Hydrological factors influencing sediment concentration fluctuations in small drainage basins

Although sediment concentrations measured in two contrasting streams in East Yorkshire fluctuate in response to similar hydrological factors, the effectiveness of these factors reflects the environmental characteristics of the drainage basins. Consequently, regression relationships used to predict sediment concentrations in individual streams are not directly applicable outside the region in which they were developed. The sensitivity of sediment concentration variations to environmental conditions makes long term estimates of denudation of limited value

Chemical Time Bombs: Linkages to Scenarios of Socioeconomic Development (CTB Basic Document 2)

The definition of a chemical time bomb (CTB), as provided in the first document of this series is "a concept that refers to a chain of events resulting in the delayed and sudden occurrence of harmful effects due to the mobilization of chemicals stored in soils and sediments in response to slow alterations of the environment." The theme of this second report was conceived at a workshop in the Netherlands in 1990. It was decided that chemical time bombs must be understood not only in terms of how they are triggered in the environment, but also in terms of the anthropogenic activities that are linked to the triggers. For example, a change in redox potential is a CTB trigger, and activities such as draining of wetlands an implementing sewage treatment have a major influence on redox potential. Thus, this report attempts to connect specific human activities to environmental disturbances that can stimulate CTNB phenomena. These connections are made for a range of activities, and matrices linking activities to effects are presented. The analysis is taken a step further by constructing scenarios, of land-use changes for example, and assessing their impacts with respect to CTBs. Thus, scenarios are used here not as a way of predicting the future, but rather for the purpose of presenting possible alternatives against which the risk of CTB events can be assessed. This publication is the second in a series of IIASA publications on Chemical Time Bombs. The first, entitled "Chemical Time Bombs: Definition, Concepts, and Examples," was published in 1991. The next publication in the series will discuss CTBs in landfills and contaminated lands

Erosionabilidad del suelo a lo largo del gradiente climático Coll de Rates - Benidorm, Alicante

[Resumen] Se estudia la influencia del clima sobre la erosionabilidad de los suelos mediante la cuantificación de la estabilidad de los agregados por medio del test de Emerson, por impactos de gotas (CNO y TOI) y por ultrasonidos (UD) a lo largo del gradiente climático Coll de Rates-Benidorm. En todos los suelos estudiados la estabilidad de los agregados es muy elevada, lo que hace difícil encontrar diferencias apreciables entre zonas de estudio. Las distintas historias de uso del suelo (incendios, pastoreo, explotación de la biomasa, etc.) ha dado lugar a la inexistencia de la influencia del clima sobre la erosionabilidad de los suelos.[Abstract] The influence of climate on soil erodibility is studied by means of aggregate stability measurements with the Emerson, drop impacts· (CNO y TOI) and ultrasound (UD) tests along the Coll de Rates-Benidorm climatological gradient. The soils have a very high aggregate stability, and this is the reason why there are not clear differences between study zones. The different past land uses (forest fire, grazing, wood exploitation, etc./) have induced the non existence of the influence of climate on soil erodibility

A phenomenological study of infertility : the couple\u27s perspective

The purpose of this phenomenological study was to describe and interpret the experience of infertility from the perspective of infertile couples, in order to gain an in-depth understanding of how it affects their lives. Ten to twenty per cent of the global population share the experience of infertility, however, little is known of their experiences and perceptions related to infertility. Literature to date mainly focuses on the physiological effects of infertility and does not take into account the context in which the experience takes place, or the meanings that people assign to this experience. To be effective, health carers need to understand the perspective of those experiencing the phenomena in order to provide appropriate information and care. A phenomenological approach was adopted for the study. A purposive sample of six couples was selected for interview. Data were generated from taped interviews and the researcher\u27s observational field notes. Data analysis was in accordance with the procedure outlined by Colaizzi (1978), which is to describe, interpret, and extrapolate common themes and meanings from the data. Interview responses were categorised by examining the participants\u27 transcripts, and identifying significant statements and meanings. Themes which emerged from the statements were then identified, and cross-case comparisons were made to confirm or modify these themes

Ultrasonic study of the gelation of gelatin: phase diagram, hysteresis and kinetics

We map the ultrasonic (8 MHz) speed and attenuation of edible-grade gelatin in water, exploring the key dependencies on temperature, concentration and time. The ultrasonic signatures of the sol-gel transition, confirmed by rheological measurements, and incomplete gel formation at low concentrations, enable a phase diagram of the system to be constructed. Sensitivity is also demonstrated to the kinetics of gel formation and melting, and associated hysteresis effects upon cyclic temperature sweeps. Furthermore, simple acoustic models of the sol and gel state enable estimation of the speed of sound and compressibility of gelatin. Our results demonstrate the potential of ultrasonic measurements to characterise the structure and visco-elasticity of gelatin hydrogels.Comment: 15 pages, 8 figure

Breast self examination: a healthy approach: teaching manual

The theme of this health teaching package is breast care with an emphasis on step-by-step instruction f0r breast self examination. The package has been designed to guide health professionals in the facilitation of workshops and discussion groups promoting breast care for women. Materials included in the manual may be adapted to suit audience requirements..