Library

Notes: We present a new method of characterizing the void structures of soils from water retention curves as the primary source of data. The method avoids the problems of other current approaches, which use smoothing curves and can miss the subtleties of soil structure, and usually ignore the shielding of large pores by the small connecting throats surrounding them. In the new method, software we have named ‘Pore-Cor’ is used to generate simple three-dimensional networks of voids that have the same water retention characteristics and porosities as the soils. To find the geometry of the required networks, we have introduced a Boltzmann-annealed simplex which works in four parametric and three Boolean dimensions of parameter space. Also, a more robust measure of the difference between the experimental and simulated water retention curves has been developed. The method is applied to water retention curves for a wide range of English and Welsh soils, both experimental and generated from a pedotransfer function. The resulting simulated void structures have void sizes that change as expected across the soil texture diagram, have different structures as highlighted by the locations of retained water, but have connectivities (number of connecting throats per pore) that vary little. A wide range of other calculations of wetting and non-wetting fluid transport properties, and calculations of the behaviour of fluid-borne pollutants, are now possible. The main bar to further progress is a lack of sufficiently accurate and comprehensive data for water retention, and for saturated and unsaturated hydraulic conductivity.

Notes: This investigation tends Co support the Clarke hypothesis that subjects from “adverse” environments arc likely to show greater cognitive growth than persons from “less adverse” homes. However, the present study indicates that increments in cognitive growth are not necessarily dependent on removal from the “adverse” environment. Explanation may involve maturation, in the form of secondary and compensatory growth, and change from school to work environments. Because of large increments in intelligence in children from “less adverse” homes leaving comprehensive schools there may be reason to suggest that school environment may play an important though at present limited role in cognitive development.

Notes: The sigmoid compressive stress-strain relationship of lye bread, pumpernickel bread and two polyurethane foams (0-75% deformation) were fitted by four empirical models having three or four parameters. No unique model was inherently superior for goodness of fit or for strain definition, that is whether it was presented as an engineering or Hencky's strain. Two models, however, one with three and the other with four parameters, were easier to interpret in terms of stress-strain relationship shape characteristics and are recommended.

Notes: Background:  Carica papaya L. is a fruit yielding tree, wildly grown or cultivated in the tropics and subtropics. Its pollen grain has been reported to be airborne and cause immunoglobulin E (IgE)-mediated hypersensitivity.Objective:  To conduct long-term aerobiological study on Carica pollen, along with aeroallergenic particles originating from it and to identify vis-à-vis characterize an important IgE-reactive component present in this pollen.Methods:  The seasonal and diurnal periodicities of airborne C. papaya pollen were recorded in a 5-year survey using a Burkard volumetric sampler. The allergenic potential was studied by skin prick tests, IgE-enzyme-linked immunosorbent assay (ELISA) and also by aeroallergen immunoblotting. The total pollen extract was fractionated by Sephacryl S-200 column, and out of the eluted five fractions, the maximum IgE-reactive fraction (as found in ELISA inhibition) was resolved into five major subfractions in reverse-phase high-performance liquid chromatography (RP-HPLC). The subfraction with optimum IgE reactivity was studied by activity gel, native and nonreducing sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). The homogeneity of the isolated protein fraction was checked by crossed immunoelectrophoresis with rabbit antisera and IgE reactivity was confirmed by ELISA inhibition and immunoblotting using individual patient sera.Results:  The Carica pollen occurred in the air round the year with peaks during January and September–October. Among a patient population of 1000, skin-test results showed 27.8% +1 level and 5.6% +2/+3 level reactions. In aeroallergen immunoblotting of exposed Burkard tape segments, the detected allergen spots showed a significant correlation with airborne pollen count recorded. The pollen extract elicited loss of IgE reactivity when treated with reducing agent-like β-mercaptoethanol and heat, but showed six IgE-reactive components in nonreducing IgE-immunoblot. The fraction 1 eluted from Sephacryl S-200 column showed highest IgE reactivity and resolved into five major components in RP-HPLC. Out of these, the fraction showing optimum IgE reactivity in IgE-ELISA inhibition and immunoblotting with patient antisera, elicited esterase activity and found to be a homogenous protein of 100 kDa.Conclusion:  Carica papaya tree contributes significantly to the aeropollen and aeroallergen load of the suburban outskirts of Calcutta metropolis, India. The pollen extract contains an important IgE-reactive protein component of 100 kDa molecular weight with esterase activity.