cssi/SciSciGPT-SciSciNet huggingface dataset:
Gastroesophageal reflux disease

Although gastroesophageal reflux disease (GERD) can be traced back to disorders of the gastroesophageal junction, stress and other relevant psychological factors can play an important role in the process of GERD. It would seem that, primarily, altered symptom perception based on threshold reduction exists in some patients. In an effort to describe the sensitisation for reflux symptoms, both central and peripheral factors can be discussed. The following is conceivable: that well defined personality factors moderate the effect of stress on the gastroesophageal junction, just as they can influence the perception and assessment of symptoms. Additionally, psychiatric disorders as comorbidities can also accompany GERD. For this reason, it is necessary to consider if an extension of hitherto psychological interventions could be helpful in patients with a subjective link between reflux and stress on an emotional personality related level, or in patients with attendant psychiatric disorders. This broadening relates both to the conservative use of antireflux medication and to surgical therapy, since a postoperative shift in symptoms can occur. The effectiveness of psychological interventions in several gastrointestinal patient groups could already be shown in the past, whereas evidence for their effectiveness in patients suffering with GERD is partly still outstanding and should be investigated in the future especially as several individual promising starts have been made.
Invariants of links in thickened surfaces

A group invariant for links in thickened closed orientable surfaces is studied. Associated polynomial invariants are dened. The group
Clustering and feature selection using sparse principal component analysis

In this paper, we study the application of sparse principal component analysis (PCA) to clustering and feature selection problems. Sparse PCA seeks sparse factors, or linear combinations of the data variables, explaining a maximum amount of variance in the data while having only a limited number of nonzero coefficients. PCA is often used as a simple clustering technique and sparse factors allow us here to interpret the clusters in terms of a reduced set of variables. We begin with a brief introduction and motivation on sparse PCA and detail our implementation of the algorithm in d’Aspremont et al. (SIAM Rev. 49(3):434–448, 2007). We then apply these results to some classic clustering and feature selection problems arising in biology.
Mechanisms of macromolecular protease inhibitors.

Proteolytic enzymes are ubiquitous in all organisms and constitute 2–4% of the encoded gene products. They are critical for diverse biological processes such as digestion, blood clotting, host defense, pathogenic infection, viral replication, wound healing, and disease progression, to name a few. Because proteases trigger an irreversible event - the cleavage of a protein - their activity must be tightly controlled. Dysregulated proteolytic activity causes a disruption in the homeostatic balance of a biological system and can result in any number of poor biological outcomes. As a result, nature has developed a number of strategies to control proteolysis, including spatial and temporal regulation, zymogen activation and protease degradation, and through the inhibition of proteases by macromolecular inhibitors. Somewhat surprisingly, relatively few design principles underlie the mechanisms of inhibition of a myriad range of macromolecular protease inhibitors. Significant engineering efforts have gone into modifying and improving inhibitor potency and specificity, and to a large extent, the same design principles that work well for naturally occurring protease inhibitors have proved valuable for inhibitors developed in the laboratory. This review aims to survey the mechanisms by which macromolecular protease inhibitors function. To do this, inhibitors have been divided into categories based on their mechanism in order to illustrate that a relatively small number of design principles can be combined to develop new and effective protease inhibitors. These divisions are not strict, and many inhibitors could be grouped in a number of classes. The list of mechanisms presented here is not exhaustive in its treatment of all inhibitors, but aims to be illustrative of the many ways proteases can be inhibited. For more information on genome-wide protease mining,[1] protease mechanism,[2] pre-clinical inhibition,[3] and drug discovery efforts,[4] the reader is directed to excellent reviews that have been written in recent years. Figure 1 provides an overview of basic substrate and protease nomenclature that will be used in this review. Open in a separate window Figure 1 (A) Diagram of a protease active site. A protease cleaves a peptide at the scissile bond, and has a number of specificity subsites, which determine protease specificity. Substrates bind to a protease with their non-prime residues on the N-terminal side of the scissile bond and their prime-side residues C-terminal to the scissile bond. The catalytic residues determine the class of protease. Serine, cysteine, and threonine proteases hydrolyze a peptide bond via a covalent acyl-enzyme intermediate, and aspartic, glutamic and metalloproteases activate a water molecule to hydrolyze the peptide bond in a non-covalent manner. (B) A serine protease (matriptase/MT-SP1, 1EAX.pdb) with the catalytic triad in yellow and the surface loops that surround the active site colored in blue. While the catalytic architecture of proteases is remarkably conserved, the surface loops are areas of high sequential and structural diversity.
Spin-current relaxation time in spin-polarized heisenberg paramagnets

