Projected seasonal mean summer monsoon over India and adjoining regions for the twenty-first century     

Sushil K. Dash  Saroj K. Mishra  Kanhu C. Pattnayak  Ashu Mamgain  Laura Mariotti  Erika Coppola  Filippo Giorgi  Graziano Giuliani 《Theoretical and Applied Climatology》2015,122(3-4):581-593

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光纤光学延迟线及其应用于望远镜干涉阵的可行性研究     

赵培谦  周必方 《天文学报》1995,36(1):86-92,T001

本文叙述了一台全新的全光学干涉仪，以此干涉仪为基础，就光纤联接的望远镜干涉阵中用拉伸光纤实现光程补偿的方法在国际上首次进行了研究，在对试验结果进行分析，讨论的基础上肯定了该方法的可行性。  相似文献   

Using the photons from the Crab Nebula seen by GLAST to calibrate MAGIC and the imaging air Cherenkov telescopes     

D. Bastieri  C. Bigongiari  E. Bisesi  G. Busetto  A. De Angelis  B. De Lotto  T. Lenisa  F. Longo  M. Mariotti  A. Moralejo  D. Pascoli  L. Peruzzo  R. Rando  A. Saggion  P. Sartori  V. Scalzotto 《Astroparticle Physics》2005,23(6):572-576

In this article we discuss the possibility of using the observations by GLAST of standard gamma sources, as the Crab Nebula, to calibrate imaging air Cherenkov detectors, MAGIC in particular, and optimise their energy resolution. We show that at around 100 GeV the absolute energy calibration uncertainty of Cherenkov telescopes can be reduced to 10% by means of such cross-calibration procedure.  相似文献   

Tropical influence on Euro-Asian autumn rainfall variability   总被引：2，自引：1，他引：2  

A. Mariotti  J. Ballabrera-Poy  N. Zeng 《Climate Dynamics》2005,24(5):511-521

The connection between autumn rainfall variability in the Euro-Asian domain and tropical climate is documented using state-of-the-art global observational datasets and re-analyses. Results suggest a robust statistical relationship between the El Niño Southern Oscillation (ENSO) and autumn rainfall in parts of southwest Europe, northern Africa and southwest Asia. The correlation between area-mean anomalies over this region (P_ea) and the NIÑO3.4 index is 0.68, stationary over the last 50 years. Global ENSO-like tropical climate anomalies are observed in conjunction with P_ea anomalies confirming the relationship found with the NIÑO3.4 index. Overall, the connection with Indo-Pacific variability is stronger than that with the eastern Pacific.While rainfall anomalies in southwest Europe and southwest Asia appear to largely co-vary as one pattern under the influence of ENSO, our results suggest that different mechanisms may be contributing to the observed anomalies. In the North Atlantic/European region, it is speculated that while a PNA-like mode maybe the prevailing teleconnection mechanism for high P_ea, for low P_ea tropical Atlantic ENSO related SST anomalies may be playing a more relevant role forcing northeastward propagating Rossby waves. Over southwest Asia, a more direct connection to the Indo-Pacific region is suggested by the upper air anomaly observed over southern Asia, possibly the Rossby wave response to enhanced heating in the Indian Ocean.  相似文献   

Paleobiological Implications of the Isotopic Signatures (C,N) of Fossil Mammal Collagen in Scladina Cave (Sclayn, Belgium)     

Hervé Bocherens  Daniel Billiou  Marylène Patou-Mathis  Dominique Bonjean  Marcel Otte  André Mariotti 《Quaternary Research》1997,48(3):370-380

An isotopic investigation of upper Pleistocene mammal bones and teeth from Scladina cave (Sclayn, Belgium) demonstrated the very good quality of collagen preservation. A preliminary screening of the samples used the amount of nitrogen in whole bone and dentine in order to estimate the preserved amount of collagen before starting the extraction process. The isotopic abundances of fossil specimens from still-extant species are consistent with their trophic position. Moreover, the¹⁵N isotopic abundance is higher in dentine than in bone in bears and hyenas, a phenomenon already observed in modern specimens. These results demonstrate that the isotopic compositions of samples from Scladina cave can be interpreted in ecological terms. Mammoths exhibit a high¹⁵N isotopic abundance relative to other herbivores, as was the case in Siberian and Alaskan samples. These results suggest distinctive dietary adaptations in herbivores living in the mammoth steppe. Cave bears are clearly isotopically different from coeval brown bears, suggesting an ecological separation between species, with a pure vegetarian diet for cave bear and an omnivorous diet for brown bear.  相似文献   

A high temperature superconductor notch filter for the Sardinia Radio Telescope     

Pietro Bolli  Luca Cresci  Frederick Huang  Sergio Mariotti  Dario Panella 《Experimental Astronomy》2018,45(2):165-176

A High Temperature Superconductor filter operating in the C-band between 4200 and 5600 MHz has been developed for one of the radio astronomical receivers of the Sardinia Radio Telescope. The motivation was to attenuate an interference from a weather radar at 5640 MHz, whose power level exceeds the linear region of the first active stages of the receiver. A very sharp transition after the nominal maximum passband frequency is reached by combining a 6th order band-pass filter with a 6th order stop-band. This solution is competitive with an alternative layout based on a cascaded triplet filter. Three units of the filter have been measured with two different calibration approaches to investigate pros and cons of each, and data repeatability. The final performance figures of the filters are: ohmic losses of the order of 0.15–0.25 dB, matching better than ?15 dB, and ?30 dB attenuation at 5640 MHz. Finally, a more accurate model of the connection between external connector and microstrip shows a better agreement between simulations and experimental data.  相似文献   

