cssi/SciSciGPT-SciSciNet huggingface dataset:
Augmented Space Recursion Code and Application in Simple Binary Metallic Alloy

We present here an optimized and parallelized version of the augmented space recursion code for the calculation of the electronic and magnetic properties of bulk disordered alloys, surfaces and interfaces, either flat, corrugated or rough, and random networks. Applications have been made to bulk disordered alloys to benchmark our code.
Astrometric masses of 21 asteroids, and an integrated asteroid ephemeris

We apply the technique of astrometric mass determination to measure the masses of 21 main-belt asteroids; the masses of 9 Metis (1.03 ± 0.24 × 10-11 M⊙), 17 Thetis (6.17 ± 0.64 × 10-13 M⊙), 19 Fortuna (5.41 ± 0.76 × 10-12 M⊙), and 189 Phthia (1.87 ± 0.64 × 10-14 M⊙) appear to be new. The resulting bulk porosities of 11 Parthenope (12±4%) and 16 Psyche (46±16%) are smaller than previously-reported values. Empirical expressions modeling bulk density as a function of mean radius are presented for the C and S taxonomic classes. To accurately model the forces on these asteroids during the mass determination process, we created an integrated ephemeris of the 300 large asteroids used in preparing the DE-405 planetary ephemeris; this new BC-405 integrated asteroid ephemeris also appears useful in other high-accuracy applications.
Spatially resolved evaporative patterns from water

Unexpectedly distinct patterns in evaporation were observed over heated water. Although the patterns had chaotic aspects, they often showed geometric patterns. These patterns bore strong resemblance to the infrared emission patterns observable with a mid-infrared camera focused on the water surface. This similarity puts constraints on the mechanism of evaporation, and leads to a general hypothesis as to the nature of the evaporative process.
Palladium-Catalyzed Formation of Aceanthrylenes: A Simple Method for Peri-Cyclopentenelation of Aromatic Compounds

2(PPh3)2 (4.5 mol %), PPh3 (23 mol %), CuSO4/ Al2O3 (17 mol %), alkyne (400 mol %), Et3N (400 mol %), benzene (deoxygenated), refluxed 16 h. b Total isolated yield of 2 and 3 after chromatography. c Relative ratios determined by 1H NMR. d Sealed tube reactions were carried out at 110 °C with no copper.
Non-Enzymatic Phosphate Condensation in Dilute Aqueous Media-the Effect of Alkyl Substituents on Sulfamide

Abstract The reactions of alkyl-substituted sulfamides with diphosphate and triphosphate in dilute aqueous solution are examined to determine the reaction requirements with respect to the relative position of amino hydrogens. A nucleophilic attack by the sulfamide anion on the phosphate is postulated, resulting in the cyclocondensation of triphosphate to trimetaphosphate and the formation of amidophosphates. The major reaction pathway leads to the formation of sulfamate.
Phase behavior of ditethered nanospheres

We report the results from a computational study of the self-assembly of amphiphilic ditethered nanospheres using molecular simulation. We explore the phase behavior as a function of nanosphere diameter, interaction strength, and directionality of the tether–tether interactions. We predict the formation of seven distinct ordered phases. We compare these structures with those observed in linear and star triblock copolymer systems.
Direct Calculation of the Scattering Amplitude Without Partial Wave Analysis

Two developments in scattering theory are reported. We show, in a practical way, how one can calculate the scattering amplitude without invoking a partial-wave expansion. First, the integral expression for the scattering amplitude $f(\ensuremath{\theta})$ is simplified by an analytic integration over the azimuthal angle. Second, the full scattering wave function that appears in the integral expression for $f(\ensuremath{\theta})$ is obtained by solving the Schr\"odinger equation with the finite element method. As an example, we calculate electron scattering from static hydrogen (the Hartree potential). With minimal computational effort, we obtain accurate and stable results for the scattering amplitude.
Edge coloring models and reflection positivity

Solving a conjecture of M. H. Freedman, L. Lovasz and A. Schrijver, we prove that a graph parameter is edge reflection positive and multiplicative if and only if it can be represented by an edge coloring model.
Vitamin D supplementation reduces airway hyperresponsiveness and allergic airway inflammation in a murine model

Background Asthma is a chronic disease associated with airway hyperresponsiveness (AHR), airway obstruction, and airway remodeling. NF-κB is a transcriptional factor that regulates and co-ordinates the expression of various inflammatory genes. The NF-κB subunits, p50 and Rel-A, are translocated to the nucleus by importin α3 and importin α4. There is growing evidence that vitamin D is a potent immunomodulator. However, the evidence for beneficial or adverse effects of vitamin D in asthma is still unclear.
Energy principle with global invariants

