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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.
231

Crack Growth Rate and Crack Path in Adhesively Bonded Joints: Comparison of Creep, Fatigue and Fracture

Jhin, Minseok 20 November 2012 (has links)
The relationship between crack path and test method was examined by comparing the performance of adhesive-adherend combinations (six) in quasi-static fracture, mixed-mode fatigue, and creep crack growth. Crack paths in creep and quasi-static fracture were similar due to similar crack-tip plastic zone sizes in the epoxy adhesive even though the crack growth rates in creep were much smaller. Under condensed moisture and mixed-mode, creep and threshold fatigue tests produced interfacial failure. Under room-temperature dry environment, near threshold mixed-mode fatigue was interfacial, but was not in creep or quasi-static fracture. Smaller plastic zone size and crack path proximity to the interface that followed increased the sensitivity of near threshold, mixed-mode fatigue to surface properties. Therefore, the interfacial or cohesive failure of an adhesive system, which may judge the quality of the bond, can be a function of the test being conducted and may not be an absolute indicator of joint quality.
232

Near-threshold Fatigue of Adhesive Joints: Effect of Mode Ratio, Bond Strength and Bondline Thickness

Azari, Shahrokh 05 September 2012 (has links)
The main objective of the project was to establish a fracture-mechanics energy-based approach for the design of structural adhesive joints under cyclic loading. This required understanding how an adhesive system behaved near its fatigue threshold, and how the key factors affected this behavior in a fresh undegraded joint. The investigated factors were mode ratio (phase angle), substrate material, surface treatment and surface roughness (both affecting the bond strength), bondline thickness and load ratio. It was first required to understand how the adhesive system behaved under quasi-static loading by examining a fracture mechanics-based design approach for adhesive systems with different substrate materials and geometries. Experiments were initially performed to characterize the strength of aluminum and steel adhesive systems based on the fracture envelope, critical strain energy release rate as a function of the mode ratio. Ultimate failure loads of aluminum and steel adhesive joints, having different overlap end conditions and different geometries were then experimentally measured. These values were compared with the failure loads extracted from the fracture envelope. Considering the toughening behavior of the adhesive in the fracture mechanics analyses, a very good agreement (average of 6%) was achieved between the predictions and experiments for all types of overlap end conditions and geometries. Different fatigue threshold testing approaches, which are commonly used in the literature or suggested by the ASTM standard, were evaluated for the cracked and intact fillet joints. Based on the experimental and analytical studies, the most appropriate technique for fatigue testing and characterization of adhesive systems was suggested. Comparing the mixed-mode near-threshold behavior of different adhesive systems with the fracture behavior and fatigue mode-I and mixed-mode high crack growth rates showed the high sensitivity of the mixed-mode near-threshold fatigue to the subtle changes in the interfacial bond strength. In order to make a baseline for the design of adhesive joints under cyclic loading, similar to the previous fracture tests and following the energy-based approach, fatigue behavior was characterized as a function of the loading mode ratio for aluminum and steel adhesive joints. The effect of substrate material, surface treatment, bondline thickness, surface roughness and fatigue testing load ratio on the near-threshold fatigue behavior of adhesives joints was evaluated experimentally. The experimental observations were then explained using finite element modeling. To generalize the conclusions, the majority of experiments and studies covered a broad range of crack growth rates, as low as fatigue threshold and as high as 10-2 mm/cycle. Having understood the significant testing and design parameters, an adhesive system can be designed based on a safe cyclic load that produces an insignificant (for automotive industry) or reasonably low but known crack growth rate (for aerospace industry).
233

Effect Of Retrogression And Reaging Heat Treatment On Corrosion Fatigue Crack Growth Behavior Of Aa7050 Alloy

Akgun, Nevzat 01 September 2004 (has links) (PDF)
The effect of retrogression and reaging heat treatment on corrosion fatigue crack growth behavior on AA7050 T73651 aluminum alloy is investigated. CT (Compact Tension) specimens are prepared in LS direction for fatigue crack growth tests . Samples are solution heat treated at 477 &deg / C and aged at 120 &deg / C for 24 h (T6 condition). After that, samples are retrogressed at 200 &deg / C for times of 1, 5, 30, 55 and 80 minutes in a circulating oil bath. Then, samples are re-aged at 120 &deg / C for 24 h (T6 condition). Hardness measurements are taken at different retrogression times and at the end of the heat treatment. Fatigue crack growth tests are performed at as received condition and at different retrogression times with sinusoidal loading of R=0.1 and f=1 in both laboratory air and corrosive environment of 3.5% NaCl solution. The highest fatigue crack growth resistance is observed for 30 min. and 5 min. retrogression for laboratory air and corrosive environment respectively. It is concluded that RRA can successfully be used to improve fatigue performance of this alloy.
234

