cssi/SciSciGPT-SciSciNet huggingface dataset:
An egg envelope component induces the acrosome reaction in sturgeon sperm

The acrosome reaction in Acipenser transmontanus sperm can be induced by a 66,000 dalton glycoprotein that is present in Layer 3 (L3) of the egg envelope and in egg water only following exposure of the eggs to fresh water. When egg water is fractionated on Sepharose CL 6B, the 66,000 dalton glycoprotein-containing fractions possess acrosome reaction inducing activity. Egg water may be species-specific in its ability to elicit the acrosome reaction, as demonstrated by the fact that it has no effect on the sperm of Acipenser fulvescens. Egg jelly possesses no acrosome reaction, inducing activity. The major carbohydrate-containing component of the egg envelope is L3, a layer that contains galactose residues. L3 possesses a 70,000 dalton glycoprotein prior to freshwater exposure and lacks the 66,000 dalton component. If isolated from polyacrylamide gels, the 70,000 dalton glycoprotein elicits acrosome reactions in what appears to be a species specific manner. After freshwater exposure, L3 contains both the 70,000 dalton glycoprotein and the 66,000 dalton glycoprotein that is also present in egg water. The appearance of the 66,000 dalton inducer can be blocked by the incubation of eggs in fresh water containing inhibitors of trypsin activity. Thus, the soluble inducer in egg water may be proteolytically derived from a higher molecular weight complex in the egg envelope.
Effects of hypervelocity impact on honeycomb structures.

Hypervelocity impact effect on structural honeycomb spacecraft wall configurations, stressing design and wall thickness parameters
Perioperative outcome in adults undergoing elective deep hypothermic circulatory arrest with retrograde cerebral perfusion in proximal aortic arch repair: evaluation of protocol-based care.

Objective: The purpose of this study was to describe perioperative outcome in adults undergoing elective proximal aortic arch repair with protocol-based deep hypothermic circulatory arrest (DHCA) with retrograde cerebral perfusion (RCP). Design: Retrospective and observational. Setting: Cardiothoracic operating rooms and intensive care unit. Participants: Seventy-nine consecutive adults undergoing elective proximal aortic arch repair with DHCA (1999-2001). Interventions: None. Main Results: Average age of the patients was 64.9 years. Mean circulatory arrest time was 30.4 ± 8.5 minutes. Perioperative mortality was 7.6%. Perioperative stroke incidence was 3.8%. Tracheal extubation was successful in 87.3% of patients within 24 hours of operation. Of the cohort, 80.8% were discharged from the intensive care unit within 72 hours of surgery. Median length of hospital stay was 7.4 days. Repeat mediastinal exploration because of bleeding occurred in 3.8% of patients. Although perioperative renal dysfunction (defined as >1.5-fold increase in plasma creatinine concentration) developed in 24.0% of patients, only 3.8% required dialysis. Conclusions: The above parameters establish a baseline incidence for major perioperative complications in adults undergoing elective DHCA with RCP for elective proximal aortic arch repair. In approaching the open aortic arch for short periods of circulatory arrest, deep hypothermia with adjunctive RCP is safe and effective.
Free‐radical copolymerization of α‐olefins with ethylene

Ethylene was polymerized at 15,000–25,000 psi at 130–220°C. with free-radical initiators in the presence of 0–10% of C14-labeled propylene, butene-1, and octene-1. Polymer composition was determined by scintillation counting. Molecular weight measurements and polymer unsaturation as detected by infrared analysis gave independent estimates of chain transfer. It was concluded that the major reaction of all α-olefins is copolymerization: chain transfer is a minor reaction. For all α-olefins, r1 (where ethylene is monomer 1) is 3.2–3.3 uncorrected, or 3.4–3.6 corrected for chain transfer.
Phase-modulated phase-resolved photoacoustic FTIR study of calcified tissues

ABSTRACTPhotoacoustic Fourier transform infrared speciroscopy is employed as a nondestructive method of depthprofiling calcified tissues. The enamel layer is depth profiled using both scan and phase modulation. Phaseresolved - phase modulated spectra provide superior localization and reduced photoacoustic saturation. Phasesynthesized spectra derived from the in-phase and quadrature photothermal signals provide all the essentialfeatures to reconstruct the enamel depth profile.INTRODUCTIONThe integrity of the biomineralization process is reflected in the degree of crystallinity of the mineralcomponent of the calcified tissues. Infrared (IR) spectroscopy has been used to assess the crystallinity of physiological ti'2 However, studies by conventional JR spectroscopy require extensive and destructive sample preparation.3 Photoacoustic (PA) detection is explored as a nondestructive means of depth profilingcalcified tissues. Scan and phase modulated PA depth profiling are compared.EXPERIMENTALPA spectra were collected on a Biorad FTS-60A FT-IR using a MTEC 200 PA cell. Depth profiling wascarried out by recording scans at mirror speeds varying from 0.0032 to 0.64 cm/sec. Phase modulated depthprofiles were performed at 400, 200, 100 and 50 Hz modulation frequency using a phase modulationamplitude of two He-Ne laser fringes. Simultaneous in-phase and quadrature detection was achieved with amodel 099-1446 phase demodulator (Biorad). Phase angle was incremented by 18° to obtain a phase resolveddepth profile which was compared to the phase synthesized profiles.RESULTS AND DISCUSSIONFigure 1 presents the rapid scan PA-FT-IR spectrum of the enamel layer of an intact human tooth. The region
What do X-ray crystallographic and electron microscopic structural studies of the RecA protein tell us about recombination?

