Doctor of Philosophy

dissertationSingle molecule trajectories of 1,1'-dioctadecyl-3,3,3'3'-tetramethylindocarbo -cyanine perchlorate (DiI) fluorophores diffusing on planar supported 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) lipid bilayers imaged through total internal reflection fluorescence (TIRF) microscopy at different temperatures are investigated. The spatial resolution limit for detecting molecular motion is evaluated by characterizing the apparent motion which arises from the limited signal-to-noise ratio (S/N) of imaged and simulated stationary DiI molecules. Statistical criteria for reliably distinguishing molecular motion from stationary molecules using F-test statistics, including the computation of local signal-to-noise ratios are then established and used for reliably detecting subdiffraction motion of DiI molecules on DMPC. The same single molecule tracking concept is used in investigating the temperature dependence of subdiffraction diffusional confinement of single Rhodamine 6G molecules in polymer brushes of poly (N-isopropylacrylamide), pNIPAAm, above and below its lower critical solution temperature (LCST) of 32 °C. Reliably distinguishing subdiffraction molecular motion from stationary events is crucial in validating the application of single molecule tracking experiment in probing nanometer-sized hydrophobic environments of polymer structure. A versatile and rapid sol-gel technique for the fabrication of high quality one-dimensional photonic bandgap materials was developed. Silica/titania multilayer materials are fabricated by a sol-gel chemistry route combined with dip-coating onto planar or curved substrate. A shock-cooling step immediately following the thin film heat-treatment process is introduced. The versatility of this sol-gel method is demonstrated by the fabrication of various Bragg stack-type materials with fine-tuned optical properties. Measured optical properties show good agreement with theoretical simulations confirming the high quality of these sol-gel fabricated optical materials. Finally, magnetic functionalization studies of sol-gel derived Co-ion doped titania thin films using superconducting quantum interference device (SQUID) magnetometry and an attempt to measure their magneto-optical properties using a home-built Faraday rotation setup are discussed. The experimental limitations in reliably measuring magnetization responses of these thin films are introduced and discussed in detail. The summary and outlook chapters summarize the scientific significance of each research project and briefly introduce ongoing research based on the work and the results presented in this dissertation

Risk and Farmers' Decisions to Farm Organically: The Case of Devon (UK)

