Based on a study of existing solar filament and tracking methods, a fully automated solar filament detection and tracking method is presented. An adaptive thresholding technique is used in a segmentation phase to identify candidate filament pixels. This phase is followed by retrieving the actual filament area from a region grown filament by using statistical parameters and morphological operations. This detection technique gives the opportunity to develop an accurate spine extraction algorithm. Features including separation distance, orientation and average intensities are extracted and fed to a Neural Network (NN) classifier to merge broken filament components. Finally, the results for two consecutive images are compared to detect filament disappearance events, taking advantage of the maps resulting from converting solar images to Heliographic Carrington co-ordinates. The study has demonstrated the novelty of the algorithms developed in terms of them now all being fully automated; significantly the algorithms do not require any empirical values to be used whatsoever unlike previous techniques. This combination of features gives the opportunity for these methods to work in real-time. Comparisons with other researchers shows that the present algorithms represent the filaments more accurately and evaluate computationally faster - which could lead to a more precise tracking practice in real-time. An additional development phase developed in this dissertation in the process of detecting solar filaments is the detection of filament disappearances. Some filaments and prominences end their life with eruptions. When this occurs, they disappear from the surface of the Sun within a few hours. Such events are known as disappearing filaments and it is thought that they are associated with coronal mass ejections (CMEs). Filament disappearances are generally monitored by observing and analysing successive solar H-alpha images. After filament regions are obtained from individual H-alpha images, a NN classifier is used to categorize the detected filaments as Disappeared Filaments (DFs) or Miss-Detected Filaments (MDFs). Features such as Area, Length, Mean, Standard Deviation, Skewness and Kurtosis are extracted and fed to this neural network which achieves a confidence level of at least 80%. Comparing the results with other researchers shows high divergence between the results. The NN method shows better convergence with the results of the National Geophysical Data Centre (NGDC) than the results of the others researchers.

