叶生长场的间歇性
The Intermittent Nature of Leaf Growth Fields
摘要：
什么是允许组织或器官正常生长的一般原则？一片生长中的叶子就是这样一个系统的例子：它以数量级增加其面积，保持适当的（通常是平坦的）形状。如果没有中央控制单元，如何实现这一目标？人们会认为，均匀生长与粘弹性流变学的结合将允许这种情况。在这里，我们表明，完全相反的过程是在行动：自然生长的叶片表面强烈波动的时间和位置。通过结合高分辨率的测量和多尺度的统计分析，我们提出了一个范式的变化，叶片生长的方式被认为是。本文在三维拉格朗日坐标系下测量了烟草叶片的面内生长，研究了与张量生长场相关的三个标量场的统计特性：生长速率、各向同性和方向性。我们确定了增长率波动的时间和长度尺度，并在高分辨率测量时捕获局部区域膨胀和收缩之间的大量切换。在较低的时空分辨率下，生长速率场变得平滑。相反，各向异性场随时间增加。最后，我们发现白天和晚上测量的生长之间存在显着差异。在夜间的增长被发现是更间歇性的，与较短的相关长度和没有全球的方向性。尽管生长场具有波动性，但它不是随机的，因此携带着生长调节的信息。事实上，机械分析表明，只有当测量到的波动被调节/相关时，生长的叶子才能保持平坦。我们的测量结果表明，整个统计增长领域，而不仅仅是他们的手段，应该加以研究。特别是，这些领域的监管和他们的特点之间的联系和全球几何形状的一片叶子应该进行研究。
英文摘要：
What are the general principles that allow proper growth of a tissue or an organ? A growing leaf is an example of such a system: it increases its area by orders of magnitude, maintaining a proper (usually flat) shape. How can this be achieved without a central control unit? One would think that a combination of uniform growth with viscoelastic rheology would allow that. Here we show that that the exact opposite process is in action: the natural growth of the leaf surface strongly fluctuates in time and position. By combining high resolution measurements and multi-scale statistical analysis, we suggest a paradigm-change in the way leaf growth is viewed. We measure the in-plane tissue growth of Tobacco leaves in Lagrangian coordinates in 3D and study the statistics of three scalar fields associated with the tensorial growth field: The growth rate, its isotropy and directionality. We identify the governing time and length scales of the fluctuations in the growth rate, and capture abundant switching between local area swelling and shrinking, when measured in high resolution. At lower spatio-temporal resolution the growth rate field becomes smooth. In contrast, the anisotropy field increases over time. Finally, we find significant differences between growth measured during day and night. The growth at night is found to be more intermittent, with shorter correlation lengths and no global directionality. Despite its fluctuative nature, growth fields are not random, thus carry information about growth regulation. Indeed, mechanical analysis shows that a growing leaf can stay flat only if the measured fluctuations are regulated/correlated. Our measurements suggest that the entire statistics of growth fields, and not just their means, should be studied. In particular, the regulation of such fields and the link between their characteristics and the global geometry of a leaf should be studied.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
