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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.
151

Real-Time Detection of Mitochondrial Inhibition at Frog Motor Nerve Terminals Using Increases in the Spatial Variance in Probability of Transmitter Release

Provan, Spencer D., Miyamoto, Michael D. 13 February 1995 (has links)
The effects of Hg2+, methyl mercury, and flufenamic acid, all of which inhibit mitochondria, were examined at frog motor nerve terminals. Unbiased estimates of m (no. of transmitter quanta released), n (no. of functional release sites), p (probability of release), and vars p (spatial variance in p) were obtained using K+-induced asynchronous neurosecretion (m, n and p not having the same definitions as with nerve-evoked release). Transient but significant increases in m, n, p and vars p were found with all three agents. These findings indicate that mitochondrial inhibition and release of sequestered Ca2+ can be detected as a real-time increase in vars p. The results also suggest that changes in vars p might be used to differentiate between cellular (membrane) and subcellular (organellar) actions of drugs at the nerve terminal.
152

Dubbeleggade miniatyryxor : En studie om neolitiska bärnstensminiatyrer / Double-edged miniature axes : A study about neolithic miniature axes in amber

Karlsson, Amanda January 2023 (has links)
Den här studien är en utforskning av dubbeleggade miniatyryxor av bärnsten som hittas i neolitiska gravar. Tre gravplatser har presenterats: ett flatmarksgravfält i Borgeby, flatmarksgravar i Ajvide på Gotland, och tre gånggrifter i Danmark. Dubbeleggade miniatyrer av bärnsten hittas i alla. Genom att använda praktikteori och begreppet habitus är syftet att uppsatsen ska ge insikt i varför miniatyrerna uppträder i Borgeby, och vad de kan ha haft för betydelse i samhället. En komparativ metod har använts för att jämföra gravplatserna, för att undersöka om det finns några likheter eller skillnader mellan dem. Resultatet visar att människorna i Borgeby hade kontakter med omvärlden. Bärnstenen var importerad från Danmark eller inspirerad av den danska trattbägarkulturen, och gravskicket i sig är inspirerat av den gropkeramiska kulturens gravar. / The study is an examination of double-edged miniature amber axes found in neolithic graves. Three different gravesites stand at the center of the essay: a flat grave field at Borgeby in Skåne, flat graves at Ajvide on Gotland, and three different megalithic passage graves in Denmark. Double-edge miniatures in amber appear in all of them. Using practice theory and the conceptof habitus the essay aims to give an insight in why they appear at Borgeby, as well as what double-edged axes might have meant to the people depositing them in graves. A comparative analysis of the above-mentioned gravesites will also be made, to examine whether any obvious similarities or differences exist between them. The results show that people in Borgeby had connections to the surrounding world. The miniature amber objects seem to be imported from Denmark or inspired by Danish shapes, whereas the graves themselves seem to be inspired by pitted ware culture.
153

Role of Adenosine A1 Receptors in Native Coronary Atherosclerosis, In-stent Stenosis, and Coronary Blood Flow Regulation in Metabolic Syndrome and Exercise

Long, Xin 08 April 2010 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / Adenosine is widely thought to elicit coronary vasodilation and attenuate smooth muscle cell (SMC) proliferation, thereby providing cardioprotection. We cloned the porcine adenosine A1 receptor (A1R) subtype and found that it paradoxically stimulated proliferation of cultured coronary SMC by the extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) signaling pathways, thus suggesting A1R dysregulation could play a role in coronary artery disease (CAD), restenosis, and regulation of coronary blood flow (CBF). We utilized the Ossabaw swine model of metabolic syndrome (MetS) to test the hypothesis that A1R activation contributes to development of CAD, in-stent stenosis, and CBF regulation. Swine were fed standard chow (Lean) or excess calorie atherogenic diet for over 20 weeks, which elicited MetS characteristics and coronary atherosclerosis compared to Lean. We observed increased A1R in native CAD in MetS, which was reversed by exercise training, and upregulation of A1R expression and A1R-ERK1/2 activation in an in vitro organ culture model of CAD. Intracoronary stent deployment followed by different durations of recovery showed A1R upregulation occurred before maximal in-stent stenosis in vi vivo. More importantly, selective A1R antagonism with 8-cyclopentyl-1, 3-dipropylxanthine (DPCPX)-eluting stents decreased coronary ERK1/2 activation and reduced in-stent stenosis comparable to Taxus® (paclitaxel-eluting stents). A1R antagonism potentiated vasodilatory effects of some vasodilators other than adenosine in porcine coronary microcirculation under basal conditions. Short-term exercise training around stenting prevented stent-induced microvascular dysfunction and attenuated native atheroma in the genetically lean Yucatan swine. Conclusions: A1R upregulation and activation contributes to coronary in-stent stenosis in vivo in MetS, plays a role in the development of coronary atherosclerosis in vitro, and might involve in CBF dysregulation in dyslipidemia and stenting. Exercise training decreased A1R expression in atherosclerosis, reduced native atheroma, and prevented stent-induced microvascular dysfunction. Selective pharmacological antagonism of A1R holds promise for treatment of CAD.
154

