cssi/SciSciGPT-SciSciNet huggingface dataset:
Optical properties of solid particle receiver materials: II. Diffuse reflectance of Norton Masterbeads® at elevated temperatures

Abstract An experimental system to measure the diffuse reflectance of a particulate sample over the wavelength range of 300 to 2500 nm at elevated temperatures up to 1000°C has been developed and implemented. A description of the experimental apparatus and measurement procedures, as well as optical reflectance data for the Masterbeads ® , are presented. Using the high temperature measurement system, the diffuse reflectance of Masterbeads ® changed by less than 1% for sample temperatures from 150°C to 930°C. However, after heating a sample for three hours at 1000°C in air, the solar absorptance measured at room temperature decreased from an initial value of 0.93 to 0.89.
On the Two-Phase Structure of Protogalactic Clouds*

In the gaseous envelope of protogalaxies, thermal instability leads to the formation of a population of cool fragments that are confined by the pressure of a residual hot background medium. In order to remain in a quasi-hydrostatic equilibrium, the residual gas evolves at approximately the virial temperature of the dark matter halo. Its density is determined by the requirements of thermal equilibrium. The hot gas is heated by compression and shock dissipation. The heating is balanced by direct energy loss due to bremsstrahlung emission and by conductive losses into the cool clouds, which are efficient radiators. The cool fragments are photoionized and heated by the extragalactic UV background and nearby massive stars. Several processes interact to determine the size distribution of the cool fragments. The smallest are evaporated due to conductive heat transfer from the hot gas. All fragments are subject to disruption due to hydrodynamic instabilities. The fragments also gain mass as a result of collisions and mergers and of condensation from the hot gas due to conduction. The size distribution of the fragments in turn determines the rate and efficiency of star formation during the early phase of galactic evolution. We have performed one-dimensional hydrodynamic simulations of the evolution of the hot and cool gas. The cool clouds are assumed to follow a power-law size distribution, and fall into the galactic potential, subject to drag from the hot gas. The relative amounts of the hot and cool gas are determined by the processes discussed above, and star formation occurs at a rate sufficient to maintain the cool clouds at 104 K. We present density distributions for the two phases and also for the stars for several cases, parameterized by the circular speeds of the potentials. Under some conditions, primarily low densities of the hot gas, conduction is more efficient than radiative processes at cooling the hot gas, limiting the X-ray radiation from the halo gas.
India and China: Contrasts in economic liberalization?

Abstract It is argued that in both India and China despite some important differences: 1. (a) similar cultural and political imperatives led to similar systems of dirigisme and economic outcomes — with the Chinese growth higher than the Indian because of higher investment; 2. (b) crises engendered by their dirigiste regimes impelled reform; 3. (c) their attempts to replace the plan by the market have striking similarities but 4. (d) ultimately because of continuing atavistic attitudes to toward trade and commerce the reforms remain insecure.
Three-dimensional elliptic grid generation with fully automatic boundary constraints

A new procedure for generating smooth uniformly clustered three-dimensional structured elliptic grids is presented here which formulates three-dimensional boundary constraints by extending the two-dimensional counterpart presented by the author earlier. This fully automatic procedure obviates the need for manual specification of decay parameters over the six bounding surfaces of a given volume grid. The procedure has been demonstrated here for the Mars Science Laboratory (MSL) geometries such as aeroshell and canopy, as well as the Inflatable Aerodynamic Decelerator (IAD) geometry and a 3D analytically defined geometry. The new procedure also enables generation of single-block grids for such geometries because the automatic boundary constraints permit the decay parameters to evolve as part of the solution to the elliptic grid system of equations. These decay parameters are no longer just constants, as specified in the conventional approach, but functions of generalized coordinate variables over a given bounding surface. Since these decay functions vary over a given boundary, orthogonal grids around any arbitrary simply-connected boundary can be clustered automatically without having to break up the boundaries and the corresponding interior or exterior domains into various blocks for grid generation. The new boundary constraints are not limited to the simply-connected regions only, but can also be formulated around multiply-connected and isolated regions in the interior. The proposed method is superior to other methods of grid generation such as algebraic and hyperbolic techniques in that the grids obtained here are C^2 continuous, whereas simple elliptic smoothing of algebraic or hyperbolic grids to enforce C^2 continuity destroys the grid clustering near the boundaries.
Residue formulas for the large k asymptotics of Witten's invariants of Seifert manifolds. The case of SU(2)

We derive the largek asymptotics of the surgery formula forSU(2) Witten's invariants of general Seifert manifolds. The contributions of connected components of the moduli space of flat connections are identified. The contributions of irreducible connections are presented in the residue form. This allows us to express them in terms of intersection numbers on their moduli spaces.
Implementation of the lanczos method for structural vibration analysis on a parallel computer

