Superficial magnetic imaging by an xy-scanner of three magnetoresistive channels.

A scanning system developed for planar magnetic surfaces composed of a moving line of three magnetoresistive ultrasensitive transducers, complemented by a signal conditioning circuit is presented. After the calibration of the sensors, it was used to determine magnetized surface images with different shapes to evaluate the sensitivity of the device, and the images are represented in gray levels on a scale from 0 to 255 intensities, to get a visual representation of the magnetic field strength. The device is shown to be sensitive enough to detect gradients homogeneities and discontinuities in the magnetic field maps and images of magnetic susceptibility.

[Dropouts from orthodontic treatment. Factors which cause it]. / El abandono del tratamiento ortodoncico. Causas que lo originan.

Dropout of orthodontic treatment is something common in our services, but up to here, its possible causes have not been determined, therefore, a study is performed to a group of patients who had deserted from "La Vigía" Teaching Stomatologic Clinics, Department of Orthodontics, and who was on admission during 1981 and 1982. It was found that 18.9% of the patients on admission had interrupted treatment. A questionnaire related to possible causes of dropout was applied to the group and the most common causes for given up to treatment were detected: the patient was poorly motivated and lack of information on some important aspects of treatment on the part of the orthodontist.