cssi/SciSciGPT-SciSciNet huggingface dataset:
Camera for conical peripheral and panoramic photography

This paper is a report on the development, operating principles and applications of a camera capable of making distortion free peripheral reproductions of conical objects. In addition, the parameters governing its use for the generation of conical panoramic photographs are also described. Examples of both types of applications are included. Suggestions for other applications are given. A brief review of the operating principles of standard peripheral, panoramic and linear type strip cameras is included in the introduction to the paper.
Early Growth and Efficient Accretion of Massive Black Holes at High Redshift

Black hole masses of the highest redshift quasars (4 z 6) are estimated using a previously presented scaling relationship, derived from reverberation mapping of nearby quasars, and compared with quasars at lower redshift. It is shown that the central black holes in luminous z 4 quasars are very massive (109 M☉). It is argued that the mass estimates of the high-redshift quasars are not subject to larger uncertainties than those for nearby quasars. Specifically, the large masses are not overestimates, and the lack of similarly large black hole masses in the nearby universe does not rule out their existence at high redshift. However, active galactic nucleus host galaxies do not typically appear fully formed and/or evolved at these early epochs. This supports scenarios in which black holes build up mass very fast in a radiatively inefficient (or obscured) phase relative to the stars in their galaxies. In addition, upper envelopes of MBH ≈ 1010 M☉ and Lbol ≈ 1048 ergs s-1 are observed at all redshifts.
Wind Heat Loss From Corrugated, Transpired Solar Collectors

Heat transfer from a perforated, sinusoidal plate with suction to air flowing over the plate, perpendicular to the corrugations, has been studied numerically and experimentally. This study used a numerical model, validated by wind tunnel tests and hot wire anemometer/resistance thermometer measurements, to determine the heat loss to the air stream over the plate as a function of wind speed, suction velocity, and plate geometry. Both attached and separated flow regimes were observed, and the criterion for flow attachment was determined to be Re V0,P ≥6.93 Re 0.5 U ∞ ,A . Correlations were developed for heat transfer to the air stream for each flow regime. For attached flow, the heat transfer can be represented as Nu att = Nu falat {1 +0.81(A/P) 0.5 }. For separated flow, the following correlation applies: Nu sep = 2.05(A/P) 1.40 Re 1.63 .
A self‐regulating model of bedrock river channel geometry

[1] The evolution of many mountain landscapes is controlled by the incision of bedrock river channels. While the rate of incision is set by channel shape through its mediation of flow, the channel shape is itself set by the history of bedrock erosion. This feedback between channel geometry and incision determines the speed of landscape response to tectonic or climatic forcing. Here, a model for the dynamics of bedrock channel shape is derived from geometric arguments, a normal flow approximation for channel flow, and a threshold bed shear stress assumption for bedrock abrasion. The model dynamics describe the competing effects of channel widening, tilting, bending, and variable flow depth. Transient solutions suggest that channels may take ∼1–10 ky to adapt to changes in discharge, implying that channel disequilibrium is commonplace. If so, landscape evolution models will need to include bedrock channel dynamics if they are to probe the effects of climate change.
Palladium-Catalyzed Suzuki-Miyaura Cross-coupling Reactions Employing Dialkylbiaryl Phosphine Ligands

The cores of many types of polymers, ligands, natural products, and pharmaceuticals contain biaryl or substituted aromatic structures, and efficient methods of synthesizing these structures are crucial to the work of a broad spectrum of organic chemists. Recently, Pd-catalyzed carbon−carbon bond-forming processes, particularly the Suzuki−Miyaura cross-coupling reaction (SMC), have risen in popularity for this purpose. The SMC has many advantages over other methods for constructing these moieties, including mild conditions, high tolerance toward functional groups, the commercial availability and stability of its reagents, and the ease of handling and separating byproducts from its reaction mixtures. Until 1998, most catalysts for the SMC employed triarylphosphine ligands. More recently, new bulky and electron-rich phosphine ligands, which can dramatically improve the efficiency and selectivity of such cross-coupling reactions, have been introduced. In the course of our studies on carbon−nitrogen bond-formi...
RADIO AND MID-INFRARED PROPERTIES OF COMPACT STARBURSTS: DISTANCING THEMSELVES FROM THE MAIN SEQUENCE

