The aim of this work is to better understand the factors and mechanisms leading to the supramolecular organization of collagen layers adsorbed on polymers. Native collagen adsorption on polystyrene (PS) and plasma-oxidized polystyrene (PSox) substrates revealed that the adsorbed layer consists in two parts: a dense and thin sheet (~ 10 nm) in which fibrils are formed, as revealed by atomic force microscopy, and an overlying thick layer (~ 200 nm) which contains protruding molecules, as revealed by quartz crystal microbalance with dissipation monitoring. The protruding molecules are in low density but modify noticeably the local viscosity. Faster and enhanced fibril formation takes place on hydrophobic compared to hydrophilic substrate. As a result of drastic thermal denaturation, the ability of collagen to assemble into fibrils is lost and the number of protruding molecules responsible for higher viscosity is reduced. Radiochemical measurements showed that collagen molecules are more easily displaced when adsorbed on a hydrophobic substrate compared to a hydrophilic substrate. This may explain why fibril formation occurs more readily on the more hydrophobic substrate, but is in contrast with higher surface affinity. The possible explanation of this paradox by the quick formation of a dense layer of collagen molecules having a smaller number of contact points with a very hydrophobic surface could not be demonstrated by a comparison of adsorption procedures. Comparing different collagen sources revealed various modes of aggregation with different characteristics regarding size and order (large fibers in solution, smaller fibrils to featureless underneath layer in the adsorbed phase). Moreover, collagen aggregation in the solution is a process competing with adsorption: more aggregated solutions behave like less concentrated solutions regarding the adsorbed amount and fibril formation in the adsorbed phase. It must be emphasized that interpretation of the QCM-D data, which is based on fitting physical quantities according to a model, has to be performed very carefully, and requires the examination of the sensitivity of the fitted data to the fitting parameters.

A frustrating aspect of the frequent changes to large VLSI CAD systems is that so little of the old available programs can be reused. It takes too much time and effort to find the reusable pieces and recast them for the new use. Our thesis is that such systems can be designed for reusability by designing the software as layers of problem oriented languages, which are implemented by suitably extending a "base" language. We illustrate this methodology with respect to VLSI CAD programs and a particular language layer: a language for handling networks. We present two different implementations. The first uses UNIX and Enhanced C. The second approach uses Common Lisp on a Lisp machine.

This thesis deals with receptivity mechanisms of three-dimensional, crossflow-dominated boundary layers. The receptivity of two model problems, a swept-flat-plate and a swept-wing boundary layer, is investigated by solving the parabolised stability equations (PSE) as well as by performing direct numerical simulations (DNS).Both flow cases are known to exhibit strong inflectional instabilities, the crossflow disturbances, whose excitation by external disturbances such as surface roughness or free-stream vorticity is studied. One focus is on worst-case scenarios. This involves the determination of optimal conditions, i.e. those disturbance environments yielding the largest possible response inside the boundary layer. A new method on the basis of the PSE is presented which allows to study optimal disturbances of swept-flat-plate boundary layers. These take the form of tilted streamwise vortices. While convected downstream they develop into streamwise streaks experiencing strong non-modal growth. Eventually, they turn into crossflow disturbances and undergo exponential growth. Non-modal growth is thus found to optimally excite crossflow disturbances and can be related to a receptivity mechanism of three-dimensional boundary layers. Evaluating effects of compressibility reveals that the potential for both non-modal and modal growth increases for higher Mach numbers. It is shown that wall cooling has diverse effects on disturbances of non-modal and modal nature. While destabilising the former it attenuates the growth of modal disturbances. Concave curvature on the other hand is found to be equally destabilising for both types of disturbances. The adjoint of the linearised Navier-Stokes equations is solved for a swept-wing boundary layer by means of DNS. The adjoint solution of a steady crossflow disturbance is computed in the boundary layer as well as in the free-stream upstream of the leading edge. This allows to determine receptivity to incoming free-stream disturbances and surface roughness as well as the corresponding worst-case scenarios. Upstream of a swept wing the optimal initial free-stream disturbance is found to be of streak-type which convects downstream towards the leading edge. It entrains the boundary layer a short distance downstream of the stagnation line. While minor streamwise vorticity is present the streak component is dominant all the way into the boundary layer where the optimal disturbance turns into a crossflow mode. Futher, the worst-case surface roughness is determined. It takes a wavy shape and is distributed in the chordwise direction. It is shown that, under such optimal conditions, the swept-wing boundary layer is more receptive to surface roughness than to free-stream disturbances. Another focus of this work has been the development and evaluation of tools for receptivity prediction. Both DNS and direct and adjoint solutions of the PSE are used to predict the receptivity of a swept-wing boundary layer to localised surface roughness. The configuration conforms to wind tunnel experiments performed by Saric and coworkers at the Arizona State University. Both the DNS and the PSE are found to predict receptivity amplitudes which are in excellent agreement with each other. Though the predicted disturbance amplitudes are slightly lower than experimental measurements the overall agreement with experimental results is very satisfactory. Finally, a DNS of the stabilisation of a transitional swept-wing boundary layer by means of discrete roughness elements is presented. This control approach is found to completely suppress transition to turbulence within the domain studied and confirms experimental results by Saric & coworkers. / QC 20111124

