cssi/SciSciGPT-SciSciNet huggingface dataset:
Measurement of aspheric mirror segments using Fizeau interferometry with CGH correction

Large aspheric primary mirrors are proposed that use hundreds segments that all must be aligned and phased to approximate the desired continuous mirror. We present a method of measuring these concave segments with a Fizeau interferometer where a spherical convex reference surface is held a few millimeters from the aspheric segment. The aspheric shape is accommodated by a small computer generated hologram (CGH). Different segments are measured by replacing the CGH. As a Fizeau test, nearly all of the optical elements and air spaces are common to both the measurement and reference wavefront, so the sensitivities are not tight. Also, since the reference surface of the test plate is common to all tests, this system achieves excellent control for the radius of curvature variation from one part to another. This paper describes the test system design and analysis for such a test, and presents data from a similar 1.4-m test performed at the University of Arizona.
Polynitrocubanes: Advanced High-Density, High-Energy Materials**

More powerful and less shock-sensitive explosives are continually being sought for both military and commercial use. Here the qualities a potential candidate must possess to make a good explosive are detailed, and the synthesis of octanitrocubane—a very promising candidate—is described. The physical properties of the nitrocubanes synthesized are also summarized and a proposal for the future is made.
Effects of intracisternal GABA or glutamic acid upon behavioral activity in the rat

It has been postulated that GABA acts as an inhibitor of command neurons, the activity of which initiates behavior. A prediction of this hypothesis is that elevations in functional GABA levels in the brain will cause decreases in behavioral output. Accordingly, in this study rats were injected intracisternally with either saline or one micromole of GABA or its excitatory precursor, glutamic acid, and behavioral activity in a novel environment was recorded as it habituated over the course of the subsequent 4 hours. The activity of the animals that were injected with GABA was greatly decreased, while the activity of the animals that were injected with glutamic acid was apparently unaffected, as compared to animals given saline. These data provide support for the hypothesis that GABA functions as an inhibitory neurotransmitter for behavior-activating command neurons.
Simultaneous reconstruction of speed-of-sound and optical absorption properties in photoacoustic tomography via a time-domain iterative algorithm

Photoacoustic tomography (PAT) is a hybrid imaging modality that combines the advantages of both optical imaging and ultrasound imaging techniques. Most existing reconstruction algorithms assume the speed-of-sound distribution within the object is homogeneous. In certain practical applications, this assumption may not be valid and will result in conspicuous image artifacts. In this work, we investigate the possibility of simultaneously estimating the speed-of-sound and optical absorption properties from data acquired in a PAT experiment. We propose and numerically implement a time-domain iterative algorithm that can reconstruct both the speed-of-sound and optical absorption distribution, by use of a priori information regarding the geometry of the speed-of-sound map. Computer-simulation results are presented to demonstrate the efficacy of the proposed reconstruction method.
A tough biodegradable elastomer

Biodegradable polymers have significant potential in biotechnology and bioengineering. However, for some applications, they are limited by their inferior mechanical properties and unsatisfactory compatibility with cells and tissues. A strong, biodegradable, and biocompatible elastomer could be useful for fields such as tissue engineering, drug delivery, and in vivo sensing. We designed, synthesized, and characterized a tough biodegradable elastomer from biocompatible monomers. This elastomer forms a covalently crosslinked, three-dimensional network of random coils with hydroxyl groups attached to its backbone. Both crosslinking and the hydrogen-bonding interactions between the hydroxyl groups likely contribute to the unique properties of the elastomer. In vitro and in vivo studies show that the polymer has good biocompatibility. Polymer implants under animal skin are absorbed completely within 60 days with restoration of the implantation sites to their normal architecture.
Backbone stability of quaternized polyaromatics for alkaline membrane fuel cells

Abstract The backbone stability of benzyl-trimethyl ammonium (BTMA) functionalized polyaromatics was investigated in two structurally differing polymer architectures; quaternized poly(arylene ether) (PAE) and poly(phenylene) (PP). FTIR analysis indicated the cleavage of aryl-ether linkages in quaternized PAEs under high pH environments, while no backbone degradation in quaternized PP was observed. The backbone degradation of PAEs not only significantly reduced the mechanical properties of the membranes, but also negatively impacted hydroxide conductivity. Membrane electrode assemblies (MEAs) using both PAE and PP membranes showed good initial alkaline membrane fuel cell performance. However, the PAE MEA displayed larger performance losses and failure after only 55 h, due to a mechanical breach. No catastrophic failure of the PP MEA occurred after 300 h, which further confirmed the stability of the polymer backbone.
Predicting fracture localization in folded strata from mechanical stratigraphy and fold shape: Case study of east Kaibab Monocline, Utah

