Multiplicity counting using organic scintillators to distinguish neutron sources: An advanced teaching laboratory

In this advanced instructional laboratory, students explore complex detection systems and nondestructive assay techniques used in the field of nuclear physics. After setting up and calibrating a neutron detection system, students carry out timing and energy deposition analyses of radiation signals. Through the timing of prompt fission neutron signals, multiplicity counting is used to carry out a special nuclear material (SNM) nondestructive assay. Our experimental setup is comprised of eight trans-stilbene organic scintillation detectors in a well-counter configuration, and measurements are taken on a spontaneous fission source as well as two ({\alpha},n) sources. By comparing each source's measured multiplicity distribution, the resulting measurements of the ({\alpha},n) sources can be distinguished from that of the spontaneous fission source. Such comparisons prevent the spoofing, i.e., intentional imitation, of a fission source by an ({\alpha},n) neutron source. This instructional laboratory is designed for nuclear engineering and physics students interested in organic scintillators, neutron sources, and nonproliferation radiation measurement techniques.Comment: 29 pages, 17 figures, pre-proof accepted to AJP, AJP number AJP22-AR-01524R2 (DOI: 10.1119/5.0139531

Original Article

Abstract Background: Mosquitoes transmit several diseases to human. There are several measures for control of larvae. As part of Integrated Vector Management (IVM) program, the utility of floating layers of polystyrene beads (EPS) is a potential alternative in habitats of mosquito larva. EPS beads prevent oviposition of mosquito as well as killing the immature stages by forming a tick layer on the water surface. They are cheap, environmentally safe and do not need frequent application and remain on the surface of water for long time. The objective of the current study was to asses the effectiveness of two types of polystyrene beads of (EPS) and (SWAP) for control of mosquito larvae under laboratory conditions. Methods: Anopheles stephensi and Culex quinquefasciatus were used for experimental purposes. In each tray 250 larvae of late 3 rd and early 4 th instars were introduced. The experiment was conducted on 4 replicates for An. stephensi, Cu. quinquefasciatus and combination of both. Emerging of adult mosquitoes were calculated every day until the end of experiments. Results: Mortality rate and Inhibition of Emerge (IE) for Cu. quinquefasciatus, An. stephensi and combination of both species was 97.8%, 100% and 99.07%, respectively using EPS. In average, EPS was able to kill 98.9% of larvae. The figures with SWAP were 63%, 91.05% and 72.65%, respectively. The average mortality for mosquitoes was 75.57% Conclusion: EPS and SWAP beads can be very effective and practical for elimination of An. stephensi and Cx. quinquefasciatus under the laboratory conditions

Call for emergency action to restore dietary diversity and protect global food systems in times of COVID-19 and beyond: Results from a cross-sectional study in 38 countries

Background: The COVID-19 pandemic has revealed the fragility of the global food system, sending shockwaves across countries\u27 societies and economy. This has presented formidable challenges to sustaining a healthy and resilient lifestyle. The objective of this study is to examine the food consumption patterns and assess diet diversity indicators, primarily focusing on the food consumption score (FCS), among households in 38 countries both before and during the first wave of the COVID-19 pandemic. Methods: A cross-sectional study with 37 207 participants (mean age: 36.70 ± 14.79, with 77 % women) was conducted in 38 countries through an online survey administered between April and June 2020. The study utilized a pre-tested food frequency questionnaire to explore food consumption patterns both before and during the COVID-19 periods. Additionally, the study computed Food Consumption Score (FCS) as a proxy indicator for assessing the dietary diversity of households. Findings: This quantification of global, regional and national dietary diversity across 38 countries showed an increment in the consumption of all food groups but a drop in the intake of vegetables and in the dietary diversity. The household\u27s food consumption scores indicating dietary diversity varied across regions. It decreased in the Middle East and North Africa (MENA) countries, including Lebanon (p \u3c 0.001) and increased in the Gulf Cooperation Council countries including Bahrain (p = 0.003), Egypt (p \u3c 0.001) and United Arab Emirates (p = 0.013). A decline in the household\u27s dietary diversity was observed in Australia (p \u3c 0.001), in South Africa including Uganda (p \u3c 0.001), in Europe including Belgium (p \u3c 0.001), Denmark (p = 0.002), Finland (p \u3c 0.001) and Netherland (p = 0.027) and in South America including Ecuador (p \u3c 0.001), Brazil (p \u3c 0.001), Mexico (p \u3c 0.0001) and Peru (p \u3c 0.001). Middle and older ages [OR = 1.2; 95 % CI = [1.125–1.426] [OR = 2.5; 95 % CI = [1.951–3.064], being a woman [OR = 1.2; 95 % CI = [1.117–1.367], having a high education (p \u3c 0.001), and showing amelioration in food-related behaviors [OR = 1.4; 95 % CI = [1.292–1.709] were all linked to having a higher dietary diversity. Conclusion: The minor to moderate changes in food consumption patterns observed across the 38 countries within relatively short time frames could become lasting, leading to a significant and prolonged reduction in dietary diversity, as demonstrated by our findings

