30 research outputs found

    Theoretical Measuring for Negative Chromatic Dispersion Curves of Photonic Crystal Fiber by Gaussian Function

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    Negative dispersion curves in a typical type of high negative chromatic dispersion photonic crystal fiber(PCF) have been investigated in this paper. The depended class of (PCF) has double-core structure (core- region: which has inner core and outer core) with a honeycomb photonic lattice in the cladding region. Negative dispersion curves deviated from core-region of this type of fibers will be investigated. The investigation has depended an estimation process using an approximation function to create a mathematical model that enables us to measure negative dispersion curves. The influence of inner-core parameters (dcore d1 and d2) on dispersion curves has been investigated by varying the values of these parameters.  Negative dispersion curves that were introduced by a previous study using finite-difference frequency-domain (FDFD)method for this class of(PCFs) are directly included in this work in order  to measure matching ratio with our results.   Gaussian approximation function has been considered to estimate our mathematical model. Keywords: Photonic crystal fiber, Theoretical model, Negative chromatic dispersion, Gaussian function

    The effect of blade angles of the vertical axis wind turbine on the output performance.

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    There are many social, political and environmental issues associated with the use of fossil fuels. For this reason, there are numerous investigations currently being carried out to develop newer and renewable sources of energy to alleviate energy demand. Wind is one source of energy that can be harnessed using wind turbines. In this study, numerical investigations using CFD analysis have been carried out to determine the optimum dimensions of a wind turbine used in urban environments by varying the rotor and stator blade angles. The effect of these blade angles have been considered to be within the normal operating range (α from 1.689 to 21.689 , δ from 22.357 to 42.357 and γ from 18.2 to 38.2 ) while β was kept constant to 90 . The results show that as α increase torque output and power output increases to a certain point after which both these quantities start decreasing. On the contrary to α, as δ increase torque output and power output decreases. From the results it can be concluded that the ideal blade angles, for optimal power output, are α=16.689, γ=18.2 and δ=22.357

    Cytotoxicity of Nubein6.8 peptide isolated from the snake venom of Naja nubiae on melanoma and ovarian carcinoma cell lines

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    This study was conducted to examine the cytotoxic effects of Nubein6.8 isolated from the venom of the Egyptian Spitting Cobra Naja nubiae on melanoma (A375) and ovarian carcinoma cell lines and to reveal its mode of action. The size of Nubein6.8 (6801.8 Da) and its N-terminal sequence are similar to cytotoxins purified from the venom of other spitting cobras. Nubein6.8 showed a high significant cytotoxic effect on A375 cell line and moderate effect on A2780. A clonogenic assay showed that Nubein6.8 has a significant long-term potency on A375 cell survival when compared to A2780. The molecular intracellular signaling pathways of Nubein6.8 have been investigated using Western blotting analysis, flow cytometry, and microscale protein labeling. This data revealed that Nubein6.8 has DNA damaging effects and the ability to activate apoptosis in both tumor cell lines. Cellular uptake recordings revealed that the labeled-Nubein6.8 was intracellularly present in A375 cells while A2780 displayed resistance against it. SEM examination showed that Nubein6.8 was found to have high accessibility to malignant melanoma cells. The apoptotic effect of Nubein6.8 was confirmed by TEM examination that revealed many evident characteristics for Nubein6.8 apoptotic efficacy on A375 cell sections. Also, TEM reflected many resistant characteristics that faced Nubein6.8 acquisition through ovarian carcinoma cell sections. Accordingly, the snake venom peptide of Nubein6.8 is a promising template for developing potential cytotoxic agents targeting human melanoma and ovarian carcinoma

    Multicenter Randomized Controlled Crossover Trial Comparing Hemodynamic Optimization Against Echocardiographic Optimization of AV and VV Delay of Cardiac Resynchronization Therapy:The BRAVO Trial

