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Sökning: WFRF:(Pfeifer Thomas)

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6.
  • Hermann, Markus, et al. (författare)
  • An optical particle size spectrometer for aircraft-borne measurements in IAGOS-CARIBIC
  • 2016
  • Ingår i: Atmospheric Measurement Techniques. - : Copernicus GmbH. - 1867-1381 .- 1867-8548. ; 9:5, s. 2179-2194
  • Tidskriftsartikel (refereegranskat)abstract
    • The particle number size distribution is an important parameter to characterize the atmospheric aerosol and its influence on the Earth's climate. Here we describe a new optical particle size spectrometer (OPSS) for measurements of the accumulation mode particle number size distribution in the tropopause region on board a passenger aircraft (IAGOS-CARIBIC observatory: In-service Aircraft for a Global Observing System - Civil Aircraft for Regular Investigation of the Atmosphere Based on an Instrument Container). A modified KS93 particle sensor from RION Co., Ltd., together with a new airflow system and a dedicated data acquisition system, is the key component of the CARIBIC OPSS. The instrument records individual particle pulse signal curves in the particle size range 130-1110 nm diameter (for a particle refractive index of 1.47-i0.006) together with a time stamp and thus allows the post-flight choice of the time resolution and the size distribution bin width. The CARIBIC OPSS has a 50 % particle detection diameter of 152 nm and a maximum asymptotic counting efficiency of 98 %. The instrument's measurement performance shows no pressure dependency and no particle coincidence for free tropospheric conditions. The size response function of the CARIBIC OPSS was obtained by a polystyrene latex calibration in combination with model calculations. Particle number size distributions measured with the new OPSS in the lowermost stratosphere agreed within a factor of 2 in concentration with balloon-borne measurements over western North America. Since June 2010 the CARIBIC OPSS is deployed once per month in the IAGOS-CARIBIC observatory.
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7.
  • Ueda, Kiyoshi, et al. (författare)
  • Roadmap on photonic, electronic and atomic collision physics : I. Light-matter interaction
  • 2019
  • Ingår i: Journal of Physics B. - : IOP PUBLISHING LTD. - 0953-4075 .- 1361-6455. ; 52:17
  • Tidskriftsartikel (refereegranskat)abstract
    • We publish three Roadmaps on photonic, electronic and atomic collision physics in order to celebrate the 60th anniversary of the ICPEAC conference. In Roadmap I, we focus on the light-matter interaction. In this area, studies of ultrafast electronic and molecular dynamics have been rapidly growing, with the advent of new light sources such as attosecond lasers and x-ray free electron lasers. In parallel, experiments with established synchrotron radiation sources and femtosecond lasers using cutting-edge detection schemes are revealing new scientific insights that have never been exploited. Relevant theories are also being rapidly developed. Target samples for photon-impact experiments are expanding from atoms and small molecules to complex systems such as biomolecules, fullerene, clusters and solids. This Roadmap aims to look back along the road, explaining the development of these fields, and look forward, collecting contributions from twenty leading groups from the field.
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  • Aad, G., et al. (författare)
  • 2012
  • Tidskriftsartikel (refereegranskat)
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  • Aad, G., et al. (författare)
  • 2010
  • swepub:Mat__t
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10.
  • Aad, G., et al. (författare)
  • Studies of the performance of the ATLAS detector using cosmic-ray muons
  • 2011
  • Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 71:3
  • Tidskriftsartikel (refereegranskat)abstract
    • Muons from cosmic-ray interactions in the atmosphere provide a high-statistics source of particles that can be used to study the performance and calibration of the ATLAS detector. Cosmic-ray muons can penetrate to the cavern and deposit energy in all detector subsystems. Such events have played an important role in the commissioning of the detector since the start of the installation phase in 2005 and were particularly important for understanding the detector performance in the time prior to the arrival of the first LHC beams. Global cosmic-ray runs were undertaken in both 2008 and 2009 and these data have been used through to the early phases of collision data-taking as a tool for calibration, alignment and detector monitoring. These large datasets have also been used for detector performance studies, including investigations that rely on the combined performance of different subsystems. This paper presents the results of performance studies related to combined tracking, lepton identification and the reconstruction of jets and missing transverse energy. Results are compared to expectations based on a cosmic-ray event generator and a full simulation of the detector response.
