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.

Thermal Conductivity of Standard Sands II. Saturated Conditions

Abstract: A non-stationary thermal probe technique was used to measure the thermal conductivity of three saturated standard sands (Ottawa sand C-109, Ottawa sand C-190, and Toyoura sand) in a range of soil porosities (n) from 0.32 to 0.42, and temperatures (T) from 25 °C to 70 °C. The sand thermal conductivities at full saturation (λ sat) increased with decreasing n (increasing compaction, 1 − n). In addition, a declining λ sat(T) n=const trend was observed. The peak λ sat values and highest decreasing rate of λ sat with T were observed at the heaviest compaction and lowest tested T. This trend gradually diminished with increasing T and expanding volume of water (larger n) due to the markedly lower ability of water to conduct heat than quartz. A series-parallel model, containing three parallel paths of heat flow (through continuous solids, continuous fluid, and solids plus fluid in series), was successfully applied to predicted λ dry and λ sat data. The model by de Vries, with new fitted grain shape values, also closely followed measured λ sat data. The corresponding square root of the relative mean squared errors varied from 2.9 % to 3.4 % for C-109, from 1.9 % to 3.0 % for C-190, and from 2.3 % to 2.4 % for Toyoura sand. The use of a weighted geometric mean model also provided good λ sat estimates with errors ranging from 3.1 % to 3.5 % for C-109 and C-190 and 8.3 % for Toyoura sand. This paper also discusses a successful attempt to model λ sat as a product of thermal conductivity of the solid fraction (quartz plus other minerals) and a thermal conductance factor of water.

MaGICC baryon cycle: the enrichment history of simulated disc galaxies

Abstract: Using cosmological galaxy formation simulations from the MaGICC (Making Galaxies in a Cosmological Context) project, spanning stellar mass from ∼107 to 3 × 1010 M⊙, we trace the baryonic cycle of infalling gas from the virial radius through to its eventual participation in the star formation process. An emphasis is placed upon the temporal history of chemical enrichment during its passage through the corona and circumgalactic medium. We derive the distributions of time between gas crossing the virial radius and being accreted to the star-forming region (which allows for mixing within the corona), as well as the time between gas being accreted to the star-forming region and then ultimately forming stars (which allows for mixing within the disc). Significant numbers of stars are formed from gas that cycles back through the hot halo after first accreting to the star-forming region. Gas entering high-mass galaxies is pre-enriched in low-mass proto-galaxies prior to entering the virial radius of the central progenitor, with only small amounts of primordial gas accreted, even at high redshift (z ∼ 5). After entering the virial radius, significant further enrichment occurs prior to the accretion of the gas to the star-forming region, with gas that is feeding the star-forming region surpassing 0.1 Z⊙ by z = 0. Mixing with halo gas, itself enriched via galactic fountains, is thus crucial in determining the metallicity at which gas is accreted to the disc. The lowest mass simulated galaxy (Mvir ∼ 2 × 1010 M⊙, with M⋆ ∼ 107 M⊙), by contrast, accretes primordial gas through the virial radius and on to the disc, throughout its history. Much like the case for classical analytical solutions to the so-called ‘G-dwarf problem’, overproduction of low-metallicity stars is ameliorated by the interplay between the time of accretion on to the disc and the subsequent involvement in star formation – i.e. due to the inefficiency of star formation. Finally, gas outflow/metal removal rates from star-forming regions as a function of galactic mass are presented.

Social Identities in a Globalized World: Challenges and Opportunities for Collective Action

Abstract: Globalization—the increasing interconnectedness of societies, economies, and cultures—is a defining feature of contemporary social life. Paradoxically, it underlies both the dynamics of global cris...

Signals of Trustworthiness in E-Commerce: Consumer Understanding of Third-Party Assurance Seals

Abstract: Signaling theory provides the framework to address three main research questions: (1) How accurately do consumers notice and recollect TPA seals on retail Web sites? (2) How familiar are consumers with major TPA seals? and (3) How accurately do consumers understand the assurances represented by the TPA seals? Results of this study of three major TPA seals (TRUSTe, BBBOnLine Reliability, and VeriSign) reveal that subjects have poor recall of TPA seals viewed on a Web site, have limited familiarity with TPA programs, and have incomplete and largely inaccurate perceptions of the assurances that TPA seals represent These results suggest that TPA seals may not fulfill their potential to influence consumer trust in e-commerce because the signals are not noticed on merchant Web sites or adequately understood by consumers

The Differential Rotation of κ1 Ceti as Observed by MOST

Abstract: We first reported evidence for differential rotation of ?1 Ceti in Paper I. In this paper we demonstrate that the differential rotation pattern closely matches that for the Sun. This result is based on additional MOST observations in 2004 and 2005, as well as those from 2003. Using StarSpotz, a program developed specifically to analyze MOST photometry, we have solved for k, the differential rotation coefficient, and Peq, the equatorial rotation period using the light curves from all three years. The absolute range in spot latitudes is 10?-75? and k = 0.090, less than the solar value but consistent with the younger age of the star; k is also well constrained by the independent spectroscopic estimate of v sin i. We demonstrate independently that the pattern of differential rotation with latitude is indeed solar. Details are given of the parallel tempering formalism used in finding the most robust solution, which gives Peq = 8.77 days, smaller than that usually adopted, implying an age <750 My. Our values of Peq and k can explain the range of rotation periods others have found by spots or activity at a variety of latitudes. Historically, Ca II activity seems to occur consistently between latitudes 50? and 60?, which might indicate a permanent magnetic feature. Knowledge of k and Peq is key to understanding the dynamo mechanism and rotation structure in the convective zone, as well assessing age for solar-type stars. We recently published values of k and Peq for Eri based on MOST photometry and expect to analyze MOST light curves for several more spotted, solar-type stars.