cssi/SciSciGPT-SciSciNet huggingface dataset:
The loss and depth of CO2 ice in comet nuclei

The chemical differentiation of a homogeneous, initially unmantled cometary nucleus whose composition encompasses water ice, unclathrated CO2 ice, and silicate dust, is presently simulated by an analytical model to test whether the selective sublimation of any free CO2 ice in the new comet will produce a surface layer of water ice and dust covering the undifferentiated core. The model encompasses the effects of nucleus rotation, arbitrary rotatiuon axis orientation, latitude, nucleus heat conduction, and CO2 gas outflow restriction by the water ice and dust layer.
Solid state replacement of rotating mirror cameras

Rotating mirror cameras have been the mainstay of mega-frame per second imaging for decades. There is still no electronic camera that can match a film based rotary mirror camera for the combination of frame count, speed, resolution and dynamic range. The rotary mirror cameras are predominantly used in the range of 0.1 to 100 micro-seconds per frame, for 25 to more than a hundred frames. Electron tube gated cameras dominate the sub microsecond regime but are frame count limited. Video cameras are pushing into the microsecond regime but are resolution limited by the high data rates. An all solid state architecture, dubbed 'In-situ Storage Image Sensor' or 'ISIS', by Prof. Goji Etoh has made its first appearance into the market and its evaluation is discussed. Recent work at Lawrence Livermore National Laboratory has concentrated both on evaluation of the presently available technologies and exploring the capabilities of the ISIS architecture. It is clear though there is presently no single chip camera that can simultaneously match the rotary mirror cameras, the ISIS architecture has the potential to approach their performance.
INVARIANT THEORY OF FINITE GROUP ACTIONS ON DOWN-UP ALGEBRAS

We study Artin-Schelter Gorenstein fixed subrings of some Artin-Schelter regular algebras of dimension 2 and 3 under a finite group action and prove a noncommutative version of the Kac-Watanabe and Gordeev theorem for these algebras.
Palladium-Catalyzed Carboetherification and Carboamination Reactions of γ-Hydroxy- and γ-Aminoalkenes for the Synthesis of Tetrahydrofurans and Pyrrolidines

Substituted tetrahydrofuran and pyrrolidine moieties are displayed in a wide range of interesting biologically active molecules. The Pd-catalyzed carboetherification or carboamination of γ-hydroxy- and γ-aminoalkenes is a powerful tool for the construction of these heterocycles, as it is convergent and can allow access to a variety of analogs from a single γ-hydroxy- or γ-aminoalkene starting material. This microreview describes the current state of this field.
Overtime, effort, and the propagation of business cycle shocks

Abstract This paper presents and estimates a variant of Hansen and Sargent's (1988) real business cycle model with straight time and overtime. The model presented has only one latent variable, the state of technology, yet it does a better job propagating and magnifying shocks than the labor hoarding models which incorporate unobserved effort. This model, as well as a version of Burnside, Eichenbaum, and Rebelo's (1993) labor hoarding model, is estimated using maximum likelihood. The maximum likelihood parameter estimates are compared to those using GMM.
An Algorithm for Detecting Intrinsically Knotted Graphs

We describe an algorithm that recognizes some (possibly all) intrinsically knotted (IK) graphs and can help find knotless embeddings for graphs that are not IK. The algorithm, implemented as a Mathematica program, has already been used in [Goldberg et al. 14] to greatly expand the list of known minor minimal IK graphs and to find knotless embeddings for some graphs that had previously resisted attempts to classify them as IK or non-IK.
KECK DEEP FIELDS. IV. LUMINOSITY-DEPENDENT CLUSTERING AND GALAXY DOWNSIZING IN UV-SELECTED GALAXIES AT z = 4, 3, AND 2*

We investigate the luminosity-dependent clustering of rest-frame UV-selected galaxies at z ~ 4, 3, 2.2, and 1.7 in the Keck Deep Fields, which are complete to = 27 and cover 169 arcmin2. We find that at z ~ 4 and 3, UV-bright galaxies cluster more strongly than UV-faint ones, but at z ~ 2.2 and 1.7, the UV-bright galaxies are no longer the most strongly clustered. We derive mass estimates for objects in our sample by comparing our measurements to the predicted clustering of dark matter halos in the Millennium Simulation. From these estimates, we infer relationships between halo mass and star formation rate (SFR), and find that the most massive dark matter halos in our sample host galaxies with high SFRs (M 1700 50 M ☉ yr–1) at z ~ 3 and 4, moderate SFRs (–20 < M 1700 < –19, or ~20 M ☉ yr–1) at z ~ 2.2, and lower SFRs (–19 < M 1700 < –18, or ~2 M ☉ yr–1) at z ~ 1.7. We believe our measurements may provide a new line of evidence for galaxy downsizing by extending that concept from stellar to halo mass. We also find that the objects with blue UV colors in our sample are much more strongly clustered than those with red UV colors, and we propose that this may be due to the presence of the 2175 A dust absorption bump in more massive halos, which contain the older stellar populations and dust needed to produce the feature. The relatively small area covered by the survey means that the absolute values of the correlation lengths and halo masses we derive are heavily dependent on the "integral constraint" correction, but the uniformly deep coverage across a large-redshift interval allows us to detect several important trends that are independent of this correction.
A functional on-chip pressure generator using solid chemical propellant for disposable lab-on-a-chip

