cssi/SciSciGPT-SciSciNet huggingface dataset:
Insulinotropic Glucagon-like Peptide-1-mediated Activation of Non-selective Cation Currents in Insulinoma Cells Is Mimicked by Maitotoxin

Maitotoxin (MTX) activates a Ca2+-dependent non-selective cation current (ICa-NS) in insulinoma cells whose time course is identical to non-selective cation currents activated by incretin hormones such as glucagon-like peptide-1 (GLP-1), which stimulate glucose-dependent insulin secretion by activating cAMP signaling pathways. We investigated the mechanism of activation of ICa-NS in insulinoma cells using specific pharmacological reagents, and these studies further support an identity between MTX- and GLP-1-activated currents. ICa-NS is inhibited by extracellular application of genistein, econazole, and SKF 96365. This inhibition by genistein suggests that tyrosine phophorylation may play a role in the activation of ICa-NS. ICa-NS is not inhibited by incubation of cells in glucose-free solution, by extracellular tetrodotoxin, nimodipine, or tetraethylammonium, or by intracellular dialysis with 4-aminopyridine, ATP, ryanodine, or heparin. ICa-NS is also not significantly inhibited by staurosporine, which does, however, partially inhibit the MTX-induced rise of intracellular Ca2+ concentration. These effects of staurosporine suggest that protein kinase C may not be involved in the activation of ICa-NS but that it may regulate intracellular Ca2+ release. Alternatively, ICa-NS may have a small component that is carried through separate divalent cation-selective channels that are inhibited by staurosporine. ICa-NS is neither activated nor inhibited by dialysis with KF, KF + AlF3 or GTPgammaS (guanosine 5'-O-(3-thiotriphosphate)), suggesting that GTP-binding proteins do not play a major role in the activation of this current.
Hyperfine interaction of adsorbed O2− with GaAs surface atoms

Abstract EPR measurement of the hyperfine interaction between Ga nuclei and O 2 − ions adsorbed on clean GaAs is reported. The surface Ga atomic orbital concerned has an almost purely p character.
Isolation and characterization of a fatty acyl esterase from rat lung

Abstract In an effort to facilitate studies of the reaction involved in the removal of fatty acids from acyl proteins, we have synthesized an octanoic acid ester of doubly blocked serine, specifically octanoyl N-carbobenzoxy- l -serine-benzyl ester (octanoyl boc-serine), and used it as a substrate to guide the purification of an esterase from rat lung. The esterase was purified 228-fold by column chromatography on DE-52 cellulose, hydroxylapatite, octyl-Sepharose, and concanavalin A-Sepharose and by HPLC gel filtration. The final enzyme preparation ran as a single 77,000-Da band when subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis and exhibited a single symmetrical peak (sedimentation coefficient, 4.5 S) when centrifuged through a sucrose density gradient (empirical Mr, 63,000). The esterase is an acidic protein, pI 4.1, and is very active against p-nitrophenyl esters comprised of C4-C14 fatty acids; the highest specific activity (26.5μmol/min/mg) was obtained using p-nitrophenyl caprylate as substrate. The pH optimum of the lung esterase is near 8.0 and the activity on octanoyl boc-serine is maximum when 0.3% ( w v ) Myrj-52 is included in the assay medium. The activity of the esterase is not dependent on calcium ions. The enzyme does not remove acyl groups from the G-protein of vesicular stomatitis virus or the proteolipid of bovine brain. The possible role of the esterase in the metabolism of acylated proteins is considered.
Structure of medium Mach number quasi-parallel shocks: Upstream and downstream waves

The transition from steady low-Mach-number to unsteady high-Mach-number quasi-parallel shocks was investigated by performing large-scale 1D hybrid code simulations at increasing Mach numbers. It was found that only at very low Mach number shocks the steepening is limited by upstream phase-standing whistlers, as predicted by the classical theory (Tidman and Northrop, 1968). In the intermediate region of Mach numbers between 1.5 and 3.5, a very diverse behavior is observed. Backstreaming ions generate fast magnetosonic waves which dominate the upstream, with wavelengths longer than phase-standing whistlers. At increasing Mach numbers, the phase and group velocities of the dominant waves are reduced until they point back toward the shock; when there is sufficient energy flux in these waves, they lead to unsteady shock behavior and eventually to shock reformation.
Platelet factor 4 does not promote von Willebrand factor binding to human platelets

Ristocetin, protamine and Polybrene promote factor VIII:vWF binding and agglutination of formalinized platelets. It has been suggested that these polycations neutralize platelet negative surface charges and promote the attachment of VIII:vWF to platelets. Platelet factor 4 (PF4), protamine, and Polybrene inhibit heparin activity by neutralizing heparin negative charges. We tested the hypothesis that PF4, which is bound to the platelet surface after platelet activation and secretion, could promote the binding of VIII:vWF and subsequent platelet agglutination. Purified PF4 in concentrations comparable to those of ristocetin did not agglutinate formalinized platelets or induce the disappearance of VIII:vWF from the suspending plasma. Platelets were thrombin-treated in order to induce the release of PF4, and then formalinized and resuspended in normal plasma. These platelets did not agglutinate spontaneously, or at lower ristocetin concentrations than platelets that were not treated with thrombin before formalin fixation. Platelets were also activated by thrombin in the presence of EDTA to prevent surface binding of VIII:vWF or secreted PF4, and then formalinized. These platelets did not bind VIII:vWF in the presence of purified PF4. We conclude that even though PF4 binds to both polyanions and the platelet membrane, it does not promote the attachment of VIII:vWF.
An Analysis of Playa Lake Water Utilization on the Texas High Plains

