449 research outputs found

    A Temporal Usage Pattern-based Tag Recommendation Approach

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    While social tagging can benefit Internet users managing their resources, it suffers the problems such as diverse and/or unchecked vocabulary and unwillingness to tag. Use of freely new tags and/or reuse of frequent tags have degraded coherence of corresponding resources of each tag that further frustrates people in retrieving information due to cognitive dissonance. Tag recommender systems can recommend users the most relevant tags to the resource they intend to annotate, and drastically transfer the tagging process from generation to recognition to reduce user’s cognitive effort and time. Prior research on tag recommendation has addressed the time-dependence issues of tags by applying a time decaying measure to determine the recurrence probability of a tag according to its recency instead of its usage pattern. In response, this study intends to propose the temporal usage pattern-based tag recommendation technique to consider the usage patterns and temporal characteristic of tags for making recommendations

    Design, Modeling and Development of a Serial Hybrid Motorcycle with HCCI Engine

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    This paper discusses the design, modeling, and development of small motorcycle equipped with a HCCI engine in an series hybrid configuration. A mathematical model was developed using MATLAB/Simulink and used to size the powertrain components and to predict fuel economy. A conventional 125 cc spark ignition engine was modified to run in HCCI combustion mode and integrated into a prototype vehicle. Dual-fuel and external EGR strategies were used to upgrade the engine speed and torque capabilities of the engine to meet the requirements of the powertrain. An electrical generator, hub-motor, battery pack and other power electronics devices were used to form the electrical system for the vehicle. The advantages of the proposed design compared to the original motorcycle with SI engine and CVT transmission are: 1) a reduction in noxious emissions due to the HCCI combustion, and 2) higher fuel economy in city driving because of the HCCI engine and series hybrid powertrain. Fuel economy was measured by driving the motorcycle on a chassis dynamometer using a sequence of ECE-40 driving cycles. The overall fuel economy was measured to be 73.7km/L which represents a 139.3% increase in fuel economy over the baseline vehicle

    The Design and Analysis of Passive Pitch Control for Horizontal Axis Wind Turbine

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    AbstractThe purpose of this thesis is to design and analysis of passive pitch control. Design a mechanics to control different revolution of blade's pitch angle. The use of small wind turbines gradually popularization, but how to overcome the low wind speed start-up and the operation under high wind speed, that is the difficult problems encountered by designers. In order to extend the use and the safe of wind speed, this design is required. This paper is focus on the mechanism design of the passive pitch control for the small horizontal axis wind turbine (HAWT). When the wind speed is fast, the rotation speed is also faster and faster. The system uses centrifugal force to make Pulley disk driven the pitch angle of the blade. It can achieve the effect of passive pitch control. The mechanism is our laboratory's patent. Through the experiments in wind tunnel, it can be observed the variation of the performance curve when the pitch rotation. This system not only successfully operates under high wind speed but also has better performance at low wind speed

    A feeder-free culture using autogeneic conditioned medium for undifferentiated growth of human embryonic stem cells: Comparative expression profiles of mRNAs, microRNAs and proteins among different feeders and conditioned media

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    <p>Abstract</p> <p>Background</p> <p>Human embryonic stem (hES) cell lines were derived from the inner cell mass of human blastocysts, and were cultured on mouse embryonic fibroblast (MEF) feeder to maintain undifferentiated growth, extensive renewal capacity, and pluripotency. The hES-T3 cell line with normal female karyotype was previously used to differentiate into autogeneic fibroblast-like cells (T3HDF) as feeder to support the undifferentiated growth of hES-T3 cells (T3/HDF) for 14 passages.</p> <p>Results</p> <p>A feeder-free culture on Matrigel in hES medium conditioned by the autogeneic feeder cells (T3HDF) was established to maintain the undifferentiated growth of hES-T3 cells (T3/CMHDF) for 8 passages in this investigation. The gene expression profiles of mRNAs, microRNAs and proteins between the undifferentiated T3/HDF and T3/CMHDF cells were shown to be very similar, and their expression profiles were also found to be similar to those of T3/MEF and T3/CMMEF cells grown on MEF feeder and feeder-free Matrigel in MEF-conditioned medium, respectively. The undifferentiated state of T3/HDF and T3/CMHDF as well as T3/MEF andT3/CMMEF cells was evidenced by the very high expression levels of "stemness" genes and low expression levels of differentiation markers of ectoderm, mesoderm and endoderm in addition to the strong staining of OCT4 and NANOG.</p> <p>Conclusion</p> <p>The T3HDF feeder and T3HDF-conditioned medium were able to support the undifferentiated growth of hES cells, and they would be useful for drug development and toxicity testing in addition to the reduced risks of xenogeneic pathogens when used for medical applications such as cell therapies.</p

    Inhibition of gap junctional Intercellular communication in WB-F344 rat liver epithelial cells by triphenyltin chloride through MAPK and PI3-kinase pathways

