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Root traits influence stormwater performance in a green roof microcosm
Get PDFviii, 47 leaves : colour illustrations ; 29 cmIncludes abstract.Includes bibliographical references (leaves 39-47).Water uptake from vegetation can govern plant productivity through different mechanisms in natural terrestrial ecosystems. However, the ability of plants to regulate water can be viewed as an ecosystem service in urban regions, where vegetation in constructed ecosystems can help reduce stormwater runoff through their root systems. However, there is no knowledge on how root traits operate in extensive green roofs, an increasingly popular form of green infrastructure, as the substrate environment has an extremely shallow substrate depth (~20 cm) and a lack of biological legacy. In this study, I found that stormwater performance is not solely a function of rooting depth; rather, a multitude of belowground traits govern water regulation in this novel ecosystem that may optimize transport capacity, soil exploration and root construction costs. Overall, this study parallels findings from natural ecosystems and provides practitioners with new tools to create a more functional green roof
Nutritional status in Nepal : analyzing the determinants of nutritional outcomes along the distribution
Get PDF1 online resource (26 p.) : colour illustrationsIncludes abstract.Includes bibliographical references (p. 23-26).Undernutrition in very young children can have long lasting effects for them personally, as well as for the economy that is impacted by their lowered human capital formation. Despite its higher than average undernutrition rate, Nepal’s undernutrition problem has rarely been studied. Using Nepal Demographic and Health Surveys 2016, a nationally representative survey, this paper conducts OLS and quantile regression analyses at the 25th, 50th, and 75th percentiles to shed light on the determinants of undernutrition. This study finds that the ecological zone in which a child lives can have a great impact on their nutritional status, with children from mountainous areas being more prone to stunting, and children from the terai being at a far greater risk of wasting, holding everything else constant. Additionally, wealth is found to have a strong effect on a child’s height-for-age z-scores, indicating that access to resources is an important determinant for this measure of nutritional status. This is the first paper to use the quantile regression approach in Nepal, and the most recent study to observe the effects of nutrition on Nepal as a whole
2019-07-25 Senate Minutes and Agenda
No full textMinutes and agenda for the July 25th, 2019 meeting of Saint Mary's University Senate
Number density distribution of satellite galaxies around massive central galaxies in CLAUDS + HSC at 0.3 < z < 0.9
Get PDFxv, 99 leaves : colour illustrations ; 29 cmIncludes abstract and appendix.Includes bibliographical references (leaves 91-99).Satellite galaxies around massive central galaxies can provide important information about galactic environmental effect. In this thesis, we selected thousands of massive (log(Mcen/M☉) > 11.15) central galaxies using wide and deep imaging data at 0.3 < z < 0.9 and investigated radial number density distribution of the satellites. The distribution of satellites can be described by the NFW profile at large projected radii but deviates from it in inner regions (within ∼100 kpc). We found that low-massive satellite galaxies (9.5 < log(Msat/M☉) < 10.2) have more significant deviation from the NFW than high-mass (log(Msat/M☉) > 10.2). For central galaxy dependence, we found galaxy conformity signal and that the number of satellites increases with central mass. Redshift evolution enhances number density in inner regions more significantly than in outer regions. We propose that shape of the satellite distribution is related to migration, involving effects such as dynamical friction and tidal stripping. We compared our results with the IllustrisTNG simulation
Identifying pollinator communities visiting berry-producing plants on coastal barrens
Get PDF1 online resource (49 p.) : illustrations (some colour)Includes abstract.Includes bibliographical references (p. 46-49).There is a lack of research on the pollinator communities of flowering plant species within coastal barren habitats. This study examined four closely related plant species in the Ericaceae that have a similar flower structure: Vaccinium angustifolium, Gaylussacia baccata, Gaylussacia bigeloviana, and Gaultheria procumbens. They were studied at four coastal barren sites within Halifax County, Nova Scotia. At each site, pollinator collection and observations were carried out, as well as vegetation surveys to identify available foraging resources. Pollinators were identified down to morphospecies. A total of 145 insect pollinators, comprised of 32 morphospecies were collected. Results identified pollinator assemblages. There were significant correlations between all pollinator variables (catches, visits, richness) and the number of flowers on the target species. G. baccata and G. bigeloviana displayed higher pollinator diversity and had significantly more flowers than the other two target plant species. This study is one of the first to document and record pollinator communities of berry-producing plant species and underlines the importance of understanding plant-pollinator interactions
Undergraduate students accessing mental health services : exploring the barriers surmounted using a qualitative approach
