A Sensitivity Study of Critical Flow Modeling with MELCOR 2.2 Code Based on the Marviken CFT-21 Experiment

The paper presents a study of the critical flow phenomena modeling with MELCOR 2.2.15254 severe accident computer code. The Marviken Critical Flow Test number 21 (CFT-21) experiment was selected as a representative critical flow-focused Separate Effect Test (SET). Various modeling aspects were investigated, including the nodalization, model setup, parameters, and sensitivity coefficients. A local-type sensitivity study was performed to analytically identify the significant parameters and assess their impact on the modeling. A dedicated regression-based approach, using standard deviation, was developed to find the best-fit MELCOR modeling parameters. The primary purpose of this work was to determine the appropriate approach to model critical flow with MELCOR 2.2, investigate the model performance, assess the influence of nodalization choices, identify significant sensitivity parameters, and prepare recommendations with an emphasis on best-estimate modeling. An additional outcome was the benchmark of the recent code version with the Marviken test.

SOCIALIZATION OF RADIOGRAPHER UNDERSTANDING OF DIAGNOSTIC REFERENCE LEVEL AS AN EFFORT TO OPTIMIZE RADIOGRAPHIC EXAMINATION

The use of X-rays cannot be separated from the radiation given to the patient's body, therefore the radiation exposure received by patients should be very low according to the ALARA principle (As Low As Reasonably Achieveable). The research method is a quantitative description by using themeasurement method radiation output as a reference for the estimated radiation dose received by the patient, then the analysis of the success of socialization to radiographers about DRL as an optimization effort in radiographic examination. The results of the radiation dose estimation using themethod radiation output by determining theequation power function of themeasurement radiation output where the value of the radiation dose rate increases as the kVp value increases with y= 0.0005x2.9242. From theresults, it was pre-test found that the number of correct answers was 120 and 84 wrong, with a percentage of 59% and the number of respondents 10.03 people. Meanwhile, for theresults, the post-test number of correct answers was 194 and 12 wrong, with a percentage of 94% and the number of respondents being 15.98 people. It is hoped that radiographers can apply the principle of optimization in carrying out all radiographic examinations.

Effect of Porosity on Soil-Water Retention Curves: Theoretical and Experimental Aspects

Porosity change is a common characteristic of natural soils in fluid-solid interaction problems, which can lead to an obvious change of the soil-water retention curve (SWRC). The influence of porosity on soil water retention phenomena is investigated by a theoretical model and an experimental test in this study. A model expressing the change in suction with porosity and effective saturation is put forward theoretically. The model is based on an idealization of three-phase porous materials, the pore structures of which are homogeneous and isotropic. It accounts for the porosity effect on soil water retention, using four parameters with clear physical meanings. The presented model can obtain the SWRC at any porosity, which will reduce the test number required in characterizing the hydraulic behavior of soil. A laboratory experiment for loamy sand with different porosities is performed. The test results show that suction has a significant variation with changes in porosity and decreases with the increase of porosity. The formulation is verified by both the test data and the literature data for FEBEX bentonite and Boom clay. The very good agreements between measured and predicted results show that the SWRC model is reliable and feasible for various soils.

A Multi-center Study of COVID-19 with Multivariate Prognostic Analysis

Coronavirus disease (COVID-19) pandemic is now a global health concern.However, there is no detailed analysis of the factors related to patients improvement.We compared the clinical characteristics, laboratory findings, CT images, and treatment of COVID-19 patients from two different cities in China. Onehundred and sixty-ninepatients were recruited from January 27 to March 17, 2020 at five hospitals in Hubei and Guangxi. Theywere divided into four groups according to age and into two groups according to presence ofcomorbidities. Multivariate statistical analyses were performed for the prognosis of the disease. Fifty-two patients (30.8%) had comorbidities, and the percentage of critical COVID-19was higher in the comorbidities group (11.6%vs.0.9%, p<0.05). Older patients had higher proportion of severe or critical disease.The resultsshowed that lymphocyte count was significantly associated with thenumber ofdays from positive COVID-19 nucleic acid testto negative test; number of days from onset of symptoms to confirmation of diagnosis was significantly associated with the time it took forsymptoms to improve; andnumber of days from onset of symptomsto confirmation of diagnosis and disease severity were significantly associated withchest computed tomography improvement. We concluded that age, comorbidities, lymphocyte count, and SpO2may predictthe risk of severity of COVID-19.Early isolation, early diagnosis, and early initiation of management canslow down the progression and spread ofCOVID-19.

Crash Testing and Evaluation of Culvert-Mounted Midwest Guardrail System

Concrete box culverts are usually installed under roadways to allow water drainage without affecting the motoring public. Culvert openings can represent a hazard on the roadside when they do not extend outside of the clear zone, and often require safety treatments in the form of roadside barriers. In this study, a modified design of Midwest Guardrail System (MGS) was evaluated for installation on a low-fill culvert with the strong-post attachment using through-bolts and epoxy anchorage through full-scale crash testing. The test installation consisted of MGS with a 31 in. top rail height, supported by W6 × 9 posts, spaced at 37½ in., attached to a low-fill culvert’s top slab with a 12 in. offset from the back of the post to the culvert headwall. Two crash tests were conducted according to the American Association of State Highway and Transportation Officials’ (AASHTO) Manual for Assessing Safety Hardware (MASH) 2016 Test Level 3 impact safety criteria. In test number CMGS-1, a 2,428-lb car impacted the MGS attached to the culvert at a speed of 61.3 mph and at an angle of 25.1°. In test number CMGS-2, a 5,013-lb pickup truck impacted the MGS attached to the culvert at a speed of 62.8 mph and an angle of 25.7°. In both tests, the vehicle was safely redirected and captured. Both tests were deemed acceptable according to TL-3 safety criteria in MASH. Recommendations were made for the safe installation of MGS atop low-fill culverts as well as transitions from the standard MGS to the culvert-mounted MGS.

