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1. chinaXiv:201711.02563 [pdf]

Implications for Late Miocene diet from Diceros gansuensis: starch granules in tooth calculus

CHEN He; WANG Shi-Qi; TAO Da-Wei; XIA Xiu-Min; CHEN Shan-Qin; WU Yan
分类: 地球科学 >> 地质学

Reconstructing the diet of extinct species is a fundamental goal in vertebrate paleobiology. Dental calculus is the calcium phosphate deposits on teeth, which captures a large number of food particles and contains the food information of ancient animal. It is possible to explore ancient animal dietary and investigate the environmental information from dental calculus. A large number of starch granules were found in dental calculus of Dicros gansuensis excavated from the earliest Late Miocene Guonigou fauna of the Linxia Basin, Gansu Province. It is the first time that starch granules from Late Miocene were found. We classified the ancient starch granules by its morphological characteristics and also analyzed the starch granules of leaves of modern plants around the living environment of D. gansuensis to find modern starch granules and compare them with ancient ones. The results indicate that D. gansuensis may eat not only shrubs leaves, such as the plant from Caprifoliaceae, but also some tree leaves from Juglandaceae (walnut), and maybe some herbs from Ranunculaceae and Polygonaceae. It is consistent with the results of previous morphological studies, and it also provides more information. Our study extends the range of time and object for dental calculus research, and offers more possibilities for research on feeding habits of ancient mammals.

提交时间: 2017-11-24 来自合作期刊:《古脊椎动物学报》 点击量23下载量21 评论 0

2. chinaXiv:201711.02398 [pdf]

International UTC TAI comparison based on BDS PPP

Yulong Ge
分类: 地球科学 >> 地球科学其他学科

The BeiDou navigation satellite system (BDS) developed by China, and provided official service for Asia-pacific region freely since 2012. With development of BDS, BDS-based time transfer has become an important research direction in BDS’s application fields. At present, the main method of BDS-based time transfer is BDS Common View (BDS CV), which can reach nanoseconds magnitude. Hence, we investigate the performance time transfer based on BDS precise point positioning (PPP) toward UTC/TAI compute. In this contribution, we focus on UTC/TAI comparison based on BDS PPP by using developed quad-constellation GNSS software, which called National Time System Center’s (NTSC) Bernese. And a long-term data analysis is presented. The experiments include two parts: (1) The reliability of the software and multi-GNSS products; (2) The performance of the BDS PPP toward International UTC/TAI comparison. The experimental results reveal that the accuracy of NTSC’s Bernese GPS PPP can reach about 0.1 ns relative to BIPM TAI PPP solutions. Compared with BIPM TAI PPP solutions, the accuracy of GPS PPP solutions can achieve about 0.2 ns by using multi-GNSS precise products, such as GBM, COM. For BDS PPP solutions, the solutions of GPS PPP are regarded as reference values. It is demonstrated that the accuracy of time transfer based on BDS PPP can reach better 1 ns toward UTC/TAI comparison for the statistics of 30 days-arc solutions, while 0.1 ns magnitude can be achieved for the statistics of daily solutions due to the influence of the day boundary discontinuity. Moreover, four different processing strategies of BDS PPP which include tropospheric delay fixed, tropospheric delay and coordinates fixed, coordinates fixed, and BDS-only are tested. Results show that the comparable accuracy can be achieved for four processing strategies. Hence, one can conclude that the time transfer based on BDS-only PPP show a good performance toward UTC/TAI computation.

提交时间: 2017-11-14 点击量556下载量305 评论 0

3. chinaXiv:201711.00362 [pdf]

Precipitation changes in the mid-latitudes of the Chinese mainland during 1960–2014

HU Yuling; WANG Shigong; SONG Xuping; WANG Jiaxin
分类: 地球科学 >> 地理学

Based on daily precipitation data from 163 meteorological stations, this study investigated precipitation changes in the mid-latitudes of the Chinese mainland (MCM) during 1960–2014 using the climatic trend coefficient, least-squared regression analysis, and a non-parametric Mann-Kendall test. According to the effects of the East Asian summer monsoon on the MCM and the climatic trend coefficient of annual precipitation during 1960–2014, we divided the MCM into the western MCM and eastern MCM.

