cssi/SciSciGPT-SciSciNet huggingface dataset:
Infinite-wavelength analysis for two-phase flow: a three-parameter computer-assisted study of global bifurcations

Abstract A computer-assisted analysis of the long-wave solutions of a two-phase flow model in packed beds is presented, based on the numerical study of global bifurcations. A time-dependent, pulsing flow arises spontaneously for relatively high flow rates of gas and liquid through a packed bed. A recently developed nonlinear model for this phenomenon invokes a travelling wave assumption, and associates the observed wavelike pulses with the existence of long-period periodic solutions in the travelling wave frame. In parameter space, such periodic solutions are located in the neighborhood of certain infinite-period (global) bifurcations, such as homoclinic and double heteroclinic loops. In order to completely map out the travelling wave flow behavior for a given set of fluids and packing, it is necessary to perform a three parameter analysis of these global bifurcations. Using techniques for the continuation of homoclinic and heteroclinic connections, we have examined the relation between homoclinic, heteroclinic (both codimension-1) and double heteroclinic (codimension-2) connections in the model. In parameter space, the families of these bifurcations interact and undergo further qualitative changes. These changes include a crossing of homoclinic connection branches, and the birth of a pair of double heteroclinic connections. We discuss briefly how double heteroclinic loops apparently arise from a local codimension-three singularity where a double-zero eigenvalue occurs simultaneously with the vanishing of a higher (second) order term. We also discuss the relation between the nature of the predicted solutions and experimental observations. This computational study of global bifurcations provides a concise description of the operating region in which pulsing flow can be observed in packed beds.
Lift analysis of a variable camber foil using the discrete vortex-blob method

ECENT research activities in the area of active or "smart" material systems have generated significant interest to develop adaptive lifting surfaces for advanced aircraft and submarine structures. By using integrated actuators and sensors, advanced problems are being addressed in aeroelastic tailoring, vibration and attitude control, and high lift devices.1"6 For example, on submarine aftbodies, compliant attitude control appendages that utilize large out-of-plane foil deformation can provide enhanced lift with reduced wake disturbance compared to conventional full-flying and trailing-edge flapped designs.7~9 To quantify the performance improvements of such control surfaces, an analysis technique is required which can model separated flow at high Reynolds numbers and provide pressure distributions for structure and control system design. The purpose of this Note is to present use of a discrete vortex-blob method to compare lift performance between fixed and variable camber NACA 0012 foils at a Reynolds number of 1 x 10 7 for incompressible flow in two dimensions. The vortex method provides a natural and numerically efficient description of eddies and the vorticity they carry. Since a large number of discrete vortex blobs are used to produce a vorticity field in a Lagrangian reference frame, the method becomes grid free and allows modeling of unsteady flows10 even around multielement bodies of arbitrary shape (conformal mappings are not involved) in nonuniform motion or rotation. Formulation of the Discrete Vortex-Blob Method The discrete vortex-blob method, furthered by Spalart and coworkers11'12 at NASA Ames Research Center, and incorporated in the computer code KPD12, is based on a vorticity formulation of the Navier-Stokes equations for incompressible flow in two dimensions:
Trade and factor movements with three factors and two goods

Abstract With three factors and two goods there are two ‘extreme’ and one ‘middle’ factor. Regardless of technical complementaries in the individual production functions, the extreme factors must be enemies and the middle factor the other factor's friend with constant product prices.
A comparison of aerobic and anerobic photolysis of lens protein

The soluble protein fraction from the cortex of calf lens (ca. 2·5 mg/ml in phosphate buffer, pH 7·4) was photolyzed under both aerobic and anerobic environments. The photolyzed protein was kept at ambinet temperatures, and filters were employed to exclude light Upon photolysis, human lens protein from 14- and 72-year-old normal lenses undergo a photodestruction similar to that found in calf lens protein. But old human lens protein does not give a similar increase of non-tryptophan fluorescence, suggesting that a pre-existing modification prevented its formation.
Fine structure of the alary muscles of the American cockroach.

Abstract The alary muscles of the cockroach, Periplaneta americana , are striated with an A-band of 3·0 to 3·5 μm long. Each muscle fibre was 10 to 12 μm in diameter and Z-lines appeared as small discrete units staggered throughout the sarcoplasm. Mitochondria were conspicuously located near the Z-line areas and were absent from the middle portion of the sarcomere. A transverse membrane system was present which formed dyad structures with a relatively sparse sarcoplasmic reticulum. Cockroach alary muscles were innervated by axons containing electron-dense granules of near 100 nm in diameter. These are thought to be typical of ‘neurosecretory’ axons based on their ultrastructural appearance.
Doppler broadening at all temperatures

We discuss the sharp spectral lines emitted by a gas of particles with rest mass m at all temperatures. By treating the problem as fully relativistic we obtain the exact expressions for line shape and total intensity in the two cases where the gas is confined in a box or freely expanding. At all temperatures the Doppler broadening leads to asymmetric shapes with a blue shift of the peak of the line. For relativistic temperatures of the order kT ⋍ mc2 the line shapes and total intensities are completely different and the free case gives rise to a spectacular increase in total intensity proportional to (4kTmc2)2. For temperatures of kT > mc24 the line shape changes dramatically and for still higher temperatures the infinitely sharp line emitted in the rest frame of the particles gives rise to a black body spectrum.
Role for Mammalian Neutral Sphingomyelinase 2 in Confluence-induced Growth Arrest of MCF7 Cells

