29 results on '"Christopher Pohl"'
Search Results
2. In-vitro analysis of resorption processes following high hydrostatic pressure treatment of human trabecular bone
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Janine Waletzko-Hellwig, Christopher Pohl, Henrike Loeffler, Michael Dau, Michael Schlosser, Rainer Bader, and Annett Klinder
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High hydrostatic pressure ,Allograft processing ,Bone resorption ,In-vitro study ,Materials of engineering and construction. Mechanics of materials ,TA401-492 - Abstract
The present study focused on the investigation of the resorption behavior of high hydrostatic pressure (HHP) treated bone allografts in vitro by analyzing the differentiation and activity of osteoclast precursors. HHP is known to be an efficient method for devitalization of bone grafts and a gentle alternative compared to conventional processing. While bone resorption is part of the physiological fracture healing, highly processed allografts are prone to excessive degradation, which ultimately leads to graft failure. The influence of HHP treatment on the extent of resorption was analyzed in bone blocks cultivated with peripheral blood mononuclear cells (PBMCs). Data on gene and protein expression as well as histological alterations were obtained. The present study showed that an application of 500 MPa led to significant osteoclastic differentiation and activity which was observed already after 8 h of incubation. Whereas a treatment of 250 MPa resulted also in the differentiation of PBMCs, osteoclastic activity was similar to the untreated control. Thus, the pressure level of HHP is crucial for the extent of degradation processes. Based on our results a treatment with 500 MPa might not be suitable for allografts intended for subsequent clinical applications. This study provides a basis for further experiments including in vivo studies which should focus on the equilibrium of bone formation and bone resorption.
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- 2023
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3. Effect of High Hydrostatic Pressure on Human Trabecular Bone Regarding Cell Death and Matrix Integrity
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Janine Waletzko-Hellwig, Christopher Pohl, Janik Riese, Michael Schlosser, Michael Dau, Nadja Engel, Armin Springer, and Rainer Bader
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high hydrostatic pressure ,bone replacement material ,allograft ,gel electophoresis ,histology ,cell dealth ,Biotechnology ,TP248.13-248.65 - Abstract
The reconstruction of critical size bone defects is still clinically challenging. Even though the transplantation of autologous bone is used as gold standard, this therapy is accompanied by donor site morbidities as well as tissue limitations. The alternatively used allografts, which are devitalized due to thermal, chemical or physical processing, often lose their matrix integrity and have diminished biomechanical properties. High Hydrostatic Pressure (HHP) may represent a gentle alternative to already existing methods since HHP treated human osteoblasts undergo cell death and HHP treated bone cylinders maintain their mechanical properties. The aim of this study was to determine the biological effects caused by HHP treatment regarding protein/matrix integrity and type of cell death in trabecular bone cylinders. Therefore, different pressure protocols (250 and 300 MPa for 10, 20 and 30 min) and end point analysis such as quantification of DNA-fragmentation, gene expression, SDS-PAGE, FESEM analysis and histological staining were performed. While both protein and matrix integrity was preserved, molecular biological methods showed an apoptotic differentiation of cell death for lower pressures and shorter applications (250 MPa for 10 and 20 min) and necrotic differentiation for higher pressures and longer applications (300 MPa for 30 min). This study serves as a basis for further investigation as it shows that HHP successfully devitalizes trabecular bone cylinders.
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- 2021
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4. vMAGIC—Automatic Code Generation for VHDL
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Christopher Pohl, Carlos Paiz, and Mario Porrmann
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Computer engineering. Computer hardware ,TK7885-7895 - Published
- 2009
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5. Immune complexes-mediated activation of neutrophils in systemic lupus erythematosus is dependent on RNA recognition by toll-like receptor 8
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Ting Wang, Runa Kuley, Payton Hermanson, Peirou Chu, Christopher Pohlmeyer, Jayamary Divya Ravichandar, David Lopez, Gundula Min-Oo, Natasha Crellin, Ching Shang, and Christian Lood
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immune complexes ,neutrophils ,systemic lupus erythematosus ,toll-like receptor 8 ,RNA recognition ,Immunologic diseases. Allergy ,RC581-607 - Abstract
IntroductionNeutrophil activation is important in systemic lupus erythematosus (SLE). We previously demonstrated that ribonucleoprotein (RNP) immune complexes (ICs) promoted neutrophil activation in a TLR7/8-dependent manner. However, it remains unclear if this mechanism occurs in patients. Here, we investigated the role of RNA recognition by evaluating TLR7/8 in plasma-mediated neutrophil activation in SLE.MethodsPlasma levels of neutrophil activation markers and ICs were measured by ELISA and flow cytometry in SLE patients (n=151) and healthy controls (HCs, n=31). Neutrophils were incubated with plasma and assessed for CD66b and CD11b up-regulation by flow cytometry in the presence of select inhibitors to define the mechanisms of neutrophil activation by SLE plasma.ResultsSLE plasma induced higher levels of CD66b (p=0.0002) and CD11b (p=0.01) expression than plasma from HCs. Blocking FcγRIIA, targeting RNA sensing by adding RNase, or blocking TLR7/8, TLR8 only, or IRAK4, decreased plasma-mediated neutrophil activation (p
