Auditory Subjective-Straight-Ahead Blurs during Significantly Slow Passive Body Rotation

This paper reports on the deterioration in sound-localization accuracy during listeners’ head and body movements. We investigated the sound-localization accuracy during passive body rotations at speeds in the range of 0.625–5 °/s. Participants were asked to determine whether a 30-ms noise stimuli emerged relative to their subjective-straight-ahead reference. Results indicated that the sound-localization resolution degraded with passive rotation, irrespective of the rotation speed, even at speeds of 0.625 °/s.

Ski-geometric parameters do not differ between ACL injury mechanisms in recreational alpine skiing

Purpose It is not known so far if ski-equipment-related factors differ between the ACL injury mechanisms, potentially influencing the circumstances and causes of falling, finally resulting in ACL injury. More specifically focusing on the injury mechanisms will provide a deeper understanding of injury causation. The aim of the study was to evaluate whether ACL injury mechanisms in recreational alpine skiing differ with regard to ski-geometric parameters, self-reported circumstances and causes of accident and injury severity. Methods Among a cohort of 392 ACL-injured (57.9% females) skiers, age, sex, height, weight, skill level, risk-taking behavior, circumstances and causes of accident, and ACL injury severity were collected by questionnaire. Additionally, patients had to recall their type of fall (ACL injury mechanism) by classifying forward and backward falls with and without body rotation. Ski length, side cut radius and widths of the tip, waist and tail were directly notated from the ski. Results The forward fall with body rotation was the most common reported ACL injury mechanism (63%). A riskier behavior was associated with forward falls without body rotation. Ski-geometric parameters did not significantly influence the type of ACL injury mechanism. Regarding accident characteristics, catching an edge of the ski was more frequent (p < 0.001) the cause for forward falls (75% and 67%) when compared to the backward falls (46 and 15%) and executing a turn was the most frequent action in all falls (39–68%). A complete rupture of the ACL (66–70%) was more commonly reported than a partial tear (30–34%) among all four non-contact ACL injury mechanisms (n.s.). Conclusion In contrast to risk-taking behavior and accident characteristics, ski-geometric parameters and injury severity do not significantly differ between ACL injury mechanisms in recreational skiing. Thus, an individual skiing style seems to have more impact on ACL injury mechanisms than ski equipment. Future studies should evaluate potential effects of ski geometry on the incidence of ACL injury. Level of evidence III.

SOME PROBLEMS ABOUT THE MOTION OF A RIGID BODY IN A RESISTIVE MEDIUM

The dynamics of rotating rigid bodies is a classical topic of study in mechanics. In the eighteenth and nineteenth centuries, several aspects of a rotating rigid body motion were studied by famous mathematicians as Euler, Jacobi, Poinsot, Lagrange, and Kovalevskya. However, the study of the dynamics of rotating bodies of still important for aplications such as the dynamics of satellite-gyrostat, spacecraft, re-entry vehicles, theory of gyroscopes, modern technology, navigation, space engineering and many other areas. A number of studies are devoted to the dynamics of a rigid body in a resistive medium. The presence of the velocity of proper rotation of the rigid body leads to the apearance of dissipative torques causing the braking of the body rotation. These torques depend on the properties of resistant medium in which the rigid body motions occur, on the body shape, on the properties of the surface of the rigid body and the distribution of mass in the body and on the characters of the rigid body motion. Therefore, the dependence of the resistant torque on the orientation of the rigid body and its angular velocity can de quite complicated and requires consideration of the motion of the medium around the body in the general case. We confine ourselves in this paper to some simple relations that can qualitative describe the resistance to rigid body rotation at small angular velocities and are used in the literature. In setting up the equations of motion of a rigid body moving in viscous medium, we need to consider the nature of the resisting force generated by the motion of the rigid body. The evolution of rotations of a rigid body influenced by dissipative disturbing torques were studied in many papers and books. The problems of motion of a rigid body about fixed point in a resistive medium described by nonlinear dynamic Euler equations. An analytical solution of the problem when the torques of external resistance forces are proportional to the corresponding projections of the angular velocity of the rigid body is obtain in several works. The dependence of the dissipative torque of the resistant forces on the angular velocity vector of rotation of the rigid body is assumed to be linear. We consider dynamics of a rigid body with arbitrary moments of inertia subjected to external torques include small dissipative torques.

