Institution
York University
Education•Toronto, Ontario, Canada•
About: York University is a education organization based out in Toronto, Ontario, Canada. It is known for research contribution in the topics: Population & Politics. The organization has 18899 authors who have published 43357 publications receiving 1568560 citations.
Papers published on a yearly basis
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University of Colorado Boulder1, New Mexico Highlands University2, California Institute of Technology3, Norwegian Institute for Air Research4, Cooperative Institute for Research in Environmental Sciences5, Harvard University6, Chalmers University of Technology7, York University8, Langley Research Center9, Hampton University10
TL;DR: In this paper, the authors examined the temporal evolution of the enhancements, to place them in historical context, and to investigate their origin, suggesting that energetic particle precipitation led to substantial NOx production in the upper atmosphere beginning with the remarkable solar storms and possibly persisting through January.
Abstract: Upper stratospheric enhancements in NOx (NO and NO2) were observed at high northern latitudes from March through at least July of 2004. Multi-satellite data analysis is used to examine the temporal evolution of the enhancements, to place them in historical context, and to investigate their origin. The enhancements were a factor of 4 higher than nominal at some locations, and are unprecedented in the northern hemisphere since at least 1985. They were accompanied by reductions in O-3 of more than 60% in some cases. The analysis suggests that energetic particle precipitation led to substantial NOx production in the upper atmosphere beginning with the remarkable solar storms in late October 2003 and possibly persisting through January. Downward transport of the excess NOx, facilitated by unique meteorological conditions in 2004 that led to an unusually strong upper stratospheric vortex from late January through March, caused the enhancements.
277 citations
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05 Dec 2005TL;DR: The simple periodic server dominates both sporadic and deferrable servers when the metric is application task schedulability.
Abstract: This paper focuses on the hierarchical scheduling of systems where a number of separate applications reside on a single processor. It addresses the particular case where fixed priority pre-emptive scheduling is used at both global and local levels, with a server associated with each application. Using response time analysis, an exact schedulability test is derived for application tasks. This test improves on previously published work. The analysis is extended to the case of harmonic tasks that can be bound to the release of their server. These tasks exhibit improved schedulability indicating that it is advantageous to choose server periods that enable some tasks to be bound to the release of their server. The use of periodic, sporadic and deferrable servers is considered with the conclusion that the simple periodic server dominates both sporadic and deferrable servers when the metric is application task schedulability
277 citations
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TL;DR: Bats roosted in western white pine, and to a lesser extent ponderosa pine and western larch, in intermediate stages of decay more often than would be expected at random.
Abstract: We used radiotelemetry to examine the roost-site preferences of four species of tree-roosting bats (Eptesicus fuscus, Lasionycteris noctivagans, Myotis evotis, and M. volans) in southern British Co...
277 citations
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277 citations
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TL;DR: This paper presents a new algorithm for the global retrieval of LAI where the bidirectional reflectance distribution function (BRDF) is considered explicitly in the algorithm and hence removing the need of doing BRDF corrections and normalizations to the input images.
Abstract: Leaf area index (LAI) is one of the most important Earth surface parameters in modeling ecosystems and their interaction with climate. Based on a geometrical optical model (Four-Scale) and LAI algorithms previously derived for Canada-wide applications, this paper presents a new algorithm for the global retrieval of LAI where the bidirectional reflectance distribution function (BRDF) is considered explicitly in the algorithm and hence removing the need of doing BRDF corrections and normalizations to the input images. The core problem of integrating BRDF into the LAI algorithm is that nonlinear BRDF kernels that are used to relate spectral reflectances to LAI are also LAI dependent, and no analytical solution is found to derive directly LAI from reflectance data. This problem is solved through developing a simple iteration procedure. The relationships between LAI and reflectances of various spectral bands (red, near infrared, and shortwave infrared) are simulated with Four-Scale with a multiple scattering scheme. Based on the model simulations, the key coefficients in the BRDF kernels are fitted with Chebyshev polynomials of the second kind. Spectral indices - the simple ratio and the reduced simple ratio - are used to effectively combine the spectral bands for LAI retrieval. Example regional and global LAI maps are produced. Accuracy assessment on a Canada-wide LAI map is made in comparison with a previously validated 1998 LAI map and ground measurements made in seven Landsat scenes
276 citations
Authors
Showing all 19301 results
Name | H-index | Papers | Citations |
---|---|---|---|
Dan R. Littman | 157 | 426 | 107164 |
Martin J. Blaser | 147 | 820 | 104104 |
Aaron Dominguez | 147 | 1968 | 113224 |
Gregory R Snow | 147 | 1704 | 115677 |
Joseph E. LeDoux | 139 | 478 | 91500 |
Kenneth Bloom | 138 | 1958 | 110129 |
Osamu Jinnouchi | 135 | 885 | 86104 |
Steven A. Narod | 134 | 970 | 84638 |
David H. Barlow | 133 | 786 | 72730 |
Elliott Cheu | 133 | 1219 | 91305 |
Roger Moore | 132 | 1677 | 98402 |
Wendy Taylor | 131 | 1252 | 89457 |
Stephen P. Jackson | 131 | 372 | 76148 |
Flera Rizatdinova | 130 | 1242 | 89525 |
Sudhir Malik | 130 | 1669 | 98522 |