cssi/SciSciGPT-SciSciNet huggingface dataset:
Regulatory governance and sector performance : methodology and evaluation for Electricity distribution in Latin America

This paper contributes to the literature that explores the link between regulatory governance and sector performance. The paper develops an index of regulatory governance and estimates its impact on sector performance, showing that indeed regulation and its governance matter. The authors use two unique databases: (i) the World Bank Performance Database, which contains detailed annual data for 250 private and public electricity companies in Latin America and the Caribbean; and (ii) the Electricity Regulatory Governance Database, which contains data on several aspects of the governance of electricity agencies in the region. The authors run different models to explain the impacts of change in ownership and different characteristics of the regulatory agency on the performance of the utilities. The results suggest that the mere existence of a regulatory agency, regardless of the utilities' ownership, has a significant impact on performance. Furthermore, after controlling for the existence of a regulatory agency, the ownership dummies are still significant and with the expected signs. The authors propose an experience measure in order to identify the gradual impact of the regulatory agency on utility performance. The results confirm this hypothesis. In addition, the paper explores two different measures of governance, an aggregate measure of regulatory governance, and an index based on principal components, including autonomy, transparency, and accountability. The findings show that the governance of regulatory agencies matters and has significant effects on performance.
Music, Neuroscience, and the Psychology of Well-Being: A Précis

In Flourish, the positive psychologist Martin Seligman (2011) identifies five commonly recognized factors that are characteristic of human flourishing or wellbeing: (1) “positive emotion,” (2) “relationships,” (3) “engagement,” (4) “achievement,” and (5) “meaning” (p. 24). Although there is no settled set of necessary and sufficient conditions neatly circumscribing the bounds of human flourishing (Seligman, 2011), we would mostly likely consider a person that possessed high levels of these five factors as paradigmatic or prototypical of human flourishing. Accordingly, if we wanted to go about the practical task of actually increasing our level of wellbeing, we ought to do so by focusing on practically increasing the levels of the five factors that are characteristic of wellbeing. If, for instance, an activity such as musical engagement can be shown to positively influence each or all of these five factors, this would be compelling evidence that an activity such as musical engagement can positively contribute to one’s living a flourishing life. I’m of the belief that psychological research can and should be used, not only to identify and diagnose maladaptive psychological states, but identify and promote adaptive psychological states as well. In this article I advance the hypothesis and provide supporting evidence for the claim that musical engagement can positively contribute to one’s living a flourishing life. Since there has not yet been a substantive and up-to-date investigation of the possible role of music in contributing to one’s living a flourishing life, the purpose of this article is to conduct this investigation, thereby bridging the gap and stimulating discussion between the psychology of music and the psychology of wellbeing.
Work—nonwork conflict and the perceived quality of life

From additive models of overall quality of life, two hypotheses were derived about the relationships among work—family conflict, work—leisure conflict, job satisfaction, family satisfaction, leisure satisfaction and global life satisfaction. In supporting these two hypotheses, path analyses of survey data from a national probability sample of United States workers (n = 823) showed: (1) the direct paths between work—nonwork conflict and global life satisfaction were nonsignificant; and (2) the indirect paths between work—nonwork conflict and global life satisfaction, which are mediated by job satisfaction and nonwork satisfaction, were all significant. Further analyses indicated that, in general, the magnitude of these path coefficients was not significantly moderated by sociodemographic variables. Discussion considered the role of additive models as conceptual frameworks for studies concerned with the effects of work experiences on the overall quality of life.
U.S. High School Graduation Rates: Patterns and Explanations

Abstract I survey the evidence on patterns in U.S. high school graduation rates over the period 1970–2010 and report the results of new research conducted to fill in holes in the evidence. I begin by pointing out the strengths and limitations of existing data sources. I then describe six striking patterns in graduation rates. They include stagnation over the last three decades of the twentieth century, significant race-, income-, and gender-based gaps, and significant increases in graduation rates over the first decade of the twenty-first century, especially among blacks and Hispanics. I then describe the models economists use to explain the decisions of individuals to invest in schooling, and examine the extent to which the parameters of the models explain recent patterns in graduation rates. I find that increases in the nonmonetary costs of completing high school and the increasing availability of the GED credential help to explain stagnation in the face of substantial gaps between the wages of high sch...
Investigation of the Effect of Functional Group Substitutions on the Gas-Phase Electron Affinities and Ionization Energies of Room-Temperature Ionic Liquids Ions using Density Functional Theory

The cathodic and anodic stabilities of room-temperature ionic liquids (ILs) are important factors in their applications in electrochemical devices. In this work, we investigated the electron affinities of cations and ionization energies of anions for ionic liquids by density functional theory (DFT) calculations at the B3LYP/6-311+G(2d,p)//B3LYP/6-31+G(d) level. Over 200 unique cations and anions, formed from a set of six base cation structures, three base anion structures, and seven functional groups, were investigated. We find the trends in calculated EAs of alkylated cations and IEs of alkylated anions to be in good agreement with observed experimental trends in relative cathodic and anodic stabilities of various ILs. In addition, we also investigated the effect that functional group substitution at distinct positions in the ions have on the EA of the 1,2,3-trimethylimidazolium cation and the IE of the PF5CF3 anion. The overall impact on the EA or IE can be explained by the known electron-donating and electron-withdrawing inductive and resonance effects of the attached functional group, and the relative strength of the effect depends on the substitution position.
Phase separation in Cu47Ti33Zr11Ni8Si1

An atom probe tomography characterization of the microstructure of as-cast Cu 47 Ti 33 Zr 11 Ni 8 Si 1 that was either injection cast into a copper mold (cooling rate 4 × 10 3 K s -1 ) or splat quenched (cooling rate 2 x 10 6 K s -1 ) has been performed. In both materials, the bulk metallic glass had phase-separated into two interconnected amorphous phases. The copper-enriched regions were depleted in titanium and the copper-depleted regions were enriched in titanium. There was no difference in the degree of phase separation associated with the cooling rate.
Computational Algorithms for a Damage-coupled Cyclic Viscoplasticity Material Model:

The primary objective of this investigation is to develop efficient and robust computational schemes for a damage-coupled cyclic thermoviscoplasticity model for solder materials. Three constitutive integration algorithms, Euler, modified Euler, and semi-implicit algorithm for the model are examined. The three algorithms for the model are coded in the commercial finite element (FE) code ABAQUS (version 6.21) via its user-defined material subroutine UMAT. Two single-step algorithms of the substep scheme are applied for the modified Euler algorithm to control the error in the integration of constitutive laws. A semi-empirical formulation is established for an adaptive time stepping algorithm that is based on the Euler algorithm. The simulations of single-element, miniature specimen and notched specimen simulations have been conducted and compared with the test results under monotonic tensile, creep, and fatigue tests of 63Sn-37Pb solder. It is observed that the explicit algorithm consistently requires much l...
Multiple scattering in planetary atmospheres

Methods for solving radiative transfer problems within the extended visible spectrum in planetary atmospheres are reviewed for use by the nonspecialist. Emphasis is placed on rapid, approximate procedures for the determination of such quantities as the plane and spherical (Bond) albedo, surface illumination, absorbed energy, limb darkening, phase curve, and spectra. Precise numerical methods and analytical results are also discussed. Recent approaches to such complications as atmospheric inhomogeneity and reflection from a porous regolith are described briefly.
Virtual worlds in higher education: a policy simulation

The purpose of this paper is to explore whether virtual worlds can provide a setting for a rewarding learning experience for college students. The paper describes a policy-making simulation conducted within a virtual world and the results of an analysis conducted to assess its learning effectiveness. Our analysis, drawn from eight 'learning principles' advanced by Gee (2003), indicates that the levels of enthusiasm and learning that take place within a virtual world can differ considerably for different students: while some prefer traditional online methods, others are more enthusiastic about virtual world settings. Of the eight principles we considered, we found evidence to support 'identity and self knowledge', 'active learning', 'psychological moratorium' and 'content' principles. The 'affinity', 'transfer' and 'exploration' principles were not as well supported. In conclusion, we recommend that instructors give serious consideration to using virtual worlds as a tool to support interactive activities of students such as simulations.
Fitness-for-Service Assessment of Hydrocarbon Storage Tanks

Storage tanks are widely used in the industry to store hydrocarbon products. Corrosion damage is considered to be a serious threat to the structural integrity of the industrial storage tanks if it occurs on the primary pressure containment boundary. Therefore, fitness-for-service (FFS) assessment of these structures is performed periodically in order to ensure the operational safety and structural integrity. In this paper, evaluation methods are proposed for FFS assessment of storage tanks undergoing corrosion damage. The proposed methods are shown to give reasonably accurate and conservative assessment of the remaining strength factor. The methods are demonstrated through an example and the results are verified by inelastic finite element analysis.
Insertable Surgical Imaging Device with Pan, Tilt, Zoom, and Lighting

In this paper we describe work we have done in developing an insertable surgical imaging device with multiple degrees of freedom for minimally invasive surgery. The device is fully insertable into the abdomen using standard 12 mm trocars. It consists of a modular camera and lens system which has pan and tilt capability provided by two small DC servo motors. It also has its own integrated lighting system that is part of the camera assembly. Once the camera is inserted into the abdomen, the insertion port is available for additional tooling, motivating the idea of single-port surgery. A third zoom axis has been designed for the camera as well, allowing close-up and far-away imaging of surgical sites with a single camera unit. In animal tests with the device we have performed surgical procedures including cholecystectomy, appendectomy, running (measuring) the bowel, suturing, and nephrectomy. Preliminary tests suggest that the new device may have advantages over a standard laparoscope including the following. â¢ Low-cost and simple design. â¢ Easier and more intuitive to use than a standard laparoscope. â¢ Joystick operation requires no specialized operator training. â¢ Pan/tilt functions provide a large imaging volume not restricted by the fulcrum point of standard laparoscope. â¢ Time to perform procedures was better than or equivalent to a standard laparoscope. We believe these insertable platforms will be an integral part of future surgical systems. The platforms can be used with tooling as well as imaging devices, allowing many surgical procedures to be performed using such a system.
Comparison of energy spreads induced by a longitudinal wakefield in a cavity

It is pointed out that the energy spread of a beam bunch induced in a linear accelerator can be reduced to a minimum if the amplitude and the phase of the RF voltage are optimized. The energy spread is induced by the longitudinal wakefield and by the sinusoidal profile of the accelerating voltage acting on the beam. The cavity shape, the bunch profile, and the charge in the bunch determine the wake function. In order to have an approximately constant net voltage acting across the beam bunch, the amplitude and the phase of the RF voltage are optimized. The minimum energy spread, the required RF voltage, and the required RF phase are calculated as a function of the net charge and the length of the bunch. To determine the effect of cavity shape on the minimum energy spread, the optimization was performed for several types of cavities. The optimization shows that the energy spread can be reduced by a factor of 3 for the Energy Recovery Experiment (ERX)-type cavity and the Modular Component Technology Development (MCTD)-type cavity by adjusting the amplitude and the phase of the RF voltage. This is done by increasing RF voltage and phase. However, the ERX-type cavity is superior because it requires a third of the voltage of the MCTD to attain the same energy spread. >
Single Crystal X‐ray Structure Investigation and Electronic Structure Studies of La‐Deficient Nickel Stannide La4.87Ni12Sn24 Grown from Sn Flux

The cubic La4.87Ni12Sn24 was synthesized in reactions involving liquid Sn. The compound crystallizes in the cubic syngony, space group Im3¯, Z = 2, cell parameter a = 11.9662(14) A, and is related to the Gd3Ni8Sn16 structure type previously refined from powder X-ray data. The crystal structure of La4.87Ni12Sn24 was solved and refined using single crystal X-ray data to final R1 = 2.67%, wR2 = 6.92%. The refinement showed no mixed occupancy with Sn for the La(1) site, contrary to what was proposed for Gd3Ni8Sn16. Instead, a partial occupancy of 87% was detected for the La(1) at 2a. Electronic structure calculations show that the system is metallic, and the density of states at the Fermi level falls at a peak with the highest contribution coming from La(1) atoms, if the compound with ideal occupancies La5Ni12Sn24 is assumed. The deficiency of the La(1) site could therefore originate in the lowering of the total energy of the system due to the loss of 0.39 electrons per formula unit. Magnetic measurement data indicates nearly temperature independent Pauli paramagnetism. Theoretical estimation of the magnetic susceptibility after including core diamagnetic corrections agrees well with experiment. Einkristall-Rontgenstrukturanalyse und Untersuchungen zur Elektronenstruktur eines aus einer Zinnschmelze erhaltenen Nickelstannides mit La-Unterschus, La4.87Ni12Sn24 Kubisches La4, 87Ni12Sn24 wurde durch Reaktionen aus flussigem Zinn erhalten. Die Verbindung kristallisiert kubisch, Raumgruppe Im3¯, Z = 2, a = 11, 9662(14)A und ist mit dem Gd3Ni8Sn16-Strukturtyp verwandt, der fruher aus Rontgenpulverdaten verfeinert wurde. Die Kristallstruktur von La4, 87Ni12Sn24 wurde aus Einkristall-Rontgendaten bestimmt und bis zu R1 = 2, 67%, wR2 = 6, 92% verfeinert. Die Verfeinerung zeigte keine gemischte Besetzung von Sn und La auf La(1)-Platzen, im Gegensatz zu dem was fur Gd3Ni8Sn16 vorgeschlagen wurde. Statt dessen wird nur eine 87%ige Besetzung von La(1) auf der Lage 2a beobachtet. Rechnungen zurelektronischen Struktur zeigen, dass das System metallisch ist und die Zustandsdichte am Ferminiveau fallt mit dem grosten Beitrag durch La(1)-Atome zusammen, wenn fur die Verbindung die ideale Besetzung La5Ni12Sn24 angenommen wird. Die Unterbesetzung auf den La(1)-Platzen konnte deshalb mit der Erniedrigung der Gesamtenergie des Systems durch den Verlust von 0, 39 Elektronen pro Formeleinheit zusammen hangen.Magnetische Messungen zeigen einen nahezu temperaturunabhangigen Pauli-Paramagnetismus. Die theoretische Beurteilung der magnetischen Suszeptibilitat unter Beachtung der diamagnetischen Korrekturen stimmt gut mit dem Experiment uberein.
A Market for Time Fairness and Efficiency in Waiting Lines

