cssi/SciSciGPT-SciSciNet huggingface dataset:
Simple, efficient protocols for the Pd-catalyzed cross-coupling reaction of aryl chlorides and dimethylamine

Simple and efficient procedures for the Pd-catalyzed cross-coupling reaction of aryl chlorides and dimethylamine are described. At room temperature with a strong base, t-BuXPhos is employed as the supporting ligand; at 110 °C with a weak base, XPhos is employed as the supporting ligand. In each of these cases, commercially available solutions constitute the source of the dimethylamine, and recently disclosed precatalysts constitute the source of the ligand and Pd. This work further expands the utility of these precatalysts in reactions that benefit from an easily activated source of L(1)Pd(0).
Simulations of Shocked Methane Including Self-consistent Semiclassical Quantum Nuclear Effects*

A methodology is described for atomistic simulations of shock-compressed materials that incorporates quantum nuclear effects on the fly. We introduce a modification of the multi-scale shock technique (MSST) that couples to a quantum thermal bath described by a colored noise Langevin thermostat. The new approach, which we call QB-MSST, is of comparable computational cost to MSST and self-consistently incorporates quantum heat capacities and Bose-Einstein harmonic vibrational distributions. As a first test, we study shock-compressed methane using the ReaxFF potential. The Hugoniot curves predicted from the new approach are found comparable with existing experimental data. We find that the self-consistent nature of the method results in the onset of chemistry at 40% lower pressure on the shock Hugoniot than observed with classical molecular dynamics. The temperature change associated with quantum heat capacity is determined to be the primary factor in this shift.
Relationship between maternal age and aneuploidy in in vitro fertilization pregnancy loss

Abstract Objective To determine the fetal loss rate after documented fetal cardiac activity (7-week sonogram) and to evaluate the chromosomal makeup of these losses in IVF pregnancies. Design Retrospective analysis. Setting University-based IVF center. Patient(s) Two thousand fourteen consecutive IVF pregnancies with documented fetal cardiac activity. Main outcome measure(s) Miscarriage rates and karyotypes of pregnancy losses were analyzed. Result(s) The overall pregnancy loss rate after demonstrated fetal cardiac activity was 11.6% (233/2014). A highly significant increase in fetal loss with advancing maternal age was observed ( Conclusion(s) Pregnancy loss after documentation of fetal cardiac activity is >10%. This loss is significantly increased with advancing maternal age. The major underlying cause of these losses seems to be chromosomal aneuploidy.
Addition of dimethyloxosulfonium methylide to enantiomerically pure sulfinimines: Asymmetric synthesis of 2-substituted aziridines

Abstract Diastereoselective addition of dimethyloxosulfonium methylide to chiral nonracemic pure sulfinimines 1 affords N-sulfinyl aziridines 3 in 58–70% de which are readily separated. The N-sulfinyl auxiliary in 3 was removed, without ring-opening, by treatment with MeLi.
Microstructural characterization of Ti-6Al-4V subjected to fretting

This study is focused on characterization of microstructural changes linked to deformation and crack formation mechanisms in duplex Ti-6Al-4V specimens used in displacement controlled fretting-only experiments. In particular, the effect of slip displacement amplitude and number of fretting cycles on the evolution of grain morphology, grain orientation, misorientation distribution, composition, and microhardness is investigated using electron backscatter diffraction (EBSD), energy dispersive X-ray analysis (EDX), and nanoindentation. A strong basal microtexture and significant oxygen diffusion were observed in the Ti-6Al-4V specimen that exhibited the most significant cracking. A critical slip amplitude threshold may exist for which a combination of mechanisms, such as plastic deformation, grain reorientation, and oxygen diffusion, occur during fretting that make conditions ideal for crack formation. The results provide insights for development and validation of computational crystal plasticity models with application to fretting and sliding contact problems. New fretting damage-assessment measures have also been identified and have application for components that suffer from fretting wear and/or fatigue related failures.
Modeling without representation

How can mathematical models which represent the causal structure of the world incompletely or incorrectly have any scientific value? I argue that this apparent puzzle is an artifact of a realist emphasis on representation in the philosophy of modeling. I offer an alternative, pragmatic methodology of modeling, inspired by classic papers by modelers themselves. The crux of the view is that models developed for purposes other than explanation may be justified without reference to their representational properties.
Using multirail networks in high‐performance clusters

Using multiple independent networks (also known as rails) is an emerging technique which is being used to overcome bandwidth limitations and enhance fault tolerance of current high-performance parallel computers. In this paper, we present and analyze various algorithms to allocate multiple communication rails, including static and dynamic allocation schemes. An analytical lower bound on the number of rails required for static rail allocation is shown. We also present an extensive experimental comparison of the behavior of various algorithms in terms of bandwidth and latency. We show that striping messages over multiple rails can substantially reduce network latency, depending on average message size, network load and allocation scheme. The methods compared include a static rail allocation, a basic round-robin rail allocation, a local-dynamic allocation based on local knowledge and a dynamic rail allocation that reserves both communication endpoints of a message before sending it. The last method is shown to perform better than the others at higher loads: up to 49% better than local-knowledge allocation and 37% better than the round-robin allocation. This allocation scheme also shows lower latency and it saturates at higher loads (for long enough messages). Most importantly, this proposed allocation scheme scales well with the number of rails and message size. In addition we propose a hybrid algorithm that combines the benefits of the local-dynamic allocation for short messages with those of the dynamic algorithm for large messages. Copyright © 2003 John Wiley & Sons, Ltd.
Maxwell-Chern-Simons Theory in Covariant and Coulomb Gauges

Abstract We quantize quantum electrodynamics in 2+1 dimensions coupled 2+1 to a Chern-Simons (CS) term and a charged spinor field, in covariant gauges and in the Coulomb gauge. The resulting Maxwell-Chern-Simons (MCS) theory describes charged fermions interacting with each other and with topologically massive propagating photons. We impose Gauss's law and the gauge conditions and investigate their effect on the dynamics and on the statistics ofn-particle states. We construct charged spinor states that obey Gauss's law and the gauge conditions and transform the theory to representations in which these states constitute a Fock space. We demonstrate that, in these representations, the nonlocal interactions between charges and between charges and transverse currents—along with the interactions between currents and massive propagating photons—are identical in the different gauges we analyze in this and in earlier work. We construct the generators of the Poincare group, show that they implement the Poincare algebra, and explicitly demonstrate the effect of rotations and Lorentz boosts on the particle states. We show that the imposition of Gauss's law does not produce any "exotic" fractional statistics. In the case of the covariant gauges, this demonstration makes use of unitary transformations that provide charged particles with the gauge fields required by Gauss's law, but that leave the anticommutator algebra of the spinor fields untransformed. In the Coulomb gauge, we show that the anticommutators of the spinor fields apply to the Dirac-Bergmann constraint surfaces, on which Gauss's law and the gauge conditions obtain. We examine MCS theory in the large CS coupling constant limit, and compare that limiting form with CS theory, in which the Maxwell kinetic energy term is not included in the Lagrangian 11.10.Ef, 03.70.+k, 11.15.−q.
Repeated formation of fluid threads in breakup of a surfactant-covered jet

Breakup of thin threads is widely observed in nature and technology. As a surfactant-covered liquid jet approaches breakup, its profile consists of a periodic pattern of drops connected by thin threads. Near the locations where the threads join the drops, simulations show that a series of thinner threads arise as the jet breaks. That threads can continue to form repeatedly without addition of noise when surfactants are present is unexpected based on earlier studies of surfactant-free systems. Thinning dynamics of successive threads are shown to be self-similar and approach Eggers's universal solution for clean interfaces.
Telecommunications policy in the new South Africa: participatory politics and sectoral reform

This article examines the process of telecommunications reform in the `new' South Africa. In many, if not most countries, telecommunications reform has been pushed by political and economic elites, whose ability to bring about policy transformations derives largely from the insulation of `reform' from normal political decision-making channels and distributive claims. In marked contrast, telecommunications reform in South Africa was conducted within a democratizing context and was itself a democratic process of a unique, participatory kind. The tension between participatory and electoral democracy was, for the most part, productive of a viable and legitimate reform policy.
Are policy platforms capitalized into equity prices? Evidence from the Bush/Gore 2000 Presidential Election

Abstract This paper tests for the capitalization of policy platforms into equity prices using a sample of 70 firms favored under Bush or Gore platforms during the 2000 U.S. Presidential Election. Two sources of daily data during the six months leading up to the election are incorporated: firm-specific equity returns and the probability of a Bush victory as implied by prices from the Iowa Electronic Market. For this group of politically sensitive firms, the daily baseline estimates demonstrate that platforms are capitalized into equity prices: under a Bush administration, relative to a counterfactual Gore administration, Bush-favored firms are worth 3% more and Gore-favored firms are worth 6% less, implying a statistically significant differential return of 9%. Estimates based on weekly returns are even stronger, suggesting a differential return of 16%. The most sensitive sectors include tobacco, worth 13% more under a favorable Bush administration, Microsoft competitors, worth 15% less under an unfavorable Bush administration, and alternative energy companies, worth 16% less under an unfavorable Bush administration. A corresponding analysis of campaign contributions, which allows for heterogeneity in the importance of policy platforms to the firms, supports the baseline estimates.
Symmetrical “I”-Shaped Hyperbranched Structural-Repeating-Unit (SRU) Polymers: Converting Unregistrable SRUs to SRUs Registrable by Chemical Abstracts Service's Registry System

SCION is a DuPont proprietary database that operates by use of Chemical Abstracts Service's Registry System (CASRS) for substance registration and Messenger software for searching. The CASRS cannot register structural repeating unit (SRU) (i.e., structure-based) polymers with odd numbers of crossing bonds (bonds that cross limiting parentheses or brackets). This paper describes the intellectual conversion of SRUs with an odd number of crossing bonds into hyperbranched, “I”-shaped SRUs with an even number of crossing bonds, so that they can be registered by the CASRS. A new nomenclature system is described for these new SRUs. This paper also includes conversion of other SRUs with even or odd numbers of crossing bonds but incorrect atom ratios, e.g., silsesquioxanes and poly-1,1,2,2-ethanediylidenetetraoxy.
The Neutron star and black hole initial mass function

