Direct Sparse Mapping

Photometric bundle adjustment (PBA) accurately estimates geometry from video. However, current PBA systems have a temporary map that cannot manage scene reobservations. We present, direct sparse mapping, a full monocular visual simultaneous localization and mapping (SLAM) based on PBA. Its persistent map handles reobservations, yielding the most accurate results up to date on EuRoC for a direct method

First principles quasiparticle damping rates in bulk lead

First principles calculations of the damping rates (inverse inelastic lifetimes) of low energy quasiparticles in bulk Pb are presented. Damping rates are obtained both for excited electrons and holes with energies up to 8 eV on a set of k vectors throughout the Brillouin zone (BZ). Strong localization effects in the calculated lifetimes are found. Averaged over the BZ inelastic lifetimes versus quasiparticle energy are reported as well. In addition, the effect of the spin-orbit induced splitting in the band structure on the calculated lifetimes in Pb is investigated.Comment: 10 pages, 8 figures, 5 table

Machine Learning Based Fall Detector with a Sensorized Tip

Fall detection has become an area of interest in recent years, as quick response to these events is critical to reduce the morbidity and mortality rate. In order to ensure proper fall detection, several technologies have been developed, including vision system, environmental detection systems, and wearable sensor based systems. However, in elderly or impaired people, it has been shown that the implementation of sensors in Assistive Devices for Walking, such as crutches or canes, can also be a promising alternative. In this work, a Support Vector Machine (SVM) based Fall Detection system is proposed, which uses the data provided by a Sensorized Tip which can be attached to different Assistive Devices for Walking (ADW). Unlike other approaches, the developed one is able to differentiate the fall of the ADW from the fall of the user. For that purpose, the developed Fall Detector uses two modules connected in series. The first one detects all falls, while the second differentiates between user and ADW falls. The proposed approach is validated in a set of experimental tests carried out by healthy volunteers that have simulated different falls. In addition, a comparative analysis is carried out by comparing the performance of the Sensorized Tip based Fall Detector and a state-of-the-art commercial accelerometer system. Results demonstrate that the proposed approach provides high Fall Detection Ratios (over 90%), similar or higher to wearable-sensor based approaches

Exchange interaction and its tuning in magnetic binary chalcogenides

Using a first-principles Green's function approach we study magnetic properties of the magnetic binary chalcogenides Bi2Te3, Bi2Se3, and Sb2Te3. The magnetic coupling between transition-metal impurities is long-range, extends beyond a quintuple layer, and decreases with increasing number of d electrons per 3d atom. We find two main mechanisms for the magnetic interaction in these materials: the indirect exchange interaction mediated by free carriers and the indirect interaction between magnetic moments via chalcogen atoms. The calculated Curie temperatures of these systems are in good agreement with available experimental data. Our results provide deep insight into magnetic interactions in magnetic binary chalcogenides and open a way to design new materials for promising applications

Exchange interaction and its tuning in magnetic binary chalcogenides

Under the terms of the Creative Commons Attribution License 3.0 (CC-BY).-- et al.Using a first-principles Green's function approach we study magnetic properties of the magnetic binary tetradymite chalcogenides Bi2Se3, Bi2Te3, and Sb2Te3. The magnetic coupling between transition-metal impurities is long range, extends beyond a quintuple layer, and decreases with increasing number of d electrons per 3d atom. We find two main mechanisms for the magnetic interaction in these materials: the indirect exchange interaction mediated by free carriers and the indirect interaction between magnetic moments via chalcogen atoms. The calculated Curie temperatures of these systems are in good agreement with available experimental data. Our results provide deep insight into exchange interactions in magnetic binary tetradymite chalcogenides and open a way to design new materials for promising applications.We acknowledge support by the Tomsk State University Competitiveness Improvement Program and the Deutsche Forschungsgemeinschaft (Priority Program SPP 1666 “Topological Insulators”).Peer Reviewe

