Quantization of energy and writhe in self-repelling knots

Probably the most natural energy functional to be considered for knotted strings is that given by electrostatic repulsion. In the absence of counter-charges, a charged, knotted string evolving along the energy gradient of electrostatic repulsion would progressively tighten its knotted domain into a point on a perfectly circular string. However, in the presence of charge screening self-repelling knotted strings can be stabilized. It is known that energy functionals in which repulsive forces between repelling charges grow inversely proportionally to the third or higher power of their relative distance stabilize self-repelling knots. Especially interesting is the case of the third power since the repulsive energy becomes scale invariant and does not change upon Mobius transformations (reflections in spheres) of knotted trajectories. We observe here that knots minimizing their repulsive Mobius energy show quantization of the energy and writhe (measure of chirality) within several tested families of knots.

Assessment of Physical Activity and Energy Expenditure by GPS Combined With Accelerometry in Real-Life Conditions.

Background: Physical activity (PA) and related energy expenditure (EE) is often assessed by means of a single technique. Because of inherent limitations, single techniques may not allow for an accurate assessment both PA and related EE. The aim of this study was to develop a model to accurately assess common PA types and durations and thus EE in free-living conditions, combining data from global positioning system (GPS) and 2 accelerometers. Methods: Forty-one volunteers participated in the study. First, a model was developed and adjusted to measured EE with a first group of subjects (Protocol I, n = 12) who performed 6 structured and supervised PA. Then, the model was validated over 2 experimental phases with 2 groups (n = 12 and n = 17) performing scheduled (Protocol I) and spontaneous common activities in real-life condition (Protocol II). Predicted EE was compared with actual EE as measured by portable indirect calorimetry. Results: In protocol I, performed PA types could be recognized with little error. The duration of each PA type could be predicted with an accuracy below 1 minute. Measured and predicted EE were strongly associated (r = .97, P < .001). Conclusion: Combining GPS and 2 accelerometers allows for an accurate assessment of PA and EE in free-living situations.

New stakeholders, spaces and instruments of analysis in the context of energy relationships: Case studies from Kazakhstan and Turkmenistan

The disintegration of the USSR brought the emergence of a new geo-energy space in Central Asia. This space arose in the context of a global energy transition, which began in the late 1970s. Therefore, this new space in a changing energy world requires both new conceptual frameworks of analysis and the creation of new analytical tools. Taking into account this fact, our paper attempts to apply the theoretical framework of the Global Commodity Chain (GCC) to the case of natural resources in Central Asia. The aim of the paper is to check if there could be any Central Asia’s geo-energy space, assuming that this space would exist if natural resources were managed with regional criteria. The paper is divided into four sections. First an introduction that describes the new global energy context within natural resources of Central Asia would be integrated. Secondly, the paper justifies why the GCC methodology is suitable for the study of the value chains of energy products. Thirdly, we build up three cases studies (oil and uranium from Kazakhstan and gas from Turkmenistan) which reveal a high degree of uncertainty over the direction these chains will take. Finally, we present the conclusions of this study that state that the most plausible scenario would be the integration of energy resources of these countries in GCC where the core of the decision-making process will be far away from the region of Central Asia. Key words: Energy transition, geo-energy space, Global Commodity Chains, Central Asia

Neonatal adaptation of energy and protein metabolism

During the last decade, the development of "bedside" investigative methods, including indirect calorimetry, nutritional balance and stable isotope techniques, have given a new insight into energy and protein metabolism in the neonates. Neonates and premature infants especially, create an unusual opportunity to study the metabolic adaptation to extrauterine life because their physical environment can be controlled, their energy intake and energy expenditure can be measured and the link between their protein metabolism and the energetics of their postnatal growth can be assessed with accuracy. Thus, relatively abstract physiological concepts such as the postnatal timecourse of heat production, energy cost of growth, energy cost of physical activity, thermogenic effect of feeding, efficiency of protein gain, metabolic cost of protein gain and protein turnover have been quantified. These results show that energy expenditure and heat production rates increase postnatally from average values of 40 kcal/kgxday during the first week to 60 kcal/kgxday in the third week. This increase parellels nutritional intakes as well as the rate of weight gain. The thermogenic effect of feeding and the physical activity are relatively low and account only for an average of 5% each of the total heat production. The cost of protein turnover is the highest energy demanding process. The fact that nitrogen balance becomes positive within 72 hours after birth places the newborn in a transitional situation of dissociated balance between energy and protein metabolism: dry body mass and fat decrease while there is a gain in protein and increase in supine length. This particular situation ends during the second postnatal week and soon thereafter the rate of weight gain matches the statural growth. The goals of the following review are to summarize recent data on the physiological aspects of energy and protein metabolism directly related to the extrauterine adaptation, to describe experimental approaches which recently were adapted to the newborns in order to get "bedside results" and to discuss how far these results can help everyday's neonatal practice.

