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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.
31

Bioinspired Interactions with Complex Granular and Aquatic Environments

January 2020 (has links)
abstract: August Krogh, a 20th century Nobel Prize winner in Physiology and Medicine, once stated, "for such a large number of problems there will be some animal of choice, or a few such animals, on which it can be most conveniently studied." What developed to be known as the Krogh Principle, has become the cornerstone of bioinspired robotics. This is the realization that solutions to various multifaceted engineering problems lie in nature. With the integration of biology, physics and engineering, the classical approach in solving engineering problems has transformed. Through such an integration, the presented research will address the following engineering solution: maneuverability on and through complex granular and aquatic environments. The basilisk lizard and the octopus are the key sources of inspiration for the anticipated solution. The basilisk lizard is a highly agile reptile with the ability to easily traverse on vast, alternating, unstructured, and complex terrains (i.e. sand, mud, water). This makes them a great medium for pursuing potential solutions for robotic locomotion on such terrains. The octopus, with a nearly soft, yet muscular hydrostat body and arms, is proficient in locomotion and its complex motor functions are vast. Their versatility, "infinite" degrees of freedom, and dexterity have made them an ideal candidate for inspiration in the fields such as soft robotics. Through conducting animal experiments on the basilisk lizard and octopus, insight can be obtained on the question: how does the animal interact with complex granular and aquatic environments so effectively? Following it through by conducting systematic robotic experiments, the capabilities and limitations of the animal can be understood. Integrating the hierarchical concepts observed and learnt through animal and robotic experiments, it can be used towards designing, modeling, and developing robotic systems that will assist humanity and society on a diversified set of applications: home service, health care, public safety, transportation, logistics, structural examinations, aquatic and extraterrestrial exploration, search-and-rescue, environmental monitoring, forestry, and agriculture, just to name a few. By learning and being inspired by nature, there exist the potential to go beyond nature for the greater good of society and humanity. / Dissertation/Thesis / Doctoral Dissertation Mechanical Engineering 2020
32

Self-Burrowing Mechanism and Robot Inspired by Razor Clams

January 2020 (has links)
abstract: The Atlantic razor clam burrows underground with effectiveness and efficiency by coordinating shape changings of its shell and foot. Inspired by the burrowing strategy of razor clams, this research is dedicated to developing a self-burrowing technology for active underground explorations by investigating the burrowing mechanism of razor clams from the perspective of soil mechanics. In this study, the razor clam was observed to burrow out of sands simply by extending and contracting its foot periodically. This upward burrowing gait is much simpler than its downward burrowing gait, which also involves opening/closing of the shell and dilation of the foot. The upward burrowing gait inspired the design of a self-burrowing-out soft robot, which drives itself out of sands naturally by extension and contraction through pneumatic inflation and deflation. A simplified analytical model was then proposed and explained the upward burrowing behavior of the robot and razor clams as the asymmetric nature of soil resistances applied on both ends due to the intrinsic stress gradient of sand deposits. To burrow downward, additional symmetry-breaking features are needed for the robot to increase the resistance in the upward burrowing direction and to decrease the resistance in the downward burrowing direction. A potential approach is by incorporating friction anisotropy, which was then experimentally demonstrated to affect the upward burrowing of the soft robot. The downward burrowing gait of razor clams provides another inspiration. By exploring the analogies between the downward burrowing gait and in-situ soil characterization methods, a clam-inspired shape-changing penetrator was designed and penetrated dry granular materials both numerically and experimentally. Results demonstrated that the shell opening not only contributes to forming a penetration anchor by compressing the surrounding particles, but also reduces the foot penetration resistance temporally by creating a stress arch above the foot; the shell closing facilitates the downward burrowing by reducing the friction resistance to the subsequent shell retraction. Findings from this research shed lights on the future design of a clam-inspired self-burrowing robot. / Dissertation/Thesis / Video for section A1 of APPENDIX A / Video for section A2 of APPENDIX A / Video for section A3 of APPENDIX A / Video for section B8 of APPENDIX B / Doctoral Dissertation Civil, Environmental and Sustainable Engineering 2020
33

