Objective To study stability of the deterministic tumor-immune system with time delay by means of linear stability analysis method. Methods In tumor-immune system, since it took some time for immune cells to recognize tumor cells and respond appropriately, time delay was considered in this process, then the model was simplified by using Taylor expansion of small delay, and the equilibrium points were solved out. By linear stability analysis method, the stability of these equilibrium points was studied. Finally, the trajectory of the system and that around each equilibrium point were simulated by numerical calculation method, so as to verify the result of theoretical analysis. Results The system had four meaningful equilibrium points with small delay, including a stable focus, a stable node, and two saddles. Moreover, the type and stability of these equilibrium points were not affected by the delay. Numerical simulation demonstrated the conclusion from theoretical analysis. Conclusions Under the condition of small delay, the type and stability of equilibrium points in the system are notaffected by the delay. The results are helpful to further understand dynamic mechanisms of tumor immune response, and provide references for tumor growth and treatment

OBJECTIVE To establish an evaluation syste m of clinical effec tiveness of Drug Selection Guideline for Medical Institutions，and to provide reference for drug selection in medical institution. METHODS Retrieved from relevant Chinese government websites ，PubMed，Embase，CBM and CNKI ，etc.，from the inception to Sept. 14th 2021，related contents of clinical effectiveness related to three secondary indicators ，such as “recommended level and strength of guideline ”“clinical pathway ”and “evidence and level of efficacy ”were extracted respectively ；evaluation system was construction for the clinical effectiveness. RESULTS A total of 5，4 and 17 policy documents or literatures were included according to “recommended level and strength of guideline”“clinical pathway ”and“evidence and level of efficacy ”，respectively.“The recommended level and strength of drug guideline”could reflect the clinical effectiveness of drugs ，and the evaluation content referred to the recommended level and strength of the selected drugs in the guidelines for corresponding indications. “Clinical pathway ”was the embodiment of drug effectiveness, and the evaluation content referred to the clinical path of whether the selected drugs were included in the corresponding indications. The evaluation contents of “evidence and level of efficacy ”were different between chemical medicine/ biological agent and Chinese patent medicine ；evidence and quality level of efficacy research for chemical medicine/biological agent referred to GRADE system ，while those for Chinese patent medicine referred to classic works or clinical experience inheritance. Therefore，the evaluation contents of this index system were the evidence and quality level of the efficacy research related to selected drugs. CONCLUSIONS The evaluation system of clinical effectiveness of drugs constructed from the perspective of drug selection in medical institutions can lay the foundation of evaluation system for the construction of Drug Selection Guideline for Medical Institutions ，and also provide reference for drug selection in medical institutions.

The gut microbiome shows changes under a plateau environment, while the disbalance of intestinal microbiota plays an important role in the pathogenesis of irritable bowel syndrome (IBS); however, the relationship between the two remains unexplored. In this work, we followed up a healthy cohort for up to a year before and after living in a plateau environment and performed 16S ribosomal RNA (rRNA) sequencing analysis of their fecal samples. Through evaluating the participants' clinical symptoms, combined with an IBS questionnaire, we screened the IBS sub-population in our cohort. The sequencing results showed that a high-altitude environment could lead to changes in the diversity and composition of gut flora. In addition, we found that the longer the time volunteers spent in the plateau environment, the more similar their gut microbiota composition and abundance became compared to those before entering the plateau, and IBS symptoms were significantly alleviated. Therefore, we speculated that the plateau may be a special environment that induces IBS. The taxonomic units g_Alistipes, g_Oscillospira, and s_Ruminococcus_torques, which had been proved to play important roles in IBS pathogenesis, were also abundant in the IBS cohort at high altitudes. Overall, the disbalance of gut microbiota induced by the plateau environment contributed to the high frequency of IBS and the psychosocial abnormalities associated with IBS. Our results prompt further research to elucidate the relevant mechanism.