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Meachen-Samuels, Julie Anna. "Morphological indicators of prey-size preference in the Felidae." Diss., Restricted to subscribing institutions, 2008. http://proquest.umi.com/pqdweb?did=1680040971&sid=13&Fmt=2&clientId=1564&RQT=309&VName=PQD.
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Bennice, Chelsea O. "Altering life history traits a size-selective predator decreases the size of its prey. /." Connect to resource, 2008. http://hdl.handle.net/1811/32125.
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Spencer, Matthew. "The effects of habitat size on food web structure." Thesis, University of Sheffield, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.481753.
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Truemper, Holly A. "Food habits and prey size-selection of yellow perch in extreme southern Lake Michigan, with emphasis on the prey : round goby." Virtual Press, 2003. http://liblink.bsu.edu/uhtbin/catkey/1260485.
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Food habits for yellow perch Perca flavescens were compared using current and previous diet studies from southern Lake Michigan index sites. Yellow perch were not gape limited but size-selective in consumption of the newly established round goby Neogobius melanostomus. Ingested fish ranged from 7 to 47% of the yellow perch's total length and 2 to 53% of their gape. Currently, yellow perch diets are dominated in volume by fish/fish products (85%), which is double from previous studies. Utilization of zooplankton and insect prey items in the yellow perch diet has decreased to <1% by volume in 2002, contrasting with previous consumption of 4 to 20% and 5 to 17%, respectively, from previous studies during 1971-1993. Yellow perch are exhibiting opportunistic, generalist feeding strategy that incorporates both exotic and native prey items, allowing the population to use multiple prey items with the changing prey base in Lake Michigan.Department of Biology
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Rowlands, William Llewelyn. "Is prey selection in young gadoids in the Irish Sea limited by gape size or by the spectrum of prey available?" Thesis, University of Liverpool, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.406715.
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Adam, Peter James. "Morphological evolution in Cetacea skull asymmetry and allometry of body size and prey /." Diss., Restricted to subscribing institutions, 2007. http://proquest.umi.com/pqdweb?did=1375523531&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
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Wiersma, Jonathan H. "Maximum estimated bite force, skull morphology, and primary prey size in North American carnivores." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0014/MQ61307.pdf.
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Paul, Shubhabrata. "Prey-size selectivity in the bivalve Chione in the Florida Pliocene-Pleistocene : a re-evaluation." [Tampa, Fla] : University of South Florida, 2008. http://purl.fcla.edu/usf/dc/et/SFE0002740.
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Mascaro, Maite. "Crab foraging behaviour : prey size and species selection in Carcinus maenas (L.) and Cancer pagurus L." Thesis, Bangor University, 1998. https://research.bangor.ac.uk/portal/en/theses/crab-foraging-behaviour--prey-size-and-species-selection-in-carcinus-maenas-l-and-cancer-pagurus-l(402c594d-fe2f-42be-a39e-349cf07afff2).html.
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This thesis examines the foraging behaviour of Carcinus maenas and Cancerpagurus when presented with bivalves of contrasting morphology: Mytilus edulis, Ostrea edulis, Crassostrea gigas and Cerastoderma edule. Because foraging may be influenced by the relative abundance and morphological characteristics of both predator and prey, these aspects are also considered. Chelal size and strength of these crabs and prey shell shape largely determined handling techniques. When offered a size range of these bivalves individually, crabs attacked all encountered prey but rejected those that remained unbroken after several opening attempts, thus, emphasising the passive nature of their size-selective feeding. When offered paired combinations of mussels, oysters and cockles, larger crabs selected species in the ranked order of their profitability. Species-related preferences exhibited by crabs feeding on prey at or near the optimal size suggest that foraging decisions are partly based on evaluations of overall prey shape and volume, and that shell width constitutes an important feature which crabs recognise and associate with prey value. Variations in crab strength relative to size accounted for most intra-specific differences in foraging behaviour. Juvenile C maenas are limited in their choice of prey size, and are thus less species-selective. Adult C maenas are not so constrained, and exhibit a higher degree of species-selectivity. C. pagurus possesses powerful monomorphic chelae that operate at higher mechanical advantage than the cbelae of C maenas, and readily crushed larger mussels relative to their size. Differences in prey size selection between crab species varied with the species of prey offered, suggesting that certain shell features of these bivalves constitute effective barriers to even the powerful chelae of C pagurus. These results are relevant in the context of aquaculture, since predatory impact on commercially reared bivalves might be reduced by combining different prey species that offer predators alternative or preferred sources of food.
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Paul, Shubhabrata. "Prey-size selectivity in the bivalve Chione in the Florida Pliocene-Pleistocene: A reevaluation." Scholar Commons, 2008. https://scholarcommons.usf.edu/etd/445.
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Previous study of drilling predation on the bivalve Chione during the late Neogene of Florida suggested that prey-size selectivity of predators was disrupted by species turnover and morphological change within the prey genus. More recent experimental work, however, showed that at least some of these changes can be attributed to the confounding effects of facies shifts between naticid-dominated, muricid-dominated, and mixed predator assemblages. As muricids have the most abundant and continuous fossil record and are most responsible for predation on the Chione bivalve in modern benthic ecosystems of Florida, we use new criteria to isolate the muricid component of the Chione drillhole record and analyze the history of this type of predator independently. Our analysis, based on drilled Chione from four Plio-Pleistocene formations in Florida, does not support the previous scenario of disruption at the end of the Pliocene followed by predator recovery. Rather, selected prey size has steadily increased since the middle Pliocene, although the stereotypy of prey-size selection behaviors has decreased. In order to explain this trend, I performed a series of statistical analyses to explore factors most likely to have influenced muricid prey-size stereotypy. The timing of Species turnover within the prey lineage or change in prey phenotype does not correlate with the timing of changes in prey-size stereotypy and, therefore, cannot explain the observed changes in muricid behavior. Presence of secondary predators may also influence predator-prey interactions, because predators forage sub-optimally to ensure greater safety in the presence of enemies. Results indicate that secondary predation pressure decreased at the Caloosahatchee-Bermont boundary without any evident change in muricid prey-size stereotypy and hence refute the hypothesis that secondary predation induced sub-optimal foraging. A third factor tested is prey density, which plays a major role in predator-prey interactions in other systems by thwarting a predator's ability to single out the preferred individual prey. Increased Chione prey density correlates with and provides support for increased confusion among the muricid predators and hence driving the increased sub-optimal behavior reflected by the increased variability in prey-size selection. This is the first time prey density effect has been considered and its importance here over all other factors suggests that it may be a critical factor in short- and long-term predator behavior trends in fossil record.
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CORRÊA, Daniele Niedsberg. "Ecologia alimentar das serpentes semi-aquáticas Erythrolamprus jaegeri jaegeri (Günter, 1858) e Erythrolamprus poecilogyrus sublineatus (Cope, 1860) (Serpentes, Dipsadidae) na região costeira do extremo sul do Brasil." reponame:Repositório Institucional da FURG, 2014. http://repositorio.furg.br/handle/1/6031.
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Predadores exclusivamente carnívoros, as serpentes alimentam-se de presas variadas e ocupam diferentes hábitats. As adaptações evolutivas conferidas aos ofídios permitiram o desenvolvimento de múltiplos mecanismos de percepção da presa, modo de captura e estratégias que permitem a ingestão de presas bem maiores que seu próprio tamanho. Erythrolamprus jaegeri jaegeri e Erythrolamprus poecilogyrus sublineatus são serpentes semi-aquáticas que ocorrem em simpatria no extremo sul do Brasil. O presente estudo teve como objetivo analisar a composição da dieta dessas duas espécies e, mediante contrastes, investigar os fatores associados a essas diferenças. Para isso, foram utilizados exemplares provenientes da região de estudo, depositados em coleção Herpetológica da FURG (CHFURG). Os itens alimentares foram coletados, identificados ao menor nível taxonômico possível e medidos. Adicionalmente, todas as serpentes tiveram estruturas do corpo e da cabeça mensurados. Os itens alimentares foram analisados segundo métodos qualitativos e quantitativos como Frequência de Ocorrência (FO%), Abundância Numérica (N%), Análise Gravimétrica (P%) e Índice de Importância Relativa (IRI). Os itens mais importantes para ambas as espécies foram os anuros. Diferenças na composição da dieta e o índice de Levins indicaram um caráter especialista para E. j. jaegeri e generalista para E. p. sublineatus. E. p. sublineatus é estatisticamente maior do que E. j. jaegeri e se alimenta de itens maiores. Segundo as análises de regressão, as estruturas da cabeça parecem não interferir no tamanho das presas selecionadas, enquanto isso foi observada correlação positiva entre o comprimento e o peso de predadores e presas para as duas espécies. Os resultados indicaram que, apesar de simpátricas, a composição alimentar das espécies diverge segundo dois parâmetros: o tamanho do corpo do predador que está associado ao tamanho das presas selecionadas e a diferente amplitude de nicho de cada espécie, ambos permitindo que os recursos utilizados variem entre as espécies, diminuindo a competição e possibilitando a coexistência.
