cssi/SciSciGPT-SciSciNet huggingface dataset:
RESONANCE SCATTERING PHASE SHIFTS ON A NON-REST FRAME LATTICE

Abstract Many low energy hadrons, such as the rho, can be observed as resonances in scattering experiments. A proposal by Luscher enables one to determine infinite volume elastic scattering phases from the two-particle energy spectrum measured from finite periodic lattices. In this work, we generalize the formalism to the case where the total momentum of the particles is non-zero; i.e. the lattice frame is not the center-of-mass frame of the scattering particles. There are several advantages to this procedure including making a wider variety of center of mass energies accessible with a fixed lattice volume, and making the avoided level crossing in a P-wave decay occur with a smaller volume. The formalism is tested with a simple lattice model of two fields with different masses and a 3-point coupling in 3 + 1 dimensions. We find remarkable agreement between the rest-frame and non-rest-frame scattering.
Crystal growth of uranium-containing complex oxides: Ba2Na0.83U1.17O6, BaK4U3O12 and Na3Ca1.5UO6

Abstract Single crystals of complex uranium oxides, Ba2Na0.83U1.17O6, BaK4U3O12 and Na3Ca1.5UO6, were grown out of reactive carbonate melts. The crystal structures the three uranates were determined by single crystal X-ray diffraction. Ba2Na0.83U1.17O6 crystallizes in the F m 3 ¯ m space group, a = 8.6173(1), with a disordered cubic double perovskite structure. BaK4U3O12 forms in the cubic I m 3 ¯ m space group, a = 8.7232(1), with the asymmetric unit consisting of three metal positions, which shows improvement of the structure refinement from the published results. Na3Ca1.5UO6 crystallizes in the orthorhombic Fddd space group with a = 6.6573(2), b = 9.6111(3) and c = 20.1155(5) in a rock salt superstructure. In all three oxides the U(VI) cation is octahedrally coordinated. While the UO6 octahedra in Ba2Na0.83U1.17O6 are undistorted due to oxygen disorder, the UO6 octahedra in BaK4U3O12 and Na3Ca1.5UO6 feature the typical uranyl geometry with four long two short U–O bonds.
Selective urokinase-type plasminogen activator (uPA) inhibitors. Part 1: 2-Pyridinylguanidines.

The identification of 2-pyridinylguanidines (e.g., 27 and 28) as selective inhibitors of urokinase-type plasminogen activator (uPA) is described. The X-ray crystal structure of 27 has been determined, and modelling has been used to predict binding in the enzyme active site.
Perturbations from cosmic strings in cold dark matter

A systematic linear analysis of the perturbations induced by cosmic strings in cold dark matter is presented. The power spectrum is calculated and it is found that the strings produce a great deal of power on small scales. It is shown that the perturbations on interesting scales are the result of many uncorrelated string motions, which indicates a much more Gaussian distribution than was previously supposed.
The Effect of File Sharing on Record Sales: An Empirical Analysis

For industries ranging from software to pharmaceuticals and entertainment, there is an intense debate about the appropriate level of protection for intellectual property. The Internet provides a natural crucible to assess the implications of reduced protection because it drastically lowers the cost of copying information. In this paper, we analyze whether file sharing has reduced the legal sales of music. While this question is receiving considerable attention in academia, industry, and Congress, we are the first to study the phenomenon employing data on actual downloads of music files. We match an extensive sample of downloads to U.S. sales data for a large number of albums. To establish causality, we instrument for downloads using data on international school holidays. Downloads have an effect on sales that is statistically indistinguishable from zero. Our estimates are inconsistent with claims that file sharing is the primary reason for the decline in music sales during our study period.
The use of isotope effects to determine enzyme mechanisms

Isotope effects are one of the most powerful kinetic tools for determining enzyme mechanisms. There are three methods of measurement. First, one can compare reciprocal plots with labeled and unlabeled substrates. The ratio of the slopes is the isotope effect on V/K, and the ratio of the vertical intercepts is the isotope effect on V(max). This is the only way to determine V(max) isotope effects, but is limited to isotope effects of 5% or greater. The second method is internal competition, where the labeled and unlabeled substrates are present at the same time and the change in their ratio in residual substrate or in product is used to calculate an isotope effect, which is that on V/K of the labeled reactant. This is the method used for tritium or (14)C, or with the natural abundances of (13)C, (15)N, or (18)O. The third method involves perturbations from equilibrium when a labeled substrate and corresponding unlabeled product are present at chemical equilibrium. This also gives just an isotope effect on V/K for the labeled reactant. The chemistry is typically not fully rate limiting, so that the isotope effect on V/K is given by: (x)(V/K)=((x)k+c(f)+c(r)(x)K(eq))/(1+c(f)+c(r)) where x defines the isotope (D, T, 13, 15, 18 for deuterium, tritium, (13)C, (15)N, or (18)O), and (x)(V/K), (x)k, and (x)K(eq) are the observed isotope effect, the intrinsic one on the chemical step, and the isotope effect on the equilibrium constant, respectively. The constants c(f) and c(r) are commitments in forward and reverse directions, and are the ratio of the rate constant for the chemical reaction and the net rate constant for release from the enzyme of the varied substrate (direct comparison) or labeled substrate (internal competition and equilibrium perturbation) for c(f), or the first product released or the one involved in the perturbation for c(r). The intrinsic isotope effect, (x)k, can be estimated by comparing deuterium and tritium isotope effects on V/K, or by comparing the deuterium isotope effect with (13)C ones with deuterated and undeuterated substrates. Adding a secondary deuterium isotope effect and its effect on the (13)C one can give an exact solution for all intrinsic isotope effects and commitments. The effect of deuteration on a (13)C isotope effect allows one to tell if the two isotope effects are on the same or different steps. Applications of these methods to several enzyme systems will be presented.
Optimal scheduling for fair resource allocation in ad hoc networks with elastic and inelastic traffic

