The Combined Application of WTP and WTA in Contingent Valuation Methods

The In most contingent valuation (CV) studies, WTP (Willingness to pay) and WTA (Willingness to accept) were often used separately, so protesting or no response or even babbling answers are increasing, and the debate persists over the reliability of CV in economic policy analysis. In order to improve the reliability of CV, WTP and WTA is used syn-chronously to estimate the restoration cost of Maqu grassland ecosystem. Data were partly from questionnaire survey, and partly from interviews and authorities. Before conclusions were derived, we assumed these data that came from interviews and authorities were right. The main result is: If we assumed that the degraded grassland of Maqu needs 10 years to be restored, and divided the restoring period into two stages, then the restoration cost was 0.85 × 108 RMB per year in former 4 years, 0.022 × 108 RMB per year in latter 6 years. The total cost of Maqu grassland restoration was 3.62 × 108 RMB. For all the costs of restoration, WTA occupied 94% and WTP only occupied 6%, suggesting that local grassland degradation was mainly caused by overgrazing and that the overloading livestock must be eliminated in order to achieve restoration successfully. Our research also showed that combining WTP and WTA in contingent valuation is very useful in estimating the cost of environmental improvement projects. Of course, whether these results are right or not, further researches are needed in the future, especially for the actual number of livestock in Maqu grassland.

Chinese Journals' Chief Editors Should Enhance Their Response Rate to Authors

Chief editors are the souls of journals,and can guarantee a journal's success by enhancing the efficiency of the manuscript submission and publication process through promptness and speedy response rates to authors.In this study,a total of 867 international journals—indexed by Science Citation Index,Social Sciences Citation Index,and Arts&Humanities Citation Index,and 567 Chinese journals—indexed by Chinese Science Citation Database and Chinese Social Science Citation Information database,were randomly selected to explore whether significant differences in the response rate and speed exist between chief editors.639 chief editors'email addresses were obtained for the international journals,whereas 357 email addresses were gathered for the Chinese journals.However,due to mail servers,only 274 international and 330 Chinese editors were successfully contacted.All messages contained a questionnaire geared to determine the total length of time required for the manuscript submission and publication process.After two months,a 100% response rate was achieved for international chief editors,while Chinese chief editors had a significantly lower rate(P<0.01)of 30.6%.Nevertheless,for both international and Chinese chief editors,66% and 58% provided a response within 12 hours,respectively.Although several reasons exist for the Chinese journals'lagging behind international journals,this study demonstrates that the response rate of chief editors to authors may also be a contributing factor.Thus,chief editors of Chinese journals should enhance their response rate to improve the current situation and further contribute to Chinese journals'success.

祁连山植物共有种沿海拔梯度的叶片化学计量特征

研究不同海拔地区植物共有种叶片化学计量的变化及其影响因素和适应策略,对于理解全球环境变化中的生物地球化学循环具有重要意义。在本研究中,我们测量了中国西北部祁连山5个海拔高度(海拔2400-3200 m,间隔200 m)的土壤有机碳和养分浓度,以及植物共有种的叶片化学计量,以期能更好地了解山区植物共有种如何对海拔变化表现出适应性反应及未来潜在的环境变化如何影响其叶片功能。研究结果表明,随海拔高度的增加,植物共有种叶片C:N:P化学计量的变化不同。在不同的海拔梯度上,年平均气温(MAT)、土壤全磷(STP)、年平均降水量(MAP)、土壤含水量(SWC)和土壤硝态氮(NO3-N)是影响植物共有种叶片元素浓度的主要因素。而叶片化学计量比主要由MAT、MAP和土壤全氮(STN)决定。MAT和MAP对植物共有种叶片元素浓度和叶化学计量比均有显著影响。研究区植物生长主要受到磷的限制。研究结果不仅凸显了植物的可塑性生存策略,还有助于加深我们对植物叶片化学计量学的理解,建立单个植物物种和植物群落与共有种之间的联系。

Terrain relief periods of loess landforms based on terrain profiles of the Loess Plateau in northern Shaanxi Province,China

The Loess Plateau is densely covered by numerous types of gullies which represent different soil erosion intensities.Therefore,research on topographic variation features of the loess gullies is of great significance to environmental protection and ecological management.Using a5 m digital elevation model and data from a national geographic database,this paper studies different topographical areas of the Loess Plateau,including Shenmu,Suide,Yanchuan,Ganquan,Yijun,and Chunhua,to derive representative gully terrain profile data of the sampled areas.First,the profile data are standardized in MATLAB and then decomposed using the ensemble empirical mode decomposition method.Then,a significance test is performed on the results;the test confidence is 95% to 99%.The most reliable decomposition component is then used to calculate the relief period and size of the gullies.The results showed that relief periods of the Chunhua,Shenmu,Yijun,Yuanchuan,Ganquan,and Suide gullies are 1110.14 m,1096.85 m,1002.49 m,523.48 m,498.12 m,and 270.83 m,respectively.In terms of gully size,the loess landforms are sorted as loess fragmented tableland,aeolian and dune,loess tableland,loess ridge,loess hill and loess ridge,and loess hill,in descending order.Taken together,the gully terrain features of the sample areas and the results of the study are approximately consistent with the actual terrain profiles.Thus,we conclude that ensemble empirical mode decomposition is a reliable method for the study of the relief and topography of loess gullies.

