Life Sciences Commons^™

Cadmium And Zinc Levels In The Hair Of Smokers And Nonsmokers, Neal R. Simonsen

Dissertations and Theses

To determine the relationship of tobacco and marijuana smoking to levels of cadmium and zinc manifested in hair samples, a study was conducted at Portland State University using atomic absorption spectrophotometry. 97 adult student volunteers participated in the main study.

Characterization Of Gram-Positive Bacterial Isolates From Burn Victims, Trisha A. Hannan

Dissertations and Theses

Streptococcus and Staphylococcus were collected from patients hospitalized at the Oregon Burn Center, Emanuel Hospital, Portland, Oregon, between October 27, 1980 and January 1, 1981. Forty-five isolates of Staphylococcus and twenty-one isolates of Streptococcus, Lancefield Group D, were included in the investigation.

The objectives of the investigation were: (i) to identify to the species level all isolates, (ii) to determine their susceptibility to antimicrobial agents, (iii) to test the organisms. over time for increasing resistance to silver, (iv) to determine, if present, a bacterium harbored within the burn unit (nosocomial bacterium), and (v) to determine any recognizable pattern of successive …

A Geochemical Study Of The Rhododendron And Dalles Formations In The Area Of Mount Hood, Oregon, Marshall W. Gannett

Dissertations and Theses

The Miocene Rhododendron and Dalles Formations in the Mount Hood area are accumulations of chiefly pyroclastic andesitic material, largely confined to the Dalles-Mount Hood syncline. These very similar units are geographically separated by overlying andesites including the present Mount Hood cone, and past workers (Hodge 1938, Wise 1969) have suspected that they may share a common source. Prior to this study, few geochemical data were available for the Rhododendron and the Dalles Formations, compared to the well studied Columbia River basalts underlying them and the overlying Pliocene andesites. This geochemical study was designed to investigate certain aspects of the Rhododendron …

A Study Of Leslie Model Under Stochastic Environments, Kamran Shaukat

Dissertations and Theses

The prediction and analysis of changes in the numbers of biological populations rest on mathematical formulations of demographic events (births and deaths) classified by the age of individuals. The development of demographic theory when birth and death rates vary statistically over time is the central theme of this work. A study of the standard Leslie model for the demographic dynamics of populations in variable environments is made. At each time interval a Leslie matrix of survival rates and fertilities of a population is chosen according to a Markov process and the population numbers in different age classes are computed. Analytical …

Plasmid-Mediated Resistance To Arsenite And Arsenate In Escherichia Coli, Thomas Patrick Trezona

Dissertations and Theses

Bacterial strains resistant to arsenite, arsenate (or both) are readily isolated from nature. The resistance, in many cases, can be shown to be determined by conjugal plasmids. The mechanisms by which these plasmids confer resistance to arsenic compounds are entirely unknown. This study was undertaken to shed light on some of the physiological and genetic aspects of this resistance using plasmid-bearing strains of Escherichia coli which are highly resistant to both arsenite and arsenate. Most studies were carried out using E. coli J53 (R773) or the plasmid-free strain J53.

Variation In Branch Growth Characteristics Of Pinus Contorta Infected With Arceuthobium Americanum, Lynn Anne Larsen

Dissertations and Theses

Arceuthobium americanum is a flowering plant which parasitizes Pinus contorta (Lodgepole pine). This study examined branch performance of P. contorta infected to varying degrees with A. americanum.

A Genetic And Physiological Study Of An Arsenite Resistant, Uncoupled Mutant Of Escherichia Coli, Daniel Gordon Smiley

Dissertations and Theses

Chromosomally determined arsenate resistance in Escherichia coli is well characterized. Little, however, is known about chromosomally determined arsenite resistance in E. coli. Accordingly, spontaneous arsenite resistant mutants were selected in a plasmid free strain of E. coli. One mutant strain was analyzed in detail, genetically and physiologically. The mutation confering arsenite resistance was shown to be a single gene mutation. Genetic mapping studies using conjugation and transduction showed that the mutation was closely linked to the ilv region of the E. coli map.

The Metabolic Cost Of Behavioral Thermoregulation Of Body Temperature In The Northern Alligator Lizard Gerrhonotus Coeruleus, And How It Affects The Classical Concept Of Eurythermality, James Dudley Campbell

Dissertations and Theses

The effect of total metabolic cost expenditures on the precision of behavioral thermoregulation was investigated for the purportedly eurythermic Northern Alligator lizard (Gerrhonotus coeruleus). An operant apparatus was designed to test metabolic output at different heat reinforcement magnitudes. The mean T_B reflected in each trial was positively correlated to the length of reinforcement. The shuttle rate during each trial was inversely correlated to the length of reinforcement. The standard deviation and total metabolic costs did not vary significantly between trials undertaken at the same ambient temperature. Eurythermality in G. coeruleus is caused by fluctuations in preferred body temperature and …

Revetment Clearing, Its Influence On Riparian Mammal Communities, Robert E. Willis

Dissertations and Theses

Over 115 miles of rock revetment have been constructed in the Willamette Basin to protect river banks. This study examines the effect on riparian mammals of maintaining these revetments by vegetation and debris clearing. Differences between cleared and uncleared revetments were measured using a canopy coverage method of vegetation analysis; mammals were studied by trapping, by direct observation, and by noting such signs as scats, tracks, etc.