Protocol for the modeling the epidemiologic transition study: a longitudinal observational study of energy balance and change in body weight, diabetes and cardiovascular disease risk.

ABSTRACT: BACKGROUND: The prevalence of obesity has increased in societies of all socio-cultural backgrounds. To date, guidelines set forward to prevent obesity have universally emphasized optimal levels of physical activity. However there are few empirical data to support the assertion that low levels of energy expenditure in activity is a causal factor in the current obesity epidemic are very limited. METHODS: The Modeling the Epidemiologic Transition Study (METS) is a cohort study designed to assess the association between physical activity levels and relative weight, weight gain and diabetes and cardiovascular disease risk in five population-based samples at different stages of economic development. Twenty-five hundred young adults, ages 25-45, were enrolled in the study; 500 from sites in Ghana, South Africa, Seychelles, Jamaica and the United States. At baseline, physical activity levels were assessed using accelerometry and a questionnaire in all participants and by doubly labeled water in a subsample of 75 per site. We assessed dietary intake using two separate 24-h recalls, body composition using bioelectrical impedance analysis, and health history, social and economic indicators by questionnaire. Blood pressure was measured and blood samples collected for measurement of lipids, glucose, insulin and adipokines. Full examination including physical activity using accelerometry, anthropometric data and fasting glucose will take place at 12 and 24 months. The distribution of the main variables and the associations between physical activity, independent of energy intake, glucose metabolism and anthropometric measures will be assessed using cross-section and longitudinal analysis within and between sites. DISCUSSION: METS will provide insight on the relative contribution of physical activity and diet to excess weight, age-related weight gain and incident glucose impairment in five populations' samples of young adults at different stages of economic development. These data should be useful for the development of empirically-based public health policy aimed at the prevention of obesity and associated chronic diseases.

The effect of counterpoise correction and relaxation energy term to the internal rotation barriers: application to the BF3 ...NH3 and C2H4 ...SO2 dimers

The relevance of the fragment relaxation energy term and the effect of the basis set superposition error on the geometry of the BF3⋯NH3 and C2H4⋯SO2 van der Waals dimers have been analyzed. Second-order Møller-Plesset perturbation theory calculations with the d95(d,p) basis set have been used to calculate the counterpoise-corrected barrier height for the internal rotations. These barriers have been obtained by relocating the stationary points on the counterpoise-corrected potential energy surface of the processes involved. The fragment relaxation energy can have a large influence on both the intermolecular parameters and barrier height. The counterpoise correction has proved to be important for these systems

Enteral versus parenteral nutrition: comparison of energy metabolism in lean and moderately obese women.

Continuous respiratory-exchange measurements were performed on ten moderately obese and ten lean young women for 1 h before, 3 h during, and 3 h after either parenteral (IV) or intragastric (IG) administration of a nutrient mixture infused at twice the postabsorptive, resting energy expenditure (REE). REE rose significantly from 0.98 +/- 0.02 to 1.13 +/- 0.03 kcal/min (IV) and from 0.99 +/- 0.02 to 1.13 +/- 0.02 kcal/min (IG) in the lean group; from 1.10 +/- 0.02 to 1.27 +/- 0.03 kcal/min (IV) and from 1.11 +/- 0.02 to 1.29 +/- 0.03 (IG) in the obese group. These increases resulted in similar nutrient-induced thermogenesis of 10.0 +/- 0.7% (IV) and 9.3 +/- 0.9% (IG) in the lean group; of 9.2 +/- 0.7% (IV) and 10.1 +/- 0.8% (IG) in the obese. Nutrient utilization was comparable in both groups and in both routes of administration, although the response time to IG feeding was delayed. These results showed no significant difference in both the thermogenic response and nutrient utilization between moderately obese and control groups using acute IV or IG feeding.

