Spatio-temporal differentiation of landscape ecological niche in western ecological frangible region： A case study of Yan＇an region in northwestern China

In this study, we attempt to put forward a conception of landscape ecological niche, enlightened by international scholars on extending the ecological niche theory from spatial niche to functional niche. That is helpful for comprehensively appraising landscape spatial patterns and ecological functions, also, presents a new method for analyzing landscape features from multidimensional aspects. The practice process is demonstrated by taking Yan＇an region in northwestern China as a case. Firstly, the indices system including spatial attribute and functional attribute is established for assessing landscape ecological niche. Additionally, two-dimensional figures are drawn for comparing the spatio-temporal features of landscape ecological niche in 1987 and 2000 among the 13 administrative counties. The results show that from 1987 to 2000, towards Yan＇an region, spatial attribute value of landscape ecological niche changes from 1.000 to 1.178 with an obvious increment, and functional attribute value changes from 0.989 to 1.069 with a little increment, both of which enhance the regional landscape ecological niche. Towards each county, spatial attribute value of landscape ecological niche increases to different extent while functional attribute value changes dissimilarly with an increment or a decrement.

The Research of Galanz＇s Niche Strategy

Niche strategy is one of the competitive strategies based on a small market, and an enterprise enters the market and becomes the leader of the market in the end. Galanz is a typical Chinese manufacturer to execute niche strategy. It makes use of labour force advantage, resource advantage and technologist advantage to enter microwave oven market, and it has been one of the most famous manufacture factories in the world. The success of Galanz gives elicitations to other Chinese manufacturers, and it will inspirit more and more manufacturers appear similar as Galanz.

Ecological Niche Divergence between Trapelus ruderatus(Olivier,1807)and T.persicus(Blanford,1881)(Sauria:Agamidae)in the Middle East

Modeling the potential distribution areas for a given species is important in understanding the relationship between the actual distribution and the most suitable habitat for a species. In this study, we obtained all available records of Trapelus ruderatus and Trapelus persicus from museums, literature and fieldwork and used them with environmental layers in the Maximum Entropy algorithm to predict highly suitable habitat areas. The distribution model of T. ruderatus and T. persicus showed excellent performance for both models （T. ruderatus AUC = 0.964 ± 0.001 and T. persicus AUC = 0.996 ± 0.003）, and predicted suitable regions in Iran, Turkey, Iraq and Syria. Niche overlap was measured between the two groups by ENMtools and 13% overlapped. We used a niche identity test to determine differences between the niches of the two species. Finally, by comparing our null hypothesis to the true niche overlap of the two species, we were able to reject our null hypothesis of no difference between the niches. Due to the sympatric distribution pattern of these species, we do not need a background test for niche divergence.

干细胞niche与心肌细胞分化的调控机制研究

干细胞是一类具有自我更新和多向分化潜能的特殊细胞。研究发现,干细胞的生物学行为高度依赖于其所处的微环境(niche)。Niche对干细胞的作用分为细胞与细胞之间的直接作用和基质及众多细胞因子对干细胞的间接作用,涉及多条信号转导通路及其相互作用。本文主要介绍骨髓干细胞的niche对间充质干细胞(MSC)的调控,并探讨MSC向心肌细胞分化的调控机制。

Equilibrium Strategy of the Pursuit-Evasion Game in Three-Dimensional Space

The pursuit-evasion game models the strategic interaction among players, attracting attention in many realistic scenarios, such as missile guidance, unmanned aerial vehicles, and target defense. Existing studies mainly concentrate on the cooperative pursuit of multiple players in two-dimensional pursuit-evasion games. However, these approaches can hardly be applied to practical situations where players usually move in three-dimensional space with a three-degree-of-freedom control. In this paper,we make the first attempt to investigate the equilibrium strategy of the realistic pursuit-evasion game, in which the pursuer follows a three-degree-of-freedom control, and the evader moves freely. First, we describe the pursuer's three-degree-of-freedom control and the evader's relative coordinate. We then rigorously derive the equilibrium strategy by solving the retrogressive path equation according to the Hamilton-Jacobi-Bellman-Isaacs(HJBI) method, which divides the pursuit-evasion process into the navigation and acceleration phases. Besides, we analyze the maximum allowable speed for the pursuer to capture the evader successfully and provide the strategy with which the evader can escape when the pursuer's speed exceeds the threshold. We further conduct comparison tests with various unilateral deviations to verify that the proposed strategy forms a Nash equilibrium.

