Effect of epidermal growth factor on follicle-stimulating hormone-induced proliferation of granulosa cells from chicken prehierarchical follicles

The development of ovarian follicular cells is controlled by multiple circulating and local hormones and factors, including follicle-stimulating hormone (FSH) and epidermal growth factor (EGF). In this study, the stage-specific effect of EGF on FSH-induced proliferation of granulosa cells was evaluated in the ovarian follicles of egg-laying chickens. Results showed that EGF and its receptor (EGFR) mRNAs displayed a high expression in granulosa cells from the prehierarchical follicles, including the large white follicle (LWF) and small yellow follicle (SYF), and thereafter the expression decreased markedly to the stage of the largest preovulatory follicle. SYF represents a turning point of EGF/EGFR mRNA expression during follicle selection. Subsequently the granulosa cells from SYF were cultured to reveal the mediation of EGF in FSH action. Cell proliferation was remarkably increased by treatment with either EGF or FSH (0.1–100 ng/ml). This result was confirmed by elevated proliferating cell nuclear antigen (PCNA) expression and decreased cell apoptosis. Furthermore, EGF-induced cell proliferation was accompanied by increased mRNA expressions of EGFR, FSH receptor, and the cell cycle-regulating genes (cyclins D1 and E1, cyclin-dependent kinases 2 and 6) as well as decreased expression of luteinizing hormone receptor mRNA. However, the EGF or FSH-elicited effect was reversed by simultaneous treatment with an EGFR inhibitor AG1478. In conclusion, EGF and EGFR expressions manifested stage-specific changes during follicular development and EGF mediated FSH-induced cell proliferation and retarded cell differentiation in the prehierarchical follicles. These expressions thus stimulated follicular growth before selection in the egg-laying chicken.     

应用型本科院校植物学野外实习教学改革初探

植物学野外实习是应用型本科院校生物教学过程中必不可少的实践环节,结合野外实习经验,探索植物学野外实习模式的改革。强调在巩固和加强基础知识学习的同时,倡导野外实习与科研活动相结合,从而提高学生的基本技能和创新能力的培养。     

新世纪自学考试存在的主要问题及其补正

当前,自考存在着教育功利主义及应试教育倾向,存在着专业课程设置僵化、考试评价方式和自学媒体单一等弊端。新世纪,必须进一步改革和完善自考制度,明确教育培养目标,克服自考的应试教育倾向,改革考试内容,建立多元化评价体系,实行开放的课程设置体系,加强对自学媒体的建设,以促进考生综合素质的提升和全面发展。     

焦虑情绪和适应能力对大学新生学习生活的影响

采用焦虑自评量表和心理适应性自测量表对67名大学新生进行三次心理健康状况调查,结果显示有一般心理问题的学生占28.36%;有严重心理问题的学生占6.00%。焦虑产生的原因有生理需要不满足、安全感缺失、没有归属感、实现自我价值有压力。高校可以通过素质教育,加强校园文化建设,提高学生的适应能力,完善心理健康教育系统,缓解大学生的心理焦虑。     

浅议高校大学生群体性突发事件的预防管理

因社会因素、学校教育管理因素、学生自身因素等原因,高校大学生群体性突发事件时有发生,严重影响了高校的安全稳定。高校应增强危机意识,建立大学生群体性突发事件的识别、研判等机制,加强教育,提高管理水平,建立通畅的学生群体利益表达渠道,努力构建和谐校园文化,有效预防大学生群体性突发事件的发生。     

光纤通信系统中二阶偏振模色散补偿理论研究

随着光通信技术不断的发展和系统传输容量的不断增长,偏振模色散在光纤通信系统中已经成为严重影响系统性能的主要因素之一,也成为目前光通信领域研究的热点问题之一.因此,本文首先分析了一阶偏振模色散补偿理论,在此基础上进一步研究了二阶偏振模色散的理论补偿方法.     

Lumped parameter model for resonant frequency estimation of a thermoacoustic engine with gas-liquid coupling oscillation

Gas-liquid coupling oscillation is a novel approach to reducing the resonant frequency and to elevating the pressure amplitude of a thermoacoustic engine. If a thermoacoustic engine is used to drive low-frequency pulse tube refrigerators, the frequency matching between the thermoacoustic engine and the refrigerator plays an important role. Based on an acoustic-electric analogy, a lumped parameter model is proposed to estimate the resonant frequency of a standing-wave thermoacoustic engine with gas-liquid coupling oscillation. Furthermore, a simplified lumped parameter model is also developed to reduce the computation complexity. The resonant frequency dependence on the mean pressure, the gas space volume, and the water column length is computed and analyzed. The impact of different working gases on the resonant frequency is also discussed. The effectiveness of the models is validated by comparing the computed results with the experimental data of the gas-liquid coupling oscillation system. An increase in the mean working pressure can lead to a rise in the resonant frequency, and a lower resonant frequency can be achieved by elongating the liquid column. In comparison with nitrogen and argon, carbon dioxide can realize a lower frequency due to a smaller specific heat ratio.     

微观经济学理解力的中日差异研究——基于TUCE-4测试结果的量化分析

本文通过调查中国和日本大学生微观经济学的理解力现状,分析了中日两国大学生的微观经济学理解力的差异与其样本特征的关系,进一步从微观经济学内涵角度分析了中日大学生的差异,并对中国的经济学教育提出了改进的建议.     

Buckling response of offshore pipelines under combined tension, bending, and external pressure

The buckle and collapse of offshore pipeline subjected to combined actions of tension, bending, and external pressure during deepwater installation has drawn a great deal of attention. Extended from the model initially proposed by Kyriakides and his co-workers, a 2D theoretical model which can successfully account for the case of simultaneous tension, bending, and external pressure is further developed. To confirm the accuracy of this theoretical method, numerical simulations are conducted using a 3D finite element model within the framework of ABAQUS. Excellent agreement between the results validates the effectiveness of this theoretical method. The model is then used to study the effects of several important factors such as load path, material properties, and diameter-to-thickness ratio, etc., on buckling behaviors of the pipes. Based upon parametric studies, a few significant conclusions are drawn, which aims to provide the design guidelines for deepwater pipeline with solid theoretical basis.     

Investigating the Development of the “Mobile Museum” from the Perspective of Service

During economic development, modern museums face competition from various leisure activities and entertainment sites, and to achieve sustainable development, museums should reflect on providing high‐quality service to satisfy visitors’ expectations. Based on service design‐related theories, this research team conducted a case study to explore the planning, implementation, and meaning of Mobile Museums. It investigated design development from the perspective of public service design and summarized the policy, design, and service satisfaction results for Mobile Museums. Finally, the similarities in service processes are discussed between Mobile Museums and the general service industry. According to this study, attracting more visitors is the biggest issue facing museums today, as are the ways in which museums must actively provide service and become recognized to compete with others. This study identifies the onstage and backstage support of museums as well as their cultural features and non‐profit services.