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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Investigation into the Paleobiology of Dasypus bellus Using Geometric Morphometrics and Variation of the Calcaneus

Jasinski, Steven E., Wallace, Steven C. 01 January 2014 (has links)
The extinct taxon Dasypus bellus has long been considered identical to the extant Dasypus novemcinctus osteologically when disregarding allometric differences. In this study, we undertake a preliminary investigation into this extinct taxon and an extant relative D. novemcinctus, by comparing the calcanea of these two dasypodids. Clear osteological differences are observed including a mediolaterally-reduced facet region, an anteriorly-shortened calcaneal head, a reduced peroneal process, and a curved and dorsoventrally-shortened calcaneal foot in D. bellus. Such characters are not allometric and likely correlate to distinct behavioral differences. Specifically, we suggest that D. novemcinctus maintains a more fossorial lifestyle, while the larger D. bellus was likely more terrestrial, with potentially little digging behavior. Such lifestyle differences could not only explain the osteological differences present, but also why fossils of D. bellus have been recovered farther north than the present range of D. novemcinctus. Fossils of Dasypus may need to be re-evaluated to determine how these two taxa relate temporally and geographically, which may have further implications regarding some past interpretations and provide new details on the behavior and potential relationships between these (and other) xenarthrans.
42

A New Species of Ceratogaulus From Nebraska and the Evolution of Nasal Horns in Mylagaulidae (Mammalia, Rodentia, Aplodontioidea)

Calede, Jonathan J.M., Samuels, Joshua X. 01 September 2020 (has links)
Members of the Mylagaulidae have been known for over a century to bear nasal horns; the only rodents, extinct or extant, ever to have done so. This striking feature is known from five of the over 30 species of mylagaulid rodents discovered across North America and Eurasia, all relatively large animals that were likely less fossorial than their relatives. We describe herein a sixth new species of horned mylagaulid. This new taxon from Sioux County, Nebraska, offers the opportunity to reassess the phylogenetic relationships of Mylagaulidae and test several evolutionary hypotheses. Our analyses demonstrate that horns evolved only once in Mylagaulidae, in the common ancestor of Ceratogaulus, first as short horns exapted from the thickened nasals of fossorial ancestors, and later as taller horns. The horns evolved following a positive allometric scaling with body mass that suggests a response to predation pressure in these nearly blind animals. The evolution of tall horns also corresponds to a jump in body mass. The largest mylagaulids are not horn-bearing species, however. Additional analyses of the complex pattern of body mass evolution we reveal will be necessary to explain the evolution of the largest head-lift digging rodents in Earth history. https://zoobank.org/urn:lsid:zoobank.org:pub:81FE999A-F79E-4BD4-9A81-2C7D3D5D81CD.
43

Pharmacokinetic Evaluation and Modeling of Tyrosine Kinase Inhibitors Nilotinib and Imatinib in Preclinical Species to Aid their Repurposing As Anti-Viral Agents

Ananthula, Hari Krishna 05 December 2017 (has links)
No description available.
44

Prioritizing Management of <i>Ailanthus altissima</i>at the Edge of Appalachia Preserve

Polgar, Sarah K. 25 April 2008 (has links)
No description available.
45

Predicting food consumption and production in fish populations : allometric scaling and size-structured models

