974 resultados para electronic energy loss


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We employed the Density Functional Theory along with small basis sets, B3LYP/LANL2DZ, for the study of FeTIM complexes with different pairs of axial ligands (CO, H(2)O, NH(3), imidazole and CH(3)CN). These calculations did not result in relevant changes of molecular quantities as bond lengths, vibrational frequencies and electronic populations supporting any significant back-donation to the carbonyl or acetonitrile axial ligands. Moreover, a back-donation mechanism to the macrocycle cannot be used to explain the observed changes in molecular properties along these complexes with CO or CH(3)CN. This work also indicates that complexes with CO show smaller binding energies and are less stable than complexes with CH(3)CN. Further, the electronic band with the largest intensity in the visible region (or close to this region) is associated to the transition from an occupied 3d orbital on iron to an empty pi* orbital located at the macrocycle. The energy of this Metal-to-Ligand Charge Transfer (MLCT) transition shows a linear relation to the total charge of the macrocycle in these complexes as given by Mulliken or Natural Population Analysis (NPA) formalisms. Finally, the macrocycle total charge seems to be influenced by the field induced by the axial ligands. (C) 2011 Elsevier Ltd. All rights reserved.

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Quantum mechanical calculations at the B3LYP theory level, together with the 6-31G* basis set, were employed to obtain the energy, ionization potential, and polarizabilites for dipyridamole and derivatives, which are compared with their biological activity. Density functional calculations of the spin densities were performed for radical formed by electron abstraction of dipyridamole and derivatives. The unpaired electron remains in dipyridamole is localized on the nitrogen atoms in the substituent positions 1, 3, 5, 7, 11, 12, 13, 14, with participation of the 9 and 10 carbons in the pyrimido-pyrimidine ring. The antioxidant activity is related with ionization potential, polarizability and Log P.

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Casitas b-lineage lymphoma (c-Cbl) is a multiadaptor protein with E3-ubiquitin ligase activity residing within its RING finger domain. We have previously reported that c-Cbl–deficient mice exhibit elevated energy expenditure, reduced adiposity, and improved insulin action. In this study, we examined mice expressing c-Cbl protein with a loss-of-function mutation within the RING finger domain (c-CblA/– mice). Compared with control animals, c-CblA/– mice display a phenotype that includes reduced adiposity, despite greater food intake; reduced circulating insulin, leptin, and triglyceride levels; and improved glucose tolerance. c-CblA/– mice also display elevated oxygen consumption (13%) and are protected against high-fat diet–induced obesity and insulin resistance. Unlike c-CblA/– mice, mice expressing a mutant c-Cbl with the phosphatidylinositol (PI) 3-kinase binding domain ablated (c-CblF/F mice) exhibited an insulin sensitivity, body composition, and energy expenditure similar to that of wild-type animals. These results indicate that c-Cbl ubiquitin ligase activity, but not c-Cbl–dependent activation of PI 3-kinase, plays a key role in the regulation of whole-body energy metabolism.

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In this paper we examine the problem of finding an optimal position for a receiver node in a single-hop sensor network. The basic idea is to minimize the network energy consumption according to a particular network cost function. Our contribution is to simply show the effect of signal path loss rates and sensor weighting on the optimal receiver position.

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Background:  Whether calcium supplementation can reduce osteoporotic fractures is uncertain. We did a meta-analysis to include all the randomised trials in which calcium, or calcium in combination with vitamin D, was used to prevent fracture and osteoporotic bone loss.

Methods:  We identified 29 randomised trials (n=63 897) using electronic databases, supplemented by a hand-search of reference lists, review articles, and conference abstracts. All randomised trials that recruited people aged 50 years or older were eligible. The main outcomes were fractures of all types and percentage change of bone-mineral density from baseline. Data were pooled by use of a random-effect model.