Septinas são proteínas que ligam GTP e interagem entre si formando heterocomplexos, os quais se organizam em filamentos e estruturas de maior nível de organização. Em humanos são encontrados 13 genes que codificam septinas, as quais se dividem em 4 grupos com base na similaridade de sua organização estrutural. Análises filogenéticas identificaram quatro septinas ortólogas no deuterostômio Ciona intestinalis, as quais apresentam, cada uma, identidade com um dos quatro grupos de septinas de mamíferos. Tais proteínas foram nomeadas CiSEPT2, CiSEPT6, CiSEPT7 e CiSEPT9 devido a identidade com as septinas humanas. Sabe-se que septinas de diferentes grupos interagem entre si formando heterocomplexos e, assim, a possibilidade de formar um oligômero único em C. intestinalis permite um modelo mais simples para o estudo da organização dos filamentos. Análises de bioinformática identificaram nessas proteínas motivos estruturais típicos de septinas, incluindo resíduos conservados para a ligação e hidrólise do GTP. As proteínas foram produzidas de forma heteróloga e a capacidade hidrolítica tanto de CiSEPT2 como de CiSEPT7 foiram confirmadas diretamente. Em contrapartida, CiSEPT6 não apresentou atividade catalítica. Um sistema de coexpressão foi construído no qual as quatro septinas de C. intestinalis foram co-expressas e co-purificadas em diferentes arranjos, resultando na formação de heterocomplexos parciais além daquele contendo as quatro subunidades. A avaliação do estado oligomérico dos heterocomplexos parciais mostrou que estes correspondem majoritariamente a tetrâmeros e hexâmeros quando formados, respectivamente, por duas ou três subunidades. Estes oligômeros foram analisados por microscopia eletrônica de transmissão (MET) em que se observou que os mesmos se dispõem na forma de um bastão. Ensaios ainda mostraram que a polimerização desses oligômeros é dependente de CiSEPT2 sugerindo que esta subunidade esteja possivelmente posicionada na extremidade do heterocomplexo. Adicionalmente, ensaios de polimerização realizados com o complexo CiSEPT2/6/7/9 revelaram que este é capaz de interagir com filamentos adjacentes, possivelmente via coiled-coil, formando estruturas de mais alta ordem, similar aos já observados em S. cerevisiae. Finalmente, experimentos utilizando termoforese em microescala (MST) mostraram uma maior afinidade de interação entre as subunidades quando oligômeros estão envolvidos, indicando que estes podem atuar como fator de nucleação para a formação dos heterocomplexos. Esse trabalho apresenta os primeiros estudos de caracterização das septinas de C. intestinalis mostrando a formação do heterocomplexo e representa um modelo simplificado e viável para estudos estruturais relativos a formação de filamentos de septinas. Assim, através de uma abordagem comparativa com complexos oriundos de outros organismos, este novo complexo poderá contribuir para a compreensão do mecanismo de montagem e controle da polimerização de septinas. / Septins are GTP-binding proteins that interact with each other forming heterocomplexes, filaments and higher order structures. The human genome encodes 13 septins, which are divided into 4 subgroups based on sequence similarity. Phylogenetic analysis demonstrated that only a single representative of each of these subgroups is present in the non-vertebrate chordate Ciona intestinalis. These proteins are named CiSEPT2, CiSEPT6, CiSEPT7 and CiSEPT9 due to their great similarity with human septins. Once septins from different subgroups are able to interact among themselves to form hetero-oligomeric complex, C. intestinalis representatives can be used as a simpler model for studies of septin complex assembly. Bioinformatics analysis identified typical structural motifs of septins in these proteins, including conserved residues for binding and hydrolysis of GTP. These septins were expressed and characterized biophysically and biochemically revealing that CiSEPT2 and CiSEPT7 are capable of hydrolyzing GTP. In contrast, CiSEPT6 showed no catalytic activity. A coexpression system were designed in which the four septins of C. intestinalis were co-expressed and co-purified in different arrangements, resulting the formation of partial heterocomplexes in addition to that containing the four subunits. The oligomeric state of the partial heterocomplexes were confirmed corresponding to tetramer and hexamers when formed, respectively, by two or three subunits. Transmission electron microscopy analysis revealed that these oligomers assemblies are rod-like structures. The polymerization of these oligomers is dependent on CiSEPT2 suggesting that this subunit occupies possibly the terminal positions of the heterocomplex. Additionally, polymerization assays performed with the CiSEPT2/6/7/9 complex revealed that it is capable of interacting with adjacent filaments, possibly via coiled-coil, forming higher order structures similar to those already reported in S. cerevisiae. Finally, the interaction strenght among C. intestinalis septins were determined using microscale thermoforesis (MST), revealing a higher binding affinity when titration involves small oligomers instead of monomers, indicating that these may act as a nucleating factor for heterocomplex assembly. This work constitutes the first characterization of C. intestinalis septins presenting the heterocomplex assembly and represents a simplified and potential model for structural studies regarding the filaments assembly of septins. Thus, comparative studies involving complexes from other organisms may contribute to the understanding of the assembly mechanism and polymerization control of septins.

abstract: ABSTRACT Programmable metallization cell (PMC) technology uses the mechanism of metal ion transport in solid electrolytes and electrochemical redox reactions to form metallic electrodeposits. When a positive bias is applied from anode to cathode, atoms at the anode are oxidized to ions and dissolve in the solid electrolyte. They travel to the cathode under the influence of an electric field, where they are reduced to form electrodeposits. These electrodeposits are filamentary in nature and grow in different patterns. Devices that make use of the principle of filament growth have applications in memory, RF switching, and hardware security. The solid electrolyte under investigation is tungsten trioxide with copper deposited on top. For a standard PMC, these layers are heated in a convection oven to dope the electrolyte. Once the heating process is completed, electrodes are deposited on top of the electrolyte and biased to grow the filaments. What is investigated is the rate of dendritic growth to applied field on the PMC and the composition of the electrolyte. Also investigated are modified three-terminal PMC capacitance change devices. These devices have a buried sensing electrode that senses the increasing capacitance as the filaments grow and increase the upper electrode area. The rate of dendritic growth in the tungsten trioxide and copper electrolyte of different chemistries and applied field to the PMC devices is the important parameter. The rate of dendritic growth is related to the change of capacitance. Through sensing the change in capacitance over time the modified PMC device will function as an odometer device that can be attached to chips. The attachment of these devices to chips, help in preventing illegal recycling of old chips by marking those chips as old. This will prevent would-be attackers from inserting modified chips in systems that will enable them to by-pass any software security precautions. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2019

