cssi/SciSciGPT-SciSciNet huggingface dataset:
Definition and complexity of some basic metareasoning problems

In most real-world settings, due to limited time or other resources, an agent cannot perform all potentially useful deliberation and information gathering actions. This leads to the metareasoning problem of selecting such actions. Decision-theoretic methods for metareasoning have been studied in AI, but there are few theoretical results on the complexity of metareasoning. We derive hardness results for three settings which most real metareasoning systems would have to encompass as special cases. In the first, the agent has to decide how to allocate its deliberation time across anytime algorithms running on different problem instances. We show this to be ATP-complete. In the second, the agent has to (dynamically) allocate its deliberation or information gathering resources across multiple actions that it has to choose among. We show this to be AfP-hard even when evaluating each individual action is extremely simple. In the third, the agent has to (dynamically) choose a limited number of deliberation or information gathering actions to disambiguate the state of the world. We show that this is AfP-hard under a natural restriction, and PSP ACE hard in general.
Nonuniversal soft supersymmetry breaking and dark matter

An analysis is given of the effects of nonuniversal soft supersymmetry-breaking masses in the Higgs sector and in the third generation squark sector, and it is shown that they are highly coupled. Nonuniversality effects on dark matter event rates in neutralino-nucleus scattering are analyzed. It is found that the effects are maximal in the range m{sub {tilde {chi}}{sub 1}}{le}65 GeV where the relic density is governed by the Z and Higgs poles. In this range the minimum event rates can be increased or decreased by factors of {approximately}10 depending on the sign of nonuniversality. Above this range Landau pole effects arising from the heavy top quark mass tend to suppress the nonuniversality effects. The effect of more precise measurements of cosmological parameters on event rates, which is expected to occur in the next round of COBE-like satellite experiments, is also investigated. Implications for the analysis for dark matter searches are discussed. {copyright} {ital 1997} {ital The American Physical Society}
Optical/X-Ray Framing Camera Tube

A new type of framing camera tube for either x-ray or optical events is being developed at LLL that should have capabilities of sub-100 psec framing times. The concept of such a camera is based on dissection of an electron-image through a multiple aperture plate in an image converter tube. Each aperture in the plate produces an image frame. By use of synchronized deflection in both the dissector and restorer sections of the tube, the sequentially time-developed images from an aperture are restored to an electron-image frame at the phosphor screen.
Effect of Slip on Circulation Inside a Droplet

Internal recirculation in a moving droplet plays an important role in several droplet-based microfluidic devices as it enhances mixing, chemical reaction and heat transfer. The occurrence of fluid slip at the wall, which becomes prominent at high shear rates and lower length scales, results in a significant change in droplet circulation. Using molecular dynamics (MD) simulations, the presence of circulation in droplets is demonstrated and quantified. Circulation is shown to vary inversely with slip length, which is a measure of interface wettability. A simple circulation model is established that captures the effect of slip on droplet circulation. Scaling parameters for circulation and slip length are identified from the circulation model which leads to the collapse of data for droplets with varying aspect ratio (AR) and slip length. The model is validated using continuum and MD simulations and is shown to be accurate for droplets with high AR.
Non-relativistic matter and quantized radiation

This is a didactic review of spectral and dynamical properties of atoms and molecules at energies below the ionization threshold, the focus being on recent work in which the author was involved. As far as possible, the results are described using a simple model with one electron only, and with scalar bosons. The main ideas are explained but no complete proofs are given. The full-fledged standard model of non-relativistic QED and various of its aspects are described in the appendix. ∗Supported in part by U.S. National Science Foundation grant DMS 01-00160. M. Griesemer: Non-Relativistic Matter and Quantized Radiation, Lect. Notes Phys. 695, 217–248 (2006) www.springerlink.com
Causal discovery from a mixture of experimental and observational data

This paper describes a Bayesian method for combining an arbitrary mixture of observational and experimental data in order to learn causal Bayesian networks. Observational data are passively observed. Experimental data, such as that produced by randomized controlled trials, result from the exoerimenter manioulatine one or more variables (tipically randomiy) and observing the states of other variables. The paper presents a Bayesian method for learning the causal structure and parameters of the underlying causal process that is generating the data, given that (1) the data contains a mixture of observational and experimental case records, and (2) the causal process is modeled as a causal Bayesian network. This learning method was applied using as input various mixtures of experimental and observational data that were generated from the ALARM causal Bayesian network. In these experiments, the absolute and relative quantities of experimental and observational data were varied systematically. For each of these training datasets, the learning method was applied to predict the causal structure and to estimate the causal parameters that exist among randomly selected pairs of nodes in ALARM that are not confounded. The paper reports how these structure predictions and parameter estimates compare with the true causal structures and parameters as given by the ALARM network.
Infrared surface temperature measurements in NAVSWC's hypervelocity wind tunnel No.9