Findings:  In trials that reported fracture as an outcome (17 trials, n=52 625), treatment was associated with a 12% risk reduction in fractures of all types (risk ratio 0·88, 95% CI 0·83–0·95; p=0·0004). In trials that reported bone-mineral density as an outcome (23 trials, n=41 419), the treatment was associated with a reduced rate of bone loss of 0·54% (0·35–0·73; p<0·0001) at the hip and 1·19% (0·76–1·61%; p<0·0001) in the spine. The fracture risk reduction was significantly greater (24%) in trials in which the compliance rate was high (p<0·0001). The treatment effect was better with calcium doses of 1200 mg or more than with doses less than 1200 mg (0·80 vs 0·94; p=0·006), and with vitamin D doses of 800 IU or more than with doses less than 800 IU (0·84 vs 0·87; p=0·03).

Interpretation:  Evidence supports the use of calcium, or calcium in combination with vitamin D supplementation, in the preventive treatment of osteoporosis in people aged 50 years or older. For best therapeutic effect, we recommend minimum doses of 1200 mg of calcium, and 800 IU of vitamin D (for combined calcium plus vitamin D supplementation).

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Objective: To assess the effectiveness of a year-long workplace weight loss program in reducing risk factors of coronary heart disease.

Design: A randomised, controlled study of low fat (25% of dietary energy) diet- and/or moderate exercise-induced weight loss interventions in free-living, middle-aged men. Compliance was monitored from food and activity diaries at monthly blood pressure measurement sessions. Blood was sampled and body composition determined from dual energy X-ray absorptiometry before and after 12 months.

Subjects and setting: Fifty-eight overweight men (mean [+ or -] SD age: 43.4 [+ or -] 5.7 years; BMI 29.0 [+ or -] 2.6 kg/[m.sup.2]), recruited from a national corporation, were instructed into diet (n = 18) exercise (a 21) or control (n = 19) groups over 12 months; 16 control subjects combined diet and exercise (n = 16) for the subsequent 12 months.

Main outcome measures: At 12 months, weight, total and regional fat and lean mass, dietary energy and percentage dietary fat intake, physical activity indices, systolic and diastolic blood pressure, serum insulin, blood lipids and lipoproteins.

Statistical analyses: Differences between groups were tested using analysis of variance with Scheffe post hoc test. Differences between pre- and post-intervention variables were tested using Students' paired t-tests. Pearson's correlation coefficient and univariate linear regression identified association between dependent variables, multiple stepwise regression identified specific predictors.

Results: Weight loss with either diet or exercise resulted in a reduction in systolic blood pressure (-3.3 [+ or -] 1.7%), diastolic blood pressure (-4.8 [+ or -] 1.3%) and LDL cholesterol (-3.9 [+ or -] 2.8%), a rise in HDL cholesterol (+10.0 [+ or -] 3.8%) and a change in the LDL/HDL ratio (-8.9 [+ or -] 3.5%). Abdominal fat loss (-26.8 [+ or -] 3.6% after diet; -16.6 [+ or -] 4.5% after exercise; -21.0 [+ or -] 4.7% after diet and exercise) was the strongest predictor of change in blood pressure: twenty percent abdominal fat loss predicted a percentage fall of 2.4 [+ or -] 0.05% in systolic blood pressure and 5.4 [+ or -] 0.07% in diastolic blood pressure. Greater abdominal fat loss was associated with the greatest decrease in serum insulin (P < 0.05).

Conclusion: Modest changes in diet and exercise effected by a low cost workplace-based education program achieved weight loss, loss of abdominal fat, reduced blood pressure and serum insulin and improved blood lipid concentrations. (Nutr Diet 2002;59:87-96)


