Efficient high-resolution video delivery over VANETs

Wireless Networks - The adoption of video-equipped vehicles in Vehicular ad-hoc networks (VANETs) is experiencing a rapid growth. It is also anticipated a substantial increase in the video content...     

Interdomain quality of service routing: setting the grounds for the way ahead

A common criticism of the current Internet is the fact that it does not offer quality of service (QoS) guarantees across autonomous system boundaries. The Border Gateway Protocol (BGP) is central to solve this problem, since it enables AS to distribute reachability information. However, BGP is agnostic of any performance or QoS metrics. For this reason, the debate about the requirements for the future interdomain routing architecture and about whether these requirements are best met by an approach of introducing changes into BGP or by replacing BGP is still open. This article provides an insight into the interdomain QoS routing problem. First, the main drawbacks of current interdomain routing with regard to the provision of QoS are identified. Second, a survey of the most relevant interdomain QoS routing approaches are described and discussed. We also give a broad perspective on challenges surrounding the issue of whether to extend or replace BGP to support QoS, with particular emphasis on the technical challenges. However, we also point out some nontechnical unsolved challenges that, in our perspective, are still almost certainly the biggest barrier to the development of interdomain QoS routing.     

Chemical safety and governance in Brazil

Chemical safety is recognized in Agenda 21(UNCED--Rio 92), as one of the most serious problems to be faced worldwide being a problem not just of governability, restricted more to the role of states and governments, but of governance at the national and international levels. It poses greater challenges for countries like Brazil where the issues of democracy, security, sustainability and equity, which are fundamental to governance, are merely incipient and still far from solved. Taking as references the analysis of four cases in the Brazilian context, we illustrate the situation from less densely populated areas (as in the cases of mercury use by gold miners in the Amazon and pesticides in agricultural producing areas), through medium-sized towns (as in the accident with cesium 137 in Goiania), to the major urban and industrial centers (as in the cases of lead from battery renovators and benzene in the oil and steel industries and oil refineries). What can be seen is a situation where problems connected with chemical safety have grown in intensity and extent far more than the capacity to deal with them. In industrializing countries, the formulation of chemical safety policies must take into account not only the complexity and uncertainties involved in understanding the problems, but also the aspects relating to the different modes and levels of vulnerability. This is necessary in order to attempt to build better contextualized and more participatory knowledge and decision-making processes at the local and global levels, which we take as basic prerequisites for governance.     

Effect of the frequency of mechanical pulses for fatigue aging testing on push-out bond strength between glass fiber posts and root dentin

The aim of this study was to evaluate the influence of the frequency of mechanical pulses during mechanical fatigue aging on bond strength between glass fiber posts and root dentin. Fiber posts were adhesively cemented in 30 bovine roots and the core was built up with composite. All specimens were subjected to mechanical cycling (45° angle; 37 °C; 50 N; 2×10⁶ pulses) at different frequencies: 2, 4, and 8 Hz. After the fatigue, each specimen was submitted to push out test. The bond strength was calculated for data analysis (one-way ANOVA, p = 0.05). The frequency did not affect the push-out (p = 0.7). The main failure mode was between dentin and cement in all groups. The mechanical pulses were not influenced by the bond strength between root dentin and fiber posts. Thus, it is possible to decrease the time-consuming in vitro tests involving posts without damaging the reliability of the test.     

Effect of Glucans from Caripia montagnei Mushroom on TNBS-Induced Colitis

In this study, we evaluated the effect of different doses of polysaccharides extracted from Caripia montagnei mushroom at different intervals of treatment on colonic injury in the model of colitis induced by 2,4,6-trinitrobenzene sulfonic acid (TNBS). The FT-IR analysis and NMR showed that the polysaccharides from this species of mushroom are composed of α- and β-glucans. The colonic damage was evaluated by macroscopic, histological, biochemical and immunologic analyses. The results showed the reduction of colonic lesions in all groups treated with the glucans. Such glucans significantly reduced the levels of IL-6 (50 and 75 mg/kg, p < 0.05), a major inflammatory cytokine. Biochemical analyses showed that the glucans from C. montagnei acted on reducing levels of alkaline phosphatase (75 mg/kg, p < 0.01) and myeloperoxidase (p < 0.001), a result confirmed by the reduction of cellular infiltration observed microscopically. The increase of catalase activity possibly indicates a protective effect of these glucans on colonic tissue, confirming their anti-inflammatory potential.     

