Finding appropriate incentives to enforce collaborative efforts for governing the commons in risky situations is a long-lasting challenge. Previous works have demonstrated that both punishing ...free-riders and rewarding cooperators could be potential tools to reach this goal. Despite weak theoretical foundations, policy makers frequently impose a punishment-reward combination. Here, we consider the emergence of positive and negative incentives and analyze their simultaneous impact on sustaining risky commons. Importantly, we consider institutions with fixed and flexible incentives. We find that a local sanctioning scheme with pure reward is the optimal incentive strategy. It can drive the entire population toward a highly cooperative state in a broad range of parameters, independently of the type of institutions. We show that our finding is also valid for flexible incentives in the global sanctioning scheme, although the local arrangement works more effectively.
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•Pure reward in a local scheme is more effective both for fixed and flexible incentives•It can drive the entire population toward a highly cooperative state•Increasing the efficiency of the institution can induce the success of pure reward•A local scheme promotes group success more effectively than a global scheme
Global change; Nature conservation; Social sciences; Decision science
This paper reports the first quantitative summer (mean July) temperature reconstruction based on subfossil chironomids from the southeast margin of the Qinghai-Tibetan Plateau (QTP) covering the end ...of the last deglaciation and the entire Holocene, spanning 11,800 cal yr BP to the present. The record is based on 223 chironomid samples throughout a 927 cm sediment core providing a temporal resolution of ∼50 years per sample. We validate the record by applying several statistical reconstruction diagnostics and comparing with pollen and diatom records from the same sediment core. The record suggests the summer temperature varies by ∼2.5 °C across the entire period. A generally warmer period occurred between c.8500 and c.6000 cal yr BP and a cooling trend was initiated from c.5500 cal yr BP. The overall pattern broadly matches the summer insolation at 30°N and the Asian Summer Monsoon records from the surrounding regions suggesting that summer temperatures from the southeast margin of the QTP respond to insolation forcing and monsoon driven variability on a multi-millennial time scale. Modifications of this overall trend are observed on the finer temporal resolution and we suggest that solar activity could be an important mechanism driving the centennial-scale variability. It may have a strengthened effect in the late Holocene when the monsoon influence weakened. Further detailed investigation is needed to disentangle these effects on the climate change over the highlands of southwestern China.
•First high resolution chironomid-based summer temperature reconstruction from China.•Quantitative reconstruction covers the entire Holocene.•Responds to insolation forcing and Asian summer monsoon on a multi-millennial scale.
CoS and NiS nanomaterials anchored on reduced graphene oxide (rGO) sheets, synthesized via combination of hydrothermal with sulfidation process, are studied as high-capacity anode materials for the ...reversible lithium storage. The obtained CoS nanofibers and NiS nanoparticles are uniformly dispersed on rGO sheets without aggregation, forming the sheet-on-sheet composite structure. Such nanoarchitecture can not only facilitate ion/electron transport along the interfaces, but also effectively prevent metal-sulfide nanomaterials aggregation during the lithium reactions. Both the rGO-supported CoS nanofibers (NFs) and NiS nanoparticles (NPs) show superior lithium storage performance. In particular, the CoS NFs-rGO electrodes deliver the discharge capacity as high as 939 mA h g–1 after the 100th cycle at 100 mA g–1 with Coulombic efficiency above 98%. This strategy for construction of such composite structure can also synthesize other metal-sulfide-rGO nanomaterials for high-capacity lithium-ion batteries.