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    Objectives: BRAVO (British Randomized Controlled Trial of AV and VV Optimization) is a multicenter, randomized, crossover, noninferiority trial comparing echocardiographic optimization of atrioventricular (AV) and interventricular delay with a noninvasive blood pressure method. Background: Cardiac resynchronization therapy including AV delay optimization confers clinical benefit, but the optimization requires time and expertise to perform. Methods: This study randomized patients to echocardiographic optimization or hemodynamic optimization using multiple-replicate beat-by-beat noninvasive blood pressure at baseline; after 6 months, participants were crossed over to the other optimization arm of the trial. The primary outcome was exercise capacity, quantified as peak exercise oxygen uptake. Secondary outcome measures were echocardiographic left ventricular (LV) remodeling, quality-of-life scores, and N-terminal pro–B-type natriuretic peptide. Results: A total of 401 patients were enrolled, the median age was 69 years, 78% of patients were men, and the New York Heart Association functional class was II in 84% and III in 16%. The primary endpoint, peak oxygen uptake, met the criterion for noninferiority (pnoninferiority = 0.0001), with no significant difference between the hemodynamically optimized arm and echocardiographically optimized arm of the trial (mean difference 0.1 ml/kg/min). Secondary endpoints for noninferiority were also met for symptoms (mean difference in Minnesota score 1; pnoninferiority = 0.002) and hormonal changes (mean change in N-terminal pro–B-type natriuretic peptide -10 pg/ml; pnoninferiority = 0.002). There was no significant difference in LV size (mean change in LV systolic dimension 1 mm; pnoninferiority < 0.001; LV diastolic dimension 0 mm; pnoninferiority <0.001). In 30% of patients the AV delay identified as optimal was more than 20 ms from the nominal setting of 120 ms. Conclusions: Optimization of cardiac resynchronization therapy devices by using noninvasive blood pressure is noninferior to echocardiographic optimization. Therefore, noninvasive hemodynamic optimization is an acceptable alternative that has the potential to be automated and thus more easily implemented. (British Randomized Controlled Trial of AV and VV Optimization [BRAVO]; NCT01258829

    The Changing Landscape for Stroke\ua0Prevention in AF: Findings From the GLORIA-AF Registry Phase 2

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    Background GLORIA-AF (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients with Atrial Fibrillation) is a prospective, global registry program describing antithrombotic treatment patterns in patients with newly diagnosed nonvalvular atrial fibrillation at risk of stroke. Phase 2 began when dabigatran, the first non\u2013vitamin K antagonist oral anticoagulant (NOAC), became available. Objectives This study sought to describe phase 2 baseline data and compare these with the pre-NOAC era collected during phase&nbsp;1. Methods During phase 2, 15,641 consenting patients were enrolled (November 2011 to December 2014); 15,092 were eligible. This pre-specified cross-sectional analysis describes eligible patients\u2019 baseline characteristics. Atrial fibrillation&nbsp;disease characteristics, medical outcomes, and concomitant diseases and medications were collected. Data were analyzed using descriptive statistics. Results Of the total patients, 45.5% were female; median age was 71 (interquartile range: 64, 78) years. Patients were from Europe (47.1%), North America (22.5%), Asia (20.3%), Latin America (6.0%), and the Middle East/Africa (4.0%). Most had high stroke risk (CHA2DS2-VASc [Congestive heart failure, Hypertension, Age&nbsp; 6575 years, Diabetes mellitus, previous Stroke, Vascular disease, Age 65 to 74 years, Sex category] score&nbsp; 652; 86.1%); 13.9% had moderate risk (CHA2DS2-VASc&nbsp;= 1). Overall, 79.9% received oral anticoagulants, of whom 47.6% received NOAC and 32.3% vitamin K antagonists (VKA); 12.1% received antiplatelet agents; 7.8% received no antithrombotic treatment. For comparison, the proportion of phase 1 patients (of N&nbsp;= 1,063 all eligible) prescribed VKA was 32.8%, acetylsalicylic acid 41.7%, and no therapy 20.2%. In Europe in phase 2, treatment with NOAC was more common than VKA (52.3% and 37.8%, respectively); 6.0% of patients received antiplatelet treatment; and 3.8% received no antithrombotic treatment. In North America, 52.1%, 26.2%, and 14.0% of patients received NOAC, VKA, and antiplatelet drugs, respectively; 7.5% received no antithrombotic treatment. NOAC use was less common in Asia (27.7%), where 27.5% of patients received VKA, 25.0% antiplatelet drugs, and 19.8% no antithrombotic treatment. Conclusions The baseline data from GLORIA-AF phase 2 demonstrate that in newly diagnosed nonvalvular atrial fibrillation patients, NOAC have been highly adopted into practice, becoming more frequently prescribed than VKA in&nbsp;Europe and North America. Worldwide, however, a large proportion of patients remain undertreated, particularly in&nbsp;Asia&nbsp;and North America. (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients With Atrial Fibrillation [GLORIA-AF]; NCT01468701

    Convalescent plasma in patients admitted to hospital with COVID-19 (RECOVERY): a randomised controlled, open-label, platform trial

