Parkinson's disease (PD) is a neurodegenerative disorder primarily affecting the aging population. The neurophysiological mechanisms underlying parkinsonian symptoms remain unclear. PD affects ...extensive neural networks and a more thorough understanding of network disruption will help bridge the gap between known pathological changes and observed clinical presentations in PD. Development of neuroimaging techniques, especially functional magnetic resonance imaging, allows for detection of the functional connectivity of neural networks in patients with PD. This review aims to provide an overview of current research involving functional network disruption in PD relating to motor and non-motor symptoms. Investigations into functional network connectivity will further our understanding of the mechanisms underlying the effectiveness of clinical interventions, such as levodopa and deep brain stimulation treatment. In addition, identification of PD-specific neural network patterns has the potential to aid in the development of a definitive diagnosis of PD.
Soil erosion control and water resource protection can closely interact during restoration of terrestrial ecosystems. In semi‐arid ecosystems, an urgent issue is how vegetation restoration can ...achieve the goal of soil erosion mitigation and water conservation, which in turn, feeds back to ecosystem functioning.
We reviewed 78 articles from 22 countries in semi‐arid areas to evaluate the effects of vegetation type (i.e. forest, grassland and scrubland) on runoff and sediment yields across different environmental conditions (i.e. vegetation coverage, rainfall intensity, slope gradient and soil texture).
Our meta‐analysis shows that runoff and sediment reduction both increased as the vegetation coverage increased, and tended to be stable when vegetation coverage exceeded 60%. Vegetation provided a greater benefit for sediment reduction than for runoff control under intense rainfall. Grasslands were generally more effective in reducing sediment than other vegetation types. Forests, grasslands and scrublands were most efficient in soil erosion control on 20°–30°, 0°–25° and 10°–25° slopes respectively. Grasslands and scrublands generally performed better with respect to soil erosion control on moderately coarse soils, whereas forests were most effective on medium‐textured and moderately fine soils.
Synthesis and applications. Effective restoration and soil erosion control in semi‐arid ecosystems strongly depends on the selection of vegetation type. Our study further indicates that, for land managers, it is critical to consider local slope, and soil texture, and maintain appropriate vegetation coverage to achieve ecosystem sustainability. Grasslands might be particularly suitable to optimize the trade‐off between soil erosion control and surface water resource in semi‐arid regions.
抽象
半干旱区水保型植被恢复过程中如何实现水土流失控制且维系地表水资源的目标，并进一步反馈于植被生态系统功能，是目前亟待解决的问题。
本研究基于公开发表的来源于22个国家、78篇关于半干旱区植被对土壤侵蚀影响的文献报道，应用Meta‐analysis方法，系统评价了不同植被类型（林地，草地和灌木地）在不同环境条件（植被盖度、降雨强度、坡度和土壤质地）下对径流量和产沙量的影响。
研究结果表明，植被减流效应和减沙效应均随植被盖度的增加而增加，并在植被盖度达到60%时趋于稳定。强降雨下，植被减沙效应大于其减流效应。总体上，三种植被类型中，草地具有最高的减沙效应。林地、草地和灌木地分别在20°‐30°、0°–25°和10º‐25°坡度范围内表现出较高的减流效应和减沙效应。且草地和灌木地在中等粗糙质地土壤中的减流效应和减沙效应较高，林地在中等质地和中等细密质地土壤中的减流效应和减沙效应较高。
综合应用：半干旱区的水保型植被水土流失调控的有效性很大程度上取决于适宜的植被类型。本研究表明，在全球半干旱区，建设草地植被可有效实现水土流失调控与地表水资源维系的权衡。同时，在水保型植被建设过程中，应综合考虑坡度和土壤质地等实际情况并维持适宜的植被盖度，以实现植被生态系统的可持续性。
Effective restoration and soil erosion control in semi‐arid ecosystems strongly depends on the selection of vegetation type. Our study further indicates that, for land managers, it is critical to consider local slope, and soil texture, and maintain appropriate vegetation coverage to achieve ecosystem sustainability. Grasslands might be particularly suitable to optimize the trade‐off between soil erosion control and surface water resource in semi‐arid regions.
In this article we propose a novel D2D Crowd framework for 5G mobile edge computing, where a massive crowd of devices at the network edge leverage network-assisted D2D collaboration for computation ...and communication resource sharing. A key objective of this framework is to achieve energy-efficient collaborative task executions at the network edge for mobile users. Specifically, we first introduce the D2D Crowd system model in detail, and then formulate the energy-efficient D2D Crowd task assignment problem by taking into account the necessary constraints. We next propose a graph-matching-based optimal task assignment policy, and further evaluate its performance through extensive numerical study, which shows superior performance of more than 50 percent energy consumption reduction over the case of local task executions. Finally, we also discuss the directions of extending the D2D Crowd framework by taking into account a variety of application factors.
•Contribution of root decay process on soil water replenishment was assessed.•The macropore formed by decayed root increased the infiltration rate at each stage.•The decayed roots maintain rapid ...preferential infiltration by reducing root density.•Soil water replenishment significantly increased with root decay ages.
