139 resultados para radiative transition
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The Urn Sohryngkew section of Meghalaya, NE India, located 800-1000 km from the Deccan volcanic province, is one of the most complete Cretaceous-Tertiary boundary (KTB) transitions worldwide with all defining and supporting criteria present: mass extinction of planktic foraminifera, first appearance of Danian species, delta(13)C shift, Ir anomaly (12 ppb) and KTB red layer. The geochemical signature of the KTB layer indicates not only an extraterrestrial signal (Ni and all Platinum Group Elements (PGEs)) of a second impact that postdates Chicxulub, but also a significant component resulting from condensed sedimentation (P), redox fluctuations (As, Co, Fe, Pb, Zn, and to a lesser extent Ni and Cu) and volcanism. From the late Maastrichtian C29r into the early Danian, a humid climate prevailed (kaolinite: 40-60%, detrital minerals: 50-80%). During the latest Maastrichtian, periodic acid rains (carbonate dissolution; CIA index: 70-80) associated with pulsed Deccan eruptions and strong continental weathering resulted in mesotrophic waters. The resulting super-stressed environmental conditions led to the demise of nearly all planktic foraminiferal species and blooms (>95%) of the disaster opportunist Guembelitria cretacea. These data reveal that detrimental marine conditions prevailed surrounding the Deccan volcanic province during the main phase of eruptions in C29r below the KTB. Ultimately these environmental conditions led to regionally early extinctions followed by global extinctions at the KTB. (C) 2011 Elsevier B.V. All rights reserved.
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In contrast to the majority of recently published hypotheses, we believe that the main trigger for early Toarcian anoxia is neither increased primary productivity during the Tenuicostatum and Falciferum Zones nor sudden methane hydrate degassing close to the transition between these two zones. In our opinion, this peculiar paleoceanographic episode is linked to a major, though short-lived, regression at the end of Upper Domerian. Sea-level fall resulted from sudden cooling due to increased volcanic activity. This generated global thermal insulation and subsequent glaciation. The regression is responsible for a major hiatus over NW-European epicontinental seas and is later followed by the well-known Lower Toarcian transgression. The interval corresponding to this hiatus allowed vegetation to colonise vast newly emerged surfaces. The leaching and drowning of the accumulated organo-humic matter then triggered the anoxic cycle at the transgressive maximum, concomitant with a global warming.
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This study examined the validity and reliability of a sequential "Run-Bike-Run" test (RBR) in age-group triathletes. Eight Olympic distance (OD) specialists (age 30.0 ± 2.0 years, mass 75.6 ± 1.6 kg, run VO2max 63.8 ± 1.9 ml· kg(-1)· min(-1), cycle VO2peak 56.7 ± 5.1 ml· kg(-1)· min(-1)) performed four trials over 10 days. Trial 1 (TRVO2max) was an incremental treadmill running test. Trials 2 and 3 (RBR1 and RBR2) involved: 1) a 7-min run at 15 km· h(-1) (R1) plus a 1-min transition to 2) cycling to fatigue (2 W· kg(-1) body mass then 30 W each 3 min); 3) 10-min cycling at 3 W· kg(-1) (Bsubmax); another 1-min transition and 4) a second 7-min run at 15 km· h(-1) (R2). Trial 4 (TT) was a 30-min cycle - 20-min run time trial. No significant differences in absolute oxygen uptake (VO2), heart rate (HR), or blood lactate concentration ([BLA]) were evidenced between RBR1 and RBR2. For all measured physiological variables, the limits of agreement were similar, and the mean differences were physiologically unimportant, between trials. Low levels of test-retest error (i.e. ICC <0.8, CV<10%) were observed for most (logged) measurements. However [BLA] post R1 (ICC 0.87, CV 25.1%), [BLA] post Bsubmax (ICC 0.99, CV 16.31) and [BLA] post R2 (ICC 0.51, CV 22.9%) were least reliable. These error ranges may help coaches detect real changes in training status over time. Moreover, RBR test variables can be used to predict discipline specific and overall TT performance. Cycle VO2peak, cycle peak power output, and the change between R1 and R2 (deltaR1R2) in [BLA] were most highly related to overall TT distance (r = 0.89, p < 0. 01; r = 0.94, p < 0.02; r = 0.86, p < 0.05, respectively). The percentage of TR VO2max at 15 km· h(-1), and deltaR1R2 HR, were also related to run TT distance (r = -0.83 and 0.86, both p < 0.05).