Abstract Joints within folds are often localized within zones. These joint clusters may influence the flow of fluids in the subsurface but are often undetectable on conventional seismic lines. Joints develop in folded strata in response to fold shape and mechanical stratigraphy. Mechanical stratigraphy describes the distribution of layers (layer thicknesses) and the nature of the layer contacts. Within folded strata, joints may localize at regions of high curvature within the outer arc of the fold or at regions of interlayer slip along fold limbs. This study compares the observed fracture pattern within the Navajo Formation at East Kaibab Monocline, Utah with those predicted by numerical models in order to validate the modeling technique. The Boundary Element Method model simulates folding of the Navajo Formation; fold shape and mechanical stratigraphy are estimated from field observations. The numerical model matches the observed fracture pattern while the details of fracture localization will be controlled by heterogeneous interlayer material. The technique presented in this study may be used to predict the location and extent of subsurface joint clusters if fold shape can be resolved from seismic lines and mechanical stratigraphy (layer thickness and contact friction) determined from borehole data.
EXPANSION OF ALITE PASTE CAUSED BY GYPSUM FORMATION DURING SULFATE ATTACK

This paper introduces a study carried out to investigate sulfate attack caused by gypsum formation. The aim, specifically, was to study whether gypsum formation can be a factor leading to expansion in concrete exposed to solutions containing sulfate ions. It was found from the laboratory study that alite paste specimens (0.48 water-to-alite ratio) expanded and cracked significantly in 5% Na\d2SO\d4 solution after a “dormant” period of about 1 year. X-ray diffraction confirmed that gypsum was the main product—ettringite does not form in the system, because of the lack of aluminate. The detailed study of the mechanism for expansion and cracking is continuing. These findings confirm the long-term understanding that sulfate attack mechanism is a complicated process. A highlight of the study, therefore, reveals that expansion and cracking of portland cement concrete may not be attributed solely to ettringite formation. Gypsum formation may be a cause leading to expansion and subsequent cracking.. More research is needed in this area.
Control of rectification and permeation by residues in two distinct domains in an inward rectifier K+ channel

Abstract Inwardly rectifying K + channels conduct more inward than outward current as a result of voltage-dependent block of the channel pore by intracellular Mg 2+ and polyamines. We investigated the molecular mechanism and structural determinants of inward rectification and ion permeation in a strongly rectifying channel, IRK1. Block by Mg 2+ and polyamines is found not to conform to one-to-one binding, suggesting that a channel pore can accommodate more than one blocking particle. A negatively charged amino acid in the hydrophilic C-terminal domain is found to be critical for both inward rectification and ion permeation. This residue and a negatively charged residue in the putative second transmembrane segment (M2) contribute independently to high affinity binding of Mg 2+ and polyamines. Mutation of this residue also induces Mg 2+ - and polyamine-independent inward rectification and dramatically alters single-channel behavior. We propose that the hydrophilic C-terminal domain comprises part of the channel pore and that involvement of both hydrophilic and hydrophobic domains in pore lining may provide a molecular basis for the multi-ion, long-pore nature of inwardly rectifying K + channels.
Enhanced oxygen yields caused by double turnovers of Photosystem II induced by dichlorobenzoquinone

Abstract The activity of Photosystem II reaction centers increases in the presence of dichlorobenzoquinone (DCBQ) compared to ferricyanide or dimethylbenzoquinone (DMBQ). We demonstrate that enhanced yields from Photosystem II in the presence of DCBQ depend on flash length (temporal distribution). A broad flash with extended decay enhances oxygen yields while a narrow flash without extended decay (300 ns laser flash) does not. The broad flash causes double turnovers of Photosystem II; the narrow flash does not. Double turnovers of Photosystem II oxygen evolution occur in t ⩾ 5 μs specifically in the presence of DCBQ and do not contribute to increased electrochromic absorption change. The maximal enhancement by DCBQ occurs at pH 6.5 and a DCBQ-to-chlorophyll ratio of 1:1. The phase of oscillations in 140 μs delayed fluorescence is advanced by DCBQ as expected of double turnovers in Photosystem II reaction centers. We conclude that DCBQ is not accepting electrons from normally inactive Photosystem II reaction centers but is facilitating double turnovers of normally active reaction centers. If care is taken to avoid double turnovers, the concentration of Photosystem II reactions centers active in oxygen evolution is 1.9 mmol/mol chlorophyll in peas.
Application of the argon laser to dentistry

A review was conducted to determine specific areas of application of the argon laser to dentistry. When appropriate, comparisons between the argon laser and other treatment methods were made. It was concluded that the argon laser has applicability in composite resin placement, in enamel and dentin bonding procedures, in preventive dental therapies, and in endodontic procedures.
Improved subsurface land mine recognition using high-boost fusion between passive Stokes vector imagery

Detection and clearance of subsurface land mines has been one of the challenging humanitarian and military tasks. Passive polarization-based imagery has played important role achieving this task. This paper presents new fusion technique where polarization-based imagery is fused with traditional intensity imagery using high-boost approach. The main idea of the high-boost approach used in this paper is to give the polarization imagery obtained from the Stokes vector imagery more weight in forming the final fused image. It is shown that the proposed technique improves the recognition of surface land mines. This improvement is shown using correlation performance metrics derived from wavelet-filter joint-transform correlation algorithm used for pattern recognition.
Heat shock regulates the respiration of cardiac H9c2 cells through upregulation of nitric oxide synthase.