We investigate the relationship between 8.44 GHz brightness temperatures and 1.4 to 8.44 GHz radio spectral indices with 6.2 μm polycyclic aromatic hydrocarbon (PAH) emission and 9.7 μm silicate absorption features for a sample of 36 local luminous and ultraluminous infrared galaxies. We find that galaxies having small 6.2 μm PAH equivalent widths (EQWs), which signal the presence of weak PAH emission and/or an excess of very hot dust, also have flat spectral indices. The three active galactic nuclei (AGN) identified through their excessively large 8.44 GHz brightness temperatures are also identified as AGN via their small 6.2 μm PAH EQWs. We also find that the flattening of the radio spectrum increases with increasing silicate optical depth, 8.44 GHz brightness temperature, and decreasing size of the radio source even after removing potential AGN, supporting the idea that compact starbursts show spectral flattening as the result of increased free-free absorption. These correlations additionally suggest that the dust obscuration in these galaxies must largely be coming from the vicinity of the compact starburst itself, and is not distributed throughout the (foreground) disk of the galaxy. Finally, we investigate the location of these infrared-bright systems relative to the main sequence (star formation rate versus stellar mass) of star-forming galaxies in the local universe. We find that the radio spectral indices of galaxies flatten with increasing distance above the main sequence, or in other words, with increasing specific star formation rate. This indicates that galaxies located above the main sequence, having high specific star formation rates, are typically compact starbursts hosting deeply embedded star formation that becomes more optically thick in the radio and infrared with increased distance above the main sequence.
Can the Markov switching model forecast exchange rates

Abstract A Markov-swirching model is fit for 18 exchange rates at quarterly frequencies. The model fits well in-sample for many exchange rates. By the mean-squared-error criterion, the Markov model does not generate superior forecasts to a random walk or the forward rate. There appears to ne some evidence that the forecasts of the Markov model are superior at predicting the direction of change of the exchange rate.
Widely Separated Clocks with Microsecond Synchronization and Independent Distribution Systems

In a majority of timing applications, a problem exists in setting two or more clocks to agree with one another. Present techniques using WWV or other HF broadcasts allow clocks to be synchronized within 1 msec. This paper describes a method which offers an improvement in synchronization of three orders of magnitude. Microsecond synchronization is obtained by use of the Loran-C navigation system as the link between a master clock at Boulder, Colorado and any slaved clock anywhere in the Loran-C service area. The timing system also includes a unique method for distribution of several time code formats on a single UHF channel.
Quantum many-body interactions in digital oxide superlattices

The electronic interactions at the interface of oxide materials promise properties that can be very different from those of the parent compounds. The finding that many-body interactions in oxide superlattices can be used to engineer electronic properties offers a new strategy for designing oxide heterostructures.
EFFICIENT PAIRING FUNCTIONS — AND WHY YOU SHOULD CARE

This paper provides a short guided tour through the world of pairing functions—bijections between and —as models for computational "situations." After a short discussion of the computationally simplest pairing functions—the Cauchy-Cantor "diagonal" polynomials—we describe in detail two specific computational situations where pairing functions give an unexpectedly simple handle on apparently complex systems-related problems. (1) We discuss the use of pairing functions as storage mappings for rectangular arrays/tables that are extendible, in the sense that the programmer may expand and shrink them dynamically. (2) We discuss the use of pairing functions as the basis for a mechanism for instilling accountability into Web-computing projects, by linking remote "volunteers" to the tasks they compute.
ARE THERE MORE FEMALE MANAGERS IN THE RETAIL SECTOR? EVIDENCE FROM SURVEY DATA IN DEVELOPING COUNTRIES

This paper uses firm-level data for 87 developing countries to analyze how the likelihood of a firm having female vs. male top manager varies across sectors. The service sector is often considered to be more favorable toward women compared with men vis-a-vis the manufacturing sector. Although the exploration of the data confirms a significantly higher presence of female managers in services vs. manufacturing, the finding is entirely driven by retail firms, with little contribution from other service sectors, such as wholesale, construction, and other services. The analysis also finds that the higher presence of female managers in the retail sector vs. manufacturing is much higher among the relatively small firms and firms located in the relatively small cities. These findings could serve as useful inputs for the design of optimal policy measures aimed at promoting gender equality in a country.
Double ionization by strong elliptically polarized laser pulses

We join the tribute to Professor N.B. Delone in this memorial issue by presenting the results of new calculations on the effects of ellipticity on double ionization by short and strong near-optical laser pulses.
On the kinematics of protein folding.

We offer simple solutions to three kinematic problems that occur in the folding of proteins. We show how to construct suitably local elementary Monte Carlo moves, how to close a loop, and how to fold a loop without breaking the bond that closes it. © 2003 Wiley Periodicals, Inc. J Comput Chem 24: 1364 -1370, 2003
Optimal extraction of cosmological information from supernova data in the presence of calibration uncertainties

We present a new technique to extract the cosmological information from high-redshift supernova data in the presence of calibration errors and extinction due to dust. While in the traditional technique the distance modulus of each supernova is determined separately, in our approach we determine all distance moduli at once, in a process that achieves a significant degree of self-calibration. The result is a much reduced sensitivity of the cosmological parameters to the calibration uncertainties. As an example, for a strawman mission similar to that outlined in the SNAP satellite proposal, the increased precision obtained with the new approach is roughly equivalent to a factor of five decrease in the calibration uncertainty.
Palladium/Copper (I) halide-cocatalyzed stereospecific coupling of 1-fluorovinylstannanes with aryl iodides and acyl chlorides

Abstract Cross-coupling of 1-fluorovinylstannanes with aryl iodides or acyl chlorides, cocatalyzed by palladium and copper (I) iodide proceeded under mild conditions to give substituted fluoro olefins and α-fluoro-α,β-unsaturated ketones, respectively, in good yields with retention of configuration.
Studies of p-shell nuclei by large momentum transfer electron scattering