The Conservation Reserve Program in the Presence of a Working Land Alternative: Implications for Environmental Quality, Program Participation, and Income Transfer, August 2005

The United States has invested large sums of resources in multiple conservation programs for agriculture over the past century. In this paper we focus on the impacts of program interactions. Specifically, using an integrated economic and bio-physical modeling framework, we consider the impacts of the presence of working land programs on a land retirement for an important agricultural region—the Upper Mississippi River Basin (UMRB). Compared to a land retirement only program, we find that the presence of a working land program for conservation tillage results in significantly lower predicted signups for land retirement at a given rental rate. We also find that the presence of both a large working land and land retirement program can result in more environmental benefits and income transfers than a land retirement only program can achieve.

Sex differences in obesity and the regulation of energy homeostasis.

Obesity prevalence is generally higher in women than in men, and there is also a sex difference in body fat distribution. Sex differences in obesity can be explained in part by the influence of gonadal steroids on body composition and appetite; however, behavioural, socio-cultural and chromosomal factors may also play a role. This review, which evolved from the 2008 Stock Conference on sex differences in obesity, summarizes current research and recommendations related to hormonal and neuroendocrine influences on energy balance and fat distribution. A number of important gaps in the research are identified, including a need for more studies on chromosomal sex effects on energy balance, the role of socio-cultural (i.e. gender) factors in obesity and the potential deleterious effects of high-fat diets during pregnancy on the foetus. Furthermore, there is a paucity of clinical trials examining sex-specific approaches and outcomes of obesity treatment (lifestyle-based or pharmacological), and research is urgently needed to determine whether current weight loss programmes, largely developed and tested on women, are appropriate for men. Last, it is important that both animal and clinical research on obesity be designed and analysed in such a way that data can be separately examined in both men and women.

Dual-energy CT behavior of heroin, cocaine, and typical adulterants.

PURPOSE: To investigate the dual-energy CT behavior of cocaine and heroin and of typical adulterants, and to evaluate the elemental composition of pure cocaine and heroin compared with cocaine and heroin in bodypacks. METHODS: Pure heroin and pure synthetic cocaine samples, eight different adulterants, and in each case ten different bodypacks containing cocaine or heroin, were imaged at 80, 100, 120, and 140 kVp in a dual source CT system at two different degrees of compression. Two radiologists, blinded to the samples, measured the attenuation. The dual-energy index (DEI) was calculated. We performed atomic mass spectrometry for the elemental analysis of pure cocaine, pure heroin, and heroin and cocaine in bodypacks, and 140 kVp in a dual-source CT system. RESULTS: Inter- and intra-observer agreement for attenuation measurements was good (r = 0.61-0.72; p < 0.01). The cocaine bodypacks had a positive DEI of 0.029, while the pure drugs and the heroin bodypacks had a negative DEI (-0.051 to -0.027). Levamisole was the only substance which expressed a positive DEI of 0.011, while the remaining adulterants had negative DEIs ranging between -0.015 and -0.215. Atomic mass spectrometry revealed a concentration of tin in the cocaine bodypack that was 67 times higher than in the pure synthetic cocaine sample. CONCLUSIONS: The different DEIs of bodypacks containing cocaine and heroin allow them to be distinguished with dual-energy CT. Although the material properties of pure cocaine, pure heroin, or common drug extenders do not explain the differences in DEI, tin contamination during illicit natural cocaine production may be a possible explanation.

The adjustment of energy expenditure and oxidation to energy intake: the role of carbohydrate and fat balance.

Evidence is accumulating that total body mass and its relative composition influence the rate of fat utilization in man. This effect can be explained by two factors operating in concert: (i) the effect of the size of the tissue mass and (ii) the nature of the fuel mix oxidized, i.e. the proportion of energy derived from fat vs. carbohydrate. In a cross-sectional study of 307 women with increasing degrees of obesity, we observed that the respiratory quotient (RQ) in post-absorptive conditions became progressively lower with increased body fatness, indicating a shift in substrate utilization. However, the RQ is known to be also influenced by the diet commonly ingested by the subjects. A short-term mixed diet overfeeding in lean and obese women has also demonstrated the high sensitivity of RQ to changes in energy balance. Following a one-day overfeeding (2500 kcal/day in excess of the previous 24 h energy expenditure), the magnitude of increase in RQ was identical in lean and obese subjects and the net efficiency of substrate utilization and storage was not influenced by the state of obesity.

