76 research outputs found

    Failure Mechanisms and Local Scour at Coastal Structures induced by Tsunamis

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    On March 11 2011, an exceptionally large tsunami event was triggered by a massive earthquake offshore, the northeast coast of Japan, which affected coastal infrastructure such as seawalls, coastal dikes and breakwaters in the Tohoku region. Such infrastructure was built to protect against the Level 1 tsunamis that previously hit the region, but not for events as significant as the 2011 Tohoku tsunami, which was categorized as a Level 2 tsunami [Shibayama et al. 2013]. The failure mechanisms of concrete-armoured dikes, breakwaters and seawalls due to Level 2 tsunamis are still not fully understood by researchers and engineers. This paper investigates the failure modes and mechanisms of damaged coastal structures in Miyagi and Fukushima Prefectures, following the authors' post-disaster field surveys carried out between 2011 and 2013. Six significant failure mechanisms were identified for the coastal dikes and seawalls affected by this tsunami: 1) Leeward toe scour failure, 2) Crown armour failure, 3) Leeward slope armour failure, 4) Seaward toe and armour failure, 5) Overturning failure, and 6) Parapet wall failure, in which leeward toe scour being recognized as the major failure mechanism in most surveyed locations. The authors also propose a simple practical mathematical model for predicting the scour depth at the leeward toe of the coastal dikes, by considering the effects of the tsunami hydrodynamics, the soil properties and the type of structure. The key advantage of this model is that it depends entirely on quantities that are measurable in the field. Furthermore this model was further refined by conducting a series of hydraulic model experiments aimed to understand the governing factors of the leeward toe scour failure. Finally, based on the results obtained, key recommendations are given for the design of resilient coastal defence structures that can survive a level 2 tsunami event

    Molecular Biomarkers of Vascular Dysfunction in Obstructive Sleep Apnea

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    Untreated and long-lasting obstructive sleep apnea (OSA) may lead to important vascular abnormalities, including endothelial cell (EC) dysfunction, hypertension, and atherosclerosis. We observed a correlation between microcirculatory reactivity and endothelium-dependent release of nitric oxide in OSA patients. Therefore, we hypothesized that OSA affects (micro)vasculature and we aimed to identify vascular gene targets of OSA that could possibly serve as reliable biomarkers of severity of the disease and possibly of vascular risk. Using quantitative RT-PCR, we evaluated gene expression in skin biopsies of OSA patients, mouse aortas from animals exposed to 4-week intermittent hypoxia (IH; rapid oscillations in oxygen desaturation and reoxygenation), and human dermal microvascular (HMVEC) and coronary artery endothelial cells (HCAEC) cultured under IH. We demonstrate a significant upregulation of endothelial nitric oxide synthase (eNOS), tumor necrosis factor-alpha-induced protein 3 (TNFAIP3; A20), hypoxia-inducible factor 1 alpha (HIF-1α?? and vascular endothelial growth factor (VEGF) expression in skin biopsies obtained from OSA patients with severe nocturnal hypoxemia (nadir saturated oxygen levels [SaO2]<75%) compared to mildly hypoxemic OSA patients (SaO2 75%–90%) and a significant upregulation of vascular cell adhesion molecule 1 (VCAM-1) expression compared to control subjects. Gene expression profile in aortas of mice exposed to IH demonstrated a significant upregulation of eNOS and VEGF. In an in vitro model of OSA, IH increased expression of A20 and decreased eNOS and HIF-1α expression in HMVEC, while increased A20, VCAM-1 and HIF-1αexpression in HCAEC, indicating that EC in culture originating from distinct vascular beds respond differently to IH stress. We conclude that gene expression profiles in skin of OSA patients may correlate with disease severity and, if validated by further studies, could possibly predict vascular risk in OSA patients

    Chronic hepatitis B: whom to treat and for how long? Propositions, challenges, and future directions