Crystallization Studies on a Bacillus licheniformis Alpha-amylase

Alex Chan Unknown Date (has links)
Proteins are important biological products with unique functions, annually produced at the hundreds of millions of dollars value on a worldwide basis. The application of crystallization for these materials primarily was led by structural biologists and crystallographers who are keen on obtaining large and well-ordered crystals for protein structure determination via X-ray diffraction. Usually for this, crystallization is done on a small scale by vapor diffusion using a supersaturated solution of the material. In the past decades, production crystallization has slowly received increasing attention for the large-scale recovery of proteins. Among the numerous products, an industrial enzyme (alpha-amylase) that is extensively involved in food processing and laundry products was chosen for examination due to the lack of relevant data in the literature and the potential industrial interest in crystallizing this material. The chosen alpha-amylase is a product of Genencor International (the Danisco division) and is derived from a genetically modified Bacillus licheniformis. In parallel to the underlying principles that govern the bulk crystallization of small molecules, the broad topics of investigation for this macromolecular material included determination of solubility, studies of nucleation thresholds, and investigation of crystal growth kinetics and special phenomena accompanying the crystallization process. All these studies were preceded by a series of characterization tests conducted for the material. On the whole, this study aimed to extend the existing fundamental knowledge of bulk crystallization for biological macromolecules. Specifically, it intended to enrich the solubility and crystallization kinetic data for the alpha-amylase. The experimental data of this study were all obtained at conditions in line with industrial practice, which included the use of moderate temperatures, mild pH conditions and simple inorganic salts ((NH4)2SO4, Na2SO4 and NaCl) in order for the findings to be transferred to the industry directly. In a 20 mM sodium phosphate buffer (with no added salts), alpha-amylase solubility increased with solvent temperature and had a minimum at pH between 6.4 and 7.1. A generalized equation (as a function of pH and temperature) was obtained to correlate the data. The three inorganic salts examined affected the alpha-amylase solubility in a different manner, both qualitatively and quantitatively. Evidently, the interaction effect of a salt varied with solution pH. This confirms the importance of studying solubility with the two or more condition parameters at the same time. With relevance to crystal growth, the metastable region of the material was relatively wide at (NH4)2SO4 and Na2SO4 concentrations corresponding to maximum solubility. For example, σSNT was 1.2  0.2 in solutions with 5 wt% ammonium sulfate at pH 7.0 and 25oC. A wide metastability range is useful for the practical operation of batch crystallizers as nucleation can be minimized. This range, however, diminished as the salt concentration increased beyond the maximum solubility points, imposing a limit on the range of salt concentration favorable for growth processes. In systems with no added salts at pH 7.0, the solution metastability was slightly higher at 10oC than at 40oC. This would suggest a future further examination of the salt system at a lower temperature, say of 10oC. To develop a batch crystallizer, the growth kinetic data of the material have to be known. Throughout the growth studies, the alpha-amylase crystals obtained were lozenge-shaped thin plates. Apparently, habit was not influenced by the crystallization conditions chosen. Similar to other proteins crystallized in bulk, the growth rate of alpha-amylase demonstrated a second-order dependence upon supersaturation. Importantly, the alpha-amylase demonstrated crystal growth rate dispersion (GRD) under all the conditions tested. To simplify the analysis of growth kinetic results, the seed crystals used were common history (CH) seeds whose growth rates are proportional to their sizes. The spread of growth rates (CV) was 0.54 for the unsieved CH seeds used. Due to GRD, growth rate coefficient data varied with crystal size. For instance, in solutions containing 5 wt% ammonium sulfate at pH 7.0 and 25oC, the growth rate coefficient for seed crystals initially at 20 m was 2.47 m/hr. This order of magnitude was equivalent to that of many other proteins. Although being small, industrial crystallization was feasible with these kinetics, as demonstrated by the sample design calculations included. To improve the design, it is recommended to further examine the solubility, metastability and growth kinetics of the above system at other temperatures to obtain a wider growth rate range. As the important phenomenon of growth rate dispersion has seldom been examined for protein and enzyme materials in the crystallization literature, this study is a significant contribution to this area.
235

Características de história de vida de peixes de pequeno porte sob o efeito de diferentes regimes hidrológicos em planície de inundação tropical