Energy and structure of dilute hard- and soft-sphere gases

The energy and structure of dilute hard- and soft-sphere Bose gases are systematically studied in the framework of several many-body approaches, such as the variational correlated theory, the Bogoliubov model, and the uniform limit approximation, valid in the weak-interaction regime. When possible, the results are compared with the exact diffusion Monte Carlo ones. Jastrow-type correlation provides a good description of the systems, both hard- and soft-spheres, if the hypernetted chain energy functional is freely minimized and the resulting Euler equation is solved. The study of the soft-sphere potentials confirms the appearance of a dependence of the energy on the shape of the potential at gas paremeter values of x~0.001. For quantities other than the energy, such as the radial distribution functions and the momentum distributions, the dependence appears at any value of x. The occurrence of a maximum in the radial distribution function, in the momentum distribution, and in the excitation spectrum is a natural effect of the correlations when x increases. The asymptotic behaviors of the functions characterizing the structure of the systems are also investigated. The uniform limit approach is very easy to implement and provides a good description of the soft-sphere gas. Its reliability improves when the interaction weakens.

Effects of restricted methionine and energy intake on egg weight and shell quality

Selostus: Metioniinin ja energian saannin rajoittamisen vaikutukset kananmunan painoon ja laatuun

Negative impact of hypocaloric feeding and energy balance on clinical outcome in ICU patients

Résumé Introduction : Les patients nécessitant une prise en charge prolongée en milieu de soins intensifs et présentant une évolution compliquée, développent une réponse métabolique intense caractérisée généralement par un hypermétabolisme et un catabolisme protéique. La sévérité de leur atteinte pathologique expose ces patients à la malnutrition, due principalement à un apport nutritionnel insuffisant, et entraînant une balance énergétique déficitaire. Dans un nombre important d'unités de soins intensifs la nutrition des patients n'apparaît pas comme un objectif prioritaire de la prise en charge. En menant une étude prospective d'observation afin d'analyser la relation entre la balance énergétique et le pronostic clinique des patients avec séjours prolongés en soins intensifs, nous souhaitions changer cette attitude et démonter l'effet délétère de la malnutrition chez ce type de patient. Méthodes : Sur une période de 2 ans, tous les patients, dont le séjour en soins intensifs fut de 5 jours ou plus, ont été enrôlés. Les besoins en énergie pour chaque patient ont été déterminés soit par calorimétrie indirecte, soit au moyen d'une formule prenant en compte le poids du patient (30 kcal/kg/jour). Les patients ayant bénéficié d'une calorimétrie indirecte ont par ailleurs vérifié la justesse de la formule appliquée. L'âge, le sexe le poids préopératoire, la taille, et le « Body mass index » index de masse corporelle reconnu en milieu clinique ont été relevés. L'énergie délivrée l'était soit sous forme nutritionnelle (administration de nutrition entérale, parentérale ou mixte) soit sous forme non-nutritionnelle (perfusions : soluté glucosé, apport lipidique non nutritionnel). Les données de nutrition (cible théorique, cible prescrite, énergie nutritionnelle, énergie non-nutritionnelle, énergie totale, balance énergétique nutritionnelle, balance énergétique totale), et d'évolution clinique (nombre des jours de ventilation mécanique, nombre d'infections, utilisation des antibiotiques, durée du séjour, complications neurologiques, respiratoires gastro-intestinales, cardiovasculaires, rénales et hépatiques, scores de gravité pour patients en soins intensifs, valeurs hématologiques, sériques, microbiologiques) ont été analysées pour chacun des 669 jours de soins intensifs vécus par un total de 48 patients. Résultats : 48 patients de 57±16 ans dont le séjour a varié entre 5 et 49 jours (motif d'admission : polytraumatisés 10; chirurgie cardiaque 13; insuffisance respiratoire 7; pathologie gastro-intestinale 3; sepsis 3; transplantation 4; autre 8) ont été retenus. Si nous n'avons pu démontrer une relation entre la balance énergétique et plus particulièrement, le déficit énergétique, et la mortalité, il existe une relation hautement significative entre le déficit énergétique et la morbidité, à savoir les complications et les infections, qui prolongent naturellement la durée du séjour. De plus, bien que l'étude ne comporte aucune intervention et que nous ne puissions avancer qu'il existe une relation de cause à effet, l'analyse par régression multiple montre que le facteur pronostic le plus fiable est justement la balance énergétique, au détriment des scores habituellement utilisés en soins intensifs. L'évolution est indépendante tant de l'âge et du sexe, que du status nutritionnel préopératoire. L'étude ne prévoyait pas de récolter des données économiques : nous ne pouvons pas, dès lors, affirmer que l'augmentation des coûts engendrée par un séjour prolongé en unité de soins intensifs est induite par un déficit énergétique, même si le bon sens nous laisse penser qu'un séjour plus court engendre un coût moindre. Cette étude attire aussi l'attention sur l'origine du déficit énergétique : il se creuse au cours de la première semaine en soins intensifs, et pourrait donc être prévenu par une intervention nutritionnelle précoce, alors que les recommandations actuelles préconisent un apport énergétique, sous forme de nutrition artificielle, qu'à partir de 48 heures de séjour aux soins intensifs. Conclusions : L'étude montre que pour les patients de soins intensifs les plus graves, la balance énergétique devrait être considérée comme un objectif important de la prise en charge, nécessitant l'application d'un protocole de nutrition précoce. Enfin comme l'évolution à l'admission des patients est souvent imprévisible, et que le déficit s'installe dès la première semaine, il est légitime de s'interroger sur la nécessité d'appliquer ce protocole à tous les patients de soins intensifs et ceci dès leur admission. Summary Background and aims: Critically ill patients with complicated evolution are frequently hypermetabolic, catabolic, and at risk of underfeeding. The study aimed at assessing the relationship between energy balance and outcome in critically ill patients. Methods: Prospective observational study conducted in consecutive patients staying 5 days in the surgical ICU of a University hospital. Demographic data, time to feeding, route, energy delivery, and outcome were recorded. Energy balance was calculated as energy delivery minus target. Data in means+ SD, linear regressions between energy balance and outcome variables. Results: Forty eight patients aged 57±16 years were investigated; complete data are available in 669 days. Mechanical ventilation lasted 11±8 days, ICU stay 15+9 was days, and 30-days mortality was 38%. Time to feeding was 3.1 ±2.2 days. Enteral nutrition was the most frequent route with 433 days. Mean daily energy delivery was 1090±930 kcal. Combining enteral and parenteral nutrition achieved highest energy delivery. Cumulated energy balance was between -12,600+ 10,520 kcal, and correlated with complications (P<0.001), already after 1 week. Conclusion: Negative energy balances were correlated with increasing number of complications, particularly infections. Energy debt appears as a promising tool for nutritional follow-up, which should be further tested. Delaying initiation of nutritional support exposes the patients to energy deficits that cannot be compensated later on.

