Robert Schaefer
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View article: An h-adaptive collocation method for Physics-Informed Neural Networks
An h-adaptive collocation method for Physics-Informed Neural Networks Open
Despite their flexibility and success in solving partial differential equations, Physics-Informed Neural Networks (PINNs) often suffer from convergence issues, even failing to converge, particularly in problems with steep gradients or loca…
View article: Ground state of the thermosphere and substorm time thermospheric response
Ground state of the thermosphere and substorm time thermospheric response Open
The thermospheric composition (O/N2 ratio and NO) condition represents the state of the thermosphere. Significant changes in thermospheric composition and neutral wind are often observed during non-storm time (e.g. a weak substorm on May 2…
View article: Quality assurance and reporting for FLASH clinical trials:the experience of the FEATHER trial
Quality assurance and reporting for FLASH clinical trials:the experience of the FEATHER trial Open
Research on ultra-high dose rate (UHDR) radiation therapy has indicated its potential to spare normal tissue while maintaining equivalent tumor control compared to conventional treatments. First clinical trials are underway. The randomized…
View article: Dosimetric and biologic intercomparison between electron and proton FLASH beams
Dosimetric and biologic intercomparison between electron and proton FLASH beams Open
Despite major differences in the temporal microstructure of proton and electron beams, this study shows that dosimetric standards can be established. Normal brain protection and tumor control were produced by the two beams. More specifical…
View article: In situ correction of recombination effects in ultra-high dose rate irradiations with protons
In situ correction of recombination effects in ultra-high dose rate irradiations with protons Open
Background. At the Center for Proton Therapy at the Paul Scherrer Institute (PSI) the delivery of proton radiation is controlled via gas-based ionization chambers: the beam is turned off when a certain amount of preset charge has been coll…
View article: Dosimetric and biologic intercomparison between electron and proton FLASH beams
Dosimetric and biologic intercomparison between electron and proton FLASH beams Open
Background and purpose The FLASH effect has been validated in different preclinical experiments with electrons (eFLASH) and protons (pFLASH) operating at a mean dose rate above 40 Gy/s. However, no systematic intercomparison of the FLASH e…
View article: Doppler shifted auroral Lyman-alpha spectra observed by DMSP/SSUSI
Doppler shifted auroral Lyman-alpha spectra observed by DMSP/SSUSI Open
Proton auroras are produced by energetic protons that precipitate, undergo charged exchange, and subsequently emit hydrogen lines before they are ionized again. When viewed from space, the spectral shape of proton auroras is expected to sh…
View article: The role of endogenous opioid neuropeptides in neurostimulation-driven analgesia
The role of endogenous opioid neuropeptides in neurostimulation-driven analgesia Open
Due to the prevalence of chronic pain worldwide, there is an urgent need to improve pain management strategies. While opioid drugs have long been used to treat chronic pain, their use is severely limited by adverse effects and abuse liabil…
View article: How to lighten parametric inverse computations if the misfit is non-convex and the forward solver needs stabilization
How to lighten parametric inverse computations if the misfit is non-convex and the forward solver needs stabilization Open
Solving parametric inverse problems (IPs) for partial differential equations (PDEs) plays an important role in medical diagnosis, resource investigation, nondestructive testing and many other human activities. Real-world IPs formulated as …
View article: Understanding measure-driven algorithms solving irreversibly ill-conditioned problems
Understanding measure-driven algorithms solving irreversibly ill-conditioned problems Open
The paper helps to understand the essence of stochastic population-based searches that solve ill-conditioned global optimization problems. This condition manifests itself by presence of lowlands, i.e., connected subsets of minimizers of po…
View article: Effective Solution of Ill-Posed Inverse Problems with Stabilized Forward Solver
Effective Solution of Ill-Posed Inverse Problems with Stabilized Forward Solver Open
We consider inverse parametric problems for elliptic variational PDEs. They are solved through the minimization of misfit functionals. Main difficulties encountered consist in the misfit multimodality and insensitivity as well as in the we…
View article: Approximation of the objective insensitivity regions using Hierarchic Memetic Strategy coupled with Covariance Matrix Adaptation Evolutionary Strategy
Approximation of the objective insensitivity regions using Hierarchic Memetic Strategy coupled with Covariance Matrix Adaptation Evolutionary Strategy Open
One of the most challenging types of ill-posedness in global optimization is the presence of insensitivity regions in design parameter space, so the identification of their shape will be crucial, if ill-posedness is irrecoverable. Such pro…
View article: Handling insensitivity in multi-physics inverse problems using a complex evolutionary strategy
Handling insensitivity in multi-physics inverse problems using a complex evolutionary strategy Open
In this paper we present a complex strategy for the solution of ill posed, in-verse problems formulated as multiobjective global optimization ones.The strategy is capable of identifying the shape of objective insensitivity regions around c…
View article: Approximating landscape insensitivity regions in solving ill-conditioned inverse problems
Approximating landscape insensitivity regions in solving ill-conditioned inverse problems Open
Solving ill-posed continuous, global optimization problems is challenging. No well-established methods are available to handle the objective intensity that appears when studying the inversion of non-invasive tumor tissue diagnosis or geoph…
View article: MISFIT LANDFORMS IMPOSED BY ILL-CONDITIONED INVERSE PARAMETRIC PROBLEMS
MISFIT LANDFORMS IMPOSED BY ILL-CONDITIONED INVERSE PARAMETRIC PROBLEMS Open
In the paper, we put forward a new topological taxonomy which allows to distinguish and separate multiple solutions to the ill-conditioned parametric inverse problems appearing in engineering, geophysics, medicine, etc. This taxonomy disti…
View article: Resuscitation of <i>Pseudomonas aeruginosa</i> from dormancy requires hibernation promoting factor (PA4463) for ribosome preservation
Resuscitation of <i>Pseudomonas aeruginosa</i> from dormancy requires hibernation promoting factor (PA4463) for ribosome preservation Open
Significance The dormant subpopulations of Pseudomonas aeruginosa biofilms are linked to chronic infections because dormant cells tolerate antibiotic treatment and then repopulate the infections when conditions become favorable. Dormant ce…
View article: Memetic approach for irremediable ill-conditioned parametric inverse problems * *The work presented in this paper has been partially supported by Polish National Science Center grants no. DEC-2015/17/B/ST6/01867 and by the AGH statutory research grant no. 11.11.230.124.
Memetic approach for irremediable ill-conditioned parametric inverse problems * *The work presented in this paper has been partially supported by Polish National Science Center grants no. DEC-2015/17/B/ST6/01867 and by the AGH statutory research grant no. 11.11.230.124. Open
The paper introduces a new taxonomy of ill-posed parametric inverse problems, formulated as global optimization ones. It systematizes irremediable problems, which appear quite often in the real life but cannot be solved using the regulariz…
View article: Modeling Representation of Minorities Under Multiwinner Voting Rules
Modeling Representation of Minorities Under Multiwinner Voting Rules Open
The goal of this paper is twofold. First and foremost, we aim to experimentally and quantitatively show that the choice of a multiwinner voting rule can play a crucial role on the way minorities are represented. We also test the possibilit…
View article: Scalability of Direct Solver for Non-stationary Cahn-Hilliard Simulations with Linearized time Integration Scheme
Scalability of Direct Solver for Non-stationary Cahn-Hilliard Simulations with Linearized time Integration Scheme Open
We study the features of a new mixed integration scheme dedicated to solving the non-stationary variational problems. The scheme is composed of the FEM approximation with respect to the space variable coupled with a 3-leveled time integrat…