Bar-induced central star formation as revealed by integral field spectroscopy from CALIFA

We investigate the recent star formation history (SFH) in the inner region of 57 nearly face-on spiral galaxies selected from the Calar Alto Legacy Integral Field Area (CALIFA) survey. For each galaxy we use the integral field spectroscopy from CALIFA to obtain two-dimensional maps and radial profiles of three parameters that are sensitive indicators of the recent SFH: the 4000\AA\ break (D$_n$(4000)), and the equivalent width of H$\delta$ absorption (EW(H$\delta_A$)) and H$\alpha$ emission (EW(H$\alpha$)). We have also performed photometric decomposition of bulge/bar/disk components based on SDSS optical image. We identify a class of 17 "turnover" galaxies whose central region present significant drop in D$_n$(4000), and most of them correspondingly show a central upturn in EW(H$\delta_A$) and EW(H$\alpha$). This indicates that the central region of the turnover galaxies has experienced star formation in the past 1-2 Gyr, which makes the bulge younger and more star-forming than surrounding regions. We find almost all (15/17) the turnover galaxies are barred, while only half of the barred galaxies in our sample (15/32) are classified as a turnover galaxy. This finding provides strong evidence in support of the theoretical expectation that the bar may drive gas from the disc inward to trigger star formation in galaxy center, an important channel for the growth/rejuvenation of pseudobulges in disc galaxies.Comment: 19 pages, 10 figures, ApJ accepte

Thoracic Endovascular Aortic Repair for Type B Aortic Dissection

The incidence of aortic dissection (AD) is estimated to be 1 in 100,000 per year. The onset and progression of AD are rapid. Failure to receive appropriate treatment might lead to death in a short time. Even following active treatment, patients might develop low cardiac output syndrome, severe infection, and hemorrhage, which lead to death. Interventional therapy is a surgical method that has been widely used in Stanford type B AD recently. It is characterized by minimal invasiveness, low incidence of postoperative complications, and low cost. This article will review the interventional treatments for AD and will guide the selection of treatment options

Bright White‐Light‐Emitting Device from Ternary Nanocrystal Composites

A hybrid white-light-emitting device (see figure) whose emission originates only from ternary nanocrystal (quantum dot) composites but whose luminance performance matches the requirements of the lighting industry is demonstrated. The bright white-light emission is obtained by controlling the Forster energy transfer and charge-trapping mechanisms between the different components

White-light-emitting diodes using semiconductor nanocrystals

Light-emitting diodes (LEDs) based on colloidal inorganic semiconductor nanocrystals (QDs) represent a completely new technology platform for the development of flat-panel displays and flat-panel lighting systems. Their major advantages are the easy tuning of the saturated color emission across the visible-NIR range and the high chemical and optical stability of the nanocrystal composites. These characteristics open the way to a new class of hybrid devices in which the low cost, flexible technology of organic LEDs is combined with the long operating lifetime of inorganic semiconductor devices. However, so far, few studies have been reported on white-LEDs based on QDs. This review shows recent developments in the general method for the fabrication of stable white-LEDs comprising QDs with a potentially long lifetime

RF_phage virion: Classification of phage virion proteins with a random forest model

Introduction: Phages play essential roles in biological procession, and the virion proteins encoded by the phage genome constitute critical elements of the assembled phage particle.Methods: This study uses machine learning methods to classify phage virion proteins. We proposed a novel approach, RF_phage virion, for the effective classification of the virion and non-virion proteins. The model uses four protein sequence coding methods as features, and the random forest algorithm was employed to solve the classification problem.Results: The performance of the RF_phage virion model was analyzed by comparing the performance of this algorithm with that of classical machine learning methods. The proposed method achieved a specificity (Sp) of 93.37%%, sensitivity (Sn) of 90.30%, accuracy (Acc) of 91.84%, Matthews correlation coefficient (MCC) of .8371, and an F1 score of .9196

MicroRNA-184 downregulates nuclear receptor corepressor 2 in mouse spermatogenesis

<p>Abstract</p> <p>Background</p> <p>There have been increasing attentions on the role of small RNAs, especially microRNAs in post-transcriptional gene regulation during spermatogenesis. MicroRNA-184 (miR-184) has been shown to be mainly expressed in the testis and brain, and that its expression levels are by far the highest in the testis. However, the role of miR-184 in mammalian spermatogenesis remains unclear.</p> <p>Results</p> <p>In this study, we demonstrated that miR-184 levels were increased during mouse postnatal testis development. Specifically, miR-184 expression was restricted to the germ cells from spermatogonia to round spermatids. Overexpression of miR-184 promoted the proliferation of a germ cell line, GC-1spg. Moreover, miR-184 downregulated <it>nuclear receptor corepressor 2 </it>(<it>Ncor2</it>) by targeting its 3' untranslated region through inhibiting NCOR2 protein translation.</p> <p>Conclusions</p> <p>MiR-184 may be involved in the post-transcription regulation of mRNAs such as <it>Ncor2 </it>in mammalian spermatogenesis.</p