4,746 research outputs found

    Comment on the Adiabatic Condition

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    The experimental observation of effects due to Berry's phase in quantum systems is certainly one of the most impressive demonstrations of the correctness of the superposition principle in quantum mechanics. Since Berry's original paper in 1984, the spin 1/2 coupled with rotating external magnetic field has been one of the most studied models where those phases appear. We also consider a special case of this soluble model. A detailed analysis of the coupled differential equations and comparison with exact results teach us why the usual procedure (of neglecting nondiagonal terms) is mathematically sound.Comment: 9 page

    H.264/AVC to HEVC Video Transcoder Based on Dynamic Thresholding and Content Modeling

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    Femtoscopic correlations and the ΛcN\Lambda_c N interaction

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    We study the prospects for deducing constraints on the interaction of charmed baryons with nucleons from measurements of two-particle momentum correlation functions for Λcp\Lambda_c p. The correlation functions are calculated for ΛcN\Lambda_c N and ΣcN\Sigma_c N interactions that have been extrapolated from lattice QCD simulations at unphysical masses of mπ=410−570m_\pi=410-570 MeV to the physical point using chiral effective field theory as guideline. In addition, we consider phenomenological YcNY_c N models from the literature to explore the sensitivity of the results to the properties of the interaction in detail. We find that a measurement of the Λcp\Lambda_c p correlation functions could indeed allow one to discriminate between strongly attractive ΛcN\Lambda_c N forces, as predicted by some phenomenological models, and a weakly attractive interaction as suggested by the presently available lattice simulations.Comment: 8 pages, 4 figure

    Neonatal Morbi-Mortality in Very Low Birth Weight in Europe: the Portuguese Experience

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    The aim of this study was to access evolution in care of very low birth weight (VLBW) infants after the implementation of a regionalization policy in Portugal. The data of the National Portuguese Network of VLBW infants are analyzed concerning mortality, morbidity, and quality of regionalization. A total of 12,826 VLBW infants born from 1 January 1994 to 31 December 2008 were enrolled, with a prevalence of 0.66%-0.99% of all live born. The global mortality was 11%. The major improvement in survival is in the babies more than 1000 g. Since 2004, the threshold of viability is 25 weeks, but the intact survival is around 28 weeks. In the last 10 years with more efficient regionalization more VLBW babies are born in the right place. The improvement in neonatal mortality rate was determinant in the good evolution of perinatal and infant mortalities. After reinforcement of regionalization policies, we found improvements in mortality for VLBW infants. The aims of regionalization were achieved. The reform of perinatal care in Portugal is an example of how a good diagnosis and adequate proposals combined with a strong political will is crucial for changing.info:eu-repo/semantics/publishedVersio

    Beyond spatial scalability limitations with a massively parallel method for linear oscillatory problems

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    This is the author accepted manuscript. The final version is available from SAGE Publications via the DOI in this record.This paper presents, discusses and analyses a massively parallel-in-time solver for linear oscillatory PDEs, which is a key numerical component for evolving weather, ocean, climate and seismic models. The time parallelization in this solver allows us to significantly exceed the computing resources used by parallelization-in-space methods and results in a correspondingly significantly reduced wall-clock time. One of the major difficulties of achieving Exascale performance for weather prediction is that the strong scaling limit – the parallel performance for a fixed problem size with an increasing number of processors – saturates. A main avenue to circumvent this problem is to introduce new numerical techniques that take advantage of time parallelism. In this paper we use a time-parallel approximation that retains the frequency information of oscillatory problems. This approximation is based on (a) reformulating the original problem into a large set of independent terms and (b) solving each of these terms independently of each other which can now be accomplished on a large number of HPC resources. Our results are conducted on up to 3586 cores for problem sizes with the parallelization-in-space scalability limited already on a single node. We gain significant reductions in the time-to-solution of 118.3 for spectral methods and 1503.0 for finite-difference methods with the parallelizationin-time approach. A developed and calibrated performance model gives the scalability limitations a-priory for this new approach and allows us to extrapolate the performance method towards large-scale system. This work has the potential to contribute as a basic building block of parallelization-in-time approaches, with possible major implications in applied areas modelling oscillatory dominated problems.The authors gratefully acknowledge the Gauss Centre for Supercomputing e.V. (www.gauss-centre.eu) for funding this project by providing computing time on the GCS Supercomputer SuperMUC at Leibniz Supercomputing Centre (LRZ, www.lrz. de). We also acknowledge use of Hartree Centre resources in this work on which the early evaluation of the parallelization concepts were done

    Caracterização parcial e avaliação da maturidade de composto e biofertilizante para a aplicação em áreas de produção orgânica.

