cssi/SciSciGPT-SciSciNet huggingface dataset:
The Magnification Invariant of Simple Galaxy Lens Models

We demonstrate that for several of the gravitational lens models used to describe galaxies, there exists a quantity we dub the magnification invariant, equaling the sum of the signed magnifications of the images, that is a constant when the image multiplicity is a maximum. This invariant is independent of most of the model parameters, and it is independent of the source position as long as the source lies inside the caustic. It is not necessary to solve the lens equations in order to compute this invariant. For quadruple lenses, it is usually easy to assign image parities, and thus one can compute the sum of the signed fluxes, compare it with the magnification invariant of different models, and infer the model magnification factors of the images without fitting. We evaluate the invariant for simple galaxy models, apply it to known cases of quadruple lenses, and discuss implications for the ability of these lens models to reproduce observed image brightnesses.
Sphere packings, I

We describe a program to prove the Kepler conjecture on sphere packings. We then carry out the first step of this program. Each packing determines a decomposition of space into Delaunay simplices, which are grouped together into finite configurations called Delaunay stars. A score, which is related to the density of packings, is assigned to each Delaunay star. We conjecture that the score of every Delaunay star is at most the score of the stars in the face-centered cubic and hexagonal close packings. This conjecture implies the Kepler conjecture. To complete the first step of the program, we show that every Delaunay star that satisfies a certain regularity condition satisfies the conjecture.
Where is everybody

In our Galaxy we expect about 109 habitable planets, similar to our Earth but mostly a few 109 years older. If we generalize our own case and present state, we should try by all means to take up radio contact with the other civilizations. But if we generalize our probable future technical activities, the Galaxy should be teeming with life, of which we have seen no sign so far, and all habitable planets including Earth should have been colonized long ago by others, which certainly is not the case. This is considered a severe puzzle: it seems difficult to avoid the conclusion of our uniqueness, but even more difficult to accept and explain it.
Pollution Abatement Costs and Foreign Direct Investment Inflows to U.S. States: A Nonparametric Reassessment

Abstract Keller and Levinson (2002) utilize state-level panel data on inflows of foreign direct investment along with an innovative measure of relative pollution abatement costs to assess the impact of environmental stringency on capital flows. Using standard parametric panel data models, the authors find moderate evidence that capital flows are sensitive to abatement costs. Using recently developed nonparametric methods, we assess the robustness of this conclusion. The nonparametric approach reveals that (a) some of the parametric results are not robust, and (b) the impact of relative abatement costs is heterogeneous across states and generally of smaller magnitude than previously suggested.
Identifying causal variants at loci with multiple signals of association.

Although genome-wide association studies have successfully identified thousands of risk loci for complex traits, only a handful of the biologically causal variants, responsible for association at these loci, have been successfully identified. Current statistical methods for identifying causal variants at risk loci either use the strength of the association signal in an iterative conditioning framework or estimate probabilities for variants to be causal. A main drawback of existing methods is that they rely on the simplifying assumption of a single causal variant at each risk locus, which is typically invalid at many risk loci. In this work, we propose a new statistical framework that allows for the possibility of an arbitrary number of causal variants when estimating the posterior probability of a variant being causal. A direct benefit of our approach is that we predict a set of variants for each locus that under reasonable assumptions will contain all of the true causal variants with a high confidence level (e.g., 95%) even when the locus contains multiple causal variants. We use simulations to show that our approach provides 20–50% improvement in our ability to identify the causal variants compared to the existing methods at loci harboring multiple causal variants. We validate our approach using empirical data from an expression QTL study of CHI3L2 to identify new causal variants that affect gene expression at this locus. CAVIAR is publicly available online at http://genetics.cs.ucla.edu/caviar/.
Catalytic, enantioselective acetate aldol additions to α,β-ynals: Preparation of optically active propargylic alcohols

Abstract A catalytic, enantioselective acetate-aldol addition reaction of silyl ketene acetals with α,β-ynals and 3 mol % of a chiral Ti(IV) complex is described. This process provides access to optically active β-hydroxy-γ-alkynyl esters in 84–96% yields and 94–97% ee's.
Physically based volumetric efficiency model for diesel engines utilizing variable intake valve actuation

Advanced diesel engine architectures employing flexible valve trains enable emissions reductions and fuel economy improvements. Flexibility in the valve train allows engine designers to optimize th...
Electrical conductances of aqueous Na2SO4, H2SO4, and their mixtures: limiting equivalent ion conductances, dissociation constants, and speciation to 673 K and 28 MPa.

