نتایج جستجو برای: radiocarbon dating

تعداد نتایج: 18604  

2000

In cellular communications there are two primary communication links between the cell’s central basestation and the users, the uplink (or reverse link) and the downlink (or forward link). The former refers to the flow of information from the users to the basestation, and is a problem which has been and is still today the subject of much debate. The downlink, however, receives less attention, si...

2007
C. J. Colbourn K. W. Yates S. Zhao Warren Yates Sufang Zhao

| Code division multiplexing or multiple access techniques provide a method of isolating multiuser transmissions in a non-orthogonal fashion. The communication resources are shared dynamically between users. In networks with bursty traac having a large numbers of subscribers, each having very low duty cycles, non-orthogonal channeliza-tion enables active users to exploit the shared portion of s...

2017
Fiona Brock Gordon T Cook

Radiocarbon dating is a valuable tool for the forensic examination of human remains in answering questions as to whether the remains are of forensic or medico-legal interest or archaeological in date. The technique is also potentially capable of providing the year of birth and/or death of an individual. Atmospheric radiocarbon levels are currently enhanced relative to the natural level due to t...

Journal: :Tree physiology 2007
Adrian Patrut Karl F von Reden Daniel A Lowy Andries H Alberts John W Pohlman Rudolf Wittmann Dana Gerlach Li Xu Clark S Mitchell

In late 2004, Grootboom, probably the largest known African baobab (Adansonia digitata L.), collapsed unexpectedly in northeastern Namibia. Ten wood samples collected from different areas of the trunk were processed and investigated by accelerator mass spectrometry radiocarbon dating. The radiocarbon dates of three samples were greater than 1000 years BP (radiocarbon years before present, i.e.,...

2013
J. Boex C. Fogwill S. Harrison N. F. Glasser A. Hein C. Schnabel S. Xu

Here we present the first reconstruction of vertical ice-sheet profile changes from any of the Southern Hemisphere's mid-latitude Pleistocene ice sheets. We use cosmogenic radio-nuclide (CRN) exposure analysis to record the decay of the former Patagonian Ice Sheet (PIS) from the Last Glacial Maximum (LGM) and into the late glacial. Our samples, from mountains along an east-west transect to the ...

2006
R. Paladino

Aims. We present new radio continuum observations of ten BIMA SONG galaxies, taken at 1.4 GHz with the Very Large Array. These observations allow us to extend the study of the relationships between the radio continuum (RC) and CO emission to 22 CO luminous galaxies for which single dish CO images have been added to interferometric data. New Spitzer infrared (IR) images of six of these galaxies ...

2017
Mathias Harzhauser Gudrun Daxner-Höck Margarita A. Erbajeva Paloma López-Guerrero Olivier Maridet Adriana Oliver Werner E. Piller Ursula B. Göhlich Reinhard Ziegler

The Taatsiin Gol Basin in Mongolia is a key area for understanding the evolution and dispersal of Central Asian mammal faunas during the Oligocene and early Miocene. After two decades of intense fieldwork, the area is extraordinarily well sampled and taxonomically well studied, yielding a large dataset of 19,042 specimens from 60 samples. The specimens represent 176 species-level and 99 genus-l...

2003
P. W. G. TANNER J. A. EVANS

There has been controversy over the number and timing of orogenies in the Precambrian Moine block in the Scottish Caledonides since the earliest radiometric dating in the 1960s. This work challenges a recent hypothesis, that this sector of the Laurentian margin was subjected to continuous crustal extension between .900 and 470 Ma. U–Pb dating (thermal ionization mass spectrometry) of titanite f...

2005
R. E. TAYLOR

Radiocarbon (I4C) dating, now in its fifth decade of general use, continues to be the most widely employed method of inferring chronometric age for late Pleistocene and Holocene age materials recovered from archeological contexts. Over the last decade, several technical advances in I4C studies have provided contexts for a number of significant applications in archeology that were previously eit...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2017
Jean-Jacques Hublin

The mechanism of the Neanderthal extinction and their replacement by modern humans of African origin is one of the most discussed issues in paleoanthropology. Central to this discussion are the questions of the chronological overlap between Neanderthal populations and modern humans in Western Eurasia and the precise geographical circumstances of this overlap. For a long time, the Vindija (Croat...

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