Recently, we reported that neutral sphingomyelinase 2 (nSMase2) functions as a bona fide neutral sphingomyelinase and that overexpression of nSMase2 in MCF7 breast cancer cells caused a decrease in cell growth (Marchesini, N., Luberto, C., and Hannun, Y. A. (2003) J. Biol. Chem. 278, 13775–13783). In this study, the role of endogenous nSMase2 in regulating growth arrest was investigated. The results show that endogenous nSMase2 mRNA was up-regulated ∼5-fold when MCF7 cells became growth-arrested at confluence, and total neutral SMase activity was increased by 119 ± 41% with respect to control. Cell cycle analysis showed that up-regulation of endogenous nSMase2 correlated with G0/G1 cell cycle arrest and an increase in total ceramide levels (2.4-fold). Analysis of ceramide species showed that confluence caused selective increases in very long chain ceramide C24:1 (370 ± 54%) and C24:0 (266 ± 81%) during arrest. The role of endogenous nSMase2 in growth regulation and ceramide metabolism was investigated using short interfering RNA (siRNA)-mediated loss-of-function analysis. Down-regulation of nSMase2 with specific siRNA increased the cell population of cells in S phase of the cell cycle by 59 ± 14% and selectively reverted the effects of growth arrest on the increase in levels of very long chain ceramides. Mechanistically, confluence arrest also induced hypophosphorylation of the retinoblastoma protein (6-fold) and induction of p21WAF1 (3-fold). Down-regulation of nSMase2 with siRNA largely prevented the dephosphorylation of the retinoblastoma protein and the induction of p21WAF1, providing a link between the action of nSMase2 and key regulators of cell cycle progression. Moreover, studies on nSMase2 localization in MCF7 cells showed that nSMase2 distributed throughout the cells in subconfluent, proliferating cultures. In contrast, nSMase2 became nearly exclusively located at the plasma membrane in confluent, contact-inhibited cells. Hence, we demonstrate for the first time that nSMase2 functions as a growth suppressor in MCF7 cells, linking confluence to the G0/G1 cell cycle check point.
Teaching Students about In-Group Favoritism and the Minimal Groups Paradigm.

Research on minimal groups demonstrates that arbitrarily creating 2 groups leads to the development of in-group favoritism. Experiments using the minimal groups paradigm show students how easily in-group biases can be created simply by categorizing others. This article describes an in-class activity that demonstrates the power of categorization. Students completed a minimal groups experiment either before or after viewing the video A Class Divided. Regardless of when they viewed the video, students rated their arbitrarily assigned in-group more positively and less negatively than their out-group. These findings spurred lively discussion about the possible relation among categorization, discrimination, and prejudice. Students enjoyed the activity and indicated that it was a valuable technique for demonstrating in-group bias.
Some chemical properties of prunus necrotic ringspot and Tulare apple mosaic viruses

Abstract Tulare apple mosaic (TAMV) and prunus necrotic ringspot (NRSV) are labile viruses stabilized by reducing agents and by a chelating agent, respectively. To understand their differential response to stabilizing agents better, we examined some of the chemical properties of the viruses. Amino acid analysis of the virus proteins revealed that TAMV had a higher percentage of nonpolar and dipolar amino acids while NRSV had a higher percentage of charged amino acids. On a mole percent basis, the cysteine content of NRSV was about 3 times that of TAMV. The amount of sulfhydryl groups reacting with 5,5′-dithiobis(2-nitrobenzoic acid) in TAMV was 2.2 times that in NRSV. This difference in the reactivity of the sulfhydryl groups indicates basic differences in the capsid bonding which may be related to virus stabilization. The RNA base composition and average percent RNA of the viruses were also determined.
Molecular correlates of age-specific responses to traumatic brain injury in mice

Aged traumatic brain injury (TBI) patients suffer higher rates of mortality and disability than younger patients. Cognitive problems common to TBI patients are associated with damage to the hippocampus, a central locus of learning and memory. To investigate the molecular mechanisms of age-related vulnerability to brain injury in a mouse model of TBI, we studied the effects of TBI on hippocampal gene expression in young and aged mice. Young and aged male C57Bl/6 mice were subjected to sham injury or TBI and sacrificed 24 h post-injury. We used laser capture microdissection to obtain pure populations of neurons from the CA1, CA3, and dentate gyrus subfields of the hippocampus. We compared injury-induced gene expression in hippocampal neurons of young and aged mice using quantitative ribonuclease protection assay analysis of linearly amplified mRNA from laser captured neurons. Both increased age and TBI were associated with increased expression of neuroprotective (brain-derived neurotrophic factor), pro-inflammatory (interleukin-1beta), and proapoptotic (caspase-3) genes in mouse hippocampal neurons. Our data support previous reports that suggested the CA3 subregion is highly susceptible to fluid percussion TBI and that age-related changes in gene expression are one potential mechanism of increased vulnerability of the aged brain to TBI.
On certain families of rational functions arising in dynamics

