Effects of Pacing When Using Material Handling Manipulators

Common manipulator-assisted materials handling tasks were performed in a laboratory simulation at self-selected and faster (paced) speeds. The effects of pacing on peak hand forces, torso kinematics, spine moments and forces, and muscle antagonism were determined, along with any influences of several task variables on these effects. The faster trials were performed 20% more rapidly than the self-paced trials. It was found that (a) achieving this level of performance required 10% higher hand forces and 5%-10% higher torso moments, (b) consistent torso postures and motions were used for both speed conditions, and (c) the faster trials resulted in 10% higher spine forces and 15% higher levels of lumbar muscle antagonism. On whole, these results suggest a higher risk of musculoskeletal injury associated with performance of object transfers at faster than self-selected speeds with and without a manipulator. Further analysis provided evidence that the use of manipulators involves higher levels of motor coordination than do manual tasks. Several implications regarding the use of material handling manipulators in paced operations are discussed. Results from this investigation can be used in the design, evaluation, and selection of material handling manipulators.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67067/2/10.1518_001872099779591240.pd

Fatigue evaluation in maintenance and assembly operations by digital human simulation

Virtual human techniques have been used a lot in industrial design in order to consider human factors and ergonomics as early as possible. The physical status (the physical capacity of virtual human) has been mostly treated as invariable in the current available human simulation tools, while indeed the physical capacity varies along time in an operation and the change of the physical capacity depends on the history of the work as well. Virtual Human Status is proposed in this paper in order to assess the difficulty of manual handling operations, especially from the physical perspective. The decrease of the physical capacity before and after an operation is used as an index to indicate the work difficulty. The reduction of physical strength is simulated in a theoretical approach on the basis of a fatigue model in which fatigue resistances of different muscle groups were regressed from 24 existing maximum endurance time (MET) models. A framework based on digital human modeling technique is established to realize the comparison of physical status. An assembly case in airplane assembly is simulated and analyzed under the framework. The endurance time and the decrease of the joint moment strengths are simulated. The experimental result in simulated operations under laboratory conditions confirms the feasibility of the theoretical approach

Shoulder postural fatigue and discomfort : A preliminary finding of no relationship with isometric strength capability in a light-weight manual assembly task

Does greater strength capacity in the shoulder-complex afford increased protection against regionalized fatigue and discomfort induced by sustained awkward arm postures in light-weight manual assembly environments? This question was addressed by testing the relationship between differences in shoulder complex strength capacity, produced by variations in arm posture within a subject, and among subjects assuming equivalent arm postures, and severity of fatigue and discomfort sensed during a low-exertion manual performance task. Experimental findings showed that: (a) awkward arm postures produced substantial and rapid onset of postural fatigue and discomfort during a light-weight manual performance task where strength demands were low (i.e., less than 15 percent of maximum voluntary contraction (MVC)), (b) variations in strength capability found among arm postures within an individual subject, or 3mong subjects assuming the same arm posture, did not affect onset of substantial fatigue or discomfort when hands are postured near or above shoulder level, and (c) postures which simply appeared to be awkward, or which compromised strength capacity (e.g., working with the arm to the side of the body, or aligned in the coronal plane), did not necessarily increase discomfort of fatigue. Our findings suggest caution against sole reliance upon population or individual worker upper-extremity strength capabilities as predictors of fatigue and discomfort in the shoulder complex when manual exertions are small (e.g., light-weight manual assembly activities involving small parts or small hand-tools) and hands are postured at or above shoulder level.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28697/1/0000517.pd

The effect of a lumbopelvic compression belt on load transfer during the active straight leg test: A proof of concept study using ultrasound imaging

