Adaptive Tuning of Robotic Polishing Skills based on Force Feedback Model

Acquiring human skills offers an efficient approach to tackle complex task planning challenges. When performing a learned skill model for a continuous contact task, such as robot polishing in an uncertain environment, the robot needs to be able to adaptively modify the skill model to suit the environment and perform the desired task. The environmental perturbation of the polishing task is mainly reflected in the variation of contact force. Therefore, adjusting the task skill model by providing feedback on the contact force deviation is an effective way to meet the task requirements. In this study, a phase-modulated diagonal recurrent neural network (PMDRNN) is proposed for force feedback model learning in the robotic polishing task. The contact between the tool and the workpiece in the polishing task can be considered a dynamic system. In comparison to the existing feedforward neural network phase-modulated neural network (PMNN), PMDRNN combines the diagonal recurrent network structure with the phase-modulated neural network layer to improve the learning performance of the feedback model for dynamic systems. Specifically, data from real-world robot polishing experiments are used to learn the feedback model. PMDRNN demonstrates a significant reduction in the training error of the feedback model when compared to PMNN. Building upon this, the combination of PMDRNN and dynamic movement primitives (DMPs) can be used for real-time adjustment of skills for polishing tasks and effectively improve the robustness of the task skill model. Finally, real-world robotic polishing experiments are conducted to demonstrate the effectiveness of the approach.Comment: This paper has been accepted by The 2023 IEEE International Conference on Robotics and Biomimetics (IEEE ROBIO 2023

Identification of Human Fibroblast Cell Lines as a Feeder Layer for Human Corneal Epithelial Regeneration

There is a great interest in using epithelium generated in vitro for tissue bioengineering. Mouse 3T3 fibroblasts have been used as a feeder layer to cultivate human epithelia including corneal epithelial cells for more than 3 decades. To avoid the use of xeno-components, we evaluated human fibroblasts as an alternative feeder supporting human corneal epithelial regeneration. Five human fibroblast cell lines were used for evaluation with mouse 3T3 fibroblasts as a control. Human epithelial cells isolated from fresh corneal limbal tissue were seeded on these feeders. Colony forming efficiency (CFE) and cell growth capacity were evaluated on days 5–14. The phenotype of the regenerated epithelia was evaluated by morphology and immunostaining with epithelial markers. cDNA microarray was used to analyze the gene expression profile of the supportive human fibroblasts. Among 5 strains of human fibroblasts evaluated, two newborn foreskin fibroblast cell lines, Hs68 and CCD1112Sk, were identified to strongly support human corneal epithelial growth. Tested for 10 passages, these fibroblasts continually showed a comparative efficiency to the 3T3 feeder layer for CFE and growth capacity of human corneal epithelial cells. Limbal epithelial cells seeded at 1×104 in a 35-mm dish (9.6 cm2) grew to confluence (about 1.87–2.41×106 cells) in 12–14 days, representing 187–241 fold expansion with over 7–8 doublings on these human feeders. The regenerated epithelia expressed K3, K12, connexin 43, p63, EGFR and integrin β1, resembling the phenotype of human corneal epithelium. DNA microarray revealed 3 up-regulated and 10 down-regulated genes, which may be involved in the functions of human fibroblast feeders. These findings demonstrate that commercial human fibroblast cell lines support human corneal epithelial regeneration, and have potential use in tissue bioengineering for corneal reconstruction

Cloning and Expression of β-Defensin from Soiny Mullet (Liza haematocheila), with Insights of its Antibacterial Mechanism.

Beta-defensins are important part of innate immunity of fish, which are the first defense line against invading pathogens. In this study, the β-defensin (Lhβ-defensin) gene was cloned from spleen tissue of soiny mullet (Liza haematocheila). Lhβ-defensin cDNA was 747 bp in length, encoding 63 amino acids. Sequence alignment revealed that Lhβ-defensin contained six conserved cysteine residues and shared 97.5% sequence identities with grouper (Epinephelus coioides) β-defensin. Realtime PCR revealed that Lhβ-defensin was highest expressed in the immune related organs, such as spleen, kidney and gut of healthy fish. Following Streptococcus dysgalactiae infection, Lhβ-defensin was up-regulated in immune related organs, e.g. 17.6-fold in spleen and 10.87-fold in gut at 24 h post infection (hpi). Lhβ-defensin possessed a monomeric structure of a three-stranded anti-parallel β-sheet and an α-helix stabilized by three disulfide bonds formed by Cys30-Cys58, Cys36-Cys52, and Cys40-Cys59. In addition to the experimental work, computer simulation was also carried out to determine the possible conformation of β-defensin and its interaction with palmitoyloleoylphosphatidylglycerol (POPG), a model of bacteria membrane. The Lhβ-defensin was found to form dimeric structure stabilized by the van der Waals contacts of Leu35 and Cys37 in two anti-parallel β1-strands and the cation-π interaction between Tyr32 and Arg54 respectively in the two β1-strands. The most important interactions between β-defensin and membrane are the electrostatic interactions between Arg residues in β-defensin and head group of POPG bilayer as well as hydrogen bond interactions between them. Our results were useful for further understanding the potential mechanism of antimicrobial property of fish β-defensins

How can integrated Space–Air–Ground observation contribute in aboveground biomass of shrub plants estimation in shrub-encroached Grasslands?