The use of the Lanczos method in a parallel environment is investigated by implementing the algorithm for structural vibration problems on a parallel computer. It is shown that introducing shifts, assigning each processor a different region in the eigenvalue spectrum, and implementing the Lanczos method in parallel is an effective strategy for speeding up calculations. Test problem results include examples of the 'Lanczos phenomenon' where roundoff error in the vector orthogonalization can result in spurious eigenvalues which must be identified and discarded. The calculation strategy described here permits straightforward determination of these spurious eigenvalues. It is demonstrated that significant speedups in calculation time can be realized over traditional sequential methods.
Do Financial and Institutional Variables Enhance the Impact of Remittances on Economic Growth in Latin America and the Caribbean? A Panel Cointegration Analysis

Using recently developed panel unit root and panel cointegration tests and the Fully-Modified OLS methodology (FMOLS), this paper estimates the impact of remittances on the economic growth of selected upper and lower income Latin American & Caribbean (LAC) countries over the 1990–2007 period. Despite the large flow of remittances to the region, there have been relatively few empirical studies assessing the impact of remittances on economic growth in LAC. Panel unit root tests suggest that several of the macro variables included in the model exhibit unit roots, yet, at the same time, Pedroni’s panel cointegration test determined that there is a cointegrating relationship among the variables in the estimated model. The FMOLS estimates suggest that remittances have a positive and significant effect on economic growth in both groups of countries. The estimates also indicate that both the degree of economic freedom and credit provided by the banking system have a positive and significant effect on economic growth in upper (middle) income LAC countries. The sign of the interaction term between remittances and the credit (and EFI) variables suggest that remittances act as substitutes for these variables. Finally, the effect of remittances on both sets of countries is stronger in the presence of a financial (credit) variable.
Multiplicativity properties of entrywise positive maps

Abstract Multiplicativity of certain maximal p → q norms of a tensor product of linear maps on matrix algebras is proved in situations in which the condition of complete positivity (CP) is either augmented by, or replaced by, the requirement that the entries of a matrix representative of the map are non-negative (EP). In particular, for integer t, multiplicativity holds for the maximal 2 → 2t norm of a product of two maps, whenever one of the pair is EP; for the maximal 1 → t norm for pairs of CP maps when one of them is also EP; and for the maximal 1 → 2t norm for the product of an EP and a 2-positive map. Similar results are shown in the infinite-dimensional setting of convolution operators on L 2 ( R ) , with the pointwise positivity of an integral kernel replacing entrywise positivity of a matrix. These results apply in particular to Gaussian bosonic channels.
Multi-user MIMO scheduling in the fourth generation cellular uplink

In this paper, we consider Multi-User MIMO (MU-MIMO) scheduling in the 3GPP LTE-Advanced (3GPP LTE-A) cellular uplink. The 3GPP LTE-A cellular uplink allows for precoded multi-stream (precoded MIMO) transmission from each user scheduled in the uplink along with flexible multi-user scheduling, wherein multiple users can be assigned the same time-frequency resource. However, optimally exploiting these features is challenging since certain practical constraints have to be satisfied, such as the one which demands that the number of users co-scheduled on any time-frequency resource must not exceed a specified number. We show that while the resulting resource allocation problem is NP-hard, it can be formulated as the maximization of a non-negative monotonic submodular set function subject to one matroid and multiple column-sparse knapsack constraints. We then provide low complexity approximation algorithms and demonstrate their superior performance via simulations.
THE LOS ALAMOS PHOTOINJECTOR PROGRAM

Abstract Free electron lasers (FELs) require electron beams of high peak brightness. In this presentation, we describe the design of a compact high-brightness electron source for driving short-wavelength FELs. The experiment uses a laser-illuminated Cs 3 Sb photoemitter located in the first rf cavity of an injector linac. The photocathode source and associated hardware are described. The doubled YAG laser (532 nm), which is used to drive the photocathode, produces 75 ps micropulses at 108 MHz repetition rate and peak powers of approximately 300 kW. Diagnostics include a pepper-pot emittance analyzer, a magnetic spectrometer, and a 4 ps resolution streak camera. Present experiments give the following results: micropulse current amplitudes of 100 mA to 400 A, beam emittances ranging from 10 π mm mrad to 40 π mm mrad, an energy spread of ± 3%, and peak current densities of 600 A/cm 2 The design of experiment has now been changed to include a separately phased rf cavity immediately following the first cavity. This modification enables us to study the effects of phasing with the possibility of improving the injector performance. Also, this change will improve the vacuum conditions in the photoelectron source with a consequent improvement in lifetime performance. A brief discussion on the possible applications of this very bright and compact electron source is presented.
A bilinear oscillatory integral along parabolas

We establish an $$L^\infty \times L^2 \rightarrow L^2$$ norm estimate for a bilinear oscillatory integral operator along parabolas incorporating oscillatory factors $$e^{i|t|^{-\beta}}$$ .
The VEGF receptor flt-1 (VEGFR-1) is a positive modulator of vascular sprout formation and branching morphogenesis