A variational principle is proposed for constructing equilibria with minimum energy in a toroidal plasma. The total energy is minimized subject to global invariants which act as constraints during relaxation of the plasma. These global integrals of motion are preserved exactly for all ideal motions and approximately for a wide class of resistive motions. We assume, specifically, that relaxation of the plasma is dominated by a tearing mode of single helicity. Equilibria with realistic current density and pressure profiles may be constructed in this theory, which is also used here to study current penetration in tokamaks. The second variation of the free energy functional is computed. It is shown that if the second variation of any equilibrium constructed in this theory is positive, the equilibrium satisfies the necessary and sufficient conditions for ideal stability.
Complementarity in contests

Abstract To facilitate the study of contests in general equilibrium, we examine winner-take-all contests in which the prize is complementary to the effort of the contestants, as inputs are in production functions or final goods in utility functions. We focus on the effects of technological factors and endowments on the effort and the welfare of the contestants. Most of our findings differ considerably from the standard model of contests in which prize and effort are independent. In particular, we find a critical role for the elasticity of substitution between prize and effort. For example, under low elasticities of substitution, a higher prize reduces the effort exerted by the contestants.
Computation of Acoustic Waves Through Sliding-Zone Interfaces

The effect of a patched sliding-zone interface on the transmission of acoustic waves is examined for two- and three-dimensional model problems. A simple but general interpolation scheme at the patched boundary passes acoustic waves without distortion, provided that a suf® ciently small time step is taken. A guideline is provided for the maximum permissible time step or zone speed that gives an acceptable error introduced by the sliding-zone interface.
Diamine ligands in copper -catalyzed reactions

The utility of copper-mediated cross-coupling reactions has been significantly increased by the development of mild reaction conditions and the ability to employ catalytic amounts of copper. The use of diamine-based ligands has been important in these advances and in this review we discuss these systems, including the choice of reaction conditions and applications in the synthesis of pharmaceuticals, natural products and designed materials.
A new facility and technique for two-dimensional aerodynamic testing

The design and operational characteristics of a new test leg for the High Reynolds Number Facility at Ames Research Center are presented, and the unique features of a test section for obtaining two-dimensional airfoil data are reviewed. The new facility operates at unit Reynolds numbers ranging from 1,000,000/ft to 30,000,000/ft. Boundary-layer suction panels are used in the test section (16 in. wide by 24 in. high) to minimize side-wall interference effects. Flexible, easily adjustable upper and lower walls allow test-channel area-ruling so as to nullify Mach-number changes induced by mass removal, to correct for longitudinal boundary-layer growth, and to provide contouring compatible with the streamlines of the model in free air.
Cheap talk and burned money

We augment the standard Crawford–Sobel (1982, Econometrica 50, 1431–1451) model of cheap talk communication by allowing the informed party to use both costless and costly messages. The issues on which we focus are the consequences for cheap talk signaling of the option to burn money and the circumstances under which both cheap talk and burned money are used to signal information.
Using auxiliary gas power for CCS energy needs in retrofitted coal power plants

Adding post-combustion capture technology to existing coal-fired power plants is being considered as a near-term option for mitigating CO2 emissions. To supply the thermal energy needed for CO2 capture, much of the literature proposes thermal integration of the existing coal plant’s steam cycle with the capture process’ stripper reboiler. This paper examines the option of using an auxiliary natural gas turbine plant to meet the energetic demands of carbon capture and compression. Three different auxiliary plant technologies were compared to integration for 90% capture from an existing, 500 MW supercritical coal plant. CO2 capture (via a monoethylamine (MEA) absorption process) and compression is simulated using Aspen Plus. Thermoflow software is used to simulate three gas plant technologies. In some circumstances, it is found that using an auxiliary natural gas turbine may make retrofits more attractive compared to using thermal integration. The most important factors affecting desirability of the auxiliary plant retrofit are the cost of natural gas, the full cost of integration, and the potential for sale of excess electricity.
Parameterizing Hecke Algebra Modules: Bernstein-Zelevinsky Multisegments, Kleshchev Multipartitions, and Crystal Graphs

This paper provides a combinatorial and representation-theoretic dictionary between three sets of objects: multisegments, multipartitions, and the irreducible modules of the affine Hecke algebra H n of type A (for generic q). The dictionary is dictated by Grojnowski's theorem [G] that gives a crystal structure on the irreducible modules of H n ,n ≥ 0. (See also [A2], [AM].) Given a Kleshchev multipartition, we construct an irreducible module as the unique simple quotient of a module induced up from smaller Hecke algebras. We compare that to Bernstein-Zelevinsky's [BZ, Z] construction of an irreducible module given a multisegment. We describe the corresponding crystal structure on multisegments and multipartitions. However, the new result here is not the explicit description of the crystal graph, but the identification of three different constructions of the irreducible modules, all of which give you the same graph when the edges are given by taking simple submodules in a restriction.
Simulation of Orbital Debris Impact on Porous Ceramic Tiles

Ceramic tiles provide lightweight, reusable insulation for spacecraft thermal protection systems but are vulnerable to orbital debris impact damage. Because a wide range of impact conditions that may be experienced in orbit cannot be duplicated in the laboratory, design for orbital debris impact effects must include analytical or numerical modeling. Recent research has developed and validated a new computational approach to the simulation of orbital debris impact on porous ceramic thermal protection systems. Simulations using the validated formulation suggest scaling rules for application in spacecraft design.
Vanishing via Lifting to Second Witt Vectors and a Proof of an Isotriviality Result

