23 research outputs found

    Numerical simulations for performance optimization of a few-cycle terawatt NOPCPA system

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    We present a systematic numerical design and performance study of an ultra-broadband noncollinear optical parametric chirped pulse amplification (NOPCPA) system. Using a split-step Fourier approach, we model a three-stage amplifier system which is designed for the generation of 7 fs pulses with multi-terawatt peak intensity. The numerical results are compared with recent experimental data. Several important aspects and design parameters specific to NOPCPA are identified, and the values of these parameters required to achieve optimal working conditions are investigated. We identify and analyze wavelength-dependent gain saturation effects, which are specific to NOPCPA and have a strong influence on the parametric amplification process. © Springer-Verlag 2007

    Points to consider for the treatment of immune-mediated inflammatory diseases with Janus kinase inhibitors : a systematic literature research

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    Objectives: Review of efficacy and safety of Janus kinase (JAK) inhibition in immune-mediated inflammatory diseases (IMIDs). Methods: A systematic literature research (SLR) of all publications on JAK inhibitors (JAKi) treatment published until March 2019 using MEDLINE, EMBASE and the Cochrane Library. Efficacy and safety were assessed in randomised controlled trials (RCTs), integrating long-term extension periods additionally for safety evaluation. Results: 3454 abstracts were screened with 85 included in the final analysis (efficacy and RCT safety: n=72; safety only: n=13). Efficacy of RCTs investigating tofacitinib (TOFA, n=27), baricitinib (BARI, n=9), upadacitinib (UPA, n=14), filgotinib (FILGO, n=7), decernotinib (DEC, n=3) and peficitinib (PEF, n=7) was evaluated. Six head-to-head trials comparing JAKi with tumour necrosis factor inhibitors (TNFi) were included. Efficacy of JAKi was shown in rheumatoid arthritis (RA) for all agents, psoriatic arthritis (TOFA, FILGO), ankylosing spondylitis (TOFA, FILGO), systemic lupus erythematosus (BARI), chronic plaque psoriasis (TOFA, BARI, PEF), ulcerative colitis (TOFA, UPA), Crohn’s disease (UPA, FILGO) and atopic dermatitis (TOFA, BARI, UPA). Safety analysis of 72 RCTs, one cohort study and 12 articles on long-term extension studies showed increased risks for infections, especially herpes zoster, serious infections and numerically higher rates of venous thromboembolic events. No increased malignancy rates or major adverse cardiac events were observed. Conclusion: JAKi provide good efficacy compared to placebo (and to TNFi in RA and Pso) across various IMIDs with an acceptable safety profile. This SLR informed the task force on points to consider for the treatment of IMIDs with JAKi with the available evidence

    Tracing the influence of the Trans-European Suture Zone into the mantle transition zone

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    Cratons with their thick lithospheric roots can influence the thermal structure, and thus the convective flow, in the surrounding mantle. As mantle temperatures are hard to measure directly, depth variations in the mantle transition zone (MTZ) discontinuities are often employed as a proxy. Here, we use a large new data set of P-receiver functions to map the 410 km and 660 km discontinuities beneath the western edge of the East European Craton and adjacent Phanerozoic Europe across the most fundamental lithospheric boundary in Europe, the Trans-European Suture Zone (TESZ). We observe significantly shorter travel times for conversions from both MTZ discontinuities within the craton, caused by the high velocities of the cratonic root. By contrast, the differential travel time across the MTZ is normal to only slightly raised. This implies that any insulating effect of the cratonic keel does not reach the MTZ. In contrast to earlier observations in Siberia, we do not find any trace of a discontinuity at 520 km depth, which indicates a rather dry MTZ beneath the western edge of the craton. Within most of covered Phanerozoic Europe, the MTZ differential travel time is remarkably uniform and in agreement with standard Earth models. No widespread thermal effects of the various episodes of Caledonian and Variscan subduction that took place during the amalgamation of the continent remain. Only more recent tectonic events, related to Alpine subduction and Quarternary volcanism in the Eifel area, can be traced. While the East European craton shows no distinct imprint into the MTZ, we discover the signature of the TESZ in the MTZ in the form of a linear region of about 350 km width with a 1.5 s increase in differential travel time, which could either be caused by high water content or decreased temperature. Taking into account results of recent S-wave tomographies, raised water content in the MTZ cannot be the main cause for this observation. Accordingly, we explain the increase, equivalent to a 15 km thicker MTZ, by a temperature decrease of about 80 K. We discuss two alternative models for this temperature reduction, either a remnant of subduction or an indication of downwelling due to small-scale, edge-driven convection caused by the contrast in lithospheric thickness across the TESZ. Any subducted lithosphere found in the MTZ at this location is unlikely to be related to Variscan subduction along the TESZ, though, as Eurasia has moved significantly northward since the Variscan orogeny

    Topographic effect in marine magnetotelluric data and implications to the electrical conductivity structure of the mantle beneath the Tristan da Cunha hotspot area

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    Tristan da Cunha Island is one of the hot spots in the Atlantic Ocean. The discussion about its source have not reached consensus yet whether it is in shallow asthenosphere or deeper mantle, because of lack of the geophysical observations in the area. A marine magnetotelluric (MT) experiment was conducted together with seismological observations in the area in 2012–2013 by collaboration between Germany and Japan, in order to give further constraints on the physical state of the mantle beneath the area. A total of 26 seafloor stations were deployed around the Tristan da Cunha islands and available data were retrieved from 23 stations. The MT responses were estimated for those available sites. The detailed data processing will be presented by Chen et al. in this meeting. In this study, we report on the topographic effect on the observed MT responses. During the cruises for seafloor instruments deployment and recovery, detailed bathymetry data were collected around the stations by onboard multi-narrow beam echo sounding (MBES) system. We compiled the MBES data and ETOPO1 data to incorporate the local and regional topography. Then, we applied iterative topographic effect correction and one-dimensional (1-D) conductivity structure inversion. The MT responses of each station were simulated by three-dimensional (3-D) forward modeling. Preliminary results show the overall feature of the observed MT responses at some stations were qualitatively well explained by the seafloor topography included in the conductivity structure model over the 1-D mantle structure. An extreme example is the station near the Tristan da Cunha Island. The impedance phases varies ~300 degrees in shorter period range which is reconstructed by the 3-D forward modeling. Some implications on the lateral variation in the conductivity of the upper mantle will be discussed by demonstrating the residuals between the MT responses corrected for the topographic effect and the 1-D forward response

    Offshore volcanic facies

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    Observation of submarine tectonic activities using long term passive ocean bottom seismometers in the Ross Sea, Antarctica

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    A prominent continental rift is underlying the western part of the Antarctic continent. The current stretching is accompanied by active volcanism at the rim of the Ross Sea as well as underneath the thick ice sheet. Airborne radar measurements have detected active volcanoes south of the Ross Sea. Korea Polar Research Institute (KOPRI) and Alfred Wegener Insitute have deployed 4 long-term broadband Ocean Bottom Seismometers (OBSs) in the Ross Sea near the Jang Bogo Antarctic station during 2011-2012 KOPRI’s Antarctic expedition. It is a pilot research project aiming to better understanding the current seismicity of the West Antarctic Rift System. To accomplish it, we are going to investigate local seismicity and ambient noise around Frankin Island to estimate possible magmatic activity around a seamount. Acoustic noise from glaciers nearby and T-phase propagation study would be conducted in parallel. In addition, we will observe teleseismic events to deteremine the lithospheric structure, and examine shear wave splitting using the OBS data
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