Improving the Accuracy of Vegetation Index Retrieval for Biomass by Combining Ground-UAV Hyperspectral Data-A New Method for Inner Mongolia Typical Grasslands

Grassland biomass is an important parameter of grassland ecosystems.The complexity of the grassland canopy vegetation spectrum makes the long-term assessment of grassland growth a challenge.Few studies have explored the original spectral information of typical grasslands in Inner Mongolia and examined the influence of spectral information on aboveground biomass(AGB)estimation.In order to improve the accuracy of vegetation index inversion of grassland AGB,this study combined ground and Unmanned Aerial Vehicle(UAV)remote sensing technology and screened sensitive bands through ground hyperspectral data transformation and correlation analysis.The narrow band vegetation indices were calculated,and ground and airborne hyperspectral inversion models were established.Finally,the accuracy of the model was verified.The results showed that:(1)The vegetation indices constructed based on the ASD FieldSpec 4 and the UAV were significantly correlated with the dry and fresh weight of AGB.(2)The comparison between measured R^(2) with the prediction R^(2) indicated that the accuracy of the model was the best when using the Soil-Adjusted Vegetation Index(SAVI)as the independent variable in the analysis of AGB(fresh weight/dry weight)and four narrow-band vegetation indices.The SAVI vegetation index showed better applicability for biomass monitoring in typical grassland areas of Inner Mongolia.(3)The obtained ground and airborne hyperspectral data with the optimal vegetation index suggested that the dry weight of AGB has the best fitting effect with airborne hyperspectral data,where y=17.962e^(4.672x),the fitting R^(2) was 0.542,the prediction R^(2)was 0.424,and RMSE and REE were 57.03 and 0.65,respectively.Therefore,established vegetation indices by screening sensitive bands through hyperspectral feature analysis can significantly improve the inversion accuracy of typical grassland biomass in Inner Mongolia.Compared with ground monitoring,airborne hyperspectral monitoring better reflects the inversion of actual surface biomass.It provides a reliable modeling framework for grassland AGB monitoring and scientific and technological support for grazing management.

Prediction Model of Compressive Strength of Fly Ash-Slag Concrete Based on Multiple Adaptive Regression Splines

Accurate prediction of compressive strength of concrete is one of the key issues in the concrete industry. In this paper, a prediction method of fly ash-slag concrete compressive strength based on multiple adaptive regression splines (MARS) is proposed, and the model analysis process is determined by analyzing the principle of this algorithm. Based on the Concrete Compressive Strength dataset of UCI, the MARS model for compressive strength prediction was constructed with cement content, blast furnace slag powder content, fly ash content, water content, reducing agent content, coarse aggregate content, fine aggregate content and age as independent variables. The prediction results of artificial neural network (BP), random forest (RF), support vector machine (SVM), extreme learning machine (ELM), and multiple nonlinear regression (MnLR) were compared and analyzed, and the prediction accuracy and model stability of MARS and RF models had obvious advantages, and the comprehensive performance of MARS model was slightly better than that of RF model. Finally, the explicit expression of the MARS model for compressive strength is given, which provides an effective method to achieve the prediction of compressive strength of fly ash-slag concrete.

Human induced dryland degradation in Ordos Plateau,China,revealed by multilevel statistical modeling of normalized difference vegetation index and rainfall time-series

Land degradation causes serious environmental problems in many regions of the world, and although it can be effectively assessed and monitored using a time series of rainfall and a normalized difference vegetation index （NDVI） from remotely-sensed imagery, dividing human-induced land degradation from vegetation dynamics due to climate change is not a trivial task. This paper presented a multilevel statistical modeling of the NDVI-rainfall relationship to detect human-induced land degradation at local and landscape scales in the Ordos Plateau of Inner Mongolia, China, and recognized that anthropogenic activities result in either positive （land restoration and re-vegetation） or negative （degradation） trends. Linear regressions were used to assess the accuracy of the multi- level statistical model. The results show that： （1） land restoration was the dominant process in the Ordos Plateau between 1998 and 2012; （2） the effect of the statistical removal of precipitation revealed areas of human-induced land degradation and improvement, the latter reflecting successful restoration projects and changes in land man- agement in many parts of the Ordos; （3） compared to a simple linear regression, multilevel statistical modeling could be used to analyze the relationship between the NDVI and rainfall and improve the accuracy of detecting the effect of human activities. Additional factors should be included when analyzing the NDVI-rainfall relationship and detecting human-induced loss of vegetation cover in drylands to improve the accuracy of the approach and elimi- nate some observed non-significant residual trends.

