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Biomedical subjects

M Izrael

Publications and source records attributed to M Izrael.

8 recordsLinked to original sources
PubMed1994

[The hygienic protective area of the Kaliakra Medium-Wave Radio Station].

A polemics on the ecological expedience of the transmitting station "Kaliakra", which is in the process of building, was held. The two opposing sides in the diaput are OOD "Bulgarian Posts and Power-line Communication" and the community of village Balgarevo, district of Varna. The ecological aspect of the project is very well known in the Ministry of the Environment and the Ministry of Public Health, as well as in the National Center of Hygiene, Medical Ecology and Nutrition. The latter has given an expert attitude for the hazardous zones around the site. As a result of this polemics is the delay of the building, i.e. blocking investments and missed opportunities, because of not realized exploitation. Stating the above we would like to expand the competent forum of the engaged in the problem. For this purpose we are ready to discuss with the participants in the Conference the methods and results of the calculations, as well as the normative basis, which were used in determining the hazardous zone. The control calculations point out, that the level of the electromagnetic exposure of the population in the district will be lower than the allowable values, which are given both in the Bulgarian State Standards and the foreign standard documents for hygiene control of nonionizing radiation.

Bulgaria↗
PubMed1992

[An automated system for the collective protection from harmful exposure to the Veneta superhigh-frequency electromagnetic field of military units and the civilian population].

In the up-to-date exploitation of electromagnetic field generators more and more clearly stands out the problem for radiation protection of people from the biological effect of microwave radiation. In order to solve this problem an automatized system is developed, with the purpose to define according to numerical methods the areas of standardized radiation, where the stay depends on the exposure. On the basis of the developed product are statistical data of the values of the ionized radiation parameters and the algorithm for radiation and hygienic guarantee the exploitation of products emitting superhigh frequency magnetic fields, the average power and strength of the energy flow of which are determined by the impulse power of radiation and measurement in the so called "free area". The system is a first stage for group protection from superhigh frequency electromagnetic field, which afterwards to be approbated by means of apparatus dosimetric examinations.

Algorithms↗
PubMed1987

[Improvement in the hygienic standards for radio-frequency electromagnetic fields in member countries of the COMECON].

The hygienic norms for radiofrequency electromagnetic fields in this country are based on a large number of experimental and industrial studies performed in separate countries and jointly on the CMEA side. Up to 1983 they comprised the widest frequency range in the world - from 60 kHz, 300 GHz, protecting in the best way man. However, these hygienic norms are not perfect: they have steplike frequency dependence, do not include exposure (except at the length of wave under 1 m - microwave range; there are no norms for frequency under 60 kHz, for magnetic field from 1.5 to 30 MHz and from 50-300 MHz do not concern modulated electromagnetic fields and for their combination with other factors of the environment--noise, vibration, overheated microclimate, some toxic substances etc. Therefore, on the side of CMEA two new standards are under preparation, which include the quantity equivalent dose effect in the microwave range--200 W h/cm2, and also report the exposure of the other ranges. This is an advance in the principles of the hygienic standardization, facilitate the hygiene evaluation and are prepared for implementation in our country for the next 2-3 years.

Electromagnetic Fields↗
PubMed1986

[Method for summing up the radio-frequency electromagnetic fields emitted by several sources].

A method has been developed, included in the BSS 14525-78, for measuring and assessment of the radio-frequency electromagnetic field (EMF) at the working places. In a hygienic assessment of fields, emitted from several sources with different frequencies in one premises, it cannot be applied because of the step frequency relationship of the hygienic norms. The same difficulty is encountered in the hygienic assessment of EMF in settlements, where the summing of the from several radio television and other emitters is necessary. With the non-selective measurements of the intensities of EMF (in a broad-frequency range) in such cases, the resultant field of the working place cannot de resolve into component intensities, obtained from the separate generators and hygienic assessment of the determined value cannot be performed. The same concerns also the cases when we separately measure the radiation from each separate emitter--the summing is impossible. If the electromagnetic waves are discussed as flat waves in the free space, a system of 2m equations with 3 m unknown quantities could be worked out after several approximations, where m is the number of the emitting generators in the premises. Furthermore, if consideration is given to the technical devices for measurement of EMF (type of detector), a system of 2 m equations with so many unknown quantities, could be obtained, hence a mathematical method is proposed for its solving. The expression of the intensities of the field is approximated in a polynomial and an original algorithm is proposed for the solving of the system.(ABSTRACT TRUNCATED AT 250 WORDS)

Algorithms↗
PubMed1983

[Combined effect of physical factors in the work environment].

Usually several noxious physical factors of the environment are established under working conditions. The literature data suggest the possible synergetic effect of some of those factors. No criteria exist so far for the prognostication of the effect from the combined activity of the physical factors. All norm documents are based on the data from their isolated effect. Many studies on the combined effect of the most frequently found unfavourably acting physical factors were carried out during the last several years: vibration and noise, local vibration and cooling microclimate, noise and high air temperature, and recently--radiofrequent electromagnetic fields and noise. The alterations in organism were followed up, both under laboratory conditions and at-work experiments, by physiological (peripheral vascular tone, skin thermometry, vibrosensitivity, audiometry, peripheral vision) and by some immunological indices. Some data are presented in the paper, outlining the character of the combined effect of two or more on-the-job physical factors, some mechanisms of affection as well as recommendations for their complex assessment.

Animals↗
PubMed1980

[Changes in arterial elasticity after high-frequency electromagnetic field irradiation].

Results are reported and discussed of elastographic studies in human subjects, irradiated with electromagnetic field, 66 kH frequency and 40 V/m and 0.14 A/m intensities, i.e. with low intensity electric field (borderline normal values for a whole working day). Two types of response to electric field exposure were recorded, depending on the baseline state of the arteries. The changes in the functional state of the vascular system are characterized by signs of hypotonia and vascular tonus changes. The technique of indirect determination of blood vessel elasticity shows a high sensitivity in these weak electromagnetic fildes and may be used in studies on human subjects, professionally exposed to high intensity fields.

Adult↗