cssi/SciSciGPT-SciSciNet huggingface dataset:
Size-dependent piezoelectricity

Abstract In this paper, a consistent theory is developed for size-dependent piezoelectricity in dielectric solids. This theory shows that electric polarization can be generated as the result of coupling to the mean curvature tensor, unlike previous flexoelectric theories that postulate such couplings with other forms of curvature and more general strain gradient terms ignoring the possible couple-stresses. The present formulation represents an extension of recent work that establishes a consistent size-dependent theory for solid mechanics. Here by including scale-dependent measures in the energy equation, the general expressions for force- and couple-stresses, as well as electric displacement, are obtained. Next, the constitutive relations, the uniqueness theorem and the reciprocal theorem for the corresponding linear small deformation size-dependent piezoelectricity are developed. As with existing flexoelectric formulations, one finds that the piezoelectric effect can also exist in isotropic materials. However, in the present theory there is only one flexoelectric constant for isotropic material and the coupling is strictly through the skew-symmetric mean curvature tensor. In the last portion of the paper, this isotropic case is considered in detail by developing the corresponding boundary value problem for two dimensional analyses and obtaining a closed form solution for an isotropic dielectric cylinder.
Fast evaluation, weights and nonlinearity of rotation-symmetric functions

Abstract We study the nonlinearity and the weight of the rotation-symmetric ( RotS ) functions defined by Pieprzyk and Qu. We give exact results for the nonlinearity and weight of 2-degree RotS functions with the help of the semi-bent functions and we give the generating function for the weight of the 3-degree RotS function. Based on the numerical examples and our observations we state a conjecture on the nonlinearity and weight of the 3-degree RotS function.
Black hole horizons and the thermodynamics of strings

Abstract We review the classical thermodynamics and the greybody factors of general (rotating) non-extreme black holes and discuss universal features of their near-horizon geometry. We motivate a microscopic interpretation of general black holes that relates the thermodynamics of an effective string theory to the geometry of the black hole in the vicinity of both the outer and the inner event horizons. In this framework we interpret several near-extreme examples, the universal low-energy absorption cross-section, and the emission of higher partial waves from general black holes.
North‐south asymmetry in Martian crater slopes

[1] The presence of an extensive ice-rich layer in the near subsurface of the Martian regolith could result in viscous creep responsible for softening of craters at middle and high latitudes. The temperature of ground ice will vary spatially within a crater owing to the effect of slope on the effective angle of insolation. The temperature at a particular latitude will also vary temporally owing to changes in Mars' obliquity. Results from numerical simulations of viscous creep indicate that these temperature variations cause the pole-facing slopes of craters to be systematically steeper than those of equator-facing slopes. Crater slopes should be most asymmetric between 25° and 40° latitude, depending on the thickness of the creeping layer. This slope asymmetry predicted from theoretical simulations of regolith creep is not well developed in observed Martian crater topography. Mars Orbiter Laser Altimeter (MOLA) topography of craters 16 to 40 km in diameter was analyzed for north-south slope asymmetry within seven latitude regions ranging from 60°S to 60°N. On the basis of the lack of any systematic slope asymmetry observed in the craters, we can place a conservative upper limit of ∼150 m on the thickness of the ice-rich creeping layer assuming a volumetric dust content of ≤70% and an exponentially decreasing regolith porosity with depth. If the creeping layer contains relatively clean ice, then the thickness of ice-rich material is limited to ∼100 m or less. The observations also suggest that the thickness of this creeping layer is reduced by ∼30% toward the equator. These results imply a global ice-rich regolith water volume of <∼107 km3, comparable to that proposed for a modest-sized northern plains ocean.
The cleavage of two carbon-carbon bonds in a Wolff-Kishner reduction

Abstract The reaction of dispiro[cyclopropane-1,1′-indan-3′,1″-cyclopropane]-2′-one (1) under Wolff-Kishner conditions gives spiro[cyclopropane-1,1′-indan] (2) in which the ketone has been reduced and two bonds of one cyclopropane ring have been cleaved.
Ru3Sn7 with the Ir3Ge7 structure-type

Abstract Millimeter-sized single crystals of the title compound have been grown from a Sn-rich melt and neutron diffraction data recorded at room temperature and 20 K have been used to confirm and refine the crystal structure. The Ir3Ge7 structure-type, cubic Im 3 m can be viewed as a framework of alternating corner linked Ru6Sn8 capped-octahedral clusters and Ru2Sn4 flattened-octahedral clusters, such that the latter form their own three-dimensional sublattice. The Ru–Sn distances determined for Ru3Sn7 fall in the middle of the observed range tabulated from the handful of known Ru–Sn distances in intermetallics. The resistivity of Ru3Sn7 is metallic, with a value of 72 μΩ cm at 300 K and 0.5 μΩ cm at 5 K. The magnetic susceptibility is diamagnetic at room temperature, but becomes paramagnetic as the temperature is lowered. We interpret the susceptibility as being due to a diamagnetic `core' contribution and a paramagnetic contribution arising from the Ru d orbitals.
Large-x parton distributions

