A idade e crescimento da lula Doryteuthis plei da região do litoral norte do Estado de São Paulo é descrita com base em 424 exemplares entre 1,58 a 267 mm de comprimento de manto (ML). Os estatólitos foram utilizados como ferramenta de análise de idade, bem como foi realizado um estudo ontogenético de sua morfometria e morfologia. Com o objetivo de analisar e aprimorar a curva e a taxa de crescimento de D. plei, o presente estudo deu ênfase aos indivíduos em estágios iniciais do ciclo de vida. O formato dos estatólitos foi descrito e demonstrou semelhança à de outros loliginídeos, porém com características particulares, suficientes para a identificação da espécie. Houve relação entre ML e o comprimento dos estatólitos (SL), obtido pelo modelo de ajuste logarítmico. A idade dos exemplares amostrados foi estimada e com isto foi possível obter a curva de crescimento (relação idade e ML) da população em estudo, a qual foi ajustada pelo modelo logístico. O mesmo modelo de ajuste houve para os machos, porém para as fêmeas e para os juvenis, o melhor modelo foi o Gompertz. A longevidade da espécie no local de estudo foi estimada em aproximadamente oito meses. A taxa de crescimento e suas variações conforme as estações do ano foram estimadas. Foram evidenciados valores sendo em mm/dia quando em estádio imaturos em relação aos adultos e decrécimo acelerado após atingir 60 mm ML. Foram observadas diferenças da taxa de crescimento entre os sexos quando os exemplares atingem 150 mm de ML. Espécimes nascidos no inverno apresentaram maiores taxas de crescimento em relação aos nascidos em outras estações do ano. Através do retro-cálculo da idade, foi observado que durante todo o ano ocorrem nascimentos de D. plei, em maior frequência no primeiro semestre. É possível estimar a idade de D. plei tendo apenas as medidas de SL ou comprimento dos domos, sendo que para cada relação, o ajuste obtido foi o logarítmico. Os parâmetros de crescimento apresentados no presente estudo oferecem recursos para estudos de avaliação do estoque pesqueiro e biologia populacional. / Age and growth of the squid Doryteuthis plei from the northern shelf off São Paulo are described based on 424 specimens from 1.58 to 267 mm mantle length (ML). Statoliths were used as microstructures for aging, and an ontogenetic study of their morphological and morphometric was performed. The present study aimed to analyze and improve the growth curve and growth rate estimate of individuals of D. plei, emphasizing those in early stages of life cycle. The shape of statoliths was described and demonstrated similarity other loliginids, with particular characteristics sufficient to identify the species. There was a relationship between ML and statoliths length (SL) by the logarithmic model. The age of sampled specimens was estimated and it was possible to obtain the growth curve (relationship between age and ML) of the population in study, was better fitted by the logistic model. The same adjustment was found for males, but for females and juveniles, the Gompertz model was best suitable. The longevity of the species from place of study was estimated at approximately eight months. The growth rate and its variations were estimated according to the seasons, which evidenced higher values in mm/day in immature stage when compared to adults. In addition, individuals after reaching 60 mm ML accelerated a decrease in growth rate. Differences in growth rate between sexes were found after specimens reach 150 mm ML. Specimens born in winter had higher growth rates when compared to those born in other seasons. Through retro-calculation of age, it was observed that births of D. plei occur throughout the year, but most frequently in the first half. The study enables the age estimate of D. plei having only measures of SL or length of the statolith\'s domes. Growth parameters obtained provide information useful for stock assessment and population biology.

