cssi/SciSciGPT-SciSciNet huggingface dataset:
Detecting Primordial Stars

We discuss the expected properties of the first stellar generations in the Universe. We find that it is possible to discern truly primordial populations from the next generation of stars by measuring the metallicity of high-z star forming objects. The very low background of the future James Webb Space Telescope (JWST) will enable it to image and study first-light sources at very high redshifts, whereas its relatively small collecting area limits its capability in obtaining spectra of z~10-15 first-light sources to either the bright end of their luminosity function or to strongly lensed sources. With a suitable investment of observing time JWST will be able to detect individual Population III supernovae, thus identifying the very first stars that formed in the Universe.
Dynamic Complexity of Planar 3-Connected Graph Isomorphism

Dynamic Complexity (as introduced by Patnaik and Immerman [14]) tries to express how hard it is to update the solution to a problem when the input is changed slightly. It considers the changes required to some stored data structure (possibly a massive database) as small quantities of data (or a tuple) are inserted or deleted from the database (or a structure over some vocabulary). The main difference from previous notions of dynamic complexity is that instead of treating the update quantitatively by finding the the time/space trade-offs, it tries to consider the update qualitatively, by finding the complexity class in which the update can be expressed (or made). In this setting, DynFO, or Dynamic First-Order, is one of the smallest and the most natural complexity class (since SQL queries can be expressed in First-Order Logic), and contains those problems whose solutions (or the stored data structure from which the solution can be found) can be updated in First-Order Logic when the data structure undergoes small changes.
Extreme Starbursts and Molecular Clouds in Galaxies

The extraordinary starbursts found in ultraluminous IR galaxies occur in molecular gas concentrated in compact very massive “clouds” which we call “Extreme Starbursts”. They have one thousand times the mass but are only a few times larger than GMCs. High-mass star formation in sufficiently dense and massive structures does not disrupt further star formation; it is a runaway process. Star formation remains embedded in the molecular gas and there is little or virtually no optical-UV radiation. In the early universe extreme starbursts may be more frequent and they may be the mode of star formation in high redshift submillimeter sources.
Clinical Decision Support to Improve Antibiotic Prescribing for Acute Respiratory Infections: Results of a Pilot Study

Acute Respiratory Infections (ARIs) are the number one reason for antibiotic prescribing in the United States, and much antibiotic prescribing for ARIs is inappropriate. We designed an electronic health record-integrated, documentation-based clinical decision support system for the care of patients with ARIs, the ARI Smart Form. To evaluate the ARI Smart Form and assess the feasibility of performing a larger trial, we conducted a pilot study with 10 clinicians who used the ARI Smart Form with 26 patients. Clinicians prescribed antibiotics to 6 of 6 patients with antibiotic-appropriate diagnoses and to 3 of 20 (15%) patients with antibiotic-inappropriate diagnoses. The average duration of use of the ARI Smart Form was 7.5 (SD±4.5) minutes. Eight of 10 respondents reported that the ARI Smart Form was either time-neutral or timesaving. The ARI Smart Form requires further evaluation but has the potential to improve workflow and reduce inappropriate antibiotic prescribing.
Regioselective aerobic oxidative Heck reactions with electronically unbiased alkenes: efficient access to α-alkyl vinylarenes

Branched-selective oxidative Heck coupling reactions have been developed between arylboronic acids and electronically unbiased terminal alkenes. The reactions exhibit high catalyst-controlled regioselectivity favoring the less common branched isomer. The reactions employ a catalyst composed of Pd(TFA)2/dmphen (TFA = trifluoroacetate, dmphen = 2,9-dimethyl-1,10-phenanthroline) and proceed efficiently at 45-60 °C under 1 atm of O2 without requiring other additives. A broad array of functional groups, including aryl halide, allyl silane and carboxylic acids are tolerated.
Genome-Wide Mapping and Interrogation of the Nmp4 Antianabolic Bone Axis