Proportion Integration Differentiation(PID)Control Strategy of Belt Sander Based on Fuzzy Algorithm

Aiming at solving the problems of response lag and lack of precision and stability in constant grinding force control of industrial robot belts,a constant force control strategy combining fuzzy control and proportion integration differentiation(PID)was proposed by analyzing the signal transmission process and the dynamic characteristics of the grinding mechanism.The simulation results showed that compared with the classical PID control strategy,the system adjustment time was shortened by 98.7%,the overshoot was reduced by 5.1%,and the control error was 0.2%-0.5%when the system was stabilized.The optimized fuzzy control system had fast adjustment speeds,precise force control and stability.The experimental analysis of the surface morphology of the machined blade was carried out by the industrial robot abrasive grinding mechanism,and the correctness of the theoretical analysis and the effectiveness of the control strategy were verified.

Uniform Pricing Strategy vs. Price Differentiation Strategy in the Presence of Cost Saving and Demand Increasing

Price differentiation or discrimination strategy has been regarded as the best choice for firms with online and offline channels, however, recent years often witnessed the practices of the uniform pricing strategy. This paper aims to address the question whether the uniform pricing strategy may be better for the manufacturer, when the uniform pricing strategy has a positive impact on increasing the ciistomer demand and reducing the operations cost. The research shows that the uniform pricing strategy can be bet ter than the price differentiation strategy when the cost saving and demand increasing are large enough or the consumers' acceptance of online channel lies in a certain interval. Moreover, the manufac tu rers or brand owners need a tradeoff bet ween the benefit from online channel and the negative impact from the offline channel when they implement the price differentiation strategy. Finally, the authors obtain some managerial insights and implications based on the numerical analyses, which are in line with the phenomena in practice.

Glypican 4 down-regulation in pluripotent stem cells as a potential strategy to improve differentiation and to impair tumorigenicity of cell transplants

Recent advances in stem cell technologies have opened new avenues for the treatment of a number of diseases still lacking effective therapeutic options.Cell transplantation has emerged as among the most promising clinical intervention for disorders such as injuries,diabetes,liver diseases, neurodegeneration and heart failure （Lee et al., 2013; Forbes and Rosenthal, 2014; Tabar and Studer, 2014）.

Metabolic and proteostatic differences in quiescent and active neural stem cells

Adult neural stem cells are neurogenesis progenitor cells that play an important role in neurogenesis.Therefore,neural regeneration may be a promising target for treatment of many neurological illnesses.The regenerative capacity of adult neural stem cells can be chara cterized by two states:quiescent and active.Quiescent adult neural stem cells are more stable and guarantee the quantity and quality of the adult neural stem cell pool.Active adult neural stem cells are chara cterized by rapid proliferation and differentiation into neurons which allow for integration into neural circuits.This review focuses on diffe rences between quiescent and active adult neural stem cells in nutrition metabolism and protein homeostasis.Furthermore,we discuss the physiological significance and underlying advantages of these diffe rences.Due to the limited number of adult neural stem cells studies,we refe rred to studies of embryonic adult neural stem cells or non-mammalian adult neural stem cells to evaluate specific mechanisms.

