Range Of Ratio Values Research Articles

Cyclic-ratio schedule analysis of a serotonin agonist and depletor on consummatory behaviour

Four male Wistar rats, 180 days old at the start of the experiment, at 85% of their free-feeding body weight were trained to respond on a geometric cyclic-ratio schedule comprised of the following ratio values: 2, 4, 8, 16, 32 and 64, for 0.1 ml of 5% sucrose reinforcement. The response functions (response rates plotted against reinforcement rates) were linear and of negative slope over the range of ratio values from 2 to 16. IP administration of 1.0 mg/kg 5-MeODMT reduced the x- and y-intercepts of the linear portion of the response function without altering the slope relative to 2.0 ml/kg 0.85% saline IP. This was interpreted as a perceived palatability effect. IP administration of 100 mg/kg pCPA elevated the reinforcement rate intercept but also decreased the slope of the response function. This finding was interpreted as an increase in the perceived palatability of the reinforcer, coupled with a decrease in motivation at higher schedule conditions, possibly due to peripheral effects of pCPA.

On the net transfer of carbon dioxide from liquid precipitation to the atmosphere

Most of the water‐soluble carbonate and non‐marine calcium (Ca*) in background aerosol in the northern hemisphere could originate as calcium carbonate (CaCO3) of arid soil origin. This is most relevant to the tropics, and a good portion of the temperate latitude belt. However, at equilibrium pH‐values between about 6 and 7, the dissolved carbonate is primarily present as the bicarbonate (HCO3−). Selecting a random set of precipitation samples in the same pH‐range, the HCO3−/Ca* stoichiometric ratio values were evaluated for a number of background locations in the northern hemisphere. The representative range observed is ∼ 0.04‐0.5. Assuming that acid‐base neutralization reactions are ubiquitous, the above range of ratio values suggests that aqueous precipitation at the surface ‐ or possibly some raindrops aloft ‐ in background locations affected by arid aerosol could act as a net source of carbon dioxide (CO2) to the atmosphere, and not vice versa, as has been universally assumed or implied in the past.

Relationship between saliva salicylate concentration and free or total salicylate concentration in serum of children with juvenile rheumatoid arthritis

Our purpose was to determine the feasibility of using salicylate (SA) concentrations in saliva as an indirect measure of SA concentrations in serum of children with juvenile rheumatoid arthritis. Sixty-four paired blood and saliva samples were obtained from 17 children, 4 to 17 yr of age (average, 9 yr), who were receiving aspirin every 8 hr. Serum total (free and bound) SA concentrations ranged from 5 to 36 mg/100 ml. The fraction of free (unbound) SA in serum, determined by equilibrium dialysis against an equal volume of buffer, rose with increasing total SA concentration. SA concentrations in saliva correlated strongly with both free and total SA concentrations in serum. The ratio of SA concentration in saliva to total SA concentration in serum rose with increasing total SA concentration in serum, whereas the relationship between SA concentration in saliva and free SA concentration in serum was essentially linear. However, there was considerable intrasubject variation of the saliva SA to serum free SA concentration ratio that could not be related to fluctuations of saliva pH. Therefore another analysis of the relationship was performed, using areas under the concentration–time curve during a dosing interval (AUCτ), which were determined from 0-, 2-, 4-, and 8-hr saliva SA and serum free SA concentrations of 12 children. These patients had serum SA concentrations at or near steady state and had provided all 4 pairs of blood and saliva samples during 1 dosing interval. The time-average saliva SA and serum free SA concentrations calculated from the AUCτ values are strongly correlated (r = 0.944, p < 0.001). The mean saliva SA to serum free SA concentration ratio determined from these data is 0.637. This ratio varied appreciably between patients (coefficient of variation, 24%; range of ratio values, 0.358 to 0.892), which limits the usefulness of salivary SA determinations as a noninvasive indirect method for monitoring serum free SA concentrations in children with juvenile rheumatoid arthritis. Clinical Pharmacology and Therapeutics (1980) 27, 619–627; doi:10.1038/clpt.1980.88

Wavelengths of single-layer folds; a comparison between theory and observation

The Biot theory was tested by measuring wavelengths of 818 folds from six different locations. The folds are in quartz veins and in slate and phyllite. The mean relative wavelength (4.0 to 6.8) leads to ratios of layer viscosity to medium viscosity of 2 to 8, too low for the Biot theory to apply directly. A modified Biot theory was applied, taking into account uniform shortening and thickening of the layer that accompanies the folding process. The new viscosity ratio values range from 14 to 3, and the uniform shortening and thickening ranges from 1:2.7 to 1:5.7.