Exclusively carnivorous predators, snakes feed on various prey and occupy different habitats. The evolutionary adaptations conferred on snakes allows the development of multiple mechanisms that are the perception of the prey, capture mode and strategies that allow the ingestion of larger prey. Erythrolamprus jaegeri jaegeri and Erythrolamprus poecilogyrus sublineatus are semi-aquatic snakes which live on the extreme southern Brazil. This study aimed to compare the diet of these two species and also investigate the factors associated with these differences. To performes this study we use specimens from Herpetological Collection from FURG (CHFURG). Food items were collected, identified and measured, including snakes that had injured body structures. Food items were analyzed according to the qualitative and quantitative methods as Frequency of Occurrence (FO%), Numerical abundance (% N), Gravimetric Analysis (P%) and Index of Relative Importance (IRI). The most important prey for both species were anurans. The comparison of differences in the diet and the Levins index indicated that E. j. jaegeri is specialist and E. p. sublineatus is generalist. The bar graphs to the length and weight of the predators and prey showed that E. p. sublineatus is statistically larger than E. j. jaegeri and prey on larger animals. According the regressions analysis, the structures of the head do not seem to interfere with the size of the selected prey, meanwhile positive correlation was observed between the length and weight of predators and prey for both species. Results indicated that although sympatric, food species composition differs according to two parameters: the body size of the predator that is associated with the size of the selected prey and different range of each species niche, allowing both the resources used to vary between species, reducing competition and allowing coexistence.
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Hammerschlag-Peyer, Caroline M. "The Influence of Body Size on the Ecology of Coastal Fish Predators in The Bahamas." FIU Digital Commons, 2011. http://digitalcommons.fiu.edu/etd/502.
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Body size is a fundamental structural characteristic of organisms, determining critical life history and physiological traits, and influencing population dynamics, community structure, and ecosystem function. For my dissertation, I focused on effects of body size on habitat use and diet of important coastal fish predators, as well as their influence on faunal communities in Bahamian wetlands. First, using acoustic telemetry and stable isotope analysis, I identified high variability in movement patterns and habitat use among individuals within a gray snapper (Lutjanus griseus) and schoolmaster snapper (L. apodus) population. This intrapopulation variation was not explained by body size, but by individual behavior in habitat use. Isotope values differed between individuals that moved further distances and individuals that stayed close to their home sites, suggesting movement differences were related to specific patterns of foraging behavior. Subsequently, while investigating diet of schoolmaster snapper over a two-year period using stomach content and stable isotope analyses, I also found intrapopulation diet variation, mostly explained by differences in size class, individual behavior and temporal variability. I then developed a hypothesis-testing framework examining intrapopulation niche variation between size classes using stable isotopes. This framework can serve as baseline to categorize taxonomic or functional groupings into specific niche shift scenarios, as well as to help elucidate underlying mechanisms causing niche shifts in certain size classes. Finally, I examined the effect of different-sized fish predators on epifaunal community structure in shallow seagrass beds using exclusion experiments at two spatial scales. Overall, I found that predator effects were rather weak, with predator size and spatial scale having no impact on the community. Yet, I also found some evidence of strong interactions on particular common snapper prey. As Bahamian wetlands are increasingly threatened by human activities (e.g., overexploitation, habitat degradation), an enhanced knowledge of the ecology of organisms inhabiting these systems is crucial for developing appropriate conservation and management strategies. My dissertation research contributed to this effort by providing critical information about the resource use of important Bahamian fish predators, as well as their effect on faunal seagrass communities.
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McDonald, Paul, and Paul McDonald@latrobe edu au. "Reproductive success, dimorphism and sex allocation in the brown falcon Falco berigora." The Australian National University. Faculty of Science, 2003. http://thesis.anu.edu.au./public/adt-ANU20041111.100436.
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This project describes various aspects of the breeding ecology and behaviour of the brown falcon Falco berigora, a common but poorly study Australian raptor. In particular it examines (a) the main influences on reproductive success; (b) tests predictions of theories proposed to explain the evolution and maintenance of sexual size dimorphism (RSD; females the larger sex) in raptors; and (c) investigates sex allocation patterns in the light of current sex ratio and parental investment theory. The study was conducted between July 1999 and June 2002 approximately 35 km southwest of Melbourne, at the Western Treatment Plant (WTP), Werribee (38°0S 144°34E) and surrounds, a total area of approximately 150 km2.¶
· In all plumage and bare part colouration of 160 free-flying falcons was described. The majority of variation in these characters could be attributed to distinct age and/or sex differences as opposed to previously described colour morphs.¶
· Nestling chronology and development is described and formulae based on wing length derived for determining nestling age. An accurate field-based test for determining nestling sex at banding age is also presented.¶
· Strong sex role differentiation was apparent during breeding; typical of falcons females performed most parental duties whilst males predominantly hunted for their brood and partner. Based on observations of marked individuals, both sexes of brown falcons aggressively defended mutual territories throughout the year, with just 10% of each sex changing territories during the entire study period. Males performed territorial displays more frequently than females, the latter rarely displaying alone.¶
· The diet of the population as a whole was very broad, but within pairs both sexes predominantly specialised on either lagomorphs, small ground prey (e.g. house mice Mus musculus), small birds, large birds or reptiles, according to availability.¶
· Reproductive parameters such as clutch size and the duration of parental care were constant across all years, however marked annual differences in brood size and the proportion of pairs breeding were evident.¶
· Age was an important influence upon reproductive success and survival, with immature birds inferior to adults in both areas. However, interannual differences were by far the most influential factor on breeding success and female survival. Heavy rain downpours were implicated as the main determinant of reproductive success and adult female mortality in a population largely devoid of predation or human interference.¶
· Female-female competition for territorial vacancies was intense; larger adult females were more likely to be recruited and once breeding fledged more offspring. In contrast, male recruitment and breeding success was unrelated to either body size or condition indices, although smaller immature males were more likely to survive to the next breeding season. This directional selection is consistent only with the predictions of the intrasexual competition hypothesis.¶
· Despite marked RSD (males c. 75% of female body mass), throughout the nestling phase female nestlings did not require greater quantities of food than their male siblings. However, female parents fed their last-hatched sons but not daughters, resulting in the complete mortality of all last-hatched female offspring in focal nests. Given last-hatched nestlings suffered markedly reduced growth rates and female, but not male, body size is important in determining recruitment patterns, the biased allocation amongst last-hatched offspring is likely to reflect differing benefits associated with investing in small members of each sex, consistent with broad-scale Trivers-Willard effects. Recruitment patterns support this, with surviving last-hatched females, in contrast to males, unable to gain recruitment into the breeding population upon their return to the study site.¶
Thus selection appears to act at the nestling, immature and adult stages to maintain RSD in the focal population. Larger females were favoured in the nestling phase, at recruitment and once breeding had greater reproductive success. In contrast, selection favoured a reduction or maintenance of immature male size as smaller birds had a greater chance of survival in the year following recruitment than their larger counterparts; thereafter male size was unimportant. Together, this directional selection favouring increased female competitive ability is consistent only with the predictions of the intrasexual competition hypothesis, which appears the most probable in explaining the maintenance and perhaps evolution of RSD in raptors.
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Anderson, Eric S. "The Response of a Predatory Fish, Ophiodon elongatus, to a Marine Protected Area: Variation in Diet, Catch Rates, and Size Composition." DigitalCommons@CalPoly, 2016. https://digitalcommons.calpoly.edu/theses/1679.
