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Nyongesa, Henry Okola. "Genetic based machine learning allied to multi-variable fuzzy control of anaesthesia." Thesis, University of Sheffield, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.295759.
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Laschewsky, André, H. Ringsdorf, and J. Schneider. "Oriented supramolecular systems-polymeric monolayers and multilayers from prepolymerized amphiphiles." Universität Potsdam, 1986. http://opus.kobv.de/ubp/volltexte/2008/1713/.
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Oriented polymeric membranes were originally prepared by polymerization or polycondensation of preoriented monomers. The introduction of hydrophilic spacer groups into the polymeric amphiphiles allowed the formation of highly ordered systems (monolayers, liposomes, multilayers) from prepolymerized amphiphiles: due to the partial decoupling of the different mobilities and orientation tendencies of the polymer chain and the amphiphilic side groups, these polymers are able to self-organize. In monolayer experiments the high order of these membranes could be demonstrated by their surface pressure area-diagrams. In addition the combination of order and mobility of these spacer groups containing polymeric amphiphiles allowed the formation of Langmuir-Blodgett-multilyers with a high layer correlation. Thus, disturbancies in highly oriented layers can be avoided normally taking place during the polymerization reaction (e.g. contractions) or oriented monomeric layers.
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Reimer, A. "Clumping effects on non-thermal particle spectra in massive star systems." Universität Potsdam, 2007. http://opus.kobv.de/ubp/volltexte/2008/1824/.
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Observational evidence exists that winds of massive stars are clumped. Many massive star systems are known as non-thermal particle production sites, as indicated by their synchrotron emission in the radio band. As a consequence they are also considered as candidate sites for non-thermal high-energy photon production up to gamma-ray energies. The present work considers the effects of wind clumpiness expected on the emitting relativistic particle spectrum in colliding wind systems, built up from the pool of thermal wind particles through diffusive particle acceleration, and taking into account inverse Compton and synchrotron losses. In comparison to a homogeneous wind, a clumpy wind causes flux variations of the emitting particle spectrum when the clump enters the wind collision region. It is found that the spectral features associated with this variability moves temporally from low to high energy bands with the time shift between any two spectral bands being dependent on clump size, filling factor, and the energy-dependence of particle energy gains and losses.
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Montenegro, Rivelino V. D. "Crystallization, biomimetics and semiconducting polymers in confined systems." Phd thesis, Universität Potsdam, 2003. http://opus.kobv.de/ubp/volltexte/2005/76/.
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populärwissenschaftlicher Abstract:<br />
Kristallisation, Biomimetik und halbleitende Polymere in räumlich begrenzten Systemen:<br />
Öl und Wasser mischen sich nicht, man kann aber aus beiden Flüssigkeiten Emulsionen herstellen, bei denen Tröpfchen der einen Flüssigkeit in der anderen Flüssigkeit vorliegen. Das heißt, es können entweder Öltröpfchen in Wasser oder Wassertröpfchen in Öl erzeugt werden. Aus täglichen Erfahrungen, z.B. beim Kochen weiß man jedoch, dass sich eine Emulsion durch Schütteln oder Rühren herstellen lässt, diese jedoch nicht besonders stabil ist. Mit Hilfe von hohen Scherenergien kann man nun sehr kleine, in ihrer Größe sehr einheitliche und außerdem sehr stabile Tröpfchen von 1/10000 mm erhalten. Eine solche Emulsion wird Miniemulsion genannt. <br />
In der Dissertation wurden nun z.B. Miniemulsionen untersucht, die aus kleinen Wassertröpfchen in einem Öl bestehen. Es konnte gezeigt werden, dass das Wasser in diesen Tröpfchen, also in den räumlich begrenzten Systemen, nicht bei 0 °C, sondern bei -22 °C kristallisierte. Wie lässt sich das erklären? Wenn man einen Eimer Wasser hat, dann bildet sich normalerweise bei 0 °C Eis, da nämlich in dem Wasser einige (manchmal ganz wenige) Keime (z.B. Schutzteilchen, ein Fussel etc.) vorhanden sind, an denen sich die ersten Kristalle bilden. Wenn sich dann einmal ein Kristall gebildet hat, kann das Wasser im gesamten Eimer schnell zu Eis werden. Ultrareines Wasser würde bei -22 °C kristallisieren. Wenn man jetzt die Menge Wasser aus dem Eimer in kleine Tröpfchen bringt, dann hat man eine sehr, sehr große Zahl, nämlich 1017 Tröpfchen, in einem Liter Emulsion vorliegen. Die wenigen Schmutzpartikel verteilen auf sehr wenige Tröpfchen, die anderen Tröpfchen sind ultrarein. Daher kristallisieren sie erst bei -22 °C.<br />
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Im Rahmen der Arbeit konnte auch gezeigt werden, dass die Miniemulsionen genutzt werden können, um kleine Gelatine-Partikel, also Nanogummibärchen, herzustellen. Diese Nanogummibärchen quellen bei Erhöhung der Temperatur auf ca. 38 °C an. Das kann ausgenutzt werden, um zum Beispiel Medikamente zunächst in den Partikeln im menschlichen Körper zu transportieren, die Medikamente werden dann an einer gewünschten Stelle freigelassen. In der Arbeit wurde auch gezeigt, dass die Gelatine-Partikel genutzt werden können, um die Natur nachzuahnen (Biomimetik). Innerhalb der Partikel kann nämlich gezielt Knochenmaterial aufgebaut werden kann. Die Gelatine-Knochen-Partikel können dazu genutzt werden, um schwer heilende oder komplizierte Knochenbrüche zu beheben. Gelatine wird nämlich nach einigen Tagen abgebaut, das Knochenmaterial kann in den Knochen eingebaut werden.<br />
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LEDs werden heute bereits vielfältig verwendet. LEDs bestehen aus Halbleitern, wie z.B. Silizium. Neuerdings werden dazu auch halbleitende Polymere eingesetzt. Das große Problem bei diesen Materialien ist, dass sie aus Lösungsmitteln aufgebracht werden. Im Rahmen der Doktorarbeit wurde gezeigt, dass der Prozess der Miniemulsionen genutzt werden kann, um umweltfreundlich diese LEDs herzustellen. Man stellt dazu nun wässrige Dispersionen mit den Polymerpartikeln her. Damit hat man nicht nur das Lösungsmittel vermieden, das hat nun noch einen weiteren Vorteil: man kann nämlich diese Dispersion auf sehr einfache Art verdrucken, im einfachsten Fall verwendet man einfach einen handelsüblichen Tintenstrahldrucker.<br>The colloidal systems are present everywhere in many varieties such as emulsions (liquid droplets dispersed in liquid), aerosols (liquid dispersed in gas), foam (gas in liquid), etc. Among several new methods for the preparation of colloids, the so-called miniemulsion technique has been shown to be one of the most promising. Miniemulsions are defined as stable emulsions consisting of droplets with a size of 50-500 nm by shearing a system containing oil, water, a surfactant, and a highly water insoluble compound, the so-called hydrophobe<br />
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1. In the first part of this work, dynamic crystallization and melting experiments are described which were performed in small, stable and narrowly distributed nanodroplets (confined systems) of miniemulsions. Both regular and inverse systems were examined, characterizing, first, the crystallization of hexadecane, secondly, the crystallization of ice. It was shown for both cases that the temperature of crystallization in such droplets is significantly decreased (or the required undercooling is increased) as compared to the bulk material. This was attributed to a very effective suppression of heterogeneous nucleation. It was also found that the required undercooling depends on the nanodroplet size: with decreasing droplet size the undercooling increases.<br />
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2. It is shown that the temperature of crystallization of other n-alkanes in nanodroplets is also significantly decreased as compared to the bulk material due to a very effective suppression of heterogeneous nucleation. A very different behavior was detected between odd and even alkanes. In even alkanes, the confinement in small droplets changes the crystal structure from a triclinic (as seen in bulk) to an orthorhombic structure, which is attributed to finite size effects inside the droplets. An intermediate metastable rotator phase is of less relevance for the miniemulsion droplets than in the bulk. For odd alkanes, only a strong temperature shift compared to the bulk system is observed, but no structure change. A triclinic structure is formed both in bulk and in miniemulsion droplets.<br />
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3. In the next part of the thesis it is shown how miniemulsions could be successfully applied in the development of materials with potential application in pharmaceutical and medical fields. The production of cross-linked gelatin nanoparticles is feasible. Starting from an inverse miniemulsion, the softness of the particles can be controlled by varying the initial concentration, amount of cross-link agent, time of cross-linking, among other parameters. Such particles show a thermo-reversible effect, e.g. the particles swell in water above 37 °C and shrink below this temperature. Above 37 °C the chains loose the physical cross-linking, however the particles do not loose their integrity, because of the chemical cross-linking. Those particles have potential use as drug carriers, since gelatin is a natural polymer derived from collagen.<br />
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4. The cross-linked gelatin nanoparticles have been used for the biomineralization of hydroxyapatite (HAP), a biomineral, which is the major constituent of our bones. The biomineralization of HAP crystals within the gelatin nanoparticles results in a hybrid material, which has potential use as a bone repair material.<br />
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5. In the last part of this work we have shown that layers of conjugated semiconducting polymers can be deposited from aqueous dispersion prepared by the miniemulsion process. Dispersions of particles of different conjugated semiconducting polymers such as a ladder-type poly(para-phenylene) and several soluble derivatives of polyfluorene could be prepared with well-controlled particle sizes ranging between 70 - 250 nm. Layers of polymer blends were prepared with controlled lateral dimensions of phase separation on sub-micrometer scales, utilizing either a mixture of single component nanoparticles or nanoparticles containing two polymers. From the results of energy transfer it is demonstrated that blending two polymers in the same particle leads to a higher efficiency due to the better contact between the polymers. Such an effect is of great interest for the fabrication of opto-electronic devices such as light emitting diodes with nanometer size emitting points and solar cells comprising of blends of electron donating and electron accepting polymers.
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Gentsch, Rafael. "Complex bioactive fiber systems by means of electrospinning." Phd thesis, Universität Potsdam, 2010. http://opus.kobv.de/ubp/volltexte/2010/4490/.
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Nanofibrous mats are interesting scaffold materials for biomedical applications like tissue engineering due to their interconnectivity and their size dimension which mimics the native cell environment. Electrospinning provides a simple route to access such fiber meshes. This thesis addresses the structural and functional control of electrospun fiber mats.
In the first section, it is shown that fiber meshes with bimodal size distribution could be obtained in a single-step process by electrospinning. A standard single syringe set-up was used to spin concentrated poly(ε-caprolactone) (PCL) and poly(lactic-co-glycolic acid) (PLGA) solutions in chloroform and meshes with bimodal-sized fiber distribution could be directly obtained by reducing the spinning rate at elevated humidity. Scanning electron microscopy (SEM) and mercury porosity of the meshes suggested a suitable pore size distribution for effective cell infiltration.
The bimodal fiber meshes together with unimodal fiber meshes were evaluated for cellular infiltration. While the micrometer fibers in the mixed meshes generate an open pore structure, the submicrometer fibers support cell adhesion and facilitate cell bridging on the large pores. This was revealed by initial cell penetration studies, showing superior ingrowth of epithelial cells into the bimodal meshes compared to a mesh composed of unimodal 1.5 μm fibers.
The bimodal fiber meshes together with electrospun nano- and microfiber meshes were further used for the inorganic/organic hybrid fabrication of PCL with calcium carbonate or calcium phosphate, two biorelevant minerals. Such composite structures are attractive for the potential improvement of properties such as stiffness or bioactivity. It was possible to encapsulate nano and mixed sized plasma-treated PCL meshes to areas > 1 mm2 with calcium carbonate using three different mineralization methods including the use of poly(acrylic acid). The additive seemed to be useful in stabilizing amorphous calcium carbonate to effectively fill the space between the electrospun fibers resulting in composite structures.
Micro-, nano- and mixed sized fiber meshes were successfully coated within hours by fiber directed crystallization of calcium phosphate using a ten-times concentrated simulated body fluid. It was shown that nanofibers accelerated the calcium phosphate crystallization, as compared to microfibers. In addition, crystallizations performed at static conditions led to hydroxyapatite formations whereas in dynamic conditions brushite coexisted.
In the second section, nanofiber functionalization strategies are investigated. First, a one-step process was introduced where a peptide-polymer-conjugate (PLLA-b-CGGRGDS) was co-spun with PLGA in such a way that the peptide is enriched on the surface. It was shown that by adding methanol to the chloroform/blend solution, a dramatic increase of the peptide concentration at the fiber surface could be achieved as determined by X-ray photoelectron spectroscopy (XPS). Peptide accessibility was demonstrated via a contact angle comparison of pure PLGA and RGD-functionalized fiber meshes. In addition, the electrostatic attraction between a RGD-functionalized fiber and a silica bead at pH ~ 4 confirmed the accessibility of the peptide.
The bioactivity of these RGD-functionalized fiber meshes was demonstrated using blends containing 18 wt% bioconjugate. These meshes promoted adhesion behavior of fibroblast compared to pure PLGA meshes.
In a second functionalization approach, a modular strategy was investigated. In a single step, reactive fiber meshes were fabricated and then functionalized with bioactive molecules. While the electrospinning of the pure reactive polymer poly(pentafluorophenyl methacrylate) (PPFPMA) was feasible, the inherent brittleness of PPFPMA required to spin a PCL blend. Blends and pure PPFPMA showed a two-step functionalization kinetics. An initial fast reaction of the pentafluorophenyl esters with aminoethanol as a model substance was followed by a slow conversion upon further hydrophilization. This was analysed by UV/Vis-spectroscopy of the pentaflurorophenol release upon nucleophilic substitution with the amines. The conversion was confirmed by increased hydrophilicity of the resulting meshes.