The Escherichia coli RecA protein has been the most intensively studied enzyme of homologous recombination. Eukaryotic homologs of RecA are now being found, suggesting that the mechanisms and structures of RecA-mediated recombination may be universal in biology. Most of our knowledge of the structure of the RecA-DNA filament has come from low-resolution electron microscopic studies, but a recent crystallographic study has generated an atomic model for the protein. The interpretation of this model is complicated by the fact that the crystal appears to contain the inactive conformation.
Numerical study of vortex reconnection.

With a Biot-Savart model of vortex filaments to provide initial conditions, a finite difference scheme for the incompressible Navier-Stokes equation is used in the region of closest approach of two vortex rings. In the Navier-Stokes solution, we see that the low pressure which develops between the interacting vorticity regions causes the distortion of the initially circular vortex cross section and forces the rearrangement of vorticity on a convective time scale which is much faster than that estimated from viscous transport.
Three-Dimensional Simulation of Cross-Flow Microfilter Fouling in Tortuous Pore Profiles With Semisynthetic Metalworking Fluids

Fluid flow and fouling mechanisms are examined with a three-dimensional simulation of the tortuous, verisimilar geometry of an α-alumina microfilter. Reconstruction of the three-dimensional geometry was accomplished from two-dimensional cross-sectional cuts, obtained from a focused ion beam. A wall collision model and a particle trapping model are developed for the investigation of fouling mechanisms. The reconstructed geometry and the two models were used in computational fluid dynamics to simulate metalworking colloidal particles travelling through and trapping in the tortuous pore paths of a microfilter. Results reveal sharp flux decline initiating from partial pore blocking and subdued flux decline finalizing in cake layer development with steady-state flow. This flow behavior is in agreement with experimental data from earlier studies. The inclusion of the wall collision model and particle trapping model enabled the revelation of cake layer development as a fouling mechanism.Copyright © 2010 by ASME
Mathematics for the future: developing a Head Start curriculum to support mathematics learning

Abstract While mathematics instruction for very young children needs to be age-appropriate in format and content, it also needs to prepare children conceptually for the kinds of mathematics learning that will be expected of them in future years. This perspective, informed by the work of Russian psychologists and educators on a measurement-based approach to early mathematics instruction [e.g., V.V. Davydov, Children’s Capacity for Learning Mathematics, National Council of Teachers of Mathematics, Reston, VA, pp. 109–205], was the basis for an experimental mathematics curriculum which focused on the concept of unit as it applies to enumeration, measurement, and the identification of relations among geometric shapes. The curriculum particularly emphasized two ideas about units that derive from a measurement perspective: first, that the numerical result we obtain from counting or other measurement operations will depend on our choice of a unit; and second, that units of one kind can be combined to form higher-order units or taken apart to form lower-order ones. The curriculum included a weekly project activity conducted by the Head Start teachers, suggestions for supplementary activities, and a weekly home activity for a parent or other family member to carry out with the child. It was implemented with children in three Head Start centers ( N =46; age range 2 years, 9 months–4 years, 7 months at the beginning of the program). To evaluate the curriculum, two assessment instruments (the mathematics subscale of the DSC and a supplementary instrument constructed especially for this study) were administered, at the beginning and again at the end of the school year, to these children and to two comparison groups. One comparison group ( N =48; age range 2 years, 6 months–4 years, 7 months) received a literacy intervention rather than a mathematics one; the other ( N =29; age range 2 years, 8 months–4 years, 7 months) did not receive any experimental intervention. Results showed significant, albeit modest, positive effects of the intervention. The importance of reexamining current beliefs about what is possible—and desirable—within a preschool mathematics curriculum is emphasized.
Estimation and Inference for Logistic Regression with Covariate Misclassification and Measurement Error in Main Study/Validation Study Designs

Abstract In epidemiological studies, continuous covariates often are measured with error and categorical covariates often are misclassified. Using the logistic regression model to represent the relationship between the binary outcome and the perfectly measured and classified covariates, the model for the observed main study data is derived. This derivation relies on the assumption that the error in the continuous covariates is multivariate normally distributed and uses a chain of logistic regression models to describe the misclassification processes. These model assumptions are empirically verified in the validation study, where the misclassified and mismeasured covariates are validated using perfectly measured and classified data. The full data likelihood, including contributions from both the main study and the validation study, is maximized to obtain the maximum likelihood estimates for the parameters of the underlying logistic regression model and of the measurement error model and reclassification mo...
Restricted capacity and rent dissipation in a regulated open access fishery

A common strategy for limiting the total annual catch in a fishery is to restrict entry and season length. We examine the results of this strategy when entry limitation amounts to a limit on capital, but fishing firms can vary an unrestricted input, and thereby use the restricted input more intensively. Under these regulatory constraints, fishing firms will earn rents that depend on the elasticity of substitution between restricted and unrestricted inputs. Using simulations with data from the Alaskan pollock fishery, rents and season length are shown to depend on fish and variable input prices, sometimes in surprisingly non-monotonic ways.
An amino terminal prosequence is required for efficient synthesis of S. cerevisiae a-factor

