Björn Bergqvist

Cytoplasmic Ca2+ oscillations in human leukemia T-cells are reduced by 50 Hz magnetic fields.

The effect of 50 Hz magnetic fields on the cytosolic calcium oscillator in Jurkat E6.1 cells was investigated for field strengths within the range from 0 to 0.40 mT root mean square. The intracellular Ca2+ concentration data were collected for single Jurkat cells that exhibited a sustained spiking for at least 1 h while repeatedly exposing them to an alternating magnetic field in 10-min intervals interposed with nonexposure intervals of the same length. The obtained data were analysed by computing spectral densities of the Ca2+ oscillating patterns for each of these 10-min intervals. For every single-cell experiment the spectra of all exposure as well as nonexposure periods were then averaged separately. A comparison between the resulting averages showed that the total spectral power of the cytosolic Ca2+ oscillator was reduced by exposure of the cells to an alternating magnetic field and that the effect increased in an explicit dose-response manner. The same relationship was observed within the 0-10 mHz (10 x 10(-3) Hz) subinterval of the Ca2+ oscillation spectrum. For subintervals at higher frequencies, the change caused by the exposure to the magnetic field was not significant.

The influence of 50-Hz magnetic fields on cytoplasmic Ca2+ oscillations in human leukemia T-cells

We have studied the effects of 50-Hz 100-microT rms magnetic fields on intracellular Ca2+ concentration in the Jurkat T lymphocyte variant E6.1 using fluorescent probes Indo-1 and Fura-2. We found, however, that the pattern of intracellular Ca2+ fluctuations also depended on the agent used for cell attachment, in our case the polypeptide poly-L-lysine. In order to isolate possible effects of magnetic field exposure from those of poly-L-lysine, the action of polypeptide on cytosolic Ca2+ was studied as well. It was found that a 10(-7)% concentration of polypeptide triggered prolonged Ca2+ spiking. Higher (10(-4)%) concentrations induced rapid increases in intracellular Ca2+ followed by high, unstable Ca2+ levels. The response of these cells to the monoclonal antibody anti-CD3 was also inhomogeneous, similar to one caused by poly-L-lysine. The effect of magnetic field exposure was studied on cells initially exhibiting (1) non-oscillating, low Ca2+ concentration and (2) prolonged Ca2+ concentration oscillations. In case (1) the result was negative. In case (2), statistically significant changes were found: the oscillation amplitude was reduced on average by 30%, and the frequency composition was shifted towards higher frequencies.

Measurement Uncertainty, Channel Simulation, and Disturbance Characterization of an Over-the-Air Multiprobe Setup for Cars at 5.9 GHz

Over-the-air (OTA) multiprobe setups provide an efficient way to characterize the performance of todays advanced wireless communication systems. In this paper, the measurement uncertainty of such a setup using a car as a test object is characterized through three experiments: measurement system analysis, channel sounder measurements, and probe coupling measurements. Four issues were in focus for the analysis: precision, realization of the wireless communication channel, coupling between the probes, and the influence of the test object size. The analysis shows that a large test object such as a car in an OTA multiprobe ring will affect the measurement uncertainty, but only to a small degree. The measurement uncertainty expressed as expanded uncertainty was below +/-1 dB, which is a level that would not violate best practice total uncertainty levels for comparable OTA methods.

Effect of microwave radiation on permeability of liposomes. Evidence against non-thermal leakage

The effect of 2.45 GHz microwave radiation on the permeability of unilamellar phosphatidylcholine liposomes has been studied. Leakage of 5(6)-carboxyfluorescein from the liposomes was measured using spectrofluorimetry after exposure to either microwaves or thermal heating for 5-20 min intervals. The exposure temperature, 37.6 +/- 0.5 degrees C, was well above the phase transition temperature of the lipid membrane. The microwave exposure did not result in any non-thermal increase in permeability above that produced by thermal heating. This study refutes the results reported by Saalman et al. [1] in which an increased liposome permeability due to microwave exposure was reported. The refined analysis in the present study shows that this increased liposome permeability was not a non-thermal microwave effect.

