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  • 1
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    Motion Constraints and Trajectory Planning of a Planar Active Dynamic Balancing Mechanism (2015)
    Hindawi
    Details
    Publication Date: 2015-09-08
    Description: We propose a new solution to the active balancing issue under mechanical structural constraint. A dynamic model of the 3-DOF active balancer is established considering the limitations of the mechanical construction due to the lengths of the sliding rails. A methodology for the collision-avoidance trajectory planning is presented in addition to the normal trajectory planning to design the collision-free active balancing strategy. Numerical examples are presented to illustrate the effect of the parameter constrains as well as verify the effectiveness and necessity of trajectory planning.
    Print ISSN: 1024-123X
    Electronic ISSN: 1563-5147
    Topics: Mathematics , Technology
    Published by Hindawi
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  • 2
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    Improving Top-N Recommendation Performance Using Missing Data (2015)
    Hindawi
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    Publication Date: 2015-09-08
    Description: Recommender systems become increasingly significant in solving the information explosion problem. Data sparse is a main challenge in this area. Massive unrated items constitute missing data with only a few observed ratings. Most studies consider missing data as unknown information and only use observed data to learn models and generate recommendations. However, data are missing not at random. Part of missing data is due to the fact that users choose not to rate them. This part of missing data is negative examples of user preferences. Utilizing this information is expected to leverage the performance of recommendation algorithms. Unfortunately, negative examples are mixed with unlabeled positive examples in missing data, and they are hard to be distinguished. In this paper, we propose three schemes to utilize the negative examples in missing data. The schemes are then adapted with SVD++, which is a state-of-the-art matrix factorization recommendation approach, to generate recommendations. Experimental results on two real datasets show that our proposed approaches gain better top-N performance than the baseline ones on both accuracy and diversity.
    Print ISSN: 1024-123X
    Electronic ISSN: 1563-5147
    Topics: Mathematics , Technology
    Published by Hindawi
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  • 3
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    Epigallocatechin-3-gallate Protects against Hydrogen Peroxide-Induced Inhibition of Osteogenic Differentiation of Human Bone Marrow-Derived Mesenchymal Stem Cells (2016)
    Hindawi
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    Publication Date: 2016-02-10
    Description: Oxidative stress induces bone loss and osteoporosis, and epigallocatechin-3-gallate (EGCG) may be used to combat these diseases due to its antioxidative property. Herein, oxidative stress in human bone marrow-derived mesenchymal stem cells (BM-MSCs) was induced by H2O2, resulting in an adverse effect on their osteogenic differentiation. However, this H2O2-induced adverse effect was nullified when the cells were treated with EGCG. In addition, treatment of BM-MSCs with EGCG alone also resulted in the enhancement of osteogenic differentiation of BM-MSCs. After EGCG treatment, expressions of β-catenin and cyclin D1 were upregulated, suggesting that the Wnt pathway was involved in the effects of EGCG on the osteogenic differentiation of BM-MSCs. This was also confirmed by the fact that the Wnt pathway inhibitor, Dickkopf-1 (DKK-1), can nullify the EGCG-induced enhancement effect on BM-MSC’s osteogenic differentiation. Hence, our results suggested that EGCG can reduce the effects of oxidative stress on Wnt pathway in osteogenic cells, which supported a potentially promising therapy of bone disorders induced by oxidative stress. Considering its positive effects on BM-MSCs, EGCG may also be beneficial for stem cell-based bone repair.