The PCL/PPFPMA fiber meshes were then used for functionalization with more complex molecules such as saccharides. Aminofunctionalized D-Mannose or D-Galactose was reacted with the active pentafluorophenyl esters as followed by UV/Vis spectroscopy and XPS. The functionality was shown to be bioactive using macrophage cell culture. The meshes functionalized with D-Mannose specifically stimulated the cytokine production of macrophages when lipopolysaccharides were added. This was in contrast to D-Galactose- or aminoethanol-functionalized and unfunctionalized PCL/PPFPMA fiber mats.<br>Biofunktionale Materialien gewinnen immer größere Bedeutung in biomedizinischen Anwendungen wie dem künstlichen Ersatz von Knochen oder Blutgefässe. Weiterhin können diese Stoffe nützlich sein, um die Wechselwirkung zwischen Biomaterialien und biologischen Systemen wie Zellen oder Organismen weiter zu erforschen. In diversen Studien konnten Größen wie dreidimensionaler Strukturaufbau, Oberflächentopographie, Mechanik und die Funktionalisierung mit bioaktiven Substanzen als Einflussfaktoren identifiziert werden, welche auf verschiedenen Größenskalen von makroskopisch bis nanoskopisch untersucht wurden und gegenwärtig erforscht werden. Bioinspiriert von Kollagenfasern, die als Strukturmotiv an verschieden Orten im menschlichen Körper vorkommen (z.B. extrazelluläre Matrix) konnte gezeigt werden, dass Fasermatten, die eine ähnliche Größendimensionen wie die vorher erwähnten Kollagenfasern (Ø ~ 500 nm) aufweisen, eine aussichtsreiche Gerüstmatrix darstellen. Eine einfache Methode Fasermatten in diesen Dimensionen herzustellen ist Elektrospinning, wobei typischerweise eine viskose Polymerlösung durch anlegen eines Hochspannungsfeldes verstreckt wird. Obwohl auf diese Weise hergestellte Fasermatten für gewisse Zelllinien eine ideale Zellwechselwirkung aufweisen, ist die Zellbesiedelung solcher Netzwerke, bedingt auch durch die kleinen Porendurchmesser, problematisch und bedarf meistens weiterer Prozessierungsschritte.
Diese Arbeit beschäftigt sich mit der einfachen Herstellung von strukturel und funktional kontrollierten Fasersystem mittels Elektrospinning. Der erste Teil behandelt ein Einschrittverfahren zum Elektrospinnen von bimodalen Fasermatten bestehend aus Nano- und Mikrofasern. In Zellstudien mit Epithelzellen konnte gezeigt werden, dass solche Netzwerke tiefer besiedelt werden als Matten bestehend aus unimodalen 1.5 μm dicken Fasern. Des Weiteren wurden diese Fasermatten für fasergerichtete Kristallisation von Kalziumcarbonat und – phosphat benutzt.
In einem zweiten Teil wurden 2 Strategien für die Faserfunktionalisierung mit Peptiden und Zuckermolekülen entwickelt. Zum einen wurde gezeigt, dass funktionale Peptidfasern durch Verspinnung einer Mischung von einem Peptid-Polymer-Konjugat mit einem kommerziellen Polymer hergestellt werden konnten. Zusätzlich wurde ein modularer Ansatz für die Herstellung von reaktiven Fasern ausgearbeitet, die anschließend mit Peptiden oder Zuckern funktionalisiert wurden. Die Bioaktivität der Zucker funktionalisierten Fasern konnte durch Zellversuche erfolgreich bestätigt werden.
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Note, Carine. "Influence of hydrophobically modified polyelectrolytes on nanoparticle synthesis in self-organized systems and in water." Phd thesis, kostenfrei, 2006. http://opus.kobv.de/ubp/volltexte/2007/1167/.
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Brocklehurst, Christopher Joseph. "Finite element studies of reinforced and unreinforced two-layer soil systems." Thesis, University of Oxford, 1993. http://ora.ox.ac.uk/objects/uuid:0cae9e18-c5c3-416c-914f-528873e90da7.
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The purpose of this study is to obtain an insight into the mechanisms by which a geosynthetic membrane influences the performance of a plane strain and an axisymmetric two-layer soil system, where the reinforcement is incorporated either into a layer of fill, or at the interface of a layer of fill overlying clay subgrade. New axisymmetric membrane and interface element formulations are developed and incorporated in to an existing large strain finite element code. A linear elastic model of behaviour is used for the membrane material and an elastic-perfectly frictional model, based on the Mohr-Coulomb yield function, is implemented for the interface. These new formulations both take account of large global displacement and rotation effects, although the interface element is constrained to small relative displacements, and are checked against small and large strain closed form test problems. The finite element equations are based on an Updated Lagrangian description of deformation. Plane strain finite element investigations into the significance of the resolution and relative size of the finite element mesh, and the differences between large and small strain analyses, are undertaken. For typical unreinforced and reinforced plane strain and axisymmetric two- layer soil systems a detailed analysis is presented of the soil displacements, strains, stresses, principal stress directions, mobilised fill friction angles and the stresses on the underside of the footing. A series of plane strain and some axisymmetric parametric studies of the various material properties is conducted, to assess the influences and relative importance of those variables to the performance of the two-layer soil system under monotonic loading. The study considers various reinforcement lengths and stiffnesses, fill depths and strengths, and different clay strengths. The mechanisms of reinforcement are identified through careful examination of the footing load-displacement response, the reinforcement tension and the stresses and displacements at the interfaces with the surrounding soil. A comparative study is also undertaken between the results obtained by the finite element model and those predicted by a plane strain and axisymmetric limit equilibrium design method. The effects of including a low friction membrane within an oil storage tank base, as secondary containment against oil leakage, are investigated by a series of axisymmetric finite element analyses.
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Ferguson, Kelly-Anne. "An investigation of isotropic and anisotropic magnetic field effects in fluorescent systems." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:12a062e9-7bc7-414f-84e6-d65717b6c120.
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Interest into the effects of weak static magnetic fields on chemical reactions involving spin correlated radical pairs has increased over the last few decades, particularly as scientists have become more curious about the mechanisms by which animals can sense and respond to small variations in the Earth's weak (50 µT) magnetic field. The magnetosensitivity of radical pairs, as dictated by the radical pair mechanism, lies at the heart of the most heavily supported hypothesis of this magnetoreception phenomenon. This thesis is concerned with the spectroscopic investigations of isotropic and anisotropic magnetic field effects in fluorescent systems. First of all, an introduction to spin chemistry and magnetoreception is presented. In chapter 3, the effects of weak radiofrequency oscillating fields when applied in combination with weak static fields are explored in isotropic solutions. The validity of the high-field model, typically used to describe spin dynamics in magnetic resonance, is tested and the effects of orientation and field strength on magnetic field effects are discussed in detail. In Chapter 4, a range of exciplex systems are studied by fluorescence methods and their energetics are explored. The factors which determine the formation of an exciplex, i.e. the complex equilibrium between the exciplex and the spin-correlated radical pair,are considered and used to assess the existence and magnitude of MFEs. Radical pair systems investigated, using MARY spectroscopy, with respect to their potential to act as model chemical compasses are introduced in chapter 5. Solid-state media are used to align the exciplex systems to detect any magnetic field direction dependence. Finally, in chapter 6, AMELIA, an experiment which can directly measure the anisotropic magnetic field response of a system, is presented and applied successfully to systems to detect directly the anisotropic field response of a photoexcited anthracene crystal.
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Klinkusch, Stefan. "Simulations of laser-induced correlated many-electron dynamics in molecular systems." Phd thesis, Universität Potsdam, 2011. http://opus.kobv.de/ubp/volltexte/2011/5544/.
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In this thesis, simulations of laser-driven many-electron dynamics in molecules are presented, i.e., the interaction between molecules and an electromagnetic field is demonstrated. When a laser field is applied to a molecular system, a population of higher electronic states takes place as well as other processes, e.g. photoionization, which is described by an appropriate model. Also, a finite lifetime of an excited state can be described by such a model.
In the second part, a method is postulated that is capable of describing electron correlation in a time-dependent scheme. This is done by introducing a single-electron entropy that is at least temporarily minimized in a further step.<br>Im Rahmen dieser Doktorarbeit werden Simulationen lasergetriebener Vielelektronendynamik in Molekülen präsentiert, d.h., die Wechselwirkung zwischen Molekülen und einem elektromagnetischen Feld wird demonstriert. Bei Laseranregungen finden nicht nur elektronische Übergänge statt, sondern auch weitere Prozesse wie die Photoionisation, die mit einem geeigneten Modell beschrieben wird. Auch die endliche Lebensdauer angeregter Zustände kann mit einem solchen Modell beschrieben werden.
Im zweiten Teil wird eine Methode postuliert, die fähig ist, die Elektronenkorrelation zeitabhängig zu beschreiben. Dies wird durch die Einführung einer Einelektronenentropie erreicht, die in einem weiteren Schritt zumindest kurzzeitig minimiert wird.
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Joyce, Kerry Eloise. "Public health decision making : the value of geographical information systems (GIS) mapping." Thesis, Northumbria University, 2007. http://nrl.northumbria.ac.uk/2652/.
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Technologies such as geographical information systems (GIS) have emerged during the past two decades as part of the Information Revolution and include functions such as data storage, management, integration, analysis and presentation. GIS have wide and diverse applications in disciplines such as engineering, business/marketing, urban planning and environmental management but remain underused in public health. The thesis reports the findings of a mixed methods study examining the views and perceptions of public health practitioners on the value of GIS mapping in decision-making. A case study design was chosen; the case issue (childhood lead [Pb] exposure) represents an example of the "case" which is defined as 'decision- making in public health'. The exploratory phase of the study combined heterogeneous data to produce a visualisation of lead contamination in Newcastle. The value of GIS in public health was explored in an interview phase. Twenty-two semi-structured interviews were conducted with decision-makers involved either directly or indirectly in public health practice. Interview recordings were transcribed and coded thematically for analysis. Decision-makers tended to be positive about the use of GIS in public health and many volunteered potential opportunities to apply GIS mapping techniques further. Four discourses were highlighted through analyses, namely: data origins (Ontological Discourse), status (Power Discourse), application (Functionality Discourse) and reciprocity (Collaboration Discourse). The power of maps to integrate multiple, disparate datasets was found to be important and respondents felt, overall, that GIS mapping was a democratic means of communication. Complexity frameworks are drawn upon to make sense of the research findings and to illuminate the need for non-reductionist models of decision-making in the public health context. The lessons learnt through this study can be translated to other fields, thereby sharing skills, knowledge and experience to promote collaboration and integrated thinking across the public health landscape.
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Mullaney, Benjamin R. "Halogen bonding interlocked host systems for recognition and sensing of anions." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:e3d75598-d025-4c69-aad3-9740c428a9b5.
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This thesis describes the synthesis of halogen bonding receptors for integration within interlocked anion host systems. Chapter 1 introduces the field of supramolecular chemistry, with a particular focus on anion recognition and sensing, halogen bonding, and the synthesis of mechanically interlocked structures. Chapter 2 describes the preparation and anion binding properties of carbazole-based receptor molecules. A systematic anion binding study on a series of halogen- and hydrogen-bonding 3,6-bis-triazolium carbazole acyclic receptors is described initially, followed by the development of a halogen bonding rotaxane. The anion and metal complexation properties of acyclic and macrocyclic systems incorporating the 1,8-bis-triazole carbazole motif are also presented. Chapter 3 details the synthesis and anion complexation investigations of halogen and hydrogen bonding naphthalene-based acyclic and interlocked rotaxane host molecules. Chapter 4 presents receptors based on the 4,4'-bis-triazole-2,2'-bipyridyl motif. A halogen bonding rhenium(I) bipyridyl complex is exploited in the development of a rotaxane host system which optically senses anions via luminescence purely through halogen bonding interactions. The anion recognition and sensing properties of diquat-based receptors are also investigated, and shown to exhibit optical and electrochemical responses to anions. Chapter 5 summarises the major conclusions from Chapters 2-4. Chapter 6 describes the experimental procedures used in the work, and includes characterisation data for the synthesised compounds. Supplementary information relating to crystallographic data, and absorption, luminescence and electrochemical studies, is provided in the Appendices.
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Ehland, Andreas. "Vibrations of precast and partially prestressed floor systems under moving loads : development of a dynamic fork-lift truck model for vibration serviceability analysis and its application." Thesis, University of Oxford, 2009. http://ora.ox.ac.uk/objects/uuid:9820a6a3-6b98-44b3-89e0-3aadb818b606.
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This project studies the dynamic response of a composite floor system to excitations from moving fork-lift trucks. The floor system analysed is a system of precast and partially prestressed double-tee elements with a cast in-situ topping. Currently, there are concerns whether the vibrations caused by fork-lift trucks might exceed acceptable limits due to an ongoing trend towards structures of higher slenderness. This study investigates the mechanical background of the excitation and the current design of the floor system. The study is divided into three major chapters: <strong>Dynamic fork-lift truck model</strong> A dynamic load model of a fork-lift truck is developed which can be used in the analytical verification of the vibration serviceability of structures. The model is based on tests performed on four fork-lift trucks in various configurations. The tests are analysed for the spectrum of accelerations. The analysis results in a simple two-degree-of-freedom model. Its only variables are velocity and time. All other values are constant throughout a simulation and depend on the geometry of the specific fork-lift truck and its payload. The frequencies and phase delays are constants and they are verified as eigen-frequencies of a three-degree-of-freedom model. <strong>FE-simulation of vibrations of a composite floor system</strong> The fork-lift truck model is applied to a three-dimensional model of a composite floor system. The finiteelement model is developed to simulate the construction process of the composite floor system and its influence on the in-service properties of the structure. As part of this work a preliminary investigation of the damping potential of the joint between precast and cast in-situ concrete is undertaken. A linear time-step analysis of the structure is performed and the nodal accelerations are analysed for their magnitude, dependence on the excitation and frequency content. <strong>Field test</strong> In order to verify the FE-model of the floor system and the results of the dynamic analysis a field test was undertaken: a floor system was monitored under service conditions. The field data comprise the accelerations of the floor and the forklift truck and the position of the truck relative to the points of measurement. A comparison of the field data and the simulation results proves the validity of both the dynamic fork-lift truck model and the FE-model of the floor system.
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Woolerton, Thomas William. "Development of enzymatic H2 production and CO2 reduction systems." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:393741ac-94b1-4d56-b680-d9a434db77e2.