Abstract The use of transverse electron scattering as a technique for studying the structure of 1p-shell nuclei is briefly reviewed. At the present time there exist unresolved problems such as missing strength in comparison with shell model calculations. At the same time, the observed cross sections fall off more slowly than expected at high momentum transfers. The derivation of phenomenological wave functions for the ground and 2.313 MeV states in 14 N is described.
Modeling and analysis of line-frequency converters by double-Fourier series methods

This paper presents modeling of line-frequency converters with and without phase control. The operation of the converters can be described by two algebraic equations based on defined mapping functions. Unlike previous work that develops the mapping functions using direct Fourier expansion, double-Fourier series method is applied to avoid the assumption on the perturbation frequency. The resulting mapping functions are not limited to small-signal perturbation as in the previous models and can be used to predict harmonic distortion as well as small-signal impedance. The method is applied to both uncontrolled and phase-controlled multipulse rectifiers and the resulting mapping function is also used to model the input impedance of phase-controlled converters.
Settling the Smoke: Public Policy and Shareholder Wealth in the Cigarette Industry

This article uses daily data on stock returns of five U.S. publicly traded cigarette producers to document the wealth effects of antismoking policies initiated in the period 1964 to 1971. The authors find significant abnormal returns across 23 dates corresponding to important regulatory events. The second-stage estimation shows that wealth effects are also influenced by firm characteristics, such as market share, advertising intensity, percentage of sales of filter-tip cigarettes, percentage of advertising expenditures devoted to TV and radio, and tobacco leaf inventories. Overall, the article estimates that industry losses from antismoking policies amounted to approximately $1.5 billion. (JEL L66, G14, I18)
Reduced complexity angle-Doppler-range estimation for MIMO radar that employs compressive sensing

The authors recently proposed a MIMO radar system that is implemented by a small wireless network. By applying compressive sensing (CS) at the receive nodes, the MIMO radar super-resolution can be achieved with far fewer observations than conventional approaches. This previous work considered the estimation of direction of arrival and Doppler. Since the targets are sparse in the angle-velocity space, target information can be extracted by solving an l 1 minimization problem. In this paper, the range information is exploited by introducing step frequency to MIMO radar with CS. The proposed approach is able to achieve high range resolution and also improve the ambiguous velocity. However, joint angle-Doppler-range estimation requires discretization of the angle-Doppler-range space which causes a sharp rise in the computational burden of the l 1 minimization problem. To maintain an acceptable complexity, a technique is proposed to successively estimate angle, Doppler and range in a decoupled fashion. The proposed approach can significantly reduce the complexity without sacrificing performance.
Efficacy and utility of computer‐assisted cognitive behavioural therapy for anxiety disorders

Despite the efficacy of cognitive behavioural treatment for anxiety disorders, more than 70% of individuals with anxiety disorders go untreated every year. This is partially due to obstacles to treatment including limited access to mental health services for rural residents, the expense of treatment and the inconvenience of attending weekly therapy sessions. Computer-assisted therapy may be a means of providing cost-effective psychological services to individuals experiencing barriers to treatment. To date, computers have been applied to therapy for anxiety disorder using various formats including Internet treatment, virtual reality treatment, videoconferencing and more standard computer-assisted or computer-guided packages that are implemented on palmtop computers or desktop computers. The current paper reviews trials evaluating the efficacy of these technology-based treatments for anxiety disorders and discusses implications for future research.
INTERNATIONAL CAPITAL MOBILITY AND TRADE POLITICS: CAPITAL FLOWS, POLITICAL COALITIONS, AND LOBBYING

Conventional wisdom holds that increasing international capital mobility reduces incentives for firms to lobby for trade protection. This paper argues that the effects of increased international capital mobility on the lobbying incentives of firms depend critically upon levels of inter-industry mobility. General-equilibrium analysis reveals that if capital is highly industry-specific, greater international mobility among some types of specific capital may increase lobbying incentives for owners of other specific factors and thereby intensify industry-based rent-seeking in trade politics. Evidence on levels of inward and outward investment in US manufacturing industries between 1982 and 1996, and on industry lobbying activities, indicate that these effects may be quite strong.
Accessing speech documents on smartphones

This paper introduces BBSearch, which is an experimental system for exploring the challenges of ubiquitous access to recorded speech data. BBSearch applies information retrieval techniques to transcripts obtained by automatic speech recognition and it aims to provide a uniform user experience across platforms. To provide identical search functionality and document ranking, BBSearch applications use the same IR library for indexing and retrieval, namely Apache Lucene. For Java-enabled mobile platforms, BBSearch uses our J2ME Lucene port, called LuceneME. This paper explores the resource requirements of LuceneME when used for Boolean searches and for supporting the podcast navigation GUI. On a BlackBerry smartphone, a diverse set of queries against a 70-hour corpus complete in less than 3 seconds and use less than 2MB of memory. The results of the evaluation validate our design and warrant expanding BBSearch to less capable cellphones, larger corpuses, or with more complex search capabilities.
The effect of monetary policy actions on exchange rates under interest-rate targeting

