Search

In fringe projection profilometry (FPP), measuring accuracy is closely related to the fringe contrast ratio (CR). Especially for low-reflective scenes, fringe contrast being compressed seriously may inevitably lead to an accuracy decrease. Therefore, a novel high-contrast half-period fringe encoding strategy is developed for the first time. Three half-period fringes generated by folding and fully amplifying three pure sinusoidal fringes with equal phase shifts perform stronger noise resistance than conventional sinusoidal fringes. Due to the folding operation, each half-period fringe naturally has three subregions that map different phase shift amounts, so we especially designed the matching phase extraction algorithm. The algorithm can accurately segment the fringe subregions and then extract the phase from each subregion in a point-to-point manner. Three extracted phase segments with head-to-tail features can be connected seamlessly to produce the final wrapped phase. Experiments compare our method with various advanced encoded fringes and traditional sine fringes across different experimental variables. The results demonstrate that the proposed method exhibits high noise resistance and low-modulation adaptability, resulting in high accuracy, which can be attributed to its superior fringe contrast. Besides, not limited to three-step fringes, the method can be extended to multistep fringes, demonstrating strong flexibility to meet different 3-D measuring requirements. more...

Density peaks clustering algorithm (DP) has difficulty in clustering large-scale data, because it requires the distance matrix to compute the density and aTeX"">$\delta $ -distance for each object, which has $O(n^{2})$ time complexity. Granular ball (GB) is a coarse-grained representation of data. It is based on the fact that an object and its local neighbors have similar distribution and they have high possibility of belonging to the same class. It has been introduced into supervised learning by Xia et al. to improve the efficiency of supervised learning, such as support vector machine, $k$ -nearest neighbor classification, rough set, etc. Inspired by the idea of GB, we introduce it into unsupervised learning for the first time and propose a GB-based DP algorithm, called GB-DP. First, it generates GBs from the original data with an unsupervised partitioning method. Then, it defines the density of GBs, instead of the density of objects, according to the centers, radius, and distances between its members and centers, without setting any parameters. After that, it computes the distance between the centers of GBs as the distance between GBs and defines the $\delta $ -distance of GBs. Finally, it uses GBs’ density and $\delta $ -distance to plot the decision graph, employs DP algorithm to cluster them, and expands the clustering result to the original data. Since there is no need to calculate the distance between any two objects and the number of GBs is far less than the scale of a data, it greatly reduces the running time of DP algorithm. By comparing with $k$ -means, ball $k$ -means, DP, DPC-KNN-PCA, FastDPeak, and DLORE-DP, GB-DP can get similar or even better clustering results in much less running time without setting any parameters. The source code is available at https://github.com/DongdongCheng/GB-DP. more...

Due to simplicity, K-means has become a widely used clustering method. However, its clustering result is seriously affected by the initial centers and the allocation strategy makes it hard to identify manifold clusters. Many improved K-means are proposed to accelerate it and improve the quality of initialize cluster centers, but few researchers pay attention to the shortcoming of K-means in discovering arbitrary-shaped clusters. Using graph distance (GD) to measure the dissimilarity between objects is a good way to solve this problem, but computing the GD is time-consuming. Inspired by the idea that granular ball uses a ball to represent the local data, we select representatives from a local neighborhood, called natural density peaks (NDPs). On the basis of NDPs, we propose a novel K-means algorithm for identifying arbitrary-shaped clusters, called NDP-Kmeans. It defines neighbor-based distance between NDPs and takes advantage of the neighbor-based distance to compute the GD between NDPs. Afterward, an improved K-means with high-quality initial centers and GD is used to cluster NDPs. Finally, each remaining object is assigned according to its representative. The experimental results show that our algorithms can not only recognize spherical clusters but also manifold clusters. Therefore, NDP-Kmeans has more advantages in detecting arbitrary-shaped clusters than other excellent algorithms. more...

