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1,564 result(s) for "Ahmed, Waleed A."
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Longevity of Middle East Respiratory Syndrome Coronavirus Antibody Responses in Humans, Saudi Arabia
Understanding the immune response to Middle East respiratory syndrome coronavirus (MERS-CoV) is crucial for disease prevention and vaccine development. We studied the antibody responses in 48 human MERS-CoV infection survivors who had variable disease severity in Saudi Arabia. MERS-CoV-specific neutralizing antibodies were detected for 6 years postinfection.
Indicators of Critical Illness and Predictors of Mortality in COVID-19 Patients
COVID-19 is an emerging disease all over the world and spreading at an unpredicted rate, resulting in significant influences on global economies and public health. Clinical, laboratory, and imaging characteristics have been partially described in some observational studies. Not enough systematic reviews on predictors of critical illness and mortality in COVID 19 have been published to date. In this review, we had illustrated the prognostic predictors of COVID-19 by gathering published information on the risk factors related to the outcomes of SARS-CoV-2 infections.
On the Analysis and Design of Fractional-Order Chebyshev Complex Filter
This paper introduces the concept of fractional-order complex Chebyshev filter. A fractional variation of Chebyshev differential equations is introduced based on Caputo fractional operator. The proposed equation is solved using fractional Taylor power series method. The condition for fractional polynomial solutions is obtained and the first four polynomials scaled using an appropriate scaling factor. The fractional-order complex Chebyshev low-pass filter based on the obtained fractional polynomials is developed. Two methods for obtaining the transfer functions of the complex filter are discussed. Circuit implementations are simulated using Advanced Design System (ADS) and compared with MATLAB numerical simulation of the obtained transfer functions to prove the validity of the two approaches.
Left Main Coronary Artery Revascularization in Patients with Impaired Renal Function: Percutaneous Coronary Intervention versus Coronary Artery Bypass Grafting
Abstract Introduction: The evidence about the optimal revascularization strategy in patients with left main coronary artery (LMCA) disease and impaired renal function is limited. Thus, we aimed to compare the outcomes of LMCA disease revascularization (percutaneous coronary intervention [PCI] vs. coronary artery bypass grafting [CABG]) in patients with and without impaired renal function. Methods: This retrospective cohort study included 2,138 patients recruited from 14 centers between 2015 and 2,019. We compared patients with impaired renal function who had PCI (n= 316) to those who had CABG (n = 121) and compared patients with normal renal function who had PCI (n = 906) to those who had CABG (n = 795). The study outcomes were in-hospital and follow-up major adverse cardiovascular and cerebrovascular events (MACCE). Results: Multivariable logistic regression analysis showed that the risk of in-hospital MACCE was significantly higher in CABG compared to PCI in patients with impaired renal function (odds ratio [OR]: 8.13 [95% CI: 4.19–15.76], p < 0.001) and normal renal function (OR: 2.59 [95% CI: 1.79–3.73]; p < 0.001). There were no differences in follow-up MACCE between CABG and PCI in patients with impaired renal function (HR: 1.14 [95% CI: 0.71–1.81], p = 0.585) and normal renal function (HR: 1.12 [0.90–1.39], p = 0.312). Conclusions: PCI could have an advantage over CABG in revascularization of LMCA disease in patients with impaired renal function regarding in-hospital MACCE. The follow-up MACCE was comparable between PCI and CABG in patients with impaired and normal renal function.
Clinical evaluation of a novel Mologic malaria Plasmodium falciparum LDH-dependent lateral flow rapid diagnostic test diagnostic accuracy: a cross-sectional study, Sudan
Background Malaria diagnosis by Rapid Diagnostic Test (RDT) is challenged by the newly emerging histidine-rich protein 2 (HRP2) gene deletion in the Plasmodium falciparum species. The alternative lactate dehydrogenase (LDH)-dependent RDTs suffer from low sensitivity, and improvement in the sensitivity of LDH RDTs is the cornerstone for detecting the (HRP2) gene deletion species. This study aimed to evaluate a novel, improved Mologic Malaria Pf LDH-dependent RDT for the diagnosis of P. falciparum malaria in partnership with the Foundation for Innovative Diagnostics (FIND), Switzerland. Methods This is a descriptive cross-sectional study evaluating the clinical performance of the improved Mologic LDH- RDT in two rural sites in Khartoum state, Sudan. Five hundred patients presenting with symptoms suggestive of malaria in the two primary care health centres were enrolled after signing informed consent. Finger-prick blood was collected for examination with microscopy, the index Mologic LDH RDT, the comparator RDT, and preparation of DBS for PCR, the reference method. Results The mean age of the study subjects was 31 years, ranging from 5 to 80 years. Out of 500 patients, 210 (42%) were positive by PCR, 200 (40%) by expert microscopy, 193 (38.6%) by index Mologic LDH RDT, and 199 (39.8%) by comparator RDT. The sensitivities of microscopy, index RDT, and comparator RDT were 95.24% (95% CI, 91.4–97.6), 91.9% (95% CI, 87.3–95.2), and 93.81% (95% CI, 89.6–96.6), respectively. All tests were nearly 100% specific for the detection of P. falciparum parasites. The concordance test showed almost perfect agreement with the reference test ( κ  = 0.929). Six samples were P. falciparum HRP2 Ag negative and were detected by Mologic LDH RDT. A limitation of this study is that there is no confirmation of HRP2 gene deletion by PCR. Conclusion The novel Mologic LDH RDT showed performance concordant with standard expert microscopy and the comparator HRP2-based RDT. The sensitivity of the Mologic LDH RDT makes it suitable for the clinical management of P. falciparum HRP2 negative malaria.
