Wheeled assistive device for load carriage – the effects on human gait and biomechanics

Abstract

Soldiers are often required to carry loads which impose biomechanical strain on the human body. This can adversely affect physical performances. Recently, wheel-based devices (WBD) were designed to reduce the load on the soldier. In the present study, a prototype of this newly developed WBD was evaluated. Thirteen volunteers performed three exercise protocols on a treadmill as follows: (1) no load; (2) carrying 40% of their bodyweight with a backpack or; (3) with the WBD. Data acquisition included: gait parameters, vertical ground reaction forces (VGRF) and contact pressure acting on the shoulder. Biomechanical analysis showed that the WBD decreased the contact pressure on the shoulder and the VGRF. However, greater gait variability, in terms of cycle-to-cycle gait line generation, was observed, which might point to a difficulty in maintaining stability while walking. The study suggests that WBD has a potential to reduce the biomechanical strain on the soldier while carrying heavy loads. Future potential adjustments for the development of a better WBD-based solution are suggested.

Practitioner Summary: The present research observed the potential biomechanical advantages of using a wheel-based device designed to reduce the load on the soldier. It contributed to a lower mechanical force on the soldier’s body, yet causing modulations in gait control. Future design adjustments should be made to optimise the platform.     

Does social capital affect SNS usage? A look at the roles of subjective well-being and social identity

This study views social capital as a precursor of SNS (Social Network Service) use, which departs from the previous thoughts that considered social capital as the outcome of SNS activities. Drawing upon the theoretical premises regarding network-based social capital, this study examines the roles of subjective well-being and social identity in terms of their moderating as well as mediating influences on SNS use. This study sought to sub-categorize social capital and SNS use with a view to providing more refined theoretical and practical implications. The study’s main objectives are three-fold: First, the study verifies whether social capital, categorized into bridging and bonding capital, influences one’s SNS use as measured by qualitative use and quantitative use. Second, the study aims to confirm whether subjective well-being mediates between social capital and SNS use. Third, it examines whether social identity moderates the relationship between social capital and SNS use.The study result indicates that bridging capital only had a significant impact on qualitative use. However, subjective well-being did not mediate the relationship between social capital and SNS use. Finally, the cognitive identity caused significant difference in the effect of social capital on quantitative SNS use, whereas cognitive and affective identities caused significant differences in regards to the effects of bridging capital on qualitative SNS use.     

Does color of warnings affect risk perception?

Colors are used with signal words in warning messages to attract attention of users and to communicate the hazards associated with a product. The signaling property of color has only recently been examined. Standards that associate colors with levels of hazards have not been based on empirical study. Four experiments reported here obtained responses relating relative risks to colors. In one experiment color of background produced a significant difference, but succeeding results suggested this was related to lack of salience of the signal words in that format. In general, the combinations of colors with signal words suggested by various standards organizations were not found to fit the population stereotype. The dominant response of red is associated with risks at all levels. The results are discussed in terms of strategies for warnings. A conclusion is that shape or other graphical configurations may serve better than color to convey level of risk.

Relevance to industry

Many hazardous circumstances in industry must be warned against. The form of warnings is important to gain attention. Color associated with warnings has been assumed to influence risk perception. These results suggest that without training the combinations used are not recognized. Only red is considered relevant.     

Metabolic and cardiopulmonary responses of older wheelchair-dependent and ambulatory patients during locomotion∗

To determine preferred velocities and magnitudes of metabolic and cardiopulmonary responses of older wheelchair-dependent (WD) patients and ambulatory (AMB) psychiatric patients during locomotion, eight WD (mean age 62 years) and ten AMB (mean age 58 years) patients travelled over a level tiled circular course. During wheelchair locomotion and walking, respectively, mean results were: velocity, 2·0, 3·1 km hour^?1; oxygen uptake, 0·532, 0·8061min^?1; net locomotive energy cost, 0·574, 0·558netkcal kg^?1 km^?1; pulmonary ventilation, 19·6, 25·71 min^?1; heart rate, 94·6, 92·7 beats min^?1. Although walking at 3·1 km hour^?1 required greater absolute energy expenditure than for wheelchair locomotion at 2·0 km hour^?1, locomotive efficiency was approximately the same. When considering differences in exercise capability between arms and legs, relative stresses experienced by the WD and AMB subjects appeared to be similar. Locomotive efficiency was reduced when the AMB subjects reduced their walking speed to 20km hour^?1. This study suggests that self-selected velocities for wheelchair locomotion and walking are related to both maximal physical capability for each activity and locomotive efficiency.     

