Thesis (M.S.)--University of Delaware, 2008. / Principal faculty advisor: Carlton R. Cooper, Dept. of Biological Sciences. Includes bibliographical references.

Thesis (M.Sc.)--University of Wollongong, 2004. / Typescript. Includes bibliographical references: leaf 90-98.

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Human food production activities can dominate natural systems, altering ecological and evolutionary aspects of the environment. Disease-mediated interactions are of particular concern. For example, parasites may "spill-over'' from farms to wildlife. Parasites isolated on farms can evolve resistance to treatment chemicals , but "spill-back'' from wildlife to farms may alter evolutionary dynamics. Here, we consider exchange of parasites (Lepeophtheirus salmonis) between wild (Oncorhynchus gorbuscha) and farmed salmon. We derive and analyze discrete-time models that implicitly include wild salmon migrations. First, we extend a standard fisheries model to show parasite exchange affects "line-dominance'' in the population ecology of salmon. Second, we extend a classic population genetics model to show that wild salmon can theoretically provide an "ecosystem service'' by delaying the onset of chemical resistance in parasites on farms. This service, however is affected by a nonlinear feedback if farm parasites spill-back to affect wild salmon. / Applied Mathematics

Thesis (M.S.)--University of Delaware, 2009. / Principal faculty advisors: Thomas M. Church and Thomas E. Hanson, College of Earth, Ocean & Environment. Includes bibliographical references.

The FDOT has been using supplementary cementitious materials while constructing steel reinforced concrete marine bridge structures for over 3 decades. Previous findings indicated that such additions in concrete mix makes the concrete more durable. To better understand corrosion propagation of rebar in high performance concrete: mature concrete samples that were made (2008/2009) with Portland cement, a binary mix, a ternary mix and recently prepared (April 2016 with 50% OPC + 50% slag and 80% OPC + 20% Fly ash) concrete samples were considered. None of these concretes had any admixed chloride to start with. An accelerated chloride transport process was used to drive chloride ions into the concrete so that chlorides reach and exceed thechloride threshold at the rebar surface and initiate corrosion. Electrochemical measurements were taken at regular intervals (during and after the electro-migration process) to observe the corrosion propagation in each sample. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection

Two duplex stainless steels rebars: UNS32304SS and UNS32101SS, were selected to investigate the corrosion initiation and propagation in reinforced concrete specimens. The investigation is divided in two phases with two different methods to accelerate the transport of chlorides through the concrete and initiate corrosion in a short period of time. After corrosion had initiated and propagated for some time; selected specimens were terminated for visual examination. On specimens selected for autopsy, the rebars in the top row showed corrosion to various degrees. Corrosion had propagated to such extent on the terminated specimens that the specimen showed cracks. Stray current might have caused accelerated corrosion on rebars where corrosion had initiated. Based on chloride concentrations measured at the rebar trace, corrosion initiated: on S32101 rebars on average at 7.9 kg/m3, and S32101 rebars on average at 6.0 kg/m3. The findings suggest that S32304 rebars corroded at a slower than S32101. / by Francisco Gutierrez Tellez. / Thesis (M.S.C.S.)--Florida Atlantic University, 2013. / Includes bibliography. / Mode of access: World Wide Web. / System requirements: Adobe Reader.

With the need to improve corrosion resistance in columns and piles, the innovative idea of Centrally Prestressed Fiber Reinforced Concrete (CPFRC) columns is a promising solution. The first step is to compare if the compressive strength of any mix is affected by the size, geometry, or even the inclusion of polyolefin fibers in a specimen. The results showed that the cylinder size of 4 in. x 8 in., which is the most common size used by the testing labs, has the highest compressive strength. There was no sign on compressive strength improvement with the use of polyolefin fibers, except for reduction in cracking size and concrete spalling. The second step compared the ultimate strength, ductility characteristics and failure mode of CPFRC columns to conventional columns. CPFRC showed adequate axial and flexural resistance, in addition to ductile behavior similar to regular reinforced concrete columns. / by Daniel A. Grijalba. / Thesis (M.S.C.S.)--Florida Atlantic University, 2011. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2011. Mode of access: World Wide Web.

Chloride ions present in the marine atmosphere contained in marine aerosols is investigated for a relationship with chloride that accumulated into concrete. Chloride profiles are conducted on several concrete mixes containing fly ash, silica fume, and slag, with water to cementitious ratios of 0.35, 0.41, and 0.47. The chloride accumulation in concrete samples exposed to the environment is investigated with relation to the chloride deposition from the marine atmosphere measured via the wet candle test. Results indicate a possible relationship for the total accumulated chloride in the concrete with the accumulated chloride deposition (wet candle). Over the exposure periods, concrete specimens with 50% slag addition and 0.47 w/cm had the lowest average rates of chloride accumulation for deposition under 100 g/m2day. Chloride accumulation was lower in concrete containing 20% fly ash and 8% silica fume with 0.35 w/cm for chloride deposition rates over 200 g/m2day. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection

The corrosion propagation stage of D-CRP (types F and C) was tested under immersion in water, high humidity, and covered with wet sand. The half-cell potential, linear polarization test, and electrochemical impedance spectroscopy measurements were performed. Selected specimens were terminated after 300 days of exposure and visually inspected. Based on corrosion potential measurements obtained during the corrosion propagation observation, and calculated corrosion rate based on LPR measurements: all specimens were actively corroding. Additionally, EIS-Rc values were calculated for FS, CS and CH specimens. The Rc_EIS were generally greater than Rc_LPR values. EIS spectra for CI and FI specimens usually included mass transport limitations, as these specimens were immersed. Both type of specimens immersed in water (FI and CI), appeared to have higher corrosion rate based on LPR-Rc. However, upon autopsy it was revealed that a more modest amount of corrosion occurred on the reinforcing steel of FI and CI terminated specimens. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection