cssi/SciSciGPT-SciSciNet huggingface dataset:
Scaling Analysis for the Use of Air in Place of Helium for a Heated Flow Experiment

The Modular High Temperature Gas-Cooled Reactor (MHTGR) has been chosen as a reference design for the Next Generation Nuclear Plant (NGNP) project. This reactor consists of concentric stacks of graphite blocks containing embedded fuel elements. Helium will be used as the coolant and will flow through designed coolant channels interspaced axially within the graphite blocks as well as in the gaps separating the blocks (called the bypass flow). A key phenomenon that may lead to localized hot spots in the reactor is the degradation of heat transfer effects in the bypass flow due to geometry distortions. Geometry distortions are the result of the graphite blocks being irradiated with energetic neutrons as well as coefficient of thermal expansion effects due to temperature changes. Idaho State University is studying heat transfer within the bypass flow and is developing an experiment to study the deterioration of heat transfer in the bypass flow stemming from these geometry distortions. Experimental data gathered from this project will be used to benchmark numerical codes used in the design and safety analysis of the MHTGR.Baseline MHTGR operating conditions are for a system pressure of approximately 7 MPa and a helium exit temperature from the reactor of approximately 850 °C. In place of using helium at these extreme conditions, it is our desire to perform the experiments with air entering the experiment at atmospheric pressure and temperature. Additionally, it is desirable to have an open-air system as opposed to a closed helium system. In order to quantify the impacts on temperature increase as well as pressure drop, a scaling analysis will be performed to compare the respective values from both helium and air. Important non-dimensional parameters, such as Reynolds number, non-dimensional heat flux, the acceleration factor, and non-dimensional buoyancy, will be matched for the various conditions in order to provide a similitude between the helium and air. These factors cannot be matched all at once, except by using actual conditions. The range of Reynolds number will be chosen to ensure an operating regime from the purely laminar to completely turbulent. This paper presents the results of this scaling analysis.Copyright © 2012 by ASME
THE EFFECTIVE DIELECTRIC CONSTANT OF DUST LAYERS

Abstract The electrical breakdown of a dust layer usually occurs at average electric fields which appear to be too small to initiate the breakdown. This suggests that the local electric field where breakdown occurs is somehow enhanced over that of the average field across the layer. AC dielectric measurements performed on the dust layer can be used to determine an effective static dielectric constant at a given temperature. The use of this dielectric constant in an expression for the local electric field, which combines the effects of dielectric polarization and space charge in the layer, results in predicted values of the local electric field which can be more than an order of magnitude larger than the applied field. In studies involving 11 different dust species, the dielectric constant was found to depend on temperature and layer thickness, as well as the concentration of alkali and alkaline earth metals in the dust.
Parametric study of varistor energy requirements for 500 kV series capacitors

Results are presented that show the energy absorption of a series capacitor protective varistor as a function of the most important parameters that affect energy: series capacitor impedance, power system short-circuit impedance, and varistor protective level. These results were developed from computer simulations of a simple 500 kV network model for a realistic range of parameters. Graphs of energy as a function of the three parameters provide an approximate method of determining varistor energy requirements. Two examples are given that demonstrate how to use the curves. The examples also show that the energy curves are a valid way to approximate varistor energy requirements without the use of digital simulation. The results are general because many specific series capacitor installations in actual networks can be reduced to the simple model used here. >
Increased small GTPases- the fundamental molecular mechanism underlying decreased myometrial responsiveness during quiescence

UNDERLYING DECREASED MYOMETRIAL RESPONSIVENESS DURING QUIESCENCE CLIFFORD MASON, PETER W. SWAAN, CARL P. WEINER, University of Maryland at Baltimore, Pharmaceutical Sciences, Baltimore, Maryland, University of Maryland at Baltimore, Physiology and Obstetrics, Gynecology and Reproductive Sciences, Baltimore, Maryland OBJECTIVE: The proposed mechanisms of myometrial quiescence include progesterone, fewer gap junctions, altered receptor density, etc. We showed that guinea pig (GP) myometrial quiescence was associated with increased GTPase activity. Given their pivotal role modulating secondary effector responses after receptor activation, we speculated the increased GTPase activity could provide a unifying pathway for decreased receptor mediated responses by reducing the half-life of the activated receptor complex. The object of this study was to identify the mechanism for increased myometrial GTPase activity. STUDY DESIGN: Gene profiling was performed with myometrial RNA obtained from nonpregnant, midpregnant (MP, w0.67 gestation), termpregnant (TP, w0.96 gestation), castrate and estradiol-treated castrate GPs (Affymetrix Human Genome U133A). Gene expression was normalized using Affymetrix Microarray Suite 5.0. Fold-changes in levels were calculated from the mean signals during MP and TP vs. their NP controls. Cluster analysis was performed by separating the genes into those upand down-regulated during each time period using MetaCore . Each category was further subdivided into genes specific for quiescence and activation. RESULTS: The impact of pregnancy on G-protein related mRNA was modest. Only the small GTPase Rap1b showed altered expression O2 fold (up 3! during quiescence) across gestation. But network analyses revealed that only Rab7, another small GTPase was exclusively upregulated (80%) during quiescence. In contrast, network analysis showed G-protein as the only component exclusively upregulated during late pregnancy. Estradiol mimicked the effects of pregnancy on some but not all potentially relevant G-protein family genes (including Rap1). CONCLUSION: The increased MP myometrial GTPase activity appears at least in part secondary to increased transcription of the small GTPases Rap1b and Rab7. The application of computer annotated databases allowed for the visualization of ‘pregnancy’ and ‘estradiol’ networks and universes that provide a basis for future investigation.
Toxicity of aerosol propellants on the respiratory and circulatory systems III. Influence of bronchopulmonary lesion on cardiopulmonary toxicity in the mouse

