cssi/SciSciGPT-SciSciNet huggingface dataset:
Bid, ask and transaction prices in a specialist market with heterogeneously informed traders

The presence of traders with superior information leads to a positive bid-ask spread even when the specialist is risk-neutral and makes zero expected profits. The resulting transaction prices convey information, and the expectation of the average spread squared times volume is bounded by a number that is independent of insider activity. The serial correlation of transaction price differences is a function of the proportion of the spread due to adverse selection. A bid-ask spread implies a divergence between observed returns and realizable returns. Observed returns are approximately realizable returns plus what the uninformed anticipate losing to the insiders.
N identical particles under quantum confinement: a many-body dimensional perturbation theory approach

Systems that involve N identical interacting particles under quantum confinement appear throughout many areas of physics, including chemical, condensed matter, and atomic physics. In this paper, we present the methods of dimensional perturbation theory, a powerful set of tools that uses symmetry to yield simple results for studying such many-body systems. We present a detailed discussion of the dimensional continuation of the N-particle Schrodinger equation, the spatial dimension D→∞ equilibrium (D0) structure, and the normal-mode (D−1) structure. We use the FG matrix method to derive general, analytical expressions for the many-body normal-mode vibrational frequencies, and we give specific analytical results for three confined N-body quantum systems: the N-electron atom, N-electron quantum dot, and N-atom inhomogeneous Bose–Einstein condensate with a repulsive hard-core potential.
Explosive ordnance detection in land and water environments with solid phase extraction/ion mobility spectrometry

The qualitative and quantitative determination of nitroaromatic compounds such as trinitrotoluene (TNT) and dinitrotoluene (DNT) in water and soil has applications to environmental remediation and the detection of buried military ordnance. Recent results of laboratory and field test have shown that trace level concentrations of these compounds can be detected in water, soil, and solid gas samples taken from the vicinity of submerged or buried ordnance using specialized sampling and signal enhancement techniques. Solid phase micro-extraction methods have been combined with Ion Mobility Spectroscopy to provide rapid, sub-parts-per-billion analysis of these compounds. In this paper, we will describe the gas. These sampling systems, when combined with field-portable IMS, are being developed as a means of classifying buried or submerged objects as explosive ordnance.
On the modeling and optimal flow control of the Jacksonian network

Abstract The modeling and optimal flow control of a Jacksonian network in equilibrium is investigated. The model employed consists of a controller node cascaded with the Jacksonian network. Input packets arrive at the controller node with a Poissonian rate δ. For a blocking type strategy for accessing the network it is shown that the control which maximizes the average throughput of the network subject to a bounded average time delay constraint is a window flow control mechansim. The window size depends on the offered load δ, the maximum service rate of the controlling queueing system, c , and the Norton equivalent service rate of the network μ. The dependence of the average throughput and the average time delay on the control is also analyzed.
Women in white

The author uses an allegory based on personal experience to explore assumptions about our identity as nurses and our perceptions of patients.
The behavioral justification for public pensions: a survey

Unfunded public pension systems are primarily justified on grounds that many individuals lack sufficient capacity to appropriately save for retirement. We begin with a review of the known principle that a standard life-cycle/permanent-income consumer who discounts the future at an exponential rate can benefit from an unfunded public pension system only if the internal rate of return exceeds the private rate of return. However, a pay-as-you-go program with a below market internal rate can in fact improve lifetime utility if the consumer misestimates social security benefits, uses a hyperbolic discount function rather than the exponential function, uses a short planning horizon, behaves impulsively, or if a fraction of the population do no saving at all. A literature has consequently arisen to study how severe these behavioral defects need to be in order to justify a pay-as-you-go program. We survey this literature, and we conclude that the results are highly mixed as to whether an unfunded public pension that earns a below-market internal rate of return can be justified on grounds of shortsightedness in model economies. The challenge for this literature is that the conclusions crucially depend on the particular values of the preference parameters that are used in the simulation experiments, and these preference parameters are not observable, nor is there much consensus concerning the values that should be used in simulations. In fact, even when the analysis is confined to a small and reasonable space of the unobservable preference parameters, it is possible to reach nearly any policy conclusion. We offer some guidance for future work in this area.
Biomolecular transport through hemofiltration membranes

A theoretical model for filtration of large solutes through a pore in the presence of transmembrane pressures, applied/induced electric fields, and dissimilar interactions at the pore entrance and exit is developed to characterize and predict the experimental performance of a hemofiltration membrane with nanometer scale pores designed for a proposed implantable Renal Assist Device (RAD). The model reveals that the sieving characteristics of the membrane can be improved by applying an external electric field, and ensuring a smaller ratio of the pore-feed and pore-permeate equilibrium partitioning coefficients when diffusion is present. The model is then customized to study the sieving characteristics for both charged and uncharged solutes in the slit-shaped nanopores of the hemofiltration device for the RAD. The effect of streaming potential or induced fields are found to be negligible under representative operating conditions. Experimental data on the sieving coefficient of bovine serum albumin, carbonic anhydrase and thyroglobulin are reported and compared with the theoretical predictions. Both steric and electrostatic partitioning are considered and the comparison suggests that in general electrostatic effects are present in the filtration of proteins though some data, particularly those recorded in a strongly hypertonic solution (10× PBS), show better agreement with the steric partitioning theory.
The Chemistry of Bulk Hydrogen: Reaction of Hydrogen Embedded in Nickel with Adsorbed CH3

