cssi/SciSciGPT-SciSciNet huggingface dataset:
Managed care and people with disabilities: Framing the issues

A physical, cognitive, or mental disability presents significant challenges to an individual in gaining access to a coordinated program of preventive, primary, and secondary health care services. This article describes the health care needs of people with disabilities and discusses how the financial incentives in managed care may threaten access to the health care services they need to maintain their health and functional independence. We argue that despite the shortcomings of present models, managed care has the potential to improve the health care of people with disabilities. Moreover, as health plans become increasingly accountable to consumers (and begin to compete on the basis of quality), they will not be able to ignore the distinct health care needs of people with disabilities.
Cyber-Dissent and Power: Negotiating Online Boundaries in Repressitarian Regimes

The expansion of access to information and communication technologies (ICTs) has provided new political organizing tools for citizens â€” a development of particular importance for individuals living under authoritarian regimes that rely on the repression of free speech to maintain power. Such repressitarian elites exert control over citizen online communications, but it is economically counterproductive for countries hoping to engage in the 21st centuryâ€™s wired economy to crack down tightly on Internet. This article examines the struggles between maintaining openness and crackdowns in Iran, Egypt, China, and Singapore. These four countries are known to exert severe controls over free expression. However, Iran and Egypt have seen the rise of organized opposition movements despite the controls on media expression, whereas China and Singapore offer useful case studies on the economic dimensions of the balance between participating in the globally networked society and controlling citizen expression.
Hypothalamic neurosecretion and photoinduced testicular growth in the tree sparrow, Spizella arborea.

To assess the role of the hypothalamic neurosecretory system in the mechanism of photoperiodic control of testicular growth in Spizella arborea, we have examined the effect of (1) photostimulation on the density of paraldehyde-fuchsin-stainable (PAF+) material in the neurovascular zone of the median eminence, and (2) interruption of the hypothalamo-hypophysial (neurosecretory) tract on the photoperiodic testicular response. Birds were captured during midwinter and retained on 8-hr daily photoperiods several months prior to the experiment. Interruption of the neurosecretory tract was effected by a small knife fashioned from stainless steel wire; radiography was employed to facilitate stereotaxic placement of the knife assembly.
Control of transmitter release from retinal amacrine cells by Ca2+ influx and efflux

Cultured retinal amacrine cells show quantal GABAergic synaptic transmission. Voltage clamping pre- and post-synaptic cells of an isolated pair has allowed us to examine the entry and removal of Ca2+ at synaptic terminals. Brief presynaptic Ca2+ currents elicit an initial postsynaptic current that probably reflects the roughly synchronous exocytosis of docked vesicles. Prolonged Ca2+ currents elicit an additional second phase of release whose time course can greatly exceed that of the presynaptic voltage step. The time course of this second phase reflects a sustained increase in cytosolic Ca2+ and is matched closely by the activity of the presynaptic Na-Ca exchanger, as revealed by an exchange current. Eliminating the activity of the exchanger by removal of external Na+ prolongs this second phase of transmission greatly. Because transmitter release at these synapses outlasts Ca+ channel opening, Na-Ca exchange plays a significant role in shaping transmission.
Revascularization of the Circumflex Coronary Artery in the Atrioventricular Groove

Complete myocardial revascularization entails the grafting of all vessels of adequate size demonstrating occlusive arteriosclerotic vascular disease. Revascularization of the circumflex coronary artery in the atrioventricular groove has been a major surgical challenge because of the difficulty of exposing it. We discuss here our operative technique in 12 consecutive patients requiring revascularization of that segment of the circumflex coronary artery. Eleven grafts studied in the postoperative period were found to be patent, and the clinical course of the remaining patient and direct observations, including enzyme studies and periodic stress testing, have not shown any evidence of graft failure.
Reducing worst-case execution time of hybrid SPM-caches

This paper studies the Scratch-Pad Memory (SPM) allocation for a hybrid SPM and cache architecture, where an SPM and a cache memory are placed on-chip in parallel to cooperatively improve performance and/or energy efficiency. To benefit hard real-time systems, this paper proposes and evaluates four SPM allocation strategies to reduce the worst-case execution time (WCET) for hybrid SPM-caches with different complexities. These algorithms differ by whether or not they can cooperate with the cache or be aware of the WCET. Our evaluation shows that the cache-aware and WCET-oriented SPM allocation can maximally reduce the WCET with minimum or even positive impact on the average-case execution time (ACET).
Optimization and testing of mass spectral library search algorithms for compound identification

Five algorithms proposed in the literature for library search identification of unknown compounds from their low resolution mass spectra were optimized and tested by matching test spectra against reference spectra in the NIST-EPA-NIH Mass Spectral Database. The algorithms were probability-based matching (PBM), dot-product, Hertz et al. similarity index, Euclidean distance, and absolute value distance. The test set consisted of 12,592 alternate spectra of about 8000 compounds represented in the database. Most algorithms were optimized by varying their mass weighting and intensity scaling factors. Rank in the list of candidatc compounds was used as the criterion for accuracy. The best performing algorithm (75% accuracy for rank 1) was the dot-product function that measures the cosine of the angle between spectra represented as vectors. Other methods in order of performance were the Euclidean distance (72%), absolute value distance (68%) PBM (65%), and Hertz et al. (64%). Intensity scaling and mass weighting were important in the optimized algorithms with the square root of the intensity scale nearly optimal and the square or cube the best mass weighting power. Several more complex schemes also were tested, but had little effect on the results. A modest improvement in the performance of the dot-product algorithm was made by adding a term that gave additional weight to relative peak intensities for spectra with many peaks in common.
Distinctive histochemical characteristics of brain capillaries in organotypic culture.