In recent decades, high-resolution (HR) remote sensing images have shown considerable potential for providing detailed information for change detection. The traditional change detection methods based ...on HR remote sensing images mostly only detect a single land type or only the change range, and cannot simultaneously detect the change of all object types and pixel-level range changes in the area. To overcome this difficulty, we propose a new coarse-to-fine deep learning-based land-use change detection method. We independently created a new scene classification dataset called NS-55, and innovatively considered the adaptation relationship between the convolutional neural network (CNN) and the scene complexity by selecting the CNN that best fit the scene complexity. The CNN trained by NS-55 was used to detect the category of the scene, define the final category of the scene according to the majority voting method, and obtain the changed scene by comparison to obtain the so-called coarse change result. Then, we created a multi-scale threshold (MST) method, which is a new method for obtaining high-quality training samples. We used the high-quality samples selected by MST to train the deep belief network to obtain the pixel-level range change detection results. By mapping coarse scene changes to range changes, we could obtain fine multi-type land-use change detection results. Experiments were conducted on the Multi-temporal Scene Wuhan dataset and aerial images of a particular area of Dapeng New District, Shenzhen, where promising results were achieved by the proposed method. This demonstrates that the proposed method is practical, easy-to-implement, and the NS-55 dataset is physically justified. The proposed method has the potential to be applied in the large scale land use fine change detection problem and qualitative and quantitative research on land use/cover change based on HR remote sensing data.
Developing strategies for atomic-scale controlled synthesis of new two-dimensional (2D) functional materials will directly impact their applications. Here, using in situ aberration-corrected scanning ...transmission electron microscopy, we obtain direct insight into the homoepitaxial Frank-van der Merwe atomic layer growth mechanism of TiC single adlayers synthesized on surfaces of Ti
C
MXene substrates with the substrate being the source material. Activated by thermal exposure and electron-beam irradiation, hexagonal TiC single adlayers form on defunctionalized surfaces of Ti
C
MXene at temperatures above 500 °C, generating new 2D materials Ti
C
and Ti
C
. The growth mechanism for a single TiC adlayer and the energies that govern atom migration and diffusion are elucidated by comprehensive density functional theory and force-bias Monte Carlo/molecular dynamics simulations. This work could lead to the development of bottom-up synthesis methods using substrates terminated with similar hexagonal-metal surfaces, for controllable synthesis of larger-scale and higher quality single-layer transition metal carbides.
•The HFRHSC target penetration resistance under multi-impact was assessed.•The poor consolidation conditions may deduce the penetration resistance.•The steel fiber attribute to the better penetration ...resistance.•The damage accumulated by second impact is less significant.
In this paper, the penetration resistance potential of hybrid-fiber-reinforced high-strength concrete (HFRHSC) is investigated at fiber content of 2%. 12 batches of HFRHSC materials with various hybridizations were manufactured for comparative analyses of hybridization. The uniaxial compression tests were conducted to determine the 7-day and 28-day compressive strength indicating that the steel fiber outperforms the polypropylene fiber and polyvinyl alcohol fiber in improving compressive strength. The sequent multi-impact penetration tests for each mixture HFRHSC target were carried out with projectile impact locations in equilateral triangle shape whereas the penetration response was evaluated in terms of depth of penetration (DOP) and crater area. The experimental results indicate that the penetration resistance improvement potential of steel fiber reinforced concrete goes moderately ahead of that of the polypropylene or polyvinyl alcohol fiber reinforced concrete. Besides, the DOP caused by multi-impact implies the penetration resistance is remarkably decayed by the first impact while the second penetration poses much less deterioration. Moreover, cavity expansion analysis together with impact damage were applied to the DOP analytical model for HFRHSC multi-impact penetration whereby the target resistance term corresponding each impact was achieved via best fitting. The accumulated damage is also found to be dependent on the hybridization.
An empirical simulation method to simulate the possible position of shallow rainfall-induced landslides in China has been developed.This study shows that such a simulation may be operated in ...real-time to highlight those areas that are highly prone to rainfall-induced landslides on the basis of the landslide susceptibility index and the rainfall intensity-duration（I-D） thresholds.First,the study on landslide susceptibility in China is introduced.The entire territory has been classified into five categories,among which high-susceptibility regions（Zone 4-＇High＇ and 5-＇Very high＇） account for 4.15%of the total extension of China.Second,rainfall is considered as an external triggering factor that may induce landslide initiation.Real-time satellite-based TMPA3B42 products may provide real rainfall spatial and temporal patterns,which may be used to derive rainfall duration time and intensity.By using a historical record of 60 significant past landslides,the rainfall I-D equation has been calibrated.The rainfall duration time that may trigger a landslide has resulted between 3 hours and 45 hours.The combination of these two aspects can be exploited to simulate the spatiotemporal distribution of rainfall-induced landslide hazards when rainfall events exceed the rainfall I-D thresholds,where the susceptibility category is ＇high＇ or ＇very high＇.This study shows a useful tool to be part of a systematic landslide simulation methodology,potentially providing useful information for a theoretical basis and practical guide for landslide prediction and mitigation throughout China.
