cssi/SciSciGPT-SciSciNet huggingface dataset:
Interchange Reconnection Alfvén Wave Generation

Given recent observational results of interchange reconnection processes in the solar corona and the theoretical development of the S-Web model for the slow solar wind, we extend the analysis of the 3D MHD simulation of interchange reconnection by Edmondson et al. (Astrophys. J. 707, 1427, 2009). Specifically, we analyze the consequences of the dynamic streamer-belt jump that corresponds to flux opening by interchange reconnection. Information about the magnetic field restructuring by interchange reconnection is carried throughout the system by Alfven waves propagating away from the reconnection region, distributing the shear and twist imparted by the driving flows, including shedding the injected stress-energy and accumulated magnetic helicity along newly open fieldlines. We quantify the properties of the reconnection-generated wave activity in the simulation. There is a localized high-frequency component associated with the current sheet/reconnection site and an extended low-frequency component associated with the large-scale torsional Alfven wave generated from the interchange reconnection field restructuring. The characteristic wavelengths of the torsional Alfven wave reflect the spatial size of the energized bipolar flux region. Lastly, we discuss avenues of future research by modeling these interchange reconnection-driven waves and investigating their observational signatures.
Predicting Arrival Delays: An Application of Spatial Analysis

Analysts have many tools available to forecast delays. However, spatial analysis does not readily come to mind when predicting delays. Based on the case study of Newark Liberty International Airport, this study illustrates the potential applications of prevalent geostatistical techniques to delay forecast. There is a high degree of dependence among delays in a space or neighborhood defined by hour of operation and by day. Local spatial autocorrelation statistics help determine how delays are autocorrelated to other ones in a space. Among the other spatial analytical techniques, kriging enables the interpolation of delay estimates at unobserved spaces based on the values at observed spaces. Error estimates can be mapped to define spatial patterns (spaces where delays are likely to be more intense). Finally, spatial error regression provides a method for analysts to test the reliability of their findings when spatial dependency in errors is not taken into account. The study shows that delays in taxi operations at Newark Liberty International Airport, the volume of arrivals at Newark Liberty International Airport, as well as arrival demand at Newark Liberty International Airport and John F. Kennedy International Airport have a significant impact on the total minutes of arrival delays at Newark Liberty International Airport. This suggests that delay-reduction initiatives need to focus ondemandmanagement atNewarkLiberty InternationalAirport andLaGuardiaAirport as well as on procedures to reduce taxi delays.
Opportunity costs and non‐scale free capabilities: profit maximization, corporate scope, and profit margins

The resource-based view on firm diversification, subsequent to Penrose (1959), has focused primarily on the fungibility of resources across domains. We make a clear analytical distinction between scale free capabilities and those that are subject to opportunity costs and must be allocated to one use or another, thereby shifting the discourse back to Penrose's (1959) original argument regarding the stock of organizational capabilities. The existence of resources and capabilities that must be allocated across alternative uses implies that profit-maximizing diversification decisions should be based upon the opportunity cost of their use in one domain or another. This opportunity cost logic provides a rational explanation for the divergence between total profits and profit margins. Firms make profit-maximizing decisions to increase total profit via diversification when the industries in which they are currently competing become relatively mature. Due to the spreading of these capabilities across more segments, we may observe that firms' profit-maximizing diversification actions lead to total profit growth but lower average returns. The model provides an alternative explanation for empirical observations regarding the diversification discount. The self-selection effect noted in recent work in corporate finance may not be indicative of inferior capabilities of diversifying firms but of the limited opportunity contexts in which these firms are operating. Copyright © 2010 John Wiley & Sons, Ltd.
Fault tolerance versus performance metrics for robot systems

Abstract The incorporation of fault tolerance techniques into robot systems improves the reliability, but also increases the hardware and computational requirements in the overall system. It is not always clear how to evaluate the merit, or ‘effectiveness’ of different fault tolerance approaches for a given application. In this paper, we present a new set of performance criteria designed to measure and compare the effectiveness of robot fault tolerance strategies. The measures, which are designed to evaluate fault tolerance/performance/cost tradeoffs, can also be used to evaluate pure performance or pure fault tolerance strategies. We show their usefulness using a variety of proposed fault tolerance approaches in the literature, focusing on multiprocessor control architectures.
Strategic Analysis of Securities Litigation against Independent Auditors

It has been claimed that the accounting profession faces a serious litigation crisis, largely attributable to frivolous class‐action lawsuits that allege securities fraud. In response to recent calls for research on accounting litigation, this paper develops and analyses a game‐theoretic model of securities class‐action litigation and settlement under present institutional arrangements in the United States. Two research questions are examined. First, what factors explain the outcomes of securities lawsuits against independent auditors in the U.S.? Second, what (if any) strategies exist that accounting firms might employ to deter unwarranted securities litigation, coerced settlements, and other objectionable outcomes? Our results indicate that (1) settlements are the predominant outcome of the securities litigation game because both sides generally receive higher expected payoffs from settlements than from trials; (2) the prevalence of protracted pre‐trial litigation in securities lawsuits is primarily att...
Vesta: Spin Pole, Size, and Shape from HST Images

