4,588 research outputs found

    Charge asymmetry measurements at the LHC

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    Measurements of the differences in angular distributions between top and anti-top quarks, referred to as charge asymmetry, in proton-proton collisions at the LHC at a centre-of-mass energy of 7TeV are presented. The data were collected by the ATLAS and CMS experiments and correspond to integrated luminosities of 0.7 fb−1 and 1.1 fb−1, respectively. To measure the charge asymmetry in the charge-symmetric initial state processes at the LHC, the difference of absolute (pseudo-)rapidities of the top and anti-top quarks is used. The asymmetry is measured inclusively and also as a function of the top-quark pair invariant mass

    Election Reform in Virginia: Deliberation and Incremental Change

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    Several key factors explain the incremental approach to election law after the 2000 presidential election. The close election in Florida spurred lawmakers in Virginia to create the Joint Subcommittee Studying Virginia\u27s Election Process and Voting Technologies. This special subcommittee was formed to learn more about the capacity of election administration. Through that process, Virginia officials concluded that the election system was fundamentally sound, though they identified a need for additional resources to increase staff, improve polling place access for disabled voters, and clean up registration rolls. A declining fiscal outlook limited budget resources and constrained the legislature from adopting the joint subcommittee\u27s modest recommendations for additional spending. Interestingly, partisan differences over the most controversial issue-recounting ballots-were overcome as a result of deliberation. The joint subcommittee\u27s study created a forum within which a leading Republican senator changed his initial preference for how to recount ballots, and his view prevailed against the wishes of the Republican majority in the House of Delegates. Thus, in the case of Virginia, the deliberative process altered the policy views of a key committee leader, who in turn affected the outcome of the legislative process during the 2002 session. The legislature continued to pass incremental changes to upgrade the electoral system during 2003

    Щоденники експедиційної роботи Григорія Дем'яна (Вступна стаття та підготовка текстів Василя Сокола)

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    The interaction between S(-II) and ferric oxides exerts a major control for the sulphur and iron cycle and in particular for the carbon and electron flow in many aquatic systems. It is regarded to be a key reaction leading ultimately to pyrite formation, the pathways still remaining unresolved. We have studied the reaction between lepidocrocite (γ-FeOOH, 21–42 mmol L−1) and dissolved S(-II) (3–9 mmol L−1) in batch experiments at pH 7 in a glove box using TEM, XRD, Mössbauer spectroscopy, and wet chemistry extraction to explore the nanocrystalline products forming at different time steps in close contact to the lepidocrocitesurface. S(0) and acid extractable Fe(II) (Fe(II)HCl) were the main products detected by wet chemistry extraction. The reaction could be divided into three steps: a rapid (<15 min) consumption of dissolved S(-II), formationof S(0) and the build-up of an Fe(II)HCl pool. Then in the absence of dissolved S(-II) concentrations of S(0) and Fe(II)HCl increased only slightly. TEM measurements revealed the occurrence of a mackinawite rim covering the lepidocrocite crystals and being separated from the lepidocrocitesurface by an interfacial magnetite layer that can be regarded as a steady state product of the interaction between lepidocrocite and mackinawite. A significant fraction of Fe(II) was formed in excess to FeS within the first 2 h. The amount of this fraction increased with decreasing ratio between dissolved S(-II) concentration and the concentration ofsurface sites, which we attributed to a kinetic decoupling of S(-II) oxidation and Fe(II) detachment from the lepidocrocitesurface. At low ratios, S(-II) seems to transfer electrons to lepidocrocite faster then stoichiometric amounts of FeS could. After 2 days Fe(II)HCl and S(0) started to decrease resulting in pyrite formation accompanied by traces of magnetite. TEM measurements indicated that mackinawite completely dissolved and precipitation of pyrite occurred dislocated from the lepidocrocitesurface. The absence of dissolved sulphide under these conditions suggest that excess Fe(II) is involved in the formationof polysulphides which are key precursors during pyrite formation. We propose that the occurrence of excess Fe(II) is a common phenomenon particularly in low sulphide – high iron environments attributing significant reactivity to ferric (hydr)oxide

    Pneumothorax spontané et emphysème pulmonaire chez les consommateurs de cannabis

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    INTRODUCTION: If pulmonary complications of tobacco smoking are well documented, those associated with cannabis use are less known. OBJECTIVES: Systematic literature review of data on pneumothorax and lung emphysema in cannabis users. DOCUMENTARY SOURCES: Medline, on the period 1980-2018 with the following keywords cannabis or marijuana and pneumothorax or emphysema, limits "title/abstract". Among 97 articles, 42 abstracts have given use to a dual reading to select 20 studies. RESULTS: Eighteen case reports (8 with SP) showed bullae in the upper lobes in combined cannabis and tobacco smokers (CS) and in the 2 cannabis only smokers (COS). The risk of SP was increased in CS, but not in COS. In patients less than 35-years old presenting with SP, the incidence of bullae on thoracic computed tomography (CT) was higher in CS than in tobacco only smokers (TOS). CT in patients with SP showed no significant difference as regards of the prevalence, location and type of emphysema between CS and TOS. Proportion of low lung density areas was higher in CS than in non-smokers (NS), but was similar in TOS and NS. CONCLUSION: These results suggest a cumulative toxic effect of tobacco and cannabis on the risk of SP and lung emphysema

    « Substances addictives » : une nouvelle série thématique

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