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result(s) for
"Becker, Simon"
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Convergence Rates for Quantum Evolution and Entropic Continuity Bounds in Infinite Dimensions
by
Datta, Nilanjana
,
Becker, Simon
in
Banach spaces
,
Boltzmann transport equation
,
Brownian motion
2020
By extending the concept of energy-constrained diamond norms, we obtain continuity bounds on the dynamics of both closed and open quantum systems in infinite dimensions, which are stronger than previously known bounds. We extensively discuss applications of our theory to quantum speed limits, attenuator and amplifier channels, the quantum Boltzmann equation, and quantum Brownian motion. Next, we obtain explicit log-Lipschitz continuity bounds for entropies of infinite-dimensional quantum systems, and classical capacities of infinite-dimensional quantum channels under energy-constraints. These bounds are determined by the high energy spectrum of the underlying Hamiltonian and can be evaluated using Weyl’s law.
Journal Article
Probing plasmonic excitation mechanisms and far-field radiation of single-crystalline gold tapers with electrons
2020
Conical metallic tapers represent an intriguing subclass of metallic nanostructures, as their plasmonic properties show interesting characteristics in strong correlation to their geometrical properties. This is important for possible applications such as in the field of scanning optical microscopy, as favourable plasmonic resonance behaviour can be tailored by optimizing structural parameters like surface roughness or opening angle. Here, we review our recent studies, where single-crystalline gold tapers were investigated experimentally by means of electron energy-loss and cathodoluminescence spectroscopy techniques inside electron microscopes, supported by theoretical finite-difference time-domain calculations. Through the study of tapers with various opening angles, the underlying resonance mechanisms are discussed. This article is part of a discussion meeting issue ‘Dynamic in situ microscopy relating structure and function’.
Journal Article
The EuroCropsML time series benchmark dataset for few-shot crop type classification in Europe
2025
We introduce
EuroCropsML
, an analysis-ready remote sensing dataset based on the open-source
EuroCrops
collection, for
machine learning (ML)
benchmarking of time series crop type classification in Europe. It is the first time-resolved remote sensing dataset designed to benchmark transnational few-shot crop type classification algorithms that supports advancements in algorithmic development and research comparability. It comprises 706683 multi-class labeled data points across 176 crop classes. Each data point features a time series of per-parcel median pixel values extracted from Sentinel-2 L1C data and precise geospatial coordinates.
EuroCropsML
is publicly available on Zenodo.
Journal Article
Fractal analysis of extracellular matrix for observer-independent quantification of intestinal fibrosis in Crohn’s disease
by
Kasajima, Atsuko
,
Friess, Helmut
,
Buck, Annalisa
in
692/308/575
,
692/4020/1503/257
,
692/4020/1503/257/1402
2024
Prevention of intestinal fibrosis remains an unresolved problem in the treatment of Crohn’s disease (CD), as specific antifibrotic therapies are not yet available. Appropriate analysis of fibrosis severity is essential for assessing the therapeutic efficacy of potential antifibrotic drugs. The aim of this study was to develop an observer-independent method to quantify intestinal fibrosis in surgical specimens from patients with CD using structural analysis of the extracellular matrix (ECM). We performed fractal analysis in fibrotic and control histological sections of patients with surgery for CD (n = 28). To specifically assess the structure of the collagen matrix, polarized light microscopy was used. A score to quantify collagen fiber alignment and the color of the polarized light was established. Fractal dimension as a measure for the structural complexity correlated significantly with the histological fibrosis score whereas lacunarity as a measure for the compactness of the ECM showed a negative correlation. Polarized light microscopy to visualize the collagen network underlined the structural changes in the ECM network in advanced fibrosis. In conclusion, observer-independent quantification of the structural complexity of the ECM by fractal analysis is a suitable method to quantify the degree of intestinal fibrosis in histological samples from patients with CD.
Journal Article
Suppression of Th1 differentiation by tryptophan supplementation in vivo
by
Platten, Michael
,
Wick, Wolfgang
,
Mohapatra, Soumya R.
in
Activation
,
Amino acids
,
Analytical Chemistry
2017
Metabolism of the essential amino acid tryptophan (trp) is a key endogenous immunosuppressive pathway restricting inflammatory responses. Tryptophan metabolites promote regulatory T cell (Treg) differentiation and suppress proinflammatory T helper cell (Th)1 and Th17 phenotypes. It has been shown that treatment with natural and synthetic tryptophan metabolites can suppress autoimmune neuroinflammation in preclinical animal models. Here, we tested if oral intake of tryptophan would increase immunosuppressive tryptophan metabolites and ameliorate autoimmune neuroinflammation as a safe approach to treat autoimmune disorders like multiple sclerosis (MS). Without oral supplementation, systemic kynurenine levels decrease during the initiation phase of experimental autoimmune encephalomyelitis (EAE), a mouse model of MS, indicating systemic activation of tryptophan metabolism. Daily oral gavage of up to 10 mg/mouse/day was safe and increased serum kynurenine levels by more than 20-fold for more than 3 h after the gavage. While this treatment resulted in suppression of myelin-specific Th1 responses, there was no relevant impact on clinical disease activity. These data show that oral trp supplementation at subtoxic concentrations suppresses antigen-specific Th1 responses, but suggest that the increase in trp metabolites is not sustained enough to impact neuroinflammation.