Comparative Analysis of Muscle Architecture and Myosin Heavy Chain Content in the Forelimbs of Geomyid and Heteromyid Burrowing Rodents

Fain, Jordan 02 September 2021 (has links)
No description available.
34

Owners Versus Renters: Comparative Homing Behaviors in Primary and Tertiary Burrowing Crayfish

Kamran, Maryam 15 July 2016 (has links)
No description available.
35

Role of Dreissena as ecosystem engineers: Effects to native bioturbators and benthic community structure and function

DeVanna, Kristen M. January 2006 (has links)
No description available.
36

Evaluating the Effects of Cheatgrass on Western Burrowing Owls

Draughon, Kaylee R. 21 June 2024 (has links) (PDF)
There has been a global decline of specialist species observed in recent decades due to the impacts of climate change, invasive species, and habitat loss. Habitat loss and degradation may lead to a mismatch between habitat attractiveness and actual quality, otherwise known as an ecological trap. Ecological traps occur when an organism is constrained by its evolutionary past to select for cues that no longer accurately predict habitat quality. Specialist species are more susceptible to ecological traps due to greater reliance on and fidelity to historic sites and resources. The burrowing owl (Athene cunicularia), a specialist bird species adapted to open ecosystems, has declined throughout its extent. Anthropogenic activity has drastically and rapidly altered burrowing owl native habitat, exposing their habitat to disturbances such as cheatgrass (Bromus tectorum) invasion. The presence of cheatgrass is known to impact the biota of a region and understanding those impacts is becoming increasingly important. The purpose of this study was to quantify the impact of cheatgrass on burrowing owl populations. By assessing how cheatgrass influences the resource selection, nesting success, and food habits of burrowing owls, we provided information that can be utilized to make more informed decisions on how to conserve burrowing owls and their critical nesting habitat. In addition, this information can provide insight into the risk of ecological traps occurring to all specialist species experiencing degradation of their native habitat.
37

O espaço subterrâneo do rato-de-espinho Clyomys bishopi: caracterização e previsões possí­veis sobre sua biologia comportamental / The subterranean space of spiny rat Clyomys bishopi: characterization and predictions about its behavioral biology