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Marine Protected Areas (MPAs) are a management tool used to protect and sustain many ecologically and economically important fish species from overexploitation by recreational and commercial fishing. Lingcod (Ophiodon elongatus) and some of its prey species, such as rockfish (Sebastes spp.), are species that are protected from fishing in some California MPAs. Lingcod is an apex predator that consumes a variety of fish and invertebrate species. In this study, I sought to assess the effect of an MPA on the abundance, size and diet of Lingcod. I hypothesized that Lingcod in a no-take MPA would be more abundant and larger than Lingcod in an adjacent reference site (REF) that was open to fishing. Furthermore, I hypothesized that diet would differ between Lingcod in caught the MPA and Lingcod in the REF. I collected Lingcod from the Point Buchon State Marine Reserve (MPA) and an adjacent REF site that was open to fishing. I measured, weighed, sexed, and collected stomach contents from Lingcod using the gastric lavage (stomach pumping) technique. Then, I identified prey items from Lingcod stomach contents down to the lowest taxonomic level possible and quantified diet composition by percent by occurrence, percent by number, and percent by mass. Lingcod in the MPA consumed more fish prey items than Lingcod in the REF site. Lingcod in the REF consumed more cephalopod prey items than Lingcod in the MPA. I analyzed the four most common prey items (rockfish, anchovies, flatfish, and octopus) for nutritional content. My data suggest that Lingcod increased in size and abundance in a no-take MPA because they do not suffer from fishing mortality. However, a more nutritious diet could also contribute to a biologically significant advantage for Lingcod in the MPA. To address this would require further research focused on calculating the net energy (gross energy extracted from the prey item minus the energetic costs of handling and digesting the prey item) obtained by Lingcod from consuming different fish and cephalopod prey items. MPAs can be an effective management tool for protecting fish stocks, although, it is important to understand the interspecific interactions between predator and prey species to adaptively mange MPAs and the species that reside within them.
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Spjern, Victor. "Hur påverkar storskarv (Phalacrocorax carbo) och skäggdopping (Podiceps cristatus) fisksamhället i grunda, näringsrika sjöar?" Thesis, Linköpings universitet, Biologi, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-166546.
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Piscivorous birds are an integrated part of lake and coastline ecosystems. Despite decades of research it is yet unclear what influence fish eating birds have on the fish community. The aim of this literature study was to focus on how two fish eating birds, Great Cormorant and Great Crested Grebe, influence the fish community in shallow and eutrophic lakes. Different types of analysis methods have been used when doing research on the subject, including pellet analysis, stomach content analysis, tagging of fishes by “PIT”-techniques and analysis by observation. Results show that conclusions by studies tend to vary, but generally higher bird density, lower water temperature and a relatively high turbidity contribute to a higher influence on the fish community. Both bird species are opportunistic in their choice of food and catch prey of the species that occur locally. Both species also limit themselves in the prey size, but the choice vary over seasons because of water temperature and the birds requirements in association with breeding and migration. The significant level of influence seems to be when predation is conducted on younger and smaller fishes. The influence on the fish size can also be indirect, where predation on smaller individuals prevent fishes from becoming older and bigger. As studies tend to deviate in conclusion, no general answer to this issue can be given at present. Comprehensive research with several years of full control over both fish-and bird population is needed to find the proper conclusion.
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Eklöv, Peter. "Effects of behavioural flexibility and habitat complexity on predator-prey interactions in fish communities." Doctoral thesis, Umeå universitet, Ekologi och geovetenskap, 1995. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-101769.
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Leonardsson, Kjell. "Variation in age and size at maturation in two benthic crustaceans in the Gulf of Bothnia." Doctoral thesis, Umeå universitet, Ekologi och geovetenskap, 1990. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-100708.
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The thesis deals with variation in age and size at maturation in Saduria entomon and Pontoporeia affinis along a depth gradient in the Gulf of Bothnia, Sweden. I have analysed at what sizes and ages animals should mature in relation to growth and mortality conditions. The thesis also deals with predator-prey interactions within and between the two species. The isopod Saduria entomon matured during winter at an age of three years at 5 m depth in the Norrby archipelago (63° 30'N, 19° 50'E). Males matured eariier and at larger sizes (27-48 mm) than females (23-36 mm). The offspring were released in early summer. The adult size increased with increasing depth. Outside the archipelago, at 125 m depth, the sexes reached a size of 84 and 54 mm respectively. No evidence for temporal restriction in the release of the young was found at the deep area. The species was shown to have a high capacity for cannibalism on small conspecifics, although the small ones have the potential to avoid aggregations of large conspecifics. The number of small conspecifics eaten was related both to the absolute and relative densities of the alternative prey Pontoporeia affinis. The cannibalistic behaviour have the potential to act as a stabilizing mechanism in the Saduria-Pontoporeia system. Fourhom sculpin (Myoxocephalus quadricornis) was the fish species of utmost importance as a predator on S.entomon, and it mainly preferred large specimens. The amphipod Pontoporeia affinis matured at an age of two years in the littoral zone and at a very deep (210 m) locality. Between these depths it mainly reached maturation at an age of three years. In some years in densely populated areas, they delayed reproduction another year and reproduced as four year old. The variation in age at maturation in P.affinis in relation to depth could be quantitatively predicted by maximizing fitness in the Euler-Lotka equation. The size variation at maturation in S.entomon could be qualitatively predicted by maximizing fitness in the Euler-Lotka equation. The general condition for a smaller size at maturity to be adaptive at high temperatures (i.e. shallow areas) is that mortality rate should increase faster than growth rate with increasing temperature. When mortality is higher in young stages than in older and larger ones the pattern is also predicted when growth increases faster than mortality. Small animals may prefer warmer habitats than large ones, because of the presence of a size dependent trade-off between temperature induced growth and mortality. More exactly, the optimum solution of the trade-off between growth and mortality in hazardous environments was suggested to approach maximization of the expression s(W+g)/W, where s is survival rate, W is body weight, and g is growth rate.Diss. (sammanfattning) Umeå : Umeå universitet, 1990, härtill 6 uppsatser
digitalisering@umu
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Andersson, Emma. "Adaptive trait utility in the feeding apparatus of European whitefish (Coregonus lavaretus) : Relationships between feeding morphology and maximum and minimum prey size in the diet of whitefish." Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-104986.
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Whitefish (Coregonus lavaretus) populations diverge into morphs that differ in body size along a benthic-limnetic axis and throughout the depth of the water column. This process is assumedly initiated by the presence of northern pike (Esox lucius) and is followed by morphological adaptations to available food resources. In this study eight populations of whitefish was studied with the purpose of increasing the knowledge about adaptive trait utility in the feeding apparatus of whitefish. This was done by analyzing the mean and absolute maximum and minimum prey size ingested by fish along four morphological trait gradients. The morphological traits was body size, gill raker number and density, and gape size. The results show clear evidence of morphological adaptations in both the benthic and limnetic habitat, furthermore, when comparing the two prey size responses (mean and absolute values) it becomes clear that none of the studied whitefish is physically constrained in terms of the largest prey they can ingest. However, large fish seem to be limited in eating small prey sizes. Interestingly, I also found strong indicators for filter feeding adaptation for one of the studied populations.
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Hill, Jennifer Marie. "Predator biomass and habitat characteristics affect the magnitude of consumptive and non-consumptive effects (NCEs): experiments between blue crabs, mud crabs, and oyster prey." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41172.
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Recent research has focused on the non-lethal effects of predator intimidation and fear, dubbed non-consumptive effects (NCEs), in which prey actively change their behavior and habitat use in response to predator chemical cues. Although NCEs can have large impacts on community structure, many studies have ignored differences in predator population structure and properties of the natural environment that may modify the magnitude and importance of NCEs. Here, I investigated the roles of predator size and density (i.e. biomass), as well as habitat characteristics, on predator risk assessment and the magnitude of consumptive and NCEs using blue crabs, mud crabs, and oyster prey as a model system. Predation experiments between blue crabs and mud crabs demonstrated that blue crabs consume mud crabs; however, the consumptive effects were dependent upon blue crab body size and habitat type. When mud crabs were exposed to chemical cues from differing biomasses of blue crabs in laboratory mesocosms, mud crab activity and predation on oysters was decreased in response to high biomass treatments (i.e. large and multiple small blue crabs), but not to low biomass predators (i.e single small blue crab), suggesting that risk associated with predator size is perceptible via chemical cues and is based on predator biomass. Further experiments showed that the perception of risk and the magnitude of the NCEs were affected by the sensory cues available and the diet of the blue crab predator. The NCE based on blue crab biomass was also demonstrated in the field where water flow can disperse cues necessary for propagating NCEs. Properties of water flow were measured within the experimental design and during the experiment and confirmed cage environments were representative of natural conditions and that patterns in NCEs were not associated with flow characteristics. These results affect species conservation and commercial fisheries management and demonstrate that we cannot successfully predict NCEs without considering predator size structure and the contexts under which we determine predator risk.
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Ribeiro, Sara Pacheco. "Estudo dos efeitos de alterações climáticas nas interações bióticas em ambientes aquáticos." Master's thesis, Universidade de Évora, 2019. http://hdl.handle.net/10174/26431.