Abstract A proof based on reduction to finite fields of Esnault and Viehweg's stronger version of the Sommese vanishing theorem for k-ample line bundles is given. This result is used to give different proofs of isotriviality results of Parshin and Migliorini.
Three-Dimensional Shape Optimization with Substructuring

The substructure or superelement formulation used in the finite element technique was employed for threedimensional shape optimization problems. In a design process, one often encounters the situation that only a small part of a complex component is allowed to be modified due to considerations other than structural performance. In this case, the substructure formulation is more efficient than the full-structure finite element approach and is well suited for structural optimization, since the design process is iterative and the analysis has to be performed many times before the design is finalized. The substructure formulation is one in which only the stiffness matrix for the modified part is reformulated, reduced to the exterior degrees-of-freedom for the changed design, and can provide significant savings in computing resources. In shape optimization, the computational advantage is not only in analysis but also in the sensitivity calculations which provide in a further reduction of computing time. A front steering knuckle is used as an example to demonstrate the use and efficiency of the superelement formulation.
Cyclotron production of high purity iodine-123 for medical applications

Iodine-123 is recognized today as the best radioiodine available for use in diagnostic nuclear medicine. At UC Davis, a continuous flow method was developed and has been operational since 1974 providing high-purity123I made indirectly by means of the127I(p, 5n)123Xe→123I reaction. Targetry and radiochemical systems are described, as well as in-progress developments for total system automation. A comparison of different quality123I products is made based upon radionuclidic and dosimetry considerations. The high-purity, no-carrier-added123I produced at Crocker Nuclear Laboratory is being used in many research labeling efforts in proteins, amino acids, antibiotics, fatty acids, and hormones.
The Navier–Stokes-alpha model of fluid turbulence

Abstract We review the properties of the nonlinearly dispersive Navier–Stokes-alpha (NS-α) model of incompressible fluid turbulence — also called the viscous Camassa–Holm equations in the literature. We first re-derive the NS-α model by filtering the velocity of the fluid loop in Kelvin’s circulation theorem for the Navier–Stokes equations. Then we show that this filtering causes the wavenumber spectrum of the translational kinetic energy for the NS-α model to roll off as k−3 for kα>1 in three dimensions, instead of continuing along the slower Kolmogorov scaling law, k−5/3, that it follows for kα
Interactions between Carbon and Nitrogen Mineralization and Soil Organic Matter Chemistry in Arctic Tundra Soils

We used long-term laboratory incubations and chemical fractionation to characterize the mineralization dynamics of organic soils from tussock, shrub, and wet meadow tundra communities, to determine the relationship between soil organic matter (SOM) decomposition and chemistry, and to quantify the relative proportions of carbon (C) and nitrogen (N) in tundra SOM that are biologically available for decomposition. In all soils but shrub, we found little decline in respiration rates over 1 year, although soils respired approximately a tenth to a third of total soil C. The lack of decline in respiration rates despite large C losses indicates that the quantity of organic matter available was not controlling respiration and thus suggests that something else was limiting microbial activity. To determine the nature of the respired C, we analyzed soil chemistry before and after the incubation using a peat fractionation scheme. Despite the large losses of soil C, SOM chemistry was relatively unchanged after the incubation. The decomposition dynamics we observed suggest that tundra SOM, which is largely plant detritus, fits within existing concepts of the litter decay continuum. The lack of changes in organic matter chemistry indicates that this material had already decomposed to the point where the breakdown of labile constituents was tied to lignin decomposition. N mineralization was correlated with C mineralization in our study, but shrub soil mineralized more and tussock soil less N than would have been predicted by this correlation. Our results suggest that a large proportion of tundra SOM is potentially mineralizable, despite the fact that decomposition was dependent on lignin breakdown, and that the historical accumulation of organic matter in tundra soils is the result of field conditions unfavorable to decomposition and not the result of fundamental chemical limitations to decomposition. Our study also suggests that the anticipated increases in shrub dominance may substantially alter the dynamics of SOM decomposition in the tundra.
Energy-efficient transmission for MIMO interference channels

In previous work on multiple-input multiple-output (MIMO) interference channels, it has usually been assumed that the transmit power at each transmitter is fixed. Power is equally allocated among different streams, and MIMO beamforming is applied only to mitigate interference and improve the system performance. In this paper, we design the transmit powers, power allocation among streams, and beamforming matrices jointly for each transmit-receive pair (link) to maximize the energy efficiency in a MIMO interference channel. Centralized and decentralized energy-efficient beamforming algorithms are developed based on global and local channel state information (CSI) at each transmitter, respectively. A distributed beamforming algorithm that combines minimum mean squared error (MMSE) and two power allocation algorithms is also developed; this algorithm only requires the information of the desired link. The decentralized and distributed schemes can be combined with scheduling to achieve good performance when the interference among links cannot be canceled. Simulation results show that the proposed algorithms can achieve good performance close to the upper bound, and the decentralized algorithm can perform as well as the centralized scheme. The distributed algorithm is suboptimal, but requires much less signaling. In addition, we show that the decentralized and distributed schemes result in a fairer allocation than the centralized approach.
Bounds on expected black hole spins in inspiraling binaries

