The assessment of pre-morbid levels of intellectual functioning in people with dementia

This thesis consists of three papers: a literature review, an empirical paper and a reflective paper. The literature review considers the validity of measures of premorbid intellectual functioning with people with varying levels of dementia severity. It aims to be of use to British clinicians by focussing specially on tests that were designed for use with a British English speaking population. No single measure of pre-morbid intellectual functioning is found to be valid for use with people of all levels of dementia severity. The use of multiple measures for estimating pre-morbid intellectual functioning are indicated. The empirical paper investigates the relationship between a person’s pre-morbid level of intellectual functioning and the amount of cognitive decline that they experience prior to gaining a diagnosis of dementia. It uses a retrospective correlational design to analyse data from existing memory clinic files. A significant positive Pearson’s correlation coefficient is found between pre-morbid intellectual functioning and amount of cognitive decline at the point of diagnosis, in all three of the diagnostic groups. This suggests that people with high pre-morbid functioning have to undergo greater cognitive decline before they are given a diagnosis of dementia. Changes to current clinical practice are indicated which take account of relative amounts of cognitive decline in the diagnostic process. Finally, a reflective account is presented which is based on the author’s thoughts and experiences of carrying out research in the field of dementia. This focuses on the challenges in accessing retrospective clinical data. Suggestions are made regarding future research and clinical practice

Stacking-induced fluorescence increase reveals allosteric interactions through DNA

From gene expression to nanotechnology, understanding and controlling DNA requires a detailed knowledge of its higher order structure and dynamics. Here we take advantage of the environment-sensitive photoisomerization of cyanine dyes to probe local and global changes in DNA structure. We report that a covalently attached Cy3 dye undergoes strong enhancement of fluorescence intensity and lifetime when stacked in a nick, gap or overhang region in duplex DNA. This is used to probe hybridization dynamics of a DNA hairpin down to the single-molecule level. We also show that varying the position of a single abasic site up to 20 base pairs away modulates the dye–DNA interaction, indicative of through-backbone allosteric interactions. The phenomenon of stacking-induced fluorescence increase (SIFI) should find widespread use in the study of the structure, dynamics and reactivity of nucleic acids

Experimental and numerical study of the hydrodynamics of an isolated bubble in non-Newtonian liquid phase in a thin gap bubble column