This paper presents a functional on-chip pressure generator that utilizes chemical energy from a solid chemical propellant to perform fluidic delivery in applications of plastic-based disposable biochips or lab-on-a-chip systems. In this functional on-chip pressure generator, azobis-isobutyronitrile (AIBN) as the solid chemical propellant is deposited on a microheater using a screen-printing technique, which can heat the AIBN at 70 °C to produce nitrogen gas. The output pressure of nitrogen gas, generated from the solid chemical propellant, is adjustable to a desired pressure by controlling the input power of the heater. Using this chemical energy source, the generated pressure depends on the deposited amount of the solid chemical propellant and the temperature of the microheater. Experimental measurements show that this functional on-chip pressure generator can achieve around 3 000 Pa pressure when 189 mJ of energy is applied to heat the 100 µg of AIBN. This pressure can drive 50 nl of water through a microfluidic channel of 70 mm and cross-sectional area of 100 µm × 50 µm. Due to its compact size, ease of fabrication and integration, high reliability (no moving parts), biologically inert gas output along with functionality of gas generation, this pressure generator will be an excellent pressure source for handling the fluids of disposable lab-on-a-chip, biochemical analysis systems or drug delivery systems.
Low-energy, high-intensity positron beam experiments with a linac☆

Abstract Previous experiments with positrons from radionuclides have demonstrated that positron beams are a rich source of information about the surface condition of solids. We have now demonstrated the possibility of producing very intense beams at the Lawrence Livermore 100 MeV electron linac and installed an apparatus that produces a variable energy positron beam at energies between 500 eV and 20 keV with sufficient intensity to perform a variety of new positron experiments. The positron beam is pulsed with 10 ns to 3 μs duration at rates up to 1440 pulses per second, with as many as 106 positrons available per pulse. Experiments that require either pulsed or steady currents are possible in an ultrahigh vacuum environment. For the first time two-dimensional angular correlation spectra of the surface positron and positronium annihilation at a single crystal sample have been obtained for copper.
C-5 modifications in N-acetyl-neuraminic acid: scope and limitations.

Abstract Glycoconjugates containing sialic acid are involved in a large variety of biological phenomena, including cell–cell adhesion, recognition by viruses and bacteria, and oncogenesis. Therefore, they are important synthetic targets for the design of drugs and vaccines. In the last decades, different methodologies that improve yield and stereoselectivity in sialylation reactions have been investigated. This review summarizes the latest developments in the synthesis of C-5 modified sialic acid glycosyl donors and glycosyl acceptors and their application in the synthesis of α-sialosides.
Antenna Design for Mobile MIMO Systems

While significant work has been dedicated to analyzing the performance of antennas for multiple-input multiple-output (MIMO) and diversity systems, little has appeared on synthesizing optimal antennas for these systems. This paper explores optimal antenna characteristics given understanding about the average structure of the propagation environment, making the results applicable for time-varying channels created by mobile nodes or scatterer motion. Specifically, it examines optimal antenna designs for the cases where 1) the antennas reside in a fixed aperture or 2) the number of antenna elements is fixed (under fast-fading conditions with spatially correlated signals).
Skin Bleachers’ Representations of Skin Color in Jamaica

This article deals with skin bleachers’ representations of skin color and the reasons that inform their representations. A content analysis was done of the reasons the participants give for bleachi...
Preparation and Study of Tautomers Derived from 2-(2‘-Pyridyl)indole and Related Compounds

Methylation of 2-(2‘-pyridyl)indole provides the corresponding N-methylated salt that undergoes deprotonation with mild base to provide the tautomeric (E)-1-methyl-2-(2‘-indolenylidene)-1,2-dihydropyridine, whose geometry is established through a NOE experiment. Bridging at the 3,3‘-positions leads to tautomers having the opposite stereochemistry. A benzo-fused analogue exhibits similar behavior as does 2-(2‘-quinolinyl)pyrrole. The importance of the connectivity to pyridine is examined by considering three possible regioisomers, only two of which show tautomeric behavior. The tautomers show strong solvatochromic dependence and good linear behavior. The indoles absorb at shorter wavelengths and are strongly emitting while the tautomers show a strong bathochromic shift and emit only weakly; the salts exhibit intermediate behavior. NMR properties are consistent with contributions from a dipolar and uncharged resonance form while MO calculations indicate that the indole is about 40 kcal/mol more stable than ...
Simultaneous antegrade and retrograde reperfusion after cardioplegic arrest for coronary artery bypass.

