cssi/SciSciGPT-SciSciNet huggingface dataset:
Analytic relations for magnifications and time delays in gravitational lenses with fold and cusp configurations

Gravitational lensing provides a unique and powerful probe of the mass distributions of distant galaxies. Four-image lens systems with fold and cusp configurations have two or three bright images near a critical point. Within the framework of singularity theory, we derive analytic relations that are satisfied for a light source that lies a small but finite distance from the astroid caustic of a four-image lens. Using a perturbative expansion of the image positions, we show that the time delay between the close pair of images in a fold lens scales with the cube of the image separation, with a constant of proportionality that depends on a particular third derivative of the lens potential. We also apply our formalism to cusp lenses, where we develop perturbative expressions for the image positions, magnifications and time delays of the images in a cusp triplet. Some of these results were derived previously for a source asymptotically close to a cusp point, but using a simplified form of the lens equation whose validity may be in doubt for sources that lie at astrophysically relevant distances from the caustic. Along with the work of Keeton, Gaudi & Petters, this paper demonstrates that perturbation theory plays an important role in theoretical lensing studies.
A practical synthesis of N,N-dimethyl-(6-arylpyrid-2-yl)alkylamines

Described is a multigram synthesis of pyridyl amine ligands, which are being studied for their potential use in commercial processes. A practical scale-up was hindered by benzotriazole byproducts of a Grignard addition. With an improved purification to remove these byproducts and a strategic re-ordering of synthetic steps, an array of N,N-dimethyl-(6-arylpyrid-2-yl)alkylamines was made efficiently on large scales.
Concise Total Synthesis and Stereochemical Revision of all (―)-Trigonoliimines

The concise and enantioselective total syntheses of (−)-trigonoliimines A, B, and C are described. Our unified strategy to all three natural products is based on asymmetric oxidation and reorganization of a single bistryptamine, a sequence of transformations with possible biogenetic relevance. We revise the absolute stereochemistry of (−)-trigonoliimines A, B, and C.
Sequential design of a linear quadratic controller for the Deep Space Network antennas

A linear quadratic controller design procedure is proposed for the NASA Deep Space Network antennas. The procedure is developed for an antenna model divided into tracking and flexible subsystems. Controllers for the flexible and tracking parts are designed separately by adjusting the performance index weights. Ad hoc weights are chosen for the tracking part of the controller and the weights for the flexible part are adjusted. Next, the weights for the tracking part are determined, followed by the flexible controller final tune-up. The controller for the flexible part is designed separately for each mode; thus the design procedure consists of weight adjustment for small-size subsystems. The effect of weights on system performance is a crucial property, and is analytically described in this paper. The procedure is illustrated with the control system design for the DSS-13 antenna.
Early atomic models – from mechanical to quantum (1904–1913)

A complete history of early atomic models would fill volumes, but a reasonably coherent tale of the path from mechanical atoms to the quantum can be told by focusing on the relevant work of three great contributors to atomic physics, in the critically important years between 1904 and 1913: J.J. Thomson, Ernest Rutherford and Niels Bohr. We first examine the origins of Thomson’s mechanical atomic models, from his ethereal vortex atoms in the early 1880’s, to the myriad “corpuscular” atoms he proposed following the discovery of the electron in 1897. Beyond qualitative predictions for the periodicity of the elements, the application of Thomson’s atoms to problems in scattering and absorption led to quantitative predictions that were confirmed by experiments with high-velocity electrons traversing thin sheets of metal. Still, the much more massive and energetic α-particles being studied by Rutherford were better suited for exploring the interior of the atom, and careful measurements on the angular dependence of their scattering eventually allowed him to infer the existence of an atomic nucleus. Niels Bohr was particularly troubled by the radiative instability inherent to any mechanical atom, and succeeded in 1913 where others had failed in the prediction of emission spectra, by making two bold hypotheses that were in contradiction to the laws of classical physics, but necessary in order to account for experimental facts.
Prompt optical emission and synchrotron self-absorption constraints on emission site of GRBs

We constrain the distance of the gamma-ray burst (GRB) prompt emission site from the explosion centre R, by determining the location of the electron's self-absorption frequency in the GRB prompt optical-to-X/γ-ray spectral energy distribution, assuming that the optical and the γ-ray emissions are among the same synchrotron radiation continuum of a group of hot electrons. All possible spectral regimes are considered in our analysis. The method has only two assumed parameters, namely the bulk Lorentz factor of the emitting source r and the magnetic field strength B in the emission region (with a weak dependence). We identify a small sample of four bursts that satisfy the following three criteria: (1) they all have simultaneous optical and γ-ray detections in multiple observational time intervals, (2) they all show temporal correlations between the optical and γ-ray light curves and (3) the optical emission is consistent with belonging to the same spectral component as the γ-ray emission. For all the time intervals of these four bursts, it is inferred that R ≥ 10 14 (Γ/300) 3/4 (B/10 5 G) 1/4 cm. For a small fraction of the sample, the constraint can be pinned down to R ≈ 10 14 ―10 15 cm for Γ ∼ 300. For a second sample of bursts with prompt optical non-detections, only upper limits on R can be obtained. We find no inconsistency between the R-constraints for this non-detection sample and those for the detection sample.
Integrating forest and small-scale farm systems in Middle America☆

