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.

Guidelines for time use data collection

Abstract: Growing and widespread interest in time begs the need for time use data collection and reporting standards. Initial guidance for comparative work was provided by the Multinational Time Use Project. However, changing technologies, methodologies, and divergent data needs have given rise to the need for updated guidance. This paper, prepared with input from members of the International Association for Time Use Research, examines the history and applications of time use data, identifies and evaluates methodological options for time use studies, recommends options facilitating cross-national and cross-temporal comparability and identifies methodological challenges facing time use researchers. The study concludes that alternative collection methods appear to make little difference in the resulting activity and time use estimates at customary levels of reporting.

New Social Movements in Latin America: The Dynamics of Class and Identity

Abstract: The insurrection of indigenous peasants in Chiapas on the first of January in 1994 has had a profound impact. Not only did it put an end to the ruling class’s — and party’s — illusion of social peace and stability, and brought on centre-stage the long and hard struggles of indigenous peoples in Mexico and elsewhere, but it had a significant impact on what we could term the sociology of social movements — the way in which movements of resistance and social change are conceived. In the immediate context, the uprising seriously undermined and tarnished the glow that surrounded the government’s neoliberal policies of structural adjustment which just a month earlier had been lauded by president Clinton at a summit of Latin American heads of state as a model for other governments in the region to follow. In the same context, it raised serious questions about the feasibility of armed struggle, a tactic that had all but been abandoned by the Left as a result of the repeated failures and the destruction of the many organizations that had taken up arms in the 1960s and 1970s.

Three-dimensional convection simulations of the outer layers of the Sun using realistic physics

Abstract: This paper describes a series of 3D simulations of shallow inefficient convection in the outer layers of the Sun. The computational domain is a closed box containing the convection-radiation transition layer, located at the top of the solar convection zone. The most salient features of the simulations are that: i)The position of the lower boundary can have a major effect on the characteristics of solar surface convection (thermal structure, kinetic energy and turbulent pressure). ii)The width of the box has only a minor effect on the thermal structure, but a more significant effect on the dynamics (rms velocities). iii)Between the surface and a depth of 1 Mm, even though the density and pressure increase by an order of magnitude, the vertical correlation length of vertical velocity is always close to 600 km. iv) In this region the vertical velocity cannot be scaled by the pressure or the density scale height. This casts doubt on the applicability of the mixing length theory, not only in the superadiabatic layer, but also in the adjacent underlying layers. v) The final statistically steady state is not strictly dependent on the initial atmospheric stratification.

Secular evolution of viscous and self-gravitating circumstellar discs

Abstract: We add the effect of turbulent viscosity via the α-prescription to models of the self-consistent formation and evolution of protostellar discs Our models are non-axisymmetric and are carried out using the thin-disc approximation Self-gravity plays an important role in the early evolution of a disc, and the later evolution is determined by the relative importance of gravitational and viscous torques In the absence of viscous torques, a protostellar disc evolves into a self-regulated state with the Toomre parameter Q ∼ 15 - 20, non-axisymmetric structure diminishing with time and maximum disc-to-star mass ratio ξ = 014 We estimate an effective viscosity parameter α eff associated with gravitational torques at the inner boundary of our simulation to be in the range 10 -4 -10 -3 during the late evolution The addition of viscous torques with a low value a = 10 -4 has little effect on the evolution, structure and accretion properties of the disc, and the self-regulated state is largely preserved A sequence of increasing values of a results in the discs becoming more axisymmetric in structure, being more gravitationally stable, having greater accretion rates, larger sizes, shorter lifetimes and lower disc-to-star mass ratios For a = 10 -2 , the model is viscous-dominated, and the self-regulated state largely disappears by late times The axisymmetry and low surface density of this model may contrast with observations and pose problems for planet formation models The use of α = 01 leads to very high disc accretion rates and rapid (within 2 Myr) depletion of the disc, and seems even less viable observationally Furthermore, only the non-viscous-dominated models with low values of a = 10 -4 -10 -3 can account for an early phase of quiescent low accretion rate M ∼ 10 -8 M ⊙ yr -1 (interspersed with accretion bursts) that can explain the recently observed Very Low luminosity Objects (VeLLOs) We also find that a modest increase in disc temperature caused by a stiffer barotropic equation of state (y = 167) has little effect on the disc accretion properties averaged over many disc orbital periods (∼10 4 yr), but can substantially influence the instantaneous mass accretion rates, particularly in the early embedded phase of disc evolution