Eryximaque et le principe des contraires

The well-known Eryximachus’ speech in Plato’s Convivium about the relationships between love and medicine has been variously interpreted by the commentators. As he presents, in regard with medicine, a whole cosmology, his ideas were compared with those of the Pythagoreans, or Alcmaeon, or Heraclitus, or naturally with Empedocles, but it is not clear whether Eryximachus admits the principle of the opposites or that of the similars. Eryximachus’ position, and perhaps Plato’s thought in this epoch depend on this question.El célebre discurso de Erixímaco en El Banquete de Platón sobre las relaciones entre el amor y la medicina ha sido interpretado de diversas formas por los comentaristas. Como presenta, con respecto a la medicina, una cosmología entera, se han comparado sus ideas con las de los pitagóricos, con las de Alcmeón o Heráclito, y naturalmente con las de Empédocles, pero no está claro si lo que admite Erixímaco es el principio de los opuestos o el de los semejantes. La postura de Erixímaco, y quizás el pensamiento de Platón en esta época depende de esta cuestión

Acute post-exercise energy and macronutrient intake in lean and obese youth: a systematic review and meta-analysis

Aim: This review aims to determine if acute exercise affects subsequent energy and macronutrients intake in obese and non-obese children and adolescents. Methods: Databases were searched between January 2015 and December 2015 for studies reporting energy and/or macronutrients intake immediately after an acute exercise and control condition, in children and adolescents. From the initial 118 references found, 14 were included for subsequent analysis after screening representing 31 acute exercise conditions that varied in intensity, duration and modality. Results: One study found increased energy intake after exercise, seven decreased and 23 revealed no change. The meta-analysis revealed a significant effect of acute exercise on intake in obese but not in lean youth by a mean difference of −0.430 (95% confidence interval=−0.703 to −0.157, P=0.002) displaying low heterogeneity (I2=0.000; Q=5.875; df=9, P=0.752). The analysis showed that intense exercise only reduces intake in obese children (no intensity effect in lean). Unchanged macronutrients intake was reported in nine studies as opposed to three which found modified lipids, protein and/or carbohydrate intake. Conclusion: Although acute exercise does not affect energy intake in lean, it appears to reduced food intake in obese youth when intense, without altering the macronutrients composition of the meal

Effects of a twelve-week exercise intervention on subsequent compensatory behaviours in adolescent girls: an exploratory study

This is an accepted manuscript of an article published by Human Kinetics Publishers Inc. in Pediatric Exercise Science on 19/07/2019, available online: https://doi.org/10.1123/pes.2019-0012 The accepted version of the publication may differ from the final published version.Purpose: Chronic exercise programmes can induce adaptive compensatory behavioural responses through increased energy intake (EI) and/or decreased free-living physical activity in adults. These responses can negate the benefits of an exercise-induced energy deficit; however, it is unclear whether young people experience similar responses. This study examined whether exercise-induced compensation occurs in adolescent girls. Methods: Twenty-three adolescent girls, heterogeneous for weight status, completed the study. Eleven, 13-year-old adolescent girls completed a twelve-week supervised exercise intervention (EX). Twelve body size matched girls comprised the non-exercise control group (CON). Body composition, EI, free-living energy expenditure (EE) and peak oxygen uptake (V ̇O_2) were measured repeatedly over the intervention. Results: Laboratory EI (EX: 9027, 9610, 9243 kJd-1 and CON: 9953, 9770, 10052 kJd-1 at 0, 12 and 18 weeks respectively) (ES = 0.26, P = 0.46) and free living EI (EX: 7288, 6412, 5273, 4916 kJd-1 and CON: 7227, 7128, 6470, 6337 kJd-1 at 0, 6, 12 and 18 weeks respectively) (ES ≤ 0.26, P = 0.90) did not change significantly over time and were similar between groups across the duration of the study. Free-living EE was higher in EX than CON (13295 vs. 12115 kJd-1, ES ≥ 0.88, P ≥ 0.16), but no significant condition by time interactions were observed (P ≥ 0.17). Conclusion: The current findings indicate that compensatory changes in EI and EE behaviours did not occur at a group level within a small cohort of adolescent girls. However, analysis at the individual level highlights large inter-individual variability in behaviours, which suggest a larger study may be prudent to extend this initial exploratory research

Effects of a 3-month vigorous physical activity intervention on eating behaviors and body composition in overweight and obese boys and girls