Abstract Initial clearing and continued suppression of wild vegetation seem proof that farming and forest are incompatible. Yet many crop plants, like their wild relatives, fare better in species diverse, structurally complex communities. Some small-scale or traditional farmers in Middle America partially recreate forest conditions in their fields to improve edaphic and microclimate conditions. Farmers may either physically transfer forest products or simulate forest structures and nutrient cycles in cultivated fields. The particular strategies adopted depend upon local climatic conditions and crop requirements. Generally, crops requiring high levels of sunlight must be grown in the open, in field rather than forest microclimates. In such cases nearby forests may supply soil conditioning materials such as leaf litter to improve soil structure and nutrient levels. Alternatively, long term forest-farm rotations allow regeneration of forest soils. Where slight reductions of solar radiation are permissible scattered leguminous trees may be tolerated in cultivated fields. If greater protection is desirable at early or all stages of crop plant growth, aspects of forest structure and microclimates may be emulated either individually (e.g., forest litter, undergrowth) or collectively in multi-storied commercial farms or dooryard gardens.
A Cherenkov cyclotron autoresonance maser

A CARM is an efficient source of high-frequency microwaves based on the negative mass instability. The output is Doppler-upshifted beyond the gyrotron frequency by the free electron factor of γ2. By loading the interaction tube with dielectric, the voltage requirements are substantially reduced. Despite the reduced voltage, a significant upshift can still occur
A Census of Baryons in Galaxy Clusters and Groups

We determine the contribution of stars in galaxies, intracluster stars, and the intracluster medium to the total baryon budget in nearby galaxy clusters and groups. We find that the baryon mass fraction (fb ≡ Ωb/Ωm) within r500 is constant for systems with M500 between 6 × 1013 and 1 × 1015 M☉. Although fb is lower than the WMAP value, the shortfall is on the order of both the observational systematic uncertainties and the depletion of baryons within r500 that is predicted by simulations. The data therefore provide no compelling evidence for undetected baryonic components, particularly any that would be expected to vary in importance with cluster mass. A unique feature of the current analysis is direct inclusion of the contribution of intracluster light (ICL) in the baryon budget. With the addition of the ICL to the stellar mass in galaxies, the increase in X-ray gas mass fraction with increasing total mass is entirely accounted for by a decrease in the total stellar mass fraction, supporting the argument that the behavior of both the stellar and X-ray gas components is dominated by a decrease in star formation efficiency in more massive environments. Within just the stellar component, the fraction of the total stellar luminosity in the central, giant brightest cluster galaxy (BCG) and ICL (hereafter the BCG+ICL component) decreases as velocity dispersion (σ) increases for systems with 145 km s-1 ≤ σ ≤ 1026 km s-1, suggesting that the BCG+ICL component, and in particular the dominant ICL component, grows less efficiently in higher mass environments. The degree to which this behavior arises from our sample selection, which favored systems with central, giant elliptical galaxies, remains unclear. A more robust result is the identification of low-mass groups with large BCG+ICL components, demonstrating that the creation of "intracluster" stars does not require a massive cluster environment. Within r500 and r200, the BCG+ICL contributes on average 40% and 33% of the total stellar light, respectively, for the clusters and groups in our sample. Because these fractions are functions of both enclosed radius and system mass, care should be exercised when comparing these values with other studies and simulations.
Tight closure of finite length modules in graded rings

In this article, we look at how the equivalence of tight closure and plus closure (or Frobenius closure) in the homogeneous m-coprimary case implies the same closure equivalence in the nonhomogeneous m-coprimary case in standard graded rings. Although our result does not depend upon dimension, the primary application is based on results known in dimension 2 due to the recent work of H. Brenner. We also demonstrate a connection between tight closure and the m-adic closure of modules extended to R+ or R∞. We finally show that unlike the Noetherian case, the injective hull of the residue field over R+ or R∞ contains elements that are not killed by any power of the maximal ideal of R. This fact presents an obstruction to one possible method of extending our main result to all modules.
A low-leakage VLSI CMOS/SOS process with thin epi layers

A new VLSI process was successfully developed for short-channel CMOS/SOS circuits on thin 0.3μm epi layers. Two kinds of thin epi material were used. The first was grown by a standard CVD process, while the second was prepared by a double solid phase epitaxial regrowth (DSPE) technique. CMOS/SOS ring oscillators with effective channel lengths ranging from 0.7 to 1.3μm were fabricated. Leakage currents below 3.0pA/μm were achieved on both n-channel and p-channel devices. The DSPE material showed improvement in both mobility and speed.
New progress in biomedical polymer materials

Abstract In this highly complex interdisciplinary area of biomedical polymers, progress is beginning to be made in a variety of implants. Of probable major importance is that of small diameter blood vessel repair. The studies leading to the development of a small diameter vascular graft are discussed to show the interrelationship between polymer surface and bulk morphology, polymer-protein interaction, platelet adhesion, and implant mechanical properties on the performance of the implant in the body.
Structural equations modeling: Fit Indices, sample size, and advanced topics

