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1
Ge, Liehui. "Synthetic Gecko Adhesives and Adhesion in Geckos." University of Akron / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=akron1294161826.
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Lopez, Stephanie M. "Effects of Digital Hyperextension on Self-Cleaning in the Tokay Gecko (Gekko gecko)." Akron, OH : University of Akron, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=akron1248642491.
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Thesis (M.S.)--University of Akron, Dept. of Biology, 2009."August, 2009." Title from electronic thesis title page (viewed 10/14/2009) Advisor, Peter Niewiarowski; Co-Advisors, Todd Blackledge, Ali Dhinojwala; Department Chair, Monte Turner; Dean of the College, Chand Midha; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.
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Snyder, Joshua P. "The autecology of Rhacodactylus auriculatus a natural history study of gargoyle geckos /." Click here for download, 2007. http://proquest.umi.com/pqdweb?did=1331400641&sid=1&Fmt=2&clientId=3260&RQT=309&VName=PQD.
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Cole, Nicholas Carl. "The ecological impact of the invasive house gecko Hemidactylus frenatus upon endemic Mauritian geckos." Thesis, University of Bristol, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.419134.
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Moyer, Robert Walter. "Comparative morphological and biochemical study of the pineal complex in geckos /." Title page, abstract and contents only, 1998. http://web4.library.adelaide.edu.au/theses/09PH/09phm938.pdf.
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Geneva, Anthony Joseph. "A phylogeographic analysis of Bavayia cf. crassicollis." Click here for download, 2007. http://proquest.umi.com/pqdweb?did=1428838771&sid=1&Fmt=2&clientId=3260&RQT=309&VName=PQD.
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Holmes, Scott. "Analysis of tooth replacement in adult leopard geckos." Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/44626.
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Though most dentate vertebrates replace their teeth at least once in the course of their lives, the process of tooth replacement is poorly understood. This is mainly because the major tooth development model is the mouse which only has one generation of teeth. Our previous work suggested that tooth renewal in geckos might involve dental epithelial stem cells and that these putative stem cells become transit- amplifying cells when exposed to canonical WNTs. Here we further investigate this idea using adult leopard geckos (Eublepharis macularius). To further previous findings from our lab that the dental apparatus is a WNT responsive tissue we perturbed the WNT pathway by agonist and antagonist organ cultures of oral tissue explants. BIO stimulated proliferation at an intermediate concentration of 20 μM but not at higher or lower concentrations. This suggests that in vivo, cells are responding to gradients of WNT activity. We also looked at associated BMP and FGF pathways via in situ histology and organ culture manipulation respectively and found alternating patterns of gene expression. We then mapped areas of high canonical WNT signaling and found that nuclear staining for phospho beta catenin was principally found in the outer enamel epithelium and successional lamina. We moved to an in vivo strategy to allow for better tissue survival. Palatal injections of LiCl or the control reagent NaCl were delivered to the base of the maxillary teeth. We found that LiCl increased proliferation in the successional lamina and cervical loops, areas that normally have higher proliferation. We conclude that certain regions of the dental epithelium are sensitive to change in canonical WNT signaling and that this signaling is potentially kept to a localized region via BMP inhibition of the WNT pathway. Regions of the dental lamina that contain putative stem cells may require signals in addition to WNTs to stimulate the formation of transit amplifying cells. Future work will further elucidate the many signaling cascades required for tooth succession to occur.
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Buckland, Jack Dany Steeves. "Status, ecology and conservation of endemic geckos in Mauritius." Thesis, University of Bristol, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.653090.
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In the past 400 years, there has been a drastic decline in the number of endemic species on mainland Mauritius, with the island losing 69% of its original reptile community. Of 17 endemic species, only five mostly Phelsuma species survived the human mediated disturbances on mainland Mauritius. These remaining arboreal endemic geckos still play important ecological roles in the Mauritian ecosystem. However, habitat fragmentation and introduction of invasive species have increased the threats to these endemic geckos. The recent invasion of the bigger Phelsuma grandis (giant Madagascar day gecko) has increased the threats posed to the existence of endemic geckos, while habitat loss and fragmentation is also playing a major role in gecko decline, particularly for Phelsuma guimbeaui (lowland forest day gecko). In this thesis, I studied the ecological effects of P. grandis on endemic geckos at a landscape and local scale using species .distribution and binomial mixture models. I also designed markers from microsatellite and mitochondrial DNA to research the population. genetics of P. guimbeaui in response to habitat fragmentation. Finally, I explored habitat selection of P. guimbeaui to find suita~le sites for potential translocations. First, I showed that P. grandis shared many characteristics of an invasive species and could persist in a relatively large range of environmental conditions. The results highlight that P. grandis and endemic gecko distributions can overlap. Where P .. grandis has invaded areas occupied by endemic geckos, the abundance of the Mauritian species has declined by an average of 89%. This study provides strong evidence that P. grandis and endemic geckos are unlikely to coexist in sympatry. Second, I designed arid amplified 44 markers from an enriched-microsatellite genomic library. They were tested on ten subpopulations and 20 were selected to examine the population genetics of the fragmented population of P. guimbeaui. Here, the microsatellite results suggested that most subpopulations were genetically different, with low effective population sizes and no migrations, while simulations showed that the different subpopulations were at high risks of losing genetic diversity and extinction. Mitochondrial DNA showed that the fragmented subpopulations used to be part of a panmictic population. Using the findings of this genetic study, 12 subpopulations were identified as viable and 18 subpopulations were at high risk. Third, I showed that P. guimbeaui males had a larger home range than females and males overlap more with females than males and geckos selected habitats with higher plant diversity, with trees that had taller and larger trunks and a higher cavity density. Adult geckos selected different habitat features compared to sub-adults and juveniles. The findings of this research were synthesised into a review to formulate the conservation assessment of the endemic geckos on mainland Mauritius.
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DAME, ELIZABETH. "BEHAVIORAL MECHANISMS OF INVASION AND DISPLACEMENT IN PACIFIC ISLAND GECKOS." University of Cincinnati / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1100810530.
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Dame, Elizabeth. "Behavioral mechnaisms of invasion and displacement in Pacific Island Geckos." Cincinnati, Ohio : University of Cincinnati, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=ucin1100810530.
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Benardino, Mariana Sofia Nunes. "Parasitas gastrointestinais de uma colecção privada de geckos-leopardo (Eublepharis macularius) e de répteis tidos como animais de estimação no Norte de Portugal." Master's thesis, Universidade de Lisboa. Faculdade de Medicina Veterinária, 2014. http://hdl.handle.net/10400.5/7616.
