cssi/SciSciGPT-SciSciNet huggingface dataset:
Angiotensin converting enzyme and kininase-II-like activities in cultured valvular interstitial cells of the rat heart.

Objective: The function of angiotensin converting enzyme (ACE) at cell sites of high collagen turnover, such as heart valves, is uncertain. The aim of this study was to assess ACE and kininase-II-like activities and collagen turnover in cultured valvular interstitial cells of the adult rat heart. Methods: The valvular interstitial cell phenotype was determined by immunolabelling (rhodamine phalloidin, desmin, and Griffonia simplicifolia lectin), and the presence of ACE mRNA and protein was confirmed by reverse transcriptase-polymerase chain reaction analysis, ACE monoclonal antibody and in vitro autoradiography, respectively. ACE and kininase-II-like activities in valvular interstitial cells were analysed by high performance liquid chromatography. Angiotensin II (AT1) and bradykinin receptors in valvular interstitial cell membranes were examined by western immunoblotting and binding assay. Type I collagen and collagenase in valvular interstitial cell culture media were determined by elisa and zymography, respectively. Type I collagen mRNA expression in cultured valvular interstitial cells was determined by northern blot analysis and in situ hybridisation. Results: In intact valvular interstitial cells or their cell membrane we found: (1) actin microfilaments, but not desmin or lectin labelling; (2) ACE mRNA expression and binding activity; (3) conversion of angiotensin I to angiotensin II, which was completely inhibited by 50 μM lisinopril, while kininase-II-like activity exceeded ACE activity and was not inhibited by lisinopril; (4) AT1 and bradykinin receptors in valvular interstitial cell membrane preparations; (5) type I collagen mRNA expression and collagenase activity; and (6) angiotensin II induced increase in type I collagen synthesis and mRNA expression. Conclusions: Cultured valvular interstitial cells represent a non-endothelial, non-smooth-muscle cell type that expresses mRNA for ACE and type I collagen. ACE and kininase-II-like activities in valvular interstitial cells may be involved in the regulation of peptides that influence collagen turnover. Angiotensin II stimulates type I collagen synthesis and mRNA expression in these cells.
Testing new physics/couplings at the NLC

Abstract I present a brief overview of the advantages of using a consistent effective Lagrangian approach in parameterizing virtual new physics effects. I then apply the formalism to certain top-quark processes.
The Complexity of Voluntary Sustainability Standards: An Emerging Economies Perspective

While firms have historically only faced pressures to comply with government regulations, recently various non-governmental bodies such as NGOs, industry groups, and individual firms have established voluntary initiatives and standards for acceptable social and environmental conduct of firms. Firms in emerging economies are frequently pressured by their customers from developed countries to adopt one or more of these voluntary sustainability standards. However, the complexity associated with voluntary standards reduces the value of these standards not only for emerging economy firms but for the entire voluntary regulatory system. We first present a framework that classifies the different types of complexity faced by firms in emerging economies that sell to foreign customers. Second, we analyze how complexity impacts the likelihood to adopt voluntary sustainability initiatives, using the empirical setting of food safety standards. Using both survey data and interview data from export- oriented agricultural...
Quasi-concave minimization subject to linear constraints

A finite algorithm is presented for solving the quasi-concave minimization problem subject to linear constraints. The concept of an extreme point is generalized to that of an extreme facet of a polyhedron. Then a search routine is developed for the detection of an extreme facet of the feasible region relative to the polyhedron defined by the current set of cuts. After identifying an extreme facet we cut it off by a cut developed for this purpose. We call this cut the facet cut. The method is both compatible with other cutting procedures and is finite..
The Difference a Course Can Make: Preservice Teachers’ Perceptions of Efficacy in Working with Families

The primary purpose of this study was to examine the extent to which preservice teachers participating in a 16-week course in family and community relations would evidence a change in perception of the importance, feasibility, and level of preparation regarding family involvement strategies. A sample of 132 undergraduate preservice teachers was examined to quantify potential change. Study methodology included pre- and posttest administration of the Peabody Family Involvement Survey (Katz & Bauch, 1999) to both treatment (n = 78) and control groups (n = 54). Data were analyzed using paired sample tests to establish the significance of shift in ratings. Findings indicate significant growth overall in the treatment groups’ attitudes toward involving families, perceived feasibility in accomplishing these practices, and their perception of their preparation for such work. Particularly noteworthy is the extent to which subjects’ impressions of feasibility of strategies changed as a result of the intervention. R...
Calculations of heating patterns of an array of microwave interstitial antennas

The heating (temperature) distribution patterns of an array of uniformly and step-insulated interstitial antennas located in inhomogeneous tissue and cancerous regions of the human body are calculated. Specifically, the bioheat equation, which takes into account various heat exchange mechanisms such as blood flow rate, heat conduction, and metabolic heat generation, is solved using the finite difference method, and the specific absorption rate in tissue heated using an array of interstitial antennas is determined using the finite-difference-time-domain method. Numerical results that validate the computer program are presented, and the effect of varying parameters such as the blood-flow rate on the resulting heating rate and patterns is examined. Possible clinical implementation of the temperature-distribution-EM-power-deposition-pattern computer code in treatment planning is described. >
GASTRIC EMPTYING IN THE NORMAL DOG A Contrast Radiographic Technique