Studies in heterogeneous catalysis have long speculated on or have provided indirect evidence for the role of hydrogen embedded in the catalyst bulk as a primary reactant. This report describes experiments carried out under single-collision conditions that document the distinctive reactivity of hydrogen embedded in the bulk of the metal catalyst. Specifically, the bulk H atom is shown to be the reactive species in the hydrogenation of CH 3 adsorbed on Ni(111) to form CH 4 , while the H atoms bound to the surface were unreactive. These results unambiguously demonstrate the importance of bulk species to heterogeneous catalytic chemistry.
Asymmetric catalysis with chiral oxazolidine ligands

Asymmetric catalysis with chiral 1,3-oxazolidine ligands, which have a sterically tunable, rigid structure that can accommodate several chiral centers, has found increasing attention in recent years. This trend is partly due to the intriguing ring topology of oxazolidines and the prospect of modular synthesis of a diverse set of ligands from a wide range of readily available amino alcohols. The general promise and pitfalls of the synthesis of chiral oxazolidines and the success of selected catalysts including pyridinyl and phosphine derivatives in asymmetric alkylations, alkynylations, allylic alkylations, cycloadditions, and aldol reactions is discussed.
Tax burden, government expenditures and income distribution in Brazil

Abstract This article attempts to explain the seeming paradox of a country with a high tax burden and a continually concentrated distribution of income. By means of a structural quantile regression model we analyze the distributional impact of government expenditures on the Gini index, and it is shown that Brazil's redistribution expenditures has a relatively smaller impact for low quantiles of the conditional distribution of income inequality. It is also noted that both the country's tax and expenditure structure are, in part, responsible for the country's continuous concentration of income.
SINR Statistics of Correlated MIMO Linear Receivers

Linear receivers offer a low complexity option for multiantenna communication systems. Therefore, understanding the outage behavior of the corresponding SINR is important in a fading mobile environment. In this paper, we introduce a large deviation method, valid nominally for a large number M of antennas, which provides the probability density of the SINR of Gaussian channel MIMO minimum mean square error (MMSE) and zero-forcing (ZF) receivers, with arbitrary transmission power profiles and in the presence of receiver antenna correlations. This approach extends the Gaussian approximation of the SINR, valid for large M asymptotically close to the center of the distribution, to obtain the non-Gaussian tails of the distribution. Our methodology allows us to calculate the SINR distribution to next-to-leading order ( O(1/M)) and showcase the deviations from approximations that have appeared in the literature (e.g., the Gaussian or the generalized Gamma distribution). We also analytically evaluate the outage probability, as well as the uncoded bit-error-rate. We find that our approximation is quite accurate even for the smallest antenna arrays (2 × 2).
Polymorphic one-dimensional (N2H4)2ZnTe: soluble precursors for the formation of hexagonal or cubic zinc telluride.

Two hydrazine zinc(II) telluride polymorphs, (N2H4)2ZnTe, have been isolated, using ambient-temperature solution-based techniques, and the crystal structures determined: α-(N2H4)2ZnTe (1) [P21, a = 7.2157(4) A, b = 11.5439(6) A, c = 7.3909(4) A, β = 101.296(1)°, Z = 4] and β-(N2H4)2ZnTe (2) [Pn, a = 8.1301(5) A, b = 6.9580(5) A, c = 10.7380(7) A, β = 91.703(1)°, Z = 4]. The zinc atoms in 1 and 2 are tetrahedrally bonded to two terminal hydrazine molecules and two bridging tellurium atoms, leading to the formation of extended one-dimensional (1-D) zinc telluride chains, with different chain conformations and packings distinguishing the two polymorphs. Thermal decomposition of (N2H4)2ZnTe first yields crystalline wurtzite (hexagonal) ZnTe at temperatures as low as 200 °C, followed by the more stable zinc blende (cubic) form at temperatures above 350 °C. The 1-D polymorphs are soluble in hydrazine and can be used as convenient precursors for the low-temperature solution processing of p-type ZnTe semiconduct...
Intervals and the deduction of drug binding site models