The electrical conductivities of aqueous solutions of Na2SO4, H2SO4, and their mixtures have been measured at 373−673 K at 12−28 MPa in dilute solutions for molalities up to 10-2 mol kg-1. These conductivities have been fit to the conductance equation of Turq et al.1 with a consensus mixing rule and mean spherical approximation activity coefficients. Provided the concentration is not too high, all of the data can be fitted by a solution model that includes ion association to form NaSO4-, Na2SO40, HSO4-, H2SO40, and NaHSO40. The adjustable parameters of this model are the dissociation constants of the SO4- species and the H+, SO4-2, and HSO4- conductances (ion mobilities) at infinite dilution. For the 673 K and 230 kg m-3 state point with the lowest dielectric constant, e = 3.5, where the Coulomb interactions are the strongest, this model does not fit the experimental data above a solution molality of 0.016. Including the species H9(SO4)5- gave satisfactory fits to the conductance data at the higher concen...
The role of accounting and auditing in corporate governance and the development of financial markets around the world

Abstract For a sample of 31 countries, we document that financial disclosures are more transparent and national accounting standards require timelier (accrual based) reporting in countries with stronger investor protection. These countries also spend more on auditing enforcement and the Big Five accounting firms audit proportionately more companies in these countries. These results indicate that higher quality accounting standards and the enforcement of such standards through higher quality auditing are more likely to exist in corporate governance in countries with strong investor protection. Higher quality accounting and auditing are also positively associated with financial market development in countries whose legal systems are conducive to the protection of investors. However, we are unable to find systematic evidence that higher quality accounting and auditing alone—independent of a country's underlying investor protection regime—affects the development of financial markets. © City University of Hong...
Using local optimality criteria for efficient information retrieval with redundant information filters

We consider information retrieval when the data—for instance, multimedia—is computationally expensive to fetch. Our approach uses “information filters” to considerably narrow the universe of possibilities before retrieval. We are especially interested in redundant information filters that save time over more general but more costly filters. Efficient retrieval requires that decisions must be made about the necessity, order, and concurrent processing of proposed filters (an “execution plan”). We develop simple polynomial-time local criteria for optimal execution plans and show that most forms of concurrency are suboptimal with information filters. Although the general problem of finding an optimal execution plan is likely to be exponential in the number of filters, we show experimentally that our local optimality criteria, used in a polynomial-time algorithm, nearly always find the global optimum with 15 filters or less, a sufficient number of filters for most applications. Our methods require no special hardware and avoid the high processor idleness that is characteristic of massive-parallelism solutions to this problem. We apply our ideas to an important application, information retrieval of captioned data using natural-language understanding, a problem for which the natural-language processing can be the bottleneck if not implemented well.
Progress and Challenges in Electronic Health Record Adoption: Findings From a National Survey of Physicians

One in 10 physicians has no plans to adopt an electronic health record. These physicians were older; in small, isolated practices; and were not participating in other delivery system or payment reform efforts.
Direct determination of DNA twist-stretch coupling

The symmetries of the DNA double helix require a new term in its linear response to stress: the coupling between twist and stretch. Recent experiments with torsionally constrained single molecules give the first direct measurement of this important material parameter. We extract its value from a recent experiment of Strick et al. (Science, 271 (1996) 1835) and find agreement with an independent experimental estimate recently given by Marko. We also present a very simple microscopic theory predicting a value comparable to the one observed.
Comprehensive analysis of two downburst-related aircraft accidents

Although downbursts have been identified as the major cause of a number of aircraft takeoff and landing accidents, only the 1985 Dallas/Fort Worth (DFW) and the more recent (July 1994) Charlotte, North Carolina, landing accidents provided sufficient onboard recorded data to perform a comprehensive analysis of the downburst phenomenon. The first step in the present analysis was the determination of the downburst wind components. Once the wind components and their gradients were determined, the degrading effect of the wind environment on the airplane's performance was calculated. This wind-shear-induced aircraft performance degradation, sometimes called the F-factor, was broken down into two components F(sub 1) and F(sub 2), representing the effect of the horizontal wind gradient and the vertical wind velocity, respectively. In both the DFW and Charlotte cases, F(sub 1) was found to be the dominant causal factor of the accident. Next, the aircraft in the two cases were mathematically modeled using the longitudinal equations of motion and the appropriate aerodynamic parameters. Based on the aircraft model and the determined winds, the aircraft response to the recorded pilot inputs showed good agreement with the onboard recordings. Finally, various landing abort strategies were studied. It was concluded that the most acceptable landing abort strategy from both an analytical and pilot's standpoint was to hold constant nose-up pitch attitude while operating at maximum engine thrust.
Model order effects on the transmission zeros of flexible space structures

This paper proves that the transmission zeros of finite-dimensional models for a flexible structure exhibit precisely the same Rayleigh-Ritz convergence properties as do the poles of such models.
Aerosol administration of antibiotics

Aerosol administration of antibiotics is an attractive approach to the treatment of the recurrent respiratory infections experienced by patients suffering from cystic fibrosis (CF). Through aerosol ad
Platinum(IV)-chlorotoxin (CTX) conjugates for targeting cancer cells

Cisplatin is one of the most widely used anticancer drugs. Its side effects, however, have motivated researchers to search for equally effective analogs that are better tolerated. Selectively targeting cancer tissue is one promising strategy. For this purpose, a platinum(IV) complex was conjugated to the cancer-targeting peptide chlorotoxin (CTX, TM601) in order to deliver cisplatin selectively to cancer cells. The 1:1 Pt-CTX conjugate was characterized by mass spectrometry and gel electrophoresis. Like most platinum(IV) derivatives, the cytotoxicity of the conjugate was lower in cell culture than that of cisplatin, but greater than those of its Pt(IV) precursor and CTX in several cancer cell lines.
Fragmentation function in non-equilibrium QCD using closed-time path integral formalism

