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Spectrally tunable high-power Yb:fiber chirped-pulse amplifier

Photonics Research 2022年第10期10卷 2309-2316页

作者： VALENTINA SHUmAKOVA VITO F.PECILE JAKOB FELLINGER mICHAEL LESKOWSCHEK P.E.COLLIN ALDIA ALINE S.mAYER LUKAS W.PERNER SARPER SALmAN mINGQI FAN PRANNAY BALLA STÉPHANE SCHILT christoph m.heyl INGmAR HARTL GIL PORAT OLIVER H.HECKL Christian Doppler Laboratory for mid-IR Spectroscopy and Semiconductor Optics Faculty Center for Nano Structure ResearchFaculty of PhysicsUniversity of ViennaA-1090 ViennaAustria Photonics Institute TU WienA-1040 ViennaAustria Vienna Doctoral School in Physics University of ViennaA-1090 ViennaAustria Deutsches Elektronen-Synchrotron DESY 22607 HamburgGermany Laboratoire Temps-Fréquence Universitéde NeuchâtelCH-2000 NeuchâtelSwitzerland GSI Helmholtzzentrum für Schwerionenforschung GmbH 64291 DarmstadtGermany Helmholtz-Institute Jena 07743 JenaGermany Department of Electrical and Computer Engineering University of AlbertaEdmontonAlberta T6G 1H9Canada Department of Physics University of AlbertaEdmontonAlberta T6G 2E1Canada

Tailoring the properties of the driving laser to the need of applications often requires compromises among laser stability,high peak and average power levels,pulse duration,and spectral *** instance,spectroscopy with optical frequency combs in the extreme/visible ultraviolet spectral region requires a high peak power of the near-IR driving laser,and therefore high average power,pulse duration of a few tens of fs,and maximal available spectral ***,the parametric conversion efficiency is higher for pulses with a duration in the 100-fs range due to temporal walk-off and coating *** we suggest an approach to adjust the spectral characteristics of high-power chirped-pulse amplification(CPA)to the requirements of different nonlinear frequency converters while preserving the low-phase-noise(PN)properties of the *** achieve spectral tunability,we installed a mechanical spectral shaper in a free-space section of the stretcher of an in-house-developed ytterbium-fiber-based CPA *** CPA system delivers 100 W of average power at a repetition rate of 132.4 *** gaining control over the spectral properties,we preserve the relative-intensity-noise and PN properties of the *** high-power CPA can easily be adjusted to deliver either a spectrum ideal for mid-IR light generation(full width at half maximum of∼11 nm,compressed pulse duration of 230 fs)or a spectrum ideal for highly nonlinear processes such as high-harmonic generation(−10 dB level of>50 nm,transform-limited pulse duration of∼65 fs).

关键词： pulse power fiber

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Factor 30 Pulse Compression by Hybrid multipass multiplate Spectral Broadening

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Ultrafast Science 2022年第1期2卷 17-26页

作者： marcus Seidel Prannay Balla Chen Li Gunnar Arisholm Lutz Winkelmann Ingmar Hartl christoph m.heyl Deutsches Eilektronen Synchrotron DESY Notkestrasse 8522607 HamburgGermany Helmholtz Institute Jena Frobelstieg 307743 JenaGermany GSI Helmholtzzentrum fir Schwerionenforschung GmbH Planckstrasse 164291 DarmstadtGermany FFI(Norwegian Defence Research Estabishment) P.O.Box 25NO 2027 KjellerNorway

As ultrafast laser technology advances towards ever higher peak and average powers,generating sub-50 fs pulses from laser architectures that exhibit best power-scaling capabilities remains a major ***,we present a very compact and highly robust method to compress 1.24 ps pulses to 39fs by means of only a single spectral broadening stage which neither requires vacuum parts nor custom-made *** approach is based on the hybridization of the multiplate continuum *** multipass cell spectral broadening *** combination leads to significantly higher spectral broadening factors in bulk material than what has been reported from either method ***,our approach efficiently suppresses adverse features of single-pass bulk spectral *** use a burst-mode Yb:YAG laser emitting pulses with 80 mW peak power that are enhanced to more than 1 GW after *** only 0.19%rms pulse-to-pulse energy fluctuations,the technique exhibits excellent ***,we have measured state-of-the-art spectral-spatial homogeneity and good beam quality of m^(2)=1.2 up to a spectral broadening factor of *** to the method's simplicity,compactness,and scalability,it is highly attractive for turning a picosecond laser into an ultrafast light source that generates pulses of only a few tens of femtoseconds duration.

