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相关概念视频

Altruism01:03

Altruism

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Altruistic behaviors are “unselfish” behaviors—those that help another individual at the expense of the individual carrying out the behavior. Despite the negative consequences for the altruistic animal, these behaviors are thought to have evolved for several reasons.
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Egoism and Altruism01:55

Egoism and Altruism

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Voluntary behavior with the intent to help other people is called prosocial behavior. Why do people help other people? Is personal benefit such as feeling good about oneself the only reason people help one another?
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Volatilization01:10

Volatilization

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Volatilization gravimetry is an analytical technique that measures the mass lost due to the volatilization of the substance. This technique is used to estimate the amount of volatile material in a sample. To perform this method, heat a known amount of the sample to a high temperature in a crucible or other suitable vessel. The volatile substance in the sample evaporates, and the vapor is completely expelled from the crucible either by heating the sample or bubbling a stream of inert gas through...
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Freezing Point Depression and Boiling Point Elevation03:12

Freezing Point Depression and Boiling Point Elevation

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Boiling Point Elevation
The boiling point of a liquid is the temperature at which its vapor pressure is equal to ambient atmospheric pressure. Since the vapor pressure of a solution is lowered due to the presence of nonvolatile solutes, it stands to reason that the solution’s boiling point will subsequently be increased. Vapor pressure increases with temperature, and so a solution will require a higher temperature than will pure solvent to achieve any given vapor pressure, including one...
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Vapor Pressure Lowering03:28

Vapor Pressure Lowering

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The equilibrium vapor pressure of a liquid is the pressure exerted by its gaseous phase when vaporization and condensation are occurring at equal rates:
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Vapor Pressure02:34

Vapor Pressure

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When a liquid vaporizes in a closed container, gas molecules cannot escape. As these gas phase molecules move randomly about, they will occasionally collide with the surface of the condensed phase, and in some cases, these collisions will result in the molecules re-entering the condensed phase. The change from the gas phase to the liquid is called condensation. When the rate of condensation becomes equal to the rate of vaporization, neither the amount of the liquid nor the amount of the vapor...
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相关实验视频

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Measuring Volatile and Non-volatile Antifungal Activity of Biocontrol Products
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Measuring Volatile and Non-volatile Antifungal Activity of Biocontrol Products

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在一个不稳定的世界里

Patrick Kennedy1, Andrew D Higginson2, Andrew N Radford1

  • 1School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK.

Nature
|March 8, 2018
PubMed
概括

利他主义或昂贵的自我牺牲可以通过减少亲属的环境变化而演变,即使平均成功率较低. 这种投注对冲策略在不可预测的自然环境中增强了包容性.

科学领域:

  • 进化生物学
  • 行为生态学
  • 人口遗传学

背景情况:

  • 利他主义的演变,定义为为他人付出代价的自我牺牲, 仍然是生物学中的一个重要问题.
  • 现有的理论,如包容性健康和汉密尔顿法则,主要关注平均生殖成功,并且经常忽视环境变化.
  • 经验观察将利他主义与环境随机性联系在一起,这种模式并未完全得到当前模型的解释.

研究的目的:

  • 通过结合环境随机性来重新评估汉密尔顿的规则.
  • 在可变条件下开发利他主义演变的新预测.
  • 探索投注策略与利他行为演变之间的联系.

主要方法:

  • 根据汉密尔顿法则,明确考虑随机性.
  • 分析减少后代变异性对基因型成功的影响的数学建模.
  • 与波动性抑制相关的选择性压力的分析.

主要成果:

  • 利他主义行为可以通过稳定亲属产生的后代数量来演变,从而增加长期的基因型成功.
  • 昂贵的利他主义甚至会降低接受者的平均生殖成功率.
  • 抑制波动性的利他主义选择性压力与人口健康的变化成正比.

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结论:

  • 环境的随机性是理解利他主义演变的关键因素.
  • 利他主义可以作为一种投注对冲策略, 通过降低风险增强健康.
  • 这项研究揭示了与社会行为的演变相关的前所未有的健康效应.