As a first step toward understanding the angular momentum evolution history of black holes in merging black hole/neutron star binaries, we perform population synthesis calculations to track the distribution of accretion histories of compact objects in such binaries. We find that there are three distinct processes that can possibly contribute to the black hole spin magnitude: a birth spin for the black hole, imparted at either (1) the collapse of a massive progenitor star to a black hole or (2) the accretion-induced collapse of a neutron star to a black hole, and (3) an accretion spin-up when the already formed black hole (via processes 1 or 2) goes through an accretion episode (through an accretion disk or a common-envelope phase). Our results show that, with regard to accretion-induced spin-up in merging BH-NS binaries (method 3 above), only accretion episodes associated with common-envelope phases and hypercritical accretion rates occur in the formation history of merging black hole/neutron star binaries. Lacking unambiguous experimental information about BH birth spins (i.e., regarding the results of processes 1 and 2), we choose two fiducial values for the BH birth angular momentum parameter a = J/M2, consistent with observations of (1) NS birth spins (a 0) and (2) X-ray binaries (a = 0.5). Using these two fiducial values and a conservative upper bound on the specific angular momentum of accreted matter, we discuss the expected range of black hole spins in the binaries of interest. We conclude with comments on the significance of these results for ground-based gravitational wave searches of inspiral signals from black hole binaries.
THREE-DIMENSIONAL STATISTICS OF RADIO POLARIMETRY

The measurement of radio polarization may be regarded as a three-dimensional statistical problem because the large photon densities at radio wavelengths allow the simultaneous detection of the three Stokes parameters that completely describe the radiation's polarization. The statistical nature of the problem arises from the fluctuating instrumental noise and possibly from fluctuations in the radiation's polarization. A statistical model is used to derive the general, three-dimensional statistics that govern radio polarization measurements. The statistics are derived for specific cases of source-intrinsic polarization, with an emphasis on the orthogonal polarization modes in pulsar radio emission. The statistics are similar to those commonly found in other fields of the physical, biological, and Earth sciences. Given the highly variable linear and circular polarization of pulsar radio emission, an understanding of the three-dimensional statistics may be an essential prerequisite to a thorough interpretation of pulsar polarization data.
eWOM and the importance of capturing consumer attention within social media

Word-of-mouth (WOM) is widely regarded as one of the most influential factors impacting consumer behavior, yet traditional models were constructed oblivious to the potential of electronic word-of-mouth (eWOM) and social media. In particular, very little is known about the dynamics affecting consumer attention within two-way many-to-many mediated environments even though attention constitutes a critical step. Thus, we construct a conceptual framework that grounds consumer attention within a larger progression of behavioral responses to eWOM. We then conduct an experiment (n = 28) that isolates contextual antecedents of attention to positive, negative, and neutral WOM for both luxury and non-luxury brands within a social media platform. Using behavioral eye-tracking, we find that WOM message valence interacts with brand type to affect attention differently. Implications of these findings for facilitating eWOM are discussed with future research directions suggested.
Field Shaping to Improve Vacuum Diode Voltage Holdoff

In our work we need a small vacuum diode which will reliably hold off a pulse voltage in excess of 150 kV. These diodes typically have an interelectrode spacing of 6 to 10 mm with a glass insulator length 3 to 4 times the interelectrode spacing. We found that the overall holdoff voltage for a diode with a fixed insulator and interelectrode gap length was strongly affected by the position of the interelectrode gap. The highest voltage holdoff was obtained when the interelectrode space was at the negative end of the insulator. Experiments were made with two sizes of diodes, varying the location of the interelectrode space from the negative end to the positive end. The large diode high voltage holdoff ranged from 240 kV with the interelectrode space at the negative end to a minimum of 50 kV in the middle and returning to a 180 kV with the interelectrode space at the positive end. The smaller diode high voltage holdoff ranged from a high of 200 kV with the interelectrode space at the negative end to 130 kV with the interelectrode space at the positive end. The minimum at the middle was not as pronoucned in this diode. Since most of the HV breakdowns were across the glass insulator, electron avalanching was suspected. Computer-generated field plots confirmed this possibility.
TWO POPULATIONS OF MOLECULAR CLOUDS IN THE ANTENNAE GALAXIES

