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Heat waves (HWs) are an extreme temperature condition that has a direct impact on human lives. In recent years, a large number ofpeople have died all over the world due to hot weather. The purpose of this study is to predict HWs accurately to mitigate the casualtiescaused by them. Two HW events are selected for this study (Event-1: 0000 UTC of 18 May to 0000 UTC of 25 May 2015, Event-2:0000 UTC of 05 April to 2100 UTC of 08 April 2015). At first, sensitivity tests have been done using different combinations ofphysics schemes. Sensitivity of Planetary boundary layer (PBL) and surface layer (SL) schemes combinations (YSU-Revised MM5,YSU-MM5, MYJ-Eta, and ACM2-Revised MM5) and land surface models (RUC, Noah, Noah-MP, and CLM4) are investigated topredict Comfort Index (CI), which is identified by using Physiological Equivalent Temperature (PET). To simulate PET, the primarymeteorological variables 2-m air temperature (T2), 2-m relative humidity (rh2), mean radiant temperature (TMRT), wind speed at 10m (ws10), and cloud cover data have been used. These parameters were simulated by the WRF model using both single and nesteddomains. The experiments found that the combination of the YSU-MM5 scheme and the Noah land surface model predicted theWRF simulated variables very well. The study also found that the CI exists between the slight heat stress to extreme heat stress andthe maximum PET values were found to be 47.6 ºC and 48.5 ºC for Rajshahi and Khulna event respectively. Dhaka Univ. J. Sci. 70(1): 70-78, 2022 (January)

Lightning discharge from thunderstorms is a major weather hazard and the loss of lives and properties caused by lightning is high in Bangladesh due to frequent lightning activity in the pre-monsoon season (March-May). In this study, numerical simulations in predicting the lightning flashes using diagnostic and explicit lightning parameterization options in WRF (Weather Research and Forecasting) model are performed over Bangladesh for three selected pre-monsoon lightning events (01 April 2019, 04 April 2019 and 20 May 2021). WRF model sensitivity for five microphysics and three planetary boundary layer schemes are also investigated in this work. The combination of Morrison and YSU (Yonsei University scheme)is found to be the best configuration by comparing the RMSE (Root Mean Square Error) of hourly area averaged rainfall. The lightning flash counts are estimated by using four diagnostic methods: (1) PR92 (Price and Rind 1992) (based on wmax), (2) PR92 (based on 20 dBZ top), (3) PR92 (based on level of neutral buoyancy), (4) LPI (Lightning Potential Index) based on cloud hydrometeors and updraft and (5) an explicit: physics-based method from cloud electrification referred to as WRF-Elec. The WWLLN (World Wide Lightning Location Network) and NASA LIS (Lightning Imaging Sensor) observations are used to compare the simulated lightning flashes for the three events. The 24 hr (hour) accumulated rainfall are also analyzed and the results show good consistency with the observations from NASA GPM datasets. Evaluations based on FSS (Fraction Skill Score) and performance diagrams are carried out for a better understanding of rainfall of how model simulations perform in forecasting rainfall. In qualitative assessment framework, the spatial patterns of WRF-Elec based simulations of lightning flashes to predict the primary regions of lightning occurrence exhibit good agreement with observations in most of the studied cases.

Background : Postoperative wound infection is a common consequence following laparotomy for peritonitis. Peptic ulcer perforation followed by peritonitis remains as an important cause of mortality. In severe peritonitis, the use of exploratory laparotomy and intra-operative lavage with large amount of saline solution has been the standard of care to reduce risk of postoperative infections. Objective: To compare the outcome between povidone iodine mixed normal saline (N/S) lavage and conventional normal saline lavage in the management of peritonitis in a tertiary care public hospital in Bangladesh. Methodology: This was a randomized clinical trial conducted in the department of Surgery, Shaheed Ziaur Rahman Medical College Hospital, Bogura during July 2013 to December 2013. There were total 50 patients, selected by purposive sampling as a diagnosed case of peritonitis due to peptic ulcer perforation. All the patients were divided into 2 groups by using coin toss as group A (conventional N/S) and group B (povidone iodine mixed with N/S). The data were collected using the pretested data collection sheet. Results were tested by chi-square test to see their level of significance with a p-value at <0.05. Results: The maximum (17, 34.0%) patients presented as peritonitis due to peptic ulcer perforation was from 18-30 years age group. The mean age of the patient was 29.16±9.25 years (age range: 18-61 years). The female to male ratio were 5.25:1 and 3.16:1 in group A and B respectively. Some (22, 44.0%) of the patients showed 13-18 hours delay since first symptom appeared. Fever (88.0% vs 80.0%), surgical site infection (SSI) (32.0% vs 24.0%), burst abdomen (20.0% vs 12.0%), intra-abdominal sepsis (8.0% vs 4.0%) were evident as postoperative complications in the groups A and B respectively. Only 1 (4.0%) patient died among group A patients due to sudden cardiac arrest. Mean hospital stay was a little lower among group B patients with milder complications and good outcome (though difference was not statistically significant). Conclusion: The outcome was observed better in case of using povidone iodine mixed with normal saline for peritoneal lavage. J Monno Med Coll June 2022;8(2): 36-39

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