Journal Article
Semiclassical Quantization Conditions in Strained Moiré Lattices
by
Wittsten, Jens
,
Becker, Simon
in
Classical and Quantum Gravitation
,
Complex Systems
,
Eigenvalues
2024
In this article we generalize the Bohr–Sommerfeld rule for scalar symbols at a potential well to matrix-valued symbols having eigenvalues that may coalesce precisely at the bottom of the well. As an application, we study the existence of approximately flat bands in moiré heterostructures such as strained two-dimensional honeycomb lattices in a model recently introduced by Timmel and Mele.
Journal Article
Individualized flow-controlled versus conventional pressure-controlled ventilation in on-pump heart surgery (FLOWVENTIN HEARTSURG): study protocol for a randomized controlled trial
by
Geppert, Johannes
,
Kurz, Christian T.
,
Wichelhaus, Lisa-Marie
in
Analysis
,
Biomedicine
,
Cardiac surgery
2023
Background
In on-pump cardiac surgery, lungs are at high risk of periprocedural organ impairment because of atelectasis formation, ventilator-induced lung injury, and hyperinflammation due to the cardiopulmonary bypass which results in postoperative pulmonary complications in half of this patient population. The new ventilation mode flow-controlled ventilation (FCV) uniquely allows full control of ins- and expiratory airway flows. This approach reduces the mechanical power of invasive ventilation as a possible cause of ventilator-induced lung injury. The scope of FLOWVENTIN HEARTSURG is to compare perioperative individualized FCV with best clinical practice pressure-controlled ventilation (PVC) modes in patients with elective on-pump cardiac surgery procedures. We hypothesize that the postoperative inflammatory response can be reduced by the perioperative application of FCV compared to PCV.
Methods
FLOWVENTIN HEARTSURG is a single-center, randomized, parallel-group trial with two intervention arms: perioperative PCV modes (
n
= 70, PCV group) with an individualized positive end-expiratory pressure (PEEP) and a tidal volume of 6–8 ml/kg predicted bodyweight compared to perioperative FCV (
n
= 70, FCV group) with an individualized PEEP and driving pressure, resulting in a liberal tidal volume. As the primary study endpoint interleukin 8 plasma level is assessed 6 h after cardiopulmonary bypass as a surrogate biomarker of systemic and pulmonary inflammation. As secondary aims clinically relevant patient outcomes are analyzed, e.g., perioperative lung function regarding oxygenation indices, postoperative pulmonary and extra-pulmonary complications, SIRS-free days as well as ICU and total inpatient stays. As additional sub-studies with an exploratory approach perioperative right ventricular function parameters are assessed by echocardiography and perioperative lung aeration by electrical impedance tomography.
Discussion
Current paradigms regarding protective low tidal volume ventilation are consciously left in the FCV intervention group in order to reduce mechanical power as a determinant of ventilator-induced lung injury in this high-risk patient population and procedures. This approach will be compared in a randomized controlled trial with current best clinical practice PCV in FLOWVENTIN HEARTSURG.
Trial registration
German Clinical Trials Register
DRKS00018956
. Registered on 12 June 2020 (Version 1), last update on 22 August 2022 (Version 4).
Journal Article
Quantitative assessment of PINN inference on experimental data for gravity currents flows
by
Delcey, Mickaël
,
Cheny, Yoann
,
Becker, Simon
in
Configuration management
,
Engineering Sciences
,
experimental measures
2025
In this paper, we apply physics informed neural networks (PINNs) to infer velocity and pressure field from light attenuation technique (LAT) measurements for gravity current induced by lock-exchange. In a PINN model, physical laws are embedded in the loss function of a neural network, such that the model fits the training data but is also constrained to reduce the residuals of the governing equations. PINNs are able to solve ill-posed inverse problems training on sparse and noisy data, and therefore can be applied to real engineering applications. The noise robustness of PINNs and the model parameters are investigated in a 2 dimensions toy case on a lock-exchange configuration, employing synthetic data. Then we train a PINN with experimental LAT measurements and quantitatively compare the velocity fields inferred to particle image velocimetry measurements performed simultaneously on the same experiment. The results state that accurate and useful quantities can be derived from a PINN model trained on real experimental data which is encouraging for a better description of gravity currents.
Journal Article
Cellular and acellular ex vivo lung perfusion preserve functional lung ultrastructure in a large animal model: a stereological study
2018
Background
Ex vivo lung perfusion (EVLP) is used by an increasing number of transplant centres. It is still controversial whether an acellular or cellular (erythrocyte enriched) perfusate is preferable. The aim of this paper was to evaluate whether acellular (aEVLP) or cellular EVLP (cEVLP) preserves functional lung ultrastructure better and to generate a hypothesis regarding possible underlying mechanisms.
Methods
Lungs of 20 pigs were assigned to 4 groups: control, ischaemia (24 h), aEVLP and cEVLP (both EVLP groups: 24 h ischaemia + 12 h EVLP). After experimental procedures, whole lungs were perfusion fixed, samples for light and electron microscopic stereology were taken, and ventilation, diffusion and perfusion related parameters were estimated.
Results
Lung structure was well preserved in all groups. Lungs had less atelectasis and higher air content after EVLP. No significant group differences were found in alveolar septum composition or blood-air barrier thickness. Small amounts of intraalveolar oedema were detected in both EVLP groups but significantly more in aEVLP than in cEVLP.
Conclusions
Both EVLP protocols supported lungs well for up to 12 h and could largely prevent ischaemia ex vivo reperfusion associated lung injury. In both EVLP groups, oedema volume remained below the level of functional relevance. The group difference in oedema formation was possibly due to inferior septal perfusion in aEVLP.
Journal Article