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The arrival order of species, also known as priority effects, can have big impacts on the future plant community assembly and diversity. Knowledge about priority effects can be of importance in grassland restoration and to counteract invasive species invasion. The aim of this study was to evaluate if and how much plant traits change with arrival order. Here, 15 grassland species, divided into functional groups (forbs, grasses, and legumes) were sown in a greenhouse. The plants were subject to one of three treatments: ‘Control Alone’ (CA), where each plant was grown alone, ‘Control Together’ (CT), where two plants arrived at the same time and ‘Priority effect’ where the first plant (PE.1) arrived three weeks before the second plant (PE.2). For plants grown alone, there was significant differences between the functional groups for the traits mass relative growth rate, height relative growth rate, plant height, plant width and width of stolons. Forbs had significantly largest relative growth rate (RGR), smallest height after three and six weeks of growth as well as largest stolons at both times. Grasses showed significant largest width at three weeks of growth and legumes reached about the same width as grasses after six weeks of growth. The plants that arrived second showed significantly less growth compared to the other treatments which imply that priority effects occurred. The growth strategy for forbs was fast RGR and production of stolons, for grasses it was primarily an increased width and for legumes it was a combination of reaching large height and width.

Floodplain is an important location for the economic and social development of society throughout history, although it afflicted by different disasters like floods and bank erosion from time to time. Population dynamics and distribution trends have important effects on the landscape and society. Population dynamics in floodplains influenced mostly by the flood events and related human activities to protect themselves and the properties. Thus, floodplain population dynamics is vital to understand human-nature relationships, disaster risk assessment, flood forecasting and flood damage costs in the floodplains. Economic losses and fatalities due to flood events increase with increased flood frequency and flood magnitude. Extreme hydrological changes are responsible for such changes in the flood events. Population growth, urbanization and developmental activities worsened the situation further in the floodplain areas. Learning effect, i.e. flood memory is noticeable after the flood which diminishes with time, however, levee, which is a popular flood protection measure, causes further reduction of learning effect. Researchers suggest that levees create a false sense of safety and can influence the mobilization of floodplain population. Several pieces of research indicate that along with flood events and intervention measures, inundation depth, durations, flood type (coastal/ riverine), economic, technological and political characteristics of the societies influence flood memory, hence, influence floodplain population dynamics. However, long term floodplain population dynamics and how it is related to different flood-related, i.e. hydrological and sociological variables are yet to be confirmed. Flood is one of the major natural disasters in the United States. About 10% of the population lives in the 100-year and 500-year floodplain of the United States. This study carried out to investigate the long-term trend of floodplain population dynamics in the USA and how the dynamics changes from country to state to county level considering Arkansas State and Sebastian County to observe the difference. Also, the relationships of floodplain population dynamics with hydrological and sociological variables such as flood events, damage, intervention measures and poverty assessed in the national, state and county level. Then the dynamics of the national level, the state (Arkansas) level and the county (Sebastian) level were compared to identify changes in dynamics from macro to micro-scale. Floodplain population dynamics evaluated in terms of population growth rate and the ratio of floodplain population to the total population from 1790 – 2010. The median centroids of the population growth rate from 1790 – 2010 were estimated to observe the changes in the central tendency of the population growth rate in the total area and in the floodplain overtime to locate the typical place of floodplain population growth. High-resolution raster image (1 km x 1 km) of historical population data and a high-resolution raster image (250 m x 250 m) of floodplain data were analysed using ArcGIS to evaluate floodplain population dynamics. Historical data regarding flood events, damage, structural and non- structural flood intervention measures and poverty from available databases were extracted, processed and analysed to establish the relationship among population dynamics, hydrological and social variables. Finally, the population dynamics of the three levels were compared statistically and discussed for changes. It is found that the central tendency of the total population growth rate and floodplain population growth rate of the USA shifts from east to west direction. The central tendency of the overall population growth rate located near the lower Mississippi river basin in the 1800s. It is consistent near the geographical centroid of the USA in Kansas