Search

Abstract The magnetospheric cusp connects the planetary magnetic field to interplanetary space, offering opportunities for charged particles to precipitate to or escape from the planet. Terrestrial cusps are typically found near noon local time, but the characteristics of the Jovian cusp are unknown. Here we show direct evidence of Jovian cusps using datasets from multiple instruments onboard Juno spacecraft. We find that the cusps of Jupiter are in the dusk sector, which is contradicting Earth-based predictions of a near-noon location. Nevertheless, the characteristics of charged particles in the Jovian cusps resemble terrestrial and Saturnian cusps, implying similar cusp microphysics exist across different planets. These results demonstrate that while the basic physical processes may operate similarly to those at Earth, Jupiter’s rapid rotation and its location in the heliosphere can dramatically change the configuration of the cusp. This work provides useful insights into the fundamental consequences of star-planet interactions, highlighting how planetary environments and rotational dynamics influence magnetospheric structures.

The separator with inner channels is designed to solve the inefficiency caused by particle collisions with the wall. Then the response surface methodology is used to optimize this novel separator with the aim of maximizing the separation efficiency and exhaust rate while minimizing the pressure drop simultaneously. Firstly, the Reynolds Stress model and the Euler-Euler model are taken to compare the novel and conventional structures. Secondly, five factors, including inlet velocity (v) of air-particle flow, number of inner channels, axial angle of inner channels, height of inner channels, and number of guide vanes, are selected in the Box-Behnken Design. Thirdly, the quadratic regression equations are established in multi-objective optimization. The research results demonstrate that separation efficiency is improved but the pressure drop is increased in the novel design. Additionally, too large inner channels can lead to a decrease in separation efficiency. The increased height of the inner channels has the most positive impact on the exhaust rate. And the optimization amplitude of the pressure drop is the most remarkable, which is presented as 13.87% at v = 2.5 m/s, 34.49% at v = 4.5 m/s, and 75.49% at v = 6.5 m/s, respectively. Furthermore, the separation efficiency of optimized designs is higher than that of conventional ones at each velocity. The relevant research results can provide an effective guide for improving the efficiency of separators.

The source region of the Yellow River is an important ecological barrier in China. Since the 1990s, under the influence of various factors, its runoff has decreased and the ecological environment has deteriorated, which has attracted great attention of governments. Vegetation is the general term of plant communities covering the surface, which is the natural link between the atmosphere, water and soil. It plays an important role in air regulation, soil conservation and maintaining the stability of the whole ecosystem. Therefore, the study on the differential characteristics and topographic influencing factors of alpine grassland change in the source region of the Yellow River can provide reference for the ecological environment protection in -this region in the future. Based on the remote sensing data of MODIS NDVI, we studied the spatial distribution pattern and temporal variation characteristics of vegetation coverage in the source region of the Yellow River from 2000 to 2009 by means of maximum synthesis method, pixel dichotomy model method and trend analysis method. Furthermore, combined with DEM topographic elevation data, we discussed the influence of topographic factors such as elevation, slope and aspect on fractional vegetation cover (FVC) change. The results showed that: (1) From 2000 to 2009, the FVC in the source region of the Yellow River fluctuated upward, showing the spatial distribution characteristics of the southeast region > the central region > the northwest region; (2) During the ten years from 2000 to 2009, the almost constant of FVC accounted for the largest area, and the areas with increasing FVC mainly concentrated in the northeast and northwest of the studied region, the areas with reduced vegetation coverage were scattered in various places in the studied region, mainly in the form of minimal patches or spots; (3) Different terrain factors had different effects on FVC and the effect of altitude on FVC changes was significantly greater than that of slope and aspect. With the increase of altitude, the proportion of significant reduction in FVC increased firstly and then decreased, while the proportion of significant increase in FVC was decreasing and the proportion of almost unchanged in FVC was increasing; With the increase of slope, the proportion in the above three cases (significant reduction, significant increase and almost unchanged in FVC) was increased, decreased gradually and fluctuated respectively. Under different aspect, the proportion in the above three cases varied little, fluctuating only within 1%.

