613 research outputs found

    Functional characterization of a short peptidoglycan recognition protein from Chinese giant salamander (Andrias davidianus)

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    This work was supported by the National Natural Science Foundation of China (Grant no. 31302221, 31172408 and 31272666) and Jiangsu Province (Grant no. BK20171274 and BK2011418), and partially by the Opening Project of Jiangsu Key Laboratory of Biochemistry and Biotechnology of Marine Wetland (Grant no. K2016-08). QZ was supported by the “Qinglan” project of Jiangsu province of China.Peer reviewedPublisher PD

    Nearby SNR: a possible common origin to multi-messenger anomalies in spectra, ratios and anisotropy of cosmic rays

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    The multi-messenger anomalies, including spectral hardening or excess for nuclei, leptons, ratios of pˉ/p\bar p/p and B/C, and anisotropic reversal, were observed in past years. AMS-02 experiment also revealed different spectral break for positron and electron at 284 GeV and beyond TeV respectively. It is natural to ask whether all those anomalies originate from one unified physical scenario. In this work, the spatially-dependent propagation (SDP) with a nearby SNR source is adopted to reproduce above mentioned anomalies. There possibly exists dense molecular cloud(DMC) around SNRs and the secondary particles can be produced by pp-collision or fragmentation between the accelerated primary cosmic rays and DMC. As a result, the spectral hardening for primary, secondary particles and ratios of B/CB/C and pˉ/p\bar p/p can be well reproduced. Due to the energy loss at source age of 330 kyrs, the characteristic spectral break-off for primary electron is at about 1 TeV hinted from the measurements. The secondary positron and electron from charged pion take up 5%5\% energy from their mother particles, so the positron spectrum has a cut-off at \sim250 GeV. Therefore, the different spectral break for positron and electron together with other anomalies can be fulfilled in this unified physical scenario. More interesting is that we also obtain the featured structures as spectral break-off at 5 TV for secondary particles of Li, Be, B, which can be served to verify our model. We hope that those tagged structures can be observed by the new generation of space-borne experiment HERD in future.Comment: 16 pages, 12 figure

    Monopole-charged pulsars and relevant issues

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    The aligned pulsars whose rotation axes and magnetic dipole axes are parallel should be positively charged. The total charge of pulsars is calculated after considering the electromagnetic field in and out the star under a specific condition. The statistical relation between the pulsar's rotation energy loss rate (or the period derivative) and the period may hint that the millisecond radio pulsars with small periods could be low-mass bare strange stars.Comment: 4 pages, 1 figures, and 1 tabl

    5 GHz TMRT observations of 71 pulsars

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    We present integrated pulse profiles at 5~GHz for 71 pulsars, including eight millisecond pulsars (MSPs), obtained using the Shanghai Tian Ma Radio Telescope (TMRT). Mean flux densities and pulse widths are measured. For 19 normal pulsars and one MSP, these are the first detections at 5~GHz and for a further 19, including five MPSs, the profiles have a better signal-to-noise ratio than previous observations. Mean flux density spectra between 400~MHz and 9~GHz are presented for 27 pulsars and correlations of power-law spectral index are found with characteristic age, radio pseudo-luminosity and spin-down luminosity. Mode changing was detected in five pulsars. The separation between the main pulse and interpulse is shown to be frequency independent for six pulsars but a frequency dependence of the relative intensity of the main pulse and interpulse is found. The frequency dependence of component separations is investigated for 20 pulsars and three groups are found: in seven cases the separation between the outmost leading and trailing components decreases with frequency, roughly in agreement with radius-to-frequency mapping; in eleven cases the separation is nearly constant; in the remain two cases the separation between the outmost components increases with frequency. We obtain the correlations of pulse widths with pulsar period and estimate the core widths of 23 multi-component profiles and conal widths of 17 multi-component profiles at 5.0~GHz using Gaussian fitting and discuss the width-period relationship at 5~GHz compared with the results at at 1.0~GHz and 8.6~GHz.Comment: 46 pages, 14 figures, 8 Tables, accepted by Ap

    An analysis of risk factors of non-fatal drowning among children in rural areas of Guangdong Province, China: a case-control study

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    <p/> <p>Background</p> <p>Drowning is a major cause of morbidity and mortality for children, yet non-fatal drowning remains poorly understood. The aim of this study was to explore potential modifiable risk factors of non-fatal drowning among children in rural areas of China.</p> <p>Methods</p> <p>A cross-sectional survey was first conducted to obtain non-fatal drowning cases, and 7432 students in grades three to eight from 17 schools participated in the cross sectional survey. Of these, 805 students reported that they experienced non-fatal drowning in the previous year. Then 368 cases were selected randomly to participate in a 1:1 matched case-control study. Each drowning case was matched by one control with the same sex and similar age (the gap less than 2 years) who was selected randomly from the same class.</p> <p>Results</p> <p>Boys were more likely to be involved in non-fatal drowning. Non-fatal drowning most often happened in the afternoon (65.1%) and natural bodies of water were the most common sites of drowning (71.1%). Swimming, diving and playing in natural waters were the leading activities that preceded non-fatal drowning. The significant risk factors for non-fatal drowning were swimming in natural waters without adult supervision (OR = 3.40, 95% CI: 1.92-6.03), playing in or beside natural waters (OR = 2.08, 95% CI: 1.17-3.70) and poor swimming skills (OR = 2.74, 95% CI: 1.14-6.62). However, the following variables were protective factors: supervisor aged 30 years or over (OR = 0.20, 95% CI: 0.09-0.49) and no water activities (OR = 0.36, 95% CI: 0.18-0.70).</p> <p>Conclusions</p> <p>The reduction in dangerous water activities, swimming training and enhancement in supervision among children might decrease the risk of non-fatal drowning.</p