Using recently calculated models for massive stellar evolution and supernovae coupled to a model for Galactic chemical evolution, neutron star and black hole birth functions (number of neutron stars and black holes as a function of their mass) are determined for the Milky Way galaxy. For these stars that explode as Type II supernovae, the models give birth functions that are bimodal with peaks at 1.27 and 1.76 {ital M}{sub {circle_dot}} and average masses within those peaks of 1.28 and 1.73 {ital M}{sub {circle_dot}}. For these stars that explode as Type Ib there is a narrower spread of remnant masses, the average being 1.32 {ital M}{sub {circle_dot}}, and less evidence for bimodality. These values will be increased, especially in the more massive Type II supernovae, if significant accretion continues during the initial launching of the shock, and the number of heavier neutron stars could be depleted by black hole formation. The principal reason for the dichotomy in remnant masses for Type II is the difference in the presupernova structure of stars above and below 19 {ital M}{sub {circle_dot}}, the mass separating stars that burn carbon convectively from those that produce less carbon and burn radiatively. The Type Ib{close_quote}s and themore » lower mass group of the Type II{close_quote}s compare favorably with measured neutron star masses, and in particular to the Thorsett {ital et} {ital al}. (1993) determination of the average neutron star mass in 17 systems; 1.35{plus_minus}0.27 {ital M}{sub {circle_dot}}. Variations in the exponent of a Salpeter initial mass function are shown not to affect the locations of the two peaks in the distribution function, but do affect their relative amplitudes. Sources of uncertainty, in particular placement of the mass cut and sensitivity to the explosion energy, are discussed, and estimates of the total number of neutron stars and black holes in the Galaxy are given. (Abstract Truncated)« less
Blindness: Its Relation to Age of Menarche

Blindness in human females is associated with an age of menarche which is earlier than normal. When blindness is accompanied by a total loss of light perception, menarche is even earlier.
Alkali compounds and copper chromite as low-temperature slurry phase methanol catalysts

Abstract A slurry phase synthesis of methanol via methyl formate in a single reactor at low temperatures (100–180°C) is discussed. Mixed catalyst systems comprised of alkali compounds (such as the hydroxide, formate, carbonate and bicarbonate) or alkali earth compounds and copper chromite as well as copper chromites impregnated with alkali have been found to be active for methanol synthesis. All the starting alkali compounds are converted by copper chromite to the corresponding alkali methoxide in solution. At low alkali methoxide loadings charged to the reactor, methanol formation increases with increasing methyl formate concentration while at higher loadings decreased rates of methanol synthesis are found, possibly due to blockage of hydrogenolysis sites on the copper chromite surface.
Pressure-induced reentrant phase behavior in the poly(N-vinyl-2-pyrrolidone)-water system.

Phase separation and dynamic light scattering experiments were performed on aqueous solutions of poly(N-vinyl-2-pyrrolidone) under high pressure conditions to help elucidate the role that hydrogen bonding plays in the solution behavior of water-soluble polymers. From the pressure-induced phase separation experiments we observe reentrant phase behavior in the pressure-temperature plane at fixed composition. Variation of the phase separation pressure with both composition and molecular weight is also investigated. The concentration dependence on the phase separation pressure is weak and the molecular weight dependence exhibits an approximately ${\mathit{M}}_{\mathit{w}}^{\mathrm{\ensuremath{-}}1/2}$ scaling. All this behavior can be explained through a modified Flory-Huggins theory that includes the effect of pressure and temperature on hydrogen bonds and the hydrophobic interactions. We use our data to derive fit parameters for this model and the results suggest that not only does the hydrogen bond weaken at high pressure but hydrophobic interactions increase. Dynamic light scattering (DLS) experiments on solutions within the one-phase region of the phase diagram quantify the influence of changing solvent quality on the polymer's conformation. For dilute solutions, which at ambient temperature and pressure exhibit classic good-solvent behavior, a pressure-induced crossover from good to poor solvent behavior is found. Such measurements are shown to give a measure of ${\mathit{A}}_{2}$, an otherwise difficult to measure property at elevated pressure. Above the overlap concentration, this polymer system exhibits aggregate formation. The autocorrelation spectrum contains two relaxations: a fast relaxation mode associated with the usual cooperative diffusion and a slow relaxation mode associated with internal dynamics of the aggregates. Through DLS experiments in the semidilute regime we show that these two modes merge upon increasing pressure, an effect that is completely reversible. The dispersal of the aggregates under pressure suggests that the aggregates depend strongly on water-mediated hydrogen bonds between monomers. \textcopyright{} 1996 The American Physical Society.
A Quantitative Variant of the Multi-colored Motzkin---Rabin Theorem

We prove a quantitative version of the multi-colored Motzkin---Rabin theorem in the spirit of Barak et al. (Proceedings of the National Academy of Sciences, 2012): Let $$V_1,\ldots ,V_n \subset {\mathbb {R}}^d$$V1,?,Vn?Rd be $$n$$n disjoint sets of points (of $$n$$n `colors'). Suppose that for every $$V_i$$Vi and every point $$v \in V_i$$v?Vi there are at least $$\delta |V_i|$$?|Vi| other points $$u \in V_i$$u?Vi so that the line connecting $$v$$v and $$u$$u contains a third point of another color. Then the union of the points in all $$n$$n sets is contained in a subspace of dimension bounded by a function of $$n$$n and $$\delta $$? alone.
"Click" reactions: a versatile toolbox for the synthesis of peptide-conjugates

