Buffer insertion is an essential technique for reducing interconnect delay in submicron circuits. Though it is a well researched area, there is a need for robust and effective algorithms to perform buffer insertion at the circuit level. This thesis proposes a new buffer insertion algorithm for large circuits. The algorithm finds a buffering solution for the entire circuit such that buffer cost is minimized and the timing requirements of the circuit are satisfied. The algorithm iteratively inserts buffers in the circuit improving the circuit delay step by step. At the core of this algorithm are very simple but extremely effective techniques that constructively guide the search for a good buffering solution. A flexibility to adapt to the user's requirements and the ability to reduce the number of buffers are the strengths of this algorithm. Experimental results on ISCAS85 benchmark circuits show that the proposed algorithm, on average, yields 36% reduction in the number of buffers, and runs three times faster than one of the best known previously researched algorithms.

Thèse de 3e cycle : Sciences économiques : Lyon 2 : 1985. / Titre provenant de l'écran-titre.

Thesis (Ph. D.) -- California Institute of Technology, 2010. / Title from home page (03/01/2010). Advisor and committee chair names found in the thesis' metadata record in the digital repository. Includes bibliographical references.

Cyanobacteria are globally widespread and ecologically highly significant photoautotrophic microorganisms, with diverse geno- and phenotypic characters unprecedented among prokaryotes. This phylum embraces representatives with an exclusive adaptability in highly specialized environments, from oligotrophic ocean waters to the interior of cells in symbiotic plants, the most extreme being the chloroplasts. Insertion sequences (ISs) are short (~1000 bp) mobile genetic elements prevalent in microbial genomes, potentially representing potent adaptive forces. In this thesis, hypotheses tested that ISs play significant roles in both reductive and adaptive evolution in physiologically versatile cyanobacteria, using two model systems. First, the genome of an obligate plant (Azolla) symbiont, the cyanobacterium ‘Nostoc azollae 0708’, was sequenced, which led to the discovery of a highly ‘eroding’ genome (5,48 Mbp), loaded with ISs covering 14% of the genome, a situation likely caused by the relaxed selection pressure within the plant. The ISs were located in close proximity to the extremely numerous pseudogenes identified, although genes with key functions in a symbiotic context escaped IS mediated erosion (e.g. nitrogen fixation and differentiation genes). Some ISs were shown to have transposed short distances within the genome (‘local hoping’), and to be likely causative agents in pseudogene formation, and thus pivotal actors in the reductive evolution discovered. To widen the scope of ISs further, additionally 66 phylogenetically diverse microorganisms with a variety of life styles (free-living, symbionts, pathogens) were examined in regards to ISs influence. The data verified their over-all importance in shaping microbial genomes. Finally, natural microbial populations in the Baltic Sea, a semi-enclosed geologically young (~10,000 years) brackish water body offering steep gradients in salinity and nutrient loads, were examined using metatranscriptomics and metagenomics. A large proportion of the metagenome was devoted to ISs and most importantly a large fraction of the metatranscriptome consisted of IS transcripts (~1%), which may be suggestive of a high IS activity. These phenomena were most apparent in cyanobacteria in central parts of the Baltic Sea. The presence of an especially rich abundance of ISs in brackish waters was further substantiated by their low frequency (&lt; 0.1%) in microbes of marine waters. Hence, ISs may facilitate both adaptations (short term) and adaptive evolution (long term) in microbes entering brackish water, otherwise unable to cross the distinct limnic-to-marine salinity-divide. Together, the data reveal high genomic loads of ISs in cyanobacteria subject to highly demanding conditions and stress the importance of locally migrating ISs (and pseudogenization) as important facilitators in adaptation and evolution, being a more rapid process than hitherto expected. The findings strongly support current theories stating a crucial role of ISs in shaping microbial genomes to render fitness. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 3: Manuscript.</p>

Thèses (M.A.)--Université de Sherbrooke (Canada), 1997. / Titre de l'écran-titre (visionné le 20 juin 2006). Publié aussi en version papier.

Thèses (M.A.)--Université de Sherbrooke (Canada), 2000. / Titre de l'écran-titre (visionné le 20 juin 2006). Publié aussi en version papier.

Thèses (M.A.)--Université de Sherbrooke (Canada), 2001. / Titre de l'écran-titre (visionné le 20 juin 2006). Publié aussi en version papier.