The authors describe efforts at the US Naval Surface Warfare Center's Hypervelocity Wind Tunnel No.9 to measure wind tunnel model surface temperatures using a commercially available infrared (IR) camera. IR camera measurements on a Macor model surface tested at Mach 14 in Tunnel 9 are presented, and the data are compared to vapor-deposited thermocouple measurements made on the same substrate. The IR data were collected using an Inframetrics Model 600 infrared camera and were reduced using the camera manufacturer's software. The results of this analysis show the feasibility of making global nonintrusive heat transfer measurements using an infrared camera. >
Compressed silica aerogels for the study of superfluid 3He

We have performed Small Angle X‐ray Scattering (SAXS) on uniaxially strained aerogels and measured the strain‐induced structural anisotropy. We use a model to connect our SAXS results to anisotropy of the 3He quasiparticle mean free path in aerogel.
A Mysterious Duality: M-Theory And Del Pezzo Surfaces

The discovery of duality symmetries in string theory has led to spectacular progress in our understanding of non-perturbative aspects of the theory. However, we still do not have a deep understanding of the meaning of these symmetries. Indeed, we find ourselves in the strange situation that the quantum corrected physics has more symmetries than the classical strings had any right to expect! It would be desirable to have a formulation of M-theory in which the U-duality symmetries were manifest. Here we will briefly describe a curious correspondence which may provide a hint about the ingredients of such a formulation.
Coherent lattice QCD

We discuss a proposal for the construction of lattice QCD with gauge action, fermionic action, θ–term, and the operators all based on the lattice Dirac operator D with exact chiral symmetry. The simplest regularization of this type uses the proposition that the classical limit of scalar gauge density associated with trace of D is (up to an additive constant) proportional to trF2, while the corresponding operator is local. More general formulations from this class are considered with the aim of exposing interrelations between gauge and fermionic aspects of QCD which are otherwise hidden in generic formulations. Possible utility of these formulations for exploring QCD vacuum structure is emphasized.
Should We Go One Step Further? An Accurate Comparison of One-step and Two-step Procedures in a Generalized Method of Moments Framework

Abstract According to conventional asymptotic theory, the two-step generalized method of moments (GMM) estimator and test perform at least as well as the one-step estimator and test in large samples. The conventional asymptotic theory completely ignores the estimation uncertainty in the weighting matrix, and as a result it may not reflect finite-sample situations well. In this paper, we employ the more accurate fixed-smoothing asymptotic framework to compare the performances of the one-step and two-step procedures. We show that the two-step procedures outperform the one-step procedures only when the squared long-run canonical correlation coefficients between two blocks of transformed moment conditions are larger than the thresholds established in this paper. The thresholds depend on the criteria of interest. A Monte Carlo study lends support to our asymptotic results.
Present views on electrodynamics of moving media.

The recent formulations on electrodynamics of moving media proposed by some authors are reviewed. It is pointed out that all these apparently new formulations can be uncovered in the earlier work of Minkowski and Born. It is recommended that this classical work should be thoroughly covered in the curriculum of educational institutions offering graduate courses in electromagnetic field theory.
A Large Animal Survival Model to Evaluate Bariatric Surgery Mechanisms

Background: The impact of Roux-en-Y gastric bypass (RYGB) on type 2 diabetes mellitus is thought to result from upper and/or lower gut hormone alterations. Evidence supporting these mechanisms is incomplete, in part because of limitations in relevant bariatric-surgery animal models, specifically the lack of naturally insulin-resistant large animals. With overfeeding, Ossabaw swine develop a robust metabolic syndrome, and may be suitable for studying post-surgical physiology. Whether bariatric surgery is feasible in these animals with acceptable survival is unknown. Methods: Thirty-two Ossabaws were fed a high-fat, high-cholesterol diet to induce obesity and insulin resistance. These animals were assigned to RYGB (n = 8), RYGB with vagotomy (RYGB-V, n = 5), gastrojejunostomy (GJ, n = 10), GJ with duodenal exclusion (GJD, n = 7), or sham operation (n = 2) and were euthanized 60 days post-operatively. Post-operative changes in weight and food intake are reported. Results: Survival to scheduled necropsy among surgical groups was 77%, living an average of 57 days post-operatively. Cardiac arrest under anesthesia occurred in 4 pigs. Greatest weight loss (18.0% ± 6%) and food intake decrease (57.0% ± 20%) occurred following RYGB while animals undergoing RYGB-V showed only 6.6% ± 3% weight loss despite 50.8% ± 25% food intake decrease. GJ (12.7% ± 4%) and GJD (1.2% ± 1%) pigs gained weight, but less than sham controls (13.4% ± 10%). Conclusions: A survival model of metabolic surgical procedures is feasible, leads to significant weight loss, and provides the opportunity to evaluate new interventions and subtle variations in surgical technique (e.g. vagus nerve sparing) that may provide new mechanistic insights.
X-Ray Nova XTE J1550–564: RXTE Spectral Observations