PTH is an osteoanabolic for treating osteoporosis but its potency wanes. Disabling the transcription factor nuclear matrix protein 4 (Nmp4) in healthy, ovary-intact mice enhances bone response to PTH and bone morphogenetic protein 2 and protects from unloading-induced osteopenia. These Nmp4(-/-) mice exhibit expanded bone marrow populations of osteoprogenitors and supporting CD8(+) T cells. To determine whether the Nmp4(-/-) phenotype persists in an osteoporosis model we compared PTH response in ovariectomized (ovx) wild-type (WT) and Nmp4(-/-) mice. To identify potential Nmp4 target genes, we performed bioinformatic/pathway profiling on Nmp4 chromatin immunoprecipitation sequencing (ChIP-seq) data. Mice (12 w) were ovx or sham operated 4 weeks before the initiation of PTH therapy. Skeletal phenotype analysis included microcomputed tomography, histomorphometry, serum profiles, fluorescence-activated cell sorting and the growth/mineralization of cultured WT and Nmp4(-/-) bone marrow mesenchymal stem progenitor cells (MSPCs). ChIP-seq data were derived using MC3T3-E1 preosteoblasts, murine embryonic stem cells, and 2 blood cell lines. Ovx Nmp4(-/-) mice exhibited an improved response to PTH coupled with elevated numbers of osteoprogenitors and CD8(+) T cells, but were not protected from ovx-induced bone loss. Cultured Nmp4(-/-) MSPCs displayed enhanced proliferation and accelerated mineralization. ChIP-seq/gene ontology analyses identified target genes likely under Nmp4 control as enriched for negative regulators of biosynthetic processes. Interrogation of mRNA transcripts in nondifferentiating and osteogenic differentiating WT and Nmp4(-/-) MSPCs was performed on 90 Nmp4 target genes and differentiation markers. These data suggest that Nmp4 suppresses bone anabolism, in part, by regulating IGF-binding protein expression. Changes in Nmp4 status may lead to improvements in osteoprogenitor response to therapeutic cues.
When gravity fails: local search topology

Local search algorithms for combinatorial search problems frequently encounter a sequence of states in which it is impossible to improve the value of the objective function; moves through these regions, called plateau moves, dominate the time spent in local search. We analyze and characterize plateaus for three different classes of randomly generated Boolean Satisfiability problems. We identify several interesting features of plateaus that impact the performance of local search algorithms. We show that local minima tend to be small but occasionally may be very large. We also show that local minima can be escaped without unsatisfying a large number of clauses, but that systematically searching for an escape route may be computationally expensive if the local minimum is large. We show that plateaus with exits, called benches, tend to be much larger than minima, and that some benches have very few exit states which local search can use to escape. We show that the solutions (i.e., global minima) of randomly generated problem instances form clusters, which behave similarly to local minima. We revisit several enhancements of local search algorithms and explain their performance in light of our results. Finally we discuss strategies for creating the next generation of local search algorithms.
Polarization-induced Zener tunnel diodes in GaN/InGaN/GaN heterojunctions

By the insertion of thin InxGa1−xN layers into Nitrogen-polar GaN p-n junctions, polarization-induced Zener tunnel junctions are studied. The reverse-bias interband Zener tunneling current is found to be weakly temperature dependent, as opposed to the strongly temperature-dependent forward bias current. This indicates tunneling as the primary reverse-bias current transport mechanism. The Indium composition in the InGaN layer is systematically varied to demonstrate the increase in the interband tunneling current. Comparing the experimentally measured tunneling currents to a model helps identify the specific challenges in potentially taking such junctions towards nitride-based polarization-induced tunneling field-effect transistors.
Track-before-detect performance for a high PRF search mode

The performance of a four-stage track-before-detect algorithm used for an X-band high pulse repetitive frequency (PRF) search mode is evaluated. A dynamic programming algorithm is used to noncoherently integrate over resolution cells lying along each potential target path, and path sums are compared to a threshold to determine if a target is present. Given a threshold setting that results in a false track generation rate of 10/sup 6/ per resolution cell, track detections are obtained with probability 0.5 at a signal-to-noise ratio of about 8.7 dB for a target closing at 2.5 nmi per revisit time, assuming a Swerling I or II Rayleigh signal plus noise model as measured after transforming to Doppler-range space. For the same threshold setting, 90% of the tracks were detected at signal-to-noise ratios (SNRs) of 9.6 dB or smaller. If the closing range is decreased to 0.25 nmi per revisit time, then track detections occur with probability 0.5 at a SNR of 8.1 dB, and 90% of the tracks were detected at SNRs of 5.5 dB smaller. >
Tip110 Regulates the Cross Talk between p53 and Hypoxia-Inducible Factor 1α under Hypoxia and Promotes Survival of Cancer Cells

Hypoxia often occurs under various physiological and pathophysiological conditions, including solid tumors; it is linked to malignant transformation, metastatic progression, and treatment failure or resistance. Tip110 protein plays important roles in several known physiological and pathophysiological processes, including cancers. Thus, in the present study we investigated the regulation of Tip110 expression under hypoxia. Hypoxia led to Tip110 protein degradation through the ubiquitin-proteasome system. Under hypoxia, Tip110 stabilized p53, which in return destabilized Tip110. In addition, Tip110 regulated hypoxia-inducible factor 1α (HIF-1α), likely through enhancement of its protein stability. Furthermore, Tip110 upregulated p300, a known coactivator for both p53 and HIF-1α. Expression of a p53(22/23) mutant deficient in p300 binding accelerated Tip110 degradation under hypoxia. Tip110 knockdown resulted in the inhibition of cell proliferation and cell death in the presence of p53. Finally, significantly less Tip110, p53, and HIF-1α was detected in the hypoxic region of bone metastasis tumors in a mouse model of human melanoma cells. Taken together, these results suggest Tip110 is an important mediator in the cross talk between p53 and HIF-1α in response to hypoxic stress.
On modeling profiles instead of values

We consider the problem of estimating the distribution underlying an observed sample of data. Instead of maximum likelihood, which maximizes the probability of the observed values, we propose a different estimate, the high-profile distribution, which maximizes the probability of the observed profile---the number of symbols appearing any given number of times. We determine the high-profile distribution of several data samples, establish some of its general properties, and show that when the number of distinct symbols observed is small compared to the data size, the high-profile and maximum-likelihood distributions are roughly the same, but when the number of symbols is large, the distributions differ, and high-profile better explains the data.
Do land market restrictions hinder structural change in a rural economy ? evidence from Sri Lanka

This paper analyzes the effects of land market restrictions on structural change from agriculture to non-farm in a rural economy. This paper develops a theoretical model that focuses on higher migration costs due to restrictions on alienability, and identifies the possibility of a reverse structural change where the share of nonagricultural employment declines. The reverse structural change can occur under plausible conditions: if demand for the non-agricultural good is income-inelastic (assuming the non-farm good is non-tradable), or non-agriculture is less labor intensive relative to agriculture (assuming the non-farm good is tradable). For identification, this paper exploits a natural experiment in Sri Lanka where historical malaria played a unique role in land policy. The empirical evidence indicates significant adverse effects of land restrictions on manufacturing and services employment, rural wages, and per capita household consumption. The evidence on the disaggregated occupational choices suggests that land restrictions increase wage employment in agriculture, but reduce it in manufacturing and services, with no perceptible effects on self-employment in non-agriculture. The results are consistent with the migration costs model, but contradict two widely discussed alternative mechanisms: collateral effect and property rights insecurity. This paper also provides direct evidence in favor of the migration costs mechanism.
Progress in the development of lightweight nickel electrode

The use of the lightweight nickel electrode, in place of the heavy-sintered state-of-the-art nickel electrode, will lead to improvements in specific energy and performance of the nickel-hydrogen cell. Preliminary testing indicates that a nickel fiber mat is a promising support candidate for the nickel hydroxide active material. Nickel electrodes made from fiber mats, with nickel and cobalt powder added to the fiber, were treated at NASA Lewis Research Center. To date, over 8000 cycles have been accumulated, at 40% depth-of-discharge, using the lightweight fiber electrode, in a boiler plate nickel-hydrogen cell. >
Clostridia, Solvent Formation

Introduction Physiology and Biochemistry of the Solvent Fermentations Clostridium's General Fermentation Strategy Ethanol Fermentations Butanol Fermentations Other Solvent Products Regulation of Solvent Production Physiology of Control of Solvent Formation Genetics of Solvent Formation Is Solvent Production a Cellular Stress Response? Development of New Solvent-Producing Strains The Product Tolerance Problem Biology of Substrate Utilization Metabolic Pathway Inactivation and Amplification Acknowledgment References Keywords: biochemistry; clostridium; clostridium genetics; physiology; solvent fermentations; solvent production; strain development
A review of research and methods for producing high-consequence software

The development of software for use in high-consequence systems mandates rigorous (formal) processes, methods, and techniques to improve the safety characteristics of those systems. This paper provides a brief overview of current research and practices in high-consequence software, including applied design methods. Some of the practices that are discussed include: fault tree analysis, failure mode effects analysis, Petri nets, both hardware and software interlocks, n-version programming, independent vulnerability analyses, and watchdogs. Techniques that offer improvement in the dependability of software in high-consequence systems applications are identified and discussed. Limitations of these techniques are also explored. Research in formal methods, the cleanroom process, and reliability models are reviewed. In addition, current work by several leading researchers as well as approaches being used by leading practitioners are examined. >
Virtual view networks for object reconstruction

All that structure from motion algorithms “see” are sets of 2D points. We show that these impoverished views of the world can be faked for the purpose of reconstructing objects in challenging settings, such as from a single image, or from a few ones far apart, by recognizing the object and getting help from a collection of images of other objects from the same class. We synthesize virtual views by computing geodesics on networks connecting objects with similar viewpoints, and introduce techniques to increase the specificity and robustness of factorization-based object reconstruction in this setting. We report accurate object shape reconstruction from a single image on challenging PASCAL VOC data, which suggests that the current domain of applications of rigid structure-from-motion techniques may be significantly extended.
Exciton-photon coupling in organic materials with large intersystem crossing rates and strong excited state molecular relaxation

We examine the influence of singlet-triplet intersystem crossing and excited state relaxation on exciton-photon coupling in small molecule organic optical microcavities. Both processes quench coupling under non-resonant excitation, allowing estimations of their relative transition rates.
All in the family : state capture in Tunisia