Abstract The inhalation of the following three propellants was tested in mice: trichlorofluoromethane (Fluorocarbon 11, FC11), dichlorofluoromethane (Fluorocarbon 12, FC12) and difluoroethane (Fluorocarbon 152a FC152a). There was a uniformity in nature of response of respiration and bronchopulmonary function, namely: reduction in respiratory rate, tidal volume and respiratory minute volume, decrease in pulmonary compliance and increase in pulmonary resistance. The differences between the three propellants were that FC11 caused spontaneous cardiac arrhythmias and sensitized the heart, whereas FC12 and FC152a did not. However, inhalation of FC152a caused sensitization of the heart to epinephrine in mice that had experimental bronchopulmonary lesions following intratracheal injection of papain. The bronchopulmonary system was influenced by inhalation of 1 to 2% concentration of the propellants, respiration by 2.5 to 5%, and the heart by 10 to 40%.
Analysis of Tertiary Butyl Radical + O2, Isobutene + HO2, Isobutene + OH, and Isobutene−OH Adducts + O2: A Detailed Tertiary Butyl Oxidation Mechanism

The reaction systems tert-butyl radical + O2, isobutene + HO2, isobutene + OH, and isobutene−OH adducts + O2, which are important to understanding the oxidation chemistry of tertiary butyl radical (C3C•), are analyzed. Thermochemical parameters are determined by ab initio−Mφller−Plesset (MP2(full)/6-31g(d)), complete basis set model chemistry (CBS-4 and CBS-q with MP2(full)/6-31g(d) and B3LYP/6-31g(d) optimized geometries), density functional (B3LYP/6-31g(d)), semiempirical MOPAC (PM3) molecular orbital calculations, and by group additivity estimation. Thermochemical kinetic parameters are developed for each elementary reaction path in these complex systems, and a chemical activation kinetic analysis using quantum Rice−Ramsperger−Kassel (QRRK) theory for k(E) and master equation analysis for falloff is used to calculate rate constants as a function of pressure and temperature. An elementary reaction mechanism is constructed to model experimental data for oxidation of tert-butyl radical. Calculations for l...
Ozone, acidic precipitation, and soil Mg impacts on soil and loblolly pine seedling nutrient status after three growing seasons

Recent studies have suggested that the growth of loblolly pine (Pinus taeda L.) has declined in the southeastern United States, possibly due to acidic deposition and air pollutants, especially under conditions of low nutrient availability. Consequently, the potential for individual and synergistic impacts of O3, acidic precipitation, and soil Mg status on the nutrient status of loblolly pine seedlings and soil was investigated over a 3 yr study period. Thirty-six open top chambers equipped with a rainfall exclusion/addition system were utilized to administer three levels of O3 (subambient, ambient, or twice ambient) and two acidic precipitation treatments (pH 3.8 or 5.2) to seedlings growing in 24-L plastic pots containing soil having either 35 or 15 mg kg−1 of exchangeable Mg. Each chamber contained 36 pots, and each treatment combination was replicated six times for a total of 1296 individual pots. After three seasons, throughfall and foliar nutrition data indicated that foliar leaching was not accelerated by increasing the acidity of precipitation from pH 5.2 to 3.8 and that increasing O3 did not act to exacerbate foliar leaching. Further, foliar nutrient concentrations were not significantly affected by precipitation pH or O3 treatments. Soil and soil solution data also indicate no accelerated soil leaching associated with chronic acidic precipitation. Differences in soil Mg treatments were reflected in soil solution and seedling Mg contents, but the 15 mg kg−1 soil Mg treatment was not sufficiently low enough to induce Mg deficiency in the seedlings.
The Growing Impact of Pediatric Pharmaceutical Poisoning

Objective To understand which medications, under which circumstances, are responsible for the noted increase in pediatric medication poisonings, resource use, and morbidity. Study design Patient records from 2001-2008 were obtained from the National Poison Data System of the American Association of Poison Control Centers for children aged ≤5 years evaluated in a health care facility following exposure to a potentially toxic dose of a pharmaceutical agent. Pharmaceutical agents were classified as over-the-counter or prescription and by functional category. Exposures were classified as child self-ingested the medication or as therapeutic error. For the 8-year period, emergency visits, admissions, significant injuries, and trends in these events were calculated for each substance category. Results We evaluated 453 559 children for ingestion of a single pharmaceutical product. Child self-exposure was responsible for 95% of visits. Child self-exposure to prescription products dominated the health care impact with 248 023 of the visits (55%), 41 847 admissions (76%), and 18 191 significant injuries (71%). The greatest resource use and morbidity followed self-ingestion of prescription products, particularly opioids, sedative-hypnotics, and cardiovascular agents. Conclusions Prevention efforts have proved to be inadequate in the face of rising availability of prescription medications, particularly more dangerous medications.
Site-specific enhancement and suppression of desynchronized sleep signs following cholinergic stimulation of three brainstem regions.