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BACKGROUND: Alterations in glucose metabolism and epithelial-mesenchymal transition (EMT) constitute two important characteristics of carcinoma progression toward invasive cancer. Despite an extensive characterization of each of them separately, the links between EMT and glucose metabolism of tumor cells remain elusive. Here we show that the neuronal glucose transporter GLUT3 contributes to glucose uptake and proliferation of lung tumor cells that have undergone an EMT. RESULTS: Using a panel of human non-small cell lung cancer (NSCLC) cell lines, we demonstrate that GLUT3 is strongly expressed in mesenchymal, but not epithelial cells, a finding corroborated in hepatoma cells. Furthermore, we identify that ZEB1 binds to the GLUT3 gene to activate transcription. Importantly, inhibiting GLUT3 expression reduces glucose import and the proliferation of mesenchymal lung tumor cells, whereas ectopic expression in epithelial cells sustains proliferation in low glucose. Using a large microarray data collection of human NSCLCs, we determine that GLUT3 expression correlates with EMT markers and is prognostic of poor overall survival. CONCLUSIONS: Altogether, our results reveal that GLUT3 is a transcriptional target of ZEB1 and that this glucose transporter plays an important role in lung cancer, when tumor cells loose their epithelial characteristics to become more invasive. Moreover, these findings emphasize the development of GLUT3 inhibitory drugs as a targeted therapy for the treatment of patients with poorly differentiated tumors.
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Bien que la transition des soins pédiatriques aux soins adultes soit extrêmement importante pour les adolescents souffrant de maladies chroniques, celle-ci se limite le plus souvent à un simple transfert. L'objectif de cet article est de décrire les barrières au bon déroulement de la transition du point de vue du patient et de sa famille, des professionnels de la santé et du système de soins; de détailler les éléments clés pour que la transition soit la moins traumatique possible; et d'énoncer les différentes approches proposées dans la littérature. [Abstract] The transition from pediatric to adult care of chronically ill adolescents Even though the transition from pediatric to adult health care is extremely important for chronically ill adolescents, most of the times it is limited to a simple transfer The objective of this paper is to describe the barriers to a smooth transition from the point of view of the patient and his/her family, the health professionals and the health system, to review the key elements for a smooth transition, and to address the different approaches proposed in the literature.
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BACKGROUND: Obesity is a contemporary epidemic that does not affect all age groups and sections of society equally. OBJECTIVE: The objective was to examine socioeconomic differences in trajectories of body mass index (BMI; in kg/m(2)) and obesity between the ages of 45 and 65 y. DESIGN: A total of 13,297 men and 4532 women from the French GAZEL (Gaz de France Electricité de France) cohort study reported their height in 1990 and their weight annually over the subsequent 18 y. Changes in BMI and obesity between ages 45 and 49 y, 50 and 54 y, 55 and 59 y, and 60 and 65 y as a function of education and occupational position (at age 35 y) were modeled by using linear mixed models and generalized estimating equations. RESULTS: BMI and obesity rates increased between the ages of 45 and 65 y. In men, BMI was higher in unskilled workers than in managers at age 45 y; this difference in BMI increased from 0.82 (95% CI: 0.66, 0.99) at 45 y to 1.06 (95% CI: 0.85, 1.27) at 65 y. Men with a primary school education compared with those with a high school degree at age 45 y had a 0.75 (95% CI: 0.51, 1.00) higher BMI, and this difference increased to 1.32 (95% CI: 1.03,1.62) at age 65 y. Obesity rates were 3.35% and 7.68% at age 45 y and 9.52% and 18.10% at age 65 y in managers and unskilled workers, respectively; the difference in obesity increased by 4.25% (95% CI: 1.87, 6.52). A similar trend was observed in women. Conclusions: Weight continues to increase in the transition between midlife and old age; this increase is greater in lower socioeconomic groups.
The Mixture Transition Distribution Model for High-Order Markov Chains and Non-Gaussian Time Series.
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Résumé Cette thèse de doctorat se fixe comme objectif général de définir la spécificité d'un espace urbain situé en centre-ville à travers sa dynamique sociale et interethnique. Il s'agit de relever les différentes formes et manifestations ethniques, mais également de comprendre la manière dont est vécue cette socialité, tout en tenant compte du contexte urbain dans lequel elles se situent. La particularité de ce travail est le fait de proposer une démarche alliant deux disciplines à savoir la géographie et la sociologie, dans le but de proposer une recherche transdisciplinaire, avec comme conséquence la mise en oeuvre d'une démarche commune nourrie des deux disciplines. Les quartiers ethniques situés en centre-ville ne se présentent pas comme des espaces figés, puisque des changements fréquents sont observés aussi bien au niveau de leur population que de l'affectation des locaux commerciaux et des logements. Ils semblent davantage se caractériser comme des « espaces à l'avenir indéterminé » dans le sens où leur avenir aussi bien au niveau de leur structure urbaine que de leurs rapports sociaux ne peut être prévisible et qu'ils sont par ailleurs susceptibles d'être soumis à de nombreux changements, d'où l'idée également d' « espaces en mutations ». Pour aborder ces thématiques de recherche, nous avons opté pour une étude fondée sur le principe de la représentation et de l'une des formes essentielles à travers lesquelles elles se produisent et se manifestent, à savoir les images. Cette recherche privilégie ainsi une analyse dynamique du phénomène interethnique, l'inscrivant dans le courant constructiviste qui s'intéresse notamment à l'étude des pratiques des acteurs sociaux et leurs représentations, dans le sens qu'elles sont le fruit d'une construction sociale. Dans ce type de démarche analytique, il s'agit de prendre en considération à la fois l'analyse du chercheur et la réalité objective et subjective du vécu des acteurs urbains qui regroupent les riverains, les commerçants, les membres associatifs, les politiques et les médias. C'est justement l'association de ces deux approches qui permet de définir un quartier urbain. Abstract "The spatial and social stakes of an interethnic dynamics in transition in the downtown area. The construction of the various forms of representations in order to define an urban quarter in Nice" The general objective of this PHD is to define the specificity of an urban space located in the downtown area with social and interethnic dynamics. Specifically the diverse ethnic form and sign to include the understanding mariner where society has lived in a specific urban context. The particularity of this work is to advance an analytic method using two disciplines: geography and sociology, in order to bring up a transdisciplinarian research with a common method. The ethnic quarters in the inner-city area are not presented as fixed spaces, since frequent changes were observed in the population level and at the allotment level of the commercial premises and the lodgings. Defined as "undetermined future spaces" as their future in the urban structure or the social relations can not be foresee and are supposed to be subjective to many changes. Therefore speaking of "mutations spaces". The option of this type of thematic research is the study of the principle of representation and essential form which shows and produces the images. Research promotes a dynamic analyses of the interethnic phenomena, inside the constructivist which is focused the practices of social actors, their own representations, and products of a social construction. The production of analytical approach is necessary in order to consider the analyses of the research worker and the objective and subjective reality of the life of the urban actors. It gathers the residents, tradesmen, members of associations, politicians and the press. The association of these types of approach define a urban quarter.