Impact of COVID-19 lockdown on smoking (waterpipe and cigarette) and participants' BMI across various sociodemographic groups in Arab countries in the Mediterranean Region

INTRODUCTION: Tobacco smokers are at high risk of developing severe COVID-19. Lockdown was a chosen strategy to deal with the spread of infectious diseases; nonetheless, it influenced people's eating and smoking behaviors. The main objective of this study is to determine the impact of the COVID-19 lockdown on smoking (waterpipe and cigarette) behavior and its associations with sociodemographic characteristics and body mass index. METHODS: The data were derived from a large-scale retrospective cross-sectional study using a validated online international survey from 38 countries (n=37207) conducted between 17 April and 25 June 2020. The Eastern Mediterranean Region (WHO-EMR countries) data related to 10 Arabic countries that participated in this survey have been selected for analysis in this study. A total of 12433 participants were included in the analysis of this study, reporting their smoking behavior and their BMI before and during the COVID-19 lockdown. Descriptive and regression analyses were conducted to examine the association between smoking practices and the participant's country of origin, sociodemographic characteristics, and BMI (kg/m2). RESULTS: Overall, the prevalence rate of smoking decreased significantly during the lockdown from 29.8% to 23.5% (p<0.05). The percentage of females who smoke was higher than males among the studied population. The highest smoking prevalence was found in Lebanon (33.2%), and the lowest was in Oman (7.9%). In Egypt, Kuwait, Lebanon, and Saudi Arabia, the data showed a significant difference in the education level of smokers before and during the lockdown (p<0.05). Smokers in Lebanon had lower education levels than those in other countries, where the majority of smokers had a Bachelor's degree. The findings show that the BMI rates in Jordan, Lebanon, Oman, and Saudi Arabia significantly increased during the lockdown (p<0.05). The highest percentages of obesity among smokers before the lockdown were in Oman (33.3%), followed by Bahrain (28.4%) and Qatar (26.4%), whereas, during the lockdown, the percentage of obese smokers was highest in Bahrain (32.1%) followed by Qatar (31.3%) and Oman (25%). According to the logistic regression model, the odds ratio of smoking increased during the pandemic, whereas the odds ratio of TV watching decreased. This finding was statistically significant by age, gender, education level, country of residence, and work status. CONCLUSIONS: Although the overall rates of smoking among the studied countries decreased during the lockdown period, we cannot attribute this change in smoking behavior to the lockdown. Smoking cessation services need to anticipate that unexpected disruptions, such as pandemic lockdowns, may be associated with changes in daily tobacco consumption. Public health authorities should promote the adoption of healthy lifestyles to reduce the long-term negative effects of the lockdown

An Evaluation of the COVID-19 Pandemic and Perceived Social Distancing Policies in Relation to Planning, Selecting, and Preparing Healthy Meals: An Observational Study in 38 Countries Worldwide

