cssi/SciSciGPT-SciSciNet huggingface dataset:
Diel Variations in Optical Properties of Micromonas pusilla, A prasinophyte

Micromonas pusilla (Butcher) Manton et Parke, a marine prasinophyte, was used to investigate how cell growth and division affect optical properties of phytoplankton over the light:dark cycle. Measurements were made of cell size and concentration, attenuation and absorption coefficients, flow cytometric forward and side light scattering and chl fluorescence, and chl and carbon content. The refractive index was derived from observations and Mie scattering theory. Diel variations occurred, with cells increasing in size, light scattering, and carbon content during daytime photosynthesis and decreasing during nighttime division. Cells averaged 1.6 � m in diameter and exhibited phased division, with 1.3 divisions per day. Scattering changes resulted primarily from changes in cell size and not refractive index; absorption changes were consistent with a negligible package effect. Measurements over the diel cycle suggest that in M. pusilla carbon-specific attenuation varies with cell size, and this relationship appears to extend to other phytoplankton species. Because M. pusilla is one of the smallest eukaryotic phytoplankton and belongs to a common marine genus, these results will be useful for interpreting in situ light scattering variation. The relationship between forward light scattering (FLS) and volume over the diel cycle for M. pusilla was similar to that determined for a variety of phytoplankton species over a large size range. We propose a method to estimate cellular carbon content directly from FLS, which will improve our estimates of the contribution of different phytoplankton groups to productivity and total carbon content in the oceans.
USING INVESTMENT DATA TO ASSESS THE IMPORTANCE OF PRICE MISMEASUREMENT

This paper presents a new approach to assess the role of price mismeasurement in the productivity slowdown. I invert the firm’s investment decision to identify the embodied and disembodied components of productivity growth. With a CobbDouglas production function, output price mismeasurement only should affect the latter. Contrary to the mismeasurement hypothesis, I find that in the Post-War period, disembodied productivity grew faster in the hard-to-measure than in the non-manufacturing easy-to-measure sectors, and that disembodied productivity slowed down less in the hard-to-measure than in the easy-to-measure sectors since the 70’s. These results holda fortiori when capital and labor are complements.
Acoustic to seismic ground excitation using time reversal

The detection of land mines using acoustic and seismic excitation is problematic due to the small amplitude of vibration that can be induced in the soil. Increasing this level reduces the requirement on a sensor"s noise floor and may be useful for nonlinear detection. For these experiments, an array of loudspeakers broadcast orthogonal noise signals to excite ground vibrations. A contacting geophone measures the system"s vibration response to all signals. We then correlate an excitation signal with the measured vibration response to approximate the system impulse response between a loudspeaker and the geophone. Time reversing the impulse response generates a pre-filter for each loudspeaker. Subsequent signals transmitted through the pre-filter and loudspeaker tend to be temporally focused at the receive location as well as greater in amplitude. Results compare vibration amplitude with and without the time reversal process for spatial locations near the mine.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Algebraic topology of Calabi–Yau threefolds in toric varieties

We compute the integral homology (including torsion), the topological K‐theory, and the Hodge structure on cohomology of Calabi‐Yau threefold hypersurfaces and semiample complete intersections in toric varieties associated with maximal projective triangulations of reflexive polytopes. The methods are purely topological. 14J32; 32Q25 One of the most fruitful sources of Calabi‐Yau threefolds is hypersurfaces, or more generally complete intersections, in toric varieties. This is especially true since there is a proposal for the mirror of any such Calabi‐Yau threefold. Usually the toric varieties associated to convex lattice polytopes are singular, causing the Calabi‐Yau threefolds in them also to be singular, so that to get smooth Calabi‐Yau threefolds we must resolve the ambient singularities and take the preimage in the resolution of the singular Calabi‐Yau threefold. This can be done torically by the combinatorial device of taking a triangulation of the boundary of the convex lattice polytope defining the toric variety where the vertices of the triangulation are exactly the lattice points contained in the boundary of the polytope. In general, there will be many such triangulations of a given lattice polytope, leading to different ambient resolutions producing different families of Calabi‐Yau threefolds associated with the original toric variety. In spite of the existence of many different such resolutions of a given singular object, there are lattice-theoretic formulas for the Hodge numbers of these resolutions expressed in terms of the lattice polytope and its polar. Thus, the Hodge numbers of all the different resolutions coming from different triangulations are the same. The proofs of these combinatorial formulas rely on the Griffiths‐Dwork method of computing Hodge numbers using residues of meromorphic differentials on the complement of the Calabi‐Yau threefolds in the toric ambient space (Batyrev and Borisov [1; 2]). The same methods were used in (Mavlyutov [12]) to describe the Hodge components in complex cohomology explicitly. In this paper we study the resolution process from a more topological point of view. In the topological study of these objects, one treats both complete intersections and
SYSTEMATIC ERRORS IN ELEMENTAL ABUNDANCES DERIVED FROM NEBULAR SPECTRA

