cssi/SciSciGPT-SciSciNet huggingface dataset:
X-ray flares from propagation instabilities in long gamma-ray burst jets

We present a numerical simulation of a gamma-ray burst jet from a long-lasting engine in the core of a 16 solar mass Wolf–Rayet star. The engine is kept active for 6000 s with a luminosity that decays in time as a power law with index −5/3. Even though there is no short time-scale variability in the injected engine luminosity, we find that the jet’s kinetic luminosity outside the progenitor star is characterized by fluctuations with relatively short time-scale. We analyse the temporal characteristics of those fluctuations and we find that they are consistent with the properties of observed flares in X-ray afterglows. The peak-to-continuum flux ratio of the flares in the simulation is consistent with some, but not all, the observed flares. We propose that propagation instabilities, rather than variability in the engine luminosity, are responsible for the X-ray flares with moderate contrast. Strong flares such as the one detected in GRB 050502B, instead, cannot be reproduced by this model and require strong variability in the engine activity.
The role of social networks in online shopping: information passing, price of trust, and consumer choice

While social interactions are critical to understanding consumer behavior, the relationship between social and commerce networks has not been explored on a large scale. We analyze Taobao, a Chinese consumer marketplace that is the world's largest e-commerce website. What sets Taobao apart from its competitors is its integrated instant messaging tool, which buyers can use to ask sellers about products or ask other buyers for advice. In our study, we focus on how an individual's commercial transactions are embedded in their social graphs. By studying triads and the directed closure process, we quantify the presence of information passing and gain insights into when different types of links form in the network.Using seller ratings and review information, we then quantify a price of trust. How much will a consumer pay for transaction with a trusted seller? We conclude by modeling this consumer choice problem: if a buyer wishes to purchase a particular product, how does (s)he decide which store to purchase it from? By analyzing the performance of various feature sets in an information retrieval setting, we demonstrate how the social graph factors into understanding consumer behavior.
A Lambda Calculus for Quantum Computation

The classical lambda calculus may be regarded both as a programming language and as a formal algebraic system for reasoning about computation. It provides a computational model equivalent to the Turing machine and continues to be of enormous benefit in the classical theory of computation. We propose that quantum computation, like its classical counterpart, may benefit from a version of the lambda calculus suitable for expressing and reasoning about quantum algorithms. In this paper we develop a quantum lambda calculus as an alternative model of quantum computation, which combines some of the benefits of both the quantum Turing machine and the quantum circuit models. The calculus turns out to be closely related to the linear lambda calculi used in the study of linear logic. We set up a computational model and an equational proof system for this calculus, and we argue that it is equivalent to the quantum Turing machine.
Inequality, Interactions, and Human Development

Abstract The Human Development Index, which is multidimensional by construction, is criticized on the ground that it is insensitive to any form of inequality across persons. Inequality in the multidimensional context can take two distinct forms. The first pertains to the spread of the distribution across persons, analogous to unidimensional inequality. The second, in contrast, deals with interactions among dimensions. The second form of inequality is important as dimensional interactions may alter individual level evaluations as well as overall inequality. Recently proposed indices have incorporated only the first form of inequality, but not the second. It is an important omission. This paper proposes a two‐parameter class of Human Development Indices that reflects sensitivity to both forms of inequality. It is revealed how consideration of interactions among dimensions affects policy recommendations. Finally, the indices are applied to the year 2000 Mexican census data to contrast the present approach wi...
Selectivity and Market Timing Performance of Fidelity Sector Mutual Funds

In this paper, we test the selectivity and timing performance of the Fidelity sector mutual funds during the 1989–1998 time period. We use the S&P 500, the Dow Jones Industry Group Total Return Indexes, and the Dow Jones Subgroup Total Return Indexes as benchmarks. When we use the Dow Jones Industry benchmarks, our results indicate that many sector fund managers have positive selectivity but negative timing ability. We also find that the results are sensitive to our choice of benchmark and timing model.
Cultural Intelligence and International Leadership Potential: The Importance of Contact for Members of the Majority

Integrating distinctiveness theory and contact theory, we develop a conceptual model proposing that prior intercultural contact has mediated effects on international leadership potential via cultural intelligence—but that these effects are stronger for majorities. Results of two samples of working adults, using both self-report (n = 441, Study 1) and matched employee-observer (n = 181, Study 2) data provide strong support for the model. Cultural intelligence mediates the effects of prior intercultural contact on international leadership potential. Further, moderated mediation analyses demonstrate that cultural intelligence mediates the relationship between prior intercultural contact and international leadership potential for majorities, but not for minorities. The current study offers contributions to theory and practice in at least two ways. First, the proposed model is theoretically important because it provides a more complete picture of predictors of international leadership potential and it reconciles prior inconsistent findings by showing the mediating role of cultural intelligence and moderating role of minority status. Second, the study adds to the increasing evidence suggesting that prior intercultural contact and cultural intelligence are meaningful criteria for developing international leaders. More important, results show that prior intercultural contact is especially important for majorities.
Energy inequalities for a model of wave propagation in cold plasma

Energy inequalities are derived for an elliptic-hyperbolic operator arising in plasma physics. These inequalities imply the existence of distribution and weak solutions to various closed boundary-value problems. An existence theorem is proven for a related class of Keldysh equations, and the failure of expected methods for obtaining uniqueness is discussed. The proofs use ideas recently introduced by Lupo, Morawetz, and Payne for a generalized Tricomi operator. The existence of strong solutions under open boundary conditions is also proven.
How We Refactor, and How We Know It

Refactoring is widely practiced by developers, and considerable research and development effort has been invested in refactoring tools. However, little has been reported about the adoption of refactoring tools, and many assumptions about refactoring practice have little empirical support. In this paper, we examine refactoring tool usage and evaluate some of the assumptions made by other researchers. To measure tool usage, we randomly sampled code changes from four Eclipse and eight Mylyn developers and ascertained, for each refactoring, if it was performed manually or with tool support. We found that refactoring tools are seldom used: 11 percent by Eclipse developers and 9 percent by Mylyn developers. To understand refactoring practice at large, we drew from a variety of data sets spanning more than 39,000 developers, 240,000 tool-assisted refactorings, 2,500 developer hours, and 12,000 version control commits. Using these data, we cast doubt on several previously stated assumptions about how programmers refactor, while validating others. Finally, we interviewed the Eclipse and Mylyn developers to help us understand why they did not use refactoring tools and to gather ideas for future research.
ON THE DYNAMIC STABILITY OF COOL SUPERGIANT ATMOSPHERES

We have developed a new formalism to compute the thermodynamic coefficient Γ1 in the theory of stellar and atmospheric stability. We generalize the classical derivation of the first adiabatic index, which is based on the assumption of thermal ionization and equilibrium between gas and radiation temperature, toward an expression that incorporates photoionization due to radiation with a temperature Trad different from the local kinetic gas temperature. Our formalism considers the important non-LTE conditions in the extended atmospheres of supergiant stars. An application to the Kurucz grid of cool supergiant atmospheres demonstrates that models with Trad Teff between 6500 and 7500 K become most unstable against dynamic perturbations, according to Ledoux' stability integral Γ1. This results from Γ1 and Γ1 acquiring very low values, below 4/3, throughout the entire stellar atmosphere, which causes very high gas compression ratios around these effective temperatures. Based on detailed non-LTE calculations, we discuss atmospheric instability of pulsating massive yellow supergiants, such as the hypergiant ρ Cas (Ia+), which exist in the extension of the Cepheid instability strip, near the Eddington luminosity limit.
Implementation and extensibility of an analytic placer

Automated cell placement is a critical problem in very large scale integration (VLSI) physical design. New analytical placement methods that simultaneously spread cells and optimize wirelength have recently received much attention from both academia and industry. A novel and simple objective function for spreading cells over the placement area is described in the patent of Naylor et al. (U.S. Pat. 6301693). When combined with a wirelength objective function, this allows efficient simultaneous cell spreading and wirelength optimization using nonlinear optimization techniques. In this paper, we implement an analytic placer (APlace) according to these ideas (which have other precedents in the open literature), and conduct in-depth analysis of characteristics and extensibility of the placer. Our contributions are as follows. 1) We extend the objective functions described in (Naylor et al., U.S. Patent 6301693) with congestion information and implement a top-down hierarchical (multilevel) placer (APlace) based on them. For IBM-ISPD04 circuits, the half-perimeter wirelength of APlace outperforms that of FastPlace, Dragon, and Capo, respectively, by 7.8%, 6.5%, and 7.0% on average. For eight IBM-PLACE v2 circuits, after the placements are detail-routed using Cadence WRoute, the average improvement in final wirelength is 12.0%, 8.1%, and 14.1% over QPlace, Dragon, and Capo, respectively. 2) We extend the placer to address mixed-size placement and achieve an average of 4% wirelength reduction on ten ISPD'02 mixed-size benchmarks compared to results of the leading-edge solver, FengShui. 3) We extend the placer to perform timing-driven placement. Compared with timing-driven industry tools, evaluated by commercial detailed routing and static timing analysis, we achieve an average of 8.4% reduction in cycle time and 7.5% reduction in wirelength for a set of six industry testcases. 4) We also extend the placer to perform input/output-core coplacement and constraint handing for mixed-signal designs. Our paper aims to, and empirically demonstrates, that the APlace framework is a general, and extensible platform for "spatial embedding" tasks across many aspects of system physical implementation.
Complex modes in damped sandwich beams using beam and elasticity theories

