A potato model intercomparison across varying climates and productivity levels

A potato crop multimodel assessment was conducted to quantify variation among models and evaluate responses to climate change. Nine modeling groups simulated agronomic and climatic responses at low‐input (Chinoli, Bolivia and Gisozi, Burundi)‐ and high‐input (Jyndevad, Denmark and Washington, United States) management sites. Two calibration stages were explored, partial (P1), where experimental dry matter data were not provided, and full (P2). The median model ensemble response outperformed any single model in terms of replicating observed yield across all locations. Uncertainty in simulated yield decreased from 38% to 20% between P1 and P2. Model uncertainty increased with interannual variability, and predictions for all agronomic variables were significantly different from one model to another (P < 0.001). Uncertainty averaged 15% higher for low‐ vs. high‐input sites, with larger differences observed for evapotranspiration (ET), nitrogen uptake, and water use efficiency as compared to dry matter. A minimum of five partial, or three full, calibrated models was required for an ensemble approach to keep variability below that of common field variation. Model variation was not influenced by change in carbon dioxide (C), but increased as much as 41% and 23% for yield and ET, respectively, as temperature (T) or rainfall (W) moved away from historical levels. Increases in T accounted for the highest amount of uncertainty, suggesting that methods and parameters for T sensitivity represent a considerable unknown among models. Using median model ensemble values, yield increased on average 6% per 100‐ppm C, declined 4.6% per °C, and declined 2% for every 10% decrease in rainfall (for nonirrigated sites). Differences in predictions due to model representation of light utilization were significant (P < 0.01). These are the first reported results quantifying uncertainty for tuber/root crops and suggest modeling assessments of climate change impact on potato may be improved using an ensemble approach.     

Variation in thermal niche of a declining river‐breeding frog: From counter‐gradient responses to population distribution patterns

相似文献   

天山中西段不同地区雪岭云杉径向生长对气候变暖的响应差异

为研究乌苏和石河子地区雪岭云杉（Picea schrenkiana）径向生长对气候变暖的响应差异状况,利用响应函数及滑动相关分析等树轮气候学方法,研究了2个地区森林下限雪岭云杉径向生长与气候因子的响应关系。结果表明：乌苏和石河子地区雪岭云杉生长均与生长季的气候因子呈显著相关关系。但乌苏和石河子地区雪岭云杉生长对当地气候因子的响应也存在差异,乌苏地区雪岭云杉径向生长与上一年7、9月平均气温呈显著负相关,与当年8月降水、上一年9月及当年8月平均相对湿度和上一年7~10月的scPDSI呈显著正相关。石河子地区雪岭云杉径向生长与当年1月平均湿度和当年1、2月的scPDSI呈显著正相关。此外,乌苏地区树轮宽度指数具有与温度升高而下降的“分离现象”,而石河子地区树轮宽度指数具有与温度升高相一致的趋势。升温导致的水分胁迫是造成乌苏地区雪岭云杉径向生长与温度变化趋势相反的重要因素。生长季的温度和降水的增加对石河子地区雪岭云杉径向生长有促进作用。乌苏地区雪岭云杉径向生长对5~7月平均气温和降水量变化敏感性上升;石河子地区雪岭云杉径向生长对5~7月降水量变化敏感性上升,而对5~7月平均气温变化敏感性下降。结果显示,气候变化的区域差异是造成乌苏和石河子地区雪岭云杉径向生长趋势不同以及各年表序列对温度和降水变化敏感性变化的主要气候因素。     