Abstract The Saccharomyces cerevisiae a-mating pheromones are 12 amino acid lipopeptides whose secretion is dependent on the ABC transporter, Ste6p. The pheromones are synthesized as 36 and 38 amino acid precursors that terminate in a CaaX box (C is Cys, a is an aliphatic residue, and X is the C-terminal amino acid). Posttranslational processing of the a-factor precursors includes at least 5 events. C-terminal processing of the CaaX box includes farnesylation of Cys, removal of the -aaX residues, and methylation of the cysteine α-carboxyl group. The N-terminal steps involve proteolytic cleavages that remove the prosequences. In this report, we have investigated the role of posttranslational modification in the generation of functional a-factor. Wild type, mutant and chimeric forms of a-factor have been expressed in yeast and assessed for their abilities to serve as sources of functional a-factor. We have found that although modification of the CaaX box is necessary, it is not sufficient to generate bioactive a-factor. The amino terminal prosequences are also required. Deletion of these sequences reduces intracellular levels of a-factor resulting in sterility. Glutathione-S-transferase (GST)-a-factor fusions undergo CaaX box processing and membrane localization, but are not substrates for the N-terminal proteases and fail to interact with Ste6p. These results suggest that the amino terminal precursor sequences play a direct role in the generation of functional a-factor.
Some determinants of aggressive behavior induced by lnorphine withdrawal

Male and female rats of Sprague-Dawley and Long-Evans strains were given daily intraperitoneal iniections of morphine sulfate in increasing dosage over a 15-day period to a terminal dose of 405 mg/kg/day. During withdrawal, fighting behavior occurred equally among older male rats (60 days at start of experiment) of both strains, housed in groups of six, but not at all in younger ones (30 days). A strain difference found earlier in 45-day-old rats was confirmed. Females of either strain or age showed no aggressive behavior during withdrawal. Decreasing available cage space increased the number of aggressive encounters, despite a reduction of group size to four. Saline-injected males of either strain rarely displayed aggression. A circadian rhythmicity of such behavior was not found. There was evidence for a seasonal variation in frequency of morphine-withdrawal-induced aggression, levels being higher in summer than in winter.
An algorithm for automatic skin smoothing in digital portraits

We describe an automatic method for beautifying digital portraits by smoothing the skin of the face. The method builds on existing face detection and face feature alignment technology to automatically segment the face and neck areas to be smoothed. A smoothing filter is then applied to these areas. The resulting portraits are enhanced in a subtle and natural fashion.
200, 020, and 002 X-ray peaks in tempered Fe-18 Ni-C martensites

Separate 200, 020, and 002 X-ray peaks were recorded for 0.0, 0.4, and 0.8 wt pct carbon (18 pct Ni) martensites after tempering between 25 and 500°C. The carbon bearing martensites studied here have been tempered initially enough to eliminate the “high tetragonality” 002 peak usually recorded for as-quenched martensite and the present results apply to tempered martensite only. The peak maximum is taken to determine the lattice parameter and the peak shape is recorded. At all carbon levels and after all tempering treatments, the “crd parameter is larger than or equal to the “a” or “b”. The relative enlargement is very small (0.08 pct) for the lowest carbon level and for any carbon level after severe tempering (500°C for 15 min). For the two higher carbon alloys tempered at temperatures below 400°C (for 15 min) the “c” parameter is significantly larger than the “a” and “b” and for the 0.4 wt pct C alloy the “b” is significantly smaller than the“a” whereas in the 0.8 pct C alloy the “b” is slightly larger than the “a”. Within experimental error the mean volume of the unit cell does not change during the tempering studied here and is nearly unaffected by the initial carbon content. This indicates that little (at most 0.1 wt pct) carbon is dissolved in tempered martensite. In the low carbon alloy the peaks are symmetric and sharpen symmetrically during tempering. In the higher carbon alloys the peaks are nearly symmetric and sharp after severe tempering. After less severe tempering the 002 peak is asymmetrically broadened toward lower9 values (higher lattice parameters) whereas the 200 and 020 peaks are asymmetrically broadened toward higher 0 values corresponding to lower lattice parameters. This collection of results is tentatively interpreted as being due to strains in martensite due to transformation induced substructure and precipitated carbides.
Leading quantum correction to the Newtonian potential

I argue that the leading quantum corrections, in powers of the energy or inverse powers of the distance, may be computed in quantum gravity through knowledge of only the low-energy structure of the theory. As an example, I calculate the leading quantum corrections to the Newtonian gravitational potential.
Urban Contamination of the Chicago/Coastal Lake Michigan Atmosphere by PCBs and PAHs during AEOLOS