We examine the global accuracy of the commonly used multizone approach to inferring elemental abundances from nebular spectra. We use a large model grid of constant-density models to construct "ionization correction factors" (iCF's) for several ions with bright optical lines. The emission lines from the model suite were analyzed as coming from a two-zone nebula, with temperatures and densities based on diagnostic line ratios. These were used to infer the ionic abundances responsible for the emission lines, to which the iCF's were applied. The procedure was also applied to model grids simulating blister-type H II regions, as well as individual dense knots. Comparison of the model elemental abundances to those inferred from their line emission show large deviations with respect to the demonstrated accuracy of the analysis procedure; in addition, the inaccuracies of the three models follow significantly different trends, defeating any secondary correction appropriate for arbitrary nebulae. We thus strongly favor other methods for determining abundances from observations; e.g., direct modeling of photoionized nebulae or their small-scale structures.
Compact binary coalescences in the band of ground-based gravitational-wave detectors

As the ground-based gravitational-wave telescopes LIGO, Virgo and GEO 600 approach the era of first detections, we review the current knowledge of the coalescence rates and the mass and spin distributions of merging neutron-star and black-hole binaries. We emphasize the bi-directional connection between gravitational-wave astronomy and conventional astrophysics. Astrophysical input will make possible informed decisions about optimal detector configurations and search techniques. Meanwhile, rate upper limits, detected merger rates and the distribution of masses and spins measured by gravitational-wave searches will constrain astrophysical parameters through comparisons with astrophysical models. Future developments necessary to the success of gravitational-wave astronomy are discussed.
New solutions for the planetary dynamics in HD160691 using a Newtonian model and latest data

In this letter, we present several new three- and four-planet solutions based on the most current available radial velocity data for HD160691 (μAra). These solutions are optimized using the Planetary Orbit Fitting Process (POFP) which is programmed and executed in matlab. POFP is based on a full integration of the system's multiple-body Newtonian equations of motion and on a multilevel optimization utilizing a variety of algorithms. The POFP solutions are presented in the context of the Keplerian-based solutions already appearing in the literature which we have reproduced here for comparison. The different solutions and their properties are compared over all data sets separately and combined. The new solutions do not seem to exhibit instabilities, and are both co-planar and three-dimensional. We also provide a comparative prediction of the published and new solutions showing their diversion in the near future. In the short term, this projection will allow to choose between the variety of solutions as further observations are made.
The Sloan Bright Arcs Survey: Six Strongly Lensed Galaxies at z = 0.4-1.4

We present new results of our program to systematically search for strongly lensed galaxies in the Sloan Digital Sky Survey (SDSS) imaging data. In this study six strong lens systems are presented which we have confirmed with followup spectroscopy and imaging using the 3.5m telescope at the Apache Point Observatory. Preliminary mass models indicate that the lenses are group-scale systems with velocity dispersions ranging from 466?878 km s{sup -1} at z = 0.17-0.45 which are strongly lensing source galaxies at z = 0.4-1.4. Galaxy groups are a relatively new mass scale just beginning to be probed with strong lensing. Our sample of lenses roughly doubles the confirmed number of group-scale lenses in the SDSS and complements ongoing strong lens searches in other imaging surveys such as the CFHTLS (Cabanac et al. 2007). As our arcs were discovered in the SDSS imaging data they are all bright (r {approx_equal} 22), making them ideally suited for detailed follow-up studies.
The nonperturbative gauge coupling of N=2 supersymmetric theories

Abstract We argue that the topology of the quantum coupling space and the low energy effective action on the Coulomb branch of scale invariant N =2 SU ( n ) gauge theories pick out a preferred nonperturbative definition of the gauge coupling up to non-singular holomorphic reparametrizations.
A multimonopole solution in string theory

Abstract A multimonopole solution in Yang-Mills field theory is obtained by a modification of the 't Hooft ansatz for a four-dimensional instanton. Although this solution has divergent action near each source, it can be used to construct a finite action multimonopole solution of heterotic string theory, in which the divergences from the Yang-Mills sector are precisely cancelled by those from the gravity sector. We argue that this solution is exact to all orders in a α'.
Minimally invasive esophagectomy for Barrett's esophagus with high-grade dysplasia.

Abstract Background: Barrett’s esophagus with high-grade dysplasia (BE/HGD) is associated with invasive carcinoma in 30% to 70% of cases. Esophagectomy is the treatment of choice for patients with BE/HGD but esophagectomy can be associated with high morbidity and mortality. The aim of our study was to report our preliminary experience in applying minimally invasive surgical techniques to esophagectomy for BE/HGD. Methods: From August 1996 to February 1999, 12 consecutive patients underwent minimally invasive esophagectomy for biopsy-proven BE/HGD. Our consort consisted of 7 men and 5 women; average age was 64 years (range, 40-78 years). All patients underwent a complete laparoscopic or combined laparoscopic and thoracoscopic resection of the esophagus with cervical anastomosis. Results: Mean operative time was 7.8 ± 2.1 hours, mean intensive care unit stay was 2.6 ± 2.2 days, and mean length of hospital stay was 8.3 ± 4.7 days. Five patients (42%) had carcinoma in situ or carcinoma identified on pathologic specimen. Analyses of all resected lymph nodes in the 12 patients were negative for metastatic disease. There were 6 major complications in 5 patients: 1 patient had a small bowel perforation requiring operative repair, 2 patients needed prolonged ventilatory support for respiratory insufficiency, and 3 patients had delayed gastric emptying requiring revision of the pyloromyotomy. The single minor complication in this series was a jejunostomy tube-site infection. There were no conversions to laparotomy or thoracotomy. All patients were alive and free of metastatic disease at a mean follow-up of 12.6 months. Conclusions: Minimally invasive esophagectomy is a feasible and safe alternative to conventional open esophagectomy for patients with BE/HGD. (Surgery 2000;127:284-90.)
Pittsburgh Diabetes Mellitus Study: Studies on the Etiology of Insulin‐Dependent Diabetes Mellitus with Special Reference to Viral Infections