This paper studies the problem of congestion control and scheduling in ad hoc wireless networks that have to support a mixture of best-effort and real-time traffic. Optimization and stochastic network theory have been successful in designing architectures for fair resource allocation to meet long-term throughput demands. However, to the best of our knowledge, strict packet delay deadlines were not considered in this framework previously. In this paper, we propose a model for incorporating the quality-of-service (QoS) requirements of packets with deadlines in the optimization framework. The solution to the problem results in a joint congestion control and scheduling algorithm that fairly allocates resources to meet the fairness objectives of both elastic and inelastic flows and per-packet delay requirements of inelastic flows.
Born-Infeld actions from Matrix theory

Abstract We propose a formula for the effective action of Matrix theory which successfully reproduces a large class of Born-Infeld type D-brane probe actions. The formula is motivated by demanding consistency with known results, and is tested by comparing with a wide range of source-probe calculations in supergravity. In the case of D0-brane sources and D p -bra probes, we study the effect of boosts, rotations, and world-volume electric fields on the probe, and find agreement with supergravity to all orders in the gravitational coupling. We also consider D4-brane sources at the one-loop level and recover the correct probe actions for a D0-brane, and for a D4-brane rotated at an angle with respect to the source.
Ordinary reduction of K3 surfaces

Let X be a K3 surface over a number field K. We prove that there exists a finite algebraic field extension E/K such that X has ordinary reduction at every non-archimedean place of E outside a density zero set of places.
Analyzing the Politics of Health Care: Let's Buy Ourselves Some Civilization

The United States has a population of three hundred million, according to latest Census Bureau estimates. Forty-seven million, including many non-citizens, are uninsured. That is, 16% of the total United States population has no health insurance. Millions more have inadequate coverage and are in danger of losing that. Private, corporatized medical coverage, structured by the insurance industry, is the basis for the current system. This article is an attempt to lay out the principal health care issues, to look at the alternatives and the cost of those alternatives, and to try to determine whether there is a particular regime that, despite its imperfections, is the best available to us now.
The Generalized Wolf Shift for Cyclostationary Fields

Correlation-dependent, propagation-induced shifts in the generalized spectra of cyclostationary, random fields are predicted. This result generalizes the Wolf shift for stationary fields and is applicable to periodic trains of fast pulses.
Intense microvascular constriction after angioplasty of acute thrombotic coronary arterial lesions.

Abstract Immediately after balloon dilation of a fresh thrombotic coronary lesion, 5 patients had angina, ST segment elevation, and a striking reduction of blood flow in the dilated artery. A mean (SEM) pressure gradient across the dilated lesion of only 3(1) mm Hg and an average minimum lesion diameter of 1·7 mm indicated that the decline in resting blood flow was not due to obstruction at the site of the original lesion. Neither distal vascular emboli nor side branch occlusions were visible on the angiogram. An increase in distal coronary artery pressure during a subsequent balloon inflation suggested that the site of vasoconstriction was distal to the origin of collateral vessels. The syndrome lasted 48-80 min and was not reversed with nitroglycerin or thrombolytic drugs. Papaverine lessened the syndrome transiently on one occasion. Such microvascular constriction, caused by release of potent vasoconstrictors from the clot, may partly explain the failure of emergency angioplasty to reduce infarct size in acute myocardial infarction.
Classification Analysis of Traffic Improvement Sites

Results of an application of the case study approach to the evaluation of alternative TSM strategies is presented. The procedure is useful in the classification of potential sites relative to their expected performance following implementation of specific TSM strategies designed to improve flow conditions. The specific focus of the paper is on the use of classification analysis as a means of tranferring analysis results drawing from a small number of representative case studies to a broader range of alternative applications. This approach is shown to provide a reasonable and less costly alternative to individual site-by-site analyses.
An Examination of Corporate Tax Shelter Participants

