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Antigonish, Canada

St. Francis Xavier University is a primarily undergraduate university located in Antigonish, Nova Scotia, Canada. The university brings together 5,100 students from across Canada and around the world in arts, science, business and information systems. It is a member of the U4 League, a group of primarily undergraduate universities in Eastern Canada. Wikipedia.

Perry C.G.R.,York University | Kane D.A.,St. Francis Xavier University | Lanza I.R.,Rochester College | Neufer P.D.,East Carolina University
Diabetes | Year: 2013

A growing body of research is investigating the potential contribution of mitochondrial function to the etiology of type 2 diabetes. Numerous in vitro, in situ, and in vivo methodologies are available to examine various aspects of mitochondrial function, each requiring an understanding of their principles, advantages, and limitations. This review provides investigators with a critical overview of the strengths, limitations and critical experimental parameters to consider when selecting and conducting studies on mitochondrial function. In vitro (isolated mitochondria) and in situ (permeabilized cells/tissue) approaches provide direct access to the mitochondria, allowing for study of mitochondrial bioenergetics and redox function under defined substrate conditions. Several experimental parameters must be tightly controlled, including assay media, temperature, oxygen concentration, and in the case of permeabilized skeletal muscle, the contractile state of the fibers. Recently developed technology now offers the opportunity to measure oxygen consumption in intact cultured cells. Magnetic resonance spectroscopy provides the most direct way of assessing mitochondrial function in vivo with interpretations based on specific modeling approaches. The continuing rapid evolution of these technologies offers new and exciting opportunities for deciphering the potential role of mitochondrial function in the etiology and treatment of diabetes. © 2013 by the American Diabetes Association. Source

Murphy J.B.,St. Francis Xavier University
Earth-Science Reviews | Year: 2013

The appinite suite of rocks offers a unique opportunity to study the effect of water on the generation, emplacement and crystallization history of mafic to felsic magma. The suite consists of a group of coeval plutonic and/or hypabyssal rocks, ranging from ultramafic to felsic in composition in which hornblende is the dominant mafic mineral, and typically occurs both as large prismatic phenocrysts and in the finer grained matrix. The suite is also characterized by abundant evidence for mixing and mingling between diverse magma types and variable degrees of contamination by host rock.Field observations corroborate experimental and theoretical studies that the hornblende stability field expands at the expense of olivine and pyroxene with increasing pH2O in the magma. Textures characteristic of appinites are consistent with rapid growth and with experimental evidence for the reduced viscosity of melts allowing efficient migration of ions to the sites of mineral growth.The appinite suite was originally defined in the Paleozoic Caledonide orogen in Scotland, where it occurs as a number of small shallow crustal bodies that were emplaced after the cessation of subduction and in the immediate aftermath of terrane collision and closure of the Iapetus Ocean. The mafic component is thought to have been triggered by asthenospheric upwelling following stab break-off, and magmas produced have both juvenile and sub-continental lithospheric mantle components. Its compositions have affinities with shoshonites. The felsic components include large batholiths that were probably derived by fractional crystallization.Other appinite suites share some, but not all of these characteristics. Appinite suites apparently range in age from Neo-Archean to Recent, and occur at all crustal levels, at depths of up to 40. km. In addition to shoshonites, appinite suites share some similar geochemical features with high-Mg andesites, sanukitoids and adakites. Some common tectonic traits include a tendency to form soon after the cessation of subduction, and the important role of deep crustal faults as conduits for magmas of various compositions to rise towards the surface. These conduits provide the setting for magmas of diverse composition to mix and mingle. Neo-Archean appinites, and their genetic relationship with abundant coeval sanukitoids, have been interpreted as evidence for the existence of some form of plate tectonics at that time.Melting may be triggered by asthenospheric upwelling caused either by slab breakoff (e.g. after terrane or continental collision) or by the generation of a slab window (e.g. where a ridge collides with a subduction zone). Mafic magma may contain a juvenile component, but Nd isotopic data suggest the additional involvement of a sub-continental lithospheric mantle that, in many instances, was previously metasomatized by fluids and magma and was underplated by mafic complexes during subduction. The composition of the mafic magma may vary from one suite to another. In several suites, the mafic magmas have more traditional calc alkalic or tholeiitic affinities and do not share the shoshonitic characteristics of the type area. In addition, in several appinite complexes, felsic magma was formed by crustal anatexis, rather than fractional crystallization. © 2013 Elsevier B.V. Source

