Establishment of a Geometric Geoid Model and Evaluation of the EGM2008 and EIGEN-6CA Models over the Dakar-Thies-Mbour Triangle in Senegal

High-accuracy geoid determination is an essential goal that many groups of scientists and countries are striving to achieve. Techniques for determining geoid models have evolved over time. Unfortunately, this all-important determination requires relatively substantial technical and financial resources, depending on the type of geoid to be determined. This situation justifies the inadequacy, and sometimes absence, of accurate geoid models in many countries, despite the new challenges of altimetric positioning using space or satellite positioning techniques. This study focuses on the establishment of a geometric geoid model using simplistic techniques that are accessible and applicable in restricted or wide areas, with or without gravimetric data. The study was applied to the Dakar-Thiès-Mbour triangle, the two regions in the extreme west of Senegal that are home to the most infrastructure projects with the highest socio-economic stakes, as well as mines currently being exploited, and therefore the highest stakes in terms of positioning. This study also enabled us to assess the accuracy of a number of global field models in Senegal, which are used by some professionals for altimetric positioning using Global Positioning Satellite Systems (GNSS) in the absence of a local geoid model. The estimated geoid model is based on the determination of undulation at various sample points in the study area. To this end, a campaign of GNSS observations and direct levelling was carried out on the various points spread across the study area. These measurements were then used to determine the undulation at each point. Bilinear interpolation was used to deduce the undulations throughout the study area, based on the altimeter conversion grid. This grid was evaluated using GPS/level control points.

Genome-edited rabbits:Unleashing the potential of a promising experimental animal model across diverse diseases

Animal models are extensively used in all aspects of biomedical research,with substantial contributions to our understanding of diseases,the development of pharmaceuticals,and the exploration of gene functions.The field of genome modification in rabbits has progressed slowly.However,recent advancements,particularly in CRISPR/Cas9-related technologies,have catalyzed the successful development of various genome-edited rabbit models to mimic diverse diseases,including cardiovascular disorders,immunodeficiencies,agingrelated ailments,neurological diseases,and ophthalmic pathologies.These models hold great promise in advancing biomedical research due to their closer physiological and biochemical resemblance to humans compared to mice.This review aims to summarize the novel gene-editing approaches currently available for rabbits and present the applications and prospects of such models in biomedicine,underscoring their impact and future potential in translational medicine.

Genome engineering and disease modeling via programmable nucleases for insulin gene therapy;promises of CRISPR/Cas9 technology

Targeted genome editing is a continually evolving technology employing programmable nucleases to specifically change,insert,or remove a genomic sequence of interest.These advanced molecular tools include meganucleases,zinc finger nucleases,transcription activator-like effector nucleases and RNA-guided engineered nucleases(RGENs),which create double-strand breaks at specific target sites in the genome,and repair DNA either by homologous recombination in the presence of donor DNA or via the error-prone non-homologous end-joining mechanism.A recently discovered group of RGENs known as CRISPR/Cas9 gene-editing systems allowed precise genome manipulation revealing a causal association between disease genotype and phenotype,without the need for the reengineering of the specific enzyme when targeting different sequences.CRISPR/Cas9 has been successfully employed as an ex vivo gene-editing tool in embryonic stem cells and patient-derived stem cells to understand pancreatic beta-cell development and function.RNA-guided nucleases also open the way for the generation of novel animal models for diabetes and allow testing the efficiency of various therapeutic approaches in diabetes,as summarized and exemplified in this manuscript.

The simulation of LUCC based on Logistic-CA-Markov model in Qilian Mountain area, China

The Qilian mountain area was examined for using the Logistic-CA-Markov coupling model combined with GIS spatial analyst technology to research the transformation of LUCC, driving force system and simulate future tendency of variation. Results show that： （1） Woodland area decreased by 12.55%, while grassland, cultivated land, and settlement areas increased by 0.22%, 7.92%, and 0.03%, respectively, from 1986 to 2014. During the period of 1986 to 2000, forest degradation in the middle section of the mountain area decreased by 1,501.69 km2. Vegetation cover area improved, with a net increase of grassland area of 38.12 km2 from 2000 to 2014. （2） For constructing the system driving force, the best simulation scale was 210m×210m. Based on logistic regression analysis, the contribution （weight） of composite driving forces to land use and cover change was obtained, and the weight value was more objectively compared with AHP and MCE method. （3） In the natural scenarios, it is predicted that land use and cover distribution maps of Qilian mountain area in 2028 and 2042, and the Lee-Sallee index test was adopted. Over the next 27 years （2015-2042）, farmland, woodland, grassland, settlement areas show an increasing trend, especially settlements with an obvious change of 0.56%. The area of bare land will decrease by 0.89%. Without environmental degradation, tremendous structural change of LUCC will not occur, and typical characteristic of the vertical zone of the mountain would remain. Farmland and settlement areas will increase, but only in the vicinity of Qilian and Sunan counties.

