4,082 research outputs found
Décomposition chimique et isotopique d'un hydrogramme de crue d'un torrent méditerranéen - Réflexions méthodologiques
La décomposition chimique et isotopique d'un hydrogramme de crue d'un petit torrent méditerranéen (Cannone, Corse, France), a été tentée dans un cas simple, en confrontant les résultats des deux méthodes et en discutant leurs limites. L'outil isotopique permet de bien différencier l'eau préexistante et l'eau nouvelle. L'analyse de la variation des éléments chimiques met en évidence la participation d'eau du soi, sans qu'il soit possible de quantifier sa contribution; elle démontre que la composition de la pluie n'est pas conservative; le rôle du pluviolessivage est mis en évidence, conjointement à celui du transfert dans la zone non-saturée. Ainsi les décompositions chimiques des hydrogrammes (en particulier celles réalisées avec la conductivité) reposent le plus souvent sur des approximations théoriquement contestables et conduisent à des erreurs notables, à l'exception toutefois de celles réalisées avec la silice.Problems of environmental water quality such as transfer of pollutants and ecosystem acidification call for a new insight to the path and the contact time of water in the different subsurface reservoirs. An isotopic and chemical hydrograph separation is carried out for a flood in a small upland watershed in the Mediterranean region (Cannone, Corsica Island, France) with special attention to a comparison between the two methods and discussion of their limits. Here, old and new water are clearly distinguished by isotopic composition. The pattern of the dissolved constituents of stream water shows the contribution of ground water, often assumed to be negligible. The non-conservative behaviour of rain-water chemistry during its path to the stream channel due to enrichment by throughfall and leaching of soils, is the main obstacle to chemical separation. Chemical separation, especially through specific conductance seems generally to be hazardous, except perhaps for dissolved silica. Checking the variation of all dissolved constituents would prevent questionable approximations
CatĂ leg de les molses d'Andorra
El catà leg és una recopilació de totes les dades publicades que fan referència a les molses d'Andorra. S'han revisat tots els exemplars d'herbari assequibles corresponents a les espècies publicades. Aquest treball representa l'estat actual del coneixement de la brioflora (molses) d'Andorra.The catalogue is a compilation of all the data published relating to the species of mosses collected in Andorra. All the available specimens published have been revised. This work represents the current knowledge of the Andorran bryoflora (mosses)
Neocolonialism in education: Cooperative learning, Western pedagogy in an Asian Context
This article is concerned with the influence of western educational approaches in non-western countries and societies. This influence is frequently referred to as educational neocolonialism in the sense that western paradigms tend to shape and influence educational systems and thinking elsewhere through the process of globalisation. Given the perceived pressure to modernise and reform in order to attain high international standards, educational policy makers in non-western countries tend to look to the west. Thus they may 'borrow' policies and practices that were originally developed and operated, and which appeared to be effective, in a very different cultural context to that of their own societies. In effecting such transfer, detailed consideration of particular aspects of the culture and heritage of the originating country is often neglected. To illustrate some of the problems that result from this, the article presents a case study of the application of Cooperative Learning, an educational method developed in the west, within an Asian context. Drawing upon Trompenaars and Hampden-Turner's typology of seven cultural dimensions, our examination of western method and eastern context reveals a complex web of cultural conflicts and mismatches. The paper concludes by suggesting that non-western cultures should seek to reconstruct imported pedagogic practices in accordance with their own world views and in line with their own norms and values
Het leereffect op de peerassessor van conventioneel en gecomputeriseerd Peer Assessment in voorgezet bèta-onderwijs
Genome-wide signatures of population bottlenecks and diversifying selection in European wolves
Genomic resources developed for domesticated species provide powerful tools for studying the evolutionary history of their wild relatives. Here we use 61K single-nucleotide polymorphisms (SNPs) evenly spaced throughout the canine nuclear genome to analyse evolutionary relationships among the three largest European populations of grey wolves in comparison with other populations worldwide, and investigate genome-wide effects of demographic bottlenecks and signatures of selection. European wolves have a discontinuous range, with large and connected populations in Eastern Europe and relatively smaller, isolated populations in Italy and the Iberian Peninsula. Our results suggest a continuous decline in wolf numbers in Europe since the Late Pleistocene, and long-term isolation and bottlenecks in the Italian and Iberian populations following their divergence from the Eastern European population. The Italian and Iberian populations have low genetic variability and high linkage disequilibrium, but relatively few autozygous segments across the genome. This last characteristic clearly distinguishes them from populations that underwent recent drastic demographic declines or founder events, and implies long-term bottlenecks in these two populations. Although genetic drift due to spatial isolation and bottlenecks seems to be a major evolutionary force diversifying the European populations, we detected 35 loci that are putatively under diversifying selection. Two of these loci flank the canine platelet-derived growth factor gene, which affects bone growth and may influence differences in body size between wolf populations. This study demonstrates the power of population genomics for identifying genetic signals of demographic bottlenecks and detecting signatures of directional selection in bottlenecked populations, despite their low background variability.Heredity advance online publication, 18 December 2013; doi:10.1038/hdy.2013.122
Leren door te corrigeren:De leerwinst van de leerlingbeoordelaar bij het nakijken van het werk van medeleerlingen in voortgezet bètaonderwijs
Cooperative learning vs confucian heritage culture's collectivism. The analysis in Viet Nam
Confucian Heritage Cultures (CHC) such as Viet Nam, China, Korea, Japan, Hong Kong and Singapore are proven to share characteristics of Collectivist society. Researchers agree that this collectivist mentality supports cooperation, that CHC’s learners/workers best perform in groups. Not satisfied with the assumed credo, which most easily concur, Phuong-Mai, Terlouw & Pilot (2005) made an effort to explore the other side of the medal, questioned the fixed assumption that cooperative learning is culturally appropriate in collectivist Asian countries. The confrontation between these two sets of values/principles (Cooperative Learning & CHC) reveals a number of cultural mismatch. Following this theoretical analysis, in this paper, we examine in the empirical data how practice goes in alignment with or cast doubt on the findings of our theoretical analysis. Outcomes are based on related literatures, specifically related to Viet Nam and a questionnaire with 647 participants. This paper also gives an overview of the on-going education reform in Viet Nam and analyses at three levels: administration, curriculum and lesson how Cooperative learning is being applied as a new and modern methodology
Cosmological Implications of a Scale Invariant Standard Model
We generalize the standard model of particle physics such it displays global
scale invariance. The gravitational action is also suitably modified such that
it respects this symmetry. This model is interesting since the cosmological
constant term is absent in the action. We find that the scale symmetry is
broken by the recently introduced cosmological symmetry breaking mechanism.
