An Emergence Trap for Aquatic Insects

Excerpt: The identification of organisms is a prerequisite to developing water quality criteria for aquatic life. Identification is necessary because differences in water quality requirements are specific and may be different for closely allied species. The taxonomy of various species, particularly those associated with the aquatic environment, is much more detailed and better known for adults than for immature instars. To facilitate correlation of adult and larval forms, a trap was needed to collect the emerging adults from the various streams

Studies on cultured Schwann cells: the induction of myelin synthesis, and the control of their proliferation by a new growth factor

We have recently described the use of immunological methods to identify and purify rat Schwann cells. In dissociated cultures of neonatal sciatic nerve, all of the cells can be identified by antigenic criteria as either Schwann cells or fibroblasts. The fibroblasts may be removed by treatment with antiserum to the Thy-1 antigen and complement. The purified Schwann cells have been used to study the regulation of the expression of myelin components, and the stimulation of Schwann cell division by a soluble growth factor. Among the components of myelin, we have concentrated on the peripheral myelin glycoprotein P_0, which constitutes 50–60% of the protein in peripheral myelin. We have studied the distribution of P_0 in vitro and in vivo by immunofluorescence, immuno-autoradiography on SDS gels, and solid-phase radioimmunoassay. Our results support the hypothesis that P_0 is induced specifically as a consequence of the interaction between the Schwann cell and the myelinated type of axon. The level of P_0 in the myelin membrane is at least 1000-fold higher than in the Schwann cell membrane. Purified Schwann cells divide very slowly in a conventional tissue culture medium. This has allowed us to purify a new growth factor from extracts of brain and pituitary, tentatively named Glial Growth Factor (GGF). The activity resides in a basic protein with a native molecular weight of 6 × 10^4 daltons and a subunit molecular weight of 3 × 10^4 daltons, which is active at levels comparable to those of epidermal growth factor. GGF is mitogenic for Schwann cells, astrocytes and muscle fibroblasts

A Synopsis of Flacourtiaceae

Flacourtiaceae are a large, mostly tropical, family containing more than 800 species. As circumscribed by Warburg and Gilg the family is rather heterogeneous and indeterminate. The most recent generic treatment, that of Hutchinson, represents a considerable improvement in our understanding of the family, yet Hutchinson\u27s Flacourtiaceae still contain a number of disparate elements. This preliminary generic treatment, based upon studies of gross morphology, wood anatomy, palynology, and phytochemistry, attempts to provide a revised framework for future studies of this diverse family. Ten tribes (Berberidopsideae, Erythrospermeae, Oncobeae, Pangieae , Homalieae, Scolopieae , Prockieae, Flacourtieae, Casearieae, Bembicieae) comprising 79 genera are recognized. The tribes Abatieae, Alzateeae, Lacistemeae, Paropsieae, and Trichostephaneae are excluded from the family, as are the genera Aphloia, Asteropeia, Lethedon (=Microsemma), and Plagiopteron. Hutchinson\u27s tribe Banareae is not recognized as a distinct taxon

The Historical Development of the Yakima-Tieton Irrigation District and its Present Effect on Life in The Area Encompassing the District

Irrigation played a very important role in the development of the Yakima Valley as we know it today. The Yakima-Tieton Irrigation District was chosen to show how an irrigation system functions and the part it plays on the lives of the plants, animals and people in its area. A brief historical study of the Tieton Division of the Yakima Project was made. The construction of the Tieton Unit was studied. A slide lecture with an accompanying tape was developed to acquaint junior high school students with the purpose, function and affects of the Yakima-Tieton Irrigation District

Effects of Storage Tank Mixing on Water Quality

Storage tanks are used by water systems to maintain pressure in the distribution system and to meet the varying water demands of the system. The design and operation of the storage tanks affect their mixing characteristics which affect the water quality. Poor mixing can lead to stratification in the tanks, which can lead to low chlorine residual causing microbial growth and nitrification. This thesis presents the results of the study of seven storage tanks used in South Dakota’s rural water systems. The tanks were chosen to represent varying height to diameter ratios, varying types of disinfectant, and to study passive mixing systems. The study used temperature data from all of the tanks and water quality data from five of the tanks. Temperature and water sampling apparatus were installed into each of the five tanks to examine the tanks’ behavior at varying heights. Hydraulic parameters including volumetric exchange, densimetric Froude number, and the dimensionless mixing parameter (Roberts et al. 2006) were examined to determine if they could predict the tanks’ mixing capabilities by comparing the actual values with theoretical values required for mixing the tank. Chlorine decay modeling was completed using the CompTank program. The model results were compared with actual data obtained during the study to determine the models capability to predict chlorine decay. The data showed that thermal stratification occurred in a few of the tanks resulting in water quality stratification and depleted chlorine residual in the upper zone of the tanks. High height-to-diameter storage tanks were more susceptible to stratification. To remediate stratification in one tank, the water system drained a large portion of the tank volume into its distribution system and refilled the tank with fresh water. A second system with a stratified tank chose to overflow the storage tank. Both methods were successful in restoring the chlorine residual. Passive mixing systems were installed in two tanks to prevent stratification. As a result of the passive mixing systems, both tanks were properly mixed, indicating that passive mixing systems can be effective in mixing storage tanks. Chorine residual measurements in two tanks throughout the study were used to develop chlorine decay coefficients used for the CompTank model. When the resulting decay coefficients were inserted into the model, the model substantially fit the chlorine decay that occurred in the upper zone of the stratified tanks

People-Environment Trade-offs in Managing Communal Rangelands of South Africa

Communal rangelands in South Africa support a range of ecosystem services including water provision, carbon sequestration and livestock production for different stakeholders. Delivering these in a sustainable and socially appropriate manner necessarily requires trade-offs to be made between the different environmental and social outcomes required. We draw on empirical fieldwork and a two-day participatory stakeholder workshop to report on the early stages of a project evaluating these trade-offs in communal rangelands of the uMzimvubu catchment in Eastern Cape Province. Our findings suggest that trade-offs will be necessary at a variety of different levels within this system. For example, a key activity within these rangelands is removal of invasive plants such as wattle (Acacia mearnsii) but the environmental gains are conflictual as although this increases water availability within the system, it potentially reduces stored carbon. Wattle removal also highlights a disconnection between people and policy. While current policy mandates complete eradication of wattle, none of the local communities involved in the research wished to see this, as most of them currently make use of the trees for a range of purposes including timber, fuelwood and even livestock feed. Furthermore, trade-offs are also required between different community members, in terms of the social outcomes rangelands can deliver for them. While men conceptualised rangelands largely in terms of maximising livestock production, women focused on the collection of natural resources such as timber, herbs and thatching grass, the latter requiring accumulation of biomass during the growing season and potentially removing areas of rangeland from grazing. Understanding the opposing goals for rangeland use that exist within and between different stakeholder groups is critical to evaluating the social and environmental trade-offs required and to reach a consensus approach to the governance and management of these systems