The etiology of IDDM remains incompletely understood, with genetic predisposition, autoimmune destruction of the beta cells and viral infections interacting to produce disease. It appear that the underlying genetic defect is an alteration in cellular and/or humorally-mediated immunological responsiveness. There are at least two (and probably more) genetically determined defects identified by HLA B-8 (DR3) and B- 15 (DR4). A number of viruses have been implicated in IDDM causation, including Coxsackie, mumps, rubella, Epstein-Barr, hepatitis and influenza viruses, but in only a few cases is viral etiology fully documented. Viral infections may trigger autoimmunity. Alterations in immunoglobulin concentration, particularly IgA deficiency, have been reported by several investigators. Collaborative prospective studies of individuals at high risk for the development of IDDM (siblings with HLA identical to the index case) are essential in the future study of IDDM etiology.
Rapid Access to Complex Molecular Architectures via o-Azaquinones.

A multitude of natural product like molecules such as 2 and 3 can be readily obtained from hydroxyketoamide 1. The versatile 1 is derived, via the intermediate o-azaquinone 4, from the Dess-Martin periodinane oxidation of the corresponding anilide.
Fabrication and Use of Nanometer-Sized Electrodes in Electrochemistry

Electrodes with electrochemical dimensions as small as 10 angstroms have been fabricated and used for electrochemical studies. These nanometer-scale electrodes have enabled the measurement of electron-transfer rate constants, k_(het), that are two orders of magnitude faster than k_(het) values accessible with any other electrochemical method.
Precise Timing of the X-ray Pulsar 1E 1207.4–5209: A Steady Neutron Star Weakly Magnetized at Birth

We analyze all X-ray timing data on 1E 1207.4-5209 in supernova remnant PKS 1209-51/52 gathered from 1993-2005 and find a highly stable rotation with P = 424.130749(4) ms and = (6.6 ± 9.0) × 10-17 (1 σ errors). This refutes previous claims of large timing irregularities in these data. In the dipole spin-down formalism, the 2 σ upper limit on implies a spin-down luminosity 27 Myr. This τc exceeds the remnant age by 3 orders of magnitude, requiring that the pulsar was born spinning at its present period. The X-ray luminosity of 1E 1207.4-5209, Lbol ≈ 2 × 1033(d/2 kpc)2 ergs s-1, exceeds its , implying that Lbol derives from residual cooling and perhaps partly from accretion of supernova debris. The upper limit on Bp is small enough to favor the electron-cyclotron model for at least one of the prominent absorption lines in its soft X-ray spectrum. This is the second demonstrable case of a pulsar born spinning slowly and with a weak B-field, after PSR J1852+0040 in Kesteven 79. We suggest that these properties define the class of central compact objects.
Lost in transition: Illicit substance use and services receipt among at-risk youth in the child welfare system

Abstract This study examined the use of mental health and substance abuse services among adolescents in the child welfare system (CWS) who reported use of illicit substances. 1004 adolescents age 11–15 years at baseline were followed for 5–7 years, over five waves of data collection. Shortly after the investigation for maltreatment (baseline), 69.1% of youths using illicit substances received mental health and/or substance abuse outpatient specialty services. By the last follow-up, during the transition to adulthood, only 21.5% of young adults using illicit substances received outpatient specialty services. Youth who used illicit substances were more likely to receive outpatient and inpatient specialty services than non-users at the time of contact with the CWS (mostly baseline), but this difference faded over the follow-up period. By 5–7 years follow-up, there was no significant difference in specialty services receipt for illicit substances users versus non-users. Predictors of outpatient service use at most waves were having Medicaid, mental health needs, and having recently seen a school counselor or primary care physician. Among illicit substance users transitioning to adulthood, African American youths were less likely to receive outpatient specialty services than White youths. These findings reveal a need for more attention to illicit substances use among youth in the CWS, better cross agency integration, and special attention to the needs of transition-age youth to better connect them with services as they age out of the CWS.
A Search for Radio Gravitational Lenses, Using the Sloan Digital Sky Survey and the Very Large Array

We report on a novel search for radio gravitational lenses. Using the Very Large Array, we imaged 10 candidates with both dual redshifts in Sloan Digital Sky Survey spectra and 1.4 GHz radio flux ≥2 mJy in the FIRST survey. The VLA maps show that in each case the radio emission is associated with the foreground galaxy rather than being lensed emission from the background galaxy, although at least four of our targets are strong lenses at optical wavelengths. These SDSS dual-redshift systems do not have lensed radio emission at the sensitivity of current radio surveys.
Mispredicting Others’ Valuations: Self-Other Difference in the Context of Endowment

