cssi/SciSciGPT-SciSciNet huggingface dataset:
Scaling limits for minimal and random spanning trees in two dimensions

A general formulation is presented for continuum scaling limits of stochastic spanning trees. A spanning tree is expressed in this limit through a consistent collection of subtrees, which includes a tree for every finite set of endpoints in ℝd. Tightness of the distribution, as δ0, is established for the following two-dimensional examples: the uniformly random spanning tree on δℤ2, the minimal spanning tree on δℤ2 (with random edge lengths), and the Euclidean minimal spanning tree on a Poisson process of points in ℝ2 with density δ−2. In each case, sample trees are proven to have the following properties, with probability 1 with respect to any of the limiting measures: (i) there is a single route to infinity (as was known for δ>0); (ii) the tree branches are given by curves which are regular in the sense of Holder continuity; (iii) the branches are also rough, in the sense that their Hausdorff dimension exceeds 1; (iv) there is a random dense subset of ℝ2, of dimension strictly between 1 and 2, on the complement of which (and only there) the spanning subtrees are unique with continuous dependence on the endpoints; (v) branching occurs at countably many points in ℝ2; and (vi) the branching numbers are uniformly bounded. The results include tightness for the loop-erased random walk in two dimensions. The proofs proceed through the derivation of scale-invariant power bounds on the probabilities of repeated crossings of annuli. ©1999 John Wiley & Sons, Inc. Random Struct. Alg., 15, 319–367, 1999
IMAGING SHEAR IN SLIDING CHARGE-DENSITY WAVES BY X-RAY DIFFRACTION TOPOGRAPHY

We have imaged the electric-field-dependent structure of charge-density waves (CDWs) in ribbonlike NbSe3 single crystals by monochromatic x-ray topography. Below the depinning threshold ET the CDW is well correlated. Just above ET , the CDW shears along longitudinal steps in crystal thickness associated with small-angle grain boundaries, and at high fields transverse correlations recover. These results demonstrate x-ray topography as an effective probe of superlattice structure and with earlier transport measurements establish that extrinsic sources dominate CDW plasticity observed in NbSe3.
Anomalous topological pumps and fractional Josephson effects

The authors reveal subtle features in the topological classification of a general class of Hamiltonians, which in turn leads to the discovery of three distinct fractional Josephson effects for superconductors with time-reversal symmetry.
Optimistic Parallelization of Floating-Point Accumulation

Floating-point arithmetic is notoriously nonassociative due to the limited precision representation which demands intermediate values be rounded to fit in the available precision. The resulting cyclic dependency in floating-point accumulation inhibits parallelization of the computation, including efficient use of pipelining. In practice, however, we observe that floating-point operations are "mostly" associative. This observation can be exploited to parallelize floating-point accumulation using a form of optimistic concurrency. In this scheme, we first compute an optimistic associative approximation to the sum and then relax the computation by iteratively propagating errors until the correct sum is obtained. We map this computation to a network of 16 statically-scheduled, pipelined, double-precision floating-point adders on the Virtex-4 LX160 (-12) device where each floating-point adder runs at 296 MHz and has a pipeline depth of 10. On this 16 PE design, we demonstrate an average speedup of 6times with randomly generated data and 3-7times with summations extracted from Conjugate Gradient benchmarks.
Quantum algorithm and circuit design solving the Poisson equation

The Poisson equation occurs in many areas of science and engineering. Here we focus on its numerical solution for an equation in d dimensions. In particular we present a quantum algorithm and a scalable quantum circuit design which approximates the solution of the Poisson equation on a grid with error e. We assume we are given a superposition of function evaluations of the right-hand side of the Poisson equation. The algorithm produces a quantum state encoding the solution. The number of quantum operations and the number of qubits used by the circuit is almost linear in d and polylog in e−1. We present quantum circuit modules together with performance guarantees which can also be used for other problems.
Moderators and Mediators of Treatment Outcome for Youth With ADHD: Understanding for Whom and How Interventions Work

Objective To present data on moderators and mediators of treatment response from the Multimodal Treatment Study of Children With ADHD (MTA). Methods Moderator variables (baseline factors that define subgroups with greater vs lesser intervention response) and mediator variables (factors occurring during treatment that explain how interventions ‘‘work’’) are described with specific application to the outcomes of the MTA Study. Results Key moderator variables (comorbid anxiety disorder, public assistance, severity of attention-deficit/hyperactivity disorder, parental depressive symptomatology, IQ) and mediator processes (negative/ineffective parental discipline) are reviewed. Conclusions Treatment research in the future should explicitly consider the exploration of moderator and mediator variables, which can greatly aid the explanatory power of clinical trials and specify the critical next steps for intervention research.
Seidel–Smith cohomology for tangles

We generalize the “symplectic Khovanov cohomology” of Seidel and Smith (Duke Math J 134(3):453–514, 2006) to tangles using the notion of symplectic valued topological field theory introduced by Wehrheim and Woodward (arXiv:0905.1368).
Maxwell equations and the redundant gauge degree of freedom