ABSTRACT: This paper examines the spatial, temporal and legal aspects of playa lake water utilization on the semi-arid Texas High Plains. These small basins of interior drainage collect and briefly hold an estimated two to three million acre-feet of runoff water annually, representing from one-fourth to one-third the quantity of groundwater pumped from the dwindling Ogallala aquifer. Once considered a detriment to farming operations, there is now increased interest in using playa water more effectively. At present direct pumping is the chief method of utilization, and modification of lake bottoms to concentrate runoff and reduce evaporation is the most widespread conservation practice. The use of playa water for groundwater reacharge is hampered by as yet unsolved technical problems. For many years the question of ownership of playa water remained unsettled. The Texas Water Rights Commission now classes it as diffused surface water, which under Texas law may be used by the landowner, though some legal problems remain. For play lakes to be effectively integrated into the regional water resource it becomes imperative that all present and prospective water utilization problems be identified and resolved.
Optimal stochastic control in natural resource management: framework and examples

Abstract A framework is presented for the application of optimal control methods to natural resource problems. An expression of the optimal control problem appropriate for renewable natural resources is given and its application to Markovian systems is presented in some detail. Three general approaches are outlined for determining optimal control of infinite time horizon systems and three examples from the natural resource literature are used for illustration.
Response surface methodology to determine optimal cytokine responses in human peripheral blood mononuclear cells after smallpox vaccination

Feasibility, amount of sample aliquots, processing time and cost are critical considerations for optimizing and conducting assays for large-population based studies. Well designed statistical approaches that quickly identify optimal conditions for a given assay could assist efficient completion of the laboratory assays for such studies. For example, assessment of the profile of secreted cytokines is important in understanding the immune response after vaccination. To characterize the cytokine immune response following smallpox vaccination, PBMC obtained from recently vaccinated subjects were stimulated with varying doses of live or UV-inactivated vaccinia virus and cultured for up to 8 days. In this paper, we describe a novel statistical method to identify optimal operating conditions for length in culture and virus MOI in order to measure a panel of secreted Th1, Th2, and inflammatory cytokines. This statistical method is comprised of two components. It first identifies a subset of the possible time in culture by virus MOI combinations to be studied. It then utilizes response surface analysis techniques to predict the optimal operating conditions for the measurement of each secreted cytokine. This method was applied, and the predicted optimal combinations of length in culture and virus MOI for maximum vaccinia-specific cytokine secretion were identified. The use of the response surface methodology can be applied to the optimization of other laboratory assays; especially when the number of PBMC available limits the testing of all possible combinations of parameters.
Runway Incursion Monitoring, Detection and Alerting System (RIMDAS): A Proposed System Design for Reducing Runway Incursions

Runway incursions are a persistent problem that has resulted in some of the most catastrophic aviation accidents in history. Several systems have been proposed previously, but many of these systems are expensive and can only be justified for the busiest airports. Recent advances in wireless sensors provide a method for deploying an inexpensive detection network that can directly warn pilots of potential runway incursions. This system could prove to be an effective low-cost alternative for small to medium-sized airports who can not justify the cost of more expensive detection systems.
ECH MW-level CW transmission line components suitable for ITER

Abstract The ECH transmission lines for ITER will require performance parameters not yet entirely demonstrated in ECH systems on present magnetic fusion energy machines. The key performance requirements for the main ITER transmission lines are operation at 1 MW for pulse lengths of 400–3600 s (essentially cw) at a frequency of 170 GHz. An additional consideration for transmission line performance is the possibility that ITER will use 2 MW coaxial cavity gyrotrons currently under development by Forschungszentrum Karlsruhe (FZK) and other European Associations and European tube industry. This paper addresses the progress made by General Atomics in the various transmission line components suitable for use on ITER. ITER design documents call for a corrugated waveguide inner diameter of 63.5 mm; many components have already been fabricated in this diameter, and those that have been made in other diameters (namely 31.75 and 88.9 mm) can readily be modified to a 63.5 mm i.d. design. In some cases, water-cooling must be added to present designs to remove heat deposited during cw operation of the components.
The Contribution of Ketone Bodies to Basal and Activity-Dependent Neuronal Oxidation in Vivo:

