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1.
榕母管蓟马Gynaikothrips ficorum (Marchal)是一种已扩散至各大洲的榕树主要害虫, 目前在云南省热带及亚热带区域发生危害亦较为严重。为了揭示榕母管蓟马在云南省不同地理种群间的遗传变异, 测定了10个地理种群145个个体的mtDNA COⅠ基因的646 bp序列, 对地理种群间的序列变异和遗传分化进行了分析。结果表明: 10个地理种群间的COⅠ基因共有38个变异位点和6个单倍型, 其中1个单倍型为8个种群所共享。种群间的遗传距离范围为0~0.043, 其中瑞丽、 芒市、 玉溪、 呈贡种群间的遗传距离最小, 宜良和陇川、 墨江种群间的遗传距离最大, 种群遗传距离大小与其相对地理距离的远近之间没有相关性。分子方差分析显示3组(组1: 陇川、 瑞丽、 芒市、 玉溪、 呈贡、 墨江、 临沧、 勐腊8个种群; 组2: 蒙自种群; 组3: 宜良种群)之间已经具有明显的遗传分化, Fst值为0.9828(P<0.05), Nm值为0.01, 但是仅0.0172的遗传变异来自组内。采用邻接法(NJ)构建分子系统树, 单倍型被分成3组与各自的地理区域相对应的簇群, 各组之间未发现共享的单倍型。分子系统树显示3组的聚类结果与地理分布格局并不对应。综合采集地寄主植物的状况, 初步推测蒙自和宜良种群出现的遗传分化可能是由于寄主植物生长状况及品种不同引起的。各地理种群中的单倍型在网络中介图上散布在不同的分布群中, 缺乏明显的地理分布格局。  相似文献   

2.
梁保平  雷艳  覃业努  梁丽敏 《生态学报》2018,38(12):4526-4536
随着城市化的快速发展与城市规模日益扩张,城市景观空间结构不断地被人为改变着,不合理的景观空间格局既削弱了区域的经济和社会发展功能,影响着城市生态环境质量的不断提高,也进一步制约着城市的可持续发展进程。以广西3座典型中心城市——南宁、柳州和桂林市为研究对象,利用6景Landsat5 TM和Landsat8 OLI/TIRS影像数据,通过遥感影像分类技术提取研究区的土地利用景观信息,对典型城市1990—2015年的景观空间格局特征与生态过程进行对比分析,旨在揭示快速城市化阶段重点城市核心景观要素的时空演化规律。结果表明:(1)在城市化进程加快的背景下,广西各典型城市的景观空间格局均发生了剧烈的变化。受人为影响强烈的土地利用景观类型变动最为显著,建设用地景观的不断扩张与耕地、林地景观的缩减是城市化发展的基本特征。(2)在水平空间上,城市建筑景观逐渐由核心圈层向外围圈层扩展,外围区的自然景观受人工干扰强度加大,景观类型逐渐丰富,但破碎化程度加剧。(3)在垂直空间上,城市景观类型呈现较显著的海拔分异特征,中、低海拔区是城镇化最集中的地带,建设用地的景观优势度增长最为显著。高海拔区因但受城市扩张与农业开发活动的胁迫,自然景观的优势度与团聚性呈下降趋势。(4)从城市功能定位来看,南宁、柳州和桂林市作为广西3座不同功能类型的中心城市,它们在区域社会经济发展方面起到重要的辐射和引领作用。该研究为科学开展城市景观规划、实施城市生态环境管理和推进广西城市化健康有序发展提供参考依据。  相似文献   

3.
Del Istmo大学的新校园坐落于危地马拉市边迅速发展的圣伊莎贝尔社区。这个49公顷的基地掩映在美丽的山坡与山谷中。大学希望扩招至6200名学生,计划在20年内分期实现。大学教学宗旨与目标包括对个人以及周边社区的高度关注。新校园的空间形式是大学对社会目标的回应,与推进现代学习关系的体现。考虑到影响基地的生态力与系统,新建筑充分考虑位置与朝向,促进自然通风与光线引入。校园是可持续策略的典范。  相似文献   

4.
In this study, we estimate the effect of fast food environment surrounding schools on childhood body mass index (BMI). We use two methods that arrive at a similar conclusion, but with different implications. Using school distance from the nearest federal highway to instrument for restaurant location, we find the surrounding restaurants to only marginally affect a student’s BMI measure. The effect size also decreases with increasing radial distances from school, 0.016 standard deviations at one-third of a mile and 0.0032 standard deviations at a mile radial distance. This indicates the decreasing influence of restaurants on a child’s BMI as its distance from school increases. On a subset of students who were exogenously assigned to different school food environment, we find no effect of the fast food restaurants. An important contextual aspect is that nearly all schools in this sample observed closed campus policy, which does not allow students to leave campus during lunch hours.  相似文献   

5.
Scientific evidence associates indoor environment pollutants with respiratory effects (asthma and allergies), and children constitute one of most sensitive groups. Indoor air quality (IAQ) in schools may indeed be a significant health factor for children, with effects on school attendance and performance. Our aim was to characterize IAQ of classrooms in Maia County (north of Portugal) for which there was no information available. The study was conducted in 21 of the 40 primary schools, selected by stratified random sampling. Depending on the dimension, one or two classrooms were tested at each school. Walkthrough surveys of school grounds, buildings, and individual classrooms were done. Continuous measurements were taken of temperature, relative humidity, airborne respirable particles, total volatile organic compounds, and carbon dioxide, whereas bioaerosols were counted on Plate Count Agar during regular school activities. The indoor arithmetic mean for PM10, CO2, TCOV, and bioaerosol concentrations were 0.14 mg/m3, 999 ppm, 0.41 mg/m3, and 4140 UCF/m3, respectively. The values of PM10 and CO2 were close to their acceptable maximum values, but bioaerosols were much higher. This study supports previous studies conducted in school environments and emphasizes the need for proactive indoor air quality audits in school buildings.  相似文献   