This paper examines the relationship between entry regulation and the business interests of former President Ben Ali's family using firm-level data from Tunisia. Connected firms account for a disproportionate share of aggregate employment, output and profits, especially in sectors subject to authorization and restrictions on FDI. Quantile regressions show that profit and market share premia from being connected increase along the firm-size distribution, especially in highly regulated sectors. These patterns are partly explained by Ben Ali's relatives sorting into the most profitable sectors. The market shares of connected firms are positively correlated with exit and concentration rates in highly regulated sectors. Although causality is difficult to establish, the results are consistent with the hypothesis that the Ben Ali clan abused entry regulation for private gain at the expense of reduced competition.
Tax evasion, corruption, and the remuneration of heterogeneous inspectors

The author develops a general model for addressing the question of how to compensate tax inspectors in an economy where corruption is pervasive - a model that considers the existence of strategic transmission of information. Most of the literature on corruption assumes that the taxpayer and the tax inspector jointly decide on the income to report, which also determines the size of the bribe. In contrast, this model considers the more realistic case in which the taxpayer unilaterally chooses the income to report. The tax inspector cannot change the report and is faced with a binary choice: either he negotiates the bribe on the basis of the income report or he denounces the tax evader and therefore renounces the bribe. In his model, the optimal compensation scheme must take into account the strategic interaction between taxpayers and tax inspectors: a) Pure"tax farming"(paying tax inspectors a share of their tax collections) is optimal only when all tax inspectors are corruptible. b) When there are both honest and corruptible inspectors, the optimal compensation scheme lies between pure tax farming and a pure wage scheme. c) Paradoxically, when inspectors are hired beforehand, it may be optimal to offer contracts that attract corruptible inspectors but not honest ones.
Local distribution and the symmetry gap: approximability of multiway partitioning problems

We study the approximability of multiway partitioning problems, examples of which include Multiway Cut, Node-weighted Multiway Cut, and Hypergraph Multiway Cut. We investigate these problems from the point of view of two possible generalizations: as Min-CSPs, and as Submodular Multiway Partition problems. These two generalizations lead to two natural relaxations that we call respectively the Local Distribution LP, and the Lovasz relaxation. The Local Distribution LP is generally stronger than the Lovasz relaxation, but applicable only to Min-CSP with predicates of constant size. The relaxations coincide in some cases such as Multiway Cut where they are both equivalent to the CKR relaxation.We show that the Lovasz relaxation gives a (2--2/k)-approximation for Submodular Multiway Partition with k terminals, improving a recent 2-approximation [2]. We prove that this factor is optimal in two senses: (1) A (2--2/k -- e)-approximation for Submodular Multiway Partition with k terminals would require exponentially many value queries (in the oracle model), or imply NP = RP (for certain explicit submodular functions). (2) For Hypergraph Multiway Cut and Node-weighted Multiway Cut with k terminals, both special cases of Submodular Multiway Partition, we prove that a (2--2/k -- e)-approximation is NP-hard, assuming the Unique Games Conjecture.Both our hardness results are more general: (1) We show that the notion of symmetry gap, previously used for submodular maximization problems [19, 6], also implies hardness results for submodular minimization problems. (2) Assuming the Unique Games Conjecture, we show that the Local Distribution LP gives an optimal approximation for every Min-CSP that includes the Not-Equal predicate.Finally, we connect the two hardness techniques by proving that the integrality gap of the Local Distribution LP coincides with the symmetry gap of the multilinear relaxation (for a related instance). This shows that the appearance of the same hardness threshold for a Min-CSP and the related submodular minimization problem is not a coincidence.
Ocular pressure in experimental cross-circulation a preliminary report

It has been observed since at least 1924 that the ocular pressure of one eye may be influenced by alterations in the pressure of the second eye. 1 The phrase "ophthalmotonic consensual reaction" has been used to describe this phenomenon. 1 The reaction has been studied in both humans and animals 2-4 and was recently characterized in some detail by Prijot and Stone, 5 who showed that in rabbits compression of one eye could elicit a fall in ocular pressure in the second, undisturbed, eye. This reduction was related to a decrease in aqueous flow while the facility of outflow remained relatively constant. The observation that systematically administered atropine blocked the consensual ophthalmotonic reaction suggested that the reaction was mediated, at least in part, by the autonomic nervous system. Prijot and Stone 5 observed that the maximum effect of flow reduction upon ocular pressure occurred between 15 and 20 minutes
Induced-gravity inflation and the density perturbation spectrum

Abstract Recent experimental determinations of the spectral index describing the scalar mode spectrum of density perturbations encourage comparison with predictions from models of the very early universe. Unlike extended inflation, Induced-gravity Inflation predicts a power spectrum with 0.98 ≤ n s ≤ 1.00, in close agreement with the experimental experimental measurements.
Modeling of nonlinear discrete-time systems from input-output data