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- 2024
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6. Tall tower observations of a northward surging gust front in central Amazon and its role in the mesoscale transport of carbon dioxide
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Luciane I. Reis, Maurício I. Oliveira, Cléo Q. Dias‐Júnior, Hella vanAsperen, Luca Mortarini, Otávio C. Acevedo, Christopher Pöhlker, Leslie A. Kremper, Bruno Takeshi, Carlos A. Quesada, and Daiane V. Brondani
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CO2 ,cold pool ,convective storms ,forest fires ,gust front ,Meteorology. Climatology ,QC851-999 - Abstract
Abstract High‐frequency measurements obtained at two micrometeorological towers are investigated for a rare northward surging gust front that impacted the Amazon Tall Tower Observatory (ATTO), in central Amazon. The gust front originated from a decaying mesoscale convective system (MCS) during the morning hours of 27 December 2021 near Manaus, Amazonas state, northern Brazil, and surged north‐eastward towards the ATTO site. Large temperature drops and vigorous, persistent winds were observed at the towers which lasted for over 4 h despite the gust front being detached from its parent, decaying MCS. More importantly, the gust front was responsible for drastic increases of CO2 concentrations throughout the tower depths, which suggests that the gust front winds horizontally advected CO2‐rich air from a source upstream from the ATTO site. The CO2‐rich outflow is hypothesized to originate from downward transport and/or biomass burning from forest fires in southeastern Amazon, both ideas that are supported by large increases of aerosol concentrations measured at ATTO following the gust front passage. Our results stress the need for further investigations addressing the role played by mesoscale convective circulations in the redistribution of trace gases and aerosols in the Amazon.
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- 2024
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7. Process-evaluation of forest aerosol-cloud-climate feedback shows clear evidence from observations and large uncertainty in models
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Sara M. Blichner, Taina Yli-Juuti, Tero Mielonen, Christopher Pöhlker, Eemeli Holopainen, Liine Heikkinen, Claudia Mohr, Paulo Artaxo, Samara Carbone, Bruno Backes Meller, Cléo Quaresma Dias-Júnior, Markku Kulmala, Tuukka Petäjä, Catherine E. Scott, Carl Svenhag, Lars Nieradzik, Moa Sporre, Daniel G. Partridge, Emanuele Tovazzi, Annele Virtanen, Harri Kokkola, and Ilona Riipinen
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Science - Abstract
Abstract Natural aerosol feedbacks are expected to become more important in the future, as anthropogenic aerosol emissions decrease due to air quality policy. One such feedback is initiated by the increase in biogenic volatile organic compound (BVOC) emissions with higher temperatures, leading to higher secondary organic aerosol (SOA) production and a cooling of the surface via impacts on cloud radiative properties. Motivated by the considerable spread in feedback strength in Earth System Models (ESMs), we here use two long-term observational datasets from boreal and tropical forests, together with satellite data, for a process-based evaluation of the BVOC-aerosol-cloud feedback in four ESMs. The model evaluation shows that the weakest modelled feedback estimates can likely be excluded, but highlights compensating errors making it difficult to draw conclusions of the strongest estimates. Overall, the method of evaluating along process chains shows promise in pin-pointing sources of uncertainty and constraining modelled aerosol feedbacks.
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- 2024
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8. Global organic and inorganic aerosol hygroscopicity and its effect on radiative forcing
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Mira L. Pöhlker, Christopher Pöhlker, Johannes Quaas, Johannes Mülmenstädt, Andrea Pozzer, Meinrat O. Andreae, Paulo Artaxo, Karoline Block, Hugh Coe, Barbara Ervens, Peter Gallimore, Cassandra J. Gaston, Sachin S. Gunthe, Silvia Henning, Hartmut Herrmann, Ovid O. Krüger, Gordon McFiggans, Laurent Poulain, Subha S. Raj, Ernesto Reyes-Villegas, Haley M. Royer, David Walter, Yuan Wang, and Ulrich Pöschl
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Science - Abstract
Abstract The climate effects of atmospheric aerosol particles serving as cloud condensation nuclei (CCN) depend on chemical composition and hygroscopicity, which are highly variable on spatial and temporal scales. Here we present global CCN measurements, covering diverse environments from pristine to highly polluted conditions. We show that the effective aerosol hygroscopicity, κ, can be derived accurately from the fine aerosol mass fractions of organic particulate matter (ϵ org) and inorganic ions (ϵ inorg) through a linear combination, κ = ϵ org ⋅ κ org + ϵ inorg ⋅ κ inorg. In spite of the chemical complexity of organic matter, its hygroscopicity is well captured and represented by a global average value of κ org = 0.12 ± 0.02 with κ inorg = 0.63 ± 0.01 as the corresponding value for inorganic ions. By showing that the sensitivity of global climate forcing to changes in κ org and κ inorg is small, we constrain a critically important aspect of global climate modelling.