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Dissertação de Mestrado Integrado em Medicina VeterináriaDurante as últimas décadas, os répteis têm aumentado a sua popularidade como animais de estimação por todo o mundo, reflectindo-se este fenómeno num aumento do número de espécies disponíveis nas lojas de animais, bem como no número crescente de criadores destes animais por hobby ou com objectivos comerciais. Neste contexto, um rastreio de parasitas gastrointestinais foi efectuado a uma colecção de geckos-leopardos e répteis tidos como animais de estimação. As amostras recolhidas foram analisadas utilizando métodos coprológicos de flutuação, sedimentação, Mcmaster e esfregaço fecal. Relativamente à colecção privada de geckos-leopardo, foram analisadas um total de 49 amostras fecais para a presença de parasitas gastrointestinais. A prevalência de amostras positivas da população foi estimada entre 61,1 e 85,9%. Em todas as amostras positivas foram detectados ovos de vários géneros da superfamília Oxyuroidea (Pharyngodon sp., Ozolaimus sp. e um género não identificado), sendo que em aproximadamente 22,4% das amostras foi detectada também a presença do protozoário Nyctotherus sp. A eficácia do método da fita-cola para pesquisa de oxiurídeos foi testada em 20 animais, tendo sido determinada uma sensibilidade entre 4,9 – 49,3% e uma especificidade entre 25,5 – 100% face ao esfregaço fecal usado como gold standard. No âmbito de um rastreio parasitológico gastrointestinal realizado a répteis tidos como animais de estimação no norte de Portugal foram analisados um total de 28 amostras (correspondentes a 16 quelónios, 4 sáurios e 8 ofídios), tendo sido realizado também um pequeno questionário aos donos com o objectivo de apurar a origem dos animais e condições gerais de maneio. No total das amostras analisadas, foram encontradas formas parasitárias em 16 amostras (cerca de 57,1%). Quatro grupos de endoparasitas (nemátodes oxiurídeos (N=6), Nyctotherus sp. (N=5), amebas (N=4) e flagelados (N=3) de géneros não identificadas) foram detectados em 13 (81,3%) dos 16 quelónios participantes. Nos 4 sáurios, 2 grupos de endoparasitas (nemátodes oxiurídeos (N=3) e Nyctotherus sp. (N=1)) foram encontrados em 3 animais. Nas amostras dos 8 ofídios participantes não foram detectadas quaisquer formas parasitárias nas técnicas coprológicas realizadas. Sendo este o primeiro estudo parasitológico realizado em répteis de estimação em Portugal, os resultados obtidos evidenciam a importância do parasitismo em répteis em cativeiro e a necessidade de estudos futuros mais aprofundados sobre a fauna parasitológica destes animais e seu possível impacto na Saúde Pública e Animal.
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Tang, Minmin, and 汤敏敏. "Investigation of reversible adhesion mechanism in gecko's foot hair." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B45529280.
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Todd, Amanda Claire. "Mating strategies and sperm competition in New Zealand geckos (Family Gekkonidae)." Thesis, University of Canterbury. Zoology, 2003. http://hdl.handle.net/10092/1421.
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Most species of reptile studied to date have polygynandrous mating systems and possess specialised sperm storage regions. Consequently, there is a high potential for sperm competition in this group. Using comparative analyses, I examined the level of sperm competition in New Zealand geckos and how this has influenced the evolution of their reproductive morphology. Across lizards and snakes, there was more than a 40-fold variation in relative testis size. New Zealand geckos fell in the middle of this range and lacked sexual dimorphism in head size, suggesting that most species have polygynandrous mating systems. I confirmed this for one species, Hoplodactylus maculatus, which is gregarious, lacks territoriality and has a courtship pattern that suggests a high level of promiscuity for both sexes. I found that hemipenis size in New Zealand geckos was positively correlated with relative testis size, suggesting that sperm competition has resulted in the evolution of larger intromittent organs. However, the surface features of the hemipenis were relatively conservative across species. Although there was no relationship between sperm length or putative sperm storage site (SST) morphology and relative testis size, species with fewer SSTs, and thus more intense sperm competition, had longer sperm. H. maculatus males produced two types of sperm which differed not only in length but also in fertilising capacity, the short morph lacking DNA. This is the first known example of such sperm polymorphism in a vertebrate and may have evolved in response to sperm competition, the non-fertilising morph potentially helping to block the sperm of rival males or filling sperm storage sites. The motility of these short sperm was positively correlated with temperature; however, at higher temperatures motility declined with time, suggesting a trade-off between motility and longevity. Such temperature influences on male reproductive physiology have important implications for males of ectothermic species under sperm competition.
14
Huber, Gerrit. "Nanoscale adhesion of individual gecko spatulae explored by atomic force microscopy." [S.l. : s.n.], 2006. http://nbn-resolving.de/urn:nbn:de:bsz:93-opus-25315.
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Short, Kristen. "Population genetic structure and species displacement during range expansion of invasive geckos." University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1289840091.
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Bshaena, Ismail Mustafa [Verfasser], and Ulrich [Akademischer Betreuer] Joger. "Phylogenetics and systematics of North-African Geckos Tarentola / Ismail Mustafa Bshaena ; Betreuer: Ulrich Joger." Braunschweig : Technische Universität Braunschweig, 2011. http://d-nb.info/1175825603/34.
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Freeman, A. B. "An ecological study of the lizard fauna of Kaitorete Spit, Canterbury." Master's thesis, Lincoln University. Bio-Protection and Ecology Division, 1994. http://theses.lincoln.ac.nz/public/adt-NZLIU20080205.115012/.
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Baited pitfall traps were used to sample the lizard fauna at Birdlings Flat on Kaitorete Spit, Canterbury. Four species had been recorded previously from this area; Leiolopisma maccanni Patterson and Daugherty, Leiolopisma nigriplantare polychroma Patterson and Daugherty, Leiolopisma lineoocellatum (Dumeril and Dumeril) and Hoplodactylus maculatus (Gray). Three of these species (L. maccanni, L. n. polychroma and H. maculatus) were captured during the course of the study. The aim of this present study was to examine the nature of the ecological relationship among these three species at Birdlings Flat. Capture data indicated that L. maccanni was almost entirely confined to the dunelands while L. n. polychroma was associated exclusively with shrublands on old dune ridges behind the sand dunes. H. maculatus' distribution encompassed both of these major habitats. Separation on the basis of habitat was thought to be the most important niche variable for these two diurnal skinks. There was some temporal separation in activity of these two species, with L. maccanni active earlier in the day than L. n. polychroma. However, there was a high degree of overlap in the activity periods of these two species. Temporal differentiation between the nocturnal gecko H. maculatus and the two diurnal skinks is thought to be an important means by which these species coexist. The most common prey items consumed by all three species were Diptera, Araneae, C. propinqua seeds, Hemiptera, unidentified arthropod eggs, Coleoptera and Hymenoptera. Dietary differences between the two skink species were apparent although these differences appeared to be related to the preferred habitats of the respective species. Density estimates for L. maccanni varied between 1050/ha and 1850/ha while L. n. polychroma density varied between 200/ha and 400/ha. The density of H. maculatus was not calculated but appeared to be intermediate to the density of the two skink species. The apparent disappearance of L. lineoocellatum from an area where they were once relatively common is cause for concern. There is no obvious reason for this decline although it may be related to the combined impacts of predation, collection and habitat disturbance.
18
Garcia, Porta Joan. "Evolution and diversification of the geckos of the Arabian Peninsula and Socotra Archipelago, compared to other mainland-island systems." Doctoral thesis, Universitat de Barcelona, 2014. http://hdl.handle.net/10803/284436.