Investigation of the relationship between Ironworker’s gait stability and different types of load carrying using wearable sensors

Load carrying can cause changes in gait stability. Maintaining gait stability (body balance) on a steel frame is an important factor in the prevention of accidents. However, the effects of load carrying on a restricted surface (width), where ironworkers usually perform their jobs, have rarely been investigated. In this context, this study investigates the effect of different types of load-carrying scenarios on the gait stability of ironworkers. Accordingly, to identify the relationships between the weight of load, type of load-carrying method, type of load-carrying tools, and gait stability, represented as the dynamic time warping (DTW) values, an experiment was conducted under 15 different load-carrying conditions. The change in DTW according to the different load conditions was as follows: For one-handed load-carrying using a toolbox, the average DTW values were 23.31 at a weight of 3 kg, 23.80 at 6 kg, 33.20 at 10 kg, 65.84 at 16 kg, and 103.50 at 20 kg. Moreover, for one-handed load-carrying using a bucket, the average DTW values were 23.07 at 3 kg, 24.76 at 6 kg, 34.35 at 10 kg, 77.52 at 16 kg, and 108.28 at 20 kg. Finally, in the case of both-handed load carrying, the average DTW values were 24.31 at 6 kg, 28.11 at 10 kg, 27.23 at 16 kg, 37.90 at 20 kg, and 40.96 at 32 kg. As the weight of the load increased, the DTW values in almost all the experimental cases also increased. Furthermore, the DTW values for bucket carrying and tool box carrying showed clear differences above a certain weight (16 kg). Thus, the results of the experiments indicate that different types of load-carrying conditions significantly affect the ironworkers’ gait stability as they walk on a steel frame. Finally, the calculated DTW values were compared with the subjective perceived ratings to validate the experimental results. The DTW value was highly correlated with the subjective perceived rating scores (Pearson coefficient: 0.929). The results of this study will facilitate the use of gait stability measurements to enhance the construction safety of ironworkers.     

Spine loading during laboratory-simulated fireground operations — inter-individual variation and method of load quantification

Abstract

Spine loading data are needed to design low-back health-preserving ergonomic interventions for firefighters. Study objectives were to quantify spine loads during simulated fireground operations using simple (polynomial) and advanced (EMG-assisted musculoskeletal model) methods and to describe the variation in spine loads between performers (N?=?20). Spine compression forces differed by as much as 5.5 times bodyweight between individuals performing identical tasks. Anteroposterior and mediolateral shear forces varied by as much 3.2 and 2.1 times bodyweight between individuals performing the same tasks, respectively. Large variations in spine load magnitudes were documented regardless of whether simple or advanced quantification methods were used. Results suggest that low-back loading demands on the fireground would vary widely depending on the physical characteristics of individual firefighters, movement strategies employed, and tasks performed. Thus, personalised ergonomic interventions are warranted to regulate spine loading and load tolerance in firefighters.

Practitioner summary: Even when performing the same work, the associated spine loading demands will vary widely across people due to differences in their body sizes, shapes, and movement strategies. Therefore, personalised interventions are needed to regulate spine loading and load tolerance in workers (e.g. obesity prevention, physical capacity-building exercise, and movement [re]training).     

Does prolonged sitting with limited legroom affect the flexibility of a healthy subject and their perception of discomfort?

This study examined for differences in subjective ratings of discomfort and comfort (Numerical Rating Scale) and objective measures of hamstring (Sit-Reach test), lumbar (Schöber’s test) and neck (Cervical Range of Motion) flexibility in healthy young subjects (n = 24) following 4 h of sitting on stacking chairs with or without limited legroom.When comparing the limited and unlimited legroom groups for differences in subjective and objective measures over 4 h, no significant findings were seen at the 5% level of confidence. However, differences in buttock, neck, shoulder and average discomfort were significantly negatively correlated to differences between post-warm up Sit-Reach scores (Correlation Co-efficients: −.763, −.434, −.408, and −.445; p values of .004, .034, .048, and .029, respectively). The difference in buttock discomfort was significantly negatively correlated to the difference between pre-warm up Sit-Reach scores (Correlation Coefficient: −.750; p = 0.005), post-sitting/pre-warm up and pre-sitting/post-warm up Sit-Reach scores (Correlation Coefficient: −.756; p = 0.004), and Schöber’s tests (Correlation Coefficient: −.578; p = 0.049).Although the above results suggest a relationship between a loss in flexibility and an increase in discomfort, the mechanism influencing this relationship is not clear from this study. What does appear clear is that the limiting of legroom to the parameters used in this study does not seem to exacerbate change in flexibility and discomfort which are a consequence of prolonged sitting.

