bluuebunny/crossref_metadata_2025 huggingface dataset:
Adult Age Differences in Dual Information Processes: Implications for the Role of Affective and Deliberative Processes in Older Adults' Decision Making
Authors: Peters Ellen , Hess Thomas M. , Västfjäll Daniel , Auman Corinne
Published: May 2007

Age differences in affective/experiential and deliberative processes have important theoretical implications for judgment and decision theory and important pragmatic implications for older-adult decision making. Age-related declines in the efficiency of deliberative processes predict poorer-quality decisions as we age. However, age-related adaptive processes, including motivated selectivity in the use of deliberative capacity, an increased focus on emotional goals, and greater experience, predict better or worse decisions for older adults depending on the situation. The aim of the current review is to examine adult age differences in affective and deliberative information processes in order to understand their potential impact on judgments and decisions. We review evidence for the role of these dual processes in judgment and decision making and then review two representative life-span perspectives (based on aging-related changes to cognitive or motivational processes) on the interplay between these processes. We present relevant predictions for older-adult decisions and make note of contradictions and gaps that currently exist in the literature. Finally, we review the sparse evidence about age differences in decision making and how theories and findings regarding dual processes could be applied to decision theory and decision aiding. In particular, we focus on prospect theory ( Kahneman & Tversky, 1979 ) and how prospect theory and theories regarding age differences in information processing can inform one another.
Use It—and Keep It, Longer, Probably: A Reply to Salthouse (2006)
Authors: Schooler Carmi
Published: May 2007

In this article, I call into serious question Salthouse's (2006) conclusions evaluating and disparaging the validity of the “use it or lose it” hypothesis regarding mental exercise and mental aging. I do so, in some part, by using data not discussed by Salthouse. The core of my argument relies heavily on a critical assessment of the conclusions that Salthouse derived from both his theoretical reasoning and his review of the literature. The more judicious conclusion I reach is that, although the whole story regarding cognitive function and aging is not known, at some level and to some degree, “using” it often delays the eventuality of “losing” it.
Emotional Arousal and Memory Binding: An Object-Based Framework
Authors: Mather Mara
Published: May 2007

Binding various features of an event together and maintaining these connections in memory is an essential component of episodic memories. Previous theories make contradictory predictions about the effects of emotional arousal on memory binding. In this article, I review evidence for both arousal-impaired and arousal-enhanced memory binding and explain these contradictory findings using an object-based framework. According to this framework, emotionally arousing objects attract attention that enhances binding of their constituent features. In contrast, the emotional arousal associated with one object either impairs or has no effect on the associations between that object and other distinct objects or background contextual information. After initial encoding, the attention-grabbing nature of emotionally arousing objects can lead to interference in working memory, making it more difficult to maintain other bound representations. These contrasting effects of arousal on memory binding should help predict which aspects of emotional memories are likely to be accurate and which aspects are likely to be misremembered.
The ‘Malbouffe’ Saga La Saga de la ‘Malbouffe’ Die Saga von „Malbouffe”
Authors: Rérat Alain
Published: May 2007

summary

The ‘Malbouffe’ Saga

After the end of the Second World War, a marked increase in animal and plant production was observed in France, little by little considered by consumers to be obtained at the expense of product quality. The pejorative term ‘malbouffe’ soon emerged, in connection not only with the hygiene of food, but also with its organoleptic and technological characteristics. This article focuses on food safety in France, with special attention paid to the incidence of toxi‐infections and food contaminations of biological and chemical origin. The Mad Cow outbreak is reviewed, along with its consequences for human health in the form of new variant Creutzfeldt‐Jakob's disease. It is emphasized that food‐related human mortality — almost exclusively due to biological contaminations — represented only 647 cases in 1995, i.e., 0.12 per cent of the overall mortality rate. The main contaminants were Salmonella, whose number is steadily decreasing, and Campylobacter, but parasite and phycotoxic risks are increasing. Mortality due to chemical contaminants is very low i.e., 10 cases or 0.002 per cent of overall mortality These contaminants, either accidental (dioxin, hydrocarbons, radioactive isotopes) or unavoidable (residues from phytochemicals, fertilisers) may be at the source of acute or chronic intoxications with sometimes unknown consequences. Nevertheless, food safety in France does not merit the spiteful term ‘malbouffe’.
Two palatal root canals in a maxillary second molar
Authors: De Almeida‐Gomes Fábio , Maniglia‐Ferreira Cláudio , Dos Santos Roberto Alves
Published: May 2007

In this study, we report a case of two palatal root canals in a maxillary second molar that was endodontically treated. The possibility of two palatal root canals in maxillary second molars is quite small; however, it must be taken into account in clinical and radiographic evaluation during endodontic treatment. Often, their presence is noticed only after a canal treatment due to continuing post‐operative discomfort.
Flow Field Measurement in a Crossflowing Elevated Jet
Authors: Said Nejla Mahjoub , Habli Sabra , Mhiri Hatem , Bournot Hervé , Le Palec Georges
Published: May 2007