The capacity of ketone bodies to replace glucose in support of neuronal function is unresolved. Here, we determined the contributions of glucose and ketone bodies to neocortical oxidative metabolism over a large range of brain activity in rats fasted 36 hours and infused intravenously with [2,4-13C2]-D-β-hydroxybutyrate (BHB). Three animal groups and conditions were studied: awake ex vivo, pentobarbital-induced isoelectricity ex vivo, and halothane-anesthetized in vivo, the latter data reanalyzed from a recent study. Rates of neuronal acetyl-CoA oxidation from ketone bodies (VaccoA-kbN) and pyruvate (VpdhN), and the glutamate-glutamine cycle (Vcyc) were determined by metabolic modeling of 13C label trapped in major brain amino acid pools. VacCoA-kbN increased gradually with increasing activity, as compared with the steeper change in tricarboxylic acid (TCA) cycle rate (VtcaN), supporting a decreasing percentage of neuronal ketone oxidation: ˜100% (isoelectricity), 56% (halothane anesthesia), 36% (awake) w...
Preparation of graphite fibers from polymeric fibers

The preparation of high tensile strength, high modulus of elasticity graphite fibers from polymeric fibers was investigated. Several polymeric yarns were subjected to TGA to 1000°C., the carbon yields of which indicated that polyacrylonitrile, an aromatic polyamide, and an aromatic polyimide were promising graphite precursors. Commercially available rayon-derived carbon yarns from three sources were graphitized by a continuous process. Application of stress to the carbon yarns during graphitization was found to stretch the fibers and to induce high tensile strength and high moduli in the products. The increase in tensile strength and modulus were shown to be related to the degree of orientation along the fiber axis by x-ray diffraction.
Surface area and volume measurement using radial projections

Quality evaluations in agriculture and food processing, and medical imaging often require accurate non-destructive surface area and volume measurements. A computer vision technique has been developed to achieve this task for objects with irregular shape. An imaging system was built to acquire and store images of multiple projections of the objects. Each of these images was taken at the same angular interval. Image segmentation and tracing algorithms were implemented to provide the x and y coordinates of the boundary points for each image projection. These boundary points were then used to generate a three-dimensional wire-frame model. The result of surface fitting and approximation on the wire-frame model was used to calculate the object surface area in this research. Object volume, although not covered in this research, can also be measured. Examples of agriculture and food processing applications using this vision system for surface area measurement are included in this paper. Two major challenges of this research work, system calibration and surface approximation, are discussed in this paper.
Exploring the potential of Eucalyptus for energy production in the Southern United States: Financial analysis of delivered biomass. Part I

Abstract Eucalyptus plantations in the Southern United States offer a viable feedstock for renewable bioenergy. Delivered cost of eucalypt biomass to a bioenergy facility was simulated in order to understand how key variables affect biomass delivered cost. Three production rates (16.8, 22.4 and 28.0 Mg ha −1 y −1 , dry weight basis) in two investment scenarios were compared in terms of financial analysis, to evaluate the effect of productivity and land investment on the financial indicators of the project. Delivered cost of biomass was simulated to range from $55.1 to $66.1 per delivered Mg (with freight distance of 48.3 km from plantation to biorefinery) depending on site productivity (without considering land investment) at 6% IRR. When land investment was included in the analysis, delivered biomass cost increased to range from $65.0 to $79.4 per delivered Mg depending on site productivity at 6% IRR. Conversion into cellulosic ethanol might be promising with biomass delivered cost lower than $66 Mg −1 . These delivered costs and investment analysis show that Eucalyptus plantations are a potential biomass source for bioenergy production for Southern U.S.
Where Problems and Policy Intersect: servers, problem encounters and targeted policy

In an effort to broaden and design server intervention policies more efficiently, this research examines the work location where the greatest intersection between the point of policy intervention (licenced servers) and the problem (intoxicated customers) occurs. Given the historic policy focus on servers, this research examines perceptions of all licenced servers, rather than those employed in selected settings. A six-page questionnaire was mailed to a random probability sample of all licenced servers. The sample was drawn from an official list of all individually licenced servers in the State of Indiana, USA. Bivariate and regression analyses were conducted on the 938 responses received. The analyses indicated that licenced servers' perception of their frequency of encounters with intoxicated customers is highly variable, and dependent upon numerous work location variables. The most important variable was type of establishment, particularly nightclubs and hotel or motel bars. The results suggest the need...
Some low-lying energy levels of 45Ti

Abstract Angular distributions have obtained for the 46 Ti(p, d) 45 Ti reaction at a proton bombarding energy of 26 MeV. Several new energy levels have been observed in 45 Ti up to an excitation energy of 6.33 MeV. Orbital angular momentum assignments have been made to most of the levels on the basis of DWBA calculations. Spectroscopic factors have been extracted assuming j -values suggested by the shell model.
Density functional theory study of carbon dioxide electrochemical reduction on the Fe (100) surface

