10,477 research outputs found
Multiscale X-Ray Analysis of Biological Cells and Tissues by Scanning Diffraction and Coherent Imaging
No full textThe past 70 years of muscle research have profoundly shaped our current understanding of the structure and function of muscle. X-ray diffraction became a key method in its structural analysis and yielded valuable insights into the molecular arrangement of the contraction apparatus. This work employs an extension of the X-ray diffraction methodology, scanning X-ray diffraction, for structural imaging of biological cells and tissue. With this technique periodicites in a structure on the order of several nanometers can be detected and, by raster scanning of the X-ray beam over the sample, images of the nano-structure can be computed. This makes it an ideal method to study e.g. local changes in the usually highly conserved distance between the myosin filaments in muscle cells. This work shows how such experiments can contribute to the understanding of cardiac tissue architecture and in particular to the development of the contraction apparatus of cardiac muscle cells upon cell maturation. This thesis also covers the fruitful combination of scanning X-ray diffraction and X-ray fluorescence microscopy in Parkinson-related biomedical research. While e.g. scanning X-ray diffraction was used to image the lamellar periodicity of the myelin sheath in brain tissue sections, by X-ray fluorescence microscopy we could verify a dishomeostasis of common trace elements in substantia nigra neurons due to Parkinson’s disease. To obtain a more complete picture of the complex, often very hierarchical, structure of biological cells and tissues, holographic X-ray imaging can be used. The holographic approach is used to directly image the electron density of the sample and greatly extends the resolution range covered in a scanning X-ray diffraction experiment. Due to its adjunct contrast, low dose requirement and experimental compatibility, holographic imaging can be advantageously paired with scanning X-ray diffraction. This work shows that, in combination, the two methods can cover three orders of magnitude in resolution, from approximately 10 nm to 10 μm. Lastly, an example is given where holographic imaging could be used to visualize barium aggregates in macrophages, not only in two- but also in three dimensions. To stabilize the macrophages for the holographic recording, the barium-loaded cells were trapped in an optical stretcher
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Enhanced colour encoding of materials discrimination information for multiple view dual-energy x-ray imaging
No full textThis thesis reports an investigation into dual-energy X-ray discrimination techniques. These techniques are designed to provide colour-coded materials discrimination information in a sequence of perspective images exhibiting sequential parallax. The methods developed are combined with a novel 3D imaging technique employing depth from motion or kinetic depth effect (KDE). This technique when applied to X-ray images is termed KDEX imaging and was developed previously by the university team for luggage screening applications at security checkpoints. A primary motivation for this research is that the dual-energy X-ray techniques, which are routinely incorporated into ‘standard’ 2D luggage scanners, provide relatively crude materials discrimination information. In this work it was critical that robust materials discrimination and colour encoding process was implemented as the sequential parallax exhibited by the KDEX imagery may introduce colour changes, due to the different X-ray beam paths associated with each perspective image. Any introduction of ‘colour noise’ into the resultant image sequences could affect the perception of depth and hinder the ongoing assessment of the potential utility of the dual-energy KDEX technique. Two dual-energy discrimination methods have been developed, termed K-II and W-E respectively. Employing the total amount of attenuation measured at each energy level and the weight fraction of layered structures, a combination of the K-II and the W-E techniques enables the computation and extraction of a target objects’ effective atomic number (Zeff) and its surface density (ρS) in the presence of masking layers
The North is another country. by Nicolas Rothwell
No full texttag=1 data=The North is another country. by Nicolas Rothwell
tag=2 data=Rothwell, Nicolas
tag=3 data=Australian Magazine,
tag=6 data=16/17 November 1996
tag=7 data=20-33.
tag=8 data=NT%TOURISM
tag=10 data=Worse, better, stranger, wilder, but above all different from the rest of the country. Continuing his journey of discovery across Australia's Top half the author stops over in Darwin to hear all the truths and whispers about the North.