On transformation to the Fourier space (k, ω), the partial differential Maxwell equations simplify to algebraic equations, and the Helmholtz theorem of vector calculus reduces to vector algebraic projections. Maxwell equations and their solutions can then be separated readily into longitudinal and transverse components relative to the direction of the wave vector k. The concepts of wave motion, causality, scalar and vector potentials and their gauge transformations in vacuum and in materials can also be discussed from an elementary perspective. In particular, the excessive freedom of choice associated with the gauge dependence of the scalar and the longitudinal vector potentials stands out with clarity in Fourier spaces. Since these potentials are introduced to represent the instantaneous longitudinal electric field, the actual cancellation in the latter of causal contributions arising from these potentials separately in most velocity gauges becomes an important issue. This cancellation is explicitly demonstrated both in the Fourier space, and for pedagogical reasons again in spacetime. The physical origin of the gauge degree of freedom in the masslessness of the photon, the quantum of electromagnetic wave, is elucidated with the help of special relativity and quantum mechanics.
Pay, Reference Points, and Police Performance

Several theories suggest that pay raises below a reference point will reduce job performance. Final offer arbitration for police unions provides a unique opportunity to examine these theories, as the police officers either receive their requested wage or receive a lower one. In the months after New Jersey police officers lose in arbitration, arrest rates and average sentence length decline, and crime reports rise relative to when they win. These declines in performance are larger when the awarded wage is further from the police union's demand. The findings support the idea that considerations of fairness, disappointment, and, more generally, reference points affect workplace behavior.
A biomechanical simulation of the effect of the extrinsic flexor muscles on finger joint flexion

The mechanisms responsible for producing flexion of the metacarpophalangeal (MCP) joints of the fingers remain a matter of debate. Especially, the role of the extrinsic finger flexor muscles has been questioned. Using computer simulation techniques, we sought to determine if it is possible for the extrinsic flexor muscles to produce rotation at all three finger joints and to initiate rotation at the MCP joint. A planar open-link chain with three revolute joints and four links was created to model the index finger. The tendons from the extrinsic flexor muscles were simulated as ropes passing through pulleys. Passive joint stiffness and damping values were obtained from system identification experiments involving the input of angular perturbations to the joint of interest and the measurement of the resulting resistance torque. Simulation output revealed that in the absence of passive joint stiffness and damping, shortening of the extrinsic flexor tendons actually resulted in slight extension of the MCP joint. However, with the inclusion of stiffness and damping, tendon shortening produced simultaneous rotation of all three joints. These results suggest that the extrinsic flexor muscles may play a primary role in controlling MCP flexion.
Black hole entropy in the presence of Chern–Simons terms

We derive a formula for the black hole entropy in theories with gravitational Chern–Simons terms, by generalizing Wald's argument which uses the Noether charge. It correctly reproduces the entropy of three-dimensional black holes in the presence of the Chern–Simons term, which was previously obtained via indirect methods.
The z = 5.8 Quasar SDSSp J1044−0125: A Peek at Quasar Evolution?

The newly discovered z = 5.8 quasar SDSSp J104433.04-012502.2 was recently detected in X-rays and found to be extremely X-ray weak. Here we present the hardness ratio analysis of the XMM-Newton observation. We consider various models to explain the detection in the soft X-ray band and nondetection in the hard band, together with its X-ray weakness. We show that the source may have a steep power-law slope, with an absorber partially covering the continuum. This may be X-ray evidence to support the recent argument of Mathur that narrow-line Seyfert 1 galaxies, which show steep power-law slopes, might be the low-redshift, low-luminosity analogs of the high-redshift quasars. Heavily shrouded and steep X-ray spectrum quasars may indeed represent the early stages of quasar evolution, and SDSSp J104433.04-012502.2 is possibly giving us a first glimpse of the physical evolution of quasar properties.
Accelerating climate and weather simulations through hybrid computing

Unconventional multi- and many-core processors (e.g. IBM (R) Cell B.E.(TM) and NVIDIA (R) GPU) have emerged as effective accelerators in trial climate and weather simulations. Yet these climate and weather models typically run on parallel computers with conventional processors (e.g. Intel, AMD, and IBM) using Message Passing Interface. To address challenges involved in efficiently and easily connecting accelerators to parallel computers, we investigated using IBM's Dynamic Application Virtualization (TM) (IBM DAV) software in a prototype hybrid computing system with representative climate and weather model components. The hybrid system comprises two Intel blades and two IBM QS22 Cell B.E. blades, connected with both InfiniBand(R) (IB) and 1-Gigabit Ethernet. The system significantly accelerates a solar radiation model component by offloading compute-intensive calculations to the Cell blades. Systematic tests show that IBM DAV can seamlessly offload compute-intensive calculations from Intel blades to Cell B.E. blades in a scalable, load-balanced manner. However, noticeable communication overhead was observed, mainly due to IP over the IB protocol. Full utilization of IB Sockets Direct Protocol and the lower latency production version of IBM DAV will reduce this overhead.
A Market for Unbiased Private Data: Paying Individuals According to their Privacy Attitudes