In the last decade, it has become apparent that linear systems, depending on parameters, can occur in surprisingly diverse situations, including families of rational solutions to the Korteweg-de Vries equation or to the finite Toda lattice. Now, it turns out that the "inverse scattering" method employed by Moser [12] to obtain canonical coordinates for the finite, homogeneous Toda lattice is precisely the network synthesis question for RC networks, with parameters. The corresponding question has a negative answer in the multivariable RC or for RLC network synthesis, due to global topological obstructions. The multivariable RC setting is ideal for the analysis of the periodic Toda lattice and the topological obstructions are, in fact, generated by tori.
Aryl Phosphate Complexation by Cationic Cyclodextrins. An Enthalpic Advantage for Guanidinium Over Ammonium and Unusual Enthalpy-Entropy Compensation

The enthalpies and entropies for phosphate complexation by ammonium and guanidinium groups have been compared using cationic cyclodextrins. Aryl phosphate binding by guanidinium hosts is associated with more favorable enthalpies and less favorable entropies, consistent with the idea that guanidinium-phosphate interactions are stronger but more directional than ammonium-phosphate interactions. The slope of an enthalpy-entropy plot suggests that complexation occurs with surprisingly small changes in the order of these systems.
Comparative International Water Research

The early decades of the 21st century will witness increased efforts to learn from water experiences and experiments in distant places and times. Water problems in different regions are increasingly linked through processes of globalization that drive the international diffusion of water technologies, policies, and water use patterns, as well as global climate change that has regional manifestations and teleconnections that cascade through regional hydrologic systems. Information technologies and international organizations will also facilitate comparative international water inquiry. But many areas, including wealthy countries such as the U.S., have been slow to draw upon international experience (Wescoat, Theobald, and Headington 2008). The U.S. National Research Council’s (2004) report on Confronting the Nation’s Water Problems: The Role of Research did not document significant federal support of international water research over the past 25 years, although there have been a variety of U.S. Aid for International Development, U.S. Environmental Protection Agency, and U.S. Army Corps of Engineers international research programs. A century earlier, U.S. water scientists traveled around the world searching for ways to address issues such as development of the Central Valley of California (Wescoat 2000). The problem is extensive – there are few comparisons of major flood hazards problems and programs underway on mainland rivers such as the Ganges-Brahmaputra, Indus, Mekong, Huang Ho, and Yangtze, not to mention the unprecedented Bangladesh Flood Action Plan. Yet there is growing evidence of informal, non-governmental, and historical lines of comparative research that offer promising directions (e.g., Duryog Nivaram on hazards, the Centre for Science and Environment on rainwater harvesting; and the International Rivers Network on basin development). Other sections of this journal issue include many examples of international research, so this section focuses on theoretical, methodological, and organizational trends – and vibrant research opportunities – for comparative research. The first section documents the implicit use of comparison in contemporary water research. The second section argues for a shift to explicit comparative research on critical water problems. The third and fourth sections show how longterm historical research and analogical methods contribute to that goal. The final section outlines how future research along these lines can inform water resource management adjustment, planning, and design.
Effectiveness of intramammary antibiotic therapy based on somatic cell count.

Abstract The Virginia Tech dairy herd was used in a 10-mo study to determine the effect of intramammary antibiotic therapy of quarters with elevated SCC on milk production, subsequent DHIA SCC, and infection status. Cows were assigned randomly to experimental or control groups. Animals in both the control and experimental groups with SCC scores greater than or equal to 5 for the first time during that lactation were quarter sampled, milk was cultured to detect presence of mastitis pathogens, and SCC was determined. All experimental cows with quarter SCC greater than or equal to 5 were treated with an intramammary cephapirin product only in those elevated quarters (DHIA SCC ≥5), regardless of clinical symptoms. Control cows received antibiotic therapy when symptoms were clinical, regardless of SCC. Treatment group had no significant effect on milk production, SCC, or infection status of the cow. Treatment of cows in the experimental group cured 70% of infected quarters, whereas only 50% of infections in the control group were eliminated.
Removing effects of temperature changes from piezoelectric impedance-based qualitative health monitoring

A high frequency NDE technique has been under investigation at the Center for Intelligent Material Systems and Structures. Physical changes in the structure cause changes in the mechanical impedance. Due to the electromechanical coupling in piezoelectric materials, this change in structural mechanical impedance cause a change in the electrical impedance of the piezoelectric sensor. Hence, by monitoring the electrical impedance and comparing this to a baseline impedance measurement, we can determine when structural damage has either occurred or is imminent. However, there are still basic research issues that need thorough investigation before full-scale development and commercialization can take place. Included in these is the effect of temperature on this impedance based NDE technique. Since piezoelectric materials exhibit strong temperature dependency and change in temperature results in marked changes in the structural dynamic responses, any variation that is associated with a change in temperature may be confused as damage. In this paper we analyze temperature effects on the electrical impedance of piezoelectric materials and the structures. We have used an empirical approach due to the complexity of the thermo-electrical- mechanical constitutive models for piezoelectric materials. Through the experimental investigations, it was found that a change in temperature modifies both the magnitude and phase of the electrical impedance of the piezoelectric sensors. A computer algorithm was developed which incorporates temperature compensation into our health monitoring applications. This compensation technique minimizes the effect of temperatures on the electrical impedance of piezoelectric sensors bonded on the structure, in the range from 80 to 160 degrees Fahrenheit. In this paper, we show how it is applied successfully to a bolted pipe structure.
Affinity chromatography of avian type C viral reverse transcriptase: Studies with Rous sarcoma virus transformed rat cells

