cssi/SciSciGPT-SciSciNet huggingface dataset:
Effects of Physician-directed Pharmaceutical Promotion on Prescription Behaviors: Longitudinal Evidence.

Spending on prescription drugs (Rx) represents one of the fastest growing components of US healthcare spending and has coincided with an expansion of pharmaceutical promotional spending. Most (83%) of Rx promotion is directed at physicians in the form of visits by pharmaceutical representatives (known as detailing) and drug samples provided to physicians' offices. Such promotion has come under increased public scrutiny, with critics contending that physician-directed promotion may play a role in raising healthcare costs and may unduly affect physicians' prescribing habits towards more expensive, and possibly less cost-effective, drugs. In this study, we bring longitudinal evidence to bear upon the question of how detailing impacts physicians' prescribing behaviors. Specifically, we examine prescriptions and promotion for a particular drug class based on a nationally representative sample of 150,000 physicians spanning 24 months. The use of longitudinal physician-level data allows us to tackle some of the empirical concerns in the extant literature, virtually all of which have relied on aggregate national data. We estimate fixed-effects specifications that bypass stable unobserved physician-specific heterogeneity and address potential targeting bias. In addition, we also assess differential effects at both the extensive and intensive margins of prescribing behaviors and differential effects across physician-level and market-level characteristics, questions that have not been explored in prior work. The estimates suggest that detailing has a significant and positive effect on the number of new scripts written for the detailed drug, with an elasticity magnitude of 0.06. This effect is substantially smaller than those in the literature based on aggregate information, suggesting that most of the observed relationship between physician-directed promotion and drug sales is driven by selection bias. We find that detailing impacts selective brand-specific demand but does not have any substantial effects on class-level demand. The increase in brand-specific demand appears to crowd out demand for the substitute branded drug although not for the generic alternative. Results also indicate that most of the detailing response may operate at the extensive margin; detailing affects the probability of prescribing the drug more than it affects the number of prescriptions conditional on any prescribing. We draw some implications from these estimates with respect to effects on healthcare costs and public health. Copyright © 2016 John Wiley & Sons, Ltd.
Indian Higher Education

If physical capital — its growth and distribution — was central to debate on economic development in the twentieth century, human capital increasingly occupies centre stage in the twenty-first century (Kapur and Crowley, 2008), and this puts a spotlight on education — whether primary, secondary or tertiary. The very promise of higher education for developing countries is also making this a politically contentious issue. Universities are political because they influence the minds of young adults. And they are becoming even more so because of the growing awareness of the distributional implications of higher education. As private provision and international education grow, issues of equity and access become even more salient. Many of the underlying handicaps faced by students from lower socio-economic groups appear to occur much earlier in the life cycle — at the primary and secondary school levels — but policies to overcome them are pressed only in higher education, often too little and too late. Unsurprisingly the attention devoted to higher education in developing countries has focused mainly on its economic effects, especially its links to labour markets. However, there is little understanding about the way in which its impact is mediated by the type of education and its beneficiaries.
On model-based RIP-1 matrices

The Restricted Isometry Property (RIP) is a fundamental property of a matrix enabling sparse recovery [5]. Informally, an m ×n matrix satisfies RIP of order k in the lp norm if ∥Ax∥p≈∥x∥p for any vector x that is k-sparse, i.e., that has at most k non-zeros. The minimal number of rows m necessary for the property to hold has been extensively investigated, and tight bounds are known. Motivated by signal processing models, a recent work of Baraniuk et al [3] has generalized this notion to the case where the support of x must belong to a given model, i.e., a given family of supports. This more general notion is much less understood, especially for norms other than l2. In this paper we present tight bounds for the model-based RIP property in the l1 norm. Our bounds hold for the two most frequently investigated models: tree-sparsity and block-sparsity. We also show implications of our results to sparse recovery problems.
A Comparison of the Effectiveness of Using Futures, Options, LRP Insurance, or AGR-Lite Insurance to Manage Risk for Cow-calf Producers

A comparative analysis was performed looking at using cash, futures, options, or insurance to manage the price of calves for cow-calf producer. Risk can be reduced with the futures market and with options or LRP insurance. Options and LRP insurance are equivalent in the amount of risk that is reduced. AGR-Lite does not appear to be an effective policy at reducing risk for cow-calf producers.
Distributive Justice in Education and Conflicting Interests: Not (Remotely) as Bad as you Think