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To identify genes involved in the central regulation of energy balance, we compared hypothalamic mRNA from lean and obese Psammomys obesus, a polygenic model of obesity, using differential display PCR. One mRNA transcript was observed to be elevated in obese, and obese diabetic, P. obesus compared with lean animals and was subsequently found to be increased 4-fold in the hypothalamus of lethal yellow agouti (Ay/a) mice, a murine model of obesity and diabetes. Intracerebroventricular infusion of antisense oligonucleotide targeted to this transcript selectively suppressed its hypothalamic mRNA levels and resulted in loss of body weight in both P. obesus and Sprague Dawley rats. Reductions in body weight were mediated by profoundly reduced food intake without a concomitant reduction in metabolic rate. Yeast two-hybrid screening, and confirmation in mammalian cells by bioluminescence resonance energy transfer analysis, demonstrated that the protein it encodes interacts with endophilins, mediators of synaptic vesicle recycling and receptor endocytosis in the brain. We therefore named this transcript Src homology 3-domain growth factor receptor-bound 2-like (endophilin) interacting protein 1 (SGIP1). SGIP1 encodes a large proline-rich protein that is expressed predominantly in the brain and is highly conserved between species. Together these data suggest that SGIP1 is an important and novel member of the group of neuronal molecules required for the regulation of energy homeostasis.

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This is the third book in Garry Egger's new series of books based on his 'Professor Trim's Medically Supervised Weight Loss Program', a unique medically-based program being endorsed by GPs throughout Australia.In the same vein as Garry Egger and Rosemary Stanton's previously published fat and fibre counters, The Ultimate Energy Guide will provide a comprehensive listing of hundreds of Australian food products broken down by 'energy density', the hottest new topic in weight control research. Regulating the energy density of food that is consumed has begun to supersede previous medical arguments about fat or carbohydrate content as the pivotal factor in weight loss. This will be a quick reference listing which can be used in conjunction with the Becoming Gutless or Becoming Slim weight loss books for men and women respectively.

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The fasting metabolism of 71- to 235-d-old subantarctic fur seal (Arctocephalus tropicalis) pups from Amsterdam Island, southern Indian Ocean, was investigated during the long foraging trips of their mothers. Body lipid reserves were proportionally greater in female than male pups and higher in postmoult (37%) than premoult (10%) animals. The mass-specific rate of mass loss did not differ between the sexes but was lower than observed in other species. Daily mass loss was estimated to 56% fat, 10% protein, and 34% water. The rate of protein catabolism (15 g d−1) was negatively related to the size of initial lipid stores and accounted for 9% (±1%) of total energy expenditure. However, body composition changes during the fast were not equal between the sexes, with females relying more on protein catabolism than males (11% and 5% of total energy expenditure, respectively). Energy expenditure (270 kJ kg−1 d−1) and metabolic water production (11.5 mL kg−1 d−1) rates are the lowest reported for an otariid species. These results suggest that subantarctic fur seal pups greatly reduce activity levels to lower energy expenditure in addition to adopting protein-sparing metabolic pathways in order to survive the extreme fasts they must endure on Amsterdam Island.

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The Internet can access a large number of consumers in a more cost-effective manner than other information delivery channels. In this pilot study, we assessed whether an online weight reduction program including dietary advice plus exercise (ED) was more effective in reducing weight than an exercise-only program (EX) >12 weeks. Participants were randomized to either the ED or EX group and attended a center for anthropometric measurements and dietary assessment. Both groups wore a pedometer and set weekly goals to increase daily steps through an interactive Web site. The ED group set weekly dietary goals via the Web site and received tailored e-mail assistance. Seventy-three participants commenced and 53 (73%) completed the study [EX n = 26; ED n = 27; body mass index—mean (standard deviation): 29.7 (2.5) kg m–2, age 46.3 (10.8); 21% male]. Percent weight changes were EX, 2.1 (0.6)% and ED, 0.9 (0.6)% (P = 0.15). Both groups increased their daily steps with no difference between groups. Only the ED group significantly reduced their energy intake. Despite a greater fall in energy intake reported by the ED group and a similar increase in physical activity in both groups, setting individual dietary goals did not enhance weight loss.

