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Grazing of ectomycorrhizae by microarthropods
Get PDFvii, 71 leaves : illustrations (some colour) ; 29 cmIncludes abstract.Includes bibliographical references (leaves 57-71).Microarthropods, including Collembola and mites, are a highly diverse and abundant group of soil animals. Previous information on interactions between microarthropods and ectomycorrhizal fungi has been mainly based on mycelium grown in pure culture. Collembola feeding preferences were assessed by offering naturally occurring ECM to the Collembola species Folsomia candida. Some ECM types, including Tricholoma aestuans, Piloderma bicolor and Suillus spraguei, were grazed. Cenococcum geophilum and Lactarius vinaceorufescens were unpalatable. However, fungi forming unpalatable ECM were grazed when not in symbiosis with the host root. To determine levels of ECM grazing occurring in the field, gut contents of a species of Folsomia and a species of Phthiracaridae were assessed molecularly. No ECM fungi were detected. Although the degree to which soil microarthropods graze ECM in the field is still unknown, this work demonstrates that there is a high degree of variation in palatability among ECM formed by different fungal species
Do egg spots influence levels of parental investment in the European Starling (Sturnus vulgaris)?
Get PDF1 online resource (20 p.) : illustrationsIncludes abstract.Includes bibliographical references (p. 18-20).Parasites can impose fitness consequences onto their hosts by reducing their reproductive success or offspring survival rates. Carnus hemapterus are external parasites that feed on the blood of European Starling (Sturnus vulgaris) nestlings and leave spots on starling eggs from their feces. Adult starlings might alter their offspring provisioning behaviours to compensate for fitness costs caused by Carnus hemapterus parasitism. I examined whether adult male European Starlings use egg spots as a cue to increase their offspring provisioning rates to offset the fitness costs of parasitism. To do so, 33 clutches were assigned to one of four groups: Control Spotted (n = 7), Control Unspotted (n = 6), Experimental Spotted (spots were added) (n = 10), and Experimental Unspotted (spots were washed off eggs) (n = 10). I predicted that nestlings hatching from clutches that were originally spotted before treatment would have lower condition. I also predicted that nestlings hatching from naturally and artificially spotted clutches would be paternally provisioned more than those from unspotted clutches. Nestling condition was determined using the residuals from regressing body mass vs. tarsus length on Day 11 of the nestling period. There was no significant difference in either nestling condition or paternal provisioning rates detected across all treatments. Carnus hemapterus did not impose any fitness costs in this population of European Starlings, and thus condition remained constant across all groups. Because of this high nestling condition, parents did not have to compensate for any harm caused by Carnus hemapterus parasitism, and as a result, fed at a similar rate as those in nests with no Carnus
Evolutionary variation in salinity tolerance among species of killifishes (Fundulus spp.)