Since there is, in principle, no reason why third parties should not pay individuals for the use of their data, we introduce a realistic market that would allow these payments to be made while taking into account the privacy attitude of the participants. And since it is usually important to use unbiased samples to obtain credible statistical results, we examine the properties that such a market should have and suggest a mechanism that compensates those individuals that participate according to their risk attitudes. Equally important, we show that this mechanism also benefits buyers, as they pay less for the data than they would if they compensated all individuals with the same maximum fee that the most concerned ones expect.
Parallel Array and Mixture-Based Synthetic Combinatorial Chemistry: Tools for the Next Millennium

Technological advances continue to be a central driving force in the acceleration of the drug discovery process. Combinatorial chemistry methods, developed over the past 15 years, represent a paradigm shift in drug discovery. Initially viewed as a curiosity by the pharmaceutical industry, combinatorial chemistry is now recognized as an essential tool that decreases the time of discovery and increases the throughput of chemical screening by as much as 1000-fold. The use of parallel array synthesis approaches and mixture-based combinatorial libraries for drug discovery is reviewed.
Chiral bisphospholane ligands (Me-ketalphos): synthesis of their Rh(I) complexes and applications in asymmetric hydrogenation

Abstract Rhodium complexes of functionalized bisphospholane ligands ( S , S , S , S -Me-ketalphos) 1 and ( R , S , S , R -Me-ketalphos) 2 have been used as catalyst precursors for the asymmetric hydrogenation of several different types of functionalized olefins and have achieved high enantioselectivities.
Exact finite-dimensional nonlinear filters

A new nonlinear filter is derived for continuous-time processes with discrete-time measurements. The filter is exact, and it can be implemented in real time with a computational complexity that is comparable to the Kalman filter. This new filter includes both the Kalman filter and the discrete-time version of the Benes filter as special cases. Moreover, the new theory can handle a large class of nonlinear estimation problems that cannot be solved using the Kalman or discrete-time Benes filters. A simple approximation technique is suggested for practical applications in which the dynamics do not satisfy the required conditions exactly. This approximation is analogous to the so-called "extended Kalman filter" [10], and it represents a generalization of the standard linearization method.
Modified stille coupling utilizing α-iodoenones

Abstract α-Iodoenones undergo Pd-catalyzed coupling with alkenyl- and aryl-tributylstannanes providing an efficient route to the corresponding α-substituted enones.
Legal Socialization of Children and Adolescents

Research on children and the law has recently renewed its focus on the development of children’s ties to law and legal actors. We identify the developmental process through which these relations develop as legal socialization, a process that unfolds during childhood and adolescence as part of a vector of developmental capital that promotes compliance with the law and cooperation with legal actors. In this paper, we show that ties to the law and perceptions of law and legal actors among children and adolescents change over time and age. We show that neighborhood contexts and experiences with legal actors shape the outcomes of legal socialization. Children report lower ratings of legitimacy of the law and greater legal cynicism when they view interactions with legal actors as unfair and harsh. We show that perceived legitimacy of law and legal authorities shapes compliance with the law, and that these effects covary with social contexts including neighborhood. We identify neighborhood differences in this relationship that reflect differential experiences of children with criminal justice authorities and other social control agents. The results suggest that legal actors may play a role in socialization processes that lead to compliance with or rejection of legal and social norms.
Rohrs Examples and Robustness of Simple Adaptive Control

It is well known that arbitrary pole-placement can be obtained when controllers of the same order as the plant to be controlled are used. For this reason, the blame for the failure of low-order adaptive controllers was put on the unmodeled dynamics. This paper reconsiders some well known examples to show that the previous conclusions were too pessimistic, and that low-order adaptive controllers are fit to control the given plants.
Introducing Contemporaneous Open-Outcry and E-Trading at the Chicago Board of Trade

This study uses a vector error correction (VEC) model to examine price-volume relation- ships between open outcry and e-trading at the Chicago Board of Trade. We test whether equilibrium price corrections on one system are independent of the other, and whether this price behavior is more sensitive to changes in screen-based volume as opposed to open outcry volume. Error correction terms capture an asymmetric price adjustment process led by open outcry trading. Open outcry volume (market depth) also results in price discovery by dampening price volatility on both markets. These aspects of market microstructure are relevant in identifying how newly introduced e-trading systems operate in relation to established open outcry systems, and how e-trading systems may affect the economic performance of futures exchanges generally.
The C-17 multifunction display, a building block for avionic systems