Structural features resulting from the interaction of a turbulent round jet issuing transversely into a uniform stream are described with the help of flow visualization and the PIV technique. The jet exits from a rigidly mounted pipe projecting at a distance from the floor of a tunnel. The aim of the present work is to investigate the flow structure in the near-field jet-pipe exit. Jet-to-crossflow velocity ratios from 0.375 to 3 were revealed at Reynolds numbers from 1660 to 6330. Flows in the vertical symmetry plane and horizontal plane across the jet-wake, jet-exit, and pipe-wake regions are investigated. The measured velocity fields present quantitative characteristics of the streamlines, vortices, and topological features of the flow structures. In particular, the origin and formation of the vortices in the wake are described and shown to be fundamentally different from the well-known phenomenon of vortex shedding from solid bluff bodies.
Near-Field Flow Measurements of a Cavitating Jet Emanating From a Crown-Shaped Nozzle
Authors: Poussou Stephane , Plesniak Michael W.
Published: May 2007

The effect of a crown-shaped nozzle on cavitation is studied experimentally in the near-field of a 25 mm diameter (D) water jet at ReD=2×105 using particle image velocimetry (PIV) and high speed shadowgraphy recorded with a 5000 fps digital camera. The objectives are to passively control the jet flow structure and to examine its consequences on the physical appearance of cavitating bubbles. The experiments are performed in a closed-loop facility that enables complete optical access to the near-nozzle region. The cavitating and noncavitating mean velocity fields are obtained up to three nozzle diameters downstream and compared to those of a companion round nozzle. PIV measurements are taken in two distinct azimuthal planes passing through the tip and bottom points of the crown nozzle edge. The data include shear layer momentum thickness and vorticity thickness, spanwise vorticity distribution and streamwise normal Reynolds stress. Significant deviation from an axisymmetric shear layer is observed in the noncavitating flow consistently up to one diameter downstream, after which identical asymptotic conditions are achieved in both round and crown-shaped nozzles. Maximum magnitudes of spanwise vorticity and streamwise normal Reynolds stress are the highest downstream of the nozzle tip edges under noncavitating conditions. Significant modifications in trends and magnitudes are observed for the shear layer momentum thickness under cavitating conditions up to one diameter downstream. Qualitative flow visualization reveals that bubble growth occurs at different conditions depending on azimuthal location. Bubbles, in the form of elongated filaments, are the dominant structures produced downstream of the valley edges of the nozzle with an inclination of 45 deg with respect to the direction of the flow, and are observed to persist with significant strength up to two diameters downstream. These filaments are stretched between periodic larger-scale, spanwise bubbly clusters distorted in the shape of the nozzle outlet. The tip edges produce cavitating bubbles under conditions similar to that of a classical round nozzle. In summary, it was demonstrated that passive control of turbulent structures in the jet does impact the cavitation process.
Simulation and Analysis of High-Speed Droplet Spray
Dynamics
Authors: Shi H. , Kleinstreuer C.
Published: May 2007

An experimentally validated computer simulation model has been developed for the analysis of gas-phase and droplet characteristics of isothermal sprays generated by pressure jet atomizers. Employing a coupled Euler-Lagrange approach for the gas-droplet flow, secondary droplet breakup (based on the ETAB model), was assumed to be dominant and the k-ε model was selected for simulating the gas flow. Specifically, transient spray formation in terms of turbulent gas flow as well as droplet velocities and size distributions are provided for different back pressures. Clearly, two-way coupling of the phases is important because of the impact of significant gas entrainment, droplet momentum transfer, and turbulent dispersion. Several spray phenomena are discussed in light of low back-pressure (1atm) and high back-pressure (30atm) environments. At low back-pressure, sprays have long thin geometric features and penetrate faster and deeper than at high back-pressures because of the measurable change in air density and hence drag force. Away from the nozzle exit under relatively high back pressures, there is no distinct droplet size difference between peripheral and core regions because of the high droplet Weber numbers, leading to very small droplets which move randomly. In contrast to transient spray developments, under steady-state conditions droplets are subject to smaller drag forces due to the fully-developed gas entrainment velocities which reduce gas-liquid slip. Turbulent dispersion influences droplet trajectories significantly because of the impact of random gas-phase fluctuations.
An Application of a Gradient Theory With Dissipative Boundary Conditions to Fully Developed Turbulent Flows
Authors: Silber Gerhard , Janoske Uwe , Alizadeh Mansour , Benderoth Guenther
Published: May 2007

The paper presents a complete gradient theory of grade two, including new dissipative boundary conditions based on an axiomatic conception of a nonlocal continuum theory for materials of grade n. The total stress tensor of rank two in the equation of linear momentum contains two higher stress tensors of rank two and three. In the case of isotropic materials, both the tensors of rank two and three are tensor valued functions of the second order strain rate tensor and its first gradient. So the vector valued differential equation of motion is of order four, where the necessary dissipative boundary conditions are generated by using porosity tensors. An application to hydrodynamic turbulence by a linear theory is shown, whereby fully developed steady turbulent channel flows with fixed walls and one moving wall are also examined. The velocity distribution parameters are identified by a numerical optimization algorithm, using experimental data of velocity profiles of channel flow with fixed walls from the literature. These profiles were compared with others given in the literature. With these derived parameters, the predicted velocity gradient of a channel flow agrees well with data from the literature. In addition all simulations were successfully carried out using the finite difference method.
Direct Numerical Simulation of Bubbly Flows and Application to Cavitation Mitigation
Authors: Lu Tianshi , Samulyak Roman , Glimm James
Published: May 2007

