Dual Tasking during Trip Recovery and Obstacle Clearance among Young, Healthy Adults in Human Factors Research

Trip-induced falls are extremely common in ergonomic settings. Such situations can lead to fatal or non-fatal injuries, affecting the workers’ quality of life and earning capacity. Dual tasking (DT) is a leading cause of trips and ineffective obstacle clearance among workers. DT increases their attentional demand, challenging both postural control and concurrent secondary tasks. As the human brain has limited attentional processing capacity, even young, healthy adults need to prioritize duties during DT. This article aimed to analyze these secondary task types and their applications in recent trip-related studies conducted on young, healthy adults. An extensive review of the recent trip-related literature was performed to provide a condensed summary of the dual tasks used. In previous trip-related literature, distinct types of secondary tasks were used. The choice of the concurrent task must be made vigilantly depending on the occupation, environmental context, available resources, and feasibility. DT can be used as a tool to train workers on selective attention, which is a lifesaving skill in ergonomic settings, especially in the occupations of roofers, construction workers, or truck drivers. Such training can result in successful obstacle clearance and trip recovery skills, which eventually minimizes the number of falls at the workplace.

Stay Out of the Blast Radius: Influence of Surgical Masks on Virtual Pedestrian Interactions

To combat the global pandemic caused by COVID-19, a series of mitigation strategies have been proposed by governments around the world. While responses varied across different governing bodies, recommendations such as social distancing and the use of facial masks were nearly universal. Considering that even with restrictions in place, walking in community environments remained an important component of everyday life, these public health recommendations, as well as the anxiety generated by the pandemic, are likely to have influenced pedestrian interactions. In this study, we have examined the effect of facial masks and anxiety related to community ambulation in the context of the COVID-19 pandemic. Using virtual reality, obstacle circumvention strategies in response to approaching pedestrians with and without facial masks were measured in a sample of 11 healthy young individuals. Additionally, a questionnaire was developed and used to gain insights into the participant's behaviours during and after a strict period of restrictions that were in effect before the summer of 2020. Results showed that participants maintained a larger obstacle clearance when virtual pedestrians wore a facial mask. The extent of obstacle clearance was also positively associated with anxiety towards community ambulation in the context of the pandemic. Our findings provide evidence that mask-wearing results in an increase in physical distancing during pedestrian interactions, which may help to reduce the risk of infection. Furthermore, results demonstrate the effects of social context and psychological status on pedestrian interactions and highlight the potential of virtual reality simulations to study locomotion in natural community settings.

Aging Affects Multi-Objective Optimal Control Strategies during Obstacle Crossing

Obstacle crossing challenges balance and increases the risk of falls in older people. Knowledge of the control strategies adopted by older people will be helpful for the study of the mechanisms of falls during obstacle crossing and the development of fall-prevention approaches. A mechanical model of the body combined with measured gait data was used to study the control strategies adopted by 17 healthy older and 17 young adults when crossing obstacles of different heights, in terms of the best-compromise weighting sets for the objectives of minimizing energy expenditure and maximizing the toe-obstacle and heel-obstacle clearances. The older group showed increased leading toe-obstacle clearance and trailing toe-obstacle distance, but decreased leading heel-obstacle distance. Compared with the young, the crossing strategy of older people emphasized the foot-obstacle clearance to reduce the risk of tripping, at the expense of energy expenditure. It appears that the multi-objective optimal control strategy relies on the muscular strength of the lower extremities and precise end-point control. Therefore, maintaining or improving the muscle strength and the ability of limb position control is critical for safe and successful obstacle-crossing in the older population.

Cross-country ability of tracked vehicles

Research aims to determine conditions and parameters under which the tracked vehicle overcomes stone fields and separate blocks (boulders). Research methodology included the methods of analytical mechanics and mathematical analysis. Results. Mining and geological conditions of deposits gradually get more complicated, while mining moves to remote northern regions, which is a characteristic feature of the Holocene epoch. Road, weather, and natural conditions in arctic and northern territories differ markedly from other regions. Ridges, mounds, lake plains, and marshland are the predominant landscape. Stone fields, marshes, permafrost, marshy hollows, and deep ravines impede the traffic. Due to these factors it is particularly difficult to access and explore in arctic and northern territories. There are particular technical specifications for the exploration equipment, namely, increased cross-country ability for weak soil (snow and swamp), ability to overcome stone fields, increased haulage and towing capacity with the account of maximum possible environmental regulatory compliance, etc. The conditions of ascent and overturning are derived from geometry, while the sliding condition is derived from statics. Summary. A mathematical model has been created, which makes it possible to describe the tracked vehicle’s travel across the uneven ground and, under known design values of the vehicle, determine the limitary obstacle clearance.

