cssi/SciSciGPT-SciSciNet huggingface dataset:
Tunable Vibrational Band Gaps in One-Dimensional Diatomic Granular Crystals with Three-Particle Unit Cells

We investigate the tunable vibration filtering properties of statically compressed one-dimensional diatomic granular crystals composed of arrays of stainless steel spheres and cylinders interacting via Hertzian contact. The arrays consist of periodically repeated three-particle unit cells (sphere-cylinder-sphere) in which the length of the cylinder is varied systematically. We investigate the response of these granular crystals, given small amplitude dynamic displacements relative to those due to the static compression, and characterize their linear frequency spectrum. We find good agreement between theoretical dispersion relation analysis (for infinite systems), state-space analysis (for finite systems), and experiments. We report the observation of three distinct pass bands separated by two finite band gaps, and show their tunability for variations in cylinder length and static compression.
Nearly flat band with Chern number C=2 on the dice lattice

We point out the possibility of a nearly flat band with Chern number $C=2$ on the dice lattice in a simple nearest-neighbor tight-binding model. This lattice can be naturally formed by three adjacent $(111)$ layers of cubic lattice, which may be realized in certain thin films or artificial heterostructures, such as the SrTiO${}_{3}$/SrIrO${}_{3}$/SrTiO${}_{3}$ trilayer heterostructure grown along the $(111)$ direction. The flatness of two bands is protected by the bipartite nature of the lattice. Including the Rashba spin-orbit coupling on nearest-neighbor bonds causes the flat bands to separate from the others but maintain their flatness. Repulsive interaction will drive spontaneous ferromagnetism on the Kramer pair of the flat bands and split them into two nearly flat bands with Chern number $C=\ifmmode\pm\else\textpm\fi{}2$. We thus propose that this may be a route to the quantum anomalous Hall effect and further conjecture that the partial filling of the $C=2$ band may realize exotic fractional quantum Hall effects.
Optimal Multistage Sampling in a Boundary-Crossing Problem

Brownian motion with known positive drift is sampled in stages until it crosses a positive boundary a. A family of multistage samplers that control the expected overshoot over the boundary by varying the stage size at each stage is shown to be optimal for large a, minimizing a linear combination of overshoot and number of stages. Applications to hypothesis testing are discussed.
Factored axis-aligned filtering for rendering multiple distribution effects

Monte Carlo (MC) ray-tracing for photo-realistic rendering often requires hours to render a single image due to the large sampling rates needed for convergence. Previous methods have attempted to filter sparsely sampled MC renders but these methods have high reconstruction overheads. Recent work has shown fast performance for individual effects, like soft shadows and indirect illumination, using axis-aligned filtering. While some components of light transport such as indirect or area illumination are smooth, they are often multiplied by high-frequency components such as texture, which prevents their sparse sampling and reconstruction. We propose an approach to adaptively sample and filter for simultaneously rendering primary (defocus blur) and secondary (soft shadows and indirect illumination) distribution effects, based on a multi-dimensional frequency analysis of the direct and indirect illumination light fields. We describe a novel approach of factoring texture and irradiance in the presence of defocus blur, which allows for pre-filtering noisy irradiance when the texture is not noisy. Our approach naturally allows for different sampling rates for primary and secondary effects, further reducing the overall ray count. While the theory considers only Lambertian surfaces, we obtain promising results for moderately glossy surfaces. We demonstrate 30x sampling rate reduction compared to equal quality noise-free MC. Combined with a GPU implementation and low filtering over-head, we can render scenes with complex geometry and diffuse and glossy BRDFs in a few seconds.
Mitigating the Myopia of Dominant Logics: On Differential Performance and Strategic Supply Chain Research

The primary question of management scholarship is, “What leads some firms to be successful even as others fail?” Over the years, a variety of dominant logics have emerged to inform this question. Synthesized, these logics make it clear that companies win when they create customer value better than the competition and efficiently enough to be profitable. That is, firms that design distinctive and dynamic value-added systems win competitive battles. This observation is salient to the Journal of Business Logistics community as systems design and value creation are focal decision areas of supply chain management. With this in mind, we briefly discuss two of many areas for which strategic supply chain research can inform differential performance.
A Basic class of twisted open WZW strings

Recently, Giusto and Halpern reported the open-string description of a certain basic class of untwisted open WZW strings, including their associated noncommutative geometry and open-string KZ equations. In this paper, we combine this development with results from the theory of current-algebraic orbifolds to find the open-string description of a corresponding basic class of twisted open WZW strings, which begin and end on different WZW branes. The basic class of twisted open WZW strings is in 1-to-1 correspondence with the twisted sectors of all closed-string WZW orbifolds, and moreover, the basic class can be decomposed into a large collection of open-string WZW orbifolds. At the classical level, these open-string orbifolds exhibit new twisted noncommutative geometries, and we also find the relevant twisted open-string KZ equations which describe these orbifolds at the quantum level. In a related development, we also formulate the closed-string description (in terms of twisted boundary states) of the general twisted open WZW string.
Soft X-rays from the sunlit earth's atmosphere

