The threshold for integer homology in random d-complexes

Let Y ~ Y_d(n,p) denote the Bernoulli random d-dimensional simplicial complex. We answer a question of Linial and Meshulam from 2003, showing that the threshold for vanishing of homology H_{d-1}(Y; Z) is less than 80d log n / n. This bound is tight, up to a constant factor.Comment: 12 pages, updated to include an additional torsion group boun

A Parameterization Study of Short Read Assembly Using the Velvet Assembler

In this study, we examine approaches to the problem of assembling large, contiguous sections of genetic code from short reads generated from laboratory techniques. We explore the Eulerian Path approach in detail, utilizing a de Bruijn Graph, and demonstrate current software technologies and algorithms using a sample genome. We investigate the input parameters of Velvet and discuss choice implications in the context of the E. coli putA/b1014 gene

Canada's Greek Moment: Transnational Politics, Activists, and Spies During the Long Sixties

This dissertation examines Greek immigrant homeland politics during the period of Greeces military dictatorship, 1967 to 1974, in Toronto and Montreal. It carefully considers the internal dynamics of anti-junta activism in Canadas Greek populations, but it also contemplates the meanings of external perceptions, particularly from the Canadian state and Canadian public discourse. The study acknowledges the dominant paradigm of Greek immigrants as unskilled workers, however, it demonstrates that this archetype is not monolithic. In many ways, it is challenged by a small number of Greeks who possessed skills to write letters to politicians, create petitions, organize public rallies, and politically mobilize others. At the same time, this dissertation carefully considers Canadas social and political environment and shows how uniquely Canadian politics ran parallel to and informed Greek homeland politics. Transnationalism is used as an analytical tool, which challenges the meaning of local/national borders and the perception that they are sealed containers. The main argument expressed here is that environments shape movements and migrant political culture does not develop in a vacuum. Each chapter deals with specific nuances of anti-junta activism in Toronto and Montreal. Chapter One examines the organized voices of the Greek communitys anti-dictatorship movement. The chapters latter section looks at how the Panhellenic Liberation Movement (PAK), led by Andreas Papandreou, consolidated itself as the main mouthpiece against Greeces authoritarian regime. Chapter Two demonstrates that social movements occurring in Canada meshed neatly with anti-junta sentiment, mobilizing many Canadians against the dictatorship. Chapter Three shows how a few skilled Greeks shaped transnational narratives of resistance in local Greek leftist press. Chapters Four and Five examine RCMP surveillance documents related to local politics in Toronto and Montreal. In doing so, the chapters reveal that regional circumstances, particularly Quebecs Quiet Revolution, shaped security concerns and definitions of Greek subversive activities. Overall, Canadas Greek moment was a complex tale of activism, surveillance, and transnational politics

Asymmetric Fluid Criticality

This work investigates features of critical phenomena in fluids. The canonical description of critical phenomena, inspired by the Ising model, fails to capture all features observed in fluid systems, specifically those associated with the density or compositional asymmetry of phase coexistence. A new theory of fluid criticality, known as "complete scaling", was recently introduced. Given its success in describing experimental results, complete scaling appears to supersede the previous theory of fluid criticality that was consistent with a renormalization group (RG) analysis of an asymmetric Landau-Ginzburg-Wilson (LGW) Hamiltonian. In this work, the complete scaling approach and the equation of state resulting from the RG analysis are shown to be consistent to order ε, where ε = 4 - d with d being the spatial dimensionality. This is accomplished by developing a complete scaling equation of state, and then defining a mapping between the complete scaling mixing-parameters and the coefficients of the asymmetric LGW Hamiltonian, thereby generalizing previous work [Phys. Rev. Lett. 97, 025703 (2006)] on mean-field equations of state. The seemingly different predictions of these approaches are shown to stem from an intrinsic ambiguity in the interpretation of the ε-expansion at fixed order. To first order in ε it is found that the asymmetric correction-to-scaling exponent θ5 predicted by the RG calculations can be fully absorbed into the 2β exponent of complete scaling. Complete scaling is then extended to spatially inhomogeneous fluids in the approximation η=0, where η is the anomalous dimension. This extension enables one to obtain a fluctuation-modified asymmetric interfacial density profile, which incorporates effects from both the asymmetry of fluid phase coexistence and the associated asymmetry of the correlation length. The derived asymmetric interfacial profile is used to calculate Tolman's length, the coefficient of the first curvature correction to the surface tension. The previously predicted divergence of Tolman's length at the critical point is confirmed and the amplitude of this divergence is found to depend nonuniversally on the asymmetry of the correlation length

