cssi/SciSciGPT-SciSciNet huggingface dataset:
Synthesis of optically pure di- to tetra-substituted cyclopentanes from sugar-derived norbornene derivatives.

Abstract The chiral norbornene derivative 2 obtained from Lewis acid-catalyzed reaction of an l -arabinose-derived dienophile 1 and cyclopentadiene was oxidized with OsO 4 NaIO 4 to the dialdehyde 3 , a tetrasubstituted cyclopentane. Mild treatment of 3 with [Rh(dppp) 2 ]Cl (dppp = Ph 2 P(CH 2 ) 3 PPh 2 ] ( 4 selectively epimerized the aldehyde adjacent to the methoxycarbonyl group to give the epi-aldehyde 8 . Under more vigorous conditions, this group was decarbonylated to give the monoaldehyde 11 , and more strenuous treatment removed the second aldehyde group to give the didecarbonylated cyclopentane derivative 5 . The structure and optical purity of 5 was confirmed by its transformation into (1 S ,2 S )-cyclopentane-1,2-dicarboxylic acid ( 7 ).
Equal division of estates and the exchange motive.

Abstract Although the bequest motive is one of the most important theoretical extensions of the life-cycle hypothesis, few empirical studies have measured determinants of unequal estate division. We estimated whether several proxies that are consistent with exchange and altruism lead to unequal estate division using data from a longitudinal survey of deceased elderly persons linked to probate court records. Equal division was the rule-between 70 and 83% of estates were divided equally, depending on the strictness of the definition of equal division. Several measures of exchange were not significant predictors of unequal division. Two factors that are consistent with both exchange and altruism-writing the last will and testament within five years of death and having more children-predict unequal estate division. The models control for selection, because many decedents do not file a record in probate court.
Exchange of global mean angular momentum between an atmosphere and its underlying planet

Abstract This paper investigates the exchange of global mean angular momentum between an atmosphere and its underlying planet by a simple model. The model parameterizes four processes that are responsible for zonal mean momentum budget in the atmospheric boundary layer for a rotating planet: (i) meridional circulation that redistributes the relative angular momentum, (ii) horizontal diffusion that smoothes the prograde and retrograde winds, (iii) frictional drag that exchanges atmospheric angular momentum with the underlying planet, and (iv) internal redistribution of the zonal mean momentum by wave drag. It is shown that under a steady-state or a long-term average condition, the global relative angular momentum in the boundary layer vanishes unless there exists a preferred frictional drag for either the prograde or the retrograde zonal wind. We further show quantitatively that one cannot have either a predominant steady prograde or retrograde wind in the boundary layer of a planetary atmosphere. The parameter dependencies of the global relative angular momentum and the strength of the atmospheric circulation in the boundary layer are derived explicitly and used to explain the observational differences between the atmospheres of Earth and Venus.
A prospective analysis of incidence and severity of quadriceps inhibition in a consecutive sample of 100 patients with complete acute anterior cruciate ligament rupture

Background: Weakness of the quadriceps femoris muscle after anterior cruciate ligament (ACL) injury and reconstruction has been attributed to incomplete voluntary activation of the muscle. The literature is conflicting on the incidence of incomplete voluntary quadriceps activation after ACL injury because of differences in testing methods and population biases. The purpose of this study was to systematically examine the incidence and severity of quadriceps voluntary activation failure in both lower extremities after acute ACL injury. We hypothesized that the incidence of quadriceps inhibition would be higher in the ACL-injured limbs than the uninvolved limbs, that the incidence of inhibition in the ACL-deficient limbs would be larger than in our historical sample of healthy young individuals tested in the same manner and that there would be no difference in inhibition by gender. Study Design: Prospective, descriptive. Methods: One hundred consecutive patients with acute ACL rupture (39 women and 61 men) were tested when range of motion was restored and effusion resolved, an average of 6 weeks after injury. A burst superimposition technique was used to assess quadriceps muscle activation and strength in all patients. Dependent t-tests were used to compare side-to-side differences in quadriceps strength. Independent t-tests were used to compare incidence of activation failure by gender and make comparisons to historical data on young, active individuals. Results: The average involved side quadriceps activation was 0.92, and ranged from 0.60 to 1.00. The incidence of incomplete activation in the involved side quadriceps was 33 percent and in the uninvolved side quadriceps was 31 percent after acute ACL rupture. The incidence of incomplete activation bilaterally was 21 percent. There was no difference in incidence of quadriceps inhibition by gender. Conclusion: The incidence of voluntary quadriceps inhibition on the involved side was three times that of uninjured, active young subjects, but the magnitude was not large. The incidence of quadriceps inhibition on the uninjured side was similar to the injured side. Clinical relevance: Both the incidence and magnitude of quadriceps inhibition after ACL rupture are lower than have previously been reported. The conventional wisdom, therefore, that quadriceps inhibition is a significant problem in this population is challenged by the results of this study. Differences between this study and others include sufficient practice to ensure a maximal effort contraction and rigorous inclusion criteria. The findings have implications for strength testing as well as rehabilitation. The quadriceps index, an assessment of the injured side quadriceps strength deficit, may be affected by the presence of voluntary activation failure in the uninvolved side.
Heavy element diffusion in metal poor stars