The direct numerical simulation (DNS) method has been used to the study of the linear and shock wave propagation in bubbly fluids and the estimation of the efficiency of the cavitation mitigation in the container of the Spallation Neutron Source liquid mercury target. The DNS method for bubbly flows is based on the front tracking technique developed for free surface flows. Our front tracking hydrodynamic simulation code FronTier is capable of tracking and resolving topological changes of a large number of interfaces in two- and three-dimensional spaces. Both the bubbles and the fluid are compressible. In the application to the cavitation mitigation by bubble injection in the SNS, the collapse pressure of cavitation bubbles was calculated by solving the Keller equation with the liquid pressure obtained from the DNS of the bubbly flows. Simulations of the propagation of linear and shock waves in bubbly fluids have been performed, and a good agreement with theoretical predictions and experiments has been achieved. The validated DNS method for bubbly flows has been applied to the cavitation mitigation estimation in the SNS. The pressure wave propagation in the pure and the bubbly mercury has been simulated, and the collapse pressure of cavitation bubbles has been calculated. The efficiency of the cavitation mitigation by bubble injection has been estimated. The DNS method for bubbly flows has been validated through comparison of simulations with theory and experiments. The use of layers of nondissolvable gas bubbles as a pressure mitigation technique to reduce the cavitation erosion has been confirmed.
Getting to the bottom of feeding behaviour: who’s on top?
Authors: Cameron Jameason , Doucet Éric
Published: May 2007

Traditionally there has been a tendency to focus on peripheral “bottom-up” feeding-related signals and their resulting downstream actions on hypothalamic centers when studying the feeding behaviour of animals. A problem with this hierarchal approach emerges especially with respect to acquiring a human model attempting to explain what is ultimately a distributed control of feeding and energy balance. This review focuses on illuminating the means by which we have come to understand the complexities of feeding, and takes the next step in an attempt to propose a distinctive “top-down” view of this composite behaviour. It is argued that in evolutionary terms humans demonstrate behaviours unique to all species as represented by an expanded forebrain and the resultant psychological “non-homeostatic” mediators of feeding. Emphasis is placed on a distributionist “two-tier” model, arguing that traditional short-term (cholescystokinin, ghrelin, peptide YY, glucagon-like peptide 1, etc.) and long-term (insulin and leptin) feeding signals may be actively suppressed by the nested nuclei and projections of cortical–limbic brain areas. It is the motivational state (dependent on depletion–repletion signals of hunger and satiety) that in turn has the capability to modulate how rewarding or how palatable a food item may be perceived; thus, both sides of the two-tiered model of feeding behaviour are complimentary and interdependent all at once. In the end, this paper is both commentary and critical review. This synthesis purports that as evolutionary processes spawned consciousness, the psychology of hunger and the present-day discordance of gene–environment interaction forever changed the feeding behaviour of Homo sapiens .
Rat models of caloric intake and activity: relationships to animal physiology and human health
Authors: Young Genevieve S. , Kirkland James B.
Published: May 2007

Every rodent experiment is based on important parameters concerning the levels of caloric intake and physical activity. In many cases, these decisions are not made consciously, but are based on traditional models. For experimental models directed at the study of caloric intake and activity, the selection of parameters is usually aimed at modeling human conditions, the ultimate goal of which is to gain insight into the pathophysiology of the disease process in man. In each model, it is important to understand the influence of diet, exercise, and genetic background on physiology and the development of disease states. Along the continuum of energy intake from caloric restriction to high-fat feeding, and of energy output from total inactivity to forced exercise, a number of models are used to study different disease states. In this paper, we will evaluate the influence of the quantity and composition of diet and exercise in several animal models, and will discuss how each model can be applied to various human conditions. This review will be limited to traditional models using the rat as the experimental animal, and although it is not an exhaustive list, the models presented are those most commonly represented in the literature. We will also review the mechanisms by which each affects rat physiology, and will compare these to the analogous mechanisms in the modeled human disease state. We hope that the information presented here will help researchers make choices among the available models and will encourage discussion on the interpretation and extrapolation of results obtained from traditional and novel rodent experiments on diet, exercise, and chronic disease.
Objective assessment of childhood adherence to Canadian physical activity guidelines in relation to body composition
Authors: Wittmeier Kristy Diane Marie , Mollard Rebecca Christine , Kriellaars Dean Johannes
Published: May 2007

Low levels of childhood physical activity (PA) are a contributing factor to obesity. The objective of this study was to determine the adherence of children to PA guidelines in relation to body composition. Body fat (Slaughter equation) and body mass index (BMI) were determined during the school year (n = 251, ages 8–11 y). Daily energy expenditure (EE, kcal·kg–1·d–1) and activity time (AT, min·d–1) above moderate and vigorous intensity thresholds were assessed (accelerometry). Using EE criteria, 35.9% expended < 3.0 kcal·kg–1·d–1, 27.9% expended between 3.0 and 5.9 kcal·kg–1·d–1, 13.5% expended between 6.0 and 7.9 kcal·kg–1·d–1, and 22.9% expended ≥ 8.0 kcal·kg–1·d–1. Using AT criteria, 52.2% accumulated < 30.0 min, 31.1% accumulated 30.0–59.9 min, 12.7% accumulated 60.0–89.9 min, and 4.0% accumulated ≥ 90.0 min of AT. The EE corresponding to accumulation of AT > 90 min was 14.8 kcal·kg–1·d–1. The AT corresponding to ≥ 8 kcal·kg–1·d–1was 73.0 min. Inverse relationships were observed between EE and body fat (p = 0.0004), BMI (p = 0.002), mass (p = 0.008), and fat mass index (FMI) (p = 0.001), as well as between AT and body fat (p = 0.001), BMI (p = 0.008), mass (p = 0.017), and FMI (p = 0.002). Controlling for BMI, FMI was inversely related to EE (p = 0.049) and AT (p = 0.039). Fat-free mass index and AT were positively related (p = 0.038). Physical activity had beneficial effects on body composition for children independent of BMI. The relationship between AT and daily EE guidelines was rationalized (60 min·d–1with 8 kcal·kg–1·d–1) and demonstrated association with acceptable body composition. The 60 min·d–1of moderate activity may be a more suitable initial target than 90 min·d–1, as so few children met the upper tiers of PA guidelines.
Accurate assessment of work done and power during a Wingate anaerobic test
Authors: Franklin Kathryn L. , Gordon Rae S. , Baker Julien S. , Davies Bruce
Published: May 2007