Abstract Primary explants of newborn rat cerebellum and pia-arachnoid, 3 weeks in vitro , were compared as to reactivity of their vascular components with several relevant enzymes. Capillaries in organotypic cultures of somatic tissues not involved in or protected by the blood-brain barrier, e.g., skin and ossifying rib, were tested similarly. Cerebellar capillaries were characterized selectively by high activity of butyryl cholinesterase. No activity of this enzyme could be observed in meningeal capillaries, or in those which developed richly in skin and rib cultures. High activity of two other enzymes believed to be involved in the blood-brain barrier system in situ, alkaline phosphatase and γ-glutamyl transpeptidase, was registered in capillaries of both brain and meninges, but not in those of skin or rib cultures. As an inquiry into possible class or species differences, embryonic chicken cerebellum and somatic tissues (skin and rib) were similarly tested. Results indicate that a dichotomy exists also between avian brain and soma in regard to the marker enzyme, butyryl cholinesterase. These locally-differential enzyme manifestations appear to be inherent in the tissues, since they develop and persist in their respective sites of origin during weeks of isolation from the vascular apparatus of the organism as a whole. It is suggested that the nonspecific esterase, butyryl cholinesterase, may be involved in the regulation of capillary permeability within the brain.
Interaction theory of the electromagnetic field

An analysis of the field concept and its description in terms of field variables leads to the development of an Interaction Theory of the electromagnetic field with the following properties: (1) it is free of self-interaction terms; (2) the point charge model remains a viable conceptual element of the theory; (3) radiative reaction is fully accounted for within the framework of the theory and is not anad hoc addition as in conventional theory; (4) neither a single charged particle nor a system of interacting charged particles radiate to a mathematical sink at infinity. Radiation occurs only between and among the interacting particles. Energy and momentum are transferred only between and among the particles; (5) conventional conservation laws and forces are generalized; and (6) new conservation laws and forces appear. An application to a system of two interacting particles reveals in detail the conservation of energy, linear and angular momentum. Moreover, an intrinsic angular momentum of constant magnitude—a sort of classical helicity—appears. The significance of these results to the further development of electro-magnetic theory and quantum theory is briefly discussed.
Tuning of phase locked loop for industrial regenerative motor-drive systems

Regenerative motor-drive systems are utilized in several industrial applications that require frequent power generation back to the grid. In these applications, the standard front-end diode bridge commonly used in non-regenerative drives is replaced by an Active Front End “AFE” power converter. The main advantages of the AFE are that it can regenerate power back to the grid, and provide unity power factor operation with a very low total harmonic distortion. The phase locked loop “PLL” is one of the most critical control subsystems in any industrial regenerative motor-drive system. It provides the control of the front-end power converter an accurate knowledge of the utility angle and frequency to ensure proper operation of the whole control algorithm. In this paper, a detailed control analysis and tuning guidelines are presented for the PLL with an adaptive filter under several practical grid steady state and transient conditions.
Antibody microarrays: An evaluation of production parameters

Antibody microarrays could have an enormous impact on the functional analysis of cellular activity and regulation, especially at the level of protein expression and protein-protein interaction, and might become an invaluable tool in disease diagnostics. The array surface is bound to have a tremendous influence on the findings from such studies. Apart from the basic issue of how to attach antibodies optimally without affecting their function, it is also important that the cognate antigens, applied within a complex protein mixture, all bind to the arrayed antibodies irrespective of their enormous variety in structure. In this study, various factors in the production of antibody microarrays on glass support were analysed: the modification of the glass surface; kind and length of cross-linkers; composition and pH of the spotting buffer; blocking reagents; antibody concentration and storage procedures, in order to evaluate their effect on array performance. Altogether, data from more than 700 individual array experiments were taken into account. In addition to home-made slides, commercially available systems were also included in the analysis.
Model-Based Event-Triggered Control for Systems With Quantization and Time-Varying Network Delays

