Datations radiométriques de l'extinction des grandes faunes pléistocènes au Pérou.

International audienceThe discovery in northern Peru of fossil deposits belonging to large mammals allows the dating of the extinction of this fauna. The method based on desequilibrium within the uranium family (230Th/234U) was used. The extinction occurred at the end of the Pleistocene (15-16 Kyrs Cal BP) and is contemporaneous with the beginning of the deglaciation. Moreover, this dating, compared with the results of excavations of palaeo-indian "Paijan" sites, indicates that human groups in Peru did not play a significant role in the extinction of this large fauna.Les restes osseux découverts dans les gisements paléontologiques à grands mammifères du Pérou ont pu être datés par la méthode fondée sur les déséquilibres de la famille de l'uranium (230Th-234U). L'extinction de cette grande faune coïncide avec la fin du Pléistocène et le début de la déglaciation (15-16 Ka Cal BP). La chronologie et les fouilles menées dans les gisements paijaniens montrent que les groupes humains préhistoriques au Pérou ne semblent pas avoir joué un rôle significatif dans cette extinction qui semble être la conséquence de changements climatiques importants dans cette région

Unsupervised host behavior classification from connection patterns

International audienceA novel host behavior classification approach is proposed as a preliminary step toward traffic classification and anomaly detection in network communication. Though many attempts described in the literature were devoted to flow or application classifications, these approaches are not always adaptable to operational constraints of traffic monitoring (expected to work even without packet payload, without bidirectionality, on highspeed networks or from flow reports only...). Instead, the classification proposed here relies on the leading idea that traffic is relevantly analyzed in terms of host typical behaviors: typical connection patterns of both legitimate applications (data sharing, downloading,...) and anomalous (eventually aggressive) behaviors are obtained by profiling traffic at the host level using unsupervised statistical classification. Classification at the host level is not reducible to flow or application classification, and neither is the contrary: they are different operations which might have complementary roles in network management. The proposed host classification is based on a nine-dimensional feature space evaluating host Internet connectivity, dispersion and exchanged traffic content. A Minimum Spanning Tree (MST) clustering technique is developed that does not require any supervised learning step to produce a set of statistically established typical host behaviors. Not relying on a priori defined classes of known behaviors enables the procedure to discover new host behaviors, that potentially were never observed before. This procedure is applied to traffic collected over the entire year 2008 on a transpacific (Japan/USA) link. A cross-validation of this unsupervised classification against a classical port-based inspection and a state-of-the-art method provides assessment of the meaningfulness and the relevance of the obtained classes for host behaviors

Contrasted morphosedimentary activity of the lower Kert River (northeastern Morocco) during the Late Pleistocene and the Holocene. Possible impact of bioclimatic variations and human action

International audienceFrom field observations in the lower Kert valley and 16 radiocarbon dating measurements, six alluvial units (UF1 to UF6) deposited since about 30,000 years BP have been identified, comprising 18 lithofacies and separated by six incision stages resulting in three alluvial terraces (T1 to T3). While the Late Pleistocene is mainly marked by sedimentary accretion (UF1 forming part of T1), the Holocene is marked by the alternation of major incision (I2, I3 and I4) and accretion (UF2 and UF3) stages, with roughly similar height ranges, between the current river level and polyphased T1 surface. During the Lower and Middle Holocene, this complex morphosedimentary evolution could have been the result of contrasted bioclimatic trends that did not appear during the Late Pleistocene. Human activities modified the earth surface conditions, intermittently during the Middle Holocene, and during the Upper Holocene, inducing new responses from the fluvial geosystem to the environment

Western equatorial African forest-savanna mosaics: a legacy of late Holocene climatic change?

Past vegetation and climate changes reconstructed using two pollen records from Lakes Maridor and Nguène, located in the coastal savannas and inland rainforest of Gabon, respectively, provide new insights into the environmental history of western equatorial African rainforests during the last 4500 cal yr BP. These pollen records indicate that the coastal savannas of western equatorial Africa did not exist during the mid-Holocene and instead the region was covered by evergreen rainforests. From ca. 4000 cal yr BP a progressive decline of inland evergreen rainforest, accompanied by the expansion of semi-deciduous rainforest, occurred synchronously with grassland colonisation in the coastal region of Gabon. The contraction of moist evergreen rainforest and the establishment of coastal savannas in Gabon suggest decreasing humidity from ca. 4000 cal yr BP. The marked reduction in evergreen rainforest and subsequent savanna expansion was followed from 2700 cal yr BP by the colonization of secondary forests dominated by the palm, <i>Elaeis guineensis</i>, and the shrub, <i>Alchornea cordifolia</i> (Euphorbiaceae). A return to wetter climatic conditions from about 1400 cal yr BP led to the renewed spread of evergreen rainforest inland, whereas a forest-savanna mosaic still persists in the coastal region. There is no evidence to suggest that the major environmental changes observed were driven by human impact

Holocene landscape and human modesof occupation in the Kura Valley (Azerbaijan)

International audienceGoy Tepe, 291 where they are dated to the Neolithic. This similarity between the two periods contributes to the discussion on the heritage of Neolithic populations to Chalcolithic ones in our area. The main raw material used is bone. Quite often people extracted this material from domesticated animals (ovi-caprines) at hand, but large ruminants , wild or domesticated, were also used. The selections, probably oriented by technical advantages , are quite systematic: metapods of small ruminants for awls, scapulae of big mammals for shovels. The main characteristics of the tools demonstrate a will to produce in a quick but efficient way: quite often tools are made on plain bones only lightly shaped, while rapid techniques are frequently used (percussion, abrasion). Part of the blanks obtained by percussion are probably the result of a proper, well controlled débitage: the blanks are fairly long and regular. We cannot exclude that others, with more random shapes, were collected from kitchen wastes. As has been observed on grinding materials 292 and in several areas of the site, ochre is quite often attested on bone tools. It would be useful to analyse this red material found on stones and bones and to determine, through a joint study by specialists, its possible uses and the links between two industries. Similarly, the discovery of bone shovels that were possibly used to work the earth needs further cross studies and experimentations. Part IV: Studies concerning the three areas of the Middle Kura Valley Bertille Lyonnet and Barbara Helwing With this section of our work we enter into the studies dealing with the three geographic areas of the Middle Kura Valley. In this part of the project, our specialists study and compare the material culture, or the landscape and geomorphology of the three places in order to detect differences and similarities and the chronological development. This phase of our research is just at its very beginning, and most of the time it was possible to work on only two areas and not yet on all the collections. Nevertheless , the project gives a hint at the potential of such studies, which will aid in a better determination of the local cultures, of their local development, and of their relations between themselves and/or with other regions further away. We will first present the results concerning the general landscape and environmental conditions, and then comparative studies on the material culture

Unraveling the clonal hierarchy of somatic genomic aberrations

Defining the chronology of molecular alterations may identify milestones in carcinogenesis. To unravel the temporal evolution of aberrations from clinical tumors, we developed CLONET, which upon estimation of tumor admixture and ploidy infers the clonal hierarchy of genomic aberrations. Comparative analysis across 100 sequenced genomes from prostate, melanoma, and lung cancers established diverse evolutionary hierarchies, demonstrating the early disruption of tumor-specific pathways. The analyses highlight the diversity of clonal evolution within and across tumor types that might be informative for risk stratification and patient selection for targeted therapies. CLONET addresses heterogeneous clinical samples seen in the setting of precision medicine. Electronic supplementary material The online version of this article (doi:10.1186/s13059-014-0439-6) contains supplementary material, which is available to authorized users