Short-range interactions versus long-range correlations in bird flocks
Short-range interactions versus long-range correlations in bird flocks
复制标题
DOI：
10.1103/physreve.92.012705
复制
发表时间：
2015-07-06
影响因子：
2.4
通讯作者：
Viale, Massimiliano
中科院分区：
文献类型：
--
作者：
Cavagna, Andrea;Del Castello, Lorenzo;Viale, Massimiliano
鸟群是集体运动的典型例子。群集的一个显著特征是个体之间存在长距离的速度相关性，这使得它们能够在大范围内相互影响，保持高水平的群体协调。一个至关重要的问题是要了解鸟类之间的相互作用是什么产生了如此重要的相关性。在这里，我们使用的最大熵（ME）的方法来推断从自然羊群的实验数据的有效的个人之间的相互作用。与之前的研究相比，我们向前迈出了重要一步，因为我们检索了相互作用对距离的完整功能依赖性，并发现它在几个人的范围内呈指数级衰减。ME给出了一个短程相互作用的事实，即使它的实验输入是长程相关函数，表明该方法能够区分编码在这种相关性的相关信息，并挑选出最少数量的有效参数。最后，我们展示了如何使用该方法来捕获相互作用的各向异性程度。
Bird flocks are a paradigmatic example of collective motion. One of the prominent traits of flocking is the presence of long range velocity correlations between individuals, which allow them to influence each other over the large scales, keeping a high level of group coordination. A crucial question is to understand what is the mutual interaction between birds generating such nontrivial correlations. Here we use the maximum entropy (ME) approach to infer from experimental data of natural flocks the effective interactions between individuals. Compared to previous studies, we make a significant step forward as we retrieve the full functional dependence of the interaction on distance, and find that it decays exponentially over a range of a few individuals. The fact that ME gives a short-range interaction even though its experimental input is the long-range correlation function, shows that the method is able to discriminate the relevant information encoded in such correlations and single out a minimal number of effective parameters. Finally, we show how the method can be used to capture the degree of anisotropy of mutual interactions.