关键词： attractive simplicity Pulse

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Influence of rolling friction on single spout fluidized bed simulation

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Particuology 2012年第5期10卷 582-591页

作者： christoph Goniva christoph Kloss Niels G. Deen Johannes A.m.Kuipers Stefan Pirker Christian-Doppler Laboratory on Particulate Flow modelling Johannes Kepler UniversityLinz Austria DCS Computing GmbH Linz Austria Christian-Doppler Laboratory on Particulate Flow modelling Johannes Kepler UniversityLinz Austria Department of Chemical Engineering and Chemistry Eindhoven University of TechnologyEindhovenThe Netherlands Department of Chemical Engineering and Chemistry Eindhoven University of TechnologyEindhovenThe Netherlands Christian-Doppler Laboratory on Particulate Flow modelling Johannes Kepler UniversityLinzAustria Institute of Fluid mechanics and Heat Transfer Johannes Kepler UniversityLinzAustria

In this paper we study the effect of rolling friction on the dynamics in a single spout fluidized bed using Discrete Element method （DEm） coupled to Computational Fluid Dynamics （CFD）. In a first step we neglect rolling friction and show that the results delivered by the open source CFD-DEm framework applied in this study agree with previous simulations documented in literature. In a second step we include a rolling friction sub-model in order to investigate the effect of particle non-sphericity. The influence of particle-particle as well as particle-wall rolling friction on the flow in single spout fluidized bed is studied separately. Adequate rolling friction model parameters are obtained using first principle DEm simulations and data from literature. Finally, we demonstrate the importance of correct modelling of rolling friction for coupled CFD-DEm simulations of spout fluidized beds. We show that simulation results can be improved significantly when applying a rolling friction model, and that experimental data from literature obtained with Positron Emission Particle Trackin~ fPEPT） technique can be satisfactorily reoroduced.

关键词： CFD-DEmOpen sourceRolling frictionSpout fluidized bedNon-sphericity

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Towards a better understanding of antimicrobial resistance dissemination:what can be learnt from studying model conjugative plasmids?

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military medical Research 2022年第5期9卷 592-602页

作者： Zhen Shen christoph m.Tang Guang-Yu Liu Sir William Dunn School of Pathology University of OxfordOxfordOX13REUK Department of Laboratory medicine Ren Ji HospitalSchool of MedicineShanghai Jiao Tong UniversityShanghai200127China

Bacteria can evolve rapidly by acquiring new traits such as virulence,metabolic properties,and most importantly,antimicrobial resistance,through horizontal gene transfer(HGT).multidrug resistance in bacteria,especially in Gram-negative organisms,has become a global public health threat often through the spread of mobile genetic *** represents a major form of HGT and involves the transfer of DNA from a donor bacterium to a recipient by direct *** plasmids,a major vehicle for the dissemination of antimicrobial resistance,are selfish elements capable of mediating their own transmission through *** spread to and survive in a new bacterial host,conjugative plasmids have evolved mechanisms to circumvent both host defense systems and compete with co-resident *** mechanisms have mostly been studied in model plasmids such as the F plasmid,rather than in conjugative plasmids that confer antimicrobial resistance(AmR)in important human pathogens.A better understanding of these mechanisms is crucial for predicting the flow of antimicrobial resistance-conferring conjugative plasmids among bacterial populations and guiding the rational design of strategies to halt the spread of antimicrobial ***,we review mechanisms employed by conjugative plasmids that promote their transmission and establishment in Gram-negative bacteria,by following the life cycle of conjugative plasmids.

关键词： Horizontal gene transfer Antimicrobial resistance Conjugative plasmids Type IV secretion system Restriction-modification systems SOS response Entry exclusion Fertility inhibition

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Neural correlates of the Heidelberg music Therapy: indicators for the regeneration of auditory cortex in tinnitus patients?

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Neural Regeneration Research 2015年第9期10卷 1373-1375页

作者： christoph m.Krick Heike Argstatter Department of Neuroradiology Saarland University Hospital German Center for music Therapy Research (Viktor Dulger Institute) DZm

Tinnitus, the phenomenon of ringing or buzzing in the ears without an external sound source is one of the most commonly reported symptoms in otorhinolaryngology and affects 10 - 15% of the general population. models have been developed to account for neural basis of tinnitus, its pathogenesis and its consequences on mental health （deRidder et al., 2013）. In most cases tinnitus onset follows a partial hearing impairment. Peripheral sensory deprivation due to cochlear damages may prompt increased neuronal activity in the central auditory system in order to adapt the neural sensitivity to the reduced sensory inputs. This central gain could over amplify the ＂neural noise＂ and thus trigger a homeostatic down-regulation of inhib- itory synapses in the auditory cortical map leading to specific reorganization of the cortical representation of the tinnitus percept. Dysfunctional feedback connections from limbic regions to auditory brain areas, interacting at the thalamic level, may account for the psychological impairment.