A Monark cycle ergometer is used in physiological studies to measure work done and power. In this paper, the accuracy of a Monark rope-braked cycle ergometer was examined for a Wingate anaerobic test (WAnT). The traditional method of determining brake torque fails to take into account rope-brake theory and, as the brake torque is used to determine the moment of inertia of the flywheel, a second error is introduced into the calculation to determine the work done or power. In this study, the rope tensions were measured to determine the actual brake torque. A deceleration test was carried out to determine the moment of inertia of the system. The work done by subjects of different masses was calculated for various accelerations and it was found that the traditional calculations overestimate work done and power by between 12% and 14.7%.
Socioeconomic patterns of obesity in Canada: modeling the role of health behaviour
Authors: Ward Heather , Tarasuk Valerie , Mendelson Rena
Published: May 2007

Among Canadians, previous research has associated obesity with indicators of socioeconomic position. Several health behaviours have demonstrated similar variation, suggesting that social patterning of obesity may be partially explained by behavioural differences. The objective of this study was to examine obesity in relation to income and education among Canadians, and to characterize the indirect associations potentially occurring through fruit and vegetable intake, leisure-time physical activity (LTPA), and smoking. The present secondary analysis of the 2004 Canadian Community Health Survey was restricted to adults (25–64 y) with measured height and weight data (men, n = 3767; women, n = 3823). Interrelationships among socioeconomic indicators, behaviours, and BMI groups were examined by age-adjusted path analysis. For men, obesity was positively associated with income directly and through current smoking. Obesity was also negatively associated with education, directly and through fruit and vegetable intake, and was negatively associated with income through LTPA (r2= 0.17). For women, obesity was negatively associated with education both directly and indirectly through LTPA and with fruit and vegetable intake. No direct association was observed between income and obesity for women, but an indirect negative association existed via LTPA and fruit and vegetable intake (r2= 0.15). The direct and indirect associations between obesity and socioeconomic indicators were consistently inverse among women, but this relationship was not the case in men, suggesting that clearer social patterns of adiposity exist for Canadian women. The limited amount of variance explained by these models likely reflects the complexity of obesity development.
Circulating lipids are lowered but pancreatic islet lipid metabolism and insulin secretion are unaltered in exercise-trained female rats
Authors: Lamontagne Julien , Masiello Pellegrino , Marcil Mariannick , Delghingaro-Augusto Viviane , Burelle Yan , Prentki Marc , Nolan Christopher James
Published: May 2007

Deteriorating islet β-cell function is key in the progression of an impaired glucose tolerance state to overt type 2 diabetes (T2D), a transition that can be delayed by exercise. We have previously shown that trained rats are protected from heart ischemia–reperfusion injury in correlation with an increase in cardiac tissue fatty-acid oxidation. This trained metabolic phenotype, if induced in the islet, could also prevent β-cell failure in the pathogenesis of T2D. To assess the effect of training on islet lipid metabolism and insulin secretion, female Sprague–Dawley rats were exercised on a treadmill for 90 min/d, 4 d/week, for 10 weeks. Islet fatty-acid oxidation, the expression of key lipid metabolism genes, and glucose-stimulated insulin secretion were determined in freshly isolated islets from trained and sedentary control rats after a 48 h rest period from the last exercise. Although this moderate training reduced plasma glycerol, free fatty acids, and triglyceride levels by about 40%, consistent with reduced lipolysis from adipose tissue, it did not alter islet fatty-acid oxidation, nor the islet expression of key transcription factors and enzymes of lipid metabolism. The training also had no effect on glucose-stimulated insulin secretion or its amplification by free fatty acids. In summary, chronic exercise training did not cause an intrinsic change in islet lipid metabolism. Training did, however, substantially reduce the exposure of islets to exogenous lipid, thereby providing a potential mechanism by which exercise can prevent islet β-cell failure leading to T2D.
Changes in serum cytokines after repeated bouts of downhill running
Authors: Smith Lucille L. , McKune Andrew J. , Semple Stuart J. , Sibanda Emmanuel , Steel Helen , Anderson Ronald
Published: May 2007

