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Retinal microvascular signs and recurrent vascular events in patients with TIA or minor stroke

Stroke & Vascular Neurology 2023年第5期8卷 379-386,I0001-I0007页

作者： Philipp Klyscz Thomas Ihl Inga Laumeier Maureen Steinicke Matthias Endres Georg Michelson heinrich j.audebert Neurology Charité-Universitätsmedizin BerlinBerlinGermany Center for Stroke Research Berlin Charité-Universitätsmedizin BerlinBerlinGermany Berlin Institute of Health BerlinGermany Excellence Cluster NeuroCure Charité-Universitätsmedizin BerlinBerlinGermany German Center for Neurodegenerative Diseases partner site BerlinGermany German Center for Cardiovascular Research partner site BerlinGermany Ophthalmology Friedrich-Alexander-Universität Erlangen-Nürnberg Medizinische FakultätErlangenGermany Talkingeyes&More GmbH ErlangenGermany

Background and purpose Retinal pathologies are an independent risk factor for ischaemic stroke,but research on the predictive value of retinal abnormalities for recurrent vascular events in patients with prior stroke is *** investigated the association of retinal pathologies with subsequent vascular *** In a substudy of the Intensified secondary prevention intending a reduction of recurrent events in TIA and minor stroke patients(INSPiRE-TMS)trial,we enrolled patients with recent transient ischaemic attack(TIA)or minor stroke with at least one modifiable risk *** outcome was the composite of subsequent vascular *** photographs were taken at baseline and categorised into three different fundus groups by a telemedically linked *** 722 patients participated in the current study and 109 major vascular events *** multivariable adjustments,we did not find a significant association between fundus categories and risk for subsequent vascular events(HRs for moderate vascular retinopathy and vascular retinopathy with vessel rarefaction in comparison to no vascular retinopathy 1.03(95%CI 0.64 to 1.67),p=0.905 and 1.17(95%CI 0.62 to 2.20),p=0.626).In a selective post hoc analysis in patients with diabetes mellitus and hypertension,patients with vascular retinopathy with vessel rarefaction had a higher risk for recurrent stroke(HR 24.14(95%CI 2.74 to 212.50),p=0.004).Conclusions Retinal changes did not predict major subsequent vascular events in patients with recent TIA or minor *** studies are needed to examine the utility of fundus photography in assessing the risk of stroke recurrence in patients with diabetes mellitus and hypertension.

关键词： patients Retinal prevention

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MP-PIC simulation of circulating fluidized beds using an EMMS based drag model for Geldart B particles

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Particuology 2021年第6期19卷 76-90页

作者： Timo Dymala Tom Wytrwat Stefan heinrich Hamburg University of Technology Institute of Solids Process Engineering and Particle TechnologyDenickestr.1521073 HamburgGermany

In this study the multiphase particle-in-cell(MP-PIC)method is used for the simulation of two pilot-scale circulating fluidized beds(CFBs)with quartz sand belonging to Geldart’s group B as bed *** simulations were performed using a homogeneous drag model as well as a structure dependent drag model based on the energy minimization multi-scale method(EMMS).The results are compared with experimental data from literature as well as *** simulations with the EMMS based drag model show a good agreement of the time-averaged axial solids concentration,circulation rate and riser pressure ***,a lower grid sensitivity is observed compared to the homogeneous drag *** contrast to the conventional drag model a dense bottom zone is predicted by the EMMS based drag *** overprediction of the solid concentration in the dense bottom zone is presumably due to an overprediction of the cluster diameter that is calculated using an empirical cluster diameter *** shows the necessity for a new meso-scale cluster correlation for the simulation of Geldart B ***,the results of the time-averaged radial solids concentration differ from the expectations of a core-annulus flow indicating that a mesh refinement at the walls is ***,the importance of using a realistic particle size distribution is identified.

关键词： 3D-CFD simulation Circulating fluidized bed(CFB) Multiphase particle-in-cell method(MP-PIC) Energy minimizing multi-scale theory(EMMS) Validation study

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Pathological tumor response to neoadjuvant therapy in borderline resectable pancreatic cancer

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Hepatobiliary & Pancreatic Diseases International 2019年第4期18卷 305-306页

作者： Stefan heinrich General Visceral and Transplantation Surgery University Hospital of Mainz

Surgery is the standard therapy for pancreatic ductal adenocarcinoma(PDAC).After the dramatic decline of operative mortality over the past decades,the indications for pancreas resections have been continuously extended:currently resections of the portal/superior mesenteric vein are considered standard by many centers,and even arterial resections are under *** these changes,different expert groups have defined resectability criteria containing a grey zone(“borderline resectable disease”)of tumors,which may be technically resectable with appropriate surgical expertise,but resection inherits an increased risk of an R1-resection[1].