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One of today’s most pressing scientific challenges is the conception, development and deployment of renewable energy technologies that will meet the demands of a rapidly increasing population. The motivation is not only dwindling fossil fuel reserves, but also the necessary curtailment of emissions of the greenhouse gas carbon dioxide (a product of burning fossil fuels). The sun provides a vast amount of energy (120,000 TW globally), and one major challenge is the conversion of a fraction of this energy into chemical energy, thereby allowing it to be stored. Dihydrogen (H₂) that is produced from water is an attractive candidate to store solar energy (a ‘solar fuel’), as are high energy carbon-containing molecules (such as CO) that are formed directly from carbon dioxide. One key aspect is the development of catalysts that are able to offer high rates and efficiencies. In biology, some microbes acquire energy from the metabolism of H₂ and CO. The biological catalysts - enzymes - that are responsible are hydrogenases (for the oxidation of H₂ to protons); and carbon monoxide dehydrogenases (CODHs, for the oxidation of CO to CO₂). These redox enzymes, containing nickel and iron as the only metals, are extraordinary in terms of their catalytic characteristics: many are fully reversible catalysts and offer very high turnover frequencies (thousands per second are common), with only tiny energy input requirements. This Thesis uses a hydrogenase from the bacterium Escherichia coli, and two CODHs from the bacterium Carboxydothermus hydrogenoformans, as the catalysts in H2 production and CO₂ reduction systems. Chapter 3 describes the concept and development not of a solar fuel system, but of a device that catalyses the water-gas shift reaction (the reaction between CO and water to form H₂ and CO₂) - a process of major industrial importance for the production of high purity H₂. Chapters 4, 5 and 6 detail photochemical CO₂ reduction systems that are driven by visible light. These systems, operating under mild, aqueous conditions, involve CODHs attached either to TiO₂ nanoparticles that are sensitised to visible light by the co-attachment of a ruthenium-based dye complex, or to cadmium sulfide nanomaterials that, having a narrow band gap, are inherently photoexcitable by visible light. The motivation here is not the construction of technological devices; indeed, the enzymes that are used are fragile, highly sensitive to oxygen, and impossible to scale to industrial levels. Rather, the drivers are those of scientific curiosity (can the incorporation of these remarkable biological catalysts enable the creation of outstanding solar fuel devices?), and of producing systems that serve as benchmarks and inspiration for the development of fully synthetic systems that are robust and scalable.
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Stansfield, Anthony Stewart. "Early modern systems of command : Queen Anne's generality, staff officers and the direction of allied warfare in the Low Countries and Germany, 1702-11." Thesis, University of Leeds, 2010. http://etheses.whiterose.ac.uk/2324/.
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Throughout the operations of the War of the Spanish Succession in the Low Countries and Germany, senior commanders such as John Churchill, duke of Marlborough, were aided, abetted and, on occasion, disrupted by a number of general and staff officers. These officers provided the mechanism by which supra-regimental command, military direction and management was effected. While these individuals possessed military dignity according to their rank and station, their real authority in the army was in no small part drawn from the powers and duties delegated to them by the commander-inchief, or assumed upon their own initiative; clear chains of command did not exist. Such officers functioned not only as vital elements in their own army, but within the broader context of the confederate warfare as a whole, in an army composed of English (later British), Dutch, Imperial, Danish and auxiliary German contingents. They came from diverse backgrounds and could possess constrasting political affiliations, aspirations and notions of duty. Their careers were governed as much by patronage and preference as any personal merit. A burgeoning sense of military duty was complicated by personal prejudice and the boundary between public and private endeavour was indistinct. Some officers gained wealth and financial security; others were ruined by the peculations of others.
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Young, Callum A. "Local structure/property relationships in functional materials." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:8eea6d96-5a48-4ed9-adad-e2b1fdc97acb.
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It is increasingly being realised that localised deviations from the average structure can play an important role in a material's properties, and hence an understanding of these deviations is essential when constructing a coherent picture of a system. In this thesis, both neutron and X-ray total scattering data have been collected and used to reveal information on three canonical systems: the high-temperature superconductor YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-x</sub>; the parent compound of the colossal magnetoresistive manganites, LaMnO<sub>3</sub>; and the oldest known magnetic material, Fe<sub>3</sub>O<sub>4</sub>. Reverse Monte Carlo refinements-using the RMCProfile implementation of the algorithm-have been used as the principal analysis technique, and the functionality of the RMCProfile program has been extended to allow the refinement of magnetic systems involving substitutional disorder. For YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-x</sub>, the focus of this thesis is on the apical Cu{O bond length. This is shown to have a bimodal distribution, but correlations in the displacements of both atoms disguise this fact in the average structure, thus resolving the apparent controversy that had existed between local- and average-structure probes. LaMnO<sub>3</sub> displays (what was thought to be) a simple order{disorder transition that results in the Jahn-Teller distortion becoming invisible in the average structure above ~ 750 K. Here it is shown that in fact the transition is more complicated, and involves a change in the symmetry of the Jahn-Teller distortion, whereby the long Mn-O bonds move from being opposite one another in the octahedra to being adjacent to one another. This new distortion still breaks the degeneracy of the system, and is consistent with a wide range of existing observations. Finally the low temperature structure of Fe<sub>3</sub>O<sub>4</sub> is examined using the updated RMCProfile code. The refinements show sensitivity to local structure variations, producing a bimodal Fe atom bond valence distribution. In addition, the refined magnetic spin configuration is presented, providing the first detailed description of the low-temperature magnetic structure. It is found to be a canted ferrimagnet, and appears to be consistent with Cc symmetry.
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Bruckner, Terri Ann. "Using an Argument-based Approach to Validity for Selected Tests of Spatial Ability in Allied Medical Professions Students." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1371562493.
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Shaw, Christopher. "How do sociomaterial networks involving large-scale automation come into being, persist and change over time, within a healthcare environment?" Thesis, Northumbria University, 2014. http://nrl.northumbria.ac.uk/21437/.
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The aim of this thesis is to develop a theoretical model to explore how sociomaterial networks, involving large-scale automation, come into being, persist and change over time, within a healthcare environment. It does so by bridging the gap between design, implementation and use of large-scale pathology automation (LSPA) within two United Kingdom (UK) National Health Service (NHS) laboratories. A longitudinal, multi-site, ethnographic approach was used, along with semi-structured interviews, template analysis and participant observation of LSPA ‘in-practice’. This research has suggested that design features, embedded within the material properties of LSPA, were purposefully intended to bring about organisational change. In both user organisations, the material affordances of LSPA resulted in anticipated skill mix changes. However, material constraints required the enforcement of changes to organisational routines, creating operational difficulties, which were then subsequently transferred across organisational boundaries by the researcher/manager. The identification of these sociomaterial affordances and constraints, in conjunction with humans acting as boundary objects, had the unintended consequence of influencing strategic decision making and initiating structural and cultural change. The development and practical application of the resulting SociomANTerial model allowed the researcher to trace the analytical history of these organisational changes over time and consider the impact of broader social structures such as power. Ultimately it is suggested that a greater emphasis on collaboration between users, designers and corporate agents will result in more innovative approaches for technology adoption and improved organisational design.
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Hildebrandt, Niko. "Lanthanides and quantum dots : time-resolved laser spectroscopy of biochemical Förster Resonance Energy Transfer (FRET) systems." Phd thesis, Universität Potsdam, 2006. http://opus.kobv.de/ubp/volltexte/2007/1268/.
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Förster Resonance Energy Transfer (FRET) plays an important role for biochemical applications such as DNA sequencing, intracellular protein-protein interactions, molecular binding studies, in vitro diagnostics and many others. For qualitative and quantitative analysis, FRET systems are usually assembled through molecular recognition of biomolecules conjugated with donor and acceptor luminophores. Lanthanide (Ln) complexes, as well as semiconductor quantum dot nanocrystals (QD), possess unique photophysical properties that make them especially suitable for applied FRET. In this work the possibility of using QD as very efficient FRET acceptors in combination with Ln complexes as donors in biochemical systems is demonstrated. The necessary theoretical and practical background of FRET, Ln complexes, QD and the applied biochemical models is outlined. In addition, scientific as well as commercial applications are presented.
FRET can be used to measure structural changes or dynamics at distances ranging from approximately 1 to 10 nm. The very strong and well characterized binding process between streptavidin (Strep) and biotin (Biot) is used as a biomolecular model system. A FRET system is established by Strep conjugation with the Ln complexes and QD biotinylation. Three Ln complexes (one with Tb3+ and two with Eu3+ as central ion) are used as FRET donors. Besides the QD two further acceptors, the luminescent crosslinked protein allophycocyanin (APC) and a commercial fluorescence dye (DY633), are investigated for direct comparison. FRET is demonstrated for all donor-acceptor pairs by acceptor emission sensitization and a more than 1000-fold increase of the luminescence decay time in the case of QD reaching the hundred microsecond regime. Detailed photophysical characterization of donors and acceptors permits analysis of the bioconjugates and calculation of the FRET parameters. Extremely large Förster radii of more than 100 Å are achieved for QD as acceptors, considerably larger
than for APC and DY633 (ca. 80 and 60 Å). Special attention is paid to interactions with different additives in aqueous solutions, namely borate buffer, bovine serum albumin (BSA), sodium azide and potassium fluoride (KF). A more than 10-fold limit of detection (LOD) decrease compared to the extensively characterized and frequently used donor-acceptor pair of Europium tris(bipyridine) (Eu-TBP) and APC is demonstrated for the FRET system, consisting of the Tb complex and QD. A sub-picomolar LOD for QD is achieved with this system in azide free borate buffer (pH 8.3) containing 2 % BSA and 0.5 M KF. In order to transfer the Strep-Biot model system to a real-life in vitro diagnostic application, two kinds of imunnoassays are investigated using human chorionic gonadotropin (HCG) as analyte. HCG itself, as well as two monoclonal anti-HCG mouse-IgG (immunoglobulin G) antibodies are labeled with the Tb complex and QD, respectively. Although no sufficient evidence for FRET can be found for a sandwich assay, FRET becomes obvious in a direct HCG-IgG assay showing the feasibility of using the Ln-QD donor-acceptor pair as highly sensitive analytical tool for in vitro diagnostics.<br>Förster Resonanzenergietransfer (FRET) spielt eine wichtige Rolle in biochemischen Anwendungen, wie z.B. DNA-Sequenzierung, intrazellulären Protein-Protein-Wechselwirkungen, molekularen Bindungsstudien, in-vitro-Diagnostik und vielen anderen. Zur quantitativen und qualitativen Analyse werden FRET Systeme normalerweise durch molekulare Erkennung von Biomolekülen, die mit Donator- und Acceptorluminophoren markiert sind, ermöglicht. Durch die besonderen photophysikalischen Eigenschaften sowohl von Lanthanidkomplexen (Ln-Komplexen), als auch Halbleiternanokristallen (sog. Quantenpunkten oder Quantumdots - QD), sind diese besonders für FRET Anwendungen geeignet. In der vorliegenden Arbeit wird effizienter FRET zwischen Ln-Komplexen und QD in biochemischen Systemen demonstriert. Die notwendigen theoretischen und praktischen Grundlagen über FRET, Ln-Komplexe, QD und die verwendeten biochemischen Modelle werden dargestellt, und wissenschaftliche als auch kommerzielle Anwendungen werden präsentiert.
FRET kann zur Messung von strukturellen Veränderungen und Dynamiken im Bereich von ca. 1 bis 10 nm verwendet werden. Der sehr starke und gut charakterisierte Bindungsprozess zwischen Streptavidin (Strep) und Biotin (Biot) wird als biomolekulares Modellsystem eingesetzt. Ein FRET System wird durch Streptavidinkonjugation mit Ln-Komplexen und QD-Biotinylierung etabliert. Drei Ln-Komplexe (einer mit Tb3+ und zwei mit Eu3+ als Zentralion) werden als Donatoren verwendet, und neben QD werden zwei weitere Acceptoren, das lumineszierende, quervernetzte Protein Allophycocyanin (APC) und ein kommerzieller Fluoreszenzfarbstoff (DY633), untersucht. FRET kann für alle Donator-Acceptor Paare nachgewiesen werden, zum einen durch sensibilisierte Acceptorlumineszenz und zum anderen durch eine über 1000-fach erhöhte Lumineszenzabklingzeit der QD mit über 100 Mikrosekunden. Mittels detailierter photophysikalischer Charakterisierung der Donatoren und Acceptoren können die Biokonjugate analysiert und die FRET Parameter berechnet werden. Für die QD FRET Systeme ergeben sich extrem große Försterradien von über 100 Å, die wesentlich größer sind als für APC und DY633 (ca. 80 bzw. 60 Å). Besondere Aufmerksamkeit gilt der Wechselwirkung mit den Zusatzreagenzien Boratpuffer, Bovines Serumalbumin (BSA), Natriumazid und Kaliumfluorid (KF) in den wässrigen Lösungen. Im Vergleich zum ausgiebig charakterisierten und vielfach verwendeten Donator-Acceptor Paar aus Europium-tris(Bipyridin) (Eu-TBP) und APC wird eine mehr als 10-fache Senkung der Nachweisgrenze für das FRET-System, bestehend aus Tb-Komplex und QD, erreicht. In azidfreiem Boratpuffer (pH 8,3) mit 2 % BSA und 0,5 M KF wird eine subpicomolare QD-Nachweisgrenze für dieses System aufgezeigt. Um den Transfer des Strep-Biot Modellsystems in eine echte in-vitro-diagnostische Anwendung zu demonstrieren, werden zwei Immuntests zum HCG-(Humanes Choriongonadotropin)-Nachweis untersucht. Sowohl HCG als auch monoklonale anti-HCG Maus-IgG-(Immunoglobulin G)-Antikörper werden mit dem
Tb-Komplex bzw. mit QD markiert. Obwohl kein ausreichender Nachweis für FRET in
einem immunometrischen Assay (oder Sandwichassay) erbracht werden kann, wird FRET in einem direkten HCG-IgG Assay erzielt, wodurch die Realisierbarkeit von Ln-QD Donator-Acceptor Paaren zur hochsensitiven Anwendung in der in-vitro-Diagnostik gezeigt werden kann.
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Mathibela, Bonolo. "Situational awareness in autonomous vehicles : learning to read the road." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:f9a788c4-1ce5-4733-be2b-ab3918ed079b.
