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1.
Seymour B  Dolan R 《Neuron》2008,58(5):662-671
Emotion plays a critical role in many contemporary accounts of decision making, but exactly what underlies its influence and how this is mediated in the brain remain far from clear. Here, we review behavioral studies that suggest that Pavlovian processes can exert an important influence over choice and may account for many effects that have traditionally been attributed to emotion. We illustrate how recent experiments cast light on the underlying structure of Pavlovian control and argue that generally this influence makes good computational sense. Corresponding neuroscientific data from both animals and humans implicate a central role for the amygdala through interactions with other brain areas. This yields a neurobiological account of emotion in which it may operate, often covertly, to optimize rather than corrupt economic choice.  相似文献   

2.
Protein aggregation seems to be a common feature of several neurodegenerative diseases and to some extent of physiological aging. It is not always clear why protein aggregation takes place, but a disturbance in the homeostasis between protein synthesis and protein degradation seems to be important. The result is the accumulation of modified proteins, which tend to form high molecular weight aggregates. Such aggregates are also called inclusion bodies, plaques, lipofuscin, ceroid, or ‘aggresomes’ depending on their location and composition. Such aggregates are not inert metabolic end products, but actively influence the metabolism of cells, in particular proteasomal activity and protein turnover. In this review we focus on the influence of oxidative stress on protein turnover, protein aggregate formation and the various interactions of protein aggregates with the proteasome. Furthermore, the formation and effects of protein aggregates during aging and neurodegeneration will be highlighted.  相似文献   

3.
The structure of social interactions influences many aspects of social life, including the spread of information and behavior, and the evolution of social phenotypes. After dispersal, organisms move around throughout their lives, and the patterns of their movement influence their social encounters over the course of their lifespan. Though both space and mobility are known to influence social evolution, there is little analysis of the influence of specific movement patterns on evolutionary dynamics. We explored the effects of random movement strategies on the evolution of cooperation using an agent-based prisoner’s dilemma model with mobile agents. This is the first systematic analysis of a model in which cooperators and defectors can use different random movement strategies, which we chose to fall on a spectrum between highly exploratory and highly restricted in their search tendencies. Because limited dispersal and restrictions to local neighborhood size are known to influence the ability of cooperators to effectively assort, we also assessed the robustness of our findings with respect to dispersal and local capacity constraints. We show that differences in patterns of movement can dramatically influence the likelihood of cooperator success, and that the effects of different movement patterns are sensitive to environmental assumptions about offspring dispersal and local space constraints. Since local interactions implicitly generate dynamic social interaction networks, we also measured the average number of unique and total interactions over a lifetime and considered how these emergent network dynamics helped explain the results. This work extends what is known about mobility and the evolution of cooperation, and also has general implications for social models with randomly moving agents.  相似文献   

4.
杜卫国  计翔 《生态学报》2002,22(4):548-553
用4个恒定温(24-32℃)孵化灰鼠蛇卵,检测温度对孵化期,孵化成功率和孵出幼体特征的影响。在24-32℃范围内,孵化温度显影响孵化期及孵出幼体的体长和剩余卵黄大小,但不影响孵化成功率和孵出幼体的性别,体重,躯干重和脂肪体重。24,26,30和32℃孵化期分别为99.0,72.2,54.7和48.7d。24℃和26℃孵出幼体的体筮大于30℃和32℃孵出幼体;24℃和32℃孵同幼体内的卵黄较多。不同温度下发育的胚胎对卵内物质和能量的利用一定的差异,但差异不显。雌性幼体的体长,尾长和总长均大于雄性幼体,这些两性差异与孵化温度无关。孵出幼体和新生卵内容的灰分含量无显差异,孵化前后卵壳灰分含量也无显差异,表明灰鼠蛇的卵黄可提供胚胎发育所需的所有无机物。  相似文献   

5.
Electromagnetic fields (EMFs) played a role in the initiation of living systems, as well as subsequent evolution. The more recent literature on electrochemistry is documented, as well as magnetism. The large numbers of reports on interaction with living systems and the consequences are presented. An important aspect is involvement with cell signaling and resultant effects in which numerous signaling pathways participate. Much research has been devoted to the influence of man-made EMFs, e.g., from cell phones and electrical lines, on human health. The degree of seriousness is unresolved at present. The relationship of EMFs to reactive oxygen species (ROS) and oxidative stress (OS) is discussed. There is evidence that indicates a relationship involving EMFs, ROS, and OS with toxic effects. Various articles deal with the beneficial aspects of antioxidants (AOs) in countering the harmful influence from ROS-OS associated with EMFs. EMFs are useful in medicine, as indicated by healing bone fractures. Beneficial effects are recorded from electrical treatment of patients with Parkinson’s disease, depression, and cancer.  相似文献   

