29 research outputs found
Recent climatic and anthropogenic imprints on lacustrine systems in the Pyrenean Mountains inferred from minerogenic and organic clastic supply (Vicdessos valley, Pyrenees, France)
High-resolution seismic profiling has been combined with geochemical analyses of both watershed samples and five lacustrine cores retrieved from two natural lacustrine basins of glacial origin: Lake Majeur and Lake Sigriou (1630 m a.s.l. and 1995 m a.s.l., respectively, Eastern French Pyrenees). Identifying specific minerogenic and organic markers of autochthonous and allochthonous supply, data allow documenting past climatic and anthropogenic pressures. Over the past century, the lacustrine sediment of Lake Majeur has been essentially composed of algae, drastically contrasting with the natural sedimentary infill of the basin, mainly resulting from soil erosion from the mid–late Holocene. Since ad 1907, the Lake Majeur has been used for hydroelectricity production. Human-induced lake-level regulations, affecting up to 37% of the lacustrine surface, have increased by fourfold the accumulation rate of the lake and favoured water enrichment. Rubidium abundance within the lacustrine sediments of the two lakes reflects the mid–late Holocene palaeohydrology. After dam construction in ad 1907, greater quantities of rubidium found in Lake Majeur sedimentary infills indicate drier climatic periods, such as from ad 1975 to ad 1982, during which water reservoirs were particularly in demand. Inversely, before the dam was built, rubidium fluctuations were correlated with wetter conditions and hydrological events were recorded as sandy layers deposited by canyon reactivation, synchronous with European climatic deterioration phases. We notably document that the Mediaeval Climate Anomaly was interrupted by some humid periods dated c. ad 940, ad 1080, ad 1100 and ad 1250. We also date the onset of the ‘Little Ice Age’ c. ad 1360 and identify that this period was wetter after c. ad 1500
From fossils to mind
Fossil endocasts record features of brains from the past: size, shape, vasculature, and gyrification. These data, alongside experimental and comparative evidence, are needed to resolve questions about brain energetics, cognitive specializations, and developmental plasticity. Through the application of interdisciplinary techniques to the fossil record, paleoneurology has been leading major innovations. Neuroimaging is shedding light on fossil brain organization and behaviors. Inferences about the development and physiology of the brains of extinct species can be experimentally investigated through brain organoids and transgenic models based on ancient DNA. Phylogenetic comparative methods integrate data across species and associate genotypes to phenotypes, and brains to behaviors. Meanwhile, fossil and archeological discoveries continuously contribute new knowledge. Through cooperation, the scientific community can accelerate knowledge acquisition. Sharing digitized museum collections improves the availability of rare fossils and artifacts. Comparative neuroanatomical data are available through online databases, along with tools for their measurement and analysis. In the context of these advances, the paleoneurological record provides ample opportunity for future research. The biomedical and ecological sciences can benefit from paleoneurology's profound approach to understanding the mind as well as its novel research pipelines that correlate neuroanatomy to genes and behavior
Influence of peak flow changes on the macroinvertebrate drift downstream of a Brazilian hydroelectric dam
Discovery and measurement of optically pumped far-infrared laser emissions in (CD3OH)-C-13
We report the discovery of four laser emissions from the partially deuterated C-13 methanol isotope (CD3OH)-C-13 when optically pumped with a cw carbon dioxide (CO2) laser. The wavelengths of these lines, ranging from 45.3 to 108.9 mum, are reported along with their polarizations relative to the CO2 pump laser, operating pressure, and relative intensity. A three-laser heterodyne system was then used to measure the frequencies of eight optically pumped laser emissions from this methanol isotope. These emissions range from 53.4 to 126.1 mum and are reported with fractional uncertainties up to +/-2x10(-7).774182656156
New short-wavelength laser emissions from optically pumped (CD3OD)-C-13
We report the discovery of 15 new laser emissions from (CD3OD)-C-13 when optically pumped with a CW CO2 laser. The wavelengths of these lines, ranging from 57.5 to 135.2 mum, are reported along with their polarization relative to the CO2 PUMP laser, operating pressure and relative intensity. A three-laser heterodyne system was then used to measure the frequencies of 12 optically pumped laser emissions from this methanol isotope. These emissions range from 65.7 to 151.8 mum and are reported with fractional uncertainties up to +/-2 . 10(-7).38542943
Estimation des flux de matières en suspension lors des chasses hydrauliques de l'Arc de 2006 À 2011
