University of Victoria

About: University of Victoria is a education organization based out in Victoria, British Columbia, Canada. It is known for research contribution in the topics: Population & Galaxy. The organization has 14994 authors who have published 41051 publications receiving 1447972 citations. The organization is also known as: Victoria College.

A Biogeographical Perspective of the Deep-Sea Hydrothermal Vent Fauna

Abstract: Biogeography seeks to distinguish patterns in the distribution of species and to determine causal processes. Hydrothermal vent habitats have several properties that invite biogeographic studies: constrained to active deep-sea ocean ridges, known in most oceans and anticipated in the rest, patchy in distribution, extreme conditions and a limited group of inhabitants. Biologists have studied 30 vent sites mostly in the Pacific and Atlantic. Currently, 443 invertebrate species are known to generic level although many more are under study. Additionally, 32 octopus and fish species are observed in and around vents. The faunas of other sulphide-rich deep-water habitats such as margin cold seeps and organic masses (wood, carcasses) do not show great affinity at the species level to the vent fauna but the higher taxonomic affiliations suggest close evolutionary ties for many groups. Many studies address the formation of regional faunas using the first- known sites on the Galapagos Rift and northern East Pacific Rise as the major sites of comparison. Physical disjunction of ridge crests is a likely factor in promoting the extensive provinciality that currently exists. Nonetheless, faunas on two sides of the Pacific and in the Atlantic have closer relations to each other than to the nearby “normal” deep-sea fauna. At the individual ridge scale, extensive gene flow among separated populations occurs in many species and serves to maintain the regional species pool. However, major discontinuities between major ridges reduce or eliminate gene flow; vicariant processes appear to be important. The role of differing rates of spreading in different provinces and the concomitant effects on vent habitats and faunas need further investigation. Over 75% of vent species occur at only one site and none occur at all sites. Examination of the reproductive characters of some widespread species reveals no special dispersal strategy nor does reproductive strategy predict the extent of distribution. Vestimentiferan tubeworm species are highly endemic and found only at Pacific vents; their limited spread may be a result of recent entry into the habitat. Alvinellid polychaete cladogenetic pattern does not match geographic regions, indicating independent penetration by numerous lineages. Endemicity among vent gastropods is high with over 60% of genera limited to this habitat; many affiliations with other sulphide-rich habitats can be identified. Among the vent gastropods there are some lineages that may have entered the vent habitat in the Mesozoic. Hydrothermal vents provide a good testing ground for processes that control patterns in diversity. Ecological and historical controls at both local and regional scales can be discerned with further study.

Water-Soluble GdF3 and GdF3/LaF3 NanoparticlesPhysical Characterization and NMR Relaxation Properties

Abstract: Nanoparticles consisting of either a solid core of GdF3 or an 80/20 mixture of GdF3 and LaF3 have been prepared for use as NMR and MRI relaxation agents. To obtain high aqueous solubilities, the particles were coated with either citrate (cit) groups (in the case of GdF3 nanoparticles), giving the nanoparticle a negatively charged surface, or 2-aminoethyl phosphate (AEP) groups (in the case of GdF3/LaF3 = 80/20), giving the nanoparticle a positively charged surface at physiological pH. In the presence of the 80/20 GdF3/LaF3:AEP, the paramagnetic contribution to the water spin−lattice relaxation rate was observed to be 7.5 s-1 at a nanoparticle concentration of 9.0 nM (0.78 mg/mL, 25 °C, 600 MHz 1H Larmor frequency). Similarly, paramagnetic rates of 10.5 s-1 were observed for water using the GdF3:cit nanoparticles at a nanoparticle concentration of 0.55 nM (0.77 mg/mL, 25 °C, 600 MHz 1H Larmor frequency). Relaxivity measurements confirmed the potential of the particles for applications as contrast agents at...

Small Acts of Living: Everyday Resistance to Violence and Other Forms of Oppression

Abstract: The author describes an approach to therapy which is based on the observation that whenever persons are badly treated, they resist. Case illustrations are given in which individuals seeking therapy had been subjected to violence and oppression.

Apatite Trace Element Compositions: A Robust New Tool for Mineral Exploration

Abstract: Apatites from the major types of mainly magmatic-hydrothermal mineral deposits (30 localities, mostly in British Columbia, Canada) together with apatites from carbonatites (29 intrusive complexes) and unmineralized rocks (11 localities) have been analyzed by electron microprobe and laser ablation-inductively coupled plasma mass spectrometry. Discriminant analysis using Mg, V, Mn, Sr, Y, La, Ce, Eu, Dy, Yb, Pb, Th, and U reveals that apatites from mineral deposits can be distinguished from apatites in carbonatites and unmineralized rocks. Apatites from mineral deposits are characterized by higher Ca and correspondingly lower total contents of trace elements that partition onto the Ca sites (rare earth elements (REEs), Y, Mn, Sr, Pb, Th, and U) than apatites from unmineralized rocks and carbonatites. Apatites from the different deposit types also have distinct trace element compositions that are readily discriminated by the discriminant functions. Apatites from worldwide carbonatites have the most fractionated REE distributions with light REE enrichment (Ce/Yb CN = 35–872), high V (1.6–1,466 ppm), Sr (1,840–22,498 ppm), Ba (1.8–275 ppm), and Nb (0.4–19 ppm) contents, the lowest W contents (0.05–0.55 ppm), and no significant Eu anomalies (Eu/Eu* = 0.9–1.2). Apatites from alkalic porphyry Cu-Au deposits in the North American Cordillera possess high V contents (2.5–337 ppm), whereas apatites from calc-alkaline porphyry Cu-Au and Cu-Mo deposits have high Mn contents (334–10,934 ppm) and typically large negative Eu anomalies (Eu/Eu* = 0.2–1.1). Apatites from iron oxide Cu-Au (IOCG) and related Kiruna-type iron oxide-apatite (IOA) deposits in Canada, China, and Mexico typically have large negative Eu anomalies (Eu/Eu* = 0.2–1.5) and low Mn contents (40–5,753 ppm). Apatites from orogenic Ni-Cu, porphyryrelated Cu-Au breccia, Au-Co skarn, Pb-Zn skarn, and Cu skarn deposits have relatively low abundances of impurity cations. This study demonstrates that detrital apatite grains collected during regional geochemical surveys are effective in identifying specific types of buried mineral deposits in glaciated terranes.

The large- and small-scale structures of dust in the star-forming perseus molecular cloud

Abstract: We present an analysis of ~3.5 deg2 of submillimeter continuum and extinction data of the Perseus molecular cloud. We identify 58 clumps in the submillimeter map, and we identify 39 structures ("cores") and 11 associations of structures ("super cores") in the extinction map. The cumulative mass distributions of the submillimeter clumps and extinction cores have steep slopes (α ~ 2 and 1.5-2, respectively), steeper than the Salpeter initial mass function (IMF; α = 1.35), while the distribution of extinction super cores has a shallow slope (α ~ 1). Most of the submillimeter clumps are well fit by stable Bonnor-Ebert spheres with 10 K 5-7 mag), although Bonnor-Ebert models suggest that we should have been able to detect them at lower column densities if they exist. These observations provide a stronger case for an extinction threshold than that found in analysis of less sensitive observations of the Ophiuchus molecular cloud (Johnstone et al.). The relationship between submillimeter clumps and their parent extinction core has been analyzed. The submillimeter clumps tend to lie offset from the larger extinction peaks, suggesting that the clumps formed via an external triggering event, consistent with previous observations.