•Drought pattern of SCPSDI was obtained by REOF and wavelet analysis.•Relationships between RPCs and climate indices were analyzed.•Four moisture-related spatial patterns were objectively ...defined.•The PDSI increased in Xinjiang, while decreased in the eastern Hexi Corridor.•The drought evolution of this arid region may affected by VPA, AO, and NAO.
We studied the drought patterns in the arid region of northwestern China between 1960 and 2010 using the Palmer Drought Severity Index (PDSI). The general evolution of drought was obtained by empirical orthogonal function (EOF), rotated empirical orthogonal function (REOF), the Mann–Kendall test, and the continuous wavelet transform method. Additionally, relationships between rotated principal component time series (RPCs) and seven selected climate indices were analyzed. The results showed that: (1) Four moisture-related spatial patterns (North Xinjiang, western South Xinjiang, Central Xinjiang, and the Hexi Corridor) were objectively defined by REOF analysis. These patterns are related to distinct geographical areas and are associated with distinct temporal variations. (2) The PDSI increased significantly in most regions of Xinjiang, while decreased in the eastern Hexi Corridor. The significant 4–8year band is the major period band for the annual and seasonal PDSI derived. (3) The seasonal REOFs (RPCs) and EOFs (PCs) have consistent spatial distribution patterns with the annual REOF. The seasonal trends of PDSI are also the same as the annual PDSI trends, indicating space–time consistency between annual PDSI and seasonal PDSI. (4) The drought evolution in this region is affected by the area of northern hemisphere polar vortex, the Arctic Oscillation, and the North Atlantic Oscillation. In addition, the changes of drought in South Xinjiang and the Hexi Corridor may also be associated with the Tibetan Plateau High. Changes in drought pattern are expected to have a strong impact on the economic livelihood of the region, especially for agricultural production.
The arid region of Northwest China, located in the central Asia, responds sensitively to global climate change. Based on the newest research results, this paper analyzes the impacts of climate change ...on hydrology and the water cycle in the arid region of Northwest China. The analysis results show that: (1) In the northwest arid region, temperature and precipitation experienced “sharply” increasing in the past 50 years. The precipitation trend changed in 1987, and since then has been in a state of high volatility, during the 21st century, the increasing rate of precipitation was diminished. Temperature experienced a “sharply” increase in 1997; however, this sharp increasing trend has turned to an apparent hiatus since the 21st century. The dramatic rise in winter temperatures in the northwest arid region is an important reason for the rise in the average annual temperature, and substantial increases in extreme winter minimum temperature play an important role in the rising average winter temperature; (2) There was a significant turning point in the change of pan evaporation in the northwest arid area in 1993, i.e., in which a significant decline reversed to a significant upward trend. In the 21st century, the negative effects of global warming and increasing levels of evaporation on the ecology of the northwest arid region have been highlighted; (3) Glacier change has a significant impact on hydrology in the northwest arid area, and glacier inflection points have appeared in some rivers. The melting water supply of the Tarim River Basin possesses a large portion of water supplies (about 50%). In the future, the amount of surface water will probably remain at a high state of fluctuation.
•The sharp increasing of temperature has turned to hiatus since the 21st century.•Precipitation sharply increased in 1987, since then has been in a high volatility.•Negative effects of global warming on the ecology have been highlighted.•The amount of surface water will probably remain at a high state of fluctuation.
During robot-assisted rehabilitation, failure to recognize lower limb movement may efficiently limit the development of exoskeleton robots, especially for individuals with knee pathology. A major ...challenge encountered with surface electromyography (sEMG) signals generated by lower limb movements is variability between subjects, such as motion patterns and muscle structure. To this end, this paper proposes an sEMG-based lower limb motion recognition using an improved support vector machine (SVM). Firstly, non-negative matrix factorization (NMF) is leveraged to analyze muscle synergy for multi-channel sEMG signals. Secondly, the multi-nonlinear sEMG features are extracted, which reflect the complexity of muscle status change during various lower limb movements. The Fisher discriminant function method is utilized to perform feature selection and reduce feature dimension. Then, a hybrid genetic algorithm-particle swarm optimization (GA-PSO) method is leveraged to determine the best parameters for SVM. Finally, the experiments are carried out to distinguish 11 healthy and 11 knee pathological subjects by performing three different lower limb movements. Results demonstrate the effectiveness and feasibility of the proposed approach in three different lower limb movements with an average accuracy of 96.03% in healthy subjects and 93.65% in knee pathological subjects, respectively.
Pancreatic ductal adenocarcinoma (PDA) is the most lethal of common human malignancies, with no truly effective therapies for advanced disease. Preclinical studies have suggested a therapeutic ...benefit of targeting the Hedgehog (Hh) signaling pathway, which is activated throughout the course of PDA progression by expression of Hh ligands in the neoplastic epithelium and paracrine response in the stromal fibroblasts. Clinical trials to test this possibility, however, have yielded disappointing results. To further investigate the role of Hh signaling in the formation of PDA and its precursor lesion, pancreatic intraepithelial neoplasia (PanIN), we examined the effects of genetic or pharmacologic inhibition of Hh pathway activity in three distinct genetically engineered mouse models and found that Hh pathway inhibition accelerates rather than delays progression of oncogenic Kras-driven disease. Notably, pharmacologic inhibition of Hh pathway activity affected the balance between epithelial and stromal elements, suppressing stromal desmoplasia but also causing accelerated growth of the PanIN epithelium. In striking contrast, pathway activation using a small molecule agonist caused stromal hyperplasia and reduced epithelial proliferation. These results indicate that stromal response to Hh signaling is protective against PDA and that pharmacologic activation of pathway response can slow tumorigenesis. Our results provide evidence for a restraining role of stroma in PDA progression, suggesting an explanation for the failure of Hh inhibitors in clinical trials and pointing to the possibility of a novel type of therapeutic intervention.
