SPS监管差异对中国果蔬类农产品出口贸易的影响——基于农药最大残留限量标准视角

利用2022年中国对157个国家(地区)出口50种果蔬类农产品贸易数据,采用Heckman两阶段模型,基于农药最大残留限量(MRLs)视角,实证分析SPS监管差异对中国果蔬类农产品出口贸易的影响。结果表明:SPS监管差异抑制中国果蔬类农产品出口的二元边际,即贸易成本效应大于竞争优势效应,贸易成本效应抑制扩展边际和集约边际,而竞争优势效应仅促进集约边际;SPS监管差异对中国向发达国家出口以及对蔬菜农产品出口的抑制作用更大;杀菌剂监管差异对集约边际和扩展边际均具有抑制作用,而杀虫剂监管差异仅抑制集约边际。据此,提出对标国际高标准SPS措施、帮助中小型企业克服技术难关、宣传食品安全理念等政策建议。

石榴蔗糖代谢相关酶SPS和INV基因家族鉴定与表达分析

蔗糖磷酸合成酶(SPS)和蔗糖转化酶(INV)是蔗糖代谢的关键调控酶,在植物生长发育过程中起重要作用。本研究利用生物信息学和荧光定量PCR等分子手段,鉴定石榴SPS和INV基因家族成员,分析其理化性质、保守结构域、保守基序、二级结构、亚细胞定位、系统进化关系和表达模式。结果表明,从石榴基因组中鉴定出4个SPS基因和11个INV基因,其编码蛋白均为不稳定蛋白,具有典型的保守结构域,家族成员间特征motif数量和种类大致相同,蛋白结构高度保守;这些蛋白不均匀地分布在染色体上,均定位于叶绿体中,二级结构主要由α-螺旋和无规则卷曲组成。石榴SPS和INV基因家族成员间存在不同程度的亲缘关系,与巨桉同源性较高;不同SPS和INV基因在石榴果实不同发育时期的表达模式存在差异,PgINV3在9月15日(果实增大期)表达水平最高,显著高于其他时期。本研究结果对解析石榴果实中蔗糖代谢的分子机理具有重要意义。

Construction of a Computational Scheme for the Fuzzy HIV/AIDS Epidemic Model with a Nonlinear Saturated Incidence Rate

This work aimed to construct an epidemic model with fuzzy parameters.Since the classical epidemic model doesnot elaborate on the successful interaction of susceptible and infective people,the constructed fuzzy epidemicmodel discusses the more detailed versions of the interactions between infective and susceptible people.Thenext-generation matrix approach is employed to find the reproduction number of a deterministic model.Thesensitivity analysis and local stability analysis of the systemare also provided.For solving the fuzzy epidemic model,a numerical scheme is constructed which consists of three time levels.The numerical scheme has an advantage overthe existing forward Euler scheme for determining the conditions of getting the positive solution.The establishedscheme also has an advantage over existing non-standard finite difference methods in terms of order of accuracy.The stability of the scheme for the considered fuzzy model is also provided.From the plotted results,it can beobserved that susceptible people decay by rising interaction parameters.

A Non-Parametric Scheme for Identifying Data Characteristic Based on Curve Similarity Matching

For accurately identifying the distribution charac-teristic of Gaussian-like noises in unmanned aerial vehicle(UAV)state estimation,this paper proposes a non-parametric scheme based on curve similarity matching.In the framework of the pro-posed scheme,a Parzen window(kernel density estimation,KDE)method on sliding window technology is applied for roughly esti-mating the sample probability density,a precise data probability density function(PDF)model is constructed with the least square method on K-fold cross validation,and the testing result based on evaluation method is obtained based on some data characteristic analyses of curve shape,abruptness and symmetry.Some com-parison simulations with classical methods and UAV flight exper-iment shows that the proposed scheme has higher recognition accuracy than classical methods for some kinds of Gaussian-like data,which provides better reference for the design of Kalman filter(KF)in complex water environment.