Abstract Reliable knowledge of parton distributions at large x is crucial for many searches for new physics signals in the next generation of collider experiments. Although these are generally well determined in the small and medium x range, it has been shown that their uncertainty grows rapidly for x >0.1. We examine the status of the gluon and quark distributions in light of new questions that have been raised in the past two years about “large- x ” parton distributions, as well as recent measurements which have improved the parton uncertainties. We perform several specific global fits to answer the outstanding questions, and to investigate the potential of future experiments, particularly at HERA, which may provide critical constraints on parton distributions at large x .
Training in test samples of superconducting cables for accelerator magnets

In the critical current measurement of some high-current NbTi cables, the samples have to be 'trained' by repeated quenching to obtain a usable voltage-current curve for I/sub c/ determination. This training behavior is most pronounced when the applied field is perpendicular to the wide face of the conductor and is strongly dependent on the copper-to-superconductor ratio and the clamping pressure. Data are given for SSC (Superconducting Super Collider) prototype cables as well as for HERA production conductors. Although a quantitative understanding of the experimental data is still lacking, some speculations regarding stability are presented. >
Optimal control of lift/drag ratios on a rotating cylinder

We present the numerical solution to a problem of maximizing the lift to drag ratio by rotating a circular cylinder in a two-dimensional viscous incompressible flow. This problem is viewed as a test case for the newly developing theoretical and computational methods for control of fluid dynamic systems. We show that the time averaged lift to drag ratio for a fixed finite-time interval achieves its maximum value at an optimal rotation rate that depends on the time interval.
Copolymerization of polar monomers with olefins using transition-metal complexes.

Transition-metal catalysts long ago made it from the laboratory bench to the polymerization reactor. Indeed, they are being used around the world to make more than 70 million tons of polyethylene and polypropylene a year. Transition-metal catalysts give polyolefin producers unprecedented flexibility in process and polymer design. However, there are still new worlds for catalysts to conquer. One of the most challenging targets is the controlled copolymerization of simple olefins with polar functional monomers. Success in this area would mark a quantum advance in polyolefin field.
Learning in games

Abstract This essay discusses some recent work on `learning in games'. We explore non-equilibrium theories in which equilibrium emerges as the long-run outcome of a dynamic process of adjustment or learning. We focus on individual level models, and more specifically on variants of `fictitious play' in two-player games. We discuss both the theoretical properties of the models and their relationship to regularities observed in game theory experiments.
Assignment of the liposidomycin diazepanone stereochemistry.

The liposidomycins comprise a family of complex nucleoside antibiotics that inhibit bacterial peptidoglycan synthesis. Their structures (1, 2) feature nucleoside, ribofuranoside, diazepanone, and lipid regions. Several stereogenic centers remain unassigned, including three within the diazepanone region: C-6‘, C-2‘ ‘‘, and C-3‘ ‘‘. An intramolecular reductive amination reaction has been used to prepare model diazepanones. Analysis of 40 and two of its diastereomers by NMR spectroscopy, X-ray crystallography, and molecular modeling indicates a close relative configurational and conformational match between 40 and the liposidomycin diazepanone degradation product 43 and allows the assignment of stereochemistry of the natural products as either [C-6‘(R), C-2‘ ‘‘(R), C-3‘ ‘‘(R)] or [C-6‘(S), C-2‘ ‘‘(S), C-3‘ ‘‘(S)].
A New Resource for College Distance Education Astronomy Laboratory Exercises.

This article introduces a set of distance education astronomy laboratory exercises for use by college students and instructors and discusses first usage results. This General Astronomy Education Source exercise set contains eight two-week projects designed to guide students through both core content and mathematical applications of general astronomy material. Projects are divided between hands-on activities and computer-aided analyses of modern astronomical data. The suite of online resources includes student and instructor guides, laboratory report templates, learning objectives, video tutorials, plotting tools, and web-based applications that allow students to analyze both images and spectra of astronomical objects. A pilot usage study indicates that distance learners using these materials perform as well as or better than a comparison cohort of on-campus students. The authors are actively seeking collaborators to use these resources in astronomy courses and other educational venues.
Parallel fault strands at 9‐km depth resolved on the Imperial Fault, Southern California

[1] Precision relocation of hundreds of small earthquakes occurring along the Imperial Fault in Southern California during the last two decades reveals parallel steaks of seismicity at 9-km depth. These strands are spaced about 0.5 km apart within a 2 km wide zone of earthquakes near the brittle-ductile transition between the shallow locked part of the fault and a creeping zone at depth. These results suggest that the lower crustal shear zone below the Imperial Fault, site of major earthquakes in 1940 and 1979, must be at least two kilometers wide.
Exploring β-Sheet Structure and Interactions with Chemical Model Systems

