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1.
Lake trout (Salvelinus namaycush) are an ecologically and economically important piscivore with reported differences in diet and feeding behaviour throughout its range. Eleven stomach content and stable isotope-based metrics were used to describe diets of 349 lake trout between two years (2013 and 2018) and among geographic zones (west, central, east, Kingston basin) in Lake Ontario. Using individual (e.g., volumetric, %V) and aggregate (e.g., index of relative importance, %IRI) diet metrics, we found an overwhelming dominance of alewife (Alosa pseudoharengus) in lake trout diets among some zones in 2013 (%V = 23.3 – 92.7; %IRI = 12.2 – 99.5) and all zones in 2018 (%V = 83.9 – 96.7; %IRI = 96.5 – 100). Round goby (Neogobius melanostomus) and rainbow smelt (Osmerus mordax) were secondary lake trout prey items with relative diet percentages only marginally reflected by spatial and temporal variation in prey abundance (round goby: %V = 1.0 – 33.3, %IRI = 0.1 – 13.2; rainbow smelt: %V = 2.5 – 54.0, %IRI = 0.1 – 54.0). Carbon (δ13C) and nitrogen (δ15N) isotopic niche areas and orientations were similar across all year-zone combinations reinforcing temporal and spatial consistency in lake trout diet. The findings of this study advance the time series in describing Lake Ontario lake trout diets and can be used to complement stock assessments and management decisions associated with carrying capacity for the diverse salmonid community.  相似文献   
2.
Under the circumstance of perceptual consumption, it is still challenging to grasp consumer's emotions and demands due to the large search space, diversified preferences, and easy fatigue of consumers. To reduce user fatigue and enlarge search space, a novel method was presented to design and optimize the pattern of yarn-dyed plaid fabric using the isolation niche genetic algorithm and rough set theory. Each pattern was encoded as a chromosome based on the real number code. The population was initialized and evolved using INGA to maintain the diversity. The rough set theory was adopted as the fitness function of isolation niche genetic algorithm to extract the consumer's demands. After multiple evolutions, a large set of practical patterns of the yarn-dyed plaid fabric are obtained. Experiments were carried out by 24 testers of different ages and genders. The results prove that the proposed method based on the isolation niche genetic algorithm and rough set theory is feasible and effective, supplying references to the designer.  相似文献   
3.
为解决产品设计中的公差优化问题,提出一种基于小生境粒子群算法的公差多目标优化方法。以加工成本、质量损失成本和公差敏感性为优化目标,以装配功能要求和加工能力为约束条件,建立了公差多目标优化模型。对标准粒子群算法进行改进,根据小生境数和Pareto优劣性确定孤立粒子,并通过个体历史最优粒子与孤立粒子的变异、选择操作更新粒子的个体历史最优位置;利用Pareto支配数排序更新粒子群的全局最优位置。利用改进的粒子群算法对公差多目标优化模型进行求解,得到分布均匀的Pareto前沿。设计并开发了原型系统,通过实例验证了该方法的有效性。  相似文献   
4.
考虑相关性的间歇性分布式电源选址定容规划   总被引:3,自引:1,他引:2  
节能减排背景下,以分布式风电和光伏为代表的间歇性分布式电源得到了快速发展。考虑风速、光照强度和负荷间的相关性,以年综合费最小为目标,利用机会约束规划方法建立了间歇性分布式电源选址定容规划模型。采用秩相关系数矩阵表征风速、光照强度和负荷间的相关性,利用拉丁超立方采样和Cholesky分解生成相关性样本矩阵。应用动态小生境差分进化算法对规划模型进行求解。IEEE 33节点配电网算例的仿真结果验证了模型的合理性。  相似文献   
5.
Tumor progression to a metastatic and ultimately lethal stage relies on a tumor-supporting microenvironment that is generated by reciprocal communication between tumor and stromal host cells. The tumor–stroma crosstalk is instructed by the genetic alterations of the tumor cells—the most frequent being mutations in the gene Tumor protein p53 (TP53) that are clinically correlated with metastasis, drug resistance and poor patient survival. The crucial mediators of tumor–stroma communication are tumor-derived extracellular vesicles (EVs), in particular exosomes, which operate both locally within the primary tumor and in distant organs, at pre-metastatic niches as the future sites of metastasis. Here, we review how wild-type and mutant p53 proteins control the secretion, size, and especially the RNA and protein cargo of tumor-derived EVs. We highlight how EVs extend the cell-autonomous tumor suppressive activity of wild-type p53 into the tumor microenvironment (TME), and how mutant p53 proteins switch EVs into oncogenic messengers that reprogram tumor–host communication within the entire organism so as to promote metastatic tumor cell dissemination.  相似文献   
6.