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- 2023
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9. African biomass burning affects aerosol cycling over the Amazon
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Bruna A. Holanda, Marco A. Franco, David Walter, Paulo Artaxo, Samara Carbone, Yafang Cheng, Sourangsu Chowdhury, Florian Ditas, Martin Gysel-Beer, Thomas Klimach, Leslie A. Kremper, Ovid O. Krüger, Jost V. Lavric, Jos Lelieveld, Chaoqun Ma, Luiz A. T. Machado, Robin L. Modini, Fernando G. Morais, Andrea Pozzer, Jorge Saturno, Hang Su, Manfred Wendisch, Stefan Wolff, Mira L. Pöhlker, Meinrat O. Andreae, Ulrich Pöschl, and Christopher Pöhlker
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Geology ,QE1-996.5 ,Environmental sciences ,GE1-350 - Abstract
Abstract Smoke from vegetation fires affects air quality, atmospheric cycling, and the climate in the Amazon rain forest. A major unknown has remained the quantity of long-range transported smoke from Africa in relation to local and regional fire emissions. Here we quantify the abundance, seasonality, and properties of African smoke in central Amazonia. We show that it accounts for ~ 60% of the black carbon concentrations during the wet season and ~ 30% during the dry season. The African smoke influences aerosol-radiation interactions across the entire Amazon, with the strongest impact on the vulnerable eastern basin, a hot spot of climate and land use change. Our findings further suggest that the direct influence of African smoke has been historically relevant for soil fertilization, the carbon and water cycles, and, thus, the development of the Amazon forest ecosystem, even in the pre-industrial era.
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- 2023
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10. Unified theoretical framework for black carbon mixing state allows greater accuracy of climate effect estimation
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Jiandong Wang, Jiaping Wang, Runlong Cai, Chao Liu, Jingkun Jiang, Wei Nie, Jinbo Wang, Nobuhiro Moteki, Rahul A. Zaveri, Xin Huang, Nan Ma, Ganzhen Chen, Zilin Wang, Yuzhi Jin, Jing Cai, Yuxuan Zhang, Xuguang Chi, Bruna A. Holanda, Jia Xing, Tengyu Liu, Ximeng Qi, Qiaoqiao Wang, Christopher Pöhlker, Hang Su, Yafang Cheng, Shuxiao Wang, Jiming Hao, Meinrat O. Andreae, and Aijun Ding
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Science - Abstract
Abstract Black carbon (BC) plays an important role in the climate system because of its strong warming effect, yet the magnitude of this effect is highly uncertain owing to the complex mixing state of aerosols. Here we build a unified theoretical framework to describe BC’s mixing states, linking dynamic processes to BC coating thickness distribution, and show its self-similarity for sites in diverse environments. The size distribution of BC-containing particles is found to follow a universal law and is independent of BC core size. A new mixing state module is established based on this finding and successfully applied in global and regional models, which increases the accuracy of aerosol climate effect estimations. Our theoretical framework links observations with model simulations in both mixing state description and light absorption quantification.
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- 2023
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11. Sink, Source or Something In‐Between? Net Effects of Precipitation on Aerosol Particle Populations
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Théodore Khadir, Ilona Riipinen, Sini Talvinen, Dominic Heslin‐Rees, Christopher Pöhlker, Luciana Rizzo, Luiz A. T. Machado, Marco A. Franco, Leslie A. Kremper, Paulo Artaxo, Tuukka Petäjä, Markku Kulmala, Peter Tunved, Annica M. L. Ekman, Radovan Krejci, and Annele Virtanen
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Geophysics. Cosmic physics ,QC801-809 - Abstract
Abstract Interactions between atmospheric aerosols, clouds, and precipitation impact Earth's radiative balance and air quality, yet remain poorly constrained. Precipitating clouds serve as major sinks for particulate matter, but recent studies suggest that precipitation may also act as a particle source. The magnitude of the sources versus sinks, particularly for cloud condensation nuclei (CCN) numbers, remain unquantified. This study analyzes multi‐year in situ observations from tropical and boreal forests, as well as Arctic marine environment, showing links between recent precipitation and enhanced particle concentrations, including CCN‐sized particles. In some cases, the magnitude of precipitation‐related source equals or surpasses corresponding removal effect. Our findings highlight the importance of cloud‐processed material in determining near‐surface particle concentrations and the value of long‐term in situ observations for understanding aerosol particle life cycle. Robust patterns emerge from sufficiently long data series, allowing for quantitative assessment of the large‐scale significance of new phenomena observed in case studies.
