Sperm trajectories form chiral ribbons.

We report the discovery of an entirely new three-dimensional (3D) swimming pattern observed in human and horse sperms. This motion is in the form of 'chiral ribbons', where the planar swing of the sperm head occurs on an osculating plane creating in some cases a helical ribbon and in some others a twisted ribbon. The latter, i.e., the twisted ribbon trajectory, also defines a minimal surface, exhibiting zero mean curvature for all the points on its surface. These chiral ribbon swimming patterns cannot be represented or understood by already known patterns of sperms or other micro-swimmers. The discovery of these unique patterns is enabled by holographic on-chip imaging of >33,700 sperm trajectories at >90-140 frames/sec, which revealed that only ~1.7% of human sperms exhibit chiral ribbons, whereas it increases to ~27.3% for horse sperms. These results might shed more light onto the statistics and biophysics of various micro-swimmers' 3D motion

Smart Fabric sensors for foot motion monitoring

Smart Fabrics or fabrics that have the characteristics of sensors are a wide and emerging field of study. This thesis summarizes an investigation into the development of fabric sensors for use in sensorized socks that can be used to gather real time information about the foot such as gait features. Conventional technologies usually provide 2D information about the foot. Sensorized socks are able to provide angular data in which foot angles are correlated to the output from the sensor enabling 3D monitoring of foot position. Current angle detection mechanisms are mainly heavy and cumbersome; the sensorized socks are not only portable but also non-invasive to the subject who wears them. The incorporation of wireless features into the sensorized socks enabled a remote monitoring of the foot

Learning from Nature: Unsteady Flow Physics in Bioinspired Flapping Flight

There are few studies on wing flexibility and the associated aerodynamic performance of insect wings during free flight, which are potential candidates for developing bioinspired microaerial vehicles (MAVs). To this end, this chapter aims at understanding wing deformation and motions of insects through a combined experimental and computational approach. Two sets of techniques are currently being developed to make this integration possible: first, data acquisition through the use of high-speed photogrammetry and accurate data reconstruction to quantify the wing and body motions in free flight with great detail and second, direct numerical simulation (DNS) for force measurements and visualization of vortex structures. Unlike most previous studies that focus on the near-field vortex formation mechanisms of a single rigid flapping wing, this chapter presents freely flying insects with full-field vortex structures and associated unsteady aerodynamics at low Reynolds numbers. Our chapter is expected to lead to valuable insights into the underlying physics about flow mechanisms of low Reynolds number flight in nature, which will have great significance to flapping-wing MAV design and optimization research in the future

Capturing Hands in Action using Discriminative Salient Points and Physics Simulation

Hand motion capture is a popular research field, recently gaining more attention due to the ubiquity of RGB-D sensors. However, even most recent approaches focus on the case of a single isolated hand. In this work, we focus on hands that interact with other hands or objects and present a framework that successfully captures motion in such interaction scenarios for both rigid and articulated objects. Our framework combines a generative model with discriminatively trained salient points to achieve a low tracking error and with collision detection and physics simulation to achieve physically plausible estimates even in case of occlusions and missing visual data. Since all components are unified in a single objective function which is almost everywhere differentiable, it can be optimized with standard optimization techniques. Our approach works for monocular RGB-D sequences as well as setups with multiple synchronized RGB cameras. For a qualitative and quantitative evaluation, we captured 29 sequences with a large variety of interactions and up to 150 degrees of freedom.Comment: Accepted for publication by the International Journal of Computer Vision (IJCV) on 16.02.2016 (submitted on 17.10.14). A combination into a single framework of an ECCV'12 multicamera-RGB and a monocular-RGBD GCPR'14 hand tracking paper with several extensions, additional experiments and detail

Estimation of skeletal kinematics in freely moving rodents

Forming a complete picture of the relationship between neural activity and skeletal kinematics requires quantification of skeletal joint biomechanics during free behavior; however, without detailed knowledge of the underlying skeletal motion, inferring limb kinematics using surface-tracking approaches is difficult, especially for animals where the relationship between the surface and underlying skeleton changes during motion. Here we developed a videography-based method enabling detailed three-dimensional kinematic quantification of an anatomically defined skeleton in untethered freely behaving rats and mice. This skeleton-based model was constrained using anatomical principles and joint motion limits and provided skeletal pose estimates for a range of body sizes, even when limbs were occluded. Model-inferred limb positions and joint kinematics during gait and gap-crossing behaviors were verified by direct measurement of either limb placement or limb kinematics using inertial measurement units. Together we show that complex decision-making behaviors can be accurately reconstructed at the level of skeletal kinematics using our anatomically constrained model

Video Kinematic Evaluation: new insights on the cardiac mechanical function

The cardiac mechanical function plays a critical role in governing and regulating its performance under both normal and pathological conditions. The left ventricle has historically received more attention in both congenital and acquired heart diseases and was considered as the mainstay of normal hemodynamics. However, over the past few decades, there has been increasing recognition of the pivotal role of the right ventricle in determining functional performance status and prognosis in multiple conditions. Nonetheless, the ventricles should not be considered separately as they share the septum, are encircled with common myocardial fibers and are surrounded by the pericardium. Thus, changes in the filling of one ventricle may alter the mechanical function of its counterpart. This ventricular interdependence remains even after the removal of the pericardium because of constrictive pericarditis or during open chest surgery. Interestingly, during open chest surgery, only the right ventricle mechanical activity is visually checked by the surgeon and cardiologist due to the absence of an intraoperative imaging technique able to evaluate its complex function. Noteworthy, most of the imaging techniques available to clinicians are established for the assessment of the left ventricle, with the ejection fraction being the most used parameter. However, this value is a measure of global systolic function which comes short in identifying regional myocardial impairment and the mechanical contraction. Therefore, new approaches are needed to deeply investigate the mechanics of both ventricles and correctly assess the cardiac mechanical performance. In this thesis, I studied the mechanical function of the left ventricle through different modalities of cardiac magnetic resonance and employed an innovative imaging technique for the assessment of the right ventricle mechanical function during open chest surgery

Tongue Movements in Feeding and Speech

The position of the tongue relative to the upper and lower jaws is regulated in part by the position of the hyoid bone, which, with the anterior and posterior suprahyoid muscles, controls the angulation and length of the floor of the mouth on which the tongue body \u27rides\u27. The instantaneous shape of the tongue is controlled by the \u27extrinsic muscles \u27 acting in concert with the \u27intrinsic \u27 muscles. Recent anatomical research in non-human mammals has shown that the intrinsic muscles can best be regarded as a \u27laminated segmental system \u27 with tightly packed layers of the \u27transverse\u27, \u27longitudinal\u27, and \u27vertical\u27 muscle fibers. Each segment receives separate innervation from branches of the hypoglosssal nerve. These new anatomical findings are contributing to the development of functional models of the tongue, many based on increasingly refined finite element modeling techniques. They also begin to explain the observed behavior of the jaw-hyoid-tongue complex, or the hyomandibular \u27kinetic chain\u27, in feeding and consecutive speech. Similarly, major efforts, involving many imaging techniques (cinefluorography, ultrasound, electro-palatography, NMRI, and others), have examined the spatial and temporal relationships of the tongue surface in sound production. The feeding literature shows localized tongue-surface change as the process progresses. The speech literature shows extensive change in tongue shape between classes of vowels and consonants. Although there is a fundamental dichotomy between the referential framework and the methodological approach to studies of the orofacial complex in feeding and speech, it is clear that many of the shapes adopted by the tongue in speaking are seen in feeding. It is suggested that the range of shapes used in feeding is the matrix for both behaviors