Abstract An algorithm is presented that produces a polynomial state affine model for a discrete-time nonlinear system. The method uses only input-output information and is based on a difference equation approximation to the input-output map. From the difference equation, a behaviour matrix is constructed, to be used in the state affine realization algorithm. The difference equation approach requires the estimation of fewer parameters than the usual Volterra series. A state space model is then obtained directly from the difference equation. As a byproduct, a method for calculating the Volterra series directly from the difference equation is obtained. Practical applications to nonlinear systems are included.
Radionuclide Sensors for Environmental Monitoring: From Flow Injection Solid-Phase Absorptiometry to Equilibration-Based Preconcentrating Minicolumn Sensors with Radiometric Detection

The development of in situ sensors for ultratrace detection applications in process control and environmental monitoring remains a significant challenge. Such sensors must meet difficult detection limit requirements while selectively detecting the analyte of interest in complex or otherwise challenging sample matrixes. Nowhere are these requirements more daunting than in the field of radionuclide sensing. The detection limit requirements can be extremely low. Nevertheless, a promising approach to radionuclide sensing based on preconcentrating minicolumn sensors has been developed. In addition, a method of operating such sensors, which we call equilibration-based sensing, has been developed that provides substantial preconcentration and a signal that is proportional to analyte concentration, while eliminating the need for reagents to regenerate the sorbent medium following each measurement. While this equilibration-based sensing method was developed for radionuclide sensing, it can be applied to nonradioactive species as well, given a suitable on-column detection system. By replacing costly sampling and laboratory analysis procedures, in situ sensors could have a significant impact on monitoring and long term stewardship applications. The aim of this review is to cover radionuclide sensors that combine some form of selective sorption with a radiometric detection method, and­as a primary aim­to comprehensively review preconcentrating minicolumn sensorsmore » for radionuclide detection. As a secondary aim, we will cover radionuclide sensors that combine sorption and scintillation in formats other than minicolumn sensors. We are particularly concerned with the detection of alpha- and beta-emitting radionuclides, which present particular challenges for measurements in liquid media.« less
Using Semantic Web technology to support icd-11 textual definitions authoring.

The beta phase of the 11th revision of International Classification of Diseases (ICD-11) intends to accept public input through a distributed model of authoring. One of the core use cases is to create textual definitions for the ICD categories. The objective of the present study is to design, develop, and evaluate approaches to support ICD-11 textual definitions authoring using Semantic Web technology. We investigated a number of heterogeneous resources related to the definitions of diseases, including the linked open data (LOD) from DBpedia, the textual definitions from the Unified Medical Language System (UMLS) and the formal definitions of the Systematized Nomenclature of Medicine—Clinical Terms (SNOMED CT). We integrated them in a Semantic Web framework (i.e., the Linked Data in a Resource Description Framework [RDF] triple store), which is being proposed as a backend in a prototype platform for collaborative authoring of ICD-11 beta. We performed a preliminary evaluation on the usefulness of our approaches and discussed the potential challenges from both technical and clinical perspectives.
A characteristic function approach to the biased sampling model, with application to robust logistic regression

Abstract Many sampling problems from multiple populations can be considered under the semiparametric framework of the biased, or weighted, sampling model. Included under this framework is logistic regression under case–control sampling. For any model, atypical observations can greatly influence the maximum likelihood estimate of the parameters. Several robust alternatives have been proposed for the special case of logistic regression. However, some current techniques can exhibit poor behavior in many common situations. In this paper a new family of procedures are constructed to estimate the parameters in the semiparametric biased sampling model. The procedures incorporate a minimum distance approach, but are instead based on characteristic functions. The estimators can also be represented as the minimizers of quadratic forms in simple residuals, thus yielding straightforward computation. For the case of logistic regression, the resulting estimators are shown to be competitive with the existing robust approaches in terms of both robustness and efficiency, while maintaining affine equivariance. The approach is developed under the case–control sampling scheme, yet is shown to be applicable under prospective sampling logistic regression as well.
Parallel switched circuit simulation on networked workstations

A parallel nonlinear switched circuit simulator based on a modified waveform-Newton (WN) algorithm is implemented on a cluster of workstations linked by Ethernet. The secant method is integrated into the WN algorithm to detect efficiently zero-crossings that control switch operations. The program is written in C+ +, taking advantage of object-oriented programming techniques. Interprocessor communication is implemented by TCP/IP, to transmit floating-point numbers in a simple architecture-independent manner. Network tests conducted on the 156 subnet in the Berkeley.EDU domain show that the communication overhead is not very high. Absolute speed-ups of a factor of two have been demonstrated with five workstations for some test cases.
Aeroelastic Shape Optimization of a Flapping Wing

This paper presents the theory and results for the shape and structural optimization of a platelike flapping wing. The aeroelastic system is analyzed by coupling an unsteady vortex lattice aerodynamics model with a plate finite element model. The assumptions in the aerodynamic model allow the system of equations to be calculated with the inversion of a single matrix, greatly reducing the computational cost. The design variables are the shape parameters from the modified Zimmerman method and the polynomial coefficients that describe the wing thickness. The wing shape and structure are optimized using two multiobjective optimization formulations. The first optimization minimizes the input power while maximizing the cycle-averaged thrust. The input power is the secondary objective function and is treated as a nonlinear constraint, whereas the cycle-averaged thrust is the primary objective function. A second multiobjective formulation that treats wing mass as the secondary objective function is also performed...
An Epicenter Study of the Underground Nuclear Explosion Long Shot

