8,501 research outputs found

    Newly recognized mosquito-associated viruses in mainland China, in the last two decades

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    There are four principal arboviruses in mainland China. Two kinds of them are mosquito-borne viruses, namely Japanese encephalitis virus and dengue virus, which lead to Japanese encephalitis, and dengue fever/dengue hemorrhagic fever respectively; the other two are tick-borne viruses, namely tick-borne encephalitis virus and Crimean-Congo hemorrhagic fever virus (also known as Xinjiang hemorrhagic fever virus), which contribute to tick-borne encephalitis and Xinjiang hemorrhagic fever respectively. With exception of these four main arboviruses, many other mosquito-associated viruses have been isolated and identified in recent years. These newly isolated and identified mosquito-associated viruses are probably responsible for human and animal infections and diseases. The purpose of this review is to describe the newly isolated mosquito-associated viruses in mainland China which belong to five viral families, including their virological properties, phylogenetic relationships, serological evidence, as well as to appeal the public health concentration worldwide

    Note on a non-critical holographic model with a magnetic field

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    We consider a noncritical holographic model constructed from an intersecting brane configuration D4/D4ˉ\bar{\rm{D4}}-D4 with an external magnetic field. We investigate the influences of this magnetic field on strongly coupled dynamics by the gauge/gravity correspondence.Comment: 18 pages, references added and typos revise

    Biodegradation of polycyclic aromatic hydrocarbons (PAHs) by white rot-fungus Pseudotrametes gibbosa isolated from the boreal forest in Northeast China

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    This study compared laccase production and the degradation of polycyclic aromatic hydrocarbons (PAHs) by  aboriginal white rot-fungus Pseudotrametes gibbosa (found in the northeast forest area of China) and Pleurotus ostreatus (which has been studied both domestically in China and overseas). The results showed that the laccase activity of P. gibbosa was 2841.3 U/l, which was 6 times more than that of P. ostreatus under the same culture conditions. The degradation of Anthracene and pyrene induced by P. gibbosa were 43.43 and 24.26%, while the removal efficiencies induced by P. ostreatus were only 30.12 and 18.76%. The results also showed a positive correlation between the PAHs degradation and laccase activity, and Pseudotrametes gibbosa had significant potential due to its higher laccase production and more potent degradation of PAHs. This study provides technical support for pollution amelioration using aboriginal white-rot fungus.Key words: White-rot fungus, laccase, polycyclic aromatic hydrocarbons, degradation

    Holographic phase transition in a non-critical holographic model

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    We consider a holographic model constructed from the intersecting brane configuration D4-D4ˉ\bar{\rm{D4}}/D4 in noncritical string theory. We study the chiral phase diagram of this holographic QCD-like model with a finite baryon chemical potential through the supergravity dual approximation.Comment: 14 pages, reference adde

    Calibration of GRB Luminosity Relations with Cosmography

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    For the use of Gamma-Ray Bursts (GRBs) to probe cosmology in a cosmology-independent way, a new method has been proposed to obtain luminosity distances of GRBs by interpolating directly from the Hubble diagram of SNe Ia, and then calibrating GRB relations at high redshift. In this paper, following the basic assumption in the interpolation method that objects at the same redshift should have the same luminosity distance, we propose another approach to calibrate GRB luminosity relations with cosmographic fitting directly from SN Ia data. In cosmography, there is a well-known fitting formula which can reflect the Hubble relation between luminosity distance and redshift with cosmographic parameters which can be fitted from observation data. Using the Cosmographic fitting results from the Union set of SNe Ia, we calibrate five GRB relations using GRB sample at z1.4z\leq1.4 and deduce distance moduli of GRBs at 1.4<z6.61.4< z \leq 6.6 by generalizing above calibrated relations at high redshift. Finally, we constrain the dark energy parameterization models of the Chevallier-Polarski-Linder (CPL) model, the Jassal-Bagla-Padmanabhan (JBP) model and the Alam model with GRB data at high redshift, as well as with the Cosmic Microwave Background radiation (CMB) and the baryonic acoustic oscillation (BAO) observations, and we find the Λ\LambdaCDM model is consistent with the current data in 1-σ\sigma confidence region.Comment: 15 pages, 4 figures, 2 tables; accepted for publication in IJMP

    A Comprehensive Analysis of Fermi Gamma-Ray Burst Data. IV. Spectral Lag and its Relation to E p Evolution

