Intraoperative Ultrasonography Evaluation of the Gallbladder in Morbidly Obese Patients

Intraoperative ultrasound evaluation of the gallbladder was performed in 55 morbidly obese patients undergoing gastric bariatric surgery. Cholecystectomy was performed in the presence of any physical or ultrasonographic abnormality. Eighteen patients (33%) had cholecystectomy. Nine patients had palpable gallbladder disease confirmed by ultrasound. Nine patients had abnormalities detected by ultrasonography only. There was no false-negative ultrasonographic exam compared to physical exam. Pathologically, all specimens but one showed evidence of disease, thus there was a false-positive incidence of 1.8%. None of the 37 patients with normal physical and ultrasonographic examination have returned with gallbladder disease following the bariatric surgery. Intraoperative ultrasonography shows promise in detecting nonpalpable gallbladder disease and decreasing the incidence of delayed cholecystectomy

Symmetry Control of Unconventional Spin–Orbit Torques in IrO\u3csub\u3e2\u3c/sub\u3e

Spin–orbit torques generated by a spin current are key to magnetic switching in spintronic applications. The polarization of the spin current dictates the direction of switching required for energy-efficient devices. Conventionally, the polarizations of these spin currents are restricted to be along a certain direction due to the symmetry of the material allowing only for efficient in-plane magnetic switching. Unconventional spin–orbit torques arising from novel spin current polarizations, however, have the potential to switch other magnetization orientations such as perpendicular magnetic anisotropy, which is desired for higher density spintronic-based memory devices. Here, it is demonstrated that low crystalline symmetry is not required for unconventional spin–orbit torques and can be generated in a nonmagnetic high symmetry material, iridium dioxide (IrO2), using epitaxial design. It is shown that by reducing the relative crystalline symmetry with respect to the growth direction large unconventional spin currents can be generated and hence spin–orbit torques. Furthermore, the spin polarizations detected in (001), (110), and (111) oriented IrO2 thin films are compared to show which crystal symmetries restrict unconventional spin transport. Understanding and tuning unconventional spin transport generation in high symmetry materials can provide a new route towards energy-efficient magnetic switching in spintronic devices

GENERATION OF SPIN CURRENTS IN FERROMAGNETIC MATERIALS

147 pagesThis thesis will discuss the utilization of ferromagnets for the generation of spin currents via various spin Hall like effects. The global magnetic order in a ferromagnetic material breaks the requisite symmetries to allow for the generation of spin currents with arbitrary polarizations which could prove useful for magnetic information storage technology. We first discuss some of the theoretical background of the various microscopic origins which can lead to spin Hall currents in ferromagnets as well as the theory behind some of the the experimental techniques used in this thesis. We then describe the measurement of a non-reorientable component of the spin Hall effect generated by a ferromagnetic Ni-Fe alloy using the spin torque ferromagnetic resonance technique, as well as modifications that we needed to make to the analysis of these measurements to account for coupling between magnetic layers driven by dynamic spin pumping. We conclude with a discussion of the materials problems which must be solved to utilize the spin anomalous Hall effect to switch out-of-plane polarized ferromagnetic layers as well as our attempts to realize such material systems.2023-03-0

Novel Spin-Orbit Torque Generation at Room Temperature in an All-Oxide Epitaxial La0.7 Sr0.3 MnO3 /SrIrO3 System.

Spin-orbit torques (SOTs) that arise from materials with large spin-orbit coupling offer a new pathway for energy-efficient and fast magnetic information storage. SOTs in conventional heavy metals and topological insulators are explored extensively, while 5d transition metal oxides, which also host ions with strong spin-orbit coupling, are a relatively new territory in the field of spintronics. An all-oxide, SrTiO3 (STO)//La0.7 Sr0.3 MnO3 (LSMO)/SrIrO3 (SIO) heterostructure with lattice-matched crystal structure is synthesized, exhibiting an epitaxial and atomically sharp interface between the ferromagnetic LSMO and the high spin-orbit-coupled metal SIO. Spin-torque ferromagnetic resonance (ST-FMR) is used to probe the effective magnetization and the SOT efficiency in LSMO/SIO heterostructures grown on STO substrates. Remarkably, epitaxial LSMO/SIO exhibits a large SOT efficiency, ξ||  = 1, while retaining a reasonably low shunting factor and increasing the effective magnetization of LSMO by ≈50%. The findings highlight the significance of epitaxy as a powerful tool to achieve a high SOT efficiency, explore the rich physics at the epitaxial interface, and open up a new pathway for designing next-generation energy-efficient spintronic devices

Do patients with traumatic brain injury learn a route in the same way in real and virtual environments?

International audienceUNLABELLED: An increasing number of studies address the use of virtual environments (VE) in the cognitive assessment of spatial abilities. However, the differences between learning in a VE and a real environment (RE) remain controversial. PURPOSE: To compare the topographical behavior and spatial representations of patients with traumatic brain injury navigating in a real environment and in a virtual reproduction of this environment. METHODS: Twenty-seven subjects with moderate to severe traumatic brain injury were consecutively included and allocated to one of two groups. The subjects were taught the same route in either the virtual environment or the real environment and had to recall it twice immediately after learning the route and once after a delay. At the end of these sessions, the subjects were asked to complete three representational tests: a map test, a map recognition test recognition and a scene arrangement test. RESULTS: No significant difference was found between the two groups with regards to demographics, severity of brain injury or episodic memory. As a main result, the number of error rates did not significantly differ between the real and virtual environment [F (1, 25) = 0.679; p = 0.4176)]. Scores on the scene arrangement test were higher in the real environment [U = 32.5; p = 0.01]. CONCLUSIONS: Although spatial representations probably differ between the real and virtual environment, virtual reality remains a trusty assessment tool for spatial abilities