Stellar evolution models that include the effect of helium and heavy-element diffusion have been calculated for initial iron abundances of [Fe/H] = -2.3, -2.1, -1.9, and -1.7. These models were calculated for a large variety of masses and three separate mixing lengths, α = 1.50, 1.75, and 2.00 (with α = 1.75 being the solar calibrated mixing length). The change in the surface iron abundance for stars of different masses was determined for the ages of 11, 13, and 15 Gyr. Iron settles out of the surface convection zone on the main sequence; this iron is dredged back up when the convection zone deepens on the giant branch. In all cases, the surface [Fe/H] abundance in the turnoff stars was at least 0.28 dex lower than the surface [Fe/H] abundance in giant branch stars of the same age. However, Gratton et al. recently found, based on high-dispersion spectra of stars in the globular cluster NGC 6397, that the turnoff and giant branch stars had identical (within a few percent) iron abundances of [Fe/H] = -2.03. These observations prove that heavy-element diffusion must be inhibited in the surface layers of metal-poor stars. When diffusion is inhibited in the outer layers of a stellar model, the predicted temperatures of the models are similar to those of models evolved without diffusion, while the predicted lifetimes are similar to those of stars in which diffusion is not inhibited. Isochrones constructed from the models in which diffusion is inhibited fall halfway between isochrones without diffusion and isochrones with full diffusion. As a result, absolute globular cluster ages based upon the absolute magnitude of the turnoff are 4% larger than ages inferred from full-diffusion isochrones and 4% smaller than ages inferred from non-diffusion isochrones.
Structures, Reactivities, and Antibiotic Properties of the Marinopyrroles A−F

Cultivation of actinomycete strain CNQ-418, retrieved from a deep ocean sediment sample off the coast of La Jolla, California, has provided marinopyrroles A–F. Sharing just 98% 16S rRNA gene sequence identity with S. sannurensis, the strain likely represents a new Streptomyces species. The metabolites contain an unusual 1,3′-bipyrrole core decorated with several chlorine and bromine substituents and possess marked antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA). The congested N,C-biaryl bond establishes an axis of chirality that, for marinopyrroles A-E, is configurationally stable at room temperature. Moreover, the natural products are fashioned strictly in the M-configuration. The Paal-Knorr condensation was adapted for the synthesis of the 1,3′-bipyrrole core. Halogenation of this material with N-bromosuccinimide cleanly furnished the 4,4′,5,5′-tetrahalogenated core that characterizes this class of marine-derived metabolites.
Organocatalytic multicomponent reaction for the acquisition of a selective inhibitor of mPTPB, a virulence factor of tuberculosis

Mycobacterium protein tyrosine phosphatase B (mPTPB) is essential for the survival and persistence of Mycobacterium in the host. Thus small molecule inhibitors of mPTPB are potential anti-TB agents. We developed an efficient organocatalytic multicomponent reaction (MCR) between pyrrole, formaldehyde and aniline, affording a potent and selective mPTPB inhibitor with an IC50 value of 1.5 μM and >50-fold specificity. Our studies provide a successful example of using organocatalysis as a discovery tool for the acquisition of PTP inhibitors.
The Distance to the Fornax Dwarf Galaxy Using Red Clump Stars and the Discrepancy between Red Clump and Tip of the Red Giant Branch Distances

I determine a distance to the Fornax dwarf galaxy using stars in the red clump and at the tip of the red giant branch. They are in very good agreement, with μ0 = 20.66 mag. Comparing the magnitudes of the tip of the red giant branch and of the red clump in Fornax, Carina, and the Magellanic Clouds, I propose a possible solution to the problem of the discrepancy between these two types of distance measurements.
Atmospheric particulate analysis using angular light scattering

Using the light scattering matrix elements measured by a polar nephelometer, a procedure for estimating the characteristics of atmospheric particulates was developed. A theoretical library data set of scattering matrices derived from Mie theory was tabulated for a range of values of the size parameter and refractive index typical of atmospheric particles. Integration over the size parameter yielded the scattering matrix elements for a variety of hypothesized particulate size distributions. A least squares curve fitting technique was used to find a best fit from the library data for the experimental measurements. This was used as a first guess for a nonlinear iterative inversion of the size distributions. A real index of 1.50 and an imaginary index of -0.005 are representative of the smoothed inversion results for the near ground level atmospheric aerosol in Tucson.
Semistructured Grid Generation in Three Dimensions Using a Parabolic Marching Scheme