Abstract This article is the second of two parts intended to serve as a primer for structural equations models for the behavioral researcher. The first article introduced the basics: the measurement model, the structural model, and the combined, full structural equations model. In this second article, advanced issues are addressed, including fit indices and sample size, moderators, longitudinal data, mediation, and so forth.
New developments in the organic chemistry of fullerenes

Unlike the addition of a second equivalent of diazoalkane to C60, which does not show marked selectivity, the addition of azides to C60 shows chemo and regio selectivity [4]. Utilization of this unique selectivity, led us to the preparation of the first heterofullerene ‘C59N’ in bulk quantity [5, 6]. Herein we report on its synthesis and mechanism of formation. We also describe the application of this procedure for the formation of higher heterofullerene analogs, i.e. ‘C69N’ isomers [7] and introduce methodology that opens a viable route to the functionalization of azafullerenes [8]. The azafullerene (C59N)2 can be synthesized from C60 in three steps. The initial step in the formation of azafullerenes is the 1,3-dipolar cycloaddition of 2methoxyethoxymethyl azide (MEM-azide) [9]. Not unlike the addition of diazoalkane, the addition of an alkyl azide to C60 occurs across the [6,6] bond. At room temperature, the initially formed triazoline can be isolated in 35-40% yield. Thermolysis of the triazoline, followed by concomitant loss of nitrogen, gives rise to azafulleroids and fulleroaziridines. Fulleroaziridines and azafulleroids can also be obtained directly from C60 at higher reaction temperatures (160-180°C).
Heat Transfer Through a Pressure-Driven Three-Dimensional Boundary Layer

An experimental investigation of heat transfer through a three-dimensional boundary layer has been performed. An initially two-dimensional boundary layer was made three dimensional by a transverse pressure gradient caused by a wedge obstruction, which turned the boundary layer within the plane of the main flow. Two cases, with similar streamwise pressure gradients and different lateral gradients, were studied so that the effect of the lateral gradient on heat transfer could be deduced. The velocity flowfield agreed with previous hydrodynamic investigations of this flow. The outer parts of the mean velocity profiles were shown to agree with the Squire-Winter theorem for rapidly turned flows. Heat transfer data were collected using a constant heat flux surface with embedded thermocouples for measuring surface temperatures. Mean fluid temperatures were obtained using a thermocouple probe. The temperature profiles, when plotted in outer scalings, showed logarithmic behavior consistent with two-dimensional flows. An integral analysis of the boundary layer equations was used to obtain a vector formulation for the enthalpy thickness which is consistent with the scalar formulation used for two-dimensional flows. Using the vector formulation, the heat transfer data agreed with standard two-dimensional correlations of the Stanton number and enthalpy thickness Reynolds number. It was concludedmore » that although the heat transfer coefficient decreased faster than its two-dimensional counterpart, it was similar to the two-dimensional case. The vector form of the enthalpy thickness captured the rotation of the mean thermal energy flux away from the free-stream direction. Boundary layer three dimensionality increased with the strength of the transverse pressure gradient and the heat transfer coefficients were smaller for the stronger transverse gradient.« less
Augustine’s Confessions : The Story of a Divided Self and the Process of Its Unification

This article takes up William James’ observation that Saint Augustine is “a classic example” of the discordant personality or divided self, and employs E. R. Dodd’s equally classic (1927–28) article on Augustine’s “spiritual maladjustment” to explore the psychological bases, especially parental, for Augustine’s discordant personality, and to evaluate the effectiveness of Augustine’s efforts to overcome the discordancy through a personal religious conversion.
THE ANOMALOUS ACCRETION DISK OF THE CATACLYSMIC VARIABLE RW SEXTANTIS

Synthetic spectra covering the wavelength range 900-3000 A provide an accurate fit, established by a {chi}{sup 2} {sub {nu}} analysis, to a combined observed spectrum of RW Sextantis. Two separately calibrated distances to the system establish the synthetic spectrum comparison on an absolute flux basis but with two alternative scaling factors, requiring alternative values of M-dot for final models. Based on comparisons for a range of M-dot values, the observed spectrum does not follow the standard model. Rather than the exponent 0.25 in the expression for the radial temperature profile, a value close to 0.125 produces a synthetic spectrum with an accurate fit to the combined spectrum. A study of time-series Far Ultraviolet Spectroscopic Explorer spectra shows that a proposed warped or tilted disk is not supported by the data; an alternative proposal is that an observed non-axisymmetric wind results from an interaction with the mass transfer stream debris.
Generalized compound scaling algorithm and application to minimum weight design of plate structures

This paper presents the generalized compound scaling algorithm and its application to optimum weight design of plate structures. The optimum designs are reached by simply scaling the design variables to an optimum intersection of multiple constraints. A four-noded isoparametric plate element is used for modeling the structure. Sensitivity computations and the optimization algorithm are discussed. The optimization cost involved (excluding the finite element analyses) is very small using this algorithm. The procedure is demonstrated on three example problems using stress and displacement constraints with side bounds on the design variables.
Trustworthy data from untrusted databases