A total of 22 radiographic studies was made to determine comparative gastric emptying times of two different solid test meals (intact kibble food and ground kibble food mixed with barium sulfate suspension) in four mature (15-26 months) normal Beagle dogs under controlled conditions. Complete gastric emptying times of the intact kibble and ground kibble meals of a given dose (8 g/kg of dog food plus 5-7 ml/kg of the contrast agent) ranged from five to ten hours (7.6 ± 1.98 hours with intact kibble meal and 7.0 ± 1.86 hours with ground kibble meal). Feeding a halfdose of ground kibble meal (4 g/kg of dog food plus 3.5 ml/kg of the contrast agent) resulted in complete gastric emptying times of four to six hours (4.7 ± 0.67 hours). Individual dogs had repeatable gastric emptying times although the times varied among different dogs.
Mechanisms of Remote Tropical Surface Warming during El Niño

Abstract The authors demonstrate through atmospheric general circulation model (the Community Climate Model version 3.10) simulations of the 1997/98 El Nino that the observed “remote” (i.e., outside the Pacific) tropical land and ocean surface warming appearing a few months after the peak of the El Nino event is causally linked to the Tropics-wide warming of the troposphere resulting from increased atmospheric heating in the Pacific, with the latter acting as a conduit for the former. Unlike surface temperature, the surface flux behavior in the remote Tropics in response to El Nino is complex, with sizable spatial variation and compensation between individual flux components; this complexity suggests a more fundamental control (i.e., tropospheric temperature) for the remote tropical surface warming. Over the remote oceans, latent heat flux acting through boundary layer humidity variations is the important regulator linking the surface warming in the model simulations to the tropospheric warming over the r...
Theories of solar eruptions: a review

Abstract This review highlights current theoretical research on eruptive phenomena in the solar atmosphere. We start by looking back upon the early theories and their development. Any theory and model of solar eruptions must explain two key aspects of eruption physics. The first aspect concerns the original cause of the eruption and the second pertains to the nature of the morphological features that form during its evolution. Those features include rapid ejection of large-scale magnetic flux and plasma into interplanetary space, and the separating of ribbons of H α emission on the solar disk joined by a rising arcade of soft X-ray and H α loops, with hard X-ray emission at their summits and feet. We intercompare relevant theories and models by discussing their advantages as well as by pointing out important aspects that need improvement.
Contextualizing Nature of Science Instruction in Socioscientific Issues

The purpose of this study was to investigate the effects of two learning contexts for explicit-reflective nature of science (NOS) instruction, socioscientific issues (SSI) driven and content driven, on student NOS conceptions. Four classes of 11th and 12th grade anatomy and physiology students participated. Two classes experienced a curricular sequence organized around SSI (the SSI group), and two classes experienced a content-based sequence (the Content group). An open-ended NOS questionnaire was administered to both groups at the beginning and end of the school year and analyzed to generate student profiles. Quantitative analyses were performed to compare pre-instruction NOS conceptions between groups as well as pre to post changes within groups and between groups. Both SSI and Content groups showed significant gains in most NOS themes, but between-group gains were not significantly different. Qualitative analysis of post-instruction responses, however, revealed that students in the SSI group tended to ...
Alteration of the hydrodynamic properties of hyaluronate solutions by corticosterone

Abstract Experiments were performed to find out if there were any physiochemical basis for certain actions of anti-inflammatory steroids in connective tissue ground substance which contains hyaluronate. Hydrodynamic properties of hyaluronate solutions in the presence and absence of corticosterone were studied. At 65 μm/100 ml, corticosterone: (1) increases the rate of buffer flow through hyaluronate solutions; (2) changes the rheological character of hyaluronate solutions from dilatant to thixotropic and (3) increases the viscosity of hyaluronate solutions. Gel chromatography of solutions of hyaluronate and steroids demonstrated the existence of hyaluronate-steroid complexes. The binding capacity of hyaluronate for the anti-inflammatory steroids, cortisol and corticosterone was greater than its binding capacity for progesterone. Hyaluronate-steroid complex was isolated by gel chromatography. In hyaluronate solutions (10 mg hyaluronate/100 ml), complexed corticosterone at 1.2·10 − μg/100 ml increased viscosity and caused thixotropy. These results were comparable to those obtained at the same hyaluronate concentration but with a total corticosterone concentration of 65 μg/100 ml.
A Refinement of the Michelson-Morley Experiment.

