York University

About: York University is a education organization based out in Toronto, Ontario, Canada. It is known for research contribution in the topics: Population & Poison control. The organization has 18899 authors who have published 43357 publications receiving 1568560 citations.

A deep ALMA image of the Hubble Ultra Deep Field

Abstract: European Research Council via the award of an Advanced Grant; EC [312725]; European Research Council via the award of a Consolidator Grant; UK Science and Technology Facilities Council; FWO Pegasus Marie Curie Fellowship; European Research Council through the Advanced Grant [321302, 669253, 670193]; JSPS KAKENHI [JP15K17604]; Chulalongkorn University's CUniverse (CUAASC); Royal Society

Entrepreneurship and economic growth: Evidence from emerging and developed countries

Abstract: This paper presents an extension to the economic growth model developed by Wong, Ho, and Autio (2005), to reflect differences in the economic effects of opportunity and necessity-based entrepreneurship in both emerging and developed countries. Data from 44 countries for the years 2004 and 2005, as collected by Global Entrepreneurship Monitor (GEM) research and Global Competitiveness Report (GCR) research, are used to identify predictors of GDP growth for emerging and developed nations. The GEM data are used to determine the effect of different types of entrepreneurship on GDP growth. The GCR data operationalize additional control variables suggested by three economic growth theories: new economic geography, endogenous growth theory and national systems of innovation. This contribution to the literature suggests that, in developed countries, a significant portion of economic growth rates can be attributed to high-expectation entrepreneurs exploiting national investments in knowledge creation and regulatory...

A computational psychiatry approach identifies how alpha-2A noradrenergic agonist Guanfacine affects feature-based reinforcement learning in the macaque.

Abstract: Noradrenaline is believed to support cognitive flexibility through the alpha 2A noradrenergic receptor (a2A-NAR) acting in prefrontal cortex. Enhanced flexibility has been inferred from improved working memory with the a2A-NA agonist Guanfacine. But it has been unclear whether Guanfacine improves specific attention and learning mechanisms beyond working memory, and whether the drug effects can be formalized computationally to allow single subject predictions. We tested and confirmed these suggestions in a case study with a healthy nonhuman primate performing a feature-based reversal learning task evaluating performance using Bayesian and Reinforcement learning models. In an initial dose-testing phase we found a Guanfacine dose that increased performance accuracy, decreased distractibility and improved learning. In a second experimental phase using only that dose we examined the faster feature-based reversal learning with Guanfacine with single-subject computational modeling. Parameter estimation suggested that improved learning is not accounted for by varying a single reinforcement learning mechanism, but by changing the set of parameter values to higher learning rates and stronger suppression of non-chosen over chosen feature information. These findings provide an important starting point for developing nonhuman primate models to discern the synaptic mechanisms of attention and learning functions within the context of a computational neuropsychiatry framework.

Subsurface denitrification in a forest riparian zone: interactions between hydrology and supplies of nitrate and organic carbon.

Abstract: The influence of hydrology andpatterns of supply of electron donors and acceptors onsubsurface denitrification was studied in a forestriparian zone along the Boyne River in southernOntario that received high nitrogen inputs from a sandaquifer. Two hypotheses were tested: (1) subsurfacedenitrification is restricted to localized zones ofhigh activity; (2) denitrification zones occur atsites where groundwater flow paths transportNO3 − to supplies of available organiccarbon. A plume of nitrate-rich groundwater withconcentrations of 10–30 mg N L−1 flowed laterallyat depths of 1.5–5 m in sands beneath peat for ahorizontal distance of 100–140 m across the riparianzone to within 30–50 m of the river. In situ acetyleneinjections to piezometers revealed that significantdenitrification was restricted to a narrow zone ofsteep NO3 − and N2O decline at theplume margins. The location of these denitrificationsites in areas with steep gradients of groundwater DOCincrease supported hypothesis 2. Many of thesedenitrification “hotspots” occurred near interfacesbetween sands and either peats or buried river channeldeposits. Field experiments involving in situadditions of either glucose or NO3 − topiezometers indicated that denitrification wasC-limited in a large subsurface area of the riparianzone, and became N-limited beyond the narrow zone ofNO3 − consumption. These data suggest thatdenitrification may not effectively removeNO3 − from groundwater transported at depththrough permeable riparian sediments unlessinteraction occurs with localized supplies of organicmatter.