关键词： indicators for the regeneration of auditory cortex in tinnitus patients Neural correlates of the Heidelberg music Therapy PTC

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A note on circle packing

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Journal of Zhejiang University-Science C(Computers and Electronics) 2012年第8期13卷 559-564页

作者： Young Joon AHN christoph m. HOFFmANN Paul ROSEN Department of mathematics Education Chosun University Gwangju 501-759 Korea Department of Computer Science Purdue University West Lafayette IN 47907 USA Scientific Computing and Imaging Institute University of Utah Salt Lake City UT 84112 USA

The problem of packing circles into a domain of prescribed topology is considered. The circles need not have equal radii. The Collins-Stephenson algorithm computes such a circle packing. This algorithm is parmlelized in two different ways and its performance is reported for a triangular, planar domain test case. The implementation uses the highly parallel graphics processing unit （GPU） on commodity hardware. The speedups so achieved are discussed based on a number of experiments.

关键词： Circle packing Algorithm performance Parallel computation Graphics processing unit (GPU)

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Effect of orchard age on soil nitrogen transformation in subtropical China and implications

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Journal of Environmental Sciences 2015年第8期27卷 10-19页

作者： Yushu Zhang Jinbo Zhang Tongbin Zhu christoph müller Zucong Cai School of Geography Sciences Nanjing Normal University Institute of Soil and Fertilizer Fujian Academy of Agricultural Sciences Jiangsu Provincial Key Laboratory of materials Cycling and Pollution Control Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application Key Laboratory of Virtual Geographical Environment Ministry of Education Nanjing Normal University Department of Plant Ecology Justus-Liebig University Giessen

A better understanding of nitrogen transformation in soils could reveal the capacity for biological inorganic N supply and improve the efficiency of N fertilizers. In this study, a15 N tracing study was carried out to investigate the effects of converting woodland to orchard, and orchard age on the gross rates of N transformation occurring simultaneously in subtropical soils in Eastern China. The results showed that inorganic N supply rate was remained constant with soil organic C and N contents increased after converting woodland into citrus orchard and with increasing orchard age. This phenomenon was most probably due to the increase in the turnover time of recalcitrant organic-N, which increased with decreasing soil p H along with increasing orchard age significantly. The amo A gene copy numbers of both archaeal and bacterial were stimulated by orchard planting and increased with increasing orchard age. The nitrification capacity（defined as the ratio of gross rate of nitrification to total gross rate of mineralization） increased following the michaelis–menten equation, sharply in the first 10 years after woodland conversion to orchard, and increased continuously but much more slowly till 30 years. Due to the increase in nitrification capacity and unchanged NO3-consumption, the dominance of ammonium in inorganic N in woodland soil was shifted to nitrate dominance in orchard soils. These results indicated that the risk of NO3-loss was expected to increase and the amount of N needed from fertilizers for fruit growth did not change although soil organic N accumulated with orchard age.

关键词： 15N tracing technique Gross rates of nitrogen transformation Subtropical orchard soil

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Effect of wall rougheners on cross-sectional flow characteristics for non-spherical particles in a horizontal rotating cylinder

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Particuology 2014年第1期12卷 44-53页

作者： Guang Lu James R.Third christoph R.müller ETH Zürich Department of Mechanical and Process Engineering Institute of Energy Technology Laboratory of Energy Science and Engineering8092 Zürich Switzerland

Discrete-element-method （DEm） simulations have been performed to investigate the cross-sectional flow of non-spherical particles in horizontal rotating cylinders with and without wall rougheners. The non-spherical particles were modeled using the three-dimensional super-quadric equation. The influence of wall rougheners on flow behavior of grains was studied for increasing particle blockiness. moreover, for approximately cubic particles （squareness parameters [555]）, the rotational speed, gravitational acceleration and particle size were altered to investigate the effect of wall rougheners under a range of operating conditions. For spherical and near-spherical particles （approximately up to the squareness parameters [344]）, wall rougheners are necessary to prevent slippage of the bed against the cylinder wall. For highly cubic particle geometries （squareness parameters larger than [3441）, wall rougheners resulted in a counter-intuitive decrease in the angle of repose of the bed. In addition, wall rougheners employed in this study were demonstrated to have a higher impact on bed dynamics at higher rotational speeds and lower gravitational accelerations. Nevertheless, using wall rougheners had a comparatively small influence on particle-flow characteristics for a bed composed of finer grains.