Abstract HST images obtained over an interval of 71 hr at a scale of 52 km/pixel have been used to determine the spin pole, size, and shape of Vesta. Several bright and dark surface features allow control point stereogrammetric measurement of spin pole orientation. An independent solution of spin pole and shape can be made from the limb and terminator coordinates. A combined control point and limb solution for Vesta's rotation pole is at α 0 = 308° ± 10°, δ 0 = 48° ± 10°, J2000). Its shape can be fit by an ellipsoid of radii 280, 272, 227 (±12) km. The mean density of Vesta from the mass reported by Schubart and Matson (1979) is 3.8 ± 0.6 gm/cm 3 . For this density Vesta's shape is close to that of a Maclaurin spheroid with superposed variations of ∼15 km.
The microscopic response method: Theory of transport for systems with both topological and thermal disorder

In this paper, we review and substantially develop the recently proposed “Microscopic Response Method,” which has been devised to compute transport coefficients and especially associated temperature dependence in complex materials. The conductivity and Hall mobility of amorphous semiconductors (ASs) and semiconducting polymers are systematically derived, and shown to be more practical than the Kubo formalism. The effect of a quantized lattice (phonons) on transport coefficients is fully included and then integrated out, providing the primary temperature dependence for the transport coefficients. For higher-order processes, using a diagrammatic expansion, one can consistently include all important contributions to a given order and directly write out the expressions of transport coefficients for various processes.
SOUND VELOCITY vs. TEMPERATURE IN WATER-SATURATED SEDIMENTS

Sound velocity vs. temperature was measured in a continental shelf silt, a calcareous ooze, a deep‐sea red clay, a continental slope clay, and a quartz sand using a resonant chamber technique. The temperature effect on these water‐saturated sediments was approximately the same as for water alone; this similarity to water behavior would be expected inasmuch as the compressibility of a water‐sediment mixture is dominantly due to the relatively large water compressibility.
REACTIVE DESORPTION AND RADIATIVE ASSOCIATION AS POSSIBLE DRIVERS OF COMPLEX MOLECULE FORMATION IN THE COLD INTERSTELLAR MEDIUM

The recent discovery of terrestrial-type organic species such as methyl formate and dimethyl ether in the cold interstellar gas has proved that the formation of organic matter in the Galaxy begins at a much earlier stage of star formation than was previously thought. This discovery represents a challenge for astrochemical modelers. The abundances of these molecules cannot be explained by the previously developed ''warm-up'' scenario, in which organic molecules are formed via diffusive chemistry on surfaces of interstellar grains starting at 30 K, and then released to the gas at higher temperatures during later stages of star formation. In this article, we investigate an alternative scenario in which complex organic species are formed via a sequence of gas-phase reactions between precursor species formed on grain surfaces and then ejected into the gas via efficient reactive desorption, a process in which non-thermal desorption occurs as a result of conversion of the exothermicity of chemical reactions into the ejection of products from the surface. The proposed scenario leads to reasonable if somewhat mixed results at temperatures as low as 10 K and may be considered as a step toward the explanation of abundances of terrestrial-like organic species observed during the earliest stagesmore » of star formation.« less
The Stability and Efficiency of Economic and Social Networks

This paper studies the formation of networks among individuals. The focus is on the compatibility of overall societal welfare with individual incentives to form and sever links. The paper reviews and synthesizes some previous results on the subject, and also provides new results on the existence of pairwise-stable networks and the relationship between pairwise stable and efficient networks in a variety of contexts and under several definitions of efficiency.
On the order of eliminating dominated strategies

It is known that different orders of eliminating dominated strategies in n-person games may yield different reduced games. We give conditions which guarantee that the reduced game is unique. For finite games, the conditions include the well-known cases of strict dominance, and in a slightly weaker form, of regular dominance for zero sum and similar games.
EFFECT OF HELIUM SEDIMENTATION ON X-RAY MEASUREMENTS OF GALAXY CLUSTERS

The uniformity of the helium-to-hydrogen (He-to-H) abundance ratio in the X-ray emitting intracluster medium (ICM) is one of the commonly adopted assumptions in X-ray analyses of galaxy clusters and cosmological constraints derived from these measurements. In this paper, we investigate the effect of He sedimentation on X-ray measurements of galaxy clusters in order to assess this assumption and associated systematic uncertainties. By solving a set of flow equations for a H-He plasma, we show that the He-to-H mass ratio is significantly enhanced in the inner regions of clusters. The effect of He sedimentation, if not accounted for, introduces systematic biases in observable properties of clusters derived using X-ray observations. We show that these biases also introduce an apparent evolution in the observed gas mass fractions of X-ray luminous, dynamically relaxed clusters and hence biases in observational constraints on the dark energy equation of state parameter, w, derived from the cluster distance-redshift relation. The Hubble parameter derived from the combination of X-ray and Sunyaev-Zel'dovich effect measurements is affected by the He sedimentation process as well. Future measurements aiming to constrain w or H_0 to better than 10% may need to take into account the effect of He sedimentation. We propose that the evolution of gas mass fraction in the inner regions of clusters should provide unique observational diagnostics of the He sedimentation process.
Termination of programs represented as interpreted graphs

