636 research outputs found

    Single-input Multiple-output Signals Third-order Active-R Filter for different Circuit Merit Factor (Q)

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    Single-input Multiple-output Signals Third-order Active-R Filter for different Circuit Merit Factor Q Configuration is proposed. This paper discusses a new configuration to realize third-order low pass, band pass and high pass. The presented circuit uses Single-input Multiple-output signals, OP-AMP and passive components. This filter is useful for high frequency operation, monolithic IC implementation and it is easy to design .This circuit gives three filter functions low-pass, high-pass and band-pass. This filter circuit can be used for different merit factor (Q) with high pass band gain. This gives better stop-band attenuation and sharper cut-off at the edge of the pass-band. Thus the response shows wider pass-band. The Ideal value of this filter circuit which is closed to Ideal value of third-order active-R filter is at 0.8? Q ?6. The advantages of this circuit are reduction in size and weight, increased circuit reliability, more economical and easy for manufacturing

    On Existence and Uniqueness Theorem Concerning Time–Dependent Heat Transfer Model

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    In this article we consider a physical model describing time-dependent heat transfer by conduction and radiation. This model contains two conducting and opaque materials which are in contact by radiation through a transparent medium bounded by diffuse-grey surfaces. The aim of this work is to present a reliable framework to prove the existence and the uniqueness of a weak solution for this problem. The existence of the solution can be proved by solving an auxiliary problem by the Galerkin-based approximation method and Moser-type arguments which implies the existence of solution to the original problem. The uniqueness of the solution will be proved by using the same approach in our previous work for the stationary heat transfer model and some ideas from nonlinear heat conduction analysis

    Copper trafficking in eukaryotic systems: current knowledge from experimental and computational efforts

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    Copper plays a vital role in fundamental cellular functions, and its concentration in the cell must be tightly regulated, as dysfunction of copper homeostasis is linked to severe neurological diseases and cancer. This review provides a compendium of current knowledge regarding the mechanism of copper transfer from the blood system to the Golgi apparatus; this mechanism involves the copper transporter hCtr1, the metallochaperone Atox1, and the ATPases ATP7A/B. We discuss key insights regarding the structural and functional properties of the hCtr1-Atox1-ATP7B cycle, obtained from diverse studies relying on distinct yet complementary biophysical, biochemical, and computational methods. We further address the mechanistic aspects of the cycle that continue to remain elusive. These knowledge gaps must be filled in order to be able to harness our understanding of copper transfer to develop therapeutic approaches with the capacity to modulate copper metabolism

    The outskirts of globular clusters as modified gravity probes

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    In the context of theories of gravity modified to account for the observed dynamics of galactic systems without the need to invoke the existence of dark matter, a prediction often appears regarding low acceleration systems: wherever aa falls below a0a_{0} one should expect a transition from the classical to the modified gravity regime.This modified gravity regime will be characterised by equilibrium velocities which become independent of distance, and which scale with the fourth root of the total baryonic mass, V4MV^{4} \propto M. The two above conditions are the well known flat rotation curves and Tully-Fisher relations of the galactic regime. Recently however, a similar phenomenology has been hinted at, at the outskirts of Galactic globular clusters, precisely in the region where a<a0a<a_{0}. Radial profiles of the projected velocity dispersion have been observed to stop decreasing along Keplerian expectations, and to level off at constant values beyond the radii where a<a0a<a_{0}. We have constructed gravitational equilibrium dynamical models for a number of globular clusters for which the above gravitational anomaly has been reported, using a modified Newtonian force law which yields equilibrium velocities equivalent to MOND. We find models can be easily constructed having an inner Newtonian region and an outer modified gravity regime, which reproduce all observational constraints, surface brightness profiles, total masses and line of sight velocity dispersion profiles. Through the use of detailed single stellar population models tuned individually to each of the globular clusters in question, we derive estimates of the total masses for these systems. Interestingly, we find that the asymptotic values of the velocity dispersion profiles are consistent with scaling with the fourth root of the total masses, as expected under modified gravity scenarios.Comment: Accepted in ApJ, 13 pages, 7 figure

