Recent Intensified Influence of the Winter North Pacific Sea Surface Temperature on the Mei-Yu Withdrawal Date

Under embargo until: 2022-04-07The mei-yu withdrawal date (MWD) is a crucial indicator of flood/drought conditions over East Asia. It is characterized by a strong interannual variability, but its underlying mechanism remains unknown. We investigated the possible effects of the winter sea surface temperature (SST) in the North Pacific Ocean on the MWD on interannual to interdecadal time scales. Both our observations and model results suggest that the winter SST anomalies associated with the MWD are mainly contributed to by a combination of the first two leading modes of the winter SST in the North Pacific, which have a horseshoe shape (the NPSST). The statistical results indicate that the intimate linkage between the NPSST and the MWD has intensified since the early 1990s. During the time period 1990–2016, the NPSST-related SST anomalies persisted from winter to the following seasons and affected the SST over the tropical Pacific in July. Subsequently, the SST anomalies throughout the North Pacific strengthened the southward migration of the East Asian jet stream (EAJS) and the southward and westward displacement of the western North Pacific subtropical high (WPSH), leading to an increase in mei-yu rainfall from 1 to 20 July. More convincingly, the anomalous EAJS and WPSH induced by the SST anomalies can be reproduced well by numerical simulations. By contrast, the influence of the NPSST on the EASJ and WPSH were not clear between 1961 and 1985. This study further illustrates that the enhanced interannual variability of the NPSST may be attributed to the more persistent SST anomalies during the time period 1990–2016.publishedVersio

Intensified Impacts of Central Pacific ENSO on the Reversal of December and January Surface Air Temperature Anomaly over China since 1997

The reversal of surface air temperature anomalies (SATA) in winter brings a great challenge for short-term climate prediction, and the mechanisms are not well understood. This study found that the reversal of SATA between December and January over China could be demonstrated by the second leading mode of multivariate empirical orthogonal function analysis on the December–January SATA. It further reveals that the central Pacific El Niño–Southern Oscillation (CP ENSO) has contributed more influence on such a reversal of SATA since 1997. CP ENSO shows positive but weak correlations with SATA over China in both December and January during the pre-1996 period, whereas it shows significant negative and positive correlations with the SATA in December and January, respectively, during the post-1997 period. The CP ENSO–related circulations suggest that the change of the Siberian high has played an essential role in the reversal of SATA since 1997. The pattern of sea surface temperature anomalies associated with the CP ENSO leads to a westward-replaced Walker circulation that alters the local meridional circulation and, further, has impacted the Siberian high and SATA over China since 1997. Moreover, the seasonal northward march of the convergence zone from December to January causes a northward-replaced west branch of the Walker circulation in January compared with that in December. The west branch of the Walker circulation in December and January directly modulates local Hadley and Ferrel circulations and then causes contrasting Siberian high anomalies by inducing opposite vertical motion anomalies over Siberia. The reversal of SATA between December and January, therefore, has been more frequently observed over China since 1997. The abovementioned mechanisms are validated by the analysis at pentad time scales and confirmed by numerical simulations.publishedVersio

