Saint Mary's University

About: Saint Mary's University is a education organization based out in Halifax, Nova Scotia, Canada. It is known for research contribution in the topics: Population & Stars. The organization has 1931 authors who have published 4993 publications receiving 143226 citations.

Geochemistry of Precambrian ophiolites from Bou Azzer, Morocco

Abstract: The Upper Proterozoic ophiolite complex of Bou Azzer, Morocco, includes ultramafic rocks, cumulate gabbros, sheeted dykes, pillow lavas and diorite-quartz diorite intrusions and an overlying volcano-sedimentary sequence. The gabbroic cumulates, basaltic flows and dykes have compositions similar to recent ocean-floor rocks (N- and/or T-type). Among other features, they have comparable light REE-depleted patterns and relations of Ti-Zr and La-Nb. Although fractional crystallization played an important role in the evolution of these rocks, the large variations in their chemical compositions require generation from a heterogeneous upper mantle source and/or by a dynamic partial melting process. Diorites, quartz diorites and the volcanic rocks of the overlying sequence are calc-alkaline, genetically unrelated to the tholeiitic suite and indicative of an island arc setting. A possible tectonic model for the ophiolite complex is a marginal basin just behind a still active island arc.

Winter Flounder Expressed Sequence Tags: Establishment of an EST Database and Identification of Novel Fish Genes.

Abstract: An EST database of more than 900 sequences has been constructed from complementary DNAs from six different tissues (stomach, intestine, pyloric cecum, liver, spleen, and ovary) of the winter flounder Pleuronectes americanus. Template preparation and automated sequencing were optimized to generate high-quality information in an economic fashion. Using computer scripts developed in our laboratory, the sequences were automatically compared with sequences in the databases via a Web-browser interface, and significant returns were recorded and organized on user-friendly HTML pages. Half (453) of the ESTs had significant matches to database sequences of known function, 33 matched ESTs from other organisms, 34 matched ribosomal RNAs, and 24 matched hypothetical open reading frames of unknown function. Forty-one percent (374) of the ESTs had no matches to sequences in the database and presumably represent previously unidentified cDNAs. Several sequences are the first isolated from teleost fish, and should be of interest for gene mapping and studies of developmental biology.

Numerical simulations of astrophysical jets from Keplerian discs — III. The effects of mass loading

Abstract: We present 2.5D time-dependent simulations of the non-linear evolution of non-relativistic outflows from the surface of Keplerian accretion discs. The gas is accelerated from the surface of the disc (which is a fixed platform in these simulations) into a cold corona in stable hydrostatic equilibrium. We explore the dependence of the resulting jet characteristics upon the mass loading of the winds. Two initial configurations of the threading disc magnetic field are studied: a potential field and a uniform vertical field configuration. We show that the nature of the resulting highly collimated, jet-like outflows (steady or episodic) is determined by the mass load of the disc wind. The mass load controls the interplay between the collimating effects of the toroidal field and the kinetic energy density in the outflow. In this regard, we demonstrate that the onset of episodic behaviour of jets appears to be determined by the quantity which compares the speed for a toroidal Alfven wave to cross the diameter of the jet, with the flow speed vp along the jet. This quantity decreases with increasing load. For sufficiently large N (small mass loads), disturbances appear to grow leading to instabilities and shocks. Knots are then generated and the outflow becomes episodic. These effects are qualitatively independent of the initial magnetic configuration that we employed and are probably generic to a wide variety of magnetized accretion disc models.

The γ-ray binary LS 5039: mass and orbit constraints from MOST observations

Abstract: The results of a coordinated space-based photometric and ground-based spectroscopic observing campaign on the enigmatic γ -ray binary LS 5039 are reported. 16 d of observations from the MOST satellite have been combined with high-resolution optical echelle spectroscopy from the 2.3-m ANU Telescope in Siding Spring, Australia. These observat ions were used to measure the orbital parameters of the binary and to study the properties of stellar wind from the O primary. We found that any broad-band optical photometric variability at the orbital period is below the 2 mmag level, supporting the scenario that the orbital eccentricity of the system is near the 0.24 ± 0.08 value implied by our spectroscopy, which is lower than values previously obtained by other workers. The low amplitude optical variability also implies the component masses are at the higher end of estimates based on the primary’s O6.5V((f)) spectral type with