Carbon dioxide electroreduction offers the possibility of producing hydrocarbon fuels using energy from renewable sources. Herein, we use density functional theory to analyze the feasibility of CO2 electroreduction on a Fe(100) surface. Experimentally, iron is nonselective for hydrocarbon formation. A simplistic analysis of low-coverage reaction intermediate energies for the paths to produce CH4 and CH3OH from CO2 suggests Fe(100) could be more active than Cu(111), currently the only metallic catalyst to show selectivity towards hydrocarbon formation. We consider a series of impediments to CO2 electroreduction on Fe(100) including O*/OH* (* denotes surface bound species) blockage of active surface sites; competitive adsorption effects of H*, CO* and C*; and iron carbide formation. Our results indicate that under CO2 electroreduction conditions, Fe(100) is predicted to be covered in C* or CO* species, blocking any C–H bond formation. Further, bulk Fe is predicted to be unstable relative to FeCx formation at potentials relevant to CO2 electroreduction conditions.
From Wasting to Obesity, Changes in Nutritional Concerns in HIV/AIDS

Optimal nutrition is an important part of human immunodeficiency virus (HIV) care; to support the immune system, limit HIV-associated complications as well as maintain better quality of life and survival. The presentation and nature of malnutrition in patients with HIV has changed dramatically over the past 30 years from predominantly a wasting syndrome to lipodystrophy and, now, frailty. Nevertheless, we continue to see all 3 presentations in patient care today. The pathogenesis of poor nutrition in HIV-infected patients depends on caloric intake, intestinal nutrient absorption/translocation, and resting energy expenditure, which are features seen in all chronic diseases.
A proposed study examining the effects of social networking use on face-to-face communication

Although social networking tools have become pervasive, few studies have examined their potential downsides. In this proposed study, we examine the effects of Facebook on the friendship-making activities of college students. We hypothesize that increased social networking use will reduce the time that students spend face to face with their friends, as well as reduce the social connectedness with their friends. We also examine whether or not how students use social networking tools has a moderating effect on the hypothesized relationships.
Immunogenicity of rhinoviruses.

SummaryUniformly successful production of rabbit rhinovirus antisera depended on production of immunogens with virus concentrations of at least 107 pfu/ml. Response in pairs of rabbits immunized with the same antigen appeared to be remarkably uniform, and maximum antibody titers were attained at 38 to 45 days after beginning a relatively simple immunization schedule (1 im + 4 iv injections). Anticellular antibody levels were usually low in comparison to rhinovirus antibody titers and such antibody could be removed easily by adsorption with suspensions of whole HeLa cells without reducing the level of antiviral antibody.The authors express their appreciation to Prudence Moeller Olsen, Marie Morasch, and Byron Doneen for valuable technical assistance.
Experiments on the sooting limits of aerodynamically-strained diffusion flames

An experimental study has been performed with axisymmetric counterflow diffusion flames to investigate the influence of aerodynamic straining on the relevant sooting limits of the lower alkanes. The limits are defined by the critical strain rate at which either soot luminosity, soot particle light-scattering, or fluorescence is negligible compared to the appropriate background signal. The critical strain rates are found to be greatest for the sooting limit based on the fluorescence signal, with those based on luminosity and light-scattering being similar. The fluorescence signal, if attributed to polycyclic aromatic precursors, yields a limit that can be interpreted as the extinction of soot precursors and is suggested to be a possible limit for identifying a completely nonsooting flame condition. The separate effects of flame temperature and fuel concentration on the critical strain rates for soot extinction have also been studied. The results are indicative of how temperature and concentration influence the soot particle inception process and they show that both are potentially important parameters. The critical strain rates display an Arrhenius temperature dependence and this dependence is similar for all alkanes considered.
Analysis of chloroplast promoters using bidirectional transcription vectors.

Spinach chloroplast RNA polymerase has been shown to efficiently terminate transcription at the threonine attenuator (thra) from Escherichia coli [7]. In this study, efficient transcription termination by the chloroplast RNA polymerase was observed at a second prokaryotic terminator, the histidine attenuator (hisa) from Salmonella typhimurium. Termination occurred regardless of the orientation of either attenuator. In higher-plant chloroplast DNA, the genes for the β subunit of the ATPase (atpB) and the large subunit of ribulose 1,5-bisphosphate carboxylase/oxygenase (rbcL) are adjacent and divergently transcribed. Bidirectional transcription vectors, containing the histidine and threonine terminators, were constructed to analyze the divergently oriented atpB and rbcL promoters. One plasmid construction, pRTT7, contained two tandem copies of the threonine attenuator (pRTT7). Two additional constructs, pRHT1 and pRHT2, each contained oppositely oriented copies of thra and hisa. A DNA fragment containing the rbcL and atpB promoters was inserted between the two terminators present in the pRTT7, pRHT1, and pRHT2 plasmids. Transcription of these recombinant DNAs by spinach chloroplast RNA polymerase resulted in discretely sized rbcL and atpB transcripts. In addition, these bidirectional transcription vectors were used to identify previously uncharacterized chloroplast promoters.
OPERATIONAL CHARACTERISTICS OF LONGER COMBINATION VEHICLES AND RELATED GEOMETRIC DESIGN ISSUES

As the size and configuration of trucks operating on public highways continues to change, how these vehicles operate needs to be better understood to accommodate them through better geometric designs or regulate them through more stringent laws and better enforcement. Longer-combination vehicles (LCVs), a group that includes Rocky Mountain doubles, turnpike doubles, and triples, fall into this category. LCVs handle and perform differently from tractor semitrailers or twin trailers because of their increased lengths and weights. These differences in handling and performance may jeopardize the safety of the LCV as well as other vehicles on the roadway. Several of the LCV's operational characteristics are believed to have an impact on transportation safety and the relationship of these characteristics to geometric design. There is a clear need to conduct additional research to further evaluate LCV operations. Several such research efforts are recommended.
Silicone breast implants: immunotoxic and epidemiologic issues.