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This thesis is concerned with the problem of situational awareness in autonomous vehicles. In this context, situational awareness refers to the ability of an autonomous vehicle to perceive the road layout ahead, interpret the implied semantics and gain an awareness of its surrounding - thus reading the road ahead. Autonomous vehicles require a high level of situational awareness in order to operate safely and efficiently in real-world dynamic environments. A system is therefore needed that is able to model the expected road layout in terms of semantics, both under normal and roadwork conditions. This thesis takes a three-pronged approach to this problem: Firstly, we consider reading the road surface. This is formulated in terms of probabilistic road marking classification and interpretation. We then derive the road boundaries using only a 2D laser and algorithms based on geometric priors from Highway Traffic Engineering principles. Secondly, we consider reading the road scene. Here, we formulate a roadwork scene recognition framework based on opponent colour vision in humans. Finally, we provide a data representation for situational awareness that unifies reading the road surface and reading the road scene. This thesis therefore frames situational awareness in autonomous vehicles in terms of both static and dynamic road semantics - and detailed formulations and algorithms are discussed. We test our algorithms on several benchmarking datasets collected using our autonomous vehicle on both rural and urban roads. The results illustrate that our road boundary estimation, road marking classification, and roadwork scene recognition frameworks allow autonomous vehicles to truly and meaningfully read the semantics of the road ahead, thus gaining a valuable sense of situational awareness even at challenging layouts, roadwork sites, and along unknown roadways.
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Richard, Laura Amanda. "A study of the crystallographic, magnetic and electronic properties of selected ZrM2-H systems." Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:276c59fe-cf45-42d2-a5a0-8c534c8b46bd.
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Dissolution of hydrogen into intermetallic compounds characteristically occurs at interstitial sites, causing little alteration to the base metal substructure but often bringing about substantial electronic and magnetic changes to the material. These hydrogen-induced alterations in the intermetallic hydrides are of interest both on a fundamental research level and in terms of technological applications; however, there exists no general theory as to how and why these alterations arise. The objective of this research is to elucidate to general effect of hydrogen on intermetallic compounds through the study of crystallographic, magnetic and electronic properties. An investigation has been carried out on the properties of three intermetallic compound - hydrogen systems of general formula ZrM₂, where M = V, Cr, Mn. All three compounds reversibly absorbed hydrogen with no change in crystal symmetry: powder diffraction studies showed that hydrogen was accommodated in interstitial sites of the existing metal sublattice via lattice expansion. The measurement of the magnetic properties of these systems was combined with the determination of conductivity and dielectric properties in order to describe the electronic e¤ects of hydrogen absorption. Despite the lack of signi
cant structural alteration in these systems, electron transfer between the metal sublattice and hydrogen may occur, as manifested in the appearance/disappearance of magnetic phenomena and the increase/decrease of electrical conductivity. Whilst the hydrogen addition in ZrM₂-H occurs simply via an expansion of the crystal structure, hydrogen does not act purely as null dilutant - there exist subtle electronic changes connected with the hydriding process as well.
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Kelly, Michael Jon. "Hybrid ferrocene-based systems." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:fd46594d-98d6-4f8a-a6ab-eb5ee74ba7f3.
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This thesis explores the capacity of sterically and electronically unsaturated boranes to bind substrates of biological and environmental interest, and transduce such binding events into a photo-physical and/or electrochemical response, hence reporting the presence of these substrates. Chapter three details the synthesis of a range of novel ferrocenyl boranes featuring either a proximal hydrogen-bond donor or a second Lewis acidic centre. These novel boranes were shown to be competent at binding both cyanide and fluoride anions, with the role played by a proximal hydrogen-bond donor or a second Lewis acidic centre in anion binding investigated by both NMR and crystallographic studies. Chapter four reports the synthesis of novel pyridinyl and related boronic esters, as well as unexpected mixed alkenyl/aryl boranes. The capacity of both types of system to bind fluoride or cyanide anions in solution was investigated by UV-Vis and NMR studies. The photo-physical responses to these anions were also probed, leading to the establishment of both switch-on and switch-off fluorescent responses. Chapter five extends the knowledge derived from selective anion receptor design and combines this with recent developments in the field of frustrated Lewis pairs (FLPs) to activate, bind and report the presence of nitrous oxide (N<sub>2</sub>O) molecule. Thus, the syntheses of novel, highly Lewis acidic ferrocenyl boranes that incorporate a high degree of steric loading around the boron centre are reported. The electrochemical and photo-physical response of an FLP system to the presence of N<sub>2</sub>O was investigated leading to the development of a novel N<sub>2</sub>O reporting system.
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Samson, Akiev. "Digital human modeling for ergonomic assessment of patient lifting by paramedics." Diss., Online access via UMI:, 2009.
Find full textAbstract:
Thesis (M.S.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Science, Department of Systems Science and Industrial Engineering, 2009.<br>Includes bibliographical references.
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Ernst, Sven. "Studying the altered reactivity of electrochemical systems in room temperature ionic liquids." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:b865be7b-ed4a-4983-b407-6e4cb27aad4f.
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The work presented in this thesis examines the electrochemical behaviour of a number of species, both surface-bound and in the solution phase, in various room-temperature ionic liquids (RTILs), in order to identify systems which show altered reactivities in room-temperature ionic liquids, compared to that in conventional, molecular, aprotic solvents. The fundamentals of electrochemistry are outlined and an introduction to room-temperature ionic liquids is given, after which the results of six original investigations are presented, as follows; The electrochemical response of surface-bound anthraquinonyl films was investigated as a function of RTIL cation size. The reduction of oxygen to superoxide in the [C<sub>2</sub>mim][NTf<sub>2</sub>] RTIL was studied at different carbon electrodes. The mechanisms of electrodeposition and stripping of Zn(II) onto bulk zinc deposits, on glassy carbon electrodes, in the [C<sub>4</sub>mPyrr][NTf<sub>2</sub>] RTIL were investigated. A novel and successful method for the fabrication of zinc microdisk electrodes was developed and the electrochemical behaviour of these electrodes was investigated. The mechanisms for the electrochemical reductions of some bromo- and nitrobenzenes at platinum microelectrodes were determined in the [C<sub>4</sub>mPyrr][NTf<sub>2</sub>] ionic liquid, in order to identify systems which displayed changed reactivities in RTILs compared to those in molecular aprotic solvents. The altered reactivity of 1-bromo-4-nitrobenzene in the [C<sub>4</sub>mPyrr][NTf<sub>2</sub>] ionic liquid was utilised via electrochemical reduction at zinc microelectrodes in order to form arylzinc compounds. The work presented in this thesis shows that the oft-taken view that the reactivity of a given species in an ionic liquid will mimic that in conventional aprotic solvents is not always the case. Reactivities can be markedly different between RTILs and aprotic solvents and can also be highly dependent on the specific ionic liquid employed.
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Rodgers, Christopher T. "Magnetic field effects in chemical systems." Thesis, University of Oxford, 2007. http://ora.ox.ac.uk/objects/uuid:f5878b88-c5ba-4cbd-83af-857431aef66e.
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Magnetic fields influence the rate and/or yield of chemical reactions that proceed via spin correlated radical pair intermediates. The field of spin chemistry centres around the study of such magnetic field effects (MFEs). This thesis is particularly concerned with the effects of the weak magnetic fields B₀ ~ 1mT relevant in the ongoing debates on the mechanism by which animals sense the geomagnetic field and on the putative health effects of environmental electromagnetic fields. Relatively few previous studies have dealt with such weak magnetic fields. This thesis presents several new theoretical tools and applies them to interpret experimental measurements. Chapter 1 surveys the development and theory of spin chemistry. Chapter 2 introduces the use of Tikhonov and Maximum Entropy Regularisation methods as a new means of analysing MARY field effect data. These are applied to recover details of the diffusive motion of reacting pyrene and N,N-dimethylaniline radicals. Chapter 3 gives a fresh derivation and appraisal of an approximate, semiclassical approach to MFEs. Monte Carlo calculations allow the elucidation of several "rules of thumb" for interpreting MFE data. Chapter 4 discusses recent optically-detected zero-field EPR measurements, adapting the gamma-COMPUTE algorithm from solid state NMR for their interpretation. Chapter 5 explores the role of RF polarisation in producing MFEs. The breakdown in weak fields of the familiar rotating frame approximation is analysed. Chapter 6 reviews current knowledge and landmark experiments in the area of animal magnetoreception. The origins of the sensitivity of European robins Erithacus rubecula to the Earth’s magnetic field are given particular attention. In Chapter 7, Schulten and Ritz’s hypothesis that avian magnetoreception is founded on a radical pair mechanism (RPM) reaction is appraised through calculations in model systems. Chapter 8 introduces quantitative methods of analysing anisotropic magnetic field effects using spherical harmonics. Chapter 9 considers recent observations that European robins may sometimes be disoriented by minuscule RF fields. These are shown to be consistent with magnetoreception via a radical pair with no (effective) magnetic nuclei in one of the radicals.
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Kristen, Juliane Ute. "Amphiphilic BAB-triblock copolymers bearing fluorocarbon groups : synthesis and self-organization in aqueous media." Phd thesis, Universität Potsdam, 2011. http://opus.kobv.de/ubp/volltexte/2012/6178/.
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In this work new fluorinated and non-fluorinated mono- and bifunctional trithiocarbonates of the structure Z-C(=S)-S-R and Z-C(=S)-S-R-S-C(=S)-Z were synthesized for the use as chain transfer agents (CTAs) in the RAFT-process. All newly synthesized CTAs were tested for their efficiency to moderate the free radical polymerization process by polymerizing styrene (M3). Besides characterization of the homopolymers by GPC measurements, end- group analysis of the synthesized block copolymers via 1H-, 19F-NMR, and in some cases also UV-vis spectroscopy, were performed attaching suitable fluorinated moieties to the Z- and/or R-groups of the CTAs.
Symmetric triblock copolymers of type BAB and non-symmetric fluorine end- capped polymers were accessible using the RAFT process in just two or one polymerization step. In particular, the RAFT-process enabled the controlled polymerization of hydrophilic monomers such as N-isopropylacrylamide (NIPAM) (M1) as well as N-acryloylpyrrolidine (NAP) (M2) for the A-blocks and of the hydrophobic monomers styrene (M3), 2-fluorostyrene (M4), 3-fluorostyrene (M5), 4-fluorostyrene (M6) and 2,3,4,5,6-pentafluorostyrene (M7) for the B-blocks.
The properties of the BAB-triblock copolymers were investigated in dilute, concentrated and highly concentrated aqueous solutions using DLS, turbidimetry, 1H- and 19F-NMR, rheology, determination of the CMC, foam height- and surface tension measurements and microscopy. Furthermore, their ability to stabilize emulsions and microemulsions and the wetting behaviour of their aqueous solutions on different substrates was investigated. The behaviour of the fluorine end-functionalized polymers to form micelles was studied applying DLS measurements in diluted organic solution.
All investigated BAB-triblock copolymers were able to form micelles and show surface activity at room temperature in dilute aqueous solution. The aqueous solutions displayed moderate foam formation. With different types and concentrations of oils, the formation of emulsions could be detected using a light microscope. A boosting effect in microemulsions could not be found adding BAB-triblock copolymers. At elevated polymer concentrations, the formation of hydrogels was proved applying rheology measurements.<br>Im Rahmen dieser Arbeit wurden neue fluorierte und unfluorierte mono- und bifunktionelle Trithiocarbonate der Typen Z-C(=S)-S-R und Z-C(=S)-S-R-S-C(=S)-Z zur Anwendung als CTAs (chain- transfer agents) im RAFT-Polymerisationsverfahren hergestellt. Alle CTAs wurden erfolgreich auf ihre Effizienz zur Steuerung des radikalischen Polymerisationsverfahrens hin durch Polymerisation von Styrol (M3) getestet. Neben GPC-Messungen wurden Endgruppenanalysen der synthetisierten Blockcopolymere mittels 1H-, 19F-NMR und in manchen Fällen auch UV-Vis Spektroskopie durchgeführt. Dazu wurden die Z- und/oder R-Gruppen der CTAs mit geeigneten fluorierten Gruppen versehen.
Durch Anwendung des RAFT Verfahrens konnten symmetrische Triblockcopolymere vom Typ BAB bzw. mit einer Fluoralkylgruppe endgecappte unsymmetrische Polymere in nur zwei bzw. einem Polymerisationsschritt hergestellt werden. Das RAFT- Polymerisationsverfahren ermöglicht sowohl die Polymerisation hydrophiler Monomere wie N-Isopropylacrylamid (NIPAM) (M1) oder N-Acryloylpyrrolidin (NAP) (M2) für die A-Blöcke als auch der hydropoben Monomere Styrol (M3), 2-Fluorostyrol (M4), 3-Fluorostyrol (M5), 4- Fluorostyrol (M6) und 2,3,4,5,6- Pentafluorostyrol (M7) für die B-Blöcke.
Die Eigenschaften der Blockcopolymere in verdünnten, konzentrierten und hochkonzentrierten wässrigen Lösungen wurden mittels DLS, Trübungsphotometrie, 1H- und 19F-NMR, Rheologie, CMC- sowie Schaumhöhen- und Oberflächenspannungsmessungen und Lichtmikroskopie untersucht. Weiterhin wurden ihre Eigenschaften als Emulgatoren und in Mikroemulsion untersucht. Das Micellbildungsverhalten der hydrophob endfunktionalisierten Polymere wurde mittels DLS Messungen in verdünnter organischer Lösung untersucht.
Alle untersuchten BAB-Triblöcke bildeten Micellen und zeigten Oberflächenaktivität bei Raumtemperatur in verdünnter, wässriger Lösung. Weiterhin zeigen die wässrigen Lösungen der Polymere mäßige Schaumbildung. Mit verschiedenen Öltypen und Ölkonzentrationen wurden Emulsionen bzw. Mikroemulsionen gebildet. In Mikroemulsion wurde durch Zugabe von BAB-Triblockopolymeren kein Boosting-Effekt erzielt werden. Bei Untersuchung höherer Polymerkonzentrationen wurde die Bildung von Hydrogelen mittels rheologischer Messungen nachgewiesen. Verschiedene Substrate konnten benetzt werden. Die hydrophob endgecappten Polymere bilden in verdünnter organischer Lösung Micellen, die mittels DLS untersucht wurden, und zeigen somit Tensidverhalten in nichtwässriger Lösung.
