cssi/SciSciGPT-SciSciNet huggingface dataset:
Geostatistics as Measures of Spatial Segregation.

Traditional measures of segregation, such as the index of dissimilarity, have been criticized as aspatial in nature. Spatial measures of segregation have been proposed, but they are difficult to use. Based on the idea that segregation implies a spatial separation of ethnic groups, the degree of spatial correlation among groups can reflect the level of segregation. This paper suggests that several geostatistical measures, especially the standard deviational ellipse, are effective tools for capturing the spatial characteristics of a population group. By comparing the ellipses of different groups, measures of segregation can be derived. The paper demonstrates this approach to measuring segregation by way of both a simulation and a case study. [Key words: spatial segregation, geostatistics, deviational ellipses, spatial correspondence/correlation.]
Layer data organization for visualizing unstructured-grid data

Unstructured grid discretizations have become increasingly popular for computational modeling of engineering problems involving complex geometries. However, the use of 3D unstructured grids complicates the visualization task, since the resulting data sets are irregular both geometrically and topologically. The need to store and access additional information about the structure of the grid can lead to visualization algorithms which incur considerable memory and computational overhead. These issues become critical with large data sets. In this paper, we present a layer data organization technique for data from 3D aerodynamics simulations using unstructured grids. This type of simulations typically model air flow surrounding an aircraft body, and the grid resolutions are very fine near the aircraft body. Scientists are usually interested in visualizing the flow pattern near the wing, sometimes very close to the wing surface. We have designed an efficient way to generate the layer representation, and experimented it with different visualization methods, form isosurface rendering, volume rendering to texture-based vector-field visualization. We found that the layer representation facilitates interactive exploration and helps scientists to quickly find regions of interest.
Quasars Are Not Light-Bulbs: Testing Models of Quasar Lifetimes with the Observed Eddington Ratio Distribution

We use the observed distribution of Eddington ratios as a function of supermassive black hole (BH) mass to constrain models of quasar/active galactic nucleus (AGN) lifetimes and light curves. Given the observed (well constrained) AGN luminosity function, a particular model for AGN light curves L(t) or, equivalently, the distribution of AGN lifetimes (time above a given luminosity t(>L)) translates directly and uniquely (without further assumptions) to a predicted distribution of Eddington ratios at each BH mass. Models for self-regulated BH growth, in which feedback produces a self-regulating decay or blowout phase after the AGN reaches some peak luminosity/BH mass and begins to expel gas and shut down accretion, make specific predictions for the light curves/lifetimes, distinct from, e.g., the expected distribution if AGN simply shut down by gas starvation (without feedback) and very different from the prediction of simple phenomenological light bulb scenarios. We show that the present observations of the Eddington ratio distribution, spanning nearly 5 orders of magnitude in Eddington ratio, 3 orders of magnitude in BH mass, and redshifts z = 0-1, agree well with the predictions of self-regulated models, and rule out phenomenological light bulb or pure exponential models, as well as gas starvation models, at high significance (~5?). We also compare with observations of the distribution of Eddington ratios at a given AGN luminosity, and find similar good agreement (but show that these observations are much less constraining). We fit the functional form of the quasar lifetime distribution and provide these fits for use, and show how the Eddington ratio distributions place precise, tight limits on the AGN lifetimes at various luminosities, in agreement with model predictions. We compare with independent estimates of episodic lifetimes and use this to constrain the shape of the typical AGN light curve, and provide simple analytic fits to these for use in other analyses. Given these constraints, the average local BH must have gained its mass in no more than a couple of bright, near peak-luminosity episodes, in agreement with models of accretion triggering in interactions and mergers.
ON THE ACCURACY OF WEAK-LENSING CLUSTER MASS RECONSTRUCTIONS