Observations of soft X-ray emission from the sunlit earth atmosphere are presented and compared with the predictions of an earth albedo X-ray theory. The exact theory accounts for the flux of Thomson scattered solar X rays and fluorescently excited K X rays that arise following the absorption of incident X rays as a function of observing geometry. Observations were made at widely separated geometries with the two low-energy detectors of the A-2 experiment on the HEAO-1 satellite. Fitting of the model to the observed spectra results in values for the solar coronal temperature and emission measure that are in good agreement with expected values for the nonflaring sun, indicating that X-ray observations of the sunlit atmosphere may be a useful monitor of solar activity for satellites unable to view the sun directly. The total measured fluorescent line flux is also in agreement with calculations, although the N/O line ratio is not. X-ray fluorescence measurements from the sunlit atmosphere will thus be useful in monitoring atmospheric composition only to the extent that the total line counting rates depend upon the composition.
Analyzing the Error Bounds of Multipole-Based Treecodes

Abstract: The problem of evaluating the potential due to a set of particles is an important and time- consuming one. The development of fast treecodes such as the Barnes-Hut and Fast Multipole Methods for n-body systems has enabled large scale simulations in astrophysics [9, 10, 13] and molecular dynamics [1]. Coupled with efficient parallel processing, these treecodes are capable of yielding several orders of magnitude improvement in performance [6, 14, 15]. In addition, treecodes have applications in the solution of dense linear systems arising from boundary element methods [3, 4, 5, 11, 12]. Using a p-term multipole expansion, the FMM reduces the complexity of a single timestep from O(n2) to O(p2n) and Barnes-Hut method reduces it to O(p2log n) for a uniform distribution. In this paper, we analyze the approximations introduced by these methods. We describe an algorithm that reduces the error significantly by selecting the multipole degree appropriately for different clusters. Furthermore, we show that for practical problem sizes, this increases the computational complexity marginally. We support our theoretical result with experiments in the context of particle simulations as well as boundary element methods. Our POSIX threads-based treecode yields excellent speedups on a 32 processor SGI Origin 2000, even for relatively small problems.
Cyclic cohomology of Hopf algebras of transverse symmetries in codimension 1

Abstract We develop intrinsic tools for computing the periodic Hopf cyclic cohomology of Hopf algebras related to transverse symmetry in codimension 1. Besides the Hopf algebra found by Connes and the first author in their work on the local index formula for transversely hypoelliptic operators on foliations, this family includes its ‘Schwarzian’ quotient, on which the Rankin–Cohen universal deformation formula is based, the extended Connes–Kreimer Hopf algebra related to renormalization of divergences in QFT, as well as a series of cyclic coverings of these Hopf algebras, motivated by the treatment of transverse symmetry for non-orientable foliations. The method for calculating their Hopf cyclic cohomology is based on two computational devices, which work in tandem and complement each other: one is a spectral sequence for bicrossed product Hopf algebras and the other a Cartan-type homotopy formula in Hopf cyclic cohomology.
Paired approximation problems and incompatible inapproximabilities

This paper considers pairs of optimization problems that are defined from a single input and for which it is desired to find a good approximation to either one of the problems. In many instances, it is possible to efficiently find an approximation of this type that is better than known inapproximability lower bounds for either of the two individual optimization problems forming the pair. In particular, we find either a (1 + e)-approximation to (1, 2)-TSP or a 1/e-approximation to maximum independent set, from a given graph, in linear time. We show a similar paired approximation result for finding either a coloring or a long path. However, no such tradeoff exists in some other cases: for set cover and hitting set problems defined from a single set family, and for clique and independent set problems on the same graph, it is not possible to find an approximation when both problems are combined that is better than the best approximation for either problem on its own.
Experimental distinction between the quantum and classical field-theoretic predictions for the photoelectric effect

We have measured various coincidence rates between four photomultiplier tubes viewing cascade photons on opposite sides of dielectric beam splitters. This experimental configuration, we show, is sensitive to differences between the classical and quantum field-theoretic predictions for the photoelectric effect. The results, to a high degree of statistical accuracy, contradict the predictions by any classical or semiclassical theory in which the probability of photoemission is proportional to the classical intensity.
Fractional charge, a sharp quantum observable

The magnitude of quantum fluctuations of the charge of a fractionally charged soliton is calculated. The soliton charge operator is defined as ${\stackrel{^}{Q}}_{s}={\stackrel{^}{Q}}_{f}\ensuremath{-}〈0|{\stackrel{^}{Q}}_{f}|0〉$, where ${\stackrel{^}{Q}}_{f}$ is the integral of the charge-density operator sampled by a function $f$ peaked at the position of the soliton, and falling smoothly to zero on a scale $L$. $|0〉$ is the ground state of the system in the absence of solitons. It is shown that the mean-square fluctuation of ${\stackrel{^}{Q}}_{s}$ taken about its fractional average value ${Q}_{s}$ vanishes as $O(\frac{{\ensuremath{\xi}}_{0}}{L})$ for $Lgg{\ensuremath{\xi}}_{0}$, where ${\ensuremath{\xi}}_{0}$ is the width of the soliton. Thus, as $L\ensuremath{\rightarrow}\ensuremath{\infty}$, the soliton is an eigenfunction of the charge operator with fractional eigenvalue. We also show that the portion of the charge fluctuations that are due to the soliton falls as $\mathrm{exp}(\frac{\ensuremath{-}L}{{\ensuremath{\xi}}_{0}})$ as $L\ensuremath{\rightarrow}\ensuremath{\infty}$. Nonetheless, the charge of the entire system, including all solitons, is integral.
Cross-Calibration of TIMED SEE and SOHO EIT Irradiances

