Measurement of the tt̄W and tt̄Z production cross sections in pp collisions at √s = 8 TeV with the ATLAS detector

The production cross sections of top-quark pairs in association with massive vector bosons have been measured using data from pp collisions at s√ = 8 TeV. The dataset corresponds to an integrated luminosity of 20.3 fb−¹ collected by the ATLAS detector in 2012 at the LHC. Final states with two, three or four leptons are considered. A fit to the data considering the tt̄W and tt̄Z processes simultaneously yields a significance of 5.0σ (4.2σ) over the background-only hypothesis for tt¯Wtt¯W (tt̄Z) production. The measured cross sections are σtt̄W = 369 + 100−91 fb and σtt̄Z = 176 + 58−52 fb. The background-only hypothesis with neither tt̄W nor tt̄Z production is excluded at 7.1σ. All measurements are consistent with next-to-leading-order calculations for the tt̄W and tt̄Z processes

Long-term exposure to air pollution and chronic kidney disease-associated mortality - results from the pooled cohort of the European multicentre ELAPSE-study

Despite the known link between air pollution and cause-specific mortality, its relation to chronic kidney disease (CKD)-associated mortality is understudied. Therefore, we investigated the association between long-term exposure to air pollution and CKD-related mortality in a large multicentre population-based European cohort. Cohort data were linked to local mortality registry data. CKD-death was defined as ICD10 codes N18-N19 or corresponding ICD9 codes. Mean annual exposure at participant's home address was determined with fine spatial resolution exposure models for nitrogen dioxide (NO 2), black carbon (BC), ozone (O 3), particulate matter ≤2.5μm (PM 2.5) and several elemental constituents of PM 2.5. Cox regression models were adjusted for age, sex, cohort, calendar year of recruitment, smoking status, marital status, employment status and neighbourhood mean income. Over a mean follow-up time of 20.4 years, 313 of 289 564 persons died from CKD. Associations were positive for PM 2.5 (hazard ratio (HR) with 95% confidence interval (CI) of 1.31 (1.03-1.66) per 5μg/m 3, BC (1.26 (1.03-1.53) per 0.5×10 - 5/m), NO 2 (1.13 (0.93-1.38) per 10μg/m 3) and inverse for O 3 (0.71 (0.54-0.93) per 10μg/m 3). Results were robust to further covariate adjustment. Exclusion of the largest sub-cohort contributing 226 cases, led to null associations. Among the elemental constituents, Cu, Fe, K, Ni, S and Zn, representing different sources including traffic, biomass and oil burning and secondary pollutants, were associated with CKD-related mortality. In conclusion, our results suggest an association between air pollution from different sources and CKD-related mortality

ODL and access to higher education: the experiences of the University of Botswana

This interpretive qualitative study investigated why open and distance learning (ODL) within some dual mode universities seemingly failed to achieve high participation rates, compared to the face-to-face mode of delivery in the same institution. Its scope was the Botswana higher education sector. The University of Botswana (UB), the only public dual mode university in Botswana, was closely studied. The main question explored why some dual mode universities in southern Africa enrolled lower figures through ODL than the face-to-face mode of delivery, though ODL had more potential to increase access substantially than the face-to-face mode. Data were collected through semi-structured interviews and document analysis. Purposive selection drew participants from UB, the Tertiary Education Council (TEC) and the Ministry of Education and Skills Development (MOESD), based on their experience in education planning, policy formulation and ODL delivery. Data were analysed through qualitative content analysis. The study confirmed internal and external attitudes that create equivalency challenges and impede ODL growth in dual mode universities, resulting in its limited contribution to participation. It established that dual mode institutions need relevant policies, structures and enhanced resources for ODL, in order to significantly increase participation. The study consequently advocates thorough planning for a dual mode setup, commitment of resources, monitored implementation and appropriately trained staff