18 research outputs found

    A construção de um sistema de armazenamento de dados no âmbito do sistema GIST98/EUROBUS

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    Tese de Mestrado. Gestão de Empresas. Escola de Gestão do Porto. Universidade do Porto. 200

    Travel time prediction for the planning of mass transit companies: a machine learning approach

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    In this thesis we undertook a study in order to know how travel time prediction can be used in mass transit companies for planning purposes. Two different problems were identified: the definition of travel times (1) for timetables and (2) for bus and driver duties. All these studies assume the existence of data on the actual trips, typically obtained from Automatic Vehicle Location (AVL) systems.The first problem is a well-known problem with several related studies in the literature. Our approach is not analytical. Instead, we have designed and developed a decision support system that uses past data from the same line and representative of the period the timetable will cover. This problem was the least studied.With respect to the second problem, travel time prediction three days ahead, we focused on how much we can increase in accuracy if we predict travel times for the definition of bus and driver duties as near the date as possible, insteadof using the scheduled travel times (STT). The reason for doing this is that, if the increment is important, it is expected to reduce operational costs and/or increase passengers' satisfaction.In this second problem we used machine learning approaches. However, we started by defining a baseline method (in order to evaluate comparatively the results obtained with more sophisticated methods) and an expert based method using the knowledge we had at the time together with the tra±c experts from the STCP company. Then, we tried three different algorithms with reportedgood results in different problems. They were: support vector machines, random forests and projection pursuit regression. For each of these algorithms, exhaustive tests were done in order to tune parameters. Other tests were done using the three focusing tasks: example selection, domain values selection and feature selection. Accuracy was improved using these approaches.The next step was to experiment heterogeneous ensemble approaches in order to ameliorate further the results by comparison with the use of just one model. An extensive survey on ensemble methods for regression was undertaken.Several experiments using the dynamic selection approach were executed. Approaches using ensembles have improved results consistently when compared to the use of just one model.Experiments on the second problem finished by comparing the baseline, the expert based, the best single algorithm (with the respective tuned parameters and focusing tasks), and the ensemble approach, against the use of STT, onvarious routes. Results gave a small advantage in terms of accuracy to the ensemble approach when compared to the expert based method. However, the expert based approach needs less data and is much faster to tune. The actual method used by STCP (the use of STT) was competitive for circular routes. However, this result can be explained, at least partially, by how these routes are controlled. On the rest of the routes tested, it was clearly beaten.We also try to give practical answers in using travel time predictions for the planning of mass transit companies, using the STCP company as study case. The impact of travel time prediction in the business goals, namely clients'satisfaction and operational costs, is not addressed despite it is the natural step forward of this research

    "Fandango": long term adaptation of exotic germplasm to a Portuguese on-farm-conservation and breeding project

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    Climatic change emphasize the importance of biodiversity maintenance, Suggesting that germplasm adapted to organic, low input, or conventional conditions is needed to face future demands. This Study presents: I - The two steps genesis of the synthetic maize population 'Fandango', A) 'NUTICA' creation: in 1975, Miguel Mota and Silas Pego, initiated a new type of polycross method involving 77 yellow elite inbred lines (dent and flint; 20% Portuguese and 80% North American germplasm) from the NUMI programme (NUcleo de melhoramento de Milho, Braga, Portugal). These inbreds were intermated in natural isolation and progenies submitted to intensive selection for both parents during continued cycles; B) From 'NUTICA' to 'Fandango': Tandango' was composed of all the crosses that resulted from a North Carolina Design I matting design (1 male crossed with 5 females) applied to 'NUTICA'. II - The diversity evolution of 'Fandango' under a Participatory Breeding project at the Portuguese Sousa Valley region (VASO) initiated in 1985 by Pego, with CIMMYT support. Morphological, fasciation expression, and yield trials were conducted in Portugal (3 locations, 3 years) and in the USA (4 locations, I year) using seeds obtained from five to seven cycles of mass selection (MS). The selection across cycles wits clone by the breeder (until cycle 5) and farmer (before cycle II in present). ANOVA and regression analysis on the rate of direct response to selection were performed when the assumption of normality was positively confirmed. Otherwise the non parametric Multivariate Adaptive Regression Splines (MARS) was performed. Response to mass selection in lowa showed significant decrease in yield, while in Portugal a significant increase for time of silking, plant and ear height, ear diameters 2, 37 4, kernel number, cot) diameters, and rachis was observed. At this location also a significant decrease was observed for thousand kernel weight and ear length. These results showed that mass selection were not effective for significant yield increase, except when considered Lousada with breeder selection (3.09% of gain per cycle per year). Some non-para metric methods (MARS, decision trees and random forests) were used to get insights on the causes that explain yield in Fandango. Kernel weight and ear weight were the most important traits, although row numbers, number of kernels per row, ear length, and ear diameter were also of some importance influencing 'Fandango' yield

    Association between Elevated Iodine Intake and IQ among School Children in Portugal