Drought stands as a prevalent weather-related natural climatic disaster on a global scale. This study employs twenty GCMs from CMIP6 to investigate hydrological drought characteristics (frequency, duration, and intensity) across Africa under four SSPs (shared socioeconomic pathway) scenarios: SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5 spanning three designated periods: 2021–2040 (near-term), 2041–2060 (mid-term), and 2081–2100 (long-term). The (SPEI) at a 12-month scale and employs bias correction on the multi-model ensemble mean extracted from GCMs of the CMIP6 project via cumulative distribution function (CDF). Mann–Kendall approach was implemented for trend and the SPEI-12-based drought trend from 1979 to 2014 displays a negative trajectory of − 0.05/a for Africa, with similar figures for specific regions: Northern Africa (NAF) at − 0.06/a, Sahara (SAH) at − 0.05/a, Western Africa (WAF) at − 0.01/a, Central Africa (CAF) at − 0.02/a, Eastern Africa (EAF) at − 0.06/a, and Southern Africa (SAF) at − 0.03/a. Notably, the severe drought characteristics are manifested as a 6-month duration, 12 occurrences, and an intensity of − 1.9 events over Africa. The highest duration and frequency are observed over NAF at 7.5-month and 15.1 occurrences, respectively, while the most extreme intensity of − 2.3 events is noted over SAH. In addition, future droughts are expected to be lower frequency, extended duration, and more intense. Extreme scenarios indicate values of − 2.1, − 2.2, and − 2.6 events for Africa in the periods 2021–2040, 2041–2060, and 2081–2100, respectively, compared to − 1.99 in the historical period. The intensity of the drought is expected to increase across all sub-regions, with SAH and NAF projecting the worst conditions with − 2.4, − 2.8, and − 3.0 events respectively for SAH and − 2.2, − 2.7, and − 3.0 events for NAF. Africa’s droughts are predicted to last 6, 8, and 13 months, significantly longer than the usual 4-month period. As the historical events of 17 times is anticipated to drop to 6, 5, and 3 times, respectively. The insights derived from this study could provide a foundational basis for devising effective drought adaptation strategies in Africa. Given the anticipated severity of drought events, prioritizing plans to cope with such challenges is of paramount importance. more...

In this review, instead of summarizing all the advances and progress achieved in stratospheric research, the main advances and new developments in stratosphere-troposphere coupling and stratospheric chemistry-climate interactions are summarized, and some outstanding issues and grand challenges are discussed. A consensus has been reached that the stratospheric state is an important source of improving the predictability of the troposphere on sub-seasonal to seasonal (S2S) time scales and beyond. However, applying stratospheric signals in operational S2S forecast models remains a challenge because of model deficiencies and the complexities of the underlying mechanisms of stratosphere-troposphere coupling. Stratospheric chemistry, which controls the magnitude and distribution of many important climate-forcing agents, plays a critical role in global climate change. Convincing evidence has been found that stratospheric ozone depletion and recovery have caused significant tropospheric climate changes, and more recent studies have revealed that stratospheric ozone variations can even exert an impact on SSTs and sea ice. The climatic impacts of stratospheric aerosols and water vapor are also important. Although their quantitative contributions to radiative forcing have been reasonably well quantified, there still exist large uncertainties in their long-term impacts on climate. The advances and new levels of understanding presented in this review suggest that whole-atmosphere interactions need to be considered in future for a better and more thorough understanding of stratosphere-troposphere coupling and its role in climate change. more...

