Local Stability of Equilibrium Points of a SIR Mathematical Model of Infectious Diseases

In this paper, we studied a SIR mathematical model of infectious diseases. We formulate a theorem on existence and uniqueness of solutions and establish the proof of the theorem We showed that the model has two equilibrium points: disease-free and endemic equilibrium. Local stability of the equilibrium points was obtained using reliable Jacobian matrices and basic reproduction number (R0). The analysis reveals that the disease- free equilibrium is locally asymptotically stable if R0 lt1, the infection is temporalwill disappear with time. On the other hand, if nbspR0 gt1, the number of infections rises, an epidemic results and the nbspendemic equilibrium is locally stable.nbspnbs

Determination of Hardness and Tensile Properties of Dissimilar Phase Structured Steel Weld

This work involves the use of submerged arc welding (SAW) technique in joining heat treated steel in alternate arrangement. The selected as-received steel was initially cut, machined and heat treated to develop a conventional microstructure prior to joining operation. All samples were subsequently characterized to investigate the effect of the process on the mechanical behaviors. 3360 Instron Universal Tensile testing machine was used for the tensile properties evaluation; Vickers’ microhardness testing machine was also used for the hardness evaluation at various zones. From the result, it was found that interchanging arrangement of the microstructures during welding yield better combined properties of the ultimate tensile strength, yield strength and with improvement in the strain-to-fracture of some of the samples. The adopted mechanism was also observed to yield better hardness property on the sample. This led to the recommendation of this technique to the oil and gas industry that need to transport their products via the giant water bodies to clients

Corrosion Behavior of Mild Steel in Different Concentrations of Ethanol Beverages

Corrosion behavior of mild steel was investigated in different blends of ethanol solution. Potentiodynamic polarization tests and weight loss analysis were carried out to study the corrosion polarization tendency of the various blends of the solution on mild steel using water as a control medium. Scanning electron microscope with energy-dispersive spectroscopy was employed to characterize the surface morphologies as well as the elemental composition of each material subjected to corrosion tests. The result of the potentiodynamic polarization curves showed that water contributed to the corrosion rate of the material. Further to this, ethanol samples behaved passive against corrosion degradation. The result of the weight loss indicated that corrosion of the mild steel actually took place. More so, the SEM/EDS revealed the microstructural behavior of the surface oxides, spots, cracks and corrosive pits at the interface with the ethanol environment. This study will help in improving the mechanical properties of mild steel material employed to produce spur gear that will reliably function in an ethanol environment

A new differential configuration suitable for realization of high CMRR, all-pass/notch filters

#yayıncısurumuyok# ; Tam metin hakemden geçmiş kopyadır.In this paper, a new configuration suitable for realization of differential input-differential output first order, second order all-pass and notch filters with high CMRR is given. The proposed configuration uses two negative type second-generation current conveyors (CCII-), and three admittances. Two first order and one second order all-pass filters and a notch filter (tunable if current controlled conveyor CCCII is used) are extracted from the proposed configuration. Tracking error, element mismatch, sensitivity analysis, simulation and experimental results are included

Surface Chemistry Studies of Emission and Thermal Behaviour of Developed Composites for Building Ceiling Materials