Silicone gel implants for breast augmentation and reconstruction have been in use since 1962. Significant local complications include capsular contracture, rupture, gel "bleed", and spread of the implant material to regional lymph nodes (1-7) as well as histologic findings of foreign body granulomas in the capsular tissue and in lymph nodes (7-9). Through magnetic resonance spectroscopy and atomic emission spectroscopy, silicon compounds were found in the blood of some women with silicone breast implants; silicone and silica have also been found in liver (10). Well-publicized case reports have raised significant concerns regarding an association between implants and systemic disease. However, despite the availability of silicone implants for over 30 years, controlled epidemiological studies were not carried out until 1992. Currently available epidemiologic data are extremely limited. In part, because the majority of implants were used after 1981, the incidence of long-term problems is not yet known. In 1992, due to the unavailability of studies demonstrating the safety of implants, the U.S. Food and Drug Administration advised that silicone breast implants should be used only in reconstructive surgery and as part of clinical trials (11). This decision spurred a wave of research on the bioreactivity of silicone and clinical observations of patients with implants. Herein, we review the adverse immune effects following contact with silicone as well as the epidemiologic data available.
Global Dispersion of Current Accounts: Is the Universe Expanding?

This paper examines the global distribution of current accounts. Using a panel of more than 100 countries, the analysis establishes a set of stylized facts regarding the collective behavior of current accounts over the past four decades. In particular, we find that the global dispersion of current accounts has been steadily rising, which is qualitatively consistent with the view that ongoing financial globalization has allowed countries to maintain larger current account imbalances. However, this underlying trend is not quantitatively large enough to explain “global imbalances”—that is, the noticeable widening in external imbalances among major economies (for example, United States) seen in recent years.
Multi-voltage domain clock mesh design

This paper investigates the effectiveness of a multi-voltage clock network design that is built using the mesh topology. Unlike a clock tree, a single clock mesh that spans multiple voltage domains is infeasible due to the incompatibility of voltage levels of the clock drivers on the electrically-shorted mesh — each voltage domain requires a separate mesh. These disjoint meshes need to be matched in clock skew between the domains. In addition, the additional power dissipation of the level shifters in the logic needs to be compared against the power savings of multi-voltage domain implementation. The case study performed with the largest ISCAS'89 benchmark circuits operating at 500 MHz, 90 nm technology concludes two important results that highlight the benefits of multi-voltage clock mesh design: 1) The multi-voltage domain clock mesh can achieve 37.14% lower power with a 9 ps increase in clock skew over the single-voltage domain clock mesh, and 2) The multi-voltage domain clock mesh achieves 66 ps less skew with a 20.92% increase in power dissipation over a multi-voltage domain clock tree.
Semantic, Phonological, and Perceptual Changes Following Left and Right Intracarotid Injection (Wada) with a Low Amytal Dosage

Intracarotid injection of a low dosage of amobarbital (75 mg, 5% solution) was studied in 30 temporal lobectomy candidates while naming achromatic, incongruously, and congruously colored pictorial objects and reading real, nonsense, and embedded words. Semantic errors and phonological alexia followed the left injection, while the right injection induced visuoperceptual errors. When the contralateral hemisphere was anesthetized, the left brain formulated supraordinate categories for words and objects, while the right brain applied concrete labels. The basic language proficiency of patients influenced recovery and outcome; left temporal patients who were interictally anomic performed especially poorly after both injections. Codifying phonological and perceptual changes during the intracarotid amobarbital procedure can improve interpretations about language laterality and organization.
Blood PO2 measurements: performance of microelectrodes.

Abstract Performance of commercially available membrane covered oxygen microelectrodes was analyzed in terms of the residual current, sensitivity (amperes/mm Hg Po2 ), response time and linearity. Under idealized conditions (large fluid sample with continuous stirring) all electrodes exhibited a similar response for a particular membrane (Teflon FEP or polypropylene) and electrolyte. Residual current (Po2 = 0) was less than 1 % of the current for water equilibrated with ambient air at 38C. Response time was primarily affected by membrane thickness. There was a consistent deviation from linearity as Po2 increased toward 1 atm. In the electrodes tested it was found to be 0.5 to 5.6 % over a span of 20.9 to 70% O2. Although deviation from linearity remained constant, sensitivity increased steadily after assembly of the electrode. The standard sensitivity (i.e. the current for water in equilibrium with ambient air at 38C = S38CSTAND) provides a base line for comparative assessment of electrode performance. Arbitrary correction factors cannot be used to account for gas/water/whole blood Po2, differences. Glycerine-water mixture can be used for calibration purposes, which will give an identical reading as blood with a hematocrit of 40. Effect of hematocrit on Po2 Po2 microelectrode-calibration Electrode membrane Po2 microelectrode-performance Electrode sensitivity Standardization of blood Po2 measurements Electrode temperature
Deviations from maximum weight predict high-density lipoprotein cholesterol levels in runners: the National Runners' Health Study