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A major challenge in evolutionary biology is understanding the main drivers that underlie morphological and species diversity. Ecological opportunity—access to new or previously inaccessible niches—has been identified as one of the most important drivers of both phenotypic and species diversification. This is because the exploitation of new ecological niches is often accompanied by phenotypic differentiation among closely related taxa. This can in turn facilitate species diversification if phenotypic differentiation is associated with the appearance of reproductive isolation. The main goal of this thesis is to explore the extent in which a major source of ecological opportunity—the colonization of islands—have driven evolutionary diversification in different taxonomic and geographic contexts, specifically in the geckos of Arabia and the Socotra Archipelago and the Australasian diplodactyloid geckos. Island colonization is thought to provide a context of many available resources with few competitors and predators. This allows to colonizing groups the possibility to experience an “ecological release” and use a wider array of niches compared to their continental close-relatives. In such a situation, we expect an expansion of the morphospace in island groups typically associated with high rates of phenotypic and species diversification. We have found compelling evidence for this in both of the two mainland-island systems studied. The Australasian diplodactyloid geckos clearly expanded the range of phenotypic variation existing in the continent, producing the biggest and the smallest species in the radiation and were associated to accelerated rates of body size diversification compared to their closest relatives in the continent. Likewise, in the Hemidactylus geckos from Arabia-Socotra, island species were also associated to accelerated rates of phenotypic diversification and, as in the Australasian system, produced the most extreme sizes in the radiation. In this last mainland-island system, aside of reaching the maximum and the minimum sizes, the body size disparities in continental species assemblages were always significantly greater than the disparities computed by continental species assemblages. Nonetheless, when we compare Hemidactylus to other groups diversifying in the same islands, it appears that not all groups equally tend to diversify in body size. In fact, the comparison of the stages of diversification between the three gecko genera occurring in the Archipelago of Socotra revealed that not a single path of intra-island diversification was shared by all genera. Hemidactylus and Haemodracon greatly diversified in body size. However, in Pristurus diversification was strongly mediated by climatic shifts with size diversification being displaced to a subtle role. This is an important result as suggests that not all groups respond in the same way to similar amounts of ecological opportunity and that group-dependent (intrinsic) components can potentially play a role at defining the different stages of diversification. Aside of these examples of island diversification, in this thesis I also exposed remarkable examples of “island-like” patterns of diversification occurring in the continent. This was the case for the Australasian Pygopodidae, which attained rates of phenotypic diversification (possibly species diversification too) comparable to those found in island groups and was mostly mediated by the acquisition of a remarkable key innovation: a “snake-like” phenotype. Another remarkable example of continental diversification revealed in this thesis is a complex of highly divergent species existing within the subspecies Pristurus rupestris rupestris. This diversification took place in truly “island-like” setting, the Hajar Mountains in southeastern Arabia, formed by three main isolated blocks or “sky islands”. However, in this case diversification failed to take place within each of the “islands” and mostly was driven through intermittent pulses of dispersal and isolation taking place between two of the two main mountain blocks. Examples like this provide an example of how continental groups in some contexts, as the ones offered by mountain ranges, can fuel substantial amounts of diversification. In this case one of the greatest vertebrate diversification in Arabia.Uno de los retos más importantes en biología evolutiva es entender las causas principales de la diversidad de fenotipos y de especies. La oportunidad ecológica (o el acceso a recursos nuevos y previamente inaccesibles) se considera como uno de los factores más importantes en la generación de nuevas especies y fenotipos. El objetivo principal de esta tesis es estudiar el papel generador de especies y fenotipos de uno de los grandes tipos de oportunidad ecológica, la colonización de islas. Para ello, se han usado dos sistemas continente-isla como modelo: los gecos de Arabia y el Archipiélago de Socotra y los gecos diplodactiloideos australasiáticos. Dado que las islas proporcionan ambientes con pocos competidores y depredadores, esto permite a los grupos insulares experimentar una gran expansión de nicho que puede estar asociada a una expansión del morfoespacio mediada por tasas elevadas de diversificación fenotípica y de especies. Los resultados de esta tesis respaldan totalmente esta hipótesis. Tanto en los gecos australasiáticos como en los gecos de Arabia y Socotra, la colonización de islas vino acompañada con aumentos sustanciales de disparidad fenotípica asociados con incrementos en las tasas de diversificación de tamaños del cuerpo y de especies. Aunque esto subraya la gran capacidad que tienen los entornos insulares en promover diversificación, diferentes grupos diversificando en las mismas islas no necesariamente siguen caminos evolutivos equivalentes. En el archipiélago de Socotra, la diversificación intra-isla en los géneros Hemidactylus y Haemodracon estuvo acompañada de grandes cambios del tamaño del cuerpo, que sólo posteriormente derivaron en cambios macroecológicos. Por el contrario, en el género Pristurus, la diversificación intra-isla fue principalmente mediada por cambios macroecológicos, siendo la diversificación del tamaño del cuerpo casi inapreciable. Esto demuestra que grupos cercanos diversificando en las mismas islas, pueden presentar patrones de diversificación completamente dispares. Al margen de las diversificaciones intra-isla expuestas, los resultados de esta tesis también han expuesto importantes patrones de diversificación también en el continente. Uno de ellos es el encontrado en los gecos pigopódidos australasiáticos, que después de adquirir una innovación clave (un fenotipo en forma de serpiente), entraron en dinámicas de diversificación comparables a los grupos insulares. Otro ejemplo destacado trabajado en esta tesis la diversidad encontrada dentro de la subespecie de geco Pristurus rupestris rupestris. Esta subespecie, en realidad, está formada por 14 especies altamente divergentes que diversificaron en las montañas del noroeste de Arábico, constituyendo uno de los casos más extremos de diversificación en vertebrados en Arabia.
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Hays, Brenton J., Joseph R. Bidwell, and Drew E. Dittmer. "An Assessment of Thermal Preference of Two Species of Knob-tailed Geckos, Nephrurus levis and N. laevissimus, at Uluru Kata-Tjuta National Park." Digital Commons @ East Tennessee State University, 2019. https://dc.etsu.edu/etsu-works/7195.
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Nocturnal lizards are often active at temperatures that are sub-optimal for physiological functioning, a phenomenon that has been referred to as the ‘nocturnal paradox’. The purpose of this study was to investigate the general habitat and thermal preference of two species of nocturnal gecko in the genus Nephrurus with a focus on differences between preferred body temperatures determined under laboratory conditions and those measured in animals at the time of field collection. The Smooth Knob-tailed gecko (Nephrurus levis) and the Pale Knob-tailed Gecko (N. laevissimus) inhabit the desert environment of Uluru Kata-Tjuta National Park in the Northern Territory of Australia. Habitat preferences were determined by documenting capture locations for these species while thermal preferences were determined using laboratory-based thermal gradients. Analysis of habitat use demonstrated a significant difference in habitat preference between the two species. Nephrurus levis was most often in Spinifex sandplain and mulga shrubland and N. laevissimus was most often found around sand dune habitats. Fieldactive body temperatures of both species ranged from 14.5 °C to 32.2 °C and were significantly correlated with air and ground temperature at the time of capture. The thermal preference (Tpref) of N. levis (mean day Tpref mid = 29.1 °C and mean night Tpref 24 = 28.2 °C, n = 19) and N. laevissimus (mean day Tpref mid = 29.5 °C and mean night Tpref 24 = 27.8 °C, n = 27) were not significantly different, although both species exhibited significantly higher daytime and night-time preferred body temperatures than body temperatures observed in the field. Body size did not affect thermal preference for either species. As such, the thermal preferences of these species support the concept of the nocturnal paradox. Additionally, it has been suggested that the characteristic swollen tail tip displayed by all Nephrurus species may play a role in assessing the thermal environment. While not investigated extensively here, combined data for both species demonstrated that individuals oriented their tail toward the heat source in thermal gradients significantly more than expected if orientation were random.
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Sadlier, Ross Allen. "Systematic Studies on the Scincid Lizards of New Caledonia." Thesis, Griffith University, 2010. http://hdl.handle.net/10072/366402.
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My studies undertaken over the past 30 years have identified the existence of an exceptionally rich and highly diverse scincid lizard fauna in New Caledonia, one typified by regional and localised endemism at a level not indicated by earlier studies. The patterns of broad and finer-scale endemism revealed in the phylogenetic studies indicate a complex evolutionary history for the scincid lizard fauna, one which reflects the historical complexity of the island’s environment, and provides a window into the likely processes that shaped the present day biota. Further, it places the evolution of the New Caledonian lizard fauna in a broader regional context, identifying it as intimately linked with the endemic New Zealand skink fauna, and challenging current conventional theories of a recent post emersion Oligocene origin for the New Caledonia biota.Thesis (PhD Doctorate)
Doctor of Philosophy by Publication (PhD)
Griffith School of Environment
Science, Environment, Engineering and Technology
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Freeman, Alastair B. "An ecological study of the lizard fauna of Kaitorete Spit, Canterbury." Lincoln University, 1994. http://hdl.handle.net/10182/273.