Relevance to industry

Many forms of public transport provide limited legroom for their passengers, which may have an adverse affect on the user’s flexibility or experience of discomfort. Determining which objectively measurable parameters are associated with the subjective level of discomfort during sitting should allow for a greater appreciation of the changes that underpin such subjective perceptions.     

Does display configuration affect information sampling performance?

This investigation sought to determine the influence of a visual display's spatial configuration on participant's ability to sample linguistic information. Line drawings circumscribed 36 areas shaped like squares, rectangles, ‘T’, ‘L’, and ‘+’, among others. Each such ‘shape’ was presented for 1000 ms, followed by a 12-letter matrix presented for 50 ms. Participants then reported the letters that would have been inside the boundary contour if it were superimposed on the letter matrix. The results indicated that single, spatially contiguous areas could be monitored better than separate areas; the recall of simple configurations seemed better than that of more complex ones, while outlying positions tended to be ignored. The data were thus viewed as compatible with recent theories of perceptual organization in displays, such as the notion of ‘common region’ and the proximity compatibility principle. Informational complexity (IC) proved somewhat better than figural compactness (FC) in accounting for the data in terms of information theory. The findings may help to specify the optimal spatial configurations for visually displayed linguistic information in a variety of contexts, including head-up displays (HUDs).     

Does ethical ideology affect software piracy attitude and behaviour? An empirical investigation of computer users in China

This study empirically examines Chinese computer users’ ethical ideology and its relationship to their software piracy attitude and behaviour. The investigation reveals several important findings. First, cluster analysis results show that Chinese computer users can be divided into four ethical ideology types (i.e., situationists, absolutists, subjectivists, and exceptionists) reasonably consistent with Forsyth's taxonomy. Second, when compared with situationists, absolutists, and exceptionists, subjectivists are found to have the least unfavourable attitude towards software piracy and are most frequently engaged in software piracy. Third, Chinese computer users’ ideological relativism exerts a stronger influence on their software piracy attitude and behaviour than does their ideological idealism. The findings suggest that the government, and authentic software developers and vendors should focus on subjectivists as their target audience of anti-software piracy communications. These policy makers and practitioners should also make concerted efforts to help subjectivists better realise how their software piracy act may damage parties ‘proximate’ to themselves so as to lower the rate of software piracy.     

Does non‐destructive earthquake experience affect risk perception and motivate preparedness?

There are thousands of earthquakes every year, but most of them are small and are not disasters. This study explored whether non‐destructive earthquake experience affects public risk perception and motivates preparedness. The study respondents were from the Jiaodong Peninsula, China, where more than 20 small earthquakes have occurred during the past decade. The results show that non‐destructive earthquake experience positively affected public perception of the probability of an earthquake but not the perception of consequences. The relationship between non‐destructive earthquake experience and preparedness intention was not statistically significant. In addition, this study revealed that the perception of consequences was a positive predictor of earthquake preparedness intention, that is people with higher levels of perceived consequences of an earthquake were more likely to be motivated to prepare. However, non‐destructive earthquake experience moderated this relationship, that is weakened the strength of this relationship between perceived consequences and skill preparedness intention. These findings permit the identification of potential pathways to increase levels of disaster preparedness and potential barriers to enhancing disaster resilience in regions experiencing small hazards.     

Optimal position and rating of DG in distribution networks by ABC–CS from load flow solutions illustrated by fuzzy-PSO

In this work, load flow problems of both radial distribution networks (RDNs) and mesh distribution networks (MDNs) have been solved using hybrid fuzzy-PSO algorithm. A new voltage stability index (VSI) is also indicated. Based on the suggested load flow, distributed generation (DG) is ready to conduct through the requirement; and with the support of inserting the optimal-sized DG unit in an exact way, the distribution system’s stability is also studied. The exact position of each DG unit has been computed using “loss sensitivity analysis,” whereas the optimal sizing of each DG unit has been done with the help of hybrid artificial bee colony and Cuckoo search algorithm. The suggested method is tested in the regular 33-node and 69-node RDNs as well as in 85-node and 119-node MDNs. The transcendence of the proposed operation has been centered with the aid of comparison to the other existing methods. The suggested VSI is also correlated with other two existing VSIs before and after placement of DG unit(s).

     

Do subjective symptoms predict our perception of jet-lag?