Objective The inverse relationship between adiposity and high-density lipoprotein (HDL) cholesterol is well established, however, we believe that its usual representation lacks an important dimension. The purpose of this study is to test whether the relationship depends upon past weight history in addition to current weight.
Violaxanthin de-epoxidase is rate-limiting for non-photochemical quenching under subsaturating light or during chilling in Arabidopsis

In response to conditions of excess light energy, plants induce non-photochemical quenching (NPQ) as a protective mechanism to prevent over reduction of photosystem II and the generation of reactive oxygen species (ROS). The xanthophyll cycle, which contributes significantly to reversible NPQ to thermally dissipate excess absorbed light energy, involves de-epoxidation of violaxanthin and antheraxanthin to zeaxanthin in response to excess light energy. The activation of violaxanthin de-epoxidase (VDE), which catalyzes the de-epoxidation reaction, requires the generation of a light-induced, transthylakoid pH gradient. In this work, we overexpressed or repressed the expression of VDE in Arabidopsis (Arabidopsis thaliana) to examine whether VDE is rate-limiting for the induction of NPQ. Increasing VDE expression increased the de-epoxidation state of xanthophyll pigments, the rate of NPQ induction, and the level of NPQ achieved under subsaturating light. In saturating light, however, overexpression of VDE did not increase the xanthophyll pigment de-epoxidation state, the level of NPQ achieved following its initial induction, or substantially improve tolerance to high light. Only under chilling, which reduces VDE activity, did an increase in VDE expression provide slightly greater phototolerance. Repression of VDE expression impaired violaxanthin de-epoxidation, reduced the generation of NPQ, and lowered the level of NPQ achieved while increasing photosensitivity. These results demonstrate that the endogenous level of VDE is rate-limiting for NPQ in Arabidopsis under subsaturating but not saturating light and can become rate-limiting under chilling conditions. These results also show that increasing VDE expression confers greater phototolerance mainly under conditions which limit endogenous VDE activity.
Endonucleolytic activity for γ-irradiated DNA in normal and ataxia telangiectasia fibroblast cell extracts

Abstract The increased sensitivity of ataxia telangiectasia cells towards ionizing radiation may be related to their inability to incise DNA near sites of radiation-induced base damages. When compared to 3 unaffected controls, crude extracts from 5 lines of fibroblast cells derived from ataxia telangiectasia patients were capable of incising γ-irradiated DNA to the same extent as normal cells as determined in a nicking assay, using the circular replicative form of φX174. However, the types of alterations introduced into DNA by γ-irradiation could be distinguished from sites of base loss due to depurination or depyrimidination and from sites of base modification by OsO4. The specific endonuclease involved was demonstrated to be distinct from the apurinic endonuclease by its rate of temperature inactivation.
Single application of a CB1 receptor antagonist rapidly following head injury prevents long-term hyperexcitability in a rat model

Effective prophylaxis for post-traumatic epilepsy currently does not exist, and clinical trials using anticonvulsant drugs have yielded no long-term antiepileptogenic effects. We report that a single, rapid post-traumatic application of the proconvulsant cannabinoid type-1 (CB1) receptor antagonist SR141716A (Rimonabant-Acomplia) abolishes the long-term increase in seizure susceptibility caused by head injury in rats. These results indicate that, paradoxically, a seizure-enhancing drug may disrupt the epileptogenic process if applied within a short therapeutic time window.
Effects of inflammatory cytokines on the permeability of human lung microvascular endothelial cell monolayers and differential eosinophil transmigration

Abstract Background: Rhinovirus (RV) infections can result in asthma exacerbations in both adults and children. Respiratory epithelium, the primary site of RV replication, responds to the viral infection by generating a variety of cytokines and chemokines capable of promoting airway inflammation and hence might increase asthma severity. Some of these mediators might also affect the permeability of underlying vascular endothelium. Objective: We hypothesized that RV infections can promote airway inflammation and thus asthma by enhancing local vascular permeability. Methods: Confluent human lung microvascular endothelial cell (HMVEC-L) monolayers were used as an in vitro model of vascular endothelium to determine whether cytokines associated with RV-induced infections are capable of modulating endothelial cell permeability as measured by means of transendothelial electrical resistance. Recombinant cytokines and chemokines were added to confluent HMVEC-L monolayers cultured on Transwell filters, and permeability was measured as decreased electrical resistance over time. Eosinophil transendothelial migration was assessed under the same experimental conditions. Results: TNF- α , IL-1 β , and IFN- γ significantly increased HMVEC-L permeability. In contrast, GM-CSF, G-CSF, IL-8, IL-6, and RANTES had no effect. Although incubation of HMVEC-L monolayers with either TNF-α or IL-1β promoted eosinophil migration, IFN-γ had no effect, indicating that enhanced permeability alone was not sufficient for eosinophil infiltration. Conclusion: Select cytokines, generated in response to RV infection, can increase vascular permeability and might provide a mechanism by which RV infection can lead to edema, cellular infiltration, and inflammation and thus compromised airflow. (J Allergy Clin Immunol 2002;110:752-6.)
Sequence analysis of arginyl peptides by mass spectrometry.