Absolutely calibrated solar images are necessary for a variety of solar physics problems, such as the identification of solar variability sources and the derivation of differential emission measure (DEM) maps. SOHO EIT is absolutely calibrated by using TIMED SEE spectra to provide a method of determining physical values of irradiance for EIT images. EIT images from 1 April 2002 to 15 March 2005 in the 28.4- and 30.4-nm channels are compared to SEE daily spectra from the same time period. The resulting fitted EIT irradiances are well correlated to SEE irradiance measurements and are within the uncertainties of both instruments. The new cross-calibration results are compared to the currently used calibration based on the UARS SUSIM Mg ii index.
Strongly meager and strong measure zero sets

In this paper we present two consistency results concerning the existence of large strong measure zero and strongly meager sets. RID=""ID="" Mathematics Subject Classification (2000): 03E35 RID=""ID="" The first author was supported by Alexander von Humboldt Foundation and NSF grant DMS 95-05375. The second author was partially supported by Basic Research Fund, Israel Academy of Sciences, publication 658
Establishment of a coastal setback line in Florida

Florida recently required coastal construction setback lines along its sand beaches fronting the ocean and Gulf. The Coastal Laboratory, University of Florida, has a research contract to provide the technical information and make recommendations for establishment of the setback lines. The study included historical research related to shoreline stability, field measurements and analytical evaluation. Factors considered were upland topography, vegetation, bathymetry, shoreline stability (erosion trends), storm surges, wave setup and uprush, dune/beach erosion due to storms, existing coastal structures, beach nourishment and upland development. Analysis of the pertinent factors resulted in formulation of criteria that were applied in establishment of the setback lines. Management of beach development is possible utilizing engineering/scientific investigation however the study pointed to areas of much needed research in the Coastal Zone.
Rapid determination of PEGylated liposomal doxorubicin and its major metabolite in human plasma by ultraviolet-visible high-performance liquid chromatography.

A high-performance liquid chromatographic method was developed for the quantification of doxorubicin derived from PEGylated liposomal doxorubicin (Doxil) and its major metabolite in human plasma. This method utilizes Triton X-100 to disperse the liposome, followed by a protein precipitation step with 5-sulfosalicylic acid. Analytes in the resultant supernatant are separated on a Discovery RP amide C(16) column (250 x 3 mm I.D., 5 microm) using an isocratic elution with a mobile phase consisting of 0.05 M sodium acetate (pH 4.0) and acetonitrile (72:28). The retention times for doxorubicin and the internal standard daunorubicin were 4.8 and 10.1 min, respectively. The column eluate was monitored by UV-visible detection at 487 nm. The determination of doxorubicin was found to be linear in the range of 1.0 ng/mL to 25 microg/mL, with intra-day and inter-day coefficients of variation and percent error 69.3%, with a liposomal dispersion efficiency of >95.7%. Our analytical method for free and PEGylated doxorubicin in human plasma is rapid, avoids organic extractions, and maintains sensitivity for the parent compound and its major metabolite, doxorubicinol.
Approximability of flow shop scheduling

Shop scheduling problems are notorious for their intractability, both in theory and practice. In this paper, we construct a polynomial approximation scheme for the flow shop scheduling problem with an arbitrary fixed number of machines. For the three common shop models (open, flow, and job), this result is the only known approximation scheme. Since none of the three models can be approximated arbitrarily closely in the general case (unless P = NP), the result demonstrates the approximability gap between the models in which the number of machines is fixed, and those in which it is part of the input of the instance. The result can be extended to flow shops with job release dates and delivery times and to flow shops with a fixed number of stages, where the number of machines at any stage is fixed. © 1998 The Mathematical Programming Society, Inc. Published by Elsevier Science B.V.
The evolution of a turbulent vortex

We examine numerically the evolution of a perturbed vortex in a periodic box. The fluid is inviscid. We find that the vorticity blows up. The support of theL2 norm of the vorticity converges to a set of Hausdorff dimension ∼2.5. The distribution of the vorticity seems to converge to a lognormal distribution. We do not observe a convergence of the higher statistics towards universal statistics, but do observe a strong temporal intermittency.
Repeated games, finite automata, and complexity

We study the structure of Nash equilibria in 2-player repeated games played with finite automata, when complexity considerations matter. We argue that the traditional number-of-states measure of complexity of an automaton neglects some essential features such as informational requirements at a state. We propose a criterion of complexity to remedy this; our criterion takes into account both the size (number of states) and transitional structure of a machine. We prove that the resulting Nash equilibria of the machine game are now trivial: the machines recommend actions every period that are invariably stage-game Nash equilibria.
Synthesis and structure-DNA binding relationship analysis of DNA triple-helix specific intercalators.