The correct tribological design will have a considerable effect on a gear’s service life and efficiency. The purpose of this thesis is to clarify the impact of variation in the gear tooth flank tribological system on the gear contact load capacity – to increase the understanding of how surface topography and lubricant interact. In this thesis the variation in surface topography inherent in the manufacturing method has been shown, by experimental work and computer simulations, to be an important factor for the contact condition in the early life of gears. Surface analysis revealed that the formation and composition of surface boundary layers depends strongly on the chemical composition of the lubricant, but also on pre-existing surface boundary layers. Additionally, surface boundary layers play a major role in frictional behaviour, wear and in allowing the lubricant to react properly with the surfaces. Paper A presents the current ISO 6336 calculation of surface durability. A robust design approach was used to investigate the extent to which the current standard for calculation of surface durability allows for manufacturing variations and the choice of lubricant. Paper B investigates the extent to which a logarithmical profile modification can increase gear contact pressure robustness compared to traditional lead profiles for gears. Paper C compares different gear manufacturing methods and their as-manufactured (fresh unworn) surface topographies, using measured surface topographies as input to a contact simulation program. Paper D examines surface boundary layer formation and the corresponding wear in relation to different anti-wear additives in an environmentally adapted base oil. Papers E and F make use of specimens with surface topographies imitating two gear manufacturing methods (grinding and superfinishing) to be used in a twin-disc and barrel-on-disc machine respectively. The contacts are analysed by friction measurements and simulations combined with methods for surface analysis. / <p>QC 20120925</p>

A new large eddy simulation (LES) code is developed and used to investigate non-local features of turbulent planetary boundary layers (PBLs). The LES code is based on filtered Navier-Stokes equations, which describe motions of incompressible, Boussinesq fluid at high Reynolds numbers. The code computes directly large-scale, non-universal turbulence in the PBL whereas small-scale, universal turbulence is parameterized by a dynamic mixed subgrid closure. The LES code is thoroughly tested against high quality laboratory and field data. This study addresses non-local properties of turbulence which emphasis on the stable stratification. Its basic results are as follows. The flow stability in PBLs is generally caused by two mechanisms: the negative buoyancy force (in the stable density stratification) and the Coriolis force (in the rotating system). The latter stabilizes the flow if the earth’s vorticity and the turbulent vorticity are anti-parallel. The Coriolis force stability suppresses large-scale turbulence and makes large eddies asymmetric. The density stratification suppresses vertical scales of turbulence. Joint actions of the Coriolis and the buoyancy forces result in a more complex behavior of turbulence. Particularly, the layers of vigorous turbulence may appear in the course of development of low-level jets in baroclinic atmosphere. Non-local effects determine integral measures of PBLs, first of all the PBL depth. This study clearly demonstrates its pronounced dependences on the Coriolis parameter, the Kazanski-Monin internal stability parameter, and newly introduced imposed-stability and baroclinicity parameters. An LES database is created and used to validate an advanced PBL-depth formulation. LES support the idea that PBLs interact with the stably stratified free flow through the radiation of gravity waves, excited by large turbulent eddies at the interface.