SUMMARY In situations of excess demand, many firms use waiting lists to allocate products and services among their customers. The resulting allocation is likely to be inefficient, creating opportunities for Pareto improving trades among those who are waiting in line. Yet, in the queuing context, the trading of places is rare and inefficiencies often persist over time. In this paper, I report the results of a field experiment which allows randomly selected customers to earn up to $10 for letting a stranger cut in line. The higher the offer, the more likely it is that individuals let someone cut in. But while a majority agrees to wait longer, only a small minority accepts the monetary reward. Trading in this market is constrained by multiple social concerns. The obligation not to exploit situations of excess demand and efficiency considerations influence the willingness to let a stranger jump the queue.
Design and flight test of a lateral-directional command augmentationsystem

Two-input/two-output lateral-directional control laws with Type 0 and Type 1 structures have been designed, analyzed, and flight-tested using the microprocessor-based digital f light control system (Micro-DFCS) installed in Princeton's Variable-Respons e R esearch Aircraft (VRA). These control laws were designed u sing linear-quadratic sampled-data regulator theory, and they were evaluated by U.S. Navy test pilots. Major closed-loop response features were found to be relatively insensitive to sampling rate (down to 4 sps), although flying qualities were degraded b y increased sampling delay. Type 0 controllers provided satisfactory performance in flight, but the equivalent Type 1 systems were found to be unduly sensitive to dkpurbances and measurement noise. A novel application of the Tustin transformation proved useful in control law implementation.
Passive microwave observation of soil water infiltration

Infiltration is a time varying process of water entry into soil. Experiments were conducted using truck based microwave radiometers to observe small plots during and following sprinkler irrigation. Experiments were conducted on a sandy loam soil in 1994 and a silt loam in 1995. Sandy loam soils typically have higher infiltration capabilities than clays. For the sandy loam, the observed brightness temperature (TB) quickly reached a nominally constant value during irrigation. When the irrigation was stopped the TB began to increase as drainage took place. The irrigation rates in 1995 with the silt loam soil exceeded the saturated conductivity of the soil. During irrigation the TB values exhibited a pattern that suggests the occurrence of coherent reflection, a rarely observed phenomena under natural conditions. These results suggested the existence of a sharp dielectric boundary (wet over dry soil) that was increasing in depth with time.
Transverse energy evolution as a test of parton cascade models

Abstract We propose a test of Monte Carlo Parton Cascade models based on analytic solutions of covariant kinetic theory for longitudinally boost and transverse translation invariant boundary conditions. We compute the evolution of the transverse energy per unit rapidity for typical mini-jet initial conditions expected in ultra-relativistic nuclear collisions. The kinetic theory solutions under these conditions test the models severely because they deviate strongly from free-streaming and also from ideal Euler and dissipative Navier-Stokes hydrodynamical approximations. We show that the newly formulated ZPC model passes this test. In addition, we show that the initial mini-jet density would need to be approximately four times higher than estimated with the HIJING generator in central Au+Au collisions at c.m. energies 200 A GeV in order that parton cascade dynamics can be approximated by Navier-Stokes hydrodynamics.
An experimental evaluation and comparison of explicit force control strategies for robotic manipulators

The authors present results of experimental tests of a broad spectrum of basic force control strategies: proportional with feedforward, integral, filtered feedback proportional-derivative, and second-order low-pass filtering. The experiments were performed on the CMU Direct Drive Arm II so that the results would reflect the nature of the controller and not the unmodeled aspects of the system which comprises the plant. The commonality amongst the experiments was such that it was possible to compare and contrast the strategies objectively and to draw conclusions about the efficacy of each. The results support previous analysis and show the superiority of integral force control for force trajectory tracking. >
Business cycles in the euro area defined with coincident economic indicators and predicted with leading economic indicators

Clusters of cyclical turning points in the coincident indicators help us identify and date euro area recessions and recoveries in the past several decades. In the USA and some other countries, composite indexes of coincident indicators (CEI) are used to date classical business cycle turning points; also indexes of leading indicators (LEI) are used to help in the difficult task of predicting these turning points. This paper reviews a selection of the available data for monthly and quarterly euro area coincident and leading indicators. From these data, we develop composite indexes using methods analogous to those tested in the US CEI and LEI published by The Conference Board. We compare the resulting business cycle chronology with the existing alternatives and evaluate our selection of leading indicators in the context of how well they predict current economic activity and its major fluctuations for the euro area. Copyright © 2009 John Wiley & Sons, Ltd.
Random Sampling of States in Dynamic Programming

We combine three threads of research on approximate dynamic programming: sparse random sampling of states, value function and policy approximation using local models, and using local trajectory optimizers to globally optimize a policy and associated value function. Our focus is on finding steady-state policies for deterministic time-invariant discrete time control problems with continuous states and actions often found in robotics. In this paper, we describe our approach and provide initial results on several simulated robotics problems.
Tobin's Q and financial policy

