Catálogo de publicaciones - libros

Measurement optimization is being studied when short voltage pulses are stimulating bio-tissue and the transient process is sampled in order to measure the tissue volume changes. The measurement sensitivity depends on the ratio of the sampling instant to the time constant of the transient process, ( T /τ) and on the ratio of the current sensing resistance to the resistance of the electrode-skin interface ( R _0/ R _ SX ). With variations of R _0/ R _ SX and T /τ the sensitivity changes from negative to positive values, while it equals zero for certain R _0/ R _ SX and T /τ ratios. The sensitivity is greater when positive while than negative but it depends on T /τ and R _0/ R _ SX . For negative sensitivity, T and R _0 can be chosen to maximize the sensitivity and minimize its variations.

The experiments on the effect of modulated microwaves on human EEG were carried out on two different groups of 14 and 7 healthy volunteers exposed to 450 MHz microwave radiation modulated at 40 and 1000 Hz frequencies. The field power densities at the scalp were 0.16 mW/cm for the first and 0.9 mW/cm for the second group. The EEG analysis performed for individuals showed that increase in the EEG rhythm energy in both groups was comparable: up to 40% at lower and up to 30% at higher level of the field power density. Microwave caused statistically significant changes in the EEG rhythms energy for 20% of subjects in the first and for 14% of subjects in the second group. Our results suggested that effect of microwave on EEG didn’t enlarged with increase of the applied power density.

Many in vivo and in vitro studies have been performed to investigate the biological consequences and to assess health risks of RFR (Radio Frequency Radiation) generated from mobile phones. Mechanism of RFR and oxidative damage and the question if antioxidants taken as nutrition can alter the oxidative damage of mobile phone damage are popular subjects tried to investigate. In this study, it was aimed to investigate whether the antioxidative effects of green tea catechins can inhibit RFR- induced free radical releases causing oxidative damage of proteins in guinea pigs’ liver tissue. RFR generated by mobile phone with 0.81 W/kg digital SAR value operating in GSM 1800 MHz frequency. Male Guinea pigs were exposed to mobile phone radiation averaged as 11.2 V/m, measured during exposure for 20 minutes in 7 days of a week. Activities of antioxidant enzymes such as superoxide dimutase (SOD), glutathione peroxidase (GSH-Px), and level of malondialdehyde (MDA) were measured in liver guinea pigs which divided into four groups as control, EGCG-treated, mobile phone-exposed and both mobile phone-exposed and EGCG-treated. As a result, both antioxidant enzyme activities and free radical levels of the mobile phone exposed and mobile phone exposed with EGCG groups changed significantly ( p < 0.05).

To give the Slovenian communes and their inhabitants the possibility to obtain information about electromagnetic fields in their neighborhood, Forum EMS – an independent project aimed to inform general public about electromagnetic fields and their biological effects – started monitoring campaign in 2005. In communes expressed the interest, remote monitoring station was installed for one week. The value of electric field intensity was stored every minute 24 hours a day and. For each location all collected data were evaluated and presented to the interested public as an article in commune bulletin and on internet, where the data for all locations are available. In last two years more than 35 communes participated in this campaign. The monitoring campaign showed that typical electromagnetic field exposure due to GSM base stations in urban area is low. Maximum values reach 2 % of reference level for I. region of Slovenian legislation, which is 0.2 % of ICNIRP reference level for general public. Due to the vicinity of radio and TV broadcasting tower in one case, instead of GSM probe, wide band probe was used. In this case, measured electric field was 40 % of reference level for I. region of Slovenian legislation (4 % of ICNIRP reference level for general public).

In the present study, it compared the behavior of smooth muscle cells grown on various “magnesium alloys” materials. Human Smooth Muscle Cells (HSMC) were seeded (800 cells/mm^2) onto various magnesium alloy sheets, including Mg-Al-Zn alloys (AZ31, AZ91) and Mg-Al-Mn alloy (AM60). And they were cultured with SMGS (Smooth Muscle Growth Supplement) medium. Cells seeded onto tissue culture treated polystyrene dish coated with gelatin were used as controls. Forty-eight hours later, the cells were examined by immunofluorescence microscopy. In this study, it investigated three factors: vimentin, desmin, and SMC α-Actin. The results showed that the cellularity at 48 hours, all magnesium groups were much lower than controls (p<0.05), significantly. And immunoconfocal microscopy showed that vimentin, desmin, and SMC α-Actin proteins were all less in the metal groups. Therefore, it suggested that down-regulation of vimentin, desmin, and SMC α-Actin may be a common phenomenon in HSMC grown on magnesium alloys.

