Even harmonic generation in isotropic media of dissociating homonuclear molecules

Isotropic gases irradiated by long pulses of intense IR light can generate very high harmonics of the incident field. It is generally accepted that, due to the symmetry of the generating medium, be it an atomic or an isotropic molecular gas, only odd harmonics of the driving field can be produced. Here we show how the interplay of electronic and nuclear dynamics can lead to a marked breakdown of this standard picture: a substantial part of the harmonic spectrum can consist of even rather than odd harmonics. We demonstrate the effect using ab-initio solutions of the time-dependent Schr\"odinger equation for $H$$_2$$^+$ and its isotopes in full dimensionality. By means of a simple analytical model, we identify its physical origin, which is the appearance of a permanent dipole moment in dissociating homonuclear molecules, caused by light-induced localization of the electric charge during dissociation. The effect arises for sufficiently long laser pulses and the region of the spectrum where even harmonics are produced is controlled by pulse duration. Our results (i) show how the interplay of femtosecond nuclear and attosecond electronic dynamics, which affects the charge flow inside the dissociating molecule, is reflected in the nonlinear response, and (ii) force one to augment standard selection rules found in nonlinear optics textbooks by considering light-induced modifications of the medium during the generation process.Comment: 7 pages, 6 figure

Recent Approaches for the Determination of Forming Limits by Necking and Fracture in Sheet Metal Forming

Forming limit diagrams (FLD’s) are used to evaluate the workability of metal sheets. FLD’s provide the failure locus at which plastic instability occurs and localized necking develops (commonly designated as the forming limit curve - FLC), and the failure loci at the onset of fracture by tension (FFL) or by in-plane shear (SFFL). The interest of metal formers in controlling localized necking is understandable because the consequence of plastic instability is an undesirable surface blemish in components. However, because under certain loading conditions fracture can precede necking in sheet metal forming processes, there is a growing interest in characterizing the forming limits by necking and fracture in the FLD’s. This paper gathers together a number of recently developed methodologies for detecting the onset of local necking and fracture by in-plane tension or in-plane shear, and discusses their applicability to determine experimentally the FLC’s, FFL’s and SFFL’s.Ministerio de Economía y Competitividad DPI2012-3291

An algebraic approach to the minimum-cost multi-impulse orbit transfer problem

A purely algebraic formulation (i.e., polynomial equations only) of the minimum-cost multi-impulse orbit-transfer problem without time constraints is presented, while keeping all the variables with a precise physical meaning. General algebraic techniques are applied to solve these equations (resultants, Gröbner bases, etc.) in several situations of practical interest of different degrees of generality. For instance, a proof of the optimality of the Hohmann transfer for the minimum-fuel two-impulse circular-to-circular orbit-transfer problem is provided. Finally, a general formula is also provided for the optimal two-impulse in-plane transfer between two rotated elliptical orbits under a mild symmetry assumption on the two points where the impulses are applied (which, it is conjectured, can be removed)

Vingt ans de protection des rivières sur la côte de la région de Murcie (1994-2014 ). Évaluation de l'efficacité des mesures de planification

A significant increase in episodes of flooding on the coast of Murcia occurred in last decades, questioning the role of preventive strategies on planning. In this paper is evaluated the efficiency of river channel protection actions included in the Guidelines and Planning of Región de Murcia Coast. The cadastral information and the hydrological modeling of 10, 50, 100 and 500 years of return period have been used to study the evolution of vulnerability. The results shows that exposure to risk has continued to increase even after the adoption of these guidelines, becoming a key factor in the increase of economic losses associated with flooding.En las últimas décadas se ha producido un incremento significativo de los episodios de inundación en el litoral de la Región de Murcia que hace cuestionar el papel desempeñado por las estrategias preventivas de ordenación. En este trabajo se evalúa la eficiencia de las medidas de protección de cauces incluidas en las Directrices y Plan de Ordenación del Litoral de la Región de Murcia. Para ello se utiliza la información catastral y la modelización hidrológica del periodo de retorno de 10, 50, 100 y 500 años. Los resultados demuestran que la exposición al peligro ha seguido aumentando incluso después de la aprobación de dicho instrumento y nos permiten evidenciar al aumento de la exposición y la vulnerabilidad como factores principales en dicha acentuación de las pérdidas económicas asociadas a inundaciones.Au cours des dernières décennies, on a pu constater un accroissement significatif des épisodes d'innodation au long du littoral de la région de Murcia. Cet accroissement met en question le rôle des stratégies préventives d'ordonnance. Ce travail évalue l'efficacité des mesures de protection des lits inclues dans les directrices et le plan d'ordonnance du littoral de la région de Murcia. À cet effet, on utilise l'information cadastrale et la modélisation hydrologique de la période de retour de 10, 50, 100 et 500 ans. Les résultats prouvent que l'exposition au danger a continué à augmenter même après l'approbation de tel instrument et nous permettent de mettre en évidence l' exposition croissante et la vulnérabilité comme principaux facteurs de cette accentuation des pertes économiques associées aux innondations