Abstract Recent research in macroeconomics has emphasized the importance of linking the financial and real sectors and working with optimizing models. Tobin's Q model of investment would appear to provide a framework satisfying these two criteria. In contrast to the original presentation of the Q model, the formal development has not recognized that the firm actively participates in a number of financial markets; in this broader context, Q may be an uninformative and possibly misleading signal for investment expenditures. We then endeavor to turn this negative theoretical result to positive advantage in resolving a number of empirical problems with Q models.
Oxidative Cyclization Reactions: Controlling the Course of a Radical Cation‐Derived Reaction with the Use of a Second Nucleophile

The oxidative generation of reactive radical cation intermediates can serve as a powerful tool for the construction of new ring systems.[1,2] For example, substrates with electronrich olefins can be oxidized to generate radical cations that trigger cyclizations with a variety of electron-rich groups.[3] Enol ethers, vinylsulfides, ketene derivatives, electron-rich aryl rings, and styrenes have all been oxidized to form radical cations, whereas enol ethers, allyl and vinylsilanes, aryl rings, styrenes, alcohols, amides, sulfonamides, and amines have all been used to trap the radical cation. The reactions have led to the synthesis of fused and bicyclic ring skeletons and are often compatible with the formation of tetrasubstituted carbons. In addition, they have served to help us gain a better understanding of radical cation intermediates.[4]
A branch-and-bound algorithm for representative integer efficient solutions in multiple objective network programming problems

In many applications of multiple objective network programming (MONP) problems, only integer solutions are acceptable as the final optimal solution. Representative efficient solutions are usually obtained by sampling the efficient set through the solution of augmented weighted Tchebycheff network programs. Because such efficient solutions are usually not integer solutions, a branch-and-bound (BB) algorithm is developed to find integer efficient solutions. The purpose of the BB algorithm is to support interactive procedures by generating representative integer efficient solutions. To be computationally efficient, the algorithm takes advantage of the network structure as much as possible. An algorithm, used in the BB algorithm and performed on the key tree, is developed to construct feasible solutions from infeasible solutions and basic solutions from nonbasic solutions when bounds on branching variables change. The BB algorithm finds basic and nonbasic or supported and unsupported integer efficient solutions as long as they are optimal. Details of the algorithm are presented, an example is provided and computational results are reported. Computational results show that the BB algorithm performs well. Although the BB algorithm is developed for the purpose of generating integer efficient solutions for MONP problems, it can also solve more general integer network flow problems with linear side constraints. © 2013 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2013
Phonon gap and localization lengths in floppy materials

Gels of semi-flexible polymers, network glasses made of low valence elements, softly compressed ellipsoid particles and dense suspensions under flow are examples of floppy materials. These systems present collective motions with almost no restoring force. To study theoretically and numerically the frequency-dependence of the response of these materials and the length scales that characterize their elasticity, we use a model of isotropic floppy elastic networks. We show that such networks present a phonon gap for frequencies smaller than a frequency ω* governed by coordination, and that the elastic response is characterized, and in some cases localized, on a length scale that diverges as the phonon gap vanishes (with a logarithmic correction in the two dimensional case). lc also characterizes velocity correlations under shear, whereas another length scale l* ∼ 1/ω* controls the effect of pinning boundaries on elasticity. We discuss the implications of our findings for suspension flows, and the correspondence between floppy materials and amorphous solids near unjamming, where lc and l* have also been identified but where their roles are not fully understood.
Transmural flow bioreactor for vascular tissue engineering.

Nutrient transport limitation remains a fundamental issue for in vitro culture of engineered tissues. In this study, perfusion bioreactor configurations were investigated to provide uniform delivery of oxygen to media equivalents (MEs) being developed as the basis for tissue-engineered arteries. Bioreactor configurations were developed to evaluate oxygen delivery associated with complete transmural flow (through the wall of the ME), complete axial flow (through the lumen), and a combination of these flows. In addition, transport models of the different flow configurations were analyzed to determine the most uniform oxygen profile throughout the tissue, incorporating direct measurements of tissue hydraulic conductivity, cellular O2 consumption kinetics, and cell density along with ME physical dimensions. Model results indicate that dissolved oxygen (DO) uniformity is improved when a combination of transmural and axial flow is implemented; however, detrimental effects could occur due to lumenal pressure exceeding the burst pressure or damaging interstitial shear stress imparted by excessive transmural flow rates or decreasing hydraulic conductivity due to ME compaction. The model was verified by comparing predicted with measured outlet DO concentrations. Based on these results, the combination of a controlled transmural flow coupled with axial flow presents an attractive means to increase the transport of nutrients to cells within the cultured tissue to improve growth (increased cell and extracellular matrix concentrations) as well as uniformity. Biotechnol. Bioeng. 2009; 104: 1197–1206. © 2009 Wiley Periodicals, Inc.
Chemical Timescales in the Atmospheres of Highly Eccentric Exoplanets