The authors argue that people systematically fail to predict how much others in the same role (i.e., owner or buyer) value an object due to self-other differences in valuation arising from intra-role empathy gaps. Across five studies in an endowment context, owners consistently underestimate the average selling price demanded by other owners, whereas buyers overestimate the average purchase price offered by other buyers by over 20%. Participants, however, make more accurate predictions of the valuation of others in the same role when either (a) an external influence (i.e., similarity priming) or (b) their high cognitive and emotional tendency to connect with others leads to a reduction in empathy gaps. Implications for theory and practice are discussed.
Microwave-assisted reduction of carbonyl compounds in solid state using sodium borohydride supported on alumina

Abstract A manipulatively simple and rapid method for the reduction of carbonyl compounds is described that is conducted under solventless ‘dry’ conditions using NaBH 4 -Alumina and microwave irradiation.
Single-Facet Teardrop Laser With Matched-Bends Design

The matched-bends criterion, a method for effectively reducing the straight-bend-straight transition loss in planar optical waveguides, is applied to design a single-facet teardrop laser utilizing an on-chip loop mirror reflector. Simulations of a matched-bends teardrop reflector show a great improvement in power reflectance (97%) over unmatched-bends designs (10%). The teardrop laser is fabricated by deep etching and nonselective sidewall oxidation of an 808-nm AlGaAs/InAlGaAs/GaAs heterostructure. The resulting high-index-contrast ridge-waveguide laser exhibits a low-threshold current of 43 mA, a high slope efficiency of 0.465 W/A, and a single spectral lasing mode with a side-mode suppression ratio of 24 dB. Simulations are presented to demonstrate that the matched-bends design can be scaled geometrically to reduce the area occupied by the teardrop bend reflector by a factor of 677.
Research in structures and materials for future space transportation systems - An overview

The paper provides a review of some of the advances of the past decade in structures and materials that have application to future space transportation systems. The paper concentrates on metallic thermal protection systems and structures which could provide the structural efficiency, reliability, and durability dictated by future space utilization requirements. The need for completely reusable, on-board cryogenic fuel tanks is cited as the most challenging technical opportunity and potential thermostructural concepts for tanks are identified. Other critical areas needing technology advances are discussed. Finally, the unique research opportunities offered by the Shuttle Orbiter experiments program for testing structures and thermal protection systems are explored.
Sectarian Rebellions in Post-Transition Nigeria Compared

The Boko Haram, a radical Islamic group based in north-east Nigeria, has killed over 1,000 people since mid-2011. This article explores the historical origins and structural drivers of Boko Haram and puts them into context. It argues that the Nigerian government's coercive response to Boko Haram has perpetuated a cycle of violence and undermined endogenous sources of moderation based on cultural, institutional, and political conditions. State repression to implement a counter-terrorism strategy has radicalized the group, created incentives to find international sympathizers, and contributes to fragmentation that impedes political solutions. A comparison with rebellions in the oil producing Niger Delta helps identify some barriers to and opportunities for conflict resolution.
Probing the neutral fraction of the IGM with GRBs during the epoch of reionization

We show that near-infrared observations of the red side of the Lya line from a single gamma-ray burst (GRB) afterglow cannot be used to constrain the global neutral fraction of the intergalactic medium (IGM), X H , at the GRB's redshift to better than δx H ∼0.3. Some GRB sightlines will encounter more neutral hydrogen than others at fixed x H owing to the patchiness of reionization. GRBs during the epoch of reionization will often bear no discernible signature of a neutral IGM in their afterglow spectra. We discuss the constraints on X H from the z = 6.3 burst, GRB050904, and quantify the probability of detecting a neutral IGM using future spectroscopic observations of high-redshift, near-infrared GRB afterglows. Assuming an observation with signal-to-noise ratio similar to the Subaru FOCAS spectrum of GRB050904 and that the column density distribution of damped Lya absorbers is the same as measured at lower redshifts, a GRB from an epoch when x H =0.5 can be used to detect a partly neutral IGM at 97 per cent confidence level ≈10 per cent of the time (and, for an observation with three times the sensitivity, ≈30 per cent of the time).
Implications of the unusual structure in the pp correlation from Pb+Pb collisions at 158 AGeV

The recent NA49 measurement of two-proton correlation function shows an interesting and unexpected structure at large relative momentum. Applying source imaging techniques to the measurement, we find an unusually steep drop-off in the two-proton source function. We show that the steep drop-off is due to the structure in the correlation and the drop-off cannot be explained using conventional correlation analysis. We suggest possible physics reasons for the unusual source function.
Sleep in Midlife Women

Correspondence Kathryn A. Lee, RN, PhD, CBSM, FAAN, Department of Family Health Care Nursing, School of Nursing, University of California-San Francisco, San Francisco, CA 94143-0606. kathryn.lee@nursing.ucsf. edu Midlife is de¢ned as the time between menopause and old age, the ¢fth and sixth decades of life, when women are still relatively healthy and physically active. These two decades should be a time of stability and a time for enjoying relationships with family and friends, but in today’s society this may also be a time when midlife women are still raising their own young children or raising their grandchildren. They may also be caring for elderly family members or be widowed, poor, or living with chronic illness.
Spatial prediction and ordinary kriging