This paper combines two important control techniques for reducing communication traffic in control networks, namely, model-based networked control systems (MB-NCS) and event-triggered control. The resulting framework is used for stabilization of uncertain dynamical systems and is extended to systems subject to quantization and time-varying network delays. The use of a model of the plant in the controller node not only generalizes the zero-order-hold (ZOH) implementation in traditional event-triggered control schemes but it also provides stability thresholds that are robust to model uncertainties. The effects of quantized measurements are especially important in the selection of stabilizing thresholds. We are able to design error events based on the quantized variables that yield asymptotic stability compared to similar results in event-triggered control that consider nonquantized measurements which, in general, are not possible to use in digital computations. With respect to MB-NCS, the stability conditions presented here do not need explicit knowledge of the plant parameters as in previous work but are given only in terms of the parameters of the nominal model and some bounds in the model uncertainties. We consider the joint adverse effects of quantization and time delays and emphasize the expected tradeoff between the selection of quantization parameters and the admissible network induced delays.
A new operation with inadequate Brescia fistulae for preservation of more proximal veins

Abstract Purpose: The purpose of this study was to test the hypothesis that venous outflow of a Brescia fistula that is patent but unusable for one of a variety of reasons can provide adequate drainage to sustain a prosthetic arteriovenous graft based on the brachial artery, thus sparing more proximal veins for future access procedures. Methods: The operation consists of placement of a prosthetic graft between the brachial artery in the antecubital space and the cephalic vein at the wrist. Results: Between December 1998 and November 1999, 14 patients (eight male and six female; age range, 34 to 73 years; mean age, 51 years) underwent the operation. The original fistulae had been in place for 5 to 27 months (mean, 13 months). Thirteen grafts were patent at 30 days; the one early failure (24 days) was caused by infection. As of May 31, 2001, four grafts were being used (18 1 2 , 20, 23, and 28 months after placement) and four had been withdrawn in a functional state because of death (n = 3) or transplantation (n = 1). Primary functional patency rate with life-table analysis was 71%, 57%, 41%, and 41% at 3, 6, 9, and 12 months; secondary functional patency rate was 86%, 78%, 52%, and 52% at these same intervals. Three grafts had primary functional patencies greater than 18 months. Conclusion: Patent but unusable Brescia fistulae can provide adequate outflow to sustain arteriovenous grafts, thus sparing more proximal veins for future access procedures. The operation can extend by months or years the time during which satisfactory vascular access can be maintained in these patients, potentially increasing survival in some cases. We hope that the availability of this salvage option will encourage vascular surgeons to attempt arteriovenous fistulae at the wrist even in patients with suboptimal venous anatomy. (J Vasc Surg 2002;36:346-50.)
Complexity reduction in product design and development using Design for Six Sigma

In this paper, we examine various aspects of complexity in product design and development, and propose a Total Cost of Complexity (TCC) equation to quantify the impact of non-value-added complexity. This paper attempts to conceptually link the complexity concepts to the Design for Six Sigma (DFSS) approach and looks at DFSS project types, project structure to match with complexity reduction efforts. We also discuss the DFSS project structure requirements for complexity reduction based on broad criteria and compare other kinds of structures against it. A model for DFSS evolution in an organisation is proposed covering various stages an organisation goes through during DFSS implementation. An automobile fluid connection case study clearly illustrates the DFSS approach to reduce component complexity and quantifies the benefits using the TCC equation.
Dissociative effects of different types and amounts of nonreinforced CS exposure on avoidance extinction and the CER

Abstract Two experiments examined the effectiveness of two amounts of flooding or response-prevention on hastening avoidance response extinction and on reducing CS-produced suppression of bar-pressing for food. In Experiment 1, 20 and 30 flooding trials were both shown to be effective in hastening the extinction of a well-learned shuttlebox avoidance response. In Experiment 2, rats trained under comparable conditions to those in Experiment 1 were tested following flooding for the CER in a different apparatus. The results indicated that 30, but not 20, flooding trials were sufficient to reduce the CER. In each experiment the results of additional control groups equated with the flooded groups for nonreinforced CS exposure also revealed a dissociation between the effectiveness of this CS time control procedure in hastening avoidance response extinction and in reducing the CER. Further comparisons showed that although 30 flooding trials did reduce the CER, the same total duration of nonreinforced CS Exposure in the form of avoidance extinction trials did not. Thus the context in which CS exposure occurs may affect the dynamics of extinction of the CER. The experiments are discussed in the broader context of dissociation of various indices of fear in humans.
Activation of NF-κB in bone marrow cells of BALB/cJ mice following exposure in vivo to low doses of 137Cs γ-rays

We measured levels of NF-κB activation in bone marrow (BM) cells collected at 1 and 4 h from male BALB/cJ mice (10–12 weeks old) given a whole body dose of 0, 0.05, 0.1 and 1 Gy of 137Cs γ-rays (at the dose rate of 0.75 Gy/min). At each harvest time-point, BM cells were collected from five mice per dose of radiation. We used two methods for detecting NF-κB activation (1) the NF-κB/p65 transcription factor enzyme-linked immunosorbance assay (ELISA) and (2) immunofluorescence staining with NF-κB/p65 antibody. Results from ELISA indicated 2.0 and 2.8-fold increases in NF-κB activation in BM cells isolated at 1 h post-exposure of mice to 0.1 or 1.0 Gy. The immunofluorescence staining method showed similar results. In samples isolated 4 h post-irradiation, however, no activated NF-κB signal was found, regardless of the method of detection. The data also demonstrated that NF-κB was not activated in bone marrow cells collected either at 1 or 4 h from BALB/cJ mice exposed to a single dose of 0.05 Gy 137Cs γ-rays. Taken together, the results from our in vivo study indicate the involvement of NF-κB activation in early response to 0.1 and 1.0 Gy (but not 0.05 Gy) of 137Cs γ-rays.
Enhancement of elastic-light scattering due to the magnetization instability in ultrathin magnetic films