YesPurpose: This study analyzes the effects of a 3-month vigorous physical activity (VPA) intervention on eating behavior and body composition in overweight and obese children and adolescents. Methods: Forty-seven participants (7-16 years) took part in the study: 28 were assigned to the intervention group (IG) (10 boys and 18 girls) and 19 in a control group (CG) (8 boys and 11 girls). Body composition (dual-energy X-ray absorptiometry), anthropometrics (body mass, height, and body mass index [BMI]), and eating behavior traits (Three Factor Eating Questionnaire-R21C) were determined before and after the VPA intervention. Results: A decrease in the percentage of body fat and BMI (−2.8% and −1.8%, respectively), and an increase in lean mass variables were found in the IG (all p ≤ 0.05). In relation to the eating behavior traits, IG subjects showed a 14% reduction in the Emotional Eating score (p = 0.04), while Cognitive Restraint score did not change after the VPA intervention. The baseline factors of the questionnaire predicted changes in body mass and fat mass variables only in the CG. Conclusion: A 3-month VPA intervention influenced eating behaviors of overweight or obese young, especially the Emotional Eating factor, in the presence of favorable body composition changes.Shanghai University of Spor

Chapter 8. Lifecycle and sustainability

International audienceThe concept of sustainability was developed in order to improve the present human living standards while maintaining the availability of the natural resources for future generations. According to this definition, technological development is a way to improve the sustainability, because it enables to meet human needs by transforming natural resources into useful products. By 2050, the urban world population is expected to approximately double to an estimated 6.4 billion2 and we are aware that the Earth’s natural resources are already limited. In this context, less impacting and more efficient industrial processes’ design represents a real challenge for engineers. From now on, the impacts of new technologies have to be assessed in detail, all along their life cycle, even before their massive industrial deployment.We should be sure that the generated impacts are actually counterbalanced by the improvement of the living standards on Earth. In this chapter, we will consider new technologies related to the development and treatment of lithium batteries. In the first part, we will demonstrate how existing studiesare already taking into account environmental impacts assessment and we will particularly emphasize the main assumptions realized using life cycle assessment (LCA) approaches. In the second part, we will focus on the end-of-life (EOL) of lithium batteries to demonstrate that the entire value chain has to be considered while arbitrating on the acceptability or not of a design decision from an environmental perspective.Les batteries de type lithium connaissent et vont connaitre un essor considérable compte tenu d'une part de leurs bonnes performances et d'autre part d'une demande sans cesse croissante d'énergie notamment pour les applications transports. Cet accroissement entraîne une consommation accrue de matières premières et exige, dès aujourd'hui, de penser « cycle de vie » et « développement durable » afin de préserver et de pérenniser les ressources naturelles. Ce chapitre décrit dans un premier temps la méthodologie de l'« analyse du cycle de vie » appliquée aux batteries au lithium à partir de l'analyse de travaux publiés dans la littérature. En particulier les points clefs de ces études sont soulignés et des améliorations indispensables dans l'application de la méthode sont proposées. Dans un deuxième temps, le chapitre décrit un rapide état de l'art du recyclage et pointe la nécessité d'intégrer et de modéliser tout le cycle de vie des batteries depuis l'extraction des ressource primaires jusqu'à la fin de vie

Production d'hydrogène par photocatalyse et conversion électrochimique dans une pile à combustible.

Le contexte énergétique actuel est favorable au développement de sources renouvelables d énergie électrique. Cette étude reporte l alimentation directe d une pile à combustible à membrane échangeuse de proton par de l hydrogène issue de réactions photocatalytiques de reformage et de déshydrogénation d alcools. Le méthanol est utilisé comme molécule modèle. La vitesse de production en hydrogène a été optimisée en jouant sur des paramètres intrinsèques aux systèmes photocatalytiques, telles que la concentration en catalyseur (TiO2), la teneur en cocatalyseur (nanoparticules de platine), l influence du flux de photons, la température, la vitesse d agitation ou encore le choix du photocatalyseur. Aussi, une méthode de synthèse hydrothermale permettant l obtention d une grande variété de TiO2 monophasiques et polyphasiques, avec des compositions et des structures cristallines différentes, a été utilisée. Le dépôt du cocatalyseur (Pt) a été appliqué à partir de différentes méthodes (photodépôt, imprégnation à humidité naissante et à échange d ions). Les activités photocatalytiques des catalyseurs ont été reliées à leurs propriétés physicochimiques. Les performances de la pile à combustible sous hydrogène photocatalytique, ont été suivies. Finalement, une expérience réalisée directement sous irradiation solaire a permis de maintenir une puissance électrique, ramenée à la surface optique des photoréacteurs, de 1 mW.cm-2 sur plusieurs heures.The current energy context plays a significant role on the renewable energy sources development. This study reports the direct feeding of a proton exchange membrane fuel cell with hydrogen produced from photocatalytic reforming and dehydrogenation of alcohols. Methanol was used as model feedstock. The hydrogen production rate was optimized by varying such parameters such as, photocatalyst concentration (TiO2), cocatalyst loading (platinum nanoparticles), the photon flux, the temperature, the stirring rate and the photocatalyst kind. Thus, hydrothermal synthesis was used to obtain various kinds of TiO2 monophasic and polyphasic, with various crystalline structures and compositions. Platinum nanoparticles were deposited using various methods (photodeposition, wetness and ions exchange impregnation). Photocatalityc activities were correlated to catalyst physicochemical properties. Fuel cell performances, fed with photocatalytic hydrogen, were checked. Finally, the electric power reached 1 mW cm-2 of photoreactors optical area, for few hours, under solar irradiation.SAVOIE-SCD - Bib.électronique (730659901) / SudocGRENOBLE1/INP-Bib.électronique (384210012) / SudocGRENOBLE2/3-Bib.électronique (384219901) / SudocSudocFranceF

