35,262 research outputs found

    Low Momentum Classical Mechanics with Effective Quantum Potentials

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    A recently introduced effective quantum potential theory is studied in a low momentum region of phase space. This low momentum approximation is used to show that the new effective quantum potential induces a space-dependent mass and a smoothed potential both of them constructed from the classical potential. The exact solution of the approximated theory in one spatial dimension is found. The concept of effective transmission and reflection coefficients for effective quantum potentials is proposed and discussed in comparison with an analogous quantum statistical mixture problem. The results are applied to the case of a square barrier.Comment: 4 figure

    Hyperbolic Metamaterial Resonator-Antenna Scheme for Large, Broadband Emission Enhancement and Single Photon Collection

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    We model the broadband enhancement of single-photon emission from color centres in silicon carbide nanocrystals coupled to a planar hyperbolic metamaterial, HMM resonator. The design is based on positioning the single photon emitters within the HMM resonator, made of a dielectric index-matched with silicon-carbide material. The broadband response results from the successive resonance peaks of the lossy Fabry Perot structure modes arising within the high-index HMM cavity. To capture this broadband enhancement in the single photon emitters spontaneous emission, we placed a simple gold based cylindrical antenna on top of the HMM resonator. We analyzed the performance of this HMM coupled antenna structure in terms of the Purcell enhancement, quantum efficiency, collection efficiency and overall collected photon rate. For perpendicular dipole orientation relative to the interface, the HMM coupled antenna resonator leads to a significantly large spontaneous emission enhancement with Purcell factor of the order of 250 along with a very high average total collected photon rate, CPR of about 30 over a broad emission spectrum, 700 nm to 1000 nm. The peak CPR increases to about 80 at 900 nm, corresponding to the emission of silicon-carbide quantum emitters. This is a state of the art improvement considering the previous computational designs have reported a maximum average CPR of 25 across the nitrogen-vacancy centre emission spectrum, 600 nm to 800 nm with the highest value being about 40 at 650 nm

    Comparative Biodegradability Assessment of Different Types of paper

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    Production and use of paper materials are excessively increasing with the development of civilization thereby making its disposal challenging. It is very important to have an accurate indication of the rate of different types of paper decay which would ultimately assist the waste management sector. The study investigates the rate of biodegradation of four available grades of paper in a captive compost environment. To investigate this, the papers were cut into strips according to the test specification and buried into the compost soil to let them biodegrade. Sampling was done periodically at certain sampling points to measure the extent of biodegradation by measuring tensile strength with a “tensometer”. The tensile strength data of the experimental strips was compared with the same of controls (unburied) and also among the paper types by using different statistical methods. The result demonstrated that the recycled paper degrades more quickly followed by glossy papers, which take some more days to degrade utterly. The higher rate of biodegradation of recycled paper might have occurred due to its chemical pulping where chlorine is normally used as bleaching agent. The glossy paper also degraded promptly at its 1st and 3rd day of burial but took some more days to degrade completely. The reason may be the starch coating has accelerated the biodegradation at initial stage. The newsprint with ink did not fully biodegrade even after 21 days while newsprint without ink take 16 days to vanish. It is assumed that the lignin and ink content of newsprint without ink and newsprint with ink respectively may have inhibited biodegradation. To sum up, composition of principle raw materials and processing style contributes significantly in biodegradability of paper products. Composting, an eco-friendly option can solve the paper disposal problem which reduces the landfill cost and at the same time produces good quality marketable compost. Keywords: Biodegradability Assessment; Biodegradation; Composting; Waste Management

    Construing and body dissatisfaction in chronic depression: a study of body psychotherapy.

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    © 2018 Elsevier B.V. All rights reserved.The frequent association of depression with somatic symptoms suggests that body psychotherapy may be an appropriate therapeutic intervention for people with chronic depression. Using a subset of twenty-three participants from a randomized controlled trial that had demonstrated the effectiveness of such an intervention in reducing depressive symptoms, the present study investigated whether it may also impact aspects of construing which have been associated with depression. Patients presenting with chronic depression were randomly allocated to a treatment group or a waiting list group, which received body psychotherapy after a period on a waiting list. Correlations between repertory grid, questionnaire, and visual analogue measures indicated that depression and bodily dissatisfaction were associated with features of the content and structure of construing. There were no significant changes while patients were on the waiting list, but during treatment reduction in depression and bodily dissatisfaction, together with increase in self-esteem and quality of life, were accompanied by an increase in the salience of construing of the bodily self.Peer reviewe

    Fourth-generation SM imprints in B -> K^*l^+l^- decays with polarized K^*

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    The implication of the fourth-generation quarks in the B -> K^*l^+l^- (l=mu,tau) decays, when K^* meson is longitudinally or transversely polarized, is presented. In this context, the dependence of the branching ratio with polarized K^* and the helicity fractions (f_{L,T}) of K^* meson are studied. It is observed that the polarized branching ratios as well as helicity fractions are sensitive to the NP parameters, especially when the final state leptons are tauons. Hence the measurements of these observables at LHC can serve as a good tool to investigate the indirect searches of new physics beyond the Standard Model.Comment: 13 pages, 10 figures, V2: some of the graphs are modified according to the new data from recent experiments. arXiv admin note: substantial text overlap with arXiv:1107.569
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