The purpose of this study was to examine changes in serum cytokines after repeated bouts of aerobically biased eccentric exercise. Six untrained males ran down a –13.5% treadmill grade for 60 min on two occasions (RUN1 and RUN2) at a speed equal to 75% of their VO2 peakon a level grade; runs were spaced 14 d apart. Serum was collected before, after, and every hour for 12 h, and every 24 h for 6 d. Cytokines were assessed using 17 multiplex bead technology (Bio-Rad). Creatine kinase (CK) and delayed-onset muscle soreness (DOMS) were assessed before and 24–120 h after. Results were analyzed using a repeated measures analysis of variance (p ≤ 0.05). All comparisons were between RUN1 and RUN2. CK and DOMS were significantly elevated after RUN1 compared with RUN2, indicative of a repeated bout effect. Regarding cytokines, during the initial 12 h period after RUN2, there was a 50% decrease in pro-inflammatory interleukin-6 (IL-6), a 10% decrease in pro-inflammatory macrophage chemotactic protein-1, and a 95% elevation in anti-inflammatory interleukin-10 (IL-10). Regarding 24 h periods, after RUN2 there was an 8% reduction in pro-inflammatory interleukin-8 (IL-8). However, pro-inflammatory macrophage inflammatory factor-1β (MIF-1β) was 18% higher during the 12 h after RUN2. The overall cytokine profile suggests a slight reduction in systemic inflammation after RUN2.
Determination of “Fatmax” with 1 h cycling protocols of constant load
Authors: Meyer Tim , Gäßler Nina , Kindermann Wilfried
Published: May 2007

Several earlier studies were aimed at determining an exercise intensity that elicits maximal fat oxidation (Fatmax). However, these studies employed few different intensities or used exercise periods of too short a duration. All investigators described intensity with reference to maximal ergometric values, which might lead to metabolically inhomogeneous workloads between individuals. The aim of this study was to determine Fatmaxby overcoming these methodological shortcomings of earlier investigations. Ten healthy recreational athletes (29 ± 5 y; 75 ± 6 kg; 1.81 ± 0.04 m) conducted an initial incremental cycling test to determine VO2 peak(59.2 ± 6.1 mL·min–1·kg–1) and individual anaerobic threshold (IAT; 221 ± 476 W). Within 4 weeks, 5 constant-load tests of 1 h duration were carried out at 55%, 65%, 75%, 85%, and 95% IAT. During all tests indirect calorimetry (MetaMax I, Cortex, Leipzig, Germany) served to quantify fat oxidation. Capillary blood sampling for lactate measurements was conducted every 15 min. All subjects remained in a lactate steady state during the constant load tests, which minimized influences from excess CO2. There was no difference between the 5 intensities for the percentage of energy from fat metabolism (p = 0.12). Additionally, the intensities led to similar absolute amounts of oxidized fat (p = 0.34). However, there was a significant increase in fat metabolism with increasing exercise duration (p = 0.04). It is impossible to define one theoretical optimal intensity for fat oxidation that is true in all individuals. It is thus mandatory to perform an individual assessment with indirect calorimetry. Intra-individual day-to-day variation might render the use of several tests of long duration less applicable than incremental testing with stages of sufficient duration.
Independent associations between liver fat, visceral adipose tissue, and metabolic risk factors in men
Authors: McMillan Kathleen P. , Kuk Jennifer L. , Church Timothy S. , Blair Steven N. , Ross Robert
Published: May 2007

The independent associations between liver fat, visceral adipose tissue (AT), and metabolic risk factors are unclear. Although it has been reported that visceral AT is the strongest predictor of metabolic risk, liver fat has also been reported as a strong independent associate of a deleterious metabolic profile. We examined the independent associations between liver fat, visceral AT, and metabolic risk factors in a sample of 293 men varying widely in adiposity. Liver fat and abdominal AT were measured by computed tomography (CT). Univariate analysis revealed that liver fat was associated (p < 0.05) with triglycerides (TG), systolic blood pressure (SBP), and total cholesterol (TC), but not with glucose or high-density lipoprotein cholesterol (HDLC). Liver fat remained a significant correlate (p < 0.05) of TG and TC after control for age and subcutaneous AT or cardiorespiratory fitness (CRF), but not after adjustment for visceral AT alone. Conversely, visceral AT remained significantly associated with TG, SBP, glucose, HDLC (p < 0.01), and TC (p = 0.05) independent of liver fat, subcutaneous AT, CRF, and age. Both liver fat and visceral AT were associated with metabolic risk in men. However, when controlled for each other, visceral AT was the only independent associate of metabolic risk.
Eccentric muscle contractions induce greater oxidative stress than concentric contractions in skeletal muscle
Authors: Kon Michihiro , Tanabe Kai , Lee Hoseong , Kimura Fuminori , Akimoto Takayuki , Kono Ichiro
Published: May 2007