Aerodynamic Effects of Roof Deflector and Cab Side Extenders for Truck-Trailer Combinations

Today there are a large variety of drag reducing devices for heavy trucks that are commonly used, for example roof deflectors, cab side extenders and chassis fairings. These devices are often proven to be efficient, reducing the total aerodynamic resistance for the vehicle. However, the drag reducing devices are usually identical for a specific pulling vehicle, independent of the layout of the vehicle combination. In this study, three vehicle combinations were analyzed. The total length of the vehicles varied between 10.10m and 25.25m. The combinations consisted of a rigid truck in combination with one or two cargo units. The size of the gap between the cargo units differed between the vehicle combinations. There were also three configurations of each vehicle combination with different combinations of roof deflector and cab side extenders, yielding a total number of nine configurations. The aim of this investigation was to determine the aerodynamic effects of the roof deflector and cab side extenders as a function of the type of vehicle combination. Important factors were the total length of the vehicle combination and the influence of the drag reducing devices further downstream. The investigation was performed using Computational Fluid Dynamics (CFD). The results from the investigation showed that the effect of the two drag reducing devices analyzed was different depending on the type of vehicle combination. It was established that the roof deflector and cab side extenders were always efficient in reducing drag both in 0° yaw and 5° yaw but the magnitudes differed between the configurations. The largest effects of the drag reducing devices were seen for the truck including the 1st cargo unit; the influence of the drag reducing devices on the 2nd cargo unit was smaller. The aerodynamic reductions were diminishing downstream, why it was concluded that it is of great importance to improve the aerodynamic design of the rest of the vehicle to maintain the positive effects of the drag reducing devices.

Influence of Different Truck and Trailer Combinations on the Aerodynamic Drag

The aim with this investigation was to study the aerodynamic properties of truck-trailer combinations of varying lengths. The aerodynamic properties of the combinations were evaluated in order to study similarities and differences in the flow field between different configurations. By the use of Computational Fluid Dynamics (CFD) six different types of truck-trailer combinations used for long hauling have been evaluated. The combinations have a total length varying between 10.10 m and 25.25 m and consist of either a tractor or rigid truck in combination with one or two cargo units. All of the combinations are commonly found on roads in Sweden and several other countries in Europe. The results from the simulations show that the aerodynamic properties differ significantly for the truck-trailer combinations. It was found that the longer vehicle combinations are much more sensitive to yaw conditions than the shorter combinations. What was also evident is that the gap between the first and second cargo unit plays a significant role for the aerodynamic properties. Furthermore it was established that there is potential for fuel saving by a strategic choice of truck-trailer combination. According to the simplified evaluation made in this study the 25.25 m combinations show a lower power required per loading length (LL) and are therefore shown to be more efficient than the shorter combinations.

Impact of different interference types on an LTE communication link using conducted measurements

Measurements have been used for the analysis of an LTE system, which may be used for vehicle applications. The analyzed system consists of an LTE communication tester simulating a base station and a mobile phone. To obtain repeatable measurement results the RF ports of the communicating nodes were connected with cables. The susceptibility of the mobile to interfering signals with various characteristics (CW, AM, FM and Pulse modulation) has been investigated. The result shows that interference on frequencies close to the center of data subcarriers is less severe than on frequencies further apart from the center. For the interfering signals on the pilot subcarrier a simple regression model based on the measurements has been calculated.

European Truck Aerodynamics – A Comparison Between Conventional and CoE Truck Aerodynamics and a Look into Future Trends and Possibilities

The aerodynamic situation for trucks on the European market differs from that in North America on a number of points. Perhaps the most significant difference is that in Europe trucks are of the CoE configuration (Cab over Engine) and in North America trucks are of the conventional type with a hood. Another major difference is that trucks in Europe are speed limited to 90 km/h (56 mph) which of course means that aerodynamics as a whole has less of an impact there. These differences are primarily dictated by different legislations, which in turn have a lot of different side effects. This paper will high-light some of the differences and their impact on aerodynamics, as well as taking a look at possible future ideas such as: extended front or short nose, ride height adjustments, convoy driving, etc.

Large eddy simulation of the tidal power plant Deep Green using the actuator line method

Tidal energy has the potential to provide a substantial part of the sustainable electric power generation. The tidal power plant developed by Minesto, called Deep Green, is a novel technology using a ‘flying’ kite with an attached turbine, moving at a speed several times higher than the mean flow. Multiple Deep Green power plants will eventually form arrays, which requires knowledge of both flow interactions between individual devices and how the array influences the surrounding environment. The present study uses large eddy simulations (LES) and an actuator line model (ALM) to analyze the oscillating turbulent boundary layer flow in tidal currents without and with a Deep Green power plant. We present the modeling technique and preliminary results so far.