A5029120895- Characterization and Applications of Magnetic Nanoparticles
- Electrical and Bioimpedance Tomography
- Advanced MRI Techniques and Applications
- Geomagnetism and Paleomagnetism Studies
- Sparse and Compressive Sensing Techniques
- Medical Imaging Techniques and Applications
- Spectroscopy and Quantum Chemical Studies
- Laser-Matter Interactions and Applications
- Atomic and Subatomic Physics Research
- Neural Networks and Applications
- Optical Polarization and Ellipsometry
- Minerals Flotation and Separation Techniques
- Digital Filter Design and Implementation
- Augmented Reality Applications
- Numerical Methods and Algorithms
- 3D Shape Modeling and Analysis
- Advanced Neuroimaging Techniques and Applications
- Radiomics and Machine Learning in Medical Imaging
- Porphyrin and Phthalocyanine Chemistry
- Advanced X-ray and CT Imaging
- Optical Network Technologies
- Mass Spectrometry Techniques and Applications
- NMR spectroscopy and applications
- Image and Signal Denoising Methods
- Computer Graphics and Visualization Techniques
University Medical Center Hamburg-Eppendorf
2019-2023
Universität Hamburg
2014-2023
Hamburg University of Technology
2019-2023
University Medical Center
2021
Max Planck Institute for the Structure and Dynamics of Matter
2014
Hamburg Centre for Ultrafast Imaging
2014
National Institute of Standards and Technology
1991
University of Freiburg
1991
We report here the first experimental study of femtosecond time-resolved molecular multiphoton ionization. Femtosecond pump-probe techniques are combined with time-of-flight spectroscopy to measure transient ionization spectra ${\mathrm{Na}}_{2}$ in a molecular-beam experiment. The wave-packet motions different potentials show that incoherent contributions from direct photoionization singly excited state and excitation autoionization bound doubly determine observed signal.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTFemtosecond time-resolved wave packet motion in molecular multiphoton ionization and fragmentationT. Baumert, B. Buehler, M. Grosser, R. Thalweiser, V. Weiss, E. Wiedenmann, G. GerberCite this: J. Phys. Chem. 1991, 95, 21, 8103–8110Publication Date (Print):October 1, 1991Publication History Published online1 May 2002Published inissue 1 October 1991https://pubs.acs.org/doi/10.1021/j100174a019https://doi.org/10.1021/j100174a019research-articleACS...
Purpose The aim of this work is to develop a high‐performance, flexible, and easy‐to‐use MRI reconstruction framework using the scientific programming language Julia. Methods Julia modern, general purpose with strong features in area signal/image processing numerical computing. It has high‐level syntax but still generates efficient machine code that usually as fast comparable C/C++ applications. In addition itself, sophisticated package management system makes proper modularization...
Image reconstruction plays an important role for the tomographic imaging technique magnetic particle (MPI) since measured raw data cannot be directly interpreted. Instead, one needs to invert image formation process, which involves solution of ill-conditioned linear system equations. Currently, most MPI researchers have implemented custom algorithms that compared source code is not openly available. The software package MPIReco.jl aims change this situation by providing a reference...
In Magnetic Particle Imaging (MPI), the system matrix plays an important role, as it encodes relationship between particle concentration and measured signal. Its acquisition requires a time-consuming calibration scan, whereas its size leads to high memory-demand. Both of these aspects can be limiting factors in practice. order reduce measurement time, compressed sensing exploits knowledge that MPI has sparse representation suitably chosen domain. this work we demonstrate rows allow low-rank...
Background signals are a primary source of artifacts in magnetic particle imaging and limit the sensitivity method since background often not precisely known vary over time. The state-of-the art for handling uses one or several calibration measurements with an empty scanner bore subtracts linear combination these from actual measurement. This approach yields satisfying results case that taken close proximity to measurement when signal drifts linearly. In this work, we propose joint...
We investigate the imaging of electron wave-packet dynamics by measuring pattern inelastically scattered photons. For this purpose, we develop a theory time-resolved Compton scattering. demonstrate that, using sufficiently short x-ray pulse, scattering cross section directly reflects instantaneous momentum density electron. Therefore, propose as tool to image in space. To illustrate this, simulate wave packets argon time-dependent configuration-interaction singles method. Specifically,...
We study the relaxation dynamics of photoexcited Fe-II complexes dissolved in water and identify pathway which molecular complex follows presence a hydration shell bound at interface between solvent. Starting from low-spin state, can reach high-spin state via cascade different possible transitions involving electronic as well vibrational processes. By numerically exact path integral calculations for relaxational continuous solvent model, we find that life times intermittent states are order...
In magnetic particle imaging, the time consuming measurement of a system matrix is required before image reconstruction.Reduction can be achieved with help compressed sensing, which based on sparsity systemmatrix in suitable transform domain. this work, we propose regularization functions to exploit additional correlations multi-patch matrices. Experiments show that resulting recovery method allows successful at higherundersampling factors than standard sensing recovery. Int. J. Mag. Part....
Magnetic particle imaging (MPI) data is commonly reconstructed using a system matrix acquired in time-consuming calibration measurement. The approach has the important advantage over model-based reconstruction that it takes complex physics as well imperfections into account. This benefit comes for cost needs to be re-calibrated whenever scan parameters, types or even environment (e.g. viscosity temperature) changes. One route reducing time sampling of at subset spatial positions intended...
Background signals are a primary source of artifacts in magnetic particle imaging and limit the sensitivity method since background often not precisely known vary over time. The state-of-the art for handling uses one or several calibration measurements with an empty scanner bore subtracts linear combination these from actual measurement. This approach yields satisfying results case that taken close proximity to measurement when signal drifts linearly. In this work, we propose joint...
The non-equidistant fast Fourier transform (NFFT) is an extension of the famous (FFT), which can be applied to non-equidistantly sampled data in time/space or frequency domain. It approximative algorithm that allows control approximation error such a way machine precision reached while keeping algorithmic complexity same order as regular FFT. NFFT plays major role many signal processing applications and has been intensively studied from theoretical computational perspective. fastest CPU...
Zielsetzung Ziel dieser Studie war es, Fettquantifizierung erstmals für die detektorbasierte Dual-layer Spektral-CT (dlsCT), > 120 kV automatisiert spektrale Informationen generiert, zu entwickeln und Ergebnisse mittels MRT evaluieren.
This work proposes an efficient way to adapt MRI sampling patterns a given anatomy and imaging context using small set of representative training data. Such techniques were shown help shorten experiments while guaranteeing high image quality. An often encountered drawback such methods are computation times. We extend the recently proposed OEDIPUS framework by making use Bayesian Fisher information matrix. Based on latter we devise algorithm, which can be more than order magnitude faster for...
Magnetic Particle Imaging is a highly sensitive tracer-based imaging method able to image as little nanogram of tracer material. In practice, background signals stemming from imperfections in the scanner instrumentation make it challenging achieve these very high sensitivities. case where signal static over time can be simply subtracted using an empty reference measurement. this work we develop that capable handling dynamic signals. Since particle and are superimposed, propose perform joint...
Purpose: The aim of this work is to develop a high-performance, flexible and easy-to-use MRI reconstruction framework using the scientific programming language Julia. Methods: Julia modern, general purpose with strong features in area signal / image processing numerical computing. It has high-level syntax but still generates efficient machine code that usually as fast comparable C/C++ applications. In addition itself, sophisticated package management system makes proper modularization...