In this paper we implement the Schwinger–Keldysh closed-time path integral formalism in non-equilibrium QCD in accordance to the definition of the Collins–Soper fragmentation function. We consider a high-p T parton in QCD medium at initial time τ 0 with an arbitrary non-equilibrium (non-isotropic) distribution function $f(\vec{p})$ fragmenting to a hadron. We formulate the parton-to-hadron fragmentation function in non-equilibrium QCD in the light-cone quantization formalism. It may be possible to include final-state interactions with the medium via a modification of the Wilson lines in this definition of the non-equilibrium fragmentation function. This may be relevant to the study of hadron production from a quark–gluon plasma at RHIC and LHC.
Branes, rings and matrix models in minimal (super)string theory

We study both bosonic and supersymmetric (p,q) minimal models coupled to Liouville theory using the ground ring and the various branes of the theory. From the FZZT brane partition function, there emerges a unified, geometric description of all these theories in terms of an auxiliary Riemann surface p,q and the corresponding matrix model. In terms of this geometric description, both the FZZT and ZZ branes correspond to line integrals of a certain one-form on p,q. Moreover, we argue that there are a finite number of distinct (m,n) ZZ branes, and we show that these ZZ branes are located at the singularities of p,q. Finally, we discuss the possibility that the bosonic and supersymmetric theories with (p,q) odd and relatively prime are identical, as is suggested by the unified treatment of these models.
A High-Speed Erupting-Prominence CME: A Bridge Between Types

Several studies have indicated that there may be two distinct types of coronal mass ejections (CMEs); a high-velocity bright energetic type associated with flares, and a smaller slower less impressive type associated with erupting prominences. How valid is this distinction? We analyze a CME combining attributes of both types, a high-velocity bright CME associated with an erupting prominence. A study of this event and several others allows us to argue that the apparent differences separating the two types may be an observational effect. Our results are consistent with a single CME process for both flare-associated and filament-associated CMEs. This process consists of three stages. The initial stage is brought about by the emergence of new magnetic flux, which interacts with the pre-existing magnetic configuration and results in a slow rise of the magnetic structure, which later becomes the CME. The second stage is a fast reconnection phase with flaring and a sudden increase of the rise velocity of the magnetic structure. It also includes a rapidly increasing CME acceleration followed by a rapidly falling acceleration. The third stage or CME propagation stage shows only slow changes in the acceleration and finally the velocity becomes constant. LASCO observes only the third stage. The differences found between observed flare-associated and prominence-associated CME velocity behavior appear to be primarily due to the relative heights in the corona at which the erupting structures form.
Qubit degradation due to cross-phase modulation photon-number measurement

The error probability of quantum nondemolition detection of a vacuum/one-photon qubit is shown to increase from 0 to 1/2 as the post-interaction fidelity increases from 2/3 to 1.
Analysis of an RNG based turbulence model for separated flows

A two-equation turbulence model of the K-epsilon type was recently derived by using Renormalization Group (RNG) methods. It was later reported that this RNG based model yields substantially better predictions than the standard K-epsilon model for turbulent flow over a backward facing step - a standard test case used to benchmark the performance of turbulence models in separated flows. The improvements obtained from the RNG K-epsilon model were attributed to the better treatment of near wall turbulence effects. In contrast to these earlier claims, it is shown in this paper that the original version of the RNG K-epsilon model substantially underpredicts the reattachment point in the backstep problem. This is a deficiency that is traced to the modeling of the production of dissipation term. However, with the most recent improvements in the RNG K-epsilon model, excellent results for the backstep problem are now obtained.
Frequency-coded waveforms for enhanced delay-Doppler resolution

In this paper, we propose techniques for the construction of frequency-coding sequences that give rise to frequency-coded waveforms having ambiguity functions with a clear area - containing no sidelobes - in a connected region surrounding the main lobe. These constructed sequences are called pushing sequences. First, two important properties of pushing sequences are investigated: the group D/sub 4/ dihedral symmetry property and the frequency omission property. Using the group D/sub 4/ dihedral symmetry property, we show how to construct additional pushing sequences from a given pushing sequence. Using the frequency omission property, we show how to construct pushing sequences of any length N and design proper frequency-coded waveforms that meet specific constraints in the frequency domain. Next, we use the Lempel T/sub 4/ construction of Costas sequences to construct pushing sequences with power 1. Finally, we show how to construct pushing sequences with any desired power using Lee codewords. Because these arbitrary-power pushing sequences constructed using Lee codewords do not have the Costas property, we derive expressions for the pattern of hits in the geometric array. Based on this, the general form of the positions and levels of all the sidelobe peaks are derived.
IRAS observations of Seyfert galaxies

