cssi/SciSciGPT-SciSciNet huggingface dataset:
HETEROSKEDASTICITY-ROBUST INFERENCE IN FINITE SAMPLES

Abstract Since the advent of heteroskedasticity-robust standard errors, several papers have proposed adjustments to the original White formulation. We replicate earlier findings that each of these adjusted estimators performs quite poorly in finite samples. We propose a class of alternative heteroskedasticity-robust tests of linear hypotheses based on an Edgeworth expansion of the test statistic distribution. Our preferred test outperforms existing methods in both size and power for low, moderate, and severe levels of heteroskedasticity.
A NEW LOOK AT OPEN CLUSTER NGC 6520

We use CCD and photoelectric photometry with Stromgren filters along with medium resolution spectra to investigate NGC 6520, an open cluster very nearly in the direction of the galactic center. We find an age of 60 Myr, a distance of 2 kpc, and an average reddening E( b - y) = 0.295, which increases toward the south. The average heliocentric radial velocity of the B stars is - 29 km s(-1), while the velocity of the nearby Barnard 86 is about 0 ( heliocentric; - 11 km s(- 1) compared to the LSR). This velocity difference amounts to about 1.8 kpc since the cluster formed, implying that it is extremely doubtful NGC 6520 is related to Barnard 86.
Survival of Planetary Systems

Gravitational interactions (i.e., disk tides) between a newly formed protoplanet and its precursor disk give rise to a net torque that drains angular momentum from the protoplanet's orbit. As a result, protoplanetary objects suffer orbital decay as the disk attempts to destroy the very system it spawns. Survival of a planetary system may be a rather uncertain outcome, and the fraction of circumstellar disks that produce an extant system could be significantly less than unity. Newly discovered close stellar companions may be circumstantial evidence of such large-scale orbit migrations. A scheme for in situ accretion of such objects is outlined that is consonant with a strong tidal influence.
Asymmetric total synthesis of dendrobatid alkaloid 251F.

The dendrobatid alkaloid (−)-251F was synthesized. The key steps of the synthesis were (1) an asymmetric Diels−Alder reaction to establish four of the necessary stereocenters in the target, (2) a ring-opening/ring-closing metathesis reaction to establish a key [3.3.0] bicyclic intermediate, and (3) an intramolecular Schmidt reaction.
Period locking due to delayed feedback in a laser with saturable absorber

The pulsating output of a laser with a saturable absorber subject to delayed optical feedback locks to an integer fraction of delay time. Equations for the period of the laser predict the occurrence of the different locking states as well as the value of the pump when there is a switch between the locked states.
The risk of risk assessment

Appropriate risk management can only be based on sound risk assessment. The sources of uncertainty involved in risk assessment are discussed and a number of approaches to improving such assessments are recommended.
Cuspidal systems for affine Khovanov–Lauda–Rouquier algebras

A cuspidal system for an affine Khovanov–Lauda–Rouquier algebra \(R_\alpha \) yields a theory of standard modules. This allows us to classify the irreducible modules over \(R_\alpha \) up to the so-called imaginary modules. We describe minuscule imaginary modules, laying the groundwork for future study of imaginary Schur–Weyl duality. We introduce colored imaginary tensor spaces and reduce a classification of imaginary modules to one color. We study the characters of cuspidal modules. We show that under the Khovanov–Lauda–Rouquier categorification, cuspidal modules correspond to dual root vectors.
Estimation of Fractional Dependent Variables in Dynamic Panel Data Models With an Application to Firm Dividend Policy

Fractional dependent variables and models with state dependence arise in many economic applications; however, estimating models with fractional dependent variables is complicated by the presence of two corner solution outcomes. When coupled with a dynamic panel data setting, estimating quantities of interest can be quite complex or computationally difficult. This article demonstrates a method for estimating fractional response variables, which is easy to implement, and presents an application of the technique to the determination of firm dividend policy. The estimation demonstrates that neglecting dynamics, unobserved heterogeneity, or the doubly censored nature of the dependent variable can generate misleading conclusions.
The Semiclassical propagator for spin coherent states

We use a continuous-time path integral to obtain the semiclassical propagator for minimal-spread spin coherent states. We pay particular attention to the “extra phase” discovered by Solari and Kochetov, and show that this correction is related to an anomaly in the fluctuation determinant. We show that, once this extra factor is included, the semiclassical propagator has the correct short time behavior to O(T2), and demonstrate its consistency under dissection of the path.
Survival of patients with clinically identified monoclonal B-cell lymphocytosis (MBL) relative to the age- and sex-matched general population

Survival of patients with clinically identified monoclonal B-cell lymphocytosis (MBL) relative to the age- and sex-matched general population
An economic analysis of electronic secondary markets: installed base, technology, durability and firm profitability

