Estimation of Secondary PM_2.5 in China and the United States using a Multi-Tracer Approach

PM2.5, generated via both direct emissions and secondary formations, can have varying environmental impacts due to different physical and chemical properties of its components. However, traditional methods to quantify different PM2.5 components are often based on online observations or lab analyses, which are generally high economic cost and labor-intensive. In this study, we develop a new method, named multi-tracer estimation algorithm (MTEA), to identify the primary and secondary components from routine observation of PM2.5. By comparing with the long-term and short-term measurements of aerosol chemical components in China, as well as aerosol composition network in the United States, MTEA is proved to be able to successfully capture the magnitude and variation of the primary PM2.5 (PPM) and secondary PM2.5 (SPM). Applying MTEA to China national air quality network, we find that 1) SPM accounts for 63.5 % of PM2.5 in southern cities of China averaged for 2014–2018, while in the North the proportion drops to 57.1 %, and at the same time the secondary proportion in regional background regions is ~19 % higher than that in populous regions; 2) the summertime secondary PM2.5 proportion presents a slight but consistent increasing trend (from 58.5 % to 59.2 %) in most populous cities, mainly because of the recent increase in O3 pollution in China; 3) the secondary PM2.5 proportion in Beijing significantly increases by 34 % during the COVID-19 lockdown, which might be the main reason of the observed unexpected PM pollution in this special period; and at least, 4) SPM and O3 show similar positive correlations in the BTH and YRD regions, but the correlations between total PM2.5 and O3 in these two regions are quite different as PPM levels determines. In general, MTEA is a promising tool for efficiently estimating PPM and SPM, and has huge potential for the future PM mitigation.

Solar Active Region Detection Using Deep Learning

Solar eruptive events could affect radio communication, global positioning systems, and some high-tech equipment in space. Active regions on the Sun are the main source regions of solar eruptive events. Therefore, the automatic detection of active regions is important not only for routine observation, but also for the solar activity forecast. At present, active regions are manually or automatically extracted by using traditional image processing techniques. Because active regions dynamically evolve, it is not easy to design a suitable feature extractor. In this paper, we first overview the commonly used methods for active region detection currently. Then, two representative object detection models, faster R-CNN and YOLO V3, are employed to learn the characteristics of active regions, and finally establish a deep learning–based detection model of active regions. The performance evaluation demonstrates that the high accuracy of active region detection is achieved by both the two models. In addition, YOLO V3 is 4% and 1% better than faster R-CNN in terms of true positive (TP) and true negative (TN) indexes, respectively; meanwhile, the former is eight times faster than the latter.

Retrospective evaluation of routine in-hospital observation in 433 patients after CT-guided biopsies

Background After computed tomography (CT)-guided interventions, routine in-hospital observation is recommended by the Cardiovascular and Interventional Radiological Society of Europe. Purpose To evaluate the frequency of delayed major complications or hospitalizations after CT-guided biopsies in patients with initially no or minor complications and to assess whether routine in-hospital observation is justified. Material and Methods This retrospective study included 433 outpatients after CT-guided biopsy of the thoracic (n = 176), abdominal (n = 129), or musculoskeletal (n = 128) region with subsequent in-hospital observation. Complications were graded according to the current Society of Interventional Radiology recommendations and grouped into minor or major. A complication that occurred during in-hospital observation was defined as delayed complication. A delayed major complication was a newly developed major complication or a progression from an initially minor to a major complication. Hospitalization frequencies were evaluated similarly. Occurrence, 95% confidence intervals (CI), and P values for significant differences between the three organ groups were calculated. If delayed major complications were more frequent than 1%, routine in-hospital observation was considered justified. Results Delayed, major complication frequencies were: thoracic, 8.2% (95% CI 4.6–13.4); abdominal, 0.0% (95% CI 0.0–2.9); and musculoskeletal, 0.0% (95% CI 0.0–2.9) ( P < 0.001). Delayed hospitalization frequencies were: thoracic, 8.8% (95% CI 5.0–14.2); abdominal, 1.6% (95% CI 0.2–5.6); and musculoskeletal, 0.0% (95% CI 0.0–2.9) ( P < 0.001). Conclusion After thoracic interventions, routine observation is considered justified for patient safety whereas routine observation may be omitted after musculoskeletal interventions. In the abdominal group, no delayed complications were observed, but delayed hospitalization occurred. Thus, in-hospital observation could be justified in a safe patient environment, but remains an individual decision.

Antifungal Activity of Centella asiatica on Radial Growth of Aspergillus species

The study was conducted to observe the antifungal activity of Centella asiatica against Aspergillus sp. Samples were collected from the local area of the Tangail district in Bangladesh. The bread was taken for isolating Aspergillus sp. in addition, Potato dextrose agar and malt extract agar were used as a media for culture and pure culture. One control group and two sample group (1%, 5%) hydrophilic extract of C. asiatica has been used. The routine observation was done for a total of 5 days after 24 hours. After routine observation, it has noticed that colony diameter and number of colonies increased rapidly from day 1 to day 5. The fungal growth was null of 5% solution both of PDA, MEA media at the first day and these increased with rising time on 5th days there were 1900 and 1600 respectively for black species and 1500 and 2500 respectively for green sp. Whereas compared with control group the growth was measured 1000, 1200 respectively at day 1 and these increased with rising time these numbers were 4000, 4200 respectively at day 5 for black. On the other hand, at 1st day the growth was measured 1100, 1200 respectively and these increased with rising time on 5th days there were 4200, 4300 respectively for green sp. However, at the end of the study, a remarkable change was observed between the control group and sample group after 1st, 2nd, 3rd, 4th and 5th days. Finally, the study showed that the bioactive compounds of C. asiatica are a potential source of preservative that inhibits the growth of fungus.

Prolonged Implantation of Sinus Devices and Implications for Chronic Rhinosinusitis: A Case Report and Review of the Literature

Background: Implantation of sinus stents and spacers can be used as adjuvant management to maintain patency of sinuses after endoscopic sinus surgery for chronic rhinosinusitis. These implants are typically removed several weeks after surgery. We present two cases of different patients who were initially treated by different physicians and were found to have retained sinus spacers in their paranasal sinuses 6-10 years after implantation. Case Presentation: Case 1: A 40-year-old male with chronic rhinosinusitis and history of balloon sinuplasty six years prior presented with worsening symptoms of chronic rhinosinusitis refractory to medical management. He underwent revision functional endoscopic sinus surgery and was found to have retained sinus implants in the left and right frontal sinus recesses. Case 2: A 48-year-old female with long-standing chronic rhinosinusitis refractory to medical management presented after two prior sinus surgeries most recently 10 years ago. She underwent revision functional endoscopic surgery and was found to have a retained sinus implant from prior surgery in the right frontal recess outflow tract embedded within scar tissue and reactive hyperostosis. Foreign bodies from both patients were removed without complication and patients were healing appropriately in the post-operative period. Conclusions: While sinus stents and spacers can help with post-operative scarring, leaving then unmonitored and in place will eventually result in them becoming a nidus for scarring and infection. It is critical that patients are aware of any foreign bodies we place, if they need scheduled removal or routine observation, and what symptoms may indicate that they are causing a problem.

Maser Theory: Old Problems and New Insights

Maser theory continues to be driven by advances in observational techniques. Here, I consider the responses to VLBI with space-Earth baselines and cross-correlation spectroscopy (a re-consideration of coherence properties), routine observation in full-Stokes polarization (a re-casting of the polarization transfer equations), and long-term variability monitoring (3-D modelling of irregular domains).