Get PDFix, 122 leaves : illustrations (some colour), colour map ; 29 cmIncludes abstract and appendices.Includes bibliographical references (leaves 83-91).Little is known about how salinity tolerance evolves in fishes. In this study I measured salinity tolerance, and candidate mechanisms underlying tolerance, in Common Killifish (Fundulus heteroclitus), Banded Killifish (Fundulus diaphanus) and clonal F. diaphanus x F. heteroclitus F1 hybrids. To quantify tolerance, killifish acclimated to near isosmotic water (10 ppt) were transferred to 0 ppt and 32 ppt and acclimated in a stepwise manner to 60 ppt. All fish could maintain homeostasis at 0 – 32 ppt, but F. heteroclitus have an increased tolerance to 60 ppt compared to F. diaphanus and F1 hybrids, which displayed an intermediate salinity tolerance compared to that of the parental species. I also found that F. heteroclitus upregulated candidate hypersaline saltwater tolerance genes (cftr, claudin-10c and claudin-10f) to a greater extent than the two less tolerant groups, suggesting that increased tolerance in F. heteroclitus is associated with their unique ability to upregulate these genes
A gender-based analysis of the Good Lives Model’s primary goods : exploring women’s reintegrative experiences
Get PDF128 leaves ; 29 cmIncludes abstract and appendices.Includes bibliographical references (leaves 107-117).Given our justice system’s use of services designed specifically for men, I consider the appropriateness of an alternative model: The Good Lives Model of Offender Rehabilitation (GLM). Specifically, the gender-neutrality of its theoretical assumptions about reintegration. I explore if the GLM is suited to address the gendered nature of women’s reintegrative experiences, how relevant the GLM’s primary goods are to women’s efforts to reintegrate, and how the women’s experiences seeking these goods are gendered. This qualitative work involves open-ended interviews with previously incarcerated women who have lived in a transition house. Their stories were analyzed using a feminist criminological perspective. Findings suggest the GLM’s strengths-based approach and primary goods are relevant in these women’s lives. The goods are, however, only germane because the women have surpassed the difficult process of achieving life’s basic necessities. Without the transition house, the women would likely not be achieving success to the same degree
Pyrite chemistry and S isotope systematics associated with paragenesis of epithermal-style gold mineralization in the Eastern Cobequid Highlands, Nova Scotia, Canada
Get PDF1 online resource (ix, 86 pages) : illustrations (some colour), colour mapsIncludes abstract and appendix.Includes bibliographical references (pages 83-85).Within the northeastern Cobequid Highlands (CH), Nova Scotia, Canada recent bedrock mapping and bulk rock geochemistry have identified a potential epithermal Au system. The Warwick Mountain area shows the most potential for Au mineralization with two zones of intensely silicified and sulphidized basalt identified. Assays show anomalous As, Sb, Cd, W, Hg, with Au concentrations up to ~660 ppb.
Trace element chemistry and S isotope systematics of sulphide minerals are used to track deposit evolution and epithermal processes at a variety of scales, and develops exploration criteria using these data.
The host rock setting, enrichments in bulk rock Au, As, Sb, and Hg, and sulphide mineralogy are consistent with a low sulphidation epithermal Au style of mineralization. The bulk S (as mainly pyrite) correlates to bulk δ34SVCDT, possibly as a function of sulphate content enriched during sample weathering in core. The As content of pyrite correlates weakly to in-situ δ34SVCDT (by SIMS) in pyrite with As-rich zones often showing high δ34SVCDT, suggesting that 34S enrichment and As enrichment were coupled. Bulk δ34SVCDT correlates to in-situ δ34SVCDTbut bulk δ34SVCDT values are consistently higher by several ‰, suggesting partial oxidation of sulphides to sulphates and preferential loss of 32S in core during long-term storage (degassing, removal by rain water?). Pyrite grains with rare, late overgrowths showing very high δ34SVCDT values are attributed to sulphide derived from the reduction of seawater sulphate. There are systematic variations in As and δ34SVCDT in surface samples and a few core samples. The biggest variation between core and rim δ34SVCDT to more negative values occurs at the Nuttby Mountain occurrence, where late enrichment in Au, Ag, As, and Sb occurs in the rims of pyrite grains. Similar rim enrichment in Au was observed in some pyrite from drill core
The influences of health on labour market outcomes in Canada : analyses from the 2014 Canadian Community Health Survey