The importance of education and its profound effect on people's life make it a central issue in discussions of distributive justice. However, promoting distributive justice in education comes at a price: prioritising the education of some, as is often entailed by the principles of justice, inevitably has negative effects on the education of others. As a result, all theories of distributive justice in education face the challenge of balancing their requirements with conflicting interests. This article aims to contribute to developing an account of conflicting interests by identifying a category of conflicting interests—non-positional conflicting interests—the realisation of which does not necessarily disrupt distributive justice. Non-positional conflicting interests include, for example, the interest in realising one's full potential and parents’ interest in familial relations. The article argues that the core dimensions of non-positional conflicting interests can usually be realised without upsetting distributive justice, and that actions that do upset distributive justice tend to be peripheral to these interests. Either way, there is no severe friction between distributive justice and non-positional conflicting interests: in the former cases, both are realised simultaneously. In the latter, tension exists; however, because the infringement on the conflicting interest is of relatively little weight, it is often justified, all things considered, in order to promote distributive justice. The conclusion is that while there are indeed cases in which distributive justice must retreat in the face of other interests, the friction between distributive justice and other interests is actually weaker than meets the eye.
High-Dimensional Multi-modal Image Registration

This paper presents a Bayesian framework for generating inter-subject high-dimensional transformations between two multi-modal image sets of the brain. In this framework, the estimated transformations are generated by using the maximal information about the underlying neuroanatomy present in each of the different modalities. This modality independent registration framework is achieved by using the Bayesian paradigm and jointly estimating the posterior densities associated with the multi-modal image sets and the high dimensional registration transformation mapping the two subjects. The methods presented do not assume that the same modalities were used to image the two subjects. To maximally use the information present in all the modalities, relative entropy (or Kullback Leibler divergence) between the estimated posteriors is minimized to estimate the registration. The high-dimensional registration is constrained to be diffeomorphic by using the large deformation fluid formulation.
Cosmic rays and particle physics

Preface 1. Cosmic rays 2. Particle physics 3. Cascade equations 4. Hadrons and photons 5. Accelerator data 6. Muons 7. Neutrinos 8. Neutrino-induced muons 9. Propagation 10. Gamma rays and antiprotons 11. Acceleration 12. Acceleration to >100 TeV 13. Astrophysical beam dumps 14. Air showers 15. Electromagnetic cascades 16. Cosmic ray showers 17. Simulation techniques References Index.
Particle Acceleration Very Near an X‐Line in a Collisionless Plasma

In a previous paper, we applied a simplified model for particle motion in the vicinity of a magnetic X-line that had been introduced by Dungey. We used the model to quantitatively show that an electric force along an X-line can be balanced by the gyroviscous force associated with the off-diagonal elements of the pressure tensor. Distribution functions near the X-line were shown to be skewed in azimuth about the magnetic field and to include particles accelerated to very high energies. In the present paper, we apply the previous model and use the distribution functions to evaluate the energization that results from particle interactions with the X-line. We find that, in general, this interaction gives a spectrum of energized particles that can be represented by a Maxwellian distribution. A power-law, high-energy tail does not develop. The thermal energy, K, of the Maxwellian can be expressed simply in terms of the field parameters and particle mass and charge. It is independent of the thermal energy, K(sub i), of the particle distribution incident upon the region of the X-line, provided that K(sub i) is less than K. Significant energization is not found for K(sub i) is greater than K.
Chaos in a semiclassical model of multiphoton excitation of spherical top molecules

We study the dynamical effects of vibration-rotation coupling in multiple photon excitation at lowest order. Our molecular model is the simplest possible: that of an oscillator (triply degenerate) and uncoupled rigid rotor. The molecule-field interactions introduce a vibration-rotation nonlinearity which gives rise to nonconservation of the molecular angular momentum and in some instances consequent chaotic dynamics. The chaos leads to incoherence (widely seen in experiments1) in the time dependence of the photon absorption and is not treatable in an additive way as inhomogeneous broadening.2,4
Is Human Factors Engineering Worth the Investment

The cost of and the savings resulting from three different human factors engineering studies are presented. The data cited indicate clearly that human factors work can be highly cost effective and yield high returns on investment.
Decision-theoretic troubleshooting: a framework for repair and experiment

We develop and extend existing decision-theoretic methods for troubleshooting a nonfunctioning device. Traditionally, diagnosis with Bayesian networks has focused on belief updating--determining the probabilities of various faults given current observations. In this paper, we extend this paradigm to include taking actions. In particular, we consider three classes of actions: (1) we can make observations regarding the behavior of a device and infer likely faults as in traditional diagnosis, (2) we can repair a component and then observe the behavior of the device to infer likely faults, and (3) we can change the configuration of the device, observe its new behavior, and infer the likelihood of faults. Analysis of latter two classes of troubleshooting actions requires incorporating notions of persistence into the belief-network formalism used for probabilistic inference.
The Long Reach of Education: Early Retirement

