A description is provided of the software algorithms developed for the CMS tracker both for reconstructing charged-particle trajectories in proton-proton interactions and for using the resulting tracks to estimate the positions of the LHC luminous region and individual primary-interaction vertices. Despite the very hostile environment at the LHC, the performance obtained with these algorithms is found to be excellent. For tt events under typical 2011 pileup conditions, the average trackreconstruction efficiency for promptly-produced charged particles with transverse momenta of p T > 0.9 GeV is 94% for pseudorapidities of |η| < 0.9 and 85% for 0.9 < |η| < 2.5. The inefficiency is caused mainly by hadrons that undergo nuclear interactions in the tracker material. For isolated muons, the corresponding efficiencies are essentially 100%. For isolated muons of p T = 100 GeV emitted at |η| < 1.4, the resolutions are approximately 2.8% in p T , and respectively, 10 µm and 30 µm in the transverse and longitudinal impact parameters. The position resolution achieved for reconstructed primary vertices that correspond to interesting pp collisions is 10-12 µm in each of the three spatial dimensions. The tracking and vertexing software is fast and flexible, and easily adaptable to other functions, such as fast tracking for the trigger, or dedicated tracking for electrons that takes into account bremsstrahlung.

Sleep disturbance and insomnia are two separate but overlapping constructs and should be differentiated. Sleep disturbance is very common in the elderly and may be due to physiological changes with ageing. In contrast, those with a concommitant complaint of insomnia have impaired physical and mental health and may merit more medical attention.

Recent studies suggest that reductions in circulating endothelial progenitor cells (EPCs) may contribute to the development of atherosclerosis. However, whether reduced circulating EPCs contribute to cerebrovascular disease remains undefined. We tested the hypothesis that reduced circulating EPCs was associated with an increased burden of carotid atherosclerosis. The level of circulating CD34 þ /KDR þ EPCs and the extent of carotid atherosclerosis were determined in 30 patients with a history of atherothrombotic ischaemic stroke and 30 age-and sex-matched controls (mean age: 6372 years; 63% men). Stroke patients, compared with controls, had significantly higher carotid mean maximum intima-media thickness (mmIMT) (1.0870.05 versus 0.9070.02 mm, P ¼ 0.002), prevalence of carotid plaque (60.0 versus 23.3%, P ¼ 0.004) and a lower number of circulating CD34 þ /KDR þ EPCs (235.7745.5 versus 400.4756.8 cells/ll, P ¼ 0.027). The circulating CD34 þ /KDR þ EPC count correlated negatively with carotid mmIMT (r ¼ À0.50, Po0.001), and was an independent risk factor for increased carotid mmIMT41 mm (odds ratio (OR): 7.71; 95% confidence interval (CI): 1.62-36.74, P ¼ 0.010) and the presence of carotid plaque (OR: 7.04; 95% CI: 1.95-25.43, P ¼ 0.003). Furthermore, stroke patients with low (o25th percentile of controls) as compared to those with normal CD34 þ /KDR þ EPC count had a significantly greater carotid mmIMT (1.217 0.07 versus 0.9370.05 mm, P ¼ 0.005) and a significantly higher prevalence of carotid plaque (87.5% versus 28.6%; P ¼ 0.001). Our observations suggested that reduced circulating EPC may contribute to the progression of carotid atherosclerosis. Circulating EPC count may provide a novel marker for the burden of carotid atherosclerosis.

The inclusive cross section for top-quark pair production measured by the CMS experiment in proton-proton collisions at a center-of-mass energy of 7 TeV is compared to the QCD prediction at next-to-next-to-leading order with various parton distribution functions to determine the top-quark pole mass, m pole t , or the strong coupling constant, α S . With the parton distribution function set NNPDF2.3, a pole mass of 176.7 +3.0 −2.8 GeV is obtained when constraining α S at the scale of the Z boson mass, m Z , to the current world average. Alternatively, by constraining m pole t to the latest average from direct mass measurements, a value of α S (m Z ) = 0.1151 +0.0028 −0.0027 is extracted. This is the first determination of α S using events from top-quark production.