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  • Charpentier Ljungqvist, Fredrik, 1982-, et al. (författare)
  • Regional Patterns of Late Medieval and Early Modern European Building Activity Revealed by Felling Dates
  • 2022
  • Ingår i: Frontiers in Ecology and Evolution. - : Frontiers Media SA. - 2296-701X. ; 9
  • Tidskriftsartikel (refereegranskat)abstract
    • Although variations in building activity are a useful indicator of societal well-being and demographic development, historical datasets for larger regions and longer periods are still rare. Here, we present 54,045 annually precise dendrochronological felling dates from historical construction timber from across most of Europe between 1250 and 1699 CE to infer variations in building activity. We use geostatistical techniques to compare spatiotemporal dynamics in past European building activity against independent demographic, economic, social and climatic data. We show that the felling dates capture major geographical patterns of demographic trends, especially in regions with dense data coverage. A particularly strong negative association is found between grain prices and the number of felling dates. In addition, a significant positive association is found between the number of felling dates and mining activity. These strong associations, with well-known macro-economic indicators from pre-industrial Europe, corroborate the use of felling dates as an independent source for exploring large-scale fluctuations of societal well-being and demographic development. Three prominent examples are the building boom in the Hanseatic League region of northeastern Germany during the 13th century, the onset of the Late Medieval Crisis in much of Europec. 1300, and the cessation of building activity in large parts of central Europe during armed conflicts such as the Thirty Years’ War (1618–1648 CE). Despite new insights gained from our European-wide felling date inventory, further studies are needed to investigate changes in construction activity of high versus low status buildings, and of urban versus rural buildings, and to compare those results with a variety of historical documentary sources and natural proxy archives.
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  • Ertel, Dominik, et al. (författare)
  • Influence of nuclear dynamics on molecular attosecond photoelectron interferometry
  • 2023
  • Ingår i: Science Advances. - 2375-2548. ; 9:35
  • Tidskriftsartikel (refereegranskat)abstract
    • In extreme ultraviolet spectroscopy, the photoionization process occurring in a molecule due to the absorption of a single photon can trigger an ultrafast nuclear motion in the cation. Taking advantage of attosecond photoelectron interferometry, where the absorption of the extreme ultraviolet photon is accompanied by the exchange of an additional infrared quantum of light, one can investigate the influence of nuclear dynamics by monitoring the characteristics of the photoelectron spectra generated by the two-color field. Here, we show that attosecond photoelectron interferometry is sensitive to the nuclear response by measuring the two-color photoionization spectra in a mixture of methane (CH4) and deuteromethane (CD4). The effect of the different nuclear evolution in the two isotopologues manifests itself in the modification of the amplitude and contrast of the oscillations of the photoelectron peaks. Our work indicates that nuclear dynamics can affect the coherence properties of the electronic wave packet emitted by photoionization on a time scale as short as a few femtoseconds.
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  • Khani, Sajjad, et al. (författare)
  • Cold-induced expression of a truncated adenylyl cyclase 3 acts as rheostat to brown fat function
  • 2024
  • Ingår i: Nature Metabolism. - 2522-5812. ; 6:6, s. 1053-1075
  • Tidskriftsartikel (refereegranskat)abstract
    • Promoting brown adipose tissue (BAT) activity innovatively targets obesity and metabolic disease. While thermogenic activation of BAT is well understood, the rheostatic regulation of BAT to avoid excessive energy dissipation remains ill-defined. Here, we demonstrate that adenylyl cyclase 3 (AC3) is key for BAT function. We identified a cold-inducible promoter that generates a 5′ truncated AC3 mRNA isoform (Adcy3-at), whose expression is driven by a cold-induced, truncated isoform of PPARGC1A (PPARGC1A-AT). Male mice lacking Adcy3-at display increased energy expenditure and are resistant to obesity and ensuing metabolic imbalances. Mouse and human AC3-AT are retained in the endoplasmic reticulum, unable to translocate to the plasma membrane and lack enzymatic activity. AC3-AT interacts with AC3 and sequesters it in the endoplasmic reticulum, reducing the pool of adenylyl cyclases available for G-protein-mediated cAMP synthesis. Thus, AC3-AT acts as a cold-induced rheostat in BAT, limiting adverse consequences of cAMP activity during chronic BAT activation. 