Tableaux for the Future

Curcio, Sally 28 October 2022 (has links)
My sculptural installations aim to elicit a sense of optimism and possibility through form, color, and mode of display. The work subverts the symbolic order by repurposing everyday forms and objects, allowing us to see the familiar as new, and thereby awakening us to what may be possible to formulate a better, more beautiful, more universally connected order.
155

The Memory Yields: B.F.A. Thesis Exhibition

Shanks, Sarah M. 03 June 2014 (has links)
No description available.
156

The Bronze Age Funerary Cups of Northern England

Hallam, Deborah L. January 2015 (has links)
Around the late third millennium BC small cup-shaped vessels began to appear in burial contexts across the North of England where they were found to be associated with Early Bronze Age funerary practices. Known by the name of incense cups, accessory vessels or miniature cups, their true purpose has been elusive. This study comprises an investigation of cups from Northern England and finds the tradition to be heavily influenced by Beaker culture practices resulting in the earliest cups emulating some attributes of Beaker ceramics. The Northern English Cup assemblage defies the current perception that all Cups are perforated as 63% are not; fabrics are found to be locally sourced and not imported and a review of the typology finds a strong regional adherence to the Food Vessel and Collared Urn tradition. Association in the grave with larger Urns is not as common as once believed and Cups have been found as the solitary ceramic indicating that they were important in their own right. Firing damage such as spalling has been interpreted as use of the funeral pyre for firing vessels prior to deposition with cremated remains and it is suggested that this is a recognisable signature of the cup tradition and therefore the name ‘funerary Cup’ is more appropriate. An active cross country trade network can be inferred from distributions of metalwork, precious materials and an affinity in some cases to Irish cups. / Prehistoric Society, Yorkshire Ladies Council for Education and the Andy Jagger Fund / The full text will be available at the end of the embargo period: 23rd Oct 2025
157

INVESTIGATION OF MECHANICAL PERFORMANCE AND FORMABILITY OF WELDED AND BRAZED SHEET MATERIALS

Shaker, Mohammed 11 1900 (has links)
In the last two decades or so, hybrid structures from dissimilar materials and/or sheet gauges have been developed to achieve weight reduction while maintaining or even improving structural performance such as stiffness, crash and impact behavior. In particular, welded and brazed sheet materials in the form of tailor blanks (TBs) are being increasingly used or considered for future applications in different applications such as automotive, aerospace and marine constructions as they offer attractive combination of strength and performance in applications where weight reduction is desirable. However, technical problems are often encountered during forming of TBs from dissimilar base sheet materials with different thickness and/or strength. These include weld line movement and non-uniform deformation. Additionally, there are premature weld failures due to the presence of softening zone (as in TBs made from advanced high strength steels), and brazed interface failure due to insufficient bonding and wetting (as in TBs made from steel and aluminum). These areas of forming of TBs need to be scientifically studied to advance the use of dissimilar materials. The current research involves an understanding of deformation and forming behavior of steel-to-steel tailor welded blanks (TWBs) made from advanced high strength steel (AHSS) such as dual phase (DP780) steel. The research also involves a study of deformation behavior of steel-to-aluminum tailor brazed blanks (TBBs). TWBs have been successfully joined using a relatively new welding techniques such as defocused fiber laser welding. TBBs, on the other hand, have been successfully produced by fiber Laser/MIG hybrid brazing and Cold Metal Transfer brazing (CMT). In addition, the formability of TWBs of different gauges and/or strengths was tested by using a new, simple and reproducible method of formability testing using a double-layer blank method. This method was devised and assessed for testing various steel combinations in different strain paths such that the weld line stayed in position with respect to forming tools and is subjected to the same stress and strain state as the parent material in the weld and its vicinity. Moreover, results from conventional stretch forming tests, single-layer blank, and the double-layer method were compared at the macroscopic level (such as weld line movement, forming limit etc.) as well as at the microscopic level (such as failure location within the weld and failure mode) to isolate the advantages of the proposed double-layer method. With regard to TBBs made by fiber Laser/MIG and CMT brazing methods, a fundamental knowledge and understanding of the local deformation behavior and material plastic ow in and around the brazed steel-aluminum interfaces were obtained by conducting miniature tensile mechanical tests that focus on continuous observation of the brazed region under a high magnification optical microscope to assess the ductility of the brazed joint and its capacity to carry the load during a material shaping process. / Thesis / Doctor of Philosophy (PhD) / In the last two decades or so, hybrid structures from dissimilar materials and/or sheet gauges have been developed to achieve weight reduction while maintaining or even improving structural performance such as stiffness, crash and impact behavior. In particular, welded and brazed sheet materials in the form of tailor blanks (TBs) are being increasingly used or considered for future applications in different applications such as automotive, aerospace and marine constructions as they offer attractive combination of strength and performance in applications where weight reduction is desirable. However, technical problems are often encountered during forming of TBs from dissimilar base sheet materials with different thickness and/or strength. These include weld line movement and non-uniform deformation. Additionally, there are premature weld failures due to the presence of softening zone (as in TBs made from advanced high strength steels), and brazed interface failure due to insufficient bonding and wetting (as in TBs made from steel and aluminum). These areas of forming of TBs need to be scientifically studied to advance the use of dissimilar materials.
158

