cssi/SciSciGPT-SciSciNet huggingface dataset:
Selective principal component extraction and reconstruction: a novel method for ground based exoplanet spectroscopy

Context. Infrared spectroscopy of primary and secondary eclipse events probes the composition of exoplanet atmospheres and, using space telescopes, has detected H2O, CH4 and CO2 in three hot Jupiters. However, the available data from space telescopes has limited spectral resolution and does not cover the 2.4−5.2 μm spectral region. While large ground based telescopes have the potential to obtain molecular-abundance-grade spectra for many exoplanets, realizing this potential requires retrieving the astrophysical signal in the presence of large Earth-atmospheric and instrument systematic errors. Aims. Here we report a wavelet-assisted, selective principal component extraction method for ground based retrieval of the dayside spectrum of HD189733b from data containing systematic errors. Methods. The method uses singular value decomposition and extracts those critical points of the Rayleigh quotient which correspond to the planet induced signal. The method does not require prior knowledge of the planet spectrum or the physical mechanisms causing systematic errors. Results. The spectrum obtained with our method is in excellent agreement with space based measurements made with HST and Spitzer and confirms the recent ground based measurements including the strong ∼3.3 μm emission.
Using dual approximation algorithms for scheduling problems theoretical and practical results

The problem of scheduling a set of n jobs on m identical machines so as to minimize the makespan time is perhaps the most well-studied problem in the theory of approximation algorithms for NP-hard optimization problems. In this paper the strongest possible type of result for this problem, a polynomial approximation scheme, is presented. More precisely, for each e, an algorithm that runs in time O((n/e)1/e2) and has relative error at most e is given. In addition, more practical algorithms for e = 1/5 + 2-k and e = 1/6 + 2-k, which have running times O(n(k + log n)) and O(n(km4 + log n)) are presented. The techniques of analysis used in proving these results are extremely simple, especially in comparison with the baroque weighting techniques used previously.The scheme is based on a new approach to constructing approximation algorithms, which is called dual approximation algorithms, where the aim is to find superoptimal, but infeasible, solutions, and the performance is measured by the degree of infeasibility allowed. This notion should find wide applicability in its own right and should be considered for any optimization problem where traditional approximation algorithms have been particularly elusive.
Utilitarian and modern: clientelism, citizen empowerment, and civic engagement in the Arab world

In this article, we examine the patterns of civic engagement in non-democratic and democratizing polities of the Arab world. The theoretical argument incorporates two perspectives: modernization theory and utilitarianism. Specifically, we use wasta-seeking behaviour and indicators of human capital and citizen empowerment to explain the micro-level foundations of civic engagement. We build on the implications of these approaches to explain the civic gender gap and women's status in Arab societies. The results of a series of multivariate estimations using the first wave of the Arab Barometer Survey show that clientelistic behaviour along with higher levels of education and employment status explain citizens' involvement in various forms of civic activities. We argue that the former helps sustain traditional authoritarian structures and the latter may help democratization by strengthening civil society. We also detect a civic gender gap and find that citizen empowerment and modernization may narrow this gap ...
GALACTIC OUTFLOWS AND PHOTOIONIZATION HEATING IN THE REIONIZATION EPOCH

We carry out a new suite of cosmological radiation hydrodynamic simulations that explores the relative impacts on reionization-epoch star formation of galactic outflows and photoionization heating from a self-consistently grown extragalactic ultraviolet ionizing background (EUVB). We compare the predictions with observational constraints from the cosmic microwave background, the ultraviolet continuum luminosity function of galaxies, and the Ly? forest. By itself, an EUVB suppresses the luminosity function by less than 50% at z = 6 even if it is orders of magnitude stronger than observed. This overproduces the observed galaxy abundance by a factor of 3-5, indicating the need for an additional feedback process. We confirm that outflows readily suppress both the EUVB and the luminosity function into improved agreement with observations. Population I-II star formation can reionize the universe by z = 6 even in the presence of strong feedback from photoheating and outflows. The resulting EUVB suppresses star formation in halos with virial temperatures below 105?K but has a weaker impact on more massive halos. Nonetheless, halos with virial temperatures below 105?K contribute up to ~50% of all ionizing photons owing to the EUVB's inhomogeneity. Overall, star formation rate scales with halo mass Mh as M 1.3-1.4 h for halos with Mh = 108.2-1010.2 M ?. This is a steeper dependence than is often assumed in reionization models, boosting the expected power spectrum of 21 centimeter fluctuations on large scales. The luminosity function rises steeply to at least M 1600 = ?13 even in models that treat both outflows and an EUVB, indicating that reionization was driven by faint galaxies (M 1600 ? ?15) that have not yet been observed. Outflows and an EUVB interfere with each other's feedback effects in two ways. Outflows weaken the EUVB, limiting Jeans suppression of low-mass halos; this leads to overall de-amplification of suppression at early times (z > 8). Meanwhile, they amplify each other's impact on more massive halos, leading to overall amplification of suppression at later times. Our models cannot simultaneously explain observations of galaxies, the cosmic microwave background, and the intergalactic medium. Correcting for dynamic range limitations and adjusting our physical treatments will alleviate discrepancies, but observations may still require additional physical scalings such as a mass-dependent ionizing escape fraction.
A note on parabolic subgroups of a Coxeter group