shock impingement point, it was observed that a reduction in  ow separation behind the shock ensued as a result of weakened shock strength. Conclusions The  ow eld inside transonic compressors involves high-level  ow physics and is very sensitive to changes in blade geometry. Therefore, the design of an axial compressor blade requires careful maneuvering through complex nonlinear design space. Numerical optimization is attractive in that constraints can be imposed to prevent ill effectsof a design.Constraints,however, limits designspace, and in the case of an axial compressor blade design, a constraint on inletmass  ow rate takes toomuchspaceaway,makingoptimization extremely dif cult to perform. This Note shows that incorporating the constraint into an objective function can improve the design results. Also if needed constraints are related to the objective function in someways, it would be possiblethat they all becomea part of the objective function while discouraging the design process from moving into certain directions. The study also shows that the developed design method can improve the adiabatic ef ciency of a blade section signi cantly by reducing the losses from the passage shock and the  ow separation. The design method, however, cannot handle three-dimensional effects because it employs quasi-three-dimensional  ow physics and did not produce desired design results for the blade section near the hub region. To ascertain the signi cance of the quasi-threedimensional design results, constructing and evaluating the performance of three-dimensionalblades based on the designed sections will be conducted in the future. References 1Damle, S., Dang, T., Stringham, J., and Razinsky, E., “Practical Use of 3D Inverse Method for Compressor Blade Design,” American Society of Mechanical Engineers, ASME Paper 98-GT-115, June 1998. 2Wang,Z., Cai, R., Chen, H., and Zhang,D., “A FullyThree-Dimensional Inverse Method for Turbomachinery Blading with Navier–Stokes Equations,” American Society of Mechanical Engineers, ASME Paper 98-GT126, June 1998. 3Sorenson, R. L., “A Computer Program to Generate Two-Dimensional Grids About Airfoils and Other Shapes by Use of Poisson’s Equation,” NASA TM-81198, 1980. 4Chima, R. V., “Explicit Multigrid Algorithm for Quasi-ThreeDimensionalViscous Flows in Turbomachinery,”Journalof Propulsion and Power, Vol. 3, No. 5, 1987, pp. 397–405. 5Wilcox, D. C., “Comparison of Two-Equation Turbulence Models for Boundary Layers with Pressure Gradient,” AIAA Journal, Vol. 31, No. 8, 1993, pp. 1414–1421. 6Katsanis, T., andMcNally,W.D., “Revised FORTRANProgramforCalculating Velocities and Streamlines on the Hub-ShroudMidchannel Stream Surface of an Axial-, Radial-, and Mixed-Flow Turbomachine or Annular Duct, Part I—User’s Manual,” NASA TN D-8430, 1977. 7“DOT User’s Manual,” Ver. 3.00, VMA Engineering,Goleta, CA, 1992. 8Hicks, R. M., and Henne, P. A., “Wing Design by Numerical Optimization,” Journal of Aircraft, Vol. 15, No. 7, 1978, pp. 407–412.
New and convenient method for incorporation of pentafluorosulfanyl (SF5) substituents into aliphatic organic compounds.

Use of Et3B as a catalytic initiator allows the convenient, regiospecific, and highly stereoselective addition of SF5Cl in high yield to a variety of alkenes and alkynes.
A Flattened Protostellar Envelope in Absorption around L1157

Deep Spitzer IRAC images of L1157 reveal many of the details of the outflow and the circumstellar environment of this Class 0 protostar. In IRAC channel 4 (8 μm), there is a flattened structure seen in absorption against the background emission. The structure is perpendicular to the outflow and is extended to a diameter of ~2'. This structure is the first clear detection of a flattened circumstellar envelope or pseudodisk around a Class 0 protostar. Such a flattened morphology is an expected outcome for many collapse theories that include magnetic fields or rotation. We construct an extinction model for a power-law density profile, but we do not constrain the density power-law index.
A multi-fingered micromechanism for coordinated micro/nano manipulation

Coordinated manipulation of micro-scale objects is critical for advancing several emerging applications such as microassembly and manipulation of biological cells. Most of the existing designs for micromanipulators are designed to accomplish primarily spatial positioning functionalities using positioning stages. Relatively, there are very few micromanipulators capable of 'grip-and-place' functionality that comprises both gripping and positioning at micro-scales. However, such manipulators are generally bulky. This paper introduces a novel concept of a miniaturized micromanipulator with multiple fingers for coordinated planar manipulation that involves both gripping and positioning of micro-scale objects. In this micromanipulator, multiple independently actuated fingers coordinate with each other to accomplish the manipulation. The paper presents a systematic design of the micromanipulator through shape optimization of each finger for a rationally chosen topology and a proof-of-concept prototype of the device fabricated using conventional microfabrication processes. Experimental results characterizing the input–output behavior of a finger mechanism in the prototype device are presented and an excellent correlation between the experimental results and the theoretical results validating both the design and the fabrication of the micromanipulator prototype is demonstrated. Experiments involving coordinated manipulation of 15 µm diameter polystyrene microspheres using multiple fingers in the micromanipulator station are also presented.
Cooperation limitations under a one-time threat of expulsion and punishment

Abstract We examine the impact of one-time threats of expulsion and punishment on voluntary contributions in a public goods game. Participants played in 15-round sessions where they were allowed to vote to remove other subjects only after round 5 and in one design also voted whether to punish the remaining subjects after round 10. Consistent with the literature, we find that an additional threat of punishment increases the contributions of participants before the punishment vote. The literature shows that frequent threats of expulsion may increase efficiency in the provision of public goods. In realistic settings, however, opportunities for expulsion are limited whereas threats of non-expulsive punishments are common. We find the threat of costly punishment increases contributions with little impact on efficiency (57.1% versus 58.1%), and that standards for inclusion rise when later punishment is available.
The origin of the galaxy mass-metallicity relation and implications for galactic outflows

