论文标题

在冰中的生物凝聚和预言

Biolocomotion and premelting in ice

论文作者

Vachier, Jeremy, Wettlaufer, J. S.

论文摘要

在冰川,冰盖和多年冻土中发现了生物群。冰结合的微生物在复杂的移动环境中演变而来,促进或受到一系列散装和表面相互作用的阻碍。将粒子嵌入其大块熔化温度附近的宿主固体中时,在称为界面预言的过程中形成熔融膜在粒子表面形成。在温度梯度下,粒子是由一个被称为热燃料的过程中的热分子压力梯度朝着高温区域驱动的。当宿主固体是冰并且颗粒是生物群时,在其环境中蓬勃发展需要制定策略,例如产生外聚合物质(EPS)和抗冻糖糖蛋白(AFP),从而增强界面水。因此,通过过程{\ em Bio-增强的预启示},通过一个过程来增强和修改热的恢复。此外,生物颗粒的运动受到冰冷宿主体内营养素影响的化学梯度的影响。我们展示了生物颗粒的整体轨迹如何受热化与定向生物振动的竞争。通过在主动Ornstein-uhlenbeck动力学的随机框架中重新估算这类再融合现象,并使用多个量表分析,我们发现,对于有吸引力的(抑制)营养源,通过生物同位素来增强热恢复(抑制)。这种现象在天体生物学,极端粒子的生物签名和陆地古气候学方面很重要。

Biota are found in glaciers, ice sheets and permafrost. Ice bound micro-organisms evolve in a complex mobile environment facilitated or hindered by a range of bulk and surface interactions. When a particle is embedded in a host solid near its bulk melting temperature, a melted film forms at the surface of the particle in a process known as interfacial premelting. Under a temperature gradient, the particle is driven by a thermomolecular pressure gradient toward regions of higher temperatures in a process called thermal regelation. When the host solid is ice and the particles are biota, thriving in their environment requires the development of strategies, such as producing exopolymeric substances (EPS) and antifreeze glycoproteins (AFP) that enhance the interfacial water. Therefore, thermal regelation is enhanced and modified by a process we term {\em bio-enhanced premelting}. Additionally, the motion of bioparticles is influenced by chemical gradients influenced by nutrients within the icy host body. We show how the overall trajectory of bioparticles is controlled by a competition between thermal regelation and directed biolocomotion. By re-casting this class of regelation phenomena in the stochastic framework of active Ornstein-Uhlenbeck dynamics, and using multiple scales analysis, we find that for an attractive (repulsive) nutrient source, that thermal regelation is enhanced (suppressed) by biolocomotion. This phenomena is important in astrobiology, the biosignatures of extremophiles and in terrestrial paleoclimatology.

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