We study the bias and scatter in mass measurements of galaxy clusters resulting from fitting a spherically symmetric Navarro, Frenk, & White model to the reduced tangential shear profile measured in weak-lensing (WL) observations. The reduced shear profiles are generated for 104 cluster-sized halos formed in a ?CDM cosmological N-body simulation of a 1?h ?1 Gpc box. In agreement with previous studies, we find that the scatter in the WL masses derived using this fitting method has irreducible contributions from the triaxial shapes of cluster-sized halos and uncorrelated large-scale matter projections along the line of sight. Additionally, we find that correlated large-scale structure within several virial radii of clusters contributes a smaller, but nevertheless significant, amount to the scatter. The intrinsic scatter due to these physical sources is 20% for massive clusters and can be as high as 30% for group-sized systems. For current, ground-based observations, however, the total scatter should be dominated by shape noise from the background galaxies used to measure the shear. Importantly, we find that WL mass measurements can have a small, 5%-10%, but non-negligible amount of bias. Given that WL measurements of cluster masses are a powerful way to calibrate cluster mass-observable relations for precision cosmological constraints, we strongly emphasize that a robust calibration of the bias requires detailed simulations that include more observational effects than we consider here. Such a calibration exercise needs to be carried out for each specific WL mass estimation method, as the details of the method determine in part the expected scatter and bias. We present an iterative method for estimating mass M 500c that can eliminate the bias for analyses of ground-based data.
Parameter identification in models of hydrologic systems using the digital simulation language PDEL

Hydrologic systems, like most environmental systems, are usually characterized by partial differential equations. In order to develop a suitable mathematical model for the analysis of such systems, it is first necessary to make use of observed data in order to identify or estimate the system parameters. The digital simulation language PDEL has been extended so as to facilitate this type of parameter identification. The extended version of the language has been named PDEL-ID. In this paper, two hydrologic modeling problems taken from recent water-resources studies are used as examples to illustrate the parameter identification facilities of PDEL. The solution of these two problems demonstrates that little programming effort and virtually no knowledge of optimization techniques are required.
Lattice isomorphisms of bisimple monogenic orthodox semigroups

Using the classification and description of the structure of bisimple monogenic orthodox semigroups obtained by the author (in Semigroup Forum 78, 310–325, 2009), we prove that every bisimple orthodox semigroup generated by a pair of mutually inverse elements of infinite order is strongly determined by the lattice of its subsemigroups in the class of all semigroups. This theorem substantially extends an earlier result of Shevrin (in Simon Stevin 67, 49–53, 1993) stating that the bicyclic semigroup is strongly lattice determined.
Urban Network Gridlock: Theory, Characteristics, and Dynamics

This study explores the limiting properties of network-wide traffic flow relations under heavily congested conditions in a large-scale complex urban street network; these limiting conditions are emulated in the context of dynamic traffic assignment (DTA) experiments on an actual large network. The primary objectives are to characterize gridlock and understand its dynamics. This study addresses a gap in the literature with regard to the existence of exit flow and recovery period. The one-dimensional theoretical Network Fundamental Diagram (NFD) only represents steady-state behavior and holds only when the inputs change slowly in time and traffic is distributed homogenously in space. Also, it does not describe the hysteretic behavior of the network traffic when a gridlock forms or when network recovers. Thus, a model is proposed to reproduce hysteresis and gridlock when homogeneity and steady-state conditions do not hold. It is conjectured that the network average flow can be approximated as a non-linear function of network average density and variation in link densities. The proposed model is calibrated for the Chicago Central Business District (CBD) network. We also show that complex urban networks with multiple route choices, similar to the idealized network tested previously in the literature, tend to jam at a range of densities that are smaller than the theoretical average network jam density. Also it is demonstrated that networks tend to gridlock in many different ways with different configurations. This study examines how mobility of urban street networks could be improved by managing vehicle accumulation and redistributing network traffic via strategies such as demand management and disseminating real-time traveler information (adaptive driving). This study thus defines and explores some key characteristics and dynamics of urban street network gridlocks including gridlock formation, propagation, recovery, size, etc.
A Mechanistically Guided Design Leads to the Synthesis of an Efficient and Practical New Reagent for the Highly Enantioselective, Catalytic Dihydroxylation of Olefins

