RIDI: Robust IMU Double Integration

This paper proposes a novel data-driven approach for inertial navigation, which learns to estimate trajectories of natural human motions just from an inertial measurement unit (IMU) in every smartphone. The key observation is that human motions are repetitive and consist of a few major modes (e.g., standing, walking, or turning). Our algorithm regresses a velocity vector from the history of linear accelerations and angular velocities, then corrects low-frequency bias in the linear accelerations, which are integrated twice to estimate positions. We have acquired training data with ground-truth motions across multiple human subjects and multiple phone placements (e.g., in a bag or a hand). The qualitatively and quantitatively evaluations have demonstrated that our algorithm has surprisingly shown comparable results to full Visual Inertial navigation. To our knowledge, this paper is the first to integrate sophisticated machine learning techniques with inertial navigation, potentially opening up a new line of research in the domain of data-driven inertial navigation. We will publicly share our code and data to facilitate further research

Influencia de la naturaleza de las partículas de proyección en el proceso de shot peening en la mejora de la osteointegración de implantes dentales.

El presente trabajo se ha centrado en valorar el efecto que tiene sobre las características superficiales, tratar la superficie de discos de Ti C. P., mediante un shot peening con distintos tipos de partículas de proyección: AL2O2, TiO2 y SiC. También se ha determinado la influencia que tiene pasivar los discos tratados con SiC, con HCl o con HF/HNO3; sobre todo desde el punto de vista de la limpieza superficial después del tratamiento, ya que se pretende aprovechar la reacción química que se produce entre el SiC y el HF, con la formación de SiF4. Para todo ello se han efectuado ensayos de la rugosidad superficial de los discos después del shot peening; tanto cuantitativos como cualitativos. Así mismo se ha determinado la capacidad de la partícula de soportar el shot peening sin perder su característica más importante dentro del proceso: su tamaño inicial. Finalmente, se ha propuesto un proceso de fabricación de partículas de TiO2 por sinterización. La fabricación en el laboratorio ha sido necesaria debido a la imposibilidad de encontrar en el mercado las partículas de esta naturaleza.Peer Reviewe

Relation of surface and underground waters in Chungará and Cotacotani lake districts, northern Chile: an isotopic study.

Lake Chungará and Cotacotani lake districts are surface water bodies located to the northwest of Lauca Basin in the northern Chilean Altiplano. Surface and underground waters show low to moderate saline content and an electrical conductivity in the range of 48.7 to 3090 μS/cm. The lakes are related to a system of aquifers on the nearby volcano flanks and debris avalanche deposits of Parinacota volcano. On the basis of δ18O and δD isotopic composition and its correlation with the chloride content in Chungará and Cotacotani lake, spring, and Chungará river waters it is demonstrated that: a. Lake Chungará's waters show vertical and horizontal homogeneous isotopic composition, which indicates a good mixture of waters in the lake; b. an important part of the Cotacotani lake recharge feeding come from Lake Chungará, that flows laterally as groundwater; c. the groundwater that feeds the springs of the area has its main recharge in the spring-summer (October-March) precipitation. The high content of tritium (3H) measured in spring waters of the area suggested a very recent recharge (last decades) of the aquifer system. The application of lumped parameter models to interpret the water residence time in the aquifer indicates that the piston flow model shows the best fit to the isotopic composition of Chungará-Cotacotani groundwater

A supramodal role of the basal ganglia in memory and motor inhibition: Meta-analytic evidence

© 2017 The Authors The ability to stop actions and thoughts is essential for goal-directed behaviour. Neuroimaging research has revealed that stopping actions and thoughts engage similar cortical mechanisms, including the ventro- and dorso-lateral prefrontal cortex. However, whether and how these abilities require similar subcortical mechanisms remains unexplored. Specifically of interest are the basal ganglia, subcortical structures long-known for their motor functions, but less so for their role in cognition. To investigate the potential common mechanisms in the basal ganglia underlying action and thought stopping, we conducted meta-analyses using fMRI data from the Go/No-Go, Stop-signal, and Think/No-Think tasks. All three tasks require active stopping of prepotent actions or thoughts. To localise basal ganglia activations, we performed high-resolution manual segmentations of striatal subregions. We found that all three tasks recovered clusters in the basal ganglia, although the specific localisation of these clusters differed. Although the Go/No-Go and Stop-signal tasks are often interchangeably used for measuring action stopping, their cluster locations in the basal ganglia did not significantly overlap. These different localised clusters suggest that the Go/No-Go and Stop-signal tasks may recruit distinct basal ganglia stopping processes, and therefore should not be treated equivalently. More importantly, the basal ganglia cluster recovered from the Think/No-Think task largely co-localised with that from the Stop-signal task, but not the Go/No-Go task, possibly indicating that the Think/No-Think and Stop-signal tasks share a common striatal circuitry involved in the cancellation of unwanted thoughts and actions. The greater similarity of the Think/No-Think task to the Stop-Signal rather than Go/No-Go task also was echoed at the cortical level, which revealed highly overlapping and largely right lateralized set of regions including the anterior DLPFC, VLPFC, Pre-SMA and ACC. Overall, we provide novel evidence suggesting not only that the basal ganglia are critical for thought stopping, but also that they are involved in specific stopping subprocesses that can be engaged by tasks in different domains. These findings raise the possibility that the basal ganglia may be part of a supramodal network responsible for stopping unwanted processes more broadly