Ensuring the trustworthiness of data retrieved from a database is of utmost importance to users. The correctness of data stored in a database is defined by the faithful execution of only valid (authorized) transactions. In this paper we address the question of whether it is necessary to trust a database server in order to trust the data retrieved from it. The lack of trust arises naturally if the database server is owned by a third party, as in the case of cloud computing. It also arises if the server may have been compromised, or there is a malicious insider. In particular, we reduce the level of trust necessary in order to establish the authenticity and integrity of data at an untrusted server. Earlier work on this problem is limited to situations where there are no updates to the database, or all updates are authorized and vetted by a central trusted entity. This is an unreasonable assumption for a truly dynamic database, as would be expected in many business applications, where multiple clients can update data without having to check with a central server that approves of their changes. We identify the problem of ensuring trustworthiness of data at an untrusted server in the presence of transactional updates that run directly on the database, and develop the first solutions to this problem. Our solutions also provide indemnity for an honest server and assured provenance for all updates to the data. We implement our solution in a prototype system built on top of Oracle with no modifications to the database internals. We also provide an empirical evaluation of the proposed solutions and establish their feasibility.
The Luminosity Functions and Size Distributions of H II Regions in Irregular Galaxies

CCD Hα images were used to study the properties of H II regions in 29 normal Im galaxies and six blue compact dwarf/starburst irregulars. The Hα emission line fluxes were measured and used to construct luminosity functions for each galaxy. For most galaxies, the luminosity function is well represented by a power law. Only two of the 29 Im galaxies have supergiant H II regions, which is probably a result of the small size and small total numbers of H II regions in irregular galaxies. BCDs and starburst galaxies, on the other hand, do not always have supergiant H II regions but may have them even if only a few regions are present. Comparison of the cumulative composite H II luminosity function with that of spiral galaxies shows that the irregulars in our sample do not have an unusually large population of supergiant H II regions relative to the galactic luminosity. Thus, these galaxies will not suffer a disproportionate amount of disruption by the concentration of massive stars within such regions. However, in BCD/starburst galaxies there is an excess of H II regions with luminosities greater than 1038 ergs s-1 compared to Im and Sc galaxies relative to the luminosities of the host galaxies. Most of the H II region luminosity in normal Im galaxies comes from small regions and that in BCD/starburst galaxies from moderately large regions. Over 80% of the H II region luminosity in irregulars is found in complexes of H II regions typically with summed luminosities equivalent to ≤10 Orion nebulae. Two types of luminosity functions were observed: those that exhibit turnover and those that do not. Those that do exhibit turnover have an average slope of -1.5 ± 0.1, and those that do not exhibit turnover tend to be complete to fainter levels, have lower upper luminosity cutoffs, have fewer H II regions, and have shallower slopes of -1.0 ± 0.1. If the luminosity function is universal for a galaxy type, this difference suggests the possibility of a break in the luminosity function corresponding to H II regions ionized by single stars and H II regions ionized by clusters of stars. However, we cannot exclude the possibility that the two groups of galaxies are different in terms of their global star formation properties. Diameters of H II regions were also measured and diameter distributions were constructed for each of the galaxies. The diameter distribution was fitted with an exponential and the characteristic diameter D0 was measured for each galaxy, although this fit did not characterize the distribution very well in most galaxies. The weak correlation between D0 and the absolute blue magnitude of the galaxy suggested by others is confirmed to be very weak.
Extended solubility and stability in vapor quenched Ni3Al-X intermetallics

A series of fine-grain and amorphous Ni3Al-X alloys, where X is a solute of 1 to 45 at. pct hf, C, or Hf+C in continuously graded compositions, was formed simultaneously into a 0.2 mm-thick disk by high-rate sputter codeposition. The as-deposited Ni3Al-X alloys exhibited a disordered L1(2) structure and extended solid solubility limits beyond which amorphous phases were formed. Heat-treatment of the alloys at 900 C resulted in fine grain size of 0.5 micron to 1.5 microns. Ultra fine dispersoids less than 500 A in size were observed, and they seemed resistant to coarsening.
Magnesium Isotope Ratios in Hyades Stars

Using classical model atmospheres and an LTE analysis, Mg isotope ratios 24Mg:25Mg:26Mg are measured in 32 Hyades dwarfs covering effective temperatures 4000 K ≤ Teff ≤ 5000 K. We find no significant trend in any isotope ratio versus Teff, and the mean isotope ratio is in excellent agreement with the solar value. We determine stellar parameters and Fe abundances for 56 Hyades dwarfs covering 4000 K ≤ Teff ≤ 6200 K. For stars warmer than 4700 K, we derive a cluster mean value of [Fe/H] = 0.16 ± 0.02 (σ = 0.1), in good agreement with previous studies. For stars cooler than 4700 K, we find that the abundance of Fe from ionized lines exceeds the abundance of Fe from neutral lines. At 4700 K, [Fe/H]II - [Fe/H]I 0.3 dex, while at 4000 K [Fe/H]II - [Fe/H]I 1.2 dex. This discrepancy between the Fe abundance from neutral and ionized lines likely reflects inadequacies in the model atmospheres and the presence of non-LTE or other effects. Despite the inability of the models to reproduce the ionization equilibrium for Fe, the Mg isotope ratios appear immune to these problems and remain a powerful tool for studying Galactic chemical evolution.
Turbulence and fossil turbulence lead to life in the universe

