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Publicações

2016

Microbes as Engines of Ecosystem Function: When Does Community Structure Enhance Predictions of Ecosystem Processes?

Autores
Graharni, EB; Knelman, JE; Schindlbacher, A; Siciliano, S; Breulmann, M; Yannarell, A; Bemans, JM; Abell, G; Philippot, L; Prosser, J; Foulquier, A; Yuste, JC; Glanville, HC; Jones, DL; Angel, F; Salminen, J; Newton, RJ; Buergmann, H; Ingram, LJ; Hamer, U; Siljanen, HMP; Peltoniemi, K; Potthast, K; Baneras, L; Hartmann, M; Banerjee, S; Yu, RQ; Nogaro, G; Richter, A; Koranda, M; Castle, SC; Goberna, M; Song, B; Chatterjee, A; Nunes, OC; Lopes, AR; Cao, YP; Kaisermann, A; Hallin, S; Strickland, MS; Garcia Pausas, J; Barba, J; Kang, H; Isobe, K; Papaspyrou, S; Pastorelli, R; Lagomarsino, A; Lindstrom, ES; Basiliko, N; Nemergut, DR;

Publicação
FRONTIERS IN MICROBIOLOGY

Abstract
Microorganisms are vital in mediating the earth's biogeochemical cycles; yet, despite our rapidly increasing ability to explore complex environmental microbial communities, the relationship between microbial community structure and ecosystem processes remains poorly understood. Here, we address a fundamental and unanswered question in microbial ecology: 'When do we need to understand microbial community structure to accurately predict function?' We present a statistical analysis investigating the value of environmental data and microbial community structure independently and in combination for explaining rates of carbon and nitrogen cycling processes within 82 global datasets. Environmental variables were the strongest predictors of process rates but left 44% of variation unexplained on average, suggesting the potential for microbial data to increase model accuracy. Although only 29% of our datasets were significantly improved by adding information on microbial community structure, we observed improvement in models of processes mediated by narrow phylogenetic guilds via functional gene data, and conversely, improvement in models of facultative microbial processes via community diversity metrics. Our results also suggest that microbial diversity can strengthen predictions of respiration rates beyond microbial biomass parameters, as 53% of models were improved by incorporating both sets of predictors compared to 35% by microbial biomass alone. Our analysis represents the first comprehensive analysis of research examining links between microbial community structure and ecosystem function. Taken together, our results indicate that a greater understanding of microbial communities informed by ecological principles may enhance our ability to predict ecosystem process rates relative to assessments based on environmental variables and microbial physiology.

2016

Decision support for the strategic behaviour of electricity market players

Autores
Pinto, T;

Publicação

Abstract

2016

Dense motion field estimation from myocardial boundary displacements

Autores
Morais, P; Queiros, S; Ferreira, A; Rodrigues, NF; Baptista, MJ; D'hooge, J; Vilaca, JL; Barbosa, D;

Publicação
INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING

Abstract
Minimally invasive cardiovascular interventions guided by multiple imaging modalities are rapidly gaining clinical acceptance for the treatment of several cardiovascular diseases. These images are typically fused with richly detailed pre-operative scans through registration techniques, enhancing the intra-operative clinical data and easing the image-guided procedures. Nonetheless, rigid models have been used to align the different modalities, not taking into account the anatomical variations of the cardiac muscle throughout the cardiac cycle. In the current study, we present a novel strategy to compensate the beat-to-beat physiological adaptation of the myocardium. Hereto, we intend to prove that a complete myocardial motion field can be quickly recovered from the displacement field at the myocardial boundaries, therefore being an efficient strategy to locally deform the cardiac muscle. We address this hypothesis by comparing three different strategies to recover a dense myocardial motion field from a sparse one, namely, a diffusion-based approach, thin-plate splines, and multiquadric radial basis functions. Two experimental setups were used to validate the proposed strategy. First, an in silico validation was carried out on synthetic motion fields obtained from two realistic simulated ultrasound sequences. Then, 45 mid-ventricular 2D sequences of cine magnetic resonance imaging were processed to further evaluate the different approaches. The results showed that accurate boundary tracking combined with dense myocardial recovery via interpolation/diffusion is a potentially viable solution to speed up dense myocardial motion field estimation and, consequently, to deform/compensate the myocardial wall throughout the cardiac cycle. Copyright (C) 2015 John Wiley & Sons, Ltd.

2016

Automatic Cattle Identification Using Graph Matching Based on Local Invariant Features

Autores
Monteiro, FC;

Publicação
IMAGE ANALYSIS AND RECOGNITION (ICIAR 2016)

Abstract
Cattle muzzle classification can be considered as a biometric identifier important to animal traceability systems to ensure the integrity of the food chain. This paper presents a muzzle-based classification system that combines local invariant features with graph matching. The proposed approach consists of three phases; namely feature extraction, graph matching, and matching refinement. The experimental results showed that our approach is superior than existing works as ours achieves an all correct identification for the tested images. In addition, the results proved that our proposed method achieved this high accuracy even if the testing images are rotated in various angles.

2016

Communication-free control solution for the provision of frequency regulation services in HVDC grids: Numerical simulation and experimental validation in a reduced scale platform

Autores
Moreira, CL; Gouveia, JR; Rodrigues, J; Silva, B; Peças Lopes, JA;

Publicação
CIGRE Session 46

Abstract
The development of future HVDC grids for transnational interconnections and offshore wind farms development should be compliant with specific requirements regarding frequency support and inertia emulation. Therefore, this paper presents the development of communication-free control solutions capable of dealing with these control requirements. The proposed solution exploit a coordinated control approach between offshore wind turbines and VSC-HVDC converter stations based on the DC grid voltage modulation. The effectiveness of the proposed control solutions are demonstrated to be of utmost importance for improving future grids frequency regulation capabilities. Recognizing that numerical simulations provide valuable knowledge regarding HVDC grids operation and control, this paper introduces a further step encompassing the development of a reduced scale laboratorial prototype of a DC grid making possible the demonstration of key frequency control functionalities. Following the theoretical/conceptual background that is demonstrated through numerical simulation, laboratorial tests were then performed in order to test and demonstrate the performance and effectiveness of the proposed control mechanisms that future HVDC grids will provide to frequency control in mainland AC grids.

2016

Aptamer-based fiber sensor for thrombin detection

Autores
Coelho, L; Marques Martins de Almeida, JMM; Santos, JL; da Silva Jorge, PAD; Martins, MCL; Viegas, D; Queiros, RB;

Publicação
JOURNAL OF BIOMEDICAL OPTICS

Abstract
The detection of thrombin based on aptamer binding is studied using two different optical fiber-based configurations: long period gratings coated with a thin layer of titanium dioxide and surface plasmon resonance devices in optical fibers coated with a multilayer of gold and titanium dioxide. These structures are functionalized and the performance to detect thrombin in the range 10 to 100 nM is compared in transmission mode. The sensitivity to the surrounding refractive index (RI) of the plasmonic device is higher than 3100 nmRIU(-1) in the RI range 1.335 to 1.355, a factor of 20 greater than the sensitivity of the coated grating. The detection of 10 nM of thrombin was accomplished with a wavelength shift of 3.5 nm and a resolution of 0.54 nM. (C) 2016 Society of Photo-Optical Instrumentation Engineers (SPIE)

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