    The role of website experience in building attitude and intention towards online shopping

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    Since technology has become an inseparable part of consumers’ lives, understanding acceptance and use of technology at individual consumer level has become a must for marketing theory and practice. To explain consumers’ acceptance of a new technology, the present study uses the unified theory of acceptance and use of technology (UTAUT) as the theoretical foundation. It then proposes extending UTAUT through incorporating a hedonic dimension, which should be an important predictor in explaining technology acceptancy in a consumer context such as on-line shopping, especially where experiential products—like apparel—are involved. The proposed hedonic dimension is perceived playfulness, which itself has two first-order latent antecedents; vividness and embodied cognition. Vividness —visual in this case—is related to the vividness of the shopping environment as represented on-line and to what extent its visual cues stimulate consumers to form strong (as opposed to weak) mental images of the product that they seek to buy. Embodied cognition represents the relationship between the pre-existing knowledge that is saved in mind and body. The present study also reintroduces attitude to the model as an important construct in predicting purchase intention. To test the proposed model’s ability to explain technology acceptance in different cultural contexts, the model is empirically tested via an experiment and a survey in a western country—the UK—and a non-western country—The Hashemite Kingdom of Jordan (HKJ). Two hundred and twenty two questionnaires are collected from the UK and 258 questionnaires are collected from the HKJ. Findings suggest that the incorporated hedonic dimension is as important as the utilitarian dimension in explaining technology acceptance in consumer context in both western and non-western countries. A positive relationship between perceived playfulness and purchase intention is found. However, attitude is partially mediating the relationship between perceived playfulness and purchase intention. Social influence is also found to be a predictor of attitude in the HKJ, but not in the UK. Theoretical and practical contributions of these findings are exhibited and roots of future research are proposed

    Oleuropein Is Responsible for the Major Anti-Inflammatory Effects of Olive Leaf Extract

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    Olive leaves are rich in polyphenolic compounds that are known to have antioxidant, antimicrobial, and antiinflammatory activities. Therefore, olive leaf extract (OLE) is considered as a natural supplement. In this study we evaluated the antibacterial and the anti-inflammatory effect of OLE and its individual phenolic components in vitro. Polymorphonuclear cells (PMNCs) were isolated from the whole blood using Histopaque solution and cultured in RPMI-enriched medium. Tumor necrosis factor a (TNFa) level was determined by ELISA after 24 h of lipopolysaccharide stimulation. The antibacterial activity of OLE was determined by well diffusion assay. We found a significant decrease in TNFa secretion level in PMNCs culture treated with OLE. Oleuropein is the only OLE component that has shown anti-inflammatory effects at a concentration of 20 lg/mL. Furthermore, OLE exhibited antibacterial activity against some gram positive bacterial strains; however, gram negative bacterial strains were resistant to OLE. Downregulation of TNFa secretion in PMNCs culture in response to OLE treatment indicates that this polyphenol-rich extract has an anti-inflammatory effect, and oleuropein is the major OLE component responsible for this effect. The antibacterial activity of OLE is limited to gram positive bacteria.Our thanks are due to all laboratory members who participated in this study

    Comparison between Analytical Equation and Numerical Methods for Determining Shear Stress in a Cantilever Beam

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    A three meter-length cantilever beam loaded with a concentrated load at its free end is studied to determine shear stresses. In the present study, three cross sections are considered: rectangle (R); I, and T. The study presents a comparison of maximum shear stresses obtained by means of two methods: classical analytical equation derived by Collingnon, and finite element method (FEM) software. Software programs ANSYS and SAP2000 were used. The results show difference between the maximum shear stresses obtained by the analytical equation and the software, being the last is always higher. The average differences for ANSYS and SAP2000, independently of the cross section, were 12.76% and 11.96%, respectively. Considering these differences, correction factors were proposed to the classical analytical formula for each cross section case to obtain more realistic results. After the correction, the average differences decrease to 1.48% and 4.86%, regardless of the cross section shape
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