• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 56
  • 26
  • 4
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 149
  • 27
  • 27
  • 21
  • 20
  • 17
  • 15
  • 14
  • 13
  • 12
  • 12
  • 12
  • 11
  • 11
  • 10
  • 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.
121

Secagem de hidrolisado protéico de pele de cação por atomização = otimização do processo de hidrólise e avaliação das características físico-químicas do pó / Spray drying of shark protein hydrolysate : hydrolysis process optimization and evaluation of the physicochemical powder characteristics

Rodríguez Díaz, Julio César 17 August 2018 (has links)
Orientador: Míriam Dupas Hubinger / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-17T11:13:22Z (GMT). No. of bitstreams: 1 RodriguezDiaz_JulioCesar_M.pdf: 3275088 bytes, checksum: 4baa128a0e7dc07566683d567b97b97c (MD5) Previous issue date: 2011 / Resumo: O presente trabalho teve como objetivo a obtenção de hidrolisado protéico de pele de cação em pó pelos processos de hidrólise enzimática e secagem por atomização. Na primeira etapa, foi estudado o processo de hidrólise utilizando a enzima comercial ProtamexTM, visando a otimização do processo para a recuperação de peptídeos de baixo peso molecular. A influência da temperatura, do pH e da relação Enzima/Substrato sobre o grau de hidrólise, recuperação de proteína e cinética enzimática foram avaliadas. As condições ótimas de processo foram fixadas em: 51 °C, 4,0% p/p de enzima e pH 7,1. Nessas condições, o hidrolisado obtido foi caracterizado em termos de composição química, composição de aminoácidos e distribuição de tamanho de peptídeo. O grau de hidrólise atingiu 19,3%, recuperou-se 90,3% do total da proteína presente na matéria-prima e o peso molecular foi inferior a 6,5 kDa. Na segunda etapa do projeto, foi avaliada a influência das variáveis do processo de secagem por atomização sobre as propriedades físico-químicas e antioxidantes do hidrolisado protéico de pele de cação em pó, usando maltodextrina (DE=10) como agente carreador. A temperatura do ar e a concentração de agente carreador foram variadas. As respostas analisadas foram a umidade final, a atividade de água, a densidade aparente, a higroscopicidade, o tamanho de partícula e a capacidade antioxidante, determinada pelos métodos de redução do íon férrico (FRAP) e captura do radical catiônico ABTS+0 (TEAC). Os resultados mostraram que a adição de maltodextrina contribuiu significativamente para obtenção de partículas com menor umidade e higroscopicidade e maiores tamanhos de partícula e densidade aparente. Além disso, quanto maior foi a concentração de maltodextrina adicionada, maiores foram os valores de capacidade antioxidante, provavelmente devido à formação de compostos de Maillard durante a secagem / Abstract: The objetive of the present work was to obtain a shark skin protein hydrolysate powder by enzymatic hydrolysis and spray drying. In the first part of this work was studied the enzymatic hydrolysis process by using the commercial enzyme ProtamexTM, aiming the process optimization for recovery of low molecular weight peptides. The influence of temperature, pH and Enzyme/Substrate ratio on the degree of hydrolysis, protein recovery and enzymatic kinetics was evaluated. Optimal conditions were established at: 51°C, 4.0% p/p of enzyme and pH of 7.1. At these conditions, protein hydrolysate was characterized with respect to chemical composition, amino acid composition and peptide size distribution. Degree of hydrolysis achieved 19.3%, 90.3% of total protein was recovered and peptide size was lower than 6,5 kDa. In the second part of the project, the influence of spray drying variables process on physicochemical and antioxidant properties of shark skin protein hydrolysate powders, using maltodextrin (DE=10) as a carrier agent, was evaluated. Air temperature and maltodextrin concentration were varied. The responses analyzed were the final moisture content, water activity, bulk density, hygroscopicity, particle size distribution and antioxidant capacity determined by ferric reduction antioxidant power (FRAP) and ABTS+0 radical cation capture (TEAC) assays. Results showed that maltodextrin addition significantly contributed to obtaining particles with less moisture content, lower hygroscopicity and higher particle size and bulk density. Besides, antioxidant capacity was increased as increasing of maltodextrin concentration, probably due to the formation of Maillard compounds during drying process / Mestrado / Mestre em Engenharia de Alimentos
122