[structure: see text] The catalytic asymmetric dihydroxylation of olefins has been accomplished with high enantioselectivities using a proline-based catalyst. The pre-transition-state assembly for styrene is shown.
Elastic softening of amorphous and crystalline Li–Si Phases with increasing Li concentration: A first-principles study

Abstract Knowledge of the elastic properties of Li–Si alloys as a function of Li concentration is crucial in the development of reliable deformation and fracture mechanics models for Si anodes in Li-ion batteries. Here, we have studied these properties using first-principles calculations for both amorphous and crystalline phases observed during lithiation of Si anodes. In the case of crystalline alloys, we present the anisotropic elastic tensors as well as the homogenized Young's, shear, and bulk moduli and the Poisson's ratios. We find that while these moduli decrease in an approximately linear manner with increasing Li concentration leading to significant elastic softening (by about one order of magnitude) in both crystalline and amorphous systems, the Poisson's ratios remain in the range of 0.05–0.20 and 0.20–0.30 in the case of crystalline and amorphous systems, respectively. Further, for a given Li concentration, we find that the amorphous structures are elastically somewhat softer than their crystalline counterparts, the difference being more significant (about 30–40%) in Li-poor phases. Our results underscore the importance of including the concentration dependence of elastic constants in the analysis of stress and deformation fields during lithiation and de-lithiation of Si anodes.
Shortest path poset of Bruhat intervals

We define the shortest path poset SP(u,v) of a Bruhat interval [u,v], by considering the shortest u---v paths in the Bruhat graph of a Coxeter group W, where u,v?W. We consider the case of SP(u,v) having a unique rising chain under a reflection order and show that in this case SP(u,v) is a Gorenstein? poset. This allows us to derive the nonnegativity of certain coefficients of the complete cd-index. We furthermore show that the shortest path poset of an irreducible, finite Coxeter group exhibits a symmetric chain decomposition.
Adding predicate argument structure to the Penn TreeBank

This paper presents our basic approach to creating Proposition Bank, which involves adding a layer of semantic annotation to the Penn English TreeBank. Without attempting to confirm or disconfirm any particular semantic theory, our goal is to provide consistent argument labeling that will facilitate the automatic extraction of relational data. An argument such as the window in John broke the window and in The window broke would receive the same label in both sentences. In order to ensure reliable human annotation, we provide our annotators with explicit guidelines for labeling all of the syntactic and semantic frames of each particular verb. We give several examples of these guidelines and discuss the inter-annotator agreement figures. We also discuss our current experiments on the automatic expansion of our verb guidelines based on verb class membership. Our current rate of progress and our consistency of annotation demonstrate the feasibility of the task.
Network protection with multiple availability guarantees

Abstract This paper develops a novel network protection scheme that provides guarantees on both the fraction of time a flow has full connectivity, as well as a quantifiable minimum grade of service during downtimes. In particular, a flow can be below the full demand for at most a maximum fraction of time; if after a network failure the flow is below its full demand, it must still support at least a fraction q of that demand. This is in contrast to current protection schemes that offer either availability-guarantees with no bandwidth guarantees during the downtime, or full protection schemes that offer 100% availability after a single link failure. We show that the multiple availability guaranteed problem is NP-Hard, and develop an optimal solution in the form of an MILP. If a connection is allowed to drop to 50% of its bandwidth for just 1 out of every 20 failures, then a 24% reduction in spare capacity can be achieved over traditional full protection schemes. Allowing for more frequent drops to partial flow, additional savings can be achieved. Algorithms are developed to provision resources for connections that provide multiple availability guarantees for both the sharing and non-sharing case. For the case of q = 0 , corresponding to the standard availability constraint, an optimal pseudo-polynomial time algorithm is presented.
Trade-mediated biotechnology transfer and its effective absorption: an application to the U.S. forestry sector