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- 2023
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12. Identification and quantification of giant bioaerosol particles over the Amazon rainforest
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Cybelli G. G. Barbosa, Philip E. Taylor, Marta O. Sá, Paulo R. Teixeira, Rodrigo A. F. Souza, Rachel I. Albrecht, Henrique M. J. Barbosa, Bruna Sebben, Antônio O. Manzi, Alessandro C. Araújo, Maria Prass, Christopher Pöhlker, Bettina Weber, Meinrat O. Andreae, and Ricardo H. M. Godoi
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Environmental sciences ,GE1-350 ,Meteorology. Climatology ,QC851-999 - Abstract
Abstract Eukarya dominate the coarse primary biological aerosol (PBA) above the Amazon rainforest canopy, but their vertical profile and seasonality is currently unknown. In this study, the stratification of coarse and giant PBA >5 µm were analyzed from the canopy to 300 m height at the Amazon Tall Tower Observatory in Brazil during the wet and dry seasons. We show that >2/3 of the coarse PBA were canopy debris, fungal spores commonly found on decaying matter were second most abundant (ranging from 15 to 41%), followed by pollens (up to 5%). The atmospheric roughness layer right above the canopy had the greatest giant PBA abundance. Measurements over 5 years showed an increased abundance of PBA during a low-rainfall period. Giant particles, such as pollen, are reduced at 300 m, suggesting their limited dispersal. These results give insights into the giant PBA emissions of this tropical rainforest, and present a major step in understanding the type of emitted particles and their vertical distribution.
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- 2022
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13. Extending the performance of microfluidic membrane suppressors and hyphenation with on-chip conductivity detection for ion-exchange chromatography
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Sam Wouters, Cees Bruggink, Christopher Pohl, Sebastiaan Eeltink, Chemical Engineering and Industrial Chemistry, Faculty of Engineering, Centre for Molecular Separation Science & Technology, and Chemical Engineering and Separation Science
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miniaturization ,hyphenation ,ion-exchange chromatography ,CHIPS - Abstract
A miniaturized hyphenated chip device featuring all key elements required to perform ion-exchange chromatography with suppressed conductivity detection would potentially allow high-efficiency separations of minute amounts of sample with reduced solvent consumption, which is important in e.g., clinical diagnostics and life-science research. The proposed chip-based platform would consist of three stacked chips, i.e., a module comprising the separation channel packed with anion-exchange particles (1), which is hyphenated with a chemically-regenerated microfluidic membrane suppressor chip (2), and a chip module featuring on-chip conductivity detection (3). Due to the miniaturized column dimensions, it is crucial to minimize extra-column contributions to maintain high separation efficiencies. In the present study, the possibilities of novel microfluidic membrane suppressor designs are explored with the aim of further expanding the operational range and suppression efficacy. Apart from modifying the channel layout to minimize extra-column band broadening and diffusion distances, the effect of suppressor operating temperature is presented. In addition, the performance of different membranes materials and regenerant solutions have been studied. With the optimized design and operating conditions, the microfluidic membrane suppressor is hyphenated with a commercially available capillary ion-exchange chromatography system and the system performance is demonstrated for isocratic and gradient separations of inorganic anions and organic acids. In a second part of the study, the integration of electrodes for on-chip conductivity detection was explored. The effects of different electrode design on performance in terms of linear range of detections and LOD are discussed. By implementing such detector on-chip directly after the suppressor, extra-column contributions are again lowered.
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- 2016
14. Implementation of a Dynamically Reconfigurable Processing Module for SpaceWire Networks
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Florian Dittmann, Linke, M., Jens Hagemeyer, Markus Köster, Julien Lallet, Christopher Pohl, Mario Porrmann, Julian Harris, and Jorgen Ilstad
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The ESA-project "FPGA based generic module and dynamic reconfigurator" targets the development of a hardware architecture, called DRPM (for Dynamically Reconfigurable Processing Module). The goal of the DRPM is to develop a system that allows for the adaptation of hardware components in flight at run-time. This is enabled by the implementation of an SRAM-FPGA-based partially reconfigurable core, which is embedded into a system hosting a reconfiguration controller and a system controller providing suitable interfaces for space applications. Maximum flexibility is realized by implementing SpaceWire interfaces that enable the DRPM integration into a SpaceWire network. Moreover, the SpaceWire RMAP protocol is used for remote access to registers and memory banks of the DRPM.
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- 2010
15. Reconfiguration Viewer
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Paolo Roberto Grassi, Christopher Pohl, and Mario Porrmann
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Hardware_ARITHMETICANDLOGICSTRUCTURES - Abstract
The proposed approach allows debugging of partial dynamic reconfiguration. It shows where and when FPGA areas are reconfigured at runtime.
