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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

Three-dimensional FIB-SEM reconstruction of microtubule-organelle interaction in whole primary mouse beta cells

Müller, Andreas, Schmidt, Deborah, Xu, C. Shan, Pang, Song, D'Costa, Jolson Verner, Kretschmar, Susanne, Münster, Carla, Kurth, Thomas, Jug, Florian, Weigert, Martin, Hess, Harald F., Solimena, Michele 19 January 2021 (has links)
Microtubules play a major role in intracellular trafficking of vesicles in endocrine cells. Detailed knowledge of microtubule organization and their relation to other cell constituents is crucial for understanding cell function. However, their role in insulin transport and secretion is currently under debate. Here, we use Fib-Sem to image islet beta cells in their entirety with unprecedented resolution. We reconstruct mitochondria, Golgi apparati, centrioles, insulin secretory granules and micro-tubules of seven beta cells, and generate a comprehensive spatial map of microtubule-organelle interactions. We find that micro-tubules form non-radial networks that are predominantly not connected to either centrioles or endomembranes. Microtubule number and length, but not microtubule polymer density, vary with glucose stimulation. Furthermore, insulin secretory granules are enriched near the plasma membrane where they associate with microtubules. In summary, we provide the first 3D reconstructions of complete microtubule networks in primary mammalian cells together with evidence regarding their importance for insulin secretory granule positioning and thus supportive role in insulin secretion.
152

An Overview and Performance Guide to Manuel Ponce's Sonata III for Solo Guitar

Smith, Jay 08 1900 (has links)
Composed in 1927 and dedicated to Segovia, Ponce's Sonata III, one of the staples of the classical guitar repertoire, is the focus of this paper. To put this piece into proper perspective among Ponce's other works, biographical information leading up to the composition of the piece is presented first. Each of the three movements is then analyzed with regard to formal construction as well as harmonic and melodic language. Analysis is an important precursor to actually playing the piece, as Sonata III is a work that departs from Ponce's previous compositional style. The main portion of this paper addresses the preparation and interpretation of Sonata III. The insight gained through initial analysis of the piece is used to arrive at a musically satisfying interpretation of the work. Specific performance suggestions are included. Technical issues are addressed and possible solutions are presented. Alternate fingerings are provided to alleviate some of the common technical challenges the guitarist will encounter. A transcription and discussion of the Segovia revisions are also present. The paper concludes with general suggestions for improving performance that would be applicable to other works for guitar as well. This synthesis of biographical information, analysis, editorial options and performance suggestions, has hitherto never been never been done for this great work.
153

Loading Mode Dependent Effective Properties of Octet-truss Lattice Structures Using 3D-Printing

Challapalli, Adithya 05 1900 (has links)
Cellular materials, often called lattice materials, are increasingly receiving attention for their ultralight structures with high specific strength, excellent impact absorption, acoustic insulation, heat dissipation media and compact heat exchangers. In alignment with emerging additive manufacturing (AM) technology, realization of the structural applications of the lattice materials appears to be becoming faster. Considering the direction dependent material properties of the products with AM, by directionally dependent printing resolution, effective moduli of lattice structures appear to be directionally dependent. In this paper, a constitutive model of a lattice structure, which is an octet-truss with a base material having an orthotropic material property considering AM is developed. In a case study, polyjet based 3D printing material having an orthotropic property with a 9% difference in the principal direction provides difference in the axial and shear moduli in the octet-truss by 2.3 and 4.6%. Experimental validation for the effective properties of a 3D printed octet-truss is done for uniaxial tension and compression test. The theoretical value based on the micro-buckling of truss member are used to estimate the failure strength. Modulus value appears a little overestimate compared with the experiment. Finite element (FE) simulations for uniaxial compression and tension of octet-truss lattice materials are conducted. New effective properties for the octet-truss lattice structure are developed considering the observed behavior of the octet-truss structure under macroscopic compression and tension trough simulations.
154

Full-waveform inversion for large 3-D salt bodies

Kalita, Mahesh 05 May 2019 (has links)
The ever-expanding need for energy, including those related to fossil fuels, is behind the drive to explore more complicated regions, such as salt and subsalt provinces. This exploration quest relies heavily on recorded surface seismic data to provide precise and detailed subsurface properties. However, conventional seismic processing algorithms including the state-of-the-art full-waveform inversion (FWI) fail to recover those features in many areas of salt provinces. Even the industrial solution with substantial involvement of manual human-interpretation has faced challenges in many regions. In this thesis, I attempt to replace those manual, and somewhat erroneous, steps to the velocity building in salt provinces with a mathematically robust algorithm under the FWI machinery. I, specifically, regularize FWI by penalizing the velocity drops with depth with a new more flexible function. Although promising, FWI is computationally very expensive, especially for large 3D seismic data. It updates an initial guess of the model iteratively using the gradient of the misfit function, which requires lengthy computations and large memory space/disc storage. Based on the adjoint state method, gradient computation usually requires us to store the source wavefield, or include an additional extrapolation step to propagate the source wavefield from its temporary storage at the boundary. To mitigate this computational overburden, I propose an amplitude excitation gradient calculation based on representing the source wavefield history by a single, specifically the most energetic arrival. In this thesis, I also propose a novel-multiscale scheme based on ux-corrected transport (FCT) to reduce artifacts in the gradient direction due to the noise present in seismic data. FCT comprises of two finite difference schemes: a transport and a diffusion to compute the flux at a grid point. I observe a couple of benefits in FCT-based FWI. First, it yields a smooth gradient at the earlier iterations of FWI by promoting the lower frequency content of the seismic data. Second, it is easily compatible with the existing FWI code, and with any objective function. The multiscale strategy starts with a large smoothing parameter and relaxes it progressively to zero to achieve the final inverted model from traditional FWI.
155