Infrared Astronomy Satellite measurements at 25, 60 and 100 microns were used to analyze the infrared properties of Seyfert galaxies from the Markarian and NGC Catalogs. One hundred and sixteen of 186 Seyfert galaxies were detected. About 50% of all Seyfert galaxies in the sample have 60 micron luminosities in excess of 10 to the 10th power solar luminosity, and the mean 60 micron luminosity increase with the optical B absolute magnitude. The luminosity functions of the Seyfert 1 and Seyfert 2 galaxies appear quite similar. It is possible, however, to statistically separate the two types of galaxies in color-color plots. The 100- to 60- micron energy distributions flatten systematically with increasing 60- micron luminosity. The infrared measurements provide a measure of the bolometric luminosity of the Seyfert galaxies, but do not discriminate between the physical processes involved.
Performance of wind turbines in a turbulent atmosphere

Abstract The effect of atmospheric turbulence on the power fluctuations of large wind turbines is studied. The significance of spatial non-uniformities of the wind is emphasized. The turbulent wind correlation in time and space is simulated on the computer by Shinozukas method. The wind turbulence is modeled according to the Davenport spectrum with an exponential spatial correlation function. The rotor aerodynamics is modeled by simple blade element theory. Comparison of the spectrum of power output signal between 1-D and 3-D turbulence. shows the significant power fluctuations centered around the blade passage frequency.
Optical simulations of skin diagnosis with account of multiple surface scattering events

To fully exploit current optical methods of skin diagnosis, it is desirable to understand the physics underlying photon migration in epithelial tissue. A number of approaches have been developed to meet this challenge. Most simulations are based upon the radiative transport theory which describes the sequential transfer of diffuse light through the stack of skin layers. These models are computationally intensive and typically rely upon the following assumptions: (1) volume scattering of photons inside the collagen fiber layer is predominant, (2) photons undergo Fresnel reflections on each boundary, (3) scattering can be modeled along each path using prescribed phase functions such as Henyey-Greenstein or Mie. Our work simulates photon migration in skin from a different standpoint: using a commercially available optics code, we randomly trace a large number of photons and assign generic absorption and scattering properties to all boundaries, including the ones separating sublayers of collagen fibers. As a result, single and multiple surface scattering events are account for. Absorbing inhomogeneities may be included as light obstructions and fluorophores as secondary sources, respectively. This preliminary work is targeted for clinical applications involving skin imaging and spectroscopy.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Vibrational Relaxation of OH and CH Fundamentals of Polar and Nonpolar Molecules in the Condensed Phase

Studies of vibrational energy flow in various polar and nonpolar molecules that follows the ultrafast excitation of the CH and OH stretch fundamentals, modeled using semiclassical methods, are reviewed. Relaxation rates are calculated using Landau−Teller theory and a time-dependent method, both of which consider a quantum mechanical solute molecule coupled to a classical bath of solvent molecules. A wide range of decay rates are observed, ranging from 1 ps for neat methanol to 50 ps for neat bromoform. In order to understand the flow rates, it is argued that an understanding of the subtle mixing between the solute eigenstates is needed and that solute anharmonicities are critical to facilitating condensed phase vibrational relaxation. The solvent-assisted shifts of the solute vibrational energy levels are seen to play a critical role of enhancing or decreasing lifetimes.
Damage Evolution of Fiber/Mortar Interface During Fiber Pullout

This study aims at connecting the change in interfacial properties of FRC during fiber pullout to the microstructural features of the interface. The interfaces between steel, polypropylene and nylon fibers and mortar are investigated by SEM and EDXA at four stages during fiber pullout (a) before debonding; (b) right after debonding; (c) pullout 1 mm and (d) pullout 10 mm. Since fiber pullout is found to be sensitive to lateral compression, microscopic studies are carried out on fibers pulled out with and without lateral compression. For steel FRC, significant damage occurs at the interfacial transition zone (ITZ) of the mortar. Regardless of the presence or absence of lateral compression, it is found that the “abrasion and grinding effect” is the major mechanism leading to the rapid decline of the pullout force and interfacial friction. Based on SEM and EDXA results, an interfacial damage evolution process is proposed. For polymeric FRC’s, the damage occurs mainly on the polypropylene and nylon fibers and the ITZ of the mortar experiences much less damage. The surface of the polypropylene fiber is shaved and abraded during the pullout process. The surface of the nylon fiber is peeled and shaved which contributes to the increase of the pullout force and interfacial friction.
The Form and Evolution of the Clustering of QSO Heavy-Element Absorption-Line Systems