Modelling the spatiotemporal dynamics of chemovirotherapy cancer treatment

Chemovirotherapy is a combination therapy with chemotherapy and oncolytic viruses. It is gaining more interest and attracting more attention in the clinical setting due to its effective therapy and potential synergistic interactions against cancer. In this paper, we develop and analyse a mathematical model in the form of parabolic non-linear partial differential equations to investigate the spatiotemporal dynamics of tumour cells under chemovirotherapy treatment. The proposed model consists of uninfected and infected tumour cells, a free virus, and a chemotherapeutic drug. The analysis of the model is carried out for both the temporal and spatiotemporal cases. Travelling wave solutions to the spatiotemporal model are used to determine the minimum wave speed of tumour invasion. A sensitivity analysis is performed on the model parameters to establish the key parameters that promote cancer remission during chemovirotherapy treatment. Model analysis of the temporal model suggests that virus burst size and virus infection rate determine the success of the virotherapy treatment, whereas travelling wave solutions to the spatiotemporal model show that tumour diffusivity and growth rate are critical during chemovirotherapy. Simulation results reveal that chemovirotherapy is more effective and a good alternative to either chemotherapy or virotherapy, which is in agreement with the recent experimental studies.     

Lumbar spine finite element model for healthy subjects: development and validation

Finite element (FE) method is a proven powerful and efficient tool to study the biomechanics of the human lumbar spine. However, due to the large inter-subject variability of geometries and material properties in human lumbar spines, concerns existed on the accuracy and predictive power of one single deterministic FE model with one set of spinal geometry and material properties. It was confirmed that the combined predictions (median or mean value) of several distinct FE models can be used as an improved prediction of behavior of human lumbar spine under identical loading and boundary conditions. In light of this improved prediction, five FE models (L1-L5 spinal levels) of the human lumbar spine were developed based on five healthy living subjects with identical modeling method. The five models were extensively validated through experimental and computational results in the literature. Mesh convergence and material sensitivity analysis were also conducted. We have shown that the results from the five FE models developed in this paper were consistent with the experimental data and simulation results from the existing literature. The validated modeling method introduced in this study can be used in modeling dysfunctional lumber spines such as disc degeneration and scoliosis in future work.     

毛乌素沙地参考作物蒸散量变化特征与成因分析

根据毛乌素沙地典型站点近60年(1955—2014年)逐日气象数据,利用Penman-Monteith公式计算毛乌素沙地各气象站点参考作物蒸散量(reference crop evapotranspiration,ET_0)及研究区域内整体ET_0。Mann-Kendall趋势检验法和Arc GIS的协同克里格插值法用于分析ET_0时空变化特征,同时,利用敏感性分析方法对ET_0的变化成因进行分析。结果表明:(1)近60年毛乌素沙地ET_0多年平均值为1048.81mm,年际变化呈现缓慢上升趋势。年内变化夏季最高,冬季最低。区域内ET_0空间分布整体呈现自西向东递减趋势。(2)ET_0年变化对风速的敏感程度最大,日照时数和气温次之,相对湿度最小。春、秋两季ET_0变化对日照时数最为敏感;夏、冬两季ET_0变化对相对湿度最为敏感。空间分布上,毛乌素沙地东南部地区为气温敏感系数高值区,西北部地区为相对湿度和日照时数敏感系数高值区,南部为风速敏感系数高值区。(3)通过计算气象因子对ET_0变化的贡献量得出,气温是影响毛乌素沙地ET_0年变化的主导因子。夏季ET_0变化的主导因子是风速;春、秋、冬三季主导因子是气温。空间分布上,毛乌素沙地西南部地区ET_0变化的主导因子为风速,东部地区主导因子为气温。     

