A collective motion of self-driven particles has been a fascinating subject in physics and biology. Sophisticated macroscopic behavior emerges through a population in thousands or millions of bacterial cells, propelling itself by flagellar rotation and its chemotactic response. Here we found a series of collective motions accompanying successive phase-transitions in a non-flagellated rod-shaped soil bacterium, Flavobacterium johnsoniae , which was driven by a surface cell movement known as gliding motility. When we spot the cells on an agar plate with a low level of nutrients, the bacterial community exhibited vortex patterns that spontaneously appeared as lattice and integrated into a large-scale circular plate. All patterns exhibit with monolayer of bacteria, which enable to visualize an individual cell with a high resolution among a wide-range pattern two-dimensionally. The single cells moved at random orientation, but the cells connected with one another showed left-turn biased trajectories in starved environment. This feature is possibly due to the collision of cells inducing a nematic alignment of dense cells as self-propelled rods. Subsequently, each vortex oscillated independently, and then transformed to the rotating mode as an independent circular plate. Notably, the rotational direction of the circular plate was counterclockwise without exception. The plates developed accompanying rotation with constant angular velocity, suggesting that the mode is an efficient strategy for bacterial survival. Importance Self-propelled bacteria propelled by flagella rotation often display highly organized dynamic patterns at high cell densities. Here we found a new mode of collective motion in non-flagellated bacteria: vortex patterns were spontaneously appeared as lattice and integrated into a large-scale circular plate comprising hundreds of thousands of cells, which exhibited unidirectional rotation in a counterclockwise manner and expanded in size on agar. A series of collective motions was driven by gliding motility of the rod-shaped soil bacterium Flavobacterium johnsoniae . In a low nutrient environment, single cells moved at random orientation while cells at high density moved together as a unitary cluster. This might be an efficient strategy for cells of this species to find nutrients.

Introduction at least 90% of people living with human immunodeficiency virus (HIV) were expected to know their HIV status by 2020. However, only 84% are aware of their status. This study determined the frequency of HIV testing services visits (HTS) and its related factors to HTS visits among adults in Homa Bay County, Kenya. Methods this was a cross-sectional study. Quantitative and qualitative data were collected. A backward stepwise logistic regression analysis was conducted for quantitative data by gender. Qualitative data were thematically categorised into factors of HTS visits by gender. Results a total of 645 adults participated in quantitative survey and 17 in qualitative survey. There were no gender differences in the frequency of HTS visits (males=56.3%; females= 58.7%, P=0.785). The frequency of visits was however significantly different between the rural-based (Rachuonyo North=87.5%; Ndhiwa=58.7%) and urban-based (Homa Bay Town=36.8%) facilities at P<0.001. In males, HTS visits were positively associated with ´being in Protestant church´, ´partner´s attitude´, and ´being accompanied by a friend to HTS´. ´Distance to HTS´ was negatively associated with HTS visits in males. For females, 'sexual intercourse in the past 2-5 months´ was positively associated with HTS visits. ´Being in a polygamous marriage´, ´not married´, ´community HIV testing´, and ´affordability of transport cost to HTS centre´ were negatively associated with HTS visits. Conclusion there were no gender differences in the frequency of HTS visits. Social position for males and position in the family for females are suggested as the factors influencing HTS visits in Homa Bay County.