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    Este trabalho teve por objetivo acompanhar o desenvolvimento e a determinação da maturidade de compostos e biofertilizantes

    Potential of Graphene–Polymer composites for ligament and tendon repair: a review

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    Tendon/ligament injuries are debilitating conditions that affect the life quality of a great percentage of the adult population. Several challenges still have to be addressed regarding the repair of these tissues, as current treatments show limited success. The use of biocompatible and biodegradable polymeric scaffolds potentially helps accomplish a complete and long-term functional repair but, unfortunately, these materials lack adequate mechanical properties to be used in such demanding applications. Graphene is a subject of interest for tissue-repair applications due to its electrical conductivity and mechanical properties. If incorporated adequately, it may significantly improve the physical properties of the composite, even at small loadings. Furthermore, graphene presents a biocompatible surface that may enhance cell adhesion, proliferation and differentiation and demonstrates promising outcomes in several in vitro and in vivo biological applications. Therefore, herein, the potential of graphene materials for the reinforcement of biodegradable polymers of interest for tendon/ligament repair is explored. The effect of graphene on relevant features such as mechanical properties, biodegradability, and biocompatibility is revised, to understand the feasibility of these composites to fulfill the requirements associated with these tissues and conclude how their applicability is extended to this field.Portuguese Foundation for Science and Technology (FCT) through the National Funds References UIDB/05256/2020 e UIDP/05256/2020. REQUIMTE-LAQV acknowledges the support of the Portuguese Foundation for Science and Technology (FCT) through the National Funds Reference UIDB/50006/2020. Tânia Peixoto also acknowledges the financial support from FCT, through the PhD Grant PD/BD/143035/201

    Carbono das frações orgânicas como indicador de uso de cambissolos e latossolos no estado do Rio de Janeiro.

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    Os solos apresentam resposta diferenciada quanto ao manejo, e o conhecimento mais detalhado de aspectos pedológicos pode auxiliar na interpretação dos resultados obtidos com o uso de indicadores clássicos da matéria orgânica do solo (MOS). Amostras de terra na profundidade de 0-10 cm de Cambissolos (n=42) e de Latossolos (n=32) coletadas sob diferentes usos (mata, mata inicial, pasto, cultivos perenes e cultivos anuais) de uma Microbacia do Estado Rio de Janeiro tiveram sua matéria orgânica fisicamente fracionada. Foi observado que o uso do solo impacta negativamente os teores de carbono total e das frações lábeis e recalcitrantes da MOS, porém de forma diferenciada em relação às classes de solos estudadas. O uso agropecuário propicia redução da MOS em maior proporção na classe dos Cambissolos em relação aos Latossolos. A separação dos Latossolos pelo tipo de horizonte A podem alterar a interpretação dos resultados do impacto do uso

    Farmer and scientific knowledge of soil quality: a social ecological soil systems approach.

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    This article focuses on how farmers identify and evaluate the quality of soils cultivated and how their indicators compare to those used by agricultural scientists. The aim is to bridge the gap between specific farmer knowledge and universal scientific knowledge by adopting an ecosystem framework applied to agriculture through the concept of agro-ecosystems. This approach was applied to farming in mountainous areas of the Brazilian Atlantic Forest, a global environmental hotspot that has been degraded over time. In order to reverse this trend, local actors have to build agro-ecological systems that maintain environmental quality, agronomic sustainability and socio-economic viability. For this to happen, local and scientific knowledge must be bridged and mutually adapted in order to be successful. This study therefore concentrates on processes of inter-communication between farmers and agricultural scientists concerning the role of soil quality in farming and conservation
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