81 research outputs found

    Gravity theory in SAP-geometry

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    The aim of the present paper is to construct a field theory in the context of absolute parallelism (Teleparallel) geometry under the assumption that the canonical connection is semi-symmetric. The field equations are formulated using a suitable Lagrangian first proposed by Mikhail and Wanas. The mathematical and physical consequences arising from the obtained field equations are investigated.Comment: 14 pages, References added and a reference updated, minor correction

    Experimental and computational investigation of energy ball wind turbine aerodynamic performance

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    The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This study was supported by the British University in Egypt and the Center for Renewable Energy. Author contributions E.E. prepared this manuscript. This study was carried out under the supervision of N.E., A.A.A.F., and T.A.E.-S. All authors carried out data analysis, discussed the results, and contributed to writing the paper.Peer reviewedPublisher PD

    Linear Connections and Curvature Tensors in the Geometry of Parallelizable Manifolds

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    In this paper we discuss curvature tensors in the context of Absolute Parallelism geometry. Different curvature tensors are expressed in a compact form in terms of the torsion tensor of the canonical connection. Using the Bianchi identities some other identities are derived from the expressions obtained. These identities, in turn, are used to reveal some of the properties satisfied by an intriguing fourth order tensor which we refer to as Wanas tensor. A further condition on the canonical connection is imposed, assuming it is semi-symmetric. The formulae thus obtained, together with other formulae (Ricci tensors and scalar curvatures of the different connections admitted by the space) are calculated under this additional assumption. Considering a specific form of the semi-symmetric connection causes all nonvanishing curvature tensors to coincide, up to a constant, with the Wanas tensor. Physical aspects of some of the geometric objects considered are mentioned.Comment: 16 pages LaTeX file, Changed title, Changed content, Added references, Physical features stresse

    A novel high CMRR trans-impedance instrumentation amplifier for biomedical applications

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    A compact high gain current mode instrumentation amplifier (IA) has been proposed for biomedical imaging applications. Conventional IAs rely on several matching resistors which occupies a lot of silicon area, the input and output common mode voltages are exactly same and the maximum applied signal amplitude is limited by internal node voltage swings. The present proposal eliminates the need for matching resistors by processing signals in the current mode. Hence input amplitudes are no longer limited by the voltage headroom and input and output common-mode voltages can be independent. An amplifier with a differential gain greater than 52dB and a common mode rejection ratio (CMRR) greater than 120dB has been implemented in 65nm CMOS Technology and Post layout simulations were presented. The total circuit occupies 4500um2 silicon area and circuit consumes ~260μA from 1.8V power supply

    MicroRNA expression analysis in endometriotic serum treated mesenchymal stem cells

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    Endometriosis is defined by presence of endometrial-like-tissue outside the uterus. Recently, ectopic endometriotic lesions have been suggested to originate by abnormal differentiation of endometrial mesenchymal stem cells (eMSCs). MicroRNAs (miRNAs) play an important role in the pathophysiology of endometriosis. Through a PCR array approach, we aimed to assess the differential expression of microRNAs in human eMSC treated in culture with sera derived from women with severe endometriosis. Sera were collected from five patients with severe endometriosis and three control women and added individually in the culture medium to conduct experimental and control eMSC sets, respectively. Regular microscopic follow-up for cell morphology was performed. SYBR Green based real-time PCR array was used to assess the expression of 84 miRNAs. Bioinformatics analysis was done to predict the target genes of the significantly dysregulated miRNAs and their enriched biological processes and pathways. Thirty-two miRNAs were found significantly dysregulated in experimental cultures. Functional enrichment analysis revealed several endometriosis associated biological processes and pathways were enriched by target genes of these miRNAs. In conclusion, treatment of human eMSCs with sera of severe endometriosis cases affects the expression of certain miRNAs and their target genes. This may result in altering cell functions and consequently, endometriosis development

    A low noise amplifier suitable for biomedical recording analog front-end in 65nm CMOS technology