Peptides that comprise the functional subunits of proteins have been conjugated to versatile materials (biomolecules, polymers, surfaces and nanoparticles) in an effort to modulate cell responses, specific binding affinity and/or self-assembly behavior. However, the efficient and convenient synthesis of peptide-conjugates, especially the constructs with multiple types of peptide functionality remains challenging. In this critical review, we focus on “click” reactions that have been used to synthesis peptide-functionalized conjugates, introducing their reaction conditions, specifically elucidating parameters that influence reaction kinetics and total conversion, and highlighting examples that have been completed recently. Moreover, orthogonal “click” reactions that synthesize multi-functional biomaterials in a one-pot or sequential manner are noted. Through this review, a comprehensive understanding of “click” reactions aims to provide insight on how one might choose suitable “click” reactions to constitute peptide-functionalized molecules/surfaces/matrices for the development of advanced biomaterials.
Pituitary lactogenic hormone concentration during pregnancy in the rat.

A study was made in rats to ascertain whether the growth and secretory phases of themammary gland during pregnancy were associated with variation in concentration of pituitary lactogenic hormone. Pituitary lactogenic hormone levels were determined by the common pigeon micro method of assay. Pituitary weight was low during most of pregnancy, but increased markedly a short time before parturition (day 21). Pituitar lactogenic hormone increased during the first two-thirds of pregnancy during which time there was growth, but little secretory activity of the mammary gland. Peak concentration (.051 i.u. ⁄mg. pituitary) was reached on day 16. As the secretory activity of the mammary gland progressively increased during the last one-third of pregnancy, pituitary lactogenic hormone levels decreased markedly reaching the lowest point (.004 i.u.⁄mg.) on day 21. The significance of this is discussed. The influence of 1, 3.6, 15 and 50 µg.⁄day estradiol benzoate (E.B.) for 5 days upon pituitary weight and lactogenic h...
Auditor failure and market reactions: evidence from China

Zhongtianqin, the largest Chinese auditor in 2000, collapsed in 2001 owing to its audit failure. This study examines how the market reacted to the audit scandal in the Chinese institutional setting. Chinese investors are entitled to recover their investment losses from auditors owing to audit failure. However, civil lawsuits against auditors have not succeeded in the past. Therefore, Chinese auditors do not face the real threat of shareholder litigation. They only have the threat of costly governmental penalties for violating the regulations. Even so, we demonstrate that Chinese audit still contains both assurance and insurance values. Also, the entire market reacted to the scandal. Moreover, we show that investors differentiate audit quality in stock valuation. Finally, companies audited by international auditors suffered less value losses. This study adds to the worldwide literature on auditor failure.
Reaction of Phosphorus Chlorides with Ammonium Bicarbonate

Abstract Phosphorus pentachloride, phosphorus oxychloride and phosphorus trichloride reacted spontaneously with dry ammonium bicarbonate at room temperature. The major product from the pentachloride and oxychloride was tetraammonium pyrophosphate. The trichloride afforded a mixture of tetraammonium pyrophosphite and the pyrophosphate. In the presence of benzene, the product from the pentachloride appeared to be hydrolyzed by water formed during the reaction to diammonium phosphate. The appearance of tripolyphosphate in the nmr spectra of the products is discussed.
ON THE DETECTABILITY OF A PREDICTED MESOLENSING EVENT ASSOCIATED WITH THE HIGH PROPER MOTION STAR VB 10

Extrapolation of the astrometric motion of the nearby low-mass star VB 10 indicates that sometime in late 2011 December or during the first 2-3 months of 2012, the star will make a close approach to a background point source. Based on astrometric uncertainties, we estimate a 1 in 2 chance that the distance of closest approach {rho}{sub min} will be less than 100 mas, a 1 in 5 chance that {rho}{sub min} < 50 mas, and a 1 in 10 chance that {rho}{sub min} < 20 mas. The last would result in a microlensing event with a 6% magnification in the light from the background source and an astrometric shift of 3.3 mas. The lensing signal will however be significantly diluted by the light from VB 10, which is 1.5 mag brighter than the background source in B band, 5 mag brighter in I band, and 10 mag brighter in K band, making the event undetectable in all but the bluer optical bands. However, we show that if VB 10 happens to harbor a {approx}1 M{sub J} planet on a moderately wide ( Almost-Equal-To 0.18 AU-0.84 AU) orbit, there is a chance (1% to more than 10%, depending on themore » distance of closest approach and orbital period and inclination) that a passage of the planet closer to the background source will result in a secondary event of higher magnification. The detection of secondary events could be made possible with a several-times-per-night multi-site monitoring campaign.« less
Location of defective cells in HBT power amplifier arrays using IR emission microscopy

