[Cumulative effects of K-function in the research of point patterns]. / ç‚¹æ ¼å±€ç ”ç©¶è¿‡ç¨‹ä¸­K-函数的累积效应.

The spatial pattern of plant population is one of primary issues in ecological research. Point pattern analy-sis is considered as an important method to study the spatial pattern of plant population. Ripley's K function has been commonly used for point pattern analysis. However, the cumulative effect of Ripley's K function may lead to specific spatial pattern charcteristics. To explore how the cumulative effect of Ripley's K function affects population pattern, the data of clumped distribution, random distribution and regular distribution of Stipa grandis were simulated by R software. All data generated by R software were analyzed by Ripley's K function and the non-cumulative pairwise correlation function g(r). The results showed that for clumped distribution (or regular distribution), the cumulative effect of Ripley's K function was manifested in two aspects. On the one hand, the scale of clumped distribution (or regular distribution) was increased due to Ripley's K function. On the other hand, Ripley's K function could detect the difference of the distribution of cluster (or negative interaction range) in the sampling space, exhibiting different pattern characteristics. For random distribution, Ripley's K function had no cumulative effect. In conclusion, the combination of Ripley's K function and pairwise correlation function by collecting replicate samples could better reveal the essential characteristics of the pattern in the study of population pattern.

[Agricultural climate regionalization of dryland farming for potato in Yinshan based on GIS].

Based on the meteorology dataset of 34 stations over the Yinshan area through the recent 30 years (1982-2010), we investigated the key environmental variables influencing potato yield using the correlation and regression methods. Two environmental variables, including the mean temperature difference, precipitation during the growing season, were selected as the major indexes for determining the suitable area for planting potato. Using the GIS-based small grid calculation model, we interpolated these two major environmental variables and produced the climatic map for potato in Yinshan area. The results showed the high potato yield area located in Qianshan and southern Houshan, and the medium-yield division was mainly concentrated in the central Houshan and north-west Qianshan, the low-yield division was distributed mainly in northern Yinshan. Moreover, this study examined the spatial patterns of potato production, and evaluated the stability of potato yield by combining the relative variability of potato yield. This study could provide valuable references for planting potato in Yinshan area.

[Correlation between pneumonia and meteorological factors in children from Hohhot].

OBJECTIVE: To study the correlation between the morbidity of pneumonia and meteorological factors in children from Huhhot, in order to provide a basis to prevent and decrease the morbidity of childhood pneumonia. METHODS: A total of 5087 hospitalized children with pneumonia from Huhhot between January 2004 and December 2009 were enrolled. The Circular Distribution method was applied to analyze the seasonal characteristics of the morbidity of pneumonia. The Linear Stepwise Regression Analysis was applied to investigate the relationship between the morbidity of childhood pneumonia and meteorological factors. RESULTS: The morbidity of childhood pneumonia displayed an obvious seasonal trend. Childhood pneumonia was common in winter and spring and its peak morbidity was noted in March. The higher morbidity of pneumonia was related to low air temperature, high air pressure, low precipitation, low humidity and high wind velocity. CONCLUSIONS: Meteorological factors affect the morbidity of childhood pneumonia in Hohhot, and should be considered in the prevention of the disease.