Excellent coverage of the 1998 outburst of the X-ray nova XTE J1550-564 was provided by the Rossi X-Ray Timing Explorer (RXTE). XTE J1550-564 exhibited an intense (6.8 crab) flare on 1998 September 19 (UT), making it the brightest new X-ray source observed with RXTE. We present a spectral analysis utilizing 60 Proportional Counter Array spectra from 2.5-20 keV spanning 71 days and a nearly continuous All Sky Monitor light curve. The spectra were fitted to a model including multicolor blackbody disk and power-law components. XTE J1550-564 is observed in the very high, high/soft, and intermediate canonical outburst states of black hole X-ray novae.
A Clinician's tool for analyzing non-compliance

We describe a computer program to assist a clinician with assessing the efficacy of treatments in experimental studies for which treatment assignment is random but subject compliance is imperfect. The major difficulty in such studies is that treatment efficacy is not "identifiable", that is, it cannot be estimated from the data, even when the number of subjects is infinite, unless additional knowledge is provided. Our system combines Bayesian learning with Gibbs sampling using two inputs: (1) the investigator's prior probabilities of the relative sizes of subpopulations and (2) the observed data from the experiment. The system outputs a histogram depicting the posterior distribution of the average treatment effect, that is, the probability that the average outcome (e.g., survival) would attain a given level, had the treatment been taken uniformly by the entire population. This paper describes the theoretical basis for the proposed approach and presents experimental results on both simulated and real data, showing agreement with the theoretical asymptotic bounds.
Bottom-Up ILP Using Large Refinement Steps

The LogAn-H system is a bottom up ILP system for learning multi-clause and multi-predicate function free Horn expressions in the framework of learning from interpretations. The paper introduces a new implementation of the same base algorithm which gives several orders of magnitude speedup as well as extending the capabilities of the system. New tools include several fast engines for subsumption tests, handling real valued features, and pruning. We also discuss using data from the standard ILP setting in our framework, which in some cases allows for further speedup. The efficacy of the system is demonstrated on several ILP datasets.
The end of the rainbow: what can we say about the extragalactic sub-megahertz radio sky?

The Galactic disc is opaque to radio waves from extragalactic sources with frequencies ν less than ∼3 MHz. However, radio waves with kHz, Hz and even lower frequencies may propagate through the intergalactic medium (IGM). I argue that the presence of these waves can be inferred by using the Universe as our detector. I discuss possible sub-MHz sources and set new non-trivial upper limits on the energy density of sub-MHz radio waves in galaxy clusters and the average cosmic background. Limits based on five effects are considered: (1) changes in the expansion of the Universe from the radiation energy density, (2) heating of the IGM by free-free absorption, (3) radiation pressure squeezing of IGM clouds by external radio waves, (4) synchrotron heating of electrons in clusters and (5) inverse Compton upscattering of sub-MHz radio photons. Any sub-MHz background must have an energy density much smaller than the cosmic microwave background at frequencies below 1 MHz. The free-free absorption bounds from the Lyman α (Lyα) forest are potentially the strongest, but are highly dependent on the properties of sub-MHz radio scattering in the IGM. I estimate an upper limit of 6 x 10 4 L ⊙ Mpc -3 for the emissivity within Lyα forest clouds in the frequency range of 5-200 Hz. The sub-MHz energy density in the Coma cluster is constrained to be less than ∼ 10 -15 erg cm -3 . At present, none of the limits is strong enough to rule out a maximal T b = 10 12 K sub-MHz synchrotron background, but other sources may be constrained with better knowledge of sub-MHz radio propagation in the IGM.
Quantization of Eigen Subspace for Sparse Representation

We propose sparse Karhunen–Loeve Transform (SKLT) method to sparse eigen subspaces. The sparsity (cardinality reduction) is achieved through the pdf-optimized quantization of basis function (vector) set. It may be considered an extension of the simple and soft thresholding (ST) methods. The merit of the proposed framework for sparse representation is presented for auto-regressive order one, AR(1), discrete process and empirical correlation matrix of stock returns for NASDAQ-100 index. It is shown that SKLT is efficient to implement and outperforms several sparsity algorithms reported in the literature.
The Melbourne Shuffle: Improving Oblivious Storage in the Cloud

We present a simple, efficient, and secure data-oblivious randomized shuffle algorithm. This is the first secure data-oblivious shuffle that is not based on sorting. Our method can be used to improve previous oblivious storage solutions for network-based outsourcing of data.
Achieving decision consistency across the SOA-Based enterprise using business rules management systems