Luchesi, Lilian Cristina 01 April 2019 (has links)
ambiente subterrâneo oferece rotas de deslocamento entre pontos de forrageamento ou local de estoque de alimentos e abrigo contra predadores e frio ou calor intensos. Dentre os roedores, cerca de 250 espécies usam o espaço subterrâneo (11%). Algumas dessas espécies são \"subterrâneas estritas\", mas a maioria são \"fossoriais\" em diferentes graus de dependência do subterrâneo, como o Clyomys bishopi que forrageia sobre a terra. O objetivo deste trabalho foi caracterizar o sistema subterrâneo dessa espécie endêmica do cerrado paulista, e correlacionar com aspectos distais e proximais do comportamento de escavação. No primeiro capítulo, são descritos os sistemas subterrâneos e verificadas suas relações com variáveis ambientais. No segundo, o uso do espaço pela espécie é investigado a partir da dinâmica de abertura das bocas de tocas de sistemas ao longo de dois anos. No terceiro capítulo, a temperatura interna dos sistemas é caracterizada e investigada quanto à sua relação com variáveis ambientais. Finalmente o último capítulo apresenta uma revisão sistemática sobre o uso de sistemas subterrâneos em Rodentia. Os sistemas subterrâneos de C. bishopi são complexos, com diversos túneis, bocas e câmaras de estocagem de sementes e com material de ninho. Os sistemas são maiores e mais profundos na estação seca do que na chuvosa. A espécie abre e fecha as bocas de seus sistemas ao longo do ano, e o maior número de abertura de bocas foi encontrado na estação seca em paisagem aberta, apoiando a hipótese de que os sistemas subterrâneos para a espécie funcionam principalmente como rotas de deslocamento entre áreas de forrageamento, protegidos de predadores. A temperatura apresenta um ciclo circadiano com acrofase após o pôr do sol sem distinção entre as estações climáticas, têm relações com a paisagem em que estão inseridas, sendo menores nas paisagens fechadas e mais elevadas na chuva, com temperatura mais elevada dentro da toca durante a noite e início da manhã. Os hábitos subterrâneos carregam sinais filogenéticos e tem relação com hábitos sociais, interações com o ambiente e a disponibilidade de alimento nos dois sentidos, seja no ganho ou na perda da socialidade. A manutenção da vida social numa espécie e a complexidade dos sistemas relacionam-se também com a maior compactação do solo. A hipótese das relações evolutivas entre a formação de colônias de sistemas subterrâneos, com seus usos e a vida social pode ser testada em trabalhos futuros / The subterranean environment provides displacement routes between foraging points or food storage locations and shelter from predators and intense heat or cold. Among rodents, about 250 species use underground space (11%). Some of these species are strictly subterranean, but most of them are \"fossorial\" in varying degrees of subterranean dependence, such as the Clyomys bishopi that forages above ground. The aim of this study was to characterize the burrow system of this species (that is endemic to cerrado of São Paulo) and to correlate with distal and proximal aspects of the burrowing behavior. In the first chapter, the burrow systems are described and their relationships with environmental variables are verified. In the second, the use of space by the species is investigated from the dynamics of opening and closing burrow systems entrances over two years. In the third chapter, the internal burrow\'s temperature is characterized and it is investigated in relation to the environmental variables. Finally, the last chapter presents a systematic review about the use of burrow systems in Rodentia. Burrow systems of C. bishopi are complex, with several tunnels, entrances and chambers of food storage and nest material. The systems are larger and deeper in the dry season than in the rainy one. The species opens and closes the entrances of its systems throughout the year, and the largest number of entrance openings was found in the dry season that are in open landscape, supporting the hypothesis that this species uses the burrow systems mainly as displacement routes between foraging areas, protected from predators. Temperature exhibits a circadian rhythm with acrophase after sunset without distinction between climatic seasons. This rhythm has relations with the landscape in which they are inserted: smaller in the closed landscapes and more elevated in the rain with higher temperature inside the burrow during night and early in the morning. Subterranean lifestyle carries phylogenetic signals and is related to social habits with interactions between the aridity and the availability of food and sociality on both directions: gain or loss of sociality. Also there are relations soil hardness, burrow\'s complexity and the maintenance of sociality among species. The hypothesis of the evolutionary relationships between the formation of burrow systems colonies with their uses and sociality can be tested in future studies
38

