35,262 research outputs found
Low Momentum Classical Mechanics with Effective Quantum Potentials
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
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
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.
© 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^*
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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What Proportion of Time is a particular Market inefficient?...Analysing market efficiency when equity prices follow Threshold Autoregressions.
We assume that log equity prices follow multi-state threshold autoregressions and generalize existing results for threshold autoregressive models, presented in Knight and Satchell (2012) for the existence of a stationary process and the conditions necessary for the existence of a mean and a variance; we also present formulae for these moments. Using a simulation study we explore what these results entail with respect to the impact they can have on tests for detecting bubbles or market efficiency. We find that bubbles are easier to detect in processes where a stationary distribution does not exist. Furthermore, we explore how threshold autoregressive models with i.i.d trigger variables may enable us to identify how often asset markets are inefficient. We find, unsurprisingly, that the fraction of time spent in an efficient state depends upon the full specification of the model; the notion of how efficient a market is, in this context at least, a model-dependent concept. However, our methodology allows us to compare efficiency across different asset markets
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