2,073 research outputs found

    Quantum Zeno effect by indirect measurement: The effect of the detector

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    We study the quantum Zeno effect in the case of indirect measurement, where the detector does not interact directly with the unstable system. Expanding on the model of Koshino and Shimizu [Phys. Rev. Lett., 92, 030401, (2004)] we consider a realistic Hamiltonian for the detector with a finite bandwidth. We also take explicitly into account the position, the dimensions and the uncertainty in the measurement of the detector. Our results show that the quantum Zeno effect is not expected to occur, except for the unphysical case where the detector and the unstable system overlap.Comment: 4 pages, 4 figure

    Carob Pods (Ceratonia siliqua L.) as a Source of Polyphenolic Antioxidants

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    The possibility of utilising chopped and deseeded carob pods (kibbles) as a source of polyphenolic antioxidants was examined by performing extractions with various solvent systems, in order to evaluate and optimize the conditions for the recovery of polyphenols. Maximum quantities of polyphenolic components were found in 80 % acetone extracts, as evaluated by measuring total polyphenol and total flavanol content. By contrast, ethyl acetate was inefficient in extracting polyphenols. The assessment of the antioxidant potency of carob pod extracts employing two characteristic in vitro models showed that carobs contain polyphenols with appreciable antiradical and reducing properties. The values obtained were compared to the data on red wines and pure polyphenolic antioxidants

    Carob Pods (Ceratonia siliqua L.) as a Source of Polyphenolic Antioxidants

    Get PDF
    The possibility of utilising chopped and deseeded carob pods (kibbles) as a source of polyphenolic antioxidants was examined by performing extractions with various solvent systems, in order to evaluate and optimize the conditions for the recovery of polyphenols. Maximum quantities of polyphenolic components were found in 80 % acetone extracts, as evaluated by measuring total polyphenol and total flavanol content. By contrast, ethyl acetate was inefficient in extracting polyphenols. The assessment of the antioxidant potency of carob pod extracts employing two characteristic in vitro models showed that carobs contain polyphenols with appreciable antiradical and reducing properties. The values obtained were compared to the data on red wines and pure polyphenolic antioxidants

    Resistant Hypertension Workup and Approach to Treatment

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    Resistant hypertension is defined as blood pressure above the patient's goal despite the use of 3 or more antihypertensive agents from different classes at optimal doses, one of which should ideally be a diuretic. Evaluation of patients with resistive hypertension should first confirm that they have true resistant hypertension by ruling out or correcting factors associated with pseudoresistance such as white coat hypertension, suboptimal blood pressure measurement technique, poor adherence to prescribed medication, suboptimal dosing of antihypertensive agents or inappropriate combinations, the white coat effect, and clinical inertia. Management includes lifestyle and dietary modification, elimination of medications contributing to resistance, and evaluation of potential secondary causes of hypertension. Pharmacological treatment should be tailored to the patient's profile and focus on the causative pathway of resistance. Patients with uncontrolled hypertension despite receiving an optimal therapy are candidates for newer interventional therapies such as carotid baroreceptor stimulation and renal denervation

    Polyphenolic burden and in vitro antioxidant properties of Moringa oleifera root extracts

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    ntroduction: Moringa oleifera is a small tree with very significant nutritional but alsopharmacological properties and various preparations from almost all parts of the plant (leaves,fruit, stems, bark, roots) are used in folk medicine for treating several ailments. This study aimedto investigating the polyphenolic burden and in vitro antioxidant properties of M. oleifera rootextracts, obtained with solvents covering a range of polarities.Methods: Lyophilised Moringa oleifera roots were extracted with solvents of increasing polarity,including ethyl acetate, butanol, methanol and water. The generated extracts were screened forpolyphenolic load and antioxidant activities, by determining the total polyphenol, total f lavonoid,total f lavanol, antiradical activity and reducing power. Liquid chromatography-mass spectrometrywas also employed to obtain some evidence regarding the nature of the main constituents.Results: The results indicated that both aqueous and methanolic extracts were the richestin total polyphenols, but the aqueous extract also exhibited high reducing power. The liquidchromatography-diode array-mass spectrometry analysis also revealed that the major substancesoccurring in the aqueous extract were relatively polar molecules, but the mass spectral data wereambiguous to assign tentative structures.Conclusion: Polar solvents, such as water, may be effectively used to recover high amounts of M.oleifera root phenolics, which possess important antioxidant properties.&nbsp

    Underwater Sound Characteristics of a Ship with Controllable Pitch Propeller

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    The time-dependent spectral characteristics of underwater sound radiated by an oceanic vessel have complex dependencies on ship machinery, propeller dynamics, and the hydrodynamics of the ship exhaust and motion, as well as onboard activities. Here, the underwater sound radiated by a ship equipped with a controllable pitch propeller (CPP) is analyzed and quantified via its (i) power spectral density for signal energetics, (ii) temporal coherence for machinery tonal sound, and (iii) spectral coherence for propeller amplitude-modulated cavitation noise. Frequency-modulated (FM) tonal signals are also characterized in terms of their frequency variations. These characteristics are compared for different propeller pitch ratios, ranging from 20% to 82% at a fixed number of propeller revolutions per minute (RPM). The efficacy and robustness of ship parameter estimation at different pitches are discussed. Finally, an analysis of one special measurement is provided: propeller pitch and RPM over the duration of the measurement when the ship changes speed. The 50% pitch was found to be a crucial point for this ship, around which the tonal characteristics of its underwater radiated sound attain their peak values while broadband sound and associated spectral coherences are at a minimum. The findings here elucidate the effects of pitch variation on underwater sound radiated by ships with controllable pitch propellers and has applications in ship design and underwater noise mitigation

    Hybrid Adaptive Filter development for the minimisation of transient fluctuations superimposed on electrotelluric field recordings mainly by magnetic storms

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    The method of Hybrid Adaptive Filtering (HAF) aims to recover the recorded electric field signals from anomalies of magnetotelluric origin induced mainly by magnetic storms. An adaptive filter incorporating neuro-fuzzy technology has been developed to remove any significant distortions from the equivalent magnetic field signal, as retrieved from the original electric field signal by reversing the magnetotelluric method. Testing with further unseen data verifies the reliability of the model and demonstrates the effectiveness of the HAF method
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