since 1900. For the floodplain population, the central tendency of the growth rate stayed consistent in Arkansas from 1910 – 2010, i.e. in the lower Mississippi river basin. This location indicates the floodplains in Arkansas was preferable for floodplain population settlement for many decades. Change in floodplain population proportion of the whole country USA from 1790 – 2010 shows that the proportion of floodplain population is more than 80% during the initial years of settlement. Then it reduced to less than 40% over time. At the state level – Arkansas, the proportion of floodplain population is also more than 80% during initial settlement and reduced to less than 60% over time for counties with high percentage floodplain area. Flood events, structural and non-structural protection measures influenced floodplain population dynamics over time and learning effect, i.e. social memory of flood found was seven years. At the county level- Sebastian county, Arkansas, the proportion of floodplain population varies significantly with a variance of 0.04 and a standard deviation of 0.19. The ratio of floodplain population in Sebastian was 29% in 1820, which increased and decreased over the years and about 70% in 2010. In addition to flood events, different intervention measures, the floodplain population dynamics in the Sebastian county are influenced by the social, economic and political phenomenon, examining which is out of the scope of this study. The learning effect of flood seems to be eight years in the case of Sebastian county. The population dynamics influenced by a different social, geographical, economic, political and hydrological phenomenon which makes it a complicated system to comprehend within the present scope of the study. The result shows that the floodplain population dynamics can vary for different geographical scale. Therefore, the geographic extent should also need to consider while using population dynamics in flood disaster management and mitigation strategy development, policy formulation and implementation. / Flodslätter är viktiga platser för samhällets ekonomiska samt sociala utveckling och har varit det sedan är lång tid tillbaka, även om de från och till har drabbats av olika katastrofer såsom översvämning och erosion. Översvämning är en av de största naturliga katastrofer som sker i USA. Ungefär 10 % av befolkningen bor i 100- och 500-års flodslätter som emellertid förändras på grund av olika anledningar, inklusive översvämningar. I denna studie undersöks den tillfälliga relationen mellan översvämning, relaterad skada, olika ingripande åtgärder och fattigdomsnivå med en befolkningsdynamik i flodslättsområden. Vidare sker denna undersökning i tre olika nivåer – nationellt: USA som ett helt land, stats-nivå: Arkansas och län: Sebastian County, Arkansas där de olika dynamikerna i de tre nivåerna jämförs. På den nationella nivån utvärderades befolkningsdynamiken med avseende på flodslätten till den totala populationen och befolkningstillväxt. Resultatet visar att befolkningsdynamiken förändras beroende på om den betraktas ur ett nationellt, statligt eller läns perspektiv. Ur ett nationellt perspektiv flyttar flodslättsbefolkningar till olika områden med tiden. Ur ett statligt perspektiv är flodslättsbefolkningar känsliga mot översvämningar, skada och olika ingripande åtgärder. På länsnivå, utöver översvämningsrelaterade variabler, är flodslättsbefolkningar känsliga mot andra socio-ekonomiska faktorer som inte behöver vara relaterade till översvämningar. Resultatet indikerar således att översvämningar inte alltid behöver vara den faktorn som styr befolkningsdynamiken i flodslättsområden på den lokala nivån samt beslutet att flytta till en flodslätt påverkas av olika socio- ekonomiska faktorer, inklusive översvämning. På den nationella nivån kan däremot både påverkan av översvämningar och relaterade variabler på befolkningsdynamiken i flodslättsområden observeras.

A number of innovative nitrogen removal technologies have been developed to address the treatment challenges caused by stringent regulations and increasing chemical and energy cost. A major contributing factor to these challenges is the liquid stream originating from the process of dewatering anaerobically digested solids. This liquid, also knows as centrate, reject water or sludge liquor, can cause an increase of up to 25% in ammonia loading. The recently discovered anaerobic ammonia oxidation (anammox) process is a major breakthrough for treatment of these streams as it has the potential to remove up to 85% of nitrogen load without external carbon source addition. The anammox process is combined with another process that oxidizes half of the ammonia to nitrite (nitritation) in a separate reactor such as in the SHARON process, or in the same reactor such as in the DEaMmONification (DEMON) process. Despite intensive laboratory research for the last 10 years to fully understand these processes, there is still a high level of skepticism surrounding the implementation of full-scale systems. The reason for this skepticism could be due to frequent failures observed in the lab scale systems as well as reported slow bacterial growth. We think that this technology might be used more effectively in the future if process kinetics, inhibition and toxicity can be better understood. This work focused on the DEMON process with a goal to understand the kinetics and inhibition of the system as a whole and the anammox process in particular. A DEMON pilot study