Les résultats de cette recherche concernent trois volets :<br />Le volet théorique (partie I) présente une modélisation générale du comportement thermo-hydro-mécanique de sols non saturés. Le modèle prend en compte la déformation du squelette, la filtration des phases liquide et gazeuse, la diffusion de vapeur, la conduction de chaleur et le changement de phase liquide-vapeur. Cette modélisation est utilisée pour décrire le transport d'eau dans un sol non saturé en favorisant les phénomènes de filtration de liquide, de diffusion de vapeur d'eau et de changement de phase d'eau liquide-vapeur. <br />Le volet instrumental (partie II) porte sur la réalisation d'un banc de sorption et d'un dispositif de type plaque de pression en température. Ces matériels permettent de réaliser des essais de désaturation et de déterminer la courbe caractéristique sol-eau. Un autre aspect concerne la rénovation d'un appareil triaxial thermique en le dotant d'une instrumentation plus adaptée à l'étude du comportement thermo-hydro-mécanique de sols non saturés.<br />Le volet expérimental est double. Le premier aspect (partie III), relatif à l'étude de la désaturation et à la détermination de la courbe caractéristique d'une argile plastique et d'un sable limoneux argileux à 20°C et 60°C, porte sur la détermination d'un coefficient de transport en phase liquide. Le second aspect (partie IV) s'intéresse à la représentation de surfaces de charge dans le cas du sable limoneux argileux non saturé à différentes températures. Cette surface de charge présente un caractère thermo-extensif dont on propose une modélisation et une interprétation physique.

This paper analyzes the effect of political and economic factors on the risk of regime change in countries between 1975 and 2010, using survival analysis with time-dependent covariates. The findings show that negative economic growth increases the risk of regime change in the following year, and that a higher level of GDP per Capita, as well as international trade, has an inhibiting effect on the risk of regime change in democracies. The results also show that countries with young regimes are more likely to experience a regime change, and that countries with a long tradition of democratic governance suffer virtually no risk of experiencing a regime failure. These findings lend heavy support to the democratic consolidation theory, while giving mixed support to other theories of economic and political causes of regime change. The more generalized approach to regime change used in this paper provides a stepping stone for opening up a greater understanding of the mechanisms which cause regime change in all types of governments, and regardless of the direction of the change in relation to democracy.

Consolidation of Acute Care Surgical Services (ACSS) as a response to multiple challenges in providing timely and high-quality emergency services is a growing interest among healthcare policymakers. However, very little is known about patient experiences within this system. This study explores patient perceptions of their acute care surgical experiences within a consolidated ACSS program. A qualitative study guided by the tenets of Appreciative Inquiry was conducted. Data were collected by means of semi-structured interviews and personal stories. Thirteen participants were involved, seven females and six males of varying ages; all underwent emergency surgeries including appendectomy, cholecystectomy, and small bowel obstruction surgery. Findings suggest that clear and effective communication, excellent nursing care, timely access to surgical services, continuity of care, patient safety, transfer to an Acute Care Surgical (ACS) site, communication regarding transportation, and process of admission to an ACS site play important roles in patient experiences within a consolidated ACSS.

This research is a theoretical, experimental and numerical study of the one-dimensional deformation of suspensions. The study is focussed on the transition between sedimentation and consolidation, and creep during soil consolidation. In the literature, sedimentation, traditional large strain consolidation and creep are explored independently. The theory of sedimentation has been derived in parallel with the mathematical description of shock waves. The large strain consolidation theory of Gibson et al. (1981) has been adopted, and attention is given to the material properties of compressibility and permeability. Traditionally creep has been studied on thin samples, and a review is given to identify parallels with creep behaviour of the thick samples studied here. The experimental work was carried out in the laboratory using settling column tests. During the sedimentation stage, when the soil particles are fluid supported, shock waves were monitored and tracked by means of an X-ray absorption technique to allow for the calculation of experimental flux functions. Settling column experiments on different natural soils have been performed to study the consolidation behaviour by means of the measurement of pore water pressure and X-ray density measurements. An in-depth study of the development of effective stress has been performed to quantify the creep behaviour of the soils studied in a strain rate surface. The sedimentation equation is classified as a hyperbolic partial differential equation. In this kind of equation, discontinuities can propagate, and standard solution methods, eg finite differences, fail to give adequate results. For this reason codes have been developed using the finite volume method (FVM) to solve the sedimentation equation numerically. A standard numerical code has been developed for the solution of the large strain consolidation equation, while for the unified sedimentation-consolidation model the finite volume method (FVM) has been used. The shock waves monitored in the experiments are successfully predicted by the sedimentation model using experimentally derived flux functions. This study made it possible to formulate a physically and mathematically correct definition of the transition from sedimentation to consolidation. The strengths and weaknesses of the traditional large strain consolidation model have been identified by means of an international Class A prediction seminar. A new unified sedimentation-consolidation model is proposed using a flux function, a permeability relationship and a strain rate surface as material functions. Successful predictions of experiments have been performed, showing the transition from sedimentation to consolidation and the inclusion of creep.

