ABSTRACT
Objective:To solve the issue regarding a low correlation between visual and haptic feedback provided by the current upper-limb rehabilitation training system, this study was implemented based on the end-effector based upper-limb rehabilitation robot developed in the lab. A novel visual and haptic feedback fusion technology based on force tracking was investigated and its effect on upper-limb training was also studied. Methods:Based on the force model constructed in a virtual environment, two types of haptic feedbacks correlated to the visual feedback were designed, including the repulsive force when two objects getting close and the friction force when the object moving above medium surfaces. The haptic feedback constructed in the virtual environment was delivered to the trainees by using force tracking based on robot controlling algorithm. Eight health subjects were recruited and trained with and without feedback fusion. In the training process, the actual and expected haptic feedbacks as well as the surface electromyography (EMG) signals from anterior deltoid, posterior deltoid, biceps, and triceps were collected. The root means square error (RMSE) between the actual and expected haptic feedback was calculated under the feedback fusion training mode to characterize the force tracking-based multi-sensory feedback fusion technology. The integrated EMG values (iEMG) and EMG amplitudes per unit time (EMG/T) under two training modes were measured to explore the effect of feedback fusion technology on the upper-limb motor training. Results:Under feedback fusion training mode, the RMSE between actual and expected haptic feedback was (0.757±0.171) N. The values of iEMG from four muscles were significantly higher (|t| > 7.965, P < 0.001), and the values of EMG/T from the biceps, triceps and anterior deltoid were significantly larger under feedback fusion training mode than under the training mode without feedback fusion. Conclusion:The proposed upper-limb rehabilitation robot training system could accurately transmit the haptic feedback constructed under the virtual environment to the trainees. This system could increase the stimulation to trainees' peripheral nervous function through visual and haptic feedback fusion as well as increase the trainees' training effort. The advantages of force tracking-based visual and haptic feedback fusion technology are to freely construct the force model under the virtual environment and the haptic feedback mode is not constrained by the spatial position. Moreover, two or more types of force models can be superimposed in the same spatial position by using this technology that could improve the matching effect between haptic feedback and visual feedback under a virtual environment. The trainees' motor rehabilitation interest could be stimulated and the experience feeling of human-robot interaction could also be enhanced.
ABSTRACT
<p><b>OBJECTIVE</b>To explore the association between polymorphisms in the DNA repair gene, xeroderma pigmentosum group D (XPD), and development of hepatocellular carcinoma (HCC) in the Chinese population by performing a systematic review of the previously published clinical data.</p><p><b>METHOD</b>A comprehensive literature search of the BIOSIS Previews and PubMed databases was carried out to identify all case-control studies of XPD polymorphisms and HCC risk. Meta-analysis was conducted to calculate the pooled odds ratios (ORs) with 95% confidence intervals (CIs) of developing HCC for carriers of the various XPD polymorphisms.</p><p><b>RESULTS</b>Six case-control studies were selected for this meta-analysis, and comprised a total of 3424 HCC cases and 3636 controls. The pooled ORs (95% CIs) of XPD codon 751 and 312 allelomorphs were 1.25 (0.70 to 2.24) and 0.85 (0.58 to 1.25), respectively. Compared with the XPD wild-type homozygote Lys/Lys genotype of codon 751, the pooled OR (95% CI) of Lys/G1n + Gln/Gln genotypes for HCC risk was 1.31 (0.71 to 2.42). Compared with the XPD wild-type homozygote Asp/Asp genotype of codon 312, the pooled OR (95% CI) of Asp/Asn + Asn/Asn genotypes for HCC risk was 1.19 (0.73 to 1.95).</p><p><b>CONCLUSION</b>Polymorphisms in the XPD codons 751 and 312 are not associated with HCC risk in the Chinese population.</p>