Wiff, Rodrigo January 2010 (has links)
Life-history traits in fish populations are highly correlated. A subset of these correlations are called allometric scaling, they refer to biological processes which can be described using body size as independent variable. Particularly, allometric scaling related with food consumption (Q) and biomass production (P) has gained the attention of ecologists for several decades. This thesis proposes a quantitative framework for food consumption, which allows both the identification of the mechanisms underlying the allometric scaling for Q and the development of a predictive model for consumption to biomass ratio (Q/B) in fish populations. This thesis is based on the fact that food consumption can be inferred from first principles underlying the von Bertalanffy growth model. In addition, it has been noticed in the literature that biomass production and food consumption show similar allometric scaling dependence, therefore, both can be derived from these first principles. Thus, a similar quantitative framework was used to produce models for P/B in fish populations. Once functional forms for production and food consumption were identified, a third model was developed for the ratio between production and consumption (P/Q). This ratio is usually named ecological efficiency because it determines how efficiently a population can transform ingested food into biomass. Several authors have noticed that P/Q remains invariant (independent of body size) across species. From a theoretical point of view, the results presented here allow the first quantitative explanation for the existence of the allometric scaling for Q/B and the invariance of P/Q across fish species. These results, together with the explanation for allometry in P/B reported in the literature, suggest that the regular across-species pattern for the trio {P/B,Q/B,P/Q} can be explained by basic principles that underpin life-history in fish populations. This quantitative framework for the trio {P/B,Q/B,P/Q} is based on an explicit dependence with body size, which simplifies the estimation of these quantities. Model complexity depends, in part, on which data are available. Models were applied to real data from commercially important species fished in Chile. Statistical properties of the new models were evaluated by an intensive resampling approach. The simplest possible model for the trio {P/B,Q/B,P/Q} rests on the assumption of a stable age distribution. These quantities have a key importance in ecosystem modelling because they determine population energetics in terms of food intake by predation and the transformation of this energy into population biomass of predators. Application of the new models produces results which were comparable to those given by standard methods. This thesis is a result of multidisciplinary research which attempts to make a contribution to the understanding of the mechanisms underlying the allometric scaling of food consumption and production in fish populations. It proposes models for the trio {P/B,Q/B,P/Q} and thus, has the potential to be widely applicable in fisheries science.
46

Growth laws for sub-delta crevasses in the Mississippi River Delta: observations and modeling

Yocum, Tara A. 19 May 2017 (has links)
In this study we assessed growth laws of sub-delta crevasses in the Mississippi River delta plain, experimental laboratory deltas, and compared them to previously studied river dominated large deltas worldwide. Metrics for channel and delta geometry for each system were obtained using a combination of geospatial tools, bathymetric datasets, sediment size, and hydrodynamic observations. Most crevasses and experimental deltas appear to obey delta growth laws suggesting that they exhibit planform metrics similar to larger deltas. However, some channels within each system, exhibit outlier behavior (e.g. asymmetric growth) where channel length is much larger than channel width. Hydrodynamic observations and morphodynamic modeling results, support the role of confinement in governing this response, through direct lateral confinement of the receiving basin width and depth thus guiding channels, and indirect confinement caused by sediment cohesion, whereby natural levees guide the systems asymmetric channel growth.
47

Allometric Scaling of Brain, Brain Components and Neurons with Body Size of Social Bees

Gowda, Vishwas, Gowda, Vishwas January 2016 (has links)
Animals in general vary immensely in body size, which greatly affects their morphology, physiology, survival, and nutritional requirements. The nervous system is also affected by variation in body size, which, in turn, shapes the perception of environmental stimuli and the behavior of animals. Comparative studies of vertebrates suggest that larger brains and their integrative centers comprise more and generally larger neurons (Jerison, 1973; Kaas, 2000), but much less is known about brain - body size relations in invertebrates. Closely related social bee species are well suited to study correlations between body size and brain composition. Different honey bee species vary in body size yet differ little in their ecological requirements and behavior and bumble bees feature a large range of body sizes even within a single colony.
48

Light intensity influences on algal pigments, proteins and carbohydrates: implications for pigment-based chemotaxonomy

Unknown Date (has links)
Phytoplankton Chlorophyll a (CHLa), total protein, colloidal carbohydrates, storage carbohydrates and taxonomic pigment relationships were studied in two cyanophytes (Microcystis aeruginosa and Synnechococcus elongatus), two chlorophytes (Dunaliella tertiolecta and Scenedesmus quadricauda), one cryptophyte (Rhodomonas salina), two diatoms (Cyclotella meneghiniana and Thalassiosira weissflogii) and one dinophyte (Amphidinium carterae) to assess if algal biomass could be expressed in other indices than just chlorophyll a alone. Protein and carbohydrates are more useful currencies for expressing algal biomass, with respect to energy flow amongst trophic levels. These phytoplankton were grown at low light (LL = 37 (So(Bmol photons m-2 s-1), medium light (ML = 70-75 (So(Bmol photons m-2 s-1), and high light (HL= 200 (So(Bmol photons m-2 s-1). / Even though pigment per cell increased with increasing light intensity, statistically light had very little effect on the CHL a : taxonomic marker pigment ratios, as they covaried in the same way. Protein, colloidal carbohydrates and storage carbohydrates per cell all increased with increasing light intensity, but they did not covary with CHLa. Statistical data showed that light intensity had a more noticeable effect on protein: CHL a, colloidal carbohydrate: CHLa, storage CHO: CHLa, therefore a general mathematical expression for these relationships cannot be generated. This study showed that light intensity does have an influence on these biomass indices, therefore, seasonal and latitudinal formulas may be required for meaningful algal biomass estimation. However, more studies are needed if that goal is to be realized. / While studying the effects of light intensity on algal pigment content and concentration, a new pigment was isolated from a cyanophyte (Scytonema hofmanii) growing between 300-1800 (So(Bmol photons¨m-2¨s-1 and from samples collected in areas of the Florida Everglades. This pigment was characterized and structurally determined to possess indolic and phenolic subunits that are characteristic of scytonemin and its derivatives. In addition, the pigment has a ketamine functionality which gives it its unique polarity and spectral properties. Based on the ultra violet/visible absorbance data, this pigment was postulated to be protecting the chlorophyll a and cytochrome Soret bands as well as a and (Sb (Bbands of the cytochromes (e.g. cytc-562) in the photosynthetic unit. / by Cidya Grant. / Thesis (Ph.D.)--Florida Atlantic University, 2011. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2011. Mode of access: World Wide Web.
49