An understanding of the behaviour of newly deposited soil is important because of its direct applications in fields such as harbour siltation and storage of dredge slurries. In coastal regions the dominant mode for deposition of fine-grained cohesive material is through flocculation- the electrostatic aggregation of mud particles. The present study focuses on the measurement of both flocculation conditions and bed properties, towards the understanding of the influence of the former on the latter. A computerised laboratory setup, complete from sedimentation and flocculation to the long term consolidation allows each of these processes to be observed in instrumented perspex columns without the many variables present in an estuary. The bed deposition rates resemble those found in natural estuaries, and therefore this technique is a much improved method for examining natural processes than the method of slurry deposition, which is normally employed in soil mechanics. An image acquisition and analysis system has been designed specifically for this work. Image sequences are analysed in real time to give information about the dimensions and concentration of the particles, and the particle velocities. Floc sizes increase as the particle concentration increases in the column. Increasing the concentration further leads to an overall hindering of the sedimentation rate and breakup of the flocs. Images of beds formed through slow sedimentation clearly show aggregate features that are not present in slurry experiments. From low to medium sedimentation rates the bed height, normalised by the mass of sediment in the bed, increases. From medium to high rates of sedimentation, however, the normalised bed heights decrease. Overall slurry experiments have lower bed heights than slowly deposited experiments. Image analysis of the bed surface (top 0.5mm) has revealed that aggregates which are present immediately after deposition are broken down over tens of hours. The ISIS instrument has been modified to gather information about the resistance to erosion of the beds. A bed is more easily eroded after it has had a long period of consolidation. X-ray density measurements and imaging techniques are used to link the strength of the bed to biological factors. X-ray bulk density and pore pressure measurements allow calculations of void ratio, porosity, and effective stress. Bender element apparatus has been constructed to measure shear stiffness of the soil, and bed strength measurements are made using a shear vane. It is found that variations in the sedimentation conditions have significant effects on bed density and on void ratio. These effects continue to be visible in the consolidated bed, even after an order of magnitude increase in the total vertical bed stress (equivalent to the range of metres of overburden pressure). The variations in the bed structure can have profound effects on bed strength. Methods to compare floc measurements to bed measurements are complicated by the inherent variation in floc data. Possible techniques include the use of solids volume fraction, fractal dimension and intrinsic sediment properties. The usefulness of each of these is assessed. It is suggested that it is the frequency at which the bed is bombarded by flocs, and not the properties of the flocs themselves, that largely determines the bed properties.