A Hopfield-like hippocampal CA3 neural network model for studying associative memory in Alzheimer's disease

Associative memory, one of the major cognitive functions in the hippocampal CA3 region, includes auto-associative memory and hetero-associative memory. Many previous studies have shown that Alzheimer＇s disease （AD） can lead to loss of functional synapses in the central nervous system, and associative memory functions in patients with AD are often impaired, but few studies have addressed the effect of AD on hetero-associative memory in the hippocampal CA3 region. In this study, based on a simplified anatomical structure and synaptic connections in the hippocampal CA3 region, a three-layered Hopfield-like neural network model of hippocampal CA3 was proposed and then used to simulate associative memory functions in three circumstances： normal, synaptic deletion and synaptic compensation, according to Ruppin＇s synaptic deletion and compensation theory. The influences of AD on hetero-associative memory were further analyzed. The simulated results showed that the established three-layered Hopfield-like neural network model of hippocampal CA3 has both auto-associative and hetero-associative memory functions. With increasing synaptic deletion level, both associative memory functions were gradually impaired and the mean firing rates of the neurons within the network model were decreased. With gradual increasing synaptic compensation, the associative memory functions of the network were improved and the mean firing rates were increased. The simulated results suggest that the Hopfield-like neural network model can effectively simulate both associative memory functions of the hippocampal CA3 region. Synaptic deletion affects both auto-associative and hetero-associative memory functions in the hippocampal CA3 region, and can also result in memory dysfunction. To some extent, synaptic compensation measures can offset two kinds of associative memory dysfunction caused by synaptic deletion in the hippocampal CA3 area.

A mathematical model for ATP-mediated calcium dynamics in vascular endothelial cells induced by fluid shear stress

In consideration of the mechanism for shear-stress-induced Ca^2＋ influx via ATP（adenosine triphosphate）-gated ion channel P2X4 in vascular endothelial cells, a modified model is proposed to describe the shear-stress-induced Ca^2＋ influx. It is affected both by the Ca^2＋ gradient across the cell membrane and extracellular ATP concentration on the cell surface. Meanwhile, a new static ATP release model is constructed by using published experimental data. Combining the modified intracellular calcium dynamics model with the new ATP release model, we establish a nonlinear Ca^2＋ dynamic system in vascular endothelial cells. The ATP-mediated calcium response in vascular endothelial cells subjected to shear stresses is analyzed by solving the governing equations of the integrated dynamic system. Numerical results show that the shear-stress-induced calcium response predicted by the proposed model is more consistent with the experimental observations than that predicted by existing models.

CAS6与IAS38的对比研究

知识经济高速发展的时代,无形资产在企业总资产中所占的比重日益增加,在企业发展过程中的作用越来越大,精准提供企业无形资产相关会计信息将有利于信息使用者做出正确决策。通过对我国《企业会计准则第6号——无形资产》与《国际会计准则第38号——无形资产》的比较,发现两者在无形资产的确认、计量和披露等方面仍存在一些差异。为此,结合我国国情提出了扩大无形资产的界定范围、合理采用多种计量方法等措施,以期进一步完善我国无形资产会计准则,提高会计信息质量和国际化水平。

基于1D-CNN的无砟轨道CA砂浆脱空识别

为解决水泥乳化沥青砂浆(CA砂浆)脱空位置识别的难题,提出考虑CA砂浆脱空的无砟轨道模型建模与计算方案。首先,基于CRTS I型板式无砟轨道“梁-板-板”建模理论,使用非线性弹簧模拟CA砂浆脱空病害,输入扣件支点反力作为模型的激励,得到监测点位的垂向加速度数据集。其次,通过对数据集缩放、添加噪声的方式进行数据增强,增强数据集的差异,以增强识别模型的泛化性,获得更加准确的识别结果。最后,建立脱空病害的识别方法,搭建一维卷积神经网络(1D-CNN)进行CA砂浆的脱空位置识别,构建准确率、查准率和查全率等评价指标评估识别结果,使用t-SNE降维算法对结果进行可视化。对比其他3种神经网络的表现,探讨1D-CNN应用于CA砂浆脱空位置识别的优势。研究结果表明:“梁-板-板”模型反映了无砟轨道的力学本征,用于CA砂浆脱空问题的仿真模拟是可行的;通过对数据集信号缩放、添加噪声的方式进行数据增强可提高深度学习模型的性能;从深度学习的角度来看,CA砂浆脱空发生在板中造成的危害较小,应重点关注板端CA砂浆脱空的养护与维修问题;1D-CNN相比其他3种模型运算时间短,在CA砂浆脱空位置识别数据集上优势更大,识别准确率可达95%以上。研究结果为进一步提高无砟轨道结构监测的自动化和智能化水平提供参考。