关键词： Surgery mortality operative

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Influence of liquid layers on energy absorption during particle impact

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Particuology 2009年第4期7卷 245-259页

作者： Sergiy Antonyuk Stefan heinrich Niels Deen Hans Kuipers Hamburg University of Technology Institute of Solids Process Engineering and Particle Technology Denickestr. 15 21071 Hamburg Germany University of Twente Fundamentals of Chemical Reaction Engineering Faculty of Science and Technology PO Box 217 Enschede 7500 AE The Netherlands

The influence of the thickness of a covering liquid layer and its viscosity as well as the impact velocity on energy loss during the normal impact on a flat steel wall of spherical granules with a liquid layer was studied. Free-fall experiments were performed to obtain the restitution coefficient of elastic-plastic γ- Al2O3 granules by impact on the liquid layer, using aqueous solutions of hydroxypropyl methylcellulose with different concentrations for variation of viscosity （1-300 mPa s）, In the presence of a liquid layer, increase of liquid viscosity decreases the restitution coefficient and the minimum thickness of the liquid layer at which the granule sticks to the wall. The measured restitution coefficients were compared with experiments performed without liquid layer. In contrast to the dry restitution coefficient, due to viscous losses at lower impact velocity, higher energy dissipation was obtained, A rational explanation for the effects obtained was given by results of numerically solved force and energy balances for a granule impact on a liquid layer on the wall. The model takes into account forces acting on the granule including viscous, surface tension, capillary, contact, drag, buoyancy and gravitational forces. Good agreement between simulations and experiments has been achieved.

关键词： Granule impact Restitution coefficient Energy dissipation Liquid layer Liquid bridge

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Transit time ultrasound perivascular flow probe technology is superior to MR imaging on hepatic blood flow measurement in a porcine model

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Hepatobiliary & Pancreatic Diseases International 2018年第6期17卷 538-545页

作者： Mohamed Bekheit Chloe audebert Petru Bucur Hans Adriaensen Emilie Bled Mylène Wartenberg Irene Vignon-Clementel Eric Vibert Inserm Unité 1193 112 Boulevard Paul Valliant CuturierVillejuifFrance Institute of medical sciences University of AberdeenAberdeenUK Centre de recherche Inria de Paris ParisFrance Sorbonne Universités UPMC University of Paris 6Laboratoire Jacques-LouisLionsParisFrance CHRU hopitaux de ToursChirurgie Héato-biliaire et pancréatiqueTransplantation HéatiqueToursFrance Plateforme Chirurgie et Imagerie pour le Recherche et l’Enseignement(CIRE) ImagerieUMR-PRC37380 NouzillyCentre INRA Val de LoireFrance AP-HP Hoital Paul BrousseCentre Héato-BiliaireVillejuifFrance

Background: The hepatic hemodynamics is an essential parameter in surgical planning as well as in various disease processes. The transit time ultrasound(TTUS) perivascular flow probe technology is widely used in clinical practice to evaluate the hepatic inflow, yet invasive. The phase-contrast-MRI(PC-MRI) is not invasive and potentially applicable in assessing the hepatic blood flow. In the present study, we compared the hepatic inflow rates using the PC-MRI and the TTUS probe, and evaluated their predictive value of post-hepatectomy adverse events. Methods: Eighteen large white pigs were anaesthetized for PC-MRI and approximately 75% hepatic resection was performed under a unified protocol. The blood flow was measured in the hepatic artery(Qha), the portal vein(Qpv), and the aorta above the celiac trunk(Qca) using PC-MRI, and was compared to the TTUS probe. The Bland-Altman method was conducted and a partial least squares regression(PLS) model was implemented. Results: The mean Qpv measured in PC-MRI was 0.55 ± 0.12 L/min, and in the TTUS probe was 0.74 ± 0.17 L/min. Qca was 1.40 ± 0.47 L/min in the PC-MRI and 2.00 ± 0.60 L/min in the TTUS probe. Qha was 0.17 ± 0.10 L/min in the PC-MRI, and 0.13 ± 0.06 L/min in the TTUS probe. The Bland-Altman method revealed that the estimated bias of Qca in the PC-MRI was 32%(95% CI:-49% to 15%); Qha 17%(95% CI:-15% to 51%); and Qpv 40%(95% CI:-62% to 18%). The TTUS probe had a higher weight in predicting adverse outcomes after 75% resection compared to the PC-MRI( β= 0.35 and 0.43 vs β = 0.22 and 0.07, for tissue changes and premature death, respectively). Conclusions: There is a tendency of the PC-MRI to underestimate the flow measured by the TTUS probes. The TTUS probe measures are more predictive of relevant post-hepatectomy outcomes.