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Baited pitfall traps were used to sample the lizard fauna at Birdlings Flat on Kaitorete Spit, Canterbury. Four species had been recorded previously from this area; Leiolopisma maccanni Patterson and Daugherty, Leiolopisma nigriplantare polychroma Patterson and Daugherty, Leiolopisma lineoocellatum (Dumeril and Dumeril) and Hoplodactylus maculatus (Gray). Three of these species (L. maccanni, L. n. polychroma and H. maculatus) were captured during the course of the study. The aim of this present study was to examine the nature of the ecological relationship among these three species at Birdlings Flat. Capture data indicated that L. maccanni was almost entirely confined to the dunelands while L. n. polychroma was associated exclusively with shrublands on old dune ridges behind the sand dunes. H. maculatus' distribution encompassed both of these major habitats. Separation on the basis of habitat was thought to be the most important niche variable for these two diurnal skinks. There was some temporal separation in activity of these two species, with L. maccanni active earlier in the day than L. n. polychroma. However, there was a high degree of overlap in the activity periods of these two species. Temporal differentiation between the nocturnal gecko H. maculatus and the two diurnal skinks is thought to be an important means by which these species coexist. The most common prey items consumed by all three species were Diptera, Araneae, C. propinqua seeds, Hemiptera, unidentified arthropod eggs, Coleoptera and Hymenoptera. Dietary differences between the two skink species were apparent although these differences appeared to be related to the preferred habitats of the respective species. Density estimates for L. maccanni varied between 1050/ha and 1850/ha while L. n. polychroma density varied between 200/ha and 400/ha. The density of H. maculatus was not calculated but appeared to be intermediate to the density of the two skink species. The apparent disappearance of L. lineoocellatum from an area where they were once relatively common is cause for concern. There is no obvious reason for this decline although it may be related to the combined impacts of predation, collection and habitat disturbance.
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Middleton, Danielle Mary Rose Lea. "The prevalence of Salmonella and the spatial distribution of its serovars amongst New Zealand's native lizards : a thesis presented in partial fulfillment of the requirements for the degree of Master of Science in Zoology at Massey University, Palmerston North, New Zealand." Massey University, 2008. http://hdl.handle.net/10179/906.
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This thesis considers the prevalence and spatial distribution of Salmonella serovars amongst wild endemic lizards on offshore islands around the coast of New Zealand. The mean test prevalence of faecal excretion of Salmonella was 4.7%. Skinks (Scincidae) were more likely (8.5%) to be carriers of Salmonella than geckos (1.6%). Each island was host to between one and three Salmonella serovars that were not found on any other islands in this study. Two exceptions were Salmonella Bousso and Salmonella Mana which were found on two islands within the same geographical area. Based on the findings of this study, different islands are likely to be hosts to different Salmonella serovars which could have implications for future translocations of native lizards. I also assessed the prevalence and spatial distribution of faecal excretion of Salmonella, Aeromonas and Hafnia alvei within Mana Island. The prevalence of Salmonella on Mana Island was estimated at 5.8%. Salmonella was found predominantly in skinks (10.0%) and less often in geckos (4.1%). H. alvei was found at a prevalence of 1.9%. No Aeromonas species were cultured from any of the cloacal swabs, suggesting that the 95% confidence interval for the true prevalence is 0-3%. Each site sampled in this study was host to one or more unique serovar of Salmonella not found at any of the other sites. The results of this study indicate that Salmonella serovars may become established within populations of lizards and is not spread between them. This may be due to a lack of dispersal of lizards between sites, raising important considerations for the translocation of native lizards. I investigated the prevalence of faecal excretion of Salmonella, H. alvei and Aeromonas by New Zealand native lizards from two captive populations. The mean prevalence of faecal excretion of Salmonella in the captive lizards sampled was 11.5%. There was a higher prevalence of Salmonella within captive population A (22.0%) than in population B (3.6%). No Aeromonas was cultured from any of the lizards. H. alvei was found at a prevalence of 5.2%. The prevalence of Salmonella and H. alvei was significantly higher in captive lizards than in wild populations. Captive lizards may, therefore, not be appropriate founders for new populations of wild lizards. Finally I assessed the different efficiencies of two media and two temperatures in isolating six Salmonella serovars from a reptilian source. All serovars grew equally well at 37°C and 27°C. For most serovars XLD agar was the more successful media than MacConkey agar but the success of different culture media depended on the serovar being cultured. Because lizards are frequently host to a wide range of Salmonella serovars, screening samples using multiple microbiological methods is likely to give the best chance of isolating all Salmonella serovars present.
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Jain, Dharamdeep. "Humidity Driven Performance of Biological Adhesives." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1510053266807976.
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Lettink, Marieke, and n/a. "Adding to nature : can artificial retreats be used to monitor and restore lizard populations?" University of Otago. Department of Zoology, 2008. http://adt.otago.ac.nz./public/adt-NZDU20080715.091040.
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Artificial retreats are increasingly used to sample animal populations and in attempts to boost animal numbers in degraded habitats. Here, I test potential applications of artificial retreats for lizards inhabiting a coastal environment of high conservation value (Kaitorete Spit, New Zealand). I first conducted a pitfall-trapping survey examining the distribution and relative abundance of lizards in duneland, farmland and shrubland habitats, and tested the influence of trap placement on capture rates. Capture rates of the diurnal skinks Oligosoma maccanni (McCann�s skink) and O. nigriplantare polychroma (common skink) were highest in duneland and farmland, respectively, and were most sensitive to the distance separating traps from the nearest cover (the greater the distance, the lower the capture rate). Captures of O. lineoocellatum (spotted skink) and Hoplodactylus maculatus (common gecko) were rare.
Secondly, in separate chapters I test the utility of artificial retreats for monitoring: 1) a preference trial examining relative use of three types of artificial retreats by skinks (O. maccanni and O. n. polychroma) and geckos (H. maculatus); 2) a comparison of the effectiveness of artificial retreats relative to pitfall traps for detecting cryptic and primarily nocturnal geckos (H. maculatus) following translocation; and 3) capture-recapture estimation of population parameters (survival and abundance) of H. maculatus. I found that: 1) geckos strongly preferred retreats made of Onduline over corrugated iron and concrete tiles, whereas skinks exhibited no apparent preferences; 2) artificial retreats were more effective than pitfall traps for detecting geckos following translocation; and 3) monthly survival and recapture probabilities of geckos varied with age-class and over time. Estimated survival was unexpectedly low, possibly due to excessive trap spacing. I developed a new capture-recapture model specifically for population size estimation with data from artificial retreats, which gave estimates that were up to 50% greater than those predicted by conventional capture-recapture models. I caution that permanent placement of artificial retreats in long-term studies may be inappropriate for estimation of population parameters due to potential habitat-enhancement effects and/or altered predation risk.
Thirdly, I conducted a capture-recapture field experiment, using a replicated Before-After-Control-impact (BACI) design, to test the relative effects of habitat manipulation (artificial retreat addition) and partial predator removal (by fencing) on annual survival of duneland skink (O. maccanni) populations. Survival increased at sites with predator exclosures, but not at control sites or following the addition of artificial retreats, either alone or in combination with a predator exclosure. The magnitude of the increase in survival for the exclosure-only treatment was small, but sufficient to change the trajectory of an apparently stable population into an increasing one, suggesting that the population is limited by predators. Predator control, but not the addition of artificial retreats, is predicted to benefit O. maccanni.
To conclude, the Onduline design developed here appears to be particularly useful for sampling cryptic, terrestrial geckos; however, artificial retreats must be used appropriately to avoid bias arising from habitat-enhancing effects and/or altered predation risk. The restoration value of artificial retreats requires further testing on other species and in areas where natural retreat sites are limited.
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Koch, Claudia [Verfasser]. "The Herpetofauna of the Peruvian dry forest along the Andean valley of the Marañón River and its tributaries, with a focus on endemic iguanians, geckos and tegus : Squamata: Iguanidae, Phyllodactylidae, Teiidae / Claudia Koch." Bonn : Universitäts- und Landesbibliothek Bonn, 2014. http://d-nb.info/1048091481/34.
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Kabiri, Farnaz Kabiri. "Gecko Adhesion on Soft Surfaces." University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1516061596336554.