4-[N-(Aminoalkyl)amino]-2-arylquinolines with conformational freedom around positions 2 and 4 of the quinoline stabilize strongly poly(dT·dA·dT) (triplex DNA) and bind weakly to poly(dA·dT) (duplex DNA). Basicity of N1 of the quinoline parallels the interaction strength of these compounds with the triple-helical DNA structure suggesting that N1 of the quinoline is protonated in the complex with the DNA triplex. The experimental results support the interaction model suggested previously (Wilson et al. Biochemistry 1993, 32, 10614).
Laser photolysis and ionization of polyatomic molecules: Film growth and spectroscopic diagnostics

Experiments are described in which semiconductor or metal films are grown from the vapor phase by photodissociating or photoionizing diatomic or polyatomic molecules. The photolysis of GeH 4 at 248 nm Mw = 5 eV) is initiated by a two photon process that liberates the germylene radical GeH 2 . Spatially and temporally-resolved concentration profiles for several excited states of GeH and atomic Ge have been measured near the substrate. Thin indium films have been deposited on nickel substrates by dissociatively ionizing indium monoiodide (InI) to produce In + - I - ion pairs. The dynamics of ion pair production for thallium iodide or InI vapor photoexcited at 193 nm have been studied by combining an excimer laser with microwave absorption techniques.
Electrochemical and Electrochromic Behavior of Reactively Sputtered Nickel Oxide

Nickel oxide thin films were deposited by reactive sputtering in a 20% oxygen/argon atmosphere for use as oxygen evolution catalysts in the photoelectrochemical production of hydrogen. The optical properties of the films were also characterized to evaluate their application as window layers. The polycrystalline films deposited at residual gas pressures of 6 or 10 mTorr exhibited moderate activity for oxygen evolution in 1 N KOH and pronounced coloration and bleaching during alternating anodic/cathodic bias. Properties of these films were not sensitive to growth rate over the range studied, 0.5 to 4 {angstrom}/s. In contrast, films deposited at 2 mTorr exhibited poor activity for oxygen evolution and severely limited electrochromic behavior which the authors attribute to marked changes in the morphology and crystallinity in the low-pressure films. The films grown at 6 mTorr and higher tended to be more oriented, to have a higher degree of crystallinity, and higher oxygen content. Strong linkages between the electrochemical and optical behaviors observed in this work provide new insights into the processes involved in oxygen evolution reaction catalysis and electrochromism in reactively sputtered NiO{sub x} films. The results presented indicate that reactive sites located on or near grain boundaries are responsible for both behaviors.
The SEC's elimination of 20-F reconciliation and information asymmetry

Abstract The U.S. SEC adopted a rule in December 2007 to eliminate the 20-F reconciliation requirement for foreign private issuers preparing financial statements under IFRS as issued by the IASB. In this paper we examine whether eliminating the reconciliation is associated with information asymmetry for such foreign issuers during the 2005–2008 sample period. We find that information asymmetry decreases after such firms discontinue the 20-F reconciliation. Moreover, information asymmetry reduction is more pronounced for firms with higher reconciliation constraint proxied by higher pre-rule disclosure incentive and for firms with higher cost savings proxied by more reductions in audit fees in the post-rule period. We also document that foreign IFRS firms change accounting policies more frequently than foreign non-IFRS firms after the relaxation of the reconciliation constraint. Together, these findings provide empirical evidence supporting the SEC's decision to eliminate the 20-F reconciliation.
A Novel B(C6F5)3-Catalyzed Reduction of Alcohols and Cleavage of Aryl and Alkyl Ethers with Hydrosilanes†

The primary alcohols 1a−e and ethers 4a−d were effectively reduced to the corresponding hydrocarbons 2 by HSiEt3 in the presence of catalytic amounts of B(C6F5)3. To the best of our knowledge, this is the first example of catalytic use of Lewis acid in the reduction of alcohols and ethers with hydrosilanes. The secondary alkyl ethers 4j,k enabled cleavage and/or reduction under similar reaction conditions to produce either the silyl ethers 3m−n or the corresponding alcohol 5a upon subsequent deprotection with TBAF. It was found that the secondary alcohols 1g−i and tertiary alcohol 1j, as well as the tertiary alkyl ether 4l, did not react with HSiEt3/(B(C6F5)3 reducing reagent at all. The following relative reactivity order of substrates was found: primary ≫ secondary > tertiary. A plausible mechanism for this nontraditional Lewis acid catalyzed reaction is proposed.
A Novel Transition Between Rectangular Waveguide and Layered Ridge Dielectric Waveguide

A novel transition between rectangular waveguide and Layered Ridge Dielectric Waveguide (LRDW) is reported. The transition is also suitable for use with Image Guide, Insulated Image Guide, Dielectric Ridge Waveguide and other open dielectric waveguides. Both experimental and theoretical data are presented which compare the new transition to three transitions reported in the literature.
The synthesis of 10‐fluorobenzo[a]pyrene

The synthesis of 10-fluorobenzo[a]pyrene in four steps from 11-fluoro-12-methylbenz[a]anthracene is described. A current hypothesis concerning the metabolism which is responsible for the carcinogenic activity of benzo[a]pyrene, BP, maintains that BP is converted into isomers of 7,8-dihydroxy-9,10-epoxy-7,8,9, 10-tetrahydrobenzo[a]pyrene which are the true carcinogens.1 If any of 7-,8-,9-, and 10-fluorobenzo[a]pyrenes proved carcinogenic an alternate mechanism for carcinogenesis would be required. If all four fluorinated compounds were non-carcinogenic strong support of the current hypothesis would be provided.2 Accordingly we planned to synthesize the fluoro BP compounds so that adequate testing could be carried out.
On the Spatial Distribution of Hard X-Rays from Solar Flare Loops