Based on historical land use for eight periods from 1980 to 2020 and the projected land use under seven Shared Socioeconomic Pathways (SSPs: SSP1-1.9, SSP1-2.6, SSP2-4.5, SSP3-7.0, SSP4-3.4, SSP4-6.0, and SSP5-8.5) from 2021 to 2100, we conducted a study on past and future land use changes in the Qinghai-Tibet Plateau (QTP). This work aims to reveal the land use changes during the carbon peak (2021–2040) and carbon neutrality (2051–2070) periods and at the end of the 21st century (2081–2100). The results show that: (1) in the historical period (1980–2020), the land use types in the QTP were grassland (1475×103km2, 58.2%), barren land (685×103km2, 27.0%), forest land (243×103km2, 9.6%), water (114×103km2, 4.5%), cropland (18.6×103km2, 0.7%) and urban land (0.3×103km2, 0.01%). (2) Relative to the baseline period (1995–2014), the area of grassland is projected to decrease by 0.7% (SSP4-6.0)–5.4% (SSP2-4.5) (0.5–3.9% of the total area of the QTP), 2.8% (SSP4-6.0)–12.5% (SSP3-7.0) (2.1–9.4% of the total area of the QTP) and 6.1% (SSP4-6.0)–21.7% (SSP4-3.4) (4.6–16.4% of the total area of the QTP) in the future three periods. In contrast, the forest land area is projected to increase, by approximately 2.5% (SSP4-6.0) to 30.1% (SSP3-7.0) (0.3–4.3% of the total area of the QTP), 9.2% (SSP4-6.0) to 56.5% (SSP2-4.5) (1.3–8.0% of the total area of the QTP), and 21.2% (SSP4-6.0) to 72.8% (SSP2-4.5) (3.0–10.2% of the total area of the QTP) in the future three periods, respectively. (3) Approximately 0.4 (SSP4-6.0) to 6.9% (SSP5-8.5), 0.9 (SSP4-6.0) to 2.7% (SSP4-3.4), and 0.04 (SSP5-8.5) to 3.5% (SSP1-1.9) of land is expected to convert from grassland to forest land in the future three periods, respectively. The shift from grassland to forest land area is likely to enhance the carbon sink potential of the QTP in the future period. more...

Using the ERA5 reanalysis data, we analyzed the impacts of the Arctic stratospheric polar vortex weakening on Ural Blocking (UB). The results indicate that UB activities are suppressed following the weakening of the polar vortex. Specifically, the probability of UB is significantly reduced, with a maximum decrease of 30% observed around day 24 following the polar vortex weakening. The average life cycle of UB shortens by approximately one day. The amplitude of UB, as measured by the negative potential vorticity (PV) anomalies over the Urals, experiences a significant decrease, particularly with the presence of positive PV anomalies on the western side of Urals. Further analysis indicates that the suppression of UB following the weakened polar vortex is closely linked to both the equatorward horizontal transport of high‐PV air over the Arctic across the dynamic tropopause, and the anomalous increase in static stability over the Urals resulting from a descent of the isentropic surface near the tropopause. Finally, we evaluate the relative roles of the polar vortex weakening and the negative phase of the Arctic Oscillation (AO) in suppressing the development of UB. Our analysis reveals that the impacts of the weak polar vortex on the suppression of UB are stronger and more long‐lasting compared to the negative AO, suggesting that the impacts of the weakened polar vortex on UB cannot be simply explained by the AO response. Anomalies in the polar stratosphere, particularly the weakening of the stratospheric polar vortex, have been shown to significantly improve the predictability of the troposphere on Subseasonal to Seasonal (S2S) time scales. Ural blocking (UB), as an important factor driving the polar vortex weakening, has increasing importance in accurately forecasting the variability of the polar vortex. However, little is known about how the polar vortex affects UB, which is crucial as a better understanding of the dynamical links between them will likely benefit the development of the S2S and operational models. Here we investigate the impacts of the Arctic stratospheric polar vortex weakening on UB. Using statistical methods, we indicate a significant decrease in the probability of occurrence of UB days, as well as reductions in the intensity and average life cycle of the UB events following the polar vortex weakening. Through analyzing potential vorticity and Rossby wave breaking, we delve into the underlying mechanisms by which the weakened polar vortex impacts UB activities, and compare these mechanisms with the effects of the Arctic Oscillation (AO) pathway. Our findings underscore the potential value of a weakened stratospheric polar vortex in improving the predictability of UB activities on S2S time scales. The polar vortex weakening suppresses Ural blocking (UB) activities, resulting in a maximum decrease of 30% in the probability of UBThis suppression is attributed to the equatorward transport of high potential vorticity air and the descent of the isentropic surfaceThe impacts of the weakened polar vortex on UB cannot be solely attributed to the response of the Arctic Oscillation The polar vortex weakening suppresses Ural blocking (UB) activities, resulting in a maximum decrease of 30% in the probability of UB This suppression is attributed to the equatorward transport of high potential vorticity air and the descent of the isentropic surface The impacts of the weakened polar vortex on UB cannot be solely attributed to the response of the Arctic Oscillation more...