The goal of this paper is to draw attention to the long lasting effect of education on economic outcomes. We use the relationship between education and two routes to early retirement - the receipt of Social Security Disability Insurance (DI) and the early claiming of Social Security retirement benefits - to illustrate the long-lasting influence of education. We find that for both men and women with less than a high school degree the median DI participation rate is 6.6 times the participation rate for those with a college degree or more. Similarly, men and women with less than a high school education are over 25 percentage points more likely to claim Social Security benefits early than those with a college degree or more. We focus on four critical "pathways" through which education may indirectly influence early retirement - health, employment, earnings, and the accumulation of assets. We find that for women health is the dominant pathway through which education influences DI participation. For men, the health, earnings, and wealth pathways are of roughly equal magnitude. For both men and women the principal channel through which education influences early Social Security claiming decisions is the earnings pathway. We also consider the direct effect of education that does not operate through these pathways. The direct effect of education is much greater for early claiming of Social Security benefits than for DI participation, accounting for 72 percent of the effect of education for men and 67 percent for women. For women the direct effect of education on DI participation is not statistically significant, suggesting that the total effect may be through the four pathways.
Thermofield Duality for Higher Spin Rindler Gravity

We study the Thermo-field realization of the duality between the Rindler-AdS higher spin theory and O(N) vector theory. The CFT represents a decoupled pair of free O(N) vector field theories. It is shown how this decoupled domain CFT is capable of generating the connected Rindler-AdS background with the full set of Higher Spin fields.
Decoherence and Quantum Trajectories

Decoherence is the process by which quantum systems interact and become correlated with their external environments; quantum trajectories are a powerful technique by which decohering systems can be resolved into stochastic evolutions, conditioned on different possible “measurements” of the environment. By calling on recently-developed tools from quantum information theory, we can analyze simplified models of decoherence, explicitly quantifying the flow of information and randomness between the system, the environment, and potential observers.
Calibrated Embeddings in the Special Lagrangian and Coassociative Cases

Every closed, oriented, real analytic Riemannian3–manifold can be isometrically embedded as a specialLagrangian submanifold of a Calabi–Yau 3–fold, even as thereal locus of an antiholomorphic, isometric involution. Every closed,oriented, real analytic Riemannian 4–manifold whose bundle of self-dual2–forms is trivial can be isometrically embedded as a coassociativesubmanifold in a G2-manifold, even as the fixed locus of ananti-G2 involution. These results, when coupledwith McLean's analysis of the moduli spaces of such calibratedsubmanifolds, yield a plentiful supply of examples of compact calibratedsubmanifolds with nontrivial deformation spaces.
Assessing the governance of electricity regulatory agencies in the Latin American and the Caribbean region : a benchmarking analysis

This paper focuses on an evaluation and benchmarking of the governance of regulatory agencies in the electricity sector in Latin American Countries (LAC). Using a unique database, we develop an index of regulatory governance and rank all the agencies in the LAC countries. The index is an aggregate number of the evaluation of four key governance characteristics: autonomy, transparency, accountability, and regulatory tools, including not only formal aspects of regulation but also indicators related to actual implementation. Based on 18 different indexes, we analyze the positions of agencies with regard to different aspects of their regulatory governance, considering not only performance in each variable but also scores in the different components of each category. This evaluation allows for the identification of particular country shortcomings regarding governance, and indicates needed improvements. Although the region shows an overall good governance design of their regulatory agencies, the implementation of the independent regulator model still faces several challenges. This is particularly evident in political autonomy and in the informal aspects of governance, where the region shows the largest number of countries with the lowest scores. Trinidad and Tobago and Brazil show the best results and Ecuador, Honduras, and Chile the poorest performances. The rest of the countries vary according to the different indexes. We give each governance variable equal weights and positively test the robustness of our approach using Principal Component Analysis.
Characterizing Bots' Remote Control Behavior

A botnet is a collection of bots, each generally running on a compromised system and responding to commands over a "command-and-control" overlay network. We investigate observable differences in the behavior of bots and benign programs, focusing on the way that bots respond to data received over the network. Our experimental platform monitors execution of an arbitrary Win32 binary, considering data received over the network to be tainted, applying library-call-level taint propagation, and checking for tainted arguments to selected system calls. As a way of further distinguishing locally-initiated from remotely-initiated actions, we capture and propagate "cleanliness" of local user input (as received via the keyboard or mouse). Testing indicates behavioral separation of major bot families (agobot, DSNXbot, evilbot, G-SySbot, sdbot, Spybot) from benign programs with low error rate.
Tuning the magnetism of ordered and disordered strongly-correlated electron nanoclusters

