Comparison of Several Algorithms to Estimate Activity Counts with Smartphones as an Indication of Physical Activity Level

Background Dedicated devices like GT3X+, Actical or ActivPal have been widely used to measure physical activity (PA) levels by using cut-points on activity counts. However, the calculation of activity counts relies on proprietary software. Since smartphones incorporate accelerometers they are suitable candidates to determine PA levels in a wider population. Objective Our aim was to compare several algorithms so that smartphones can reproduce the results obtained with GT3X+. The influence of smartphone location was also investigated. Methods Volunteers participated in the experiment performing several activities carrying two smartphones (hip and pocket) and one GT3X+ (hip). Four algorithms (A1–A4) were considered to obtain GT3X+ counts from smartphone accelerometer signals. A1 was based on a traditional filtering on temporal domain and a posterior calculation of the area under the curve. A2 was based on computing histograms of acceleration values, which were used as independent variables in a standard linear regression procedure. A3 also used a linear regression, but in this case the independent variables were power spectrum bands, leading to a kind of filtering in the frequency domain. A4 was based on a direct measure of area under the rectified curve of the raw accelerometer signal. Performance was measured in terms of raw activity counts or the corresponding PA level classification. The influence of the algorithm was tested with a Quade test. Multiple comparisons were performed with Wilcoxon test with Bonferroni's correction. Besides, battery consumption was also measured as a secondary parameter. The output of the selected algorithm was compared with GT3X+ counts using correlation (pearson and spearman) and agreement (Intra-Class Coefficient, ICC and Bland–Altmann plots for raw counts, and weighted kappa for activity levels). Several experimental conditions regarding smartphone location were compared with Wilcoxon tests. Results Thirty-two volunteers participated in the experiment. More refined algorithms based on filtering techniques did not prove to achieve better performance than A2 or A4. In terms of classification of PA level, A4 got the lowest error rate, although in some cases the differences with other algorithms were not statistically significant (p-value > 0.05). A4 is also the simplest and the one that implies less battery depletion. The comparison of A4 with GT3X+ gave good agreement () and correlation () for raw counts and good agreement when classifying four or two PA levels ( or 0.923 respectively). Besides, in real situations, activity classification into four levels was significantly improved () if data from several body locations were used to find model parameters. Conclusions Simple algorithms can reproduce the results of GT3X+. Thus, smartphones could be used to control the fulfillment of PA recommendations previously validated with cut-points. However, it must be acknowledged that accelerometers are not the gold standard to measure PA

Introducing dynamism in emotional agent societies

[EN] This paper presents the development of a dynamic emotional model to be employed in agent societies. The proposed model is based on the PAD emotional model and allows the representation of the emotional contagion phenomena of a heterogeneous group of agents that are capable of express emotions. The model is mainly based on three elements: personality, empathy and affinity. These elements allow the characterisation of each individual, causing them susceptible to vary in some degree the emotions of other individuals. Additionally, the model allows defining of the social emotion of this group of agents. (C) 2017 Elsevier B.V. All rights reserved.This work is partially supported by the MINECO/FEDER TIN2015-65515-C4-1-R and the FPI grant AP2013-01276 awarded to Jaime-Andres Rincon. This work is supported by COMPETE: POCI-01-0145-FEDER-007043 and FCT - Fundacao para a Ciencia e Tecnologia within the projects UID/CEC/00319/2013 and Post-Doc scholarship SFRH/BPD/102696/2014 (A. Costa).Rincon, J.; Costa, A.; Villarrubia, G.; Julian Inglada, VJ.; Carrascosa Casamayor, C. (2018). Introducing dynamism in emotional agent societies. Neurocomputing. 272:27-39. https://doi.org/10.1016/j.neucom.2017.03.091S273927

Application of stages of change model to adolescents' physical activity in relation to psychological variables

AIM: This study investigated the stages of change in physical activity in relation to psychological variables: self-efficacy, physical self-concept and barriers to physical activity, as well as gender. Furthermore, cluster profiles were created based on psychological variables to be compared with stages of change groups. METHODS: Data were obtained from a representative sample of adolescents (N.=1618, 14.46±1.28 years) from Aragon region (Spain). The different strata were selected according to the geographical region, environment, type of school, age and gender. RESULTS: Males (75.5%) and very active adolescents (96.9% participant boys and 93.5% participants girls) were more prevalent in the action and maintenance groups. We found significant differences in psychosocial variables by stages of change and gender, showing higher scores in active groups for physical self-concept (effects of gender and stages of change: F(1, 1618)=313.82 P<0.001, ¿²=0.230) and self-efficacy (F(1, 1618)=324.34 P<0.001, ¿²=0.236), and lower scores in passive groups for intrapersonal (F(1, 1618)=179.73 P<0.001, ¿²=0.146) and extrapersonal barriers (F(1, 1618)=189.42 P<0.001, ¿²=0.153). Psychological cluster profiles created with these variables showed significant relationships with stages of change groups (¿²(1)=162,76, P<0.001; Pearson R=0.359 P<0.001). CONCLUSION: The findings of the research suggest the importance of the study, showing strong determinants of PA, physical self-concept, self-efficacy and perceived barriers, in relation to the intention to change behaviour, not only stage of change model variables. Furthermore, the study can be relevant to designing more effective health promotion programmes in the adolescent population