Abstract The aim of this note is to prove that the parabolic closure of any subset of a Coxeter group is a parabolic subgroup. To obtain that, several technical lemmas on the root system of a parabolic subgroup are established.
Linear feature extraction and description

Abstract A technique of edge detection and line finding for linear feature extraction is described. Edge detection is by convolution with small edge-like masks. The resulting output is thinned and linked by using edge positions and orientations and approximated by piecewise linear segments. Some linear features, e.g., roads and airport runways, are suitably described by “antiparallel” pairs of linear segments. Experimental results on aerial images are presented.
Counting faces of cubical spheres modulo two

Abstract Several recent papers have addressed the problem of characterizing the f-vectors of cubical polytopes. This is largely motivated by the complete characterization of the f-vectors of simplicial polytopes given by Stanley (Discrete Geometry and Convexity, Annals of the New York Academy of Sciences, Vol. 440, 1985, pp. 212–223) and Billera and Lee (Bull. Amer. Math. Soc. 2 (1980) 181–185) in 1980. Along these lines Blind and Blind (Discrete Comput. Geom. 11(3) (1994) 351–356) have shown that unlike in the simplicial case, there are parity restrictions on the f-vectors of cubical polytopes. In particular, except for polygons, all even dimensional cubical polytopes must have an even number of vertices. Here this result is extended to a class of zonotopal complexes which includes simply connected odd dimensional manifolds. This paper then shows that the only modular equations which hold for the f-vectors of all d-dimensional cubical polytopes (and hence spheres) are modulo two. Finally, the question of which mod two equations hold for the f-vectors of PL cubical spheres is reduced to a question about the Euler characteristics of multiple point loci from codimension one PL immersions into the d-sphere. Some results about this topological question are known (Eccles, Lecture Notes in Mathematics, Vol. 788, Springer, Berlin, 1980, pp. 23–38; Herbert, Mem. Amer. Math. Soc. 34 (250) (1981); Lannes, Lecture Notes in Mathematics, Vol. 1051, Springer, Berlin, 1984, pp. 263–270) and Herbert's result we translate into the cubical setting, thereby removing the PL requirement. A central definition in this paper is that of the derivative complex, which captures the correspondence between cubical spheres and codimension one immersions.
Constructing symplectic forms on 4-manifolds which vanish on circles

Given a smooth, closed, oriented 4-manifold X and α ∈ H2(X, Z) such that α � α > 0, a closed 2-form ω is constructed, Poincare dual to α, which is symplectic on the complement of a finite set of unknotted circles Z. The number of circles, counted with sign, is given by d = (c1(s) 2 −3σ(X)−2χ(X))/4, where s is a certain spin C structure naturally associated to ω.
Identifying quality-requirement conflicts

One of the biggest risks in software requirements engineering is the risk of overemphasizing one quality attribute requirement (e.g., performance) at the expense of others at least as important (e.g., evolvability and portability). The paper describes an exploratory knowledge based tool for identifying potential conflicts among quality attributes early in the software/ system life cycle. The Quality Attribute Risk and Conflict Consultant (QARCC) examines the quality attribute tradeoffs involved in software architecture and process strategies. It operates in the context of the USC CSE WinWin system, a groupware support system for determining software and system requirements as negotiated win conditions. We have developed and experimented with an initial QARCC 1 prototype. We are using the results of the experiment to develop an improved QARCC 2 tool. From our initial experimentation, we concluded that QARCC can alert users, developers, customers, and other stakeholders to conflicts among their software quality requirements and can help them identify additional, potentially important quality requirements. We also concluded that QARCC needs further refinement to avoid overloading users with insignificant quality conflict suggestions. We are now refining the knowledge base to address more detailed quality attributes in a more selective fashion.
Completeness of Determinantal Hamiltonian Flows on the Matrix Affine Poisson Space

The matrix affine Poisson space (Mm,n ,π m,n) is the space of complex rect- angular matrices equipped with a canonical quadratic Poisson structure which in the square case m = n reduces to the standard Poisson structure on GLn(C) .W e prove that the Hamiltonian flows of all minors are complete. As a corollary we obtain that all Kogan-Zelevinsky integrable systems on Mn,n are complete and thus induce (analytic) Hamiltonian actions of C n(n−1)/2 on (Mn,n ,π n,n) (as well as on GL n(C) and on SLn(C)). We define Gelfand-Zeitlin integrable systems on (Mn,n ,π n,n) from chains of Poisson pro- jections and prove that their flows are also complete. This is an analog for the quadratic Poisson structure πn,n of the recent result of Kostant and Wallach (Studies in Lie Theory. Progress in Mathematics, vol 243, pp 319-364. BirkhBoston, 2006) that the flows of the complexified classical Gelfand-Zeitlin integrable systems are complete.
Function Fields with Class Number Indivisible by a Prime $\ell$

It is known that innitely many number elds and function m over Fq(T ) with class number indivisible by an arbitrary prime '. We give an explicit description of those primes (and prime powers) q for which the result holds. For the special case where ' = 3 and m = 2, we recover Ichimura's result.
A quantum phase transition in a quantum external field: superposing two magnetic phases.

