134 research outputs found

    Karst in France and UNESCO World Heritage

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    FrenchKarst covers the third of the territory. Because calcare­ous deposits date back to the Cambrian and are now located in tabular region as well as in tectonic areas, Frenchkarst is famous for its diversity. Large karst landscapes are well known, suchas Les Grands Causses, the Gorges du Tarn and the Gorges du Verdon. Resurgences suchas the Vaucluse Fountain and the spring of the Lez are very famous too. Karstic units can show very large dimensions: 400 km for the six hydrological net­works of the Pierre Saint-Martin, 104 km for the Arbas Moun­tain. Maximum depths can reachhighrecords, at Pierre Saint Martin, Berger Cave, Jean Bernard Cave and recently Mirolda Cave was acknowledged to reach1733-meter depth. Studies proceeded during the last century have revealed an im­portant cave fauna. Considering the heritage value of Frenchkarst, the key point is not only the presence of more than 160 decorated caves from Palaeolithic period but also the number of caves showing concretions. Moreover, a rare phenomenon has to be underlined: in Ariege, the Intermittent Fontestorbes Spring is the most regularly and completely studied resurgence in the world. This amount of exceptional features for these caves commands to organise studies and programmes to estab­lishconditions of a good conservation of this heritage for the next generations

    Application of time-series analyses to the hydrological functioning of an Alpine karstic system: the case of Bange-L'Eau-Morte

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    International audienceThis paper analyses the hydrological functioning of the Bange-L'Eau-Morte karstic system using classical and original techniques, recession curves, correlation and spectral analyses, noise analysis and wavelet analyses. The main characteristics that can be deduced are the recession coefficients, the dynamic volume of storage, the response time of the system, the quickflow and baseflow components and the snowmelt characteristics. The non-stationary and timescale-dependent behaviour of the system is studied and particular features of the runoff are shown. The step-by-step use of these different techniques provides a general methodology applicable to different karstic systems to provide quantifiable and objective criteria for differentiation and comparison of karstic systems. Keywords: karstic hydrology, Bauges mountains, recession curves, correlation and spectral analysis, wavelet analysis, snowmel

    Application of time-series analyses to the study of the hydrological functioning of an Alpine karstic system: the case of the Bange-L'Eau-Morte karstic system.

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    This paper analyses the hydrological functioning of the Bange-L'Eau-Morte karstic system using classical and original techniques, recession curves, correlation and spectral analyses, noise analysis and wavelet analyses. The main characteristics that can be deduced are the recession coefficients, the dynamic volume of storage, the response time of the system, the quickflow and baseflow components and the snowmelt characteristics. The non-stationary and timescale-dependent behaviour of the system is studied and particular features of the runoff are shown. The step-by-step use of these different techniques provides a general methodology applicable to different karstic systems to provide quantifiable and objective criteria for differentiation and comparison of karstic systems

    Niaux – Grotte de Niaux et rĂ©seau Clastres

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    Identifiant de l'opération archéologique : Date de l'opération : 1970 (FP) Inventeur(s) : Andrieux Claude ; Bakalowicz Michel ; D'Hulst Dominique ; Mangin Alain ; Rouch Raymond ; Laboratoire souterrain du CNRS (Moulins) Le réseau Clastres est isolé du reste des galeries de la grotte de Niaux par une série de voûtes mouillantes permanentes. Lors de sa découverte en 1970 (Clottes, 1973), et à l'initiative de Dr L. Pales, une étude climatique fut engagée par Claude Andrieux (CNRS, Moulis). Il ..

    Opto-thermo-mechanical numerical simulations of 3 different concepts of infrared achromatic phase shifters

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    The Darwin/TPF mission aims at detecting directly extra solar planets. It is based on the nulling interferometry, concept proposed by Bracewell in 1978, and developed since 1995 in several European and American laboratories. One of the key optical devices for this technique is the achromatic phase shifter (APS). This optical component is designed to produce a π phase shift over the whole Darwin spectral range (i.e. 6-18 ÎŒm), and will be experimentally tested on the NULLTIMATE consortium nulling test bench (LabĂšque et al). Three different concepts of APS are being simulated: dispersive plates focus crossing and field reversal. In this paper, we show how thermal, mechanical and optical models are merged into a single robust model, allowing a global numerical simulation of the optical component performances. We show how these simulations help us to optimizing the design and present results of the numerical model

    Neurobiology of suicide: do biomarkers exist?

