A causal look into the quantum Talbot effect

A well-known phenomenon in both optics and quantum mechanics is the so-called Talbot effect. This near field interference effect arises when infinitely periodic diffracting structures or gratings are illuminated by highly coherent light or particle beams. Typical diffraction patterns known as quantum carpets are then observed. Here the authors provide an insightful picture of this nonlocal phenomenon as well as its classical limit in terms of Bohmian mechanics, also showing the causal reasons and conditions that explain its appearance. As an illustration, theoretical results obtained from diffraction of thermal He atoms by both N-slit arrays and weak corrugated surfaces are analyzed and discussed. Moreover, the authors also explain in terms of what they call the Talbot-Beeby effect how realistic interaction potentials induce shifts and distortions in the corresponding quantum carpets.Comment: 12 pages, 6 figure

Classical Singularities In Chaotic Atom-Surface Scattering

In this paper we show that the diffraction condition for the scattering of atoms from surfaces leads to the appearance of a distinct type of classical singularity. Moreover, it is also shown that the onset of classical trapping or classical chaos is closely related to the bifurcation set of the diffraction-order function around the surface points presenting the rainbow effect. As an illustration of this dynamic, application to the scattering of He atoms by the stepped Cu(115) surface is presented using both a hard corrugated one-dimensional wall and a soft corrugated Morse potential

Surface Structure of Bi(111) from Helium Atom Scattering Measurements. Inelastic Close-Coupling Formalism

8 págs.; 4 figs.; 2 tabs.; Open Access funded by Creative Commons Atribution Licence 4.0© 2015 American Chemical Society. Elastic and inelastic close-coupling (CC) calculations have been used to extract information about the corrugation amplitude and the surface vibrational atomic displacement by fitting to several experimental diffraction patterns. To model the three-dimensional interaction between the He atom and the Bi(111) surface under investigation, a corrugated Morse potential has been assumed. Two different types of calculations are used to obtain theoretical diffraction intensities at three surface temperatures along the two symmetry directions. Type one consists of solving the elastic CC (eCC) and attenuating the corresponding diffraction intensities by a global Debye-Waller (DW) factor. The second one, within a unitary theory, is derived from merely solving the inelastic CC (iCC) equations, where no DW factor is necessary to include. While both methods arrive at similar predictions for the peak-to-peak corrugation value, the variance of the value obtained by the iCC method is much better. Furthermore, the more extensive calculation is better suited to model the temperature induced signal asymmetries and renders the inclusion for a second Debye temperature for the diffraction peaks futile.This research was supported by the European Commission and the Styrian Government within the ERDF program. S.M.A. acknowledges MICINN (Spain) through Grant No. FIS2011- 29596-C02-01. A.T. acknowledges financial support provided by the FWF (Austrian Science Fund) within the project J3479- N20.Peer Reviewe

Influencia del riego deficitario controlado precosecha sobre la calidad de la cereza ´Prime Giant`

El uso de redes de sensores para el manejo del riego deficitario controlado (RDC) en cerezo puede incidir en la mejora de la productividad del agua, calidad de la fruta y en su comportamiento poscosecha, al permitir el conocimiento y control del estado hídrico del suelo y árbol en todo momento. En el primer año de ensayo, el riego deficitario aplicado en precosecha para satisfacer el 85% de las necesidades máximas del cultivo (ETcg) permitió un ahorro de agua del 17% (380 m3 ha-1) respecto al tratamiento control, que se regó al 110% de la ETcg. Este déficit hídrico ligero no afectó a la producción (16,13 t ha-1) e incluso mejoró la calidad del fruto. Así, en el momento de la cosecha (t0) los frutos bajo déficit ligero presentaron matices más rojos y mayor acidez que los de riego completo. Esta mayor acidez no afectó al índice de madurez debido a la compensación por sólidos solubles totales (SST). El carácter de mayor acidez perduró tras 30 días de conservación en frio (t1) y 5 días de simulación de las condiciones de comercialización (t2). Igualmente, los frutos bajo déficit hídrico presentaron una tendencia a menores pérdidas de peso por deshidratación a finales de los periodos de conservación en frio y de simulación de la comercialización.Ministerio de Economía y Competitividad AGL2013-49047-C2-1

Generalized Arago-Fresnel laws: The EME-flow-line description

We study experimentally and theoretically the influence of light polarization on the interference patterns behind a diffracting grating. Different states of polarization and configurations are been considered. The experiments are analyzed in terms of electromagnetic energy (EME) flow lines, which can be eventually identified with the paths followed by photons. This gives rise to a novel trajectory interpretation of the Arago-Fresnel laws for polarized light, which we compare with interpretations based on the concept of "which-way" (or "which-slit") information.Comment: 14 pages, 6 figure

Prospective study of asbestos-related diseases incidence cases in primary health care in an area of Barcelona province

<p>Abstract</p> <p>Background</p> <p>Asbestos related diseases include a number of conditions due to inhalation of asbestos fibres at work, at home or in the environment, such as pleural mesothelioma, asbestosis and calcified pleural plaques. Few epidemiological studies have established the incidence of asbestos related diseases in our area. The present proposal is based on a retrospective study externally funded in 2005 that is currently taking place in the same area and largely carried out by the same research team.</p> <p>The aim of the study is to achieve a comprehensive and coordinated detection of all new cases of Asbestos Related Diseases presenting to primary care practitioners.</p> <p>Methods/design</p> <p>This is a multicentre, multidisciplinary and pluri-institutional prospective study.</p> <p><b>Setting</b></p> <p>12 municipalities in the Barcelona province within the catchment area of the health facilities that participate in the study.</p> <p><b>Sample</b></p> <p>This is a population based study, of all patients presenting with diseases caused by asbestos in the study area.</p> <p><b>Measurements</b></p> <p>A clinical and epidemiological questionnaire will be filled in by the trained researchers after interviewing the patients and examining their clinical reports.</p> <p>Discussion</p> <p>Data on the incidence of the different Asbestos Related Diseases in this area will be obtained and the most plausible exposure source and space-time-patient profile will be described. The study will also improve the standardization of patient management, the coordination between health care institutions and the development of preventive activities related with asbestos exposure and disease.</p