The Functional Significance of Black-Pigmented Leaves: Photosynthesis, Photoprotection and Productivity in Ophiopogon planiscapus ‘Nigrescens’

Black pigmented leaves are common among horticultural cultivars, yet are extremely rare across natural plant populations. We hypothesised that black pigmentation would disadvantage a plant by reducing photosynthesis and therefore shoot productivity, but that this trait might also confer protective benefits by shielding chloroplasts against photo-oxidative stress. CO2 assimilation, chlorophyll a fluorescence, shoot biomass, and pigment concentrations were compared for near isogenic green- and black-leafed Ophiopogon planiscapus ‘Nigrescens’. The black leaves had lower maximum CO2 assimilation rates, higher light saturation points and higher quantum efficiencies of photosystem II (PSII) than green leaves. Under saturating light, PSII photochemistry was inactivated less and recovered more completely in the black leaves. In full sunlight, green plants branched more abundantly and accumulated shoot biomass quicker than the black plants; in the shade, productivities of the two morphs were comparable. The data indicate a light-screening, photoprotective role of foliar anthocyanins. However, limitations to photosynthetic carbon assimilation are relatively small, insufficient to explain the natural scarcity of black-leafed plants

From the Margins to the Center: Southern Women\u27s Activism, 1820-1970

In 1988, participants in the First Southern Conference on Women’s History lamented the neglect of southern women’s history. Despite the rich research possibilities suggested by Gerda Lerner’s 1967 biography of the Grimké sisters of South Carolina and her documentary history, Black Women in White America (1972), and by Anne Firor Scott’s The Southern Lady: From Pedestal to Politics, 1830-1930 (1970), only a small fraction of the new scholarship on women’s history dealt with the South.1 Women’s historians focused largely on women in the North, while southern historians examined race, but not gender, and African American historians generally ignored black women in their analyses

\u27Parallel Universe\u27 or \u27Proven Future\u27? The Language of Dependent Means t-Test Interpretations

Of the three kinds of two-mean comparisons which judge a test statistic against a critical value taken from a Student t-distribution, one – the repeated measures or dependent-means application – is distinctive because it is meant to assess the value of a parameter which is not part of the natural order. This absence forces a choice between two interpretations of a significant test result and the meaning of the test hypothesis. The parallel universe view advances a conditional, backward-looking conclusion. The more practical proven future interpretation is a non-conditional proposition about what will happen if an intervention is (now) applied to each population element. Proven future conclusions are subject to the corrupting influence of time-displacement, which include the effects of learning, development, and history. These two interpretations are explored, and a proposal for new conceptual categories and nomenclature is given to distinguish them, applicable to other repeated measures procedures derived from the general linear model including ANOVA

Systematic Analysis of 22 Microlensing Parallax Candidates

We attempt to identify all microlensing parallax events for which the parallax fit improves \Delta\chi^2 > 100 relative to a standard microlensing model. We outline a procedure to identify three types of discrete degeneracies (including a new one that we dub the ``ecliptic degeneracy'') and find many new degenerate solutions in 16 previously published and 6 unpublished events. Only four events have one unique solution and the other 18 events have a total of 44 solutions. Our sample includes three previously identified black-hole (BH) candidates. We consider the newly discovered degenerate solutions and determine the relative likelihood that each of these is a BH. We find the lens of event MACHO-99-BLG-22 is a strong BH candidate (78%), event MACHO-96-BLG-5 is a marginal BH candidate (37%), and MACHO-98-BLG-6 is a weak BH candidate (2.2%). The lens of event OGLE-2003-BLG-84 may be a Jupiter-mass free-floating planet candidate based on a weak 3 sigma detection of finite-source effects. We find that event MACHO-179-A is a brown dwarf candidate within ~100 pc of the Sun, mostly due to its very small projected Einstein radius, \tilde r_E = 0.23+-0.05 AU. As expected, these microlensing parallax events are biased toward lenses that are heavier and closer than average. These events were examined for xallarap (or binary-source motion), which can mimic parallax. We find that 23% of these events are strongly affected by xallarap.Comment: 69 Pages, 10 Figures, 24 Tables, Submitted to Ap