Introduction: When fine grained natural sediments or artificially produced waste materials are transported and deposited through water, several different phases of behaviour are observed. These have been described variously as suspension, free settling, compression settling, intermediate and consolidating soil phases. Transitions between each are not always distinct in terms of material properties or behaviour and time spent in the early phases before a conventional soil state is attained can be a significant proportion of the total period of engineering interest. The eventual state attained following procession through these stages may be very different to that if the soil had been remoulded at the same final density. Standard engineering models exist which can describe soil behaviour well in separate phases under particular conditions, but these are of limited validity when extended to more general conditions and wider volumetric ranges than those for which they were formulated. The number of factors required to describe the entire range of behaviour is consequently larger than that for any one phase, and many of these factors are more familiar in fields of chemistry, geology or sedimentology than in classical soil mechanics. This thesis discusses, in engineering terms, the engineering behaviour observed in a particular soil during the general sedimentation and self weight consolidation process. In the second chapter existing knowledge about behaviour at zero or low stresses is reviewed and evaluated with respect to common assumptions made, often implicitly, in formulating predictive models. It is shown that while these models have been extensively developed to a stage where they can approximate many aspects of soil behaviour, the lack of fundamental investigations carried out in parallel with their development has often led to inadequate appreciation of the causes of discrepancies between modelled and real behaviour. This has occurred particularly where standard geotechnical testing equipment and methods devised for stiff soils have been used to obtain global average relationships between engineering parameters. Even where modified tests have been developed, instrumentation has sometimes been inadequate and measurements too infrequent, so that data available have necessarily been analysed only in terms of constitutive forms assumed already. In chapter three experimental techniques are proposed which, where possible will allow soil behaviour to be examined under the least restrictive conditions of one dimensional compression so that basic engineering concepts may be analysed. Chapter four describes the testing programme and presents direct results of experiments. Chapter five analyses compression behaviour and establishes some trends which can be observed for particular parameters and relationships, and which exist between experiments under different initial and boundary conditions. Similar analysis of strength behaviour is undertaken in chapter six, where results obtained using different testing methods are compared. In the final chapter the general relevance of these results and their implications for engineering problems are discussed. Some suggestions are made for future work. Areas of application Improved knowledge about cohesive waterborne sediments can result in considerable savings for related industries. In the United Kingdom the annual cost of maintenance dredging is £25m (I.C.E. Costal Engineering Research Panel, 1985). In East Coast ports alone reduction of the distances travelled by each dredger would lead to a saving of £270,000 per annum, per kilometre reduction. Studies at Rotterdam Europort (Kirby, Parker, van Oostrum, 1979) show that although a channel dredged recently may quickly refill with sediment to a depth which echo-sounding techniques might indicate to be unnavigable, the strength may be so low as to allow passage of vessels virtually unimpeded. A density of 1.2 Mg/m3 is now used by the Rijkswaterstaat to define the "Nautical Depth" of a channel, stated to be "a density within the suspension above whose altitude vessels can safely sail." Dredging control using information from gamma ray densimeters has enabled production increases of up to 50% to be obtained in the Europort area. In the United States $30m was spent in a 5 year period on a dredging research programme aimed at improving disposal methods (Haliburton, 1977). Considerable volumes of waste material are also produced by the mining industry. The phosphate industry in Florida produces 40 million tons by dry mass per annum at an initial 3% solids by mass which even after two years retains void ratios around 10, due to the high content of attapulgite, a clay mineral consisting of long fibrous particles with large specific surface. Disposal areas for these clays occupy over 50,000 acres and are surrounded by 300 miles of dams, posing significant environmental and safety problems (Bromwell, Oxford, 1977). Failures of underwater slopes have been well documented. In muds deposited recently in the Mississippi Delta area very low shear strengths combine with apparently high excess pore pressures and presence of gas bubbles to cause instability for slope angles less than 1°. Recent research carried out a Oxford suggests that presence of gas may cause high excess pressures to be deduced where none exist. Duncan and Buchignani (1973) analysed a slope failure in San Francisco Bay which occurred during cutting of a slope from a normally consolidated clayey silt. The importance of accurate determination of an in situ parameters for analysis was shown by the estimated saving of $200,000 through using a slope of 7:8 rather than 1:1, decreasing the supposed safety factor from 1.26 to 1.17. Analysis of error sources showed that an error of only 4% in the soil density could reduce this safety factor by 10%. Similar problems due to changes in loading or boundary conditions occur where natural changes, such as increase in water current, cause erosion of a sediment layer which might, for example, be supporting an underwater cable or pipeline. In all these areas in situ property determination in solid of low density provides major problems. Density is often the only quantity that can be measured both accurately and continuously and then only when a stable platform can be maintained. Recovery of high quality samples from these layers is virtually impossible, so that there is a strong need for correlations between density and other properties such as strength and compressibility.

Large voids created by underground mining are backfilled to provide regional ground support. This thesis examines using conventional oedometer techniques and electromagnetic (EM) techniques to characterize consolidation and binder hydration in mine backfill so that EM monitoring can be used in the field to provide real-time feedback to operators to optimize the backfilling process. New techniques are given for interpreting the full range of deformation (initial compression, primary and secondary consolidation). Deformation due to initial compression is non-trivial and may have to be accounted for in numerical back-analyses of field case studies. EM parameters are sensitive to binder content, progress of hydration and loss of water caused by consolidation and binder hydration. The integrated interpretation of consolidation and EM behaviours has significant potential impact on real-time monitoring of mine backfill operations, and recommendations are made to advance the technique for this purpose.