Retrograde coronary sinus reperfusion with warm blood during proximal anastomoses permits completion of myocardial revascularization under a single cross-clamp application. Reperfusion with both antegrade (via arterial and vein grafts) and retrograde (via coronary sinus catheter) warm blood has raised concerns about maldistribution of perfusate or overpressurization of capillary beds. This prospective, randomized design compares post-cardioplegic myocardial recovery among patients receiving retrograde reperfusion only and patients receiving simultaneous antegradelretrograde reperfusion. Twenty-four patients were selected among all presenting as outpatients for elective coronary artery bypass (CAB). Each patient underwent CAB with cardioplegic arrest and single cross-clamp technique. During proximal anastomoses the heart was reperfused with warm blood from the cardiopul-monary bypass (CPB) circuit. Twelve received retrograde reperfusion only, and 12 received simultaneous antegradelretrograde reperfusion via an internal mammary artery (IMA) graft, all vein grafts, and the coronary sinus catheter. Vein graft perfusion was interrupted in each vein as the proximal anastomosis was performed. Myocardial recovery time (interval from initiating reperfusion until electrical and mechanical activity), cardioversion incidence, requirement for inotropic support, and Swan-Ganz hemodynamic parameters measured immediately 6 and 24 hours postoperatively were compared between groups. There were no differences between groups in age, ventricular function, number of grafts, or CPB time. Also, there were no differences in cardioversion, inotropic need, or postoperative hemodynamic performance. Myocardial recovery time was reduced in patients receiving simultaneous antegradehetrograde reperfusion (13.9 ± 7.0 vs 2.6 ± 2.1 minutes). Simultaneous reperfusion of warm blood antegrade and retrograde is not deleterious to the myocardium. More rapid recovery of myocardial function may represent a shorter period of warm ischemia but does not appear to translate to improved postoperative myocardial performance.
Twenty years of rewriting logic

Abstract Rewriting logic is a simple computational logic that can naturally express both concurrent computation and logical deduction with great generality. This paper provides a gentle, intuitive introduction to its main ideas, as well as a survey of the work that many researchers have carried out over the last twenty years in advancing: (i) its foundations; (ii) its semantic framework and logical framework uses; (iii) its language implementations and its formal tools; and (iv) its many applications to automated deduction, software and hardware specification and verification, security, real-time and cyber-physical systems, probabilistic systems, bioinformatics and chemical systems.
The application of model-referenced adaptive control to robotic manipulators

The achievement of quality dynamic performance in manipulator systems is difficult using conventional control methods because of both the inherent geometric nonlinearities of these systems and the dependence of the system dynamics on the characteristics of manipulated objects. A model-referenced adaptive control law is developed for maintaining uniformly good performance over a wide range of motions and payloads. The effectiveness of the approach is demonstrated in several simulations and the system stability as a function of input is investigated. Also developed is a 'learning signal' approach designed to minimize initial transients arising from abrupt changes in the inertial payload.
Full-information estimates of a nonlinear macroeconometric model

Abstract Results of estimating a large-scale, nonlinear macroeconometric model by full-information maximum-likelihood, nonlinear three-stage least squares, and nonlinear two-stage least squares are reported in this paper. The computation of the estimates is first discussed, and then the differences among the estimates are examined.
Dynamic kinetic resolution of epichlorohydrin via enantioselective catalytic ring opening with TMSN3. Practical synthesis of aryl oxazolidinone antibacterial agents

Abstract The dynamic kinetic resolution of racemic epichlorohydrin has been achieved via enantioselective asymmetric ring opening with TMSN3 catalyzed by the (salen)Cr(III)N3 complex 1. The resulting 3-azido-1-chloro-2-trimethylsiloxypropane product was obtained in high enantiomeric purity and incorporated into the synthesis of U-100592, a representative from a class of highly-promising aryl oxazolidinone antibacterial agents.
Regret bounds for sleeping experts and bandits

We study on-line decision problems where the set of actions that are available to the decision algorithm varies over time. With a few notable exceptions, such problems remained largely unaddressed in the literature, despite their applicability to a large number of practical problems. Departing from previous work on this "Sleeping Experts" problem, we compare algorithms against the payoff obtained by the best ordering of the actions, which is a natural benchmark for this type of problem. We study both the full-information (best expert) and partial-information (multi-armed bandit) settings and consider both stochastic and adversarial rewards models. For all settings we give algorithms achieving (almost) information-theoretically optimal regret bounds (up to a constant or a sub-logarithmic factor) with respect to the best-ordering benchmark.
Improving Bid Efficiency for Humanitarian Food Aid Procurement

Abstract The competitive bid process used by the US Department of Agriculture (USDA) to procure food supplies and transportation services for humanitarian food aid is subject to bidder gaming that can increase prices and deter competition. Additionally, suppliers and carriers are matched after bid submission, preventing synergies from coordinated planning. Given these concerns, we determine the optimal auction mechanism to minimize gaming then justify pre-bid planning between suppliers and carriers using properties of the cost distribution functions. We operationalize these changes with a uniform price auction. The improved mechanism should deter gaming, enhance bid participation, and increase delivered food aid volumes.
High school readers: A profile of above average readers and readers with learning disabilities reading expository text