The source region of the Yellow River is an important source of water conservation in the Qinghai-Tibet Plateau. It is also an animal husbandry base that has a major impact on China. Its ecological environment changes will have a major impact on the safe and sustainable development of water use in Asia. The alpine grassland is an important part of the ecosystem of the Yellow River source area, and the spatial differentiation characteristics of the plaque have important indication significance for the ecological environment succession. In this paper, the alpine grassland in the source region of the Yellow River is taken as the research object. Based on the aerial image of the unmanned aerial vehicle, the EGI threshold method is used to extract the vegetation patches and the bare plaques to obtain high-precision field monitoring data, and the landscape ecology principle is used to analyze the four types of alpine grassland. The morphological characteristics of plaques in different grassland types are studied, and the spatial indications of spatial sequences are used to study the ecological significance of plaque succession. The results show that the number of plaques in swamp meadows, alpine meadows, degraded meadows and alpine grassland increase significantly, the degree of fragmentation increase, and the area of vegetation patches decrease significantly. The area of bare plaque increase significantly as the main trend; the distribution and dominance of landscape plaques are analyzed; the swamp meadow have the highest spread, the best aggregation, and the largest proportion of vegetation plaque, the highest degree of dominance, alpine grassland Conversely; in terms of the complexity of landscape patch shape; the area-weighted shape index and the area-weighted fractal dimension increase with the order of swamp meadows, alpine meadows, degraded meadows and alpine grasslands, tending to be complex plaque space. The ecological risk intensity index of alpine grassland in the source region of the Yellow River varies greatly, and the ecological risk of alpine grassland is high. The results of this study provide data support for elucidating the mechanism of spatial differentiation of alpine grass plaques, provide scientific assistance for grassland monitoring and management in the source area, and it provides an important basis for further discussion on ecological system protection, animal husbandry economy and sustainable development of alpine grassland in China. At the same time, it provides important theoretical support and ecological indication significance for the understanding of the alpine grassland ecosystem succession in the source area of the Yellow River.

China has experienced rapid urbanization and rapid development of economy in the past decades, resulting in severe damage to the urban ecological environment, causing changes in the urban thermal environment and triggering the urban heat island effect. Moreover, the heat island effect has become a hot topic for scholars. The urban heat island effect refers to the phenomenon that the urban surface temperature is significantly higher than that of surrounding suburbs due to the interaction of man-made and natural. The city is considered to be the largest man-made ecosystem. Its heat island effect will not only change the growth habit of urban vegetation， but also affect the outer environment of urban buildings, it further influences human life and has a great negative impact on human health. Therefore, the study of the spatial-temporal variation characteristics of urban heat island effect and its influencing factors can provide data support for the environmental quality control and urban planning of local government departments. Based on the surface temperature remote sensing product data, we studied the spatial distribution characteristics of urban heat island effect in Wuhan from 2001 to 2013, by calculating the temperature difference between the highest and lowest temperatures and the average interval method for heat island classification. We conducted a trend analysis of vegetation cover from 2001 to 2013 initially explore the effects of vegetation cover n heat island effect. The results showed that: (1) From 2001 to 2013, the intensity of heat island in Wuhan was strong in the city center, weaker surrounding city center and the weakest in the suburbs; From 2001 to 2011, the intensity of heat island in Wuhan city was significantly weaken, among which Huangpi, Xinzhou, Jiangxia, Hannan and Caidian district were weaken, and the urban heat island effect of the city center was enhanced; From 2011 to 2013, the intensity of heat island in Wuhan city presented an increasing trend, among which Huangpi district, Xinzhou district and Caidian district were the most obvious, and the urban heat island effect was slightly weaken. (2) Between 2001 and 2013, the vegetation cover in Huangpi district and Xinzhou district increased significantly, and the vegetation cover in the downtown, Jiangxia district and Dongxihu district decreased significantly, corresponding to the urban heat island effect of Wuhan increased volatility. Our results showed that the spatial distribution of urban heat island effect in Wuhan city fluctuated with time during the study period, and the vegetation cover had a significant influence on it.