In the search for new drugs, it often occurs that the binding affinities of several compounds to a common receptor macromolecule are known experimentally, but the structure of the receptor is not known. This article describes an extraordinarily objective computer algorithm for deducing the important geometric and energetic features of the common binding site, starting only from the chemical structures of the ligands and their observed binding. The user does not have to propose a pharmacophore, guess the bioactive conformations of the ligands, or suggest ways to superimpose the active compounds. The method takes into account conformational flexibility of the ligands, stereospecific binding, diverse or unrelated chemical structures, inaccurate or qualitative binding data, and the possibility that chemically similar ligands may or may not bind to the receptor in similar orientations. The resulting model can be viewed graphically and interpreted in terms of one or more binding regions of the receptor, each preferring to be occupied by various sorts of chemical groups. The model always fits the given data completely and can predict the binding of any other ligand, regardless of chemical structure. The method is an outgrowth of distance geometry and Voronoi polyhedra site modeling but incorporates several novel features. The geometry of the ligand molecules and the site is described in terms of intervals of internal distances. Determining the site model consists of reducing the uncertainty in the interregion distance intervals, and this uncertainty is described as intervals of intervals. Similarly, the given binding affinities and their experimental uncertainties are treated as intervals in the affinity scale. The final site model specifies an entire region of interaction energy parameters that satisfy the training set rather than a single set of parameters. Predicted binding for test compounds results in an interval which, when compared to the experimental interval, may be correct, incorrect, or vague. There is a pervasive ternary logic involved in the assessment of predictions, in the search for a satisfactory model, and in judging whether a given molecule may bind in a particular orientation: true, false, or maybe. The approach is illustrated on an extremely simple artificial example and on a real data set of cocaine analogues binding to a nerve membrane receptor in vitro. © 1995 by John Wiley & Sons, Inc.
Oscillating aerodynamics and flutter of an aerodynamically detuned cascade in an incompressible flow

A mathematical model is developed and utilized to demonstrate the enhanced torsion mode stability associated with alternate blade circumferential aerodynamic detuning of a rotor operating in an incompressible flow field. The oscillating cascade aerodynamics, including steady loading effects, are determined by developing a complete first order unsteady aerodynamic analysis. An unsteady aerodynamic influence coefficient technique is then utilized, thereby enabling the stability of both conventional uniformly spaced rotors and detuned nonuniform circumferentially spaced rotors to be determined. To demonstrate the enhanced flutter aeroelastic stability associated with this aerodynamic detuning mechanism, this model is applied to a baseline unstable rotor with a Gostelow flow geometry.
An analysis of Pluto occultation light curves using an atmospheric radiative–conductive model

Abstract We use a radiative–conductive model to least-squares fit Pluto stellar occultation light curve data. This model predicts atmospheric temperature based on surface temperature, surface pressure, surface radius, and CH4 and CO mixing ratios, from which model light curves are to be calculated. The model improves upon previous techniques for deriving Pluto’s atmospheric thermal structure from stellar occultation light curves by calculating temperature (as a function of height) caused by heating and cooling by species in Pluto’s atmosphere, instead of a general assumption that temperature follows a power law with height or some other idealized function. We are able to fit for model surface radius, surface pressure, and CH4 mixing ratio with one of the 2006 datasets and for surface pressure and CH4 mixing ratio for other datasets from the years 1988, 2002, 2006, and 2008. It was not possible to fit for CO mixing ratio and surface temperature because the light curves are not sensitive to these parameters. We determine that the model surface radius, under the assumption of a stratosphere only (i.e. no troposphere) model in radiative–conductive balance, is 1180 - 10 + 20 km . The CH4 mixing ratio results are more scattered with time and are in the range of 1.8–9.4 × 10−3. The surface pressure results show an increasing trend from 1988 to 2002, although it is not as dramatic as the factor of 2 from previous studies.
Bounds on anomalous gauge boson couplings from partial Z widths at LEP

We place bounds on anomalous gauge boson couplings from LEP data with particular emphasis on those couplings which do not contribute to Z decays at tree level. We use an effective field theory formalism to compute the one-loop corrections to the Z → f f decay widths resulting from non-standard model three and four gauge boson vertices. We find that the precise measurements at LEP constrain the three gauge boson couplings at a level comparable to the obtainable at LEP II LEP constrain the three gauge boson couplings at a level comparable to that obtainable at LEP II and LHC.
Privacy, Efficiency, and the Equality of Men and Women: A Revisionist View of Sex Discrimination in Employment

The Supreme Court's decision in City of Los Angeles Department of Water and Power v. Manhart has engendered a considerable debate, much of which has appeared in the pages of this Journal. Defenders of the Manhart decision take its critics to task for failure to appreciate the place of that decision in the overall jurisprudence of employment discrimination. In this article, the authors challenge the underlying conception of the law of sex discrimination that is said to dictate the result in Manhart. Far from erecting a per se rule against all sex classifications, the Civil Rights Act of 1964 is shown to recognize both the relevance of prevalent social norms about sex differences and the legitimacy of certain interests of employers as limited justifications for the maintenance of sex-conscious lines in some circumstances, a recognition that contrasts sharply with the statute's categorical prohibition on racial classifications. It follows from this discussion that Manhart's outcome was not ordained by the ethos of the laws against sex discrimination.
Restriction of characters and products of characters

