cssi/SciSciGPT-SciSciNet huggingface dataset:
Exterior/interior problem for the circular means transform with applications to intravascular imaging

Exterior inverse problem for the circular means transform (CMT) arises in the intravascular photoacoustic imaging (IVPA), in the intravascular ultrasound imaging (IVUS), as well as in radar and sonar. The reduction of the IPVA to the CMT is quite straightforward. As shown in the paper, in IVUS the circular means can be recovered from measurements by solving a certain Volterra integral equation. Thus, a tomography reconstruction in both modalities requires solving the exterior problem for the CMT. &nbsp Numerical solution of this problem usually is not attempted due to the presence of "invisible" wavefronts, which results in severe instability of the reconstruction. The novel inversion algorithm proposed in this paper yields a stable partial reconstruction: it reproduces the "visible" part of the image and blurs the "invisible" part. If the image contains little or no invisible wavefronts (as frequently happens in the IVPA and IVUS) the reconstruction is quantitatively accurate. The presented numerical simulations demonstrate the feasibility of tomography-like reconstruction in these modalities.
Energy Distribution of Neutral Mesons Produced in Cosmic-Ray Stars

A cloud-chamber study of the energy distribution of neutral mesons produced in cosmic-ray stars is reported. The cloud chamber contained a NaI scintillation crystal plate and was triggered when a nuclear interaction in the crystal caused a scintillation light pulse. Photons associated with nuclear interactions produced visible soft showers in passing through several lead plates placed below the crystal plate, and their energies are estimated from the sizes of these showers. It is concluded that the majority of photons associated with cosmic-ray stars arise from the usual mode of neutral meson decay, i.e., ${\ensuremath{\pi}}^{0}\ensuremath{\rightarrow}2\ensuremath{\gamma}$. The energy distribution (differential) of the neutral mesons is given as a power-law spectrum of exponent $\ensuremath{\nu}=\ensuremath{-}1.5\ifmmode\pm\else\textpm\fi{}0.2$ for ${\ensuremath{\pi}}^{0}$ energy between 400 and 900 Mev and $\ensuremath{\nu}=\ensuremath{-}2.7\ifmmode\pm\else\textpm\fi{}0.5$ for ${\ensuremath{\pi}}^{0}$ energy between 900 and 2000 Mev. The data are consistent with an extension of the power-law spectrum given above up to a ${\ensuremath{\pi}}^{0}$ energy of about 5000 Mev.
Trade and Migration in an Enlarged European Union: A Spatial Analysis

One of the most prominent features in the evolution of the European Union (EU) has been its geographical expansion. Using a dynamic general equilibrium approach, this paper predicts the effects of ...
Toward an integration of content and method in the science curriculum

Every curriculum designer operates under practical constraints, such as the student/teacher ratio, the amount of instruction time available, and the limitations of school budgets. Within these restricting boundaries he must maneuver so as to balance competing theoretical considerations, such as these: Can one encourage creative and critical thinking simultaneously? Should more time be spent on conveying the content of modern science or on the methods employed?
Synthesis of 3-arylmuconolactones using biphenyl metabolism in aspergillus

Abstract Strains of the fungus Aspergillus form 3-arylmuconolactones as secondary products of the metabolism of biphenyl and substituted biphenyls. The 3-arylmuconolactones are not found to support growth and can accumulate to significant concentrations. The metabolic pathway leading from hydroxylated biphenyls to lactones appears to proceed through 3,4-catechol intermediates.
Characterization of phenolic resins with thermogravimetry-mass spectrometry

Abstract As part of an advanced material research program, thermogravimetry-mass spectrometry (TG-MS) analysis of a phenolic resin was carried out recently for the study of the curing of the prepolymer, solvent extraction and carbonization of the polymer at high temperature in an inert atmosphere. These steps are critical to the quality of the produced advanced material. In addition to TG-MS, several other complementary techniques were also employed for the analysis of the phenolic resin prepolymer and its curing and thermal degradation products. These techniques include pyrolysis-gas chromatography-mass spectrometry, direct insertion probe-mass spectrometry and gas chromatography-mass spectrometry.
The Built Environment Predicts Observed Physical Activity

Background. In order to improve our understanding of the relationship between the built environment and physical activity, it is important to identify associations between specific geographic characteristics and physical activity behaviors.Purpose. Examine relationships between observed physical activity behavior and measures of the built environment collected on 291 street segments in Indianapolis and St. Louis. Methods. Street segments were selected using a stratified geographic sampling design to ensure representation of neighborhoods with different land use and socioeconomic characteristics. Characteristics of the built environment on street segments were audited using two methods: in-person field audits and audits based on interpretation of Google Street View imagery with each method blinded to results from the other. Segments were dichotomized as having a particular characteristic (e.g., sidewalk present or not) based on the two auditing methods separately. Counts of individuals engaged in different forms of physical activity on each segment were assessed using direct observation. Non-parametric statistics were used to compare counts of physically active individuals on each segment with built environment characteristic. Results. Counts of individuals engaged in physical activity were significantly higher on segments with mixed land use or all non-residential land use, and on segments with pedestrian infrastructure (e.g., crosswalks, sidewalks) and public transit. Conclusions. Several micro-level built environment characteristics are associated with physical activity. These data provide support for theories that suggest changing the built environment and related policies may encourage more physical activity.
Research on Neural Network PID Control Algorithm for a Quadrotor