Body composition, dietary composition, and components of metabolic syndrome in overweight and obese adults after a 12-week trial on dietary treatments focused on portion control, energy density, or glycemic index

ABSTRACT: BACKGROUND: Given the rise in obesity and associated chronic diseases, it is critical to determine optimal approaches to weight management that will also provide improvements in dietary quality and chronic disease risk factors. To our knowledge, no study has examined all these variables in subjects participating in recommended multi-disciplinary weight loss programs using different dietary strategies. Methods: This study compared effects of three dietary approaches to weight loss on body composition, dietary quality and risk factors for metabolic syndrome. In a 12-week trial, sedentary but otherwise healthy overweight and obese adults (19 M & 138 F; 38.7 +/- 6.7 y; BMI 31.8 +/- 2.2) who were attending weekly group sessions for weight loss followed either portion control, low energy density, or low glycemic index diet plans. At baseline and 12 weeks, measures included anthropometrics, body composition, 3-day food diaries, blood pressure, total lipid profile, HOMA, C-reactive protein, and fasting blood glucose and insulin. Data were analyzed by repeated measures analysis of variance. Results: All groups significantly reduced body weight and showed significant improvements in body composition (p<0.001), and components of metabolic syndrome (p<0.027 to 0.002), although HDL decreased (p<0.001). Dietary energy, %fat and %saturated fat decreased while protein intake increased significantly (p<0.001). There were no significant differences among the three groups in any variable related to body composition, dietary quality, or metabolic syndrome components. Conclusion: Different dietary approaches based on portion control, low energy density, or low glycemic index produced similar, significant improvements in body composition, dietary quality, and metabolic syndrome components in overweight and obese adults undergoing weekly weight loss meetings. This may allow for flexibility in options for dietary counseling based on patient preference.     

Nutritional status modulates rat liver cytochrome P450 arachidonic acid metabolism

Alterations in nutritional status affect hepatic cytochrome P450 levels. Since cytochromes P450 participate in the metabolism of arachidonic acid, we hypothesized that changes in liver P450 arachidonic acid metabolism occur during fasting and refeeding. Male Fisher 344 rats were either fed, fasted 48 hr (F48), fasted 48 hr and then refed 6 hr (F48/R6), or fasted 48 hr and then refed 24 hr (F48/R24). F48 rats had reduced body weight, increased plasma beta-hydroxybutyrate, and reduced plasma insulin compared with the other groups. Although there was no significant change in total liver P450 content, there was a significant 20%, 48%, and 24% reduction in total hepatic microsomal arachidonic acid metabolism in F48, F48/R6, and F48/R24 rats, respectively, compared with fed rats. Epoxygenase activity decreased by 28%, 51%, and 26% in F48, F48/R6, and F48/R24 rats, respectively. In contrast, omega-1 hydroxylase activity increased by 126% in F48 rats compared with fed rats. Immunoblotting revealed that levels of CYP2C11 protein were markedly reduced, whereas levels of CYP2E1 protein were markedly increased in the F48 and F48/R6 groups. In contrast, levels of CYP1A1, CYP1A2, CYP2B1, CYP2J3, CYP4A1, and CYP4A3 were unchanged with fasting/refeeding. Northern blots revealed that levels of CYP2C11 mRNAs were decreased, whereas CYP2E1 mRNAs were increased in F48 and F48/R6 rats. Recombinant CYP2C11 metabolized arachidonic acid primarily to epoxides with preference for the 14(S),15(R)-, 11(R), 12(S)-, and 8(S),9(R)- epoxyeicosatrienoic acid enantiomers. We conclude that (1) nutritional status affects hepatic microsomal arachidonic acid metabolism, (2) reduced epoxygenase activity in F48 and F48/R6 rats is accompanied by decreased levels of CYP2C11, (3) increased omega-1 hydroxylase activity is accompanied by augmented levels of CYP2E1, and (4) the effects of fasting on CYP2C11 and CYP2E1 expression occur at the pretranslational level.