6.
Permanent teeth of 12 individuals with a 47,XYY chromosome constitution have been examined. The tooth sizes of 47,XYY males were found to be larger than those of control males and females. In many instances the differences were statistically significant. Using these results, it was possible to conclude that a factor or factors which influence excess growth of 47,XYY males probably are in effect during prenatal life, but without doubt must be in effect very early in postnatal life. The time period needed for the achievement of final excess growth is relatively short, in the case of first permanent molars probably only from 2 1/2 to 3 1/2 years. On the basis of the finding that the Y chromosome apparently carries genes affecting tooth sizes in normal males [1], it was suggested that gene products of the extra Y chromosome could cause the observed size difference between normal and 47,XYY males. The nature of the influence of one versus two Y chromosomes on growth was discussed in terms of the possible influence of the Y chromosome on the cell divisions within the developing tooth germ.  相似文献   

7.
广州桔小实蝇(Bactrocera dorsalis (Hendel))发生动态及气象因子   总被引:1,自引:0,他引:1  
吕欣  韩诗畴  徐洁莲  黄鸿  吴华  欧剑峰  孙力 《生态学报》2008,28(4):1850-1856
2002~2005年期间,在广东广州利用性引诱剂对桔小实蝇进行了全年种群动态监测,调查可知桔小实蝇可在广州全年发生.该虫数量从5月开始迅速上升,6~9月份是发生盛期;10月份虫口密度逐渐下降,11月到翌年3月份种群数量很低.对桔小实蝇发生数量和气象因子进行主成分分析和相关分析,结果表明温雨因子作用最大,其中月平均降雨量是影响桔小实蝇种群变动的关键因子;日照因子作用次之,但月总日照时数对该虫的发生数量没有显著影响.  相似文献   

8.
Climate, energy and diversity   总被引:1,自引:0,他引:1  
In recent years, a number of species-energy hypotheses have been developed to explain global patterns in plant and animal diversity. These hypotheses frequently fail to distinguish between fundamentally different forms of energy which influence diversity in dissimilar ways. Photosynthetically active radiation (PAR) can be utilized only by plants, though their abundance and growth rate is also greatly influenced by water. The Gibbs free energy (chemical energy) retained in the reduced organic compounds of tissue can be utilized by all heterotrophic organisms. Neither PAR nor chemical energy influences diversity directly. Both, however, influence biomass and/or abundance; diversity may then increase as a result of secondary population dynamic or evolutionary processes. Temperature is not a form of energy, though it is often used loosely by ecologists as a proxy for energy; it does, however, influence the rate of utilization of chemical energy by organisms. It may also influence diversity by allowing a greater range of energetic lifestyles at warmer temperatures (the metabolic niche hypothesis). We conclude that there is no single species/energy mechanism; fundamentally different processes link energy to abundance in plants and animals, and diversity is affected secondarily. If we are to make progress in elucidating these mechanisms, it is important to distinguish climatic effects on species' distribution and abundance from processes linking energy supply to plant and animal diversity.  相似文献   

9.
  1. Competitive influence of the isaza population on the ayu population was studied in Lake Biwa.
  2. The results of comparison of ecology of the two species suggest that interaction of ayu and isaza possibly occurs in cold season when there is no other important competitor.
  3. The significance of interspecific competition between them is evaluated as a factor controlling the rate of recruitment of juvenile through analysis of the Pre-war catch statistics.
  4. Presence of the compensation between the juvenile stage and the adult one relieve the ayu population of influence of interspecific competition which they will suffer in the stage of juvenile.
  5. Competitive processes which will be responsible for increase of mortality and reduction of individual growth are discussed.
  相似文献   

10.
Tigan  Galen  Mulvaney  William  Ellison  Luke  Schultz  Andrew  Hung  Tien-Chieh 《Hydrobiologia》2020,847(13):2883-2894
Hydrobiologia - Understanding how environmental factors—here, light intensity and turbidity—influence the feeding, growth, and survival of larval Delta Smelt is critical for optimizing...  相似文献   

11.
Summary The building decision process of the paper wasp,Polistes fuscatus, was studied by 1) analyzing the search pattern of the wasps prior to the addition of pulp to different areas of the nest, 2) comparing the pulp addition needs of the cell chosen for lengthening to those of other cells in the nest, and 3) presenting the wasps with eight types of dichotomous building choices, which provided information about the relative influence of different building cues. Wasps conduct a hierarchical search prior to pulp addition, which means that they search the comb face and petiole disproportionately more often and more thoroughly than the comb back and sides. Once a particular nest area triggers closer scrutiny, comparisons are made with adjoining areas. The most needy location is then chosen based on nest cues. When lengthening a cell, the development of the brood and relative cell length have a strong influence on which cell is chosen at all times, while distance of the brood from the cell mouth becomes important during the later stages of brood development. The results indicate that there is no simple hierarchical weighting of cues. The decision process involves comparisons among multiple cues, which for the most part have an additive influence when variation in relative cue strength is considered.  相似文献   

12.
Summary The influence of a range of pesticides, lime and organic amendments on the level of soil ethylene was determined. Ethylene is important in soils because it can influence the growth of both plants and micro-organisms and thus influence soil fertility. The pesticides used, with the exception of fungicides, had a negligible influence on ethylene production. Fungicide treatment however, led to increased ethylene production. Similar, though more marked increases followed liming, and the addition of chitin, cellulose, urea and barley straw to soil. The results suggest that the action of fungicide in soils is due in part to the secondary production of ethylene following treatment. In the same way increased ethylene production following the addition of lime and organic amendments is likely to influence the activities of both saprophytic and plant pathogenic micro-organisms in the soil. re]19760726  相似文献   

13.
Biodiesel production,properties, and feedstocks   总被引:1,自引:0,他引:1  
Biodiesel, defined as the mono-alkyl esters of vegetable oils or animal fats, is an environmentally attractive alternative to conventional petroleum diesel fuel (petrodiesel). Produced by transesterification with a monohydric alcohol, usually methanol, biodiesel has many important technical advantages over petrodiesel, such as inherent lubricity, low toxicity, derivation from a renewable and domestic feedstock, superior flash point and biodegradability, negligible sulfur content, and lower exhaust emissions. Important disadvantages of biodiesel include high feedstock cost, inferior storage and oxidative stability, lower volumetric energy content, inferior low-temperature operability, and in some cases, higher NO x exhaust emissions. This review covers the process by which biodiesel is prepared, the types of catalysts that may be used for the production of biodiesel, the influence of free fatty acids on biodiesel production, the use of different monohydric alcohols in the preparation of biodiesel, the influence of biodiesel composition on fuel properties, the influence of blending biodiesel with other fuels on fuel properties, alternative uses for biodiesel, and value-added uses of glycerol, a co-product of biodiesel production. A particular emphasis is placed on alternative feedstocks for biodiesel production. Lastly, future challenges and outlook for biodiesel are discussed. Disclaimer: Product names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by USDA implies no approval of the product to the exclusion of others that may also be suitable.  相似文献   

14.
With cardiovascular (CV)-related disorders accounting for the highest mortality rates in the world, affecting the quantity and quality of life of patients and creating an economic burden of prolonged therapeutic intervention, there is great significance in understanding the cellular and molecular alterations that influence the progression of these pathologies. The cellular genotype is regulated by the DNA component, whilst the cellular phenotype is influenced by the protein complement. By improving the understanding of the molecular mechanisms that influence the protein profile, the pathologies that influence the intrinsic functions of the CV system may be detected earlier or managed more efficiently. This is achievable with technologies encompassed by 'proteomics.' Proteomic investigations of CV diseases, including dilated cardiomyopathy (DCM), atherosclerosis, and ischemia/reperfusion (I/R) injury, have identified candidate proteins altered with the pathologic states, complementing past biochemical and physiologic observations. Whilst proteomics is still a relatively new discipline to be applied to the basic scientific investigation of CV diseases, it is emerging as a technique to screen for potential biomarkers in both tissues/cells and biologic fluids (biofluids), as well as to identify the targets of existing therapeutics. By enabling the separation of complex mixtures over numerous dimensions, exploiting the intrinsic properties of proteins, including charge state, molecular mass, and hydrophobicity, in addition to cellular location, the discrete alterations within the cell may be resolved. Proteomics has shown alterations to myofilament proteins including troponin I and myosin light chain, correlating with the reduction in contractility in the myocardium from DCM and I/R. The diverse cell types that coalesce to induce atherosclerotic plaque formation have been investigated both collectively and individually to elucidate the influence of the modifications to single cell types on the developing plaque as a whole. Proteomics has also been used to observe changes to biofluids occurring with these pathologies, a new potential link between basic science and clinical applications. The development of CV proteomics has helped to identify a number of possible protein candidates, and offers the potential to treat and diagnose CV disease more effectively in the future.  相似文献   