What I cannot create, I do not understand.—Richard P. Feynman β-Sheets consist of extended polypeptide strands (β-strands) connected by a network of hydrogen bonds and occur widely in proteins. Although the importance of β-sheets in the folded structures of proteins has long been recognized, there is a growing recognition of the importance of intermolecular interactions among β-sheets. Intermolecular interactions between the hydrogen-bonding edges of β-sheets constitute a fundamental form of biomolecular recognition (like DNA base pairing) and are involved protein quaternary structure, protein−protein interactions, and peptide and protein aggregation. The importance of β-sheet interactions in biological processes makes them potential targets for intervention in diseases such as AIDS, cancer, and Alzheimer’s disease. This Account describes my research group’s use of chemical model systems to study the structure and interactions of β-sheets. Chemical model systems provide an excellent vehicle with which to ...
Compatibility, interoperability, and market power in upgrade markets

We examine the market power of a seller who repeatedly offers upgraded versions of a product. In the case of pure monopoly, the seller also controls compatibility across versions. In the case of an entrant who offers an upgrade, the incumbent seller also controls subsequent interoperability across versions. We argue that control of compatibility and interoperability does not allow an incumbent seller to charge a price premium relative to when such control is absent and, consequently, neither is a necessary source of market power.
The rearrangement of 2-amino-5-benzoyloxazoles with dimethylamine

The rearrangement of 2-amino-5-phenacyloxazoles with dimethylamine is described. One such rearrangement provided an unexpected tricyclic product.
Oxygen- and Sulfur-Capped Organotin Clusters

Abstract The synthesis and structural features of the oxygen-capped cluster, [(n-BuSn(OH)O2P (OBut)2)3O] [O2P(OBut)2] (l), are compared to that of the analogous formulations containing framework sulfur atoms in place of oxygens, [(n-BuSn(S) (OH)OP(OBut)2)3S] [O2P(OBut)2]·2H2S·H2O (2) and [(n-BuSn)3(S)(O)(O2CPh)5] (3). Solution NMR, 119Sn and 31P, indicate that the solid state structures determined by X-ray analysis are retained in solution.
Strategic considerations in SETI, and a microwave approach

Abstract The only practical way we know now to actively test the hypothesis that life exists outside the Solar System, depends on an intelligent fraction of that life providing an electromagnetic signature we can recognize over interstellar distances. The nature of the local universe, a relatively mature microwave technology, recent digital solid state developments, and a minimal number of ad hoc assumptions, suggest a promising set of initial strategies of exploration for a range of possible electromagnetic artifacts. As a consequence, the Ames Research Center (ARC) and the Jet Propulsion Laboratory (JPL) are pursuing a moderately broad program using existing radiotelescopes and automated, state-of-the-art electronics, with the objective simply to detect and identify a relatively strong, relatively narrowband, essentially steady, intelligent, non-human, microwave signal. There are two main parts to this approach. In a companion paper, R. E. Edelson (JPL) discusses a survey over 80% of the sky in the 1–25 GHz band, with a frequency resolution of ∼ 300 Hz and to a sensitivity in the range of 10−19 to 10−21 W/m2. The second half of the approach (ARC) discussed here, is a study primarily of neighboring F,G,K, “target” stars in the 1.4–1.7 GHz band, with a frequency resolution of ∼ 1 Hz and to a sensitivity of 10−25 to 10−27 W/m2. Whether or not a detection is achieved, the combined approaches should reduce our present uncertainties by many orders of magnitude, as well as provide valuable astrophysical information.
On Tangential varieties of rational homogeneous varieties

AbstractThe sphericality of tangential varieties of rational homogeneous varieties is determined. The homogeneous coordinate rings and rings of covariants of the tangential varieties of homogenously embedded compact Hermitian symmetric spaces (CHSS) are determined. Bounds on the degrees of generators of the ideals of tangential varieties of CHSS are given, and more explicit information is obtained about the ideals in certain cases.
The WY representation for products of householder matrices

A new way to represent products of Householder matrices is given that makes a typical Householder matrix algorithm rich in matrix-matrix multiplication. This is very desirable in that matrix-matrix...
Examining Fuel Economy and Carbon Standards for Light Vehicles

Under the European Union’s Voluntary Agreement with car manufacturers, average light vehicle CO2 emissions in 2004 were 12.4% below 1995 levels but appeared unlikely to achieve the 25% reduction needed to reach the 140 g/km target for “per vehicle” CO2 emissions for 2008. The EU is now considering a regulatory approach to further reduce average vehicle emissions, in the form of CO2 emission or fuel economy standards. Such standards have been used by a number of countries, including the United States (although U.S. standards have been little-altered since their 1975 promulgation), Japan, China, and several others, and those that have been in existence for some time – e.g., those in the United States and Japan –have been successful in achieving their targeted levels of new vehicle fuel economy. The purpose of this paper is to examine various aspects of fuel economy and carbon standards for light vehicles, including their rationale, methods of establishing stringency, regulatory structure, and timing, with the hope of assisting the decision process for new standards. Because the Corporate Average Fuel Economy (CAFE) standards adopted by the U.S. in 1975 are the longest-standing and most studied of the various standards now in existence, much of the focus of this paper will be on the U.S. standards.
Constructing numerical semigroups of a given genus