Quadrotor is a kind of popular unmanned aerial vehicle which obtains prime advantages in simple structure, vertically taking off and landing and hovering ability; hence it possesses wide application prospects in reconnaissance and rescue, geological exploration and video surveillance. However, attitude and position control of the quadrotor are challenging tasks because it is an under-actuated system with strong nonlinear, coupling and model uncertainty characteristics. In this paper, the dynamics model and the state space function of the micro-quadrotor are firstly established. Then, a cascade control scheme is proposed to decouple the control system and a multivariate RBF(Radial Basis Function) neural network control PID algorithm is proposed to realize robust control of the quadrotor. This algorithm is not only characterized by simple structure and easy implementation, but also capable of self-adaption and online learning. Simulation results show that the proposed control algorithm performs well in tracking and under disturbances and model uncertainties.
Theories of Attitude Change and the “Beyond Family Planning” Debate: The Case for the Persuasion Approach in Population Policy

A descriptive review of various population policy strategies ranging from "do nothing" to "use inescapable force" contends that the potential efficacy of persuasive communication for inducing changes in family planning behavior have been underestimated. Six basic types of fertility programs are identified: 1) nonintervention 2) provision of information and supplies 3) persuasion 4) positive incentives 5) negative incentives and 6) inescapable force. The 2 most widely employed strategies are persuasion and positive incentives; the other methods are usually dismissed by policymakers as either ethically unacceptable ineffective or unfeasible. However there is increasing disillusionment with communication and persuasion among family planning practitioners and a growing willingness to consider situation-altering b ehavioristic strategies. This latter estimation is challenged by describing recent advances in attitude theory and measurement that may provide a useful set of guidelines for family planning communication programs. Nonetheless it is conceded that birth control communication programs may be ineffective in traditional societies until major social changes induced by universal education improved transportation and comm unication facilities increased agricultural and industrial output have broken the hard layer of custom.
A General, Enantioselective Synthesis of 1-Azabicyclo[m.n.0]alkane Ring Systems

In this Letter, we describe a novel approach for the general and enantioselective synthesis of a diverse array of small to large 1-azabicyclo[m.n.0]alkyl ring systems with an embedded olefin handle for further functionalization. The stereochemistry is established via a highly diastereoselective indium-mediated allylation of an Ellman sulfinimine in greater than 9:1 dr, which is readily separable by column chromatography to afford a single diastereomer. This methodology allows for the rapid preparation of 1-azabicyclo[m.n.0]alkane ring systems that are not readily accessible through any other chemistry in excellent overall yields and, for many systems, the only enantioselective preparation reported to date.
Ca ii H and K Chromospheric Emission Lines in Late‐K and M Dwarfs*

ABSTRACT We have measured the profiles of the Ca ii H and K chromospheric emission lines in 147 main‐sequence stars of spectral type M5–K7 (masses 0.30–0.55 M⊙) using multiple high‐resolution spectra obtained during 6 years with the HIRES spectrometer on the Keck I telescope. Remarkably, the average FWHM, equivalent widths, and line luminosities of Ca ii H and K increase by a factor of 3 with increasing stellar mass over this small range of stellar masses. We fit the Ca ii H and K lines with a double‐Gaussian model to represent both the chromospheric emission and the non‐LTE central absorption. Most of the sample stars display a central absorption that is typically redshifted by ∼0.1 km s−1 relative to the emission. This implies that the higher level, lower density chromospheric material has a smaller outward velocity (or higher inward velocity) by 0.1 km s−1 than the lower level material in the chromosphere, but the nature of this velocity gradient remains unknown. The FWHM of the Ca ii H and K emission ...
A system for the simultaneous delivery of intraoperative radiation and ultrasound hyperthermia

A multi-element ultrasonic applicator, utilizing an ultrasound reflector, is presented which enables the controlled delivery of ultrasonic energy for the induction of hyperthermia while allowing the simultaneous application of orthovoltage ionizing radiation. A temperature-controlled water circulating system allows for acoustic coupling, additional control over the tumour surface temperature and depth of maximum temperature into the tissue. In vim and in vivo testing supported the applicators objective of effectively controlling temperature elevation. Therapeutic target temperatures of 42°C can be achieved within a 5-min period and maintained for a 60-min treatment time. The depth of heat penetration could be varied as a function of surface temperature and ultrasound frequency. Heating was achieved to at least a depth of 3 cm. Radiation measurement methods verified the expected radiation dose uniformity and distribution.
OB associations and the nonuniversality of the cosmic abundances - Implications for cosmic rays and meteorites

