Solar wind dynamic pressure and electric field as the main factors controlling Saturn's aurorae

The interaction of the solar wind with Earth's magnetosphere gives rise to the bright polar aurorae and to geomagnetic storms(1), but the relation between the solar wind and the dynamics of the outer planets' magnetospheres is poorly understood. Jupiter's magnetospheric dynamics and aurorae are dominated by processes internal to the jovian system(2), whereas Saturn's magnetosphere has generally been considered to have both internal and solar-wind-driven processes. This hypothesis, however, is tentative because of limited simultaneous solar wind and magnetospheric measurements. Here we report solar wind measurements, immediately upstream of Saturn, over a one-month period. When combined with simultaneous ultraviolet imaging(3) we find that, unlike Jupiter, Saturn's aurorae respond strongly to solar wind conditions. But in contrast to Earth, the main controlling factor appears to be solar wind dynamic pressure and electric field, with the orientation of the interplanetary magnetic field playing a much more limited role. Saturn's magnetosphere is, therefore, strongly driven by the solar wind, but the solar wind conditions that drive it differ from those that drive the Earth's magnetosphere.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62975/1/nature03333.pd

Testing macroecological abundance patterns: The relationship between local abundance and range size, range position and climatic suitability among European vascular plants

Aim: A fundamental question in macroecology centres around understanding the relationship between species' local abundance and their distribution in geographical and climatic space (i.e. the multi‐dimensional climatic space or climatic niche). Here, we tested three macroecological hypotheses that link local abundance to the following range properties: (a) the abundance-range size relationship, (b) the abundance-range centre relationship and (c) the abundance-suitability relationship. Location: Europe. Taxon: Vascular plants. Methods: Distribution range maps were extracted from the Chorological Database Halle to derive information on the range and niche sizes of 517 European vascular plant species. To estimate local abundance, we assessed samples from 744,513 vegetation plots in the European Vegetation Archive, where local species' abundance is available as plant cover per plot. We then calculated the 'centrality', that is, the distance between the location of the abundance observation and each species' range centre in geographical and climatic space. The climatic suitability of plot locations was estimated using coarse‐grain species distribution models (SDMs). The relationships between centrality or climatic suitability with abundance was tested using linear models and quantile regression. We summarized the overall trend across species' regression slopes from linear models and quantile regression using a meta‐analytical approach. Results: We did not detect any positive relationships between a species' mean local abundance and the size of its geographical range or climatic niche. Contrasting yet significant correlations were detected between abundance and centrality or climatic suitability among species. Main conclusions: Our results do not provide unequivocal support for any of the relationships tested, demonstrating that determining properties of species' distributions at large grains and extents might be of limited use for predicting local abundance, including current SDM approaches. We conclude that environmental factors influencing individual performance and local abundance are likely to differ from those factors driving plant species' distribution at coarse resolution and broad geographical extents

L’intention de réaliser un mouvement volontaire préparé de manière sélective les aires corticales motrices du muscle prime mover

info:eu-repo/semantics/publishe

Endobronchial ultrasonography: a novel technique for investigation of the mediastinum

peer reviewedMediastin pathology includes primary lesion and lymph node invasion. The exploration of this anatomical region remains difficult and even hazardous, particularly to obtain histological biopsies. No invasive diagnostic exploration (thorax tomodensitometry and positron emission tomography) allows a histological precision, so mediastinoscopy remains the gold standard in the mediastinum investigation. However, it is not deprived of risk. Recently, guided biopsies and real-time transbronchial needle aspiration by endobronchial ultrasonography (EBUS) have been shown to increase the diagnostic yield over conventional bronchoscopic techniques. Therefore, EBUS is a suitable alternative to mediastinoscopy in the diagnosis of pulmonary or extra-thoracic malignancy, in the staging of mediastinal lymphadenopathy, and in the evaluation of mediastinal response after induction therapy. In the present paper, we present this new diagnostic approach and clarify the current indications of EBUS

Habits and risk perception associated with sun exposure in vitiligo patients according to their participation in a patients’ organization

International audienc

A Comparison of FUV Auroral Emissions During the April 2002 Events as seen by the IMAGE/FUV and TIMED/GUVI Instruments

The auroral emissions that resulted from the series of solar particle events and magnetic storms during 14-24 April 2002 provide an excellent data set for the cross-comparison of the IMAGE/FUV and TIMED/GUVI auroral imagers. The IMAGE/FUV instrument comprises the SI spectral imager (121.8 nm and 135.6 nm) and the WIC imaging photometer (LBH) and observes the entire Earth from high Earth orbit. The TIMED/GUVI spectral imager (121.6 nm, 130.4 nm, 135.6 nm, LBH short, and LBH long) scans a nadir-to-limb swath from low Earth orbit. Although there is a large difference in spatial resolution, preliminary comparison of simultaneously-observed diffuse auroral emissions indicates fairly good agreement between the calibrated brightnesses determined for common spectral features. We will present a detailed simulation of one or more of the April 2002 events as seen by each imager to determine if a single description of the auroral precipitation can self-consistently account for the proton- and electron-generated FUV emissions observed from the two spacecraft