Abstract In this paper, we analyze the consequences of biotechnology innovations in the United States forest sector (logging) by modeling technology transfer embodied in trade flows and its absorption. A seven-region, seven-traded-commodity version of a dynamic computable general equilibrium model is used to achieve this task. A 0.63% Hicks-neutral biotechnological progress in the source region (U.S.) has differential impacts on the productivity of the log-using sectors in the domestic as well as in the recipient regions. Since recipient regions' ability to utilize biotechnology innovations depends on their absorptive capacity (AC) and structural similarity (SS), we construct the AC and SS indices based on multiplicity of factors such as human capital endowments, skill content and social appropriateness of the new innovations. The model results show that biotechnological innovations in the U.S. forest sector result in a significant increase in timber production. Following the productivity improvements and its embodied spillover, wood products and pulp and paper sectors in the U.S. register higher productivity growth. The role of AC and SS in capturing technical change is shown to be evident. In the face of growing regulations on timber production from public forests, increasing productivity through biotechnology may be the most effective way to meet the consumer demand for forest products.
Spatial-spectral sensing using the Shrink & Match algorithm in asynchronous MIMO OFDM signals

In this paper, we formulate a cognitive radio (CR) systems spectrum sensing (SS) problem in which Secondary Users (SU), with multiple receive antennae, sense a channel shared among multiple asynchronous Primary Users (PU) transmitting Multiple Input Multiple Output (MIMO) Orthogonal Frequency Division Multiplexing (OFDM) signals. The method we propose to estimate the opportunities available to the SUs combines advances in array processing and compressed channel sensing, and leverages on both the so called “shrinkage method” as well as on an over-complete basis expansion of the PUs interference covariance matrix to detect the occupied and idle angles of arrivals and subcarriers. The covariance “shrinkage” step and the sparse modeling step that follows, allow to resolve ambiguities that arise when the observations are scarce, reducing the sensing cost for the SU, thereby increasing its spectrum exploitation capabilities compared to competing sensing methods. Simulations corroborate these claims.
Random inscribing polytopes

For convex bodies K with C^2 boundary in R^d, we explore random polytopes with vertices chosen along the boundary of K. In particular, we determine asymptotic properties of the volume of these random polytopes. We provide results concerning the variance and higher moments of this functional, as well as an analogous central limit theorem.
A differential semantics for jointree algorithms

A new approach to inference in belief networks has been recently proposed, which is based on an algebraic representation of belief networks using multi-linear functions. According to this approach, belief network inference reduces to a simple process of evaluating and differentiating multilinear functions. We show here that mainstream inference algorithms based on jointrees are a special case of the approach based on multi-linear functions, in a very precise sense. We use this result to prove new properties of jointree algorithms. We also discuss some practical and theoretical implications of this new finding.
The general theory of first-order spatio-temporal distortions of Gaussian pulses and beams

Ultrashort laser pulses are usually expressed in terms of the temporal and spectral dependences of their electric field. This approach disregards any couplings between the spatial coordinates and time and/or frequency. This assumption, however, often fails, as the generation and manipulation of ultrashort pulses require the introduction of spatio-temporal couplings. Furthermore, disregarding these couplings in ultrashort pulses also greatly limits the potential applications that could only be possible by exploiting the spatio-temporal behaviors. For these reasons, spatio-temporal couplings are receiving increased attention from researchers in recent years. Most of the work presented to date, however, focuses on a few particular couplings, lacking a general and rigorous analysis. We present a rigorous and mathematically elegant theory of first-order spatio-temporal distortions of Gaussian pulses and beams. We write pulses in four possible domains, xt, xω, kω, and kt, including the couplings. We identify couplings in intensity profiles as: pulse-front tilt, spatial dispersion, angular dispersion, and time vs. angle. We identify four new couplings that occur in phase: "wave-front rotation," "wave-front-tilt dispersion," "angular temporal chirp," and "angular frequency chirp." In addition, we provide normalized, dimensionless definitions for them, which range from -1 to 1. Finally, we show that for such parameters as pulse length, bandwidth, beam spot size and divergence angle, two separate definitions are required as "local" and "global" quantities, in presence of the couplings. Our approach completely determines the explicit relations between various spatio-temporal couplings in Gaussian pulses and beams. It can be generalized to arbitrary profiles by using computational analysis.
Accuracy of Mesh Based Cosmological Hydrocodes: Tests and Corrections

