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Search Results: 1 - 10 of 5060 matches for " Christoph Schweiger "
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Evaluation of a new arterial pressure-based cardiac output device requiring no external calibration
Christopher Prasser, Sylvia Bele, Cornelius Keyl, Stefan Schweiger, Benedikt Trabold, Matthias Amann, Julia Welnhofer, Christoph Wiesenack
BMC Anesthesiology , 2007, DOI: 10.1186/1471-2253-7-9
Abstract: We studied 20 critically ill patients, aged 16 to 74 years (mean, 55.5 ± 18.8 years), who required both arterial and pulmonary artery pressure monitoring. COPAC measurements were performed at least every 4 hours and calculated as the average of 3 measurements, while COAP values were taken immediately at the end of bolus determinations. Accuracy of measurements was assessed by calculating the bias and limits of agreement using the method described by Bland and Altman.A total of 164 coupled measurements were obtained. Absolute values of COPAC ranged from 2.80 to 10.80 l/min (mean 5.93 ± 1.55 l/min). The bias and limits of agreement between COPAC and COAP for unequal numbers of replicates was 0.02 ± 2.92 l/min. The percentage error between COPAC and COAP was 49.3%. The bias between percentage changes in COPAC (ΔCOPAC) and percentage changes in COAP (ΔCOAP) for consecutive measurements was -0.70% ± 32.28%. COPAC and COAP showed a Pearson correlation coefficient of 0.58 (p < 0.01), while the correlation coefficient between ΔCOPAC and ΔCOAP was 0.46 (p < 0.01).Although the COAP algorithm shows a minimal bias with COPAC over a wide range of values in an inhomogeneous group of critically ill patients, the scattering of the data remains relative wide. Therefore, the used algorithm (V 1.03) failed to demonstrate an acceptable accuracy in comparison to the clinical standard of cardiac output determination.Accurate evaluation of cardiac performance is an important goal in the treatment of critically ill patients. Usually a pulmonary artery catheter (PAC) is placed for assessment of cardiac output (CO), but as a result of the current discussion about the usefulness and risks of the PAC [1,2], several less invasive techniques have been discussed as alternatives to the intermittent bolus thermodilution cardiac output (COPAC) measurement by the PAC [3], which still represents the clinical standard.Particularly techniques using arterial waveform analysis for CO assessment (PiCCOplus
Quantification of the internalization patterns of superparamagnetic iron oxide nanoparticles with opposite charge
Christoph Schweiger, Raimo Hartmann, Feng Zhang, Wolfgang J. Parak, Thomas H. Kissel, Pilar Rivera_Gil
Journal of Nanobiotechnology , 2012, DOI: 10.1186/1477-3155-10-28
Abstract: The physicochemical characterization of the nanoparticles showed particles of approximately the same size and shape as well as similar magnetic properties, only differing in charge due to different surface coatings. Incubation of the cells with both nanoparticles resulted in strong differences in the internalization rate and in the intracellular localization depending on the charge. Quantitative and qualitative analysis of nanoparticles-organelle colocalization experiments revealed that positively charged particles were found to enter the cells faster using different endocytotic pathways than their negative counterparts. Nevertheless, both nanoparticles species were finally enriched inside lysosomal structures and their efficiency in agarose phantom relaxometry experiments was very similar.This quantitative analysis demonstrates that charge is a key factor influencing the nanoparticle-cell interactions, specially their intracellular accumulation. Despite differences in their physicochemical properties and intracellular distribution, the efficiencies of both nanoparticles as MRI agents were not significantly different.
GPU-Accelerated Finite Element Method for Modelling Light Transport in Diffuse Optical Tomography
Martin Schweiger
International Journal of Biomedical Imaging , 2011, DOI: 10.1155/2011/403892
Abstract: We introduce a GPU-accelerated finite element forward solver for the computation of light transport in scattering media. The forward model is the computationally most expensive component of iterative methods for image reconstruction in diffuse optical tomography, and performance optimisation of the forward solver is therefore crucial for improving the efficiency of the solution of the inverse problem. The GPU forward solver uses a CUDA implementation that evaluates on the graphics hardware the sparse linear system arising in the finite element formulation of the diffusion equation. We present solutions for both time-domain and frequency-domain problems. A comparison with a CPU-based implementation shows significant performance gains of the graphics accelerated solution, with improvements of approximately a factor of 10 for double-precision computations, and factors beyond 20 for single-precision computations. The gains are also shown to be dependent on the mesh complexity, where the largest gains are achieved for high mesh resolutions. 1. Introduction Diffuse optical tomography (DOT) is a functional imaging modality for medical applications that has the potential to provide three-dimensional images of the scattering and absorption parameter distributions in vivo, from which clinically relevant physiological parameters such as tissue and blood oxygenation states and state changes can be derived. Applications include brain activation visualisation [1, 2], brain oxygenation monitoring in infants [3], and breast tumour detection [4]. Data acquisition systems consist of an infrared light delivery system that illuminates the tissue surface at different locations, and detectors that measure the transmitted light at a set of surface positions. Measurements can be performed in continuous wave (CW) mode, in time-resolved mode using ultra-short input pulses and time-resolved detectors, or in frequency-domain mode, using modulated light sources and measuring the phase shift and modulation amplitude at the detector locations. Due to the high level of scattering in most biological tissues, image reconstruction in DOT is an ill-posed nonlinear problem whose solution generally requires the formulation of a forward model of light propagation in inhomogeneous scattering tissue. Frequently utilised light transport models include stochastic models such as Monte-Carlo simulation [5], or deterministic models such as the radiative transfer equation (RTE) [6] or the diffusion equation (DE) [7]. Numerical solution approaches include finite difference, finite element, finite
Zur brasilianischen Textart "Memorial Acadêmico": wie man sich in Brasilien auf eine akademische Stelle bewirbt
Schweiger, Kathrin;
Pandaemonium Germanicum , 2009, DOI: 10.1590/S1982-88372009000100006
Abstract: this paper analyses the brazilian genre "memorial acadêmico" and its function, outlining similarities and differences in comparison with the german genre "akademischer lebenslauf. based on a corpus of seven "memoriais", differences in terms of proposition and illocution between these two genres were identified.