We investigated complex damped modes in beams in the presence of a viscoelastic layer sandwiched between two elastic layers. The problem was solved using two approaches, (1) Rayleigh beam theory and analyzed using the Ritz method, and (2) by using 2D plane stress elasticity based finite-element method. The damping in the layers was modeled using the complex modulus. Simply-supported, cantilever, and viscously supported boundary conditions were considered in this study. Simple trigonometric functions were used as admissible functions in the Ritz method. The key idea behind sandwich structure is to increase damping in a beam as affected by the presence of a highly-damped core layer vibrating mainly in shear. Different assumptions are utilized in the literature, to model shear deformation in the core layer. In this manuscript, we used FEM without any kinematic assumptions for the transverse shear in both the core and elastic layers. Moreover, numerical examples were studied, where the base and constraining layers were also damped. The loss factor was calculated by modal strain energy method, and by solving a complex eigenvalue problem. The efficiency of the modal strain energy method was tested for different loss factors in the core layer. Complex mode shapes of the beam were also examined in the study, and a comparison was made between viscoelastically and viscously damped structures. The numerical results were compared with those available in the literature, and the results were found to be satisfactory.
Bond Thickness Effects upon Stresses in Single-Lap Adhesive Joints

Results of an analytical investigation on the influence of bond thickness upon the stress distribution in singlelap adhesive joints are presented. The present work extends the basic approach for bonded joints, orginally introduced by Goland and Reissner, through use of a more complete shear-strain/displacement equation for the adhesive layer. This refinement was not found to be included in any of the numerous analytical investigations reviewed. As a result of the approach employed, the present work uncovers several interesting phenomena without adding any significant complication to the analysis. Besides modifying some coefficients in the shear stress equations, completely new terms in the differential equation and boundary conditions for bond peel stress are obtained. Sn addition, a variation of shear stress through the bond thickness, no matter how thin it may be, is analytically predicted only by the present theory. This through-the-bond-thickness variation of shear stress identifies two antisymmetrical adherend-bond interface points at which the shear stresses are highest. The growth of joint failures originating from these points agrees with results obtained from actual experiments.
Thermodynamic conditions for the synthesis of oxide superconductors

Abstract The conditions for existence and preparation of superconductors are investigated from a thermodynamic point of view. It is illustrated on selected examples that the final electronically important preparative condition for oxide superconductivity corresponds to an annealing step in air near 1000 K. It is shown that this is connected with the requirement of a component metal, M, which changes its oxidation state according to Mn/n′ as indicated by the decomposition of its elemental oxides in the range around 1000 K. Examples are Tl2O/Tl2O3 or CuO versus a fictitious Cu2O3. A second basic requirement is O− formation according to the redox couple O2−/− which also can occur near 1000 K but not much above. Accordingly, it is made plausible that only a limited number of M can produce oxide superconductivity. Implications for the mechanism of superconductivity are discussed.
In-operando synchronous time-multiplexed O K-edge x-ray absorption spectromicroscopy of functioning tantalum oxide memristors

Memristors are receiving keen interest because of their potential varied applications and promising large-scale information storage capabilities. Tantalum oxide is a memristive material that has shown promise for high-performance nonvolatile computer memory. The microphysics has been elusive because of the small scale and subtle physical changes that accompany conductance switching. In this study, we probed the atomic composition, local chemistry, and electronic structure of functioning tantalum oxide memristors through spatially mapped O K-edge x-ray absorption. We developed a time-multiplexed spectromicroscopy technique to enhance the weak and possibly localized oxide modifications with spatial and spectral resolutions of <30 nm and 70 meV, respectively. During the initial stages of conductance switching of a micrometer sized crosspoint device, the spectral changes were uniform within the spatial resolution of our technique. When the device was further driven with millions of high voltage-pulse cycles, ...
When not enough is too much: the role of insufficient glucocorticoid signaling in the pathophysiology of stress-related disorders

OBJECTIVE: Previous theories have emphasized the role of excessive glucocorticoid activity in the pathology of chronic stress. Nevertheless, insufficient glucocorticoid signaling (resulting from de...
Control Strategies for Transit Priority

Control strategies for transit priority have long been recognized as having the potential to improve traffic performance for transit vehicles, which could also lead to improved schedule reliability, reduced operating costs, and greater ridership. However, there have been relatively few successful implementations of transit priority measures on urban networks with signalized intersections in coordinated signal systems. Existing control strategies are reviewed, the major factors affecting transit priority are identified, and the formulation of both passive and active transit priority strategies for arterials with coordinated traffic signals are described. The proposed strategies were evaluated on a real-life arterial corridor. The proposed passive and active priority strategies placed major emphasis on the systemwide improvements to the transit movements and on minimization of the adverse impacts to the rest of the traffic stream. The criteria used to grant priority include the availability of spare green t...
Phase-only analog encoding for a multi-antenna fusion center

