397 research outputs found
Climate trends and behaviour of drought indices based on precipitation and evapotranspiration in Portugal
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
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
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The Impact of Sugar Cane–Burning Emissions on the Respiratory System of Children and the Elderly
We analyzed the influence of emissions from burning sugar cane on the respiratory system during almost 1 year in the city of Piracicaba in southeast Brazil. From April 1997 through March 1998, samples of inhalable particles were collected, separated into fine and coarse particulate mode, and analyzed for black carbon and tracer elements. At the same time, we examined daily records of children ( 64 years of age) admitted to the hospital because of respiratory diseases. Generalized linear models were adopted with natural cubic splines to control for season and linear terms to control for weather. Analyses were carried out for the entire period, as well as for burning and nonburning periods. Additional models were built using three factors obtained from factor analysis instead of particles or tracer elements. Increases of 10.2 μg/m3 in particles ≥ 2.5 μm/m3 aerodynamic diameter (PM2.5) and 42.9 μg/m3 in PM10 were associated with increases of 21.4% [95% confidence interval (CI), 4.3–38.5] and 31.03% (95% CI, 1.25–60.21) in child and elderly respiratory hospital admissions, respectively. When we compared periods, the effects during the burning period were much higher than the effects during nonburning period. Elements generated from sugar cane burning (factor 1) were those most associated with both child and elderly respiratory admissions. Our results show the adverse impact of sugar cane burning emissions on the health of the population, reinforcing the need for public efforts to reduce and eventually eliminate this source of air pollution
Wear and surface residual stress evolution on twin-disc tests of rail/wheel steels
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
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
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
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
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
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