Abstract The Internet has spawned a number of partially structured electronic secondary markets, which enable the trading of secondary goods between consumers. Many of these, such as Usenet groups, or WWW sites for niche products, tend to be self-administering; however, there has been significant recent growth in the number of more general web-based markets of this kind. These electronic secondary markets, while facilitating reliable and liquid trade of used goods, could also have an impact on the desirability of new products, as well as products that are complementary/compatible to those traded. We present an economic framework for analyzing how these markets affect the demand for a primary product. We examine when it is optimal for a firm to operate a market of this kind, and when its presence is socially optimal. Surprisingly, we find that in a number of cases, the presence of these markets has a primary positive effect on the profitability of a new good; this leads us to conjecture that there will soon be a number of such trading forums operated by manufacturers of primary goods. We also find that in a majority of cases, it is feasible for a third-party intermediary to profitably operate such a market. Key parameters that affect the desirability of the market are the existing installed customer base, the cost of information technology, the durability of the products in question, their rate of technological obsolescence and the nature of customer preferences.
The feasibility of universal grants under democratic capitalism

Today unemployment is a cultural, not an economic problem. By this I mean the following: (1) no economic solution to growing unemployment is in view; (2) if it is not necessary that people perform unpleasant work, they should not be forced to do it; and (3) not working will not be viewed individually and socially as undesirable if certain institutional and cultural changes occur. A central political problem of our times is to transform the deprivation resulting from growing unemployment into a celebration of increasing freedom from unpleasant work ("toil"). The economic preconditions of this transformation are present: this is why we have massive unemployment. Political, cultural, and institutional preconditions are as yet absent: this is why we experience the possibility of freedom as widespread deprivation.
Rent Seeking: A Textbook Example.

Abstract: The author argues that the college textbook market provides a clear example of monopoly seeking as described by Tullock (1967, 1980). This behavior is also known as rent seeking. Because this market is important to students, this example of rent seeking will be of particular interest to them.
The impact of horizontal resolution on moist processes in the ECMWF model

Summer and winter climates simulated with the ECMWF (cycle 33) model at spectral scales T21, T42, T63 and T106 are analyzed to determine the impact of changes in horizontal resolution on atmospheric water vapor, clouds, convection, and precipitation. Qualitative changes in many moist processes occur in the transition from T21 to T42, especially in the tropics; at higher resolutions mostly incremental variations from patterns established at T42 result. Large-scale tropical moist processes are simulated more realistically at T21 than at finer resolutions, possibly reflecting a mismatch between the finer-scale dynamics and the scales at which the underlying assumptions of the physical parameterizations apply. Global precipitation increases monotonically with resolution, as a consequence of increasing convection. Global cloud cover, however, decreases in the transition from T21 to T42 due to drying of the tropics, but then increases slightly at finer resolutions. These small global increases are an outcome of compensating changes in different regions: decreases in cloud cover due to drying of the atmosphere at low latitudes are offset by high-latitude increases resulting from enhanced relative humidity associated with an intensifying atmospheric cold bias at finer resolutions.
Middle paleolithic symbolism: A review of current evidence and interpretations

Abstract Identifying the origins of symbolism and of linguistically structured behavior is crucial to our nderstanding of the evolution of modern humanity. A critical survey of the archaeological data indicates that many aspects of modern adaptation—foresight and planning, affection and mutual assistance, and even a sence of esthetics—are clearly apparent by the Middle Paleolithic. However, currently available evidence fails to indicate the presence of symbolic thought or symbolic behavior before the Middle/Upper Paleolithic transition.
Tidal Interaction between a Fluid Star and a Kerr Black Hole in Circular Orbit

We present a semianalytic study of the equilibrium models of close binary systems containing a Newtonian fluid star (mass m and radius R0) and a Kerr black hole (mass M) in a circular orbit. We consider the limit M m where spacetime is described by the Kerr metric. The tidally deformed star is approximated by an ellipsoid and satisfies the polytropic equation of state. The models also include fluid motion in the stellar interior, allowing binary models with nonsynchronized stellar spin (as expected for coalescing neutron star-black hole binaries) to be constructed. Our relativistic, compressible Roche-Riemann model is a generalization of the incompressible, corotating Roche model studied earlier by Fishbone. Tidal disruption occurs at orbital radius rtide ~ R0(M/m)1/3, but the dimensionless ratio tide = rtide/[R0(M/m)1/3] depends on the spin parameter of the black hole as well as on the equation of state and the internal rotation of the star. We find that the general relativistic tidal field disrupts the star at a larger tide than the Newtonian tide; the difference is particularly prominent if the disruption occurs in the vicinity of the black hole's horizon. In general, tide is smaller for a (prograde rotating) Kerr black hole than for a Schwarzschild black hole. We apply our results to coalescing black hole-neutron star and black hole-white dwarf binaries. The tidal disruption limit is important for characterizing the expected gravitational wave signals and is relevant for determining the energetics of gamma-ray bursts that may result from such disruptions.
Detection of Charged Particles in Amorphous Silicon Layers

The successful development of radiation detectors made from amorphous silicon could offer the possibility for relatively easy construction of large area position-sensitive detectors. We have conducted a series of measurements with prototype detectors, on signals derived from alpha particles. The measurement results are compared with simple model calculations, and projections are made of potential applications in high-energy and nuclear physics.
The Pompeiu problem and discrete groups