The boundary layer is the part of the atmosphere that is in direct contact with the ground via turbulent motion. At mid-latitudes the boundary layer is usually one or a few kilometers deep, while in the Arctic it is much more shallow, typically a few hundred meters or less. The reason is that here the absolute temperature increases in the lowest kilometer, making the boundary layer semi-permanently stably stratified. The exchange of heat, momentum and tracers between the atmosphere, ocean and ground under stable stratification is discussed from an observational, modeling and climate-change point of view. A compilation of six observational datasets, ordered by the Richardson number (rather than the widely used Monin-Obukhov length) reveals new information about turbulence in the very stably stratified regime. An essentially new turbulence closure model, based on the total turbulent energy concept and these observational datasets, is developed and tested against large-eddy simulations with promising results. The role of mesoscale motion in the exchange between the atmosphere and surface is investigated both for observations and in idealized model simulations. Finally, it is found that the stably stratified boundary layer is more sensitive to external surface forcing than its neutral and convective counterparts. It is speculated that this could be part of the explanation for the observed Arctic amplification of climate change.

The aim of this thesis was to study chickens of an F7 intercross between red junglefowl and White Leghorn layers in five behavioural tests to see if there were any correlations between traits in the intercross. 80 animals were used (40 males, 40 females); they were tested in a tonic immobility test, an open field, a fear of human test, an aggression test and lastly a sociality test. The results indicate a pair of correlations between the different variables; chickens with long tonic immobility duration were less aggressive, and chickens with a high fear of humans were more social towards other chickens, which could suggest a correlation between fear and social behaviour/aggression. The results from this study also support previous studies showing that one QTL controls chickens’ behaviour in the tonic immobility test based on the correlations found between the variables in the tonic immobility test. Differences between the genders were found in variables that correlated with each other; this could lead to a speculative suggestion that those behaviours are affected by genes on the X-chromosome. There was also a significant relationship between the weight of the male chickens and their behaviour in the open field test and in the fear of human test, in which the heavier males were less fearful than the lighter ones.

The poetry of Dahlia Ravikovitch presents as self-writing nestled in the wide embrace of non-linear écriture féminine. Each poem offers a glimpse of the persona: body and soul, the music of her voice and the perspective of her spirit. Together the poems comprise verbal self-portraits of a lovelorn soul, torn between impulses to fully remember and deliberately forget. Through years of love, life, disappointment, bouts of depression and renewed promise, Dahlia Ravikovitch continued to compose. Through the crystals of poetry the speaker examines, from varying angles and in multiple refractions of light, those figures of alterity who are her self. For Ravikovitch poetry was the only neutral space in which her self could comfortably exist and, even so, not always. The poet-persona experiences love in unsuitable proportions. She receives too little; she goes ‘overboard’ and ‘out of bounds’ in giving too much. She experiences love, even when accessible, as an affliction. She suffers love. She laments love. The persona performs her malaise through contrasting physical sensations, idiosyncrasies and profound cravings. Her personal thermostat is erratic. She exhibits pronounced wardrobe-predilections. Her throat reacts to a flow of eros and creative vitality or lack thereof. She yearns for pure memory and thirsts for pure essence. The speaker’s gallery displays an elaborate montage of a golden apple endowed with gifts of wisdom, eros, poetry and passion, alongside portraits of a royal chanteuse and a skilled scribe. Crucial brushstrokes illuminate lovers and sinners, souls in flames, shipwrecks, lyric-expressive throats in various states of constriction and release, as well as voices of collective responsibility. Ravikovitch encrypts her poetry with rich resources of biblical, rabbinic, medieval and early modern Hebrew literature. She forwards the linguistic and literary resonance of these layers. She innovates upon their motifs through feats in the dimensions of feminine writing, intertextual engagements and postmodern poetics.