We study the spatial Fourier transform of the spin correlation function Gq(L) in paramagnetic quantum crystals by direct simulation of a 1d lattice of atoms interacting via a nearest-neighbor Heisenberg exchange Hamiltonian. Since it is not practical to diagonalize the s = 1/2 exchange Hamiltonian for a lattice which is of sufficient size to study long-wavelength (hydrodynamic) fluctuations, we instead study the s → ∝ limit and treat each spin as a vector with a classical equation of motion. The simulations give a detailed picture of a the correlation function Gq(t) and its time derivatives. At high polarization, there seems to be a hierarchy of frequency scales: the local exchange frequency, a wavelength-independent relaxation rate 1/τ that vanishes at large polarization P → 1, and a wavelength-dependent spin-wave frequency ∝ q2. This suggests a form for the correlation function which modifies the spin diffusion coefficients obtained in a moments calculation by Cowan and Mullin, who used a standard Gaussian ansalz for the second derivative of the correlation function.
The Magnetization of Ferromagnetic Colloids

The magnetization curves of colloidal magnetite (${\mathrm{Fe}}_{3}$${\mathrm{O}}_{4}$) and colloidal siderac ($\ensuremath{\gamma}$-${\mathrm{Fe}}_{2}$${\mathrm{O}}_{3}$) have been determined by a null method for fields from 0 to 400 gauss. The measured curves have been found to agree with a theoretical curve based on the following assumptions: (1) Each colloid particle is a permanent magnet. This assumption is in accord with a prediction of the theory of ferromagnetism that small ferromagnetic particles be single magnetic domains. (2) There exists a distribution in the size of the particle moments similar to the weight distributions which have been found for other colloids. (3) The particles behave as the molecules of a classical paramagnetic gas. On this basis the average particle moment is found to be ${5.2(10)}^{\ensuremath{-}16}$ for the magnetite sol and ${7.4(10)}^{\ensuremath{-}16}$ for the siderac sol. Several other quantities related to the colloids are briefly discussed.
NEIGHBORHOOD INCOME DISTRIBUTIONS

This paper studies the distribution of income within neighborhoods and contrasts it with the national income distribution. It relies on a unique feature of the American Housing Survey, whose 1985, 1989 and 1993 waves of interviews provide data for small residential neighborhoods. These consist of a dwelling unit and up to ten of its nearest neighbors. Most previous work on neighborhoods has used information for much larger groupings of the population, such as census tracts. The paper employs a variety of parametric and nonparametric econometric tools to study income sorting across US residential neighborhoods. It documents the patterns of dependence among neighbors’ income and imperfect sorting, with moderate but very significant correlation among incomes of neighbors and of considerable income mixing in U.S. neighborhoods.
Sensor placement for on-orbit modal identification and correlation of large space structures

A method is presented for the selection of a set of sensor locations from a larger candidate set for the purpose of on-orbit identification and correlation of Large Space Structures. The method ranks the candidate sensor locations according to their contribution to the linear independence of the target modal partitions. In an iterative maner, the locations which do not contribute significantly are removed. The final sensor configuration tends to maximize determinant of the corresponding Fisher Information Matrix.
Fundamental limits of nonintrusive load monitoring

Provided an arbitrary nonintrusive load monitoring (NILM) algorithm, we seek bounds on the probability of distinguishing between scenarios, given an aggregate power consumption signal. We introduce a framework for studying a general NILM algorithm, and analyze the theory in the general case. Then, we specialize to the case where the error is Gaussian. In both cases, we are able to derive upper bounds on the probability of distinguishing scenarios. Finally, we apply the results to real data to derive bounds on the probability of distinguishing between scenarios as a function of the measurement noise, the sampling rate, and the device usage.
K-theory of toric varieties revisited

After surveying higher \(K\)-theory of toric varieties, we present Totaro’s old (c. 1997) unpublished result on expressing the corresponding homotopy theory via singular cohomology. It is a higher analog of the rational Chern character isomorphism for general toric schemes. In the special case of a projective simplicial toric scheme over a regular ring one obtains a rational isomorphism between the homotopy \(K\)-theory and the direct sum of \(m\) copies of the \(K\)-theory of the ground ring, \(m\) being the number of maximal cones in the underlying fan. Apart from its independent interest, in retrospect, Totaro’s observations motivated some (old) and complement several other (very recent) results. We conclude with a conjecture on the nil-groups of affine monoid rings, extending the nilpotence property. The conjecture holds true for \(K_0\).
Observation of Uniaxial Structures of Underpotentially Deposited Cadmium on Au(111) with in Situ Scanning Tunneling Microscopy

The atomic structures of several distinct adlayers of Cd underpotentially deposited onto a Au(111) surface in sulfuric acid electrolyte were revealed by in situ scanning tunneling microscopy (STM). Three ordered adlattices were observed, all of which have a long-range linear morphology rotated by 30° from the substrate's lattice directions. Complete geometric descriptions and proposed structures are presented for each. A purely electrostatic model is insufficient to explain the banded morphology which is observed; therefore, other structure-forming interactions, including lattice strain, are discussed as possible contributors.
Adverse Subpopulation Regression for Multivariate Outcomes with High-Dimensional Predictors