关键词： Hepatic blood flow Phase contrast MRI Transit time ultrasound probe Porcine model Liver surgery

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The ultimate goal of modeling—Simulation of system and plant performance

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Particuology 2011年第4期9卷 320-329页

作者： joachim Werther Stefan heinrich Maksym Dosta Ernst-Ulrich Hartge Institute of Solids Process Engineering and Particle Technology Hamburg University of Technology

Modern production processes in chemical, pharmaceutical and biological industries are characterized by complex process structures, which consist of different apparatuses and process steps. Modeling the entire process requires simulating all units altogether, while taking into account interconnections between them, Nevertheless, in the area of solids processing, there is nowadays an unfilled gap from the side of computer support of process modeling in allowing effective optimization and prediction of the behavior of the whole plant, This paper presents a tool for flowsheet simulation which allows the simulation of the stationary behavior of complex processes dealing with solids and its extension towards dynamic modeling, Also, a new simulation concept is proposed on the basis of the multiscale approach. On the macroscale, fiowsheet simulation is performed with the help of the SolidSim system. Parameters for the macromodels in Solid-Sim are predicted by microscale simulation. The models for the two scales are then coupled by inter-scale communication laws. Application of the proposed modeling concept is shown by an example of fluidized bed granulation.

关键词： Flowsheet simulation Multiscale modeling Plant performance Solids processes Granulation

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Product design based on discrete particle modeling of a fluidized bed granulator

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Particuology 2014年第1期12卷 13-24页

作者： Lennart Fries Sergiy Antonyuk Stefan heinrich Gerhard Niederreiter Stefan Palzer Nestlé Research Center Institute of Solids Process Engineering and Particle Technology Hamburg University of Technology

Fluidized bed agglomeration is a process commonly used to construct powdered food or pharmaceuti cal products to improve their instant properties. This works analyzes the influence of a wide range of operating parameters （i.e., fluidization air flow rate, temperature, and liquid injection rate） on growth rate, process stability, and product particle structure. Different granulator configurations （i.e., top spray, Wurster coater, spouted bed） are compared using identical process parameters. The impacts of both pro cess variables and granulator geometry on the fluidization regime, the particle and collision dynamics, and the resulting product structure and corresponding properties are studied in detailed simulations using a discrete particle model （DPM） and labscale agglomeration experiments with amorphous dextrose syrup （DE21）. The combination of numerical and experimental results allows to correlate the kinetics of micro scale particle interactions and the final product properties （i.e., agglomerate structure and strength）. In conclusion, detailed DPM simulations are proven as a valuable tool for knowledgebased product design.

关键词： FluidizationAgglomerationDiscrete element methodFood powderCollision dynamics

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Simulation of spray coating in a spouted bed using recurrence CFD

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Particuology 2019年第1期17卷 92-103页

作者： Paul Kieckhefena Thomas Lichtenegger Swantje Pietsch Stefan Pirker Stefan heinrich Institute of Solids Process Engineering and Particle Technology Hamburg University of Technology. HamburgGermany Department for Particulate Flow Modelling. johannes Kepler University LinzAustria Linz Institute of Technology (LIT) Johannes Kepler UniversityLinzAustria