The formation of the solar system inside an OB association is examined with particular attention to the elemental abundances which would have been ejected by the association's first few supernovae. It is found that the solar system material may have been significantly contaminated by these supernovae and thus the average interstellar composition may differ from the solar system composition. In particular, we find that many of the so-called isotopic and elemental abundance anomalies (e.g., Ne, C, O, s-process/r-process, etc.) found in meteoritic inclusions and in cosmic rays may be more representative of the average interstellar abundance. In other words, it may be that the average solar system abundances are what is 'anomalous'.
LISA sources in globular clusters

Globular clusters house a population of compact binaries that will be interesting gravitational wave sources for LISA. We provide estimates for the numbers of sources of several categories and discuss the sensitivity of LISA to detecting these sources. The estimated total number of detectable sources ranges from ~10 to ~103 with gravitational wave frequencies above 1 mHz. These sources are typically undetectable by any other means and thus offer an opportunity for doing true gravitational-wave astronomy. The detection of these sources would provide information about both binary star evolution and the dynamics of globular clusters.
Microphotography of shocks in crystals

Cameras and laser illuminators have been upgraded and combined into a coaxial streak and frame system. The argon laser illuminating the streak camera over the duration of the event is combined with the short pulsed dye laser for stop motion framing, using a polarization splitter. The combined beams are sent to the target, viewed by the same objective lens, then split by a second polarizing splitter and relayed to the appropriate cameras. A half-wave plate before the second splitter allows adjustable levels of light of each laser to be leaked to the opposite camera for fiducial purposes. A particular advantage of this arrangement is that both the laser beams are tailored and aimed separately. The dye laser is spatially filtered and focused to cover the frame. The argon laser is focused to a line on the target which is then imaged to the streak camera slit. The ability to see the focal line of the argon laser on the frame camera allows precise collocation of the fields of view of the two cameras.
Growth of the Greenland ice sheet: a performance assessment of altimeter retracking algorithms

The authors compare the performance of different altimeter retracking algorithms for measuring ice sheet elevations and growth rates. The results show that the threshold, ESA, and S/V retracking algorithms produce growth rates that are 30-55% smaller than those produced by the NASA algorithm. Based upon a comparison of crossover-point standard deviations, the analysis indicates that the surface elevation estimates produced by these algorithms are more repeatable than the NASA surface elevations. An analysis of the NASA algorithm shows that a mixing of its 5 and 9 parameter functional fits on the crossover-point altimeter waveforms occurs in over 70% of the crossover data. The mixing of the functional fits is shown to reduce the repeatability of the NASA elevations and this may be responsible for the larger estimates of ice sheet growth produced by the NASA retracking algorithm. The extremely close agreement between the standard deviations and the growth-rate estimates from the threshold, ESA, and S/V retracking algorithms: lead the authors to conclude that 0.10 m/yr is a more accurate estimate of the growth of the Greenland ice sheet from 1978-1987 (south of 72/spl deg/N). >
Pitting of Fe in pH 7.4 acetate buffer

Abstract The passivation and pitting of Fe in pH 7.4 acetate buffer solution has been investigated as a function of the acetate and chloride concentrations. The efficiency of passivation was found to depend on the concentrations of both solutes, with the highest efficiency in the more concentrated solutions. Cl− did not interfere with the establishment of passivity, either in potential sweep or potential step experiments, but was significantly less effective in promoting efficient passivation than acetate. Cl− only has a deleterious effect on passivation after the film has formed. Potentiostatic results obtained above the pitting potential in concentrated acetate solution suggest that the onset of pitting is associated with an interaction of the Cl− with a certain stage of development of the passive film, based on the similarity of results with those obtained previously in borate buffer solution. 1 M acetate acts as a more effective inhibitor for pitting than 0.2 M borate.
Analysis of sorting algorithms

By analyzing an algorithm, we mean to study the performance of an algorithm including the assertion of its correctness and a determination of the cost of its execution. Although a given algorithm is often analyzed in a particular way that is most suitable for such an algorithm, we are more interested in general procedures and techniques that can be used to study the performance of classes of algorithms. To be able to talk about general analysis techniques will not only add to our understanding of the behavior of a class of algorithms but will also, in many cases, lead to useful synthesis procedures. A good example illustrating these points is the various techniques that can be used to analyze a class of sorting algorithms which can be modelled as networks made up of comparator modules. In this paper, we discuss several approaches to such an analysis problem. Moreover, synthesis procedures suggested by these analysis techniques will also be presented.
An Object-Oriented Parallel Particle-in-Cell Code for Beam Dynamics Simulation in Linear Accelerators