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    The spectral evolution and spectral lag behavior of 92 bright pulses from 84 gamma-ray bursts observed by the Fermi Gamma-ray Burst Monitor (GBM) telescope are studied. These pulses can be classified into hard-to-soft pulses (H2S; 64/92), H2S-dominated-tracking pulses (21/92), and other tracking pulses (7/92). We focus on the relationship between spectral evolution and spectral lags of H2S and H2S-dominated-tracking pulses. The main trend of spectral evolution (lag behavior) is estimated with ( ), where E p is the peak photon energy in the radiation spectrum, t + t 0 is the observer time relative to the beginning of pulse −t 0, and is the spectral lag of photons with energy E with respect to the energy band 8–25 keV. For H2S and H2S-dominated-tracking pulses, a weak correlation between and k E is found, where W is the pulse width. We also study the spectral lag behavior with peak time of pulses for 30 well-shaped pulses and estimate the main trend of the spectral lag behavior with . It is found that is correlated with k E . We perform simulations under a phenomenological model of spectral evolution, and find that these correlations are reproduced. We then conclude that spectral lags are closely related to spectral evolution within the pulse. The most natural explanation of these observations is that the emission is from the electrons in the same fluid unit at an emission site moving away from the central engine, as expected in the models invoking magnetic dissipation in a moderately high-σ outflow

    A comprehensive analysis of Fermi Gamma-Ray Burst Data: IV. Spectral lag and Its Relation to Ep Evolution

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    The spectral evolution and spectral lag behavior of 92 bright pulses from 84 gamma-ray bursts (GRBs) observed by the Fermi GBM telescope are studied. These pulses can be classified into hard-to-soft pulses (H2S, 64/92), H2S-dominated-tracking pulses (21/92), and other tracking pulses (7/92). We focus on the relationship between spectral evolution and spectral lags of H2S and H2S-dominated-tracking pulses. %in hard-to-soft pulses (H2S, 64/92) and H2S-dominating-tracking (21/92) pulses. The main trend of spectral evolution (lag behavior) is estimated with logEpkElog(t+t0)\log E_p\propto k_E\log(t+t_0) (τ^kτ^logE{\hat{\tau}} \propto k_{\hat{\tau}}\log E), where EpE_p is the peak photon energy in the radiation spectrum, t+t0t+t_0 is the observer time relative to the beginning of pulse t0-t_0, and τ^{\hat{\tau}} is the spectral lag of photons with energy EE with respect to the energy band 88-2525 keV. For H2S and H2S-dominated-tracking pulses, a weak correlation between kτ^/Wk_{{\hat{\tau}}}/W and kEk_E is found, where WW is the pulse width. We also study the spectral lag behavior with peak time tpEt_{\rm p_E} of pulses for 30 well-shaped pulses and estimate the main trend of the spectral lag behavior with logtpEktplogE\log t_{\rm p_E}\propto k_{t_p}\log E. It is found that ktpk_{t_p} is correlated with kEk_E. We perform simulations under a phenomenological model of spectral evolution, and find that these correlations are reproduced. We then conclude that spectral lags are closely related to spectral evolution within the pulse. The most natural explanation of these observations is that the emission is from the electrons in the same fluid unit at an emission site moving away from the central engine, as expected in the models invoking magnetic dissipation in a moderately-high-σ\sigma outflow.Comment: 58 pages, 11 figures, 3 tables. ApJ in pres

    Bright 22 μ\mum Excess Candidates from WISE All-Sky Catalog and Hipparcos Main Catalog

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    In this paper we present a catalog which includes 141 bright candidates (10.27\leq10.27 mag, V band) showing the infrared (IR) excess at 22 μ\mum. Of which, 38 stars are known IR excess stars or disk, 23 stars are double or multiple stars and 4 are Be stars. While the remaining more than 70 stars are identified as the 22 μ\mum excess candidates in our work. The criterion of selecting candidates is Ks[22]μmK_s-[22]_{\mu m}. All these candidates are selected from \emph{WISE} All-sky data cross-correlated with \emph{Hipparcos} Main Catalog and the likelihood-ratio technique is employed. Considering the effect of background, we introduce the \emph{IRAS} 100 μ\mum level to exclude the high background. We also estimated the coincidence probability of these sources. In addition, we presented the optical to mid-infrared SEDs and optical images of all the candidates, and gave the observed optical spectra of 6 stars with NAOC's 2.16-m telescope. To measure for the dust amount around each star, the fractional luminosity is also provided. We also test whether our method of selecting IR excess stars can be used to search for extra-solar planets, we cross-matched our catalog with known IR-excess stars having planets but none is matched. Finally, we give the fraction of stars showing IR-excess for different spectral type of main-sequence stars.Comment: 45 pages, 16 figures, 4 tables. Accepted for publication in ApJ
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