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    <p>Abstract</p> <p>Background</p> <p>Organotin compounds (OTCs) have been widely used as stabilizers in the production of plastic, agricultural pesticides, antifoulant plaints and wood preservation. The toxicity of triphenyltin (TPT) compounds was known for their embryotoxic, neurotoxic, genotoxic and immunotoxic effects in mammals. The carcinogenicity of TPT was not well understood and few studies had discussed the effects of OTCs on gap junctional intercellular communication (GJIC) of cells.</p> <p>Method</p> <p>In the present study, the effects of triphenyltin chloride (TPTC) on GJIC in WB-F344 rat liver epithelial cells were evaluated, using the scrape-loading dye transfer technique.</p> <p>Results</p> <p>TPTC inhibited GJIC after a 30-min exposure in a concentration- and time-dependent manner. Pre-incubation of cells with the protein kinase C (PKC) inhibitor did not modify the response, but the specific MEK 1 inhibitor PD98059 and PI3K inhibitor LY294002 decreased substantially the inhibition of GJIC by TPTC. After WB-F344 cells were exposed to TPTC, phosphorylation of Cx43 increased as seen in Western blot analysis.</p> <p>Conclusions</p> <p>These results show that TPTC inhibits GJIC in WB-F344 rat liver epithelial cells by altering the Cx43 protein expression through both MAPK and PI3-kinase pathways.</p

    Neuronal Activity Stimulated by Liquid Substrates Injection at Zusanli (ST36) Acupoint: The Possible Mechanism of Aquapuncture

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    Aquapuncture is a modified acupuncture technique and it is generally accepted that it has a greater therapeutic effect than acupuncture because of the combination of the acupoint stimulation and the pharmacological effect of the drugs. However, to date, the mechanisms underlying the effects of aquapuncture remain unclear. We hypothesized that both the change in the local spatial configuration and the substrate stimulation of aquapuncture would activate neuronal signaling. Thus, bee venom, normal saline, and vitamins B1 and B12 were injected into a Zusanli (ST36) acupoint as substrate of aquapuncture, whereas a dry needle was inserted into ST36 as a control. After aquapuncture, activated neurons expressing Fos protein were mainly observed in the dorsal horn of the spinal cord in lumbar segments L3–5, with the distribution nearly identical among all groups. However, the bee venom injection induced significantly more Fos-expressing neurons than the other substrates. Based on these data, we suggest that changes in the spatial configuration of the acupoint activate neuronal signaling and that bee venom may further strengthen this neuronal activity. In conclusion, the mechanisms for the effects of aquapuncture appear to be the spatial configuration changes occurring within the acupoint and the ability of injected substrates to stimulate neuronal activity

    The relationship between gallbladder status and recurrent biliary complications in patients with choledocholithiasis following endoscopic treatment

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    AbstractBackgroundEndoscopic methods are currently the treatment of choice for patients with common bile duct (CBD) stones, but subsequent management of the intact gallbladder for patients following endoscopic treatment is still controversial. The primary aim of this study was to discover the association between gallbladder status and recurrent biliary complications for patients with CBD stones after endoscopic treatment. Additionally, we also sought to determine risk factors for recurrent biliary complications in these patients.MethodsThe records of 1625 patients with CBD stones following endoscopic treatment were reviewed. A total of 681 patients were enrolled and subsequently categorized into four groups: Group 1 (n = 201), calculous gallbladder; Group 2 (n = 140), acalculous gallbladder; Group 3 (n = 175), elective cholecystectomy after endoscopic treatment; and Group 4 (n = 165), prior cholecystectomy. The basic demographics and recurrent biliary complications during follow-up among these four groups were analyzed by Chi-square test, ANOVA, Kaplan-Meier analysis, and log-rank test.ResultsDuring the median follow-up period of 34 months, 133 patients (20%) with recurrent biliary complications were identified. The recurrence rates of Groups 1, 2, 3, and 4 were 29%, 11%, 15%, and 19%, respectively. Kaplan-Meier analysis showed that patients with calculous gallbladder had a significantly higher rate of recurrent biliary complication. In multivariate analysis, patients with a history of cirrhosis, juxta-papillary diverticulum, calculous gallbladder, CBD size ≥1.5 cm, and endoscopic management with endoscopic sphincterotomy were at a higher risk for developing biliary complications (p = 0.029, p = 0.039, p < 0.001, p = 0.002, p = 0.021, respectively.)ConclusionPatients with cholecystolithiasis and CBD stones had a higher incidence of recurrent biliary complications. For some of these patients, elective cholecystectomy following endoscopic treatment may be considered. However, routine elective cholecystectomy in patients with normal gallbladder is not appropriate because of the low recurrence of biliary complications. Whether gallbladder function affects the biliary clearance and biliary complications requires further research
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