A Neural-network-based Alternative Scheme to Include Nonhydrostatic Processes in an Atmospheric Dynamical Core

Here,a nonhydrostatic alternative scheme(NAS)is proposed for the grey zone where the nonhydrostatic impact on the atmosphere is evident but not large enough to justify the necessity to include an implicit nonhydrostatic solver in an atmospheric dynamical core.The NAS is designed to replace this solver,which can be incorporated into any hydrostatic models so that existing well-developed hydrostatic models can effectively serve for a longer time.Recent advances in machine learning(ML)provide a potential tool for capturing the main complicated nonlinear-nonhydrostatic relationship.In this study,an ML approach called a neural network(NN)was adopted to select leading input features and develop the NAS.The NNs were trained and evaluated with 12-day simulation results of dry baroclinic-wave tests by the Weather Research and Forecasting(WRF)model.The forward time difference of the nonhydrostatic tendency was used as the target variable,and the five selected features were the nonhydrostatic tendency at the last time step,and four hydrostatic variables at the current step including geopotential height,pressure in two different forms,and potential temperature,respectively.Finally,a practical NAS was developed with these features and trained layer by layer at a 20-km horizontal resolution,which can accurately reproduce the temporal variation and vertical distribution of the nonhydrostatic tendency.Corrected by the NN-based NAS,the improved hydrostatic solver at different horizontal resolutions can run stably for at least one month and effectively reduce most of the nonhydrostatic errors in terms of system bias,anomaly root-mean-square error,and the error of the wave spatial pattern,which proves the feasibility and superiority of this scheme.

Quantum-Resistant Multi-Feature Attribute-Based Proxy Re-Encryption Scheme for Cloud Services

Cloud-based services have powerful storage functions and can provide accurate computation.However,the question of how to guarantee cloud-based services access control and achieve data sharing security has always been a research highlight.Although the attribute-based proxy re-encryption(ABPRE)schemes based on number theory can solve this problem,it is still difficult to resist quantum attacks and have limited expression capabilities.To address these issues,we present a novel linear secret sharing schemes(LSSS)matrix-based ABPRE scheme with the fine-grained policy on the lattice in the research.Additionally,to detect the activities of illegal proxies,homomorphic signature(HS)technology is introduced to realize the verifiability of re-encryption.Moreover,the non-interactivity,unidirectionality,proxy transparency,multi-use,and anti-quantum attack characteristics of our system are all advantageous.Besides,it can efficiently prevent the loss of processing power brought on by repetitive authorisation and can enable precise and safe data sharing in the cloud.Furthermore,under the standard model,the proposed learning with errors(LWE)-based scheme was proven to be IND-sCPA secure.

A Practical Regular LDPC Coded Scheme for Physical-Layer Information Security

In this paper,we aim to design a practical low complexity low-density parity-check(LDPC)coded scheme to build a secure open channel and protect information from eavesdropping.To this end,we first propose a punctured LDPC coded scheme,where the information bits in a codeword are punctured and only the parity check bits are transmitted to the receiver.We further propose a notion of check node type distribution and derive multi-edge type extrinsic information transfer functions to estimate the security performance,instead of the well-known weak metric bit error rate.We optimize the check node type distribution in terms of the signal-to-noise ratio(SNR)gap and modify the progressive edge growth algorithm to design finite-length codes.Numerical results show that our proposed scheme can achieve a lower computational complexity and a smaller security gap,compared to the existing scrambling and puncturing schemes.

Stability Analysis of Inverse Lax-Wendroff Procedure for a High order Compact Finite Difference Schemes

This paper considers the finite difference(FD)approximations of diffusion operators and the boundary treatments for different boundary conditions.The proposed schemes have the compact form and could achieve arbitrary even order of accuracy.The main idea is to make use of the lower order compact schemes recursively,so as to obtain the high order compact schemes formally.Moreover,the schemes can be implemented efficiently by solving a series of tridiagonal systems recursively or the fast Fourier transform(FFT).With mathematical induction,the eigenvalues of the proposed differencing operators are shown to be bounded away from zero,which indicates the positive definiteness of the operators.To obtain numerical boundary conditions for the high order schemes,the simplified inverse Lax-Wendroff(SILW)procedure is adopted and the stability analysis is performed by the Godunov-Ryabenkii method and the eigenvalue spectrum visualization method.Various numerical experiments are provided to demonstrate the effectiveness and robustness of our algorithms.

High Order IMEX Stochastic Galerkin Schemes for Linear Transport Equation with Random Inputs and Diffusive Scalings

In this paper,we consider the high order method for solving the linear transport equations under diffusive scaling and with random inputs.To tackle the randomness in the problem,the stochastic Galerkin method of the generalized polynomial chaos approach has been employed.Besides,the high order implicit-explicit scheme under the micro-macro decomposition framework and the discontinuous Galerkin method have been employed.We provide several numerical experiments to validate the accuracy and the stochastic asymptotic-preserving property.