Biomedical studies have a common interest in assessing relationships between multiple related health outcomes and high-dimensional predictors. For example, in reproductive epidemiology, one may collect pregnancy outcomes such as length of gestation and birth weight and predictors such as single nucleotide polymorphisms in multiple candidate genes and environmental exposures. In such settings, there is a need for simple yet flexible methods for selecting true predictors of adverse health responses from a high-dimensional set of candidate predictors. To address this problem, one may either consider linear regression models for the continuous outcomes or convert these outcomes into binary indicators of adverse responses using pre-defined cutoffs. The former strategy has the disadvantage of often leading to a poorly fitting model that does not predict risk well, while the latter approach can be very sensitive to the cutoff choice. As a simple yet flexible alternative, we propose a method for adverse subpopulation regression (ASPR), which relies on a two component latent class model, with the dominant component corresponding to (presumed) healthy individuals and the risk of falling in the minority component characterized via a logistic regression. The logistic regression model is designed to accommodate high-dimensional predictors, as occur in studies with a large number of gene by environment interactions, through use of a flexible nonparametric multiple shrinkage approach. The Gibbs sampler is developed for posterior computation. The methods are evaluated using simulation studies and applied to a genetic epidemiology study of pregnancy outcomes.
A new continuation criterion for the relativistic Vlasov-Maxwell system

The global existence of solutions to the relativistic Vlasov–Maxwell system given sufficiently regular finite energy initial data is a longstanding open problem. The main result of Glassey and Strauss (Arch Ration Mech Anal 92:59–90, 1986) shows that a solution (f, E, B) remains C 1 as long as the momentum support of f remains bounded. Alternate proofs were later given by Bouchut et al. (Arch Ration Mech Anal 170:1–15, 2003) and Klainerman and Staffilani (Commun Pure Appl Anal 1:103–125, 2002). We show that only the boundedness of the momentum support of f after projecting to any two dimensional plane is needed for (f, E, B) to remain C 1.
Towards usage-based impact metrics: first results from the mesur project.

Scholarly usage data holds the potential to be used as a tool to study the dynamics of scholarship in real time, and to form the basis for the definition of novel metrics of scholarly impact. However, the formal groundwork to reliably and validly exploit usage data is lacking, and the exact nature, meaning and applicability of usage-based metrics is poorly understood. The MESUR project funded by the Andrew W. Mellon Foundation constitutes a systematic effort to define, validate and cross-validate a range of usage-based metrics of scholarly impact. MESUR has collected nearly 1 billion usage events as well as all associated bibliographic and citation data from significant publishers, aggregators and institutional consortia to construct a large-scale usage data reference set. This paper describes some major challenges related to aggregating and processing usage data, and discusses preliminary results obtained from analyzing the MESUR reference data set. The results confirm the intrinsic value of scholarly usage data, and support the feasibility of reliable and valid usage-based metrics of scholarly impact.
A new hypothesis for the origin and redistribution of sulfates in the equatorial region of western Mars

[1] The formation of sulfates on Mars has been under debate since they were identified by several Mars missions starting from the 1970s. We propose that sulfates formed as evaporites in enclosed standing bodies of water in the Valles Marineris area following the early alteration of Martian basaltic crust, were then elevated by the Tharsis uplift, and transported together with rock materials to Meridiani Planum by periodic outbursts of water, where they were deposited as sediments. The proposed model comprehensively addresses all forms of sulfate occurrences near the equator in the western Martian hemisphere and relates it to physiographic processes (volcanic, tectonic and sedimentary) affecting the Martian surface.
Growth of large, late-stage planetesimals

The paper discusses planetesimals which may have been produced without perturbations by Venus and changes that can be made in Wetherill's model (1976) of growth of large planetisimals. The late stage of terrestrial planets' growth determined their thermal properties and petrology, impact records, and possibly the existence of the moon. A critical result of late-stage models is the size of the largest planetesimals that grew near, and later impacted, those that became full-size planets. The relation between the size of planetesimals and their relative velocities has been misinterpreted, and some models neglect the possible decrease in relative velocity as control is transferred from the largest to the second-largest body in an accretion zone. The size of the second-largest planetesimal in the earth's zone may range from 300 to 2500 km, with corresponding accretion times of 7 times 10 to the 6th and 10 to the 8th power, respectively.
Large sensitivity to freshwater forcing location in 8.2 ka simulations

The 8.2 ka event is a key test case for simulating the coupled climate response to changes in the Atlantic Meridional Overturning Circulation (AMOC). Recent advances in quantifying freshwater fluxes at 8.2 ka from the proxy record have improved the realism of the forcing magnitude in model simulations, yet this forcing is still generally applied in an unrealistic geographic manner, across most of the Labrador Sea rather than just along the Labrador coast. Previous simulations with eddy- resolving ocean models have come to conflicting conclusions regarding the ability of such a coastally confined flow to impact the AMOC. These simulations have also not incorporated full atmosphere models nor have they used the new meltwater forcing values for 8.2 ka. We use the Community Climate System Model, version 3, with an ocean model resolution only slightly coarser than that used in previous eddy-resolving simulations, to test the sensitivity to freshwater forcing location. When revised freshwater forcing is applied across the Labrador Sea, the AMOC is reduced by ~40% and climate anomalies compare well with proxy records of the 8.2 ka event in terms of magnitude and duration. When the forcing is added just along the Labrador coast, however, most meltwater joins the subtropical gyre and travels to the subtropics with minor impact to the AMOC (~10% decrease). It is likely that model biases in the placement of the North Atlantic Current remain an important limitation for correctly simulating the 8.2 ka event.
A Preliminary Analytical and Experimental Investigation of Helicopter Rotor Boundary Layers