Large-scale afforestation has seriously aggravated the consumption of soil water and caused soil desiccation and even the dry soil layers, which has been restricting the survival and sustainability of vegetation in semi-arid areas. How to solve soil water deficit reasonably is an important practical problem we are facing. Here, a field experiment of the decayed roots with different times on soil water infiltration processed was conducted in planted forestland by a double-ring infiltration instrument, to determine the contribution of decayed tree roots on soil water infiltration process and replenishment. Results showed that the decayed process of tree roots in forestland could significantly reduce root density (RD) and increase the relative porosity improved by the roots (RPIR) (P < 0.05). The macropore formed by root decay could not only significantly increase the infiltration rate at each stage (P < 0.05), but also reduce the decrease rate of infiltration rate. Compared with bare land, the decayed roots of the 1–4 yr, the 5–8 yr, and the 9–12 yr increased the amount of soil water replenishment by 37.12%, 217.52%, and 259.85%, respectively. Overall, the decayed tree roots could maintain a relatively high and stable infiltration rate by reduced root density, which increased the effective replenishment of soil water of dry soil layers in forestland. These findings have potential implications for understanding the effect of decay process of tree roots on soil water replenishment, and provide a theoretical basis for the solution to dry soil layers and sustainable management of forestland in semi-arid areas.
•Effects of root and soil water on infiltration rate were studied during different stages.•Root diameter became the main factor affecting soil infiltration along infiltration time.•The ...0–2-mm-diameter root was positively correlated with infiltration rate.•The >4.5-mm-diameter root was negatively correlated with infiltration rate.•Fine roots more determine soil infiltration potential than soil water content.
Soil water is the key limiting factor for achieving sustainable revegetation. Soil infiltration rate plays an important role in determining the inputs from precipitation, which is important for the plant growth and groundwater recharge in semi-arid regions. Soil infiltration rate is generally influenced by belowground biomass (BGB), soil water content (SWC) and other soil properties (total soil porosity, soil mean weight diameter and soil organic carbon). The aim of this study is to understand the effects of plant roots, SWC and other soil properties on soil infiltration rate, and to identify the main factor affecting soil infiltration rate. This study investigated the total soil porosity (TP), soil mean weight diameter (MWD), soil organic carbon (SOC), SWC and plant roots of five grasslands (Bromus inermis, Trifolium repens, Panicum virgatum, Medicago sativa and Miscanthus sinensis). An automatic measurement system of point source device was used to quantify the soil infiltration rate. Results showed that SWC significantly affected the initial infiltration rate (P < 0.05), but plant roots gradually became the main factor affecting soil infiltration rate as the increasing infiltration time. The percentage of root volume (PV) of 0–2 mm was positively correlated with infiltration rate, while the PV of >4.5 mm was negatively correlated with infiltration rate. Our results indicated that fine roots could increase soil organic matters and form soil pores, thus more determining the potential of soil infiltration than soil water content during the short-term vegetation restoration in semi-arid regions.
Green production of NH3, especially the Li‐mediated electrochemical N2 reduction reaction (NRR) in non‐aqueous solutions, is attracting research interest. Controversies regarding the NRR mechanism ...greatly impede its optimization and wide applications. To understand the electrocatalytic process, we treated Au coated carbon fibrous paper (Au/CP) as the model catalyst. In situ XRD confirmed the transformation of lithium intermediates during NRR. Au greatly improved electron transfer kinetics to catalyze metallic Li formation, and accordingly highly accelerated spontaneous NRR. The Faradaic efficiency of NRR on Au/CP reached 34.0 %, and NH3 yield was as high as 50 μg h−1 cm−2. Our research shows that the key step of Li‐mediated non‐aqueous NRR is electrocatalytic Li reduction and offers a novel electrocatalyst design method for Li reduction.
The key step of Li‐mediated non‐aqueous NRR is electrocatalytic Li reduction. Gold greatly improved Li adsorption energy and thus highly accelerated the domino‐like nitrogen reduction reaction (NRR).
Plant diversity can significantly affect the grassland productivity and its stability. However, it remains unclear how plant diversity affects the spatial stability of natural grassland productivity, ...especially in alpine regions that are sensitive to climate change. We analyzed the interaction between plant (species richness and productivity, etc.) and climatic factors (precipitation, temperature, and moisture index, etc.) of alpine natural grassland on the Qinghai-Tibetan Plateau. In addition, we tested the relationship between plant diversity and spatial stability of grassland productivity. Results showed that an increase in plant diversity significantly enhanced community productivity and its standard deviation, while reducing the coefficient of variation in productivity. The influence of plant diversity on productivity and the reciprocal of productivity variability coefficient was not affected by vegetation types. The absolute values of the regression slopes between climate factors and productivity in alpine meadow communities with higher plant diversity were smaller than those in alpine meadow communities with lower plant diversity. In other words, alpine meadow communities with higher plant diversity exhibited a weaker response to climatic factors in terms of productivity, whereas those with lower plant diversity showed a stronger response. Our results indicate that high plant diversity buffers the impact of ambient pressure (e.g., precipitation, temperature) on alpine meadow productivity, and significantly enhanced the spatial stability of grassland productivity. This finding provides a theoretical basis for maintaining the stability of grassland ecosystems and scientifically managing alpine grasslands under the continuous climate change.