Drought is an extremely complex natural disaster phenomenon. Sustained drought will lead to the aggravation of water shortage, food production reduction, land desertification and ecological crisis, which will have a great impact on social and economic development, industrial and agricultural production and ecological environment. In recent years, human activities have intensified, the global climate has been warming, and the frequency and intensity of extreme events such as drought have been continuously strengthened, which has been widely concerned by scholars at home and abroad. The Beijing-Tianjin-Hebei region, as the political and cultural center of China, is seriously affected by the drought, which has a certain impact on the social economy of the region. Therefore, it is of great practical significance to carry out remote sensing drought monitoring and understand the temporal and spatial characteristics of drought. Based on MOD13A2 and MOD11A2 in MODIS products, this paper constructed the NDVI-Ts feature space to obtain the Temperature Vegetation Dryness Index (TVDI) in Beijing-Tianjin-Hebei region, and analyzed the spatial and temporal variation characteristics of drought in Beijing-Tianjin-Hebei region from 2001 to 2014 with TVDI as the drought index. The results showed that: (1) the NDVI-Ts feature space in the Beijing-Tianjin-Hebei region showed that when the value of NDVI rose from 0 to 1, the maximum temperature of the surface gradually decreased, while the minimum temperature gradually rose. Both of them had a linear relationship with NDVI, and their spatial shape was similar to a triangle, indicating that the study of drought in Beijing-Tianjin-Hebei was effective by using this spatial feature; (2) the Beijing-Tianjin-Hebei region experienced drought every year in the period of 2001–2014, and the drought was more serious in 2001, 2004, 2008, 2009, 2011 and 2012; (3) The drought in the Beijing-Tianjin-Hebei region was widespread, and the severely arid regions were mainly concentrated in the southern and central regions. In terms of drought intensity, the most frequent occurrences in the period of 2001–2014 were Xingtai, Hengshui, Shijiazhuang, and Handan, and the annual drought in 14 years; the least number of occurrences was Chengde, a total of 4 times; the number of occurrences was second only to Chengde, Tangshan, Zhangjiakou, Qinhuangdao, a total of 7 times. Our results indicated that the Beijing-Tianjin-Hebei region was prone to drought and the drought degree was severe.

China's economy has experienced rapid development in the past few decades, and economic development has also brought serious pollution problems, which has attracted wide attention of scholars at home and abroad. Based on the data of global PM2.5 remote sensing products and China's economic development from 1998 to 2016, the temporal and spatial variations of PM2.5 concentration in China from 1998 to 2016 were analyzed, and the response of PM2.5 concentration in China to economic development was studied. The results showed that the average annual PM2.5 concentration in 1998–2016 showed the spatial distribution characteristics of high in the East and low in the west; during 1998–2016, PM2.5 increased significantly in most regions, but decreased significantly in Inner Mongolia, Shaanxi, Ningxia and Gansu, while PM2.5 did not change significantly in some parts of the central region; during 1998–2007, PM2.5 concentration in most regions of China experienced rapid economic development. The concentration of PM2.5 in a few areas such as Inner Mongolia decreased significantly, while that in Yunnan, Sichuan and Inner Mongolia did not change significantly. During the 10 years of economic slowdown in China (2008–2016), the downward trend of PM2.5 concentration in China was expanding. The concentration of PM2.5 in the central and southern regions decreased or did not change significantly, except in the northwest and a few northeast regions. The change of PM2.5 concentration responds obviously to economic development, but the response of different regional economic development to the change of PM2.5 concentration is different.

Wuzhou reach of Xunjiang River is the most valuable waterway in Guangxi. The research on the evolution of Xunjiang River in Wuzhou is of great practical significance in the aspects of river regulation and water conservancy construction. Based on Landsat images of normal water level in 1997, 2001, 2005, 2009, 2014 and 2018, this paper firstly conducts a quantitative analysis of evolution of the watercourse and shoals in Wuzhou section of Xunjiang River through using RS and GIS. Then the relationships between the changes of river course and sandbars of the research area and the annual rainfall and vegetation coverage of the upstream region are analyzed to determine the causes of the changes of watercourse and shoals of Xunjiang River in Wuzhou. The results show that the riverway contracted with a contraction amount of about 9.93 km2 from 1997 to 2005, and the expansion volume of sandbars was about 12.21 km2. From 2005 to 2014, the watercourse approximately expanded 12.33 km2, and the shoals shrank about 12.49 km2. From 2014 to 2018, the river course was a contraction trend, reducing about 1.57 km2 in area; the sandbars showed an expanding trend, with an expanding amount of about 0.82 km2. The changes of river channel and shoals are mainly influenced by the incoming water and silt from the upper reaches and are related to the annual rainfall and vegetation coverage of the upstream area. The correlation coefficient between watercourse area and upstream annual rainfall is 0.26, and that between riverway area and upstream vegetation coverage is 0.78. However, the correlations between the area of shoals and the annual rainfall and vegetation coverage of the upstream region are contrary to that of the river channel. The correlation coefficients between the area of shoals and the annual rainfall and vegetation coverage of the upstream district are −0.28 and −0.83 respectively.

