McGill University

About: McGill University is a education organization based out in Montreal, Quebec, Canada. It is known for research contribution in the topics: Population & Context (language use). The organization has 72688 authors who have published 162565 publications receiving 6966523 citations. The organization is also known as: Royal institution of advanced learning & University of McGill College.

Variation in δ15N and δ13C trophic fractionation: Implications for aquatic food web studies

Abstract: Use of stable isotope techniques to quantify food web relationships requires a priori estimates of the enrichment or depletion in δ15N and δ13C values between prey and predator (known as trophic fractionation; hereafter Δδ15N and Δδ13C). We conducted a broad-scale analysis of Δδ15N and Δδ13C from aquatic systems, including three new field estimates. Carnivores had significantly higher Δδ15N values than herbivores. Furthermore, carnivores, invertebrates, and lab-derived estimates were significantly more variable than their counterparts ( f-test, p < 0.00001). Δδ13C was higher for carnivores than for herbivores (p = 0.001), while variances did not differ significantly. Excluding herbivores, the average Δδ15N and Δδ13C were 3.4‰ and 0.8‰, respectively. But even with unbiased fractionation estimates, there is variation in isotopic fractionation that contributes to error in quantitative isotope model outputs. We simulated the error variance in δ15N-based estimates of trophic position and two-source δ13C diet mixing models, explicitly considering the observed variation in Δδ15N and Δδ13C, along with the other potential error sources. The resultant error in trophic position and mixing model outputs was generally minor, provided that primary consumers were used as baseline indicators for estimating trophic position and that end member d13C values in dietary mixing models were sufficiently distinct.

Sensors and regulators of intracellular pH

Abstract: Protons dictate the charge and structure of macromolecules and are used as energy currency by eukaryotic cells. The unique function of individual organelles therefore depends on the establishment and stringent maintenance of a distinct pH. This, in turn, requires a means to sense the prevailing pH and to respond to deviations from the norm with effective mechanisms to transport, produce or consume proton equivalents. A dynamic, finely tuned balance between proton-extruding and proton-importing processes underlies pH homeostasis not only in the cytosol, but in other cellular compartments as well.

Les passions de l'ame: on obsessive and harmonious passion.

Abstract: Passion is defined as a strong inclination toward an activity that people like, that they find important, and in which they invest time and energy Two types of passion are proposed: obsessive and harmonious Obsessive passion (OP) refers to a controlled internalization of an activity in one's identity that creates an internal pressure to engage in the activity that the person likes Harmonious passion (HP) refers to an autonomous internalization that leads individuals to choose to engage in the activity that they like HP promotes healthy adaptation whereas OP thwarts it by causing negative affect and rigid persistence Results from four studies involving more than 900 participants from different populations supported the proposed conceptualization

Response diversity, ecosystem change, and resilience

Abstract: Biological diversity appears to enhance the resilience of desirable ecosystem states, which is required to secure the production of essential ecosystem services. The diversity of responses to environmental change among species contributing to the same ecosystem function, which we call response diversity, is critical to resilience. Response diversity is particularly important for ecosystem renewal and reorganization following change. Here we present examples of response diversity from both terrestrial and aquatic ecosystems and across temporal and spatial scales. Response diversity provides adaptive capacity in a world of complex systems, uncertainty, and human-dominated environments. We should pay special attention to response diversity when planning ecosystem management and restoration, since it may contribute considerably to the resilience of desired ecosystem states against disturbance, mismanagement, and degradation.

Planck 2013 results. I. Overview of products and scientific results

Abstract: The European Space Agency’s Planck satellite, dedicated to studying the early Universe and its subsequent evolution, was launched 14 May 2009 and has been scanning the microwave and submillimetre sky continuously since 12 August 2009. In March 2013, ESA and the Planck Collaboration released the initial cosmology products based on the first 15.5 months of Planck data, along with a set of scientific and technical papers and a web-based explanatory supplement. This paper gives an overview of the mission and its performance, the processing, analysis, and characteristics of the data, the scientific results, and the science data products and papers in the release. The science products include maps of the cosmic microwave background (CMB) and diffuse extragalactic foregrounds, a catalogue of compact Galactic and extragalactic sources, and a list of sources detected through the Sunyaev-Zeldovich effect. The likelihood code used to assess cosmological models against the Planck data and a lensing likelihood are described. Scientific results include robust support for the standard six-parameter ΛCDM model of cosmology and improved measurements of its parameters, including a highly significant deviation from scale invariance of the primordial power spectrum. The Planck values for these parameters and others derived from them are significantly different from those previously determined. Several large-scale anomalies in the temperature distribution of the CMB, first detected by WMAP, are confirmed with higher confidence. Planck sets new limits on the number and mass of neutrinos, and has measured gravitational lensing of CMB anisotropies at greater than 25σ. Planck finds no evidence for non-Gaussianity in the CMB. Planck’s results agree well with results from the measurements of baryon acoustic oscillations. Planck finds a lower Hubble constant than found in some more local measures. Some tension is also present between the amplitude of matter fluctuations (σ8) derived from CMB data and that derived from Sunyaev-Zeldovich data. The Planck and WMAP power spectra are offset from each other by an average level of about 2% around the first acoustic peak. Analysis of Planck polarization data is not yet mature, therefore polarization results are not released, although the robust detection of E-mode polarization around CMB hot and cold spots is shown graphically.