The investigation which is the subject of this paper was undertaken to test the conclusions recently drawn by Professor D. C. Miller from his repetition of the Michelson-Morley experiment. Professor Miller interprets his observations as indicating a motion of the sun through the ether with a velocity not less, than 200 kilometers per second in a direction about right ascension 262 degrees, declination 65 degrees. He supposes that a contraction of the apparatus in the direction of motion occurs, which, however, departs from that given by the formula of Lorentz and Fitzgerald by an amount corresponding to a velocity of about 10 kilometers per second. That is, the average shift of the interference pattern, as an arm of his interferometer is turned through 90 degrees from the direction perpendicular or parallel to the direction of the inferred drift, is such as would be expected if the velocity of the apparatus were 10 kilometers per second and no contraction occurred. In his paper in Science, April 30, 1926, he seems to have abandoned the idea that the magnitude of the indicated velocity depends on the altitude above sea level at which the observations are made. Such results as his, modifying as they would the fundamental physical concepts, require the fullest experimental confirmation.
Accidental intramuscular injection of mechlorethamine.

A 55-year-old man with chronic, active, diffuse psoriasis was accidentally given 30 mg of mechlorethamine deep into the buttock muscles. About 5 hours after the intramuscular (IM) mechlorethamine injection, 1/6 M sodium thiosulfate was infused around the intramuscular site. Although systemic responses to the mechlorethamine developed, the expected muscular and adjacent skin destruction did not occur. Instead, IM mechlorethamine induced only minimal local tenderness.
Instantiating the contingent bids model of truthful interdependent value auctions

We consider the problem of auction design with agents that have interdependent values, i.e. values that depend on each others' private signals. We adopt the contingent bids model of Dasgupta and Maskin [3], and allow agents to submit bids of the form "if player 1 bids $x for good A then I will bid $y." Our main contribution is to identify a specific linear valuation model for which there exists an efficient auction for a single item, and then extend this to provide an approximately efficient combinatorial auction with single-minded bidders. In both auction, winners and payments are computed from the fixed point of the valuation mapping defined by contingent bids. We also adopt search in order to construct a variation on the single-item auction with improved revenue. In closing, we discuss the (many) challenges in moving to more general models of interdependent valuations.
Purification and characterization of selenium-glutathione peroxidase from hamster liver.

Abstract Hamster liver glutathione peroxidase was purified to homogeneity in three chromatographic steps and with 30% yield. The purified enzyme had a specific activity of approximately 500 μmol cumene hydroperoxide reduced/min/mg of protein at 37 °C, pH 7.6, and 0.25 m m GSH. The enzyme was shown to be a tetramer of indistinguishable subunits, the molecular weight of which was approximately 23,000 as estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A single isoelectric point of 5.0 was attributed to the active enzyme. Amino acid analysis determined that selenocysteine, identified as its carboxymethyl derivative, was the only form of selenium. One residue of cysteine was found to be present in each glutathione peroxidase subunit. The presence of tryptophan was colorimetrically determined. Pseudo-first-order kinetics of inactivation of the enzyme by iodoacetate was observed at neutral pH with GSH as the only reducing agent. An optimal pH of 8.0 at 37 °C and an activation energy of 3 kcal/mol at pH 7.6 were found. A ter-uni-ping-pong mechanism was shown by the use of an integrated-rate equation. At pH 7.6, the apparent second-order rate constants for reaction of glutathione peroxidase with hydroperoxides were as follows: k 1 ( t -butyl hydroperoxide), 7.06 × 10 5 m m min −1 ; k 1 (cumene hydroperoxide), 1.04 × 10 6 m m −1 min −1 ; k 1 ( p -menthane hydroperoxide), 1.2 × 10 6 m m −1 min −1 ; k 1 (diisopropylbenzene hydroperoxide), 1.7 × 10 6 m m −1 min −1 ; k 1 (linoleic acid hydroperoxide), 2.36 × 10 6 m m −1 min −1 ; k 1 (ethyl hydroperoxide), 2.5 × 10 6 m m −1 min −1 ; and k 1 (hydrogen peroxide), 2.98 × 10 6 m m −1 min −1 . It is concluded that for bulky hydroperoxides, the more hydrophobic the substrate, the faster its reduction by glutathione peroxidase.
Perioperative morbidity and mortality in combined vs. staged approaches to carotid and coronary revascularization.

Between 1986 and 1994 we identified 57 patients who underwent carotid endarterectomy (CEA) and coronary artery bypass grafting (CABG) during the same hospitalization. Simultaneous CABG and CEA was performed in 28 patients (mean age 70.5 years, 58% male). Indications for CABG in these patients were myocardial infarction in two, crescendo angina in 19, congestive heart failure in two and left main or triple-vessel coronary artery disease noted during carotid preoperative evaluation in five. Indications for CEA were transient ischemic attack (TIA) in 12, crescendo TIA in six, cerebrovascular accident (CVA) in five, and asymptomatic stenosis in five. There were no postoperative myocardial infarctions or perioperative deaths. Two patients developed atrial fibrillation, and four patients had CVAs (two were ipsilateral to the side of CEA). Twenty-nine patients underwent staged procedures (i.e., not performed concomitantly but during the same hospitalization). Indications for CABG and CEA were comparable to those in the group undergoing simultaneous procedures. In 17 patients CEA was performed before CABG. There was a single CVA, the result of an intracerebral hemorrhage. Five of the 17 patients had a myocardial infarction and two died; one patient had first-degree heart block requiring a pacemaker. Four additional patients developed atrial fibrillation, one of whom required cardioversion. The remaining 12 patients had CABG followed by CEA. There were no CVAs, myocardial infarctions, arrhythmias, or deaths in this subgroup. These data demonstrate that the performance of simultaneous CABG and CEA procedures is associated with increased neurologic morbidity (14.3%), both ipsilateral and contralateral to the side of carotid surgery in contrast to staged CABG and CEA (3.4%). In addition, when staged carotid surgery preceded coronary revascularization in those with severe coronary artery disease, the combined cardiac complication and mortality rate was significantly higher than when coronary revascularization preceded CEA. This evidence suggests that when CABG and CEA must be performed during the same hospitalization, the procedures should be staged with CABG preceding CEA.
In situ detection of Bacillus anthracis spores using fully submersible, self-exciting, self-sensing PMN-PT/Sn piezoelectric microcantilevers.