The rodent disaster is one of the main biological disasters in grassland in northern Xinjiang. The eating and digging behaviors will cause the destruction of ground vegetation, which seriously affected the development of animal husbandry and grassland ecological security. UAV low altitude remote sensing, as an emerging technique with high spatial resolution, can effectively recognize the burrows. However, how to select the appropriate spatial resolution to monitor the calamity of the rodent disaster is the first problem we need to pay attention to. The purpose of this study is to explore the optimal spatial scale on identification of the burrows by evaluating the impact of different spatial resolution for the burrows identification accuracy. In this study, we shoot burrows from different flight heights to obtain visible images of different spatial resolution. Then an object-oriented method is used to identify the caves, and we also evaluate the accuracy of the classification. We found that the highest classification accuracy of holes, the average has reached more than 80 %. At the altitude of 24 m and the spatial resolution of 1cm, the accuracy of the classification is the highest We have created a unique and effective way to identify burrows by using UAVs visible images. We draw the following conclusion: the best spatial resolution of burrows recognition is 1 cm using DJI PHANTOM-3 UAV, and the improvement of spatial resolution does not necessarily lead to the improvement of classification accuracy. This study lays the foundation for future research and can be extended to similar studies elsewhere.

Alzheimer’s disease (AD) is associated with well-established macrostructural and cellular markers, including localized brain atrophy and deposition of amyloid. However, there is growing recognition of the link between cerebrovascular dysfunction and AD, supported by continuous experimental evidence in the animal and human literature. As a result, neuroimaging studies of AD are increasingly aiming to incorporate vascular measures, exemplified by measures of cerebrovascular reactivity (CVR). CVR is a measure that is rooted in clinical practice, and as non-invasive CVR-mapping techniques become more widely available, routine CVR mapping may open up new avenues of investigation into the development of AD. This review focuses on the use of MRI to map CVR, paying specific attention to recent developments in MRI methodology and on the emerging stimulus-free approaches to CVR mapping. It also summarizes the biological basis for the vascular contribution to AD, and provides critical perspective on the choice of CVR-mapping techniques amongst frail populations.

This paper presents a negative type second-generation current conveyor (CCII-). It is based on an inverter-based low-voltage error amplifier, and a negative current mirror. The CCII- could be operated in a very low supply voltage such as ±0.5V. The proposed CCII- has wide input voltage range (±0.24V), wide output voltage (±0.24V) and wide output current range (±24mA). The proposed CCII- has no on-chip capacitors, so it can be designed with standard CMOS digital processes. Moreover, the architecture of the proposed circuit without cascoded MOSFET transistors is easily designed and suitable for low-voltage operation. The proposed CCII- has been fabricated in TSMC 0.18μm CMOS processes and it occupies 1189.91 x 1178.43μm2 (include PADs). It can also be validated by low voltage CCII filters.

This paper presents a 6th-order tunable Butterworth low-pass active filter with Digitally Controlled Differential Difference Current Conveyor (DDCC). This active filter is synthesized using the systematic method of voltage-mode linear transformation (VMLT) which enables the filter use fewer active components, grounded capacitors and grounded resistors to avoid the parasitical effects. The bandwidth of the filter can be tuned by digital switches to adjust the output current of the DDCC. The specifications of the filter are based on 3G standard, and the filter is controlled by 8-bits digital signals. The tunable bandwidth of the filter is from 12 KHz to 2.6 MHz. The filter chip layout is realized by TSMC 0.18 um CMOS 1P6M mixed-mode technology. The supply voltage is 1.8V and the power consumption is 3.6 mW.

Observations from the South African TrigNet global navigation satellite system (GNSS) and vertical total electron content (VTEC) data from the Jason-1 satellite were used to analyze the variations in ionospheric electron density profiles over South Africa before and after the severe geomagnetic storms on 15 May 2005. Computerized ionospheric tomography (CIT) was used to inverse the 3-D structure of ionospheric electron density and its response to the magnetic storms. Inversion results showed that electron density significantly increased at 10:00 UT, 15 May compared with that at the same period on 14 May. Positive ionospheric storms were observed in the inversion region during the magnetic storms. Jason-1 data show that the VTEC observed on descending orbits on 15 May significantly increased, whereas that on ascending orbits only minimally changed. This finding is identical to the CIT result.