O estudo foi conduzido para estimar os parâmetros, avaliar e comparar os ajustes de curvas de crescimento corporal e dos componentes corporais físicos e químicos, de linhagens de frangos de corte sexados. Foram utilizados 1848 pintinhos de um dia de idade distribuídos em delineamento inteiramente casualizado com tratamentos em esquema fatorial hierárquico com os fatores: Sexo (Macho e Fêmea) e Linhagens (Cobb 500, Ross 308 e Hubbard Flex) dentro de cada sexo, totalizando seis tratamentos com seis repetições de 50 aves cada. A dieta experimental atendeu à necessidade nutricional para cada sexo. No primeiro dia foram abatidos oito animais de cada linhagem e sexo, obtendo o peso inicial dos componentes físicos e químicos e semanalmente as aves e rações de cada boxe foram pesadas para obter os dados de consumo de ração e peso corporal. De acordo com o peso médio de cada boxe foram feitos abates semanais, de dois a três animais (24h de jejum), sendo obtidos os pesos: corporal em jejum, corporal em jejum depenado, penas, carcaça, peito, coxa, sobrecoxa, asa, coração, fígado e moela. Outras duas aves (a partir do peso médio do boxe) em jejum foram foram selecionadas para o estudo de deposição dos nutrientes sobre o peso corporal em jejum depenado e de penas, tendo amostras destas características sido processadas, homogeneizadas e analisadas para matéria seca, nitrogênio, extrato etéreo e cinzas. Os parâmetros médios das curvas foram estimados, assim como os coeficientes alométricos e utilizados os critérios estatísticos de qualidade de ajuste (coeficiente de determinação, coeficiente de determinação ajustado, Critério de informação de Akaike e Critério de informação Bayesiano de Schwarz) para selecionar o modelo mais adequado. Também foi realizada a análise técnica (conversão alimentar) e econômica (margem bruta de comercialização -MB) a partir de estimativas de pesos corporais e de consumo de ração do melhor modelo selecionado, nos pesos e idade de abate predeterminados. A curva de Gompertz e a equação de alometria em função da proteína corporal foram selecionadas para estimar os valores individuais dos pesos de cada boxe e avaliar os efeitos de sexo e de linhagem em cada sexo. Os coeficientes alométricos foram heterogônicos negativos para a deposição de água corporal e órgãos; e heterogônicos positivos para cinzas, gordura corporal, carcaça e cortes da carcaça. Os machos tiveram maior desenvolvimento corporal e dos componentes com maior precocidade, exceto para gordura corporal. Macho Cobb 500 apresentou peso superior de peito; macho Hubbard maior deposição de proteína corporal, sendo mais eficiente tecnicamente e Ross 308, macho e fêmea, foram mais precoces para crescimento corporal e para a maior parte dos componentes. Na análise econômica utilizando o modelo Gompertz observou-se que machos apresentaram melhor conversão alimentar e MB do que fêmeas e Ross 308, apesar de ter comportamento superior em crescimento e precocidade, não foi tão eficiente tecnicamente e/ou economicamente quanto às linhagens Cobb 500 e Hubbard Flex nas últimas pesagens. / The study was conducted to estimate the parameters, evaluate and compare the adjustments of body growth curves and the physical and chemical body components, lines of sexed broilers. 1848 day-old chicks in a completely randomized design in a factorial design with treatments in hierarchical factorial design with the factors: sex (male and female) and strains (Cobb 500, Ross 308 and Hubbard Flex) within each sex, a total of six treatments with six replicates of 50 birds each. The experimental diet attended the nutritional requirement for each sex. On the first day, eight animals of each strain and sex were slaughtered, obtaining the initial weight of the physical and chemical components and weekly birds and every boxing feeds were weighed for the feed intake data and body weight. According to the mean weight of each pen were made weekly slaughter, two or three animals (24 h of fasting) were obtained, weights: Body fasting, body fasting plucking, feathers, carcass, chest, thigh, drumstick, wing, heart, liver and gizzard. Other two birds (from average body weight) fasted were used to study deposition of nutrients on body weight plucking fasting and feathers, and samples of these characteristics were processed, homogenized and analyzed for dry matter, nitrogen, extract ethereal and ashes. The average curve parameters were estimated, as well as the allometric