Domain structure dynamics of amorphous Fe64Co21B15 and Co77B23 ribbons studied by three-dimensional neutron depolarization

Relaxation phenomena related to domain structure dynamics in amorphous ferromagnetic Fe64Co21B15, and Co77B23 samples were studied by time-resolved three-dimensional neutron depolarization and a conventional magnetic induction technique. Different initial domain structures were induced either by applying external stresses or by stress annealing. A theoretical model was developed to describe the observed time dependence of neutron depolarization upon passage through such samples. It is shown that the domain structure approaches the equilibrium state with stable domain wall positions at a rate that depends essentially both on the sample composition and on the induced magnetic anisotropy. (C) 1999 American Institute of Physics. [S0021-8979(99)01402-4].8521043104

Chances and Limitations of Wild Bird Monitoring for the Avian Influenza Virus H5N1 — Detection of Pathogens Highly Mobile in Time and Space

Highly pathogenic influenza virus (HPAIV) H5N1 proved to be remarkably mobile in migratory bird populations where it has led to extensive outbreaks for which the true number of affected birds usually cannot be determined. For the evaluation of avian influenza monitoring and HPAIV early warning systems, we propose a time-series analysis that includes the estimation of confidence intervals for (i) the prevalence in outbreak situations or (ii) in the apparent absence of disease in time intervals for specified regional units. For the German outbreak regions in 2006 and 2007, the upper 95% confidence limit allowed the detection of prevalences below 1% only for certain time intervals. Although more than 25,000 birds were sampled in Germany per year, the upper 95% confidence limit did not fall below 5% in the outbreak regions for most of the time. The proposed analysis can be used to monitor water bodies and high risk areas, also as part of an early-warning system. Chances for an improved targeting of the monitoring system as part of a risk-based approach are discussed with the perspective of reducing sample sizes

Density functional theory

Density functional theory (DFT) finds increasing use in applications related to biological systems. Advancements in methodology and implementations have reached a point where predicted properties of reasonable to high quality can be obtained. Thus, DFT studies can complement experimental investigations, or even venture with some confidence into experimentally unexplored territory. In the present contribution, we provide an overview of the properties that can be calculated with DFT, such as geometries, energies, reaction mechanisms, and spectroscopic properties. A wide range of spectroscopic parameters is nowadays accessible with DFT, including quantities related to infrared and optical spectra, X-ray absorption and Mössbauer, as well as all of the magnetic properties connected with electron paramagnetic resonance spectroscopy except relaxation times. We highlight each of these fields of application with selected examples from the recent literature and comment on the capabilities and limitations of current methods

Magnetoimpedance aftereffect in a soft magnetic amorphous wire

A slow relaxation of the high-frequency impedance is observed in a Co68.25Fe4.5Si12.25B15 amorphous wire after nucleation of a new domain pattern in a previously saturated sample. The observed impedance decay follows quasilogarithmic kinetics, and it is probably associated with the low-field ac magnetic permeability aftereffect of the circular domain walls. The impedance drop achieves relative amplitudes up to 1%, 16 s after the removal of the saturating external field. The effect is studied under typical magnetoimpedance experimental conditions, varying both the ac current amplitude and frequency. Although completely undesirable for many technical applications, the unique kinetic features of the impedance aftereffect may be explored to study circular magnetization processes under extreme domain-wall velocities.556R3362R336

DISACCOMMODATION MEASUREMENTS IN AMORPHOUS WIRES

Stress dependent magnetic disaccommodation is studied for high and low magnetostrictive amorphous wires and ribbons. The results are interpreted considering the particular domain structure developed in amorphous wires during preparation.104110510

Dipolar-biased giant magnetoimpedance

The effect of the dipolar field on the magnetoimpedance in Fe- and Co-based wires is presented. In the experiments a Co-based wire was used as a probe to measure the giant magnetoimpedance (GMI), while a Fe-based wire was employed to generate the dipolar field. The GMI curve showed a shift in the anisotropy field and a highly asymmetric profile. The dipole-dipole interaction can be employed to design novel linear GMI sensors and to properly tune their field operation. (C) 2005 Elsevier B.V. All rights reserved.295212112

Cu induced coercivity enhancement in the low viscosity GdCo5-xCux system

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)We investigate the influence of Cu substitution, on the coercivity and magnetic viscosity, in the ternary system GdCo5-xCux (x = 0, 0.5, 1, 1.5, 2 and 2.5) with different field sweep rates. All samples have been studied in the as cast state and crystallize in a single phase CaCu5 structure. With Cu addition, the coercivity was 10 times enhanced for x = 1.5. The behavior of the coercivity H-c against field sweep rate, dH/dt, shows that the GdCo5-xCux system exhibits only a small magnetic viscosity effect, a desirable property for magnetic dynamic applications under high magnetic field. (c) 2011 Elsevier B.V. All rights reserved.3231418901894Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)CAPES [029-07