Uso de hábitat por tatus em área de floresta de restinga do sul do Brasil

Nitta, Carlos Hiroshi 28 February 2008 (has links)
Submitted by Maicon Juliano Schmidt (maicons) on 2015-03-24T19:11:22Z No. of bitstreams: 1 Carlos Hiroshi Nitta.pdf: 684742 bytes, checksum: 0857f27947f3270ae0fa6aba1e59c2da (MD5) / Made available in DSpace on 2015-03-24T19:11:22Z (GMT). No. of bitstreams: 1 Carlos Hiroshi Nitta.pdf: 684742 bytes, checksum: 0857f27947f3270ae0fa6aba1e59c2da (MD5) Previous issue date: 2008-01-31 / Nenhuma / Os tatus (Cingulata: Dasypodidae), apesar da diversidade de espécies, 21 espécies, e ampla distribuição, da Argentina até a metade sul dos EUA, passando pela América Central, as informações sobre a utilização dos ambientes por estes animais é escassa. A escavação e utilização de buracos no solo é uma característica ecológica relevante para o grupo, podendo estas estruturas serem consideradas indicadores conspícuos da presença desses animais. No presente estudo investiguei a densidade, direção, morfometria e microhabitat das tocas, em diferentes tipos de formação vegetal. O trabalho foi desenvolvido durante 13 meses (Out/06 a Nov/07) no Parque Estadual de Itapuã, na Grande Porto Alegre, RS, Brasil. O tatu-galinha (Dasypus novemcinctus) parece ser a espécie mais abundante neste local, onde ainda ocorre ao menos uma outra espécie, tatu-de-rabo-mole-grande (Cabassous tatouay). As características físicas e ambientais de 72 tocas, no campo (n = 31), mata (n = 22) e Restinga (n = 19), encontradas foram analisadas. A densidade de tocas não variou significativamente entre estes ambientes. Embora o tatu-galinha seja apontado como uma espécie de áreas florestadas no presente estudo, as áreas abertas foram utilizadas com a mesma intensidade que mata e restinga. Dentre as variáveis ambientais o número de árvores e porcentagem de cobertura de solo por arbustos tiveram influência no número de tocas encontradas em mata. A direção das tocas foram predominantemente sul nas áreas de floresta (mata e restinga) e significativamente diferentes das áreas de campo (campoXmata p = 0,002; campoXrestinga p = 0,001). Sugerindo que esta espécie possa mudar o comportamento e aumentar o nicho na ausência ou relaxamento de predadores e competidores. / Armadillos ( Cingulata : Dasypodidae ), despite the diversity of species , 21 species , and wide distribution , from Argentina to the southern half of the United States through Central America, information on the use of animals in these environments is scarce. The excavation and using holes in the ground is an important ecological nature of the group, these structures may be considered conspicuous indicators of the presence of these animals. In the present study I have investigated the density, direction, morphometric and microhabitat of the burrows in different types of plant formation. The study was conducted during 13 months (Oct/06 to Nov/07) in Itapuã State Park, in Porto Alegre , RS , Brazil . The nine-banded armadillo (Dasypus novemcinctus) seems to be the most abundant species at this site, which is still at least one other species, the greater naked-tailed armadillo (Cabassous tatouay). The physical and environmental characteristics of 72 holes, fields (n = 31), forest (n = 22) and Restinga (n = 19), found were analyzed. The density of burrows did not vary significantly between these environments. Although the nine-banded is touted as a kind of wooded areas in the present study, the open areas were used with the same intensity that forest and dunes. Among the environmental variables the number of trees and percentage of ground cover shrubs influenced the number of burrows found in the woods. The direction of the burrows were predominantly southern areas of forest (forest and Restinga) and significantly different from field areas (fieldXforest p = 0.002; fieldXrestinga p = 0.001). Suggesting that this species can change behavior and increase the niche or relaxation in the absence of predators and competitors.
39

A Multi-scale Evaluation of Pygmy Rabbit Space Use in a Managed Landscape

Wilson, Tammy L. 01 May 2010 (has links)
Habitat selection has long been viewed as a multi-scale process. Observed species responses to resource gradients are influenced by variation at the scale of the individual, population, metapopulation, and geographic range. Understanding how species interact with habitat at multiple levels presents a complete picture of an organism and is necessary for conservation of endangered species. The main goal of this dissertation is to evaluate distribution, relative abundance, and habitat selection of a rare species, the pygmy rabbit Brachylagus idahoensis, at multiple scales in order to improve management and conservation for this species. At the broadest scale, pygmy rabbit occurrence and relative abundance were modeled in the Duck Creek allotment of northern Utah using a hierarchical spatial model. Pygmy rabbits are not easily observable, and the model used two levels of indirect detection to make statistically rigorous spatial predictions. We found that the model predicted the general pattern of rabbit occurrence and abundance within the study area, and that there was spatial heterogeneity in the probability of pygmy rabbit occurrence within a study domain that was known to be occupied. The resulting model framework could be used to develop a long-term monitoring program for pygmy rabbits and other species for which hierarchically nested levels of indirect observation are collected. The mid-scale analysis evaluated pygmy rabbit home range placement and movement with respect to sagebrush removal treatments using null models based on an optimal central place foraging behavior. While placement of home-range centers did not appear to be affected by the treatments, within-home range movements were farther from treatments than expected by the null models for two rabbits (of eight), and rabbits that approached treatment edges were less likely to enter treatments than expected by chance. Rabbits are not extirpated from sites that have been treated, but the observed reluctance to enter treated patches calls for caution when conducting sagebrush removal treatments near occupied pygmy rabbit burrows. At the finest level of resolution, the spatial ecology of pygmy rabbit use of burrows was evaluated. Both the placement of burrows in general and pygmy rabbit use of burrows were clustered. While the habitat gradients experienced by each of the rabbits evaluated affected the modeled habitat selection responses, some generalities were observed. Selection of high cover suggests that pygmy rabbit use of burrows may be linked to predator avoidance behavior. Additionally, pygmy rabbit use of clustered burrows affects management actions including: habitat modeling, monitoring, and species introduction. Explicit attention to resource distribution will improve efforts to predict species responses to management actions.
40