This work is concerned with the termination problem of interpreted graphs. An interpreted graph can be considered as an abstract model of algorithms; it consists of a directed graph, where:1. With each vertex v, there is associated a domain Dv, and2. With each arc a leading from vertex v to vertex v', there is associated a total test predicate Pa(Dv → {T, F}) and a total function fa (Dv* → Dv'), where Dv* = {x | x ∈ Dv ∧ Pa (x) = T}.
Kinetics of the release of poliomyelitis virus from single cells.

Abstract A technique is described which allows the handling and observation of single animal cells in microdrops. The kinetics of the release of poliomyelitis virus type 1 (Brunhilde strain) by individual monkey kidney cells was studied. After a latent period of a few hours, the bulk of the virus was released in less than 1 hour. Characteristic morphological changes appear to be correlated with the release of the virus.
Model bond albedos of extrasolar giant planets

Abstract The atmospheres of extrasolar giant planets are modeled with various effective temperatures and gravities, with and without clouds. Bond albedos are computed by calculating the ratio of the flux reflected by a planet (integrated over wavelength) to the total stellar flux incident on the planet. This quantity is useful for estimating the effective temperature and evolution of a planet. We find it is sensitive to the stellar type of the primary. For a 5 M Jup planet the Bond albedo varies from 0.4 to 0.3 to 0.6 as the primary star varies from A5V to G2V to M2V in spectral type. It is relatively insensitive to the effective temperature and gravity for cloud-free planets. Water clouds increase the reflectivity of the planet in the red, which increases the Bond albedo. The Bond albedo increases by an order of magnitude for a 13 M Jup planet with an M2V primary when water clouds are present. Silicate clouds, on the other hand, can either increase or decrease the Bond albedo, depending on whether there are many small grains (the former) or few large grains (the latter).
Oxy- and thio-phosphorus acid derivatives of tin(IV). The crystal and molecular structure of O-methylmethylphosphatotriphenyltin(IV)☆

Abstract O-Methylmethylphosphatotriphenyltin(IV) (II) is synthesized by treating stoichiometric amounts of O,O′-dimethylmonothiophosphatotriphenyltin(IV) (I) with mercury. The negative 119Sn chemical shift in solution relative to tetramethyltin for I corresponds to higher than four coordination (at tin) in solution. The values of the 119Sn Mossbauer isomer shift for I and II confirm the presence of tin as tin(IV). The magnitudes of the quadrupole splitting and the ratios of the QS to the IS of both compounds reveal that tin is higher than four coordinated. The solid state structure of II was determined by X-ray diffraction. The compound crystallized in the trigonal space group R 3 with a, b 31.433(15), c 10.259(3) A, V 8778.2 A3, Z = 18, Dx 1.56 g cm−3 at 138 K. In the solid state compound II exists as a highly symmetric cyclic hexamer in which planar trimethyltin(IV) groups are axially bridged by O-P-O linkages. The geometry about tin is trigonal bipyramidal with an axial O-Sn-O angle of 177.1(2)° and average C-Sn-C angle of 120.0(2)°. The structure of the hexameric ring is linear at tin but bent at phosphorus with an O-P-O angle of 117.1(2)°.
Building your own computer

Microcomputer kits have changed the build-it-yourself hobby dramatically. Until the introduction of such kits, only about two dozen amateur computers of any real complexity were in operation; nearly all were built by engineers in the computer industry. Formidable problems exist when trying to use or rebuild obsolete vacuum-tube or transistor computers, such as the non-availability of schematics. Building from scratch is so complex that usually only electronics engineers achieve it. Building a machine that uses the instruction set of a commercial computer is popular. Microprocessors were introduced only a few years ago, and already two dozen microcomputer kits are available, ranging from inexpensive minimal machines using assembly language, to high-level-language systems costing several thousand dollars.
Convenient synthesis of 1-alkyl-2, 5-bis(thiophenylmethylene)pyrroles using the Mannich reaction

Abstract Aminomethylation of 1-alkylpyrrole (alkyl: hydrogen, methyl, hexyl, dodecyl)by aqueous formaldehyde and dimethylamine hydrochloride, followed by reaction with iodomethane, affords the 1-alkyl-2,5-bis[(trimethylamino) methyl]pyrrole diiodide. These diiodide salt derivatives react with sodium thiophenoxide to give 1-alkyl-2,5-bis(thiophenyl methylene) pyrrole yielding monomers found to be useful for synthesizing new conducting polymers.
A note on error bounds for function approximation using nonlinear networks