Air concentrations of PCBs and PAHs were measured in the urban/industrial complex of Chicago, IL, over southern Lake Michigan, and in a non-urban area as part of the AEOLOS (Atmospheric Exchange Over Lakes and Oceans) Project. Air samples were collected simultaneously in intensive experiments during May and July 1994 and January 1995 in order to determine the influence of contaminated air masses from the Chicago urban/industrial complex on the southern Lake Michigan atmosphere. Gas phase ∑PAH concentrations over the lake ∼10−20 km offshore ranged from 0.8 to 70 ng/m3 while urban air concentrations were 27−430 ng/m3. Photooxidation of gas phase PAHs during the day resulted in daytime over-lake concentrations that were ∼75% less than corresponding nighttime concentrations. Gas phase ∑PCB concentrations ranged from 0.14 to 1.1 ng/m3 over the lake and from 0.27 to 14 ng/m3 in the urban area. ∑PCB concentrations varied seasonally as a result of higher volatilization during the summer. The highest concentration...
OR Practice-A Scenario Approach to Capacity Planning

Production capacity has always been one of the most important strategic variables for the major automobile companies. Decisions by individual companies concerning the overall level of capacity, the type of facility e.g., the level of flexibility, and the location of that capacity e.g., in the United States or abroad are discussed in great detail in the popular business press. In this paper, we describe a model developed for General Motors to aid in making decisions about capacity for four of their auto lines. The model incorporates elements of scenario planning, integer programming, and risk analysis. All the input and output is done using Lotus 1-2-3. Although the presentation is motivated by the particular application in the auto industry, the model represents a general purpose approach that is applicable to a wide variety of decisions under risk. An example in this paper uses actual data, appropriately transformed to ensure confidentiality.
Signal-to-noise improvements in three-dimensional NMR microscopy using limited-angle excitation

The 3D FT variant of spin-echo imaging has previously been successfully used to yield images at microscopic resolution. In obtaining such high resolution, optimization of signal to noise for a given acquisition time is crucial. Using a limited-angle (<60) slice-selective pulse one can improve the effective signal to noise or reduce the experimental time. The spin echo is generated through gradient refocusing. A phantom with T1 of 800 and 1200 ms was used to simulate white and gray matter. Signal intensity was modeled by the expression M=M0sinθ[1−exp(−TRT1)]1−exp(−TRT1)cosθ For TR < 200 ms, limited-angle excitation can yield improvements in signal to noise by greater than a factor of two. These results were experimentally verified on a 1.5 T prototype system (General Electric, Milwaukee, Wis.) configured with gradient and rf coils designed for NMR microscopy. In those cases where signal-to-noise concerns do not require signal averaging beyond that which is inherent in the 3D FT technique, the limited-angle approach can reduce the acquisition time by as much as a factor of four. These results were verified in small animal studies of the brain of a 200 g rat.
Psychophysiological assessment of statements about pain.

A psychophysiological procedure was developed to study the interaction of physiological activity and verbal statements in pain patients. This procedure compared skin potential and heart rate changes occurring during designated baseline, anticipation, reception, processing, and responding stages of a question-answer sequence, in 7 chronic pain patients and 7 non-patient controls. Pain, emotional, and neutral type questions were randomly presented. It was found that the processing of pain questions produced significantly larger physiological changes in pain patients than in the non-pain controls. Such differential psychophysiological responsivity may serve as a basis for the early recognition of chronic pain syndrome and the detection of malingering.
Effect of adenine nucleotides on reactions involving triphosphopyridine nucleotide.

Oxidized TPN, and P-ADPR have been found to be competitive inhibitors of the TPNH-cytochrome c reductase of horse liver. 2′ AMP also competitively inhibits, at somewhat higher concentrations. DPN, ADPR, desamino TPN, 3′ AMP, 5′ AMP, 2′ IMP, and 3′ IMP produce very slight or no inhibition. Glucose-6-phosphate dehydrogenase (Zwischenferment) is inhibited by a concentration of 3·10−3M 2′ AMP, whereas little inhibition results with either 3′ or 5′ AMP. It has been found that DPN when present at high concentrations will react with the yeast phosphogluconic acid dehydrogenase system. Cysteine has been found to activate this enzyme particularly when DPN is used as coenzyme. 2′ AMP inhibits the reduction of both DPN and TPN; the inhibition is much greater when DPN is the electron acceptor. 2′ AMP competitively inhibits the TPN isocitric dehydrogenase from pig heart. 3′ AMP also inhibits but to a lesser degree. The cyclic 2′–3′ AMP, 5′ AMP, and 2′ IMP do not inhibit. 2′ AMP has been found to inhibit the TPN specific isocitrate dehydrogenases from pig heart and brewers yeast, but is without effect on the activity of the DPN specific isocitric dehydrogenases from these sources. Magnesium ions cause a considerable decrease in the inhibition produced by 2′ AMP on the TPN isocitrate system. A similar effect of Mg as well as Mn is observed with the “malic enzyme” from pigeon liver. Both 2′ and 3′ AMP inhibits OAA decarboxylation in pigeon liver; this inhibition requires the addition of metal. TPN stimulation of OAA decarboxylation has been confirmed. TPN reverses the inhibition produced by 3′ AMP, but is less effective against 2′ AMP. None of the adenylic acid isomers at a concentration of 0.01 M influence the yeast alcohol dehydrogenase reaction. 2′ AMP also does not inhibit the oxidation of TPNH by lactic dehydrogenase. The only TPN specific enzyme effect which has been found not to be inhibited by 2′ AMP is the glutathione reductase from peas. The results are discussed with respect to the significance of the monoester phosphate group of TPN in the reactions of this coenzyme.
OF CALCULATIONS PAST AND PRESENT: THE ARCHIMEDEAN ALGORITHM