Abstract Single cell electric short failure mode of HBT power amplifier is presented with a discussion of its failure signature and mechanism. HBTs with low breakdown voltage of the base–collector junction are studied with an I–V curve tracer. Several controlled experiments were conducted in an effort to duplicate the failure signature and identify the root cause of the short failure. An infrared photoemission microscopy technique is demonstrated to be an efficient method to quickly locate a single weak HBT cell from the large parallel HBT transistor cell array that comprises the power amplifier output stage. Methods to estimate and reduce the failure rate are discussed.
Film-Cooling Effectiveness on a Gas Turbine Blade Tip Using Pressure-Sensitive Paint

Effects of the presence of squealer, the locations of the film-cooling holes, and the tip-gap clearance on the film-cooling effectiveness were studied and compared to those for a plane (flat) tip. The film-cooling effectiveness distributions were measured on the blade tip using the pressure-sensitive paint technique. Air and nitrogen gas were used as the film-cooling gases, and the oxygen concentration distribution for each case was measured. The film-cooling effectiveness information was obtained from the difference of the oxygen concentration between air and nitrogen gas cases by applying the mass transfer analogy. Plane tip and squealer tip blades were used while the film-cooling holes were located (a) along the camber line on the tip or (b) along the tip of the pressure side. The average blowing ratio of the cooling gas was 0.5, 1.0, and 2.0. Tests were conducted with a stationary, five-bladed linear cascade in a blow-down facility. The free-stream Reynolds number, based on the axial chord length and the exit velocity, was 1,138,000, and the inlet and the exit Mach numbers were 0.25 and 0.6, respectively. Turbulence intensity level at the cascade inlet was 9.7%.
Empirical Validation of Wireless Models in Simulations of Ad Hoc Routing Protocols

Computer simulation has been used extensively as an effective tool in the design and evaluation of systems. One should not, however, underestimate the importance of validation--the process of ensuring whether a simulation model is an appropriate representation of the real-world system. Validation of wireless network simulations is difficult due to strong interdependencies among protocols at different layers and uncertainty in the wireless environment. The authors present an approach of coupling direct-execution simulation and traces from real outdoor experiments to validating simple wireless models that are used commonly in simulations of wireless ad hoc networks. This article documents a common testbed that supports direct execution of a set of ad hoc routing protocol implementations in a wireless network simulator. By comparing routing behavior measured in the real experiment with behavior computed by the simulation, the authors validate the models of radio behavior upon which protocol behavior depends.
Rate of decay of s-numbers

For an operator T@?B(X,Y), we denote by a"m(T), c"m(T), d"m(T), and t"m(T) its approximation, Gelfand, Kolmogorov, and absolute numbers, respectively. We show that, for any infinite-dimensional Banach spaces X and Y, and any sequence @a"m@?0, there exists T@?B(X,Y) for which the inequality 3@a"@?"m"/"6"@?>=a"m(T)>=max{c"m(t),d"m(T)}>=min{c"m(t),d"m(T)}>=t"m(T)>=@a"m/9 holds for every m@?N. Similar results are obtained for other s-scales.
Recessions, Older Workers, and Longevity: How Long Are Recessions Good For Your Health?

Abstract Although past research has found that recessions reduce contemporaneous mortality, workers nearing retirement age may experience reduced longevity attributable to lengthy unemployment spells and lost health insurance at a particularly vulnerable time. To test this hypothesis, we generate age-specific cohort survival probabilities using 1965–2008 Vital Statistics mortality data and link them to labor market conditions at earlier ages. Our results indicate that experiencing a recession in one's late 50s reduces longevity. We also find that it leads to several years of reduced employment, health insurance coverage, and health care utilization, which may contribute to the lower long-term likelihood of survival. (JEL E32, I12, I13, J14, J26)
Induced subgraphs of hypercubes

Let Q"k denote the k-dimensional hypercube on 2^k vertices. A vertex in a subgraph of Q"k is full if its degree is k. We apply the Kruskal-Katona Theorem to compute the maximum number of full vertices an induced subgraph on n@?2^k vertices of Q"k can have, as a function of k and n. This is then used to determine min(max(|V(H"1)|,|V(H"2)|)) where (i) H"1 and H"2 are induced subgraphs of Q"k, and (ii) together they cover all the edges of Q"k, that is E(H"1)@?E(H"2)=E(Q"k).
A simple base-mediated amidation of aldehydes with azides

A practical and efficient amidation reaction involving aromatic aldehydes and various azides under mild conditions is described. A broad spectrum of functional groups was tolerated, and the amides were synthesized in moderate to excellent yields, presenting an attractive alternative to the currently available synthetic methods.
In the woods of M theory

We study BPS states which arise in compactifications of M-theory on Calabi-Yau manifolds. In particular, we are interested in the spectrum of the particles obtained by wrapping M2-brane on a two-cycle in the CY manifold X. We compute the Euler characteristics of the moduli space of genus zero curves which land in a holomorphic four-cycle S ⊂ X. We use M. Kontsevich's method which reduces the problem to summing over trees and observe the discrepancy with the predictions of local mirror symmetry. We then turn this discrepancy into a supporting evidence in favor of existence of extra moduli of M2-branes which consists of the choice of a flat U(1) connection recently suggested by C. Vafa and partially confirm this by counting of the arbitrary genus curves of bi-degree (2,n) in 1 × 1 (this part has been done together with Barak Kol). We also make a conjecture concerning the counting of higher genus curves using second quantized Penner model and discuss possible applications to the string theory of two-dimensional QCD.
A finite element–boundary element method for advection–diffusion problems with variable advective fields and infinite domains