The behavioral effects of carbachol microinjection into the pontine, midrain and medullary reticular formation (RF) have been studied. Enhancement of electrographic desynchronized (D) sleep signs and D sleep-like behavior was specific to the pons; these paramaters were contrastingly suppressed following cholinergic stimulation of the midbrain and medullary RF. Polygraphically defined wakefulness (W) was increased from the midbrain and medulla and was characterized by stereotyped motor activity, whereas slow wave (S) sleep was reduced or eliminated when carbachol was administered into all 3 brainstem regions. In addition, as a function of the site of carbachol administation within the pons, some qualitative electrographic differences betwen carbachol-induced D sleep and the physiological D sleep state were observed. These results are consistent with the hypotheses that the pontine RF is involved in the cholinergic initiation and/or maintenance of D sleep and that the midbrain RF mediates arousal via cholinoceptive reticular cells. The hypothesis that the medullary RF plays a major role in the generation of S sleep and the atonia of D sleep is not supported by these data, but non-cholinergic mechanisms of these proposed roles remain to be investigated. Preliminary reports of these data have been published3,4.
Cellular immunity and blocking serum activity in chimeric mice.

Abstract Mice (9 CBA × T6, 6 T6, and 7 CBA) were irradiated and repopulated with foreign (BALB/c) bone marrow. Lymph node cells from 16 of 18 repopulated mice not showing signs of graft versus host disease (GVH), were cytotoxic to host type fibroblasts but not to BALB/c fibroblasts, and sera from the same mice could block lymphocyte mediated cytotoxicity. No blocking was seen with sera from three mice which had signs of GVH. LNC from the latter three mice were cytotoxic to recipient fibroblasts. It is suggested that the blocking effect detected in vitro may protect against GVH in vivo , but the relative importance of the blocking phenomenon as compared to other mechanisms is not yet settled.
Tubular atrophy in the pathogenesis of chronic kidney disease progression

The longstanding focus in chronic kidney disease (CKD) research has been on the glomerulus, which is sensible because this is where glomerular filtration occurs, and a large proportion of progressive CKD is associated with significant glomerular pathology. However, it has been known for decades that tubular atrophy is also a hallmark of CKD and that it is superior to glomerular pathology as a predictor of glomerular filtration rate decline in CKD. Nevertheless, there are vastly fewer studies that investigate the causes of tubular atrophy, and fewer still that identify potential therapeutic targets. The purpose of this review is to discuss plausible mechanisms of tubular atrophy, including tubular epithelial cell apoptosis, cell senescence, peritubular capillary rarefaction and downstream tubule ischemia, oxidative stress, atubular glomeruli, epithelial-to-mesenchymal transition, interstitial inflammation, lipotoxicity and Na+/H+ exchanger-1 inactivation. Once a a better understanding of tubular atrophy (and interstitial fibrosis) pathophysiology has been obtained, it might then be possible to consider tandem glomerular and tubular therapeutic strategies, in a manner similar to cancer chemotherapy regimens, which employ multiple drugs to simultaneously target different mechanistic pathways.
Synthesis and conformational analysis of a bridged anabasine and related compounds. A nuclear magnetic resonance spectroscopy and molecular modeling study.

Abstract The synthesis and conformational analysis of a “bridged” anabasine, 5,8,9,10,11,11a-hexahydro-6H-pyrido[2,1-f][1,6] naphthyridine ( 5 ), and related compounds are reported. Conformational assignments were made using NMR data (including coupling constants, homonuclear Overhauser effects, and 2D correlations) and the results of molecular mechanics (MM2) calculations. The tricyclic compounds have trans-quinolizidine ring fusion with a chair-shaped piperidine ring. The center ring shows a half-chair conformation for the title compound, and a half-boat shape for its 6-oxo derivative. Calculated vicinal coupling constants are in good agreement with those obtained experimentally.
Designing Programs with a Purpose: To Promote Civic Engagement for Life

Curricular and co-curricular civic engagement activities and programs are analyzed in terms of their capacity to contribute to a common set of outcomes associated with nurturing civic-minded graduates: academic knowledge, familiarity with volunteering and nonprofit sector, knowledge of social issues, communication skills, diversity skills, self-efficacy, and intentions to be involved in communities. Different programs that promote civic-mindedness, developmental models, and assessment strategies that can contribute to program enhancement are presented.
Exercise training improves left ventricular isovolumic relaxation.

