Showing papers by "North Carolina State University published in 1970"

Implicit flood routing in natural channels

Abstract: Flood routing in natural channels and many other applications in hydraulic engineering based on the solution of the equations of unsteady flow require fast and accurate numerical methods. Numerical methods which are successful in other applications prove to be inefficient when used for flood routing. An implicit numerical method which is both fast and accurate can be established on the basis of: (1) a centered difference scheme to represent the primary differential equations in finite difference form; and (2) the simultaneous solution of the finite difference equations for each time step. The difference equations constitute a system of nonlinear algebraic equations which can be solved on a digital computer by Newton iteration method. The computational scheme becomes very efficient when advantage is taken of the sparseness of the matrix of coefficients of the linear systems employed in the iteration. Applications of the implicit method show that it can be conveniently used for highly irregular channels.

The measurement of emulsifying capacity by electrical resistance

Abstract: SUMMARY— A method was developed to objectively measure the emulsifying capacity (ECJ of meat and fish protein extracts by electrical resistance The method of Swift et al (1967) was modified to deliver oil at a constinuous rate at the point of blender agitation, thus forming an emulsion for testing the validity of the electrical resistance method This modification reduced the variance of the end-point determination within samples The precision of end-point determinations by electrical resistance was equivalent to the modified visual method, and had the advantages of being objective, having a finite end-point and providing a continuous record of the emulsion during formation and collapse The EC of fresh muscle slurry extracts from fish were higher than those from beef and pork However, the EC of fresh muscle supernatant extracts ranked from highest to lowest are beef, fish and pork, respectively In all cases, the EC of supernatant and fresh muscle extracts was higher than the slurry and frozen muscle extracts, respectively

Mechanisms of adsorption of s-triazines by clay colloids and factors affecting plant availability.

Abstract: Many new organic agricultural chemicals have been developed which offer great potential in the production and preservation of food and fiber (Weber 1969). In the process of developing and utilizing these chemicals we must come to understand how they affect the target organisms and what becomes of them after they have done their job. The purpose of this review is to discuss1 the behavior of one family of these organic compounds, the s-triazines, at the molecular level, in systems in which the chemicals are associated with clay minerals. Factors affecting the adsorption and release of s-triazines by clay colloids and the availability of the compounds to plant roots will also be included. The literature citations are limited to those studies in which s-triazines and clays were directly associated and situations in which other compounds behaved in a manner similar to the s-triazines.

A Decision Theoretic Approach to Crop Disease Prediction and Control

Abstract: The pesticide application practices of California peach growers in controlling peach brown‐rot are used to demonstrate how Bayesian decision theory procedures can be used to arrive at optimal crop disease control practices. Subjective probabilities of disease loss intensity are measured and used in the decision model. Information from an analyst (this researcher) is combined with farmers' subjective probabilities of disease loss by means of Bayes' theorem. Optimal pesticide use actions are computed for three different objective functions—maximum subjective expected returns, mean‐standard deviation of returns, and maximum expected returns with a minimum income side condition.

A probabilistic formulation and statistical analysis of guttman scaling

Abstract: By proposing that the latent or true nature of subjects is identified with a limited number of response patterns (the Guttman scale patterns), the probability of an observed response pattern can be written as the sum of products of the probability of the true type multiplied by the chance of sufficient response error to cause the observed pattern to appear. This model contains the proportions of the true types as parameters plus some misclassification probabilities as parameters. Maximum likelihood methods are used to make estimates and test the fit for some examples.

The Cultural Basis for Our Environmental Crisis

Abstract: The forces of democracy, technology, urbanization, increasing individual wealth, and an aggressive attitude toward nature seem to be directly related to the environmental crisis now being confronted in the Western world. The Judeo-Christian tradition has probably influenced the character of each of these forces. However, to isolate religious tradition as a cultural component and to contend that it is the "historical root of our ecological crisis" is a bold affirmation for which there is little historical or scientific support.

Effect of environmental factors on byssal thread formation

Abstract: The effects of various factors on byssal thread formation have been examined in the laboratory using Modiolus demissus and Mytilus edulis. With M. demissus thread formation (threads/mussel/h0 and proportion of mussels forming threads decreased with increasing size; prior exposure to air enhanced subsequent thread formation; mechanical agitation reduced thread formation. In addition, low salinity acclimated mussels adapted more rapidly to 32 ppt than high salinity acclimated mussels did to 16 ppt; threads were not formed in the absence of calcium and/or magnesium; and there was no reduction in thread formation at temperatures as high as 27° to 28°C. M. edulis died and thread formation approached zero at temperatures exceeding 26°C.

