Several mechanisms have been proposed to explain the process of vein pattern formation in plant tissues. The most widely accepted amongst biologists is the canalization hypothesis, derived from pea root and stem experiments. According to this hypothesis, a signal, thought to be the phytohormone auxin, is transported polarly from cell to cell from the shoot to the root and is canalized progressively into narrow channels of high auxin fluxes that later differentiate to become vascular tissue. In this project, we set out to test whether auxin canalization drives vein pattern formation, using Arabidopsis thaliana mutants with increased auxin transport (max4-1, max3-9, max2-1 and max1-1). We predicted that the mutants would have distinct vein patterns and especially different angles between the primary and secondary veins, compared to the wild type. First rosette leaves of 15 plants per genotype were harvested for analysis each day from 7 to 17 days after sowing, giving a total of eight hundred twenty-five leaf samples to analyze. Venation patterns were extracted and analyzed using custom-made software written with Matlab. Overall, compared with the wild type, mutants with the highest auxin transport (max4-1 and max3-9) had different vein patterns at early developmental stages, confirming a role for auxin transport in vein patterning. However, veins of mutants and wild type connected at similar angles, which is not consistent with the auxin canalization hypothesis, as originally formulated.

Several mechanisms have been proposed to explain the process of vein pattern formation in plant tissues. The most widely accepted amongst biologists is the canalization hypothesis, derived from pea root and stem experiments. According to this hypothesis, a signal, thought to be the phytohormone auxin, is transported polarly from cell to cell from the shoot to the root and is canalized progressively into narrow channels of high auxin fluxes that later differentiate to become vascular tissue. In this project, we set out to test whether auxin canalization drives vein pattern formation, using Arabidopsis thaliana mutants with increased auxin transport (max4-1, max3-9, max2-1 and max1-1). We predicted that the mutants would have distinct vein patterns and especially different angles between the primary and secondary veins, compared to the wild type. First rosette leaves of 15 plants per genotype were harvested for analysis each day from 7 to 17 days after sowing, giving a total of eight hundred twenty-five leaf samples to analyze. Venation patterns were extracted and analyzed using custom-made software written with Matlab. Overall, compared with the wild type, mutants with the highest auxin transport (max4-1 and max3-9) had different vein patterns at early developmental stages, confirming a role for auxin transport in vein patterning. However, veins of mutants and wild type connected at similar angles, which is not consistent with the auxin canalization hypothesis, as originally formulated.

The main idea of current PhD thesis is an accuracy analysis of testing and calibration of geodetic instruments. The object of investigation is an analysis of means and methods for testing and calibration of geodetic instruments for plane angle measurement, development of such calibration equipment, its accuracy investigation and the research of its accuracy increasing possibilities. These objects are important for successful testing or calibration of geodetic instruments for angle measuring which is essential in ensuring the precision of measurements taken in surveying, construction, mechanical engineering, etc. There are several main goals of the presented work. First one is an analysis of the angle measuring methods and devices suitable for the testing and calibration of geodetic instruments, according to the results of the mentioned analysis the second task can be formulated – creation of a multi-reference plane angle testing and calibration equipment at Institute of Geodesy, Vilnius Gediminas Technical University and investigate the parameters of its accuracy. The third task is to investigate the accuracy increasing possibilities of the equipment, and implementation some of them into the practice. The thesis consists of four chapters, introduction, conclusions, list of references and appendixes. Introduction is dedicated for an introduction to the problem and its topicality. There are also formulated purposes and tasks of the work; the used methods and novelty of... [to full text] / Disertacijoje nagrinėjamos geodezinių kampus matuojančių prietaisų patikros bei kalibravimo metodai bei priemonės. Pagrindinis tyrimo objektas yra geodezinių prietaisų tikslumo parametrų matavimo būdų ir priemonių analizė, kalibravimo įrenginio kūrimas, jo tikslumo charakteristikų tyrimas bei įrenginio tobulinimas. Šie objektai yra svarbūs vykdant geodezinių prietaisų kalibravimą, kas savo ruožtu yra labai svarbu užtikrinant reikiamą šių prietaisų matavimų tikslumą geodezijoje, statybose, mašinų gamyboje ir t. t. Pagrindinis disertacijos tikslas – geodezinių kampų matavimo prietaisų kalibravimo galimybių analizė ir sukurto kalibravimo įrenginio tikslumo para¬metrų tyrimas. Darbe sprendžiami keli pagrindiniai uždaviniai: plokščiųjų kampų mata¬vimo metodų bei įrenginių, tinkamų geodeziniams prietaisams kalibruoti, analizė; daugiaetalonio kampų kalibravimo stendo kūrimas Vilniaus Gedimino technikos universiteto Geodezijos institute bei jo tikslumo charakteristikų tyri¬mas; stendo tikslumo didinimo galimybių bei priemonių tyrimas, ir apskri¬timinių skalių kalibravimo būdų tobulinimas. Disertaciją sudaro šeši skyriai, įvadas, išvados, literatūros sąrašas bei priedai. Įvade nagrinėjamas problemos aktualumas, formuluojamas darbo tikslas bei uždaviniai, aprašomas mokslinis darbo naujumas, pristatomi autoriaus pranešimai ir publikacijos, disertacijos struktūra. Pirmasis skyrius skirtas labiausiai paplitusių plokščiųjų kampų matavimo būdų bei priemonių tinkamų geodeziniams prietaisams... [toliau žr. visą tekstą]

