396 research outputs found

    Climate trends and behaviour of drought indices based on precipitation and evapotranspiration in Portugal

    Get PDF
    Distinction between drought and aridity is crucial to understand water scarcity processes. Drought indices are used for drought identification and drought severity characterisation. The Standardised Precipitation Index (SPI) and the Palmer Drought Severity Index (PDSI) are the most known drought indices. In this study, they are compared with the modified PDSI for Mediterranean conditions (MedPDSI) and the Standardised Precipitation Evapotranspiration Index (SPEI). MedPDSI results from the soil water balance of an olive crop, thus real evapotranspiration is considered, while SPEI uses potential (climatic) evapotranspiration. Similarly to the SPI, SPEI can be computed at various time scales. Aiming at understanding possible impacts of climate change, prior to compare the drought indices, a trend analysis relative to precipitation and temperature in 27 weather stations of Portugal was performed for the period 1941 to 2006. A trend for temperature increase was observed for some weather stations and trends for decreasing precipitation in March and increasing in October were also observed for some locations. Comparisons of the SPI and SPEI at 9- and 12-month time scales, the PDSI and Med- PDSI were performed for the same stations and period. SPI and SPEI produce similar results for the same time scales concerning drought occurrence and severity. PDSI and Med- PDSI correlate well between them and the same happened for SPI and SPEI. PDSI and MedPDSI identify more severe droughts than SPI or SPEI and identify drought occurrence earlier than these indices. This behaviour is likely to be related with the fact that a water balance is performed with PDSI and MedPDSI, which better approaches the supplydemand balance

    O desafio da previsão do comportamento fora-do-plano de edifícios existentes de alvenaria

    Get PDF
    O comportamento sísmico de estruturas existentes em alvenaria é muito condicionado pelo seu comportamento fora-do-plano, originando os chamados mecanismos locais, existindo diversas metodologias que tentam prever o comportamento deste tipo de estruturas e/ou modos de colapso. Este trabalho pretende resumir os principais resultados obtidos num evento subordinado ao tema “Methods and challenges on the out-of-plane assessment of existing masonry buildings”, inserido na 9th IMC (2014) em Guimarães, com o objectivo de prever o comportamento de duas estruturas em alvenaria utilizando métodos de análise correntemente utilizados na análise sísmica de estruturas existentes. Relativamente às estruturas estudadas, uma destas era materializada em alvenaria tradicional de pedra de dois panos, sendo a outra construída em alvenaria de tijolo. Estas estruturas foram ensaiadas à escala real na mesa sísmica do LNEC. No final do presente artigo apresentam-se os principais resultados obtidos com as simulações realizadas e sua comparação com o comportamento real das estruturas.The seismic behaviour of existing masonry buildings is governed by the out-of-plane behaviour in the form of the so-called local mechanisms. Despite recent advances within the area, there are several different methodologies to predict the behaviour of these local mechanisms. The article herein submitted aims to present the main results obtained on a workshop entitled “Methods and challenges on the out-of-plane assessment of existing masonry buildings”, within the 9th IMC (2014) held at Guimarães, with the objective of predict the behaviour of masonry structures making use of any available method for the seismic analysis. Regarding the studied structures, one was built on traditional doubleleaf stone masonry while the other was built on brick masonry, and they were tested at LNEC shaking table. The main conclusions are presented at the end of the article, namely the obtained results with the prediction and the observed experimental behavior

    Wear and surface residual stress evolution on twin-disc tests of rail/wheel steels

    Get PDF
    Twin disc tribological tests were performed in wheel and rail materials, with specimens taken from a Spanish AVE train wheel and a UIC60 rail, in a program intended to characterize their contact fatigue behavior. The X-ray diffraction technique was used to characterize the residual stress distribution at the initial and damaged stages, as well as in intermediate stages, since existing residual stresses in the surface layers of the railways steels and its evolution during contact loading can have a major influence on crack initiation and propagation

    Analysis of the influence of pharmacotherapy on the quality of life of seniors with osteoarthritis

    Get PDF
    AbstractAimsThis study aimed to assess the influence of pharmacotherapy on health-related quality of life of elderly with ostheoarthritis.MethodsLongitudinal study involving 91 older adults from both genders (Age: 70.36±5.57 years) from EELO project with self-reported knee or hip ostheoartritis, confirmed by radiographic analysis. Data regarding pharmacotherapy was assessed by a structured questionnaire and the quality of life was analyzed by SF-36 questionnaire at the initial moment and two years thereafter. All domains from quality of life were grouped in physical and mental components for further data analysis.ResultsA statistically significant decline in both physical and mental components of quality of life was observed (Wilcoxon test, p<0.05). However, it was observed a slighted decline in physical components in group treated with chondroitin/glucosamine when compared to other groups, according to Kruskal–Wallis test (p=0.007). On the other hand, it was not observed any influence of pharmacological treatment on mental components of health-related quality of life (p>0.05).ConclusionsTreatment with condroitin/glucosamin contributes to a lower decline in physical component while it had no influence on mental component of health-related quality of life in older adults with ostheoartritis

    Stationary solutions for the parity-even sector of the CPT-even and Lorentz-covariance-violating term of the standard model extension

    Full text link
    In this work, we focus on some properties of the parity-even sector of the CPT-even electrodynamics of the standard model extension. We analyze how the six non-birefringent terms belonging to this sector modify the static and stationary classical solutions of the usual Maxwell theory. We observe that the parity-even terms do not couple the electric and magnetic sectors (at least in the stationary regime). The Green's method is used to obtain solutions for the field strengths E and B at first order in the Lorentz- covariance-violating parameters. Explicit solutions are attained for point-like and spatially extended sources, for which a dipolar expansion is achieved. Finally, it is presented an Earth-based experiment that can lead (in principle) to an upper bound on the anisotropic coefficients as stringent as (κ~e)ij<2.9×1020.(\widetilde{\kappa}_{e-}) ^{ij}<2.9\times10^{-20}.Comment: 8 pages, revtex style, revised published version, to appear in EPJC (2009

    Floral Origin and Physical and Chemical Characteristics of Honey from Africanized Bees in Apiaries of Ubiratã and Nova Aurora, State of Paraná

    Get PDF
    Physical and chemical characteristics of honey may vary due to the diversity of flora and soil characteristics, or seasonal factors. This study was carried out in two counties, Nova Aurora and Ubiratã, located in the West and Center-West regions of the State of Paraná. The objective of the study was to verify if the physical and chemical parameters of Apis mellifera (L.) honey are in accordance with the national standard, as well as to verify how the 21 samples collected in the two localities are grouped, based on the physical, chemical and pollen characteristics. Honey was analyzed for sugar, ash, protein, moisture, color, electrical conductivity, formaldehyde index, diastase and viscosity. Samples of honey containing the dominant pollen types Glycine max (L.) Merr. and Eucalyptus sp. formed groupings similar to those based on physical and chemical characteristics, however, the multivariate classification of honey samples in groups based on pollen types was not an efficient method to group samples of polyfloral honey
    corecore