was a forerunner of a certain type of algorithms used on today's computers. Stimulated by an article of G. M. Phillips [49], which recently appeared in this monthly, we trace the evolution of Archimedes' method, from its geometrical beginning as a means to approximate 7T to its modem version as an analytical technique for evaluating inverse circular and inverse hyperbolic functions. We show that works of Descartes and Gregory provided crucial stepping stones for the transition from geometry to analysis. The resulting analytical procedure, which was formalized in the nineteenth century by Pfaff and Borchardt, is itself in a class of algorithms dependent on arithmetic and geometric means and on invariant transformations of elliptic integrals. This class of algorithms, investigated in 1971 by B. C. Carlson [8], includes Gauss' well-known method for calculating complete elliptic integrals. From the modem standpoint, as shown by (1 1.1) and (11.4) in the sequel, the Archimedean algorithm can be viewed as a consequence of the duplication theorem applied on a degenerate elliptic integral. In the course of our description of the evolution of Archimedes' method, we establish various historical connections among old and new algorithms. The rich diversity of these connections provides much interesting material for the classroom. For pedagogic reasons, we outline key geometrical arguments in order to display the passage from geometry to analysis, and in the last section, we give a list of pertinent references and computational exercises suited for the classroom.
Molecular systematics of the western rattlesnake, Crotalus viridis (Viperidae), with comments on the utility of the D-loop in phylogenetic studies of snakes.

Abstract Crotalus viridis, the western rattlesnake, ranges throughout western North America and has been divided into at least eight subspecies. However, the validity of and relationships among these subspecies and the monophyly of C. viridis as a whole are questionable. We used mitochondrial DNA sequence data from the D-loop region and ND2 gene to examine the relationships among 26 populations of C. viridis and to test the monophyly of this species. These data were analyzed separately and combined using maximum-likelihood and maximum-parsimony. The C. viridis group was monophyletic in all combined analyses, consisting of two strongly divergent clades. We recommend that these clades be recognized as two distinct evolutionary species: C. viridis and C. oreganus. Crotalus viridis should be restricted to the subspecies viridis and nuntius and the remaining subspecies be assigned to the species C. oreganus. Our data do not allow strong evaluation of the validity of the subspecies. We found that the ND2 gene had greater sequence divergences among closely related individuals than the D-loop region, but this relationship reversed at higher levels of divergence. This pattern is apparently due to: (1) ND2 third positions evolving faster than the D-loop but becoming saturated at higher levels of divergence, and (2) the D-loop evolving faster than ND2 second (and possibly first) positions. Our results suggest that the ND2 gene is preferable for examining intraspecific relationships and the D-loop may better resolve relationships between species of snakes. The latter result is contrary to the common perception of the phylogenetic utility of the D-loop. Another unusual result is that the 145 bp spacer region, adjacent to the 5′ end of the light strand of the D-loop, provides greater phylogenetic resolution than the 1030 bp D-loop.
Selective contrast in electron microscopy of crystalline cytochrome oxidase

We have used various techniques for preparation of specimens for electron microscopy in order to selectively contrast different regions of vesicle crystals of cytochrome c oxidase dimers. The results are consistent with a dimer composed of two y-shaped monomers [Fuller et al., J. Mol. Biol. 134 (1979) 305] aligned along one pair of arms with the other pair of arms approximately 70 A apart. The four arms of the monomers lie within and perpendicular to the lipid bilayer in which the dimer is embedded, and the arms protrude approximately 25 A from the lipid bilayer on the matrix side of the membrane. The cytoplasmic side domains of the two monomers split away from one another forming a large cleft in the dimer. Monovalent antibodies (Fab fragments) to subunit IV appear to bind to the two monomer arms which are closely apposed across the two-fold axis of the dimer.
Stereochemistry of some reactions between alkyl S-methyl methylphosphonothioates and chiral alkoxides

Abstract With R-(+) ethyl (or methyl) S-methyl methylphosphonothioate and (+)-pinacolyl alkoxide competitive and highly stereoselective displacements of O-alkyl and S-methyl occur, both reactions being with inversion of configuration. With the enantiomeric S-(-) ethyl (and methyl) S-methyl methylphosphonothioates and (+)-pinacolyl alkoxide the reactions, although still competitive, are no longer stereoselective. In contrast similar reactions with the sodium salt of (-)-menthol, (which might be considered to be the mirror image of (+)-pinacolyl alkoxide) occur highly stereoselectively with the S-(-) but not with R-(+) enantiomers. The displacement of O-alkyl from alkyl S-methyl methyl-phosphonothioates by ethoxide, pinacolyl alkoxide and menthyl alkoxide is not observed when methoxide is the nucleophile; in this case only displacement of S-alkyl group occurs.
The neuroplasmic network in Loligo and Hermissenda neurons