The purpose of this study was to examine oxidative stress in skeletal muscle after eccentric and concentric muscle contractions. Eight-week-old Institute of Cancer Research (ICR) mice (n = 90) were divided into 3 groups: eccentric muscle contraction group (ECC, n = 42), concentric muscle contraction group (CON, n = 42), and control group (pre, n = 6). The tibialis anterior muscle was stimulated via the peroneal nerve to contract either eccentrically or concentrically. The tibialis anterior muscle was isolated before and 0, 6, 12, 18, 24, 72, and 168 h after muscle contraction. Immediately after muscle contractions, thiobarbituric acid reactive substances (TBARS) in skeletal muscle significantly increased (p < 0.05) in both ECC and CON conditions. However, in the ECC group alone, the TBARS level peaked at 12 and 72 h after the contractions. There was greater migration of mononuclear cells in ECC than in CON muscle. In addition, there was a correlation between TBARS in skeletal muscle and migration of mononuclear cells in ECC muscle (r = 0.773, p < 0.01), but this correlation was not apparent in CON muscle (r = 0.324, p = 0.12). The increased mononuclear cells may reflect inflammatory cells. These data suggest that eccentric muscle contraction induces greater oxidative stress in skeletal muscle, which may in turn be due to enhanced generation of reactive oxygen species (ROS) by migrating inflammatory cells.
SENSITIVITY ANALYSIS OF OBJECTIVE FUNCTION COEFFICIENTS OF THE ASSIGNMENT PROBLEM
Authors: LIN CHI-JEN , WEN UE-PYNG
Published: May 2007

Information of sensitivity analysis, in a linear programming problem, is usually more important than the optimal solution itself. However, traditional sensitivity analysis, which perturbs exactly one coefficient and then determines the range preserving the optimality of the current optimal base, is impractical for the assignment problem. An optimal basic solution of the assignment problem is inherently degenerate, so it may be that the optimal base has changed but the optimal assignment remains unchanged. Furthermore, elements of a column (or row) in a cost matrix of assignment problem are usually closely related and change simultaneously, not uniquely. This paper focuses on two kinds of sensitivity analyses for the assignment problem. One is to determine the sensitivity range, over which the current optimal assignment or all the optimal assignments remain optimal, while perturbing the elements of one column (or row) in a cost matrix of the assignment problem simultaneously but dependently. The other is to perturb elements of one column (or row) in a cost matrix of the assignment problem simultaneously but independently. Numerical illustrations are presented to demonstrate that the approaches are useful in practice.
A MULTI-SERVER QUEUEING MODEL WITH MARKOVIAN ARRIVALS AND MULTIPLE THRESHOLDS
Authors: CHAKRAVARTHY SRINIVAS R.
Published: May 2007

We consider a multi-server queueing model in which arrivals occur according to a Markovian arrival process (MAP). There is a single-server and additional (backup) servers are added or removed depending on sets of thresholds. The service times are assumed to be exponential and the servers are assumed to be homogeneous. A comparison of this model to the classical MAP/M/c queueing model through an optimization problem yields some interesting results that are useful in practical applications. For example, we notice that positively correlated arrival process appears to benefit with the threshold type queueing model. We also give the minimum delay costs and the associated maximum setup costs so that the threshold type queueing model is to be preferred over the classical MAP/M/c model.
CORRELATIONS IN STOCHASTIC PROGRAMMING: A CASE FROM STOCHASTIC SERVICE NETWORK DESIGN
Authors: LIUM ARNT-GUNNAR , CRAINIC TEODOR GABRIEL , WALLACE STEIN W.
Published: May 2007

Deterministic models, even if used repeatedly, will not capture the essence of planning in an uncertain world. Flexibility and robustness can only be properly valued in models that use stochastics explicitly, such as stochastic optimization models. However, it may also be very important to capture how the random phenomena are related to one another. In this article we show how the solution to a stochastic service network design model depends heavily on the correlation structure among the random demands. The major goal of this paper is to discuss why this happens, and to provide insights into the effects of correlations on solution structures. We illustrate by an example.
SCHEDULING PROBLEMS WITH THE EFFECTS OF DETERIORATION AND LEARNING
Authors: WANG JI-BO , CHENG T. C. EDWIN
Published: May 2007

This paper deals with the machine scheduling problems with the effects of deterioration and learning. In this model the processing times of jobs are defined as functions of their starting times and positions in a sequence. We introduce polynomial solutions for some single machine problems and flow shop problems. The performance measures include makespan, total completion time, total weighted completion time, and maximum lateness.
ONLINE ALGORITHMS FOR SCHEDULING WITH MACHINE ACTIVATION COST
Authors: HE YONG , HAN SHUGUANG , JIANG YIWEI
Published: May 2007

In this paper, we consider a variant of the classical parallel machine scheduling problem. For this problem, we are given m potential identical machines to non-preemptively process a sequence of independent jobs. Machines need to be activated before starting to process, and each machine activated incurs a fixed machine activation cost. No machines are initially activated, and when a job is revealed the algorithm has the option to activate new machines. The objective is to minimize the sum of the makespan and activation cost of machines. We first present two optimal online algorithms with competitive ratios of 3/2 and 5/3 for m = 2, 3 cases, respectively. Then we present an online algorithm with a competitive ratio of at most 2 for general m ≥ 4, while the lower bound is 1.88.
A NOTE ON SLq(2) COVARIANCE AND QUANTUM EUCLIDEAN PLANE
Authors: BENTALHA Z. , TAHIRI M.
Published: May 2007

A quantum analogue of SL(2) covariance is given. The method consists of defining a bilinear form on SL q(2) co-module, then we ask the defined form to be invariant under SL q(2) co-actions. We showed that the required invariance leads to the standard algebraic structure of SL q(2) ideal. On the other hand, the geometry of the three-dimensional quantum Euclidean space has been evoked by computing the quantum Euclidean metric, the quantum Euclidean "distance" (the central element) and the relation of orthogonality of SO q(3) quantum group.
ROTATING QUARK STAR IN CHIRAL COLOUR DIELECTRIC MODEL
Authors: BHATTACHARYYA ABHIJIT , GHOSH SANJAY K.
Published: May 2007