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- 2009
16. SiLLis: A Simplified Language for Monitoring and Debugging of Reconfigurable Systems
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Paolo Roberto Grassi, Santambrogio, M., Jens Hagemeyer, Christopher Pohl, and Mario Porrmann
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- 2009
17. Manageable Dynamic Reconfiguration with EVE – Extendable VHDL Editor
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Christopher Pohl, Ralf Fuest, and Mario Porrmann
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Dynamic reconfiguration of FPGAs is a promising approach for saving resources, thus becoming attractive for industrial applications. In this paper we present a complete tool flow which enables users to create dynamically reconfigurable systems without in depth knowledge of the underlying hardware and methodologies.
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- 2009
18. vMAGIC—Automatic Code Generation for VHDL
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Mario Porrmann, Carlos Paiz, and Christopher Pohl
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Code review ,Source code ,lcsh:Computer engineering. Computer hardware ,Article Subject ,Computer science ,Interface (Java) ,Programming language ,media_common.quotation_subject ,lcsh:TK7885-7895 ,computer.software_genre ,Code refactoring ,Hardware and Architecture ,VHDL ,Code (cryptography) ,Code generation ,KPI-driven code analysis ,computer ,computer.programming_language ,media_common - Abstract
Automatic code generation is a standard method in software engineering, improving the code reliability as well as reducing the overall development time. In hardware engineering, automatic code generation is utilized within a number of development tools, the integrated code generation functionality, however, is not exposed to developers wishing to implement their own generators. In this paper, VHDL Manipulation and Generation Interface (vMAGIC), a Java library to read, manipulate, and write VHDL code is presented. The basic functionality as well as the designflow is described, stressing the advantages when designing with vMAGIC. Two real-world examples demonstrate the power of code generation in hardware engineering.
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- 2009
19. vMAGIC – VHDL Manipulation and Automation for Reliable System Development
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Christopher Pohl, Carlos Paiz, and Mario Porrmann
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- 2008
20. FPGA-in-the-Loop Simulations with CAMEL-View
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Eckehard Münch, Alfonso Gambuzza, Carlos Paiz, Christopher Pohl, and Mario Porrmann
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- 2008
21. Hardware-in-the-Loop Entwicklungsumgebung fuer informationsverarbeitende Komponenten mechatronischer Systeme
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Christopher Pohl, Carlos Paiz, and Mario Porrmann
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- 2007
22. Tropical and Boreal Forest – Atmosphere Interactions: A Review
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Paulo Artaxo, Hans-Christen Hansson, Meinrat O. Andreae, Jaana Bäck, Eliane Gomes Alves, Henrique M. J. Barbosa, Frida Bender, Efstratios Bourtsoukidis, Samara Carbone, Jinshu Chi, Stefano Decesari, Viviane R. Després, Florian Ditas, Ekaterina Ezhova, Sandro Fuzzi, Niles J. Hasselquist, Jost Heintzenberg, Bruna A. Holanda, Alex Guenther, Hannele Hakola, Liine Heikkinen, Veli-Matti Kerminen, Jenni Kontkanen, Radovan Krejci, Markku Kulmala, Jost V. Lavric, Gerrit de Leeuw, Katrianne Lehtipalo, Luiz Augusto T. Machado, Gordon McFiggans, Marco Aurelio M. Franco, Bruno Backes Meller, Fernando G. Morais, Claudia Mohr, William Morgan, Mats B. Nilsson, Matthias Peichl, Tuukka Petäjä, Maria Praß, Christopher Pöhlker, Mira L. Pöhlker, Ulrich Pöschl, Celso Von Randow, Ilona Riipinen, Janne Rinne, Luciana V. Rizzo, Daniel Rosenfeld, Maria A. F. Silva Dias, Larisa Sogacheva, Philip Stier, Erik Swietlicki, Matthias Sörgel, Peter Tunved, Aki Virkkula, Jian Wang, Bettina Weber, Ana Maria Yáñez-Serrano, Paul Zieger, Eugene Mikhailov, James N. Smith, and Jürgen Kesselmeier
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boreal forests ,tropical forests ,amazonia ,biogenic emissions: fires ,biomass burning ,aerosol particles ,climate effects ,Meteorology. Climatology ,QC851-999 - Abstract
This review presents how the boreal and the tropical forests affect the atmosphere, its chemical composition, its function, and further how that affects the climate and, in return, the ecosystems through feedback processes. Observations from key tower sites standing out due to their long-term comprehensive observations: The Amazon Tall Tower Observatory in Central Amazonia, the Zotino Tall Tower Observatory in Siberia, and the Station to Measure Ecosystem-Atmosphere Relations at Hyytiäla in Finland. The review is complemented by short-term observations from networks and large experiments. The review discusses atmospheric chemistry observations, aerosol formation and processing, physiochemical aerosol, and cloud condensation nuclei properties and finds surprising similarities and important differences in the two ecosystems. The aerosol concentrations and chemistry are similar, particularly concerning the main chemical components, both dominated by an organic fraction, while the boreal ecosystem has generally higher concentrations of inorganics, due to higher influence of long-range transported air pollution. The emissions of biogenic volatile organic compounds are dominated by isoprene and monoterpene in the tropical and boreal regions, respectively, being the main precursors of the organic aerosol fraction. Observations and modeling studies show that climate change and deforestation affect the ecosystems such that the carbon and hydrological cycles in Amazonia are changing to carbon neutrality and affect precipitation downwind. In Africa, the tropical forests are so far maintaining their carbon sink. It is urgent to better understand the interaction between these major ecosystems, the atmosphere, and climate, which calls for more observation sites, providing long-term data on water, carbon, and other biogeochemical cycles. This is essential in finding a sustainable balance between forest preservation and reforestation versus a potential increase in food production and biofuels, which are critical in maintaining ecosystem services and global climate stability. Reducing global warming and deforestation is vital for tropical forests.