Fingerprinting Chamaesiphon populations as an approach toassess the quality of running waters

"This is the peer reviewed version of the following article: Loza, V.; Morales, A.; Perona, E. and Muñoz-Martín, M. A."Fingerprinting Chamaesiphon populations as an approach toassess the quality of running waters" River Research and Applications 34 (2018): 595-605 which has been published in final form at https://doi.org/10.1002/rra.3277. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions."Cyanobacterial communities are highly diverse in freshwaters and respond rapidly tochanging environments. Previous studies have highlighted variations in the structureand composition of epilithic cyanobacterial communities in response to eutrophica-tion in watercourses. In the present study, changes in benthic cyanobacterial commu-nities from Guadalix River (Spain) biofilms were examined using temperature‐gradientgel electrophoresis (TGGE) in conjunction with microscopic examination of field‐fixedsamples, focusing on populations of one of the dominant cyanobacteria:Chamaesiphon. Environmental characteristics were determined in order to character-ize the trophic status of the sampling sites. The presence of cyanobacteria in the riverwas determined from complex TGGE patterns, band extraction, and subsequentsequencing of 16S rDNA gene fragments. The microscopic observations revealed thatthe unicellular genus Chamaesiphon and the filamentous genus Phormidium were dom-inant in the studied locations. Within the 2 genera, 4 Chamaesiphon populations wereidentified (Chamaesiphon fuscus, Chamaesiphon starmachii, Chamaesiphon subglobosus ,and Chamaesiphon polymorphus) and Phormidium was represented at the samplingsites by the Phormidium autumnale morphotype. TGGE banding patterns differedamong samplings sites as a function of water quality. The genetic analysis revealed4 phylotypes within the genus Chamaesiphon and 1 phylotype within the classicP. autumnale clade. Chamaesiphon phylotypes were not equally distributed in all thesampling locations. Some phylotypes were related to low nutrient concentrations,while others were associated with eutrophic conditions. Our results support the useof fingerprints of Chamaesiphon populations obtained by TGGE to examine changesin water quality.This work was supported by Grant CGL2013‐44870‐R from the Ministerio de Economía y Competitividad, Spai

Upper body motor function and swallowing impairments and its association in survivors of head and neck cancer: A cross-sectional study

Background Upper body motor function and swallowing may be affected after curative treatment for head and neck cancer. The aims of this study are to compare maximum mouth opening (MMO), temporomandibular dysfunction (TMD), cervical and shoulder active range of motion (AROM) and strength, and swallowing difficulty between survivors of head and neck cancer (sHNC) and healthy matched controls (HMC) and to examine the correlations between these outcomes in sHNC. Methods Thirty-two sHNC and 32 HMC participated on the study. MMO, TMD, cervical and shoulder AROM, cervical and shoulder strength, the SPADI shoulder pain and disability indices, the Eating Assessment Tool (EAT-10) score, swallowing difficulty as determined using a visual analogue scale (VAS), and the location of disturbances in swallowing, were recorded. Results MMO and cervical and shoulder AROM and strength were significantly lower in sHNC, whereas FAI, SPADI score, EAT-10 and VAS were higher. The MMO, TMD, cervical and shoulder AROM, and cervical shoulder strength values showed significant correlations (some direct, others inverse) with one another. Swallowing difficulty was inversely associated with the MMO, cervical AROM and shoulder strength. Conclusion Compared with controls, sHNC present smaller MMO, lower cervical and shoulder AROM, lower cervical and shoulder strength and higher perception of TMD, shoulder pain and disability and swallowing difficulty. sHNC suffer impaired swallowing related to lower MMO, presence of TMD, cervical AROM and shoulder strength values. Improving these variables via physiotherapy may reduce the difficulty in swallowing experienced by some sHNC.Fondos Estructurales de la Union Europea (FEDER)Unit of Excellence on Exercise and Health (UCEES), University of Granad

Work related stress and well-being: the roles of direct action coping and palliative coping

The purpose of the present study is to analyze the roles of direct action coping and palliative coping in the relationship between work stressors and psychological well-being, as well as their possible interactions, in a sample of 464 bank employees. Hierarchical regression analyses showed main effects of direct action coping on well-being. Palliative coping predicts higher levels of psychological distress. Contrary to what was expected, the interactions between work stressors and direct action coping were not significant. Palliative coping interacted with work stressors when predicting psychosomatic complaints. The interaction between the two types of coping was significant on psychosomatic complaints and psychological distress, but not on job satisfaction. The paper discusses theoretical and practical implications of these results, in order to design intervention strategies to prevent and manage job stress