ABSTRACT: Recent evidence suggests that corporate tax shelters have become important corporate instruments for reducing tax burden. Based on a sample of identified tax shelter participants, I develop a profile of the type of firm that likely engages in tax sheltering. The model detects tax shelter participants through the use of variables predicted to be either affected by or associated with tax sheltering. I find that firms actively engaged in tax sheltering exhibit larger ex post book‐tax differences and more aggressive financial reporting practices. Using this model of tax shelter firm characteristics, I identify a broad sample of predicted tax shelter firms from the population of firms. I then examine whether tax sheltering is associated with wealth creation for shareholders or with managerial opportunism. I find that active tax shelter firms with strong corporate governance exhibit positive abnormal returns. This finding is consistent with tax sheltering being a tool for wealth creation in well‐gover...
Measurement of the temperature of cold highly charged ions produced in an electron beam ion trap

Abstract The temperature of highly charged titanium ions produced and trapped in an electron beam ion trap was determined by precisely measuring the broadening of K-shell emission lines in Ti19+ caused by the thermal Doppler motion. While interacting with a 3330 V electron beam the measured temperature of the titanium ions ranges from about 700 eV when the ions are confined in a deep trap to about 70 eV for ions in a shallow trap. The latter value represents the lowest temperature at which the K-shell X-ray emission from highly charged titanium ions has ever been recorded.
Distributed algorithms for maximum lifetime routing in wireless sensor networks

A sensor network of nodes with wireless transceiver capabilities and limited energy is considered. We propose distributed algorithms to compute an optimal routing scheme that maximizes the time at which the first node in the network drains out of energy. The problem is formulated as a linear programming problem and subgradient algorithms are used to solve it in a distributed manner. The resulting algorithms have low computational complexity and are guaranteed to converge to an optimal routing scheme that maximizes the network lifetime. The algorithms are illustrated by an example in which an optimal flow is computed for a network of randomly distributed nodes. We also show how our approach can be used to obtain distributed algorithms for many different extensions to the problem. Finally, we extend our problem formulation to more general definitions of network lifetime to model realistic scenarios in sensor networks
An improved, efficient route to 2,2-difluoroethenylbenzenes

Abstract Treatment of vinylidene fluoride with tert-BuLi at −115 °C gave a solution of [F2C CHLi]. Addition of Bu3SnCl to this lithium reagent at −110 °C gave an 88% isolated yield of F2C CHSnBu3. Reaction of F2C CHSnBu3 with substituted aryl iodides under Stille-Liebeskind conditions [Pd(PPh3)4/Cu(I)I] at room temperature afforded the 2,2-difluoroethenylbenzines in good yield. In the absence of the Cu(I)I co-catalyst, no reaction occurred. This work provides the most efficient route for the conversion of aryl halides to 2,2-difluorostyrenes.
Naiveté and Cynicism in Negotiations and Other Competitive Contexts

A wealth of literature documents how the common failure to think about the self-interests of others contributes to suboptimal outcomes. Yet sometimes, an excess of cynicism appears to lead us to over-think the actions of others and make negative attributions about their motivations without sufficient cause. In the process, we may miss opportunities that greater trust might capture. We review the research on when people expect too little or too much self-interest in the intentions of others, as contrasted with rational behavior. We also discuss the antecedents and consequences of these naive and cynical errors, as well as some potential strategies to buffer against their effects and achieve better outcomes in competitive contexts.
Employer Demand for Welfare Recipients by Race

This article examines employer demand for welfare recipients using new employer survey data. The results suggest that demand is high but sensitive to business cycle conditions. Factors including skill needs and industry affect prospective employer demand for recipients, while other characteristics that affect their relative supply to employers (e.g., establishment location) influence whether such demand is realized in actual hiring. The conditional demand for black and Hispanic welfare recipients lags behind their representation in the welfare population and seems affected by employers’ location and indicators of preferences. Thus, many demand‐side factors limit the employment options of welfare recipients, especially minorities.
Approximate Phase Change Solutions for Insulated Buried Cylinders

The conduction problem for cylinders embedded in a medium with variable thermal properties cannot be solved exactly if phase change occurs. New, approximate solutions have been found using the quasi-steady method. These solutions consider heat flow from the entire pipe surface rather than from a single point, as has been assumed in the past. The temperature field, phase change location, and pipe surface heat transfer can be evaluated using graphs presented for parametric ranges of temperature, thermal properties, burial depth, and insulation thickness. 14 refs.
Homicides, exchange rates, and northern border retail activity in Mexico

Exchange rate fluctuations and international business cycles may acutely affect retail sales in border regions where residents have the option of shopping in the neighboring country. This study examines the determinants of retail sales in six cities located along Mexico’s northern border. Retail activity in these cities is found to increase in tandem with real depreciations of the peso, lower unemployment rates in neighboring US counties, and increased border crossings. Taken together, these results suggest that cross-border shopping contributes to retail activity in the northern border region of Mexico. The opportunities for cross-border shopping may also condition the impact of violent crime on border region retail sales. In recent years, northern Mexico has been deeply affected by a crime wave associated with competition among drug cartels. Homicides related to organized crime are found to have a statistically significant negative impact on retail sales. A surge in crime levels may stifle retail activity in affected areas as extortion and attacks force some stores to close or reduce operating schedules at the same time that some potential customers elect to shop in relatively safer districts across the international divide.
Genetics of gene expression characterizes response to selective breeding for alcohol preference.

