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Search Results: 1 - 10 of 413 matches for " Lluis Fuentemilla "
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Population Level Inference for Multivariate MEG Analysis
Anna Jafarpour, Gareth Barnes, Lluis Fuentemilla, Emrah Duzel, Will D. Penny
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0071305
Abstract: Multivariate analysis is a very general and powerful technique for analysing Magnetoencephalography (MEG) data. An outstanding problem however is how to make inferences that are consistent over a group of subjects as to whether there are condition-specific differences in data features, and what are those features that maximise these differences. Here we propose a solution based on Canonical Variates Analysis (CVA) model scoring at the subject level and random effects Bayesian model selection at the group level. We apply this approach to beamformer reconstructed MEG data in source space. CVA estimates those multivariate patterns of activation that correlate most highly with the experimental design; the order of a CVA model is then determined by the number of significant canonical vectors. Random effects Bayesian model comparison then provides machinery for inferring the optimal order over the group of subjects. Absence of a multivariate dependence is indicated by the null model being the most likely. This approach can also be applied to CVA models with a fixed number of canonical vectors but supplied with different feature sets. We illustrate the method by identifying feature sets based on variable-dimension MEG power spectra in the primary visual cortex and fusiform gyrus that are maximally discriminative of data epochs before versus after visual stimulation.
ENOBIO - First tests of a dry electrophysiology electrode using carbon nanotubes
Giulio Ruffini,Stephen Dunne,Esteve Farres,Paul C. P. Watts,Ernest Mendoza,Ravi Silva,Carles Grau,Josep Marco-Pallares,Lluis Fuentemilla,Bjorn Vandecasteele
Physics , 2006,
Abstract: We describe the development and first tests of Enobio, a dry electrode sensor concept for biopotential applications. In the proposed electrodes, the tip of the electrode is covered with a forest of multi-walled CNTs that can be coated with Ag/AgCl to provide ionic-electronic transduction. The CNT brush-like structure is to penetrate the outer layers of the skin improving electrical contact as well as increae the contact surface area. In this paper, we report the results of the first tests of this concept -- immersion on saline solution and pig skin signal detection. These indicate performance on a par with state of the art research-oriented wet electrodes.
A Flexible POS tagger Using an Automatically Acquired Language Model
Lluis Marquez,Lluis Padro
Computer Science , 1997,
Abstract: We present an algorithm that automatically learns context constraints using statistical decision trees. We then use the acquired constraints in a flexible POS tagger. The tagger is able to use information of any degree: n-grams, automatically learned context constraints, linguistically motivated manually written constraints, etc. The sources and kinds of constraints are unrestricted, and the language model can be easily extended, improving the results. The tagger has been tested and evaluated on the WSJ corpus.
Core Topics in Mechanical Ventilation
Lluis Blanch
Critical Care , 2009, DOI: 10.1186/cc7951
Abstract: The contents of Core Topics in Mechanical Ventilation edited by Ian Mackenzie can be separated into two general parts. Several chapters cover general respiratory physiology, which is essential to understand how mechanical ventilation works and interacts with cardio-respiratory performance. It is worth mentioning the good contributions on the physiology of gas exchange, carbon dioxide balance and cardio-respiratory interactions. Some chapters are dedicated to adjuncts of mechanical ventilation, including both general and custom adjuncts used in mechanically ventilated patients. Of note are the chapters dedicated to the effects and administration of oxygen and heliox, and to sedation, analgesia, paralysis and nutrition.The second part is devoted to mechanical ventilation. The reader can find recommendations about how to set the ventilator in several clinical scenarios such as asthma, chronic obstructive pulmonary disease, and chest, burn and blast injuries. One specific chapter is devoted to adverse effects and complications of mechanical ventilation. This chapter deals in a very comprehensive manner with management of the difficult airway, unplanned extubation and how to minimize and manage ventilation-induced lung injury (barotrauma, volutrauma, and atelectrauma), among others. The management of acute lung injury and acute respiratory distress syndrome are not covered in dedicated chapters, but major principles are included as paragraphs in distinct parts of the book. The same is the case for non-invasive mechanical ventilation, which nowadays can be considered an independent discipline that extends beyond anesthesia and intensive care departments. Three chapters deserve mention for their particular relevance: Management of the artificial airway, Modes of mechanical ventilation, and Mechanical ventilation for transport. These chapters are extensive and comprehensive and include technical documentation as well as tables and figures that are self-explanatory. I am als