Let G be a finite p-group, for some prime p, and ψ, θ ∈ Irr(G) be irreducible complex characters of G. It has been proved that if, in addition, ψ and θ are faithful characters, then the product ψθ is a multiple of an irreducible or it is the nontrivial linear combination of at least (p + 1)/2 distinct irreducible characters of G. We show that if we do not require the characters to be faithful, then given any integer k > 0, we can always find a p-group P and irreducible characters Ψ and Θ of P such that the product ΨΘ is the nontrivial combination of exactly k distinct irreducible characters. We do this by translating examples of decompositions of restrictions of characters into decompositions of products of characters.
An assessment of the impact of pregnancy on trauma mortality.

Background In the United States, trauma is the leading cause of maternal mortality and an important source of maternal morbidity. Few studies have compared outcomes in injured pregnant women to their nonpregnant counterparts. Some clinical literature regarding hormonal influences on outcomes after trauma suggests a survival advantage in premenopausal women with higher estrogen levels. Given this, as well as possible outcome differences as a result of physiologic changes that occur during pregnancy, we tested the hypothesis that pregnant women have different outcomes after trauma compared with similarly injured nonpregnant women in the same age groups. Methods We used data derived from 1.46 million patients listed in The National Trauma Data Bank from 2001 to 2005, to query all injured patients between ages 12 and 49 years inclusive, and divided them into 2 comparison groups: nonpregnant and pregnant women. We compared differences in outcome after trauma between pregnant and nonpregnant women. Because the number of pregnant women was small in comparison to the number of nonpregnant women, multivariate analysis after 1:3 (pregnant:nonpregnant) matching was attempted. Results Crude mortality rate comparisons and unadjusted logistic regression analyses both before and after matching data reveal lower mortality rates in pregnant women. Multivariate logistic regression analyses both before and after matching data also reveal lower mortality rates in pregnant women; but this is statistically significant (P = .01) only after matching data. Conclusion Among women of similar age groups who are equivalently injured, those who are pregnant exhibit lower mortality. These findings suggest that hormonal and physiologic differences during the gestation period may play a role in outcomes following trauma in pregnant women.
Verbal Processing Speed and Executive Functioning in Long-Term Cochlear Implant Users.

Purpose The purpose of this study was to report how verbal rehearsal speed (VRS), a form of covert speech used to maintain verbal information in working memory, and another verbal processing speed measure, perceptual encoding speed, are related to 3 domains of executive function (EF) at risk in cochlear implant (CI) users: verbal working memory, fluency-speed, and inhibition-concentration. Method EF, speech perception, and language outcome measures were obtained from 55 prelingually deaf, long-term CI users and matched controls with normal hearing (NH controls). Correlational analyses were used to assess relations between VRS (articulation rate), perceptual encoding speed (digit and color naming), and the outcomes in each sample. Results CI users displayed slower verbal processing speeds than NH controls. Verbal rehearsal speed was related to 2 EF domains in the NH sample but was unrelated to EF outcomes in CI users. Perceptual encoding speed was related to all EF domains in both groups. Conclusions Verba...
Measuring the Employer's Return on Investments in Training: Evidence from the Literature

Three components of the literature on measuring the employer's rate of return to investments in employee training are reviewed: (1) studiesthat use large samples of firm-level or establishment-level data collected through mail or phone surveys, (2) studies that use data from one or two companies to conduct an ‘econometric’ case study, and (3) company-sponsored case studies. The strengths and weaknesses of each of these approaches are evaluated and the estimated returns on investments (ROIs) are compared. The analysis indicates that the employer's return on investments in training may be much higher than previously believed. In order to obtainaccurate information on the employer's ROI from training, researchers should be encouraged to gain access to company databases and to supplement them with data-gathering efforts to collect information on variables needed to isolate the effect of training.
THE FUNCTOR OF A SMOOTH TORIC VARIETY

(1) Y 7→ {line bundle quotients of O Y } . This is easy to prove since a surjection O Y → L gives n + 1 sections of L which don’t vanish simultaneously and hence determine a map Y → Pnk . The goal of this paper is to generalize this representation to the case of an arbitrary smooth toric variety. We will work with schemes over an algebraically closed field k of characteristic zero, and we will fix a smooth n-dimensional toric variety X determined by the fan ∆ in NR = R. As usual, M denotes the dual lattice of N and ∆(1) denotes the 1-dimensional cones of ∆. We will use ∑
Uniform pointwise bounds for matrix coefficients of unitary representations on semidirect products