We have observed magnetic-field-dependent enhancements as large as a factor of 20 of the intensity of elastic-light scattering, from ultrathin magnetic films with perpendicular magnetic anisotropy. High-resolution Brillouin spectroscopy shows that this enhancement reaches its maximum at a critical field ${(H}_{\mathrm{crit}})$ where the magnetization starts to incline toward out-of-plane due to the perpendicular anisotropy. We attribute this effect to the microscopic instability due to random fluctuations of the magnetization near ${H}_{\mathrm{crit}}.$
Relationship of CRF-immunostained cells and magnocellular neurons in the paraventricular nucleus of rat hypothalamus.

Abstract The distribution of corticotropin-releasing factor (CRF), vasopressin (VP) and oxytocin (OXY) containing neurons within the magnocellular and parvocellular divisions in the paraventricular nucleus (PVN) of rat hypothalamus is described in brains from (a) normal untreated, (b) colchicine treated and (c) adrenalectomized animals. Double immunostained preparations using glucose oxidase-antiglucose oxidase (GAG) complex combined with PAP complex to visualize two antigens with contrasting colors in the same tissue sections were employed. Separate and distinct populations of cells containing the immunoreactive (ir) elements were seen. Immunostained CRF neurons present in the ventral medial portion of the posterior magnocellular division were juxtaposed to oxytocin-ir perikarya in colchicine treated and adrenalectomized animals. CRF-ir cells were for the most part concentrated in the medial parvocellular component of PVN. An intimate anatomical proximity between CRF-ir and VP-ir perikarya was evident in this medial parvocellular division in brains of adrenalectomized animals; this area is normally VP-ir poor except in the adrenalectomized rats. This extension of VP-ir cells into this CRF rich region and the very close approximation between the two cell bodies suggests potential cell to cell communication following pertubation of the brain-pituitary-adrenal axis. No evidence for the co-existence of two peptidergic systems in the same neuron was apparent in the present study.
Right ventricular pump dysfunction with acute experimental septic shock.

Right ventricular (RV) function has been poorly characterized at the onset of acute bacterial septic shock. Using a volumetric thermodilution catheter, previously validated in our laboratory, we serially measured RV function in a porcine model of acute septic shock. Six pigs (21.3 ± 0.9 kg) were instrumented and Pseudomonas aeruginosa (3.4 × 108 cfu/ml, 0.3 ml/20 kg/min) was infused. RV ejection fraction, RV volumes, cardiac output, arterial pressure, central venous pressure, and pulmonary arterial pressure were measured at baseline and at 30, 60, 120, and 240 min after starting the bacterial infusion. RV ejection fraction and stroke volume were decreased at 30 min compared to baseline (21 ± 5 vs 43 ± 5% and 14 ± 3 vs 23 ± 3 ml, respectively; P < 0.05) and remained depressed throughout the experiment. Mean arterial pressure was significantly reduced at 60, 120, and 240 min compared to baseline (P < 0.05). There was a significant increase in pulmonary vascular resistance (1771 ± 493 vs 301 ± 99 dyn-sec-cm−5 at 30 min; P < 0.05) and RV stroke work (5.7 ± 1.1 vs 2.3 ± 0.3 gm-m/beat at 30 min; P < 0.05) while no significant change in RV endiastolic volume or central venous pressure was observed. Thus, a decrease in RV pump performance was associated with an increase in afterload and no change in preload. These results suggest that severe RV pump dysfunction occurs early in acute septic shock. This was manifested by significant reductions in RV ejection fraction and increased in stroke work. This study demonstrated that thermodilution methods can successfully be used to follow changes in RV performance in the setting of acute septic shock. Serial measurements of RV function may be useful for assessing RV failure during clinical septic shock.
Review: Sleep Disturbance in Menopause

Sleep problems (i.e., insomnia) affect midlife women as they approach and pass through menopause at rates higher than at most other stages of life. The purpose of this article is to critically review what is known about insomnia (perceived poor sleep) and physiologically assessed sleep, as well as sleep-related disordered breathing (SDB), in women according to menopausal status and the role of hypothalamic-pituitary-ovarian (HPO) hormones. Self-report evidence that sleep difficulties are related to the hormonal changes of menopause is mixed. Data from studies in which sleep was physiologically measured reveal that sleep problems appear corequisite with hot flashes and sweats. Results are difficult to compare across studies because of varying methodologies in how sleep quality and patterns were assessed and how age cohorts and menopausal status were defined. The risk of SDB increases with age, although women are less susceptible at any age than men. As with men, snoring, obesity, and high blood pressure ar...
Effects of anesthesia on echocardiographic assessment of left ventricular structure and function in rats