Abstract An affinity chromatographic procedure is described for the purification of avian type C viral reverse transcriptase. Partially purified viral enzyme specifically binds to and can be eluted in active form from Sepharose coupled to an antibody prepared against the Schmidt-Ruppin reverse transcriptase. Crude extracts of non-virus-producing, RSV-transformed rat tumor cells (XC cells), which contain detectable avian viral gs antigens, have no detectable RSV reverse transcriptase. Mixing experiments indicate that the XC cell extracts do not contain soluble inhibitor(s) of the viral enzyme. These findings suggest that the synthesis or formation of active viral polymerase is depressed in these cells.
Effect of omeprazole on gastric first-pass metabolism of ethanol.

Some commonly used H2-receptor antagonists affect gastric first-pass metabolism of ethanol and lead to unexpectedly high blood alcohol concentrations after consumption of alcohol. To investigate whether omeprazole-a substituted benzimidazole recently approved for clinical use-has a similar harmful effect, we administered a moderate dose of ethanol (0.3 g/kg body wt) orally to seven normal volunteers before and after one week of omeprazole administration (20 mg daily). No significant effect of the drug was found on either mean peak blood alcohol concentrations or on areas under the blood alcohol curve; neither did these parameters differ significantly before or after an acute dose of omeprazole (13.2 mg/kg body wt) in rats, whether ethanol (0.25 g/kg body wt) was administered intragastrically or intravenously.In vitro, omeprazole in concentrations likely to occur in the gastric lumen (0.01–1.0 mM), did not affect gastric alcohol dehydrogenase activity of humans or rats. Thus omeprazole does not affect gastric first-pass metabolism of ethanol and can be considered as a safe choice for the treatment of patients who do not refrain from alcohol consumption during therapy.
Identification and functional characterization of a PP1-binding site in BRCA1.

Abstract The phosphorylation state of the tumor suppressor protein BRCA1 is tightly associated with its functions including cell cycle control and DNA repair. Protein kinases involved in the DNA damage checkpoint control, such as ATM, ATR, and hCds1/Chk2, have been shown to phosphorylate and activate BRCA1 upon DNA damage. We reported previously that protein phosphatase 1α (PP1α) interacts with and dephosphorylates hCds1/Chk2-phosphorylated BRCA1. This study demonstrates the identification of a PP1-binding motif 898KVTF901 in BRCA1. Mutation or deletion of critical residues in this PP1-binding motif substantially reduces the interaction between BRCA1 and PP1α. PP1α can also dephosphorylate ATM and ATR phosphorylation sites in BRCA1 and may serve as a general regulator for BRCA1 phosphorylation. Unlike wild-type BRCA1, expression of the PP1 non-binding mutant BRCA1 protein in BRCA1-deficient cells failed to enhance survival after DNA damage. Taken together, these results suggest that interaction with PP1α is important for BRCA1 function.
The Inverse Scattering Series For Tasks Associated With Primaries: Direct Non-linear Inversion of 1D Elastic Media

In this paper, research on direct inversion for two parameter acoustic media (Zhang and Weglein, 2005) is extended to the three parameter elastic case. We present the first set of direct non-linear inversion equations for 1D elastic media (i.e., depth varying P-velocity, shear velocity and density). The terms for moving mislocated reflectors are shown to be separable from amplitude correction terms. Although in principle this direct inversion approach requires all four components of elastic data, synthetic tests indicate that consistent value-added results may be achieved given only D measurements. We can reasonably infer that further value would derive from actually measuring D , D , D and D as the method requires. The method is direct with neither a model matching nor cost function minimization.
Measuring disease activity and severity in clinical trials and the clinic: same or different?

Standardized criteria to classify systemic lupus erythematosus (SLE) disease activity provide a well-defined methodology to accurately assess SLE. These criteria were recently revised to reflect new knowledge of SLE, both clinical and immunologic. Although developed to classify SLE, these criteria can help with the diagnosis in clinical practice. Research has also provided additional evidence of elevated morbidity and mortality associated with high-dose prednisone therapy, defined as greater than 6 mg/day. At these doses, significant increases in organ damage and cardiovascular events occur. Use of NSAIDs is also known to raise cardiovascular risk. Better options include intermittent intramuscular triamcinolone and hydroxychloroquine. The question of how often to monitor patients with stable SLE is confounded by the many variables showing clinical activity and their average frequency of occurrence. Nevertheless, the evidence suggests that 3 months is the ideal time for follow-up testing. Although there is no confirmed technical standard for measuring SLE disease activity, two primary instruments are available in the clinic: the Physicians Global Assessment and the SELENA-SLEDAI instrument. Each has varying degrees of ability to detect changes in disease activity as well as clinical usefulness. In clinical trials, outcomes are measured by the SLE Responder Index, an instrument that defines response based on criteria from SELENA-SLEDAI, Physicians Global Assessment, and British Isles Lupus Assessment Group index. In clinical practice, responses are primarily based on improvements in disease activity, especially reduced flares. Improvements in serology also matter, as patients with high anti-DNA or low complement are twice as likely to flare during the next year. Quality-of-life criteria are important to patients. Overall, the goal is to accurately measure clinical improvement in the patient's SLE disease activity. Additional file 1 contains an edited transcript of the full presentation.
Effectiveness of inactivated influenza vaccine in children less than 5 years of age over multiple influenza seasons: A case–control study