INTRODUCTION: The active straight leg raise (ASLR) test assesses load transfer through the pelvis. During the ASLR, intraabdominal pressure (IAP) rises, increasing the load on the lumbopelvic region. Several studies have shown a correlation between the magnitude of bladder base displacement (BBD) during the ASLR and lumbopelvic instability. Additionally, greater depression of the bladder and pelvic floor muscles is associated with motor control impairments associated with form and force closure. Pelvic stability belts are a common therapeutic intervention for individuals who report pelvic girdle pain. Their mechanism of action is to improve form closure and assist force closure and motor control. Impaired form and force closure mechanisms through the lumbopelvic area are associated poor load transfer, low back pain, sacroiliac pain, stress urinary incontinence and chronic pelvic pain. OBJECTIVES: This study aimed to observe and determine the impact of the ASLR test with and without a Serola lumbopelvic belt on BBD and participant self-reported level of difficulty score. METHODS: A convenience sample of fifteen physical therapy students (mean age 25 years) who were previously identified as having lumbopelvic instability were recruited for this study. PCOM\u27s institutional review board approved the study, and each participant provided informed consent. All participants completed a bladder filling protocol via natural diuresis to standardize bladder volumes to allow for bladder and pelvic floor delineation on ultrasound imaging. A Clarius C3 curvilinear wireless ultrasound unit was used for image acquisition with images displayed on an IPAD. The ultrasound transducer was placed suprapublically on the lower abdomen, oriented transversely, and manipulated until a clear image of the bladder base was apparent. A standard script was read to each participant to standardize testing. The magnitude of BBD was captured with cine loops across two testing conditions: the ASLR test without a lumbopelvic belt which was repeated with the participant wearing a belt. Participants also self-reported the level of difficulty for each testing condition. Participants were fitted with the lumbopelvic belt according to manufacturer’s recommendation. The belt tension was standardized using a manometer set to 20mmHG placed between the belt\u27s anterior aspect and the participant\u27s lower abdomen. On-screen calipers identified the lateral and medial aspects of the bladder base. All images were saved for post hoc analysis to determine the magnitude and direction of BBD between both testing conditions. RESULTS: Descriptive statistics will be reported, and a repeated measures ANOVA will be completed to determine whether there is a statistically significant difference between the means with the level of significance set at p=.05. CONCLUSION: TB

The relationship of isometric strength to peak dynamic hand forces during submaximal weight lifting

Reports have indicated that approximately one third of the US workforce is presently required to exert significant strength as part of their jobs. In addressing the prevention of these types of injuries, the assessment of muscular strength can provide a method of predicting whether a person is capable of performing the job without incurring injury. Currently, isometric strength assessments are often used to assist in predicting the capability to safely perform a lifting task. However, given the dynamic nature of work activities, isometric values may be limited, particularly if the load is well below a person's strength capability. Thus, it is of interest to evaluate the relationship between isometric strength values and peak dynamic hand forces under varied submaximal loading. It is shown in this study that the peak hand forces, exhibited while dynamically lifting different submaximal loads, are not highly correlated with a person's isometric lifting strength in similar postures. It is also shown that for very light load lifting, the peak accelerations approached 2.5 g's, further supporting the need to limit such lifting from floor level by using ergonomic interventions.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30255/1/0000651.pd

Radioisotopes and the Age of the Earth

RATE is an acronym applied to a research project investigating radioisotope dating sponsored by the Institute for Creation Research and the Creation Research Society. It stands for Radioisotopes and the Age of The Earth. This article summarizes the purpose, history, and intermediate findings of the RATE project five years into an eight-year effort. It reports on the latest status of the research on helium diffusion through minerals in granitic rock, accelerated nuclear decay theory, radiohalos, isochron discordance studies, case studies in rock dating, and carbon-14 in deep geologic strata. Each of the RATE scientists will present separate technical papers at the Fifth International Conference on Creationism on the details of this research

Effects of Aging on the Biomechanics of Slips and Falls

Although much has been learned in recent decades about the deterioration of muscular strength, gait adaptations, and sensory degradation among older adults, little is known about how these intrinsic changes affect biomechanical parameters associated with slip-induced fall accidents. In general, the objective of this laboratory study was to investigate the process of initiation, detection, and recovery of inadvertent slips and falls. We examined the initiation of and recovery from foot slips among three age groups utilizing biomechanical parameters, muscle strength, and sensory measurements. Forty-two young, middle-age, and older participants walked around a walking track at a comfortable pace. Slippery floor surfaces were placed on the track over force platforms at random intervals without the participants’ awareness. Results indicated that younger participants slipped as often as the older participants, suggesting that the likelihood of slip initiation is similar across all age groups; however, older individuals’ recovery process was much slower and less effective. The ability to successfully recover from a slip (thus preventing a fall) is believed to be affected by lower extremity muscle strength and sensory degradation among older individuals. Results from this research can help pinpoint possible intervention strategies for improving dynamic equilibrium among older adults

Biomechanical Analysis of Postural Sway in Elderly Adults on Ramps

This study investigated the effects of ramp angles on postural deviation as a function of age. Five ramp inclinations (1:8, 1:10, 1:12, 1:16, and 1:20) were examined in both ascent and descent directions. Five younger (22 to 28 years) and five older (78 to 88 years) adults participated in the study. Video-based motion analysis was used to measure torso and hip angles while participants walked on an adjustable inclined ramp. Both young and older participants had a significant increase in torso angle across ramp slopes from ascent to descent. In addition, the data indicated that older participants tended to lean to the right while walking while the young participants leaned to the left. Measurements of hip angle revealed that young participants had significantly greater hip movement than older participants and that hip angle decreased significantly as participants transitioned from descent to ascent trials. Based on the data observed, it is possible that ramp descent is more problematic for elderly adults. However, within the ramp conditions evaluated, the data were unable to clearly discriminate between ramp slopes beyond identifying differences between slopes of ascent and descent.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline

Evidence-based clinical practice guideline for the use of pit-and-fissure sealants

AbstractBackgroundThis article presents evidence-based clinical recommendations for the use of pit-and-fissure sealants on the occlusal surfaces of primary and permanent molars in children and adolescents. A guideline panel convened by the American Dental Association (ADA) Council on Scientific Affairs and the American Academy of Pediatric Dentistry conducted a systematic review and formulated recommendations to address clinical questions in relation to the efficacy, retention, and potential side effects of sealants to prevent dental caries; their efficacy compared with fluoride varnishes; and a head-to-head comparison of the different types of sealant material used to prevent caries on pits and fissures of occlusal surfaces.Types of Studies ReviewedThis is an update of the ADA 2008 recommendations on the use of pit-and-fissure sealants on the occlusal surfaces of primary and permanent molars. The authors conducted a systematic search in MEDLINE, Embase, Cochrane Central Register of Controlled Trials, and other sources to identify randomized controlled trials reporting on the effect of sealants (available on the US market) when applied to the occlusal surfaces of primary and permanent molars. The authors used the Grading of Recommendations Assessment, Development, and Evaluation approach to assess the quality of the evidence and to move from the evidence to the decisions.ResultsThe guideline panel formulated 3 main recommendations. They concluded that sealants are effective in preventing and arresting pit-and-fissure occlusal carious lesions of primary and permanent molars in children and adolescents compared with the nonuse of sealants or use of fluoride varnishes. They also concluded that sealants could minimize the progression of noncavitated occlusal carious lesions (also referred to as initial lesions) that receive a sealant. Finally, based on the available limited evidence, the panel was unable to provide specific recommendations on the relative merits of 1 type of sealant material over the others.Conclusions and Practical ImplicationsThese recommendations are designed to inform practitioners during the clinical decision-making process in relation to the prevention of occlusal carious lesions in children and adolescents. Clinicians are encouraged to discuss the information in this guideline with patients or the parents of patients. The authors recommend that clinicians reorient their efforts toward increasing the use of sealants on the occlusal surfaces of primary and permanent molars in children and adolescents

Sealants for preventing and arresting pit-and-fissure occlusal caries in primary and permanent molars

AbstractBackgroundNational Health and Nutrition Examination Survey 2011-2012 data indicated that, in the United States, nearly one-fourth of children and over one-half of adolescents experienced dental caries in their permanent teeth. The purpose of this review was to summarize the available clinical evidence regarding the effect of dental sealants for the prevention and management of pit-and-fissure occlusal carious lesions in primary and permanent molars, compared with a control without sealants, with fluoride varnishes, or with other head-to head comparisons.Type of Studies ReviewedThe authors included parallel and split-mouth randomized controlled trials that included at least 2 years of follow-up, which they identified using MEDLINE (via PubMed), Embase, LILACS, the Cochrane Central Register of Controlled Trials, and registers of ongoing trials. Pairs of reviewers independently conducted the selection of studies, data extraction, risk of bias assessments, and quality of the evidence assessments by using the Grading of Recommendations Assessment, Development and Evaluation approach.ResultsOf 2,869 records screened, the authors determined that 24 articles (representing 23 studies) proved eligible. Moderate-quality evidence suggested that participants who received sealants had a reduced risk of developing carious lesions in occlusal surfaces of permanent molars compared with those who did not receive sealants (odds ratio [OR], 0.15; 95% confidence interval [CI], 0.08-0.27) after 7 or more years of follow-up. When the authors compared studies whose investigators had compared sealants with fluoride varnishes, they found that sealants reduced the incidence of carious lesions after 7 or more years of follow-up (OR, 0.19; 95% CI, 0.07-0.51); however, this finding was supported by low-quality evidence. On the basis of the evidence, the authors could not provide a hierarchy of effectiveness among the studies whose investigators had conducted head-to-head comparisons. The investigators of 2 trials provided information about adverse events, but they did not report any adverse events.Conclusions and Practical ImplicationsAvailable evidence suggests that sealants are effective and safe to prevent or arrest the progression of noncavitated carious lesions compared with a control without sealants or fluoride varnishes. Further research is needed to provide information about the relative merits of the different types of sealant materials