23 Works

Frequency of biologically-defined AD in relation to age, sex, APOEε4 and cognitive impairment in a prospective cohort study

Joseph Therriault, Tharick Pascoal, Andrea Benedet, Jaime Fernandez-Arias, Tina Wang, Gleb Berzgin, Min Su Kang, Firoza Lussier, Mira Chamoun, Melissa Savard, Cecile Tissot, Gassan Massarweh, Jean-Paul Soucy, Paolo Vitali, Paramita Saha-Chaudhuri, Serge Gauthier & Pedro Rosa-Neto
Objective: To assess the frequency of biologically-defined Alzheimer’s disease (AD) in relation to age, sex and APOEε4, as well as rates of discordance between clinically- and biologically defined AD. Methods: We assessed cognitively unimpaired (CU) elderly (n=166), amnestic MCI (n=77) and probable AD dementia (n=62) subjects who underwent evaluation by dementia specialists and neuropsychologists in addition to amyloid-PET with [18F]AZD4694 and tau-PET with [18F]MK6240. Individuals were grouped according to their AD biomarker profile. Positive predictive...

Adaptation and competition in deteriorating environments

Romana Limberger & Gregor Fussmann
Evolution might rescue populations from extinction in changing environments. Using experimental evolution with microalgae, we investigated if competition influences adaptation to an abiotic stressor, and vice versa, if adaptation to abiotic change influences competition. In a first set of experiments, we propagated monocultures of five species with and without increasing salt stress for ~180 generations. When assayed in monoculture, two of the five species showed signatures of adaptation, that is, lines with a history of...

The Paris Climate Agreement and future sea level rise from Antartica

Robert M. DeConto, David Pollard, Richard B. Alley, Isabella Velicogna, Edward Gasson, Natalya Gomez, Shaina Sadai, Alan Condron, Daniel M. Gilford, Erica L. Ashe, Robert E. Kopp, Dawei Li & Andrea Dutton

Introductory gestures before songbird vocal displays are shaped by learning and biological predispositions

Raghav Rajan, Shikha Kalra, Vishruta Yawatkar, Logan James & Jon Sakata
Numerous animal displays begin with introductory gestures. For example, lizards start their head-bobbing displays with introductory push-ups and many songbirds begin their vocal displays by repeating introductory notes (INs) before producing their learned song. Among songbirds, the acoustic structure and the number of INs produced before song vary considerably between individuals in a species. While similar variation in songs between individuals is a result of learning, whether variation in INs are also due to learning...

Food availability and long-term predation risk interactively affect antipredator response

Shotaro Shiratsuru, Yasmine Majchrzak, Michael Peers, Emily Studd, Allyson Menzies, Rachael Derbyshire, Murray Humphries, Charles Krebs, Dennis Murray & Stan Boutin
Food availability and temporal variation in predation risk are both important determinants of the magnitude of antipredator responses, but their effects have rarely been examined simultaneously, particularly in wild prey. Here, we determine how food availability and long-term predation risk affect antipredator responses to acute predation risk by monitoring the foraging response of free-ranging snowshoe hares (Lepus americanus) to an encounter with a Canada lynx Lynx canadensis) in Yukon, Canada, over 4 winters (from 2015-2016...

Data from: Shale-hosted biota from the Dismal Lakes Group in Arctic Canada supports an early Mesoproterozoic diversification of eukaryotes

Corentin C. Loron, Galen P. Halverson, Robert H. Rainbird, Tom Skulski, Elizabeth C. Turner & Emmanuelle J. Javaux
The Mesoproterozoic is an important era for the development of eukaryotic organisms in oceans. The earliest unambiguous eukaryotic microfossils are reported in late Paleoproterozoic shales from China and Australia. During the Mesoproterozoic, eukaryotes diversified in taxonomy, metabolism and ecology, with the advent of eukaryotic photosynthesis, osmotrophy, multicellularity, and predation. Despite these biological innovations, their fossil record is scarce before the late Mesoproterozoic. Here, we document an assemblage of organic-walled microfossils from the 1590-1270 Ma Dismal...

Data to Prior exposure to stress allows the maintenance of an ecosystem cycle following severe acidification

Sofia Van Moorsel, Justin Marleau, Andrew Gonzalez, Owen Petchey, Charles Bazerghi & Jorge Negrin Dastis
This freshwater mesocosm study was conducted in 19 out of 110 mesocosms at the Large Experimental Array of Ponds (LEAP) at the Gault Nature Reserve in Mont-St-Hilaire, QC, Canada (45°32' N, 73°08' W, 122 m a.s.l.) between May and October 2018 for a total of 147 days. On 24 May 2018, the mesocosms (1100L stock tanks, Rubbermaid, Huntersville, NC, USA) were filled with approximately 1000 liters of unfiltered lake water via a pipeline from oligotrophic...

