Discrete-time COVID-19 epidemic model with chaos, stability and bifurcation

In this paper, we explore local behavior at fixed points, chaos and bifurcations of a discrete COVID-19 epidemic model in the interior of R+5. It is explored that for all involved parametric values, COVID-19 model has boundary fixed point and also it has an interior fixed point under certain parametric condition(s). We have investigated local behavior at boundary and interior fixed points of COVID-19 model by linear stability theory. It is also explored the existence of possible bifurcations at respective fixed points, and proved that at boundary fixed point there exists no flip bifurcation but at interior fixed point it undergoes both flip and hopf bifurcations, and we have explored said bifurcations by explicit criterion. Moreover, chaos in COVID-19 model is also investigated by feedback control strategy. Finally, theoretical results are verified numerically

On Some Solvable Systems of Some Rational Difference Equations of Third Order

Our aim in this paper is to obtain formulas for solutions of rational difference equations such as xn+1=1±xn−1yn/1−yn,yn+1=1±yn−1xn/1−xn, and xn+1=1±xn−1yn−2/1−yn,yn+1=1±yn−1xn−2/1−xn, where the initial conditions x−2, x−1, x0, y−2, y−1, y0 are non-zero real numbers. In addition, we show that the some of these systems are periodic with different periods. We also verify our theoretical outcomes at the end with some numerical applications and draw it by using some mathematical programs to illustrate the results

Discrete-Time Predator-Prey Model with Bifurcations and Chaos

In this paper, local dynamics, bifurcations and chaos control in a discrete-time predator-prey model have been explored in ℝ+2. It is proved that the model has a trivial fixed point for all parametric values and the unique positive fixed point under definite parametric conditions. By the existing linear stability theory, we studied the topological classifications at fixed points. It is explored that at trivial fixed point model does not undergo the flip bifurcation, but flip bifurcation occurs at the unique positive fixed point, and no other bifurcations occur at this point. Numerical simulations are performed not only to demonstrate obtained theoretical results but also to tell the complex behaviors in orbits of period-4, period-6, period-8, period-12, period-17, and period-18. We have computed the Maximum Lyapunov exponents as well as fractal dimension numerically to demonstrate the appearance of chaotic behaviors in the considered model. Further feedback control method is employed to stabilize chaos existing in the model. Finally, existence of periodic points at fixed points for the model is also explored

PAX5α and PAX5β mRNA expression in breast Cancer: Relation to serum P53 and MMP2

Background: Many studies evaluated the role of paired box gene 5 (PAX5) in breast cancer. However, few investigated PAX5α and PAX5β isoforms individually. Objective: The aim of the present study is to evaluate mRNA expression of PAX5α and PAX5β in breast cancer and assessing their underlying pathological roles through investigating their correlations to matrix metalloproteinase2 (MMP2), p53 and cancer antigen 15-3 (CA15-3). Methods: Evaluation of PAX5α and PAX5β RNA expression in breast tissue samples was done by real-time PCR, serum MMP2 and p53 by ELISA and CA15-3 by chemiluminescent immunoassay in 55 infiltrating ductal carcinoma patients, 25 fibroadenoma patients and 15 control females who underwent plastic breast surgery. Results: PAX5α RNA was reduced while PAX5b RNA was elevated in breast cancer patients compared to other groups (p < 0.01). The best cutoff value of PAX5α was 61.15 with 78.2% sensitivity and 90% specificity and for PAX5β it was P2.01 with 83.6% sensitivity and 82.5% specificity. The RNA expression of PAX5β was higher in advanced grades and stages (p < 0.01), and significantly correlated to p53 (r: 0.51, p < 0.01), and CA15-3 (r: 0.45, p < 0.01). Moreover, PAX5α was negatively correlated to PAX5β (r: 0.42, p < 0.01), p53 (r: 0.53, p < 0.01) and MMP2 (r: 0.22, p < 0.05). Conclusions: The downregulation of PAX5α with upregulation of PAX5β RNA expressions could highlight the possible oncogenic role of PAX5 as a transcriptional factor in tumorigenesis and progression of breast cancer

Food Taste, Dietary Consumption, and Food Preference Perception of Changes Following Bariatric Surgery in the Saudi Population: A Cross-Sectional Study

Background: Bariatric surgery is known as the most effective treatment resulting in long-term weight loss for obesity. However, behavioral changes, including food preference, food allergies, and consumption, between groups of patients who underwent bariatric surgery in comparison with people who did not have bariatric surgery have not been fully discussed in the literature. Objective: The aim of this article is to describe patient-reported changes of perception related to food preferences, consumption, and food allergies in participants who underwent bariatric surgery and to compare their food consumption with participants who did not have bariatric surgery in Saudi Arabia. Methodology: This study is a secondary analysis of the Sharik Diet and Health National Survey (SDHNS) conducted in July 2021. Quota sampling was utilized to generate balanced distributions of participants by age and gender across all administrative regions of Saudi Arabia. Data collection included sociodemographic information (age, gender, and educational level), as well as food habits and the consumption of various food categories. Results: Of the 6267 potential participants contacted in 2021 from the 13 administrative regions of Saudi Arabia, 5228 successfully completed the interview, with a response rate of 83.4%. Gender was distributed equally among the total participants in the sample. The prevalence of bariatric surgeries in Saudi Arabia was estimated at around 4.1% of the total sample. More than 36% of people who had bariatric surgery experienced food taste changes, and around 15% reported a decrease in allergic reactions to food. Moreover, 68.1% had food preference changes, either starting to favor a new food or no longer favoring one. There was a significant association between consuming more red meat, chicken, and energy drinks and a decreased consumption of grains and rice among those who had the bariatric surgery compared with those who did not. Conclusions: This study found that more than two-thirds of people who had bariatric surgery self-reported food taste and food preference changes. More studies should be performed on the Saudi population, including clinical follow-up, to better understand these changes

