Heat transfer in a channel with inclined target surface cooled by single array of centered impinging jets

An experimental investigation has been carried out to study the heat transfer characteristics in a channel with heated target plate inclined at an angle cooled by single array of equally spaced centered impinging jets for three different jet Reynolds numbers (Re=9300, 14400 and 18800). Air ejected from an array of orifices impinges on the heated target surface The target plate forms the leading edge of a gas turbine blade cooled by jet impingement technique. The work includes the effect of jet Reynolds numbers and feed channel aspect ratios (H/d = 5, 7, 9 where H=2.5, 3.5, 4.5 cm and d=0.5 cm) on the heat transfer characteristics for a given orifice jet plate configuration with equally spaced centered holes with outflow exiting in both directions (with inclined heated target surface). In general, It has been observed that, H/d=9 gives the maximum heat transfer over the entire length of the target surface as compared to all feed channel aspect ratios. H/d=9 gives 3% more heat transfer from the target surface as compared to H/d=5 (for Re=14400). Also, it has been observed that the magnitude of the averaged local Nusselt number increases with an increase in the jet Reynolds number for all the feed channel aspect ratios studied

Selenium, Selenoproteins, and Heart Failure:Current Knowledge and Future Perspective

PURPOSE OF REVIEW: (Mal-)nutrition of micronutrients, like selenium, has great impact on the human heart and improper micronutrient intake was observed in 30–50% of patients with heart failure. Low selenium levels have been reported in Europe and Asia and thought to be causal for Keshan disease. Selenium is an essential micronutrient that is needed for enzymatic activity of the 25 so-called selenoproteins, which have a broad range of activities. In this review, we aim to summarize the current evidence about selenium in heart failure and to provide insights about the potential mechanisms that can be modulated by selenoproteins. RECENT FINDINGS: Suboptimal selenium levels (<100 μg/L) are prevalent in more than 70% of patients with heart failure and were associated with lower exercise capacity, lower quality of life, and worse prognosis. Small clinical trials assessing selenium supplementation in patients with HF showed improvement of clinical symptoms (NYHA class), left ventricular ejection fraction, and lipid profile, while governmental interventional programs in endemic areas have significantly decreased the incidence of Keshan disease. In addition, several selenoproteins are found impaired in suboptimal selenium conditions, potentially aggravating underlying mechanisms like oxidative stress, inflammation, and thyroid hormone insufficiency. SUMMARY: While the current evidence is not sufficient to advocate selenium supplementation in patients with heart failure, there is a clear need for high level evidence to show whether treatment with selenium has a place in the contemporary treatment of patients with HF to improve meaningful clinical endpoints. GRAPHICAL ABSTRACT: [Figure: see text

FACULTY MEMBERS’ VIEWS OF EFFECTIVE TEACHING: A CASE STUDY OF QATAR UNIVERSITY

Effective teaching (ET) has recently drawn attention within higher educational intuitions owing to the need for greater accountability, and high quality learning outcomes.  The present study investigated Qatar University faculty member’s (QUFM) perception of ET, characteristics, practices, and impediment, by assembling data from a cluster sample of 75, using a quantitative approach. The methodology that was utilized took the form of five research questions were answered using a basic descriptive and inferential statistical approach. Results indicate that; 52% of QUFM consider the ET term is ambiguous that means 48% of QUFM population are not contributing in fulfilling the adapted strategy of education and learning excellency, which is based on achieving ET. Moreover, the data revealed that 57.14% of QUFM’s instructional knowledge is not at the acceptable rate. Finally, the results suggested that further training in implementing ET concepts is required for most academic staff.  Article visualizations

High selenium levels associate with reduced risk of mortality and new onset heart failure:data from PREVEND