We present an object-oriented three-dimensional parallel particle-in-cell (PIC) code for simulation of beam dynamics in linear accelerators (linacs). An important feature of this code is the use of split-operator methods to integrate single-particle magnetic optics techniques with parallel PIC techniques. By choosing a splitting scheme that separates the self-fields from the complicated externally applied fields, we are able to utilize a large step size and still retain high accuracy. The method employed is symplectic and can be generalized to arbitrarily high order accuracy if desired. A two-dimensional parallel domain decomposition approach is employed within a message-passing programming paradigm along with a dynamic load balancing scheme. Performance tests on an SGI/Cray T3E-900 and an SGI Origin 2000 show good scalability of the object-oriented code. We present, as an example, a simulation of high current beam transport in the accelerator production of tritium (APT) linac design.
On the strength of solid acids

The objective of the present work was to establish the relative strengths of some common solid acids and to put them on a scale familiar to chemists. A modified spectrophotometric approach involving Ho and HR indicators was developed. The red-shifts of spectra from the adsorbed neutral forms of 4-nitrotoluene and 4-nitrofluorobenzene were used to deduce the equivalent H2S04 concentrations. Thus, values of 70 to 80%, and 90 to 98% H2S04 were determined for silica-alumina and HY preparations, respectively. HM preparations were found to be mild superacids (stronger than 100% H2S04). On the other hand, H2S04/ZrO2 preparations had surface acidities about equivalent to 100% H2S04, and SbF5/silica-alumina was a superacid with − 14.5 < H0 < − 13.7. These data were correlated with the catalytic activities of the solid acids expressed either as In (reaction rate) at 370°C or as the temperature required to obtain 0.5% conversion of isobutane. The extent and nature of the secondary reactions also varied with the acidity. These results demonstrate that the intensive factor of the acidity (acid strength) dominated over the extensive factor (surface concentration of Bronsted sites) in controlling the acidity, and therefore the catalytic properties, of these solids.
Dynamic correlation length scales under isochronal conditions.

The origin of the dramatic changes in the behavior of liquids as they approach their vitreous state—increases of many orders of magnitude in dynamic time scales and transport properties—is a major unsolved problem in condensed matter. These changes are accompanied by greater dynamic heterogeneity, which refers to both spatial variation and spatial correlation of molecular mobilities. The question is whether the changing dynamics are coupled to this heterogeneity; that is, does the latter cause the former? To address this, we carried out the first nonlinear dielectric experiments at elevated hydrostatic pressures on two liquids, to measure the third-order harmonic component of their susceptibilities. We extract from this the number of dynamically correlated molecules for various state points and find that the dynamic correlation volume for non-associated liquids depends primarily on the relaxation time, sensibly independent of temperature and pressure. We support this result by molecular dynamic simulations showing that the maximum in the four-point dynamic susceptibility of density fluctuations is essentially invariant along isochrones for molecules that do not form hydrogen bonds. Our findings are consistent with dynamic cooperativity serving as the principal control parameter for the slowing down of molecular motions in supercooled materials.
Employer search and worker-firm match quality

Abstract Labor economists are devoting increasing attention to employer search. The existing literature falls into two categories: research on information networks and research on search effort. The empirical research on search effort considers the determinants of effort but does not attempt to measure its effectiveness. Other research considers the impact of information networks on labor market outcomes, but ignores the role of search effort. Using data from the Employment Opportunities Pilot Project (EOPP), this paper attempts to synthesize the empirical research on employer search effort by considering information networks and search effort together within a job-matching framework. Specifically, the effects of employer search on employee turnover are examined using both hazard models and Probit analysis. The effect of employer search on wage growth within the job is also considered. I find, consistent with prior research, that when firms search through informal networks, the resulting worker-firm matches are superior to those resulting from search through formal networks. I also find that the impact of employer search effort depends upon the type of information network used in the search process.
Thermoacoustic boundary layers near the liquid-vapor critical point.

We measure and calculate the sound attenuation within thermoacoustic boundary layers between solid surfaces and xenon at its critical density as the reduced temperature approaches zero. ( is the critical temperature.) Using the known thermophysical properties of xenon, we predict that the attenuation at the boundary first increases approximately as and then saturates when the effusivity of the xenon exceeds that of the solid. [The effusivity is , where is the isobaric specific heat and is the thermal conductivity.] The model correctly predicts the quality factors of resonances measured in a stainless steel resonator ; it also predicts the observed increase of the , by up to a factor of 8, when the resonator is coated with a polymer . The test data span the frequency range and the reduced temperature range . We also predict that the thickness of the thermal boundary layer in the xenon decreases approximately as until . ( is the bulk viscosity, is the heat capacity ratio, and is the speed of sound.) Still closer to , becomes complex and its magnitude increases. These predictions concerning have not yet been tested. We deduce accurate values for the heat capacity and thermal conductivity for xenon in the range .
Momentum projection of solitons including quantum corrections

The method of projection is applied to a relativistic field theory of fermions interacting with a nonlinear scalar field, specifically the Friedberg-Lee soliton model. Projection is effected by operating on a localized “bag” state with the translation operator exp (iP·Z), and integrating overZ. The resulting state is an eigenstate of zero momentum. The energy and the expectation value of other physical operators can be expressed as Gaussian moments of the Hamiltonian or the physical operator times powers of the momentum operator taken with respect to the bag state. Renormalization in the one-loop approximation is discussed in detail for the boson sector, and briefly for the fermion sector. The method can be tested for convergence against nonexpansion techniques. The latter, however, cannot so easily handle distortion of the Bose modes or the distortion of the Dirac sea.
Enantioselective and regioselective indium(III)-catalyzed addition of pyrroles to isatins.

