Probabilistic lower bounds on maximal determinants of binary matrices

Let ${\mathcal D}(n)$ be the maximal determinant for $n \times n$ $\{\pm 1\}$-matrices, and $\mathcal R(n) = {\mathcal D}(n)/n^{n/2}$ be the ratio of ${\mathcal D}(n)$ to the Hadamard upper bound. Using the probabilistic method, we prove new lower bounds on ${\mathcal D}(n)$ and $\mathcal R(n)$ in terms of $d = n-h$, where $h$ is the order of a Hadamard matrix and $h$ is maximal subject to $h \le n$. For example, $\mathcal R(n) > (\pi e/2)^{-d/2}$ if $1 \le d \le 3$, and $\mathcal R(n) > (\pi e/2)^{-d/2}(1 - d^2(\pi/(2h))^{1/2})$ if $d > 3$. By a recent result of Livinskyi, $d^2/h^{1/2} \to 0$ as $n \to \infty$, so the second bound is close to $(\pi e/2)^{-d/2}$ for large $n$. Previous lower bounds tended to zero as $n \to \infty$ with $d$ fixed, except in the cases $d \in \{0,1\}$. For $d \ge 2$, our bounds are better for all sufficiently large $n$. If the Hadamard conjecture is true, then $d \le 3$, so the first bound above shows that $\mathcal R(n)$ is bounded below by a positive constant $(\pi e/2)^{-3/2} > 0.1133$.Comment: 17 pages, 2 tables, 24 references. Shorter version of arXiv:1402.6817v4. Typos corrected in v2 and v3, new Lemma 7 in v4, updated references in v5, added Remark 2.8 and a reference in v6, updated references in v

A Pragmatist Reading of Mary Parker Follett’s Integrative Process

For most of the 20th century Mary Parker Follett (1868–1933) was one of the “invisible women” in the history of American philosophy, although her work was taken seriously by philosophers of her time. While some have described Follett as an idealist, this essay develops the pragmatist and feminist elements of Follett’s philosophy. In particular, Follett’s concept of “integration” can be clarified by reading it through a pragmatist lens, connecting it with Dewey’s writing on experience, and with Jamesian pluralism. Follett also shares with Jane Addams an understanding of the creative integrative power of diversity; Addams directly referenced Follett in 1930 when she describes how conflicts were resolved in the process of mutual action. The latter part of this essay discusses the contemporary relevance of Follett’s integrative “power-with” methodology in feminist thought. Taking integrative work seriously requires preparation and training, and Follett’s writing on education for integration has implications for contemporary pedagogical practice

PaPaS: A Portable, Lightweight, and Generic Framework for Parallel Parameter Studies

The current landscape of scientific research is widely based on modeling and simulation, typically with complexity in the simulation's flow of execution and parameterization properties. Execution flows are not necessarily straightforward since they may need multiple processing tasks and iterations. Furthermore, parameter and performance studies are common approaches used to characterize a simulation, often requiring traversal of a large parameter space. High-performance computers offer practical resources at the expense of users handling the setup, submission, and management of jobs. This work presents the design of PaPaS, a portable, lightweight, and generic workflow framework for conducting parallel parameter and performance studies. Workflows are defined using parameter files based on keyword-value pairs syntax, thus removing from the user the overhead of creating complex scripts to manage the workflow. A parameter set consists of any combination of environment variables, files, partial file contents, and command line arguments. PaPaS is being developed in Python 3 with support for distributed parallelization using SSH, batch systems, and C++ MPI. The PaPaS framework will run as user processes, and can be used in single/multi-node and multi-tenant computing systems. An example simulation using the BehaviorSpace tool from NetLogo and a matrix multiply using OpenMP are presented as parameter and performance studies, respectively. The results demonstrate that the PaPaS framework offers a simple method for defining and managing parameter studies, while increasing resource utilization.Comment: 8 pages, 6 figures, PEARC '18: Practice and Experience in Advanced Research Computing, July 22--26, 2018, Pittsburgh, PA, US

