分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-04-30
摘要: Transverse mode-coupling instability (TMCI) is a dangerous transverse single-bunch instability that can leadto severe particle loss. The mechanism of TMCI can be explained by the coupling of transverse coherentoscillation modes owing to the transverse short-range wakefield (i.e., the transverse broadband impedance).Recent studies on future circular colliders, e.g., FCC-ee, showed that the threshold of TMCI decreased significantlywhen longitudinal and transverse impedances were included. We performed computations for a circularelectron-positron collider (CEPC) and observed a similar phenomenon. Systematic studies on the influence oflongitudinal impedance on the TMCI threshold were conducted. We concluded that the imaginary part of thelongitudinal impedance, which caused a reduction in the incoherent synchrotron tune, was the primary reasonfor the reduction in the TMCI threshold. Additionally, the real part of the longitudinal impedance assists inincreasing the TMCI threshold.
分类: 生物学 >> 生物物理学 >> 免疫学 提交时间: 2016-05-11
摘要: Microbiota-mediated effects on the host immune response facilitate colonization resistance against pathogens. However, it is unclear whether and how the host immune response can regulate the microbiota to mediate colonization resistance. ID2, an essential transcriptional regulator for the development of innate lymphoid cell (ILC) progenitors, remains highly expressed in differentiated ILCs with unknown function. Using conditionally deficient mice in which ID2 is deleted from differentiated ILC3s, we observed that these mutant mice exhibited greatly impaired gut colonization resistance against Citrobacter rodentium. Utilizing gnotobiotic hosts, we showed that the ID2-dependent early colonization resistance was mediated by interleukin-22 (IL-22) regulation of the microbiota. In addition to regulating development, ID2 maintained homeostasis of ILC3s and controlled IL-22 production through an aryl hydrocarbon receptor (AhR) and IL-23 receptor pathway. Thus, ILC3s can mediate immune surveillance, which constantly maintains a proper microbiota, to facilitate early colonization resistance through an ID2-dependent regulation of IL-22.