Ergonomic design and evaluation of a novel laptop desk for wheelchair users.

BACKGROUND: Nowadays, although using laptops to perform many routine activities is inevitable, many wheelchair users are not able to efficiently use their laptops due to their movement limitations and inappropriate workstations. OBJECTIVE: The purpose of this study was to design and evaluate a novel ergonomic laptop desk for wheelchair users by considering their movement limitations. METHODS: In this experimental study, we ergonomically designed and assessed a novel laptop desk in two phases in a laboratory. In the first phase of the study, design specifications were identified by an expert panel; accordingly, a new laptop desk was designed and prototyped for the wheelchair users. In the second phase, in order to evaluate the laptop desk, 14 wheelchair users were asked to complete a typing task within 20 minutes, both with and without using the laptop desk. Postural risk level, perceived discomfort, and task performance were evaluated using the Rapid Upper Limb Assessment (RULA) technique, Local Perceived Discomfort (LPD) questionnaire, and the number of letters typed and typing errors, respectively. RESULTS: The postures of the wrist, arm, and neck regions were corrected from RULA action level 3 to 2 when the designed laptop desk was used. In addition, the average perceived discomfort of the participants significantly decreased in the neck, shoulder, and wrist regions. Furthermore, typing accuracy was improved significantly when novel laptop desk was used. CONCLUSIONS: Accommodating wheelchair user's workstation with the novel designed laptop desk could reduce musculoskeletal disorders risk factors and help wheelchair users to perform their work more efficiently.

Design, Fabrication, and Testing of a Novel Surgical Handwashing Machine.

Background. Surgical hand scrub is strongly recommended as an essential measure to reduce surgical site infections (SSIs). SSI results in morbidity and additional cost. Micropunctures may occur on surgical gloves during operation, thus hand scrub cannot be omitted in any condition. Generally speaking, the adequacy of hand scrub is decided by the surgeon. Only occasionally, surveillance of hygienic status of hands is performed after scrub. Therefore, the potential exists that suboptimal handwash leads to SSIs. There are standards for preoperative handwash, but all of them are operator dependent, and continuous surveillance is actually impossible. One solution is to omit the role of surgeon in handwashing. This can be achieved by designing a standard procedure, performed mechanically by a machine, considering the detailed requirements of hygienic surgical hand scrub. The goal of this study was to develop a procedure that works on the design, fabrication, and trial of a new handwashing machine, for surgical hand scrub. Methods. A machine with a reciprocal spraying mechanism was designed that covers from the fingertips up to the elbow. Various combinations of staged irrigations with antiseptic solutions and water were to be programmed and implemented. Clinical experiments were performed several times with different handwashing programs, and swabs were taken from the skin surface and creases. Results. There was no microbial growth after 72 hours with any handwashing program. Conclusion. The preliminary experiments with this new handwashing machine show promising results for its application in surgical hand scrub.

The Effect of the combination of active vestibular interventions and occupational therapy on Balance in Children with Bilateral Spastic Cerebral Palsy: A pilot randomized Controlled trial.

OBJECTIVE: The current study aimed to examine the effect of the combined administration of active vestibular interventions and occupational therapy on balance and the relationship between balance changes and Activity of Daily Living in school-aged children with cerebral palsy (CP). MATERIALS & METHODS: Twenty-four children with Spastic CP, at the level I and II (according to the "Gross Motor Function Classification System) aged 7-12 years were enrolled and randomly assigned into control and intervention groups. Pediatric Balance Scales and Bruininks-Oseretsky Test of Motor Proficiency II were employed to assess the functional balance changes as well as Force Plate (eyes closed and open) to assess changes in the parameters of balance (e.g. center of pressure excursion). The activity of Daily Living was assessed by "Activity Scales for Kids (performance version)". Participants in the intervention group received active vestibular intervention for 20 min and a regular occupational therapy program for 25 min. The control group received a regular occupational therapy program for 45 min. Interventions were provided 3 d/week for 6 weeks in each group. The participants were assessed in three stages: baseline, immediately after, and eight weeks after the intervention. Data were analyzed by ANOVA and linear regression. RESULTS: The results demonstrated that only functional balance, according to Pediatric Balance Scales scores, was significantly increased in the active vestibular interventions group (p=0.02). There was no significant association between functional balance and Activity of Daily Living (P>0.05). CONCLUSION: The combined administration of active vestibular interventions and occupational therapy could improve the functional balance in children with spastic CP. It may be related to the reorganization of the vestibular system with a controlled and precise application of stimuli.

Effect of viscoelastic properties on passive torque variations at different velocities of the knee joint extension and flexion movements.

This study aimed to investigate the rate of passive torque variations of human knee joint in the different velocities of knee flexion and extension movements. Ten healthy men were invited to participate in the tests. All passive torque tests were performed for the knee joint extension and flexion on the sagittal plane in three different angular velocities of 15, 45, and 120°/s; in 5 consecutive cycles; and within 0° to 100° range of motion. The electrical activity of knee joint extensor and flexor muscles was recorded until there was no muscle activity signal. A Three-element Solid Model (SLS) was used to obtain the viscose and elastic coefficients. As the velocity increases, the stretch rate in velocity-independent tissues increases, and the stretch rate in velocity-dependent tissues decreases. By increasing the velocity, the resistance of velocity-dependent parts increases, and the velocity-independent parts are not affected by velocity. Since the first torque that resists the joint movement is passive torque, the elastic and viscous torques should be simultaneously used. It is better to perform the movement at a low velocity so that less energy is lost. The viscoelastic resistance of tissues diminishes. Graphical abstract.