ABSTRACTChronic skin ulcers are a primary global health problem. Velvet antler polypeptide (VAP) regulates endothelial cell migration and angiogenic sprout. Adipose-derived stem cells (ADSCs) are reported to make pivotal impacts upon wound healing. This study aimed to explore the role of VAP combined with ADSCs in wound healing of chronic skin ulcers. The effect of VAP on phenotypes of ADSCs, and VAP (PLGA microspheres) combining with ADSCs on wound healing of chronic skin ulcers in vivowas evaluated. VAP generally promoted the proliferation, migration and invasion of ADSCs, and ADSC-induced angiogenesis in human umbilical vein endothelial cells (HUVECs) through PI3K/Akt/HIF-1α pathway. VAP-PLGA (PLGA microspheres) enhanced the promoting effect of ADSCs on wound healing, pathological changes, and angiogenesis in chronic skin ulcers in vivo. VAP-PLGA intensified the effect of ADSCs on up-regulating the levels of p-PI3K/PI3K, p-Akt/Akt, HIF-1α, vascular endothelial growth factor (VEGF), stromal cell-derived factor-1 (SDF-1), C-X-C motif chemokine receptor 4 (CXCR4), angiopoietin-4 (Ang-4), VEGF receptor (VEGFR), and transforming growth factor-β1 (TGF-β1), and down-regulating the levels of interleukin-1 β (IL-1β), IL-18 and IL-6 in wound tissues in chronic skin ulcers in vivo. Collectively, VAP promoted the growth, migration, invasion, and angiogenesis of ADSCs through activating PI3K/Akt/HIF-1α pathway, and VAP-PLGA enhanced the function of ADSCs in promoting wound healing in vivo, which was associated with angiogenesis, inflammation inhibition, and dermal collagen synthesis. more...

High-quality seeds improve the germination rate. Therefore, seed selection before sowing peanuts is crucial. Current peanut seed selection methods include color sorters and sieving machines, which are efficient but lack accuracy due to their reliance on a single indicator. Manual selection is inefficient and subject to subjective influences. Although machine vision and deep learning have performed well in crops such as corn and pepper, most existing research is based on PC or MATLAB platforms, which are not portable and are prone to interference, making them unsuitable for field applications. This study developed a lightweight model for recognizing peanut seed epidermal features. The model was based on deep learning and model quantization techniques. The transfer learning method was used to use four pre-trained models, EfficientNet_b0, EfficientNetv2-b0, MobileNet_v2_35_224, and NasNet_Mobile, as feature extraction layers, the input layer was added before the feature extraction layer, and the dropout and dense layers were added after the feature extraction layer to construct a classifier. The peanut seed selection network(PSSNet) models were constructed and named PSSNet-E, PSSNet-E2, PSSNet-M, and PSSNet-N, respectively, and trained on the Huayu 22 peanut seed dataset constructed in this study. The constructed models were compressed using model quantization technology, and four quantized models were obtained, namely PSSNet-Ef, PSSNet-E2f, PSSNet-Mf, and PSSNet-Nf. Finally, PSSNet-Mf, which had the best model evaluation, was selected as the peanut selection model for this study and deployed on a prototype for testing. Compared with the unquantized model, the size of the quantized model was reduced by two-thirds and the running speed was increased by 37%. A total of 400 Huayu 22 peanut seeds were selected as test samples, and 5 selection tests were conducted.The results showed that the average accuracy was 95.3%, which met the requirements of peanut selection at the production site. more...