coefficients and used statistical criteria for goodness of fit (coefficient of determination, adjusted determination coefficient, Akaike information criterion and Bayesian information criterion of Schwarz) to select the most appropriate model. It was also carried out technical analysis (feed conversion) and economic (gross margin trading -GM) from body weights estimates and feed intake of the best model selected, the weight and age of predetermined slaughter. The Gompertz curve and the allometry equation as a function of body protein were selected to estimate individual values of each pen weights and evaluate the effects of sex and strain of each sex. The allometric coefficients were negative heterogônic for the deposition of body water and organs; and positive heterogônic for ashes, body fat, carcass and carcass cuts. Males had earlier higher body development and their components, except for body fat. Male Cobb 500 showed a higher weight breast and thigh, male Hubbard had greater deposition of body protein being more efficient and technically Ross 308, male and female, were earlier for body growth and most of their components. In the economic analysis using the Gompertz model it was observed that males had better feed conversion and GM than females and Ross strain 308, despite having higher growth and precocity, it was not as efficient technically and / or economically as the Cobb 500 and Hubbard Flex. Males had higher body development and components begin earlier, except for body fat. Male Cobb 500 showed superior weight breast; Male Hubbard had greater deposition of body protein being more efficient and technically Ross 308, male and female, were earlier for body growth and most of the components. In the economic analysis using the Gompertz model was observed that males had better feed conversion and MB than females and Ross strain 308, that despite having superior behavior on growth and earliness, this last line was not as efficient technically and / or economically as the lines Cobb 500 and Hubbard Flex in the last weighing.

Biodiversity, ecosystems, industry and human health are threatened by invasive plant species. The costs of mitigating damages run into billions of pounds per annum. Fundamental to the control of invasive plant species is an ability to predict which species will become invasive. Yet identification of predictive differences between invasive and non-invasive species has proven difficult to pinpoint. In this thesis I identify several weaknesses within published literature, and using field experiments and meta-analyses we address these to find consistent predictors of invasiveness amongst plants. Specifically, I recognize that predictors of invasiveness can be identified by studying plant species in the native range because species may undergo phenotypic and demographic changes following naturalization (Chapters 2 – 5). I also recognize the importance of comparing globally invasive and non-invasive species, and the importance of accounting for phylogenetic relationships so as not to inflate or conceal differences (Chapters 2 – 4). Finally, I investigate whether particular analyses are more appropriate for investigating life history and demographic differences (Chapter 5). This thesis comprises an introductory chapter (Chapter 1), four data chapters (Chapters 2 - 5) and a general discussion (Chapter 6). Chapters 2 and 3 compare life history traits of plant species known to be invasive elsewhere, with their exported but non-invasive sympatric relatives in the native range. Chapter 4 utilizes Population Projection Matrices held within the COMPADRE Plant Matrix Database, to compare demographic projections of stable and transient dynamics of invasive and non-invasive plants; and Chapter 5 compares ten metrics, derived from Population Projection Matrices, of seven invasive species between the native and invaded range to determine if there are demographic or life history differences that facilitate invasion, and to identify those analyses that are most likely to reveal such differences. I find reproductive capacity to be a predictor of invasiveness, and that analyses of transient dynamics are more likely than analyses of projected stable dynamics to reveal demographic or life history differences between invasive and non-invasive species or populations of plants. I discuss these findings in the context of invasive risk assessment protocols and highlight future research opportunities.