Objectives: To examine changes in planning, selecting, and preparing healthy foods in relation to personal factors (time, money, stress) and social distancing policies during the COVID-19 crisis. Methods: Using cross-sectional online surveys collected in 38 countries worldwide in April-June 2020 (N = 37,207, Mage 36.7 SD 14.8, 77% women), we compared changes in food literacy behaviors to changes in personal factors and social distancing policies, using hierarchical multiple regression analyses controlling for sociodemographic variables. Results: Increases in planning (4.7 SD 1.3, 4.9 SD 1.3), selecting (3.6 SD 1.7, 3.7 SD 1.7), and preparing (4.6 SD 1.2, 4.7 SD 1.3) healthy foods were found for women and men, and positively related to perceived time availability and stay-at-home policies. Psychological distress was a barrier for women, and an enabler for men. Financial stress was a barrier and enabler depending on various sociodemographic variables (all p < 0.01). Conclusion: Stay-at-home policies and feelings of having more time during COVID-19 seem to have improved food literacy. Stress and other social distancing policies relate to food literacy in more complex ways, highlighting the necessity of a health equity lens. Copyright 2021 De Backer, Teunissen, Cuykx, Decorte, Pabian, Gerritsen, Matthys, Al Sabbah, Van Royen and the Corona Cooking Survey Study Group.This research was funded by the Research Foundation Flanders (G047518N) and Flanders Innovation and Entrepreneurship (HBC.2018.0397). These funding sources had no role in the design of the study, the analysis and interpretation of the data or the writing of, nor the decision to publish the manuscript.Scopu

Airflow assessment in a naturally ventilated greenhouse equipped with wind towers: numerical simulation and wind tunnel experiments

In this study, the air change rate and airflow distribution inside a greenhouse equipped with wind towers were analyzed using Computational Fluid Dynamics (CFD) simulations, considering different wind speeds (1–5 m/s) and incident angles (0–45°). The validation methods included smoke visualization, hot wire velocity point measurements, and Particle Image Velocimetry (PIV) measurements. The visualized and simulated flow regimes exhibited fair agreement. The average discrepancy between the hot wire velocity point measurements and simulated results was about 7.96%. The predicted vector fields in the inlet and outlet wind towers demonstrated good qualitative agreement with the corresponding PIV measurements. The discrepancy between the predicted and measured maximum air velocity in the inlet tower was 15%, while it was 3% in the outlet wind tower. At an external wind speed of 3 m/s and normal incidence angle, the average velocity of the airflow entering the greenhouse was 0.65 m/s (about one air change per minute), while the average air velocity in the greenhouse was 0.44 m/s. The average air velocity inside the greenhouse at a crop height (1 m) ranged from 0.3 to 1.8 m/s, which is within the optimum range of recommended air velocities for greenhouses.This work was supported by the Aspire Zone Foundation [award number: QUEX-CENG-ASPIRE-11/12-7].Scopu

Performance evaluation of a near-surface earth-to-air heat exchanger with short-grass ground cover: an experimental study

Given the negative environmental impact and high energy consumption of conventional air conditioning systems, the use of passive cooling systems has become particularly important. An earth-to-air heat exchanger, which utilizes the earth as a heat sink, is an efficient passive cooling system. Conventional earth-to-air heat exchangers are buried in the soil at a great depth, to ensure the soil temperature is relatively lower than the ambient air temperature during the hot season. Therefore, due to the great burial depth, their installation and maintenance are usually problematic. An alternative is a near-surface earth-to-air heat exchanger with short-grass ground cover. The grass cover reduces the near-surface soil temperature, eliminating the need to bury the earth-to-air heat exchanger at a great depth. In this study, the performance of a near-surface earth-to-air heat exchanger with short-grass ground cover was assessed experimentally. For an airflow rate of 607 m3/h, equivalent to 9.24 m/s, the inlet air temperature was reduced from 40.6 °C to about 34.1 °C, corresponding to a coefficient of performance of 13.4. The soil temperature 0.5 m away from the earth-to-air heat exchanger was not affected by its operation. On a typical summer day, compared to conventional air conditioning systems, about 76.5% less energy would be consumed by the earth-to-air heat exchanger to provide the same amount of cooling. Therefore, using this earth-to-air heat exchanger as a precooling system in combination with conventional air conditioning systems can both protect the environment and save energy.This work was supported by the Aspire Zone Foundation [award number QUEX-CENG-ASPIRE-11/12-7 ] and by a grant from the Qatar National Research Fund under its National Priorities Research Program [award number NPRP11S-0114-180295 ]. The contents of this work are solely the responsibility of the authors and do not necessarily represent the official views of the Qatar National Research Fund.Scopu