Abstract We specify a theoretical model of the exchange-rate response to U.S. monetary policy actions that is capable of explaining a wide range of recent empirical results. We show that the response pattern of spot and expected future exchange rates depends on the predictability of Federal Reserve actions, the persistence of shocks to the economy, and the reaction of foreign central banks to the US monetary policy shock. We also show that the movements of spot and expected future exchange rates in anticipation of a monetary policy change can outweigh the immediate responses at the time of the change.
Symmetry algebras of large-N matrix models for open strings

We have discovered that the gauge-invariant observables of matrix models invariant under U(N) form a Lie algebra, in the planar large-N limit. These models include Quantum Chromodynamics and the M(atrix) theory of strings. We study here the gauge-invariant states corresponding to open strings (‘mesons’). We find that the algebra is an extension of a remarkable new Lie algebra VΛ by a product of more well-known algebras such as gl+∞ and the Cuntz algebra. VΛ appears to be a generalization of the Lie algebra of vector fields on the circle to non-commutative geometry. We also use a representation of our Lie algebra to establish an isomorphism between certain matrix models (those that preserve ‘gluon number’) and open quantum spin chains. Using known results from quantum spin chains, we are able to identify some exactly solvable matrix models. Finally, the Hamiltonian of a dimensionally reduced QCD model is expressed explicitly as an element of our Lie algebra.
Elevated glucose alters paracellular transport of cultured human proximal tubule cells

Elevated glucose alters paracellular transport in cultured human proximal tubule cells. Cultures of human proximal tubule cells were exposed to elevated concentrations of glucose and dome formation was assessed over a 22 day period of growth. Cultures grown on 5.5mM glucose formed five domes per microscopic field while those exposed to elevated glucose concentrations (11.0mM to 27.5mM) formed only two to three domes per field. The areas of the domes formed by the cells grown on elevated glucose concentrations were reduced as compared to those formed on 5.5mM glucose. An analysis of the electrical properties of cells grown on elevated glucose concentrations by Ussing chamber technique disclosed a marked reduction in potential difference, short circuit current, and resistance compared to cells grown on 5.5mM glucose. Routine ultrastructural analysis disclosed that cells grown on elevated glucose concentrations appeared to have fewer tight junction complexes. Further examination utilizing freeze fracture methodology demonstrated that cells grown on elevated glucose concentrations averaged two to three sealing strands per junction as compared to an average of five sealing strands for cells grown on 5.5mM glucose. The cells grown on elevated glucose concentrations were also noted to possess a greater number of gap junctions. These results demonstrate that elevated glucose concentrations can alter the paracellular route, and possibly the transcellular route, of transport regulation in cultured human proximal tubule cells.
Gravitational perturbation and quasi-normal modes of charged black holes in Einstein–Born–Infeld gravity

Born–Infeld electrodynamics has attracted considerable interest due to its relation to strings and D-branes. In this paper the gravitational perturbations of electrically charged black holes in Einstein–Born–Infeld gravity are studied. The effective potentials for axial perturbations are derived and discussed. The quasi normal modes for the gravitational perturbations are computed using a WKB method. The modes are compared with those of the Reissner–Nordstrom black hole. The relation of the quasi normal modes with the non-linear parameter and the spherical index are also investigated. Comments on stability of the black hole and on future directions are made
Handling qualities research at the National Aeronautical Establishment, Ottawa, using airborne V/STOL simulators.

A brief description of the two V/STOL aircraft simulators operated by the National Aeronautical Establishment will be presented. One of these variable stability helicopters lias the capability of varying its characteristics in the three rotational degrees of freedom over wide limits and has been flying for several years. The other uses the same basic "model-controlled" method of simulation but has many improvements including the capacity to alter its response in the vertical or heave degree of freedom. These aircraft have been used for general research into V/STOL handling qualities requirements and for simulation of particular aircraft. An investigation into the effects of weathercock stability on directional handling qualities during both visual and simulated instrument flying tasks illustrated the pilots' desire for higher levels of angular rate damping while flying on instruments. A simulation of a tilt-wing V/STOL aircraft, the Canadair CL-84, indicated maximum satisfactory and acceptable levels of backlash and flexibility in the flight control systems with the stability augmentation system fully operative arid following a variety of selected failures.
The space of compatible full conditionals is a unimodular toric variety

The set of all m-tuples of compatible full conditional distributions on discrete random variables is an algebraic set whose defining ideal is a unimodular toric ideal. We identify the defining polynomials of these ideals with closed walks on a bipartite graph. Our algebraic characterization provides a natural generalization of the requirement that compatible conditionals have identical odds ratios and holds regardless of the patterns of zeros in the conditional arrays.
Chemistry and anticarcinogenic mechanisms of glycoalkaloids produced by eggplants, potatoes, and tomatoes.