The C-17 multifunction display (MFD) has been developed for use as the primary cockpit display system on the US Air Force C-17A military air transport. The 6-inch by 6-inch color cathode ray tube (CRT) display features a self-contained 1750 processor and vector generator (VG) capable of processing MIL-STD-1553B aircraft data and raster video into any of 10 formats as selected by the pilot or copilot. The MFD can display stroke, raster, or hybrid formats in 16 colors. Raster images are driven by sensor inputs with an RS-170 or RS-343 interface. The CRT uses a taut mask delta gun design and provides the best available brightness and line-width performance. Due to its self-contained nature and multiformat capability, reconfigurability in the aircraft is enhanced by using four identical cockpit displays. It is pointed out that its small size, low weight, low power, standard interface, and adaptable software make the C-17 MFD an attractive choice for future avionic upgrades. >
Nursing Students’ Stress Levels, Attitude Toward Drugs, and Drug Use

This study investigated relationships among nursing students’ drug use and two variables usually assumed to contribute to the development of chemical dependency in nurses, i.e., stress and positive attitudes about drugs. Drug use was defined as the use of any psychoactive substance including prescription drugs, over-the-counter drugs, recreational drugs, nicotine, and alcohol. Questionnaires were distributed to senior-year nursing students and a comparison group of seniors in liberal arts. The only significant difference in reported drug use was nursing students’ more frequent use of over-the-counter analgesics. There were no significant differences between nursing and liberal arts majors with regard to three symptoms of stress. Nursing students reported more positive attitudes toward the use of some drugs than peers.
EVALUATION OF LINEAR ASSET PRICING MODELS BY IMPLIED PORTFOLIO PERFORMANCE

Abstract We present a theoretical perspective that motivates the use of the Generalized Least Squares R -Square, prominently advocated by Lewellen et al. [Lewellen, J., Nagel, S., Shanken, J., forthcoming. A skeptical appraisal of asset-pricing tests. Journal of Financial Economics], as an evaluation measure for multivariate linear asset pricing models. Adapting results from Shanken [Shanken, J., 1985. Multivariate tests of the zero-beta CAPM. Journal of Financial Economics 14, 327–348] and Kandel and Stambaugh [Kandel, S., Stambaugh, R.F., 1995. Portfolio inefficiency and the cross-section of expected returns. Journal of Finance 50, 157–184], we provide various interpretations and a graphical account in mean-variance space of this measure, facilitating a better understanding of its properties. We furthermore relate it to another leading evaluation metric, the HJ-distance of Hansen and Jagannathan [Hansen, L.P., Jagannathan, R., 1997. Assessing specification errors in stochastic discount factor models. Journal of Finance 52, 557–590]. Additionally, we present a comparison between these evaluation measures using mean-variance mathematics in risk-return space, and we provide a simple formula for calculating both model evaluation measures that involves only the parameters of the mean-variance asset and factor frontiers.
Taxing Nonrecourse Litigation Funding

ABSTRACT: This article examines the implications of the growing phenomenon of nonrecourse litigation funding. The increasing acceptance and use of such funding raises elemental federal income tax issues of characterization and timing for funding providers and for plaintiffs accepting such funding in exchange for agreeing to share the cash proceeds of any settlement or judgment. Emphasizing the commercial (business-to-business) market for litigation funding as it has evolved, this article addresses the lack of guidance as to the implicit tax compliance issues by testing alternative guidance models that may apply by analogy. It concludes by identifying the single model that should apply and offers a pro forma revenue ruling as a starting point for the government's further consideration of the issues and early promulgation of administrative guidance.
A Morse Index Theorem for Elliptic Operators on Bounded Domains

Given a selfadjoint, elliptic operator L, one would like to know how the spectrum changes as the spatial domain Ω ⊂ ℝ n is deformed. For a family of domains {Ω t } t∈[a, b] we prove that the Morse index of L on Ω a differs from the Morse index of L on Ω b by the Maslov index of a path of Lagrangian subspaces on the boundary of Ω. This is particularly useful when Ω a is a domain for which the Morse index is known, e.g. a region with very small volume. Then the Maslov index computes the difference of Morse indices for the “original” problem (on Ω b ) and the “simplified” problem (on Ω a ). This generalizes previous multi-dimensional Morse index theorems that were only available on star-shaped domains or for Dirichlet boundary conditions. We also discuss how one can compute the Maslov index using crossing forms, and present some applications to the spectral theory of Dirichlet and Neumann boundary value problems.
A substrate-directed synthesis of substituted 2-azaadamantanes

Abstract A synthesis of mono- and disubstituted 2-azaadamantanes with control of substituent stereochemistry has been developed.
Trade and Protection with Multistage Production

This paper analyses trade in manuf acutured goods that are produced via a vertical production structure with many stages, where some value is added at each to an intermediate product to yield a good-in-process ready for the next stage. We consider the stage at which a good is traded to be an economically endogenous variable, with comparative advantage determining the pattern of production specialization by stages across countries. We study how endowment changes and policy shifts move the margin of comparative advantage, which thus provides a channel for resource allocation adjustment that is additional to the usual ones of factor substitution and changes in the quantity of output.
Structure Function Analysis of Long-Term Quasar Variability