The aim of this paper is to investigate the spatial structure of the impulsive phase hard X-ray emission from solar flares. This work is motivated by the Yohkoh and the forthcoming High-Energy Solar Spectroscopic Imager (HESSI) observations. Summarizing past results, it is shown that the transport effects can account for the observations in inhomogeneous loop models where there is a strong field convergence and/or density enhancement at the top of the flaring loop. Scattering by plasma turbulence at the acceleration site or a pancake-type pitch-angle distribution of the accelerated electrons can also give rise to enhanced emission at the looptops. These could be a natural consequence of acceleration by plasma waves. This paper considers a general case of stochastic scattering and acceleration that leads to an isotropic pitch-angle distribution and an enhanced emission from the looptops or the acceleration site. Following the formalism developed in earlier papers, the strength and the spectrum of the radiation expected from the acceleration site and the footpoints are evaluated and their dependence on the parameters describing the acceleration process and the flare plasma are determined. The theoretical ratio of these two intensities and relative values of their spectral indices are compared with Yohkoh observations, demonstrating that the above-mentioned parameters can be constrained with such observations. It is shown that future high spatial and spectral resolution observations, for example those expected from HESSI, will be able to begin to distinguish between different models and constrain their parameters.
Sustained self-reversal in the reversed field pinch

Spontaneous reversal of the toroidal field in a reversed-field pinch as a result of low-$\ensuremath{\beta}$ (small $\frac{{J}_{\ensuremath{\perp}}}{{J}_{\ensuremath{\parallel}}}$) resisitive kink mode activity is investigated with use of a three-dimensional magnetohydrodynamics code. Helical and three-dimensional steady reversed states are obtained. In three dimensions quasisteady fluctuating states are observed above a critical value of the pinch parameter $\ensuremath{\theta}$.
Comparing Algorithms for Sorting with t Stacks in Series

We show that the left-greedy algorithm is a better algorithm than the right-greedy algorithm for sorting permutations using t stacks in series when t > 1. We also supply a method for constructing some permutations that can be sorted by t stacks in series and from this get a lower bound on the number of permutations of length n that are sortable by t stacks in series. Finally we show that the left-greedy algorithm is neither optimal nor defines a closed class of permutations for t > 2.
On the calculation of soft phase space integral

The recent discovery of the Higgs boson at the LHC attracts much attention to the precise calculation of its production cross section in quantum chromodynamics. In this work, we discuss the calculation of soft triple-emission phase space integral, which is an essential ingredient in the recently calculated soft-virtual corrections to Higgs boson production at next-to-next-to-next-to-leading order. The main techniques used this calculation are method of differential equation for Feynman integral, and integration of harmonic polylogarithms.
Gravitational wave sources containing massive black holes

Abstract Types of sources containing massive black holes (MBHs) that could be observed by the Laser Interferometer Space Antenna (LISA) will be discussed. Probably the most likely type of source is compact stars or 5 to 10 M⊙ black holes (BHs) orbiting around roughly 10 5 to 10 7 M⊙ MBHs in galactic nuclei. Another perhaps observable type is the collapse of supermassive stars to form MBHs. Other possible sources are MBH-MBH binaries formed from multiple seed MBHs grown in galactic nuclei, or formed after galaxy mergers. It appears plausible, or even likely, that one or more of the above types of binaries containing MBHs can be detected and studied by LISA.
The use of Br/Cl to promote regioselective gold-catalyzed rearrangement of propargylic carboxylates: an efficient synthesis of (1Z, 3E)-1-bromo/chloro-2-carboxy-1,3-dienes

A gold-catalyzed synthesis of 1-bromo/chloro-2-carboxy-1,3-dienes is developed using propargylic carboxylates containing halogenated alkynes as substrates. The reaction is highly diastereoselective, and the halogen atom at the alkyne terminus selectively promotes a 1,2-acyloxy migration. The diene products participate in the Diels-Alder and cross-coupling reactions.
Specificity of anion binding in the substrate pocket of bacteriorhodopsin.

The structure of the D85S mutant of bacteriorhodopsin with a nitrate anion bound in the Schiff-base binding site, and the structure of the anion-free protein have been obtained in the same crystal form. Together with the previously solved structures of this anion pump, in both the anion-free state and bromide-bound state, these new structures provide insight into how this mutant of bacteriorhodopsin is able to bind a variety of different anions in the same binding pocket. The structural analysis reveals that the main structural change that accommodates different anions is the repositioning of the polar side-chain of S85. On the basis of these x-ray crystal structures, the prediction is then made that the D85S/D212N double mutant might bind similar anions and do so over a broader pH range than does the single mutant. Experimental comparison of the dissociation constants, K{sub d}, for a variety of anions confirms this prediction and demonstrates, in addition, that the binding affinity is dramatically improved by the D212N substitution.
Preparation, reactivity, and neurotoxicity of tryptamine-4,5-dione

