Statistical comparison of the triangle test and the two-of-five test for taste and odor evaluation

The Triangle test and 2-of-5 test are compared for their ability to evaluate tastes and odors in water and wastewater utilities. Both tests have varying statistical sensitivities. The 2-of-5 test is more sensitive and more powerful than the Triangle test, and generally requires fewer panelists for the same level of statistical confidence. This paper presents a method for determining the number of panelists for either test, and compares the results.

Fate and transport of copper-based crop protectants in plasticulture runoff and the impact of sedimentation as a best management practice

The fate and distribution of copper-based crop protectants, applied to plasticulture tomato fields to protect against disease, were investigated in a greenhouse-scale simulation of farming conditions in a coastal environment. Following rainfall, 99% of the applied copper was found to remain on the fields sorbed to the soil and plants; most of the soil-bound copper was found sorbed to the top 2.5 cm of soil between the plasticulture rows. Of the copper leaving the agricultural fields, 82% was found in the runoff with the majority, 74%. sorbed to the suspended solids. The remaining copper, 18%, leached through the soil and entered the groundwater with 10% in the dissolved phase and 8% sorbed to suspended solids. Although only 1% copper was found to leave the field, this was sufficient to cause high copper concentrations (average 2102+/-433 microg/L total copper and 189+/-139 microg/L dissolved copper) in the runoff. Copper concentrations in groundwater samples were also high (average 312+/-198 microg/L total copper and 216+/-99 microg/L dissolved copper). Sedimentation, a best management practice for reducing copper loadings. was found to reduce the total copper concentrations in runoff by 90% to a concentration of 245+/-127 microg/L; however, dissolved copper concentrations remained stable, averaging 139+/-55 microg/L. Total copper concentrations were significantly reduced by the effective removal of suspended solids with sorbed copper.

Views of Earth's magnetosphere with the image satellite

The IMAGE spacecraft uses photon and neutral atom imaging and radio sounding techniques to provide global images of Earth's inner magnetosphere and upper atmosphere. Auroral imaging at ultraviolet wavelengths shows that the proton aurora is displaced equatorward with respect to the electron aurora and that discrete auroral forms at higher latitudes are caused almost completely by electrons. Energetic neutral atom imaging of ions injected into the inner magnetosphere during magnetospheric disturbances shows a strong energy-dependent drift that leads to the formation of the ring current by ions in the several tens of kiloelectron volts energy range. Ultraviolet imaging of the plasmasphere has revealed two unexpected features-a premidnight trough region and a dayside shoulder region-and has confirmed the 30-year-old theory of the formation of a plasma tail extending from the duskside plasmasphere toward the magnetopause.

Timing and magnitude of response of plasma aldosterone concentration to bolus adrenocorticotropin: importance of sodium balance in outpatient testing

Plasma aldosterone concentration (PAC) response to ACTH is utilized in clinical and experimental protocols. However, PAC response to ACTH in normal subjects controlled for modifiers of PAC has not been established. Our report includes two experiments. In both, subjects were studied in the morning and were in sodium (Na+) balance prior to study on 4 g Na+ for phase I, and 2 and 8 g Na+ diets for phase II. Na+ balance was established by 24-h urinary Na+ (UNa+) in phases I and II, and also by fractional excretion of Na+ (FENa+) in phase II. After being supine for 60 min, subjects received 0.25 mg of iv bolus ACTH. PAC, plasma renin activity and plasma potassium (K+) were drawn every 30 min in phase I and every 15 min in phase II. The rise in PAC (rPAC) and correlation coefficients were calculated. In phase I, peak PAC occurred at 30 min, 1130 +/- 420 pmol/L, with a rPAC of 810 +/- 310 pmol/L. Twenty-four hour UNa+ was 86 +/- 45 mmol/24 h. In phase II, time and magnitude of peak PAC and rPAC were dependent on diet. Both occurred at 30 min for 8 g Na+: peak PAC was 640 +/- 210 pmol/L and rPAC was 440 +/- 190 pmol/L; and at 60 min for 2 g Na+: peak PAC was 1040 +/- 320 pmol/L and rPAC was 690 +/- 220 pmol/L. Correlation coefficients for rPAC and 24-h UNa+ was r = -0.44, P less than 0.05 and for rPAC and FENa+ was r = -0.46, P less than 0.05. In summary, in subjects supine for 60 min prior to iv bolus ACTH, Na+ balance is the most important determinant of PAC response. Both magnitude and timing of rPAC is influenced by Na+ balance. Finally, both 24-h UNa+ and FENa+ are valid for establishing pretesting Na+ status.

Plasma free thyroxine concentrations in patients receiving levothyroxine for thyroid suppression

The usual recommendation is to follow total triiodothyronine (T3) concentration during levothyroxine (L-thyroxine) therapy because 65% of clinically euthyroid patients receiving L-thyroxine have normal T3 but elevated total thyroxine (T4) levels. Because free thyroxine (FT4) is the metabolically active form of T4, our study was designed to determine whether FT4 by analog radioimmunoassay method is normal or increased in euthyroid patients receiving L-thyroxine. Twenty-seven clinically euthyroid patients, 5 males and 22 females, receiving L-thyroxine for thyroid suppression, were studied in a prospective protocol. Twenty-one euthyroid patients not receiving L-thyroxine served as controls. Samples were analyzed for T4, T3, T3 (RU), TSH, and FT4 by three analog methods. Mean FT4 levels were greater than control for all three assays. The percentage of patients with FT4 in the hyperthyroid range was 63% for assay I, 41% for assay II, and 52% for assay III. When patients were grouped by dose of L-thyroxine, FT4 levels were not significantly increased. Sixty-two percent of patients receiving L-thyroxine had T4 levels in the hyperthyroid range. T3 concentrations were not significantly greater in the L-thyroxine group when compared with control. In the L-thyroxine group, thyrotropin was significantly less than in the control group. FT4 concentration by analog method is in the hyperthyroid range in as many as 63% of clinically euthyroid patients receiving L-thyroxine. The use of FT4 to assess thyroid status may cause inappropriate adjustment of L-thyroxine dose. T3 level continues to parallel closely the physician's clinical impression and best represents peripheral metabolic status.

Barium inhibition of sodium ion transport in toad bladder

The effect of Ba2+ on Na+ transport and electrical characteristics of toad bladder was determined from change produced in short circuit current (Isc), epithelial, apical and basal-lateral potentials (psit, psia, psib), epithelial and membrane resistances (Rt, Ra, Rb) and shunt resistance (Rs). Mucosal Ba2+ had no effect. Serosal Ba2+ reduced Isc, psit, psia, and psib, but had no effect on Rt, Ra, Rb and Rs. Minimal effective Ba2+ concentration was 5-10(-5) M. The phenomenon was reversed by Ba2+ removal, but not by 86 mM serosal K+. Ba2+ inhibition of Isc did not impair the response to vasopressin which was quantitatively the same as controls. Psia with Ba2+ equalled psib. After Ba2+ inhibition, ouabain produced no further decrease in psit and Isc. Ba2+ exposure after ouabain did not decrease psit and Isc. The results suggest that Ba2+ inhibits the basal-lateral electrogenic Na+ pump.