We perform a variety of tests to determine the numerical resolution of the cosmological TVD Eulerian code. Tests include 5123 and 2563 simulations of a Pk∝k−1 spectrum to check for self-similarity and a comparison of results with those from higher resolution smooth-particle hydrodynamics (SPH) codes and grid-based calculations. We conclude that in regions where density gradients are not produced by shocks, the code degrades resolution with a Gaussian smoothing (radius) length of 1.7 cells. At shock-caused gradients (for which the code was designed) the smoothing length is 1.1 cells. Finally, for β-model-fitted clusters, we can approximately correct the numerical resolution by the transformation R2core→R2core-(CΔl)2, where Δl is the cell size and C=1.1-1.7. When we use these corrections on our previously published computations for the standard cold dark matter (SCDM) and ΛCDM models, we find luminosity-weighted zero-redshift X-ray cluster core radii of 210 ± 86 h−1 and 280 ± 67 h−1 kpc, respectively, which are marginally consistent with observed values of 50-200 h−1 kpc. Using the corrected core radii, the COBE-normalized SCDM model predicts a number of bright (LX>1043 ergs s-1) clusters that is too high by a factor of ~20, and the ΛCDM model is consistent with observations.
Rated extremal principles for finite and infinite systems

In this article we introduce new notions of local extremality for finite and infinite systems of closed sets and establish the corresponding extremal principles for them, here called rated extremal principles. These developments are in the core geometric theory of variational analysis. We present their applications to calculus and optimality conditions for problems with infinitely many constraints.
Computers: from youth to manhood

You are very kind to honor me with the invitation to speak here today, and it is a pleasure to be here. I always appreciate a good excuse for leaving my overcoat and galoshes behind in Boston and coming out to sunny California. Furthermore, we are beginning to realize that although Boston is still of course the hub of the universe, nevertheless there are some pretty good ideas generated out here on the West Coast; and I hope I shall not return to New England without a few dozen of them in my carpet-bag.
Enantioselective addition of diethylzinc to aldehydes catalyzed by chiral titanate complexes with a tetradentate ligand

Abstract Enantioselective alkylation of aldehydes with Et 2 Zn has been studied. This catalytic system employs titanate complexes with a tetradentate helical ligand to facilitate the transformation.
The Long-Term Structure of Commodity Futures

Futures markets on agricultural commodities typically trade with maximum maturity dates of less than four years. If these markets did trade with maturities eight or ten years distant, futures prices would have value as price forecasts and as a way to structure long-term swaps and insurance contracts. Agricultural commodity markets generally exhibit mean reversion in spot prices and convenience yields. Spot markets also exhibit seasonality. This study develops and implements a procedure to generate long-term futures curves from existing futures prices. Data on lean hogs and soybeans are used to show that the method provides plausible results. Copyright 2012, Oxford University Press.
Obliquity variations of a moonless Earth

Abstract We numerically explore the obliquity (axial tilt) variations of a hypothetical moonless Earth. Previous work has shown that the Earth’s Moon stabilizes Earth’s obliquity such that it remains within a narrow range, between 22.1° and 24.5°. Without lunar influence, a frequency map analysis by Laskar et al. (Laskar, J., Joutel, F., Robutel, P. [1993]. Nature 361, 615–617) showed that the obliquity could vary between 0° and 85°. This has left an impression in the astrobiology community that a big moon is necessary to maintain a habitable climate on an Earth-like planet. Using a modified version of the orbital integrator mercury , we calculate the obliquity evolution for moonless Earths with various initial conditions for up to 4 Gyr. We find that while obliquity varies significantly more than that of the actual Earth over 100,000 year timescales, the obliquity remains within a constrained range, typically 20–25° in extent, for timescales of hundreds of millions of years. None of our Solar System integrations in which planetary orbits behave in a typical manner show obliquity accessing more than 65% of the full range allowed by frequency-map analysis. The obliquities of moonless Earths that rotate in the retrograde direction are more stable than those of prograde rotators. The total obliquity range explored for moonless Earths with rotation periods less than 12 h is much less than that for slower-rotating moonless Earths. A large moon thus does not seem to be needed to stabilize the obliquity of an Earth-like planet on timescales relevant to the development of advanced life.
Intermittency and Conditional Averaging in a Turbulent Nonpremixed Flame by Raman Scattering

