Browsing by Author "Xavier, J."
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- Detection and tracking of moving objects in an indoor environmentPublication . Xavier, J.; Pacheco, M.; Castro, D.; Ruano, AntonioIn this work we present a method for detection and tracking of moving objects – DATMO using a laser range finder. The ability to track a moving object is one of the most desired capabilities of a robotic system, either for the purpose of surveillance, crowd control or collision avoidance just to mention a few applications. To achieve this objective we use a SICK LMS200 range finder for tracking multiple moving objects in an indoor workspace. The DATMO system is composed by four procedures: data segmentation, feature extraction, classification and tracking of objects.
- Fast line, arc/circle and leg detection from laser scan data in a player driverPublication . Xavier, J.; Pacheco, M.; Castro, D.; Ruano, Antonio; Nunes, U.A feature detection system has been developed for real-time identification of lines, circles and people legs from laser range data. A new method sutable for arc/circle detection is proposed: the Inscribed Angle Variance (IAV). Lines are detected using a recursive line fitting method.
- Phylogenetically and spatially close marine sponges harbour divergent bacterial communitiesPublication . Hardoim, C. C. P.; Esteves, A. I. S.; Pires, F. R.; Gonçalves, J. M. S.; Cox, C. J.; Xavier, J.; da Silva Costa, RodrigoRecent studies have unravelled the diversity of sponge-associated bacteria that may play essential roles in sponge health and metabolism. Nevertheless, our understanding of this microbiota remains limited to a few host species found in restricted geographical localities, and the extent to which the sponge host determines the composition of its own microbiome remains a matter of debate. We address bacterial abundance and diversity of two temperate marine sponges belonging to the Irciniidae family - Sarcotragus spinosulus and Ircinia variabilis – in the Northeast Atlantic. Epifluorescence microscopy revealed that S. spinosulus hosted significantly more prokaryotic cells than I. variabilis and that prokaryotic abundance in both species was about 4 orders of magnitude higher than in seawater. Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) profiles of S. spinosulus and I. variabilis differed markedly from each other – with higher number of ribotypes observed in S. spinosulus – and from those of seawater. Four PCR-DGGE bands, two specific to S. spinosulus, one specific to I. variabilis, and one present in both sponge species, affiliated with an uncultured sponge-specific phylogenetic cluster in the order Acidimicrobiales (Actinobacteria). Two PCR-DGGE bands present exclusively in S. spinosulus fingerprints affiliated with one sponge-specific phylogenetic cluster in the phylum Chloroflexi and with sponge-derived sequences in the order Chromatiales (Gammaproteobacteria), respectively. One Alphaproteobacteria band specific to S. spinosulus was placed in an uncultured sponge-specific phylogenetic cluster with a close relationship to the genus Rhodovulum. Our results confirm the hypothesized host-specific composition of bacterial communities between phylogenetically and spatially close sponge species in the Irciniidae family, with S. spinosulus displaying higher bacterial community diversity and distinctiveness than I. variabilis. These findings suggest a pivotal host-driven effect on the shape of the marine sponge microbiome, bearing implications to our current understanding of the distribution of microbial genetic resources in the marine realm.
- Polar marine biology science in Portugal and Spain: Recent advances and future perspectivesPublication . Xavier, J.; Barbosa, Ana B.; Agustí, S.; Alonso-Sáez, L.; Alvito, P.; Ameneiro, J.; Ávila, C.; Baeta, A.; Canário, J.; Carmona, R.; Catry, P.; Ceia, F.; Clark, M. S.; Cristobo, F. J.; Cruz, B.; Duarte, C. M.; Figuerola, B.; Gili, J.-M.; Gonçalves, A. R.; Gordillo, F. J. L.; Granadeiro, J. P.; Guerreiro, M.; Isla, Enrique; Jiménez, C.; López-González, P. J.; Lourenço, S.; Marques, J. C.; Moreira, E.; Mota, A. M.; Nogueira, M.; Núñez-Pons, L.; Orejas, C.; Paiva, V. H.; Palanques, A.; Pearson, G. A.; Pedrós-Alió, C.; Peña Cantero, T. L.; Power, Deborah; Ramos, J. A.; Rossi, S.; Serrão, EsterPolar marine ecosystems have global ecological and economic importance because of their unique biodiversity and their major role in climate processes and commercial fisheries, among others. Portugal and Spain have been highly active in a wide range of disciplines in marine biology of the Antarctic and the Arctic. The main aim of this paper is to provide a synopsis of some of the results and initiatives undertaken by Portuguese and Spanish polar teams within the field of marine sciences, particularly on benthic and pelagic biodiversity (species diversity and abundance, including microbial, molecular, physiological and chemical mechanisms in polar organisms), conservation and ecology of top predators (particularly penguins, albatrosses and seals), and pollutants and evolution of marine organisms associated with major issues such as climate change, ocean acidification and UV radiation effects. Both countries have focused their polar research more in the Antarctic than in the Arctic. Portugal and Spain should encourage research groups to continue increasing their collaborations with other countries and develop multi-disciplinary research projects, as well as to maintain highly activememberships within major organizations, such as the Scientific Committee for Antarctic Research (SCAR), the International Arctic Science Council (IASC) and the Association of Polar Early Career Scientists (APECS), and in international research projects.