Optimal control of magnetization dynamics in ferromagnetic heterostructures by spin--polarized currents

We study the switching-process of the magnetization in a ferromagnetic-normal-metal multilayer system by a spin polarized electrical current via the spin transfer torque. We use a spin drift-diffusion equation (SDDE) and the Landau-Lifshitz-Gilbert equation (LLGE) to capture the coupled dynamics of the spin density and the magnetization dynamic of the heterostructure. Deriving a fully analytic solution of the stationary SDDE we obtain an accurate, robust, and fast self-consistent model for the spin-distribution and spin transfer torque inside general ferromagnetic/normal metal heterostructures. Using optimal control theory we explore the switching and back-switching process of the analyzer magnetization in a seven-layer system. Starting from a Gaussian, we identify a unified current pulse profile which accomplishes both processes within a specified switching time.Comment: 5 figure

Precision Measurement of the 29Si, 33S, and 36Cl Binding Energies

The binding energies of 29Si, 33S, and 36Cl have been measured with a relative uncertainty $< 0.59 \times 10^{-6}$ using a flat-crystal spectrometer. The unique features of these measurements are 1) nearly perfect crystals whose lattice spacing is known in meters, 2) a highly precise angle scale that is derived from first principles, and 3) a gamma-ray measurement facility that is coupled to a high flux reactor with near-core source capability. The binding energy is obtained by measuring all gamma-rays in a cascade scheme connecting the capture and ground states. The measurements require the extension of precision flat-crystal diffraction techniques to the 5 to 6 MeV energy region, a significant precision measurement challenge. The binding energies determined from these gamma-ray measurements are consistent with recent highly accurate atomic mass measurements within a relative uncertainty of $4.3 \times 10^{-7}$. The gamma-ray measurement uncertainties are the dominant contributors to the uncertainty of this consistency test. The measured gamma-ray energies are in agreement with earlier precision gamma-ray measurements.Comment: 13 pages, 4 figure

The Portuguese S3-Non-invasive Ventilation (S3-NIV) questionnaire for home mechanically ventilated patients

Short, valid and easy to use tools are needed to monitor home mechanical ventilation (HMV) in clinical practice and for organization of HMV services. The S3NIV is a self-administered questionnaire containing 11 items that includes a Respiratory Symptoms and Sleep & Side Effects subscores, ranging from 0 (highest impact of disease and treatment) to 10 (lowest impact of disease and treatment). The Portuguese version of the questionnaire was obtained using translation-back translation process with two professional translators and it was then validated on 234 stable patients (128 male patients, 53.8%) with a mean age of 69.3 (SD 11.0) years under long-term home non-invasive ventilation. Data on total score and subscales according to disease category are reported on the table. Internal consistency for the total score was good (Cronbach’s α coefficient of 0.76) as well as for the Respiratory Symptoms and the Sleep & Side effects domains (Cronbach’s α coefficient=0.68 and Cronbach’s α coefficient=0.72, respectively). The Portuguese version of the S3-NIV questionnaire is a simple and valid tool for the routine clinical assessment of patients receiving HMV. Although they have advanced diseases, it appears patients recognize treatment benefits and have controlled side effects

Thermodynamically Stable One-Component Metallic Quasicrystals

Classical density-functional theory is employed to study finite-temperature trends in the relative stabilities of one-component quasicrystals interacting via effective metallic pair potentials derived from pseudopotential theory. Comparing the free energies of several periodic crystals and rational approximant models of quasicrystals over a range of pseudopotential parameters, thermodynamically stable quasicrystals are predicted for parameters approaching the limits of mechanical stability of the crystalline structures. The results support and significantly extend conclusions of previous ground-state lattice-sum studies.Comment: REVTeX, 13 pages + 2 figures, to appear, Europhys. Let