Mild and nonlethal heat shock (i.e., hyperthermia) is known to protect the myocardium and cardiomyocytes against ischemic injury. In the present study, we have shown that heat shock regulates the r...
In situ nitrided titanium alloys: Microstructural evolution during solidification and wear

Abstract Surface and subsurface structural evolution during sliding wear of two in situ nitrided titanium alloys, β Ti–35Nb–7Zr–5Ta (TNZT) and α/β Ti–6Al–4V (Ti64), was studied by cross-sectional transmission electron microscopy coupled with precession electron diffraction. In situ nitriding during the laser engineered net shaping (LENS™) process resulted in the formation of hard and wear-resistant Ti 2 N + TiN phases and nitrogen-enriched α phase in TNZT and Ti64, respectively. Subsurface structural analyses of the worn nitrided TNZT revealed the tendency of α grains, and to greater extent β grains, to undergo severe plastic deformation, forming a heavily grain-refined nanocrystalline α and β tribolayer. Corresponding precession–orientation imaging phase maps were used to determine the orientation and percentage of α and β-Ti in the worn nitrided TNZT. The maps revealed that the nanocrystalline grains of soft/compliant β are much smaller (10–100 nm) than hard/stiff α grains (>100 nm). Wear reduction is due to the combination of the above phases and the increase in the alignment of {0 0 0 2}-textured coarser α grains along the sliding direction in absence of texture in the highly refined β grains. Conversely, nitrided Ti64 exhibited slightly increasing wear, despite higher hardness, due to the change in sliding-induced deformation mechanism where shear bands formed and networked leading to brittle fracture and third body abrasive wear particle generation.
In Memory of Michael Pressley: A Role Model for 21st-Century Educational Psychologists

This article honors the contributions of Michael Pressley and examines 5 roles that were critical to his work as an educational psychologist: teacher, scholar, critic, builder, and mentor. We draw on Michael's life to illustrate how he carried out each of these roles and propose that educational psychologists in higher education in the new millennium should assume all 5 of these roles throughout the majority of their careers.
Nuclear polarization in muonic He ions

Abstract A simple application of second-order perturbation theory is shown to provide an accurate method to evaluate nuclear polarization effects in light muonic atoms. The technique, in conjunction with oscillator nuclear wave functions, is used to evaluate the effect on the splitting of the 2 P 3 2 -2 S 1 2 states of muonic 3 He and 4 He. Comparisons with recent experimental measurements in 4 He and with other calculations are presented. We find a small discrepancy which could be accounted for by a slightly larger nuclear radius than the presently accepted value.
Significance evaluation of the effects of environmental factors on the lipid accumulation of Chlorella minutissima UTEX 2341 under low-nutrition heterotrophic condition.

Abstract The effects of a variety of environmental factors on lipid accumulation of Chlorella minutissima UTEX 2341 under low-nutrition conditions were investigated. The growth of UTEX 2341 reached the exponential phase on the 1st day in low-nutrition medium. And the highest biomass productivity of 3.07 g L−1 d−1 was achieved on the 2nd day. The optimum pH and temperature for lipid accumulation were 6 and 20 °C respectively. 43.69 g L−1 of NaCl and 0.11 mmol L−1 of Fe(III) resulted in higher lipid content, analyzed by Design-Expert. And then under nitrogen starvation stress, the lipid content reached 22.84%. Meanwhile, the lipid yield was 2.5 g L−1. The yield coefficient against carbon was 0.36 g g−1, which was 4.68 times as much as that in OM medium. With the high proportion of C16 and C18 in the lipids, C. minutissima UTEX 2341 was proved to be a potential option for renewable biodiesel production.
Maprotiline poisoning in a child

A 6-year-old girl presented with tonic-clonic seizures and generalized convulsions lasting several minutes. A serum drug screen revealed maprotiline, and the estimated intake was 12 mg/kg. Despite initial neurologic impairment on discharge, follow-up 6 months later showed normal neurologic function in the patient. This report describes that case and discusses the toxicity associated with maprotiline and its management.
P-197L: Late-News Poster: Demonstration of High Performance TFTs on Silicon-on-Glass (SiOG) Substrate

This report is an introduction to a new silicon-on-glass (SiOG) substrate and device technology. The fabrication and analysis of CMOS devices fabricated using SiOG are presented. The SiOG devices are comparable to those fabricated on SOI wafers with respect to carrier mobility and off-state leakage current. This technology clearly demonstrates the potential for system-on-panel integration.
Most but not all bottom-up interactions between signal properties improve categorization

The massive acoustic redundancy of minimally contrasting speech sounds, coupled with the auditory integration of psychoacoustically similar acoustic properties produces a highly invariant percept, which cannot be improved by top-down feedback from the lexicon. Contextual effects are also bottom-up but not all entirely auditory and may thus differ in whether they affect sensitivity or only response bias.
Post-extubation dysphagia in trauma patients: it's hard to swallow.