Topological phase transitions between chiral and helical spin textures in a lattice with spin-orbit coupling and a magnetic field

We consider the combined effects of large spin-orbit couplings and a perpendicular magnetic field in a 2D honeycomb fermionic lattice. This system provides an elegant setup to generate versatile spin textures propagating along the edge of a sample. The spin-orbit coupling is shown to induce topological phase transitions between a helical quantum spin Hall phase and a chiral spin-imbalanced quantum Hall state. Besides, we find that the spin orientation of a single topological edge state can be tuned by a Rashba spin-orbit coupling, opening an interesting route towards quantum spin manipulation. We discuss the possible realization of our results using cold atoms trapped in optical lattices, where large synthetic magnetic fields and spin-orbit couplings can be engineered and finely tuned. In particular, this system would lead to the observation of a time-reversal-symmetry-broken quantum spin Hall phase.Comment: 8 pages, 3 figures, Accepted in Europhys. Lett. (Dec 2011

Giant barocaloric effect in all-d-metal Heusler shape memory alloys

We have studied the barocaloric properties associated with the martensitic transition of a shape memory Heulser alloy Ni50Mn31.5Ti18.5 which is composed of all-d-metal elements. The composition of the sample has been tailored to avoid long range ferromagnetic order in both ausenite and martensite. The lack of ferromagnetism results in a weak magnetic contribution to the total entropy change thereby leading to a large transition entropy change. The combination of such a large entropy change and a relatively large volume change at the martensitic transition gives rise to giant barocaloric properties in this alloy. When compared to other shape memory Heusler alloys, our material exhibits values for adiabatic temperature and isothermal entropy changes significantly larger than values reported so far for this class of materials. Furthermore, our Ni50Mn31.5Ti18.5 also compares favourably to the best state-of-the-art magnetic barocaloric materials.Peer ReviewedPostprint (author's final draft

Influencia del proceso de esterilización en la mojabilidad del titanio modificado superficialmente

El objetivo de este trabajo es estudiar el cambio en las propiedades energéticas de muestras de titanio comercialmente puro debido a distintos tratamientos superficiales y a distintos métodos de esterilización; con la finalidad de entender cómo afectan estos cambios a los procesos biológicos de los implantes de titanio. Los distintos tratamientos superficiales utilizados fueron: la formación de rugosidad mediante la proyección de partículas abrasivas, el granallado, y la esterilización mediante autoclave, óxido de etileno o radiación gamma. Tanto el nivel de rugosidad generada como la naturaleza de las partículas del granallado influyen en el carácter energético de las muestras; incrementando el carácter hidrofóbico con el aumento de la rugosidad y con la utilización de alúmina. Los contaminantes debidos al proceso de autoclave hidrofobizan las superficies; contrariamente a la esterilización por óxido de etileno que disminuye el valor del ángulo de contacto. La modificación de las superficies tratadas fue examinada con una serie de técnicas analíticas superficiales que incluyen el microscopio electrónico de barrido (SEM), la interferometría óptica y la medición del ángulo de contacto para poder realizar una caracterización topográfica, cualitativa y cuantitiva, y una caracterización energética, respectivamente.The aim of this work is to study the energetic properties of commercially pure titanium samples due to different surface treatments and different sterilization methods; with the purpose to understand how these changes affect to the biological processes of titanium implants. The different surface treatments were: roughness obtained by shot blasting, and sterilization by steam autoclaving, ethylene oxide or gamma radiation. Roughness level and the nature of the abrasive particles of shot blasting influence energetically the samples; increasing the hydrophobic behaviour with the increase of the surface roughness and the alumina use. The contamination due to steam autoclaving hydrophobizes the surface; contrary to sterilization by ethylene oxide, which reduces the contact angle value. The modification of treated surfaces was examined with a series of surface analytical techniques that include the scanning electron microscopy (SEM), the white light interferometer microscopy and the static contact angle measurement in order to determine a qualitative and quantitative topographic characterization and an energetic characterization