1,720,994 research outputs found
X-ray Absorption Studies on the N-terminal Copper-binding Region of Haemophilus ducreyi Cu,Zn Superoxide Dismutase
No full textQuantitative analysis of x-ray absorption near edge structure data by a full multiple scattering procedure: the Fe-CO geometry in photolysed carbonmonoxy-myoglobin single crystal
No full textLight-Induced Relaxation of Photolyzed Carbonmonoxy Myoglobin: A Temperature-Dependent X-Ray Absorption Near-Edge Structure (XANES) Study
No full textX-ray absorption near-edge structure (XANES) spectra at the Fe K-edge have been measured and compared on
solution samples of horse carbonmonoxy-myoglobin and its photoproducts, prepared by two different photolysis protocols: 1),
extended illumination at low temperature (15 K) by white light; and 2), slow-cool from 140 to 10 K at a rate of 0.5 K/min while
illuminating the sample with a 532-nm continuous-wave laser source. CO recombination has been followed while increasing the
temperature at a rate of 1.2 K/min. After extended illumination at 15 K, a single process is observed, corresponding to CO
recombination from a completely photolyzed species with CO bound to the primary docking site (formally B-state, in agreement
with previous x-ray diffraction studies). The temperature peak for this single process is ;50 K. Using slow-cool illumination, data
show a two-state recombination curve, the two temperature peaks being roughly assigned to 50 K and 110 K. These results are
in good agreement with previous FTIR studies using temperature-derivative spectroscopy. The XANES spectroscopic markers
probe structural differences between the photoproduct induced by extended illumination at 15 K and the photoproduct induced
by slow-cool illumination. These differences in the XANES data have been interpreted as due to light-induced Fe-heme
relaxation that does not involve CO migration from the B-state. A quantitative description of the unrelaxed and relaxed B-states,
including the measurements of the Fe-Np, Fe-NHis, and Fe-CO distances, and the out-of-plane Fe displacement, has been
obtained via a procedure (MXAN) recently developed by us. This work shows that XANES, being able to extract both kinetic and
structural parameters in a single experiment, is a powerful tool for structural dynamic studies of protein
structural Origin of magnetic perpendicular anisotropy in Co-Pt alloy films probed by polarized XAFS
No full textXAFS measurements on Co-K and Pt -L(III) edges in (111) CoPt3 films
No full textXAFS measurements at the Co-K edge and Pt-LIII edge were performed in an (111) epitaxial CoPt3 film with strong perpendicular magnetic anisotropy. The analysis of XAFS data obtained using in-plane and out-of-plane polarization show the existence of an anisotropic local order characterized by preferential heteroatomic pairs out of the film plane balanced with preferential homoatomic pairs in the (111) plane. The isotropic local order found in a magnetically isotropic CoPt3 film from Pt-LIII edge data should be confirmed by XAFS measurements on Co-edge
Temperature dependent modulation amplitude of the CuO2 superconducting plane in La2CuO4.1
No full textThe temperature-dependent amplitude of the Cu-O(planar) bond modulation in the La2CuO4.1 superconducting crystal has been measured by in-plane-polarized Cu K-edge extended x-ray-absorption Pine structure. Minority domains characterized by a long Cu-O(planar) bond length are found at T < 150 K. The separation between the two Cu-O(planar) distances provides a measure of the amplitude of the CuO2 lattice modulation assigned to a charge-density wave that coexists with the superconducting phase, providing evidence for a broken symmetry
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Non-homogeneity of the CuO2 plane of the oxygen doped La2CuO4.1 system by polarized EXAFS
No full textTemperature dependent in-plane polarized Cu K-edge extended x-ray absorption fine structure (EXAFS) study has been carried out on a high quality single crystal of oxygen doped La2CuO4.1 (LCO) system to investigate the local structure around Cu. The EXAFS data recorded with high degree of plane polarization and up to high momentum transfer (Q=40 A(-1) = 2k) allowed the quantitative determination of the distorted and undistorted Cu planes. The determination of the Cu-O(planar) distances shows presence of minority Cu sites characterized by two longer Cu-O(planar) bonds and a tilting of 15 degrees with the average crystallographic structure at T < T-s similar to 150 K. The data show the coexistence of localized and itinerant charges trapped into stripes of distorted and undistorted domains within the CuO2 plane
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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