Hedonic methodologies in the real estate valuation

Comunicação apresentada no MME2010, que decorreu de 21 a 24 de Outubro de 2010, em Cimbra.Several models have been used to estimate the market value of real estate properties, with the aim of obtaining better measures of the price of transaction than the official figures calculated for fiscal purposes. Hedonic models are well known techniques for estimating values of complex goods, as a house. Here they are focused on flats and apartments sold between 2005 and 2009 in a medium size portuguese city; sample data have been collected in collaboration with real estate agents, both for new and non-new houses, using transaction prices. Several internal and external characteristics of each property are included in the models, and the methodology can be extended to other cities alike in the country.Foundation for Science and Tecnolog

Variáveis explicativas e a sua importância na formação do preço de um apartamento em Portugal: uma abordagem com redes neuronais artificiais

Conhecer o preço da habitação com objectividade, através da medida das suas características é um assunto que ocupa diversos investigadores. A selecção das variáveis explicativas foi validade através dos testes de diagnóstico usuais na modelação econométrica. Este estudo descreve uma investigação sobre a estimação de uma rede neuronal artificial, para o preço de venda de um apartamento numa cidade Portuguesa. Apresentam-se os resultados obtidos na estimação de várias redes neuronais artificiais, em relação ao erro relativo do conjunto de teste, com três tipos de partições de dados diferentes. A partição que funcionou melhor foi a 90% vs 10%, respectivamente para o conjunto de aprendizagem e de teste. Também foi analisada a possibilidade da ordem de importância das variáveis explicativas do preço, estar dependente do tipo de partição utilizada, tendo-se concluído que a área útil, é sempre a variável explicativa que surge com maior importância, independentemente do tipo de partição utilizada

Proposal of a lightweight, offline, full-text search engine for an mHealth app

A patients ability to recall and retrieve health information contributes to a better health management. HealthTalks was developed to address these issues by recording a summary of a medical appointment, uttered by the physician, and transcribing it. For each appointment, the user can also take free-text notes. Nowadays, search engines have become a ubiquitous part of everyones life and are expected on most applications. Here, we describe the development of a search engine for HealthTalks. The apps characteristics demand a lightweight and offline engine, which requires a specific solution rather than an existing library or service. Our approach combines SQLites Full-Text Search 4 module, which includes n-gram indexing, with traditional information retrieval techniques to rank the documents. We created a test collection with summaries of clinical appointments (our documents), information needs, search queries, and relevance assessments for an initial search engine evaluation. Using this test collection, we assessed performance using NDCG@10, the first rank position of a totally relevant result, and query latency. Results are promising, with an average NDCG of 0.97. The median rank position of the first relevant result varies between 1.9 and 1.95, depending on the use of 4-gram character tokenization, an aspect that did not significantly affect the results. We expect this work to be useful for future developments of full-text search engines in mobile environments

Dispersal and coexistence of two non-native crayfish species (Pacifastacus leniusculus and Procambarus clarkii ) in NE Portugal over a 10-year period

NE Portugal is one of the most isolated and low populated regions of Western Europe. Recently, two American crayfish species reached this area: signal crayfish Pacifastacus leniusculus coming from Spain and red swamp crayfish Procambarus clarkii in its northward expansion. The dispersion of both species was followed throughout the last decade in river Maçãs (Douro catchment). Our results support the hypothesis of faster downstream colonisation. The mean spread rate of signal crayfish was faster for the downstream expansion, 2.8 km·yr-1, while the upstream rate was 1.7 km·yr-1. Exceptionally, in one period, the rate of spread reached 6.7 km·yr-1, which was apparently caused by downstream washing in extreme conditions of flow. The mean rate of spread is higher than the observed in other studies which may also be related to the low current velocity of late spring and summer that provides favourable conditions for a fast upstream colonisation. Coexistence of signal and red swamp crayfish was detected in a large river sector. Signal crayfish strongly dominates in the upper and intermediate sectors which are the colder part of the river and in the lower sectors, species abundances are not significantly different. Winter temperature in the higher altitude reaches seems to moderate the competitive abilities of P. clarkii

Coexistência de duas espécies exóticas de lagostins (Pacifastacus leniusculus e Procambarus clarkii) na bacia hidrográfica do rio Sabor (NE Portugal)

Em Portugal existia uma única espécie europeia de lagostim de água doce, Austropotamobius pallipes, o lagostim-de-patas-brancas, que se considera actualmente extinta no país. No nordeste de Portugal continental onde anteriormente ocorria esta espécie, os cursos de água estão actualmente a ser colonizados por duas espécies de lagostins norte americanos. Na década de 70, proveniente de Espanha onde foi intencionalmente introduzido, o lagostim-vermelho-da-Luisiana, Procambarus clarkii, colonizou rapidamente os rios do sul de Portugal, propagando-se depois por todas as massas hídricas do país. Em 1994, as autoridades espanholas introduziram uma outra espécie, o lagostim sinal, Pacifastacus leniusculus, na província de Zamora, que foi detectada em Portugal, no rio Maçãs (Bacia do Sabor) três anos depois. A propagação e evolução das populações destas espécies no rio Maçãs têm sido seguidas anualmente desde 2000. P. clarkii, espécie sub-tropical, nunca atingiu neste curso abundâncias muito elevados. Pelo contrário, P. leniusculus, espécie de águas mais frias, apresenta valores mais elevados, cerca de seis vezes superiores aos de P.clarkii. O lagostim sinal encontra-se bem adaptado, continuando a sua expansão neste rio e prevendo-se que venha a colonizar outras massas hídricas adjacentes. A expansão do lagostim vermelho de jusante para montante parece ser menos efectiva, não tendo, desde 2005, sido observado em novos locais deste rio. A coexistência das duas espécies verifica-se actualmente num troço fluvial de cerca de 45 km de extensão, apesar das diferenças notórias ao nível das características dos seus habitats