The properties of rotating quark star are studied using the equation of state obtained from chiral colour dielectric model. The results are compared with those obtained from MIT bag model equation of state. The frequencies in the corotating innermost circular orbits for different central densities are evaluated and compared with the observed data.
KERR–NEWMAN SOLUTION AND ENERGY IN TELEPARALLEL EQUIVALENT OF EINSTEIN THEORY
Authors: NASHED GAMAL G. L.
Published: May 2007

An exact charged axially symmetric solution of the coupled gravitational and electromagnetic fields in the teleparallel equivalent of Einstein theory is derived. It is characterized by three parameters "the gravitational mass M, the charge parameter Q and the rotation parameter a" and its associated metric gives Kerr–Newman spacetime. The parallel vector field and the electromagnetic vector potential are axially symmetric. We then calculate the total energy using the gravitational energy–momentum. The energy is found to be shared by its interior as well as exterior. Switching off the charge parameter we find that no energy is shared by the exterior of the Kerr–Newman black hole.
ALGEBRAIC APPROACH TO THE POSITION-DEPENDENT MASS SCHRÖDINGER EQUATION FOR A SINGULAR OSCILLATOR
Authors: DONG SHI-HAI , PEÑA J. J. , PACHECO-GARCÍA C. , GARCÍA-RAVELO J.
Published: May 2007

We construct a singular oscillator Hamiltonian with a position-dependent effective mass. We find that an su(1, 1) algebra is the hidden symmetry of this quantum system and the isospectral potentials V(x) depend on the different choices of the m(x). The complete solutions are also presented by using this Lie algebra.
TIME VARIATION OF THE FINE STRUCTURE CONSTANT IN THE SPACETIME OF A COSMIC DOMAIN WALL
Authors: CAMPANELLI L. , CEA P. , TEDESCO L.
Published: May 2007

The gravitational field produced by a domain wall acts as a medium with spacetime-dependent permittivity ε. Therefore, the fine structure constant α=e2/4πε will be a time-dependent function at fixed position. The most stringent constraint on the time-variation of α comes from the natural reactor Oklo and gives [Formula: see text]. This limit constrains the tension of a cosmic domain wall to be less than σ ≲ 10-2 MeV 3, and then represents the most severe limit on the energy density of a cosmic wall stretching our Universe.
A KIND OF PREDICTION FROM STRING PHENOMENOLOGY: EXTRA MATTER AT LOW ENERGY
Authors: MUÑOZ CARLOS
Published: May 2007

We review the possibility that the Supersymmetric Standard Model arises from orbifold constructions of the E8×E8 Heterotic Superstring, and the phenomenological properties that such a model should have. In particular, trying to solve the discrepancy between the unification scale predicted by the Heterotic Superstring (≈g GUT × 5.27 × 1017 GeV ) and the value deduced from LEP experiments (≈2 × 1016 GeV ), we will predict the presence at low energies of three families of Higgses and vector-like colour triplets. Our approach relies on the Fayet–Iliopoulos breaking, and this is also a crucial ingredient, together with having three Higgs families, to obtain in these models an interesting pattern of fermion masses and mixing angles at the renormalizable level. Namely, after the gauge breaking some physical particles appear combined with other states, and the Yukawa couplings are modified in a well-controlled way. On the other hand, dangerous flavour-changing neutral currents may appear when fermions of a given charge receive their mass through couplings with several Higgs doublets. We will address this potential problem, finding that viable scenarios can be obtained for a reasonable light Higgs spectrum.
NONRELATIVISTIC ELECTRON–ELECTRON INTERACTION IN A MAXWELL–CHERN–SIMONS–PROCA MODEL ENDOWED WITH A TIMELIKE LORENTZ-VIOLATING BACKGROUND
Authors: FERREIRA MANOEL M. , TAVARES MÁRCIO S.
Published: May 2007

A planar Maxwell–Chern–Simons–Proca model endowed with a Lorentz-violating background is taken as framework to investigate the electron–electron interaction. The Dirac sector is introduced exhibiting a Yukawa and a minimal coupling with the scalar and the gauge fields, respectively. The electron–electron interaction is then exactly evaluated as the Fourier transform of the Möller scattering amplitude (carried out in the nonrelativistic limit) for the case of a purely timelike background. The interaction potential exhibits a totally screened behavior far from the origin as consequence of massive character of the physical mediators. The total interaction (scalar plus gauge potential) can always be attractive, revealing that this model may lead to the formation of electron–electron bound states.
CASIMIR STRESS ON PARALLEL PLATES IN DE SITTER SPACE WITH SIGNATURE CHANGE
Authors: SETARE M. R.
Published: May 2007

The Casimir stress on two parallel plates in a de Sitter background corresponding to different metric signatures and cosmological constants is calculated for massless scalar fields satisfying Robin boundary conditions on the plates. Our calculation shows that for the parallel plates with false vacuum between and true vacuum outside, the total Casimir pressure leads to an attraction of the plates at very early universe.
GAUGE SYMMETRIES OF STRINGS IN SUPERTWISTOR SPACE
Authors: UVAROV D. V.
Published: May 2007

