Palaeoenvironments of early hominins in temperate and Mediterranean Eurasia: new palaeobotanical data from Palaeolithic key-sites and synchronous natural sequences     

Erwan Messager  Vincent Lebreton  Laurent Marquer  Elda Russo-Ermolli  Ronan Orain  Josette Renault-Miskovsky  David Lordkipanidze  Jackie Despriée  Carlo Peretto  Marta Arzarello 《Quaternary Science Reviews》2011,30(11-12):1439-1447

The present study focuses on new palaeobotanical data (pollen, phytoliths and fruits) from three of the oldest Early Palaeolithic sites in Eurasia (Dmanisi in Georgia, Ca’ Belvedere di Monte Poggiolo in Italy and Pont-de-Lavaud in France). The main aim is to examine the ecological factors associated with the first human dispersals out of Africa into Eurasia. The palaeoecological data are discussed with regards to chronology and geographical location of the settlements. The vegetation pattern of each site consists of temperate Eurasian and Mediterranean taxa, subtropical trees being more or less recorded depending on climatic and geographic features. The new palaeobotanical data show that different vegetation structures occurred between the first human dispersal in Caucasus and the later dispersals in western Eurasia. However, in all cases hominins seemed to be adapted to temperate ecosystems. In Caucasus, human occupation took place at 1.7 Ma in a forest-steppe environment, while at ca 1 Ma human populations occupied various settings such as open landscapes or dense forests. These data suggest that during the Early Pleistocene, human populations evolved and dispersed in western Eurasia, gradually increasing their degree of adaptation to diversified environments.  相似文献   

Search for radio pulsations in four anomalous X-ray pulsars and discovery of two new pulsars     

Marta Burgay  Nanda Rea  GianLuca Israel  Andrea Possenti  Luciano Burderi  Tiziana Di Salvo  Nichi D’Amico  Luigi Stella  Elisa Nichelli 《Astrophysics and Space Science》2007,308(1-4):531-534

We have performed deep searches for radio pulsations from four southern anomalous X-ray pulsars (AXPs) to investigate their physical nature in comparison with the rotation powered pulsars. The data were acquired using the Parkes radio telescope with the 1.4 GHz multibeam receiver. No pulsed emission with periodicity matching the X-ray ephemeris have been found in the observed targets down to a limit of ∼0.1 mJy. A blind search has also been performed on all the 13 beams of the multibeam receiver (the central beam being pointed on the target AXP), leading to the serendipitous discovery of two new radio pulsars and to the further detection of 18 pulsars. Also a search for single dispersed pulses has been performed in the aim to detect signals similar to those of the recently discovered rotating radio transients.   相似文献   

Chandra smells a RRAT     

Bryan M. Gaensler  Maura McLaughlin  Stephen Reynolds  Kazik Borkowski  Nanda Rea  Andrea Possenti  Gianluca Israel  Marta Burgay  Fernando Camilo  Shami Chatterjee  Michael Kramer  Andrew Lyne  Ingrid Stairs 《Astrophysics and Space Science》2007,308(1-4):95-99

“Rotating RAdio Transients” (RRATs) are a newly discovered astronomical phenomenon, characterised by occasional brief radio bursts, with average intervals between bursts ranging from minutes to hours. The burst spacings allow identification of periodicities, which fall in the range 0.4 to 7 seconds. The RRATs thus seem to be rotating neutron stars, albeit with properties very different from the rest of the population. We here present the serendipitous detection with the Chandra X-ray Observatory of a bright point-like X-ray source coincident with one of the RRATs. We discuss the temporal and spectral properties of this X-ray emission, consider counterparts in other wavebands, and interpret these results in the context of possible explanations for the RRAT population. B.M.G. acknowledges the support of NASA through LTSA grant NAG5-13023 and of an Alfred P. Sloan Fellowship.  相似文献   

Hydrometeorological dataset (2014–2019) from the high Arctic unglaciated catchment Fuglebekken (Svalbard)     

Tomasz Wawrzyniak  Marta Majerska  Marzena Osuch 《水文研究》2021,35(1):e13974

In this study, a hydrometeorological dataset of unglaciated High Arctic catchment is presented. The time series encompasses air temperature, precipitation, wind speed, relative humidity, and runoff data from 2014 to 2019. Meteorological data come from continuous meteorological monitoring carried out at the Hornsund station located in SW Spitsbergen. Flow in the Fuglebekken stream was measured using a portable flowmeter Nivus PCM-F with Active Doppler sensor. Continuous hydrometeorological monitoring in polar environments is crucial for the understanding processes controlling the water circulation in the catchments. Inter- and intra- annual variability of the provided variables gives an insight into river functioning. The data set is provided in an open-access PANGAEA repository (https://doi.pangaea.de/10.1594/PANGAEA.921921), in three time intervals (6, 12, and 24 hours). It may serve as the input to rainfall-runoff hydrological models, and allows multi-model parameter estimation and validation. It can be used in a variety of research topics, including streamflow projections, and more generally in examining Arctic ecosystems and climate change impact studies.  相似文献   