Abstract Tryptamine-4,5-dione protected as the carbamate was prepared in excellent overall yield by the oxidation of serotonin carbamate with benzeneseleninic anhydride. This o -quinone, which was potently neurotoxic, readily added sulfur nucleophiles under basic conditions including cysteine and glutathione in 1,4-fashion, a reactivity pattern which may reflect the mechanism of the neurotoxicity.
Electronic Flowmeter System

A flowmeter system is described which gives continuous readings of flow velocity, with a fast rate of response. The ``upstream‐downstream'' method is used in which velocity of a fluid is determined by measuring the phase difference between an upstream and downstream ultrasonic wave of, say, 100 000 cycles. The functions of the transmitting and receiving transducers are interchanged at a fast rate, say 100 cycles per second, allowing the use of a synchronous rectifier. In this way, no long time stability of the phasemeter is required so that very small flow rates can be measured. Velocities as low as 0.1 cm/sec were successfully measured. A special commutator switch with very low transfer capacitance and, as an alternative, an electronic switch are described. The transducers used are barium titanate crystals mounted in a manner so that their contact with the fluid is avoided.
BPS and non-BPS states in a supersymmetric Landau-Ginzburg theory

We analyze the spectrum of the = (2,2) supersymmetric Landau-Ginzburg theory in two dimensions with superpotential W = Xn+2−λX2. We find the full BPS spectrum of this theory by exploiting the direct connection between the UV and IR limits of the theory. The computation utilizes results from the Picard-Lefschetz theory of singularities and its extension to boundary singularities. The additional fact that this theory is integrable requires that the BPS states do not close under scattering. This observation fixes the masses of non-BPS states as well.
Nonlinear In-Plane and Out-of-Plane Vibrations in Solar Arrays

This paper presents the results of analytical investigations of nonlinear effects in in-plane and out-of-plane vibrations of solar arrays caused by surface wrinkling of solar array blankets. It is shown that nonlinearities generated by wrinkles are important even for small deformations. Approximate analytical solutions describing the frequency and damping dependencies of the amplitudes of in-plane vibrations are derived. A new phenomenon - a parametrical resonance of out-of-plane vibrations induced by in-plane vibrations - is described.
Analysis of the stabilized supralinear network

We study a rate-model neural network composed of excitatory and inhibitory neurons in which neuronal input-output functions are power laws with a power greater than 1, as observed in primary visual cortex. This supralinear input-output function leads to supralinear summation of network responses to multiple inputs for weak inputs. We show that for stronger inputs, which would drive the excitatory subnetwork to instability, the network will dynamically stabilize provided feedback inhibition is sufficiently strong. For a wide range of network and stimulus parameters, this dynamic stabilization yields a transition from supralinear to sublinear summation of network responses to multiple inputs. We compare this to the dynamic stabilization in the balanced network, which yields only linear behavior. We more exhaustively analyze the two-dimensional case of one excitatory and one inhibitory population. We show that in this case, dynamic stabilization will occur whenever the determinant of the weight matrix is positive and the inhibitory time constant is sufficiently small, and analyze the conditions for supersaturation, or decrease of firing rates with increasing stimulus contrast which represents increasing input firing rates. In work to be presented elsewhere, we have found that this transition from supralinear to sublinear summation can explain a wide variety of nonlinearities in cerebral cortical processing.
Cross-section uncertainties in the gallium neutrino source experiments

Abstract The 51 Cr neutrino source experiments play a unique role in testing overall operations of the GALLEX and SAGE solar neutrino experiments. Recently Hata and Haxton argued that the excited-state contribution to the 71 Ga cross section for 51 Cr neutrino absorption might not be known reliably, despite forward-angle (p,n) measurements. A large-basis shell model calculation reported here indicates that the unusual situation they envisioned – destructive interference between weak spin and strong spin-tensor amplitudes – does occur for the transition to the first excited state in 71 Ge. The calculation provides a counterexample to procedures previously used to determine the 51 Cr cross section: the predicted (p,n) cross section for this state agrees with experiment, while the BGT value is well outside the accepted 3 σ limit. The results argue for a shift in the interpretation of the source experiments: they become more crucial as measurements of the 71 Ga detector response to 7 Be solar neutrinos, and less definitive as wholly independent tests of 71 Ge recovery and counting efficiencies.
On Ricci flat supermanifolds

We study the Ricci flatness condition on generic supermanifolds. It has been found recently that when the fermionic complex dimension of the supermanifold is one the vanishing of the super-Ricci curvature implies the bosonic submanifold has vanishing scalar curvature. We prove that this phenomena is only restricted to fermionic complex dimension one. Further we conjecture that Calabi-Yau theorem holds for supermanifolds whose complex fermionic dimension is larger than one.
ALIGNMENT OF THE SCALAR GRADIENT IN EVOLVING MAGNETIC FIELDS

We conduct simulations of turbulent mixing in the presence of a magnetic field, grown by the small-scale dynamo. We show that the scalar gradient field, ∇C, which must be large for diffusion to operate, is strongly biased perpendicular to the magnetic field, B. This is true both early on, when the magnetic field is negligible, and at late times, when the field is strong enough to back react on the flow. This occurs because ∇C increases within the plane of a compressive motion, but B increases perpendicular to it. At late times, the magnetic field resists compression, making it harder for scalar gradients to grow and likely slowing mixing.
A Late-Time Flattening of Afterglow Light Curves

