339 research outputs found

    SAS Macro BDM for Fitting the Dale Regression Model to Bivariate Ordinal Response Data

    Get PDF
    A SAS macro for fitting an extension of the Dale (1986) regression model to bivariate ordinal data is provided. The macro is described in detail and examples from Dale (1986) and McMillan, Hanson, Bedrick, and Lapham (2005) are discussed.

    “Learning Service” in International Contexts: Partnership-based Service-Learning and Research in Cape Town, South Africa

    Get PDF
    In this paper we explore an approach to developing and implementing service-learning and community-based research in a study-abroad program in Cape Town, South Africa. Drawing on a notion of partnerships reflecting the values of accompaniment and transparency, and influenced by the importance of learning service, we outline an intentional, engaged pedagogy and program design emphasizing collaborative inquiry and partnership development. However, such an approach is challenging and demands that we include an ontological project as part of our work. This, we believe, is crucial if global service-learning (GSL), often taking place in the Global South, is to become a robust, critical, and ethical practice

    In situ estimation of subsurface hydro-geomechanical properties using the groundwater response to semi-diurnal Earth and atmospheric tides

    Get PDF
    Subsurface hydro-geomechanical properties crucially underpin the management of Earth\u27s resources, yet they are predominantly measured on core samples in the laboratory while little is known about the representativeness of in situ conditions. The impact of Earth and atmospheric tides on borehole water levels is ubiquitous and can be used to characterise the subsurface. We illustrate that disentangling the groundwater response to Earth (M₂) and atmospheric tidal (S₂) forces in conjunction with established hydraulic and linear poroelastic theories leads to a complete determination of the whole hydro-geomechanical parameter space for unconsolidated systems. Further, the characterisation of consolidated systems is possible when using literature estimates of the grain compressibility. While previous field investigations have assumed a Poisson\u27s ratio from literature values, our new approach allows for its estimation under in situ field conditions. We apply this method to water level and barometric pressure records from four field sites with contrasting hydrogeology. Estimated hydro-geomechanical properties (e.g. specific storage; hydraulic conductivity; porosity; shear, Young\u27s, and bulk moduli; Skempton\u27s and Biot–Willis coefficients; and undrained or drained Poisson\u27s ratios) are comparable to values reported in the literature, except for consistently negative drained Poisson\u27s ratios, which is surprising. Our results reveal an anisotropic response to strain, which is expected for heterogeneous (layered) lithological profiles. Closer analysis reveals that negative Poisson\u27s ratios can be explained by in situ conditions differing to those from typical laboratory core tests and the small strains generated by Earth and atmospheric tides. Our new approach can be used to passively, and therefore cost-effectively, estimate subsurface hydro-geomechanical properties representative of in situ conditions and it improves our understanding of the relationship between geological heterogeneity and geomechanical behaviour

    Africa 2060: good news from Africa, April 16, 2010

    Full text link
    This repository item contains a single issue of the Pardee Conference Series, As the keystone event of a research program called “Africa 2060,” the Frederick S. Pardee Center for the Study of the Longer-Range Future at Boston University convened a conference on April 16, 2010 called Africa 2060: Good News from Africa. The program featured more than a dozen expert panelists from Boston University and across the world, and the approximately 100 participants included many African scholars and citizens from the continent who contributed to lively and well-informed discussion. The Pardee Center conference was co-sponsored by Boston University’s Africa Studies Center (ASC), the African Presidential Archives & Research Center (APARC), and the Global Health & Development Center (GHDC).This report provides commentary reflecting upon and information pertaining to the substance of the conference. An introductory overview looks at the major issues discussed at the event, which are placed within the larger literature on Africa’s future. Four short essays prepared by Boston University graduate students provide readers with more specific reflections and highlights of each conference session and the main issues discussed by panelists. The final section presents analyses of key trends and projections related to societal, economic, and governance issues for Africa and a commentary on what this information tells us about the drivers that will determine the continent’s future

    Pathological phosphorylation of tau and TDP-43 by TTBK1 and TTBK2 drives neurodegeneration