A momentum-integral technique was developed to calculate the laminar boundary layer on rotating airfoils. This technique was applied to a flat plate and an NACA 0012 airfoil at zero lift under steady rotation. Chordwise and spanwise velocity profiles, wall shear stresses, and separation lines are presented and are found to compare favorably with previous calculations using a finite-difference technique. Experimental velocity data were obtained on a hover stand using dual sensor hot wire probes. Chordwise and spanwise boundary-layer profiles are presented for an NACA 0012 airfoil at zero lift. Similar profiles were observed at various rotor speeds by scaling the ^-coordinate. The experimental profiles were found to be "fuller" than those predicted by momentum-integral calculations.
Iterative Asymmetric Allylic Substitutions: syn‐ and anti‐1,2‐Diols through Catalyst Control

A copper-catalyzed asymmetric allylic boronation (AAB) gives access to syn- and anti-1,2-diols. The method facilitates an iterative strategy for the preparation of polyols, such as the fully differentiated L-ribo-tetrol and protected D-arabino-tetrol. P=protecting group.
Vertex algebras and mirror symmetry

Mirror Symmetry for Calabi–Yau hypersurfaces in toric varieties is by now well established. However, previous approaches to it did not uncover the underlying reason for mirror varieties to be mirror. We are able to calculate explicitly vertex algebras that correspond to holomorphic parts of A and B models of Calabi–Yau hypersurfaces and complete intersections in toric varieties. We establish the relation between these vertex algebras for mirror Calabi–Yau manifolds. This should eventually allow us to rewrite the whole story of toric Mirror Symmetry in the language of sheaves of vertex algebras. Our approach is purely algebraic and involves simple techniques from toric geometry and homological algebra, as well as some basic results of the theory of vertex algebras. Ideas of this paper may also be useful in other problems related to maps from curves to algebraic varieties. This paper could also be of interest to physicists, because it contains explicit description of holomorphic parts of A and B models of Calabi–Yau hypersurfaces and complete intersections in terms of free bosons and fermions.
Area comparison results for isotropic surfaces

Consider a 2-plane $P \subset \mathbb{C}^n$ and let $D$ be a bounded region in $P$ with a piecewise-smooth boundary. Let $I(D)$ be the infimum of areas of all piecewise-smooth isotropic surfaces in $\mathbb{C}^n$ with the same boundary as $D$. Then $I(D)= \lambda_P^n \cdot Area(D)$. If $P$ is not complex, $\lambda_P^n < \frac{3\pi}{2\sqrt{2}}$. For a complex plane $\mathbb{C} \subset \mathbb{C}^n$, $\lambda_{\mathbb{C}}^n \geq 2$, $\lambda_{\mathbb{C}}^2 \geq 3$ and also $\frac{3\pi^2}{2\sqrt{2}}$ is the area of an explicit Hamiltonian stationary isotropic Mobius band embedded in $\mathbb{C}^n$ whose boundary is a unit circle in $\mathbb{C}$. As a corollary, a compact surface $\Sigma$ (possibly with boundary) in a symplectic manifold can be approximated by isotropic surfaces of area $\leq \frac{3\pi}{2\sqrt{2}} Area(\Sigma)$. Another corollary is that a closed curve of length $l$ in $\mathbb{C}^n$ bounds an isotropic surface of area $\leq \frac{3l^2}{8\sqrt{2}}$. A related result is the following: consider $\mathbb{C}P^1 \subset \mathbb{C}P^n$ and let $D$ be a region in $\mathbb{C}P^1$. Let $I(D)$ be the infimum of areas of all isotropic surfaces in $\mathbb{C}P^n$ with the same boundary as $D$ representing the same relative homology class mod 2 as $D$. Then $ 2 \cdot Area(D) \leq I(D) \leq \lambda_{\mathbb{C}}^n \cdot Area(D)$. Moreover the first inequality becomes an equality for $D=\mathbb{C}P^1$.
The Failed Patient Self-Determination Act and Policy Alternatives for the Right to Die

The empirical evidence regarding the implementation and impact of the federal Patient Self-Determination Act is examined in this article. The Act was designed to increase the use of advance medical directives in light of the U.S. Supreme Court's Cruzan decision. Research shows that the law has had little effect and that the use of advance directives has scant relation to medical treatment and care. Various policy alternatives for the right to die are also examined. The authors conclude with an analysis of the likely impact of medical costs, fruitless treatment, and rationed health care on limiting life-prolonging treatment.
The GSFC EUV and X-ray spectroheliograph on OSO-7

The Goddard Space Flight Center instrument carried on the pointed section of the OSO-7 satellite is described. This instrument contains: An extreme ultraviolet spectroheliograph using glancing incidence optics of Wolter's Type II to focus the Sun's light on the entrance slit of a concave grating spectrometer; an auxiliary Hα system; two X-ray spectroheliographs using mechanical collimators for spatial resolution and Ross filters to isolate spectral bands of interest, and a flare polarimeter operating in the 15–40 keV X-ray region. These subsystems may be operated in a number of modes which, when combined with the spacecraft modes, give the instrument great flexibility for making solar observations. Representative results from each of the subsystems are presented.
Entanglement entropy for probe branes