La plupart des immigrants étrangers qui tentent d'intégrer le marché du travail au Canada vont connaître une trajectoire impliquant diverses contraintes. Cette étude qualitative se penche sur la problématique de l'insertion en emploi des immigrants francophones hors Québec. Elle est réalisée par le biais d'entrevues auprès de douze immigrants haïtiens dans la région Ottawa-Gatineau et vise à identifier les obstacles d’intégration en emploi et les stratégies de contournement employées par les immigrants tout au long de leur trajectoire respective. Il s'agit d'examiner comment les éléments du capital humain, du capital social et de la discrimination peuvent influencer leur insertion en emploi. Suite aux données recueillies dans nos entrevues nous avons déterminé que la non-reconnaissance des diplômes et des compétences acquises à l'étranger, la barrière linguistique due à la non-maîtrise de l'anglais, le manque d'expérience sur le marché du travail canadien, la faiblesse des réseaux sociaux et la discrimination sont les principaux obstacles rencontrés par les immigrants dans leur trajectoire d'insertion en emploi. Malgré ceux-ci, les immigrants ne se découragent pas et mettre en place diverses stratégies. Ainsi, le retour aux études postsecondaires, l'apprentissage de l'anglais, le recours aux réseaux sociaux, ne pas porter attention à la discrimination et prendre du recul face à ce phénomène sont certains des éléments qui ont favorisé l'insertion en emploi des participants de notre recherche.

Adenovirus Early region 1A(E1A) plays an important role in viral lytic infection and serves as a useful tool in the study of molecular mechanisms of gene regulation and gene expression. In addition to the ability of E1A functions to induce transactivation and transrepression of gene expression, E1A products play a critical role in transformation by adenovirus. A technique employing linker insertion mutagenesis scanning most of the E1A major regions was developed in this laboratory to systematically study the effect of E1A mutations on transcriptional transactivation and trans-repression functions as well as transforming ability (Bautista 1989). Results obtained showed that the unique region was the region primarily for transactivation in agreement with a wealth of other data and that transrepression was sensitive to insertions in CRII (conserved region II) and a region immediately following the unique region at the beginning of Exon II. However, transformation was not affected by repression-sensitive mutants. This thesis describes further studies carried out to create additional insertion mutants within conserved region of E1A to confirm and extend the results obtained by Bautista. A synthetic oligonucleotide of 39 base pair (13 aa) was introduced into two additional restriction sites in this region. As in previous work, the oligonucleotide could be inserted in either of two possible orientations. In one orientation, all three reading frames were open whereas all three reading frames of the other orientation contained stop codons which resulted in truncation of the E1A protein at the site of insertion. In addition, the insertion oligomer was designed with flanking BamHI sites to provide the opportunity of collapsing the full length insertion to a 6 base pair (2 aa) insertion. This allowed comparison to be made between mutations containing 13 aa insertions and those with 2 aa inserts at the same site to see how different oligopeptide segments would influence different functions. Trans-repression assays utilized a novel β-galactosidase assay developed by Bautista for characterizing CRII mutants expressing only the 12S product. The results suggested that CRII was an important region in terms of ability of E1A to transrepress. This negative regulatory function was sensitive to full length 13 aa insertions but not 2 aa inserts for those mutants made to date. Transforming ability of all CRII mutants was more or less impaired. Transactivation activity was not reduced by insertion at CRII except for mutants which were in the reverse orientation and had stop codons in their reading frame thus terminating the translation upstream of the unique region. In an effort to identify functional temperature sensitive mutants, DNA-mediated transformation assays of mutants within E1A functional regions were carried out at different temperatures. Two transformation temperature sensitive mutants were identified which failed to produce transformed colonies at 38.5°C but transformed efficiently at 32°C. No replication temperature sensitive mutants were identified among 61 mutant viruses. / Thesis / Master of Science (MS)

Dans cette recherche, il s'agit d'étudier la situation socioprofessionnelle de diplômés Bac + 5 de filières techniques à la recherche de première insertion à la sortie de l'université, principalement de connaître les stratégies qu'ils se donnent pour trouver le premier emploi à la sortie de l'université. Cette étude consistera à connaître les réelles difficultés d'insertion professionnelle de ces diplômés dans les six à douze mois qui suivent leur sortie de l'université et aussi de mettre en évidence les stratégies qu'ils se donnent pour trouver leur premier emploi. / In this research, it is to study the socio-occupations license graduates technical fields in search of the first insertion at the exit of the university, mainly know the strategies they give themselves to find the first job out of collège. This study is to know the real difficulties employability of graduates within six to twelve months after their leaving university and also to highlight the integration strategies they give themselves to find their first employment.