Sprouting angiogenesis is critical to blood vessel formation, but the cellular and molecular controls of this process are poorly understood. We used time-lapse imaging of green fluorescent protein (GFP)-expressing vessels derived from stem cells to analyze dynamic aspects of vascular sprout formation and to determine how the vascular endothelial growth factor (VEGF) receptor flt-1 affects sprouting. Surprisingly, loss of flt-1 led to decreased sprout formation and migration, which resulted in reduced vascular branching. This phenotype was also seen in vivo, as flt-1 -/- embryos had defective sprouting from the dorsal aorta. We previously showed that loss of flt-1 increases the rate of endothelial cell division. However, the timing of division versus morphogenetic effects suggested that these phenotypes were not causally linked, and in fact mitoses were prevalent in the sprout field of both wild-type and flt-1 -/- mutant vessels. Rather, rescue of the branching defect by a soluble flt-1 (sflt-1) transgene supports a model whereby flt-1 normally positively regulates sprout formation by production of sflt-1, a soluble form of the receptor that antagonizes VEGF signaling. Thus precise levels of bioactive VEGF-A and perhaps spatial localization of the VEGF signal are likely modulated by flt-1 to ensure proper sprout formation during blood vessel formation. (Blood. 2004;103:4527-4535)
Towards a 4/3 approximation for the asymmetric traveling salesman problem

A long-standing conjecture in combinatorial optimization says that the integrality gap of the famous Held-Karp relaxation of the symmetric TSP is precisely 4/3. In this paper, we show that a slight strengthening of this conjecture implies a tight 4/3 integrality gap for a linear programming relaxation of the asymmetric TSP. This is surprising since no constant-factor approximation is known for the latter problem. Our main tools are a new characterization of the integrality gap for linear objective functions over polyhedra, and the isolation of ''hard-to-round'' solutions of the relaxations.
CEP populations observed by ISEE 1

[1] Observations on October 30, 1978 show the ISEE 1 spacecraft passing though the high-altitude dayside northern cusp region from roughly 16:00 to 18:30 UT, during a slow solar wind period (∼380 km/s). More than two orders of magnitude enhancements of the cusp energetic particle (CEP) fluxes are observed along with a depressed and turbulent local magnetic field and both ionospheric and solar wind plasma. The clock angle of the local magnetic field is different from that of the IMF, implying that the spacecraft was indeed inside the magnetosphere. The observed variations of the pitch angle distributions provide a unique opportunity to determine the structure of the cusp. The CEP fluxes were measured at about 8.5 hours MLT when the IMF had both an 8–10 nT duskward and southward component. The dawnside location of the cusp under these IMF conditions is unexpected by the existing models. No obvious time-energy dispersion is measured for the CEP fluxes. The time evolution of the phase space density as the spacecraft crossed the cusp boundary layer exhibits a positive gradient pointed to the high-altitude cusp, indicating a probable cusp source of the energetic particles. Through a careful analysis of the data available, we report the first detailed study of the equatorial orbiting ISEE 1 spacecraft passing through the high altitude cusp region.
Solar electric low-thrust missions to Jupiter with swingby continuation to the outer planets.

Solar electric low thrust propulsion application to Jupiter swingby mission to outer planets
Is Governance Reform a Catalyst for Development

International development agencies contend developing countries can boost rates of economic growth by introducing “good governance” measures. However, close analysis of specific governance reforms and economic turning points in the United States (when it was a developing country), Argentina, Mauritius, and Jamaica suggests that the agencies underestimate the time and political effort required to change governance, and overestimate the economic impact. Counter to optimistic claims about how much “institutions matter,” these carefully selected cases imply that greater transparency, accountability, and participation are often a result, rather than a direct cause of faster development. Furthermore, they show that closed institutions may be a satisfactory platform for rapid growth, provided those institutions open over time. Policymakers need to understand these processes better before counting on governance reforms to be the springboard out of poverty for most developing countries today.
Cationic cyclization reactions initiated by stabilized benzyl cations

Abstract The in situ generation of stabilized benzyl cations and their subsequent use in cyclization reactions with a monosubstituted benzene, a furan and a β-keto ester terminators is described.
Ego-centric Network Sampling in Viral Marketing Applications

Marketing is most successful when people spread the message within their social network. The Internet can serve as an approximation of the spread of messages, particularly marketing campaigns, to both measure marketing effectiveness and provide data for influencing future efforts. However, to measure the network of web sites spreading the marketing message potentially requires a massive amount of data collection over a long period of time. Additionally, collecting data from the Internet is very noisy and can create a false sense of precision. Therefore, we propose to use ego-centric network sampling to both reduce the amount of data required to collect as well as handle the inherent uncertainty of the data collected. In this paper, we study whether the proposed ego-centric network sampling accurately captures the network structure. We use the Stanford-Berkeley network to show that the approach can capture the underlying structure with a minimal amount of data.
Enantioselective synthesis of anti- and syn-β-hydroxy-α-phenyl carboxylates via boron-mediated asymmetric aldol reaction.

