arXiv subjects

Stephen Allen

Publications and source records attributed to Stephen Allen.

5 recordsLinked to original sources

arXiv2024

The Human Genomic Landscape of Oceania

Oceania and Island Southeast Asia have a rich, yet understudied, human genomic landscape. This region encompasses some of the first areas inhabited by humans following the out-of-Africa expansion, includes populations with the highest levels of archaic hominin introgression, and contains Pacific islands that are among the most remote continuously inhabited locations in the world. Here, we describe the first region-wide analysis of individuals from population groups spanning Oceania and its broad perimeter. In total we generate and analyze genome-wide data from 92 different populations, 58 separate islands, and 30 countries, covering one third of the planet. Leveraging this diverse dataset, we resolve genetic connections among islands, providing a detailed view of regional population structure and identifying the island groups involved in the settlement of several Polynesian Outliers. Ancestry-specific analyses allow us to deconvolve different layers of history, from tracing groups deriving their Austronesian ancestry via the Lapita expansion to quantifying variable archaic introgression across the basal Papuan component of Oceanians and Southeast Asians. Finally, we map biomedically relevant variants across Oceania and Southeast Asia, observing pronounced allele-frequency differences between population groups. Together, these findings refine models of oceanic settlement and admixture and establish a comprehensive reference that will advance global efforts to ensure broad and equitable representation in human genomics.

q-bio.PE↗

arXiv2014

Spatial Modelling Techniques in Microsoft Excel

We begin by considering the expectations of the creators of VisiCalc, the first spreadsheet. The emphasis is on the nature of the spreadsheet grid. The grid is taken as a presentational method for showing a solution to a Sudoku puzzle. We consider methods or approaches for the solution. We look at the relationship between this model and academic papers on the methods for describing and categorising end-user models generally. We consider whether the type of model described here should be categorised separately. The complexity of the model is reviewed in the context of commendations to minimise overly sophisticated presentational constructs and formulae.

cs.HC↗

arXiv2012

On the Interpretation of Spreadsheets within their Environment

A demonstration in MS Excel to show how users can connect their spreadsheet models to the external environment that the model represents. We employ indexes to generate a list of relevant evidence that is hyperlinked to the context in which the evidence is discussed. The hyperlinks between the index and the contextual discussion have their own specific presentational identity. We contend that these presentational differences aid the integrity and understanding of complex models. Where models are complex, separate individual results can lead to contradictory conclusions. The demonstration includes a methodology for interpreting the analyses within a workbook and presenting them in the form of a standard written report.

cs.SE↗

arXiv2005

Gauge Invariant Uniqueness Theorem for Corners of k-graphs

For a finitely aligned k-graph $Λ$ with X a set of vertices in $Λ$ we define a universal C*-algebra called $C^*(Λ,X)$ generated by partial isometries. We show that $C^*(Λ,X)$ is isomorphic to the corner $P_XC^*(Λ)P_X$, where $P_X$ is the sum of vertex projections in X. We then prove a version of the Gauge Invariant Uniqueness Theorem for $C^*(Λ,X)$, and then use the theorem to prove various results involving fullness, simplicity and Morita equivalence as well as new results involving symbolic dynamics.

math.OA↗

arXiv2004

A dual graph construction for higher-rank graphs, and $K$-theory for finite 2-graphs

Given a $k$-graph $Λ$ and an element $p$ of $\NN^k$, we define the dual $k$-graph, $pΛ$. We show that when $Λ$ is row-finite and has no sources, the $C^*$-algebras $C^*(Λ)$ and $C^*(pΛ)$ coincide. We use this isomorphism to apply Robertson and Steger's results to calculate the $K$-theory of $C^*(Λ)$ when $Λ$ is finite and strongly connected and satisfies the aperiodicity condition.

math.OA↗