It is critical to evaluate the quality of clusters for most cluster analysis. A number of cluster validity indexes have been proposed, such as the Silhouette and Davies–Bouldin indexes. However, these validity indexes cannot be used to process clusters with arbitrary shapes. Some researchers employ graph-based distance to cluster nonspherical data sets, but the computation of graph-based distances between all pairs of points in a data set is time-consuming. A potential solution is to select some representative points. Inspired by this idea, we propose a novel Local Cores-based Cluster Validity (LCCV) index to improve the performance of Silhouette index. Local cores, with local maximum density, are selected as representative points. Since graph-based distance is used to evaluate the dissimilarity between local cores, the LCCV index is effective for obtaining the optimal cluster number for data sets containing clusters with arbitrary shapes. Moreover, a hierarchical clustering algorithm based on the LCCV index is proposed. The experimental results on synthetic and real data sets indicate that the new index outperforms existing ones. more...

AbstractIntracranial aneurysms with poor topography are still difficult and dangerous to be catheterized during endovascular procedures. Here we report a novel coil guiding catheterization technique which could be safe and helpful. Seven aneurysms of 5 cases were embolized with the novel coil guiding catheterization technique in Zhongshan Hospital, Fudan University, from January 2017 to March 2019. All the aneurysms were with poor topography for endovascular embolization. One of the aneurysms was in the posterior communicating segment of internal carotid artery (ICA), three in the ophthalmic segment of ICA, and one in the posterior cerebral artery. Two of the cases had multiple aneurysms. All the aneurysms were catheterized by coil guiding technique and embolized. All the aneurysms were catheterized successfully and safely. The aneurysms embolization results were as follows: Raymond Class 1 occlusion was achieved in 4 aneurysms, Class 2 occlusion in 1, Class 3 occlusion in 2 immediately after the procedure. Follow-up imaging demonstrated all the aneurysms achieved total occlusion. There was no aneurysm re-rupture or patient death. The results indicated that the technique has good safety and effectiveness, with a high rate of technical success and a low rate of periprocedural complications in the reported cases. Thus, appling coil guiding aneurysm catheterization could be considered as a safe and effective method, especially for aneurysms with poor topography. more...

