基于改进TOPSIS模型的西部河谷型城市生态安全时空分异及障碍因子诊断

西部河谷型城市生态安全及障碍因子诊断对协调西部地区城市生态环境保护与社会经济产业持续发展具有重要意义。基于PSR模型集成改进TOPSIS和障碍度诊断模型,选取2005-2015年西部地区20个典型河谷型城市为评价单元,对生态安全系统时空演化规律及障碍因子进行实证分析。结果表明:1)西部河谷型城市生态安全水平整体呈上升趋势,但总体处于临界安全级(Ⅲ)水平;2)生态安全呈西高东低、北高南低的空间格局特征,生态安全空间差异性明显,但随着时间推移,各城市生态安全差异有缩小趋势,生态安全水平下降的城市数量在减少,生态安全水平上升的城市数量在增加;3)准则层中用地状态和经济响应是制约生态安全的主要障碍因子,指标层中环保投入占财政支出比重、人均公园绿地面积、人均水资源占有量、人均耕地面积、人均城市道路面积、科技投入占财政支出比重、城镇化水平7项因子成为主要的障碍因子。因城市规模不同,西部河谷型城市生态安全主要障碍因子变化特征不一。     

Prenatal diagnosis of trisomy 4p: a new locus for holoprosencephaly?

Trisomy of the short arm of chromosome 4 is a well-known syndrome, and several observations have been made in the last 30 years. Herein, we report a new observation of trisomy 4p in a fetus with a semi-lobar holoprosencephaly (HPE), dysmorphic features and multiple malformations. The diagnosis of HPE was made, at 33 weeks' gestation, on the fetus of a healthy G1P0 woman. Amniocentesis was performed for chromosome analysis and additional material was found on a chromosome 22. The couple elected to terminate the pregnancy and fetal examination was realized. Conventional and molecular cytogenetic studies were performed on the fetus and the parents, which showed that the additional material found on one chromosome 22 corresponded to the short arm of chromosome 4 and therefore led us to establish a diagnosis of trisomy 4p inherited from the malsegregation of a paternal translocation t(4;22)(q12;q11.1). The etiology of HPE is very heterogeneous; it includes non-genetic factors such as maternal diabetes and genetic causes. HPE cases have been described in association with many chromosomal anomalies, trisomy 13 being the most frequent. However, to our knowledge, HPE has never been previously reported in association with a trisomy involving solely the short arm of chromosome 4. Copyright © 2005 John Wiley & Sons, Ltd.