In this study, we have demonstrated in situ, all-electrical detection of Bacillus anthracis (BA) spores using lead magnesium niobate–lead titanate/tin (PMN-PT/Sn) piezoelectric microcantilever sensors (PEMS) fabricated from PMN-PT freestanding films and electrically insulated with methyltrimethoxysilane (MTMS) coatings on the tin surface. Antibody specific to BA spore surface antigen was immobilized on the platinum electrode of the PMN-PT layer. In phosphate-buffered saline (PBS) solution, the PMN-PT/Sn PEMS exhibited quality (Q) values ranging from 50 to 75. The detection was carried out in a closed-loop flow cell with a liquid volume of 0.8 ml and a flow rate of 1 ml min−1. It was shown that one sensor, “PEMS-A” (500 µm long, 800 µm wide, with a 22 µm thick PMN-PT layer, a 20 µm thick tin layer and a 1 ± 0.5 × 10−12 g Hz−1 mass detection sensitivity) exhibited resonance frequency shifts of 2100 ± 200, 1100 ± 100 and 700 ± 100 Hz at concentrations of 20 000, 2000, and 200 spores ml−1 or 16 000, 1600, and 160 total spores, respectively. Additionally, “PEMS-B” (350 µm long, 800 µm wide, with an 8 µm thick PMN-PT layer, a 6 µm thick tin layer and a 2 ± 1 × 10−13 g Hz−1 mass detection sensitivity) exhibited resonance frequency shifts of 2400 ± 200, 1500 ± 200, 500 ± 150 and 200 ± 100 Hz at concentrations of 20 000, 2000, 100, and 45 spores ml−1 or 16 000, 1600, 80, and 36 total spores, respectively.
On the propagation of harmonic plane waves under the two-temperature theory

The propagation of harmonic plane waves in media described by the two-temperature theory of thermoelasticity (2TT) is investigated. Exact dispersion relation solutions are determined and several characterizations of the wave field are examined. High- and low-frequency results are given and special/limiting cases are also noted and discussed. In addition, critical values of the physical parameters are determined, as well as their impact on the wave fields, and the dispersion characteristics of such media are established.
Morphology of aggregates—II. Size and shape factors of carbon black aggregates from electron microscopy

Abstract Carbon black exists as primary aggregates composed of primary particles fused together. We have measured the size, anisometry and bulkincss of these primary aggregates by electron microscopy. These parameters, which define ‘structure’, show a wide spread within a given sample. Weight-average parameters are calculated with the aid of a relation between projected area and number of particles per aggregate, based on computer-simulated flocs. As expected, the average values for all three parameters are high for acetylene black and low for thermal black. Furnace blacks give intermediate values, with aggregate size being the predominant parameter related to ‘structure’, at comparable levels of particle size.
Avian and primate communication: The problem of natural categories

To negotiate effectively with the world on the basis of experience, organisms must classify past events with rules about when to lump stimulus variants into perceptual categories and when to treat them separately. In nature, tactics for evading capture vary with the predator. Appropriately, adult monkey alarm calls are specifically linked to predator category. Linkages are less precise in one-month infants but they discriminate between major predator categories. Associations become more highly specified with experience. Birds discriminate innately between conspecific and alien songs, but vocal perception is subsequently enriched by experience. Monkeys also use special processing in categorizing their own vocal repertoire. In forming perceptual categories birds and monkeys evidently use species-specific predispositions that focus attention on biologically relevant stimuli and ensure commonality in rules used by species members in perceptual analysis. Thus animals are led to share natural perceptual categories to which meaningful communicative labels can be attached.
Phenazine di-N-oxide as a carcinostatic agent.

PHENAZINE di-N-oxide has been found to be a carcinostatic agent for the Ehrlich ascites tumour. More than 90 per cent of tumour-bearing animals treated with this compound intraperitoneally survived 30 days or more, and were then free of tumours as compared with an average 13-day survival of the untreated control group. A comparison of this agent with other drugs active against this tumour reveals that 6-mercaptopurine, administered intraperitoneally1, or N-methylformamide, given orally2, extended mean survival time by 25–100 per cent, but that all animals died with ascites tumour. Other phenazine compounds, like the dye janus green B 3 have been reported to have activity against a transplanted mouse tumour, but only at toxic levels.
Accuracy and reliability of buccal bone height and thickness measurements from cone-beam computed tomography imaging.

