Effect of nonuniform perpendicular anisotropy in ferromagnetic resonance spectra in magnetic nanorings.

The high frequency dynamic behaviors of magnetic nanorings with variable anisotropy along their radius have been studied using micromagnetic simulations. The dynamic susceptibility spectrum and spatial localization of the ferromagnetic resonance modes are investigated by varying anisotropy gradients in nanorings of 200 nm of external radius, with different internal radii. Both the resonant frequencies and the number of peaks depend on the lower energy magnetization configuration which in turn is a function of anisotropy gradients. Besides, it is shown that the effects of the anisotropy gradient are relevant even for the narrowest ring of 10 nm wide. The idea of controlling frequencies by modifying the anisotropy gradients of the system suggests the possibility of using these nanostructures in potential magnetic controllable frequency devices.

Dynamic and static properties of stadium-shaped antidot arrays.

In this work we performed a detailed numerical analysis on the static and dynamic properties of magnetic antidot arrays as a function of their geometry. In particular, we explored how by varying the shape of these antidot arrays from circular holes to stadium-shaped holes, we can effectively control the magnetic properties of the array. Using micromagnetic simulations we evidenced that coercivity is very sensitive to the shape of antidots, while the remanence is more robust to these changes. Furthermore, we studied the dynamic susceptibility of these systems, finding that it is possible to control both the position and the number of resonance peaks simply by changing the geometry of the holes. Thus, this work provides useful insights on the behavior of antidot arrays for different geometries, opening routes for the design and improvement of two-dimensional technologies.

A soft/hard magnetic nanostructure based on multisegmented CoNi nanowires.

In this paper we have introduced a new soft/hard nanostructure based on multisegmented CoNi nanowire arrays having diameters of around 110 nm and made of five segments with nominal compositions of Co, Co66Ni33, Co50Ni50, Co33Ni66 and Ni, each of which has a length of 800 nm, so that the total length of the multisegmented nanowire is 4 µm. These arrays have been synthesized by means of potentiostatic electrodeposition into the pores of hard-anodic alumina templates. The morphology, chemical composition and microstructure of the multisegmented CoNi nanowires were determined by high-resolution scanning electron microscopy, energy dispersive X-ray microanalysis, and powder X-ray diffraction method, respectively. The room temperature magnetic behavior of the multisegmented nanowire arrays is also studied and compared with CoNi nanowire arrays with homogeneous composition (non-segmented nanowires), synthesized in the same templates and having the same dimensions as the segmented ones. These nanostructures could be used to control the movement of magnetic domain walls. In this way, these nanostructures can be an alternative to store information or even perform logic functions.

Geometry dependence of coercivity in Ni nanowire arrays.

Magnetic properties of arrays of nanowires produced inside the pores of anodic alumina membranes have been studied by means of vibrating sample magnetometer techniques. In these systems the length of the wires strongly influences the coercivity of the array. A simple model for the coercivity as a function of the geometry is presented which exhibits good agreement with experimental results. Magnetostatic interactions between the wires are responsible for a decrease of the coercive field.

Occupational rhinoconjunctivitis and asthma caused by Tetranychus urticae (red spider mite). A case report.

This paper highlights a clinical case of a patient suffering bronchial asthma and rhinoconjunctivitis due to sensitization to Tetranychus urticae (TU), commonly known as the red spider mite, which belongs to the Prostigmata sub-order of the Tetranychidae family, in relation to a work environment (a carnation nursery). Both prick and intradermal skin tests were positive, as well as specific bronchial challenge tests with TU extract. Specific IgE was demonstrated by RAST (Class 3). Unspecific bronchial provocation with methacholine was negative. Sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) immunoblotting revealed the presence of seven main IgE binding proteins, the more intense bands being those appearing at 21, 17 and 15 kDa. This indicates a case of immediated type hypersensitivity to Tetranychus urticae with a clear correlation to occupational environment.

Plasma kallikrein amidolytic activity in patients with urticaria.

We have studied the plasma kallikrein amidolytic activity in healthy control subjects (inactive), patients with chronic urticaria (active) and patients with acute urticaria (active) from their admission to the emergency room (active) to the time after which their clinical symptomatology had disappeared (inactive). We found statistically significant differences (p < 0.01) in the active groups of urticaria patients. This leads us to believe that kallikrein participates in the development of symptomatology in these patients.

Ambulatory monitoring of blood pressure and arrhythmias by non-invasive methods in hypertensive patients treated with metoprolol.

Non-invasive ambulatory monitoring of blood pressure and ECG was employed to assess the 24-hour profile of blood pressure and arrhythmias in 20 out-patients aged 31-69 years. The technique was further used to measure the therapeutic response to 100 mg once daily of the cardioselective beta-blocker metoprolol. The basal ambulatory examinations revealed that all 20 patients had a mean 24-hour blood pressure of greater than 160/90 mm Hg, corresponding to a mean arterial pressure (MAP) of greater than 113 mm Hg. In 16 of the 20 patients (80%) the mean 24-hour MAP was reduced to below 113 mm Hg. Addition of diuretics in the remaining four patients further decreased the mean 24-hour MAP to less than 113 mm Hg, which confirmed by a third ambulatory examination. The ECG recordings in the initial ambulatory study revealed severe degrees of ventricular arrhythmias in 7 patients. After treatment with metoprolol, all of them presented an improved ECG picture.