International audienceEn rivière aménagée de montagne, l'optimisation du fonctionnement des ouvrages hydro‑éléctriques et de leur impact sur le cours d'eau passe par une meilleure compréhension des flux de matières en suspension (MES). Sur l'Arc en Maurienne, des chasses hydrauliques des trois principales retenues EDF sont réalisées tous les ans. Durant ces épisodes de chasse, les sédiments accumulés dans les retenues sont érodés et transportés en aval des ouvrages. Pour étudier la dynamique de ce transport, 5 campagnes de mesures ont été réalisées pendant les chasses de juin 2006, 2007, 2009, 2010 et 2011. Des mesures de débits et de concentrations en MES ont été réalisées en plusieurs sites de mesures entre le barrage de Saint‑Martin‑La‑Porte et la ville de Grenoble. Pour compléter ces données, un modèle hydraulique 1D a été réalisé (code MASCARET) sur l'ensemble du domaine d'étude, pour chacune des chasses. En 14 sites de mesures, des flux massiques de MES ont ainsi été calculés pour ces chasses hydrauliques. Un modèle de propagation de l'incertitude est proposé pour prendre en compte les principales sources d'erreur intervenant dans le calcul du flux global : méthode de mesure, modélisation hydraulique et hétérogénéité de la concentration en MES dans une section en travers. Il apparaît que la dynamique d'échange de MES avec le lit de la rivière et la quantité de sédiments remobilisés des retenues peuvent être très différents d'une année à l'autre, et les valeurs d'incertitude confirment les tendances globales de flux observées le long du système Arc‑Isère. Néanmoins, les bilans de masses d'un site à l'autre apparaissent plus délicats à interpréter
GIS tool to measure performance of winter highway operations
51 p.A five-year research effort (fifth-year funding through MRUTC) culminated in development, implementation, and installation of a GIS application for assessing performance of winter highway applications. The software accepts data recorded on board winter maintenance vehicles during operations and combines it with spatial data representing roadways and vehicle patrol sections. Analysts can then select among a number of performance measures and decision management tools for outputs from the system. Outputs are categorized according to labor, equipment, materials, and map displays that indicate vehicle routes and data collected along the way. The software, full user documentation, and necessary spatial databases were installed in two Wisconsin county highway department offices and at Wisconsin DOT headquarters. Training was provided to staff. The spatial databases were developed, and scrutinized for quality, by the research team from data provided by the counties. FGDC-standard metadata were included with the spatial databases. Documentation of the full system included internal and external technical documentation for the software. Final development of the application required refinement of performance measures, decision management tools, and the user interface. A number of previously unsolved technical problems also needed to be addressed. These included the "map-matching" problem in which moving vehicles must be tracked by roadway and patrol section by registering strings of two-dimensional vehicle coordinates to digital maps (spatial databases). The problem is exacerbated by errors in the coordinates and in the maps. A decision-rule algorithm was developed and tested against a number of available data sets. The algorithm resolves nearly all ambiguities encountered in the data. This algorithm is embedded in the installed version of the software. Testing revealed the limit (1:24,000) on source-scale of the spatial databases, needed to support the application. Future maintenance of both the software and the data raise technical and institutional issues that were identified and described by the research team. Recommendations concerning these issues are included in the final sections of this report.Wisconsin Department of Transportation; University of Wisconsin-Madison; 0092-05-2
Measurement of Laser Frequencies from CD3OH and CD3OD up to 8.6 THz
Twenty two laser frequencies, whose values range from 1.6 to 8.6 THz, have been measured for the first time using heterodyne techniques. These laser emissions were generated by an optically pumped molecular laser that used either CD3OH or CD3OD as its lasing medium. At least three of the observed laser emissions generated by CD3OH were discovered during this investigation and the first laser frequencies measured for CD3OH above 8 THz are reported. The laser frequencies were measured with fractional uncertainties up to ± 2 × 10−7, of sufficient accuracy to confirm two proposed far-infrared laser assignments. The offset frequency of the CO2 pump laser with respect to its center frequency was also measured for nearly all laser emissions generated by CD3OH
10 ans de mesures hautes fréquences des MES par turbidité sur le site Arc-Isère
National audienc