1,480 research outputs found

    Seismic Fragility Assessment Of Moment-Resisting Concrete Frame With Setback Under Repeated Earthquake

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    This research study is carried out to analyse the seismic behaviour of 10 types six-storey Moment-Resisting Concrete Frames (MRCFs), namely 1 regular frame and 9 setback frames with different building configurations. The setback buildings were mainly emphasised in this analysis because they are becoming increasingly popular in modern multi-storey building construction due to its functional and aesthetic architecture. Incremental Dynamics Analysis(IDA) have been performed on these frames under three sets of repeated ground motion records. Based on the IDA curve, the Life Safety (LS) performance level will be considered as main guideline in order to develop the fragility curve. The maximum inter-story drift percentages at each story level for all the frames and the location of the plastic hinges for each frames can also be determined clearly through IDA. Based on the IDA curve plotted, the mean and standard deviation of the Peak Ground Acceleration (PGA) at drift 1.5% for the frames were determined in order to develop the fragility curve with the life safety performance level. From the results of the fragility curves, the probability of reaching or exceeding the life safety performance state can be determined. The regular frame showed the lowest probability compared to the other frames. As predicted, it has the better seismic performance as compared to the other frames. Among the setback frames, the Model 6T 6 recorded the highest probability of reaching or exceeding the life safety performance level while Model 6T 3 recorded the lowest probability of reaching or exceeding the life safety performance level under any PGA values. Thus, the Model 6T 3 has the best seismic performance while the Model 6T 6 has the poor seismic performance. Thus, it can be known that the building configuration of the frames governs the seismic performance of the building and thus it should be taken into consideration in the building seismic design

    Experimental Study on the Flexural Behavior of Reinforced Polystyrene Blocks in Concrete Beams

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    A new type of lightweight beam system was recently proposed by embedding polystyrene in beams to improve structural efficiency. This removes the non-performing concrete in the neutral axis and tension region to provide a comparable strength as a solid beam. There are, however, limited studies conducted to investigate the structural behavior of such beams. Therefore, this research presents an experimental investigation to assess the effect of polystyrene shapes in the beams. This involved testing a solid beam and five lightweight beams under flexural load using a four-point load test. The inclusion of polystyrene was estimated to have reduced the self-weight of beams by 8.6% to 11.8% when compared with the solid beam. The results also showed the ellipse polystyrene with a width of 70 mm and height of 50 mm produced the highest effective strength to weight ratio (sw) of 1.12 and performed 12% better than the solid beam. Moreover, the lightweight beams have more weight reduced than the strength, and those with ellipse polystyrene were found to have performed better than circular ones based on first crack load, ultimate load, and effective strength to weight ratio (sw). The beams with ellipse polystyrene allowed better stress distribution and this gave them a higher strength than sphere shape. For industry application, the polystyrene content is recommended to be greater than 10% while the effective strength to weight ratio (sw) of the beam is greater than 1. The successful reduction of the weight without affecting the structural performance has the ability to help in reducing construction costs

    Cyr61/CCN1 Is Regulated by Wnt/β-Catenin Signaling and Plays an Important Role in the Progression of Hepatocellular Carcinoma

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    Abnormal activation of the canonical Wnt signaling pathway has been implicated in carcinogenesis. Transcription of Wnt target genes is regulated by nuclear β-catenin, whose over-expression is observed in Hepatocellular Carcinoma (HCC) tissue. Cyr61, a member of the CCN complex family of multifunctional proteins, is also found over-expressed in many types of tumor and plays dramatically different roles in tumorigenesis. In this study, we investigated the relationship between Cyr61 and β-catenin in HCC. We found that while Cyr61 protein was not expressed at a detectable level in the liver tissue of healthy individuals, its expression level was elevated in the HCC and HCC adjacent tissues and was markedly increased in cancer-adjacent hepatic cirrhosis tissue. Over-expression of Cyr61 was positively correlated with increased levels of β-catenin in human HCC samples. Activation of β-catenin signaling elevated the mRNA level of Cyr61 in HepG2 cells, while inhibition of β-catenin signaling reduced both mRNA and protein levels of Cyr61. We identified two TCF4-binding elements in the promoter region of human Cyr61 gene and demonstrated that β-catenin/TCF4 complex specifically bound to the Cyr61 promoter in vivo and directly regulated its promoter activity. Furthermore, we found that over-expression of Cyr61 in HepG2 cells promoted the progression of HCC xenografts in SCID mice. These findings indicate that Cyr61 is a direct target of β-catenin signaling in HCC and may play an important role in the progression of HCC

