Use of resonance Raman spectroscopy to study the phase diagram of PbZr0.52Ti0.48O3

Evidence is presented for the first time that the sharp and continuous spectral changes observed in PbZr0.52Ti0.48O3 (PZT) between 350 and 10 K with the 647.1 nm wavelength are due to a resonance Raman effect. Such a phenomenon can be explained by means of a self-trapped exciton emission oxygen deficient complex (TiTi' - VO-) of PZT powder whose energy is close to the radiation line of the laser. This kind of approach should also be very useful to distinguish the phase transition sequence for other related ferro/ piezoelectric systems

Two Cases of Cerebral Sinus Venous Thrombosis Following Chemotherapy for Non-Seminomatous Germ Cell Tumor

We report on two patients with cerebral sinus venous thrombosis following chemotherapy with cisplatin, bleomycin and etoposide for non-seminomatous germ cell tumor. Headache and neurological deficits were the leading symptoms. Cancer and cisplatin chemotherapy are well-known risk factors for thromboembolic events. The therapeutic strategy is an anticoagulant therapy. Symptoms are usually reversible within weeks under this therapy. Therefore, in patients with testicular cancer and chemotherapy who present with neurological symptoms, cerebral sinus venous thrombosis should be considered in the differential diagnosis

Dispositifs d’insertion, pratiques et transformation des représentations de l’entreprise

Ce travail constitue une approche longitudinale des représentations sociales de l’entreprise auprès d’étudiants ayant vécu des situations de transition (pratiques sociales) différentes (classique – alternance) et étant insérés depuis deux ans dans la vie professionnelle. Les auteurs s’inscrivent dans une problématique où deux champs théoriques s’éclairent mutuellement ; celui des Transitions et celui des Représentations. Les représentations sociales de l’entreprise, leur construction et leur évolution sont des moyens privilégies d’illustration des remaniements cognitifs élaborés par les sujets en situations de transition ; parallèlement les situations de transition étudiées (école-emploi) et leurs dispositifs de formation associés (classique/alternance) illustrent parfaitement la question des pratiques sociales essentielles dans l’étude des représentations. La méthode I.S.A. utilisée dans une précédente étude est reprise ici par souci de cohérence. Les résultats font apparaître des éléments importants. L’analyse longitudinale révèle des modifications des représentations sociales au cours du temps, pour les deux groupes (formation classique/formation en alternance). Même si ce ne sont là que les résultats d’une première étude longitudinale, ils apparaissent comme surprenants compte tenu des effets habituellement observés par les travaux sur les représentations et notamment sur la stabilité du « noyau ». Par ailleurs, la comparaison des représentations chez les deux groupes au bout des deux ans de vie professionnelle montre des représentations différentes et ce malgré des pratiques identiques. Parallèlement on constate que la représentation des étudiants de la formation classique, au bout des deux ans de vie professionnelle est comparable à celle des étudiants de la formation en alternance au moment où ceux-ci sortent de leur formation. Ces résultats ne peuvent pas être expliqués seulement par le dispositif de transition suivi mais aussi par l’idée selon laquelle le sujet change ses perceptions en fonction des pratiques induites par ces dispositifs (durée – statut – irréversibilité de la situation – engagement). Ainsi la perception des pratiques et son effet sur les représentations traduisent la volonté du sujet de se repositionner sur des objets sociaux forts (l’entreprise) qui participent à son projet professionnel et accompagnent son insertion sociale. Ceci donne enfin un certain crédit aux nouveaux modes de socialisation élaborés par les entreprises tout en accentuant la dynamique du sujet « sujet pro-actif » dans son appropriation du monde.This research sought to investigate Social Representations using a longitudinal approach. Pupils involved in this study took part in academic educational programs (standard versus work-based learning), and had been working for two years in a company. Both educational programs (standard versus work-based learning) give significance to Social transitions from school to work. This study uses the Social Transition and Social Representation theory. Social representations allow us to observe how people are cognitively involved in situations of transition, while Social transitions allow us to approach social conducts. The I.S.A. method, used in a previous study, was applied in this case with some interesting results. The longitudinal study showed transformations of the Social representations over time and in both groups. This was the main result obtained. These initial results are surprising, taking into consideration the usual effects observed during social representation research and in particular the fixed nature of the core element of a representation. The comparison of “standard” and “work-based learning” representations, after two years of professional experience in a company, distinguishes two different representations and this despite the same work experience. At the same time we observed that representations identified in pupils following the standard course, after 2 years of employment, were identical to those representations of apprentices on training schemes at the time they finished their training. In our opinion, these results cannot solely be explained by Social transition but also by the idea that the pupil changes his perception in relation to associated social conducts (duration – status – committment). Therefore perception of practices and the effect that this has on the representations demonstrates the will on the part of the participant to take a pro-active approach to his career project. Credit is given therefore to the different modes of socialization elaborated by companies, whilst highlighting the pupil’s willingness to be pro-active in his approach to the environment in which he finds himself

Skill transfer, expertise and talent development: An ecological dynamics perspective