•brGDGTs in Lake Ximenglongtan are primarily derived from catchment soil erosion.•brGDGTs-based Holocene MAAT record is presented from southwestern China.•MAAT was low before 7.6 cal kyr BP and ...reached a maximum from 7.6 to 5.5 cal kyr BP.•Boreal summer insolation has forced the temperature variation on Holocene timescale.•Ice-sheets modified the warming of low latitudes through atmospheric circulation.
Here we investigate the sources of branched glycerol dialkyl glycerol tetraethers (brGDGTs) in Lake Ximenglongtan from southwestern China and present a brGDGTs-based Holocene (∼9.4 cal kyr BP) temperature reconstruction. The similarities in the distributions of brGDGTs between surface sediments and catchment soils indicate that soil is the dominant source of brGDGTs. This contrasts with the recent emphasis on lacustrine GDGTs in other regional studies. Holocene temperature evolution is characterized by an early cool phase (with a mean annual air temperature (MAAT) of 12.5 °C) prior to 7.6 cal kyr BP, followed by a rapid warming towards the local thermal maximum (MAAT = 13.8 °C) from 7.6 to 5.5 cal kyr BP and a subsequent long-term cooling that ended at 1.5 cal kyr BP. Temperature changes after 1.5 cal kyr BP show high variability and low correspondence to global climate events such as the Medieval Warm Period. Overall Holocene temperature variation has been primarily controlled by boreal summer insolation changes. The larger amplitude (1.5–4.0 °C) in annual cooling during the early Holocene in MAAT contrasts with summer temperature records from this region (range of cooling 0.3–1.0 °C) and indicates the likely influence of lower winter temperature on MAAT variation. We suggest that substantial remnants of the Northern Hemisphere ice-sheets during the early Holocene enhanced the winter westerlies and East Asian winter monsoon (EAWM), and decreased the winter temperature in southwestern China, leading to a cold early Holocene climate.
Rapid urbanization has resulted in a serious urban heat island effect in the Hangzhou Metropolitan Area of China during the past decades, negatively impacting the area’s sustainable development. ...Using Landsat images from 2000 to 2015, this paper analysed the spatial-temporal patterns in a surface urban heat island (SUHI) and investigated its relationship with urbanization. The derived land surface temperature (LST) and surface urban heat island intensity (SUHII) were used to quantify the SUHI effect. Spatial analysis was employed to illustrate the spatial distribution and evolution of a SUHI. The geographically weighted regression (GWR) model was implemented to identify statistically significant factors that influenced the change of SUHII. The results show that hot and very hot spot areas increased from 387 km2 in 2000 to 615 km2 in 2015, and the spatial distribution changed from a monocentric to a polycentric pattern. The results also indicate that high-LST clusters moved towards the east, which was consistent with urban expansion throughout the study period. These changes mirrored the intensive development of three satellite towns. The statistical analysis suggests that both population density (e.g., changes in population density, CPOPD) and green space (e.g., changes in green space fraction, CGSF) strongly affected the changes in SUHII at different stages of the urbanization process. Increasing in population density has a lastingly effect on elevating the SUHII, whereas increasing green space has a constantly significant effect in mitigating the SUHII. These findings suggest that urban planners and policymakers should protect the cultivated lands in suburbs and exurbs, and make efforts to improve the utilization efficiency of construction land by encouraging the migrating population to live within the existing built-up regions.
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