We consider a distributed sensor network in which the single antenna sensor nodes observe a deterministic unknown parameter and after encoding the observed signal with a phase parameter, the sensor nodes transmit it simultaneously to a multi-antenna fusion center (FC). The FC optimizes the phase encoding parameter and feeds it back to the sensor nodes such that the variance of estimation error can be minimized. We relax the phase optimization problem to a semidefinite programming (SDP) problem and the numerical results show that the performance of the proposed method is close to the theoretical bound. Also, asymptotic results show that when the number of sensors is very large and the variance of the distance between the sensor nodes and FC is small, multiple antennas do not provide a benefit compared with a single antenna system; when the number of antennas M is large and the measurement noise at the sensor nodes is small compared with the additive noise at the FC, the estimation error variance can be reduced by a factor of M.
Fair scheduling in wireless packet networks

Fair scheduling of delay and rate-sensitive packet flows over a wireless channel is not addressed effectively by most contemporary wireline fair-scheduling algorithms because of two unique characteristics of wireless media: (1) bursty channel errors and (2) location-dependent channel capacity and errors. Besides, in packet cellular networks, the base station typically performs the task of packet scheduling for both downlink and uplink flows in a cell; however, a base station has only a limited knowledge of the arrival processes of uplink flows. We propose a new model for wireless fair-scheduling based on an adaptation of fluid fair queueing (FFQ) to handle location-dependent error bursts. We describe an ideal wireless fair-scheduling algorithm which provides a packetized implementation of the fluid mode, while assuming full knowledge of the current channel conditions. For this algorithm, we derive the worst-case throughput and delay bounds. Finally, we describe a practical wireless scheduling algorithm which approximates the ideal algorithm. Through simulations, we show that the algorithm achieves the desirable properties identified in the wireless FFQ model.
Alternative energy input: mechanochemical, microwave and ultrasound-assisted organic synthesis

Microwave, ultrasound, sunlight and mechanochemical mixing can be used to augment conventional laboratory techniques. By applying these alternative means of activation, a number of chemical transformations have been achieved thereby improving many existing protocols with superior results when compared to reactions performed under traditional conditions. The purpose of this critical review is to highlight the advances in this general area by presenting such newer applications in organic synthesis (175 references).
AIDS, homophobia and biomedical discourse: An epidemic of signification

(1987). AIDS, homophobia and biomedical discourse: An epidemic of signification. Cultural Studies: Vol. 1, No. 3, pp. 263-305.
Environmental control of tuberculosis

The premise of this article is that it is possible to reduce but not eliminate the risk of TB infection in many institutional settings through environmental interventions--as supplements to conventional public health TB control efforts. Of the environmental means available to reduce the concentration of infectious droplet nuclei, ventilation, isolation strategies, and personal respirators have received the most attention, but each has inherent limitations. Ventilation and other air-moving strategies (i.e., fan-filter and fan-UV room units) are limited by the large volume of air that must be moved to dilute and remove already dilute droplet nuclei. Isolation assumes that potential transmitters are suspected, whereas negative pressure in isolation rooms is difficult to achieve and maintain in many hospitals. The use of well-designed small enclosures for sputum induction and other high-risk procedures, however, should provide highly effective source control. Personal respirators have a limited protective role because they cannot be worn by all workers at all times, and cannot reasonably be issued to other patients and visitors. Germicidal UV irradiation of upper room air is widely misunderstood, but offers practical air disinfection that can be safely and efficiently deployed in a variety of high-risk environments. Although there are theoretical and experimental bases for these recommendations, there are no clinical field trials preventing TB using any of the available environmental interventions, primarily because of the highly variable nature of TB transmission.
Carbon allowances and the demand for offsets: a comprehensive assessment of imperfect substitutes

The efficient use of market-based policy instruments is an area of increasing importance as scholars and policymakers work to balance effective climate policy with economic growth. Carbon allowances and carbon offsets, despite being statutorily substitutable, behave in practice like imperfect substitutes. This paper provides a synthesis of extant work, market data and the regulatory frameworks of the world’s major carbon markets, and provides a comprehensive assessment of the drivers of demand for carbon offsets. It also provides a detailed assessment of the process through which international carbon offsets are produced, the UN’s Clean Development Mechanism. Demand for carbon offsets is heavily influenced by key programme design parameters that are specific to carbon market design and its implementation. These design parameters heavily influence the degree to which transaction costs, regulatory uncertainty and risk factor into the decisions of firms operating within the carbon trading programme. This paper also identifies key extra-statutory drivers that are outside of the policymaker’s control, which should be considered in both the policy design and the implementation process. This paper provides an instructive set of guiding criteria for policymakers and scholars for the design of future market-based environmental policy.
Ligand Effects on the Chemoselectivity of Transition Metal Catalyzed Reactions of α‐Diazo Carbonyl Compounds