Background There is a significant incidence of unrecognized postextubation dysphagia in trauma patients. The purpose of this study was to evaluate the incidence, ascertain the risk factors, and identify patients with postextubation dysphagia who will require clinical swallow evaluation. Methods A prospective observational study was performed on 270 trauma patients. Bedside clinical swallow evaluation was done within 24 hours of extubation. Logistic regression analysis was used to adjust for confounding variables. Results The incidence of oropharyngeal dysphagia (OD) in our study was 42%. Ventilator days was the strongest independent risk factor for OD (3.6 vs 8.0, P Conclusions Trauma patients requiring mechanical ventilation for ≥2 days are at increased risk for dysphagia and should undergo routine swallow evaluations after extubation.
Pulseless electrical activity during electroconvulsive therapy: a case report.

Background: Arrhythmias resulting in cardiac arrest during electroconvulsive therapy have been reported. Most reported cases of cardiac arrest had asystole as the initial rhythm. Pulseless electrical activity as an initial rhythm of cardiac arrest during electroconvulsive therapy has never been reported. Also, thromboembolism after inflation of pneumatic tourniquet during lower limb surgery has been reported but never following tourniquet inflation during an electroconvulsive therapy. Case presentation: We report a case involving an 81- year- old female who presented to us for an electroconvulsive therapy for severe depression and developed pulseless electrical activity immediately after electroconvulsive therapy. She was successfully resuscitated and was later found to have bilateral pulmonary emboli with a complete occlusion of the right lower lobe pulmonary artery. The source of embolus was from her left lower extremity deep venous thrombus, which we believe, got dislodged intraoperatively after inflation of pneumatic tourniquet. Our patient not only survived the massive pulmonary embolus, but also showed significant improvement in her mental status compared to her pre-admission level at the time of discharge to a sub-acute rehabilitation centre. Conclusion: We recommend that patients who are elderly and at high risk of thromboembolism should selectively undergo a preoperative doppler ultrasound for deep venous thrombosis. Also, selective application of tourniquet in the upper limb, to monitor for seizure activity, would reduce the incidence of pulmonary thrombo-embolism as embolic events are significantly less from deep venous thromboses of upper extremities when compared to lower extremities.
DNA display II. Genetic manipulation of combinatorial chemistry libraries for small-molecule evolution.

Biological in vitro selection techniques, such as RNA aptamer methods and mRNA display, have proven to be powerful approaches for engineering molecules with novel functions. These techniques are based on iterative amplification of biopolymer libraries, interposed by selection for a desired functional property. Rare, promising compounds are enriched over multiple generations of a constantly replicating molecular population, and subsequently identified. The restriction of such methods to DNA, RNA, and polypeptides precludes their use for small-molecule discovery. To overcome this limitation, we have directed the synthesis of combinatorial chemistry libraries with DNA “genes,” making possible iterative amplification of a nonbiological molecular species. By differential hybridization during the course of a traditional split-and-pool combinatorial synthesis, the DNA sequence of each gene is read out and translated into a unique small-molecule structure. This “chemical translation” provides practical access to synthetic compound populations 1 million-fold more complex than state-of-the-art combinatorial libraries. We carried out an in vitro selection experiment (iterated chemical translation, selection, and amplification) on a library of 106 nonnatural peptides. The library converged over three generations to a high-affinity protein ligand. The ability to genetically encode diverse classes of synthetic transformations enables the in vitro selection and potential evolution of an essentially limitless collection of compound families, opening new avenues to drug discovery, catalyst design, and the development of a materials science “biology.”
Resistivity of Interstitial Atoms and Vacancies in Copper

The residual resistivity associated with the presence of interstitial atoms or vacancies in copper is studied with particular attention devoted to the scattering of conduction electrons resulting from lattice distortions surrounding the imperfections. For interstitials this scattering is found to be an order of magnitude larger than that from the defect itself. For vacancies it is smaller but still important. Interference between scattering from the defect and the surrounding lattice distortion is computed and found to be very small. The calculated resistivity associated with one atomic percent of interstitial atoms is 10.5 \ensuremath{\mu}ohm cm. The corresponding value for vacancies is 1.5 \ensuremath{\mu}ohm cm. Using nominal values for the energy of formation of these defects, the stored energy to resistivity ratios associated with interstitials, vacancies, and interstitial-vacancy pairs are 1.4, 3.4, and 1.6 cal/g per \ensuremath{\mu}ohm cm, respectively.
Origin of organic matter in the Eagle Ford Formation

The Upper Cretaceous Eagle Ford Formation is an organic-rich mudrock of economic significance for oil and gas exploration. In order to facilitate a better understanding of paleoceanographic conditions during Eagle Ford deposition, this study integrates the isotope chemistry of bulk organic matter with inorganic geochemical data. Measurements of total organic carbon (TOC), total N, ![Formula][1] , ![Formula][2] and inorganic major, and trace elements were taken from 166 Eagle Ford and Pepper Formation outcrop samples from McLennan County, central Texas. These data reveal the chemostratigraphic character and the evolution of Cretaceous seawater chemistry on the Texas shelf and allowed the identification of six distinct chemofacies that are useful for correlation purposes. Based on these data, changing paleoredox conditions were documented ranging from normal marine (oxic) conditions associated with the Pepper Formation, anoxic conditions associated with the Lower Eagle Ford Formation, suboxic conditions associated with most of the upper Eagle Ford, and then a return to normal marine conditions at the top of the Eagle Ford Formation. The high TOC content of the Lower Eagle Ford was most likely caused by high productivity that in turn drove conditions to anoxia. Geochemical data that correlate well with TOC were used to identify intervals of potential organic enrichment. [1]: /embed/mml-math-1.gif [2]: /embed/mml-math-2.gif
Rhenium(V) Oxo Complexes of Novel N2S2 Dithiourea (DTU) Chelate Ligands: Synthesis and Structural Characterization