Abstract In this paper a hybrid, finite element–boundary element method which can be used to solve for particle advection–diffusion in infinite domains with variable advective fields is presented. In previous work either boundary element, finite element, or difference methods were used to solve for particle motion in advective–diffusive domains. These methods have a number of limitations. Due to the complexity of computing spatially dependent Green's functions, the boundary element method is limited to domains containing only constant advective fields, and due to their inherent formulations, finite element and finite difference methods are limited to only domains of finite spatial extent. Thus, finite element and finite difference methods are limited to finite space problems for which the boundary element method is not, and the boundary element method is limited to constant advection field problems for which finite element and finite difference methods are not. In this paper it is proposed to split the total domain into two sub-domains, and for each of these sub-domains, apply the appropriate solution method; thereby, producing a method for the total infinite space, variable advective field domain.
Dental materials 1956–1958: A review

The author reviews 65 papers that ap­ peared in the literature from 1956 through 1958. The subjects covered in­ clude: biological effectsof dental mate­ rials; metallic materials, including amal­ gam, gallium-base alloys, gold-base alloys and chromium-cobalt alloys; ceramic materials, including porcelain, cements and investments; organic materials, in­ cluding denture base resins, relining resins, plastic teeth, direct filling resins and elastic impression materials; and the mechanical properties of enamel and dentin. Recent literature reveals a trend toward testing new dental materials bio­ logically before subjecting them to clin­ ical use.
Some Comments on Branes, G-Flux and K-Theory

Summary of a talk explaining three ways in which string theory and M-theory are related to the mathematics of K-theory.
Effect of solvent quality on the molecular dimensions of PAMAM dendrimers

The average dimensions of poly(amido amine) (PAMAM) dendrimers of generations G5 and G8 are studied by small-angle neutron scattering (SANS) as a function of solvents of differing quality, the composition of mixtures of a good solvent and a nonsolvent, and temperature. The radius of gyration, Rg, of the G8 dendrimer decreases for the series of solvents D(CD2)mOD (with m = 0, 1, 2, 4) by approximately 10% from m = 0 to m = 4 with decreasing solvent quality. The average segment density in solution is calculated for G5 and G8. The size of PAMAM dendrimers, as reflected by Rg, is not influenced by the composition of mixtures of methyl alcohol/acetone in the full range of solubility of the dendrimers. In the temperature range −10 °C ≤ T ≤ 50 °C, the dimensions of the G8 and G5 dendrimer are constant, within ≈5% of each other.
Holonomy on poisson manifolds and the modular class

The linear holonomy of a Poisson structure, introduced in the present paper, generalizes the linearized holonomy of a regular symplectic foliation. For singular Poisson structures the linear holonomy is defined for the lifts of tangential paths to the cotangent bundle. The linear holonomy is closely related to the modular class. Namely, the logarithm of the determinant of the linear holonomy is equal to the integral of the modular vector field along such a lift. This assertion relies on the notion of the integral of a vector field along a cotangent path on a Poisson manifold, which is also introduced in the paper.
Stochastic completion fields: a neural model of illusory contour shape and salience

We describe an algorithm- and representation-level theory of illusory contour shape and salience. Unlike previous theories, our model is derived from a single assumption: that the prior probability distribution of boundary completion shape can be modeled by a random walk in a lattice whose points are positions and orientations in the image plane (i.e., the space that one can reasonably assume is represented by neurons of the mammalian visual cortex). Our model does not employ numerical relaxation or other explicit minimization, but instead relies on the fact that the probability that a particle following a random walk will pass through a given position and orientation on a path joining two boundary fragments can be computed directly as the product of two vector-field convolutions. We show that for the random walk we define, the maximum likelihood paths are curves of least energy, that is, on average, random walks follow paths commonly assumed to model the shape of illusory contours. A computer model is demonstrated on numerous illusory contour stimuli from the literature.
Transforming high-level data-parallel programs into vector operations

Efficient parallel execution of a high-level data-parallel language based on nested sequences, higher order functions and generalized iterators can be realized in the vector model using a suitable representation of nested sequences and a small set of transformational rules to distribute iterators through the constructs of the language.
Nearest-neighbor correlation effects in spinless one-dimensional conductors

Certain anisotropic conductors such as tetracyanoquinodimethane (TCNQ) salts can be modeled as one-dimensional systems with spinless electrons. This theoretical study covered nearest-neighbor correlation effects on the ground state and the soliton excitations of these models. The results described are the first solutions of the many-body Hamiltonian for all values of the correlation strength, obtained by finding eigenvectors of very large matrices. For finite systems, the ground state has a conditional Peierls transition for all values of the correlation energy $V$. The trends with increasing size indicate a critical transition. The infinite systems will dimerize for Hubbard $V l2t$ and the degree of dimerization increases with $V$. The dimerization abruptly terminates at $V=2t$. Similar results on the $\mathrm{XXZ}$ spin model are confirmed by behavior predicted using scaling relationships. The trends in soliton energy, width, and charge distribution have been calculated. Solitons are the lowest-energy charge carriers in systems which dimerize. The solitons in the spinless conductor carry fractional charge and those in the $\mathrm{XXZ}$ spin model have fractional spin. The charge on the most depleted site provides a useful measure of $V$. The solitons do not have a significant activation energy and should be highly mobile.
Incentive-Compatible Interdomain Routing with Linear Utilities

