Mobile radio alternative systems study, executive summary

Present day mobile communication technologies, systems and equipment are described from background in evaluating the concepts generated in the study. Average propagation ranges are calculated for terrestrial installations in each of seven physiographic areas of the contiguous states to determine the number of installations that would be required for nationwide coverage. Four system concepts are defined and analyzed to determine how well terrestrial systems can fulfill the requirements at acceptable costs

Harvesting and Feeding Drought-Stressed Corn

How to best harvest, store and use drought-stressed corn is a problem dairy and livestock producers may encounter at one time or another. The severity of the drought, cultural practices, plant growth, plant maturity and livestock feeding regimes are factors that influence how to harvest, store and feed most effectively the drought-stressed corn. Dairy and livestock producers attempting to salvage usable feed from their drought-stressed fields of corn must not only be wary of poisoning their livestock, but poisoning themselves as well. Accumulation of nitrates in drought-stressed corn can cause nitrate toxicity in animals and ensiled drought-stressed corn can produce poisonous nitrogen gases during the fermentation process, which may be lethal to livestock and humans

Prussic Acid Poisoning of Livestock: Causes and Prevention

What Is Prussic Acid? Sudangrass, sorghum, and sorghum-sudangrass hybrids are among a group of plants that produce cyanide, which can poison livestock under certain conditions. Also included in this group of plants are johnsongrass, chokecherry, and black cherry. These plants produce cyanogenic glycosides during their growing stage. Glycosides are compounds containing a carbohydrate (sugar) and a noncarbohydrate residue in the same molecule. They decompose (breakdown) into glucose sugar and noncarbohydrate residue by hydrolysis (addition of water) as a result of enzymatic action. In cyanogenic plants this decomposition frees the cyanide from its chemical bond, and it becomes toxic hydrocyanic acid, frequently called prussic acid, and abbreviated HCN. The intact, still-bonded cyanide and glucose are not poisonous. But, when certain enzymes are present that break the bond and free the cyanide, prussic acid (a highly toxic poison) is formed. The enzymes involved in this chemical decomposition of the cyanide and glycosides usually are present in the same plant—but may be available from other sources. Animal digestive juices are a probable source

How efficient are seeding operations : Kondinin work study

The efficiency of machinery and labour during seeding operations was studied in 1977 by the Kondinin and Districts Farm Improvement Group and the Department of Agriculture. The aim was to find what influenced efficiency during cropping. Time spent on activities during the working day was measured, and it was found that repairs, maintenance, meals and other incidental jobs considerably reduced the time spent driving the tractor. Each farmer participating in the study was given the results of his own farm compared to the group, indicating tasks most needing improvement

Heavy metal content of vegetables irrigated with mixtures of wastewater and sewage sludge in Zimbabwe: Implications for human health

There is growing public concern in Zimbabwe over the illegal cultivation of vegetables on soils amended with sewage sludge or irrigated with admixtures of sewage and sewage sludge. Excessive accumulation of heavy metals in agricultural soils may not only result in environmental contamination, but lead to elevated heavy metal uptake by crops, which may affect food quality and safety. The work reported here studied heavy metal concentrations in crops irrigated with sewage sludge and sewage/sewage sludge admixtures at Firle Municipal Farm in Harare. The crops analysed in this study are heavily contaminated with the four regulated elements Cd, Cu, Pb and Zn. This contamination is at its highest in two of the staple dietary crops maize and tsunga. Tsunga leaves contained 3.68 mg kg-1 Cd, over 18 times the permissible level by the EU standards (0.2 mg kg-1); Cu concentrations were 111 mg kg-1, 5 times the EU Standard (20 mg kg-1); concentrations of Pb were 6.77 mg kg-1, over 22 times the permissible levels allowed by both EU standards and UK guidelines (0.3 mg kg-1); Zn concentrations were 221 mg kg-1, over 4 times the guideline value (50 mg kg-1). The other plants (beans, maize, peppers and sugarcane) also contained concentrations of heavy metals above the permissible levels. Furthermore the concentrations observed in this study were higher than those reported by other workers who have examined vegetation from other contaminated sites. This study highlights the potential risks involved in the cultivation and consumption of vegetables on plots irrigated with sewage sludge, a practice which may place at risk the health of the urban population who consume these vegetables

Nitrate Poisoning of Livestock Causes and Prevention

Nitrate poisoning is generally caused when animals eat too much forage that is high in nitrates not changed to protein in the plant. Poisoning can also happen when animals eat too much urea or nitrogen fertilizer spilled in the field or left where the animals can find it. Nitrate fertilizer is palatable, especially to cattle

Determining the Value of Drought-Stressed Corn

Drought-stressed corn for grain or silage does not automatically signal disaster, as both crops can provide high-quality forage for ruminant animals. Drought-stressed corn or corn that is unpollinated will produce little or no grain crop for the crop farmer to sell, but dairy producers can use the unpollinated corn for silage. On a dry matter basis, the drought-stressed corn will be approximately equal in feeding value to normal corn silage

A Note on the Flexural Properties of Bark Board

Bending properties of particleboards made from soft maple, red oak, white oak, black cherry, beech, and yellow-poplar bark were obtained and compared with the specimen's density and thickness. Regression analyses indicated that the bending properties depend not only on species but also on density and/or specimen thickness. This dependence was not consistent among species

The Effect of Species and Substrate Density on the Flexural Properties of Epoxy-Impregnated Barkboard

Bark from red oak, yellow-poplar, soft maple, and beech was individually mixed with 6% (by weight) powdered phenolic resin and pressed into boards having nominal densities of 40, 50, 60, and 70 lb/ft3 (0.64, 0.80, 0.96, and 1.12 g/cm3). Half of these boards were used as controls and half were impregnated with a solution of 100 parts by weight of epoxy resin, 25 parts styrene oxide, and 12.06 parts N,N-diethyl-1, 3-propanediamine. Polymer retention was found to be linearly related to the substrate density and was somewhat dependent upon the species of bark. The impregnation process resulted in dramatic changes in the flexural properties of the barkboard. Increases in MOR of 3.0- to 4.0-fold and in MOE of 2.6- and 3.6-fold were observed over control values, with the largest improvements occurring in the red oak specimens. In contrast to the control specimens, MOR and MOE values for the epoxy-impregnated specimens were not well correlated. In addition, correlations of MOR with the substrate density and polymer mass loading were generally low or varied greatly with bark species. MOE correlations were notably higher, but variable