In our second paper on long-term quasar variability, we employ a much larger database of quasars than in de Vries, Becker & White. This expanded sample, containing 35,165 quasars from the Sloan Digital Sky Survey (SDSS) Data Release 2 and 6413 additional quasars in the same area of the sky taken from the Two Degree Field (2dF) QSO Redshift Survey, allows us to significantly improve on our earlier conclusions. As before, all the historic quasar photometry has been calibrated onto the SDSS scale by using large numbers of calibration stars around each quasar position. We find the following: (1) The outbursts have an asymmetric light-curve profile, with a fast-rise, slow-decline shape; this argues against a scenario in which microlensing events along the line of sight to the quasars are dominating the long-term variations in quasars. (2) There is no turnover in the structure function of the quasars up to timescales of ~40 yr, and the increase in variability with increasing time lags is monotonic and constant. (3) Consequently, there is not a single preferred characteristic outburst timescale for the quasars, but most likely a continuum of outburst timescales. (4) The magnitude of the quasar variability is a function of wavelength: variability increases toward the blue part of the spectrum. (5) High-luminosity quasars vary less than low-luminosity quasars, consistent with a scenario in which variations have limited absolute magnitude. On this basis, we conclude that quasar variability is intrinsic to the active galactic nucleus and is caused by chromatic outbursts or flares that have limited luminosity range, varying timescales, and an overall asymmetric light-curve shape. Currently, the model that has the most promise of fitting the observations is based on accretion disk instabilities.
Enhanced Angular Momentum Transport in Accretion Disks

▪ Abstract The status of our current understanding of angular momentum transport in accretion disks is reviewed. The last decade has seen a dramatic increase both in the recognition of key physical...
PROMOTIONS, STATE DEPENDENCE AND INTRAFIRM JOB MOBILITY: EVIDENCE FROM PERSONNEL RECORDS ∗

The objective of this paper is to add evidence of job mobility within a firm using personnel records from a single large U.S. corporation, focusing on the determinants of the hazard rates of being promoted to a higher hierarchy level. How to successfully control for unobserved heterogeneity is the goal in this type of analyses, and the approach taken here is to look at the history of the worker, by recognizing state dependence on past promotions. The results show that: (a) the peak of the promotion hazard rates is registered at exactly one year at the current position, even after controlling for observables characteristics and state dependence; (b) males, whites, and more educated workers have a higher probability of being promoted; (c) there is no evidence of “fast tracks”: previous promotions do not imply a higher probability of future promotion, even after controlling for tenure at the current job; and (d) recent new hires seems to have an advantage when competing with insiders for a higher position. These last two findings seem to be at odds with the hypotheses of “job-specific” and “firm-specific” human capital, and to indirectly agree with the “Peter Principle” prediction (Lazear, 2004), which suggests that if workers make efforts beyond their capabilities in order to be promoted, after reaching the desired higher position their incentives to be “over-productive” may decline.
Credit derivatives in banking: Useful tools for managing risk?

Abstract We model the effects on banks of the introduction of a market for credit derivatives; in particular, credit-default swaps. A bank can use such swaps to temporarily transfer credit risks of their loans to others, reducing the likelihood that defaulting loans trigger the bank's financial distress. Because credit derivatives are more flexible at transferring risks than are other, more established tools, such as loan sales without recourse, these instruments make it easier for banks to circumvent the “lemons” problem caused by banks’ superior information about the credit quality of their loans. However, we find that the introduction of a credit-derivatives market is not necessarily desirable because it can cause other markets for loan risk-sharing to break down.
Valuing risks of death from terrorism and natural disasters

This paper uses a random utility model to examine stated preferences for the valuation of public risks of fatalities from terrorist attacks and natural disasters. Traffic-related deaths serve as the common reference point in two series of pairwise risk-risk tradeoff choices. Even after taking into account differences in respondent risk beliefs, the nationally representative sample values the prevention of terrorism deaths almost twice as highly as preventing natural disaster deaths and at about the same level as preventing deaths from traffic accidents, which pose greater personal risk. Education, seatbelt usage, political preferences, and terrorism risk beliefs affect valuations in the expected manner.
CR structures and twisting vacuum spacetimes with two Killing vectors and cosmological constant: type II and more special

Based on the CR formalism of algebraically special spacetimes by Hill, Lewandowski and Nurowski, we derive a nonlinear system of two real ODEs, of which the general solution determines a twisting type II (or more special) vacuum spacetime with two Killing vectors (commuting or not) and at most seven real parameters in addition to the cosmological constant Λ. To demonstrate a broad range of interesting spacetimes that these ODEs can capture, special solutions of various Petrov types are presented and described as they appear in this approach. They include Kerr-NUT, Kerr and Debney/Demianski's type II, Lun's types II and III (subclasses of Held–Robinson), MacCallum and Siklos' type III (Λ < 0) and the type N solutions (Λ ≠ 0) we found in an earlier paper, along with a new class of type II solutions as a nontrivial limit of Kerr and Debney's type II solutions. Also, we discuss a situation in which the two ODEs can be reduced to one. However, constructing the general solution still remains an open problem.
The galactic central diffuse X-ray enhancement : A differential absorption/emission analysis