Inhibition of cancer can occur via apoptosis, a genetically directed process of cell self-destruction that involves numerous biomarkers and signaling pathways. Glycoalkaloids are nitrogen-containing secondary plant metabolites found in numerous Solanaceous plants including eggplants, potatoes, and tomatoes. Exposure of cancer cells to glycoalkaloids produced by eggplants (α-solamargine and α-solasonine), potatoes (α-chaconine and α-solanine), and tomatoes (α-tomatine) or their hydrolysis products (mono-, di-, and trisaccharide derivatives and the aglycones solasodine, solanidine, and tomatidine) inhibits the growth of the cells in culture (in vitro) as well as tumor growth in vivo. This overview comprehensively surveys and consolidates worldwide efforts to define the following aspects of these natural compounds: (a) their prevalence in the three foods; (b) their chemistry and structure–activity relationships; (c) the reported factors (biomarkers, signaling pathways) associated with apoptosis of bone, brea...
Hydrogen in the upper atmosphere

Over the last 4 years researchers in the United States have made important contributions to the noticeable improvement of our knowledge of hydrogen in the upper atmosphere. In addition to new data being obtained in rocket, satellite, and ground-based measurements, improved interpretation of the data and understanding of background effects have lead to more reliable results on hydrogen abundances and diurnal and other variations. Theoretical and observational progress has been made in the understanding of the vertical profiles, the diurnal variations, and the nature of sources and sinks for hydrogen in the upper atmosphere. The effect of hydrogen escape on the evolution of oxygen in the earth's atmosphere has been reinterpreted.
Role of Lewis Acidity in the Isomerization of n-Pentane and o-Xylene on Dealuminated H-Mordenites

Abstract n -Pentane and o -xylene isomerizations have been studied at 285 and 150°C, respectively, on seven dealuminated H-mordenites containing different amounts of framework and nonframework aluminum which were prepared by steaming or calcining NH 4 -mordenite. The number of Bronsted and Lewis sites were known beforehand from 29 S high-resolution magnetic resonance and infrared study of low-temperature CO adsorption. In addition, the availability of the acid sites to the reactants was estimated from the ratios of the liquid monolayer volume of the reactant ( n -pentane or o -xylene) to that of N 2 , the availability of the active sites to N 2 and CO being the same. It was observed that the initial rates of isomerization divided by the number of available Bronsted sites are proportional to the number of available Lewis sites. This observation suggests a synergistic enhancement of the acidity by the interaction between Bronsted and Lewis acid centers. Other aspects related with the products distribution are also discussed.
Secular Stability and Instability in Stellar Systems Surrounding Massive Objects

We examine the stability of a low-mass stellar system surrounding a massive central object. Examples of such systems include the centers of galaxies or star clusters containing a massive black hole and the Oort comet cloud. If the self-gravity of the stellar system is the dominant non-Keplerian force, such systems may be subject to slowly growing (secular) lopsided instabilities. Stability to secular modes is largely determined by the dependence of the distribution function F on angular momentum J. If ∂F/∂J 0, as is expected if there is a loss cone at low angular momentum, all spherical systems in which F = 0 at J = 0 (an empty loss cone) are only neutrally stable, and flattened, nonrotating systems are generally unstable. These results suggest that secular instabilities may dominate the structure and evolution of the stellar systems in the centers of galaxies.
Emission impacts of electric vehicles

Alternative vehicular fuels are proposed as a strategy to reduce urban air pollution. In this paper, we analyze the emission impacts of electric vehicles in California for two target years, 1995 and 2010. We consider a range of assumptions regarding electricity consumption of electric vehicles, emission control technologies for power plants, and the mix of primary energy sources for electricity generation. We find that, relative to continued use of gasoline-powered vehicles, the use of electric vehicles would dramatically and unequivocally reduce carbon monoxide and hydrocarbons. Under most conditions, nitrogen oxide emissions would decrease moderately. Sulfur oxide and particulate emissions would increase or slightly decrease. Because other areas of the United States tend to use more coal in electricity generation and have less stringent emission controls on power plants, electric vehicles may have less emission reduction benefits outside California.
KMnAg3(CN)6, a new triply interpenetrating network solid

The single-crystal structure of potassium manganese tris[dicyanoargentate(I)], KMnAg(3)(CN)(6), is described. This is the first Mn-containing example of the triply interpenetrating MAg(3)(CN)(6) type. The K(+) ion is found to be located in an ordered manner on one of two possible interstitial sites, leading to a chiral space group.
Pressure effects on the electronic structure of 4f and 5f materials

Abstract The γ-α transition in cerium has been the focus of considerable theoretical effort. It has been attributed to a Mott-like transition of the 4f electrons from localized to itinerant character, as well as to volume sensitivity of the Kondo binding energy, to mention two of the explanations. Less attention has been directed towards analogous transitions observed at higher pressures in praseodymium, neodymium and samarium among the elemental 4f metals; and in americium, curium, berkelium and californium among the 5f metals. This paper reviews our current theoretical understanding of the evolution in electronic structure which underlies these dramatic transitions in compressed 4f and 5f materials.
Dual-SiC photodiode devices for simultaneous two-band detection

