Nonlinear impact of the Arctic Oscillation on extratropical surface air temperature

The Arctic Oscillation (AO) is the leading climate mode of sea level pressure (SLP) anomalies during cold season in the Northern Hemisphere. To a large extent, the atmospheric climate anomalies associated with positive and negative phases of the AO are opposite to each other, indicating linear impact. However, there is also significant nonlinear relationship between the AO and other winter climate variability. We investigate nonlinear impacts of the AO on surface air temperature (SAT) using reanalysis data and a multi-millennial long climate simulation. It is found that SAT response to the AO, in terms of both spatial pattern and magnitude, is almost linear when the amplitude of the AO is moderate. However, the response becomes quite nonlinear as the amplitude of the AO becomes stronger. First, the pattern shift in SAT depends on AO phase and magnitude, and second, the SAT magnitude depends on AO phase. In particular, these nonlinearities are distinct over the North America and Eurasian Continent. Based on the analyses of model output, we suggest that the nonlinear zonal advection term is one of the critical components in generating nonlinear SAT response, particularly over the North America. Key Points: - We investigate nonlinear impacts of the AO on surface air temperature - The response becomes nonlinear for the strong AO events - The nonlinear advection is a critical component for the nonlinear SAT respons

Oxygen-deficient triple perovskites as highly active and durable bifunctional electrocatalysts for oxygen electrode reactions

Highly active and durable bifunctional oxygen electrocatalysts have been of pivotal importance for renewable energy conversion and storage devices, such as unitized regenerative fuel cells and metal-air batteries. Perovskite-based oxygen electrocatalysts have emerged as promising nonprecious metal bifunctional electrocatalysts, yet their catalytic activity and stability still remain to be improved. We report a high-performance oxygen electrocatalyst based on a triple perovskite, Nd1.5Ba1.5CoFeMnO9-delta (NBCFM), which shows superior activity and durability for oxygen electrode reactions to single and double perovskites. When hybridized with nitrogen-doped reduced graphene oxide (N-rGO), the resulting NBCFM/N-rGO catalyst shows further boosted bifunctional oxygen electrode activity (0.698 V), which surpasses that of Pt/C (0.801 V) and Ir/C (0.769 V) catalysts and which, among the perovskite-based electrocatalysts, is the best activity reported to date. The superior catalytic performances of NBCFM could be correlated to its oxygen defect rich structure, lower charge transfer resistance, and smaller hybridization strength between O 2p and Co 3d orbitals

Pathogenicity of severe fever with thrombocytopenia syndrome virus in mice regulated in type I interferon signaling

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging zoonotic disease, which causes high fever, thrombocytopenia, and death in humans and animals in East Asian countries. The pathogenicity of SFTS virus (SFTSV) remains unclear. We intraperitoneally infected three groups of mice: wild-type (WT), mice treated with blocking anti-type I interferon (IFN)-α receptor antibody (IFNAR Ab), and IFNAR knockout (IFNAR−/−) mice, with four doses of SFTSV (KH1, 5 × 105 to 5 × 102 FAID50). The WT mice survived all SFTSV infective doses. The IFNAR Ab mice died within 7 days post-infection (dpi) with all doses of SFTSV except that the mice were infected with 5 × 102 FAID50 SFTSV. The IFNAR−/− mice died after infection with all doses of SFTSV within four dpi. No SFTSV infection caused hyperthermia in any mice, whereas all the dead mice showed hypothermia and weight loss. In the WT mice, SFTSV RNA was detected in the eyes, oral swabs, urine, and feces at 5 dpi. Similar patterns were observed in the IFNAR Ab and IFNAR−/− mice after 3 dpi, but not in feces. The IFNAR Ab mice showed viral shedding until 7 dpi. The SFTSV RNA loads were higher in organs of the IFNAR−/− mice compared to the other groups. Histopathologically, coagulation necrosis and mononuclear inflammatory cell infiltration in the liver and white pulp atrophy in the spleen were seen as the main lesions in the IFN signaling lacking mice. Immunohistochemically, SFTSV antigens were mainly detected in the marginal zone of the white pulp of the spleen in all groups of mice, but more viral antigens were observed in the spleen of the IFNAR−/− mice. Collectively, the IFN signaling-deficient mice were highly susceptible to SFTSV and more viral burden could be demonstrated in various excreta and organs of the mice when IFN signaling was inhibited.The research was supported by the Republic of Korea (Government-wide R&D Fund project for infectious disease research (GFID), HG18C0084)