We present a sample of radio afterglow light curves with measured decay slopes that show evidence of a flattening at late times compared to optical and X-ray decay indices. The simplest origin for this behavior is that the change in slope is due to a jetlike outflow making a transition to subrelativistic expansion. This can explain the late-time radio light curves for some but not all of the bursts in the sample. We investigate several possible modifications to the standard fireball model, which can flatten late-time light curves. Changes to the shock microphysics, which govern particle acceleration, or energy injection to the shock (either radially or azimuthally) can reproduce the observed behavior. Distinguishing between these different possibilities will require simultaneous optical/radio monitoring of afterglows at late times.
An Improved Parameterized Algorithm for the Minimum Node Multiway Cut Problem

The parameterized node multiway cut problem is for a given graph to find a separator of size bounded by k whose removal separates a collection of terminal sets in the graph. In this paper, we develop an O(k4k n 3) time algorithm for this problem, significantly improving the previous algorithm of time $O(4^{k^{3}}n^{5})$for the problem. Our result gives the first polynomial time algorithm for the minimum node multiway cut problem when the separator size is bounded by O(log n).
Thieno[3,2-b]thiophene-2-carboxylic acid derivatives as GPR35 agonists

The optimization of a series of thieno[3,2-b]thiophene-2-carboxylic acid derivatives for agonist activity against the GPR35 is reported. Compounds were optimized to achieve β-arrestin-biased agonism for developing probe molecules that may be useful for elucidating the biology and physiology of GPR35. Compound 13 was identified to the most potent GPR35 agonist, and compounds 30 and 36 exhibited the highest efficacy to cause β-arrestin translocation.
Resonator Design With An Intracavity Time-Varying Index Gradient

Side-pumped lasers such as flashlamp- or reactor-pumped lasers often have a nonuniform energy deposition in the gain medium, which can establish a significant transverse index gradient. This gradient significantly complicates energy extraction. A normalized resonator analysis method is developed that predicts resonator stability transitions and mode sizes for parabolic index fields. Parameter studies for some practical classes of resonators are presented, along with some design guidelines. Experimental comparison for a long-pulse gas laser shows good agreement with stability transition times. Two resonator-design approaches are presented for increasing the extraction efficiency in the presence of intracavity index gradients.
Unavoidable parallel minors of 4-connected graphs

A parallel minor is obtained from a graph by any sequence of edge contractions and parallel edge deletions. We prove that, for any positive integer k, every internally 4-connected graph of sufficiently high order contains a parallel minor isomorphic to a variation of K4,k with a complete graph on the vertices of degree k, the k-partition triple fan with a complete graph on the vertices of degree k, the k-spoke double wheel, the k-spoke double wheel with axle, the (2k+1)-rung Mobius zigzag ladder, the (2k)-rung zigzag ladder, or Kk. We also find the unavoidable parallel minors of 1-, 2-, and 3-connected graphs. © 2008 Wiley Periodicals, Inc. J Graph Theory 60: 313-326, 2009
Link-state routing with hop-by-hop forwarding can achieve optimal traffic engineering

This paper settles an open question with a positive answer: Optimal traffic engineering (or optimal multicommodity flow) can be realized using just link-state routing protocols with hop-by-hop forwarding. Today's typical versions of these protocols, Open Shortest Path First (OSPF) and Intermediate System-Intermediate System (IS-IS), split traffic evenly over shortest paths based on link weights. However, optimizing the link weights for OSPF/IS-IS to the offered traffic is a well-known NP-hard problem, and even the best setting of the weights can deviate significantly from an optimal distribution of the traffic. In this paper, we propose a new link-state routing protocol, PEFT, that splits traffic over multiple paths with an exponential penalty on longer paths. Unlike its predecessor, DEFT, our new protocol provably achieves optimal traffic engineering while retaining the simplicity of hop-by-hop forwarding. The new protocol also leads to a significant reduction in the time needed to compute the best link weights. Both the protocol and the computational methods are developed in a conceptual framework, called Network Entropy Maximization, that is used to identify the traffic distributions that are not only optimal, but also realizable by link-state routing.
Canonical and microcanonical ensemble approaches to Bose-Einstein condensation: The thermodynamics of particles in harmonic traps

The thermodynamic properties of bosons moving in a harmonic trap in an arbitrary number of dimensions are investigated in the grand canonical, canonical and microcanonical ensembles by applying combinatorial techniques developed earlier in statistical nuclear fragmentation models. Thermodynamic functions such as the energy and specific heat are computed exactly in these ensembles. The occupation of the ground or condensed state is also obtained exactly, and signals clearly the phase transition. The application of these techniques to fermionic systems is also briefly discussed.
Resonant enhancement of dielectronic recombination by a microwave field