Assimilation of detritus and its associated bacteria by three species of estuarine animals

Abstract: The assimilation of detritus and its associated bacteria by three species of macrofauna which are abundant in eel grass beds during the summer was investigated in a laboratory study The amount of14CO2 respired per milligram of dry body weight by animals that fed on different types of labeled food was compared to determine the relative amount of assimilation of a particular food Animals were fed sterilized and unsterillized detritus labeled with14C to determine if they assimilated either the detritusper se or its associated bacteria as food

Integrated Fly Control Program for Caged-Poultry Houses

Abstract: In 1967 and 1968, populations of house flies, Musca Domestica L.; little house flies, Fannia canicularis (L.); black garbage flies, Ophyra leucostoma (Wiedemann), and predaceous manure-inhabiting mites (Parasitidae, Macrochelidae, and Uropodidae) at 3 poultry (caged laying hens) farms having a fly-control program were compared with 3 similar farms with no fly-control measures. Excellent fly control was demonstrated with a program based on early-season manure removal and adult fly control by insecticide-bait stations and 5 or 6 selective applications of insecticide to the inside upper parts of the poultry houses and the interior and exterior surfaces of the attached feed- and egg-storage buildings. Little house flies were controlled more easily than house flies. In the presence of a high population of black garbage flies at 1 farm in 1967, house flies and little house flies were rare. Populations of mites were variable, and no deterimental effects of the insecticide treatments were detected. The order of abundance was Urpodidae > Macrochelidae > Parasitidae. Parasitids appeared earliest in the season followed by macrochelids and uropodids, in that order. Toward the end of the fly season, parasitids disappeared first followed later by macrochelid and then uropodid population declines. A fly-activity index based on fecal spotting of white paper cards provided useful comparisons of farms, and development of that simple sampling tool is recommended.

Marking Host Eggs by Telenomus sphingis

Abstract: Most attacks on eggs of Manduca sexta (Johannson) (Lepidoptera: Sphingidae) by Telenomus sphingis (Ashmead) (Hymenoptera: Scelionidae) are followed by marking, a process lasting 1.5 minutes, during which time the female backs over the host and continuously rubs the tip of her moist ovipositor in a sinuous pattern over the egg surface. Seventy-seven percent of attacks were followed by marking, and oviposition occurred in 99% of marked eggs. Oviposition occurred in only 15% of unmarked attacked eggs. Females mostly refrained from ovipositing in marked hosts. Females having oviposited recently demonstrated greater discriminatory powers than those that had not laid eggs.

Pathogenicity of Salmonella gallinarum After Metabolic Injury by Freezing

Abstract: Freezing (-75 C) and storage (-20 C) of a cell suspension of Salmonella gallinarum resulted in a heterogeneous population of dead, metabolically injured, and unharmed cells. Injured cells constituted as much as 40% of those surviving freezing and storage for 1 day. Replica plating of frozen and thawed cells indicated metabolic injury was repairable and not a stable mutation. Penicillin was used to increase the ratio of injured to uninjured cells from a frozen and thawed cell suspension. Pathogenicity was evaluated by observing per cent mortality after injecting injured or uninjured cells into separate sets of chicks. Mortality differences between wholly uninjured and predominantly injured populations were small and consistent (5% level) with a hypothesis of no difference.

Nitrate reduction in the roots and shoots of wheat seedlings.

Abstract: Intact wheat seedlings cultured in high nitrate solutions (high-NO 3 - cultures) reduced NO 3 - when placed for 24 hr in dilute CaSO4 solutions although they leaked NO 3 - back to solution during this period. Most of the reduction seemed to occur in shoots since in parallel experiments detached shoots reduced nearly as much of the previously absorbed NO 3 - as intact cultures. Detached roots leaked greater quantities of NO 3 - back to solution than did intact cultures, and failed to reduce any of their previously absorbed NO 3 - during the experimental period. Seedlings of identical age cultured without a nitrogen source and rich in carbohydrate reserves (low-N cultures) rapidly absorbed NO 3 - from dilute Ca(NO3)2 solutions and reduced 80% of that absorbed. Detached low-N roots also absorbed NO 3 - and reduced 40% of that absorbed. Total NO 3 - reduction by intact low-N cultures over the 24-hr period was comparable to that of high-NO 3 - cultures in spite of the fact that in vitro nitrate reductase activity of the former did not reach the levels found initially or at the end of the period in the latter, and that the total NO 3 - absorbed by low-N cultures was less than that initially present in high-NO 3 - cultures.

The eta carbides in the Fe−W−C and Co−W−C systems

Abstract: The η carbides in Fe−W−C are Fe6W6C with an edge length of the cubic unit cella=10.956 to 10.958A and Fe3W3C witha=11.102 to 11.146A. In Co−W−C the η carbides solidity from the melt as Co6W6C and ∼Co2W4C. Co6W6C retains a narrow homogeneity range down to 1000°C with an observed range of lattice constants between 10.894 and 10.902A. The compositional range of Co2W4C spreads out between Co3W3C and Co2W4C at 1400°C and narrows back down to a small range around Co2W4C at 1000°C. Its lattice constants vary between 11.066 and 11.251A. In Fe-W-C a new hexagonal phase is found at FeW3C. It has the structure reported by Schonberg for Co3W9C4 and its lattice parameters area=c=7.806 to 7.810A.