The DARWIN project     

A. Léger  J. M. Mariotti  B. Mennesson  M. Ollivier  J. L. Puget  D. Rouan  J. Schneider 《Astrophysics and Space Science》1996,241(1):135-146

Angel and co-workers have proposed to detect exoplanets around nearby stars in the infrared (6–17 m) and to analyze their spectra, searching for H₂O, CO₂, CH₄, NH₃, and O₃ spectral features. The presence or absence of CO₂ would indicate either a strong similarity or difference with Solar telluric planet atmospheres. Water would indicate a habitable planet, and O₃ would reveal significant photosynthesis activity, due to the presence of carbon chemistry based life. Like these authors, we suggest an infrared nulling interferometer pointing to the star and working as a coronograph. Our main contribution is to propose an observatory made of four to five 1-meter class telescopes observing from about 4 to 5 AU to avoid the Solar Zodiacal Light (ZL) background at 10m instead of four 8-meter ones observing from the Earth vicinity. This allows the mission to be feasible in thenear future. The concept, named DARWIN, is under consideration by the European Space Agency for its Horizon 2000 Plus program.  相似文献   

Possible algal origin of long chain odd n-alkanes in immature sediments as revealed by distributions and carbon isotope ratios     

ric Lichtfouse  Sylvie Derenne  Andr Mariotti  Claude Largeau 《Organic Geochemistry》1994,22(6)

A Pliocene oil shale (Pula, Hungary), a C₃ plant Triticum aestivum and a C₄ plant Zea mays were compared using isotopic composition of bulk organic matter, along with distributions and individual carbon isotope ratios of n-alkanes from organic extracts. The microalga Botryococcus braunii (A race) was thus shown to be the main source of the predominant 27, 29 and 31 n-alkanes of Pula sediment Therefore, the dominance of odd carbon-numbered n-alkanes in the range C₂₅–₃₅ in extracts from immature sediments shall not be systematically assigned to higher plant contribution but algal input is also possible. In fact, the long chain n-alkanes with an odd predominance previously observed in extracts of various immature sediments are likely to be derived at least partially, from algae.  相似文献   

Experimentally-controlled carbon and oxygen isotope exchange between bioapatites and water under inorganic and microbially-mediated conditions     

Antoine Zazzo  Christophe Lécuyer  André Mariotti 《Geochimica et cosmochimica acta》2004,68(1):1-12

Modern bone and enamel powders have reacted at 301 K with ¹³C- and ¹⁸O-labelled waters under inorganic and microbial conditions. The aim of the study is to investigate the resistance of stable isotope compositions of bioapatite carbonate (δ¹³C, δ¹⁸Oc) and phosphate (δ¹⁸Op) to isotopic alteration during early diagenesis. Rapid and significant carbon and oxygen isotope changes were observed in the carbonate and phosphate fractions of bone apatite before any detectable change occurred in the crystallinity or organic matter content. These observations indicate that chemical alterations of bone apatite are likely to start within days of death. Enamel crystallites are much more resistant than bone crystallites, but are not exempt of alteration. Non removable carbon and oxygen isotope enrichments were measured in the carbonate phase of bone (50-90%) and enamel (40%) after the acetic acid treatment. This result indicates that a significant part of ¹³C and ¹⁸O-labelled coming from the aqueous fluid has been durably incorporated into the apatite structure, probably through isotopic exchange or secondary carbonate apatite precipitation. As a result, acetic acid pre-treatments that are currently used to remove exogenous material by selective dissolution, are not adequate to restore pristine δ¹³C and δ¹⁸Oc values of fossil apatites. Under inorganic conditions, kinetics of oxygen isotope exchange are 10 times faster in carbonate than in phosphate. On the opposite, during biologically-mediated reactions, the kinetics of oxygen isotope exchange between phosphate and water is, at least, from 2 to 15 times faster than between carbonate and water. Enamel is a more suitable material than bone for paleoenvironmental or paleoclimatical reconstructions, but interpretations of δ¹⁸Op or δ¹³C values must be restricted to specimens for which no or very limited trace of microbial activity can be detected.  相似文献   

Natural isotopic composition of nitrogen as a tracer of origin for suspended organic matter in the Scheldt estuary     

André Mariotti  Christiane Lancelot  Gilles Billen 《Geochimica et cosmochimica acta》1984,48(3):549-555

The natural isotopic composition of suspended particulate organic nitrogen was determined in the Southern Bight of the North Sea and in the Scheldt estuary. These data show that δ¹⁵N constitutes a convenient tracer of the origin of the suspended matter.In the winter, in the absence of intensive primary production, the suspended organic matter of the Scheldt estuary is a mixture of two components: a continental detrital component characterized by a low δ value of 1.5%. and a marine component with a mean δ value of 8%..During the phytoplankton flowering period, lasting from early May to October, intensive primary production occurs throughout the estuary giving rise to a third source of organic matter. This material is characterized by high δ values reflecting the isotopic composition of ammonia, the nitrogenous nutrient assimilated by phytoplankton in the estuary.The nitrification process occuring in the mixing area of the Scheldt estuary leads to higher downstream δ values of ammonia (>20%.) which permits the distinction between estuarine from fresh-water phytoplankton. Simple isotopic budget calculations show that, both in the upstream part and in the downstream part, autochthonous phytoplanktonic material contributes a major part of the total suspended matter in the Scheldt estuary during summer.  相似文献