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  • Madueño, Leizel, et al. (författare)
  • A new method to measure real-world respiratory tract deposition of inhaled ambient black carbon
  • 2019
  • Ingår i: Environmental Pollution. - : Elsevier BV. - 0269-7491. ; 248, s. 295-303
  • Tidskriftsartikel (refereegranskat)abstract
    • In this study, we present the development of a mobile system to measure real-world total respiratory tract deposition of inhaled ambient black carbon (BC). Such information can be used to supplement the existing knowledge on air pollution-related health effects, especially in the regions where the use of standard methods and intricate instrumentation is limited. The study is divided in two parts. Firstly, we present the design of portable system and methodology to evaluate the exhaled air BC content. We demonstrate that under real-world conditions, the proposed system exhibit negligible particle losses, and can additionally be used to determine the minute ventilation. Secondly, exemplary experimental data from the system is presented. A feasibility study was conducted in the city of La Paz, Bolivia. In a pilot experiment, we found that the cumulative total respiratory tract deposition dose over 1-h commuting trip would result in approximately 2.6 μg of BC. This is up to 5 times lower than the values obtained from conjectural approach (e.g. using physical parameters from previously reported worksheets). Measured total respiratory tract deposited BC fraction varied from 39% to 48% during walking and commuting inside a micro-bus, respectively. To the best of our knowledge, no studies focusing on experimental determination of real-world deposition dose of BC have been performed in developing regions. This can be especially important because the BC mass concentration is significant and determines a large fraction of particle mass concentration. In this work, we propose a potential method, recommendations, as well as the limitations in establishing an easy and relatively cheap way to estimate the respiratory tract deposition of BC. In this study we present a novel method to measure real-world respiratory tract deposition dose of Black Carbon. Results from a pilot study in La Paz, Bolivia, are presented.
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  • Naderi, Ali, et al. (författare)
  • Sulfoethylated nanofibrillated cellulose : Production and properties
  • 2017
  • Ingår i: Carbohydrate Polymers. - : Elsevier. - 0144-8617 .- 1879-1344. ; 169, s. 515-523
  • Tidskriftsartikel (refereegranskat)abstract
    • Sulfoethylated nanofibrillated cellulose (NFCsulf) was produced by an industrially relevant process. The properties of the NFCsulf were compared with those of carboxymethylated nanofibrillated cellulose (NFCcarb), which has been identified as an attractive NFC for several industrial applications. The investigations revealed that NFCsulf is characterized by a higher degree of fibrillation and has superior redispersion properties. Furthermore, NFCsulf displays higher stability in varying pH values as compared to NFCcarb. Hence, NFCsulf may be a more attractive alternative than NFCcarb in applications such as rheological modifiers or adsorbing components in personal care products, in which the performance of NFC must remain unaffected in varying ambient conditions. The superior properties of NFCsulf compared to NFCcarb were proposed to be due to the combination of the unique chemical characteristics of the sulfoethylated reagent, and the larger size of the sulfonate group compared to the carboxymethyl group.