Numerous selective breeding experiments have been performed with rodents, in an attempt to understand the genetic basis for innate differences in preference for alcohol consumption. QTL analysis has been used to determine regions of the genome that are associated with the behavioral difference in alcohol preference/consumption. Recent work suggests that differences in gene expression represent a major genetic basis for complex traits. Therefore, the QTLs are likely to harbor regulatory regions (eQTLs) for the differentially expressed genes that are associated with the trait. In the present study, we examined brain gene expression differences over generations of selection of the third replicate lines of High and Low Alcohol Preferring (HAP3 and LAP3) mice, and determined regions of the genome that control the expression of these differentially expressed genes (deeQTLs). We also determined eQTL regions (rveQTLs) for genes that showed a decrease in variance of expression levels over the course of selection. We postulated that deeQTLs that overlap with rveQTLs, and also with phenotypic QTLs, represent genomic regions that are affected by the process of selection. These overlapping regions controlled the expression of candidate genes (that displayed differential expression and reduced variance of expression) for the predisposition to differences in alcohol consumption by the HAP3/LAP3 mice.
Is the stock market efficient

A stock market is said to be efficient if it accurately reflects all relevant information in determining security prices. Critics have asserted that share prices are far too volatile to be explained by changes in objective economic events—the October 1987 crash being a case in point. Although the evidence is not unambiguous, reports of the death of the efficient market hypothesis appear premature.
Sideways tunnelling and fractional Josephson frequency in double-layered quantum Hall systems

The filling fraction 1/k double-layered quantum Hall state has been shown to exhibit many superfluid properties. Here we propose the notion of sideways tunnelling, in which a current tunnels between two such 1/k states through an incompressible fractional quantum Hall state of filling fraction 2/m. We predict an alternating tunnelling current or a narrow-band noise at a frequency ω = eV/m, as a consequence of the tunnelling of e/m fractional charges.
The decategorification of bordered Khovanov homology

In [A type D structure in Khovanov homology, preprint (2013), arXiv:1304.0463; A type A structure in Khovanov homology, preprint (2013), arXiv:1304.0465] the author constructed a package which describes how to decompose the Khovanov homology of a link ℒ into the algebraic pairing of a type D structure and a type A structure (as defined in bordered Floer homology), whenever a diagram for ℒ is decomposed into the union of two tangles. Since Khovanov homology is the categorification of a version of the Jones polynomial, it is natural to ask what the types A and D structures categorify, and how their pairing is encoded in the decategorifications. In this paper, the author constructs the decategorifications of these two structures, in a manner similar to I. Petkova's decategorification of bordered Floer homology, [The decategorification of bordered Heegaard-Floer homology, preprint (2012), arXiv:1212.4529v1], and shows how they recover the Jones polynomial. We also use the decategorifications to compare this approach to tangle decompositions with M. Khovanov's from [A functor-valued invariant of tangles, Algebr. Geom. Topol.2 (2002) 665–741].
General and efficient catalytic amination of aryl chlorides using a palladium/bulky nucleophilic carbene system

A combination of palladium and an imidazolium chloride has been used as catalyst precursor in the amination of aryl chlorides. The imidazolium salt IPrHCl (4, IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) was found to provide the most efficient transformation rates in this catalytic system. This new system proves general and efficient for aryl chlorides as well as aryl bromides and iodides.
Thermal performance modeling of NASA’s scientific balloons

Abstract Initial studies of the thermal profiles on scientific balloons along with preliminary results are discussed in this paper. This document also emphasizes the impact thermal modeling will have on the design and future development of the scientific balloons. Progress of study and future steps to keep up with the design criteria is also included in this document.
Attention Patterns in the Boardroom: How Board Composition and Processes Affect Discussion of Entrepreneurial Issues

Using upper echelons theory and the concept of “faultlines,” we argue that heterogeneity on a board of directors influences discussion of entrepreneurial issues in board meetings. We also propose t...
Studies in the approximate control of flexible structures

Abstract Approximate control techniques are introduced for vibration suppression of linear time-varying and nonlinear structural systems. The large number of degrees of freedom required to model structures makes it difficult to apply to them techniques developed for low-order nonlinear or time-varying systems. We consider in this paper three approaches that provide linear approximations for the time-varying or nonlinear terms in the equations of motion. The control design is based on the linearized model. It is shown that each approximation has its advantages and shortcomings and that the type of approximation to use should be based on the objectives of the control, as well as the characteristics of the nonlinearity and the time variance of the system.
An Empirical Benchmark for Decadal Forecasts of Global Surface Temperature Anomalies