The compounds RNHC(S)NH(CH2)nNHC(S)NHR were prepared in a search for new, relatively small N2S2 ligands. These dithiourea (DTU) ligands are the first chelates containing two potentially bidentate thiourea moieties. A one-step reaction of 1,3-diaminopropane (1) with aryl or alkyl isothiocyanates or of 1,2-diaminoethane (2) with phenyl isothiocyanate afforded the target ligands in excellent yields (95−98%). The ReVO complexes of RNHC(S)NH(CH2)3NHC(S)NHR ligands were obtained through ligand exchange reactions with Re(V) precursors. The chemistry required neither protection of the sulfur atoms for ligand synthesis nor deprotection prior to metal complexation. The structure of (1-phenyl-3-(3-phenylthioureido)propyl]thioureato)oxorhenium(V) (7a), determined by X-ray diffraction methods, revealed the expected pseudo-square-pyramidal geometry with an N2S2 basal and an apical oxo donor set. Both coordinated N's (Nc) were deprotonated. One uncoordinated N (Nu) was deprotonated, producing a neutral complex containin...
Some Aspects of the Statistical Analysis of “Split Plot” Experiments in Completely Randomized Layouts

Abstract The statistical analysis of completely randomized “split-plot” experiments is discussed from the point of view of the underlying multivariate model. In doing this, first certain well-known aspects of the parametric case are reviewed; however, attention is primarily directed toward the development of appropriate non-parametric procedures. The general structure of “split-plot” experiments involves N randomly chosen subjects to whom treatments have been assigned according to a completely randomized design and from each of whom is obtained an observation vector, the components of which represent the responses of the subject to each one of several conditions. Hence, the data matrix has the appearance of a set of mixed models, each one of which corresponds to a particular treatment. The different conditions correspond to the “split plot” treatments in agricultural experiments while the different treatments correspond to the “whole plot” treatments. Alternatively, such designs may be interpreted simply ...
Mean stress effects on crack propagation rate and crack closure in 7050-T76 aluminum alloy

Abstract High strength aluminum alloys that are cyclically loaded in tension are known to show increased fatigue crack propagation rates when the mean stress is increased. It has been suggested that this increase in growth rate may be due to a lower crack closure stress. A smaller closure stress results in a higher effective fatigue crack propagation stress. Measurements of the closure stress were made using an extensometer placed across the crack in order to study the effects of crack closure on the fatigue crack growth rate. The closure stress was determined from the change in slope of load-displacement curves. The growth rate data at various mean stresses were plotted as a function of effective stress intensity factor. In all tests the cyclic stress amplitude was 80 MPa. For specimens run at mean stress levels of 44 MPa and 70 MPa the crack faces were found to close, but on increasing the mean stress to above 120 MPa no closure was observed. The growth rate data from specimens run at mean stresses from 44 MPa to 120 MPa coincided when plotted vs effective stress intensity factor but that crack growth rates for a mean stress of 226 MPa were higher than those obtained at lower mean stresses. We concluded that effects other than crack closure also influence the crack growth rate. Much greater scatter was found in the fatigue crack growth rates of our thicker specimens (5.6mm thick) than in our thinner specimens (2.5 mm thick). Indirect measurements of the length over which the crack faces were closed showed that the length closed decreased sharply with increasing mean stress. At a mean stress of 44 MPa the length closed at minimum stress was several millimeters, while at 70 MPa it had been reduced to less than 1mm.
Tracing mercury seawater vs. atmospheric inputs in a pristine SE USA salt marsh system: Mercury isotope evidence

