Strong anisotropic influence of local-field effects on the dielectric response of {\alpha}-MoO3

Dielectric properties of {\alpha}-MoO3 are investigated by a combination of valence electron-energy loss spectroscopy and ab initio calculation at the random phase approximation level with the inclusion of local-field effects (LFE). A meticulous comparison between experimental and calculated spectra is performed in order to interpret calculated dielectric properties. The dielectric function of MoO3 has been obtained along the three axes and the importance of LFE has been shown. In particular, taking into account LFE is shown to be essential to describe properly the intensity and position of the Mo-N2,3 edges as well as the low energy part of the spectrum. A detailed study of the energy-loss function in connection with the dielectric response function also shows that the strong anisotropy of the energy-loss function of {\alpha}-MoO3 is driven by an anisotropic influence of LFE. These LFE significantly dampen a large peak in {\epsilon}2, but only along the [010] direction. Thanks to a detailed analysis at specific k-points of the orbitals involved in this transition, the origin of this peak has not only been evidenced but a connection between the inhomogeneity of the electron density and the anisotropic influence of local-field effects has also been established. More specifically, this anisotropy is governed by a strongly inhomogeneous spatial distribution of the empty states. This depletion of the empty states is localized around the terminal oxygens and accentuates the electron inhomogeneity.Comment: Supplemental Material include

Dynamic range optimisation of CMOS image sensors dedicated to space applications

Nowadays, CMOS image sensors are widely considered for space applications. Their performances have been significantly enhanced with the use of CIS (CMOS Image Sensor) processes in term of dark current, quantum efficiency and conversion gain. Dynamic Range (DR) remains an important parameter for a lot of applications. Most of the dynamic range limitation of CMOS image sensors comes from the pixel. During work performed in collaboration with EADS Astrium, SUPAERO/CIMI laboratory has studied different ways to improve dynamic range and test structures have been developed to perform analysis and characterisation. A first way to improve dynamic range will be described, consisting in improving the voltage swing at the pixel output. Test vehicles and process modifications made to improve voltage swing will be depicted. We have demonstrated a voltage swing improvement more than 30%. A second way to improve dynamic range is to reduce readout noise A new readout architecture has been developed to perform a correlated double sampling readout. Strong readout noise reduction will be demonstrated by measurements performed on our test vehicle. A third way to improve dynamic range is to control conversion gain value. Indeed, in 3 TMOS pixel structure, dynamic range is related to conversion gain through reset noise which is dependant of photodiode capacitance. Decrease and increase of conversion gain have been performed with different design techniques. A good control of the conversion gain will be demonstrated with variation in the range of 0.05 to 3 of initial conversion gain

Plasma amino-acid determinations by reversed-phase HPLC: Improvement of the orthophthalaldehyde method and comparison with ion exchange chromatography

Reversed-phase high performance liquid chromatographic (RPHPLC) determination of amino-acids with on-line pre-column ortho-phthalaldehyde (OPA) derivatization and fluorescence detection is rapid and sensitive. However, high-performance ionexchange chromatography (HP-IEC) with post-column ninhydrine reaction is the most widely used amino-acid (AA) assay for biological samples. These two methods have been compared for the determination of individual plasma AA concentrations

Etude biochimique d'un cytochrome P450 de cerveau humain (le CYP2U1)

Parmi les 57 cytochromes P450 identifiés lors du séquençage complet du génome humain, on en dénombre environ 15 dont on ne connaît pratiquement rien de leurs rôles physiologiques, de leurs substrats, et de leurs structures, d où le nom de P450 orphelins . Le CYP2U1 est l un des cytochromes P450 les plus fortement exprimé au niveau du cerveau et du cervelet mais c est aussi l un des plus conservé parmi les différentes espèces du règne animal. Ce travail de thèse a tout d abord consisté à optimiser les conditions d expression du CYP2U1 sous une forme active. Un premier système d expression dans la levure Saccharomyces Cerevisiae a permis une production d un complexe CYP2U1-P450 réductase catalytiquement actif permettant des études de recherche de substrat. Un second système d expression dans Escherichia Coli devrait permettre d obtenir de plus grandes quantités d enzyme soluble destinée à des études structurales. Dans un second temps, une recherche de substrats a été effectuée à l aide d analyse d incubats par chromatographie liquide couplée à une détection par spectrométrie de masse. A ce jour, un screening dirigé de plus de soixante-dix molécules, substrats de P450s de la famille 2, a permis d identifier les premiers substrats exogènes du CYP2U1, les analogues de terfénadone et la débrisoquine. D autre part, une étude par modélisation moléculaire de la structure du CYP2U1 a été effectuée. Cette étude montre que le CYP2U1 diffère de tous les autres P450s par la présence d un insert très spécifique dans son domaine N-terminal. Des modèles par homologie basés sur les structures cristallographiques des P450s de la famille 2 ont été construits. Ces modèles ont été validés par dynamique moléculaire et ont permis de proposer un mode d interaction avec la membrane, d identifier la position des canaux d accès ainsi que de déterminer la topologie du site actif. Enfin, un docking des premiers substrats exogènes au sein du site actif du CYP2U1 a permis de confirmer la régioselectivité des hydroxylations catalysées par le CYP2U1.Among the 57 human cytochrome P450 genes that have been identified; substrates, structure and physiologic role of 15 of them is practically unknown. They are called orphan. One of them, CYP2U1 is one of the most expressed cytochrome P450 in the brain and in the cerebellum but also one of the most conserved isoform in the all animal kingdom. This manuscript first describes the optimization of the heterologous expression of an active form of CYP2U1. Expression in a eukaryotic host, yeast Saccharomyces Cerevisiae first allows the production of a catalytic active CYP2U1-P450 reductase complex needed for substrate screening. Another expression system in a prokaryote host Escherichia Coli will allow higher production rate of a truncated and soluble form of the protein which will permit structural studies. Then a directed substrate screening was performed with the liquid chromatography mass spectrometry analysis of CYP2U1 incubations. To date, 70 molecules, CYP2 family substrates, were tested that allow the identification of the two first exogenous CYP2U1 substrates: débrisoquine and terfenadone analogs. A structural study was achieved using a homology tridimensional model of the enzyme. We have found that CYP2U1 is longer than the other human CYPs, with an N-terminal 20 amino acids insertion, located after the helical membrane spanning domain. Structural models were built using six crystallized human CYP2s as templates. Molecular dynamics experiments in membrane suggested a specific interaction with the membrane. The active site topology and the access channels were also determined and a docking of the two first exogenous CYP2U1 substrates was performed in order to confirm the regioselective hydroxylation activities observed in vitro.PARIS5-Bibliotheque electronique (751069902) / SudocPARIS-BIUM-Bib. électronique (751069903) / SudocSudocFranceF