Covid-19 mortality is associated with test number and government effectiveness

Objectives: A question central to the Covid-19 pandemic is why the Covid-19 mortality rate varies so greatly across countries. This study aims to investigate factors associated with cross-country variation in Covid-19 mortality.Methods: Covid-19 mortality rate was calculated as number of deaths per 100 Covid-19 cases. To identify factors associated with Covid-19 mortality rate, a multivariable linear regression model was applied to a cross-sectional dataset comprising 78 countries and 1,790,550 patients infected by Covid-19. We retrieved data from the Worldometer website and the Worldwide Governance Indicators and World Development Indicators databases.Results: Covid-19 mortality rate was negatively associated with Covid-19 test number per 1,000 population (RR=0.97; 95% CI 0.96 to 0.99, P=0.013) and government effectiveness indicator (RR=0.96; 95% CI 0.93 to 0.98, P=0.001). Covid-19 mortality rate was positively associated with number of critical cases per 100 Covid-19 cases, Covid-19 case number per 10,000 population, proportion of population aged 65 or older and proportion of deaths attributable to communicable diseases in previous years (all with P<0.05). Predicted mortality rates were highly associated with observed mortality rates (r = 0.74; P<0.001).Conclusions: Multiple factors were associated with Covid-19 mortality rates. Increasing Covid-19 testing and improving government effectiveness may have the potential to attenuate Covid-19 mortality.Authors Li-Lin Liang and Chun-Ying Wu contributed equally to this work.

Persistent viral shedding of SARS-CoV-2 in faeces - a rapid review

AimIn addition to respiratory symptoms, COVID-19 can present with gastrointestinal complaints suggesting possible faeco-oral transmission. The primary aim of this review was to establish the incidence and timing of positive faecal samples for SARS-CoV-2 in patients with COVID-19.MethodsA systematic literature review identified studies describing COVID-19 patients tested for faecal virus. Search terms for Medline included ‘clinical’, ‘faeces’, ‘gastrointestinal secretions’, ‘stool’, ‘COVID-19’, ‘SARS-CoV-2’ and ‘2019-nCoV’. Additional searches were done in AJG, Gastroenterology, Gut, Lancet Gastroenterology and Hepatology, The WHO Database, CEBM, NEJM, social media and the NICE, bioRxiv and medRxiv preprints. Data were extracted concerning the type of test, number and timing of positive samples, incidence of positive faecal tests after negative nasopharyngeal swabs and evidence of viable faecal virus or faeco-oral transmission of the virus.ResultsThere were 26 relevant articles identified. Combining study results demonstrated that 53·9% of those tested for faecal RNA were positive. Duration of faecal viral shedding ranged from 1 to 33 days after a negative nasopharyngeal swab with one result remaining positive 47 days after onset of symptoms. There is insufficient evidence to suggest that COVID-19 is transmitted via faecally shed virus.ConclusionThere is a high rate of positive PCR tests with persistence of SARS-CoV-2 in faecal samples of patients with COVID-19. Further research is needed to confirm if this virus is viable and the degree of transmission through the faeco-oral route. This may have important implications on isolation, recommended precautions and protective equipment for interventional procedures involving the gastrointestinal tract.

The experience of using the UltraFertile Plus micronutrient complex for correction of idiopathic forms of secretory infertility in men

The study objective is to evaluate the effect of the UltraFertile Plus micronutrient complex on parameters of the ejaculate in men with idiopathic infertility.Materials and methods. The study included 45 men aged between 24 and 48 years (median 31 years) suffering infertility in marriage. All patients took 2 capsules of UltraFertile Plus once a day in the morning at breakfast for 3 months. The patients didn’t receive any other therapy during the study. Hormonal status, spermogram parameters, MAR test, number of sperm with fragmented DNA using flow cytofluorometry with monoclonal antibodies were analyzed prior to treatment and after it.Results. After a course of UltraFertile Plus therapy, significant improvement of spermogram parameters was observed in the majority of patients. Sperm count increased from 43.5 to 62.0 million/ml (p < 0.001), percent of progressive motile sperm (categories А and В) increased from 29.3 to 44.4 % (p <0.001), normal morphology sperm count increased from 3.0 to 4.0 % (p <0.001). Administration of UltraFertile Plus promoted a decrease in the number of sperm with fragmented DNA from 14.7 to 10.1 % (p = 0.001) and was effective for patients with this parameter below 22 %. No significant effect of UltraFertile Plus was observed in MAR test. Plasma total and free testosterone levels significantly increased as a result of administration of UltraFertile Plus.Conclusion. Administration of the UltraFertile Plus micronutrient complex promotes a decrease in sperm DNA fragmentation, an increase in sperm count, percentage of progressive motile sperm and normal morphology sperm, testosterone level.The authors declare no conflict of interest.All patients gave written informed consent to participate in the study.