Telescope and instrument robotization at Dome C     

K. G. Strassmeier  K. Agabi  L. Agnoletto  A. Allan  M. I. Andersen  W. Ansorge  F. Bortoletto  R. Briguglio  J.‐T. Buey  S. Castellini  V. Coud du Foresto  L. Dam  H. J. Deeg  C. Eiroa  G. Durand  D. Fappani  M. Frezzotti  T. Granzer  A. Grschke  H. J. Krcher  R. Lenzen  A. Mancini  C. Montanari  A. Mora  A. Pierre  O. Pirnay  F. Roncella  F.‐X. Schmider  I. Steele  J. W. V. Storey  N. F. H. Tothill  T. Travouillon  L. Vittuari  M. Weber 《Astronomische Nachrichten》2007,328(6):451-474

This article reviews the situation for robotization of telescopes and instruments at the Antarctic station Concordia on Dome C. A brain‐storming meeting was held in Tenerife in March 2007 from which this review emerged.We describe and summarize the challenges for night‐time operations of various astronomical experiments at conditions “between Earth and Space” and conclude that robotization is likely a prerequisite for continuous astronomical data taking during the 2000‐hour night at Dome C. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

Dynamics and fluxes of organic carbon and nitrogen in two Guiana Shield river basins impacted by deforestation and mining activities          下载免费PDF全文

Marjorie Gallay  Abrahan Mora  Jean‐Michel Martinez  Antoine Gardel  Alain Laraque  Max Sarrazin  Eric Beaucher  Jean‐Claude Doudou  Christelle Lagane 《水文研究》2018,32(1):17-29

Deforestation and mining activities have proven to be very damaging to rivers because these activities disturb the environmental characteristics of rivers. Thus, the concentrations of dissolved organic carbon (DOC), particulate organic carbon (POC), particulate nitrogen (PN), and Chlorophyll‐a (Chl‐a) were measured monthly during 2 hydrological years in the Maroni and Oyapock Rivers to assess the dynamics and fluxes of organic carbon and nitrogen in these 2 Guiana Shield basins, which have been strongly (Maroni) and weakly (Oyapock) impacted by deforestation and mining activities. The 2‐year time series show that DOC, POC, PN, and Chl‐a concentrations vary seasonally with discharge in both rivers, indicating a hydrologically dominated control. Temporal patterns of DOC, POC, and PN indicate that these variables show maximum concentrations in rising waters due to the yield of organic matter and nitrogen accumulated in soils, which are incorporated into the rivers during rainfall. However, the Chl‐a concentrations were at a maximum during low‐water stages. The C/N and C/Chl‐a ratios also showed a seasonal trend, with lower values during the low water periods due to an increase in algal biomass. During high water, the POC in both rivers is the result of terrestrial organic matter, whereas during low‐water autochthonous organic matter can reach up to 34% of the POC. The mean annual fluxes of TOC and PN were higher (4.56 × 10⁵ tonC year^?1 and 1.77 × 10⁴ tonN year^?1, respectively) in the Maroni River than those (1.84 × 10⁵ tonC year^?1 and 0.54 × 10⁴ tonN year^?1, respectively) in the Oyapock River. However, the specific fluxes of DOC, POC, and PN from both basins were nearly the same. Although gold mining activities are performed in both basins, there is no conclusive evidence regarding the impact of these activities on the dynamics of organic matter and particulate nitrogen in the Maroni and Oyapock Rivers.  相似文献   

The influence of geological, geochemical, and biogenic habitat heterogeneity on seep biodiversity     

Erik E. Cordes  Marina R. Cunha  Joëlle Galéron  Camilo Mora  Karine Olu-Le Roy  Myriam Sibuet  Saskia Van Gaever  Ann Vanreusel  & Lisa A. Levin 《Marine Ecology》2010,31(1):51-65