Collective interactions between the giant phospholipid vesicles made of POPC, cardiolipin and cholesterol after the addition of β2GPI may cause the coalescence of membrane buds to the mother cell. Using the discrete elastic model of the vesicle membrane mechanics it was shown that the coalescence of the buds depends on the adhesion strength and rigidity of the biomembrane.

Multiscale combination of microfluidic and structure-continual studies is used in order to construct the structure-phenomenological theory of stressed state in arbitrary gradient flows of dilute suspension in blood of rigid axially symmetric elongated particles possessing permanent magnetic moment. The obtained rheological equation is used to examine the revealed viscoelastic behaviour of the considered suspension, explore the possibility of control over its rheological properties with the use of an external magnetic field and investigate the dependence of the suspension effective viscosity on the hematocrit value of blood.

The paper presents a kinematic model of a human body and a corresponding graphic representation of the human figure in virtual reality. The model was developed in order to visualize the movements of the subject in a real-time virtual environment on a large display, which represented a virtual mirror. An optical system with active markers was used to assess the movements of the subjects. We conducted an experiment with 10 healthy adults performing a stepping-inplace test in a virtual environment by tracking the motion of a reference virtual figure, which represented the virtual instructor. Both figures, the training subject and virtual instructor, were superimposed and shown from the desired angle of view. It was our aim to study the abilities of immersion and adaptation to the reference movements through the virtual mirror. The results of this preliminary investigation include basic kinematic and temporal parameters of the stepping movements, providing quantitative evaluation and comparison of the subjects’ performance.

Impairments and activities of daily living (ADL) of patients with stroke are usually assessed by clinical scales. It is a rather subjective method. A device and a method are presented to objectively characterize movement disorders (impairment) of stroke patients. The finger-tapping and the pointing movements of 15 stroke patients were recorded and analysed with a simple, 2D, passive marker-based, clinically applicable movement analyser, PAM (Passive Marker-based Analyzer for Movements). The result of the objective assessment is compared to human ratings. Movement analysis gives valuable information also about the improvement of motor performance during rehabilitation. Based on the analysis, functional rating can be done with good resolution and accuracy; the measure of disability can also be determined. Good correlation has been found between the results of movement analysis and the Rivermead Motor Assessment. The rating scales assessing ADL functions give markedly different results.

Avascular necrosis of femoral head (AN) is a hip disorder with various risk factors, however, the underlying mechanisms are not yet understood. In order to elucidate the effect of the mechanical factors on AN we have compared a group of hips at risk for AN and a group of healthy hips with respect to biomechanical parameters: functional angle of the weight bearing area (ϑ), position of the stress pole (Θ), index of the gradient of the contact stress at the lateral border of the load bearing area (G) and peak contact hip stress (pmax). The test group representing hips at risk for AN consisted of 32 male hips contralateral to the necrotic hips while the control group consisted of 46 healthy male hips. The biomechanical parameters we computed with the HIPSTRESS method (based on measurements of geometrical parameters from standard anterior-posterior pelvic radiographs). The average values of parameters pertaining to both groups were compared by the unpaired two-sided Student t-test. The functional angle of the weight bearing area was on the average larger (more favorable) in the control group (112.9º±13.5º) than in the test group (105.0º±12.4º), the difference (7%) being statistically significant (p < 0.01). The position of the stress pole was more lateral (less favorable) in the test group (15.44º±7.23º) than in the control group (11.80º±7.58º), the difference (27%) being statistically significant (p = 0.037). The index of the hip stress gradient was higher (less favorable) in the test group (-17.23º±17.16º x 10m) than in the control group (26.05±16.85 x 10m), the difference (40%) being statistically significant (p = 0.028) while we found no statistically significant difference in the peak contact stress between the two groups. Our results indicate that a less favorable steep stress distribution over a smaller load-bearing area is a risk factor in AN.