Developmental temperature affects phenotypic means and variability: A meta‐analysis of fish data

Fishes are sensitive to their thermal environment and face an uncertain future in a warming world. Theoretically, populations in novel environments might express greater levels of phenotypic variability to increase the chance of surviving—and eventually thriving—in the new conditions. Most research on the effect of the early thermal environment in fish species focuses on average phenotypic effects rather than phenotypic variability, but to understand how fishes will respond to rising temperatures we need to consider both the average response of the population, as well as the breadth of individual responses. Here we present the first meta‐analysis on the effects of developmental temperature in fishes. Using data from 43 species and over 6,000 individual fish, we show that a change in developmental temperature induces a significant change in phenotypic means and variability, but differently depending on whether the temperature is increased or decreased. Decreases in temperature (cool environments) showed a significant decrease in phenotypic means and no change in phenotypic variability. Increases in temperature (warm environments) showed a non‐significant increase in phenotypic means and a marginally significant increase in phenotypic variability. Larger increases in temperature saw greater increases in phenotypic variability, but no increase in the mean phenotypic response. Together, our results suggest that fishes exhibit both directed and stochastic developmental plasticity in response to warming temperatures, which could facilitate or accelerate adaptation to a changing environment.     

大型喷杆喷雾机钟摆式主被动悬架自适应鲁棒控制研究

针对大型喷雾机喷杆钟摆式主被动悬架系统存在的参数不确定性和随机干扰导致控制精度低、稳定性差的问题，对基于模型补偿的自适应鲁棒控制算法进行研究。建立了钟摆式主被动悬架的非线性动力学模型和调节机构几何方程，基于模型设计了自适应鲁棒控制器，综合悬架系统和电液位置伺服系统模型中存在的参数不确定性，同时兼顾系统未补偿的摩擦力和外部扰动等不确定非线性因素，通过理论分析和试验证明，在同时存在模型参数不确定和不确定非线性的情况下，设计的控制器可以保证系统输出跟踪控制的暂态性能和稳态精度。以单出杆液压作动器驱动的28m大型喷杆主被动悬架为例，借助建立的大型喷杆悬架半实物仿真平台进行了控制算法的试验验证，并使用Stewart六自由度运动平台模拟底盘的运动干扰，与反馈线性化控制器、鲁棒反馈控制器、PID控制器进行了试验对比，结果表明，设计的基于模型补偿的自适应鲁棒控制器最大跟踪误差0.148°，而反馈线性化控制器最大跟踪误差0.201°，鲁棒反馈控制器最大跟踪误差0.51°，PID控制器最大跟踪误差0.48°。设计的控制器在同时存在参数不确定性和扰动的情况下，使用较小的反馈增益能够保证渐进跟踪性能和稳态跟踪精度。     

UV-B对紫叶生菜生长及品质的影响初探

为探讨UV-B在植物工厂紫叶生菜水培种植中的应用,本实验在红蓝组合光中添加不同强度的UV-B,研究对紫叶生菜生长及品质的影响。结果表明：随着UV-B强度的增加,紫叶生菜株高及地上鲜重受到显著抑制。高强度下UV-B辐射会降低紫叶生菜可溶性糖和Vc含量,显著增加花青素及总酚含量,提高抗氧化能力。UV-B辐射可以加深紫叶生菜颜色,对鲜重会产生抑制,需要进一步减少辐射时间。     

定量泵负载敏感系统卸荷压力冲击抑制研究

定量泵负载敏感系统在快速卸荷时容易出现压力冲击现象,对系统的可靠性和寿命产生较大危害。三通压力补偿阀是定量泵负载敏感系统中关键的调压元件,本文以三通压力补偿阀为切入点,建立定量泵负载敏感系统功率键合图模型,基于键合图模型推导系统的状态方程,建立Matlab动态仿真模型,探讨系统卸荷压力冲击的抑制方案。基于系统仿真模型,首先对系统卸荷压力冲击的仿真与试验进行对比,验证了仿真模型的正确性;然后,针对三通压力补偿阀的系统压力腔阻尼、阀芯直径、Ls腔阻尼、阀口锥角等关键参数,对卸荷压力冲击影响规律进行仿真;最后,基于关键参数对卸荷压力冲击影响规律的分析,提出了一种"小阀芯、双阀口"型三通压力补偿阀结构优化方案,并对其卸压冲击抑制效果进行了仿真和试验。结果表明,该方案可以有效抑制卸荷压力冲击,优化后系统卸压冲击压差比原系统降低了89%,卸荷压力降低了20%,进一步实现了节能。     

南水北调中线工程生态补偿计算研究

跨流域调水生态补偿的计算方法和考虑因素直接影响着受水区在调水工作中的参与热情.本研究以南水北调陕西汉中、安康、商洛水源区及京、津、冀、豫受水区为研究区,在考虑水源区水土保持建设、受水区水市场情况、水源区水资源价值、水源区排污权损失价值基础上,加入未来水资源调度机会成本、市民意愿支付差价占比及意愿支付补偿额占比,重新计算生态补偿总量.得陕西水源区当前可计算的受水区补偿额为62.42亿元/年.为发展中南水北调中线工程生态补偿计算提供新的计算思路和方法.     

Accessory corpora lutea formation in pregnant Hokkaido sika deer (Cervus nippon yesoensis) investigated by examination of ovarian dynamics and steroid hormone concentrations

Generally, sika deer conceive a single fetus, but approximately 80% of pregnant females have two corpora lutea (CLs). The function of the accessory CL (ACL) is unknown; moreover, the process of ACL formation is unclear, and understanding this is necessary to know its role. To elucidate the process of ACL formation, the ovarian dynamics of six adult Hokkaido sika deer females were examined ultrasonographically together with peripheral estradiol-17β and progesterone concentrations. ACLs formed in three females that conceived at the first estrus of the breeding season, but not in those females that conceived at the second estrus. After copulation, postconception ovulation of the dominant follicle of the first wave is induced by an increase in estradiol-17β, which leads to formation of an ACL. A relatively low concentration of progesterone after the first estrus of the breeding season is considered to be responsible for the increase in estradiol-17β after copulation.     

中央森林生态效益补偿实施中的问题与对策探讨

根据中央森林生态效益补偿实施的现状，从政策、管理、机制等方面分析实施中存在的问题．提出解决问题的对策措施。     

环境再生产与森林生态效益补偿

1　立论的着力点林业发展过程中 ,生态与经济的矛盾、森林利用与环境保护之间的矛盾、国家利益与森林经营者个人利益之间的矛盾、生态系统恢复和森林可持续经营过程中巨大的资金需求与供给严重不足的矛盾随处可见 ,上述矛盾相互交织已经严重影响到林业产业的健康发展 ,影响到森林资源的有效保护和生态环境的维持与改善。因此 ,综合采取技术、经济、管理、法律等手段从根本上解决生态环境保护和建设中所带来的矛盾和困难已经刻不容缓。其中建立森林生态效益补偿制度 ,理顺和协调森林所有者、经营者与受益者的利益关系 ,为林业发展提供稳定的…     

北京市高保护价值森林价值评估理论与方法初探

结合现行经济学理论界对森林价值的评估，针对高保护价值森林的特征，从生物多样性和生态服务功能两方面对北京市高保护价值森林的价值评估方法进行探讨。结合效用论、边际效益论等理论，根据实地情况，运用支付意愿法、补偿法、替代法等，从森林的实用价值和精神文化价值等方面作了评估方法概述。     

国外社区参与生态补偿的实践及经验

本文介绍了其他国家农村社区参与生态补偿的做法及主要经验,以期为我国社区参与生态补偿提供一些借鉴.