CA推出数据建模专利技术的Allfusion Modeling Suite新版本

本刊讯5月22日，CA宣布推出新版本的AllFusion Modeling Suite建模工具，在功能强大的AllFusion Erwin Data Modeler内嵌具有专利的通用的数据建模引擎。通过简化复杂数据库应用的设计、实施和分析，AllFusion Modeling Suite r7将帮助IT部门加快应用交付、提升员工生产力及控制数据库的拥有成本。同时，它还可提供全面的数据库及数据仓库变化的审计记录，促进公司遵从法规并迅速发现问题。

改进CA-Markov模型的城市土地空间结构演变预测

城市土地空间结构演变预测需要大量的数据支持,现阶段预测手段存在预测精度不佳的问题,为此提出GIS技术下城市土地空间结构演变预测方法。通过GIS技术获取城市土地空间结构数据,并对其进行结构演变分析;通过人工神经网络模型、轮盘竞争机制和惯性系数对CA模型实行优化处理;将改进CA模型与Markov结构结合,建立改进CA-Markov模型,根据城市土地空间结构演变分析结果实现城市土地空间结构演变预测。实验结果表明,所提方法的城市土地空间结构演变预测精度更高,整体应用效果更好。

基于InVEST与CA-Markov模型的宝鸡市碳储量时空演变与预测

土地利用类型的变化是影响陆地生态系统碳储量变化的重要因素,分析区域未来土地利用格局对碳储量的影响、对维持碳平衡具有重要意义.基于宝鸡市2000—2020年土地利用数据,运用InVEST模型和CA-Markov模型,对2000—2020年宝鸡市不同土地利用类型碳储量的变化特征进行分析,并对2030年不同情景下宝鸡市土地利用变化及碳储量变化情况进行了预测.研究表明:①2000—2020年宝鸡市建设用地面积不断增加,耕地、林地和草地为主要土地利用类型.②2000—2020年,宝鸡市碳储量共损失0.42×10^(6)t,耕地和林地面积减少是其碳储量减少的主要原因.③2020—2030年自然发展情景下宝鸡市碳储量损失最多,耕地保护情景和生态保护情景下宝鸡市碳储量相差不大,控制城市扩张情景下宝鸡市碳储量损失最少、固碳能力最强.因此,未来进行国土空间规划时,可统筹考虑控制城市扩张情景、生态保护情景和耕地保护情景,以确保在粮食供给和生态安全的基础上,提高研究区的碳储量.

基于动态稳定性验证和CA-Markov预测的耕地时空演变特征--以赣榆区为例

为阐明耕地变化动态稳定性验证的重要性,预测“十四五”目标年(2025年)与远景目标年(2035年)的耕地变化,本研究运用耕地面积变异系数、地理集中指数、不平衡指数及趋势分析法,从耕地数量、空间分布与空间发展趋势三个方面,对江苏省连云港市赣榆区耕地变化的动态稳定性进行验证,并运用CA-Markov模型对未来不同政策情境下的耕地变化情况进行模拟。结果表明,2009-2016年赣榆区耕地总量持续下降,未存在较大反复与波动,耕地空间分布较为均衡,耕地占用与补充的空间发展趋势较为连续,总体上具有较高的动态稳定性,符合运用CA-Markov模型的前提条件。预测在各种政策情境下,2025年之前赣榆区将经历快速的耕地非农化过程,至2035年耕地减少的速率有所放缓,具有区位优势的赣榆北部地区将是未来耕地非农化的重点区域,耕地将逐渐向南部内陆地区转移。研究表明,对耕地变化的动态稳定性进行验证可以有效保证CA-Markov模型的模拟精度,赣榆区未来的耕地保护形势不容乐观,应合理协调经济发展与耕地保护之间的关系,保障社会、生态与粮食安全。

Modeling walking behavior of pedestrian groups with floor field cellular automaton approach

Walking in groups is very common in a realistic walking environment. An extended floor field cellular automaton （CA） model is therefore proposed to describe the walking behavior of pedestrian groups, This model represents the motion of pedestrian groups in a realistic way. The simulation results reveal that the walking behavior of groups has an important but negative influence on pedestrian flow dynamics, especially when the density is at a high level. The presence of pedestrian groups retards the emergence of lane formation and increases the instability of operation of pedestrian flow. Moreover, the average velocity and volume of pedestrian flow are significantly reduced due to the group motion. Meanwhile, the parameter-sensitive analysis suggests that pedestrian groups should make a compromise between efficient movement and staying coherent with a certain spatial structure when walking in a dense crowd.

