Fractal geometry predicts varying body size scaling relationships for mammal and bird home ranges

Scaling laws that describe complex interactions between organisms and their environment as a function of body size offer exciting potential for synthesis in biology. Home range size, or the area used by individual organisms, is a critical ecological variable that integrates behaviour, physiology and population density and strongly depends on organism size. Here we present a new model of home range-body size scaling based on fractal resource distributions, in which resource encounter rates are a function of body size. The model predicts no universally constant scaling exponent for home range, but defines a possible range of values set by geometric limits to resource density and distribution. The model unifies apparently conflicting earlier results and explains differences in scaling exponents among herbivorous and carnivorous mammals and birds. We apply the model to predict that home range increases with habitat fragmentation, and that the home ranges of larger species should be much more sensitive to habitat fragmentation than those of smaller species.     

热输入对深海X70粗晶区组织和韧性的影响

为解决深海X70管线钢在实际焊接中粗晶区(CGHAZ)的脆化问题,在不同热循环工艺下对X70管线钢进行了热模拟研究。采用Gleeble-3800热模拟机模拟X70管线钢CGHAZ,研究CGHAZ在10～60 kJ/cm不同热输入(HI)条件下组织和韧性的变化规律,并通过光学显微镜(OM)、扫描电镜(SEM)和夏比冲击试验等手段表征CGHAZ的组织和韧性。结果表明,不同热输入下试验钢的组织主要由粒状贝氏体(GB)、贝氏体铁素体(BF)和马-奥组元(M-A组元)组成;当HI不断增大时,BF比例减少,GB比例增加,M-A组元粗化,冲击吸收能先升高再降低;当HI为20 kJ/cm时,BF和GB可获得优异组合,断口为韧性断裂,冲击吸收能达到173.8 J;当HI大于20 kJ/cm时,断口解离断裂,冲击吸收能下降明显,最低为18.8 J。因此,较低的热输入可提高CGHAZ的韧性,使X70管线钢具有高强度、高韧性和良好的焊接性。研究结果可为优化焊接工艺提供理论依据。     

炭基微生物菌剂促进牛粪好氧堆肥腐熟过程研究

为评估炭基微生物菌剂促进牛粪好氧堆肥的腐熟效果,以牛粪为原料加入自制炭基微生物菌剂进行为期34 d的堆肥试验,并以纯牛粪为空白对照,研究堆肥过程中理化指标和微生物群落的变化。结果表明,添加炭基微生物菌剂后,1 d内可使堆温达到53 ℃,堆体最高温度为71.7 ℃,较对照组最高温度高出4.6 ℃,且高温期延长3 d。至堆肥结束时,处理组和对照组的含水率、E₄/E₆,GI分别为29%和33%,1.5和1.9,145.5%和127.6%。通过相关性分析得出,累计温度、含水率、pH值等理化指标相关性数值增大为67%,与细菌门水平间相关性数值增加了56%。添加0.1%(w/w)的炭基微生物菌剂可加快腐熟过程,提高微生物多样性,加快微生物群落的演替和对物料的分解代谢,促进腐熟进程,为炭基微生物菌剂在好氧堆肥中的应用提供了理论依据。     

种植土-碎石绿化带雨水入渗的数值分析

为分析理论解析法求解种植土-碎石绿化带雨水入渗问题的合理性,建立了非饱和种植土-碎石绿化带雨水入渗的有限元模型,模型上边界设置储水表皮,模拟雨水入渗和积蓄,下边界为饱和排水,模型两侧不透水。首先,利用有限元模型模拟了均匀降雨条件下的雨水入渗特征,与理论解析解对比,验证了模型的正确性。然后,利用有限元模型计算石家庄市2年重现期3h设计暴雨雨型条件下种植土的雨水入渗,地表开始积水时间、降雨结束后积水深度、雨量径流系数分别为0.75h,13.6cm和0.24,均匀降雨理论解析解计算结果分别为0.72h,14.4cm和0.17,两种方法计算结果相差不多。再次,利用有限元模型计算了下边界孔压变化、上边界孔压变化条件下的种植土地表开始积水时间,结果表明随着下边界孔压降低,地表开始积水时间延长,随着上边界孔压降低,地表开始积水时间延长,当下边界孔压为0kPa时,初始上边界孔压分别为-6kPa和-12kPa,地表开始积水时间分别为45 min和50 min,地表开始积水时间有一定差异;当初始上边界为-6kPa,下边界分别为0kPa,-1kPa,-2kPa和-3kPa时,地表开始积水时间分别为45min,45min,46min和47min,下边界条件对地表开始积水时间影响较小。地基土渗透系数为6.5×10~(-9) m/s,地基土孔隙水压力分别为0kPa,-4.5kPa,-9kPa,-13.5kPa和-18kPa,利用有限元模型求解获得种植土地表开始积水时间分别为54min,54min,55min,55min和56min,地表积水深度分别为11.9cm,11.7cm,11.5cm,11.4cm和11.3cm,随着地基土孔隙水压力降低,种植土地表开始积水时间略有延长,种植土地表积水深度略有降低,总体上地基土孔隙水压力对种植土地表积水时间和积水深度影响不大。地基土孔隙水压力0kPa,渗透系数分别为6.5×10~(-9) m/s和6.5×10-7 m/s,利用有限元模型计算获得种植土地表开始积水时间均为54 min,积水深度均为11.9cm,地基土渗透系数对种植土地表积水时间和积水深度基本无影响。从上述研究结果可以看出,可以使用平均降雨强度和理论解析法计算地表开始积水时间和积水深度;下边界条件对地表开始积水时间和积水深度影响不大;地基土的饱水渗透系数、地基土的初始含水率对地表积水开始时间和地表积水深度影响不大;使用理论解析解求解种植土-碎石绿化带雨水入渗问题是合理的。     

