Using accelerometer and GPS data for real-life physical activity type detection

This paper aims to examine the role of global positioning system (GPS) sensor data in real-life physical activity (PA) type detection. Thirty-three young participants wore devices including GPS and accelerometer sensors on five body positions and performed daily PAs in two protocols, namely semi-structured and real-life. One general random forest (RF) model integrating data from all sensors and five individual RF models using data from each sensor position were trained using semi-structured (Scenario 1) and combined (semi-structured + real-life) data (Scenario 2). The results showed that in general, adding GPS features (speed and elevation difference) to accelerometer data improves classification performance particularly for detecting non-level and level walking. Assessing the transferability of the models on real-life data showed that models from Scenario 2 are strongly transferable, particularly when adding GPS data to the training data. Comparing individual models indicated that knee-models provide comparable classification performance (above 80%) to general models in both scenarios. In conclusion, adding GPS data improves real-life PA type classification performance if combined data are used for training the model. Moreover, the knee-model provides the minimal device configuration with reliable accuracy for detecting real-life PA types

Comparing fracture resistance of endodontically treated teeth using different preparation-obturation combinations

Background: One of the main reasons for extraction of endodontically treated teeth is vertical root fracture (VRF). Some factors such as root canal treatment are involved in vertical root fracture because of their potential to weaken the tooth structure. Therefore, this study aimed to investigate the effect of combining different obturation materials and rotary systems on the fracture resistance of treated teeth. Methods: Eighty extracted maxillary central incisors were selected. The coronal portions of all teeth were removed at the cemento-enamel junction leaving the root segment of nearly 13 mm length. Roots were randomly divided into 2 groups according to the system used in root canal preparations, Group I: ProTaper, Group Π: Wave 1. Each main group was further subdivided into 2 equal subgroups according to the obturation system being used, Subgroup A: ProTaper, AH26 obturator, Subgroup B: ProTaper, Bioceramic, Subgroup C: Wave 1, AH26 obturator and Subgroup D: Wave 1, Bioceramic. Fracture resistance of each sample was measured by loading in universal testing machine. The results were analyzed with two- way ANOVA followed by multiple comparison Tukey HSD test. Results: The highest mean fracture resistance value (256.7N) was associated with Soft- Core/AH26 obturation and wave one (subgroup C), while the lowest value (239.8N) was for Bioceramic sealer and Wave 1 (subgroup D); however, there was no statistical significant difference (P>0.05) among all tested subgroups. Conclusion: All instrumentation techniques caused weakening of the root structure and made them susceptible to fiacture without any significant difference and therefore alternative strategies should be considered to reinforce endodontically treated roots. © 2019, Kerman University of Medical Sciences. All rights reserved

Comparative study of dimensional accuracy in three dental implant impression techniques: Open tray, closed tray with impression coping, and snap cap

Aim: Several impression techniques have been proposed to result passive fitness between the prosthesis and osseointegrated implant. The aim of the study was to compare dimensional accuracy of three impression methods: Open tray, closed tray with impression coping, and closed tray with snap cap. Materials and methods: In this experimental study, a mandibular acrylic model was prepared with a milling machine to place three holes for dental implant analogs (Dio SM) with the dimension of 3.8 � 10 mm into the intended sites (one in midline and two others on the side at a distance of 10 mm) parallel with each other and perpendicular to the plane. Twenty-seven casts were prepared with impression material of polyvinyl siloxane (PVS) and dental stone type IV and divided into three groups. Implant situations were measured by coordinate measuring machine (CMM) and results were analyzed with Kruskal-Wallis and Mann-Whitney test to perform pairwise comparison among the groups. Results: The mean �R values for open tray, closed tray with impression coping, and closed tray with snap cap were respectively, 0.070 ± 0.088, 0.173 ± 0.205, and 0.142 ± 0.044.There were statistically significant differences between open tray and closed tray as well as open tray and snap cap methods (p < 0.05), but there was no statistically significant difference between closed tray and snap cap method (p = 0.1). Conclusion: Regarding the results, open tray impression technique had the highest dimensional accuracy compared with the other two methods. There were no statically significant differences between closed tray with snap cap and closed tray with impression coping technique. Clinical significance: Snap cap technique is less time consuming with similar dimensional accuracy in comparison with open tray impression technique. © 2018 Jaypee Brothers Medical Publishers (P) Ltd

Monopoles and Holography

We present a holographic theory in AdS_4 whose zero temperature ground state develops a crystal structure, spontaneously breaking translational symmetry. The crystal is induced by a background magnetic field, but requires no chemical potential. This lattice arises from the existence of 't Hooft-Polyakov monopole solitons in the bulk which condense to form a classical object known as a monopole wall. In the infra-red, the magnetic field is screened and there is an emergent SU(2) global symmetry.Comment: 33 pages, 16 figures; v2: ref adde

Holographic Vitrification

We establish the existence of stable and metastable stationary black hole bound states at finite temperature and chemical potentials in global and planar four-dimensional asymptotically anti-de Sitter space. We determine a number of features of their holographic duals and argue they represent structural glasses. We map out their thermodynamic landscape in the probe approximation, and show their relaxation dynamics exhibits logarithmic aging, with aging rates determined by the distribution of barriers.Comment: 100 pages, 25 figure