Introduction Cone-beam computed tomography (CBCT) imaging has broadened opportunities for examining morphologic aspects of the craniofacial complex, including alveolar bone, but limitations of the technology have yet to be defined. Through the use of comparisons with direct measurements, the purpose of this study was to investigate the accuracy and reliability of buccal alveolar bone height and thickness measurements derived from CBCT images. Methods Twelve embalmed cadaver heads (5 female, 7 male; mean age: 77 years) were scanned with an i-CAT 17-19 unit (Imaging Sciences International, Hatfield, Pa) at 0.3 mm voxel size. Buccal alveolar bone height and thickness measurements of 65 teeth were made in standardized radiographic slices and compared with direct measurements made by dissection. All measurements were repeated 3 times by 2 independent raters and examined for intrarater and interrater reliability. Measurement means were compared with 2-tailed t tests. Agreement between direct and CBCT measurements was assessed by concordance correlation coefficients, Pearson correlation coefficients, and Bland-Altman plots. Results Intrarater reliability was high as were interrater correlations for all measurements (≥0.97) except CBCT buccal bone thickness (0.90). CBCT measurements did not differ significantly from direct measurements, and there was no pattern of underestimation or overestimation. The mean absolute differences were 0.30 mm in buccal bone height and 0.13 mm in buccal bone thickness with 95% limits of agreement of −0.77 to 0.81 mm, and −0.32 to 0.38 mm, respectively. Agreement between the 2 methods was higher for the measurements of buccal bone height than buccal bone thickness, as demonstrated by concordance correlation coefficients of 0.98 and 0.86, respectively. Conclusions For the protocol used in this study, CBCT can be used to quantitatively assess buccal bone height and buccal bone thickness with high precision and accuracy. Comparing the 2 sets of CBCT measurements, buccal bone height had greater reliability and agreement with direct measurements than did the buccal bone thickness measurements.
Integrating Quartus Wizard-based VHDL floating-point components into a high performance heterogeneous computing environment

One of the newest computational technologies is the high performance heterogeneous computer (HPHC) wherein dissimilar computational devices such as general purpose processors, graphics processors, field programmable gate arrays (FPGAs), etc., are used within a single platform to obtain a computational speedup. Jackson State University has a state-of-art HPHC cluster (an SRC-7), which contains traditional CPUs and reconfigurable processing units. The reconfigurable units are implemented using SRAM-based FPGAs. Currently, the off-the-shelf SRC-7 mechanism for incorporating user components (macros) does not directly support the common case of a multiple file VHDL hierarchy. This research explores a novel approach that allows multiple file VHDL floating-point kernels to be mapped onto the SRC-7. The approach facilitates the development of FPGA-based components via a hybrid technique that uses the SRC Carte compiler in conjunction with multiple file VHDL-based user macros. This research shows how Quartus Wizard-based VHDL floating-point components can be integrated into the Carte development environment.
Confocal microscopy for the analysis of siRNA delivery by polymeric nanoparticles

Clinical applications of genetic therapies, including delivery of short, interfering RNAs (siRNAs) for RNA interference (RNAi), are limited due to the difficulty of delivering nucleic acids to specific cells of interest while at the same time minimizing toxicity and immunogenicity. The use of cationic polymers to deliver nucleic acid therapeutics has the potential to address these complex issues but is currently limited by low delivery efficiencies. While cell culture studies have shown that some polymers can be used to deliver siRNAs and achieve silencing, it is still not clear what physical or chemical properties are needed to ensure that the polymers form active polymer-siRNA complexes. In this study, we used multicolor fluorescence confocal microscopy to analyze the cellular uptake of siRNAs delivered by novel propargyl glycolide polymeric nanoparticles (NPs). Delivery by these vehicles was compared to delivery by linear polyethyleneimine (LPEI) and Lipofectamine 2000 (LF2K), which are both known as effective delivery vehicles for siRNAs. Our results showed that when LF2K and LPEI were used, large quantities of siRNA were delivered rapidly, presumably overwhelming the basal levels of mRNA to initiate silencing. In contrast, our novel polymeric NPs showed delivery of siRNAs but at concentrations that were initially too low to achieve silencing. Nonetheless, the exceptionally low cytotoxicity of our NPs, and the simplicity with which they can be modified, makes them good candidates for further study to optimize their delivery profiles and, in turn, achieve efficient silencing.
Understanding the potency of stressful early life experiences on brain and body function