Get PDFviii, 91 leaves : colour illustrations ; 29 cmIncludes abstract and appendices.Includes bibliographical references (leaves 76-81).There is a high prevalence of mental health disorders among youth, however there is not a corresponding high level of help seeking behavior. Currently, there is little research on the barriers that post-secondary students have to overcome to access mental health services in Canada. This master’s thesis conducted qualitative semi-structured interviews (N=10) to gain an understanding of the barriers that undergraduate students attending an Atlantic Canadian university surmounted to access professional mental health services. The three overarching themes include; a) structural barriers to mental health services, b) barriers related to the perceptions of mental health problems, and c) barriers related to the perceptions of mental health services. Recommendations are to promote positive mental health at a community level by implementing policy and interventions such as peer support programs, gatekeeper programs, and mental health literacy workshops which have proven to increase help seeking and can be self-sustaining within the universities
A novel method for the measurement of half-lives and decay branching ratios of exotic nuclei
Get PDFPublished versionA novel method for simultaneous measurement of masses, Q-values, isomer excitation energies, half-lives and decay branching ratios of exotic nuclei has been demonstrated. The method includes first use of a stopping cell as an ion trap, combining storage of mother and daughter nuclides for variable durations in a cryogenic stopping cell (CSC), and afterwards the identification and counting of them by a multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS). We utilized our method to record the decay and growth of the 216Po and 212Pb isotopes (alpha decay) and of the 119m2Sb isomer (t1/2=850±90 ms) and 119gSb isotope (isomer transition), obtaining half-lives consistent with literature values. The amount of non-nuclear-decay losses in the CSC up to ∼10 s is negligible, which exhibits its extraordinary cleanliness. For 119Sb isotopes, we present the first direct measurements of the mass of its ground state, and the excitation energy and decay branching ratios of its second isomeric state (119m2Sb). This resolves discrepancies in previous excitation energy data, and is the first direct evidence that the 119m2Sb isomer decays dominantly via γ emission. These results pave the way for the measurement of branching ratios of exotic nuclei
Paleo-Hydrothermal Predecessor to Perennial Spring Activity in Thick Permafrost in the Canadian High Arctic, and Its Relation to Deep Salt Structures: Expedition Fiord, Axel Heiberg Island, Nunavut
Get PDFPublished versionIt is surprising to encounter active saline spring activity at a constant 6° C temperature year-round not far away from the North Pole, at latitude 79° 24′N, where the permafrost is ca. 600 m thick and average annual temperature is -15° C. These perennial springs in Expedition Fiord, Queen Elizabeth Islands, Canadian Arctic Archipelago, had previously been explained as a recent, periglacial process. However, the discovery near White Glacier (79° 26.66′N; 90° 42.20′W; 350 m.a.s.l.) of a network of veins of hydrothermal origin with a similar mineralogy to travertine precipitates formed by the springs suggests that their fluids have much deeper circulation and are related to evaporite structures (salt diapirs) that underlie the area. The relatively high minimum trapping temperature of the fluid inclusions (avg. ~200 ± 45° C, 1σ) in carbonate and quartz in the vein array, and in quartz veins west of the site, explains a local thermal anomaly detected through low-temperature thermochronology. This paper reviews and updates descriptive features of the perennial springs in Expedition Fiord and compares their mineralogy, geochemistry, and geology to the vein array by White Glacier, which is interpreted as a hydrothermal predecessor of the springs. The perennial springs in Axel Heiberg Island are known for half a century and have been extensively described in the literature. Discharging spring waters are hypersaline (1-4 molal NaCl; ~5 to 19 wt% NaCl) and precipitate Fe-sulfides, sulfates, carbonates, and halides with acicular and banded textures representing discharge pulsations. At several sites, waters and sediments by spring outlets host microbial communities that are supported by carbon- and energy-rich reduced substrates including sulfur and methane. They have been studied as possible analogs for life-supporting environments in Mars. The vein array at White Glacier consists of steep to subhorizontal veins, mineralized fractures, and breccias within a gossan area of ca. 350 × 50 m. The host rock is altered diabase and a chaotic matrix-supported breccia composed of limestone, sandstone, and anhydrite-gypsum. Mineralization consists of brown calcite (pseudomorph after aragonite) in radial aggregates as linings of fractures and cavities, with transparent, sparry calcite and quartz at the centre of larger cavities. Abundant sulfides pyrite and marcasite and minor chalcopyrite, sphalerite, and galena occur in masses and veins, much like in base metal deposits known as Mississippi Valley Type; their weathering is responsible for brown Fe oxides forming a gossan. Epidote and chlorite rim veins where the host rock is Fe- and Mg-rich diabase. The banded carbonate textures with organic matter and sulfides are reminiscent of textures observed in mineral precipitates forming in the active springs at Colour Peak Diapir. Very small fluid inclusions (5-10 μm) in two generations of vein calcite (hexagonal, early brown calcite we denominate “cal1” lining vein walls; white-orange sparry calcite “cal2” infilling veins) have bulk salinities that transition between an early, high-salinity end-member brine (up to ~20 wt% NaCl equivalent) to a later, low-salinity end-member fluid (nearly