AbstractThe suitability of a linear inverse model (LIM) as a benchmark for decadal surface temperature forecast skill is demonstrated. Constructed from the observed simultaneous and 1-yr lag covariability statistics of annually averaged sea surface temperature (SST) and surface (2 m) land temperature global anomalies during 1901–2009, the LIM has hindcast skill for leads of 2–5 yr and 6–9 yr comparable to and sometimes even better than skill of the phase 5 of the Coupled Model Intercomparison Project (CMIP5) model hindcasts initialized annually over the period 1960–2000 and has skill far better than damped persistence (e.g., a local univariate AR1 process). Over the entire post-1901 record, the LIM skill pattern is similar but has reduced amplitude. Pronounced similarity in geographical variations of skill between LIM and CMIP5 hindcasts suggests similarity in their sources of skill as well, supporting additional evaluation of LIM predictability. For forecast leads above 1–2 yr, LIM skill almost entirely ...
Asymptotics for the Fredholm determinant of the sine kernel on a union of intervals

In the bulk scaling limit of the Gaussian Unitary Ensemble of hermitian matrices the probability that an interval of lengths contains no eigenvalues is the Fredholm determinant of the sine kernel $$\frac{{\sin (x - y)}}{{\pi (x - y)}}$$ over this interval. A formal asymptotic expansion for the determinant ass tends to infinity was obtained by Dyson. In this paper we replace a single interval of lengths bysJ, whereJ is a union ofm intervals and present a proof of the asymptotics up to second order. The logarithmic derivative with respect tos of the determinant equals a constant (expressible in terms of hyperelliptic integrals) timess, plus a bounded oscillatory function ofs (zero ifm=1, periodic ifm=2, and in general expressible in terms of the solution of a Jacobi inversion problem), pluso(1). Also determined are the asymptotics of the trace of the resolvent operator, which is the ratio in the same model of the probability that the set contains exactly one eigenvalue to the probability that it contains none. The proofs use ideas from orthogonal polynomial theory.
A CONVENIENT AND EFFECTIVE SYNTHESIS OF 3-(3,5-DIMETHOXYPHENYL)PROPANAL

A convenient and effective synthesis of 3-(3,5-dimethoxyphenyl) propanal, an important intermediate in the synthesis of various biologically active compounds is described.
Excitation of the Sr and Sr+ resonance lines by electron impact on Sr atoms

The relative optical excitation functions and polarizations of the Sr resonance line (4607 \AA{}) and of the ${\mathrm{Sr}}^{+}$ resonance lines (4078 and 4216 \AA{}) have been measured, using crossed electron and strontium-atom beams, for electron energies from the excitation thresholds to 1497 eV. The electron-beam energy resolution was \ensuremath{\sim} 0.22 eV for energies below 13 eV, and the atom beam was optically thin. The excitation functions of the ionic lines were measured relative to that of the atomic resonance line at fixed energies near the maxima of the excitation functions. Using spontaneous-emission branching ratios, this yields the ratios of total excitation cross sections for the atomic and ionic resonance levels (including cascades). The Sr $5^{1}P$ excitation function has been normalized to Born theory taking account of cascade at 1497 eV, where the energy dependence of the excitation function has converged to the theoretical behavior. The resulting normalized cross sections have been compared with available theoretical calculations and other measurements. The 4607-\AA{} polarization function is consistent with the theoretical threshold limit within experimental uncertainity.
A Mechanism for the Production of Jets and Ansae in Planetary Nebulae

The general properties of elliptical planetary nebulae have been very successfully explained by a class of hydrodynamic models known as interacting stellar winds (ISW). PNs also contain a variety of microstructures (Anase, ”FLIERs”) whose origins have remained puzzling. We (Frank, Balick, & Livio 1996) have shown that such flows will naturally occur in the ISW model in momentum-conserving PPN bubbles, and that they can naturally account for the formation of jets and ansae in a way consistent with extant observations.
Destination-sequenced distance vector (DSDV) routing protocol implementation in ns-3

Routing protocols are a critical aspect to performance in mobile wireless networks. The development of new protocols requires testing against well-known protocols in various simulation environments. In this paper we present an overview of several well-known MANET routing protocols and the implementation details of the DSDV routing protocol in the ns-3 network simulator. We analyse DSDV routing performance under various scenarios and compare its performance with the other protocols implemented in ns-3, AODV and OLSR. Our results verify the implementation of DSDV and show performance comparable to that of OLSR.
Holographic Spontaneous Parity Breaking and Emergent Hall Viscosity and Angular Momentum

We study the spontaneous parity breaking and generating of Hall viscosity and angular momentum in holographic p + ip model, which can describe strongly-coupled chiral superfluid states in many quantum systems. The dual gravity theory, an SU(2) gauge field minimally coupled to Einstein gravity, is parity-invariant but allows a black hole solution with vector hair corresponding to a parity-broken superfluid state. We show that this state possesses a non-vanishing parity-odd transport coefficient — Hall viscosity — and an angular momentum density. We first develop an analytic method to solve this model near the critical regime and to take back-reactions into account. Then we solve the equation for the tensor mode fluctuations and obtain the expression for Hall viscosity via Kubo formula. We also show that a non-vanishing angular momentum density can be obtained through the vector mode fluctuations and the corresponding boundary action. We give analytic results of both Hall viscosity and angular momentum density near the critical regime in terms of physical parameters. The near-critical behavior of Hall viscosity is different from that obtained from a gravitational Chern-Simons model. We find that the magnitude of Hall viscosity to angular momentum density ratio is numerically consistent with being equal to 1/2 at large SU(2) coupling corresponding to the probe limit, in agreement with previous results obtained for various quantum fluid systems and from effective theory approaches. In addition, we find the shear viscosity to entropy density ratio remains above the universal bound.
The dilemma of the new-comet flux