SiC is a highly useful material for optical sensing devices in the UV due to its large bandgap. It also exhibits a robust physical nature, making it suitable for harsh environment applications such as flame sensing. Here we report the first demonstration of SiC photodiode devices with multiple, independent detection components for sensing more than one radiation band simultaneously. The fabrication process and layout of the devices is described along with optical and electrical measurements of their performance. Individual sensing components exhibited peak responsivities greater than 60 mA/W at wavelengths of 290 and 320 nm. Optically tailored SiC devices, such as the ones described here, may further be applied to other applications such as missile plume detection, engine control, and communications in the solar-blind window. The application of particular interest for these devices was for flame temperature sensing. Testing the dual-SiC photodiode devices in front of a combustion flame showed a significant and linear dependence of the photodiode's output ratio with temperature, demonstrating its feasibility. Successful determination of flame temperature would be a major improvement in the control and optimization of combustion processes.
The Revamping of an Ignition Test Facility

The revamping of an Ignition Test Facility, located in the Research Combustion Laboratory at the NASA Glenn Research Center, is presented. The history of how the test cell has adapted efficiently to a variety of test programs is discussed. The addition of a second test stand for ignition and small-scale rocket testing is detailed. An overview of the facility and the current test programs is offered. Planned upgrades for the future are outlined.
Instrumental background in balloon-borne gamma-ray spectrometers and techniques for its reduction

Instrumental background in balloon-borne gamma-ray spectrometers is presented. The calculations are based on newly available interaction cross sections and new analytic techniques, and are the most detailed and accurate published to date. Results compare well with measurements made in the 20 keV to 10 MeV energy range by the Goddard Low Energy Gamma-ray Spectrometer (LEGS). The principal components of the continuum background in spectrometers with GE detectors and thick active shields are: (1) elastic neutron scattering of atmospheric neutrons on the Ge nuclei; (2) aperture flux of atmospheric and cosmic gamma rays; (3) beta decays of unstable nuclides produced by nuclear interactions of atmospheric protons and neutrons with Ge nuclei; and (4) shield leakage of atmospheric gamma rays. The improved understanding of these components leads to several recommended techniques for reducing the background.
INVARIANT REPRESENTATION AND HIERARCHICAL NETWORK FOR INSPECTION OF NUTS FROM X-RAY IMAGES

An X-ray based system for the inspection of pistachio nuts and wheat kernels for internal insect infestation is presented. The novelty of this system is two-fold. First, we construct an invariant representation of infested nuts from X-ray images that is rich, robust, and compact. Insect infestation creates a tunnel, in the X-ray image, with reduced density of the natural material. The tunneling effect is encoded by linking troughs on the image and constructing a joint curvature-proximity distribution table for each nut. The latter step is designed to accentuate separation of those tunneling effects that are due to the natural structure of the nut. Second, since the representation is sparse, we partition the joint distribution table into several regions, where each region is used independently to train a backpropagation (BP) network. The outputs of these subnets are then collectively trained with another BP network. We show that the resulting hierarchical network has the advantage of reduced dimensionality while maintaining a performance similar to the standard BP network.
A proof of the classification theorem of overtwisted contact structures via convex surface theory

In Contact 3-manifolds, twenty years since J. Martinet’s work, Eliashberg proved that two overtwisted contact structures on a closed oriented 3-manifold are isotopic through contact structures if and only if they are homotopic as 2-plane fields. We provide an alternative proof of this theorem using the convex surface theory and bypasses.
The Evolution and Eddington Ratio Distribution of Compton Thick Active Galactic Nuclei

Previous studies of the active galactic nuclei (AGNs) contribution to the cosmic X-ray background (CXB) consider only observable parameters such as luminosity and absorbing column. Here, for the first time, we extend the study of the CXB to physical parameters including the Eddington ratio of the sources and the black hole mass. In order to calculate the contribution to the CXB of AGN accreting at various Eddington ratios, an evolving Eddington ratio space density model is calculated. In particular, Compton thick (CT) AGNs are modeled as accreting at specific, physically motivated Eddington ratios instead of as a simple extension of the Compton thin type 2 AGN population. Comparing against the observed CT AGN space densities and log N-log S relation indicates that CT AGNs are likely a composite population of AGNs made up of sources accreting either at >90% or <1% of their Eddington rate.
Stabilizability of nonholonomic control systems

Abstract We consider here the problem of stabilization of nonlinear Hamiltonian control systems with nonholonomic constraints. Such systems are of interest in various applications including the control of robotic systems. We discuss the formulation of Hamiltonian systems with nonholonomic constraints, in particular considering the differences between the Dirac theory of constraints, the classical theory of nonholonomic constraints, and Weber's theory of generalized nonholonomic constraints. Stabilization of systems with these constraints is discussed using the theory of Hamiltonian control systems, and a reduced stabilization criterion is given.
Intraamniotic Bleeding Following Transabdominal Amniocentesis