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    Recent guidelines of the American Association for the Study of Liver Diseases, the European Association for the Study of the Liver, and the Asian Pacific Association for the Study of the Liver 2008 update of the “Asian-Pacific consensus statement on the management of chronic hepatitis B” offer comprehensive recommendations for the general management of chronic hepatitis B (CHB). These recommendations highlight preferred approaches to the prevention, diagnosis, and treatment of CHB. Nonetheless, the results of recent studies have led to an improved understanding of the disease and a belief that current recommendations on specific therapeutic considerations, including CHB treatment initiation and cessation criteria, particularly in patient populations with special circumstances, can be improved. Twelve experts from the Asia-Pacific region formed the Asia-Pacific Panel Recommendations for the Optimal Management of Chronic Hepatitis B (APPROACH) Working Group to review, challenge, and assess relevant new data and inform future updates of CHB treatment guidelines. The significance of and controversy about reported findings were discussed and debated in an expert meeting of the Working Group in Beijing, China, in November 2008. This review paper attempts to identify areas requiring improved CHB management and provide suggestions for future guideline updates, with special emphasis on treatment initiation and duration

    Measurement of the Bs Lifetime in Fully and Partially Reconstructed Bs -> Ds- (phi pi-)X Decays in pbar-p Collisions at sqrt(s) = 1.96 TeV

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    We present a measurement of the Bs lifetime in fully and partially reconstructed Bs -> Ds(phi pi)X decays in 1.3 fb-1 of pbar-p collisions at sqrt(s) = 1.96 TeV collected by the CDF II detector at the Fermilab Tevatron. We measure tau(Bs) = 1.518 +/- 0.041 (stat.) +/- 0.027 (syst.) ps. The ratio of this result and the world average B0 lifetime yields tau(Bs)/tau(B0) = 0.99 +/-0.03, which is in agreement with recent theoretical predictions.Comment: submitted to Phys. Rev. Let

    Observation of the Y(4140)Y(4140) structure in the J/ψ ϕJ/\psi\,\phi Mass Spectrum in B±→J/ψ ϕKB^\pm\to J/\psi\,\phi K cays

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    The observation of the Y(4140)Y(4140) structure in B±→J/ψ ϕK±B^\pm\rightarrow J/\psi\,\phi K^\pm decays produced in pˉp\bar{p} p collisions at \sqrt{s}=1.96~\TeV is reported with a statistical significance greater than 5 standard deviations. A fit to the J/ψ ϕJ/\psi\,\phi mass spectrum is performed assuming the presence of a Breit-Wigner resonance. The fit yields a signal of 19−5+619^{+6}_{-5} resonance events, and resonance mass and width of 4143.4^{+2.9}_{-3.0}(\mathrm{stat})\pm0.6(\mathrm{syst})~\MeVcc and 15.3^{+10.4}_{-6.1}(\mathrm{stat})\pm2.5(\mathrm{syst})~\MeVcc respectively. The parameters of this resonance-like structure are consistent with values reported from an earlier CDF analysis.Comment: 7 pages, 2 figures, submited to Phys. Rev. Let

    Inter-model diversity of Arctic amplification caused by global warming and its relationship with the Inter-tropical Convergence Zone in CMIP5 climate models

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    Surface-based Arctic amplification (AA) has experienced a remarkable increase in recent decades. Therefore, it is important to understand how Arctic warming might change in response to global warming. By analyzing the Coupled Model Intercomparison Project Phase 5 (CMIP5) multi-model dataset, we examine how AA correlates with changes in tropical Pacific precipitation in response to global warming. It is found that that the changes in the latitudinal position of the Inter-tropical Convergence Zone (ITCZ) are associated to the simulated AA strength in the CMIP5 climate models. Specifically, AA tends to be stronger (weaker) in models where the ITCZ shifts relatively more northward (southward). Further analysis indicates that the inter-model diversity of AA strength in the CMIP5 climate models is related to the changes in large-scale atmospheric circulation associated with the meridional shift of the ITCZ. These results emphasize a close relationship between AA and changes in tropical Pacific precipitation in response to global warming. ? 2016, Springer-Verlag Berlin Heidelberg.111Nsciescopu

    Control of Breathing

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    - Visually grasp how sleep affects each body system thanks to a full-color compendium that correlates the physiology of sleep with the relevant findings.- Determine the best and most up-to-date drug therapy with information about the latest drugs available as well as those in clinical trials.- Compare your patients’ polysomnograms to a wealth of high-quality recordings taken from the latest machines used by institutions around the world.- Score, interpret, and diagnose sleep disorders employing the scoring rules from the latest AASM scoring manual

    Role of the upper ocean structure in the response of ENSO-like SST variability to global warming