Black education in Canada West: A parochial solution to a secular problem. Rev. M. M. Dillon and the Colonial Church and School Society

African-Americans fled the United States of America during the nineteenth century to escape slavery. The majority of the emigrants took refuge in Upper Canada. Slavery had been abolished by 1834 in all British colonial possessions. Blacks were promised protection from racism by virtue of British institutions. Upper Canada offered the fugitives a chance to begin a new life. Life in Canada West was not to be as joyful as was promised. When Blacks arrived in the British colony they were treated as outsiders, outcast from society. The prejudices of the day flourished throughout the countryside. Racism was manifested in the refusal of local administrators to allow African-American children to attend government financed schools. The settlers were not prepared to abandon their long held fear of Blacks and they prevented the integration of children of all races. The administration did not offer support and protection from intolerance. The education system failed Black children by not allowing them to attend classes even though their parents paid their school taxes. The British establishment recognized the injustice and tried to remedy the situation by opening schools of their own. The Colonial Church and School Society opened a school in London, Canada West. The Anglican missionaries wanted to prove that Blacks could be educated and become part of society. The aims of the founder of the school, Rev. M.M. Dillon, differed from the aims of the CCSS. He wanted to have Blacks and whites educated together to their mutual benefit. His participation in the founding and running of the Mission is central to the operation of the Mission to the Fugitive Slaves of Canada West. He did not maintain the support of the influential members of the London society and was removed from his post. The point of contention was that he had allowed more whites in the school than Black children. He left the Mission in 1856 and the Mission closed in 1858

Reward context determines risky choice in pigeons and humans

Whereas humans are risk averse for monetary gains, other animals can be risk seeking for food rewards, especially when faced with variable delays or under significant deprivation. A key difference between these findings is that humans are often explicitly told about the risky options, whereas non-human animals must learn about them from their own experience. We tested pigeons (Columba livia) and humans in formally identical choice tasks where all outcomes were learned from experience. Both species were more risk seeking for larger rewards than for smaller ones. The data suggest that the largest and smallest rewards experienced are overweighted in risky choice. This observed bias towards extreme outcomes represents a key step towards a consilience of these two disparate literatures, identifying common features that drive risky choice across phyla

On the number of unlabeled vertices in edge-friendly labelings of graphs

Let $G$ be a graph with vertex set $V(G)$ and edge set $E(G)$, and $f$ be a 0-1 labeling of $E(G)$ so that the absolute difference in the number of edges labeled 1 and 0 is no more than one. Call such a labeling $f$ \emph{edge-friendly}. We say an edge-friendly labeling induces a \emph{partial vertex labeling} if vertices which are incident to more edges labeled 1 than 0, are labeled 1, and vertices which are incident to more edges labeled 0 than 1, are labeled 0. Vertices that are incident to an equal number of edges of both labels we call \emph{unlabeled}. Call a procedure on a labeled graph a \emph{label switching algorithm} if it consists of pairwise switches of labels. Given an edge-friendly labeling of $K_n$, we show a label switching algorithm producing an edge-friendly relabeling of $K_n$ such that all the vertices are labeled. We call such a labeling \textit{opinionated}.Comment: 7 pages, accepted to Discrete Mathematics, special issue dedicated to Combinatorics 201