GONG Observations of Solar Surface Flows     

DH Hathaway  PA Gilman  JW Harvey  F Hill  RF Howard  HP Jones  JC Kasher  JW Leibacher  JA Pintar  GW Simon 《Science (New York, N.Y.)》1996,272(5266):1306-1309

Doppler velocity observations obtained by the Global Oscillation Network Group (GONG) instruments directly measure the nearly steady flows in the solar photosphere. The sun's differential rotation is accurately determined from single observations. The rotation profile with respect to latitude agrees well with previous measures, but it also shows a slight north-south asymmetry. Rotation profiles averaged over 27-day rotations of the sun reveal the torsional oscillation signal-weak, jetlike features, with amplitudes of 5 meters per second, that are associated with the sunspot latitude activity belts. A meridional circulation with a poleward flow of about 20 meters per second is also evident. Several characteristics of the surface flows suggest the presence of large convection cells.  相似文献   

Stimulation of food species growth by limpet mucus     

Connor VM  Quinn JF 《Science (New York, N.Y.)》1984,225(4664):843-844

The trails of mucus secreted by certain species of intertidal limpets serve as adhesive traps for the microalgae that are their primary food resource. In addition, the mucus trails of two solitary homing limpets, Lottia gigantea and Collisella scabra, stimulate growth of the microalgae that the limpets consume. In contrast, the trails of an aggregating limpet, Collisella digitalis, do not stimulate microalgal growth. These results and their possible ecological significance are interpreted in light of the differences in the behavioral repertoires of the three limpet species.  相似文献   

Hydra-headed pesticides     

E D Dickinson JC  J W Parker 《Science (New York, N.Y.)》1971,171(966):16-18

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Predicting and observing el nino     

Wyrtki K  Stroup E  Patzert W  Williams R  Quinn W 《Science (New York, N.Y.)》1976,191(4225):343-346

In October 1974 the occurrence of a weak El Ni?o event was predicted for early 1975 on the basis of the southern oscillation index. An expedition was organized to observe the event in the waters off Peru and Ecuador during two cruises in order to study its occurrence and its development with time. During the first cruise a massive transgression of warm low salinity water across the equator to 4 degrees S was observed, as well as a depression of the thermocline along the equator and off the coast of South America, indicating the start of El Ni?o development. During the second cruise the oceanographic situation had changed and conditions were returning to normal.  相似文献   

Rapid formation of supermassive black hole binaries in galaxy mergers with gas     

Mayer L  Kazantzidis S  Madau P  Colpi M  Quinn T  Wadsley J 《Science (New York, N.Y.)》2007,316(5833):1874-1877

Supermassive black holes (SMBHs) are a ubiquitous component of the nuclei of galaxies. It is normally assumed that after the merger of two massive galaxies, a SMBH binary will form, shrink because of stellar or gas dynamical processes, and ultimately coalesce by emitting a burst of gravitational waves. However, so far it has not been possible to show how two SMBHs bind during a galaxy merger with gas because of the difficulty of modeling a wide range of spatial scales. Here we report hydrodynamical simulations that track the formation of a SMBH binary down to scales of a few light years after the collision between two spiral galaxies. A massive, turbulent, nuclear gaseous disk arises as a result of the galaxy merger. The black holes form an eccentric binary in the disk in less than 1 million years as a result of the gravitational drag from the gas rather than from the stars.  相似文献   

Calibrated membranes with coated pore walls   总被引：1，自引：0，他引：1  

W J Petzny  J A Quinn 《Science (New York, N.Y.)》1969,166(906):751-753

Extremely uniform small-radius pores, formed in thin mica membranes, have been coated with monoand multimolecular layers of fatty acids. Stearate monolayers orient themselves on the pore walls in layers 25 to 28 angstroms thick. The resulting membranes, with radii of the order 100 angstroms or less, may have applications in simulating certain features of biological membranes and in fabricating highly selective membranes for differential dialysis or ultrafiltration.  相似文献   