We study an Ising chain undergoing a quantum phase transition in a quantum magnetic field. Such a field can be emulated by coupling the chain to a central spin initially in a superposition state. We show that – by adiabatically driving such a system – one can prepare a quantum superposition of any two ground states of the Ising chain. In particular, one can end up with the Ising chain in a superposition of ferromagnetic and paramagnetic phases – a scenario with no analogue in prior studies of quantum phase transitions. Remarkably, the resulting magnetization of the chain encodes the position of the critical point and universal critical exponents, as well as the ground state fidelity.
Optimal robust fault detection for linear discrete time systems

This paper considers robust fault-detection problems for linear discrete time systems. It is shown that the optimal robust detection filters for several well-recognized robust fault-detection problems, such as H-/H∞, H2/H∞, and H∞/H∞ problems, are the same and can be obtained by solving a standard algebraic Riccati equation. Optimal filters are also derived for many other optimization criteria and it is shown that some well-studied and seeming-sensible optimization criteria for fault-detection filter design could lead to (optimal) but useless fault-detection filters.
The ideal source of local public revenue

Free or underpriced curb parking creates a classic commons problem. Studies have found that between 8% and 74% of cars in congested traffic were cruising in search of curb parking, and that the average time to find a curb space ranged between 3 and 14 min. Cities can eliminate the economic incentive to cruise by charging market-clearing prices for curb parking spaces. Market-priced curb parking can yield between 5% and 8% of the total land rent in a city, and in some neighborhoods can yield more revenue than the property tax.
The road from animal electricity to green energy: combining experiment and theory in electrocatalysis

Advances in the field of electrocatalysis over the past several decades have been driven both by improvements in fundamental techniques for probing the solid–liquid electrochemical interface and by the technological imperative to develop enhanced low temperature electrocatalytic devices. In this review, we describe how a synergistic interaction between fundamental science and technological progress has resulted in both the emergence of greatly enhanced understanding of electrocatalytic systems and the development of practically improved electrocatalysts. Since it is not possible to summarize in detail all relevant developments in this broad field in such a brief space, we focus selectively on the early historical development of the field and on the use of trends-based analyses to describe the properties of electrocatalytic materials in terms of relatively simple catalytic properties, or descriptors. We begin by discussing aspects of the historical development of “reversible fuel cells” in acidic media, including topics relevant both to fuel cells, wherein hydrogen and oxygen are converted to water with concomitant production of electricity (electrons), and to electrolyzers, wherein electrons are used to initiate water splitting to yield hydrogen and oxygen. We then show how this development has stimulated the development of in situ and ex situ surface sensitive probes and spectroscopic methods capable of elucidating fundamental (atomic-/molecular-level) chemical and electronic properties of electrode–electrolyte interfaces. We further discuss how enhanced computational approaches, that can accurately calculate covalent bonding interactions in these systems, have contributed to the growth of a synergistic experimental/computational approach to electrochemical surface science that has resulted in a highly successful paradigm for the understanding of reactivity trends across a space of different metals, alloys, and metal oxides; this work, in turn, has spurred the development of alternative energy systems for efficient conversion and storage of chemical energy. We conclude with a discussion of some further needs for methodological developments and future research directions.
Delay-Limited Cooperative Communication With Reliability Constraints in Wireless Networks

We investigate optimal resource allocation for delay-limited cooperative communication in time varying wireless networks. Motivated by real-time applications that have stringent delay constraints, we develop a dynamic cooperation strategy that makes optimal use of network resources to achieve a target outage probability (reliability) for each user subject to average power constraints. Using the technique of Lyapunov optimization, we first present a general framework to solve this problem and then derive quasi-closed form solutions for several cooperative protocols proposed in the literature. Unlike earlier works, our scheme does not require prior knowledge of the statistical description of the packet arrival, channel state, and node mobility processes and can be implemented in an online fashion.
Navier-Stokes analysis of turbine flowfield and external heat transfer