Abstract This study examined above average high school readers and high school readers with learning disabilities in order to better understand the impact of twelve years of formal education on reading skills and strategy use while reading expository text. This study examined reading strategies related to knowledge construction, monitoring, and evaluating using verbal protocol analysis. Twenty-five eleventh and twelfth-grade students participated in this study, which included thirteen students with learning disabilities and twelve students with above average reading skills. The findings suggest that above average readers and students with learning disabilities share some characteristics. Both groups of students used rereading and paraphrasing as their primary mode of knowledge construction and demonstrated similar patterns in their strategy use. However, the above average readers used the strategies more effectively. The data suggest that students with learning disabilities may benefit from continued instruction at the secondary level in effective strategy use.
Changing the National Electrical Code

The National Electrical Code governs all electrical installations in industrial facilities as well as commercial and residential occupancies. Since new products and electrical technology are constantly evolving, it is necessary to periodically revise the National Electrical Code to incorporate these changes in products and applications. This paper defines the complete revision cycle and provides guidance for submitting proposals and comments to change the National Electrical Code.
OPTICAL VARIABILITY OF NARROW-LINE SEYFERT 1 GALAXIES

We present results of a broadband photometric study of the optical variability of six narrow-line Seyfert 1 (NLS1) galaxies observed at 172 epochs. We searched for microvariability on 33 nights. Strong evidence for microvariability was found only for our lowest luminosity object, NGC 4051, on one night. Weaker evidence suggests such variability on a few other nights for two other objects, but the data are not as convincing. Intranight variability in NLS1's is thus concluded to be rare and of low amplitude. We give illustrations of how variable image quality can produce spurious variability. We find that for well-studied non-NLS1's there is a spread in the amplitude of seasonal variability (i.e., in some years an active galactic nucleus [AGN] is more variable than in others). We find that the means of the variability amplitudes of non-NLS1's over several seasons vary from object to object (i.e., some AGNs are, on average, more variable than others). NLS1's also show a spread in seasonal variabilities. The best-studied NLS1, Ark 564, shows a range of amplitudes of variability from season to season that is comparable to the range found in broad-line Seyfert 1 galaxies (BLS1's), and in one season Ark 564 was as variable as the most variable non-NLS1. The seasonal amplitudes of variability for NLS1's are mostly in the lower half of the range of non-BLS1 seasonal amplitudes, but the absence of a suitable control sample makes a precise comparison difficult. However, on long timescales (weeks to years) NLS1's as a class are not more variable than non-NLS1's. The extreme variability seen in the X-rays was not seen in the optical. This has consequences for the models of AGNs in general as well as NLS1's in particular.
Genetic regulation of the androgen receptor--a study of testicular feminization in the mouse.

Abstract Testicular feminization (TFM) is an inherited disorder which is transmitted by females to half their male offspring. Affected individuals are genetic males with end organ insensitivity to androgens. As a consequence, they lack androgen dependent differentiation and present as phenotypic females. Studies on rats and mice indicate that a major tissue abnormality in testicular feminization is decreased cytosol androgen receptor activity. Deficiency of this cytosol binder could account for the lowered nuclear binding of testosterone and dihydrotestosterone in these animals. If androgen uptake and binding in the nucleus is required to initiate RNA and DNA synthesis, then the inability to concentrate androgens at the active site in the nucleus could account for the androgen insensitivity in testicular feminization. The findings in the present study support a direct correlation between the TFM gene, androgen receptor activity and androgen response.
Fluorous tin hydrides: A new family of reagents for use and reuse in radical reactions

Eight members of a new family of highly fluorinated (fluorous) tin hydrides have been synthesized and studied as reagents for radical reactions. Tin hydrides of the general formulas [Rf(CH2)n]3SnH and [Rf(CH2)n]Me2SnH have been prepared where Rf is C4F9, C6F13, C8F17, or C10F21 and n is 2 or 3. These reagents are highly soluble in fluorinated solvents, and partition coefficients between perfluorohexanes and several organic solvents have been measured. The reagents are generally useful for reductive radical reactions and hydrostannation reactions that would typically be conducted with tributyltin hydride. Stoichiometric and catalytic procedures have been developed, and both feature very easy separation of the tin products from the organic products by convenient liquid−liquid or solid−liquid extractions. The tin reagents are recovered from reactions in high yields and are routinely reused. Rate constant measurements suggest that the fluorous tin hydrides are about as reactive as (or in some cases, slightly ...
Matrix Completion with Queries

In many applications, e.g., recommender systems and traffic monitoring, the data comes in the form of a matrix that is only partially observed and low rank. A fundamental data-analysis task for these datasets is matrix completion, where the goal is to accurately infer the entries missing from the matrix. Even when the data satisfies the low-rank assumption, classical matrix-completion methods may output completions with significant error -- in that the reconstructed matrix differs significantly from the true underlying matrix. Often, this is due to the fact that the information contained in the observed entries is insufficient. In this work, we address this problem by proposing an active version of matrix completion, where queries can be made to the true underlying matrix. Subsequently, we design Order&Extend, which is the first algorithm to unify a matrix-completion approach and a querying strategy into a single algorithm. Order&Extend is able identify and alleviate insufficient information by judiciously querying a small number of additional entries. In an extensive experimental evaluation on real-world datasets, we demonstrate that our algorithm is efficient and is able to accurately reconstruct the true matrix while asking only a small number of queries.
A Colorimeter for Pyrotechnic Smokes

A tristimulus photoelectric colorimeter has been designed to measure the chromaticities of pyrotechnic smokes having highly saturated colors. To obtain a compact housing for three multiplier phototubes, “head-on” type (RCA 5819) phototubes are used. For high sensitivity and stability the photometric units are three Photovolt Multiplier Photometers, Model 520-M. To minimize edge effects and rear wall reflection, the smoke chamber was designed as a 36-inch cube. The chamber is illuminated by four 150-watt flood lamps placed to yield uniform illumination on the viewing window. Three filters were designed to approximate the daylight CIE standard observer functions for the source-filter-phototube combinations of the instrument. As the CIE y¯ and z¯ functions are unimodal, little difficulty was encountered in designing the filters to approximate these functions. The CIE x¯ function, which is bimodal, required a divided filter to approximate its two lobes. The filter constructed was composed of two sectors, one approximating the “blue lobe,” the other approximating the “red lobe,” of the x¯ function. Satisfactory results have been obtained with this colorimeter using Munsell papers as standards.
Schema analysis for database restructuring

The problem of generalized restructuring of databases has been addressed with two limitations: first, it is assumed that the restructuring user is able to describe the source and target databases in terms of the implicit data model of a particular methodology; second, the restructuring user is faced with the task of judging the scope and applicability of the defined types of restructuring to his database implementation and then of actually specifying his restructuring needs by translating them into the restructuring operations on a foreign data model. A certain amount of analysis of the logical and physical structure of databases must be performed, and the basic ingredients for such an analysis are developed here. The distinction between hierarchical and nonhierarchical data relationships is discussed, and a classification for database schemata is proposed. Examples are given to illustrate how these schemata arise in the conventional hierarchical and network systems. Application of the schema analysis methodology to restructuring specification is also discussed. An example is presented to illustrate the different implications of restructuring three seemingly identical database structures.
Elliptic grid generation

Various types of generating systems for boundary-conforming coordinate systems based on the numerical solution of systems of elliptic partial differential equations are discussed. Particular emphasis is given to the determination of functions in these equations which control the distribution of the curvilinear coordinate lines in the field.
Snapshots of hadrons or the story of how the vacuum medium determines the properties of the classical mesons which are produced, live and die in the QCD vacuum

1. QCD Sum Rules: 20 Years After; 2. QCD Vacuum and Basics of the SVZ Method: 2.1 General ideas; 2.2. Getting started/Playing with toy models; 3. Vacuum Condensates; 4. Rho Meson in QCD; 5. Basic Theoretical Instrument -- Wilson's OPE; 6. Practical Version of OPE; 7. Low Energy Theorems; 8. Are All Hadrons Alike? 9. Ecological Niche; 10. New Developments: 10.1 Light-cone sum rules; 10.2 Heavy flavor sum rules; 11. Sum Rules and Lattices; 12. Vacuum Fluctuations are Subtle Creatures; 13. Instead of Conclusions.
Measuring proton energies and fluxes using EIT (SOHO) CCD areas outside the solar disk images

An indirect proton flux measuring tool based on discrimination of the energy deposited by protons in 128 × 128 pixel EIT CCD areas outside the solar disk images is presented. Single pixel intensity events are converted into proton incident energy flux using modeled energy deposition curves for angles of incidence ±60° in four EIT spatial areas with different proton stopping power. The extracted proton flux is corrected for both the loss of one-pixel events in the range of angles of incidence as well as for the contribution to the single pixel events resulting from scattered middle-energy protons (low-energy or high-energy particles are stopped by the EIT components or pass through them, accordingly). A simple geometrical approach was found and applied to correct for a non-unique relation between the proton-associated CCD output signal and the incident proton energy. With this geometrical approximation four unique proton incident energy ranges were determined as 45–49, 145–154, 297–335, and 390–440 MeV. The indirect proton flux measuring tool has been tested by comparing Solar Energetic Particles (SEP) flux temporal profiles extracted from the EIT CCD frames and downloaded from the GOES database for the Bastille Day (BD) of 2000 July 14 and the more recent 2005 January 20 events. The SEP flux temporal profiles and proton spectra extracted from the EIT in the relatively narrow energy ranges between 45 and 440 MeV reported here are consistent with the related GOES profiles. The four additional EIT extracted ranges provide higher energy resolution of the SEP data. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
ABSENCE OF PHOSPHATIDYLGLYCEROL IN AMNIOTIC FLUID OF BABOONS AT TERM