Super star clusters-extremely massive clusters found predominately in starburst environments-are essential building blocks in the formation of galaxies and thought to dominate star formation in the high-redshift universe. However, the transformation from molecular gas into these ultracompact star clusters is not well understood. To study this process, we used the Submillimeter Array and the Plateau de Bure Interferometer to obtain high angular resolution ({approx}1.''5 or 160 pc) images of the Antennae overlap region in CO(2-1) to search for the molecular progenitors of the super star clusters. We resolve the molecular gas distribution into a large number of clouds, extending the differential cloud mass function down to a 5{sigma} completeness limit of 3.8 Multiplication-Sign 10{sup 5} M{sub Sun }. We identify a distinct break in the mass function around log M{sub mol}/M{sub Sun} Almost-Equal-To 6.5, which separates the molecular clouds into two distinct populations. The smaller, less massive clouds reside in more quiescent areas in the region, while the larger, more massive clouds cluster around regions of intense star formation. A broken power-law fit to the mass function yields slopes of {alpha} = -1.39 {+-} 0.10 and {alpha} = -1.44 {+-} 0.14 for the low- and high-mass cloud population, well matchedmore » to the mass function found for super star clusters in the Antennae galaxies. We find large velocity gradients and velocity dispersions at the locations of intense star formation, suggestive of compressive shocks. It is likely that these environmental factors contribute to the formation of the observed massive molecular clouds and super star clusters in the Antennae galaxies.« less
Multi-scale, multi-resolution brain cancer modeling

In advancing discrete-based computational cancer models towards clinical applications, one faces the dilemma of how to deal with an ever growing amount of biomedical data that ought to be incorporated eventually in one form or another. Model scalability becomes of paramount interest. In an effort to start addressing this critical issue, here, we present a novel multi-scale and multi-resolution agent-based in silico glioma model. While 'multi-scale' refers to employing an epidermal growth factor receptor (EGFR)-driven molecular network to process cellular phenotypic decisions within the micro-macroscopic environment, 'multi-resolution' is achieved through algorithms that classify cells to either active or inactive spatial clusters, which determine the resolution they are simulated at. The aim is to assign computational resources where and when they matter most for maintaining or improving the predictive power of the algorithm, onto specific tumor areas and at particular times. Using a previously described 2D brain tumor model, we have developed four different computational methods for achieving the multi-resolution scheme, three of which are designed to dynamically train on the high-resolution simulation that serves as control. To quantify the algorithms' performance, we rank them by weighing the distinct computational time savings of the simulation runs vs. the methods' ability to accurately reproduce the high-resolution results of the control. Finally, to demonstrate the flexibility of the underlying concept, we show the added value of combining the two highest-ranked methods. The main finding of this work is that by pursuing a multi-resolution approach, one can reduce the computation time of a discrete-based model substantially while still maintaining a comparably high predictive power. This hints at even more computational savings in the more realistic 3D setting over time, and thus appears to outline a possible path to achieve scalability for the all-important clinical translation.
Impacts of water reallocation: A combined computable general equilibrium and recreation demand model approach

To date, the regional economics literature has neglected to combine a county-level dynamic computable general equilibrium (CGE) model with a recreation demand model to analyze the temporal effects of reallocating water from agriculture to recreational use. This study begins to address this weakness in the literature by considering water reallocation issues in rural Nevada. By combining a recreation demand model with a CGE model, this study analyzes the policy effects on both the agricultural sectors and the recreation-related sectors. Model results show that the increase in non-agricultural output does not offset the reduction in agricultural output due to water withdrawal.
Perfect Codes and Balanced Generalized Weighing Matrices, II

In a previous paper, the authors proved that any set of representatives of the distinct 1-dimensional subspaces in the dual code of the unique linear perfect single-error-correcting code of length (qd?1)/(q?1) over GF(q) is a balanced generalized weighing matrix over the multiplicative group of GF(q). Moreover, this matrix was characterized as the unique (up to monomial equivalence) weighing matrix for the given parameters with minimum q-rank. We now relate these matrices to m-sequences (that is, linear shift register sequences of maximal period) by giving an explicit description in terms of the trace function; in this way, we show that a simple modification of our method can be used to obtain the matrices which are given by the “classical,” more involved construction going back to Berman. Moreover, further modifications of our matrices actually yield a wealth of monomially inequivalent examples, namely matrices for many different q-ranks.
Crystal structure and electronic structure of NbxTa2−xS (x≈0.95): A new layered compound in ternary Ta-Nb-S system

Abstract During the continuing study of the metal-rich region of the ternary Ta-Nb-S system a new layered compound, Nb x Ta 2− x S ( x ≈0.95), was found using the arc-melting method and characterized by means of X-ray diffraction experiments. The compound crystallizes in the tetragonal space group P 4/ nmm with unit cell dimensions α =333.04(7) pm and c =909.28(94) pm. The tetragonal cell contains two formula units. The structure contains homoatomic layers sequenced S-M2-M1-M1-M2-S (M is a Nb, Ta mixture) generating six-layer sheets stacked along [001] and is closely related to b.c.c. Weak S-S interactions at 319 pm between sheets contrast with the M-M binding within and between the sheets, the former presumably being responsible for the observed graphitic slippage of the samples. Based upon extended Huckel band calculations metallic properties can be expected for this compound. The relative preference of the metal sites for the two metal elements (Ta, Nb) is explained by band calculations.
Use of Conjugated Dienones in Cyclialkylations: Total Syntheses of Arucadiol, 1,2-Didehydromiltirone, (±)-Hinokione, (±)-Nimbidiol, Sageone, and Miltirone†