Large voids created by underground mining are backfilled to provide regional ground support. This thesis examines using conventional oedometer techniques and electromagnetic (EM) techniques to characterize consolidation and binder hydration in mine backfill so that EM monitoring can be used in the field to provide real-time feedback to operators to optimize the backfilling process. New techniques are given for interpreting the full range of deformation (initial compression, primary and secondary consolidation). Deformation due to initial compression is non-trivial and may have to be accounted for in numerical back-analyses of field case studies. EM parameters are sensitive to binder content, progress of hydration and loss of water caused by consolidation and binder hydration. The integrated interpretation of consolidation and EM behaviours has significant potential impact on real-time monitoring of mine backfill operations, and recommendations are made to advance the technique for this purpose.

Long-term memories turn labile with reactivation and undergo a re-stabilization process, termed reconsolidation, involving molecular changes that allow updating of an existing memory trace. Such molecular changes may involve the activation of kinases and expression of proteins related to the increase of synaptic plasticity and memory formation. A kinase reported to have a role in a variety of memory tasks is the extracellular signal-regulated kinase 1/2 (ERK1/2). The downstream activation of ERK targets other regulatory enzymes, transcription factors and cytoskeletal proteins, which allow structural changes in the neuron due to protein synthesis up-regulation. Among the proteins up-regulated by ERK activity is the activity-regulated cytoskeleton-associated protein (ARC), an immediate early gene related to synaptic plasticity. The phase-dependent roles of ERK and ARC have not been examined as part of the molecular mechanisms triggered after a learning experience. In this study I used conditioned taste aversion (CTA) as the learning paradigm and investigated the expression of pERK and ARC in brain regions critical for taste information processing such as the insular cortex and the amygdala. A differential pattern of protein expression was observed in the insular cortex (IC) two hours after taste memory acquisition: pERK activity increased in the aversively conditioned group while ARC increased in the group that received only the novel taste. The central amygdala (CeA) showed a significant increase in pERK, but not ARC activity after CTA training. Immunoblotting experiments performed after memory retrieval in the appetitive group show that pERK continues to signal aversive taste to the IC with ARC exhibiting heightened expression an hour later. An increase in ARC expression 30 minutes after reactivation of the aversive taste was seen in the basolateral amygdala and the CeA exhibited a similar increase at 60 and 90 minutes. Local infusion of ARC antisense oligonucleotides within the IC interfered with the consolidation of safe taste memories, but not with their acquisition. Trace update experiments showed that ARC influences the memory switch from aversive to safe, but not the reverse. Our results indicate that ARC plays a critical role in consolidation and updating of safe taste memories, and the ARC signaling could possibly elicit ERK activation.

The study aimed to identify mud brick and mud plaster technology of Hittites by examining some burnt mud brick walls of Shapinuwa Hittite city and to point out repair and conservation needs of those burnt mud brick structures. The walls were documented by mapping the visual decay forms. The bulk density, total porosity, water absorption by capillarity and water vapour permeability were obtained as basic physical properties. The mechanical properties were expressed by the modulus of elasticity and the uniaxial compressive strength. Compositional and mineralogical properties were determined by optical microscopy, XRD, TGA and SEM coupled with EDX, and by XRF analyses. In addition, pozzolanic activity of powdered samples was determined.. The samples studied had low bulk density, high porosity and high water vapour permeability. The Emod values and the UCS values showed that their mechanical properties were comparable with some historic mortars and bricks. The petrographic and mineralogical analyses of burnt materials indicated a mud brick composition containing fine and medium sized siliceous aggregates mainly composed of quartz. The binder was concluded to be composed of kaolinite illite and micritic calcite that indicated the use of ideal soil compositions by Hittites to make lime stabilized mud bricks, in terms of today standards. The temperature during the fire was estimated to be around 700-800 C. The high pozzolanicity of burnt mud bricks and plasters, provided an opportunity to repair the structure using pozzolanic lime mortars to produce good adhesion. The first results of consolidation treatments had shown that the physical and mechanical properties of burnt mud brick can be improved by impregnation with ethylsilicates such as Tegovakon V.