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The timing and effect of the earliest human arrivals in North America 期刊论文
NATURE, 2020
作者:  Lorena Becerra-Valdivia;  Thomas Higham
收藏  |  浏览/下载:27/0  |  提交时间:2020/08/09

The peopling of the Americas marks a major expansion of humans across the planet. However, questions regarding the timing and mechanisms of this dispersal remain, and the previously accepted model (termed '  Clovis-first'  )-suggesting that the first inhabitants of the Americas were linked with the Clovis tradition, a complex marked by distinctive fluted lithic points(1)-has been effectively refuted. Here we analyse chronometric data from 42 North American and Beringian archaeological sites using a Bayesian age modelling approach, and use the resulting chronological framework to elucidate spatiotemporal patterns of human dispersal. We then integrate these patterns with the available genetic and climatic evidence. The data obtained show that humans were probably present before, during and immediately after the Last Glacial Maximum (about 26.5-19 thousand years ago)(2,3)but that more widespread occupation began during a period of abrupt warming, Greenland Interstadial 1 (about 14.7-12.9 thousand years beforead 2000)(4). We also identify the near-synchronous commencement of Beringian, Clovis and Western Stemmed cultural traditions, and an overlap of each with the last dates for the appearance of 18 now-extinct faunal genera. Our analysis suggests that the widespread expansion of humans through North America was a key factor in the extinction of large terrestrial mammals.


A Bayesian age model suggests that human dispersal to the Americas probably began before the Last Glacial Maximum, overlapping with the last dates of appearance for several faunal genera.


  
Ice retreat in Wilkes Basin of East Antarctica during a warm interglacial 期刊论文
NATURE, 2020, 583 (7817) : 554-+
作者:  T. Blackburn;  G. H. Edwards;  S. Tulaczyk;  M. Scudder;  G. Piccione;  B. Hallet;  N. McLean;  J. C. Zachos;  B. Cheney;  J. T. Babbe
收藏  |  浏览/下载:21/0  |  提交时间:2020/08/09

Uranium isotopes in subglacial precipitates from the Wilkes Basin of the East Antarctic Ice Sheet reveal ice retreat during a warm Pleistocene interglacial period about 400,000 years ago.


Efforts to improve sea level forecasting on a warming planet have focused on determining the temperature, sea level and extent of polar ice sheets during Earth'  s past interglacial warm periods(1-3). About 400,000 years ago, during the interglacial period known as Marine Isotopic Stage 11 (MIS11), the global temperature was 1 to 2 degrees Celsius greater(2)and sea level was 6 to 13 metres higher(1,3). Sea level estimates in excess of about 10 metres, however, have been discounted because these require a contribution from the East Antarctic Ice Sheet(3), which has been argued to have remained stable for millions of years before and includes MIS11(4,5). Here we show how the evolution of(234)U enrichment within the subglacial waters of East Antarctica recorded the ice sheet'  s response to MIS11 warming. Within the Wilkes Basin, subglacial chemical precipitates of opal and calcite record accumulation of(234)U (the product of rock-water contact within an isolated subglacial reservoir) up to 20 times higher than that found in marine waters. The timescales of(234)U enrichment place the inception of this reservoir at MIS11. Informed by the(234)U cycling observed in the Laurentide Ice Sheet, where(234)U accumulated during periods of ice stability(6)and was flushed to global oceans in response to deglaciation(7), we interpret our East Antarctic dataset to represent ice loss within the Wilkes Basin at MIS11. The(234)U accumulation within the Wilkes Basin is also observed in the McMurdo Dry Valleys brines(8-10), indicating(11)that the brine originated beneath the adjacent East Antarctic Ice Sheet. The marine origin of brine salts(10)and bacteria(12)implies that MIS11 ice loss was coupled with marine flooding. Collectively, these data indicate that during one of the warmest Pleistocene interglacials, the ice sheet margin at the Wilkes Basin retreated to near the precipitate location, about 700 kilometres inland from the current position of the ice margin, which-assuming current ice volumes-would have contributed about 3 to 4 metres(13)to global sea levels.


  
Abrupt increase in harvested forest area over Europe after 2015 期刊论文
NATURE, 2020, 583 (7814) : 72-+
作者:  Guido Ceccherini;  Gregory Duveiller;  Giacomo Grassi;  Guido Lemoine;  Valerio Avitabile;  Roberto Pilli;  Alessandro Cescatti
收藏  |  浏览/下载:19/0  |  提交时间:2020/07/06

Fine-scale satellite data are used to quantify forest harvest rates in 26 European countries, finding an increase in harvested forest area of 49% and an increase in biomass loss of 69% between 2011-2015 and 2016-2018.