A Note on Commuting Automorphisms of Rings

Abstract: (1970). A Note on Commuting Automorphisms of Rings. The American Mathematical Monthly: Vol. 77, No. 1, pp. 61-62.

Anomalous transport of hydrocarbons in polystyrene

Abstract: The transport kinetics and equilibrium concentrations of n-pentane at high penetrant activities in cast, annealed polystyrene were determined and compared with similar measurements in biaxially-oriented polystyrene. The rate of Case II (relaxation-controlled) sorption in biaxially-oriented polystyrene is three to four times faster than the sorption rate in cast, annealed polystyrene. The Case II sorption process in biaxially-oriented polystyrene is more highly temperature dependent than in cast, annealed film. The higher activation energies coupled with the larger relaxation-controlled sorption rates in biaxially-oriented polystyrene imply the involvement of larger polymer segments in the rate controlling polymer relaxations. The sorption in cast, annealed polystyrene was a position-dependent relaxation controlled transport process; in contrast the sorption in biaxially oriented polystyrene, albeit relaxation-controlled, was not position dependent. The position dependence of the Case II sorption appears to be a consequence of the presence of residual benzene in the film which accelerates the rate-determining relaxations. Desorption measurements at very low penetrant activities were quite similar for both biaxially oriented and cast, annealed polystyrene. The desorption kinetics were Fickian and were only a weak function of polymer orientation at these low activities.

Persistence of triazine herbicides in soils.

Abstract: Although phytotoxic residues of the triazine herbicides are objectionable when, in some soils and under some environmental conditions, sensitive plants are injured the season after application, residual activity is essential for weed control and soil sterilization. Without residual activity, frequent applications of less persistent herbicides would be necessary, and costs of weed control would, therefore, be high. A good example of the advantages of residual phytotoxicity was described by Horowitz (1964), who suggested that a single application of simazine or atrazine at the beginning of winter rains in Israel would control winter weeds and maintain sorghum planted the next spring free of weeds until harvest.

The American capital market, 1846-1914 : a study of the effects of public policy on economic development

Abstract: THE AMERICAN ECONOMY'S rapid industrialization during an extended period of falling prices in the late nineteenth century provides the backdrop for the problems explored in this study. Recent quantitative research has shown that a major feature of that historical experience was the economy's high and rising rate of capital formation. The period was also noted for great increases in the scale of operations of individual enterprises, often termed by later students the emergence of big business. The main questions about the period concern the role capital-market development played in these trends and whether that role was one of passive response to the requirements of, for example, more capital-intensive technologies, or whether exogenous, perhaps fortuitous, forces shaped the capital markets into active promoters of the trends. Analytically, the primary phenomena to be explained are the growing concentrations of funds in financial centers and the increased effectiveness with which these fund concentrations were allocated to industrial uses. The analysis undertaken leads to the conclusion that financial policies of the federal government played the chief role in fashioning the capital market into an engine of economic growth. The relevant policies, however, were formulated in response to exogenous factors-the financial requirements of the Civil War and the War's residue in the form of a greatly enlarged federal debt-rather than with a view toward promoting rapid economic growth. As is well-known amongst financial historians, a major reason for Congressional establishment of the National Banking System during the Civil War was the desire to provide a system of banks which would, by their very existence, provide a market for government bonds. The legislators also hoped that all commercial banks would join the new system, and with this in mind they enacted in 1866 a prohibitive tax on non-national-bank note issues. This retarded the growth of state-banking systems, but did not promote a unified banking development under federal law because high minimum-capital requirements and prohibition of real-estate loans served at the same time as long-term barriers to bank entry into the National System. The net result of these barriers to entry into both the non-national and national systems was to allow the development of monopolistic banking, especially in markets where the provisions of the federal banking laws were most restrictive of entry, namely, in small towns and the rural areas of the South and West. In city banking markets, where entry barriers were less operative, evidences of greater competition would be expected. Data on bank gross and net rates of return on assets, loan/asset ratios, and profit rates on equity were found to be consistent with the existence of differential degrees of monopoly. A variation of the theory of monopolistic price discrimination applies to banks in the late nineteenth century. Since banks paid interest on interbank deposits (bankers' balances), monopolistically-situated country banks always had the choice of placing funds in local loans or on deposit in the cities. The price-discrimination model explains why banks in the countryside, where interest rates were high, sent funds in