Close-in exoplanets with highly eccentric orbits are subject to large variations in incoming stellar flux between periapse and apoapse. These variations may lead to large swings in atmospheric temperature, which in turn may cause changes in the chemistry of the atmosphere from higher CO abundances at periapse to higher CH{sub 4} abundances at apoapse. Here, we examine chemical timescales for CO{r_reversible}CH{sub 4} interconversion compared to orbital timescales and vertical mixing timescales for the highly eccentric exoplanets HAT-P-2b and CoRoT-10b. As exoplanet atmospheres cool, the chemical timescales for CO{r_reversible}CH{sub 4} tend to exceed orbital and/or vertical mixing timescales, leading to quenching. The relative roles of orbit-induced thermal quenching and vertical quenching depend upon mixing timescales relative to orbital timescales. For both HAT-P-2b and CoRoT-10b, vertical quenching will determine disequilibrium CO{r_reversible}CH{sub 4} chemistry at faster vertical mixing rates (K{sub zz} > 10{sup 7} cm{sup 2} s{sup -1}), whereas orbit-induced thermal quenching may play a significant role at slower mixing rates (K{sub zz} < 10{sup 7} cm{sup 2} s{sup -1}). The general abundance and chemical timescale results-calculated as a function of pressure, temperature, and metallicity-can be applied for different atmospheric profiles in order to estimate the quench level and disequilibrium abundances of COmore » and CH{sub 4} on hydrogen-dominated exoplanets. Observations of CO and CH{sub 4} on highly eccentric exoplanets may yield important clues to the chemical and dynamical properties of their atmospheres.« less
Enantioselective desymmetrization of meso-aziridines with TMSN3 or TMSCN catalyzed by discrete yttrium complexes.

using a variety ofnucleophiles have been the subject of extensive research. Theless developed ring-opening reactions, those of meso-aziri-dines by carbon and nitrogen nucleophiles, give direct accessto enantiopure b-amino acids and 1,2-diamines—two classesof compounds which have broad chemical and pharmaceut-ical relevance. Li, Fernndez, and Jacobsen first reportedenantioselective ring-opening of meso-aziridines withTMSN
The observed infrared properties of grains in space

The infrared properties of dust in space, as inferred from infrared observations at low to moderate spectral resolution at wavelengths ≲30 μm are summarized. Condensates at high temperature: featureless material and silicon carbide; moderate temperature: silicates; and low temperature — ices are briefly discussed. Strong band emission from as yet unknown species has been detected in a variety of objects. Episodes of rapid dust formation have been recorded in the infrared spectra of certain eruptive variable stars, including classical novae. Observations of this class of objects promises to provide information on grain nucleation and growth.
Distributed Authentication of Program Integrity Verification in Wireless Sensor Networks

Security in wireless sensor networks has become important as they are being developed and deployed for an increasing number of applications. The severe resource constraints in each sensor make it very challenging to secure sensor networks. Moreover, sensors are usually deployed in hostile and unattended environments and hence are susceptible to various attacks, including node capture, physical tampering, and manipulation of the sensor program. Park and Shin [2005] proposed a soft tamper-proofing scheme that verifies the integrity of the program in each sensor device, called the program integrity verification (PIV), in which sensors authenticate PIV servers (PIVSs) using centralized and trusted third-party entities, such as authentication servers (ASs). This article presents a distributed authentication protocol of PIVSs (DAPP) without requiring the commonly used ASs. DAPP uses the Blundo scheme [Blundo et al. 1992] for sensors and PIVSs to establish pairwise keys and for PIVSs to authenticate one another. We also present a protocol for PIVSs to cooperatively detect and revoke malicious PIVSs in the network. We implement and evaluate both DAPP and PIV on Mica2 Motes and laptops, showing that DAPP reduces the sensors' communication traffic in the network by more than 90p and the energy consumption on each sensor by up to 85p, as compared to the case of using a centralized AS for authenticating PIVSs. We also analyze the security of DAPP under various attack models, demonstrating its capability in dealing with diverse types of attacks.
ResourceSync: leveraging sitemaps for resource synchronization

Many applications need up-to-date copies of collections of changing Web resources. Such synchronization is currently achieved using ad-hoc or proprietary solutions. We propose ResourceSync, a general Web resource synchronization protocol that leverages XML Sitemaps. It provides a set of capabilities that can be combined in a modular manner to meet local or community requirements. We report on work to implement this protocol for arXiv.org and also provide an experimental prototype for the English Wikipedia as well as a client API.
Relative sliding durability of two candidate high temperature oxide fiber seal materials

A test program to determine the relative sliding durability of two candidate ceramic fibers for high temperature sliding seal applications is described. Pin on disk tests were used to evaluate potential seal materials. Friction during the tests and fiber wear, indicated by the extent of fibers broken in a test bundle or yarn, was measured at the end of a test. In general, friction and wear increase with test temperature. This may be due to a reduction in fiber strength, a change in the surface chemistry at the fiber/counterface interface due to oxidation, adsorption and/or desorption of surface species and, to a lesser extent, an increase in counterface surface roughness due to oxidation at elevated temperatures. The relative fiber durability correlates with tensile strength indicating that tensile data, which is more readily available than sliding durability data, may be useful in predicting fiber wear behavior under various conditions. A simple model developed using dimensional analysis shows that the fiber durability is related to a dimensionless parameter which represents the ratio of the fiber strength to the fiber stresses imposed by sliding.
Energy-efficient design of battery-powered embedded systems