农业企业生物资产会计核算的完善——基于CAS5与IAS41的比较

促进农业农村高质量发展是我国“十四五”期间“三农”发展的主要基调,农业行业的企业化管理是未来集约资源的重要途径,而生物资产规范难、核查难一直以来成为农业企业信贷融资乃至IPO的天然障碍,一定程度上限制农业企业融资渠道和发展规模。从会计核算层面完善农业企业生物资产业务,应当深度明晰各类生物资产内涵,强制要求在资产负债表中将生物资产按类别单独列报,逐步扩大生物资产公允价值计量范围,提高生物资产披露在企业信息披露评级中的权重。

The big bang of genome editing technology: development and application of the CRISPR/Cas9 system in disease animal models

Targeted genome editing technology has been widely used in biomedical studies. The CRISPR- associated RNA-guided endonuclease Cas9 has become a versatile genome editing tool. The CRISPR/Cas9 system is useful for studying gene function through efficient knock-out, knock-in or chromatin modification of the targeted gene loci in various cell types and organisms. It can be applied in a number of fields, such as genetic breeding, disease treatment and gene functional investigation In this review, we introduce the most recent developments and applications, the challenges, and future directions of Cas9 in generating disease animal model. Derived from the CRISPR adaptive immune system of bacteria, the development trend of Cas9 will inevitably fuel the vital applications from basic research to biotechnology and bio- medicine.

Modeling Microstructural Evolution under the Influence of Thermosolutal Convection during Ingot Solidification Process

A model combined both macroscopic transport and microstructural evolution is applied to describe the influence of thermosolutal convection on microstructural evolution during the solidification process. Firstly, the volume average method and Simpler algorithm are used to solve the macroscopic transport equation. Then the calculated results are incorporated into the cellular automaton (CA) model to simulate the microstructural evolution. Using this model, a simple casting ingot is applied to simulate microstructural evolution. Through the simulation, it is found that the thermosolutal convection has a strong influence on the redistribution of temperature field and solute field, which influence the solidification microstructural evolution.

东北地区土地覆被格局变化模拟:基于CLUE-S和Markov-CA模型的对比分析

研究以遥感解译的东北地区2000年、2010年、2015年的土地覆被变化为基础,充分考虑自然和社会因素对土地覆被变化的影响,分别通过CLUE-S模型和Markov-CA模型对东北地区2015年和2030年土地覆被格局进行模拟,研究结果表明:通过与遥感解译的2015年实际土地覆被类型数据对比验证,CLUE-S模型和Markov-CA模型模拟结果的总体Kappa指数分别为0.9700和0.9649,结果表明2种模型的模拟结果较为理想,CLUE-S模型的模拟精度较Markov-CA模型更高。2015—2030年东北地区草地、耕地、湿地、其他用地和水体面积呈现下降趋势,林地、人工表面面积呈现增加趋势,人地关系越发紧张。东北地区作为生态环境相对脆弱的区域需警惕不可持续的土地覆被变化,需权衡生态保护、粮食增加与基础设施建设的用地需求和协调发展。

Transmission Capacity Analysis for Linear VANET under Physical Model

In this study, the transmission capacity of VANETs in a highway scenario is analysed on the basis of a 1D line model and the carrier sense multiple access with collision avoidance(CSMA/CA) protocol. We describe the CSMA/CA protocol used in IEEE802.11 p from the perspective of the geometric relationship amongst simultaneous transmitters. The desired channel and interfering channels are assumed to experience the same amount of path-loss and Rayleigh fading. On the basis of the proposed model, we analyse the attempted transmission probability of each road segment and the maximum intensity of active transmitters, including their theoretical values. Then, we employ the physical model to obtain the outage probability and derive the upper bound of the transmission capacity of a VANET, which is defined as the average spatial density of successful transmissions in the network. Simulation results indicate that the theoretical value offers a good bound on network capacity.

CAS3与IAS40的对比研究

文章通过对我国《企业会计准则第3号--投资性房地产》(CAS 3)与《国际会计准则第40号--投资性房地产》(IAS 40)中有关投资性房地产的定义、范围、计量、转换、处置和披露等方面的比较,发现我国会计准则存在对投资性房地产的界定范围相对较窄、公允价值计量的估值技术不够规范、信息披露内容不够充分等问题。为此,从放宽投资性房地产界定范围、改进公允价值估值技术、丰富信息披露的内容等三个方面提出了改进建议。