Electron microscopy of the giant axon and smaller fibers of the squid Loligo pealei and of the brain system of the nudibranch Hermissenda crassicornis utilizing improved fixation methods and stereoscopic examination of relatively thick sections (0.2–1.0 μ m) has allowed demonstration of a neuroplasmic network in axons and other neural cellular extensions. The network consists primarily of longitudinally oriented neurofilaments and microfilaments, presumably actin, together with microtubules when present, linked together by a system of thin transverse filamentous bridge elements 2–3 nm in diameter, with a tendency toward a periodicity of ∼40 nm along the axonal longitudinal axis. Internal irrigation of the squid giant axon with fixative following cannulation results in dramatically improved fixation with numerous microtubules being found in the axoplasm, particularly in the subaxolemmal cortical region. The transverse bridges often appear to end at or are structurally continuous with membranous elements such as the axolemma, vesicles, endoplasmic reticulum, and mitochondria. It is thought that some or all of the neuroplasmic network components are involved in axonal transport processes.
Symmetrical and unsymmetrical fault currents of a wind power plant

The size of wind power plants (WPPs) keeps getting bigger and bigger. The number of wind plants in the U.S. has increased very rapidly in the past 10 years. It is projected that in the U.S., the total wind power generation will reach 330 GW by 2030. As the importance of WPPs increases, planning engineers must perform impact studies used to evaluate short-circuit current (SCC) contribution of the plant into the transmission network under different fault conditions. This information is needed to size the circuit breakers, to establish the proper system protection, and to choose the transient suppressor in the circuits within the WPP. This task can be challenging to protection engineers due to the topology differences between different types of wind turbine generators (WTGs) and the conventional generating units. This paper investigates the short-circuit behavior of a WPP for different types of wind turbines. Both symmetrical faults and unsymmetrical faults are investigated. Three different software packages are utilized to develop this paper. Time domain simulations and steady-state calculations are used to perform the analysis.
Charge Order and the Origin of Giant Magnetocapacitance in LuFe 2 O 4

The nature of the charge order in the charge frustrated compound ${\mathrm{LuFe}}_{2}{\mathrm{O}}_{4}$ and its effect on magnetocapacitance were examined on the basis of first-principles electronic structure calculations and Monte Carlo simulations of electrostatic energy. Our work shows that two different types of charge order of almost equal stability (i.e., $\sqrt{3}\ifmmode\times\else\texttimes\fi{}\sqrt{3}$ and chain types) occur in the ${\mathrm{Fe}}_{2}{\mathrm{O}}_{4}$ layers of ${\mathrm{LuFe}}_{2}{\mathrm{O}}_{4}$, and that the ground state of ${\mathrm{LuFe}}_{2}{\mathrm{O}}_{4}$ has a ferrielectric arrangement of the ${\mathrm{Fe}}_{2}{\mathrm{O}}_{4}$ layers with $\sqrt{3}\ifmmode\times\else\texttimes\fi{}\sqrt{3}$ charge order. The giant magnetocapacitance effect of ${\mathrm{LuFe}}_{2}{\mathrm{O}}_{4}$ at room temperature is accounted for in terms of charge fluctuations arising from the interconversion between the two types of charge order, that becomes hindered by an applied magnetic field.
A local cellular model for growth on quasicrystals

Abstract The growth of real valued cellular automata using a deterministic algorithm on 2-dimensional quasicrystalline structures is investigated. Quasicrystals are intermediate between the rigid organization of crystals and disorganized random structures. Since the quasicrystalline structures may be highly symmetric or not, we are able to obtain highly organized and relatively random growth patterns. This deterministic growth produces dendrite, sector, stellar, regular polygons, round, and random DLA-like structures.
Dual core processing: MRB1 is an emerging kinetoplast RNA editing complex

Our understanding of kinetoplastid RNA (kRNA) editing has centered on this paradigm: guide RNAs (gRNAs) provide a blueprint for uridine insertion/deletion into mitochondrial mRNAs by the RNA editing core complex (RECC). The characterization of constituent subunits of the mitochondrial RNA-binding complex 1 (MRB1) implies that it too is vital to the editing process. The recently elucidated MRB1 architecture will be instrumental in putting functional data from individual subunits into context. Our model depicts two functions for MRB1: mediating multi-round kRNA editing by coordinating the exchange of multiple gRNAs required by RECC to edit lengthy regions of mRNAs, and then linking kRNA editing with other RNA processing events.
Atomic Fluorescence Spectrometry in the Inductively Coupled Plasma with a Continuous Wave Dye Laser

The radiofrequency (rf) inductively coupled plasma (ICP) has become a widely used tool for multielement atomic emission analysis. Investigation of excitation processes in spectroscopic systems is very important for the full realization of the analytical utility of any new tool. This is particularly true in the case of plasma sources, where the excitation mechanisms have been shown to be different from those in flames. Mermet and Trassy designed a special rf plasma torch atomic absorption measurement, and Wendt and Fassel determined elements which are strong monoxide formers by atomic absorption measurements in an rf plasma. Using electrodeless discharge lamps as the primary excitation source, Montaser and Fassel reported atomic fluorescence in the ICP tail plume (3 to 5 cm above coil). Higher signals for fluorescence than emission were obtained for cadmium, zinc, and mercury, but a special torch configuration was required.
Contemporary practices in school psychology: A national survey of roles and referral problems