Early life experiences have powerful effects on the brain and body lasting throughout the entire life span and influencing brain function, behavior, and the risk for a number of systemic and mental disorders. Animal models of early life adversity are providing mechanistic insights, including glimpses into the fascinating world that is now called "epigenetics" as well as the role of naturally occurring alleles of a number of genes. These studies also provide insights into the adaptive value as well as the negative consequences, of early life stress, exposure to novelty, and poor-quality vs good-quality maternal care. Animal models begin to provide a mechanistic basis for understanding how brain development and physiological functioning is affected in children exposed to early life abuse and neglect, where there is a burgeoning literature on the consequences for physical health and emotional and cognitive development. An important goal is to identify interventions that are likely to be most effective in early life and some guidelines are provided.
Fluctuational phase-flip transitions in parametrically driven oscillators

We analyze the rates of noise-induced transitions between period-two attractors. The model investigated is an underdamped oscillator parametrically driven by a field at nearly twice the oscillator eigenfrequency. The activation energy of the transitions is analyzed as a function of frequency detuning and field amplitude scaled by the damping and nonlinearity parameters of the oscillator. Both fourth- and sixth-order nonlinearities are taken into account. The parameter ranges where the system is bistable and tristable are investigated. Explicit results are obtained in the limit of small damping, or equivalently, strong driving, including scaling near bifurcation points. @S1063-651X~98!15405-3# functional gives the exponent in the expression for the es- cape rate. An advantageous feature of period doubling in an under- damped oscillator is that it occurs for comparatively small amplitudes F of the driving force, where the nonlinearity of the oscillator is still small: the anharmonic part of the poten- tial energy is much less than the harmonic one, v 0 q 2 /2, where q is the oscillator coordinate. In this case, the quanti- ties of interest are the amplitude and phase of the vibrations at the frequency v F/2'v 0 . They vary only a little over the time ;v F1 . The corresponding dynamics is affected by Fourier components of the noise within a narrow band cen- tered at v F/2. Essentially, this means that, in the analysis of the dynamics of slow variables, the noise may be assumed to be white. A similar situation arises @12# in the problem of transitions between the stable states of forced vibrations of a resonantly driven underdamped oscillator. Below, in Sec. II, we discuss the phase portrait of a driven Duffing oscillator ~with the fourth-order nonlinearity! in the rotating frame. We then derive the properties of noise for slow variables. For low noise intensities, we formulate and solve numerically the variational problem for the activation energy of escape from period-two states. In Sec. III, explicit expressions are provided for the escape rates in the vicinities of the bifurcation points where there emerge period-two at- tractors ~a supercritical bifurcation! or unstable period-two states. The analysis in Sec. IV refers to comparatively strong driving, where the motion in slow variables is underdamped. Explicit analytical results for escape activation energies are obtained in limiting cases and compared with numerical re- sults. In Sec. V the role of sixth-order nonlinearity is dis- cussed, and the activation energies are found near bifurcation points, and also in the range where sixth-order nonlinearity is strong and the motion in slow variables is underdamped. Section VI contains concluding remarks.
Is it ethical to assign medically underserved African Americans to a usual-care control group in community-based intervention research?

The purpose of this commentary is to foster discourse regarding the need to conduct research that is scientifically rigorous while according patients the benefits and protections that they are due as human subjects. These two laudable goals can conflict with one another, leaving researchers, institutional review boards, grant application review groups, and funding agencies with the responsibility of striking an appropriate balance. For the past 14 years, our research (1) has focused on evaluating community-based interventions designed to help urban African Americans in metro Detroit live well with type 2 diabetes. Even if previous research on similar interventions has been promising, it is not possible to know a priori if a particular intervention, with these patients in this setting, will be shown to be effective. Therefore, the ideal design (from a scientific perspective) for many of these studies would be a randomized controlled trial using a usual-care control group. However, we have ethical concerns about assigning the African-American patients recruited in metro Detroit to a true usual-care control group. ### Best-known care control groups. A well-known type of control group involves comparing a new medication or procedure with the best medical care known (also known as current standard of care). The Diabetes Control and Complications Trial provides a good example of this type of control group (2). To test the glucose hypothesis, patients were randomized to either an intensive treatment intervention group or a “best-known care” (at the time of the study) control group. This type of control group differs from a usual-care control group in two very important respects. First, usual care in diabetes, particularly for medically underserved populations, is likely to be suboptimal when compared with best-known care (3). Second, in the Diabetes Control and Complications Trial, the diabetes care received by patients in the control group was precisely defined and under the …
Pharmacotherapy in pediatric obesity: Current agents and future directions

Childhood obesity is emerging as a major public health threat, with adverse implications on the health of individuals and long-term costs to society. Family-based lifestyle interventions with behavioral modification, diet and exercise form the mainstay of treatment. Pharmacologic treatment may be considered in selected subjects, especially in the presence of significant and severe comorbidities, when lifestyle intervention has failed to achieve weight reduction. Orlistat and sibutramine are FDA-approved for treatment of pediatric obesity; metformin may be considered in the presence of clinically significant insulin resistance. Evidence is lacking on the appropriate duration of medical therapy and optimal combination with lifestyle intervention. Lack of coverage of medications by insurance and high out-of-pocket costs may be limiting factors to some families. Adverse effects necessitate careful monitoring and may lead to discontinuation of medication. Pharmacologic agents with novel mechanisms of action offer hope of improved efficacy, tolerability and safety.
Thermally activated vortex nucleation as a function of thickness in submicron patterned permalloy thin films

