Profile of cortisol, glycaemia, and blood parameters of American Bullfrog tadpoles Lithobates catesbeianus exposed to density and hypoxia stressors

The aim of this study was to evaluate alterations to the physiological profile (cortisol, glycaemia, and blood parameters) of Lithobates catesbeianus caused by the stressors density and hypoxia. The organisms were in the prometamorphosis stage and exposed to different tadpole densities: 1 tadpole/L (T1), 5 tadpoles/L (T2), and 10 tadpoles/L (T3) for 12 days. The blood was collected through the rupture of the caudal blood vessel and collected under normoxia (immediate collection) and hypoxia (after 15 minutes of air exposure) conditions. Cortisol levels rose on the fourth and eighth days of treatment and returned to basal levels by the end of the experiment. The stressor mechanisms tested did not affect glycaemia. White blood cells (total number of lymphocytes, neutrophils, and eosinophils) showed a significant difference at the twelfth day of the experiment when compared with the start of the experiment. We concluded that, under controlled conditions, a density of up to 10 tadpoles/L and air exposure for 15 minutes did not cause harmful physiological alterations during the experimental period. The answer to these stressors maybe was in another hormonal level (corticosterone)

Collaborative Ownership in Cross-Cultural Educational Digital Library Design

This paper details research into building a Collaborative Educational Resource Design model by investigating two contrasting Kenyan / UK design case-studies and an evaluation of end-users and designers’ perceptions of digital libraries and their usage patterns. The two case-studies compared are; case study 1 based on formal learning in an African university digital library. Case study 2 is centered on informal learning in an ongoing rural community digital library system which has a collaborative design model that is being designed, developed and reviewed within the UK and Africa. A small scale in-depth evaluation was done with 21 participants in case-study 1 but related to and with implications for the second case-study. In-depth user issues of access, ownership, control and collaboration are detailed and reviewed in relation to design implications. Adams & Blandford’s ‘information journey’ framework is used to evaluate high-level design effects on usage patterns. Digital library design support roles and cultural issues are discussed further

Prediction of Manure and Nutrient Excretion from Dairy Cattle

Accurate estimates of manure excretion are needed for planning manure storage facilities and for nutrient management. Data sets from metabolism studies conducted at several universities were compiled and evaluated for excretion of total manure, N, P, and K. Animal groups included calves weighing up to 204kg, heifers weighing between 274 and 613kg, nonlactating cows, and lactating cows. Regression equations were developed to predict excretion of total manure, total dry matter, N, P, and K. Predictors used in the regression equations for lactating cows included milk yield, percentages of protein and fat in milk, dietary concentrations of crude protein and neutral detergent fiber, and intakes of nutrients. The regression equations provide improved predictions of excretion and enable more accurate planning of manure storage and nutrients to be managed at the farm level

Translational Symmetries in the Linear-Chain Semiconductors K\u3csub\u3e4\u3c/sub\u3e[Pt\u3csub\u3e2\u3c/sub\u3e(P\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e5\u3c/sub\u3eH\u3csub\u3e2\u3c/sub\u3e)\u3csub\u3e4\u3c/sub\u3eX]•nH\u3csub\u3e2\u3c/sub\u3eO (X = Cl, Br, I)

The solid-state structures of the linear-chain semiconductors K4[Pt2(P2O5H2)4X]•nH2O (X = Cl, Br, I), abbreviated Pt2Cl, Pt2Br, and Pt2I, have been studied. The X-ray crystal structures of Pt2Cl at 300 and 22 K and of Pt2Br at 19 K are reported. These structures show that Pt2Cl is a composite of alternating units of Pt2 and Pt2Cl2 with (AABCCB)n translational symmetry. The X-ray structure of Pt2Br, on the other hand, shows equivalent Pt-Pt bonds and two slightly different Pt-Br bonds. Raman data confirm the composite Pt2/Pt2Cl2 structure for Pt2Cl and indicate that the Pt2Br species is comprised of dimeric units with nearly equal Pt-Pt bonds. The Pt2Br structure is viewed as involving a slight distortion from idealized (AAB)n toward (AABCCB)n translational symmetry. Structural studies of Pt2I were attempted; however, all crystals were twinned. Magnetic susceptibility, microwave conductivity, ESCA, and reflectance spectroscopy measurements are reported for Pt2Br; the material is a semiconductor, with a = 10-3Ω-1 cm-1 at 300 K, a bandgap of 0.08 eV, and a bandwidth greater than 0.05 eV. © 1988, American Chemical Society. All rights reserved