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Climate change is currently one of the major environmental changes that dramatically affect life on Earth. A key gap in knowledge is how environmental change modifies species interactions and its consequences. The present dissertation reports a study on how predator-prey interactions in aquatic systems change across different sites in the Iberian Peninsula. The different interaction pairs were tested under two different temperatures at six locations through a heating system. The results showed that the functional responses at ambient temperature are significant, in which the prey consumption rates were dependent of prey density in all sites, increasing with higher density levels. The opposite was verified in half of the sites under induced temperature. Understanding how ecosystems respond to current and future climatic changes is essential to provide the basis for conservation measures that ensure the long-term persistence of biodiversity; Resumo:
As alterações climáticas são atualmente uma das principais alterações ambientais que afeta drasticamente a vida na Terra. Há ainda lacunas de conhecimento no modo como o aquecimento afeta as interações bióticas. A presente dissertação versa sobre as mudanças nas interações predador-presa em sistemas aquáticos em diferentes regiões da Península Ibérica. Diferentes pares de interação foram testados a duas temperaturas em seis locais distintos, recorrendo a um sistema de aquecimento. Os resultados mostraram que as respostas funcionais são significativas sob temperatura ambiente, na qual as taxas de consumo de presas foram dependentes da densidade das mesmas em todos os locais, aumentando com níveis de densidade superiores. O contrário foi verificado em metade dos locais sob temperatura induzida. Compreender como os ecossistemas naturais respondem às alterações climáticas atuais e futuras é essencial para fornecer a base para medidas de conservação que assegurem a persistência da biodiversidade a longo prazo.
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Matott, Michael. "An Examination of Modulation of Feeding Behavior in the Nurse Shark Ginglymostoma cirratum (Bonaterre 1788)." [Tampa, Fla. : s.n.], 2003. http://purl.fcla.edu/fcla/etd/SFE0000106.
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Reisinger, Ryan Rudolf. "Abundance and predatory impact of killer whales at Marion Island." Diss., University of Pretoria, 2011. http://hdl.handle.net/2263/27643.
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Killer whales are the oceans’ apex predator and are known to have important effects on ecosystems. At Subantarctic Marion Island, southern Indian Ocean, they have only been studied opportunistically, resulting in limited knowledge of their ecosystem impact here. This dissertation describes the prey and seasonal abundance, estimates the population size and assesses the predatory impact of killer whales on seals and penguins at Marion Island, using dedicated and opportunistic shore-based observations and photographic identification, from 2006 to 2009. During 823 sightings of killer whales at Marion Island (2006 to 2009) 48 predation events were recorded; in only 10 cases could prey be identified. Killer whales fed on fur seals, elephant seals and penguins. Constant effort (dedicated) observations (259 hours, 2008 to 2009) showed that killer whale abundance, which peaked in September to December with a secondary peak in April to May, is linked to the abundance of seals and penguins. Mark-recapture analyses were performed using nearly 10 000 photographs taken from 2006 to 2009. Following careful quality control criteria 37 individuals were identified and a population size of 42 (95% CI = 35-50) individuals estimated using the open population POPAN parameterization in the software program MARK. The analytical approach is more rigorous than that used in any previous population size assessment at Marion Island. Finally, the above data were integrated to assess whether top-down control of seal and penguin populations at Marion Island is generally plausible using a simple process of elimination. Based on published data I predicted the energetic ingestion requirements of adult male and female killer whales as 1 394 MJ.day-1 and 1 028 MJ.day-1, respectively. Expanding these requirements to the 37 killer whales photographically identified at Marion Island, the population requires 40 600MJ.day-1. Based on available energy density and mass data, I predicted the energy content of available seal and penguin prey and calculated the rates at which killer whales would consume these prey in various scenarios. Penguins and Subantarctic fur seals are relatively insensitive to killer whale predation owing to their large population sizes (10 000s to 100 000s), conversely, the smaller populations (100s to 1 000s) of Antarctic fur seals and southern elephant seals are sensitive to predation, particularly the latter as they have a high energy content (approximately 2 000 to 9 000 MJ). Populations of these seals are currently increasing or stable and I conclude that presently killer whale predation is not driving population declines, although they clearly have the potential for regulation of these smaller populations. Thus, if population sizes were reduced by bottom-up processes, if killer whale diet shifted, or if prey availability changed, top-down control by killer whales could become significant. This study provides baseline information for the informed management and conservation of killer whales at Marion Island, identifies avenues for further research, and provides a foundation for the continuation of structured and dedicated killer whale research at Marion Island.Dissertation (MSc)--University of Pretoria, 2011.
Zoology and Entomology
unrestricted
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Metz, Tasha Lynn. "Factors influencing Kemp's ridley sea turtle (Lepidochelys kempii) distribution in nearshore waters and implications for management." Texas A&M University, 2004. http://hdl.handle.net/1969.1/1247.
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Post-pelagic juvenile and subadult Kemp's ridley sea turtles (Lepidochelys kempii) (20-40 cm straight carapace length) utilize nearshore waters of the northwestern Gulf of Mexico as nursery or developmental feeding grounds. This study utilizes 10 years of entanglement netting data to characterize long-term abundance and distribution of Kemp's ridley sea turtles at index habitats in this region. Netting surveys were conducted during April-October 1993-2002, primarily at Sabine Pass, Texas and Calcasieu Pass, Louisiana. Additionally, this study takes an ecosystem-based approach to understanding factors influencing Kemp's ridley in-water abundance and distribution via the development of a conceptual model incorporating data on nesting dynamics, environmental conditions, prey availability, and predation pressure.
Overall monthly mean ridley catch-per-unit-effort (CPUE) peaked in the beginning of summer (April-June), probably in response to rising water temperatures and seasonal occurrence of blue crab prey. Annual mean ridley CPUE across all study areas peaked in 1994, 1997, 1999 and 2002, suggesting a 2-3 year cycle in abundance that may be related to patterns in clutch size or hatch success at the Rancho Nuevo, Mexico nesting beach. However, ridley CPUE in nearshore waters remained relatively constant or decreased slightly even as number of hatchlings released from Rancho Nuevo increased exponentially. Annual declines in Texas strandings since 1994 and subsequent increases in Florida counterparts since 1995 suggest a shift in ridley distribution from the western to eastern Gulf in recent years.
Significant declines in ridley CPUE at Sabine Pass since 1997 coincided with a concurrent reduction in blue crab size, but a similar trend was not detected at Calcasieu Pass. Kemp's ridley occurrence at study sites was not significantly related to shrimping activity/by-catch. There also were no biologically significant relationships between Kemp's ridley CPUE and abiotic factors, nor were ridleys deterred from utilizing areas frequented by bull sharks. Overall, nesting dynamics and prey availability were conceptual model components appearing to have the greatest influence on nearshore ridley occurrence.
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Little, Charlene Knight. "Decreasing Surgical Site Infections in Vascular Surgery Patients." ScholarWorks, 2016. https://scholarworks.waldenu.edu/dissertations/2412.
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Postoperative surgical site infections are common complications in the operating room. Infections prolong hospital stays, heighten costs, and increase morbidity and mortality. The purpose of this evidence-based quality improvement project was to develop policy, program, and practice guidelines to prevent surgical site infections in vascular surgery patients. Rosswurm and Larrabee's change model was used to develop materials using the best evidence for the recommended practice changes. The Plan, Do, Check, Act model was selected to guide quality improvement. The project goal was to decrease the surgical site infection rate to below the national average. Products of the project include policy, protocol, and practice guidelines developed based on recommended practices of the Association of periOperative Registered Nurses and current peer-reviewed literature. An interdisciplinary project team of institutional stakeholders was used to insure context-relevant operationalization of the evidence in practice. The team was assembled, led in a review of relevant literature, and convened regularly until project products were finished. Three scholars with expertise in the content area were then identified by the project team and asked to validate the content of developed products. Products were revised according to expert feedback. Implementation and evaluation plans were developed by the project team to provide the institution with all necessary process details to carry out the practice change. The evaluation plan advises using a retrospective chart review to compare rates of infection between patients receiving chlorhexidine skin preparation with showers and preoperative chlorhexidine cloths alone. A positive outcome could contribute to positive social change by decreasing preventable infections.
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ANDO, Hideki, and Yusuke TANAKA. "Register File Size Reduction through Instruction Pre-Execution Incorporating Value Prediction." Institute of Electronics, Information and Communication Engineers, 2010. http://hdl.handle.net/2237/14941.