Suppose data {Z(s i ):i=1, ..., n} are observed at spatial locations {s i :i=1, ..., n}. From these data, an unknownZ(s 0) is to be predicted at a known locations 0c, or, ifZ(s0) has a component of measurement error, then a smooth versionS(s 0) should be predicted. This article considers the assumptions needed to carry out the spatial prediction using ordinary kriging, and looks at how nugget effect, range, and sill of the variogram affect the predictor. It is concluded that certain commonly held interpretations of these variogram parameters should be modified.
Stereoselective electrochemical and chemical reductive silylation of bicyclic geminal dihalocyclopropanes. Effects of ultrasound

Abstract Electrochemical reduction of bicyclic 1,1-dibromocyclopropanes in DMF or THF at a sacrificial magnesium anode in the presence of chlorotrimethylsilane proceeds with replacement of one or both bromine atoms by the trimethylsilyl group, depending on the amount of current passed. A novel ultrasonically induced “anodic reduction” process is described: sonication during electrolysis results in an apparent increase in current efficiency. This has been shown to involve sonochemical formation of the same products at the anode which are produced electrochemically at the cathode.
Two-hop interference channels: Impact of linear time-varying schemes

We consider the two-hop interference channel (IC) with constant real channel coefficients, which consists of two source-destination pairs, separated by two relays. We analyze the achievable degrees of freedom (DoF) of such network when relays are restricted to perform scalar amplify-forward (AF) operations, with possibly time-varying coefficients. We show that, somewhat surprisingly, by providing the flexibility of choosing time-varying AF coefficients at the relays, it is possible to achieve 4/3 sum-DoF. We also develop a novel outer bound that matches our achievability, hence characterizing the sum-DoF of two-hop interference channels with time-varying AF relaying strategies.
AN X-RAY SIZE-TEMPERATURE RELATION FOR GALAXY CLUSTERS: OBSERVATION AND SIMULATION

We show that galaxy clusters conform to a tight relation between X-ray isophotal size RI and emission-weighted intracluster medium (ICM) temperature TX. The best-fit relation for 41 members of an X-ray flux-limited cluster sample is log RI = (0.93 ± 0.11) log (TX/6 keV) - (0.08 ± 0.01); intrinsic scatter in size about the relation is 15%, and for 30 clusters with TX > 4 keV, the scatter is reduced to 10%. The existence of the size-temperature (ST) relation indicates that the ICM structure is a well-behaved function of TX. We use an ensemble of gasdynamic simulations to demonstrate that a cluster population experiencing present-epoch growth nevertheless conforms to an ST relation with scatter similar to that observed; the simulations also exhibit a tight relation between Mvir and TX, providing the suggestion that a similar relation holds for observed clusters. We use the scatter in RI to estimate limits on the rms variation in ICM mass fraction δfICM at constant TX: δf/fICM ≤ 22% (≤14% for clusters with TX > 4 keV). It appears that a mechanism like feedback from galactic winds, which introduces systematic structural changes in the ICM, is required to reproduce the observed slope of the ST relation.
SPITZER OBSERVATIONS OF L429: A NEAR-COLLAPSE OR COLLAPSING STARLESS CORE

We present Spitzer infrared (IR) observations of the starless core L429. The IR images of this core show an absorption feature, caused by the dense core material, at wavelengths ? 70 ?. The core has a steep density profile, and reaches AV > 35 mag near the center. We show that L429 is either collapsing or in a near-collapse state.
Learning to see the trees before the forest: Reversible deactivation of the superior colliculus during learning of local and global visual features

Previous studies have established that deactivation of the superior colliculus severely retards the normally rapid learning of pattern discriminations in the mature cat. The purpose of this study was to test the hypothesis that the midbrain plays an important role in the learning of simple pattern discriminations and that the contribution of this pathway is to the perception of global, rather than local, features of a figure. To answer this question, pattern discrimination learning was studied in three intact cats and in three experimental cats during bilateral reversible deactivation of the superficial layers of the superior colliculus (SC). The animals concurrently learned to discriminate three pairs of compound visual patterns composed of small (local element) Ts or 7s. Congruent and incongruent stimulus pairs were large (global) Ts vs. 7s comprising the same or different local elements, respectively. The random stimulus pair consisted of randomly scattered local elements (Ts vs. 7s). The animals were trained to respond to the large Ts in the congruent and incongruent pairs and the small Ts in the random pair. In the normal cats, learning of the random pair was much slower than the learning of the congruent and incongruent pairs. This finding demonstrated the theory of global precedence, because the animals learned the global features of the congruent and incongruent pairs much more quickly than the local features of the random pair. In contrast, during bilateral deactivation of the superficial layers of the SC, the learning of the incongruent pair was significantly retarded and took longer to learn than the random pair. Congruent and random pair learning rates were unchanged. The specific deficit in learning the incongruent pair indicates that the learning of global, but not local, elements of the visual pattern is impaired during deactivation of the SC. The unimpaired use of local features permitted the animals to learn the congruent and random pairs at normal rates. Therefore, deactivation of the superficial layers of the SC during pattern discrimination learning reverses the precedence for global visual features that is typical of normal learning.
Antioxidant Vitamin C Prevents Decline in Endothelial Function during Sitting