Abstract Salt marshes can be a significant source of MeHg in coastal marine organisms, however the sources and cycling of Hg in salt marsh sediments, and in coastal environments in general, remain unclear. We analyzed surface and cored sediments from a salt marsh and adjacent upland sand dune in Cabretta Island, Georgia, USA, for total mercury (Hg T ), Hg isotopes and trace metal concentrations to better constrain the sources of Hg in this coastal environment. Hg T concentrations are lower in the upland sands (1–6 ng/g) than in the marsh sediments (6–16 ng/g). Hg T shows a positive correlation with total organic content (TOC) and increasing proportion of fines in the sediments. Trace metal concentrations also show a positive correlation with Hg T in the marsh sediments regardless of chemical affinity (i.e. chalcophile, siderophile or lithophile). All these data are consistent with surface adsorption (either directly on to sediments or on to organic matter) as a dominant mechanism of Hg and metals accumulation in the marsh sediments. The surface sediments show significant mass independent fractionation (MIF) of odd Hg isotopes: the upland dune sands have zero to slightly negative Δ 199 Hg (− 0.07‰ to − 0.14‰) and the marsh surface sediments have positive Δ 199 Hg (0.48‰ to 0.79‰). As in the surface samples, well-sorted sand layers in the cored sediments have low Hg concentrations and zero to slightly negative Δ 199 Hg, whereas fine particle-rich layers have higher Hg concentrations and positive Δ 199 Hg values. In the absence of any evidence for MIF of Hg isotopes by bacteria mediated methylation–demethylation reactions, the observed Hg isotope differences between marsh and upland sands can be explained by different sources of Hg. We suggest that local atmospheric Hg deposition dominates the Hg budget in the ombrotrophic upland sand, while the positive MIF in the marsh sediments are consistent with Hg dominantly of seawater origin. While in situ processes, like photoreduction and evasion can overprint the Hg depositional isotope signature, their effect on the sediments is currently unconstrained. Nevertheless, our data show that Hg isotopes can delineate different sources of Hg in a pristine coastal environment and at small spatial scales. Thus natural background isotope variability should be assessed as a baseline when Hg isotopes are used as tracers of Hg in anthropogenically-influenced sites.
An improved method for the extraction of corticosterone from cell homogenates and subcellular fractions of the rat adrenal cortex

An improved technique is described for the extraction and analysis of corticosterone (11 beta,21-dihydroxy-4-pregnene-3,20-dione) from homogenates and subcellular fractions of the rat adrenal cortex. Factors influencing complete extraction of corticosterone were the nature of the organic solvent system and the concentration of the tissue being extracted. The continued activity of steroidogenic enzymes during subcellular fractionation was presented by 0.1 mM 1-benzylimidazole. For optimum extraction, homogenates were diluted 1:12 (v/v) in 0.25 M sucrose, containing 0.1 M potassium hydroxide. Dilute homogenate was mixed with absolute ethanol (1:10, v/v) and extracted three times with diethyl ether (1:5, v/v). Following extraction, corticosterone in each sample was isolated by thin-layer chromatography (TLC), quantitated by radioimmunoassay (RIA), and corrected by measuring the recovery of added H3 corticosterone. With these procedures, 90-100% of corticosterone found in extracts of adrenal homogenates was recovered in extracts of subcellular fractions of the homogenates.
Assessing faculty research productivity in graduate public policy programs

This study assesses the faculty research productivity of 23 graduate public policy programs, and is based upon data from the Social Sciences Citations Index. The results clearly show that a handful of policy programs have outstanding research records: UC Berkeley, Princeton, Michigan, Chicago, Duke, Carnegie-Mellon, Rand, Syracuse, and, of course, Harvard. Most of the rest also have quite commendable records by this criterion.
Lobar emphysema, cystic adenomaloid malformation, pulmonary sequestration, and bronchogenic cyst in infancy and childhood: A clinical group

Abstract Sixty-four cases of congenital cystic lesions of the lung fit comfortably into the following four distinct categories: lobar emphysema—16 cases; cystic adenomatoid malformation—19 cases; pulmonary sequestration—15 cases; and bronchogenic cysts—14 cases. In the symptomatic patient, aggressive diagnostic studies are recommended, with excision of the offending lesion. Surgical treatment, if not unduly delayed, is effective and safe (97% survival in this series) although the postoperative complication rate is high.
Comparative Philosophy of Environmental Regulations

This paper investigates the different ways in which Sweden, Japan, and the United States have attempted to resolve problems of environmental damage caused by air pollution from industrial sources. These three countries share common problems resulting from high industrial development and also common technological and scientific resources to overcome those problems; the solutions they have chosen, however, are very different.
Toward perceptual enhancement of multiple intersecting surfaces

The relative values of a single 2D scalar field can be effectively perceived when the field is represented by height and rendered as a surface in three dimensions. When multiple scalar fields are simultaneously rendered on the same domain, control of additional rendering attributes such as color, transparency, texturing, and lighting is needed for effective perception. However, the transition from foreground to background due to surface intersections can confound accurate surface perception, even for techniques that work well for overlapping non-intersecting surfaces. We propose a general method for decomposing and stratifying multiple intersecting surfaces into layered components to permit complete rendering control of each surface component. We explore different rendering schemes based on stratification values and report initial results from experimentation.
A Theoretical Model Successfully Identifies Features of Hepatitis B Virus Capsid Assembly