Comparison of 1D and 3D heat and mass transfer models of a counter flow dew point evaporative cooling system: Numerical and experimental studyÉtude comparative numérique et expérimentale de modèles de transfert de chaleur et de masse 1D et 3D d’un système de refroidissement évaporatif à point de rosée à contre-courant

In this study, the performance of a counter flow dew point evaporative cooling system has been examined, numerically and experimentally. A one-dimensional (1D) model of the heat and mass transfer in the cooling system is presented. In order to assess the 1D model, a detailed three-dimensional (3D) model is developed. Experimental results showed that the wet-bulb effectiveness of the cooling system could reach values as high as 125%. The predicted variations of air temperature along the channels of the cooling system by both models are in fair agreement. On average, the 1D model predicts lower outlet temperatures by about 1.86% relative to the 3D model. While the computational time of the 3D model is about three orders of magnitude higher than the 1D model. The predicted outlet temperature of the cooling system by the 1D and 3D models match the experimental results within 10% and 8.5%, respectively.This work was supported by Aspire Zone Foundation [award number QUEX-CENG-ASPIRE-11/12/7].Scopu

Evaluation of a novel greenhouse design for reduced cooling loads during the hot season in subtropical regions

Greenhouses provide an optimized growth environment for plants. However, providing this environment is energy intensive. In subtropical regions, most of this energy is to cater for the required cooling. The cooling demand is mainly attributed to the entry of excess solar radiation and heat gain through the greenhouse walls. This study proposes a thermally insulated greenhouse that allows the entry of optimum solar radiation levels through negative linear Fresnel lenses located in its roof. The lenses distribute the solar radiation over the plant rows. The performance of the proposed greenhouse in terms of providing the required levels of solar radiation for plant growth and the reduction in cooling load were assessed using ray tracing simulations and cooling load calculations. The results showed that the recommended optimum amount of solar radiation required for tomato growth can be achieved during the hot season inside the proposed greenhouse. In comparison to a conventional greenhouse, the monthly cooling load of the proposed greenhouse was about 80% less. Therefore, the proposed greenhouse can achieve the benefits of a closed greenhouse while overcoming the high cooling demand drawback, in subtropical regions.This work was supported by the Aspire Zone Foundation [award number QUEX-CENG-ASPIRE-11/12-7].Scopu

Regression models for performance prediction of counter flow dew point evaporative cooling systems

Practitioners take more interest in the output conditions of cooling systems than the details of the processes. In this study, regression models are developed that relate input parameters, including operational and geometrical parameters, to selected output responses of counter flow dew point evaporative cooling systems using numerical simulations and response surface methodology. The considered input operational parameters are inlet air temperature, inlet air relative humidity, inlet air velocity, and extraction ratio. The considered geometrical parameters are the channel length and channel width of the cooling system. The selected output responses are outlet air temperature, outlet air relative humidity, and wet-bulb effectiveness. The regression models are developed using a numerical model that is validated using experimental measurements. The predicted outlet temperatures of the counter flow dew point evaporative cooling system using the regression model match the numerical model predictions and experimental measurements within 4% and 10%, respectively. Therefore, the developed regression models provide a simple mean to predict the performance, aid in the design and optimization of counter flow dew point evaporative cooling systems.This work was supported by the Aspire Zone Foundation [award number QUEX-CENG-ASPIRE-11/12-7 ].Scopu