Let ng denote the number of numerical semigroups of genus g. Bras-Amoros conjectured that ng possesses certain Fibonacci-like properties. Almost all previous attempts at proving this conjecture were based on analyzing the semigroup tree. We offer a new, simpler approach to counting numerical semigroups of a given genus. Our method gives direct constructions of families of numerical semigroups, without referring to the generators or the semigroup tree. In particular, we give an improved asymptotic lower bound for ng.
Progressing and Oscillatory Waves for Hybrid Synthesis of Source-Excited Propagation and Diffraction

Time-harmonic and transient propagation and diffraction phenomena can be described alternatively by progressing and oscillatory waves that express the wave motion in terms of direct and multiple wavefronts or rays, and in terms of resonances or modes, respectively. Each description is convenient and physically appealing when it requires few contributing elements. It is inconvenient and physically less transparent when it requires many elements, and it would then be desirable to combine many inconvenient elements into fewer convenient ones. For a variety of propagation environments, including layered or other guiding regions, this can be done by expressing a group of rays collectively in terms of modes, or a group of modes collectively in terms of rays. When this ray-mode equivalence is invoked selectively, there emerges a hybrid representation that combines ray fields and modal fields in uniquely defined proportions. The theory is based on Poisson summation and on alternative treatments of wave spectra. It has been applied to electromagnetics, underwater acoustics, and SH elastic motion, and is now being extended to general propagation in elastic media.
Duality for Koszul homology over Gorenstein rings

We study Koszul homology over local Gorenstein rings. It is well known that if an ideal is strongly Cohen–Macaulay the Koszul homology algebra satisfies Poincare duality. We prove a version of this duality which holds for all ideals and allows us to give two criteria for an ideal to be strongly Cohen–Macaulay. The first can be compared to a result of Hartshorne and Ogus; the second is a generalization of a result of Herzog, Simis, and Vasconcelos using sliding depth.
Inner Core Rotation from Geomagnetic Westward Drift and a Stationary Spherical Vortex in Earth's Core

The idea that geomagnetic westward drift indicates convective leveling of the planetary momentum gradient within Earth's core is pursued in search of a differentially rotating mean state, upon which various oscillations and secular effects might be superimposed. The desired state conforms to roughly spherical boundary conditions, minimizes dissipative interference with convective cooling in the bulk of the core, yet may aid core cooling by depositing heat in the uppermost core and lower mantle. The variational calculus of stationary dissipation applied to a spherical vortex within the core yields an interesting differential rotation profile, akin to spherical Couette flow bounded by thin Hartmann layers. Four boundary conditions are required. To concentrate shear induced dissipation near the core-mantle boundary, these are taken to be: (i) no-slip at the core-mantle interface; (ii) geomagnetically estimated bulk westward flow at the base of the core-mantle boundary layer; (iii) no-slip at the inner-outer core interface; and, to describe magnetic locking of the inner core to the deep outer core; (iv) hydrodynamically stress-free at the inner-outer core boundary. By boldly assuming the axial core angular momentum anomaly to be zero, the super-rotation of the inner core relative to the mantle is calculated to be at most 1.5 deg./yr.
Simulation of hypervelocity impact effects on reinforced carbon-carbon

Spacecraft operating in low earth orbit face a significant orbital debris impact hazard. Of particular concern, in the case of the Space Shuttle, are impacts on critical components of the thermal protection system. Recent research has formulated a new material model of reinforced carbon-carbon, for use in the analysis of hypervelocity impact effects on the Space Shuttle wing leading edge. The material model has been validated in simulations of published impact experiments and applied to model orbital debris impacts at velocities beyond the range of current experimental methods. The results suggest that momentum scaling may be used to extrapolate the available experimental data base, in order to predict the size of wing leading edge perforations at impact velocities as high as 13 km/s.
The separation of Willebrand factor from factor VIII-related antigen.

Summary. The three activities associated with factor VIII—coagulant (VIII:C), antigenic (VIIIR:Ag), and platelet agglutinating or Willebrand factor (VIIIR:WF)— have been separated by sequential antibody affinity chromatography, utilizing a rabbit antibody to factor VIII and a spontaneous human antibody to VIII:C. Normal plasma differentially lost its factor VIII-related antigen following passage over the rabbit antibody column. Subsequent passage of the VIIIR:Ag-depleted plasma over the human antibody column resulted in the loss of VIII:C activity, with retention of the Willebrand factor activity, antigen being partially recovered from the heterologous antibody column. These experiments demonstrate that it is possible to separate two of the factor VIII activities, VIIIR:Ag and VIIIR:WF, which are usually regarded as properties of a single molecule.
Line Forces in Keplerian Circumstellar Disks and Precession of Nearly Circular Orbits

