Gamma-ray bursts (GRBs) are believed to belong to two classes and they are conventionally divided according to their durations. This classification scheme is not satisfied due to the fact that duration distributions of the two classes are heavily overlapped. We collect a new sample (153 sources) of GRBs and investigate the distribution of the logarithmic deviation of the E p value from the Amati relation. The distribution possesses an obvious bimodality structure and it can be accounted for by the combination of two Gaussian curves. Based on this analysis, we propose to statistically classify GRBs in the well-known E p vs. E iso plane with the logarithmic deviation of the E p value. This classification scheme divides GRBs into two groups: Amati type bursts and non-Amati type bursts. While Amati type bursts well follow the Amati relation, non-Amati type bursts do not. It shows that most Amati type bursts are long duration bursts and the majority of non-Amati type bursts are short duration bursts. In addition, it reveals that Amati type bursts are generally more energetic than non-Amati type bursts. An advantage of the new classification is that the two kinds of burst are well distinguishable and therefore their members can be identified in certainty.

Pneumonia caused by Acinetobacter baumannii has become a serious threat to the elderly. However, there are no experimental studies on the relevance between aging and A. baumannii infections. Here, we established an aged pneumonia mouse model by non-invasive intratracheal inoculation with A. baumannii. Higher mortality was observed in aged mice along with increased bacterial burdens and more severe lung injury. Increased inflammatory cell infiltration and enhanced pro-inflammatory cytokines at 24 hours post infection were detected in aged mice than those in young mice. Moreover, infected aged mice had lower myeloperoxidase levels in lungs and less reactive oxygen species-positive neutrophils in bronchoalveolar lavage fluid compared with infected young mice. Reduced efficacy of imipenem/cilastatin against A. baumannii was detected in aged mice. Vaccination of formalin-fixed A. baumannii provided 100% protection in young mice, whereas the efficacy of vaccine was completely diminished in aged mice. In conclusion, aging increased susceptibility to A. baumannii infection and impaired efficacies of antibiotics and vaccine. The aged mice model of A. baumannii pneumonia is a suitable model to study the effects of aging on A. baumannii infection and assess the efficacies of antibiotics and vaccines against A. baumannii for the elderly.

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This work aims to measure the properties of continuum and emission lines around C iv, Mg ii, Hβ, and Hα for the quasars observed by the extended Baryon Oscillation Spectroscopic Survey (eBOSS) during the first two years. We determine the quasar redshifts based on narrow [O iii] λ5007, broad Mg ii λ2799, and/or C iv λ1548 emission lines. The comparisons between the visual inspection redshifts included in DR14Q and the redshifts determined by us suggest that the visual inspection redshifts would be robust. We also infer the virial black hole mass of quasars based on C iv, Mg ii, Hβ, and/or Hα broad emission lines, using empirical relationships reported by previous studies. Systematic differences are remarkable among different line-based mass estimators reported by previous studies. Using the empirical relationship (Equation (1)), we improve the line-based mass estimators by recalibrating new coefficient (a, b), so that different line-based mass estimators are more consistent. We find that (a, b) = (0.96, 0.5), (0.91, 0.5), (0.82, 0.5), and (0.77, 0.5) are the best choices for the Hα-, Hβ-, Mg ii-, and C iv-based mass estimators, respectively. All these above properties are publicly available. We also find that the line and continuum luminosities are tightly correlated with each other. The Balmer lines show a negative Baldwin effect, while the metal lines display a positive Baldwin effect. In addition, we find that tight correlations are indwelled in different line luminosities.