A reagent-controlled, diastereo- and enantioselective synthesis of anti- and syn-β-hydroxy-α-phenyl carboxylates has been achieved by the proper choice of solvent, temperature, alkoxy group, and amine for the diisopinocampheylboron-mediated asymmetric enolization–aldolization of phenylacetates. The pure diastereomers can be readily separated by column chromatography.
Applications of N‐Sulfinyl Dienophile Diels‐Alder Cycloadditions to Synthesis of Unusual Amino Sugars

The amino sugar moieties of staurosporine and nogalarol have been stereospecifically synthesized by a strategy utilizing N-sulfinyl Diels-Alder chemistry.
Parametric representations of general Green’s functions

Parametric representations for the Green’s function of field theory are derived in perturbation theory. These representations are valid for each term in the perturbation series that corresponds to a Feynman diagram, and reflect its analytic property and threshold characteristics. As an example, the three-body (vertex) function is shown to satisfy a dispersion relation when two of the three momenta are fixed, with the correct location of the singularities expected from the thresholds of the competing real processes.
Knowledge Compilation Meets Database Theory: Compiling Queries to Decision Diagrams

The goal of Knowledge Compilation is to represent a Boolean expression in a format in which it can answer a range of "online-queries" in PTIME. The online-query of main interest to us is model counting, because of its application to query evaluation on probabilistic databases, but other online-queries can be supported as well such as testing for equivalence, testing for implication, etc. In this paper we study the following problem: given a database query q, decide whether its lineage can be compiled efficiently into a given target language. We consider four target languages, of strictly increasing expressive power (when the size of compilation is restricted to be polynomial in the data size): read-once Boolean formulae, OBDD, FBDD and d-DNNF. For each target, we study the class of database queries that admit polynomial size representation: these queries can also be evaluated in PTIME over probabilistic databases. When queries are restricted to conjunctive queries without self-joins, it was known that these four classes collapse to the class of hierarchical queries, which is also the class of PTIME queries over probabilistic databases. Our main result in this paper is that, in the case of Unions of Conjunctive Queries (UCQ), these classes form a strict hierarchy. Thus, unlike conjunctive queries without self-joins, the expressive power of UCQ differs considerably with respect to these target compilation languages. Moreover, we give a complete characterization of the first two target languages, based on the query's syntax.
Top-Down modulation of neural responses in visual perception: a computational exploration

Visual perception is typically performed in the context of a task or goal. Nonetheless, visual processing has traditionally been conceptualized in terms of a fixed, task-independent hierarchy of feature detectors. We explore the computational implications of allowing early visual processing to be task modulated. Using artificial neural networks, we show that significant improvements in task accuracy can be obtained by allowing the weights to be modulated by task. The primary benefits are obtained under resource-limited processing. A relatively modest task-based modulation of weights and activities can lead to a large performance boost, suggesting an efficient means of increasing effective cortical capacity.
Spectral formation in compact X-ray sources

A method is described for calculating the transfer of X-rays through gas that is optically thick to Compton scattering. The method permits the simultaneous solution of the radiation-dominated temperature and ionization structure of the medium as well as the effects of incoherent Compton scattering of photons. Self-consistent results are obtained for idealized models of compact X-ray sources, represented as point sources of continuum X-rays surrounded by spherical shells of gas, demonstrating the range of spectral features that might result from such optically thick transfer. Some implications for the analysis of X-ray spectra of galactic X-ray sources are discussed.
Value-added modeling: A review

Abstract This article reviews the literature on teacher value-added. Although value-added models have been used to measure the contributions of numerous inputs to educational production, their application toward identifying the contributions of individual teachers has been particularly contentious. Our review covers articles on topics ranging from technical aspects of model design to the role that value-added can play in informing teacher evaluations in practice, highlighting areas of consensus and disagreement in the literature. Although a broad spectrum of views is reflected in available research, along a number of important dimensions the literature is converging on a widely-accepted set of facts.
A double time-of-flight (E−ΔE) mass spectrometer

Abstract A correlated (E−ΔE) double time-of-flight mass spectrometer was designed and used in the d E d x measurements of 235U fission fragments in nickel as a function of mass and energy. The system has a time resolution of 1 ns, a mass resolution of ΔML = 2.24 amu, ΔMH = 1.54 amu, and energy resolution of ΔEL = 1.56 MeV, ΔEH = 1.08 MeV for the median light and median heavy fission fragments, respectively. A simple Range-Energy relation of the form R = KEα was fitted to the data points. K was found to be mass dependent and decreases with the increase of the ion mass. For α = 0.75, best range-energy results were obtained for K = 0.176 mg cm2/MeV0.75. K was determined from the values of the ranges and kinetic energies of the median light and median heavy fragments and then extrapolated to other masses.
Time-Resolved Spectroscopy of Accretion Disks in Algols

Time-resolved spectroscopy during the eclipse of short-period Algol systems, has shown their accretion disks to be small, turbulent structures with non-Keplerian velocity fields and asymmetries between the leading and trailing sides of the disk. These transient disks are produced by the impact of the gas stream on the mass-gaining star, and occur in systems where the star is just large enough to ensure the stream collision is complete. These emission line disks and the excess continuum emission do not always occur together. The permanent accretion disks in at least a few of the long-period Algol systems have features in common with the transient disks including non-Keplerian velocity fields.
Bounds on graph eigenvalues I