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Seel, Andrew G. "Incoherent neutron scattering studies of select inorganic systems : I. Nuclear momentum measurements of multiple masses, II. The dynamics of coordinated ammonia in zeolite A." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:48e7a487-b203-46d6-9bb3-2866b1d98f1b.
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Spectroscopic measurements are detailed within this thesis, utilising incoherent neutron scattering to examine the dynamics of various condensed-matter systems, from nanosecond to sub-femtosecond timescales. The body of this work is divided into two distinct areas of research. I. Nuclear Momentum Measurements of Multiple Masses Deep inelastic neutron scattering (DINS) is used to probe the nuclear momentum distributions and kinetic energies of individual atomic species in sodium hydride (both in bulk and as nanoparticulates within a silica matrix), enriched lithium-7 fluoride and lithium tetra-ammoniate. Extension of DINS to examine heavier (M>4amu) nuclei is detailed, accomplished by the application of a simple stoichiometric fixing technique within the standard DINS theory and analysis protocols. The validity and accuracy of such simultaneous measurements are discussed. II. The Dynamics of Coordinated Ammonia in Zeolite A Inelastic neutron scattering (INS) and quasielastic neutron scattering (QENS) are utilised in the examination of vibrational and stochastic dynamics of the ammonia molecule, as coordinated to the internal surface of a zeolite host. Both sodium and copper-exchanged forms of zeolite-A are studied, with proton-weighted, low energy phonon-modes and rotational processes being observed and assigned.
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Shirvani, Tara. "The role of catalysts and algae in forming a sustainable solution for a global food and fuel crisis." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:30af0957-1ed6-4ea7-949b-f120606ab22e.
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This thesis undertakes three separate lifecycle analyses to determine the emissions and fossil energy demand required to process algae biomass into renewable fuel and animal feed. A complete well-to-wheel fuel-cycle analysis is conducted for the production of biodiesel and jet biofuel from algae biomass. The environmental impacts of algae-based fuels for the road transportation and aviation industry are benchmarked against analogue conventional fossil fuels. This thesis demonstrates that algae biofuel production can only realize its inherent environmental advantage of reduced GHG emissions, once every step of the production chain is fully optimized and decarbonized. This includes smart co-product utilization, offsetting fertilizers through wastewater recycling, reusing exhaust gases as additional CO2 source and using decarbonized electricity, heat and indirect energy. The definition of a Catalyst Sensitivity Index (CSI) demonstrates how catalytic efficiency increases can impact the fossil energy consumption and the greenhouse gas emissions balance of catalyst-dependent processes. The CSI will allow the industry to highlight 'best practice catalysts' and draw conclusions for what efficiency gains one could anticipate with higher performance catalysts. For countries where a decarbonized electricity and heat grid is not available to guarantee low-carbon algae fuel production and the looming resource scarcity around marine feed production has become more pressing, the alternative use of algae for aquafeed production is recommended. This thesis analyses major routes towards the future cost-competitive production of microbial biomass as sustainable fish meal and oil source to meet a global demand for depleting fish feed supplies. A comprehensive economic cost analysis and lifecycle assessment demonstrates the feasibility of replacing global fish meal and fish oil supplies with low-carbon and affordable algae feed by the year 2030. This research reveals how algae feed production has the potential to transform a pressing resource tipping point into a turning point.
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Cherry, Shirley J. "Radiographic Pathology of the Skeletal System." Digital Commons @ East Tennessee State University, 2010. https://dc.etsu.edu/etsu-works/2481.
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Medal, Diana Steed. "Distance instruction in medical terminology for occupational therapy students in Yokkaichi, Mie, Japan." CSUSB ScholarWorks, 2001. https://scholarworks.lib.csusb.edu/etd-project/1999.
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Sharma, Satyajeet. "AMORPHOUS PHASE FORMATION IN MECHANICALLY ALLOYED FE-BASED SYSTEMS." Doctoral diss., University of Central Florida, 2008. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2484.
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ABSTRACT Bulk metallic glasses have interesting combination of physical, chemical, mechanical, and magnetic properties which make them attractive for a variety of applications. Consequently there has been a lot of interest in understanding the structure and properties of these materials. More varied applications can be sought if one understands the reasons for glass formation and the methods to control them. The glass-forming ability (GFA) of alloys can be substantially increased by a proper selection of alloying elements and the chemical composition of the alloy. High GFA will enable in obtaining large section thickness of amorphous alloys. Ability to produce glassy alloys in larger section thicknesses enables exploitation of these advanced materials for a variety of different applications. The technique of mechanical alloying (MA) is a powerful non-equilibrium processing technique and is known to produce glassy (or amorphous) alloys in several alloy systems. Metallic amorphous alloys have been produced by MA starting from either blended elemental metal powders or pre-alloyed powders. Subsequently, these amorphous alloy powders could be consolidated to full density in the temperature range between the glass transition and crystallization temperatures, where the amorphous phase has a very low viscosity. This Dissertation focuses on identifying the various Fe-based multicomponent alloy systems that can be amorphized using the MA technique, studying the GFA of alloys with emphasis on improving it, and also on analyzing the effect of extended milling time on the constitution of the amorphous alloy powder produced at earlier times. The Dissertation contains seven chapters, where the lead chapter deals with the background, history and introduction to bulk metallic glasses. The following four chapters are the published/to be published work, where the criterion for predicting glass formation, effect of Niobium addition on glass-forming ability (GFA), lattice contraction on amorphization, effect of Carbon addition on GFA, and observation of mechanical crystallization in Fe-based systems have been discussed. The subsequent chapter briefly mentions about the consolidation of amorphous powders and presents results of hot pressing and spark plasma sintering on one of the alloy systems. The final chapter summarizes the Dissertation and suggests some prospective research work that can be taken up in future. The Dissertation emphasizes the glass-forming ability, i.e., the ease with which amorphization can occur. In this work the milling time required for amorphization was the indicator/measure of GFA. Although the ultimate aim of this work was to consolidate the Fe-based amorphous alloy powders into bulk so as to undertake mechanical characterization, however, it was first necessary to study the glass forming aspect in the different alloy systems. By doing this a stage has been reached, where different options are available with respect to amorphous phase-forming compositions and the knowledge to improve glass-forming ability via the mechanical alloying technique. This will be ultimately useful in the powder compaction process into various shapes and sizes at optimum pressure and temperature. The study on mechanical crystallization indicates, or in a way defines, a limit to the process of amorphization, and it was also demonstrated that this phenomenon is more common in occurrence than and not as restricted as it was earlier reported to be.<br>Ph.D.<br>Department of Mechanical, Materials and Aerospace Engineering<br>Engineering and Computer Science<br>Materials Science & Engr PhD
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Patil, Umesh. "STRUCTURAL EVOLUTION IN MECHANICALLY ALLOYED FE-BASED POWDER SYSTEMS." Master's thesis, University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3528.
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A systematic study of iron-based binary and multi-component alloys was undertaken to study the structural evolution in these powders as a function of milling time during mechanical alloying. Blended elemental powders of Fe100-XBX (where x = 5, 10, 17, 20, 22, 25, 37.5 and 50 at. %) and a bulk metallic glass (BMG) composition (Fe60Co8Zr10Mo5W2B15) were subjected to mechanical alloying in a SPEX 8000 mixer mill. X-ray diffraction technique was employed to study the phase evolution, crystallite size, lattice strain and also to determine the crystal structure(s) of the phases. Depending on the milling time, formation of supersaturated solid solutions, intermetallics, and amorphous phases was noted in the binary Fe-B powder mixtures. A maximum of about 22 at. % B was found to dissolve in Fe in the solid state, and formation of FeB and Fe2B intermetallics was noted in some of the powder blends. However, an interesting observation that was made, for the first time, related to the formation of a crystalline phase on continued milling of the amorphous powder in the BMG composition. This phenomenon, termed mechanical crystallization, has been explored. Reasons for the mechanical crystallization of the amorphous powder using the X-ray diffraction and electron microscopy methods have been discussed. External heat treatments of the milled powder were also conducted to study the complete crystallization behavior of the amorphous phase. Preliminary attempts were made to consolidate the milled BMG powder to bulk shape by hot isostatic pressing (HIP) and magnetic compaction techniques. Full densification was not achieved. Nanoindentation and microhardness tests were performed to characterize the mechanical properties of the glassy alloy. Nanoindentation results gave an elastic modulus of 59 GPa, lower than the expected value of 184 GPa; due to the presence of porosity in the consolidated sample. Optimization of the consolidation parameters is required to achieve a fully dense material.<br>M.S.<br>Department of Mechanical, Materials and Aerospace Engineering;<br>Engineering and Computer Science<br>Materials Science and Engineering
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McGregor, Rodney. "Introduction of a Sonographer Practitioner Role in the Australian Health Care System: Opportunities and Barriers." Thesis, The University of Sydney, 2014. http://hdl.handle.net/2123/10136.
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In Australia, the majority of sonographers produce an informal report describing the ultrasound findings and a medical practitioner then translates this informal report into the final ultrasound report. This thesis will review the professional role of Australian sonographers and examine sonographer views on formally extending their role to include full responsibility for both the ultrasound examination and completion of the final written report. In sonography, this role extension has been given the title of sonographer practitioner. The research employed a mixed-method research design incorporating quantitative and qualitative methods. A survey of members of the Australian Sonographers Association consisted of closed-ended questions that provided demographic data, type and location of workplace and views concerning sonographer practitioner development. Complementing the closed-ended questions, three opened-ended questions sought information about what would encourage or discourage sonographers from being involved in some form of role extension and the opportunity to comment on sonographer practitioner issues. The themes and concepts identified in the qualitative component of the survey were then explored, in greater depth, with a small sample of survey respondents who agreed to participate in a follow-up individual semi-structured interview. Results from the survey revealed that a majority of respondents (82%) thought there is a need to extend sonographer career pathways. Respondents indicated they were in favour of sonographer practitioner development, and a majority (66%) also indicated they would consider becoming a sonographer practitioner. Analysis of the opened-ended survey questions found the most commonly described incentives or motivations for sonographer practitioner development were professional recognition, remuneration and increased knowledge. Conversely, the most commonly perceived barriers were legal issues, insurance and further study. The survey and subsequent interviews revealed a range of opinions and views as to what duties would constitute a sonographer practitioner role, ranging from reporting on ultrasound studies to undertaking interventional studies. The interviews revealed that some sonographers were already performing in extended roles, including reporting on ultrasound examinations, in a variety of working environments, although this role is not formally recognised within the Australian health care system. Formal recognition of a sonographer practitioner role would offer an extended career pathway to sonographers and work to minimise litigation risks of sonographers working in extended roles now and in the future.
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Kaunnil, Anuchart. "Development and evaluation of occupational therapy-Mahidol Clinic System (OT-MCS) for post-stroke rehabiliation in Thailand." Thesis, Northumbria University, 2013. http://nrl.northumbria.ac.uk/11778/.
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In 2011 it was estimated that in Thailand there were 498,800 stroke survivors of both sexes but most were over the age of 65. They were served by only 625 occupational therapists (OTs). Occupational therapy (OT) plays a key role in the rehabilitation service for stroke patients, in particular, by enabling stroke survivors to reengage with activities of daily living and to resume work or family tasks. OT needs to be culturally appropriate and relevant to the therapists, stroke patients and their families. The Occupational Therapy Mahidol Clinic System (OT-MCS) has been designed to be culturally relevant and is based on collaborative teamwork which can better address the needs of the stroke patients. OT-MCS was introduced in 6 regional OT clinics. This study compared perceptions of stroke clients who took part in the new approach 8 weeks before and during the rehabilitation. One hundred and twenty stroke participants were divided into 2 functional groups (slow and fast stream rehabilitation). Stroke participants (N=120) and OTs (N=60) explored the arrangement of activity items into domains for creating a new activity card sort (ACS). Sixty stroke participants (slow stream rehabilitation) and 60 OTs were surveyed to investigate the attitudes of “satisfaction” and “importance” via 40 therapeutic activities. Sixty stroke participants (fast stream rehabilitation) evaluated the levels of their activity engagement in diverse cultural-therapeutic activities. Lastly, 23 stroke participants (slow and fast stream rehabilitation) were interviewed in order to ascertain their lived experiences after the use of OT-MCS and the data were analysed using thematic analysis. The integrated analysis demonstrated strong satisfaction and engagement with OT-MCS. The use of the activity catalogue met with positive attitudes from the stroke participants and in particular the collaborative approach of OTs and participants gave meaning to the activities and a sense of self management. In addition in the fast stream rehabilitation participants reported satisfaction with the transferability of the activities to the home and external environment and their relevance to supporting family life. The OT-MCS for Thai stroke rehabilitation is a comprehensive OT service, which improves the perception of benefit in stroke clients enabling them to perform meaningful and purposeful activities based on their local and regional lifestyles. This culturally appropriate approach helps stroke clients to re-develop their life-skills. Through the use of meaningful and relevant activities which meet their specific needs, stroke clients can lead more satisfying and fulfilling lives.
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Stevens, J. P. "The meiotic and breeding systems of Allium schoenoprasum L. in natural populations." Thesis, University of York, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.356844.
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Harrison, Nicholas. "Equal channel angular pressing of elemental & alloyed P/M aluminium systems." Thesis, University of Birmingham, 2014. http://etheses.bham.ac.uk//id/eprint/5063/.
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Aluminium powder metallurgy provides lightweight automobile components for reduced energy consumption. Conventional press-and-sinter methods can leave porosity in final parts, which reduces strength of the alloy. Equal Channel Angular Pressing (ECAP) can be used to increase density of powder compacts after sintering via severe plastic deformation. Solid state sintering of pure aluminium and liquid phase sintering of a commercial Al-Sn bearing alloy were analysed with industrial collaborative support. The use of room temperature ECAP to these sintered materials was investigated. Cold compaction produced a porous region on the outside of all samples due to increased friction at the die wall. The application of ECAP to pure aluminium and bearing alloys caused elongation in the longitudinal section and a relatively equiaxed microstructure in the transverse section. Sintering at 500°C for 1 and lOhours and 550°C for lh was ineffective as liquid tin did not wet the aluminium effectively. After ECAP, density and hardness increased with refined grain sizes and formed two distinct regions; a denser, deformed core and a non-deformed skin, which resulted from non-uniform densification after cold compaction.
