Arctic Focus: The Royal Canadian Navy in Arctic Waters, 1946-1949

Climate change is transforming the Arctic. Questions abound about what this will mean for the Canadian Forces, for Canada’s sover­eignty position, for northern peoples, and for stability and security in the circumpolar world. Fortunately, Canadians have encountered and debated similar issues in the past. This volume, featuring chapters by established and emerging scholars, offers essential historical analysis on Canadian Arctic security and sovereignty policies and practices since the Second World War. The “lessons learned” lay a solid foundation for future research and historiographical debate in this dynamic field, and should inform Canadian thinking on what is necessary to protect national interests in the twenty-first-century Arctic

In the Face of Overwhelming Evidence, Let’s Get Real

In 2007 the women of the Fitzroy Valley embarked on a courageous journey of societal recovery and restoration. They reversed the conversation on alcohol. The destructive impacts of drinking could no longer be confined to false arguments of the right to buy, or blaming individual irresponsibility. The women’s campaign to restrict the supply of alcohol was driven by a belief that this behaviour should not be normalised. They knew that the revitalisation of cultural practices and interconnected structures of family support and care was vital to empowering today’s community. In this Talking Heads seminar, June Oscar and Liz Elliott combine medical science, history and community justice into a narrative which challenges accepted societal norms. Their story presents the evidence and refreshing perspectives on how to empower people. Fitzroy Crossing is on a journey of creating a holistic, collaborative model of service delivery with wrap around health and educational supports for families and their children. As this model is constructed and positive changes made, June and Liz see in the lives of children and families today, a vibrant and healthy future

MscS-like Proteins Control Plastid Size and Shape in Arabidopsis thaliana

Background Mechanosensitive (MS) ion channels provide a mechanism for the perception of mechanical stimuli such as sound, touch, and osmotic pressure. The bacterial MS ion channel MscS opens in response to increased membrane tension and serves to protect against cellular lysis during osmotic downshock. MscS-like proteins are found widely in bacterial and archaeal species and have also been identified in fission yeast and plants. None of the eukaryotic members of the family have yet been characterized. Results Here, we characterize two MscS-like (MSL) proteins from Arabidopsis thaliana, MSL2 and MSL3. MSL3 can rescue the osmotic-shock sensitivity of a bacterial mutant lacking MS-ion-channel activity, suggesting that it functions as a mechanosensitive ion channel. Arabidopsis plants harboring insertional mutations in both MSL3 and MSL2 show abnormalities in the size and shape of plastids, which are plant-specific endosymbiotic organelles responsible for photosynthesis, gravity perception, and numerous metabolic reactions. MSL2-GFP and MSL3-GFP are localized to discrete foci on the plastid envelope and colocalize with the plastid division protein AtMinE. Conclusions Our data support a model wherein MSL2 and MSL3 control plastid size, shape, and perhaps division during normal plant development by altering ion flux in response to changes in membrane tension. We propose that MscS family members have evolved new roles in plants since the endosymbiotic event that gave rise to plastids

Evolution at shifting range margins

The speed at which biological range expansions occur has important consequences for species experiencing climate change, and for invasions by exotic organisms. There is growing empirical and theoretical evidence that during range expansions there is selection for increased dispersal, and that this can result in faster rates of spread. However, few models consider whether increased dispersal comes at a cost. In this thesis I investigated how two different trade-offs between dispersal and other traits affected the rates of range expansions. The first modelled a direct trade-off between dispersal and reproduction, and the second incorporated a trade-off so that adaptation to an environmental gradient came at a cost to dispersal. The first trade-off was investigated by modelling a population that consisted of two dispersal phenotypes, one that has a higher population growth rate and one that has a higher dispersal rate. Using a simple deterministic model it was found that when there was a big trade-off between the morphs in terms of these traits, anomalous invasion speeds were observed whereby a population consisting of both phenotypes invades at a speed faster than either single phenotype. It was found that these anomalous invasion speeds were robust to demographic stochasticty. Adding a shifting climate to the model revealed that a trade-off between dispersal and establishment ability can help a species to keep up with climate change. The second trade-off was investigated using a quantitative trait model, which revealed that a trade-off between dispersal and adaptation can result in the formation of range margins. Introducing a shifting environment allowed a species to expand its range at a speed determined by the steepness of the gradient and the size of the trade-off. These models reveal that trade-offs can alter range shifting dynamics, the consequences of which for predicting rates of range expansions were discussed

Hitting the High-Dimensional Notes: An ODE for SGD learning dynamics on GLMs and multi-index models