Abstract We prove three results about the spectral radius μ ( G ) of a graph G : (a) Let T r ( n ) be the r -partite Turan graph of order n . If G is a K r + 1 -free graph of order n , then μ ( G ) μ ( T r ( n ) ) unless G = T r ( n ) . (b) For most irregular graphs G of order n and size m , μ ( G ) - 2 m / n > 1 / ( 2 m + 2 n ) . (c) Let 0 ⩽ k ⩽ l . If G is a graph of order n with no K 2 + K ¯ k + 1 and no K 2 , l + 1 , then μ ( G ) ⩽ min G ) , ( k - l + 1 + ( k - l + 1 ) 2 + 4 l ( n - 1 ) ) / 2 } .
Toward a theoretical description of vortex wake asymmetry

Abstract Previous studies have suggested that the asymmetric vortex wake which develops behind an axisymmetric body at angle of attack is the result of the amplification of a disturbance introduced at the tip of the body. The potential-flow vortex wake of a circular cylinder in cross-flow is examined and similarities to the wake of the axisymmetric body at incidence are described. The implications of these similarities for the suggested model are discussed, and an argument is made that the vortex trajectories are fixed at a given angle of attack and shifted upstream or downstream by the initial disturbance. The need for further detailed experimental studies of the asymmetric vortex wake development is noted.
Right division in groups, dedekind-frobenius group matrices, and ward quasigroups

The variety of quasigroups satisfying the identity (xy)(zy) = xz mirrors the variety of groups, and offers a new look at groups and their multiplication tables. Such quasigroups are constructed from a group using right division instead of multiplication. Their multiplication tables consist of circulant blocks which have additional symmetries and have a concise presentation. These tables are a reincarnation of the group matrices which Frobenius used to give the first account of group representation theory. Our results imply that every group matrix may be written as a block circulant matrix and that this result leads to partial diagonalization of group matrices, which are present in modern applied mathematics. We also discuss right division in loops with the antiautomorphic inverse property.
Manganese Cluster in Photosynthesis: Where Plants Oxidize Water to Dioxygen

The essential involvement of manganese in photosynthetic water oxidation was implicit in the observation by Pirson in 1937 that plants and algae deprived of Mn in their growth medium lost the ability to evolve O{sub 2}. Addition of this essential element to the growth medium resulted in the restoration of water oxidation within 30 min. There is increased interest in the study of Mn in biological chemistry and dioxygen metabolism in the last two decades with the discovery of several Mn redox enzymes. The list of enzymes where Mn is required for redox activity includes a Mn superoxide dismutase, a binuclear Mn-containing catalase, a binuclear Mn-containing ribonucleotide reductase, a proposed binuclear Mn site in thiosulfate oxidase, a Mn peroxidase that is capable of oxidative degradation of lignin, and perhaps the most complex and important, the tetranuclear Mn-containing oxygen-evolving complex in photosystem II (Mn-OEC). Mn is well suited for the redox role with accessible oxidation states of II, III, and IV, and possibly V: oxidation states that have all been proposed to explain the mechanisms of the Mn redox enzymes.
Roots, reasons, and resources: Situated optimism and firm growth in subsistence economies☆

Abstract Do entrepreneurs have optimism in subsistence economies, and if so, how does it influence entrepreneurial outcomes? We investigate this question by taking the situated view of optimism. We reason that variations in optimism are a function of the type of opportunity pursued and the diversity of opportunity information entrepreneurs receive and that optimism plays an intervening role between these antecedents and business growth. We also hypothesize that this mediating relationship is conditioned on the reason for business formation (i.e., opportunity/necessity) and the level of microcredit loans. We test our model using survey data collected from more than 1000 entrepreneurs in Kenya, Burundi, and Indonesia. Our findings support the idea that optimism is an important determinant of business growth, but it is conditioned and altered by other salient factors.
Co-alignment in the resource–performance relationship: strategy as mediator

Abstract Small firms face unique challenges in crafting strategies that best utilize their resource bases. Research shows strategies that combine with resources lead to performance. The entrepreneurship literature finds the contingent effects, or moderating roles, of strategy and external factors, but the relationship between firm strategy and internal factors, such as resources, is less well studied. Based on the contention that the quality of a firm's strategy cannot be judged independently of the resources upon which it is based, we examine the relationship between firm resources, strategies, and performance in a cross-section of 192 small firms. Using a structural equation analysis, we examine the mediating role of firm strategies as they lead to firm performance in small firms operating in traditional industries. Our findings demonstrate that neither resources nor strategies alone explain firm performance, but instead, small firms fit their strategies to their resource profiles. Human and organizational resources in combination with a strategy of quality/customer service enhance firm performance.
Ballistic Impact Response of Kevlar 49 and Zylon under Conditions Representing Jet Engine Fan Containment