Tondato, Karina Keyla January 2013 (has links)
O presente trabalho tem como objetivo avaliar traços de história de vida de peixes de pequeno porte sob o efeito de diferentes regimes de inundação no Pantanal. As amostragens foram realizadas nas regiões Norte (Rio Cuiabá) e Sul do Pantanal (Rio Paraguai), que apresentam regimes hidrológicos diferenciados. Inicialmente, foram obtidos dados de 623 indivíduos da espécie Odontostilbe pequira no Pantanal Sul, para análise de estrutura populacional e traços reprodutivos. Não foi observada variação significativa na distribuição de comprimento entre os sexos. O período reprodutivo foi longo para ambos os sexos (10 meses), com maior intensidade entre os meses de Junho e Julho. Não ocorreu correlação entre o índice gonadossomático (IGS) de ambos os sexos com a temperatura da água e pluviosidade temporalmente. Os machos não apresentaram associação entre o IGS e o nível do rio, mas uma correlação marginalmente significativa foi observada nas fêmeas. Contudo, foi observado o efeito do nível histórico do rio sobre o IGS para ambos os sexos, indicando que o regime de inundação tem influência decisiva na atividade reprodutiva de O. pequira, proporcionando a ocorrência de desovas mesmo que a pluviosidade e temperatura apresentem baixos valores. O. pequira, pode ser caracterizada como uma espécie de “estratégia oportunista”, apresentando longo período reprodutivo, desova parcelada e elevada fecundidade, com atividade reprodutiva fortemente associada com o regime de inundação. Posteriormente, foram utilizados dados de comprimento de 977 indivíduos de O. pequira no Pantanal Sul, para análises adicionais de traços de história de vida entre os sexos. O comprimento assintótico (L∞) estimado para fêmeas foi maior (39,59mm) que para os machos (37,57mm). As fêmeas também apresentaram maior taxa de crescimento (k=0,93 ano-1) e mortalidade natural (Z=1,56 ano-1) em relação aos machos (k=0,82 ano-1; Z= 1,45 ano-1). Através das curvas de crescimento foram registrados 3 coortes completas para as fêmeas, com longevidade estimada em 3,22 anos, e, 4 coortes para os machos, com longevidade de 3,65 anos. O padrão de recrutamento foi longo para ambos os sexos, não sendo observada variação significativa na forma da distribuição do recrutamento entre os sexos. Constatamos correlação entre o recrutamento e o nível do rio para ambos os sexos, com pico de recrutamento em Julho e Junho para fêmeas e machos, respectivamente, corroborando com o período reprodutivo da espécie e com a associação com o regime de inundação no Pantanal Sul. Finalmente, foram obtidos dados de comprimento das espécies Bryconamericus exodon, Hyphessobrycon eques, O. pequira, Moenkhausia dichroura, Hypoptopoma inexpectatum e Eigemnannia trilineata, nas regiões norte e sul do Pantanal, para realizar as comparações intra e interespecífica. As espécies não apresentaram diferença significativa na forma de distribuição de comprimento entre as regiões. O L∞ das espécies apresentou variação intraespecífica entre as regiões, com os maiores valores para as populações da região norte (exceção, E. trilineata). A taxa de crescimento (k) e mortalidade (Z) apresentou variação intraespecífica entre as regiões, com quatro espécies (B. exodon, H. eques, O. pequira e M. dichroura) demonstrando menores k e Z, e maiores L∞ na região Norte, sugerindo que a região norte oferece condições mais favoráveis em relação à região Sul. Não ocorreu variação intraespecífica entre as regiões para o número de coortes e longevidade. O padrão de recrutamento não apresentou variação intraespecífica entre as regiões, apresentando longo período de recrutamento e picos para todas as espécies entre Junho e Agosto. Na região Norte, o padrão de recrutamento de quatro espécies (B. exodon, H. eques, M. dichroura e H. inexpectatum) não apresentou correlação significativa com o nível histórico do rio Cuiabá, entretanto, essas espécies apresentaram covariação negativa, além de duas espécies (O. pequira e E. trilineata) apresentarem correlação negativa significativa, apresentando picos de recrutamento com a diminuição do nível da água. Na região Sul, cinco espécies (B. exodon, H. eques, M. dichroura, H. inexpectatum e O. pequira) estiveram associadas significativamente com o nível histórico do rio Paraguai, com picos de recrutamento em níveis mais elevados de água, indicando que o regime de inundação tem influência decisiva no padrão de recrutamento (exceção, E. trilineata). Enfim, as espécies apresentaram variação intraespecífica na maioria dos traços de história de vida, mas não há ampla variação, inclusive no padrão de recrutamento que não se altera intra e interespecificamente, evidenciando tanto a força da ancestralidade de táxon (filogenia), como das condições ambientais locais regidas pelo regime de inundação, respectivamente. / The present study aimed to evaluate life history traits of small sized fish according to different flooding regimes in the Pantanal. Samplings were performed in Northern (Cuiabá River) and Southern Pantanal (Paraguai River), which present distinct hydrological regimes. First, data of 623 individuals of Odontostilbe pequira in Southern Pantanal were analyzed as for population structure and reproductive traits. No significant variation was found in length distribution between sexes. The reproductive period was long for both sexes (10 months), with higher intensity between June and July. No correlation was detected between the gonadosomatic index (GSI) of both sexes with water temperature and rainfall over time. Males presented no association between GSI and river water level, but a marginally significant correlation was observed for females. However, it was verified the effect of the historical river level on the GSI for both sexes, indicating that the flooding regime has a decisive influence on the reproductive activity of O. pequira, by promoting spawning even if rainfall and temperature present low values. O. pequira can be characterized as an opportunistic species, presenting a long reproductive period, multiple spawning and high fecundity with reproductive activity strongly associated with the flooding regime. Afterwards, length data from 977 individuals of O. pequira in Southern Pantanal were used for additional analysis on life history traits between the sexes. The asymptotic length (L∞) estimated for females was higher (39.59mm) than for males (37.57mm). Females also presented higher growth rate (k=0.93 year-1) and natural mortality (Z=1.56 year-1) than males (k=0.82 year-1; Z= 1.45 year-1). By means of growth curves, 3 cohorts were recorded for females, with longevity estimated at 3.22 years, and 4 cohorts for males, with longevity of 3.65 years. The recruitment pattern was long for both sexes, without significant variation in recruitment distribution between the sexes. There was a correlation between recruitment and river water level for both sexes, with a recruitment peak in July and June for females and males, respectively, corroborating with the reproductive period of the species and with the association with the flooding regime in Southern Pantanal. At last, length data of Bryconamericus exodon, Hyphessobrycon eques, O. pequira, Moenkhausia dichroura, Hypoptopoma inexpectatum and Eigemnannia trilineata, in Northern and Southern Pantanal, were used for intra- and interspecific comparisons. Species have not presented significant difference in length distribution between regions. The L∞ of species exhibited an intraspecific variation between the regions, with higher values of the populations from the Northern Pantanal (except for E. trilineata). The growth (k) and mortality (Z) rates presented intraspecific variation between the regions, with four species (B. exodon, H. eques, O. pequira and M. dichroura) revealing lower values of k and Z, and higher L∞ values in Northern Pantanal, suggesting that this region provides more favorable conditions than the Southern region. There were no intraspecific variations between the regions for the number of cohorts and longevity. The recruitment pattern also had no intraspecific variation between the regions, presenting a long recruitment period and greater peak for all species between June and August. On the Northern region, the recruitment pattern of four species (B. exodon, H. eques, M. dichroura and H. inexpectatum) showed no significant correlation with historical level of the Cuiabá River, but these species presented a negative covariation; besides that, two species (O. pequira and E. trilineata) presented a significant negative correlation, with recruitment peaks with decreasing water level. In the Southern Pantanal, five species (B. exodon, H. eques, M. dichroura, H. inexpectatum and O. pequira) have been significantly associated with the historical level of the Cuiabá River, with recruitment peaks at higher water levels, pointing out that the flooding regime has a key influence on the recruitment pattern (except for E. trilineata). Finally, species presented intraspecific variations in most of life history traits, but there is no wide variation, including in the recruitment pattern that does not change intra- and interspecies, evidencing both the control of the taxa ancestry (phylogeny) and of local environmental conditions ruled by the flooding regime, respectively.
236