Enhancement of tribological behavior of rolling bearings by applying a multilayer ZrN/ZrCN coating

This paper focuses on the tribological behaviour of ZrN/ZrCN coating on bearing steel substrates DIN 17230, 100Cr6/1.3505. Coatings are applied at room temperature processes by means of Cathodic Arc Evaporation (CAE), a kind of Physical Vapor Deposition (PVD) technique. In order to achieve a satisfactory compromise between coating-substrate adhesion and the surface roughness requirement of the bearing rings, a polish post-processing is proposed. Different polish post-processing times and conditions are applied. The coated and polished bearing rings are tested under real friction torque test protocols. These tests show that the application of the coating does not entail a significant improvement in friction performance of the bearing. However, fatigue tests in real test bench are pending to evaluate the possible improvement in bearing life time

Resiliencia de jóvenes deportistas en función del carácter individual o colectivo de su práctica

The objective of this study was to determine the levels of resilience with its two dimensions, “acceptance of self and life" (AUM) and "individual competence" (CP), in individual and collective sports participants. Comparisons depending on competitive level and sex, as well as, intragroup and intergroup comparisons were performed. A total of 435 athletes (300 men and 135 women) completed a socio-demographic questionnaire and the Resilience Scale (Wagnild and Young, 1993). The results indicate that those who practise individual sports obtain average values of resilience and the CP dimension higher than those obtained by athletes who do so collectively (p < 0.005). According to sex, in the AUM dimension, girls have lower averages than boys (p< 0.005). As for the competitive level, the trend is that at a higher competitive level, higher average resilience score (p < 0.05). The results draw the image of the athlete resilient as a young boy practicing sport of individual character and high level competitive.El objetivo de este estudio fue determinar los niveles de resiliencia con sus dos dimensiones, “Aceptación de uno mismo y de la vida” (AUM) y “Competencia Personal” (CP),en participantes de deportes de carácter individual y colectivo. Se realizaron comparaciones inter e intragrupo y en función del nivel competitivo y sexo. Un total de 435 deportistas (300 hombres y 135 mujeres) cumplimentaron un cuestionario socio-demográfico y La Escala de Resiliencia (Wagnild y Young, 1993). Los resultados señalan que quienes practican deportes de carácter individual obtienen valores medios de resiliencia y de la dimensión CP superiores a los obtenidos por deportistas que lo hacen de forma colectiva (p<0.005). Respecto al sexo, en la dimensión AUM, las chicas presentan medias menores que los chicos (p<0.005). En cuanto al nivel competitivo, la tendencia es que a mayor nivel competitivo, mayor puntuación media de resiliencia (p<0.05).Los resultados dibujan la imagen del deportista resiliente como un chico joven  practicante de deporte de carácter individual y de alto nivel competitivo

L1 transfer in the acquisition of manner and path in Spanish by native speakers of English

In this article the authors argue that L1 transfer from English is not only important in the early stages of L2 acquisition of Spanish, but remains influential in later stages if there is not enough positive evidence for the learners to progress in their development (Lefebvre, White, & Jourdan, 2006). The findings are based on analyses of path and manner of movement in stories told by British students of Spanish (N = 68) of three different proficiency levels. Verbs that conflate motion and path, on the one hand, are mastered early, possibly because the existence of Latinate path verbs, such as enter and ascend in English, facilitate their early acquisition by British learners of Spanish. Contrary to the findings of Cadierno (2004) and Cadierno and Ruiz (2006), the encoding of manner, in particular in boundary crossing contexts, seems to pose enormous difficulties, even among students who had been abroad on a placement in a Spanish-speaking country prior to the data collection. An analysis of the frequency of manner verbs in Spanish corpora shows that one of the key reasons why students struggle with manner is that manner verbs are so infrequent in Spanish. The authors claim that scarce positive evidence in the language exposed to and little or no negative evidence are responsible for the long-lasting effect of transfer on the expression of manner