Origin of Magnetism in a Supposedly Nonmagnetic Osmium Oxide.

A supposedly nonmagnetic 5d^{1} double perovskite oxide is investigated by a combination of spectroscopic and theoretical methods, namely, resonant inelastic x-ray scattering, x-ray absorption spectroscopy, magnetic circular dichroism, and multiplet ligand-field calculations. We found that the large spin-orbit coupling admixes the 5d t_{2g} and e_{g} orbitals, covalency raises the 5d population well above the nominal value, and the local symmetry is lower than O_{h}. The obtained electronic interactions account for the finite magnetic moment of Os in this compound and, in general, of 5d^{1} ions. Our results provide direct evidence of elusive Jahn-Teller distortions, hinting at a strong electron-lattice coupling.

Strain control of a bandwidth-driven spin reorientation in Ca3Ru2O7.

The layered-ruthenate family of materials possess an intricate interplay of structural, electronic and magnetic degrees of freedom that yields a plethora of delicately balanced ground states. This is exemplified by Ca3Ru2O7, which hosts a coupled transition in which the lattice parameters jump, the Fermi surface partially gaps and the spins undergo a 90∘ in-plane reorientation. Here, we show how the transition is driven by a lattice strain that tunes the electronic bandwidth. We apply uniaxial stress to single crystals of Ca3Ru2O7, using neutron and resonant x-ray scattering to simultaneously probe the structural and magnetic responses. These measurements demonstrate that the transition can be driven by externally induced strain, stimulating the development of a theoretical model in which an internal strain is generated self-consistently to lower the electronic energy. We understand the strain to act by modifying tilts and rotations of the RuO6 octahedra, which directly influences the nearest-neighbour hopping. Our results offer a blueprint for uncovering the driving force behind coupled phase transitions, as well as a route to controlling them.

Development of cadaver perfusion models for surgical training: an experimental study.

PURPOSE: Perfusion techniques on cadavers are heterogeneous and imperfect. The objective of this study was to improve the existing circulation model for surgical simulation on cadavers. METHODS: We used a three-step experimental approach. The first part of the experiment tested two variables: the type of circuit and the use of a heater for perfusion. The second approach evaluated two parameters: the injection fluid and the type of body conditioning (embalmed or freshly dead prepared using different washing techniques). The third one was an improvement on the best circulation obtained, which focused on the injection fluid. To compare the realism of these different techniques, we constructed a score with realism parameters: the volume of return flow, the presence of peripheral venous return and the perfusion of abdominal arteries. RESULTS: We found that the use of a heater seemed to improve the perfusion, while performing an arteriovenous bypass did not seem very effective. A correlation rate of 0.84 was found between the realism score and the injected fluid chosen. The best score (4/6) was found for a non-embalmed body with a low-pressure washing technique using a gelatin-based liquid at a concentration of 4 g/L for circulation. Scores obtained using embalmed bodies for both injection fluids for high-pressure washing or for 8-g/L gelatin injection fluid did not exceed 3/6. CONCLUSIONS: We showed that using a non-embalmed body with low-pressure washing and a 4-g/L gelatin-based fluid was the most effective technique for cadaver perfusion.