Impacto dos investimentos socioambientais sobre a taxa de crescimento de empresas brasileiras / Impact of social and environmental investments on growth rate of brazilian companies

Ferreira, Vanessa Elionara Souza 26 February 2016 (has links)
Submitted by Socorro Pontes (socorrop@ufersa.edu.br) on 2017-01-24T20:32:51Z No. of bitstreams: 1 VanessaESF_DISSERT.pdf: 1090600 bytes, checksum: 347527e99ec32b58c42ccca68378c3c3 (MD5) / Made available in DSpace on 2017-01-24T20:32:51Z (GMT). No. of bitstreams: 1 VanessaESF_DISSERT.pdf: 1090600 bytes, checksum: 347527e99ec32b58c42ccca68378c3c3 (MD5) Previous issue date: 2016-02-26 / The attention focused on actions involving social responsibility by companies has been an increasingly common theme in literature. The current economic climate has required of organizations a more ethical and focused on social and environmental issues approach, going beyond traditional financial matters. More than a social function of organizations, social and environmental investments now represent a competitive strategy. Several studies have examined the impact of such investments on the economic performance of organizations, but there is no consensus about its importance and level of relationship. In this sense, the present study aims to investigate the relationship between social and environmental investments and the economic growth rate of Brazilian companies. For that, was collected on a database called “Balanço Social” economic data from a sample of 130 companies, with publications over the period between 2000 and 2008, and based on the data panel and with the help of a statistical tool was estimated a regression model seeking the visualization of the ratio between the environmental investments and economic performance metrics, such as the rate of operational and net results of the firm. Although the relationship between the external social investments and the applied growth rates has been to a pattern of the U-shaped curve, the internal social and environmental investments showed, as expected, a pattern of an inverse U-shaped curve, as presented by Kuznets (1955), based in which it was possible to verify the level of investment that maximizes the performance of the firm. Through the knowledge of such values can be identified which companies operate at levels below the 'optimal level', suggesting the growth rate required to reach the equilibrium levels / A atenção voltada para ações que envolvam responsabilidade social por parte das empresas tem sido um tema cada vez mais recorrente na literatura. O cenário econômico atual tem exigido das organizações uma postura mais ética e voltada para as questões socioambientais, indo além das questões financeiras tradicionais. Mais do que uma função social das organizações, os investimentos socioambientais passaram a representar uma estratégia competitiva. Diversos estudos têm analisado os impactos de tais investimentos sobre o desempenho econômico das organizações, porém não existe um consenso quanto a sua importância e nível de relação. Nesse sentido, o presente estudo tem como objetivo verificar a relação entre os investimentos socioambientais e a taxa de crescimento econômico de empresas brasileiras. Para isso, foi coletado no Balanço Social dados econômicos de uma amostra de 130 empresas, com publicações ao longo do período entre 2000 e 2008, e a partir dos dados em painel e com o auxílio de uma ferramenta estatística foi estimado um modelo de regressão buscando a visualização da relação entre os investimentos socioambientais e métricas de desempenho econômico, tais como a taxa dos resultados operacionais e líquidos da firma. Embora a relação entre os investimentos sociais externos e as taxas de crescimento aplicadas tenha consistido em um padrão no formato de uma curva U, os investimentos sociais internos e ambientais apresentaram, conforme esperado, um padrão no formato de uma curva U-invertida, segundo apresentado por Kuznets (1955), com base na quais foi possível verificar o nível de investimento que maximiza o desempenho da firma. Tomando conhecimento de tais valores podem-se identificar quais empresas operam em níveis abaixo do nível ‘ótimo’, sugerindo a taxa de crescimento necessária para alcançar os níveis de equilíbrio / 2017-01-24
237