The capsids of most spherical viruses are icosahedral, an arrangement of multiples of 60 subunits. Though it is a salient point in the life cycle of any virus, the physical chemistry of virus capsid assembly is poorly understood. We have developed general models of capsid assembly that describe the process in terms of a cascade of low order association reactions. The models predict sigmoidal assembly kinetics, where intermediates approach a low steady state concentration for the greater part of the reaction. Features of the overall reaction can be identified on the basis of the concentration dependence of assembly. In simulations, and on the basis of our understanding of the models, we find that nucleus size and the order of subsequent "elongation" reactions are reflected in the concentration dependence of the extent of the reaction and the rate of the fast phase, respectively. The reaction kinetics deduced for our models of virus assembly can be related to the assembly of any "spherical" polymer. Using light scattering and size exclusion chromatography, we observed polymerization of assembly domain dimers of hepatitis B virus (HBV) capsid protein. Empty capsids assemble at a rate that is a function of protein concentration and ionic strength. The kinetics of capsid formation were sigmoidal, where the rate of the fast phase had second-power concentration dependence. The extent of assembly had third-power concentration dependence. Simulations based on the models recapitulated the concentration dependences observed for HBV capsid assembly. These results strongly suggest that in vitro HBV assembly is nucleated by a trimer of dimers and proceeds by the addition of individual dimeric subunits. On the basis of this mechanism, we suggest that HBV capsid assembly could be an important target for antiviral therapeutics.
Sputtering of two alloy systems by polyatomic ions: AgAu and CuZn

Abstract High-purity, polycrystalline targets of Ag, Au, Cu and Zn, and alloys of AgAu and CuZn, were sputtered with monomer and trimer ions of arsenic at an energy of 45 keV per atom. Sputtered material was collected on high-purity aluminum foils during the approach to steady of the implant (low dose) and beyond (high dose). From an analysis of these collectors with Rutherford backscattering spectroscopy (RBS) the sputtering yields and angular distributions of atoms sputtered were measured. Analysis of the optical photon emission from the sputtered neutral atoms allowed a determination of the steady state fluence and surface fractions for some of the targets. The measured sputtering yields of Ag and Au agreed with measurements made by Thompson and Johar, demonstrating non-linear sputtering under polyatomic ion bombardment. Similar measurements were made with the Cu and Zn targets. The collectors exposed to alloy sputtering were studied for evidence of preferential sputtering enhancement above and beyond linear (mass-related) effects, which might be attributed to an onset of thermal processes as the density of a collision cascade is increased. The alloy targets were also analyzed for evidence of surface segregation and changes in bulk composition beneath the implanted layer.
Localization of inhibin alpha-subunit immunoreactivity in the rat adrenal cortex.

Abstract Inhibin, a water soluble, non-steroidal glycoprotein hormone that inhibits follicle-stimulating hormone secretion, is produced by the gonads and several non-gonadal tissues (placenta, pituitary and brain). This study describes the presence of inhibin alpha-chain-immunoreactive cells in the adrenal cortex of intact adult male rats and the effects of hypophysectomy and adrenocorticotropin treatment on the expression of inhibin in that gland. In intact rats, the majority of the immunoreactive cells were found scattered in the zona glomerulosa and reticularis. The zona fasciculata contained only a few cells immunopositive for the inhibin alpha-chain. No immunoreactive cells were found in the medulla. Hypophysectomy resulted in a dramatic reduction in alpha-subunit immunoreactivity with only scattered cells observed in the zona glomerulosa and reticularis (0 to 2 cells/section). No immunoreactive cells were found in the zona fasciculata or the medulla. Following supraphysiologic adrenocorticotropin administration to hypophysectomized animals, the number of inhibin alpha-chain-immunoreactive cells significantly increased in each zone of the adrenal cortex. The most prominent changes were seen in the zona reticularis. Interestingly, in the adrenocorticotropin-treated animals scattered immunopositive cells were also present in the medulla. Our results suggest that inhibin-related peptide(s) exist within the adrenal gland and that the expression of these peptides is regulated by adrenocorticotropin. Inhibin-related peptide(s) may, therefore, play a paracrine and/or endocrine role in the adrenal function.
Mathematics Instruction for Secondary Students with Learning Disabilities

Secondary students with learning disabilities generally make inadequate progress in mathematics. Their achievement is often limited by a variety of factors, including prior low achievement, low expectations for success, and inadequate instruction. This article will discuss techniques that have been demonstrated to be effective with secondary students who have learning disabilities in mathematics.
Rapid antidepressant response to alprazolam in depressed patients with high catecholamine output and heterologous desensitization of platelet adenylate cyclase

Abstract The present study examined the relationship between 24-hr urinary catecholamine (norepinephrine and epinephrine) output and measures of platelet adenylate cyclase (AC) activity in depressed patients ( n = 17) and control subjects ( n = 10). In both groups, significant inverse correlations were observed when 24-hr urinary catecholamine levels were examined in relation to measures of both receptor-mediated (prostaglandin D 2 and α 2 -adrenergic) and postreceptor-mediated(NaF) platelet AC enzyme activities, suggesting that circulating catecholamines may regulate platelet AC by heterologous (agonist-nonspecific) desensitization of the AC enzyme complex. Depressed patients who had favorable antidepressant responses to alprazolam had significantly higher pretreatment urinary catecholamine output and lower receptor-mediated platelet AC enzyme activities than control subjects, whereas the nonresponders did not. After 8 days of treatment with alprazolam, urinary catecholamine levels declined significantly. In responders, receptor-mediated measures of platelet AC activity increased significantly by day 8 to values comparable to those in control subjects; but similar changes were not observed in nonresponders. Prior to treatment, responders showed a strict linear relationship between receptor-mediated (prostaglandin D 2 ) and postreceptor-mediated (NaF) stimulation of platelet AC activity through the stimulatory guanine nucleotide regulatory protein (Ns), whereas nonresponders did not. This suggests the presence of two distinct coupling
Intercellular adhesion in the cellular slime mold Polysphondylium pallidum inhibited by interaction of asialofetuin or specific univalent antibody with endogenous cell surface lectin

