112 research outputs found

    On the analogy between the classical wave optics and the quantum wave phenomena

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    A striking correspondence between the effects of an auxiliary-mode-assisted transfer of light power between two waveguides and an auxiliary-state-assisted transfer of an electron between two quantum dots is highlighted by the example of an exactly solvable model.Comment: To appear in Solid State Communication

    The Medical Necessity for Medicinal Cannabis: Prospective, Observational Study Evaluating the Treatment in Cancer Patients on Supportive or Palliative Care

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    Background. Cancer patients using cannabis report better influence from the plant extract than from synthetic products. However, almost all the research conducted to date has been performed with synthetic products. We followed patients with a medicinal cannabis license to evaluate the advantages and side effects of using cannabis by cancer patients. Methods. The study included two interviews based on questionnaires regarding symptoms and side effects, the first held on the day the license was issued and the second 6–8 weeks later. Cancer symptoms and cannabis side effects were documented on scales from 0 to 4 following the CTCAE. The distress thermometer was used also. Results. Of the 211 patients who had a first interview, only 131 had the second interview, 25 of whom stopped treatment after less than a week. All cancer or anticancer treatment-related symptoms showed significant improvement (P<0.001). No significant side effects except for memory lessening in patients with prolonged cannabis use (P=0.002) were noted. Conclusion. The positive effects of cannabis on various cancer-related symptoms are tempered by reliance on self-reporting for many of the variables. Although studies with a control group are missing, the improvement in symptoms should push the use of cannabis in palliative treatment of oncology patients

    Time independent description of rapidly oscillating potentials

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    The classical and quantum dynamics in a high frequency field are found to be described by an effective time independent Hamiltonian. It is calculated in a systematic expansion in the inverse of the frequency (ω\omega) to order ω−4\omega^{-4}. The work is an extension of the classical result for the Kapitza pendulum, which was calculated in the past to order ω−2\omega^{-2}. The analysis makes use of an implementation of the method of separation of time scales and of a quantum gauge transformation in the framework of Floquet theory. The effective time independent Hamiltonian enables one to explore the dynamics in presence of rapidly oscillating fields, in the framework of theories that were developed for systems with time independent Hamiltonians. The results are relevant, in particular, for exploration of the dynamics of cold atoms.Comment: 4 pages, 1 figure. Revised versio

    An application of interpolating scaling functions to wave packet propagation

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    Wave packet propagation in the basis of interpolating scaling functions (ISF) is studied. The ISF are well known in the multiresolution analysis based on spline biorthogonal wavelets. The ISF form a cardinal basis set corresponding to an equidistantly spaced grid. They have compact support of the size determined by the underlying interpolating polynomial that is used to generate ISF. In this basis the potential energy matrix is diagonal and the kinetic energy matrix is sparse and, in the 1D case, has a band-diagonal structure. An important feature of the basis is that matrix elements of a Hamiltonian are exactly computed by means of simple algebraic transformations efficiently implemented numerically. Therefore the number of grid points and the order of the underlying interpolating polynomial can easily be varied allowing one to approach the accuracy of pseudospectral methods in a regular manner, similar to high order finite difference methods. The results of numerical simulations of an H+H_2 collinear collision show that the ISF provide one with an accurate and efficient representation for use in the wave packet propagation method.Comment: plain Latex, 11 pages, 4 figures attached in the JPEG forma

    Variation of the Epiphytic Lichen Diversity in a Gradient of Atmospheric Pollution: Do Taxonomic, Genetic, and Functional Distances between Species Add any Information? GENERAL BIOLOGY

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    22 Studying the influence of reduced biological diver sity on functioning and stability of ecosystems is one of the priorities of modern ecology If the distances between species are important for biodiversity assessment, then strong perturbations that disturb ecosystem equilibrium should lead to signifi cant differences between the indices of diversity and disparity. In this study, we aimed to test this hypothesis using the epiphytic lichen communities, which are extremely sensitive to atmospheric pollution of the biotic component

    Defining clinically important perioperative blood loss and transfusion for the Standardised Endpoints for Perioperative Medicine (StEP) collaborative: a protocol for a scoping review