The soft X-ray background shows a general enhancement toward the inner region of the Galaxy. But whether this enhancement is a local feature (e.g., a superbubble within a distance of 200 pc) and/or a phenomenon related to energetic outflows from the Galactic center/bulge remains unclear. Here we report a comparative X-ray emission and absorption study of diffuse hot gas along the sight lines toward 3C 273 and Mrk 421, on and off the enhancement, but at similar Galactic latitudes. The diffuse 3/4 keV emission intensity, as estimated from the ROSAT All Sky Survey, is about 3 times higher toward 3C 273 than toward Mrk 421. Based on archival Chandra grating observations of these two AGNs, we detect X-ray absorption lines (e.g., O VII Kα, Kβ, and O VIII Kα transitions at z ~ 0) and find that the mean hot gas thermal and kinematic properties along the two sight lines are significantly different. By subtracting the foreground and background contribution, as determined along the Mrk 421 sight line, we isolate the net X-ray absorption and emission produced by the hot gas associated with the enhancement in the direction of 3C 273. From a joint analysis of these differential data sets, we obtain the temperature, dispersion velocity, and hydrogen column density as 2.0(1.6,2.3) × 106 K, 216(104, 480) km s-1, and 2.2(1.4,4.1) × 1019 cm-2, respectively (90% confidence intervals), assuming that the gas is approximately isothermal, solar in metal abundances, and equilibrium in collisional ionization. We also constrain the effective line-of-sight extent of the gas to be 3.4(1.0, 10.1) kpc, strongly suggesting that the enhancement most likely represents a Galactic central phenomenon.
TulaFale: A Security Tool for Web Services

Web services security specifications are typically expressed as a mixture of XML schemas, example messages, and narrative explanations. We propose a new specification language for writing complementary machine-checkable descriptions of SOAP-based security protocols and their properties. Our TulaFale language is based on the pi calculus (for writing collections of SOAP processors running in parallel), plus XML syntax (to express SOAP messaging), logical predicates (to construct and filter SOAP messages), and correspondence assertions (to specify authentication goals of protocols). Our implementation compiles TulaFale into the applied pi calculus, and then runs Blanchet’s resolution-based protocol verifier. Hence, we can automatically verify authentication properties of SOAP protocols.
Reciprocal Trade Agreements: Impacts on Bilateral Trade Expansion and Contraction in the World Agricultural Marketplace

The rapid increase in the number of bilateral and regional free-trade agreements since 1995 is a striking development. The proliferation of these agreements has raised questions about whether they have, in fact, opened markets, created trade, promoted economic growth, and/or distorted trade. This study uses panel data from 1975 to 2005 and a gravity framework model to identify the infl uence of reciprocal trade agreements (RTAs) on bilateral trade in the world agricultural marketplace. A benchmark, Heckman sample-selection and two generalized models, one of which accounts for RTA phase-in effects, are used to gauge the impact on partner trade of mutual as well as asymmetric RTA membership. Empirical results show that RTAs increase agricultural trade between member countries but decrease trade between member and nonmember countries. Interestingly, RTAs were found to be particularly effective at expanding agricultural trade and opening markets in developing countries when developing-country trading partners are part of the same agreement.
Plasmonic angular momentum on metal-dielectric nano-wedges in a sectorial indefinite metamaterial

We present an analytical study in the structure-modulated plasmonic angular momentum, which is trapped in the core region of a sectorial indefinite metamaterial. This metamaterial consists of periodically arranged metal-dielectric nano-wedges along the azimuthal direction. Employing a transfer-matrix calculation and a conformal-mapping technique, our theory can deal with an arbitrary number of wedges with realistically rounded tips. We demonstrate that in the deep-subwavelength regime, strong electric fields that carry large azimuthal variations can exist only within ten-nanometer length scale around the structural center. They are naturally bounded by a characteristic radius on the order of a hundred nanometers from the center. These extreme confining properties suggest that the structure under investigation can be superior to the conventional metal-dielectric cavities in terms of nanoscale photonic manipulation.
Adult Literacy: The Next Generation