The transition metal catalyzed reaction of α-diazo carbonyl compounds has found numerous applications in organic synthesis, and its use in either heterocyclic or carbocyclic ring formation is well precedented. Early work in this area made use of insoluble copper catalysts. Although these catalysts are still employed today, their use has decreased significantly with the advent of homogeneous copper catalysts and catalysts based on other metals. The discovery that RhII carboxylates facilitate nitrogen loss from diazo compounds rekindled significant interest in the field of diazo/carbenoid chemistry. Since the realization that RhII carboxylates are superior catalysts for the generation of transient electrophilic metal carbenoids from α-diazo carbonyl compounds, intramolecular carbenoid addition and insertion reactions have assumed strategic importance in CC bond-forming reactions in organic synthesis. In contrast to other catalysts that are suitable for carbenoid reactions of diazo compounds, those constructed with the dirhodium(II) framework are most amenable to ligand modifications that, in turn, can influence reaction selectivity. This article will emphasize the chemical behavior of transition metal carbenoid complexes that are greatly affected by the nature of the ligand groups attached to the metal center. Much of the discussion will center on the ability of the dirhodium(II) ligands to determine reaction preference toward different functional groups on the same molecule.
Kinetic Monte Carlo Simulation of Strained Heteroepitaxial Growth with Intermixing

An efficient method for the simulation of strained heteroepitaxial growth with intermixing using kinetic Monte Carlo is presented. The model used is based on a solid-on-solid bond counting formulation in which elastic effects are incorporated using a ball and spring model. While idealized, this model nevertheless captures many aspects of heteroepitaxial growth, including nucleation, surface diffusion, and long-range effects due to elastic interaction. The algorithm combines a fast evaluation of the elastic displacement field with an efficient implementation of a rejection-reduced kinetic Monte Carlo based on using upper bounds for the rates. The former is achieved by using a multigrid method for global updates of the displacement field and an expanding box method for local updates. The simulations show the importance of intermixing on the growth of a strained film. Further, the method is used to simulate the growth of self-assembled stacked quantum dots.
Toward an integrative perspective on resistance to change.

This article presents an integrative perspective on resistance. The phenomena of resistance can be seen at the behavioral, interpersonal, cognitive, and affective levels. A set of integrative working assumptions is proposed in which resistance reflects meaningful information about clients' conflicts among various aspects of their selves relating to change. In this view, resistance is determined by intrapersonal and interpersonal factors and can occur with or without conscious awareness. Integrative approaches to working with these conflicts are described. © 2002 John Wiley & Sons, Inc. J Clin Psychol/In Session 58: 219–227, 2002.
Cornering Light Stops with Dileptonic mT2

Supersymmetric spectra with a stop NLSP and a neutralino or gravitino LSP present a special challenge for collider searches. For stop pairs directly produced from QCD, the visible final-state particles are identical to those of top quark pair production, giving very similar kinematics but often with much smaller rates. The situation is exacerbated for compressed spectra with $ {m_{{\widetilde{t}}}}\simeq {m_t}+{m_{\mathrm{LSP}}} $ , as well as for lighter stops which can suffer from low acceptance efficiencies. In this note, we explore the power of a direct stop search using dileptonic m T2, similar to the one recently performed by ATLAS, but more optimized to cover these difficult regions of the ( $ {m_{{\widetilde{t}}}} $ , m LSP) plane. Our study accounts for the effects of stop chirality and LSP identity, which can be significant. In particular, our estimates suggest that $ {m_{{\widetilde{t}}}}={m_t} $ with a massless LSP is excludable for right-handed stops with bino-like (gravitino) LSP with 2012 (2011) data, but remains largely unobservable in the case of a higgsino-like singlino LSP. For each of these cases we map out the regions of parameter space that can be excluded with 2012 data, as well as currently allowed regions that would yield discovery-level significance. For the right-handed stop with bino-like LSP, we identify a narrow residual gap in coverage just above the compression line for any LSP mass, which will progressively close with more data and/or improved systematics. We also comment on the prospects of a precision m T2 shape measurement, and consider the potential of ATLAS’s dileptonic $ \widetilde{t}\to b\widetilde{\chi}_1^{+} $ searches when re-interpreted for light stops decaying directly to the LSP.
Reward-Based Transfer From Bottom-Up to Top-Down Search Tasks

