Digital Commons Network^™

Measurement Of Deforestation In The Brazilian Amazon Using Satellite Remote Sensing, David Lewis Skole

Doctoral Dissertations

A clear understanding of the role of the biota in the global carbon cycle is limited by an absence of accurate measurements of deforestation rates in the tropics. This study measures the rate and extent of deforestation in the Brazilian Amazon, a tropical forest biome approximately 5 $\times$ 10$\sp6$ km$\sp2$ in size and the largest extant tropical forest biome in the world. The study focuses on remote sensing measurements of deforestation rates and the area of secondary vegetation, but also utilizes tabular data to document deforestation when satellite data are not available. The analysis concludes: (1) Regression analysis of SPOT, …

Discards Of Commercial Fish Species In The Gulf Of Maine Groundfish And Shrimp Fisheries, Richard Langan

Doctoral Dissertations

A three part analysis of discarding of commercial fish species in the Gulf of Maine trawl fisheries was conducted from 1983 through 1992. Abstracts for each part of the dissertation are:

Part 1. The objectives of the research were to quantify commercial trawler discards of American plaice, witch flounder, yellowtail flounder, and winter flounder, and to examine variables that potentially influence discard rates. Data were obtained from 135 tows in 6 areas of the Gulf of Maine. Four different types of trawls were used. Mean discard percentages per tow, on a weight basis, were 25, 18, 13, and 5% for …

Horizontal Distribution, Feeding Rates And Prey Selectivity Of The Littoral Predator, Polyphemus Pediculus, Anne Turner Packard

Doctoral Dissertations

Littoral planktonic communities have rarely been included in food web dynamics and predator/prey behavior studies of planktonic communities of fresh water ecosystems. Polyphemus pediculus, a typically littoral predaceous cladoceran, is common in lakes and ponds throughout the northern temperate zone.

The patchy distribution of Polyphemus in littoral surface waters necessitates the use of a stratified random sampling regime to estimate and monitor Polyphemus populations. The population in Mirror Lake, NH, increased exponentially after the first appearance of parthenogenetic juveniles in late April. An abrupt decline in the population coincided with the movement of small Micropterus dolomieui fry into littoral areas …

Intraspecific Variability And Phylogeny Of Sibling Species Of Simulium Venustum And S Verecundum Complexes (Diptera: Simuliidae) Revealed By The Sequence Of The Mitochondrial Large (16s) Ribosomal Rna Gene, Bai Xiong

Doctoral Dissertations

This study demonstrates that material preserved in Carnoy's solution (1:3 = glacial acetic acid:alcohol) can be amplified by the polymerase chain reaction for determination of DNA sequence. Because only a single salivary gland from the black fly larva is necessary for DNA extraction, both DNA sequence and chromosome banding data can be obtained from the same individual. This technique reduces potential contamination of the sample by foreign DNA in the gut and/or on the cuticle of the larva and eliminates the possibility of misidentified larvae in the sample. Surveys using the mitochondrial large rRNA gene revealed extensive intraspecific variation in …

The Role Of Lipoteichoic Acid And The Leukocyte Integrins In The Binding Of Group B Streptococci To Murine Peritoneal Macrophages, Anne Ragonese Sloan

Doctoral Dissertations

The macrophage has been shown to bind potentially pathogenic bacteria in the absence of serum components, but the mechanism is not well understood. The macrophage is a key component of our non-inducible defenses and this form of innate immunity is of particular importance for individuals in which the immune system may be sub-optimally functional, e.g., neonatal and geriatric individuals, and for sites in the body in which serum enhancement through opsonins is thought to be insufficient, e.g., lungs. To understand the mechanism by which mammalian innate host defenses respond to potential microbial aggression by opportunistic microorganisms, I developed two assays …

Techniques For Enumerating Protozoa In Saturated Subsurface Sediments, Amoret L. Bunn

Doctoral Dissertations

Three techniques were investigated for the enumeration of small (2-5 $\mu$m in diameter) flagellates and amoebae in sediments collected within and outside of a wastewater contaminated ground water plume at the U.S. Geological Survey Toxic Substances Hydrology Research site, located on Cape Cod, MA. An epifluorescent direct count technique was developed to enumerate DAPI stained protozoa on polycarbonate membrane filters. These estimates were compared to the those from the Darbyshire liquid media MPN and Singh solid media MPN techniques. In Fall 1991, sediment samples were collected to investigated the variability of the hold time of cores, total and encysted protozoan …

Gene-Encoded Surface Antigens Of Legionella Pneumophila And Their Role In Pathogenicity, Andrea S. High

Doctoral Dissertations

The pneumonial agent, Legionella pneumophila, is the predominant bacterium responsible for Legionnaires' disease. Experimentally, these organisms have demonstrated the ability to adhere to host cells without the presence of a mucopolysaccharide layer.

A recombinant plasmid, pLP 116, resulting from the ligation of a Hae III digest from the L. pneumophila, Nottingham N$\sb7$ genome and Sma I-digested pUC 19 vector was shown to encode for a 25 kilodalton (kDa) major outer membrane protein (MOMP) of L. pneumophila by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS). This protein was detected on the surface of an E. coli clone (LP 116) by immunoassays. …

Predator-Prey Interactions Between Fish And Insects In Streams, Graham Edward Forrester

Doctoral Dissertations

Some benthic insects in streams disperse by drifting short distances downstream in the water column. While drifting they are at risk from predators, such as trout, that feed in the water column. I examined prey selection by brook trout (Salvelinus fontinalis L.) in Stoney Brook, New Hampshire, U.S.A., and effects of trout on drift dispersal and benthic density of five prey taxa (mayflies: Ephemeroptera).

Effects of trout on mayflies were tested by field manipulation of trout density in replicate 35 m long sections of stream. Trout consumed all five mayflies in roughly similar numbers. Feeding rates of trout (by weight) …

Genetic And Morphological Variation And Differentiation Of South Korean Natural Populations Of Wild Soybean, Glycine Soja Sieb And Zucc, Hongrun Yu

Doctoral Dissertations

Genetic variation is the basis of crop improvement. As genetic background narrows in the cultivated germplasm, genes need to be introduced from new sources. Glycine soja is a wild relative of the cultivated soybean, glycine max (L.) Merr. It can be used in soybean breeding. Evaluation of wild soybean populations is not only necessary for use in cultivar improvement, will also provide information about origin, migration, evolution and natural selection of this species. Seeds were collected from six natural populations in South Korea to study the genetic variation and differentiation of wild soybean.

The study was divided into two parts: …