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ROSENBLATT, THOMAS. "Structures uniaxiales p(nx1) dans le systeme pb/cu(110) : etude par simulation des phases non alliees et alliees." Paris 6, 1996. http://www.theses.fr/1996PA066365.
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On presente une etude de simulation de la serie des structures uniaxiales p(nx1), avec n=4, 17, 13, 9, 14, 19, 5, des couches bidimensionnelles de plomb sur un substrat (110) de cuivre, aux taux de recouvrement proches de la monocouche. Ces structures ont ete mises en evidence anterieurement par differentes techniques experimentales. Nous avons etudie les structures non alliees et alliees par deux techniques de simulation: relaxation statique, (minimisation de forces interatomiques au zero absolu) et simulation monte carlo a temperatures elevees. Des potentiels de paires et des potentiels a n corps du type liaison forte ont ete employes. Les configurations d'energie potentielle minimale des structures non alliees p(4x1) et p(5x1) ont ete determinees par relaxation statique. L'isotherme d'adsorption, taux de recouvrement versus pression d'etalement, a la temperature du zero absolu a ete calculee pour les structures p(nx1) non alliees a l'aide d'un modele issu du modele de frenkel-kontorova. Ces calculs n'ont pas permis de demontrer la stabilite meme relative des structures intermediaires a la p(4x1) et la p(5x1). Un essai de calcul de l'energie libre de ces memes structures a temperatures superieures au zero absolu par une integration thermodynamique, n'a pas change les conclusions des etudes a 0 k. Dans une derniere partie, les structures d'equilibre de la couche de plomb sur la face (110) du cuivre, determinees par le calcul des bilans d'energie potentielle accompagnant la transformation des couches non alliees en alliages de surface, ont permis d'etablir la stabilite de phases alliees a bas et a haut taux de recouvrement, en accord avec des resultats experimentaux recents
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Dommisse, Elvira M. "Development of an Agrobacterium transformation system for onion (Allium cepa L.)." Thesis, University of Canterbury. Botany, 1993. http://hdl.handle.net/10092/5674.
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Onion (Allium cepa) bulbs of the New Zealand-bred cultivars 'Pukekohe Longkeeper' and 'Early Longkeeper' produced tumourous growths after inoculation with 25 virulent strains of Agrobactenum tumefaciens, A. rubi and A. rhizogenes. The majority of these tumours produced nopaline, indicating that tumour cells were transformed. Some excised tumours produced roots in sterile culture.
Eight onion genotypes were screened in tissue culture for callus formation, regeneration of plantlets from callus and clonal multiplication by shoot proliferation. All genotypes could be clonally multiplied and four were readily regenerable from callus. A technique for plantlet multiplication, which uses longitudinally-bisected stems of in vitro-germinated onion seedlings as explants, was developed. Onion (‘Pukekohe Longkeeper', 'Southport White Globe', 'Japanese Saporo Yellow' and 'Hikeeper Fl ') protoplasts were isolated and cultured on a range of media. These protoplasts formed new cell walls and sometimes divided, but only first divisions were regularly seen.
Kanamycin, geneticin (G418), hygromycin and chlorsulfuron were evaluated for their use as selective agents in onion transformation experiments. Tissues surveyed for sensitivity to these selective agents included seeds and seedlings on germination and callusing media, established callus on callusing and regeneration media, and shoot cultures on shoot proliferation medium. Hygromycin was shown to be the antibiotic most toxic to tissues of all the surveyed onion cultivars, with effects being obvious
in all tissues after 4-5 weeks of culture on concentrations as low as 20 mgl-1. Kanamycin was shown to be the least toxic of the selection agents surveyed. The kanamycin analogue G418 was considerably more toxic to most onion cultures than kanamycin. However, responses of cultures to G418 were slower than those to hygromycin. The herbicide chlorsulfuron was also shown to be toxic to onion seedlings and shoot cultures.
The ability of Agrobacterium tumefaciens to transfer foreign genes to A. cepa was demonstrated. A single, putatively transformed plantlet (RC1), was regenerated from an onion seedling stem via callus, following co-cultivation of stem explants with Agrobacterium strain LBA4404 harbouring the binary vector pKIWI110. In addition, 41 auxiliary or adventitious shoots which grew directly from basal plates injected in vitro with four strains of A. tumefaciens (each harbouring the binary vectors pKIWI110 or pGA643) exhibited resistance to G418 in culture. The binary vectors used carry the neomycin phosphotransferase II gene (nptII) controlled by the nopaline synthase (nos) promoter. Both RC1 and some of the shoots growing from basal plate explants produced roots when grown on culture media supplemented with G418. Southern analyses showed that fragments of DNA from RC1 and from five of the 41 G418-resistant shoots hybridized to a 1.25 kbp nptII probe. (β- glucuronidase (GUS) activity was detected in over half of the plantlets derived from basal plate tissue injected with A. tumefaciens strains LBA4404 or C58, both of which harboured pKIWI110. Molecular and phenotypic evidence suggested that the putatively transformed plants produced from injected basal plate tissues were
chimeric.
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Flassig, Robert Johann. "Dusty ringlets in Saturn’s ring system." Master's thesis, Universität Potsdam, 2008. http://opus.kobv.de/ubp/volltexte/2008/2704/.
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Recently, several faint ringlets in the Saturnian ring system were found to maintain a peculiar orientation relative to Sun. The Encke gap ringlets as well as the ringlet in the outer rift of the Cassini division were found to have distinct spatial displacements of several tens of kilometers away from Saturn towards Sun, referred to as heliotropicity (Hedman et al., 2007). This is quite exceptional, since dynamically one would expect eccentric features in the Saturnian rings to precess around Saturn over periods of months.
In our study we address this exceptional behavior by investigating the dynamics of circumplanetary dust particles with sizes in the range of 1-100 µm. These small particles are perturbed by non-gravitational forces, in particular, solar radiation pres- sure, Lorentz force, and planetary oblateness, on time-scales of the order of days. The combined influences of these forces cause periodical evolutions of grains’ orbital ec- centricities as well as precession of their pericenters, which can be shown by secular perturbation theory. We show that this interaction results in a stationary eccentric ringlet, oriented with its apocenter towards the Sun, which is consistent with obser- vational findings.
By applying this heliotropic dynamics to the central Encke gap ringlet, we can give a limit for the expected smallest grain size in the ringlet of about 8.7 microns, and constrain the minimal lifetime to lie in the order of months. Furthermore, our model matches fairly well the observed ringlet eccentricity in the Encke gap, which supports recent estimates on the size distribution of the ringlet material (Hedman et al., 2007).
The ringlet-width however, that results from our modeling based on heliotropic dynamics, slightly overestimates the observed confined ringlet-width by a factor of 3 to 10, depending on the width-measure being used. This is indicative for mechanisms, not included in the heliotropic model, which potentially confine the ringlet to its observed width, including shepherding and scattering by embedded moonlets in the ringlet region.
Based on these results, early investigations (Cuzzi et al., 1984, Spahn and Wiebicke, 1989, Spahn and Sponholz, 1989), and recent work that has been published on the F ring (Murray et al., 2008) - to which the Encke gap ringlets are found to share similar morphological structures - we model the maintenance of the central ringlet by embedded moonlets. These moonlets, believed to have sizes of hundreds of meters across, release material into space, which is eroded by micrometeoroid bombardment (Divine, 1993).
We further argue that Pan - one of Saturn’s moons, which shares its orbit with the central ringlet of the Encke gap - is a rather weak source of ringlet material that efficiently confines the ringlet sources (moonlets) to move on horseshoe-like orbits. Moreover, we suppose that most of the narrow heliotropic ringlets are fed by a moonlet population, which is held together by the largest member to move on horseshoe-like orbits. Modeling the equilibrium between particle source and sinks with a primitive balance equation based on photometric observations (Porco et al., 2005), we find the minimal effective source mass of the order of 3 · 10-2MPan, which is needed to keep the central ringlet from disappearing.<br>Im Sommer 2004 erreichte die Raumsonde Cassini Saturn, den zweitgrößten Planeten in unserem Sonnensystem. Seitdem wurden fantastische Entdeckungen von einer über 250 Wissenschaftler umfassenden internationalen Gemeinschaft gemacht, deren physikalische Erklärungen unser Verständnis der Welt enorm erweitert haben.
Die Saturnringe, welche aus losem, zumeist eisigem Staubmaterial bestehen, bieten außergewöhnlich viele Strukturen, welche räumlich und zeitlich mehr oder weniger stark variieren. Diese Eigenschaft resultiert aus einer Unzahl an zusätzlichen Kräften, welche die allgemein bekannte Kepler-Bewegung beeinflussen. So befinden sich mehrere Lücken, oder auch Teilungen, in den Ringen, welche schon in Voyager 1/2 Daten Anfang der achtziger Jahre gesehen wurden. Diese werden teilweise durch Resonanzen der Saturn Monde (z.B. innere Ringkante der Cassini Teilung und Mimas), aber auch durch Monde an sich (z.B. Keeler Teilung und Daphnis, Encke Teilung und Pan) über gravitative Wechselwirkungen erzeugt.
In diesen Ringteilungen befindet sich - mit Ausnahme von dem ein oder anderen feinen Staub-Ringlein - kein Material. Hedman et al. (2007) haben eine interessante Entdeckung gemacht. Einige dieser feinen Staub-Ringlein sind exzentrisch und halten eine besondere Orientierung zur Sonne aufrecht. Genauer, ihr Apozentrum ist in Richtung Sonne gerichtet, weshalb sie heliotropische Ringlein getauft wurden.
Für exzentrische Strukturen im Saturnsystem ist diese eingefrorene Orientierung ungewöhnlich. Normalerweise würde eine Präzession von exzentrischen Strukturen um Saturn auf einer Zeitskala von Monaten, deren Rate im Wesentlichen durch die Abplattung von Saturn bestimmt ist, erwartet werden.
In dieser Diplomarbeit untersuchen und erklären wir das außergewöhnlich heliotropische Verhalten qualitativ, sowie quantitativ mit Hilfe von Orbit gemittelten Störungsgleichungen. Dabei demonstrieren wir, dass ein Zusammenspiel von drei Störungskräften (Strahlungsdruck der Sonne, Abplattung der Pole vom Saturn, Lorentzkraft) periodisch gekoppelte Variationen von Orbitexzentrizität und Position des Perizentrums erzeugen, und im Ensembel einen exzentrischen Ring hervorbringen, dessen Apozentrum in Richtung Sonne zeigt.
Mit diesem Modell können wir gemessene Ringleinexzentrizitäten und -breiten in der Encke Teilung (Ferrari and Brahic, 1997, Hedman et al., 2007), unter Annahme gängiger Größenverteilungen (Divine, 1993, Krivov et al., 2003), sehr gut bzw. befriedigend reproduzieren. Die Ringleinbreiten werden um den Faktor 3 bis 10 überschätzt, was auf zusätzliche, nicht berücksichtigte Wechselwirkungen schließen läßt. Hier seien Teilchenstreunung an möglichen Moonlets (kleinere Monde) im Ringlein und Wechselwirkungen zwischen den Staubteilchen als zwei mögliche Ursachen genannt. Aufbauend auf dieser heliotropischen Dynamik können wir eine untere Grenze der Staubgrößenverteilung in der Encke Teilung ableiten, welche in eine Mindestlebenszeit für heliotropisches Ringleinmaterial übersetzt werden kann.
Motiviert durch die leicht überschätzen Ringleinbreiten, azimuthal unregelmäßigen Helligkeitsschwankungen (z.B. Ferrari and Brahic, 1997), früheren (Cuzzi et al., 1984, Spahn and Wiebicke, 1989, Spahn and Sponholz, 1989) und aktuellen Arbeiten (Murray et al., 2008), sowie der evidenten knickrigen Struktur des zentralen Encke Ringleins (siehe Titelbild, linke Seite), wenden wir zur Materialgenerierung das sog. Impact-Eject Szenario (Divine, 1993, Krüger et al., 1999) auf Moonlets an, welche an mit Sicherheit grenzender Wahrscheinlichkeit in dem Ringlein eingebettet sind.
Damit können wir ein einfaches kinetisches Modell basierend auf gemessenen Daten von Cassini (optische Tiefen, Porco et al., 2005) entwerfen. Jenes liefert, bei gegebener effektiver Lebenszeit der Teilchen im Ringlein in der Encke Teilung, eine dazu mindest nötige Quellmasse. Dabei räsonieren wir, dass Pan, welcher seine Bahn mit dem zentralen Ringlein der Encke Teilung teilt, eine untergeordnete Rolle als Materiallieferant spielt, und bestätigen somit die bisherigen Vermutungen von eingebetteten Moonlets im zentralen Ringlein der Encke Teilung. Jedoch zwingt Pan die als Materialquellen fungierenden Moonlets auf “Hufeisenbahnen”, was so das Ringlein radial begrenzt.
Des Weiteren vermuten wir, dass ein Großteil der Staubringlein auf diese Weise in einer stationären Balance zwischen Mikrometeoriten Erosion als Quelle und dynamischen Verlusten gehalten werden, welche erst durch die Existenz einer Moonlet-Population ermöglicht wird. Die Abschätzung der minimal nötigen Quellmasse liefert einen weiteren wichtigen Schritt in Richtung Antwort zu der Frage, in welcher Beziehung kleinere Monde wie Pan zu den sie umgebenden Ringlein stehen.
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Robertson, Patricia E., Rebekah J. Byrd, and Janna L. Scarborough. "Allies for All: Competencies for Working with LGBTQ Individuals Throughout the Lifespan." Digital Commons @ East Tennessee State University, 2012. https://dc.etsu.edu/etsu-works/906.
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Although core counseling processes are necessary for working with LGBTQ individuals, they are not sufficient. Given unique concerns, needs, and experiences across the lifespan, specialized awareness, knowledge and skills are needed for effective counseling service delivery for this diverse population. Awareness of personal and societal values as well as homoprejudice will be explored. Sexual and gender identity models, ethical and systemic issues, and unique LGBTQ concerns (including within group diversity) will be discussed. Through various activities, emphasis will be on skill development of appropriate counseling and systemic intervention strategies with respect to various counselor work settings (schools, agencies, higher education).
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Hellenbach, Michael. "Justice or truth? : alleged offenders with intellectual disabilities in the criminal justice system." Thesis, University of Chester, 2011. http://hdl.handle.net/10034/312148.