Supplemental material: Astrocyte biomarkers in Alzheimer’s disease: a systematic review and meta-analysis

Bruna Bellaver, João Pedro Ferrari-Souza, Lucas Uglione Da Ros, Stephen F. Carter, Elena Rodriguez-Vieitez, Agneta Nordberg, Luc Pellerin, Pedro Rosa-Neto, Douglas Teixeira Leffa & Eduardo R. Zimmer
Objective: To perform a systematic review and meta-analysis to determine whether fluid and imaging astrocyte biomarkers are altered in Alzheimer's disease (AD). Methods: PubMed and Web of Science databases were searched for articles reporting fluid or imaging astrocyte biomarkers in AD. Pooled effect sizes were determined with mean differences (SMD) using the Hedge’s G method with random-effects to determine biomarker performance. Adapted questions from QUADAS-2 were applied for quality assessment. A protocol for this study...

On the Believable Benefits of Low Inflation

Christopher Ragan
This paper reviews the existing theoretical and empirical literature addressing the benefits of low inflation. The ultimate goal is to arrive at a set of benefits in which a monetary authority can have genuine confidence. I argue that the current state of economic research—both empirical and theoretical—provides little basis for believing in significant observable benefits of low inflation such as an increase in the growth rate of real GDP. Moreover, what observable benefits do exist...

Electronic Transactions as High-Frequency Indicators of Economic Activity

John W. Galbraith & Greg Tkacz
Since the advent of standard national accounts data over 60 years ago, economists have traditionally relied on monthly or quarterly data supplied by central statistical agencies for macroeconomic modelling and forecasting. However, technological advances of the past several years have resulted in new high-frequency data sources that could potentially provide more accurate and timely information on the current level of economic activity. In this paper we explore the usefulness of electronic transactions as real-time indicators...

Data from: Habitat disturbance alters color contrast and the detectability of cryptic and aposematic frogs

James Barnett, Brandon Varela, Ben Jennings, David Lesbarrères, Jonathan Pruitt & David Green
Animals use color both to conceal and signal their presence, with patterns that match the background, disrupt shape recognition, or highlight features important for communication. The forms that these color patterns take are responses to the visual systems that observe them and the environments within which they are viewed. Increasingly, however, these environments are being affected by human activity. We studied how pattern characteristics and habitat change may affect the detectability of three frog color...

Adaptation across geographic ranges is consistent with strong selection in marginal climates and legacies of range expansion

Megan Bontrager, Takuji Usui, Julie Lee-Yaw, Daniel Anstett, Haley Branch, Anna Hargreaves, Christopher Muir & Amy Angert
Every species experiences limits to its geographic distribution. Some evolutionary models predict that populations at range edges are less well-adapted to their local environments due to drift, expansion load, or swamping gene flow from the range interior. Alternatively, populations near range edges might be uniquely adapted to marginal environments. In this study, we use a database of transplant studies that quantify performance at broad geographic scales to test how local adaptation, site quality, and population...

Biodiversity-productivity relationships are key to nature-based climate solutions

Akira Mori, Laura Dee, Andrew Gonzalez, Haruka Ohashi, Jane Cowles, Alexandra Wright, Michel Loreau, Yann Hautier, Tim Newbold, Peter Reich, Tetsuya Matsui, Wataru Takeuchi, Kei-Ichi Okada, Rupert Seidl & Forest Isbell
The global impacts of biodiversity loss and climate change are interlinked but the feedbacks between them are rarely assessed. Areas with greater tree diversity tend to be more productive, providing a greater carbon sink, and biodiversity loss could reduce these natural C sinks. Here, we quantify how tree and shrub species richness could affect biomass production at biome, national and regional scales. We find that greenhouse gas mitigation could help maintain tree diversity and thereby...

Data from: Chemical defense and tonic immobility in early life stages of the Harlequin cabbage bug, Murgantia histrionica (Heteroptera: Pentatomidae)

Eric Guerra-Grenier, Rui Liu, John T. Arnason & Thomas N. Sherratt
Antipredation strategies are important for the survival and fitness of animals, especially in more vulnerable life stages. In insects, eggs and early juvenile stages are often either immobile or unable to rapidly flee and hide when facing predators. Understanding what alternative antipredation strategies they use, but also how those change over development time, is required to fully appreciate how species have adapted to biotic threats. Murgantia histrionica is a stink bug, conspicuously colored from egg...

Progressive neurochemical abnormalities in cognitive and motor subgroups of ALS: a prospective multicentre study

Daniel Ta, Abdullah Ishaque, Ojas Srivastava, Chris Hanstock, Peter Seres, Dean Eurich, Collin Luk, Hannah Briemberg, Richard Frayne, Angela Genge, Simon Graham, Lawrence Korngut, Lorne Zinman & Sanjay Kalra
Objective: To evaluate progressive cerebral degeneration in amyotrophic lateral sclerosis (ALS) by assessing alterations in N-acetylaspartate (NAA) ratios in the motor and prefrontal cortex within clinical subgroups of ALS. Methods: Seventy-six ALS patients and 59 healthy controls were enrolled a prospective, longitudinal, multicenter study in the Canadian ALS Neuroimaging Consortium (CALSNIC). Participants underwent serial clinical evaluations and MRS at baseline, 4 and 8 months using a harmonized protocol across 5 centers. NAA ratios were quantified...