An explicit two-dimensional Navier-Stokes code has been modified and used to analyze the aerodynamics and heat transfer of a transonic turbine cascade. This code is based on a four-stage Runge—Kutta scheme. An algebraic Reynolds stress model (ARSM) and two versions of low Reynolds number two-equation turbulence models have been employed in the computation. Detailed comparisons are made between the predictions and the data measured by Arts et al. at the von Karman Institute. An evaluation of the performance of different turbulence models for turbine aerodynamics and heat transfer has been carried out. The surface pressure distributions and wake profiles are predicted well by all the models. Reasonably good predictions have been obtained for the blade heat transfer by the k-e and the ^-e/ARSM models. The A>e/ARSM model appears to be able to capture, qualitatively, the anisotropy associated with bypass transition. A boundary-layer code was also used to predict heat transfer for comparison with the elliptic Navier—Stokes solutions.
Directed Nickel-Catalyzed Negishi Cross Coupling of Alkyl Aziridines

Herein we report a nickel-catalyzed C–C bond-forming reaction between simple alkyl aziridines and organozinc reagents. This method represents the first catalytic cross-coupling reaction employing a nonallylic and nonbenzylic Csp3–N bond as an electrophile. Key to its success is the use of a new N-protecting group (cinsyl or Cn) bearing an electron-deficient olefin that directs oxidative addition and facilitates reductive elimination. Studies pertinent to elucidation of the mechanism of cross coupling are also presented.
Dominance of magnetic cataclysmic variables in the resolved Galactic ridge X‐ray emission of the limiting window

The diffuse appearance of the Galactic ridge X-ray emission has been puzzling since its discovery due to the lack of compelling theories for sustainable hot diffuse X-ray emission in the Galactic plane. Recently, Revnivtsev et al. claimed that ∼90 per cent of the 6.5–7.1 keV X-ray flux from a small section of a low-extinction region at 1°.4 south of the Galactic Centre has been resolved to discrete sources with erg s−1 cm−2, using ultradeep (1 Ms) observations made by the Chandra X-ray Observatory. They also concluded that coronally active stars such as active binaries (ABs) contribute ∼60 per cent of the resolved flux. However, our recent discovery of a large population of magnetic cataclysmic variables (MCVs) in the same region suggests their significant role in the resolved hard X-ray flux. In addition, deep X-ray surveys of other several Galactic bulge fields over the past decade have indicated that MCVs are likely the major contributor in the hard X-ray emission above 2–3 keV. To solve this mystery, we have conducted an independent in-depth analysis of discrete X-ray sources in the low-extinction region. The total fraction of the 6.5–7.1 keV flux we can confidently claim as resolved is ∼70–80 per cent, which largely agrees with Revnivtsev et al., but leaves some room for diffuse components. However, despite the various attempts, we consistently find that the resolved hard X-ray flux above 3 keV is dominated by relatively bright, hard X-ray sources such as MCVs, whereas the contribution from relatively faint, soft sources such as ABs is below 20 per cent. We describe in detail our analysis procedure in order to elucidate possible origins of the discrepancy.
Measurement noise error bounds for eigensystem realization algorithm

This paper studies the identification of linear discrete-time time-invariant finite-dimensional systems using Markov parameters. It is shown that the eigensystem realisation algorithm (ERA) and Ho-Kalman realizations are special cases of a more general construction for obtaining minimal realizations from decompositions of the Markov block Hankel matrix. An upper bound for the error between the system and the reduced-order model formed from truncation of the ERA realization of the noisy Markov block Handel matrix is given. Finally, numerical computation of this new upper bound are given to illustrate these results.
Shape and color conjunction stimuli are represented as bound objects in visual working memory.

Abstract The integrated object view of visual working memory (WM) argues that objects (rather than features) are the building block of visual WM, so that adding an extra feature to an object does not result in any extra cost to WM capacity. Alternative views have shown that complex objects consume additional WM storage capacity so that it may not be represented as bound objects. Additionally, it was argued that two features from the same dimension (i.e., color–color) do not form an integrated object in visual WM. This led some to argue for a “weak” object view of visual WM. We used the contralateral delay activity (the CDA) as an electrophysiological marker of WM capacity, to test those alternative hypotheses to the integrated object account. In two experiments we presented complex stimuli and color–color conjunction stimuli, and compared performance in displays that had one object but varying degrees of feature complexity. The results supported the integrated object account by showing that the CDA amplitude corresponded to the number of objects regardless of the number of features within each object, even for complex objects or color–color conjunction stimuli.
Wavelet analysis for EEG feature extraction in deception detection

Deception detection has important clinical and legal implications. However, the reliability of methods for the discrimination between truthful and deceptive responses is still limited. Efforts to improve reliability have examined measures of central nervous system function such as EEG. However, EEG analyses based on either time- or frequency-domain parameters have had mixed results. Because EEG is a nonstationary signal, the use of joint time-frequency features may yield more reliable results for detecting deception. The goal of this study was to investigate the feasibility of deception detection based on EEG features extracted through wavelet transformation. EEG was recorded from 4 electrode sites (F3, F4, F7, F8) during a modified version of the Guilty Knowledge Test (GKT) in 5 subjects. Wavelet analysis revealed significant differences between deceptive and truthful responses. These differences were detected in features whose frequency range roughly corresponds to the EEG beta rhythm and within a time window which coincides with the P300 component. These preliminary results indicate that joint time-frequency EEG features extracted through wavelet analysis may provide a more reliable method for detecting deception than standard ERPs.
Coronary bypass grafting with totally calcified or acutely dissected ascending aorta.

