Ab-initio spin dynamics applied to nanoparticles: canted magnetism of a finite Co chain along a Pt(111) surface step edge

In order to search for the magnetic ground state of surface nanostructures we extended first principles adiabatic spin dynamics to the case of fully relativistic electron scattering. Our method relies on a constrained density functional theory whereby the evolution of the orientations of the spin-moments results from a semi-classical Landau-Lifshitz equation. This approach is applied to a study of the ground state of a finite Co chain placed along a step edge of a Pt(111) surface. As far as the ground state spin orientation is concerned we obtain excellent agreement with the experiment. Furthermore we observe noncollinearity of the atom-resolved spin and orbital moments. In terms of magnetic force theorem calculations we also demonstrate how a reduction of symmetry leads to the existence of canted magnetic states.Comment: 4 pages, ReVTeX + 3 figures (Encapsulated Postscript), submitted to PR

Management of hyperlipidaemia

Copyright © 2005 Royal Australian College of General Practitioners Copyright to Australian Family Physician. Reproduced with permission. Permission to reproduce must be sought from the publisher, The Royal Australian College of General Practitioners.BACKGROUND: Hyperlipidaemia is a general term for elevated concentrations of any or all lipids in the plasma. An elevated cholesterol is one of several risk factors for coronary heart disease (CHD). In Australia, the use of cholesterol lowering drugs, mainly statins, consumes over $880 million or 16% of the Pharmaceutical Benefits Scheme drug budget and is growing. OBJECTIVE: This article focusses on primary hypercholesterolaemia, its relationship with CHD, and its management in the community setting. DISCUSSION There is strong evidence that treating middle aged men with statins who have established CHD will reduce overall mortality, CHD morbidity, or mortality and stroke. There is weaker but reasonable evidence for treating men aged over 65 years and women of any age who have CHD, or people without CHD but at high risk. There may be some benefits for patients with stroke and peripheral vascular disease who are at risk of CHD. While discontinuation rates are high, the occurrence of serious adverse reactions are infrequent.Nigel Stocks, James Allan and Peter R. Mansfiel

Injection locking in self-oscillating magnetometers

Injection locking (IL) is a well-known phenomenon that occurs in nonlinear oscillators subject to external periodic or non-periodic signals. It is a phenomenon of induced synchronization that occurs when an external (injection) signal locks the frequency of the oscillator to the frequency of the external signal. This form of synchronization is relatively straightforward to implement because it does not require specially organized feedback as is the case with phase locked loop. Circuits that exploit IL can have very simple designs and be applied to a broad range of applications, such as to synchronize frames and lines in early television sets, to synchronize lasers, and to function as ac voltmeters, field-intensity meters, amplifier-limiters and AM and FM detectors. However, the focus of this article is the recent application of IL to magnetic field sensors. This novel application highlights the potential benefits of the IL approach but also some of the complexities and opportunities for further development. As with all measurement systems, the consideration of noise is paramount in the design of magnetic sensors. Noise reduction and mitigation strategies are essential. IL can be employed as a noise mitigation strategy in magnetometers that utilize self-oscillations as part of their detection paradigm; it can stabilize the oscillation frequency, potentially simplifying the measurement circuitry, and in some circumstances improve the signal-to-noise ratio. Here we review some magnetometers that have successfully exploited IL principles and highlight design options. We also propose a new circuit that is simple to implement and more straightforward to analyze