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Résumé Les mécanismes qui coordonnent la progression du cycle cellulaire lors de la méiose avec les événements du développement embryonnaire précoce, y compris la formation des axes de polarité embryonnaire, sont peu compris. Dans le zygote du vers Caenorhabditis elegans, les premiers signes de polarité Antéro-Postérieur (A-P) embryonnaire apparaissent après que la méiose soit terminée. La nature des protéines et des mécanismes moléculaires qui cassent la symétrie du zygote n'est pas connue. Nous démontrons que zyg-11 et cul-2 promeuvent la transition métaphase - anaphase et la sortie de la phase M lors de la seconde division méiotique. Nos résultats indiquent que ZYG-11 agit comme unité recrutant le substrat d'une ligase E3 comprennant CUL-2. Nos résultats montrent aussi que le délai de sortie de la phase M dépend de l'accumulation de la Cyclin B, CYB-3. Nous démontrons que dans des embryons zyg-11(RNAi) ou cul-2(RNAi), une polarité inversée est établie lors du délai de méiosis II. Enfin nous montrons que les défauts de cycle cellulaire et ceux de polarité peuvent être séparés. De plus, nous faisons apparaitre que l'établissement d'une polarité inversée pendant le délai de méiose II des embryons zyg-11(RNAi), comme l'établissement de la A-P polarité des embryons sauvage ne semblent pas requérir les microtubules. Nous montrons également les premiers résultats d'un crible deux hybrides ainsi qu'un crible génomique qui vise à identifier des gènes dont l'inactivation augmente ou supprime les défauts de mutants pour le gène zyg-11, afin d'identifier les gènes qui intéragissent avec ZYG-11 pour assumer ses deux fonctions séparables. Par conséquent, nos trouvailles suggèrent un modèle selon lequel ZYG-11 est une sous-unité qui recrute les substrats d'une ligase E3 basée sur CUL-2 qui promeut la progression du cycle cellulaire et empêche l'établissement de la polarité pendant la méiose II, et où le centrosome agit comme la clé qui polarise l'embryon à la fin de la méiose. Summary The mechanisms that couple meiotic cell cycle progression to subsequent developmental events, including specification of embryonic axes, are poorly understood. In the one cell stage embryos of Caenorhabditis elegans, the first signs of Antero-Posterior (A-P) polarity appear after meiosis completion. A centrosome ¬derived component breaks symmetry of the embryo, but the molecular nature of this polarity signal is not known. We established that zyg-11 and cul-2 promote the metaphase to anaphase transition and M phase exit at meiosis II. Our results indicate that ZYG-11 acts as a substrate recruitment subunit of a CUL-2-based E3 ligase. Moreover, we find that the delayed meiosis II exit of embryos lacking zyg-11 is caused by accumulation of the B-type cyclin, CYB-3. We demonstrate that inverted A-P polarity is established during the meiosis II delay in zyg-11(RNAi) and cul¬2(RNAi) embryos. Importantly, we demonstrate that the polarity defects following zyg-11 or cul-2 inactivation can be uncoupled from the cell cycle defects. Furthermore, we found that microtubules appear dispensable for inverted polarity during the meiosis II delay in zyg-11(RNAi) embryos, as well as for A-P polarity during the first mitotic cell cycle in wild-type embryos. We also show the initial results from a comprehensive yeast two hybrid, as well as an RNAi-based functional genomic enhancer and suppressor screen, that may lead to identification of proteins that interact with zyg-11 to ensure the two functions. Our findings suggest a model in which ZYG-11 is a substrate recruitment subunit of an CUL-2-based E3 ligase that promotes cell cycle progression and prevents polarity establishment during meiosis II, and in which the centrosome acts as a cue to polarize the embryo along the AP axis after exit from the meiotic cell cycle.