International audienceDevelopment of photobioreactors (PBR) for microalgae cultivation is a primary concern, keeping in mind the applicative potential of these photosynthetic microorganisms. For this purpose, optimization of culture parameters and PBRs design are the two possible solutions in order to obtain high volumetric productivities. The thin-gap intensified PBR allows to obtain these performances via an increase of culture concentration for a given illuminated surface. When compared with usual PBRs, the confinement results in a high change of the hydrodynamics and mass transfer[1]. To optimize these production systems, our study focuses on the characterization of local hydrodynamics in a 2D bubble column of 4 mm thickness (FIG. 1). Furthermore, it has been shown that the increase in cell concentration is accompanied by rheological properties modifications of the microalgae suspension. To mimic such high concentration of Chlorella vulgaris cultures which have non-Newtonian shear thinning behaviour at concentrations ranging from 30-40 g/L[2], solutions of Xanthan Gum (XG) and Carboxymethyl cellulose (CMC) are used respectively at the concentrations of 1 g/L and 2 g/L. In order to put forward the effect of the rheological behaviour, demineralized water is also used as a Newtonian fluid. In this preliminary work, the main purpose is to estimate the terminal velocity (V t) of an isolated bubble in this confined column. In fact, if the terminal velocity for an isolated bubble is modified due to wall effects, there will have consequences for hydrodynamics and mass transfer of the whole bubble column: for instance, bubble residence time or gas hold up will be modified[1]. B.Figueroa Espinoza et al. [3] reported the confinement effect for a single clean bubble, pointing out that the drag coefficient widely increases for oscillating bubbles rising in a Hele-shaw cell. The experimental part consists in studying the local hydrodynamics behaviour of isolated bubbles of different diameters for three liquid media: water, CMC and XG solutions. Capillaries tubes, having diameters (d c) of 0.127, 0.264, 0.508, 0.762 or 1.016 mm are used to generate isolated bubbles at different diameter sizes with the help of a low-pressure syringe pump (NEMESYS, GERMANY). Bubble injection is performed 7 cm away from the lateral wall which can be considered sufficient to avoid wall influence on the hydrodynamics of isolated bubble. Bubble size and instantaneous bubble velocity are estimated by a shadowgraphy method using the DANTEC DYNAMICS Shadow Strobe. These measurements are performed at mid height of the column, where bubble terminal velocities have been reached. The experimental terminal velocities for different bubble diameters (d b) in water, CMC and XG liquid media are reported in Table 1 and plotted in FIG. 2(a). Water measurements are also compared to the correlation established by M.Jamialahmadi et al.[4] and the data of R.Clift et al. [5] which concern isolated bubble in pure water in infinite liquid medium (FIG. 2(b)). It is found that for an isolated bubble rising in quiescent liquid, with a diameter lower than 4 mm, the terminal velocity is divided by V t ratio between 1.2 and 1.6 for water. Besides this in non-Newtonian solutions, for lower bubble diameters the terminal velocity is less than water medium and as the bubble diameter increases it becomes constant this phenomena was also experienced by Shahram Amirnia et al.[6]. In parallel to experiments, a numerical study is performed to characterize the behaviour of one single bubble in the confined space between two walls in Newtonian and Non-Newtonian media. Simulations are performed with academic Ansys Fluent 17.2 solver using volume of fluid (VOF) method for interface tracking along with continuum surface Force (CSF) model to treat surface tension. Firstly, mesh independency verification has been performed by 2D and 3D simulations of a 3 mm diameter bubble in infinite medium. These results have been validated with the results of F.Bertola et al.[7](FIG.2(b)). Thereafter the same confined geometry as experimental setup has been adopted to simulate the bubble diameters determined experimentally. Numerical results are reported in FIG. 2(b) and seem to be in good agreement with the experiments results (FIG 2(b))

A Course or a Pathway? Addressing French as a Second Language Teacher Recruitment and Retention in Canadian BEd Programs

Institutions strive to offer programs that address both the needs of the educational system and incorporate current pedagogical research. Creating a program that is relevant, inspiring, and accessible to aspiring French as a Second Language (FSL) teachers, while also equipping them with the skills and knowledge deemed necessary by the education system, is a delicate balancing act. This study reviewed 44 FSL teacher education programs that lead to professional certification across Canada. Environmental scans drew information from the program websites related to admission requirements, program structure and content, practicum, and graduation criteria. Follow-up interviews with program stakeholders were conducted to verify or clarify the data. The results highlight the inconsistencies that exist among programs for developing FSL educators. We position the ways in which Canadian faculties of education might provide a more holistic “pathway” approach to recruiting, preparing, and retaining emerging FSL teachers.Les établissements qui préparent les futurs enseignants de français langue seconde (FLS) s’efforcent d’offrir des programmes qui répondent à la fois aux besoins du système éducatif et qui intègrent les recherches pédagogiques actuelles. Créer un programme à la fois pertinent, inspirant et accessible aux futurs enseignants de FLS, tout en les dotant des compétences et des connaissances jugées nécessaires par le système scolaire, est un exercice d’équilibre délicat. Cette étude a examiné 44 programmes de formation des enseignants de FLS qui mènent à la certification professionnelle au Canada. Des analyses de l’environnement ont permis de tirer des informations des sites Web des programmes concernant les conditions d’admission, la structure et le contenu du programme, les stages et les critères d’obtention du diplôme. Des entrevues de suivi avec des intervenants des programmes ont été menées pour vérifier ou clarifier les données. Les résultats mettent en évidence les incohérences qui existent entre les programmes de formation des futurs enseignants de FLS. Nous proposons des moyens par lesquels les facultés d’éducation canadiennes pourraient offrir une approche plus holistique de « parcours » pour recruter, préparer et retenir les nouveaux enseignants de FLS