For many problems in classification, compensation, adaptivity, identification, and signal processing, results concerning the representation and approximation of nonlinear functions can be of particular interest to engineers. Here we consider a large class of functionsf that map ℝ n into the set of real or complex numbers, and we give bounds on the number of parameters of a certain approximation network so thatf can be approximated to within a prescribed degree of accuracy using an appropriate configuration of the network. We also describe related work in the neural networks literature.
1H-Tetrazole as Catalyst in Phosphomorpholidate Coupling Reactions: Efficient Synthesis of GDP-Fucose, GDP-Mannose, and UDP-Galactose

An improved procedure is described for the efficient and high-yield (76−91%) synthesis of nucleoside diphosphate sugars from the readily available nucleoside 5‘-monophosphomorpholidate and sugar 1-phosphate in the presence of 1H-tetrazole. Comparative kinetic investigations by means of 31P NMR spectroscopy with different additives (1,2,4-triazole, acetic acid, N-hydroxysuccinimide, 4-(dimethylamino)pyridine hydrochloride, perchloric acid) and mass spectrometric analysis suggest that tetrazole acts as an acid and as a nucleophilic catalyst in the pyrophosphate bond formation.
Cooperative multi-robot estimation and control for radio source localization

We develop algorithms for estimation and control that allow a team of robots equipped with range sensors to localize an unknown target in a known but complex environment. We present an experimental model for radio-based time-of-flight range sensors. Adopting a Bayesian approach for estimation, we then develop a control law which maximizes the mutual information between the robot's measurements and their current belief of the target position. We describe experimental results for a robot team localizing a stationary target in several representative indoor environments in which the unknown target is reliably localized with an error well below the typical error for individual measurements.
Layered coding vs. multiple descriptions for video streaming over multiple paths

In this paper, we examine the performance of specific implementations of multiple description coding and of layered coding for video streaming over error-prone packet switched networks. We compare their performance using different transmission schemes with and without network path diversity. It is shown that, given specific implementations, there is a large variation in relative performance between multiple description coding and layered coding depending on the employed transmission scheme. For scenarios where the packet transmission schedules can be optimized in a rate-distortion sense, layered coding provides a better performance. The converse is true for scenarios where the packet schedules are not rate-distortion optimized.
Effect of Sampling Height on the Concentration of Airborne Fungal Spores

Background Spores of many fungal species have been documented as important aeroallergens. Airborne fungal spores are commonly collected from the outdoor air at the rooftop level of high buildings; however, human exposure usually occurs nearer to the ground. It is necessary to estimate the concentration of airborne fungal spores at the human breathing level to evaluate the actual human exposure to outdoor aeroallergens. Objective To compare the concentration of airborne fungal spores at human respiration level (1.5 m above the ground) and at roof level (12 m height). Methods Air samples were collected using 2 Burkard volumetric 7-day recording spore traps from July 1 to October 31, 2005. One sampler was located on the roof of a building at the University of Tulsa at 12 m above ground, and the second sampler was placed in the courtyard of the building at 1.5 m. Burkard slides were analyzed for fungal spores by light microscopy at a magnification of 1,000, and the results were statistically analyzed to compare the concentration of airborne fungal spores at the 2 levels. Results The ground sampler had significantly higher concentration of basidiospores, Penicillium/Aspergillus -type spores, and smut spores than the roof sampler. By contrast, the rooftop sampler registered significantly higher concentration of Alternaria , ascospores, and other spores. Conclusions Ground level had significantly higher concentration of some important fungal aeroallergens but lower concentrations of others, suggesting that sampling height is one of the many variables that influence bioaerosol levels.
Facile synthesis of N-Fmoc-serine-S-GlcNAc: a potential molecular probe for the functional study of O-GlcNAc

Abstract A methabolically stable β-N-acetylglucosaminyl-1-thio-N-Fmoc-serine (S-GlcNAc-Ser) derivative was synthesized in two procedures: one involving a coupling of a readily obtainable 1-pseudo-thiourea of GlcNAc (S-GlcNAc) and iodo-N-Boc- l -alanine benzyl ester, and the other utilizing a modified Mitsunobu reaction of GlcNAc-SH and a serine derivative.
Stille cross-couplings of unactivated secondary alkyl halides using monoorganotin reagents.

The first catalyst that achieves Stille cross-couplings of secondary (as well as primary) alkyl halides has been developed. The method employs easily handled and inexpensive catalyst components (NiCl2 and 2,2‘-bipyridine) and, through the use of monoorganotin reagents, avoids the formation of toxic and difficult-to-remove triorganotin side products.
The analytics of technology news shocks

Abstract This paper constructs several models in which, unlike the standard neoclassical growth model, positive news about future technology generates an increase in current consumption, hours and investment. These models are said to exhibit procyclical news shocks. We find that all models that exhibit procyclical news shocks in our paper have two commonalities. There are mechanisms to ensure that: (I) consumption does not crowd out investment, or vice versa; (II) the benefit of forgoing leisure in response to news shocks outweighs the cost. Among the models we consider, we believe, one model holds the greatest potential for explaining procyclical news shocks. Its critical assumption is that news of the future technology also illuminates the nature of this technology. This illumination in turn permits economic actors to invest in capital that is forward-compatible, i.e. adapted to the new technology. On the technical side, our paper reintroduces the Laplace transform as a tool for studying dynamic economies analytically. Using Laplace transforms we are able to study and prove results about the full dynamics of the model in response to news shocks.
TeV blazars - observations and models