~ n 1993,_the first report from the federa!ly funded .National Adult Literacy Survey (NALS), the most comprehensive study of its kind, was released. The good news was that nearly 95% of adult Americans could read at a fourth-grade level or better, showing that illiteracy in its most basic form was relatively low, but the bad news was that nearly half of all adult Americans scored in the lowest two levels of literacy, levels that the National Educational Goals Panel (1994) has stated are well below what American workers need to be competitive in an increasingly global economy. 1 Although these findings shocked public opinion, research showed that it was possible, even likely, that America would continue to fail to achieve a fully literate society. For example, the NALS indicated that nearly 25% of America's adults with an average of 10 years of formal schooling had only fourth-grade literacy skills or lower (Kirsch, Jungeblut, Jenkins, & Kolstad, 1993). In many ethnic minority groups, fewer than 50% of the children complete 10 of the compulsory 12 grades of schooling (National Center on Educational Statistics, 1993a). Low achievement in schools, early dropout from schools, along with the continued flow of poorly educated immigrants, increase the population of adults in need of further skills at least as fast as adult education programs attempt to reduce the size of this group through remediation and retraining. In other words, low-literate 2 Americans may now be seen as a chronic feature of the American educational landscape, with all the well-known statistical relationships with increased children's school failure, lower worker productivity, crime, and welfare. 3 Fortunately, we know considerably more now than we did a decade or even a half decade ago about how to improve literacy in America. 4 This article focuses principally on the 1990s, which have seen a number of new and important studies that can provide guidance for policymakers, practitioners, and researchers in the field of adult literacy. Seven areas, corresponding to key topics in the improvement of adult literacy services, are delineated; in each, we provide a brief analysis of major research findings, followed by a series of recommendations. The article concludes with a synthesis of the recent past and a prognosis for what we believe will be the next generation of adult literacy work in America.
Racial bias in the manager-employee relationship: An analysis of quits, dismissals, and promotions at a large retail firm

Using data from a large U.S. retail firm, we examine how racial matches between managers and their employees affect rates of employee quits, dismissals and promotions. We exploit changes in management at hundreds of stores to estimate hazard models with store fixed effects that control for all unobserved differences across store locations. We find a general pattern of own-race bias across all outcomes in that employees usually have better outcomes when they are the same race as their manager. But we do find anomalies in this pattern, particularly when the manager-employee match violates traditional racial hierarchies (e.g. nonwhites managing whites).
AN EMPIRICAL MODEL OF ACKNOWLEDGMENT FOR SPOKEN-LANGUAGE SYSTEMS

We refine and extend prior views of the description, purposes, and contexts-of-use of acknowledgment acts through empirical examination of the use of acknowledgments in task-based conversation. We distinguish three broad classes of acknowledgments (other←ackn, self←other←ackn, and self+ackn) and present a catalogue of 13 patterns within these classes that account for the specific uses of acknowledgment in the corpus.
Orienting of attention

Bartlett viewed thinking as a high level skill exhibiting ballistic properties that he called its “point of no return”. This paper explores one aspect of cognition through the use of a simple model...
Assessing the substrate selectivities and enantioselectivities of eight novel Baeyer-Villiger monooxygenases toward alkyl-substituted cyclohexanones.

Genes encoding eight Baeyer−Villiger monooxygenases have recently been cloned from bacteria inhabiting a wastewater treatment plant. We have carried out a systematic investigation in which each newly cloned enzyme, as well as the cyclohexanone monooxygenase from Acinetobacter sp. NCIB 9871, was used to oxidize 15 different alkyl-substituted cyclohexanones. The panel of substrates included equal numbers of 2-, 3-, and 4-alkyl-substituted compounds to probe each enzyme's stereoselectivity toward a homologous series of synthetically important compounds. For all 4-alkyl-substituted cyclohexanones tested, enzymes were discovered that afforded each of the corresponding (S)-lactones in ≥98% ee. This was also true for the 2-alkyl-substituted cyclohexanones examined. The situation was more complex for 3-akyl-substituted cyclohexanones. In a few cases, single Baeyer−Villiger monooxygenases possessed both high regio- and enantioselectivities toward these compounds. More commonly, however, they showed only one type o...
Plasma wave terahertz electronics

The oscillation frequencies of the electron density (called plasma waves) in short channel devices correspond to the terahertz (THz) frequency range, and excitation of plasma waves can be used for generating and detecting THz radiation. Plasma wave THz detectors already outperform more conventional THz detectors, but achieving the full potential of plasma wave electronics devices may require use of grating-gate devices and/or plasmonic crystals, which are 2D or 3D arrays of plasmonic FETs.
Design, synthesis and evaluation of near-infrared fluorescent pH indicators in a physiologically relevant range

Removal of a hydroxylsulfonylbutyl arm from indocyanine green dye produced a pH-sensitive near-infrared (NIR) fluorescent indicator that is useful at physiological range.
Effects of artificial excitation upon a low Reynolds number Mach 2.5 jet

The effects of a single point glow discharge excitation device upon a low Reynolds number (8700), Mach 2.5, axisymmetric, cold air jet were experimentally investigated. Both the acoustic and flow fields of the jet were altered by the excitation; the acoustic field could be altered to a greater extent, however, by the addition of a spurious lobe to the sound pressure level contours. It was also possible to reduce the level of excitation so that the acoustic field showed only a slight decrease in the amplitude of the noise radiated by the jet. The main effect of low level excitation was a slight compacting of the development of the jet into a shorter axial length. A decrease in the broadband turbulence, a narrowing of the breadth of the peak in the spectrum around the fundamental frequency, and an enhancement of the harmonics were also noted.
Changing Aspects of Women's Initiation in Southern Africa: An Exploratory Study

