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Climatic change that affects biological productivity is often argued to be a primary force influencing human activities during the glacial period. To test this assumption, we combine in-site pollen, paleoclimatic, and archaeological data from the Dadiwan site and nearby areas on the western Loess Plateau (WLP) that date to Marine Oxygen Isotope Stage (MIS) 3. Our comparison of multiple datasets suggests that regional human activities increased when the vegetation around the Dadiwan area shifted from forest steppe in the early MIS 3 (59–46.7 ka) to steppe in the middle to late MIS 3 (46.7–29.5 ka). Our results indicate that regional human activities increased again during the late MIS 3 when the amount of precipitation was higher, as indicated by the lower Artemisia proportion. We suggest that increased precipitation on the WLP enhanced the above-ground biomass production and may be responsible for an increase in human activity and population in this region.
In north-central China, subsistence practices transitioned from hunting and gathering to millet-based agriculture between the early and middle Holocene. To better understand how ancient environmental changes influenced this shift in subsistence strategies and human activities at regional to local levels, we conducted palynological and lithologic analyses on radiocarbon-dated sediment cores from the Luoyang Basin, western Henan Province. Our palynological results suggest that vegetation shifted from broad-leaved deciduous forest (9230–8850 cal yr BP) to steppe-meadow vegetation (8850–7550 cal yr BP), and then to steppe with sparse trees (7550–6920 cal yr BP). Lithologic analyses also indicate that the stabilization of the Luoyang Basin’s floodplain after ~8370 cal yr BP might have attracted people to move into the basin, promoting the emergence of millet-based agriculture during the Peiligang culture period (8500–7000 cal yr BP). Once agricultural practices emerged, the climatic optimum after ~7550 cal yr BP likely facilitated the expansion of the Yangshao culture (7000–5000 cal yr BP) in north-central China. As agriculture intensified, pollen taxa related to human disturbance, such as Urtica, increased in abundance.
The ciliate Euplotes encysticus Yonezawa, 1985 was insufficiently described so far regarding its living morphology, infraciliature and silverline system. Recently, a China population was isolated from brackish water (salinity 6‰) near a coastal sandy beach (114°32′E 22°43′N) of the Daya Bay, South China Sea and subsequent investigations were performed on it in detail. Based on data available, the morphology of this species was summarized and a new diagnosis is given which is characterized by: medium-sized body with consistently 9 frontoventral, 2 caudal and 2 left marginal cirri; 30–40 adoral membranelles; 7 dorsal kineties; dorsal silverline system consisting of complex type with irregular network; capable of encystment. Both the morphology and SSr RNA gene sequence show, with high support, a close relationship of E. encysticus and Euplotes muscorum.
We propose to build up a facility of sub-picosecond hard X-ray pulses
based on Thomson scattering between femtosecond laser pulses and
relativistic electrons which is a useful tool for the purpose of
material investigation, plasma diagnostics, and shock wave measurement.
This article reviews the principles and the development of X-ray
sources based on Thomson scattering. Then New Light
Source®, the Thomson scattering X-ray facility we will develop
is introduced. The characteristics of a Thomson scattering X-ray source
are analyzed. A computer model of the Thomson source to be developed is
described in order to provide a source of the rays used in a ray
tracing method, which has proved to be an essential computer tool for
designing and optimizing the optical system of high brightness X-ray
facilities. A code for the ray tracing source model is created based on
the Monte Carlo approach. It is able to evaluate the properties and
performances of the light source under development using this model.
According to the simulation results, we discuss the dependence of
imaging quality and source properties including spectral distribution,
emittance, flux which depends on the laser and electron beam
parameters, in order to check if operation performances are as
expected. We also estimate the possibility of measuring the energy
spectrum of a Thomson scattering source by using a crystal diffraction
method. Ray tracing calculations are performed using SHADOW program
package, and a new model of Thomson scattering X-ray source which can
be processed in that program is established with additional code.
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