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Asymptomatic transmission of the coronavirus disease and the infected individual prediction has become very important in the COVID-19 outbreak study. The asymptomatic and symptomatic transmission studies are still ongoing to assess their impacts on disease monitoring and burden. However, there has been limited research on how asymptomatic and symptomatic transmissions together can affect the coronavirus disease outbreak. A mathematical model is therefore needed to be developed in order to assess the effect of these transmissions on the coronavirus disease dynamics. This paper develops a mathematical model concerning asymptomatic and symptomatic disease transmission processes in the COVID-19 outbreak. The model sensitivity has been analysed in terms of the variance of each parameter, and the local stability at two equilibrium points have been discussed in terms of the basic reproduction number (R 0 ). It is found that the disease-free equilibrium gets stable for R 0 < 1 whereas the endemic equilibrium becomes stable for R 0 > 1 and unstable otherwise. The proportion of the effect of asymptomatic and symptomatic transmission rates on R0 is calculated to be approximately between 1 and 3. The results demonstrate that asymptomatic transmission has a significant impact compared to symptomatic transmission in the disease outbreak. Outcomes of this study will contribute to setting an effective control strategy for the COVID-19 outbreak.

Background: Exposure to inorganic arsenic (iAs) through drinking water is currently a serious threat to public health of millions of people worldwide including Bangladesh. Some recent studies have shown that telomere dysfunction is emerging as an important factor in the pathogenesis of different cardiovascular diseases. Arsenic plays significant role on telomere dysfunction by altering the expression of telomere-related genes. The study was aimed to investigate the effects of arsenic on hTERT mRNA levels and their combined role in increasing CVD susceptibility. Methods: In  this cross sectional study, total of 50 CVD patients who underwent open heart surgery were recruited for this study. Urine, nail and cardiac tissue samples were collected and analyzed for As. Blood samples were quantified for hTERT expression analysis using real-time polymerase chain reaction. Results: The hTERT mRNA expression was found approx. 10 fold higher in the As-exposed patients than the As-unexposed patients (p<0.01). A strong positive correlation (p<0.01, R>0.3) was found between the hTERT mRNA levels and As contents in the cardiac tissue, nail and urine samples of the study subjects. The significant increase (approx. 4 fold) in the hTERT mRNA expression was found in the patients with coronary artery disease (CAD) than the non-CAD patients. Conclusions: The results of the study suggest that arsenic exposure increases hTERT mRNA expression which may in turn modify As-induced cardiovascular outcomes. The findings of this study will help to look deep into the association of As exposure in cardiovascular disease pathogenesis to open a new window in the diagnosis and treatment procedure of CVD. Bangladesh Med Res Counc Bull 2019; 45: 03-10

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Quantum field theory can be understood through gauge theories. It is already established that the gauge theories can be studied either perturbatively or non-perturbatively. Perturbative means using Feynman diagrams and non-perturbative means using Path-integral method. Operator regularization (OR) is one of the exceptional methods to study gauge theories because of its twofold prescriptions. That means in OR two types of prescriptions have been introduced, which gives us the opportunity to check the result in self consistent way. In an earlier paper, we have evaluated basic QED loop diagrams in (3 + 1) dimensions using the both methods of OR and Dimensional regularization (DR). Then all three results have been compared. It is seen that the finite part of the result is almost same. In this paper, we are interested to evaluate the same basic loop diagrams in (2 + 1) space-time dimensions, because of two reasons: the main reason in (2 + 1) space-time dimensions, these loops diagrams are finite, on other hand, there are divergences in (3 + 1) space-time dimensions and the other reason is to see validity of using OR to evaluate Feynman loop diagrams in all dimensions. Here we have used both prescriptions of OR and DR to evaluate the basic loop diagrams and compared the results. Interestingly the results are almost same in all cases.