Abstract Let k be a local field of characteristic 0, and let G be a connected semisimple almost k-algebraic group. Suppose rank k G ⩾ 1 and ρ is an excellent representation of G on a finite dimensional k-vector space V. We construct uniform pointwise bounds for the K-finite matrix coefficients restricted on G of all unitary representations of the semi-direct product G ⋉ ρ V without non-trivial V-fixed vectors. These bounds turn out to be sharper than the bounds obtained from G itself for some cases. As an application, we discuss a simple method of calculating Kazhdan constants for various compact subsets of the pair ( G ⋉ ρ V , V ) .
Astronomical science with laser guide star adaptive optics: a brief review, a current snapshot, and a bright future

We briefly discuss the past, present, and future state of astronomical science with laser guide star adaptive optics (LGS AO). We present a tabulation of refereed science papers from LGS AO, amounting to a total of 23 publications as of May 2006. The first decade of LGS AO science (1995-2004) was marked by modest science productivity (≈1 paper/year), as LGS systems were being implemented and commissioned. The last two years have seen explosive science growth (≈1 paper/month), largely due to the new LGS system on the Keck II 10-meter telescope, and point to an exciting new era for high angular resolution science. To illustrate the achievable on-sky performance, we present an extensive collection of Keck LGS performance measurements from the first year of our brown dwarf near-IR imaging survey. We summarize the current strengths and weaknesses of LGS compared to Hubble Space Telescope , offer a list of desired improvements, and look forward to a bright future for LGS given its wide-scale implementation on large ground-based telescopes.
Comparing welfare estimates of environmental quality changes from recreation demand models

Abstract This paper presents a procedure for examining the reliability of welfare estimates resulting from the estimation of multiple site recreation demand models. A simulation approach is suggested where a utility function is combined with observations on individual and site characteristics to generate simulated data sets. Welfare measures associated with an improvement in site quality are calculated. Recreation demand models are estimated using the simulated data sets. Estimated welfare measures resulting from the recreation demand models are then compared to the true welfare measures calculated from the simulated data. The procedure is demonstrated using two commonly employed recreation demand models.
Microbial reduction of uranium

REDUCTION of the soluble, oxidized form of uranium, U(VI), to insoluble U(IV) is an important mechanism for the immobilization of uranium in aquatic sediments and for the formation of some uranium ores1–10. U(VI) reduction has generally been regarded as an abiological reaction in which sulphide, molecular hydrogen or organic compounds function as the reductant1,2,5,11. Microbial involvement in U(VI) reduction has been considered to be limited to indirect effects, such as microbial metabolism providing the reduced compounds for abiological U(VI) reduction and microbial cell walls providing a surface to stimulate abiological U(VI) reduction1,12,13. We report here, however, that dissimilatory Fe(III)-reducing microorganisms can obtain energy for growth by electron transport to U(VI). This novel form of microbial metabolism can be much faster than commonly cited abiological mechanisms for U(VI) reduction. Not only do these findings expand the known potential terminal electron acceptors for microbial energy transduction, they offer a likely explanation for the deposition of uranium in aquatic sediments and aquifers, and suggest a method for biological remediation of environments contaminated with uranium.
The adiabatic instability on cosmology's dark side

We consider theories with a nontrivial coupling between the matter and dark energy sectors. We describe a small scale instability that can occur in such models when the coupling is strong compared to gravity, generalizing and correcting earlier treatments. The instability is characterized by a negative sound speed squared of an effective coupled dark matter/dark energy fluid. Our results are general, and applicable to a wide class of coupled models and provide a powerful, redshift-dependent tool, complementary to other constraints, with which to rule many of them out. A detailed analysis and applications to a range of models are presented in a longer companion paper.
Open questions in classical gravity

We discuss some outstanding open questions regarding the validity and uniqueness of the standard second-order Newton-Einstein classical gravitational theory. On the observational side we discuss the degree to which the realm of validity of Newton's law of gravity can actually be extended to distances much larger than the solar system distance scales on which the law was originally established. On the theoretical side we identify some commonly accepted (but actually still open to question) assumptions which go into the formulation of the standard second-order Einstein theory in the first place. In particular, we show that while the familiar second-order Poisson gravitational equation (and accordingly its second-order covariant Einstein generalization) may be sufficient to yield Newton's law of gravity they are not in fact necessary. The standard theory thus still awaits the identification of some principle which would then make it necessary too. We show that current observational information does not exclusively mandate the standard theory, and that the conformal invariant fourth-order theory of gravity considered recently by Mannheim and Kazanas is also able to meet the constraints of data, and in fact to do so without the need for any so far unobserved nonluminous or dark matter.
Cartan Determinants and Shapovalov forms

We compute the determinant of the Gram matrix of the Shapovalov form on weight spaces of the basic representation of an affine Kac-Moody algebra of ADE type (possibly twisted). As a consequence, we obtain explicit formulae for the determinants of the Cartan matrices of p-blocks of the symmetric group and its double cover, and of the associated Hecke algebras at roots of unity.
Operatorial construction of multiple charged-pion amplitudes☆