We give a prescription for calculating the entanglement entropy in holographic probe brane systems by systematically taking the leading order backreaction of the probe brane into account. We find a simple compact double integral formula, which is insensitive to many details of the backreaction, most notably the internal space or the non-metric fields sourced by the probe. We validate our method by comparing to exact results in solvable toy models. We also determine the entanglement entropies for a sphere and a strip in the top-down D3/D7 and D3/D5 system. For the sphere the entanglement entropy has also been obtained by other methods and we find perfect agreement.
A simple Fourier transform-based reconstruction formula for photoacoustic computed tomography with a circular or spherical measurement geometry

Photoacoustic computed tomography (PACT), also known as optoacoustic tomography or thermoacoustic tomography, is an emerging biomedical imaging technique that combines optical absorption contrast with ultrasound detection principles. Recently, a novel analytic image reconstruction formula has been proposed that operates on a data function expressed in the temporal frequency and spatial domains. The validity the formula has been demonstrated for a two-dimensional (2D) circular measurement geometry. In this study, computer simulation studies are conducted to validate the reconstruction formula for a three-dimensional (3D) spherical measurement geometry. This formula provides new insights into how the spatial frequency components of the sought-after object function can be explicitly determined by the temporal frequency components of the data function measured with a 2D circular or 3D spherical measurement geometry in PACT. Comparing with existing Fourier transform-based reconstruction formulas, the reconstruction formula possesses a simple structure that requires no computation of series expansions or multi-dimensional interpolation in Fourier space.
On the thermal broadening of a quantum critical phase transition

Abstract The temperature dependence of an integer Quantum Hall effect transition is studied in a sample where the disorder is dominated by short-ranged potential scattering. At low temperatures the results are consistent with a (T/T0)κ scaling behaviour and at higher temperatures by a linear dependence similar to that reported previously in other material systems. It is shown that the linear behaviour results from thermal broadening produced by the Fermi–Dirac distribution function and that the temperature dependence over the whole range depends both on the scaling parameter T0 and the width of the Landau level.
Band gap of strained graphene nanoribbons

The band structures of strained graphene nanoribbons (GNRs) are examined using a tight-binding Hamiltonian that is directly related to the type and magnitude of strain. Compared to a two-dimensional graphene whose band gap remains close to zero even if a large strain is applied, the band gap of a graphene nanoribbon (GNR) is sensitive to both uniaxial and shear strains. The effect of strain on the electronic structure of a GNR depends strongly on its edge shape and structural indices. For an armchair GNR, a weak uniaxial strain changes the band gap in a linear fashion, whereas a large strain results in periodic oscillation of the band gap. On the other hand, shear strain always tends to reduce the band gap. For a zigzag GNR, the effect of strain is to change the spin polarization at the edges of GNR, and thereby modulate the band gap. A simple analytical model, which agrees with the numerical results, is proposed to interpret the response of the band gap to strain in armchair GNRs. Open image in new window
Authentication and integrity in outsourced databases

In the Outsourced Database (ODB) model, entities outsource their data management needs to a third-party service provider. Such a service provider offers mechanisms for its clients to create, store, update, and access (query) their databases. This work provides mechanisms to ensure data integrity and authenticity for outsourced databases. Specifically, this article provides mechanisms that assure the querier that the query results have not been tampered with and are authentic (with respect to the actual data owner). It investigates both the security and efficiency aspects of the problem and constructs several secure and practical schemes that facilitate the integrity and authenticity of query replies while incurring low computational and communication costs.
FORMATION OF THE GALAXY

Current ideas on the formation of the Galaxy are reviewed. Many of the observed characteristics of our Milky Way System are consistent with a scenario in which the Galaxy formed inside out, with the inner part of it evolving by rapid collapse of a single protogalaxy, while the outer halo was accreted over an extended period. A number of possible problems with this "Standard Model" are discussed and summarized in section 5.
C2-symmetric N,N′-bis(terpenyl)ethylenediamines—synthesis and application in the enantioselective nitroaldol reaction

Optically pure C2-symmetric chiral diamines, have been synthesized by the reaction of terpenylamines with diethyloxalate, followed by the reduction of diamide with BH3–BF3. The methodology has been successfully applied and high yields achieved in the synthesis of chiral diamines derived from terpenes such as α-pinene, β-pinene, and 2-iso- and 4-carenes. These chiral diamines are found to be to be highly effective in inducing chirality in the nitroaldol reaction.
Convoy electron production by heavy ions in solids