An Electrochemical Immunoassay System for Measuring Circulating Protein Biomarkers of Pediatric Soft Tissue Sarcoma

Antwi, Ivy 01 August 2021 (has links)
Measurement of circulating protein biomarkers associated with disease can facilitate early detection, help guide treatment strategies and improve patient outcomes beyond current standards of care. The combination of inexpensive 3D-printed flow cells and electrochemical biosensors has recently emerged as a viable platform for low-cost, reliable biomarker measurements. Here, we report an electrochemical immunoassay system based on simple graphite electrode arrays, 3D-printed flow cells, and signal-generating magnetic bead bioconjugates for simultaneous detection of three biomarker proteins (cancer antigen 125 (CA-125), midkine (MK) and osteopontin (OPN)) associated with pediatric soft tissue sarcomas (PSTS). Magnetic bead bioconjugates are functionalized with large amounts of antibody and enzyme labels, electrode arrays are modified with gold nanoparticles and antibodies for specific capture of bioconjugate-labeled biomarkers, and 3D-printed flow cells facilitate their amperometric detection. Using this system, detection limits for CA-125, OPN and MK are 100 times lower than those obtained with commercial enzyme-linked immunosorbent assay (ELISA).
156

Methode zur dreidimensionalen Darstellung von Mechanismen in Mathcad

Baumgart, Rico 12 May 2009 (has links)
Mathcad hat sich bereits als benutzerfreundliche Mathematiksoftware in vielen Industriezweigen etabliert. An der Professur Maschinenelemente der TU Chemnitz werden mit Hilfe dieser Software Simulationsprogramme für Pkw-Klimaanlagen erstellt. Bei der Analyse und Optimierung von Produkten, wie z.B. dem Kältemittelverdichter, kann es für den Anwender hilfreich sein, den zu untersuchenden Mechanismus und die daran wirkenden Kräfte räumlich zu visualisieren. Dies kann, sofern ein CAD Modell vom Mechanismus vorhanden ist, beispielsweise mit der Software Pro Engineer erfolgen. Jedoch ist es auch möglich, ohne Zusatzsoftware mit einer sehr einfachen Methode Körper und Mechanismen direkt in Mathcad dreidimensional darzustellen und zu animieren. Anhand einiger Beispiele wird die Vorgehensweise in der Präsentation detailliert erläutert.
157

Dreidimensionale Darstellung und Kombination multimodaler Bilddaten in der Neurochirurgie

Meyer, Tobias, Podlesek, Dino, Kuß, Julia, Uhlemann, Falk, Leimert, Mario, Simank, Marita, Steinmeier, Ralf, Schackert, Gabriele, Morgenstern, Ute, Kirsch, Matthias 11 October 2008 (has links)
In der Neurochirurgie werden für die prä-, intra- und postoperative medizinische Bildgebung dreidimensionale Daten unterschiedlicher Modalitäten überlagert, segmentiert und visualisiert. Durch die Verknüpfung der multimodalen Daten erhofft man einen Informationsgewinn für Diagnose und Therapie. Dabei wird großer Wert auf die intuitive Handhabbarkeit und Verständlichkeit der Software gelegt. In einem neu entwickelten 3-D-Planungssystem wird insbesondere die Erfassung komplexer räumlicher Strukturen und die neurochirurgische Operationsplanung durch aktuelle 3-D-Interaktions- und Visualisierungstechnologien vereinfacht. Das Anwendungsspektrum des Systems wird durch die Entwicklung spezieller Algorithmen kontinuierlich erweitert, z. B. der automatischen Segmentierung und elastischen Registrierung von multimodalen Bilddaten, und kann somit an neue klinische Fragestellungen angepasst werden. / In neurosurgery, three-dimensional data from different modalities are registered, segmented and visualised for pre-, intraand post-operative medical imaging. A combination of the multimodal data sets provides additional information for the analyses of anatomic and functional correlations and for surgical planning. For routine use, it is important to design a software application that is simple and intuitive to use. A neurosurgical operation planning system is realised in combination with novel 3D-interaction and visualisation technologies. The development of additional functions, such as automatic segmentation and elastic registration, enhances the usability of the systems to approach further clinical objectives.
158

Studies on pharmacological activities of the cauliflower mushroom Sparassis crispa / ハナビラタケの薬理活性に関する研究

Kimura, Takashi 25 November 2013 (has links)
京都大学 / 0048 / 新制・論文博士 / 博士(農学) / 乙第12794号 / 論農博第2790号 / 新制||農||1019(附属図書館) / 学位論文||H25||N4806(農学部図書室) / 30813 / (主査)教授 栗原 達夫, 教授 植田 和光, 教授 平竹 潤 / 学位規則第4条第2項該当 / Doctor of Agricultural Science / Kyoto University / DFAM
159

Description of burrow structure for four crayfish species (Decapoda: Astacoidea: Cambaridae)

Florey, Cassidy L. 08 May 2019 (has links)
No description available.
160

Assessing Particulate and Chemical Emissions from Additive Manufacturing Processes

Gander, Nathan 04 November 2020 (has links)
No description available.

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