Group-IV midinfrared plasmonics

The use of heavily doped semiconductors to achieve plasma frequencies in the mid-IR has been recently proposed as a promising way to obtain high-quality and tunable plasmonic materials. We introduce a plasmonic platform based on epitaxial n-type Ge grown on standard Si wafers by means of low-energy plasma-enhanced chemical vapor deposition. Due to the large carrier concentration achieved with P dopants and to the compatibility with the existing CMOS technology, SiGe plasmonics hold promises for mid-IR applications in optoelectronics, IR detection, sensing, and light harvesting. As a representative example, we show simulations of mid-IR plasmonic waveguides based on the experimentally retrieved dielectric constants of the grown materials

Processing and Damage Tolerance of Continuous Carbon Fiber Composites Containing Puncture Self-Healing Thermoplastic Matrix

Research at NASA Langley Research Center (NASA LaRC) has identified several commercially available thermoplastic polymers that self-heal after ballistic impact and through-penetration. One of these resins, polybutadiene graft copolymer (PB(sub g)), was processed with unsized IM7 carbon fibers to fabricate reinforced composite material for further evaluation. Temperature dependent characteristics, such as the degradation point, glass transition (T(sub g)), and viscosity of the PBg polymer were characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and dynamic parallel plate rheology. The PBg resin was processed into approximately equal to 22.0 cm wide unidirectional prepreg tape in the NASA LaRC Advanced Composites Processing Research Laboratory. Data from polymer thermal characterization guided the determination of a processing cycle used to fabricate quasi-isotropic 32-ply laminate panels in various dimensions up to 30.5cm x 30.5cm in a vacuum press. The consolidation quality of these panels was analyzed by optical microscopy and acid digestion. The process cycle was further optimized based on these results and quasi-isotropic, [45/0/-45/90]4S, 15.24cm x 15.24cm laminate panels were fabricated for mechanical property characterization. The compression strength after impact (CAI) of the IM7/pBG composites was measured both before and after an elevated temperature and pressure healing cycle. The results of the processing development effort of this composite material as well as the results of the mechanical property characterization are presented in this paper

Mid-infrared n-Ge on Si Plasmonic Based Microbolometer Sensors

The detection and amplification of molecular absorption lines from a chemical weapons simulant is demonstrated using plasmonic antennas fabricated from n-Ge epitaxially grown on Si. A free-standing Si0.25Ge0.75 microbolometer detector with n-Ge plasmonic antenna is demonstrated as an integrated mid-infrared plasmonic sensor

n-Ge on Si for Mid-Infrared Plasmonic Sensors

The detection and amplification of molecular absorption lines from a mustard gas simulant is demonstrated using plasmonic antennas fabricated from n-Ge epitaxially grown on Si. Approaches to integrated sensors will be presented along with a review of n-Ge compared to other mid-infrared plasmonic materials

Processing and Characterization of Carbon Nanotube Composites

Recent advances in the synthesis of large-scale quantities of carbon nanotubes (CNT) have provided the opportunity to study the mechanical properties of polymer matrix composites using these novel materials as reinforcement. Nanocomp Technologies, Inc. currently supplies large sheets with dimensions up to 122 cm x 244 cm containing both single-wall and few-wall CNTs. The tubes are approximately 1 mm in length with diameters ranging from 8 to 12 nm. In the present study being conducted at NASA Langley Research Center (LaRC), single and multiple layers of CNT sheets were infused or coated with various polymer solutions that included commercial toughened-epoxies and bismaleimides, as well as a LaRC developed polyimide. The resulting CNT composites were tested in tension using a modified version of ASTM D882-12 to determine their strength and modulus values. The effects of solvent treatment and mechanical elongation/alignment of the CNT sheets on the tensile performance of the composite were determined. Thin composites (around 50 wt% CNT) fabricated from acetone condensed and elongated CNT sheets with either a BMI or polyimide resin solution exhibited specific tensile moduli approaching that of toughened epoxy/ IM7 carbon fiber unidirectional composites