Echocardiography is an essential diagnostic tool for accurate noninvasive assessment of cardiac structure and function in vivo. However, the use of anesthetic agents during echocardiographic studies is associated with alterations in cardiac anatomical and functional parameters. We sought to systematically compare the effects of three commonly used anesthetic agents on echocardiographic measurements of left ventricular (LV) systolic and diastolic function, LV dimensions, and LV mass in rats. Adult male Fischer 344 rats underwent echocardiographic studies under pentobarbital (PB, 25 mg/kg i.p.) (group I, n = 25), inhaled isoflurane (ISF, 1.5%) (group II, n = 25),or ketamine/xylazine (K/X, 37 mg/kg ketamine and 7 mg/kg xylazine i.p.) (group III, n = 25) anesthesia in a cross-over design. Echocardiography was also performed in an additional group of unanesthetized conscious rats (group IV, n = 5). Postmortem studies were performed to validate echocardiographic assessment of LV dimension and mass. Rats in group I exhibited significantly higher LV ejection fraction, fractional shortening, fractional area change, velocity of circumferential fiber shortening corrected for heart rate, and heart rate as compared with groups II and III. LV end-diastolic volume, end-diastolic diameter, and cross-sectional area in diastole were significantly smaller in group I compared with groups II and III. Cardiac output was significantly lower in group III compared with groups I and II. Postmortem LV mass measurements correlated well with echocardiographic estimation of LV mass for all anesthetic agents, and the correlation was best with PB anesthesia. Limited echocardiographic data obtained in conscious rats were similar to those obtained under PB anesthesia. We conclude that compared with ISF and K/X anesthesia, PB anesthesia at a lower dose yields echocardiographic LV structural and functional data similar to those obtained in conscious rats. In addition, PB anesthesia also facilitates more accurate estimation of LV mass.
Total and jet photoproduction cross sections at DESY HERA and Fermilab energies.

We present results of calculations of the total and jet photon-proton cross sections at energies of relevance to the Fermilab E683 experiment and the ZEUS and H-1 experiments at the DESY {ital ep} collider HERA. The calculations take into account the high-energy QCD structure of the photon and are performed for two different photon structure functions. We discuss how these forthcoming experiments may be able to provide important information on two major uncertainties inherent to the calculation of photoproduction cross sections in particular and in a more general context, to the nature of strong interactions. If the total photoproduction cross section is measured at E683 energies ({radical}{ital s} =16--28 GeV), it will provide a firmer value for {ital p}{sub {ital T}}{sup min}, the lower bound on the transverse momentum of outgoing jets, which signals the onset of hard scattering. At HERA energies ({radical}{ital s} up to 300 GeV), the total and jet cross sections will help determine the photon structure function better at low-{ital x} (the fractional parton momentum) values, currently a region where there are large uncertainties due to a lack of data.
Technology development for the space interferometry mission (SIM)

Optical and infrared interferometry will open new vistas for astronomy over the next decade. Space based interferometers, operating unfettered by the Earth's atmosphere, will offer the greatest scientific payoff. They also present the greatest technological challenge: laser metrology systems must perform with sub-nanometer precision; mechanical vibrations must be controlled to nanometers requiring orders of magnitude disturbance rejection; a multitude of actuators and sensors must operate flawlessly and in concert. The Interferometry Technology Program at NASA's Jet Propulsion Laboratory is addressing these challenges with a development program that plans to establish technology readiness for the Space Interferometry Mission by early in the year 2001.
Review of flow boiling and critical heat flux in microgravity

Space agencies worldwide are actively exploring the implementation of two-phase thermal management systems to support astronaut life onboard future space vehicles and planetary bases. Key motivations for these efforts are to increase the efficiency of power utilization and reduce overall weight and volume. These advantages are realized by orders of magnitude enhancement in heat transfer coefficient achieved with flow boiling and condensation compared to single-phase systems. This study will review published literature concerning two-phase flow and heat transfer in reduced gravity. Discussed are the different methods and platforms dedicated to exploring the influence of reduced gravity, including ground flow boiling experiments performed at different orientations relative to Earth gravity, as well as reduced gravity adiabatic two-phase flow, pool boiling, flow boiling and CHF experiments. Despite the extensive data and flow visualization results available in the literature, it is shown that there is a severe shortage of useful correlations, mechanistic models and computational models, which compromises readiness to adopt flow boiling in future space systems. Key recommendations are provided concerning platform, heater design, and operating conditions for future studies to expedite the deployment of two-phase thermal management in future space missions.
Automated Route Selection for Navigation

Automated vehicle navigation aids for drivers represent an area of considerable research interest. Whereas most previous work on the problem has assumed that such aids should be presented as maps (graphic output on a CRT), recent research suggests that drivers may perform better if given verbal (vocal) directions, rather than a graphic map. Furthermore, anecdotal evidence suggests that people often give directions to others by describing routes which are longer yet simpler than the ones they would normally use themselves. This paper presents an algorithm for selecting paths for travel by road. The algorithm is based on the principle that `ease of description is an important consideration in route selection. The route description is represented by a frame, and the route description cost is approximated by the number of slots in that frame. Then, total route cost is just the sum of the route length and the weighted route description cost.
Nagel on the rationality of prudence