Multiple cropping alone does not improve year-round food security among smallholders in rural India

Pinki Mondal, Ruth DeFries, Jessica Clark, Nicole Flowerhill, , Aurélie Harou, Shauna Downs & Jessica Fanzo
Achieving and maintaining food and nutrition security is an important Sustainable Development Goal (SDG), especially in countries with largely vulnerable population with high occurrence of hunger and malnutrition. By studying a small-scale agricultural system in India, we aim to understand the current state of dietary diversity and food insecurity among the farmer communities. The study landscape has witnessed a steady rise in multiple cropping along with irrigation over the last two decades. Whether this multiple...

Price-Level Targeting and Inflation Expectations: Experimental Evidence

Robert Amano, Engle-Warnick Jim & Malik Shukayev
In this paper, we use an economics decision-making experiment to test a key assumption underpinning the efficacy of price-level targeting relative to inflation targeting for business cycle stabilization and mitigating the effects of the zero lower bound on nominal interest rates. In particular, we attempt to infer whether experimental participants understand the stationary nature of the price level under price-level targeting by observing their inflation forecasting behaviour in a laboratory setting. This is an important...

Synchronized file of allele frequencies for: Using seasonal genomic changes to understand historical adaptation to new environments: parallel selection on stickleback in highly-variable estuaries

Alan Garcia-Elfring, Rowan Barrett, Andrew Hendry, Timothy Thurman, Eric Palkovacs, Ben Wasserman & Antoine Paccard
Parallel evolution is considered strong evidence for natural selection. However, few studies have investigated the process of parallel selection as it plays out in real time. The common approach is to study historical signatures of selection in populations already well adapted to different environments. Here, to document selection under natural conditions, we study six populations of threespine stickleback (Gasterosteus aculeatus) inhabiting bar-built estuaries that undergo seasonal cycles of environmental changes. Estuaries are periodically isolated from...

Data: the complex ecology of genitalia: gonopodium length and allometry in the Trinidadian guppy

José Jonathas P R De Lira
Male genitalia present an extraordinary pattern of rapid divergence in animals with internal fertilization, which is usually attributed to sexual selection. However, the effect of ecological factors on genitalia divergence could also be important, especially so in animals with non-retractable genitalia because of their stronger interaction with the surrounding environment in comparison to animals with retractable genitalia. Here we examine the potential of a pervasive ecological factor (predation) to influence the length and allometry of...

How Far Can Forecasting Models Forecast? Forecast Content Horizons for Some Important Macroeconomic Variables

John W. Galbraith & Greg Tkacz
For stationary transformations of variables, there exists a maximum horizon beyond which forecasts can provide no more information about the variable than is present in the unconditional mean. Meteorological forecasts, typically excepting only experimental or exploratory situations, are not reported beyond this horizon; by contrast, little generally accepted information about such maximum horizons is available for economic variables. The authors estimate such content horizons for a variety of economic variables, and compare these with the...

High tree diversity enhances light interception in tropical forests

Marina Melo Duarte, Caroline Isaac Ferreira Zuim, Taísi Bech Sorrini, Luís Eduardo Bernardini, Rafael De Andrade Moral, Joannes Guillemot, Catherine Potvin, Wagner Hugo Bonat, José Luiz Stape & Pedro Henrique Santin Brancalion
We used two forest plantation experiments, the Sardinilla site in Panama (containing monocultures, 2-, 3- and 5-species mixtures in the main plantation, established in 2001, and 6-, 9- and18-species mixtures in the high-diversity plantation, established in 2003), and the Anhembi site in Brazil (established in 2006, containing 20-, 58- and 114-species mixtures), to investigate the effects of forest tree richness on the amount and distribution (horizontal, vertical and temporal) of intercepted ligh (red:far-red ratio -...

Source pool diversity and proximity shape the compositional uniqueness of insular mammal assemblages worldwide

Katherine Hébert, Virginie Millien & Jean-Philippe Lessard
Islands have been the test bed of several theories in community ecology, biogeography, and evolutionary biology. Progress within these disciplines has given a more comprehensive and mechanistic understanding of the processes governing variation in species richness among islands. However, it remains unclear whether these same processes also explain variation in species and phylogenetic composition among islands. Integrating theory from ecology and biogeography, we infer the roles of dispersal, selection, and stochasticity on the composition of...

The cell adhesion molecule Sdk1 shapes assembly of a retinal circuit that detects localized edges

Pierre-Luc Rochon, Catherine Theriault, Aline Giselle Rangel Olguin & Arjun Krishnaswamy
Nearly 50 different mouse retinal ganglion cell (RGC) types sample the visual scene for distinct features. RGC feature selectivity arises from its synapses with a specific subset of amacrine (AC) and bipolar cell (BC) types, but how RGC dendrites arborize and collect input from these specific subsets remains poorly understood. Here we examine the hypothesis that RGCs employ molecular recognition systems to meet this challenge. By combining calcium imaging and type-specific histological stains we define...

Registration Year

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Affiliations

  • McGill University
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  • University of British Columbia
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  • Bank of Canada
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  • University of Alberta
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  • University of Zurich
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  • University of Toronto
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  • Laurentian University
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  • University of Massachusetts Amherst
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  • University of Liège
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  • Brunel University London
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