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Electronic networking ('computer-mediated communication1), considered to be ‘unique domain for educational activity’ (Harasim, 1989:50) and ‘new educational paradigm’ (Mason & Kaye, 1989:23), has been widely used and researched in K-12 schooling, place-based undergraduate subjects and distance education courses. However, only a limited number of reports of usage with experienced teachers (professional development), beginning teachers (induction support) and trainee teachers (initial training) have been published. Hence, little is known about the ways in which this new medium might contribute to the acquisition and maintenance of professional knowledge in the field of teacher education. The purpose of this study was to document an application of electronic networking in an initial 'school-based1 teacher education course. Three factors which were considered to be important in the adoption of electronic networking were specifically addressed: (a) the potential of the medium to attract and maintain a representative and comprehensive audience', (b) the willingness of participants to use the medium for the notation of ideas about teaching; and, (c) the extent to which reflection on practice was evident in network messages. This study also identified and investigated other effects which emerged as participants attempted to negotiate personal relationships with new technology. A case study was selected to investigate audience, notation, reflection, and other effects, in a particular application. Data were collected using participant observation, software-generated statistics, printed documentation, university records, questionnaires, interviews and content analysis of messages. These data were used to describe and analyse network participation by trainee teachers, classroom teachers and university staff. The data revealed that an audience did exist on the electronic network but that this was not comprehensive. Teachers had difficulty accessing the network because of other school commitments, access to equipment and personal competence with microcomputers. These difficulties indicated that developing and maintaining the teacher audience may be a major problem with electronic networking in initial teacher education. This case study revealed that deeply held concerns about notation of ideas by trainee teachers and classroom teachers can be powerful reasons for limited network participation. For trainee teachers, recording ideas publicly presented special difficulties associated with written communication. They were concerned about writing for an audience; about what to write about and how to write it. The loss of visual and verbal cues which form part of face-to-face communication was also a problem leading to concerns about how messages would be received by others. However, the overwhelming concern of almost all trainee teachers about presenting their own ideas was Tear of criticism' from peers (in particular), and other participants on the network. Trainee teachers expressed concerns about the 'dangers' of putting their thoughts in writing, the scrutiny their messages might have received from others, and the public 'criticism' about what they wrote which might have appeared on the network. Knowing that messages were stored on the network, and could be retrieved at some later date, heightened anxiety about the vulnerability of written communication; what was written on one occasion may have to be defended at some later date when the views expressed initially were no longer held. Classroom teachers were also unsure about recording their own ideas in an electronic form. Like trainee teachers, they were concerned about the scrutiny their contributions might receive from other users, and the lack of visual and verbal cues which they had learnt to use in face-to-face communication. Notating ideas in text-based messages which were archived (by the software), and retrievable by others later, was also daunting to many teachers. Another major 'danger' for teachers was the possible repercussions of 'public comment' about curriculum policy and initiatives which they thought might get them into 'trouble' with their employer. Since very few messages were contributed to conferences, there was little evidence of reflection in network communication. In the main, the network was not used to share information and ideas about curriculum and teaching. Public examples of collaboration between participants were not evident, and the 'special knowledge' held by members in each distinct group of users was not elaborated and discussed. Messages were not used to request information or clarification about issues, to outline the processes by which decisions about teaching were reached, or to synthesis ideas from different sources. The potential of the medium to operationalise reflective practice was not realised. Among the effects observed, the use of an anonymous account to access the network, and the impact this had on participation (in one conference) was considered to be a particularly significant finding. While the opportunity to systematically investigate the effects of anonymity on network participation and message contributions was not realised (by the author) while the research was in progress, the effects observed and discussed are considered to be important and worthy of further investigation. In this case study, the anonymous account helped trainee teachers mask concerns about personal writing skills and fear of criticism from others, indicating that anonymity may alter communication patterns, particularly in the early stages of network use. Given the data collected in this case study, and the interpretations placed on it by the author, a pessimistic assessment of the place of electronic networking in initial teacher education courses was presented. For this situation to change - that is, for electronic discussions to become more fully integrated into course activities - four issues which need to be addressed were identified and discussed. These included clarification of the role of collaboration amongst participants in initial teacher education, the ways in which collaboration can be facilitated using electronic networking, the problems of notation - such as the difficulty of expressing ideas about teaching in written form, and the concerns about permanently archived messages - for teachers and trainee teachers, and the lack of skills which many trainee teachers bring to electronic discussions. In the context of initial teacher education, it was suggested that these four aspects require clarification and development before the potential advantages of electronic networking can be realised. Some specific suggestions about how these issues might be resolved were presented.