Biochar is beneficial for soil amendment, but further research is still required on changes in its physicochemical properties during aging, especially in oxygen-containing functional groups and ...associated adsorption behaviors. Here, we used two different biochars, apple tree branch biochar and maize stalk biochar, and simulated the aging process by using freeze-thaw cycles, dry-wet cycles, and chemical oxidation methods. We investigated the changes in the physicochemical properties and Pb adsorption behavior of the biochars before and after aging treatments. The characterization results showed that the biochar surface structure changed after aging treatments. In general, the specific surface areas (SSAs) of the two biochars increased after chemical oxidation treatment but decreased after the other two treatments. The elemental content analyses indicated a decrease in the C content and increase in O content after artificial aging. In addition, the content of oxygen-containing functional groups in most biochars is increasing after treatment. The increase or decrease in SSA resulted in an increase or decrease in adsorption sites, respectively, thereby enhancing or reducing the adsorption capacity of the biochar. Furthermore, oxygen-containing functional groups enhanced the Pb adsorption capacity of biochar by complexation of free carboxyl and hydroxyl functional groups with Pb. Our research indicated that aging can lead to changes in the Pb adsorption capacity of biochar and that these changes vary depending on the type of aging and biochar. Our results will help to provide a better understanding of the changes in physicochemical properties and Pb adsorption capacity of biochar during the aging process in soil toward making full use of biochar for soil amendment.
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•Different artificial aging techniques have different effects on SSA of biochar.•Different artificial aging techniques lead to changes in the adsorption behavior.•Aging increases oxygen-containing functional groups, enhancing Pb adsorption.•Adsorption process involves complexation, van der Waals force and metal precipitation.
On-going climate warming is threatening the ecological function of grassland ecosystems. However, whether warming has positive effects on community microhabitats and appearance, especially in ...degraded grasslands, remains elusive. To address this issue, we conducted a 2-year field experiment on the severely degraded alpine meadow and undegraded alpine meadow with no warming and warming treatments. Community coverage and height in degraded meadow significantly increased under warming, while these changes were not significant in undegraded meadow. Two-year warming increased the community height of degraded meadow and undegraded meadow by 56.55% and 10.99%, respectively. Warming also increased community coverage by 41.88% in degraded meadow and decreased community coverage by 3.01% in undegraded meadow. Moreover, the response of topsoil temperature to warming was stronger in degraded meadow (6.89%) than in undegraded meadow (− 0.26%), while the negative response of topsoil moisture to warming was weaker in degraded meadow (− 13.95%) than in undegraded meadow (− 20.00%). The SEMs further demonstrated that warming had positive effects on topsoil temperature and community height, while had negative effects on topsoil moisture both in degraded and undegraded meadows. Our results confirm that warming-induced soil drying is an important pathway affecting the community appearance in alpine meadows. These findings highlight that warming has positive effects on community height and coverage and is particularly effective in improving community coverage appearance in severely degraded alpine meadow with topsoil drying.
•Soil erosion control benefit of grasslands and forests are evaluated.•Soil erosion control benefit tends to be stable when vegetation cover exceeds 60%•Sediment reduction is more sensitive than ...runoff control to rainfall intensity.•Forests and grasslands have the best soil erosion control on 20–25° and 15–20° slopes.•Grassland and understory grassland must be promoted in afforestation.
Afforestation reduces soil loss and minimizes landslide risk worldwide, but little is known on the effectiveness of afforestation policies to control soil erosion with different vegetation types in semi-arid areas. Understanding the effectiveness of distinct re-vegetation types under different physiographic conditions (slope gradient, percentage of vegetation cover and rainfall depth) is essential for better policy formulation. This study examines the benefits of soil erosion control in forests and grasslands using published data. This analysis proves that the benefits of vegetation restoration increase with increasing the vegetation cover and tend to be stable when the coverage exceeds 60%. The benefits on sediment yield reduction are more sensitive (vs. runoff reduction benefit) to rainfall intensity. Regarding slopes and soil erosion control, the highest efficiencies appear in forests on 20–25° slopes and in grasslands on 15–20° slopes. Grasslands can effectively reduce soil erosion, as well as forests with understory grasses. For long-term restoration, a 60% vegetation cover maximizes the benefits of reducing soil erosion and maintaining enough soil water supply that prevents possible soil drought. We propose that future afforestation policies should evaluate in advance the appropriate re-vegetation type; meanwhile, suitable vegetation coverage and local physiographic conditions should be considered. Importantly, promotion of grassland and preservation of forest understory grasses must be enforced in land use policies when considering afforestation to minimize soil erosion. We suggest further research to quantify the efficiency of understory vegetation on soil erosion control, which might provide scientific and practical guidance for afforestation policy in semi-arid areas.
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