Using cosmological hydrodynamic simulations that dynamically incorporate enriched galactic outflows together with analytical modelling, we study the origin of the stellar mass-gas-phase metallicity relation (MZR). We find that metallicities are driven by an equilibrium between the rate of enrichment owing to star formation and the rate of dilution owing to infall of unenriched gas. This equilibrium is in turn governed by the outflow strength. As such, the MZR provides valuable insights and strong constraints on galactic outflow properties across cosmic time. We compare three outflow models: no outflows, a 'constant-wind model that emulates the popular Dekel & Silk scenario, and a 'momentum-driven wind' model that best reproduces z ≥ 2 intergalactic medium metallicity data. Only the momentum-driven wind scaling simulation is able to reproduce the observed z ∼ 2 MZR's slope, amplitude, and scatter. In order to understand why, we construct a one-zone chemical evolution model guided by simulations. This model shows that the MZR in our outflow simulations can be understood in terms of three parameters: (i) the equilibrium metallicity Z g,eq = YS FR / ACC (where y = net yield), reflecting the enrichment balance between star formation rate S FR and gas accretion rate ACC ; (ii) the dilution time t d = M g /M SFR , representing the time-scale for a galaxy to return to Z g,eq after a metallicity-perturbing interaction; and (iii) the blowout mass M blowout , which is the galaxy stellar mass above which winds can escape its halo. Without outflows, galaxy metallicities exceed observations by approximately two to three times, although the slope of the MZR is roughly correct owing to greater star formation efficiencies in larger galaxies. When outflows with mass-loading factor η w are present, galaxies below M blowout obey Z g,eq ≈ y/(1 + η w ), while above M blowout , Z g,eq → y. Our constant-wind model has M blowout ∼ 10 10 M ⊙ , which yields a sharp upturn in the MZR above this scale and a flat MZR with large scatter below it, in strong disagreement with observations. Our momentum-driven wind model naturally reproduces the observed Z g ∞ M 0.3 * because Z g,eq ∞ η -1 w ∞ M 1/3 * when η w » 1 (i.e. at low masses). The flattening of the MZR at M* ≥ 10 10.5 M ⊙ observed by Tremonti et al. is reflective of the mass-scale where η w ∼ 1 rather than a characteristic outflow speed; in fact, the outflow speed plays little role in the MZR except through M blowout . The tight observed MZR scatter is ensured when t d ≤ dynamical time, which is only satisfied at all masses in our momentum-driven wind model. We also discuss secondary effects on the MZR, such as baryonic stripping from neighbouring galaxies' outflows.
Investment Climate and FDI in Developing Countries: Firm-Level Evidence

This paper uses firm-level data across 77 developing countries to show that constraints related to investment climate hamper Foreign Direct Investment (FDI). The main results show that physical infrastructure problems, financing constraints, and institutional problems discourage FDI. These results are robust to an alternative definition of FDI, introduction of additional explanatory variables, and some breakdown analyses (different sectors of activity and comparison between Sub-Saharan Africa and other developing countries). The results also highlight that exporter foreign firms are more constrained in their activity by physical infrastructure hurdles and the lack of skilled workers compared to firms supplying the domestic market.
Surface Roughness Effects in Hydrodynamic Lubrication: The Flow Factor Method

Extension et generalisation du modele d'ecoulement moyen de Patir et Cheng pour l'obtention d'une equation de Reynolds moyenne en presence d'une rugosite de surface bidimensionnelle. Calcul des valeurs des facteurs d'ecoulement apparaissant dans le formalisme au moyen d'un developpement de perturbation de la pression dans un film parallele nominal. Accord des resultats de perturbation avec les resultats d'une simulation numerique recente jusqu'a ce que le contact de surface devienne important les deux approches devenant inadequates a ce moment-la. Mise en evidence de la dependance des facteurs d'ecoulement des parametres de rugosite sous une forme explicite simple
Beta-skeletons have unbounded dilation

A fractal construction shows that, for any β > 0, the β-skeleton of a point set can have arbitrarily large dilation. In particular this applies to the Gabriel graph.
Stratospheric Ozone: An Introduction to Its Study