Forests provide a series of ecosystem services that are crucial to our society. In the European Union (EU), forests account for approximately 38% of the total land surface(1). These forests are important carbon sinks, and their conservation efforts are vital for the EU'  s vision of achieving climate neutrality by 2050(2). However, the increasing demand for forest services and products, driven by the bioeconomy, poses challenges for sustainable forest management. Here we use fine-scale satellite data to observe an increase in the harvested forest area (49 per cent) and an increase in biomass loss (69 per cent) over Europe for the period of 2016-2018 relative to 2011-2015, with large losses occurring on the Iberian Peninsula and in the Nordic and Baltic countries. Satellite imagery further reveals that the average patch size of harvested area increased by 34 per cent across Europe, with potential effects on biodiversity, soil erosion and water regulation. The increase in the rate of forest harvest is the result of the recent expansion of wood markets, as suggested by econometric indicators on forestry, wood-based bioenergy and international trade. If such a high rate of forest harvest continues, the post-2020 EU vision of forest-based climate mitigation may be hampered, and the additional carbon losses from forests would require extra emission reductions in other sectors in order to reach climate neutrality by 2050(3).


  
Asteroid impact, not volcanism, caused the end-Cretaceous dinosaur extinction 期刊论文
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 2020, 117 (29) : 17084-17093
作者:  Chiarenza, Alfio Alessandro;  Farnsworth, Alexander;  Mannion, Philip D.;  Lunt, Daniel J.;  Valdes, Paul J.;  Morgan, Joanna, V;  Allison, Peter A.
收藏  |  浏览/下载:17/0  |  提交时间:2020/07/06
Dinosauria  extinction  end-Cretaceous  Chicxulub  Deccan  
Discovery of widely available abyssal rock patches reveals overlooked habitat type and prompts rethinking deep-sea biodiversity 期刊论文
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 2020, 117 (27) : 15450-15459
作者:  Riehl, Torben;  Woelfl, Anne-Cathrin;  Augustin, Nico;  Devey, Colin W.;  Brandt, Angelika
收藏  |  浏览/下载:11/0  |  提交时间:2020/06/22
hydroacoustics  remote sensing  geobiodiversity  habitat mapping  polymetallic nodules  
How cancer genomics is transforming diagnosis and treatment 期刊论文
NATURE, 2020, 579 (7800) : S10-S11
作者:  Pacheco, Gustavo Gavrel
收藏  |  浏览/下载:15/0  |  提交时间:2020/07/03

Genome sequencing is providing physicians with more data about the causes of cancer and changing the way some forms of the disease are treated.


Genome sequencing is providing physicians with more data about the causes of cancer and changing the way some forms of the disease are treated.


  
Origin of interannual variability in global mean sea level 期刊论文
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 2020, 117 (25) : 13983-13990
作者:  Hamlington, Benjamin D.;  Piecuch, Christopher G.;  Reager, John T.;  Chandanpurkar, Hrishi;  Frederikse, Thomas;  Nerem, R. Steven;  Fasullo, John T.;  Cheon, Se-Hyeon
收藏  |  浏览/下载:6/0  |  提交时间:2020/06/16
sea level  climate variability  global mean sea level  satellite altimetry  
Identification of chondritic krypton and xenon in Yellowstone gases and the timing of terrestrial volatile accretion 期刊论文
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 2020, 117 (25) : 13997-14004
作者:  Broadley, Michael W.;  Barry, Peter H.;  Bekaert, David V.;  Byrne, David J.;  Caracausi, Antonio;  Ballentine, Christopher J.;  Marty, Bernard
收藏  |  浏览/下载:9/0  |  提交时间:2020/06/16
origin of Earth'  s volatiles  accretion  mantle plume  noble gases  Yellowstone  
Global impact of atmospheric arsenic on health risk: 2005 to 2015 期刊论文
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 2020, 117 (25) : 13975-13982
作者:  Zhang, Lei;  Gao, Yang;  Wu, Shiliang;  Zhang, Shaoqing;  Smith, Kirk R.;  Yao, Xiaohong;  Gao, Huiwang
收藏  |  浏览/下载:16/0  |  提交时间:2020/06/16
atmospheric arsenic  GEOS-Chem  cancer risk  noncarcinogenic effect  
OPEN SCIENCE TAKES ON COVID-19 期刊论文
NATURE, 2020, 581 (7806) : 109-110
作者:  Mudelsee, Manfred;  Borngen, Michael;  Tetzlaff, Gerd;  Grunewald, Uwe
收藏  |  浏览/下载:11/0  |  提交时间:2020/07/03

Data sharing, open-source designs for medical equipment, and hobbyists are all being harnessed to combat COVID-19.


Data sharing, open-source designs for medical equipment, and hobbyists are all being harnessed to combat COVID-19.