Background This study was designed to test the hypothesis that antioxidant Vitamin C prevents the impairment of endothelial function during prolonged sitting. Material and methods Eleven men (24.2 ± 4.4 yrs) participated in 2 randomized 3-h sitting trials. In the sitting without vitamin C (SIT) and the sitting with vitamin C (VIT) trial, participants were seated for 3 h without moving their legs. Additionally, in the VIT trial, participants ingested 2 vitamin C tablets (1 g and 500 mg) at 30 min and 1 h 30 min, respectively. Superficial femoral artery (SFA) flow-mediated dilation (FMD) was measured hourly for 3 h. Results By a 1-way ANOVA, there was a significant decline in FMD during 3 h of SIT (p 0.05). Conclusions Three hours of sitting resulted in impaired SFA FMD. Antioxidant Vitamin C prevented the decline in SFA FMD, suggesting that oxidative stress may contribute to the impairment in endothelial function during sitting.
Consequences of fully dressing quark–gluon vertex function with two-point gluon lines

We extend recent studies of the effects of quark–gluon vertex dressing upon the solutions of the Dyson–Schwinger equation for the quark propagator. A momentum delta function is used to represent the dominant infrared strength of the effective gluon propagator so that the resulting integral equations become algebraic. The quark–gluon vertex is constructed from the complete set of diagrams involving only two-point gluon lines. The additional diagrams, including those with crossed gluon lines, are shown to make an important contribution to the DSE solutions for the quark propagator, because of their large color factors and the rapid growth in their number.
Modeling the Dynamical Evolution of the M87 Globular Cluster System

We study the dynamical evolution of the M87 globular cluster system (GCS) with a number of numerical simulations. We explore a range of different initial conditions for the GCS mass function (GCMF), for the GCS spatial distribution, and for the GCS velocity distribution. Our simulations include the effects of two-body relaxation, dynamical friction, and mass loss due to stellar evolution. We first confirm that an initial power-law GCMF such as that observed in young cluster systems can be readily transformed through dynamical processes into a bell-shaped GCMF. However, only models with initial velocity distributions characterized by a strong radial anisotropy increasing with the galactocentric distance are able to reproduce the observed constancy of the GCMF at all radii. We show that such strongly radial orbital distributions are inconsistent with the observed kinematics of the M87 GCS. The evolution of models with a bell-shaped GCMF with a turnover similar to that currently observed in old GCSs is also investigated. We show that models with this initial GCMF can satisfy all the observational constraints currently available on the GCS spatial distribution, the GCS velocity distribution, and on the GCMF properties. In particular, these models successfully reproduce both the lack of a radial gradient of the GCS mean mass recently found in an analysis of Hubble Space Telescope images of M87 at multiple locations and the observed kinematics of the M87 GCS. Our simulations also show that evolutionary processes significantly affect the initial GCS properties by leading to the disruption of many clusters and changing the masses of those that survive. The preferential disruption of inner clusters flattens the initial GCS number density profile, and it can explain the rising specific frequency with radius; we show that the inner flattening observed in the M87 GCS spatial distribution can be the result of the effects of dynamical evolution on an initially steep density profile.
The perception of 3-D shape from shadows cast onto curved surfaces

In a natural environment, cast shadows abound. Objects cast shadows both upon themselves and upon background surfaces. Previous research on the perception of 3-D shape from cast shadows has only examined the informativeness of shadows cast upon flat background surfaces. In outdoor environments, however, background surfaces often possess significant curvature (large rocks, trees, hills, etc.), and this background curvature distorts the shape of cast shadows. The purpose of this study was to determine the extent to which observers can "discount" the distorting effects of curved background surfaces. In our experiments, observers viewed deforming or static shadows of naturally shaped objects, which were cast upon flat and curved background surfaces. The results showed that the discrimination of 3-D object shape from cast shadows was generally invariant over the distortions produced by hemispherical background surfaces. The observers often had difficulty, however, in identifying the shadows cast onto saddle-shaped background surfaces. The variations in curvature which occur in different directions on saddle-shaped background surfaces cause shadow distortions that lead to difficulties in object recognition and discrimination.
An overview of the Texas reconfigurable array computer

This paper presents an overview of TRAC and then discusses the system's suitability for some promising applications: Monte Carlo techniques, numerical solutions to linear systems, and data base applications.
Seniority-based coupled cluster theory

Doubly occupied configuration interaction (DOCI) with optimized orbitals often accurately describes strong correlations while working in a Hilbert space much smaller than that needed for full configuration interaction. However, the scaling of such calculations remains combinatorial with system size. Pair coupled cluster doubles (pCCD) is very successful in reproducing DOCI energetically, but can do so with low polynomial scaling (N(3), disregarding the two-electron integral transformation from atomic to molecular orbitals). We show here several examples illustrating the success of pCCD in reproducing both the DOCI energy and wave function and show how this success frequently comes about. What DOCI and pCCD lack are an effective treatment of dynamic correlations, which we here add by including higher-seniority cluster amplitudes which are excluded from pCCD. This frozen pair coupled cluster approach is comparable in cost to traditional closed-shell coupled cluster methods with results that are competitive for weakly correlated systems and often superior for the description of strongly correlated systems.
Silver-Mediated Synthesis of Indolizines via Oxidative C-H functionalization and 5- endo-dig cyclization

