Browsing by Issue Date, starting with "2013-06"
Now showing 1 - 10 of 18
Results Per Page
Sort Options
- Isolation and fatty acid profile of selected microalgae strains from the Red Sea for biofuel productionPublication . Pereira, Hugo; Barreira, Luisa; Custodio, Luisa; Alrokayan, Salman; Mouffouk, Fouzi; Varela, Joao; Abu-Salah, Khalid M.; Ben-Hamadou, RadhouanThe isolation of lipid-rich autochthonous strains of microalgae is a crucial stage for the development of a microalgae-based biofuel production plant, as these microalgae already have the necessary adaptations to withstand competition, predation and the temperatures observed at each production site. This is particularly important in extreme climates such as in Saudi Arabia. Resorting to fluorescence activated cell sorting (FACS) we screened for and isolated several microalgal strains from samples collected from the Red Sea. Relying on the fluorescence of BODIPY 505/515 (4,4-difluoro-1,3,5,7-tetramethyl-4-bora-3a,4a-diazasindacene) and growth performance, four promising candidates were identified and the total lipid content and fatty acid profile was assessed for biofuels production. Selected isolates were classified as chlorophytes, belonging to three different genera: Picochlorum, Nannochloris and Desmochloris. The lipid contents were assessed microscopically by means of BODIPY 505/515-associated fluorescence to detect intracellular lipid bodies, which revealed several lipid drops in all selected strains. This result was confirmed by lipid gravimetric determination, which demonstrated that all strains under study presented inner cell lipid contents ranging from 20% to 25% of the biomass dry weight. Furthermore, the fatty acid methyl esters profile of all strains seems ideal for biodiesel production due to a low degree of polyunsaturated fatty acid methyl esters and high amount of palmitic and oleic acids.
- Sleep promotes the extraction of grammatical rulesPublication . Nieuwenhuis, Ingrid L. C.; Folia, Vasiliki; Forkstam, Christian; Jensen, Ole; Petersson, Karl MagnusGrammar acquisition is a high level cognitive function that requires the extraction of complex rules. While it has been proposed that offline time might benefit this type of rule extraction, this remains to be tested. Here, we addressed this question using an artificial grammar learning paradigm. During a short-term memory cover task, eighty-one human participants were exposed to letter sequences generated according to an unknown artificial grammar. Following a time delay of 15 min, 12 h (wake or sleep) or 24 h, participants classified novel test sequences as Grammatical or Non-Grammatical. Previous behavioral and functional neuroimaging work has shown that classification can be guided by two distinct underlying processes: (1) the holistic abstraction of the underlying grammar rules and (2) the detection of sequence chunks that appear at varying frequencies during exposure. Here, we show that classification performance improved after sleep. Moreover, this improvement was due to an enhancement of rule abstraction, while the effect of chunk frequency was unaltered by sleep. These findings suggest that sleep plays a critical role in extracting complex structure from separate but related items during integrative memory processing. Our findings stress the importance of alternating periods of learning with sleep in settings in which complex information must be acquired.
- The first detection of Leishmania major in naturally infected Sergentomyia minuta in PortugalPublication . Campino, Lenea; Cortes, Sofia; Dionisio, Lidia; Neto, Luis; Afonso, Maria Odete; Maia, CarlaPhlebotomine sandflies of the genus Sergentomyia are widely distributed throughout the Old World. It has been suggested that Sergentomyia spp are involved in the transmission of Leishmania in India and Africa, whereas Phlebotomus spp are thought to be the sole vectors of Leishmania in the Old World. In this study, Leishmania major DNA was detected in one Sergentomyia minuta specimen that was collected in the southern region of Portugal. This study challenges the dogma that Leishmania is exclusively transmitted by species of the genus Phlebotomus in the Old World.
- Exploring the potential of Data Envelopment Analysis for performance-related-pay in health care provisionPublication . Kalinichenko, Olena; Amado, Carla; Santos, Sérgio Pereira dosIn this paper we explore the potential use of Data Envelopment Analysis (DEA) for enhancing pay-for-performance (P4P) in health care provision. Firstly, based on the literature review, we reflect on the state of the art in the P4P design, focusing on some of the controversial issues in the literature and discussing the potential contribution of DEA to addressing these issues. Secondly, we analyse the P4P programme applied to Portuguese Family Health Units (FHUs) to conclude about the possible use of DEA for its improvement.