精原干细胞niche的研究进展

精原干细胞(spermatogonial stem cells,SSCs)是指睾丸内位于曲精细管基膜上既能自我更新维持自身适量恒定,又能定向分化产生精母细胞的一类原始精原细胞。随着干细胞深入的研究,人们发现了一种控制着干细胞可塑性与命运的微环境,此微环境被称为干细胞niche,干细胞niche由niche细胞、细胞外基质、细胞因子等构成。精原干细胞niche是由黏附因子、生长因子、支持细胞、间质细胞以及小管周肌肉细胞组成。大量的研究表明支持细胞在睾丸中是主要的成体细胞,通过分泌可溶性的因子来影响精原干细胞niche的结构与功能,同时支持细胞还能够间接的影响其他的成体细胞。随着年龄的增长使得精原干细胞niche的功能下降。精原干细胞数量以及精原干细胞niche为我们研究组织特异性干细胞生物学以及保持再生组织平衡提供了很宝贵的线索,精原干细胞对于保持组织的自我更新具有很重要的作用,并且受到人们大量的关注,然而精原干细胞niche也起到很重要的作用,它为治疗一些疾病提供新途径.本文将综述精原干细胞niche及其变化对精原干细胞功能调节的相关研究进展。

基于等效序阻抗差异特征的低频输电线路差动保护优化方案

低频输电线路故障时,两侧短路电流均由模块化多电平矩阵变换器提供,两侧短路电流相角均受控且幅值相当,导致差动保护灵敏度严重下降。分析了低频输电系统定电压控制侧和功率控制侧的等效正、负序阻抗特征,指出因控制策略不同,系统故障时两侧等效正、负序阻抗特征存在明显差异。分析了低频输电线路区内和区外故障两侧保护装置测量到的等效序阻抗之间的差异性和相似性,基于此特征构建了两侧等效序阻抗差异指标,提出了基于等效序阻抗差异指标的差动保护制动系数优化方法。仿真结果表明,所提方案能够显著提升低频输电线路区内故障时差动保护的动作速度和动作灵敏性。

依托生态位战略的国产工业软件发展

工业软件被称为工业制造的大脑与神经,然而由于欧美软件占据市场主导地位,工业软件成为我国工业行业中的弱势领域。生态位战略立足国产工业软件行业现状,有助于企业厘清市场竞争法则,选择合适的生存战略。借鉴生态位理论,依托企业生态位重叠度、生态位宽度的内涵,对减轻国产工业软件的竞争压力作出尝试性探索。并通过创元对北仑模具行业进行数字化改造的案例,对我国工业软件的生态位发展策略进行适用性分析。该研究可为国产工业软件企业提供借鉴参考,使其找准发展空间,推动国产工业软件持续健康发展。

In situ forming injectable MSC-loaded GelMA hydrogels combined with PD for vascularized sweat gland regeneration

Dear Editor,Three dimensional(3D)bioprinted extracellular matrix(ECM)can be used to provide both biochemical and biophysical cues to direct mesenchymal stem cells(MSCs)differentiation,and then differentiated cells were isolated for implantation in vivo using surgical procedures.However,the reduced cell activity after cell isolation from 3D constructs and low cell retention in injured sites limit its application[1].Methacrylated gelatin(GelMA)hydrogel has the advantage of fast crosslinking,which could resemble complex architectures of tissue construct in vivo[2].Here,we adopted a noninvasive bioprinting procedure to imitate the regenerative microenvironment that could simultaneously direct the sweat gland(SG)and vascular differentiation from MSCs and ultimately promote the replacement of glandular tissue in situ(Fig.1a).