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Lima, Ariane Furtado de. "Alimentação inicial do Jundiá, Rhamdia voulezi Haseman 1911: efeitos da privação alimentar sobre o crescimento e padrões na seleção de presas ao longo do período larval." Universidade Estadual do Oeste do Parana, 2013. http://tede.unioeste.br:8080/tede/handle/tede/1917.
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The effects of feeding privation on growth of larvae of jundiá Rhamdia voulezi as well as the feeding preference during larval period were evaluated. For this purpose two experiments were conducted which began soon after complete absorption of the yolk sac, the fourth day after hatching (DAH). The feeding privation experiment was performed in 8 treatments consisting of different diets, including the control treatment (CT) in which there was no food supply. The food was provided for the first time in the 4th, 5th, 6th, 7th, 8th, 9th and 10th DAH corresponding to treatments: T4, T5, T6, T7, T8, T9 and T10, respectively. The food consisted of zooplankton and newly hatched artemia. We performed 3 trials of selectivity to analyze the feeding preference throughout the larval period, comprising different larval stages and classes of standard length. In this, the larvae were fed exclusively on zooplankton collected from fish ponds. The results demonstrated that the larvae fed on the fourth to sixth DAH had a significantly higher growth than those fed later, from the seventh DAH. The point of no return was recorded in the same period in the 7th DAH. With respect to feeding selectivity, there were variations in the patterns of prey selection in different days of life analyzed. Initially on the 5th DAH, preflexion stage, larvae strongly selected rotiferas (unidentified) and cladocerans (Diaphanosoma spinulosum, D. brevireme, Moina sp., M. micrura, M. minuta). In the remaining days of life examined, the cladocerans continued to be strongly selected. However on the 8th DAH, flexion stage, they selected less intensely the copepods Argyrodiaptomus azevedoi and Termocyclops decipiens and more strongly A. furcatus, Notodiaptomus spinuliferus and Metacyclops mendocinus at 10 DAH, postflexion stage. The delay of the first feeding drastically affected the growth of the larvae, and that if feeding is started before the point of no return there are chances of recovery. So, it is important to have suitable availability of food, with a variety of type and size so that they can compensate for the morphological limitations of larvae in the early of their development. Concomitant to its growth, the larvae tend to specialize in certain prey items. The size of prey consumed is related to the size of the larvae and the gape size. Initially larvae have a preference for smaller prey, rotifers and cladocerans, and later when they are more developed prefer to feed on larger prey, the copepods.
Neste estudo foram avaliados os efeitos da privação alimentar sobre o crescimento das larvas de jundiá Rhamdia voulezi bem como a preferência alimentar durante o período larval. Para isto foram realizados dois experimentos que tiveram início logo após a absorção completa do saco vitelínico, que ocorreu no 4o dia após a eclosão (DAE). O primeiro experimento de privação alimentar foi realizado com 8 tratamentos constituídos por diferentes regimes alimentares, incluindo o tratamento controle (TC) no qual não houve fornecimento de alimento. O alimento foi fornecido pela primeira vez no 4o, 5o, 6o, 7o, 8o, 9o e 10o DAE, correspondendo aos tratamentos: T4; T5, T6, T7, T8; T9 e T10, respectivamente. A alimentação consistiu de zooplâncton e artêmia recém-eclodida. Para avaliar a preferência alimentar, foram realizados 3 ensaios de seletividade alimentar ao longo de todo o período larval, compreendendo diferentes estágios de desenvolvimento e classes de comprimento padrão. Neste, as larvas foram alimentadas exclusivamente com zooplâncton coletado de tanques de cultivo. Os resultados demonstraram que as larvas de jundiá que receberam alimento do 4o ao 6o DAE tiveram desenvolvimento significativamente maior que aquelas alimentadas mais tardiamente, a partir do 7o DAE. O ponto de não retorno foi registrado neste mesmo período, no 7o DAE. Com relação à seletividade alimentar, houve variações nos padrões de seleção de presas nos diferentes dias de vida analisados. Inicialmente no 5o DAE, estágio de pré-flexâo, as larvas selecionaram fortemente os rotiferas (não identificados) e os cladoceras (Diaphanosoma spinulosum, D. brevireme, Moina sp., M. micrura, M. minuta). Nos demais dias de vida analisados, os cladoceras continuaram a ser fortemente selecionados. Entretanto no 8o DAE, estágio de flexão, selecionaram menos intensamente os copepodas Argyrodiaptomus azevedoi e Termocyclops decipiens e no 10o DAE, estágio de pós-flexão, consumiram especialmente Argyrodiaptomus furcatus, Notodiaptomus spinuliferus e Metacyclops mendocinus. Conclui-se que o retarde da primeira alimentação afeta drasticamente o crescimento das larvas, e que, se a alimentação for iniciada antes do ponto de não retorno há chances de recuperação e sobrevivência larval. Para isto, é importante que haja disponibilidade adequada de alimento, com variedade de tipo e de tamanho de modo que possam compensar as limitações morfológicas das larvas no início do seu desenvolvimento. Concomitante ao seu crescimento, as larvas tendem a se especializar em determinados itens presa, existindo uma seleção de presas tanto pelo tipo como também pelo tamanho, onde o tamanho da presa consumida está relacionado com o tamanho da larva e o tamanho de sua boca. Inicialmente as larvas de jundiá têm preferência por itens presas menores, os rotíferos e cladoceras, posteriormente, quando estão mais desenvolvidas, preferem alimentar-se de presas maiores, os copepodas.
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Tanaka, Yusuke, and Hideki Ando. "Reducing register file size through instruction pre-execution enhanced by value prediction." IEEE, 2009. http://hdl.handle.net/2237/13892.
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Bokach, Matthew John. "The relative influences of predation and prey availability on ardeid breeding colony site selection." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0009586.
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Luukkonen, B. G. Mattias. "Splice site selection in Saccharomyces cerevisiae pre-mRNA splicing /." Stockholm, 1998. http://diss.kib.ki.se/1998/91-628-2872-X.
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Merry, J. C. "The effects of droplet size and application method on the activity of pre-emergence hebicides." Thesis, Imperial College London, 1986. http://hdl.handle.net/10044/1/38103.
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Milne, Susan Brooke. "Pre-Dorset lithic technology, a study of lithic assemblage variability in an inland Pre-Dorset site." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ40482.pdf.
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Nobre, Marlita Figueirinhas. "Produção de pão a partir de farinhas estremes de aveia." Master's thesis, ISA, 2014. http://hdl.handle.net/10400.5/6807.
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Mestrado em Engenharia Alimentar - Processamento dos Alimentos - Instituto Superior de AgronomiaThe food market has been experiencing a growing demand for healthy bread in response to related needs. The present work aims to be a contribution to this topic by the production of pure oat flour bread having in mind its nutritional and bioactive components. Aiming to optimize the characteristics of the product, the effects of the flour particle size, physical pre-treatments (extrusion-cooking and steaming), action of different emulsifiers and fermentation time were studied. For bread production the flour hydration degree was determined using the Brabender Farinograph. All the produced breads were evaluated in terms of volume, texture and organoleptic assessment. It was found that the flour particle size affected the hardness and the density of the breads. Those that were produced with the coarser flour were those showing the higher values. The pre-treatments exerted negative effects. With regard to the emulsifiers, the sodium stearoyl-2-lactylate (SSL) stood out positively. Combining these results with the fermentation times, it was concluded that the bread presenting better characteristics was the one produced with the coarser flour (2mm), without neither any physical treatment nor addition of emulsifiers, proofed for 30 minutes. Thus, it is feasible to produce oat bread. It should be remarked that the found results may be improved namely by changing the hydration degree or using other technological aids.
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Irshad, Muhammad Aatif. "The effect of prior austenite grain size on the machinability of a pre-hardened mold steel. : Measurement of average grain size using experimental methods and empirical models." Thesis, Karlstads universitet, Avdelningen för maskin- och materialteknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-8777.