Turbulence is defined as an eddy-like state of fluid motion where the inertial-vortex forces of the eddies are larger than all the other forces that tend to damp the eddies out. Fossil turbulence is a perturbation produced by turbulence that persists after the fluid ceases to be turbulent at the scale of the perturbation. Because vorticity is produced at small scales, turbulence must cascade from small scales to large, providing a consistent physical basis for Kolmogorovian universal similarity laws. Oceanic and astrophysical mixing and diffusion are dominated by fossil turbulence and fossil turbulent waves. Observations from space telescopes show turbulence and vorticity existed in the beginning of the universe and that their fossils persist. Fossils of big bang turbulence include spin and the dark matter of galaxies: clumps of ∼1012 frozen hydrogen planets that make globular star clusters as seen by infrared and microwave space telescopes. When the planets were hot gas, they hosted the formation of life in a cosmic soup of hot-water oceans as they merged to form the first stars and chemicals. Because spontaneous life formation according to the standard cosmological model is virtually impossible, the existence of life falsifies the standard cosmological model.
Sharp L^2 bounds for oscillatory integral operators with C^\infty phases

Let T be an oscillatory integral operator on L^2(R) with a smooth real phase function S(x,y). We prove that, in all cases but the one described below, after localization to a small neighborhood of the origin the norm of T decays like N^{-d/2} as the frequency N->infty, where d is the Newton decay rate introduced by Phong and Stein, which is determined by the Newton diagram of S(x,y). For real analytic phase functions this result was proved by Phong and Stein. For smooth phase functions the best known results so far contained a loss of epsilon in the exponent (implicit in the work of Seeger). The exceptional case mentioned above happens when the Taylor series of the mixed partial derivative S''(x,y) factorizes in R[[x,y]] as U(x,y)(y-f(x))^k, where U(x,y) is a unit, k\ge 2, and f(x) is a series in R[[x]] of the form Cx+(higher order), C\ne 0. In this case we prove an estimate with a loss of of a power of log N.
Growth and characterization of CuGaS2, CuAlS2 and CuGa0.9Al0.1S2 single crystals

Abstract In the search for suitable chalcogenides which may be used as infrared windows at 10μm, several chalcogenides of copper, gallium and aluminum have been investigated. Single crystals of CuGaS 2 , CuAlS 2 and CuGa 0.9 Al 0.1 S 2 have been grown by chemical vapor transport using iodine as the transport agent. They all crystallize with the chalcopyrite structure. The energy gap, infrared transmission, stability in oxygen and microhardness have been measured for these compounds. CuAlS 2 has higher thermal stability and hardness than CuGaS 2 , but its IR transmission range is smaller. The IR transmission range of the 10% solid solution lies between those of the two end members; its thermal stability and optical band gap are lower than those of both end members.
A formal approach to score normalization for meta-search

Meta-search, or the combination of the outputs of different search engines in response to a query, has been shown to improve performance. Since the scores produced by different search engines are not comparable, researchers have often decomposed the meta-search problem into a score normalization step followed by a combination step. Combination has been studied by many researchers. While appropriate normalization can affect performance, most of the normalization schemes suggested are ad hoc in nature. In this paper, we propose a formal approach to normalizing scores for meta-search by taking the distributions of the scores into account. Recently, it has been shown that for search engines the score distributions for a given query may be modeled using an exponential distribution for the set of non-relevant documents and a normal distribution for the set of relevant documents. Here, it is shown that by equalizing the distributions of scores of the top non-relevant documents the best meta-search performance reported in the literature is obtained. Since relevance information is not available apri-ori, we discuss two different ways of obtaining a good approximation to the distribution of scores of non-relevant documents. One is obtained by looking at the distribution of scores of all documents. The second is obtained by fitting a mixture model of an exponential and a Gaussian to the scores of all documents and using the resulting exponential distribution as an estimate of the non-relevant distribution. We show with experiments on TREC-3, TREC-4 and TREC-9 data that the best combination results are obtained by averaging the parameters obtained from these approximations. These techniques work on a variety of different search engines including vector space search engines like SMART and probabilistic search engines like INQUERY. The problem of normalization is important in many other areas including information filtering, topic detection and tracking, multilingual search and distributed retrieval. Thus, the techniques proposed here are likely to be applicable to many of these tasks.
Infrared laser spectroscopy of molecular ions.