Functionalized hydrophenanthrenes can be prepared using a cyclialkylation-based strategy. These annulations are highly dependent on the directing effects of the arene substitutents and on conformational considerations. The utility of this methodology was featured in the syntheses of six diterpenoids.
Synthesis and transformations of D-glucuronic and L-iduronic acid glycals

Abstract d -Glucuronic acid glycals can be efficiently synthesized from diacetone glucose or tri- O -acetyl glycal and can be transformed into d -glucuronic acid donors and acceptors in high yields. Base catalyzed epimerization of d -glucuronic acid glycals provides access to the corresponding l -iduronic acid glycals. Both d -glucuronic and l -iduronic acid glycals were transformed into glycosylating agents for use in the synthesis of glycosaminoglycan oligosaccharides.
Temperature crossovers in cuprates

We study the temperature crossovers seen in the magnetic and transport properties of cuprates using a nearly antiferromagnetic Fermi-liquid model (NAFLM). We distinguish between underdoped and overdoped systems on the basis of their low-frequency magnetic behaviour and so classify the optimally doped cuprates as a special case of the underdoped cuprates. For the overdoped cuprates, we find, in agreement with earlier work, mean-field z = 2 behaviour of the magnetic variables associated with the fact that the damping rate of their spin fluctuations is essentially independent of temperature, while the resistivity exhibits a crossover from Fermi-liquid behaviour at low temperature to linear-in-T behaviour above a certain temperature . We demonstrate that above the proximity of the quasiparticle Fermi surface to the magnetic Brillouin zone boundary brings about the measured linear-in-T resistivity. For the underdoped cuprates we argue that the sequence of crossovers identified by Barzykin and Pines in the low-frequency magnetic behaviour (from mean-field z = 2 behaviour at high temperatures, , to non-universal z = 1 scaling behaviour at intermediate temperatures, , to pseudogap behaviour below ) reflects the development in the electronic structure of a precursor to a spin-density-wave state. This development begins at with a thermal evolution of the quasiparticle spectral weight which brings about temperature-dependent spin damping and ends at where the Fermi surface has lost pieces near corners of the magnetic Brillouin zone. For the resistivity is linear in T because this change in spectral weight does not affect the resistivity significantly; below vertex corrections act to bring about the measured downturn in and approximately quadratic-in-T resistivity for .
Classical and Sobolev orthogonality of the nonclassical Jacobi polynomials with parameters $$\alpha =\beta =-1$$

In this paper, we consider the second-order differential expression $$\begin{aligned} \ell [y](x)=(1-x^{2})(-(y^{\prime }(x))^{\prime }+k(1-x^{2})^{-1} y(x))\quad (x\in (-1,1)). \end{aligned}$$ This is the Jacobi differential expression with nonclassical parameters $$\alpha =\beta =-1$$ in contrast to the classical case when $$\alpha ,\beta >-1$$ . For fixed $$k\ge 0$$ and appropriate values of the spectral parameter $$\lambda ,$$ the equation $$\ell [y]=\lambda y$$ has, as in the classical case, a sequence of (Jacobi) polynomial solutions $$\{P_{n}^{(-1,-1)} \}_{n=0}^{\infty }.$$ These Jacobi polynomial solutions of degree $$\ge 2$$ form a complete orthogonal set in the Hilbert space $$L^{2}((-1,1);(1-x^{2})^{-1})$$ . Unlike the classical situation, every polynomial of degree one is a solution of this eigenvalue equation. Kwon and Littlejohn showed that, by careful selection of this first-degree solution, the set of polynomial solutions of degree $$\ge 0$$ are orthogonal with respect to a Sobolev inner product. Our main result in this paper is to construct a self-adjoint operator $$T$$ , generated by $$\ell [\cdot ],$$ in this Sobolev space that has these Jacobi polynomials as a complete orthogonal set of eigenfunctions. The classical Glazman–Krein–Naimark theory is essential in helping to construct $$T$$ in this Sobolev space as is the left-definite theory developed by Littlejohn and Wellman.
The postulates of gravitational thermodynamics.

The general principles and logical structure of a thermodynamic formalism that incorporates strongly self-gravitating systems are presented. This framework generalizes and simplifies the formulation of thermodynamics developed by Callen. The definition of extensive variables, the homogeneity properties of intensive parameters, and the fundamental problem of gravitational thermodynamics are discussed in detail. In particular, extensive parameters include quasilocal quantities and are naturally incorporated into a set of basic general postulates for thermodynamics. These include additivity of entropies (Massieu functions) and the generalized second law. Fundamental equations are no longer homogeneous first-order functions of their extensive variables. It is shown that the postulates lead to a formal resolution of the fundamental problem despite nonadditivity of extensive parameters and thermodynamic potentials. Therefore, all the results of (gravitational) thermodynamics are an outgrowth of these postulates. The origin and nature of the differences with ordinary thermodynamics are analyzed. Consequences of the formalism include the (spatially) inhomogeneous character of thermodynamic equilibrium states, a reformulation of the Euler equation, and the absence of a Gibbs-Duhem relation.
Baryon number and strangeness: signals of a deconfined antecedent

