Browsing by Issue Date, starting with "2013-09"
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- Excitability and optical pulse generation in semiconductor lasers driven by resonant tunneling diode photo-detectorsPublication . Romeira, Bruno; Javaloyes, Julien; Ironside, James; Figueiredo, José; Balle, Salvador; Piro, OresteWe demonstrate, experimentally and theoretically, excitable nanosecond optical pulses in optoelectronic integrated circuits operating at telecommunication wavelengths (1550 nm) comprising a nanoscale double barrier quantum well resonant tunneling diode (RTD) photo-detector driving a laser diode (LD). When perturbed either electrically or optically by an input signal above a certain threshold, the optoelectronic circuit generates short electrical and optical excitable pulses mimicking the spiking behavior of biological neurons. Interestingly, the asymmetric nonlinear characteristic of the RTD-LD allows for two different regimes where one obtain either single pulses or a burst of multiple pulses. The high-speed excitable response capabilities are promising for neurally inspired information applications in photonics. (C) 2013 Optical Society of America
- Behavioural responses of sardines Sardina pilchardus to simulated purse-seine capture and slippingPublication . Marçalo, A.; Pousão-Ferreira, P.; Pierce, G. J.; Stratoudakis, Y.; Erzini, KarimThe behavioural effects of confinement of sardine Sardina pilchardus in a purse seine were evaluated through three laboratory experiments simulating the final stages of purse seining; the process of slipping (deliberately allowing fishes to escape) and subsequent exposure to potential predators. Effects of holding time (the time S. pilchardus were held or entangled in the simulation apparatus) and S. pilchardus density were investigated. Experiment 1 compared the effect of a mild fishing stressor (20min in the net and low S. pilchardus density) with a control (fishing not simulated) while the second and third experiments compared the mild stressor with a severe stressor (40min in the net and high S. pilchardus density). In all cases, sea bass Dicentrarchus labrax were used as potential predators. Results indicated a significant effect of crowding time and density on the survival and behaviour of slipped S. pilchardus. After simulated fishing, S. pilchardus showed significant behavioural changes including lower swimming speed, closer approaches to predators and higher nearest-neighbour distances (wider school area) than controls, regardless of stressor severity. These results suggest that, in addition to the delayed and unobserved mortality caused by factors related to fishing operations, slipped pelagic fishes can suffer behavioural impairments that may increase vulnerability to predation. Possible sub-lethal effects of behavioural impairment on fitness are discussed, with suggestions on how stock assessment might be modified to account for both unobserved mortality and sub-lethal effects, and possible approaches to provide better estimates of unobserved mortality in the field are provided. (C) 2013 The Fisheries Society of the British Isles
- Fast cortical keypoints for real-time object recognitionPublication . Terzic, Kasim; Rodrigues, J. M. F.; du Buf, J. M. H.Best-performing object recognition algorithms employ a large number features extracted on a dense grid, so they are too slow for real-time and active vision. In this paper we present a fast cortical keypoint detector for extracting meaningful points from images. It is competitive with state-of-the-art detectors and particularly well-suited for tasks such as object recognition. We show that by using these points we can achieve state-of-the-art categorization results in a fraction of the time required by competing algorithms.
- Molecular richness and biotechnological potential of bacteria cultured from Irciniidae sponges in the north-east AtlanticPublication . Esteves, Ana; Hardoim, Cristiane; Xavier, Joana R.; Gonçalves, Jorge Manuel Santos; Costa, RodrigoSeveral bioactive compounds originally isolated from marine sponges have been later ascribed or suggested to be synthesized by their symbionts. The cultivation of sponge-associated bacteria provides one possible route to the discovery of these metabolites. Here, we determine the bacterial richness cultured from two irciniid sponge species, Sarcotragus spinosulus and Ircinia variabilis, and ascertain their biotechnological potential. A total of 279 isolates were identified from 13 sponge specimens. These were classified into 17 genera - with Pseudovibrio, Ruegeria and Vibrio as the most dominant - and 3 to 10 putatively new bacterial species. While 16S rRNA gene sequencing identified 29 bacterial phylotypes at the 'species' level (97% sequence similarity), whole-genome BOX-PCR fingerprinting uncovered 155 genotypes, unveiling patterns of specimen-dependent occurrence of prevailing bacterial genomes across sponge individuals. Among the BOX-PCR genotypes recovered, 34% were active against clinically relevant strains, with Vibrio isolates producing the most active antagonistic effect. Several Pseudovibrio genotypes showed the presence of polyketide synthase (PKS) genes, and these were for the first time detected in isolates of the genus Aquimarina (Bacteroidetes). Our results highlight great biotechnological potential and interest for the Irciniidae sponge family and their diversified bacterial genomes.
- Sturgeon osteocalcin shares structural features with matrix gla protein evolutionary relationship and functional implicationsPublication . S B Viegas, Carla; Simes, Dina; Williamson, Matthew K.; Cavaco, Sofia; Laizé, Vincent; Price, Paul A.; Leonor Cancela, M.Osteocalcin (OC) and matrix Gla protein (MGP) are considered evolutionarily related because they share key structural features, although they have been described to exert different functions. In this work, we report the identification and characterization of both OC and MGP from the Adriatic sturgeon, a ray-finned fish characterized by a slow evolution and the retention of many ancestral features. Sturgeon MGP shows a primary structure, post-translation modifications, and patterns of mRNA/protein distribution and accumulation typical of known MGPs, and it contains seven possible Gla residues that would make the sturgeon protein the most gamma-carboxylated among known MGPs. In contrast, sturgeon OC was found to present a hybrid structure. Indeed, although exhibiting protein domains typical of known OCs, it also contains structural features usually found in MGPs (e. g. a putative phosphorylated propeptide). Moreover, patterns of OC gene expression and protein accumulation overlap with those reported for MGP; OC was detected in bone cells and mineralized structures but also in soft and cartilaginous tissues. We propose that, in a context of a reduced rate of evolution, sturgeon OC has retained structural features of the ancestral protein that emerged millions of years ago from the duplication of an ancient MGP gene and may exhibit intermediate functional features.