Unveiling the role of hypoxia-inducible factor 2alpha in osteoporosis:Implications for bone health

BACKGROUND Osteoporosis(OP)has become a major public health problem worldwide.Most OP treatments are based on the inhibition of bone resorption,and it is necessary to identify additional treatments aimed at enhancing osteogenesis.In the bone marrow(BM)niche,bone mesenchymal stem cells(BMSCs)are exposed to a hypoxic environment.Recently,a few studies have demonstrated that hypoxiainducible factor 2alpha(HIF-2α)is involved in BMSC osteogenic differentiation,but the molecular mechanism involved has not been determined.AIM To investigate the effect of HIF-2αon the osteogenic and adipogenic differentiation of BMSCs and the hematopoietic function of hematopoietic stem cells(HSCs)in the BM niche on the progression of OP.METHODS Mice with BMSC-specific HIF-2αknockout(Prx1-Cre;Hif-2αfl/fl mice)were used for in vivo experiments.Bone quantification was performed on mice of two genotypes with three interventions:Bilateral ovariectomy,semilethal irradiation,and dexamethasone treatment.Moreover,the hematopoietic function of HSCs in the BM niche was compared between the two mouse genotypes.In vitro,the HIF-2αagonist roxadustat and the HIF-2αinhibitor PT2399 were used to investigate the function of HIF-2αin BMSC osteogenic and adipogenic differentiation.Finally,we investigated the effect of HIF-2αon BMSCs via treatment with the mechanistic target of rapamycin(mTOR)agonist MHY1485 and the mTOR inhibitor rapamycin.RESULTS The quantitative index determined by microcomputed tomography indicated that the femoral bone density of Prx1-Cre;Hif-2αfl/fl mice was lower than that of Hif-2αfl/fl mice under the three intervention conditions.In vitro,Hif-2αfl/fl mouse BMSCs were cultured and treated with the HIF-2αagonist roxadustat,and after 7 d of BMSC adipogenic differentiation,the oil red O staining intensity and mRNA expression levels of adipogenesis-related genes in BMSCs treated with roxadustat were decreased;in addition,after 14 d of osteogenic differentiation,BMSCs treated with roxadustat exhibited increased expression of osteogenesis-related genes.The opposite effects were shown for mouse BMSCs treated with the HIF-2αinhibitor PT2399.The mTOR inhibitor rapamycin was used to confirm that HIF-2αregulated BMSC osteogenic and adipogenic differentiation by inhibiting the mTOR pathway.Consequently,there was no significant difference in the hematopoietic function of HSCs between Prx1-Cre;Hif-2αfl/fl and Hif-2αfl/fl mice.CONCLUSION Our study showed that inhibition of HIF-2αdecreases bone mass by inhibiting the osteogenic differentiation and increasing the adipogenic differentiation of BMSCs through inhibition of mTOR signaling in the BM niche.

高校资产配置中大型仪器论证工作研究

高校大型仪器论证工作是高校资产全生命周期流程管理的关键环节,大型仪器论证工作面临的挑战包括不同共享平台的差异化、论证内涵与实践的不协同、基础信息不完善等。该文详述了某高校论证工作的实践,包括差异化论证策略,根据经费来源进行分类和分级论证;采取多样化的论证组织形式完善论证的机制和形式。此外,该文还讨论了专家在仪器运维成本、开放共享能力方面的专业性分析建议可以指导科学规划,基于政策的合法合规性引导将直接影响大型仪器采购和管理的效率与质量,人工智能技术有助于提高基础数据的质量。

基于博弈论的弹目攻防决策方法研究

针对空战环境中弹目攻防双方的对抗特性,提出了一种基于博弈论的弹目攻防决策方法。基于导弹目标运动数学关系得到状态方程,根据弹目攻防对抗机理建立“一对一导弹-目标”动态博弈模型,确定弹目双方策略集与收益矩阵,提出混合策略纳什均衡求解方法,并结合模型滚动预测方法获得该策略空间的纳什均衡点。算例仿真结果表明,基于混合策略下导弹制导律为该策略空间的纳什均衡点,且该方法可以减小导弹对目标的脱靶量,提高导弹的命中精度,为导弹攻防作战提供了依据。