Using the ERA5 reanalysis data, we identify seven easily calculable indices of the strength of the Arctic stratospheric vortex: zonal winds at 10 hPa and temperature or height anomalies at 10 , 50, and 100 hPa. We then compare the climatological statistics and meteorological properties of strong and weak events based on these indices. We particularly consider the sensitivity of the event statistics to the choice of thresholds, the use of these indices in capturing stratosphere–troposphere coupling, and meteorological conditions relevant to chemical ozone depletion. The frequency, seasonal distribution, and interdecadal variability of strong events is more sensitive to threshold or index choice compared to weak events. Composites of polar‐cap geopotential height anomalies are found to differ significantly based on the choice of index. In particular, height‐based events reveal a strong and immediate barotropic response near the central date due to surface pressure fluctuations, making it more difficult to regard central dates of height‐based events as purely stratospheric in origin. We further characterize the relationship of all indices to conditions relevant to chemical ozone depletion, finding that temperature‐based indices in the lower stratosphere perform best. Finally, we present four dynamical benchmarks used to assess and compare the representation of strong events in climate models. Our results highlight the challenges in determining the optimal definition for strong events and emphasize the implications of different choices, providing valuable insights for guiding future studies in defining strong events. At times, the stratospheric polar vortex can undergo significant strengthening. Such strengthening is referred to as the polar vortex intensification event. These events are known to improve subseasonal‐to‐seasonal forecast skills of surface extremes, such as strong winds, and heavy rain. They also have an impact on the Arctic springtime stratospheric ozone concentrations. However, compared to the extensive literature exploring stratospheric sudden warmings, there have been relatively few attempts to establish comprehensive climatology and dynamical benchmarks for strong polar vortex events, and less consensus on how to define strong vortex events. We consider here a range of simple indices of the strength of the polar vortex and evaluate different possible definitions of strong vortex events. To assess these possible definitions, we evaluate how sensitive the climatological statistics of these events are to the choice of definition. We also assess their ability to capture stratosphere–troposphere coupling and meteorological conditions relevant to chemical ozone depletion and show that there are substantial implications for making different choices. Our results highlight the difficulty of settling on a single common definition of strong vortex events and provide useful guidance for selecting an appropriate definition for strong events. The statistics of strong and weak vortex events as defined by several easily calculated indices of stratospheric variability are comparedStatistical and dynamical properties of strong events are found to be more sensitive to the choice of definition than are weak eventsThe character of stratosphere‐troposphere coupling near the central date of strong events depends strongly on the choice of definition The statistics of strong and weak vortex events as defined by several easily calculated indices of stratospheric variability are compared Statistical and dynamical properties of strong events are found to be more sensitive to the choice of definition than are weak events The character of stratosphere‐troposphere coupling near the central date of strong events depends strongly on the choice of definition more...

Sealing quality strongly affects heat pipe performance, but few studies focus on the process of heat pipe sealing. Cold welding sealing technology based on a stamping process is applied for heat pipe sealing. The bonding mechanism of the cold welding sealing process (CWSP) is investigated and compared with the experimental results obtained from the bonding interface analysis. An orthogonal experiment is conducted to observe the effects of various parameters, including the sealing gap, sealing length, sealing diameter, and sealing velocity on bonding strength. A method with the utilization of saturated vapor pressure inside a copper tube is proposed to evaluate bonding strength. A corresponding finite element model is developed to investigate the effects of sealing gap and sealing velocity on plastic deformation during the cold welding process. Effects of various parameters on the bonding strength are determined and it is found that the sealing gap is the most critical factor and that the sealing velocity contributes the least effect. The best parameter combination (A1B3C1D3, with a 0.5 mm sealing gap, 6 mm sealing length, 3.8 mm sealing diameter, and 50 mm/s sealing velocity) is derived within the experimental parameters. Plastic deformation results derived from the finite element model are consistent with those from the experiment. The instruction for the CWSP of heat pipes and the design of sealing dies of heat pipes are provided. more...

To assess the effect of Cytochrome P450 2C9 (CYP2C9)gene polymorphism on pediatric warfarin maintenance dosage requirement. A previously developed search strategy was conducted in PubMed, EMBASE, and the Cochrane Library. Eligible studies published prior to January 27, 2016, were identified and compared against strict inclusion/exclusion criteria. Required data were extracted, and researchers were consulted for additional data if needed. Review Manager version 5.2.3 software was used to analyze the relationship between CYP2C9polymorphisms and warfarin maintenance doses in pediatric patients. Eight articles with a combined total of 507 pediatric patients were included in the meta‐analysis. Maintenance warfarin doses in patients with CYP2C9 *1/*2 genotype,CYP2C9 *1/*3 genotype, and CYP2C9variant carriers which contain at least one variant allele (*2or *3) were from 15% to 41% lower than doses in patients with the wild‐type allele (CYP2C9 *1/*1): All differences were significant with P‐values <.05. The Fontan procedure as a medical indication for anticoagulation was also associated with a lower warfarin maintenance dose; however, target INRrange was not. We found that CYP2C9gene polymorphism (referring to the presence of *1/*2,*1/*3,and variant genotypes in the population in addition to the wild type) was significantly associated with decreased warfarin maintenance dose requirements. Additionally, a specific indication for warfarin, the Fontan procedure, was associated with a lower daily warfarin dose. However, the results of our study require confirmation from more research with larger numbers of pediatric patients. more...

Instance reduction is aimed at reducing prohibitive computational costs and the storage space for instance-based learning. The most frequently used methods include the condensation and edition approaches. Condensation method removes the patterns far from the decision boundary and do not contribute to better classification accuracy, while edition method removes noisy patterns to improve the classification accuracy. In this paper, a new hybrid algorithm called instance reduction algorithm based on natural neighbor and nearest enemy is presented. At first, an edition algorithm is proposed to filter noisy patterns and smooth the class boundaries by using natural neighbor. The main advantage of the algorithm is that it does not require any user-defined parameters. Then, using a new condensation method based on nearest enemy to reduce instances far from decision line. Through this algorithm, interior instances are discarded. Experiments show that the hybrid approach effectively reduces the number of instances while achieves higher classification accuracy along with competitive algorithms. more...

We performed a comparative analysis of human and 12 non-human primates to identify sequence variations in known cancer genes. We identified 395 human-specific fixed non-silent substitutions that emerged during evolution of human. Using bioinformatics analyses for functional consequences, we identified a number of substitutions that are predicted to alter protein function; one of these mutations is located at the most evolutionarily conserved domain of human BRCA2. more...

Using ensemble forecasts from the Global Ensemble Forecast System (GEFS) and controlled integrations with the Weather Research and Forecasting (WRF) model, we explore the stratospheric influence on the development of the 2018 European severe cold air outbreak (CAO). The 2018 CAO set in on 22 February, and its evolution was closely related to a growing tropospheric blocking ridge over the North Atlantic in late February that brought cold air mass into Europe. The event was also preceded by a split of the stratospheric polar vortex on 12 February, after which one child vortex persisted over northeastern Canada. GEFS forecasts initialized 1 week prior to this CAO substantially underestimated its severity, exhibiting large spread correlated with the strength and location of the Atlantic ridge, while forecasts initialized closer to the event captured its severity with higher fidelity. Based on a set of nudged simulations, we show that capturing the evolution of the stratospheric child vortex over northeastern Canada, particularly in the lowermost stratosphere, is of great importance for predicting this CAO, since it substantially affects the strength and location of the Atlantic ridge that in turn determines the evolution and severity of this CAO. When the stratosphere is nudged toward the observed evolution, the northward flow between the child vortex and the Atlantic ridge advects more low potential vorticity air into the Atlantic ridge, and therefore amplifies it. Further experiments demonstrate that the impact of the stratosphere on the development of the ridge is particularly strong over the North Atlantic. Global Ensemble Forecast System forecasts initialized one week prior to the 2018 European severe cold air outbreak (CAO) underestimated its severityControlled Weather Research and Forecasting simulations demonstrate that the stratospheric polar vortex evolution is essential to the synoptic development of the CAOThe impact of the stratospheric polar vortex is particularly strong over the North Atlantic Global Ensemble Forecast System forecasts initialized one week prior to the 2018 European severe cold air outbreak (CAO) underestimated its severity Controlled Weather Research and Forecasting simulations demonstrate that the stratospheric polar vortex evolution is essential to the synoptic development of the CAO The impact of the stratospheric polar vortex is particularly strong over the North Atlantic more...

Psoriasis is a chronic immune-mediated disease of the skin. The incidence of psoriasis among people living with HIV (PLHIV) is higher than that in the general population. The mechanism is complex, the manifestations are varied, and the treatment is difficult. Biotherapy has greatly alleviated psoriasis, but clinical trials often exclude PLHIV, and evidence is limited to case reports. Here, we report a man living with psoriatic arthritis who had poor response to traditional treatments. After receiving the anti-interleukin (IL)-17 monoclonal antibody (ixekizumab), the arthritis symptoms were significantly relieved, while CD4+T cell count increased and the viral load of HIV-1 remained undetectable in combination with antiretroviral therapy (ART). In conclusion, anti-IL-17 monoclonal antibody is a promising and safe treatment for psoriatic arthritis in HIV-positive patients. more...