We revisit the problem of incentive-compatible interdomain routing, examining the quite realistic special case in which the utilities of autonomous systems (ASes) are linear functions of the traffic in the incident links and the traffic leaving each AS. We show that incentive-compatibility toward maximizing total welfare is achievable efficiently, and in the uncapacitated case, by an algorithm that can be easily implemented by the border gateway protocol (BGP), the standard protocol for interdomain routing.
Serendipitous Detections of XTE J1906+09 with the Rossi X-ray Timing Explorer

The 89 s X-ray pulsar XTE J1906+09 was discovered during Rossi X-Ray Timing Explorer (RXTE) observations of SGR 1900+14 in 1996. Because of monitoring campaigns of SGR 1900+14, XTE J1906+09 was also monitored regularly in 1996 September, 1998 May-June, 1998 August-1999 July, and 2000 March-2001 January. A search for pulsations resulted in detections of only the two previously reported outbursts in 1996 September and 1998 August-September. Pulsed flux upper limits for the rest of the observations show that XTE J1906+09 is a transient X-ray pulsar and likely has a Be star companion. The RXTE all-sky monitor did not reveal XTE J1906+09. Pulse-timing analysis of the second outburst discovered a sinusoidal signature in the pulse frequencies that is likely produced by an orbital periastron passage. Fits to pulse phases using an orbital model and quadratic phase model have chi(exp 2) minima at orbital periods of 26-30 days for fixed mass functions of 5, 10, 15, and 20 solar masses. The pulse shape showed energy- and intensity-dependent variations. Pulse-phase spectroscopy quantified the energy-dependent variations. The phase-averaged spectrum used the pulse minimum spectrum as the background spectrum to eliminate effects from SGR 1900+14 and the Galactic ridge and was well fitted by an absorbed power law with a high-energy cutoff with column density N(sub H) = 6 +/- 1 x 10(exp 22)/sq cm, a photon index of 1.01 +/- 0.08, cutoff energy E(sub cut) = 11 +/- 1 keV, and e-folding energy E(sub fold) = 19 +/- 4 keV. Estimated 2-10 keV peak fluxes, corrected for contributions from the Galactic ridge and SGR 1900+14, are 6 x l0(exp -12) and 1.1 x 10(exp -10) ergs/sq cm/s for the 1996 and 1998 outbursts, respectively. XTE J1906+09 may be part of an unusual class of Be/X-ray binaries that do not lie on the general spin period versus orbital period correlation with the majority of Be/X-ray binaries.
Preparation of aminosaccharides using ester-imine condensations: syntheses of methyl N-benzoylacosaminide and methyl N-[oxo(phenylmethoxy)acetyl]daunosaminide from (S)-ethyl 3-hydroxybutyrate

Abstract The dianion of (S)-ethyl β-hydroxybutyrate (1) was treated with N -trimethylsilyl Imine 2 to afford β-lactam 4. The same dianion reacted with N -ary1 imine 10 to give β-lactams 11, 12, and 13. A three-step sequence was used to convert 4 into the β-lactam-pyran hybrid 9 while a five-step sequence was developed to transform 11 and 12 into 9. Application of the carboxyinversion reaction to derivatives of 9 afforded protected analogs of the amino-saccharldes daunosamlne (5) and acosamine (6).
When is it important to know you've been rejected? A search problem with probabilistic appearance of offers

Abstract A problem that often arises in the process of searching for a job or for a candidate to fill a position is that applicants do not know if they will receive an offer from any given firm with which they interview, and, conversely, firms do not know whether applicants will definitely take positions they are offered. In this paper, we model the search process as an optimal stopping problem with probabilistic appearance of offers from the perspective of a single decision-maker who wants to maximize the realized value of the offer she accepts. Our main results quantify the value of information in the following sense: how much better off is the decision-maker if she knows each time whether an offer appeared or not, compared to the case where she is only informed when offers actually appear? We show that for some common distributions of offer values, she can expect to receive very close to her optimal value even in the lower information case, as long as she knows the probability that any given offer will appear. However, her expected value in the low information case (as compared to the high information case) can fall dramatically when she does not know the appearance probability ex ante but must infer it from data. This suggests that hiring and job-search mechanisms may not suffer from serious losses in efficiency or stability from participants hiding information about their decisions, unless agents are uncertain of their own attractiveness as employees or employers.
Maximum entropy lighting for physical objects

This paper presents a principled method for choosing informative lighting directions for physical objects. An ensemble of images of an object or scene is captured, each with a known, predetermined lighting direction. Diffuse reflection functions are then estimated for each pixel across such an ensemble. Once these are estimated, the object or scene can be interactively relit as it would appear illuminated from an arbitrary lighting direction. We present two approaches for evaluating images as a function of lighting direction. The first uses image compressibility evaluated across a grid of samples in lighting space. The second uses image variance and prediction error variance, which are monotonically related to compressibility for Gaussian distributions. The advantage of the variance approach is that both image variance and prediction error variance can be analytically derived from the scene reflection functions, and evaluated at the rate of a few nanoseconds per lighting direction.
Backup Nutation Damping Strategy for the Galileo Spacecraft

