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| 3. |
- Abat, E., et al.
(författare)
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The ATLAS TRT end-cap detectors
- 2008
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Ingår i: Journal of Instrumentation. - 1748-0221. ; 3
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Tidskriftsartikel (refereegranskat)abstract
- The ATLAS TRT end-cap is a tracking drift chamber using 245,760 individual tubular drift tubes. It is a part of the TRT tracker which consist of the barrel and two end-caps. The TRT end-caps cover the forward and backward pseudo-rapidity region 1.0 < vertical bar eta vertical bar < 2.0, while the TRT barrel central eta region vertical bar eta vertical bar < 1.0. The TRT system provides a combination of continuous tracking with many measurements in individual drift tubes ( or straws) and of electron identification based on transition radiation from fibers or foils interleaved between the straws themselves. Along with other two sub-systems, namely the Pixel detector and Semi Conductor Tracker (SCT), the TRT constitutes the ATLAS Inner Detector. This paper describes the recently completed and installed TRT end-cap detectors, their design, assembly, integration and the acceptance tests applied during the construction.
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| 4. |
- Abat, E., et al.
(författare)
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The ATLAS Transition Radiation Tracker (TRT) proportional drift tube: design and performance
- 2008
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Ingår i: Journal of Instrumentation. - 1748-0221. ; 3:2
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Tidskriftsartikel (refereegranskat)abstract
- A straw proportional counter is the basic element of the ATLAS Transition Radiation Tracker (TRT). Its detailed properties as well as the main properties of a few TRT operating gas mixtures are described. Particular attention is paid to straw tube performance in high radiation conditions and to its operational stability.
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| 5. |
- Abat, E., et al.
(författare)
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The ATLAS TRT barrel detector
- 2008
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Ingår i: Journal of Instrumentation. - 1748-0221. ; 3
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Tidskriftsartikel (refereegranskat)abstract
- The ATLAS TRT barrel is a tracking drift chamber using 52,544 individual tubular drift tubes. It is one part of the ATLAS Inner Detector, which consists of three sub-systems: the pixel detector spanning the radius range 4 to 20 cm, the semiconductor tracker (SCT) from 30 to 52 cm, and the transition radiation tracker ( TRT) from 56 to 108 cm. The TRT barrel covers the central pseudo-rapidity region |eta| < 1, while the TRT endcaps cover the forward and backward eta regions. These TRT systems provide a combination of continuous tracking with many measurements in individual drift tubes ( or straws) and of electron identification based on transition radiation from fibers or foils interleaved between the straws themselves. This paper describes the recently-completed construction of the TRT Barrel detector, including the quality control procedures used in the fabrication of the detector.
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| 6. |
- Abat, E., et al.
(författare)
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The ATLAS TRT electronics
- 2008
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Ingår i: Journal of Instrumentation. - 1748-0221. ; 3:6
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Tidskriftsartikel (refereegranskat)abstract
- The ATLAS inner detector consists of three sub-systems: the pixel detector spanning the radius range 4cm-20cm, the semiconductor tracker at radii from 30 to 52 cm, and the transition radiation tracker (TRT), tracking from 56 to 107 cm. The TRT provides a combination of continuous tracking with many projective measurements based on individual drift tubes (or straws) and of electron identification based on transition radiation from fibres or foils interleaved between the straws themselves. This paper describes the on and off detector electronics for the TRT as well as the TRT portion of the data acquisition (DAQ) system.
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| 7. |
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| 8. |
- Kattge, Jens, et al.
(författare)
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TRY plant trait database - enhanced coverage and open access
- 2020
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Ingår i: Global Change Biology. - : Wiley-Blackwell. - 1354-1013 .- 1365-2486. ; 26:1, s. 119-188
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Tidskriftsartikel (refereegranskat)abstract
- Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives.
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| 10. |
- Sartelli, Massimo, et al.
(författare)
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Ten golden rules for optimal antibiotic use in hospital settings: the WARNING call to action
- 2023
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Ingår i: WORLD JOURNAL OF EMERGENCY SURGERY. - 1749-7922. ; 18:1
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Forskningsöversikt (refereegranskat)abstract
- Antibiotics are recognized widely for their benefits when used appropriately. However, they are often used inappropriately despite the importance of responsible use within good clinical practice. Effective antibiotic treatment is an essential component of universal healthcare, and it is a global responsibility to ensure appropriate use. Currently, pharmaceutical companies have little incentive to develop new antibiotics due to scientific, regulatory, and financial barriers, further emphasizing the importance of appropriate antibiotic use. To address this issue, the Global Alliance for Infections in Surgery established an international multidisciplinary task force of 295 experts from 115 countries with different backgrounds. The task force developed a position statement called WARNING (Worldwide Antimicrobial Resistance National/International Network Group) aimed at raising awareness of antimicrobial resistance and improving antibiotic prescribing practices worldwide. The statement outlined is 10 axioms, or "golden rules," for the appropriate use of antibiotics that all healthcare workers should consistently adhere in clinical practice.
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| 14. |
- Adiels, Lars, 1952-, et al.