An analysis is made of the various reactions in which ozone and atomic oxygen are involved in the stratosphere. At the present time, hydrogen, nitrogen, and chlorine compounds in the ranges parts per million, parts per billion, and parts per trillion may have significant chemical effects. In the upper stratosphere, above the ozone peak, where there is no strong departure from photochemical equilibrium conditions, the action of hydroxyl and hydroperoxyl radicals of nitrogen dioxide and chlorine monoxide on atomic oxygen and of atomic chlorine on ozone can be introduced. A precise determination of their exact effects requires knowledge of (1) the vertical distribution of the H2O, CH4, and H2 dissociation by reaction of these molecules with electronically excited oxygen atom O(¹D); (2) the ratio of the OH and HO2 concentrations and their absolute values, which depend on insufficiently known rate coefficients; (3) the various origins of nitric oxide production, with their vertical distributions related to latitude and season; and (4) the various sources giving different chlorine compounds that may be dissociated in the stratosphere. In the lower stratosphere, below the ozone peak, there is no important photochemical production of O3, but there exist various possibilities of transport. The predictability of the action of chemical reactions depends strongly on important interactions between OH and HO2 radicals with CO and NO, respectively, which affect the ratio n(OH)/n(HO2) at the tropopause level; between OH and NO2, which lead to the formation of nitric acid with its downward transport toward the troposphere; between NO and HO2, which lead to NO2 and its subsequent photodissociation; between ClO and NO, which also lead to NO2 and become more important than the reaction of ClO with O; and between Cl and various molecules, such as CH4 and H2, which lead to HCl with its downward transport toward the troposphere. All these chemical processes are subject to many changes since they occur in the lower stratosphere where seasonal, latitudinal, and even day-to-day variations of the ozone concentrations are observed in association with advective and dynamic transports, which depend on meteorological conditions as indicated by variations of tropopause heights.
Increasing the weight of minimum spanning trees

Abstract The problems of computing the maximum increase in the weight of the minimum spanning trees of a graph caused by the removal of a given number of edges, or by finite increases in the weights of the edges, are investigated. For the case of edge removals, the problem is shown to be NP-hard and an Ω(1/log k)-approximation algorithm is presented for it, where (input parameter) k > 1 is the number of edges to be removed. The second problem is studied, assuming that the increase in the weight of an edge has an associated cost proportional to the magnitude of the change. An O(n3m2 log(n2/m)) time algorithm is presented to solve it.
Accidents in (0,2) Landau-Ginzburg theories

We study the role of accidental symmetries in two-dimensional (0,2) superconformal field theories obtained by RG flow from (0,2) Landau-Ginzburg theories. These accidental symmetries are ubiquitous, and, unlike in the case of (2,2) theories, their identification is key to correctly identifying the IR fixed point and its properties. We develop a number of tools that help to identify such accidental symmetries in the context of (0,2) Landau-Ginzburg models and provide a conjecture for a toric structure of the SCFT moduli space in a large class of models. We also give a self-contained discussion of aspects of (0,2) conformal perturbation theory.
Evaluating state tax revenue variability: a portfolio approach

This article develops a volatility model based on portfolio theory to examine state tax revenue variability. Unlike traditional parametric methods used to analyse state tax revenue variability, the portfolio approach allows the computation of a tax's share of total tax revenue that minimizes the overall variability in total state tax revenue given a state's portfolio of tax revenue sources. The model can thus be used to evaluate how closely a state's revenue portfolio is constructed to minimize variability in total state tax revenue. An empirical application of the model is conducted on a sample of US states. The volatility model presented here serves as a useful complement to parametric techniques that have been used to estimate tax revenue variability.
The Astrosphere of the Asymptotic Giant Branch Star Irc+10216

We have discovered a very extended shock structure (i.e., with a diameter of about 24') surrounding the well-known carbon star IRC+10216 in ultraviolet images taken with the Galaxy Evolution Explorer satellite. We conclude that this structure results from the interaction of IRC+10216's molecular wind with the interstellar medium (ISM), as it moves through the latter. All important structural features expected from theoretical models of such interactions are identified: the termination shock, the astrosheath, the astropause, the bow shock, and an astrotail (with vortices). The extent of the astropause provides new lower limits to the envelope age (69,000 years) and mass (1.4 M {sub sun}, for a mass-loss rate of 2 x 10{sup -5} M {sub sun} yr{sup -1}). From the termination-shock standoff distance, we find that IRC+10216 is moving at a speed of about {approx}>91 km s{sup -1} (1 cm{sup -3}/n {sub ISM}){sup 1/2} through the surrounding ISM.
Advanced far-infrared detectors

Recent advances in photoconductive and bolometric semiconductor detectors for wavelengths 1 mm >λ > 50 μm are reviewed. Progress in detector performance in this photon energy range has been stimulated by new and stringent requirements for ground based, high altitude (airplane and balloon based) and space-borne telescopes for astronomical and astrophysical observations. The paper consists of chapters dealing with the various types of detectors: Be and Ga doped Ge photoconductors, stressed Ge:Ga devices and neutron transmutation doped Ge thermistors. Advances in the understanding of basic detector physics and the introduction of modern semiconductor device technology have led to predictable and reliable fabrication techniques. Integration of detectors into functional arrays has become feasible and is vigorously pursued by groups worldwide.
Geometrically-exact, intrinsic theory for dynamics of moving composite plates

A geometrically-exact and fully intrinsic theory is presented for dynamics of composite plates undergoing large deformation. To say that the formulation is intrinsic means that it is without displacement and rotation variables. Although the equations are geometrically-exact, the highest degree nonlinearities are quadratic; there are no singularities associated with finite rotation. Methods for posing problems in this framework along with advantages of the formulation are discussed.
Formation and structure of epitaxial NiSi2 and CoSi2