Recently, there has been a resurgence of intense experimental and theoretical interest on the Kondo physics of nanoscopic and mesoscopic systems due to the possibility of making experiments in extremely small samples. We have carried out exact diagonalization calculations to study the e ect of energy spacing Δ in the conduction band states, hybridization, number of electrons, and disorder on the ground-state and thermal properties of strongly-correlated electron nanoclusters. For the ordered systems, the calculations reveal for the first time that Δ tunes the interplay between the local Kondo and non local RKKY interactions, giving rise to a “Doniach phase diagram” for the nanocluster with regions of prevailing Kondo or RKKY correlations. The interplay of Δ and disorder gives rise to a Δ versus concentration T=0 phase diagram very rich in structure. The parity of the total number of electrons alters the competition between the Kondo and RKKY correlations. The local Kondo temperatures, T K , and RKKY interactions depend strongly on the local environment and are overall enhanced by disorder, in contrast to the hypothesis of “Kondo disorder” single-impurity models. This interplay may be relevant to experimental realizations of small rings or quantum dots with tunable magnetic properties.
Pseudoscalar portal dark matter and new signatures of vector-like fermions

Fermionic dark matter interacting with the Standard Model sector through a pseudoscalar portal could evade the direct detection constraints while preserving a WIMP miracle. Here, we study the LHC constraints on the pseudoscalar production in simplified models with the pseudoscalar either dominantly coupled to b quarks or $${ {\tau}}$$ leptons and explore their implications for the GeV excesses in gamma ray observations. We also investigate models with new vector-like fermions that could realize the simplfied models of pseudoscalar portal dark matter. Furthermore, these models yield new decay channels and signatures of vector-like fermions, for instance, bbb; b$${ {\tau}}$$ $${ {\tau}}$$, and $${ {\tau}}$$ $${ {\tau}}$$ $${ {\tau}}$$ resonances. Some of the signatures have already been strongly constrained by the existing LHC searches and the parameter space fitting the gamma ray excess is further restricted. Conversely, the pure $${ {\tau}}$$-rich final state is only weakly constrained so far due to the small electroweak production rate.
Games with Incomplete Information

Game theory is a theory of strategic interaction. That is to say, it is a theory of rational behavior in social situations in which each player has to choose his moves on the basis of what he thinks the other players’ countermoves are likely to be.
Fibred knots and twisted Alexander invariants

We study the twisted Alexander invariants of fibred knots. We establish necessary conditions on the twisted Alexander invariants for a knot to be fibred, and develop a practical method to compute the twisted Alexander invariants from the homotopy type of a monodromy. It is illustrated that the twisted Alexander invariants carry more information on fibredness than the classical Alexander invariants, even for knots with trivial Alexander polynomials.
Estimating the Cost of Large Superconducting Thin Solenoid Magnets

The cost of thin superconducting solenoid magnets can be estimated if one knows the magnet stored energy, the magnetic field volume product or the overall mass of the superconducting coil and its cryostat. This report shows cost data collected since 1979 for large superconducting solenoid magnets used in high energy physics. These magnets are characterized in most cases by the use of indirect two phase helium cooling and a superconductor stabilizer of very pure aluminum. This correlation can be used for making a preliminary cost estimate of proposed one of a kind superconducting magnets. The magnet costs quoted include the power supply and quench protection system but the cost of the helium refrigerator and helium distribution system is not included in the estimated cost.
Investing in schools: capital spending, facility conditions, and student achievement

Abstract Public investments in repairs, modernization, and construction of schools cost billions. However, little is known about the nature of school facility investments, whether it actually changes the physical condition of public schools, and the subsequent causal impacts on student achievement. We study the achievement effects of nearly 1400 capital campaigns initiated and financed by local school districts, comparing districts where school capital bonds were either narrowly approved or defeated by district voters. Overall, we find little evidence that these school capital campaigns improve student achievement. Event-study analysis focused on the students actually affected by large campus renovations also generates very precise zero estimates of achievement effects. Thus, U.S. school capital campaigns financed by local districts – the predominant method through which facility investments are made – may be a limited tool for realizing substantial gains in student achievement or closing achievement gaps.
Ultra-wideband communications: an idea whose time has come

Summary form only given. Ultra-wideband (UWB) refers to bandwidths in excess of 2 GHz, whose utilization by radar systems dates back to the late '60s. The renewed and rapidly growing interest for UWB was sparked by the spectral mask released by FCC in February 2002, and is well motivated by the attractive features UWB brings to commercial communications: low-power carrier-free transmissions, ample multipath diversity, enhanced penetration capability, low-complexity transceivers, ability to overlay existing systems, and a potential for increase in capacity. This article outlines features and challenges unique to UWB, with emphasis on timely signal processing issues that focus on synchronization, channel estimation, multiple access, and suppression of interference UWB systems cause to (and suffer from) co-existing narrowband systems. Application areas include shortrange indoor wireless links at home, and in the workplace for low-cost multimedia communications and storage, as well as secure connectivity for ranging, and covert communications.
Safe Screening for Multi-Task Feature Learning with Multiple Data Matrices

