modCHIMERA: A novel murine closed-head model of moderate traumatic brain injury

AbstractTraumatic brain injury is a major source of global disability and mortality. Preclinical TBI models are a crucial component of therapeutic investigation. We report a tunable, monitored model of murine non-surgical, diffuse closed-head injury—modCHIMERA—characterized by impact as well as linear and rotational acceleration. modCHIMERA is based on the Closed-Head Impact Model of Engineered Rotational Acceleration (CHIMERA) platform. We tested this model at 2 energy levels: 1.7 and 2.1 Joules—substantially higher than previously reported for this system. Kinematic analysis demonstrated linear acceleration exceeding injury thresholds in humans, although outcome metrics tracked impact energy more closely than kinematic parameters. Acute severity metrics were consistent with a complicated-mild or moderate TBI, a clinical population characterized by high morbidity but potentially reversible pathology. Axonal injury was multifocal and bilateral, neuronal death was detected in the hippocampus, and microglial neuroinflammation was prominent. Acute functional analysis revealed prolonged post-injury unconsciousness, and decreased spontaneous behavior and stimulated neurological scores. Neurobehavioral deficits were demonstrated in spatial learning/memory and socialization at 1-month. The overall injury profile of modCHIMERA corresponds with the range responsible for a substantial portion of TBI-related disability in humans. modCHIMERA should provide a reliable platform for efficient analysis of TBI pathophysiology and testing of treatment modalities.</jats:p

Integrated knowledge translation strategies that enhance the lives of persons with dementia and their family caregivers

Purpose: To understand the lived experience of persons with dementia and their family caregivers who receive home care in northern Alberta, Canada, and to reveal how integrated knowledge translation (iKT) strategies influence the uptake of best available dementia care evidence over time. Sample: Three persons living with dementia and thirteen family caregivers were interviewed at the beginning of the study, nine months after implementation of the knowledge broker (KB), and six months after termination of the KB role (total interviews = 41). Method: The PARiHS framework guided our longitudinal case study that included two rural home care centres. A qualitative interpretive descriptive approach was used. A KB was hired for 12 months to facilitate the development of different iKT strategies with staff. Site A developed two strategies: 1) a planning meeting to discuss local needs and suggestions for improving access to dementia care information and community supports; and 2) the development of an information package. Site B focused on working through modules of the U-First program that entailed dementia education and training for the home care providers (HCPs). They then used the U-First wheels with clients during their home visits. Findings: Persons living with dementia spoke of both positive and negative aspects of their dementia journey and how they attempted to manage their lives. Family caregivers struggled to find the best approaches and supports to use to enable their family member with dementia to remain at home for as long as possible. iKT strategies such as a KB, the information resource package developed by the HCPs, use of the U-First modules and wheels, and a support group were examples of effective iKT. Conclusion: iKT strategies and projects increased access to dementia care information and supports. These assisted caregivers to better care for their family member for longer periods at home. Keywords: Persons living with dementia, family caregivers, integrated knowledge translation strategies, rural, and home car

Bounding biomass in the Fisher equation

The FKPP equation with a variable growth rate and advection by an incompressible velocity field is considered as a model for plankton dispersed by ocean currents. If the average growth rate is negative then the model has a survival-extinction transition; the location of this transition in the parameter space is constrained using variational arguments and delimited by simulations. The statistical steady state reached when the system is in the survival region of parameter space is characterized by integral constraints and upper and lower bounds on the biomass and productivity that follow from variational arguments and direct inequalities. In the limit of zero-decorrelation time the velocity field is shown to act as Fickian diffusion with an eddy diffusivity much larger than the molecular diffusivity and this allows a one-dimensional model to predict the biomass, productivity and extinction transitions. All results are illustrated with a simple growth and stirring model.Comment: 32 Pages, 13 Figure

Evidence of strong small-scale population structure in the Antarctic freshwater copepod Boeckella poppei in lakes on Signy Island, South Orkney Islands

Environmental conditions were particularly severe during the Last Glacial Maximum, altering the distribution of the Southern Hemisphere biota, particularly at higher latitudes. The copepod Boeckella poppei is the only macroscopic continental invertebrate species known to be distributed today across the three main biogeographic regions in Antarctica as well as in southern South America. Signy Island (South Orkney Islands) is a unique location for the study of Antarctic freshwater ecosystems due to its location and geographic isolation; it contains 17 lakes in several low altitude catchments. We conducted phylogeographic and demographic analyses using the cox1 gene on 84 individuals of B. poppei from seven lakes across Signy Island. We recorded low levels of genetic diversity and a strong genetic differentiation signal between the eastern and western valleys within the island. Phylogeographic structure and demographic inference analyses suggested at least one asymmetrical dispersal event from west to east. Demographic inference detected a strong signal of population growth during the deglaciation process, which may have followed either (1) a strong genetic bottleneck due to a reduction in population size during the last glacial period, or (2) a founder effect associated with postglacial recolonization of Signy Island from elsewhere. The genetic architecture of this island's populations of B. poppei shows that historical events, rather than continuous dispersal events, likely played a major role in the species' current distribution. Finally, our study considers possible mechanisms for dispersal and colonization success of the most dominant species in the Antarctic freshwater community

Size-Dependent Transition to High-Dimensional Chaotic Dynamics in a Two-Dimensional Excitable Medium

The spatiotemporal dynamics of an excitable medium with multiple spiral defects is shown to vary smoothly with system size from short-lived transients for small systems to extensive chaos for large systems. A comparison of the Lyapunov dimension density with the average spiral defect density suggests an average dimension per spiral defect varying between three and seven. We discuss some implications of these results for experimental studies of excitable media.Comment: 5 pages, Latex, 4 figure

Queering Development? The Unsettling Geographies of South–South Cooperation

This paper deploys queer theory as a way of approaching South–South Cooperation (SSC). It examines the ways in which Southern development partners are not simply up-ending the long-standing spatialities, imaginaries and identities (re)produced through the mainstream international development regime, but queering terminologies and definitions, while presenting themselves in fluid ways, enrolling different identities and attributes in different places and to different audiences. At the same time, a queer lens reveals the (re)inscription of gendered, sexualised and racialised identities and hierarchies through the relationships, intimacies and practices of SSC. The paper proposes that queer theory can offer productive insights into the complex and compelling phenomenon of SSC, and the transgressive challenges to the postcolonial hierarchies and binaries of “traditional” international development

The Wicked Machinery of Government: Malta and the Problems of Continuity under the New Model Administration

This is a study focused on the early years of British rule in Malta (1800-1813). It explores the application to the island of the “new model” of colonial government, one based on direct rule from London mediated by the continuation of existing laws and institutions. Systemic deficiencies are identified. These tended to undermine the effectiveness of direct British rule. This study also reveals, in the context of legal and constitutional continuity, unresolved tensions between modernity and tradition. The political stability of the island was damaged and the possibility of continued British possession was threatened