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Physiological response to extreme fasting in subantarctic fur seal (Arctocephalus tropicalis) pups: metabolic rates, energy reserve utilization, and water fluxes. Am J Physiol Regul Integr Comp Physiol 297: R1582–R1592, 2009. First published September 23, 2009; doi:10.1152/ajpregu.90857.2008.— Surviving prolonged fasting requires various metabolic adaptations, such as energy and protein sparing, notably when animals are simultaneously engaged in energy-demanding processes such as growth. Due to the intermittent pattern of maternal attendance, subantarctic fur seal pups have to repeatedly endure exceptionally long fasting episodes throughout the 10-mo rearing period while preparing for nutritional independence. Their metabolic responses to natural prolonged fasting (33.4 ± 3.3 days) were investigated at 7 mo of age. Within 4–6 fasting days, pups shifted into a stage of metabolic economy characterized by a minimal rate of body mass loss (0.7%/day) and decreased resting metabolic rate  (5.9 ± 0.1 ml O2 ·kg-1·day-1) that was only 10% above the level predicted for adult terrestrial mammals. Field metabolic rate (289 ± 10 kJ·kg-1 ·day-1) and water influx (7.9 ± 0.9 ml·kg-1 ·day-1) were also among the lowest reported for any young otariid, suggesting minimized energy allocation to behavioral activity and thermoregulation. Furthermore, lean tissue degradation was dramatically reduced. High initial adiposity (>48%) and predominant reliance on lipid catabolism likely contributed to the exceptional degree of protein sparing attained. Blood chemistry supported these findings and suggested utilization of alternative fuels, such as β-hydroxybutyrate and de novo synthesized glucose from fat-released glycerol. Regardless of sex and body condition, pups tended to adopt a convergent strategy of extreme energy and lean body mass conservation that appears highly adaptive for it allows some tissue growth during the repeated episodes of prolonged fasting they experience throughout their development.

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Nanosized materials are known to take on peculiar properties compared to the bulk material. Their electronic and mechanical properties are known to improve e.g. higher electrical conductivity and greater strength. Their electrochemical redox properties can change dramatically, e.g. in the case of Ag°, the E° value for Ag° → Ag+ + e can change by up to half a volt as the particle size decreases. Nanodimensional materials also have an extraordinarily high surface area to volume ratio. All of these properties would bring beneficial effects if they could be retained when the material is assembled into a structure capable of being used as an electrode – nanostructured electrodes.

Here we consider selected examples illustrating the importance of nanostructured electrodes in energy conversion (organic solar cells and fuel cells) and storage (batteries and capacitors). These examples involve the use of inorganic as well as organic conducting and semiconducting materials.

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The thesis demonstrated the architecture of adaptive intelligent systems for energy management that is capable of interacting with complex systems including the vehicle, environment, and driver components, as well as the interrelationships between these variables, to deliver fuel consumption improvements.

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Energy-autonomous buildings are possible. Completely energy self-sufficient houses can be found, for example, in Europe. If it is possible to cover the entire energy demand of a household from only renewable energy generated on site in a central European climate, what is required in a temperate climate, typical of southern Australia? This paper describes an investigation to broadly assess the technical, practical and financial feasibility of energy-autonomy for a hypothetical suburban house in Melbourne, Victoria. The findings firstly demonstrate the importance of reducing energy demand by using passive solar building strategies and energy efficient appliances to reduce demand to a reasonable level. The paper then discusses four scenarios and combinations of technologies to meet this reduced demand. The three scenarios which give energy autonomy increase the capital cost of a typical house by between 15% and 3%, and there would be insufficient roof area to accommodate the solar technologies required in two of the scenarios investigated. It is therefore concluded that while the goal of energy autonomy is technically feasible, it is not likely to be financially or practically acceptable. A fourth scenario of an energy-exporting house was also investigated and is shown to be a much more attractive option.