Abstract An efficient strategy for the synthesis of indolizines from readily available starting materials via oxidative C–H functionalization and 5-endo-dig cyclization in one step has been demonstrated. This protocol represents wide substrate scope, high functional group tolerance, and selectivity. The structure of the product was confirmed by X-ray crystallographic studies. Ag2CO3 required of this tandem reaction can be recycled and reused after undergoing oxidative reaction.
Surface sulfur measurements on stratospheric particles

The surface chemistries of three particulate samples collected from the lower stratosphere have been determined using a Scanning Auger Microprobe (SAM). These samples are typical of the most abundant natural and anthropogenic particles observed within the stratosphere in the greater-than-2-micron diameter size fraction. Succsessive sputtering and analysis below the first few adsorbed monolayers of all particles shows the presence of a thin (less than 150A) sulfur layer. These sulfur regions probably formed by surface reaction of sulfur-rich aerosols with each particle within the stratosphere. Settling rate calculations show that a typical sphere (10-micron diameter) may reside within the aerosol layer for 20 days and thus provide a qualitative guide to surface sulfur reaction rates.
The coupled orbital and thermal evolution of Triton

The coupled orbital and thermal evolution of Triton is simulated with a model of the satellite having temperature-dependent k/Q (k is the second degree Love number and Q is the tidal dissipation factor). Large changes in orbital and interior properties occur in a short time span of less than 10 to the 8th years. The peak tidal heating rate exceeds the radioactive heating rate by a factor of at least 1000. The ability of tidal heating to overwhelm solid state convection and cause global melting is unequivocally demonstrated. Triton's initial thermal state and composition are shown to control the length of time that passes between capture from heliocentric orbit and the occurrene of swift and dramatic changes in orbital and internal properties. This time interval could have been several billion years.
Growth estimates for orbits of self-adjoint groups

Let \(G\) denote a closed, connected, self-adjoint, noncompact subgroup of \(GL(n,\mathbb R )\), and let \(d_{R}\) and \(d_{L}\) denote respectively the right and left invariant Riemannian metrics defined by the canonical inner product on \(M(n,\mathbb R ) = T_{I} GL(n,\mathbb R )\). Let \(v\) be a nonzero vector of \(\mathbb R ^{n}\) such that the orbit \(G(v)\) is unbounded in \(\mathbb R ^{n}\). Then the function \(g \rightarrow d_{R}(g, G_{v})\) is unbounded, where \(G_{v} = \{g \in G : g(v) = v \}\), and we obtain algebraically defined upper and lower bounds \(\lambda ^{+}(v)\) and \(\lambda ^{-}(v)\) for the asymptotic behavior of the function \(\frac{log|g(v)|}{d_{R}(g, G_{v})}\) as \(d_{R}(g, G_{v}) \rightarrow \infty \). The upper bound \(\lambda ^{+}(v)\) is at most 1. The orbit \(G(v)\) is closed in \(\mathbb R ^{n} \Leftrightarrow \lambda ^{-}(w)\) is positive for some w \(\in G(v)\). If \(G_{v}\) is compact, then \(g \rightarrow |d_{R}(g,I) - d_{L}(g,I)|\) is uniformly bounded in \(G\), and the exponents \(\lambda ^{+}(v)\) and \(\lambda ^{-}(v)\) are sharp upper and lower asymptotic bounds for the functions \(\frac{log|g(v)|}{d_{R}(g,I)}\) and \(\frac{log|g(v)|}{d_{L}(g,I)}\) as \(d_{R}(g,I) \rightarrow \infty \) or as \(d_{L}(g,I) \rightarrow \infty \). However, we show by example that if \(G_{v}\) is noncompact, then there need not exist asymptotic upper and lower bounds for the function \(\frac{log|g(v)|}{d_{L}(g, G_{v})}\) as \(d_{L}(g, G_{v}) \rightarrow \infty \). The results apply to representations of noncompact semisimple Lie groups \(G\) on finite dimensional real vector spaces. We compute \(\lambda ^{+}\) and \(\lambda ^{-}\) for the irreducible, real representations of \(SL(2,\mathbb R )\), and we show that if the dimension of the \(SL(2,\mathbb R )\)-module \(V\) is odd, then \(\lambda ^{+} = \lambda ^{-}\) on a nonempty open subset of \(V\). We show that the function \(\lambda ^{-}\) is \(K\)-invariant, where \(K = O(n,\mathbb R ) \cap G\). We do not know if \(\lambda ^{-}\) is \(G\)-invariant.
New High-Redshift Radio Galaxies from the MIT-Green Bank Catalog*