The correlation between baryon number and strangeness is used to discern the nature of the deconfined matter produced at vanishing chemical potential in high-energy nuclear collisions at the BNL RHIC. Comparisons of results of various phenomenological models with correlations extracted from lattice QCD calculations suggest that a quasi-particle picture applies. At finite baryon densities, such as those encountered at the CERN SPS, it is demonstrated that the presence of a first-order phase transition and the accompanying development of spinodal decomposition would significantly enhance the number of strangeness carriers and the associated fluctuations.
Missing Gains from Trade

The theoretical result that there are gains from trade is a central tenet of international economics. Assuming perfect competition and no market failures, trade acts like a technological improvement that expands the set of feasible allocations and enables Pareto superior outcomes to be achieved. A recent body of research has sought to quantify the magnitude of these welfare gains. In a class of standard trade models that satisfy a constant elasticity “gravity equation,” the welfare gains from trade can be computed using only aggregate data: the open economy domestic trade share and the elasticity of trade with respect to variable trade costs (see Arkolakis, Costinot, and Rodriguez-Clare 2012). One of the main findings from this literature is that the welfare gains from trade are relatively modest. For example, in a study of 19 OECD countries, Eaton and Kortum (2002) find that the welfare cost of moving to autarky ranges from 0.2–10.3 percent. Many extensions to this quantitative approach have been considered, including the introduction of input-output linkages (e.g., Caliendo and Parro 2012) and multiple sectors (e.g., Ossa 2012). Some of these extensions can substantially increase the predicted welfare gains from trade, as surveyed in Costinot and RodriguezClare (forthcoming), which reports a range of potential values for the welfare gains from trade. In this paper, we suggest a channel for welfare gains that the standard quantitative approach
A Professional Life in the History of Science

It was with some compunction that I acceded to the flattering invitation from Donald Yerxa, editor of Historically Speaking, to write of a professional life in the field of my specialty. Reluctance was the greater in that I had already given an account of that career in Isis on the occasion of the 75th anniversary of the History of Science Society in 1999. In all probability, however, there is little if any overlap between subscribers to Isis and those to Historically Speaking. That such should be the case is one of the situations discussed. Anyone who consults the earlier essay will find that it turns on personal and institutional factors. I tried not to repeat myself more than was necessary to make what follows intelligible, and ventured instead to offer some reflections on the context of my work in relation to the development of the historiography of science.
Differential binding and dopamine uptake activity of cocaine analogues modified at nitrogen

Abstract Syntheses of a variety of new N-modified cocaine analogues are reported together with their binding affinities and dopamine uptake inhibition activities. Compounds 3 and 13, which exhibit discrepancies in their binding and uptake potencies, were tested for their ability to antagonize cocaine's inhibition of dopamine reuptake.
Enforcing security in semantics driven policy based networks

Security is an important requirement in scenarios such as mobile computing that allow users to make meaningful ad hoc collaborations. Traditional security solutions are not feasible for these scenarios due to the varying nature of the collaborations. We propose an extensible framework that takes the semantics of the collaboration into account and uses semantics driven policies for enforcing security. Our policies are rooted in semantic web languages which make them amenable to interoperability and high level reasoning. We describe our policy based network that exploits packet content semantics to secure enterprise networks and the BGP routing process.
Comparison of Linear Estimators Using Pitman's Measure of Closeness

Abstract A method is given for the comparison of two linear forms of a common random vector under the criterion of Pitman's measure of closeness. Assuming multivariate normality of the random vector, one can determine exact expressions for the closeness probabilities. The applicability of the theory is illustrated on the comparison of ridge regression estimators.
Global Seismic Oscillations in Soft Gamma Repeaters

There is evidence that soft gamma repeaters (SGRs) are neutron stars that experience frequent starquakes, possibly driven by an evolving, ultrastrong magnetic field. The empirical power-law distribution of SGR burst energies, analogous to the Gutenberg-Richter law for earthquakes, exhibits a turnover at high energies, consistent with a global limit on the crust fracture size. With such large starquakes occurring, the significant excitation of global seismic oscillations (GSOs) seems likely. Moreover, GSOs may be self-exciting in a stellar crust that is strained by many randomly oriented stresses. We explain why low-order toroidal modes, which preserve the shape of the star and have observable frequencies as low as ~30 Hz, may be especially susceptible to excitation. We estimate the eigenfrequencies as a function of stellar mass and radius, as well as their magnetic and rotational shiftings/splittings. We also describe ways in which these modes might be detected and damped. There is marginal evidence for 23 ms oscillations in the hard initial pulse of the 1979 March 5 event. This could be due to the 3t0 mode in a neutron star with B ~1014 G or less, or it could be the fundamental toroidal mode if the field in the deep crust of SGR 0526-66 is ~4 × 1015 G, in agreement with other evidence. If confirmed, GSOs would give corroborating evidence for crust-fracturing magnetic fields in SGRs: B 1014 G.
Cancer of the breast and reproductive tract in relation to use of oral contraceptives