Abstract Previous work has shown that, as amoebae of the cellular slime mold Polysphondylium pallidum become aggregation competent, they accumulate on their cell surface a carbohydrate-binding protein (lectin) named pallidin. These amoebae also possess cell surface receptors, presumed to contain complex oligosaccharides with a high affinity for the endogenous lectin. If lectin-receptor interactions mediate cell-cell contact, then appropriate concentrations of pallidin inhibitors should block cell cohesion. Two potent macromolecular antagonists of the lectin were employed: the desialylated form of the glycoprotein fetuin and the univalent antibody (Fab) prepared against pallidin. We studied the effects of these inhibitors on rotation-mediated aggregation of P. pallidum amoebae under a variety of assay conditions. Amoebae exposed to hypertonic conditions or to antimetabolites (“Permissive conditions”) were selectively blocked from associating by microgram quantities of the lectin inhibitors, whereas cells in isotonic buffer (“nonpermissive condition”) were only slightly affected. A comparison of the morphology of agglutinates formed under the various conditions allows several explanations for the different susceptibilities to inhibition by antipallidin reagents. Although not conclusive, the work supports a model of cell adhesion in this simple eukaryotic system based at least in part on specific interactions between carbohydrate-binding proteins and receptors on adjoining cells.
Sex Trade Behavior Among Heterosexually Active Homeless Men

Sex trade behavior is fairly common among homeless adults and may contribute to higher rates of HIV/AIDS in this population. This study provides a detailed examination of the sex trade-related attitudes and behaviors of homeless men by: (1) determining the prevalence of sex trade-related behaviors, including sex with female sex workers (FSWs); (2) identifying risk factors for having sex with FSWs; and (3) comparing men’s relationships with FSWs and non-FSWs in terms of relationship qualities and HIV-related risk behaviors, such as condom use. Structured interviews were conducted with a probability sample of 305 heterosexually active homeless men recruited from meal lines in Los Angeles. Recent sex with a FSW was reported by 26 % of men, and more likely among those who were older, used crack cocaine, had more sex partners, believed that sometimes men just need to have sex no matter what, and were embedded in networks that were denser and where risky sex was more normative. Compared to non-FSW partners, men with FSW partners felt less emotionally close to them, were more likely to believe the partner had never been tested for HIV, and were more likely to have sex with them under the influence of drugs or alcohol; however, they were not more likely to talk about using condoms or to use condoms with FSWs. Whether the relationship was considered “serious” was a stronger correlate of condom use than whether the partner was a FSW. Implications of these findings for HIV prevention efforts among homeless adults are discussed.
Crystal structure of the receptor-binding domain of human B7-2: Insights into organization and signaling

B7-1 and B7-2 are homologous costimulatory ligands expressed on the surfaces of antigen-presenting cells. Their interactions with CD28/CTLA-4 receptors expressed on T cell surfaces are crucial for the proper regulation of T cell activity. B7-1 and B7-2 display distinct roles in immune regulation, although they are usually considered to have redundant functions. Here, we report the crystal structure of the receptor-binding (Ig V-type) domain of human B7-2 at 2.7-A resolution. Structures of unliganded and liganded B7-1 and B7-2 suggest a physical-chemical basis for the observed functional similarities and differences between these two costimulatory ligands. Of particular note, whereas the majority of the residues mediating B7-1 dimerization are hydrophobic, the B7-2 dimer observed in the B7-2/CTLA-4 complex displays a very hydrophilic dimer interface. These differences provide a mechanism for preventing the formation of B7-1/B7-2 heterodimers. The divergence at the putative dimer interface is also consistent with the lower tendency of B7-2 to dimerize, as shown by the monomeric state of unliganded B7-2 both in solution and crystalline form, and may result in detailed differences in signaling mechanisms associated with B7-1 and B7-2.
Electromagnetics - the uncertain health risks

Considering all the evidences to date in the scientific literature, an association between EM fields at the environmental levels and harmful effects to human is inconclusive or uncertain. However, the available evidences are enough to raise concern by certain segments of the public. In order to manage health risk in the face of scientific uncertainty, authorities may be persuaded to consider precautionary approaches while establishing safety standards and protection guidelines for EM fields. The precautionary principle is another management tool that could be adopted to deal with the health risks associated with EM exposure. It is an extremely conservative decision making principle that leads to prudent actions in the face of uncertainty. Where there is reasonable risk to the public, a prudent action to reduce the risk should be carried out. This procedure should hold even when the scientific proof is inconclusive as long, as the balance of quantitative and qualitative risk, benefit and cost of action justifies it.