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Menguc, Yigit. "Gecko-Inspired, Controlled Adhesion and Its Applications." Research Showcase @ CMU, 2012. http://repository.cmu.edu/dissertations/188.
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Gecko feet stick to almost anything, in almost any condition (including underwater and in space), but do not stick unintentionally, do not stick to dirt, and enable the gecko to literally run up the walls. When climbing a smooth surface, geckos can attach and detach each foot very quickly (detaching a foot takes 15 milliseconds) and with almost no noticeable force, but if attached perfectly they could theoretically hold tens of times their body weight. In contrast to gecko adhesion, conventional adhesives, made of soft tacky materials, tend to leave residues, pick up dirt easily, stick to themselves strongly and are useless underwater. Gecko feet rely on completely different principles, utilizing arrays of tiny mechanical structures made of very stiff protein which react to pressing and dragging with some very smart behavior. This thesis work is primarily concerned with taking inspiration from the principles of gecko-adhesion in order to control the attachment of synthetic structured adhesives.
We present gecko-inspired angled elastomer micropillars with flat or round tip endings as compliant pick-and-place micromanipulators. The pillars are 35 μm in diameter, 90 μm tall, and angled at an inclination of 20°. By gently pressing the tip of a pillar to a part, the pillar adheres to it through intermolecular forces. Next, by retracting quickly, the part is picked from a given donor substrate. During transferring, the adhesion between the pillar and the part is high enough to withstand disturbances due to external forces or the weight of the part. During release of the part onto a receiver substrate, the contact area of the pillar to the part is drastically reduced by controlled vertical or shear displacement, which results in reduced adhesive forces. The maximum repeatable ratio of pick-to-release adhesive forces was measured as 39 to 1. We find that a flat tip shape and shear displacement control provide a higher pick-to-release adhesion ratio than a round tip and vertical displacement control, respectively. We present a model of forces to serve as a framework for the operation of this micromanipulator. Finally, demonstrations of pick-and-place manipulation of μm-scale silicon microplatelets and a cm-scale glass cover slip serve as proofs of concept. The compliant polymer micropillars are safe for use with fragile parts, and, due to exploiting intermolecular forces, could be effective on most materials and in air, vacuum, and liquid environments.
We present a study of the self-cleaning and contamination resistance phenomena of synthetic gecko-inspired adhesives made from elastomeric polyurethane. The phenomenon of self-cleaning makes the adhesive foot of the gecko robust against dirt, and makes it effectively sticky throughout the lifetime of the material (within the molting cycles). So far synthetic gecko adhesives fail to capture this behavior and self-cleaning remains the least studied characteristic in the field geckoinspired adhesives. In this work we use two distinct arrays of micropillars with mushroom-shaped tips made from polyurethane. The two geometries we use all have the same aspect ratios of pillar height to base diameter of about 2 to 1, and all have mushroom tips that are twice the diameter of base. The pillar tip diameters are 20 μm and 95 μm, and we will refer to them as the small and large pillars, respectively. We contaminate the adhesives with simulated dirt particles in the form of well-characterized soda lime glass spheres ranging in diameter from 1 to 250 μm. Both micropillar arrays recovered adhesive strength after contamination and cleaning through dry, shearing contact with glass. In a best case scenario, we found that large pillars contaminated with 150-250 μm diameter particles can rid the tips of contaminating particles completely and recover 90% of the initial adhesive strength. This finding is significant because it is the first demonstration of adhesion recovery through dry self-cleaning by contact to a non-sticky cleaning substrate. The degree to which adhesion is recovered is superior to any conventional adhesive and is nearly identical to the gecko itself.
This thesis presents a study of controlling adhesion in gecko-inspired adhesives. This control is achieved by maximizing or minimizing attachment strength on demand by simple mechanical loading, and enables robotic manipulation tasks and the recovery of adhesion after contamination. Looking forward, we can predict what is possible for gecko-inspired adhesives if the discoveries in this thesis are implemented, and if other shortcomings in the field are resolved. Looking at the applications already under development, it seems clear that medical adhesives have great potential, and climbing robots might achieve significant utility. In consumer products, gecko-adhesives might replace Velcro®and zippers in clothing, and might become a critical component in sports gear, e.g. soccer goal keeper and rock climber gloves. The reversible, controllable nature of the adhesion, as well as its incredible bonding strength, suggests more impressive possibilities for gecko-inspired adhesives: perhaps it might act as a fastener for temporary or emergency construction. We might yet see rolls of single-sided and double-sided gecko-tape sold in hardware stores, not as a replacement for duct tape, but as a replacement for nails, staples and screws.
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Yu, Lan. "Adhesive Force of a Single Gecko Seta." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1523202746417773.
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Najem, Johnny F. "Gecko-Inspired Electrospun Flexible Fiber Arrays for Adhesion." University of Akron / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=akron1340465711.
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Wong, Andrew Carlton Edward. "Longitudinal studies on tooth replacement in the leopard gecko." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/54273.
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The leopard gecko is an emerging reptilian model for the molecular basis of indefinite tooth replacement. Here we characterize the tooth replacement frequency and pattern of tooth loss in the normal adult gecko. We chose to perturb the system of tooth replacement by activating the Wingless signaling pathway (Wnt). Misregulation of Wnt leads to supernumerary teeth in mice and humans. We hypothesized by activating Wnt signaling with LiCl, tooth replacement frequency would increase. To measure the rate of tooth loss and replacement, weekly dental wax bites of 3 leopard geckos were taken over a 35-week period. The present/absent tooth positions were recorded. During the experimental period, the palate was injected bilaterally with NaCl (control) and then with LiCl. The geckos were to be biological replicates. Symmetry was analyzed with parametric tests (repeated measures ANOVA, Tukey’s post-hoc), while time for emergence and total absent teeth per week were analyzed with non-parametric tests (Kruskal-Wallis ANOVA, Mann-Whitney U post-hoc and Bonferroni Correction). The average replacement frequency was 6-7 weeks and posterior-to-anterior waves of replacement were formed. Right to left symmetry between individual tooth positions was high (>80%) when all teeth were included but dropped to 50% when only absent teeth were included. Two animals were followed for 14 weeks after NaCl injections and 14 weeks after LiCl injections. NaCl did not affect the replacement dentition but LiCl delayed and disrupted the pattern of replacement. The phenotypes were more severe for one animal including 1) increased time before emergence, 2) increased total number of absent teeth per week, 3) a greater effect on anterior teeth and 4) disruption of symmetry. The most affected period began 7 weeks post LiCl injection. At the end of the study, in vitro CT scans of both animals revealed normal patterns of unerupted teeth however there was bone loss in one animal. Gecko tooth replacement is rapid enough to be useful for longitudinal studies. Between-animal variation is high when studying individual teeth therefore each animal should be used as its own control. Future work includes increasing the biological replicates and detailed molecular studies to confirm the effect of LiCl.Dentistry, Faculty of
Graduate
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Ramirez, Edward A. "Gecko Digital Hyperextension: Kinematics, Surface Roughness and Locomotor Performance." University of Akron / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=akron1333986580.
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Stark, Alyssa Yeager. "The Effect of Water on the Gecko Adhesive System." University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1405334677.
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Hill, Ginel Corina. "Dual-axis MEMS force sensors for gecko adhesion studies /." May be available electronically:, 2009. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
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Baker, Scott Michael. "Server Virtualization." Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1388%5F1%5Fm.pdf&type=application/pdf.
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Polakow, Daniel Adam. "Communication and sexual selection in the barking gecko (Ptenopus kochi)." Master's thesis, University of Cape Town, 1997. http://hdl.handle.net/11427/9511.