Merged with duplicate record 10026.1/288 on 01.02.2017 by CS (TIS)Over the past few decades, the organic sector in most developed countries has flourished. Growth in the sector has been paralleled by a substantial amount of research on several arenas (sec Cobb et al. 1999; Robles et al. 2005; Jackson and Lampkin 2008; Lobley et al. 2009c; among others). Reasons for adopting organic farming have been studied in a variety of instances (Padel 2001a). Although there is a considerable body of evidence that supports the distinctly 'risky nature' of organic farming, our identification and understanding of how this nature affects farmers' decisions whether or not to farm organically are limited (see, for example, Lockeretz 1995; Duram 1999; Midmore et al. 2001; Baecke et al. 2002; Hattam 2006). It seems that there has been widespread acceptance of the hypothesis that organic farmers are more likely to be risk-takers compared to non-organic farmers. Similarly, the hypothesis that organic farmers with Non-Farming Backgrounds (NFBs) may have different attitudes towards risk has not been investigated yet through detailed empirical analysis. Accordingly, this thesis seeks to analyse the importance of farmers' willingness to take risk in organic farming in their decisions regarding the adoption of organic farming where it is assumed that there is a link between attitudes and behaviours. The thesis employs a variety of methods: a questionnaire; familiarisation; in-depth interviews; and secondary data. The findings of this thesis suggest that not all sources and types of risks associated with organic farming are differently perceived by non-organic and organic farmers. In Devon (i.e. the study area), more non-organic than organic farmers mentioned the existence of 'farm-related risks' and 'risks related to farmers' belief. Further, 'risks related to financial returns' were perceived to be of concern by non-organic farmers compared to their organic counterparts. On the other hand, other types and sources of risks associated with organic farming were equally perceived to be of concern by both groups. As expected, the recent risky environment of organic farming played a significant role in this respect (see also de Buck et al. 2001; Flaten et al. 2005). The wider environment was moreover the cause of greater concern regarding production, market and institutional risks (as opposed to personal ones) among organic farmers in Devon at the time of the questionnaire survey, when compared to the level of concern at the time of adoption. This shows that perceptions of types and sources of risks associated with organic farming arc subject to change across time (CRER 2002). Compared to their non-organic counterparts, organic farmers in Devon were willing to take risk in organic farming. With regard to risk in farming and to risk in general, more organic farmers expressed risk-taking attitudes than did their non-organic counterparts. Consequently, and based on the main reasons for adoption and non-adoption of organic farming, this thesis suggests that willingness to take risk in organic farming acts as an extremely significant trigger for the uptake of organic fam1ing. This in turn confirn1s what has been emphasised by many researchers (see Baecke et al. 2002; Acs et al. 2005; Serra et al. 2008; among others). It also suggests that investigations into people's behaviours and decisions in relation to a 'risky activity' should take into account their attitudes towards risk in that activity. This thesis, in common with other studies (e.g. Kaltoft 1999; Lobley et al. 2005), also shows evidence of heterogeneity among organic farmers. A small group of organic farmers in Devon from NFBs was in search of the 'good life' and wanted to produce public goods from organic farming. Although technical, market and institutional risks associated with organic farming were of concern to organic farmers from NFBs in this study, these farmers did not have distinct risk perceptions. In contrast, they had distinct attitudes towards risk in organic farming. More organic farmers from NFBs than organic farmers from Farming Backgrounds (FBs) were willing to take risk in organic farming. Finally. and in accordance with Morris and Potter's ( 1995) work, this thesis has placed 79% of surveyed farmers in Devon on a typology which reflects the fact that farmers are not homogeneous. The 'conditional non-organic farmers' and 'pragmatic organic farmers' in this typology may, with varying degrees of ease, switch between organic and nonorganic methods at any point in the future due to possible changes in their attitudes towards risk in organic farming. In contrast, the 'resistant non-organic farmers' and 'committed organic farmers" at the two extremes of this typology will very likely be resistant to changes in their current farming systems. Accordingly, a set of policy recommendations which may help to increase future organic adoption in the UK has been set forth.Damascus Universit

Review on Microbial Sources, Production, Purification and Potential Industrial Applications of Laccases

Laccase (EC 1.10.3.2) is a multicopper blue oxidase which are involved in the oxidation of a broad range of organic substrates, including phenols, polyphenols, anilines, and even certain inorganic compounds by a one-electron transfer mechanism. Laccases are widely distributed in bacteria, fungai, insects and higher plants. There are mainly two production techniques for cultivation of laccase such as submersed fermentation and solid- state fermentation. This paper briefly discuss the effect of carbon source, effect of nitrogen source, effect of inducers, effects of surfactants, effect of agitator, influence of metal ions and  use of agro-industrial waste in production medium. The paper also discussed the purification techniques such as ammonium sulphate precipitation for extraction purpose followed by dialysis and ion-exchange chromatography as well characterization techniques. Laccases are known to show application ranging from pharmaceutical industries to textile sector as well as in biosensor development. View Article DOI: 10.47856/ijaast.2021.v08i12.00

Characterization of dynamics and internal structure of a mixed-surfactant wormlike micellar system using NMR and rheometry

We use complementary experiments—proton NMR diffusometry and relaxometry, deuterium NMR lineshapes, and rheometry—to construct a comprehensive picture of the microscopic structure of a mixed-surfactant wormlike micellar system composed of a zwitterionic surfactant and an anionic surfactant in brine. In this system, at some surfactant concentrations, the time for micellar breaking and recombination sb is not small compared with the micellar reptation time sR, weakening the condition to obtain a stress relaxation function with just one relaxation time at long times. FromNMRrelaxometry, we determine the overlap concentration. Deuterium NMR spectral lineshapes indicate the presence of a wide angular distribution in the orientational order. NMR diffusometry and rheology probe different timescales and yield complementary information indicating polymer-like behaviour at the corresponding lengthscales. Via NMR, surfactant diffusion coefficients are seen to decrease with increasing diffusion time, consistent with restricted diffusion within a reptating micelle. At the same time, comparison of measurements with protonated and deuterated surfactants strongly suggests that the measured short and long time diffusion coefficients correspond to intra-micellar and micellar diffusion, respectively. Fitting the diffusion results to a simple model, the average end-to-end micellar distance is estimated to be in the 1 mm range and only weakly dependent on concentration. The water diffusion measurements, on the other hand, imply a high degree of water structuring at the micellar surface. We also find that the wormlike micelles obeyed simple polymer-like scaling behaviors, with a crossover from Zimm-like (diffusion) to Rouse-like (rheology) exponents