Purpose: Left ventricular (LV) diastolic function is an important determinant of aerobic fitness. The purpose of this paper was to investigate the relationship between aerobic fitness and the rate and extent of isovolumic LV relaxation. Methods: Two series of experiments were performed utilizing both human and animal models. In the first series of experiments, the relationship between LV diastolic time intervals and exercise capacity was assessed in two groups of collegiate men (N = 18) with variable peak run times (Bruce protocol). In the second series of experiments, the extent of LV relaxation was examined in sedentary and exercise-trained rats (treadmill running), using an isolated, isovolumic heart preparation. Subsequent morphological assessment was also performed in rats. Results: At rest, men with greater peak treadmill time had a shorter resting LV isovolumic relaxation time (R-R interval adjusted 1000 ms) (long duration runners, 84 ± 5 ms vs short duration runners, 105 ± 7 ms, P < 0.05) despite a similar LV diastolic interval. Peak treadmill time was inversely correlated to LV isovolumic relaxation time (R-R interval adjusted 1000 ms) (r = -0.55; P < 0.02). In animal studies (N = 26), the LV pressure-volume relationship was shifted rightward in exercise-trained rats (P = 0.003). Exercise-trained rats had an increased LV inner diameter (sedentary, 5.1 ± 0.35 mm vs exercise-trained, 6.1 ± 0.28 mm, P < 0.05) and a thicker interventricular septum (sedentary, 1.52 ± 0.06 mm vs exercise-trained, 1.72 ± 0.09 mm, P <0.05). Conclusion: This study suggests that both the rate and extent of LV isovolumic relaxation is enhanced with exercise training. Further study is required to understand the interrelationship between exercise and diastolic function.
Oxidative modification of lipoic acid by HNE in Alzheimer disease brain

Alzheimer disease (AD) is an age-related neurodegenerative disease characterized by the presence of three pathological hallmarks: synapse loss, extracellular senile plaques (SP) and intracellular neurofibrillary tangles (NFTs). The major component of SP is amyloid β-peptide (Aβ), which has been shown to induce oxidative stress. The AD brain shows increased levels of lipid peroxidation products, including 4-hydroxy-2-nonenal (HNE). HNE can react covalently with Cys, His, or Lys residues on proteins, altering structure and function of the latter. In the present study we measured the levels of the HNE-modified lipoic acid in brain of subjects with AD and age-matched controls. Lipoic acid is a key co-factor for a number of proteins including pyruvate dehydrogenase and α-ketoglutarate dehydrogenase, key complexes for cellular energetics. We observed a significant decrease in the levels of HNE-lipoic acid in the AD brain compared to that of age-matched controls. To investigate this phenomenon further, the levels and activity of lipoamide dehydrogenase (LADH) were measured in AD and control brains. Additionally, LADH activities were measured after in-vitro HNE-treatment to mice brains. Both LADH levels and activities were found to be significantly reduced in AD brain compared to age-matched control. HNE-treatment also reduced the LADH activity in mice brain. These data are consistent with a two-hit hypothesis of AD: oxidative stress leads to lipid peroxidation that, in turn, causes oxidative dysfunction of key energy-related complexes in mitochondria, triggering neurodegeneration. This study is consonant with the notion that lipoic acid supplementation could be a potential treatment for the observed loss of cellular energetics in AD and potentiate the antioxidant defense system to prevent or delay the oxidative stress in and progression of this devastating dementing disorder.
Role of mouse allergens in allergic disease

Mouse allergen has long been recognized as an important cause of occupational allergy and asthma, but only recently has it been implicated in asthma and allergic diseases in community settings. Recent studies have established that mouse allergen is detectable in most US homes, with strikingly high levels in some inner cities. Inner city homes in major northeastern and midwestern US urban centers have levels as much as 100-fold higher than those found in other geographic regions. In addition, about 25% of inner city children with asthma have evidence of IgE sensitization to mouse. Several studies have shown that the combination of sensitization and exposure to higher levels of mouse allergen is associated with substantial asthma morbidity, including hospitalizations. Integrated pest management is efficacious in reducing mouse allergen levels and is recommended for sensitized patients with asthma. However, its impact on clinical outcomes has not yet been proven.
Stellar Evolution with Arbitrary Rotation Laws. III. Convective Core Overshoot and Angular Momentum Distribution

Intermingled two-dimensional hydrodynamic and two-dimensional stellar evolution calculations are presented for two 8.75 M☉ models, one nonrotating and one rotating with a zero-age main sequence surface equatorial rotational velocity of 200 km s-1. The first calculation of the rotating model was made assuming no convective core overshooting and enforcing solid-body rotation in the convective core. Hydrodynamic simulations at various stages of core hydrogen burning indicate that neither of these assumptions is true. Overshooting to a distance equivalent to about 0.35 pressure scale heights is found, and there is some evidence that the distance in terms of the pressure scale height increases slightly in later stages of core hydrogen burning. This is not a claim that the pressure scale height is a relevant parameter for determining overshooting distances. The dynamic calculations also show that the rotation rate in the convective core is approximately constant on cylinders and that the rate may be expressed as a power law in the distance from the rotation axis, as long as there is a cutoff at small distances. Two more evolutionary sequences, one rotating and one not, were calculated utilizing these results. The largest effects are produced from the overshooting and are esssentially those found by previous researchers. However, the angular momentum distribution in the interior at the end of core hydrogen burning is significantly different for this second case than for the one assuming solid-body rotation in the convective core. The primary differences are that the horizontal variation in the rotation rate is much larger and that the rotation rate near the center is much higher in the second case.
Engineering autonomic systems