Immune responses of Helicoverpa armigera to different kinds of pathogens

<p>Abstract</p> <p>Background</p> <p>Insects react against pathogens through innate immunity. The cotton bollworm <it>Helicoverpa armigera </it>(<it>H. armigera</it>) is an important defoliator and an extremely destructive pest insect of many crops. The elucidation of the mechanism of the immune response of <it>H. armigera </it>to various pathogens can provide a theoretical basis for new approaches to biologically control this pest.</p> <p>Results</p> <p>Four kinds of pathogens <it>Bacillus thuringiensis</it>, <it>Klebsiella pneumoniae</it>, <it>Candida albicans</it>, and <it>Autographa californica </it>multiple nucleocapsid nucleopolyhedrovirus harbored green fluorescence protein and polyhedron (<it>Ac</it>MNPV-GFP) were used to challenge the insect. The cellular and humoral immune responses to the pathogens were analyzed in the challenged <it>H. armigera</it>. The results show that in the five kinds of haemocytes, only granulocytes phagocytized the Gram-negative and Gram-positive bacteria and fungi. All haemocytes can be infected by <it>Ac</it>MNPV. Fourteen immune-related genes including pattern recognition receptors (PRRs) such as peptidoglycan recognition proteins (<it>HaPGRP </it>and <it>HaPGRP C</it>) and Gram-Negative Bacteria-Binding Protein (<it>HaGNBP</it>), and antimicrobial peptides (AMPs) such as <it>cecropin-1, 2 </it>and <it>3 </it>(<it>HaCec-1, 2 </it>and <it>3</it>), <it>lysozyme </it>(<it>HaLys</it>), attacin (<it>HaAtt</it>), <it>gallerimycin-like </it>(<it>HaGall</it>), <it>gloverin-like </it>(<it>HaGlo</it>), <it>moricin-like </it>(<it>HaMor</it>), cobatoxin-like (<it>HaCob</it>), <it>galiomicin-like </it>(<it>HaGali</it>), and <it>immune inducible protein </it>(<it>HaIip</it>) appeared in different expression profiles to different pathogen infections. The transcripts of 13 immune related genes (except <it>HaPGRPC</it>) are obviously up-regulated by Gram-positive bacteria. <it>HaCec-1 and 3, HaMor, HaAtt, HaLys</it>, <it>HaIip</it>, <it>HaPGRP </it>and <it>HaGNBP </it>are greatly up-regulated after fungal infection. <it>HaGNBP, HaCec-2, HaGall, HaGlo, HaMor, HaCob, HaGali </it>obviously increased in Gram-negative bacterial infection. Only five genes, <it>HaGNBP, HaCec-1</it>, <it>HaGali</it>, <it>HaGlo</it>, and <it>HaLys</it>, are weakly up-regulated after viral infection. The AMP transcripts had higher expression levels than the PRR transcripts after the microbial challenge.</p> <p>Conclusions</p> <p>These data suggest that the granulocytes are the major phagocytes in <it>H. armigera</it>. All haemocytes can be infected by <it>Ac</it>MNPV. The transcripts of 14 immune related genes have different expression patterns in <it>H. armigera </it>infected by different pathogens, which means that the immune-related genes may have different functions against various kinds of pathogens.</p

Towards Robust SDRTV-to-HDRTV via Dual Inverse Degradation Network

Recently, the transformation of standard dynamic range TV (SDRTV) to high dynamic range TV (HDRTV) is in high demand due to the scarcity of HDRTV content. However, the conversion of SDRTV to HDRTV often amplifies the existing coding artifacts in SDRTV which deteriorate the visual quality of the output. In this study, we propose a dual inverse degradation SDRTV-to-HDRTV network DIDNet to address the issue of coding artifact restoration in converted HDRTV, which has not been previously studied. Specifically, we propose a temporal-spatial feature alignment module and dual modulation convolution to remove coding artifacts and enhance color restoration ability. Furthermore, a wavelet attention module is proposed to improve SDRTV features in the frequency domain. An auxiliary loss is introduced to decouple the learning process for effectively restoring from dual degradation. The proposed method outperforms the current state-of-the-art method in terms of quantitative results, visual quality, and inference times, thus enhancing the performance of the SDRTV-to-HDRTV method in real-world scenarios.Comment: 10 page

Negative thermal expansion in YbMn2Ge2 induced by the dual effect of magnetism and valence transition

AbstractNegative thermal expansion (NTE) is an intriguing property, which is generally triggered by a single NTE mechanism. In this work, an enhanced NTE (αv = −32.9 × 10−6 K−1, ΔT = 175 K) is achieved in YbMn2Ge2 intermetallic compound to be caused by a dual effect of magnetism and valence transition. In YbMn2Ge2, the Mn sublattice that forms the antiferromagnetic structure induces the magnetovolume effect, which contributes to the NTE below the Néel temperature (525 K). Concomitantly, the valence state of Yb increases from 2.40 to 2.82 in the temperature range of 300–700 K, which simultaneously causes the contraction of the unit cell volume due to smaller volume of Yb3+ than that of Yb2+. As a result, such combined effect gives rise to an enhanced NTE. The present study not only sheds light on the peculiar NTE mechanism of YbMn2Ge2, but also indicates the dual effect as a possible promising method to produce enhanced NTE materials