Modelos alométricos para a estimativa da fitomassa de Mata Atlântica na Serra do Mar, SP\". / Allometric models for estimating the phytomass of the Atlantic Forest of the Serra do Mar, SP.

Burger, Déborah Moreira 04 May 2005 (has links)
O objetivo deste estudo foi desenvolver e validar modelos preditores para a fitomassa epigéa da mata atlântica, formação vegetal que cobre a Serra do Mar no estado de São Paulo. Em duas parcelas de 100m2, 82 árvores foram cortadas, ao nível do solo, e anotadas suas medidas de altura e diâmetro. As folhas foram separadas dos ramos para determinação do peso fresco da porção foliar e lenhosa. Amostras de cada fração foram secas em estufa a 80o C, até peso constante, para determinação do peso seco. As árvores foram distribuídas em duas amostras aleatórias, sendo uma utilizada para o desenvolvimento das equações de regressão, e a outra para validá-las. Os modelos foram desenvolvidos através da análise de regressão linear simples e múltipla, tendo como variável dependente o peso seco (PS) e, como variáveis independentes a altura (h), o diâmetro (d) e o (d2h). A análise de validação foi feita através do coeficiente de correlação de Pearson, teste t-Sudent pareado e através do erro padrão da estimativa. As melhores equações para estimar o peso seco das árvores foram: lnPS = -4,1519 + 1,06068 ln d2h (r2=0,82; sy/x= 0,42; ricc=0,92); lnPS = -6,7171 + 1,30308 ln d2h (r2=0,88; sy/x= 0,44; ricc=0,93) e lnPS = -6,80067 + 3,77738 ln d (r2=0,92; sy/x =0,37; ricc=0,87). / The purpose of this study was develop and validate equations to estimative the aboveground phytomass of the Atlantic Forest, at the Serra do Mar, São Paulo, Southeast Brazil. In two available plots of 100m2, 82 trees were cut down at ground level. From each tree height and diameter was determined. Leaves and woody material were separated in order to determine their fresh weights in field conditions. Samples of each fraction were oven dried at 80o C to constant weight to determine their dry weight. The trees data were divided into two random samples. One sample was used for the development of the regression equations, and the validation was done using other one. The models were developed using single and multiple linear regression analysis, where the dependent variable was the dry mass and the independent variables were height (h), diameter (d) and d2h. The validation was done using Pearson correlation coefficient, paired t-Student test and standard error of estimation. The best equations to estimate aboveground phytomass were: lnPS = -4,1519 + 1,06068 ln d2 h (r2=0,82; sy/x= 0,42; ricc=0,92); lnPS = -6,7171 + 1,30308 ln d2h (r2=0,88; sy/x= 0,44; ricc=0,93) and lnPS = -6,80067 + 3,77738 ln d (r2=0,92; sy/x =0,37; ricc=0,87).
50

Determinação da potência aeróbia de crianças e adolescentes a partir de ajustes alométricos / Determination of the aerobic power in children and adolescents by scaling