On Free Vibrations of Elastodynamic Problem in Rotating Non-Homogeneous Orthotropic Hollow Sphere

The effect of non-homogenity and rotation on the free vibrations for elastodynamic problem of orthotropic hollow sphere is discussed. The free vibrations are studied on the basis of the linear elasticity. The determination is concerned with the eigenvalues of the natural frequency for mixed boundary conditions. The numerical results of the frequency equations are discussed in the presence and absence of non-homogenity and rotation. The computer simulated results indicate that the influence of non-homogenity and rotation in orthotropic material is pronounced

Malocclusion and craniofacial characteristics in Saudi adolescents with sickle cell disease

Background: Sickle cell disease can result in dentofacial abnormalities. However, in Saudi Arabia, there are limited data with respect to orthodontic manifestations in patients with sickle cell disease. Objective: To determine the malocclusion and craniofacial characteristics in sickle cell disease adolescents and compare them with that of controls from the Eastern Province of Saudi Arabia. Methods: This comparative cross-sectional study included 112 Saudi patients with sickle cell disease, aged 12–18 years, and 124 age-matched Saudi controls from three major hospitals in Al Khobar and Dammam, Saudi Arabia. The Dental Aesthetic Index was used to assess malocclusion and orthodontic treatment needs. Digital lateral cephalometric radiographs were recorded for each patient and control, and its analysis included linear and angular measurements. Results: The prevalence of malocclusion was 87.5% in sickle cell disease patients and 54% in controls (P = 0.0001). The percentage of sickle cell disease patients with severe malocclusion that required orthodontic treatment was higher than that of controls (37.5% vs. 26.6%). In the sickle cell disease cohort, incisal segment crowding (72.4%), overjet (67.3%) and maxillary misalignment in the anterior segment (56%) were the most prevalent types of malocclusions and were significantly higher than that of controls (P < 0.05). About 38% and 67% of the sickle cell disease patients had openbite and posterior crossbite, respectively, compared with 19.3% (P = 0.001) and 37.1% (P = 0.0001) of controls, respectively. Cephalometric analysis showed that SNA (86.7°) and ANB (9.9°) angles were significantly higher in sickle cell disease patients than in controls (81.5° and 2°, respectively). In addition, lower central incisor-to-Frankfort horizontal plane (55°) and interincisal angles (121.5°) were significantly lower in sickle cell disease patients than in controls. Conclusion: Adolescents with sickle cell disease had a higher prevalence of malocclusion and greater orthodontic treatment needs than controls. Similarly, they had greater incisal crowding, overjet, openbite and posterior crossbite and demonstrated higher SNA, ANB and lower interincisal angles than controls. The findings of this study suggest that adolescents with sickle cell disease should be provided frequent dental examinations and early orthodontic treatment to improve their oral health, and thus quality of life

Heuristic computational design of morlet wavelet neural network for solving the higher order singular nonlinear differential equations

The aim of this study is to present the numerical solutions of the higher order singular nonlinear differential equations using an advanced intelligent computational approach by manipulating the Morlet wavelet (MW) neural networks (NNs), global approach as genetic algorithm (GA) and quick local search approach as interior-point method (IPM), i.e., GA-IPM. MWNNs is applied to discretize the higher order singular nonlinear differential equations to express the activation function using the mean square error. The performance of the designed MWNNs using the GA-IPM is observed to solve three different variants based on the higher order singular nonlinear differential model to check the significance, efficacy and consistency of the designed MWNNs using the GAIPM. Furthermore, statistical performances are provided to check the precision, accuracy and convergence of the present approac

Non-operative treatment for simple acute appendicitis (NOTA) in children during the COVID-19 era: new lessons from the pandemic

Abstract Coronavirus (COVID-19) was a pandemic disease that was affecting our medical and surgical daily practice badly. The surgical management of acute appendicitis was the gold standard, but new studies suggest the safety of antibiotic treatment alone. Non-operative treatment for simple acute appendicitis (NOTA) avoids surgery, the risks of general anesthesia, and long hospital stays. It also decreases the risk of exposure to coronavirus. We aimed to study the cost-effectiveness and outcome of NOTA during the COVID-19 pandemic and compared it to single-incision pediatric endo-surgery appendectomy (SIPESA). A prospective cohort study for NOTA of patients from 6 to 12 years old in the COVID-19 pandemic period from April 1st, 2020, to April 30th, 2021, patients were divided into two groups: Group S was managed by SIPESA, and Group N was managed by NOTA. Family education and assurance with detailed explanation were done for early detection of any complications, and we continue monitoring the patients until their complete recovery. Group S had 24 cases (40%), mean age 9.3 years. Group N had 36 cases (60%), mean age 9.1 years. Six cases (17%) in group N were converted to surgical management in the first 6 months of the study. The mean cost dropped from $2736/day to$400/day. The mean psychological stress for the children improved from 4.4 in April to 2 in September. The mean follow-up was 3.5 months. NOTA is a feasible, cost-effective approach, and we recommend it, as we have learned this lesson during the COVID-19 pandemic days