Markovian characteristics of dry spells over the Iberian Peninsula under present and future conditions using ESCENA ensemble of regional climate models     

Noelia López-Franca  Enrique Sánchez  Teresa Losada  Marta Domínguez  Raquel Romera  Miguel Ángel Gaertner 《Climate Dynamics》2015,45(3-4):661-677

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Last Glacial Maximum and the Gschnitz stadial in the Maritime Alps according to 10Be cosmogenic dating     

Paolo Roberto Federici  Darryl E. Granger  Adriano Ribolini  Matteo Spagnolo  Marta Pappalardo  Andrew J. Cyr 《Boreas: An International Journal of Quaternary Research》2012,41(2):277-291

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Development of mirrors made of chemically tempered glass foils for future X-ray telescopes     

Bianca Salmaso  Marta Civitani  Claudia Brizzolari  Stefano Basso  Mauro Ghigo  Giovanni Pareschi  Daniele Spiga  Laura Proserpio  Yves Suppiger 《Experimental Astronomy》2015,39(3):527-545

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Formation of supermassive black holes     

Marta Volonteri 《Astronomy and Astrophysics Review》2010,18(3):279-315

Evidence shows that massive black holes reside in most local galaxies. Studies have also established a number of relations between the MBH mass and properties of the host galaxy such as bulge mass and velocity dispersion. These results suggest that central MBHs, while much less massive than the host (~0.1%), are linked to the evolution of galactic structure. In hierarchical cosmologies, a single big galaxy today can be traced back to the stage when it was split up in hundreds of smaller components. Did MBH seeds form with the same efficiency in small proto-galaxies, or did their formation had to await the buildup of substantial galaxies with deeper potential wells? I briefly review here some of the physical processes that are conducive to the evolution of the massive black hole population. I will discuss black hole formation processes for ‘seed’ black holes that are likely to place at early cosmic epochs, and possible observational tests of these scenarios.  相似文献   

Can PAHs influence Cu accumulation by salt marsh plants?     

Almeida CM  Mucha AP  Delgado MF  Caçador MI  Bordalo AA  Vasconcelos MT 《Marine environmental research》2008,66(3):311-318

The presence of polycyclic aromatic hydrocarbons (PAHs) may change the mechanisms of metal uptake, thus influencing kinetics and extent of metal phytoextraction. Studies on the subject are scarce, particularly for salt marsh plants. The aim of this work was to investigate the effect of PAHs on the uptake of Cu by Halimione portulacoides, a plant commonly found in salt marshes. Experiments were carried out in the laboratory, either in hydroponics (sediment elutriate) or in sediment soaked in elutriate, which were prepared with sediment and water from a salt marsh of the Cavado river estuary (NW Portugal). Groups of H. portulacoides (grown in a greenhouse) were exposed to those media during six days. Cu(2+) (as Cu(NO(3))(2)), 10(2) and 10(4)mugl(-1), was added to the media as well as 1.6mugl(-1) of the sixteen EPA priority PAHs (0.1mugl(-1) of each PAHs). Cu was assayed in solutions, sediments and different plant tissues before and after experiments. After exposure, photosynthetic efficiency and levels of chlorophylls were also measured, indicating that plant stress indicators were identical in all plants independently of the media to which the plants were exposed. PAHs influenced both the soluble Cu fraction and Cu uptake by plants. The amounts of metal accumulated in both roots and stems were significantly higher when the 10(4)mugl(-1) of Cu enriched elutriate was amended with PAHs. Thus, results suggest that PAHs may modify Cu solubility, the Cu sorption by plants and/or the passive penetration of Cu into the root cells. Therefore, the combined effects of different types of pollutants should be taken in consideration when studying the remediation potential of plants, namely in terms of phytoextraction.  相似文献   

SANARIS Project: A Satellite Network for Natural Risk Monitoring     

Tárraga  Marta  Garcia  Alicia  Ortiz  Ramon  Abella  Rafael  Peña  Javier 《Natural Hazards》2001,23(2-3):417-429

A new satellite communication system specificallydesigned for low-rate data applications has beendeveloped and prototyped. A validation project isproposed to install a pilot network to be operated for6 months. One of the target markets related tovolcanoes, has been selected, so that a group of usersis integrated in the project. A specific applicationfor this market will be developed regarding dataacquisition, processing, storage and dissemination todistant users. The feasibility of using the newsatellite system to provide a new Eutelsat service forlow-rate data applications, will be evaluated from theperformance of the pilot network. The system ofautomatic acquisition, field storage and communicationwith the local control center is already functioning,as well as the circulation of information viaInternet. The development of the application andtransmission via satellite to distant users is stillin an evaluation phase for the volcanoes of Timanfaya(Lanzarote, Canary Island), Vesuvius (Naples) and SeteCidades Caldera (Sao Miguel, Azores Islands).  相似文献