    Benefits and risks of the hormetic effects of dietary isothiocyanates on cancer prevention

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    The isothiocyanate (ITC) sulforaphane (SFN) was shown at low levels (1-5 µM) to promote cell proliferation to 120-143% of the controls in a number of human cell lines, whilst at high levels (10-40 µM) it inhibited such cell proliferation. Similar dose responses were observed for cell migration, i.e. SFN at 2.5 µM increased cell migration in bladder cancer T24 cells to 128% whilst high levels inhibited cell migration. This hormetic action was also found in an angiogenesis assay where SFN at 2.5 µM promoted endothelial tube formation (118% of the control), whereas at 10-20 µM it caused significant inhibition. The precise mechanism by which SFN influences promotion of cell growth and migration is not known, but probably involves activation of autophagy since an autophagy inhibitor, 3-methyladenine, abolished the effect of SFN on cell migration. Moreover, low doses of SFN offered a protective effect against free-radical mediated cell death, an effect that was enhanced by co-treatment with selenium. These results suggest that SFN may either prevent or promote tumour cell growth depending on the dose and the nature of the target cells. In normal cells, the promotion of cell growth may be of benefit, but in transformed or cancer cells it may be an undesirable risk factor. In summary, ITCs have a biphasic effect on cell growth and migration. The benefits and risks of ITCs are not only determined by the doses, but are affected by interactions with Se and the measured endpoint

    New measurement of θ13\theta_{13} via neutron capture on hydrogen at Daya Bay

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    This article reports an improved independent measurement of neutrino mixing angle θ13\theta_{13} at the Daya Bay Reactor Neutrino Experiment. Electron antineutrinos were identified by inverse β\beta-decays with the emitted neutron captured by hydrogen, yielding a data-set with principally distinct uncertainties from that with neutrons captured by gadolinium. With the final two of eight antineutrino detectors installed, this study used 621 days of data including the previously reported 217-day data set with six detectors. The dominant statistical uncertainty was reduced by 49%. Intensive studies of the cosmogenic muon-induced 9^9Li and fast neutron backgrounds and the neutron-capture energy selection efficiency, resulted in a reduction of the systematic uncertainty by 26%. The deficit in the detected number of antineutrinos at the far detectors relative to the expected number based on the near detectors yielded sin22θ13=0.071±0.011\sin^22\theta_{13} = 0.071 \pm 0.011 in the three-neutrino-oscillation framework. The combination of this result with the gadolinium-capture result is also reported.Comment: 26 pages, 23 figure