Borges, Gustavo André 24 April 2009 (has links)
O objetivo do estudo foi determinar e analisar o comportamento da potência aeróbia (VO2pico) em valores absolutos e relativos por meio de expoentes lineares e alométricos, em crianças e adolescentes de 10 a 16 anos de Marechal Candido Rondon Paraná. A amostra foi intencionalmente composta por 248 indivíduos, sendo 124 rapazes e 124 moças. Medidas de estatura, massa corporal (MC) e dobras cutâneas foram realizadas. A gordura corporal e a massa corporal magra (MCM) foram determinadas pela equação de Boileau et al. (1986) para ambos os sexos. A potência aeróbia foi determinada diretamente por meio de teste cardiopulmonar de esforço em esteira, segundo o protocolo modificado de Balke, para ambos os sexos. Medidas ventilatórias (VE, VO2, QR) e homodinâmicas (FC) foram obtidas através do analisador metabólico de gazes VO2000 e do transmissor Polar, a cada 10 segundos. No tratamento estatístico dos dados, foi utilizada a estatística descritiva e as diferenças entre os sexos foram verificadas pelo teste t para amostras independentes. Os expoentes alométricos foram determinados através de uma regressão log-linear. Os resultados demonstraram que dos 10 aos 16 anos, os ganhos na potência aeróbia absoluta foram de 107% para os rapazes (1,67 para 3,46 L·min-1) e 66% para as moças (1,57 para 2,61 L·min-1), com diferenças a partir dos 14 anos. Os ganhos da potência aeróbia relativa à massa corporal foram de 12% (48,8 para 54,5 mL·kg-1·min-1) e 1% (42,9 para 43,3 mL·kg-1·min-1), com diferenças significantes entre os sexos em todas as idades, enquanto que relativos à MCM foram de 8% (58,0 para 62,9 mL·MCM-1·min-1) e 6% (53,3 para 56,3 mL·MCM- 1·min-1) para rapazes e moças respectivamente, com diferenças significantes entre os sexos a partir dos 12 anos. Os expoentes nos diferentes grupos etários e sexos variaram de 0,30-0,94 para a MC e de 0,44-1,32 para a MCM. No ajuste alométrico da MC, o expoente 0,91 (r=0,88) foi obtido para todos os rapazes, 0,82 (r=0,85) para todas as moças e 0,85 (r=0,81) para ambos os sexos. O ajuste da MCM gerou o expoente 1,00 (r=0,94) para os rapazes, 1,01 (r=0,87) para as moças e 1,02 (r=0,89) para ambos os sexos. Concluiu-se que a potência aeróbia de crianças e adolescentes foi adequadamente ajustada pela MCM1,0 e alométricamente pela MC0,85 / The aim of this study was to determine and analyze the absolute e and relative aerobic power (VO2peak) by mean of linear and allometric exponents in children and adolescents, ages 10 to 16 years from Marechal Cândido Rondon Paraná. Body mass (BM), height end skinfold thickness were measure in an intentional sample of 248 schoolchildren (124 boys and 124 girls). Body fat and lean body mass (LBM) were estimated by the equation suggested by Boileau et al. (1982) in both sexes. Aerobic power was determinate directly using a treadmill by mean of a modified Balke protocol and a VO2000 portable metabolic system and heart rate by Polar transmission, each ten seconds. Descriptive statistics were use for all data. The difference between sexes was determined by t test, and the allometric exponents by log-linear regression. The gain in VO2peak absolute was 107% in boys (1,67 to 3,46 L·min-1) and 66% in girls (1,57 to 2,61 L·min-1) from 10 to 16 years old. Absolute VO2peak was similar for boys and girls in ages 10, 11, 12 and 13 years old. The gain was 12% (48,8 to 54,5 mL·kg-1·min-1) and 1% (42,9 to 43,3 mL·kg-1·min-1) to VO2peak relative to BM and 8% (58,0 to 62,9 mL·MCM-1·min-1) and 6% (53,3 to 56,3 mL·MCM-1·min-1) relative to LBM, for boys and girls respectively. The differences in VO2peak relative to BM were significant in all ages, with boys showing higher values. Boys also showed significantly higher values in VO2peak relative to LBM from ages 12 to 16 years. Allometry applied to VO2peak relative to BM determinate an exponent of 0.91 for boys, 0.82 for girls and 0.85 for both sexes. Allometry applied to VO2peak relative to LBM revealed an exponent of 1.00 for boys, 1.01 for girls and 1.02 for the both sexes. The data suggest that VO2peak were better adjust linearly by LBM and by MC0,85

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