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The use of pre-hardened mold steels has increased appreciably over the years; more than 80% of the plastic mold steels are used in pre-hardened condition. These steels are delivered to the customer in finished state i.e. there is no need of any post treatment. With hardness around ~40HRC, they have properties such as good polishability, good weldability, corrosion resistance and thermal conductivity. Machinability is a very important parameter in pre-hardened mold steels as it has a direct impact on the cost of the mold. In normal machining operations involving intricate or near net shapes, machining constitutes around 60% of the total mold cost. Efforts are underway to explore every possible way to reduce costs associated with machining and to make production more economical. All the possible parameters which are considered to affect the machinability are being investigated by the researchers. This thesis work focuses on the effect of prior austenite grain size on the machinability of pre-hardened mold steel (Uddeholm Nimax). Austenitizing temperatures and holding times were varied to obtain varying grain sized microstructures in different samples of the same material. As it was difficult to delineate prior-austenite grain boundaries, experimental and empirical methods were employed to obtain reference values. These different grain sized samples were thereafter subjected to machining tests, using two sets of cutting parameters. Maximum flank wear depth=0.2mm was defined for one series of test which were more akin to rough machining, and machining length of 43200mm or maximum wear depth=0.2mm were defined for second series of tests which were similar to finishing machining. The results were obtained after careful quantative and qualitative analysis of cutting tools. The results obtained for Uddeholm Nimax seemed to indicate that larger grain sized material was easier to machine. However, factors such as retained austenite content and work hardening on machined surface, which lead to degradation of machining operations were also taken into consideration. Uddeholm Nimax showed better machinability in large grained samples as retained austenite(less than 2%) content was minimal in the large grained sample. Small grained sample in Uddeholm Nimax had a higher retained austenite (7+2%) which resulted in degradation of machining operation and a lesser cutting tool life.
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Wong, Edric, Jason Clonts, Kathryn Matthias, and Brian Erstad. "Evaluation of Timing of Vancomycin Surgical Site Infection Prophylaxis with Scheduled Antibiotic." The University of Arizona, 2012. http://hdl.handle.net/10150/614460.
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Class of 2012 AbstractSpecific Aims: The primary purpose of this study was to evaluate the time of vancomycin pre-operative surgical site infection prophylaxis administration relative to other scheduled antibiotic therapy at a tertiary care, academic medical center. The secondary purpose was to characterize the incidence of adverse events post-surgery that were associated with vancomycin therapy in patients who received both pre-operative scheduled vancomycin therapy and vancomycin for surgical site infection prophylaxis Methods: This descriptive study was a retrospective medical chart review of all patients over the age of 28 days who received vancomycin for surgical site infection prophylaxis between February 2011 and May 2011 at a tertiary care, academic medical center. This study was approved be the Institutional Review Board. The subject population included patients admitted to the hospital for at least 72 hours who received at least 48 hours of scheduled vancomycin (IV), daptomycin or linezolid therapy before index surgery and subsequently received surgical site infection prophylaxis with vancomycin. Main Results: Of the 20 subjects who meet the study inclusion criteria, 18 (90%) subjects received scheduled vancomycin doses within 48 hours prior to surgery, 5 (25%) subjects within 4 hours, and 4 (20%) subjects within 2 hours. No surgical site infections were reported. Conclusions: This was a pilot study to evaluate the timing of vancomycin surgical site infection prophylaxis doses with scheduled vancomycin, linezolid, and daptomycin. No adverse effects associated with surgical site infection prophylaxis were reported but the sample size is small and likely inadequate to detect this potential issue.
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Macías, Ribela Sara. "Mechanism of regulation of the RPL30 pre-mRNA splicing in yeast." Doctoral thesis, Universitat Pompeu Fabra, 2008. http://hdl.handle.net/10803/7112.
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The mechanisms of pre-mRNA splicing regulation are poorly understood. Here we dissect how the Saccharomyces cerevisiae ribosomal L30 protein blocks splicing of its pre-mRNA upon binding a kink-turn structure including the 5' splice site. We show that L30 binds the nascent RPL30 transcript without preventing recognition of the 5' splice site by U1 snRNP but blocking U2 snRNP association with the branch site. Interaction of the factors BBP and Mud2p with the intron, relevant for U2 snRNP recruitment, is not affected by L30. Furthermore, the functions of neither the DEAD-box protein Sub2p in the incipient spliceosome, nor of the U2 snRNP factor Cus2p on branch site recognition, are required for L30 inhibition. These findings contrast with the effects caused by binding a heterologous protein to the same region, completely blocking intron recognition. Collectively, our data suggest that L30 represses a spliceosomal rearrangement required for U2 snRNP association with the nascent RPL30 transcript.
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Schmidt, Róbert. "Porovnanie implementácie Business Intelligence pomocou open source riešení pre stredne veľké spoločnosti." Master's thesis, Vysoká škola ekonomická v Praze, 2016. http://www.nusl.cz/ntk/nusl-261779.
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The main goal of master thesis is to analyze and propose possible low cost Business Intelligence solution with open source technologies and comparison of available tools for implementation in middle size company. We compare Pentaho and Jaspersoft tools implemented on local hardware and cloud environment with Microsoft Azure services. The theoretical part focuses mainly on understanding the business intelligence and its architecture, because architecture is an important part of the work. Actual tools are designed as stand alone modules for specific activities in the business intelligence lifecycle. Low cost tools are often connected with open source technologies and cloud computing. This part of the work contains explanation of these terms and their advantages and disadvantages for our chosen target group of companies. The analytical part includes defined parameters by which it is conducted analysis of tools and their comparison. Business Intelligence solutions are divided according to arcitectural layers. The evaluation criteria are divided into financial, technical and user category. In conclusion, chosen tools are compared and evaluated. The main contribution of this thesis is comparison of open source business intelligence tools for implementation in middle size company. According to the EU directive, middle size company does not exceed 250 employees or profit is less than 50 million euros. The reader can compare the different solutions and their pitfalls or shortcomings that could be critical for the implementation.
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Estibeiro, J. Peter. "Factors involved in 3' splice site selection in eukaryotic pre-messenger RNA." Thesis, University of Leicester, 1987. http://hdl.handle.net/2381/35213.
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The work presented in this thesis is an investigation of factors involved in 3' splice site selection. To try to determine the intrinsic strengths of 3' splice site sequences, a cis-competition assay system was used. This system was based on the large intervening sequence (IVS-2) of the rabbit beta-globin gene. Synthetic 3' splice site sequence oligonucleotides were inserted into the EcoRl restriction site, forty nine nucleotides downstream of the authentic rabbit beta-globin IVS-2 3' splice site. The oligonucleotides conformed to the established 3' splice site consensus sequence and allowed for variations within this sequence. The authentic site served as a constant reference site against which the strengths of the synthetic sites could be measured. When spliced in HeLa cells in vivo, all constructs tested were seen to choose the authentic 3' splice site over the synthetic 3' splice site under test. A series of mutageneses was carried out to try to decrease the intrinsic strength of the authentic site and/or improve the environment of the synthetic site such that the overall strengths of the two sites might be balanced. An AG→CG mutation at the authentic 3' splice site caused the synthetic 3' splice site to be activated as a cryptic site in vivo and in vitro. In this case lariat formation was mapped to an artificially created branch point within exon 3. Splicing component binding to both 3' splice sites was investigated by looking at protection of the RNA from oligonucleotide directed cleavage by RNase H. Initial protection of both 3' splice sites was independent of the final choice of site. However, branch point protection was dependent on the 3' splice site chosen. Components bound to the authentic 3' splice site could be immunoprecipitated whether that site was chosen or not. The synthetic 3' splice site was poorly precipitated even when it was chosen. This data tends to suggest that the synthetic 3' splice site directs inefficient complex assembly, and that at least partial complex assembly occurs at a 3' splice site which has been inactivated by an AG→CG mutation. Preliminary work was carried out to develop a method for the analysis of splicing component binding to either or both 3' splice sites of material within fully and partially assembled splicing complexes (spliceosomes) isolated by sucrose gradient sedimentation.
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Arque, Armengol Anna. "Comparison between preinvestigations and detailed geotechnical site characterization of City Link, Stockholm." Thesis, KTH, Mark- och vattenteknik (flyttat 20130630), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-171800.
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A statistical comparison between the pre-investigations and the detailed site characterization while tunneling was performed in three areas of different rock quality in the Södermalm’s Tunnel. An overview of the site investigations performed prior to the construction works and the consequences in the tunneling method are also presented in this study. The statistical analyses in this study showed low correlation within the results obtained from the geotechnical investigations performed prior and while tunneling. The correlation diminishes as the rock mass quality decreases; however, in areas where the rock mass quality is high, the correlation is not as elevated as expected. The low association within those results may be due to diverse factors: the concentration of the pre-investigations in mostly three areas along the trace of the tunnel, and the extension of those results to the rest of the tunnel; the inappropriate utilization of the investigation techniques; and the lack of geotechnical data in the regional areas of Stockholm. The inaccurate geological characterization given by the pre-investigations leaded to great challenges in the most fractured and altered areas of the tunnel. A collapse occurred where the glaciofluvial sediments were in contact with the rock. The excavation had to be stopped and additional rock reinforcement had to be applied. Therefore, an increase of the expenses in terms of time and budget were the major consequences of the inaccurate predictions.