Contribution de l'émission acoustique pour la gestion et la sécurité des batteries Li-ion

L'objectif de cette thèse est de démontrer que l'Emission Acoustique (AE) est une technique appropriée pour devenir un outil de diagnostic de l'état de charge, de santé et de sécurité pour les batteries lithium-ion. Ces questions sont actuellement des points clés important pour l'amélioration des performances et des durées de vie de la technologie. La structure de ce document est organisée en deux principaux chapitres expérimetaux l'un consacré à deséléments lithium-ion composés de composés d'intercalation et l'autre à desalliages de lithium.Dans le premier cas, les résultats présentés concernent le suivi par AE de la formation de la SEI et de la première intercalation des ions lithium dans la structure du graphite pour des éléments LiFePO4/C. Les événements AE provenant de plusieurs sources ont été identifiés et correspondent à la formation de gaz (bulles) et à des phénomènes de craquelures (ouvertures du bord des plans de graphène quand la SEI est formée et l'écartement quand les stades d'insertion du graphite-lithium sont finis). De plus, une étude par spectroscopie d'impédance a été menée durant un vieillissement calendaire en température sur des éléments formés à différents régimes de courant. Dans le second cas, le mécanisme d'insertion/extraction du lithium dans des éléments LiAl/LiMnO2 a été étudié en associant plusieurs techniques incluant des techniques électrochimiques, AE et post-mortem pour évaluer les mécanismes de dégradation. Lors du cyclage, les événements acoustiques sont plus intenses lors du processus de décharge et ils peuvent être attribués principalement à l'alliage avec la transformation de phase de -LiAl en -LiAl accompagnée d'une expansion volumique importante. L'émission acoustique peut ainsi offrir une nouvelle approche pour gérer le fonctionnement des technologies lithium-ion basées non plus seulement sur des paramètres électrochimiques classiques mais aussi sur des paramètres acoustiques. Des nouveaux d'états de santé et de sécurité peuvent ainsi être envisagés.The aim of this thesis is to demonstrate that the Acoustic Emission (AE) is an appropriate technique for diagnostics of for state of charge, state of health and state of safety for lithium-ion batteries. The availability and optimization of the latter issues are key points for both performance and durability improvements of this technology. The frame of this document is organized in two main result chapters focused on AE study of two different Li-ion technologies. The beginning of the thesis is focused on the monitoring of the SEI formation by AE and the first lithium ion intercalation inside the graphite structure for LiFePO4/C cells. AE events coming from different sources have been analyzed and identified. It was found that they correspond to gas emission (bubbles) and cracking phenomena (opening on the edge of the graphene plane when the SEI is formed and spacing when lithium graphite insertion stages are completed). Further, a study of the calendar aging process supported by electrochemical impedance spectroscopy linked the aging rate with the mechanism of the SEI formation characterized by AE monitoring. The second part of the thesis studied of lithium ion insertion/extraction in LiAl/LiMnO2 cells combining a variety of techniques including electrochemical characterization, AE monitoring and post-mortem analysis in order to evaluate the degradation mechanisms. It was found that during the cycling, the acoustic events are much more intensive during the discharge process and they can be attributed mainly to the alloy were the phase transformation from -LiAl to -LiAl and a huge volume expansion occurs. It was found that battery operation under abusive conditions (overcharge, overdischarge) can be detected by AE providing new rates for battery safety management.SAVOIE-SCD - Bib.électronique (730659901) / SudocGRENOBLE1/INP-Bib.électronique (384210012) / SudocGRENOBLE2/3-Bib.électronique (384219901) / SudocSudocFranceF