Jaws: Creating the Myth of the Man-Eating Machine

Castaldo Lundén, Elizabeth January 2012 (has links)
Jaws(Universal Studios, 1975) set a new standard for Hollywood film production byintroducing the concept of “summer blockbuster,” for a film that changed the way inwhich people thought about sharks. 37 years after the release of the movie, the idea of sharks as ferocious man-hunters still looms large in public opinion. Thisconceptualization of sharks as ruthless killers is mythical rather than factual, and thisresearch tracks the mechanisms that propelled the idea deep into popular culture.The dissertation addresses the problematics of media constructions through a casestudy of the movie Jawsdeparting from its production process, and by applyingBarbara Klinger’s interpretation of “epiphenomena.” The thesis studies how cinematravels into popular culture, by following the traces of the movie into other media, andits dialogue with the surrounding texts generated by PR, marketing andmerchandising; simultaneously, the thesis seek to demonstrate the connection between the movie as mythmaker and the stigmatized portrayal of sharks.
123

Conservation outcomes and sustainability of whale shark tourism in the Philippines

Ziegler, Jackie 01 May 2019 (has links)
Biodiversity loss is one of the major environmental threats facing the planet. Incentive-based conservation is one means to reduce human pressure on wildlife by providing economic incentives for resource-dependent people to protect the environment. Marine wildlife tourism is one of the fastest growing tourism sectors globally and is viewed as an important incentive-based approach for achieving marine conservation goals. However, few studies have linked participation in the provisioning of marine wildlife tourism activities with positive social and ecological conservation outcomes. The goal of this dissertation is to provide greater understanding of the conservation value of marine wildlife tourism using whale shark tourism as a case study with a main focus on social conservation outcomes amongst tourism providers. Positive changes in perceptions, attitudes and values towards target species and their environments can be an important element of incentive-based conservation. The study has the following objectives: (1) to assess the status of the global whale shark tourism industry, including types (e.g., captive, non-captive), real and potential impacts, conservation value and management challenges and best practices; (2) to examine the ethics of provisioning whale sharks in Oslob, Philippines, the largest, non-captive viewing site in the world; (3) to determine if working in ecotourism changed the attitudes and behaviours of locals towards whale sharks and the ocean, and if tourism type affects those outcomes; (4) to assess the marine wildlife value orientations of locals working in whale shark tourism to achieve greater understanding of the factors influencing their conservation attitudes and behaviours; (5) to explore the potential long-term impacts of poorly conceived incentive-based conservation projects on social and ecological conservation outcomes; and (6) to re-examine and update the conceptual and theoretical background for wildlife tourism in light of the findings of this study. Methods include a comprehensive literature review, tourist surveys, social media content analysis, and interviews with locals working in whale shark tourism at four sites in the Philippines. Results suggest that marine wildlife tourism can play an important role in changing locals’ attitudes and behaviours towards the focal species and habitat; however, smaller-scale, more established sites had greater conservation value than the mass tourism or failed sites suggesting that small-scale, community-based ecotourism is the best approach to meeting conservation goals of marine wildlife tourism. Yet, few tourism sites meet these standards. Global standards are needed to ensure whale shark tourism activities meet desired conservation goals. Such standards should include management requirements (e.g., licensing, mandatory education program) and interaction guidelines (e.g. minimum viewing distances, limits on the number of swimmers/boats, etc.). The findings also emphasise that economics should not be the only or primary metric used to measure conservation success; rather, the focus should be on assessing a more comprehensive range of social and ecological conservation outcomes of these activities. / Graduate / 2020-04-16
124

Abundance, Distribution, and Habitat Use of Sharks in Two Northeast Florida Estuaries