Abstract The term “convoy” electron refers to those electrons ejected in fast ion-atom and ion-solid collisions closely matched in vector velocity to that of the incident heavy particles responsible for their ejection. Similarities and differences among electrons ejected into such states through binary electron capture to continuum and electron loss to continuum processes in single ion-atom encounters are compared and contrasted to more complex ejection processes occurring in solid targets. Puzzles posed by the apparent strong projectile Z dependence but weak emergent ion charge dependence of the yield in the case of solid targets are reviewed. Very recent progress in resolving these puzzles has been made by recent observations that the apparent mean free path for electron scattering out of the forward direction within the target is observed to be an order of magnitude greater than that for free electrons of equal velocity provided the projectile charge is high.
Hydrothermal Synthesis of Vanadium Oxides

The use of mild hydrothermal methods to synthesize vanadium oxides is reviewed, with particular emphasis on those with layer and 3-dimensional structures. A wide range of studies has been performed predominantly in the past decade to grow new materials that might have interesting electrochemical and magnetic properties. Most emphasis has been placed on vanadium oxides that contain organic species or simple cations such as the alkali metals, alkaline earths, zinc and copper. The key parameters determining the structures formed are reviewed, including pH and the organic structure-directing ion. Some initial electrochemical studies are described.
Distribution of zeros of random and quantum chaotic sections of positive line bundles

We study the limit distribution of zeros of certain sequences of holomorphic sections of high powers M N of a positive holomorphic Hermitian line bundle L over a compact complex manifold M. Our first result concerns “random” sequences of sections. Using the natural probability measure on the space of sequences of orthonormal bases {S N j} of H 0(M, L N ), we show that for almost every sequence {S N j}, the associated sequence of zero currents &1/N Z S N j ; tends to the curvature form ω of L. Thus, the zeros of a sequence of sections s N ∈H 0(M, L N ) chosen independently and at random become uniformly distributed. Our second result concerns the zeros of quantum ergodic eigenfunctions, where the relevant orthonormal bases {S N j } of H 0(M, L N ) consist of eigensections of a quantum ergodic map. We show that also in this case the zeros become uniformly distributed.
Pressure-induced changes in the electronic structure of solids

Abstract A variety of high-pressure metallization and metal-semimetal transitions, crystallographic phase transitions, and equation of state and lattice vibrational anomalies are reviewed in terms of the concepts of electronic transition and pressure-induced loss of covalency.
Fixed exchange rates with escape clauses: The political determinants of the European Monetary System realignments

Abstract This paper studies the political economy of realignments to fixed exchange rates and suggests that the use of realignments is less likely when there are political benefits from stable exchange rates and when linkages across other issue areas increase the costs of realignment. More specifically for the case of the European Monetary System (EMS), the expectation is that realignments are related to partisanship, support for the broader European integration, trade integration, resource transfers from the European Community, as well as countries reacting to the political and economic costs of realignment in other EMS members. Hypotheses are tested using binomial logit models on monthly data on exchange rate realignments for all EMS countries from 1979 to 1993. I find lower realignment risk for left wing policy-makers and countries with more trade links to Germany, whereas more intra-European Community resource transfers appear to go to countries facing higher realignment risk. Also, realignments are less likely when the rest of EMS member countries have stable international reserves and their governments are pro-European.
Body Temperature Studies in Anesthetized Man: Effect of Environmental Temperature, Humidity, and Anesthesia System

The possibility of great harm occurring as a sequel to marked elevations of body temperature is well known. Heat retention (also called heat stroke or heat pyrexia) may be associated with convulsions, coma, and psychic disturbances in the recovery phase. 1 In fatal cases, generalized degeneration of the neurons of the central nervous system, centrolobular liver necrosis, lower nephron nephrosis, and widespread hemorrhages, especially in the lungs and subendocardial tissues, are found. 2 The similarity of the pathological lesions found in patients dying following fever therapy and those produced by anoxia from any cause has been stressed by Hartman 3 ; hypoxia occurs at the tissue level because of increased metabolic oxygen demand associated with fever, which cannot be met by the cardiorespiratory transport system. It has been suggested that liver cells in addition to the cells of the central nervous system are particularly susceptible to damage during high fever. 4
Topological Field Theories and Harrison Homology

Tools and arguments developed by Kevin Costello are adapted to families of “Outer Spaces” or spaces of graphs. This allows us to prove a version of Deligne’s conjecture: the Harrison homology associated with a homotopy commutative algebra is naturally a module over a cobordism category of 3-manifolds.
Portable Experimental Apparatus for Demonstrating Thermodynamics Principles

A refrigeration system for use as experimental apparatus was designed, developed and constructed. Its purpose was to demonstrate to mechanical engineering undergraduates the basic concepts of thermodynamics, such as the first and second laws. In addition, the apparatus demonstrates a vapor compression refrigeration cycle. This paper presents a set of experiments in which the first and second laws of thermodynamics are employed to determine the heat gained by the refrigerant in the evaporator, the heat rejected from the refrigerant in the condenser, and the isentropic efficiency of the compressor. The objective of these experiments is to help students understand the basic thermodynamics processes by utilizing real-life applications.
Preparation and use of 1-iodoalkyl ylides

Abstract α-Iodoalkyl ylides were prepared and used for first time to convert aldehydes to 2-iodo-2-alkenes stereoselectively and to other dialkyl vinyl iodides.
Jordan blocks and exponentially decaying higher-order Gamow states

