Presentations for some monoids of injective partial transformations on a finite chain.

Communications in Algebra, 33 (2005), p. 587-604

Automorphisms of partial endomorphism semigroups

Publicationes Mathematicae Debrecen

Geodupa - a geography-driven partial membership algorithm

Trabalho apresentado no âmbito do Mestrado em Engenharia Informática, como requisito parcial para obtenção do grau de Mestre em Engenharia Informática

Partial Least Square – Path Modeling: metodologia, software e aplicação

Trabalho de Projeto apresentado como requisito parcial para obtenção do grau de Mestre em Estatística e Gestão de Informação

Partial replication in distributed software transactional memory

Dissertação para obtenção do Grau de Mestre em Engenharia Informática

Cohesion decay: quantitative analysis of partial sister chromatid cohesion

Cell division is a highly dynamic process where sister chromatids remain associated with each other from the moment of DNA replication until the later stages of mitosis, giving rise to two daughter cells with equal genomes. The “molecular glue” that links sister DNA molecules is called cohesin, a tripartite ring-like protein complex composed of two Structural Maintenance of Chromosome proteins (Smc1 and Smc3) bridged by a kleisin subunit Rad21/Scc1, that together prevent precocious sister chromatid separation. Accumulating evidence has suggested that cohesion decay may be the cause of segregation errors that underlie certain human pathologies. However it remains to be determined how much cohesin loss abolishes functional sister chromatid cohesion. To answer these questions, we have developed different experimental conditions aiming to titrate the levels of cohesin on mitotic chromosomes in a precise manner. Using these tools, we will determine the minimal amount of cohesin needed to confer functional cohesion. The approaches described here take advantage of a system in Drosophila melanogaster where the Tobacco Etch Virus (TEV) protease can cleave the Rad21 subunit of cohesin leading to precocious sister chromatid separation. Firstly, we tried to express different levels of TEV protease to obtain partial loss of cohesion. However, this approach has failed to produce systematic different levels of sister chromatid separation. Most of the work was therefore focused on a second strategy, for which we established strains with different levels of cohesin sensitive/cohesin resistant to TEV protease. Strains containing different amounts of functional cohesin (TEV resistant) were tested by in vitro cleavage and by in vivo injections in embryos for their ability to promote sister chromatid cohesion. Our results reveal that removal of half of the cohesin complexes does not impair chromosome segregation, implying that chromosome cohesion is less sensitive to cohesin amounts than previously anticipated.

Specification of a partial replication protocol with TLA+

Nowadays, data available and used by companies is growing very fast creating the need to use and manage this data in the most efficient way. To this end, data is replicated overmultiple datacenters and use different replication protocols, according to their needs, like more availability or stronger consistency level. The costs associated with full data replication can be very high, and most of the times, full replication is not needed since information can be logically partitioned. Another problem, is that by using datacenters to store and process information clients become heavily dependent on them. We propose a partial replication protocol called ParTree, which replicates data to clients, and organizes clients in a hierarchy, using communication between them to propagate information. This solution addresses some of these problems, namely by supporting partial data replication and offline execution mode. Given the complexity of the protocol, the use of formal verification is crucial to ensure the protocol two correctness properties: causal consistency and preservation of data. The use of TLA+ language and tools to formally specificity and verify the proposed protocol are also described.