Holocene Hydrological Changes Inferred from Alluvial Stream Entrenchment in North Tian Shan (Northwestern China)

We analyze the possible contribution of climate change or tectonics on fluvial incision from the study of a case example along the northern flank of Tian Shan. The rivers that exit the high range fed large alluvial fans by the end of the last glacial period. They have since deeply entrenched the piedmont by as much as 300 m. We have surveyed several terraces that were cut and abandoned during river entrenchment, providing information on intermediate positions of the riverbed during downcutting. They suggest a gradual decline in river slope during a major phase of incision throughout the Holocene. Tectonic uplift affects only a zone about 5 km wide, corresponding to a growing anticline, and is shown to account for about 10% of total incision. Incision was therefore most probably driven by climate change. From observed fluvial incision, we estimate the water discharge in excess of that needed to carry the sediments supplied by hillslope erosion in the headwaters. We used a model based on a transport‐limited erosion law. The model predicts relaxation process with entrenchment in the upper reach, downstream progradation of the incision‐sedimentation line, and a progressive decrease of river slope during incision consistent with our observations. According to this model, river slope might be used as a proxy for specific discharge and then for volumetric discharge, provided that an assumption is made about river width variations. We conclude that river incision in the study area has resulted from dynamic adjustment of the hydrological system to the settlement of wetter conditions in the early Holocene, when water discharge might have been about three times as high as at present. Then, a rather arid climate with enhanced seasonality has likely prevailed from the mid‐Holocene (~6 ka B.P.) until now

Chimeric hepatitis B virus/hepatitis C virus envelope proteins elicit broadly neutralizing antibodies and constitute a potential bivalent prophylactic vaccine.

International audienceThe development of a prophylactic vaccine against hepatitis C virus (HCV) has become an important medical priority, because 3-4 million new HCV infections are thought to occur each year worldwide. Hepatitis B virus (HBV) is another major human pathogen, but infections with this virus can be prevented with a safe, efficient vaccine, based on the remarkable ability of the envelope protein (S) of this virus to self-assemble into highly immunogenic subviral particles. Chimeric HBV-HCV envelope proteins in which the N-terminal transmembrane domain of S was replaced with the transmembrane domain of the HCV envelope proteins (E1 or E2) were efficiently coassembled with the wild-type HBV S protein into subviral particles. These chimeric particles presented the full-length E1 and E2 proteins from a genotype 1a virus in an appropriate conformation for formation of the E1-E2 heterodimer. Produced in stably transduced Chinese hamster ovary cells and used to immunize New Zealand rabbits, these particles induced a strong specific antibody (Ab) response against the HCV and HBV envelope proteins in immunized animals. Sera containing anti-E1 or anti-E2 Abs elicited by these particles neutralized infections with HCV pseudoparticles and cell-cultured viruses derived from different heterologous 1a, 1b, 2a, and 3 strains. Moreover, the anti-hepatitis B surface response induced by these chimeric particles was equivalent to the response induced by a commercial HBV vaccine. Conclusions: Our results provide support for approaches based on the development of bivalent HBV-HCV prophylactic vaccine candidates potentially able to prevent initial infection with either of these two hepatotropic viruses. (HEPATOLOGY 2013)

Modélisation de la propagation acoustique à moyenne distance du bruit des trains à grande vitesse

Cette étude a pour but d'identifier les paramètres influant sur la propagation acoustique du bruit émis par des trains à grande vitesse (TGV). Une campagne expérimentale est présentée, pendant laquelle des passages de TGV ont été enregistrés à des distances de la voie comprises entre 7,50 et 600 mètres. Des mesures de température et de vent ont également été réalisées pour caractériser les conditions atmosphériques pendant les passages. Les profils moyens de température et de vent sont estimés à partir des mesures à l'aide de la théorie de la similitude. Un modèle de propagation du bruit de TGV est ensuite présenté. Dans une première étape, le train est décomposé en un ensemble de sources équivalentes. Dans une seconde étape, un modèle de propagation analytique est utilisé pour calculer le niveau acoustique au récepteur. Les résultats du modèle sont comparés aux mesures en champ acoustique proche

Contribution à l’étude des sillons subverticaux intéressant des facettes interproximales

Des restes dentaires néandertaliens ont été mis au jour dans la grotte de Rochelot (Charente, France) reconnue comme un repaire d’hyènes. Deux dents, PM1 et PM2 gauches, présentent des sillons subverticaux sur leurs facettes d’attrition interproximales et antagonistes. L’étude macroscopique et microscopique (MEB) révèle que chaque sillon d’une facette interproximale présente une concordance d’orientation et de dimensions avec son antagoniste. L’analyse bibliographique et notre expérimentation sur des dents actuelles nous conduisent à l’élaboration d’une classification chronologique des phénomènes aboutissant à la formation ante mortem de ces sillons subverticaux.Neanderthal dental remains were discovered in the cave at Rochelot (Charente, France) which is known to have been inhabited by hyenas. Two left teeth, PM1 and PM2, presented subvertical grooves located on their antagonist interproximal facets. Macroscopic and microscopic examination revealed that each vertical groove of an interproximal facet resembled its antagonist groove. Bibliographical research and our experiments on modern teeth have led us to develop a chonological classification of the elements leading to the ante mortem formation of these subvertical grooves

Slip rates on the Chelungpu and Chushiang thrust faults inferred from a deformed strath terrace along the Dungpuna river, west central Taiwan

The Chelungpu fault produced the September 1999 M_w = 7.6 Chi-Chi earthquake, central Taiwan. The shortening rate accommodated by this structure, integrated over several seismic cycles, and its contribution to crustal shortening across the Taiwanese range have remained unresolved. To address the issues, we focus our study on the Chelungpu and Chushiang thrust faults within the southernmost portion of the Chi-Chi rupture area. Structural measurements and available seismic profiles are used to infer the subsurface geometry of structures. The Chushiang and Chelungpu faults appear as two splay faults branching onto a common ramp that further north connects only to the Chelungpu surface trace. We survey a deformed strath terrace along the Dungpuna river, buried under a 11,540 ± 309 years old fill deposit. Given this age, the dip angles of the faults, and the vertical throw determined from the offset of the strath terrace across the surface fault traces, we estimate slip rates of 12.9 ± 4.8 and 2.9 ± 1.6 mm/yr on the Chelungpu and Chushiang faults, respectively. These yield a total shortening rate of 15.8 ± 5.1 mm/yr to be absorbed on their common decollement at depth. This total value is an upper bound for the slip rate on the Chelungpu fault further north, where the Chushiang fault disappears and transfers shortening to adjacent faults. Combining these results with the recently constrained shortening rate on the Changhua blind thrust reveals that all these frontal faults presently absorb most of the long-term horizontal shortening across the Taiwanese range. They thus stand as the major sources of seismic hazards in this heavily populated area. The return period of earthquakes similar to the Chi-Chi event over a ∼80 km long stretch of the Western Foothills is estimated to be ~64 years. This value is an underestimate because it assumes that all the faults locked during the interseismic period slip only during such large events. Comparison with historical seismicity suggests that episodic aseismic deformation might also play a major role in accommodating shortening