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    INTRODUCTION: 'Standardised Endpoints for Perioperative Medicine' (StEP) is an international collaboration undertaking development of consensus-based consistent definitions for endpoints in perioperative clinical trials. Inconsistency in endpoint definitions can make interpretation of trial results more difficult, especially if conflicting evidence is present. Furthermore, this inconsistency impedes evidence synthesis and meta-analyses. The goals of StEP are to harmonise definitions for clinically meaningful endpoints and specify standards for endpoint reporting in clinical trials. To help inform this endeavour, we aim to conduct a scoping review to systematically characterise the definitions of clinically important endpoints in the existing published literature on perioperative blood loss and transfusion. METHODS AND ANALYSIS: The scoping review will be conducted using the widely adopted framework developed by Arksey and O'Malley, with modifications from Levac. We refined our methods with guidance from research librarians as well as researchers and clinicians with content expertise. The electronic literature search will involve several databases including Medline, PubMed-not-Medline and Embase. Our review has three objectives, namely to (1) identify definitions of significant blood loss and transfusion used in previously published large perioperative randomised trials; (2) identify previously developed consensus-based definitions for significant blood loss and transfusion in perioperative medicine and related fields; and (3) describe the association between different magnitudes of blood loss and transfusion with postoperative outcomes. The multistage review process for each question will involve two reviewers screening abstracts, reading full-text articles and performing data extraction. The abstracted data will be organised and subsequently analysed in an iterative process. ETHICS AND DISSEMINATION: This scoping review of the previously published literature does not require research ethics approval. The results will be used to inform a consensus-based process to develop definitions of clinically important perioperative blood loss and transfusion. The results of the scoping review will be published in a peer-reviewed scientific journal

    Classical Simulation of Relativistic Quantum Mechanics in Periodic Optical Structures

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    Spatial and/or temporal propagation of light waves in periodic optical structures offers a rather unique possibility to realize in a purely classical setting the optical analogues of a wide variety of quantum phenomena rooted in relativistic wave equations. In this work a brief overview of a few optical analogues of relativistic quantum phenomena, based on either spatial light transport in engineered photonic lattices or on temporal pulse propagation in Bragg grating structures, is presented. Examples include spatial and temporal photonic analogues of the Zitterbewegung of a relativistic electron, Klein tunneling, vacuum decay and pair-production, the Dirac oscillator, the relativistic Kronig-Penney model, and optical realizations of non-Hermitian extensions of relativistic wave equations.Comment: review article (invited), 14 pages, 7 figures, 105 reference

    State-to-state transition probabilities for time-dependent Hamiltonians using complex absorbing potentials

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    . Earlier work has derived a new expression for the time-independent scattering probability for time-dependent Hamiltonians for cases where the motion is free at infinitely large times. Here we introduce a new technique which provides an efficient numerical algorithm for the calculation of multiphoton event probabilities based on using complex absorbing potentials along the scattering coordinate. The (t, t # ) method is used allowing an analytical propagation of the initial state and avoiding long propagation times and accumulation of numerical errors. An iterative technique for the solution of non-Hermitian linear systems is used which allows us to tackle large time-dependent systems, both in internal degrees of freedom and in the number of Fourier components in the time-dependent potential term. A numerical example illustrating the usefulness of the theory is given. 1. Introduction Numerical solution of the time-dependent Schr odinger equation has become one of the main tools of mol..

    BioBull3_02VorobeichikLO

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    Abstract -Contamination of the southern taiga forests (Middle Urals) by from cooper smelters (heavy metals combined with SO 2 ) not only decreases the mean rate of decomposition of pure cellulose, but also radically changes the spatial structure of the destruction process. Heterogeneity of distribution of the destruction rate is sharply increased near the source of emission due to differentiation of the space into microsites with high and low destruction rates. The range of spatial heterogeneity amounts to several tens of centimeters and the distribution of microsites with a high rate is random within several tens of meters. A hypothesis has been put forward that the described changes in the spatial structure of the destruction process are related, above all, to disturbed colonization of the substrate by soil microfungi. ECOLOG
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