The wide-spread interest in self-management reflects the disturbing fact that scaling information systems is often impaired by the burdens of management and operations. These concerns have motivated the development of technologies for self-healing, self-configuration, self-optimization, and self-protection. Regrettably, it is rare for these technologies to be deployed in production because of their hidden costs. For example, model-based approaches for configuration and optimization are powerful in laboratory demonstrations, but these approaches typically have high costs for model construction and maintenance. This talk discusses the need for a methodology for engineering autonomic systems that systematically addresses requirements, design, implementation, and assessment. The approach discussed in this talk is based on control theory, an approach that is widely used in other engineering disciplines to blend formal mathematics with practical insights to build robust systems.
The influence of filament material on radical production in hot wire chemical vapor deposition of a-Si:H

Abstract The choice of filament material has an influence on the decomposition of silane during the hot wire chemical vapor deposition of amorphous and microcrystalline silicon films. In this paper, the Si radicals produced from W, Re, Mo and Ta filament materials are probed by laser-based single photon ionization as a function of hot wire temperature. The apparent activation energy of the Si radical production in the surface reaction regime from Ta (140–180 kcal/mol) and Mo (120–160 kcal/mol) are found to be close to the corresponding Si thermal desorption energies from these surfaces, suggesting that the Si production is controlled by the desorption process from the bare metal. On the other hand, the Si activation energies from W and Re (60 kcal/mol) are lower than the related desorption energies, suggesting silicon desorption from a silicon layer formed on the surfaces. Kinetic modeling supports this desorption mechanism. In addition to the Si radical study, the corresponding film deposition is detected in situ by multiple internal reflection infrared spectroscopy, from which growth rates are estimated. The results show similar activation energies for both the growth rate and Si formation from the various filaments, implying that Si radical production and subsequent film growth are dominated by the same elementary reactions at low pressure.
Evaluation of liver fibrosis in patients with thalassemia: the important role of hyaluronic acid.

Patients with transfusion-dependent thalassemia major often develop liver fibrosis due to liver iron overload and/or hepatitis virus C (HCV) infection. Hyaluronic acid (HA) plays a prominent role in the pathogenesis of liver fibrosis and the elevation of serum HA concentration is due to either increased synthesis by inflammatory cells and hepatic stellate cells or impaired degradation by sinusoidal endothelial cells (SECs) and thus is proposed as a non-invasive biomarker of liver fibrosis either by itself and/or included in the Hepascore formula. In this study we evaluated prospectively a screening of liver fibrosis in 201 adult patients aged 19-54 years with transfusion-dependent thalassemia major, based on HA measurements. 41/201 patients were HCV-RNA (+). HA was measured with a turbidimetric assay applied on a clinical chemistry analyzer. The Hepascore was computed from the results by using the model previously published. The main results of the study showed that: a) HA levels were increased in 110/201 (55%) thalassemia patients 85.0 ± 10.3 ng/ml, ranged from 15.0 to 1495.0 μg/l, compared to 20.8 ± 7.4 μg/l reference laboratory values, p 0.324 and p>0.270, respectively). Our findings indicate that hyaluronic acid measurements contribute to the assessment of liver fibrosis in patients with thalassemia and might be helpful for further evaluation of patients with liver biopsy if this is truly needed. Furthermore, liver fibrosis in thalassemia seems to be independent from liver siderosis.
Molecular mechanisms of the microsomal mixed function oxidases and biological and pathological implications

The cytochrome P450 mixed function oxidase enzymes play a major role in the metabolism of important endogenous substrates as well as in the biotransformation of xenobiotics. The liver P450 system is the most active in metabolism of exogenous substrates. This review briefly describes the liver P450 (CYP) mixed function oxidase system with respect to its enzymatic components and functions. Electron transfer by the NADPH-P450 oxidoreductase is required for reduction of the heme of P450, necessary for binding of molecular oxygen. Binding of substrates to P450 produce substrate binding spectra. The P450 catalytic cycle is complex and rate-limiting steps are not clear. Many types of chemical reactions can be catalyzed by P450 enzymes, making this family among the most diverse catalysts known. There are multiple forms of P450s arranged into families based on structural homology. The major drug metabolizing CYPs are discussed with respect to typical substrates, inducers and inhibitors and their polymorphic forms. The composition of CYPs in humans varies considerably among individuals because of sex and age differences, the influence of diet, liver disease, presence of potential inducers and/or inhibitors. Because of such factors and CYP polymorphisms, and overlapping drug specificity, there is a large variability in the content and composition of P450 enzymes among individuals. This can result in large variations in drug metabolism by humans and often can contribute to drug-drug interactions and adverse drug reactions. Because of many of the above factors, especially CYP polymorphisms, there has been much interest in personalized medicine especially with respect to which CYPs and which of their polymorphic forms are present in order to attempt to determine what drug therapy and what dosage would reflect the best therapeutic strategy in treating individual patients.
Progressive-ratio performance maintained by drug infusions: comparison of cocaine, diethylpropion, chlorphentermine, and fenfluramine.