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  • Neumann, Hartmut P., et al. (författare)
  • 65 YEARS OF THE DOUBLE HELIX Genetics informs precision practice in the diagnosis and management of pheochromocytoma
  • 2018
  • Ingår i: Endocrine-Related Cancer. - : BIOSCIENTIFICA LTD. - 1351-0088 .- 1479-6821. ; 25:8, s. T201-T219
  • Forskningsöversikt (refereegranskat)abstract
    • Although the authors of the present review have contributed to genetic discoveries in the field of pheochromocytoma research, we can legitimately ask whether these advances have led to improvements in the diagnosis and management of patients with pheochromocytoma. The answer to this question is an emphatic Yes! In the field of molecular genetics, the well-established axiom that familial (genetic) pheochromocytoma represents 10% of all cases has been overturned, with amp;gt;35% of cases now attributable to germline disease-causing mutations. Furthermore, genetic pheochromocytoma can now be grouped into five different clinical presentation types in the context of the ten known susceptibility genes for pheochromocytoma-associated syndromes. We now have the tools to diagnose patients with genetic pheochromocytoma, identify germline mutation carriers and to offer gene-informed medical management including enhanced surveillance and prevention. Clinically, we now treat an entire family of tumors of the paraganglia, with the exact phenotype varying by specific gene. In terms of detection and classification, simultaneous advances in biochemical detection and imaging localization have taken place, and the histopathology of the paraganglioma tumor family has been revised by immunohistochemical-genetic classification by gene-specific antibody immunohistochemistry. Treatment options have also been substantially enriched by the application of minimally invasive and adrenal-sparing surgery. Finally and most importantly, it is now widely recognized that patients with genetic pheochromocytoma/paraganglioma syndromes should be treated in specialized centers dedicated to the diagnosis, treatment and surveillance of this rare neoplasm.
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  • Penninckx, Freddy, et al. (författare)
  • Letter from the ESCP Executive
  • 2011
  • Ingår i: Colorectal Disease. - : Wiley. - 1462-8910 .- 1463-1318. ; 13:10, s. 1188-1189
  • Tidskriftsartikel (refereegranskat)
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  • Pfeifer, Marion, et al. (författare)
  • Tropical forest canopies and their relationships with climate and disturbance : results from a global dataset of consistent field-based measurements
  • 2018
  • Ingår i: Forest Ecosystems. - : Elsevier BV. - 2095-6355 .- 2197-5620. ; 5:7
  • Tidskriftsartikel (refereegranskat)abstract
    • BackgroundCanopy structure, defined by leaf area index (LAI), fractional vegetation cover (FCover) and fraction of absorbed photosynthetically active radiation (fAPAR), regulates a wide range of forest functions and ecosystem services. Spatially consistent field-measurements of canopy structure are however lacking, particularly for the tropics.MethodsHere, we introduce the Global LAI database: a global dataset of field-based canopy structure measurements spanning tropical forests in four continents (Africa, Asia, Australia and the Americas). We use these measurements to test for climate dependencies within and across continents, and to test for the potential of anthropogenic disturbance and forest protection to modulate those dependences.ResultsUsing data collected from 887 tropical forest plots, we show that maximum water deficit, defined across the most arid months of the year, is an important predictor of canopy structure, with all three canopy attributes declining significantly with increasing water deficit. Canopy attributes also increase with minimum temperature, and with the protection of forests according to both active (within protected areas) and passive measures (through topography). Once protection and continent effects are accounted for, other anthropogenic measures (e.g. human population) do not improve the model.ConclusionsWe conclude that canopy structure in the tropics is primarily a consequence of forest adaptation to the maximum water deficits historically experienced within a given region. Climate change, and in particular changes in drought regimes may thus affect forest structure and function, but forest protection may offer some resilience against this effect.
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  • Pfeifer, Verena, et al. (författare)
  • Energy Band Alignment between Anatase and Rutile TiO2
  • 2013
  • Ingår i: Journal of Physical Chemistry A. - : American Chemical Society (ACS). - 1089-5639 .- 1520-5215 .- 1948-7185. ; 4:23, s. 4182-
  • Tidskriftsartikel (refereegranskat)abstract
    • Using photoelectron spectroscopy, the interface formation of anatase and rutile TiO2 with RuO2 and tin-doped indium oxide (ITO) is studied. It is consistently found that the valence band maximum of rutile is 0.7 ± 0.1 eV above that of anatase. The alignment is confirmed by electronic structure calculations, which further show that the alignment is related to the splitting of the energy bands formed by the O 2pz lone-pair orbitals. The alignment can explain the different electron concentrations in doped anatase and rutile and the enhanced photocatalytic activity of mixed phase particles.