AIM: To elucidate the relationship between serum selenium levels and the risk of mortality and new onset heart failure in the general adult population. METHODS AND RESULTS: Selenium was measured in a Dutch cohort and a retrospective analysis of prospectively assessed data was performed. Main outcome measures were all-cause mortality and incidence of new-onset heart failure (HF) separately, and combined as a composite endpoint. Serum selenium was measured in 5973 subjects and mean selenium concentration was 84.6 (±19.5) μg/L. Mean age was 53.6 (±12.1) years and 3103 subjects (52%) were females. Median follow-up period was 8.4 years. Selenium levels associated positively with female sex, higher total cholesterol and glucose concentrations, and associated negatively with incidence of anemia, iron deficiency, current smoking, increasing C-reactive protein levels, and higher body mass index. Univariate analysis on all subjects showed no association of continuous selenium concentrations, per 10 μg/L increase, with the composite endpoint (Hazard Ratio [HR]=0.96, 95% Confidence interval [CI]: 0.87 to 1.06, p = 0.407). However, significant interaction with smoking status was observed. In non-smoking subjects (N=4288), continuous selenium concentrations were independently associated with reduced mortality risk (HR=0.87, 95% CI: 0.79 to 0.96, p = 0.005), lower risk of new-onset HF (HR=0.82, 95% CI: 0.69 to 0.96, p = 0.017), as well as reduced risk of the composite endpoint (HR= 0.86, 95% CI: 0.79 to 0.94, p = 0.001). In smoking subjects, no associations were found. CONCLUSION: Serum selenium was independently associated with multiple indicators of the metabolic syndrome. In addition, high selenium levels were independently associated with reduced mortality and new-onset HF in non-smokers. Well-powered interventional studies are necessary to evaluate the potential benefit of repleting selenium, especially in non-smoking subjects

A Clinical Tool to Predict Low Serum Selenium in Patients with Worsening Heart Failure

Selenium is an essential micronutrient, and a low selenium concentration (&lt;100 µg/L) is associated with a poorer quality of life and exercise capacity, and an impaired prognosis in patients with worsening heart failure. Measuring selenium concentrations routinely is laborious and costly, and although its clinical utility is yet to be proven, an easy implemented model to predict selenium status is desirable. A stepwise multivariable logistic regression analysis was performed using routinely measured clinical factors. Low selenium was independently predicted by: older age, lower serum albumin, higher N-terminal pro-B-type natriuretic peptide levels, worse kidney function, and the presence of orthopnea and iron deficiency. A 10-points risk-model was developed, and a score of ≥6 points identified &gt;80% of patients with low selenium (sensitivity of 44%, specificity of 80%). Given that selenium and iron overlap in their physiological roles, we evaluated the shared determinants and prognostic associates. Both deficiencies shared similar clinical characteristics, including the model risk factors and, in addition, a low protein intake and high levels of C-reactive protein. Low selenium was associated with a similar or worse prognosis compared to iron deficiency. In conclusion, although it is difficult to exclude low selenium based on clinical characteristics alone, we provide a prediction tool which identifies heart failure patients at higher risk of having a low selenium status.</p

Fuzzy Logic Based Self-Adaptive Handover Algorithm for MobileWiMAX.

It is well known that WiMAX is a broadband technology that is capable of delivering triple play (voice, data, and video) services. However, mobility in WiMAX system is still a main issue when the mobile station (MS) moves across the base station (BS) coverage and be handed over between BSs. Among the challenging issues in mobile WiMAX handover are unnecessary handover, handover failure and handover delay, which may affect real-time applications. The conventional handover decision algorithm in mobile WiMAX is based on a single criterion, which usually uses the received signal strength indicator (RSSI) as an indicator, with the other fixed handover parameters such as handover threshold and handover margin. In this paper, a fuzzy logic based self-adaptive handover (FuzSAHO) algorithm is introduced. The proposed algorithm is derived from the self-adaptive handover parameters to overcome the mobile WiMAX ping-pong handover and handover delay issues. Hence, the proposed FuzSAHO is initiated to check whether a handover is necessary or not which depends on its fuzzy logic stage. The proposed FuzSAHO algorithm will first self-adapt the handover parameters based on a set of multiple criteria, which includes the RSSI and MS velocity. Then the handover decision will be executed according to the handover parameter values. Simulation results show that the proposed FuzSAHO algorithm reduces the number of ping-pong handover and its delay. When compared with RSSI based handover algorithm and mobility improved handover (MIHO) algorithm, respectively, FuzSAHO reduces the number of handovers by 12.5 and 7.5 %, respectively, when the MS velocity is <17 m/s. In term of handover delay, the proposed FuzSAHO algorithm shows an improvement of 27.8 and 8 % as compared to both conventional and MIHO algorithms, respectively. Thus, the proposed multi-criteria with fuzzy logic based self-adaptive handover algorithm called FuzSAHO, outperforms both conventional and MIHO handover algorithms

