Saint Mary's University

About: Saint Mary's University is a education organization based out in Halifax, Nova Scotia, Canada. It is known for research contribution in the topics: Population & Stars. The organization has 1931 authors who have published 4993 publications receiving 143226 citations.

The PL calibration for Milky Way Cepheids and its implications for the distance scale

Abstract: The rationale behind recent calibrations of the Cepheid PL relation using the Wesenheit formulation is reviewed and reanalyzed, and it is shown that recent conclusions regarding a possible change in slope of the PL relation for short-period and long-period Cepheids are tied to a pathological distribution of HST calibrators within the instability strip. A recalibration of the period-luminosity relation is obtained using Galactic Cepheids in open clusters and groups, the resulting relationship, described by log L/L ⊙=2.415(±0.035)+1.148(±0.044)log P, exhibiting only the moderate scatter expected from color spread within the instability strip. The relationship is confirmed by Cepheids with HST parallaxes, although without the need for Lutz-Kelker corrections, and in general by Cepheids with revised Hipparcos parallaxes, albeit with concerns about the cited precisions of the latter. A Wesenheit formulation of W V =−2.259(±0.083)−4.185(±0.103)log P for Galactic Cepheids is tested successfully using Cepheids in the inner regions of the galaxy NGC 4258, confirming the independent geometrical distance established for the galaxy from OH masers. Differences between the extinction properties of interstellar and extragalactic dust may yet play an important role in the further calibration of the Cepheid PL relation and its application to the extragalactic distance scale.

The chemical bond in external electric fields: Energies, geometries, and vibrational Stark shifts of diatomic molecules

Abstract: It is shown that the response of molecular properties of diatomics such as the total energy, the bond length, and the vibrational Stark shift to an external homogenous electric field (EF) can be predicted from field-free observable properties such as the equilibrium bond length, the bond dissociation energy, the polarizability and dipole moment functions, and the vibrational frequency. Delley [J. Mol. Struct.: THEOCHEM 434, 229 (1998)] suggested to approximate the potential energy surface under an EF by a Morse function augmented with a EF term proportional to the internuclear separation. In this work, this term is replaced by the expression of the field-induced energy change which yields a field-perturbed Morse potential that tends to a constant asymptotic limit when the EF term itself become proportional to the sum of the polarizabilities of the separated atoms. The model is validated by comparison with direct calculations on nine diatomics, five homo-nuclear (H2 ,N 2 ,O 2 ,F 2, and Cl2) and four hetero-nuclear (HF, HCl, CO, and NO), covering a range and combinations of dipole moments and polarizabilities. Calculations were conducted at the quadratic configuration interaction with single and double excitations (QCISD) and density functional theory (DFT)-B3LYP levels of theory using the 6-311++G(3df,2pd) basis set. All results agree closely at the two levels of theory except for the Stark effect of NO which is not correctly predicted by QCISD calculations as further calculations, including at the coupled cluster with single and double excitation (CCSD) level of theory, demonstrate. © 2013 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License. [http://dx.doi.org/10.1063/1.4820487]

Late Cretaceous and Cenozoic fossil dinoflagellates and other palynomorphs from the Scotian Margin, offshore eastern Canada

Abstract: Synopsis Palynomorphs, especially dinoflagellate cysts (dinocysts), have been at the forefront of research carried out on Mesozoic‐Cenozoic sediments on the Scotian Margin over the last 30–40 years: this research has been driven by the need to develop a stratigraphical framework to better understand the region's petroleum systems. To support the compilation of a detailed event strati‐graphical scheme for the Late Cretaceous to Cenozoic of the margin, emphasising dinocysts but with information from other fossil groups and non‐biostratigraphical data, there is a need to formalise the dinocyst taxonomy. In this paper, we fulfill this need by illustratingand, where appropriate, describing and discussing taxa used in our event biostratigraphical scheme. The following taxa (dinocysts except where indicated) are new: Areoligeracircumsenonensis,Axiodinium,Axiodiniumprearticulatum, Cordosphaeridium delimurum, Glaphyrocysta extensa, Hafniasphaera delicata, Impletosphaeridium capitatum, Mendicodinium robustum (valid...

Caught in a bad romance: perfectionism, conflict, and depression in romantic relationships.

Abstract: According to the social disconnection model, perfectionistic concerns (ie, harsh self-scrutiny, extreme concern over mistakes and others' evaluations, and excessive reactions to perceived failures) confer vulnerability to depressive symptoms indirectly through interpersonal problems This study tested the social disconnection model in 226 heterosexual romantic dyads using a mixed longitudinal and experience sampling design Perfectionistic concerns were measured using three partner-specific self-report questionnaires Conflict was measured as a dyadic variable, incorporating reports from both partners Depressive symptoms were measured using a self-report questionnaire Perfectionistic concerns and depressive symptoms were measured at Day 1 and Day 28 Aggregated dyadic conflict was measured with daily online questionnaires from Days 2 to 15 Data were analyzed using structural equation modeling There were four primary findings: (a) Dyadic conflict mediated the link between perfectionistic concerns and depressive symptoms, even when controlling for baseline depressive symptoms; (b) depressive symptoms were both an antecedent and a consequence of dyadic conflict; (c) perfectionistic concerns incrementally predicted dyadic conflict and depressive symptoms beyond neuroticism (ie, a tendency to experience negative emotions) and other-oriented perfectionism (ie, rigidly demanding perfection from one's partner); and (d) the relationships among variables did not differ based on gender As the most rigorous test of the social disconnection model to date, this study provides strong support for this emerging model Results also clarify the characterological and the interpersonal context within which depressive symptoms are likely to occur

Institutional investment horizon and investment–cash flow sensitivity

Abstract: This paper examines the relevance of institutional investors’ investment horizon, as reflected in the response of firm investment to internal cash flows. We argue that institutional investors with longer investment horizons have greater incentives and efficiencies to engage in effective monitoring. This improved monitoring mitigates asymmetric information and agency problems, and in turn reduces the wedge between the costs of internal and external funds. As a result, the sensitivity of firms’ investment outlays to internal cash flows decreases in the presence of institutional investors with long-term investment horizons. Using a sample of 8402 US firms over the period 1981–2008, we provide empirical evidence consistent with these arguments.