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Oliver Pabst

three times for different frequencies (0.005 Hz, 0.05 Hz and 0.5 Hz) in randomized order. The time between runs during which no voltage was applied was 4 seconds. Instrumentation A custom-built measurement system (see Fig. 1c top) was used for the recordings. A data acquisition card (DAQ) (type USB-6356 from National instruments) enabled the application of two constant voltages and simultaneous reading (both was performed with 500 samples per period). The DAQ was connected to a personal computer and controlled by a custom-made software, which was written in NI

Open access

Carles Aliau-Bonet and Ramon Pallas-Areny

measurements, either bipolar with direct contact [ 13 ] or capacitive electrodes [ 16 ], or tetrapolar [ 10 ] warrant the interest of its measurement. Measurement method In a scenario where bipolar impedances are measured on the human body, we propose to estimate the capacitance from the body to ground by connecting a known capacitor between each electrode and the impedance analyzer. Figure 2 shows the resulting equivalent circuit. If the capacitance of the added capacitors C is small enough for its impedance to be much larger than that of the body and the

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Haval Y. Yacoob Aldosky and Suzan M. H. Shamdeen

frequencies (0.05, 2, 20, 60 and 100 kHz) for the 2-inner electrodes system. Table (2) Calculated values of admittance and measured conductivity for different frequencies by the two-inner electrode system 2-Inner Electrodes f = 0.05 kHz f = 2 kHz f = 20 kHz f = 60 kHz f = 100 kHz Admittance (μS) Conductivity (μS/cm) Admittance (μS) Conductivity (μS/cm) Admittance (μS) Conductivity (μS/cm) Admittance (μS) Conductivity (μS/cm) Admittance (μS) Conductivity (μS/cm) Distilled Water 2.91 16.20 3.77 16.20 10.38 16

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Eugen Gheorghiu

, the permittivity spectra present a clear dependency of α dispersion on the membrane potential. However, for cells with radius ~2 μm, the spectra of impedance magnitude relative to the value at 1 kHz (impedance level prior to β dispersion) reveal ( fig. 1B) very small decrements related to α dispersion, ΔZr ≤ 5×10 -3 % raising tough experimental constraints. The same challenge is related to phase variations in the α dispersion ( fig 1C) where changes Δθ ≤ 2×10 -3 degrees are emphasized. When considering suspensions of larger cells ( R 1 ~ 0.5 mm), impedance

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Natália T. Bellafronte, Marina R. Batistuti, Nathália Z. dos Santos, Héric Holland, Elen A. Romão and Paula G. Chiarello

.5 (-29 to -20) -19 1 FM (kg) 14±4 5±4.4 0.07* 0.27* 8.8+5.1 (81+202.4) 7.2 to 10 (15 to 147) -1.1 19 Normal weight subjects (n=120) Bland-Altman 95% limits of agreement Data analysed BIS SFBIA ICC r Bias a (%) b 95%CI Bias c (%) d Lower Upper R (ohm) 718±99 621±97 -0.02 -0.05 97+141 (14.6+20.6) 71 to 122 (11 to 18) -180 374 Xc (ohm) 82±9.6 63±8.9 0.04 0.13 19+12 (25.8+16.9) 16 to 21 (23 to 29) -5.3 43 PA ( ₒ ) 6.6±0.8 5

Open access

Nermin Öztürk, Esin Ozturk-Isik and Yekta Ülgen

/m 2 ) Normal 21 30.76 ± 5.51 [19.82, 43.57] NS NS Osteopenia 22 29.97 ± 6.02 [16.41, 43.42] - NS Osteoporosis 5 25.25 ± 1.33 [24.03, 27.33] - - Dominant arm Characteristic Frequency (kHz) Normal 21 51.72 ± 8.57 [39.92, 69.57] NS P < 0.005 Osteopenia 22 55.91 ± 10.01 [39.96, 75,68] - NS Osteoporosis 5 65.42 ± 12.96 [57.98, 88.30] - - Total Lumbar Spine BMD (g∙cm -2 ) Normal 21 1.048 ± 0.08 [0.934, 1.259] P < 0.001 P < 0.001 Osteopenia 22 0.855 ± 0.05 [0.784, 0

Open access

Robert F. Melendy

}^{0.5e}}\sin \pi t \right)}{{{\left( 0.5\pi \right)}^{\tanh \left( 4\pi \frac{\mu B}{kT} \right)}}\left( {{G}_{in}}\cosh \pi \text{X} \right)} - 67.9 \times 10^{-3}V}$$ Figure 1 is a plot of V m vs. t from (4b)† and demonstrates the classical action potential voltage cycle in nerve under stable equilibrium conditions [ 11 , 18 , 23 , 25 , 61 , 63 ]. VI Discussion A Inference of Ionic Current Flow In the classical Hodgkin-Huxley model, it’s well-known that the lipid bilayer of the axon membrane is modeled as a lumped-capacitance C m (F) [ 11

Open access

Noel D. Montgomery and Jack L. Lancaster

{bnd}}}+{{\text C}_{6\text{bnd}}}) \\ \end{align}$$ Where C 1 bnd = C 6 * | z ctr − z bnd | ( x ctr − x bnd ) 2 + ( y ctr − y bnd ) 2 + ( z ctr − z br $${{\text C}_{1\text{bnd}}}={{\text C}_{6}}*\frac{\left| {{\text{z}}_{\text{ctr}}}-{{\text{z}}_{\text{bnd}}} \right|}{\sqrt{{{\left( {{\text{x}}_{\text{ctr}}}-{{\text{x}}_{\text{bnd}}} \right)}^{2}}+{{\left( {{\text{y}}_{\text{ctr}}}-{{\text{y}}_{\text{bnd}}} \right)}^{2}}+\text{(} {{\text{z}}_{\text{ctr}}}-{{\text{z}}_{\text{br}}} }}$$ So the discretization of Equation (10) is: (17) C 1 ϕ 1

Open access

Subhadip Chakraborty, Chirantan Das, Rajib Saha, Avishek Das, Nirmal Kumar Bera, Dipankar Chattopadhyay, Anupam Karmakar, Dhrubajyoti Chattopadhyay and Sanatan Chattopadhyay

different sets of volume fractions of glucose in DI water. Results and Discussion Fig. 3 (a) – (c) depicts the plots of variation of impedance, capacitance and conductance with volume fraction of glucose in the DI water-glucose solution for the frequencies 1 kHz, 10 kHz and 100 kHz. The experiment has been performed within the volume fraction range of 0.1 to 0.5. It is apparent from all such plots that the variation of electrical parameters of interest exhibits a quasi-oscillatory behavior with the volume fraction of glucose in the solution, instead of showing a

Open access

B. Tsai, H. Xue, E. Birgersson, S. Ollmar and U. Birgersson

.00±0.13 20 15 - 76 US 20MHz B scanner [25] 1.02±0.21 17 16 - 50 Biopsy [26] 0.85±0.11 5 26 - 74 US 22 MHz B scanner [27] Mathematical Model We consider conservation of charge—ohmic and displacement currents—in the electrodes of the EIS probe and two layers—living epidermis and dermis—in the stripped skin as illustrated schematically in Fig. 1b and summarized in Appendix A. We further employ scaling arguments [ 10 ] to reduce the living epidermis and electrodes to boundary conditions, as illustrated in Fig. 1c , which yields a