Made available in DSpace on 2017-07-10T17:37:18Z (GMT). No. of bitstreams: 1 Silvio Douglas Ferreira.pdf: 1370632 bytes, checksum: 66a09d5927779ac975b32a3541a035ad (MD5) Previous issue date: 2016-02-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This study aimed to evaluate the biological cycle of susceptible biotypes of Digitaria insularis and resistant to glyphosate. The seeds of the biotypes of D. insularis were collected in populations from geographically distant agricultural areas belonging to producers Brejo Paraibano no history of using herbicides, so susceptible's supposed to, and west of Paraná, with a history of resistance. To carry out the evaluations of the growth curves of both experiments the same methodologies were used. The experimental design was a randomized block with four replications. The treatments consisted of plant collections seasons, carried out at regular intervals: 14; 21; 28; 35; 42; 49; 56; 63; 70; 77; 84; 91; 98; 105; 112 and 119 days after emergence (DAE), corresponding to periods of 16 samplings in each period. Biotypes were characterized as follows: AG biotype was considered susceptible, while the CVEL biotypes, ERO and GR were considered resistant and showed FR50 2,7; 3,4 and 7,7 respectively. Between the summer / fall (average temperature of 24,6 °C), the S biotype began issuing tillers and flowering an average of 14 and 21 DAE, respectively, before the resistant biotypes. However, in autumn / Winter (average temperature 19 °C) only biotype R1 was able to develop and finalize the biological cycle. In the summer / autumn period, the S biotype showed the highest absolute growth rate (TCA) at 84 DAE, being 82,3% higher than the resistant biotypes. The higher ratio of leaf area (RAF) was obtained by biotype R3 at 77 DAE, however, could not be verified differences in the relative growth rate (RGR) between biotypes. Biotypes evaluated showed differences during development especially among the phenological phases, so that the susceptible biotype was the earliest and with high reproductive potential / Objetivou-se avaliar o ciclo biológico de biótipos de Digitaria insularis suscetível e resistente ao glyphosate. As sementes dos biótipos de D. insularis, foram coletadas em populações provenientes de áreas agrícolas geograficamente distantes, pertencentes a produtores do Brejo Paraibano sem histórico de uso de herbicidas, logo, suspostamente suscetível, e da região oeste do Paraná, com histórico de resistência. Para realizar as avaliações das curvas de crescimento dos dois experimentos foram utilizadas as mesmas metodologias. O delineamento experimental foi em blocos casualizado com quatro repetições. Os tratamentos foram constituídos por épocas de coletas das plantas, realizadas em intervalos regulares de: 14; 21; 28; 35; 42; 49; 56; 63; 70; 77; 84; 91; 98; 105; 112 e 119 dias após a emergência (DAE), correspondendo a períodos de 16 coletas em cada período. Os biótipos foram caracterizados da seguinte maneira: biótipo AG foi considerado suscetível, enquanto que, os biótipos CVEL, ERO e GR foram considerados resistentes e apresentaram FR50 de 2,7; 3,4 e 7,7 respectivamente. No período o verão/outono (Temperatura média de 24,6°C), o biótipo S iniciou a emissão de perfilhos e o florescimento em média 14 e 21 DAE, respectivamente, antes que os biótipos resistentes. Entretanto, no período outono/inverno (Temperatura média de 19°C) apenas o biótipo R1 conseguiu se desenvolver e finalizar o ciclo biológico. No período verão/outono, o biótipo S apresentou maior Taxa de crescimento absoluto (TCA) aos 84 DAE, sendo 82,3% superior aos biótipos resistentes. A maior Razão da área foliar (RAF) foi obtida pelo biótipo R3 aos 77 DAE, porém, não foi possível verificar diferenças na Taxa de crescimento relativo (TCR) entre os biótipos. Os biótipos avaliados apresentaram diferenças durante o desenvolvimento principalmente entre as fases fenológicas, de modo que, o biótipo suscetível foi o mais precoce e com elevado potencial reprodutivo