Critique de l'argumentation utilisee par T. Nagel dans The Possibility of Altruism (Oxford, 1970) pour expliquer comment le fait de vouloir dans le futur avoir une raison d'accomplir une action peut donner une raison d'accomplir quelque autre action dans le present.
The thermal ignition time for homogeneous explosives involving two parallel reactions

Abstract An expression is derived for the thermal ignition time of a homogeneous explosive which is exothermically decomposing by two parallel Arrhenius reactions. The result involves the thermal ignition time of each reaction alone, and is expressed in terms of the hypergeometric function. Application of this analysis to the case of nitromethane ignition is illustrated.
Tidal salt marsh sediment in California, USA: Part 3. Current and historic toxicity potential of contaminants and their bioaccumulation

To assess potential health risks to benthic organisms from exposure to toxic contaminants, sediment chemistry data from five salt marshes along the coast of California were compared with threshold effects levels (TELs) and probable effects levels (PELs). As an integrated estimate of toxicity potential of multiple contaminants, mean PEL quotients (mPELQs) were used to categorize sampling stations into three groups: high (>0.5), medium (0.1-0.5) and low (<0.1). In all sediments from Stege Marsh located in San Francisco Bay, at least one contaminant exceeded PELs by up to 18-fold and mPELQs were higher than 0.7. Mean PELQs in two core sediments from eastern Stege Marsh ranged from 0.7 to 2.1, indicating that benthic organisms in Stege Marsh may have been adversely affected for several decades. To investigate bioavailability and bioaccumulation of contaminants in sediments, longjaw mudsuckers (Gillichthys mirabilis) were transplanted to six Stege Marsh stations for 60 days. Body burdens of organic contaminants clearly showed that they were readily available for benthic organisms. Measured concentrations of organic contaminants in mudsuckers were similar to estimated levels computed using a theoretical bioaccumulation potential model. Levels of PCBs and arsenic in mudsuckers were higher than screening values set as guidelines for the protection of humans and levels of PCBs and DDTs were higher than criteria for wildlife. The results of this study indicate that the levels of contaminants in Stege Marsh sediments may not fully support the well-being of benthic organisms and also may provoke adverse effects on fish-eating animals and humans through trophic transfer.
An advanced hypervelocity aerophysics facility - A ground-based flight-test range

The paper discusses a concept for a ground-based flight-test facility, a large aeroballistic range capable of launching models large enough to permit the installation of significant amounts of onboard instrumentation. The large model size would also provide thick shock/boundary layers, thus providing the opportunity to measure flow-field properties via advanced offboard diagnostics. Current fabrication technology should permit the construction of a two-stage light-gas gun capable of accelerating 20 to 25 cm diameter models to velocities on the order of 6 km/sec. An electromagnetic launcher or a ram accelerator is considered as a potential means for achieving larger model sizes and/or greater launch velocities. Possible methods for obtaining and recording data are discussed as are the test chamber and model deceleration section requirements.
Moderation and Mediation of HIV‐Prevention Interventions: Relationship Status, Intentions, and Condom Use Among College Students1

A study was conducted to compare the relative attitudinal intentional and behavioral effects of a communication skills self-efficacy intervention a technical skills self-efficacy intervention and enrollment in a control group. The researchers also explored whether relationship status affects the effectiveness of HIV risk reduction interventions. 49 male and 87 female college students of mean age 19.80 years participated. They had responded to campus advertisements recruiting volunteers for a safer sex education study involving discussion groups on HIV and condom use. 97.1% were self-reported heterosexuals. The 71% who had experienced sexual intercourse at least once were of mean age 17.12 years at first intercourse. The sexually experienced participants had a mean 5.42 sex partners over the course of their lives. 32.5% of the sexually experienced reported having sexual intercourse with more than one partner in the preceding 3 months. Students exposed to either intervention had greater condom use self-efficacy more positive condom use attitudes and stronger intentions to use condoms than did controls. At 3 months follow-up students in either intervention who were not in a steady dating relationship reported more consistent condom use than did those in the control group. However students who were in either intervention and in a relationship reported less consistent condom use relative to those in the control condition.
Effects of thrombolysis and atenolol or metoprolol on the signal-averaged electrocardiogram after acute myocardial infarction