Cold seeps are among the most heterogeneous of all continental margin habitats. Abiotic sources of heterogeneity in these systems include local variability in fluid flow, geochemistry, and substrate type, which give rise to different sets of microbial communities, microbial symbiont-bearing foundation species, and associated heterotrophic species. Biogenic habitats created by microbial mats and the symbiotic species including vesicomyid clams, bathymodiolin mussels, and siboglinid tubeworms add an additional layer of complexity to seep habitats. These forms of habitat heterogeneity result in a variety of macrofaunal and meiofaunal communities that respond to changes in structural complexity, habitat geochemistry, nutrient sources, and interspecific interactions in different ways and at different scales. These responses are predicted by a set of theoretical metacommunity models, the most appropriate of which for seep systems appears to be the 'species sorting' concept, an extension of niche theory. This concept is demonstrated through predictable patterns of community assembly, succession, and beta-level diversity. These processes are described using a newly developed analytical technique examining the change in the slope of the species accumulation curve with the number of habitats examined. The diversity response to heterogeneity has a consistent form, but quantitatively changes at different seep sites around the world as the types of habitats present and the size-classes of fauna analyzed change. The increase in beta diversity across seep habitat types demonstrates that cold seeps and associated biogenic habitats are significant sources of heterogeneity on continental margins globally.  相似文献   

Tributyl tin levels for sea water,sediment, and selected marine species in coastal Northland and Auckland,New Zealand     

Nick King  Michael Miller  Steve de Mora 《新西兰海洋与淡水研究杂志》2013,47(2):287-294

Water and sediment samples were collected from the Waitemata Harbour, Opua Inlet, and Tutukaka Harbour, and analysed for tributyl tin (TBT) using a hydride generation atomic absorption method. Specimens of oysters (Crassostrea gigas, Saccostrea glomerata, Ostrea heffordi) and oyster borer, Lepsiella scobina, were collected from the Tamaki Estuary and surrounding areas. These specimens were analysed for TBT using graphite furnace atomic absorption, and the oyster shell valves were examined for thickening. Concentrations of TBT in the water column were as high as 0.32 μg TBT‐Sn H. Marina sediments contained up to 0.240 μg TBT‐Sn g^‐1. Shell thickening was found to occur in C. gigas where its incidence was correlated with the TBT body burden. Concentrations up to 2.24 μg TBT‐Sn gr^‐1 (on a dry weight basis) were observed for C. gigas. This survey provides evidence for the toxic influence of TBT on non‐target organisms in New Zealand.  相似文献   

Chrono‐stratigraphy of the Upper Pleistocene and Holocene archaeological sequence in Cova Gran (south‐eastern Pre‐Pyrenees,Iberian Peninsula)     

R. Mora  A. Benito‐Calvo  J. Martínez‐Moreno  P. González Marcen  I. De La Torre 《第四纪科学杂志》2011,26(6):635-644

The Cova Gran de Santa Linya (Lleida, Spain) is a recently discovered site, with a broad chrono‐cultural sequence that contains archaeological levels dating to the Middle Palaeolithic, Early Upper Palaeolithic, Late Upper Palaeolithic, Neolithic and Early Bronze Age. We present the chronometric and stratigraphic context of these occupations, which were dated using ¹⁴C accelerator mass spectrometry and thermoluminescence. The sequence provides important indicators that aid in the reconstruction of the history of human occupation on the southern slopes of the Spanish Pyrenees over the past 50,000 years. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Megafan formation driven by explosive volcanism and active tectonic processes in a humid tropical environment          下载免费PDF全文

Jorge P. Galve  Guillermo E. Alvarado  José Vicente Pérez‐Peña  Mauricio M. Mora  Guillermo Booth‐Rea  José Miguel Azañón 《地学学报》2016,28(6):427-433

Quaternary volcanism in the Central Cordillera of Costa Rica has created an orographic barrier that concentrates rainfall on its northern side. This humid climate produces weathered bedrock prone to landsliding. Ash fall from explosive eruptions kills the vegetation cover and intensifies erosion processes. These eruptions, hydrothermal activity and associated earthquakes destabilize the slopes of river valleys, and even the volcanic edifices, producing landslides and large debris avalanches. All these processes mobilize an extra sediment input that is deposited in the piedmont lowlands forming the Santa Clara megafan. The megafans described in the literature mainly grow according to climatic fluctuations; however, sedimentation in the Santa Clara megafan is also controlled by endogenic processes with longer recurrence periods. Analysis of this megafan provides new insight into the origin and evolution of these landforms. In volcanic regions, active volcanism should be considered when investigating the formation of some megafans.  相似文献   

