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A study was conducted to compare the precision and accuracy of the phenate method and the salicylate method for determining total ammonia nitrogen concentration in water over a wide range of salinities. The two methods provided results that were highly correlated ( P < 0.01) as follows: freshwater, n = 29, r = 0.996; low salinity (≫4 ppt), n = 17, r = 0.994; high salinity (≫24 ppt), n = 11, r = 0.981. Considering all samples the regression equation for the two methods was Y = 0.939 X + 0.0038 where X = salicylate method (mg/L) and Y = phenate method (mg/L); the r value was 0.984 ( P < 0.01), the slope differed from 1.0 ( P < 0.05), but the intercept was not different from 0.0 ( P > 0.05). In replicate analyses of the same samples, the salicylate method often gave a higher mean concentration of total ammonia nitrogen than was obtained with the phenate method. Also, precision was usually better for the salicylate method. Accuracy, as determined by spike recovery, was slightly superior for the salicylate method. The findings suggest that the salicylate method is a preferable alternative to the phenate methods for use in freshwater and saline water aquaculture applications. [ABSTRACT FROM AUTHOR]

We have applied enzyme kinetic analysis to electrophysiological steady-state data of Zhou et al. (Zhou, J.J., Trueman, L.J., Boorer, K.J., Theodoulou, F.L., Forde, B.G., Miller, A.J. 2000. A high-affinity fungal nitrate carrier with two transport mechanisms. J. Biol. Chem. 275:39894-9) and to new current-voltage-time records from Xenopus oocytes with functionally expressed NrtA (crnA) 2H+-NO3- symporter from Emericella (Aspergillus) nidulans. Zhou et al. stressed two Michaelis-Menten (MM) mechanisms to mediate the observed nitrate-induced currents, I(NO3-). We show that a single straightforward reaction cycle describes the data well, pointing out that during exposure to external substrate, S = (2H+ + NO3-)o, the product concentration inside, [P] = [H+]i(2) x [NO3-]i, may rise substantially near the plasma membrane, violating the condition [P] << [S] for MM kinetics. Here, [P] and its changes during experimentation are treated explicitly. K(1/2) approximately 20 microM for I(NO3-) at pHo from Zhou et al. is confirmed. According to our analysis, NrtA operates between about 0.2 and 0.6 of the electrical distance in the membrane (outside 0, inside 1). In absence of thermodynamic gradients, the predominant orientation of the binding site(s) is probably inwards. The activity of the enzyme is sensitive to the transmembrane voltage, V, with an apparent gating charge of +1.0 +/- 0.5 for inactivation, and transition probabilities of 0.3-1.3 s(-1) at V = 0. This gating mode impedes loss of cellular NO3- during depolarization. [ABSTRACT FROM AUTHOR]

The purpose of this exploratory study was to describe a group of African American women who smoke crack. Using aggregate data from 208 interviews with women crack smokers, we randomly selected 25 women's interview data to create the 25 life-lines. These life-lines were developed in a similar manner to the time-line analysis described by Fullilove and her colleagues (1992); we focused on events that are either extraordinarily disturbing (e.g., rape, incest, death of a child, etc.), events that are usual but often stressful (e.g., birth of a child, death of a parent, etc.), and on periods of drug use. We chose this method of analysis so as to highlight the context in which many women come to use crack cocaine. The life-lines provided a retrospective (but time-ordered) perspective and in several ways provided preliminary support for a stress-diathesis perspective. [ABSTRACT FROM AUTHOR]

Ophiomorpha irregulaire is a surprisingly poorly characterised ichnotaxon given its common occurrence in hydrocarbon reservoir facies. Current debate surrounds the ichnotaxobases suitable for ichnospecific-level identification and also the palaeogeographic distribution of the taxon. O. irregulaire is conventionally characterised in core by the presence of “spikey”, fine-grained, wall-lining pellets, since the horizontal “meander maze” that is also part of the ichnospecific diagnosis cannot normally be demonstrated. To resolve ichnotaxonomic issues concerning the validity of pellet morphology as a primary ichnotaxobase, material from the type locality is re-described (Cretaceous Book Cliffs, Utah), with an emphasis on burrow wall morphology. Comparative neoichnological studies using the callianassid crustacean Neotrypaea californiensis were additionally conducted to understand the behaviour of modern taxa that produce burrows closely resembling O. irregulaire . High-resolution, three-dimensional morphological models were created from specimens of Ophiomorpha from the type locality of O. irregulaire in Utah, USA, and from Eocene deep marine turbidites of the Juncal Formation, California. Comparison of the morphological features from these two localities, as well as specimens observed in core from offshore Newfoundland, demonstrate conclusively that O. irregulaire is not restricted to the Cretaceous Western Interior Seaway. O. irregulaire may have a stratigraphic range from Jurassic to Recent, and occur in palaeoenvironmental settings ranging from shallow marine to continental slope settings. The flame-like pellet morphology is considered characteristic of the type material, and is a valid criterion for identifying O. irregulaire in core. [ABSTRACT FROM AUTHOR]

Focuses on a study which described the occurrence of sexual abuse and the comorbidity of depression and eating disorders among African American women using crack cocaine. Brief information on the eligibility for participation on the study; Similarity between the treatment and nontreatment groups; Association between sexual abuse and presence of eating disorders; Methods and results.