Shrub encroachment in grassland has become an ecological issue of mounting concern. Accordingly, an accurate estimation of aboveground biomass (AGB) of shrub vegetation is the basis for a sound assessment and in-depth understanding of carbon cycling in shrub-encroached grassland ecosystems. Yet the relatively low stature of plants in the shrub community, coupled with the high spatial heterogeneity of their distribution, contributes substantially to greater uncertainty in remote sensing estimation of shrub vegetation’s AGB. This study proposes a space–air-ground integrated approach to accurately estimate the AGB of shrub vegetation in shrub-encroached grassland ecosystems. The results showed that, at the UAV scale, the estimation of AGB for a monoculture shrub was highly dependent on planar geometric features. Based on the orthorectified images obtained from unmanned aerial vehicles (UAVs), four planar geometric features of shrub plants, namely crown area (S), crown perimeter (C), long-to-short crown dimension ratio (A1, A2), were retained as the most crucial predictors for AGB estimation. Among the 102 features related to vertical structure extracted via Light Detection and Ranging (LiDAR), only the crown height variation and the first layer’s density variable were retained. Utilizing the mentioned features and a random forest regression, the AGB prediction model for the shrub Caragana microphylla performed remarkably well, in having an R2 value of 0.84 and an RMSE of 310.14 g/plant. At the satellite scale, there was significant nonlinear relationship between the AGB of the shrubs and the band, texture, and index features extracted from GF-6 imagery. The derived AGB estimation model based on the Random Forest method demonstrates higher accuracy (R2 = 0.81, RMSE = 14.61 g/m2, MAE = 11.26 g/m2) than the linear stepwise regression (SR) and partial least squares regression (PLSR) models. Notably, the green band reflectance was retained in all three modeling approaches despite pronounced differences in their selected features uses. Yet both NDVIre1 and NDREI indices with red-edge bands were more important, suggesting the red-edge bands of GF-6 can serve as an ideal tool for remote sensing investigations of the AGB of shrub in shrub-encroached grasslands. This study provides technical and scientific support for quantitative assessments of shrub AGB in arid and semi-arid grassland regions

Diet diversity and nutritional status among adults in southwest China.

BACKGROUND:With rapid urbanization in the past decades, diet diversity continues to increase in China. The present cross-sectional study aims to explore the association between dietary diversity and nutritional status among adults in southwest China. METHODS:This study used data from 2011-2012 National Nutritional Survey in Yunnan Province, southwest China (N = 1105).Data of three consecutive 24-hour dietary recalls were used to calculate dietary diversity scores (DDS) and nutrient adequacy ratio (NAR). Body mass index and waist circumference were used to determine nutritional status. Surveylogistic procedure of SAS 9.2 software was used to examine the association between DDS and obesity by estimating odds ratio (OR) and 95% confidence intervals (CI). RESULTS:The mean DDS was 5.2 (SD 1.1) out of nine points. Being female, younger age, belonging to Han ethnicity, having higher educational level and household income were positively associated with DDS (all P<0.05). As DDS increased, consumption also increased in most food groups except grains and vegetables. People with medium and high DDS (DDS = 5 and DDS ≥6, respectively) ingested more energy than the recommended quantity(NAR = 1.1 and 1.2, respectively). However, the intakes of Calcium and Vitamin A were seriously inadequate even for people with high DDS (NAR≤0.5). With potential confounders adjusted, people with medium and high DDS were at higher risk of general and central obesity than people with DDS ≤4 (OR = 1.4-1.9, P<0.01). CONCLUSIONS:Our data indicated that high DDS was associated with excessive energy intake and obesity among adults in southwest China. Although dietary diversity is widely recommended, public health messages should give less emphasis on dietary diversity

Dietary Patterns in Relation to General and Central Obesity among Adults in Southwest China