The development of new techniques for infrared laser spectroscopy of molecular ions has resulted in an explosion of high-quality data for important charged molecules. Velocity modulation laser spectroscopy, which exploits the motions of charged particles in electrical plasmas to eliminate interference from neutral absorbers, is rapidly producing a large body of new results for both positive and negative molecular ions. This information will have an important impact on chemistry, biology, and astrophysics. 26 references, 2 figures.
Spitzer Limits on Dust Emission and Optical Gas Absorption Variability around Nearby Stars with Edge-on Circumstellar Disk Signatures

We present Spitzer infrared spectroscopic and photometric observations and McDonald Observatory Smith Telescope and AAT high spectral resolution optical observations of four nearby stars with variable or anomalous optical absorption, likely caused by circumstellar material. The optical observations of Ca II and Na I cover a 2.8 yr baseline and extend the long-term monitoring of these systems by previous researchers. In addition, minisurveys of the LISM around our primary targets provide a reconstruction of the intervening LISM along the line of sight. We confirm that the anomalous absorption detected toward ? Oph is not due to circumstellar material, but to a small filamentary cloud <14.3 pc from the Sun. The three other primary targets, ? Car, HD 85905, and HR 10, show both short- and long-term variability, and little of the observed absorption can be attributed to the LISM along the line of sight. The Spitzer photometry and spectroscopy did not detect infrared excesses. For the three disk stars, we fit the maximum hypothetical infrared excess that is consistent with observed upper limits. We place upper limits on any possible fractional infrared luminosity, LIR/L < (2-5) ? 10-6. These fractional luminosities are significantly less than that found toward ? Pic but comparable to other debris disks. No stable gas absorption component centered at the radial velocity of the star is detected, consistent with no infrared excess detections. Based on simple assumptions of the variable gas absorption component, we estimate limits on the circumstellar gas mass causing the variable absorption: (0.4-20) ? 10-8 M?. These multiwavelength observations place strong limits on any possible circumstellar dust, while confirming variable circumstellar gas absorption, and therefore are interesting targets to explore the origins and evolution of variable circumstellar gas.
Threshold gain temperature dependence of composite resonator vertical-cavity lasers

Vertical-cavity surface-emitting lasers (VCSELs) with two optically coupled but electrically isolated cavities form composite resonator vertical-cavity lasers (CRVCLs). These devices may lase at one of two wavelengths depending on the bias conditions to the two cavities and temperature. A model of the modal gain is presented, which explains the lasing wavelength at threshold based on the spatial and spectral overlap of the microcavity optical modes with the two gain regions.
WMAP polarization results

Abstract The Wilkinson Microwave Anisotropy Probe (WMAP) has mapped the full sky in Stokes I, Q, and U parameters at frequencies 23, 33, 41, 61, and 94 GHz. We detect correlations between the temperature and polarization maps significant at more than 10 standard deviations. The correlations are inconsistent with instrument noise and are significantly larger than the upper limits established for potential systematic errors. Correlations on small angular scales are consistent with the the signal expected from adiabatic initial conditions. We detect excess power on large angular scales consistent with an early epoch of reionization. A model-independent fit to reionization optical depth yields results consistent with the best-fit ΛCDM model, with best-fit value τ=0.17±0.04 at 68% confidence, including systematic and foreground uncertainties.
Effects of LY150720 (picenadol), a novel mixed-action opioid, on schedule-controlled responding in the squirrel monkey

The opioid LY150720 is a racemic mixture whose resolution results in a highly stereospecific separation of agonist and antagonist activity. The effects of LY150720 (0.3-3.0 mg/kg), its agonist (dextro) isomer LY136596 (0.3-1.7 mg/kg) and morphine (0.03-1.0 mg/kg) were studied alone and in combination with naloxone (0.001-1.0 mg/kg) in squirrel monkeys whose responding was maintained under a multiple fixed-ratio 30-response fixed-interval 5-minute (mult FR-30 FI 5-min) schedule of food presentation. LY150720, LY136596 and morphine generally decreased responding under both schedule components, although in several instances increases in responding under the FI component were noted, particularly following LY150720 and LY136596. Naloxone (0.1-3.0 mg/kg) generally had little effect on responding, whereas the antagonist (levo) isomer LY136595 (0.3-10.0 mg/kg) decreased responding under both schedule components. The rate-decreasing effects of morphine, LY150720 and LY136596 were reversed by naloxone; doses of naloxone required to reverse the effects of all three drugs were comparable. When combined with morphine, naloxone restored rates and patterns of responding to control values, whereas combinations of LY150720 or LY136596 and naloxone increased responding under the FI component in excess of control values. These increases appear to be due to anticholinergic actions of LY150720 and LY136596, as they are reversed by physostigmine (0.01 mg/kg) and similar increases are produced by scopolamine (0.01-0.1 mg/kg).
The Value and Applicability of Bargaining in an Intergenerational Setting

Abstract This paper considers the effectiveness of a variation of Coasian bargaining as a policy instrument for internalizing one or multiple intergenerational externalities. The variation involves appointing a contemporary party to represent the interests of the affected parties who are currently unable to represent themselves. Potential criticisms of such a policy are considered and addressed, and precedents to such a policy are put forth. To test the value of such a policy, a two-period model in which two externalities exist in the production/consumption decisions and with representative agents is used to compare the welfare effects of four scenarios: 1) Agents in each period optimize their period-specific utility, 2) a benevolent social planner chooses allocations in both periods to maximize a social welfare function, 3) the externalities are internalized using a bargaining policy, and 4) the externalities are internalized using a tax and subsidy policy. I find that, contrary to general consensus in the literature, Coasian bargaining can be adapted in such a way as to make it applicable in an intergenerational framework.
Davis—Greenstein alignment of oblate spheroidal grains