Physical experiments are used to investigate the influence of the Coriolis forces on flow structures in channelized turbidity currents, and their implication for the evolution of straight and sinuous submarine channels. Initial tests were used to determine whether or not saline density currents are a good surrogate for particle-laden currents. Results imply that this assumption is valid when turbidity currents are weakly-depositional and have similar velocity and turbulence structures to saline density currents. Second, the controls of Coriolis forces on flow structures in straight channel sections are compared with two mathematical models: Ekman boundary layer dynamics and the theory of Komar [1969]. Ekman boundary layer dynamics prove to be a more suitable description of flow structures in rotating turbidity currents and should be used to derive flow parameters from submarine channels systems that are subjected to Coriolis forces. The significance of Coriolis forces for submarine channel systems were determined by evaluating the dimensionless Rossby number RoW. The Rossby number is defined as the ratio of the flow velocity, U, of a turbidity current to the channel width, W, and the rotation rate of the Earth represented by the Coriolis parameter, f. Coriolis forces are very significant for channel systems with RoW ≤ O(1). Third, the effect of Coriolis forces on the internal flow structure in sinuous submarine channels is considered. Since previous studies have only considered pressure gradient and centrifugal forces, the Coriolis force provides a crucial contribution to the lateral momentum balance in channel bends. In a curved channel, both the Rossby number RoW and the ratio of the channel curvature radius R to the channel width W, determine whether Coriolis forces affect the internal flow structure. The results demonstrate that Coriolis forces can cause a significant shift of the density interface and the downstream velocity core of channelized turbidity currents. The sediment transport regime in high-latitude channel systems, which have RoW << R/W, is therefore strongly influenced by Coriolis forces. Finally, these findings are incorporated into a conceptual model describing the evolution of submarine channels at different latitudes. For instance, the Northern Hemisphere channels have a distinctly higher right levee system and migrate predominantly to the left side and generally exhibit a low sinuosity. In contrast, low latitude channel systems have RoW >> R/W so that centrifugal forces are more dominant. This results in more sinuous submarine channel systems with varying levee asymmetries in subsequent channel bends. In conclusion, Coriolis forces are negligible around the equator but should be considered in high latitude systems, particularly when RoW ~ O(1) and RoW << R/W.

The poetry of Dahlia Ravikovitch presents as self-writing nestled in the wide embrace of non-linear écriture féminine. Each poem offers a glimpse of the persona: body and soul, the music of her voice and the perspective of her spirit. Together the poems comprise verbal self-portraits of a lovelorn soul, torn between impulses to fully remember and deliberately forget. Through years of love, life, disappointment, bouts of depression and renewed promise, Dahlia Ravikovitch continued to compose. Through the crystals of poetry the speaker examines, from varying angles and in multiple refractions of light, those figures of alterity who are her self. For Ravikovitch poetry was the only neutral space in which her self could comfortably exist and, even so, not always. The poet-persona experiences love in unsuitable proportions. She receives too little; she goes ‘overboard’ and ‘out of bounds’ in giving too much. She experiences love, even when accessible, as an affliction. She suffers love. She laments love. The persona performs her malaise through contrasting physical sensations, idiosyncrasies and profound cravings. Her personal thermostat is erratic. She exhibits pronounced wardrobe-predilections. Her throat reacts to a flow of eros and creative vitality or lack thereof. She yearns for pure memory and thirsts for pure essence. The speaker’s gallery displays an elaborate montage of a golden apple endowed with gifts of wisdom, eros, poetry and passion, alongside portraits of a royal chanteuse and a skilled scribe. Crucial brushstrokes illuminate lovers and sinners, souls in flames, shipwrecks, lyric-expressive throats in various states of constriction and release, as well as voices of collective responsibility. Ravikovitch encrypts her poetry with rich resources of biblical, rabbinic, medieval and early modern Hebrew literature. She forwards the linguistic and literary resonance of these layers. She innovates upon their motifs through feats in the dimensions of feminine writing, intertextual engagements and postmodern poetics.