We formulate a version of the Pompeiu problem in the discrete group setting. Necessary and sufficient conditions are given for a finite collection of finite subsets of a discrete abelian group, whose torsion free rank is less than the cardinal of the continuum, to have the Pompeiu property. We also prove a similar result for nonabelian free groups. A sufficient condition is given that guarantees the harmonicity of a function on a nonabelian free group if it satisfies the mean-value property over two spheres.
Use of benzynes for the synthesis of heterocycles

About two decades after Kobayashi's discovery in 1983 of a very mild way of generating highly reactive aryne intermediates, the synthetic community embraced o-(trimethylsilyl)aryl triflates as convenient and versatile aryne precursors for the synthesis of carbocycles and heterocycles, as well as natural products and pharmaceutically promising drug candidates. This review provides a comprehensive overview of the construction of heterocycles using Kobayashi's silylaryl triflate aryne precursors. It is organized according to the type of heterocycle generated.
Fish Oil Decreases Macrophage Tumor Necrosis Factor Gene Transcription by Altering the NFκB Activity

Background.Fish oil-supplemented diets have anti-inflammatory and immunomodulating effects, though the exact mechanism(s) are unknown. This study investigated the effects of eicosapentanenoic acid (EPA), a major component of fish oil, on transcriptional regulation of tumor necrosis factor (TNF) gene in lipopolysaccharide (LPS)-stimulated macrophages (MO). Methods.RAW 264.7 cells, a mouse MO cell line, were grown in EPA-rich media for 24–48 h. MO were washed and exposed toEscherichia coliLPS (1 μg/ml) for 2 h. TNF mRNA expression was measured by Northern blot assays. Total nuclear extracts were harvested for the measurement of NFκB with electrophoretic mobility shift assays. Supershift assays were performed with anti-P50 or anti-P65 antibodies to show components of NFκB dimers. TNF production was determined by L929 bioassays. Results.LPS stimulated RAW cell TNF mRNA expression and NFκB activity. In contrast, RAW cells grown in EPA-rich media had less TNF mRNA expression and an altered composition of the NFκB subunits (P65/P50 dimers) in the presence of LPS. TNF production by LPS-stimulated MO was reduced by EPA. Conclusions.The inhibitory effect of EPA on LPS-stimulated MO TNF gene transcription and protein elaboration is, in part, mediated through altering NFκB activation by reducing the P65/P50 dimers.
Surface imaging of III–V semiconductors by reflection electron microscopy and inner potential measurements

Abstract Surfaces of two III–V semiconductor materials have been examined at 120 kV by reflection electron microscopy (REM) at high spatial resolution. Surface steps were found to give characteristics contrast due to several diffraction effects, one of which is interference between the Bragg (B) and Bragg-Laue (BL) reflected beam at a step edge. The electron diffraction pattern from a step showed split lines from B and BL reflections, which provides a method of accurately measuring the mean inner potential of these materials. Electron energy loss spectra showed large surface and bulk plasmon peaks which mainly limit the spatial resolution of REM. The penetration depth in REM is given.
On the coarse-geometric detection of subgroups

We generalize [20] to give sufficient conditions, primarily on coarse geometry, to ensure that a subset of a Cayley graph is a finite Hausdorff distance from a subgroup. Using this result, we prove a partial converse to the Flat Torus Theorem for CAT(0) groups. Also using this result, we give sufficient conditions for subgroups and splittings to be invariant under quasi-isometries.
Prospects for the Habitability of OGLE-2006-BLG-109L

The extrasolar system OGLE-2006-BLG-109L is the first multiple-planet system to be discovered by gravitational microlensing (reported by Gaudi et al. in 2008); the two large planets that have been detected have mass ratios, semimajor axis ratios, and equilibrium temperatures that are similar to those of Jupiter and Saturn; the mass of the host star is only 0.5 M☉, and the system is more compact than our own solar system. We find that in the habitable zone of the host star, the two detected planets resonantly excite large orbital eccentricities on a putative Earth-mass planet, driving such a planet out of the habitable zone. We show that an additional inner planet of 0.3 M⊕ at 0.1 AU would suppress the eccentricity perturbation and greatly improve the prospects for habitability of the system. Thus, the planetary architecture of a potentially habitable OGLE-2006-BLG-109L planetary system—with two "terrestrial" planets and two Jovian planets—could bear very close resemblance to our own solar system.
An empirical approximation to the Voigt profile

Abstract A closed-form approximation to the Voigt profile is developed from an examination of Voigt profile calculations. This approximation matches the Voigt profile within 5 per cent at worst and is generally within 3 per cent or less. In radiant energy transport calculations this approximation is shown to closely reproduce the curves of growth given by use of the Voigt profile expression.
Radial Alignment of Cluster Galaxies

We report the discovery of a statistically significant radial alignment of cluster galaxies in a sample of 85 X-ray-selected clusters observed in the Sloan Digital Sky Survey. The tendency for alignment is a robust feature of our sample and does not vary significantly with individual cluster or galaxy properties. We use dynamical arguments to show that a significant fraction of cluster galaxies should be undergoing a parametric tidal resonance that can cause their long axes to orient themselves toward the center of the cluster potential, and therefore tentatively ascribe the observed radial alignment to this dynamical effect.
Reliability and the computer