- A note on Riesz fractional integrals in the limiting case alpha(x)p(x) a parts per thousand nPublication . Samko, StefanWe show that the Riesz fractional integration operator I (alpha(center dot)) of variable order on a bounded open set in Omega aS, a"e (n) in the limiting Sobolev case is bounded from L (p(center dot))(Omega) into BMO(Omega), if p(x) satisfies the standard logcondition and alpha(x) is Holder continuous of an arbitrarily small order.
- Over 130 years of survival by a small, isolated population of Favia gravida corals at Ascension Island (South Atlantic)Publication . Hoeksema, Bert W.; Wirtz, Peter
- Existence of weak solutions for the generalized Navier-Stokes equations with dampingPublication . de Oliveira, H. B.In this work we consider the generalized Navier-Stokes equations with the presence of a damping term in the momentum equation. The problem studied here derives from the set of equations which govern isothermal flows of incompressible and homogeneous non-Newtonian fluids. For the generalized Navier-Stokes problem with damping, we prove the existence of weak solutions by using regularization techniques, the theory of monotone operators and compactness arguments together with the local decomposition of the pressure and the Lipschitz-truncation method. The existence result proved here holds for any and any sigma > 1, where q is the exponent of the diffusion term and sigma is the exponent which characterizes the damping term.
- Real-Time Object Recognition Based on Cortical Multi-scale KeypointsPublication . Terzic, Kasim; Rodrigues, J. M. F.; du Buf, J. M. H.In recent years, a large number of impressive object categorisation algorithms have surfaced, both computational and biologically motivated. While results on standardised benchmarks are impressive, very few of the best-performing algorithms took run-time performance into account, rendering most of them useless for real-time active vision scenarios such as cognitive robots. In this paper, we combine cortical keypoints based on primate area V1 with a state-of-the-art nearest neighbour classifier, and show that such a system can approach state-of-the-art categorisation performance while meeting the real-time constraint.
- A field, tracking and video editor tool for a football resource plannerPublication . Rodrigues, Pedro; Cardoso, Pedro J. S.; Rodrigues, J. M. F.The current Football Resource Planning (FRP) systems integrate both internal and external information management across the entire professional football organization, including features to gather automated information from the teams, not only on the competition part but also on the preparation. In this paper, we present three of those tools from the Footdata’s web/cloud FRP system: Field Editor (FE), Tracking Editor (TE) and Video Editor (VE). The FE provides the coach with a platform where he can represent the tactical movements for his team within an animated context. On the other hand, the TE allows the interaction with the Footdata tracking system. Finally, the VE tool offers the possibility for a coach to watch, cut and analyze football videos.
- Adaptation of Listeria monocytogenes in a simulated cheese medium: effects on virulence using the Galleria mellonella infection modelPublication . Schrama, Denise; Helliwell, N.; Neto, L.; Faleiro, Maria LeonorThe aim of this study was to evaluate the effect of the acid and salt adaptation in a cheese-based medium on the virulence potential of Listeria monocytogenes strains isolated from cheese and dairy processing environment using the Galleria mellonella model. Four L.monocytogenes strains were exposed to a cheese-based medium in conditions of induction of an acid tolerance response and osmotolerance response (pH 5 center dot 5 and 3 center dot 5% w/v NaCl) and injected in G.mellonella insects. The survival of insects and the L.monocytogenes growth kinetics in insects were evaluated. The gene expression of hly, actA and inlA genes was determined by real-time PCR. The adapted cells of two dairy strains showed reduced insect mortality (P<0 center dot 05) in comparison with nonadapted cells. Listeria monocytogenes Scott A was the least virulent, whereas the cheese isolate C882 caused the highest insect mortality, and no differences (0 center dot 05) was found between adapted and nonadapted cells. The gene expression results evidenced an overexpression of virulence genes in cheese-based medium, but not in simulated insect-induced conditions. Our results suggest that adaptation to low pH and salt in a cheese-based medium can affect the virulence of L.monocytogenes, but this effect is strain dependent. Significance and Impact of the Study In this study, the impact of adaptation to low pH and salt in a cheese-based medium on L.monocytogenes virulence was tested using the Wax Moth G.mellonella model. This model allowed the differentiation of the virulence potential between the L.monocytogenes strains. The effect of adaptation on virulence is strain dependent. The G.mellonella model revealed to be a prompt method to test food-related factors on L.monocytogenes virulence.