Patch antenna characterization in a high-voltage corona plasma

In order to improve efficiency and reliability of the world's power grids, sensors are being deployed for constant status monitoring. Placing inexpensive wireless sensors on high-voltage power lines presents a new challenge to the RF engineer. Large electric field intensities can exist around a wireless sensor antenna on a high-voltage power line, leading to the formation of a corona plasma. A corona plasma is a partially ionized volume of air formed through energetic electron-molecule collisions mediated by a strong electric field. This corona can contain large densities of free electrons which act as a conducting medium, absorbing RF energy and detuning the sensor's antenna. Through the use of low-profile antennas and rounded geometries, the possibility for corona formation on the antenna surface is greatly reduced, as compared with wire antennas. This study looks at the effects of a corona plasma on a patch antenna, which could be used in a power line sensor. The corona's behavior in the presence of an electromagnetic plane wave is analyzed mathematically to understand the dependence of attenuation on frequency and electron density. A Drude model is used to convert plasma parameters such as electron density and collision frequency to a complex permittivity that can be incorporated in antenna simulations. Using CST Microwave Studio, a 5.8 GHz patch antenna is simulated with a plasma material on its surface, of varying densities and thicknesses. Power absorption by the plasma dominates the power loss, as opposed to detuning. A wideband patch is simulated to show that the detuning effects by the plasma can be further reduced. Power absorption by the plasma is significant for electron densities greater than 10¹⁸ m⁻³. However, small point corona are found to have little effect on antenna radiation.M.S

Effect of priming interval on reactogenicity, peak immunological response, and waning after homologous and heterologous COVID-19 vaccine schedules: exploratory analyses of Com-COV, a randomised control trial

BackgroundPriming COVID-19 vaccine schedules have been deployed at variable intervals globally, which might influence immune persistence and the relative importance of third-dose booster programmes. Here, we report exploratory analyses from the Com-COV trial, assessing the effect of 4-week versus 12-week priming intervals on reactogenicity and the persistence of immune response up to 6 months after homologous and heterologous priming schedules using the vaccines BNT162b2 (tozinameran, Pfizer/BioNTech) and ChAdOx1 nCoV-19 (AstraZeneca).MethodsCom-COV was a participant-masked, randomised immunogenicity trial. For these exploratory analyses, we used the trial's general cohort, in which adults aged 50 years or older were randomly assigned to four homologous and four heterologous vaccine schedules using BNT162b2 and ChAdOx1 nCoV-19 with 4-week or 12-week priming intervals (eight groups in total). Immunogenicity analyses were done on the intention-to-treat (ITT) population, comprising participants with no evidence of SARS-CoV-2 infection at baseline or for the trial duration, to assess the effect of priming interval on humoral and cellular immune response 28 days and 6 months post-second dose, in addition to the effects on reactogenicity and safety. The Com-COV trial is registered with the ISRCTN registry, 69254139 (EudraCT 2020–005085–33).FindingsBetween Feb 11 and 26, 2021, 730 participants were randomly assigned in the general cohort, with 77–89 per group in the ITT analysis. At 28 days and 6 months post-second dose, the geometric mean concentration of anti-SARS-CoV-2 spike IgG was significantly higher in the 12-week interval groups than in the 4-week groups for homologous schedules. In heterologous schedule groups, we observed a significant difference between intervals only for the BNT162b2–ChAdOx1 nCoV-19 group at 28 days. Pseudotyped virus neutralisation titres were significantly higher in all 12-week interval groups versus 4-week groups, 28 days post-second dose, with geometric mean ratios of 1·4 (95% CI 1·1–1·8) for homologous BNT162b2, 1·5 (1·2–1·9) for ChAdOx1 nCoV-19–BNT162b2, 1·6 (1·3–2·1) for BNT162b2–ChAdOx1 nCoV-19, and 2·4 (1·7–3·2) for homologous ChAdOx1 nCoV-19. At 6 months post-second dose, anti-spike IgG geometric mean concentrations fell to 0·17–0·24 of the 28-day post-second dose value across all eight study groups, with only homologous BNT162b2 showing a slightly slower decay for the 12-week versus 4-week interval in the adjusted analysis. The rank order of schedules by humoral response was unaffected by interval, with homologous BNT162b2 remaining the most immunogenic by antibody response. T-cell responses were reduced in all 12-week priming intervals compared with their 4-week counterparts. 12-week schedules for homologous BNT162b2 and ChAdOx1 nCoV-19–BNT162b2 were up to 80% less reactogenic than 4-week schedules.InterpretationThese data support flexibility in priming interval in all studied COVID-19 vaccine schedules. Longer priming intervals might result in lower reactogenicity in schedules with BNT162b2 as a second dose and higher humoral immunogenicity in homologous schedules, but overall lower T-cell responses across all schedules. Future vaccines using these novel platforms might benefit from schedules with long intervals

Antenna Performance in a Corona Plasma

The formation of corona discharges at high potentials was studied. Glow coronas were found to be generated when the electric field magnitude is in excess of 3MV/m in general for air at atmospheric pressure. The number density of electrons in the glow corona can only be approximated, but the results obtained from the Boltzmann transport equation promise to be accurate enough to give meaningful wave attenuation results, so long as the number density is below 1019 m-3 electrons. Above this density, the attenuation increases dramatically and approximations for density may no longer be valid. Wave propagation and antenna parameters in a corona plasma can be computed through simulation using dielectric slabs of complex impedance to simulate a plasma sheath

Deterioro cognitivo, síntomas depresivos y calidad de vida relacionada con la salud en pacientes con insuficiencia cardiaca estable severa

Antecedentes/Objetivo : Las enfermedades cardiovasculares y la depresión son comunes y, muchas veces, coexistentes empeorando la calidad de vida. Además, existen trastornos de funciones cognitivas omnipresentes en pacientes con insuficiencia cardiaca. Se obser - van deficiencias de distinto nivel de severidad en varios dominios cognitivos. Asimismo, en la depresión existen problemas cognitivos que podrían perjudicar el funcionamiento cotidiano, obstaculizar la adaptación a la enfermedad y empeorar los pronósticos. El objetivo de este trabajo fue evaluar la relación entre calidad de vida, intensificación de trastornos depresivos y trastornos de ciertos aspectos de las funciones ejecutivas y me - moria en pacientes con insuficiencia cardiaca grave y estable. Método : Los estudios se realizaron en un grupo de 50 pacientes con insuficiencia cardiaca grave y estable, y otro de 50 pacientes con enfermedad coronaria, pero sin insuficiencia cardiaca. Resultados : Los resultados de las pruebas cognitivas son notablemente peores en el grupo con insufi - ciencia cardiaca en comparación con el grupo control. Se observó una calidad de vida considerablemente peor y unos resultados significativamente más altos en la prueba BDI- II. No se demostró que los trastornos cognitivos influyeran en el empeoramiento de la calidad de vida. Sin embargo, se observó que los síntomas de depresión influían en la calidad de vida. Conclusiones : El factor que afecta significativamente la calidad de vida es la intensificación de los síntomas depresivos