151 research outputs found
Hydrograph separation using isotopic, chemical and hydrological approaches (Strengbach catchment, France)
The streamflow components were determined in a small catchment located in Eastern France for a 40 mm rain event using isotopic and chemical tracing with particular focus on the spatial and temporal variations of catchment sources.
Precipitation, soil solution, springwater and streamwaters were sampled and analysed for stable water isotopes (18O and 2H), major chemical parameters (SO4, NO3, Cl2, Na1, K1, Ca21, Mg21, NH4, H1, H4SiO4, alkalinity and conductivity), dissolved organic carbon (DOC) and trace elements (Al, Rb, Sr, Ba, Pb and U). 18O, Si, DOC, Ba and U were finally selected to assess the different contributing sources using mass balance equations and end-member mixing diagrams.
Isotopic hydrograph separation shows that the pre-event water only contributes to 2% at the beginning of the stormflow to 13% at the main peak flow. DOC associated to Si and U to Ba allow to identify the different contributing areas (upper layers of the saturated areas, deep layers of the hillslope and rainwater). The streamflow (70%) originates from the deep layers of the hillslope, the remaining being supplied by the small saturated areas.
The combination of chemical (both trace and major elements) and isotopic tracers allows to identify the origin of water
pathways. During the first stage of the storm event, a significant part of the runoff (30±39%) comes from the small extended saturated areas located down part of the basin (overland runoff then groundwater ridging). During the second stage, the contribution of waters from the deep layers of the hillslope in the upper subcatchment becomes more significant. The final state is characterised by a balanced contribution between aquifers located in moraine and downslopes.
Indeed, this study demonstrates the interest of combining a variety of hydrometric data, geochemical and isotopic tracers to identify the components of the streamwater in such conditions
Electromagnetic-field distribution measurements in the soft s-ray range: full characterization of a soft x-ray laser beam
Includes bibliographical references (pages 183901-4).We report direct measurement of the electromagnetic-field spatial distribution in a neonlike Ar capillary discharge-driven soft x-ray laser beam. The wave front was fully characterized in a single shot using a Shack-Hartmann diffractive optics sensor. The wave front was observed to be dependent on the discharge pressure and capillary length, as a result of beam refraction variations in the capillary plasma. The results predict ~70% of the laser beam energy can be focused into an area 4 times the size of the diffraction-limited spot, reaching intensities of ~4 × 1013 W/cm2
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Collaborative development of diffraction-limited beamline optical systems at US DOE light sources
An ongoing collaboration among four US Department of Energy (DOE) National Laboratories has demonstrated key technology prototypes and software modeling tools required for new high-coherent flux beamline optical systems. New free electron laser (FEL) and diffraction-limited storage ring (DLSR) light sources demand wavefront preservation from source to sample to achieve and maintain optimal performance. Fine wavefront control was achieved using a novel, roomtemperature cooled mirror system called REAL (resistive element adjustable length) that combines cooling with applied, spatially variable auxiliary heating. Single-grating shearing interferometry (also called Talbot interferometry) and Hartmann wavefront sensors were developed and used for optical characterization and alignment on several beamlines, across a range of photon energies. Demonstrations of non-invasive hard x-ray wavefront sensing were performed using a thin diamond single-crystal as a beamsplitter
A coded aperture microscope for X-ray fluorescence full-field imaging