89 samples of amniotic fluid were obtained from 46 pregnant baboons at 91 to 176 days of gestation (term = 180 days). In 8 baboons delivered by cesarean section at 174-176 days of gestation, the entire amniotic fluid contents of the uterus were aspirated and lung lavage was performed within 1 hour of birth. Surfactant was purified from these 8 amniotic fluids and products of lung lavage by differential and density-gradient centrifugation. Lecithin/sphingomyelin ratios ranged from 0 to 2.41. Mean (±SD) L/S ratio at term was significantly higher than before term (0.77±0.55 vs 0.28±0.25, p<0.001). Of 12 samples obtained after 170 days of pregnancy, only 6 had L/S ratios greater than 1 and only 1 had a ratio in excess of 2. The relation between L/S ratios and gestational maturity was best described as a second order polynomial (r=0.63, p<0.001). Phosphatidylglycerol (PG) was detected in none of the amniotic fluid samples. Of the 8 surfactants purified from amniotic fluid at term, none contained detectable amounts of PG. Yet, 6 of 7 surfactants purified from products of lung lavage did contain PG. These data suggest 3 possibilities: (1) baboon fetuses make no PG; (2) PG is present in amniotic fluid, but in concentrations too low to be detected; or (3) PG is present in the lungs but is not excreted into amniotic fluid. The third explanation appears to be most likely.
Water Masers associated with Star Formation in the Antennae Galaxies

We present Very Large Array (VLA) observations with 80 mas resolution ({approx}9 pc) of the recently discovered Galactic-analog (GA)-H{sub 2}O masers in the Antennae interacting galaxies (NGC 4038/NGC 4039; Arp244). Three regions of water maser emission are detected: two in the 'interaction region' (IAR) and the third {approx}5.''6 ({approx_gt}600 pc) west of the NGC 4039 nucleus. The isotropic H{sub 2}O maser luminosities range from 1.3 to 7.7 L{sub sun}. All three maser regions are mostly obscured in the optical/near-infrared continuum, and are coincident with massive CO-identified molecular clouds. The H{sub 2}O maser velocities are in excellent agreement with those of the molecular gas. We also present archival VLA 3.6 cm data with {approx}0.''28 ({approx}30 pc) and {approx}0.''8 ({approx}90 pc) resolution toward the maser locations. All three maser regions are coincident with compact 3.6 cm radio continuum emission, and two are dominated by thermal ionized gas, suggesting the presence of natal super star clusters containing the equivalent of a few thousand O stars. We also present detailed comparisons between the radio data and existing Hubble Space Telescope Advanced Camera for Surveys (optical) and NICMOS (near-IR) data and find that both maser regions in the IAR are also associated with Pa{alpha} emissionmore » and neither source is detected shortward of 2 {mu}m. These results highlight the potential of using GA-H{sub 2}O masers to pinpoint sites of young super star cluster formation with exquisite angular resolution.« less
An investigation of chaotic Kolmogorov flows

A two‐dimensional flow governed by the incompressible Navier–Stokes equations with a steady spatially periodic forcing (known as the Kolmogorov flow) is numerically simulated. The behavior of the flow and its transition states as the Reynolds number Re varies is investigated in detail, as well as a number of the flow features. A sequence of bifurcations is shown to take place in the flow as Re varied. Two main regimes of the flow have been observed: small and large scale structure regimes corresponding to different ranges of Re. Each of the regimes includes a number of periodic, chaotic, and relaminarization windows. In addition, each range contains a chaotic window with nonunique chaotic attractors. Spatially disordered, but temporally steady states have been discovered in the large scale structure regime. Features of the diverse cases are displayed in terms of the temporal power spectrum, Poincare sections and, where possible, Lyapunov exponents and Lyapunov dimension.
Some properties of O(32) superstrings

Some properties of the anomaly-free O(32) superstring theory recently discovered by Green and Schwarz are discussed. With proper choice of ground state, the theory leads in four dimensions to an SU(5) theory with any desired number of standard generations (and no exotic or mirror fermions). It predicts axions and stable Nielsen-Olesen vortex lines. It can be consistently compactified only if certain topological conditions are imposed.
Enhanced Mechanical Properties of Smart Polymer-Matrix Hybrid Composite by Shape Memory Effect

New smart hybrid composite with TiNi shape memory alloy (SMA) fiber as reinforcement is designed to be composed of TiNi fiber and carbon/epoxy (CFRP) composite. One-dimensional composite modeling is utilized to evaluate residual stresses of the smart composite generated by shape memory effects. The modeling indicated that the tensile strength of TiNi/CFRP composite is improved due to the shape memory effect of TiNi fiber for both parallel and perpendicular configurations of TiNi fiber with respect to the direction of carbon fiber. Modeling also shows the tensile strength is increased with increasing both volume fraction of TiNi fiber and amount of prestrain.
An Excursion Set Model of the Cosmic Web: the Abundance of Sheets, Filaments And Halos

