Influence Of Biological Factors Research Articles

A Planning and control system for the small firm: A development of operations research application in agriculture

This article reviews the use of operations research techniques in agriculture and suggests the methods available have not been fully exploited due to both the strong influences of biological factors on the farm business and the variety of tasks that the manager has to perform. There would appear to be a requirement for a simple system of business control which provides a rapid analysis of farm data without involving the manager in excessive time-consuming recording. A pig enterprise simulation model has been developed which can be combined with data from pig herds to provide a forecast of individual herd performance. This model could be used as the basis of a national or regional budgetary control scheme to provide farm managers with regular and current budgetary control information at relatively low cost.

Taper Functions and their Application in Forest Inventory

Total inventories and methods of volume summary which facilitate compilation of tree and log volumes to any desired standard of utilization are needed. It should be possible to find volume per tree to any specified standard of utilization expressed as stump height, top dib, and/or section height. Furthermore, the technique should be able to provide the fraction of volume per tree located in logs of any specified length and dib and by any system of scaling, be it board feet, cubic feet, or weight. The system also should be usable to describe the influence of biological factors on bole shape and taper, and to estimate component weights in biomass and other studies. The functions developed in this paper and based upon dbh, total height, and section height as a fraction of total height can meet most of these requirements.

Effect of Certain Soil Organisms on the Eggs of Parasitic Roundworms

THE influence of biological factors on the development and viability of eggs of parasitic roundworms (geo-helminths) in soil has not yet been sufficiently explored. It is known that some fungi are able to attack free-living Nemathelminths1–3. It has also been shown that some fungi can attack larvae of Strongyloides from horses and larvae of Trichostrongylides from cattle3. Some fungi are also capable of inhibiting the development of eggs of ascarids in vitro4. Gudzhabidze and Preobrazhenskaya5 performed experiments on Ascaris eggs by influencing them with micro-organisms, which had been isolated from the soil specimens from sewage farms. Certain species of actinomycetes and soil bacteria were capable of exerting a depressing effect on the eggs of ascarids.

Dependence of X-Ray Sensitivity of Yeast on Phase State and Anoxia

Most investigations on the modification of radiation damage in microorganisms have been primarily if not entirely concerned with primary physicochemical processes (i.e., modification of quality and quantity of free radical production), and it has not been necessary to consider the influence of biological factors in explaining the modification of X-ray sensitivity by such treatments as anoxia (1-3), phase state changes (4-6), and addition of various chemicals (7). In this investigation the influence of two modifying factors, anoxia and phase state change (liquid state versus frozen state), used both singly and together, on two closely related strains of haploid yeasts has been studied. If only physical processes concerned with the formation of free radicals are involved, the dose modifying factors2 (DMFs) for these two strains should be identical. Beam has found that the same degree of protection is afforded by anoxic conditions for a haploid yeast and its related diploid and tetraploid strains (2). The two strains of haploid yeast studied here, however, have quite different DMFs for the two modifying agents used, and hence a broader interpretation of the migration model must be invoked.

Studies of cuticular lipides of arthropods. I. The influence of biological factors on the composition of the wax from Ceroplastes destructor

This chapter discusses the chemistry and biochemistry of the test or cover of female scale insects, with special reference to soft scales, Coccidae. In the case of soft scales, waxy materials are an important component of the cover. However, in the case of Ceroplastes spp., particular aqueous components of the test referred to as “interior honeydew” are also important constituents, in addition to the waxy materials. Although true wax, esters of higher aliphatic fatty acids and higher aliphatic alcohols, are the major components of the waxy fraction, cyclic waxes are unique components in the test of Ceroplastes spp. Except for sugars and amino acids in the interior honeydew, almost all the components seem to be biogenic products of the scale insects themselves. Production and secretion of the bulky cover by soft scales are in contrast to the thin, hard cover of armored scale insects. Although there is little information on the chemical properties of non-lipid materials in the test covers of armored scales, the covers of both soft scales and armored scales apparently play an important role in the protection of the insect's body from deleterious environmental factors and natural enemies.

Influence of Biologic Factors in Retention of Artificial Dentures*

Influence of Biologic Factors in Retention of Artificial Dentures*