A New Double Layer Multi-Secret Sharing Scheme

Cryptography is deemed to be the optimum strategy to secure the data privacy in which the data is encoded ahead of time before sharing it.Visual Secret Sharing(VSS)is an encryption method in which the secret message is split into at least two trivial images called’shares’to cover it.However,such message are always targeted by hackers or dishonest members who attempt to decrypt the message.This can be avoided by not uncovering the secret message without the universal share when it is presented and is typically taken care of,by the trusted party.Hence,in this paper,an optimal and secure double-layered secret image sharing scheme is proposed.The proposed share creation process contains two layers such as threshold-based secret sharing in the first layer and universal share based secret sharing in the second layer.In first layer,Genetic Algorithm(GA)is applied to find the optimal threshold value based on the randomness of the created shares.Then,in the second layer,a novel design of universal share-based secret share creation method is proposed.Finally,Opposition Whale Optimization Algorithm(OWOA)-based optimal key was generated for rectange block cipher to secure each share.This helped in producing high quality reconstruction images.The researcher achieved average experimental outcomes in terms of PSNR and MSE values equal to 55.154225 and 0.79365625 respectively.The average PSNRwas less(49.134475)and average MSE was high(1)in case of existing methods.

Impacts of Water-Sediment Regulation Scheme on Chromophoric Dissolved Organic Matter in the Lower Yellow River

As a river with more than 3000 reservoirs in its watershed,the Yellow River has been affected by dams not only on the sediment load,but also on the water quality.Water-sediment regulation scheme(WSRS),which has been carried out annually in the Yellow River since 2002,is a typical human activity affecting river water quality.Chromophoric dissolved organic matter(CDOM)in river is susceptible to changes in ecological and environmental conditions as well as human activities.Here,we report variations in dissolved organic carbon concentrations,compositions and sources of CDOM in time series samples in the lower Yellow River during WSRS.In addition,a parallel factor fluorescence analysis(PARAFAC)method is applied to identify different fluorescent components in water samples during WRSR,showing four major components including tryptophan-like component(C1),microbial humic-like component(C2),terrestrial humic-like component(C3)and tyrosine-like component(C4).In general,C1 increased after water regulation,while C2 and C3 increased after sediment regulation,indicating that the water and sediment released by the dam have different effects on CDOM compositions.Under the impacts of the dam,source of CDOM in the lower Yellow River is mainly autochthonous related to microbial activities,and is regulated by the terrestrial input during WSRS period.Sediment resuspension inhibits microbial activities and reduces the production of autochthonous CDOM.Overall,human activities especially WSRS,as exemplified here,significantly alter the quality and quantity of CDOM in the lower Yellow River,affecting CDOM dynamics and biogeochemical processes in the estuarine environment.

Crank-Nicolson Quasi-Compact Scheme for the Nonlinear Two-Sided Spatial Fractional Advection-Diffusion Equations

The higher-order numerical scheme of nonlinear advection-diffusion equations is studied in this article, where the space fractional derivatives are evaluated by using weighted and shifted Grünwald difference operators and combining the compact technique, in the time direction is discretized by the Crank-Nicolson method. Through the energy method, the stability and convergence of the numerical scheme in the sense of L2-norm are proved, and the convergence order is . Some examples are given to show that our numerical scheme is effective.

Sparse-Grid Implementation of Fixed-Point Fast Sweeping WENO Schemes for Eikonal Equations

Fixed-point fast sweeping methods are a class of explicit iterative methods developed in the literature to efficiently solve steady-state solutions of hyperbolic partial differential equations(PDEs).As other types of fast sweeping schemes,fixed-point fast sweeping methods use the Gauss-Seidel iterations and alternating sweeping strategy to cover characteristics of hyperbolic PDEs in a certain direction simultaneously in each sweeping order.The resulting iterative schemes have a fast convergence rate to steady-state solutions.Moreover,an advantage of fixed-point fast sweeping methods over other types of fast sweeping methods is that they are explicit and do not involve the inverse operation of any nonlinear local system.Hence,they are robust and flexible,and have been combined with high-order accurate weighted essentially non-oscillatory(WENO)schemes to solve various hyperbolic PDEs in the literature.For multidimensional nonlinear problems,high-order fixed-point fast sweeping WENO methods still require quite a large amount of computational costs.In this technical note,we apply sparse-grid techniques,an effective approximation tool for multidimensional problems,to fixed-point fast sweeping WENO methods for reducing their computational costs.Here,we focus on fixed-point fast sweeping WENO schemes with third-order accuracy(Zhang et al.2006[41]),for solving Eikonal equations,an important class of static Hamilton-Jacobi(H-J)equations.Numerical experiments on solving multidimensional Eikonal equations and a more general static H-J equation are performed to show that the sparse-grid computations of the fixed-point fast sweeping WENO schemes achieve large savings of CPU times on refined meshes,and at the same time maintain comparable accuracy and resolution with those on corresponding regular single grids.