基于生态重要性和敏感性的西南山地生态安全格局构建——以云南省大理白族自治州为例

生态安全格局构建是快速城市扩张背景下缓解生态保护和土地开发矛盾、保证区域生态安全的有效途径。源地和阻力面是生态安全格局构建的重要基础,当前阻力面构建多关注生态要素而忽视与区域典型生态问题相对应的生态过程表征。以西南山地地区--云南省大理白族自治州为研究区,选取生物资源保护、水资源安全和营养物质保持等生态系统服务评估生态重要性从而识别源地,基于地质灾害、土壤侵蚀、石漠化等生态敏感性构建生态阻力面,并运用最小累积阻力模型识别组团廊道和景观廊道,从而构建山地生态安全格局。研究表明,大理州生态安全源地总面积14416.64 km~2,占全州土地总面积的50.93%;关键生态廊道分为组团廊道和景观廊道两类,分别长404.7 km和208.4 km,以"一轴三带"形式呈树状辐射分布。生态安全格局中的生态源地和廊道应成为低丘缓坡土地资源开发中的禁止开发区。生态重要性源地识别和生态敏感性阻力面分析方法可为生态安全格局构建提供新思路,研究结果对于大理州山地城镇建设的用地选择和空间扩张提供定量指引。     

Impairment of insulin signalling in peripheral tissue fails to extend murine lifespan

Impaired insulin/IGF1 signalling has been shown to extend lifespan in model organisms ranging from yeast to mammals. Here we sought to determine the effect of targeted disruption of the insulin receptor (IR) in non‐neuronal tissues of adult mice on the lifespan. We induced hemizygous (PerIRKO^+/?) or homozygous (PerIRKO^?/?) disruption of the IR in peripheral tissue of 15‐weeks‐old mice using a tamoxifen‐inducible Cre transgenic mouse with only peripheral tissue expression, and subsequently monitored glucose metabolism, insulin signalling and spontaneous death rates over 4 years. Complete peripheral IR disruption resulted in a diabetic phenotype with increased blood glucose and plasma insulin levels in young mice. Although blood glucose levels returned to normal, and fat mass was reduced in aged PerIRKO^?/? mice, their lifespan was reduced. By contrast, heterozygous disruption had no effect on lifespan. This was despite young male PerIRKO^+/? mice showing reduced fat mass and mild increase in hepatic insulin sensitivity. In conflict with findings in metazoans like Caenorhabditis elegans and Drosophila melanogaster, our results suggest that heterozygous impairment of the insulin signalling limited to peripheral tissues of adult mice fails to extend lifespan despite increased systemic insulin sensitivity, while homozygous impairment shortens lifespan.     

中国生态环境脆弱区范围界定

中国生态环境脆弱区既是生态退化区域, 也是贫困人口集中分布区, 但其空间分布范围至今仍然不明确。本研究针对土地沙化、水土流失和石漠化等典型生态问题, 采用遥感和GIS技术, 建立评价指标体系及评价模型, 综合评价了全国生态环境敏感性, 定量揭示敏感性空间分布特征。在此基础上, 结合政府文件和已有的研究成果, 识别出全国生态脆弱区分布范围。结果显示, 生态极敏感区主要分布在我国西北干旱/半干旱地区、西南湿润地区、东南湿润地区以及黄土高原丘陵沟壑区; 高度敏感区主要分布在阿尔泰山、天山、阴山南麓、科尔沁沙地、呼伦贝尔沙地、羌塘高原西部、横断山和东南丘陵山地等区域。在全国划定了18个重点生态脆弱区, 总面积240.1万km², 并明确了每个脆弱区的名称、类型、面积、分布范围以及面临的主要生态问题。完成的中国生态脆弱区分布图为全国生态保护红线划定提供了参考底图。     

水稻雄性不育恢复系明恢63的感光基因分析

水稻恢复系明恢63是中国应用面积最大、利用最广泛的恢复系。利用抽穗期感光性近等基因系EG0～EG7及ER～LR对明恢63进行的分析表明,明恢63在E1、E2、E3位点分别带有E1、e3、E3基因,在Se-1位点带无感光功能的Se-1^e基因。进一步用抽穗期QTL近等基因系NIL(Hd1)和NIL（Hd4)进行的研究表明,明恢63带有显性感光基因E1和无感光功能的Se-1^e基因,并推测明恢63带有能抑制E,基因表达的隐性抑制基因。认为籼型杂交稻抽穗期受不育系和恢复系感光基因及感光性抑制基因的共同作用。初步讨论了明恢63广适性的遗传基础。