P wave arrival times from the Long Shot underground nuclear explosion are used to systematically study its hypocenter and origin time. Azimuthal variations are shown to exist. If observations in the range 0°≤Δ≤30° are excluded in the analysis, the epicenter location is strongly biased. The adopted epicenter is 17km NW using 0°≤Δ≤105° observations. The solutions using observations in the ranges 0°≤Δ≤25° and 0°≤Δ≤35° are 11 and 9 km, respectively.
CONNECTION BETWEEN ENERGY-DEPENDENT LAGS AND PEAK LUMINOSITY IN GAMMA-RAY BURSTS

We suggest a connection between the pulse paradigm at gamma-ray energies and the recently demonstrated luminosity distribution in gamma-ray bursts: The spectral evolution timescale of pulse structures is anticorrelated with peak luminosity and with quantities that might be expected to reflect the bulk relativistic Lorentz factor, such as spectral hardness ratio. We establish this relationship in two important burst samples using the cross-correlation lags between low (25-50 keV) and high (100-300 keV and >300 keV) energy bands. For a set of seven bursts (six with redshifts) observed by CGRO/BATSE and BeppoSAX that also have optical or radio counterparts, the γ/X peak flux ratios and peak luminosities are anticorrelated with spectral lag. For the 174 brightest BATSE bursts with durations longer than 2 s and significant emission above 300 keV, a similar anticorrelation is evident between gamma-ray hardness ratio or peak flux and spectral lag. For the six bursts with redshifts, the connection between peak luminosity and spectral lag is well fitted by a power law, L53 ≈ 1.3 × (τ/0.01 s)-1.15. While GRB 980425 (if associated with SN 1998bw) would appear to extend this trend qualitatively, with a lag of ~4-5 s and luminosity of ~1.3 × 1047 ergs s-1 , it falls below the power-law relationship by a factor of several hundred. As noted previously by Band, most lags are concentrated on the short end of the lag distribution, near 100 ms, suggesting that the gamma-ray burst luminosity distribution is peaked on its high end.
Aerodynamic properties of fractal grains: Implications for the primordial solar nebula

Gas-grain and grain-grain interactions have a significant role in the evolution of the primordial solar nebula. There is also compelling evidence for larger grains in dense interstellar clouds than in the diffuse interstellar medium. In the usual treatments of grain collisions, where it is assumed that collisions produce compact bodies with a constant density, the gas drag decreases rapidly with size. The first step toward a quantitative analysis of the aerodynamic behavior of fractal aggregates is reported here, and it is shown that for fractals drag decreases very slowly.
Aziridinyl Vinyl Ketones from the Asymmetric Catalytic Aziridination Reaction

Under the aegis of boron Lewis acids, prepared from either the vanol or vapol ligand, vinyl aziridinyl ketones can be obtained with a high degree of asymmetric induction from the catalytic asymmetric aziridination reaction (AZ) of imines and vinyl diazomethyl ketones. The products have potential as synthons for five-carbon chiral amines. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Spin and the Thermal Equilibrium Distribution of Wave Functions

Consider a quantum system S weakly interacting with a very large but finite system B called the heat bath, and suppose that the composite S∪B is in a pure state Ψ with participating energies between E and E+δ with small δ. Then, it is known that for most Ψ the reduced density matrix of S is (approximately) equal to the canonical density matrix. That is, the reduced density matrix is universal in the sense that it depends only on S’s Hamiltonian and the temperature but not on B’s Hamiltonian, on the interaction Hamiltonian, or on the details of Ψ. It has also been pointed out that S can also be attributed a random wave function ψ whose probability distribution is universal in the same sense. This distribution is known as the “Scrooge measure” or “Gaussian adjusted projected (GAP) measure”; we regard it as the thermal equilibrium distribution of wave functions. The relevant concept of the wave function of a subsystem is known as the “conditional wave function.” In this paper, we develop analogous considerations for particles with spin. One can either use some kind of conditional wave function or, more naturally, the “conditional density matrix,” which is in general different from the reduced density matrix. We ask what the thermal equilibrium distribution of the conditional density matrix is, and find the answer that for most Ψ the conditional density matrix is (approximately) deterministic, in fact (approximately) equal to the canonical density matrix.
Application of pressure and temperature sensitive paints for study of heat transfer to a circular impinging air jet