Reduced Arctic sea‐ice has been proposed to induce severe Eurasian cold events. However, the physical mechanisms for this connection, particularly the relative importance of tropospheric and stratospheric processes, remain unclear. Using ERA‐Interim reanalysis data and WACCM‐SC simulations, we show that the Eurasian cooling induced by reduced sea‐ice centers over eastern Asia and northern Europe. Tropospheric and stratospheric processes contribute roughly equally to the cooling over eastern Asia, while the stratospheric and tropospheric contributions are 60% and 40%, respectively, over northern Europe. In the tropospheric pathway, weakened meridional temperature gradient due to reduced sea‐ice strengthens the Ural blocking and enhances the Siberian High. The enhanced Siberian High favors two streams of cold air‐mass, reaching northern Europe and eastern Asia. In the stratospheric pathway, enhanced upward‐propagating planetary wave 1 causes a shift of the stratospheric polar vortex toward Eurasia and consequently, tropospheric cyclonic anomalies are induced that enhance surface cold anomalies. Recent years of below‐average Arctic sea‐ice have been proposed to be linked to severe cold winters over Eurasia. However, the causality and mechansims of this connection are unclear. Two general pathways have been proposed through which reduced sea‐ice could induce cold winter, namely, the tropospheric and stratospheric pathways. Here, we sought to measure the relative importance of stratospheric and tropospheric processes in this connection. Using observations and model simulations, we find that distinct tropospheric and stratospheric mechanisms contribute roughly equally to the Eurasian winter cooling in response to reduced sea‐ice. In the tropospheric pathway, we find that the Siberian High, an important surface high pressure system for Eurasian winter climate, is enhanced by the reduced Arctic sea‐ice. This favors the intrusion of cold polar air‐mass into Eurasia. In the stratospheric pathway, the stratospheric polar vortex, a strong wintertime circumpolar westerly system (∼15–40 km), is shifted toward Eurasia by the reduced sea‐ice, which also favors the cold anomalies over Euraisa. Distinct tropospheric and stratospheric pathways are equally important for late winter Eurasian cooling in response to Arctic sea‐ice lossReduced sea‐ice strengthens the Siberian High and induces two cold air‐mass streams over Eurasia independent of stratospheric processesSea‐ice‐induced extension of stratospheric polar vortex toward eastern Asia and north Europe leads to the cooling over the two regions Distinct tropospheric and stratospheric pathways are equally important for late winter Eurasian cooling in response to Arctic sea‐ice loss Reduced sea‐ice strengthens the Siberian High and induces two cold air‐mass streams over Eurasia independent of stratospheric processes Sea‐ice‐induced extension of stratospheric polar vortex toward eastern Asia and north Europe leads to the cooling over the two regions more...

Dome seeing degrades the image quality of ground-based telescopes. To achieve dome seeing of the Four Meter Telescope (FMT) less than 0.5 arcsec, structural optimizations based on computational fluid dynamics (CFD) simulation were proposed. The results of the simulation showed that dome seeing of FMT was 0.42 arcsec, which was mainly caused by the slope angle of the dome when the slope angle was 15° and the wind speed was 10 m/s. Furthermore, the lower the air speed was, the less dome seeing would be. Wind tunnel tests (WT) with a 1:120 scaled model of the retractable dome and FMT indicated that the calculated deviations of the CFD simulation used in this paper were less than 20% and the same variations of the refractive index derived from the WT would be a convincing argument for the validity of the simulations. Thus, the optimization of the retractable dome was reliable and the method expressed in this paper provided a reference for the design of next generation of ground-based telescope dome. more...