(författare)
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Test of CP violation with K0 and K‾0 at LEAR
- 1985
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Ingår i: Physics with antiprotons at LEAR in the ACOL era. - Gif sur Yvette : Editions Frontières. - 2863320351 ; , s. 467-482
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 15. |
- Carlsson, P. T. M., et al.
(författare)
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Comparison of isoprene chemical mechanisms under atmospheric night-time conditions in chamber experiments: evidence of hydroperoxy aldehydes and epoxy products from NO3 oxidation
- 2023
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Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 23:5, s. 3147-3180
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Tidskriftsartikel (refereegranskat)abstract
- The gas-phase reaction of isoprene with the nitrate radical (NO3) was investigated in experiments in the outdoor SAPHIR chamber under atmospherically relevant conditions specifically with respect to the chemical lifetime and fate of nitrato-organic peroxy radicals (RO2). Observations of organic products were compared to concentrations expected from different chemical mechanisms: (1) the Master Chemical Mechanism, which simplifies the NO3 isoprene chemistry by only considering one RO2 isomer; (2) the chemical mechanism derived from experiments in the Caltech chamber, which considers different RO2 isomers; and (3) the FZJ-NO3 isoprene mechanism derived from quantum chemical calculations, which in addition to the Caltech mechanism includes equilibrium reactions of RO(2 )isomers, unimolecular reactions of nitrate RO(2 )radicals and epoxidation reactions of nitrate alkoxy radicals. Measurements using mass spectrometer instruments give evidence that the new reactions pathways predicted by quantum chemical calculations play a role in the NO3 oxidation of isoprene. Hydroperoxy aldehyde (HPALD) species, which are specific to unimolecular reactions of nitrate RO2, were detected even in the presence of an OH scavenger, excluding the possibility that concurrent oxidation by hydroxyl radicals (OH) is responsible for their formation. In addition, ion signals at masses that can be attributed to epoxy compounds, which are specific to the epoxidation reaction of nitrate alkoxy radicals, were detected. Measurements of methyl vinyl ketone (MVK) and methacrolein (MACR) concentrations confirm that the decomposition of nitrate alkoxy radicals implemented in the Caltech mechanism cannot compete with the ring-closure reactions predicted by quantum chemical calculations. The validity of the FZJ-NO3 isoprene mechanism is further supported by a good agreement between measured and simulated hydroxyl radical (OH) reactivity. Nevertheless, the FZJ-NO3 isoprene mechanism needs further investigations with respect to the absolute importance of unimolecular reactions of nitrate RO2 and epoxidation reactions of nitrate alkoxy radicals. Absolute concentrations of specific organic nitrates such as nitrate hydroperoxides would be required to experimentally determine product yields and branching ratios of reactions but could not be measured in the chamber experiments due to the lack of calibration standards for these compounds. The temporal evolution of mass traces attributed to product species such as nitrate hydroperoxides, nitrate carbonyl and nitrate alcohols as well as hydroperoxy aldehydes observed by the mass spectrometer instruments demonstrates that further oxidation by the nitrate radical and ozone at atmospheric concentrations is small on the timescale of one night (12 h) for typical oxidant concentrations. However, oxidation by hydroxyl radicals present at night and potentially also produced from the decomposition of nitrate alkoxy radicals can contribute to their nocturnal chemical loss.
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| 22. |
- Tsiligiannis, Epameinondas, et al.
(författare)
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A Four Carbon Organonitrate as a Significant Product of Secondary Isoprene Chemistry
- 2022
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Ingår i: Geophysical Research Letters. - : American Geophysical Union (AGU). - 0094-8276 .- 1944-8007. ; 49:11
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Tidskriftsartikel (refereegranskat)abstract
- Oxidation of isoprene by nitrate radicals (NO3) or by hydroxyl radicals (OH) under high NOx conditions forms a substantial amount of organonitrates (ONs). ONs impact NOx concentrations and consequently ozone formation while also contributing to secondary organic aerosol. Here we show that the ONs with the chemical formula C4H7NO5 are a significant fraction of isoprene-derived ONs, based on chamber experiments and ambient measurements from different sites around the globe. From chamber experiments we found that C4H7NO5 isomers contribute 5%-17% of all measured ONs formed during nighttime and constitute more than 40% of the measured ONs after further daytime oxidation. In ambient measurements C4H7NO5 isomers usually dominate both nighttime and daytime, implying a long residence time compared to C-5 ONs which are removed more rapidly. We propose potential nighttime sources and secondary formation pathways, and test them using a box model with an updated isoprene oxidation scheme.
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| 23. |
- Wu, R. R., et al.