We examine the effects of optically thick line forces on orbiting circumstellar disks, such as occur around Be stars. For radially streaming radiation (e.g., as from a point source), line forces are effective only if there is a strong radial velocity gradient, as occurs, for example, in a line-driven stellar wind. However, we emphasize here that, within an orbiting disk, the radial shear of the azimuthal velocity leads to strong line-of-sight velocity gradients along nonradial directions. As such, we show that, in the proximity of a stellar surface extending over a substantial cone angle, the nonradial components of stellar radiation can impart a significant line force to such a disk, even in the case of purely circular orbits with no radial velocity. Given the highly supersonic nature of orbital velocity variations, we use the Sobolev approximation for the line transfer, extending to the disk case the standard CAK formalism developed for line-driven winds. We delineate the parameter regimes for which radiative forces might alter disk properties; but even when radiative forces are small, we analytically quantify higher-order effects in the linear limit, including the precession of weakly elliptical orbits. We find that optically thick line forces, both radial and azimuthal, can have observable implications for the dynamics of disks around Be stars, including the generation of either prograde or retrograde precession in slightly eccentric orbits. However, our analysis here suggests a net retrograde effect, in apparent contradiction with observed long-term variations of violet/red line profile asymmetries from Be stars, which are generally thought to result from prograde propagation of a one-arm, disk-oscillation mode. We also conclude that radiative forces may alter the dynamical properties at the surface of the disk where disk winds originate, and in the outer regions far from the star, and may even make low-density disks vulnerable to being blown off completely.
The effective conductivity of an infinitely interchangeable mixture

We are concerned with the estimation of the effective electrical conductivity of random heterogenous materials. The purpose of this paper is to discuss a property of “statistical symmetry” verified by the symmetric cell materials of Miller. This property will be referred to as infinite interchangeability. The usual way to approach cell materials is through n-point correlation functions. The property of infinite interchangebility permits us to approach cell materials from a completely different point of view. Our main result is a simple algorithm, based on this symmetry property, for computing any coefficient of the perturbation expansion in terms of information from the dilute limit. Specifically, knowledge of the coefficients of the expansion in powers of the volume fraction up to order r allows for computation of the perturbation expansion coefficients up to order (2r + 1). This result, which was previously known for r = 2 in the isotropic case and for r = 1 in the anisotropic case, can also be obtained from the standard correlation function approach, as pointed out by Milton.
High-resolution force microscopy of in-plane magnetization

We have shown for the first time, in previous studies, that the force microscope fitted with a magnetic tip could be used to image magnetic domains in TbFe thin films. In this report we show that the information provided by the magnetic force microscope can also include a measurement of the component of magnetization in the sample which is parallel to the surface. Measurements were taken with a magnetized tip tilted at 45° with respect to the surface normal. In a first experiment, we imaged 1μm diameter domains thermomagnetically written in a TbFe thin film. In a second measurement, we imaged a series of alternating domains in a thin film Co-alloy disc which was decorated with small magnetized particles, allowing unambiguous identification of the domain boundaries. In both cases we interpret the asymmetric portion of the images to the in-plane component of the sample magnetization.
Estimating the market effect of a food scare: The case of genetically modified StarLink corn

Abstract In 2000, a genetically modified corn variety called StarLink that was not approved for human consumption was discovered in the food-corn supply. To estimate the price impact of this event on the U.S. corn market, we develop the relative price of a substitute method. This method applies not only to the StarLink event but also to rare events in other markets. We find that the contamination led to a 6.8% discount in corn prices and that the suppression of prices lasted for at least a year.
Vortex dynamics of blade-blade interaction

A time domain method has been developed for treatments of vortex dynamics in all classes of blade-blade interaction problems. A new vortex impingement condition is introduced to the discrete vortex tracking scheme and was found most effective in handling the vortex-airfoil interaction and the blade-blade interaction (BBI) problems. Present results are verified with all classical solutions and are found in good agreement with almost all existing solutions. The present BBI study concludes that any front blade movement will induce a strong interaction between the wake and the rear blade; hence, it alters drastically the lift response and the wake structure. Any rear blade movement only induces a weak interaction, hence rendering the blade system ineffective
Geometric singularities and enhanced gauge symmetries

Abstract Using “Tate's algorithm,” we identify loci in the moduli of F-theory compactifications corresponding to enhanced gauge symmetry. We apply this to test the proposed F-theory/heterotic dualities in six dimensions. We recover the perturbative gauge symmetry enhancements of the heterotic side and the physics of small SO (32) instantons, and discover new mixed perturbative/nonperturbative gauge symmetry enhancements. Upon further toroidal compactification to four dimensions, we derive the chain of Calabi-Yau threefolds dual to various Coulomb branches of heterotic strings.
Reduction of prostate intrafraction motion using gas-release rectal balloons