This simultaneously generates all the dimensionful parameters such as the
Newton's gravitational constant, the particle masses and the vacuum or dark
energy. We find that in its simplest version the model predicts the Higgs mass
to be very small, which is ruled out experimentally. We further generalize the
model such that it displays local scale invariance. In this case the Higgs
particle disappears from the particle spectrum and instead we find a very
massive vector boson. Hence the model gives a consistent description of
particle physics phenomenology as well as fits the cosmological dark energy.Comment: 12 pages, no figure
A real-time articulatory visual feedback approach with target presentation for second language pronunciation learning
International audienceArticulatory information can support learning or remediating pronunciation of a second language (L2). This paper describes an electromagnetic articulometer-based visual-feedback approach using an articulatory target presented in real-time to facilitate L2 pronunciation learning. This approach trains learners to adjust articulatory positions to match targets for a L2 vowel estimated from productions of vowels that overlap in both L1 and L2. Training of Japanese learners for the American English vowel /ae/ that included visual training improved its pronunciation regardless of whether audio training was also included. Articulatory visual feedback is shown to be an effective method for facilitating L2 pronunciation learning
Accuracy of the diagnosis of hypertensive nephrosclerosis in African Americans: A report from the African American Study of Kidney Disease (AASK) Trial
Accuracy of the diagnosis of hypertensive nephrosclerosis in African Americans: A report from the African American Study of Kidney Disease (AASK) Trial. African Americans have excess hypertension and end-stage renal disease presumed due to hypertension compared to Caucasians. The AASK was designed to examine the impact of antihypertensive therapies and two levels of blood pressure control on the rate of decline of GFR in African Americans with presumed hypertensive renal disease. During the pilot phase of the trial, eligible participants were requested to undergo renal biopsy to assess the underlying lesions in this population. Eighty-eight hypertensive (diastolic BP > 95mm Hg) non-diabetic African American patients between the ages of 18 to 70 years, with GFR between 25 to 70 ml/min/1.73m2 and without marked proteinuria were assessed for possible renal biopsy. Forty-three patients did not undergo renal biopsy due to refusal or contraindications. Adequate renal biopsies were obtained in 39 of the remaining 46 patients. Biopsy findings were analyzed and then compared to clinical parameters. The 39 patients studied, 29 men and 10 women, were on average 53.0 ± 11.0 years old, and had a MAP of 109 ± 15mm Hg and GFR 51.7 ± 13.6ml/min/1.73m2 (not significantly different from nonbiopsied patients). Thirty-eight of these 39 biopsies showed arteriosclerosis and/or arteriolosclerosis, severity on average 1.5 ± 0.9 and 1.5 ± 0.8, respectively on a 0 to 3+ scale. Interstitial fibrosis was moderate, 1.3 ± 0.9 (0 to 3+ scale). Segmental glomerulosclerosis was present in five biopsies, and in one patient, biopsy and clinical findings were consistent with idiopathic focal segmental glomerulosclerosis. Additional lesions included mesangiopathic glomerulonephritis in one patient, basement membrane thickening suggestive of diabetic nephropathy in one, and cholesterol emboli in two cases. Arteriolar and arterial sclerosis were tightly linked, and correlated with interstitial fibrosis and the reciprocal of serum creatinine. Global glomerulosclerosis was extensive, involving on average 43 ± 26% of glomeruli. The extent of this lesion did not correlate with degree of arteriolar or arterial thickening, but did correlate with systolic blood pressure (P = 0.0174), the reciprocal of serum creatinine (P = 0.0009), serum cholesterol (P = 0.0129) and interstitial fibrosis (P < 0.0001). These data underscore that renal biopsies in non-diabetic hypertensive African-Americans with mild to moderate renal insufficiency in the absence of marked proteinuria are overwhelmingly likely to show renal vascular lesions consistent with the clinical diagnosis of hypertensive nephrosclerosis
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