A prospective study on 231 consecutive patients who underwent transabdominal genetic amniocentesis was performed to determine the incidence of intraamniotic bleeding associated with needle removal and to determine if this increased future pregnancy complications. Eleven procedures traversed the placenta and intraamniotic bleeding was seen in every case. In 220 cases the placenta was not traversed and intraamniotic uterine wall bleeding was seen in 38%. In 92% of these, bleeding stopped in less than 30 sec. No difference in pregnancy outcome was seen between cases with visible bleeding when compared to cases where bleeding was not identified, suggesting that this is a normal but unavoidable aspect of amniocentesis. The location of the placenta was not a factor except that a transplacental procedure was more likely with an anterior placenta. Possible explanations for this unexpected high incidence are discussed as well as the theoretical concern over exposing the unborn fetus to maternal blood borne infections.
Cooperativity of Regiochemistry Control Strategies in Reductive Couplings of Propargyl Alcohols and Aldehydes

The nickel-catalyzed reductive coupling of propargyl alcohols and alkynes proceeds with excellent regiochemical control with an underlying electronic preference that can be supplemented by ligand size effects. The products obtained may be readily converted to substructures that are not directly available by an aldehyde−alkyne reductive coupling. A simple model for how steric and electronic factors are both important in governing regiochemistry in couplings of this type is presented, along with examples of how the effects can combine in either a constructive or destructive manner.
Visible and near-infrared emittance of ablation chars and carbon.

Initial results of an experimental study of the visible and near-infrared spectral reflectance and emittance of ablation chars, carbon, and graphite at temperatures ranging from 2200° to 3500° K are presented. Reflectance measurements were made with a double-ellipso idalmirror reflectometer that utilizes a carbon arc to heat and to irradiate the materials. The ablation materials, from which the chars were formed by thermal degradation in atmosphericentry-simulation facilities, included high-density and low-density phenolic-nylon, carbonfiber-reinforced phenolic, and honeycomb-reinforced, low-density filled epoxy. Measurements were made on a dense high-purity and a porous grade of carbon and on high-purity, structural, and pyrolytic grades of graphite. A photomultiplier and a lead sulfide cell were used as detectors for the visible and infrared measurements, respectively. The results indicate that emittance for all the materials is maximum in the visible spectrum and decreases with wavelength in the near-infrared spectrum. The angular distributions of radiation fluxes incident on, reflected from, and radiated from, each material, were measured with an array of solar cells. The distribution measurements showed that the materials whose surfaces are porous or have been roughened by oxidation obey Lambert's cosine law approximately in the emission of radiation, and also in reflecting the arc incident radiation, although the incident radiation is nonuniform in distribution.
Reactions at polymer interfaces: Transitions from chemical to diffusion-control and mixed order kinetics

We study reactions between end-functionalized chains at a polymer-polymer interface. For small chemical reactivities (the typical case) the number of diblocks formed, t, obeys 2nd-order chemically controlled kinetics, t ~ t, until interfacial saturation. For high reactivities (e.g., radicals) a transition occurs at short times to 2nd-order diffusion-controlled kinetics, with t ~ t/ln t for unentangled chains while t/ln t and t1/2 regimes occur for entangled chains. Long-time kinetics are 1st order and controlled by diffusion of the more dilute species to the interface: t ~ t1/4 for unentangled cases, while t ~ t1/4 and t1/8 regimes arise for entangled systems. The final 1st-order regime is governed by center-of-gravity diffusion, t ~ t1/2.
Interaction between the solar plasma wind and the geomagnetic cavity

If the quiet-time interplanetary magnetic field near the earth is parallel to the solar wind, the flow of this "collision-free" plasma over the geomagnetic cavity is reducible to an equivalent hypersonic "blunt-body problem" in ordinary gasdynamics. The shape of the converging "tail" portion of the geomagnetic cavity is determined by an equivalent gasdynamic (PrandtlMeyer) expansion along the surface streamline. The length of the tail measured from the earth's center is about 54 earth-radii. At the aft end of the cavity, the converging plasma flow is deflected back to the axial direction across an oblique tail or "wake" shock, which decays to an Alfven wave in a distance of some 10-20 cavity diameters downstream, or about 300 earth-radii. The geomagnetic cavity leaves a wake of hot plasma in the solar wind, and a corresponding defect in magnetic field intensity. The effects of a transverse component of the interplanetary magnetic field are illustrated by considering the flow along the stagnation line between the bow shock and the stagnation point on the magnetosphere. The axial velocity and plasma density both vanish at the stagnation point, whereas the transverse magnetic field reaches its maximum value there. This discussion furnishes the necessary first step for the analysis of the flow and magnetic field around the magnetosphere.
Synthesis and structure-activity relationships of new second-generation taxoids.