The adoption of a service-oriented architecture (SOA) provides businesses with the ability to rapidly deploy new applications and easily integrate with other component applications both inside and outside the organization. This decentralized application environment provides a great deal of flexibility for business units and IT departments, but it also creates difficulty in managing the consistency of business decisions delivered through various applications. Business rules management systems (BRMS) provide a mechanism for managing decision logic and act as a conductor in order to align application decision behavior. The key to BRMS is the use of a centralized rules repository, within which resides the decision logic applications use to interact with their customers. Applications communicate with a rules engine in order to process those business rules specific to the decision required for the particular application and situational context. This paper will show how business rules management systems fit within a service-oriented architecture, how BRMS can act as intermediary between service-based applications and legacy applications, and how companies are using BRMS to manage decision processes across the enterprise.
Capital Flows, Country Risk, and Contagion

It has been widely recognized that both country-specific and global factors matter in explaining capital flows. Fiess presents an empirical framework that disentangles the relative weight of country-specific and global factors in determining capital flows. In essence, his approach first separates the common component of emerging country spreads from their country-specific component. The pure country risk and global risk components are then used as explanatory variables to account for the observed pattern of capital flows using multivariate cointegration analyses. The author is able to identify the relative weight of global and country-specific factors in explaining capital flows to Argentina, Brazil, Mexico, and Venezuela in the 1990s. When further decomposing country risk into its determinants, the author finds that within a small system it is possible to jointly identify the determinants of capital flows and sovereign bond spreads. We find that capital flows are driven by country risk and global factors ("contagion" and U.S. long-term interest rates), while country risk is determined by the primary balance-to-GDP ratio (-) and the ratio of public debt to GDP (+). This paper - a product of the Office of the Chief Economist, Latin America and the Caribbean Region - is part of a larger effort in the region to understand international capital flows.
Evaluating MJO event initiation and decay in the skeleton model using an RMM-like index

The Madden-Julian oscillation (MJO) skeleton model is a low-order dynamic model that is capable of simulating many of the observed features of the MJO. This study develops a model-based “MJO” index that is similar to the well-known real-time multivariate MJO (RMM) index to better facilitate comparison between the skeleton model and observational data. Multivariate and univariate empirical orthogonal function (EOF) analyses were performed on the convective heating and zonal wind data taken from the skeleton model for simulations forced with an idealized warm pool and observed sea surface temperatures (SSTs). The leading EOF modes indicated a wave number 1 convectively coupled circulation anomaly with zonal asymmetries that closely resembled the observed RMM EOFs, especially when the model was forced with observed SSTs. The RMM-like index was used to compute an MJO climatology and document the occurrence of primary, continuing, and terminating MJO events in the skeleton model. The overall amount of MJO activity and event lengths compared reasonably well to observations for such a simple model. Attempts at reconciling the observed geographic distribution of individual MJO initiation and termination events were not successful for the stochastic simulations, though stochasticity is necessary in order to produce composite MJOs that initiate and decay with time scales similar to observations. Finally, analysis indicates that the existence of slow-moving, eastward traveling waves with higher wave numbers (k ≈ 12) embedded within the large-scale flow often precedes MJO termination in the skeleton model.
Improving Computer-Aided Detection Using Convolutional Neural Networks and Random View Aggregation

Automated computer-aided detection (CADe) has been an important tool in clinical practice and research. State-of-the-art methods often show high sensitivities at the cost of high false-positives (FP) per patient rates. We design a two-tiered coarse-to-fine cascade framework that first operates a candidate generation system at sensitivities $\sim 100\%$ of but at high FP levels. By leveraging existing CADe systems, coordinates of regions or volumes of interest (ROI or VOI) are generated and function as input for a second tier, which is our focus in this study. In this second stage, we generate 2D (two-dimensional) or 2.5D views via sampling through scale transformations, random translations and rotations. These random views are used to train deep convolutional neural network (ConvNet) classifiers. In testing, the ConvNets assign class (e.g., lesion, pathology) probabilities for a new set of random views that are then averaged to compute a final per-candidate classification probability. This second tier behaves as a highly selective process to reject difficult false positives while preserving high sensitivities. The methods are evaluated on three data sets: 59 patients for sclerotic metastasis detection, 176 patients for lymph node detection, and 1,186 patients for colonic polyp detection. Experimental results show the ability of ConvNets to generalize well to different medical imaging CADe applications and scale elegantly to various data sets. Our proposed methods improve performance markedly in all cases. Sensitivities improved from 57% to 70%, 43% to 77%, and 58% to 75% at 3 FPs per patient for sclerotic metastases, lymph nodes and colonic polyps, respectively.
Switching from Patents to an Intertemporal Bounty in a Non-Scale Growth Model: Transitional Dynamics and Welfare Evaluation

