3,089 research outputs found
Satellite remote sensing of vegetation dynamics in the context of climate change
Vegetation is a key component of the Earth's climate system. Understanding vegetation dynamics in a changing climate requires both in situ and remote sensing data. Satellite remote sensing is especially indispensible for continuous monitoring of vegetation over large areas. This dissertation is focused on investigation of vegetation dynamics in the broader context of climate change using satellite data over two critical regions: the arctic-boreal area in the northern high latitudes and Amazonia in South America.
The northern high latitudes have experienced amplified warming. We found the response of the arctic-boreal vegetation to this warming to be different between North America and Eurasia during a 30-year period since 1982: the relationship between vegetation green-up and temperature rise was stable over Eurasia, but in North America, the amount of vegetation green-up per unit amount of warming has decreased since the beginning of 21st century. This could partly be explained by the unmatched northward movements of temperature and precipitation patterns in North America.
The Amazonian rainforests have highly dense canopies of green leaves. In such dense media, reflection of solar radiation tends to saturate. Thus, the satellite measurements are weakly sensitive to vegetation changes. At the same time, the data are strongly influenced by changing sun-sensor geometry. This makes it difficult to discriminate between vegetation changes and sun-sensor geometry effects. We developed a new physically based approach to detect changes in dense forests. Analyses of several years of data from three sensors on two satellites under a range of sun-sensor geometries provide robust evidence for a sunlight driven seasonal cycle in structure and greenness of Amazonian rainforests.
The 2005 and 2010 dry-season droughts decreased the photosynthetic activity of Amazonian rainforests. We demonstrate that satellite data capture such decreases. Furthermore, we show that in 2004 and 2007, when there was lower wet-season water abundance compared to normal years, the photosynthetic activity of Amazonian forests also decreased. Potentially frequent water deficits over Amazon in the future, irrespective of whether they occur in the dry or wet season, will decrease the photosynthetic activity of Amazonian forests, and provide a positive feedback to global warming
(E)-3-DimethylÂamino-1-(2-thienÂyl)prop-2-en-1-one
The molÂecular skeleton of the title molÂecule, C9H11NOS, is essentially planar: the thioÂphene ring is inclined to the mean plane of the rest non-H atoms by 2.92â
(3)°. The crystal packing exhibits no significantly short interÂmolecular contacts
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Resistance status of the carmine spider mite, Tetranychus cinnabarinus and the twospotted spider mite, Tetranychus urticae to selected acaricides on strawberries.
The carmine spider mite, Tetranychus cinnabarinus (Boisduval) and the twospotted spider mite, Tetranychus urticae Koch, are serious pests of strawberries and many other horticultural crops. Control of these pests has been heavily dependent upon chemical acaricides. Objectives of this study were to determine the resistance status of these two pest species to commonly used acaricides on strawberries in a year-round intensive horticultural production region. LC90 of abamectin for adult carmine spider mites was 4% whereas that for adult twospotted spider mites was 24% of the top label rate. LC90s of spiromesifen, etoxazole, hexythiazox and bifenazate were 0.5%, 0.5%, 1.4% and 83% of their respective highest label rates for carmine spider mite eggs, 0.7%, 2.7%, 12.1% and 347% of their respective highest label rates for the nymphs. LC90s of spiromesifen, etoxazole, hexythiazox and bifenazate were 4.6%, 11.1%, 310% and 62% of their respective highest label rates for twospotted spider mite eggs, 3%, 13%, 432,214% and 15% of their respective highest label rates for the nymphs. Our results suggest that T. cinnabarinus have developed resistance to bifenazate and that the T. urticae have developed resistance to hexythiazox. These results strongly emphasize the need to develop resistance management strategies in the region
Deconfined Quantum Critical Point on the Triangular Lattice
We first propose a topological term that captures the "intertwinement"
between the standard "" antiferromagnetic order (or
the so-called 120 state) and the "" valence
solid bond (VBS) order for spin-1/2 systems on a triangular lattice. Then using
a controlled renormalization group calculation, we demonstrate that there
exists an unfine-tuned direct continuous deconfined quantum critical point
(dQCP) between the two ordered phases mentioned above. This dQCP is described
by the quantum electrodynamics (QED) with an emergent
PSU(4)=SU(4)/ symmetry only at the critical point. The topological term
aforementioned is also naturally derived from the QED. We also point
out that physics around this dQCP is analogous to the boundary of a
bosonic symmetry protected topological state with on-site symmetries only
Interfacial tension measurements of n-dodecane/CO2 from (298.15 to 573.15) K at pressures up to 10 MPa by pendant drop method
Key Points in Implementation of Knowledge Management and its Solutions
In knowledge-base economy era, knowledge becomes the most important resource for enterprise instead of physical labor, capital and natural resources. The success of the enterprise depends more and more on the quantity and quality of knowledge owned by it. The core competitiveness originates from employeesâ innovation ability which comes from knowledge accumulation and knowledge management. How to manage the knowledge possessed by the enterprise and how to make it becoming the sustaining competitive advantages for the enterprise? This is a new problem we must face. Finding the key points of knowledge management and plan the solution path are the crux to settle this problem. Key words: Knowledge; Knowledge Management; Innovation; Competitiveness RĂ©sumĂ©: Dans lâ Ăšre de lâĂ©conomie de la connaissance, la connaissance devient la ressource la plus importante pour les entreprises au lieu de travail physique, des capitaux et des ressources naturelles. Le succĂšs de l'entreprise dĂ©pend de plus en plus de la quantitĂ© et de la qualitĂ© de la connaissance dĂ©tenue par elle mĂȘme. Les compĂ©titivitĂ©s principales viennent de la capacitĂ© d'innovation des employĂ©s qui provient de l'accumulation des connaissances et la gestion des connaissances. Comment faire pour gĂ©rer les connaissances possĂ©dĂ©es par l'entreprise et comment faire pour quâelles deviennent des avantages concurrentiels soutenus pour l'entreprise? Il s'agit d'un nouveau problĂšme Ă qui nous devons faire face. Pour rĂ©gler ce problĂšme, il faut trouver les points clĂ©s de la gestion des connaissances et planifier les moyens de solution. Mots-ClĂ©s: connaissances; gestion des connaissances; innovation; compĂ©titivitĂ©
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