Efeito do peso ao nascer e ingestão de colostro na mortalidade e desempenho de leitões após a uniformização em fêmeas de diferentes ordens de parição / Effect of birth weight and colostrum intake on mortality and performance of piglets after cross-fostering in sows of different parities

Ferrari, Cristina Vicente January 2013 (has links)
O objetivo do estudo foi avaliar o efeito do peso ao nascer e ingestão de colostro na mortalidade e desempenho dos leitões levando em conta a ordem de parto das mães biológicas e adotivas. A ingestão de colostro do nascimento até as 24 horas de vida foi estimada em 300 leitões de primíparas e 300 leitões de multíparas através de pesagem ao nascimento e as 24 h de vida. Estes leitões foram uniformizados em 25 primíparas e 25 multíparas com 25,9 ± 0,09 h após o nascimento. A concentração de imunoglobulina G (IgG) no soro foi determinada nas fêmeas após o final do parto e nos leitões antes da uniformização (24 h após o parto), aos 10 e 20 dias de vida. Leitões de primíparas consumiram menos colostro (P= 0,0027) que leitões de multíparas, mas a concentração de IgG no soro dos leitões as 24 h de vida foi semelhante (P> 0,05). O risco de mortalidade até 42 dias de vida não foi afetado pela ordem de parto das mães biológicas ou adotivas (P> 0,05). Maior chance de mortalidade foi observada em leitões de baixo (LW - 1.10–1.2 kg) e intermediário (IW - >1.2–1.3 kg) peso ao nascer que consumiram ≤150 g de colostro comparados a leitões pesados (HW - >1.3 kg) que consumiram >250 g de colostro. Leitões HW tiveram maior peso aos 20, 28 e 42 dias de vida (P< 0,05) que leitões LW, mesmo quando consumiram a mesma quantidade de colostro. A ordem de parto da mãe biológica não teve efeito no desempenho dos leitões até 42 dias de vida (P>0,05). Leitões amamentados por multíparas tiveram maior peso que aqueles amamentados por primíparas. Leitões que morreram até 42 dias de vida tinham menor (P< 0,05) peso ao nascer, ingestão de colostro e IgG no soro as 24 h de vida comparados com leitões que sobreviveram, e estes menores valores foram também observados em leitões com baixo desempenho (<9.5 kg) comparados com leitões de alto desempenho (>9.5 kg). Não houve diferença entre IgG no soro aos 10 e 20 dias de vida (P= 0,3461) entre leitões com baixo e alto desempenho. Em conclusão, leitões LW são mais dependentes da ingestão de colostro que leitões HW para assegurar a sua sobrevivência e melhor desempenho até os 42 dias de vida. A sobrevivência e o crescimento não são afetados pela ordem de parto das mães biológicas, enquanto que leitões amamentados por fêmeas multíparas possuem melhor desenvolvimento que aqueles amamentados por fêmeas primíparas. / The objective of this study was to evaluate the effect of the birth weight and colostrum intake on mortality and growth performance of piglets until 42 days of age, also taking into account the parity order of the biological and foster dams. Colostrum intake from birth to 24 h after birth was estimated in 300 piglets each from primiparous and multiparous dams by weighing at birth and 24 h of age. These piglets were then cross-fostered in 25 primiparous and 25 multiparous sows at 25.9 ± 0.09 h after farrowing. The concentration of serum immunoglobulin G (IgG) was determined in the sows after the end of farrowing and in the piglets before cross-fostering (24 h after farrowing), at 10 and 20 days of age. Piglets from primiparous consumed less colostrum (P< 0.003) than piglets from multiparous dams, but their serum IgG concentrations at 24 h after birth were similar (P> 0.05). The risk of mortality until 42 days of age was not affected by the parity order of biological or foster dams (P> 0.05). Higher odds of mortality were observed in piglets of low (LW - 1.10–1.2 kg) and intermediate (IW - >1.2–1.3 kg) birth weight that consumed ≤150 g of colostrum compared to heavy piglets (HW - >1.3 kg) that consumed >250 g colostrum. HW piglets at birth had higher weight at 20, 28 and 42 days of age (P< 0.05) than LW piglets at birth, even when consuming the same amount of colostrum. The parity order of the biological dam had no effect on the performance of piglets until 42 days of age (P> 0.05). Piglets suckled by multiparous foster dams showed higher weight than those suckled by primiparous sows. Piglets that died before 42 days of age had lower (P< 0.05) birth weight, colostrum intake and serum IgG at 24 h after birth compared to surviving piglets, and these lower values were also observed in piglets with low (<9.5 kg) performance compared to high (>9.5 kg) performance piglets. There were no differences in serum IgG concentrations at 10 and 20 days of age (P= 0.346) between high and low performance piglets. In conclusion, LW piglets are more dependent on colostrum intake than HW piglets to assure higher survival and better development up to 42 days of age. Survival and growth are not affected by the parity order of the biological dam, whereas piglets suckled by multiparous sows have better development than those suckled by primiparous sows.
238

Características de história de vida de peixes de pequeno porte sob o efeito de diferentes regimes hidrológicos em planície de inundação tropical