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Riding, Nathan. "The effect of ethnicity and body size on the athlete's heart and their impact on cardiovascular pre-participation screening." Thesis, Liverpool John Moores University, 2014. http://researchonline.ljmu.ac.uk/4586/.
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In response to the augmented haemodynamic load placed upon the heart by intense and prolonged exercise, various forms of physiological remodelling are elicited. The resultant cardiac structural, functional and electrical adaptations are coined the athlete’s heart. Due to the nature of the remodelling, in some cases these adaptations may however overlap with the diagnostic criteria for varying pathological conditions, often related to sudden cardiac death. Several variables are associated with the athlete’s heart including age, sex, sport, body size, and ethnicity. Ethnicity is of particular importance as athletes of an African/Afro-Caribbean ethnicity demonstrate a greater prevalence of abnormal changes suggestive of pathology. There is however paucity in the literature of the athlete’s heart among other ethnicities. For this reason Study 1 investigated the impact of Arabic ethnicity upon the structure, function and electrophysiology of the heart in male athletes. Study 1 identified that while Arabic athletes had larger hearts than Arabic controls, they had significantly smaller hearts than their Black and Caucasian athletic counterparts. While Black athletes had a significantly greater prevalence of training unrelated/abnormal ECG findings, Arabic and Caucasian both had similar levels of training unrelated/abnormal findings, suggesting the European Society of Cardiology guidelines for ECG interpretation in athletes are applicable for the ethnicity. Study 2 investigated another important facet of the athlete’s heart, which is body size. Study 2 identified that while there was a progressive relationship between body size and cardiac dimensions, the previously identified upper limits of cardiac structural remodelling were applicable even among those with a body surface area (BSA) over 2.3m2. Among the cohort of athletes with a BSA >2.3m2, Black athletes demonstrated significantly greater wall thickness’ than Caucasian and Arabic athletes. The second aspect to the thesis highlighted how the findings of Study 1 and 2 impact upon pre-participation screening. While debate still exists around the most effective methodology to screen for pathological cardiac conditions, several organisations mandate the use of the echocardiography alongside the resting 12-Lead ECG. Study 3 established that should echocardiography be limited to use as a follow up investigation, significant cost benefits could be elicited (47% reduction). The premise of this significant cost reduction was that no pathological case was identified by echocardiography in isolation. While still found to be useful in confirming pathology, significantly, in our study the investigation failed to identify two cases of hypertrophic cardiomyopathy. Study 4 investigated the implications of adopting modified ECG interpretation guidelines in light of the criticism that ECG screening should be avoided due to a high false positive rate. Utilising an ethnically diverse cohort, Study 4 demonstrated that using the ‘Refined’ criteria reduced the false positive rate from 22% when using the 2010 ESC guidelines to 5%. Importantly both criteria achieved 100% sensitivity, highlighting the importance of the ECG in cardiovascular screening.
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Kimball, Vaughn R. "Variability in late prehistoric prey-use strategies of the southeastern Columbia Plateau a test using the Harder Site faunal assemblage /." Online access for everyone, 2005. http://www.dissertations.wsu.edu/Thesis/Spring2005/v%5Fkimball%5F050505.pdf.
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Yao, Yuan. "Towards Comprehensive Side-channel Resistant Embedded Systems." Diss., Virginia Tech, 2021. http://hdl.handle.net/10919/104662.
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Embedded devices almost involve every part of our lives, such as health condition monitoring, communicating with other people, traveling, financial transactions, etc. Within the embedded devices, our private information is utilized, collected and stored. Cryptography is the security mechanism within the embedded devices for protecting this secret information. However, cryptography algorithms can still be analyzed and attacked by malicious adversaries to steal secret data. There are different categories of attacks towards embedded devices, and the side-channel attack is one of the powerful attacks.
Unlike analyzing the vulnerabilities within the cryptography algorithm itself in traditional attacks, the side-channel attack observes the physical effect signals while the cryptography algorithm runs on the device. These physical effects include the power consumption of the devices, timing, electromagnetic radiations, etc., and we call these physical effects that carry secret information side-channel leakage. By statistically analyzing these side-channel leakages, an attacker can reconstruct the secret information.
The manifestation of side-channel leakage happens at the hardware level. Therefore, the designer has to ensure that the hardware design of the embedded system is secure against side-channel attacks. However, it is very arduous work. An embedded systems design including a large number of electronic components makes it very difficult to comprehensively capture every side-channel vulnerability, locate the root cause of the side-channel leakage, and efficiently fix the vulnerabilities. In this dissertation, we developed methodologies that can help designers detect and fix side-channel vulnerabilities within the embedded system design at low cost and early design stage.Doctor of Philosophy
Side-channel leakage, which reveals the secret information from the physical effects of computing secret variables, has become a serious vulnerability in secure hardware and software implementations. In side-channel attacks, adversaries passively exploit variations such as power consumption, timing, and electromagnetic emission during the computation with secret variables to retrieve sensitive information. The side-channel attack poses a practical threat to embedded devices, an embedded device's cryptosystem without adequate protection against side-channel leakage can be easily broken by the side-channel attack. In this dissertation, we investigate methodologies to build up comprehensive side-channel resistant embedded systems. However, this is challenging because of the complexity of the embedded system. First, an embedded system integrates a large number of components. Even if the designer can make sure that each component is protected within the system, the integration of the components will possibly introduce new vulnerabilities. Second, the existing side-channel leakage evaluation of embedded system design happens post-silicon and utilizes the measurement on the prototype of the taped-out chip. This is too late for mitigating the vulnerability in the design. Third, due to the complexity of the embedded system, even though the side-channel leakage is detected, it is very hard to precisely locate the root cause within the design. Existing side-channel attack countermeasures are very costly in terms of design overhead. Without a method that can precisely identify the side-channel leakage source within the design, huge overhead will be introduced by blindly add the side-channel countermeasure to the whole design. To make the challenge even harder, the Power Distribution Network (PDN) where the hardware design locates is also vulnerable to side-channel attacks. It has been continuously demonstrated by researchers that attackers can place malicious circuits on a shared PDN with victim design and open the opportunities for the attackers to inject faults or monitoring power changes of the victim circuit. In this dissertation, we address the challenges mentioned above in designing a side-channel-resistant embedded system. We categorize our contributions into three major aspects—first, we investigating the effects of integration of security components and developing corresponding countermeasures. We analyze the vulnerability in a widely used countermeasure - masking, and identify that the random number transfer procedure is a weak link in the integration which can be bypassed by the attacker. We further propose a lightweight protection scheme to protect function calls from instruction skip fault attacks. Second, we developed a novel analysis methodology for pre-silicon side-channel leakage evaluation and root cause analysis. The methodology we developed enables the designer to detect the side-channel leakage at the early pre-silicon design stage, locate the leakage source in the design precisely to the individual gate and apply highly targeted countermeasure with low overhead. Third, we developed a multipurpose on-chip side-channel and fault monitoring extension - Programmable Ring Oscillator (PRO), to further guarantee the security of PDN. PRO can provide on-chip side-channel resistance, power monitoring, and fault detection capabilities to the secure design. We show that PRO as application-independent integrated primitives can provide side-channel and fault countermeasure to the design at a low cost.
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Kwon, Jonghan. "Characterization of deformation mechanisms in pre-strained NiAl-Mo composites and α-Ti alloy." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1343796987.
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Kalayci, Ahmet Serhat. "Development of Surface Flaw Thresholds for Pre-Cured Fiber Reinforced Polymer and Groove Size Tolerance for Near Surface Mounted Fiber Reinforced Polymer Retrofit Systems." FIU Digital Commons, 2008. http://digitalcommons.fiu.edu/etd/21.
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Since the introduction of fiber reinforced polymers (FRP) for the repair and retrofit of concrete structures in the 1980’s, considerable research has been devoted to the feasibility of their application and predictive modeling of their performance. However, the effects of flaws present in the constitutive components and the practices in substrate preparation and treatment have not yet been thoroughly studied. This research aims at investigating the effect of surface preparation and treatment for the pre-cured FRP systems and the groove size tolerance for near surface mounted (NSM) FRP systems; and to set thresholds for guaranteed system performance. The research included both analytical and experimental components. The experimental program for the pre-cured FRP systems consisted of a total of twenty-four (24) reinforced concrete (RC) T-beams with various surface preparation parameters and surface flaws, including roughness, flatness, voids and cracks (cuts). For the NSM FRP systems, a total of twelve (12) additional RC T-beams were tested with different grooves sizes for FRP bars and strips. The analytical program included developing an elaborate nonlinear finite element model using the general purpose software ANSYS. The model was subsequently used to extend the experimental range of parameters for surface flatness in pre-cured FRP systems, and for groove size study in the NSM FRP systems. Test results, confirmed by further analyses, indicated that contrary to the general belief in the industry, the impact of surface roughness on the global performance of pre-cured FRP systems was negligible. The study also verified that threshold limits set for wet lay-up FRP systems can be extended to pre-cured systems. The study showed that larger surface voids and cracks (cuts) can adversely impact both the strength and ductility of pre-cured FRP systems. On the other hand, frequency (or spacing) of surface cracks (cuts) may only affect system ductility rather than its strength. Finally, within the range studied, groove size tolerance of +1/8 in. does not appear to have an adverse effect on the performance of NSM FRP systems.
