[Estimating the disease burden of seasonal influenza in China, 2006-2019].

Objective: To estimate the health impact and economic burden of seasonal influenza in mainland China. Methods: From systematic literature reviews, we collected the influenza-associated excess influenza-like-illness (ILI) outpatient consultation rates, hospitalization rates of severe acute respiratory infections (SARI) and respiratory excess mortality, 2006-2017. Using these data, as well as demographic data (2019), the number of influenza-associated excess ILI outpatient consultations, SARI hospitalizations and respiratory excess deaths were estimated. Then using per capita economic burden of influenza-associated outpatient consultations and hospitalizations, as well as the productivity loss of influenza-related premature deaths, the annual influenza-associated total economic burden was estimated. All costs were adjusted to 2019 using the consumer price index. Results: The annual influenza-associated excess ILI outpatient consultations, SARI hospitalizations and excess respiratory deaths were 3 million, 2.34 million, 0.09 million, respectively. The total economic burden was 26.38 billion CNY, accounting for 0.266‰ GDP in 2019, of which the hospitalization-related economic burden accounted for the highest proportion (86.4%, 22.79 billion CNY), followed by the outpatient-related economic burden (11.3%, 2.97 billion CNY), and the indirect economic burden of productivity loss of premature deaths was the lowest (2.4%, 0.62 billion CNY). Largest economic burden was observed in East China (10.51 billion CNY) and smallest observed in Northeast China (0.38 billion CNY). Conclusion: The health burden of influenza-related outpatient visits and hospitalizations were substantial. The economic burden of influenza-related SARI hospitalization was higher than that of influenza-related outpatients and pre-mature deaths. The highest economic burden of influenza occurred in the East China.

Towards high-energy, high-resolution computed tomography via a laser driven micro-spot gamma-ray source.

Computed Tomography (CT) is a powerful method for non-destructive testing (NDT) and metrology awakes with expanding application fields. To improve the spatial resolution of high energy CT, a micro-spot gamma-ray source based on bremsstrahlung from a laser wakefield accelerator was developed. A high energy CT using the source was performed, which shows that the resolution of reconstruction can reach 100 µm at 10% contrast. Our proof-of-principle demonstration indicates that laser driven micro-spot gamma-ray sources provide a prospective way to increase the spatial resolution and toward to high energy micro CT. Due to the advantage in spatial resolution, laser based high energy CT represents a large potential for many NDT applications.

Large-charge quasimonoenergetic electron beams produced by off-axis colliding laser pulses in underdense plasma.

Electrons can be efficiently injected into a plasma wave by colliding two counterpropagating laser pulses in a laser wakefield acceleration. However, the generation of a high-quality electron beam with a large charge is difficult in the traditional on-axis colliding scheme due to the growth of the electron beam duration coming from the increase of the beam charge. To solve this problem, we propose an off-axis colliding scheme, in which the collision point is away from the axis of the driver pulse. We show that the electrons injected from the off-axis region are highly concentered on the tail of the bubble even for a large trapped charge, thus feeling almost the same accelerating field. As a result, quasimonoenergetic electron beams with a large charge can be produced. The validity of this scheme is confirmed by both the particle-in-cell simulations and the Hamiltonian model. Furthermore, it is shown that a Laguerre-Gauss (LG) laser can be adopted as the injection pulse to realize the off-axis colliding injection in three dimensions symmetrically, which may be useful in simplifying the technical layout of the real experiment setup.

Note: Absolute calibration of two DRZ phosphor screens using ultrashort electron bunch.

This article gives the absolute calibration of two types phosphor screens (DRZ) that were used to detect and characterize electron bunches driven by laser-plasma accelerator. The test was performed with picoseconds electron bunch at a radio frequency linear electron accelerator in Tsinghua University. The photons emitted from DRZ screens showed good linear responses to the charge of incident electron bunch and cosine angular distribution in space. An energy conversional efficiency of effective scintillant matter was also calculated.