Cloning of cDNAs for cellular proteins that bind to the retinoblastoma gene product

The E7 transforming protein of human papilloma virus-16 binds to the retinoblastoma gene product (pRb) through a nine-amino-acid segment of E7 (21-29). This segment of E7 is homologous to the pRb-binding domains of the simian virus 40 large T and adenovirus E1A transforming proteins. Each of these viral transforming proteins bind to the same region of pRb. To isolate cellular proteins that interact with this viral protein-binding domain on pRb, we used recombinant pRb to screen a human complementary DNA expression library. Two cDNAs were isolated that encode retinoblastoma binding proteins (RBP-1 and RBP-2). We report here that these RBP genes exist in separate loci and produce discrete messenger RNAs. The predicted amino-acid sequence of these genes showed no homology to known proteins, but both RBPs contain the pRb binding motif conserved between E7, large T and E1A14. In vitro expression of the RBP cDNAs yielded proteins that specifically bound to pRb. Recombinant E7 protein, the E7 21-29 peptide and the homologous RBP-1 peptide inhibited RBP-pRb binding. Mutations introduced into the putative pRb-binding segment in RBP-1 impaired its binding activity. These studies indicate that the cellular RBP-1, RBP-2 and viral E7 proteins interact with pRb through similar domains.     

大肠杆菌磷酸烯醇式丙酮酸羧化酶的克隆和表达

为了更好地研究磷酸烯醇式丙酮酸羧化酶的结构和功能,采用PCR(聚合酶链式反应)、双酶切和细胞转化等基因工程方法对磷酸烯醇式丙酮酸羧化酶基因进行克隆并使用SDS-聚丙烯酰胺凝胶电泳进行表达分析,扩增出一个新的大肠杆菌磷酸烯醇式丙酮酸羧化酶基因,将其基因克隆到原核表达载体pET-30a上,并导入到大肠杆菌表达菌株BL21(DE3)中。通过IPTG诱导成功表达出大肠杆菌的磷酸烯醇式丙酮酸羧化酶。所提出的方法能够高效表达磷酸烯醇式丙酮酸羧化酶,为进一步大规模表达纯化和应用提供参考。     

基于社区森林模型的分布式重叠社区发现算法

重叠社区发现是复杂网络挖掘中的重要基础工作,可以应用于社交网络、通讯网络、蛋白质相互作用网络、代谢路径网络、交通网络等多种网络的数据分析,从而服务智慧交通、传染病防治、舆情分析、新药研制和人力资源管理等领域.传统的单机运算架构已经难以满足各类大规模复杂网络的分析和计算要求.人工智能领域的研究人员提出将社区发现应用到网络...     

解体好氧颗粒污泥修复

考察了加入新的活性污泥使解体好氧颗粒污泥完成修复的可行性.解体好氧颗粒污泥对新加入的活性污泥进行吸附,在各种选择压力特别是水力剪切力作用下和原有颗粒污泥形成一个有机整体.大约3周时间,解体颗粒污泥被完全修复.扫描电镜观察发现,被修复后的颗粒污泥呈现非常规则的结构,微生物相十分致密.在解体颗粒污泥逐渐被修复的过程中,颗粒平均粒径仅从最初的2.8mm增至2.9mm,说明活性污泥在颗粒污泥上的附着主要发生在颗粒的空穴.而颗粒污泥的沉降性能和强度都得到了极大的改善,颗粒沉降速率和完整性系数分别由最初的72m/h和56.8%提高到110m/h和65.8%.新加入的活性污泥除了部分用于修复解体颗粒污泥,其余在选择压力等的作用下形成了新的好氧颗粒污泥.     

Hibernation at moderate temperatures: a continuation of slow wave sleep

Summary Golden-mantled ground squirrels (Citellus lateralis) displayed virtually continuous electrophysiological states of sleep when hibernating at moderate ambient temperatures (22°C). Rapid-eye-movement sleep progressively diminished with the fall in body temperature so that at a body temperature of 23°C it was completely absent. At this temperature hibernation was characterized by slow wave sleep isomorphic with slow wave sleep episodes at non-hibernating (euthermic) body temperatures.Supported by National Institute of Health grants GM 23694 awarded to R.J. Berger and GM 23695 awarded to H.C. Heller.