Although numerical models such as the computational fluid dynamics–discrete element method (CFD–DEM) have enabled the accurate simulation of laboratory-scale apparatuses, the application of these methods to large-scale apparatuses with many particles and time scales ranging from minutes to hours remains a challenge. The recently developed recurrence CFD (rCFD) method seeks to overcome these issues in pseudo-periodic processes by extrapolating globally recurring patterns in a physically meaningful way and describing the transport and interaction of passive scalars using Lagrangian tracers. Spouted beds represent an interesting target because of the associated variety of flow regimes. They can be effectively described by CFD–DEM on the time scale of tens of seconds, whereas industrially relevant processes typically take hours. In this contribution, we established the validity of applying the Lagrangian rCFD method to spouted beds by demonstrating the accurate reproduction of the particle residence time distribution in a fictitious spray zone. The deposition of spray droplets onto tracer particles was simulated for 1 h, and the particle surface coverage distribution was estimated using a statistical approach for both an unstabilized prismatic spouted bed and one stabilized by draft plates.

关键词： CFD–DEM Recurrence CFD Spray coating Time-scale decoupling Spouted bed Draft plate

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Coefficient of restitution for particles impacting on wet surfaces： An improved experimental approach

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Particuology 2016年第2期14卷 1-9页

作者： B. Cunger V. Salikov S. heinrich S. Antonyuk V.S. Sutkar N.G. Deen j.A.M. Kuipers Institute of Solids Process Engineering and Particle Technology Hamburg University of Technology Denickestrasse 15 21073 Hamburg Germany Particle Process Engineering Department of Mechanical and Process Engineering University ofKaiserslautern Cottlieb-Daimler-Strasse 67663 Kaiserslautern Germany Multiphase Reactors Group Department of Chemical Engineering and Chemistry Eindhoven University of Technology P.O. Box 513 5600 MB EindhovenThe Netherlands

The coefficient of restitution is widely used to characterize the energy dissipation rate in numerical simulations involving particle collisions. The challenge in measuring the coefficient of restitution is the strong scatter seen in experimental data that results from varying particle properties, i.e. shape and surface roughness, and from imperfections in the experimental technique. To minimize this scattering, a novel experimental setup was developed based on two synchronized high-speed cameras capturing the collision behaviour of a particle in three dimensions. To measure the wet restitution coefficient, which describes particle impact in the presence of a liquid layer in the contact region, additional accuracy can be achieved by measuring the liquid layer thickness by a high-precision optical confocal sensor. The coefficient of restitution was measured for glass particles with two different diameters, at different relative velocities and liquid layer thicknesses, with a focus on small collision velocities and thin liquid layers, using both the improved （three dimensional） and the conventional （two dimensional） approaches to quantify the improvement of the new method＇s accuracy.

关键词： Particle impact Coefficient of restitution Liquid layer Improved experimental setup

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A Reinforcement Learning approach for the continuous electricity market ofGermany: Trading from the perspective of a wind park operator

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Energy and AI 2022年第2期8卷 67-78页

作者： Malte Lehna Björn Hoppmann Christoph Scholz Renéheinrich Fraunhofer Institute for Energy Economics and Energy System Technology(IEE) Königstor 5934119 KasselGermany

With the rising extension of renewable energies, the intraday electricity markets have recorded a growingpopularity amongst traders as well as electric utilities to cope with the induced volatility of the energysupply. Through their short trading horizon and continuous nature, the intraday markets offer the abilityto adjust trading decisions from the day-ahead market or reduce trading risk in a short-term notice. Producersof renewable energies utilize the intraday market to lower their forecast risk, by modifying their providedcapacities based on current forecasts. However, the market dynamics are complex due to the fact that thepower grids have to remain stable and electricity is only partly storable. Consequently, robust and intelligenttrading strategies are required that are capable to operate in the intraday market. In this work, we proposea novel autonomous trading approach based on Deep Reinforcement Learning (DRL) algorithms as a possiblesolution. For this purpose, we model the intraday trade as a Markov Decision Process (MDP) and employ theProximal Policy Optimization (PPO) algorithm as our DRL approach. A simulation framework is introducedthat enables the trading of the continuous intraday price in a resolution of one minute steps. We test ourframework in a case study from the perspective of a wind park operator. We include next to general tradeinformation both price and wind forecasts. On a test scenario of German intraday trading results from 2018,we are able to outperform multiple baselines with at least 45.24% improvement, showing the advantage of theDRL algorithm. However, we also discuss limitations and enhancements of the DRL agent, in order to increasethe performance in future works.

关键词： Deep Reinforcement Learning German intraday electricity trading Deep neural networks Markov Decision Process Proximal Policy Optimization Electricity price forecast

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