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Results for “Geological Phenomena”

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At least 19 recordsLinked to original sources
PubMed1995

Power lines and the geomagnetic field.

The metric of prime interest in power line epidemiological studies has been AC magnetic intensity. To consider also possible geomagnetic involvement, the orientation of a long straight power line is examined relative to a uniform geomagnetic field (GMF) with dip angle alpha. An expression is derived for the component of the total GMF that is parallel, at an elevation beta, to the circuital magnetic field that surrounds the line. This component is a function of the angles alpha and beta, the total geomagnetic intensity BT, and the angle theta between the axis of the power line and magnetic north. Plotting these geomagnetic parameters for known leukemia residences allows one to test for possible ion cyclotron resonance or other GMF interactions. This approach, in principle, is an easy addition to existing or planned studies, because residential access is not required to obtain local values for alpha, beta, theta, and BT. We recommend including these parameters in the design of epidemiological studies examining power line fields and childhood leukemia.

Child↗
PubMedDate not supplied

Cross-spectral coherence between geomagnetic disturbance and human cardiovascular variables at non-societal frequencies.

A 35-year-old cardiologist monitored himself with an automatic ABPM-630 (Colin Electronics) monitor, mostly at 15-minute intervals around-the-clock for three years with a few interruptions. In this subject with a family history of high blood pressure and stroke, a cross-spectral analysis revealed a statistically significant coherence at 27.7 days between systolic and diastolic blood pressure and heart rate vs. the geomagnetic disturbance index, Kp. A lesser peak in coherence was found for systolic blood pressure with Kp at a trial period of 4.16 days (P = 0.046). These results suggest that changes in geomagnetism may influence the human circulation, at least in the presence of familial cardiovascular disease risk, and they may do so at frequencies that have no precise human-made cyclic worldwide match.

Adult↗
PubMed2000

[Did the Erve Valley in Mayenne (the Armoricain Massif, France) play the role of a refuge station during the last (Weichsélien) glaciation?].

Palynological analysis of the basal sedimentary sequence of a peat bog in the upper northeastern part of Mayenne (Massif Armoricain, France) revealed the existence of two temperate oscillations towards the end of the Weichselian glaciation, which were related chronologically by AMS C14 dating to the Kesselt and Tursac interstadials already reported at cave sites. Pollen diagrams recorded mesothermophilic arboreal taxa apparently disseminated from a refuge station possibly corresponding to the Erve valley.

Climate↗
PubMed1980

Natural disasters.

This presentation covers the various types of natural disasters which are faced by investigators throughout the world. Each geophysical substance is discussed, including earth, air and water, and secondary effects including fire. Additionally, four myths associated with disasters are reviewed.

Atmosphere↗
PubMed1981

Soil as the source of trace elements.

The nature of the parent rock determines the trace element content of soils. Ultrabasic and basic rocks, which solidified first from the molten magma, incorporated bioessential trace elements such as Co, Ni, Zn and Cr by isomorphous replacement of Fe and Mg in ferromagnesian minerals, while acidic rocks, the last to solidify, tended to be richer in other elements such as Ba and Pb. Cu, Mn and, to a lesser extent, B, Mo and Se are more evenly distributed. The weathering of rocks by pedological and biological processes such as glacial and hydrodynamic comminution, secretion of acids and liganding species by microbes and plants leads to the formation of sands, silts and clays, and finally the incorporation of organic matter causes humification and the formation of soils as we know them. Part of the soil's store of bioessential elements is held in forms that are available to plants. Availability is controlled by the forms of occurrence and the nature of binding of the trace elements in the soil, which in turn is affected by soil acidity, redox balance (drainage) and organic matter content. These and other factors are discussed along with measures for alleviation of deficiency problems. Future progress in this area will depend to a large extent on interdisciplinary research by biologists, chemists, physicists and statisticians.

Agriculture↗
PubMedDate not supplied

Comparison of upscaling methods to estimate hydraulic conductivity.

A hydraulic field test program was performed at a hard rock laboratory (Aspö HRL) on the Swedish east coast to test upscaling theories. The test program investigated the rock volume around a borehole located at a depth of approximately 340 m below sea level. Hydraulic packer tests were performed at various scales, from 2 m to the entire borehole length of 296 m. From this set of data the predictive ability of different upscaling methods could be evaluated. The comparison of the evaluated "true" field scale hydraulic conductivity with the upscaled hydraulic conductivity yielded that the majority of the upscaling methods tested in this paper predict the large scale values with significant accuracy. However, the ability to predict rapidly decreases when the variance of the natural logarithm of hydraulic conductivity of the subsamples is larger than one. Such a variance is consistently found in the crystalline rocks at the tested site at the 2 m scale. However, at scales of 10 m and larger, a variance larger than one is uncommon. Therefore, it is concluded that there exists a smallest possible scale for use of hydraulic pumping test results for estimating the effective hydraulic conductivity at scales typical for regional flow.

Geological Phenomena↗
PubMed1968

Epidemiological, clinical, and biochemical study of endemic dental and skeletal fluorosis in punjab.

The incidence of dental fluorosis in 46,000 children in the Punjab was assessed and compared with the fluoride content of their water supplies. Ten villages were selected for more detailed studies of skeletal as well as dental fluorosis.Factors other than the fluoride contect of the drinking water which were found to influence the incidence and the severity of fluorosis were the chemical composition of the water and in particular its calcium content; the duration of exposure; sex and occupation; nutritional status; and climatic and geological variations. The role of fluoride-containing foodstuffs has yet to be assessed.

Adolescent↗
PubMedDate not supplied

Progress in space biology.

Over the past two decades there has arisen a new branch of biology--space biology. This short review is devoted to a discussion of its achievements. It considers the results of research in the area of gravitation biology, and an account is made of studies in those areas of radiobiology which have relevance to the study of the cosmos. There is a brief summary of the results of the search for the upper and lower limits of the biosphere, and information is presented regarding the measures employed to maintain planetary quarantine. A great deal of attention has been given to the search for extraterrestrial life, one of the most important of problems. The results obtained with the aid of the American Viking probes on Mars are given special attention. The review presents experimental data based both upon data obtained in experiments on biological specimens during space flights of satellites and space vehicles, and also upon the results of laboratory research.

Air Microbiology↗