Full textAbstract:
Bibliography: leaves 167-206.This study focused on elucidating the functional significance of some aspects of the behaviour of Koch's barking gecko, Ptenopus kochi, during a field season conducted at the Desert Ecology Research Unit in Namibia for four months in 1995. Ptenopus kochi is a terrestrial species, and males were observed calling from their burrow entrances in the dry Kuiseb river bed during the hot summer months. First, aspects of competition among calling males were investigated. Calling males were seen to be non-randomly distributed relative to one another with evidence for regularity of spacing in dense aggregations. Sound intensity was investigated as the mechanism of spacing, and was mathematically modelled to gauge how the intensities of the calls of nearest-neighbour males overlapped. Results revealed a constancy at which neighbouring call intensities overlap, and playback experiments ratified the presence of a critical intensity threshold in the population, beyond which male tolerance broke down. These results suggested that spacing in P. kochi is vocally-mediated and that sound intensity acts as the proximate cue through which individuals gauge the closeness of neighbouring males. Second, the inter-relationships between call features of P. kochi's vocalisation, and how these features related to both intrinsic (morphological) and extrinsic (ambient) sources of variability were analytically explored. The principles of information theory and individual recognition by voice were used to gauge the variation manifest in the features of P. kochi's call. A novel statistical method for disentangling the influence of incidental sources of variation from 'signal' features in animal voices was developed. Results showed how once the predictable covariance in call structure was removed, the calls of P. kochi males were rendered statistically indistinguishable from one another. Several descriptor measures of P. kochi's vocalisation were seen to be highly dependent on meteorological determinants, as was nightly chorus duration. Lastly, mate-choice in P. kochi was explored using correlational evidence. Results revealed that mating success was closely linked to individual male differences in display effort and chorus site burrow activity, and less to morphological or territorial characteristics. Counter-intuitively, a positive relationship between call rate and chorus site residency was found in males, suggesting a possible role for classical condition-dependence in the evolution of female mate preference. Aspects of mate choice, together with the emergent importance of residency in this study were discussed and some ideas suggested for further research.
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Amaral, Paulo Alexandre Paixão. "Interface de instrumentos para veículo eléctrico Gecko: Merula - Redes sociais." Master's thesis, Universidade de Évora, 2011. http://hdl.handle.net/10174/12376.
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O principal objetivo deste trabalho e o desenvolvimento do painel de instrumentos
do ve culo el etrico Gecko Merula. Para tal, foi de nido um conjunto de princ pios
de apresenta c~ao de informa c~ao em ve culos e foi tamb em de nido, para a plataforma
Java e para a plataforma Android, um ambiente de desenvolvimento que permite
a de ni c~ao de pain eis de instrumentos de modo
ex vel. De forma a fazer uso
das liga c~oes sociais estabelecidas entre os utilizadores do Facebook foi de nida uma
aplica c~ao denominada Ve culoSocial que faz uso destas liga c~oes de forma a ltrar
conte udos de localiza c~ao num mapa. O ambiente de desenvolvimento de nido foi
testado numa plataforma teste, de forma a estudar o tempo de desenho dos componentes
no ecr~a. As interfaces do ve culo Gecko Merula e do Ve culoSocial foram
avaliadas com base nos princ pios de apresenta c~ao de informa c~ao em ve culos. A
partir dos testes de desempenho ao ambiente de desenvolvimento concluiu-se que,
para a plataforma de teste, o mesmo n~ao dever a de nir um n umero de componentes
demasiado elevado no painel de instrumentos de um ve culo, de forma a n~ao afetar
a precis~ao do painel. Da avalia c~ao das interfaces das aplica c~oes concluiu-se que e
necess aria a realiza c~ao de testes futuros nas interfaces e tamb em que a aplica c~ao
Ve culoSocial n~ao garante uma resposta atempada a um pedido de input de utilizador; ### Abstract:
The main goal for this work is the development of a dashboard for the electric
vehicle Gecko Merula. For this purpose, it was de ned a set of vehicle information
presentation principles and it was also de ned, for the Java platform and for the
Android platform, a development environment that produces in a
exible way a
vehicle dashboard. To make use of the social connections between users of Facebook,
it was de ned an application named Ve culoSocial that uses these social connections
in order to lter localization content to a map. The development environment was
tested, on a test platform, in order to study the drawing time of the components on
the screen. Gecko Merula and Ve culoSocial's interfaces were evaluated based on the
vehicle information presentation principles. From the performance tests performed
on the development environment it was concluded that, for the test platform, the
environment should not de ne an excessively high number of components on a vehicle
dashboard, so that it doesn't a ect the dashboard's precision. From the evaluation
of the applications' interface it was concluded that future interface tests are required
and that the Ve culoSocial application does not guarantee a timely response to a
user's input request.
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Tocher, Mandy Darlene. "The New Zealand common gecko Hoplodactylus maculatus: an ecophysiological comparsion of two isolated populations." Thesis, University of Canterbury. Biological Sciences, 1992. http://hdl.handle.net/10092/1431.
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Thermophysiological traits of two isolated Hoplodactylus maculatus populations were investigated to test adpatations to climate. Geckos were collected from Craigieburn (high altitude, generally cooler site) and Banks Peninsula. If climatic conditions at respective sites influenced physiology, I expected geckos from Craigieburn to exhibit cold-adapted physiological traits, whilst Banks Peninsula geckos would exhibit traits more characteristic of a warmclimate species. To this end I investigated four thermophysiological parameters: metabolism (SMR), preferred body temperature (PBT), locomotory performance and critical thermal minimum (CTMin). I hypothesized that if climate had an effect on SMR, Craigieburn geckos would exhibit higher levels of SMR which typically characterise other coolclimate reptiles. Craigieburn geckos displayed an average relative elevation of SMR over Banks Peninsula geckos of 26%. Furthermore, Craigieburn geckos appeared to be 'geared' towards lower body temperatures and exhibited a greater acclimatory and acclimatizatory ability of SMR. The PBT of Craigieburn geckos was consistently elevated above Banks Peninsula geckos. This finding was somewhat paradoxical in light of previous studies of this parameter. A closer examination of the ecology of the two populations is required to clarify the adaptive significance of a higher PBT in geckos from a cooler climate. With respect to locomotory performance, I hypothesized that if thermal extremes influenced activity, Craigieburn geckos would exhibit activity patterns which help ameliorate the adverse effects of cold temperature. Craigieburn geckos did in fact have greater independence of activity to temperature than Banks Peninsula geckos, especially over lower body temperatures. The final parameter investigated, that of the critical thermal minimum, failed to distinguish the populations decisively. However there was some evidence of a greater acclimatizatory and acclimatory range in Craigieburn geckos, providing somewhat limited support for a population difference. Investigations into all four parameters lead me to conclude that populations of Hoplodactylus maculatus from Craigieburn and Banks Peninsula are physiologically distinct and warrant a revision of nomenclature.
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Cafariello, Christopher. "The Identification of MTF2-specific Synthetic Lethal Interactions in Refractory Acute Myeloid Leukemia Using CRISPR." Thesis, Université d'Ottawa / University of Ottawa, 2019. http://hdl.handle.net/10393/39886.
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Acute myeloid leukemia (AML) is a disease characterized by overproduction of abnormally differentiated, hyper-proliferative myeloid cells known as blasts in bone-marrow and blood. Our laboratory has previously demonstrated that loss of epigenetic repression by the polycomb repressive complex 2 (PRC2), which is mediated by complex member metal response element binding transcription factor 2 (MTF2), drives chemo-resistance resulting in refractory AML. In this study, to identify MTF2-specific synthetic lethal interactions, a genome-scale CRISPR Knock-out (GeCKO) synthetic lethal screen was performed in matched MTF2-deficient and rescued THP-1 cells both in the absence and presence of the induction chemotherapeutic cytarabine. Following careful analysis of screening data using specialized software, 104 highly significant MTF2-specific synthetic lethal interactions as well as 15 cytarabine-specific synthetic lethal interactions were identified. Reduced stringency upon analysis helped to identify an additional seven MTF2-specific synthetic lethal interactions that could be targeted with commercially available small-molecule inhibitors. Among eight small molecule inhibitors, two DNA Polymerase A/Ribonucleotide Reductase Catalytic Subunit M1 (POLA/RRM1) dual inhibitors (clofarabine and fludarabine) were shown to induce toxicity with specificity for MTF2-deficient THP-1 cells at low concentrations only in the absence of cytarabine.