A ballistic impact test program was conducted to provide validation data for the development of numerical models of blade out events in fabric containment systems. The impact response of two different fiber materials - Kevlar 49 (E.I. DuPont Nemours and Company) and Zylon AS (Toyobo Co., Ltd.) was studied by firing metal projectiles into dry woven fabric specimens using a gas gun. The shape, mass, orientation and velocity of the projectile were varied and recorded. In most cases the tests were designed such that the projectile would perforate the specimen, allowing measurement of the energy absorbed by the fabric. The results for both Zylon and Kevlar presented here represent a useful set of data for the purposes of establishing and validating numerical models for predicting the response of fabrics under conditions simulating those of a jet engine blade release situation. In addition some useful empirical observations were made regarding the effects of projectile orientation and the relative performance of the different materials.
Emergency department ultrasonography in the evaluation of hypotensive and normotensive children with blunt abdominal trauma

Abstract Purpose: The aim of this study was to evaluate the accuracy of emergency department (ED) ultrasound scan in identifying which children with blunt torso trauma have intraperitoneal fluid associated with intraabdominal injuries (IAI). Methods: The authors conducted a prospective, observational study of children ( Results: A total of 224 pediatric blunt trauma patients had ultrasound scan performed and were enrolled. Thirty-three patients had IAI with intraperitoneal fluid, and ultrasound scan was positive in 27. The accuracy of abdominal ultrasound for detecting intraperitoneal fluid associated with IAI was sensitivity, 82% (95% confidence interval [CI] 65% to 93%); specificity, 95% (95% CI 91% to 97%); positive predictive value, 73% (95% CI 56% to 86%); and negative predictive value, 97% (95% CI 93% to 99%). In the 13 patients who were hypotensive, ultrasound scan correctly identified intraperitoneal fluid in all 7 patients (sensitivity 100%) with IAI, and hemoperitoneum and was negative in all 6 patients (specificity 100%) who did not have hemoperitoneum. Nine patients had IAI without intraperitoneal fluid, and ultrasound scan result was negative for fluid in all 9. Conclusions: ED abdominal ultrasound scan used solely for the detection of intraperitoneal fluid in pediatric blunt trauma patients has a modest accuracy. Ultrasonography has the best test performance in those children who are hypotensive and should be obtained early in the ED evaluation of these patients. J Pediatr Surg 36:968-973. Copyright © 2001 by W.B. Saunders Company.
Bipolar-FET Combinational Power Transistors for Power Conversion Applications

Four bipolar-FET (field-effect transistor) combinational transistor configurations are compared from the application point of view. The configurations included are FET-Darlington (cascade), emitter-open switch (cascode), parallel configuration, and FET-gated bipolar transistors (FGT).
Sensitive observations of radio recombination lines in Orion and W51: the data and detection of systematic recombination line blueshifts proportional to impact broadening

Sensitive spectral observations made in two frequency bands near 6.0 and 17.6 GHz are described for Orion and W51. Using frequency switching we were able to achieve a dynamic range in excess of 10,000 without fitting sinusoidal or polynomial baselines. This enabled us to detect lines as weak as TA∼1 mK in these strong continuum sources. Hydrogen recombination lines with Δn as high as 25 have been detected in Orion. In the Orion data, where the lines are stronger, we have also detected a systematic shift in the line center frequencies proportional to linewidth that cannot be explained by normal optical depth effects.
A Simple and Unusual Bijection for Dyck Paths and its Consequences

In this paper we introduce a new bijection from the set of Dyck paths to itself. This bijection has the property that it maps statistics that appeared recently in the study of pattern- avoiding permutations into classical statistics on Dyck paths, whose distribution is easy to ob- tain. We also present a generalization of the bijection, as well as several applications of it to enumeration problems of statistics in restricted permutations.
Transition metal-catalyzed intramolecular [4 + 2] cycloadditions: Mechanistic and synthetic investigations

Abstract The nickel-catalyzed intramolecular cycloaddition of dienes with unactivatable alkynes is found to proceed under mild conditions while the corresponding Diels-Alder cycloaddition of the same substrates either fails or occurs only under forcing conditions. The nickel-catalyzed cycloaddition is also shown to occur with retention of stereochemistry and is not significantly influenced by electronic effects. Finally, the catalyzed process is shown to be applicable to the synthesis of angularly substituted bicycles, including the CD ring systems of steroids and vitamin D.
Upward flame spread on composite materials

Three existing models of upward flame spread were tested against intermediate-scale experiments on a vinyl ester/glass composite. Characterization of rate of heat release per unit area, needed as input to the models, was obtained at external radiant fluxes below the minimum for ignition by adaptation of a method due to Kulkarni. There are several limitations on the accuracy of the material characterization when applied to composites. Each of the flame spread models has definite limitations as well. Nevertheless, all three models produced predictions of spread behavior in sufficiently quantitative agreement with the experiments that they should prove useful for engineering analyses of flame spread potential.
Hardy spaces and boundary conditions from the Ising model