Analysis and Comparison of Slope-cutting Widening Schemes in Highway Reconstruction and Expansion Project Based on MIDAS Software

In this paper,the geological condition of the right-side slope of the K114+694–K115+162 section of Yong-tai-wen Expressway is investigated and analyzed with the results showing that the strength of rock mass is the main contributor to the stability of the slope.Then,two widening schemes are proposed,which are the steep slope with strong support and the gentle slope with general support schemes.The static/slope module of MIDAS GTS finite element analysis software and the strength reduction method were used to compare the two schemes.The results show that the steep slope with a strong support scheme has obvious advantages in land requisition,environmental protection,and safety and is more suitable for reconstructing and expanding the highway slope.

WTO/SPS通报

根据《实施卫生与植物卫生措施协定》(Agreementon the Application of Sanitary and Phytosanitary Measures,简称《SPS协定》)中的透明度原则,成员应保证迅速公布所有拟采用的但尚没有对应的国际标准、指南或建议或与其在内容实质上不同的,且可能对其他成员贸易产生重大影响的卫生与植物卫生措施,以使利益相关方知晓。通报统计分析1.通报数量2024年2月,共有31个国家或组织向WTO秘书处发送170件SPS通报,提交通报数量位列前十位的国家或组织依次是:巴西(26件)、欧盟(26件)、乌干达(16件)、新西兰(12件)、泰国(12件)、哈萨克斯坦(7件)、坦桑尼亚(6件)、加拿大(5件)、沙特阿拉伯(5件)和土耳其(5件)。

WTO/SPS通报

根据《实施卫生与植物卫生措施协定》(Agreementon the Application of Sanitary and Phytosanitary Measures,简称《SPS协定》)中的透明度原则,成员应保证迅速公布所有拟采用的但尚没有对应的国际标准、指南或建议或与其在内容实质上不同的,且可能对其他成员贸易产生重大影响的卫生与植物卫生措施,以使利益相关方知晓。

WTO/SPS通报

根据《实施卫生与植物卫生措施协定》(Agreementon the Application of Sanitary and Phytosanitary Measures,简称《SPS协定》)中的透明度原则,成员应保证迅速公布所有拟采用的但尚没有对应的国际标准、指南或建议或与其在内容实质上不同的,且可能对其他成员贸易产生重大影响的卫生与植物卫生措施,以使利益相关方知晓。

WTO/SPS通报

根据《实施卫生与植物卫生措施协定》(Agreementon the Application of Sanitary and Phytosanitary Measures,简称《SPS协定》)中的透明度原则,成员应保证迅速公布所有拟采用的但尚没有对应的国际标准、指南或建议或与其在内容实质上不同的,且可能对其他成员贸易产生重大影响的卫生与植物卫生措施,以使利益相关方知晓。

WTO/SPS通报

根据《实施卫生与植物卫生措施协定》(Agreementon the Application of Sanitary and Phytosanitary Measures,简称《SPS协定》)中的透明度原则,成员应保证迅速公布所有拟采用的但尚没有对应的国际标准、指南或建议或与其在内容实质上不同的,且可能对其他成员贸易产生重大影响的卫生与植物卫生措施,以使利益相关方知晓。

SPS壁垒措施影响几何

研究和理解SPS措施的应用价值和发展趋势,积极应对我国农产品对外贸易中遭受的SPS措施,对于推动农业发展、维护农业安全有重要意义。随着经济全球化与国际贸易的发展,世贸组织(WTO)于乌拉圭回合谈判中全面削减关税税种及税率。在此背景下,传统的贸易壁垒逐渐削弱,而非关税贸易壁垒的影响愈发显著。《关贸总协定》(GATT)和《技术性贸易壁垒协定》(TBT协定)对卫生和植物检疫没有足够的约束力,要求也不具体,因此在乌拉圭回合谈判中,许多国家提议制定SPS(实施卫生与植物检疫措施)协定。