- TOX3 mutations in breast cancerPublication . Jones, James Owain; Chin, Suet-Feung; Wong-Taylor, Li-An; Leaford, Donna; Ponder, Bruce A. J.; Caldas, Carlos; Maia, Ana TeresaTOX3 maps to 16q12, a region commonly lost in breast cancers and recently implicated in the risk of developing breast cancer. However, not much is known of the role of TOX3 itself in breast cancer biology. This is the first study to determine the importance of TOX3 mutations in breast cancers. We screened TOX3 for mutations in 133 breast tumours and identified four mutations (three missense, one in-frame deletion of 30 base pairs) in six primary tumours, corresponding to an overall mutation frequency of 4.5%. One potentially deleterious missense mutation in exon 3 (Leu129Phe) was identified in one tumour (genomic DNA and cDNA). Whilst copy number changes of 16q12 are common in breast cancer, our data show that mutations of TOX3 are present at low frequency in tumours. Our results support that TOX3 should be further investigated to elucidate its role in breast cancer biology.
- Um estudo exploratório sobre o potencial do Data Envelopment Analysis para avaliar a equidade de acesso em cuidados de saúde primáriosPublication . Ribeiro, A. R. F.; Amado, Carla; Santos, Sérgio Pereira dosThis article focuses on the assessment of equity of access to primary health care in Portugal and has three specific objectives: (1) to present a conceptual model for performance evaluation in primary health care, (2) to evaluate the equity of access in a sample of Portuguese health centers groupings (ACES), (3) to analyze the relationship between the level of equity of access and other variables theoretically related to equity of access in primary care. We use the technique Data Envelopment Analysis to compare equity of access. The level of equity of access across the ACES compared varies between 56% and 100% with an average of 82%. Seven ACES (17% of the total) have a relative level of 100% of equity of access. These results suggest that the geographical distribution of human resources in the ACES compared could be improved in order to meet the satisfaction of the local health needs in each ACES. Based on correlation analysis, it was concluded that the relative level of equity of access is positively correlated with the rate of use of hospital emergency rooms, suggesting effects of transferring demand from health centers to hospitals.
- Benchmarks and sediment source(s) of the 1755 Lisbon tsunami deposit at Boca do Rio EstuaryPublication . Font, Eric; Veiga-Pires, C.; Pozo, Manuel; Nave, Silvia; Costas, Susana; Ruiz, F.; Abad, Manuel; Simões, Nuno; Duarte, Sílvia; Rodriguez-Vidal, J.Standardizing the signature of tsunami deposits has been identified as a major limitation for the identification of paleo-tsunami deposits. This limitation mostly arises from the strongly source-dependent nature of these deposits, which in turn determines their composition and depositional architecture, and from the effect of the local morphology of the corresponding depositional environment. Here, we provide new highresolution mineralogical, geochemical and micro/macrofauna data of the 1755 tsunami layer of Boca do Rio estuary (Algarve, Portugal) with the aim of unraveling the signatures of estuarine tsunami deposits and linking them to possible sediment sources. We also apply for the first time diffuse reflectance spectrophotometry (DRS) analysis. Our results show that the 1755 tsunami deposit of the Boca do Rio estuary is featured by an enhancement in Sr and Ca, which are linked to the input of biogenic and detrital carbonates (shell fragments and limestone clasts) from the beach foreshore and a strong depletion in most terrestrial- and marine-sensitive indicators. The latter is interpreted as resulting from the reworking of the estuarine clays and subsequent dilution within a huge volume of sand eroded from the coastal barrier. It confirms that in the case of the Boca do Rio estuary, the sediment source is essentially proximal and coastal. Textural and mineralogical features between the base and the top of the tsunami layer suggest the imprint of run-up and backwash currents derived from a unique wave. Micro and macrofauna analysis and DRS data of the siliciclastic fraction show slight but significant environmental changes occurring just after the tsunami, which could be provoked by an eventual closure of the estuary mouth.
- Two-variable linear programming: a graphical tool with mathematicaPublication . Pereira, José C.; Fernandes, SusanaThis paper presents the GLP-Tool, an interactive tool for graphical linear programming involving two variables. The GLP-Tool is designed to solve user-defined linear programming problems with two variables. Implemented using the computer algebra system Mathematica, this interactive tool allows the user to dynamically explore different objective functions and constraint sets, and also perform post-optimal and sensitivity analysis. All the GLP-Tool functionalities are represented graphically and updated in real time. These interactive, dynamic, and graphical features make the GLP-Tool a powerful tool for teaching linear programming both in undergraduate and high school courses. After completing its development, we intend to make the GLP-Tool available at the Wolfram Demonstrations Project website.
- Atlantic Area Eunis Habitats. Adding new habitat types from European Atlantic coast to the EUNIS Habitat ClassificationPublication . Monteiro, P.Marine protection has been emphasized through global and European conventions which highlighted the need for the establishment of special areas of conservation. Classification and habitat mapping have been developed to enhance the assessment of marine environment and improve spatial and strategic planning of human activities and to help on the implementation of ecosystem based management. European Nature information System (EUNIS) is a comprehensive habitat classification system to facilitate the harmonised description and collection of habitat and biotopes that has been developed by the European Environment Agency (EEA) in collaboration with experts from institutions throughout Europe.
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