Comments on "A Cardiac Hypothesis for the Origin of EEG Alpha"

A recent paper by Castillo1 outlines a cardiac hypothesis for the origin of the alpha rhythm. Objections to this and related non-cerebral hypotheses for the generation of EEG alpha are presented in this communication.     

A histological evaluation of the effect of hydroxyapatite coating on interfacial response

The effect of hydroxyapatite (HA) coating on cortical bone apposition around press-fit inserted implants and implants surrounded by a gap was investigated. Uncoated and HA-coated titanium implants were inserted in burr holes with three different diameters in the tibia of rabbits. Implantation time was four months. The histological evaluation demonstrated that after four months implantation the interfacial bone reaction appeared to be identical for HA-coated and non-coated implants with various degrees of surgical fit. Although after four months the interface showed the same response, there still might be an initial advantage of the HA-interface with bony tissue.     

Accurate model for effective dielectric constant of microstrip with validity up to millimetre-wave frequencies

A closed-form expression is presented for the effective dielectric constant of single microstrip lines which is valid with high accuracy up to mm-wave frequencies. The formula given has been designed for use in MIC and MMIC CAD programs as well as in the indirect measurement of substrate permittivities by resonance techniques.     

Advances and perspectives in acne therapy

Acne is one of the most common diseases in dermatology. It is of considerable esthetic significance, which explains the mental stress in affected patients. Although acne almost always heals spontaneously in early adulthood, treatment measures can shorten the course, reduce the severity of the disease, and avoid complications such as scarring. Treatment has changed substantially in recent years. In accordance with pathogenic principles, effective treatment is possible. In most patients, a combination of drugs aimed at correcting abnormal keratinization and reducing the proliferation of Propionibacterium acnes is sufficient to control the disease. For more severely affected patients with no response to this approach, therapy to suppress sebum production is indicated. Of all therapeutic modalities available, only oral isotretinoin alters the natural course of the disease. In acne inversa, surgical management should be undertaken as early as possible.