Pulsed Raman scattering is used to determine zonal averages, intermittency, and conditional probability density functions (pdFs) for temperature, density, conserved scalar, and molecular composition in a turbulent, hydrogen jet diffusion flame. The conditional mean and rms values provide a data base for flame intermittency models. Both conventional and Favre-averaged turbulent zone pdf's of the conserved scalar are highly nonGaussian in the intermittent regions. Turbulent combustion models that assume a clipped Gaussian turbulent pdf in this region could give erroneous results for flame processes sensitive to pdf shapes such as NOX formation. Similar pdf shapes have been found in nonreacting wake flows and correlations obtained by Effelsberg and Peters using a three-zone (laminar, turbulent, and superlayer) model indicate that the superlayer can contribute up to 60°7o of the pdf.
ON A GROUPOID CONSTRUCTION FOR ACTIONS OF CERTAIN INVERSE SEMIGROUPS

We consider a version of the notion of F-inverse semigroup (studied in the algebraic theory of inverse semigroups). We point out that an action of such an inverse semigroup on a locally compact space has associated a natural groupoid construction, very similar to the one of a transformation group. We discuss examples related to Toeplitz algebras on subsemigroups of discrete groups, to Cuntz-Krieger algebras, and to crossed-products by partial automorphisms in the sense of Exel.
Workload and the nurse faculty shortage: Implications for policy and research

Although it is hypothesized that workload is a causative factor of the nurse faculty shortage and that nurse faculty workload is not equitable with that of faculty from other academic disciplines, it is not known whether evidence supports this assertion. This paper has three objectives: (1) to identify what is known about nurse faculty workload and its relationship to the nurse faculty shortage, (2) to determine whether evidence supports the assertion that nurse faculty workload is not equitable with faculty workload in other disciplines, and (3) to discuss policy and research implications for addressing workload and the nurse faculty shortage. Science Direct, medline, CINAHL, HealthSTAR databases, and the web were searched using combinations of nurse faculty, workload, academia, and equity. Findings suggest that the majority of research on nurse faculty workload has been limited to a single institution or region. Further, the literature lacks a comparison of nurse faculty workload with that of faculty from other disciplines. A study comparing workload across disciplines would shed light on the workload inequity hypothesis. More importantly, a systematic analysis of nurse faculty workload would facilitate the prioritization of strategies to address the shortage.
Foreign debt and economic growth

This paper empirically examines the relationship between government foreign debt and the growth rate of per capita GDP based on a total sample of 77 countries, as well as sub-samples of various regions. Cross-sectional estimates of the coefficient of foreign debt based on the total sample have a negative sign, but are not always statistically significant. Available data from African countries indicate that foreign debt and the growth rate of per capita GDP were negatively related at a high level of significance. For industrialized and Latin American sub-samples, this relationship is negative but statistically insignificant. The sub-sample Asian and other developing countries show a positive but insignificant relationship. JEL classification: F34, H6, O23.
Alternating direction adaptive grid generation