Since the first TeV blazar Markarian (Mrk) 421 was detected in 1992, the number of established TeV gamma-ray emitting BL Lac objects has grown to 6, with redshifts ranging from 0 031 (Mrk 421) to 0.129 (H 1426+428). The intensive study of these sources has had a major impact on our understanding of the blazar phenomenon. The most notable observational results have been extremely fast large amplitude flux and spectral variability on hour time scales, and a pronounced X-ray - TeV gamma-ray flux correlation. In this paper, we discuss recent observational results and report on progress in their theoretical interpretation.
Frequency stability of a dual-mode whispering gallery mode optical reference cavity

We report an investigation of laser frequency stabilization using a whispering gallery mode resonator that is temperature stabilized by a dual-mode technique. This dual-mode technique has yielded mode volume temperature instabilities at the nK level, suggesting that high frequency stability may also be reached. Here, we experimentally and theoretically investigate the dynamics of such a system and the important factors affecting the achievable frequency stability. We calculate that the dual-mode technique can reduce the effective fractional temperature coefficient of the reference system to 3.6×10⁻⁸ K⁻¹ within the temperature feedback bandwidth. We demonstrate a 1560 nm laser stabilized to 1.3×10⁻¹² at 1 s and 1.1×10⁻¹⁰ at 1000 s, corresponding to a long-term drift of 21 kHz/hr.
Maglev Apparatus for Power Minimization and Control of Artificial Hearts

This project is directed at the third generation of heart pumps being developed in commercial research laboratories which employ feedback-controlled magnetically levitated pump impellers. Unique features of the control problem are the quasi-periodic pressure disturbances of the natural heart and nonlinearities of the magnetic levitation system. The main motivation for this paper is the power consumption due to quasi-periodic disturbance of natural heart. Since clinical studies are not possible for the vast majority of our work, there is a need for an apparatus to simulate the left ventricular assist device (LVAD) for controller design. Inspired by this need, we design a novel experimental apparatus to study the Maglev LAVDs. We develop a nonlinear model, then a linearized model followed by simulation and stabilization of the closed-loop system using a virtual zero power (VZP) controller.
Municipal Incorporation in the United States

This article empirically examines the formation of municipalities in the USA. It traces change in unincorporated areas over decades to determine how basic dimensions of population heterogeneity aff...
Computing Vergne polarizing subalgebras

According to the orbit method, the construction of a unitary irreducible representation of a nilpotent Lie group requires a precise computation of some polarizing subalgebra subordinated to a linear functional in the linear dual of the corresponding Lie algebra. This important step is generally challenging from a computational viewpoint. In this paper, we provide an algorithmic approach to the construction of the well-known Vergne polarizing subalgebras. The algorithms presented in this paper are specifically designed so that they can be implemented in computer algebra systems. We also show there are instances where Vergne’s construction could be refined for the sake of efficiency. Finally, we adapt our refined procedure to free nilpotent finite-dimensional Lie algebras of step-two to obtain simple and precise descriptions of Vergne polarizing algebras corresponding to all linear functionals in a dense open subset of the linear dual of the corresponding Lie algebra. Also, a program written for Mathematica...
Infrared Spectroscopy of Wide Composition Range xNa2S + (1 –x)B2S3 Glasses

Wide composition range studies of the IR spectra of xNa2S + (1 –x)B2S3 glasses are reported for the first time. Glasses can be prepared in two composition regions: 0 x 0.33 in a low-alkali region and 0.55 x 0.80 in a highalkali region. The structures of glasses in the former region are dominated by the creation of tetrahedral boron units similar to those observed in the alkali borate glasses. For pure B2S3, a large fraction of six-membered rings is found, as in glassy B2O3. As alkali is added, the vibrational frequency of the six-membered ring mode decreases, but not the intensity, and a new band grows in which is used to propose, by analogy with the alkali borate glasses, that the fraction of tetrahedral borons increases with alkali sulfide content. These observations suggest that isolated six-membered rings persist even in the presence of tetrahedral borons. For the high-alkali glasses, both the six-membered rings and tetrahedral boron structures are destroyed in preference to the formation of isolated orthothioborate groups, Na3BS3. The IR spectra of the high-alkali glasses show a monotonic increase in symmetry and simplicity, indicating an increase in structural simplicity as the orthothioborate composition is approached. For the orthothioborate composition, both glass and polycrystal can be prepared. The IR spectra of the two phases are very similar, with the glass exhibiting a broadened absorption envelope.
The Molecular Accretion Flow in G10.6–0.4