We discuss an analytic approach for modeling structure formation in sheets, filaments, and knots. This is accomplished by combining models of triaxial collapse with the excursion set approach: sheets are defined as objects that have collapsed along only one axis, filaments have collapsed along two axes, and halos are objects in which triaxial collapse is complete. In the simplest version of this approach, which we develop here, large-scale structure shows a clear hierarchy of morphologies: the mass in large-scale sheets is partitioned up among lower mass filaments, which themselves are made up of still lower mass halos. Our approach provides analytic estimates of the mass fraction in sheets, filaments, and halos and its evolution, for any background cosmological model and any initial fluctuation spectrum. In the currently popular ΛCDM model, our analysis suggests that more than 99% of the cosmic mass is in sheets, and 72% in filaments, with mass larger than 1010 M☉ at the present time. For halos, this number is only 46%. Our approach also provides analytic estimates of how halo abundances at any given time correlate with the morphology of the surrounding large-scale structure and how halo evolution correlates with the morphology of large-scale structure.
Dynamic properties of tilting-pad journal bearings : Experimental and theoretical investigation of frequency effects due to pivot flexibility

Tilting-pad journal bearings (TPJBs) dominate as rotor supports in high-speed rotating machinery. The paper analyzes frequency effects on the TPJB’s stiffness and damping characteristics based on experimental and theoretical investigations. The experimental investigation has been carried out on a five pad tilting-pad journal bearing of 98mm in diameter. Time domain and multifrequency excitation has been used to evaluate the dynamic coefficients. The calculated results have been obtained from a three-dimensional computer model of TPJB, which accounts for thermal effects, turbulent oil flow, and elastic effects, including that of pad flexibility. The analyzes of the TPJB’s stiffness and damping properties showed that the frequency effects on the bearing dynamic properties depend on the operating conditions and bearing design. It has been concluded that the pad inertia and pivot flexibility are behind the variations of the stiffness and damping properties with frequency of excitation.
Branes and instantons intersecting at angles

We study in detail the system of D6 branes and euclidean D2-brane instantons intersecting at angles in type IIA string theory. We find that in the absence of orientifolds the system does not contribute to the low energy superpotential, in agreement with expectations based on effective field theory arguments. We also comment on the implications of our results for dual string theory pictures.
Cross-display-technology video motion measurement tools

High performance video places severe demands on playback system and display device resources. Motion playback errors such as irregular motion playback and image breakup are common, making accurate measurement of motion critically important for device selection and system tuning to ensure the desired viewing experience. Direct observation of the actual displayed image (screen capture) is the only way to perform a complete end-to-end system test that accounts for all possible sources of motion errors, including original video capture, compression/decompression, playback system performance, and display device operation. Unfortunately for the development of measurement techniques, the fundamentally different ways that different display technologies present imagery can easily confound sensitive measurement techniques, producing measured playback performance differences across multiple display technologies such as LCD (liquid crystal display), plasma, CRT (cathode ray tube), and DMD (digital micromirror device) that are disproportionately large compared to the actual differences (if any) seen by a human viewer. Cross technology measurement tools are necessary to ensure the validity of measures across multiple technologies. The methods being used include a combination of test materials (both selected live video clips and synthetic clips), capture technique (including control of capture rate, triggering, and timestamping), and analysis. This paper describes these methods, then gives several illustrative examples of the use of these methods by the project. The NIST Motion Image Quality Measurement project uses a combination of quantitative measures and subjective analysis to evaluate motion imagery and to identify the factors that determine overall performance. The NIST project has conducted tests to measure (1) perceived image quality and (2) motion image interpretability, as a function of factors including compression, video motion and other scene content, playback system performance, and frame rate. Tests have been conducted using a variety of playback systems with different levels of performance, and using a variety of display technologies.
On the Lack of X-Ray Iron Line Reverberation in MCG –6-30-15: Implications for the Black Hole Mass and Accretion Disk Structure

We use the method of Press, Rybicki, & Hewitt to search for time lags and time leads between different energy bands of the RXTE data for MCG -6-30-15. We tailor our search in order to probe any reverberation signatures of the fluorescent iron Kα line that is thought to arise from the inner regions of the black hole accretion disk. In essence, an optimal reconstruction algorithm is applied to the continuum band (2-4 keV) light curve that smooths out noise and interpolates across the data gaps. The reconstructed continuum band light curve can then be folded through trial transfer functions in an attempt to find lags or leads between the continuum band and the iron line band (5-7 keV). We find reduced fractional variability in the line band. The spectral analysis of Lee et al. reveals this to be due to a combination of an apparently constant iron line flux (at least on timescales of few × 104 s) and flux-correlated changes in the photon index. We also find no evidence for iron line reverberation and exclude reverberation delays in the range 0.5-50 ks. This extends the conclusions of Lee et al. and suggests that the iron line flux remains constant on timescales as short as 0.5 ks. The large black hole mass (>108 M☉) naively suggested by the constancy of the iron line flux is rejected on other grounds. We suggest that the black hole in MCG -6-30-15 has a mass of MBH ~ 106-107 M☉ and that changes in the ionization state of the disk may produce the puzzling spectral variability. Finally, it is found that the 8-15 keV band lags the 2-4 keV band by 50-100 s. This result is used to place constraints on the size and geometry of the Comptonizing medium responsible for the hard X-ray power law in this AGN.
Vacuum pumping requirement considerations for future fusion devices