Experimental and computational studies are performed to study pressure and temperature distributions and flow patterns on impingement target surface subject to a single impinging air jet from a plenum. The experiments cover a range of jet-to-target plate distance, Z/D, from 1.5 to 12 for Reynolds number range from 10 000 to 60 000. The main objective is to investigate the optimal jet-to-target distance (Z/D) for stagnation point heat transfer and location of second peak in local heat transfer at small Z/D value under the current jet impingement configuration. Pressure and temperature sensitive paints measurements techniques are implemented to obtain the distribution of pressure and temperature on target surface. The optimal separation distance (Z/D) for stagnation region Nu is found to be about 5. The location of the second peak in local Nu for Z/D of 1.5 is at radial location (r/D) of about 1.8. The area averaged Nusselt numbers are compared to those calculated using correlation from open literature. The agreement varies with Z/D and jet Reynolds number. Experimental results are also compared to computational (CFD) prediction using realizable k–e turbulence model.
Congenital optic disk anomalies

Over the past decade, a wealth of information has accumulated pertaining to the diagnosis and management of patients with congenital optic disk anomalies. As new examples of each entity have been detailed, the diagnostic criteria for each anomaly have become more clearly defined. The advent of sophisticated noninvasive neuroimaging techniques has further refined our ability to accurately detect and categorize the associated CNS anomalies that complicate many of these conditions. In light of recent findings, this review will critically examine many of the well-entrenched concepts pertaining to the diagnosis, evaluation, and treatment of patients with congenital optic disk anomalies. In so doing, it will attempt to dispel some longstanding misconceptions that pervade the literature and obscure our understanding of the pathogenesis, neuroradiological associations, and systemic implications of each anomaly.
Formation of Earth-like Planets During and After Giant Planet Migration

Close-in giant planets are thought to have formed in the cold outer regions of planetary systems and migrated inward, passing through the orbital parameter space occupied by the terrestrial planets in our own solar system. We present dynamical simulations of the effects of a migrating giant planet on a disk of protoplanetary material and the subsequent evolution of the planetary system. We numerically investigate the dynamics of postmigration planetary systems over 200 million years using models with a single migrating giant planet, one migrating and one nonmigrating giant planet, and excluding the effects of a gas disk. Material that is shepherded in front of the migrating giant planet by moving mean motion resonances accretes into hot Earths, but survival of these bodies is strongly dependent on dynamical damping. Furthermore, a significant amount of material scattered outward by the giant planet survives in highly excited orbits; the orbits of these scattered bodies are then damped by gas drag and dynamical friction over the remaining accretion time. In all simulations Earth-mass planets accrete on approximately 100 Myr timescales, often with orbits in the habitable zone. These planets range in mass and water content, with both quantities increasing with the presence of a gas disk and decreasing with the presence of an outer giant planet. We use scaling arguments and previous results to derive a simple recipe that constrains which giant planet systems are able to form and harbor Earth-like planets in the habitable zone, demonstrating that roughly one-third of the known planetary systems are potentially habitable.
A TWO-STAGE DECISION APPROACH TO THE SELECTION PROBLEM

A mathematical solution to the two-stage selection problem was developed which only requires predictor criterion intercorrelations and selection ratio information. Cutting scores on the first stage test are so determined that some individuals are (a) accepted after the first stage, (b) rejected after the first stage, (c) decision withheld, i.e. the decision to accept or reject is postponed until the second stage. The upper and lower cutting scores from stage one, z1″ and z1′ respectively, and the cutting score at the second stage z2.1, where z2.1 = F (z1), and z1’ ≤ z1 ≤ z1” are located such that the expected value on the criterion for accepted applicants is maximized subject to two constraints. The two constraints are the selection ratio and a function of the independent contribution of the second-stage test. Theoretical solutions developed on the computer suggest that a considerable amount of testing time may be saved with little or no decrease in the validity of the selection procedure for all values of the selection ratios.
Relative Option Prices and Risk-Neutral Skew as Predictors of Index Returns

Much real-world research on options has focused on the Black–Scholes implied volatility smile/skew. What causes it? How does it behave? What information does it contain, and can it be used somehow to predict future returns on the underlying asset? Some evidence in the literature suggests that the skew contains a small amount of information about future returns, with a positive skew being a weak signal that the asset’s price will rise the next day. In this article, Ratcliff explores whether and how returns respond to the behavior of the skew, as measured by the implied volatility (IV) difference between an out-of-the-money (OTM) call and an OTM put with the same degree of moneyness.
Feasibility of a full-scale degrader for antimisting kerosene

Experiments are described which demonstrate the feasibility of degrading antimisting kerosene (AMK) in a single pass with a system consisting of an axial piston pump from a TF30 engine and a needle valve The per formance of the degraded AMK was evaluated with full scale aircraft filters (JT8D and CF6), a T63 combustor and laboratory scale tests for filtration and mist ignition At room temperature and higher it was found that AMK could be degraded to perform like Jet A in a single pass with modest power expenditure However, at low temperatures the power requirement increases substantially
Hydrothermal systems on Europa

