3,968 research outputs found

    Greedy randomized dispatching heuristics for the single machine scheduling problem with quadratic earliness and tardiness penalties

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    In this paper, we present greedy randomized dispatching heuristics for the single machine scheduling problem with quadratic earliness and tardiness costs, and no machine idle time. The several heuristic versions differ, on the one hand, on the strategies involved in the construction of the greedy randomized schedules. On the other hand, these versions also differ on whether they employ only a final improvement step, or perform a local search after each greedy randomized construction. The proposed heuristics were compared with existing procedures, as well as with optimum solutions for some instance sizes. The computational results show that the proposed procedures clearly outperform their underlying dispatching heuristic, and the best of these procedures provide results that are quite close to the optimum. The best of the proposed algorithms is the new recommended heuristic for large instances, as well as a suitable alternative to the best existing procedure for the larger of the middle size instances.scheduling, single machine, early/tardy, quadratic penalties, greedy randomized dispatching rules

    Reestruturação produtiva e condições sociais

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    Este artigo aborda a reestruturação produtiva que marcou o Brasil nos anos 90, analisando os seus efeitos sociais. Reconhecendo como essa reestruturação está associada à inserção do país na dinâmica da economia globalizada e à implementação de um conjunto de políticas recomendadas pelos organismos multilaterais, o texto assinala como as transformações decorrentes dessas políticas vêm se traduzindo em, a) baixos níveis de crescimento econômico; b) uma deterioração das condições de trabalho e renda da maioria da população; c) uma acentuação das desigualdades sociais e espaciais ;e d) uma reorientação profunda e regressiva das políticas e do sistema de proteção social

    Improving order-picking operations with precedence constraints through efficient storage location assignment: evidence from a retail company

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    This paper is inspired by a manual picking retail company where shape and weight constraints affect the order-picking process. We proposed an alternative clustering similarity index that considers the similarity, the weight and the shape of products. This similarity index was further incorporated in a storage allocation heuristic procedure to set the location of the products. We test the procedure in a retail company that supplies over 191 stores, in Northern Portugal. When comparing the strategy currently used in the company with this procedure, we found out that our approach enabled a reduction of up to 40% on the picking distance; a percentage of improvement that is 32% higher than the one achieved by applying the Jaccard index, a similarity index commonly used in the literature. This allows warehouses to save time and work faster.info:eu-repo/semantics/publishedVersio

    Neural Connectivity with Hidden Gaussian Graphical State-Model

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    The noninvasive procedures for neural connectivity are under questioning. Theoretical models sustain that the electromagnetic field registered at external sensors is elicited by currents at neural space. Nevertheless, what we observe at the sensor space is a superposition of projected fields, from the whole gray-matter. This is the reason for a major pitfall of noninvasive Electrophysiology methods: distorted reconstruction of neural activity and its connectivity or leakage. It has been proven that current methods produce incorrect connectomes. Somewhat related to the incorrect connectivity modelling, they disregard either Systems Theory and Bayesian Information Theory. We introduce a new formalism that attains for it, Hidden Gaussian Graphical State-Model (HIGGS). A neural Gaussian Graphical Model (GGM) hidden by the observation equation of Magneto-encephalographic (MEEG) signals. HIGGS is equivalent to a frequency domain Linear State Space Model (LSSM) but with sparse connectivity prior. The mathematical contribution here is the theory for high-dimensional and frequency-domain HIGGS solvers. We demonstrate that HIGGS can attenuate the leakage effect in the most critical case: the distortion EEG signal due to head volume conduction heterogeneities. Its application in EEG is illustrated with retrieved connectivity patterns from human Steady State Visual Evoked Potentials (SSVEP). We provide for the first time confirmatory evidence for noninvasive procedures of neural connectivity: concurrent EEG and Electrocorticography (ECoG) recordings on monkey. Open source packages are freely available online, to reproduce the results presented in this paper and to analyze external MEEG databases

    Multidimensional Health Impact of Multicomponent Exercise and Sustainable Healthy Diet Interventions in the Elderly (MED-E): Study Protocol

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    Data concerning the combined effect of diet and exercise interventions on overall health in the elderly are scarce. The MED-E project's primary aim is to assess the effect of the different 3-month sustainable healthy diet (SHD) and multicomponent training (MT) interventions on several health outcomes in the elderly. A quasi-experimental study assigned older adults into four groups: (1) SHD, (2) MT, (3) SHD + MT, or (4) control group (CG). The SHD intervention included a weekly offer of a mixed food supply and individual and group nutritional sessions on the principles of an SHD. The MT groups were submitted to 50-min exercise sessions three times a week. The primary outcomes were blood biomarkers and metabolic profile alterations that were assessed pre- and post-intervention. Additionally, data on dietary intake and nutritional adequacy, physical fitness, body composition and anthropometry, cognitive function, quality of life, and geographical data were assessed at the same time points. The MED-E project's study protocol and future results will add to knowledge about the importance and beneficial contribution of combined SHD and MT interventions on healthy ageing policies

    Le magmatisme terminal de la chaîne hercynienne : signification géodynamique d'une association magmatique identifiée dans le Carbonifère terminal du Massif Hercynien Central Marocain