Abstract A series of second-generation taxoids bearing a substitutent on the C-2-benzoyl group and modifications at C-3′/C-10 positions was synthesized. These taxoids exhibited 2–3 orders of magnitude higher potency than that of paclitaxel against drug-resistant human breast cancer cell lines. It is also noteworthy that three taxoids showed almost no difference in activity against drug-resistant and drug-sensitive cell lines, which are categorized as “advanced second generation taxoids“.
A simple framework to calculate the reaching definition of array references and its use in subscript array analysis

The property analysis of subscript arrays can be used to facilitate the automatic detection of parallelism in sparse/irregular programs that use indirectly accessed arrays. In order for property analysis to work, array reaching definition information is needed. In this paper, we present a framework to efficiently calculate the array reaching definition. This method is designed to handle the common program patterns in real programs. We use some available techniques as the building components, such as data dependence tests and array summary set representations and operations. Our method is more efficient as well as more flexible than the existing techniques.
Kazhdan-Lusztig polynomials and drift configurations

The coefficients of the Kazhdan–Lusztig polynomials Pv,w(q) are nonnegative integers that are upper semicontinuous relative to Bruhat order. Conjecturally, the same properties hold for h-polynomials Hv,w(q) of local rings of Schubert varieties. This suggests a parallel between the two families of polynomials. We prove our conjectures for Grassmannians, and more generally, covexillary Schubert varieties in complete flag varieties, by deriving a combinatorial formula for Hv,w(q). We introduce drift configurations to formulate a new and compatible combinatorial rule for Pv,w(q). From our rules we deduce, for these cases, the coefficient-wise inequality Pv,w(q)≼Hv,w(q).
Analytical applications of positrons

In using positrons as analytical tools the experimenter has two quite different options. The first and more obvious is to duplicate electron methods with positrons and see what differences (if any) result. The second is to exploit a unique characteristic of positrons, such as the formation and decay of the positronium atom, to study chemical composition and surface characteristics. Because positrons do not exist freely in our world, they must be obtained from radioactive sources or nuclear interactions. Source intensity has consequently been a limiting factor in experiments that attempt to duplicate electron applications. Some methods of producing and moderating positrons that have been developed here (and elsewhere) are described as well as results from studies using the sources. Surface measurements require less intense sources and yield useful data on materials such as xeolites, silica gels, graphite and alumina. Experimental apparatus, data and interpretation will be discussed.
A simple and rapid purification of commercial trypsin and chymotrypsin by reverse-phase high-performance liquid chromatography

Commercial trypsin and chymotrypsin were further purified with respective recoveries of approximately 80 and 50% of the activity in a reverse-phase high-performance liquid chromatography system using acetonitrile in dilute trifluoroacetic acid at pH 2. The purified enzymes showed single enzymatic activities toward synthetic and protein substrates. The enzymes can be rapidly purified in amounts appropriate for structural analysis of proteins.
A pathway to diphosphorus from the dissociation of photoexcited tetraphosphorus

We report a computational study of an energetically favorable pathway for the excited-state dissociation of a tetrahedral P4 molecule into two P2 molecules via the simultaneous breaking of four chemical bonds along a highly symmetric (D2d) reaction pathway. Along this pathway, a degeneracy occurs between the first excited state of P4 and the ground state of 2P2 at a lower total energy (ca. 4.7 eV) than the initial state, indicating that the initial photoexcitation provides sufficient energy for the dissociation without significant kinetic barriers. We also found that sequential dissociation of the four P–P bonds exhibits larger activation barriers thus making this a less viable dissociation pathway. Our computational investigation uncovers complicated photochemistry in elemental phosphorus, and suggests a likely mechanism for the environmentally friendly inclusion of phosphorus atoms into organic molecules.
Tropical Pacific forcing of Late-Holocene hydrologic variability in the coastal southwest United States

Abstract Change in water availability is of great concern in the coastal southwest United States (CSWUS). Reconstructing the history of water pre–1800 AD requires the use of proxy data. Lakes provide long-lived, high-resolution terrestrial archives of past hydrologic change, and their sediments contain a variety of proxies. This study presents geochemical and sedimentological data from Zaca Lake, CA (Santa Barbara County) used to reconstruct a 3000 year history of winter season moisture source (δDwax) and catchment run-off (125–2000 μm sand) at decadal resolution. Here we show that winter season moisture source and run-off are highly variable over the past 3000 years; superimposed are regime shifts between wetter or drier conditions that persist on average over multiple centuries. Moisture source and run-off do not consistently covary indicating multiple atmospheric circulation modes where wetter/drier conditions prevail. Grain-size analysis reveals two intervals of multi-century drought with less run-off that pre-date the “epic droughts” as identified by Cook et al. (2004). A well-defined wet period with more run-off is identified during the Little Ice Age. Notably, the grain size data show strong coherence with western North American percent drought area indices for the past 1000 years. As a result, our data extend the history of drought and pluvials back to 3000 calendar years BP in the CSWUS. Comparison to tropical Pacific proxies confirms the long-term relationship between El Nino and enhanced run-off in the CSWUS. Our results demonstrate the long-term importance of the tropical Pacific to the CSWUS winter season hydroclimate.