We have observed the ultracompact H II region G10.6-0.4 with the VLA in the 23 GHz continuum and the NH3 (3, 3) inversion line. By analyzing the optical depth of the line as well as the kinematics, we have detected a flattened, rotating molecular accretion flow. We detect the fact that the highest column density gas is more flattened, that is, distributed more narrowly, than the lower column density gas, and that there is some inclination of the rotation axis. The rotation is sub-Keplerian, and the molecular gas is not in a rotationally supported disk. We do not find a single massive (proto-)star forming in a scaled-up version of low-mass star formation. Instead, our observations suggest a different mode of clustered massive star formation, in which the accretion flow flattens but does not form an accretion disk. Moreover, in this mode of star formation the central object can be a group of massive stars rather than a single massive star.
Tentative Detection of the Cosmic Infrared Background at 2.2 and 3.5 Microns Using Ground-based and Space-based Observations

The cosmic infrared background (CIRB) is the sum total of the redshifted and reprocessed short-wavelength radiation from the era of galaxy formation, and hence contains vital information about the history of galactic evolution. One of the main problems associated with estimating an isotropic CIRB in the near-infrared (1-5 μm) is the unknown contribution from stars within our own Galaxy. The optimal observational window to search for a background in the near-IR is at 3.5 μm since that is the wavelength region where the other main foreground, the zodiacal dust emission, is the least. It is not possible to map out the entire 3.5 μm sky at a resolution that will accurately estimate the flux from stars. However, since the CIRB is presumably isotropic, it can potentially be detected by selecting a smaller field and imaging it at good resolution to estimate the stellar intensity. We selected a 2° × 2° "dark spot" near the north Galactic pole which had the least intensity at 3.5 μm after a zodiacal light model was subtracted from the all-sky maps generated by the Diffuse Infrared Background Experiment (DIRBE). Still, the large area of the field made it very difficult to mosaic at 3.5 μm using the available arrays. Thus, the field was mosaicked at 2.2 μm, then the bright stars were selected and reimaged at 2.2 and 3.5 μm. The resulting total intensity of the bright stars was combined with a model for the contribution from dimmer stars and subtracted from the zodi-subtracted DIRBE map. The contribution from the interstellar medium was also subtracted, leaving a residual intensity at 2.2 μm of 16.4 ± 4.4 kJy sr-1 or 22.4 ± 6.0 nW m-2 sr-1, and at 3.5 μm of 12.8 ± 3.8 kJy sr-1 or 11.0 ± 3.3 nW m-2 sr-1. The nature of our analysis suggests that this excess emission is probably a detection of the cosmic background in the near-infrared.
Surface temperature distribution along a thin liquid layer due to thermocapillary convection

The surface temperature distributions due to thermocapillary convections in a thin liquid layer with heat fluxes imposed on the free surface were investigated. The nondimensional analysis predicts that, when convection is important, the characteristics length scale in the flow direction L, and the characteristic temperature difference delta T sub o can be represented by L and delta T sub o approx. (A2Ma)/1/4 delta T sub R, respectively, where L sub R and delta sub R are the reference scales used in the conduction dominant situations with A denoting the aspect ratio and Ma the Marangoni number. Having L and delta sub o defined, the global surface temperature gradient delta sub o/L, the global thermocapillary driving force, and other interesting features can be determined. Numerical calculations involving a Gaussian heat flux distribution are presented to justify these two relations.
Internal Audit Assistance and External Audit Timeliness

SUMMARY: Professional standards guide external auditors to consider the effect of the client's internal audit work and opportunities to utilize the direct assistance of the internal audit function when planning and conducting audits. We examine the effect of internal audit assistance on external audit timeliness via the extent of external audit delay. We hypothesize and find that internal audit assistance is negatively associated with external audit delay. We also document moderating relationships between internal audit assistance and other internal audit environment characteristics, such as the extent of internal control reliance, coordination with the external auditor, and the investment in internal audit quality. Overall, our findings have implications for firms and external auditors who are evaluating the role and use of internal audit functions. Namely, our findings suggest that internal audit assistance may not only result in audit cost savings, but also in greater audit efficiencies. These finding...
Oxo and imido ligands in late transition metal chemistry

Our results on the chemistry of second and third series late transition metal oxo (O2−) and imido (RN2−) complexes are presented from a semi-historical perspective. Synthetic results are discussed followed by reaction chemistry and properties of the complexes.
Bilinear and quadratic variants on the Littlewood-Offord problem

If f(x 1, …, x n ) is a polynomial dependent on a large number of independent Bernoulli random variables, what can be said about the maximum concentration of f on any single value? For linear polynomials, this reduces to one version of the classical Littlewood-Offord problem: Given nonzero constants a 1, …,a n , what is the maximum number of sums of the form ±a 1 ± a 2 ± … ± a n which take on any single value? Here we consider the case where f is either a bilinear form or a quadratic form. For the bilinear case, we show that the only forms having concentration significantly larger than n −1 are those which are in a certain sense very close to being degenerate. For the quadratic case, we show that no form having many nonzero coefficients has concentration significantly larger than n −1/2. In both cases the results are nearly tight.
Dynamic recovery in silicate-apatite structures under irradiation and implications for long-term immobilization of actinides