Tondato, Karina Keyla January 2013 (has links)
O presente trabalho tem como objetivo avaliar traços de história de vida de peixes de pequeno porte sob o efeito de diferentes regimes de inundação no Pantanal. As amostragens foram realizadas nas regiões Norte (Rio Cuiabá) e Sul do Pantanal (Rio Paraguai), que apresentam regimes hidrológicos diferenciados. Inicialmente, foram obtidos dados de 623 indivíduos da espécie Odontostilbe pequira no Pantanal Sul, para análise de estrutura populacional e traços reprodutivos. Não foi observada variação significativa na distribuição de comprimento entre os sexos. O período reprodutivo foi longo para ambos os sexos (10 meses), com maior intensidade entre os meses de Junho e Julho. Não ocorreu correlação entre o índice gonadossomático (IGS) de ambos os sexos com a temperatura da água e pluviosidade temporalmente. Os machos não apresentaram associação entre o IGS e o nível do rio, mas uma correlação marginalmente significativa foi observada nas fêmeas. Contudo, foi observado o efeito do nível histórico do rio sobre o IGS para ambos os sexos, indicando que o regime de inundação tem influência decisiva na atividade reprodutiva de O. pequira, proporcionando a ocorrência de desovas mesmo que a pluviosidade e temperatura apresentem baixos valores. O. pequira, pode ser caracterizada como uma espécie de “estratégia oportunista”, apresentando longo período reprodutivo, desova parcelada e elevada fecundidade, com atividade reprodutiva fortemente associada com o regime de inundação. Posteriormente, foram utilizados dados de comprimento de 977 indivíduos de O. pequira no Pantanal Sul, para análises adicionais de traços de história de vida entre os sexos. O comprimento assintótico (L∞) estimado para fêmeas foi maior (39,59mm) que para os machos (37,57mm). As fêmeas também apresentaram maior taxa de crescimento (k=0,93 ano-1) e mortalidade natural (Z=1,56 ano-1) em relação aos machos (k=0,82 ano-1; Z= 1,45 ano-1). Através das curvas de crescimento foram registrados 3 coortes completas para as fêmeas, com longevidade estimada em 3,22 anos, e, 4 coortes para os machos, com longevidade de 3,65 anos. O padrão de recrutamento foi longo para ambos os sexos, não sendo observada variação significativa na forma da distribuição do recrutamento entre os sexos. Constatamos correlação entre o recrutamento e o nível do rio para ambos os sexos, com pico de recrutamento em Julho e Junho para fêmeas e machos, respectivamente, corroborando com o período reprodutivo da espécie e com a associação com o regime de inundação no Pantanal Sul. Finalmente, foram obtidos dados de comprimento das espécies Bryconamericus exodon, Hyphessobrycon eques, O. pequira, Moenkhausia dichroura, Hypoptopoma inexpectatum e Eigemnannia trilineata, nas regiões norte e sul do Pantanal, para realizar as comparações intra e interespecífica. As espécies não apresentaram diferença significativa na forma de distribuição de comprimento entre as regiões. O L∞ das espécies apresentou variação intraespecífica entre as regiões, com os maiores valores para as populações da região norte (exceção, E. trilineata). A taxa de crescimento (k) e mortalidade (Z) apresentou variação intraespecífica entre as regiões, com quatro espécies (B. exodon, H. eques, O. pequira e M. dichroura) demonstrando menores k e Z, e maiores L∞ na região Norte, sugerindo que a região norte oferece condições mais favoráveis em relação à região Sul. Não ocorreu variação intraespecífica entre as regiões para o número de coortes e longevidade. O padrão de recrutamento não apresentou variação intraespecífica entre as regiões, apresentando longo período de recrutamento e picos para todas as espécies entre Junho e Agosto. Na região Norte, o padrão de recrutamento de quatro espécies (B. exodon, H. eques, M. dichroura e H. inexpectatum) não apresentou correlação significativa com o nível histórico do rio Cuiabá, entretanto, essas espécies apresentaram covariação negativa, além de duas espécies (O. pequira e E. trilineata) apresentarem correlação negativa significativa, apresentando picos de recrutamento com a diminuição do nível da água. Na região Sul, cinco espécies (B. exodon, H. eques, M. dichroura, H. inexpectatum e O. pequira) estiveram associadas significativamente com o nível histórico do rio Paraguai, com picos de recrutamento em níveis mais elevados de água, indicando que o regime de inundação tem influência decisiva no padrão de recrutamento (exceção, E. trilineata). Enfim, as espécies apresentaram variação intraespecífica na maioria dos traços de história de vida, mas não há ampla variação, inclusive no padrão de recrutamento que não se altera intra e interespecificamente, evidenciando tanto a força da ancestralidade de táxon (filogenia), como das condições ambientais locais regidas pelo regime de inundação, respectivamente. / The present study aimed to evaluate life history traits of small sized fish according to different flooding regimes in the Pantanal. Samplings were performed in Northern (Cuiabá River) and Southern Pantanal (Paraguai River), which present distinct hydrological regimes. First, data of 623 individuals of Odontostilbe pequira in Southern Pantanal were analyzed as for population structure and reproductive traits. No significant variation was found in length distribution between sexes. The reproductive period was long for both sexes (10 months), with higher intensity between June and July. No correlation was detected between the gonadosomatic index (GSI) of both sexes with water temperature and rainfall over time. Males presented no association between GSI and river water level, but a marginally significant correlation was observed for females. However, it was verified the effect of the historical river level on the GSI for both sexes, indicating that the flooding regime has a decisive influence on the reproductive activity of O. pequira, by promoting spawning even if rainfall and temperature present low values. O. pequira can be characterized as an opportunistic species, presenting a long reproductive period, multiple spawning and high fecundity with reproductive activity strongly associated with the flooding regime. Afterwards, length data from 977 individuals of O. pequira in Southern Pantanal were used for additional analysis on life history traits between the sexes. The asymptotic length (L∞) estimated for females was higher (39.59mm) than for males (37.57mm). Females also presented higher growth rate (k=0.93 year-1) and natural mortality (Z=1.56 year-1) than males (k=0.82 year-1; Z= 1.45 year-1). By means of growth curves, 3 cohorts were recorded for females, with longevity estimated at 3.22 years, and 4 cohorts for males, with longevity of 3.65 years. The recruitment pattern was long for both sexes, without significant variation in recruitment distribution between the sexes. There was a correlation between recruitment and river water level for both sexes, with a recruitment peak in July and June for females and males, respectively, corroborating with the reproductive period of the species and with the association with the flooding regime in Southern Pantanal. At last, length data of Bryconamericus exodon, Hyphessobrycon eques, O. pequira, Moenkhausia dichroura, Hypoptopoma inexpectatum and Eigemnannia trilineata, in Northern and Southern Pantanal, were used for intra- and interspecific comparisons. Species have not presented significant difference in length distribution between regions. The L∞ of species exhibited an intraspecific variation between the regions, with higher values of the populations from the Northern Pantanal (except for E. trilineata). The growth (k) and mortality (Z) rates presented intraspecific variation between the regions, with four species (B. exodon, H. eques, O. pequira and M. dichroura) revealing lower values of k and Z, and higher L∞ values in Northern Pantanal, suggesting that this region provides more favorable conditions than the Southern region. There were no intraspecific variations between the regions for the number of cohorts and longevity. The recruitment pattern also had no intraspecific variation between the regions, presenting a long recruitment period and greater peak for all species between June and August. On the Northern region, the recruitment pattern of four species (B. exodon, H. eques, M. dichroura and H. inexpectatum) showed no significant correlation with historical level of the Cuiabá River, but these species presented a negative covariation; besides that, two species (O. pequira and E. trilineata) presented a significant negative correlation, with recruitment peaks with decreasing water level. In the Southern Pantanal, five species (B. exodon, H. eques, M. dichroura, H. inexpectatum and O. pequira) have been significantly associated with the historical level of the Cuiabá River, with recruitment peaks at higher water levels, pointing out that the flooding regime has a key influence on the recruitment pattern (except for E. trilineata). Finally, species presented intraspecific variations in most of life history traits, but there is no wide variation, including in the recruitment pattern that does not change intra- and interspecies, evidencing both the control of the taxa ancestry (phylogeny) and of local environmental conditions ruled by the flooding regime, respectively.
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Ontogenetický vývoj a behaviorální projevy ledňáka modrokřídlého (Dacelo leachii) v zájmovém chovu / Ontogenetic development and behaviour of captive Blue-winged Kookaburra (\kur{Dacelo leachii})