Several mechanisms have been proposed to explain the process of vein pattern formation in plant tissues. The most widely accepted amongst biologists is the canalization hypothesis, derived from pea root and stem experiments. According to this hypothesis, a signal, thought to be the phytohormone auxin, is transported polarly from cell to cell from the shoot to the root and is canalized progressively into narrow channels of high auxin fluxes that later differentiate to become vascular tissue. In this project, we set out to test whether auxin canalization drives vein pattern formation, using Arabidopsis thaliana mutants with increased auxin transport (max4-1, max3-9, max2-1 and max1-1). We predicted that the mutants would have distinct vein patterns and especially different angles between the primary and secondary veins, compared to the wild type. First rosette leaves of 15 plants per genotype were harvested for analysis each day from 7 to 17 days after sowing, giving a total of eight hundred twenty-five leaf samples to analyze. Venation patterns were extracted and analyzed using custom-made software written with Matlab. Overall, compared with the wild type, mutants with the highest auxin transport (max4-1 and max3-9) had different vein patterns at early developmental stages, confirming a role for auxin transport in vein patterning. However, veins of mutants and wild type connected at similar angles, which is not consistent with the auxin canalization hypothesis, as originally formulated.

Extensive research has been performed on the interaction of dithiocarbonates (xanthate) with a wide variety of substrates. This study the focuses on the interaction of trithiocarbonates (TTC) with pyrite and copper. The mechanism of adsorption of the xanthate is compared to that of the TTC. For the xanthate to adsorb it is necessary for an oxidant to be present, since xanthate adsorbs via charge transfer processes (electrochemical processes). It was found by the use of cyclic voltammetry and contact angle measurements that collector adsorption of the TTC can occur in both oxidising and reducing (thus the absence of an oxidant) conditions. Neither the TTC monomer nor the dimer could be detected on the surface by the use of Raman spectroscopy. The collector species on the surface was the TTC decomposition products namely the thiol or thiolate. Electrochemical impedance spectroscopy (EIS) confirmed that the TTC can interact under oxidising and reducing conditions. EIS showed that the rate of adsorption of the collector species for anodic currents increases relatively to the rate of adsorption for cathodic currents. Different adsorption mechanisms are realised for the different polarisation conditions. It is postulated that the TTC species serves as an intermediate for the adsorption of the thiol or thiolate on the surface, ultimately rendering the surface hydrophobic. Decomposition tests, performed by employing UV/Vis spectroscopy, indicated that the TTC is very unstable between a pH of 4 and 11. The thiol or thiolate however does not readily adsorb onto the substrates (indicated by the EIS measurements). Microflotation tests confirmed the thiolate’s inability to render pyrite hydrophobic. The microflotation tests also indicated that the TTC became less effective in recovering pyrite after it was left to decompose for a couple of hours. / Dissertation (MSc (Metallurgy))--University of Pretoria, 2008. / Materials Science and Metallurgical Engineering / unrestricted