In the future, further testing of the therapeutic potential of clofarabine and fludarabine in treating MTF2-deficient AML will be conducted in patient derived bone-marrow aspirates which better represent the true clonal and hierarchical nature of this life-threatening malignancy. Furthermore, lentiviral delivery of short-hairpin RNAs (shRNAs) targeting highly significant, non-enzymatic MTF2 and cytarabine-specific synthetic lethal interactions will be performed in both THP-1 cells as well as in patient derived bone-marrow aspirates. Eventually, in vitro validated targets will be validated under in vivo conditions using a patient derived xenograft (PDX) preclinical animal model of AML using immunocompromised NOD scid gamma (NSG) mice.
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Klittich, Mena R. "Surface Interactions with Hierarchical Nanostructures: From Gecko Adhesion to Thermal Behavior." University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1499440265902425.
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Xu, Quan. "Dynamic Adhesion and Self-cleaning Mechanisms of Gecko Setae and Spatulae." Thesis, University of North Texas, 2013. https://digital.library.unt.edu/ark:/67531/metadc407812/.
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Geckos can freely climb on walls and ceilings against their body weight at speed of over 1ms-1. Switching between attachment and detachment seem simple and easy for geckos, without considering the surface to be dry or wet, smooth or rough, dirty or clean. In addition, gecko can shed dirt particles during use, keeping the adhesive pads clean. Mimicking this biological system can lead to a new class of dry adhesives for various applications. However, gecko’s unique dry self-cleaning mechanism remains unknown, which impedes the development of self-cleaning dry adhesives. In this dissertation we provide new evidence and self-cleaning mechanism to explain how gecko shed particles and keep its sticky feet clean. First we studied the dynamic enhancement observed between micro-sized particles and substrate under dry and wet conditions. The adhesion force of soft (polystyrene) and hard (SiO2 and Al2O3) micro-particles on soft (polystyrene) and hard (fused silica and sapphire) substrates was measured using an atomic force microscope (AFM) with retraction (z-piezo) speed ranging over 4 orders of magnitude. The adhesion is strongly enhanced by the dynamic effect. When the retraction speeds varies from 0.02 µm/s to 156 µm/s, the adhesion force increases by 10% ~ 50% in dry nitrogen while it increases by 15%~70% in humid air. A dynamic model was developed to explain this dynamic effect, which agrees well with the experimental results. Similar dynamic enhancement was also observed in aqueous solution. The influence of dynamic factors related to the adhesion enhancement, such as particle inertia, viscoelastic deformations and crack propagation, was discussed to understand the dynamic enhancement mechanisms. Although particles show dynamic enhancement, Gecko fabrillar hair shows a totally different trend. The pull off forces of a single gecko seta and spatula was tested by AFM under different pull-off velocities. The result shows that both the spatula and the seta have a rate independent adhesion response in normal retraction, which is quite different from micro-particles. Further research indicated the shape of the contact area was a key factor to the dynamic effect. In order to verify this hypothesis, artificial gecko spatula made of glass fibers was nanofabricated by a focus ion beam (FIB) and tested by AFM. These manmade spatulae also show a rate independent adhesion response. The dynamic adhesion of a single gecko seta and spatula were simulated with finite element analysis and the results also confirm the rate independent phenomena.. In conclusion, self-cleaning is induced by dynamic effect during gecko locomotion. The relative dynamic adhesion change between particles and seta makes it possible for gecko to shed the dirt particles while walking.Finally, the fatigue property of gecko seta was examined with the atomic force microscope under cyclic attachment/detachment process, mimicking gecko running. The adhesion force versus cycles has been tested and evaluated. Fatigue mechanism of gecko seta was also analyzed based on the experimental findings.
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Blow, Nathan S. Belote John. "Molecular evolution of visual pigments of the Tokay gecko and bluefin killifish." Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2004. http://wwwlib.umi.com/cr/syr/main.
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Rong, Zhuxia. "Structure-property relations in nanostructured materials : from solar cells to gecko adhesion." Thesis, University of Cambridge, 2014. https://www.repository.cam.ac.uk/handle/1810/245291.
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This thesis explores the structure-property relations in different nanostructured materials. Nanostructured polymer blends with interpenetrating network morphology of donor and acceptor materials have been considered ideal for organic bulk heterojunction photovoltaics. In this work we mainly investigate the self-organization of polymer blends via crystallization to generate functional nanostructures for organic electronics. Controlling morphology of organic photovoltaic thin films is crucial for the optimization of the device performance as there is a fine balance of exciton generation and separation as well as charge transport. To better understand the bulk heterojunction morphology, we first investigated the structure formation of poly (3-hexylthiophene) (P3HT)/ phenyl-C61- butyric-acid methyl ester (PCBM) system. Crystallization-induced phase separation has been found to drive the formation of a nanostructure in the blends, the size of which is determined by the intrinsic 10 nm length scale of semicrystalline P3HT. The mixing of PCBM within amorphous P3HT interlayers does not disrupt the crystallinity of the P3HT. P3HT crystallization expels PCBM into the spherulitic interlamellar amorphous layers, where it enriches to its miscibility limit. Above the solubility limit, PCBM aggregates start to form. The results suggest that the crystallization of P3HT and the enrichment of PCBM in interlamellar regions give rise to interconnected donor and acceptor phases those are close to the optimal bulk heterojunction structure. This structure formation mechanism is manifested by the good photovoltaic performance of spherulitic P3HT/PCBM films. Structural studies of P3HT/poly[(9,9-dioctyfluorene)-2,7-diyl-alt-(4,7-bis(3-hexylthien-5- yl)-2,1,3-benzothiadiazole)-2', 2"-diyl] (F8TBT) are presented. P3HT/F8TBT system exhibits a crystallization-driven structure formation similar to the P3HT/PCBM system despite the existence of a miscibility gap. The lamellar crystallization of P3HT is not perturbed by the addition of F8TBT. X-ray scattering studies indicate that F8TBT is mixed in the interlamellar amorphous phase up to a solubility limit, while a bulk heterojunction framework is established by the crystalline lamellae of P3HT. The excess F8TBT is accommodated at amorphous grain boundaries as well as the film/substrate interface. The structural studies are correlated with the photovoltaic device performance of P3HT/F8TBT films which exhibit spherulitic morphology. Devices based on spherulitic films show moderate efficiencies with improved fill factors but decreased photocurrents in comparison to that of thermal annealing condition. The results suggest that the nanostructure formation in P3HT/F8TBT blends is determined by the crystallization of P3HT, resulting in a structural size that are beneficial for exciton dissociation, while the F8TBT segregation at the substrate interface impair the device performance. The phase separation behavior in crystalline/crystalline blends consisting of P3HT and polyethylene oxide (PEO) is investigated. The self-assembly of P3HT in solution induces vertical segregation in blend films, in comparison to typical lateral polymer phase separation structures from non-aggregated solutions. Thin film transistors based on P3HT/PEO blends show show a nearly undegraded charge carrier mobility at low P3HT content due to the formation of a layered structure with P3HT nanowire networks segregated at the dielectric surface. Finally, a diversion from morphology studies of polymer blends involves the biomimetic fabrication of hierarchical fibrillar structures to achieve gecko adhesion. The hierarchical structures were fabricated based on polymer pillars tipping with carbon nanotube forests. The adhesion performance of the polymer-carbon nanotube hierarchical structures was tested by shear force measurements.
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Tejangkura, Thanawan. "Hybrid zone genetics and within-island diversity of the gecko Tarentola boettgeri." Thesis, Liverpool John Moores University, 2012. http://researchonline.ljmu.ac.uk/6162/.
