitions and depressed enthalpy overshoots. The TNM (Tool-Narayanaswamy-Moynihan) model indicates that the change in the temperature dependence is not sufficient to account for the observed calorimetric broadening. We conclude that the temperature broadening of the glass transition for our blends is not due to a broadening of the dynamic spectrum or to changes in its temperature dependence. The possibility that the broadening is due to changes in the non-linearity parameter x in the TNM model is also considered. While the broadening could be due to a decreasing value of x, we found that this same decrease would lead to increasing enthalpy overshoots on heating, contrary to the experimental observations. The combination of the calorimetric results with the rheological measurements further indicates that the fundamental basis of the TNM-type of model of structural kinetics in glasses is potentially wrong.
Postseismic surface deformations due to lithospheric and asthenospheric viscoelasticity

This paper proposes a model for postseismic surface deformations by attributing them to lithospheric and asthenospheric viscoelasticity. The model predicts that the deformations due to lithospheric viscoelasticity depend on the decrease in the effective shear modulus acting long after the lithospheric relaxation compared to that acting immediately following the earthquake. While such deformations are generally smaller than those associated with asthenospheric viscoelasticity, they occur on a shorter time scale and may be in opposite direction to both the motion occurring at the time of the earthquake and that occurring as the asthenospheric relaxation occurs.
Back-up electrical power needs for residential solar water heaters

Abstract Increasing prices for electricity have resulted in a rapidly growing demand for residential solar water heating systems. Most of the solar systems being sold and installed include an electrical powered back-up heater for use during sustained periods of low solar insolation, or periods of excessive hot water use. This electrical back-up use has prompted some utilities to consider establishing very high rates for owners of solar systems. The purpose of this paper is to report on a study to simulate a typical solar installation and determine the probability that back-up power will be needed at the time the utility experiences its peak load. The result of this computer study for one geographic area provides a quantitative basis to show that there is little justification for charging solar water heater owners higher rates than other residential customers.
ENE REACTION OF C60 AND 3-METHYLENE-2,3-DIHYDROFURAN

3-Methylene-2,3-dihydrofuran adds to C{sub 60} with good yield. The adduct can be isolated from other products by flash chromatography on silica gel. The structure of the adduct was analyzed using NMR and UV-vis spectroscopies.
SOLAR NEUTRINOS. I. THEORETICAL

The principal energy source for main-sequence stars like the sun is believed to be the fusion, in the deep interior of the star, of four protons to form an alpha particle. The fusion reactions are thought to be initiated by the sequence ^1H(p, e^(+)v)^2H(p,γ)^(3)He and terminated by the following sequences: (i) ^(3)He(^(3)He, 2p)^(4)He; (ii) ^(3)He(α,γ)^(7)Be(e^(-)v)^(7)Li(p,α)^(4)He; and (iii) ^(3)He(α,γ)^(7)Be(p,γ)^(8)B(e^(+)v)^(8)Be*(α)^(4)He. No direct evidence for the existence of nuclear reactions in the interiors of stars has yet been obtained because the mean free path for photons emitted in the center of a star is typically less than 10^(-10) of the radius of the star. Only neutrinos, with their extremely small interaction cross sections, can enable us to see into the interior of a star and thus verify directly the hypothesis of nuclear energy generation in stars.
Evidence for a Cutoff in the Frequency Distribution of Solar Flares from Small Active Regions

In this paper, we present evidence that active regions with small sunspot areas have an upper limit to the energy of the flares they produce. This result is consistent with predictions of the avalanche model of Lu et al. We used data from the Hard X-Ray Burst Spectrometer on the Solar Maximum Mission to study differences in the frequency distributions of solar flares as grouped by active region characteristics. The active region parameters considered were the total sunspot area, the longitudinal extent, the Mount Wilson class, and the McIntosh class. We find that there are significantly fewer high count rate flares (104 counts s-1 above 60 keV) from regions with small sunspot areas (0-500 microhemispheres) than would be expected from a power-law extrapolation from the frequency distribution of flares with peak rates greater than 50 counts s-1 above 60 keV. This is not found in the distribution of flares produced by regions with large sunspot areas (600-3600 microhemispheres). Using our analysis of the data and the predictions of the avalanche model, we calculated a limit to the energy of a flare that can be produced by an active region with given sunspot area. There are no statistically significant differences between the frequency distributions of flares with peak count rates 103 counts s-1 grouped according to the other region characteristics studied. We also find that, in all cases, large complex regions appear to produce a lower percentage of low-energy events than do smaller, simpler regions. It is possible that this effect is the result of biases against observations of low count rate flares and the determination of their locations.
Probing quark fragmentation functions for spin 1/2 baryon production in unpolarized e+ e- annihilation

Abstract We study the measurement of the quark fragmentation functions for spin - 1 2 baryon production ( Λ and Λ , in particular) in unpolarized e+e− annihilation. The spin-dependent fragmentation functions g 1 (z) and h 1 (z) can be probed in the process as a result of quark-antiquark spin correlation and the weak decay of the baryons. The relevant cross section is expressed as a product of the two-jet cross section, the fragmentation functions, and the differential width of the hyperon decay.