The prize system for innovation has been criticized as impractical due to the lack of a workable formula or algorithm to determine the size of prizes. In this paper, a decentralized market mechanism via the intertemporal bounty (IB) system can function to duplicate Pareto optimality. Under this system, any bountiable innovation is placed in the public domain, and the prize of innovation is dynamically amortized in an infinitely time domain as periodic bounties paid to holders of bounty claims. Periodic bounties are calculated using a government-determined bounty rate times observed market sales. Two formulas are derived to calculate “long-run Pareto optimal bounty rate” and “long-run suboptimal bounty rate.” The former can correct monopoly distortions and externalities, while the latter can only address monopoly distortions. They are empirically computable and can serve as an upper bound and the lower bound of the bounty rate. This paper provides a dynamic general-equilibrium analysis of replacing finitely-lived patents with the IB system using either of these two bounty rates. Based on a non-scale growth model calibrated to the US economy, transition paths are worked out to compute welfare gains.
Negative entropy in quantum information theory

We present a quantum information theory that allows for the consistent description of quantum entanglement. It parallels classical (Shannon) information theory but is based entirely on density matrices, rather than probability distributions, for the description of quantum ensembles. We find that, unlike in Shannon theory, conditional entropies can be negative when considering quantum entangled systems such as an Einstein-Podolsky-Rosen pair, which leads to a violation of well-known bounds of classical information theory. Negative quantum entropy can be traced back to “conditional” density matrices which admit eigenvalues larger than unity. A straightforward definition of mutual quantum entropy, or “mutual entanglement,” can also be constructed using a “mutual” density matrix. Such a unified information-theoretic description of classical correlation and quantum entanglement clarifies the link between them: the latter can be viewed as “super-correlation” which can induce classical correlation when considering a ternary or larger system.
The impact of contractual savings institutions on securities markets

The authors assess empirically the impact of contractual savings institutions portfolios (pension funds and life insurance companies) on securities markets, for example, depth and liquidity in the domestic stock market, and depth in the domestic bond market. They discuss how the institutionalization of savings can modify financial markets through the lengthening of securities' maturities. The results are the following: 1) An increase in assets of contractual savings institutions relative to domestic financial assets has a positive impact on the depth of stock and bond markets on average. 2) The impact on stock market depth and liquidity is nonlinear: it is stronger in countries where corporate information is more transparent. 3) There is evidence of a significant heterogeneity among countries: contractual savings have a stronger impact on securities markets in countries where the financial system is market based, pension fund contributions are mandatory, and international transactions in securities are lower. 4) The authors do not find that the impact of contractual savings institutions on securities markets is explained by the overall level of development, education, demographic structure or the legal environment.
On the formation of the counter-rotating vortex pair in transverse jets

Among the important physical phenomena associated with the jet in crossflow is the formation and evolution of vortical structures in the flow field, in particular the counter-rotating vortex pair (CVP) associated with the jet cross-section. The present computational study focuses on the mechanisms for the dynamical generation and evolution of these vortical structures. Transient numerical simulations of the flow field are performed using three-dimensional vortex elements. Vortex ring rollup, interactions, tilting, and folding are observed in the near field, consistent with the ideas described in the experimental work of Kelso, Lim & Perry (1996), for example. The time-averaged effect of these jet shear layer vortices, even over a single period of their evolution, is seen to result in initiation of the CVP. Further insight into the topology of the flow field, the formation of wake vortices, the entrainment of crossflow, and the effect of upstream boundary layer thickness is also provided in this study.
ITS Tools for Natural Language Dialogue: A Domain-Independent Parser and Planner

The goal of the Atlas project is to increase the opportunities for students to construct their own knowledge by conversing (in typed form) with a natural language-based ITS. In this paper we describe two components of Atlas|APE, the integrated planning and execution system at the heart of Atlas, and CARMEL, the natural language understanding component. These components have been designed as domain-independent rule-based software, with the goal of making them both extensible and reusable. We illustrate the use of CARMEL and APE by describing Atlas-Andes, a prototype ITS built with Atlas using the Andes physics tutor as the host.
Opioids modulate stress-induced proenkephalin gene expression in the hypothalamus of transgenic mice: a model of endogenous opioid gene regulation by exogenous opioids