Purpose: To analyze prostate intrafraction motion using both non-gas-release (NGR) and gas-release (GR) rectal balloons and to evaluate the ability of GR rectal balloons to reduce prostate intrafraction motion. Methods: Twenty-nine patients with NGR rectal balloons and 29 patients with GR balloons were randomly selected from prostate patients treated with proton therapy at University of Florida Proton Therapy Institute (Jacksonville, FL). Their pretreatment and post-treatment orthogonal radiographs were analyzed, and both pretreatment setup residual error and intrafraction-motion data were obtained. Population histograms of intrafraction motion were plotted for both types of balloons. Population planning target-volume (PTV) margins were calculated with the van Herk formula of 2.5{Sigma}+ 0.7{sigma} to account for setup residual errors and intrafraction motion errors. Results: Pretreatment and post-treatment radiographs indicated that the use of gas-release rectal balloons reduced prostate intrafraction motion along superior-inferior (SI) and anterior-posterior (AP) directions. Similar patient setup residual errors were exhibited for both types of balloons. Gas-release rectal balloons resulted in PTV margin reductions from 3.9 to 2.8 mm in the SI direction, 3.1 to 1.8 mm in the AP direction, and an increase from 1.9 to 2.1 mm in the left-right direction. Conclusions: Prostate intrafraction motion is an important uncertainty source inmore » radiotherapy after image-guided patient setup with online corrections. Compared to non-gas-release rectal balloons, gas-release balloons can reduce prostate intrafraction motion in the SI and AP directions caused by gas buildup.« less
Stereoselective formation of fused tricyclic amines from acyclic aldehydes by a cascade process involving condensation, cyclization, and dipolar cycloaddition.

The preparation of tricyclic amines from acyclic precursors is described using a cascade of tandem reactions involving condensation of an aldehyde with a primary amine, cyclization (with displacement of a halide), and then in situ deprotonation or decarboxylation to give an azomethine ylide or nitrone followed by intramolecular dipolar cycloaddition. The methodology is straightforward, and the aldehyde precursors are prepared easily and quickly in high yield using nitrile alkylations followed by DIBAL-H reduction. The relative ease of reaction of various substrates with different tether lengths between the aldehyde and the halide or dipolarophile has been studied. Several primary amines including simple amino acids such as glycine, alanine, and phenylalanine and derivatives such as glycine ethyl ester and also hydroxylamine have been investigated. High yields are obtained in the formation of different tricyclic ring sizes; the dipolar cycloaddition necessarily creates a five-membered ring, and we have inv...
Double Coronal Hard and Soft X-Ray Source Observed by RHESSI: Evidence for Magnetic Reconnection and Particle Acceleration in Solar Flares

We present data analysis and interpretation of an M1.4 class flare observed with the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) on 2002 April 30. This event, with its footpoints occulted by the solar limb, exhibits a rarely observed, but theoretically expected, double-source structure in the corona. The two coronal sources, observed over the 6-30 keV range, appear at different altitudes and show energy-dependent structures with the higher energy emission being closer together. Spectral analysis implies that the emission at higher energies in the inner region between the two sources is mainly nonthermal, while the emission at lower energies in the outer region is primarily thermal. The two sources are both visible for about 12 minutes and have similar light curves and power-law spectra above about 20 keV. These observations suggest that the magnetic reconnection site lies between the two sources. Bidirectional outflows of the released energy in the form of turbulence and/or particles from the reconnection site could be the source of the observed radiation. The spatially resolved thermal emission below about 15 keV, on the other hand, indicates that the lower source has a larger emission measure but a lower temperature than the upper source. This is likely the result of the differences in the magnetic field and plasma density of the two sources.
Prediction of potency of protease inhibitors using free energy simulations with polarizable quantum mechanics-based ligand charges and a hybrid water model.

Reliable and robust prediction of the binding affinity for drug molecules continues to be a daunting challenge. We simulated the binding interactions and free energy of binding of nine protease inhibitors (PIs) with wild-type and various mutant proteases by performing GBSA simulations in which each PI’s partial charge was determined by quantum mechanics (QM) and the partial charge accounts for the polarization induced by the protease environment. We employed a hybrid solvation model that retains selected explicit water molecules in the protein with surface-generalized Born (SGB) implicit solvent. We examined the correlation of the free energy with the antiviral potency of PIs with regard to amino acid substitutions in protease. The GBSA free energy thus simulated showed strong correlations (r > 0.75) with antiviral IC50 values of PIs when amino acid substitutions were present in the protease active site. We also simulated the binding free energy of PIs with P2-bis-tetrahydrofuranylurethane (bis-THF) or re...
Heat Transfer Enhancement by EHD-Induced Oscillatory Flows

Prior numerical solutions of electrohydrodynamic (EHD) gas flows in a horizontal channel with a positive-corona discharged wire have revealed the existence of steady-periodic flows. It is speculated that heat transfer by forced convection may be greatly enhanced by taking advantage of this oscillatory flow phenomenon induced by electric field. To verify this speculation, computations have been performed for flows with Reynolds numbers varying from 0 to 4800 and the dimensionless EHD number (which signifies the effect of electric field) ranging from 0.05 to ∞. The results show that heat transfer enhancement increases with the applied voltage. For a given electric field, oscillation in the flow and temperature fields occurs at small Reynolds numbers. Due to the presence of oscillatory secondary flows, there is a significant enhancement in heat transfer.
Batalin-Vilkovisky Lie Algebra Structure on the Loop Homology of Complex Stiefel Manifolds