Rebound phenomenon and its risk factors after hemiepiphysiodesis using tension band plate in children with coronal angular deformity

Background This study was performed to evaluate the rebound phenomenon after the correction of coronal angular deformity by hemiepiphysiodesis using tension band plate in children and to identify its risk factors. Methods We reviewed 50 children (mean age, 11.0 +/- 2.5 years) with 94 physes who had undergone hemiepiphysiodesis using tension band plate due to coronal angular deformity of the lower limb. Patients' demographic data including sex, age at initial surgery and plate removal, affected bone (distal femur or proximal tibia), affected side, and body mass index were collected. The mechanical lateral distal femoral angle (mLDFA) and the mechanical medial proximal tibial angle (mMPTA) were measured from the teleradiogram, Physes were divided into rebound and non-rebound group, and rebound group was defined as the physes which had >= 5 degrees of mLDFA or mMPTA returning to its original deformity. Generalized estimating equation based multivariable analysis was used to identify the risk factors for the rebound phenomenon after the deformity correction. Results A total of 41 physes classified into rebound group and 53 physes into non-rebound group. There were significant differences in the age at initial surgery (p = 0.004), the age at implant removal (p = 0.002), the amount of correction (p = 0.001), and the rate of correction (p < 0.001) between two groups. The rate of correction was significantly associated with the rebound phenomenon (p = 0.044). The risk of rebound phenomenon was 1.2-fold higher as the rate of correction increased by 1 degrees per year. The cutoff values of the correction rate between the two groups were 6.9 degrees/year (p < 0.001). Conclusions This study showed that the rebound group had younger age and faster correction rate than those in the non-rebound group. In addition, the correction rate for deformity was a significant risk factor for the rebound phenomenon after hemiepiphysiodesis using the tension band plate. Close monitoring after implant removal is required for children who have a rapid correction rate over 7 degrees/year.N

Part II model support on a new mechanism for North Pacific Oscillation influence on ENSO

AbstractOwing to the significant influence of El Niño-Southern Oscillation (ENSO) on global climate, how ENSO events are initiated is an intriguing issue. The North Pacific Oscillation (NPO), a primary atmospheric variability over the midlatitude, is a well-known trigger for ENSO events, but the physical linkage is not yet fully understood. Based on observational analyses, in Part I, we proposed a new mechanism that the NPO-related wave activity flux (WAF) could directly induce the equatorial wind anomalies in both upper and lower levels. In this study, we substantiate the impacts of the WAF on tropical circulations using climate models participating in the Coupled Model Intercomparison Project phases 5 and 6 (CMIP5/6). We found that the intensity of the southward WAF over the central Pacific is a paramount factor resulting in intermodel diversity in simulating the NPO–ENSO linkage. By classifying the models into two groups of strong and weak meridional WAF (MWAF), we reveal that the strong MWAF models simulate stronger upper- and lower-level equatorial winds and precipitation anomalies that facilitate the ENSO in subsequent winter. We also reveal that the magnitude of the MWAF is closely related to the model’s climatological meridional wind and meridional shear of climatological zonal wind, emphasizing the role of systematic bias on the ENSO simulation. A comparison of the MWAF impact and seasonal footprinting mechanism demonstrates the dominant influence of the MWAF in determining the diversity of NPO–ENSO relationships.11Ysciescopu

Part I observational study on a new mechanism for North Pacific Oscillation influencing the tropics

AbstractThe North Pacific Oscillation (NPO), a representative midlatitude atmospheric variability, plays an important role in the development of the El Niño-Southern Oscillation (ENSO). To explain this extratropical–tropical linkage, previous studies have focused on the atmospheric boundary layer processes coupled with the mixed-layer ocean. Different from the existing hypothesis, in this study, we propose a new mechanism to link the NPO to ENSO via upper-tropospheric teleconnections. Analyses of the wave activity flux show that wave energy associated with the NPO directly propagates from midlatitude to the tropics, modulating the tropical circulation. During the NPO event, this equatorward energy flux becomes pronounced after the NPO peak phase and persists for more than two weeks. As a result, when a positive NPO grows (here, north anticyclonic–south cyclonic circulation), upper-level easterly wind anomalies are situated along the equatorial Pacific. Accordingly, anomalous lower-level westerly winds simultaneously occur in the equatorial Pacific, contributing to the development of El Niño events. To demonstrate the wave energy propagation via the upper-level troposphere, a stationary wave model experiment was performed with an NPO-like barotropic vorticity forcing. The results show equatorward wave propagation consistent with the observation.11Ysciescopu