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    Funding Information: This project was funded through grants by the Public Health Initiatives Programme (PT06), financed by EEA Grants Financial Mechanism 2009–2014, and supported by FEDER through the operation POCI-01-0145-FEDER-007746 funded by the Programa Operacional Competitividade e Internacionalização—COMPETE2020 and by National Funds through FCT—Fundação para a Ciência e a Tecnologia, I.P., within CINTESIS, R&D Unit (reference UIDP/4255/2020) and within the scope of the project RISE, Associated Laboratory (reference LA/P/0053/2020). DP and VCF also received individual funding from Fundação para a Ciência e a Tecnologia (SFRH/BPD/109158/2015 in the first case; SFRH/BPD/109153/2015, UIDB/50006/2020, UIDP/50006/2020, and LA/P/0008/2020 in the second case).The goal of this work was to examine whether elevated iodine intake was associated with adverse effects on IQ among school-age children in Portugal. In a representative sample of children from the north of the country, IQ percentiles by age (assessed with Raven’s Colored Progressive Matrices) were dichotomized to <50 (“below-average” IQs) and ≥50. Morning urine iodine concentrations, corrected for creatinine, were dichotomized to <250 µg/g and ≥250 µg/g, according to the European Commission/Scientific Committee on Food’s tolerable upper level of daily iodine intake for young children. Data were examined with Chi-square tests, logistic regression, and GLM univariate analysis. The sample (N = 1965) was classified as generally iodine-adequate (median urinary iodine concentration = 129 µg/L; median iodine-to-creatinine ratio = 126 µg/g) according to the WHO’s criteria. A greater proportion of children in the ≥250 µg/g group had below-average IQs, compared to children with less than 250 µg/g (p = 0.037), despite a sizable (though non-significant) proportion of children in the less-than-250 µg/g group also presenting below-average IQs, at the bottom of the iodine distribution (<50 µg/g). The proportion of below-average IQs increased with increasingly elevated iodine concentrations (p = 0.047). The association remained significant after the adjustment for confounders, with the elevated iodine group showing increased odds of having below-average IQs when compared with the non-elevated iodine group (OR 1.55; 95% CI 1.11–2.17; p = 0.011). Consistently, the former group presented a lower mean IQ than the latter (p = 0.006). High iodine intake was associated with lower IQs even in a population classified as iodine-adequate. These results bear on child cognition and on initiatives involving iodine supplementation.publishersversionpublishe

    Uso de drogas e o aumento das infecções sexualmente transmissíveis: uma revisão sistemática: Drug use and the increase in sexually transmitted infections: a systematic review

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    Populações de usuários de drogas têm sido associadas a epidemias de infecções ou Infecções Sexualmente Transmissíveis, especialmente a infecção pelo HIV (que está associada a drogas injetáveis, uso de equipamentos contaminados para drogas injetáveis e sexo inseguro). A droga mais associada às DSTs é a cocaína fumável de base livre (crack), devido ao aumento dos comportamentos sexuais de risco. Diante disso, o presente estudo teve como objetivo compreender o impacto do uso de drogas no aumento das infecções sexualmente transmissíveis. Para isso, adotou-se como metodologia a revisão sistemática de literatura, realizando buscas nas bases de dados Scielo, Pubmed e BVS/Medline a partir do uso de descritores DeCS/MeSH e aplicação de critérios de inclusão e exclusão. A partir da análise e interpretação dos dados, concluiu-se que que pessoas que fazem uso abusivo de drogas lícitas ou ilícitas, sejam elas mulheres, homens, adolescentes, jovens, adultos, idosos, em situação de rua ou não, tendem a desenvolver comportamentos vulneráveis que pode resultar em IST. Somado a isso, enquanto comportamento de risco, tem-se a preferência por não usar preservativo, seja em relações sexuais com pessoas monogâmicas como com dois ou mais parceiros. Nesses casos, tanto o uso exacerbado de drogas como a falta de informação sobre comportamento sexual demonstram-se insuficientes

    Pervasive gaps in Amazonian ecological research

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    Pervasive gaps in Amazonian ecological research

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    Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio

    ATLANTIC EPIPHYTES: a data set of vascular and non-vascular epiphyte plants and lichens from the Atlantic Forest

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    Epiphytes are hyper-diverse and one of the frequently undervalued life forms in plant surveys and biodiversity inventories. Epiphytes of the Atlantic Forest, one of the most endangered ecosystems in the world, have high endemism and radiated recently in the Pliocene. We aimed to (1) compile an extensive Atlantic Forest data set on vascular, non-vascular plants (including hemiepiphytes), and lichen epiphyte species occurrence and abundance; (2) describe the epiphyte distribution in the Atlantic Forest, in order to indicate future sampling efforts. Our work presents the first epiphyte data set with information on abundance and occurrence of epiphyte phorophyte species. All data compiled here come from three main sources provided by the authors: published sources (comprising peer-reviewed articles, books, and theses), unpublished data, and herbarium data. We compiled a data set composed of 2,095 species, from 89,270 holo/hemiepiphyte records, in the Atlantic Forest of Brazil, Argentina, Paraguay, and Uruguay, recorded from 1824 to early 2018. Most of the records were from qualitative data (occurrence only, 88%), well distributed throughout the Atlantic Forest. For quantitative records, the most common sampling method was individual trees (71%), followed by plot sampling (19%), and transect sampling (10%). Angiosperms (81%) were the most frequently registered group, and Bromeliaceae and Orchidaceae were the families with the greatest number of records (27,272 and 21,945, respectively). Ferns and Lycophytes presented fewer records than Angiosperms, and Polypodiaceae were the most recorded family, and more concentrated in the Southern and Southeastern regions. Data on non-vascular plants and lichens were scarce, with a few disjunct records concentrated in the Northeastern region of the Atlantic Forest. For all non-vascular plant records, Lejeuneaceae, a family of liverworts, was the most recorded family. We hope that our effort to organize scattered epiphyte data help advance the knowledge of epiphyte ecology, as well as our understanding of macroecological and biogeographical patterns in the Atlantic Forest. No copyright restrictions are associated with the data set. Please cite this Ecology Data Paper if the data are used in publication and teaching events. © 2019 The Authors. Ecology © 2019 The Ecological Society of Americ

    Pervasive gaps in Amazonian ecological research

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    Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost
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