Investigation of the thermal stability of Mg/Co periodic multilayers for EUV applications

We present the results of the characterization of Mg/Co periodic multilayers and their thermal stability for the EUV range. The annealing study is performed up to a temperature of 400\degree C. Images obtained by scanning transmission electron microscopy and electron energy loss spectroscopy clearly show the good quality of the multilayer structure. The measurements of the EUV reflectivity around 25 nm (~49 eV) indicate that the reflectivity decreases when the annealing temperature increases above 300\degreeC. X-ray emission spectroscopy is performed to determine the chemical state of the Mg atoms within the Mg/Co multilayer. Nuclear magnetic resonance used to determine the chemical state of the Co atoms and scanning electron microscopy images of cross sections of the Mg/Co multilayers reveal changes in the morphology of the stack from an annealing temperature of 305\degreee;C. This explains the observed reflectivity loss.Comment: Published in Applied Physics A: Materials Science \& Processing Published at http://www.springerlink.com.chimie.gate.inist.fr/content/6v396j6m56771r61/ 21 page

White matter damage and cognitive impairment after traumatic brain injury

White matter disruption is an important determinant of cognitive impairment after brain injury, but conventional neuroimaging underestimates its extent. In contrast, diffusion tensor imaging provides a validated and sensitive way of identifying the impact of axonal injury. The relationship between cognitive impairment after traumatic brain injury and white matter damage is likely to be complex. We applied a flexible technique—tract-based spatial statistics—to explore whether damage to specific white matter tracts is associated with particular patterns of cognitive impairment. The commonly affected domains of memory, executive function and information processing speed were investigated in 28 patients in the post-acute / chronic phase following traumatic brain injury and in 26 age-matched controls. Analysis of fractional anisotropy and diffusivity maps revealed widespread differences in white matter integrity between the groups. Patients showed large areas of reduced fractional anisotropy, as well as increased mean and axial diffusivities, compared with controls, despite the small amounts of cortical and white matter damage visible on standard imaging. A stratified analysis based on the presence or absence of microbleeds (a marker of diffuse axonal injury) revealed diffusion tensor imaging to be more sensitive than gradient-echo imaging to white matter damage. The location of white matter abnormality predicted cognitive function to some extent. The structure of the fornices was correlated with associative learning and memory across both patient and control groups, whilst the structure of frontal lobe connections showed relationships with executive function that differed in the two groups. These results highlight the complexity of the relationships between white matter structure and cognition. Although widespread and, sometimes, chronic abnormalities of white matter are identifiable following traumatic brain injury, the impact of these changes on cognitive function is likely to depend on damage to key pathways that link nodes in the distributed brain networks supporting high-level cognitive functions

Bupropion for the treatment of apathy in Huntington's disease:A multicenter, randomised, double-blind, placebo-controlled, prospective crossover trial

OBJECTIVE:To evaluate the efficacy and safety of bupropion in the treatment of apathy in Huntington's disease (HD). METHODS:In this phase 2b multicentre, double-blind, placebo-controlled crossover trial, individuals with HD and clinical signs of apathy according to the Structured Clinical Interview for Apathy-Dementia (SCIA-D), but not depression (n = 40) were randomized to receive either bupropion 150/300mg or placebo daily for 10 weeks. The primary outcome parameter was a significant change of the Apathy Evaluation Scale (AES) score after ten weeks of treatment as judged by an informant (AES-I) living in close proximity with the study participant. The secondary outcome parameters included changes of 1. AES scores determined by the patient (AES-S) or the clinical investigator (AES-C), 2. psychiatric symptoms (NPI, HADS-SIS, UHDRS-Behavior), 3. cognitive performance (SDMT, Stroop, VFT, MMSE), 4. motor symptoms (UHDRS-Motor), 5. activities of daily function (TFC, UHDRS-Function), and 6. caregiver distress (NPI-D). In addition, we investigated the effect of bupropion on brain structure as well as brain responses and functional connectivity during reward processing in a gambling task using magnetic resonance imaging (MRI). RESULTS:At baseline, there were no significant treatment group differences in the clinical primary and secondary outcome parameters. At endpoint, there was no statistically significant difference between treatment groups for all clinical primary and secondary outcome variables. Study participation, irrespective of the intervention, lessened symptoms of apathy according to the informant and the clinical investigator. CONCLUSION:Bupropion does not alleviate apathy in HD. However, study participation/placebo effects were observed, which document the need for carefully controlled trials when investigating therapeutic interventions for the neuropsychiatric symptoms of HD. TRIAL REGISTRATION:ClinicalTrials.gov 01914965

SPECTRES X DE COMPOSÉS DU CUIVRE

Les spectres X d'émission et d'absorption L du cuivre dans Cu2O, CuCl et CuO ont été analysés et discutés comparativement ; des informations concernant les distributions d'états dans ces composés ont été déduites.The L emission and absorption X-ray spectra of copper in Cu2O, CuCl and CuO have been analysed and compared ; information concerning the distribution of the states in the compounds was deduced

Advances in X-ray spectroscopy: contributions in honour of professor Y. Cauchois

Advances in X-Ray Spectroscopy covers topics relevant to the advancement of X-ray spectroscopy technology. The book is a collection of papers written by specialists in X-ray spectroscopy and pays tribute to the scientific work of Prof. Yvette Cauchois. The text is organized into four parts. Part I covers the analysis of X-ray transitions between atomic levels and relativistic theories of X-ray emission satellites and electron BremsStrahlung. Part II reviews the means provided by X-ray spectroscopy for the determination of the electronic structure of solids, while Part III discusses methods o

DISTRIBUTIONS DES ÉTATS f DANS LES MÉTAUX ET LES OXYDES DE TERRES RARES

L'étude des transitions mettant en jeu des états à caractère f a permis de mettre en évidence, dans les spectres X, des raies d'un type nouveau, analogues aux raies de résonance des spectres optiques. Les émissions correspondant aux états f occupés ont été identifiées et leur intensité est discutée comparativement à celle des raies de résonance. Les distributions f occupées et inoccupées ainsi que leur position par rapport au niveau de Fermi du métal sont données dans quelques cas.The study of transitions involving f states has revealed, in X-ray spectra, the existance of lines of a new type, analogous to optical resonance lines. The emissions corresponding to occupied f states are identified and their intensities, compared with those of the resonance lines, are discussed. The occupied and inoccupied f distributions, and their positions with respect to the Fermi level in the metal are given in some cases

ELECTRONIC DISTRIBUTIONS OF UO2 BY X-RAY SPECTROSCOPY

A partir des spectres d'absorption et d'émission X et des résultats obtenus par photoémission X, nous proposons un diagramme des niveaux d'énergie pour UO2. Les caractéristiques des états 5f de l'uranium dans ce composé sont discutées. Nous observons à la fois des états 5f mélangés aux orbitales 2p de l'oxygène, qui traduisent un effet de covalence, et des états 5f purs localisés remplis ou vides et situés dans la bande interdite.From X-ray absorption and emission spectra and X-ray photoemission results, an energy level diagram is proposed for UO2. Emphasis is placed on the properties of the 5f states in this solid. A covalent mixing of uranium 5f and oxygen 2p orbitals is found. Pure localized uranium 5f levels are also present ; these are either filled or empty excitation levels situated in the band gap