In the framework of the rigged Hilbert space, unstable quantum systems associated with first-order poles of the analytically continued S-matrix can be described by Gamow vectors which are generalized vectors with exponential decay and a Breit-Wigner energy distribution. This mathematical formalism can be generalized to quasistationary systems associated with higher-order poles of the S-matrix, which leads to a set of Gamow vectors of higher order with a non-exponential time evolution. One can define a state operator from the set of higher-order Gamow vectors which obeys the exponential decay law. We shall discuss to what extent the requirement of an exponential time evolution determines the form of the state operator for a quasistationary microphysical system associated with a higher-order pole of the S-matrix.
Exploring the beta distribution in variable-density turbulent mixing

In assumed probability density function (PDF) methods of turbulent combustion, the shape of the scalar PDF is assumed a priori and the PDF is parametrized by its moments for which model equations are solved. In non-premixed flows the beta distribution has been a convenient choice to represent the mixture fraction in binary mixtures or a progress variable in combustion. Here the beta-PDF approach is extended to variable-density mixing: mixing between materials that have very large density differences and thus the scalar fields are active. As a consequence, new mixing phenomena arise due to (1) cubic nonlinearities in the Navier–Stokes equation, (2) additional nonlinearities in the molecular diffusion terms and (3) the appearance of the specific volume as a dynamical variable. The assumed beta-PDF approach is extended to transported PDF methods by giving the associated stochastic differential equation (SDE). This enables the direct computation of the scalar PDF in a Monte–Carlo fashion. Using the moment equ...
A STELLAR-MASS-DEPENDENT DROP IN PLANET OCCURRENCE RATES

The Kepler spacecraft has discovered a large number of planets with up to one-year periods and down to terrestrial sizes. While the majority of the target stars are main-sequence dwarfs of spectral type F, G, and K, Kepler covers stars with effective temperatures as low as 2500 K, which corresponds to M stars. These cooler stars allow characterization of small planets near the habitable zone, yet it is not clear if this population is representative of that around FGK stars. In this paper, we calculate the occurrence of planets around stars of different spectral types as a function of planet radius and distance from the star and show that they are significantly different from each other. We further identify two trends. First, the occurrence of Earth- to Neptune-sized planets (1-4 R ⊕) is successively higher toward later spectral types at all orbital periods probed by Kepler; planets around M stars occur twice as frequently as around G stars, and thrice as frequently as around F stars. Second, a drop in planet occurrence is evident at all spectral types inward of a ~10 day orbital period, with a plateau further out. By assigning to each spectral type a median stellar mass, we show that the distance from the star where this drop occurs is stellar mass dependent, and scales with semi-major axis as the cube root of stellar mass. By comparing different mechanisms of planet formation, trapping, and destruction, we find that this scaling best matches the location of the pre-main-sequence co-rotation radius, indicating efficient trapping of migrating planets or planetary building blocks close to the star. These results demonstrate the stellar-mass dependence of the planet population, both in terms of occurrence rate and of orbital distribution. The prominent stellar-mass dependence of the inner boundary of the planet population shows that the formation or migration of planets is sensitive to the stellar parameters.
Free radical chlorination and one-electron oxidation of arylcyclopropanes. Designer probes for cytochrome P-450 hydroxylation mechanisms

Abstract Arylcyclopropyl radicals can be formed under mild conditions (phase-transfer-catalyzed chlorination) and give rise to cyclopropyl products; in contrast one-electron oxidation of arylcyclopropanes by Mn(OAc) 3 leads to fragmentation of the cyclopropane ring and the formation of acyclic products.
The impact of soda taxes on consumer welfare: : implications of storability and taste heterogeneity

The typical analysis on the effectiveness of soda taxes relies on price elasticity estimates from static demand models, which ignores consumers' inventory behaviors and their persistent tastes. This article provides estimates of the relevant price elasticities based on a dynamic demand model that better addresses potential intertemporal substitution and unobservable persistent heterogeneous tastes. It finds that static analyses overestimate the long-run own-price elasticity of regular soda by 60.8%, leading to overestimated consumption reduction of sugar-sweetened soft drinks by up to 57.9% in some cases. Results indicate that soda taxes will raise revenue but are unlikely to substantially impact soda consumption.
A Stochastic Model for Wound Healing

We present a discrete stochastic model which represents many of the salient features of the biological process of wound healing. The model describes fronts of cells invading a wound. We have numerical results in one and two dimensions. In one dimension we can give analytic results for the front speed as a power series expansion in a parameter, p, that gives the relative size of proliferation and diffusion processes for the invading cells. In two dimensions the model becomes the Eden model for p ≈ 1. In both one and two dimensions for small p, front propagation for this model should approach that of the Fisher-Kolmogorov equation. However, as in other cases, this discrete model approaches Fisher-Kolmogorov behavior slowly.
Seasoned equity offerings: stock market liquidity and duration of the completion cycle

