Practical gigahertz quantum key distribution robust against channel disturbance

Quantum key distribution (QKD) provides an attractive solution for secure communication. However, channel disturbance severely limits its application when a QKD system is transfered from the laboratory to the field. Here, a high-speed Faraday-Sagnac-Michelson QKD system is proposed that can automatically compensate for the channel polarization disturbance, which largely avoids the intermittency limitations of environment mutation. Over a 50-km fiber channel with 30-Hz polarization scrambling, the practicality of this phase-coding QKD system was characterized with an interference fringe visibility of 99:35% over 24 hours, and a stable secure key rate of 306k bits/s over 7 days without active polarization alignment

Highly Cited Canada Articles in Science Citation Index Expanded: A Bibliometric Analysis

The characteristics of the highly cited Canada articles in Science Citation Index Expanded from 1900 to 2011 were revealed. Articles that have been cited at least 100 times since publication to 2011 were assessed regarding their distribution in indexed journals and categories of the Web of Science. The citation lives of the top articles depending on citations in publication year, recent year, and years after publications were investigated for the impact history of articles. A new indicator, Y-index, was successfully applied to evaluate publication characteristics of Canada authors and institutions. University of Toronto was the most productive institution. The top three most productive categories of the Web of Science were biochemistry and molecular biology, multidisciplinary sciences, and neurosciences. Journal of Biological Chemistry and Nature hosted the most highly cited Canada articles. In addition, the Y-index was applied to evaluate the publication character of authors and institutions

Y Chromosomes of 40% Chinese Are Descendants of Three Neolithic Super-grandfathers

Demographic change of human populations is one of the central questions for delving into the past of human beings. To identify major population expansions related to male lineages, we sequenced 78 East Asian Y chromosomes at 3.9 Mbp of the non-recombining region (NRY), discovered >4,000 new SNPs, and identified many new clades. The relative divergence dates can be estimated much more precisely using molecular clock. We found that all the Paleolithic divergences were binary; however, three strong star-like Neolithic expansions at ~6 kya (thousand years ago) (assuming a constant substitution rate of 1e-9/bp/year) indicates that ~40% of modern Chinese are patrilineal descendants of only three super-grandfathers at that time. This observation suggests that the main patrilineal expansion in China occurred in the Neolithic Era and might be related to the development of agriculture.Comment: 29 pages of article text including 1 article figure, 9 pages of SI text, and 2 SI figures. 5 SI tables are in a separate ancillary fil

New Vacuum Solar Telescope and Observations with High Resolution

The New Vacuum Solar Telescope (NVST) is a 1 meter vacuum solar telescope that aims to observe the fine structures on the Sun. The main tasks of NVST are high resolution imaging and spectral observations, including the measurements of solar magnetic field. NVST is the primary ground-based facility of Chinese solar community in this solar cycle. It is located by the Fuxian Lake of southwest China, where the seeing is good enough to perform high resolution observations. In this paper, we first introduce the general conditions of Fuxian Solar Observatory and the primary science cases of NVST. Then, the basic structures of this telescope and instruments are described in detail. Finally, some typical high resolution data of solar photosphere and chromosphere are also shown.Comment: 16 pages, 14 figures, accepted by RAA (Research in Astronomy and Astrophysics

2,2′-Bis(all­yloxy)-1,1′-binaphth­yl

The complete mol­ecule of the title compound, C26H22O2, is generated by a crystallographic twofold rotation axis. The dihedral angle between the planes of the two symmetry-related naphthalene ring systems is 69.05 (4)°, while that between the naphthalene ring system and the allyl plane is 13.7 (2)°. No hydrogen bonds or aromatic π–π stacking inter­actions are observed

A bibliometric analysis of global research on genome sequencing from 1991 to 2010 Yidan

This study was carried out to evaluate the global scientific production of genome sequencing research to assess the characteristics of the research performances and the research tendencies. Data were obtained from Science Citation Index Expanded database during 1991-2010. Conventional methods including document types, journals, categories, countries and institutions were used to analyze publication output to reveal the global performance. The development of genome sequencing research during last 20 years was described by synthetically analyzing the distribution of words in article title, author keywords, and KeyWords Plus in different periods. The results show that disease and protein related researches were the leading research focuses, and comparative genomics and evolution related research had strong potential in the near future.Key words: Genome sequencing, research trend, scientometrics, science citation index expanded (SCI-Expanded), word cluster analysis, keywords