Computational Design of Compositionally Graded Alloys for Property Monotonicity

Compositionally graded alloys can realize multiple conflicting properties in the same part, but the formation of secondary phases can often lead to cracks or deleterious properties. In prior work, a computational methodology was presented that can design compositional gradients to avoid these phases at any temperature in high dimensions [1]. The methodology also optimizes paths for a specified cost function, but prior work only considered minimizing path length or maximizing obstacle clearance. In this work, a new cost function is presented to produce compositional paths with optimal property gradients. Specifically, monotonicity is presented as the optimal quality of a pathwise property gradient because monotonic property gradients can be transformed to nearly any form on the part by controlling deposition rate. The proposed cost function uses a metric for non-monotonicity to find the shortest path with monotonic properties and is shown to be compatible with optimal path planners. A synthetic case study examines the effect of a cost function parameter on the trade-off between length and monotonicity. The cost function is also demonstrated in the Fe-Co-Cr system to find a compositional path with monotonic gradients in Coefficient of Thermal Expansion (CTE). The deposition of the path on a hypothetical part is then planned subject to a maximum deposition rate and CTE gradient. Future work is proposed to extend the framework to optimize multiple properties at once and to incorporate Multi-Material Topology Optimization (MMTO) techniques into a complete design methodology for functionally graded metal parts.

Displacement of Slow-Turnover DNA Glycosylases by Molecular Traffic on DNA

In the base excision repair pathway, the initiating enzymes, DNA glycosylases, remove damaged bases and form long-living complexes with the abasic DNA product, but can be displaced by AP endonucleases. However, many nuclear proteins can move along DNA, either actively (such as DNA or RNA polymerases) or by passive one-dimensional diffusion. In most cases, it is not clear whether this movement is disturbed by other bound proteins or how collisions with moving proteins affect the bound proteins, including DNA glycosylases. We have used a two-substrate system to study the displacement of human OGG1 and NEIL1 DNA glycosylases by DNA polymerases in both elongation and diffusion mode and by D4, a passively diffusing subunit of a viral DNA polymerase. The OGG1–DNA product complex was disrupted by DNA polymerase β (POLβ) in both elongation and diffusion mode, Klenow fragment (KF) in the elongation mode and by D4. NEIL1, which has a shorter half-life on DNA, was displaced more efficiently. Hence, both possibly specific interactions with POLβ and nonspecific collisions (KF, D4) can displace DNA glycosylases from DNA. The protein movement along DNA was blocked by very tightly bound Cas9 RNA-targeted nuclease, providing an upper limit on the efficiency of obstacle clearance.

A comparison of two-dimensional and three-dimensional techniques for determining the kinematic patterns for hindlimb obstacle clearance during sheep locomotion.

Background: Analysis of locomotion is often used as a measure for impairment and recovery following experimental peripheral nerve injury. Compared to rodents, sheep offer several attractive features as an experimental model for studying peripheral nerve regeneration. There are no studies on locomotion outcomes after peripheral nerve injury and repair in the sheep model. In the present study, we performed and compared two-dimensional (2D) and, for the first time, three-dimensional (3D) hindlimb kinematics during obstacle avoidance in the ovine model. This study aimed to obtain kinematic data to serve as a template for an objective assessment of the ankle joint motion in future studies of common peroneal nerve (CP) injury and repair in the ovine model. Results: The strategy used by the sheep to bring the hindlimb over a moderately high obstacle, set to 10% of its hindlimb length, was the pronounced knee, ankle and metatarsophalangeal flexion when approaching and clearing the obstacle. Despite the overall time course kinematic patterns about the hip, knee, ankle, and metatarsophalangeal were identical, we found significant differences between values of the 2D and 3D joint angular motion. Conclusions: Our results show that the most apparent changes that occurred during the gait cycle were for the ankle and metatarsophalangeal joints, whereas the hip and knee joints were much less affected. Data and techniques described here are likely to be useful for an objective assessment of altered gait after CP injury and repair in an ovine model.