SVOBODOVÁ, Yveta January 2018 (has links)
The Blue-winged Kookaburra is among the species of birds in which there is a sex dimorphism manifested in two characteristics. The first is the more pronounced coloration of the tail of the male; the second is the weight difference between the sexes. The female is about 70 - 100 grams heavier than the male. These differences do not occur earlier than after the first year of life. Although globally, there are 133 individuals of the Blue-winged Kookaburra (61 males, 58 females, 14 young) in human care in 45 institutions in 5 regions, it is successfully reproduced in only 9 institutions. Ostrava Zoo, as one of the three zoos and zoo parks in the world, keeps the Blue-winged Kookaburras in a group of eight, which is the optimal number of individuals forming a breeding cooperative group. In breeding seasons 2011 - 2016, Ostrava Zoo showed excellent results in breeding these Coraciiformes, with 15 successfully raised individuals. It therefore provided the data, together with Prague Zoo. This diploma thesis is a summary of own ethological observations at Ostrava Zoo and of a short observation at Prague Zoo. Summarizing the data from these two zoos, the thesis assesses weight differences of fertilized and unfertilized eggs, ontogenesis, growth rate and sex of the Blue-winged Kookaburras. On the basis of the growth and weight differences between the sexes, it deals with the sex determination of the young. It further describes social behaviour and vocalization within a breeding group with a predominance of females, evaluates general group relationships, and compares the results with a wild population
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INFLUÊNCIA DA AÇÃO DO TRÁFEGO NO CUSTO DE CONSTRUÇÃO E RESTAURAÇÃO DE PAVIMENTOS ASFÁLTICOS / THE INFLUENCE OF THE ACTION OF TRAFFIC IN THE COST OF CONSTRUCTION AND RESTORATION IN ASPHALT FLOORING