Abstract It is shown that taking the “chiral symmetry” result α ϱ (0)−α π (0)= 1 2 as a hypothesis allows straightforward use of the oscillator formalism to construct 4π and 6π amplitudes with no tachyon ghosts, and full Regge behaviour. An attempt is made to isolate which features of such schemes, needed to generalize the Lovelace amplitude, lead to problematic results in the multi-pion amplitudes which are obtained.
Impulsive stimulated Raman scattering of molecular vibrations using nonlinear pulse shaping

We demonstrate the excitation of a molecular vibrational coherence via impulsive stimulated Raman scattering (ISRS) by using a pump pulse longer than the vibrational period of the excited mode. By making use of the reshaping of the pump pulse during nonlinear propagation, a Raman vibrational coherence can be excited via ISRS with a pump pulse incapable of such excitation at the input of the medium.
Numerical investigation of high incidence flow over a double-delta wing

The vortical flowfield over a double-delta wing configuration, consisting of a sharp leading-edge 76-deg sweep strake and a 40-deg sweep wing section is investigated numerically. The governing equations are solved with a partially upwind, finite difference, two-factor algorithm. The leeward-side vortex system resulting from the strake and wing vortices is investigated for a subsonic freestream speed of M^ = 0.22, high Reynolds number turbulent flow at various angles of incidence. At low angles of attack the strake and wing vortices remain separate over the wing section, whereas for flows at higher angles of attack the two vortices merge and vortex breakdown develops. Vortex breakdown appears initially in the trailing-edge region of the wing section. As the angle of attack increases, bursting occurs further upstream closer to the strake section. The effect of numerical grid density is investigated, and the solutions are compared with available experimental data. The computed surface pressures are in good agreement with the experimental measurements for the lower angles of attack, but the agreement deteriorates as the angle of attack increases.
Benefits on the margin : observations on marginal benefit incidence

Benefit incidence analysis has become a popular tool over the past decade, especially for researchers at the World Bank. Despite or perhaps because of the popularity of this method, recent research has pointed out many of its limitations. One of the most common criticisms of benefit incidence analysis is that its description of average participation rates is not necessarily useful in guiding marginal changes in public spending policies. This article considers a variety of methods for analyzing the marginal benefit incidence of policy changes. A key conceptual point is that despite the fact that the various methods measure marginal incidence, they do not measure the same thing nor are they intended to do so. There are many possible policy changes and thus many margins of interest. Each method captures one of these and so is of interest for some analyses and inappropriate for others. Empirically, the precision of the methods differs substantially, with those relying on differenced data or aggregations of households yielding standard errors that are quite large relative to the estimated shares.
Interobserver variability associated with the MIB-1 labeling index: high levels suggest limited prognostic usefulness for patients with primary brain tumors.

BACKGROUND The use of the MIB-1 labeling index (LI) as a potential prognostic marker for patients with primary brain tumors is controversial. Many studies advocating its prognostic usefulness have suggested discrete MIB-1 LI cut-off values, above which patients have significantly worse outcomes. However, interobserver variability associated previously with MIB-1 LI calculation has not been reported despite the fact that the degree of interobserver variability impacts the clinical usefulness of such cut-off values. METHODS MIB-1 LIs were calculated independently using a standardized protocol by six pathologist observers for 50 astrocytic gliomas of varying grades. The level of interobserver agreement was determined by calculating kappa statistics for pairwise pathologist comparisons using MIB-1 LI cut-off values of 2.5%, 5.0%, 8.0%, 11.0%, and 15.0%. Spearman rank correlation coefficients were used to assess the pairwise associations between observer MIB-1 LIs. RESULTS Although there was general agreement among pathologists regarding whether an MIB-1 LI for a given astroglial tumor was low, moderate, or high based on the analysis of correlation, a high level of interobserver variability was associated with the determination of specific MIB-1 LIs. The highest level of agreement occurred using a cut-off value of 5.0%, with pairwise kappa statistics for this value ranging from 0.52 to 0.80. CONCLUSIONS The high level of interobserver variability suggests that proposed discrete MIB-1 LI prognostic cut-off values most likely are not useful clinically for predicting outcome for individual patients with primary brain tumors. Further prospective studies are needed investigating the prognostic usefulness of MIB-1 LI ranges that optimize interobserver agreement. Cancer 2001;92:2720–6. © 2001 American Cancer Society.
Relationship between B-site order and properties in Pb(B′B″)O3 perovskites

Abstract A simple classification scheme is presented which essentially relates the scale of B-site cation order in complex lead based perovskites Pb(B′B″)O3 with either normal ferroelectric (antiferroelectric) or relaxor ferroelectric behavior, as observed in these materials.
Least expected cost query optimization: an exercise in utility