Recent evidence has suggested that reward modulates bottom-up and top-down attentional selection and that this effect persists within the same task even when reward is no longer offered. It remains unclear whether reward effects transfer across tasks, especially those engaging different modes of attention. We directly investigated whether reward-based contingency learned in a bottom-up search task was transferred to a subsequent top-down search task, and probed the nature of the transfer mechanism. Results showed that a reward-related benefit established in a pop-out-search task was transferred to a conjunction-search task, increasing participants' efficiency at searching for targets previously associated with a higher level of reward. Reward history influenced search efficiency by enhancing both target salience and distractor filtering, depending on whether the target and distractors shared a critical feature. These results provide evidence for reward-based transfer between different modes of attention and strongly suggest that an integrated priority map based on reward information guides both top-down and bottom-up attention.
Ethanol Inhibits Some of the Early Effects of Epidermal Growth Factor in Vivo

Charles River male Wistar rats (200-300 g) were meal fed for 9-10 days, injected with either saline, epidermal growth factor (EGF), ethanol, or ethanol combined with EGF and their livers were freeze clamped 5 min after intraperitoneal injection of EGF. Metabolites were measured and the redox state and phosphorylation potential were calculated. Epidermal growth factor alone elevated hepatic content of glucose 1-P, glucose 6-P, fructose 6-P, and 3-phosphoglycerate 1.2-1.3-fold when compared to saline treatment. Ethanol alone decreased hepatic content of 3-phosphoglycerate and phosphoenolpyruvate 3.2-3.7-fold below saline-treated levels. Ethanol, in combination with EGF, decreased hepatic values for 3-phosphoglycerate and phosphoenolpyruvate 2.0-2.3-fold from saline treatment but elevated the content of phosphoenolpyruvate 1.6-fold over ethanol treatment alone. Epidermal growth factor inhibited pyruvate kinase activity 1.3-fold when compared to saline controls but ethanol in the presence of EGF facilitated the recovery of activity of this enzyme.
High power traveling wave amplifier experiments

Several high-power X-band traveling wave amplifiers have been fabricated and tested. The tubes have gains ranging from 13 dB to 32 dB at 8.76 GHz, and output powers ranging from 3 to 100 MW. The amplifiers are driven by the interaction of a slow space charge wave on an electron beam with an electromagnetic wave supported by the structure. The electron beam energy is 850 keV with currents in the 1-kA range. The amplifiers all operate in a single mode over a narrow frequency range. The amplifier gain increases rapidly with the beam current and with increases in the structure length. The amplifiers' main features are summarized. The experimental results presented confirm that it is possible to design and operate a high-power traveling-wave amplifier driven by a field emission generated intense electron beam. The system design enforced operation in the asymmetric TM01 mode of the amplifier, which showed no evidence of oscillation at the gains reported. >
A Local Circuit Model of Learned Striatal and Dopamine Cell Responses under Probabilistic Schedules of Reward

Recently, dopamine (DA) neurons of the substantia nigra pars compacta (SNc) were found to exhibit sustained responses related to reward uncertainty, in addition to the phasic responses related to reward-prediction errors (RPEs). Thus, cue-dependent anticipations of the timing, magnitude, and uncertainty of rewards are learned and reflected in components of DA signals. Here we simulate a local circuit model to show how learned uncertainty responses are generated, along with phasic RPE responses, on single trials. Both types of simulated DA responses exhibit the empirically observed dependencies on conditional probability, expected value of reward, and time since onset of the reward-predicting cue. The model's three major pathways compute expected values of cues, timed predictions of reward magnitudes, and uncertainties associated with these predictions. The first two pathways' computations refine those modeled by Brown et al. (1999). The third, newly modeled, pathway involves medium spiny projection neurons (MSPNs) of the striatal matrix, whose axons corelease GABA and substance P, both at synapses with GABAergic neurons in the substantia nigra pars reticulata (SNr) and with distal dendrites (in SNr) of DA neurons whose somas are located in ventral SNc. Corelease enables efficient computation of uncertainty responses that are a nonmonotonic function of the conditional probability of reward, and variability in striatal cholinergic transmission can explain observed individual differences in the amplitudes of uncertainty responses. The involvement of matricial MSPNs and cholinergic transmission within the striatum implies a relation between uncertainty in cue-reward contingencies and action-selection functions of the basal ganglia.
An expedient entry into the fused polycyclic skeleton of vannusal A

The synthesis of the fused polycyclic carbon framework of vannusal A is described; key features include inter- and intramolecular aldol reactions, a Mn(III) initiated radical cyclization, and a ring-closing olefin metathesis reaction.
SemInf: A Burst-Based Semantic Influence Model for Biomedical Topic Influence