O estudo foi conduzido para estimar os parâmetros, avaliar e comparar os ajustes de curvas de crescimento corporal e dos componentes corporais físicos e químicos, de linhagens de frangos de corte sexados. Foram utilizados 1848 pintinhos de um dia de idade distribuídos em delineamento inteiramente casualizado com tratamentos em esquema fatorial hierárquico com os fatores: Sexo (Macho e Fêmea) e Linhagens (Cobb 500, Ross 308 e Hubbard Flex) dentro de cada sexo, totalizando seis tratamentos com seis repetições de 50 aves cada. A dieta experimental atendeu à necessidade nutricional para cada sexo. No primeiro dia foram abatidos oito animais de cada linhagem e sexo, obtendo o peso inicial dos componentes físicos e químicos e semanalmente as aves e rações de cada boxe foram pesadas para obter os dados de consumo de ração e peso corporal. De acordo com o peso médio de cada boxe foram feitos abates semanais, de dois a três animais (24h de jejum), sendo obtidos os pesos: corporal em jejum, corporal em jejum depenado, penas, carcaça, peito, coxa, sobrecoxa, asa, coração, fígado e moela. Outras duas aves (a partir do peso médio do boxe) em jejum foram foram selecionadas para o estudo de deposição dos nutrientes sobre o peso corporal em jejum depenado e de penas, tendo amostras destas características sido processadas, homogeneizadas e analisadas para matéria seca, nitrogênio, extrato etéreo e cinzas. Os parâmetros médios das curvas foram estimados, assim como os coeficientes alométricos e utilizados os critérios estatísticos de qualidade de ajuste (coeficiente de determinação, coeficiente de determinação ajustado, Critério de informação de Akaike e Critério de informação Bayesiano de Schwarz) para selecionar o modelo mais adequado. Também foi realizada a análise técnica (conversão alimentar) e econômica (margem bruta de comercialização -MB) a partir de estimativas de pesos corporais e de consumo de ração do melhor modelo selecionado, nos pesos e idade de abate predeterminados. A curva de Gompertz e a equação de alometria em função da proteína corporal foram selecionadas para estimar os valores individuais dos pesos de cada boxe e avaliar os efeitos de sexo e de linhagem em cada sexo. Os coeficientes alométricos foram heterogônicos negativos para a deposição de água corporal e órgãos; e heterogônicos positivos para cinzas, gordura corporal, carcaça e cortes da carcaça. Os machos tiveram maior desenvolvimento corporal e dos componentes com maior precocidade, exceto para gordura corporal. Macho Cobb 500 apresentou peso superior de peito; macho Hubbard maior deposição de proteína corporal, sendo mais eficiente tecnicamente e Ross 308, macho e fêmea, foram mais precoces para crescimento corporal e para a maior parte dos componentes. Na análise econômica utilizando o modelo Gompertz observou-se que machos apresentaram melhor conversão alimentar e MB do que fêmeas e Ross 308, apesar de ter comportamento superior em crescimento e precocidade, não foi tão eficiente tecnicamente e/ou economicamente quanto às linhagens Cobb 500 e Hubbard Flex nas últimas pesagens. / The study was conducted to estimate the parameters, evaluate and compare the adjustments of body growth curves and the physical and chemical body components, lines of sexed broilers. 1848 day-old chicks in a completely randomized design in a factorial design with treatments in hierarchical factorial design with the factors: sex (male and female) and strains (Cobb 500, Ross 308 and Hubbard Flex) within each sex, a total of six treatments with six replicates of 50 birds each. The experimental diet attended the nutritional requirement for each sex. On the first day, eight animals of each strain and sex were slaughtered, obtaining the initial weight of the physical and chemical components and weekly birds and every boxing feeds were weighed for the feed intake data and body weight. According to the mean weight of each pen were made weekly slaughter, two or three animals (24 h of fasting) were obtained, weights: Body fasting, body fasting plucking, feathers, carcass, chest, thigh, drumstick, wing, heart, liver and gizzard. Other two birds (from average body weight) fasted were used to study deposition of nutrients on body weight plucking fasting and feathers, and samples of these characteristics were processed, homogenized and analyzed for dry matter, nitrogen, extract ethereal and ashes. The average curve parameters were estimated, as well as the allometric coefficients and used statistical criteria for goodness of fit (coefficient of determination, adjusted determination coefficient, Akaike information criterion and Bayesian information criterion of Schwarz) to select the most appropriate model. It was also carried out technical analysis (feed conversion) and economic (gross margin trading -GM) from body weights estimates and feed intake of the best model