Abstract The effectiveness of influenza vaccine over multiple influenza seasons in children less than 5 years of age has not been well studied. This is especially important to assess because of the recent recommendation for routine influenza vaccination in childhood. We conducted a matched case–control study to assess the vaccine effectiveness of Trivalent Inactivated Influenza Vaccine (TIV) against laboratory-confirmed, medically attended influenza among children 6–59 months of age at the start of each influenza season from 1999–2000 through 2006–2007 in Olmsted County, MN, USA. The children vaccinated against influenza accordingly to the 2007 ACIP guidelines had a lower risk of laboratory-confirmed medically attended influenza illness (Odds Ratio: 0.14, 95% Confidence Interval: 0.03–0.71) than the unvaccinated children. TIV provided strong protection against laboratory-confirmed medically attended influenza in children 6–59 months old in the fully vaccinated group. This trend continued in the partially vaccinated group (Odds Ratio: 0.27, 95% Confidence Interval: 0.07–0.97) but the protection provided maybe suboptimal.
Correlation of the structure of dextrans to their 1H-n.m.r. Spectra

Abstract Dextran fractions from NRRL strains Leuconostoc mesenteroides B-742, B-1299, B-1355, and B-1501, Streptobacterium dextranicum B-1254, Streptococcus sp. B-1526, and also the native dextrans from L. mesenteroides B-1142, B-1191, B-1402, and L. dextranicum B-1420 were examined in aqueous solution at 90° by Fourier-transform, 1H-n.m.r. spectroscopy. Branching of dextrans through the 2,6-, 3,6-, and 4,6-di-O-substituted α- d -glucopyranosyl residues was correlated to changes in spectral patterns. The major, spectral differences for these dextrans were in the anomeric (4-6-p.p.m.) region. In general, the degree of branching of a dextran can be determined by comparing anomeric-peak integrals; however, the integrals of the displaced, nonlinear, anomeric resonances are also dependent on the type of branching residues present in the dextran. Although the 1H-n.m.r. resonances for the anomeric region identify the presence of non-6-mono-O-substituted α- d -glucopyranosyl residues, these additional resonances provide little discrimination between other residue types, the exception being the 2,6-di-O-substituted residue, which has a clearly displaced resonance. Techniques for the suppression of the interfering resonance of deuterium hydroxide are also discussed.
Trends in global wildfire potential in a changing climate

Abstract The trend in global wildfire potential under the climate change due to the greenhouse effect is investigated. Fire potential is measured by the Keetch-Byram Drought Index (KBDI), which is calculated using the observed maximum temperature and precipitation and projected changes at the end of this century (2070–2100) by general circulation models (GCMs) for present and future climate conditions, respectively. It is shown that future wildfire potential increases significantly in the United States, South America, central Asia, southern Europe, southern Africa, and Australia. Fire potential moves up by one level in these regions, from currently low to future moderate potential or from moderate to high potential. Relative changes are the largest and smallest in southern Europe and Australia, respectively. The period with the KBDI greater than 400 (a simple definition for fire season in this study) becomes a few months longer. The increased fire potential is mainly caused by warming in the U.S., South America, and Australia and by the combination of warming and drying in the other regions. Sensitivity analysis shows that future fire potential depends on many factors such as climate model and emission scenario used for climate change projection. The results suggest dramatic increases in wildfire potential that will require increased future resources and management efforts for disaster prevention and recovery.
Irradiation-resistant primed T cell function.

The experiments described in this paper demonstrate that the ability of primed T cells to provide helper function is irradiation resistant in situ and in vitro, but not in vivo following transfer to another animal. Mice primed with antigen and then lethally irradiated developed humoral immune responses when injected with bone marrow cells and erythrocytes as antigens. Since reconstitution of immunocompetence was not dependent on injection of T cells, this would indicate the existence of irradiation-resistant T cell function in primed mice. Further experiments showed that priming to irradiation-resistant T cell function in situ could be accomplished with as few as 102 sheep red blood cells or 104 goat red blood cells injected intravenously. Priming appears to optimal when done 3–10 days before irradiation, and it appears to be ineffective 25 days or more before irradiation. Primed mice developed both direct and indirect plaque-forming cells. These data are compatible with the idea that irradiation interferes with the ability of primed T cells to migrate or home correctly, but not with their ability to provide helper function.
Characterization of the disulfide bonds and the N-glycosylation sites in the glycoprotein from Rathke's gland secretions of Kemp's ridley sea turtle (Lepidochelys kempi).