In recent years, climate extreme events have caused increasing direct economic and social losses in the arid region of northwestern China. Based on daily temperature and precipitation data from 1960 ...to 2010, this paper discussed the linear trend and abrupt changes of climate indices. The general evolution was obtained by the empirical orthogonal function (EOF), the Mann-Kendall test, and the distribution-free cumulative sum chart (CUSUM) test. The results are as follows: (1) climate showed a warming trend at annual and seasonal scale, with all temperature indices exhibiting statistically significant changes. The warm indices have increased, with 1.37%days/decade of warm days (TX90p), 0.17°C/decade of warmest days (TXx) and 1.97days/decade of warm spell duration indicator (WSDI), respectively. The cold indices have decreased, with −1.89%days/decade, 0.65°C/decade and −0.66days/decade for cold nights (TN10p), coldest nights (TNn) and cold spell duration indicator (CSDI), respectively. The precipitation indices have also increased significantly, coupled with the changes of magnitude (max 1-day precipitation amount (RX1day)), frequency (rain day (R0.1)), and duration (consecutive dry days (CDD)). (2) Abrupt changes of the annual regional precipitation indices and the minimum temperature indices were observed around 1986, and that of the maximum temperature indices were observed in 1996. (3) The EOF1 indicated the overall coherent distribution for the whole study area, and its principal component (PC1) was also observed, showing a significant linear trend with an abrupt change, which were in accordance with the regional observation results. EOF2 and EOF3 show contrasts between the southern and northern study areas, and between the eastern and western study areas, respectively, whereas no significant tendency was observed for their PCs. Hence, the climate indices have changed significantly, with linear trends and abrupt changes noted for all climate indices, which will have serious impacts on water resources and ecological environment in the arid region of China.
•Extreme was coupled with the changes of magnitude, frequency, and duration.•Abrupt changes were observed in the year of 1986 and 1996•EOF2 of the indices showed positive-negative pattern in North Xinjiang and South Xinjiang.
Climate extremes have more direct and significant impact than average state on social and ecological systems. Using data from 68 meteorological stations in the arid region of northwest China (ARNC) ...for the past 50years (1961–2010), we conducted Mann–Kendal nonparametric trend analysis on the time series of temperature and precipitation extremes in different regions of the ARNC. The analysis found that in the past 50years, 1) overall for the ARNC, three temperature indices, including the annual mean temperature (Tav), annual average daily minimum temperature (Tnav), and annual average daily maximum temperature (Txav) all had increasing trends; 2) overall for the ARNC, three precipitation indices, including the annual mean precipitation (Pav), number of days for daily precipitation≥10mm (Pn10mm) and annual maximum number of consecutive wet days (Pxcwd) also all had increasing trends; 3) regionally, Tnav and Pn10mm in north Xinjiang considerably increased; in both north and south Xinjiang, annual maximum number of consecutive dry days (Pxcdd) considerably decreased, whereas Pxcwd considerably increased; and the main pattern of Hexi Corridor is that Txav considerably increased; 4) it appears that the increase of Tav in the ARNC in the past 50years is related to the increase of Tnav and Txav; and 5) the increase of precipitation in north and south Xinjiang is a result of the joint effect of the increases of Pn10mm and Pxcwd. Generally, in ARNC, during the past 50years the dynamics of climate extremes are closely related to the dynamics of climate average state, and are major contributors to the overall climate change.
•Precipitation indices have strong regional variation.•Temperature indices had significant positive trends in the entire region.•Climate extremes are major factors for the rise of climate average state.
Drought stress significantly impacts global rice production, highlighting the critical need to understand the genetic basis of drought resistance in rice. Here, through a genome-wide association ...study, we reveal that natural variations in DROUGHT RESISTANCE GENE 9 (DRG9), encoding a double-stranded RNA (dsRNA) binding protein, contribute to drought resistance. Under drought stress, DRG9 condenses into stress granules (SGs) through liquid-liquid phase separation via a crucial α-helix. DRG9 recruits the mRNAs of OsNCED4, a key gene for the biosynthesis of abscisic acid, into SGs and protects them from degradation. In drought-resistant DRG9 allele, natural variations in the coding region, causing an amino acid substitution (G267F) within the zinc finger domain, increase DRG9's binding ability to OsNCED4 mRNA and enhance drought resistance. Introgression of the drought-resistant DRG9 allele into the elite rice Huanghuazhan significantly improves its drought resistance. Thus, our study underscores the role of a dsRNA-binding protein in drought resistance and its promising value in breeding drought-resistant rice.
Human activity recognition (HAR) is a hot research topic which aims to understand human behavior and can be applied in various applications. However, transitions between activities are usually ...disregarded due to their low incidence and short duration when compared against other activities, while in fact, transitions can affect the performance of the recognition system if not dealt with properly. In this paper, we propose and implement a systematic human activity recognition method to recognize basic activities (BA) and transitional activities (TA) in a continuous sensor data stream. First, raw sensor data are segmented into fragments with sliding window and the features are constructed based on window segmentation. Then, cluster analysis with K-Means is used to aggregate activity fragments into periods. Next, generally, realize the classification of BA and TA according to the shortest duration of the BA, and then deal with the hidden phenomenon of BA. Third, the fragments between adjacent BA are evaluated to decide whether they are TA or disturbance process. Finally, random forest classifier is used to accurately recognize BA and TA. The proposed method is evaluated on the public dataset SBHAR. The results demonstrate that our method effectively recognizes different activities and can deliver high accuracy with all activities considered.
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