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    ISI Document Delivery No.: 629YQ Times Cited: 4 Cited Reference Count: 58 Cited References: An SI, 2008, J CLIMATE, V21, P3, DOI 10.1175/2007JCLI1500.1 An S-I, 2000, GEOPHYS RES LETT, V27, P1573 An SI, 2000, J CLIMATE, V13, P2044, DOI 10.1175/1520-0442(2000)0132.0.CO;2 An SI, 2005, J CLIMATE, V18, P2617, DOI 10.1175/JCLI3433.1 An SI, 2004, J CLIMATE, V17, P2399, DOI 10.1175/1520-0442(2004)0172.0.CO;2 Annamalai H, 2007, J CLIMATE, V20, P1071, DOI 10.1175/JCL14035.1 BELMADANI A, 2010, J CLIM IN PRESS CANE MA, 1976, J MAR RES, V34, P629 Capotondi A, 2006, OCEAN MODEL, V15, P274, DOI 10.1016/j.ocemod.2006.02.004 Collins M, 2005, CLIM DYNAM, V24, P89, DOI 10.1007/s00382-004-0478-x Collins M, 2000, GEOPHYS RES LETT, V27, P3509, DOI 10.1029/2000GL011747 Delworth TL, 2006, J CLIMATE, V19, P643, DOI 10.1175/JCLI3629.1 Dewitte B, 2007, J CLIMATE, V20, P2002, DOI 10.1175/JCL14110.1 Dewitte B, 2007, J CLIMATE, V20, P1035, DOI 10.1175/JCLI4060.1 Dewitte B., 2000, Journal of Climate, V13, DOI 10.1175/1520-0442(2000)0132.0.CO;2 Dewitte B, 1996, J CLIMATE, V9, P1188, DOI 10.1175/1520-0442(1996)0092.0.CO;2 DiNezio PN, 2009, J CLIMATE, V22, P4873, DOI 10.1175/2009JCLI2982.1 Fedorov AV, 2000, SCIENCE, V288, P1997, DOI 10.1126/science.288.5473.1997 Guilyardi E, 2004, J CLIMATE, V17, P4623, DOI 10.1175/JCLI-3260.1 Guilyardi E, 2006, CLIM DYNAM, V26, P329, DOI 10.1007/s00382-005-0084-6 Guilyardi E, 2009, B AM METEOROL SOC, V90, P325, DOI 10.1175/2008BAMS2387.1 HALPERN D, 1995, J GEOPHYS RES, V100, P1525 HIRST AC, 1986, J ATMOS SCI, V43, P606, DOI 10.1175/1520-0469(1986)0432.0.CO;2 IMADA U, 2006, SOLA, V2, P164 Jin FF, 2003, GEOPHYS RES LETT, V30, DOI 10.1029/2002GL015983 Kirtman BP, 1997, J CLIMATE, V10, P1690, DOI 10.1175/1520-0442(1997)0102.0.CO;2 Kirtman BP, 2002, J CLIMATE, V15, P2301, DOI 10.1175/1520-0442(2002)0152.0.CO;2 KNUTSON TR, 1995, J CLIMATE, V8, P2181, DOI 10.1175/1520-0442(1995)0082.0.CO;2 Knutson TR, 1997, J CLIMATE, V10, P138, DOI 10.1175/1520-0442(1997)0102.0.CO;2 LARGE WG, 1994, REV GEOPHYS, V32, P363, DOI 10.1029/94RG01872 Levitus S., 1998, NOAA ATLAS NESDIS 18, V1, P346 Lin JL, 2007, GEOPHYS RES LETT, V34, DOI 10.1029/2006GL028937 Liu ZY, 2005, J CLIMATE, V18, P4684, DOI 10.1175/JCLI3579.1 Meehl GA, 2001, CLIM DYNAM, V17, P515, DOI 10.1007/PL00007929 MEEHL GA, 1993, CLIM DYNAM, V8, P117 Meehl GA, 2007, B AM METEOROL SOC, V88, P1383, DOI 10.1175/BAMS-88-9-1383 MEEHL GA, 1990, J CLIMATE, V3, P72, DOI 10.1175/1520-0442(1990)0032.0.CO;2 Meehl GA, 2006, CLIM DYNAM, V26, P549, DOI 10.1007/s00382-005-0098-0 MELLOR GL, 1982, REV GEOPHYS, V20, P851, DOI 10.1029/RG020i004p00851 Merryfield WJ, 2006, J CLIMATE, V19, P4009, DOI 10.1175/JCLI3834.1 Moon BK, 2004, GEOPHYS RES LETT, V31, DOI 10.1029/2003GL018829 Moon BK, 2007, CLIM DYNAM, V29, P101, DOI 10.1007/s00382-006-0219-4 Stockdale TN, 1998, J GEOPHYS RES-OCEANS, V103, P14325, DOI 10.1029/97JC02440 Timmermann A, 2002, GEOPHYS RES LETT, V29, DOI 10.1029/2001GL013369 Timmermann A, 1999, NATURE, V398, P694 Trenberth KE, 1997, GEOPHYS RES LETT, V24, P3057, DOI 10.1029/97GL03092 van Oldenborgh GJ, 2005, OCEAN SCI, V1, P81 VECCHI GA, 2008, EXAMINING TROPICAL P, V89 Yang HJ, 2005, GEOPHYS RES LETT, V32, DOI 10.1029/2004GL021624 Yeh SW, 2006, GEOPHYS RES