The emission of harmful elements from burning building ceiling materials and their attendant health effects on inhabitants within the vicinity of the emitted harmful elements is increasingly becoming a source of concern globally. Hence, the need to develop eco‐friendly flame‐retardant composite materials suitable for house ceiling purposes to forestall unwanted toxic emissions. This work identified the chemical structure of developed composite products and their emission performance during combustion. X‐ray Diffraction (XRD) analysis was used for phase quantification and E550 combustion gas analyzer for emission characterization of the developed composites. Thermolyne 950 °C oven was employed for the combustion analysis of the prepared composite at 500 °C. Quasi negligible SO2 and CO2 levels existed, while A4, 0.3Aldr0.23Cmt0.3Si0.05G0.12CS recorded maximum CO level, indicating toxic affluence. The low mass losses of all composite materials, especially for A2, 0.6Aldr0.34Cmt0.05G0.01OBSretard significantly due to its activities by the retardant constituent. The flame retardant nature of all produced composites was evidenced in their elemental composition. There was an absence of a flammable element and stable insulating compounds providing retardance to flame occurrences. These suppressions in flame inclination of the reinforced materials were noticed within the boundaries of the ceiling crystals from the structural examination. The intermetallic phase from the diffraction intensities showed the presence of a significant second bond interstitial solid‐phase across the matrix, especially for 0.6Aldr0.34Cmt0.05G0.01OBS ceiling material. This study has established the eco‐friendliness of developed building ceiling composite and the potential to reduce the importation of building ceilings. The developed ceiling composite evidently demonstrated high potential to compete favourably with imported ceiling materials in terms of fire resistance performance, low cost of production, and abundant availability of raw materials in the environment. Oil beanstalk is a novel material introduced as a reinforcement to developed building ceiling composite. This research provides a blueprint for manufacturers, construction and allied industry, and stakeholders in developing ecofriendly flame retardant composite ceilings whose materials can be readily sourced locally available in the environment

Genome-wide analysis of circulating cell-free DNA copy number detects active melanoma and predicts survival

BACKGROUND: A substantial number of melanoma patients develop local or metastatic recurrence, and early detection of these is vital to maximise benefit from new therapies such as inhibitors of BRAF and MEK, or immune checkpoints. This study explored the use of novel DNA copy-number profiles in circulating cell-free DNA (cfDNA) as a potential biomarker of active disease and survival. PATIENTS AND METHODS: Melanoma patients were recruited from oncology and dermatology clinics in Sheffield, UK, and cfDNA was isolated from stored blood plasma. Using low-coverage whole-genome sequencing, we created copy-number profiles from cfDNA from 83 melanoma patients, 44 of whom had active disease. We used scoring algorithms to summarize copy-number aberrations and investigated their utility in multivariable logistic and Cox regression analyses. RESULTS: The copy-number aberration score (CNAS) was a good discriminator of active disease (odds ratio, 3.1; 95% CI, 1.5–6.2; P = 0.002), and CNAS above or below the 75th percentile remained a significant discriminator in multivariable analysis for active disease (P = 0.019, with area under ROC curve of 0.90). Additionally, mortality was higher in those with CNASs above the 75th percentile than in those with lower scores (HR, 3.4; 95% CI, 1.5–7.9; P = 0.005), adjusting for stage of disease, disease status (active or resected), BRAF status, and cfDNA concentration. CONCLUSIONS: This study demonstrates the potential of a de novo approach utilizing copy-number profiling of cfDNA as a biomarker of active disease and survival in melanoma. Longitudinal analysis of copy-number profiles as an early marker of relapsed disease is warranted

Investigation of livestock for presence of Trypanosoma brucei gambiense in Tafa Local Government Area of Niger State, Nigeria

The study investigated the presence of Trypanosoma brucei gambiense in livestock to ascertain their reservoir role and also screened for other pathogenic trypanosomes of animals in Tafa Local Government Area of Niger state, Nigeria. A total of 460 livestock comprising (cattle, sheep, goats, and dogs) selected at random were bled, examined using the buffy coat and Giemsa stained thin film and packed cell volume estimated. Questionnaire was filled for each animal on demography, awareness and management practices. An overall prevalence of 2.17% with Trypanosoma brucei, T. congolense, T. vivax and a mixed infection of T. brucei and T. congolense observed microscopically awaiting characterization. Interviews revealed high awareness (82.8%) of tsetse and trypanosomiasis described as bush disease and abortion in four cows. The PCV values were within the normal range, however, a significant decrease (P<0.05) was observed in sheep aged 7months to 4years in two communities. Therefore, the study indicated the presence of T. brucei and other trypanosomes suggesting that animal trypanosomiasis is still a problem to animal health and wellbeing in the study area. The study recommends effective integrated chemotherapy and vector control including livestock rearing under intensive management system to boost livestock production and productivity

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Background: Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. // Methods: We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung's disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. // Findings: We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung's disease) from 264 hospitals (89 in high-income countries, 166 in middle-income countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in low-income countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. // Interpretation: Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between low-income, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030