In this paper, we propose an ecological dynamics perspective on expertise and talent development, with a focus on the role of skill transfer. The ecological dynamics theoretical framework provides an integrated explanation for human behaviour in sport, predicated on a conceptualisation including constraints on dynamical systems, ecological psychology and a complex systems approach in neurobiology. Three main pillars are presented, individual-environment coupling as the smallest unit of analysis; adaptation of a complex dynamical system to interacting constraints; and the regulation of action with perception) in order to discuss the functional role of behavioural variability, the usefulness of perceptual-motor exploration and the importance of general and specific skill transfer in the development of talent and expertise in athletes. In addition, practical implications for coaches and instructors are discussed, notably regarding early diversification and unstructured play and activities in talent development programs, but also through variable practice and constraints manipulation

Flexo-printed Busbarless Solar Cells for Multi-wire Interconnection

AbstractFlexographic printing is a high-throughput rotational relief printing method and represents a promising innovative approach for the front side metallization of silicon solar cells. The ability to realize narrow contact fingers with very low silver consumption makes this technology particularly interesting for busbarless solar cells with wire-interconnection like Meyer Burger's SmartWire Connection Technology (SWCT). This study intends to provide a comprehensive evaluation of the general feasibility for this approach. Fundamental printing tests are carried out to investigate important influence parameters like the flexible printing plate and the correlation between printing pressure and contact finger width. We found out that contact finger elements on elastomer printing plates down to an actual width of wf = 7 ± 2 μm can be realized using a high-resolution laser-engraving process. Furthermore, we show that printed contact finger width increases by approx. Δwf ≈ 10 μm for each Δploc = 0.05 MPa of pressure increase and thus has a strong impact on the contact grid. Busbarless Al BSF Cz-Si solar cells with flexo-printed front side metallization are fabricated and measured using Pasan GridTOUCH/SpotLIGHT-system. The best group of solar cells obtains a mean conversion efficiency of η = 19.0% and a maximum conversion efficiency of ηmax = 19.4%. A mini-module with the best two solar cells achieved a aperture conversion efficiency of η = 15.8%. Causes for cell-to-module losses are investigated and discussed in detail. In summary, we demonstrate the successful application of flexographic printing technology for the front side metallization of busbarless solar cells with multi-wire interconnection

Therapeutic paracetamol treatment in older persons induces dietary and metabolic modifications related to sulfur amino acids

Sulfur amino acids are determinant for the detoxification of paracetamol (N-acetyl-p-aminophenol) through sulfate and glutathione conjugations. Long-term paracetamol treatment is common in the elderly, despite a potential cysteine/glutathione deficiency. Detoxification could occur at the expense of anti-oxidative defenses and whole body protein stores in elderly. We tested how older persons satisfy the extra demand in sulfur amino acids induced by long-term paracetamol treatment, focusing on metabolic and nutritional aspects. Effects of 3 g/day paracetamol for 14 days on fasting blood glutathione, plasma amino acids and sulfate, urinary paracetamol metabolites, and urinary metabolomic were studied in independently living older persons (five women, five men, mean (+/- SEM) age 74 +/- 1 years). Dietary intakes were recorded before and at the end of the treatment and ingested sulfur amino acids were evaluated. Fasting blood glutathione, plasma amino acids, and sulfate were unchanged. Urinary nitrogen excretion supported a preservation of whole body proteins, but large-scale urinary metabolomic analysis revealed an oxidation of some sulfur-containing compounds. Dietary protein intake was 13% higher at the end than before paracetamol treatment. Final sulfur amino acid intake reached 37 mg/kg/day. The increase in sulfur amino acid intake corresponded to half of the sulfur excreted in urinary paracetamol conjugates. In conclusion, older persons accommodated to long-term paracetamol treatment by increasing dietary protein intake without any mobilization of body proteins, but with decreased anti-oxidative defenses. The extra demand in sulfur amino acids led to a consumption far above the corresponding population-safe recommendation

High temperature piezoelectric properties of flux-grown α-GeO 2 single crystal

International audienceThe temperature-dependence of the piezoelectric properties of trigonal -GeO2 single-crystals obtained by the high-temperature flux method was measured by the resonance technique of the electrical impedance in the 20°C-600°C range. To approach the values of the two independent piezoelectric coefficients d11 and d14, we first measured as a function of temperature the elastic coefficients S11, S14 and S66 and the dielectric permittivity 11 which are involved in the coupling coefficient k of both the thickness shear mode and the transverse mode. A Y-cut plate with a simple +45°-rotation ((YXtwl) +45°/0°/0°) was used to measure the coupling coefficient of the thickness shear mode, and two X-turned plates ((XYtwl) +45°/0°/0° and (XYtwl)-45°/0°/0°) were prepared to characterize the coupling coefficient of two transverse modes. From the whole experimental measurements, the piezoelectric coefficients of -GeO2 were calculated up to 600 °C. They show that this crystal is one of the most efficient in regard of the -quartz-like family at room temperature, and that its thermal comportment retains large piezoelectric properties up to 600°C

Hut-like pillar array Si Solar Cells

A good texturing pattern for solar cells needs to combine low Reflectance over a large wavelength range and low surface recombination to maximize the output. Nanowire and pyramid patterns offer low Reflectance in the longer and shorter wavelength regions respectively. This paper introduces an exciting new “hut” like texturing pattern with excellent performance, improving that of nanowires and pyramids; over the long and short wavelength ranges respectively. Furthermore, we analyze the effect of different structural parameters such as height, diameter, Surface Coverage (SC) and ϑ, on the solar cell performance