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- 2022
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23. Intercomparison of Planetary Boundary Layer Heights Using Remote Sensing Retrievals and ERA5 Reanalysis over Central Amazonia
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Cléo Quaresma Dias-Júnior, Rayonil Gomes Carneiro, Gilberto Fisch, Flávio Augusto F. D’Oliveira, Matthias Sörgel, Santiago Botía, Luiz Augusto T. Machado, Stefan Wolff, Rosa Maria N. dos Santos, and Christopher Pöhlker
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Amazon forest ,El Niño ,atmospheric boundary layer ,ERA5 simulations ,GoAmazon and ATTO projects ,Science - Abstract
The atmospheric boundary layer height (zi) is a key parameter in the vertical transport of mass, energy, moisture, and chemical species between the surface and the free atmosphere. There is a lack of long-term and continuous observations of zi, however, particularly for remote regions, such as the Amazon forest. Reanalysis products, such as ERA5, can fill this gap by providing temporally and spatially resolved information on zi. In this work, we evaluate the ERA5 estimates of zi (zi-ERA5) for two locations in the Amazon and corrected them by means of ceilometer, radiosondes, and SODAR measurements (zi-experimental). The experimental data were obtained at the remote Amazon Tall Tower Observatory (ATTO) with its pristine tropical forest cover and the T3 site downwind of the city of Manaus with a mixture of forest (63%), pasture (17%), and rivers (20%). We focus on the rather typical year 2014 and the El Niño year 2015. The comparison of the experimental vs. ERA5 zi data yielded the following results: (i) zi-ERA5 underestimates zi-experimental daytime at the T3 site for both years 2014 (30%, underestimate) and 2015 (15%, underestimate); (ii) zi-ERA5 overestimates zi-experimental daytime at ATTO site (12%, overestimate); (iii) during nighttime, no significant correlation between the zi-experimental and zi-ERA5 was observed. Based on these findings, we propose a correction for the daytime zi-ERA5, for both sites and for both years, which yields a better agreement between experimental and ERA5 data. These results and corrections are relevant for studies at ATTO and the T3 site and can likely also be applied at further locations in the Amazon.
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- 2022
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24. Controlled/Living Radical Polymerization
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Krzysztof Matyjaszewski, Toshihide Yoshitani, Yasuhiro Watanabe, Tsuyoshi Ando, Masami Kamigaito, Mitsuo Sawamoto, Kotaro Satoh, Decheng Wan, Yuya Sugiyama, Kazuhiko Koumura, Takuya Shibata, Yoshio Okamoto, Sébastien Delfosse, Aurore Richel, Lionel Delaude, Albert Demonceau, Alfred F. Noels, Nicolay V. Tsarevsky, Wei Tang, Samuel J. Brooks, Shijie Ding, Maciej Radosz, Youqing Shen, Santiago Faucher, Shiping Zhu, Metin H. Acar, C. Remzi Becer, H. Alper Ondur, Şebnem Ínceoğlu, Atsushi Kajiwara, Alexandru D. Asandei, Isaac W. Moran, Gobinda Saha, Yanhui Chen, Brent S. Sumerlin, Haifeng Gao, Patricia Golas, Guillaume Louche, Robert Y. Lee, René Nagelsdiek, Petra Mela, Martina Mennicken, Helmut Keul, Martin Möller, Wim Van Camp, Filip E. Du Prez, Jean-François Lutz, Rainer Nehring, Sebastian Pfeifer, Mattijs G. J. Ten Cate, Hans G. Börner, Sharmila Muthukrishnan, Hideharu Mori, Axel H. E. Müller, Robert E. Richard, Marlene Schwarz, Shrirang Ranade, A. Ken Chan, Brent Sumerlin, Patrick McCarthy, Lindsay Bombalski, Christopher Pohl, Guido Kickelbick, Die, Krzysztof Matyjaszewski, Toshihide Yoshitani, Yasuhiro Watanabe, Tsuyoshi Ando, Masami Kamigaito, Mitsuo Sawamoto, Kotaro Satoh, Decheng Wan, Yuya Sugiyama, Kazuhiko Koumura, Takuya Shibata, Yoshio Okamoto, Sébastien Delfosse, Aurore Richel, Lionel Delaude, Albert Demonceau, Alfred F. Noels, Nicolay V. Tsarevsky, Wei Tang, Samuel J. Brooks, Shijie Ding, Maciej Radosz, Youqing Shen, Santiago Faucher, Shiping Zhu, Metin H. Acar, C. Remzi Becer, H. Alper Ondur, Şebnem Ínceoğlu, Atsushi Kajiwara, Alexandru D. Asandei, Isaac W. Moran, Gobinda Saha, Yanhui Chen, Brent S. Sumerlin, Haifeng Gao, Patricia Golas, Guillaume Louche, Robert Y. Lee, René Nagelsdiek, Petra Mela, Martina Mennicken, Helmut Keul, Martin Möller, Wim Van Camp, Filip E. Du Prez, Jean-François Lutz, Rainer Nehring, Sebastian Pfeifer, Mattijs G. J. Ten Cate, Hans G. Börner, Sharmila Muthukrishnan, Hideharu Mori, Axel H. E. Müller, Robert E. Richard, Marlene Schwarz, Shrirang Ranade, A. Ken Chan, Brent Sumerlin, Patrick McCarthy, Lindsay Bombalski, Christopher Pohl, Guido Kickelbick, and Die
