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A robust ionospheric model is indispensable for providing the atmospheric delay corrections for global navigation satellite system (GNSS) navigation and positioning and forecasting the space environment. The accuracy of ionospheric models is limited due to the simplified model structures. Complicated spatiotemporal variations in total electron content (TEC) biases between GNSS and international reference ionosphere (IRI) suggest a robust strategy to optimally combine GNSS and IRI TEC for high-precision modeling. In this paper, we propose a novel ionospheric data assimilation method, which is a local ensemble transform Kalman filter (LETKF), to construct an ionospheric model over Yunnan in southwestern China. We used the LETKF method to assimilate the ionospheric TEC extracted from GNSS observations in Yunnan into the IRI-2016 model. The experimental results indicate that the ionospheric data assimilation has a more pronounced improvement effect on the IRI empirical model during periods of geomagnetic quiet than during periods of geomagnetic disturbance. On quiet magnetic days, the skill score (SKS) of the assimilation is 0.60 and the root mean square error (RMSE) values before and after assimilation are 5.08 TECU and 2.02 TECU, respectively. The correlation coefficient after assimilation increases from 0.94 to 0.99. On magnetic storm days, the SKS of the assimilation is 0.42 and the RMSE values before and after assimilation are 5.99 TECU and 3.46 TECU, respectively. The correlation coefficient after assimilation increases from 0.98 to 0.99. The results suggest that the LETKF algorithm can be considered an effective method for ionospheric data assimilation. [ABSTRACT FROM AUTHOR]

Background: The affecting factors of mucocutaneous manifestations in human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS) patients remain unclear in China. Methods: A retrospective analysis was conducted among HIV/AIDS patients in Yunnan, China. The demographic data, mucocutaneous manifestations, CD4 cell counts, and antiretroviral therapy (ART) regimens were collected. The effects of CD4 cell count and ART on the spectrum of mucocutaneous manifestations were evaluated. Results: Among 508 HIV/AIDS patients, 86.0% of cases showed mucocutaneous manifestations. The average CD4 cell count (176 cells/μl) of the patients with manifestations was significantly lower than those without manifestations (328 cells/μl) (P < 0.001). Diseases such as herpes zoster, oral candidiasis, condyloma acuminatum, genital herpes, oral leukoplakia, talaromycosis, cryptococcosis, and HIV‐PPE (pruritic papular eruption) were represented quite frequently in patients with CD4 cell count <200 cells/μl (P < 0.05), but eczema was suffered by those with CD4 cell count ≥200 cells/μl (P < 0.05). ART could decline the incidence of herpes zoster, oral candidiasis, condyloma acuminatum, genital herpes, oral leukoplakia, talaromycosis, and cryptococcosis (P < 0.05). Conclusions: Mucocutaneous manifestations are closely related to the CD4 cell count and can be used as early predictors of HIV/AIDS and immune status in clinic. ART could reduce the incidence of certain mucocutaneous manifestations. [ABSTRACT FROM AUTHOR]