We identify two unreasonable, though standard, assumptions made by database query optimizers that can adversely affect the quality of the chosen evaluation plans. One assumption is that it is enough to optimize for the expected case---that is, the case where various parameters (like available memory) take on their expected value. The other assumption is that the parameters are constant throughout the execution of the query. We present an algorithm based on the ``System R''-style query optimization algorithm that does not rely on these assumptions. The algorithm we present chooses the plan of the least expected cost instead of the plan of least cost given some fixed value of the parameters. In execution environments that exhibit a high degree of variability, our techniques should result in better performance.
Nonlocal Lagrangians for accelerated systems

Acceleration-induced nonlocality and the corresponding Lorentz-invariant nonlocal field equations of accelerated systems in Minkowski spacetime are discussed. Under physically reasonable conditions, the nonlocal equation of motion of the field can be derived from a variational principle of stationary action involving a nonlocal Lagrangian that is simply obtained by composing the local inertial Lagrangian with the nonlocal transformation of the field to the accelerated system. The implications of this approach for the electromagnetic and Dirac fields are briefly discussed.
Functionalization of the 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) core

The new BODIPY systems 1 and 2 were prepared and then used as substrates to explore S(N)Ar and F-B displacement reactions. Chloride was easily displaced from 1 by a piperidine/ester, methylmagnesium bromide selectively displaced fluoride, and cyanide could attack both sites. System 2 readily added soft nucleophiles to the electrophilic carbon atoms, providing a new method for bioconjugation of BODIPYs to proteins while also introducing a (19)F probe.
Grain-oriented fabrication of bismuth titanate ceramics and its electrical properties

The concept of grain-oriented fabrication in ceramics, which utilizes anisotropy either in morphology or some specific property of the particle, is reviewed. A fabrication method, which maximizes the grain orientation, is described for Bi/sub 4/Ti/sub 3/O/sub 12/. The process utilized plate-like morphology of Bi/sub 4/Ti/sub 3/O/sub 12/ particles and yielded a ceramic with an X-ray density of 95.4% and an unprecedented value of 100% for Lotgering's orientation factor in the direction of orientation. The dielectric and piezoelectric properties of this ceramic are described and compared to single crystal values. Complex impedance analysis of the ceramics was used to explain the dielectric relaxations at elevated temperatures. The use of grain-oriented fabrication as a practical technique for making polycrystalline ceramics with electrical properties close to those of single crystals (in the direction of orientation) is emphasized. The use of grain-oriented Bi/sub 4/Ti/sub 3/O/sub 12/ ceramics as a high-temperature piezoelectric transducer is suggested. >
On the mixed even-spin Sherrington–Kirkpatrick model with ferromagnetic interaction

Nous etudions un systeme dont les spins ont a la fois des couplages du type Sherrington–Kirkpatrick (SK) et des interactions du type Curie–Weiss (CW). Nos principaux resultats sont les suivants : (i) la limite thermodynamique de l’energie libre est donnee par une formule variationnelle impliquant l’energie libre du modele SK avec un changement dans le champ magnetique externe. (ii) En presence d’un champ exterieur Gaussien centre, le recouvrement est positif et les identites generalisees de Ghirlanda–Guerra sont valides pour un sous ensemble dense des parametres de temperature. (iii) Nous etablissons une inegalite generale entre l’aimantation et le recouvrement. (iv) Nous identifions un domaine de temperatures ou l’aimantation peut etre controlee quantitativement et nous deduisons plusieurs types de convergences pour l’aimantation en presence ou non d’un champ exterieur. Notre approche repose sur des methodes developpees pour l’etude des modeles CW et SK et sur des resultats d’analyse convexe.
Precession dynamics in spin-orbit coupling: A unified theory

Taking into account the entire spectrum of potential harmonics, equations are developed for the secular motions of the node and pericenter referred to the invariant plane in a two-body problem when one is a sphere and the other a spinning asymmetrical rigid body (e.g., sun-planet system, or point satellite-planet system). Oblateness precession of satellite orbits and equinoctial precession of planets are shown to be merely opposite extreme cases of the single phenomenon of precession in spin-orbit coupling, in which the determining parameter is the ratio of orbital to spin angular momentum (ho/hs). The “critical” inclination for apsidal motion also depends on this ratio, varying from 63.43° in the one extreme when (ho/hs) ≪ 1, to 90° in the opposite extreme when (ho/hs) ≫ 1. Application is made to the earth-sun-moon system. (The full text of this lecture appeared in Celestial Mechanics, Vol. 32, pp 355–364, 1984.)
Determining contrast sensitivity functions for monochromatic light emitted by high-brightness LEDs