was undertaken at the Alexandria Sanitation Authority (ASA) and had several study participants, including ASA, the District of Columbia Water and Sewer Authority (DCWASA), CH2M Hill Inc., Envirosim Ltd, the University of Innsbruck and Virginia Tech. We investigated the growth rate of anammox bacteria within a quasi-optimal environment. Laboratory-scale experiments were conducted to assess anaerobic ammonia oxidation inhibition by nitrite as well as aerobic ammonia oxidation inhibition by compounds present in the DEMON reactor feed, such as a defoaming agent, a sludge conditioning polymer, and residual iron from phosphorus removal practices. The study revealed that the DEMON process can be efficiently controlled to limit nitrite accumulation capable of causing process inhibition. The target ammonium loading rate of 0.5 kg/m3/d was reached, and no upset was noticed for a loading up to 0.80 kg/m3/d with an HRT of 1.7 days. The ammonia removal efficiency reached an average of 76% while total nitrogen removal efficiency had an average of 52%. Most of the process upsets were caused by aerobic ammonia oxidation failure rather than anammox inhibition. Failure in ammonia oxidation affected pH control, a variable which is at the center of the DEMON process control logic. The pilot study is summarized in Chapter 3 of this Dissertation. The low anammox maximum specific growth rate (µmax,An) as well as nitrite inhibition are historically reported to be the major process challenges according to the literature, but the degree to which each contributes to process problems differs widely in the literature. In this study, we estimated µmax,An by using the high F:M protocol commonly used for nitrifying populations. We also studied the effect of both short term and sustained nitrite exposure on anammox activity. In this study, µmax,An was estimated to be 0.017 h-1. The study results also suggest that anammox bacteria can tolerate a spike of nitrite-N at concentrations as high as 400 mg/L as long as this concentration is not sustained. Sustained concentrations above 50 mg/L caused a gradual loss of activity over the long term. Finally, the inhibition of aerobic ammonia oxidizing bacteria (AerAOB) observed in the DEMON reactor was investigated using laboratory experiments and is reported in Chapter 6. AerAOB inhibition was, in most cases, the main reason for process upset. Compounds that were suspected to be the cause of the inhibition were tested. The study noticed that a defoaming agent, polymer and ferrous iron had some inhibiting properties at the concentrations tested. / Ph. D.

The effect of maternal dietary fats on growth rate and bone development of commercial broilers was examined. Addition of fats [soybean oil (SBO), menhaden oil (MO) and chicken fat (CF)] to the maternal diet altered the tissue and yolk composition of the hens to reflect the dietary fat source. Day-old chick tissues from hens fed MO diet exhibited greater (P ≤0.01) amounts of EPA (20:5n3), DPA (22:5n3), DHA (22:6n3) and total ω-3 fatty acids, and significantly (P ≤0.01) less 20:4n6 than those from hens fed SBO and CF diets. Tissues of day-old chicks from SBO fed hens had larger amounts of 18:2n6, 18:3n3 and total w-6 fatty acids compared to those from CF and MO maternal diets (P ≤ 0.01). These differences disappeared at 4 (WOA) weeks of age. Male and female chicks from the MO maternal diet were lighter (P ≤0.01) during the grow out period than those from CF and SBO diets. Chick tibiae width and diameter from the SBO maternal diet tended to be larger than the MO maternal diet, with significance being noted at d 14 (P ≤ 0.01) and 28 (P ≤ 0.01). Increases (P ≤ 0.01) were observed in shear force and stress required to break chick tibiae from the SBO maternal diet compared to those from the CF and MO maternal diets. The SBO maternal diet stimulates growth rate and bone development and strength of the progeny. / Master of Science

The phenotypes of hatchling reptiles are influenced by the environmental conditions that embryos experience during incubation, by yolk invested into the egg, and by the genetic contributions of the parents. Phenotypic traits are influenced by these factors in ways that potentially affect the fitness of hatchlings. The physical conditions that embryos experience within the nest affects development, hatching success, and hatchling phenotypes. Thus, the nest site that a female selects can influence the survival of her offspring as well as her overall fitness. In Chapter 1, I addressed this issue through a nest site selection experiment designed to determine the substrate temperature and moisture conditions that female eastern fence lizards (Sceloporus undulatus) select when provided a range of conditions from which to choose. In general, I found that females selected nest sites with conditions that yield high hatching success. In Chapter two, I investigated the relative contributions of incubation moisture conditions, maternal yolk investment, and clutch (genotype) to variation in hatchling phenotypes and survival under field conditions. Eggs from 28 clutches were distributed among two moisture treatments; wet (-150 kPa) and dry (-530 kPa). In another treatment, yolk was removed from eggs to determine the affect of yolk quantity on hatchling phenotypes. After hatching, several phenotypic traits (mass, snout-vent length, tail length, body shape, thermal preference, running speed, desiccation rate, and growth rate) were measured. Hatchlings were subsequently