Abstract From August 1984 through November 1988, 10 of 2,658 patients undergoing coronary artery bypass grafting had ascending aortic disease that was not amenable to proximal anastomoses for coronary bypass grafting. This was due to a calcified aorta in 6 and acute aortic dissection in 4. There were 5 male and 5 female patients with a mean age of 71 years. Cannulation site was the femoral artery in 5, ascending aorta in 3, and aortic arch in 2. Profound hypothermia and ventricular fibrillation, with no crossclamp or cardioplegia, was used in 9 patients, and circulatory arrest in 1. In 8 patients a single internal mammary artery was used as the total inflow with a saphenous vein graft brought off the internal mammary artery to one or more distal left-sided coronary vessels. Bilateral internal mammary arteries were used in 2 other patients. Operative mortality was zero. There was one perioperative myocardial infarction and one transient stroke without sequelae. All patients have done well from 1 to 6 years postoperatively. These data support the use of internal mammary arteries as single or bilateral proximal conduits for other venoarterial bypass grafts when the aorta is extensively diseased either by calcification or dissection.
Energy-efficient scheduling of delay constrained traffic over fading channels

A delay-constrained scheduling problem for point-to-point communication is considered: a packet of B bits must be transmitted by a hard deadline of T slots over a time-varying channel. The transmitter/scheduler must determine how many bits to transmit, or equivalently how much energy to transmit with, during each time slot based on the current channel quality and the number of unserved bits, with the objective of minimizing expected total energy. In order to focus on the fundamental scheduling problem, it is assumed that no other packets are scheduled during this time period and no outage is allowed. Assuming transmission at capacity of the underlying Gaussian noise channel, a closed-form expression for the optimal scheduling policy is obtained for the case T = 2 via dynamic programming; for T > 2, the optimal policy can only be numerically determined. Thus, the focus of the work is on derivation of simple, near-optimal policies based on intuition from the T = 2 solution and the structure of the general problem. The proposed bit-allocation policies consist of a linear combination of a delay-associated term and an opportunistic (channel-aware) term. In addition, a variation of the problem in which the entire packet must be transmitted in a single slot is studied, and a channel-threshold policy is shown to be optimal.
Monitored Mobility in the Era of Mass Customization

Just as Web browsers use information about surfing habits to customize content and advertising, so the development of mobile commerce (m-commerce) promises to capitalize on the real-time monitoring of the time-space paths followed by consumers. Thanks to the development of wireless, networked devices, gathering detailed information about consumer mobility is becoming increasingly cheap and efficient. The result is that spaces associated with leisure and domesticity can become increasingly economically productive insofar as consumers are subjected to comprehensive monitoring in exchange for the promise of customization and individuation. Drawing on examples from e-commerce and popular culture, this article explores the connection between the consumption of space and the incitement to mobility, arguing that the mass customized economy represents a continuation of the logic of market rationalization in the network era.
Financial Development and Real Price Level Differences

Real price levels are systematically lower in developing countries than in developed countries. This paper provides time series evidence about the effect of financial development on real price level differences for 40 developing countries. Based on cointegration tests, a long-run equilibrium relationship is found between financial development and real price level differences in 21 countries. In seven countries, financial development “Granger-causes” real price level differentials, while for 19 countries the causality runs in the opposite direction. Country-specific institutional or political-economy differences, typically ignored in crosssection analysis, likely play an important role in real price level differences.
Quantum Philosophy: The Flight from Reason in Science

We want to pause and comment on a rather delicate matter concerning a notoriously difficult subject, the foundations of quantum mechanics, a subject that has inspired a great many peculiar proclamations.
Cell Division Resets Polarity and Motility for the Bacterium Myxococcus xanthus

ABSTRACT Links between cell division and other cellular processes are poorly understood. It is difficult to simultaneously examine division and function in most cell types. Most of the research probing aspects of cell division has experimented with stationary or immobilized cells or distinctly asymmetrical cells. Here we took an alternative approach by examining cell division events within motile groups of cells growing on solid medium by time-lapse microscopy. A total of 558 cell divisions were identified among approximately 12,000 cells. We found an interconnection of division, motility, and polarity in the bacterium Myxococcus xanthus. For every division event, motile cells stop moving to divide. Progeny cells of binary fission subsequently move in opposing directions. This behavior involves M. xanthus Frz proteins that regulate M. xanthus motility reversals but is independent of type IV pilus “S motility.” The inheritance of opposing polarity is correlated with the distribution of the G protein RomR within these dividing cells. The constriction at the point of division limits the intracellular distribution of RomR. Thus, the asymmetric distribution of RomR at the parent cell poles becomes mirrored at new poles initiated at the site of division.
A low on resistance 700V charge balanced LDMOS with intersected WELL structure

A new 700V rate charge balanced LDMOS structure is proposed. The key feature of this structure is the intersected N-Well and P-Well that divides drift region into multi parallel conduction path. Ron,sp can be reduced by considerably high doped N-Well region and surface electric field can be dispersed by each Well junction. Ron,sp of the proposed LDMOS is reduced by 55% compared with conventional LDMOS. This value nearly gets to the limit of LDMOS made by bulk silicon. The surface electric field that can cause fatal failure of LDMOS in reliability characteristics is decreased by 30% compared with conventional LDMOS. The position occurring breakdown was moved from surface to bulk below drain contact in the proposed LDMOS.
Users’ Guides to the Medical Literature: A Manual for Evidence-Based Clinical Practice

Guyatt G, Rennie D. Users’ Guides to the Medical Literature: A Manual for Evidence-Based Clinical Practice. Chicago: American Medical Association, 2001. Since its introduction in JAMA in 1993, the Users’ Guides to the Medical Literature article series has become the standard for understanding and using the medical literature in daily practice. This series of 25 articles clarifies the principles of evidence-based medicine, and provides clear and practical guides for accessing and evaluating articles published in the medical literature. Users’ Guides to the Medical Literature: A Manual for Evidence-Based Clinical Practice is not only a compilation of the users’ guides from the JAMA series; it also modifies, expands, and updates the original articles. Rennie’s insightful analogy in the foreword of the book states that the medical literature is “clearly visible but utterly inaccessible”, a message that serves as an honest appraisal of the difficulties faced by clinicians who are attempting to go …
Concurrent Sample Path Analysis of Discrete Event Systems

The sample path constructability problem for Discrete Event Systems (DES) involves the observation of a sample path under a particular parameter value \theta of the system with the requirement to concurrently construct multiple sample paths of the DES under different values using only information available along the given sample path. This allows the on-line estimation of performance measures J(\theta), not available in closed form, over a range of values of \theta. We present a sample path coupling approach that solves the problem without imposing any restrictions on the event processes in the system. A specific ’’time warping‘‘ algorithm is described and its performance is analyzed in terms of computational cost. Our approach is illustrated through a number of simulation results.
Nonuniform image motion estimation using Kalman filtering

This correspondence presents a new pixel-recursive algorithm for estimating the nonuniform image motion from noisy measurements. The proposed method is performed in two steps. First, the pixels are examined to identify the (detectable) moving pixels, using a binary hypothesis testing. Then, characterizing the motion of the identified moving pixels in terms of a unitary transformation, the motion coefficients are estimated using a Kalman filter. Because the motion vector is typically (spatially) slowly varying, the size of the motion coefficient vector is significantly reduced. Consequently, the proposed Kalman filter need only search for the truncated coefficients of the motion field. The proposed method is simulated on a computer, and results are compared with the algorithm reported by Netravali and Robbins (see Bell Syst. Tech. J. vol.58, no.3, p.631-70, Mar. 1979). >
A modular description of the K(2)-local sphere at the prime 3

Using degree N isogenies of elliptic curves, we produce a spectrum Q(N). This spectrum is built out of spectra related to tmf. At p = 3 we show that the K(2)local sphere is built out of Q(2) and its K(2)-local Spanier-Whitehead dual. This gives a conceptual reinterpretation a resolution of Goerss, Henn, Mahowald, and Rezk. AMS classic ation: Primary 55Q40, 55Q51, 55N34. Secondary 55S05, 14H52.
Decentralization and Political Control of the Bureaucracy

In contrast to principal-agency theory, the possibility of the political control of the bureaucracy depends on bureaucratic structure. In this article, I argue that the functional decentralization of responsibility and authority for policy formulation and implementation involves a net loss of political control. I show that the choice by the Nuclear Regulatory Commission (NRC) to transfer responsibility to its Regional Offices changed the ability of national political superiors to intervene in policy implementation in the field. Examining Regional Office data on the enforcement of reactor regulations from 1975 to 1996, I present statistical tests of the changing influence of national political institutions, local policy preferences, and the Regions’ task environment. I find that decentralization insulated the NRC from national political oversight, and that the Regions were more responsive to local oversight postdevolution and deviated from a ‘natural rate’ of enforcement.
Enhancing perceived depth in images via artistic matting

We present an algorithm for the addition of artistic mattes to digital images for the purpose of enhancing the sense of depth in the image. We provide examples exploring color and double mattes as well as report the results from a perception study which may indicate an increase in perceived depth in matted imagery.
How bad is selfish routing