为了解根际微生物在间作模式下有效控制土传病害的作用和机理,综述了间作系统对于根际微生物群落结构和代谢功能的影响,介绍了间作作物组合、作物品种选择和间作方式对根际微生物群落的影响,并从养分和宿主感染位点竞争、生防微生物的拮抗作用、植物化感自毒作用的缓解以及植物诱导系统抗性四个方面总结了与根际微生物相关的间作抗病机理。最后,讨论了现阶段间作抗病研究的局限性并对今后的研究方向进行了展望。  相似文献   
7.
信息安全保障对于电力信息物理系统安全稳定运行至关重要,其关键在于对电力信息物理系统进行全方位实时监控,并对采集到的海量监测数据进行分析以做出准确的安全风险评估结果。作为用于模式分类的进化算法,基因表达式编程(gene expression programming,GEP)算法由于其可以执行全局搜索而受到广泛关注,但其在高维度数据集下的运算极为耗时。针对上述问题,提出了一种基于小生境提高样本多样性的改进基因表达式编程算法用于电网信息安全风险评估,该算法首先利用粗糙集的思想,通过分辨函数求解最优属性对数据样本进行约简,再利用小生境模型提高约简样本个体的多样性以加快GEP算法运算的收敛速度,进而通过遗传算法实现全局搜索并得到安全风险等级评估结果。仿真实验表明,与传统的安全风险评估算法相比,提出的改进GEP算法具有较高的属性约简率和全局收敛率,可以快速实现海量监测数据下的电网信息安全风险评估。  相似文献   
8.
Specific stem cell populations within dental mesenchymal tissues guarantee tooth homeostasis and regeneration throughout life. The decision between renewal and differentiation of stem cells is greatly influenced by interactions with stromal cells and extracellular matrix molecules that form the tissue specific stem cell niches. The Cxcl12 chemokine is a general marker of stromal cells and plays fundamental roles in the maintenance, mobilization and migration of stem cells. The aim of this study was to exploit Cxcl12-GFP transgenic mice to study the expression patterns of Cxcl12 in putative dental niches of intact and injured teeth. We showed that endothelial and stromal cells expressed Cxcl12 in the dental pulp tissue of both intact molars and incisors. Isolated non-endothelial Cxcl12+ dental pulp cells cultured in different conditions in vitro exhibited expression of both adipogenic and osteogenic markers, thus suggesting that these cells possess multipotent fates. Taken together, our results show that Cxcl12 is widely expressed in intact and injured teeth and highlight its importance as a key component of the various dental mesenchymal stem cell niches.  相似文献   
9.
米酒乳杆菌是常见的异型发酵乳酸菌,它常常用作肉类工业发酵剂。为了了解其在肉类环境中的生存状况,本文用定量PCR对米酒乳杆菌La22在添加肌浆蛋白和肌原纤维蛋白的培养基中生长时生境适应相关基因表达量进行分析。结果显示,在两种培养基中生长时,p H值均随时间的延长而下降,在添加肌浆蛋白的培养基略高于添加肌原纤维蛋白培养基。与对照相比,在添加肌浆蛋白培养基中的arc A、arc B、arc C、arc T以及添加肌原纤维蛋白培养基中的arc R基因表达量明显上调,其余几个arc基因也均上调,但不明显;压力相关基因lsa00513、usp4以及usp2在肌浆蛋白培养基中均明显上调;有6个ABC转运子基因在添加两种肌肉蛋白的培养基中表达量明显上调。结果表明米酒乳杆菌能通过能量转换与基因表达调节来适应含肉类蛋白的培养环境。  相似文献   
10.
粒子群算法因其形式比较简洁,参数设置灵活,操作简便易行,并且能够快速收敛,从而引起广泛关注。但是传统的粒子群算法也有缺陷:收敛速度慢以及容易陷入局部最优等。针对这些问题,本文借鉴小生境的方法,在进化初始阶段,对种群进行划分,将初始种群分为子种群,对不同的子种群进行不同的变异策略;在进化过程中,针对不同的子种群,设置不同的惯性权重因子ω,用来增强全局搜索能力与局部搜索能力。实验结果表明,本文提出的算法较传统的粒子群算法具有较快的收敛性以及找寻的全局最优解更接近真实解集,收敛精度比较高。  相似文献   
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