12,440 research outputs found

    Transposição congenitamente corrigida das grandes artérias e coarctação da aorta: uma associação pouco comum

    Get PDF
    Congenitally corrected transposition of the great arteries, L-TGA, is a rare abnormality accounting for less than 0.5% of clinically apparent congenital heart disease. Age at time of diagnosis and survival rate are variable and depend mostly on associated anomalies. The authors present a clinical case of a twenty-four-year-old woman in whom, in a routine echocardiogram, congenitally corrected transposition of the great arteries and aortic coarctation were diagnosed, an unusual association. They describe the results of complementary exams (echocardiography, chest X-ray, electrocardiogram and cardiac angiography) that they believe to be useful for the correct diagnosis of this clinical situation. Additionally, the authors make a brief review of the literature relevant to the case

    Corrections to the Boltzmann mean free path in disordered systems with finite size scatterers

    Full text link
    The mean free path is an essential characteristic length in disordered systems. In microscopic calculations, it is usually approximated by the classical value of the elastic mean free path. It corresponds to the Boltzmann mean free path when only isotropic scattering is considered, but it is different for anisotropic scattering. In this paper, we work out the corrections to the so called Boltzmann mean free path due to multiple scattering effects on finite size scatterers, in the s-wave approximation, ie. when the elastic mean free path is equivalent to the Boltzmann mean free path. The main result is the expression for the mean free path expanded in powers of the perturbative parameter given by the scatterer density.Comment: 12 page

    Effect of the curing time on the numerical modelling of the behaviour of a chemically stabilised soft soil

    Get PDF
    The ability of the Modified Cam Clay (MCC) model combined with the Von Mises (VM) model, considering the effect of curing time on the enhancement of the mechanical properties of a chemically stabilised soft soil is examined. The evolution of the strength and stiffness over time is based on the results of undrained compressive strength (UCS) tests carried out for different curing times (from 28 days to 360 days). Initially, the MCC/VM models associated with the effect of curing time are validated by CIU triaxial tests, for curing times of 28 and 90 days. Finally, the behaviour of an embankment built on a soft soil reinforced with deep mixing columns is predicted based on the previously validated models. The results show that the increase of curing time of the DMCs slightly decreases the settlement obtained with a curing time of 28 days

    Uso de carvão como filtro para manipueira visando produção de fertilizante de liberação lenta.

    Get PDF
    Os subprodutos resultantes do processamento da mandioca têm sido grandes responsáveis por sérios problemas de contaminação do meio ambiente, poluindo solos e cursos de água doce. A manipueira é o resíduo líquido gerado pela prensagem das raízes nas indústrias de processamento de mandioca. A biomassa carbonizada (biochar) utilizada como filtro para resíduo líquido, a manipueira, possibilita a redução da carga poluente desse resíduo.PDF. 074_11

    Childhood social adversity and clustering of health risk behaviours during early adolescence in a population-based birth cohort

    Get PDF
    Objectives: This study aimed to prospectively explore the association between early lifetime exposure to psychosocial adversity and engagement in health risk behaviours (HRBs) during early adolescence. Study design: This was a prospective study. Methods: This study used data from the baseline (2005-2006), third (2016-2017) and fourth waves (2018-2020) of the Generation XXI birth cohort. Socio-economic circumstances (SECs) at baseline, adverse childhood experiences (ACEs; e.g. abuse, neglect, household dysfunction) at age 10 years and HRBs (i.e. alcohol consumption, smoking, physical exercise level, sedentary behaviours, sleep duration and eating behaviours) at age 13 years were measured. Patterns of HRBs were obtained using latent class analysis. Latent class regression analysis was used to estimate the likelihood of being engaged in HRBs according to the extent of exposure to ACEs (i.e. 0 ACEs, 1-3 ACEs, 4-5 ACEs and & GE;6 ACEs) and negative family SECs. Results: Adolescents whose mothers had a low level of education (adjusted odds ratio [aOR] = 2.72 [95% confidence interval {CI}, 2.33-3.18]), low occupational status (aOR = 3.21 [95% CI, 2.68-3.85]) and low income (aOR = 2.70 [95% CI, 2.23-3.28]) were more likely to be engaged in HRBs than their peers with higher SECs. Adolescents who experienced more ACEs were at a significantly increased risk of involve-ment in HRBs (aOR = 1.86 [95% CI, 1.33-2.63] for 4-5 ACEs vs aOR 2.41 [95% CI, 1.72-3.43] for & GE;6 ACEs). No significant gender differences were observed. Conclusions: Adolescents from families with low SECs were more likely than their more affluent coun-terparts to be engaged in HRBs. Furthermore, more ACEs contributed to widening health inequalities. & COPY; 2023 The Author(s). Published by Elsevier Ltd on behalf of The Royal Society for Public Health. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).This work was supported by the European Regional Development Fund through the Operational Programme Competitiveness and Internationalization and national funding from the Foundation for Science and Technology (FCT) , Portuguese Ministry of Science, Technology, and Higher Education under the projects HIneC: When do health inequalities start? Understanding the impact of childhood social adversity on health trajectories from birth to early adolescence (POCI-01-0145-FEDER-029567; reference: PTDC/SAU-PUB/29567/2017) . It is also supported by Unidade de Investigacao em Epidemiologia-Instituto de Saude Publica da Universidade do Porto (EPIUnit) (UIDB/04750/2020) , Laboratorio para a Investigacao Integrativa e Translacional (ITR) , Porto, Portugal (LA/P/0064/2020) , PhD grant SFRH/BD/144503/2019 (to A.A.) funded by FCT through Fundo Social Europeu, and FCT Investigator contract CEECIND/01516/2017 (to S.F.)