Multi-task feature learning (MTFL) is a powerful technique in boosting the predictive performance by learning multiple related classification/ regression/clustering tasks simultaneously. However, solving the MTFL problem remains challenging when the feature dimension is extremely large. In this paper, we propose a novel screening rule--that is based on the dual projection onto convex sets (DPC)--to quickly identify the inactive features--that have zero coefficients in the solution vectors across all tasks. One of the appealing features of DPC is that: it is safe in the sense that the detected inactive features are guaranteed to have zero coefficients in the solution vectors across all tasks. Thus, by removing the inactive features from the training phase, we may have substantial savings in the computational cost and memory usage without sacrificing accuracy. To the best of our knowledge, it is the first screening rule that is applicable to sparse models with multiple data matrices. A key challenge in deriving DPC is to solve a nonconvex problem. We show that we can solve for the global optimum efficiently via a properly chosen parametrization of the constraint set. Moreover, DPC has very low computational cost and can be integrated with any existing solvers. We have evaluated the proposed DPC rule on both synthetic and real data sets. The experiments indicate that DPC is very effective in identifying the inactive features--especially for high dimensional data--which leads to a speedup up to several orders of magnitude.
Topology independent protein structural alignment

Protein structural alignment is an indispensable tool used for many different studies in bioinformatics. Most structural alignment algorithms assume that the structural units of two similar proteins will align sequentially. This assumption may not be true for all similar proteins and as a result, proteins with similar structure but with permuted sequence arrangement are often missed. We present a solution to the problem based on an approximation algorithm that finds a sequenceorder independent structural alignment that is close to optimal. We first exhaustively fragment two proteins and calculate a novel similarity score between all possible aligned fragment pairs. We treat each aligned fragment pair as a vertex on a graph. Vertices are connected by an edge if there are intra residue sequence conflicts. We regard the realignment of the fragment pairs as a special case of the maximum-weight independent set problem and solve this computationally intensive problem approximately by iteratively solving relaxations of an appropriate integer programming formulation. The resulting structural alignment is sequence order independent. Our method is insensitive to gaps, insertions/ deletions, and circular permutations.
Logic and database systems

Progress toward true “knowledge-base” systems will be much harder than people imagine, if history is a guide.
Pain self-management in HIV-infected individuals with chronic pain: a qualitative study.

Objective Chronic pain in individuals with HIV is a common, impairing condition. Behavioral interventions for chronic pain specifically tailored to this population have yet to be developed. We assert that understanding self-management strategies already used by persons living with these conditions is an essential first step, and is the objective of this investigation. Design We conducted a thematic analysis of qualitative data from 25 in-depth interviews with individuals with HIV and chronic pain. Results The primary pain self-management strategies articulated by participants were: physical activity; cognitive and spiritual strategies; spending time with family and friends and social support; avoidance of physical/social activity; medication-centric pain management; and substance use. Conclusions Some of these strategies may be viewed as beneficial and overlap with known HIV self-management strategies (cognitive strategies), whereas others may have negative health consequences (substance use). Interventions that incorporate healthy self-management strategies may be particularly effective in improving both HIV and pain outcomes.
Rater Agreement – Weighted Kappa

One of the characteristics of Cohen's kappa (κ) is that any discrepancy between raters is equally weighted as zero. On the other hand, any agreement means absolute agreement between raters, and is equally weighted as one. Thus, the distinction between agreement and disagreement is categorical. For example, Table 1 from the Cohen's kappa section shows three agreement cells and six disagreement cells. In deriving Cohen's kappa, all six disagreement cells are treated equally. However, there could be situations in which the discrepancy between adjacent categories such as Categories 1 and 2 can be considered as partial agreement as opposed to complete disagreement. In those situations, Cohen's weighted kappa can be used to reflect the magnitude of agreement. Keywords: kappa; weighted kappa; agreement
Some curvature pinching results for Riemannian manifolds with density

In this note we consider versions of both Ricci and sectional curvature pinching for Riemannian manifold with density. In the Ricci curvature case the main result implies a diameter estimate that is new even for compact shrinking Ricci solitons. In the case of sectional curvature we prove a new sphere theorem.
Crab nebula gamma-ray flares as relativistic reconnection minijets