LETT, V33, DOI 10.1029/2005GL025653 Yeh SW, 2007, J CLIMATE, V20, P203, DOI 10.1175/JCLI4001.1 Yeh SW, 2009, NATURE, V461, P511, DOI 10.1038/nature08316 Yukimoto S., 2001, PAP METEOROL GEOPHYS, V51, P47, DOI DOI 10.2467/MRIPAPERS.51.47 ZEBIAK SE, 1987, MON WEATHER REV, V115, P2262, DOI 10.1175/1520-0493(1987)1152.0.CO;2 Zelle H, 2005, J CLIMATE, V18, P4669, DOI 10.1175/JCLI3574.1 Zhang MH, 2006, GEOPHYS RES LETT, V33, DOI 10.1029/2006GL025942 Zhang RH, 2007, GEOPHYS RES LETT, V34, DOI 10.1029/2007GL032119 Zhang RH, 2006, GEOPHYS RES LETT, V33, DOI 10.1029/2005GL025286 Yeh, Sang-Wook Dewitte, Boris Yim, Bo Young Noh, Yign Korea Meteorological Administration Research and Development [RACS_2010-2006]; CNRS (Centre National de la Recherche Scientifique); ANR (Agence Nationale de la Recherche) This work was funded by the Korea Meteorological Administration Research and Development Program under Grant RACS_2010-2006. B. Dewitte benefited from support of the CNRS (Centre National de la Recherche Scientifique) through a STAR (Science and Technology Amicable Research) program and of the ANR (Agence Nationale de la Recherche) through the PCCC (Peru Chile Climate Change) program. 4 SPRINGER NEW YORK CLIM DYNAMThe response of El Nio and Southern Oscillation (ENSO)-like variability to global warming varies comparatively between the two different climate system models, i.e., the Meteorological Research Institute (MRI) and Geophysical Fluid Dynamics Laboratory (GFDL) Coupled General Circulation Models (CGCMs). Here, we examine the role of the simulated upper ocean temperature structure in the different sensitivities of the simulated ENSO variability in the models based on the different level of CO(2) concentrations. In the MRI model, the sea surface temperature (SST) undergoes a rather drastic modification, namely a tendency toward a permanent El Nio-like state. This is associated with an enhanced stratification which results in greater ENSO amplitude for the MRI model. On the other hand, the ENSO simulated by GFDL model is hardly modified although the mean temperature in the near surface layer increases. In order to understand the associated mechanisms we carry out a vertical mode decomposition of the mean equatorial stratification and a simplified heat balance analysis using an intermediate tropical Pacific model tuned from the CGCM outputs. It is found that in the MRI model the increased stratification is associated with an enhancement of the zonal advective feedback and the non-linear advection. In the GFDL model, on the other hand, the thermocline variability and associated anomalous vertical advection are reduced in the eastern equatorial Pacific under global warming, which erodes the thermocline feedback and explains why the ENSO amplitude is reduced in a warmer climate in this model. It is suggested that change in stratification associated with global warming impacts the equatorial wave dynamics in a way that enhances the second baroclinic mode over the gravest one, which leads to the change in feedback processes in the CGCMs. Our results illustrate that the upper ocean vertical structure simulated in the CGCMs is a key parameter of the sensitivity of ENSO-like SST variability to global warming
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