Full textAbstract:
This study builds on a previous study that demonstrates the existence of deep mitochondrial lineages in the gecko Tarentola boettgeri within Gran Canaria (Gubitz et al. 2005). Here, I identified and analyzed the area where the two most divergent mitochondrial •lineages meet. The primary aim was to examine how geographical structuring of mtDNA has been maintained after secondary contact. MtDNA analyses used a 608 basepair fragment of the cytochrome b (cyt b) gene from 389 individuals sampled from 14 populations along a 32 km southeast (SE) transect across Gran Canaria. It revealed a low degree of mtDNA admixture and negligible gene flow across the contact zone. This led to the hypothesis that reproductive barriers may have formed between populations from different mtDNA lineages. Analyses of seven body dimension and scalation characters revealed that spatial patterns of morphological changes were not associated with the transition in mtDNA lineage frequency across the transect. This contrasted with another lizard species on the same island, Chalcides sexlineatus, in which phylogeography and morphology are highly correlated. This study identified ten unique microsatellite markers in T. boettgeri. Like morphology, analyses of these microsatellites did not reveal a pronounced spatial pattern of differentiation in the nuclear genome. These results appear to reject the hypothesis of a physical or genetic barrier to reproduction. Studies of micro satellites also suggested that T. boettgeri is a low dispersal species and this might explain the persistence of mtDNA contact zone. However, evidence of concordant spatial patterns between divergence in the nuclear genome and morphology was detected. The discordant spatial patterns of mitochondrial and nuclear genotype frequencies do not appear to be explained by sex-biased gene flow, and are difficult to understand because of expected interactions between the two genomes. Thus, further investigation is suggested to allow clarification of the causes of mito-nuclear discordance in T. boettgeri.
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Gomez, Patricia A. "Microhabitat preference of the introduced gecko Hemidactylus turcicus in an urban environment." [Gainesville, Fla.] : University of Florida, 2003. http://purl.fcla.edu/fcla/etd/UFE0001213.
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Caven, Barnaby. "Exploring a textile route to mimicking the adhesion properties of the gecko foot." Thesis, University of Leeds, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.536107.
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Song, Sukho. "Soft Robotic Grippers Using Gecko-Inspired Fibrillar Adhesives for Three-Dimensional Surface Grasping." Research Showcase @ CMU, 2017. http://repository.cmu.edu/dissertations/936.
Full textAbstract:
Researches on biological adhesive systems in nature have changed a perspective view on adhesion that it is not only the area of surface chemistry, but also mechanics of interfacial geometry which can significantly effect on fracture strength and load distribution on the contact interface. Various synthetic fibrillar adhesives in previous works have shown enhanced interfacial bond strength with the capacity of adhesion control by exploiting mechanical deformation of the elastomeric fibrillar structures inspired by geckos. However, control of the interfacial load distribution has been focused on the size of micro-contact with single or a few of micro-/nano-fibers on planar surface, and not for a large contact area on complex three-dimensional (3D) surfaces. This thesis work aims at investigating principles of the interfacial load distribution control in multi-scale, ranging from micro-contact with single micro-fiber to a centimeter-scale contact with a membrane-backed micro-fiber array on non-planar 3D surfaces. The findings are also applied for developing a soft robotic gripper capable of grasping a wide range of complex objects in size, shape, and number, expanding the area of practical applications for bio-inspired adhesives in transfer printing, robotic manipulators, and mobile robots. This paper comprises three main works. First, we investigate the effect of tip-shapes on the interfacial load sharing of mushroom-shaped micro-fibrillar adhesives with precisely defined tipgeometries using high resolution 3D nano-fabrication technique. For a large area of non-planar contact interface, we fabricate fibrillar adhesives on a membrane (FAM) by integrating micro-fibers with a soft backing, which enables robust and controllable adhesion on 3D surfaces. Picking and releasing mechanism for the maximal controllability in adhesion are discussed. Finally, we propose a soft robotic architecture which can control the interfacial load distribution for the FAM on 3D surfaces, solving an inherit dilemma between conformability and high fracture strength with the equal load sharing on complex non-planar 3D surfaces.
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Yan, Kai. "Calcium binding proteins and GAD immunoreactivity in the auditory system of Gekko Gecko." College Park, Md.: University of Maryland, 2008. http://hdl.handle.net/1903/8193.
Full textAbstract:
Thesis (M.S.) -- University of Maryland, College Park, 2008.Thesis research directed by: Dept. of Biology. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Gualdino, Miguel Ângelo da Silva. "Interface de instrumentos para veículo eléctrico Gecko Merula - sistema de navegação por satélite." Master's thesis, Universidade de Évora, 2012. http://hdl.handle.net/10174/12200.
Full textAbstract:
O objetivo deste trabalho e o desenvolvimento de um painel de instrumentos para o
ve culo el etrico Gecko Merula. Para o seu desenvolvimento foi feito um levantamento
de princ pios para de ni c~ao do painel de instrumentos. O painel de instrumentos foi
desenvolvido na plataforma Java para de ni c~ao dos instrumentos presentes no painel
de instrumentos. Foi desenvolvido um ambiente de desenvolvimento para cria c~ao de
interfaces gr a cas de nidas no documento XML. De forma a complementar o painel
de instrumentos foi desenvolvida um sistema de navega c~ao por sat elite que faz uso
da localiza c~ao do ve culo para c alculo de itiner arios para um determinado destino
com base em mapas online. As interfaces propostas foram avaliadas pelos princ pios
de apresenta c~ao de informa c~ao em ve culos e pelo tempo de desenho, mem oria consumida
da interface do painel de instrumentos e do sistema de navega c~ao. Com base
nos resultados obtidos conclui-se que o painel de instrumentos n~ao dever a conter
demasiados componentes pois prejudicar a a aten c~ao do condutor e eventualmente a
velocidade de atualiza c~ao dos valores apresentados no painel. O painel de instrumentos
proposto permite de nir e alterar os v arios componentes gr a cos no documento
XML de forma
ex vel; ### Abstract:
The objective of this work is the development of an instrument panel for the electric
vehicle Gecko Merula. A survey of principles for setting the instrument panel was
done for its development. The instrument panel was developed on the Java platform.
It was implemented a development environment to create a graphical user
interfaces speci ed in the XML document. In order to complement the instrument
panel a satellite navigation system has been developed. This system makes use of
the vehicle's location to calculate itineraries to a particular destination based on
online maps. The proposed interface was evaluated by: principles of presentation
of information in vehicles; and drawing time; memory consumption of the interface
of the instrument panel and navigation system. Based on the achieved results it
was concluded that the instrument panel should not include too many components
because it may prejudice the driver's attention and the accuracy of the values presented
on the panel. This proposed instrument panel allows the designers to set and
change the various graphical components on the XML document in a
exible way.
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Aquino, Andrea. "GECO." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2011. http://amslaurea.unibo.it/2390/.
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Ginebre, Emmanuel. "Geometry-dependence of the adhesive strength of biomimetic, micropatterned surfaces." Thesis, Linköpings universitet, Mekanik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-81067.
Full textAbstract:
Pressure sensitive adhesive surfaces are often inspired by nature. Miming the toe-surface of gecko, engineered surfaces made of thousands of micro-pillars show promising adhesive properties. This surfaces, covered with cylindrical pillars arranged into a pattern have adhesive properties greatly dependent on the geometrical characteristics. In this thesis, have been studied successively two models of micro-patterned surfaces, one two-dimensional, the other in three-dimensional using a FEM tool. Varying geometry parameters, has been determined optimal geometries to improve adhesive strength on these biomimetic, micropatterned surfaces. This study concludes to the non-adaptability of one-level scale micropatterned surface to large area of adhesion, to the strong advantage from the point of adhesion per contact area for high aspect ratio at each level of the geometry and study the opportunity of hierarchical structures. Some further suggestions of improvements to adhesion properties are discussed in the final chapter.