The pre-earthquake ionospheric anomalies that occurred before the global M = 7.0+ earthquakes in 2010 are investigated using the total electron content (TEC) from the global ionosphere map (GIM). We analyze the possible causes of the ionospheric anomalies based on the space environment and magnetic field status. Results show that some anomalies are related to the earthquakes. By analyzing the time of occurrence, duration, and spatial distribution of these ionospheric anomalies, a number of new conclusions are drawn, as follows: earthquake-related ionospheric anomalies are not bound to appear; both positive and negative anomalies are likely to occur; and the earthquake-related ionospheric anomalies discussed in the current study occurred 0–2 days before the associated earthquakes and in the afternoon to sunset (i.e. between 12:00 and 20:00 local time). Pre-earthquake ionospheric anomalies occur mainly in areas near the epicenter. However, the maximum affected area in the ionosphere does not coincide with the vertical projection of the epicenter of the subsequent earthquake. The directions deviating from the epicenters do not follow a fixed rule. The corresponding ionospheric effects can also be observed in the magnetically conjugated region. However, the probability of the anomalies appearance and extent of the anomalies in the magnetically conjugated region are smaller than the anomalies near the epicenter. Deep-focus earthquakes may also exhibit very significant pre-earthquake ionospheric anomalies.

Both morphological characteristics and amplified fragment length polymorphism (AFLP) markers were used to validate the genetic fidelity of 1 080 field-grown Echinacea purpurea plants regenerated from leaf explants of donor T5-9. Morphological diagnosis revealed that 1 067 out of 1 080 regenerants were normal, while 13 regenerants were aberrant. AFLP analysis was further performed to assess DNA variations among donor, 43 sampled normal regenerants and all 13 aberrant regenerants. Seven primer combinations generated 471 fragments among donor and normal regenerants, of which 9 fragments were polymorphic. The same primer pairs generated 484 fragments for aberrant regenerants, of which 417 fragments were polymorphic. UPGMA clustering indicated that 42 normal regenerants and donor fell into same cluster at similarity scale of > 0.99, while all 13 aberrant regenerants and one morphologically normal regenerant comprised the other clusters. AFLP analysis indicated that these 14 regenerants are off-types.

Islet autotransplant patients represent excellent subjects to assess the posttransplant impact of islet precursors, as chronic pancreatitis (CP) causes an elevation of ductal cells, pancreatic precursors cells, and hormone-positive acinar cells. The relationship between these cell types and autograft outcomes should be more apparent than would be the case in the context of an allograft program with confounding immunological variables. To improve diabetic control following total pancreatectomy for CP, nonpurified islets were autotransplanted into the liver. Pancreas specimens were recovered from 23 patients and stained for antigens including: insulin, glucagon, cytokeratin 19, cytokeratin 7, and PDX-1. In line with previous reports, the prevalence of ductal cells, non-islet endocrine cells and non-islet PDX-1-expressing cells was significantly higher in CP glands compared with normal pancreata. When correlating follow-up data (i.e., fasting and stimulated C-peptide/glucose levels and HbA1c%) with pancreas immunoreactivity, high levels of ductal cells, non-islet PDX-1-positive cells, and non-islet glucagon-positive cells were associated with superior outcomes, detectable up to 2 years posttransplant. To conclude, the acinar parenchyma and ductal epithelium of the CP pancreas show an upregulation of both endocrine and pre-endocrine cell types, which appear to have a positive effect on islet graft outcomes in autotransplantation setting.

Background: Previous research has verified the role of acute cardiovascular exercise on improving motor learning. This study compares the effects of skill random practice and acute cardiovascular exercise on golf putting performance in college students. Method: 24 healthy adults (10 males, 14 females, aged 21.02+0.70 years) with no golf past experience participated in the study. They were randomized into two groups: skill random practice and acute cardiovascular exercise. A set of baseline, acquisition, and 24-hour retention tests were administered, including a 10-ft. golf putt task. A 3 (time periods) x 2 (groups)/I NO 144 was computed for further data analysis. Results: The performance in golf putts made was not improved immediately after the intervention; however, golf putts made were seen to improve 24 hours after practice compared to the baseline. However, no group difference was noted between skill random practice and acute cardiovascular exercise during acquisition and 24hour retention tests. Conclusion: Our findings suggested the temporal effects on motor learning of a golf putting task. Considering this is the first research effort that pairs skill random practice and acute cardiovascular exercise, there is need for further research to examine the role of exercise intensity and exercise modalities between acute exercise and early motor learning. [ABSTRACT FROM AUTHOR]