Study of the inner disk of the Herbig star MWC480     

N. Jamialahmadi  B. Lopez  P. Berio  S. Flament  A. Spang 《Astrophysics and Space Science》2015,355(1):105-116

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Observations of Comet 9P/Tempel 1 around the Deep Impact event by the OSIRIS cameras onboard Rosetta     

Horst Uwe Keller  Sonia Fornasier  Stubbe F. Hviid  Jörg Knollenberg  Miriam Rengel  Gabriele Cremonese  Detlef Koschny  Ekkehard Kührt  Holger Sierks  Cesare Barbieri  Hans Rickman  Michael F. A'Hearn  Maria-Antonella Barucci  Vania da Deppo  Björn J.R. Davidsson  Stefano Debei  Fritz Gliem  José J. Lopez Moreno  Giampiero Naletto  Angel Sanz Andrés 《Icarus》2007,187(1):87-103

The OSIRIS cameras on the Rosetta spacecraft observed Comet 9P/Tempel 1 from 5 days before to 10 days after it was hit by the Deep Impact projectile. The Narrow Angle Camera (NAC) monitored the cometary dust in 5 different filters. The Wide Angle Camera (WAC) observed through filters sensitive to emissions from OH, CN, Na, and OI together with the associated continuum. Before and after the impact the comet showed regular variations in intensity. The period of the brightness changes is consistent with the rotation period of Tempel 1. The overall brightness of Tempel 1 decreased by about 10% during the OSIRIS observations. The analysis of the impact ejecta shows that no new permanent coma structures were created by the impact. Most of the material moved with . Much of it left the comet in the form of icy grains which sublimated and fragmented within the first hour after the impact. The light curve of the comet after the impact and the amount of material leaving the comet ( of water ice and a presumably larger amount of dust) suggest that the impact ejecta were quickly accelerated by collisions with gas molecules. Therefore, the motion of the bulk of the ejecta cannot be described by ballistic trajectories, and the validity of determinations of the density and tensile strength of the nucleus of Tempel 1 with models using ballistic ejection of particles is uncertain.  相似文献   

Temporal changes in tree-ring nitrogen of Pinus thunbergii trees exposed to Black-tailed Gull (Larus crassirostris) breeding colonies     

Lopez C.M. Larry  Mizota Chitoshi  Yamanaka Toshiro  Nobori Yoshihiro 《Applied Geochemistry》2010

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Le complexe filonien de Fuerteventura (Iles Canaries)     

J. Lopez Ruiz 《Bulletin of Volcanology》1969,33(4):1166-1185

Two sectors in the island have been distinguished which depend on the intensity of the penetration of the dyke swarm: the central-western sector, where the proportion of dykes in relation to the host rocks is — in some cases — more than 90% and all the rest of the island, where the dykes are in less proportion. In the central-western sector the predominant direction varies from N-10^o-E to N-20^o-E, whilst in the rest of the island a clear constant direction does not exist, although there are some directional trends more or less well defined. Most dykes are of basaltic composition, but there are also salic dykes (trachytic and phonolitic) and camptonites. The dykes from the western sector have suffered intense transformation processes (albitization and amphibolization), so that it is frequent to find dykes that do not preserve practically any one of their primary minerals. As the albitization process also affects the host rocks and has a regional development; we can speak of a regional metamorphism equivalent in its intensity to the Green Schist. Three main generations of dykes have been established: 1st) those of an approximately N-S direction, forming the older generation, constituted by multiple injections, 2nd) those genetically related to the Basaltic Series I, 3rd) those of salic composition, closely related with the syenitic-trachytic intrusions.  相似文献   

Electrical conductivity of igneous rocks: Composition and temperature relations     

R. Alvarez  J. Perez Reynoso  L. Javier Alvarez  M. Lopez Martinez 《Bulletin of Volcanology》1978,41(4):317-327

The conductivity of four igneous rocks with, 49, 65, 77, and 84% SiO₂ was measured as a function of temperature in the interval from 20° to 1280°C; measurements were made in a vacuum of 10^?3 torr. No simple relationships were found between conductivity and SiO₂ content or versus major element groupings such as Na₂O=K₂O=CaO and TiO₂=Cr₂O₃=Al₂O₃=Fe₂O₃=FeO. An analytical expression was obtained between conductivity and the albite-quartz ratio, valid for temperatures between 300° and 1200°C. It was necessary to compute the CIPW norm in order to obtain the albite and quartz percentages. The onset of melting apparently occurred between 600° and 700°C. Petrography performed on two samples after cooling showed 70 and 85% partial melting. Three conduction regions were identified: 1) below 300°C, 2) between 300°C and 600°C, and 3) above 600°C. Different activation energies obtained for the heating and cooling intervals confirm that the sample undergoes textural changes in the heating-cooling cycle. Activation energy increments of 0.1 and 0.2 eV per decade of albite-quartz ratio were obtained.  相似文献   

