A change in the posture of the human body can significantly affect the way in which it absorbs radiofrequency electromagnetic radiation. To study this, an anatomically realistic model of the body has been modified to develop new voxel models in postures other than the standard standing position with arms to the side. These postures were sitting, arms stretched out horizontally to the side and vertically above the head. Finite-difference time-domain (FDTD) calculations of the whole-body averaged specific energy absorption rate (SAR) have been performed from 10 MHz to 300 MHz at a resolution of 4 mm. Calculations show that the effect of a raised arm above the head posture was to increase the value of the whole-body averaged SAR at resonance by up to 35% when compared to the standard, arms by the side position. SAR values, both whole-body averaged and localized in the ankle, were used to derive the external electric field values required to produce the SAR basic restrictions of the ICNIRP guidelines. It was found that, in certain postures, external electric field reference levels alone would not provide a conservative estimate of localized SAR exposure and it would be necessary to invoke secondary reference levels on limb currents to provide compliance with restrictions.
This paper presents calculations of the induced current density in the body at 50 Hz from applied electric and magnetic fields. An extensive ensemble of 25 voxel models has been used to investigate the effects of body posture, anatomy, age and pregnancy. This set includes six adult models, eight child models and seven pregnant female models at various stages of gestation. The four postures investigated in the HPA adult model, NORMAN, were the standard position with the arms at the side, with the arms vertically above the head, the arms horizontally to the side and sitting.
Although radio frequency (RF) electromagnetic fields emitted by mobile phones have received much attention, relatively little is known about the extremely low frequency (ELF) magnetic fields emitted by phones. This paper summarises ELF magnetic flux density measurements on global system for mobile communications (GSM) mobile phones, conducted as part of the MOBI-KIDS epidemiological study. The main challenge is to identify a small number of generic phone models that can be used to classify the ELF exposure for the different phones reported in the study. Two-dimensional magnetic flux density measurements were performed on 47 GSM mobile phones at a distance of 25 mm. Maximum resultant magnetic flux density values at 217 Hz had a geometric mean of 221 (+198/-104) nT. Taking into account harmonic data, measurements suggest that mobile phones could make a substantial contribution to ELF exposure in the general population. The maximum values and easily available variables were poorly correlated. However, three groups could be defined on the basis of field pattern indicating that manufacturers and shapes of mobile phones may be the important parameters linked to the spatial characteristics of the magnetic field, and the categorization of ELF magnetic field exposure for GSM phones in the MOBI-KIDS study may be achievable on the basis of a small number of representative phones. Such categorization would result in a twofold exposure gradient between high and low exposure based on type of phone used, although there was overlap in the grouping.
Syntltetic peptides based on the native human sequen¢~ of surfactant protein B have I~,en used to generate polyclonal monospecific antibodies against specific segments of the native SP-B protein, Circular dichroism analysis or the synthr.tic p, have a dominant helical content in structure promotinll environments and tensiometric measurements indicate these peptides lower surface tension at air=water interfaces implyin~ that they contain amphipathic alpha helical motifs, Antibodies directed aBainst the C-terminal segment of SP.B react with the native protein in the oxidized and reduced state, Antibodies directed against the N.tem~inal sequence of SP-B react with the native protein only in the reduced stat~ suue..aiai| that this domain has a conformation dependent on disulfide bond formation.Surfactant pcptide; Amphtpathie helix: lmmunodominance
This work presents calculations of internal induced electric fields in the anatomically realistic surface-based model of the male human body, MAXWEL, from exposure to external low frequency electric fields under grounded and isolated conditions. The maximum 99th percentile induced electric fields calculated in the MAXWEL central nervous system were 3.49 (grounded) and 1.54 (isolated) mV m(-1) per kV m(-1) at 50 Hz. The application of 2, 1 and 0.5 mm resolution voxel models derived from the surface-based version to the calculations of induced electric fields is described. 2 mm and 1 mm resolution maximum 99th percentile induced electric field values calculated in selected tissues of the eye at 50 Hz were within 30 % of those calculated at 0.5 mm resolution. The calculated electric field values in MAXWEL were compared with values from the male model NORMAN and female model NAOMI. The maximum 99th percentile value for NAOMI, calculated by Dimbylow in bone, was 49.4 mV m(-1) per kV m(-1) at 50 Hz under grounded conditions. The corresponding value calculated in MAXWEL was 15.7 mV m(-1) per kV m(-1), considerably lower due to anatomical differences between the male and female models.
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