Energy-efficient design of battery-powered systems demands optimizations in both hardware and software. We present a modular approach for enhancing instruction level simulators with cycle-accurate simulation of energy dissipation in embedded systems. Our methodology has tightly coupled component models thus making our approach more accurate. Performance and energy computed by our simulator are within a 5% tolerance of hardware measurements on the SmartBadge. We show how the simulation methodology can be used for hardware design exploration aimed at enhancing the SmartBadge with real-time MPEG video feature. In addition, we present a profiler that relates energy consumption to the source code. Using the profiler we can quickly and easily redesign the MP3 audio decoder software to run in real time on the SmartBadge with low energy consumption. Performance increase of 92% and energy consumption decrease of 77% over the original executable specification have been achieved.
Market-Based Allocation with Indivisible Bids

We study multiunit double auctions accepting bids with indivisibility constraints. Modeling the auction problem as a Multiple Choice Knapsack Problem and using dynamic programming, we show that incremental computations during bid processing can speed the handling of key auction operations such as clearing and quoting. We propose different price-quote policies and study their influence on the efficiency of market-based allocation. Using a reconfigurable manufacturing scenario where agents trade large quantities of multiple goods, we demonstrate potential benefits of supporting indivisibility constraints in bidding. These benefits are highly sensitive to the form of price quote provided, indicating interesting tradeoffs in communication and allocation efficiency.
THz Dynamic Nuclear Polarization NMR

Dynamic nuclear polarization (DNP) increases the sensitivity of nuclear magnetic resonance (NMR) spectroscopy by using high frequency microwaves to transfer the polarization of the electrons to the nuclear spins. The enhancement in NMR sensitivity can amount to a factor of well above 100, enabling faster data acquisition and greatly improved NMR measurements. With the increasing magnetic fields (up to 23 T) used in NMR research, the required frequency for DNP falls into the THz band (140- 600 GHz ). Gyrotrons have been developed to meet the demanding specifications for DNP NMR, including power levels of tens of watts; frequency stability of a few megahertz; and power stability of 1% over runs that last for several days to weeks. Continuous gyrotron frequency tuning of over 1 GHz has also been demonstrated. The complete DNP NMR system must include a low loss transmission line; an optimized antenna; and a holder for efficient coupling of the THz radiation to the sample. This paper describes the DNP NMR process and illustrates the THz systems needed for this demanding spectroscopic application. THz DNP NMR is a rapidly developing, exciting area of THz science and technology.
The (4+3)-cycloaddition reaction: heteroatom-substituted allylic cations as dienophiles

The (4+3)-cycloaddition of allylic cations to dienes is a powerful method for the direct synthesis of seven-membered rings. Recent developments in this area have included new methods for the generation of allylic cations, diastereoselective and catalytic, enantioselective reactions, an increased understanding of the diverse mechanistic possibilities of the reaction and applications to the total synthesis of natural products and their analogues.
New Developments in Econometric Methods for Labor Market Analysis

Abstract Econometric practice in labor economics has changed over the past 10 years as probit, logit, hazard methods, instrumental variables, and fixed effects models have grown in use and selection bias methods have declined in use. To a large degree these trends reflect an increasing preference for methods which are less restrictive, more robust, and freer in functional form than older methods, although not all trends are consistent with this view. The trends also reflect a tension between structural and reduced-form estimation that has not yet been resolved. A major point of the review is that this trend in labor economic practice has paralleled a trend in econometrics involving the use of flexible forms and semi-parametric and non-parametric methods but has not incorporated the lessons from that field. © 1999 Elsevier Science B.V. All rights reserved.
Codes, automata, and continuous systems: Explicit interconnections

Close relationships are established between convolutional codes and zero-state automata and between cyclic codes and zero-input automata. Furthermore, techniques of automata theory and continuous system theory are used to elaborate on the coding problem; and approaches from coding and automata are used to establish and interpret typical structural conditions in continuous systems. The investigation incorporates basic coding concepts into the currently emerging common basis for automata and continuous systems, and it gives explicit examples of the resulting benefits accruing to each of these areas from the others.
Prevalence of venous thromboembolism in patients with secondary polycythemia