Enchanting Pieces. : Miniature Copies in Augustus III's Art Collection from a Material and Contextual Perspective

Kluge, Linnéa Madita January 2024 (has links)
This master thesis examines miniature copies of large-scale paintings as a means of demonstrating knowledge, taste and power at the Saxon court during the reign of Augustus III. In two steps it sheds light on the processes behind the making and collecting of a type of miniature painting that has otherwise been disregarded by art historical research. With the help of five case studies from the Gemäldegalerie Alte Meister in Dresden and a theoretical approach rooted in materiality and contextual studies, it draws the attention of miniature research to the fact that miniature copies were not simple reproductions but the complex results of a multifaceted and prestigious production process. The study thus contributes to a broadened understanding of copies in miniature as valued art objects on their behalf as well as to position them in the larger framework of the 18th century's desire for art, connoisseurship and collecting.
159

Contribution to the Design and Implementation of Portable Tactile Displays for the Visually Impaired

Velazquez-Guerrero, Ramiro 06 1900 (has links)
This thesis explores the design, implementation and performance of a new concept for a low-cost, high-resolution, lightweight, compact and highly-portable tactile display. This tactile device is intended to be used in a novel visuo-tactile sensory substitution/supplemen-tation electronic travel aid (ETA) for the blind/visually impaired.Based on the psychophysiology of touch and using Shape Memory Alloys (SMAs) as the actuation technology, a mechatronic device was designed and prototyped to stimulate the sense of touch by creating sensations of contact on the fingertips.The prototype consists of an array of 64 elements spaced 2.6 mm apart that vertically actuates SMA based miniature actuators of 1.5 mm diameter to a height range of 1.4 mm with a pull force of 300 mN up to a 1.5 Hz bandwidth. The full display weights 200 g and its compact dimensions (a cube of 8 cm side-length) make it easy for the user to carry. The display is capable of presenting a wide range of tactile binary information on its 8 x 8 matrix. Moreover, both mechanical and electronic drive designs are easily scalable to larger devices while still being price attractive.Human psychophysics experiments demonstrate the effectiveness of the tactile information transmitted by the display to sighted people and show feasibility in principle of the system as an assistive technology for the blind/visually impaired.
160

Boundary layer streaks as a novel laminar flow control method

Sattarzadeh Shirvan, Sohrab January 2016 (has links)
A novel laminar flow control based on generation of spanwise mean velocity gradients (SVG) in a flat plate boundary layer is investigated where disturbances of different types are introduced in the wall-bounded shear layer. The experimental investigations are aimed at; (i) generating stable and steady streamwise streaks in the boundary layer which set up spanwise gradients in the mean flow, and (ii) attenuating disturbance energy growth in the streaky boundary layers and hence delaying the onset of turbulence transition. The streamwise streaks generated by four different methods are investigated, which are spanwise arrays of triangular/rectangular miniature vortex generators (MVGs) and roughness elements, non-linear pair of oblique waves, and spanwise-periodic finite discrete suction. For all the investigated methods the boundary layer is modulated into regions of high- and low speed streaks through formation of pairs of counter-rotating streamwise vortices. For the streaky boundary layers generated by the MVGs a parameter study on a wide range of MVG configurations is performed in order to investigate the transient growth of the streaks. A general scaling of the streak amplitudes is found based on empiricism where an integral amplitude definition is proposed for the streaks. The disturbances are introduced as single- and broad band frequency twodimensional Tollmien–Schlichting (TS) waves, and three-dimensional single and a pair of oblique waves. In an attempt to obtain a more realistic configuration compared to previous investigations the disturbances are introduced upstream of the location were streaks are generated. It is shown that the SVG method is efficient in attenuating the growth of disturbance amplitudes in the linear regime for a wide range of frequencies although the disturbances have an initial amplitude response to the generation of the streaks. The attenuation rate of the disturbance amplitude is found to be optimized for an integral streak amplitude of 30% of the free-stream velocity which takes into account the periodic wavelength of the streaky base flow. The stabilizing effect of the streamwise streaks can be extended to the nonlinear regime of disturbances which in turn results in transition to turbulence delay. This results in significant drag reduction when comparing the skin friction coefficient of a laminar- to a turbulent boundary layer. It is also shown that consecutive turbulence transition delay can be obtained by reinforcing the streaky boundary layer in the streamwise direction. For the streaky boundary layer generated by pair of oblique waves their forcing frequency sets the upper limit for the frequency of disturbances beyond which the control fails. / <p>QC 20160208</p>

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