We determine the Batalin-Vilkovisky Lie algebra structure for the integral loop homology of special unitary groups and complex Stiefel manifolds. It is shown to coincide with the Poisson algebra structure associated to a certain odd symplectic form on a super vector space for which loop homology is the super algebra of functions. Over rationals, the loop homology of the above spaces splits into a tensor product of simple BV algebras, and it is shown to contain a super Lie algebra.
Transportability of Causal and Statistical Relations: A Formal Approach

We address the problem of transferring information learned from experiments to a different environment, in which only passive observations can be collected. We introduce a formal representation called ``selection diagrams'' for expressing knowledge about differences and commonalities between environments and, using this representation, we derive procedures for deciding whether effects in the target environment can be inferred from experiments conducted elsewhere. When the answer is affirmative, the procedures identify the set of experiments and observations that need be conducted to license the transport. We further discuss how transportability analysis can guide the transfer of knowledge in non-experimental learning to minimize re-measurement cost and improve prediction power.
Analytical and experimental investigation of bird impact on fan and compressor blading

Etude analytique et experimentale du choc d'un oiseau sur l'aubage d'une soufflante et d'un compresseur
Friends and Family: How In-Group-Focused Promotions Can Increase Purchase

Firms use large majorities of their budgets on sales promotions such as coupons and sales events. Many of these sales promotions are framed as “friends and family” or “preferred customer.” Which of these frames is more effective, when, and why? We answer these questions building on existing research on deal exclusivity. We show that the success of promotions framed as in-group vs. self-focused depends on whether they are targeted toward interdependent or independent customers. We find that interdependent customers are more receptive to in-group-focused promotions because they perceive such promotions as being higher-value deals. We also show that consistency with brand personality matters: the benefit of in-group-focused promotions for interdependent consumers is higher for brands with a group-oriented personality. Overall, these results show how sales promotions can be more effective without having to increase the magnitude of the promotion.
Establishment Size Dynamics in the Aggregate Economy

Why do growth and net exit rates of establishments decline with size? What determines the size distribution of establishments? This paper presents a theory of establishment dynamics that simultaneously rationalizes the basic facts on economy-wide establishment growth, net exit, and size distributions. The theory emphasizes the accumulation of industry-speci…c human capital in response to industry-speci…c productivity shocks. It predicts that establishment growth and net exit rates should decline faster with size and that the establishment size distribution should have thinner tails in sectors that use human capital less intensively or physical capital more intensively. In line with the theory, the data show substantial sectoral heterogeneity in U.S. establishment size dynamics and distributions, which is well explained by variation in physical capital intensity.
Prevention of glucocorticoid induced-apoptosis of osteoblasts and osteocytes by protecting against endoplasmic reticulum (ER) stress in vitro and in vivo in female mice☆

article i nfo Endoplasmic reticulum (ER) stress is associated with increased reactive oxygen species (ROS),results from accu- mulation of misfolded/unfolded proteins, and can trigger apoptosis. ER stress is alleviated by phosphorylation of eukaryotic translation initiation factor 2α (eIF2α), which inhibits protein translation allowing the ER to recover, thus promoting cell viability. We investigated whether osteoblastic cell apoptosis induced by glucocorticoids (GCs) is due to induction of ROS/ER stress and whether inhibition of eIF2α dephosphorylation promotes survival opposing the deleterious effects of GC in vitro and in vivo. Apoptosis of osteocytic MLO-Y4 and osteoblastic OB-6 cellsinducedby dexamethasone wasabolishedbyROSinhibitors.LikeGC,theERstressinducingagentsbrefeldin A and tunicamycin induced osteoblastic cell apoptosis. Salubrinal or guanabenz, specific inhibitors of eIF2α dephosphorylation,blockedapoptosisinducedbyeitherGC or ER stress inducers.Moreover,GC markedlydecreased mineralization in OB-6 cells or primary osteoblasts; and salubrinal or guanabenz increased mineralization and prevented the inhibitory effect of GC. Furthermore, salubrinal (1 mg/kg/day) abolished osteoblast and osteocyte ap- optosis in cancellous and cortical bone and partially prevented the loss of BMD at all sites and the decreased verte- bral cancellous bone formation induced by treatment with prednisolone for 28 days (1.4 mg/kg/day). We conclude that part of the pro-apoptotic actions of GC on osteoblastic cells is mediated through ER stress, and that inhibition of eIF2α dephosphorylation protects from GC-induced apoptosis of osteoblasts and osteocytes in vitro and in vivo and from the deleterious effects of GC on the skeleton.
Mechanisms of Catalyst Poisoning by Sulfur Species