Abstract The disulfide bonds and N-glycosylation sites in a glycoprotein from the Rathke's gland secretion of the Kemp's ridley turtle ( Lepidochelys kempi ) have been characterized with respect to peptide sequences and glycan structures. The glycoprotein constitutes about 70% of the total protein in the secretion, and based on partial sequence information, it shows more than 20% identity with both the catalytic (esterases) and the noncatalytic (thyroglobulin) members of the esterase/lipase family of proteins. For the determination of the disulfide locations, the glycoprotein was digested with chymotrypsin, and the three HPLC peptide peaks yielding fluorescent products after treatment with tributylphosphine (Bu 3 P) and 4-(aminosulfonyl)-7-fluoro-2,1,3-benzoxadiazole (ABD-F) were collected. The three fractions were treated with the same reagents in separate experiments, the resulting pairs of ABD-Cys-containing peptides were separated by HPLC, and the sequence of each individual peptide was determined. The peptide identity established that three disulfide bonds existed in the glycoprotein: Cys 65-Cys 91, Cys 254-Cys 265, and Cys 130-Cys 404; the first two of these are conserved in all the members of the esterase family. For the study of the glycosylation sites, the glycoprotein was reduced with Bu 3 P and the SH groups covalently blocked with ABD-F, and the resulting product was digested with chymotrypsin. The glycopeptides were isolated by affinity chromatography, separated by reverse-phase HPLC, and subjected to sequence analysis and fast atom bombardment mass spectrometry before and after separation of the glycans and the peptides through the action of glycoamidase. Three separate glycosylation sites were identified, each containing multiple glycans. The sugar analyses of the hydrolysates of the glycoprotein indicated that only GlcNAc and Man were present as building blocks, and the mass spectrometric data showed that Man 3 GlcNAc 2 -, GlcNAc 2–4 Man 3 GlcNAc 2 -, and possibly GlcNAc 2 Man 2 GlcNAc 2 - were the major glycan structures, distributed differently at the three sites. The three glycosylation sites match three of the nine sites glycosylated in human serum choline esterase, and one of them, Asn 106, is also found as one of two glycosylation sites in the homologous segment of thyroglobulin.
Interactions of Escherichia coli SO-187 tRNAIVal with Bacillus stearothermophilus valine-tRNA synthetase studied by13C-NMR

Abstract Uracil isotopically labelled with 13 C at C4 and C5 has been incorporated into nucleic acids of the Escherichia coli uracil auxotroph, SO-187. [4,5- 13 C]uracil-labeled tRNA I Val was isolated and purified. 13 C longitudinal relaxation times measured at 67.8 MHz demonstrated that the C5 dipole caused a 20–50% increase in the C4 relaxation. Interactions of this tRNA with valine-tRNA synthetase (VTS) purified from Bacillus stearothermophilus were established by 13 C-NMR. Specific spectral changes were seen at 4-thiouridine, ribothymidine and pseudouridine of the ‘bend’ in the three-dimensional structure, and particularly at the uridine-5-oxyacetic acid in the wobble position of the anticodon. Thus, the protein seems to be in contact along the entire tRNA molecule, including the anticodon loop.
Use of affinity chromatography for acetylcholine receptor purification.

Abstract An acetylcholine receptor (AChR) affinity resin was prepared by covalently linking [N-(ϵ-aminohexanoyl)-3-aminopropyl]trimethyl ammonium bromide hydrobromide to agarose. A partially purified membrane protein preparation from the electroplax of Narcine was resolved on this resin into a peak of inactive protein and a peak of protein displaying α-bungarotoxin binding activity. Analysis of the purified toxin binding material by SDS polyacrylamide electrophoresis shows a major band of apparent molecular weight 28,000 and two minor bands of approximately 45,000 and 38,000.
Tight-binding total-energy models for silicon and germanium.

By accurately fitting tight-binding parameters to ab initio band structures from 14 different tetrahedral volumes, tight-binding parametric formulas have been developed for silicon and germanium. The distance dependences for these orthogonal, nearest-neighbor parameters range from ${\mathit{r}}^{\mathrm{\ensuremath{-}}2.5}$ to ${\mathit{r}}^{\mathrm{\ensuremath{-}}3.3}$. Repulsive potentials are added in order to reproduce the total energies for a number of bulk structures. It is found that the repulsive potential needed has the simple form of a pairwise interaction multiplied by a structure-dependent constant. Transferability is shown with good bulk and cluster results.
Sperm-associated sialyltransferase activity