Far-field super-resolution imaging by nonlinearly excited evanescent waves

Abbe’s resolution limit,one of the best-known physical limitations,poses a great challenge for any wave system in imaging,wave transport,and dynamics.Originally formulated in linear optics,the Abbe limit can be broken using nonlinear optical interactions.We extend the Abbe theory into a nonlinear regime and experimentally demonstrate a far-field,label-free,and scan-free super-resolution imaging technique based on nonlinear four-wave mixing to retrieve near-field scattered evanescent waves,achieving a sub-wavelength resolution ofλ∕5.6.This method paves the way for numerous new applications in biomedical imaging,semiconductor metrology,and photolithography.

Optically induced transparency in a micro-cavity

Electromagnetically induced transparency has the unique ability to optically control transparency windows with low light in atomic systems.However,its practical applications in quantum physics and information science are limited due to rigid experimental requirements.Here we demonstrate a new mechanism of optically induced transparency in a micro-cavity by introducing a four-wave mixing gain to nonlinearly couple two separated resonances of the micro-cavity in an ambient environment.A signature Fano-like resonance was observed owing to the nonlinear interference of the two coupled resonances.Moreover,we show that the unidirectional gain of the four-wave mixing can lead to the remarkable effect of non-reciprocal transmission at the transparency windows.Optically induced transparency may offer a unique platform for a compact,integrated solution to all-optical and quantum information.

Sensitivity analysis for leaf area index （LAI） estimation from CHRIS/PROBA data

Sensitivity analyses were conducted for the retrieval of vegetation leaf area index （LAI） from multi- angular imageries in this study. Five spectral vegetation indices （VIs） were derived from Compact High Resolution Imaging Spectrometer onboard the Project for On Board Autonomy （CHRIS/PROBA） images, and were related to LAI, acquired from in situ measurement in Jiangxi Province, China, for five vegetation communities. The sensitivity of LAI retrieval to the variation of VIs from different observation angles was evaluated using the ratio of the slope of the best-fit linear VI-LAI model to its root mean squared error. Results show that both the sensitivity and reliability of VI-LAI models are influenced by the heterogeneity of vegetation communities, and that perfor- mance of vegetation indices in LAI estimation varies along observation angles. The VI-LAI models are more reliable for tall trees than for low growing shrub-grasses and also for forests with broad leaf trees than for coniferous forest. The greater the tree height and leaf size, the higher the sensitivity. Forests with broad-leaf trees have higher sensitivities, especially at oblique angles, while relatively simple-structured coniferous forests, shrubs, and grasses show similar sensitivities at all angles. The multi-angular soil and/or atmospheric parameter adjustments will hope- fully improve the performance of VIs in LAI estimation, which will require further investigation.

Regional features of topographic relief over the Loess Plateau,China:evidence from ensemble empirical mode decomposition

Landforms with similar surface matter compositions,endogenic and exogenic forces,and development histories tend to exhibit significant degrees of self-similarity in morphology and spatial variation.In loess hill-gully areas,ridges and hills have similar topographic relief characteristics and present nearly periodic variations of similar repeating structures at certain spatial scales,which is termed the topographic relief period(TRP).This is a relatively new concept,which is different from the degree of relief,and describes the fluctuations of the terrain from both horizontal and vertical(cross-section)perspectives,which can be used for in-depth analysis of 2-D topographic relief features.This technique provides a new perspective for understanding the macro characteristics and differentiation patterns of loess landforms.We investigate TRP variation features of different landforms on the Loess Plateau,China,by extracting catchment boundary profiles(CBPs)from 5 m resolution digital elevation model(DEM)data.These profiles were subjected to temporal-frequency analysis using the ensemble empirical mode decomposition(EEMD)method.The results showed that loess landforms are characterized by significant regional topographic relief;the CBP of 14 sample areas exhibited an overall pattern of decreasing TRPs and increasing topographic relief spatial frequencies from south to north.According to the TRPs and topographic relief characteristics,the topographic relief of the Loess Plateau was divided into four types that have obvious regional differences.The findings of this study enrich the theories and methods for digital terrain data analysis of the Loess Plateau.Future study should undertake a more in-depth investigation regarding the complexity of the region and to address the limitations of the EEMD method.