Quantitative Scaling of Magnetic Avalanches.

We provide the first quantitative comparison between Barkhausen noise experiments and recent predictions from the theory of avalanches for pinned interfaces, both in and beyond mean field. We study different classes of soft magnetic materials, including polycrystals and amorphous samples-which are characterized by long-range and short-range elasticity, respectively-both for thick and thin samples, i.e., with and without eddy currents. The temporal avalanche shape at fixed size as well as observables related to the joint distribution of sizes and durations are analyzed in detail. Both long-range and short-range samples with no eddy currents are fitted extremely well by the theoretical predictions. In particular, the short-range samples provide the first reliable test of the theory beyond mean field. The thick samples show systematic deviations from the scaling theory, providing unambiguous signatures for the presence of eddy currents.

On the nature of the interlayer magnetic interactions in biphase ferromagnetic films.

We report on the nature of the interlayer magnetic interactions in NiFe/Cu/Co films. By probing the quasi-static and dynamic magnetic properties of biphase ferromagnetic films, with soft and hard ferromagnetic phases intermediated by a non-magnetic layer, we address aspects of the coupling between magnetic layers. Our results demonstrate the nature of the interlayer magnetic coupling in biphase films. We also disclose the asymmetric magnetoimpedance effect as a fingerprint of the nature of the magnetic interlayer interactions playing key role in the magnetization dynamics of the system. We revisit in literature data and ideas on the asymmetric magnetoimpedance and the nature of the magnetic interactions in biphase ferromagnetic systems. Then, we compare our findings with results for biphase ribbons and microwires. Our observations raise the fundamental similarities and differences in the asymmetric magnetoimpedance of these structures.

Magnetic nanoparticles hyperthermia in a non-adiabatic and radiating process.

We investigate the magnetic nanoparticles hyperthermia in a non-adiabatic and radiating process through the calorimetric method. Specifically, we propose a theoretical approach to magnetic hyperthermia from a thermodynamic point of view. To test the robustness of the approach, we perform hyperthermia experiments and analyse the thermal behavior of magnetite and magnesium ferrite magnetic nanoparticles dispersed in water submitted to an alternating magnetic field. From our findings, besides estimating the specific loss power value from a non-adiabatic and radiating process, thus enhancing the accuracy in the determination of this quantity, we provide physical meaning to a parameter found in literature that still remained not fully understood, the effective thermal conductance, and bring to light how it can be obtained from experiment. In addition, we show our approach brings a correction to the estimated experimental results for specific loss power and effective thermal conductance, thus demonstrating the importance of the heat loss rate due to the thermal radiation in magnetic hyperthermia.

Universal temporal characteristics and vanishing of multifractality in Barkhausen avalanches.

Barkhausen effect in ferromagnetic materials provides an excellent area for investigating scaling phenomena found in disordered systems exhibiting crackling noise. The critical dynamics is characterized by random pulses or avalanches with scale-invariant properties, power-law distributions, and universal features. However, the traditional Barkhausen avalanches statistics may not be sufficient to fully characterize the complex temporal correlation of the magnetic domain walls dynamics. Here we focus on the multifractal scenario to quantify the temporal scaling characteristics of Barkhausen avalanches in polycrystalline and amorphous ferromagnetic films with thicknesses from 50 to 1000 nm. We show that the multifractal properties are dependent on film thickness, although they seem to be insensitive to the structural character of the materials. Moreover, we observe for the first time the vanishing of the multifractality in the domain walls dynamics. As the thickness is reduced, the multifractal behavior gives place to a monofractal one over the entire range of time scales. This reorganization in the temporal scaling characteristics of Barkhausen avalanches is understood as a universal restructuring associated to the dimensional crossover, from three- to two-dimensional magnetization dynamics.

Statistical properties of Barkhausen noise in amorphous ferromagnetic films.

We investigate the statistical properties of the Barkhausen noise in amorphous ferromagnetic films with thicknesses in the range between 100 and 1000 nm. From Barkhausen noise time series measured with the traditional inductive technique, we perform a wide statistical analysis and establish the scaling exponents τ,α,1/σνz, and ϑ. We also focus on the average shape of the avalanches, which gives further indications on the domain-wall dynamics. Based on experimental results, we group the amorphous films in a single universality class, characterized by scaling exponents τ=1.28±0.02,α=1.52±0.3, and 1/σνz=ϑ=1.83±0.03, values compatible with that obtained for several bulk amorphous magnetic materials. Besides, we verify that the avalanche shape depends on the universality class. By considering the theoretical models for the dynamics of a ferromagnetic domain wall driven by an external magnetic field through a disordered medium found in literature, we interpret the results and identify an experimental evidence that these amorphous films, within this thickness range, present a typical three-dimensional magnetic behavior with predominant short-range elastic interactions governing the domain-wall dynamics. Moreover, we provide experimental support for the validity of a general scaling form for the average avalanche shape for non-mean-field systems.

