Exploring nanomagnetism with soft x-ray microscopy

Magnetic soft X-ray microscopy images magnetism in nanoscale systems with a spatial resolution down to 15nm provided by state-of-the-art Fresnel zone plate optics. X-ray magnetic circular dichroism (X-MCD) is used as element-specific magnetic contrast mechanism similar to photoemission electron microscopy (PEEM), however, with volume sensitivity and the ability to record the images in varying applied magnetic fields which allows to study magnetization reversal processes at fundamental length scales. Utilizing a stroboscopic pump-probe scheme one can investigate fast spin dynamics with a time resolution down to 70 ps which gives access to precessional and relaxation phenomena as well as spin torque driven domain wall dynamics in nanoscale systems. Current developments in zone plate optics aim for a spatial resolution towards 10nm and at next generation X-ray sources a time resolution in the fsec regime can be envisioned

Survival analysis using Medicare data: example and methods.

OBJECTIVE: To describe key methods and issues in conducting survival analyses, especially using Medicare (and other) administrative data. PRINCIPAL FINDINGS: Survival analyses are rich , informative, and underutilized methods for examining out comes whose timing is important . Medicare files contain the necessary information for conducting such analyses, including identification of cohorts, definition of events, censoring of observations, and adjustment for covariates. CONCLUSION: Survival analyses can readily be conducted using the information contained in administrative data files

How much better can we predict dialysis patient survival using clinical data?

OBJECTIVE: To use three approaches to compare dialysis survival prediction based on variables included in the Standardized Mortality Ratio (SMR) with prediction based on a clinically enriched set of variables. DATA SOURCE: The United States Renal Data System Case Mix Severity data set containing demographic, clinical, functional, nutritional, and treatment details about a random sample of 4,797 adult dialysis patients from 291 treatment units, incident to dialysis in 1986 and 1987. STUDY DESIGN: This observational study uses baseline patient characteristics in two proportional hazards survival models: the BASE model incorporates age, race, sex, and cause of end-stage renal disease (ESRD); the FULL model includes these and additional clinical information. We compare each model's performance using (1) the c-index, (2) observed median survival in strata of predicted risk, and (3) predicted survival for patients with different characteristics. PRINCIPAL FINDINGS: The FULL model's c-index (0.709, 0.708-0.711) is significantly higher than that of the BASE model (0.675, 0.675-0.676), indicating better discrimination. Second, the sickest patients identified by the FULL model were in fact sicker than those identified as sickest by the BASE model, with observed median survival of 451 days versus 524. Third, survival predictions for sickest patients using the FULL model are one-third shorter than those based on the BASE model. CONCLUSIONS: The model with more detailed clinical information predicted survival better than the BASE model. Clinical characteristics enable more accurate predictions, particularly for the sickest patients. Thus, clinical characteristics should be considered when making quality assessments for dialysis patients

Magnetic vortex dynamics on a picosecond timescale in a hexagonal permalloy pattern

We have observed a motion of magnetic vortex core in a hexagonal Permalloy pattern by means of Soft X-ray microscopy. Pump-probe stroboscopic observation on a picosecond timescale has been carried out after exciting a ground state vortex structure by an external field pulse of 1 ns duration. Vortex core is excited off from the center position of the hexagonal pattern but the analysis of the core trajectory reveals that the motion is nongyrotropic

Judicious Incentives: International Public Policy Responses to the Globalization of Environmental Management

Public policymakers and regulators worldwide are grappling with the desire to improve environmental quality through appropriate regulation of business, while also streamlining government. Concurrently, environmentally conscience consumers are calling for improved environmental performance by industry. As a result of these pressures, regulators and lawmakers worldwide are attempting to craft effective policies that create adequate incentives for environmental protection on the part of firms, in the face of decreasing budgets and an increased demand for the use of market-based incentives. To aid decision makers as they struggle with these concerns, this study provides a detailed case examination of the dilemmas and responses of national-level regulators as they try to develop appropriate responses to the rise of international and "voluntary" management regimes. To accomplish these goals, this article compares the public policy responses of governments around the world to one such voluntary international environmental regime: ISO 14001. ISO 14001 is a form of industry self-regulation in response to market forces calling for harmonization in environmental management and as a result of consumer and trade-partner demands. This study examines the relationships between regulators and the regulated in order to understand if ISO 14001 certified firms are receiving regulatory relief or other forms of public policy/regulatory benefits as a result of their certification. It will also examine the impact that government incentives (or their absence) are having on the certification decisions of firms around the world. This information helps us to begin to understand how the trends toward smaller government and voluntary environmental regimes are affecting one another. Copyright 2006 by The Policy Studies Organization.