The question of the constancy of the flux rate of “new” comets from the Oort cloud is critical in studies of the origin of comets. The large numbers may be explained by our being in a “comet shower” or else by a loss of intrinsic brightness by new comets during their first passage through the inner solar system—hence the dilemma. Improvements in the quality and quantity of reliable orbits now make possible fairly precise evaluation of the data involved in the dilemma and a realistic comparison of the two alternatives. If we are in a comet shower, the increase with respect to the last several tens of thousands of years is not more than a factor of 1.8 nor a magnitude loss during first passage of more than 0m.85. This applies if new comets are defined as those with periods greater than 106 yr. If the limit is set at 2.8 × 106 yr, we may not be really in a comet shower and a good fraction of the comets with periods in the range 106 < P < 2.8 × 106 yr may be returning comets. The Oort cloud would then be fairly stable to nearly 40,000 AU. If we assume the reality of comet fading in the sense that few new comets are observable on their returns when more distant than 3.0 AU from the Sun, and if we then limit the discussion to comets with perihelion distance q < 3.0 AU, there is no evidence for a shower.
Entrainment Mechanisms for Outflows in the L1551 Star-Forming Region

We present high sensitivity 12CO and 13CO J = 1 → 0 maps covering the full extent of the parsec-scale L1551 molecular outflow, including the redshifted east-west (EW) flow. We also present 12CO J = 3 → 2 data obtained over a good fraction of the L1551 outflow. We compare the molecular data to wide-field, narrowband optical emission in Hα. While there are multiple outflows in the L1551 cloud, the main outflow is oriented at 50° position angle and appears to be driven by an embedded source(s) in the central IRS 5 region. The J = 3 → 2 data indicate that there may be molecular emission associated with the L1551 NE jet, within the redshifted lobe of the main outflow. We have also better defined the EW flow and believe we have identified its blueshifted counterpart. We speculate that the origin of the EW outflow lies near HH 102. Velocity-dependent opacity correction is used to estimate the mass and energy of the outflow. The resulting mass spectral indices from our analysis are systematically lower (less steep) than the power-law indices obtained toward other outflows in several recent studies that use a similar opacity correction method. We show that systematic errors and biases in the mass analysis procedures could result in errors in the determination of the power-law indices. The mass spectral indices, the morphological appearance of the position-velocity plots, and integrated intensity maps of molecular data, compared with the optical, suggest that jet-driven bow shock entrainment is the best explanation for the driving mechanism of outflows in L1551. The kinetic energy of the outflows is found to be comparable to the binding energy of the cloud and sufficient to maintain the turbulence in the L1551 cloud.
Rhodium-catalyzed enantioselective desymmetrization of meso-3,5-dimethyl glutaric anhydride: a general strategy to syn-deoxypolypropionate synthons.

A rhodium phosphinooxazoline system allows for an efficient enantioselective desymmetrization of dimethyl glutaric anhydride. Both commercially available and in situ generated sp3-organozinc nucleophiles couple efficiently in high enantiomeric excess. This chemistry has also been extended to other 3,5-disubstituted anhydrides, and further elaboration has enabled the synthesis of potentially useful syn-deoxypolypropionate fragments.
Chemoenzymatic Synthesis of a New Class of Macrocyclic Oligosaccharides

A novel and highly efficient chemoenzymatic method has been developed for the preparation of structurally defined macrocyclic oligosaccharides of varied sizes. This method involves chemical or chemoenzymatic synthesis of oligosaccharides containing a galactose at the nonreducing end and a propargyl group at the reducing end as sialyltransferase acceptors. Introducing an azido-containing sialic acid to the nonreducing end of the galactosides through a sialyltransferase-catalyzed enzymatic reaction followed by copper(I)-catalyzed Huisgen's 1,3-dipolar cycloaddition of alkyne and azide provides size-defined macrocyclic carbohydrates. The produced negatively charged macrocycles have high solubility in water and interact with hydrophobic small molecules in a size-dependent manner.
Practical Palladium Catalysts for C-N and C-O Bond Formation

The development of new palladium catalysts for the arylation of amines and alcohols with aryl halides and sulfonates is reviewed. Initial systems as well as mechanistic issues are discussed briefly, while subsequent generations of catalysts are described in greater detail. For these later generations of catalysts, substrate scope and limitations are also discussed. The review is organized by substrate class. Modifications and improvements in technical aspects of reaction development are described where appropriate. In addition, applications of this technology toward natural product synthesis, new synthetic methodology, and medicinal chemistry are chronicled. This review is organized in a manner that is designed to be useful to the synthetic organic chemist.
Synthesis and biological evaluation of nonclassical 2,4-diamino-5- methylpyrido[2,3-d]pyrimidines with novel side chain substituents as potential inhibitors of dihydrofolate reductases