Relation between semen quality and rangeland diets of mixed-breed male goats     

M. Mellado  F. Pastor  R. Lopez  F. Rios 《Journal of Arid Environments》2006,66(4):727-737

The impact of range plant toxins on the reproductive performance of female cattle is economically important to the livestock industry. Nevertheless, there is little information on the significance of toxicosis from range plants on semen quality in domestic ruminants. A total of 18 adult mixed-breed bucks under range conditions were used to evaluate the effect of diet composition (microhistological analysis of fecal samples) on some semen characteristics, and blood and fecal components in April and August. Forages in the buck diets were grouped into 2 classes: low or high levels of each plant in the buck diets. Bucks with higher proportion of Acacia greggii, Flourensia cernua and Lindleya mespiloides in their diets yielded 23–50% less (p<0.05) semen than bucks with low proportion of these shrubs in their diet. Sperm motility was reduced by 3–8 percent units (p<0.05) by high levels of five rangeland shrubs in the buck diets. Bucks consuming high levels of Acacia greggii showed significantly lower percentages of normal sperm (92±10 vs. 96±3; p<0.05) than bucks with low intake of this forage. High proportions of Rhus virens and Solanum elaeagnifolium in the buck diet increased the percentage of normal sperm (5 units, p<0.05) when compared to bucks with low utilization of these forages. Increased intake of Acacia greggii, Dalea bicolor, Opuntia rastrera, Larrea tridentata and Cowania plicata reduced percentage of live sperm by 5 units (p<0.05). Blood metabolites analysis showed that increased levels of Acacia greggii and Parthenium incanum were related to better nutritional status of bucks. Zn (−), Cu (−) and glucose (+) were significant predictors of semen volume (r²=0.30). Cu (−) and cholesterol (−) accounted for 37% of the variation in percentage of normal sperms. Forty-four percent of the variation in secondary abnormalities was accounted by Zn (+) and cholesterol (+), whereas fecal N, serum total proteins and creatinine positively affected percentage of live sperms (r²=0.37). These results indicate that semen quality and metabolic profiles of grazing bucks were sensitive to the ingestion of some Chihuahuan desert forages.  相似文献   

Relationship between subcellular cadmium distribution in prey and cadmium trophic transfer to a predator   总被引：1，自引：0，他引：1  

William G. Wallace  Glenn R. Lopez 《Estuaries and Coasts》1996,19(4):923-930

We tested the hypothesis that exposure-related alterations in the subcellular Cd distribution in prey relate to changes in Cd absorption by a predator. Oligochaete worms,Limnodrilus hoffmeisteri were exposed for 1 wk or 6 wk to 0.5 μg Cd 1^?1, 47 μg Cd 1^?1, or 140 μg Cd 1^?1 (including¹⁰⁹Cd as a tracer) and relationships between oligochaete subcellular Cd distribution and Cd absorption by a predator, the grass shrimp (Palaemonetes pugio), were determined. Concentration and duration of Cd exposure had direct effects on oligochaete subcellular Cd distribution. Changes in oligochaete subcellular Cd distribution were characterized by increases in both the amount and proportion of Cd bound to the cytosolic fraction. The induction of Cd-binding proteins (e.g., metallothioneins) were suspected to be responsible for these changes. We found 1∶1 relationships between the amount and percentage of Cd in oligochaete cytosol and the amount and percentage of Cd adsorbed by shrimp. These results demonstrate that only metal bound to the soluble fraction of prey is available to higher trophic levels, and that factors influencing subcellular metal distribution in prey will directly alter metal trophic transfer to predators.  相似文献   

Interactions between the Laramide Foreland and the passive margin of the Gulf of Mexico: Tectonics and sedimentation in the Golden Lane area,Veracruz State,Mexico     

Humberto Alzaga-Ruiz  Michel Lopez  François Roure  Michel Séranne 《Marine and Petroleum Geology》2009

This paper focuses on the analyses of the clastic sedimentary infill of the Coastal Plain of Eastern Mexico, which initiated synchronously with the Laramide orogeny in the vicinity of the Golden Lane. Results of these analyses are used as boundary conditions for calibrating/interpreting seismic profiles across more distal depocenters in the offshore of the Gulf of Mexico, from the sea shore and continental slope in the west to the abyssal plain in the east. The objective of the study is to better predict the reservoir distribution in the Deep offshore Basin of the Gulf of Mexico (DBGM), in order to explore for petroleum.  相似文献   

Snowmelt and the hydrological interaction of forest–grassland ecosystems in Central Yakutia,eastern Siberia          下载免费PDF全文

M. L. Lopez Caceres  F. Takakai  G. Iwahana  A. N. Fedorov  Y. Iijima  R. Hatano  M. Fukuda 《水文研究》2015,29(14):3074-3083

In the last two decades the major focus of study in forest water and carbon balances in eastern Siberia has been on the effect of rain during the growing season. Little attention has been paid to the contribution of snowmelt water. The results of the present study indicate that weather conditions during the snowmelt period as well as the soil moisture conditions carried from the previous year's growing season strongly determined the water availability for the forest ecosystem at the beginning of the next growing season. In the forest–grassland intermingled ecosystem of lowland Central Yakutia, gradual snowmelt water flow from the forest into the adjacent grassland depressions increased when soil moisture was high and air temperature was low, whereas low soil moisture and high air temperatures accelerated soil thawing and consequently snowmelt water infiltration into the forest soil. We found that snow depth did not determine the volume of snowmelt water moving to the grassland depression since the thermokarst lake water level in the adjacent grassland was about 25 cm lower in 2005 than in May 2006, even though maximum snow depth reached 57 cm and 43 cm in the winter of 2004–05 and 2005–06, respectively. The contribution of snowmelt water to forest growth as well as the flow of water from the forest to the grasslands showed a strong annual variability. We conclude that warmer springs and high variability in precipitation regimes as a result of climate change will result in more snowmelt water infiltration into the forest soil when the previous year's precipitation is low while more snowmelt water will flow into the thermokarst lake when the previous year's precipitation is high. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Correction to: Modelling effects of an asphalt road at a dike crest on dike cover erosion onset during wave overtopping     

Bomers  A.  Aguilar Lopez  J. P.  Warmink  J. J.  Hulscher  S. J. M. H. 《Natural Hazards》2018,94(1):493-493

Natural Hazards - The article was published Open Access under the Dutch Compact Agreement; however, due to an internal system error, previous HTML rendering of the article did not reflect this.  相似文献