McCallister, Michael Philip 01 January 2012 (has links)
Sharks are considered top predators in many marine ecosystems, and can play an important role in structuring those communities. As a result, it is necessary to understand the factors that influence their abundance and distribution. This is particularly important as fishery managers develop fishery management plans for sharks that identify areas that serve as essential fish habitat (EFH). This includes nursery habitat where sharks are born and juveniles spend the early part of their life. However, our understanding of shark habitat use in the northeast Florida waters is limited. The goal of this thesis was to characterize the abundance and distribution of sharks in northeast Florida estuaries, and to examine the effect of abiotic and biotic factors affecting shark habitat use. A bottom longline survey conducted from 2009 – 2011 indicated that 11 shark species use the estuarine waters of northeast Florida during summer months. Atlantic sharpnose (Rhizoprionodon terraenovae), blacktip (Carcharhinus limbatus), bonnethead (Sphyrna tiburo), and sandbar sharks (Carcharhinus plumbeus) were the most abundant species and made up 87.1% of the total catch. Month, bottom water temperature, and depth were the most important factors determining the presence and abundance of these species. This study also examined the role of prey abundance in determining the abundance of Atlantic sharpnose sharks. The probability of catching an Atlantic sharpnose shark, and the abundance of Atlantic sharpnose sharks, were most influenced by site. Neither potential prey abundance nor preferred prey abundance were not significant factors effecting Atlantic sharpnose abundance. This may be a result of prey sampling not providing an accurate measure of the true availability of prey resources. Other factors, such as predation risk, may better explain habitat use patterns of Atlantic sharpnose sharks. Continued sampling will give a better understanding of the factors influencing shark habitat use in this area.
125

Presença da proteína Indoleamina 2, 3-dioxigenase (IDO) na interface materno-fetal de Prionace glauca (Linnaeus, 1758) / Presence of the protein Indoleamine 2,3- dioxigenase on the materno-fetal interface of Prionace glauca

Salmon, Thierry 09 September 2015 (has links)
O tubarão-azul (Prionace glauca) é uma espécie que apresenta desenvolvimento vivíparo placentário em que o saco vitelino se desenvolve ao longo da gestação tornando-se uma placenta que executa função matrotrófica. A Indoleamina 2,3-dioxigenase (IDO) é uma proteína encontrada em mamíferos nos quais participa, além de outras funções, da tolerância materno-fetal, sendo também encontrada em peixes ósseos. Assim, a proposta deste trabalho foi verificar a expressão da IDO na interface materno-fetal de Prionace glauca e descrever sua localização. Para tanto, material placentário/uterino e embriológico de três fases distintas da gestação (pré-placenta, meia gestação e fim da gestação) de fêmeas de P. glauca foram coletados e processados para a imuno-histoquímica. Os resultados mostraram a presença da IDO ao longo do desenvolvimento do saco vitelino/placenta, na ectoderme nas três fases e na endoderme apenas nas duas primeiras fases. No epitélio uterino observou-se a marcação da IDO nas duas últimas fases. Esses tecidos de interface seriam locais de maior contato entre a mãe e o concepto, fato que poderia levar à indução de uma resposta imunológica contra o concepto semi-alogenêico. A soma destes fatores poderia contribuir como um indício de uma possível atuação da IDO como mecanismo da tolerância materno-fetal na interface placentária de Chondrichtyes, como relatado em mamíferos eutérios / The blue shark (Prionace glauca) is a viviparous placentary species in which the yolk sac develops along pregnancy turning into a placenta with a matrotrofic role. The indoleamine 2 3-dioxygenase (IDO) is a protein usually described in mammals, which, among other functions, participates on the maternal-fetal tolerance process. Although it has also been reported in bony fish, no information is available regarding its function. Therefore, the purpose of this study was to investigate the expression of IDO in blue shark maternal-fetal interface and describe its distribution. Thus, placental / uterine and embryonic materials from three different stages (pre-placenta, middle and late gestation) of pregnant P. glauca females were processed for immunohistochemistry. The results showed IDO labelling during the yolk sac / placenta development in ectoderm along the three development phases and at endoderm only at phases I and II. In uterine epithelium, IDO was observed in the last two phases. These interface tissues are major contact areas between the mother ant the conceptus, that would induce an immunological response against the semialogeneic conceptus.The sum of these factors may contribute as an indication to the possible IDO role as a mechanism of maternal-fetal tolerance in Chondrichtyes placentary interface, as described in eutherian mammals
126