The effects of task execution variables on resultant vertical ground reaction force acting on foot sole during squat lifting.

The main objective of this study was to investigate the effects of task execution variables on the value and point of application of the resultant vertical ground reaction force acting on the foot sole during squat lifting. This can be of particular importance since it may help to recognize the roles of the foot sole parts in bearing the support force during industrial and labor lifting activities. Twelve healthy men lifted a box with 4, 8 and 12 kg masses at fast and slow speeds. Ground reaction force and center of pressure were measured using two parallel Kistler force-plates. In addition, a Vicon system and a 3D linked segment model were used to define the movement pattern. Significant increases resulted for the peak vertical ground reaction force with the increases in the lift speed (P < 0.05) and box weight (P < 0.05). As well a significant increase resulted for the range of center of pressure location with the increase in the box weight (P < 0.05). Moreover, significant interactions (P < 0.05) between the lift speed and box weight were detected. The front and rear parts of the foot had the most important roles in bearing the support force during the beginning and final phases of movement, respectively. Finally, it was concluded that the value and point of application of vertical ground reaction force are seemingly dependent on the momentum of the subject plus box.

Upper Limb Neuromuscular Activities and Synergies Comparison between Elite and Nonelite Athletics in Badminton Overhead Forehand Smash.

This study is aimed at comparing muscle activations and synergies in badminton forehand overhead smash (BFOS) between elite and nonelite players to clarify how the central nervous system (CNS) controls neuromuscular synergy and activation to generate complex overhead movements. EMG of five upper limb muscles was recorded through surface electromyography (EMG) electrodes from twenty players. Athletics is divided into two groups: elite and nonelite. Eventually, nonnegative matrix factorization (NNMF) was utilized to the calculated electromyography signals for muscle synergy comparison. Similarities between elite and nonelite groups were calculated by scalar product method. Results presented that three muscles synergies could sufficiently delineate the found electromyography signals for elite and nonelite players. Individual muscle patterns were moderately to highly similar between elite and nonelite groups (between-group similarity range: 0.52 to 0.90). In addition, high similarities between groups were found for the shape of synergy activation coefficients (range: 0.85 to 0.89). These results indicate that the synergistic organization of muscle coordination during badminton forehand overhead smash is not profoundly affected by expertise.

Effects of external loading on lumbar extension moment during squat lifting.

OBJECTIVES: The main objective of this study has been qualitative investigation of the effects of external loading on the lumbar extension moment during squat lifting. Findings of this study may allow to determine the factor with the most considerable effect on the lumbar extension moment and may help determine the lumbar spine risk factors at temporo-spatial coordination during squat lifting. MATERIAL AND METHODS: Twelve healthy men volunteered to perform slow and fast squat lifting of a box of varied mass (4 kg, 8 kg and 12 kg). The eight-channel electromyography was applied to detect the activities of abdominal (rectus abdominis and external oblique) and lower back muscles (iliocostalis lumborum and multifidus). The lumbar extension moment was calculated using 3D linked segment model. Ground reaction forces and kinematic data were recorded using a Vicon system with 2 parallel Kistler force-plates. RESULTS: Significant increases (both p-values < 0.05) were detected for the peak lumbar extension moment with increases in the lift speed and box weight. Moreover, a significant interaction (p = 0) was detected between the lift speed and box weight. Furthermore, insignificant differences (all p-values > 0.05) were detected between the lumbar angles related to the lower trunk muscles peak activities and lumbar angle related to the peak lumbar extension moment in most of the lifts. CONCLUSIONS: According to the findings, the inertial force of the lifted box is the most important factor that affects the lumbar extension moment during squat lifting. Moreover, critical lumbar angles are seemingly those ones in which the lifted box reaches the peak acceleration. Int J Occup Med Environ Health 2017;30(4):665-679.

Design and cognitive evaluation of 6 dynamic lane departure warning symbols.

OBJECTIVE: Lane departure, caused by inattention, distraction, drowsiness, or any unusual driver behavior, is a typical risk threatening the driver as well as other road users. Accurate perception of such situations through effective warnings would help drivers to avoid serious consequences. With regard to critical functions of warning symbols for risk communication, the present study focused on providing effective and easily perceivable symbols, compatible with human cognitive capabilities. Thus, the main purpose of the present study was to design and cognitively appraise 6 newly designed dynamic symbols, candidates for a new type of lane departure warning system. METHODS: Simplicity, familiarity, concreteness, meaningfulness, and semantic closeness were the major assessment criteria, defining cognitive features by the earlier researchers in the field. A total number of 187 driving license applicants, with a mean age of 20.58 years (SD = 3.20), participated in the present survey. The participants rated cognitive features of the 6 dynamic symbols along a 0-100 scale. RESULTS: Significant main effect of the element factor type of the designed symbols on rating cognitive features revealed that the existence of car element was the best predictor for illustrating lane departure. The interaction of both element factor and location of element factor significantly affected the ratings. However, the location of element factor did not solely have any strong effect on the ratings. The results also demonstrated that semantic closeness received the highest overall mean score across symbols (M = 61.80), especially within the symbols that include the car element (M = 75.67). Moreover, a significant difference was observed between the average ratings of the cognitive features, despite the fact that a significant correlation was found between cognitive features. CONCLUSION: The most considerable result of the current study was the match between the symbol with the highest ratings and the International Organization for Standardization (ISO)-related icon in appearance. Because previous studies demonstrated a strong correlation between comprehension scores of the symbol and both semantic closeness and meaningfulness, high-level comprehensibility of the best ranked symbol is expected.