Multifractality in domain wall dynamics of a ferromagnetic film.

We investigate the multifractal properties in the dynamics of domain walls of a ferromagnetic film. We apply the Multifractal Detrended Fluctuation Analysis method in experimental Barkhausen noise time series measured in a 1000-nm-thick Permalloy film under different driving magnetic field frequencies, and calculate the fluctuation function F_{q}(s), generalized Hurst exponent h(q), multifractal scaling exponent τ(q), and the multifractal spectrum f(α). Based on this procedure, we provide experimental evidence of multifractality in the dynamics of domain walls in ferromagnetic films and identify a rich and strong multifractal behavior, revealed by the changes of the scaling properties of over the entire Barkhausen noise signal, independently of the driving magnetic field rate employed in the experiment.

[A clinical study of examples of variability and instability of fixed sections of canine EKGs]. / Beispiele zur Variabilität und Labilität bestimmter Abschnitte des Hunde-EKGs, ein klinischer Beitrag.

Study in ECGs of a clinical collection of 45 dogs (15 dogs without heart disease and without sedation or anesthesia, 15 dogs with acquired and congenital heart disease without sedation or anesthesia, 15 dogs premedicated and anesthetised and all dogs except one without heart disease). Especially studied were the parts which are known in the ECG of the dog as variable and labile (ST-segment, ST-segment-junction and the T-wave). In the group of premedicated and anesthetised dogs a curved and arched ST-segment was more often observed as in comparison to the other two groups. On the other hand the ECG evaluations showed that in all studied groups independent of the status of the heart many similar or equal configurations of the variable and labile parts of the ECG were observed.

[Comments on computer programs and their use as educational aids for veterinary practice]. / Bemerkungen zu Computerprogrammen und deren Nutzung als Ausbildungshilfe für die Praxis.

Comparisons to older educational methods are drawn. Common aspects of computer supported programs and their handling at training and development for the practice are being discussed. Different problems of new methods of informatics are shown.

[Adams-Stokes syndrome and therapy with pacemaker implantation in a dog]. / Adams-Stokes-Syndrom und Therapie mit Schrittmacherimplantation bei einem Hund.

Case report concerning therapeutic pacemaker implantation in a 3 year old West-Highland-White terrier with Adams-Stokes syncopes. EKG's, X-ray-pictures, illustrations of the pulse rate and quality and oxygen measurements with a "Pulsoximeter" before and during surgery are shown. A special place takes the report of selection and control of the anesthesia in this case of a special operation. 17 references and 11 pictures.

[Anticholinergic medication in the dog before and during anesthesia]. / Studien zur anticholinergen Medikation beim Hund vor und während Anästhesien.

In clinical studies in dogs of all categories of age, which were predicted for surgical purposes under a combination anaesthesia with Fluanisone/Fentanyl/Nitrous oxide/Halothane, investigations after treatment with atropine or glycopyrrolate were performed. In experimental studies investigations about heart-rate and heart work (rate-pressure-product RPP) under different injection anaesthesia-methods (Fluanisone/Fentanyl/Metomidate, Climazolam/Fentanyl, Xylazine/l-Methadone) are performed. In the clinical studies many of the dogs produce elevated heart-rates after anticholinergic premedication. After special indicated treatment of dysrhythmias with glycopyrrolate or atropine in all cases normorhythmia can be achieved. An increase in heart rate during awaking time can be seen in non premedicated as well as in anticholinergic treated animals for a short period of time. In the experimental studies the anticholinergic treatment leads to increased heart rate and/or elevated arterial pressure, which produce an enormous increase in the rate pressure product and oxygen consumption. In conclusion a general anticholinergic premedication can not be recommended. Its use should be special indicated for bradycardia and/or dysrhythmias in the sense of AV-conduction disturbances.

[Cardiology for the veterinary practice--information processing with the help of a computer program, with a working example]. / Kardiologie für die Tierarztpraxis--Wissensverarbeitung mit Hilfe eines Computerprogramms, mit Bearbeitungsbeispiel.

Description of a PC-Program "Cardiology for the Veterinary Practice", title "Kardiag", with Illustrations and a report of a congenital heart disease in a one year old, male, Newfoundland dog, with the use of the described PC-Program. After euthanasia an autopsy was performed which verified the clinical diagnosis.