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20.
  • Schmid, Georg, et al. (författare)
  • Tracing charge transfer in argon dimers by XUV-pump IR-probe experiments at FLASH
  • 2019
  • Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 151:8
  • Tidskriftsartikel (refereegranskat)abstract
    • Charge transfer (CT) at avoided crossings of excited ionized states of argon dimers is observed using a two-color pump-probe experiment at the free-electron laser in Hamburg (FLASH). The process is initiated by the absorption of three 27-eV-photons from the pump pulse, which leads to the population of Ar2+*-Ar states. Due to nonadiabatic coupling between these one-site doubly ionized states and two-site doubly ionized states of the type Ar+*-Ar+, CT can take place leading to the population of the latter states. The onset of this process is probed by a delayed infrared (800 nm) laser pulse. The latter ionizes the dimers populating repulsive Ar2+ -Ar+ states, which then undergo a Coulomb explosion. From the delay-dependent yields of the obtained Ar2+ and Ar+ ions, the lifetime of the charge-transfer process is extracted. The obtained experimental value of (531 ± 136) fs agrees well with the theoretical value computed from Landau-Zener probabilities.
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21.
  • Waldhuber, Anna, et al. (författare)
  • Uropathogenic Escherichia coli strain CFT073 disrupts NLRP3 inflammasome activation
  • 2016
  • Ingår i: Journal of Clinical Investigation. - 0021-9738. ; 126:7, s. 36-2425
  • Tidskriftsartikel (refereegranskat)abstract
    • Successful bacterial pathogens produce an array of virulence factors that allow subversion of the immune system and persistence within the host. For example, uropathogenic Escherichia coli strains, such as CFT073, express Toll/IL-1 receptor-containing (TIR-containing) protein C (TcpC), which impairs TLR signaling, thereby suppressing innate immunity in the urinary tract and enhancing persistence in the kidneys. Here, we have reported that TcpC also reduces secretion of IL-1β by directly interacting with the NACHT leucin-rich repeat PYD protein 3 (NLRP3) inflammasome, which is crucial for recognition of pathogens within the cytosol. At a low MOI, IL-1β secretion was minimal in CFT073-infected macrophages; however, IL-1β release was markedly increased in macrophages infected with CFT073 lacking tcpC. Induction of IL-1β secretion by CFT073 and tcpC-deficient CFT073 required the NLRP3 inflammasome. TcpC attenuated activation of the NLRP3 inflammasome by binding both NLRP3 and caspase-1 and thereby preventing processing and activation of caspase-1. Moreover, in a murine urinary tract infection model, CFT073 infection rapidly induced expression of the NLRP3 inflammasome in the bladder mucosa; however, the presence of TcpC in WT CFT073 reduced IL-1β levels in the urine of infected mice. Together, these findings illustrate how uropathogenic E. coli use the multifunctional virulence factor TcpC to attenuate innate immune responses in the urinary tract.
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  • Aad, G., et al. (författare)
  • 2013
  • swepub:Mat__t (refereegranskat)
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  • Aad, G., et al. (författare)
  • 2011
  • swepub:Mat__t
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  • Aad, G., et al. (författare)
  • 2012
  • swepub:Mat__t (refereegranskat)
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  • 2011
  • swepub:Mat__t
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  • Aad, G., et al. (författare)
  • 2012
  • swepub:Mat__t (refereegranskat)
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  • Aad, G., et al. (författare)
  • 2010
  • swepub:Mat__t
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  • Aad, G., et al. (författare)
  • 2010
  • swepub:Mat__t
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  • Aad, G., et al. (författare)
  • 2010
  • swepub:Mat__t
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