The environment in which biology exists has dramatically changed during the last decades. Life was formed during billions of years, exposed to, and shaped by the original physical forces such as gravitation, cosmic irradiation and the terrestrial magnetism. The existing organisms are created to function in harmony with these forces. However, in the late 19th century mankind introduced the use of e

Our group has since 1988 studied the effects of different intensities and modulations of 915MHz RF in a rat model where the exposure takes place in a TEM-cell during various time periods and post exposure recovery times. The power fed into TEM-cells was 0.125, 1.25, 12.5 or 125mW corresponding to whole body SAR (determined experimentally): 0.2, 2, 20 or 200mW/kg. The rats were awake and not restra

A controlled pulsed electrical field applied to a living tissue is believed to cause a structural reorganisation in the lipid bilayer of the cell membranes. This electropermeabilisation or electroporation process is used for opening up the cell membrane in order to get access to the cell. An electrical impedance tissue model that incorporates electroporation is presented. From this model a bio-imp

The aim of the present study is to develop a mathematical model for evaluating therapeutic response of combined treatment modalities. The study was performed in rats of the Fischer-344 strain with rat glioma N32 or N29 tumors implanted subcutaneously on the thigh of the hind leg. Pulsed electric fields, PEF, with 16 exponentially decaying pulses with a maximum electric field strength of 140 V/mm a

The Tundra Ecology -94 expedition investigated inflow of inorganic and organic carbon to the shelf seas by river runoff, and its transformation by biochemical processes in seawater and sediment. In addition, anthropogenic radionuclides, 137Cs, 90Sr, and 239,240Pu, were studied in water and sediments. The distribution of dissolved inorganic carbon indicates that the majority of the Ob and Yenisey d

The objective was to investigate if diffusing laser fibres can be modelled as conductive heat sources without miscalculating coagulated volumes, and if finite element analysis, disregarding light transport, may be used for three dimensional (3D) treatment planning in interstitial laser thermotherapy (ILT). Temperature distributions and coagulated volumes with a diffusing laser fibre, as compared t

The antitumour effect of applied high voltage exponential pulses was investigated on rats with subcutaneously implanted N32 brain tumours. Superficial tumours on the thigh were produced by the injection of 100 000 N32 glioma cells on Fischer-344 rats. Four weeks after inoculation, a solid tumour has grown to a size of about 1 cm located directly under the skin. Short electric high voltage pulses w

Quantitative measurements of blood flow based on magnetic resonance imaging (MRI) using conventional multiple spin echo sequences were evalutated in vivo in healthy young volunteers. Blood flow was measured using MRI in the femoral vein. The initial slope of the multiple spin echo decay curve, corrected for the T2 decay of non-flowing blood was used to calculate the blood flow. As a reference, the

The magnetic properties of 12 different types of aneurysm clip were investigated in order to identify which clips allow postoperative magnetic resonance (MR) imaging without risk. Clip-induced MR artifacts were also quantitatively studied using a geometrical phantom. Nonferromagnetic aneurysm clips like the Yasargil Phynox, Sugita Elgiloy, and Vari-Angle McFadden clips do not appear to contraindic

The purpose of this study was to evaluate a method for the quantification of through-plane flow velocities by magnetic resonance imaging (MRI) from the flow characteristics of conventional multiple spin-echo (MSE) signals. Simulated inflow-outflow-dependent signals, as well as images of a flow phantom were generated and the logarithm of the flow-dependent signal value was plotted against echo time

Our previous studies have shown that incomplete white matter infarctions are common in senile dementia of the Alzheimer type. To visualize and interpret these changes on magnetic resonance imaging (MRI), knowledge of MR relaxation times associated with this histopathology is important. The proton MR relaxation times T1 and T2 were determined in vitro for 3 groups of specimens. Fifty specimens of n

A basic theoretical model that describes the effects of flow in and out of the imaging plane in nuclear magnetic resonance (NMR) images, obtained with the standard pulse sequences single spin echo, multiple spin echo, and inversion recovery, is presented. Theoretically calculated signal values are compared with experimental results obtained from single-slice images of a flow phantom for variable f

Proton MR relaxation times T1 and T2 were determined in vitro in 136 small specimens of astrocytomas grades I-IV, of oligodendrogliomas, metastases of adenocarcinomas, meningiomas and acoustic neuromas. In addition, 7 samples of peritumoural white matter were analysed. The analysed specimens were studied microscopically in their entirety regarding tumour type and occurrence of necrosis and non-tum

Plutonium and americium have been measured in surface waters of the Greenland and Barents Seas and in the northern North Sea from 1980 through 1984. Measurements in water and biota, Fucus, Mytilus and Patella, were carried out in North-English and Scottish waters in 1982 and Fucus samples were collected from the Irish coast in 1983. Fallout is found to dominate as a source of 239+240Pu north of la

The aim of this study was to compare the influence of flow in the velocity range 0 to 25 mm/s on modulus, phase, real and imaginary images obtained with a standard magnetic resonance scanner (Siemens Magnetom, 0.5 T), and to develop a simple method for determination of flow velocities in vivo from this information. Using a flow phantom, the flow dependent magnetic resonance imaging (MRI) signal ha

In order to establish the validity of in vitro determination of the proton magnetic resonance (MR) relaxation times T1 and T2 in brain tissue at increasing time delay after death or operative excision, 81 brain tissue samples from 23 pigs were analyzed repeatedly. These samples, representing cortex, caudate nucleus and white matter, were studied microscopically after MR measurements. The T1 values