Microsaccadic Fixational Eye Movements as an Oculomotor Marker for Concussion

ObjectiveTo identify whether concussion causes abnormalities in fixational eye movements, specifically the generation of microsaccades.BackgroundMicrosaccades are microscopic rapid eye movements that occur normally with attempted fixation. However, changes in microsaccade rate, magnitude, etc have been linked with neurologic and ophthalmic pathologies.Design/MethodsWe collected baseline data for college athletes (n = 116) at Sterling College (Sterling, KS) as they reported for the physical examination before the beginning of the athletic season. None of the athletes had a prior history of concussion. Concussion patients (n = 86) were selected from patients who had an initial visit for concussion at a private concussion clinic. Patients were included if they presented within 50 days of injury. All participants were between 18 and 23 years of age. For each participant we measured the number of saccades generated, the size and speed of the micro saccades, the area covered and the ratio of vertical-to-horizontal direction component of the fixational eye movements, using a 250 Hz video-eye tracker mounted inside a HTC Vive VR headset. Participants were instructed to fixate on a central dot for 140 seconds, in 20-second intervals. We performed a logistic regression with the log-transformed oculomotor characteristics as independent variables and concussion yes/no as dependent variables. Errors are presented as standard error from the mean.ResultsThe average microsaccade magnitude was higher in concussed than in non-concussed participants (1.85 ± 0.12° vs 1.32 ± 0.06°, p < 0.001). Similarly, the fixational eye movements (microsaccades + drifts) of concussed patients tended to cover a more vertical area during fixation periods (vertical-to-horizontal ratio of 3.49 ± 0.94 vs 1.12 ± 0.04, p < 0.005).ConclusionsOculomotor testing, specifically microsaccades is a potential marker for concussion. Concussion patients present larger and more vertical eye movements during fixation.

Wind Intensity and Power Density in the Brazilian Dry Tropical Forests (Caatinga)

Wind speed has been widely used for energy purposes. Therefore, studies focused on its knowledge are extremely relevant to better benefit from this resource. The aim of this study is to analyze wind behavior and estimate wind power density (WPD) in the interior of northeastern Brazil, a region with predominance of the semi-arid climate, based on the data made available by the automatic station installed at the Experimental Farm in the municipality of São João do Cariri-PB, which come from the SONDA project and refer to the year 2007. Descriptive analysis techniques were used to identify the periods in which the wind behavior is more favorable to wind harnessing. From the results obtained, there was a predominance of southeast in the wind direction component. However, the values of both the observed wind speed (2, 25 and 50 m) and the wind speed estimated for the levels of 100 and 150 m, as well as the estimates of power density (50, 100 and 150 m) showed that the lowest records are present mainly in the first hours of the day, as well as in the first half of the year, while the highest values occur from 10 a.m. extending to the beginning of the night and prevail in the last six months of the year. These determinations denoted higher values of wind power density available for the second half of the year (mainly from August to December).

Prediction and Measurement of Quenching and Pre-Stretching Stress in 7050 Aluminum Alloy Thick Plate

The article established a modelling that predicted and measured the quenching and pre-stretching stress in 7050 aluminum alloy thick plate in order to make the alloy suitable enough for manufacturing in the aerospace industries. The results show that both the rolling direction component stress and the transverse direction component stress have a “M” distribution along the plate thickness of 7050 aluminum alloy thick plate, but the level is slightly different, but the level is slightly different. The maximum value of quenching residual stress is about 187MPa in the 80mm thick of 7050 plate. Pre-stretching of the heat treated and quenched alloy to 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0% and 3.5% to reduce the residual stresses. It has been recorded that more than 90% reduction of residual stresses were observed in a pre-stretching rage of 2-3%. Measuring the surface residual stresses of the alloy by ultrasonic methods and measuring the internal residual stresses of the alloy by crack compliance methods. The two methods are used to verify the model. The difference between the measurement and the simulation is within 40MPa. The experimental data of the ultrasonic and the crack compliance methods were found to correspond well with the simulated models. This shows that the simulation model can effectively predict the evolution of residual stress in 7050 aluminum alloy thick plate, and the simulation model can also be reconstructed and inspected through the experimentally measurement.

Design and Analysis of a High Efficient Multi-Segment Redundancy Linear Motor

Background: The electromagnetic aircraft launch system is used to assists the carrier aircraft to accelerate takeoff on a short distance on the flight deck. Linear motors are required to have high efficiency and thrust / volume ratio, as the actuator of the EMALS. In addition, linear motors were required have the fluctuation of the thrust is as small as possible to prevent impact and overstress on the airborne equipment. The thrust performance and thrust fluctuation suppression of linear motors are the current research hotspots in the field of EMALS. Objective: To improve the efficiency of the system, this paper proposes a multi-segment LPMSM. Methods: We design a decentralized primary structure based on the Autonomous Decentralized System (ADS) concept. Only the coils near the moving secondary are motivated during the launch process, the others could be released from being driven after the secondary slide over; this control will save the waste of energy. Results: A multi-segment linear motor is proposed to improve the efficiency of the EMALS. This motor consists of two sections - the one with iron core for the low speed process and the one without iron core for the high speed process. Conclusion: The normal direction component of the air gap magnetic flux density is much larger than that of the longitudinal component, and their values are 80-90% and 10-20% respectively. For the normal direction component, it is mainly affected by the third, seventh, and ninth harmonics. The accelerating and energy test results show that, in the accelerating process, the efficiency of the linear motor can be more than 90%, and the acceleration is stable.