A systematic review of the use of the Satiety Quotient

The satiating efficiency of food has been increasingly quantified using the Satiety Quotient (SQ). The SQ integrates both the energy content of food ingested during a meal and the associated change in appetite sensations. This systematic review examines the available evidence regarding its methodological use and clinical utility. A literature search was conducted in 6 databases considering studies from 1900 to April 2020 that used SQ in adults, adolescents and children. All study designs were included. From the initial 495 references found, 52 were included. Of the studies included, 33 were acute studies (29 in adults and 4 in adolescents) and 19 were longitudinal studies in adults. A high methodological heterogeneity in the application of the SQ was observed between studies. Five main utilizations of the SQ were identified: its association with i) energy intake; ii) anthropometric variables; iii) energy expenditure/physical activity; iv) sleep quality and quantity; as well as v) to classify individuals by their satiety responsiveness (i.e. low and high satiety phenotypes). Altogether, the studies suggest the SQ as an interesting clinical tool regarding the satiety responsiveness to a meal and its changes in responses to weight loss in adults. The SQ might be a reliable clinical indicator in adults when it comes to both obesity prevention and treatment. There is a need for more standardized use of the SQ in addition to further studies to investigate its validity in different contexts and populations, especially among children and adolescents

The 24-h Energy Intake of Obese Adolescents Is Spontaneously Reduced after Intensive Exercise: A Randomized Controlled Trial in Calorimetric Chambers

Background: Physical exercise can modify subsequent energy intake and appetite and may thus be of particular interest in terms of obesity treatment. However, it is still unclear whether an intensive bout of exercise can affect the energy consumption of obese children and adolescents. [br/] Objective: To compare the impact of high vs. moderate intensity exercises on subsequent 24-h energy intake, macronutrient preferences, appetite sensations, energy expenditure and balance in obese adolescent. [br/] Design: This randomized cross-over trial involves 15 obese adolescent boys who were asked to randomly complete three 24-h sessions in a metabolic chamber, each separated by at least 7 days: (1) sedentary (SED); (2) Low-Intensity Exercise (LIE) (40% maximal oxygen uptake, VO(2)max); (3) High-Intensity Exercise (HIE) (75% VO(2)max). Results: Despite unchanged appetite sensations, 24-h total energy intake following HIE was 6-11% lower compared to LIE and SED (p<0.05), whereas no differences appeared between SED and LIE. Energy intake at lunch was 9.4% and 8.4% lower after HIE compared to SED and LIE, respectively (p<0.05). At dinner time, it was 20.5% and 19.7% lower after HIE compared to SED and LIE, respectively (p<0.01). 24-h energy expenditure was not significantly altered. Thus, the 24-h energy balance was significantly reduced during HIE compared to SED and LIE (p<0.01), whereas those of SED and LIE did not differ. [br/] Conclusions: In obese adolescent boys, HIE has a beneficial impact on 24-h energy balance, mainly due to the spontaneous decrease in energy intake during lunch and dinner following the exercise bout. Prescribing high-intensity exercises to promote weight loss may therefore provide effective results without affecting appetite sensations and, as a result, food frustrations

Active video games and health indicators in children and youth: a systematic review

BACKGROUND: Active video games (AVGs) have gained interest as a way to increase physical activity in children and youth. The effect of AVGs on acute energy expenditure (EE) has previously been reported; however, the influence of AVGs on other health-related lifestyle indicators remains unclear. OBJECTIVE: This systematic review aimed to explain the relationship between AVGs and nine health and behavioural indicators in the pediatric population (aged 0–17 years). DATA SOURCES: Online databases (MEDLINE, EMBASE, psycINFO, SPORTDiscus and Cochrane Central Database) and personal libraries were searched and content experts were consulted for additional material. DATA SELECTION: Included articles were required to have a measure of AVG and at least one relevant health or behaviour indicator: EE (both habitual and acute), adherence and appeal (i.e., participation and enjoyment), opportunity cost (both time and financial considerations, and adverse events), adiposity, cardiometabolic health, energy intake, adaptation (effects of continued play), learning and rehabilitation, and video game evolution (i.e., sustainability of AVG technology). RESULTS: 51 unique studies, represented in 52 articles were included in the review. Data were available from 1992 participants, aged 3–17 years, from 8 countries, and published from 2006–2012. Overall, AVGs are associated with acute increases in EE, but effects on habitual physical activity are not clear. Further, AVGs show promise when used for learning and rehabilitation within special populations. Evidence related to other indicators was limited and inconclusive. CONCLUSIONS: Controlled studies show that AVGs acutely increase light- to moderate-intensity physical activity; however, the findings about if or how AVG lead to increases in habitual physical activity or decreases in sedentary behaviour are less clear. Although AVGs may elicit some health benefits in special populations, there is not sufficient evidence to recommend AVGs as a means of increasing daily physical activity