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    SummaryBackground Azithromycin has been proposed as a treatment for COVID-19 on the basis of its immunomodulatoryactions. We aimed to evaluate the safety and efficacy of azithromycin in patients admitted to hospital with COVID-19.Methods In this randomised, controlled, open-label, adaptive platform trial (Randomised Evaluation of COVID-19Therapy [RECOVERY]), several possible treatments were compared with usual care in patients admitted to hospitalwith COVID-19 in the UK. The trial is underway at 176 hospitals in the UK. Eligible and consenting patients wererandomly allocated to either usual standard of care alone or usual standard of care plus azithromycin 500 mg once perday by mouth or intravenously for 10 days or until discharge (or allocation to one of the other RECOVERY treatmentgroups). Patients were assigned via web-based simple (unstratified) randomisation with allocation concealment andwere twice as likely to be randomly assigned to usual care than to any of the active treatment groups. Participants andlocal study staff were not masked to the allocated treatment, but all others involved in the trial were masked to theoutcome data during the trial. The primary outcome was 28-day all-cause mortality, assessed in the intention-to-treatpopulation. The trial is registered with ISRCTN, 50189673, and ClinicalTrials.gov, NCT04381936.Findings Between April 7 and Nov 27, 2020, of 16 442 patients enrolled in the RECOVERY trial, 9433 (57%) wereeligible and 7763 were included in the assessment of azithromycin. The mean age of these study participants was65·3 years (SD 15·7) and approximately a third were women (2944 [38%] of 7763). 2582 patients were randomlyallocated to receive azithromycin and 5181 patients were randomly allocated to usual care alone. Overall,561 (22%) patients allocated to azithromycin and 1162 (22%) patients allocated to usual care died within 28 days(rate ratio 0·97, 95% CI 0·87–1·07; p=0·50). No significant difference was seen in duration of hospital stay (median10 days [IQR 5 to >28] vs 11 days [5 to >28]) or the proportion of patients discharged from hospital alive within 28 days(rate ratio 1·04, 95% CI 0·98–1·10; p=0·19). Among those not on invasive mechanical ventilation at baseline, nosignificant difference was seen in the proportion meeting the composite endpoint of invasive mechanical ventilationor death (risk ratio 0·95, 95% CI 0·87–1·03; p=0·24).Interpretation In patients admitted to hospital with COVID-19, azithromycin did not improve survival or otherprespecified clinical outcomes. Azithromycin use in patients admitted to hospital with COVID-19 should be restrictedto patients in whom there is a clear antimicrobial indication

    Study of Daily Job Analysis of Primary, Intermidiate and Secondary Schools Principals in The Kingdom of Saudi Arabia.

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    The aim of the research: is to answer the following questions. I. What are the important works done by the principals of primary, intermediate and Secondary Schools? 2_ How do the School principals distribute their time to administrative works? 3. How much time do the principals prefer to spend in the domain of administrative and technical administrative work if they are provided with secretarial and clerical assistance? 4. How does the principal arrange his daily work in his school according to its importance? The correlation coefficient; was used for the analysis of the data: 1— 6, 1 112, N, N 2— 1, The correlation coefficient was then calculated between the actual tasks performed and the tasks principals would rather perform. Furthermore, the tasks performed were ordered according to their importance as viewed by principals_ The results of the research were as follows: 1. The principals in the primary intermediate and Secondary Schools spend a large. Percent of their time in the administrative works which reaches between 11.5%-13.7% from the total daily school works which have been limited in the research by ninteen works. 2. The correlation between the daily school works which occure and which they prefete are , 0.58, . This gives evidence that there are differences between what the principal is actualy doing and what he preferes to do. 3. This research resulted in the reexamination of the principals distribution of the daily works, 4. The research recommends the reevaluation of the selection of school principals in the view of these result

    Machine learning prediction models for battery-electric bus energy consumption in transit

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    The energy consumption (EC) of battery-electric buses (BEB) varies significantly due to the intertwined relationships of vehicular, operational, topological, and external parameters. This variation is posing several challenges to predict BEB’s energy consumption. Several studies are calling for the development of data-driven models to address this challenge. This study develops and compares seven data-driven modelling techniques that cover both machine learning and statistical models. The models are based on a full-factorial experimental design (n = 907,199) of a validated Simulink energy simulation model. The models are then used to predict EC using a testing dataset (n = 169,344). The results show some minor discrepancies between the developed models. All models explained more than 90% of the energy consumption variance. Further, the results indicate that road gradient and the battery state of charge are the most influential factors on EC, while driver behaviour and drag coefficient have the lowest impact
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