Transferts dans la craie : approche régionale : le Nord-Ouest du Bassin de Paris : approche locale : la carrière de Saint-Martin-le-Noeud

The Chalk aquifer is a complex and heterogeneous system associated with a wide range of porosity (matrix, fractures and karstic conduits). These characteristics lead to a high heterogeneity of transfer processes and speed (ranging between 10-8 m s-1 and several metres per day). Furthermore, the Chalk aquifer is overlaid by superficial layers (clay-with-flints, loess and clayey-sandy deposits) with varying thicknesses. The impact of these formations on groundwater flows in the unsaturated zone (UZ) is still poorly understood. The aim of this thesis was to study the hydrodynamics and geochemical characteristics of free Chalk groundwater and particularly the role of the UZ and superficial layers. The chosen approach consisted in studying the spatial and temporal variability of groundwater level, dripping water discharges and groundwater geochemistry and search for controlling factors of this variability and compare it to the characteristics of the UZ of Chalk, the superficial layers, the land use and the climate. This approach was implemented at two spatial scales: at the regional scale of the North-West of the Paris Basin, around the Bray anticlinal and at the local scale of the underground quarry of Saint-Martin-le-Nœud which is a particularly interesting site (area below 1 km2) giving access to both the water table and the UZ water. Effective rainfall (Peff), dripping water discharge and water level variation chronicles were analysed using signal processing methods. Groundwater geochemistry has been studied statistically and using natural (major ions, electric conductivity) and anthropic (pesticides) tracers. At Saint-Martin-le-Nœud, the nature and thickness of the UZ and the superficial layers have been investigated with a geophysical survey and three holes were dug in the fields above the quarry. The results showed at both spatial scales a relatively low temporal variability with low and smooth water table responses and long time between reload periods and dripping water arrival. At the regional scale, the temporal variations of groundwater geochemistry are low. At the local scale, the evolution of underground lakes water electric conductivity indicates that water mineralization displays relatively low temporal variations. However, NO3-, Cl- and SO42- concentrations in lakes water varied significantly during the study. The results also highlighted a strong spatial variability. Thus, at the regional scale, piezometric variations are very different from one borehole to the next. Similarly, in the quarry of Saint-Martin-le-Nœud, lakes water level and dripping water discharges are spatially heterogeneous. Water geochemistry also displays a strong spatial variability at both regional and local scales.L’aquifère de la craie est un milieu hétérogène complexe lié à une large gamme de porosités (matrice, fractures et conduits karstiques), entrainant une forte hétérogénéité des processus et des vitesses de transfert (de 10-8 m s-1 à plusieurs mètres par jour). De plus, l’aquifère de la craie est recouvert par des formations superficielles (argiles à silex, lœss et dépôts argilo-sableux) d’épaisseurs variables, dont l’influence sur les écoulements au sein de la ZNS est encore mal connue. Le but de cette thèse est d’étudier le fonctionnement hydrodynamique et géochimique des eaux souterraines libres de la craie, et en particulier le rôle de la ZNS et des formations superficielles. L’approche suivie a consisté à étudier la variabilité spatio-temporelle du niveau d’eau de la nappe, des débits de percolation et de la géochimie des eaux souterraines et à rechercher les facteurs de contrôle de cette variabilité en la croisant aux caractéristiques de la ZNS de la craie, des formations superficielles, de l’occupation des sols et du climat. Cette approche a été mise en place à deux échelles spatiales : à une échelle régionale au Nord-Ouest du Bassin de Paris, autour de l’anticlinal de Bray et à une échelle locale sur le site de la carrière souterraine de Saint-Martin-le-Nœud (site particulièrement intéressant de moins d’un km2, donnant accès aux eaux de la nappe et aux eaux provenant de la ZNS). Les chroniques de pluie efficace, de débit de percolation et de variation du niveau d’eau ont été analysées grâce à des méthodes de traitement du signal. La géochimie des eaux a été étudiée statistiquement et par l’utilisation de traceurs naturels (ions majeurs, conductivité électrique) ou anthropiques (pesticides). A Saint-Martin-le-Nœud, l’épaisseur et la nature de la ZNS et des formations superficielles ont été étudiées grâce à des méthodes géophysiques et par le creusement de trois fosses en surfaces de la cavité. Les résultats ont montrés pour les deux échelles spatiales (1) Une variabilité temporelle relativement faible : la réponse de la nappe et l’arrivée des eaux de percolation après une période de recharge sont lentes et tamponnées ; A l’échelle régionale, les variations temporelles de la géochimie sont faibles. A l’échelle locale, l’évolution de la conductivité électrique des eaux des lacs montre des variations temporelles de la minéralisation des eaux relativement lentes. Cependant, les concentrations en NO3-, Cl- et SO42- des eaux des lacs varient significativement. (2) Une variabilité spatiale très marquée : à l’échelle régionale, les variations piézométriques sont très différentes d’un forage à l’autre. De même, dans la cavité de Saint-Martin-le-Nœud, les variations du niveau des lacs et les flux de percolation diffèrent spatialement ; La géochimie des eaux présente également une forte hétérogénéité spatiale, que ce soit à l’échelle régionale ou locale