selected, the weight and age of predetermined slaughter. The Gompertz curve and the allometry equation as a function of body protein were selected to estimate individual values of each pen weights and evaluate the effects of sex and strain of each sex. The allometric coefficients were negative heterogônic for the deposition of body water and organs; and positive heterogônic for ashes, body fat, carcass and carcass cuts. Males had earlier higher body development and their components, except for body fat. Male Cobb 500 showed a higher weight breast and thigh, male Hubbard had greater deposition of body protein being more efficient and technically Ross 308, male and female, were earlier for body growth and most of their components. In the economic analysis using the Gompertz model it was observed that males had better feed conversion and GM than females and Ross strain 308, despite having higher growth and precocity, it was not as efficient technically and / or economically as the Cobb 500 and Hubbard Flex. Males had higher body development and components begin earlier, except for body fat. Male Cobb 500 showed superior weight breast; Male Hubbard had greater deposition of body protein being more efficient and technically Ross 308, male and female, were earlier for body growth and most of the components. In the economic analysis using the Gompertz model was observed that males had better feed conversion and MB than females and Ross strain 308, that despite having superior behavior on growth and earliness, this last line was not as efficient technically and / or economically as the lines Cobb 500 and Hubbard Flex in the last weighing.

The aluminum oxide growth rate for aluminum protected with 2.4 nm of aluminum fluoride has been determined. We show that a 2.4 nm aluminum fluoride layer does not prevent aluminum from oxidation but does significantly retard the oxide growth – decreasing the oxide layer thickness from 1 nm in less than an hour to 0.9 nm over 116 hours. Additionally, the optical constants for aluminum oxide growing under an aluminum fluoride barrier layer have been determined – showing an increase in absorption at high energies for Al2O3 forming at room temperature as compared to highly ordered Al2O3 formed at high temperatures.

Gene regulatory networks are composed of interconnected regulatory nodes created by regulatory factors of multiple types. All organisms finely tune gene expression in order to adapt to and survive within their current niche. Obligate parasitic bacteria are under extreme pressure to quickly and appropriately adapt their gene regulatory programs in order to survive within their given host. Borrelia burgdorferi is one such organism and persists in nature by alternating between two hosts; Ixodes spp. ticks and small vertebrate animals. These two hosts represent drastically different environments; requiring a unique gene regulatory program to survive and transmit between them. Microbiologists have long sought to better understand exactly what stimuli pathogens sense and how that information is relayed in to physiologic adaptation. In this work I aimed to examine two parts of this interesting field. First, I sought to better understand the stimuli B. burgdorferi sense in order to adapt to their hosts by testing several hypotheses centered on the general notion that B. burgdorferi senses both internal and external metabolic cues as primary signals for adaptation. I demonstrated that a second messenger system immediately downstream of a critical metabolic pathway is important during vertebrate infection and that a key regulator of virulence is itself regulated by a factor involved in DNA replication. Second, I sought to better define the topology of gene regulatory networks, known and unknown, that are important for the ability of the bacteria to adapt. The work in this section focus on the idea that B. burgdorferi gene regulatory networks are extremely complex and are not currently well defined in the literature. My studies revealed that B. burgdorferi possesses a large number of previously undefined regulatory targets, including extended 5’ and 3’ UTRs of known genes, and encodes several hundred-putative small non-coding RNAs. Furthermore, I demonstrate that two essential regulatory factors share substantial, independent, overlap in their regulons highlighting the still undefined complexity of regulatory networks at play in B. burgdorferi.

