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.

Complex gas hydrate from the Cascadia margin

Abstract: Natural gas hydrates — ice-like solids that consist of 'guest' molecules trapped in cages of water molecules — are a potential source of energy and may play a role in climate change and seafloor collapse. Experiments have shown that there are three common gas hydrate structures — sI, sII and sH — but only sI and sII hydrate have been found in the natural environment. Now sH hydrate (in close association with sII hydrate) has been identified in seafloor samples from Barkley canyon, 80 km off Vancouver Island. This complex gas hydrate can trap larger guest molecules than sI or sII, and is more stable than sI hydrate, indicating that gas hydrates could be more widely distributed than previously thought. The discovery of sH hydrate in a sample from Barkley Canyon marks the first time this hydrate has been found in the natural environment. This complex gas hydrate can trap larger guest molecules than sI or sII hydrate, and is stable at higher temperatures and pressures than sI hydrate, indicating that gas hydrates could be more widely distributed than previously thought. Natural gas hydrates are a potential source of energy1 and may play a role in climate change2 and geological hazards3. Most natural gas hydrate appears to be in the form of ‘structure I’, with methane as the trapped guest molecule4, although ‘structure II’ hydrate has also been identified, with guest molecules such as isobutane and propane, as well as lighter hydrocarbons5,6. A third hydrate structure, ‘structure H’, which is capable of trapping larger guest molecules, has been produced in the laboratory7, but it has not been confirmed that it occurs in the natural environment. Here we characterize the structure, gas content and composition, and distribution of guest molecules in a complex natural hydrate sample recovered from Barkley canyon, on the northern Cascadia margin8. We show that the sample contains structure H hydrate, and thus provides direct evidence for the natural occurrence of this hydrate structure. The structure H hydrate is intimately associated with structure II hydrate, and the two structures contain more than 13 different hydrocarbon guest molecules. We also demonstrate that the stability field of the complex gas hydrate lies between those of structure II and structure H hydrates, indicating that this form of hydrate is more stable than structure I and may thus potentially be found in a wider pressure–temperature regime than can methane hydrate deposits.

A systematic review of dropout from organized sport among children and youth

Abstract: Leisure constraints theory was used as a framework to systematically review factors associated with dropout of organized sport among children and adolescents. Keyword searches for the population, context and construct of interest (i.e. dropout) identified articles from the entire contents of the following databases: Academic Search Complete, ERIC, MEDLINE, PsycINFO and SPORTDiscus. The initial search yielded 557 studies, and 43 met the selection criteria. Most studies focused solely on adolescents, and 89% of participants were male. Most studies were cross-sectional using quantitative approaches. Almost 30 different sports were included in the reviewed studies; however, the most represented sports were soccer, swimming, gymnastics and basketball. Findings from this review indicated that intrapersonal and interpersonal constraints are more frequently associated with dropping out of sport than structural constraints. Although many discrete factors associated with dropout were identified, five major areas em...

Genome-wide and expression analysis of protein phosphatase 2C in rice and Arabidopsis

Abstract: The protein phosphatase 2Cs (PP2Cs) from various organisms have been implicated to act as negative modulators of protein kinase pathways involved in diverse environmental stress responses and developmental processes. A genome-wide overview of the PP2C gene family in plants is not yet available. A comprehensive computational analysis identified 80 and 78 PP2C genes in Arabidopsis thaliana (AtPP2Cs) and Oryza sativa (OsPP2Cs), respectively, which denotes the PP2C gene family as one of the largest families identified in plants. Phylogenic analysis divided PP2Cs in Arabidopsis and rice into 13 and 11 subfamilies, respectively, which are supported by the analyses of gene structures and protein motifs. Comparative analysis between the PP2C genes in Arabidopsis and rice identified common and lineage-specific subfamilies and potential 'gene birth-and-death' events. Gene duplication analysis reveals that whole genome and chromosomal segment duplications mainly contributed to the expansion of both OsPP2Cs and AtPP2Cs, but tandem or local duplication occurred less frequently in Arabidopsis than rice. Some protein motifs are widespread among the PP2C proteins, whereas some other motifs are specific to only one or two subfamilies. Expression pattern analysis suggests that 1) most PP2C genes play functional roles in multiple tissues in both species, 2) the induced expression of most genes in subfamily A by diverse stimuli indicates their primary role in stress tolerance, especially ABA response, and 3) the expression pattern of subfamily D members suggests that they may constitute positive regulators in ABA-mediated signaling pathways. The analyses of putative upstream regulatory elements by two approaches further support the functions of subfamily A in ABA signaling, and provide insights into the shared and different transcriptional regulation machineries in dicots and monocots. This comparative genome-wide overview of the PP2C family in Arabidopsis and rice provides insights into the functions and regulatory mechanisms, as well as the evolution and divergence of the PP2C genes in dicots and monocots. Bioinformatics analyses suggest that plant PP2C proteins from different subfamilies participate in distinct signaling pathways. Our results have established a solid foundation for future studies on the functional divergence in different PP2C subfamilies.

The Formation of a Realistic Disk Galaxy in Λ-dominated Cosmologies

Abstract: We simulate the formation of a realistic disk galaxy within the hierarchical scenario of structure formation and study its internal properties to the present epoch. We use a set of smoothed particle hydrodynamic (SPH) simulations, with a high dynamical range and force resolution, that include cooling, star formation, supernovae (SNe) feedback and a redshift-dependent UV background. We compare results from a Λ cold dark matter (ΛCDM) simulation to a Λ warm dark matter (ΛWDM) (2 keV) simulation that forms significantly less small-scale structure. We show how high mass and force resolution in both the gas and dark-matter components play an important role in solving the angular momentum catastrophe claimed from previous simulations of galaxy formation within the hierarchical framework. Hence, a large disk forms without the need of strong energy injection, the z = 0 galaxies lie close to the I band Tully-Fisher relation, and the stellar material in the disk component has a final specific angular momentum equal to 40% and 90% of the dark halo in the ΛCDM and ΛWDM models, respectively. If rescaled to the Milky Way, the ΛCDM galaxy has an overabundance of satellites, with a total mass in the stellar halo 40% of that in the bulge+disk system. The ΛWDM galaxy has a drastically reduced satellite population and a negligible stellar spheroidal component. Encounters with satellites play only a minor role in disturbing the disk. Satellites possess a variety of star formation histories linked to mergers and pericentric passages along their orbit around the primary galaxy. In both cosmologies, the galactic halo retains most of the baryons accreted and builds up a hot gas phase with a substantial X-ray emission. Therefore, while we have been successful in creating a realistic stellar disk in a massive galaxy within the ΛCDM scenario, energy injection emerges as necessary ingredient to reduce the baryon fraction in galactic halos, independent of the cosmology adopted.

Physics Beyond Colliders at CERN: Beyond the Standard Model Working Group Report

Abstract: The Physics Beyond Colliders initiative is an exploratory study aimed at exploiting the full scientific potential of the CERN's accelerator complex and scientific infrastructures through projects complementary to the LHC and other possible future colliders. These projects will target fundamental physics questions in modern particle physics. This document presents the status of the proposals presented in the framework of the Beyond Standard Model physics working group, and explore their physics reach and the impact that CERN could have in the next 10-20 years on the international landscape.