Abstract The vacuum pumping requirements for a fusion device are dictated by a number of factors, including the materials used in construction of the device, the cleaning and conditioning techniques implemented, the operating conditions and device temperature, the plasma characteristics, and the fuel gases and impurities retained and released by the plasma-facing components (PFCs). In an attempt to derive guidelines for determining the vacuum pumping requirements of a generic fusion device, a study was undertaken to examine the vacuum pumping capabilities of existing large fusion devices, to review the cleaning and conditioning techniques now in use, and to catalog pertinent vacuum equipment that is now available or anticipated soon. In a survey of six large fusion devices [ASDEX, DIII-D, the Joint European Torus (JET), JT-60, the Tokamak Fusion Test Reactor (TFTR), Tore Supra], information was collected on PFC materials, cleaning and conditioning techniques, device operating temperatures, and vacuum pumping system characteristics and on the surface conditions and partial pressures necessary to achieve high-purity plasma discharges in each device. The results of the survey are reviewed to determine how the various factors affect vacuum pumping requirements. The use of tritium in future fusion devices is expected to create a new set of problems for the vacuum pumping systems of these devices. These problems are addressed, and some possible solutions for the pumping and gas handling systems are identified. New vacuum equipment is under development, and the fusion community is in a position to influence its direction and emphasis. Information gained in studies of this type should be brought to bear on the development process to ensure that vacuum equipment will be available to meet the needs of future fusion devices.
Enantioselective synthesis of (+)-anatoxin-a via enyne metathesis

Abstract A concise synthesis of the potent n AChR agonist (+)-anatoxin-a ( 1 ) has been completed by a series of nine chemical operations and in 27% overall yield from commercially available d -methyl pyroglutamate ( 12 ). The strategy featured the application of a new protocol for the diastereoselective synthesis of cis -2,5-disubstituted pyrrolidines bearing unsaturated side chains and an intramolecular enyne metathesis to provide the bridged bicyclic framework of 1 . Thus, d -methyl pyroglutamate ( 12 ) was converted in five steps to 32 , which underwent facile enyne metathesis to deliver the bicyclic diene 33 . Selective oxidative cleavage of the less substituted carbon–carbon double bond in 33 followed by deprotection furnished (+)-anatoxin-a ( 1 ).
The Forgotten Threat: Private Policing and the State

What do Disneyland, the Abu Ghraib U.S. military prison, the Mall of America, and the Y-12 nuclear security complex in Oak Ridge, Tennessee have in common? They have wildly different purposes, but they share a common characteristic as employers of private police. This answer-indicative of the prevalence and numbers of private police today-would have struck the nineteenth-century observer as evidence of a gross failure by the state. Yet that reaction, in turn, would seem odd to us. Vocal support of private police can be found among public police chiefs, lawmakers, and even President Bush. What kinds of criticisms were once leveled at private police by public officials? How did one attitude, deeply skeptical of private police, evolve into another that sees heavy reliance upon private policing as beneficial, or at least benign? Here, I take a fresh look at the dynamics of that change, and by doing so, restore to their proper place fundamental questions about the use of police who are privately financed and organized in a democratic society. These questions, and the violent history that midwived them, have been largely and undeservedly forgotten by the legal literature. Using this historical perspective, I examine the shifting status of private policing: first, by examining the history of public criticism directed against them; second, by recounting the partnership model that first gained a foothold in studies sponsored by the federal government in the 1970s and 1980s; and third, by questioning the meaning and intentions behind the idea of partnership advanced today.
Hydrocarbons via photosynthesis

Abstract Photosynthesis is examined as a possible annually renewable resource for material and energy. The production of fermentation alcohol from sugar cane as a major component of materials for chemical feedstocks is examined as well as the direct photosynthetic production of hydrocarbons from known plant sources. Experiments are underway to analyze the hydrocarbons from Euphorbias, Asclepias, and other hydrocarbon-containing plants with a view toward determining their various chemical components. In addition, experimental sowings of plants of this type have begun to produce data on which species would be the most successful. Work is also underway on the development of chemical process techniques for the extraction of plant materials after harvesting. In addition, efforts are underway to construct synthetic systems on the basis of our knowledge of the natural photosynthetic processes. These systems could be used to produce fuel, fertilizer, and power. As a result of studies of the natural quantum conversion process in green plants, we can envisage several photoelectron transfer processes, some of which have already been demonstrated in synthetic systems. Methods of constructing systems of this type and the principles of their use are described.
Cosmology in the Randall–Sundrum brane world scenario

Abstract The cosmology of the Randall–Sundrum scenario for a positive tension brane in a 5-D Universe with localized gravity has been studied extensively recently. Here we extend it to more general situations. We consider the time-dependent situation where the two sides of the brane are different AdS/Schwarzschild spaces. We show that the expansion rate in these models during inflation could be larger than in brane worlds with compactified extra dimensions of fixed size. The enhanced expansion rate could lead to the production of density perturbations of substantially larger amplitude.