Structural Analysis Of Cardiovascular Tissue Using Quantitative Polarised Light Microscopy

Prior to the advent of electron microscopy, polarised light was commonly used in structural research. New microscopical and mathematical methods have made the techniques worthy of reappraisal. I used quantative polarised light microscopy to examine tissue structure at both the fibre and molecular level. Birefringent materials, those with an anisotropic molecular organisation (such as collagen, muscle and elastin), can be studied using polarised light. The optical properties of birefringent materials were used to determine fibre orientation. Two-dimensional orientation was measured on the planar rotating microscope stage and three-dimensional orientation on a Universal stage. Molecular organisation, which affects optical anisotropy, was assessed by measuring the path-difference or retardation when linearly polarised light passes through birefringent materials. Five projects, focussing on collagen and muscle in cardiovascular tissues, were undertaken to demonstrate the usefulness of polarised light microscopy in structural studies.;I measured the two-dimensional orientation of cardiac muscle fibres in hypertrophic cardiomyopathy and developed a quantitative method to complement the current qualitative method of diagnosis. I used the Universal stage to measure the orientation of collagen fibres in brain arteries and found that the fibres were predominantly circumferentially aligned at normal systolic pressures, but, at higher pressures a population of fibres had large longitudinal components of orientation. I measured the retardation in scar collagen produced following myocardial infarction and found that changes in the optical properties of collagen could be detected for at least six weeks after its production. A measured difference in retardation in tendons from floppy mitral valves, indicated that degraded collagen can also be detected using polarised light. Both fibre orientation and molecular organisation were assessed in cerebral saccular aneurysms. The aneurysm wall was layered and the collagen fibres were organised in a complex three-dimensional weave, suggesting a strong structure; however, the retardation in the aneurysm was lower than normal, indicating less molecular organisation and a possible reason why aneurysms enlarge and rupture.;The general conclusion is that quantitative polarised light mircoscopy remains an effective method in structural analysis

Nonminimal state space approach to multivariable ramp metering control of motorway bottlenecks

The paper discusses the automatic control of motorway traffic flows utilising ramp metering, i.e. traffic lights on the on-ramp entrances. A multivariable ramp metering system is developed, based on the nonminimal state space (NMSS) approach to control system design using adaptive proportional-integral-plus, linear quadratic (PIP–LQ) optimal controllers. The controller is evaluated on a nonlinear statistical traffic model (STM) simulation of the Amsterdam motorway ring road near the Coen Tunnel

Le système financier montréalais : quelques lacunes

The objective of this paper is to describe some important gaps in the Montreal financial community. These gaps are examined in turn from the points of view of the small investor and the small business.

ICT in the classroom - Gaps between policy and practice?

En el aprendizaje de las lenguas extranjeras, obligatorio para estudiantes de 8 a 14 años según el Currículo Nacional Inglés, la necesidad de integrar la tecnología en los métodos de enseñanza ha sido evidente: “las escuelas deberían utilizar una gran variedad de recursos, incluyendo TIC, para acceder a la información y comunicarse en la lengua meta” (Departamento de Educación, 2007). El estudio muestra los motivos por los cuales los profesores hacen uso de la tecnología así como su impacto en la motivación del alumno. Descubre también una clara tendencia de usar TIC para presentar el idioma en lugar de para promover un aprendizaje autónomo y personalizado. Los alumnos expresan una satisfacción subjetiva ante la tecnología utilizada en el aula de lenguas modernas así como el deseo de hacer uso de dicha tecnología de una forma más independiente. La tecnología gira, según este estudio a pequeña escala, alrededor de la figura del profesor, quien se encarga de su uso, y son escasos los ejemplos de las posibilidades comunicativas de naturaleza autónoma descritas previamente. Las conclusiones derivan de los cuestionarios realizados por 60 estudiantes y (sus) 2 profesores, así como de las conversaciones con los profesores de dos escuelas públicas inglesasIn foreign language learning, required by the government's National Curriculum for children in England aged 8 to 14, the integration of technology into teaching methodologies has been explicit: "schools should use a range of resources, including ICT, (Information and Communication Technology) for accessing and communicating information in the target language" (Deparment for Education, 2007). This reseach investigates the role of ICT in language learning inside two English classrooms -a primary and a secondary - in order to explore the nature of motivation in educational technology from both the student and teacher perspective. The study elicits teachers' reasons for deploying the technology along with their emphases on the motivational advantages of ITC. It finds a marked tendency to use ICT for presentational, rather than autonomous or personalised learning. Children express subjective satisfaction with tecnology deployed in language learning and a desire to operate the technology more independently. Teh techonology is, from this small scale study, tecaher-led and teacher-driven, with few instances of the more autonomous communication possibilities outlined above (Department form Education, 2007). Field research findings derive from questionnaires of 60 pupils and (their) 2 teachers, as well as semi-structured interviews with teachers in two mainstream English school setting

Modelling the hydrodynamic drag force of flexible riparian woodland

In this thesis, two practical models for predicting the drag force exerted on flexible riparian vegetation under hydrodynamic loading have been developed. The models were formulated based on the results of a unique experimental data set that consisted of high resolution force-velocity and physical property measurements for twenty-one full-scale riparian trees, in both foliated and defoliated conditions. One of the models has then been used to numerically simulate the impact of riparian woodland on the flooding characteristics of a mid-catchment river site. Analysis of photographs and video footage of the trees from the experimental study during drag force testing allowed the frontal projected area to be determined, both in still air and as a function of flow velocity. The observed reductions in projected area and drag coeffcient with velocity were normalized using the projected area in still air to provide an empirical relationship between the ‘rigid’ drag coeffcient and area Reynolds number. The resulting drag force predictions were found to be accurate when properly calibrated against the vegetation under consideration. A second, more physically based model to predict the reconfiguration of flexible vegetation has been developed based on dimensional analysis of the relevant parameters, including flexural rigidity. The model utilizes a novel vegetative Cauchy number to determine the extent of the reconfiguration and has been shown to be more accurate than two existing drag force models. The model has also been validated against independent drag force data, demonstrating that it is applicable to vegetation of differing scale, morphology and flexibility. Serial and parallel optimizations of an existing two-dimensional hydrodynamic modelling code have enabled detailed numerical simulations of extreme flood events to be undertaken for a mid-catchment river site in Somerset, UK. The results indicated that riparian vegetation has a minimal impact on the downstream flooding characteristics, at least for the small site investigated herein. Significant reductions in key flow properties, namely velocity and bed shear stress, were however observed within the vegetated areas