    Ab-initio study of the relation between electric polarization and electric field gradients in ferroelectrics

    Full text link
    The hyperfine interaction between the quadrupole moment of atomic nuclei and the electric field gradient (EFG) provides information on the electronic charge distribution close to a given atomic site. In ferroelectric materials, the loss of inversion symmetry of the electronic charge distribution is necessary for the appearance of the electric polarization. We present first-principles density functional theory calculations of ferroelectrics such as BaTiO3, KNbO3, PbTiO3 and other oxides with perovskite structures, by focusing on both EFG tensors and polarization. We analyze the EFG tensor properties such as orientation and correlation between components and their link with electric polarization. This work supports previous studies of ferroelectric materials where a relation between EFG tensors and polarization was observed, which may be exploited to study ferroelectric order when standard techniques to measure polarization are not easily applied.Comment: 9 pages, 6 figures, 5 tables, corrected typos, as published in Phys. Rev.

    Dynamical stability analysis of the HD202206 system and constraints to the planetary orbits

    Full text link
    Long-term precise Doppler measurements with the CORALIE spectrograph revealed the presence of two massive companions to the solar-type star HD202206. Although the three-body fit of the system is unstable, it was shown that a 5:1 mean motion resonance exists close to the best fit, where the system is stable. We present here an extensive dynamical study of the HD202206 system aiming at constraining the inclinations of the two known companions, from which we derive possible ranges of value for the companion masses. We study the long term stability of the system in a small neighborhood of the best fit using Laskar's frequency map analysis. We also introduce a numerical method based on frequency analysis to determine the center of libration mode inside a mean motion resonance. We find that acceptable coplanar configurations are limited to inclinations to the line of sight between 30 and 90 degrees. This limits the masses of both companions to roughly twice the minimum. Non coplanar configurations are possible for a wide range of mutual inclinations from 0 to 90 degrees, although ΔΩ=0[π]\Delta\Omega = 0 [\pi] configurations seem to be favored. We also confirm the 5:1 mean motion resonance to be most likely. In the coplanar edge-on case, we provide a very good stable solution in the resonance, whose χ2\chi^2 does not differ significantly from the best fit. Using our method to determine the center of libration, we further refine this solution to obtain an orbit with a very low amplitude of libration, as we expect dissipative effects to have dampened the libration.Comment: 14 pages, 18 figure

    Study of the processing and properties of mixtures of recycled plastics for outdoor applications

    Get PDF
    There is an industrial need for the study of the mechanical and physical properties of recycled polyolefins mixed with cellulose fibres from diapers, wood and packaging containing aluminium. The recycling of thermoplastic based residues is economically very interesting for the easy reprocessing of these materials and flexible shaping using conventional moulding processes as injection moulding or intrusion. Various mixtures of these materials were characterized in terms of their constituents and properties determined using 200 mm square mouldings of 10 mm and 5 mm thickness, in view of their potential application in urban furniture. These mouldings were processed by injection moulding and by intrusion that is a method which uses and extruder for delivering the melt directly into an injection mould. The mouldings were tested in terms of theirmechanical performance in impact and flexion. The intrusion process yielded mouldings with properties similar to injection moulding but appeared to be more attractive for requiring lower moulding pressure and thus lighter and cheaper tooling. The morphology of the mouldings, observed by bright field light microscopy showed some contamination and voiding associated to specific processing conditions and moulding size, the thinner mouldings having less voids than the 10 mm thick. The higher voiding in the thicker mouldings was detrimental to the flexural and impact performances of the parts. The coefficient of linear thermal expansion was determined and showed to be sensitive to the percentage of LDPE and fibres in the mixtures. The flexural stiffness of the moulded plates was assessed using the whole mouldings in the 3-point support test and showed the positive influence of the wood fibres and the diaper content in the mixtures. Conversely the impact performance assessed by the Charpy test was affected by the diaper content, but benefitted from the presence of aluminium from the recycled packaging. The prediction of these properties using the law of mixtures for predicting the overall density in the mouldings was not particularly accurate for the mixtures with recycled diapers.European Commission for Education and Training, Erasmus placement scholarship at Hogeschool Gen
    • …
    corecore