A rapide method for separation of adults in a mixed population of Steinernema carpocapsae (Nematoda : Steinernematidae)

La sélection d'un grand nombre de nématodes viables est une condition impérative pour les études sur la physiologie de #Steinernema carpocapsae$. Est décrite ici une méthode rapide et pratique permettant la séparation des mâles et des femelles de ce nématode à partir d'une suspension contenant une population brute. Pour l'utilisation de cette méthode, la densité des mâles et des femelles est déterminée par application de la loi de Stokes modifiée. Les adultes sont séparés dans un gradient discontinu de saccharose s'étageant de 10 et 20%. Quatre-vingt quinze pour cent des mâles et des femelles isolés grâce à cette méthode restent viables. (Résumé d'auteur

A ten years analysis of cork oak (Quercus suber L.) afforestation projects in the Mediterranean region of centre-eastern of Portugal

Portuguese forest area has a great expression being around 39%. Since the last centuries the Quercus suber L.(cork oak) areas have increased, reaching to 715 922 ha (23%) according to the last National forest inventory. Afforestation programmes financed by the European Union and the existing protection laws for the species are one of the main reasons for this increase. These efforts are important to promote for these stands a distribution by age class that ensure cork oak forest sustainability (only 14% of the existing even-aged stands are young stands with less than 10 years). In this study, the programme – Afforestation of Agricultural Land – in the region of Beira Interior Sul was analysed, to assess afforestation success during the period of 2001 to 2011

Colonization and dispersal rates of two non-native crayfish species (Pacifastacus leniusculus and Procambarus clarkii) in NE Portugal

In Europe, a generalized regression of the native crayfish was observed during the past decades. Simultaneously, several non-native species spread in most countries. In Portugal, the red swamp crayfish, Procambarus clarkii, is now occurring in most inland waters. The NE Portugal is one of the most isolated and low populated regions of Western Europe. Most rivers in these region present low levels of human impact and some are actually pristine. Recently, two American crayfish species reached the area: signal crayfish (Pacfastacus leniusculus) coming from Spain and red swamp crayfish. The isolation and the natural conditions of these rivers make them particularly valuable for the study of crayfish colonization and spreading. The colonization by both species was followed throughout the last decade in the Maçãs river (Douro catchment). Sampling was undertaken every year with baited traps. The average dispersal rate of signal crayfish was approximately 2 km/year, although a great variability among sectors was observed. Coexistence of signal and red swamp crayfish was detected in a large part of the river system. Signal crayfish developed well adapted and persistent populations. The lower abundance of red swamp crayfish is apparently caused by the low winter temperatures

Movement and interaction of two exotic crayfish (Pacifastacus leniusculus and Procambarus clarkii) using PIT telemetry in experimental conditions

The coexistence of two exotic crayfish species (Procambarus clarkii and Pacifastacus leniusculus) was observed in a stretch of Rio Maçãs (Douro basin, Northeast of Portugal). The red swamp crayfish, P. clarkii, a sub-tropical species, was first detected in 1979 in Rio Caia (Alentejo) and from there rapidly spread through most freshwater bodies. This species is extremely resistant to severe climatic conditions, living in such contrasting environments as South or Northeast streams of Portugal. The signal crayfish, Pacifastacus leniusculus, a cold-water crayfish recently reached Portuguese waters and is now spreading in Rio Maçãs. To characterise movements, activity patterns and interactions of both species an experiment was developed in a confined area using PIT telemetry equipment with a multi-point decoder unit connected to eight circular panel antennae. Data were collected from sympatric tagged populations monitored during several days, to detect interactions between individuals during night and day

Redes Neuronais Artificiais para estimar o preço da habitação em Portugal

O encontro integrou o 7.º Workshop da APDR sobre o tema "Fronteiras e Desenvolvimento Regional" a ainda a XXXVI Reunion de Estudios Regionales.Neste artigo, foi desenvolvido um modelo de Redes Neuronais Artificiais para estimar o preço de venda de um apartamento. Recorrendo à boa vontade de alguns Agentes Imobiliários, constitui-se uma base de dados com mais de trinta atributos, de apartamentos vendidos entre 2005 e 2009, numa cidade de Portugal. O agrupamento de alguns destes atributos, possibilitou a construção de índices de localização, de conforto, de anexos e de conservação que para além de ter a vantagem de incorporar várias características, reduz significativamente o número de variáveis explicativas no modelo. As variáveis explicativas utilizadas neste modelo, podem facilmente ser generalizadas para outras cidades do país. A utilização das Redes Neuronais Artificias, para estimar o preço da habitação, pode ser bastante útil em Portugal, e é uma séria alternativa aos métodos econométricos