The influence of the ratio between the wire and process velocities on the wetting process during laser brazing

Laser brazing is used in automotive production for the joining of car body parts with customer-visible seams, whereby the highest optical seam quality is demanded. During the wetting process, a constriction formation can occur within the molten brazing material, which subsequently collapses; this induces a stepwise progression of the wetting front, thereby decreasing the optical seam quality. The aim of this study is to investigate the influence of the wire and process velocities on this constriction formation. For this purpose, high-speed recordings of the process zone are performed during laser brazing and then evaluated concerning the wetting process. The results show that the constriction formation depends on the relationship between the process velocity and the process direction component of the wire velocity. The constriction formation only occurs when the process velocity exceeds the parallel-oriented component of the wire velocity. This constriction formation is unstable and collapses repeatedly. In this study, increasing velocity differences stabilizes the constriction existence. This stabilization correlates with a uniform wetting process and a reduced frequency of the occurrence of blowout events, probably due to improved outgassing of zinc bubbles from the melt pool.

An Improved Point Cloud Descriptor for Vision Based Robotic Grasping System

In this paper, a novel global point cloud descriptor is proposed for reliable object recognition and pose estimation, which can be effectively applied to robot grasping operation. The viewpoint feature histogram (VFH) is widely used in three-dimensional (3D) object recognition and pose estimation in real scene obtained by depth sensor because of its recognition performance and computational efficiency. However, when the object has a mirrored structure, it is often difficult to distinguish the mirrored poses relative to the viewpoint using VFH. In order to solve this difficulty, this study presents an improved feature descriptor named orthogonal viewpoint feature histogram (OVFH), which contains two components: a surface shape component and an improved viewpoint direction component. The improved viewpoint component is calculated by the orthogonal vector of the viewpoint direction, which is obtained based on the reference frame estimated for the entire point cloud. The evaluation of OVFH using a publicly available data set indicates that it enhances the ability to distinguish between mirrored poses while ensuring object recognition performance. The proposed method uses OVFH to recognize and register objects in the database and obtains precise poses by using the iterative closest point (ICP) algorithm. The experimental results show that the proposed approach can be effectively applied to guide the robot to grasp objects with mirrored poses.

Effect of Slab Centerline Segregation on DWTT Properties of 22mm Thick X80M Hot Rolled Steel Strip

The replacement of 22mm thick X80M hot rolled strip for the traditional heavy plate production technology has remarkable advantages in improving the yield, reducing the cost of manufacturing and improving the outer diameter adjustment of pipeline. Low temperature anti Drop Weight Tear Test (for short DWTT) performs one of the key research problems of 2250mm hot rolling line production of this specification. Aiming at the problem of the substandard performance of rolled DWTT development process, the slab fracture morphology of different proportion and slab thickness direction component segregation degree of system were analyzed through the electron microscope. The results showed that the thickness of steel strip was serious segregation and is the main factor affecting the performance of DWTT. By optimizing the caster arc alignment and secondary cooling water, then improving the central segregation effect, the performance of DWTT can be effectively improved, and a stable development and production of 22mm thickness X80M pipeline steel hot rolledstrip can be achieved.

Shear-induced diffusion of red blood cells in a semi-dilute suspension

The diffusion of red blood cells (RBCs) in blood is important to the physiology and pathology of the cardiovascular system. In this study, we investigate flow-induced diffusion of RBCs in a semi-dilute system by calculating the pairwise interactions between RBCs in simple shear flow. A capsule with a hyperelastic membrane was used to model an RBC. Its deformation was resolved using the finite element method, whereas fluid motion inside and outside the RBC was solved using the boundary element method. The results show that shear-induced RBC diffusion is significantly anisotropic, i.e. the velocity gradient direction component is larger than the vorticity direction. We also found that the motion of RBCs during the interaction is strongly dependent on the viscosity ratio of the internal to external fluid, and the diffusivity decreases monotonically as the viscosity ratio increases. The scaling argument also suggests that the diffusivity is proportional to the shear rate and haematocrit, if the suspension is in a semi-dilute environment and the capillary number is invariant. These fundamental findings are useful to understand transport phenomena in blood flow.

DInSAR Coseismic Deformation of the May 2011 M_w 5.1 Lorca Earthquake (southeastern Spain)

The coseismic superficial deformation at the region of Lorca (Murcia, southeastern Spain) due to the Mw 5.1 earthquake on 11 May 2011 was characterized by a multidisciplinary team, integrating information from DInSAR, GPS and numerical modelling techniques. Despite the moderate magnitude of the event, quantitative information was obtained from the interferometric study of a pair of TerraSAR-X images. The DinSAR results defined the trace of the fault plane and evidenced uplift of the hanging wall block in agreement with the estimated deformation obtained through an elastic rupture dislocation numerical model. Meanwhile for the footwall block, interferometric results showed that tectonic deformation is masked by an important subsidence related to groundwater extraction previously identified at the area of study. Horizontal crustal deformation rates and velocity vectors, obtained from GPS stations existent at the area, were also coherent with the tectonic setting of the southern margin of the Iberian Peninsula and with the focal mechanism calculated for the Lorca event. The analysis of a continuous GPS site in Lorca showed good agreement with the horizontal N–S direction component relative to the numerical model and tectonics of the region. This is the first time at this seismic active area that a multi-technique analysis has been performed immediately after the occurrence of a seismic event, comparing the existing deformation data with a theoretical numerical model based on estimated seismic rupture dislocation.