The indium(III)-catalyzed enantioselective and regioselective addition of pyrroles to isatins is described. The effects of metal and solvent on the reactivity and selectivity are compared and discussed, demonstrating that the indium(III)–indapybox complex provides the most effective catalyst. A case of divergent reactivity between pyrroles and indoles is presented.
SYMPLECTIC NO-CORE SHELL MODEL

The symplectic no-core shell model (Sp-NCSM) is described. The theory is applied to a study of the structure of 12C and 16O. Results from a full 6ħΩ NCSM calculation for low-lying states in these nuclei using a realistic nucleon-nucleon interaction are found to project at approximately the 90% level onto a few of the leading 0p-0h and 2p-2h symplectic representations. The results are nearly independent of the oscillator strength parameter and whether bare or renormalized effective interactions are used in the analysis. The Sp-NCSM model space is typically only a very small fraction (under 1%) of the NCSM space, and grows slowly with increasing ħΩ. The comparisons with NCSM results suggest either the effective nucleon-nucleon interaction possesses a heretofore unappreciated symmetry, namely Sp(3,R) and the complementary (spin-isospin) supermultiplet symmetry, or the nuclear many-body system acts as a filter that allows the symplectic symmetry to propagate in a coherent way into the many-body dynamics while tending to dampen out symplectic symmetry breaking terms. Also, since the Sp-NCSM is a multi-ħΩ generalization of the Elliott SU(3) model, the results obtained to date reaffirm the relevance of SU(3) to atomic nuclei.
Alignment and Orientation Effects in Sr Energy Pooling

then the total energy transfer cross section for a particular initial state alignment can be expressed as a sum of the so-called fundamental cross sections, Um1m2 and Um1m2;m1′m2′, that describe collisions between the various mj states. Here Um1m2 represents the cross section for energy transfer when an atom in state m1 collides with an atom in state m2. The cross section Um1m2;m1′m2′ represents the contribution to the total cross section from interference when the colliding system is in a superposition of the state m1 colliding with m2 and the state m1′ colliding with m2′. It is found that the cross sections U1-1, U00, and U10 as well as the interference terms Re(U00;1-1) and U01;10 have relatively large values while U11 and U1-1;-11 are small. Coupled with future theoretical work, these results may provide new insights into the dynamics of the curve crossings that lead to energy transfer.
O+ transport across the polar cap

Abstract The plasma sheet, inner magnetosphere, and high-latitude magnetosphere all contain significant amounts of O + ions during active times. Singly charged oxygen ions unambiguously come from the ionosphere, making them an excellent tracer species. We test the cleft ion fountain theory, which asserts that O + ions escape from the cleft, cross the polar cap, and then enter the plasma sheet. Statistical studies of O + density in the cleft, high-altitude polar cap, and plasma sheet all indicate that the O + density increases with increasing solar wind dynamic pressure. In order to examine O + transport more directly, we use polar cap ion outflow measurements and the 2001 Tsyganenko magnetic field model driven with advanced composition explorer (ACE) solar wind parameters. We calculate the distance between the cleft and the ionospheric footpoints of magnetic field lines mapped from the polar spacecraft along the noon–midnight meridian. Using the observed outflow speed and the magnetic field line length we calculate the travel time for the ions. When we examine the distance from the cleft versus the O + travel time for individual passes, the slope of the line is consistent with the measured ionospheric convection speed across the polar cap. We conclude that O + ions emanating principally from the cleft are transported across the polar cap, and these O + ions have access to the ring current and plasma sheet.
Absence of Fragmentation in Two-Dimensional Bose-Einstein Condensation

We investigate the possibility that the BEC-like phenomena recently detected on two-dimensional finite trapped systems consist of fragmented condensates. We derive and diagonalize the one-body density matrix of a two-dimensional isotropically trapped Bose gas at finite temperature. For the ideal gas, the procedure reproduces the exact harmonic-oscillator eigenfunctions and the Bose distribution. We use a new collocation-minimization method to study the interacting gas in the Hartree-Fock approximation and obtain a ground-state wavefunction and condensate fraction consistent with those obtained by other methods. The populations of the next few eigenstates increase at the expense of the ground state but continue to be negligible; this supports the conclusion that two-dimensional BEC is into a single state.
MOMENTS OF SPIN STRUCTURE FUNCTIONS: SUM RULES AND POLARIZABILITIES

