Flujo de un fluido viscoso a la entrada/salida de una cavidad anular de longitud finita

En este trabajo se presenta un procedimiento sencillo para imponer condiciones de borde en contornos artificiales a fin de resolver las ecuaciones de Navier-Stokes en presencia de efectos centrífugos. El análisis se concentra en el flujo de un fluido viscoso atrapado en una cavidad anular de longitud finita. El algoritmo se basa en desacoplar una componente estática del campo de presiones, la cual puede ser tratada con la aproximación penalizada. Los resultados numéricos exhiben un excelente acuerdo con resultados asintóticos obtenidos mediante una expansión basada en el método de las perturbaciones.Peer Reviewe

Flujo de un fluido viscoso a la entrada/salida de una cavidad anular de longitud finita

En este trabajo se presenta un procedimiento sencillo para imponer condiciones de borde en contornos artificiales a fin de resolver las ecuaciones de Navier-Stokes en presencia de efectos centrífugos. El análisis se concentra en el flujo de un fluido viscoso atrapado en una cavidad anular de longitud finita. El algoritmo se basa en desacoplar una componente estática del campo de presiones, la cual puede ser tratada con la aproximación penalizada. Los resultados numéricos exhiben un excelente acuerdo con resultados asintóticos obtenidos mediante una expansión basada en el método de las perturbaciones.Peer Reviewe

Natural gas and pricing mechanisms in Europe: what are the expectations for the coming years ?

In Europe, Natural gas pricing is a very interesting and complex subject. Today the European gas market is about to see a “BIG” change. In order to analyze the natural gas pricing in Europe and its evolution, we first need to understand that the European gas market pricing is divided in two main mechanisms. On one side we find the Oil-Indexed gas price, which is a long-term contract with some exporting countries like Russia, while on the other side the competitive Hub price based on supply and demand (spot ex: UK NBP and Dutch TTF) located in Europe. So, this drew to a battle between these two ways of pricing because the importers were buying gas on oil-linked deals that was higher than those paying at spot gas market levels (Hub). Through this decades pricing in Europe is the subject of many conversations, predictions and political debates. During my last year of Bachelor program, attending classes of “Commodity Trading” helped me to analyze and understand some of the actual debates concerning the commodities. I sow that the natural gas market in Europe was very complex and maybe close to a turning point. That is why, as a student, I have tried to understand this market. Finally, the purpose of this project is to analyze this market and try to understand what could happen with these two ways of pricing and follow the evolution of natural gas pricing in Europe. As well as predict what could happen in the next years taking into account the maximum of factors

Decreasing Insulin Sensitivity in Women Induces Alterations in LH Pulsatility.

Obesity is associated with neuroendocrine reproductive alterations and decreased fertility. The objective of the study was to gain insight into the neuroendocrine mechanisms implicated in these alterations. The effects on pulsatile LH secretion of 28 days of a hypercaloric diet were studied in lean and regularly cycling female volunteers. Approximately 50% extra calories (3 g sucrose/kg body weight per day and 1 g fat/kg body weight per day) were added to their individual daily requirements. Spontaneous and insulin-stimulated LH secretion was recorded on 2 different days, before and at the end of the caloric load. The hypercaloric diet induced an average weight gain of 2.0 ± 0.3 kg (P < .05), corresponding to a body mass index increase of 0.7 ± 0.1 kg/m(2) (P < .05). A concomitant decrease of 11.6% ± 4.6% in whole-body insulin sensitivity was also observed (δ = -1.6 ± 0.7 mg/kg · min glucose; P < .05). The frequency of spontaneous and insulin-stimulated pulsatile LH secretion was increased by 17.9% ± 9.0% and 26.5% ± 9.0%, respectively (both P < .05). Spontaneous LH peak amplitude was decreased by 26.5% ± 9.0% (δ = -0.7 ± 0.36 U/L; P < .05), a change correlated with insulin sensitivity. Short-term weight gain in normal female volunteers induces alterations of LH secretion reminiscent to those observed in obesity. A decrease in insulin sensitivity may constitute a mechanistic link between obesity and its associated neuroendocrine dysfunctions

Sofosbuvir and ribavirin before liver re-transplantation for graft failure due to recurrent hepatitis C: a case report.

BACKGROUND: Recurrent hepatitis C virus infection after liver transplantation is associated with reduced graft and patient survival. Re-transplantation for graft failure due to recurrent hepatitis C is controversial and not performed in all centers. CASE PRESENTATION: We describe a 54-year-old patient with hepatitis C virus genotype 1b infection and a null response to pegylated interferon-α and ribavirin who developed decompensated graft cirrhosis 6 years after a first liver transplantation. Treatment with sofosbuvir and ribavirin allowed for rapid negativation of serum HCV RNA and was well tolerated despite advanced liver and moderate renal dysfunction. Therapeutic drug monitoring did not reveal any clinically significant drug-drug interactions. Despite virological response, the patient remained severely decompensated and re-transplantation was performed after 46 days of undetectable serum HCV RNA. The patient is doing well 12 months after his second liver transplantation and remains free of hepatitis C virus. CONCLUSIONS: The use of directly acting antivirals may allow for successful liver re-transplantation for recipients who remain decompensated despite virological response and is likely to improve the outcome of liver re-transplantation for end-stage recurrent hepatitis C