The irradiation responses of Ca2La8(SiO4)6O2 and Sr2Nd8(SiO4)6O2 with the apatite structure are investigated to predict their long-term behaviour as host phases for immobilization of actinide elements from the nuclear fuel cycle. Different ions and energies are used to study the effects of dose, temperature, atomic displacement rate and ionization rate on irradiation-induced amorphization and recrystallization. The dose for amorphization increases with temperature in two stages, below and above 150 K. In the high temperature stage relevant to actinide immobilization, the increase of amorphization dose with temperature exhibits a strong dependence on the ratio of ionization rate to displacement rate for the different ions. Data analysis using a dynamic model for amorphization reveals that ionization-induced processes, with activation energy of 0.15 ± 0.02 eV, dominate dynamic recovery for ions from Ne through Xe. For heavier Au ions or for alpha-recoil nuclei emitted in alpha decay of actinides, ionization becomes less dominant and dynamic recovery is controlled primarily by thermally-driven processes. In post-irradiation annealing studies of amorphous samples, epitaxial thermal recrystallization is observed at 1123 K, and irradiation-enhanced nucleation of nanocrystallites is observed under irradiation with heavier ions. The recrystallization temperature under irradiation decreases with increasing ion mass to a value of ∼823 K, which also defines the thermally-driven critical temperature for amorphization under irradiation with heavy ions. Some partial recovery due to alpha particle irradiation at 300 K is observed that suggests a self-healing mechanism in apatite phases containing actinides. Based on the results and dynamic model, the temperature and time dependences of amorphization in silicate-apatite host phases for actinide immobilization are predicted.
AIDS and Antiretroviral Drugs in South Africa: Public Health, Politics, and Individual Suffering: A Review of Brian Tilley's It's My Life

The word "epidemic" seems inadequate to describe the spread of the HIV virus in sub-Saharan Africa. The latest estimates suggest that 28.5 million people in this region are infected including 5 million in South Africa alone. The HIV and AIDS pandemic with infection rates of over 20 percent in seven African countries rivals the worst of historys disease outbreaks including the bubonic plague of medieval times. The devastating effects of the disease on the continent are compounded by extreme poverty in the region and the lack of medical infrastructure essential for delivering the full range of available treatments for HIV infection AIDS and the opportunistic infections associated with the disease. Of the 40 million people infected with HIV worldwide only 730000 receive combination antiretroviral therapies. In the entire African continent only 30000 infected people currently receive such forms of treatment. Brian Tilleys documentary film Its My Life tells the story of AIDS activist Zackie Achmats decision to forego antiretroviral medications to treat his HIV infection in protest against the South African governments refusal to provide these drugs in public hospitals and AIDS clinics. Achmat a 38-year-old founding member and director of the Treatment Action Campaign (TAC) hopes that his actions will persuade the South African government to implement a treatment plan for all of the "faceless" South Africans living with HIV. The antiretroviral cocktail of drugs can cost between $10000 and $15000 per year in the United State -- a price well beyond the means of most South Africans or their government. (excerpt)
Centrality-constrained graph embedding

Visual rendering of graphs is a key task in the mapping of complex network data. Although most graph drawing algorithms emphasize aesthetic appeal, certain applications such as travel-time maps place more importance on visualization of structural network properties. The present paper advocates a graph embedding approach with centrality considerations to comply with node hierarchy. The problem is formulated as one of constrained multi-dimensional scaling (MDS), and it is solved via block coordinate descent iterations with successive approximations and guaranteed convergence to a KKT point. In addition, a regularization term enforcing graph smoothness is incorporated with the goal of reducing edge crossings. Experimental results demonstrate that the algorithm converges, and can be used to efficiently embed large graphs on the order of thousands of nodes.
Mortar: filling the gaps in data center memory

Data center servers are typically overprovisioned, leaving spare memory and CPU capacity idle to handle unpredictable workload bursts by the virtual machines running on them. While this allows for fast hotspot mitigation, it is also wasteful. Unfortunately, making use of spare capacity without impacting active applications is particularly difficult for memory since it typically must be allocated in coarse chunks over long timescales. In this work we propose re- purposing the poorly utilized memory in a data center to store a volatile data store that is managed by the hypervisor. We present two uses for our Mortar framework: as a cache for prefetching disk blocks, and as an application-level distributed cache that follows the memcached protocol. Both prototypes use the framework to ask the hypervisor to store useful, but recoverable data within its free memory pool. This allows the hypervisor to control eviction policies and prioritize access to the cache. We demonstrate the benefits of our prototypes using realistic web applications and disk benchmarks, as well as memory traces gathered from live servers in our university's IT department. By expanding and contracting the data store size based on the free memory available, Mortar improves average response time of a web application by up to 35% compared to a fixed size memcached deployment, and improves overall video streaming performance by 45% through prefetching.
Theory of high-energy emission from the pulsar/Be star system PSR 1259-63. I. Radiation mechanisms and interaction geometry