An alternating direction method has been developed to adaptively resolve numerical solutions to physical problems by moving the points of a coordinate grid. With the solution or with the salient quantities derived from it, a surface grid is defined over the grid on the physical region. Grid movement is computed on this abstractly defined solution surface with the use of pointwise weights and is then projected back to determine new locations in the physical region. The weights cause clustering relative to the uniform conditions of surface arc length and are formed with magnitudes of quantities that are used for point attraction. When the salient quantities have been used to form the surface, the gradients are implicitly revolved and surface curvature becomes the primary remaining quantity. In each coordinate direction, the magnitude of normal curvature is used; With arbitrary weights, a movement cycle generally consists of a sweep through the coordinate curves in a given direction on a curve-by-curve basis and then in alternating directions to do the same thing until all directions have been covered.
An assessment of spectral nonoscillatory schemes

A new spectral nonoscillatory interpolation scheme is proposed that achieves spectral accuracy in smooth regions and is nonoscillatory on piecewise discontinuous data. The essential idea behind the scheme is to increase the order of an ENO scheme in proportion to the number of points, wherever possible. Numerical experiments with the new scheme on interpolation, 1 D advection, inviscid Burgers' equation, and 1 D gas dynamics confirm the high resolution features of the scheme. Comparisons with the results of earlier spectral nonoscillatory schemes show that the new scheme is competitive both in efficiency and accuracy.
Synthetic Approaches to the Neuraminidase Inhibitors Zanamivir (Relenza) and Oseltamivir Phosphate (Tamiflu) for the Treatment of Influenza

Influenza, a severe viral infection of the respiratory system, is responsible for a significant morbidity and mortality due to both annual epidemics and unpredictable pandemics. In the United States alone, 10-20% of the population is affected every year, which results in approximately 110,000 hospitalizations and more than 20,000 deaths with an estimated cost of U.S. $12 billion.1 In addition to the annual occurrence of the disease, there is a growing concern that a worldwide pandemic will inevitably happen within the next few years. Since the 1500s, the world has seen 22 influenza pandemics, * Phone number: 1-(860)-6869021. Fax number: 1-(860)-7154978. E-mail address: Javier.Magano@Pfizer.com. Chem. Rev. XXXX, xxx, 000–000 A
Sloshing in microgravity

Abstract The International Space Station provides a low gravity environment for experiments that require very low acceleration. The steady component of acceleration due to the gravity gradient is in the microgravity range. It is possible to achieve microgravity levels for the variable component by using isolation racks. For experiments cooled by liquid cryogens sloshing may increase the variable acceleration at the experiment beyond acceptable levels. Sloshing of cryogens in microgravity can be predicted using a surface wave model. The model should include: a calculation of the shape of the unperturbed liquid–gas interface; a listing of the normal modes and resonant frequencies for the container; a prediction of the amplitude of the modes in response to the motion of the container; and a test to detect the breakdown of linear theory. A model is presented that contains these components. The shape of the interface is calculated and it is found that for most anticipated applications the interface is nearly cylindrical or spherical. Since gravity is not aligned with the symmetry of the container, the depth of the liquid is variable. Examples are presented to show how to estimate the extent of variable depth and curved interface on the normal modes and resonant frequencies. Equations are derived for the dynamic interaction of the isolation rack, the dewar and the sloshing motion. Damping is introduced by using boundary layer theory. Random vibration theory is applied to the incoherent component of the driving spectrum while standard resonance formalism is used for the coherent component. The model cannot be used if the wave amplitude becomes so large that linear theory does not apply. A procedure is developed to check for nonlinear difficulties.
Can impurity effects help to identify the symmetry of the order parameter of the cuprates

Abstract The effects of non-magnetic impurities on the properties of superconductors with order parameters (OP) of different symmetry are discussed. In particular, we contrast the case of a d x 2 − y 2 with various forms of an anisotropic s-wave (ASW) gap. The biggest qualitative difference occurs if the phase of the s-wave OP does not change sign.
Spatiotemporal dynamics of multimode optical solitons