Variation in thermal sensitivity among coral genotypes, species, and habitats: Implications for improved restoration

Global climate change has rapidly altered marine systems, resulting in negative impacts on tropical reef-building corals around the globe. As the leading driver of coral bleaching, ocean warming disrupts the mutualistic relationship between reef-building corals and their algal symbionts (Symbiodinaceae) in a process known as coral bleaching. During periods of elevated sea temperatures corals expel their symbionts causing declines in metabolic and physiological function. Mass bleaching events deteriorate coral reefs, reducing the ecosystem services they provide including foundational habitat which host 32 of 34 recognized marine phyla of the ocean’s biodiversity, impacts on reef fisheries, physically protecting coasts from storms by reducing erosion, and elevates economic income of coastal communities. To reduce the impacts of warming, conservationists are attempting to protect and revitalize these systems by identifying resilient reefs. The goal is then to enhance coral abundance and preserve coral genetic variation with coral farming, and related restoration efforts. These activities are relatively new and identifying resilient corals and refining coral restoration techniques are only just beginning. Identifying how different coral species respond to restoration activities and their responses to temperature in general is critical in understanding coral persistence in the future. This dissertation examines the effect temperature has on coral survival, metabolism, and physiology from three conservation perspectives to enhance restoration methodologies in Caribbean and north Atlantic coral ecosystems. In Chapter 1, I identified a potential thermal refuge habitat in Bermuda by comparing thermal tolerance, optima, and sensitivities of four coral species from shallow and upper-mesophotic reef habitats. In Chapter 2, I used metabolic thermal performance curves (respiration and gross photosynthesis) to assess the effectiveness of stress-mediating interventions to alter thermal performance during heat stress, for use in coral farming. The results from this work highlight how variation in genotypes can influence metabolic and physiological responses (Acropora cervicornis) to thermal stress. In Chapter 3, I showed how genotypic variation (Orbicella annularis) and environmental interactions are necessary in planning and understanding the success of coral restoration across environmental gradients. Overall, investigating how corals respond to temperature stress and restoration methodologies are important in predicting the future persistence of corals and identifying successful procedures to enhance coral conservation.Doctor of Philosoph

Des bons pères aux experts : les élites catholiques et la modernisation du système scolaire au Québec, 1940-1964

Dans l'enseignement catholique de la province de Québec, à partir de 1940, l’augmentation du taux de fréquentation scolaire induit un mouvement de bureaucratisation. À cause de l'existence de trois structures juridico-administratives scolaires, la coordination et le financement deviennent les éléments clefs de cette rationalisation qui s'amorce au sein de l'Église catholique. L'orientation scolaire et professionnelle s'impose comme pratique scientifique de sélection des élèves de l'enseignement secondaire indépendant. Elle devient une expertise sur le système scolaire pour un nouveau groupe de réformistes et de professionnels. Une nouvelle élite catholique formée aux sciences de l'homme et de la société, porteuse d’un mouvement de renouveau catholique, s'impose tant dans les officines que sur la place publique. À travers l’œuvre de Wilfrid Éthier, p.s.s. et de ses élèves, Marcel Lauzon ptre et Arthur Tremblay, ce qui, au point de départ, fut un moyen d'apostolat et d'action sociale pour des religieux et des laïcs, se comprend comme le cadre de la modernisation par l'État du système scolaire du Québec pendant les années 1960

MeV-mass dark matter and primordial nucleosynthesis

The annihilation of new dark matter candidates with masses $m_X$ in the MeV range may account for the galactic positrons that are required to explain the 511 keV $\gamma$-ray flux from the galactic bulge. We study the impact of MeV-mass thermal relic particles on the primordial synthesis of $^2$H, $^4$He, and $^7$Li. If the new particles are in thermal equilibrium with neutrinos during the nucleosynthesis epoch they increase the helium mass fraction for m_X\alt 10 MeV and are thus disfavored. If they couple primarily to the electromagnetic plasma they can have the opposite effect of lowering both helium and deuterium. For $m_X=4$--10 MeV they can even improve the overall agreement between the predicted and observed $^2$H and $^4$He abundances.Comment: 11 pages, 10 figures, references and two appendices added, conclusions unchanged; accepted for publication in Phys.Rev.