@article{jiang_savage_2009, title={On the existence of symmetric chain decompositions in a quotient of the Boolean lattice}, volume={309}, ISSN={["1872-681X"]}, DOI={10.1016/j.disc.2007.11.036}, abstractNote={We highlight a question about binary necklaces, i.e., equivalence classes of binary strings under rotation. Is there a way to choose representatives of the n-bit necklaces so that the subposet of the Boolean lattice induced by those representatives has a symmetric chain decomposition? Alternatively, is the quotient of the Boolean lattice Bn, under the action of the cyclic group Zn, a symmetric chain order? The answer is known to be yes for all prime n and for composite n≤18, but otherwise the question appears to be open. In this note we describe how it suffices to focus on subposets induced by necklaces with periodic block codes, substantially reducing the size of the problem. We mention a motivating application: determining whether minimum-region rotationally symmetric independent families of n curves exist for all n.}, number={17}, journal={DISCRETE MATHEMATICS}, author={Jiang, Zongliang and Savage, Carla D.}, year={2009}, month={Sep}, pages={5278–5283} }
 @article{shu_jiang_xu_mirka_2007, title={The effect of a knee support on the biomechanical response of the low back}, volume={23}, ISSN={["1065-8483"]}, DOI={10.1123/jab.23.4.275}, abstractNote={Stooping and squatting postures are seen in a number of industries (e.g., agriculture, construction) where workers must work near ground level for extended periods of time. The focus of the current research was to evaluate a knee support device designed to reduce the biomechanical loading of these postures. Ten participants performed a series of sudden loading tasks while in a semisquat posture under two conditions of knee support (no support and fully supported) and two conditions of torso flexion (45 and 60°). A weight was released into the hands of the participants who then came to steady state while maintaining the designated posture. As they performed this task, the EMG responses of the trunk extensors (multifidus and erector spinae) were collected, both during the “sudden loading” phase of the trial as well as the steady weight-holding phase of the trial. As expected, the effects of torso flexion angle showed significant decreases in the activation of the multifidus muscles with greater torso angle (indicating the initiation of the flexion–relaxation response). Interestingly, the results showed that the knee support device had no effect on the activation levels of the sampled muscles, indicating that the loss of the degree of freedom from the ankle joint during the knee support condition had no impact on trunk extensor muscle response. The a priori concern with regard to these supports was that they would tend to focus loading on the low back and therefore would not serve as a potential ergonomic solution for these stooping/semisquatting tasks. Because the results of this study did not support this concern, further development of such an intervention is underway.}, number={4}, journal={JOURNAL OF APPLIED BIOMECHANICS}, author={Shu, Yu and Jiang, Zongliang and Xu, Xu and Mirka, Gary A.}, year={2007}, month={Nov}, pages={275–281} }
 @article{jiang_shu_drum_reid_mirka_2006, title={Effects of age on muscle activity and upper body kinematics during a repetitive forearm supination task}, volume={36}, ISSN={["1872-8219"]}, DOI={10.1016/j.ergon.2006.07.008}, abstractNote={The principal objective of this study was to assess the effects of age on upper extremity muscle activation patterns and upper body kinematics during a forearm supination task. Age-related physiological and biomechanical changes in the musculoskeletal system have been documented in the literature. It was hypothesized that these changes may have an impact on muscle recruitment and work technique (postural/kinematic) employed during work tasks. A simple repetitive forearm supination task was used to evaluate these hypotheses. Twenty subjects (ten in each age group 19–29 and 55–65) performed a series of static and dynamic forearm supination tasks on a work simulator. These exertions were performed at eight different levels of supination torque: 5–40 lb-in in 5 lb-in increments. As the subjects performed the static exertions the activation levels of several key muscles of the upper extremity were captured using surface electromyography. As the subjects performed the dynamic exertions, the motions of the upper body and upper extremity were captured using a magnetic field-based motion analysis system. The results of the static exertions showed that older subjects generated 135% greater trapezius muscle activity (significant at p<0.05 level) but no other muscle group sampled showed a significant difference between the age groups. In the dynamic exertions, age had no effect on upper limb/torso kinematic responses. In both the static and dynamic exertions, supination torque level had a significant impact on muscle activity and kinematics. These results provide empirical evidence that age alone does not have a consistent impact on biomechanical responses during physically demanding work tasks.}, number={11}, journal={INTERNATIONAL JOURNAL OF INDUSTRIAL ERGONOMICS}, author={Jiang, Zongliang and Shu, Yu and Drum, Jonathan and Reid, Stephanie and Mirka, Gary A.}, year={2006}, month={Nov}, pages={951–957} }
 @article{jiang_shin_freeman_reid_mirka_2005, title={A study of lifting tasks performed on laterally slanted ground surfaces}, volume={48}, ISSN={["0014-0139"]}, DOI={10.1080/00140130500123761}, abstractNote={Lifting in most industrial environments is performed on a smooth, level ground surface. There are, however, many outdoor work environments (e.g. agriculture and construction) that require manual material handling activities on variable grade ground surfaces. Quantifying the biomechanical response while lifting under these conditions may provide insight into the aetiology of lifting-related injury. The aim of the current study was to quantify the effect of laterally slanted ground surfaces on the biomechanical response. Ten subjects performed both isometric weight-holding tasks and dynamic lifting exertions (both using a 40% of max load) while standing on a platform that was laterally tilted at 0, 10, 20 and 30° from horizontal. As the subject performed the isometric exertions, the electromyographic (EMG) activity of trunk extensors and knee extensors were collected and during the dynamic lifting tasks the whole body kinematics were collected. The whole body kinematics data were used in a dynamic biomechanical model to calculate the time-dependent moment about L5/S1 and the time-dependent lateral forces acting on the body segments. The results of the isometric weight-holding task show a significant (p < 0.05) effect of slant angle on the normalized integrated EMG values in both the left (increase by 26%) and right (increase by 70%) trunk extensors, indicating a significant increase in the protective co-contraction response. The results of the dynamic lifting tasks revealed a consistent reduction in the peak dynamic L5/S1 moment (decreased by 9%) and an increase in the instability producing lateral forces (increased by 111%) with increasing slant angle. These results provide quantitative insight into the response of the human lifter under these adverse lifting conditions.}, number={7}, journal={ERGONOMICS}, author={Jiang, ZL and Shin, G and Freeman, J and Reid, S and Mirka, GA}, year={2005}, month={Jun}, pages={782–795} }