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Stands, Leah Rae. "Regulation of U1 snRNP / 5' splice site interactions during pre-MRNA splicing in Saccharomyces cerevisiae." Connect to this title online, 2003. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1056395043.
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Thesis (Ph. D.)--Ohio State University, 2003.Title from first page of PDF file. Document formatted into pages; contains xiv, 236 p.; also includes graphics (some col.) Includes bibliographical references (p. 215-236). Available online via OhioLINK's ETD Center
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Selimi, Arta, and Simone Stodell. "Pre-internationalization : - A case study of the decision to internationalize among small and medium sized Swedish enterprises." Thesis, Linnéuniversitetet, Ekonomihögskolan, ELNU, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-20655.
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The process of internationalization has been one of the major areas of interest for researchers for over four decades. The phase that precedes internationalization for firms, known as the pre-internationalization phase, has also been of interest to study. Firms that are in this early stage of becoming international, are characterized by being active only in the domestic market but with intentions to expand. However, within this phase, little is known about the stimuli that affect firms to expand their operations to foreign markets. By combining the traditional theories of the drivers and barriers to internationalize, with the new theories concerning the entrepreneurial influence in small and young firms, this study serves to complement a particular research gap in the pre-internationalization phase. The purpose of this study is to describe the pre-internationalization phase of SMEs, analyze how drivers, barriers and entrepreneurial characteristics of managers affect the decision to internationalize and to contribute to a further understanding of the research gap in the preinternationalization phase. A deductive research approach and a qualitative research method have been chosen for this study. In this way, in-depth answers can provide understanding to a phenomenon that is still partly undiscovered. To increase understanding in a broader environment than within one organization the multiple case study design is used for this study. Therefore, three managers from different firms participated in interviews, which is the basis for the empirical data. When the empirical data is combined with relevant theories it provides a basis for the analysis where the effects of drivers, barriers and international entrepreneurship are evaluated. This analysis provides a foundation for the conclusion that it is a necessity to combine traditional and new theories, with further empirical research, to fully understand why young domestic small and medium-sized enterprises decide to internationalize. When these are put together, it is possible to establish that barriers that are neglected by entrepreneurs are seemingly small impediments, in comparison to the drivers to reach success and the entrepreneurial urge to expand.
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Eriksson, Alexander, and Veronica Flykt. "Concrete floor : Design of prefabricated pre-stressed hollow core slabs with verification through PRE-Stress and comparison with site-cast slab." Thesis, KTH, Byggteknik och design, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-279158.
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The most common prefabricated concrete slabs are hollow core slabs, which are usually pre-tensioned. How to design these parts is not compiled today in a manual where it is clear how this is done, this knowledge is generally classified as expert knowledge. The purpose was to bring forth how to design prefabricated pre-stressed hollow core slabs, HD/F, and then create a design aid that is compared by hand calculations with the PRE-Stress design program from StruSoft. Furthermore, to compare it with site-cast concrete slabs to see differences in the amount of material and the thickness of the structure under the same conditions.The design aid is not complete as some limitations had to be made. When it comes to results, the hand calculations in comparison with PRE-Stress have not resulted in identical answers but have proven to be on the safe side consistently through the design, which indicates that the design aid is fully functional. In the comparison with site-cast concrete slabs, it can be noted that prestressed hollow core slabs require less concrete volume, slimmer construction, and longer span widths but greater reinforcement volume.Det vanligaste prefabricerade betongbjälklaget är håldäcksplattor som oftast är spännarmerade. Hur man dimensionerar dessa bärverksdelar finns idag inte samlat i en handbok där det står tydligt hur man gör, den kunskapen klassas generellt som expertiskunskap. Syftet var att ta fram hur man dimensionerar prefabricerade förspända håldäcksplattor, HD/F, och sedan skapa ett dimensioneringshjälpmedel som jämförs genom handberäkningar med PRE-Stress dimensioneringsprogram från StruSoft. Vidare genomfördes jämförande beräkningar för platsgjutet betongbjälklag för att se skillnader i materialmängd och konstruktionstjocklek under samma förutsättningar.Dimensioneringshjälpmedlet är inte komplett då vissa avgränsningar behövts göras. När det kommer till resultat har handberäkningar i jämförelse med PRE-Stress inte resulterat i identiska svar, men visat sig hamna på säkra sidan konsekvent genom dimensioneringen vilket tyder på att dimensioneringshjälpmedlet är fullt användbart. I jämförelsen med platsgjutet bjälklag kan man konstatera att förspända håldäcksplattor ger mindre betongvolym, slankare konstruktion och längre spännvidder men större armeringsmängd.
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Abbott, Kirby Carleton University Dissertation Sociology. "South Side Cape Breton miners; a sociological summary of pre 1879 to 1951 transformations." Ottawa, 1985.
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Jørstad, Steinar. "Reduction of Pelletized Tyssedal Ilmenite and the Effect of Changing Gas Composition and Flow, Pellet Size and Pre Oxidation Condition." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for materialteknologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-16338.
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This master thesis is based on reduction experiments of pelletized Tyssedal ilmenite. The focus is set on the effect of changing parameters such as gas composition, gas flow, pellet size and pre-oxidation condition. The results are interpret regarding values of conversion, degree of metalization, XRF-analysis and microstructure images. Based on these results the aim was to find out how these parameters influenced reduction. Another goal was to reveal what hampered reduction inside both grains and pellets and caused the two stage reduction behaviour. EPMA was used to examine pellets and grains and to look for explanation for the slow reduction. XRD-analysis was decisive for explaining the importance of optimum pre-oxidation for the subsequent reduction. Pre-oxidized and green pellets with a size fraction of 8-10 mm were heated in a thermogravimetric analyzer. Ar was used during heating and cooling. Reduction occurred at 930-940 °C, with either CO, H2 or both for up to 45 minutes. Gas flows used were 4.8, 7 and 9 Nl/min. In total 18 experiments were carried out. Weight before and after reduction was measured, calculations of degree of metalization, XRF- and XRD-analysis was done. Microstructure images, point analysis, line scan and mapping were obtained by EPMA. Highest final values of conversion, c. 0.9, were obtained for pre-oxidized pellets from 2011 reduced with H2. Maximum degree of metalization, 94-99 % were obtained after reduction of pre-oxidized pellets from 2010. Final value of conversion and degree of metalization were 0.23 and c. 24 % higher for pre-oxidized pellets from 2010 than from 2011. Only green pellets from 2011 was harder to reduce with CO. Reducibility was not increased with the pre-oxidation conditions at ETI Tyssedal in January 2011. In spite of that the pre-oxidized pellets from 2010 and 2011 are made in the same manner and from the same raw material they react differently during reduction. This should be kept in mind when comparing results from different sources. Reduction of pre-oxidized pellets occurred in two distinct linear stages separated by a clear bend. A normal behaviour with steadily decreasing oxygen removal rate was observed with green pellets. An increased flow of CO from 7 Nl/min to 9 Nl/min resulted in decreased reduction. Examination by EPMA confirmed the presence of the barrier effect and higher amount of oxygen 0.6-1.0 mm from the surface. This indicates hampered reduction in grains and pellets. This combined with slow migration of CO/CO2 in the pellets can partly explain the unusual reduction behaviour. Pre-oxidized pellets from 2010 contains higher amount of the easily reducible M3O5, and less M2O3 compared to pre-oxidized pellets from 2011. The less reducible M3O4 was also found in the pre-oxidized pellets from 2011, making them harder to reduce.
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Mobli, Mostafa. "Quantitative effects of bulb size, pre- and post-planting environment on flowering and seed production in onions, Allium cepa L." Thesis, University of Reading, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358058.
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Pereira, Grégory. "Potrero de Guadalupe : anthropologie funéraire d'une communauté pré-tarasque du nord du Michoacán, Mexique /." Oxford : Archaeopress, 1999. http://catalogue.bnf.fr/ark:/12148/cb371966501.
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