多策略改进的猎人猎物优化算法及其应用

针对猎人猎物优化算法易陷入局部最优和收敛精度不足的问题,本文提出多策略改进的猎人猎物优化算法。该算法基于动态搜索思想,通过自适应机制从全局搜索转向局部开发;通过利用种群的历史信息来实施差分进化,从而增强种群的多样性;采用精英池策略和非线性步长相结合的方法,以防止算法陷入局部最优,并提升其收敛精度。在10个大规模(10 000维)测试函数上对改进后的算法和其他6种经典或最新的优化算法进行性能评估,结果显示,该算法在全局优化能力、寻优精度和稳定性方面均表现出色,能有效解决高维优化问题。最后,将多策略改进猎人猎物优化算法应用于三维无人机路径规划问题,仿真实验结果表明,该算法能求解到最优的无人机三维规划路径。

基于量化外科护理评估策略的差异化护理模式在结直肠癌腹腔镜手术患者中的应用

目的 探究基于量化外科护理评估策略的差异化护理模式对结直肠癌腹腔镜手术患者预后恢复、并发症发生率、疼痛程度、舒适度、自护能力及生活质量的影响。方法 选取2021年2月至2022年12月于郑州大学第二附属医院就诊的102例拟接受腹腔镜根治术的结直肠患者为研究对象,按照随机数字表法分为对照组和观察组,各51例。对照组接受常规护理,观察组基于前者,接受基于量化外科护理评估策略的差异化护理模式。对比两组预后恢复情况、并发症发生情况及干预前后住院舒适状况量表(GCQ)评分、视觉模拟法(VAS)评分、自我护理能力测定量表(ESCA)评分、欧洲癌症研究与治疗组织生活质量核心问卷(EORTC QLQ-C30)评分。结果 观察组首次下床活动时间、首次进食时间、首次排气时间、首次排便时间、住院时间均短于对照组(P<0.05);观察组并发症发生率低于对照组(P<0.05);干预7 d后观察组VAS评分低于对照组(P<0.05);干预后观察组ESCA、GCQ评分高于对照组(P<0.05);干预后观察组EORTC QLQ-C30中功能领域评分、总体生活质量评分高于对照组,症状领域评分低于对照组(P<0.05)。结论 基于量化外科护理评估策略的差异化护理模式应用于腹腔镜结直肠术后患者中,可降低并发症发生风险,缓解疼痛感,增强自护能力,进而促进生活质量改善及患者病情好转。

基于生物入侵的特征选择算法

在自然界中,生物入侵以其发展的迅速和巨大的生态影响而受到关注,所引入种群对合适栖息地的寻找过程往往有其内在的逻辑,种群之间的交流和种群的扩张也在这个过程中起到了重要作用。通过探究种群对适宜栖息地的寻找原理,提出一种基于生物入侵的特征选择(BIAFS)算法。在BIAFS算法中,生物入侵过程分为种群建立、种群迁移、种群交流和扩张、种群发展4个阶段。在实验验证过程中,在9个数据集上将BIAFS算法与8种高性能算法进行实验比较。实验结果显示,BIAFS算法在7个数据集上的分类准确率(CA)和降维(DR)率均超过了对比算法。此外,适应度标准偏差的比较实验也证实了BIAFS算法的高稳定性,表明其在多个数据集上能更加稳健地寻找最优解。上述实验结果证明了BIAFS算法在特征选择任务中的有效性和优越性。

数字化治理下多主体食品安全动态策略分析

在食品安全治理方式向数字化治理转变的背景下,建立随机微分博弈模型,分析无政府补贴的分散式决策、有政府补贴的分散式决策以及集中式决策三种模式下政府部门与食品经营企业的食品安全数字监管策略及收益问题,并结合贝因美公司的典型案例进行数值分析。研究表明:分散式决策下,当政府部门对企业的食品安全数字化监管提供补贴时,可以实现系统的帕累托改善;集中式决策下,政府部门和食品经营企业的系统收益能够实现三种情形中的帕累托最优,并且食品安全水平的期望值最高,波动最显著。