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This research investigates the dynamics of higher-order nonlinear difference equations, specifically concentrating on seventh-order instances. Analytical solutions are obtained for particular equations, a formidable task owing to the absence of explicit mathematical techniques for their resolution. The qualitative characteristics of solutions, such as their stability, boundedness, and periodicity, are analysed by theoretical methods and numerical simulations. The results indicate that equilibrium points frequently lack local asymptotic stability, leading to intricate phenomena such as unbounded solutions and periodic attractors. These findings augment our understanding of nonlinear difference equations, offering significant implications for their use across various scientific fields. [ABSTRACT FROM AUTHOR]

This study aimed to compare the amount of fluoride uptake and the recharge and release characteristics of conventional glass ionomer cement (GIC) without any additives in comparison to conventional glass ionomer cement supplemented with silver nanoparticles (AgNPs) at two concentrations: 0.1% and 0.2% (w/w). A total of 60 specimens were used in this in vitro study. The sample was divided into six groups—including three groups without fluoride charge: Group 1 (conventional GIC), Group 2 (GIC with 0.1% silver nanoparticles), and Group 3 (GIC with 0.2% silver nanoparticles; and three groups with fluoride charge: Group 4 (conventional GIC with fluoride); Group 5 (GIC with 0.1% silver nanoparticles with fluoride); Group 6 (GIC with 0.2% silver nanoparticles with fluoride), where Group 1 is considered the control group and the other five groups are used as the test groups. The amount of fluoride released was measured on days 1, 2, 7, 15, and 30. The comparisons were made between the groups with and without fluoride and among all the groups. A significant difference in the amount of fluoride released was observed between the groups, with the highest amount occurring in Group 1, followed by Group 2; the lowest amount of fluoride released was observed in Group 3 (p < 0.05). The groups with fluoride recharge (Groups 4, 5, and 6) exhibited a higher amount of fluoride release than the groups with no recharge (Groups 1, 2, and 3); however, Group 1 has more fluoride release compared to all other groups on days 1, 2, 7, 15, and 30 (p < 0.05). The amount of released fluoride decreased from day 1 to day 30 in all of the groups in the study. Despite the antimicrobial and anticariogenic benefits of adding silver nanoparticles to GIC, it seems that fluoride release characteristics are significantly affected by the addition of this material. This may force the clinician to a compromise between the antimicrobial benefit of silver nanoparticles and the remineralizing advantage of fluoride. [ABSTRACT FROM AUTHOR]

In this paper, we explore the local dynamics, chaos, and bifurcations of a discrete Rosenzweig–Macarthur prey–predator model. More specifically, we explore local dynamical characteristics at equilibrium solutions of the discrete model. The existence of bifurcations at equilibrium solutions is also studied, and that at semitrivial and trivial equilibrium solutions, the model does not undergo flip bifurcation, but at positive equilibrium solutions, it undergoes flip and Neimark–Sacker bifurcations when parameters go through certain curves. Fold bifurcation does not exist at positive equilibrium, and we have studied these bifurcations by the center manifold theorem and bifurcation theory. We also studied chaos by the feedback control method. The theoretical results are confirmed numerically. [ABSTRACT FROM AUTHOR]

La 0.8 Ca 0.2 Mn 1- x Co x O 3 compounds with x = 0.0, 0.1, 0.2, and 0.3 were synthesized by sol–gel method and their structures characterized by Rietveld refinement of their powder x-ray diffraction patterns. The magnetocaloric effect of these compounds was investigated by means of specific heat measurements as a function of applied magnetic field. The zero-field specific-heat anomaly at the ferromagnetic-paramagnetic phase transition temperature broadened and reduced with increasing the Co content in the samples, resulting in broadening of the magnetocaloric parameter curves. The magnetic entropy change and the adiabatic temperature change were evaluated, and the observed behaviour was consistent with thermodynamic expectations. The change of the adiabatic temperature deduced from specific heat measurements were compared with those obtained from the indirect magnetization measurements method. Relatively high magnetic entropy change and adiabatic temperature change were observed, indicating that these compounds are potential magnetic refrigerants in the sub-room temperature regime. [ABSTRACT FROM AUTHOR]