Abstract Transmission electron microscopy has been applied to study the formation and structure of epitaxial NiSi2 and CoSi2 thin films on silicon. Bright field and dark field imaging reveal the interface planes of faceted silicides through the strain contrast, analogous to the contrast of the precipitate-matrix interface of coherent or semicoherent precipitates. Superlattice dark field imaging depicts the distribution of twin-related and epitaxial silicides in these systems. {111} interfaces were found to be more prominent than {001} interfaces. Twin-related silicides were observed to cover more area on the substrate silicon than epitaxial silicides did. In situ annealing of nickel and cobalt thin films on silicon provides a unique means of investigation of the transformation from polycrystalline to epitaxial silicides. The NiSi2 transformation was found to be very rapid at 820°C, whereas the CoSi2 transformation appeared to be very sluggish. Furnace annealing confirmed that only a small fraction of CoSi2 transforms to epitaxial CoSi2 after annealing at 850°C for 4 h. Diffraction contrast analysis has been applied to interfacial dislocations of epitaxial NiSi2/Si and CoSi2/Si systems. The dislocations were found to be of edge type with 1 6 〈112〉 and 1 2 〈110〉 Burgers' vectors. The average spacings are close to their respective theoretically predicted values.
A large-scale study of the evolution of web pages

How fast does the Web change? Does most of the content remain unchanged once it has been authored, or are the documents continuously updated? Do pages change a little or a lot? Is the extent of change correlated to any other property of the page? All of these questions are of interest to those who mine the Web, including all the popular search engines, but few studies have been performed to date to answer them.One notable exception is a study by Cho and Garcia-Molina, who crawled a set of 720 000 pages on a daily basis over 4 months, and counted pages as having changed if their MD5 checksum changed. They found that 40% of all Web pages in their set changed within a week, and 23% of those pages that fell into the .com domain changed daily.This paper expands on Cho and Garcia-Molina's study, both in terms of coverage and in terms of sensitivity to change. We crawled a set of 150 836 209 HTML pages once every week, over a span of 11 weeks. For each page, we recorded a checksum of the page, and a feature vector of the words on the page, plus various other data such as the page length, the HTTP status code, etc. Moreover, we pseudorandomly selected 0.1% of all of our URLs, and saved the full text of each download of the corresponding pages.After completion of the crawl, we analyzed the degree of change of each page, and investigated which factors are correlated with change intensity. We found that the average degree of change varies widely across top-level domains, and that larger pages change more often and more severely than smaller ones.This paper describes the crawl and the data transformations we performed on the logs, and presents some statistical observations on the degree of change of different classes of pages.
THE IMPACT OF PSYCHOLOGICAL AND HUMAN CAPITAL ON WAGES

Historically, economists have taken the position that psychological capital is either unobservable or immeasurable; thus, heretofore, little evidence has been available on the contribution of psychological capital to wages. Using data drawn from two different waves of the National Longitudinal Survey of Youth, we offer evidence that psychological capital has both a direct effect—via self-esteem—and an indirect effect—through locus of control—on an individual's real wage. We find a person s wage is more sensitive to changes in self-esteem than to comparable alterations in human capital. Both relative wages and human capital contribute to self-esteem.
Electron Heating in Hot Accretion Flows

Local (shearing box) simulations of the nonlinear evolution of the magnetorotational instability in a collisionless plasma show that angular momentum transport by pressure anisotropy (p⊥ ≠ p∥, where the directions are defined with respect to the local magnetic field) is comparable to that due to the Maxwell and Reynolds stresses. Pressure anisotropy, which is effectively a large-scale viscosity, arises because of adiabatic invariants related to p⊥ and p∥ in a fluctuating magnetic field. In a collisionless plasma, the magnitude of the pressure anisotropy, and thus the viscosity, is determined by kinetic instabilities at the cyclotron frequency. Our simulations show that ~50% of the gravitational potential energy is directly converted into heat at large scales by the viscous stress (the remaining energy is lost to grid-scale numerical dissipation of kinetic and magnetic energy). We show that electrons receive a significant fraction [~(Te/Ti)1/2] of this dissipated energy. Employing this heating by an anisotropic viscous stress in one-dimensional models of radiatively inefficient accretion flows, we find that the radiative efficiency of the flow is greater than 0.5% for 10-4Edd. Thus, a low accretion rate, rather than just a low radiative efficiency, is necessary to explain the low luminosity of many accreting black holes. For Sgr A* in the Galactic center, our predicted radiative efficiencies imply an accretion rate of ≈3 × 10-8 M☉ yr-1 and an electron temperature of ≈3 × 1010 K at ≈10 Schwarzschild radii; the latter is consistent with the brightness temperature inferred from VLBI observations.
Evaluating inflation targeting based on the distribution of inflation and inflation volatility