In this study, we model how biomedical topics influence one another, given they are organized in a topic hierarchy, medical subject headings, in which the edges capture a parent-child/subsumption relationship among topics. This information enables studying influence of topics from a semantic perspective, which might be very important in analyzing topic evolution and is missing from the current literature. We first define a burst-based action for topics, which models upward momentum in popularity (or “elevated occurrences” of the topics), and use it to define two types of influence: accumulation influence and propagation influence. We then propose a model of influence between topics, and develop an efficient algorithm (TIPS) to identify influential topics. Experiments show that our model is successful at identifying influential topics and the algorithm is very efficient.
Introduction to Electrodynamics

This well-known undergraduate electrodynamics textbook is now available in a more affordable printing from Cambridge University Press. The Fourth Edition provides a rigorous, yet clear and accessible treatment of the fundamentals of electromagnetic theory and offers a sound platform for explorations of related applications (AC circuits, antennas, transmission lines, plasmas, optics and more). Written keeping in mind the conceptual hurdles typically faced by undergraduate students, this textbook illustrates the theoretical steps with well-chosen examples and careful illustrations. It balances text and equations, allowing the physics to shine through without compromising the rigour of the math, and includes numerous problems, varying from straightforward to elaborate, so that students can be assigned some problems to build their confidence and others to stretch their minds. A Solutions Manual is available to instructors teaching from the book; access can be requested from the resources section at www.cambridge.org/electrodynamics.
Augmenting the immersed boundary method with Radial Basis Functions (RBFs) for the modeling of platelets in hemodynamic flows

We present a new computational method by extending the Immersed Boundary (IB) method with a spectrally-accurate geometric model based on Radial Basis Function (RBF) interpolation of the Lagrangian structures. Our specific motivation is the modeling of platelets in hemodynamic flows, though we anticipate that our method will be useful in other applications as well. The efficacy of our new RBF-IB method is shown through a series of numerical experiments. Specifically, we compare our method with the traditional IB method in terms of convergence and accuracy, computational cost, maximum stable time-step size and volume loss. We conclude that the RBF-IB method has advantages over the traditional Immersed Boundary method, and is well-suited for modeling of platelets in hemodynamic flows.
The Effect of Dynamic and Static Choice Sets on Political Decision Making: An Analysis Using the Decision Board Platform

Previous studies of political decision making have used only “static” choice sets, where alternatives are “fixed” and are a priori known to the decision maker. We assess the effect of a dynamic choice set (new alternatives appear during the decision process) on strategy selection and choice in international politics. We suggest that decision makers use a mixture of decision strategies when making decisions in a two-stage process consisting of an initial screening of available alternatives, and a selection of the best one from the subset of remaining alternatives. To test the effects of dynamic and static choice sets on the decision process we introduce a computer-based “process tracer” in a study of top-ranking officers in the U.S. Air Force. The results show that (1) national security decision makers use a mixture of strategies in arriving at a decision, and (2) strategy selection and choice are significantly influenced by the structure of the choice set (static versus dynamic).
Enabling collaborative research using the Biomedical Informatics Research Network (BIRN)

Objective As biomedical technology becomes increasingly sophisticated, researchers can probe ever more subtle effects with the added requirement that the investigation of small effects often requires the acquisition of large amounts of data. In biomedicine, these data are often acquired at, and later shared between, multiple sites. There are both technological and sociological hurdles to be overcome for data to be passed between researchers and later made accessible to the larger scientific community. The goal of the Biomedical Informatics Research Network (BIRN) is to address the challenges inherent in biomedical data sharing. Materials and methods BIRN tools are grouped into ‘capabilities’ and are available in the areas of data management, data security, information integration, and knowledge engineering. BIRN has a user-driven focus and employs a layered architectural approach that promotes reuse of infrastructure. BIRN tools are designed to be modular and therefore can work with pre-existing tools. BIRN users can choose the capabilities most useful for their application, while not having to ensure that their project conforms to a monolithic architecture. Results BIRN has implemented a new software-based data-sharing infrastructure that has been put to use in many different domains within biomedicine. BIRN is actively involved in outreach to the broader biomedical community to form working partnerships. Conclusion BIRN’s mission is to provide capabilities and services related to data sharing to the biomedical research community. It does this by forming partnerships and solving specific, user-driven problems whose solutions are then available for use by other groups.
Substorms on Mercury

Qualitative similarities between some of the variations in the Mercury encounter data and variations in the corresponding regions of the earth's magnetosphere during substorms are pointed out. The Mariner 10 data on Mercury show a strong interaction between the solar wind and the plant similar to a scaled down version of that for the earth's magnetosphere. Some of the features observed in the night side Mercury magnetosphere suggest time dependent processes occurring there.
Articulation Node Based Routing in delay tolerant networks

