高密度中心城区蓝绿空间冷岛效应及其影响因素——以北京五环路以内地区为例

蓝绿空间作为城市绿色基础设施的重要组成部分，对促进城市热环境健康、改善局地微气候具有重要作用。利用Landsat 8遥感影像、土地利用等数据，基于辐射传输方程算法、K均值聚类算法、相关性分析等方法，量化了典型的高密度中心城区--北京五环快速路以内地区的1199块1hm²以上的蓝绿空间冷岛效应的表征指标，并分析与蓝绿空间规模、形状复杂度、景观组成、环境组成、植被覆盖等要素的相关关系，还根据蓝绿空间的不同降温特性进行分类，探讨每类蓝绿空间在缓解高密度中心城区热岛效应中的独特作用、优势与机制。结果表明：（1）蓝绿空间的规模、形状复杂度、景观组成等景观要素与冷岛效应的关系显著，如总面积、绿地面积和水体面积与降温幅度、降温范围、降温服务呈显著正相关，与降温效率和降温速率呈显著负相关；周长与降温范围、降温服务呈显著正相关，与降温效率和速率呈显著负相关；周长面积比与降温幅度和降温服务呈显著负相关，与降温效率和蓝绿空间自身温度呈显著正相关，而形状指数则与降温范围和降温服务呈显著正相关。（2）蓝绿空间的环境要素与冷岛效应也存在相关关系。蓝绿空间之间会产生冷岛效应的协同与促进现象，蓝绿空间降温范围内的其他蓝绿空间的总面积与该蓝绿空间的降温幅度、降温范围、降温服务和辐射距离呈显著正相关，与蓝绿空间自身温度呈显著负相关。（3）蓝绿空间的总面积、水体面积、周长与降温幅度之间，周长面积比与降温效率之间存在阈值，为节约土地资源、保证降温效果，建议不应过多超过阈值。（4）基于蓝绿空间在降温幅度、效率、辐射距离等方面的差异，将蓝绿空间划分为4类。高密度中心城区蓝绿空间规划建设应充分评估区域降温需求，了解蓝绿空间降温现状，合理配置具有不同降温特性和优势的蓝绿空间，在土地和资金有限的情况下，充分发挥各类蓝绿空间的冷岛效应。本研究有助于政府和规划师摸清当前蓝绿空间冷岛效应的现状、问题和发展潜力，对理论和实践具有一定参考意义。     

Synthesis and structure–activity relationships of PI3K/mTOR dual inhibitors from a series of 2-amino-4-methylpyrido[2,3-d]pyrimidine derivatives

Inhibition of the phosphoinositide 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) signaling pathway by PI3K/mTOR dual inhibitors provides a promising new approach to the treatment of cancers. In this Letter, we identified structurally novel and potent PI3K/mTOR dual inhibitors from a series of 2-amino-4-methylpyrido[2,3-d]pyrimidine derivatives. Their synthesis and structure–activity relationships are reported.     

Association of single nucleotide polymorphisms in the microRNA miR‐1596 locus with residual feed intake in chickens

MicroRNAs are an abundant class of small non‐coding RNAs that regulate gene expression. Genetic variations in microRNA sequences may be associated with phenotype differences by influencing the expression of microRNAs and/or their targets. This study identified two single nucleotide polymorphisms (SNPs) in the genomic region of the microRNA miR‐1596 locus of chicken. Of the two SNPs, one was 95 bp upstream of miR‐1596 (g.5678784A>T) and the other was in the middle of the sequence producing the mature microRNA gga‐miR‐1596‐3p (g.5678944A>G). Genotypic distribution of the two SNPs had large differences among 12 chicken breeds (lines), especially between the fast‐growing commercial lines and the slow‐growing Chinese indigenous breeds for the g.5678784A>T SNP. Only the g.5678784A>T SNP was significantly associated with residual feed intake (RFI) in the F₂ population derived from a fast‐growing and a slow‐growing broiler as well as in the pure Huiyang bearded chicken. The birds with the AA genotype of the g.5678784A>T SNP had lower RFI and higher expression of the mature gga‐miR‐1596‐3p microRNA of miR‐1596 than did those with the other genotypes of the same SNP. We also found that the expression of the mature gga‐miR‐1596‐3p microRNA of miR‐1596 was significantly associated with RFI. These findings suggest that miR‐1596 can become a candidate gene related to RFI, and its genetic variation may contribute to changes in RFI by altering expression levels of the mature gga‐miR‐1596‐3p microRNA in chicken.     

Delayed egg production and a possible group effect in the blowfly Calliphora vicina

Abstract .Protein-fed Calliphora vicina , F₁ offspring of wild flies in two cages with lower and higher fly densities showed variable delay in starting oocyte vitellogenesis at ambient semi-natural temperatures in warm July–August weather in 1996 and 1997 at Durham in northern England (54°45' N). The high-density flies in 1996 showed no delay, in that the thermal sum (degree-days) experienced was 133, comparable to 18°C constant, assuming the lower threshold for egg maturation to be 5°C. Low-density cages and flies in a large outdoor cage (2 m³) in both years showed delays in production of first eggs of 34 days (thermal sum 293 degree-days) in 1996 and 32 days (396 degree-days) in 1997, and longer delays for other individuals. Delays in egg production at low densities relative to high densities seem to be a group effect of unknown mechanism.     

Novel tracking function of moving target using chaotic dynamics in a recurrent neural network model

Chaotic dynamics introduced in a recurrent neural network model is applied to controlling an object to track a moving target in two-dimensional space, which is set as an ill-posed problem. The motion increments of the object are determined by a group of motion functions calculated in real time with firing states of the neurons in the network. Several cyclic memory attractors that correspond to several simple motions of the object in two-dimensional space are embedded. Chaotic dynamics introduced in the network causes corresponding complex motions of the object in two-dimensional space. Adaptively real-time switching of control parameter results in constrained chaos (chaotic itinerancy) in the state space of the network and enables the object to track a moving target along a certain trajectory successfully. The performance of tracking is evaluated by calculating the success rate over 100 trials with respect to nine kinds of trajectories along which the target moves respectively. Computer experiments show that chaotic dynamics is useful to track a moving target. To understand the relations between these cases and chaotic dynamics, dynamical structure of chaotic dynamics is investigated from dynamical viewpoint.     

Genome‐enabled development of DNA markers for ecology,evolution and conservation

Molecular markers have become a fundamental piece of modern biology’s toolkit. In the last decade, new genomic resources from model organisms and advances in DNA sequencing technology have altered the way that these tools are developed, alleviating the marker limitation that researchers previously faced and opening new areas of research for studies of non‐model organisms. This availability of markers is directly responsible for advances in several areas of research, including fine‐scaled estimation of population structure and demography, the inference of species phylogenies, and the examination of detailed selective pressures in non‐model organisms. This review summarizes methods for the development of large numbers of DNA markers in non‐model organisms, the challenges encountered when utilizing different methods, and new research applications resulting from these advances.     

川西盆周丘陵地区油菜作物生态效应的初步探讨

名山县位于东经103°08′,北纬30°06′,是四川省商品粮油基地县之一,属川西盆周丘陵地区。年平均气温15.5℃,日照1052.0小时,降雨量1519.9mm,一年两熟,能满足油菜全生育期的需要。全县油菜发展较快,1989年较1983年种植面积扩大了33.91%,达到6000ha;总产增加30.35%,达到5958.1t。     

NEW LIGHT ON THE SCALING OF METABOLIC RATE WITH THE SIZE OF ALGAE

The scaling of metabolic rate with the size of algae has been discussed and researched at length. The observation that algae usually have exponents b in the equation R = a· W ^{− b} (where R is the specific growth rate, W is the organism [cell] biomass, and a and b are constants) equal to or higher than the value of −0.25 for many other organisms is generally related to resource-saturated (maximal) values of R. Recent work has shown that the exponent b for light-limited growth is more negative than −0.25. This was predicted from considerations of the package effect in photon absorption, as modulated by the volume-specific pigment content of the cells, and the photosynthetic unit size. Further work is needed to extrapolate these findings to fluctuating light environments. This minireview puts the recent work into a broader context and suggests how further work could quantify the roles of optical thickness and of spatial and temporal variations in the radiation field in determining metabolic rates.     

Air pollution and gene-specific methylation in the Normative Aging Study

The mechanisms by which air pollution has multiple systemic effects in humans are not fully elucidated, but appear to include inflammation and thrombosis. This study examines whether concentrations of ozone and components of fine particle mass are associated with changes in methylation on tissue factor (F3), interferon gamma (IFN-γ), interleukin 6 (IL-6), toll-like receptor 2 (TLR-2), and intercellular adhesion molecule 1 (ICAM-1). We investigated associations between air pollution exposure and gene-specific methylation in 777 elderly men participating in the Normative Aging Study (1999–2009). We repeatedly measured methylation at multiple CpG sites within each gene’s promoter region and calculated the mean of the position-specific measurements. We examined intermediate-term associations between primary and secondary air pollutants and mean methylation and methylation at each position with distributed-lag models. Increase in air pollutants concentrations was significantly associated with F3, ICAM-1, and TLR-2 hypomethylation, and IFN-γ and IL-6 hypermethylation. An interquartile range increase in black carbon concentration averaged over the four weeks prior to assessment was associated with a 12% reduction in F3 methylation (95% CI: -17% to -6%). For some genes, the change in methylation was observed only at specific locations within the promoter region. DNA methylation may reflect biological impact of air pollution. We found some significant mediated effects of black carbon on fibrinogen through a decrease in F3 methylation, and of sulfate and ozone on ICAM-1 protein through a decrease in ICAM-1 methylation.