Stressful stimuli strongly induce proenkephalin gene expression within the paraventricular nucleus (PVN) of the hypothalamus. A human proenkephalin-beta-galactosidase fusion gene has previously been shown to give correct phenotypic expression and appropriate stress regulation within the hypothalamus of transgenic mice; this model provides high sensitivity, cellular resolution, and ready quantification of levels of proenkephalin gene expression. Here we describe use of this transgenic model to study modulation of stress-regulated gene expression in the PVN by opiates. Acute or subacute morphine administration prior to a hypertonic saline stress produced marked superinduction of transgene expression compared with hypertonic saline stress alone. In contrast, chronic morphine administration decreased basal expression of the transgene, and inhibited stress-induced expression of the transgene. The endogenous proenkephalin mRNA was induced in parallel with the transgene as demonstrated by in situ hybridization; the immediate-early gene c-fos was also regulated in parallel with the transgene. These data suggest that acute or subacute morphine administration sensitizes proenkephalin neurons within the PVN and other regions of the hypothalamus to stress and that chronic morphine administration desensitizes this response. Because the molecular mechanisms regulating the expression of the transgene are well understood, this model provides a useful tool for investigating cellular and molecular effects of opioids on the hypothalamus.
From random walks to distances on unweighted graphs

Large unweighted directed graphs are commonly used to capture relations between entities. A fundamental problem in the analysis of such networks is to properly define the similarity or dissimilarity between any two vertices. Despite the significance of this problem, statistical characterization of the proposed metrics has been limited. We introduce and develop a class of techniques for analyzing random walks on graphs using stochastic calculus. Using these techniques we generalize results on the degeneracy of hitting times and analyze a metric based on the Laplace transformed hitting time (LTHT). The metric serves as a natural, provably well-behaved alternative to the expected hitting time. We establish a general correspondence between hitting times of the Brownian motion and analogous hitting times on the graph. We show that the LTHT is consistent with respect to the underlying metric of a geometric graph, preserves clustering tendency, and remains robust against random addition of non-geometric edges. Tests on simulated and real-world data show that the LTHT matches theoretical predictions and outperforms alternatives.
The curious case of Brazil's closedness to trade

Although Brazil has become one of the largest economies in the world, it remains among the most closed economies as measured by the share of exports and imports in gross domestic product. This feature cannot be explained simply by the size of Brazil's economy. Rather, it is due to an economic structure reliant on domestic value chain integration as opposed to participation in global production networking. It also reflects more generally an export base that shows lack of dynamism. Opening up and moving toward integration into global value chains could produce efficiency gains and help Brazil address its productivity and competitiveness challenges.
Burn‐in Testing: Its Quantification and Applications

Early life failures are usually attributed to problems in the manufacturing, packaging, and assembling phases. After making improvements to the greatest possible extent in these phases, the only way to improve the product's reliability is to eliminate defective units before they reach customers. A common approach used to weed out defective and weak parts before shipping the products to customers is burn-in testing. Burn-in testing has become a frequently used procedure in many industries, especially the semiconductor industry. In this article, an overview of burn-in testing is presented and its applications are explained. Burn-in methods are related to a variety of failure mechanisms and the conditions under which the tests are run are specified. Finally, the burn-in time is determined through a reliability bathtub curve model to be the time after which the failure rate remains constant. Keywords: burn-in testing; bathtub curve; reliability; failure rate; burn-in time determination; useful life; test conditions
Solving cooperative reliability games

Cooperative games model the allocation of profit from joint actions, following considerations such as stability and fairness. We propose the reliability extension of such games, where agents may fail to participate in the game. In the reliability extension, each agent only "survives" with a certain probability, and a coalition's value is the probability that its surviving members would be a winning coalition in the base game. We study prominent solution concepts in such games, showing how to approximate the Shapley value and how to compute the core in games with few agent types. We also show that applying the reliability extension may stabilize the game, making the core non-empty even when the base game has an empty core.
Image Restoration With A Locally Variable Wiener Filter

The parametric Wiener filter is often used to deblur images that are relatively noise-free. If noise is more severe, the restored image may be obscured by a granular pattern that results when the noise is subjected to the deblurring filter. This effect may be reduced by using a larger noise parameter, but this leads to a restoration that is less sharp. We describe how the noise parameter may be varied from pixel to pixel, so that it is larger only where noise is greater. Pixels with low signal-to-noise ratios are identified by a thresholding process and by comparison with nearest neighbors. The effects of the estimated Wiener spectra on the restored image are discussed.
A historical fluence analysis of the radiation environment of the Chandra X-ray Observatory and implications for continued radiation monitoring