Received received date Revised revised date Nucleon structure study is one of the most important research areas in modern physics and has challenged us for decades. Spin has played an essential role and often brought surprises and puzzles to the investigation of the nucleon structure and the strong interaction. New experimental data on nucleon spin structure at low to intermediate momentum transfers combined with existing high momentum transfer data offer a comprehensive picture in the strong region of the interaction and of the transition region from the strong to the asymptotic-free region. Insight for some aspects of the theory for the strong interaction, Quantum Chromodynamics (QCD), is gained by exploring lower moments of spin structure functions and their corresponding sum rules (i.e. the Bjorken, BurkhardtCottingham, Gerasimov-Drell-Hearn (GDH), and the generalized GDH). These moments are expressed in terms of an operator-product expansion using quark and gluon degrees of freedom at moderately large momentum transfers. The higher-twist contributions have been examined through the evolution of these moments as the momentum transfer varies from higher to lower values. Furthermore, QCD-inspired low-energy effective theories, which explicitly include chiral symmetry breaking, are tested at low momentum transfers. The validity of these theories is further examined as the momentum transfer increases to moderate values. It is found that chiral perturbation theory calculations agree reasonably well with the first moment of the spin structure function g1 at low momentum transfer of 0.05 - 0.1 GeV2 but fail to reproduce some of the higher mo
Proton-pump Inhibitor Use Is Associated With Low Serum Magnesium Concentrations

Although case reports link proton-pump inhibitor (PPI) use and hypomagnesemia, no large-scale studies have been conducted. Here we examined the serum magnesium concentration and the likelihood of hypomagnesemia (
THE EFFECTS OF HIGH SCHOOL ATHLETIC PARTICIPATION ON EDUCATION AND LABOR MARKET OUTCOMES

We introduce a simple allocation-of-time model to explain the high school athletic participation choice and the implications of this choice for educational and labor market outcomes. Four different factors that could explain athletic participation are identified in the context of this model. A variety of tests of the model are provided using two data sets: the National Longitudinal Survey of Youth and the National Longitudinal Study of the High School Class of 1972. We find some evidence that athletic participation directly affects wages and educational attainment. However, much of the effect of athletic participation on wages and educational attainment appears to reflect differences across individuals in ability or value of leisure.
Constrained-realization Monte-Carlo method for hypothesis testing

Abstract We compare two theoretically distinct approaches to generate artificial (or “surrogate”) data for testing hypotheses about a given data set. The first and more straightforward approach is to fit a single “best” model to the original data, and then to generate surrogate data sets that are “typical realizations” of that model. The second approach concentrates not on the model but directly on the original data; it attempts to constrain the surrogate data sets so that they exactly agree with the original data for a specified set of sample statistics. Examples of these two approaches are provided for two simple cases; a test for deviations from a gaussian distribution, and a test for serial dependence in a time series. Additionally, we consider test for nonlinearity in time series based on a Fourier transform (FT) method and on more conventional autoregressive moving-average (ARMA) fits to the data. The comparative performance of hypothesis testing schemes based on these two approaches is found to depend on whether or not the discriminating statistic is pivotal. A statistic is “pivotal” if its distribution is the same for all processes consistent with the null hypothesis. The typical-realization method requires that the discriminating statistic satisfy this property. The constrained-realization approach, on the other hand, does not share this requirement, and can provide an accurate and powerful test without having to sacrifice flexibility in the choice of discriminating statistic.
Synthesis of 1-Azabenzanthracene: Epimerization with the Use of 1,3-Dihydrobenzo(c)thiophene -S,S Dioxide as a Source of ortho-Quinodimethane

Abstract The cycloaddition of o-quinodimethane, from 1,3-dihydrobenzo(c)-S,S dioxide, to 5,6-dihydroquinoline yields a mixture of adducts isomeric at the newly created ring junction. The cycloadducts can be dehydrogenated to the fully aromatic 1-azabenzanthracene.
Comparison of the Effects of Debonds and Voids in Adhesive Joints

An analytical model is developed to compare the effects of voids and debonds on the interfacial shear stresses between the adherends and the adhesive in simple lap joints. Since the adhesive material above the debond may undergo some extension (either due to applied load or thermal expansion or both), a modified shear lag model, where the adhesive can take on extensional as well as shear deformation, is used in the analysis. The adherends take on only axial loads and act as membranes. Two coupled nondimensional differential equations are derived, and in general, five parameters govern the stress distribution in the overlap region. As expected, the major differences between the debond and the void occur for the stresses near the edge of the defect itself. Whether the defect is a debond or a void, is hardly discernible by the stresses at the overlap ends for central defect sizes up to the order of 70 percent of the overlap region. If the defect occurs precisely at or very close to either end of the overlap, however, differences of the order of 20 percent in the peak stresses can be obtained.
FORMULATING AND ESTIMATING DYNAMIC LINEAR RATIONAL EXPECTATIONS MODELS