Recently we considered supertwistor reformulation of the D = 4, N = 1, 2 superstring action that comprises Newman–Penrose dyad components and is classically equivalent to the Green–Schwarz one. It was shown that in the covariant κ-symmetry gauge the supertwistor representation of the string action is simplified. Here, we analyze its Hamiltonian formulation, classify the constraints on the phase-space variables, and find the covariant set of generators of the gauge symmetries. Quantum symmetries of the supertwistor representation of the string action are examined by applying the worldsheet CFT technique. Considered are various generalizations of the model from the perspective of their possible relation to the known twistor superstring models.
SEMICLASSICAL (QFT) AND QUANTUM (STRING) ROTATING BLACK HOLES AND THEIR EVAPORATION: NEW RESULTS
Authors: BOUCHAREB A. , RAMÓN MEDRANO M. , SÁNCHEZ N. G.
Published: May 2007

Combination of both quantum field theory (QFT) and string theory in curved backgrounds in a consistent framework, the string analogue model, allows us to provide a full picture of the Kerr–Newman black hole and its evaporation going beyond the current picture. We compute the quantum emission cross-section of strings by a Kerr–Newman black hole (KNbh). It shows the black hole emission at the Hawking temperature T sem in the early stage of evaporation and the new string emission featuring a Hagedorn transition into a string state of temperature Ts at the last stages. New bounds on J and Q emerge in the quantum string regime (besides the known ones of the classical/semiclassical QFT regime). The last state of evaporation of a semiclassical Kerr–Newman black hole with mass M > m Pl , angular momentum J and charge Q is a string state of temperature Ts, string mass Ms, J = 0 and Q = 0, decaying as usual quantum strings do into all kinds of particles. (Naturally, in this framework, there is no loss of information, (there is no paradox at all).) We compute the string entropy Ss(m, j) from the microscopic string density of states of mass m and spin mode j, ρ(m, j). (Besides the Hagedorn transition at Ts) we find for high j (extremal string states j → m2α′c), a new phase transition at a temperature [Formula: see text], higher than Ts. By precisely identifying the semiclassical and quantum (string) gravity regimes, we find a new formula for the Kerr black hole entropy S sem (M, J), as a function of the usual Bekenstein–Hawking entropy [Formula: see text]. For M ≫ m Pl and J < GM2/c, [Formula: see text] is the leading term, but for high angular momentum, (nearly extremal case J = GM2/c), a gravitational phase transition operates and the whole entropy S sem is drastically different from the Bekenstein–Hawking entropy [Formula: see text]. This new extremal black hole transition occurs at a temperature T sem J = (J/ℏ)T sem , higher than the Hawking temperature T sem .
INFRARED ANALYSIS OF QUANTUM FIELD THEORIES
Authors: FRASCA MARCO
Published: May 2007

We show that for a λϕ4 theory having many components, the solution with all equal components in the infrared regime is stable with respect to our expansion given by a recently devised approach to analyze strongly coupled quantum field theory. The analysis is extended to a pure Yang–Mills theory showing how, in this case, the given asymptotic series exists. In this way, many components theories in the infrared regime can be mapped to a single component scalar field theory obtaining their spectrum.
THERMAL RADIATION OF VARIOUS GRAVITATIONAL BACKGROUNDS
Authors: AKHMEDOV EMIL T. , AKHMEDOVA VALERIA , SINGLETON DOUGLAS , PILLING TERRY
Published: May 2007

We present a simple and general procedure for calculating the thermal radiation coming from any stationary metric. The physical picture is that the radiation arises as the quasiclassical tunneling of particles through a gravitational barrier. We study three cases in detail: the linear accelerating observer (Unruh radiation), the nonrotating black hole (Hawking radiation), and the rotating/orbiting observer (circular Unruh radiation). For the linear accelerating observer we obtain a thermal spectrum with the usual Unruh temperature. For the nonrotating black hole we obtain a thermal spectrum, but with a temperature twice that given by the original Hawking calculations. We discuss possible reasons for the discrepancies in temperatures as given by the two different methods. For the rotating/orbiting case the quasiclassical tunneling approach indicates that there is no thermal radiation. This result for the rotating/orbiting case has experimental implications for the experimental detection of this effect via the polarization of particles in storage rings.
SIMPLIFIED MODELING OF STEADY-STATE AND TRANSIENT BRILLOUIN GAIN IN MAGNETOACTIVE NON-CENTROSYMMETRIC SEMICONDUCTORS
Authors: SINGH M. , AGHAMKAR P. , SEN P. K.
Published: May 2007

With the aid of a hydrodynamic model of semiconductor-plasmas, a detailed analytical investigation is made to study both the steady-state and the transient Brillouin gain in magnetized non-centrosymmetric III-V semiconductors arising from the nonlinear interaction of an intense pump beam with the internally-generated acoustic wave, due to piezoelectric and electrostrictive properties of the crystal. Using the fact that the origin of coherent Brillouin scattering (CBS) lies in the third-order (Brillouin) susceptibility of the medium, we obtained an expression of the gain coefficient of backward Stokes mode in steady-state and transient regimes and studied the dependence of piezoelectricity, magnetic field and pump pulse duration on its growth rate. The threshold-pump intensity and optimum pulse duration for the onset of transient CBS are estimated. The piezoelectricity and externally-applied magnetic field substantially enhances the transient CBS gain coefficient in III-V semiconductors which can be of great use in the compression of scattered pulses.