Spin-transfer-driven nano-oscillators are equivalent to parametric resonators

The equivalence between different physical systems permits us to transfer knowledge between them and to characterize the universal nature of their dynamics. We demonstrate that a nanopillar driven by a spin-transfer torque is equivalent to a rotating magnetic plate, which permits us to consider the nanopillar as a macroscopic system under a time-modulated injection of energy, that is, a simple parametric resonator. This equivalence allows us to characterize the phases diagram and to predict magnetic states and dynamical behaviors, such as solitons, stationary textures, and oscillatory localized states, among others. Numerical simulations confirm these predictions.Comment: 8 pages, 7 figure

JOB BURNOUT AND PERFORMANCE OF STAFF NURSES IN SELECTED HOSPITALS IN METRO MANILA

This study was conducted to determine the job burnout and performance of staff nurses in selected tertiary hospitals in Manila using the Oldenburg Burnout Inventory. Results showed that there’s: a high degree of agreement in relation to burnout of the staff-nurses in terms of exhaustion and disengagement; an average level of performance of the staff nurses in terms of task performance, contextual performance, and counter-productive behavior; significant differences between the degrees of agreement in relation to job burnout of the staff-nurses (disengagement and exhaustion) when they are grouped according to nurse-patient ratio and census per area; significant relationships between the degree of agreement in relation to job burnout (disengagement) and overall level of performance of the staff nurses. Researchers pursued this study because some of their colleagues have lost the enjoyment of their job; that they feel that their efforts were being unnoticed; and feel overworked. Through this study, the degree of agreement in relation to job burnout of the staff nurses and their level of performance was determined. This paved a way for the development of new plans and programs to help staff nurses overcome their feelings of burnout, making them more energetic and enthusiastic in performing their job

A Survey of Proper Motion Stars. XVII. A Deficiency of Binary Stars on Retrograde Galactic Orbits and the Possibility that omega Centauri is Related to the Effect

We find a deficiency of binary stars moving on strongly retrograde Galactic orbits. No binary deficiencies are seen for U or W velocities, however. From theoretical analyses, we rule out preferential disruption of pre-existing binary stars due to encounters with massive perturbers. We also rule out globular clusters as the source of the effect since prograde motions are more likely to create such an effect. We search for star streams and find one possible candidate, but it is not on a retrograde orbit and probably represents the remains of a cluster that has passed too near the Galactic center. Based on a very small number of stars, we find that about the right fraction of stars on retrograde Galactic orbits share some chemical similarities to the cluster omega Cen, suggesting that its parent galaxy could be the explanation.Comment: To appear in the Astronomical Journal (March 2005 issue

On the Equivalence Between Type I Liouville Dynamical Systems in the Plane and the Sphere

Producción CientíficaSeparable Hamiltonian systems either in sphero-conical coordinates on an S2 sphere or in elliptic coordinates on a R2 plane are described in a unified way. A back and forth route connecting these Liouville Type I separable systems is unveiled. It is shown how the gnomonic projection and its inverse map allow us to pass from a Liouville Type I separable system with a spherical configuration space to its Liouville Type I partners where the configuration space is a plane and back. Several selected spherical separable systems and their planar cousins are discussed in a classical context

Low-energy Compton scattering on the nucleon and sum rules

The Gerasimov-Drell-Hearn and Baldin-Lapidus sum rules are evaluated in the dressed K-matrix model for photon-induced reactions on the nucleon. For the first time the sum $\alpha+\beta$ of the electric and magnetic polarisabilities and the forward spin polarisability $\gamma_0$ are explicitly calculated in two alternative ways -- from the sum rules and from the low-energy expansion of the real Compton scattering amplitude -- within the {\em same} framework. The two methods yield compatible values for $\alpha+\beta$ but differ somewhat for $\gamma_0$. Consistency between the two ways of determining the polarisabilities is a measure of the extent to which basic symmetries of the model are obeyed.Comment: 9 pages, 4 figures, using REVTeX. More concise version, results unchanged. To appear in Phys. Rev.