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Sökning: WFRF:(Zahn Andreas)

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1.
  • Hagendorff, Andreas, et al. (författare)
  • Manual on indications and performance of echocardiography-Update 2020 of the German Cardiac Society
  • 2020
  • Ingår i: KARDIOLOGE. - : SPRINGER HEIDELBERG. - 1864-9718 .- 1864-9726. ; 14:5, s. 396-431
  • Tidskriftsartikel (refereegranskat)abstract
    • The new manual on indications for and performance of echocardiography focuses primarily on the transthoracic echocardiographic approach. The performance of a standardized documentation in transthoracic echocardiography includes the acquisition of several cineloops and Doppler spectra with consecutive measurements illustrated by figures and a scheme of an echocardiographic report. The extended documentation in transthoracic echocardiography is presented with respect to specific pathological alterations of the heart. This includes alterations of the left ventricular wall thickness, the global and regional reduction of left ventricular function, diastolic dysfunction with normal left ventricular systolic function, pressure and volume overload of the right ventricle and the reduction of right ventricular function and pathological alterations of the heart valves. Echocardiography performed in the presence of aortic valve stenosis and regurgitation, mitral valve stenosis and regurgitation, tricuspid valve regurgitation as well as less common heart valve diseases and endocarditis is presented in special sections. The manual ends with sections describing additional echocardiographic modalities, the reporting and the use of emergency echocardiography.
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2.
  • Hagendorff, Andreas, et al. (författare)
  • Manual zur Indikation und Durchführung spezieller echokardiographischer Anwendungen
  • 2021
  • Ingår i: Der Kardiologe. - : Springer Nature. - 1864-9718 .- 1864-9726. ; 15:6, s. 595-641
  • Tidskriftsartikel (refereegranskat)abstract
    • The second manual on indications for and performance of echocardiography focusses on specific echocardiographic modalities and special problems in several patient cohorts. Practical aspects are discussed with priority. Established echocardiographic modalities are transesophageal, stress and contrast echocardiography. Modern technologies, such as 3D echocardiography and deformation imaging play an important role in nearly all scenarios of clinical echocardiography. This complete echocardiographic spectrum is incorporated into emergency and intensive care medicine, monitoring interventions of structural heart diseases, cardiac surgery, patients with cardiac assist devices, adult patients with congenital heart diseases and the care of highly infectious patients in pandemics. The diagnostic procedures of conventional and modern echocardiography are highlighted in this manual. The use of 3D echocardiography to characterize cardiac morphology and the application of deformation imaging to objectify cardiac function are already established in clinical practice. Stress echocardiography to detect myocardial ischemia and viability or to diagnose valvular heart diseases, assessment of coronary flow reserve to analyze myocardial perfusion and contrast echocardiography for left ventricular opacification and tumor characterization are increasingly being used to improve diagnostics. As mentioned for conventional echocardiography in the last manual of echocardiography in 2009, the modern features in echocardiography require standardized documentation and acquisition of certain images with optimized ultrasound settings, because conclusive and reproducible data analysis can only be performed if the image quality is sufficient.
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3.
  • Hermann, Markus, et al. (författare)
  • An optical particle size spectrometer for aircraft-borne measurements in IAGOS-CARIBIC
  • 2016
  • Ingår i: Atmospheric Measurement Techniques. - : Copernicus GmbH. - 1867-1381 .- 1867-8548. ; 9:5, s. 2179-2194
  • Tidskriftsartikel (refereegranskat)abstract
    • The particle number size distribution is an important parameter to characterize the atmospheric aerosol and its influence on the Earth's climate. Here we describe a new optical particle size spectrometer (OPSS) for measurements of the accumulation mode particle number size distribution in the tropopause region on board a passenger aircraft (IAGOS-CARIBIC observatory: In-service Aircraft for a Global Observing System - Civil Aircraft for Regular Investigation of the Atmosphere Based on an Instrument Container). A modified KS93 particle sensor from RION Co., Ltd., together with a new airflow system and a dedicated data acquisition system, is the key component of the CARIBIC OPSS. The instrument records individual particle pulse signal curves in the particle size range 130-1110 nm diameter (for a particle refractive index of 1.47-i0.006) together with a time stamp and thus allows the post-flight choice of the time resolution and the size distribution bin width. The CARIBIC OPSS has a 50 % particle detection diameter of 152 nm and a maximum asymptotic counting efficiency of 98 %. The instrument's measurement performance shows no pressure dependency and no particle coincidence for free tropospheric conditions. The size response function of the CARIBIC OPSS was obtained by a polystyrene latex calibration in combination with model calculations. Particle number size distributions measured with the new OPSS in the lowermost stratosphere agreed within a factor of 2 in concentration with balloon-borne measurements over western North America. Since June 2010 the CARIBIC OPSS is deployed once per month in the IAGOS-CARIBIC observatory.
