Echokardiographie zur verbesserten Risikostratifizierung vor aortokoronarer Bypass- Operation

Ziel war es, die prognostische Bedeutung neuer echokardiographischer Parameter vor aortokoronarer Myokardrevaskularisation zu überprüfen und mit der Bedeutung traditioneller Indices zu vergleichen. Es wurden 65 Patienten echokardiographisch untersucht und über 30 Tage verfolgt. 11 Patienten erlitten perioperativ ein kardiales Ereignis. Hiervon verstarben 4 Patienten wegen kardialer Ursache, 7 Patienten erlitten einen Myokardinfarkt. In der Cox-Regression waren ein erhöhter Tei-Index, eine vorangegangene Myokardrevaskularisation, das spätdiastolische Geschwindigkeitsmaximum und ein erhöhtes frühdiastolisches Geschwindigkeitsmaximum der Mitralringexkursion mit dem Endpunkt assoziiert. In der multivariaten Analyse waren eine vorangegangene Operation und ein erhöhter Tei-Index unabhängige Ereignisprädiktoren. Die ROC-Analyse ergab einen Trennwert von 0,69 für den Tei-Index. Bei Patienten mit Index größer 0,69 war ein Ereignis signifikant häufiger als bei Patienten mit Index kleiner 0,69

A Magnetic Transition Probed by the Ce Ion in Square-Lattice Antiferromagnet CeMnAsO

We examined the magnetic properties of the square-lattice antiferromagnets CeMnAsO and LaMnAsO and their solid solutions La1-xCexMnAsO by resistivity, magnetic susceptibility, and heat capacity measurements below room temperature. A first-order phase transition is observed at 34.1 K, below which the ground-state doublet of the Ce ion splits by 3.53 meV. It is likely that Mn moments already ordered above room temperature are reoriented at the transition, as reported for related compounds, such as NdMnAsO and PrMnSbO. This transition generates a large internal magnetic field at the Ce site in spite of the fact that simple Heisenberg interactions should be cancelled out at the Ce site owing to geometrical frustration. The transition takes place at nearly the same temperature with the substitution of La for Ce up to 90%. The Ce moment does not undergo long-range order by itself, but is parasitically induced at the transition, serving as a good probe for detecting the magnetism of Mn spins in a square lattice.Comment: 11 pages, 5 figures, to be published in J. Phys. Soc. Jp

Electronic structure and Fermi surface character of LaONiP from first principles

Based on First-principles calculation, we have investigated electronic structure of a ZrCuSiAs structured superconductor LaNiPO. The density of states, band structures and Fermi surfaces have been given in detail. Our results indicate that the bonding of the La-O and Ni-P is strongly covalent whereas binding property between the LaO and NiP blocks is mostly ionic. It's also found that four bands are across the Fermi level and the corresponding Fermi surfaces all have a two-dimensional character. In addition, we also give the band decomposed charge density, which suggests that orbital components of Fermi surfaces are more complicated than cuprate superconductors.Comment: Submitted to Phys.Rev.

Spectroscopic Study of 75^{75}As and 139^{139}La NMR on Layered Structure Ferromagnet LaCoAsO

$^{75}$As and $^{139}$La field-swept NMR spectra were obtained for the novel weakly itinerant ferromagnet LaCoAsO with 2D layered structure above the Curie temperature of 55 K. By analyzing NMR spectra, temperature dependences of Knight shift $K$ and nuclear quadrupole resonance frequency $\nu_Q$ were obtained successfully for each nucleus. We confirmed from the so-called $K$-$\chi$ plots that the macroscopic magnetization of our {LaCoAsO} powder sample is intrinsic and does not contain the contribution from impurity phases. We estimated hyperfine coupling constants from the slope of $K$-$\chi$ plots and compared to that of iron-arsenide superconductor.Comment: 5 pages, 5 figures, published on J. Phys. Soc. Jpn. at Vol.79, pp.054703 (2010)