Design and Evaluation of a Novel Lens-Based SPECT System Based on Laue Lens Gamma Diffraction: GEANT4/GAMOS Monte Carlo Study

Abstract While improvements in SPECT imaging techniques constitute a significant advance in biomedical science and cancer diagnosis, their limited spatial resolution has hindered their application to small animal research and early tumour detection. Using recent breakthroughs established by the high-energy astrophysics community, focusing X-ray optics provides a method to overcome the paradigm of low resolution and presents the possibility of imaging small objects with sub-millimetre resolution. This thesis aims to tackle the constraints associated with the current SPECT imaging designs by exploiting the notion of focusing high energy photons through Laue lens diffraction and developing a means of performing gamma rays imaging that would not rely on parallel or pinhole collimators. The gradual development of the novel system is discussed, starting from the single, modular, and multi-Laue lens-based SPECT. A customized 3D reconstruction algorithm was developed to reconstruct an accurate 3D radioactivity distribution from focused projections. A plug-in implementing the Laue diffraction concept was developed and used to model gamma rays focusing in the GEANT4 toolkit. The plug-in will be incorporated into GEANT4 upon final approval from its developers. The single lens-based, modular lens-based and multi lens-based SPECT models detected one hit per 42 source photons (sensitivity of 790 ⁄), three hits per 42 source photons (sensitivity of 2,373 ⁄), and one hit per 20 source photons (sensitivity of 1,670 ⁄), respectively. Based on the generated 3D reconstructed images, the achievable spatial resolution was found to be 0.1 full width at half maximum (FWHM). The proposed design’s performance parameters were compared against the existing SIEMENS parallel LEHR and multi-pinhole (5-MWB-1.0) Inveon SPECT. The achievable spatial resolution is decoupled from the sensitivity of the system, which is in stark contrast with the existing collimators that suffer from the resolution-sensitivity trade-off and are limited to a resolution of 2 . The proposed system allows discrimination between adjacent volumes as small as 0.113 , which is substantially smaller than what can be imaged by any existing SPECT or PET system. The proposed design could lay the foundation for a new SPECT imaging technology akin to a combination of tomosynthesis and lightfield imaging

Relationship Between Dermatoglyphics And Cleft Lip And/Or Palate : A Review Of Literature.

