MATCHED ARCHITECTURES FOR SIGNAL PROCESSING AND CONTROL

Fast processing environments for real-time data acquisition, data processing and control applications may be realised using very different architectures. State of the art systems generally employ multiprocessors and parallel processing having a dedicated architecture such as systolic arrays to support computation-intensive signal processing tasks such as, for instance, convolution, filtering, FFT. etc. Mostly, general purpose rather than application driven architectures are used whenever possible and the available literature is heavily concentrated on the first configuration. At TPD-TNO, the research emphasis is on application driven architectures. and the objectives for the so-called 'matched' architecture designs are: - Capability for a wide range of sizes, starting from small systems. The objective here is design for scalability - Design for systems to be used in harsh environments - Design for minimum connectivity. reduced communication bandwidth, incorporation of dedicated preprocessing. multibus systems, etc. The real-time behaviour of general purpose architectures is not sufficiently predictable and they are not designed to perform acquisition tasks or data-intensive processing with high performance. Matched architectures, on the contrary, are designed for well defined applications and optimized for each application, The key effort in matched architecture research is directed towards efficiently mapping algorithms to processing steps in hardware (and software) architectures. Essentially. the design process is iterative

High-resolution transmission electron microscopy with an electrostatic Zach phase plate

A new method to control lattice-fringe contrast in high-resolution transmission electron microscopy (HRTEM) images by the implementation of a physical phase plate (PP) is proposed. PPs are commonly used in analogy to Zernike PPs in light microscopy to enhance the phase contrast of weak-phase objects with nm-sized features, which often occur in life science applications. Such objects otherwise require strong defocusing, which leads to a degradation of the instrumental resolution and impedes intuitive image interpretation. The successful application of an electrostatic Zach PP in HRTEM is demonstrated by the investigation of single crystalline Si and Ge samples. The influence of the Zach PP on the image formation process is assessed by analyzing the amplitudes of (111) reflections in power spectra which show a cosine-type dependence on the induced phase shift under certain conditions as predicted by theory

Improving the research culture at historically black universities: The situation at the University of the North

An important part of the transformation of higher education in South Africa concerns the professionalisation of historically black universities (HBUs). A vital element in this process forms the enhancement of a research culture that was hardly alive at these universities during the apartheid era. In this article experiences at the University of the North will be discussed, especially with reference to the supervision of postgraduate students. Problems students encounter are, for instance, poor guidance during the process of proposal writing, lack of supervisors with research experience and communication problems. After an inventory of existing problems of students and staff, as well as a reflection on specific experiences made in the UNIN programme of adult education, the way forward will be outlined on the level of disciplines/programmes, the level of schools and the level of university management. The establishment of research programmes, intensive training of supervisors, co-supervision, public defence of Master's and PhD dissertations, enhancement of the special position of postgraduate students and the improvement of the work-ethic of academic staff members are among the proposed solutions

Implication des voies de réponse aux stress à l'origine de la surproduction du TNF-a dans l'anémie de Fanconi

L anémie de Fanconi (AF) est un syndrome génétique humain rare caractérisé par une anémie aplasique progressive qui touche tous les éléments du système hématopoïétique, et par une prédisposition élevée aux cancers. Afin de mieux cerner les altérations cellulaires et moléculaires de l AF, nous avons comparé le profil transcriptionnel de cellules AF à celui de leurs dérivées corrigées et montré une dérégulation de l expression de gènes codant des protéines impliquées dans la réponse inflammatoire. Or, une surproduction de TNF- , acteur majeur de cette réponse, est décrite in vivo et in vitro dans l AF. De par ses activités, cette cytokine pourrait avoir un rôle majeur dans l étiologie de l AF, notamment dans la défaillance hématologique. En recherchant les origines de cette surproduction, j ai montré 1) la surexpression de la MMP-7, protéine capable de cliver le TNF- à la membrane conduisant ainsi à sa libération plus importante, 2) l hyperactivation des voies NF- B et MAPK (ERK, JNK, p38), 3) le contrôle par la voie ERK de la surexpression de la MMP-7, 4) l accumulation intracellulaire d espèces réactives de l oxygène (ROS). Ces résultats mènent à l établissement d un modèle moléculaire selon lequel l absence d un gène de l AF induit, probablement via l accumulation de ROS, un stress cellulaire qui aboutit à l activation des voies NF- B et MAPK et à la surproduction du TNF- . Cette surproduction pourrait en retour exacerber cet état de stress. Les altérations moléculaires observées dans les voies de réponse aux stress apportent un éclairage nouveau sur l AF et permettent d envisager de nouvelles approches thérapeutiques.Fanconi anemia (FA) is a rare genetic disorder characterized by a progressive bone marrow failure that affects all blood cell lineages, and by an increased cancer susceptibility. In order to improve our understanding of the cellular and molecular abnormalities in FA, we compared the transcription profile of FA cells to their ectopically corrected counterparts. We showed a deregulation in the expression of genes coding for proteins involved in the inflammatory response. Overproduction of TNF- which is a major mediator of this response has been reported both in vivo and in vitro in FA. In light of its activities, this cytokine could have a major role in FA etiology, particularly in the progressive bone marrow failure. By investigating the molecular origins of this overproduction, I showed 1) that overexpression of MMP-7, which is able to produce a correctly processed TNF- , is responsible for the high rate of TNF- shedding and release from the cytoplasmic membrane, 2) an overactivation of NF- B and MAPK (ERK, JNK, p38) pathways, 3) that ERK pathway is the main responsible for MMP-7 overexpression, 4) an accumulation of reactive oxygen species (ROS). These results lead to the establishment of a molecular model in which FA gene products loss of function induces a cellular stress, maybe via ROS accumulation, which could result in activation of NF- B and MAPK pathways and TNF- overproduction. This overproduction could, in turn, exacerbate this state of stress. The reported overactivation of the stress-signaling pathways provides further insights into this disease and may represent an experimental support for the development of new therapeutic approaches.PARIS-BIUSJ-Thèses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF