Tunable ultra-broadband terahertz metamaterial absorber based on vanadium dioxide strips.

A simple design of an ultra-broadband metamaterial absorber (MMA) of terahertz (THz) radiation based on vanadium dioxide (VO2) configurations is proposed. The system is composed of a top pattern representing orderly distributed VO2 strips, a dielectric spacer and an Au reflector. Theoretical analysis based on the electric dipole approximation is performed to characterize the absorption and scattering properties of an individual VO2 strip. The results then are used to design an MMA composed of such configurations. It is shown that the efficient absorption characteristics of the Au-insulator-VO2 metamaterial structure can be ensured in a broad spectrum of 0.66-1.84 THz with an absorption band relative to the center frequency reaching as high as 94.4%. The spectrum of the efficient absorption can be easily tuned via the corresponding choice of strip dimensions. Wide polarization and incidence angle tolerance for both transverse electric (TE) and transverse magnetic (TM) polarizations are ensured by adding an identical parallel layer rotated by 90 degrees in respect to the first one. Interference theory is applied to elucidate the absorption mechanism of the structure. The possibility of modulation of the electromagnetic response of MMA relying on the tunable THz optical properties of VO2 is demonstrated.

Factors associated with unfavourable treatment outcomes in people with HIV-associated tuberculosis in Armenia, 2015 to 2019.

To evaluate factors associated with tuberculosis (TB) treatment outcomes in human Immunodeficiency Virus-Associated (HIV) TB patients in Armenia, we conducted a nation-wide cohort study using routine programmatic data of all HIV-associated TB patients receiving TB treatment with first- or second-line drugs from 2015 to 2019. Data were obtained from the TB and HIV electronic databases. We analysed occurrence of the combined unfavourable outcome (failure, lost to follow-up, death and not evaluated) and death separately, and factors associated with both outcomes using Cox regression. There were 320 HIV-associated TB patients who contributed a total of 351 episodes of TB treatment. An unfavourable TB treatment outcome was registered in 155 (44.2%) episodes, including 85 (24.2%) due to death, 38 (10.8%) lost to follow up, 13 (3.7%) failure and 19 (5.4%) not evaluated. Multivariable analysis showed that receipt of Antiretroviral Treatment (ART) [ART start before TB treatment: adjusted hazard ratio (aHR)=0.3, 95% confidence interval (CI): 0.2-0.5, aHR=, 95% CI:, 95% CI:, 95% CI:TB meningitis (aHR=4.4, 95% CI: 1.6-11.9) increased the risk. The risk of death was affected by the same factors as above in addition to the low BMI (aHR=2.5, 95% CI: 1.3-4.5) and drug resistance (aHR=2.3, 95% CI: 1.0-5.4). In the subsample of episodes receiving ART, history of interruption of ART during TB treatment increased the risk of unfavourable outcome (aHR=2.1 95% CI: 1.2-3.9), while ART start during TB treatment was associated with lower risk of both unfavourable outcome (within first 8 weeks: aHR: 0.5, 95% CI: 0.3-0.9; after 8 weeks: aHR: 0.4, 95% CI: 0.2-1.0) and death (within first 8 weeks: aHR: 0.2, 95% CI: 0.1-0.4; after 8 weeks: aHR: 0.1, 95% CI: 0.01-0.3). The rates of unfavourable TB treatment outcomes, and death in particular, among HIV-associated TB patients in Armenia are high. Our findings emphasize the protective effect of ART and the importance of proper management of cases complicated by drug resistance or meningitis.

CNS sites cooperate to detect duplicate subjects with a clinical trial subject registry.

OBJECTIVE: To report the results of the first 1,132 subjects in a pilot project where local central nervous system trial sites collaborated in the use of a subject database to identify potential duplicate subjects. METHOD: Central nervous system sites in Los Angeles and Orange County, California, were contacted by the lead author to seek participation in the project. CTSdatabase, a central nervous system-focused trial subject registry, was utilized to track potential subjects at pre-screen. Subjects signed an institutional review board-approved authorization prior to participation, and site staff entered their identifiers by accessing a website. Sites were prompted to communicate with each other or with the database administrator when a match occurred between a newly entered subject and a subject already in the database. RESULTS: Between October 30, 2011, and August 31, 2012, 1,132 subjects were entered at nine central nervous system sites. Subjects continue to be entered, and more sites are anticipated to begin participation by the time of publication. Initially, there were concerns at a few sites over patient acceptance, financial implications, and/or legal and privacy issues, but these were eventually overcome. Patient acceptance was estimated to be above 95 percent. Duplicate Subjects (those that matched several key identifiers with subjects at different sites) made up 7.78 percent of the sample and Certain Duplicates (matching identifiers with a greater than 1 in 10 million likelihood of occurring by chance in the general population) accounted for 3.45 percent of pre-screens entered into the database. Many of these certain duplicates were not consented for studies because of the information provided by the registry. CONCLUSION: The use of a clinical trial subject registry and cooperation between central nervous system trial sites can reduce the number of duplicate and professional subjects entering clinical trials. To be fully effective, a trial subject database could be integrated into protocols across pharmaceutical companies, thereby mandating site participation and increasing the likelihood that duplicate subjects will be removed before they enter (and negatively affect) clinical trials.