Uncovering the minor contribution of land-cover change in upland forests to the net carbon footprint of a boreal hydroelectric reservoir

Hydropower in boreal conditions is generally considered the energy source emitting the least greenhouse gas per kilowatt-hour during its life cycle. The purpose of this study was to assess the relative contribution of the land-use change on the modification of the carbon sinks and sources following the flooding of upland forested territories to create the Eastmain-1 hydroelectric reservoir in Quebec’s boreal forest using Carbon Budget Model of the Canadian Forest Sector. Results suggest a carbon sink loss after 100 yr of 300,000 ± 100,000 Mg CO2 equivalents (CO2e). A wildfire sensitivity analysis revealed that the ecosystem would have acted as a carbon sink as long as <75% of the territory had burned over the 100-yr-long period. Our long-term net carbon flux estimate resulted in emissions of 4 ± 2 g CO2e kWh−1 as a contribution to the carbon footprint calculation, one-eighth what was obtained in a recent study that used less precise and less sensitive estimates. Consequently, this study significantly reduces the reported net carbon footprint of this reservoir and reveals how negligible the relative contribution of the land-use change in upland forests to the total net carbon footprint of a hydroelectric reservoir in the boreal zone can be

Management of Esophageal Carcinoma Associated with Cirrhosis: A Retrospective Case-Control Analysis

Objectives. Esophageal carcinoma and cirrhosis have the overlapping etiologic factors. Methods. In a retrospective analysis conducted in 2 Breton institutions we wanted to asses the frequency of this association and the outcome of these patients in a case-control study where each case (cirrhosis and esophageal cancer) was paired with two controls (esophageal cancer). Results. In a 10-year period, we have treated 958 esophageal cancer patients; 26 (2.7%) had a cirrhosis. The same treatments were proposed to the 2 groups; cases received nonsignificantly different radiation and chemotherapy dose than controls. Severe toxicities and deaths were more frequent among the cases. At the end of the treatment 58% of the cases and 67% of the controls were in complete remission; median and 2-year survival were not different between the 2 groups. All 4 Child-Pugh B class patients experienced severe side effects and 2 died during the treatment. Conclusions. This association is surprisingly infrequent in our population! Child-Pugh B patients had a dismal prognosis and a bad tolerance to radiochemotherapy; Child-Pugh A patients have the same tolerance and the same prognosis as controls and the evidence of a well-compensated cirrhosis has not modified our medical options

The Disability Creation Process Model: A Comprehensive Explanation of Disabling Situations as a Guide to Developing Policy and Service Programs

Understanding disability remains a challenge. Although the international community has largely embraced the idea that disability is the product of social and environmental practices, society still lacks good conceptual frameworks. In an era when the rights of persons with disabilities have been enshrined in international and national laws, such frameworks have become a necessity. Within the province of Quebec, Canada, the Disability Creation Process (DCP) model has served such a role. Furthermore, recent efforts to enrich the model enhance the applicability of this powerful tool to a broader range of contexts. As a result, the DCP model could be used more widely than it is today. In this paper we provide the foundations of the approach encapsulated by the model and explain how its usage guides policy development and service delivery within the province of Quebec. We also highlight its forward-looking capacities

Utility of Quantitative 99mTc-MAA SPECT/CT for 90yttrium-Labelled Microsphere Treatment Planning: Calculating Vascularized Hepatic Volume and Dosimetric Approach

Objectives. The aim of this study was to assess the effectiveness of SPECT/CT for volume measurements and to report a case illustrating the major impact of SPECT/CT in calculating the vascularized liver volume and dosimetry prior to injecting radiolabelled yttrium-90 microspheres (Therasphere). Materials and Methods. This was a phantom study, involving volume measurements carried out by two operators using SPECT and SPECT/CT images. The percentage of error for each method was calculated, and interobserver reproducibility was evaluated. A treatment using Therasphere was planned in a patient with three hepatic arteries, and the quantitative analysis of SPECT/CT for this patient is provided. Results. SPECT/CT volume measurements proved to be accurate (mean error <6% for volumes ≥16 cm3) and reproductive (interobserver agreement = 0.9). In the case report, 99mTc-MAA SPECT/CT identified a large liver volume, not previously identified with angiography, which was shown to be vascularized after selective MAA injection into an arterial branch, resulting in a large modification in the activity of Therasphere used. Conclusions. MAA SPECT/CT is accurate for vascularized liver volume measurements, providing a valuable contribution to the therapeutic planning of patients with complex hepatic vascularization