Abstract In this paper the Financial Development Index (FDI) is used to rank 57 of the world's leading financial systems. Its calculation is based on the following 7 economic pillars: (1) Institutional environment, (2) Business environment, (3) Financial stability, (4) Banking financial services, (5) Non-banking financial services, (6) Financial markets, and (7) Financial access. Pillar (4) is constructed from bond markets, stock markets, foreign exchange markets, and derivative markets. Pillar (5) includes a country's IPO activity, namely the IPO market share, IPO proceeds amount, and IPOs share of world IPOs. The stock market index provides a short-term account of financial activities, whereas the FDI provides a long-term broader account of the financial structure and health of an economy. As the performance and success of a given monetary policy would less likely be judged on short-term dynamics, it seems sensible to use the annual FDI as one of several economic and country attributes in a policy evaluation of Inflation Targeting. The paper offers a potential outcomes analysis of the impact of inflation targeting on inflation and inflation volatility, and focuses on advanced economies that adopt ⿿inflation targeting⿿ as a formal monetary policy. In order to deal with the counterfactual question, namely what would be the inflation rate for an adopting country had it not adopted this policy, the paper offers a new matching technique that subsumes the traditional propensity scores methods as a special case. The paper has different proposals for assessing ⿿matching⿿ based on the whole distribution of any ⿿scores⿿. Additionally, the paper goes beyond the Average Treatment Effect (ATE) and examines the entire distribution of inflation and its ⿿variability⿿. It is found that the adoption of inflation targeting has helped lower inflation (not just the mean) for the targeting countries. However, it is shown that exact numerical quantification of this policy effect is as highly subjective as choosing ideal social welfare functions. The paper also finds no evidence of a larger gain for ⿿late adopters⿿ of inflation targeting. As for inflation variability, there is some robust evidence of small and often statistically insignificant reduction in variability due to targeting.
Air-Side Surface Wettability Effects on the Performance of Slit-Fin-and-Tube Heat Exchangers Operating Under Wet-Surface Conditions

A study of condensate retention and the attendant thermal-hydraulic effect associated with changes in air-side surface wettability is presented for a series of slit-fin-and-tube heat exchangers of identical geometry with controlled wettability covering a wide range of contact angles. An experiment in which the retained mass of air-side condensate was measured under dynamic conditions is described, and the results are analyzed using conventional thermal-hydraulic measurements of j and f. The data demonstrate that for the heat exchangers used in this study, the j factor is not strongly influenced by condensate retention, but the friction factor is significantly reduced for surfaces of increased wettability. Hydrophilic heat exchangers retain much less air-side condensate than do the hydrophobic heat exchangers, and the amount of retention is found to depend on the air-side Reynolds number (Re dh ) and the rate of latent heat transfer (Q l ). Based on an assumption of filmwise condensation, a new model for predicting the mass of retained condensate is described and compared with the steady-sate retention data. The model is successful in predicting retained condensate over a wide range of tested conditions. The potential of this new approach and possible refinements that will add engineering value are discussed.
Dynamic Threshold Schemes for Multi-Level Non-Volatile Memories

In non-volatile memories, reading stored data is typically done through the use of predetermined fixed thresholds. However, due to problems commonly affecting such memories, including voltage drift, overwriting, and inter-cell coupling, fixed threshold usage often results in significant asymmetric errors. To combat these problems, Zhou, Jiang, and Bruck recently introduced the notion of dynamic thresholds and applied them to the reading of binary sequences. In this paper, we explore the use of dynamic thresholds for multi-level cell (MLC) memories. We provide a general scheme to compute and apply dynamic thresholds and derive performance bounds. We show that the proposed scheme compares favorably with the optimal thresholding scheme. Finally, we develop limited-magnitude error-correcting codes tailored to take advantage of dynamic thresholds.
Effect of Magnetic Field on Thermal Conductivity and Energy Gap of Superconducting Films

We have measured the change in the thermal conductivity of superconducting tin, indium, and lead films upon application of a magnetic field in the plane of the film. These experiments were undertaken to explore the dependence of the energy gap upon magnetic field and to determine the thermodynamic order of the field-induced transition in films. Within the range of temperatures available to us ($0.35{T}_{c}$ to $0.65{T}_{c}$) the thermal conductivity of indium and tin films increases nearly as ${H}^{2}$. In films of thickness $d\ensuremath{\geqq}2800$ \AA{} the thermal conductivity jumps at ${H}_{c}$ to the normal state value, indicating a first-order phase transition in thin films, consistent with the Ginzburg-Landau (GL) theory. If the effect of a field upon the superconducting state can be adequately represented as a change of the ${\ensuremath{\epsilon}}_{0}$ of BCS, we may use the theory of Bardeen, Rickayzen, and Tewordt to compute ${\ensuremath{\epsilon}}_{0}(H)$ from our data. At $T=0.65{T}_{c}$ we find $\frac{{\ensuremath{\epsilon}}_{0}(H)}{{\ensuremath{\epsilon}}_{0}(H=0)}={[1\ensuremath{-}{(\frac{H}{{H}_{c}})}^{2}]}^{\frac{1}{2}}$ in agreement with the GL prediction. At $T=0.35{T}_{c}$ however, $\frac{{\ensuremath{\epsilon}}_{0}(H)}{{\ensuremath{\epsilon}}_{0}(0)}=1\ensuremath{-}{(\frac{H}{{H}_{c}})}^{2}$ provides a more satisfactory fit to our data. Orientation of the field \ensuremath{\perp} and \ensuremath{\parallel} to the direction of heat flow produces the same effect on the thermal conductivity to \ifmmode\pm\else\textpm\fi{}1%. This is interesting in view of Bogoliubov's prediction of a ${\mathrm{p}}_{F}\ifmmode\cdot\else\textperiodcentered\fi{}{\mathrm{v}}_{\mathrm{drift}}$ term in the excitation spectrum of a current-carrying superconductor. When the field is not parallel to the surface of the film the thermodynamic transition is still sharply defined, but ${H}_{c}$ is reduced. Thin lead films gave results similar to those of indium and tin films except that at low fields the field-dependent conductivity increased more slowly than ${H}^{2}$ at low temperatures.
Angular motion of a spinning projectile with a viscous liquid payload

