30 research outputs found

    Black-carbon absorption enhancement in the atmosphere determined by particle mixing state

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    Atmospheric black carbon makes an important but poorly quantified contribution to the warming of the global atmosphere. Laboratory and modelling studies have shown that the addition of non-black-carbon materials to black-carbon particles may enhance the particles’ light absorption by 50 to 60% by refracting and reflecting light. Real-world experimental evidence for this ‘lensing’ effect is scant and conflicting, showing that absorption enhancements can be less than 5% or as large as 140%. Here we present simultaneous quantifications of the composition and optical properties of individual atmospheric black-carbon particles. We show that particles with a mass ratio of non-black carbon to black carbon of less than 1.5, which is typical of fresh traffic sources, are best represented as having no absorption enhancement. In contrast, black-carbon particles with a ratio greater than 3, which is typical of biomass-burning emissions, are best described assuming optical lensing leading to an absorption enhancement. We introduce a generalized hybrid model approach for estimating scattering and absorption enhancements based on laboratory and atmospheric observations. We conclude that the occurrence of the absorption enhancement of black-carbon particles is determined by the particles’ mass ratio of non-black carbon to black carbon

    Physics of the HL-LHC, and Perspectives at the HE-LHC

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    The Forward Physics Facility at the High-Luminosity LHC

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    Standard Model Physics at the HL-LHC and HE-LHC

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    The successful operation of the Large Hadron Collider (LHC) and the excellent performance of the ATLAS, CMS, LHCb and ALICE detectors in Run-1 and Run-2 with pppp collisions at center-of-mass energies of 7, 8 and 13 TeV as well as the giant leap in precision calculations and modeling of fundamental interactions at hadron colliders have allowed an extraordinary breadth of physics studies including precision measurements of a variety physics processes. The LHC results have so far confirmed the validity of the Standard Model of particle physics up to unprecedented energy scales and with great precision in the sectors of strong and electroweak interactions as well as flavour physics, for instance in top quark physics. The upgrade of the LHC to a High Luminosity phase (HL-LHC) at 14 TeV center-of-mass energy with 3 ab−1^{-1} of integrated luminosity will probe the Standard Model with even greater precision and will extend the sensitivity to possible anomalies in the Standard Model, thanks to a ten-fold larger data set, upgraded detectors and expected improvements in the theoretical understanding. This document summarises the physics reach of the HL-LHC in the realm of strong and electroweak interactions and top quark physics, and provides a glimpse of the potential of a possible further upgrade of the LHC to a 27 TeV pppp collider, the High-Energy LHC (HE-LHC), assumed to accumulate an integrated luminosity of 15 ab−1^{-1}

    Health-related articles on Syria before and after the start of armed conflict: a scoping review for The Lancet-American University of Beirut Commission on Syria

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    Introduction Armed conflict may influence the size and scope of research in Arab countries. We aimed to assess the impact of the 2011 Syrian conflict on health articles about Syria published in indexed journals. Methods We conducted a scoping review on Syrian health-related articles using seven electronic databases. We included clinical, biomedical, public health, or health system topics published between 1991 and 2017. We excluded animal studies and studies conducted on Syrian refugees. We used descriptive and social network analyses to assess the differences in rates, types, topics of articles, and authorship before and after 2011, the start of the Syrian conflict. Results Of 1138 articles, 826 (72.6%) were published after 2011. Articles published after 2011 were less likely to be primary research; had a greater proportion reporting on mental health (4.6% vs. 10.0%), accidents and injuries (2.3% vs. 18.8%), and conflict and health (1.7% vs. 7.8%) (all p < 0.05); and a lower proportion reporting on child and maternal health (8.1 to 3.6%, p = 0.019). The proportion of research articles reporting no funding increased from 1.1 to 14.6% (p < 0.01). While international collaborations increased over time, the number of articles with no authors affiliated to Syrian institutions overtook those with at least one author affiliation to a Syrian institution for the first time in 2015. Conclusion To our knowledge, this is the first study to examine the impact of armed conflict on health scholarship in Syria. The Syrian conflict was associated with a change in the rates, types, and topics of the health-related articles, and authors’ affiliations. Our findings have implications for the prioritization of research funding, development of inclusive research collaborations, and promoting the ethics of conducting research in complex humanitarian settings
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