Abstract This paper describes methods for conveniently formulating and estimating dynamic linear econometric models under the hypothesis of rational expectations. An econometrically convenient formula for the cross-equation rational expectations restrictions is derived. Models of error terms and the role of the concept of Granger causality in formulating rational expectations models are both discussed. Tests of the hypothesis of strict econometric exogeneity along the lines of Sims's are compared with a test that is related to Wu's.
TOPTMH: TOPOLOGY PREDICTOR FOR TRANSMEMBRANE α-HELICES

Alpha-helical transmembrane proteins mediate many key biological processes and represent 20%–30% of all genes in many organisms. Due to the difficulties in experimentally determining their high-resolution 3D structure, computational methods to predict the location and orientation of transmembrane helix segments using sequence information are essential. We present TOPTMH, a new transmembrane helix topology prediction method that combines support vector machines, hidden Markov models, and a widely used rule-based scheme. The contribution of this work is the development of a prediction approach that first uses a binary SVM classifier to predict the helix residues and then it employs a pair of HMM models that incorporate the SVM predictions and hydropathy-based features to identify the entire transmembrane helix segments by capturing the structural characteristics of these proteins. TOPTMH outperforms state-of-the-art prediction methods and achieves the best performance on an independent static benchmark.
Quantitative analysis of blue noise mask generation

The blue noise mask (BNM) is a stochastic screen that produces visually pleasing blue noise. In its construction, a filter is applied to a given dot pattern to identify clumps in order to add or remove dots and thereby generate a correlated binary pattern for the next level. But up to now, all the filters were selected on a qualitative basis. There is no reported work describing precisely how the filtering and selection of dots affects the perceived error of the binary pattern. In this paper, we give a strict mathematical analysis of the BNM construction based on a human visual model, which provides insights to the filtering process and also prescribes the locations of the dots that will result in a binary pattern of minimum perceived error when swapped. The analysis also resolves some unexplained issues noticed by other researchers.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Adaptive simulation of boiler unit performance

Abstract Industrial boilers of a particular type will behave differently due to manufacturing or assembly tolerances. In addition, the performance of a boiler will vary at different times of its service life. The objective of the present study is to simulate a boiler unit. In the boiler model, heat transfer in the combustion chamber is simulated by the zone method; heat transfer in the secondary superheater, the reheater, the primary superheater, and the economizer is simulated by lump parameter analysis. One feature of the method used is that the models of the major components have been coupled sequentially according to the boiler configuration. Thus, it is assumed that this method may be applied to different boiler systems with different configurations. The uncertainty factors, such as water tube deposits, component deterioration and so on, are considered by modification factors which are determined from on-line measurements. Another feature of the boiler system simulation is that the major parts of the boiler system are simulated and coupled together to analyze some important operational parameters which impose a significant effect on boiler efficiency, such as main stream temperature, reheat temperature and reheat pressure drop. The boiler model has been tested and compared to on-line measurements data. The results are within a reasonable error range.
Planet X and the stability of resonances in the Neptune-Pluto system

Four test orbits of a trans-Plutonian planet have been integrated forward for four million years in order to determine the effects of such a body on the stability of the Neptune-Pluto 3:2 resonance. Planets beyond Pluto with masses of 0.1 M and 1.0 Earth masses in orbits at 48.3 and 75.5 AU, respectively, do not disturb the 3:2 resonance. Test planets of 5 Earth masses with semimajor axes of 52.5 and 62.5 AU disrupt the four million year libration of Pluto's argument of perihelion.
Large-Scale Live Active Learning: Training Object Detectors with Crawled Data and Crowds

Active learning and crowdsourcing are promising ways to efficiently build up training sets for object recognition, but thus far techniques are tested in artificially controlled settings. Typically the vision researcher has already determined the dataset's scope, the labels "actively" obtained are in fact already known, and/or the crowd-sourced collection process is iteratively fine-tuned. We present an approach for live learning of object detectors, in which the system autonomously refines its models by actively requesting crowd-sourced annotations on images crawled from the Web. To address the technical issues such a large-scale system entails, we introduce a novel part-based detector amenable to linear classifiers, and show how to identify its most uncertain instances in sub-linear time with a hashing-based solution. We demonstrate the approach with experiments of unprecedented scale and autonomy, and show it successfully improves the state-of-the-art for the most challenging objects in the PASCAL VOC benchmark. In addition, we show our detector competes well with popular nonlinear classifiers that are much more expensive to train.
A nonparametric model of term structure dynamics and the market price of interest rate risk

