L’instruction en famille en Suisse romande : portrait des familles et motivations parentales

L'instruction en famille est une option éducative peu connue, mais en développement. Cette première enquête en Suisse romande documente les raisons de ce choix, les pratiques éducatives et le profil sociodémographique chez 137 familles. Les raisons exprimées par ces parents sont multiples et variées. Leurs principaux facteurs décisionnels sont d’ordre social ou pédagogique: une critique de la motivation et de la socialisation en contexte scolaire, la recherche d’un enrichissement des relations familiales, un projet éducatif poursuivi sous la responsabilité parentale, et une critique des programmes d’études cantonaux et des méthodes pédagogiques de l’école. Les résultats révèlent également des situations de souffrance infantile en milieu scolaire.Home education is a little-known but developing educational option. This first survey in French-speaking Switzerland documents the reasons for this choice, the educational practices and the socio-demographic profile of 137 families. The reasons expressed by these parents are many and varied. Their main decision-making factors are social or pedagogical: a critique of motivation and socialization in the school context, the search for enrichment of family relationships, an educational project pursued under parental responsibility, and a critique of cantonal educational programs and of school teaching methods. The results also reveal situations of childhood suffering in schools.Familienerziehung ist eine wenig bekannte, aber sich entwickelnde Bildungsoption. Diese erste Umfrage in der französischsprachigen Schweiz dokumentiert die Gründe für diese Wahl, die Bildungspraktiken und das soziodemografische Profil von 137 Familien. Die von diesen Eltern geäußerten Gründe sind vielfältig. Ihre Hauptentscheidungsfaktoren sind soziale oder pädagogische: eine Kritik der Motivation und Sozialisation im schulischen Kontext, die Suche nach einer Bereicherung familiärer Beziehungen, ein Bildungsprojekt, das unter elterlicher Verantwortung durchgeführt wird, und eine Kritik der Bildungsprogramme. kantonale Studien und Methoden des Schulunterrichts. Die Ergebnisse zeigen auch Situationen, in denen Kinder in Schulen leiden.L'educazione familiare è un'opzione educativa poco conosciuta ma in via di sviluppo. Questo primo sondaggio nella Svizzera romanda documenta le ragioni di questa scelta, le pratiche educative e il profilo socio-demografico di 137 famiglie. Le ragioni espresse da questi genitori sono molte e varie. I loro principali fattori decisionali sono sociali o pedagogici: una critica della motivazione e della socializzazione nel contesto scolastico, la ricerca di arricchimento delle relazioni familiari, un progetto educativo perseguito sotto la responsabilità genitoriale e una critica dei programmi educativi cantonali e metodi di insegnamento scolastico. I risultati rivelano anche situazioni di sofferenza infantile nelle scuole

Remote-sensing-based analysis of landscape change in the desiccated seabed of the Aral Sea-a potential tool for assessing the hazard degree of dust and salt storms

With the recession of the Aral Sea in Central Asia, once the world's fourth largest lake, a huge new saline desert emerged which is nowadays called the Aralkum. Saline soils in the Aralkum are a major source for dust and salt storms in the region. The aim of this study was to analyze the spatio-temporal land cover change dynamics in the Aralkum and discuss potential implications for the recent and future dust and salt storm activity in the region. MODIS satellite time series were classified from 2000-2008 and change of land cover was quantified. The Aral Sea desiccation accelerated between 2004 and 2008. The area of sandy surfaces and salt soils, which bear the greatest dust and salt storm generation potential increased by more than 36 %. In parts of the Aralkum desalinization of soils was found to take place within 4-8 years. The implication of the ongoing regression of the Aral Sea is that the expansion of saline surfaces will continue. Knowing the spatio-temporal dynamics of both the location and the surface characteristics of the source areas for dust and salt storms allows drawing conclusions about the potential hazard degree of the dust load. The remote-sensing-based land cover assessment presented in this study could be coupled with existing knowledge on the location of source areas for an early estimation of trends in shifting dust composition. Opportunities, limits, and requirements of satellite-based land cover classification and change detection in the Aralkum are discussed

Effects of dietary tryptophan and phenylalanine-tyrosine depletion on phasic alertness in healthy adults - A pilot study

Background: The synthesis of the neurotransmitters serotonin (5-HT) and dopamine (DA) in the brain can be directly altered by dietary manipulation of their relevant precursor amino acids (AA). There is evidence that altered serotonergic and dopaminergic neurotransmission are both associated with impaired attentional control. Specifically, phasic alertness is one specific aspect of attention that has been linked to changes in 5-HT and DA availability in different neurocircuitries related to attentional processes. The present study investigated the impact of short-term reductions in central nervous system 5-HT and DA synthesis, which was achieved by dietary depletion of the relevant precursor AA, on phasic alertness in healthy adult volunteers; body weight–adapted dietary tryptophan and phenylalanine–tyrosine depletion (PTD) techniques were used.Methods: The study employed a double-blind between-subject design. Fifty healthy male and female subjects were allocated to three groups in a randomized and counterbalanced manner and received three different dietary challenge conditions: acute tryptophan depletion (ATD, for the depletion of 5-HT; N=16), PTD (for the depletion of DA; N=17), and a balanced AA load (BAL; N=17), which served as a control condition. Three hours after challenge intake (ATD/PTD/BAL), phasic alertness was assessed using a standardized test battery for attentional performance (TAP). Blood samples for AA level analyses were obtained at baseline and 360 min after the challenge intake.Results: Overall, there were no significant differences in phasic alertness for the different challenge conditions. Regarding PTD administration, a positive correlation between the reaction times and the DA-related depletion magnitude was detected via the lower plasma tyrosine levels and the slow reaction times of the first run of the task. In contrast, higher tryptophan concentrations were associated with slower reaction times in the fourth run of the task in the same challenge group.Conclusion: The present study is the first to demonstrate preliminary data that support an association between decreased central nervous system DA synthesis, which was achieved by dietary depletion strategies, and slower reaction times in specific runs of a task designed to assess phasic alertness in healthy adult volunteers; these findings are consistent with previous evidence that links phasic alertness with dopaminergic neurotransmission. A lack of significant differences between the three groups could be due to compensatory mechanisms and the limited sample size, as well as the dietary challenge procedures administered to healthy participants and the strict exclusion criteria used. The potential underlying neurochemical processes related to phasic alertness should be the subject of further investigations

EPR on biological samples beyond the limits of superconducting magnets \u2013The primary donor cation of purple bacterial photosynthesis

The g-matrix of a free radical is an important observable that yields information on its electronic structure. It is usually measured by electron paramagnetic resonance (EPR) under "high field" conditions, where the spectral splitting of the principal g-factor components is larger than the line width due to unresolved hyperfine splitting. For large organic molecules such as the primary electron donor in photosynthetic reaction centers (RC) this usually requires fields above ii T, or, for fields between 3 and 11 T, full deuteration and/or single-crystal work. When trying to obtain improved spectral resolution a major concern is the presence of g-strain which leads to extra line broadening. Here we show that g-strain is negligible for bacterial RCs up to a field of 24 T. We investigated the temperature dependence of the g-anisotropy for RCs from Rhodobacter (Rb.) sphaeroides using different detergents and find that within experimental errors there is no change in the principal g-matrix components up to 200 K. This is the first report of a successful EPR experiment on a biological sample above the limits of superconducting magnets