With the advent of post-epidemic era, China's tourism industry has increased significantly. So there is a need for large number people who are proficient in travel English. However, training professionals China somewhat backward. This paper analyzes problems existing listening and speaking teaching Tourism English higher vocational colleges, applies schema theory to this application colleges fr...

Many of the remaining challenges in infectious disease control involve pathogens that fail to elicit long-lasting immunity in their hosts. Antigenic variation is a common reason for this failure and a contributor to the complexity of vaccine design. Diversifying selection by the host immune system is commonly, and often correctly, invoked to explain antigenic variability in pathogens. However, ...

We present a novel model that describes the within-host evolutionary dynamics of parasites undergoing antigenic variation. The approach uses a multi-type branching process with two types of entities defined according to their relationship with the immune system: clans of resistant parasitic cells (i.e. groups of cells sharing the same antigen not yet recognized by the immune system) that may be...