As optical fiber communications and fiber lasers approach fundamental limits there is considerable interest in multimode fibers. In nonlinear science, they represent an exciting environment for complex nonlinear waves. As in single-mode fiber, solitons may be particularly important. Multimode solitons consist of synchronized, non-dispersive pulses in multiple spatial modes, which interact via the Kerr nonlinearity of the fiber. They are expected to exhibit novel spatiotemporal characteristics, dynamics and, like single-mode solitons, may provide a convenient intuitive tool for understanding more complex nonlinear phenomena in multimode fibers. Here we explore experimentally and numerically basic properties and spatiotemporal behaviors of these solitons: their formation, fission, and Raman dynamics.
Band invariants for perturbations of the harmonic oscillator

Abstract We study the direct and inverse spectral problems for semiclassical operators of the form S = S 0 + ℏ 2 V , where S 0 = 1 2 ( − ℏ 2 Δ R n + | x | 2 ) is the harmonic oscillator and V : R n → R is a tempered smooth function. We show that the spectrum of S forms eigenvalue clusters as ℏ tends to zero, and compute the first two associated “band invariants”. We derive several inverse spectral results for V, under various assumptions. In particular we prove that, in two dimensions, generic analytic potentials that are even with respect to each variable are spectrally determined (up to a rotation).
Baryon Oscillations and Consistency Tests for Photometrically Determined Redshifts of Very Faint Galaxies

We investigate the impact of uncertainties in the photometric redshift error probability distribution on dark energy constraints from detection of baryon acoustic oscillations in galaxy power spectra. We also consider the prospects for determining the photometric redshift error probability distribution from the galaxy power spectra themselves. We find that although a sufficiently precise determination of redshift biases δz and variances σ is not possible, a strong consistency test is. For example, if σz is known to 1%, then any redshift bias δz greater than 0.008 will be detectable in the proposed survey of the Large Synoptic Survey Telescope through baryon oscillations. We speculate about the utility of this test for interpretation of cosmic shear data.
Temperature Regulation and Metabolism in Mexican Freetail Bats

Body temperatures of Tadarida mexicana in their natural cave environment were usually maintained at high levels, even when ambient temperatures were low. Oxygen consumption rates were correspondingly higher in low environmental temperatures. However, in laboratory tests, body temperatures and metabolic rates are fairly dependent on ambient temperature.
Thermoelectric properties and microstructure of Ba8Al14Si31 and EuBa7Al13Si33

Powder samples of the type I clathrate phases, with the proposed stoichiometry Ba8Al16Si30 and Eu2Ba6Al16Si30, were synthesized using direct reaction of stoichiometric amounts of the elements. Rietveld refinement of powder X-ray diffraction data is consistent with the clathrate type I structure. Composition, microstructure, and thermoelectric property measurements were made on hot-pressed pellets. Stoichiometry of the Ba8Al16Si30 sample was determined from microprobe data to be Ba8Al14Si31, close to the deficient framework solid solution of the general formula, Ba8AlxSi42-3/4x[]4-1/4x (x = 14; [], open square indicates lattice defect). In the case of the rare-earth-substituted compound, microprobe analysis of the microstructure indicates that it is not single phase, but contains multiple components, most of the general clathrate stoichiometry. The majority phase has the stoichiometry EuBa7Al13Si32. Both phases show conductivity typical of heavily doped semiconductors with negative Seebeck coefficients. Th...
Optical Constraints on an X-ray Transient Source in M31

We have detected a transient X-ray source in the M31 bulge through a continuing monitoring campaign with the Chandra ACIS-I camera. The source was detected at R.A. = 00h42m33428 ± 011, decl. = +41°17'0337 ± 011 in only a single observation taken 2004 May 23. Fortuitous optical HST ACS imaging of the transient location prior to the X-ray outburst, along with follow-up HST ACS imaging during and after the outburst, reveals no transient optical source brighter than B(equivalent) = 25.5. The location of the source and its X-ray properties suggest that it is a low-mass X-ray binary (LMXB). Assuming the transient is similar to many Galactic X-ray novae, the X-ray luminosity of (3.9 ± 0.4) × 1037 ergs s-1 and the upper limit on the optical luminosity provide a prediction of ≤1.6 days for the orbital period of the binary system.