Although genomes are perhaps the single most important element of living systems, why they feature such striking variation and how this variation is maintained within and across natural populations remains unclear. One of the most common and important means by which genomic variation is generated is ploidy elevation. While polyploidy has been implicated in the remarkably successful radiations of angiosperms, teleost fish, and amphibians, the phenotypic consequences of changes in ploidy level are poorly understood, especially in animals. I use a large, multi-year common garden experiment to identify potential life history costs and benefits of polyploidy and asexual reproduction, a trait often associated with polyploidy, in Potamopyrgus antipodarum. This snail is well suited for studying ploidy variation and sex because diploid sexuals and triploid and tetraploid asexuals frequently coexist, allowing us to use comparisons of sexuals to asexuals and triploid to tetraploid asexuals to study both the effects of ploidy elevation and sex. I detected a strong negative correlation between growth rate and time to maturity and found that sexual P. antipodarum grew and matured significantly more slowly than the polyploid asexuals. Sexual P. antipodarum were also more likely to die before achieving reproductive maturity than their asexual counterparts. By contrast, there were no apparent life history differences between triploid and tetraploid asexuals, indicating that direct phenotypic benefits of ploidy elevation are unlikely to explain the relatively rapid growth and maturation of asexuals. My results suggest that ploidy elevation does not inevitably confer phenotypic consequences, that reproductive mode influences life history trait expression, and that sexual P. antipodarum persist in many natural populations in spite of substantial life history disadvantages.

<p>Population viability analysis (PVA) is commonly used in conservation biology to predict population viability in terms of population growth rate and risk of extinction. However, large data requirements limit the use of PVA for many rare and threatened species. This thesis examines the possibility of conducting a matrix model-based PVA for plants with limited data and provides some practical recommendations for reducing the amount of work required. Moreover, the thesis applies different forms of matrix population models to species with different life histories. Matrix manipulations on 37 plant species revealed that the amount of demographic data required can often be reduced using a smaller matrix dimensionality. Given that an individual’s fitness is affected by plant density, linear matrix models are unlikely to predict population dynamics correctly. Estimates of population size of the herb <i>Melampyrum sylvaticum</i> were sensitive to the strength of density dependence operating at different life stages, suggesting that in addition to identifying density-dependent life stages, it is important to estimate the strength of density dependence precisely. When a small number of matrices are available for stochastic matrix population models, the precision of population estimates may depend on the stochastic method used. To optimize the precision of population estimates and the amount of calculation effort in stochastic matrix models, selection of matrices and Tuljapurkar’s approximation are preferable methods to assess population viability. Overall, these results emphasize that in a matrix model-based PVA, the selection of a stage classification and a model is essential because both factors significantly affect the amount of data required as well as the precision of population estimates. By integrating population dynamics into different environmental and genetic factors, matrix population models may be used more effectively in conservation biology and ecology in the future.</p>

<p>Many engineering components reach a finite fatigue life well above 10⁹load cycles. Some examples of such components are found in airplanes, automobiles or high speed trains. For some materials the fatigue failures have lately been found to occur well after 10⁷ load cycles, namely in the Very High Cycle Fatigue (VHCF) range. This finding contradicted the established concept of fatigue limit for these materials, which postulates that having sustained 10⁷ load cycles the material is capable of enduring an infinite number of cycles provided that the service conditions are unchanged. With the development of modern ultrasonic fatigue testing equipment it became possible to experimentally establish VHCF behaviour of various materials. For most of them the existence of the fatigue limit at 10⁷ load cycles has been proved wrong and their fatigue strength continues to decrease with increasing number of load cycles.</p><p> </p><p>One important group of materials used for the production of high performance components subjected to the VHCF is tool steels. This study explores the VHCF phenomenon using experimental data of ultrasonic fatigue testing of some tool steel grades. The causes and mechanisms of VHCF failures are investigated by means of high resolution scanning electron microscopy, and in relation to the existing theories of fatigue crack initiation and growth. The main type of VHCF origins in steels are slag inclusions.</p><p>However, other microstructural defects may also initiate fatigue failure. A particular attention is paid to the fatigue crack initiation, as it has been shown that in the VHCF range crack formation consumes the majority of the total fatigue life. Understanding the driving forces for the fatigue crack initiation is a key to improve properties of components used for very long service lives. Finite element modelling of VHCF testing was added as an additional perspective to the study by enabling calculation of local stresses at the fatigue initiating defects.</p><p> </p><p> </p>