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    Na parte oriental do Maciço Hercínico Central de Marrocos afloram alguns filões intercalados em formações do Carbónico superior do Sudeste da bacia de Azrou-Kénifra. Estes filões instalaram-se paralelamente à estratificação e foram deformados por dobramentos associados aos cavalgamentos que controlaram a sedimentação, o que demonstra o seu carácter sintectónico. A sua composição química permitiu distinguir dois tipos de sequências magmáticas sobrepostas nas séries de Tariwalt e Talgarat, respectivamente de idades V3b e Namuriano-V3c, provável. A primeira inclui rochas básicas de carácter transicional e afinidade alcalina, enquanto a segunda possui uma assinatura calco-alcalina. Estas sequências magmáticas apresentam estreitas semelhanças petrográficas e geoquímicas com as que ocorrem em ambientes de margem activa. As assinaturas geoquímicas e a evolução magmática destas rochas são compatíveis com os dados tectono-sedimentares que caracterizam a bacia de Azrou-Kénifra como uma bacia desenvolvida em regime compressivo, integrada num sistema de "avant pays" determinado por sequências de cavalgamentos propagando-se para NW

    Identifying key environmental indicators in the assessment of the proof-of-concept in pigment production from the marine Cyanobacterium cyanobium sp.

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    Cyanobacteria have long attracted market interest as a source of natural compounds such as pigments with proven bioactivity (carotenoid and phycobiliproteins). The cultivation and extraction processes for such compounds have been developed at different levels, from laboratory trials to photobioreactors on a demonstration scale. Based on this experience, it is possible to propose how the different stages of the process can be improved based on environmental performance indicators. The Life Cycle Assessment (LCA) methodology allows to identify the hotspots that represent the greatest environmental impacts and to propose strategies to focus on those stages that can be improved. The general environmental indicators have been identified and the results showed that cyanobacteria cultivation has the greatest influence on environmental impact for all scales considered (from 20 L to 100 m3), which is attributed to the energy requirements. The main changes proposed to reduce the impact should focus on the stages of reactor cleaning, culture medium sterilisation and biomass drying. The implementation of these improvement alternatives can reduce the impact of the production and extraction processes by 85%. This work demonstrates how technological development must go hand in hand with impact assessment to make the best decisions in the overall process.A PhD fellowship [SFRH/BD/136767/2018] for author F.P. was granted by Fundação para a Ciência e Tecnologia (FCT, Portugal) under the auspices of Programa Operacional Capital Humano (POCH), supported by the European Social Fund and Portuguese funds (MECTES). This work was financially co-supported by Galician Competitive Research Group (GRC ED431C 2017/29) and to the Cross-disciplinary Research in Environmental Technologies (CRETUS Research Center, ED431E 2018/01) and by the strategical funding from FCT (UIDB/04423/2020 and UIDP/04423/2020) to CIIMAR and (UIDB/04469/2020) to CEB.info:eu-repo/semantics/publishedVersio

    Desenvolvimento e avaliação das características psicométricas do inventário de avaliação das percepções dos professores acerca das necessidades ao nível da promoção de competências sociais e emocionais

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    The objective of this study was to evaluate the psychometric properties of an assessment instrument on teachers' perceptions regarding the development of socio-emotional skills. Results revealed a consistent four-factor structure (School/teachers' needs for socio-emotional skills promotion; Needs regarding teaching-learning process; Difficulties in dealing with students' socio-emotional deficits, Socio-emotional needs related to teacher's initial training) with internal consistency values above .79. Confirmatory analyses revealed a good fit of the model to the data. Teachers reported having more needs at the school/ teachers conditions for the promotion of social and emotional needs, and less needs at the level of their Teachers' initial training. The instrument also showed to be sensitive in capturing teachers' perception of schooling social and emotional needs in terms of teachers' gender, pedagogic group and school level.O objectivo deste estudo foi avaliar as características psicométricas de um instrumento de avaliação das percepções dos professores acerca das suas necessidades na promoção das competências sociais e emocionais. Os resultados revelaram uma estrutura de quatro factores (Necessidades ao nível da escola/professor, necessidades ao nível do processo de ensino-aprendizagem, Dificuldades em lidar com défices sócio-emocionais dos alunos e Necessidades ao nível da formação inicial), com valores de consistência interna acima de 0,79. As análises confirmatórias revelaram bom ajustamento do modelo aos dados. Os professores revelaram sentir maiores dificuldades ao nível das condições da escola/ professores e menores ao nível da formação inicial. O instrumento revelou-se também sensível às diferenças de percepções em termos do género, grupo pedagógico, e nível de ensino

    Comparação entre os valores de Procalcitonina e Proteína C reactiva em adultos com doença hemato-oncológica

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    Os pacientes com doença hemato-oncológica submetidos a quimioterapia possuem maior propensão para infecções bacterianas. O seu diagnóstico pode ser efectuado recorrendo-se aos marcadores biológicos: procalcitonina (PCT) e proteína C reactiva (PCR). Neste estudo, observaram-se diferenças estatisticamente significativas na concentração de PCT nos diferentes grupos de infecção, o que não se verificou na concentração de PCR. Observou-se ainda uma fraca correlação entre estes marcadores nos grupos de infecção. Apenas os valores de PCT estão directamente relacionados com a gravidade da infecção, evidenciando-o como um bom marcador de diagnóstico, mais eficaz do que a PCR.Patients with hemato-oncological disease undergoing chemotherapy have a higher susceptibility for bacterial infections. The infection’s diagnosis can be performed by resorting to the use of biological markers: procalcitonin (PCT) and C-reactive protein (CRP). In this study, we observed statistically significant differences in the concentration of PCT between the different groups of infection, which were not observed in CRP concentration. There was also a weak correlation between these markers of infection in these groups. Only PCT values are directly related with the severity of infection, making it a good marker for its diagnosis, more effective than the CRP
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