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This PhD study examines how people who are intellectually impaired are processed within the criminal justice system. In this context it analyses the understanding of intellectual disabilities, criminal justice decision-making processes, and the constructon of crime and punishment by professionals involved in criminal justice. Despite significant changes in mental health legislation and greater awareness by professionals of issues around intellectually disabled offenders, previous research has demonstrated that this population remains disadvantaged when coming into contact with the criminal justice system. The study focuses on how the criminal justice system maintains its traditional way of operating when engaging with people who are impaired in their intellectual capacities and who, therefore, often have difficulties in processing information and understanding complex situations. The study draws on qualitative data generated through thirty five unstructured interviews with custody sergeants, forensic examiners, prosecutors, magistrates, judges and probation officers from three regions in the North West of England: Cheshire, Merseyside and Greater Manchester. Through those interviews, the provision of support to alleged offenders is examined and the process of legal representation evaluated. By analysing decision-making processes around vulnerable defendants, two conflicting views that influence cimrinal justice professionals in their strategic behaviour were identified: protecting offenders' rights and protecting the public from criminal behaviour. It is argued that the criminal justice system draws its normative and enforcement powers from a 'discourse of truth' that concentrates on capacity and intent. Defendants who are classified as vulnerable because of impaired intellectual functioning whereby capacity to reason and intellectual disability are functionally separated. This way, an alleged offender's vulnerability becomes a manageable object within the criminal justice system and is integrated into a person's risk management. The disjointed discourse around intellectual disabilities increases the risk that people with an impaired level of intellectual functioning become drawn into the mainstream criminal justice system and, therefore, further compromises the empowerment and social inclusion of this population.
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Srisukkham, Worawut. "An intelligent decision support system for acute lymphoblastic leukaemia detection." Thesis, Northumbria University, 2017. http://nrl.northumbria.ac.uk/36140/.
Full textAbstract:
The morphological analysis of blood smear slides by haematologists or haematopathologists is one of the diagnostic procedures available to evaluate the presence of acute leukaemia. This operation is a complex and costly process, and often lacks standardized accuracy owing to a variety of factors, including insufficient expertise and operator fatigue. This research proposes an intelligent decision support system for automatic detection of acute lymphoblastic leukaemia (ALL) using microscopic blood smear images to overcome the above barrier. The work has four main key stages. (1) Firstly, a modified marker-controlled watershed algorithm integrated with the morphological operations is proposed for the segmentation of the membrane of the lymphocyte and lymphoblast cell images. The aim of this stage is to isolate a lymphocyte/lymphoblast cell membrane from touching and overlapping of red blood cells, platelets and artefacts of the microscopic peripheral blood smear sub-images. (2) Secondly, a novel clustering algorithm with stimulating discriminant measure (SDM) of both within- and between-cluster scatter variances is proposed to produce robust segmentation of the nucleus and cytoplasm of lymphocytic cell membranes. The SDM measures are used in conjunction with Genetic Algorithm for the clustering of nucleus, cytoplasm, and background regions. (3) Thirdly, a total of eighty features consisting of shape, texture, and colour information from the nucleus and cytoplasm of the identified lymphocyte/lymphoblast images are extracted. (4) Finally, the proposed feature optimisation algorithm, namely a variant of Bare-Bones Particle Swarm Optimisation (BBPSO), is presented to identify the most significant discriminative characteristics of the nucleus and cytoplasm segmented by the SDM-based clustering algorithm. The proposed BBPSO variant algorithm incorporates Cuckoo Search, Dragonfly Algorithm, BBPSO, and local and global random walk operations of uniform combination, and Lévy flights to diversify the search and mitigate the premature convergence problem of the conventional BBPSO. In addition, it also employs subswarm concepts, self-adaptive parameters, and convergence degree monitoring mechanisms to enable fast convergence. The optimal feature subsets identified by the proposed algorithm are subsequently used for ALL detection and classification. The proposed system achieves the highest classification accuracy of 96.04% and significantly outperforms related meta-heuristic search methods and related research for ALL detection.
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Bettenay, Karen. "An evaluation of pharmacist and physiotherapist prescribing trials in Queensland." Thesis, Queensland University of Technology, 2020. https://eprints.qut.edu.au/201955/1/Karen_Bettenay_Thesis.pdf.
Full textAbstract:
Whilst prescribing has traditionally been the remit of medical practitioners, there is evidence to suggest that extending prescribing rights to other health professions will benefit patients. This research evaluated the implementation, performance, and acceptability of novel pharmacist and physiotherapist prescribing initiatives across multiple Queensland Health facilities. Prescribing was perceived to be safe, effective, and improve patient access to services. Healthcare teams were supportive of the initiatives and receptive to the further development of allied health prescribing in Australia. Operational and professional barriers were identified, and these will inform the design of future non-medical prescribing implementation and evaluation frameworks.
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Tessem, Filip. "Luftmakt i multilaterala, fredsframtvingande insatser : En teoriprövande fallstudie av John. A. Wardens ”The Enemy as a System” mot Operation Allied Force & Operation Unified Protector." Thesis, Försvarshögskolan, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:fhs:diva-9164.
Full textAbstract:
John A. Warden's airpower theory, The Enemy as a System, has had a major influence on the strategic discourse ever since the foundation of this normative framework was presented in The Air Campaign in 1988. Warden’s theoretical impact was reinforced by the American successes during the Gulf War, but since then, little research has tested the theory outside the context of conventional wars of aggression. This study analyzes The Enemy as System against a peace enforcing context, characterized by multilateral cooperation. It also identifies intermediate variables that help explain why the theory is strengthened or weakened in relation to this particular context. Through qualitative methods, Operation Allied Force and Operation Unified Protector are analyzed against operational indicators within the central concepts of the five-ring model and parallel attacks. The results of the study show that NATO did not use airpower in accordance with Warden's normative theory in either of the examined operations. The absence of operational indicators could hypothetically explain why NATO failed to produce strategic effects within the operational time limits, although this remains a speculative conclusion. The result instead suggests a number of intermediate variables, such as political disagreement and strategic dissonance, which combined reduced the possibility of using airpower in accordance with Warden's theory. In addition, the fear of civilian casualties and the risk of exacerbating the post-war humanitarian situation, further reduced the possibility of attacking targets within certain subsystems of the five-ring model. The conclusion is therefore that Warden’s theoretical applicability, and thus universal validity, is weakened within the examined context.
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Mohammed, Nabaz. "Investigating the behavior of alluvial systems, thanks to the classical, isotopic and emerging tracers : case study of the alluvial aquifer of the Allier River (Auvergne, France)." Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0033/document.
Full textAbstract:
L’objectif de la thèse vise à déterminer les facteurs et processus qui contrôlent l’origine et la qualité des eaux souterraines alluviales et ainsi à mieux comprendre le fonctionnement et la vulnérabilité des aquifères alluviaux qui occupent une place prééminente dans le paysage hydrogéologique mondial tant pour leur rôle économique - production d'eau potable, développement agricole - que pour leur rôle écologique. Des mesures hydrodynamiques, hydrochimiques (ions majeurs, traces, molécules phytosanitaires et pharmaceutiques) combinées à des déterminations isotopiques (oxygène-18, deuterium, carbone-13) ont ainsi été effectuées sur 19 points incluant puits, piézomètres et eaux de surface, de février 2011 à novembre 2012, afin d’évaluer l’origine et la qualité de l’eau souterraine dans l’aquifère alluvial de la rivière Allier, un des principaux tributaires de la Loire. La zone d’étude, située près de la ville de Clermont-Ferrand (France), joue par ailleurs un rôle socio-économique majeur, la nappe alluviale de l’Allier constituant la principale ressource en eau potable pour une population d’environ 100 000 habitants. D’un point de vue hydrodynamique, l'eau souterraine circule généralement du sud au nord, avec une alimentation naturelle à partir des coteaux adjacents, dans la partie non-pompée de l'aquifère. Dans la zone de pompage, cette circulation naturelle est modifiée par le pompage qui fait pénétrer l’eau de la rivière Allier dans l’aquifère. La recharge de l’aquifère dépend alors de quatre pôles de mélange : pluie, rivière Allier, coteaux adjacents et partie sud, non-pompée, de l’aquifère. Les résultats chimiques et isotopiques obtenus permettent de cartographier la contribution de chaque pôle de mélange. [...] Ces résultats mettent en évidence la vulnérabilité de l’aquifère face aux pollutions. Les parties méridionale et orientale du site sont affectées par des arrivées d’eaux de qualité médiocre démontrant l’importance de la définition d’un périmètre de protection adaptée. Près de l’Allier, une attention particulière doit être portée non seulement aux pollutions ponctuelles qui peuvent se produire sur le cours de la rivière, mais également aux pollutions chroniques liées notamment aux rejets des stations d’épuration pourvoyeurs de polluants tels les molécules pharmaceutiques. Toutes les informations acquises devront être incluses dans les stratégies de gestion d'eau souterraine afin protéger la durabilité de cette ressource de valeur. Les résultats s’appuient sur les investigations menées sur la nappe alluviale de l’Allier, néanmoins la méthodologie utilisée et sa transposition à des systèmes analogues est l’une des perspectives majeures de cette étude<br>Hydrodynamic, hydrochemical (major ions, traces, pharmaceuticals and pesticides), and isotopic investigations (oxygen-18 and deuterium) were carried out on 19 points, including boreholes, piezometer, surface water, and springs from February 2011 to November 2012, to assess groundwater quality in the unconfined shallow alluvial aquifer of the Allier River (one of the main tributary of the Loire River). The study area, located near the city of Clermont-Ferrand (France), plays an important socio-economic role as the alluvial aquifer is the major source of drinking water for about 100 000 inhabitants. The objective of the project aims at understanding the functioning and the vulnerability of alluvial aquifers that occupy a pre-eminent position in the hydrogeologic landscape both for their economic role - production of drinking water and agricultural development - and for their ecological role. Moreover, this study also targets at determining the factors and processes controlling shallow groundwater quality and origin. The water circulates from the south, with a natural alimentation from the hills in the non-pumped part of the alluvial aquifer. In the pumping zone, this general behaviour is altered by the pumping that makes the water from the Allier River enter the system in a large proportion. Four end-members have been identified for the recharge of the alluvial groundwater: rainfall, Allier River, surrounding hills’ aquifer and the southern non-pumped part of the alluvial system. Results indicate that, despite the global Ca-HCO3 water type of the groundwater, spatial variations of physico-chemical parameters do exist in the study area. Ionic concentrations increase from the Allier River towards east due either to the increase in the residence time or a mixing with groundwater coming from the aquifer’s borders. Stable isotopes of the water molecule show the same results: boreholes close to the river bank are recharged by the Allier River (depleted values), while boreholes far from the river exhibit isotopic contents close to the values of hills’ spring or to the southern part of the alluvial aquifer, both recharged by local precipitation. One borehole (B65) does not follow this scheme of functioning and presents values attesting of a probable sealing of the Allier River banks. Based on these results, the contribution of each end-member has been calculated and the functioning of the alluvial system determined. According to this general scheme of functioning, origins of pollution (agricultural, urban) have been determined and clues to the protection of such hydrosystems defined
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Mogren, Lars. "Quercetin content in yellow onion (Allium cepa L.) : effects of cultivation methods, curing and storage /." Alnarp : Dept. of Crop Science, Swedish University of Agricultural Sciences, 2006. http://epsilon.slu.se/200696.pdf.
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MINTO, RICCARDO. "Framework for Collaborative Robotic Systems." Doctoral thesis, Università degli studi di Padova, 2022. https://hdl.handle.net/11577/3467168.
Full textAbstract:
Nell'ultimo decennio, i robot collaborativi, o più semplicemente cobot, stanno diventando sempre più comuni grazie alla loro abilità di condividere lo spazio di lavoro con l'operatore. In questo modo è possibile migliorare le prestazioni dei sistemi industriali, e in particolare quelli di assemblaggio, grazie alla possibilità di unire la flessibilità dei sistemi manuali con le prestazioni della robotica tradizionale. Per di più, è possibile automatizzare parzialmente tutti quei task che precedentemente era troppo difficile o costoso automatizzare.
Nonostante i loro vantaggi, l'utilizzo di robot collaborativi nel contesto industriale è ancora limitato a causa dei loro svantaggi. Infatti, le loro prestazioni sono limitate se confrontate con i robot tradizionali, per motivi di sicurezza, e potrebbe non essere possibile ottimizzare le loro traiettorie se si considera la necessità di evitare l'operatore. Inoltre, una cella collaborativa è solitamente separata dall'impianto principale, limitando il suo impatto nella produzione. Queste considerazioni sono complicate ulteriormente nel caso di sistemi collaborativi multi-risorsa, ovvero sistemi con un numero di risorse maggiore di 2.
Scopo di questo lavoro è risolvere questi svantaggi presentando un framework, quindi un set di algoritmi, che integrino i robot collaborativi nel contesto industriale, con maggiore attenzione ai sistemi collaborativi multi-risorsa. Questo significa non solo sviluppare un algoritmo di allocazione dei task e di comunicazione per gestire i cobot e i robot tradizionali che compongono l'impianto, ma anche sviluppare un set di algoritmi per stimare e migliorare le prestazioni di questi sistemi. Tutto ciò è ulteriormente complicato dalla necessità di considerare l'operatore umano, che richiede particolare attenzione.
Nella prima parte, questa tesi si focalizza sull'analisi delle performance di sistemi collaborativi multi-risorsa, identificando le caratteristiche di prodotto e di processo che influenzano le performance di questi sistemi e fornire un modello che permetta di valutarne la produttività dato il layout. Per integrare i diversi cobot che compongono il sistema multi-risorsa, si presenta un framework con un set di algoritmi per assegnare correttamente i task. Questo framework può essere anche utilizzato per integrare il sistema collaborativo al sistema industriale principale.
