抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Additional co-authors: TJ Heaton, AG Hogg, KA Hughen, KF Kaiser, B Kromer, SW Manning, RW Reimer, DA Richards, JR Southon, S Talamo, CSM Turney, J van der Plicht, CE Weyhenmeyer

/pdf/intcal13-and-marine13-radiocarbon-age-calibration-curves-0-4f3vsbzfqx.pdf

IntCal13 and Marine13 radiocarbon age calibration curves 0-50,000 years cal BP

The recent completion of drilling at Vostok station in East Antarctica has allowed the extension of the ice record of atmospheric composition and climate to the past four glacial–interglacial cycles. The succession of changes through each climate cycle and termination was similar, and atmospheric and climate properties oscillated between stable bounds. Interglacial periods differed in temporal evolution and duration. Atmospheric concentrations of carbon dioxide and methane correlate well with Antarctic air-temperature throughout the record. Present-day atmospheric burdens of these two important greenhouse gases seem to have been unprecedented during the past 420,000 years.

Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica

/pdf/climate-and-atmospheric-history-of-the-past-420-000-years-2jdtde1xna.pdf

Surface winds and surface ocean hydrography in the subpolar North Atlantic appear to have been influenced by variations in solar output through the entire Holocene. The evidence comes from a close correlation between inferred changes in production rates of the cosmogenic nuclides carbon-14 and beryllium-10 and centennial to millennial time scale changes in proxies of drift ice measured in deep-sea sediment cores. A solar forcing mechanism therefore may underlie at least the Holocene segment of the North Atlantic's "1500-year" cycle. The surface hydrographic changes may have affected production of North Atlantic Deep Water, potentially providing an additional mechanism for amplifying the solar signals and transmitting them globally.

http://science.sciencemag.org/content/sci/294/5549/2130.full.pdf

Persistent Solar Influence on North Atlantic Climate During the Holocene

Distributions of 10Be in vein quartz from a lateritic weathering profile from the Congo provide evidence for significant in situ production of 10Be by reactions other than neutron-induced spallation. After consideration of geomorphological and nuclear processes which might contribute to the observed depth variability, we conclude that cosmic ray muon-induced reactions are the most likely mechanism, and that such reactions lead to 1% to 3% of 10Be production at the surface. This small muon-induced component has only minor implications for the use of 10Be for quantification of exposure histories of surficial rocks. Nevertheless, the muogenic component has the potential to expand the utility of cosmogenic nuclides in examination of surficial processes, overcoming some of the limitations associated with the use of the neutron-produced component.

Evidence for muon‐induced production of 10Be in near‐surface rocks from the Congo

The possibility that ice-free areas existed during the late Weichselian glaciation of the Svalbard archipelago has been debated for several decades. This study reveals the first geologic evidence that nunataks existed on the islands of northwest Svalbard. Several 10 Be exposure ages were obtained from bedrock and glacial erratics on Danskoya and Amsterdamoya Islands. Exposure ages for glacial erratics laid down in block-field‐covered plateaus .300 m above sea level show that the last ice sheet that completely covered the islands deglaciated .80 k.y. ago. Dating of marine sediments close to sea level reveals that full ice-free conditions were achieved by ca. 50 ka. During the late Weichselian, the coastal lowlands were glaciated, and the major fjords and troughs controlled glacier flow. The existence of nunataks at this time opens the possibility for glacial survival of plant species.

/pdf/northwest-svalbard-during-the-last-glaciation-ice-free-areas-1wbzyfqzyv.pdf

Northwest Svalbard during the last glaciation: Ice-free areas existed

https://ir.library.oregonstate.edu/downloads/df65vd037

Beryllium-10 exposure ages of erratic boulders in southern Norway and implications for the history of the Fennoscandian Ice Sheet

Reversals in the geomagnetic field, which occur every few hundred thousand years, represent a dramatic change in the Earth's environment. Although there is no satisfactory theory for such reversals, it is generally accepted that the dipole field intensity decreases to <20% of its ‘normal’ value for a few thousand years during the change in direction1. Because the galactic and solar cosmic rays which impinge on the Earth's atmosphere are charged, a significant fraction (about half) of them are deflected by the geomagnetic field2. At the time of a reversal, this magnetic shielding is greatly reduced, and it has been suggested that the increased flux of high-energy particles could have effects on evolutionary3 or climatic4 processes. For example, the statistically significant coincidence in levels of some marine faunal extinctions and reversal boundaries in ocean sediments5 could be caused, directly or indirectly, by the decreased geomagnetic intensity during the reversal. We report here evidence in marine sediments for an increase in cosmogenic 10Be production in the Earth's atmosphere during the Brunhes–Matuyama reversal 730,000 yr ago. In addition to confirming an increase in cosmogenic isotope production, the results provide information on the magnitude and duration of the geomagnetic intensity decrease during such an event, and the depth at which rmanent magnetism is acquired in marine sediments.

/pdf/evidence-for-an-increase-in-cosmogenic-10be-during-a-5ftvkec56j.pdf

Evidence for an increase in cosmogenic 10Be during a geomagnetic reversal

The present status for measuring 10Be and 26Al at the Gif-sur-Yvette Tandetron AMS facility is reviewed. We conclude that the capabilities for these two isotopes (especially 10Be) are competitive with those currently obtained at higher energy accelerators.

Grant M. Raisbeck

Papers

Evidence for muon‐induced production of 10Be in near‐surface rocks from the Congo

Northwest Svalbard during the last glaciation: Ice-free areas existed

Beryllium-10 exposure ages of erratic boulders in southern Norway and implications for the history of the Fennoscandian Ice Sheet

Evidence for an increase in cosmogenic 10Be during a geomagnetic reversal

Measurements of 10Be and 26Al with a tandetron AMS facility