571 research outputs found
Effects of long rarefied plasma on fast electron generation for FIREX-I targets
Long-scale preformed plasmas are generated inside the cone by the pre-pulse of the heating laser in the cone-guided fast ignition scheme and it is found that coupling efficiency from the heating laser to fast electrons especially suitable for core heating is drastically reduced by the preformed plasmas. To mitigate this serious problem, an extremely thin film is suggested to cover the entrance of the cone. This method, however, introduces long rarefied plasmas around the entrance of the cone and the main pulse must propagate through these plasmas. Therefore, fast electron characteristics produced by the main pulse could be affected, and effects of long rarefied plasmas on fast electron generation are investigated. It is found that the electron beam intensity becomes larger than that without the rarefied plasma, but the energy coupling rate from the heating laser to the core decreases due to lack of appropriate electrons for core heating. To achieve less than 10% degradation of the core electron temperature, the thin film must be expanded by irradiation of the pre-pulse so that the length and the density of rarefied plasmas become less than 500 ?m and one-tenth of the critical density. A thickness of the thin film can be determined by these criteria and the intensity of the pre-pulse
Complexity of the COVID-19 pandemic in Maringa
While extensive literature exists on the COVID-19 pandemic at regional and
national levels, understanding its dynamics and consequences at the city level
remains limited. This study investigates the pandemic in Maring\'a, a
medium-sized city in Brazil's South Region, using data obtained by actively
monitoring the disease from March 2020 to June 2022. Despite prompt and robust
interventions, COVID-19 cases increased exponentially during the early spread
of COVID-19, with a reproduction number lower than that observed during the
initial outbreak in Wuhan. Our research demonstrates the remarkable impact of
non-pharmaceutical interventions on both mobility and pandemic indicators,
particularly during the onset and the most severe phases of the emergency.
However, our results suggest that the city's measures were primarily reactive
rather than proactive. Maring\'a faced six waves of cases, with the third and
fourth waves being the deadliest, responsible for over two-thirds of all deaths
and overwhelming the local healthcare system. Excess mortality during this
period exceeded deaths attributed to COVID-19, indicating that the burdened
healthcare system may have contributed to increased mortality from other
causes. By the end of the fourth wave, nearly three-quarters of the city's
population had received two vaccine doses, significantly decreasing deaths
despite the surge caused by the Omicron variant. Finally, we compare these
findings with the national context and other similarly sized cities,
highlighting substantial heterogeneities in the spread and impact of the
disease.Comment: 20 pages, 5 figures, supplementary information; accepted for
publication in Scientific Report
- …