关键词： Granular flowNon-spherical particlesRotating cylinderDiscrete element method (DEm)Kiln

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Second-generation direct-acting-antiviral hepatitis C virus treatment: Efficacy, safety, and predictors of SVR12

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World Journal of Gastroenterology 2016年第35期22卷 8050-8059页

作者： christoph R Werner Julia m Schwarz Daniel P Egetemeyr Robert Beck Nisar P malek Ulrich m Lauer christoph P Berg Department of Gastroenterology Hepatology and Infectiology University Hospital Tübingen Institute of medical Virology University Hospital Tübingen

AIm To gather data on the antiviral efficacy and safety of second generation direct acting antiviral(DAA) treatment with respect to sustained virological response(SVR) 12 wk after conclusion of treatment, and to determine predictors of SVR12 in this *** Two hundred and sixty patients treated with SOF combination partners PR(n = 51), R(n = 10), SmV(n = 30), DCV(n = 81), LDV(n = 73), or 3D(n = 15).144/260 were pre-treated, 89/260 had liver cirrhosis, 56/260 had portal hypertension with platelets mELD score ≥ 10 and 17/260 were postliver transplantation patients. 194/260 had HCV GT1, 44/260 HCV *** Two hundred and forty/256(93.7%) patients achieved SVR12(m ITT); 4/260 were lost to follow-up. SVR12 rates for subgroups were: 92% for SOF/DCV, 93% for each SOF/SmV, SOF/PR, 94% for SOF/LDV, 100% for 3D, 94% for pretreated, 87% for liver cirrhosis, 82% for patients with platelets m relapse, 6 prematurely discontinued treatment, of which 4 died. Negative predictors of SVR12 were a platelet count mELD score ≥ 10(P ment GT3 had significantly lower SVR rates than GT1(P = 0.016). Side effects were mild. CONCLUSION Excellent SVR12 rates and the favorable side-effect profile of DAA-combination therapy can be well translated into "real-world". Patients with advanced liver disease, signs of portal hypertension, especially with platelets me comparatively higher rates of virological failure.

关键词： Sofosbuvir Simeprevir Ledipasvir Hepatitis C Liver transplant Sustained virological response Liver cirrhosis Side effects Resistance Daclatasvir

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Surface roughness of zirconia for full-contour crowns after clinically simulated grinding and polishing

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International Journal of Oral Science 2014年第4期6卷 241-246页

作者： Rim Hmaidouch Wolf-Dieter mller Hans-christoph Lauer Paul Weigl Department of Prosthodontics and Geriatric Dentistry Faculty of Oral and Dental Medicine at Johann Wolfgang Goethe-University Department of Prosthodontics and Geriatric Dentistry University of Medicine Charite Department of Postgraduate Education Faculty of Oral and Dental Medicine at Johann Wolfgang Goethe-University

The aim of this study was to evaluate the effect of controlled intraoral grinding and polishing on the roughness of full-contour zirconia compared to classical veneered zirconia. Thirty bar-shaped zirconia specimens were fabricated and divided into two groups（n515）. Fifteen specimens（group 1） were glazed and 15 specimens（group 2） were veneered with feldspathic ceramic and then glazed. Prior to grinding,maximum roughness depth（Rmax） values were measured using a profilometer, 5 times per specimen. Simulated clinical grinding and polishing were performed on the specimens under water coolant for 15 s and 2 N pressure. For grinding, NTI diamonds burs with grain sizes of 20 mm, 10 mm, and 7.5 mm were used sequentially. The ground surfaces were polished using NTI kits with coarse, medium and fine polishers. After each step, Rmaxvalues were determined. Differences between groups were examined using one-way analysis of variance（ANOVA）. The roughness of group 1 was significantly lower than that of group 2. The roughness increased significantly after coarse grinding in both groups. The results after glazing were similar to those obtained after fine grinding for non-veneered zirconia. However, fine-ground veneered zirconia had significantly higher roughness than venerred, glazed zirconia. No significant difference was found between fine-polished and glazed zirconia, but after the fine polishing of veneered zirconia, the roughness was significantly higher than after *** can be concluded that for full-contour zirconia, fewer defects and lower roughness values resulted after grinding and polishing compared to veneered zirconia. After polishing zirconia, lower roughness values were achieved compared to glazing; more interesting was that the grinding of glazed zirconia using the NTI three-step system could deliver smooth surfaces comparable to untreated glazed zirconia surfaces.

关键词： full-contour zirconia grinding polishing roughness veneering porcelain

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