pure water) and show large fluctuations in salinity with time. Inclusions that occupy secondary planes and also growth zones in the later calcite infilling (deemed primary) have Th ranging from 100° C to 300° C (n = 120, average~200° C; independent of salinity), 2 orders of magnitude higher than average discharging water temperatures of 6° C at Colour Peak Diapir. Carbon isotope composition (δ13CVPDB) of the White Glacier vein array carbonates ranges from approximately -20 to -30‰, like carbonates formed by the degradation of petroleum, whereas carbonates at Colour Peak Diapir springs have a value of -10‰. Oxygen isotope composition (δ18OVSMOW) of vein carbonates ranges from -0.3‰ to +3.5‰, compatible with a coeval fluid at 250° C with a composition from -3.5‰ to -7.0‰. These data are consistent with carbonates having precipitated from mixtures of heated formational waters and high-latitude meteoric waters. In contrast, the δ18OVSMOW value for carbonates at Colour Peak Diapir springs is +10‰, derived from high-latitude meteoric waters at 6° C. The sulfur isotope (δ34SVCDT) composition of Fe-sulfides at the perennial springs is +19.2‰, similar to the δ34SVCDT of Carboniferous-age sulfate of the diapirs and consistent with lowtemperature microbial reduction of finite (closed-system) sulfate. The δ34SVCDT values of Fe-sulfides in the vein array range from -2.7‰ to +16.4‰, possibly reflecting higher formation temperatures involving reduction of sulfate by organics. We suggest that the similar setting, mineralogical compositions, and textures between the hydrothermal vein array and the active Colour Peak Diapir springs imply a kinship. We suggest that overpressured basinal fluids expelled from the sedimentary package and deforming salt bodies at depth during regional compressional tectonic deformation ca. 50 million years ago (Eocene) during what is known as the Eurekan Orogeny created (by hydrofracturing) the vein array at White Glacier (and probably other similar ones), and the network of conduits created continued to be a pathway around salt bodies for deeply circulating fluids to this day. Fluid inclusion data suggest that the ancient conduit system was at one point too hot to support life but may have been since colonized by microorganisms as the system cooled. Thermochronology data suggest that the hydrologic system cooled to temperatures possibly sustaining life about 10 million years ago, making it since then a viable analogue environment for the establishment of microbial life in similar situations on other planets
Controlling the Thermal Stability and Volatility of Organogold(I) Compounds for Vapor Deposition with Complementary Ligand Design
Get PDFSubmitted versionAtomic layer deposition (ALD) of gold is being studied by multiple research groups, but to date no process using non-energetic co-reactants has been demonstrated. In order to access milder co-reactants, precursors with higher thermal stability are required. We set out to uncover how structure and bonding affect the stability and volatility of a family of twelve organogold(I) compounds using a combination of techniques: X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and density functional theory (DFT). Small, unsubstituted phosphonium ylide ligands bind more strongly to Au(I) than their silyl-substituted analogues, but the utility of both these ligands suffers due to their poor volatility and substantial thermal decomposition. Pentafluorophenyl (C6F5) is introduced as a new, very electronegative ligand for gold vapor deposition precursors, and it was found that the disadvantage to volatility due to π-stacking and other intermolecular interactions in the solid state was overshadowed by dramatic improvements to kinetic and thermodynamic stability. We introduce a new figure of merit to compare and rank the suitability of these and other complexes as precursors for vapor deposition. Finally, DFT calculations on four compounds that have high figures of merit show a linear correlation between the gold-coordinative ligand bond dissociation energies and the observed decomposition temperatures, highlighting and justifying this design strategy
A global comparison of community-based responses to natural hazards
Get PDFPublished versionCommunity-based disaster preparedness is an important component of disaster management. Knowledge of interventions that communities utilize in response to hazards is important to develop local-level capacity and increase community resilience. This paper systematically examines empirical information about local-level responses to hazards based on peer-reviewed, published case studies. We developed a data set based on 188 articles providing information from 318 communities from all regions of the world. We classified response examples to address four key questions: (i) what kinds of responses are used by communities all over the world? (ii) Do communities in different parts of the world use different kinds of responses? (iii) Are communities using hazard-specific responses? (iv) Are communities using a multi-hazard approach? We found that within an extensive literature on hazards, there is relatively little empirical information about community-based responses to hazards. Across the world, responses aiming at securing basic human needs are the most frequently reported kinds of responses. Although the notion of community-based disaster preparedness is gaining importance, very few examples of responses that draw on the social fabric of communities are reported. Specific regions of the world are lacking in their use of certain hazard responses classes. Although an all-hazard approach for disaster preparedness is increasingly recommended, there is a lack of multi-hazard response approaches on the local level