Le Radiohéliographe de Nançay, rénové en 1996, est un instrument dédié à l'étude de l'activité sporadique de la couronne solaire, dans le domaine métrique et décimétrique. Les structures calmes de la couronne peuvent être également observées par l'utilisation de la synthèse d'ouverture, qui autorise la cartographie de structures à faible contraste.<br /><br />Je présente dans cette thèse les premiers résultats de synthèse d'ouverture pour l'instrument rénové, en m'intéressant tout particulièrement à la contrepartie radio des filaments solaires, jamais étudiée auparavant dans cette gamme de longueur d'onde. Je montre que les observations sont explicables par la présence d'une cavité coronale autour des filaments, et que la radio permet son observation directe sur le disque.<br /><br />Je décris enfin trois cas de Disparitions Brusques de filament montrant, pour la première fois en radio, les stades initiaux du développement d'éruptions de filaments et de CMEs sur le disque, sous l'aspect des émissions thermiques. Ce travail s'appuie fortement sur les observations multi longueurs d'onde, rendues possibles par l'existence du satellite SOHO sur toute la période, et notamment son télescope EIT, et son coronographe LASCO.

It is well known that ultrashort, high intensity pulses with peak powers exceedinga certain critical value (Pcr) undergo self-focusingleading to collapse and filamentation. During the initial stagesof propagation at low intensities the beamdynamics are dominated by diffraction and dispersion. During filamentation, self-focusing resulting from the nonlinear Kerr effect is balanced by higher order nonlinearities such as plasma induced defocusing and absorption.This work examines the role that linear processes combined with initial spatial and temporal conditioningplay in the generation and subsequent evolution of filaments within nonlinearbeams. It is demonstrated that, because of linear diffraction, initial spatial beam shaping can have a dramatic effect on the filament pattern, the number of filaments and the energy contained in each filament. These ideas are applicable to cases that arequite common, such as circularly apodized beams, and help to explain interestingbehavior observed in these types of beams. Finally, it is demonstrated thatwith appropriate preconditioning of multiple subcritical pulses, linear effects can be employed to accurately control when and where filamentation occurs during long distance propagation through conditional collapse of overlapping pulses.

Intermediate filaments are fibrous proteins, appearing in a wide variety of tissue specific forms. The function of these proteins is poorly understood, although they are commonly believed to perform a structural role in the cell. Evidence suggests that the role these proteins play may be more dynamic than was previously believed. To gain more insight into their normal in vivo function, a single-chain monoclonal antibody has been constructed to serve as a specific reagent which can disrupt the intermediate filament network in vivo. The work presented in this thesis represents the first step in an approach which involves the use of single-chain monoclonal antibodies as specific reagents to target and disrupt the function of intracellular proteins. / The polymerase chain reaction was used for the cloning and modification of the heavy and light chain variable regions of the murine monoclonal antibody produced by the TIB 131 hybridoma. The variable regions of the light and heavy IgG chains were initially amplified from cDNA using degenerate 5$ sp prime$ primers and 3$ sp prime$ primers complementary to the constant region of the appropriate chain. The amplification products were cloned individually, sequenced, then modified to include restriction sites suitable for cloning into an expression vector. The two modified variable regions were cloned into an expression vector, and when expressed in either bacteria or in a rabbit reticulocyte lysate system, yielded a protein of the expected molecular weight.

This study comprised three questions, each posed with the intention of exploring the expression of the neurofilament protein (NF) and mRNA levels in the monkey lateral geniculate nucleus (LGN) and visual cortex. (1) Literature indicates NFs are differentially expressed across the two visual pathways that originate from magnocellular and parvocellular layers in LGN. The results herein suggest that this difference continues at the level of gene transcription for the neurofilament heavy gene. (2) NF expression, assessed by SMI-32 (an antibody that recognizes an epitope of the non-phosphorylated NFs), was investigated as a function of developmental changes occurring during the critical period in area V1 of the vervet monkey visual cortex. The findings indicate that the M pathway develops before the P pathway. (3) The effect of eye enucleation on long-term changes in NF expression was investigated. The results do not support the idea that NF are activity-dependent.

No description available.

Thesis (Ph. D.)--University of Hong Kong, 2007. / Title proper from title frame. Also available in printed format.

Thesis (Ph.D.) - University of Queensland, 2003. / Includes bibliography.