KOI-126: a triply eclipsing hierarchical triple with two low-mass stars     

Carter JA  Fabrycky DC  Ragozzine D  Holman MJ  Quinn SN  Latham DW  Buchhave LA  Van Cleve J  Cochran WD  Cote MT  Endl M  Ford EB  Haas MR  Jenkins JM  Koch DG  Li J  Lissauer JJ  MacQueen PJ  Middour CK  Orosz JA  Rowe JF  Steffen JH  Welsh WF 《Science (New York, N.Y.)》2011,331(6017):562-565

The Kepler spacecraft has been monitoring the light from 150,000 stars in its primary quest to detect transiting exoplanets. Here, we report on the detection of an eclipsing stellar hierarchical triple, identified in the Kepler photometry. KOI-126 [A, (B, C)], is composed of a low-mass binary [masses M(B) = 0.2413 ± 0.0030 solar mass (M(⊙)), M(C) = 0.2127 ± 0.0026 M(⊙); radii R(B) = 0.2543 ± 0.0014 solar radius (R(⊙)), R(C) = 0.2318 ± 0.0013 R(⊙); orbital period P(1) = 1.76713 ± 0.00019 days] on an eccentric orbit about a third star (mass M(A) = 1.347 ± 0.032 M(⊙); radius R(A) = 2.0254 ± 0.0098 R(⊙); period of orbit around the low-mass binary P(2) = 33.9214 ± 0.0013 days; eccentricity of that orbit e(2) = 0.3043 ± 0.0024). The low-mass pair probe the poorly sampled fully convective stellar domain offering a crucial benchmark for theoretical stellar models.  相似文献   

The protein kinase family: conserved features and deduced phylogeny of the catalytic domains   总被引：583，自引：0，他引：583  

S K Hanks  A M Quinn  T Hunter 《Science (New York, N.Y.)》1988,241(4861):42-52

In recent years, members of the protein kinase family have been discovered at an accelerated pace. Most were first described, not through the traditional biochemical approach of protein purification and enzyme assay, but as putative protein kinase amino acid sequences deduced from the nucleotide sequences of molecularly cloned genes or complementary DNAs. Phylogenetic mapping of the conserved protein kinase catalytic domains can serve as a useful first step in the functional characterization of these newly identified family members.  相似文献   

Mars-like soils in the Atacama Desert, Chile, and the dry limit of microbial life     

Navarro-González R  Rainey FA  Molina P  Bagaley DR  Hollen BJ  de la Rosa J  Small AM  Quinn RC  Grunthaner FJ  Cáceres L  Gomez-Silva B  McKay CP 《Science (New York, N.Y.)》2003,302(5647):1018-1021

The Viking missions showed the martian soil to be lifeless and depleted in organic material and indicated the presence of one or more reactive oxidants. Here we report the presence of Mars-like soils in the extreme arid region of the Atacama Desert. Samples from this region had organic species only at trace levels and extremely low levels of culturable bacteria. Two samples from the extreme arid region were tested for DNA and none was recovered. Incubation experiments, patterned after the Viking labeled-release experiment but with separate biological and nonbiological isomers, show active decomposition of organic species in these soils by nonbiological processes.  相似文献   

Rapid evolution of reproductive isolation in the wild: evidence from introduced salmon     

Hendry AP  Wenburg JK  Bentzen P  Volk EC  Quinn TP 《Science (New York, N.Y.)》2000,290(5491):516-519

Colonization of new environments should promote rapid speciation as a by-product of adaptation to divergent selective regimes. Although this process of ecological speciation is known to have occurred over millennia or centuries, nothing is known about how quickly reproductive isolation actually evolves when new environments are first colonized. Using DNA microsatellites, population-specific natural tags, and phenotypic variation, we tested for reproductive isolation between two adjacent salmon populations of a common ancestry that colonized divergent reproductive environments (a river and a lake beach). We found evidence for the evolution of reproductive isolation after fewer than 13 generations.  相似文献