This article presents a technique for nonparametrically estimating continuous-time diffusion processes that are observed at discrete intervals. We illustrate the methodology by using daily three and six month Treasury Bill data, from January 1965 to July 1995, to estimate the drift and diffusion of the short rate, and the market price of interest rate risk. While the estimated diffusion is similar to that estimated by Chan, Karolyi, Longstaff, and Sanders (1992), there is evidence of substantial nonlinearity in the drift. This is close to zero for low and medium interest rates, but mean reversion increases sharply at higher interest rates. MODERN ASSET PRICING THEORY allows us to value and hedge a wide array of contingent claims, given a continuous-time model for the dynamics of the underlying state variables.1 Many such models have been developed to describe a range of economic variables, including stock prices (for pricing options and other derivatives) and real investment returns. Given the importance of valuing and hedging the huge institutional holdings of fixed income securities and derivatives, it is not surprising that one of the most common uses of continuous-time models has been in describing the dynamics of the short-term riskless interest rate, rt. Unfortunately, while the theory tells us what to do once we have a model for
An opportunistic global path planner

In this paper we describe a robot path-planning algorithm that constructs a global skeleton of free-space by incremental local methods. The curves of the skeleton are the loci of maxima of an artificial potential field that is directly proportional to distance of the robot from obstacles. Our method has the advantage of fast convergence of local methods in uncluttered environments, but it also has a deterministic and efficient method of escaping local extremal points of the potential function. We first describe a general roadmap algorithm, for configuration spaces of any dimension, and then describe specific applications of the algorithm for robots with two and three degrees of freedom.
The cost of equity in India: the effects of local and international models on equity pricing

This paper presents the first test of Indian-specific cost of equity measures: the capital asset pricing model (CAPM), global CAPM and an International Arbitrage Pricing Theory (IAPT) model. Using 312 firms weekly and 320 firms monthly derived from the Bombay Stock Exchange 500 Index, the firm tests the cost of equity under the three different models for both general Indian firms and Indian ADRs. This paper confirms the theory proposed by Stulz (1995), demonstrating that cost of equity is cheaper in global markets than in domestic markets. Both local CAPM and global CAPM conformed to theory, but IAPT results were highly irregular. This represents one of the largest and most recent studies of Indian equity capital and cost of equity model calculations to date. Significant differences in betas exist between the models. The results indicate that weekly data for the CAPM and global CAPM produce the most reliable equity calculations for Indian firms.
Reduced Adhesion of Staphylococcus aureus to ZnO/PVC Nanocomposites

In hospitals and clinics worldwide, medical device surfaces have become a rapidly growing source of nosocomial infections. In particular, patients requiring mechanical ventilation (and, thus, intubation with an endotracheal tube) for extended lengths of time are faced with a high probability of contracting ventilator-associated pneumonia. In this study, polyvinyl chloride (PVC) taken from a conventional endotracheal tube was embedded with varying concentrations of zinc oxide (ZnO) nanoparticles. Staphylococcus aureus biofilms were then grown on these nanocomposite surfaces during a 24-hour culture. Bacterial proliferation on the samples embedded with the highest concentration of ZnO nanoparticles was 87% less when compared to the control, indicating that this technique is effective at reducing biofilm formation on PVC surfaces without the use of antibiotics.
Fluorinated Nucleosides: Synthesis and Biological Implication

A number of important pharmaceuticals have been discovered and developed based on fluorinated analogs of biologically active nucleosides. The introduction of fluorine into a nucleoside structure at an appropriate position has modulated and/or improved the pharmacological properties of a molecule. The present review deals with the synthetic methodology, structural and biological implication of carbohydrate-modified fluoronucleosides.
Enantioselective Synthesis of β-(3-Hydroxypyrazol-1-yl) Ketones Using an Organocatalyzed Michael Addition Reaction

β-(3-Hydroxypyrazol-1-yl) ketones have been prepared in high yields and excellent enantioselectivities (94−98% ee) via a Michael addition reaction between 2-pyrazolin-5-ones and aliphatic acyclic α,β-unsaturated ketones using 9-epi-9-amino-9-deoxyquinine as the catalyst. These results account for the first example of an aza-Michael addition of the ambident 2-pyrazolin-5-one anion to a Michael acceptor.
Robust Control of a CSI-Fed Induction Motor Drive System

An application of modern control theory to the control of a current-source-inverter (CSI) fed induction motor drive system is presented. A linear quadratic Gaussian (LQG) control scheme is developed in which the Kalman filter is tuned for high robustness by a method of Doyle and Stein. The design is carried out for a sample system, and the robustness analysis and computer simulation results are included.
MODES OF INTERACTION BETWEEN DIVORCED PARENTS

I develop a model in which exact compliance with child support orders is synonymous with cooperative outcomes with respect to child good expenditures. The child support order imposed by institutional agents serves as focal point for the problem of dividing the gains from cooperation. Compliance is observed when the gains from cooperation exceed the value of noncooperation for both parents. The model is estimated using administrative data from the state of Wisconsin. My estimates imply that increasing child support enforcement activities may have weak effects on the welfare of children of divorced parents.