Light-emitting diode (LED) technology is becoming the choice for many lighting applications that require monochromatic light. However, one potential problem with LED-based lighting systems is uneven luminance patterns. Having a uniform luminance distribution is more important in some applications. One example where LEDs are becoming a viable alternative and luminance uniformity is an important criterion is backlighted monochromatic signage. The question is how much uniformity is required for these applications. Presently, there is no accepted metric that quantifies luminance uniformity. A recent publication proposed a method based on digital image analysis to quantify beam quality of reflectorized halogen lamps. To be able to employ such a technique to analyze colored beams generated by LED systems, it is necessary to have contrast sensitivity functions (CSFs) for monochromatic light produced by LEDs. Several factors including the luminance, visual field size, and spectral power distribution of the light affect the CSFs. Although CSFs exist for a variety of light sources at visual fields ranging from 2 degrees to 20 degrees, CSFs do not exist for red, green, and blue light produced by high-brightness LEDs at 2-degree and 10-degree visual fields and at luminances typical for backlighted signage. Therefore, the goal of the study was to develop a family of CSFs for 2-degree and 10-degree visual fields illuminated by narrow-band LEDs at typical luminances seen in backlighted signs. The details of the experiment and the results are presented in this manuscript.
Hidden symmetries in two dimensional field theory

Abstract The bosonization process elegantly shows the equivalence of massless scalar and fermion fields in two space-time dimensions. However, with multiple fermions the technique often obscures global symmetries. Witten’s non-Abelian bosonization makes these symmetries explicit, but at the expense of a somewhat complicated bosonic action. Frenkel and Kac have presented an intricate mathematical formalism relating the various approaches. Here, I reduce these arguments to the simplest case of a single massless scalar field. In particular, using only elementary quantum field theory concepts, I expose a hidden SU (2) × SU (2) chiral symmetry in this trivial theory. I then discuss in what sense this field should be interpreted as a Goldstone boson.
The effects of loop excision of the transformation zone on cervical length: implications for pregnancy.

Abstract Objective: This study was undertaken to determine whether previously described significant and quantitative cervical shortening caused by loop excision of the transformation zone persists after 3 months of healing. Study Design: A prospective study was designed in which 20 patients were enrolled. Each underwent transvaginal ultrasonography for determination of cervical length before the loop excision of the transformation zone and ≥3 months after the loop excision of the transformation zone. Simple regression analysis and the Student paired t test was performed to determine whether the length of the cervix had changed significantly between the measurements. Results: The mean cervical lengths as measured by transvaginal ultrasonography before and after loop excision of the transformation zone were 3.1 ± 0.8 cm and 3.1 ± 0.7 cm, respectively. The correlation between ultrasonographic measurements before and after loop excision of the transformation zone was r = 0.88 ( P t test resulted in a P value of 1.0000, which indicates that the ultrasonographic measurement after loop excision of the transformation zone was not different from the ultrasonographic measurement before loop excision of the transformation zone. The mean difference between measurements was 0.0 ± 0.4 cm. Conclusion: After adequate healing time after loop excision of the transformation zone, the length of the cervix, as measured by transvaginal ultrasonography, does not appear to remain shortened. (Am J Obstet Gynecol 2000;182:516-20.)
A Constraint on the Gravitational Lensing Magnification and Age of the Redshift z=6.28 Quasar SDSS 1030+0524

The recent discovery of bright quasars at redshift z ~ 6 suggests that black holes (BHs) with masses in excess of ~109 M☉ have already assembled at a very early stage in the evolution of the universe. An alternative interpretation is that these quasars are powered by less massive BHs, but their fluxes are strongly magnified through gravitational lensing by intervening galaxies. Here we analyze the flux distribution of the Lyα emission of the quasar with the highest known redshift, SDSS 1030+0524, at z = 6.28. We show that this object could not have been magnified by lensing by more than a factor of ~5. The constraint arises from the large observed size, ~30 (comoving) Mpc, of the ionized region around this quasar and relies crucially only on the assumption that the quasar is embedded in a largely neutral intergalactic medium. Based on the line/continuum ratio of SDSS 1030+0524, we further argue that this quasar also cannot be beamed by a significant factor. We conclude that the minimum mass for its resident BH is 4 × 108 M☉ (for magnification by a factor of 5); if the mass is this low, then the quasars had to switch on prior to redshift zf 9. From the size of the ionized region, we are also able to place an absolute lower bound on the age of this quasar at tQ > 2 × 107 yr.
Fundamental performance limits in image registration

The task of image registration is fundamental in image processing. It often is a critical preprocessing step to many modern image processing and computer vision tasks, and many algorithms and techniques have been proposed to address the registration problem. Often, the performances of these techniques have been presented using a variety of relative measures comparing different estimators, leaving open the critical question of overall optimality. In this paper, we present the fundamental performance limits for the problem of image registration as derived from the Cramer-Rao inequality. We compare the experimental performance of several popular methods with respect to this performance bound, and explain the fundamental tradeoff between variance and bias inherent to the problem of image registration. In particular, we derive and explore the bias of the popular gradient-based estimator showing how widely used multiscale methods for improving performance can be explained with this bias expression. Finally, we present experimental simulations showing the general rule-of-thumb performance limits for gradient-based image registration techniques.