113 research outputs found
Correlation between Tc and Lattice Parameters of Novel Superconducting NaxCoO2 yH2O
We synthesized the five batches of the samples of the novel P3 type
superconductor, Na(HO)CoOHO, by the
soft chemical process starting from -NaCoO. The chemical and
structural properties varied rather widely from batch to batch, with a result
that varied from 4.6 K to 3.2 K. The magnetic susceptibility above
shows upturn at low temperature as in the case of the P2 phase. The
seems to be well correlated to the lattice parameters.Comment: 2 pages, 2 figures, and 1 table, to be published in J. Phys. Soc.
Jpn. 73 (9) with possible minor revision
Novel Fourier-domain constraint for fast phase retrieval in coherent diffraction imaging
Coherent diffraction imaging (CDI) for visualizing objects at atomic
resolution has been realized as a promising tool for imaging single molecules.
Drawbacks of CDI are associated with the difficulty of the numerical phase
retrieval from experimental diffraction patterns; a fact which stimulated
search for better numerical methods and alternative experimental techniques.
Common phase retrieval methods are based on iterative procedures which
propagate the complex-valued wave between object and detector plane.
Constraints in both, the object and the detector plane are applied. While the
constraint in the detector plane employed in most phase retrieval methods
requires the amplitude of the complex wave to be equal to the squared root of
the measured intensity, we propose a novel Fourier-domain constraint, based on
an analogy to holography. Our method allows achieving a low-resolution
reconstruction already in the first step followed by a high-resolution
reconstruction after further steps. In comparison to conventional schemes this
Fourier-domain constraint results in a fast and reliable convergence of the
iterative reconstruction process.Comment: 13 pages, 7 figure
Biomolecular imaging and electronic damage using X-ray free-electron lasers
Proposals to determine biomolecular structures from diffraction experiments
using femtosecond X-ray free-electron laser (XFEL) pulses involve a conflict
between the incident brightness required to achieve diffraction-limited atomic
resolution and the electronic and structural damage induced by the
illumination. Here we show that previous estimates of the conditions under
which biomolecular structures may be obtained in this manner are unduly
restrictive, because they are based on a coherent diffraction model that is not
appropriate to the proposed interaction conditions. A more detailed imaging
model derived from optical coherence theory and quantum electrodynamics is
shown to be far more tolerant of electronic damage. The nuclear density is
employed as the principal descriptor of molecular structure. The foundations of
the approach may also be used to characterize electrodynamical processes by
performing scattering experiments on complex molecules of known structure.Comment: 16 pages, 2 figure
Imperfection and radiation damage in protein crystals studied with coherent radiation
Fringes and speckles occur within diffraction spots when a crystal is illuminated with coherent radiation during X-ray diffraction. The additional information in these features provides insight into the imperfections in the crystal at the sub-micrometre scale. In addition, these features can provide more accurate intensity measurements (e.g. by model-based profile fitting), detwinning (by distinguishing the various components), phasing (by exploiting sampling of the molecular transform) and refinement (by distinguishing regions with different unit-cell parameters). In order to exploit these potential benefits, the features due to coherent diffraction have to be recorded and any change due to radiation damage properly modelled. Initial results from recording coherent diffraction at cryotemperatures from polyhedrin crystals of approximately 2 µm in size are described. These measurements allowed information about the type of crystal imperfections to be obtained at the sub-micrometre level, together with the changes due to radiation damage
PERSPECTIVAS DEL PROCESO DE GLOBALIZACIÓN Y SU INFLUENCIA SOBRE LOS DERECHOS HUMANOS ECONÓMICOS, SOCIALES Y CULTURALES
El escenario internacional se encuentra en constante transformación debido a lo que se ha denominado el proceso de “globalización”. Este afecta las relaciones internaciones interestatales e influye en la vida cotidiana de los individuos. El Derecho Internacional y más específicamente el Derecho Internacional de los Derechos Humanos no es ajeno a este proceso. La investigación afirma que nos encontramos frente a una etapa de transnacionalización de los Derechos Humanos, que permite que los individuos cuenten con mayor protección en ámbitos supranacionales. También hace especial mención a los derechos Económicos Sociales y Culturales, analiza el debate sobre el pluralismo jurídico y la eficacia diferencial. En la metodología empleada se revisan fuentes documentales y se realiza un análisis de algunos derechos particulares previstos en el Pacto de Derechos Económicos, Sociales y Culturales. Los planteamientos permiten afirmar que el proceso de globalización ha determinado la transnacionalización de los Derechos Humanos, surgiendo de dicho fenómeno consecuencias positivas y negativas en cuanto a su cumplimiento
Panel 6: Aftermath and Memory of the Armenian Genocide
Panel 6: Aftermath and Memory of the Armenian Genocide
David Okonyan, Claremont Graduate University: “The Consequences of Denial: Interpreting the History of the Armenian Genocide Memorial in Montebello, California” Download paper (login required)
Karina Dilanian-Pinkowicz, Polish Academy of Sciences, Poland: “The Post-1960s Revival of Official Memory of the Armenian Genocide Download paper (login required)
Talin Suciyan, Ludwig Maximilians University, Germany: “Armenians in Istanbul between 1945 and 1950” Download paper (login required)
Chair: Ümit Kurt and Raz Segal, Clark UniversityComment: Taner Akçam, Clark Universit
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