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4.
  • Slemr, Franz, et al. (författare)
  • Atmospheric mercury measurements onboard the CARIBIC passenger aircraft
  • 2016
  • Ingår i: Atmospheric Measurement Techniques. - : Copernicus GmbH. - 1867-1381 .- 1867-8548. ; 9:5, s. 2291-2302
  • Tidskriftsartikel (refereegranskat)abstract
    • Goal of the project CARIBIC (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrumented Container) is to carry out regular and detailed observations of atmospheric composition (particles and gases) at cruising altitudes of passenger aircraft, i.e. at 9-12km. Mercury has been measured since May 2005 by a modified Tekran instrument (Tekran Model 2537 A analyser, Tekran Inc., Toronto, Canada) during monthly intercontinental flights between Europe and South and North America, Africa, and Asia. Here we describe the instrument modifications, the post-flight processing of the raw instrument signal, and the fractionation experiments.
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5.
  • Slemr, Franz, et al. (författare)
  • Mercury distribution in the upper troposphere and lowermost stratosphere according to measurements by the IAGOS-CARIBIC observatory : 2014-2016
  • 2018
  • Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 18:16, s. 12329-12343
  • Tidskriftsartikel (refereegranskat)abstract
    • Mercury was measured onboard the IAGOS-CARIBIC passenger aircraft from May 2005 until February 2016 during near monthly sequences of mostly four intercontinental flights from Germany to destinations in North and South America, Africa and South and East Asia. Most of these mercury data were obtained using an internal default signal integration procedure of the Tekran instrument but since April 2014 more precise and accurate data were obtained using post-flight manual integration of the instrument raw signal. In this paper we use the latter data. Increased upper tropospheric total mercury (TM) concentrations due to large scale biomass burning were observed in the upper troposphere (UT) at the equator and southern latitudes during the flights to Latin America and South Africa in boreal autumn (SON) and boreal winter (DJF). TM concentrations in the lowermost stratosphere (LMS) decrease with altitude above the thermal tropopause but the gradient is less steep than reported before. Seasonal variation of the vertical TM distribution in the UT and LMS is similar to that of other trace gases with surface sources and stratospheric sinks. Speciation experiments suggest comparable TM and gaseous elementary mercury (GEM) concentrations at and below the tropopause leaving little space for Hg2+ (TM-thinsp;GEM) being the dominating component of TM here. In the stratosphere significant GEM concentrations were found to exist up to 4 km altitude above the thermal tropopause. Correlations with N2O as a reference tracer suggest stratospheric lifetimes of 72±37 and 74±27 years for TM and GEM, respectively, comparable to the stratospheric lifetime of COS. This coincidence, combined with pieces of evidence from us and other researchers, corroborates the hypothesis that Hg2+ formed by oxidation in the stratosphere attaches to sulfate particles formed mainly by oxidation of COS and is removed with them from the stratosphere by air mass exchange, gravitational sedimentation and cloud scavenging processes.
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6.
  • Andersson, Sandra, et al. (författare)
  • Significant radiative impact of volcanic aerosol in the lowermost stratosphere.
  • 2015
  • Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 6
  • Tidskriftsartikel (refereegranskat)abstract
    • Despite their potential to slow global warming, until recently, the radiative forcing associated with volcanic aerosols in the lowermost stratosphere (LMS) had not been considered. Here we study volcanic aerosol changes in the stratosphere using lidar measurements from the NASA CALIPSO satellite and aircraft measurements from the IAGOS-CARIBIC observatory. Between 2008 and 2012 volcanism frequently affected the Northern Hemisphere stratosphere aerosol loadings, whereas the Southern Hemisphere generally had loadings close to background conditions. We show that half of the global stratospheric aerosol optical depth following the Kasatochi, Sarychev and Nabro eruptions is attributable to LMS aerosol. On average, 30% of the global stratospheric aerosol optical depth originated in the LMS during the period 2008-2011. On the basis of the two independent, high-resolution measurement methods, we show that the LMS makes an important contribution to the overall volcanic forcing.
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7.