Re-thinking cell cycle regulators: the cross-talk with metabolism
Lluis Fajas
Frontiers in Oncology , 2013, DOI: 10.3389/fonc.2013.00004
Abstract: Analysis of genetically engineered mice deficient in cell cycle regulators, including E2F1, cdk4, and pRB, showed that the major phenotypes are metabolic perturbations. These key cell cycle regulators contribute to lipid synthesis, glucose production, insulin secretion, and glycolytic metabolism. It has been shown that deregulation of these pathways can lead to metabolic perturbations and related metabolic diseases, such as obesity and type II diabetes. The cyclin–cdk–Rb–E2F1 pathway regulates adipogenesis in addition to its well-described roles in cell cycle regulation and cancer. It was also shown that E2F1 directly participates in the regulation of pancreatic growth and function. Similarly, cyclin D3, cdk4, and cdk9 are also adipogenic factors with strong effects on whole organism metabolism. These examples support the emerging notion that cell cycle regulatory proteins also modulate metabolic processes. These cell cycle regulators are activated by insulin and glucose, even in non-proliferating cells. Most importantly, these cell cycle regulators trigger the adaptive metabolic switch that normal and cancer cells require in order to proliferate. These changes include increased lipid synthesis, decreased oxidative metabolism, and increased glycolytic metabolism. In summary, these factors are essential regulators of anabolic biosynthetic processes, blocking at the same time oxidative and catabolic pathways, which is reminiscent of cancer cell metabolism.
An area law for the entropy of low-energy states
Lluis Masanes
Physics , 2009, DOI: 10.1103/PhysRevA.80.052104
Abstract: It is often observed in the ground state of spatially-extended quantum systems with local interactions that the entropy of a large region is proportional to its surface area. In some cases, this area law is corrected with a logarithmic factor. This contrasts with the fact that in almost all states of the Hilbert space, the entropy of a region is proportional to its volume. This paper shows that low-energy states have (at most) an area law with the logarithmic correction, provided two conditions hold: (i) the state has sufficient decay of correlations, (ii) the number of eigenstates with vanishing energy-density is not exponential in the volume. These two conditions are satisfied by many relevant systems. The central idea of the argument is that energy fluctuations inside a region can be observed by measuring the exterior and a superficial shell of the region.
Evanescent gravitational mass
Lluis Bel
Physics , 2009,
Abstract: A simple and {\it innocent} modification of Poisson's equation leads to a modified Newtonnian theory of gravitation where a localized and {\it positive} energy density of the gravitational field contributes to its own source. The result is that the total {\it active gravitational mass} of a compact object is the sum of its {\it proper mass} and an {\it evanescent gravitational mass} which is a mass equivalent to the gravitational energy.
Space-time models derived from Schwarzschild's solution
Lluis Bel
Physics , 2008,
Abstract: We discuss two space-time models: one is expanding, the other is static. They are both derived from Schwarzschild's exterior solution. But they differ in the implementation of the parallelism at a distance and the choice of their master frame of reference.
A distinguished set of modes in an accelerated frame of reference
Lluis Bel
Physics , 1997,
Abstract: We construct a distinguished set of positive and negative energy modes of the Klein-Gordon equation for any Born frame of reference in Minkowski's space-time. Unlike the case of a galilean frame of reference it is unclear whether this set of modes may be an appropriate basis to define the vacuum of a quantized scalar field in an accelerated cavity.
Eta decays involving photons
Lluis Ametller
Physics , 2001, DOI: 10.1238/Physica.Topical.099a00045
Abstract: The decays of the eta meson are reviewed in the framework of Chiral Perturbation Theory. Particular attention is devoted to the electromagnetic channels involving photons, either in the final or intermediate states.
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