We present optical identifications and redshifts for 17 new high-redshift radio sources. Fifteen of these sources are radio galaxies; the remaining two are high-redshift, steep-spectrum, radio-loud quasars. These objects were discovered as part of an ongoing study of compact (θ 0.75,Sν ∝ ν-α) sources from the MIT–Green Bank (MG) radio catalog (S5 GHz 50 mJy). Spectra for the optical counterparts were obtained at the W. M. Keck Telescopes and are among the optically faintest radio galaxies thus far identified. Redshifts range between 0.3 and 3.6, with 13 of the 17 at redshifts greater than 1.5. Combining these new radio galaxies with two published MG radio galaxy spectra, we synthesize a composite MG radio galaxy spectrum and discuss the properties of these galaxies in comparison with other, more powerful, radio galaxies at similar redshifts. We suggest a radio power–ionization state relation.
Developing a Mechanistic Understanding of Molecular Electrocatalysts for CO2 Reduction using Infrared Spectroelectrochemistry

The use of infrared spectroelectrochemistry (IR-SEC) as a characterization method for molecular electrocatalysts allows researchers to identify key intermediates and products during the course of an electrochemical reaction. Since such reactions are driven by the application of potential, properly designed cells allow for the examination of the stepwise formation of active species and their subsequent reactivity with substrate. These results can be compared to and independently verified by the concomitant generation of similar species by chemical means. Recently we have used such an approach to characterize the catalytically relevant species and products for the reduction of CO2 by 2,2′-bipyridyl-based ReI and MnI fac-tricarbonyl electrocatalysts. This tutorial review summarizes the requirements of IR-SEC cells and details some examples of mechanistic questions addressed in our laboratory using these methods. IR-SEC is presented as a general method that could be adapted by other laboratories to answer que...
On optimal single-item auctions

We revisit the problem of designing the profit-maximizing single-item auction, solved by Myerson in his seminal paper for the case in which bidder valuations are independently distributed. We focus on general joint distributions, seeking the optimal deterministic incentive compatible auction. We give a geometric characterization of the optimal auction through a duality theorem, resulting in an efficient algorithm for finding the optimal deterministic auction in the two-bidder case and an inapproximability result for three or more bidders.
On the long-time behavior of ferroelectric systems

Abstract This paper presents a new model for the ferroelectric behavior of materials. The usual Maxwell’s equations are supplemented with a constitutive relation in which the electric displacement equals a constant times the electric field plus an internal polarization variable. The latter evolves according to an internal set of Maxwell equations. This model is suggested by one presented by one of the authors for elastic behavior with phase change. The model admits hysteretic behavior. The asymptotic behavior with respect to time is studied and it is shown that the system tends to a steady state in which the polarization is governed by a nonlinear elliptic equation. It is shown that this equation has multiple solutions which correspond to microstructure.
Numerical methods in multidimensional shocked flows

Numerical methods are described for the calculation of two-dimensional time-dependent in viscid flows that contain shocks. Methods are employed which do not consider the shock as in interior moving boundary. The conservation equations describing such flows are differenced by the Lax-Wendroff method. These procedures allow the computed shock-wave transition to be given over two to three mesh widths while accurately giving the proper jump conditions across the discontinuity. Several additional methods are tested and compared. Numerical results are given for oblique and Mach reflections in air. Comparison with the exact solution for ordinary reflection is good. The Mach reflection calculation agrees with experimental photographic data obtained from wind-tunnel tests.
An asymmetric cladding gain-coupled DFB laser with oxide defined metal surface grating by MOCVD

A single growth step ridge waveguide InGaAs-GaAs distributed-feedback (DFB) laser with first-order silicon dioxide defined titanium surface gratings is described. The Ti grating introduces a periodic variation of the loss in the cavity to promote single-frequency emission. The device operates on a single longitudinal and lateral mode, with a threshold current of 20.5 mA, slope efficiency of 0.1 W/A and a side-mode-suppression ratio (SMSR) of approximately 40 dB. Moreover, a narrow spectral linewidth of about 40 kHz is achieved at an output power of 3 mW.
MULTIPLE CONTROL EFFECTOR RATE LIMITING

The effect of the choice of control allocation scheme upon individual control effector rate demands is examined. Three previously reported and one new variation of control allocation schemes are described and compared. The new allocation scheme exploits the maximum attainable moment rates of a given control effector configuration and is called moment-rate allocation. The bases of comparison are single-axis sinusoidal and triangular sawtooth, and multiaxis helical time-varying moment demands placed upon the allocation schemes. It is shown that 1) the choice of allocation scheme greatly affects the onset of effective rate limiting for a particular time-varying input but not consistently for all inputs; 2) widely varying results are obtained depending on whether the input is singleor multiaxis and on the amplitude and shape of the input; 3) none of the observed behavior (except as regards generalized inverses) was easily predictable for arbitrary time-varying inputs; and 4) from the point of view of moment and moment-rate generating capabilities, moment-rate allocation clearly yielded best results.
Causes of financial distress following leveraged recapitalizations

Abstract We report that 31% of the firms completing leveraged recapitalizations between 1985 and 1988 subsequently encounter financial distress. Following their recaps, the distressed firms exhibit (1) poor operating performance due largely to industry-wide problems, (2) surprisingly low proceeds from asset sales, and (3) negative stock price reactions to economic and regulatory events associated with the demise of the market for highly-leveraged transactions. The incidence of distress is not related to several characteristics that have previously been linked with poorly-structured deals. We thus attribute the high rate of distress primarily to unexpected macroeconomic and regulatory developments.