Abstract Late potentials (LPs) detected on the signal-averaged (SA) electrocardiogram (ECG) predict arrhythmic events after acute myocardial infarction (AMI). The effect of thrombolysis on the incidence of LPs after AMI is controversial and its impact on subsequent arrhythmic events is not known. Moreover, the effects of β blockers on the SAECG have not been studied. Six hundred eighteen patients with AMI were studied; thrombolysis was given to 228 (37%). In comparison with patients treated conventionally, those receiving thrombolysis were significantly younger and more frequently male, had higher peak values of creatine kinase, a lower prevalence of non-Q-wave AMI, and a higher incidence of ventricular fibrillation in the acute phase, and more frequently received β blockers. An SAECG obtained 6 to 8 days after AMI showed LPs in 24% of patients receiving and in 25% not receiving thrombolysis (p = NS). On admission, intravenous β blockers were administered to 110 patients (18%); those receiving β blockers were younger, had lower peak values of creatine kinase and more frequently received thrombolysis. LPs were less frequently found in patients treated than in those not treated with β blockers (15 vs 27%; p = 0.007); however, this effect was found only in those with an ejection fraction ≥40%. Independent predictors of LPs by multivariate analysis were an ejection fraction
Protein and amino acid quality of meat and bone meal

The in vivo protein quality of 14 meat and bone meals (MBM) was evaluated in three chick growth assays and a 48-h excreta collection assay using conventional and cecectomized roosters. In addition, in vitro evaluation of protein quality was assessed using pepsin N digestibility (0.2, 0.002, or 0.0002% pepsin), KOH protein solubility, and multi-enzyme pH change. Crude protein, lysine, and SAA in the MBM varied from 48 to 56, 2.32 to 3.01, and 1.0 to 2.13%, respectively. Protein efficiency ratio (weight gain:protein intake) estimated from feeding chicks diets containing 9% protein from a MBM ranged from 0.61 to 2.89 and averaged 1.78. Lysine bioavailability determined by slope-ratio chick assay ranged from 43 to 89%. True amino acid digestibility and TMEn values determined in cecectomized roosters were generally lower (P < 0.05) than those determined in conventional roosters. True digestibility of amino acids (percentage) also varied among MBM, with the mean (and range) for lysine, methionine, and cystine in cecectomized birds being 81 (73 to 88), 85 (77 to 91), and 58% (37 to 72%), respectively. Pepsin N digestibility values determined using 0.002 or 0.0002% pepsin were positively correlated (P < 0.05) with lysine digestibility. Pepsin N digestibility determined using 0.2% pepsin, KOH protein solubility, and multi-enzyme pH change were not significantly correlated with in vivo protein quality. Ash content was negatively correlated (-0.80, P < 0.05) with protein efficiency ratio. These results indicated that there is substantial variation in protein quality among commercial MBM and that pepsin N digestibility and ash content are correlated with some in vivo protein quality measurements.
Image reconstruction from a limited number of projections: detection/estimation of multiple discs with unknown radii

Considers the problem of tomographic image reconstruction from a limited number of noisy projections. Maximum likelihood estimation is used to reconstruct an image of multiple discs with unknown locations and radii. An efficient algorithm is developed to tackle the computation. The algorithm is successfully applied to images containing as many as twelve discs with widely varying radii and with signal-to-noise ratio as low as 0 dB, and the number of projections used is as few as 16. Experimental results show that the approach significantly outperforms the conventional convolution back-projection method. >
Resolution of interaural time differences in the avian sound localization circuit—a modeling study

Interaural time differences (ITDs) are a main cue for sound localization and sound segregation. A dominant model to study ITD detection is the sound localization circuitry in the avian auditory brainstem. Neurons in nucleus laminaris (NL) receive auditory information from both ears via the avian cochlear nucleus magnocellularis (NM) and compare the relative timing of these inputs. Timing of these inputs is crucial, as ITDs in the microsecond range must be discriminated and encoded. We modeled ITD sensitivity of single NL neurons based on previously published data and determined the minimum resolvable ITD for neurons in NL. The minimum resolvable ITD is too large to allow for discrimination by single NL neurons of naturally occurring ITDs for very low frequencies. For high frequency NL neurons (>1 kHz) our calculated ITD resolutions fall well within the natural range of ITDs and approach values of below 10 μs. We show that different parts of the ITD tuning function offer different resolution in ITD coding, suggesting that information derived from both parts may be used for downstream processing. A place code may be used for sound location at frequencies above 500 Hz, but our data suggest the slope of the ITD tuning curve ought to be used for ITD discrimination by single NL neurons at the lowest frequencies. Our results provide an important measure of the necessary temporal window of binaural inputs for future studies on the mechanisms and development of neuronal computation of temporally precise information in this important system. In particular, our data establish the temporal precision needed for conduction time regulation along NM axons.
Full chip leakage-estimation considering power supply and temperature variations

Leakage power is emerging as a key design challenge in current and future CMOS designs. Since leakage is critically dependent on operating temperature and power supply, we present a full chip leakage estimation technique which accurately accounts for power supply and temperature variations. State of the art techniques are used to compute the thermal and power supply profile of the entire chip. Closed-form models are presented which relate leakage to temperature and VDD variations. These models coupled with the thermal and VDD profile are used to generate an accurate full chip leakage estimation technique considering environmental variations. The results of this approach are demonstrated on large-scale industrial designs.
Differential kinetics of α-[11C]methyl-l-tryptophan on PET in low-grade brain tumors