Ecologia do tubarão lombo preto Carcharhinus falciformis (Muller & Henle, 1839) na margem ocidental do oceano atlântico equatorial

LANA, Fernanda de Oliveira 13 February 2012 (has links)
Submitted by (edna.saturno@ufrpe.br) on 2017-02-13T12:40:28Z No. of bitstreams: 1 Fernanda de Oliveira Lana.pdf: 2191655 bytes, checksum: 1c0fe338043dce8d998d515ebec30b36 (MD5) / Made available in DSpace on 2017-02-13T12:40:28Z (GMT). No. of bitstreams: 1 Fernanda de Oliveira Lana.pdf: 2191655 bytes, checksum: 1c0fe338043dce8d998d515ebec30b36 (MD5) Previous issue date: 2012-02-13 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / The silky shark, Carcharhinus falciformis, is an abundant species in tropical and equatorial waters of the pelagic zone. The present work aimed at studying the ecology of the silky shark, including aspects of its reproduction, relative abundance, distribution, habitat use and migration on the Equatorial Atlantic Ocean. From November 1992 to December 2011, 153 specimens were examined, 72 males and 81 females, resulting in a sex ratio close to 1:1 (0.89:1.00). All specimens were caught by commercial tuna longline boats, in the area located between 08°N to 53°S latitude and 08°E to 48°W longitude. The results suggest a size at first maturity for females around 205- 210 cm and for males between 180- 200 cm TL. Females were found in 5 maturational stages: juvenile (n = 29/ 35.8% from 74 to 204 cm, TL), maturing (n = 10 / 12.3%, from 215 to 295 cm TL), pre- ovulatory (n = 14 / 17.3%, 177 to 280 cm TL), pregnant (n = 24 / 29.6%, 203 to 270 cm TL) and resting (n = 4 / 4.9%, from 223 to 285 cm TL). Males were classified into 4 stages: juvenile (n = 38/ 52.8% from 81 to 220 cm TL and clasper length - CL <12 cm), maturing (n = 16/ 22.2%, from 166 to 208 TL cm, 9.5 to 24.5 cm CL;), adult (n = 17/ 23.6%, from 141 to 272 cm TL, CL> 24.5 cm) and neonate (n = 1/ 1.4%, 82 cm TL, CL 4 cm). Catch and effort data from 16.016 sets made by Brazilian tuna longliners, from 2004 to 2011, were analyzed. The CPUE was calculated and the catch and effort data were grouped in squares of 5° x 5° latitude and longitude. Two silky sharks were tagged with satellite transmitters PSAT (Pop-up Satellite Archival Tag), in the vicinity of Archipelago of Saint Peter and Saint Paul – ASPSP, but from only one it was possible to recover the data. The preferred temperature range of the tagged animal was between 27 and 28°C with a preferred depth between 1 and 10m. / O tubarão lombo-preto, Carcharhinus falciformis, é uma espécie abundante na zona pelágica, com distribuição em águas tropicais e equatoriais de todos os oceanos do mundo. O presente trabalho teve por objetivo estudar a ecologia do tubarão lombo-preto, incluindo aspectos da sua reprodução, abundância relativa, distribuição, uso do habitat e padrões de migração, na margem ocidental do Oceano Atlântico Equatorial. No período de novembro de 1992 a dezembro de 2011, foram examinados 153 exemplares, 72 machos e 81 fêmeas, resultando uma proporção sexual próxima de 1:1 (0,89:1,00). Todos os espécimens foram capturados por barcos da frota comercial atuneira, que realizaram pescarias com espinhel pelágico, na área localizada entre as latitudes de 08°N e 53°S e longitudes de 08°E e 48°W. Os resultados obtidos sugerem um tamanho de primeira maturação sexual para as fêmeas em torno de 205- 210 cm, e para os machos entre 180- 200 cm de comprimento total (CT). As fêmeas se encontravam em 5 estágios maturacionais: juvenil (n= 29; 35,8%; 74 a 204 cm de CT), em maturação (n= 10; 12,3%; 220 a 295 cm CT), pré-ovulatória (n= 14; 17,3%; 177 a 280cm CT), grávida (n= 24; 29,6%; 203 a 270cm CT); e em repouso (n= 4; 4,9%; 223 a 285 cm CT). Os machos foram classificados em 4 estágios: juvenil (n= 38; 52,8%; 81 a 220 cm CT e Comprimento do Clásper CC < 12 cm), em maturação (n= 16; 22,2%; 166 a 208 cm CT, 9,5 a 24,5 cm CC), Adulto (n= 17; 23,6%; 141 a 272 cm CT; CC > 24,5 cm) e neonato (n= 1; 1,4%; 82 cm CT; 4 cm CC). Foram analisados dados de captura e esforço de pesca de 16.016 lançamentos com espinhel pelágico de deriva, realizados pela frota brasileira atuneira, de 2004 a 2011. A CPUE foi calculada e os dados de captura e esforço foram agrupados em quadrados de 5° x 5° de latitude e longitude. Dois tubarões lombo-preto foram marcados com transmissores via satélite do tipo PSAT (Pop-up Satellite Archival Tag), nas imediações do Arquipélago de São Pedro e São Paulo- ASPSP, mas apenas em um deles foi possível a recuperação dos dados. A faixa de temperatura preferencial do animal marcado se situou entre 27 e 28°C, com uma profundidade preferencial entre 1 e 10m.
127