Cocaine, diethylpropion, chlorphentermine, and fenfluramine were compared on a drug-maintained progressive-ratio procedure in baboons. Intravenous infusions of drug were contingent on completion of a fixed-ratio response requirement (fixed number of lever-press responses) with a 3-h time-out period following each infusion. Prior to testing each dose of drug, stable self-infusion performance was first established with 0.4 mg/kg cocaine when the fixed-ratio requirement was 160. Subsequently, a test dose of drug was substituted for the standard dose of cocaine. If the dose of drug maintained a criterion level of self-infusion performance (six or more infusions per day for 2 days), the ratio requirement was systematically increased every day until the ‘breaking point’ at which the self-infusion performance fell below a criterion level (one or zero infusionsper day). Fenfluramine did not maintain criterion self-infusion performance at any dose tested (0.02–5.0 mg/kg). The dose ranges of the other drugs that maintained maximum breaking points were 1.0–5.6 mg/kg for chlorphentermine, 1.0–3.0 mg/kg for diethylpropion, and 0.1–0.4 mg/kg for cocaine. Within-animal comparison of the maximum breaking points indicated that cocaine maintained the highest breaking points, followed in order by diethylpropion, chlorphentermine, and fenfluramine. The rank ordering of these drugs with the breaking point measure corresponds well with both the results of other animal experiments on measurement of reinforcing efficacy of these drugs and with the clinical information about the human subjective effects and abuse of these drugs.
On advertising durability and product durability

This paper uses a simple two-period model to examine the behaviour of a monopolist who produces a durable good and engages in advertising that is also somewhat durable. It is found that changes in product durability and advertising durability have opposite effects on profit-maximizing output and advertising. Policy implications for antitrust and health regulation are discussed.
Invited commentary: tourism planning and traditional urban planning theory - the planner as an agent of social change.

Abstract The field of urban and regional planning is much more comprehensive in both subject matter and outcomes than is most tourism planning, as least as each is taught in higher education around the world. Tourism planning, however, draws upon a good portion of urban and regional planning methods, especially in the area known as rational planning. As such, the more narrow area of tourism planning could be considered a subfield of urban and regional planning. One major shortcoming of tourism planning is an apparent lack of attention to the normative issues of (1) how planners should plan and (2) what issues planners should focus on in their planning efforts. These questions address the complexity of data and issues that planners deal with, including questions of what data or information is collected, how it is organized, and how the information will be used to make decisions. Tourism planners could benefit from greater familiarity with these fundamental concepts of planning theory.
Off-Road Vehicle Dynamics Mobility Simulation With a Compaction Based Deformable Terrain Model

This paper discusses the terramechanics models developed to incorporate a physics-based, three dimensional deformable terrain database model with vehicle dynamics mobility simulation software. The vehicle model is contained in Chrono, a research-grade C++ based Application Programming Interface (API) that enables accurate multibody simulations. The terrain database is also contained in a C++ based API, and includes a general tire-terrain interaction model which is modular to allow for any tire model that supports the Standard Tire Interface (STI) to operate on the terrain. Furthermore, the ability to handle arbitrary, three dimensional traction element geometry allows for tracked vehicles (or vehicle hulls) to also interact with the deformable terrain. The governing equations of the terrain are based on a soil compaction model that includes both the propagation of subsoil stresses due to vehicular loads, and the resulting visco-elastic-plastic stress/strain on the affected soil volume. Non-flat, non-homogenous and non-uniform soil densities, rutting, repeated loading and strain hardening effects are all captured in the vehicle mobility response as a result of the general 3-D tire/terrain model developed. Pedo-transfer functions allow for the calculation of the soil mechanics model parameters from existing soil measurements. This terrain model runs at near real-time speed, due to parallel CPU and GPU implementation. Results that exercise the force models developed with the 3-D tire geometry are presented and discussed for a kinematically driven tire and a full vehicle simulation.Copyright © 2013 by ASME
The yield for two-photon emission from radiation of thick targets by a 109Cd-113mCd radioactive source

Abstract Lehtihet and Quarles have reported the measurement of the two-photon yield from the radiation of thick targets of Ag, Au, and Pb by a 109 Cd radioactive source which has recently been found to have a significant component of 113m Cd. This means that there was a component of energetic electrons that was not considered in the original comparison of the data to a model calculation. Also, recent measurements of thick-target double bremsstrahlung produced by an electron beam have led to the development of a new, more rigorous model for the two-photon yield which can now be compared with the 109 Cd- 113m Cd data. The 113m Cd component also produces a significant contribution to the coincidence yield from the coincidence of a single bremsstrahlung photon and a scattered electron. It is shown that the new model, with the single bremsstrahlung electron-photon coincidence contribution, provides a good description of the data.
EXTIRPATION OF THE THYMUS IN THE GUINEA PIG.