提交时间: 2017-11-07 来自合作期刊:《Journal of Arid Land》 点击量188下载量26 评论 0

4. chinaXiv:201711.00363 [pdf]

Chemical characteristics of precipitation and the indicative significance for sand dust events in the northern and southern slopes of Wushaoling Mountain, northwestern China

LI Zongjie; LIU Fei; SONG Yong; SONG Lingling; TIAN Qing; JIA Bing; LI Yongge; MA Jinzhu
分类: 地球科学 >> 地理学

Precipitation chemistry analysis is essential to evaluate the atmospheric environmental quality and identify the sources of atmospheric pollutants. In this study, we collected a total of 480 precipitation samples at 6 sampling sites in the northern and southern slopes of Wushaoling Mountain from May 2013 to July 2014 to analyze the chemical characteristics of precipitation and to identify the main sources of ions in precipitation.

提交时间: 2017-11-07 来自合作期刊:《Journal of Arid Land》 点击量182下载量24 评论 0

5. chinaXiv:201711.00364 [pdf]

Meteorological impacts on evapotranspiration in different climatic zones of Pakistan

Shahzada ADNAN; Kalim ULLAH; Azmat H KHAN; GAO Shouting
分类: 地球科学 >> 地理学

Arid regions are highly vulnerable and sensitive to drought. The crops cultivated in arid zones are at high risk due to the high evapotranspiration and water demands. This study analyzed the changes in seasonal and annual evapotranspiration (ET) during 1951-2016 at 50 meteorological stations located in the extremely arid, arid, and semi-arid zones of Pakistan using the Penman Monteith (PM) method.

提交时间: 2017-11-07 来自合作期刊:《Journal of Arid Land》 点击量178下载量21 评论 0

6. chinaXiv:201711.00365 [pdf]

Multi-decadal variations in glacier flow velocity and the influencing factors of Urumqi Glacier No. 1 in Tianshan Mountains, Northwest China

WANG Puyu; LI Zhongqin; XU Chunhaii; RING Wucheng; ZHOU PingZHANG Hui
分类: 地球科学 >> 地理学

Urumqi Glacier No. 1 is a representative glacier in the inland areas of Central Asia and is the only Chinese reference glacier in the World Glacier Monitoring Service. In this study, we explored multi-decadal variations in the flow velocity of the glacier and the influencing factors based on continuous field observations and path coefficient analysis.

提交时间: 2017-11-07 来自合作期刊:《Journal of Arid Land》 点击量216下载量31 评论 0

7. chinaXiv:201711.00366 [pdf]

Wind tunnel test on the effect of metal net fences on sand flux in a Gobi Desert, China

WANG Tao; QU Jianjun; LING Yuquan; XIE Shengbo; XIAO Jianhua
分类: 地球科学 >> 地理学

The Lanzhou-Xinjiang High-speed Railway runs through an expansive windy area in a Gobi Desert, and sand-blocking fences were built to protect the railway from destruction by wind-blown sand.

提交时间: 2017-11-07 来自合作期刊:《Journal of Arid Land》 点击量206下载量27 评论 0

8. chinaXiv:201711.00367 [pdf]

Impact of land use/cover changes on carbon storage in a river valley in arid areas of Northwest China


分类: 地球科学 >> 地理学

Soil carbon pools could become a CO2 source or sink, depending on the directions of land use/cover changes. A slight change of soil carbon will inevitably affect the atmospheric CO2 concentration and consequently the climate.

提交时间: 2017-11-07 来自合作期刊:《Journal of Arid Land》 点击量178下载量23 评论 0

9. chinaXiv:201711.00368 [pdf]

An experimental study of salt expansion in sodium saline soils under transient conditions

WAN Xusheng; YOU Zhemin; WEN HaiyanWilliam CROSSLEY
分类: 地球科学 >> 地理学

Salt expansion in sulfate saline soils that are wider distributed in northwestern China causes serious infrastructural damages under low-temperature conditions. However, the mechanism of salt expansion under low temperatures is not clear.

提交时间: 2017-11-07 来自合作期刊:《Journal of Arid Land》 点击量188下载量23 评论 0

10. chinaXiv:201711.00369 [pdf]

Spatial-temporal variations in near-surface soil freeze-thaw cycles in the source region of the Yellow River during the period 2002-2011 based on the Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) data

WANG Rui; ZHU Qingke; MA Hao; AI Ning
分类: 地球科学 >> 地理学

Detecting near-surface soil freeze-thaw cycles in high-altitude cold regions is important for understanding the Earth's surface system, but such studies are rare. In this study we detected the spatial-temporal variations in near-surface soil freeze-thaw cycles in the source region of the Yellow River during the period 2002-2011 based on data from the Advanced Microwave Scanning Radiometer for the Earth Observing System

提交时间: 2017-11-07 来自合作期刊:《Journal of Arid Land》 点击量200下载量23 评论 0

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