We analyze the dynamics of streaming stochastic gradient descent (SGD) in the high-dimensional limit when applied to generalized linear models and multi-index models (e.g. logistic regression, phase retrieval) with general data-covariance. In particular, we demonstrate a deterministic equivalent of SGD in the form of a system of ordinary differential equations that describes a wide class of statistics, such as the risk and other measures of sub-optimality. This equivalence holds with overwhelming probability when the model parameter count grows proportionally to the number of data. This framework allows us to obtain learning rate thresholds for stability of SGD as well as convergence guarantees. In addition to the deterministic equivalent, we introduce an SDE with a simplified diffusion coefficient (homogenized SGD) which allows us to analyze the dynamics of general statistics of SGD iterates. Finally, we illustrate this theory on some standard examples and show numerical simulations which give an excellent match to the theory.Comment: Preliminary versio

Training the Foot Soldiers of Inquiry: Development and Evaluation of a Graduate Teaching Assistant Learning Community

As part of a Howard Hughes Program for Innovation in Science Education grant at Iowa State University, a series of interdisciplinary graduate teaching assistant learning communities (TALC) were developed. The purpose of these communities was to create an environment to facilitate teaching assistants\u27 pedagogical development and training to enhance the implementation of inquiry experiences in the undergraduate laboratories. The TALC evaluated in this study were held for two consecutive semesters and included teaching assistants who facilitated multi-week course-based research experiences in their respective STEM courses. Topics discussed during the TALC were based on the teaching assistants\u27 concerns related to teaching this type of course. Evaluation consisted of weekly reflection responses, a pre- and post-survey of instructional methods they consider to facilitate inquiry, pre-post definitions of inquiry-based instruction, and end-of-semester evaluations of the learning community experiences. This article outlines the development of the TALC and findings from the various forms of evaluation. [ABSTRACT FROM AUTHOR

Two MscS Homologs Provide Mechanosensitive Channel Activities in the Arabidopsis Root

In bacterial and animal systems, mechanosensitive (MS) ion channels are thought to mediate the perception of pressure, touch, and sound 1, 2 and 3. Although plants respond to a wide variety of mechanical stimuli, and although many mechanosensitive channel activities have been characterized in plant membranes by the patch-clamp method, the molecular nature of mechanoperception in plant systems has remained elusive [4]. Likely candidates are relatives of MscS (Mechanosensitive channel of small conductance), a well-characterized MS channel that serves to protect E. coli from osmotic shock [5]. Ten MscS-Like (MSL) proteins are found in the genome of the model flowering plant Arabidopsis thaliana 4, 6 and 7. MSL2 and MSL3, along with MSC1, a MscS family member from green algae, are implicated in the control of organelle morphology 8 and 9. Here, we characterize MSL9 and MSL10, two MSL proteins found in the plasma membrane of root cells. We use a combined genetic and electrophysiological approach to show that MSL9 and MSL10, along with three other members of the MSL family, are required for MS channel activities detected in protoplasts derived from root cells. This is the first molecular identification and characterization of MS channels in plant membranes

To Podcast or not to Podcast? Pedagogical decision making in the use of new technologies

Podcasting is a cheap and portable technology that allows students to download and listen to lectures when and wherever convenient. Most students provided with Podcasts have embraced this technology and many view Podcasts as a useful additional learning resource. Hence, an increasing number of students are requesting lecture Podcasts from academic staff. This study investigated the pedagogical decision making of health science educators in the use of Podcasting technology. Data were gathered from interviews and via an online survey sent to all teaching staff within the Division of Health Sciences. Two thirds of the staff who responded (92/167; 55%) elected to Podcast their lectures. Most did so in response to staff or student expectations rather than pedagogically-based reasons. This study has shown that the decision making inherent in using Podcasting technology is based on student demand and anecdotal evidence rather than a sound pedagogical basis

Bayesian Hierarchical Modelling of Initial-Final Mass Relations Across Star Clusters

The initial-final mass relation (IFMR) of white dwarfs (WDs) plays an important role in stellar evolution. To derive precise estimates of IFMRs and explore how they may vary among star clusters, we propose a Bayesian hierarchical model that pools photometric data from multiple star clusters. After performing a simulation study to show the benefits of the Bayesian hierarchical model, we apply this model to five star clusters: the Hyades, M67, NGC 188, NGC 2168, and NGC 2477, leading to reasonable and consistent estimates of IFMRs for these clusters. We illustrate how a cluster-specific analysis of NGC 188 using its own photometric data can produce an unreasonable IFMR since its WDs have a narrow range of zero-age main sequence (ZAMS) masses. However, the Bayesian hierarchical model corrects the cluster-specific analysis by borrowing strength from other clusters, thus generating more reliable estimates of IFMR parameters. The data analysis presents the benefits of Bayesian hierarchical modelling over conventional cluster-specific methods, which motivates us to elaborate the powerful statistical techniques in this article