We have analyzed the clustering of C IV and Mg II absorption-line systems on comoving scales r from 1 to 16 h-1 Mpc, using an extensive catalog of heavy-element QSO absorbers with mean redshift zC IV = 2.2 and zMg II = 0.9. We find that, for the C IV sample as a whole, the absorber line-of-sight correlation function is well fitted by a power law of the form ξaa(r) = (r0/r)γ, with maximum-likelihood values of γ=1.75 -->−0.70+0.50 and comoving r -->0=3.4 -->+ 0.7−1.0 h-1 Mpc (q0 = 0.5). The clustering of absorbers at high redshift is thus of a form that is consistent with that found for galaxies and clusters at low redshift, and of amplitude such that absorbers are correlated on scales of galaxy clusters. We also trace the evolution of the mean amplitude ξ0(z) of the correlation function, as a function of redshift, from z = 3 to z = 0.9. We find that, when parameterized in the conventional manner as ξ0(z) (1 + z)-(3+)+γ, the amplitude grows with decreasing redshift, with a maximum-likelihood value for the evolutionary parameter of = 2.05 ± 1.0 (q0 = 0.5). When extrapolated to zero redshift, the amplitude of the correlation function implies that the correlation length r -->0=30 -->−13+22 h-1 Mpc (q0 = 0.5). This suggests that strong C IV and Mg II absorbers, on megaparsec scales, are biased tracers of the higher density regions of space and that agglomerations of strong absorbers along a line of sight are indicators of clusters and superclusters. This is supported by recent observations of Lyman break galaxies. The growth seen in the clustering of absorbers is consistent with gravitationally induced growth of perturbations.
Selenoxides as Catalysts for the Activation of Hydrogen Peroxide. Bromination of Organic Substrates with Sodium Bromide and Hydrogen Peroxide

Diphenyl selenoxide (7), dibenzyl selenoxide (8), and several aryl benzyl selenoxides (9−13) are catalysts for the bromination of organic substrates in two-phase systems of CH2Cl2 and pH 6 phosphate buffer containing 2.0 M NaBr and 2.6 M H2O2. The catalysts are effective at 2.5 mol % relative to the organic substrates. In the bromination of 4-pentenoic acid, electron-donating substituents in the selenoxides accelerate the reaction, while electron-withdrawing substituents slow the reaction. Benzyl 2-((dimethylamino)methyl)phenyl selenoxide (13), with a chelating dimethylamino group, was the most effective catalyst and was used in the preparative bromination of 4-pentenoic acid, 2,2-diphenyl-4-pentenoic acid, 1,3,5-trimethoxybenzene, N,N-dimethylaniline, and N-phenylmorpholine.
Quantifying Pituitary-Adrenal Dynamics and Deconvolution of Concurrent Cortisol and Adrenocorticotropic Hormone Data by Compressed Sensing

Pulsatile release of cortisol from the adrenal glands is governed by pulsatile release of adrenocorticotropic hormone (ACTH) from the anterior pituitary. In return, cortisol has a negative feedback effect on ACTH release. Simultaneous recording of ACTH and cortisol is not typical, and determining the number, timing, and amplitudes of pulsatile events from simultaneously recorded data is challenging because of several factors: 1) stimulator ACTH pulse activity, 2) kinematics of ACTH and cortisol, 3) the sampling interval, and 4) the measurement error. We model ACTH and cortisol secretion simultaneously using a linear differential equations model with Gaussian errors and sparse pulsatile events as inputs to the model. We propose a novel framework for recovering pulses and parameters underlying the interactions between ACTH and cortisol. We recover the timing and amplitudes of pulses using compressed sensing and employ generalized cross validation for determining the number of pulses. We analyze serum ACTH and cortisol levels sampled at 10-min intervals over 24 h from ten healthy women. We recover physiologically plausible timing and amplitudes for these pulses and model the feedback effect of cortisol. We recover 15 to 18 pulses over 24 h, which is highly consistent with the results of another cortisol data analysis approach. Modeling the interactions between ACTH and cortisol allows for accurate quantification of pulsatile events, and normal and pathological states. This could lay the basis for a more physiologically-based approach for administering cortisol therapeutically. The proposed approach can be adapted to deconvolve other pairs of hormones with similar interactions.
Hyperglycosylated hCG in the management of quiescent and chemorefractory gestational trophoblastic diseases

Abstract Introduction The literature shows that hyperglycosylated hCG is the invasion stimulus in malignant gestational trophoblastic diseases. The USA hCG Reference Service has characterized 2 gestational trophoblastic disease conditions marked by low proportion of hyperglycosylated hCG. These are quiescent gestational trophoblastic disease, defined as inactive or benign invasive disease, and minimally invasive gestational trophoblastic disease, defined as slow growing or chemorefractory disease with hCG increasing very slowly (doubling rate 2–6 weeks). Here we examine the USA hCG Reference Service experience with both diseases. Methods Patient were referred to the USA hCG Reference Service, 133 cases shown to have quiescent gestational trophoblastic disease, 35 cases with aggressive and 30 with minimally invasive gestational trophoblastic disease. Results Quiescent or inactive gestational trophoblastic disease was demonstrated in 133 women. In 127 of these cases, no hyperglycosylated hCG was detected, and in 6 cases 4–27% hyperglycosylated hCG was detected. This is quiescent or inactive disease. Only 1 of 35 cases with aggressive gestational trophoblastic disease (>40% hyperglycosylated hCG) was chemorefractory. In contrast, 30 of 30 minimally invasive cases ( 3000 IU/L before commencing chemotherapy. This was successful in 10 of 10 minimally invasive cases. Discussion Measurement of hyperglycosylated hCG or invasiveness is a critical step in management of invasive gestational trophoblastic disease. Quiescent of inactive gestational trophoblastic disease requires no therapy. Minimally invasive disease in chemorefractory. The USA hCG Reference Service experience suggests waiting until hCG exceeds 3000 IU/L before commencing any chemotherapy.
Faint Infrared Flares from the Microquasar GRS 1915+105.