    Evolution of the Reactor Antineutrino Flux and Spectrum at Daya Bay

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    The Daya Bay experiment has observed correlations between reactor core fuel evolution and changes in the reactor antineutrino flux and energy spectrum. Four antineutrino detectors in two experimental halls were used to identify 2.2 million inverse beta decays (IBDs) over 1230 days spanning multiple fuel cycles for each of six 2.9 GWth_{\textrm{th}} reactor cores at the Daya Bay and Ling Ao nuclear power plants. Using detector data spanning effective 239^{239}Pu fission fractions, F239F_{239}, from 0.25 to 0.35, Daya Bay measures an average IBD yield, σˉf\bar{\sigma}_f, of (5.90±0.13)×1043(5.90 \pm 0.13) \times 10^{-43} cm2^2/fission and a fuel-dependent variation in the IBD yield, dσf/dF239d\sigma_f/dF_{239}, of (1.86±0.18)×1043(-1.86 \pm 0.18) \times 10^{-43} cm2^2/fission. This observation rejects the hypothesis of a constant antineutrino flux as a function of the 239^{239}Pu fission fraction at 10 standard deviations. The variation in IBD yield was found to be energy-dependent, rejecting the hypothesis of a constant antineutrino energy spectrum at 5.1 standard deviations. While measurements of the evolution in the IBD spectrum show general agreement with predictions from recent reactor models, the measured evolution in total IBD yield disagrees with recent predictions at 3.1σ\sigma. This discrepancy indicates that an overall deficit in measured flux with respect to predictions does not result from equal fractional deficits from the primary fission isotopes 235^{235}U, 239^{239}Pu, 238^{238}U, and 241^{241}Pu. Based on measured IBD yield variations, yields of (6.17±0.17)(6.17 \pm 0.17) and (4.27±0.26)×1043(4.27 \pm 0.26) \times 10^{-43} cm2^2/fission have been determined for the two dominant fission parent isotopes 235^{235}U and 239^{239}Pu. A 7.8% discrepancy between the observed and predicted 235^{235}U yield suggests that this isotope may be the primary contributor to the reactor antineutrino anomaly.Comment: 7 pages, 5 figure

    A new measurement of antineutrino oscillation with the full detector configuration at Daya Bay

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    We report a new measurement of electron antineutrino disappearance using the fully-constructed Daya Bay Reactor Neutrino Experiment. The final two of eight antineutrino detectors were installed in the summer of 2012. Including the 404 days of data collected from October 2012 to November 2013 resulted in a total exposure of 6.9×\times105^5 GWth_{\rm th}-ton-days, a 3.6 times increase over our previous results. Improvements in energy calibration limited variations between detectors to 0.2%. Removal of six 241^{241}Am-13^{13}C radioactive calibration sources reduced the background by a factor of two for the detectors in the experimental hall furthest from the reactors. Direct prediction of the antineutrino signal in the far detectors based on the measurements in the near detectors explicitly minimized the dependence of the measurement on models of reactor antineutrino emission. The uncertainties in our estimates of sin22θ13\sin^{2}2\theta_{13} and Δmee2|\Delta m^2_{ee}| were halved as a result of these improvements. Analysis of the relative antineutrino rates and energy spectra between detectors gave sin22θ13=0.084±0.005\sin^{2}2\theta_{13} = 0.084\pm0.005 and Δmee2=(2.42±0.11)×103|\Delta m^{2}_{ee}|= (2.42\pm0.11) \times 10^{-3} eV2^2 in the three-neutrino framework.Comment: Updated to match final published versio

    Associations between XPD Asp312Asn Polymorphism and Risk of Head and Neck Cancer: A Meta-Analysis Based on 7,122 Subjects

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    Background: To investigate the association between XPD Asp312Asn polymorphism and head and neck cancer risk through this meta-analysis. Methods: We performed a meta-analysis of 9 published case-control studies including 2,670 patients with head and neck cancer and 4,452 controls. An odds ratio (OR) with a 95 % confidence interval (CI) was applied to assess the association between XPD Asp312Asn polymorphism and head and neck cancer risk. Results: Overall, no significant association between XPD Asp312Asn polymorphism and head and neck cancer risk was found in this meta-analysis (Asn/Asn vs. Asp/Asp: OR = 0.95, 95%CI = 0.80–1.13, P = 0.550, Pheterogeneity = 0.126; Asp/Asn vs. Asp/Asp: OR = 1.11, 95%CI = 0.99–1.24, P = 0.065, P heterogeneity = 0.663; Asn/Asn+Asp/Asn vs. Asp/Asp: OR = 1.07, 95%CI = 0.97–1.19, P = 0.189, P heterogeneity = 0.627; Asn/Asn vs. Asp/Asp+Asp/Asn: OR = 0.87, 95%CI = 0.68–1.10, P = 0.243, Pheterogeneity = 0.089). In the subgroup analysis by HWE, ethnicity, and study design, there was still no significant association detected in all genetic models. Conclusions: This meta-analysis demonstrates that XPD Asp312Asn polymorphism may not be a risk factor for developing head and neck cancer
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