Increased tryptophan metabolism via the kynurenine pathway is a major mechanism of tumor immuno-resistance. α-[(11)C]Methyl-L: -tryptophan (AMT) is a positron emission tomography (PET) tracer for tryptophan catabolism, and increased AMT uptake has been demonstrated in brain tumors. In this study we evaluated the use of AMT PET for detection of low-grade gliomas and glioneuronal tumors, and determined if kinetic parameters of AMT uptake can differentiate among tumor types. AMT PET images were obtained in 23 patients with newly diagnosed low-grade brain tumors (WHO grade II gliomas and WHO grade I dysembryoplastic neuroepithelial tumors [DNETs]). Kinetic variables, including the unidirectional uptake rate (K-complex) and volume of distribution (VD; which characterizes tracer transport), were measured using a graphical approach from tumor dynamic PET and blood-input data, and metabolic rates ([Formula: see text]) were also calculated. These values as well as tumor/cortex ratios were compared across tumor types. AMT PET showed increased tumor/cortex K-complex (n = 16) and/or VD ratios (n = 15) in 21/23 patients (91%), including 11/13 tumors with no gadolinium enhancement on MRI. No increases in AMT were seen in an oligodendroglioma and a DNET. Astrocytomas and oligoastrocytomas showed higher [Formula: see text] tumor/cortex ratios (1.66 ± 0.46) than oligodendrogliomas (0.96 ± 0.21; P = 0.001) and DNETs (0.75 ± 0.39; P < 0.001). These results demonstrate that AMT PET identifies most low-grade gliomas and DNETs by high uptake, even if these tumors are not contrast-enhancing on MRI. Kinetic analysis of AMT uptake shows significantly higher tumor/cortex tryptophan metabolic ratios in astrocytomas and oligoastrocytomas in comparison with oligodendrogliomas and DNETs.
Allometric determination of tree growth in a CO2‐enriched sweetgum stand

Summary • In a free-air CO 2 enrichment (FACE) study, above-ground growth of Liquidambar styraciflua (sweetgum) trees was measured in a closed-canopy stand to test hypotheses about long-term effects of rising [CO 2 ] in a deciduous forest. • Allometric relationships were established between above-ground dry mass and basal area, height, taper and wood density for all trees in the 314-m 2 plots. Leaf area index was calculated from leaf litter mass. • In the first year of exposure, elevated [CO 2 ] stimulated stand-level aboveground dry matter increment by 33%, but in the second year the growth stimulation was reduced to 15% and was no longer statistically significant. Leaf area index was not affected by CO 2 enrichment in either year. • These results indicate that large trees that are no longer in an exponential growth phase retain the capacity to respond to elevated [CO 2 ]. The combined 2-yr response of a 24% increase in growth per unit leaf area is consistent with predictions from earlier studies. A longer-term data set is needed to resolve the reason for different responses in the 2 years.
Factor-graph-based soft self-iterative equalizer for multipath channels

We consider factor-graph-based soft self-iterative equalization in wireless multipath channels. Since factor graphs are able to characterize multipath channels to per-path level, the corresponding soft self-iterative equalizer possesses reduced computational complexity in sparse multipath channels. The performance of the considered self-iterative equalizer is analyzed in both single-antenna and multiple-antenna multipath channels. When factor graphs of multipath channels have no cycles or mild cycle conditions, the considered self-iterative equalizer can converge to optimum performance after a few iterations; but it may suffer local convergence in channels with severe cycle conditions.
Optimizing checkpoint sizes in the C3 system

The running times of many computational science applications are much longer than the mean-time-between-failures (MTBF) of current high-performance computing platforms. To run to completion, such applications must tolerate hardware failures. Checkpoint-and-rest art (CPR) is the most commonly used scheme for accomplishing this - the state of the computation is saved periodically on stable storage, and when a hardware failure is detected, the computation is restarted from the most recently saved state. Most automatic CPR, schemes in the literature can be classified as system-level checkpointing schemes because they take core-dump style snapshots of the computational state when all the processes are blocked at global barriers in the program. Unfortunately, a system that implements this style of checkpointing is tied to a particular platform amd cannot optimize the checkpointing process using application-specific knowledge. We are exploring an alternative called automatic application-level checkpointing. In our approach, programs are transformed by a pre-processor so that they become self-checkpointing and self-rest art able on any platform. In this paper, we evaluate a mechanism that utilizes application knowledge to minimize the amount of information saved in a checkpoint.
Developing a clinical proton accelerator facility: consortium-assisted technology transfer

A variable-energy medical synchrotron for accelerating protons to a prescribed energy, intensity, and beam quality has been placed in a hospital setting at Loma Linda University Medical Center for treating patients with localized cancer. The purposes of the program are control of cancer and some benign diseases and reduction of the side effects of current treatment. A major aim has been to develop a cost-effective process for exploiting the absorption characteristics of protons in tissue. The design requirements were dictated by the clinical needs of patients, physicians, and the medical center environment. These requirements increased the complexity of the system, particularly its beam delivery capability. >