This paper discusses the design of remedial measures that can be taken to achieve reasonable nutation damping of the Galileo spacecraft in the event of failure of its boom damper in flight. One scheme exploits the effects of payload motion on the nutational stability of a spinning spacecraft. This scheme demands that the spacecraft motion compensation algorithm be enabled with the scan platform bore sight pointed in a well chosen direction to produce rapid damping of spacecraft nutation. A second method suggested for nutation damping is a thruster-based open loop control algorithm, utilizing a pair of thrusters as actuators.
USING HIGH-RESOLUTION OPTICAL SPECTRA TO MEASURE INTRINSIC PROPERTIES OF LOW-MASS STARS: NEW PROPERTIES FOR KOI-314 AND GJ 3470

We construct high signal-to-noise "template" spectra by co-adding hundreds of spectra of nearby dwarfs spanning K7 to M4, taken with Keck/HIRES as part of the California Planet Search. We identify several spectral regions in the visible (370-800 nm) that are sensitive to the stellar luminosity and metallicity. We use these regions to develop a spectral calibration method to measure the mass, metallicity, and distance of low-mass stars, without the requirement of geometric parallaxes. Testing our method on a sample of nearby M dwarfs, we show that we can reproduce stellar masses to about 8%-10%, metallicity to ~0.15 dex, and distance to 11%. We were able to make use of HIRES spectra obtained as part of the radial velocity monitoring of the star KOI-314 to derive a new mass estimate of 0.57 ± 0.05 M_☉, a radius of 0.54 ± 0.05 R_☉, a metallicity, [Fe/H], of –0.28 ± 0.10, and a distance of 66.5 ± 7.3 pc. Using HARPS archival data and combining our spectral method with constraints from transit observations, we are also able to derive the stellar properties of GJ 3470, a transiting planet hosting M dwarf. We estimate a mass of 0.53 ± 0.05 M_☉, a radius of 0.50 ± 0.05 R_☉, a metallicity, [Fe/H], of 0.12 ± 0.12, and a distance of 29.9±_(3.4)^(3.7)pc.
Semiprojectivity for certain purely infinite $C^*$-algebras

It is proved that classifiable simple separable nuclear purely infinite C*-algebras having finitely generated K-theory and torsion-free K 1 are semiprojective. This is accomplished by exhibiting these algebras as C*-algebras of infinite directed graphs.
Retrospective on studies of ligand substitution reactions of metal complexes

Presentation de travaux concernant la reactivite et le mecanisme de substitutions de coordinats dans des complexes metalliques. Synthese bibliographique
Rough-wall turbulent heat transfer with step-wall temperature boundary conditions

Stanton number measurements are presented for the turbulent boundary layer flow of air on rough-wall flat plates with both constant wall temperature and step wall temperature boundary conditions. Two rough surfaces were used—one roughened with hemispheres spaced four diameters apart and the other with hemispheres spaced two diameters apart. The data are compared with each other and with results from a smooth surface tested in the same experimental facility. It is found that, when plotted as the ratio of Stanton number to constant wall temperature Stanton number vs the ratio of unheated length to distance from the leading edge, the data from the smooth and rough surfaces scatter about a single curve. This gives a new kernel function that, when used in the superposition solution of the arbitrary wall temperature problem, yields good results for both smooth and rough surfaces.
Hydrogen embrittlement and grain boundary fracture

This paper describes the relationship between intergranular and transgranular fracture modes of hydrogen embrittlement. The interaction of a transgranular crack, propagating under constant stress in a gaseous hydrogen environment of 40kPa with a grain boundary, is shown. Transgranular fracture is observed when the hydrogen distribution is enhanced at the tip of a notch because either that is the point at which hydrogen enters from the gas phase or concentrates from the solid solution due to the stress field. Intergranular fracture is alternately observed when there is a hydrogen concentration at the grain boundary higher than at other places in the solid. Higher hydrogen concentrations have been observed at grain boundaries in Ni-H alloys using a Secondary Ion Mass Spectrometer technique. The presence of segregated S at the grain boundaries was also shown to enhance the concentration of hydrogen there.
Thermal response of substrate structural materials during a plasma disruption

Intense energy fluxes to in-vessel components like the first wall and the divertor plate of a fusion reactor are expected during plasma disruptions. This high energy deposition in short times may cause severe surface erosion of these components resulting from melting and vaporization. Coatings and tile materials are proposed to protect and maintain the integrity of the underneath structural materials from both erosion losses as well as from high thermal stresses encountered during a disruption. The coating thickness should be large enough to withstand both erosion losses and to reduce the temperature rise in the substrate structural material. Yet the coating thickness should be minimized to reduce potential problems from radioactivity, toxicity, and plasma contamination. Tile materials such as graphite and coating materials such as tungsten and beryllium on structural materials like copper and steel are analyzed as potential divertor and first wall design options. The minimum coating thickness required to protect the structural material is discussed for a range of disruption parameters.