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Background: Perinatally HIV-infected adolescents (PHIVA) are an expanding population vulnerable to loss to follow-up (LTFU). Understanding the epidemiology and factors for LTFU is complicated by varying LTFU definitions. Setting: Asian regional cohort incorporating 16 pediatric HIV services across 6 countries. Methods: Data from PHIVA (aged 10-19 years) who received combination antiretroviral therapy 2007-2016 were used to analyze LTFU through (1) an International epidemiology Databases to Evaluate AIDS (IeDEA) method that determined LTFU as >90 days late for an estimated next scheduled appointment without returning to care and (2) the absence of patient-level data for >365 days before the last data transfer from clinic sites. Descriptive analyses and competing-risk survival and regression analyses were used to evaluate LTFU epidemiology and associated factors when analyzed using each method. Results: Of 3509 included PHIVA, 275 (7.8%) met IeDEA and 149 (4.3%) met 365-day absence LTFU criteria. Cumulative incidence of LTFU was 19.9% and 11.8% using IeDEA and 365-day absence criteria, respectively. Risk factors for LTFU across both criteria included the following: age at combination antiretroviral therapy initiation = 5 years, rural clinic settings compared with urban clinic settings, and high viral loads compared with undetectable viral loads. Age 10-14 years compared with age 15-19 years was another risk factor identified using 365-day absence criteria but not IeDEA LTFU criteria. Conclusions: Between 12% and 20% of PHIVA were determined LTFU with treatment fatigue and rural treatment settings consistent risk factors. Better tracking of adolescents is required to provide a definitive understanding of LTFU and optimize evidence-based models of care.

We study the electronic structure of NaCuO2 by analysing experimental core level photoemission and X-ray absorption spectra using a cluster as well as an Anderson impurity Hamiltonian including the band structure of the oxygen sublattice. We show that the X-ray absorption results unambiguously establish a negative value of the charge transfer energy, A. Further, mean-field calculations for the edge-shared one-dimensional CuO2 lattice of NaCuO2 within the multiband Hubbard Hamiltonian show that the origin of the insulating nature lies in the band structure rather than in the correlation effects. LMTO-ASA band structure calculations suggest that NaCuO2 is an insulator with a gap of around 1 eV.