Reproductive Biology of the Tiger Shark in the Western Atlantic Ocean

Shields, Chelsea 01 January 2018 (has links)
Although tiger sharks are an important apex predator in many ecosystems, little is known about their reproduction. The goal of this study was to determine the size-at-maturity and the reproductive seasonality of tiger sharks in the western Atlantic Ocean. This was achieved using a combination of ultrasonography and measurements of plasma hormone concentrations; in particular, testosterone for males and estradiol and progesterone for females. Steroid hormone concentrations were measured using chemiluminescent assays (CLIA). Maturity was also examined through histology of reproductive organs in females and clasper calcification in males. Females were found to mature between 270 and 310 cm total length and males were found to mature between 260 and 300 cm total length. Mating was determined to occur in October/November, based on the presence of mating wounds on females and increased concentrations of testosterone in males. Some females were shown to exhibit increased plasma estradiol concentrations also during October/November; however, we do not believe that ovulation takes place until May or June based on ultrasonography data. This suggests a period of sperm storage although histological examination of the oviducal gland was not able to confirm this. Ultrasonography data, showing increasing embryo size over the course of a year, and data on minimum size of tiger sharks caught in longline surveys suggested that parturition occurs between June and September with pups being born as small as 56 cm fork length. The findings from this study show that some tiger sharks reach reproductive maturity at sizes smaller than what has been previously suggested. Additionally, the possibility of tiger sharks storing sperm suggests that their reproductive cycle is a minimum of two years long and could be up to three years in duration. This information is important for management of the species in the future. Additionally, this study adds to the limited knowledge about reproduction of elasmobranchs and how patterns of reproductive steroids can correlate with different reproductive events.
128

“You Want To Capture Something that Will Make People Change”: Rhetorical Persuasion in The Cove, Whale Wars, and Sharkwater.