Study of the asymmetry of hot-spot self-emission imaging of inertial confinement fusion implosion driven by high-power laser facilities

Implosion asymmetry is a crucial problem quenching ignition in the field of inertial confinement fusion.A forward-calculation method based on 1D and 2D hydrodynamic simulations has been developed to generate and study the x-ray images of hot-spot self-emission,indicating asymmetry integrated over the entire drive pulse.It is shown that the x-ray imaging photon energy should be higher to avoid the influence of the remaining shell.The contour level(percentage of the maximum emission intensity)and spatial resolution should be as low as possible,optimally less than 20%and 3μm,for characterization of higher-mode signatures such as Ps-P12 by x-ray self-emission images.On the contrary,signatures of lower-mode such as P2 remain clear at all contour levels and spatial resolutions.These key results can help determine the optimal diagnostics,laser,and target parameters for implosion experiments.Recent typical hot-spot asymmetry measurements and applications on the Shenguang 100 kJ class laser facility are also reported.

Effect of down-regulation of let-7c/g on triggering a double-negative feedback loop and promoting restenosis

Background:Excessive proliferation and migration of vascular smooth muscle cells(VSMCs)are the main causes of restenosis(RS)in diabetic lower extremity arterial disease(LEAD).However,the relevant pathogenic mechanisms are poorly understood.Methods:In this study,we introduced a“two-step injury protocol”rat RS model,which started with the induction of atherosclerosis(AS)and was followed by percutaneous transluminal angioplasty(PTA).Hematoxylin-eosin(HE)staining and immunohistochemistry staining were used to verify the form of RS.Two-step transfection was performed,with the first transfection of Lin28a followed by a second transfection of let-7c and let-7g,to explore the possible mechanism by which Lin28a exerted effects.5-ethynyl-2΄-deoxyuridine(EdU)and Transwell assay were performed to evaluate the ability of proliferation and migration of VSMCs.Western blotting and quantitative real-time polymerase chain reaction(qRT-PCR)were performed to detect the expression of Lin28a protein and let-7 family members.Results:Using a combination of in vitro and in vivo experiments,we discovered that let-7c,let-7g,and microRNA98(miR98)were downstream targets of Lin28a.More importantly,decreased expression of let-7c/let-7g increased Lin28a,leading to further inhibition of let-7c/let-7g.We also found an increased level of let-7d in the RS pathological condition,suggesting that it may function as a protective regulator of the Lin28a/let-7 loop by inhibiting the proliferation and migration of VSMCs.Conclusion:These findings indicated the presence of a double-negative feedback loop consisting of Lin28a and let-7c/let-7g,which may be responsible for the vicious behavior of VSMCs in RS.

Underground logistics systems:Development overview and new prospects in China

1 Introduction Underground logistics systems(ULSs)are a set of self-contained,multimodal,and intelligent physical distribution concepts that enable the automated movement of goods via tunnels and underground pipelines installed within and between cities(Visser,2018).ULSs are also recognized as the fifth type of logistics and generic supply system after seaways,airlines,roads,and railways(Qian and Guo,2007).

Effect of Probe Lifting Height in Jumping Mode AFM for Living Cell Imaging

Atomic force microscopy(AFM)is one of the effective methods for imaging the morphological and physical properties of living cells in a near-physiological environment.However,several problems caused by the adhesion of living cells and extension of the cell membranes seriously affect the image quality during living cell imaging,hindering the study of living cells.In this work,jumping mode AFM imaging was used to image living cells at varied probe lifting heights to meet image quality requirements,and image quality related to the probe lifting height is discussed in detail.The jumping mode was divided into three parts based on the varying heights of the lifted probe,namely near-contact mode,half-jumping mode,and full-jumping mode,and the causes of their imaging drawbacks were analyzed.At an appropriate lifting height,the probe can be completely free from the influence of cell adhesion and self-excited oscillation,thus avoiding the occurrence of“trail”phenomena and invalid points in the imaging of living cells and improving the image quality.Additionally,this work provides a new approach to calculating the lateral force through the adhesion of trace and retrace scanning at a low height,which is important for studying the extension characteristics of the cell membrane.