Klamt, Rodrigo André 16 December 2014 (has links)
It is known that traffic in Brazil has increased significantly in recent years due to high dependence on road transportation. In addition, commercial vehicles come to market with new settings, with more axles and greater cargo capacity; also as a function of legislation, that currently tolerates an overload of 10% per axle, when the vehicle is within the 5% of limit for the total gross weight (TGW). Consequently, there has been a considerable increase in the degradation of our road network. In this context, the present study aims to evaluate effects caused by the action of traffic in the cost of flexible pavements, focusing on aspects related to growth rate and excess load. Thus, the projection of traffic volume during a given period of time should express the current growth rates of cargo, so, the commercial vehicles; and it was also examined, if these indices are correlated with the Brazilian GDP and with the truck sales in the country. In another step, it was proposed a case study by selecting one of the toll plazas of the study to perform the sizing of the pavement by using DNIT method and mechanistic-empirical methods in order to analyze the influence of overloading in commercial vehicles in the design and in the cost of construction of the asphalt floors. For the same case study, it was performed the sizing and the calculation of the cost of paving restoration. Thus, in this study, it was concluded that the real traffic growth rate in the regions investigated are considerably above the one proposed by DNIT, which is 3.00%. The average growth rate of the study was 7.16%. The correlation between the rate of growth, the GDP and the truck sales was weak. The influence of overloading in the number N was in the order of 23.11% if compared the scenarios from the minor to the larger load. As for the DNIT method for different values of subgrade CBR (4%, 10% and 16%) the thickness of coating was the same for all loads, reaching the upper limit of the method in 12.5cm. By the mechanistic-empirical analysis, the one that showed to be more conservative was the comparison of the methods FHWA x Asphalt; with higher coating thickness (up to 16 cm) depending on fatigue and permanent deformation, while setting a higher execution cost, which increases the higher is the overload on commercial vehicles, being the maximum difference of cost depending on the cargo, in the order of R$ 158,231.00 (6.18%) per kilometer of pavement. As for the restoration, it was possible to realize that the increase in percentage of commercial vehicles and overloading in these vehicles causes a decrease in the allowable deflection and, consequently, an increase in thickness of reinforcement. It was observed a need of strengthen in all scenarios of loading for all characteristic deflections studied. The highest values of reinforcement thickness were for Dc equal to 125 (10−2mm) with 19 cm. The difference in the cost in function of the loading was R$ 51,450.00 (4.95%) per kilometer of pavement. The survey allowed obtain real parameters for subsequent interventions on existing roads; as well as to support new designs of road engineering. / Sabe-se que o tráfego no Brasil tem aumentado de forma significativa nos últimos anos devido à alta dependência do modo rodoviário. Além disso, os veículos comerciais surgem no mercado com novas configurações, com mais eixos e com maior capacidade de carga, em função também da legislação, que atualmente tolera sobrecarga por eixo de 10%, quando o veículo está dentro dos 5% de limite para o peso bruto total (PBT). Como consequência disso, tem-se um aumento considerável na degradação de nossa malha rodoviária. Neste âmbito, o presente estudo tem por objetivo avaliar efeitos provocados pela ação do tráfego no custo de pavimentos flexíveis, focando em aspectos relacionados a taxa de crescimento e excesso de carga. Assim, a projeção do volume de tráfego durante um dado período de tempo deverá exprimir os índices de crescimento atual da movimentação de cargas, portanto, dos veículos comerciais; procurou-se analisar, também, se tais índices se correlacionam com o PIB e com a venda de caminhões do país. Em outra etapa foi proposto um estudo de caso selecionando uma das praças do estudo para realizar o dimensionamento do pavimento pelo método do DNIT e por métodos empírico-mecanísticos a fim de analisar a influência da sobrecarga em veículos comerciais no dimensionamento e no custo da construção do pavimento. Para o mesmo estudo de caso foi realizado o dimensionamento e cálculo do custo de restauração do pavimento. Dessa forma, com este estudo, concluiu-se que a taxa de crescimento de tráfego real das regiões estudadas estão consideravelmente acima da proposta pelo DNIT, que é de 3,00%. A taxa de crescimento média global do estudo foi de 7,16%. A correlação entre a taxa de crescimento com o PIB e com a venda de caminhões foi fraca. A influência da sobrecarga no número N foi na ordem de 23,11% se comparados os cenários de menor para o maior carregamento. Quanto ao método do DNIT para diferentes valores de CBR de subleito (4%, 10% e 16%) a espessura de revestimento foi a mesma para todos os carregamentos, atingindo o limite superior do método em 12,5cm. Pela análise empírico-mecanística, a que se mostrou mais conservadora foi a comparação dos métodos FHWA x Asphalt Institute, com maiores valores de espessura de revestimento (até 16 cm) em função da fadiga e deformação permanente, apresentando também um maior custo de execução, o qual aumenta quanto maior a sobrecarga em veículos comerciais, sendo a diferença máxima de custo em função do carregamento na ordem de R$ 158.231,00 (6,18%) por quilômetro de pavimento. Quanto às restaurações, foi possível perceber que o aumento da porcentagem de veículos comerciais e sobrecarga nestes veículos ocasiona diminuição da deflexão admissível e, como consequência, um aumento na espessura de reforço. Verificou-se a necessidade de reforço em todos os cenários de carregamento para todas as deflexões características estudadas. Os maiores valores de espessura de reforço foram para Dc igual a 125 (10−2mm) com 19 cm. A diferença no custo em função do carregamento foi da ordem de R$ 51.450,00 (4,95%) por quilômetro de pavimento. A pesquisa permitiu obter parâmetros reais para posteriores intervenções nas rodovias existentes bem como para subsidiar novos projetos de engenharia rodoviária.

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