1. Accessory lobes of thymus, derived from the third pharyngeal pouch, occurring in close association with the parathyroids from the third pouch, were found in serial section of the cervical tissues of eleven out of fourteen guinea pigs, and probably would have been found in all fourteen but for a technical error. 2. It is probable, therefore, that accessory lobes of thymus having this situation and origin are usually, if not always, present in the guinea pig. 3. Additional accessory lobes of thymus belonging to, but at some distance from the main lobe were also present in several of the animals. 4. The discovery of these accessory lobes makes it certain that the guinea pig is unsuitable material for complete thymectomy, and probably complete extirpation of the thymus in this animal is rarely, if ever accomplished. 5. The extirpation experiments of previous investigators in the guinea pig must now be regarded as partial extirpations, and their results interpreted in that light. 6. Extirpation of the thymus in the guinea pig produced no changes in the writer's experiments. 7. The study of the serial sections of the cervical tissues of the guinea pig indicates that Ruben's statements regarding the parathyroid derived from the fourth pharyngeal pouch in the guinea pig are correct,—that it is much smaller than parathyroid III, may be rudimentary, and is sometimes absent at least on one side. 8. No accessory lobe of thymus was found accompanying the parathyroid from the fourth pouch, a finding also bearing out Ruben's statement that no thymus anlarge springs from the fourth pouch in the guinea pig.
A theory of transgranular stress-corrosion cracking

A model is proposed to explain transgranular stress-corrosion cracking (T-SCC) in f.c.c. materials, wherein selective dissolution at the crack tip has the effect of lowering the KIc for cleavage. Crack propagation is shown to be anisotropic, with {110} 〈001〉 growth being discontinuous due to crack arrest by dislocation blunting. Renucleation involves active dissolution of slip planes at the crack tip which changes the stress state at critical Lomer-Cottrell locks causing them to fail by cleavage. Crack growth in directions away from {110} 〈001〉 is continuous. When the crack is propagating, its instantaneous velocity is essentially independent of growth direction. The system studied was Cu-25% Au in 0.6 M NaCl solution at potentials between 300 and 430 mV (s.c.e.), which precludes hydrogen embrittlement.
Influence of Formalization on Role Stress, Organizational Commitment, and Work Alienation of Salespersons: A Cross-National Comparative Study

Organizations rely on formalization to coordinate the efforts of employees; however, this practice has been found to have a negative influence on role stress, organizational commitment, and work alienation of salespersons. Though the negative influence of formalization in the United States has been known for some time, we still cannot predict if similar relationships would/should be observed in other countries because the rationale developed to explain these relationships in the United States did not consider the cultural factors that influence them. With such knowledge, it would become possible to anticipate the nature of the relationship in different cultural environments. Such an approach to developing cross-national models has been often suggested but seldom implemented. By emphasizing the role of culture, this study generates practical guidelines for both practitioners and theorists.
Learning to cure, but learning to care?

Utilizing interviews with students and a key administrator, analyses of academic schedules, and observations of courses, labs, and small groups, this study examines if and how elements of the explicit preclinical curriculum may have deleterious effects on medical students’ humanitarian attributes, namely empathy. Findings from this case-study of a medical school in the United States suggest that the lack of frequent formal testing in the psycho-social aspects of patient care during the preclinical years, as well as a general reduction in curriculum hours devoted to teaching the social aspects of medicine, may serve as mechanisms behind the diminution of medical students’ levels of empathy and other positive attributes as found by previous research. Following the basic tenets of the Testing Effect and the assumption that assessment drives learning, it is argued that a feasible way to maintain and potentially cultivate these traits among medical students, without saturating an overwhelmed medical curriculum, would be to install periodic, formally graded exams into preclinical curriculums that evaluate empathy and the psycho-social aspects of care.
The Effect of the Prone Position on Pulmonary Mechanics Is Frame-Dependent

By compressing the abdomen and restricting chest wall movement, the prone position compromises pulmonary compliance. For spine surgery, placing the anesthetized patient into the prone position increases the risk of improper ventilation. In this study, we tested the hypothesis that the compromise in pulmonary compliance is related to the patient's body habitus and the surgical frame used to support the patient while in the prone position. Seventy-seven adult patients were divided into three groups according to body mass index: normal (n = 36) ≤27 kg/m 2 , heavy (n = 21) 28-31 kg/m 2 , and obese (n = 20) ≥32 kg/m 2 . Patients were placed in the prone position supported by chest rolls, a Wilson frame, or the Jackson spinal surgery table (Jackson table) according to the surgeon's preferences. Peak airway pressure (at the proximal endotracheal tube), pleural pressure (esophageal balloon), and mean arterial pressure were recorded in the supine position and prone position within 15 min of the turn. Dynamic mean (± SD) pulmonary compliance (mL/cm H 2 O) decreased when turning from the supine to the prone position in all three body mass groups when using chest rolls (normal 37 ± 5 to 29 ± 6; heavy 43 ± 2 to 34 ± 4; obese 42 ± 8 to 32 ± 6) or the Wilson frame (normal 39 ± 6 to 32 ± 7; heavy 43 ± 16 to 34 ± 10; obese 36 ± 11 to 28 ± 9). The dynamic pulmonary compliance was not altered in patients positioned on the Jackson table. Regardless of body habitus, using the Jackson table for prone positioning was not associated with a significant alteration in pulmonary or hemodynamic variables. We conclude that moving patients from the supine to the prone position during anesthesia results in a decrease in pulmonary compliance that is frame-dependent but that is not affected by body habitus. Implications: We hypothesized that compromise in pulmonary compliance in the prone position is related to the patient's body mass index and the surgical frame used. In this study, we demonstrated that prone positioning during anesthesia results in a decrease in pulmonary compliance that is frame-dependent but that is not affected by body mass index.
Serotonin signalling in the gut—functions, dysfunctions and therapeutic targets

