Fish movement, habitat selection, and stream habitat complexity in small urban streams

Urbanization impacts have become more evident in the last 30-50 years, due to human population increase and subsequent land use change. Many aspects of stream ecosystems are influenced including hydrology, geomorphology, water quality, ecosystem function, riparian vegetation, and stream biota. Effects of urbanization on ecosystem structure and function are discussed, and the urban stream syndrome is introduced in Chapter 1. Chapter 2 reports differences in stream fish assemblages in the eastern Piedmont and Coastal Plain of Maryland, USA due to urbanization, and establishes a foundation for hypotheses presented in subsequent chapters. Chapter 3 describes a physical habitat survey that attempts to understand what instream and channel habitat attributes change across the urban-rural gradient (0-81% urban land use; ULU). While changes in stream habitat appear at 30% ULU, significant impacts occurred once a watershed has >45% ULU, at which point stream channels can not accommodate the power and intensity of impervious surface runoff. Fish habitat patch selection is examined in Chapter 4, which involved instream habitat manipulation experiments. I tested fish selection response of instream habitat using three treatments (woody debris, shade, and both) in first order urban (>60% ULU), suburban (27-46% ULU), and rural (<15% ULU) eastern Piedmont streams in Maryland. Blacknose dace (BND) Rhinichthys atratulus and creek chub (CKB) Semotilus atromaculatus selected shade and woody debris combined significantly more than other treatments in rural and suburban streams. Urban fish selected the shade treatment the most of all enhancements. CKB who selected the enhancement were significantly larger than those found in the control. Urban fish prefer shaded habitat providing overhead protection due to the general lack of habitat complexity in urban channels. CKB behavior may indicate intraspecific competition, particularly between juvenile and adult individuals for prime habitat positions. Chapter 5 presents a fish movement study, comparing rural and urban fish population behaviors. Urban BND and CKB displayed significantly larger home ranges than rural fish. The rural fish movement distribution was more leptokurtic. Competitive interactions are suggested as the reason for greater movement in urban stream populations. Finally, conclusions are submitted with significant findings in Chapter 6

Pathways of Resistance to Thymineless Death in Escherichia coli and the Function of UvrD

Thymineless death (TLD) is the rapid loss of viability in bacterial, yeast, and human cells starved of thymine. TLD is the mode of action of common anticancer drugs and some antibiotics. TLD in Escherichia coli is accompanied by blocked replication and chromosomal DNA loss and recent work identified activities of recombination protein RecA and the SOS DNA-damage response as causes of TLD. Here, we examine the basis of hypersensitivity to thymine deprivation (hyper-TLD) in mutants that lack the UvrD helicase, which opposes RecA action and participates in some DNA repair mechanisms, RecBCD exonuclease, which degrades double-stranded linear DNA and works with RecA in double-strand-break repair and SOS induction, and RuvABC Holliday-junction resolvase. We report that hyper-TLD in ∆uvrD cells is partly RecA dependent and cannot be attributed to accumulation of intermediates in mismatch repair or nucleotide-excision repair. These data imply that both its known role in opposing RecA and an additional as-yet-unknown function of UvrD promote TLD resistance. The hyper-TLD of ∆ruvABC cells requires RecA but not RecQ or RecJ. The hyper-TLD of recB cells requires neither RecA nor RecQ, implying that neither recombination nor SOS induction causes hyper-TLD in recB cells, and RecQ is not the sole source of double-strand ends (DSEs) during TLD, as previously proposed; models are suggested. These results define pathways by which cells resist TLD and suggest strategies for combating TLD resistance during chemotherapies

Lung Cancer and Cardiovascular Disease Mortality Associated with Ambient Air Pollution and Cigarette Smoke: Shape of the Exposure–Response Relationships

Background: Lung cancer and cardiovascular disease (CVD) mortality risks increase with smoking, secondhand smoke (SHS), and exposure to fine particulate matter < 2.5 μm in diameter (PM2.5) from ambient air pollution. Recent research indicates that the exposure–response relationship for CVD is nonlinear, with a steep increase in risk at low exposures and flattening out at higher exposures. Comparable estimates of the exposure–response relationship for lung cancer are required for disease burden estimates and related public health policy assessments

n Eksemplariese studie van die eietydse andragogiese nood

Proefskrif (M. Ed.) -- Universiteit van Stellenbosch, 1995.Full text to be digitised and attached to bibliographic record

The Effect of Trichoderma harzianum on Honey Bee Survival

NYS IPM Type: Project ReportBotrytis cinerea is a fungal pest of berry fruit that causes gray mold or fruit rot. Infection usually occurs in the flower, remains quiescent until the fruit matures, and then develops abundantly, causing fruit decay. One biological control agent of B. cinerea that is commercially available is the fungal antagonist, Trichoderma harzianum

Developing a local framework for quality in an online learning environment : a case study

This paper describes a quality framework for the development of a set of online learning resources, namely worked examples with audio enhancement and simulations, used to improve the offering of a level one business mathematics course at Central Queensland University. The framework centres around five criteria that emerged as the resources were developed. They were a primary reference determining the quality of the learning environment created

Adopting a learner-centred focus with online delivery of service mathematics

With the advantage of hindsight, the comparison drawn by James Kaput in 1992, likening the task of describing the role of technology in mathematics education to that of attempting to describe a newly active volcano, appears an astute observation. His statement acknowledges the pressure that advances in technology exert as they move to drive education and the discipline of mathematics from outside and simultaneously act to support learning from within. This paper discusses a role for technology in mathematics education that few vlIiters foresaw at the end of last centtuy; that is, through the World Wide Web to offer online delivery of mathematics in environments that centre on the individual learner and their needs. The case for online delivery as a medium that adopts a leamer-centred focus is put forward. This paper discusses an initiative to develop a leamer-centred environment for a level-one business mathematics course at Central Queensland University. It win be maintained that the creation of such a learning environment offers individual mathematics-learners opportunities for understanding above and beyond those offered through traditional media

Adopting a learner-centred focus with online delivery of service mathematics

With the advantage of hindsight, the comparison drawn by James Kaput in 1992, likening the task of describing the role of technology in mathematics education to that of attempting to describe a newly active volcano, appears an astute observation. His statement acknowledges the pressure that advances in technology exert as they move to drive education and the discipline of mathematics from outside and simultaneously act to support learning from within. This paper discusses a role for technology in mathematics education that few vlIiters foresaw at the end of last centtuy; that is, through the World Wide Web to offer online delivery of mathematics in environments that centre on the individual learner and their needs. The case for online delivery as a medium that adopts a leamer-centred focus is put forward. This paper discusses an initiative to develop a leamer-centred environment for a level-one business mathematics course at Central Queensland University. It win be maintained that the creation of such a learning environment offers individual mathematics-learners opportunities for understanding above and beyond those offered through traditional media