Abstract The problem of modifying arginine-containing peptides to form volatile derivatives suitable for mass spectrometry has recently been solved in two general ways. Treatment of arginine-containing peptides with hydrazine yields ornithine residues (1, 2) while treatment with various dicarbonyl reagents results in the formation of a heterocyclic ring (1, 3). In this communication we report the use of 1,2-cyclohexanedione (CHD) in modifying arginine residues for mass spectrometry. This reagent has been shown to react quantitatively with arginine residues of proteins (Fig. 1) without significant side reactions or peptide bond cleavage (4). By combining this modification of arginine residues with acylation and permethylation (2, 5, 6) volatile compounds were obtained from several peptides. The mass spectra of these compounds combined with knowledge of the amino acid composition of the parent peptide yielded considerable sequence information for each of the arginine-containing peptides studied, including the nonapeptide bradykinin.
Lead in Maple Syrup Produced in Connecticut

The lead content of 44 maple syrup samples from 23 Connecticut producers was determined over a period of two seasons. The results ranged from 38 to 948 μg/kg and averaged 291 μg/kg. In addition, sa...
Evaluating analog-to-digital converters

Dynamic performance of an A/D converter cannot be assessed by conventional tests since they employ slowly varying inputs. In this paper, a digital computer procedure is developed to determine the presence and extent of errors due to time jitter, nonlinearity, gain, quantization, and locked bits. The procedure is based on discrete power-spectrum analysis of recorded outputs of the A/D converter using a weighted or nonweighted sine wave input. In the latter case, a discrete weighting of the recorded output must be performed before power-spectrum analysis. Outside of the narrow band containing the signal spectrum, the power spectrum corresponds to the errors in the A/D converter.Error models are suggested and implemented in a simulation program which is executed to show the power spectra for various combinations of errors. On this basis an A/D converter evaluation procedure is proposed and illustrated by an example.
Cytokine biosensors: the future of infectious disease diagnosis?

Blood carries evidence of infections, making blood analysis the first and often the best means of diagnosis. The evidence of infections is stored within memory immune cells that arise during cellul...
Assessment of acetylcholine as an optic nerve neurotransmitter in Bufo marinus.

The optic nerve and optic tectum of the marine toad, Bufo marinus, contain significant levels of acetylcholine as measured by gas chromatography-mass spectroscopy and significant activities of the enzymes choline acetyltransferase and acelylcholinesterase. Following eye enucleation. acetylcholine levels and the activities of these two enzymes fall in the denervated tectum. The decrease in acetylcholinesterase activity was shown histochemically to occur in tectal layers containing class II and class IV retinal ganglion cell terminals. These studies, in conjunction with previous biochemical and physiological experiments, provide additional evidence for the role of acetylcholine as an optic nerve neurotransmitter in the toad.
Comparing attentional bias to smoking cues in current smokers, former smokers, and non-smokers using a dot-probe task

Much evidence documents that individuals with emotional and drug-use disorders demonstrate biased attention toward stimuli associated with their disorder. This bias appears to diminish following successful treatment. Two studies examined whether current cigarette smokers show biased attention toward smoking-related images compared with non-smokers (Studies 1 and 2) and whether this bias is less pronounced in former smokers (Study 2). Attentional bias toward cigarette-related photographs was examined using the dot-probe task. Pairs of images (one smoking-related) appeared side by side for 500 ms on a computer screen prior to the presentation of a probe (an asterisk) replacing one of the photographs. Subjects struck a key as quickly as possible to indicate the probe location. Attentional bias was defined as faster reaction times when the probe replaced the smoking-related image. In both studies, current smokers displayed significantly greater attentional bias toward cigarette stimuli than did non-smokers. Former smokers in Study 2 displayed an intermediate level of bias, but did not differ significantly in bias score from either of the other groups. These results support further use of the dot-probe task as a measure of attentional bias in non-abstinent smokers and in individuals undergoing smoking cessation treatment.
Symmetry or Dynamic Consistency

In a setting with repeated experiments, where evidence about the experiments is symmetric, a decision-maker ranks bets (or acts) over their outcomes. We describe a stark modeling trade-off between symmetry of preference (indifference to permutations), dynamic consistency and ambiguity. Then, assuming that experiments are ordered in time, we outline an axiomatic model of preference that exhibits dynamic consistency and yet models learning under ambiguity.
Microchannelled hydroxyapatite components by sequential freeze drying and free pressureless spark plasma sintering

