Current deformation in Central Afar and triple junction kinematics deduced from GPS and InSAR measurements

Kinematics of divergent boundaries and Rift-Rift-Rift junctions are classically studied using long-term geodetic observations. Since significant magma-related displacements are expected, short-term deformation provides important constraints on the crustal mechanisms involved both in active rifting and in transfer of extensional deformation between spreading axes. Using InSAR and GPS data, we analyse the surface deformation in the whole Central Afar region in detail, focusing on both the extensional deformation across the Quaternary magmato-tectonic rift segments, and on the zones of deformation transfer between active segments and spreading axes. The largest deformation occurs across the two recently activated Asal-Ghoubbet (AG) and Manda Hararo-Dabbahu (MH-D) magmato-tectonic segments with very high strain rates, whereas the other Quaternary active segments do not concentrate any large strain, suggesting that these rifts are either sealed during interdyking periods or not mature enough to remain a plate boundary. Outside of these segments, the GPS horizontal velocity field shows a regular gradient following a clockwise rotation of the displacements from the Southeast to the East of Afar, with respect to Nubia. Very few shallow creeping structures can be identified as well in the InSAR data. However, using these data together with the strain rate tensor and the rotations rates deduced from GPS baselines, the present-day strain field over Central Afar is consistent with the main tectonic structures, and therefore with the long-term deformation. We investigate the current kinematics of the triple junction included in our GPS data set by building simple block models. The deformation in Central Afar can be described by adding a central microblock evolving separately from the three surrounding plates. In this model, the northern block boundary corresponds to a deep EW-trending trans-tensional dislocation, locked from the surface to 10–13 km and joining at depth the active spreading axes of the Red Sea and the Aden Ridge, from AG to MH-D rift segments. Over the long-term, this plate configuration could explain the presence of the en-échelon magmatic basins and subrifts. However, the transient behaviour of the spreading axes implies that the deformation in Central Afar evolves depending on the availability of magma supply within the well-established segments

Ranking and rating bicycle helmet safety performance in oblique impacts using eight different brain injury models

Bicycle helmets are shown to offer protection against head injuries. Rating methods and test standards are used to evaluate different helmet designs and safety performance. Both strain-based injury criteria obtained from finite element brain injury models and metrics derived from global kinematic responses can be used to evaluate helmet safety performance. Little is known about how different injury models or injury metrics would rank and rate different helmets. The objective of this study was to determine how eight brain models and eight metrics based on global kinematics rank and rate a large number of bicycle helmets (n=17) subjected to oblique impacts. The results showed that the ranking and rating are influenced by the choice of model and metric. Kendall’s tau varied between 0.50 and 0.95 when the ranking was based on maximum principal strain from brain models. One specific helmet was rated as 2-star when using one brain model but as 4-star by another model. This could cause confusion for consumers rather than inform them of the relative safety performance of a helmet. Therefore, we suggest that the biomechanics community should create a norm or recommendation for future ranking and rating methods

Effect of Election Preferences on the Stock Prices

There exist a lot of empirical researches, that examine what factors effect the stock market volatility. The concept of investor sentiment is quite popular and is frequently discussed. However, there does not exist any research which would study the relation between the change in election preferences during the presidential campaigns and stock market volatility. The present thesis explores the effect of political sentiment on United States and French models. Here, we construct the model, which examines the effect of change in election preferences on the volatility. The results suggest, that change in election preferences does not affect the stock market volatility during the presidential campaign. Thus, its inclusion to the model does not increase the prediction power

Development of Haptic Approaches for a Head-Controlled Soft Robotic Endoscope

Recent advances in soft robotics are utilized to solve challenges in endoscopy, such as maneuverability, flexibility, and the structural stiffness required to deliver enough force during endoscopic surgical procedure. Other major challenge is the lack of haptic feedback from the tool end-effector to the surgeon. Current clinical practice in minimally invasive intervention requires an assistant to control the camera since the surgeon is preoccupied with task at hand, creating a indirect control procedure for maneuvering the endoscope. For the soft robotic endoscope, we implemented a haptic feedback interface along with a novel control method to concurrently tackle these challenges. The user of the developed system can visualise the planned 2D insertion path and steer the endoscope module accordingly using an inertial measurement unit mounted on a head-band. Furthermore, five different haptic feedback methods (three kinesthetic and two vibrotactile) were compared in term of user accuracy while steering the endoscope along a planned path. The results show that the user's accuracy using kinesthetic and vibrotactile feedback were comparable, however, participants of this study find vibrotactile feedback approach more preferable for its intuitiveness and comfort

Experimental Evaluation Using Head Motion and Augmented Reality to Intuitively Control a Flexible Endoscope

Thoracoscopic procedures require an assistant to hold and control the camera while the surgeon performs the surgical task. This paper presents an approach in which surgeons can control camera orientation using their head movements, allowing them to steer a flexible endoscope without the need for a camera assistant during the operation. Additionally, an augmented reality headset has been integrated into the head movement control system to serve as a virtual display monitor capable of following the user's gaze. Experiments were conducted to assess the feasibility of the head-controlled approach compared to the manual control method by conducting camerapointing experiments performed by clinicians and trained nonclinician participants at two difficulty levels. The results from the camera-pointing experiments have shown that the developed head-controlled endoscope has a statistically faster reaching time performance compared to manual use of the flexible endoscope in high difficulty index tasks with clinician participants (p=0.04), and in both lower and high difficulty index tasks with non-clinician participants (p=0.03). The head-controlled robotic endoscope approach enables surgeons to intuitively control the camera during an operation, while simultaneously performing other tasks using their hands, without sacrificing camera steering accuracy