The subject of reliability and the modern-day computer is far reaching and complex. The difficulties of designing and manufacturing computing devices which themselves exhibit long intervals of trouble-free operation are now fairly well understood, but many kinds of applications are yet to come in which a computer is but part of a larger system. For these, the consequences to the computer of a requirement for a reliable system may not yet be known. To some, reliability and a computer are mutually exclusive, but existing computing devices do operate trouble-free for long periods, and it is more than an accident that this is the case. This paper reviews a few salient aspects of the computer reliability problem, contributes a new view-point to some parts of the reliability question, and suggests areas where the techniques of the previous papers may be pertinent.
Chiral de Rham complex and orbifolds

Suppose that a finite group G acts on a smooth complex variety X. Then this action lifts to the Chiral de Rham Complex ! ch of X and to its cohomology by automorphisms of the vertex algebra structure. We define twisted sectors for ! ch (and their cohomologies) as sheaves of twisted vertex algebra modules supported on the components of the fixed-point sets X g ,g! G. Each twisted sector sheaf carries a BRST di" erential and is quasi-isomorphic to the de Rham complex of X g . Putting the twisted sectors together with the vacuum sector and taking G-invariants, we recover the additive and graded structures of Chen-Ruan orbifold cohomology. Finally, we show that the orbifold elliptic genus is the partition function of the direct sum of the cohomologies of the twisted sectors.
Canonical quantization of spherically symmetric dust collapse

Quantum gravity effects are likely to play a crucial role in determining the outcome of gravitational collapse during its final stages. In this contribution we will outline a canonical quantization of the LeMaitre-Tolman-Bondi (LTB) models, which describe the collapse of spherical, inhomogeneous, non-rotating dust. Although there are many models of gravitational collapse, this particular class of models stands out for its simplicity and the fact that both black holes and naked singularity end states may be realized on the classical level, depending on the initial conditions. We will obtain the appropriate Wheeler-DeWitt equation and then solve it exactly, after regularization on a spatial lattice. The solutions describe Hawking radiation and provide an elegant microcanonical description of black hole entropy, but they raise other questions, most importantly concerning the nature of gravity’s fundamental degrees of freedom.
From continuous improvement to continuous innovation

The aim of this paper is to demonstrate the need for an alternative to how those in the quality community think about continuous improvement in those business environments characterized by rapid change and uncertainty. This involves a re-examination of the role of error and a recognition of the weakness of conventional marketing techniques in understanding customer needs. Compared with conventional thinking about continuous improvement, the probe-and-learn process and rapid prototyping are presented as better suited to dynamic but uncertain business environments. Probe-and-learn is seen as a new form of Plan Do Check Act (PDCA) that underweights ‘Plan’ and overweights ‘Do’ in a rapid-fire iterative process. The author examines Beta testing as a mode of probe-and-learn. Finally it is argued that probe-and-learn is applicable throughout the production chain.
General equilibrium effects of investment incentives in Mexico

Mexico has experimented with several tax instruments designed to promote private capital formation. Among such initiatives were general and industry-specific tax credits, employment tax credits, and corporate tax credits. The authors examine relative efficacy of such instruments using a dynamic computable general equilibrium model. They carry out model simulations using three equal-yield investment incentive scenarios: increases in investment tax credits, increases in employment tax credits, and an equivalent reduction in the corporate tax rate. The authors present outlines of the tax policy environment with model details and they highlight alternate tax incentives regimes. Conclusions and summary results are provided by the authors.
A social psychological critique of the Saudi terrorism risk reduction initiative

Of great concern to policy makers and detention system administrators who face the need to release detainees suspected of terrorism is how to do so in ways that minimize risk to national security. Among responses taken by detention system administrators is the establishment of so-called ‘deradicalization’ (or ‘disengagement,’ or ‘terrorism risk reduction’) programs in which select detainees may participate to promote their own release. The present analysis critiques the Saudi terrorism risk reduction initiative in accord with two social psychological theories that are especially pertinent to the topic – identity theory and frame alignment theory – and offers policy suggestions based upon the theoretical strengths and weaknesses of the Saudi model.
Combinatorial chemistry: mixture-based combinatorial libraries of acyclic and heterocyclic compounds from amino acids and short peptides.

Combinatorial chemistry is recognized worldwide as a powerful technology for drug discovery. This technology has gained wide acceptance by most pharmaceutical and biotechnology companies as well as academia [1-2]. The power of combinatorial chemistry lies in its ability to accelerate the drug discovery process through the rapid synthesis and subsequent screening of a larger number of compounds than previously possible. In a recent paper on combinatorial libraries, we reviewed the solid-phase chemistry used to prepare small molecule and heterocyclic mixture-based libraries [3]. Herein we provide a perspective on synthetic combinatorial approaches using mixture-based libraries, as well as an illustration of our work in the generation of libraries of acyclic and heterocyclic compounds from amino acids and/or short peptides.
Securing the Exocortex: A Twenty-First Century Cybernetics Challenge

An exocortex is a wearable (or implanted) computer used to augment a brain?s biological high-level cognitive processes and inform a user?s decisions and actions. Brain-computer interfaces (BCIs) are a special type of exocortex used to interact with the environment via neural signals. Uses for BCI range from medical applications and rehabilitation to operation of assistive devices. They can also be used for marketing, gaming, and for entertainment, where BCIs are used to provide users with a more personalized experience.
An efficient and chemoselective iron catalyst for the hydrogenation of ketones.