    Get PDF
    BACKGROUND: Progressive neuron loss in the frontal and temporal lobes of the cerebral cortex typifies frontotemporal lobar degeneration (FTLD). FTLD sub types are classified on the basis of neuronal aggregated protein deposits, typically containing either aberrantly phosphorylated TDP-43 or tau. Our recent work demonstrated that tau tubulin kinases 1 and 2 (TTBK1/2) robustly phosphorylate TDP-43 and co-localize with phosphorylated TDP-43 in human postmortem neurons from FTLD patients. Both TTBK1 and TTBK2 were initially identified as tau kinases and TTBK1 has been shown to phosphorylate tau epitopes commonly observed in Alzheimer's disease and other tauopathies. METHODS: To further elucidate how TTBK1/2 activity contributes to both TDP-43 and tau phosphorylation in the context of the neurodegeneration seen in FTLD, we examined the consequences of elevated human TTBK1/2 kinase expression in transgenic animal models of disease. RESULTS: We show that C. elegans co-expressing tau/TTBK1 tau/TTBK2, or TDP-43/TTBK1 transgenes in combination exhibit synergistic exacerbation of behavioral abnormalities and increased pathological protein phosphorylation. We also show that C. elegans co-expressing tau/TTBK1 or tau/TTBK2 transgenes in combination exhibit aberrant neuronal architecture and neuron loss. Surprisingly, the TTBK2/TDP-43 transgenic combination showed no exacerbation of TDP-43 proteinopathy related phenotypes. Additionally, we observed elevated TTBK1/2 protein expression in cortical and hippocampal neurons of FTLD-tau and FTLD-TDP cases relative to normal controls. CONCLUSIONS: Our findings suggest a possible etiology for the two most common FTLD subtypes through a kinase activation driven mechanism of neurodegeneration

    Enabling nanomaterial, nanofabrication and cellular technologies for nanoneuromedicines

    Get PDF
    Nanoparticulate delivery systems represent an area of particular promise for nanoneuromedicines. They possess significant potential for desperately needed therapies designed to combat a range of disorders associated with aging. As such, the field was selected as the focus for the 2014 meeting of the American Society for Nanomedicine. Regenerative, protective, immune modulatory, anti-microbial and anti-inflammatory products, or imaging agents are readily encapsulated in or conjugated to nanoparticles and as such facilitate the delivery of drug payloads to specific action sites across the blood-brain barrier. Diagnostic imaging serves to precisely monitor disease onset and progression while neural stem cell replacement can regenerate damaged tissue through control of stem cell fates. These, taken together, can improve disease burden and limit systemic toxicities. Such enabling technologies serve to protect the nervous system against a broad range of degenerative, traumatic, metabolic, infectious and immune disorders

    Placental adaptations in growth restriction

    Get PDF
    The placenta is the primary interface between the fetus and mother and plays an important role in maintaining fetal development and growth by facilitating the transfer of substrates and participating in modulating the maternal immune response to prevent immunological rejection of the conceptus. The major substrates required for fetal growth include oxygen, glucose, amino acids and fatty acids, and their transport processes depend on morphological characteristics of the placenta, such as placental size, morphology, blood flow and vascularity. Other factors including insulin-like growth factors, apoptosis, autophagy and glucocorticoid exposure also affect placental growth and substrate transport capacity. Intrauterine growth restriction (IUGR) is often a consequence of insufficiency, and is associated with a high incidence of perinatal morbidity and mortality, as well as increased risk of cardiovascular and metabolic diseases in later life. Several different experimental methods have been used to induce placental insufficiency and IUGR in animal models and a range of factors that regulate placental growth and substrate transport capacity have been demonstrated. While no model system completely recapitulates human IUGR, these animal models allow us to carefully dissect cellular and molecular mechanisms to improve our understanding and facilitate development of therapeutic interventions

    Diagnosing Acute Compartment Syndrome – where have we got to?

    Get PDF
    Open Access via the Springer Compact AgreementPeer reviewedPublisher PD

    MOOSE MOVEMENT PATTERNS IN THE UPPER KOYUKUK RIVER DRAINAGE, NORTHCENTRAL ALASKA

    Get PDF
    Understanding movement patterns of moose (Alces alces) is critical to understanding their ecology and sound management. Our study was prompted by concern that the Dalton Highway Corridor Management Area (DHCMA), where the Dalton Highway facilitates access for non-local hunting, may be a population sink for moose that also reside in more remote and protected areas like Gates of the Arctic National Park and Preserve (GAAR) and Kanuti National Wildlife Refuge (KNWR). We did not detect substantial migrations between DHCMA and GAAR or KNWR. However, we estimated that 14–60% of moose in our study area were migratory depending on sex, location within our study area, and methodology utilized to differentiate migratory behavior. A quarter of the animals displayed mixed-migratory strategies where migration is exhibited by a single individual in some years but not others. The percentage of moose that were migratory in our study population, and the distances they migrated, were lower than reported from studies elsewhere in interior Alaska. We hypothesize this may be related to their very low density (∼ 0.1 moose/km2) and/or higher terrain ruggedness in part of the study area. Winter severity did not appear to impact migration, but home range sizes were smaller in severe winters
    corecore