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- Polymerization--Congresses, Free radical reactions--Congresses
- Published
- 2006
25. Electrochemical Biochip Assays Based on Anti-idiotypic Antibodies for Rapid and Automated On-Site Detection of Low Molecular Weight Toxins
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Katharina Schulz, Christopher Pöhlmann, Richard Dietrich, Erwin Märtlbauer, and Thomas Elßner
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electrochemical biochip ,on-site detection ,pBDi ,competitive immunoassay ,anti-idiotypic antibodies ,aflatoxins ,Chemistry ,QD1-999 - Abstract
Phycotoxins and mycotoxins, such as paralytic shellfish poisoning toxins, type A trichothecenes, and aflatoxins are among the most toxic low molecular weight toxins associated with human poisoning incidents through the consumption of naturally contaminated food. Therefore, there is an utmost need for rapid and sensitive on-site detection systems. Herein, an electrochemical biochip for fast detection of saxitoxin, T-2 toxin as well as aflatoxin M1 and their corresponding congeners, respectively, using a portable and fully automated detection platform (pBDi, portable BioDetector integrated) was developed. Toxin analysis is facilitated upon the biochip via an indirect competitive immunoassay using toxin-specific antibodies combined with anti-idiotypic antibodies. The developed biochips enable detection in the low ng/mL-range within 17 min. Moreover, the assays cover a wide linear working range of 2–3 orders of magnitude above the limit of detection with an inter-chip coefficient of variation lower than 15%. The broad specificity of the employed antibodies which react with a large number of congeners within the respective toxin group allows efficient screening of contaminated samples for the presence of these low molecular weight toxins. With respect to the analysis of human urine samples, we focused here on the detection of saxitoxin, HT-2 toxin, and aflatoxin M1, all known as biomarkers of acute toxin exposure. Overall, it was proved that the developed biochip assays can be used to rapidly and reliably identify severe intoxications caused by these low molecular weight toxins.
- Published
- 2019
- Full Text
- View/download PDF
26. Innovative and Highly Sensitive Detection of Clostridium perfringens Enterotoxin Based on Receptor Interaction and Monoclonal Antibodies
- Author
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Thea Neumann, Maren Krüger, Jasmin Weisemann, Stefan Mahrhold, Daniel Stern, Martin B. Dorner, Cécile Feraudet-Tarisse, Christopher Pöhlmann, Katharina Schulz, Ute Messelhäußer, Dagmar Rimek, Frank Gessler, Thomas Elßner, Stéphanie Simon, Andreas Rummel, and Brigitte G. Dorner
- Subjects
C. perfringens enterotoxin CPE ,Clostridium perfringens ,monoclonal antibodies ,receptor claudin-4 ,stationary lab-based detection ,mobile on-site detection ,Medicine - Abstract
Clostridium perfringens enterotoxin (CPE) regularly causes food poisoning and antibiotic-associated diarrhea; therefore, reliable toxin detection is crucial. To this aim, we explored stationary and mobile strategies to detect CPE either exclusively by monoclonal antibodies (mAbs) or, alternatively, by toxin-enrichment via the cellular receptor of CPE, claudin-4, and mAb detection. Among the newly generated mAbs, we identified nine CPE-specific mAbs targeting five distinct epitopes, among them mAbs recognizing CPE bound to claudin-4 or neutralizing CPE activity in vitro. In surface plasmon resonance experiments, all mAbs and claudin-4 revealed excellent affinities towards CPE, ranging from 0.05 to 2.3 nM. Integrated into sandwich enzyme-linked immunosorbent assays (ELISAs), the most sensitive mAb/mAb and claudin-4/mAb combinations achieved similar detection limits of 0.3 pg/mL and 1.0 pg/mL, respectively, specifically detecting recombinant CPE from spiked feces and native CPE from 30 different C. perfringens culture supernatants. The implementation of mAb- and receptor-based ELISAs into a mobile detection platform enabled the fast detection of CPE, which will be helpful in clinical laboratories to diagnose diarrhea of assumed bacterial origin. In conclusion, we successfully employed an endogenous receptor and novel high affinity mAbs for highly sensitive and specific CPE-detection. These tools will be useful for both basic and applied research.
