Exposure to GSM RF fields does not affect calcium homeostasis in human endothelial cells, rat pheocromocytoma cells or rat hippocampal neurons

In the course of modern daily life, individuals are exposed to numerous sources of electromagnetic radiation that are not present in the natural environment. The strength of the electromagnetic fields from sources such as hairdryers, computer display units and other electrical devices is modest. However, in many home and office environments, individuals can experience perpetual exposure to an "electromagnetic smog", with occasional peaks of relatively high electromagnetic field intensity. This has led to concerns that such radiation can affect health. In particular, emissions from mobile phones or mobile phone masts have been invoked as a potential source of pathological electromagnetic radiation. Previous reports have suggested that cellular calcium (Ca2+) homeostasis is affected by the types of radiofrequency fields emitted by mobile phones. In the present study, we used a high-throughput imaging platform to monitor putative changes in cellular Ca2+ during exposure of cells to 900 MHz GSM fields of differing power (specific absorption rate 0.012-2 W/Kg), thus mimicking the type of radiation emitted by current mobile phone handsets. Data from cells experiencing the 900 Mhz GSM fields were compared with data obtained from paired experiments using continuous wave fields or no field. We employed three cell types (human endothelial cells, PC-12 neuroblastoma and primary hippocampal neurons) that have previously been suggested to be sensitive to radiofrequency fields. Experiments were designed to examine putative effects of radiofrequency fields on resting Ca2+, in addition to Ca2+ signals evoked by an InsP(3)-generating agonist. Furthermore, we examined putative effects of radiofrequency field exposure on Ca2+ store emptying and store-operated Ca2+ entry following application of the Ca2+ATPase inhibitor thapsigargin. Multiple parameters (e.g., peak amplitude, integrated Ca2+ signal, recovery rates) were analysed to explore potential impact of radiofrequency field exposure on Ca2+ signals. Our data indicate that 900 MHz GSM fields do not affect either basal Ca2+ homeostasis or provoked Ca2+ signals. Even at the highest field strengths applied, which exceed typical phone exposure levels, we did not observe any changes in cellular Ca2+ signals. We conclude that under the conditions employed in our experiments, and using a highly-sensitive assay, we could not detect any consequence of RF exposure

Experiments on the Velocity Field Around a Low Aspect Ratio Wing at Low Reynolds Numbers

The flow structure around a low aspect ratio wing at low Reynolds numbers and a fixed angle of attack of 20° is discussed using flow visualization as well as Three-Component Time-Resolved Particle Image Velocimetry (3C TR PIV). Mean quantities and statistical measurements of velocity were obtained and used to describe the average and transient characteristics of the flow field. Effects of spanwise variation from centerline to wingtip and Reynolds number variation from 1.3×104 to 6.6×104 are discussed. The role of the wing tip vortices is observed to be large in a low aspect ratio wing. The transfer of momentum via Reynolds shear stresses is shown in the leading edge region. Normalized spanwise shear stresses associated with the wing tip vortices are observed to increase with increasing Reynolds number.</jats:p

Mean Flow Characteristics of a Turbulent Offset Jet

A detailed study of the mean flow characteristics of a turbulent offset jet is presented. The flow is characterized by a longitudinal variation of curvature, skewed impingement onto a flat surface, a recirculating region, and the development of a wall jet region. Flow structure is described in the preimpingement, recirculation and impingement regions. An interdependence is shown among the pressure differential across the jet, jet curvature and entrainment. The magnitude of the curvature strain rate is found to be significant and implies that this flow cannot be accurately modelled as a thin shear layer. The jet decay and spread rates are similar to those of a plane jet if appropriate curved coordinates are used. The extent of the impingement region is approximately 20 nozzle widths downstream, in agreement with previous studies.</jats:p