    Electronic ISSN: 1687-9678
    Topics: Medicine
    Published by Hindawi
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  • 4
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    An Optimization Method for the Geolocation Databases of Internet Hosts Based on Machine Learning (2015)
    Hindawi
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    Publication Date: 2015-06-10
    Description: In order to improve the accuracy and robustness of geolocation (geographic location) databases, a method based on machine learning called GeoCop (Geolocation Cop) is proposed for optimizing the geolocation databases of Internet hosts. In addition to network measurement, which is always used by the existing geolocation methods, our geolocation model for Internet hosts is also derived by both routing policy and machine learning. After optimization with the GeoCop method, the geolocation databases of Internet hosts are less prone to imperfect measurement and irregular routing. In addition to three frequently used geolocation databases (IP138, QQWry, and IPcn), we obtain two other geolocation databases by implementing two well-known geolocation methods (the constraint-based geolocation method and the topology-based geolocation method) for constructing the optimized objects. Finally, we give a comprehensive analysis on the performance of our method. On one hand, we use typical benchmarks to compare the performance of these databases after optimization; on the other hand, we also perform statistical tests to display the improvement of the GeoCop method. As presented in the comparison tables, the GeoCop method not only achieves improved performance in both accuracy and robustness but also enjoys less measurements and calculation overheads.
    Print ISSN: 1024-123X
    Electronic ISSN: 1563-5147
    Topics: Mathematics , Technology
    Published by Hindawi
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  • 5
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    Preliminary Study on Hepatocyte-Targeted Phosphorus-31 MRS Using ATP-Loaded Galactosylated Chitosan Oligosaccharide Nanoparticles (2013)
    Hindawi
    Details
    Publication Date: 2013-12-03
    Description: Background. The clinical applications of hepatic phosphorus-31 magnetic resonance spectroscopy (31P MRS) remain to be difficult because the changes of phosphates between normal hepatic tissues and pathological tissues are not so obvious, and furthermore, up to now there is few literature on hepatocyte-targeted 31P MRS. Materials and Methods. The ATP-loaded Gal-CSO (Gal-CSO/ATP) nanoparticles were prepared and the special cellular uptake of them as evaluated by using HepG-2 tumor cells and A549 tumor cells, respectively. Two kinds of cells were incubated with the nanoparticles suspension, respectively. Then were prepared the cell samples and the enhancement efficiency of ATP peaks detected by 31P MRS was evaluated. Results. The cellular uptake rate of Gal-CSO/ATP nanoparticles in HepG-2 cells was higher than that in A549 cells. Furthermore, the enlarged ATP peaks of Gal-CSO/ATP nanoparticles in HepG-2 cells were higher than those in A549 cells in vitro detected by 31P MRS. Conclusions. Gal-CSO/ATP nanoparticles have significant targeting efficiency in hepatic cells in vitro and enhancement efficiency of ATP peaks in HepG-2 cells. Furthermore, 31P MRS could be applied in the research of hepatic molecular imaging.
    Print ISSN: 1687-6121
    Electronic ISSN: 1687-630X
    Topics: Medicine
    Published by Hindawi
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  • 6
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    A Novel Minimal Invasive Mouse Model of Extracorporeal Circulation (2015)
    Hindawi
    Details
    Publication Date: 2015-01-30
    Description: Extracorporeal circulation (ECC) is necessary for conventional cardiac surgery and life support, but it often triggers systemic inflammation that can significantly damage tissue. Studies of ECC have been limited to large animals because of the complexity of the surgical procedures involved, which has hampered detailed understanding of ECC-induced injury. Here we describe a minimally invasive mouse model of ECC that may allow more extensive mechanistic studies. The right carotid artery and external jugular vein of anesthetized adult male C57BL/6 mice were cannulated to allow blood flow through a 1/32-inch external tube. All animals survived 30 min ECC and subsequent 60 min observation. Blood analysis after ECC showed significant increases in levels of tumor necrosis factor α, interleukin-6, and neutrophil elastase in plasma, lung, and renal tissues, as well as increases in plasma creatinine and cystatin C and decreases in the oxygenation index. Histopathology showed that ECC induced the expected lung inflammation, which included alveolar congestion, hemorrhage, neutrophil infiltration, and alveolar wall thickening; in renal tissue, ECC induced intracytoplasmic vacuolization, acute tubular necrosis, and epithelial swelling. Our results suggest that this novel, minimally invasive mouse model can recapitulate many of the clinical features of ECC-induced systemic inflammatory response and organ injury.
    Print ISSN: 0962-9351
    Electronic ISSN: 1466-1861
    Topics: Medicine
    Published by Hindawi
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