Micronutrient deficiencies and new-onset atrial fibrillation in a community-based cohort:data from PREVEND

Aim: Malnutrition has been linked to cardiovascular diseases. Both selenium and iron deficiency have been associated with worse prognosis in patients with heart failure (HF). Yet, little is known about the role of micronutrients in the development of atrial fibrillation (AFib). In this study, we aimed to elucidate the association of micronutrient deficiencies with new-onset AFib. Methods: Selenium, magnesium, and iron parameters were measured in a well-characterized prospective cohort study (N = 5452). Selenium deficiency was defined as serum selenium &lt; 70 μg/L, iron deficiency as serum ferritin &lt; 30 μg/L, and magnesium deficiency as plasma magnesium &lt; 0.85 mmol/L. New-onset AFib was the primary outcome. Additionally, we tested for previously reported effect-modifiers where applicable. Results: Selenium, iron, and magnesium deficiency was observed in 1155 (21.2%), 797 (14.6%), and 3600 (66.0%) participants, respectively. During a mean follow-up of 6.2 years, 136 (2.5%) participants developed new-onset AFib. Smoking status significantly interacted with selenium deficiency on outcome (p = 0.079). After multivariable adjustment for components of the CHARGE-AF model, selenium deficiency was associated with new-onset AFib in non-smokers (HR 1.69, 95% CI 1.09–2.64, p = 0.020), but not in smokers (HR 0.78, 95% CI 0.29–2.08, p = 0.619). Magnesium deficiency (HR 1.40, 95% CI 0.93–2.10, p = 0.110) and iron deficiency (HR 0.62, 95% CI 0.25–1.54, p = 0.307) were not significantly associated with new-onset AFib. Conclusion: Selenium deficiency was associated with new-onset AFib in non-smoking participants. Interventional studies that investigate the effects of optimizing micronutrients status in a population at risk are needed to assess causality, especially in those with selenium deficiency. Graphical abstract: Micronutrients deficiencies (selenium, iron, and magnesium) have been associated with cardiovascular diseases and mitochondrial dysfunction in human cardiomyocytes. However, it is not known whether these deficiencies are associated with atrial fibrillation. To investigate this question, we measured all three micronutrients in 5452 apparently healthy individuals. After a mean follow-up of 6.2 years, there were 136 participants who developed atrial fibrillation. Participants with selenium deficiency had a significant increased risk to develop atrial fibrillation, as did the participants with two or more deficiencies. [Figure not available: see fulltext.]</p

The Importance of Preventive Medicine in Family Practice: A Review of Current Guidelines and Recommendations

Prevention is seen as a critical topic in family practice. Primordial prevention, primary prevention, secondary prevention, tertiary prevention, and quaternary prevention are all part of this strategy to disease prevention. To avoid the formation and development of risk factors, primary prevention focuses on addressing the fundamental causes and social determinants of disease. Primary prevention is the practice of preventing illnesses before they arise via the use of treatments such as immunizations and health education. Secondary prevention focuses on illness identification and intervention as early as possible to avoid disease development. Tertiary prevention addresses illness outcomes by restoring health and offering rehabilitation. Finally, quaternary prevention seeks to safeguard patients against needless medical treatments and the harm caused by over-medicating. Risks frequently rise in tandem with frailty and comorbidities. In contrast, advantages frequently drop as life expectancy increases. Preventive management strategies should consider the patient's viewpoint and be mutually agreed upon. Healthcare providers must prioritize the deployment of preventive care services, even when clinical treatments are required, in order to overcome preventive care hurdles. Healthcare practitioners may play a critical role in illness prevention and contribute to family well-being by investing in preventive care and executing these measures