We study the physical processes in the system containing the 47 ms radio pulsar PSR B1259{minus}63 orbiting around a Be star in a highly eccentric orbit. This system is the only known binary where a radio pulsar is observed to interact with gaseous material from a Be star. A rapidly rotating radio pulsar such as PSR B1259{minus}63 is expected to produce a wind of electromagnetic emission and relativistic particles, and this binary is an ideal astrophysical laboratory to study the mass outflow/pulsar interaction in a highly time-variable environment. Motivated by the results of a recent multiwavelength campaign during the 1994 January periastron passage of PSR B1259{minus}63, we discuss several issues regarding the mechanism of high-energy emission. Unpulsed power-law emission from the PSR B1259{minus}63 system was detected near periastron in the energy range 1{endash}200 keV. The observed X-ray/soft {gamma}-ray emission is characterized by moderate luminosity, small and constant column density, lack of detectable pulsations, and peculiar spectral and intensity variability. In principle, high-energy (X-ray and gamma-ray) emission from the system can be produced by different mechanisms including (1) mass accretion onto the surface of the neutron star, (2) {open_quotes}propeller{close_quotes}-like magnetospheric interaction at a small pulsar distance, and (3) shock-powered emission inmore » a pulsar wind termination shock at a large distance from the pulsar. We carry out a series of calculations aimed at modeling the high-energy data of the PSR B1259{minus}63 system throughout its orbit and especially near periastron. We find that the observed high-energy emission from the PSR B1259{minus}63 system is not compatible with accretion or propeller-powered emission. This conclusion is supported by a model based on standard properties of Be stars and for plausible assumptions about the pulsar/outflow interaction geometry. (Abstract Truncated)« less
Dynamical friction and resonance trapping in planetary systems

A restricted planar circular three-body system, consisting of the Sun and two planets, is studied as a simple model for a planetary system. The mass of the inner planet is considered to be larger, and the system is assumed to be moving in a uniform interplanetary medium with constant density. Numerical integrations of this system indicate a resonance capture when the dynamical friction of the interplanetary medium is taken into account. As a result of this resonance trapping, the ratio of orbital periods of the two planets becomes nearly commensurable, and the eccentricity and semimajor axis of the orbit of the outer planet, and also its angular momentum and total energy, become constant. It appears from the numerical work that the resulting commensurability and also the resonant values of the orbital elements of the outer planet are essentially independent of the initial relative positions of the two bodies. The results of numerical integrations of this system are presented, and the first-order partially averaged equations are studied in order to elucidate the behaviour of the system while captured in resonance.
NOVEL PHOTOCHEMICAL HYDROLYSIS OF O-ACETYLPHENYLACETONITRILES TO AMIDES

Irradiation of o-acetylphenylacetonitriles 1a,b in methanol (λ >280 nm) leads to essentially quantitative photohydrolysis with formation of the corresponding ketal amides 3a,b. The mechanism proposed for this novel reaction is supported by the qualitatively different photochemical behavior of 1c and by a labeling experiment with 1a-L that confirms transfer of the carbonyl oxygen atom of 1a to the amide oxygen atom of 3a.
The evolution of virtual machine architecture

In the early 1960's two major evolutionary steps were taken with regard to computing systems architecture. These were the emergence of I/O processors and the use of multiprogramming to improve resource utilization and overall performance. As a consequence of the first step computing systems became multiprocessor configurations where nonidentical processors could have access to the common main memory of the system. The second step resulted in several computational processes sharing a single processor on a time-multiplexed basis while vying for a common pool of resources.
Uncertainty-driven view planning for underwater inspection

We discuss the problem of inspecting an underwater structure, such as a submerged ship hull, with an autonomous underwater vehicle (AUV). In such scenarios, the goal is to construct an accurate 3D model of the structure and to detect any anomalies (e.g., foreign objects or deformations). We propose a method for constructing 3D meshes from sonar-derived point clouds that provides watertight surfaces, and we introduce uncertainty modeling through non-parametric Bayesian regression. Uncertainty modeling provides novel cost functions for planning the path of the AUV to minimize a metric of inspection performance. We draw connections between the resulting cost functions and submodular optimization, which provides insight into the formal properties of active perception problems. In addition, we present experimental trials that utilize profiling sonar data from ship hull inspection.
The Kesten-Stigum Reconstruction Bound Is Tight for Roughly Symmetric Binary Channels

We establish the exact threshold for the reconstruction problem for a binary asymmetric channel on the b-ary tree, provided that the asymmetry is sufficiently small. This is the first exact reconstruction threshold obtained in roughly a decade. We discuss the implications of our result for Glauber dynamics, phylogenetic reconstruction, noisy communication and the so-called "replica symmetry breaking" in spin glasses and random satisfiability problems.
Formation, motion and high-temperature superconductivity of large bipolarons

Abstract Unlike small (localized) bipolarons, large (mobile) bipolarons can yield bipolaronic superconductivity. The stringent conditions for the formation of large bipolarons as well as distinctive features of the normal-state transport and superconducting-state properties of large bipolarons appear consistent with observations of the high-temperature superconductors.