Electronic structure of new quaternary superconductors LaONiBi and LaOCuBi from first principles

Based on first-principles FLAPW-GGA calculations, we have investigated the electronic structure of newly synthesized novel superconductors LaONiBi and LaOCuBi, the first bismuth-containing compounds from the family of quaternary oxypnictides which attract now a great deal of interest in search for novel 26-55K superconductors. The band structure, density of states and Fermi surfaces are discussed. Our results indicate that the bonding inside of the (La-O) and (Ni(Cu)-Bi) layers is covalent whereas the bonding between the (La-O) and (Ni(Cu)- Bi) blocks is mostly ionic. For both oxybismuthides, the DOSs at the Fermi level are formed mainly by the states of the (Ni(Cu)-Bi) layers, the corresponding Fermi surfaces have a twodimensional character and the conduction should be strongly anisotropic andhappen only on the (Ni(Cu)-Bi) layers. As a whole, the new oxybismuthides may be described as low-TC superconducting non-magnetic ionic metals.Comment: 13 pages, 5 figure

Crystallographic Phase Transition and High-Tc Superconductivity in LaFeAsO:F

Undoped LaFeAsO, parent compound of the newly found high-Tc superconductor, exhibits a sharp decrease in the temperature-dependent resistivity at ~160 K. The anomaly can be suppressed by F doping and the superconductivity appears correspondingly, suggesting a close associate of the anomaly with the superconductivity. We examined the crystal structures, magnetic properties and superconductivity of undoped (normal conductor) and 14 at.% F-doped LaFeAsO (Tc = 20 K) by synchrotron X-ray diffraction, DC magnetic measurements, and ab initio calculations to demonstrate that the anomaly is associated with a phase transition from tetragonal (P4/nmm) to orthorhombic (Cmma) phases at ~160 K as well as an antiferromagnetic transition at ~140 K. These transitions can be explained by spin configuration-dependent potential energy surfaces derived from the ab initio calculations. The suppression of the transitions is ascribed to interrelated effects of geometric and electronic structural changes due to doping by F- ions.Comment: 22 pages, 8 figures, 2 tables, Supplementary information is included at the end of the document, accepted for publication in Supercond. Sci. Techno

Chemistry of layered d-metal pnictide oxides and their potential as candidates for new superconductors

Layered d-metal pnictide oxides are a unique class of compounds which consists of characteristic d-metal pnictide layers and metal oxide layers. More than 100 of these layered compounds, including the recently discovered Fe-based superconducting pnictide oxides, can be classified into 9 structure types. These structure types and the chemical and physical properties of the characteristic d-metal pnictide layers and metal oxide layers of the layered d-metal pnictide oxides are reviewed and discussed. Furthermore, possible approaches to design new superconductors based on these layered d-metal pnictide oxides are proposed.Comment: 29 pages including 6 tables and 2 figure

Kulturen des Entscheidens

Der Band thematisiert Entscheiden als eine soziale Praxis, die keineswegs selbstverständlich sondern in hohem Maße voraussetzungsvoll ist und die mit unterschiedlichen Zumutungen einhergeht. Entscheiden nimmt je nach sozialen Umständen ganz unterschiedliche Formen an und unterliegt demnach dem historischen Wandel. Die Beiträge des Bandes gehen anhand ausgewählter Fallbeispiele, die vom mittelalterlichen Europa bis hin zum gegenwärtigen Indien reichen, unterschiedlichen Aspekten von Kulturen des Entscheidens nach. Sie nehmen Narrative und Praktiken des Entscheidens ebenso in den Blick wie den Einsatz von Ressourcen in Prozessen des Entscheidens und diskutieren Ansätze, Entscheiden in einer geistes- und kulturwissenschaftlichen Perspektive zu analysieren. Der Band zeigt so die vielfältigen Möglichkeiten auf, wie Entscheiden untersucht werden kann, wenn dieses als eine historisch wandelbare soziale Praxis und als kulturell diverses Phänomen begriffen wird