Unobstructed Lagrangian cobordism groups of surfaces

We study Lagrangian cobordism groups of closed symplectic surfaces of genus $g \geq 2$ whose relations are given by unobstructed, immersed Lagrangian cobordisms. Building upon work of Abouzaid and Perrier, we compute these cobordism groups and show that they are isomorphic to the Grothendieck group of the derived Fukaya category of the surface.Comment: 60 pages, 15 figure

Rigidité du crochet de Poisson en topologie symplectique

Ce mémoire est une introduction aux phénomènes de rigidité C0 en topologie symplectique. Plus précisément, il sera question de la rigidité C0 du crochet de Poisson sur une variété symplectique. Les notions élémentaires de la géométrie symplectique et de la dynamique hamiltonienne sont rappelées au premier chapitre. Le second chapitre traite de la géométrie d’Hofer du groupe des difféomorphismes hamiltoniens d’une variété symplectique. Le chapitre 3 concerne l’application de la géométrie d’Hofer à l’étude de fonctionnelles définies à partir du crochet de Poisson. Le résultat principal qui est démontré, dû à Buhovski, Entov et Polterovich, est la semi-continuité inférieure dans la topologie C0 de la fonctionnelle qui associe à chaque paire de fonctions la norme uniforme de leur crochet de Poisson.This master’s thesis is an introduction to C0 rigidity phenomena in symplectic topology. More precisely, the main concern is the C0 rigidity of the Poisson bracket on a symplectic manifold. The elementary notions of symplectic geometry and Hamiltonian dynamics are recalled in the first chapter. The second chapter introduces the Hofer geometry of the group of Hamiltonian diffeomorphisms of a symplectic manifold. Chapter 3 concerns the application of Hofer geometry to the study of functionals defined in terms of the Poisson bracket. The main result, due to Buhovski, Entov and Polterovich, is the lower semi-continuity of the functional which assigns to every pair of functions the uniform norm of their Poisson bracket

Range expansion and the origin of USA300 north american epidemic methicillin-resistant Staphylococcus aureus

The USA300 North American epidemic (USA300-NAE) clone of methicillin-resistant Staphylococcus aureus has caused a wave of severe skin and soft tissue infections in the United States since it emerged in the early 2000s, but its geographic origin is obscure. Here we use the population genomic signatures expected from the serial founder effects of a geographic range expansion to infer the origin of USA300-NAE and identify polymorphisms associated with its spread. Genome sequences from 357 isolates from 22 U.S. states and territories and seven other countries are compared. We observe two significant signatures of range expansion, including decreases in genetic diversity and increases in derived allele frequency with geographic distance from the Pennsylvania region. These signatures account for approximately half of the core nucleotide variation of this clone, occur genome wide, and are robust to heterogeneity in temporal sampling of isolates, human population density, and recombination detection methods. The potential for positive selection of a gyrA fluoroquinolone resistance allele and several intergenic regions, along with a 2.4 times higher recombination rate in a resistant subclade, is noted. These results are the first to show a pattern of genetic variation that is consistent with a range expansion of an epidemic bacterial clone, and they highlight a rarely considered but potentially common mechanism by which genetic drift may profoundly influence bacterial genetic variation. IMPORTANCE The process of geographic spread of an origin population by a series of smaller populations can result in distinctive patterns of genetic variation. We detect these patterns for the first time with an epidemic bacterial clone and use them to uncover the clone’s geographic origin and variants associated with its spread. We study the USA300 clone of methicillin-resistant Staphylococcus aureus, which was first noticed in the early 2000s and subsequently became the leading cause of skin and soft tissue infections in the United States. The eastern United States is the most likely origin of epidemic USA300. Relatively few variants, which include an antibiotic resistance mutation, have persisted during this clone’s spread. Our study suggests that an early chapter in the genetic history of this epidemic bacterial clone was greatly influenced by random subsampling of isolates during the clone’s geographic spread

Was John Gill a hyper-Calvinist? Determining Gill's theological identity

Historians have long debated John Gill's theological identity. Some contend he was a hyper-Calvinist who denied the free offer of the Gospel and the duty of all people to receive it. Others seek to defend him from this charge. Defences of Gill have surprisingly failed to assess his convictions on these matters in the context of his overall soteriological project. Gill constructed a soteriology that minimized human responsibility in the reception of salvation, and this framework indeed led him to espouse a practical theology marked by the rejection of Gospel offers and duty faith, two tenets commonly associated with hyper-Calvinism. Reading Gill in light of his soteriology therefore helps to settle this important question of his theological identity

Was John Gill a hyper-Calvinist? Determining Gill's theological identity

Historians have long debated John Gill's theological identity. Some contend he was a hyper-Calvinist who denied the free offer of the Gospel and the duty of all people to receive it. Others seek to defend him from this charge. Defences of Gill have surprisingly failed to assess his convictions on these matters in the context of his overall soteriological project. Gill constructed a soteriology that minimized human responsibility in the reception of salvation, and this framework indeed led him to espouse a practical theology marked by the rejection of Gospel offers and duty faith, two tenets commonly associated with hyper-Calvinism. Reading Gill in light of his soteriology therefore helps to settle this important question of his theological identity

John Gill and the history of redemption as mere shadow:exploring Gill's doctrine of the covenant of redemption

John Gill was an influential minister and theologian of the eighteenth century. Deeply influenced by the Reformed tradition, he made significant innovation to the doctrine of the covenant of redemption. Current surveys of his theology have unfortunately not adequately explored this innovation. The primary cause of this failure is a lack of attention to Gill’s historical context, a context shaped by doctrinal antinomianism and no-offer Calvinism. This article will contextualize Gill’s thought and provide a more accurate reading of his covenant theology by arguing that he offered a unique construction of the covenant of redemption that radically minimized human agency in the reception of salvation