tag=11 data=1996/2/8
tag=12 data=96/0316
tag=13 data=CABWorse, better, stranger, wilder, but above all different from the rest of the country. Continuing his journey of discovery across Australia's Top half the author stops over in Darwin to hear all the truths and whispers about the North
Snakebite vulnerability analysis and optimization of access to health in the Terai region of Nepal
No full textThis data includes four sets of geospatial rasters resulting from travel time and vulnerability analysis of the Terai region of Nepal for multiple scenarios, as described in the original publication. Additionally, the ReadMe.txt file provides extra information on the characteristics of the files
X-ray Cluster Cosmology
No full textFormation of dark matter halos is sensitive to the expansion rate of the Universe and to the growth of structures under gravitational collapse. Virialization of halos heats the gaseous intra-cluster medium to high temperatures, leading to copious emission of photons at X-ray wavelengths. We summarize the progress of X-ray surveys in determining cosmology using galaxy clusters.We review recent cosmological results based on cluster volume abundance, clustering, standard candles, extreme object statistics, and present relevant theoretical considerations. We discuss clusters as gravitation theory probes and present an outlook on future developments.Peer reviewe
Grace S. Fong, Herself an Author : Gender, Agency, and Writing in Late Imperial China, 2008
No full textZufferey Nicolas. Grace S. Fong, Herself an Author : Gender, Agency, and Writing in Late Imperial China, 2008. In: Études chinoises, n°28, 2009. Numéro spécial sur le droit chinois. pp. 243-247
New Necklaces: 400 Designs in Contemporary Jewellery
No full textAfter the successful New Rings and New Earrings, New Necklaces is the third book curated by jeweller and author Nicolas Estrada, from classic forms and materials to the most daring, experimental and surprising ideas, each of the 500 necklaces included in this book has something that makes it unique and relates strongly to today's social, cultural and artistic reality. With prefaces by German jeweller Julia Wild and Leo Caballero, owner of the Barcelona gallery Klimt 02, specialised in contemporary jewellers
How Did I Get to Princess Margaret? (And How Did I Get Her to the World Wide Web?)
No full textThe paper explores the growing use of
tools from the arts and humanities for investigation
and dissemination of social science research.
Emerging spaces for knowledge transfer, such as
the World Wide Web, are explored as outlets for
"performative social science". Questions of ethnics
and questions of evaluation which emerge from
performative social science and the use of new
technologies are discussed. Contemporary thinking
in aesthetics is explored to answer questions
of evaluation. The use of the Internet for productions
is proposed as supporting the collective
elaboration of meaning supported by Relational
Aesthetics.
One solution to the ethical problem of performing
the narrations of others is the use of the writer's
own story as autoethnography. The author queries
autoethnography's tendency to tell "sad" stories and
proposes an amusing story, exemplified by "The
One about Princess Margaret" (see Appendix).
The conclusion is reached that the free and open
environment of the Internet sidelines the usual
tediousness of academic publishing and begins to
explore new answers to questions posed about
the evaluation and ethics of performative social
science
Parsimony-based pedigree analysis and individual-based landscape genetics suggest topography to restrict dispersal and connectivity in the endangered capercaillie
No full textConnectivity and dispersal are key components determining the persistence of fragmented populations. However, the assessment of dispersal rates and landscape factors affecting functional connectivity remains problematic for species living in small populations, even more so in stress-sensitive, rare or elusive species. In this study, we estimated current dispersal patterns in a regional population of the endangered capercaillie (Tetrao urogallus) using a novel, parsimony-based application of pedigree analysis. In spring 2003 and 2008, we systematically collected non-invasive samples of this forest bird species in five local populations in the north-eastern Pre-Alps of Switzerland. Based on 11 nuclear microsatellites, we identified 86 unique genotypes over the two sampling periods and determined levels of genetic structure. We investigated the relative impact of topography and land use on functional population connectivity by comparing inter-individual genetic distance with GIS-derived least-cost path models representing different dispersal scenarios. Results show that local populations are connected by dispersers, suggesting occasional contemporary gene flow. Mountain ridges were found to hamper capercaillie dispersal, while, at odds with our hypothesis, neither a broad valley nor land use type notably affected gene flow. These results suggest that our study region represents a patchy metapopulation. Our study illustrates how pedigree analysis and landscape genetic methods can significantly contribute to the understanding of dispersal and connectivity in rare and elusive species
Identification of author profiles through social networks
No full textThe aim of this paper is to compile dictionaries of slang words, abbreviations, contractions, and emoticons to help the pre-processing of texts published in social networks. The use of these dictionaries is intended to improve the results of the tasks related to data obtained from these platforms. Therefore, a hypothesis was evaluated in the task of identifying author profiles (author profiling).Silva, JesúsMaria Santodomingo, Nicolas EliasRomero, LigiaJorge, MarisolHerrera, MaritzaPineda Lezama, Omar Bonerg
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