Novel freeze drying, free pressureless spark plasma sintering (FPSPS) processing sequence is developed for the production of hydroxyapatite (HAP) based microchannelled structures. The processed specimens are characterised by scanning electron microscopy, X-ray diffraction, porosity measurements and compressive tests. The compressive strength is different for different loading orientations. The compressive strength is higher in the loading direction parallel to the channel direction than the compressive strength in the loading direction perpendicular to the channel direction. Manipulation of freeze drying and FPSPS conditions should thereby enable the optimisation of the final properties of the processed porous HAP based microchannelled structures.
New FRET Methods to Study Conformational Changes in Glutamate Transporter

Crystal structures of the bacterial glutamate transporter homologue GltPh developed so far show three different states of the transporter: an outward state with HP2 open, an outward state with HP2 closed, and an inward occluded state. These crystal structures suggest that glutamate transporters undergo a series of conformational changes during substrate binding and transport. However, our previous FRET measurements on mammalian glutamate transporter EAAT3 did not report large conformation changes between outward and inward state. One possible reason is that the inward state of glutamate transporter might be relatively short lived. Thereby the majority of transporters would still be in the outward facing state, even under conditions that favor glutamate transport. Here we developed new strategies to trap the transporters in the inward state for the FRET measurement. We also used a new transition metal ion FRET method, which enables us to measure distance change within a very short range to better study the conformation change during the transport cycle. By labeling the FRET donor fluorophore and the transition metal ion acceptor at different positions of glutamate transporter EAAT3, we measured intrasubunit distance changes during Na+, glutamate binding and transport.
SPANS OF POLYMER CHAINS

Abstract The span of an N-segment chain in a given direction, e, is defined as the maximum distance between parallel planes normal to e which contain segments of the chain. We present a simple derivation of Daniel's result for the span of a random chain. We have generalized this simple derivation and have calculated: (1) 〈Xring〉, the average span of an N-segment random polymer ring; (2) 〈Xsurf.〉, the average span in the direction normal to the solution surface of an N-segment chain which is attached at one end to the surface; (3) In addition, we have obtained the exact solution of a problem treated by Hollingsworth, the calculation of 〈RHoll.〉, the average distance between the first segment and the most distant segment in an N-segment polymer chain. The results are: 〈 X r i n g 〉 = ( π N / 6 ) 1 / 2 ≅ 0.724 N 1 / 2 〈 X surf 〉 = 2 ln 2 ( π N / 6 ) 1 / 2 ≅ 1.003 N 1 / 2 〈 X Holl . 〉 = 1 2 π ( π N / 6 ) 1 / 2 ≅ 1.137 N 1 / 2 . For reference purposes we note that the average span calculated by Daniels for an N-segment polymer chain is 〈X〉 = 2(2N/3π)1/2 ≅ 0.921N1/2 and the root-mean-square end-to-end distance is 〈rN2)1/2 = N1/2. The spans of each chain configuration in the directions defined by the principal components of the square radius of gyration of the chain have been determined. The relative values of the average squares of the spans in the directions of the largest, intermediate, and smallest components of the square radius of gyration are found to be 6.7:2.2:1 in the case of the unrestricted polymer chain model. For the same model, Solc and Stockmayer obtained the following set of relative values of the ordered principal components of the square radius of gyration, 11.7:2.7:1. We have determined that the apparent difference between these two sets of relative average dimensions arises from a different segment density distribution in the different principal directions.
Improved Bend Loss Formula Verified for Optical Fiber by Simulation and Experiment

This paper presents an improved curvature loss formula for optical waveguides, which is shown to accurately predict the bend loss of both single-mode and multimode fibers. The formula expands upon a previous formula derived by Marcuse, greatly improving its accuracy for the case of multimode fiber. Also presented are the results of bent fiber simulations using the beam propagation method (BPM), and experimental measurements of bend loss. Agreement among simulation, formula and measurement support the validity of both theoretical methods. BPM simulations showed that the lowest order modes of the bent fiber were reduced to their linearly polarized constituents prior to the onset of significant bend loss. This implies that certain LP mode orientations should propagate with much lower loss than previously expected, and should impact the mode stripping ability of bent large mode area fibers, as employed in fiber lasers and amplifiers.
One Hundred and Two Problems in Mathematical Logic

This expository paper contains a list of 102 problems which, at the time of publication, are unsolved. These problems are distributed in four subdivisions of logic: model theory, proof theory and intuitionism, recursion theory, and set theory. They are written in the form of statements which we believe to be at least as likely as their negations. These should not be viewed as conjectures since, in some cases, we had no opinion as to which way the problem would go.In each case where we believe a problem did not originate with us, we made an effort to pinpoint a source. Often this was a difficult matter, based on subjective judgments. When we were unable to pinpoint a source, we left a question mark. No inference should be drawn concerning the beliefs of the originator of a problem as to which way it will go (lest the originator be us).The choice of these problems was based on five criteria. Firstly, we are only including problems which call for the truth value of a particular mathematical statement. A second criterion is the extent to which the concepts involved in the statements are concepts that are well known, well denned, and well understood, as well as having been extensively considered in the literature. A third criterion is the extent to which these problems have natural, simple and attractive formulations. A fourth criterion is the extent to which there is evidence that a real difficulty exists in finding a solution. Lastly and unavoidably, the extent to which these problems are connected with the author's research interests in mathematical logic.