15.
为了探讨在热带天然林景观中不同因素对木本植物(限于乔木和灌木)功能型分布的影响,在对海南岛霸王岭的热带天然林进行样方调查的基础上,运用数量分类方法对热带天然林的木本植物进行了功能型划分,并运用冗余度分析(Redundancy analysis, RDA)分别探讨了功能型出现与否、功能型物种丰富度和功能型木本植物多度3个矩阵与环境、空间和干扰因素之间的关系。运用偏冗余度分析对影响功能型分布变化的环境、干扰、空间及其交互作用等因素进行了定量分解。结果表明:利用木材密度和潜在最大高度两个指标划分出的9个功能型,能较好的区分功能型间对生境的适应响应差异;因子分解表明,纯环境、纯人为干扰和混合的环境-人为干扰是影响3个功能型矩阵分布变化的主要因素,纯空间和与空间位置相耦合的因素相对较低;在诸多因子中,干扰类型、地形因子、土壤类型、砂砾含量、土层厚度以及经纬度坐标是影响功能型分布变化的主导因子;RDA排序分析表明,一般来讲,硬木功能型多在生境条件好和远离人为干扰的立地高发生。软木功能型则更多地出现于生境条件恶劣和人为干扰频繁的立地。而中等硬度功能型则生态幅度较宽。但除了软木灌木功能型外,其它功能型物种丰富度和木本植物多度多在土层深厚和生境条件较好的立地较高。  相似文献   

16.
Thioredoxin, a disulfide-containing protein having a highly conservative structure, is present in all types of organisms that are phylogenetically distant from one another. The protein possesses unique capabilities and is universal in respect of physiological functions it performs. In particular, this protein participates in nucleic acid metabolism and thus may protect cells against the lethal influence of gamma-irradiation.  相似文献   

17.
In the Drosophila wing, distal cells signal to proximal cells to induce the expression of Wingless, but the basis for this distal-to-proximal signaling is unknown. Here, we show that three genes that act together during the establishment of tissue polarity, fat, four-jointed and dachsous, also influence the expression of Wingless in the proximal wing. fat is required cell autonomously by proximal wing cells to repress Wingless expression, and misexpression of Wingless contributes to proximal wing overgrowth in fat mutant discs. Four-jointed and Dachsous can influence Wingless expression and Fat localization non-autonomously, consistent with the suggestion that they influence signaling to Fat-expressing cells. We also identify dachs as a gene that is genetically required downstream of fat, both for its effects on imaginal disc growth and for the expression of Wingless in the proximal wing. Our observations provide important support for the emerging view that Four-jointed, Dachsous and Fat function in an intercellular signaling pathway, identify a normal role for these proteins in signaling interactions that regulate growth and patterning of the proximal wing, and identify Dachs as a candidate downstream effector of a Fat signaling pathway.  相似文献   

18.
Neoclassical noncooperative game theory is based on a simple, yet powerful synthesis of mathematical and logical concepts: unconditional and immutable preference orderings and individual rationality. Although this structure has proven useful for characterizing competitive multi-player behavior, its applicability to scenarios involving complex social relationships is problematic. In this paper we directly address this limitation by the introduction of a conditional preference structure that permits players to modulate their preference orderings as functions of the preferences of other players. Embedding this expanded preference structure in a formal and graphical framework provides a systematic approach for characterizing a complex society. The result is an influence network that allows conditional preferences to propagate through the community, resulting in an emergent social model which characterizes all of the social relationships that exist and which leads to solution concepts that account for both group and individual interests. The Ultimatum game is presented as an example of how social influence can be modeled with conditional preferences.  相似文献   

19.
方差是能量的表征,用“方差”作为动物野外“活动量”的度量指标对1981-1982年卧龙五一棚的五只大熊猫无线电跟踪资料(1)进行分析,季节和大熊猫性别对日活动有极显著和显著影响,年活动中,性别显著地影响活动,昼和夜的影响达0.1水准,年龄的影响达0.25水准,应用数量化Ⅰ建立了活动量与性别、季节等变量的回归方程,复相关系数0.81-0.89。  相似文献   

20.
Chance plays a critical but underappreciated role in determining mating success. In many cases, we tend to think of chance as background noise that can be ignored in studies of mating dynamics. When the influence of chance is consistent across contexts, chance can be thought of as background noise; in other cases, however, the impact of chance on mating success can influence our understanding of how mates are acquired and how sexual selection operates. In particular, when the importance of chance covaries with biological or ecological factors in a systematic manner—that is, when chance becomes consistently more or less important under certain conditions—then chance is important to consider if we want to fully understand the operation of mate acquisition and sexual selection. Here, we present a model that explores how chance covaries with factors such as sex ratio, adult population size, and mating regime in determining variation in mating success. We find that in some cases, chance covaries with adult population size and the operational sex ratio to create variation in mating success. We discuss how chance can influence our more general understanding of the operation of mating dynamics and sexual selection.  相似文献   

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