FERTILISATION begins with a specific adhesion between sperm and egg and culminates with the fusion of the male and female pronuclei. In mammals, sperm seem to recognise the zona pellucida surrounding the egg1. This adhesive interaction is the first of many that will take place during subsequent embryogenesis. In molecular terms, these later cell–cell interactions are not generally understood, and the mechanism of sperm–egg recognition is unknown. Conceptually, advances in this area have been rare since Lillie presented the fertilisin hypothesis, and even this has been questioned2. There is evidence to support a model for intercellular recognition that utilises the molecular complementarity inherent in cell surface glycosyltransferases and their respective acceptor molecules3,4. The transferases catalyse the addition of sugars, from sugar nucleotides, to the non-reducing termini of saccharide acceptors. The enzymes are highly specific for both the donor sugar nucleotide and the acceptor, usually an oligosaccharide. For example, sialyltransferases are the class of glycosyltransferases that transfer sialic acid (N-acetylneuraminic acid) from cytidine monophosphate-N-acetylneuraminic acid (CMPNAN) to either glycoprotein, glycolipid, or free oligosaccharide acceptors4. Glycosyltransferases have been reported on the external surfaces of many different cell types and, in some cases, enzyme–substrate complexes between the transferases and their acceptors may be instrumental in the cellular recognition that occurs (reviewed in ref. 5). We report here a study of mouse sperm–egg interactions in terms of the transferase–acceptor hypothesis.
Neuroendocrine lesions of the genitourinary tract.

Neuroendocrine differentiation in tumors of the upper and lower urinary tracts, prostate, and testis is rare. The current review surveys the most significant pathologic and clinical features of primary neuroendocrine lesions at these sites, with emphasis on the cell types from which they derive. As
Is land being degraded? A multi-scale investigation of landscape change in southwestern Burkina Faso

This paper presents the results of a multi-scale investigation of the social and biophysical dimensions of land degradation in three villages in southwestern Burkina Faso. In this region, technological change in the form of animal traction and cotton has combined with massive migration to create pressure on natural resources. These pressures have, in turn, increased farmed areas and decreased fallow periods. Whether this has resulted in widespread land degradation, however, depends on the scale of analysis. At the broad scale, aerial photos confirm farmers' perceptions that their land resource is degraded, showing decreases in forested land, increases in area under cultivation, and increases in areas characterized as degraded. At the field scale, an analysis of soil samples collected from these farmers' fields in 1988 and again in 1996 indicates that there has not been a widespread reduction of soil quality. Soils under continuous cultivation revealed few changes, while soils that were fallowed during the eight-year period showed improvement in nutrient status. A study of agricultural practices illustrates how some farmers are responding to the lack of fallow land by intensifying their production system. They nurture trees on agricultural fields, use more inputs and construct anti-erosion barriers on sloped fields to prevent erosion. Changes apparent on one scale are therefore met with responses which are apparent at other scales. The paper illustrates the importance of farmer perceptions, access to resources and local social structures in determining decisions about agricultural practices. These decisions then shape whether land degradation or land improvement characterize the nature of environmental change. Copyright © 1999 John Wiley & Sons, Ltd.
On the complexity of fixed-priority scheduling of periodic, real-time tasks

Abstract We consider the complexity of determining whether a set of periodic, real-time tasks can be scheduled on m ⩾ 1 identical processors with respect to fixed-priority scheduling. It is shown that the problem is NP-hard in all but one special case. The complexity of optimal fixed-priority scheduling algorithm is also discussed.
Unifying the landmark developments in optimal bounding ellipsoid identification

Abstract : A quite general class of Optimal Bounding Ellipsoid (OBE) algorithms including all methods published to date, can be unified into a single framework called the Unified OBE (UOBE) algorithm. UOBE is based on generalized weighted recursive least squares in which very broad classes of 'forgetting factors' and data weights may be employed. Different instances of UOBE are distinguished by their weighting policies and the criteria used to determine their optimal values. A study of existing OBE algorithms, with a particular interest in the tradeoff between algorithm performance interpretability and convergence properties, is presented. Results suggest that an interpretable, converging UOBE algorithm will be found. In this context, a new UOBE technique, the set membership stochastic approximation (SM-SA) algorithm is introduced. SM-SA possesses interpretable optimization measures and known conditions under which its estimator will converge.
Ramified Recurrence and Computational Complexity I: Word Recurrence and Poly-time

We exhibit a notion of recurrence over free algebras ramified into tiers, based on unfolding an implicit circularity of the recurrence schema; recurrence in two tiers was introduced independently in [4, 13, 24].) We show that the functions generated by ramified recurrence over a word algebra \(\mathbb{A}\) are obtained already using only two tiers, and are exactly the functions computable by a register machine over \(\mathbb{A}\) in time polynomial in the length of the input. For the algebra \(\mathbb{W}\) of words over a binary alphabet, these are exactly the poly-time functions in the usual sense, as shown in [4]. When the medium of computation is the algebra ℕ of unary numerals, then the numeric functions generated are exactly the ones computable in linear space, as shown independently in [2, 10, 21].
Local convergence analysis of conjugate gradient methods for solving algebraic Riccati equations

Necessary and sufficient conditions are given for local convergence of the conjugate gradient (CG) method for solving symmetric and nonsymmetric algebraic Riccati equations. For these problems, the Frobenius norm of the residual matrix is minimized via the CG method, and convergence in a neighborhood of the solution is predicated on the positive definiteness of the associated Hessian matrix. For the nonsymmetric case, the Hessian eigenvalues are determined by the squares of the singular values of the closed-loop Sylvester operator. In the symmetric case, the Hessian eigenvalues are closely related to the squares of the closed-loop Lyapunov singular values. In particular, the Hessian is positive definite if and only if the associated operator is nonsingular. The invertibility of these operators can be expressed as a noncancellation condition on the eigenvalues of the closed-loop matrices. >
Changes in the metabolic profiles of R- and S-warfarin and R- and S-phenprocoumon as a probe to categorize the effect of inducing agents on microsomal hydroxylases.