Iron complex 1 containing electronically coupled acidic and hydridic hydrogens catalyzes the hydrogenation of ketones under mild conditions. This hydrogenation catalyst shows high chemoselectivity for aldehydes, ketones, and imines, and isolated CC, C⋮C, C−X, −NO2, epoxides, and ester functions are unaffected by the hydrogenation conditions. Mechanistic studies have established a reversible hydrogen transfer step followed by rapid dihydrogen activation. The same iron complex also catalyzes transfer hydrogenation of ketones.
Quasi-Experimental Price Elasticity of Liquor Demand in the United States: 1960–83

This paper uses sixty-five recent tax changes on liquor in private licensed states over the period 1960–83 to update Simon's quasi-experimental price elasticity of liquor. Three alternative measures for liquor price are used, and the sensitivity of this price elasticity to border effect purchases as well as market changes over time are examined. Our results support a liquor price elasticity estimate of −.7. However, the confidence interval on this estimate is wide. Border effect purchases as well as changes in the liquor market over time are statistically insignificant.
Tensile failure of fibrous composites.

Failure of composite consisting of matrix stiffened by uniaxially oriented fibers, when subjected to uniaxial tensile load parallel to fiber direction
Iron Lewis Acid Catalyzed Reactions of Aromatic Aldehydes with Ethyl Diazoacetate: Unprecedented Formation of 3-Hydroxy-2-arylacrylic Acid Ethyl Esters by a Unique 1,2-Aryl Shift

The iron Lewis acid [η5-(C5H5)Fe(CO)2(THF)]BF4 (1) was found to catalyze reactions of ethyl diazoacetate (EDA) and aromatic aldehydes, yielding 3-hydroxy-2-arylacrylic acid ethyl esters and the corresponding β-keto esters. According to the literature, this is the first report of the formation of enol esters from EDA and aromatic aldehydes. The yield of the enol esters increased with electron-rich aldehydes. With 2,4-dimethoxybenzaldehyde the only product isolated was the corresponding enol ester in 80% yield. However, in the presence of electron-deficient aldehydes such as p-nitrobenzaldehyde, formation of enol ester decreased to 32%. The most unique feature of these reactions is that enol esters are formed by an unusual 1,2-aryl shift, from a possible intermediate 8, which in turn is formed from the reaction of the iron aldehyde complex 7 and EDA.
On the Snow Line in Dusty Protoplanetary Disks

C. Hayashi prescribed a "minimum-mass solar nebula," which contained just enough material to make the planets. This prescription, which has been widely used in constructing scenarios for planet formation, proposed that ice will condense when the temperature falls below 170 K (the "snow line"). In Hayashi's model, that occurred at 2.7 AU. It is usually assumed that the cores of the giant planets (e.g., Jupiter) form beyond the snow line. The snow line, in Hayashi's model, is where the temperature of a black body that absorbed direct sunlight and reradiated as much as it absorbed would be 170 K. Since Hayashi, there have been a series of more detailed models of the absorption by dust of the stellar radiation and of accretional heating, which alter the location of the snow line. We have attempted a "self-consistent" model of a T Tauri disk in the sense that we used dust properties and calculated surface temperatures that matched observed disks. We then calculated the midplane temperature for those disks, with no accretional heating or with small (≤10-8 M☉ yr-1) accretion rates. (Larger accretion rates can push the snow line out to beyond 4 AU but do not match the observed disks.) Our models bring the snow line in to the neighborhood of 1 AU—not far enough to explain the close planetary companions to other stars, but much closer than in recent starting lines for orbit migration scenarios.
Inequivalent quantizations of Yang-Mills theory on a cylinder

Abstract Yang-Mills theories on a (1+1)-dimensional cylinder are considered. It is shown that canonical quantization can proceed following different routes, leading to inequivalent quantizations. The problem of the non-free action of the gauge group on the configuration space is also discussed. In particular we re-examine the relationship between “θ-states” and the fundamental group of the configuration space. It is shown that this relationship does or does not hold depending on whether or not the gauge transformations not connected to the identity act freely on the space of connections modulo connected gauge transformations.
Modified Afshar experiment: calculations

The Afshar experiment is a relatively simple two-slit experiment with results that show a discrepancy with the predictions of Bohr's Principle of Complementarity. We report on the results of a calculation using a simpler but equivalent set-up called the modified Afshar experiment. Numerical results are in agreement with the experimental measurements performed on the Afshar experiment set-up. Calculations show that the level of which-way information and visibility in the Afshar experiment is higher than originally estimated.
Meromorphic solutions to a differential-difference equation describing certain self-similar potentials

