分类： 天文学 >> 星系和宇宙学 提交时间： 2023-05-24
摘要： We analyse H(z) parameter data with some conditions by using Lagrange mean value theorem in Calculus. We find that: (1) there exists at least one decelerated phase at 1 $ sigma$ confidence level in the redshift range (0.38, 0.59); (2) the equation of motion of dark energy may be less than -1 at 1 confidence level at some redshifts in the redshift range (1.3, 1.53); (3) there exists at least one accelerated phase at 1 confidence level in the redshift range (1.037, 1.944). These results may provide possible evidences for physics beyond $ Lambd ACDM.
分类： 生物学 >> 动物学 提交时间： 2023-03-14 合作期刊: 《古脊椎动物学报》
摘要： The zygodont proboscideans from the Miocene strata of China are widely distributed. However, the materials are scarce, and their classification has experienced a longtime controversy, from the chaotic state of multiple Zygolophodon species to the only one species, Zygolophodon gobiensis. The combined species Z. gobiensis comprises both the gracile type with a high degree of zygodonty and the robust type that is between the typical bunodont and zygodont morphology. Recently, as the robust type has been re-allocated to another genus Miomastodon and new fossil remains were discovered, it is necessary to further evaluate and classify the zygodont proboscideans from the Miocene of China. In the present paper, we restudied the previously published zygodont specimens of the gracile type, as well as several unpublished Mammutidae specimens. The former including Z. nemonguensis, Z. gromovae, Z. jiningensis, Z. chinjiensis and two specimens of Gomphotherium xiaolongtanensis, represents Zygolophodon in the original sense in China. In these specimens, the tip of the loph(ids) are sharp. The anterior and posterior pretrite central conules are absent or very weak, and the anterior and posterior crescentoids are sharp and slender. The posttrite mesoconelets are well subdivided and the zygodont crests are developed. In buccal view, the loph(id)s are Ʌ-shaped and the interloph(id) s are V-shaped. Their molar morphology resembles that of Z. turicensis, and hereby, they were identified as Zygolophodon cf. Z. turicensis. Several unpublished specimens from Hezheng, Gansu, Tunggur, Nei Mongol, Tongxin, Ningxia and Junggar, Xinjiang exhibit a lower degree of zygodonty, corresponding to the robust type of Zygolophodon in which the molar morphology is between the typical bunodonts and zygodonts. The pretrite crescentoids are thicker than Zygolophodon cf. Z. turicensis, and the pretrite central conules usually present on the first and second interloph(id)s. According to the stratigraphic age and characteristics, two species, Miomastodon gobiensis and Mio. tongxinensis were identified. The anterior and posterior pretrite crescentoids of Mio. tongxinensis are weaker and the pretrite central conules are larger than Mio.gobiensis. Geographical distribution indicates that Miomastodon is the predominant member of zygolophodonts in the Early and Middle Miocene in northern China. The discovery of new materials and the reclassification of zygolophodonts provide further evidence for dispersal of Mammutidae from Eurasia to North America and the evolutionary relationships among the species of the family Mammutidae in China.
分类： 物理学 >> 核物理学 提交时间： 2016-09-14
Wang Xiao-Zhuang
Heng Yue-Kun
Wu Zhi
Li Cheng
Sun Yong-Jie
Dai Hong-Liang
Sun Sheng-Sen
Yang Rong-Xing
Cao Ping
Zhang Jie
Wang Yun
Sun Wei-Jia
Wang Si-Yu
Ji Xiao-Lu
Zhao Jin-Zhou
Gong Wen-Xuan
Ye Mei
Ma Xiao-Yan
Chen Ming-Ming
Xu Mei-hang
摘要： In order to improve the particle identification capability of the Beijing Spectrometer III (BESIII),t is proposed to upgrade the current endcap time-of-flight (ETOF) detector with multi-gap resistive plate chamber (MRPC) technology. Aiming at extending ETOF overall time resolution better than 100ps, the whole system including MRPC detectors, new-designed Front End Electronics (FEE), CLOCK module, fast control boards and time to digital modules (TDIG), was built up and operated online 3 months under the cosmic ray. The main purposes of cosmic ray test are checking the detectors' construction quality, testing the joint operation of all instruments and guaranteeing the performance of the system. The results imply MRPC time resolution better than 100ps, efficiency is about 98%燼nd the noise rate of strip is lower than 1Hz/(scm2) at normal threshold range, the details are discussed and analyzed specifically in this paper. The test indicates that the whole ETOF system would work well and satisfy the requirements of upgrade.
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