(n.) The standard unit in the measure of electrical resistance, being the resistance of a circuit in which a potential difference of one volt produces a current of one ampere. As defined by the International Electrical Congress in 1893, and by United States Statute, it is a resistance substantially equal to 109 units of resistance of the C.G.S. system of electro-magnetic units, and is represented by the resistance offered to an unvarying electric current by a column of mercury at the temperature of melting ice 14.4521 grams in mass, of a constant cross-sectional area, and of the length of 106.3 centimeters. As thus defined it is called the international ohm.
Example Sentences:
(1) The median impedance ranged from 1500 to 3250 ohms.
(2) In the other subject MAP decreased after 25 min from 75 to 50 mmHg (10.0 to 6.7 kPa) and HR from 82 to 60 beats.min-1 while thoracic impedance increased from 28.8 to 29.6 ohm.
(3) Specific membrane resistance was calculated as either 13,000 or 800 ohm-cm2 depending on whether input resistance was attributed to the total cell surface membrane area or to the outer surface of the sphere alone.
(4) An inductively coupled, quadruple-tuned surface coil with a 50-ohm match at all relevant frequencies was used for both excitation and receiving.
(5) At 10(-6)M amphotericin B, the DC membrane resistance fell from approximately 10(8) to approximately 10(2) ohm-cm(2), and the membranes became Cl(-)-, rather than Na(+)-selective; the permeability coefficients for hydrophilic nonelectrolytes increased in inverse relationship to solute size, and the rate of water flow during osmosis increased 30-fold.
(6) Transepithelial potential difference and resistance were 8.9 mV, retinal side positive, and 339 ohm-cm2, respectively, in chronic retinal detachments.
(7) The adrenocorticolytic agent DMBA and its liver metabolite, 7-OHM-12-MBA, were investigated with respect to their mechanism of toxicity in cultured rat adrenal cells.
(8) The strain I MDCK cells used have a transmonolayer resistance greater than 2,000 ohm .
(9) Retinal pigment epithelium (RPE)-choroid-sclera preparations from black dutch-belted rabbits were sealed in an Ussing chamber maintained at 37-39 degrees C. Typical preparations produced a spontaneous voltage (Ve) of 12.5 mV (retina side positive) and possessed an electrical resistance (R) of 350 ohm-cm2.
(10) There is only a few hundred ohms resistance between an antimony pH electrode and the reference electrode so that the voltage generated can be recorded with simple low-impedance recorders linked to microcomputers.
(11) Conductances greater than 10(-4) reciprocal ohm per square centimeter can eventually be attained without any loss of membrane stability.
(12) The advantage of this technique for analysis of synaptic inputs in comparison to the standard measurements of synaptic potentials is apparent from Ohm's law.
(13) Optically black, thin lipid membranes prepared from sheep erythrocyte lipids have a high dc resistance (R(m) congruent with 10(8) ohm-cm(2)) when the bathing solutions contain NaCl or KCl.
(14) Giga-ohm seal whole cell recording technique was used to examine ionic currents changes induced by dimethylsulfoxide (DMSO) in neuroblastoma X glioma hybrid NG 108-15 cells.
(15) The impedance of the amebic cell suspension, expressed as resistivity (in ohm-cm), was significantly greater than the test solution and increased with decreasing temperature or greater cell packing (P less than 0.01), indicating that the resistivity measurements reflected the impedance of the amebic surface membrane.
(16) For the secreting stomach, the resistance between the interstitial fluid of the pit region and the fluid on the mucosal surface was 55 ohm cm(2), determined as the change in PD per unit of applied current across stomach.
(17) A case of acute pulmonary oedema developing at 4300 metres showed an impedance value of 24-1 ohms on admission.
(18) However, the mean resistance of vaginal mucus was 44 ohms for both cycling and cystic cows.
(19) When back diffusion of H+ was induced by the passage of an electrical current of 510 mua per cm2 from the secretory (S) side of pH 2.25 to the nutrient side (N) for 30 min, the spontaneously secreting mucosae showed small decreases in PD (23.6 leads to 16.2 mv) and Isc (80 leads to 61 mua per cm2) but no significant change in R. In the burimamide-inhibited mucosae there were marked and significantly greater decreases of PD (26.8 leads to 3.4 mv), R (473 leads to 170 ohms cm2) and Isc (50 leads to 13 mua per cm2).
(20) Mean platelet aggregation was significantly lower in smokers than non-smokers (23.2 ohms vs 31.5 ohms, p less than 0.005).