Summary The term ‘catalyst deactivation’ or ‘catalyst poisoning' generally refers to a decline in the rate of catalytic conversion and/or a variation in product selectivity as a result of physically or chemically induced changes of the catalyst. In terms of physical changes the deactivation process may involve crystallite growth, reconstruction accompanied by the formation of new surface structures and coordination sites, and surface enrichment or depletion with respect to bulk components. In terms of chemical changes the adsorption of gaseous impurities from the feed is the most common source of catalyst poisoning. The adspecies of major concern contain sulfur, phosphorous, halogens, and carbon. Thermodynamic measurements of surface-vapor equilibria demonstrate the magnitude of the binding energies involved. Segregation studies of different components from the bulk phase to the surface have provided considerable insight into the mechanism and kinetics of adsorbate-induced surface modifications. Recently the surface transport of adspecies involving reaction intermediates and catalyst poisons has received attention. Surface diffusion rates are greater by several orders of magnitude than those for bulk diffusion. For Ni(111)-S the variation of the surface diffusion coefficient with sulfur coverage has been correlated with changes in binding energy.
Static Formations Using Momentum Exchange Between Satellites

Feasible operations of satellite formations are dependent upon an efficient way to affect the relative motion. One possible means of formation stationkeeping is for satellites to exchange momentum in the form of radiation or mass. This approach could potentially provide a mutually repulsive force between satellites without the expenditure of propellant. This paper characterizes equilibria positions in the rotating orbital frame for an arbitrary number of satellites subjected to equal and opposite repulsive force between specifiable satellite pairs. Equilibrium configurations are found that allow arbitrary dispersion in the plane perpendicular to nadir. Stability analysis of these equilibria show stable out-of-plane motion and unstable in-plane motion. A strategy is developed to stabilize the system and to reconfigure the formation geometry. Finally, a simulation including Earth oblateness demonstrates the dynamic feasibility of this method of orbit control.
ASGARD: A LARGE SURVEY FOR SLOW GALACTIC RADIO TRANSIENTS. I. OVERVIEW AND FIRST RESULTS

Searches for slow radio transients and variables have generally focused on extragalactic populations, and the basic parameters of Galactic populations remain poorly characterized. We present a large 3 GHz survey performed with the Allen Telescope Array (ATA) that aims to improve this situation: ASGARD, the ATA Survey of Galactic Radio Dynamism. ASGARD observations spanned two years with weekly visits to 23 deg{sup 2} in two fields in the Galactic plane, totaling 900 hr of integration time on science fields and making it significantly larger than previous efforts. The typical blind unresolved source detection limit was 10 mJy. We describe the observations and data analysis techniques in detail, demonstrating our ability to create accurate wide-field images while effectively modeling and subtracting large-scale radio emission, allowing standard transient-and-variability analysis techniques to be used. We present early results from the analysis of two pointings: one centered on the microquasar Cygnus X-3 and one overlapping the Kepler field of view (l = 76 Degree-Sign , b = +13. Degree-Sign 5). Our results include images, catalog statistics, completeness functions, variability measurements, and a transient search. Out of 134 sources detected in these pointings, the only compellingly variable one is Cygnus X-3, and no transients aremore » detected. We estimate number counts for potential Galactic radio transients and compare our current limits to previous work and our projection for the fully analyzed ASGARD data set.« less
A new preparation of ethyl 3-oxo-4-pentenoate: A useful annelating reagent

La synthese se fait a partir d'une addition d'acroleine a des acetates suivie d'une oxydation de Jones'
Negative Polarity Licensing at the Syntax-Semantics Interface

Recent work on the syntax-semantics interface (see e.g. (Dalrymple et al., 1994)) uses a fragment of linear logic as a 'glue language' for assembling meanings compositionally. This paper presents a glue language account of how negative polarity items (e.g. ever, any) get licensed within the scope of negative or downward-entailing contexts (Ladusaw, 1979), e.g. Nobody ever left. This treatment of licensing operates precisely at the syntax-semantics interface, since it is carried out entirely within the interface glue language (linear logic). In addition to the account of negative polarity licensing, we show in detail how linear-logic proof nets (Girard, 1987; Gallier, 1992) can be used for efficient meaning deduction within this 'glue language' framework.
Euler characteristics of general linear sections and polynomial Chern classes

We obtain a precise relation between the Chern–Schwartz–MacPherson class of a subvariety of projective space and the Euler characteristics of its general linear sections. In the case of a hypersurface, this leads to simple proofs of formulas of Dimca–Papadima and Huh for the degrees of the polar map of a homogeneous polynomial, extending these formula to any algebraically closed field of characteristic \(0\), and proving a conjecture of Dolgachev on ‘homaloidal’ polynomials in the same context. We generalize these formulas to subschemes of higher codimension in projective space. We also describe a simple approach to a theory of ‘polynomial Chern classes’ for varieties endowed with a morphism to projective space, recovering properties analogous to the Deligne–Grothendieck axioms from basic properties of the Euler characteristic. We prove that the polynomial Chern class defines homomorphisms from suitable relative Grothendieck rings of varieties to \(\mathbb{Z }[t]\).