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11th Mediterranean Conference on Medical and Biomedical Engineering and Computing 2007: MEDICON 2007, 26-30 June 2007, Ljubljana, Slovenia

Tomaz Jarm ; Peter Kramar ; Anze Zupanic (eds.)

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Biomedical Engineering

Institución detectada Año de publicación Navegá Descargá Solicitá
No detectada 2007 SpringerLink


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ISBN electrónico


Editor responsable

Springer Nature

País de edición

Reino Unido

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© Springer-Verlag 2007

Cobertura temática

Tabla de contenidos

Parameter Optimization in Voltage Pulse Plethysmography

Martina Melinscak

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.

Palabras clave: Voltage Pulse; Measurement Sensitivity; Transient Process; Resistance Change; Sensitivity Curve.

Pp. 198-201

Effect of Modulated 450 MHz Microwave on HumanEEG at Different Field Power Densities

Hiie Hinrikus; R. Tomson; M. Bachmann; J. Lass; V. Tuulik

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.

- Biological Effects of Electromagnetic Radiation | Pp. 210-213

Regenerative Effects of (-)-epigallocatechin-gallate Against Hepatic Oxidative Stress Resulted by Mobile Phone Exposure

Elcin Ozgur; G. Güler; N. Seyhan

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).

- Biological Effects of Electromagnetic Radiation | Pp. 214-217

EMF Monitoring Campaign in Slovenian Communes

Blaz Valic; J. Jancar; P. Gajsek

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).

Pp. 234-237

Expression of Smooth Muscle Cells Grown on Magnesium Alloys

Shao Kuo Lu; W.H. Lee; T.Y Tian; C.H. Chen; H.I. Yeh

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.

Palabras clave: Magnesium Alloy; Wire Electrical Discharge Machine; Growth Profile; Magnesium Alloy Sheet; Metallic Sheet.

Pp. 242-245

Coalescence of phospholipid vesicles mediated by β2GPI – experiment and modelling

Jasna Urbanija; B. Rozman; A. Iglič; T. Mareš; M. Daniel; Veronika Kralj-Iglic

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.

Palabras clave: Adhesion Energy; Phospholipid Vesicle; POPC Vesicle; Unilamellar Phospholipid Vesicle; IFMBE Proceeding.

- Biomaterials | Pp. 246-248

Combination of microfluidic and structure-continual studies in biorheology of blood with magnetic additions

Evgeny Taran; V.A. Gryaznova; O.O. Melnyk

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.

Palabras clave: Suspended Particle; Couple Stress; Carrier Fluid; Magnetic Carrier; Simple Shear Flow.

Pp. 257-261

Virtual Rehabilitation of Lower Extremities

Tomaž Koritnik; T. Bajd; M. Munih

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.

Palabras clave: Knee Angle; Graphic Processor Unit; Posterior Superior Iliac Spine; Step Period; Stance Duration.

Pp. 262-265

Rating Stroke Patients Based on Movement Analysis

Akos Jobbagy; G. Fazekas

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.

Palabras clave: Stroke Patient; Movement Analysis; Barthel Index; Functional Independence Measure; Modify Ashworth Scale.

- Biomechanics | Pp. 266-269

Hip stress distribution may be a risk factor for avascular necrosis of femoral head

Veronika Kralj-Iglic; D. Dolinar; M. Ivanovski; I. List; M. Daniel; B. Mavcic; M. Tomsic; A. Iglic; Veronika Kralj-Iglic

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.

- Biomechanics | Pp. 282-285