Several mechanisms have been proposed to explain the process of vein pattern formation in plant tissues. The most widely accepted amongst biologists is the canalization hypothesis, derived from pea root and stem experiments. According to this hypothesis, a signal, thought to be the phytohormone auxin, is transported polarly from cell to cell from the shoot to the root and is canalized progressively into narrow channels of high auxin fluxes that later differentiate to become vascular tissue. In this project, we set out to test whether auxin canalization drives vein pattern formation, using Arabidopsis thaliana mutants with increased auxin transport (max4-1, max3-9, max2-1 and max1-1). We predicted that the mutants would have distinct vein patterns and especially different angles between the primary and secondary veins, compared to the wild type. First rosette leaves of 15 plants per genotype were harvested for analysis each day from 7 to 17 days after sowing, giving a total of eight hundred twenty-five leaf samples to analyze. Venation patterns were extracted and analyzed using custom-made software written with Matlab. Overall, compared with the wild type, mutants with the highest auxin transport (max4-1 and max3-9) had different vein patterns at early developmental stages, confirming a role for auxin transport in vein patterning. However, veins of mutants and wild type connected at similar angles, which is not consistent with the auxin canalization hypothesis, as originally formulated.

The present thesis concerns with a few investigations on sensing/measurement of small angle rotation/tilt using Pattern Imaging Method. The methodology involves looking at the tailored-objects located adjacent to the observer (CCD camera) through a mirror and extracts the angular position of the mirror from their images by processing the latter through object specific algorithm. Its principal advantage stems from the fact that small-angle measurement can be done using ambient light which is neither collimated nor filtered for single wavelength. This makes the associated optical configuration not only simple but also robust for the said application, in comparison to currently competing technologies based on Autocollimation and Interferometry. The present thesis elaborates specifically four new Pattern-Designs proposed for tailoring the spatial-brightness of the objects. Introducing for the first time, processing algorithms based on ‘Modified Fringe-Processing Strategy’ and ‘Phase-Only-Correlation’, the investigations demonstrate enhanced performance for small angle measurement with all the proposed pattern designs. The first three designs for the pattern are evaluated for 1-D measurement through fringe processing approach while the fourth pattern design is evaluated for 2-D measurement through Phase-only-Correlation. The results of the investigations are utilized to propose, design and develop a novel optical inclinometer which can work with any of the proposed pattern designs as the object. The first three pattern-designs rely upon sinusoidal modulation of the object surface and utilize three custom developed algorithms -Algorithm-A, Algorithm-B and Algorithm-C -to extract two quantities namely wrapped phase Δαw and unwrapped phase Δαuw , from the captured images. Each of these quantities will have an associated measurement range and accuracy corresponding to any of the three pattern designs. All measurements are carried out keeping the object/camera to mirror distance constant at 250 mm. From wrapped phase measurement, all the three designs, each with pitch of 2mm for sinusoidal modulation and held at a distance of 250 mm from the mirror, have been found to facilitate reliable angle measurement over a range of 850 arc seconds with accuracy better than 1 arc second after curve fitting the experimentally obtained data. From unwrapped phase measurement, the color coded as well as BCD coded composite patterns, when tested using five bands of sinusoidal modulation (with a pitch of 2mm) and held at a distance of 250 mm from the mirror, facilitated reliable angle measurement over a larger range of nearly 10 . The 2-D angle measurement using fourth pattern-design and the Algorithm-D, facilitated measurement over a range of 10 with an accuracy of 9 arc seconds when the distance between the mirror and the pattern is held at 250 mm. A comparison of the results from the present investigation with the best performance from other investigators reveals the following. The proposed modifications in the processing algorithms as well as the pattern designs help to achieve a measurement range of 750 arc seconds with accuracy better than 1 arc second from this method, with an object pattern whose lateral size is smaller by a factor of nearly 15. Such a size reduction in the object as well as the associated mirror would help to construct angle measuring instruments that work on this method more compactly. The results of the investigation have been utilized to propose and demonstrate a novel prototype optical inclinometer which has been experimentally found to work in a range of 0.40 with accuracy nearly 6 arc seconds.