  • Dahlin, Andreas, 1980, et al. (författare)
  • Nanoplasmonic sensing of metal-halide complex formation and the electric double layer capacitor
  • 2012
  • Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3372 .- 2040-3364. ; 4:7, s. 2339-2351
  • Tidskriftsartikel (refereegranskat)abstract
    • Many nanotechnological devices are based on implementing electrochemistry with plasmonic nanostructures, but these systems are challenging to understand. We present a detailed study of the influence of electrochemical potentials on plasmon resonances, in the absence of surface coatings and redox active molecules, by synchronized voltammetry and spectroscopy. The experiments are performed on gold nanodisks and nanohole arrays in thin gold films, which are fabricated by improved methods. New insights are provided by high resolution spectroscopy and variable scan rates. Furthermore, we introduce new analytical models in order to understand the spectral changes quantitatively. In contrast to most previous literature, we find that the plasmonic signal is caused almost entirely by the formation of ionic complexes on the metal surface, most likely gold chloride in this study. The refractometric sensing effect from the ions in the electric double layer can be fully neglected, and the charging of the metal gives a surprisingly small effect for these systems. Our conclusions are consistent for both localized nanoparticle plasmons and propagating surface plasmons. We consider the results in this work especially important in the context of combined electrochemical and optical sensors.
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8.
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9.
  • Friberg, Johan, et al. (författare)
  • Sources of increase in lowermost stratospheric sulphurous and carbonaceous aerosol background concentrations during 1999-2008 derived from CARIBIC flights
  • 2014
  • Ingår i: Tellus. Series B: Chemical and Physical Meteorology. - : Stockholm University Press. - 0280-6509 .- 1600-0889.
  • Tidskriftsartikel (refereegranskat)abstract
    • This study focuses on sulphurous and carbonaceous aerosol, the major constituents of particulate matter in the lowermost stratosphere (LMS), based on in situ measurements from 1999 to 2008. Aerosol particles in the size range of 0.082 mm were collected monthly during intercontinental flights with the CARIBIC passenger aircraft, presenting the first long-term study on carbonaceous aerosol in the LMS. Elemental concentrations were derived via subsequent laboratory-based ion beam analysis. The stoichiometry indicates that the sulphurous fraction is sulphate, while an O/C ratio of 0.2 indicates that the carbonaceous aerosol is organic. The concentration of the carbonaceous component corresponded on average to approximately 25% of that of the sulphurous, and could not be explained by forest fires or biomass burning, since the average mass ratio of Fe to K was 16 times higher than typical ratios in effluents from biomass burning. The data reveal increasing concentrations of particulate sulphur and carbon with a doubling of particulate sulphur from 1999 to 2008 in the northern hemisphere LMS. Periods of elevated concentrations of particulate sulphur in the LMS are linked to downward transport of aerosol from higher altitudes, using ozone as a tracer for stratospheric air. Tropical volcanic eruptions penetrating the tropical tropopause are identified as the likely cause of the particulate sulphur and carbon increase in the LMS, where entrainment of lower tropospheric air into volcanic jets and plumes could be the cause of the carbon increase.
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10.
  • Martinsson, Bengt G., et al. (författare)
  • Formation and composition of the UTLS aerosol
  • 2019
  • Ingår i: npj Climate and Atmospheric Science. - : Springer Science and Business Media LLC. - 2397-3722. ; 2:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Stratospheric aerosol has long been seen as a pure mixture of sulfuric acid and water. Recent measurements, however, found a considerable carbonaceous fraction extending at least 8 km into the stratosphere. This fraction affects the aerosol optical depth (AOD) and the radiative properties, and hence the radiative forcing and climate impact of the stratospheric aerosol. Here we present an investigation based on a decade (2005–2014) of airborne aerosol sampling at 9–12 km altitude in the tropics and the northern hemisphere (NH) aboard the IAGOS-CARIBIC passenger aircraft. We find that the chemical composition of tropospheric aerosol in the tropics differs markedly from that at NH midlatitudes, and, that the carbonaceous stratospheric aerosol is oxygen-poor compared to the tropospheric aerosol. Furthermore, the carbonaceous and sulfurous components of the aerosol in the lowermost stratosphere (LMS) show strong increases in concentration connected with springtime subsidence from overlying stratospheric layers. The LMS concentrations significantly exceed those in the troposphere, thus clearly indicating a stratospheric production of not only the well-established sulfurous aerosol, but also a considerable but less understood carbonaceous component.
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