Routing in delay tolerant networks (DTNs) is a challenging problem in networking research. Existing DTN routing solutions have used many approaches to increase the success rate of message delivery, such as meeting probabilities between nodes, packet replication and flooding. One important feature of these protocols is using local connection information to find the “best” path with high likelihood to deliver a packet. In this paper, we propose a new routing protocol called ANBR (Articulation Node Based Routing). From a global view, a general disconnected network can have many small instantaneously clustered mobile nodes. Mobility allows nodes carrying messages to deliver them to other clusters. Selecting appropriate nodes to carry and deliver messages becomes important in order to reduce message delay and overhead. The proposed ANBR tackles this issue by utilizing articulation nodes among a local sub-graph formed by including all neighbors of two “meeting” nodes. Articulation nodes are the articulation points or cut vertices of this local sub-graph, and by definition are the nodes, whose removal will disconnect the graph. Thus, these articulation nodes are more likely to be able to deliver messages outside the local cluster. Packets will be buffered in these nodes and forwarded to other articulation nodes when they meet. The process repeats until messages reach their destinations. We evaluate our algorithm by using real world data from the MIT reality mining project. The simulation results show that ANBR algorithm performs better than related protocols in terms of delivery rate and efficiency.
Reified Context Models

A classic tension exists between exact inference in a simple model and approximate inference in a complex model. The latter offers expressivity and thus accuracy, but the former provides coverage of the space, an important property for confidence estimation and learning with indirect supervision. In this work, we introduce a new approach, reified context models, to reconcile this tension. Specifically, we let the choice of factors in a graphical model (the contexts) be random variables inside the model itself. In this sense, the contexts are reified and can be chosen in a data-dependent way. Empirically, we show that our approach obtains expressivity and coverage on three sequence modeling tasks.
Reconceptualizing Church and State: A Theoretical and Empirical Analysis of the Impact of Separation of Religion and State on Democracy

This article argues that the relationship between democracy and the separation of religion and state needs to be reexamined. We argue that previous studies have misconceptualized the impact that a lack of church-state separation can have on democracy, or have taken a narrow focus by concentrating on specific cases. We use principal component analysis and a large-n data set covering 125 countries to show that the separation of religion and state should be conceptualized multi-dimensionally and that it should be considered a component of democracy. Our findings show that as separation of religion and state increases, the level of democracy also increases.
Short-term production scheduling of an automated manufacturing facility

We describe a new implementation of the Kimemia-Gershwin hierarchical policy for the real-time scheduling of flexible manufacturing systems. Major improvements result at all three levels of the policy. The algorithm simplification, resulting in substantial reductions of off-line and on-line computation time, is reported, as is the improvement in performance through the elimination of chattering. Simulation results based on a detailed model of a printed circuit card assembly facility are summarized.
Molecular Beam Epitaxy of Ultra-High-Quality AlGaAs/GaAs Heterostructures: Enabling Physics in Low-Dimensional Electronic Systems

Among very-low-disorder systems of condensed matter, the high-mobility two-dimensional electron gas (2DEG) confined in aluminum gallium arsenide (AlGaAs)–gallium arsenide (GaAs) heterostructures holds a privileged position as a platform for the discovery of new electronic states driven by strong Coulomb interactions. Molecular beam epitaxy (MBE), an ultra-high vacuum (UHV), thin-film deposition technique, produces the highest quality 2DEGs and has played a central role in a number of discoveries that have at their root the interplay of reduced dimensionality, strong electron-electron interactions, and disorder. This review attempts to describe the latest developments in heterostructure design, MBE technology, and the evolution of our understanding of disorder that result in improved material quality and facilitate discovery of new phenomena at ever finer energy scales.
On embedding machine-processable semantics into documents

Most Web and legacy paper-based documents are available in human comprehensible text form, not readily accessible to or understood by computer programs. Here, we investigate an approach to amalgamate XML technology with programming languages for representational purposes that can enhance traceability, thereby facilitating semiautomatic extraction and update. Specifically, we propose a modular technique to embed machine-processable semantics into a text document with tabular data via annotations, resulting sometimes in ill-formed XML fragments, and evaluate this technique vis a vis document querying, manipulation, and integration. The ultimate aim is to be able to author and extract human-readable and machine-comprehensible parts of a document hand in hand and keep them side by side.
Revision of specification automata under quantitative preferences

We study the problem of revising specifications with preferences for automata based control synthesis problems. In this class of revision problems, the user provides a numerical ranking of the desirability of the subgoals in their specifications. When the specification cannot be satisfied on the system, then our algorithms automatically revise the specification so that the least desirable user goals are removed from the specification. We propose two different versions of the revision problem with preferences. In the first version, the algorithm returns an exact solution while in the second version the algorithm is an approximation algorithm with non-constant approximation ratio. Finally, we demonstrate the scalability of our algorithms and we experimentally study the approximation ratio of the approximation algorithm on random problem instances.
Attitudes toward culture and approach to international advertising

This article describes how U.S. international advertising managers view cultural differences and how they relate to approaches to international advertising.