- Published
- 2021
- Full Text
- View/download PDF
27. Multiplex Immunoassay Techniques for On-Site Detection of Security Sensitive Toxins
- Author
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Christopher Pöhlmann and Thomas Elßner
- Subjects
security sensitive toxins ,multiplex immunoassay platforms ,on-site detection ,optical biosensor ,electrochemical biosensor ,proteotoxins ,Medicine - Abstract
Biological toxins are a heterogeneous group of high molecular as well as low molecular weight toxins produced by living organisms. Due to their physical and logistical properties, biological toxins are very attractive to terrorists for use in acts of bioterrorism. Therefore, among the group of biological toxins, several are categorized as security relevant, e.g., botulinum neurotoxins, staphylococcal enterotoxins, abrin, ricin or saxitoxin. Additionally, several security sensitive toxins also play a major role in natural food poisoning outbreaks. For a prompt response to a potential bioterrorist attack using biological toxins, first responders need reliable, easy-to-use and highly sensitive methodologies for on-site detection of the causative agent. Therefore, the aim of this review is to present on-site immunoassay platforms for multiplex detection of biological toxins. Furthermore, we introduce several commercially available detection technologies specialized for mobile or on-site identification of security sensitive toxins.
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- 2020
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28. Elemental Mixing State of Aerosol Particles Collected in Central Amazonia during GoAmazon2014/15
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Matthew Fraund, Don Q. Pham, Daniel Bonanno, Tristan H. Harder, Bingbing Wang, Joel Brito, Suzane S. de Sá, Samara Carbone, Swarup China, Paulo Artaxo, Scot T. Martin, Christopher Pöhlker, Meinrat O. Andreae, Alexander Laskin, Mary K. Gilles, and Ryan C. Moffet
- Subjects
mixing state ,Amazon ,elemental composition ,aerosol ,STXM ,SEM ,EDX ,diversity ,aging ,Meteorology. Climatology ,QC851-999 - Abstract
Two complementary techniques, Scanning Transmission X-ray Microscopy/Near Edge Fine Structure spectroscopy (STXM/NEXAFS) and Scanning Electron Microscopy/Energy Dispersive X-ray spectroscopy (SEM/EDX), have been quantitatively combined to characterize individual atmospheric particles. This pair of techniques was applied to particle samples at three sampling sites (ATTO, ZF2, and T3) in the Amazon basin as part of the Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) field campaign during the dry season of 2014. The combined data was subjected to k-means clustering using mass fractions of the following elements: C, N, O, Na, Mg, P, S, Cl, K, Ca, Mn, Fe, Ni, and Zn. Cluster analysis identified 12 particle types across different sampling sites and particle sizes. Samples from the remote Amazon Tall Tower Observatory (ATTO, also T0a) exhibited less cluster variety and fewer anthropogenic clusters than samples collected at the sites nearer to the Manaus metropolitan region, ZF2 (also T0t) or T3. Samples from the ZF2 site contained aged/anthropogenic clusters not readily explained by transport from ATTO or Manaus, possibly suggesting the effects of long range atmospheric transport or other local aerosol sources present during sampling. In addition, this data set allowed for recently established diversity parameters to be calculated. All sample periods had high mixing state indices (χ) that were >0.8. Two individual particle diversity (Di) populations were observed, with particles 0.5 µm particles having a Di of ~3.6, which likely correspond to fresh and aged aerosols, respectively. The diversity parameters determined by the quantitative method presented here will serve to aid in the accurate representation of aerosol mixing state, source apportionment, and aging in both less polluted and more developed environments in the Amazon Basin.
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- 2017
- Full Text
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29. Simultaneous Quantitation of 2- and 4-Methylimidazole in Carbonated Drinks.
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Leo (Jinyuan) Wang, Xiaodong Liu, Christopher Pohl, and William Schnute
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HIGH performance liquid chromatography ,TANDEM mass spectrometry ,CARCINOGENS ,CARBONATED beverages - Abstract
The article reports on the use of ultrahigh performance liquid chromatography tandem mass spectrometry (UHPLC MS-MS) from Dionex Corp. to identify the quantification of 2- and 4-methylimidazoles in carbonated drinks. It states that the chemicals are by-products produced during the manufacturing of caramel coloring ingredients used to darken food products such as carbonated beverages. It notes that the quantification of the two carcinogens in foods is vital for food safety and human health.
- Published
- 2011
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