Lac Blanc Pass: a natural wind-tunnel for studying drifting snow at 2700ma.s.l

International audienceThe investigation of the spatial variability of snow depth in high alpine areas is an important topic in snow hydrology, glacier and avalanche research and the transport of snow by wind is an important process for the distribution of snow in mountainous regions. That's why, for 25 years IRSTEA (previously Cemagref) and Météo France (Centre for the Study of Snow) have joined together in studying drifting snow at Col du Lac Blanc 2700 m a.s.l. near the Alpe d'Huez ski resort in the French Alps. Initially, the site was mainly equipped with conventional meteorological stations and a network of snow poles, in order to test numerical models of drifting snow Sytron (CEN) and NEMO (Cemagref). These models are complementary in terms of spatial and temporal scales: outputs of Sytron model will form the inputs of NEMO model. Then new sensors and technologies appeared which allow to develop new knowledge dealing with thresholds velocity according to morphological features of snow grains, snow flux profiles including parameters such as fall velocity and Schmidt number, histograms of particle widths, aerodynamic roughness, gust factors. More recently, the coupled snowpack/ atmosphere model Meso-NH/Crocus has been evaluated at the experimental site. At the same time, some tested sensors have been deployed in Adelie Land in Antarctica, where blowing snow accounts for a major component of the surface mass balance. Japanese and Austrian research teams have been accomodated at Lac Blanc Pass and new foreign teams are welcome. Initial observations continue. That's why Lac Blanc Pass is also a climatological reference for 25 years at 2700 m. Data are available

Chemogenetic E-MAP in Saccharomyces cerevisiae for identification of membrane transporters operating lipid flip flop

While most yeast enzymes for the biosynthesis of glycerophospholipids, sphingolipids and ergosterol are known, genes for several postulated transporters allowing the flopping of biosynthetic intermediates and newly made lipids from the cytosolic to the lumenal side of the membrane are still not identified. An E-MAP measuring the growth of 142'108 double mutants generated by systematically crossing 543 hypomorphic or deletion alleles in genes encoding multispan membrane proteins, both on media with or without an inhibitor of fatty acid synthesis, was generated. Flc proteins, represented by 4 homologous genes encoding presumed FAD or calcium transporters of the ER, have a severe depression of sphingolipid biosynthesis and elevated detergent sensitivity of the ER. FLC1, FLC2 and FLC3 are redundant in granting a common function, which remains essential even when the severe cell wall defect of flc mutants is compensated by osmotic support. Biochemical characterization of some other genetic interactions shows that Cst26 is the enzyme mainly responsible for the introduction of saturated very long chain fatty acids into phosphatidylinositol and that the GPI lipid remodelase Cwh43, responsible for introducing ceramides into GPI anchors having a C26:0 fatty acid in sn-2 of the glycerol moiety can also use lyso-GPI protein anchors and various base resistant lipids as substrates. Furthermore, we observe that adjacent deletions in several chromosomal regions show strong negative genetic interactions with a single gene on another chromosome suggesting the presence of undeclared suppressor mutations in certain chromosomal regions that need to be identified in order to yield meaningful E-map data

Tunneling-percolation origin of nonuniversality: theory and experiments

A vast class of disordered conducting-insulating compounds close to the percolation threshold is characterized by nonuniversal values of transport critical exponent t, in disagreement with the standard theory of percolation which predicts t = 2.0 for all three dimensional systems. Various models have been proposed in order to explain the origin of such universality breakdown. Among them, the tunneling-percolation model calls into play tunneling processes between conducting particles which, under some general circumstances, could lead to transport exponents dependent of the mean tunneling distance a. The validity of such theory could be tested by changing the parameter a by means of an applied mechanical strain. We have applied this idea to universal and nonuniversal RuO2-glass composites. We show that when t > 2 the measured piezoresistive response \Gamma, i. e., the relative change of resistivity under applied strain, diverges logarithmically at the percolation threshold, while for t = 2, \Gamma does not show an appreciable dependence upon the RuO2 volume fraction. These results are consistent with a mean tunneling dependence of the nonuniversal transport exponent as predicted by the tunneling-percolation model. The experimental results are compared with analytical and numerical calculations on a random-resistor network model of tunneling-percolation.Comment: 13 pages, 12 figure

Sensitive knowledge through an autoethnography of Contact Improvisation

Employing fieldwork in contact improvisation in Montreal, I will emphasise the sensitive knowledge we can gain from ethnographic methodologies. Based on an excerpt of my ethnographic account, I will highlight the benefits of auto-ethnography. As a social phenomenon, auto-ethnography allows the creation of a space to explore the conventions/taboos regulating touch and the redefinition of intimate boundaries that are shaped under circumstances of narrow proximity. In this research, auto-ethnography discloses aspects of the mindful body, such as the interrelatedness between touch, weight, intention and emotions. Fieldwork experience, by leaving a sensitive memory in the anthropologist’s body, shapes academic writing. Regarding this latter premise, I will show how it gains affect and sensoriality