Get PDF1 online resource (41 p.)Includes abstract and appendix.Includes bibliographical references (p. 38-40).This thesis addresses the effects of seventeen chronic health conditions as defined by the 2014 Canadian Community Health Survey on labour market outcomes as measured by their labour force status: employed full-time, employed part-time, and not working. The estimation employed a multinomial logistic regression, which was then used to estimate the marginal effects of each health condition, as well in simulations that predicted probabilities of each employment outcome in the presence and absence of each condition. Further probabilities were estimated to differentiate the effects of major health conditions among demographic variables and levels of educations. Findings include that women are relatively more likely than men to exit full-time employment after the onset of a health condition; additionally, those who are younger and have higher levels of education are also more likely to maintain a full-time employment status relative to individuals who are older or less educated, and there are no differences in the impact of health conditions between immigrants and the native-born
Environmental Factors Influence Plant Vascular System and Water Regulation
Get PDFPublished versionDevelopmental initiation of plant vascular tissue, including xylem and phloem, from the vascular cambium depends on environmental factors, such as temperature and precipitation. Proper formation of vascular tissue is critical for the transpiration stream, along with photosynthesis as a whole. While effects of individual environmental factors on the transpiration stream are well studied, interactive effects of multiple stress factors are underrepresented. As expected, climate change will result in plants experiencing multiple co-occurring environmental stress factors, which require further studies. Also, the effects of the main climate change components (carbon dioxide, temperature, and drought) on vascular cambium are not well understood. This review aims at synthesizing current knowledge regarding the effects of the main climate change components on the initiation and differentiation of vascular cambium, the transpiration stream, and photosynthesis. We predict that combined environmental factors will result in increased diameter and density of xylem vessels or tracheids in the absence of water stress. However, drought may decrease the density of xylem vessels or tracheids. All interactive combinations are expected to increase vascular cell wall thickness, and therefore increase carbon allocation to these tissues. A comprehensive study of the effects of multiple environmental factors on plant vascular tissue and water regulation should help us understand plant responses to climate change
Quasi-free neutron and proton knockout reactions from light nuclei in a wide neutron-to-proton asymmetry range
Get PDFPublished versionThe quasi-free scattering reactions 11C(p, 2p) and 10,11,12C(p, pn) have been studied in inverse kinematics at beam energies of 300–400 MeV/u at the R3B-LAND setup. The outgoing proton-proton and proton neutron pairs were detected in coincidence with the reaction fragments in kinematically complete measurements. The efficiency to detect these pairs has been obtained from GEANT4 simulations which were tested using the 12C(p, 2p) and 12C(p, pn) reactions. Experimental cross sections and momentum distributions have been obtained and compared to DWIA calculations based on eikonal theory. The new results reported here are combined with previously published cross sections for quasi-free scattering from oxygen and nitrogen isotopes and together they enable a systematic study of the reduction of single particle strength compared to predictions of the shell model over a wide neutron-to-proton asymmetry range. The combined reduction factors show a weak or no dependence on isospin asymmetry, in contrast to the strong dependency reported in nucleon-removal reactions induced by nuclear targets at lower energies. However, the reduction factors for (p, 2p) are found to be ’significantly smaller than for (p, pn) reactions for all investigated nuclei
The nuclear environment of the NLS1 Mrk 335: Obscuration of the X-ray line emission by a variable outflow
Get PDFPublished versionWe present XMM–Newton, NuSTAR, Swift, and Hubble Space Telescope observations of the Narrow-line Seyfert 1 galaxy Mrk 335 in a protracted low state in 2018 and 2019. The X-ray flux is at the lowest level so far observed, and the extremely low continuum flux reveals a host of soft X-ray emission lines from photoionized gas. The simultaneous UV flux drop suggests that the variability is intrinsic to the source, and we confirm this with broad-band X-ray spectroscopy. The dominance of the soft X-ray lines at low energies and distant reflection at high energies, is therefore due to the respective emission regions being located far enough from the X-ray source that they have not yet seen the flux drop. Between the two XMM–Newton spectra, taken 6 months apart, the emission line ratio in the O vii triplet changes drastically. We attribute this change to a drop in the ionization of intervening warm absorption, which means that the absorber must cover a large fraction of the line emitting region, and extend much further from the black hole than previously assumed. The HST spectrum, taken in 2018, shows that new absorption features have appeared on the blue wings of C iii*, Lyα, Nv, Siiv, and Civ, likely due to absorbing gas cooling in response to the low flux state