The unusually short durations, high luminosities and high photon energies of the Crab nebula gamma-ray flares require the relativistic bulk motion of the emitting plasma. We explain the Crab flares as a result of randomly oriented relativistic ‘minijets’ originating from reconnection events in a magnetically dominated plasma. We develop a statistical model of the emission from Doppler boosted reconnection minijets and find analytical expressions for the moments of the resulting nebula light curve (e.g. time average, variance, skewness). The light curve has a flat power spectrum that transitions at short time-scales to a decreasing power law of index 2. The flux distribution from minijets follows a decreasing power law of index ∼1, implying that the average flux from flares is dominated by bright rare events. The predictions for the flares’ statistics can be tested against forthcoming observations. We find that the observed flare spectral energy distributions (SEDs) have several notable features: a hard power-law index of p ≲ 1 for accelerated particles that is expected in various reconnection models, including some evidence of a pile-up near the radiation reaction limit. Also, the photon energy at which the SED peaks is higher than that implied by the synchrotron radiation reaction limit, indicating that the flare emission regions’ Doppler factors are ≳ a few. We conclude that magnetic reconnection can be an important, if not dominant, mechanism of particle acceleration within the nebula.
Callisto: New Insights from Galileo Disk-resolved UV Measurements

The entire set of observations from the Galileo Ultraviolet Spectrometer (UVS) is analyzed to look for spectral trends across the surface of Callisto, and to probe the spectral shapes in the near-UV. At low resolution, the leading hemisphere is slightly redder than the trailing hemisphere at -->λ > 280 nm; this has been interpreted by past researchers to indicate the presence of SO2 on the leading hemisphere. Here we point out that such an absorption feature can be induced when ratioing hemispherical spectra. High-resolution observations are used to detect the presence of an absorption band at high southern latitudes, interpreted to be due to some organic species that is weathered away (carbonized) at lower latitudes. The presence of CO2 in the surface and in the atmosphere of Callisto and the dark nature of the surface suggest that carbon-based species are present across the surface associated with either endogenic or delivered organics. These organics experience chemical modification by UV radiation and are mixed into the regolith by meteoritic bombardment.
Spatial-frequency composite watermarking for digital image copyright protection

Digital watermarks can be classified into two categories according to the embedding and retrieval domain, i.e. spatial- and frequency-domain watermarks. Because the two watermarks have different characteristics and limitations, combination of them can have various interesting properties when applied to different applications. In this research, we examine two spatial-frequency composite watermarking schemes. In both cases, a frequency-domain watermarking technique is applied as a baseline structure in the system. The embedded frequency- domain watermark is robust against filtering and compression. A spatial-domain watermarking scheme is then built to compensate some deficiency of the frequency-domain scheme. The first composite scheme is to embed a robust watermark in images to convey copyright or author information. The frequency-domain watermark contains owner's identification number while the spatial-domain watermark is embedded for image registration to resist cropping attack. The second composite scheme is to embed fragile watermark for image authentication. The spatial-domain watermark helps in locating the tampered part of the image while the frequency-domain watermark indicates the source of the image and prevents double watermarking attack. Experimental results show that the two watermarks do not interfere with each other and different functionalities can be achieved. Watermarks in both domains are detected without resorting to the original image. Furthermore, the resulting watermarked image can still preserve high fidelity without serious visual degradation.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
On modeling multi-component diffusion inside the porous anode of solid oxide fuel cells using Fick's model

Abstract Stefan–Maxwell model (SMM) and simple Fick's model (FM) type of relations both including Knudsen diffusion for the calculation of species mole fraction distribution inside the porous anode of a solid oxide fuel cell (SOFC) were compared and it was found that at low current densities the models agree well but as current increases the differences also increase. Based on the findings an empirical correction is proposed for the effective diffusivity used in Fick's model. The corrected diffusivity coefficient gave better agreement with the Stefan–Maxwell model and even at higher current densities the error is less than 5%. This correction was implemented via a three-dimensional, in-house SOFC simulation code (DREAMSOFC) which uses Fick's model type relations for diffusion flux calculations. The code also takes into account methane steam reforming (MSR) and water gas shift (WGS) reactions and the electrochemical oxidation of both H 2 and CO. As an application, a SOFC button cell which is being tested at West Virginia University was simulated. The results with and without the proposed correction for effective diffusivity are compared.
The first stereoselective Ficini-Claisen rearrangement using chiral ynamides.