RESUMEL'impact de l'initiation feminine a visiblement diminue dans les villes de l'Afrique du Sud. Mes recentes recherches a Lusaka (Zambie) ont cependant montre que ce declin est apparent. Il masque la modification symbolique des rites et assure leur adaptation au milieu urbain. Le chisungu, rite bemba initiant les jeunes femmes aux responsabilites de mariage et de vie adulte, a ete abrege de trois ans a trois jours. Actuellement, il precede directement le mariage lui-meme. Les femmes Cewa et Ngoni habitant la ville ont ete impliquees dans les ceremonies d'initiation bemba, ce que est contraire a la coutume. Cette pratique adapte l'initiation au contexte multiculturel et la ville. Les eglises chretiennes africaines ont elles aussi incorpore les pratiques initiatiques a leurs ceremonies. Cette revitalisation de l'initiation reflete les modifications dans le statut de la femme et exprime symboliquement les nouvelles formes que prend l'identite femine dans les societes pluralistes.
Electromagnetic Scattering From Multilayer Rough Surfaces With Arbitrary Dielectric Profiles for Remote Sensing of Subsurface Soil Moisture

Radar remote sensing of soil moisture content at low frequencies requires an accurate scattering model of realistic soils, which often involves multilayer rough surfaces and dielectric profiles. In this paper, a hybrid analytical/numerical solution to two-dimensional scattering from multilayer rough surfaces separated by arbitrary dielectric profiles based on the extended boundary condition method (EBCM) and scattering matrix technique is presented. The reflection and transmission matrices of rough interfaces are constructed using EBCM. The dielectric profiles are modeled as stacks of piecewise homogeneous dielectric thin layers, whose scattering matrices are computed by recursively cascading reflection and transmission matrices of individual dielectric interfaces. The interactions between the rough interfaces and stratified dielectric profiles are taken into account by applying the generalized scattering matrix technique. The scattering coefficients are obtained by combining the powers computed from the resulting Floquet modes of the overall system. The bistatic scattering coefficients are validated against existing analytical and numerical solutions. Field-collected soil moisture data are then used for numerical simulations to investigate the penetration capability at different frequencies and to address the potential of low-frequency radar systems in estimating deep soil moisture. In particular, soil moisture profiles during dry ground, wet ground, and wet subsurface layer conditions are examined. The results show that both backscattering coefficients and copolarized phase difference at low frequencies are sensitive to the roughness of subsurface interfaces and deep soil moisture. Also, much larger depth sensitivity can be achieved using copolarized phase difference than scattering coefficients
The mild preparation of synthetically useful phosphonic dichlorides: Application to the synthesis of cyclic phosphonic diesters and diamides

Abstract A very mild method for the preparation of synthetically useful phosphonic dichlorides has been developed and its application toward the synthesis of 2-alkyl-2-oxo-1, 3, 2-dioxophosphorinanes and 1, 3-dimethyl-2-alkyl-2-oxo-1, 3, 2-diazaphospholidines is reported.
Fifty Years of Research on the Intelligence of Deaf and Hard-of-Hearing Children: A Review of Literature and Discussion of Implications

In 1965, McCay Vernon drove a stake through the heart of the long-established "truth" that deaf people were inferior to hearing people. Launched by Aristotle, emboldened by the 1880 Conference of Milan, and reiterated in the twentieth century through the biased research of many psychologists, this falsehood persisted until the publication of this classic review paper. Vernon succinctly spotlights biases in IQ assessment of deaf children resulting from improper testing methods, research participant sampling, even the experience level of the evaluators themselves. Brief and scholarly, the paper had enormous impact not only on future research regarding cognition and deaf people but on clinical practice as well. Within this paper, insights are evident which Vernon has continued to elucidate throughout his long career. He was arguably the first psychologist to view the deaf population as a heterogeneous one, noting how various hearing loss etiologies differentially affect cognition and other psychological characteristics. His later research, notably that which focused on rubella, deafblind, and deaf forensic populations, has been similarly pioneering. McCay Vernon's extensive professional impact stems not only from his prolific, readily applied research work but also from his generous and vigorous activities as a teacher, a mentor, and advisor. - Robert Q. Pollard, Jr.
Multiagent Communication Security in Adversarial Settings

In many exciting multiagent applications -- including future battlefields, law enforcement, and commerce -- agents must communicate in inherently or potentially hostile environments in which an adversaries disrupt or intercept the communication between agents for malicious purposes, but the wireless ad hoc networks often proposed for these applications are particularly susceptible to attack. Intelligent agents must balance network performance with possible harm suffered from an adversary's attack, while accounting for the broadcast nature of their communication and heterogenous vulnerabilities of communication links. Furthermore, they must do so when the adversary is also actively and rationally attempting to counter their efforts. We address this challenge in this paper by representing the problem as a game between a sender agent choosing communication paths through a network and an adversary choosing nodes and links to attack. We introduce a network-flow-based approach for compactly representing the competing objectives of network performance and security from adversary attack, and provide a polynomial-time algorithm for finding the equilibrium strategy for the sender. Through empirical evaluation we show how this technique improves upon existing approaches.