Magnetization dynamics in microscopic spin-valve elements: Shortcomings of the macrospin picture

We have studied ultrafast magnetodynamics in micropatterned spin-valve structures using time-resolved x-ray photoemission electron microscopy combined with x-ray magnetic circular dichroism. Exciting the system with ultrafast field pulses of 250 ps width, we find the dynamic response of the free layer to fall into two distinctly different contributions. On the one hand, it exhibits localized spin wave modes that strongly depend on the shape of the micropattern. A field pulse applied perpendicular to the exchange bias field along the diagonal of a square pattern leads to the excitation of a standing spin wave mode with two nodes along the field direction. This mode is strongly suppressed for a pattern of elliptical shape. On the other hand, the integrated response of the free layer roughly follows a single-spin model with a damping constant of alpha=0.025 independent of the shape and resembles the response of a critically damped forced oscillator

Managing housing needs in post conflict housing reconstruction in Sri Lanka: gaps versus recommendations

Addressing housing needs in post conflict housing reconstruction leads to successful housing reconstruction. As part of a study of investigating how the housing needs can be effectively addressed in post conflict housing reconstruction, this paper identifies the gaps in managing housing needs in post conflict housing reconstruction within the context of Sri Lanka and presents the recommendations to minimise such gaps. Data was collected through un-structured interviews conducted with 37 participants, comprising policy makers, practitioners, academics and beneficiaries who engaged in post conflict housing reconstruction in Sri Lanka. Gaps were mainly found in conflict sensitivity, measures related to physical housing, performance of implementing agencies, policy and practice issues. On the job training, application of ‘do no harm’ principles, enhanced beneficiary participation, enhanced accountability, effective monitoring, enhanced knowledge sharing, adequate drinking water facilities, irrigation development and initiatives for material manufacturing were suggested as recommendations to minimise these gaps. Identification of gaps in managing housing needs in post conflict housing reconstruction and recommendations to minimise them inform policy makers to address the housing needs effectively through incorporating these aspects into the related policies. This in turn enhances the sustainability in housing development after conflicts

Sparse canonical correlation analysis for identifying, connecting and completing gene-expression networks

<p>Abstract</p> <p>Background</p> <p>We generalized penalized canonical correlation analysis for analyzing microarray gene-expression measurements for checking completeness of known metabolic pathways and identifying candidate genes for incorporation in the pathway. We used Wold's method for calculation of the canonical variates, and we applied ridge penalization to the regression of pathway genes on canonical variates of the non-pathway genes, and the elastic net to the regression of non-pathway genes on the canonical variates of the pathway genes.</p> <p>Results</p> <p>We performed a small simulation to illustrate the model's capability to identify new candidate genes to incorporate in the pathway: in our simulations it appeared that a gene was correctly identified if the correlation with the pathway genes was 0.3 or more. We applied the methods to a gene-expression microarray data set of 12, 209 genes measured in 45 patients with glioblastoma, and we considered genes to incorporate in the glioma-pathway: we identified more than 25 genes that correlated > 0.9 with canonical variates of the pathway genes.</p> <p>Conclusion</p> <p>We concluded that penalized canonical correlation analysis is a powerful tool to identify candidate genes in pathway analysis.</p

Self-trapping of magnetic oscillation modes in Landau flux-closure structures

We investigated the magnetodynamics in rectangular Permalloy platelets by means of time-resolved x-ray photoemission microscopy. 10 nm thick platelets of 16x32 mu m size were excited by an oscillatory field along the short side of the sample with a fundamental frequency of 500 MHz and considerable contributions of higher harmonics. Under the influence of the oscillatory field, the Neel wall in the initial classical Landau pattern shifts away from the center, corresponding to an induced magnetic moment perpendicular to the exciting field. This phenomenon is explained by a self-trapping effect of the dominating spin-wave mode when the system is excited just below the resonance frequency. The basic driving mechanism is the maximization of entropy