Search for top squark pair production in the 3-body decay mode with a single lepton final state with the ATLAS detector

In this work, the results from two searches for direct pair production of top squarks, the supersymmetric partner of the top quark, are reported. Both searches focus on final states with one isolated electron or muon, multiple hadronic jets, and large missing transverse momentum. The first analysis is performed on data from proton-proton collisions delivered by the Large Hadron Collider at a centre-of-mass energy of 13 TeV and recorded by the ATLAS detector within the years 2015 and 2016, corresponding to an integrated luminosity of 36.1 fb^-1. The second analysis is performed on the full Run 2 dataset of proton-proton collisions at a centre-of-mass energy 13 TeV recorded by the ATLAS detector within the period from 2015 to 2018, corresponding to an integrated luminosity of 139 fb^-1. A particular top squark decay mode is considered, where the mass difference between the top squark and the neutralino is smaller than the top quark and as a result each top squark decays via a 3-body process into a b quark, a W boson, and a neutralino. In this phase space, the top squark pair events closely resemble top quark pair processes. No significant deviation from the predicted Standard Model background is observed in both searches. Hence, exclusion limits at 95 % confidence level on the supersymmetric model are determined. In the first analysis, top squarks with masses up to 460 GeV are excluded. With the results from the second analysis, the exclusion limit is extended and top squarks with masses up to 720 GeV and neutralino masses up to 580 GeV are excluded

Infants' mu suppression during the observation of real and mimicked goal-directed actions

Since their discovery in the early 1990s, mirror neurons have been proposed to be related to many social-communicative abilities, such as imitation. However, research into the early manifestations of the putative neural mirroring system and its role in early social development is still inconclusive. In the current EEG study, mu suppression, generally thought to reflect activity in neural mirroring systems was investigated in 18- to 30-month-olds during the observation of object manipulations as well as mimicked actions. EEG power data recorded from frontal, central, and parietal electrodes were analysed. As predicted, based on previous research, mu wave suppression was found over central electrodes during action observation and execution. In addition, a similar suppression was found during the observation of intransitive, mimicked hand movements. To a lesser extent, the results also showed mu suppression at parietal electrode sites, over all three conditions. Mu wave suppression during the observation of hand movements and during the execution of actions was significantly correlated with quality of imitation, but not with age or language level

Comparing Multi-objective and Threshold-moving ROC Curve Generation for a Prototype-based Classifier

Proceedings of: GECCO 2013: 15th International Conference on Genetic and Evolutionary Computation Conference (Amsterdam, The Netherlands, July 06-10, 2013): a recombination of the 22nd International Conference on Genetic Algorithms (ICGA) and the 18th Annual Genetic Programming Conference (GP), Amsterdam, The Netherlands, July 06-10, 2013Receiver Operating Characteristics (ROC) curves represent the performance of a classifier for all possible operating con-ditions, i.e., for all preferences regarding the tradeoff be-tween false positives and false negatives. The generation of a ROC curve generally involves the training of a single classifier for a given set of operating conditions, with the subsequent use of threshold-moving to obtain a complete ROC curve. Recent work has shown that the generation of ROC curves may also be formulated as a multi-objective optimization problem in ROC space: the goals to be min-imized are the false positive and false negative rates. This technique also produces a single ROC curve, but the curve may derive from operating points for a number of different classifiers. This paper aims to provide an empirical compar-ison of the performance of both of the above approaches, for the specific case of prototype-based classifiers. Results on synthetic and real domains shows a performance advantage for the multi-objective approach.GECCO 2013 Presentation slidesThis work has been funded by the Spanish Ministry of Science under contract TIN2011-28336 (MOVES project)En prens