Functions in Hardy spaces on multiply-connected domains in the plane are given an explicit characterization in terms of a boundary condition inspired by the two-dimensional Ising model. The key underlying property is the positivity of a certain operator constructed inductively on the number of components of the boundary.
Content design issues in adaptive hyperbooks

We explore the design issues of adaptive hyperbooks in relation to how using hypermedia technology changes the nature of the traditional book. To address some of these issues we have developed and tested MetaLinks, an authoring tool and web server for adaptive hyperbooks. The system is designed to: 1) support inquiry, exploratory, or curiosity-driven learning in richly interconnected material; 2) support the construction and conceptualisation of content through three "epistemic" forms: narrative, network and hierarchy and 3) ameliorate a number of usability issues: disorientation, cognitive overload, poor narrative flow and poor conceptual flow. These goals are achieved through a number of interface and adaptive features, including "narrative smoothing", "custom depth control", and "thematic links".
Synthesis of unsymmetrical biaryls from arylsilacyclobutanes

Aryl(fluoro)silacyclobutanes and aryl(chloro)silacyclobutanes have been found to undergo cross-coupling reactions with aryl iodides. The rate of reaction and extent of homocoupling were dramaticall...
RNA folding and large N matrix theory

We formulate the RNA folding problem as an N × N matrix field theory. This matrix formalism allows us to give a systematic classification of the terms in the partition function according to their topological character. The theory is set up in such a way that the limit N →∞ yields the so-called secondary structure (Hartree theory). Tertiary structure and pseudo-knots are obtained by calculating the 1/N 2 corrections to the partition function. We propose a generalization of the Hartree recursion relation to generate the tertiary structure.  2002 Published by Elsevier Science B.V.
Fe(II)-Catalyzed Amination of Aromatic C-H Bonds via Ring Opening of 2H-Azirines: Synthesis of 2,3-Disubstituted Indoles

A general method for the synthesis of 2,3-disubstituted indoles is described. The key feature of this method is the amination of aromatic C−H bonds via FeCl2-catalyzed ring opening of 2H-azirines. The method tolerates a variety of functional groups such as Br, F, NO2, OMe, CF3, OTBS, alkenes, and OPiv. The method can also be extended to synthesize azaindoles.
S-Arithmetic Khintchine-Type Theorem

In this article we prove a convergence S-arithmetic Khintchine-type theorem for the product of non-degenerate ν-adic manifolds, where one of them is the Archimedean place.
Cost-recovering bayesian algorithmic mechanism design

We study the design of Bayesian incentive compatible mechanisms in single parameter domains, for the objective of optimizing social efficiency as measured by social cost. In the problems we consider, a group of participants compete to receive service from a mechanism that can provide such services at a cost. The mechanism wishes to choose which agents to serve in order to maximize social efficiency, but is not willing to suffer an expected loss: the agents' payments should cover the cost of service in expectation.We develop a general method for converting arbitrary approximation algorithms for the underlying optimization problem into Bayesian incentive compatible mechanisms that are cost-recovering in expectation. In particular, we give polynomial time black-box reductions from the mechanism design problem to the problem of designing a social cost minimization algorithm without incentive constraints. Our reduction increases the expected social cost of the given algorithm by a factor of O(log(min{n, h})), where $n$ is the number of agents and h is the ratio between the highest and lowest nonzero valuations in the support. We also provide a lower bound illustrating that this inflation of the social cost is essential: no BIC cost-recovering mechanism can achieve an approximation factor better than Ω(log(n)) or Ω(log(h)) in general.Our techniques extend to show that a certain class of truthful algorithms can be made cost-recovering in the non-Bayesian setting, in such a way that the approximation factor degrades by at most O(log(min{n, h})). This is an improvement over previously-known constructions with inflation factor O(log n).
Photon Antibunching in Resonance Fluorescence

The phenomenon of antibunching of photoelectric counts has been observed in resonance fluorescence experiments in which sodium atoms are continuously excited by a dye-laser beam. It is pointed out that, unlike photoelectric bunching, which can be given a semiclassical interpretation, antibunching is understandable only in terms of a quantized electromagnetic field. The measurement also provides rather direct evidence for an atom undergoing a quantum jump.
On the convergence of the Calabi flow

Suppose there is a constant scalar curvature metric on a compact Kahler manifold without holomorphic vector field. We prove that the Calabi flow, if it is assumed to exist for all time with bounded Ricci curvature, will converge to the constant scalar curvature metric.
Experiments with strontium in a vapor cell magneto-optic trap