[1] We estimate the global hydrothermal heat transport on Europa by considering the range of heat generation resulting from tidal stresses and radiogenic heat production within Europa's rocky sub-ocean lithosphere. We show that if factors controlling tidally generated heat on Europa are similar to those on Io, global hydrothermal heat output and its high-temperature component may exceed that on Earth. On the individual system scale, however, the low acceleration of gravity on Europa indicates that individual hydrothermal plumes are relatively weak. Such weak hydrothermal plumes are not likely to result in melt through events, which have been hypothesized to form surface features such as Conamara Chaos. Studies of concentrated hydrothermal activity and the resulting interacting plumes are needed to address the possible impact of hydrothermal activity on Europa's ice sheet.
Elastodynamic Near-Tip Stress and Displacement Fields for Rapidly Propagating Cracks in Orthotropic Materials

The near-tip angular variations of elastodynamic stress and displacement fields are investigated for rapid transient crack propagation in isotropic and orthotropic materials. The 2-dimensional near-tip displacement fields are assumed in the general form r/sup P/ T(t, c) K(theta, c), where c is a time-varying velocity of crack propagation, and it is shown that p = 0.5. For isotropic materials, K(theta, c) is determined explicitly by analytical considerations. A numerical procedure is employed to determine K(theta, c) for orthotropic materials. The tendency of the maximum stresses to move out of the plane of crack propagation as the speed of crack propagation increases is more pronounced for orthotropic materials, for the case that the crack propagates in the direction of the larger elastic modulus. The angular variations of the near-tip fields are the same for steady-state and transient crack propagation, and for propagation along straight and curved paths, provided that the direction of crack propagation and the speed of the crack tip vary continuously.
Metastability of a Supercompressed Fluid Monolayer

Previous studies showed that monomolecular films of extracted calf surfactant collapse at the equilibrium spreading pressure during quasi-static compressions but become metastable at much higher surface pressures when compressed faster than a threshold rate. To determine the mechanism by which the films become metastable, we studied single-component films of 1-palmitoyl-2-oleoyl phosphatidylcholine (POPC). Initial experiments confirmed similar metastability of POPC if compressed above a threshold rate. Measurements at different surface pressures then showed that rates of collapse, although initially increasing above the equilibrium spreading pressure, reached a sharply defined maximum and then slowed considerably. When heated, rapidly compressed films recovered their ability to collapse with no discontinuous change in area, arguing that the metastability does not reflect transition of the POPC film to a new phase. These observations indicate that in several respects, the supercompression of POPC monolayers resembles the supercooling of three-dimensional liquids toward a glass transition.
Dynamic interaction among price, quality, durability and the sales rate in a steady state environment: A theoretical analysis

This paper investigates the relationship among price, quality, product durability, quality durability and the sales rate for durable goods. The research builds on a dynamic model of sales reponse, developed by Narasimhan et al. [R. Narasimhan, S. Ghosh, D. Mendez, A dynamic model of product quality and pricing decisions on sales response, Decision Sciences 24 (5) (1993) 893-908]. First, the paper determines whether a stable relationship among price, quality, product durability, quality durability and the sales rate exists, by examining the equilibrium properties of the model. Second, the paper uses the derived equilibrium expressions to develop insights into the relationship among these variables. Third, the paper examines the necessary conditions for the price equilibrium level to be optimal, from the point of view of a profit-maximizing producer. Finally, the paper employs a graphical analysis technique to investigate the impact of increases in quality and quality durability on the optimum price level. Among many results, the paper shows the existence of a minimum quality level and a maximum price level for the sales rate to remain positive. The research also shows that an increase in quality durability (stemming, for instance, from increased advertising) commands an increase in price regardless of the product's price elasticity of demand. Additionally, the paper establishes an explicit relationship between quality improvements and optimal prices. The practical relevance of the findings is discussed.
Reliability-based design optimization of aeroelastic structures

Aeroelastic phenomena are most often either ignored or roughly approximated when uncertainties are considered in the design optimization process of structures subject to aerodynamic loading, affecting the quality of the optimization results. Therefore, a design methodology is proposed that combines reliability-based design optimization and high-fidelity aeroelastic simulations for the analysis and design of aeroelastic structures. To account for uncertainties in design and operating conditions, a first-order reliability method (FORM) is employed to approximate the system reliability. To limit model uncertainties while accounting for the effects of given uncertainties, a high-fidelity nonlinear aeroelastic simulation method is used. The structure is modelled by a finite element method, and the aerodynamic loads are predicted by a finite volume discretization of a nonlinear Euler flow. The usefulness of the employed reliability analysis in both describing the effects of uncertainties on a particular design and as a design tool in the optimization process is illustrated. Though computationally more expensive than a deterministic optimum, due to the necessity of solving additional optimization problems for reliability analysis within each step of the broader design optimization procedure, a reliability-based optimum is shown to be an improved design. Conventional deterministic aeroelastic tailoring, which exploits the aeroelastic nature of the structure to enhance performance, is shown to often produce designs that are sensitive to variations in system or operational parameters.