Eight hundred school psychologists who were members of the National Association of School Psychologists were mailed a survey designed to assess their roles, types of referrals, consultation practices, and crisis team involvement. Three hundred seventy (49%) completed surveys were analyzed. Assessment was the most common role followed distantly by consultation. Academic problems were the most frequent type of referral with reading being the most common concern. Of the behavioral referrals, externalizing problems were more frequent than internalizing concerns. Behavioral consultation was the most common model used but less than half of respondents follow all of the stages. Only forty percent use an evaluative component in consultation. A majority of the informants had some involvement with their schools' crisis team. Implications of these findings for training, professional development, and future roles are discussed. © 2002 Wiley Periodicals, Inc.
Perceived media bias and third person effect: Comparisons of Americans, Korean Americans, and Koreans in the United States

Abstract The current study examined the third person effect (TPE) in relation to media coverage of the shooting incident at Virginia Polytechnic Institute and State University (i.e., Virginia Tech.) in April of 2007. TPE refers to tendency to perceive that media coverage influences others (i.e., the third persons) to a greater extent than self (i.e., the first person). Three groups (non-Korean Americans, Korean Americans, and Koreans living in the United States) were compared with one another for their perceptions of media coverage. Specifically, this study investigated how much individuals perceived media to influence themselves versus the American public and the Korean American public. Additionally, the current study examined the extent to which individuals’ focus on the shooter and their perceptions of media bias were related to TPE. The results showed support for TPE in terms of media coverage resulting in negative feelings toward Korean Americans and Koreans. As individuals focused more on the shooter and also perceived greater media bias against Korean Americans, they thought that the media coverage of the incident would be more likely to influence the American public to have negative feelings about Koreans and Korean Americans.
Photonic Chip Recirculating Buffer for Optical Packet Switching

The first on-chip optical buffer is demonstrated with up to 64 ns of delay with 98% packet recovery. The recirculating buffer is implemented using a fast, InP-based switch butt-coupled to a low-loss silica waveguide delay.
Allosteric coupling in pyruvate dehydrogenase kinase 2.

Mitochondrial pyruvate dehydrogenase kinase 2 (PDHK2) phosphorylates the pyruvate dehydrogenase multienzyme complex (PDC) and thereby controls the rate of oxidative decarboxylation of pyruvate. The activity of PDHK2 is regulated by a variety of metabolites such as pyruvate, NAD + , NADH, CoA, and acetyl-CoA. The inhibitory effect of pyruvate occurs through the unique binding site, which is specific for pyruvate and its synthetic analogue dichloroacetate (DCA). The effects of NAD + , NADH, CoA, and acetyl-CoA are mediated by the binding site that recognizes the inner lipoyl-bearing domain (L2) of the dihydrolipoyl transacetylase (E2). Both allosteric sites are separated from the active site of PDHK2 by more than 20 A. Here we show that mutations of three amino acid residues located in the vicinity of the active site of PDHK2 (R250, T302, and Y320) make the kinase resistant to the inhibitory effect of DCA, thereby uncoupling the active site from the allosteric site. In addition, we provide evidence that substitutions of R250 and T302 can partially or completely uncouple the L2-binding site. Based on the available structural data, R250, T302, and Y320 stabilize the “open” and “closed” conformations of the built-in lid that controls the access of a nucleotide into the nucleotide-binding cavity. This strongly suggests that the mobility of ATP lid is central to the allosteric regulation of PDHK2 activity serving as a conformational switch required for communication between the active site and allosteric sites in the kinase molecule.
Fibroma in a Nine-banded armadillo (Dasypus novemcingtus)

Abstract An adult male Nine-banded armadillo (Dasypus nonemcinctus) had a large tumour between the first and second phalanges of the right fore-foot. The tumour was of dermal origin, consisted of dense interlacing bundles of collagen, and contained numerous fibroblasts with elongate nuclei and sparse cytoplasm. Mitotic figures were not observed, there was no evidence of lipid accumulation, and there was no metastasis to regional lymph nodes or other tissues. Electron microscopy showed that the major cells of the tumour were fibroblasts. These did not contain nuclear or cytoplasmic inclusions but had dense bodies in the nucleus and there was a conspicuous absence of lysosomes. This lesion was considered to be a benign fibroma of undetermined aetiology.
The phylogeny of Paralabrax (Perciformes: Serranidae) and allied taxa inferred from partial 16S and 12S mitochondrial ribosomal DNA sequences

Partial sequences of 16S and 12S mitochondrial ribosomal DNA were used to examine the phylogenetic relationships of the primarily eastern Pacific genus Paralabrax (Perciformes: Serranidae) and allied taxa. Paralabrax is considered a basal serranine, which is itself considered the basal subfamily in the Serranidae. Multiple serranines reported closely related to Paralabrax from the genera Serranus, Hypoplectrus, Cratinus, and Centropristis were used as outgroups. Species from the remaining two subfamilies, Epinephilinae and Anthiinae, of the Serranidae were also used in the analyses. The tree of the Serranidae was rooted with the families Polyprionidae and Priacanthidae. Paralabrax, the Serranidae, and the Serraninae were monophyletic in this study. Serranus was found to be paraphyletic. Centropristis, formerly considered the sister taxon to Paralabrax, was not closely related in these analyses. Cratinus agassizii, a monotypic genus from the eastern Pacific, was found to be the sister taxon to Paralabrax. There is greater resolution for intergeneric and subfamily relations than interspecific relationships. A single most parsimonious tree for the interspecific relationships of Paralabrax and allied taxa is proposed. This proposed molecular phylogeny is consistent with known biogeographic processes in the eastern Pacific.
Is human immunodeficiency virus infection a risk factor for Strongyloides stercoralis hyperinfection and dissemination