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    This paper presents a fully integrated Front-end, low noise amplifier, dedicated to the processing of various types of bio-medical signals, such as Electrocardiogram (ECG), Electroencephalography (EEG), Axon Action Potential (AAP). A novel noise reduction technique, for an operational transconductance amplifier (OTA), has been proposed. This adds a current steering branch parallel to the differential pair, with a view to reducing the noise contribution by the cascode current sources. Hence, this reduces the overall input referred noise of the Low Noise Amplifier (LNA), without adding any additional power. The proposed technique implemented in 65nm CMOS technology achieves 30dB closed loop voltage gain, 0.05Hz lower cut-off frequency and 100MHz 3-dB bandwidth. It operates at 1.2V power supply and draws 1µA static current. The prototype described in this paper occupies 3300µm2silicon area

    An integrative comparative study between ultrasound-guided regional anesthesia versus parenteral opioids alone for analgesia in emergency department patients with hip fractures: A systematic review and meta-analysis

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    BackgroundEmergency physicians play a major role in managing patients with hip fractures. The most commonly used pain management option is parenteral opioids. However, parenteral opioids are subjected to several adverse effects. New pain management techniques such as regional anesthesia are used as alternatives to parenteral opioids. Anatomical landmarks were used to administer regional anesthesia; however, ultrasound guidance has shown promising results with regional anesthesia. Objectiveof the Review: The present study compares the efficacy of ultrasound-guided regional anesthesia (USGRA) to parenteral opioids in analgesia of hip fractures patients. MethodsA literature search for original and relevant articles carried out through six electronic databases, yielded 710 articles which were then assessed using the eligibility criteria resulting in 8 studies eligible for inclusion. ResultsA Meta-analysis of the seven studies showed that ultrasound-guided femoral nerve block was more effective than parenteral opioids in relieving pain. Similarly, meta-analysis of data from two studies shows that US-guided FICB significantly reduced pain scores than parenteral opioids. A subgroup analysis of adverse events showed no significant difference in nausea/vomiting and respiratory complications. However, a subgroup analysis on hypotension showed that the incidence of hypotension was significantly lower in USGRA than parenteral opioids. The present study also revealed that patients in the USGRA group required less frequent rescue analgesia than the patients in the parenteral opioids group. ConclusionResults of the present study show that USGRA is superior to parenteral opioids in reducing pain and the need for rescue analgesia in patients with hip fractures.The publication of this article is funded by the Qatar National Library

    Airway Management in COVID-19 as Aerosol Generating Procedure

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    2020 has seen the whole world battling a pandemic. Coronavirus Disease 2019 (COVID-19) is primarily transmitted through respiratory droplets when in close contact with an infected person, by direct contact, or by contact with contaminated objects and surfaces. Aerosol generating procedures (AGPs) like intubation have a high chance of generating large concentrations of infectious aerosols. AGPs potentially put healthcare workers at an increased risk of contracting the infection, and therefore special precautions are necessary during intubation. The procedure has to be performed by an expert operator who uses appropriate personal protective equipment (PPE). Modifications of known techniques have helped to reduce the chances of contracting the infection from patients. The use of checklists has become standard safe practice. This chapter looks at the current knowledge we have regarding this illness and how we should modify our practice to make managing the airway both safer for the patient and the healthcare workers involved. It addresses the preparation, staff protection, technical aspects and aftercare of patients who need airway intervention. It recommends simulation training to familiarize staff with modifications to routine airway management

    On Finslerized Absolute Parallelism spaces

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    The aim of the present paper is to construct and investigate a Finsler structure within the framework of a Generalized Absolute Parallelism space (GAP-space). The Finsler structure is obtained from the vector fields forming the parallelization of the GAP-space. The resulting space, which we refer to as a Finslerized Parallelizable space, combines within its geometric structure the simplicity of GAP-geometry and the richness of Finsler geometry, hence is potentially more suitable for applications and especially for describing physical phenomena. A study of the geometry of the two structures and their interrelation is carried out. Five connections are introduced and their torsion and curvature tensors derived. Some special Finslerized Parallelizable spaces are singled out. One of the main reasons to introduce this new space is that both Absolute Parallelism and Finsler geometries have proved effective in the formulation of physical theories, so it is worthy to try to build a more general geometric structure that would share the benefits of both geometries.Comment: Some references added and others removed, PACS2010, Typos corrected, Amendemrnts and revisions performe
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