Abstract : Liquid payload motion can have a significant effect on the stability of a spinning projectile. A general definition of the liquid moment is developed and expressions are obtained for the frequencies and damping rates of the projectile's angular motion. An expression for the liquid pressure moment is derived without the unnecessary mathematical approximations of the Stewartson- Wedemeyer theory, and wall shear effects are added to this improved SW pressure moment to obtain the total liquid moment. This moment expression applies to cavities that are fully filled, partially filled or fully filled with a central rod. The improved theory shows that as the Reynolds number decreases, (a) the eigenfrequency-related side moment peaks decrease steadily in size but that (b) the average side moment level first increases and then decreases. This latter predicted behavior is in good qualitative agreement with the D'Amico-Miller conjecture that relates the liquid spin-down moment to the liquid side moment. Good agreement is also obtained between the theory and all available published data from liquid- filled gyroscope experiments.
Modeling the volume-effectiveness relationship in the case of hip fracture treatment in Finland

A common argument in the recent health policy debate is that treatment is more effective among care providers with large volumes. It is challenging, however, to examine the volume-effectiveness relationship empirically. Several suggestions have recently been made for methodological improvements in the examination of the volume-effectiveness relationship. The aim of this study is to develop an extended methodology for examining the volume-effectiveness relationship and demonstrate it for the case of hip fracture treatment. Data consisting of 22,857 hip fracture patients from 52 hospitals in Finland in 1998-2001 were extracted from the administrative registers. The relationship between hospital and rehabilitation unit volumes and effectiveness was examined using a statistical model that allowed risk adjustments and hierarchical modeling of volume trends, developed for the purposes of this study. Four-month mortality and the alternative register-based measure of maintainability were used as effectiveness indicators. No clear relationship was found between hospital volume and the effectiveness of hip fracture treatment, but a novel result showing an association between the rehabilitation unit volume and effectiveness was detected. The face validity of the maintainability indicator seemed to be acceptable. The methodological ideas presented allow for improved examination of the volume-effectiveness relationship. There are no indications that patients with hip fractures should only be treated in high-volume hospitals, though it may be beneficial to centralize the rehabilitation of hip fracture patients to specialized units.
A DIRECT IODINATION METHOD WITH IODINE AND SILVER TRIFLATE FOR THE SYNTHESIS OF SPECT AND PET IMAGING AGENT PRECURSORS

A direct iodination method with iodine and silver triflate for the synthesis of SPECT and PET imaging agent precursors has been developed.
Experiments on Supersonic Jet Noise

The noise generated by a 1-in. supersonic jet was investigated at nominal jet Mach numbers of 1.5, 2.0, and 2.5. In particular, a quantity W, referred to as the apparent source strength per unit length, was determined along the jet axis using a directional microphone system. The integrated value of W along the jet axis was found to agree with the sound intensity obtained by a conventional microphone. This result is consistent with the a priori assumption that the jet may be described in terms of independent, spatially compact acoustic sources. The main finding of the investigation is the discovery of two distinct intense noise-producing regions in a jet having supersonic source velocities: the upstream region associated with Mach wave radiation, and a zone, located downstream of the potential cone, exhibiting radiation similar in character to that of a subsonic jet. An estimate of the radiated intensity associated with the Mach waves also is made.
Characteristics of InAs ``dots-in-a-graded-well''

Abstract The influence of InAs growth rate and the group V–III beam equivalent pressure ratio on the optical and structural properties of InAs quantum dots in constant and graded composition (In,Ga)As quantum wells is investigated. Optimized growth conditions are found for both structures. It is suggested that the “dots-in-a-graded-well” structure might serve as a better active medium than the “dots-in-a-well” structure. Both structures are engineered to emit at the important telecommunication wavelength of 1.3 μm.
Remarks on the M5-brane

Abstract The fivebrane of M theory — the M5-brane — is an especially interesting object. It plays a central role in a geometric understanding of the Seiberg-Witten solution of N=2 D=4 gauge theories as well as in certain new 6d quantum theories. The low energy effective action is an interacting theory of a (2,0) tensor multiplet. The fact that this multiplet contains a two-form gauge field with a self-dual field strength poses special challenges. Recent progress in addressing those challenges is reviewed.
NNLO results for heavy quark and direct photon production near threshold

Abstract I present some results for the next-to-next-to-leading order expansions of the resummed cross sections for heavy quark and direct photon production near threshold in hadronic collisions.
Taut Foliations, Left-Orderability, and Cyclic Branched Covers

We study the question of when cyclic branched covers of knots admit taut foliations, have left-orderable fundamental groups, and are not L-spaces.