We consider the problem of routing traffic to optimize the performance of a congested network. We are given a network, a rate of traffic between each pair of nodes, and a latency function for each edge specifying the time needed to traverse the edge given its congestion; the objective is to route traffic such that the sum of all travel times---the total latency---is minimized.In many settings, it may be expensive or impossible to regulate network traffic so as to implement an optimal assignment of routes. In the absence of regulation by some central authority, we assume that each network user routes its traffic on the minimum-latency path available to it, given the network congestion caused by the other users. In general such a "selfishly motivated" assignment of traffic to paths will not minimize the total latency; hence, this lack of regulation carries the cost of decreased network performance.In this article, we quantify the degradation in network performance due to unregulated traffic. We prove that if the latency of each edge is a linear function of its congestion, then the total latency of the routes chosen by selfish network users is at most 4/3 times the minimum possible total latency (subject to the condition that all traffic must be routed). We also consider the more general setting in which edge latency functions are assumed only to be continuous and nondecreasing in the edge congestion. Here, the total latency of the routes chosen by unregulated selfish network users may be arbitrarily larger than the minimum possible total latency; however, we prove that it is no more than the total latency incurred by optimally routing twice as much traffic.
Catalytic asymmetric C-H activation by methyl thiophen-3-yldiazoacetate applied to the synthesis of (+)-cetiedil

Abstract Dirhodium tetraprolinate catalyzed reaction of methyl thiophen-3-yldiazoacetate results in intermolecular allylic C–H activation by means of rhodium carbenoid induced C–H insertion. The reaction with 1,4-cyclohexadiene was applied to the asymmetric synthesis of (+)-cetiedil.
Enantioselective Nazarov Reactions through Catalytic Asymmetric Proton Transfer

The development of catalytic asymmetric Nazarov reactions that require only 10 mol % of chiral Lewis acid and proceed with ee's between 72% and 97% is described.
Two geometric character formulas for reductive Lie groups

In this paper we prove two formulas for the characters of representations of reductive groups. Both express the character of a representation π in terms of the same geometric data attached to π. When specialized to the case of a compact Lie group, one of them reduces to Kirillov’s character formula in the compact case, and the other, to an application of the Atiyah-Bott fixed point formula to the Borel-Weil realization of the representation π. To set the stage, let us first recall the Borel-Weil theorem for a connected, compact Lie group GR. For simplicity, we assume that GR is simply connected. We let gR denote its Lie algebra and g = C ⊗R gR the complexified Lie algebra. Via the adjoint action, GR operates on igR∗, the space of all R-linear functions λ : gR → iR. Every GR-orbit Ω in igR∗ – “coadjoint orbit” for short – carries a canonical GRinvariant symplectic structure. The orbit Ω is said to be integral if some, or equivalently any, λ ∈ Ω exponentiates to a character e of the isotropy subgroup (GR)λ. In that case, the one-dimensional representation spaces of the characters e, λ ∈ Ω, fit together into a GR-equivariant, real algebraic, Hermitian line bundle LΩ → Ω. The pair (Ω,LΩ → Ω) carries a unique “positive polarization”: a GR-invariant complex structure on the manifold Ω and the structure of a GR-equivariant holomorphic line bundle on LΩ, positive in the sense of algebraic geometry. The hypothesis of simple connectivity ensures that the square root √ KΩ of the canonical bundle KΩ exists as a GR-equivariant holomorphic line bundle. According to the Borel-Weil theorem, the natural action of GR on the space of holomorphic LΩ-valued half forms H0(Ω,O(K Ω ⊗ LΩ)) is irreducible; moreover, the association Ω H0(Ω,O(K Ω ⊗ LΩ)) (1.1)
Alternative paths to structural adjustment in Uzbekistan in a three-gap framework

The author presents an internally consistent macroeconomic framework that could be used as a first step toward a more comprehensive, quantitative and qualitative assessment of the adjustment alternatives facing Uzbekistan. The three-gap framework focuses on the major imbalances of the economy for evaluating policy choices facing Uzbekistan. It emphasizes the domestic, and external factors that determine economic outcomes, and welfare. The author attempts to quantify two policy scenarios-gradual as against an accelerated policy implementation strategy. He finds that an aggressive adjustment policy would indeed improve most performance, and welfare indicators. Two major ingredients of such an aggressive adjustment strategy are the unification of the exchange rate, and implementation of current account convertibility in the balance of payments. The author also draws attention to the relative importance of external financing, and the sustainability of the balance of payments under alternative structural adjustment paths facing Uzbekistan.
Outside directors and board advising and monitoring performance

Abstract Divergent views exist about whether boards must tradeoff advising for monitoring performance when utilizing outside versus inside directors. We suggest a dichotomous tradeoff focus underestimates outside directors׳ impact on board performance. We find outside director tenure positively associated with firm acquisition/investment policy advising performance and CEO compensation monitoring performance, suggesting that advising and monitoring do not always compete for directors׳ time. However, tenure is not a panacea – it marginally weakens financial reporting monitoring performance which is instead enhanced by outside directors׳ financial expertise. Overall, the results suggest outside director tenure and diverse expertise support both advising and monitoring performance.
Experiment and Theory in Computations of the He Atom Ground State