‘Optical Caustics’ represent some of the most visually striking patterns of the light in nature.They occur when light rays from a source, such as the sun, get refracted, or reflected by curved media so as to bend and alter their path. They are ubiquitous and signify the regions of space in which many rays intersect to form bright singularities along a two-or a three-dimensional surface. The associated 2-D patterns (caustic patterns) could be simple or complex in ‘shape and size’ depending upon the optical arrangement used to produce them. Such patterns exhibit either a static or a dynamic behavior which can be controlled sensitively by the medium or the device used to produce them. The present thesis concerns with a few novel contributions in utilization of such optical caustics for the measurement of small angular rotation/tilt of objects. Utilizing a ‘hollow cylinder’ as a novel device for the generation of the optical caustics, the author proposed and demonstrated three new schemes of realizing a position-dependent-behavior of ‘Optical Caustic Patterns’. The said behavior is investigated both analytically as well as experimentally. The results of the investigation are then utilized to propose and demonstrate three methods of magnifying angular displacement of the hollow cylinder. The salient feature of the principle behind each of the said methods is illustrated in the figures below. The patterns in each of the above pictures correspond to two different positions of the hollow cylinder-the pattern in white color corresponds to the initial position while that in red color corresponds to new angular position of the cylinder. Defining S1 = ƒ (LΔΦ), S2= ƒ(TΔΦ) and S3= ƒ(ξ ΔΦ) as new signals from the proposed methods, it has been shown that each of them represent a magnified measure of the change in the angular position of the cylinder ΔΦ. Further, if a plane mirror is used in place of cylinder in the proposed methods, the corresponding signal S for the same change in the angular position ΔΦis represented by ΔD. For a chosen set of the experimental conditions, it is shown that for unit change in ΔΦ, the values of S1, S2 and S3 change 30, 37 and 62 times faster than ΔD. The investigations clearly demonstrate that hollow cylinders can be advantageously used as position-magnifying angle-sensing devices. The results of the investigations also suggest that in application areas such as auto collimation, torsion pendulum and design of motion control stages, this device is expected to bring in new advances.

<p>Abstract</p><p>The aim of the present study was to increase the understanding of how the cell surface properties affect the performance of unit operations used in primary protein purification. In particular, the purpose was to develop, set up and apply methods for studies of cell surface properties and cell interactions.</p><p>A method for microbial cell surface fingerprinting using surface plasmon resonance (SPR) is suggested. Four different <em>Escherichia coli </em>strains were used as model cells. Cell surface fingerprints were generated by registration of the interaction between the cells and four different surfaces, with different physical and chemical properties, when a cell suspension was flown over the surface. Significant differences in fingerprint pattern between some of the strains were observed. The physical properties of the cell surfaces were determined using microelectrophoresis, contact angle measurements and aqueous two-phase partitioning and were compared with the SPR fingerprints. The generated cell surface fingerprints and the physical property data were evaluated with multivariate data analysis that showed that the cells were separated into individual groups in a similar way using principal component analysis plots (PCA).</p><p>Studies of the behaviour of the model cells on stirred cell filtration and in an interaction test with different expanded bed adsorption (EBA) adsorbents were performed. It could be concluded that especially one of the strains behaved differently. Differences in the properties of the model cells were indicated by microelectrophoresis and aqueous two-phase partitioning which to some extent correlated with observed differences in behaviour during filtration and in an interaction test with EBA adsorbents.</p><p>The impact of high-pressure homogenisation of <em>E. coli </em>cell extract was examined, with a lab scale and a pilot scale technique. The DNA-fragmentation, visualised with agarose gel electrophoresis, and the resulting change in viscosity was analysed. A short homogenisation time resulted in increased viscosity of the process solution that correlated with increased concentration of released non-fragmented DNA. With longer homogenisation time the viscosity decreased with increasing degree of DNA-fragmentation.</p><p>The results show that strain dependant cell surface properties of<em> E. coli</em> may have an impact on several primary steps in downstream processing.</p>

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