Flying over the farm: understanding drone adoption by Australian irrigators     

Zuo  Alec  Wheeler  Sarah Ann  Sun  Heng 《Precision Agriculture》2021,22(6):1973-1991

Precision Agriculture - As part of a precision agricultural approach, drones have increasingly been employed within agriculture for more than a decade and are shown to provide many benefits....  相似文献   

Eddy/wind interactions stimulate extraordinary mid-ocean plankton blooms   总被引：1，自引：0，他引：1  

McGillicuddy DJ  Anderson LA  Bates NR  Bibby T  Buesseler KO  Carlson CA  Davis CS  Ewart C  Falkowski PG  Goldthwait SA  Hansell DA  Jenkins WJ  Johnson R  Kosnyrev VK  Ledwell JR  Li QP  Siegel DA  Steinberg DK 《Science (New York, N.Y.)》2007,316(5827):1021-1026

Episodic eddy-driven upwelling may supply a significant fraction of the nutrients required to sustain primary productivity of the subtropical ocean. New observations in the northwest Atlantic reveal that, although plankton blooms occur in both cyclones and mode-water eddies, the biological responses differ. Mode-water eddies can generate extraordinary diatom biomass and primary production at depth, relative to the time series near Bermuda. These blooms are sustained by eddy/wind interactions, which amplify the eddy-induced upwelling. In contrast, eddy/wind interactions dampen eddy-induced upwelling in cyclones. Carbon export inferred from oxygen anomalies in eddy cores is one to three times as much as annual new production for the region.  相似文献   

Hollows on Mercury: MESSENGER evidence for geologically recent volatile-related activity     

Blewett DT  Chabot NL  Denevi BW  Ernst CM  Head JW  Izenberg NR  Murchie SL  Solomon SC  Nittler LR  McCoy TJ  Xiao Z  Baker DM  Fassett CI  Braden SE  Oberst J  Scholten F  Preusker F  Hurwitz DM 《Science (New York, N.Y.)》2011,333(6051):1856-1859

High-resolution images of Mercury's surface from orbit reveal that many bright deposits within impact craters exhibit fresh-appearing, irregular, shallow, rimless depressions. The depressions, or hollows, range from tens of meters to a few kilometers across, and many have high-reflectance interiors and halos. The host rocks, which are associated with crater central peaks, peak rings, floors, and walls, are interpreted to have been excavated from depth by the crater-forming process. The most likely formation mechanisms for the hollows involve recent loss of volatiles through some combination of sublimation, space weathering, outgassing, or pyroclastic volcanism. These features support the inference that Mercury's interior contains higher abundances of volatile materials than predicted by most scenarios for the formation of the solar system's innermost planet.  相似文献   

Regulation of cell migration by the C2 domain of the tumor suppressor PTEN     

Raftopoulou M  Etienne-Manneville S  Self A  Nicholls S  Hall A 《Science (New York, N.Y.)》2004,303(5661):1179-1181

PTEN is a tumor suppressor protein that dephosphorylates phosphatidylinositol 3,4,5 trisphosphate and antagonizes the phosphatidylinositol-3 kinase signaling pathway. We show here that PTEN can also inhibit cell migration through its C2 domain, independent of its lipid phosphatase activity. This activity depends on the protein phosphatase activity of PTEN and on dephosphorylation at a single residue, threonine(383). The ability of PTEN to control cell migration through its C2 domain is likely to be an important feature of its tumor suppressor activity.  相似文献   

The response of vegetation on the Andean flank in western Amazonia to Pleistocene climate change   总被引：1，自引：0，他引：1  

Cárdenas ML  Gosling WD  Sherlock SC  Poole I  Pennington RT  Mothes P 《Science (New York, N.Y.)》2011,331(6020):1055-1058

A reconstruction of past environmental change from Ecuador reveals the response of lower montane forest on the Andean flank in western Amazonia to glacial-interglacial global climate change. Radiometric dating of volcanic ash indicates that deposition occurred ~324,000 to 193,000 years ago during parts of Marine Isotope Stages 9, 7, and 6. Fossil pollen and wood preserved within organic sediments suggest that the composition of the forest altered radically in response to glacial-interglacial climate change. The presence of Podocarpus macrofossils ~1000 meters below the lower limit of their modern distribution indicates a relative cooling of at least 5°C during glacials and persistence of wet conditions. Interglacial deposits contain thermophilic palms suggesting warm and wet climates. Hence, global temperature change can radically alter vegetation communities and biodiversity in this region.  相似文献   

NMR detection of structures in the HIV-1 5'-leader RNA that regulate genome packaging     

Lu K  Heng X  Garyu L  Monti S  Garcia EL  Kharytonchyk S  Dorjsuren B  Kulandaivel G  Jones S  Hiremath A  Divakaruni SS  LaCotti C  Barton S  Tummillo D  Hosic A  Edme K  Albrecht S  Telesnitsky A  Summers MF 《Science (New York, N.Y.)》2011,334(6053):242-245

The 5'-leader of the HIV-1 genome regulates multiple functions during viral replication via mechanisms that have yet to be established. We developed a nuclear magnetic resonance approach that enabled direct detection of structural elements within the intact leader (712-nucleotide dimer) that are critical for genome packaging. Residues spanning the gag start codon (AUG) form a hairpin in the monomeric leader and base pair with residues of the unique-5' region (U5) in the dimer. U5:AUG formation promotes dimerization by displacing and exposing a dimer-promoting hairpin and enhances binding by the nucleocapsid (NC) protein, which is the cognate domain of the viral Gag polyprotein that directs packaging. Our findings support a packaging mechanism in which translation, dimerization, NC binding, and packaging are regulated by a common RNA structural switch.  相似文献   

Generation of spatial patterns through cell polarity switching     

Robinson S  Barbier de Reuille P  Chan J  Bergmann D  Prusinkiewicz P  Coen E 《Science (New York, N.Y.)》2011,333(6048):1436-1440

  相似文献   

Recently formed polyploid plants diversify at lower rates     

Mayrose I  Zhan SH  Rothfels CJ  Magnuson-Ford K  Barker MS  Rieseberg LH  Otto SP 《Science (New York, N.Y.)》2011,333(6047):1257

Polyploidy, the doubling of genomic content, is a widespread feature, especially among plants, yet its macroevolutionary impacts are contentious. Traditionally, polyploidy has been considered an evolutionary dead end, whereas recent genomic studies suggest that polyploidy has been a key driver of macroevolutionary success. We examined the consequences of polyploidy on the time scale of genera across a diverse set of vascular plants, encompassing hundreds of inferred polyploidization events. Likelihood-based analyses indicate that polyploids generally exhibit lower speciation rates and higher extinction rates than diploids, providing the first quantitative corroboration of the dead-end hypothesis. The increased speciation rates of diploids can, in part, be ascribed to their capacity to speciate via polyploidy. Only particularly fit lineages of polyploids may persist to enjoy longer-term evolutionary success.  相似文献   

Treatment of feline herpesvirus-1 associated disease in cats with famciclovir and related drugs     

Richard Malik  Naomi S. Lessels  Sarah Webb  Mirim Meek  Paul Gotis Graham  Carlo Vitale  Jacqueline M. Norris  Helen Power 《Journal of Feline Medicine and Surgery》2009,11(1):40-48

  相似文献   

Features of domestic dog demography relevant to rabies control planning in tanzania     

Alena Gsell  Darryn L. Knobel  Sarah Cleaveland  Rudovick R. Kazwala  Penelope Vounatsou  Jakob Zinsstag 《Journal of Veterinary Behavior: Clinical Applications and Research》2009,4(2):63-64

  相似文献