Now in operation for over 6 years, the Chandra X-ray Observatory (CXO) has sampled a variety of space environments. Its highly elliptical orbit, with a 63.5 hr period, regularly takes the spacecraft through the Earth's radiation belts, the magnetosphere, the magnetosheath and into the solar wind. Additionally, the CXO has weathered several severe solar storms during its time in orbit. Given the vulnerability of Chandra's Charge Coupled Devices (CCDs) to radiation damage from low energy protons, proper radiation management has been a prime concern of the Chandra team. A comprehensive approach utilizing scheduled radiation safing, in addition to both on-board autonomous radiation monitoring and manual intervention, has proved successful at managing further radiation damage. However, the future of autonomous radiation monitoring on-board the CXO faces a new challenge as the multi-layer insulation (MLI) on its radiation monitor, the Electron, Proton, Helium Instrument (EPHIN), continues to degrade, leading to elevated temperatures. Operating at higher temperatures, the data from some EPHIN channels can become noisy and unreliable for radiation monitoring. This paper explores the full implication of the loss of EPHIN to CXO radiation monitoring by evaluating the fluences the CXO experienced during 40 autonomous radiation safing events from 2000 through 2005 in various hypothetical scenarios which include the use of EPHIN in limited to no capacity as a radiation monitor. We also consider the possibility of replacing EPHIN with Chandra's High Resolution Camera (HRC) for radiation monitoring.
Memory effects in the frictional damping of diffusive and vibrational motion of adatoms

We investigate the memory effects in the frictional damping of the vibrational and diffusive motion of an adatom. Using the molecular-dynamics simulation method, we solve the equations of motion of an adatom in a periodic potential coupled to substrate phonons which are in turn coupled to a heat bath. The frustrated translational mode and the diffusion constant of the adatom is studied by calculating appropriate time-dependent correlation functions. We discuss our numerical results in the context of a generalized Langevin equation. The validity of analytic approximations to the memory function in the Langevin equation such as mode-mode coupling and initial value approximation are examined by comparing the analytic results with those obtained from the numerical simulations. \textcopyright{} 1996 The American Physical Society.
THE SHAPES OF MOLECULAR CLOUD CORES IN SIMULATIONS AND OBSERVATIONS

In this study, we investigate the shapes of starless and protostellar cores using hydrodynamic, self-gravitating adaptive mesh refinement simulations of turbulent molecular clouds. We simulate observations of these cores in dust emission, including realistic noise and telescope resolution, and compare to the observed core shapes measured in Orion by Nutter & Ward-Thompson (2007). The simulations and the observations have generally high statistical similarity, with particularly good agreement between simulations and Orion B. Although protostellar cores tend to have semi-major axis to semi-minor axis ratios closer to one, the distribution of axis ratios for starless and protostellar cores is not significantly different for either the actual observations of Orion or the simulated observations. Because of the high level of agreement between the non-magnetic hydrodynamic simulations and observation, contrary to a number of previous authors, one cannot infer the presence of magnetic fields from core shape distributions.
Shock unsteadiness in a reattaching shear layer

The origin of shock unsteadiness in a Mach 2.9 turbulent reattaching shear layer was investigated experimentally using temporally resolved flow visualization and measurements of wall pressure fluctuations. In this flow, the separation point of a turbulent boundary layer is essentially fixed at a backward-facing step, and the reattachment point is free to move along a ramp. In order to examine the influence of disturbances originating in the incoming shear layer, artificial disturbances were introduced into the flow through steady air injection in the vicinity of separation. The effect on the reattachment shock system was dramatic: the intensity of the pressure fluctuations and the amplitude of the shock motion increased substantially, and power spectra of the pressure fluctuations showed a distinct shift to lower frequency. The spectra collapsed onto a common curve in non-dimensional coordinates based on a length scale derived from two-point cross-correlations of the flow visualization data and a convection velocity derived from cross-correlations of the pressure measurements. The data were compared to a theory developed by Plotkin (1975), which is based on perturbation of a shock by random fluctuations in the incoming turbulent flow. Plotkin's model mimics the manner in which relatively broad-band perturbations in the incoming turbulent flow lead to relatively low-frequency motion of the separation bubble and its associated shock system. It is an excellent fit to separation shock motion, such as that generated in a blunt fin flow (briefly illustrated here). In the present shear layer flow, this low-frequency motion was detectable in the spectra near reattachment, but contained considerably less energy relative to the shock motions caused by direct perturbations by the incoming turbulent structures. These results indicate that the shock motion in the reattaching shear layer is primarily caused by organized structures in the incoming turbulent flow.
Ferromagnetic, A -Type, and Charge-Ordered CE -Type States in Doped Manganites Using Jahn-Teller Phonons

The two-orbital model for manganites with both noncooperative and cooperative Jahn-Teller phonons is studied at hole density x = 0.5 using Monte Carlo techniques. The phase diagram is obtained by varying the electron-phonon coupling and the t(2g)-spins exchange. The insulating CE-type charge- and orbital-ordered state with the z-axis charge stacking observed in narrow-bandwidth manganites is stabilized in the simulations. Its charge gap Delta(CO) is much larger than the critical temperature k(B)T(CO). Metalliclike A-type and ferromagnetic states are also obtained in the same framework, and the phase boundaries among them have first-order characteristics.
Rotational response and slip prediction of serpentine belt drive systems

