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Institution

Concordia University

EducationMontreal, Quebec, Canada
About: Concordia University is a education organization based out in Montreal, Quebec, Canada. It is known for research contribution in the topics: Control theory & Population. The organization has 13565 authors who have published 31084 publications receiving 783525 citations. The organization is also known as: Sir George Williams University & Loyola College, Montreal.


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Journal ArticleDOI
TL;DR: The results support the view that motor control in aging is influenced by executive control and have implications for theories of cognitive training and transfer, and are the first to demonstrate training-related benefits to gross motor performance stemming from cognitive dual-task training.
Abstract: Background. There is growing evidence of the involvement of executive control in the maintenance of balance in old age. We examined whether healthy older adults who completed five sessions of nonmotor cognitive dual-task training would show significant improvements on measures of dual-task standing balance and mobility, compared with an un trained control group. Methods. T wenty healthy older adults were assigned to either training or control groups. In the pre- and post-training sessions, all participants performed tests of cognition, balance, and mobility (single-support balance, dynamic posturography, sit-to-stand, 40-foot walk) under single- and dual-task conditions. The training group completed five sessions of cognitive dual-task training spaced at least 2 days apart. The two tasks involved making two-choice decisions to visually presented stimuli. Participants completed multiple blocks of single-task (task A or B, blockwise) and mixed (A, B, or A + B) trials in each training session. Results. The training group showed significant improvements in body sway during single-support balance and center of gravity alignment during double-support dynamic balance. The control group showed no appreciable improvements.

183 citations

Journal ArticleDOI
TL;DR: A new measure to determine homogeneous blocks and a new structure analyzer for rejecting blocks with structure based on high-pass operators and special masks for corners to stabilize the homogeneity estimation are proposed.
Abstract: Noise can significantly impact the effectiveness of video processing algorithms. This paper proposes a fast white-noise variance estimation that is reliable even in images with large textured areas. This method finds intensity-homogeneous blocks first and then estimates the noise variance in these blocks, taking image structure into account. This paper proposes a new measure to determine homogeneous blocks and a new structure analyzer for rejecting blocks with structure. This analyzer is based on high-pass operators and special masks for corners to stabilize the homogeneity estimation. For typical video quality (PSNR of 20-40 dB), the proposed method outperforms other methods significantly and the worst-case estimation error is 3 dB, which is suitable for real applications such as video broadcasts. The method performs well both in highly noisy and good-quality images. It also works well in images including few uniform blocks.

182 citations

Journal ArticleDOI
TL;DR: The results of experiment 2, showing that sensitization to amphetamine was blocked by MK-801 even when conditioning was prevented, suggest that the two effects ofMK-801 are independent, and may implicate different sites of action.
Abstract: The non-competitive N-methyl-d-aspartate (NMDA) receptor antagonist, MK-801, has been shown to block the development of sensitization of the behavioral activating effects of amphetamine. Three experiments were designed to determine in rats whether MK-801 had its effects through interference with long-term changes underlying sensitization, per se, or through interference with the development of conditioning of the drug effect to the environment where the drug was given. In experiment 1, conditioning was promoted by explicitly pairing amphetamine (1.5 mg/kg, IP) with the testing environment. In experiment 2, a random-pairing procedure was used to eliminate the possibility of association between the drug and a specific context. Experiment 3 was carried out to assess the duration of the blockade of sensitization by MK-801. The effect of MK-801 (0.25 mg/kg, IP) during amphetamine pre-exposure was studied in tests for conditioning (following saline injections, experiment 1) and in tests for sensitization (following 0.75 mg/kg amphetamine, experiments 1, 2 and 3). It was found in experiment 1 that MK-801 given with amphetamine during the amphetamine pre-exposure phase blocked the development of both conditioning activity and environment-specific sensitization to amphetamine. The results of experiment 2, showing that sensitization to amphetamine was blocked by MK-801 even when conditioning was prevented, suggest that the two effects of MK-801 are independent, and may implicate different sites of action. Experiment 3 showed that the blockade of sensitization by MK-801 was evident in tests made 10 days after pre-exposure to amphetamine, supporting the view that MK-801 interferes with long-term changes underlying sensitization to amphetamine.

182 citations

Journal ArticleDOI
TL;DR: The combined reduction in spermatogonial cell nests and nursing cells suggest that a pulse exposure to 21 μg/L of atrazine during sexual differentiation could significantly reduce reproduction during the reproductive life of these animals.
Abstract: Xenopus laevis tadpoles (stage 56) were exposed to 21 microg/L atrazine under laboratory-controlled conditions in a static system. Following a 48-h exposure period at 21+/-0.5 degrees C during sexual differentiation, tadpoles were fixed, and the kidney-gonad complex was microdissected. Quantitative histological analysis revealed in atrazine-exposed ovaries a significant (p < 0.05) increase in frequency of secondary oogonia. Atresia, or oogonial resorption of both primary and secondary oogonia, also increased significantly (p < 0.05). The results suggest that these primary germ cells, which constitute the total number of germ cells in the ovary for the reproductive life of the organism, were reduced by 20% following a 48-h exposure period compared to 2% in controls.

182 citations

Journal ArticleDOI
TL;DR: Preliminary evidence suggests that intact serotonergic transmission is important in morphine place conditioning, and further study may reveal an interesting dissociation of serotonin's role in the rewarding effects of psychomotor stimulants and opiates.

182 citations


Authors

Showing all 13754 results

NameH-indexPapersCitations
Alan C. Evans183866134642
Michael J. Meaney13660481128
Chao Zhang127311984711
Charles Spence11194951159
Angappa Gunasekaran10158640633
Kaushik Roy97140242661
Muthiah Manoharan9649744464
Stephen J. Simpson9549030226
Roy A. Wise9525239509
Dario Farina9483232786
Yavin Shaham9423929596
Elazer R. Edelman8959329980
Fikret Berkes8827149585
Ke Wu87124233226
Nick Serpone8547430532
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
202375
2022343
20211,859
20201,861
20191,734
20181,680