We present simultaneous infrared and X-ray observations of the Galactic microquasar GRS 1915+105 using the Palomar 5 m telescope and Rossi X-Ray Timing Explorer on 1998 July 10 UT. Over the course of 5 hr, we observed six faint infrared (IR) flares with peak amplitudes of ~0.3-0.6 mJy and durations of ~500-600 s. These flares are associated with X-ray soft-dip/soft-flare cycles, as opposed to the brighter IR flares associated with X-ray hard-dip/soft-flare cycles seen in 1997 August by Eikenberry et al. Interestingly, the IR flares begin before the X-ray oscillations, implying an "outside-in" origin of the IR/X-ray cycle. We also show that the quasi-steady IR excess in 1997 August is due to the pileup of similar faint flares. We discuss the implications of this flaring behavior for understanding jet formation in microquasars.
Dynamic behavior of offshore structures with bilinear stiffness

A single degree-of-freedom model of offshore structures with bilinear stiffness is studied for its dynamic response to a nonzero mean, oscillatory fluid flow. Of particular interest is the interaction between the bilinear stiffness characteristic and the asymmetric hydrodynamic drag force. The shooting method and the incremental harmonic balance method are used to determine the periodic steady state solutions. The stability of these solutions is examined by numerically computing the Floquet multipliers. The stability boundaries are also verified by comparison with the results obtained by direct numerical integration. The cases of stiffness ratio >1 and A large primary resonance, several subharmonic resonances as well as small superharmonic resonances are found to exist. At higher wave frequencies, multiple stable steady state solutions can coexist. The presence of nonzero current gives rise to a significant qualitative change in the response. Hysteresis and asymmetry in the subharmonic solutions appear when the asymmetric drag force is introduced. For stiffness ratios >1, successive period-doubling bifurcations result for some odd-order subharmonic responses. Further increases in the stiffness ratio can result in a “crisis” in that higher-order subharmonics suddenly disappear and for every initial condition, the solutions, after long transients, converge to solutions with the exciting wave frequency. For stiffness ratios
Harnessing the benefits of betrayal aversion

Abstract Recent research suggests that while betrayal aversion may have negative effects, the presence of betrayal-averse agents is beneficial in reducing trustees’ willingness to betray trust. In light of this, many common knowledge institutions may have adopted rules and features which mitigate the emotional disutility associated with betrayal aversion, while simultaneously maintaining the high levels of reciprocation brought about by the presence of betrayal-averse agents. Here we conduct a laboratory experiment that identifies one such feature common to many institutions successfully governing economic and social interaction: the option to avoid knowing painful details of failed economic exchange.
Molecular Rearrangements in the Construction of Complex Molecules

A personal account is given of the development in my laboratory of designed molecular rearrangements and their application in target-directed synthesis.
Specialist Risk Attitudes and the Bid‐Ask Spread

This paper examines the relation between the bid-ask spread and the risk of the underlying stock. It provides evidence that the specialist is not only sensitive to the absolute level of volatility, but also to changes in the level of volatility. This sensitivity arises because of increased inventory risk for the specialist when volatility is changing. For the sample of very liquid stocks in this paper, the quoted spread and the inventory cost component of the spread are shown to increase significantly during trading periods when volatility is both increasing and decreasing.
Rearrangement of 2-amino-4-(trifluoromethyl)oxazoles to hydantoins

Reaction of 2-amino-4-trifluoromethyloxazoles with excess bromine in acetic acid/sodium acetate gives 5-acetoxyhydantoins. The 5-bromooxazoles are intermediates in the reaction.
Regime Shifts in a Dynamic Term Structure Model of U.S. Treasury Bond Yields

This article develops and empirically implements an arbitrage-free, dynamic term structure model with ‘‘priced’’ factor and regime-shift risks. The risk factors are assumed to follow a discrete-time Gaussian process, and regime shifts are governed by a discrete-time Markov process with state-dependent transition probabilities. This model gives closed-form solutions for zero-coupon bond prices, an analytic representation of the likelihood function for bond yields, and a natural decomposition of expected excess returns to components corresponding to regime-shift and factor risks. Using monthly data on U.S. Treasury zero-coupon bond yields, we show a critical role of priced, state-dependent regime-shift risks in capturing the time variations in expected excess returns, and document notable differences in the behaviors of the factor risk component of the expected returns across high and low volatility regimes. Additionally, the state dependence of the regime-switching probabilities is shown to capture an interesting asymmetry in the cyclical behavior of interest rates. The shapes of the term structure of volatility of bond yield changes are also very different across regimes, with the well-known hump being largely a low-volatility regime phenomenon. (JEL G12) This article develops and empirically implements an arbitrage-free, dynamic term structure model (DTSM) with ‘‘priced’’ factor and regimeshift risks. The risk factors are assumed to follow a discrete-time Gaussian process, and regime shifts are governed by a discrete-time Markov process with state-dependent transition probabilities. Agents are assumed to know both the current state of the economy and the regime they are currently in. This leads to regime-dependent risk-neutral pricing and an equilibrium term structure that reflects the risks of both changes in the state and shifts in regimes.
INK JET PROCESSING OF METALLIC NANOPARTICLE SUSPENSIONS FOR ELECTRONIC CIRCUITRY FABRICATION