The design and construction of an instrument for full-field imaging of the X-ray fluorescence emitted by a fully illuminated sample are presented. The aim is to produce an X-ray microscope with a few micrometers spatial resolution, which does not need to scan the sample. Since the fluorescence from a spatially inhomogeneous sample may contain many fluorescence lines, the optic which will provide the magnification of the emissions must be achromatic, i.e. its optical properties must be energy-independent. The only optics which fulfill this requirement in the X-ray regime are mirrors and pinholes. The throughput of a simple pinhole is very low, so the concept of coded apertures is an attractive extension which improves the throughput by having many pinholes, and retains the achromatic property. Modified uniformly redundant arrays (MURAs) with 10 mu m openings and 50% open area have been fabricated using gold in a lithographic technique, fabricated on a 1 mu m-thick silicon nitride membrane. The gold is 25 mu m thick, offering good contrast up to 20keV. The silicon nitride is transparent down into the soft X-ray region. MURAs with various orders, from 19 up to 73, as well as their respective negative (a mask where open and closed positions are inversed compared with the original mask), have been made. Having both signs of mask will reduce near-field artifacts and make it possible to correct for any lack of contrast
An examination of the long-term CO records from MOPITT and IASI: comparison of retrieval methodology
International audienceCarbon monoxide (CO) is a key atmospheric compound that can be remotely sensed by satellite on the global scale. Fifteen years of continuous observations are now available from the MOPITT/Terra mission (2000 to present). Another fifteen and more years of observations will be provided by the IASI/MetOp instrument series (2007–2023>). In order to study long term variability and trends, a homogeneous record is required, which is not straightforward as the retrieved products are instrument and processing dependent. The present study aims at evaluating the consistency between the CO products derived from the MOPITT and IASI missions, both for total columns and vertical profiles, during a six year overlap period (2008–2013). The analysis is performed by first comparing the available 2013 versions of the retrieval algorithms, and second using a dedicated reprocessing of MOPITT CO profiles and columns based on the IASI a priori constraints. MOPITT v5T total columns are generally slightly higher over land (bias ranging from 0 to 13%) than IASI v20100815 data. When IASI and MOPITT data are retrieved with the same a priori constraints, correlation coefficients are slightly improved. Large discrepancies (total column bias over 15%) observed in the Northern Hemisphere during the winter months are reduced by a factor of 2 to 2.5. The detailed analysis of retrieved vertical profiles compared with collocated aircraft data from the MOZAIC-IAGOS network, illustrates the advantages and disadvantages of a constant vs. a variable a priori. On one hand, MOPITT agrees better with the aircraft profiles for observations with persisting high levels of CO throughout the year due to pollution or seasonal fire activity (because the climatology-based a priori is supposed to be closer to the real atmospheric state). On the other hand, IASI performs better when unexpected events leading to high levels of CO occur, due to the less constrained variance-covariance matrix
Carcinome folliculaire de la thyroïde au Maroc: Facteurs prédictifs de métastases
Introduction: Dans la majorité des études, l’analyse des facteurs pronostics du carcinome folliculaire de la thyroïde (CFT) a été faite conjointement avec ceux du carcinome papillaire (CPT), ce qui rend leur identification difficile. Le but de cette étude était de déterminer les facteurs prédictifs de survenue de métastases chez les patients atteints de CFT dans un centre de soins tertiaires au Maroc. Méthode : L’étude incluait les patients atteints de CFT non métastatiques au moment du diagnostic suivis au service de médecine nucléaire du CHU Ibn Rochd de Casablanca entre Janvier 2005 et Décembre 2012. Les caractéristiques clinico-pathologique, les traitements reçus et leur résultat ont été examinés en comparaison avec un échantillon de carcinome papillaire traité durant la même période. Une analyse univariée des caractéristiques des patients a été effectuée à l'aide du logiciel IBM SPSS. Résultats : Soixante-treize patients ont été inclus dans l’étude. L'âge moyen était de 51 ans (± 14), le sexe ratio (H / F) était de 0,17. Lors de l’analyse statistique, un âge supérieur à 45 ans (p=0,002) ; une taille tumorale supérieure à 5 cm (p=0,04), la multifocalité (p=0,04), les emboles vasculaires (p=0,02), un taux de thyroglobuline en défreination élevé (p=0,000) et un stade initial avancé (p=0,000) étaient retenus comme facteurs prédictifs de survenue de métastases à distance. Par rapport au CPT, le CFT était corrélé à un risque plus élevé de métastases (p = 0,000)