Comparative effects of oleoyl-estrone and a specific b3-adrenergic agonist (CL316, 243) on the expression of genes involved in energy metabolism of rat white adipose tissue

Background: The combination of oleoyl-estrone (OE) and a selective b3-adrenergic agonist (B3A; CL316,243) treatment in rats results in a profound and rapid wasting of body reserves (lipid). Methods: In the present study we investigated the effect of OE (oral gavage) and/or B3A (subcutaneous constant infusion) administration for 10 days to overweight male rats, compared with controls, on three distinct white adipose tissue (WAT) sites: subcutaneous inguinal, retroperitoneal and epididymal. Tissue weight, DNA (and, from these values cellularity), cAMP content and the expression of several key energy handling metabolism and control genes were analyzed and computed in relation to the whole site mass. Results: Both OE and B3A significantly decreased WAT mass, with no loss of DNA (cell numbers). OE decreased and B3A increased cAMP. Gene expression patterns were markedly different for OE and B3A. OE tended to decrease expression of most genes studied, with no changes (versus controls) of lipolytic but decrease of lipogenic enzyme genes. The effects of B3A were widely different, with a generalized increase in the expression of most genes, including the adrenergic receptors, and, especially the uncoupling protein UCP1. Discussion: OE and B3A, elicit widely different responses in WAT gene expression, end producing similar effects, such as shrinking of WAT, loss of fat, maintenance of cell numbers. OE acted essentially on the balance of lipolysislipogenesis and the blocking of the uptake of substrates; its decrease of synthesis favouring lipolysis. B3A induced a shotgun increase in the expression of most regulatory systems in the adipocyte, an effect that in the end favoured again the loss of lipid; this barely selective increase probably produces inefficiency, which coupled with the increase in UCP1 expression may help WAT to waste energy through thermogenesis. Conclusions: There were considerable differences in the responses of the three WAT sites. OE in general lowered gene expression and stealthily induced a substrate imbalance. B3A increasing the expression of most genes enhanced energy waste through inefficiency rather than through specific pathway activation. There was not a synergistic effect between OE and B3A in WAT, but their combined action increased WAT energy waste.