A nonlinear model is developed which describes the rotational response of automotive serpentine belt drive systems. Serpentine drives utilize a single {long) belt to drive all engine accessories from the crankshaft. An equilibrium analysis leads to a closedform procedure for determining steady-state tensions in each belt span. The equations of motion are linearized about the equilibrium state and rotational mode vibration characteristics are determined from the eigenvalue problem governing free response. Numerical solutions of the nonlinear equations of motion indicate that, under certain engine operating conditions, the dynamic tension fluctuations may be sufficient to cause the belt to slip on particular accessory pulleys. Experimental measurements of dynamic response are in good agreement with theoretical results and confirm theoretical predictions of system vibration, tension fluctuations, and slip.
Water laws and concepts

A publication on water management of the National Academy of Sciences [1966, 38] contains the following statement: In the public allocation process it is unlikely that society will welcome widepread and strict allocation of water. Water is regarded as a birthright of Americans—a common holding in which there are common stakes. Other commodities are not so regarded; water is singled out for special consideration. This statement is an expression of human rights without qualification as to property or economic status. It also implies that people have rights to water suitable and adequate to their needs wherever they may be.
Ring-based analogues of pentamidine versus P. carinii pneumonia in culture

Abstract The synthesis of aromatic ring-based pentamidine analogues, in which the aliphatic bridge has been replaced by benzene, pyridine, or pyrimidine has been accomplished in two steps. Compounds containing benzene and pyridine as the central core of the molecule have demonstrated activity against PCP in culture.
Broad and Shifted Iron-Group Emission Lines in Gamma-Ray Bursts as Tests of the Hypernova Scenario

In the hypernova/collapsar model of γ-ray bursts, it is natural that radiation is emitted by the inner engine for some time after the burst. This has been discussed as a possible source of the X-ray line emission observed in some afterglows. We show here that the natural geometry of a hypernova—a source of radiation at the bottom of a deep funnel—has very significant consequences for the shape and central energy of the observed emission lines; the lines acquire a very broad scattering wing on the low-energy side and a characteristic second peak 1 Compton wavelength away from the initial energy due to the once- and twice-scattered photons. We suggest that this explains the large width of the observed lines. Furthermore, the downscattering lowers the central line energy (by up to 1 keV in the source rest frame, before the lines become unrecognizable) so that the observed line energies can become consistent with originating from cobalt and nickel, as expected in few-day-old supernova ejecta.
Regularity and the Cesàro–Nevai class

We consider OPRL and OPUC with measures regular in the sense of Ullman-Stahl-Totik and prove consequences on the Jacobi parameters or Verblunsky coefficients. For example, regularity on [-2,2] implies limN→∞N-1[Σ Nn=1(an-1)2 + b2n] = 0.
Synthesis of pyridazines functionalized with amino acid side chains

Abstract A simple route for the preparation of 3,4,6-substituted pyridazines is described by using Tebbe olefination of esters then Diels–Alder reaction of the resulting enol ethers with tetrazine.
Two-photon interference without bunching two photons

Abstract We report an experiment which conclusively demonstrates that the two-photon entangled state interference cannot be pictured as the overlap and ‘bunching’ of two individual photons on a beamsplitter. We also demonstrate that photon ‘bunching’ does not occur if the two-photon Feynman amplitudes are distinguishable, even though individual photons do overlap on a beamsplitter.
Radiative damping of gravity waves in the solar atmosphere

The nonlocal character of the radiation field sianificantly modifies the radiative damping of perturbations in the solar photosphere. Gravity waves are not usually considered to exist in the solar photosphere because the radiative damping time, when based on the Newtonian approximation, is too short. However, this restriction does not apply to low order gravity waves. In fact, with the inclusion of nonlocal effects, the radiative damping for low order gravity waves becomes negative for some region in the photosphere and thus acts as a driving mechanism for gravity waves there.
Do internists and emergency physicians agree on the appropriateness of emergency department visits

The purpose of this study was to determine the levels of agreement between three methods of assessing appropriateness of emergency department (ED) visits. In particular, we tested the agreement between internists and emergency physicians reviewing the ED nurses’ triage notes, containing information that might be available by telephone to an internist. For 892 adult patient ED visits reviewed, we found only moderate agreement (κ = 0.47) between these groups. In cases of disagreement, emergency physicians were 10.3 times more likely than internists to classify those with minor discharge diagnoses as appropriate for ED care. As managed care grows, the determination of ED appropriateness may depend on open discussions between physician groups, as well as on access to timely care in office settings.
Seltene akute Krankheitsbilder der oberen Atemwege bei Kindern

The radiologist should recognize dangerous uncommon conditions such as epiglottitis and membranous croup by their pattern on conventional images. Subglottic narrowing, as from croup, is recognizable on lateral images by loss of the superior interface of trachea and vocal cords. A lateral image is important when an upper esophageal foreign body is seen on a frontal view.