梗阻性无精子症患者ICSI助孕失败后精道显微重建术可行性与安全性分析——附20例报道

目的旨在探讨梗阻性无精子症(obstructive azoospermia,OA)患者卵胞质内单精子注射(intracytoplasmic sperm injection,ICSI)助孕失败后精道显微重建可行性和安全性。方法回顾性分析2015年9月至2020年5月期间于上海交通大学医学院附属第一人民医院泌尿外科临床医学中心男科收治的20例既往ICSI助孕失败的OA患者资料,总结精道显微重建术特点,并计算其术后复通率与临床妊娠率。结果显微镜下精道重建术中,8例患者存在输精管梗阻,12例患者存在附睾梗阻。输精管梗阻患者中,1例为外伤性OA,行腹腔镜辅助的右侧输精管吻合术(vasovasostomy,VV);7例为幼年斜疝术后OA,其中6例进一步行腹腔镜辅助的VV,1例行输精管附睾交叉吻合术;8例患者中6例术后复通,2例术后女方自然妊娠。附睾梗阻患者均行显微镜下输精管附睾吻合术(vasoepididymostomy,VE),12例患者中6例术后复通,3例术后女方自然妊娠。所有患者术中、术后均未出现明显并发症。结论输精管道显微重建手术是OA患者ICSI助孕失败后的一种有效的补救措施,可帮助患者实现自然妊娠。

Urban underground logistics system in China:Opportunities or challenges?

An urban underground logistics system(ULS)is one important means of solving urban traffic problems that has unique advantages.Freight transportation in China requires a new transportation mode.Therefore,ULS has garnered increasing attention.However,to date,few scholars and practitioners have investigated ULS in China.Although ULS shows good development opportunities,it also faces great challenges.Based on the Macro-environment and situation analysis(PEST-SWOT)model,which is a strategic analysis method that combines both SWOT and PEST to effectively identify advantages,disadvantages,opportunities and threats,this paper first uses PEST to analyze the macro-environment of ULS in China and identify its internal factors(i.e.,advantages and disadvantages)and external factors(i.e.,opportunities and threats).Next,based on the SWOT framework,this paper proposes several development strategies and recommendations that provide a comprehensive and novel perspective to the study of ULS in China.

Environmental filtering does not necessarily prevent trait divergence: a case study of the Xilin River Basin in Inner Mongolia, China

Aims Understanding how environmental factors and human activity drive plant community assembly remains a major challenge in community ecology.Two opposing processes,namely determinis-tic environmental filtering and nondeterministic elements such as interspecies competition,can be quantified by analyzing trait distri-butions in the community-assembly process.Methods We examined the trait-mediated effects of environmental filtering and stochastic process and the distribution over time of nine traits related to vegetative growth,regenerative phase,dispersal capability,decom-position and interspecific competition in plant communities along a degradation gradient in the Xilin River Basin,Inner Mongolia,China.We analyzed the turnover of environmental trait filtering and the diver-gence/convergence of different traits along the degradation gradient.Important Findings Our results showed the following.(i)The patterns of trait distribu-tion and filtering were strongly dependent upon the degradation gradient and trait types.Most traits were filtered intensely in degraded grasslands.(ii)Plants with two different strategies showed contrasting trait-distribution patterns.The traits that were related to biological matter cycling showed divergent pat-terns in highly degraded grasslands,while convergent patterns along the overall gradient were demonstrated in traits associated with other plant strategies.This suggests that the coexistence of multiple‘biological matter cycling-related niches’might be a basic structuring pattern of plant communities in our study area.(iii)The simultaneous occurrence of strong filtering and diver-gence revealed that environmental filtering does not necessar-ily prevent competition,and that different traits show different signatures.

Agent-based modeling approach for evaluating underground logistics system benefits and long-term development in megacities

Mobility,pollution,and other barriers against sustainable goods movement are pushing local administrators to seek innovations in urban transportation infrastructure.The urban underground logistics system(ULS)has been recognized as a prospective alternative to realize large-scale automated freight distribution within and around megacities.This paper proposes an integrated approach combing system dynamics and agent-based modeling to evaluate the long-term development and operating status of a city-wide ULS project.The project boundaries regarding underground network expansion,stakeholders’attributes,and social-environmental benefit metrics were structured as eight highly-interacted agent modules.Critical decision variables of agents in terms of supply-demand equilibrium,investment plan,pricing-to-market and willingness-to-pay were incorporated into three formulized subsystem models.From empirical perspective,the urban territory of Beijing,China,was taken as a case to simulate the development footprints of ULS project under different funding options and market acceptance degrees.Results show that ULS has significant competence with respect to service capacity and profitability,while enabling billions of dollars of external cost-saving annually.Moreover,the comprehensive performance of ULS project regarding economic incomes,benefits,market demand,and construction schedule can reach satisfactory trade-offs through adaptively adjusting the funding policies,incentives and pricing portfolios during project development.