Search results for "Electric impedance"
showing 10 items of 90 documents
Novel technologies to detect atelectotrauma in the injured lung
2010
ABSTRACTCyclical recruitment and derecruitment of lung parenchyma (R/D) remains a serious problem in ALI/ARDS patients, defined as atelectotrauma. Detection of cyclical R/D to titrate the optimal respiratory settings is of high clinical importance. Image-based technologies that are capable of detecting changes of lung ventilation within a respiratory cycle include dynamic computed tomography (dCT), synchrotron radiation computed tomography (SRCT), and electrical impedance tomography (EIT). Time-dependent intra-arterial oxygen tension monitoring represents an alternative approach to detect cyclical R/D, as cyclical R/D can result in oscillations of PaO2 within a respiratory cycle. Continuous…
Evaluation of Esophageal Motility Using Multichannel Intraluminal Impedance in Healthy Children and With Gastroesophageal Reflux
2010
Abstract OBJECTIVE: : Multichannel intraluminal impedance (MII) directly evaluates esophageal bolus transport. There is a good correlation between MII and manometry in healthy adults, but there are no reports concerning children.The aim of the present study was to determine normal values of esophageal motility using only impedance measurements in healthy children and in a pediatric population with gastroesophageal reflux (GER). PATIENTS AND METHODS: : We described in the present study 60 children submitted to pH-MII for 24 hours for suspected GER. Patients were divided into 2 different groups on the basis of their pH-MII report. Group 1 patients showed acid GER, whereas group 2 patients had…
Cytotoxicity of Metal and Semiconductor Nanoparticles Indicated by Cellular Micromotility
2009
In the growing field of nanotechnology, there is an urgent need to sensitively determine the toxicity of nanoparticles since many technical and medical applications are based on controlled exposure to particles, that is, as contrast agents or for drug delivery. Before the in vivo implementation, in vitro cell experiments are required to achieve a detailed knowledge of toxicity and biodegradation as a function of the nanoparticles' physical and chemical properties. In this study, we show that the micromotility of animal cells as monitored by electrical cell-substrate impedance analysis (ECIS) is highly suitable to quantify in vitro cytotoxicity of semiconductor quantum dots and gold nanorods…
Telomere Length and Frailty: The Helsinki Birth Cohort Study
2018
Objectives: Telomere length is associated with aging-related pathologies. Although the association between telomere length and frailty has been studied previously, only a few studies assessing longitudinal changes in telomere length and frailty exist. Design: Longitudinal cohort study. Setting and participants: A subpopulation of the Helsinki Birth Cohort Study consisting of 1078 older adults aged 67 to 79 years born in Helsinki, Finland, between 1934 and 1944. Measures: Relative leukocyte telomere length (LTL) was measured using quantitative real-time polymerase chain reaction at the average ages of 61 and 71 years, and at the latter the participants were assessed for frailty according to …
Negative differential resistance in carbon nanotube field-effect transistors with patterned gate oxide.
2010
We demonstrate controllable and gate-tunable negative differential resistance in carbon nanotube field-effect transistors, at room temperature and at 4.2 K. This is achieved by effectively creating quantum dots along the carbon nanotube channel by patterning the underlying, high-kappa gate oxide. The negative differential resistance feature can be modulated by both the gate and the drain-source voltage, which leads to more than 20% change of the current peak-to-valley ratio. Our approach is fully scalable and opens up a possibility for a new class of nanoscale electronic devices using negative differential resistance in their operation.
Validation of two portable bioelectrical impedance analyses for the assessment of body composition in school age children
2017
Background Bioelectrical impedance analysis (BIA) is a convenient and child-friendly method for longitudinal analysis of changes in body composition. However, most validation studies of BIA have been performed on adult Caucasians. The present cross-sectional study investigated the validity of two portable BIA devices, the Inbody 230 (BIA8MF) and the Tanita BC-418 (BIA8SF), in healthy Taiwanese children. Methods Children aged 7–12 years (72 boys and 78 girls) were recruited. Body composition was measured by the BIA8SF and the BIA8MF. Dual X-ray absorptiometry (DXA) was used as the reference method. Results There were strong linear correlations in body composition measurements between the BIA…
Theoretical and experimental study of the role of cell-cell dipole interaction in dielectrophoretic devices: application to polynomial electrodes
2013
BACKGROUND: We aimed to investigate the effect of cell-cell dipole interactions in the equilibrium distributions in dielectrophoretic devices. METHODS: We used a three dimensional coupled Monte Carlo-Poisson method to theoretically study the final distribution of a system of uncharged polarizable particles suspended in a static liquid medium under the action of an oscillating non-uniform electric field generated by polynomial electrodes. The simulated distributions have been compared with experimental ones observed in the case of MDA-MB-231 cells in the same operating conditions. RESULTS: The real and simulated distributions are consistent. In both cases the cells distribution near the elec…
Physical fitness development in relation to changes in body composition and physical activity in adolescence
2020
The decline in adolescents’ physical fitness (PF) in recent decades has raised concerns about current population’s possible future challenges with health and physical functional capacity. This study explored the associations between body composition, physical activity, maturation, and PF development in adolescents. Furthermore, PF development of adolescents with low initial PF was assessed. A 2‐year observational study was conducted between spring 2013 and 2015. Nine comprehensive schools and their 10‐ to 13‐year‐old students were invited to participate in the study (1778), and a total of 971 students (54.6%) agreed. Cardiorespiratory fitness (20‐metre shuttle run), muscular fitness (push‐u…
A Non-Invasive Thermal Drift Compensation Technique Applied to a Spin-Valve Magnetoresistive Current Sensor
2011
A compensation method for the sensitivity drift of a magnetoresistive (MR) Wheatstone bridge current sensor is proposed. The technique was carried out by placing a ruthenium temperature sensor and the MR sensor to be compensated inside a generalized impedance converter circuit (GIC). No internal modification of the sensor bridge arms is required so that the circuit is capable of compensating practical industrial sensors. The method is based on the temperature modulation of the current supplied to the bridge, which improves previous solutions based on constant current compensation. Experimental results are shown using a microfabricated spin-valve MR current sensor. The temperature compensati…
Investigation of lattice dynamical and dielectric properties of MgO under high pressure by means of mid- and far-infrared spectroscopy.
2013
We investigate the lattice dynamical and dielectric properties of MgO single crystals and powders by measurements in the mid- and far-infrared frequency region under high pressures, ranging up to 21.7 GPa. The shift of the restrahlen region is used to determine the pressure dependence of the transverse and longitudinal optical modes. The analysis of the refractive index in the mid- and far-infrared region allowed us to obtain the pressure behavior of the static and electronic dielectric constants. The transverse effective charge slowly decreases under high pressure, reflecting the stability of MgO. As a consequence, the pressure dependence of the static and electronic dielectric constants i…