A solution-processable approach in creating gold circuit electrodes with features as fine as 100 μm is demonstrated, using a piezoelectrically driven printhead to deposit metallic nanoparticle susp...
Eigenvector Localization for Random Band Matrices with Power Law Band Width

It is shown that certain ensembles of random matrices with entries that vanish outside a band around the diagonal satisfy a localization condition on the resolvent which guarantees that eigenvectors have strong overlap with a vanishing fraction of standard basis vectors, provided the band width W raised to a power μ remains smaller than the matrix size N. For a Gaussian band ensemble, with matrix elements given by i.i.d. centered Gaussians within a band of width W, the estimate μ ≤ 8 holds.
Economical experiments: Bayesian efficient experimental design

We propose and implement a Bayesian optimal design procedure. Our procedure takes as its primitives a class of parametric models of strategic behavior, a class of games (experimental designs), and priors on the behavioral parameters. We select the experimental design that maximizes the information from the experiment. We sequentially sample with the given design and models until only one of the models has viable posterior odds. A model which has low posterior odds in a small collection of models will have an even lower posterior odds when compared to a larger class, and hence we can dismiss it. The procedure can be used sequentially by introducing new models and comparing them to the models that survived earlier rounds of experiments. The emphasis is not on running as many experiments as possible, but rather on choosing experimental designs to distinguish between models in the shortest possible time period. We illustrate this procedure with a simple experimental game with one-sided incomplete information.
Exact Inverse Scattering Theory

The concepts of reference wave slowness (reciprocal of velocity) and an associated free reference space Green's function slowness spectrum are introduced. A modified Kirchhoff surface integral, containing only the imaginary part of this free reference space Green's function slowness spectrum, is formulated, yielding an integral equation for the unknown fields and sources in the interior of a closed surface on which the (remotely sensed) fields are known. A well-posed, analytic closed form solution of this integral equation is obtained.
An Adaptive Optics Search for Companions to Stars with Planets

We have performed a Keck adaptive optics (AO) imaging survey of 25 extrasolar planetary systems discovered by the radial velocity programs. Typically, the high-resolution (FWHM ~ 004) near-infrared images are able to detect point sources at ΔH = 10 at 1'', L and T dwarfs at 05-2'', and stars and brown dwarfs at 3-10 and 10-100 AU from the targets. The AO images reveal 15 faint sources (H = 14-20) near the stars HD 37124, HD 168443, HD 187123, and HD 190228 out to a search radius of 33. We have obtained AO images at a second epoch for five of the candidate companions at Keck and Gemini Observatories. The resulting measurements of proper motions relative to the primary stars indicate that these five sources are background stars. Given that the four primaries are near the Galactic plane (|b| < 6°), the remaining faint sources are also likely to be background stars rather than substellar companions. We present the companion detection limits for each target as a function of separation and compare them to the sensitivities of radial velocity surveys, demonstrating the complementary nature of the two techniques.
Reconsidering the Role of Memory in Religious Education.

AbstractThis article examines the importance of memory in the Hebrew bible and how memory lay at the center of Ancient Israel's religious faith and cultural identity. It argues for a similar, albeit nuanced, memory-based approach to contemporary Christian religious education. It analyzes memory through the lens of Paul Ricoeur's hermeneutic of narration and considers ways in which forgetting as well as remembering might play a role in faith formation and identity in the 21st century.
Airspace Sector Redesign Based on Voronoi Diagrams

Dynamic resectorization is a promising concept to accommodate the increasing and fluctuating demands of flight operations in the National Airspace System. At the core of dynamic resectorization is finding an optimal sectorization. Finding such an optimal sectorization is challenging, because it mixes the graph partition problem and non-deterministic polynomial-time-hard optimization problem. This paper revisits Voronoi diagrams and genetic algorithms, and proposes a strategy that combines these algorithms with the iterativedeepening algorithm. Voronoi diagrams accomplish the graph partition, which then needs to be optimized. By defining a multi-objective cost, the combination of the genetic algorithm and iterative deepening algorithm solves the optimization problem. Experimental results show that this method can accomplish sector design by setting an appropriate cost. Without a need of clustering, this method can capture the dominant flow, which is one of the major concerns in sector design. The design can have balanced aircraft count and low coordination. If the capacity is defined and incorporated into the cost, the sectorization will lead to a design with increased capacity. The whole process can be finished within a feasible time period without the need for parallel schemes.
General model of pressure-induced transition temperature increase with focus on the Hg-Ba-Ca-Cu-O system