Tricuspid valve myxoma in a patient with congestive heart failure
Myxomas are the most frequent benign primary cardiac tumours (50% of benign heart tumours). This kind of tumour is most likely to be localized in the left atrium, followed by the right atrium, right ventricle and left ventricle. Quite exceptional is the presence of a myxoma originating from the tricuspid valve or from the Eustachian valve. We describe the case of a woman with moderate dyspnoea of unknown origin and the presence of tricuspid myxoma who underwent tricuspid valve curettage
Cdk1-mediated threonine phosphorylation of Sam68 modulates its RNA binding, alternative splicing activity and cellular functions
Sam68, also known as KHDRBS1, is a member of the STAR family of proteins that directly link signal transduction with post-transcriptional gene regulation. Sam68 controls the alternative splicing of many oncogenic proteins and its role is modulated by post-translational modifications, including serine/threonine phosphorylation, that differ at various stages of the cell cycle. However, the molecular basis and mechanisms of these modulations remain largely unknown. Here, we combined mass spectrometry, nuclear magnetic resonance spectroscopy and cell biology techniques to provide a comprehensive post-translational modification mapping of Sam68 at different stages of the cell cycle in HEK293 and HCT116 cells. We established that Sam68 is specifically phosphorylated at T33 and T317 by Cdk1, and demonstrated that these phosphorylation events reduce the binding of Sam68 to RNA, control its cellular localization and reduce its alternative splicing activity, leading to a reduction in the induction of apoptosis and an increase in the proliferation of HCT116 cells
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Radiative forcing of climate change from the Copernicus reanalysis of atmospheric composition
Radiative forcing provides an important basis for understanding and predicting global climate changes, but its quantification has historically been done independently for different forcing agents, involved observations to varying degrees, and studies have not always included a detailed analysis of uncertainties. The Copernicus Atmosphere Monitoring Service reanalysis is an optimal combination of modelling and observations of atmospheric composition. It provides a unique opportunity to rely on observations to quantify the monthly and spatially resolved global distributions of radiative forcing consistently for six of the largest forcing agents: carbon dioxide, methane, tropospheric ozone, stratospheric ozone, aerosol-radiation interactions, and aerosol-cloud interactions. These radiative forcing estimates account for adjustments in stratospheric temperatures, but do not account for rapid adjustments in the troposphere. On a global average and over the period 2003—2017, stratospherically adjusted radiative forcing of carbon dioxide has averaged +1.89 W m−2 (5-95% confidence interval: 1.50 to 2.29 W m−2) relative to 1750 and increased at a rate of 18% per decade. The corresponding values for methane are +0.46 (0.36 to 0.56) W m−2 and 4% per decade, but with a clear acceleration since 2007. Ozone radiative forcing averages +0.32 (0 to 0.64) W m−2, almost entirely contributed by tropospheric ozone since stratospheric ozone radiative forcing is only +0.003 W m−2. Aerosol radiative forcing averages −1.25 (−1.98 to −0.52) W m−2, with aerosol-radiation interactions contributing −0.56 W m−2 and aerosol-cloud interactions contributing −0.69 W m−2 to the global average. Both have been relatively stable since 2003. Taking the six forcing agents together, there no indication of a sustained slowdown or acceleration in the rate of increase in anthropogenic radiative forcing over the period. These ongoing radiative forcing estimates will monitor the impact on the Earth’s energy budget of the dramatic emission reductions towards net-zero that are needed to limit surface temperature warming to the Paris Agreement temperature targets. Indeed, such impacts should be clearly manifested in radiative forcing before being clear in the temperature record. In addition, this radiative forcing dataset can provide the input distributions needed by researchers involved in monitoring of climate change, detection and attribution, interannual to decadal prediction, and integrated assessment modelling. The data generated by this work are available at https://doi.org/10.24380/ads.1hj3y896 (Bellouin et al., 2020)
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