To investigate an association between secondary polycythemia and venous thromboembolism (VTE) risk, we performed a case-control study to compare the prevalence of VTE in participants with secondary polycythemia due to chronic obstructive pulmonary disease (COPD; N = 86) to that in age- and sex-matched controls with COPD without secondary polycythemia (N = 86). Although there was a significant difference in mean hematocrit between cases and controls (53.5% vs 43.6%, respectively; P < .005), we identified no difference in the number of total or idiopathic VTE events in the 2 groups. Patients with VTE, however, had a significantly higher body mass index than patients without VTE. Our findings suggest that secondary polycythemia alone may not be a significant risk factor for VTE but that VTE risk in this population may be related to known risk factors such as obesity. The role of phlebotomy for VTE risk reduction secondary polycythemia is therefore questionable.
Quantal Andreev billiards: Semiclassical approach to mesoscale oscillations in the density of states

Andreev billiards are finite, arbitrarily-shaped, normal-state regions, surrounded by superconductor. At energies below the superconducting gap, single-quasiparticle excitations are confined to the normal region and its vicinity, the essential mechanism for this confinement being Andreev reflection. This Paper develops and implements a theoretical framework for the investigation of the short-wave quantal properties of these single-quasiparticle excitations. The focus is primarily on the relationship between the quasiparticle energy eigenvalue spectrum and the geometrical shape of the normal-state region, i.e., the question of spectral geometry in the novel setting of excitations confined by a superconducting pair-potential. Among the central results of this investigation are two semiclassical trace formulas for the density of states. The first, a lower-resolution formula, corresponds to the well-known quasiclassical approximation, conventionally invoked in settings involving superconductivity. The second, a higher-resolution formula, allows the density of states to be expressed in terms of: (i) An explicit formula for the level density, valid in the short-wave limit, for billiards of arbitrary shape and dimensionality. This level density depends on the billiard shape only through the set of stationary-length chords of the billiard and the curvature of the boundary at the endpoints of these chords; and (ii) Higher-resolution corrections to the level density, expressed as a sum over periodic orbits that creep around the billiard boundary. Owing to the fact that these creeping orbits are much longer than the stationary chords, one can, inter alia, hear the stationary chords of Andreev billiards.
Price Stickiness: Empirical Evidence of the Menu Cost Channel

Abstract A leading explanation in the economic literature is that monetary policy has real effects on the economy because firms incur a cost when changing prices. Using a unique database of cost and retail price changes, we find that variation in menu costs results in up to 13.3% fewer price increases. We confirm that these effects are allocative and have a persistent impact on both prices and unit sales. We provide evidence that the menu cost channel operates only when cost increases are small in magnitude, which is consistent with theory and provides the first empirical evidence of boundary conditions.
Anorthite - Thermal equation of state to high pressures

The shock wave (Hugoniot) data on single crystal and porous anorthite (CaAl2Si208) to pressures of 120 GPa are presented. These data are inverted to yield high pressure values of the Grueneisen parameter, adiabatic bulk modulus, and coefficient of thermal expansion over a broad range of pressures and temperatures which in turn are used to reduce the raw Hugoniot data and construct an experimentally based, high pressure thermal equation of state for anorthite. The hypothesis that higher order anharmonic contributions to the thermal properties decrease more rapidly upon compression than the lowest order anharmonicities is supported. The properties of anorthite corrected to lower mantle conditions show that although the density of anorthite is comparable to that of the lower most mantle, its bulk modulus is considerably less, hence making enrichment in the mantle implausible except perhaps near its base.
AN IMPLICIT COVER PROBLEM IN WILD POPULATION STUDY

In an implicit combinatorial optimization problem, the constraints are not enumerated explicitly but rather stated implicitly through equations, other constraints or auxiliary algorithms. An important subclass of such problems is the implicit set cover (or, equivalently, hitting set) problem in which the sets are not given explicitly but rather defined implicitly. For example, the well-known minimum feedback arc set problem is such a problem. In this paper, we consider such a cover problem that arises in the study of wild populations in biology in which the sets are defined implicitly via the Mendelian constraints and prove approximability results for this problem.
Water-soluble pH-sensitive 2,6-bis(substituted ethylidene)-cyclohexanone/hydroxy cyanine dyes that absorb in the visible/near-infrared regions

Three methods were used to synthesize a series of the title compounds. The ketones absorb in the visible region, and upon protonation (pH 700 nm). The conversion is reversible and depends solely on pH conditions.
Nexus Work: Brokerage on Creative Projects:

This study examined how brokers on creative projects integrate the ideas of others. We use the term “nexus work” to refer to brokerage requiring synthesis or integration, rather than just communication or transference of ideas. With an ethnographic investigation of 23 independent music producers in the Nashville country music industry, we examined how producers in the brokerage role fostered the integration of others' contributions throughout four phases of the creative process. We discovered that ambiguity was an inherent part of the collective creative process and identified three types: (1) an ambiguous quality metric (What makes a hit or constitutes success?); (2) ambiguous occupational jurisdictions (Whose claim of expertise entitles them to control the process?); and (3) an ambiguous transformation process (How should the work be done?). We show when each type of ambiguity became acute in the creative process and identify the practices producers used to leverage their brokerage role depending on the...