Arrays of submicron patterned magnetic thin films often show tails in their hysteresis loops, which are usually attributed to either the coercivity distribution in the array or vortex formation/domain wall trapping in individual bits. In arrays of submicron-sized elliptical patterned bits, the tails can appear at less than the critical thickness for vortex formation, suggesting that vortices are unlikely. Thermal fluctuations, however, allow small magnetic systems to sample magnetic states that are normally inaccessible at zero temperature, which can result in different switching processes than would be expected based on zero-temperature simulations. In order to study the effect of thermal fluctuations on switching processes, arrays of submicron patterned magnetic films of different sizes and over a range of thickness were measured using the magnetooptic Kerr effect (MOKE) and compared with Langevin micromagnetic simulations. The comparison indicates that the presence of hysteresis loop tails in arrays of patterned bits is a result of vortex formation in individual bits.
Progression of damage caused by temperature cycling on a large die in a molded plastic package

Large silicon chips in molded plastic packages suffer physical damage to top-surface regions when subjected to repetitive thermal excursions. It is shown that a delamination between the molding compound and the die surface, progressing inward from a crack in the molding compound at a die corner, can enter an aluminum film through a crack in the passivation glass at an edge, travel through the metal, and exit at the opposite edge. This permits migration of glass and metal inward from corner regions. It is pointed out that reduced susceptibility to this effect may be obtained through the use of tougher metal, thicker passivation glass in lower metal edge corners, and tougher glass. A silicon integrated circuit chip approximately 250*290 mils in a 52-lead PLCC (plastic leaded chip carrier) was used as a test vehicle. Temperature and thermal shock cycling, from as low as -65 degrees C to +150 degrees C and for as many as 2000 cycles was performed. >
Histoplasmosis: a Clinical and Laboratory Update

Infection with Histoplasma capsulatum occurs commonly in areas in the Midwestern United States and Central America, but symptomatic disease requiring medical care is manifest in very few patients. The extent of disease depends on the number of conidia inhaled and the function of the host's cellular immune system. Pulmonary infection is the primary manifestation of histoplasmosis, varying from mild pneumonitis to severe acute respiratory distress syndrome. In those with emphysema, a chronic progressive form of histoplasmosis can ensue. Dissemination of H. capsulatum within macrophages is common and becomes symptomatic primarily in patients with defects in cellular immunity. The spectrum of disseminated infection includes acute, severe, life-threatening sepsis and chronic, slowly progressive infection. Diagnostic accuracy has improved greatly with the use of an assay for Histoplasma antigen in the urine; serology remains useful for certain forms of histoplasmosis, and culture is the ultimate confirming diagnostic test. Classically, histoplasmosis has been treated with long courses of amphotericin B. Today, amphotericin B is rarely used except for severe infection and then only for a few weeks, followed by azole therapy. Itraconazole is the azole of choice following initial amphotericin B treatment and for primary treatment of mild to moderate histoplasmosis.
Bulk nanostructured thermoelectric materials: current research and future prospects

Thermoelectrics have long been recognized as a potentially transformative energy conversion technology due to their ability to convert heat directly into electricity. Despite this potential, thermoelectric devices are not in common use because of their low efficiency, and today they are only used in niche markets where reliability and simplicity are more important than performance. However, the ability to create nanostructured thermoelectric materials has led to remarkable progress in enhancing thermoelectric properties, making it plausible that thermoelectrics could start being used in new settings in the near future. Of the various types of nanostructured materials, bulk nanostructured materials have shown the most promise for commercial use because, unlike many other nanostructured materials, they can be fabricated in large quantities and in a form that is compatible with existing thermoelectric device configurations. The first generation of these materials is currently being developed for commercialization, but creating the second generation will require a fundamental understanding of carrier transport in these complex materials which is presently lacking. In this review we introduce the principles and present status of bulk nanostructured materials, then describe some of the unanswered questions about carrier transport and how current research is addressing these questions. Finally, we discuss several research directions which could lead to the next generation of bulk nanostructured materials.
Obstructive Uropathy from Giant Inguinal Bladder and Ureteral Herniation

3 62-year-old man with a remote history of hernia repair as referred for bilateral hydronephrosis and serum creatiine of 4.9 mg/dL. Evaluation revealed long-standing obtructive voiding symptoms and a large recurrent right inuinal hernia. A Foley catheter was placed, with drainage of 00 mL. The patient’s renal function did not improve nor as there a significant diuresis. A CT cystogram revealed hat the nonreducible inguinal hernia contained almost the ntire bladder with the Foley balloon visible at the bladder eck, which was stretched into the hernia sac over the pubic ymphysis (A). Both ureters could be seen coursing into the ernia sac (B, arrows), but no bowel or other peritoneal tructures were identified within the hernia sac. Bilateral percutaneous nephrostomy tubes were placed o allow drainage and improve renal function. This slowly ed to a nadir creatinine level of 3.2 mg/dL. Antegrade tents were placed in preparation for surgical repair to aid in dentification and preservation of the ureters and prevent njury, given their extraanatomic position coursing within he hernia sac. Surgical exploration through a right inguinal incision evealed significant induration surrounding the chronic ernia sac and difficulty in isolating the spermatic cord. he sac could not be reduced through the hernia defect, so lower abdominal midline incision was made.The bladder as reduced from inside the peritoneal cavity after enlargng the hernia defect by incising the fascial edge. The floor f the inguinal canal was essentially absent, and a 15-cm 5-cm polypropylene mesh was used to reconstruct it, with second layer of Kugel mesh placed properitoneally for dded support.
Effects of methylprednisolone and the combination of α-tocopherol and selenium on arachidonic acid metabolism and lipid peroxidation in traumatized spinal cord tissue