La seconda parte si focalizza sul lato umano della collaborazione uomo-robot, iniziando con la sicurezza dell'operatore presentando una strategia per evitare le collisioni. Da questa, si presenta uno studio sull'influenza dello spazio di lavoro condiviso sulle prestazioni del sistema. Infine, focalizzandosi sull'interazione fisica tra uomo e robot, si presentano due controllori adattativi basati su due metodi di apprendimento diversi. I controllori sono usati per modulare la rigidezza di un manipolatore planare usato per l'apprendimento motorio, che richiede anch'esso controllori adattativi. Infine, si presenta un confronto preliminare tra i due controllori.<br>In the last decade, collaborative robots, or simply cobots, are becoming increasingly common thanks to their ability to safely share their workspace with a human operator. This ability may improve the performance of industrial systems, with a particular focus on assembly ones, thanks to the possibility to merge the flexibility of a manual system with the performance of traditional robotics. Moreover, it is possible to partially automate tasks that were previously too difficult or too expensive to automate.
Despite their advantages, the adoption of collaborative robots is still limited in the industrial setting due to their drawbacks. Indeed, their performance are limited in comparison to traditional robots due to safety reasons, and it may not be possible to optimize their trajectory since it is necessary to avoid the operator. Moreover, a collaborative workcell is usually separated from the main industrial plant, thus limiting its effects on the production process. This is further complicated in the case of multi-resource collaborative systems, i.e., systems with a number of resources greater than 2.
The aim of this work is to solve these drawbacks by presenting a framework, thus a set of algorithms, to integrate collaborative robots in the industrial setting with a great focus on multi-resources collaborative systems. This means not only to develop a task allocation and communication algorithm to manage the cobots and industrial robots composing the plant, but also to develop a set of algorithms to estimate and improve the performance of these systems. This is further complicated by the need of considering the human operator in the loop, which requires particular attention.
In the first part, this dissertation focuses on the analysis of the performance of multi-resource collaborative systems, identifying the product and process characteristics that influence the productivity of these systems, and providing a model that allows evaluating the productivity of these systems given their layout. To integrate the different cobots composing the multi-resource system, a framework is presented, with a set of tools to correctly assign the tasks. This framework can also be adopted to integrate the collaborative system with the main industrial plant.
The second part focuses on the human side of human-robot collaboration, starting with a focus on the safety of the operator by presenting a collision avoidance strategy. From this, an analysis of the influence of the shared workspace on the system performance is presented.
Lastly, with a focus on physical human-robot interaction, two adaptive controllers based on two different learning approaches are presented. The controllers are used to modulate the impedance of a planar robot used for motor learning training, which has a similar request for adaptive controllers. Lastly, a preliminary comparison between the two controllers is presented.
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Helm, Conrad, and María Capa. "Comparative analyses of morphological characters in Sphaerodoridae and allies (Annelida) revealed by an integrative microscopical approach." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-159898.
Full textAbstract:
Sphaerodoridae is a group of benthic marine worms (Annelida) characterized by the presence of spherical tubercles covering their whole surface. They are commonly considered as belonging to Phyllodocida although sistergroup relationships are still far from being understood. Primary homology assessments of their morphological features are lacking, hindering the appraisal of evolutionary relationships between taxa. Therefore, our detailed morphological investigation focuses on different Sphaerodoridae as well as on other members of Phyllodocida using an integrative approach combining scanning electron microscopy (SEM) as well as immunohistochemistry with standard neuronal (anti-5-HT) and muscular (phalloidin-rhodamine) markers and subsequent CLSM analysis of whole mounts and sections. Furthermore, we provide histological (HES) and light microscopical data to shed light on the structures and hypothetical function of sphaerodorid key morphological features. We provide fundamental details into the sphaerodorid morphology supporting a Phyllodocida ancestry of these enigmatic worms. However, the muscular arrangement and the presence of an axial muscular pharynx is similar to conditions observed in other members of the Errantia too. Furthermore, nervous system and muscle staining as well as SEM and histological observations of different types of tubercles indicate a homology of the so called microtubercles, present in the long-bodied sphaerodorids, to the dorsal cirri of other Errantia. The macrotubercles seem to represent a sphaerodorid autapomorphy based on our investigations. Therefore, our results allow comparisons concerning morphological patterns between Sphaerodoridae and other Phyllodocida and constitute a starting point for further comparative investigations to reveal the evolution of the remarkable Sphaerodoridae.
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Rexling, Stefan. "Framgång genom modern luftmaktsteori?" Thesis, Försvarshögskolan, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:fhs:diva-5958.
Full textAbstract:
Under efterkrigstiden har ett antal operationer med luftmakt genomförts. Dessa krig har haft olika förlopp där vissa operationer har nått relativt enkla framgångar medan andra haft större svårigheter att effektivt uppnå framgång, trots överlägsna resurser. Genom en fallstudie av två moderna luftoperationer, operation Desert Storm i Irak år 1991 och operation Allied Force i Kosovo år 1999, undersöks tre luftmaktsteoretiska variablers betydelse för dessa operationers väg till framgång. Variablerna som undersöks är hämtade ur den moderna luftmaktsteori som John Warden har bidragit till att bilda och vars syfte är att bidra till att förklara hur strategisk förlamning av motståndaren uppkommer. Resultatet av undersökningen visar att systemperspektiv sannolikt bidrar till luftoperativ framgång, däremot kan inte parallell attack visas ha betydelse för att uppnå framgång. Den tredje undersökta variabeln, luftoperativ kontroll, befinns vara betydelsefull som en förutsättning för de övriga två variablernas funktion.
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Wendel-Persson, Fredrik, and Anna Ronnhed. "IT-säkerhet och människan : De har världens starkaste mur men porten står alltid på glänt." Thesis, Umeå universitet, Institutionen för informatik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-135485.
Full textAbstract:
In the ever-changing environment of the digital world one thing remains the same, the humans sitting in front of the screen. Today protecting company secrets and information is becoming more and more vital and companies invest massive amounts of money on technological defenses such as firewalls and antivirus programs, but the threats that the user and employees pose for companies go unnoticed by many. However, there are people that notice this weakness in companies’ security and try to take advantage of it for their own gain. By manipulating the human instead of the technology can a con-artist bypass companies’ security by means called social engineering. The threat that social engineering pose is no news to many within the field of information security but it’s still happening. The focus of this study is to examine why this is still an issue for a lot of companies and why it's so hard to counter social engineering. By going over previous research we identified that security culture in a company and the awareness of its employees influence the attitudes which a person needs to have to be able to fend of social engineering attacks. This study argues that attitudes determine if a person processes an incoming message through a central or peripheral route. Since a company’s security culture seemed to influence how people could counter social engineering we went to a manufacturing company and examined the security culture to try and get a better understanding on the complexity of the problem. The study concludes that being completely resilient to social engineering attacks is practically impossible. If a user will have access to a certain information, a skilled con-artist will have a chance to get their hands on that information through the user. However, the study emphasize that a company can work with improving resistance towards incoming social engineering attacks by focusing on their security culture and their employees’ attitudes and awareness concerning the problem.
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Beyvers, Stephanie. "Selective excitation of adsorbate vibrations on dissipative surfaces." Phd thesis, Universität Potsdam, 2008. http://opus.kobv.de/ubp/volltexte/2008/2551/.
Full textAbstract:
The selective infrared (IR) excitation of molecular vibrations is a powerful tool to control the photoreactivity prior to electronic excitation in the ultraviolet / visible (UV/Vis) light regime ("vibrationally mediated chemistry").
For adsorbates on surfaces it has been theoretically predicted that IR preexcitation will lead to higher UV/Vis photodesorption yields
and larger cross sections for other photoreactions.
In a recent experiment, IR-mediated desorption of molecular hydrogen from a Si(111) surface on which atomic hydrogen and deuterium were co-adsorbed was achieved, following a vibrational mechanism as indicated by the isotope-selectivity.
In the present work, selective vibrational IR excitation of adsorbate molecules, treated as multi-dimensional oscillators on dissipative surfaces,
has been simulated within the framework of open-system density matrix theory.
Not only potential-mediated, inter-mode coupling poses an obstacle to selective excitation but also the coupling of the adsorbate ("system") modes
to the electronic and phononic degrees of freedom of the surface ("bath") does.
Vibrational relaxation thereby takes place, depending on the availabilty of energetically fitting electron-hole (e/h) pairs and/or phonons (lattice vibrations) in the surface, on time-scales ranging from milliseconds to several hundreds of femtoseconds. On metal surfaces, where the relaxation process of the adsorbate via the e/h pair mechanism dominates, vibrational lifetimes are usually shorter than on insulator or semiconductor surfaces, in the range of picoseconds, being also the timescale of the IR pulses used here.
Further inhibiting factors for selectivity can be the harmonicity of a mode and weak dipole activities ("dark modes") rendering vibrational excitation with moderate field intensities difficult.
In addition to simple analytical pulses, optimal control theory (OCT) has been employed here to generate a suitable electric field to populate the target state/mode maximally.
The complex OCT fields were analyzed by Husimi transformation, resolving the control field in time and energy.
The adsorbate/surface systems investigated were CO/Cu(100), H/Si(100) and 2H/Ru(0001). These systems proved to be suitable models to study the above mentioned effects.
Further, effects of temperature, pure dephasing (elastic scattering processes), pulse duration and dimensionality (up to four degrees of freedom)
were studied. It was possible to selectively excite single vibrational modes, often even state-selective.
Special processes like hot-band excitation, vibrationally mediated desorption and the excitation of "dark modes" were simulated.
Finally, a novel OCT algorithm in density matrix representation has been developed which allows for time-dependent target operators
and thus enables to control the excitation mechanism instead of only the final state.
The algorithm is based on a combination of global (iterative) and local (non-iterative) OCT schemes, such that short, globally controlled time-intervals are coupled locally in time.
Its numerical performance and accuracy were tested and verified and it was successfully applied to stabilize a two-state linear-combination and to enforce a successive "ladder climbing" in a rather harmonic system, where monochromatic, analytical pulses simultaneously excited several states, leading to a population loss in the target state.<br>Die selektive Anregung von Molekülschwingungen mittels Infrarotlicht (IR) ist vorteilhaft, um die Wirkungsquerschnitte nachfolgender photochemischer oder photophysikalischer Prozesse zu steigern, welche durch Elektronenanregung mittels ultraviolettem (UV) bzw. sichtbarem (Vis) Licht ausgelöst werden.
Für Adsorbatmoleküle auf Oberflächen wurden theoretische Vorhersagen getroffen,
dass eine kombinierte (IR plus UV)-Strategie ("schwingungsvermittelte Chemie")
die Ausbeute bei Photodesorption und anderen Photoreaktionen deutlich zu erhöhen vermag.
Kürzlich wurde im Experiment gezeigt, dass eine rein IR-vermittelte Desorption möglich ist, welche über einen schwingungsangeregten Mechanismus erfolgt.
Hierbei wurde molekularer Wasserstoff von einer Si(111)-Oberfläche desorbiert, an der atomarer Wasserstoff und atomares Deuterium gebunden waren. Eine thermische Anregung, die zum Bindungsbruch führt, konnte hierbei wegen der Isotopenselektivität ausgeschlossen werden.
In der vorliegenden Arbeit wurde die selektive IR-Schwingungsanregung von Adsorbaten, die als multidimensionale Oszillatoren auf dissipativen Oberflächen behandelt wurden, mit Hilfe der Dichtematrixtheorie für offene Systeme simuliert.
Nicht nur die potentialvermittelte Kopplung zwischen den einzelnen Moden ist ein Hindernis für selektive Anregung, sondern auch die Kopplung der Moden des Adsorbats ("Systems") an elektronische und phononische Freiheitsgrade des Substrats ("Bades").
Die Schwingungsrelaxation verläuft hierbei auf Zeitskalen, die von Millisekunden bis hin zu wenigen hundert Femtosekunden reichen, je nach Verfügbarkeit energetisch geeigneter Elektron-Loch-Paar-Anregungen bzw. Phononen (Gitterschwingungen) in der Oberfläche.
Auf Metalloberflächen, bei denen die Schwingungrelaxation des Adsorbats zumeist von einem Elektronen-Loch-Paar-Mechanismus dominiert wird,
sind die Schwingungslebensdauern normalerweise kürzer als auf Isolator- oder Halbleiteroberflächen und betragen einige Picosekunden,
ebenso wie die Zeitskala der hier gewählten IR-Pulse.
Weitere Faktoren, die die selektive Anregung behindern können sind die Harmonizität einer Mode und die geringe Dipolaktivität sogenannter "dunkler Moden", die eine Anregung mit moderat intensiven Feldern erschweren.
Zusätzlich zu einfachen analytischen Pulsen wurden Felder mittels Optimaler Kontrolltheorie (OCT) erzeugt, um eine(n) Zielzustand/-mode maximal zu populieren.
Komplexe OCT Pulse wurden mit Hilfe der Husimi-Transformation analysiert, welche das Kontrollfeld im Zeit- und Energieraum aufzulösen vermag.
Die in dieser Arbeit untersuchten Adsorbat/Oberflächen-Systeme waren CO/Cu(100), H/Si(100) und 2H/Ru(0001), die sich als passende Modelle erwiesen, um oben genannte Faktoren zu untersuchen.
Desweiteren wurden die Auswirkungen von Temperatur, reiner Dephasierung (elastische Streuprozesse), Dauer des IR-Pulses und Systemdimensionalit"at
(Behandlung von bis zu vier Freiheitsgraden) studiert.
Einzelne Schwingungsmoden konnten angeregt werden, in vielen Fällen sogar zustandsselektiv.
Spezielle Prozesse wie die Anregung "heißer Banden", Desorption via alleiniger
Schwingungsanregung und die Anregung "dunkler Moden" wurden simuliert.
Schließlich wurde ein neuer OCT-Algorithmus in Dichtematrixdarstellung entwickelt, der es erlaubt, zeitabhängige Zieloperatoren einzuführen,
um nicht nur Kontrolle über den Endzustand einer Anregung, sondern auch über den Anregungsmechanismus zu erlangen.
Der Algorithmus basiert auf einer Kombination von globaler (iterativer) und lokaler (nicht-iterativer) optimaler Kontrollschemata in der Art,
dass kurze, global kontrollierte Intervalle zeitlich lokal miteinander gekoppelt werden.
Nach numerischen Tests wurde der Algorithmus erfolgreich angewandt, um eine Linearkombination aus zwei Zuständen zu stabilisieren, sowie um eine schrittweise "Leiteranregung" in einem harmonischen System zu forcieren, bei dem monochromatische, analytische Pulse mehrere Zustände zugleich anregen und somit einen Populationsverlust im angestrebten Zielzustand zur Folge haben.