Magnetic fields and cancer in children residing near Swedish high-voltage power lines

A case-control study was conducted to test the hypothesis that exposure to magnetic fields of the type generated by high-voltage power lines increases cancer incidence in children. The study base consisted of everyone under age 16 years who had lived on a property located within 300 meters of any of the 220 and 400 kV power lines in Sweden during the period 1960-1985. Subjects were followed from their entry into the study base through 1985. A total of 142 cancer cases were identified through a record linkage to the Swedish Cancer Registry. There were 39 leukemia and 33 central nervous system tumor cases. A total of 558 controls were selected at random from the study base. Exposure was assessed by spot measurements and by calculations of the magnetic fields generated by the power lines, taking distance, line configuration, and load into account. Information about historical loads on the power lines was used to calculate the magnetic fields for the year closest in time to diagnosis. When historical calculations were used as exposure assessment for childhood leukemia with cutoff points at 0.1 and 0.2 microtesla (microT), the estimated relative risk increased over the two exposure levels and was estimated at 2.7 (95% confidence interval (CI) 1.0-6.3) for 0.2 microT and over; p for trend = 0.02. When the upper cutoff point was shifted to 0.3 microT, the relative risk was 3.8 (95% CI 1.4-9.3); p for trend = 0.005. These results persisted when adjustment for potential confounding factors was made. For central nervous system tumor, lymphoma, and all childhood cancers combined, there was no support for an association.     

Hygienic evaluation of the electromagnetic field created by high-voltage electric power transmission lines

The authors propose a definitely-arranged system for organization of reanimation and intensive therapy of children. It includes 5 component elements, viz. rooms and posts of reanimation aid at kindergartens and creches, polyclinics and sanatoria; intensive therapy wards at maternity homes and pediatric hospitals; anesthesiological, reanimation and intensive therapy departments of multispecialized pediatric inpatient departments; reanimation and anesthesiological centers; a consultative travelling reanimation pediatric team. The structural form of the patients' hospitalization at pediatric reanimation departments is analyzed. Of their total number 48 per cent are surgical patients after serious operative interventions on the organs of thoracic and abdominal cavities with multiple injuries and malformations; 27.1 per cent are infectious patients, 11.9 per cent - those suffering from poisonings and 10.7 per cent patients with somatic illnesses.     

Calculation of electric fields induced near metal implants by magnetic resonance imaging switched-gradient magnetic fields

Electric (E) fields induced near metal implants by MRI switched-gradient magnetic fields are calculated by a new equivalent-circuit numerical technique. Induced E-field results are found for a metallic spinal-fusion implant consisting of two thin wires connected to the metallic case of a current generator as well as for its subsections: a bare U-shaped wire, an insulated U-shaped wire, a cut insulated wire, and a generator. The presence of the metallic implants perturbs the E field significantly. Near the ends of the bare U-shaped wire, the E field is 89.7 times larger than in the absence of the wire. The greatest E field concentration occurs near the ends of the cut insulated wire, where the E field is 196.7 times greater than in the absence of the wire. In all cases, the perturbation of the induced E field by the implanted wire is highly localized within a few diameters of the wire.     

Flow cytometric analysis of the effects of 50 Hz magnetic fields on mouse spermatogenesis

The cellular effects of an extremely-low-frequency (ELF) magnetic field on mouse spermatogenesis were assessed by DNA flow cytometry and serum testosterone. Seven week old male ICR mice were exposed to a 50 Hz magnetic field the strength of which was 1.0 m Tesla. Seven mice per treatment group were exposed for 13, 26, 39 or 52 days. For each experimental point, an equal number of mice per sham-treated group were used as a control and were exposed only to the background field below 1 mu Tesla in the same room as the treatment group. In the control mice, the testis cellular DNA content distribution by flow cytometory was characterized by four quantifiable populations; round spermatids (1C), spermatogonia and other diploid cells (2C), spermatogonial cells synthesizing DNA (S-phase) and primary spermatocytes (4C). In animals exposed for 26 days the number of cells in the 4C and the 4C:2C ratio was significantly lower, and the 1C:4C ratio (meiotic transformation) was significantly higher than the corresponding control groups. In animals exposed for 52 days the cell population in 1C and the 1C:2C ratio (total germ-cell transformation) was significantly higher, and the cell population in 2C was significantly lower than the corresponding control groups. The concentration of serum testosterone in animals exposed for 13 days was significantly higher than in the corresponding control group. These changes suggest that long-term exposure to an ELF magnetic field had a possible effect on the proliferation and differentiation of spermatogonia.     

Solidification of metallic alloys under magnetic fields

The present paper is aimed at showing how solidification of metallic alloys can be influenced by AC or DC magnetic fields through various types of effects. The application of AC magnetic fields leads to the generation of either fluid flows or vibration. It has been shown both numerically and experimentally that the electromagnetically-driven flows created by travelling or rotating magnetic fields promoted segregations and influenced their distribution. The flow may also promote the CET thanks to its effects on both the temperature and solute fields as well as the possible fragmentation mechanism. As far as DC magnetic fields are concerned, it was known that they usually exert a damping of the bulk fluid flows. However, it has been shown recently that for some alloys high intensity magnetic field interacts with the small thermoelectric current to create significant electromagnetic forces which are responsible for strong liquid metal flows both in the bulk and in the mushy zone. Orientation changes as well as possible modifications of thermodynamic properties were also observed.     

Internal friction characteristics of mixtures of magnetic abrasive powders in magnetic fields

Experiments have been done on the friction in powder magnetic-abrasive tool made up of mixtures of ferroabrasive powders of various types, which differ in composition, properties, and particle size and shape. Regularities are established for the coefficients of internal friction between layers in mixtures. A model relationship is proposed for the structuring of a magnetic abrasive tool containing a powder mixture. Translated from Poroshkovaya Metallurgiya, Nos. 3-4(412), pp. 62–67, March–April, 2000.     

Self-efficacy and marijuana cessation: A construct validity analysis.

Hypotheses regarding the relationships between self-efficacy for avoiding marijuana use and theoretically related measures were examined in a sample of 161 men and 51 women who sought treatment aimed at marijuana cessation. Theoretically proposed sources of efficacy judgments showed stronger univariate and multivariate relationships with efficacy for avoiding marijuana use after treatment than before treatment. The cognitive-behavioral relapse prevention treatment resulted in marginally greater self-efficacy, compared with a nonbehavioral treatment, but the link between coping skill training and efficacy was ambiguous. Efficacy contributed incrementally to the prediction of posttreatment marijuana use beyond efficacy source variables, but it did not completely mediate the effects of those sources of efficacy judgments. Predictive validity was stronger for frequency of posttreatment marijuana use than for abstinence status. The need for better assessment of the efficacy construct and potential revisions in efficacy theory as applied to substance use are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)