In this paper we prove the existence of meromorphic solutions to a nonlinear differential difference equation that describe certain self-similar potentials for the Schrodinger operator.
Interstellar Dust Models Consistent with Extinction, Emission, and Abundance Constraints

We present new interstellar dust models which have been derived by simultaneously fitting the far ultraviolet to near infrared extinction, the diffuse infrared emission, and, unlike previous models, the elemental abundances in dust for the diffuse interstellar medium. We found that dust models consisting of a mixture of spherical graphite and silicate grains, polycyclic aromatic hydrocarbon (PAH) molecules, in addition to porous composite particles containing silicate, organic refractory, and water ice, provide an improved .t to the UV-to-infrared extinction and infrared emission measurements, while consuming the amounts of elements well within the uncertainties of adopted interstellar abundances, including B star abundances. These models are a signi.cant improvement over the recent Li & Draine (2001, ApJ, 554, 778) model which requires an excessive amount of silicon to be locked up in dust: 48 ppm (atoms per million of H atoms), considerably more than the solar abundance of 34 ppm or the B star abundance of 19 ppm.
The heterotic string is a soliton

Abstract It is shown that the Type IIA superstring compactified on K 3 has a smooth string soliton with the same zero mode structure as the heterotic string compactified on a four-torus, thus providing new evidence for a conjectured exact duality between the two six-dimensional string theories. The chiral worldsheet bosons arise as zero modes of Ramond-Ramond fields of the IIA string theory and live on a signature (20,4) even, self-dual lattice. Stable, finite loops of soliton string provide the charged Ramond-Ramond states necessary for enhanced gauge symmetries at degeneration points of the K 3 surface. It is also shown that Type IIB strings toroidally compactified to six dimensions have a multiplet of string solutions with Type II worldsheets.
Concepts for more efficient bulkhead designs for launch and space vehicles.

Low profile bulkheads for launch vehicles and spacecraft compartments to obtain structural weight reduction
Flight Effects on Fan Noise with Static and Wind-Tunnel Comparisons

A flight test program utilizing a JT15D-1 turbofan engine has been conducted with the objectives of studying flight effects on fan noise and evaluating the simulation effectiveness of both a wind tunnel and a static test configuration that incorporated an inlet control device (ICD). In conjunction with synchronized laser-radar tracking and meteorological profile information, data obtained from a linear array of ground microphones was narrowband-analyzed and ensemble-averaged to yield highly accurate far-field flight acoustic results. Utilizing appropriate corrections, flight, wind tunnel, and static acoustic data were normalized to a static-equivalent, 100-foot radius, lossless reference condition. Data comparisons showed that both the static test with ICD and wind tunnel were generally very effective in simulating flight blade-passage-frequency (BPF) noise levels. However, differences were observed in broadband noise levels and in the details of the multiple-pure-tone harmonics.
Factoring the Becker-Gottlieb Transfer Through the Trace Map

We verify the Becker-Shultz axioms characterizing the Becker-Gottlieb transfer $\tau$ for the composite of the algebraic $\Kof$-theory transfer of any perfect fibration followed by the trace map. As a consequence, for any compact ANR fibration (those considered by Becker-Shultz), $\tau$ is homotopy equivalent to the composite of the algebraic $\Kof$-theory transfer followed by the trace map. Furthermore, if these same axioms (including strong additivity) could be shown to extend to characterizing $\tau$ for arbitrary perfect fibrations, our homotopy equivalence extends to the case of arbitrary perfect fibrations as well.
Primary hyperoxaluria. A frequently unappreciated cause of chronic renal failure.

Primary hyperoxaluria is an inherited autosomal recessive disease leading to renal failure at various ages due to calcium oxalate deposition. Often, frequent stones at an early age are the first manifestation of the disease. Other tissues may be damaged from tissue deposits after renal failure develops. Therapy is directed at providing a normal glomerular filtration rate and oxalate excretion with a functioning graft, combined with measures to reduce oxalate production or precipitation in the urine and kidney. The disease may be a more frequent cause of renal failure than previously recognized and needs to be considered when the clinical findings are suggestive. Although there is an increased risk of recurrence of the disease in the transplanted kidney, with subsequent graft damage and loss, transplantation can be successful in a significant percentage of patients by using techniques that will optimize graft function and reduce the metabolic load of oxalate.
L2C2: logic-based LSC consistency checking

Live sequence charts (LSCs) have been proposed as an inter-object scenario-based specification and visual programming language for reactive systems. In this paper, we introduce a logic-based framework to check the consistency of an LSC specification. An LSC simulator has been implemented in logic programming, utilizing a memoized depth-first search strategy, to show how a reactive system in LSCs would response to a set of external event sequences. A formal notation is defined to specify external event sequences, extending the regular expression with a parallel operator and a testing control. The parallel operator allows interleaved parallel external events to be tested in LSCs simultaneously; while the testing control provides users to a new approach to specify and test certain temporal properties (e.g., CTL formula) in a form of LSC. Our framework further provides either a state transition graph or a failure trace to justify the consistency checking results.
Cross sections, relic abundance, and detection rates for neutralino dark matter.