We have observed dielectronic recombination of ${\mathrm{Ba}}^{+}$ and ${e}^{\ensuremath{-}}$ from a continuum of finite bandwidth in the presence of microwave fields of frequencies 8.08 and 12.05 GHz and amplitudes of up to 2 V/cm. There are sharp resonant enhancements when the microwave frequency matches the $\ensuremath{\Delta}n\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1$, 2, and 3 resonances of the intermediate autoionizing Rydberg states, and we attribute the enhancements to resonant microwave Stark $\ensuremath{\ell}$ mixing. The microwave field provides a simple and powerful way to enhance the recombination rate for incident electrons of a specific energy.
FROM BEVALAC TO AGS

We describe some research efforts and results in high energy nuclear physics experiments in which the University of California, Riverside Heavy Ion Physics Group was involved. The Group was formed in 1974 by the late Robert T. Poe and the author. The pre-RHIC research spanned an energy range from 1 GeV A at the BEVALAC in LBNL to 10 GeV A at the AGS in BNL.
Guessing Secrets with Inner Product Questions

We suppose we are given some fixed (but unknown) subset X of a set Ω = &#x1d53d; n 2 , where &#x1d53d;2 denotes the field of two elements. Our goal is to learn as much as possible about the elements of X by asking certain binary questions. Each "question" Q is just some element of Ω, and the "answer" to Q is just the inner product Q . x ∈ &#x1d53d;2 for some x ∈ X. However, the choice of x is made by a truthful (but possibly malevolent) adversary A, whom we may assume is trying to choose answers so as to yield as little information as possible about X. In this note, we investigate several aspects of this problem. In particular, we are interested in extracting as much information as possible about X from A's answers. Although Acan prevent us from learning the identity of any particular element of X, with appropriate questions we can still learn quite a bit about X. We determine the maximum amount of information that can be recovered under these assumptions and describe explicit sets of questions for achieving this goal. For the c...
Molecular architecture of the Nup84–Nup145C–Sec13 edge element in the nuclear pore complex lattice

Nuclear pore complexes (NPCs) facilitate all nucleocytoplasmic transport. These massive protein assemblies are modular, with a stable structural scaffold supporting more dynamically attached components. The scaffold is made from multiple copies of the heptameric Y complex and the heteromeric Nic96 complex. We previously showed that members of these core subcomplexes specifically share an ACE1 fold with Sec31 of the COPII vesicle coat, and we proposed a lattice model for the NPC based on this commonality. Here we present the crystal structure of the heterotrimeric 134-kDa complex of Nup84-Nup145C-Sec13 of the Y complex. The heterotypic ACE1 interaction of Nup84 and Nup145C is analogous to the homotypic ACE1 interaction of Sec31 that forms COPII lattice edge elements and is inconsistent with the alternative 'fence-like' NPC model. We construct a molecular model of the Y complex and compare the architectural principles of COPII and NPC lattices.
A simple base-mediated halogenation of acidic sp2 C-H bonds under noncryogenic conditions.

A new method has been developed for in situ halogenation of acidic sp2 carbon−hydrogen bonds in heterocycles and electron-deficient arenes. Either selective monohalogenation or one-step exhaustive polyhalogenation is possible for substrates possessing several C−H bonds that are flanked by electron-withdrawing groups. For the most acidic arenes, such as pentafluorobenzene, K3PO4 base can be employed instead of BuLi for metalation/halogenation sequences.
Reclaiming Fundamental Principles of Criminal Law in the Darfur Case

According to the authors, the Report of the UN Commission of Inquiry on Darfur and the Security Council referral of the situation in Darfur to the International Criminal Court (ICC) bring to light two serious deficiencies of the ICC Statute and, more generally, international criminal law: (i) the systematic ambiguity between collective responsibility (i.e. the responsibility of the whole state) and criminal liability of individuals, on which current international criminal law is grounded, and (ii) the failure of the ICC Statute fully to comply with the principle of legality. The first deficiency is illustrated by highlighting the notions of genocide and genocidal intent, as well as that of joint criminal enterprise. The second is exposed by drawing attention to the uncertainties and ambiguities surrounding such notions as recklessness and dolus eventualis, and in addition to the frequent reliance in both international case law and the legal literature on customary international law and loose concepts such as proportionality. The authors finally point out that if the ICC tries to operate as a real criminal court under the rule of law and shows sensitivity to the rights and interests of the accused, US fears of politicized prosecution will diminish. * Cardozo Professor of Jurisprudence, Columbia University Law School; member of the Journal ’s Board of Editors; fletch@law.columbia.edu. ** Ph.D., Columbia University; J.D., Columbia University Law School; jdo18@columbia.edu. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Journal of International Criminal Justice 3 (2005),539^561 doi:10.1093/jicj/mqi049 Oxford University Press, 2005, All rights reserved. For permissions please email journals.permissions@oupjournals.org
Markov tree model of transport in area-preserving maps

Abstract Transport in an area-preserving map with a mixture of regular and chaotic regions is described in terms of the flux through invariant cantor sets called cantori. A model retaining a discrete set of cantori approaching a boundary circle gives the Markov chain description of Hanson, Cary and Meiss. The inclusion of cantori surrounding island chains, and islands about islands, etc. gives a Markov tree model with a slower decay rate. The survival probability distribution is shown to decay asymptotically as a power law. The decay exponent agrees reasonably well with the computations of Karney and of Chirikov and Shepelyanski.