Strongyloides stercoralis was first identified in post-mortem examination of the gastrointestinal tract of five French soldiers from Cochin, China, in 1876. Since then it has been recognized that infection with this organism can persist for decades. This is due to an autoinfective process whereby rhabditiform larvae that are excreted by the adult worm are converted to infectious filariform larvae in the large intestine where they can then reinfect the host. Under normal conditions this conversion in humans is quite limited, with most conversions occurring in the soil. Occasionally large numbers of rhabditiform larvae transform into infective filariform larvae in the human gastrointestinal tract, which results in a more severe form of the autoinfective cycle. This is referred to as hyperinfection syndrome and can result in dissemination of the larvae to other organs in the host with potentially fatal consequences.
Half-of-the-sites binding of reactive intermediates and their analogues to 4-oxalocrotonate tautomerase and induced structural asymmetry of the enzyme.

4-Oxalocrotonate tautomerase (4-OT), a homohexameric enzyme, converts the unconjugated enone, 2-oxo-4-hexenedioate (1), to the conjugated enone, 2-oxo-3-hexenedioate (3), via a dienolic intermediate, 2-hydroxymuconate (2). Pro-1 serves as the general base, and both Arg-11 and Arg-39 function in substrate binding and catalysis in an otherwise hydrophobic active site. Although 4-OT exhibits hyperbolic kinetics and no structural asymmetry either by X-ray or by NMR, inactivation by two affinity labels showed half-site stoichiometry [Stivers, J. T., et al. (1996) Biochemistry 35, 803−813; Johnson, W. H., Jr., et al. (1997) Biochemistry 36, 15724−15732], and titration of the R39Q mutant with cis,cis-muconate showed negative cooperativity [Harris, T. K., et al. (1999) Biochemistry 38, 12343−12357]. To test for anticooperativity during catalysis, 4-OT was titrated with equilibrium mixtures (≥81% product) of the reactive dicarboxylate or monocarboxylate intermediates, 2 or 2-hydroxy-2,4-pentadienoate (4), respecti...
Retinoids: Inducers of Tumor/Growth Suppressors

The process of carcinogenesis involves genomic disasters that result in inactivation or underexpression of tumor/growth suppressor genes and/or overexpression of oncogenes. Decreased levels of tumor suppressors may result from DNA hypermethylation, mutations, translocation, or transcriptional repression. Therefore, logically, one of the most promising chemopreventive and chemotherapeutic targets appears to be the activation of tumor suppressors. The expression of tumor suppressor genes could be activated by reversal of epigenetic gene silencing by using DNA methyltransferase inhibitors and/or histone deacetylase inhibitors (Zelent et al, 2004). Alternatively, the expression of multiple tumor suppressor genes in cancer cells could be induced by ligand-dependent transcription factors, such as nuclear receptors for the active form of vitamin A, all-trans retinoic acid (ATRA) that belong to the superfamily of steroid/thyroid hormone nuclear receptors. Retinoids (ATRA and its synthetic analogs) exert their anti-proliferative and differentiation effects through retinoic acid receptors (RAR) that function as heterodimers with retinoid X receptors (RXR). RXR, a nuclear receptor for 9-cis retinoic acid, is an obligate partner of RAR in mediating retinoid action. Three distinct isotypes of RAR (, and ) and RXR (, and ) are encoded by separate genes. The RXR–RAR heterodimer binds to retinoic acid response elements (RARE) present in the promoter regions of responsive genes. RARE are direct repeat (DR) of 5'-RGKTCA-3' motifs (where R is A or G and K is G or T) separated by either two (DR-2) or five (DR-5) nucleotides (Nagpal and Chandraratna, 1998).
Critical and maximally informative encoding between neural populations in the retina.

Computation in the brain involves multiple types of neurons, yet the organizing principles for how these neurons work together remain unclear. Information theory has offered explanations for how different types of neurons can maximize the transmitted information by encoding different stimulus features. However, recent experiments indicate that separate neuronal types exist that encode the same filtered version of the stimulus, but then the different cell types signal the presence of that stimulus feature with different thresholds. Here we show that the emergence of these neuronal types can be quantitatively described by the theory of transitions between different phases of matter. The two key parameters that control the separation of neurons into subclasses are the mean and standard deviation (SD) of noise affecting neural responses. The average noise across the neural population plays the role of temperature in the classic theory of phase transitions, whereas the SD is equivalent to pressure or magnetic field, in the case of liquid–gas and magnetic transitions, respectively. Our results account for properties of two recently discovered types of salamander Off retinal ganglion cells, as well as the absence of multiple types of On cells. We further show that, across visual stimulus contrasts, retinal circuits continued to operate near the critical point whose quantitative characteristics matched those expected near a liquid–gas critical point and described by the nearest-neighbor Ising model in three dimensions. By operating near a critical point, neural circuits can maximize information transmission in a given environment while retaining the ability to quickly adapt to a new environment.