Neutralino annihilation and elastic scattering cross sections are derived which differ in important ways from previous work. These are applied to relic abundance calculations and to direct detection of neutralino dark matter from the galactic halo. Assuming the neutralino to be the lightest supersymmetric particle and that it is less massive than the Z sup 0, we find relic densities of neutralinos greater than 4 percent of critical density for almost all values of the supersymmetric parameters. We constrain the parameter space by using results from PETRA (chargino mass less than 23 GeV) and ASP, and then assuming a critical density of neutralinos, display event rates in a cryogenic detector for a variety of models. A new term implies spin independent elastic scattering even for those majorana particles and inclusion of propagator momenta increases detection rates by 10 to 300 percent for pure photinos. Z sup 0-squark interference leads to very low detection rates for some values of the parameters. The new term in the elastic cross section dominates for heavy, mostly spinless materials and mitigates the negative interference cancellations in light materials; except for the pure photino or pure higgsinos cases where it does not contribute. In general, the rates can be substantially different from the pure photino and pure higgsino special cases usually considered.
A local proton irradiation model for isotopic anomalies in the solar system.

This paper attempts to explain the /sup 16/O and /sup 26/Al isotopic anomalies found in planetary bodies of the solar system by a local irradiation model. In this model a small parcel (approx.3 x 10/sup 25/g) of solar system matter of normal isotopic composition was irradiated by protons from the primeval Sun with a total flux F=2.2 x 10/sup 25/ cm/sup -2/ and an energy spectrum dPhi/dE=KE/sup -4.5/ for E> or approx. =2MeV. Most of the /sup 17/O and /sup 18/O in the target was destroyed by (p, ..cap alpha..) reactions so that only /sup 16/O survived, while /sup 26/Al was produced by the (p, n) reaction on /sup 26/Mg. The irradiated matter was mixed incompletely with the unirradiated matter to form planetary bodies. If the irradiated material has a particular elemental composition such that the H and rare gases are depleted relative to oxygen by a factor of 10/sup 3/ and the heavy elements (Z>10) are depleted by a factor of 50, then this model can be used to explain the /sup 16/O and /sup 26/Al anomalies quantitatively and is consistent with the nearly normal Mg, Ca, and Ba observed in most of the samples. This model requires 3%more » of the solar gravitational energy and does not suffer the self-shielding problem. Although these requirements are ad hoc, the proton irradiation model still appears to be a possible alternative to the super-nova models for the isotopic anomalies. However, it does not seem to explain the /sup 48/Ca excess recently discovered in a rare class of meteoritic objects. A search for the anomalies in La expected from this model should provide a definitive test.« less
A Color Analysis of the NICMOS Parallel Image Archive

We present a photometric analysis of all high Galactic latitude (|b| > 20°) broadband parallel images taken by the Near-Infrared Camera and Multi-Object Spectrometer instrument of the Hubble Space Telescope during its initial lifetime in HST Cycle 7. These images, taken through the F110W and F160W filters, reach a mean 3 σ limiting magnitude of approximately 22 in both bands, and cover a total area of approximately 92 arcmin2. The reddest of the 358 galaxies detected have F110W-F160W colors and F160W magnitudes consistent with being a combination of both dusty star-forming and evolved early-type galaxies at 1 z 2. The surface density of these galaxies is comparable to that of the population of extremely red objects (EROs) discovered in ground-based surveys (~100 deg-2), suggesting that EROs also represent a combination of both galaxy types in this redshift range. Roughly 10% of the detected galaxies appear to be blue compact dwarf galaxies at z 1, a result consistent with studies of the HST Medium Deep Survey fields. The surface density of these objects down to a magnitude of 22 in F160W is ~300 deg-2. None of the 631 point sources detected have F110W-F160W colors matching those expected for quasi-stellar objects (QSOs) whose continua have been significantly reddened by internal dust. Our data limit the surface density of such QSOs to be 50 deg-2 down to the mean limiting magnitudes of the sample images. Since the surface density of QSOs detected on the basis of ultraviolet excess in optical surveys to comparable depth is ~100 deg-2, this argues against the suggestion that dust-reddened QSOs compose the undetected majority of the QSO population. The F110W-F160W color can also be used to identify unreddened QSOs at z 8, but we find no such candidates. This is consistent with the evidence that QSO space density declines sharply at z 5.
Taming Uncertainties in Real-Time Routing for Wireless Networked Sensing and Control