Solving Large-Scale Optimization Problems Related to Bell's Theorem

Impossibility of finding local realistic models for quantum correlations due to entanglement is an important fact in foundations of quantum physics, gaining now new applications in quantum information theory. We present an in-depth description of a method of testing the existence of such models, which involves two levels of optimization: a higher-level non-linear task and a lower-level linear programming (LP) task. The article compares the performances of the existing implementation of the method, where the LPs are solved with the simplex method, and our new implementation, where the LPs are solved with a matrix-free interior point method. We describe in detail how the latter can be applied to our problem, discuss the basic scenario and possible improvements and how they impact on overall performance. Significant performance advantage of the matrix-free interior point method over the simplex method is confirmed by extensive computational results. The new method is able to solve problems which are orders of magnitude larger. Consequently, the noise resistance of the non-classicality of correlations of several types of quantum states, which has never been computed before, can now be efficiently determined. An extensive set of data in the form of tables and graphics is presented and discussed. The article is intended for all audiences, no quantum-mechanical background is necessary.Comment: 19 pages, 7 tables, 1 figur

External fixation in tumour pathology

An appraisal of the clinical records of patients with malignant bone tumours enabled us to identify 61 whom we have treated by external fixation. There were 38 males and 23 females with ages ranging from 4 to 58 years, the mean being 14 years. The average period of follow-up was 6 years (1-12 years). For the purpose of our analysis the patients were divided into three groups according to whether the fixator was fitted before, during or after tumour resection

Breakdown of the Kondo Effect in Critical Antiferromagnets

The breakdown of the Kondo effect may be the origin of the anomalous properties of the heavy-fermion compounds at low temperatures. We study the dynamics of one impurity embedded in an antiferromagnetic host at the quantum critical point and show that the impurity is not screened and develops a power law correlation function. This suggests that the breakdown of the Kondo effect can simply be a consequence of the system's proximity to the quantum critical point.Comment: To appear in Physical Review B (Brief Reports

Prodsimplicial-Neighborly Polytopes

Simultaneously generalizing both neighborly and neighborly cubical polytopes, we introduce PSN polytopes: their k-skeleton is combinatorially equivalent to that of a product of r simplices. We construct PSN polytopes by three different methods, the most versatile of which is an extension of Sanyal and Ziegler's "projecting deformed products" construction to products of arbitrary simple polytopes. For general r and k, the lowest dimension we achieve is 2k+r+1. Using topological obstructions similar to those introduced by Sanyal to bound the number of vertices of Minkowski sums, we show that this dimension is minimal if we additionally require that the PSN polytope is obtained as a projection of a polytope that is combinatorially equivalent to the product of r simplices, when the dimensions of these simplices are all large compared to k.Comment: 28 pages, 9 figures; minor correction

Influencing over people with a social emotional model

[EN] This paper presents an approach of a social emotional model, which allows to extract the social emotion of a group of intelligent entities. The emotional model PAD allows to represent the emotion of an intelligent entity in 3-D space, allowing the representation of different emotional states. The social emotional model presented in this paper uses individual emotions of each one of the entities, which are represented in the emotional space PAD. Using a social emotional model within intelligent entities allows the creation of more real simulations, in which emotional states can influence decision-making. The result of this social emotional mode is represented by a series of examples, which are intended to represent a number of situations in which the emotions of each individual modify the emotion of the group. Moreover, the paper introduces an example which employs the proposed model in order to learn and predict future actions trying to influence in the social emotion of a group of people.This work is partially supported by the MINECO/FEDER TIN2015-65515-C4-1-R and the FPI grant AP2013-01276 awarded to Jaime-Andres Rincon.Rincon, J.; De La Prieta-Pintado, F.; Zanardini, D.; Julian Inglada, VJ.; Carrascosa Casamayor, C. (2017). Influencing over people with a social emotional model. Neurocomputing. 231:47-54. https://doi.org/10.1016/j.neucom.2016.03.107S475423