A STUDY OF FLIGHT SIMULATION TRAINING TIME, AIRCRAFT TRAINING TIME, AND PILOT COMPETENCE AS MEASURED BY THE NAVAL STANDARD SCORE

The purpose of the study was to investigate the relationships between US Navy T-45C flight simulation training time, actual aircraft training time, and intermediate and advanced jet pilot competence as measured by the Naval Standard Score (NSS). Examining the relationships between US Navy T-45C flight simulation time and actual aircraft flight time may provide further information on flight simulation training versus actual aircraft training to aviation authorities, flight instructors, the military aviation community, the commercial aviation community, and academia. The study was non-experimental, correlational, causal-comparative with an emphasis upon the establishment of mathematic and predictive relationships using archival data from the Chief of Naval Air Training (CNATRA) Training Information System (TIMS) database. CNATRA aircraft hours, flight simulation hours, and NSS scores of intermediate and advanced flight students from 2015 to 2017 were analyzed and compared. Actual aircraft time was found to be a significant predictor of NSS scores for both intermediate and advanced pilot trainees. Implications of the study include recommendations for future research and strategies to improve flight simulation in pilot training

Transformative Possibilities: Liberal Education at Grand Valley State University

The readings in the book Reflect, Connect, Engage (2013) offer both an invitation and a challenge as they open the reader to possibilities of transformation. By engaging these voices you are welcomed into a community of learners that includes all of us at Grand Valley, students, faculty and staff, all of us learning from each other as well as from work of great thinkers and activists. GVSU is founded on the practice of liberal education -- an education that holds the possibility of permanently enriching our lives, assisting in the development of the capacities and skills necessary for our vocations, and preparing us for thoughtful participation in our democracy. Like justice, democracy, or freedom, liberal education is one of those concepts that calls us to higher thinking and cannot be defined easily. Yet it must be understood and claimed individually if we are to get the full value from the experience

Speciation and hybridization in Jamaican-endemic Streamertail Hummingbirds (Trochilus polytmus and T. scitulus)

Streamertails hummingbirds (Trochilus polytmus and T. scitulus) are recently diverged sister taxa that appear to have speciated in situ on the island of Jamaica. They are distinguished by male bill color, a secondary sexual trait that is coral red in T. polytmus and jet black in T. scitulus. They hybridize in a narrow zone where their ranges meet in eastern Jamaica. In Chapter 2, I performed a formal population survey of T. scitulus to determine the size of the population, which was unknown. I determined that the total population contains well over 100,000 individuals despite its limited geographic range. In Chapter 3, I build on previous studies to identify divergent morphological and genetic traits. Additionally, I use geographic cline models to determine the center and widths of individual clines and make inferences about the relative strength of selection acting on each trait. The clines for male bill color (2.2 km) and bill width (13.9 km) were narrow relative to neutral expectations and centered on the Rio Grande Valley. Female values were slightly wider. Consistent with expectations for recently diverged species, I detected little to no neutral genomic differentiation using six microsatellites, but a Radseq dataset containing 6,451 single nucleotide polymorphisms (SNPs) generated by a genotyping-by-sequencing protocol showed modest genetic differentiation between species. A narrow subset of SNPs (n = 23) with high loadings in a discriminant function analysis may be physically or epistatically linked to the divergent morphological traits. A structure analysis based on these discriminant SNPs shows a range of admixture assignments in the hybrid zones and strong differences in assignment between the parental species. A geographic cline analysis based on admixture assignments revealed a narrow cline (6.6 km) also centered on the Rio Grande. Finally, I performed a transcriptomics study to examine baseline differences in gene expression. While gene expression profiles were extremely similar, four genes showed significant gene expression differences. One gene, BLOC-1S1, is a ubiquitously expressed gene that is associated with pigmentation disorders in mice and humans. Its role in avian pigmentation is not well characterized, but is one gene that warrants further investigation as a candidate gene underpinning male bill color. I also looked at sequence divergence across the assembled transcripts. This panel of SNPs showed low divergence and little evidence for positive selection, indicating that divergent genes may be few and potentially located in regulatory regions not captured here