Real-time routing is a basic element of closed-loop, real-time sensing and control, but it is challenging due to dynamic, uncertain link/path delays. The probabilistic nature of link/path delays makes the basic problem of computing the probabilistic distribution of path delays NP-hard, yet quantifying probabilistic path delays is a basic element of real-time routing and may well have to be executed by resource-constrained devices in a distributed manner; the highly varying nature of link/path delays makes it necessary to adapt to in-situ delay conditions in real-time routing, but it has been observed that delay-based routing can lead to instability, estimation error, and low data delivery performance in general. To address these challenges, we propose the Multi-Timescale Estimation (MTE) method; by accurately estimating the mean and variance of per-packet transmission time and by adapting to fast-varying queueing in an accurate, agile manner, MTE enables accurate, agile, and efficient estimation of probabilistic path delay bounds in a distributed manner. Based on MTE, we propose the Multi-Timescale Adaptation (MTA) routing protocol; MTA integrates the stability of an ETX-based directed-acyclic-graph (DAG) with the agility of spatiotemporal data flow control within the DAG to ensure real-time data delivery in the presence of dynamics and uncertainties. We also address the challenges of implementing MTE and MTA in resource-constrained devices such as TelosB motes. We evaluate the performance of MTA using the NetEye and Indriya sensor network testbeds. We find that MTA significantly outperforms existing protocols, e.g., improving deadline success ratio by 89% and reducing transmission cost by a factor of 9.7 in the NetEye testbed.
Household-level determinants of adoption of improved natural resources management practices among smallholder farmers in western Kenya

Abstract Integrated natural resources management (INRM), of which integrated soil fertility management (ISFM) is a component, offers considerable promise for increasing food production in Kenya. It nonetheless remains unclear whether ISFM/INRM techniques lend themselves easily to adoption by smallholder farmers. Using panel data collected in western Kenya in 1989 and 2002, this study finds that resource constraints limit many farmers’ adoption of ISFM/INRM techniques. The size of the farm owned by a household, the value of its livestock, off-farm income, family labor supply, and the educational attainment and gender of the household head all had a significant positive effect on the likelihood of adoption. Similar factors were found to be statistically significant in discouraging abandonment of the practices under study. There thus seem to exist reinforcing feedback between investments in soil fertility management and household wealth, as measured by asset endowments. Our findings raise important questions as to whether ISFM and related techniques are really affordable to poorer smallholder farmers.
Analysis of engine usage data for tactical systems

Turbine engine field experience has demonstrated a need to consider realistic engine usage profiles and duty cycles in the preliminary design phase of development. The increased emphasis on understanding usage is a result of hardware failures in today's engines brought on by aircraft/engine usage that is considerably different than design. Recognizing this need, the Aero Propulsion Laboratory recorded a limited amount of data and used it to identify driving parameters on engine usage. This paper presents results of data analysis from continuously recorded engine/aircraft parameters on F-15, F-5E, and A-10 aircraft. These aircraft were flown in Red Flag combat training exercises, normal training, and check flight sorties. Pilot debriefs were obtained. These identify specific flight events which impact usage.
A Parallel Algorithm for Mesh Smoothing

Maintaining good mesh quality during the generation and refinement of unstructured meshes in finite-element applications is an important aspect in obtaining accurate discretizations and well-conditioned linear systems. In this article, we present a mesh-smoothing algorithm based on nonsmooth optimization techniques and a scalable implementation of this algorithm. We prove that the parallel algorithm has a provably fast runtime bound and executes correctly for a parallel random access machine (PRAM) computational model. We extend the PRAM algorithm to distributed memory computers and report results for two- and three-dimensional simplicial meshes that demonstrate the efficiency and scalability of this approach for a number of different test cases. We also examine the effect of different architectures on the parallel algorithm and present results for the IBM SP supercomputer and an ATM-connected network of SPARC Ultras.
Gunrock: a high-performance graph processing library on the GPU

For large-scale graph analytics on the GPU, the irregularity of data access/control flow and the complexity of programming GPUs have been two significant challenges for developing a programmable high-performance graph library. "Gunrock," our high-level bulk-synchronous graph-processing system targeting the GPU, takes a new approach to abstracting GPU graph analytics: rather than designing an abstraction around computation, Gunrock instead implements a novel data-centric abstraction centered on operations on a vertex or edge frontier. Gunrock achieves a balance between performance and expressiveness by coupling high-performance GPU computing primitives and optimization strategies with a high-level programming model that allows programmers to quickly develop new graph primitives with small code size and minimal GPU programming knowledge. We evaluate Gunrock on five graph primitives (BFS, BC, SSSP, CC, and PageRank) and show that Gunrock has on average at least an order of magnitude speedup over Boost and PowerGraph, comparable performance to the fastest GPU hardwired primitives, and better performance than any other GPU high-level graph library.
Adaptive and robust controls of uncertain systems with nonlinear parameterization

Two classes of partially known systems are considered in this note; both of them have a fractional parameterization of the unknowns. The first class consists of nonlinear systems whose uncertainties are bounded by a function of fractional parameterization, and the second class compromises those systems whose unknown dynamics can directly, but nonlinearly, be parameterized. It is shown that adaptive robust control can be extended to accommodate nonlinearly parameterized bounding functions and that, with the aid of a robust auxiliary system, new adaptation laws and a simple adaptive control can be designed for the unknowns in the fractional parameterization. Practical stability (in terms of uniform boundedness and ultimate boundedness) is shown; global for adaptive robust control and semiglobal for the new adaptive control.