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Studies in Rheoencephalography (REG)

in an in vitro study. Methods: A closed loop was created using rubber and plastic tubes filled with 0.9 % NaCl, ( fig. 2 ). The loop involved a Doppler in-line flow probe (4N) connected to an ultrasound flow meter (T201 Ultrasonic Bloodflow Meter, Transonic Systems, Ithaca, NY); a disposable pressure transducer (Argon Medical Devices, Athens, TX) connected to a Blood Pressure Analyzer (Digi-Med, Micro-Med, Louisville, KY); a peristaltic pump (Masterflex, L/S, Cole-Palmer, USA) and two stainless steel metal tubes (14 mm in length and 3 mm internal diameter) as

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Measurement of cerebral blood flow autoregulation with rheoencephalography: a comparative pig study

). Relationship between Hemorrhage and Cerebral Blood Flow Hemorrhagic shock (hypotension) is the leading cause of death in both civilian and military injuries. A patient with both a severe head injury and hypotension is four times more likely to die than a patient with a head injury alone ( Manley et al, 2001 ). Despite the brain’s well developed autoregulation ( Strandgaard, Paulson, 1984 ), its vital functions are impaired when the CBF autoregulatory reserve is exhausted by prolonged hypovolemic conditions (hemorrhage). Afferent neural input to the brain seems to be

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Analysis of impedance measurements of a suspension of microcapsules using a variable length impedance measurement cell

parallel describe the current flow in the liquid surrounding the capsules. This model is very similar to the model in Figure 7 obtained by starting from a simple parallel connection of a resistor and a capacitor. A comparison of the measured impedance and the impedance predicted from the model from Figure 8 is shown in Figure 9 . Fig. 7 The final model that modeled suspension impedance with smallest fitting error. By fitting the measured data, the electrical parameters of the elements can be obtained. Table 1 presents fitted electrical parameters for

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Evaluation of sugar yeast consumption by measuring electrical medium resistance

roughness degrees: First the electrode was polished with Diamond pasta Praxis® with a roughness of 6 um, then with Diamond pasta Praxis® with a roughness of 3 um and last with alumina powder with a roughness of 1 um. The size of the grain matches the European standards (FEPA standard 43-GB-1984; R1993) [ 8 ]. 2.4 Electrochemical Cells Two different cells were used in this work. A tripolar cell, which is composed of a working electrode (WE), an Ag/AgCl reference electrode (Re1) and an AISI 304 stainless-steel concave counter-electrode (CE) with a diameter of 85 mm

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Description of corrections on electrode polarization impedance using isopotential interface factor

indicator of quality in electrode systems. Materials and methods Probe configurations The experiments were developed with two tetrapolar electrode systems built from stainless steel (AISI 304), one with adjacent shape and other with axial concentric form. The geometric design of the adjacent probe consist of four circular electrodes of 12.7 mm in diameter, where each electrode was placed at a vertex of a square with 25 mm sides, making the separation between the electrodes 18.44 mm ( Figure 1a) . The axial concentric tetrapolar electrode system has four stainless

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Enhancing sharp features by locally relaxing regularization for reconstructed images in electrical impedance tomography

. High curvature details of process equipment affect the internal flow. Correct information about them allows better models to be developed. True reconstruction of shapes in (b), (c) and (d) is necessary and immensely useful, but EIT reconstruction of these sharp features would smoothen them due to regularization. We have addressed this issue and suggested a solution to improve the image quality, by proposing a new method to locally relax regularization based on the presence of inclusion. This method is named as DeTER – Detection of Target and Edge Refinement. DeTER

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Electrical characterization of bolus material as phantom for use in electrical impedance and computed tomography fusion imaging

(generated by the impedance spectroscope) was applied to the sample through the reference and the measuring electrode. The current, I z , flowed through the sample was measured with the measuring electrode. The measuring electrode was virtually grounded. Thus the voltage that is applied to the sample was V z and the current passing through the sample was I z , hence impedance spectrum of the tissue is calculated as follows: (1) Z = V Z I Z $$\text Z=\frac{{{\text V}_{\text Z}}}{{{I}_{\text Z}}}$$ The experimental

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Testing miniaturized electrodes for impedance measurements within the β-dispersion – a practical approach

predominantly flow around the cells [ 31 , 32 , 33 ]. Only at higher frequencies (f > 1 MHz), when the membranes are electrically shortened, the impedance decreases due to the accessibility of the cytoplasm as current path which yields the β-dispersion. The impedance at low frequencies gives information about the cell volume fraction since isolating cell membranes decrease the current path. This however, needs either calibration with known cell densities or the knowledge of the conductivity of the extracellular electrolytes as well as the electrode geometry. More advanced

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Isoconductivity method to study adhesion of yeast cells to gold electrode

/AgCl reference electrode (Re1). An AISI 304 stainless steel concave counter-electrode (CE) 85 mm in diameter was also used ( Fig. 1 ). The WE was a solid cylinder (1.5 cm long) with only 1 cm 2 of its transversal section exposed and coated with gold; the rest was insulated with Grilon. The CE was made with a larger area than the working electrode to minimize its impedance. Fig.1 Three-electrode cell. WE: working electrode, Re1: reference electrode, CE: counter-electrode. 2.2 Measurement System Electrochemical measurements were performed which a Solartron 12508

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Transient bioimpedance monitoring of mechanotransduction in artificial tissue during indentation

and contains the inlet and outlet holes and the microchannels through which S-DMEM (Dulbecco’s Modified Eagle’s Medium (DMEM) supplemented with 10 % (v/v) foetal bovine serum (FBS, PAA, Germany)) flows, which nourishes and so maintains the viability of the artificial skin. The microchannels also incorporate a 20x20 mm section which encloses an array of 50 μm diameter micropillars (see Fig. 2 ) which support a polycarbonate nanoporous membrane permitting the medium to diffuse through to the skin whilst also providing a platform to support the impedance sensor. The

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