El presente artículo revisa los conceptos asociados con los dermatoglifos tales como su clasificación, características y aplicaciones. Se revisan además las hendiduras orofaciales tales como el labio y paladar hendido y se propone una posible relación entre los dermatoglifos y estas hendiduras orofaciales, entidades que aunque se consideran aisladas en un principio, provienen del mismo tejido embrionario, el ectodermo, y su periodo de formación se da en las mismas semanas de gestación prenatal, haciendo que factores genéticos y medioambientales que influenciarían el desarrollo de el labio y/o paladar hendido asindrómico podrían reflejarse en las huellas dactilares y el tipo de patrón que siguen éstas. SUMMARY This article reviews the concepts associated with dermatoglyphs such as their classification, characteristics and applications. It also reviews orofacial clefts such as cleft lip and palate and proposes a possible relationship between dermatoglyphics and these orofacial clefts, entities that are considered isolated at first, but considering that they are derived from the same embryonic tissue, the ectoderm, and their development is in the same period of gestation, making genetic and environmental factors that would influence the development of the asyndromic lip and / or palate could be reflected in the fingerprints and the type of pattern that they follow

Monocular depth estimation for 2D mapping of simulated environments

This article addresses the problem of constructing maps for 2D simulated environments. An algorithm based on monocular depth estimation is proposed achieving comparable accuracy to methods utilizing expensive sensors such as RGBD cameras and LIDARs. To solve the problem, we employ a multi-stage approach. First, a neural network predicts a relative disparity map from an RGB flow provided by RGBD camera. Using depth measurements from the same camera, two parameters are estimated that connect the relative and absolute displacement maps in the form of a linear regression relation. Based on a simpler RGB camera, by applying a neural network and estimates of scaling parameters, an estimate of the absolute displacement map is formed, which allows to obtain an estimate of the depth map. Thus, a virtual scanner has been designed providing Cartographer SLAM with depth information for environment mapping. The proposed algorithm was evaluated on a ROS 2.0 simulation of a simple mobile robot. It achieves faster depth prediction compared to other depth estimation algorithms. Furthermore, maps generated by our approach demonstrated a high overlap ratio with those obtained using an ideal RGBD camera. The proposed algorithm can find applicability in crucial tasks for mobile robots, like obstacle avoidance, and path planning. Moreover, it can be used to generate accurate cost maps, enhancing safety and adaptability in mobile robot navigation

Compensation orthodontic treatment of an adult patient with bilateral cleft lip and palate clip. Case Report

Se presenta caso clínico de un paciente de 28 años de edad con labio y paladar hendido bilateral el cual fue realizado en la clínica de labio y paladar hendido del posgrado de ortodoncia de la Universidad del Valle en el periodo de 5 años y 4 meses. El paciente presentaba una relación esquelética Clase II, Prognatismo maxilar, macrognatismo severo mandibular, una maloclusión molar Clase I derecha y Clase II izquierda acompañada de retroinclinación severa y retrusión leve de incisivos superiores e inferiores al igual que malposiciones múltiples e Impactación del diente 12. Se desarrolló plan ortodóncico no quirúrgico de compensación, acompañado de un tratamiento inicial ortopédico de expansión maxilar y ortodóncico correctivomediante aparatología fija tipo brackets estándar slot 0.022x0.028 pulgadas, exodoncias de primeros premolares inferiores,tipificación de caninos como incisivos laterales, al igual que rehabilitación de los dientes anteriores superiores. Se obtuvo resultados satisfactorios en términos de una oclusión funcional y estética. SUMMARY Clinical case of a 28 year old patient with bilateral cleft lip palate, who was treated during a period of 5 years and 4 months, at the University of Valle postgraduate orthodontic’s clinic of lip and palate, is presented. The patient had undershot jaw, severe mandibular macrognatismo, molar malocclusionclass I and class II right and left, accompanied by severe recumbent and mild retrusión of upper incisors and lower and, multiple malposition and impaction tooth 12. A non - surgical orthodontic plan compensation was developed and accompanied by an initial mandibular treatment, orthopedic expansion and corrective orthodontic treatment, using fixed appliances such as standard braces slot 0.22x0.028 inches, extractions of lower first premolars, typing canines as lateral incisors as well as rehabilitation of the upper front teeth. Satisfactory results were obtained in terms of aesthetic and functional occlusion