marked and released at a field site in southwest Virginia. Hatchlings were recaptured twice weekly prior to winter and the following spring to monitor growth and survival. I found that incubation moisture and yolk removal affected only hatchling body size; individuals from the dry and yolk removed treatments were smaller in body size than those from the wet treatment. However, clutch was the most important source of phenotypic variation; all phenotypes were affected by clutch. Significant clutch effects suggested the possibility that phenotypic variation had at least some genetic basis. In the field, survival was not affected by incubation moisture and yolk removal, and overall survival was not associated with hatchling body size. Survivors and nonsurvivors differed only in growth rate in the field and running speed measured in the laboratory. Survivors ran faster and grew more slowly than nonsurvivors. To examine the association of clutch with survival, I used clutch mean values to look at the relationship between phenotype and survival. Clutches that produced relatively slow growing individuals and fast runners had higher survival rates than clutches that produced relatively rapid growing individuals and slow runners. In order to grow rapidly, an individual must eat more than slowly growing individuals. Thus, rapid growth rate may increase risk of predation through its association with foraging activity. Individuals that run fast should be capable of capturing prey and evading predators more effectively than individuals that run slowly. Overall, these results emphasize the importance of clutch to variation in phenotypes and survival in hatchling Sceloporus undulatus. / Master of Science

Thesis (MBA (Business Management))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: Despite growth being the target of all business operations, there is a concrete limit to growth. The concept of a sustainable cash flow growth rate is an important consideration, since it alerts management to cash flow shortfalls caused by a too-high growth rate. The company Homechoice Holdings Limited was chosen as the subject of this research report as it exhibited unusually high revenue growth, linked to a high share price and a subsequent cash shortfall. The tool of a sustainable growth rate model was employed to investigate whether the shortfall in cash could have been averted if the cash flow sustainable growth rate (CFSGR) had been adhered to. A selection of existing sustainable growth rate models is presented and their different emphases are discussed. This is followed by the development of a sustainable growth rate formula, which is applied to five general cases. In case 1, there is a dividend, depreciation, fixed expenses as well as a change in the working capital cycle (WCC). In case 2, depreciation, fixed expenses and a change in WCC are evident, but the dividend is zero. In case 3, depreciation and a change in WCC are evident, but dividend and fixed expenses are zero. In case 4, all items are zero excepting a change in WCC. In the final case, 5, all items are zero. The published financials of the years 1996-2000 are analysed in detail and the market reaction (share price and press reaction) is portrayed. Lastly the actual developments of the profits and the share price are compared with a hypothetical case in which the previously defined CFSGR would have been used. In conclusion the issue of the CFSGR is contextualised with other information which contributed to the decline of this company. / AFRIKAANSE OPSOMMING: Hoewel groei die teiken van alle sakebedrywighede is, het groei ’n konkrete limiet. Die konsep van ’n volhoubare kontantvloei-groeikoers is ’n belangrike oorweging omdat dit bestuur waarsku wanneer daar kontantvloeitekorte is wat veroorsaak word deur ’n groeikoers wat te hoog is. Die maatskappy Homechoice Holdings Beperk is as onderwerp van hierdie navorsingsverslag gekies as gevolg van sy buitengewoon hoë inkomstegroei wat aan ’n hoë aandeelprys en ’n gevolglike kontanttekort gekoppel is. ’n Volhoubare groeikoersmodel word as hulpmiddel gebruik om ondersoek in te stel of die kontanttekort verhoed kon word indien die maatskappy die kontantvloei volhoubare groeikoers (CFSGR) gebruik het. ’n Seleksie van bestaande volhoubare groeikoersmodelle word aangebied en die verskillende elemente wat hulle beklemtoon word bespreek. Dit word gevolg deur die ontwikkeling van ’n volhoubare groeikoersformule wat op vyf algemene gevalle toegepas word. In geval 1 is daar ’n dividend, depresiasie, vaste koste sowel as ’n verandering in die bedryfskapitaalsiklus. In geval 2 is depresiasie, vaste koste en ’n verandering in die bedryfskapitaalsiklus voor die hand liggend, maar die dividend is nul. In geval 3 is depresiasie en ’n verandering in die bedryfskapitaalsiklus voor die hand liggend, maar dividende en vaste koste is nul. In geval 4 is alle items nul buiten ’n verandering in die bedryfskapitaalsiklus. Laastens, in geval 5, is alle items nul. Die gepubliseerde finansiële jaarstate van 1996 tot 2000 word breedvoerig ontleed en die markreaksie (aandeleprys en mediareaksie) word aangetoon. Laastens word die werklike ontwikkeling van die winste en die aandeleprys met ’n hipotetiese geval vergelyk waarin die CFSGR, wat vroeër gedefinieer is, gebruik is. Die kwessie van die CFSGR word ook in ’n konteks geplaas saam met ander inligting wat tot die agteruitgang van hierdie maatskappy bygedra het.

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