The first asymmetric Ficini−Claisen rearrangement using chiral ynamides is described. At relatively low temperatures, the Ficini−Claisen rearrangement can be efficiently promoted by p-nitrobenzenesulfonic acid leading to high diastereoselectivity for a range of different allylic alcohols and chiral ynamides.
Regional Consistency: Programmability and Performance for Non-cache-coherent Systems

Parallel programmers face the often irreconcilable goals of programmability and performance. HPC systems use distributed memory for scalability, thereby sacrificing the programmability advantages of shared memory programming models. Furthermore, the rapid adoption of heterogeneous architectures, often with non-cache-coherent memory systems, has further increased the challenge of supporting shared memory programming models. Our primary objective is to define a memory consistency model that presents the familiar thread-based shared memory programming model, but allows good application performance on non-cache-coherent systems, including distributed memory clusters and accelerator-based systems. We propose regional consistency (RegC), a new consistency model that achieves this objective. Results on up to 256 processors for representative benchmarks demonstrate the potential of Reg C in the context of our prototype distributed shared memory system.
Total synthesis of taxol

Taxol, a substance originally isolated from the Pacific yew tree (Taxus brevifolia) more than two decades ago, has recently been approved for the clinical treatment of cancer patients. Hailed as having provided one of the most significant advances in cancer therapy, this molecule exerts its anticancer activity by inhibiting mitosis through enhancement of the polymerization of tubulin and consequent stabilization of microtubules. The scarcity of taxol and the ecological impact of harvesting it have prompted extension searches for alternative sources including semisynthesis, cellular culture production and chemical synthesis. The latter has been attempted for almost two decades, but these attempts have been thwarted by the magnitude of the synthetic challenge. Here we report the total synthesis of taxol by a convergent strategy, which opens a chemical pathway for the production of both the natural product itself and a variety of designed taxoids.
Advances in Numerical Boundary Conditions for Computational Aeroacoustics

Advances in Computational Aeroacoustics (CAA) depend critically on the availability of accurate, nondispersive, least dissipative computation algorithm as well as high quality numerical boundary treatments. This paper focuses on the recent developments of numerical boundary conditions. In a typical CAA problem, one often encounters two types of boundaries. Because a finite computation domain is used, there are external boundaries. On the external boundaries, boundary conditions simulating the solution outside the computation domain are to be imposed. Inside the computation domain, there may be internal boundaries. On these internal boundaries, boundary conditions simulating the presence of an object or surface with specific acoustic characteristics are to be applied. Numerical boundary conditions, both external or internal, developed for simple model problems are reviewed and examined. Numerical boundary conditions for real aeroacoustic problems are also discussed through specific examples. The paper concludes with a description of some much needed research in numerical boundary conditions for CAA.
Coupled multiline CW HF lasers - Experimental performance

The experimental performance of two coupled arc-driven continuous wave HF chemical lasers employing unstable resonators has been measured. Mode-matched adjoint coupling of 20% was accomplished with a beamsplitter. Multiline interference fringes were obtained when the two laser output beams were overlapped in the near field. The mutual coherence of the two beams was inferred from measurement of the visibility of these fringes. Single-tine fringe visibility was measured as 98% +/—2% for each of the two strongest lines. These data suggest that the two outputs are nearly completely phase locked. This locking was found to be insensitive to perturbations in the lengths of the laser resonators. Mode-beating measurements also suggest complete phase locking, since the coupled system behaves tike a single laser cavity. The coherent combination of the two laser output beams was attempted by minimizing the optical path difference between these beams at an external measuring station. This was achieved by changing the external path length of one beam until maximum multiline visibility (97%) was obtained. Demonstration of the corresponding far-field peak intensity enhancement and reduction in spot size for the combined outputs was also accomplished.
Surface markers for the murine oval cell response.

The biology of progenitor activation in the liver is of considerable medical and scientific interest. The powerful genetic tools available for the mouse make it an ideal model system to study this complex process involving many different cell types. However, reagents for the isolation and study of distinct hepatic subpopulations have been quite limited compared to those available for hematopoietic cells. To produce cell surface reactive reagents more specific for the oval cell response, we generated a new collection of monoclonal antibodies by immunization of Fischer rats with enzymatically dispersed nonparenchymal cells from the livers of adult mice treated with 3,5-diethoxycarbonyl-1,4-dihydrocollidine. Each of the resulting antibodies recognized a surface antigen present on a liver cell subset and permitted the viable isolation of the associated subpopulation by fluorescence-activated cell sorting. Differential activity was observed on normal liver cells and at different stages of oval cell activation, indicating potential utility for progenitor cell identification. The subdivision of liver cells using these tools should facilitate the study of the biology of ductal and periductal hepatic cell types, including progenitors. Conclusion: A new panel of surface reactive monoclonal antibodies to support investigation of the murine oval cell response has been developed. (HEPATOLOGY 2008.)
Spin correlations in the algebraic spin liquid: Implications for high-T c superconductors

We propose that underdoped high-${T}_{c}$ superconductors are described by an algebraic spin liquid (ASL) at high energies, which undergoes a spin-charge recombination transition at low energies. The spin correlation in the ASL is calculated via its effective theory---a system of massless Dirac fermions coupled to a U(1) gauge field. We find that without fine-tuning any parameters the gauge interaction strongly enhances the staggered spin correlation even in the presence of a large single-particle pseudogap. This allows us to show that the ASL plus spin-charge recombination picture can explain many highly unusual properties of underdoped high-${T}_{c}$ superconductors.
Vapor-wall deposition in chambers: theoretical considerations.