We present extensive calculations on the efficiency of grain alignment by the Davis–Greenstein (DG) mechanism. We model the grains as oblate spheroids with arbitrary axis ratios. Our description of the grain dynamics includes (i) magnetic dissipation and the inverse process driven by thermal fluctuations in the grain magnetization, (ii) gas–grain collisions and thermal evaporation of molecules from the grain surface, (iii) the transformation of rotational energy into heat by the Barnett effect and the inverse process driven by thermal fluctuations, and (iv) rapid Larmor precession of the grain angular momentum about the interstellar magnetic field. For ordinary paramagnetic grains, we calculate the Rayleigh reduction factor, R, for >1000 combinations of the three dimensionless parameters which characterize the alignment. For superparamagnetic grains, we calculate R from an exact analytic solution for the relevant distribution function. Our results are compared with classical studies of DG alignment, which did not include the Barnett effect. We calibrate the accuracy of a recently proposed perturbative approximation, which includes the Barnett effect, and show that it yields R values with a mean error of ≈ 17 per cent.
Evolution of community structure in the world trade web

In this note we study the bilateral merchandise trade flows between 186 countries over the 1948–2005 period using data from the International Monetary Fund. We use the network visualization package Pajek to identify network structure and behavior across thresholds and over time. In particular, we focus on the evolution of trade “islands” in a world trade network in which countries are linked with directed edges weighted according to the fraction of total dollars sent from one country to another. We find mixed evidence for globalization.
Inaccuracy, Underreporting of Injury, and Lack of Training in Death Certificates

OBJECTIVE: Death certificates are a common data source for injury research, but their legitimacy depends on proper completion by physicians (MDs). We sought to assess MD accuracy and training in completion of death certificates. METHODS: We tested the ability of 361 MDs at a University hospital to complete a sample death certificate. The test was conducted via an anonymous web-based system. We questioned MDs regarding the type of death certificate instruction they had received. The test included a description of a patient with a death due to intracranial bleeding after a fall, and the MDs completed a mock death certificate. Language: en
Fetal breathing movements and lung hypoplasia: Preliminary human observations

Abstract Hypoplasia of the fetal lung is found in association with long-standing oligohydramnios. In animal models, interference with fetal breathing activity has led to lung hypoplasia. It has been suggested that lung hypoplasia associated with oligohydramnios is due to inhibition of fetal breathing. Observations of seven patients with prolonged oligohydramnios, three of whom had lung hypoplasia, indicate that fetal breathing does occur in these cases and that it is unlikely that lung hypoplasia is merely the result of absent fetal breathing activity. In fact, when compared to the four patients with oligohydramnios and presumably normal lungs, the three patients with oligohydramnios and lung hypoplasia spent more time breathing and did so at higher rates.
Palladium-Catalyzed α-Arylation of Azlactones to Form Quaternary Amino Acid Derivatives

The synthesis of α-aryl-α-alkyl amino acid derivatives from α-amino acids by the arylation of azlactone derivatives is reported. Arylation of azlactones derived from alanine, valine, phenalanine, phenyl glycine, and leucine all provided good yields of the arylated product. Mechanistic studies of this reaction revealed that a stable complex containing a ligand formed by reaction of dba with the azlactone accounts for a new inhibiting effect of dba when reactions are initiated with Pd(dba)2.
Sky Variability in the y Band at the LSST Site

We have measured spatial and temporal variability in the y-band sky brightness over the course of four nights above Cerro Tololo near Cerro Pachon, Chile, the planned site for the Large Synoptic Survey Telescope (LSST). Our wide-angle camera lens provided a 41° field of view and a 145'' pixel scale. We minimized potential system throughput differences by deploying a deep-depletion CCD and a filter that matches the proposed LSST y3 band (970 -1030 nm). Images of the sky exhibited coherent wave structure, attributable to atmospheric gravity waves at 90 km altitude, creating 3%-4% rms spatial sky flux variability on scales of about 2° and larger. Over the course of a full night, the y3 band additionally showed highly coherent temporal variability of up to a factor of 2 in flux. We estimate the mean absolute sky level to be approximately y3 = 17.8 mag(Vega), or y3 = 18.3 mag(AB). While our observations were made through a y3 filter, the relative sky brightness variability should hold for all proposed y bands, whereas the absolute levels should more strongly depend on spectral response. The spatial variability presents a challenge to wide-field cameras that require illumination correction strategies that make use of stacked sky flats. The temporal variability may warrant an adaptive y band imaging strategy for LSST, to take advantage of times when the sky is darkest.
Palladium-catalyzed asymmetric [3+2] cycloaddition of trimethylenemethane with imines.