A total of 39 subjects were studied after a flight from the UK to either Sydney or Brisbane (10 time-zones to the east). Subjects varied widely in their age, their athletic ability, whether or not they were taking melatonin, and in their objectives when in Australia. For the first 6 days after arrival, subjects scored their jet-lag five times per day and other subjective variables up to five times per day, using visual analogue scales. For jet-lag, the scale was labelled 0 = no jet-lag to 10 = very bad jet-lag; the extremes of the other scales were labelled - 5 and + 5, indicating marked changes compared with normal, and the centrepoint was labelled 0 indicating 'normal'. Mean daily values for jet-lag and fatigue were initially high (+ 3.65 +/- 0.35 and + 1.55 +/- 0.22 on day 1, respectively) and fell progressively on subsequent days, but were still raised significantly (p < 0.05) on day 5 (fatigue) or day 6 (jet-lag). In addition, times of waking were earlier on all days. By contrast, falls in concentration and motivation, and rises in irritability and nocturnal wakings, had recovered by day 4 or earlier, and bowel activity was less frequent, with harder stools, on days 1 and 2 only. Also, on day 1, there was a decrease in the ease of getting to sleep (- 1.33 +/- 0.55), but this changed to an increase from day 2 onwards (for example, + 0.75 +/- 0.25 on day 6). Stepwise regression analysis was used to investigate predictors of jet-lag. The severity of jet-lag at all the times that were measured was strongly predicted by fatigue ratings made at the same time. Its severity at 08:00 h was predicted by an earlier time of waking, by feeling less alert 30 min after waking and, marginally, by the number of waking episodes. Jet-lag at 12:00 and 16:00 h was strongly predicted by a fall of concentration at these times; jet-lag at mealtimes (12:00, 16:00 and 20:00 h) was predicted by the amount of feeling bloated. Such results complicate an exact interpretation that can be placed on an assessment of a global term such as jet-lag, particularly if the assessment is made only once per day.     

Does privacy breach affect firm performance? An analysis incorporating event-induced changes and event clustering

Previous studies have analyzed the impact of cybersecurity breaches on firm performance, but the impact of the privacy breach on firm performance is less explored. Needless to say, the privacy of the individual's personal information has been a rising concern for organizations over the years. Previous studies, primarily focused on cybersecurity breaches, have used a simple market model (MM) to observe the impact of these breaches on firm performance. Our study has used an advanced market model (AMM), which observes the event-induced changes in the variance of stock returns and changes in MM parameters, which are ignored by the MM. The ignorance of this may lead to a biased cumulative abnormal return (CAR) computation. We have also included the event clustering observation (events that are very close to each other) in our study and evaluated AMM with seemingly unrelated regression (SUR), i.e., AMM-SUR. We have used data of 193 privacy breaches related to the US firms listed on NYSE (USA), NASDAQ (USA) for the years 2012 (43 breaches), 2013 (37 breaches), 2014 (51 breaches), and 2018 (62 breaches). Abnormal returns for the firms are found negative due to these privacy breaches, but AMM consistently reports more negative abnormal returns than MM for all the years. The AMM-SUR, observing event clustering, consistently reports slightly lower negative abnormal returns than the AMM for all the years. We have also calculated the average financial loss due to a privacy breach for these years and for three different models, i.e., MM, AMM, and AMM-SUR.     

Do subjective symptoms predict our perception of jet-lag?

A total of 39 subjects were studied after a flight from the UK to either Sydney or Brisbane (10 time-zones to the east). Subjects varied widely in their age, their athletic ability, whether or not they were taking melatonin, and in their objectives when in Australia. For the first 6 days after arrival, subjects scored their jet-lag five times per day and other subjective variables up to five times per day, using visual analogue scales. For jet-lag, the scale was labelled 0= no jet-lag to 10= very bad jet-lag; the extremes of the other scales were labelled ?5 and +5, indicating marked changes compared with normal, and the centrepoint was labelled 0 indicating ‘normal’. Mean daily values for jet-lag and fatigue were initially high (+ 3.65 ± 0.35 and + 1.55 ± 0.22 on day 1, respectively) and fell progressively on subsequent days, but were still raised significantly (p < 0.05) on day 5 (fatigue) or day 6 (jet-lag). In addition, times of waking were earlier on all days. By contrast, falls in concentration and motivation, and rises in irritability and nocturnal wakings, had recovered by day 4 or earlier, and bowel activity was less frequent, with harder stools, on days 1 and 2 only. Also, on day 1, there was a decrease in the ease of getting to sleep (? 1.33 ± 0.55), but this changed to an increase from day 2 onwards (for example, + 0.75 ± 0.25 on day 6). Stepwise regression analysis was used to investigate predictors of jet-lag. The severity of jet-lag at all the times that were measured was strongly predicted by fatigue ratings made at the same time. Its severity at 08:00 h was predicted by an earlier time of waking, by feeling less alert 30 min after waking and, marginally, by the number of waking episodes. Jet-lag at 12:00 and 16:00 h was strongly predicted by a fall of concentration at these times; jet-lag at mealtimes (12:00, 16:00 and 20:00 h) was predicted by the amount of feeling bloated. Such results complicate an exact interpretation that can be placed on an assessment of a global term such as jet-lag, particularly if the assessment is made only once per day.     