Morphology Transition Engineering of ZnO Nanorods to Nanoplatelets Grafted Mo8O23-MoO2 by Polyoxometalates: Mechanism and Possible Applicability to other Oxides
A new fundamental mechanism for reliable engineering of zinc oxide (ZnO) nanorods to nanoplatelets grafted Mo 8 O 23 -MoO 2 mixed oxide with controlled morphology, composition and precise understanding of the nanoscale reaction mechanism was developed. These hybrid nanomaterials are gaining interest due to their potential use for energy, catalysis, biomedical and other applications. As an introductory section, we demonstrate a new expansion for the concept ‘materials engineering’ by discussing the fabrication of metal oxides nanostructures by bottom-up approach and carbon nanoparticles by top-down approach. Moreover, we propose a detailed mechanism for the novel phenomenon that was experienced by ZnO nanorods when treated with phosphomolybdic acid (PMA) under ultra-sonication stimulus. This approach is expected to be the basis of a competitive fabrication approach to 2D hybrid nanostructures. We will also discuss a proposed mechanism for the catalytic deposition of Mo 8 O 23 -MoO 2 mixed oxide over ZnO nanoplatelets. A series of selection rules (SRs) which applied to ZnO to experience morphology transition and constitute theory for morphology transition engineering (TMTE) will be demonstrated through the article, besides a brief discussion about possibility of other oxides to obey this theory.
Effects of light spectrum on morpho-physiological traits of grafted tomato seedlings
It is already known that there are many factors responsible for the successful grafting process in plants, including light intensity. However, the influence of the spectrum of light-emitting diodes (LEDs) on this process has almost never been tested. During the pre-grafting process tomato seedlings grew for 30 days under 100 μmol m -2 s -1 of mixed LEDs (red 70%+ blue 30%). During the post-grafting period, seedlings grew for 20 days under the same light intensity but the lightening source was either red LED, mixed LEDs (red 70% + blue 30%), blue LED or white fluorescent lamps. This was done to determine which light source(s) could better improve seedling quality and increase grafting success. Our results showed that application of red and blue light mixture (R7:B3) caused significant increase in total leaf area, dry weight (total, shoot and root), total chlorophyll/carotenoid ratio, soluble protein and sugar content. Moreover, this light treatment maintained better photosynthetic performance i.e. more effective quantum yield of PSII photochemistry Y(II), better photochemical quenching (qP), and higher electron transport rate (ETR). This can be partially explained by the observed upregulation of gene expression levels of PsaA and PsbA and the parallel protein expression levels. This in turn could lead to better functioning of the photosynthetic apparatus of tomato seedlings and then to faster production of photoassimilate ready to be translocated to various tissues and organs, including those most in need, i.e., involved in the formation of the graft union.
Artificial neural networking for computational assessment of ternary hybrid nanofluid flow caused by a stretching sheet: implications of machine-learning approach
Researchers are mainly interested in using soft computing artificial intelligence (AI) methods due to their broad applications in analysis, modelling and simulations. Backpropagation neural networks, one of the supervised learning algorithms, is commonly used to train data networks by optimizing the error between actual and predicted values. To optimize this process of training data, Levenberg-Marquardt algorithm is applied; particularly beneficial for solving nonlinear fluid flow problems. Little knowledge is known about the ternary-hybrid nanofluid flow caused by a stretching surface with heat generation, viscous dissipation, magnetic effect and porosity etc. This article presents a novel machine-learning approach using backpropagation neural networks augmented with the Levenberg-Marquardt procedure to figure out the ternary-hybrid nanofluid flow generated by a stretching sheet. It uniquely examines the mixture of copper, Iron oxide and silicon dioxide nanoparticles inside a single base fluid within a magnetic field, tackling the research gaps in the effects of heat generation, viscous dissipation, porosity, and magnetic effects on fluid flow system and heat transfer. Shooting numerical technique (RK-5th) is used for solving the governing ordinary equations. Graphical illustration, error analysis, mean squared error, histograms and regression analysis justify the proposed method, showing better performance for ternary nanofluids.