Terrestrial habitat requirements of a suite of anuran species inhabiting a semi-arid region of South East Queensland

Chambers, Joanne January 2008 (has links)
Hypothesised causes of the observed world-wide decline of amphibian populations are varied and in some cases contentious. Insufficient information relating to the autecology of many amphibian species can cause erroneous speculations regarding critical habitat requirements and hence management programs designed to enhance population viability are often unsuccessful. Most amphibians display a bi-phasic life history that involves occupation of an aquatic breeding habitat and terrestrial habitats that are used for foraging, and shelter from predation and environmental stress. However, the focus of most amphibian research is centred on the breeding habitat, with limited research being conducted into the terrestrial habitat requirements of most amphibian species. Barakula State Forest is a large continuous area of open woodland situated in the semi-arid region of Queensland. The forest supports 21 species of endemic anurans, many of which use ephemeral waterbodies for breeding. This area is, therefore, an ideal location to test the relative importance of terrestrial habitat on the distribution of a suite of frogs that display different morphological and physiological characteristics. On the landscape scale, the attributes of the terrestrial environment at three survey areas within Barakula were similar. However, at the patch scale, ground truthing showed there were considerable variations in vegetation and ground cover attributes within and between each survey site. Measured properties of the soil also tended to vary within and between sites. Soil texture ranged from sandy to heavy clay, soil pH ranged from 3.9 to 6.4 and soil moisture varied considerably. Agar models, used for testing evaporative moisture loss at different microhabitats, retained significantly higher levels of moisture when positioned in the buried microhabitat during summer, but in winter, models that were placed under leaf litter retained higher levels of moisture. Variations in levels of moisture loss at the five different microhabitats were evident within and between the survey sites. Despite a prolonged drought, 1844 native frogs representing 17 species were pitfall trapped. Members from the family Myobatrachidae comprised 94% of these captures, and burrowing species accounted for 75% of total captures. Species were not randomly distributed within or between the survey sites. Vegetation attributes and soil properties played a significant role in influencing the catch rates and traplines that supported similar vegetation and soil attributes also tended to catch similar species. Capture rates of six of the seven burrowing species were significantly influenced by soil properties. When given a choice of four different microhabitats created in enclosures, individuals from five species showed varying responses to habitat choice during night time activity. During daylight all species tended to avoid bare areas and burrowing species tended to burrow under some form of cover. Pseudophryne bibronii metamorphs showed a significant avoidance to soils with high pH. The number of Limnodynastes ornatus metamorphs was significantly and positively correlated with moisture levels surrounding a breeding area. Limnodynastes ornatus metamorphs tended to avoid areas that did not support some form of cover. Embryos from the terrestrial egg laying P. bibronii translocated to sites with varying levels of soil pH, suffered increased mortality where the soil pH was &gt4.8. In the laboratory, embryonic survival was not significantly different between the four pH treatments. There was a significant influence of fungal infection on survival rates and ranked fungal infection was significantly different between the four pH treatments. The terrestrial environment at the three survey sites has provided sufficient protection from environmental elements to allow a large diversity of anurans to persist for long periods without access to permanent water. Management must consider the importance of the non-breeding habitat when defining buffer zones, restoration programs and conservation strategies to ensure that the complete set of ecological requirements for frog species are provided.

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