Abstract A general calculation of high-pressure-induced transition temperature ( T c ) increases for oxide superconductors gives a good description for the Hg—Ba—Ca—Cu—O system. Predictions are made of the maximum T th c P ≈ 163, 154, and 111 K compared with T exp c P = 164, 154, and 118 K respectively for the superconducting phases of Hg-1223, Hg-1212, and Hg-1201 as a function of their compressibilities, agreeing with experiment. The theoretical result is in the form of a universal scaling equation for the fractional change in T c as a function of pressure, which is derived from a recent phenomenological theory of short coherence length superconductivity.
Gold(I)-Catalyzed Iodination of Arenes

A wide variety of electron-rich arenes were efficiently converted into the corresponding iodinated compounds via a gold(I)-catalyzed reaction under mild conditions.
Getting More For Your Money: Identifying and Confirming Long-Period Planets with Kepler

Kepler will monitor enough stars that it is likely to detect single transits of planets with periods longer than the mission lifetime. We show that by combining the Kepler photometry of such transits with precise radial velocity (RV) observations taken over ~3 months, and assuming circular orbits, it is possible to estimate the periods of these transiting planets to better than 20% (for planets with radii greater than that of Neptune) and the masses to within a factor of 2 (for planet masses m_p > M_Jup). We also explore the effects of eccentricity on our estimates of these uncertainties.
Laser-induced damage in pellicles at 193 nm

he effect of 1 93-nm excimer laser radiation on pellicles designed for 248-nm use is studied. The pellicles are transparent at 1 93 nm as well. However, prolonged irradiation causes gradual thinning and eventual rupture of the pellicle. The rate of change depends on the fluence and on the total dose but is not affected by the presence of atmospheric oxygen. Two-photon absorption plays an important role in the interaction between the laser and the pellicle material. Extrapolation to the approximately 0.1 mJ cm2lpulse fluences expected to be used in 1 93-nm steppers indicates that these pellicles will change little for 5everal years in a full-production environment.
Modeling Agent Social Joint Actions via Micro and Macro Coordination Strategies

This paper presents a multi-agent model for large crowd simulations that addresses the need for socially plausible coordination behavior. A computational model for multi-agent coordination informed by well-established common ground theory is proposed. We introduce the idea of macro- and micro-coordination strategies that allow agent-based simulations to adapt to different domains. Our agent model allows the selection of appropriate behaviors based on the spatiotemporal conditions of the agent-group's environment. By showing that different micro-coordination strategies of individual groups has an influence on the overall distribution of a crowd, we demonstrate the importance of incorporating such models into multi-agent simulations of large crowd behaviors.
Cascade flutter analysis with transient response aerodynamics

Two methods for calculating linear frequency domain aerodynamic coefficients from a time marching Full Potential cascade solver are developed and verified. In the first method, the Influence Coefficient, solutions to elemental problems are superposed to obtain the solutions for a cascade in which all blades are vibrating with a constant interblade phase angle. The elemental problem consists of a single blade in the cascade oscillating while the other blades remain stationary. In the second method, the Pulse Response, the response to the transient motion of a blade is used to calculate influence coefficients. This is done by calculating the Fourier Transforms of the blade motion and the response. Both methods are validated by comparison with the Harmonic Oscillation method and give accurate results. The aerodynamic coefficients obtained from these methods are used for frequency domain flutter calculations involving a typical section blade structural model. An eigenvalue problem is solved for each interblade phase angle mode and the eigenvalues are used to determine aeroelastic stability. Flutter calculations are performed for two examples over a range of subsonic Mach numbers.
Development of NSTX particle control techniques

Abstract Density control in NSTX, involves primarily controlling impurity influxes and recycling. We have compared boronization on hot and cold surfaces, varying helium glow discharge conditioning (HeGDC) durations, helium discharge cleaning, brief daily boronization, and between discharge boronization to reduce and control spontaneous density rises. Access to Ohmic H-modes was enabled by boronization on hot surfaces, however, the duration of the effectiveness of hot and cold boronization was comparable. A 15 min HeGDC between discharges was needed for reproducible L–H transitions. He discharge conditioning yielded slower density rises than 15 min of HeGDC. Brief daily boronization followed by a comparable duration of applied HeGDC restored and enhanced good conditions. Additional brief boronizations between discharges did not improve plasma performance, if conditions were already good. Between discharge boronization required increases in the NSTX duty cycle due to the need for additional HeGDC to remove codeposited D.
Semistable abelian varieties over Q

We prove that for N=6 and N=10, there do not exist any non-zero semistable abelian varieties over ℚ with good reduction outside primes dividing N. Our results are contingent on the GRH discriminant bounds of Odlyzko. Combined with recent results of Brumer-Kramer and of Schoof, this result is best possible: if N is squarefree, there exists a non-zero semistable abelian variety over ℚ with good reduction outside primes dividing N precisely when N∉{1,2,3,5,6,7,10,13}.