The transition metal-catalyzed trimethylenemethane [3+2] cycloaddition provides a direct route to functionalized heterocycles. Herein, we describe a catalytic, asymmetric protocol for the reaction between 3-acetoxy-2-trimethylsilylmethyl-1-propene and various imines. The corresponding pyrrolidines were obtained in excellent yields and enantioselectivities making use of the novel phosphoramidite L10.
A deterministic view of random sampling and its use in geometry

The combination of divide-and-conquer and random sampling has proven very effective in the design of fast geometric algorithms. A flurry of efficient probabilistic algorithms have been recently discovered, based on this happy marriage. We show that all those algorithms can be derandomized with only polynomial overhead. In the process we establish results of independent interest concerning the covering of hypergraphs and we improve on various probabilistic bounds in geometric complexity. For example, givenn hyperplanes ind-space and any integerr large enough, we show how to compute, in polynomial time, a simplicial packing of sizeO(r d ) which coversd-space, each of whose simplices intersectsO(n/r) hyperplanes.
The cosmology of a fundamental scalar

We observe that the standard homogeneous cosmologies, those of Minkowski, de Sitter, and anti-de Sitter, which form the matrix for the Robertson–Walker scale factor, live naturally as isolated points inside a larger family of conformally flat metrics obtained by allowing a tensor containing the information of conformal symmetry breaking to be more general. So the standard cosmological metrics are parametrically unstable in this sense, and therefore unphysical. When we pass to the stable family of perturbed metrics, we immediately encounter a scalar field, which drives the conformal expansion of the universe and which automatically obeys the non-linear sine-Gordon equation. The Lagrangian for the sine-Gordon equation is a cosine potential agreeing to the fourth order with the potential used in the approach to the generation of mass in gauge theories. Accordingly we identify our geometric scalar field—actually of the type of an abelian gauge field—with the recently discovered scalar field. There are two constants in the theory: the first, named \(m\), is positive and defines a mass scale for the universe; the second, named \(\varLambda \), is the cosmological constant. For the space–time to be everywhere non-singular, equivalently for the (strict) dominant energy condition to hold, these constants must obey the inequality \(\varLambda > m^2/4\).
The assessment of fecal incontinence in women.

Fecal incontinence is a common problem in women after vaginal delivery. Overt sphincter damage from a third or fourth degree tear occurs in approximately 0.6% to 3% of women undergoing vaginal delivery. Twenty-nine percent to 48% of these patients develop anal incontinence between 3 months and 3 years after primary sphincter repair. Between 6.8% and 35% of primiparal and 12% and 44% of multiparal women have occult sphincter damage recognized on endoanal ultrasonography (EAUS) (Table 1). From one-third to two-thirds of women with such sphincter damage recognized on EAUS have bowel symptoms such as urgency or anal incontinenence. After vaginal delivery pudendal nerve conduction can also be impaired. Prolonged pudendal nerve terminal motor latency (PNTML) is thought to occur in 42% of women who undergo vaginal delivery. Subsequent recovery is noted in 60% of these patients within the first 2 months after delivery. Muscular and neurologic damage may also coexist. Indeed 60% of incontinent women who have sustained an obstetric injury to the external anal sphincter have prolonged PNTML. Both severity and the prevalence of fecal incontinence increase with age, suggesting that other factors may also be involved. A progressive denervation of the anal sphincter muscles may be responsible for the delayed onset of fecal incontinence. But no clear correlation can be demonstrated between the weakness of the external anal sphincter and PNTML in elderly incontinent patients. These findings suggest that in this population a contribution to the weakness of external anal sphincter may be a decrease in the activity of the anterior horn cells in the spinal cord or the reduction in upper motor neurons caused by old age. The reduction in strength of the connective tissue fascia that occurs with the decline of estrogen production at menopause might weaken the pelvic floor and exacerbate any tendency to pudendal neuropathy caused by obstetric factors. This plethora of contributors mandates accurate assessment of anorectal and pelvic floor function in women with fecal incontinence to correctly identify the cause of the incontinence and to plan the most appropriate treatment.
Quark-Antiquark Bound States within a Dyson-Schwinger Bethe-Salpeter Formalism

Pion and kaon observables are calculated using a Dyson-Schwinger Bethe-Salpeter formalism. It is shown that an infrared finite gluon propagator can lead to quark confinement via generation of complex mass poles in quark propagators. Observables, including electromagnetic form factors, are calculated entirely in Euclidean metric for spacelike values of bound state momentum and final results are extrapolated to the physical region.
Micellar hydrolysis of hydroxamic acids. Michaelis‐menten kinetics

Rates of reaction for the alkaline hydrolysis of various hydroxamic acids in the presence of cetyltrimethylammonium bromide have been determined. Empirical reaction orders of zero, one-half, and one were found for the hydroxamic acids depending upon reaction conditions and substrate structure. N-methylhydroxamic acids exhibited only first-order kinetics. The results are consistent with the Michaelis-Menten rate equation.
Effect of elliptically polarized light on the angular distribution of photoelectrons

The angular distribution of photoelectrons predicted for elliptically polarized light is shown to be the same as that predicted for partially polarized light having incoherent perpendicular electric field components equal to the electric field components along the major and minor axes of the ellipse.