Comments on the “Influence of the load modelling during gait on the stress distribution in a femoral implant” by Gervais et al.

Multibody System Dynamics -     

Does the level of detail of UML diagrams affect the maintainability of source code?: a family of experiments

Although the UML is considered to be the de facto standard notation with which to model software, there is still resistance to model-based development. UML modeling is perceived to be expensive and not necessarily cost-effective. It is therefore important to collect empirical evidence concerning the conditions under which the use of UML makes a practical difference. The focus of this paper is to investigate whether and how the Level of Detail (LoD) of UML diagrams impacts on the performance of maintenance tasks in a model-centric approach. A family of experiments consisting of one controlled experiment and three replications has therefore been carried out with 81 students with different abilities and levels of experience from 3 countries (The Netherlands, Spain, and Italy). The analysis of the results of the experiments indicates that there is no strong statistical evidence as to the influence of different LoDs. The analysis suggests a slight tendency toward better results when using low LoD UML diagrams, especially if used for the modification of the source code, while a high LoD would appear to be helpful in understanding the system. The participants in our study also favored low LoD diagrams because they were perceived as easier to read. Although the participants expressed a preference for low LoD diagrams, no statistically significant conclusions can be drawn from the set of experiments. One important finding attained from this family of experiments was that the participants minimized or avoided the use of UML diagrams, regardless of their LoD. This effect was probably the result of using small software systems from well-known domains as experimental materials.     

Does power posing affect gerontechnology adoption among older adults?

Recognising the rise of an aging population and independent living among older adults, many governments and organisations have developed and promoted new technologies in the form of gerontechnologies to support the needs and enhance the well-being of older adults. However, the adoption of products using such technology remains modest among the aging population. This study introduces the notion of power in the form of power posing and examines its impact on new technology adoption, particularly gerontechnology, among older adults. Using an experimental approach on a sample of older adults exposed to an in-house near-field communication-enabled light system, the study finds that high-power poses have a greater and more positive impact on older adults’ perceived ease of use of, perceived usefulness of, and intentions to use gerontechnology than low-power poses. Implications, limitations, and future research directions are discussed.     

Does cognitive load moderate the seductive details effect? A multimedia study

Several studies have shown that adding seductive details to instructional materials has a detrimental effect on learning. However, other studies have shown non-significant findings. The present study uses cognitive load theory as a theoretical framework to explain these controversial results in seductive details research. Using a 2 × 2 experimental design we asked a group of high-school students (N = 100) to learn about biology with a multimedia environment that manipulated the presence of seductive details (with vs. without) and the modality of the verbal information (high load, on-screen text vs. low load, narration). The findings showed that students’ learning performance was significantly higher when seductive details were presented under the low load condition (narration) as compared to all other conditions. The theoretical implications for understanding the effects of non-redundant and interesting, but irrelevant learning material are discussed and future research directions are presented.     

Quality of experience of 360 video – subjective and eye-tracking assessment of encoding and freezing distortions

Multimedia Tools and Applications - The research domain on the Quality of Experience (QoE) of 2D video streaming has been well established. However, a new video format is emerging and gaining...     

Does stock repurchase declaration affect stock price? Differences between the electrics industry and other industries

This study is to discuss the impact of stock repurchase declaration and purpose of repurchase on the stock price in the backdrop of listed companies on Taiwan’s stock market. Event Study Method is employed to discuss stock price fluctuations while GARCH (Generalized Autoregressive Conditional Heteroscedasticity) is applied to estimate the Market Model regressive coefficients. The samples consisted of companies declaring first stock repurchase are selected from August 9, 2000 to December 31, 2005 with a precondition that all the companies shall be listed ones 150 days prior to declaration. The study results reveal that companies from other industries have considerably bigger average CAR than companies of the electrics industry before and after the declaration of stock repurchase. Companies with application purpose of “maintain stockholders’ equities and corporate credit” have considerably bigger average CAR than companies with application purpose of “transferring stocks to employees”. In industries other than electrics, companies with application purpose of “maintain stockholders’ equities and corporate credit” have bigger accumulated abnormal return response than companies with application purpose of “transferring stocks to employees”. In case of “maintain stockholders’ equities and corporate credit” as the application purpose of stock repurchase, companies from industries other than electrics have relatively higher average CAR response. The empirical study results can serve as a reference for the listed company management and to related academic studies.