Development of an innovative technology for accelerated cooking of no yeast bread using ion-ozonized water

Natural baking starter made from common ingredients such as flour, water and sugar is considered healthy. Any starter obtained by spontaneous fermentation is always a symbiosis of lactic acid bacteria and yeast. Lactic acid bacteria and yeast get along well together and in the course of their life enrich bread with the most valuable compounds, including short-chain organic acids, dietary fiber, essential amino acids, vitamins, etc. On the basis of the obtained research results, a recipe and technological modes for preparing dough for no yeast bakery products from wheat flour of the first grade with the use of ion-ozonized water, whey and natural starter have been developed. The dough was prepared in a safe way under pressure in a kneading-beating ion-ozone cavitation unit. The recipe components (raw materials) of the dough were loaded into the kneading body of the unit, then the dough was replaced for 5 minutes at a kneading body rotation frequency of 5 s-1 in different rotation modes and times. Then the ion-ozone treatment was carried out using an excess pressure of 0.40 MPa (cavitation) and the dough was knocked down. The nutritional value, safety and shelf life of the developed no yeast bakery products with the addition of whey, starter and ion-ozonized water have been determined. It was found that in terms of organoleptic and physicochemical indicators, bread samples prepared from first grade wheat flour and ion-ozonized water without yeast and using whey are almost 2 times inferior to the quality of the control sample. As a result, it was found that churning for 3–5 minutes at a kneading body rotation frequency of 4–5 s-1 will be the optimal mode for obtaining a no yeast dough made from first grade flour on starter with the addition of whey and ion-ozonized water

Mental body rotation with egocentric and object-based transformations in different postures: standing vs. balancing

BACKGROUND: Previous studies suggest better visual-spatial processing when participants are tested in postures in which dynamic stability is challenged. The question arises if this is also true for the performance in mental body-rotation tasks (MBRT). AIM: Taking the embodied cognition approach into account, the first aim of the present study was to examine the potential influence of different demands on dynamic stability for two postures (parallel stand vs. tandem stand) on solving two versions of the MBRT, inducing either an object-based or an egocentric perspective transformation strategy. The second aim was to investigate if these different demands on dynamic stability are reflected in postural sway parameters. METHOD: Thirty participants (18 females and 12 males) were tested in the two MBRTs and in a control condition. All tasks were performed while standing on a balance beam in tandem stand and in a feet parallel position on a force plate. RESULTS: The results for response time and response error revealed effects of rotation angle and task, but no effect of posture. The analyzed Center of Pressure (CoP) data revealed a reduction of body sway during the MBRT for egocentric perspective transformations. CONCLUSION: The results indicate that participants performed better for egocentric than for object-based transformations and that the egocentric transformation leads to more postural stability than the object-based.

Wing structure and neural encoding jointly determine sensing strategies in insect flight

Animals rely on sensory feedback to generate accurate, reliable movements. In many flying insects, strain-sensitive neurons on the wings provide rapid feedback that is critical for stable flight control. While the impacts of wing structure on aerodynamic performance have been widely studied, the impacts of wing structure on sensing are largely unexplored. In this paper, we show how the structural properties of the wing and encoding by mechanosensory neurons interact to jointly determine optimal sensing strategies and performance. Specifically, we examine how neural sensors can be placed effectively on a flapping wing to detect body rotation about different axes, using a computational wing model with varying flexural stiffness. A small set of mechanosensors, conveying strain information at key locations with a single action potential per wingbeat, enable accurate detection of body rotation. Optimal sensor locations are concentrated at either the wing base or the wing tip, and they transition sharply as a function of both wing stiffness and neural threshold. Moreover, the sensing strategy and performance is robust to both external disturbances and sensor loss. Typically, only five sensors are needed to achieve near-peak accuracy, with a single sensor often providing accuracy well above chance. Our results show that small-amplitude, dynamic signals can be extracted efficiently with spatially and temporally sparse sensors in the context of flight. The demonstrated interaction of wing structure and neural encoding properties points to the importance of understanding each in the context of their joint evolution.

Contribution of arm movements to recovery after a trip in older adults.

Falls are common in daily life, and our arms play an important role in recovering balance after a trip. Although older adults fall more often with more serious consequence, there is limited research into arm movements during falls in older adults. We investigated how older adults use their arms to recover from a trip and the difference between fallers and non-fallers. Sixteen older participants walked along a walkway and were occasionally tripped using a custom tripping device. A biomechanical model used full-body marker and force-plate data to calculate the body rotation during the trip, and simulated the rotation without arms (Cut) and with transfer of the arms momentum to the body (Transfer & Cut). We only analysed the first trip, distinguishing fallers (n=5) from non-fallers (n=11). Apart from an expected increase in forward body rotation at foot touchdown in fallers, we found no significant differences between fallers and non-fallers in the effects of arm movements on trip recovery. Like earlier studies in young participants, we found that arm movements had most favourable effect in the transversal plane: by delaying the transfer of angular momentum of the arms to the body, participants rotated the tripped leg more forward thereby allowing more room for a larger recovery step. Older adults that are prone to falling might improve their recovery from a trip by learning to [further] prolong ongoing arm movement.