Application of evidential reasoning to improve the mapping of regenerating forest stands     

Brice Mora  Richard A. Fournier  Samuel Foucher 《International Journal of Applied Earth Observation and Geoinformation》2011

This study confirmed the ability of the Dempster–Shafer theory (DST) and the Dezert–Smarandache (Free DSm model) theory to significantly improve the quality of maps of regenerating forest stands in southern Quebec, Canada compared to a classical Maximum Likelihood Algorithm (MLA). The proposed approach uses data fusion methods that allow the integration of remotely sensed imagery with conventional maps of ecophysiographic features. While the MLA provided an overall accuracy of 82.75%, the DST and Free DSm models had overall accuracies of 90.14% and 91.13% respectively. In addition, this study showed that the data fusion methods can model the influence of biophysical parameters (e.g., surface deposits and drainage) on the growth potential of regenerating forest stands. This study illustrates the importance of the mass function allocation for each ancillary data source. We found that a Bayesian belief configuration provided results equivalent to those obtained when representing data uncertainty. This demonstrates the difficulty in modelling uncertainty associated with each ancillary source.  相似文献   

Aliphatic and aromatic hydrocarbons in coastal Caspian Sea sediments   总被引：17，自引：0，他引：17  

Tolosa I  de Mora S  Sheikholeslami MR  Villeneuve JP  Bartocci J  Cattini C 《Marine pollution bulletin》2004,48(1-2):44-60

This investigation represents the first extensive study of the spatial distribution and sources of aliphatic (n-alkanes and unresolved complex mixture of fossil hydrocarbons) and polycyclic aromatic hydrocarbons (PAHs) in coastal sediments from the Caspian Sea. PAH concentrations, n-alkanes and biomarker profiles all suggested that there was limited petrogenic contamination in the shallow North Caspian Sea sediments, which are coarse with a low total organic carbon content. In contrast, moderate to high petrogenic contamination was found in the South Caspian Sea, in particular in the offshore oil fields near Baku, Azerbaijan. Contaminant patterns indicated that the PAHs were mainly from fossil sources, with higher contributions of pyrolytic only near industrialized and urban areas. A high contribution of perylene, a geochemically derived PAH, to the total PAHs was found in the west and south at sites influenced by the Kura, Safid Rud, Terek, Sulak and Samur Rivers.  相似文献   

Arecibo timing and single-pulse observations of 17 pulsars   总被引：1，自引：0，他引：1  

D. J. Champion  D. R. Lorimer  M. A. McLaughlin  K. M. Xilouris  Z. Arzoumanian  P. C. C. Freire  A. N. Lommen  J. M. Cordes  F. Camilo 《Monthly notices of the Royal Astronomical Society》2005,363(3):929-936

We have analysed the soft X-ray emission in a wide area of the Sculptor supercluster by using overlapping ROSAT Position Sensitive Proportional Counter pointings. After subtraction of the point sources, we have found evidence for extended, diffuse soft X-ray emission. We have investigated the nature of such extended emission through the cross-correlation with the density of galaxies as inferred from the Münster Redshift Survey. In particular, we have analysed the correlation as a function of the temperature of the X-ray emitting gas. We have found a significant correlation of the galaxy distribution only with the softest X-ray emission (0.1 – 0.3 keV) and only for gas temperatures   kT < 0.5 keV  . We have excluded the fact that this soft X-ray diffuse emission, and its correlation with the galaxy distribution, is significantly contributed by unresolved active galactic nuclei, groups of galaxies or individual galaxies. The most likely explanation is that the soft, diffuse X-ray emission is tracing warm–hot intergalactic medium, with temperatures below 0.5 keV, associated with the large-scale structures in the Sculptor supercluster.  相似文献   

The Parkes Multibeam Pulsar Survey – III. Young pulsars and the discovery and timing of 200 pulsars     

M. Kramer  J. F. Bell  R. N. Manchester  A. G. Lyne  F. Camilo  I. H. Stairs  N. D'Amico  V. M. Kaspi  G. Hobbs  D. J. Morris  F. Crawford  A. Possenti  B. C. Joshi  M. A. McLaughlin  D. R. Lorimer  A. J. Faulkner 《Monthly notices of the Royal Astronomical Society》2003,342(4):1299-1324

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