Traumatic injury of the spinal cord leads to a series of pathological events that result in tissue necrosis and paralysis. Among the earliest biochemical reactions are hydrolysis of fatty acids from membrane phospholipids, production of biologically active eicosanoids, and peroxidation of lipids. This study examines the effect of agents purported to improve recovery following spinal cord trauma, methylprednisolone sodium succinate (MPSS) and the combination of alpha-tocopherol and selenium (Se), on the posttraumatic alterations of membrane lipid metabolism. Pretreatment with either MPSS or alpha-tocopherol and Se reduced the trauma-induced release of total FFA including arachidonate in the injured spinal cord tissue. In addition, these agents decreased the postinjury levels of prostanoids. Pretreatment with either MPSS or alpha-tocopherol and Se also completely prevented the trauma-induced loss of cholesterol while inhibiting the increase of a cholesterol peroxidation product, 25-hydroxycholesterol. These data suggest that: perturbation of membrane lipid metabolism may contribute to the tissue necrosis and functional deficit of spinal cord injury and MPSS or the combination of alpha-tocopherol and Se may protect injured spinal cord tissue, at least in part, by limiting these posttraumatic membrane lipid changes.
Trisomy of the short arm of chromosome 8: Association with translocation between chromosomes 8 and 22 46,XY,22−,t(8p22q)+

The case of a retarded child with trisomy of the short arm of chromosome 8 associated with translocation between the short arm of chromosome 8 and the long arm of chromosome 22 is reported. Balanced translocation involving the same chromosomes was present in the mother and brother of the propositus. The specific chromosomes involved in the abnormality in this family were identified by use of fluorescence microscopy with quinacrine mustard staining, autoradiography and Giemsa banding. This appears to be the first case report of this anomaly, although trisomy of the short arm of chromosome 9 has been reported previously.
Truth or Consequence.

Abstract Staffing, recruitment and retention, and staff development will become more challenging as resources shrink in community college libraries. Technical skills such as website development, systems maintenance, and the ability to support students and faculty using course management systems will become more specialized and may be found in staff other than librarians. Community college librarians are encouraged to involve themselves in continuous learning so that they can meet future needs their institutions and constituents.
Norepinephrine uptake dependent upon apparent Mg++-ATPase activity and proton transport in storage vesicles in axoplasm.

A Ca++-dependent secretion of norepinephrine ([3H]NE) was evoked in adrenergic nerve endings in rat heart ventricle slices incubated in a modified KrebsHCO3 medium containing choline C1 as the replacement for NaC1 (Ch+-Ca++). Exogenous ATP inhibited secretion and lithium ion, a known inhibitor of NE uptake dependent upon Mg++-ATPase activity in vesicles (but not ouabain) prevented the response to ATP (Bogdanski, 1983, 1986). It was suggested that vesicles attached to the axolemma recaptured[3H]NE from the extracellular fluid. This report indicates that other known inhibitors of uptake in isolated vesicles also inhibited the response to ATP in the attached vesicles. Included were two inhibitors of Mg++-ATPase activity, N-ethylmaleimide (NEM) and dicyclohexylcarbodiimide (DCCD), and the proton transporters 2,4-dinitrophenol (2,4- DNP 1.0 mM) and chlorpromazine (CPZ). Potassium ionophores (valinomycin with 2,4-DNP 0.1 mM and, nigericin) and a pH neutralizing reagent for vesicles (NH3 from ammonium sulfate in solution) were also effective. The uptake inhibitors, except 2,4-DNP, could also increase the rate of depletion of stored NE and its deamination in nonsecreting nerve endings incubated in Krebs-HCO3 (KRB) medium. Valinomycin by itself stimulated uptake in the presence of ATP. It is sugested that mechanisms of uptake and retention of NE in isolated vesicles (symposium (1982) Fed. Proc. 41:2742–2780) apply to the axoplasmic vesicles as well. Thus, the activity of Mg++-ATPase drives proton transport to establish the electrochemical gradients of H+, which drive the transport of NE. A lowering of the gradients can mobilize amines and evoke secretion. However, isolated vesicles in the presence of ATP and C1− eventually take up a sufficient number of ions to cause osmotic lysis. By contrast, exocytosis was not biochemically apparent in the model vesicular-axolemmal secretory and transmitter recovery unit.