(författare)
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Molecular composition and volatility of multi-generation products formed from isoprene oxidation by nitrate radical
- 2021
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Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 21:13, s. 10799-10824
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Tidskriftsartikel (refereegranskat)abstract
- Isoprene oxidation by nitrate radical (NO3) is a potentially important source of secondary organic aerosol (SOA). It is suggested that the second or later-generation products are the more substantial contributors to SOA. However, there are few studies investigating the multi-generation chemistry of isoprene-NO3 reaction, and information about the volatility of different isoprene nitrates, which is essential to evaluate their potential to form SOA and determine their atmospheric fate, is rare. In this work, we studied the reaction between isoprene and NO3 in the SAPHIR chamber (Julich) under near-atmospheric conditions. Various oxidation products were measured by a high-resolution time-offlight chemical ionization mass spectrometer using Br as the reagent ion. Most of the products detected are organic nitrates, and they are grouped into monomers (C-4 and C-5 products) and dimers (C-10 products) with 1-3 nitrate groups according to their chemical composition. Most of the observed products match expected termination products observed in previous studies, but some compounds such as monomers and dimers with three nitrogen atoms were rarely reported in the literature as gas-phase products from isoprene oxidation by NO3. Possible formation mechanisms for these compounds are proposed. The multi-generation chemistry of isoprene and NO3 is characterized by taking advantage of the time behavior of different products. In addition, the vapor pressures of diverse isoprene nitrates are calculated by different parametrization methods. An estimation of the vapor pressure is also derived from their condensation behavior. According to our results, isoprene monomers belong to intermediate-volatility or semi-volatile organic compounds and thus have little effect on SOA formation. In contrast, the dimers are expected to have low or extremely low volatility, indicating that they are potentially substantial contributors to SOA. However, the monomers constitute 80% of the total explained signals on average, while the dimers contribute less than 2 %, suggesting that the contribution of isoprene NO3 oxidation to SOA by condensation should be low under atmospheric conditions. We expect a SOA mass yield of about 5% from the wall-loss- and dilution-corrected mass concentrations, assuming that all of the isoprene dimers in the low- or extremely low-volatility organic compound (LVOC or ELVOC) range will condense completely.
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| 24. |
- Brownwood, B., et al.
(författare)
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Gas-Particle Partitioning and SOA Yields of Organonitrate Products from NO3-Initiated Oxidation of Isoprene under Varied Chemical Regimes
- 2021
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Ingår i: Acs Earth and Space Chemistry. - : American Chemical Society (ACS). - 2472-3452. ; 5:4, s. 785-800
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Tidskriftsartikel (refereegranskat)abstract
- Alkyl nitrate (AN) and secondary organic aerosol (SOA) from the reaction of nitrate radicals (NO3) with isoprene were observed in the Simulation of Atmospheric PHotochemistry In a large Reaction (SAPHIR) chamber during the NO(3)Isop campaign in August 2018. Based on 15 day-long experiments under various reaction conditions, we conclude that the reaction has a nominally unity molar AN yield (observed range 90 +/- 40%) and an SOA mass yield of OA + organic nitrate aerosol of 13-15% (with similar to 50 mu g m(-3) inorganic seed aerosol and 2-5 mu g m-3 total organic aerosol). Isoprene (5-25 ppb) and oxidant (typically similar to 100 ppb O-3 and 5-25 ppb NO2) concentrations and aerosol composition (inorganic and organic coating) were varied while remaining close to ambient conditions, producing similar AN and SOA yields under all regimes. We observe the formation of dinitrates upon oxidation of the second double bond only once the isoprene precursor is fully consumed. We determine the bulk partitioning coefficient for ANs (K-p similar to 10(-3) m(3) mu g(-1)), indicating an average volatility corresponding to a C-5 hydroxy hydroperoxy nitrate.
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| 25. |
- Casewell, Nicholas R, et al.
(författare)
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Solenodon genome reveals convergent evolution of venom in eulipotyphlan mammals.
- 2019
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 116:51, s. 25745-25755
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Tidskriftsartikel (refereegranskat)abstract
- Venom systems are key adaptations that have evolved throughout the tree of life and typically facilitate predation or defense. Despite venoms being model systems for studying a variety of evolutionary and physiological processes, many taxonomic groups remain understudied, including venomous mammals. Within the order Eulipotyphla, multiple shrew species and solenodons have oral venom systems. Despite morphological variation of their delivery systems, it remains unclear whether venom represents the ancestral state in this group or is the result of multiple independent origins. We investigated the origin and evolution of venom in eulipotyphlans by characterizing the venom system of the endangered Hispaniolan solenodon (Solenodon paradoxus). We constructed a genome to underpin proteomic identifications of solenodon venom toxins, before undertaking evolutionary analyses of those constituents, and functional assessments of the secreted venom. Our findings show that solenodon venom consists of multiple paralogous kallikrein 1 (KLK1) serine proteases, which cause hypotensive effects in vivo, and seem likely to have evolved to facilitate vertebrate prey capture. Comparative analyses provide convincing evidence that the oral venom systems of solenodons and shrews have evolved convergently, with the 4 independent origins of venom in eulipotyphlans outnumbering all other venom origins in mammals. We find that KLK1s have been independently coopted into the venom of shrews and solenodons following their divergence during the late Cretaceous, suggesting that evolutionary constraints may be acting on these genes. Consequently, our findings represent a striking example of convergent molecular evolution and demonstrate that distinct structural backgrounds can yield equivalent functions.
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