Serotonin (5-HT) has been recognized for decades as an important signalling molecule in the gut, but it is still revealing its secrets. Novel gastrointestinal functions of 5-HT continue to be discovered, as well as distant actions of gut-derived 5-HT, and we are learning how 5-HT signalling is altered in gastrointestinal disorders. Conventional functions of 5-HT involving intrinsic reflexes include stimulation of propulsive and segmentation motility patterns, epithelial secretion and vasodilation. Activation of extrinsic vagal and spinal afferent fibres results in slowed gastric emptying, pancreatic secretion, satiation, pain and discomfort, as well as nausea and vomiting. Within the gut, 5-HT also exerts nonconventional actions such as promoting inflammation and serving as a trophic factor to promote the development and maintenance of neurons and interstitial cells of Cajal. Platelet 5-HT, originating in the gut, promotes haemostasis, influences bone development and serves many other functions. 5-HT3 receptor antagonists and 5-HT4 receptor agonists have been used to treat functional disorders with diarrhoea or constipation, respectively, and the synthetic enzyme tryptophan hydroxylase has also been targeted. Emerging evidence suggests that exploiting epithelial targets with nonabsorbable serotonergic agents could provide safe and effective therapies. We provide an overview of these serotonergic actions and treatment strategies.
Visual probability-learning in the monkey

Two rhesus monkeys were trained by the correction method in a 70:30 red-blue discrimination under conditions in which they were required to earn each opportunity for choice. In subsequent phases of the experiment, the reinforcement-ratio was changed to 50:50, then to 30:70, and again to 50:50. In the 70:30 and 30:70 phases, both monkeys maximized. In the 50:50 phases they showed non-random matching, tending on each trial to avoid the side rewarded on the preceding trials. The relation of these results to those of experiments with other species is considered.
High Performance Fortran for practical scientific algorithms: An up-to-date evaluation

Abstract A suite of High Performance Fortran (HPF) coding examples of practical scientific algorithms are examined in detail, with the idea that on these simple but non-trivial examples, we can fairly well understand issues related to different data distributions, different parallel constructs, and different programming styles (static versus dynamic allocations). Coding examples include 2D stencils solution of PDEs, N-body problem, LU factorization, several vector/matrix library routines, 2D and 3D array redistribution. Performances of HPF codes are compared to hand-written Fortran codes with message passing libraries. From 1997 to 1998, HPF compilers are improved significantly such that HPF codes perform as well as Fortran+MPI codes for all the examples investigated here. However, many important peculiarities of HPF coding still exist.
Jump resonance in a third order nonlinear control system

Abstract An analysis is presented in which a graphical method is used to gain a better understanding of jump resonance. In the frequency range of interest the orthogonal components, u and v, of the steady state first harmonic approximation are plotted in a u-v plane. Constant angular frequency loci are drawn on the plane and intersected by a circle of radius F, the magnitude of the sinusoidal forcing function. These intersections determine the amplitude of the first harmonic solution. The locus of vertical tangents, normally associated with the amplitude-frequency curve, plotted on the u-v plane is used to determine the lower jump resonant frequency. The approximation reveals that jump resonance can be precluded if the forcing function does not exceed a calculable value referred to as the threshold value. The threshold value is determined from the system parameters. For a forcing function sufficiently large it is shown that real solutions in the immediate neighborhood of angles of lag of π 2 do not exist. A critical forcing function such that a maximum lag angle of π 2 is possible may be determined from system parameters.An electronic analog computer was used to verify the results of the study.
Symbolically speaking: a connectionist model of sentence production

The ability to combine words into novel sentences has been used to argue that humans have symbolic language production abilities. Critiques of connectionist models of language often center on the inability of these models to generalize symbolically (Fodor & Pylyshyn, 1988; Marcus, 1998). To address these issues, a connectionist model of sentence production was developed. The model had variables (role-concept bindings) that were inspired by spatial representations (Landau & Jackendoff, 1993). In order to take advantage of these variables, a novel dual-pathway architecture with event semantics is proposed and shown to be better at symbolic generalization than several variants. This architecture has one pathway for mapping message content to words and a separate pathway that enforces sequencing constraints. Analysis of the model's hidden units demonstrated that the model learned different types of information in each pathway, and that the model's compositional behavior arose from the combination of these two pathways. The model's ability to balance symbolic and statistical behavior in syntax acquisition and to model aphasic double dissociations provided independent support for the dual-pathway architecture.