Nine novel 2,4-diamino-5-methyl-6-substituted-pyrido[2,3-d]pyrimidines, 2−10, were synthesized as potential inhibitors of Pneumocystis carinii dihydrofolate reductase (pcDHFR) and Toxoplasma gondii dihydrofolate reductase (tgDHFR). Compounds 2−5 were designed as conformationally restricted analogues of trimetrexate (TMQ), in which rotation around τ3 was constrained by incorporation of the side chain nitrogen as part of an indoline or an indole ring. Analogue 6, which has an extra atom between the side chain nitrogen and the phenyl ring, has its nitrogen as part of a tetrahydroisoquinoline ring. Analogues 7−9 are epiroprim (Ro 11-8958) analogues and contain a pyrrole ring as part of the side chain substitution on the phenyl ring similar to epiroprim. These analogues were designed to investigate the role of the pyrrole substitution on the phenyl ring of 2,4-diamino-5-methyl-6-(anilinomethyl)pyrido[2,3-d]pyrimidines. Molecular modeling indicated that a pyrrole substituent in the ortho position of the side ch...
Experimentation, Imitation, and Stochastic Stability

Abstract Do boundedly rational agents repeatedly playing a symmetric game with a unique symmetric equilibrium learn over time to play it? In this paper we model the dynamic interaction of two types of such agents, experimenters and imitators, whose behavior is characterized by simple rules of thumb. We find that the stochastic process describing their play isstable in the large: it converges globally and with probability one to a compact neighborhood of the equilibrium. However, its local behavior near the equilibrium depends in interesting ways on the details of the model.Journal of Economic LiteratureClassification Number: D83.
TOWARDS THEORETICAL FOUNDATIONS OF SOFT COMPUTING APPLICATIONS

The original idea of fuzzy logic and other soft computing methodologies was to handle the situations in which our knowledge is not precise. Usually, real numbers are used to describe degrees of belief. In practice, only approximate values of the degrees of belief are known, while the existing soft computing formalisms are usually based on the assumption that we know the exact values of these degrees. This difference creates a gap between the theory and applications. In this paper, we outline the theoretical foundations aimed at bridging this gap.
Heavy-flavor production in LHC pp interactions using the ALICE detector

Abstract Measurements of charm and beauty production in pp collisions, using the ALICE detector system, at LHC energies ( s = 2.76 and 7.0 TeV) can test perturbative QCD down to very low Bjorken-x. They are also critical as a reference to ALICEʼs heavy ion program. The ALICE detector system allows measurements not covered by the other LHC experiments in addition to covering complementary regions. A description of the ALICE detector system, in relation to ATLAS and CMS, are presented. Results from both leptonic and hadronic decay channels will be shown along with comparisons to other measurements when available.
Yamabe Invariants and $ Spin^c $ Structures

The Yamabe invariant of a smooth compact manifold is by definition the supremum of the scalar curvatures of unit-volume Yamabe metrics on the manifold. For an explicit infinite class of 4-manifolds, we show that this invariant is positive but strictly less than that of the 4-sphere. This is done by using $ spin^c $ Dirac operators to control the lowest eigenvalue of a perturbation of the Yamabe Laplacian. These results dovetail perfectly with those derived from the perturbed Seiberg–Witten equations [Le3], but the present method is much more elementary in spirit.
Computers with remote data input

This discussion concerns the current status of remote input technology for commercial data processing installations. It deals with a few of the problems and implications of 1) the electro-mechanical recording of data on a storage media at a remote geographical location, 2) the transmission of the recorded data to a central computer, and 3) the conversion of the transmitted information to a form suitable for computer input. This general purpose approach precludes consideration of special purpose, on-line computer applications.
Stationary Markov chains with linear regressions

In Bryc (Ann. Probab., (1998), to appear), we determined one-dimensional distributions of a stationary field with linear regressions (1) and quadratic conditional variances (2) under a linear constraint (7) on the coefficients of the quadratic expression (3). In this paper, we show that for stationary Markov chains with linear regressions and quadratic conditional variances the coefficients of the quadratic expression are indeed tied by a linear constraint which can take only one of the two alternative forms (7), or (8).
A unified approach to the minimal unitary realizations of noncompact groups and supergroups