Anerkennung und Arbeitslosigkeit
Gottfried Schweiger
Meta : Research in Hermeneutics, Phenomenology and Practical Philosophy , 2011,
Abstract: This paper aims to explore the case of unemployment from the perspective of recognition theory as it was conceived by Axel Honneth. In the first part I present a shortened form of recognition theory and afterwards, in the second part, its take on work and labor in modern societies. Finally, the third part elaborates how unemployment can be understood and evaluated from this viewpoint. I argue that unemployment itself is not a form of misrecognition and therefore not moral evil. But what has to be criticized are the negative effects of unemployment and the degrading treatment of unemployed people.
Silja Schoett: Medienbiografie und Familie – Jugendliche erz hlen. Theorie und Methode der medienbiografischen Fallrekonstruktion. Hamburg u.a.: LIT Verlag 2009.
Hannes Schweiger
querelles-net , 2010,
Abstract: Die Familie bestimmt in hohem Ma e, welche Medien Kinder und Jugendliche in welcher Lebensphase wie und warum rezipieren. Silja Schoett beweist diese nicht neue Annahme auf überzeugende Art anhand ihrer Analyse zweier Fallgeschichten mit Hilfe des Instruments einer medienbiografischen Fallrekonstruktion. Sie begründet diese Methode ausführlich und macht sie auf andere Beispiele und Fragestellungen übertragbar. Aufgrund ihrer systemischen Perspektive betrachtet sie das Individuum im famili ren Gesamtzusammenhang, blendet dabei aber andere Faktoren (u. a. soziales Umfeld, Schule, konomische Verh ltnisse) aus, die die Lebensgeschichte und die mediale Sozialisation ebenfalls mitbestimmen. To a great extent, the family determines what media children and youth consume, as well as in what phase of life, how, and why. Silja Schoett proves this not-so-new claim in a convincing manner by analyzing two case studies utilizing as her instrument a media-biographical case reconstruction. She justifies these methods extensively and thus makes them applicable to other examples and problems. On the basis of her systematic perspective, she examines the individual within the entire familial context, ignoring however other factors (for example social environment, school, economic relations), which equally determine life stories and media socialization.
Beyond Growth & Jobs? Perspectives for the EU Single Market Policy Framework
Christian Schweiger
Journal of Contemporary European Research , 2009,
Abstract: This article provides a critical analysis of the scope and the internal dynamics of the EU-27 Single European Market (SEM) policy framework, which is characterised by the intrinsic tension between application of hard deregulatory strategy in the area of market liberalisation and the soft approach of the Open Method of Co-ordination (OMC). The latter acknowledges the diversity of national socio-economic models and reluctance of member states to transfer key areas of economic and social policy-making to the EU level. It instead concentrates on promoting best practice on the basis of policy exchange and learning and the overall framework targets set out in the Lisbon Strategy. The lack of commitment amongst member states towards applying the OMC and the Lisbon targets as a basis for national policy development illustrates that the Commission has yet to achieve a consensus amongst the EU-27 member states on common economic and social policy priorities. In the wake of the global economic crisis the SEM policy agenda therefore risks being reduced to a market liberalisation programme with waning levels of support from citizens and national administrations.
Exclusive Photon-Induced Hadronic Reactions at Large Momentum Transfers
W. Schweiger
Physics , 1995,
Abstract: It is generally assumed that due to factorization of long- and short-distance dynamics perturbative QCD can be applied to exclusive hadronic reactions at large momentum transfers. Within such a perturbative approach diquarks turn out to be a useful phenomenological device to model non-perturbative effects still observable in the kinematic range accessible by present-days experiments. The basic ingredients of the perturbative formalism with diquarks, i.e. Feynman rules for diquarks and quark-diquark wave functions of baryons, are briefly summarized. Applications of the diquark model to the electromagnetic form factors of the proton in the space- as well as time-like region, Compton-scattering off protons, gamma-gamma -> p-pbar, and photoproduction of Kaons are discussed.
The interplay of soft and hard contributions in the electromagnetic pion form factor
W. Schweiger
Physics , 2001, DOI: 10.1016/S0920-5632(02)01336-1
Abstract: We consider various relativistic models for the valence Fock-state wave function of the pion. These models are obtained from simple instant-form wave functions by applying a Melosh rotation to the spin part and by imposing physical constraints on the parameters. We discuss how the soft and the hard (perturbative) parts of the electromagnetic form factor are affected by the choice of the model and by the Melosh rotation.
Differentiable equivalence of fractional linear maps
Fritz Schweiger
Mathematics , 2006, DOI: 10.1214/074921706000000257
Abstract: A Moebius system is an ergodic fibred system $(B,T)$ (see \citer5) defined on an interval $B=[a,b]$ with partition $(J_k),k\in I,#I\geq 2$ such that $Tx=\frac{c_k+d_kx}{a_k+b_kx}$, $x\in J_k$ and $T|_{J_k}$ is a bijective map from $J_k$ onto $B$. It is well known that for $#I=2$ the invariant density can be written in the form $h(x)=\int_{B^*}\frac{dy}{(1+xy)^2}$ where $B^*$ is a suitable interval. This result does not hold for $#I\geq 3$. However, in this paper for $#I=3$ two classes of interval maps are determined which allow the extension of the before mentioned result.
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