Maletz J.,St. Francis Xavier University
Palaeontology | Year: 2010

The virgellar spine is one of the most consistent features of the graptolite sicula. It is present in a large number of graptoloid groups, but evolved separately and independently in these as it is seen from the presence of the spine in either ventral (Axonophora) or dorsal (Phyllograptus, Xiphograptus) position. The evolution of the virgellar spine in the Pan-Bireclinata in the Upper Dapingian to Lower Darriwilian time interval is known to follow four main steps, from a simple rutellum, through a lamelliform rutellum and a lanceolate virgella to the true virgellar spine. For the xiphograptids and in Phyllograptus, the origin and early development is less well documented, but appears to follow a similar path. However, the individual stages are condensed, and a true virgellar spine emerges already in the Floian time interval. A virgellar spine was found in Didymograptellus bifidus, necessitating a revision of the diagnosis of the genus Didymograptellus. A number of species of the virgellate genera Xiphograptus, Yutagraptus and Didymograptellus are described from isolated material for the first time. The species are useful for the biostratigraphic correlation of endemic mid-continent North American faunas with the Pacific Type faunal realm. Xiphograptus artus sp. nov., Didymograptellus primus sp. nov. and Didymograptellus cowheadensis sp. nov. from the Cow Head Group of western Newfoundland are described as new. © The Palaeontological Association. Source

Nance R.D.,Ohio University | Murphy J.B.,St. Francis Xavier University | Santosh M.,China University of Geosciences | Santosh M.,Kochi University
Gondwana Research | Year: 2014

The recognition that Earth history has been punctuated by supercontinents, the assembly and breakup of which have profoundly influenced the evolution of the geosphere, hydrosphere, atmosphere and biosphere, is arguably the most important development in Earth Science since the advent of plate tectonics. But whereas the widespread recognition of the importance of supercontinents is quite recent, the concept of a supercontinent cycle is not new and advocacy of episodicity in tectonic processes predates plate tectonics. In order to give current deliberations on the supercontinent cycle some historical perspective, we trace the development of ideas concerning long-term episodicity in tectonic processes from early views on episodic orogeny and continental crust formation, such as those embodied in the chelogenic cycle, through the first realization that such episodicity was the manifestation of the cyclic assembly and breakup of supercontinents, to the surge in interest in supercontinent reconstructions. We then chronicle some of the key contributions that led to the cycle's widespread recognition and the rapidly expanding developments of the past ten years. © 2013 International Association for Gondwana Research. Source

Van Zyl B.P.,St. Francis Xavier University
Journal of Physics A: Mathematical and Theoretical | Year: 2012

We present a new, simple closed form expression for the exact Wigner function of an ideal gas of harmonically trapped fermions or bosons at arbitrary temperature and dimensionality. One of the primary advantages of our expression is that it provides a clean separation of the spatial and momentum variables, which can significantly simplify analytical calculations involving the Wigner function. Our analysis is based on the explicit Fourier transform of the exact first-order density matrix, which affords an exceedingly simple derivation of the Wigner function. We demonstrate the utility of our approach by presenting several analytical results which may be trivially derived from the Wigner function, but otherwise require more involved calculations. We also examine the temperature and dimensionality dependence of the Fermi Wigner function in detail, thereby pointing out some subtle issues regarding the applicability of the Thomas-Fermi approximation to the Wigner function in the limit of a macroscopic number of particles, and finite-temperatures. © 2012 IOP Publishing Ltd. Source

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