Time filter

Source Type

Squamish, Canada

Becker R.H.,University of California at Davis | Becker R.H.,Lawrence Livermore National Laboratory | Helfand D.J.,Columbia University | Helfand D.J.,Quest University | And 2 more authors.
Astronomical Journal | Year: 2010

Using three epochs of Very Large Array observations of the Galactic plane in the first quadrant taken 15 years apart, we have conducted a search for a population of variable Galactic radio emitters in the flux density range 1-100mJy at 6cm. We find 39 variable sources in a total survey area of 23.2deg2. Correcting for various selection effects and for the extragalactic variable population of active galactic nuclei, we conclude there are 1.6deg-2 Galactic sources which vary by more than 50% on a time scale of years (or shorter). We show that these sources are much more highly variable than extragalactic objects; more than 50% show variability by a factor >2 compared to <10% for extragalactic objects in the same flux density range. We also show that the fraction of variable sources increases toward the Galactic center (another indication that this is a Galactic population), and that the spectral indices of many of these sources are flat or inverted. A small number of the variables are coincident with mid-IR sources and two are coincident with X-ray emitters, but most have no known counterparts at other wavelengths. Intriguingly, one lies at the center of a supernova remnant, while another appears to be a very compact planetary nebula; several are likely to represent activity associated with star formation regions. We discuss the possible source classes which could contribute to the variable cohort and follow-up observations which could clarify the nature of these sources. © 2010 The American Astronomical Society. All rights reserved. Source

Sanderson D.,University of Victoria | Picketts I.M.,Quest University | Dery S.J.,University of Northern British Columbia | Fell B.,University of Northern British Columbia | And 3 more authors.
Canadian Geographer | Year: 2015

Insights from both western science and traditional knowledge were applied to identify, and begin to address, climate change and water impacts at Stellat'en First Nation, British Columbia, Canada. Qualitative data from interviews and surveys of Stellat'en community members were compiled and compared with air temperature, precipitation, and hydrometric data from meteorological stations and proximal rivers. Community Elders noted changes to river water levels and shifts in fish populations. The quantitative data revealed a 2.3 °C rise in air temperature, 5 percent increase in precipitation, and 10 percent decline in snowfall over a 40-year period. Results from these analyses were reported in two knowledge intersection workshops at Stellat'en First Nation, and information sharing took place to: facilitate discussion and awareness between traditional and western knowledge holders, gain insights on the community's views of climate change and water, and identify strategies for action. Recommendations formulated and implemented by Stellat'en First Nation include improved policies, and community and individual actions. © 2015 Canadian Association of Geographers / L' Association canadienne des géographes. Source

Barazandeh M.,University of Alberta | Barazandeh M.,Bamfield Marine Sciences Center | Davis C.S.,University of Alberta | Neufeld C.J.,University of Alberta | And 5 more authors.
Proceedings of the Royal Society B: Biological Sciences | Year: 2013

Most free-living barnacles are hermaphroditic, and eggs are presumed to be fertilized either by pseudo-copulation or self-fertilization. Although the common northeast Pacific intertidal gooseneck barnacle, Pollicipes polymerus, is believed only to cross-fertilize, some isolated individuals well outside penis range nonetheless bear fertilized eggs. They must therefore either self-fertilize or-contrary to all prior expectations about barnacle mating-obtain sperm from the water. To test these alternative hypotheses, we collected isolated individuals bearing egg masses, as well as isolated pairs where at least one parent carried egg masses. Using 16 single nucleotide polymorphism markers, we confirmed that a high percentage of eggs were fertilized with sperm captured from the water. Sperm capture occurred in 100 per cent of isolated individuals and, remarkably, even in 24 per cent of individuals that had an adjacent partner. Replicate subsamples of individual egg masses confirmed that eggs fertilized by captured sperm occurred throughout the egg mass. Sperm capture may therefore be a common supplement to pseudo-copulation in this species. These observations (i) overturn over a century of beliefs about what barnacles can (or cannot) do in terms of sperm transfer, (ii) raise doubts about prior claims of selffertilization in barnacles, (iii) raise interesting questions about the capacity for sperm capture in other species (particularly those with short penises), and (iv) show, we believe for the first time, that spermcast mating can occur in an aquatic arthropod. © 2013 The Author(s) Published by the Royal Society. All rights reserved. Source

Lewis T.R.,Westfield | Griffin R.K.,Brook Lea | Grant P.B.C.,4901 Cherry Tree Bend | Figueroa A.,University of New Orleans | And 4 more authors.
Phyllomedusa | Year: 2013

Physical measurements, abundance, and ecological observations were recorded for Sibon annulatus, S. argus, S. longifrenis, and S. nebulatus at two Neotropical habitats: a lowland swamp forest in Costa Rica and a montane cloud forest in Panama. Fourty-four and 58 adult snakes were recorded from Costa Rica and Panama, respectively. Differences in morphology and body condition showed minimal significant differences among species from both geographical locations. Observations of feeding, reproduction, abundance, distribution, and a new size record for S. annulatus are discussed. © 2013 Departamento de Ciências Biológicas - ESALQ - USP. Source

Gould L.,University of Victoria | Gabriel D.N.,Quest University
African Journal of Ecology | Year: 2015

Lemur catta's ability to consume a wide variety of plant foods is a key to this species' survival in a time of ecological crisis across its geographic range. We examined seasonal diet variability of L. catta groups inhabiting two rocky outcrop fragments in south-central Madagascar: Anja Reserve and Tsaranoro Valley forest. Leaves and fruit of Melia azedarach were a keystone resource for Anja lemurs in wet and dry seasons. At Tsaranoro, L. catta relied on M. azedarach and Ficus spp. in dry season, but during the wet season, neither was a dominant food resource. Top food species at both sites differed markedly from those consumed by L. catta in other habitats. At Tsaranoro, a greater proportion of lemurs engaged in feeding during the dry season compared with wet season. We attribute this to resource scarcity during dry season, when greater feeding effort is needed to maintain energy requirements. Because M. azedarach is ubiquitous throughout Anja Reserve, producing fruit and leaves year-round, Anja lemurs can meet energy requirements with little seasonal adjustment in feeding activity. L. catta's IUCN status has been upgraded to Endangered, thus, greater insight into its diet flexibility and ability to survive on introduced plant species, can inform conservation plans in remaining wild habitats and ex situ programs. © 2014 John Wiley & Sons Ltd. Source

Discover hidden collaborations