Dietary patterns represent a broader picture of food consumption, and are better correlated with a variety of health outcomes. However, few studies have been conducted to explore the associations between dietary patterns and obesity in Southwest China. Data from the 2010–2012 National Nutrition Survey in the province of Yunnan, Southwest China, were analyzed (n = 1604, aged 18–80 years). Dietary data were collected using the 24 h dietary recall over three consecutive days. Height, weight, and waist circumference were measured following standard methods. Exploratory factor analysis was used to identify dietary patterns. Logistic regression was used to explore the association between dietary patterns and obesity. Three distinct dietary patterns were identified, which were labeled as traditional, modern, and tuber according to their key components. With potential confounders adjusted, adults in the highest quartile of the modern pattern were at higher risk of general and central obesity (odds ratio (OR) 1.95, 95% confidence interval (CI) 1.15–3.48; OR 2.01, 95% CI 1.37–2.93). In contrast, adults in the highest quartile of the tuber pattern were at lower risk of general and central obesity (OR 0.34, 95% CI 0.15–0.61; OR 0.64, 95% CI 0.43–0.95) but at higher risk of underweight (OR 2.57, 95% CI 1.20–6.45). No significant association was found between the traditional pattern and obesity. Moreover, dietary pattern differences occurred due to the differences in socio-demographic characteristics. In conclusion, the modern dietary pattern was positively, and the tuber pattern negatively, associated with general and central obesity among adults in Southwest China

Research on mechanism change of temperature effect on dephosphorization in the bottom-blown O2–CaO process of semi-steelmaking

In semi-steelmaking, the bottom-blown O2–CaO process is employed to achieve high efficiency dephosphorization. However, there is little research on the requirements for smelting parameters. In this paper, the mechanism changes of temperature effect on dephosphorization are studied by the industrial tests in a 300 t dephosphorization converter. Firstly, the influences of temperature on the equilibrium constant (KP), CaO melting ratio (K) and slag viscosity (ƞ) were analyzed. KP decreases, K increases and ƞ decreases to stability with increasing temperature. The dephosphorization effect is better than the conventional process' even at higher ƞ, because the CaO powder has melted and P is mostly removed during the process of fire-spot zone upward floatation. Hence, the requirements for slagging with good fluidity are reduced. Then, the relationships between the three factors and phosphorus partition between slag and hot metal (LP) were investigated by the correlation analysis. The importance order in the bottom-blown O2–CaO process is: lgKP＞η, it demonstrates that the melting of CaO powder doesn't affect dephosphorization. While the influence order in the conventional process is: K＞η＞lgKP. Finally, we summarize the dephosphorization reaction in the bottom-blown O2–CaO process includes transient reaction accounts for approximately 86% and continuous reaction with about 14%. The process of CaO upward floatation plays major roles in dephosphorization. Based on above results, the temperature requirement of molten steel for dephosphorization becomes lower. The industrial tests show the optimum temperature range for dephosphorization decreases from 1593-1603 K to 1573–1583 K, which validate the conclusion

Transcription Factor TCF4 Maintains the Properties of Human Corneal Epithelial Stem Cells

TCF4, a key transcription factor of Wnt signaling system, has been recently found to be essential for maintaining stem cells. However, its signaling pathway is not well elucidated. This study was to explore the functional roles and signaling pathway of TCF4 in maintaining adult stem cell properties using human corneal epithelial stem cells as a model. With immunofluorescent staining and real-time polymerase chain reaction, we observed that TCF4 was exclusively expressed in the basal layer of human limbal epithelium where corneal epithelial stem cells reside. TCF4 was found to be well colocalized with ABCG2 and p63, two recognized epithelial stem/progenitor cell markers. Using in vitro culture models of primary human corneal epithelial cells, we revealed that TCF4 mRNA and protein were upregulated by cells in exponential growth stage, and RNA interference by small interfering RNA-TCF4 (10-50 nM) transfection blocked TCF4 signaling and suppressed cell proliferation as measured by WST-1 assay. TCF4 silence was found to be accompanied by downregulated proliferation-associated factors p63 and survivin, as well as upregulated cyclin-dependent kinase inhibitor 1C (p57). By creating a wound healing model in vitro, we identified upregulation and activation of beta-catenin/TCF4 with their protein translocation from cytoplasm to nuclei, as evaluated by reverse transcription-quantitative real-time polymerase chain reaction, immunostaining, and Western blotting. Upregulated p63/survivin and downregulated p57 were further identified to be TCF4 downstream molecules that promote cell migration and proliferation in wound healing process. These findings demonstrate that transcription factor TCF4 plays an important role in determining or maintaining the phenotype and functional properties of human corneal epithelial stem cells. STEM CELLS 2012; 30:753761DOD CDMRP [FY06 PR064719]; NIH [EY11915]; National Natural Science Foundation of China [30901634]; Fight for Sight; Research to Prevent Blindness, Oshman Foundatio