臺灣博碩士論文加值系統

細菌演化出奔跑(run)和翻滾(tumble)這兩種不同的運動模式，以便找到更有利的生存環境。這些運動狀態主要由內部蛋白質控制。除此之外研究上觀察到，奔跑和翻滾的細菌在固體邊界處表現出特別的運動行為。在本篇論文中，模擬趨向化細菌在具有固定隨機圓形障礙物的二維環境中的運動，來研究細菌在其自然環境中遇到的隨機固體邊界的影響。結果顯示，當障礙物邊界之間的平均距離足夠小時，固體邊界的影響使得細菌更有利於找到合適的生存環境。另一方面，在障礙物密度較小的情況下，隨著障礙物密度的增加趨化運動變慢。障礙物邊界之間存在一個平均臨界距離，在此距離時趨向化運動具有最小的平均速度。我們的結果提出了一種透過操縱環境的障礙物密度來控制細菌行為的方法。

Run-and-tumble bacteria have evolved two distinct modes of movement in order to navigate toward more favorable living environments. These movement states are primarily controlled by internal proteins. Additionally, it has been observed that run-and-tumble bacteria exhibit distinctive moving behaviors at solid boundaries. In this thesis, the motion of a chemotactic bacterium in a two-dimensional environment with immobile random circular obstacles is simulated to study the effect of random solid boundaries that a bacterium encounters in its natural environment. The results show that when the average distance between the obstacle walls is sufficiently small, the influence of the solid boundaries makes it more advantageous for bacteria to find a suitable environment for survival. On the other hand, the chemotactic motion in the limit of small densities of obstacles is slower as the density of obstacles increases. There is a critical average distance between the obstacle walls at which the chemotactic motion has the smallest average velocity. Our results suggest a way to control bacterial behavior by manipulating the randomness of the environment.

1 Introduction 1
1.1 acterium-wall interaction 5
2 Model 6
2.1 Equations of motion 6
2.2 Transitions between different moving states 7
2.3 Receptor activation and methylation level 8
2.4 Arranging solid disks in the simulation box 11
3 Results: average velocity of run-and-tumble particles in random environments 17
3.1 elocity and Effective Channel Width 17
3.2 Two possible mechanisms that leads to the vx − Weff relation at Weff < Wth 19
3.2.1 Total tumbling time versus Weff 20
3.2.2 Path length versus Weff 21
3.3 Probability of moving toward regions with higher chemoattractant concentration 22
4 Summary 27

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