Abstract The biotransformation of R- and S-warfarin was examined using liver microsomes prepared from both noninduced rats and rats pretreated with Arochlor 1254, β-napthoflavone (BNF), pregnenolone-16α-carbonitrile (PCN), phenobarbital (PB), and 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD). For comparison, the metabolism of a closely related coumarin anticoagulant, R- and S-phenprocoumon, was determined using the same microsomal preparations. In noninduced microsomes the overall metabolism of warfarin was about five times that of phenprocoumon, with 7-hydroxywarfarin as the principle metabolite followed by the 6-, 4′- and 8-hydroxy derivatives (benzylic hydroxylation was not examined). For phenprocoumon a different regioselectivity was observed with 4′ hydroxylation being the greatest followed by 6-, and 7 and 8 hydroxylation. In the case of warfarin, hydroxylation with noninduced microsomes was either nonstereoselective (4′ hydroxylation) or selective for the R-enantiomer. The metabolic pattern observed for phenprocoumon showed hydroxylation to be either nonstereoselective (7 and 8 hydroxylation) or, in contrast to warfarin, selective for the S-enantiomer. Induction of cytochrome P-450 by Arochlor, BNF, and TCDD produced a similar metabolic pattern for both substrates in which 6 and 8 hydroxylation were greatly increased over control levels. In keeping with the pattern obtained from noninduced microsomes, a reversed stereoselectivity was again observed after induction with these three agents, i.e. warfarin metabolism was selective for the R-enantiomer and phenprocoumon metabolism was selective for the S-enantiomer. Based on cytochrome P-450 levels PCN decreased the metabolism of both substrates while PB had no effect. However, the induction with PB was readily apparent when calculations were performed on a per mg protein basis.
Treatment of Nevus Spilus with the Q-switched Ruby Laser

Background Q-switched lasers have shown to be effective in the removal of unwanted cutaneous pigmentation. Benign cutaneous pigmented lesions represent a heterogeneous group. Nevus spilus is a relatively uncommon pigmented lesion characterized by dark, hyperpigmented dots scattered over a tan-colored macule. Objective A cohort of patients with nevus spilus was studied to determine the effects of Q-switched ruby and Q-switched Nd:YAG laser treatment on clearance of pigment and to evaluate potential side effects. Methods Six patients with nevus spilus were treated with the Q-switched ruby laser (QSR). In addition, three lesions received a test treatment with the Q-switched Nd:YAG (QSYAG) laser at 532 or 1064 nm. The results of treatment were documented during follow up visits. Results Most lesions showed a near-complete or complete response to laser treatment. In one case partial hyperpigmentation occurred after treatment and in one case no follow-up could be obtained. In the three cases that received both QSR and QSYAG laser treatment, the QSR laser was shown to be the most effective in removing pigment. Conclusion Nevus spilus can be treated effectively with the Q-switched ruby laser.
Adrenal medullary implants in the rat spinal cord reduce nociception in a chronic pain model.

Abstract Previous work in this laboratory has indicated that the transplantation of adrenal medullary tissue into the subarachnoid space of the rat spinal cord can reduce pain sensitivity to acute noxious stimuli, particularly following stimulation by nicotine. This most likely results from the stimulated release of opioid peptides and catecholamines from the transplanted chromaffin cells. However, chronic pain models may more closely resemble human clinical pain, and the arthritic rat model has been used for screening potential therapeutic strategies. The purpose of the present study was to assess the potential for adrenal medullary tissue implanted into the spinal subarachnoid space to alleviate chronic pain. Adrenal medullary tissue was implanted into adjuvant-in-duced arthritic rats, and changes in body weight and vocalization responses were monitored over the 10 week course of the disease. Results indicate that the severe weight reduction normally associated with this inflammatory arthritis was attenuated by adrenal medullary, but not control, implants. In addition, vocalizations were reduced in animals implanted with adrenal medullary, but not control tissue following nicotine stimulation. This reduction was blocked by the opiate antagonist, naloxone, and partially attenuated by the alpha-adrenergic antagonist, phentolamine. Together, these results suggest that the transplantation of adrenal medullary tissue into the subarachnoid space of the spinal cord may provide a local source of opioid peptides and catecholamines for the reduction of chronic pain.
The impact of teacher immediacy on students' motivation: Is it the same for all students?

This study investigated the impact of teachers’ use of immediacy behaviors on students’ reported motivation to study over the course of a semester. Students’ state and trait motivation to study for a class was measured at three points during a semester. Reports of teachers’ use of verbal and nonverbal immediacy were collected at two points in a semester. It was hypothesized that not all students would respond similarly to a teacher low in immediacy. Support was found for this hypothesis. Students beginning the semester with either low or moderate state motivation to study were found to have increased levels of motivation later in the semester when exposed to a highly immediate teacher. Students beginning the semester with high motivation maintained high motivation regardless of the level of immediacy they reported their teacher of having.