Studies of the structural, magnetic and magnetocaloric properties of polycrystalline La0.8Ca0.2Mn1-xCoxO3 compounds (0 ≤ x ≤0.3) perovskite manganites were carried out. Samples were synthesized by sol–gel process and then heated at 1000°C for 3 h. X-ray powder diffraction and magnetic measurements were used to investigate the structural and magnetic properties. Rietveld analysis shows that the samples crystallize in the orthorhombic structure with Pnma space group. Crystallographic analysis shows a variation in lattice parameters as cobalt substitution increases, accompanied by a variation in the interatomic distances and a small increase in MT–O–MT angles (MT = cobalt and manganese). Magnetocaloric studies on La0.8Ca0.2Mn1-xCoxO3 compounds with x = 0 and x = 0.2 have been investigated by measuring the magnetization as a function of temperature. At 2 T, the maximum magnetic entropy⎢ΔSmaxM⎢ is about 3.09 J⋅Kg-1⋅K-1 and 1.123 J⋅Kg-1⋅K-1 for x = 0 and 0.2, respectively. Besides, the RCP value decreases with increasing Co content from 55.845 J⋅Kg-1 to 49.971 J⋅Kg-1. Also, the existence of Griffiths Phase and its influence in the phase transition is discussed. [ABSTRACT FROM AUTHOR]

Background: Hip fractures are defined as any fracture of the femur between the articular cartilages of the hip joint to 5 cm below the distal point of the lesser trochanter. Hip fracture is a worldwide public health problem that primarily affects osteoporotic individuals and the elderly. Up to 30 % of the elderly patients with a hip fracture die within the first year. Objective: to show the risk factors and post-operative complications of hip fracture in cases attending orthopedic department of Arar Central Hospital in Arar city. Methods: a cross sectional study conducted during the period from 1 December 2017 to 31 March 2018. A predesigned questionnaire was used for data collection, and included inquiries about sociodemographic data of the studied patients, performing muscular exercise, osteoporosis, diminished vision and disorders in equilibrium, causes of fracture, type and site of fracture, occurrence of complications of surgery, postoperative care and the final outcome of treatment. Results: Most (70.1%) of the studied population aged 22-59 years, males constituted 59.8%. Causes of hip fracture were accident in 66.7% and fall in 25.0%. Among hip fracture cases, 43.9% were obese, 13.1% have osteoporosis, and 17.8% have disorders in equilibrium. Males reported insignificant higher percentage of hip fracture than females (25.0% Vs. 18.6%). Osteoporosis, diminished vision, chronic diseases, continuous use of medications and smoking showed significant relation with hip fracture (P<0.05). While BMI, disorders in equilibrium and performing muscular exercise showed insignificant relation. Complications after surgery was osteomyelitis in 12.6%, early fixation failure in 4.2%, wound infections in 8.4% and hospital acquires pneumonia in 4.2%. Only two thirds of the cases were completely cured. Conclusion: in our study population in Arar city, males reported insignificant higher percentage of hip fracture than females. Osteoporosis, diminished vision, chronic illnesses, continuous use of medications and smoking were significant risk factors of hip fracture. Complications after surgery was included, osteomyelitis, early fixation failure, wound infections and hospital acquire pneumonia. Only two thirds of the cases were completely cured, the rest of cases showed disability and movement limitation. [ABSTRACT FROM AUTHOR]

Background: The increased incidence of cardiovascular disease between patients nowadays led to upsurge in the number of cardiac operations. After coronary artery bypass surgery, most patients remain free of symptoms for up to 15 years. The surgery also reduces the risk of heart attack and improves survival. Objective: to determine the predictors and outcome of coronary artery bypass surgery in patients attending the cardiac center in Arar, KSA all over the study period. Methods: The current study is a cross sectional study conducted during the period from September 2017 to March 2018. The current study included 72 individuals attending the cardiac center in Arar City. Collecting patients' data was conducted through interviewing the patients included in the study and reviewing their medical files. A predesigned questionnaire was used for data collection. Results: We found that 81.9% of cases were males, 61.1% aged from 30 to 39 years old, 34.4% of cases have a myocardial infraction as a clinical diagnosis before the operation, 25% had angina pain, and 50.0% were smokers. Hyperlipidemia, chronic kidney disease, and chronic obstructive lung disease were found in 59.7%, 83.3% and 77.8% respectively. There were 41.6% who had postoperative arrhythmia, 13.9% had bacterial infection in the site of operation and another 13.9% had hypotension, 11.1% re-operated due to bleeding, and 6.9% got postoperative acute myocardial infarction. After 6 month of the operation, 69.4% of cases were quite good while recurrence of chest pain found in12.5%, heart failure in 2.8% and 8.3% died. There was significant association between outcome of cases after 6 months of operation and patients age (P<0.05) and all the dead cases were males. Conclusion: Our findings indicated that, among cardiac patients attending the cardiac center in Arar, KSA, the preoperative characteristics are suggestive of 30 to 39 years old males with myocardial infraction, angina pain, smokers, have hyperlipidemia, chronic kidney disease, and chronic obstructive lung disease is undergoing coronary artery bypass surgery. The death rate was low and 69.4% of cases were quite good. [ABSTRACT FROM AUTHOR]