University of Victoria

About: University of Victoria is a education organization based out in Victoria, British Columbia, Canada. It is known for research contribution in the topics: Population & Galaxy. The organization has 14994 authors who have published 41051 publications receiving 1447972 citations. The organization is also known as: Victoria College.

A Planetary Companion to γ Cephei A

Abstract: We report on the detection of a planetary companion in orbit around the primary star of the binary system γ Cephei. High-precision radial velocity measurements using four independent data sets spanning the time interval 1981-2002 reveal long-lived residual radial velocity variations superposed on the binary orbit that are coherent in phase and amplitude with a period or 2.48 yr (906 days) and a semiamplitude of 27.5 m s-1. We performed a careful analysis of our Ca II H and K S-index measurements, spectral line bisectors, and Hipparcos photometry. We found no significant variations in these quantities with the 906 day period. We also reanalyzed the Ca II λ8662 measurements of Walker et al., which showed possible periodic variations with the "planet" period when first published. This analysis shows that periodic Ca II equivalent width variations were only present during 1986.5-1992 and absent during 1981-1986.5. Furthermore, a refined period for the Ca II λ8662 variations is 2.14 yr, significantly less than the residual radial velocity period. The most likely explanation of the residual radial velocity variations is a planetary-mass companion with M sin i = 1.7MJ and an orbital semimajor axis of a2 = 2.13 AU. This supports the planet hypothesis for the residual radial velocity variations for γ Cep first suggested by Walker et al. With an estimated binary orbital period of 57 yr, γ Cep is the shortest period binary system in which an extrasolar planet has been found. This system may provide insights into the relationship between planetary and binary star formation.

Knowledge, Learning and the Evolution of Conservation Practice for Social-Ecological System Resilience

Abstract: There are two broadly conceptualized ways in which conservation knowledge may evolve: the depletion crisis model and the ecological understanding model. The first one argues that developing conservation thought and practice depends on learning that resources are depletable. Such learning typically follows a resource crisis. The second mechanism emphasizes the development of conservation practices following the incremental elaboration of environmental knowledge by a group of people. These mechanisms may work together. Following a perturbation, a society can self-organize, learn and adapt. The self-organizing process, facilitated by knowledge development and learning, has the potential to increase the resilience (capability to absorb disturbance and reorganize while undergoing change) of resource use systems. Hence, conservation knowledge can develop through a combination of long-term ecological understanding and learning from crises and mistakes. It has survival value, as it increases the resilience of integrated social--ecological systems to deal with change in ways that continue to sustain both peoples and their environments.

Built Environment Influences on Healthy Transportation Choices: Bicycling versus Driving

Abstract: A growing body of evidence links the built environment to physical activity levels, health outcomes, and transportation behaviors. However, little of this research has focused on cycling, a sustainable transportation option with great potential for growth in North America. This study examines associations between decisions to bicycle (versus drive) and the built environment, with explicit consideration of three different spatial zones that may be relevant in travel behavior: trip origins, trip destinations, and along the route between. We analyzed 3,280 utilitarian bicycle and car trips in Metro Vancouver, Canada made by 1,902 adults, including both current and potential cyclists. Objective measures were developed for built environment characteristics related to the physical environment, land use patterns, the road network, and bicycle-specific facilities. Multilevel logistic regression was used to model the likelihood that a trip was made by bicycle, adjusting for trip distance and personal demographics. Separate models were constructed for each spatial zone, and a global model examined the relative influence of the three zones. In total, 31% (1,023 out of 3,280) of trips were made by bicycle. Increased odds of bicycling were associated with less hilliness; higher intersection density; less highways and arterials; presence of bicycle signage, traffic calming, and cyclist-activated traffic lights; more neighborhood commercial, educational, and industrial land uses; greater land use mix; and higher population density. Different factors were important within each spatial zone. Overall, the characteristics of routes were more influential than origin or destination characteristics. These findings indicate that the built environment has a significant influence on healthy travel decisions, and spatial context is important. Future research should explicitly consider relevant spatial zones when investigating the relationship between physical activity and urban form.

The Gemini Planet Imager Exoplanet Survey: Giant Planet and Brown Dwarf Demographics from 10 to 100 au

Abstract: Author(s): Nielsen, EL; De Rosa, RJ; Macintosh, B; Wang, JJ; Ruffio, JB; Chiang, E; Marley, MS; Saumon, D; Savransky, D; Mark Ammons, S; Bailey, VP; Barman, T; Blain, C; Bulger, J; Burrows, A; Chilcote, J; Cotten, T; Czekala, I; Doyon, R; Duchene, G; Esposito, TM; Fabrycky, D; Fitzgerald, MP; Follette, KB; Fortney, JJ; Gerard, BL; Goodsell, SJ; Graham, JR; Greenbaum, AZ; Hibon, P; Hinkley, S; Hirsch, LA; Hom, J; Hung, LW; Ilene Dawson, R; Ingraham, P; Kalas, P; Konopacky, Q; Larkin, JE; Lee, EJ; Lin, JW; Maire, J; Marchis, F; Marois, C; Metchev, S; Millar-Blanchaer, MA; Morzinski, KM; Oppenheimer, R; Palmer, D; Patience, J; Perrin, M; Poyneer, L; Pueyo, L; Rafikov, RR; Rajan, A; Rameau, J; Rantakyro, FT; Ren, B; Schneider, AC; Sivaramakrishnan, A; Song, I; Soummer, R; Tallis, M; Thomas, S; Ward-Duong, K; Wolff, S | Abstract: We present a statistical analysis of the first 300 stars observed by the Gemini Planet Imager Exoplanet Survey. This subsample includes six detected planets and three brown dwarfs; from these detections and our contrast curves we infer the underlying distributions of substellar companions with respect to their mass, semimajor axis, and host stellar mass. We uncover a strong correlation between planet occurrence rate and host star mass, with stars M ∗ g1.5 M o more likely to host planets with masses between 2 and 13M Jup and semimajor axes of 3-100 au at 99.92% confidence. We fit a double power-law model in planet mass (m) and semimajor axis (a) for planet populations around high-mass stars (M ∗ g1.5 M o) of the form , finding α = -2.4 +0.8 and β = -2.0 +0.5, and an integrated occurrence rate of % between 5-13M Jup and 10-100 au. A significantly lower occurrence rate is obtained for brown dwarfs around all stars, with % of stars hosting a brown dwarf companion between 13-80M Jup and 10-100 au. Brown dwarfs also appear to be distributed differently in mass and semimajor axis compared to giant planets; whereas giant planets follow a bottom-heavy mass distribution and favor smaller semimajor axes, brown dwarfs exhibit just the opposite behaviors. Comparing to studies of short-period giant planets from the radial velocity method, our results are consistent with a peak in occurrence of giant planets between ∼1 and 10 au. We discuss how these trends, including the preference of giant planets for high-mass host stars, point to formation of giant planets by core/pebble accretion, and formation of brown dwarfs by gravitational instability.