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    Clinical risk factors have a low predictive value on suicide. This may explain the increasing interest in potential neurobiological correlates and specific heritable markers of suicide vulnerability. This review aims to present the current neurobiological findings that have been shown to be implicated in suicide completers and to discuss how postmortem studies may be useful in characterizing these individuals. Data on the role of the main neurobiological systems in suicidality, such as the neurotransmitter families, hypothalamic-pituitary-adrenal axis, neurotrophic factors, and polyamines, are exposed at the different biochemical, genetic, and epigenetic levels. Some neuroanatomic and neuropathological aspects as well as their in vivo morphological and functional neuroimaging correlates are also described. Except for the serotoninergic system, particularly with respect to the polymorphism of the gene coding for the serotonin transporter (5-HTTLPR) and brain-derived neurotrophic factor, data did not converge to produce a univocal consensus. The possible limitations of currently published studies are discussed, as well as the scope for long-term prospective studies

    Ventilatory Chaos Is Impaired in Carotid Atherosclerosis

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    Ventilatory chaos is strongly linked to the activity of central pattern generators, alone or influenced by respiratory or cardiovascular afferents. We hypothesized that carotid atherosclerosis should alter ventilatory chaos through baroreflex and autonomic nervous system dysfunctions. Chaotic dynamics of inspiratory flow was prospectively evaluated in 75 subjects undergoing carotid ultrasonography: 27 with severe carotid stenosis (>70%), 23 with moderate stenosis (<70%), and 25 controls. Chaos was characterized by the noise titration method, the correlation dimension and the largest Lyapunov exponent. Baroreflex sensitivity was estimated in the frequency domain. In the control group, 92% of the time series exhibit nonlinear deterministic chaos with positive noise limit, whereas only 68% had a positive noise limit value in the stenoses groups. Ventilatory chaos was impaired in the groups with carotid stenoses, with significant parallel decrease in the noise limit value, correlation dimension and largest Lyapunov exponent, as compared to controls. In multiple regression models, the percentage of carotid stenosis was the best in predicting the correlation dimension (p<0.001, adjusted R2: 0.35) and largest Lyapunov exponent (p<0.001, adjusted R2: 0.6). Baroreflex sensitivity also predicted the correlation dimension values (p = 0.05), and the LLE (p = 0.08). Plaque removal after carotid surgery reversed the loss of ventilatory complexity. To conclude, ventilatory chaos is impaired in carotid atherosclerosis. These findings depend on the severity of the stenosis, its localization, plaque surface and morphology features, and is independently associated with baroreflex sensitivity reduction. These findings should help to understand the determinants of ventilatory complexity and breathing control in pathological conditions

    Effect of population structure corrections on the results of association mapping tests in complex maize diversity panels

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    Association mapping of sequence polymorphisms underlying the phenotypic variability of quantitative agronomical traits is now a widely used method in plant genetics. However, due to the common presence of a complex genetic structure within the plant diversity panels, spurious associations are expected to be highly frequent. Several methods have thus been suggested to control for panel structure. They mainly rely on ad hoc criteria for selecting the number of ancestral groups; which is often not evident for the complex panels that are commonly used in maize. It was thus necessary to evaluate the effect of the selected structure models on the association mapping results. A real maize data set (342 maize inbred lines and 12,000 SNPs) was used for this study. The panel structure was estimated using both Bayesian and dimensional reduction methods, considering an increasing number of ancestral groups. Effect on association tests depends in particular on the number of ancestral groups and on the trait analyzed. The results also show that using a high number of ancestral groups leads to an over-corrected model in which all causal loci vanish. Finally the results of all models tested were combined in a meta-analysis approach. In this way, robust associations were highlighted for each analyzed trait

    Imaging Neuroscience opening editorial

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    In this editorial we introduce a new non-profit open access journal, Imaging Neuroscience. In April 2023, editors of the journals NeuroImage and NeuroImage:Reports resigned, and a month later launched Imaging Neuroscience. NeuroImage had long been the leading journal in the field of neuroimaging. While the move to fully open access in 2020 represented a positive step toward modern academic practices, the publication fee was set to a level that the editors found unethical and unsustainable. The publisher of NeuroImage, Elsevier, was unwilling to reduce the fee after much discussion. This led us to launch Imaging Neuroscience with MIT Press, intended to replace NeuroImage as our field’s leading journal, but with greater control by the neuroimaging academic community over publication fees and adoption of modern and ethical publishing practices
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