6.
建筑和庭院的关系一直以来是建筑学重要的研究课题之一。以清华大学八家附小建筑与庭院设计为例进行研究,提出建筑与庭院“共舞”的理念,总结了形成庭院格局的3种设计模式和庭院的3种设计模式。试图创造建筑和庭院“共舞”的校园环境,探寻其连续而整体的、丰富而多层次的美,是本设计与研究的努力目标。  相似文献   

7.
The aim of this study was to investigate experimentation with smoking among primary school students in China. Data were acquired from a recent survey of 4,073 students in grades 4 to 6 (ages 9–12) in 11 primary schools of Ningbo City. The questions were adapted from the Global Youth Tobacco Survey (GYTS). Results suggest that although the Chinese Ministry of Education (MOE) encourages smoke-free schools, experimentation with cigarettes remains a serious problem among primary school students in China. Peers, family members, and the school environment play important roles in influencing smoking experimentation among students. Having a friend who smoked, seeing a family member smoke, and observing a teacher smoking on campus predicted a higher risk of experimentation with smoking; the exposure to anti-tobacco materials at school predicted a lower risk of experimentation with smoking. The evidence suggests that public health practitioners and policymakers should seek to ensure the implementation of smoke-free policies and that intervention should target young people, families, and communities to curb the commencement of smoking among children and adolescents in China.  相似文献   

8.
A study was made of the indoor mycobiota in a range of public and private buildings (libraries, museums, laboratories and offices, warehouses, homes and a school) in the city of Havana (Cuba). Culturable airborne fungi were sampled using a slit-to-agar impactor (Chirana aeroscope). High levels of contamination were recorded, with more than 700 colony-forming units per cubic metre of air in 85% of the buildings sampled, and more than 1,000 in 55% of buildings. Of the 28 genera and 31 species identified, the most common were Aspergillus flavus, Aspergillus niger, Penicillium citrinum, Cladosporium cladosporioides and Cladosporium sphaerospermum. Genus and species diversity was analysed, and new findings were obtained regarding Cuba’s atmospheric ecosystem.  相似文献   

9.
Balancing thermal comfort with the requirement of energy conservation presents a challenge in hot and humid areas where air-conditioning (AC) is frequently used in cooling indoor air. A field survey was conducted in Taiwan to demonstrate the adaptive behaviors of occupants in relation to the use of fans and AC in a school building employing mixed-mode ventilation where AC use was managed under a fee-for-service mechanism. The patterns of using windows, fans, and AC as well as the perceptions of students toward the thermal environment were examined. The results of thermal perception evaluation in relation to the indoor thermal conditions were compared to the levels of thermal comfort predicted by the adaptive models described in the American Society of Heating, Refrigerating, and Air-Conditioning Engineers Standard 55 and EN 15251 and to that of a local model for evaluating thermal adaption in naturally ventilated buildings. A thermal comfort-driven adaptive behavior model was established to illustrate the probability of fans/AC use at specific temperature and compared to the temperature threshold approach to illustrate the potential energy saving the fee-for-service mechanism provided. The findings of this study may be applied as a reference for regulating the operation of AC in school buildings of subtropical regions.  相似文献   

10.
Milton Winternitz led Yale Medical School as its Dean from 1920 to 1935. An innovative, even maverick leader, he not only kept the school from going under, but turned it into a first-class research institution. Dedicated to the new scientific medicine established in Germany, he was equally fervent about "social medicine" and the study of humans in their culture and environment. He established the "Yale System" of teaching, with few lectures and fewer exams, and strengthened the full-time faculty system; he also created the graduate-level Yale School of Nursing and the Psychiatry Department, built numerous new buildings, and much more. It is a loss to 21st-century medicine that his dream of an Institute of Human Relations, envisioned as a refuge where social scientists would collaborate with biological scientists in a holistic study of humankind, lasted for only a few years, before falling victim to the more obvious triumphs of medical science and technology. It is sad, too, that he is remembered largely as a Jew presiding over a medical school that, like most others, restricted the number of Jewish students, rather than for his contributions to American medicine.  相似文献   

11.
Undergraduates at elite universities in the US and UK are, according to Dr Warikoo, conflicted about the relation of racial diversity to meritocracy. In the US, white students view racial minorities as academically less qualified but as providing a diversity benefit; UK students view minorities as equal members of a meritocracy but turn a blind eye to racial disparities on and off campus. What Warikoo’s narrative overlooks is the role played by differences between the US and the UK in the educational paths and testing regimes that produce these disparate mentalities. Although 40 per cent of America’s colleges offer test-optional admissions, some like Harvard still require SAT/ACT scores. The SAT/ACT are predictively weak and biased, stigmatizing minorities as underperformers. Test biases and the predictive superiority of high school grades are not widely understood. Warikoo’s proposal to blow up meritocracy with an admissions lottery is to be applauded.  相似文献   

12.
Previous research on black students attending predominantly white colleges has emphasized race-based differences with white students while downplaying differences in social class. This research indicates that class-based differences are an important component of many black students’ discomfort at ‘Northern College’, a school that has traditionally served wealthy white students. Drawing on interviews and participant observation done on campus, I apply cultural capital theory to explain how differences in class-specific cultural styles make campus life difficult for non-affluent blacks and discuss the implications of the findings for future research on black college experiences.  相似文献   

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