We study the minimal unitary representations of non-compact groups and supergroups obtained by quantization of their geometric realizations as quasi-conformal groups and supergroups. The quasi-conformal groups G leave generalized light-cones defined by a quartic norm invariant and have maximal rank subgroups of the form H × SL(2, ) such that G/H × SL(2, ) are para-quaternionic symmetric spaces. We give a unified formulation of the minimal unitary representations of simple non-compact groups of type A2, G2, D4, F4, E6, E7, E8 and Sp(2n, ). The minimal unitary representations of Sp(2n, ) are simply the singleton representations and correspond to a degenerate limit of the unified construction. The minimal unitary representations of the other noncompact groups SU(m, n), SO(m, n), SO*(2n) and SL(m, ) are also given explicitly. We extend our formalism to define and construct the corresponding minimal representations of non-compact supergroups G whose even subgroups are of the form H × SL(2, ). If H is noncompact then the supergroup G does not admit any unitary representations, in general. The unified construction with H simple or Abelian leads to the minimal representations of G(3), F(4) and O Sp(n|2, ) (in the degenerate limit). The minimal unitary representations of O Sp(n|2, ) with even subgroups SO(n) × SL(2, ) are the singleton representations. We also give the minimal realization of the one parameter family of Lie superalgebras D(2, 1; σ).
RADIO OBSERVATIONS REVEAL UNUSUAL CIRCUMSTELLAR ENVIRONMENTS FOR SOME TYPE Ibc SUPERNOVA PROGENITORS

We present extensive radio observations of the nearby Type Ibc supernovae (SNe Ibc) 2004cc, 2004dk, and 2004gq spanning {Delta}t Almost-Equal-To 8-1900 days after explosion. Using a dynamical model developed for synchrotron emission from a slightly decelerated shock wave, we estimate the velocity and energy of the fastest ejecta and the density profile of the circumstellar medium. The shock waves of all three supernovae are characterized by non-relativistic velocities of v-bar approx. (0.1-25)c and associated energies of E Almost-Equal-To (2-10) Multiplication-Sign 10{sup 47} erg, in line with the expectations for a typical homologous explosion. Smooth circumstellar density profiles are indicated by the early radio data and we estimate the progenitor mass-loss rates to be M-dot approx. (0.6-13) x 10{sup -5} M{sub Sun} yr{sup -1} (wind velocity, v{sub w} = 10{sup 3} km s{sup -1}). These estimates approach the saturation limit ( M-dot {approx}10{sup -4} M{sub Sun} yr{sup -1}) for line-driven winds from Wolf-Rayet stars, the favored progenitors of SNe Ibc including those associated with long-duration gamma-ray bursts. Intriguingly, at later epochs all three supernovae show evidence for abrupt radio variability that we attribute to large density modulations (factor of {approx}3-6) at circumstellar radii of r Almost-Equal-To (1-50) Multiplication-Sign 10{sup 16} cm.more » If due to variable mass loss, these modulations are associated with progenitor activity on a timescale of {approx}10-100 years before explosion. We consider these results in the context of variable mass-loss mechanisms including wind clumping, metallicity-independent continuum-driven ejections, and binary-induced modulations. It may also be possible that the SN shock waves are dynamically interacting with wind termination shocks; however, this requires the environment to be highly pressurized and/or the progenitor to be rapidly rotating prior to explosion. The proximity of the density modulations to the explosion sites may suggest a synchronization between unusual progenitor mass loss and the SN explosion, reminiscent of Type IIn supernovae. This study underscores the utility of radio observations for tracing the final evolutionary stage(s) of SN progenitor systems.« less
Smart Building Materials which Prevent Damage or Repair Themselves

We developed designs in which hollow porous fibers filled with chemicals release them into a matrix over time. A coating covering the fibers is degraded by chemicals, pH change, or broken by structural loading, thus, releasing the chemicals. These stimuli for release are the very agents of environmental attack. The design to alleviate cracking consists of hollow porous fiberglass fibers containing crack-closing chemicals. The chemicals are released from the fibers when the outer sheath cracks or the fibers flex due to loading. This is the ideal situation in which the agent of environmental degradation, namely loading, is the stimulus to release the repair chemical. The design to prevent corrosion consists of an anticorrosion chemical in hollow porous polypropylene fibers. Change in chloride ion concentration dissolves the polyol coating and allows the chemical to be released from the fiber wall. The cause of deterioration, change in chloride level which causes corrosion, is the sensor (coating deterioration) and also the activator for the remedial or preventive action (release of anticorrosion chemical). These are distributed systems responding to environmental stimuli for sensing and repairing when and where they are needed. The control of the amount of chemical released is being researched mainly as a function of coating design and also fiber type.
Origins of structural hole traps in hydrogenated amorphous silicon.

The inherently disordered nature of hydrogenated amorphous silicon ($a$-Si:H) obscures the influence of atomic features on the trapping of holes. To address this, we have created a set of over two thousand ab initio structures of $a$-Si:H and explored the influence of geometric factors on the occurrence of deep hole traps using density-functional theory. Statistical analysis of the relative contribution of various structures to the trap distribution shows that floating bonds and ionization-induced displacements correlate most strongly with hole traps in our ensemble.
Stable Storage of Helium in Nanoscale Platelets at Semicoherent Interfaces

He implanted into metals precipitates into nanoscale bubbles that may later grow into voids, degrading the properties of engineering alloys. Using multiscale modeling, we show that a different class of He precipitates may form at semicoherent interfaces: nanoscale platelets. These platelets grow by wetting high-energy interface regions, remain stable under irradiation, and reduce He-induced swelling. Stable storage of He at interfaces may impart unprecedented He resistance to future structural materials.