ABSTRACT In a ceramic vapor cell we have created a robust Sr magneto-optical trap that stores about 108 atoms with lifetimes>200 ms. We eliminate the 5p 1P14d 1D2*5p 3P2 leak and achieve a 10-fold improvement in trap lifetime byrepumping the 5p 3Po,2 dark states with 679 nm and 707 nm light. The observed lifetime is now limited by coldcollision losses, and we have preliminary measurements of the 2-body loss rate. Direct readout of the trap velocity distribution is possible using the narrow (7 kHz) 52 'S0----5p 3P1 intercombination line at 689 nm. We can also cool with this narrow transition and have achieved a 40-fold 1-D velocity compression for about 5% of the trapped atoms by applying this second-stage cooling. Keywords: Laser cooling, laser trapping, alkaline earths, cold collisions, frequency metrology 1. INTRODUCTION Laser cooling and trapping techniques have advanced to become an important tool of the atomic physics community, and in recent years there has been considerable interest in expanding the range of trapped elements. The alkalineearths, in particular, possess unique characteristics which make them interesting to trap. Studies of long-rangeatom-atom interactions are simplified because they have no hyperfine structure, and their narrow intercombinationtransitions make them excellent candidates for optical frequency standards. Furthermore, Doppler cooling with thesenarrow transitions can reduce temperatures to near the recoil limit.The most abundant alkaline earth isotopes have I =
The integral monodromy of hyperelliptic and trielliptic curves

We compute the $$\mathbb{Z}/\ell$$ and $$\mathbb{Z}_{\ell}$$ monodromy of every irreducible component of the moduli spaces of hyperelliptic and trielliptic curves. In particular, we provide a proof that the $$\mathbb{Z}/\ell$$ monodromy of the moduli space of hyperelliptic curves of genus g is the symplectic group $${\rm S}_{P2g}(\mathbb{Z}/\ell)$$ . We prove that the $$\mathbb{Z}/\ell$$ monodromy of the moduli space of trielliptic curves with signature (r,s) is the special unitary group $${\rm SU}_{(r,s)}(\mathbb{Z}/\ell\otimes\mathbb{Z}[\zeta_{3}])$$ .
Phase diagram of the Nb–Al–Si ternary system

Abstract A high-efficiency diffusion-multiple approach was employed to map the phase diagram of the Nb–Al–Si ternary system which is very valuable for the design of niobium silicide-based composites. These composites have high potential as a replacement for Ni-base superalloys for jet engine applications. Aluminum is an alloying element for these composites, thus the Nb–Al–Si phase diagram, especially solubility of Al in Nb5Si3, is important information for the composite design. An isothermal section at 1000 °C was constructed from the results obtained from a diffusion multiple using scanning electron microscopy (SEM) and electron probe microanalysis (EPMA). A ternary phase Nb3Si5Al2 was observed. The solubility data of Al in αNb5Si3 and NbSi2 as well as Si solubility in Nb3Al, Nb2Al and NbAl3 were obtained. The new isothermal section helps to judge the reliability of the existing literature results and to add new data to the Nb–Al–Si phase equilibria.
Problem oriented protocol design

The prevention of deadlock in certain types of distributed simulation systems requires special synchronization protocols. These protocols often create an excessive amount of performance-degrading communication; yet a protocol with the minimum amount of communication may not lead to the fastest network finishing time. We propose a protocol that attempts to balance the network's need for auxiliary synchronization information with the cost of providing that information. Using an empirical study, we demonstrate the efficiency of this protocol. Also, we show that the synchronization requirements at different interfaces may vary; an integral part of our proposal assigns a protocol to an interface according to the interface's synchronization needs.
Tide gauge and GPS measurements of crustal motion and sea level rise along the eastern margin of Adria

[1] We use observations from tide gauges and colocated continuous GPS (CGPS) stations to investigate crustal deformation and sea level changes along the eastern margin of the Adriatic Sea. We develop a new method to separate common-mode relative sea level from spatially variable signals. Precise vertical crustal motions determined by CGPS allow us to further separate relative sea level into absolute sea level changes and crustal motions with respect to a local Central Mediterranean–fixed GPS-defined reference frame. From the tide gauge data, we find fairly uniform relative sea level rise along the coast, with mean rate of 0.84 ± 0.04 mm/yr and weighted RMS variation about this mean of 0.2 mm/yr. This rate is a factor of 2–4 lower than estimates for global average sea level rise. In contrast, vertical motion of coastal rocks determined by CGPS vary appreciably from an average of −1.7 ± 0.4 mm/yr in southern Adria to 0.0 ± 0.4 mm/yr in northern Adria. This difference in crustal motion between the northern and southern regions is independent of our ability to separate sea level from crustal motion, and may be explained by crustal strain associated with an active thrust fault accommodating southern Adria microplate convergence with Eurasia. Enigmatically, the combination of tide gauge and CGPS measurements shows that absolute sea level relative to the GPS-determined reference frame varies by as much as ∼1.8 mm/yr along the Croatian coast in such a way that the relative sea level remains roughly constant. There are several potential explanations for this result deriving from ocean, atmosphere, and solid Earth dynamics.
Dynamic optical correlation using localized holography.

A new technique for optical correlation using gated holographic recording is demonstrated. Several persistent holograms are localized within separate slices as close as 33 μm apart along the crystal. Individual holograms can be dynamically erased and rerecorded with no need to refresh all other recorded holograms. Experimental results showing the correlation capability, cross talk, shift invariance, and dynamicity of the localized holographic correlator demonstrate unique performance and capabilities for these correlators.