Purpose – Short‐term cash need plays a critical role in equity issuance decisions. Consequently, the ease with which a seasoned equity offer (SEO) is completed can have a direct effect on the cost of raising equity. The purpose of this paper is to examine whether liquidity is likely to affect the ease with which an offer is completed, as proxied by the length of the offer.Design/methodology/approach – This study uses multiple regression analysis to establish the link between liquidity and the duration of the SEO completion cycle. To provide support to the findings, event study methodology is employed to study the abnormal volume turnover during the pre‐SEO announcement period for firms with shorter and longer registration periods.Findings – The paper finds that firms with greater liquidity come to market sooner. The results indicate a small yet significant effect of liquidity on the duration of the SEO completion cycle. There is also evidence that lower pre‐announcement period volume turnover is associate...
Applications of Smooth Particle Hydrodynamics (SPH) to astrophysical problems

Abstract A brief review of astrophysical applications of the Smooth Particle Hydrodynamics method is presented. It is shown that SPH has been applied to a variety of problems usually beyond the capabilities of standard techniques. Two examples, mass exchanging white-dwarf binaries and colliding planets, illustrate that relatively sophisticated physics can easily be incorporated in the method.
Flow-Induced Vibrations of Pressure/Temperature Sensors

Flow-induced vibrations of sensors are traditionally predicted through use of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code Section III Appendix N-1300. For an Euler―Bernoulli beam, this code provides engineers with a dynamic response prediction for a given sensor―fluid environment. Engineers can use this information to estimate fatigue life of a particular probe design. However, this tool provides no estimation of shear stresses experienced by the sensor under fluid-structure interaction and can give very conservative results in some cases. Because shear stresses are significant, especially for a low aspect ratio, minimally intrusive sensors or those which vibrate with very high frequencies, shear stresses must be included in the response prediction method. This can be achieved by moving away from Euler―Bernoulli to Timoshenko beam models. Upon making this step, American Society of Mechanical Engineers guidelines must be modified to allow inclusion of shear stresses. A modification to the code is presented which includes not only shear stresses experienced by the sensor, but also the mean response. The use of elliptical sections in preference to circular sections is also explored.
A Potential Remote-Sensing Technique for Thermospheric Temperature with Ground-Based Resonant Atomic Oxygen Raman Lidar

Abstract We propose a remote-sensing technique to measure temperature in the lower thermosphere with a resonant Raman lidar. A ground-based pulsed laser operating at 630.0304 (636.3776) nm excites 3P2 (3P1) multiplet level of the ground electronic state of atomic oxygen in the atmosphere to the electronically excited 1D2 state and the back-scattered photons at 636.3776 (630.0304) nm, while the atom transitions to 3P1 (3P2), are detected. Using the backscattering Raman cross sections calculated here we show: (1) For the range of altitudes in the lower thermosphere where the fine-structure multiplets of atomic oxygen are in thermodynamic equilibrium with the local translational temperature (LTE) and the electronically excited intermediate state 1D2 remains relaxed primarily by collisions with N2 and O2, the ratio of the backscattered signal can be used to obtain temperature. (2) Higher up, for the range of altitudes where the fine-structure multiplets of atomic oxygen are in LTE and the electronically excited intermediate state 1D2 is relaxed primarily by spontaneous emission of a photon, the Stokes and anti-Stokes backscattered signal can be used to obtain the atomic oxygen density and local temperature. (3) Still higher up, for the range of altitudes where the fine-structure multiplets of atomic oxygen are not in LTE and the electronically excited intermediate state 1D2 is relaxed primarily by spontaneous emission of a photon, the Stokes and anti-Stokes backscattered signal can be used to obtain the density of the 3P2 and 3P1 multiplet levels of the ground electronic state of atomic oxygen. For a ground-based instrument a simulation with 3 km range gate is used to show that the relative error of temperature measurements from 100 to 250 km could be less than 30%. It is pointed out that this technique has the potential of providing unique data that addresses the modeling of satellite drag and the effects of space weather on the upper atmosphere. In addition, this technique may also permit the detection of the thickness of the temperature inversion layers as well as their temperature and density perturbations.
Experimental and Estimated Rate Constants for the Reactions of Hydroxyl Radicals with Several Halocarbons

Relative rate experiments are used to measure rate constants and temperature dependencies of the reactions of OH with CH3F (41), CH2FCl (31), CH2BrCl (30B1), CH2Br2 (3OB2), CHBr3 (2OB3), CF2BrCHFCl (123aBl(alpha)), and CF2ClCHCl2 (122). Rate constants for additional compounds of these types are estimated using an empirical rate constant estimation method which is based on measured rate constants for a wide range of halocarbons. The experimental data are combined with the estimated and previously reported rate constants to illustrate the effects of F, Cl, and Br substitution on OH rate constants for a series of 19 halomethanes and 25 haloethanes. Application of the estimation technique is further illustrated for some higher hydrofluorocarbons (HFCs), including CHF2CF2CF2CF2H (338pcc), CF3CHFCHFCF2CF3 (43-10mee), CF3CH2CH2CF3 (356ffa), CF3CH2CF2CH2CF3 (458mfcf), CF3CH2CHF2 (245fa), and CF3CH2CF2CH3 (365mfc). The predictions are compared with literature data for these compounds.