Stewart, Jessica January 2014 (has links)
Dolphins, whales, and sharks are some of the world’s most iconic animals. Yet, many people will only ever see these animals via the media. The media, then, hold significant power in creating, modifying, or reaffirming the imaginaries around various species which, in turn, influences how much concern is given to matters related to their welfare and conservation. Given the environmental and ecological concerns presently facing the ocean, protecting, conserving, and preserving the marine ecosystem is vital, and time is of the essence. Through the work of activists, three specific marine wildlife issues have received a lot of publicity across various forms of mainstream media: the killing of dolphins in Taiji, Japan for their meat; Antarctic whaling; and the practice of shark-finning. Three activist films, namely The Cove (2009), Whale Wars (2008-), and Sharkwater (2006), are centred on these issues, and filmmakers attempt to compel viewers to support the activists’ protectionist cause. In order for this goal to have a chance of coming to fruition, rhetorical arguments must be carefully crafted. Yet, the study of rhetoric in animal-focused activist films is still an understudied research area. This thesis contributes to this area of research by using the aforementioned films as case studies by applying Aristotle’s rhetorical proofs of ethos, pathos, and logos to analyse the rhetorical arguments. Ethos is demonstrable when the activists construct themselves as credible, moral heroes and the animals as possessors of positive traits worth protecting, and the hunters as immoral villains. The graphic imagery of animal death appeals to pathos to stir strong bodily and emotional responses such as sadness, and disgust in order to mobilize audience support for cause. Lastly, these films appeal to logos through the use of culturally authoritative discourses such as those of biology, western conventional medicine, and the legal system. This thesis essentially argues that these texts work rhetorically and discursively to persuade audiences to feel a connection with and sympathy towards the animals; to be supportive of the activists; and to prompt antipathy towards the hunters and industry spokespeople.
129

Estimating groundwater discharge in the oligohaline ecotone of the Everglades using temperature as a tracer and variable-density groundwater models

Spence, Victora 01 January 2011 (has links)
Recent research suggests that brackish, marine-derived groundwater up-wells in the oligohaline ecotone of the coastal Everglades, bringing with it phosphorus to an otherwise phosphorus-poor environment. The purpose of this study is to estimate the rates and timing of the groundwater discharge by using variable-density groundwater models constructed, calibrated, and validated with field measurements of hydraulic head and surface and subsurface temperature. Modeled groundwater discharge rates ranged from 5.4E-04 mm/day in August to -1.3E-03 mm/day in June for Shark Slough and 4.8E-01 mm/day in June to -1.4E-01 mm/day in January for Taylor Slough, where positive values imply groundwater discharge and negative values imply groundwater recharge. These results indicate that groundwater discharge rates during the period of study were low and perhaps a negligible source of marine-derived phosphorous in the oligohaline ecotone of Shark Slough but much higher and perhaps significant source of marine-derived phosphorous in the oligohaline ecotone of Taylor Slough.
130

A study of the interaction between the physical and ecological processes of three aquatic ecosystems

Bruce, Louise Christina January 2007 (has links)
Due to the complex nature of aquatic food webs, the interaction between abiotic and biotic factors that govern ecosystem dynamics is often elusive. Recent advancements in both the collection of reliable field data and the development of ecological models have enabled researchers to gain insights into these more complex interactions. In this study the relationship between physical and ecological processes has been explored by applying a process based coupled physical and ecological model (DYRESM-CAEDYM) to the data sets of three aquatic ecosystems. In the first, the role of zooplankton in the nutrient cycles of Lake Kinneret, Israel was quantified. The model was parameterized and calibrated using an extensive field data set. It was found that the excretion of dissolved nutrients by zooplankton accounted for up to 58% of phytoplankton demand and that this value varied seasonally in response to patterns of stratification and mixing. In the second ecosystem, Mono Lake, USA, results from model simulations were studied to determine the significance of the transport of nutrient rich hypolimnetic water via the benthic boundary layer (BBL) on lake productivity. Model results indicated that although on average the impact of BBL transport on Mono Lake ecology was not large, significant nutrient fluxes were simulated during periods when BBL transport was most active. The timing of these fluxes in the context of seasonal changes were found to be critical to specific aspects of food web dynamics. In the final application, the ecological gradients of the primary salt ponds of Shark Bay, Australia were studied with specific focus on the role of zooplankton as a determinant of ecosystem dynamics. Model results indicated that zooplankton grazing was responsible for reduced water column particulate organic matter and increased light available for the development of microbial mats. However, no direct 8 link between zooplankton grazing and observed changes in planktonic algal species composition or nutrient limitation across the salinity gradient of the ponds was found. Results from this study demonstrate the potential of a lake ecosystem model to extract useful process information to complement field data collection and address questions related to the relationship between physical and ecological processes in aquatic ecosystems.

Page generated in 0.0761 seconds