Effects of oral contraception on cancers of the female breast and reproductive tract are critically reviewed from human studies reported since 1980. The cumulative risk of breast cancer through 59 years of age appears to bear no relationship to oral contraceptive (OC) use whatsoever. Studies restricted to women under age 45, however, raise concern about a possible adverse effect from OC use before a first-term pregnancy. A duration-related protective effect against endometrial cancer occurs from use of combined OCs. The risk is reduced by about 40% with 2 years of use, and by about 60% with 4 or more years of oral contraception. Oral contraception in excess of 3 years protects against ovarian cancer. Four years of use confers a 50% reduction in risk and 7 or more years of use confers a 60%-80% reduction in ovarian cancer risk. Studies of cervical dysplasia and carcinoma in situ suggest elevated risks with 2 or more years of OC use, although results are difficult to interpret in view of numerous factors that might distort the findings. The risk of invasive cervical cancer appear to be unaffected by up to 5 years of oral contraception. Beyond this, there is evidence suggesting an elevated risk which approaches a 2-fold increase at 10 years of use. Cancers of the vagina and fallopian tube are extremely rare. Their risks have yet to be characterized in relation to oral contraception.
Radiative Torques on Interstellar Grains. II. Grain Alignment

Radiative torques on irregular dust grains, in addition to producing superthermal rotation, play a direct dynamical role in the alignment of interstellar dust with the local magnetic field. The equations governing the orientation of spinning, precessing grains are derived; H2 formation torques and paramagnetic dissipation are included in the dynamics. Stationary solutions (constant alignment angle and spin rate) are found; these solutions may be stable ("attractors") or unstable ("repellors"). The equations of motion are numerically integrated for three exemplary irregular grain geometries, exposed to anisotropic radiation with the spectrum of interstellar starlight. The resulting "trajectory maps" are classified as "noncyclic," "semicyclic," or "cyclic," with examples of each given. We find that radiative torques result in rapid grain alignment, even in the absence of paramagnetic dissipation. It appears that radiative torques due to starlight can account for the observed alignment of interstellar grains with the Galactic magnetic field.
Molecular dynamics simulations of a nucleosome and free DNA.

Abstract All atom molecular dynamics simulations (10ns) of a nucleosome and of its 146 basepairs of DNA free in solution have been conducted. DNA helical parameters (Roll, Tilt, Twist, Shift, Slide, Rise) were extracted from each trajectory to compare the conformation, effective force constants, persistence length measures, and fluctuations of nucleosomal DNA to free DNA. The conformation of DNA in the nucleosome, as determined by helical parameters, is found to be largely within the range of thermally accessible values obtained for free DNA. DNA is found to be less flexible on the nucleosome than when free in solution, however such measures are length scale dependent. A method for disassembling and reconstructing the conformation and dynamics of the nucleosome using Fourier analysis is presented. Long length variations in the conformation of nucleosomal DNA are identified other than those associated with helix repeat. These variations are required to create a proposed tetrasome conformation or to qualita...
Forced Versus Voluntary Dividend Reduction: An Agency Cost Explanation

We examine whether the agency cost arising from shareholder-bondholder conflict is an important determinant of the timing of dividend reduction decisions. Firms forced to reduce dividends owing to bond covenant violations experience lower earnings, more frequent losses, and greater earnings declines around the dividend reduction year than do firms that voluntarily reduce dividends. Relative to voluntary-reduction firms, forced-reduction firms have higher debt-to-equity ratios and managerial holdings. These findings coupled with the increased dividend payout ratios and lower announcement period returns suggest that financially distressed firms that anticipate poor performance have greater incentives to delay reducing dividends to avoid a wealth transfer to bondholders.
Floating Gate Synapses With Spike-Time-Dependent Plasticity

This paper describes a single transistor floating-gate synapse device that can be used to store a weight in a nonvolatile manner, compute a biological EPSP, and demonstrate biological learning rules such as Long-Term Potentiation, LTD, and spike-time dependent plasticity. We also describe a highly scalable architecture of a matrix of synapses to implement the described learning rules. Parameters for weight update in the 0.35 um process have been extracted and can be used to predict the change in weight based on time difference between pre- and post-synaptic spike times.
MONOGAMY OF ENTANGLEMENT, N-REPRESENTABILITY PROBLEMS AND GROUND STATES

Monogamy of entanglement is a quantum mechanical property that limits quantum correlations shared among many parties. In an example strongly interacting spin system we examine approaches for approximating the ground state energy both from above and below by mean-field and N-representability methods, respectively. Due to strong competition among the terms in the Hamiltonian, the resulting ground-state wavefunction, although is entangled, does not possess entanglement that is proportional to the system size, thus obeying the monogamy of entanglement.