In order to constrain the effects of vapor–wall deposition on measured secondary organic aerosol (SOA) yields in laboratory chambers, researchers recently varied the seed aerosol surface area in toluene oxidation and observed a clear increase in the SOA yield with increasing seed surface area (Zhang, X.; et al. Proc. Natl. Acad. Sci. U.S.A. 2014, 111, 5802). Using a coupled vapor–particle dynamics model, we examine the extent to which this increase is the result of vapor–wall deposition versus kinetic limitations arising from imperfect accommodation of organic species into the particle phase. We show that a seed surface area dependence of the SOA yield is present only when condensation of vapors onto particles is kinetically limited. The existence of kinetic limitation can be predicted by comparing the characteristic time scales of gas-phase reaction, vapor–wall deposition, and gas–particle equilibration. The gas–particle equilibration time scale depends on the gas–particle accommodation coefficient αp. R...
Geomagnetic field mapping from a satellite: Spatial power spectra of the geomagnetic field at various satellite altitudes relative to natural noise sources and instrument noise

For a low-level geomagnetic satellite survey, for which the motion of the satellite converts spatial variation into temporal variation, the limit on accuracy may well be background temporal fluctuations. The sources of the temporal fluctuations are current systems external to the Earth and include currents induced in the Earth due to these sources. The internal sources consist primarily of two components, the main geomagnetic field with sources in the Earth's core and a crustal geomagnetic field. Power spectra of the vertical geomagnetic field internal component that would be observed by a spacecraft in circular orbit at various altitudes, due to satellite motion through the spatially varying geomagnetic field, are compared to power spectra of the natural temporal fluctuations of the geomagnetic field vertical component (natural noise) and to the power spectrum for typical fluxgate magnetometer instrument noise. The natural noise is shown to be greater than this typical instrument noise over the entire frequency range for which useful measurements of the geomagnetic field may be made, for all geomagnetic latitudes and all times. Thus there would be little benefit in reducing the instrument noise below the typical value of 10−4 gamma2 Hz−1 plus a 1/f component of 10 milligamma rms decade−1. For a given satellite altitude, there is a maximum frequency above which the natural noise is greater than the power spectrum of the crustal geomagnetic field vertical component. Below this maximum frequency, the situation is reversed. This maximum frequency depends on geomagnetic latitude (and to a lesser extent on time of day and season of year), being lower in the auroral zone than at lower latitudes. The maximum frequency is also lower at higher satellite altitudes. The maximum frequency determines the spatial resolution obtainable on a magnetic field map. The spatial resolution (for impulses) obtainable at low latitudes for a 100-km satellite altitude (possibly achievable by tethering a small satellite at this altitude to a space vehicle at a higher altitude) is 60 km, while at the auroral zone the obtainable spatial resolution is 100 km. At the higher satellite altitude of 300 km the obtainable spatial resolution is 230 km at low latitudes and 530 km at the auroral zone. At 500-km satellite altitude, the obtainable spatial resolution is 500 km at low latitudes, while maps cannot be made at all for the auroral zone unless the data are selected for “quiet” days. For the lower satellite altitudes, greater spatial resolution can be obtained than at higher altitudes. Furthermore since the crustal geomagnetic field power spectrum is larger at lower altitudes, the relative error due to the natural noise is less than for higher altitudes.
On the factors that affect airline flight frequency and aircraft size

This paper assesses the determinants of aircraft size and frequency of flights on US airline routes by considering market demographics, airport characteristics, airline characteristics and route characteristics. It shows that frequency and aircraft size increase with population, income, and runway length. An increase in the proportion of managerial workers in the labor force or the proportion of population below the age of 25 results in greater frequency with the use of small planes. Slot constrained airports and an increase in the number of nearby airports lead to lower flight frequency with the use of smaller planes. Hubs and low cost carriers are associated with larger plane sizes and higher frequency, while regional airline ownership leads to higher frequency and the use of smaller planes. An increase in distance between the endpoints leads to lower frequency with the use of larger planes. As airport delay rises, airlines reduce frequency and use smaller planes, though when airport cancellations rise, flight frequency increases with the use of larger planes.
The Institutional Environment for Economic Growth

This article forges an explicit link between an objective measure of political constraints and variation in cross-national growth rates. It derives a new measure of political constraints from a simple spatial model of political interaction that incorporates information on the number of independent branches of government with veto power and the distribution of preferences across and within those branches. The derived variable is found to have a statistically and economically significant impact on growth rates using simple ordinary least squares, three-stage least squares and generalized method of moments estimation techniques.