Extensive variational computations are reported for the ground state energy of the nonrelativistic two-electron atom. Several dieren t sets of basis functions were systematically explored, starting with the original scheme of Hylleraas. The most rapid convergence is found with a combination of negative powers and a logarithm of the coordinate s = r1 + r2. At N = 3091 terms we pass the previous best calculation (Korobov’s 25 decimal accuracy with N = 5200 terms) and we stop at N = 10257 with E = 2:90372, 43770, 34119, 59831, 11592, 45194, 40444, : : : Previous mathematical analysis sought to link the convergence rate of such calculations to specic analytic properties of the functions involved. The application of that theory to this new experimental data leaves a rather frustrating situation, where we seem able to do little more than invoke vague concepts, such as \exibilit y." We conclude that theoretical understanding here lags well behind the power of available computing machinery.
Spike Timing Precision and Neural Error Correction: Local Behavior

The effects of spike timing precision and dynamical behavior on error correction in spiking neurons were investigated. Stationary discharges—phase locked, quasiperiodic, or chaotic—were induced in a simulated neuron by presenting pacemaker presynaptic spike trains across a model of a prototypical inhibitory synapse. Reduced timing precision was modeled by jittering presynaptic spike times. Aftereffects of errors—in this communication, missed presynaptic spikes—were determined by comparing postsynaptic spike times between simulations identical except for the presence or absence of errors. Results show that the effects of an error vary greatly depending on the ongoing dynamical behavior. In the case of phase lockings, a high degree of presynaptic spike timing precision can provide significantly faster error recovery. For nonlocked behaviors, isolated missed spikes can have little or no discernible aftereffects (or even serve to paradoxically reduce uncertainty in postsynaptic spike timing), regardless of presynaptic imprecision. This suggests two possible categories of error correction: high-precision locking with rapid recovery and low-precision nonlocked with error immunity.
The Disruption of stellar clusters containing massive black holes near the Galactic Center

We present results from dynamical Monte Carlo simulations of dense star clusters near the Galactic center. These clusters sink toward the center of the Galaxy by dynamical friction. During their in-spiral, they may undergo core collapse and form an intermediate-mass black hole through runaway collisions. Such a cluster can then reach within a parsec of the Galactic center before it completely disrupts, releasing many young stars in this region. This scenario provides a natural explanation for the presence of the young stars observed near the Galactic center. Here we determine the initial conditions for this scenario to work, and we derive the mass distribution of cluster stars as a function of distance from the Galactic center. For reasonable initial conditions, we find that clusters massive enough for rapid in-spiral would include a larger number of massive stars (m* 30 M☉) than currently observed in the in-spiral region. We point out several possible explanations for this apparent discrepancy.
Clarifying the Entrepreneurial Orientation Construct and Linking It To Performance

The primary purpose of this article is to clarify the nature of the entrepreneurial orientation (EO) construct and to propose a contingency framework for investigating the relationship between EO and firm performance. We first explore and refine the dimensions of EO and discuss the usefulness of viewing a firm's EO as a multidimensional construct. Then, drawing on examples from the EO-related contingencies literature, we suggest alternative models (moderating effects, mediating effects, independent effects, interaction effects) for testing the EO-performance relationship.
Optical-fiber sensor using tailored porous sol-gel fiber core

A new concept in optical-fiber chemical sensors, the active fiber core optical sensor (AFCOS), is presented. In this sensor, the fiber core acts as a transducer. The sensitivity of an AFCOS sensor is compared with that of an active coating [evanescent wave (EW)] based optical-fiber sensor. Requirements for a fiber core to act as a chemical sensor are discussed. Novel techniques for making a porous sol-gel silica fiber, doping chemical reagents into the fiber, and constructing a chemical sensor using the porous fiber as a transducer have been developed. The microstructure of the fabricated sol-gel silica fiber and the effect of the fiber's microstructure on the capability of the porous sol-gel silica fiber for guiding light are discussed. A humidity sensor employing a CoCl/sub 2/-doped porous sol-gel fiber as a transducer has been constructed as an example. The test results for the humidity sensor verified a theoretical analysis indicating that an optical-fiber chemical sensor using an active fiber core as a transducer has a much higher sensitivity than that of an EW-based sensor.
Assessing the Benefits of Fine- Grain Parallelism in Dataflow Programs

A method for assessing the benefits of fine-grain paral lelism in "real" programs is presented. The method is based on parallelism profiles and speedup curves de rived by executing dataflow graphs on an interpreter under progressively more realistic assumptions about processor resources and communication costs. Even using traditional algorithms, the programs exhibit ample parallelism when parallelism is exposed at all levels. The bias introduced by the language ld and the compiler is examined. A method of estimating speedup through analysis of the ideal parallelism profile is developed, avoiding repeated execution of programs. It is shown that fine-grain parallelism can be used to mask large, unpredictable memory latency and synchronization waits in architectures employing dataflow instruction execu tion mechanisms. Finally, the effects of grouping por tions of dataflow programs, and requiring that the oper ators in a group execute on a single processor, are explored.