Low-Reynolds-number propeller systems have been widely used in aeronautical applications, such as unmanned aerial vehicles (UAV) and electric propulsion systems. However, the aerodynamic sound of the propeller systems is often significant and can lead to aircraft noise problems. Therefore, effective predictions of propeller noise are important for designing aircraft, and the different phases in aircraft design require specific prediction approaches. This paper aimed to perform a comparison study on numerical methods at different fidelity levels for predicting the aerodynamic noise of low-Reynolds-number propellers. The Ffowcs-Williams and Hawkings (FWH), Hanson, and Gutin methods were assessed as, respectively, high-, medium-, and low-fidelity noise models. And a coarse-grid large eddy simulation was performed to model the propeller aerodynamics and to inform the three noise models. A popular propeller configuration, which has been used in previous experimental and numerical studies on propeller noise, was employed. This configuration consisted of a two-bladed propeller mounted on a cylindrical nacelle. The propeller had a diameter of $D=9^{″}$ and a pitch-to-diameter ratio of $P/D=1$, and was operated in a forward-flight condition with a chord-based Reynolds number of $Re=4.8\times {10}^4$, a tip Mach number of $M=0.231$, and an advance ratio of $J=0.485$. The results were validated against existing experimental measurements. The propeller flow was characterized by significant tip vortices, weak separation over the leading edges of the blade suction sides, and small-scale vortical structures from the blade trailing edges. The far-field noise was characterized by tonal noise, as well as broadband noise. The mechanism of the noise generation and propagation were clarified. The capacities of the three noise modeling methods for predicting such propeller noise were evaluated and compared.

Rubus ellipticus is a perennial shrub occurring in natural vegetation of the temperate and subtropical Himalayas. For several years, plants of R. ellipticus in and around the Institute of Himalayan Bioresource Technology in Palampur were seen with mild mosaic and chlorotic symptoms on leaves followed by necrotic ring spots. Infected plants often recovered from the symptoms. The causal agent was mechanically transmissible to several herbaceous hosts including Cucumis sativus, Chenopodium album, C. quinoa, Cucurbita maxima, C. pepo, Melilotus alba, Trifolium repens, and Zinnia elegans. The virus incited chlorotic local lesions followed by systemic necrotic lesions or ring spots and severe stunting on C. sativus. Several aphid species (Myzus persicae, Aphis gossypii, A.fabae-solanella, Brevicoryne brassicae, and Macrosiphoniella sanbornii) were tried as viral vectors, but all failed to transmit the virus. Virus has been detected in pollen and fruit of infected plants. Ilarvirus-like particles, 27 nm in diameter, were observed in partially purified extracts of symptomatic plants of R. ellipticus and in experimentally infected C. sativus plants, but not in healthy plants. The isolate was distantly serologically related to apple mosaic virus and unrelated to tobacco streak virus. Presence of Prunus necrotic ring spot virus (PNRSV) in symptomatic plants was also confirmed by enzyme-linked immunosorbent assay with antiserum from American Type Culture Collection and Agdia, Inc. (Elkhart, IN). This is the first report of a viral disease in R. ellipticus. The presence of PNRSV in a new weed host may become an important constraint to production of susceptible agronomic crops around Palampur.

Objective This study aimed to investigate the burden of the COVID-19 pandemic on tuberculosis (TB) trends, patient demographics, disease types and hospitalisation duration within the Respiratory Medicine Department over three distinct phases: pre-COVID-19, COVID-19 and post-COVID-19. Design Retrospective analysis using electronic medical records of patients with TB admitted between June 2018 and June 2023 was done to explore the impact of COVID-19 on patients with TB. The study employed a meticulous segmentation into pre-COVID-19, COVID-19 and post-COVID-19 eras. Setting National Institute of Medical Science Hospital in Jaipur, Rajasthan, India. Primary and secondary outcome measures Primary outcome includes patients admitted to the Respiratory Medicine Department of the hospital and secondary outcome involves the duration of hospital stay. Results The study encompassed 1845 subjects across the three eras, revealing a reduction in TB incidence during the post-COVID-19 era compared with the pre-COVID-19 period (p<0.01). Substantial demographic shifts were observed, with 5.2% decline in TB incidence among males in the post-COVID-19 era (n=529) compared with the pre-COVID-19 era (n=606). Despite the decrease, overall TB incidence remained significantly higher in males (n=1460) than females (n=385), with consistently elevated rates in rural (65.8%) as compared with the urban areas (34.2%). Extended hospital stays were noted in the post-COVID-19 era compared with the pre-COVID-19 era (p<0.01). Conclusion The study underscores the influence of the COVID-19 pandemic on the TB landscape and hospitalisation dynamics. Notably, patient burden of TB declined during the COVID-19 era, with a decline in the post-COVID-19 era compared with the pre-COVID-19 era. Prolonged hospitalisation in the post-COVID-19 period indicates the need for adaptive healthcare strategies and the formulation of public health policies in a post-pandemic context. These findings contribute to a comprehensive understanding of the evolving TB scenario, emphasising the necessity for tailored healthcare approaches in the aftermath of a global health crisis.