1,775 research outputs found
Measurement of the ttbar production cross section in the fully hadronic decay channel in pp collisions at 7 TeV
The first measurement of the top quark pair production cross section in the
fully hadronic channel at a center-of-mass energy of TeV is
presented. The measurement has been performed using an integrated luminosity of
1.09 fb, collected with the CMS detector. The reconstruction of the
candidates is performed after a cut-based event selection using a
kinematic fit. A data-driven technique is used to estimate the dominant
background from QCD multijet production. The cross section is determined from a
fit to the top quark mass. The cross section measurement yields pb. This result is
consistent with an independent measurement in the same channel, with the
measurements in other decay channels and with the Standard Model predictions.Comment: Presented at the 2011 Hadron Collider Physics symposium (HCP-2011),
Paris, France, November 14-18 2011, 3 pages, 3 figure
Measurements of the top quark pair production cross section at 7TeV
We present several measurements of the cross section for the production of top quark pairs in proton-proton collisions at the LHC at a centre-of-mass energy of 7TeV. We use data collected with the CMS experiment during the year 2010, and amounting to a total integrated luminosity of 36 pb−1. Measurements are presented in the lepton+jets final state, where events are selected which contain
exactly one isolated, highly energetic muon or electron, and at least four jets. In addition, the di-lepton final state, which consists of two leptons, at least two jets, and
significant missing transverse energy is explored. We use b-jet identification in order to increase the purity of the selection. Important backgrounds are estimated using
data-driven techniques, and systematic uncertainties are estimated. The results are compared with theory predictions
Main electroweak physics results from CMS and ATLAS experiments
The latest electroweak results from CMS and ATLAS experiments, based on pp collision data taken at 7 and 8TeV, are presented. In particular precise measurements of the inclusive and differential cross-sections for W and Z boson production, and for multi-boson production are shown
Deep-inelastic and quasielastic electron scattering from nuclei
We perform a combined analysis of inclusive electron scattering data from
nuclei in the deep-inelastic and quasielastic scattering regions, using
Monte Carlo analysis methods and the nuclear weak binding approximation to
establish the range over which the data can be described within the same
theoretical framework. Comparison with quasielastic He cross sections from
SLAC and Jefferson Lab suggests that most features of the data
can be reasonably well described in the impulse approximation with finite-
nuclear smearing functions for momentum transfers GeV. For
the DIS region, we analyze the recent He to deuterium cross section ratio
from the Jefferson Lab E03-103 experiment to explore the possible isospin
dependence of the nuclear effects. We discuss the implications of this for the
MARATHON experiment at Jefferson Lab, and outline how a Bayesian analysis of
He, H and deuterium data can robustly determine the free neutron
structure function.Comment: 45 pages, 14 figure
Mothers and Premature Infants’ Emotional Interactions in a Neonatal Infant Care Unit: Case Studies
The aim of this study was to describe the ways premature infants and their mothers emotionally interact in the first weeks of their lives. In order to understand the intersubjective dyadic interaction between mother and premature infant, a qualitative and descriptive approach to research has been adopted. Four dyads comprised of primiparae women and their newly-born premature infants took part in the study. The babies were born prematurely after 28 to 35 weeks of gestation and admitted to the neonatal intensive care unit (NICU). Data was collected filming the first dyadic interaction with infant in the mother’s arms, lasting between 15 to 30 minutes. After that first registry, dyadic behaviors between mother and baby were described and categorized following the intersubjective categories suggested by Fiamenghi (1999) and Fiamenghi et al. (2010). Results showed that dyads display positive emotions, with infants’ behaviors falling into the categories of negotiation, interaction and emotional curiosity; as well as a low frequency of negative behaviors. The outcome of this research reinforces the need to adopt a humanizing approach to prematurely born infants and their mothers in NICU, as well as training and awareness of the whole multidisciplinary team that deals with them
Using remote substituents to control solution structure and anion binding in lanthanide complexes.
A study of the anion-binding properties of three structurally related lanthanide complexes, which all contain chemically identical anion-binding motifs, has revealed dramatic differences in their anion affinity. These arise as a consequence of changes in the substitution pattern on the periphery of the molecule, at a substantial distance from the binding pocket. Herein, we explore these remote substituent effects and explain the observed behaviour through discussion of the way in which remote substituents can influence and control the global structure of a molecule through their demands upon conformational space. Peripheral modifications to a binuclear lanthanide motif derived from α,α′-bis(DO3 Ayl)-m-xylene are shown to result in dramatic changes to the binding constant for isophthalate. In this system, the parent compound displays considerable conformational flexibility, yet can be assumed to bind to isophthalate through a well-defined conformer. Addition of steric bulk remote from the binding site restricts conformational mobility, giving rise to an increase in binding constant on entropic grounds as long as the ideal binding conformation is not excluded from the available range of conformers
Lanthanide Complexes that Respond to Changes in Cyanide Concentration in Water
Cyanide ions are shown to interact with lanthanide complexes of phenacylDO3A derivatives in aqueous solution, giving rise to changes in the luminescence and NMR spectra. These changes are the consequence of cyanohydrin formation, which is favored by the coordination of the phenacyl carbonyl group to the lanthanide center. These complexes display minimal affinity for fluoride and can detect cyanide at concentrations less than 1 μm. By contrast, lanthanide complexes with DOTAM derivatives display no affinity for cyanide in water, but respond to changes in fluoride concentration
Personal and Household Hygiene, Environmental Contamination, and Health in Undergraduate Residence Halls in New York City, 2011
Background: While several studies have documented the importance of hand washing in the university setting, the added role of environmental hygiene remains poorly understood. The purpose of this study was to characterize the personal and environmental hygiene habits of college students, define the determinants of hygiene in this population, and assess the relationship between reported hygiene behaviors, environmental contamination, and health status. Methods: 501 undergraduate students completed a previously validated survey assessing baseline demographics, hygiene habits, determinants of hygiene, and health status. Sixty survey respondents had microbiological samples taken from eight standardized surfaces in their dormitory environment. Bacterial contamination was assessed using standard quantitative bacterial culture techniques. Additional culturing for coagulase-positive Staphylococcus and coliforms was performed using selective agar. Results: While the vast majority of study participants (n = 461, 92%) believed that hand washing was important for infection prevention, there was a large amount of variation in reported personal hygiene practices. More women than men reported consistent hand washing before preparing food (p = .002) and after using the toilet (p = .001). Environmental hygiene showed similar variability although 73.3% (n = 367) of subjects reported dormitory cleaning at least once per month. Contamination of certain surfaces was common, with at least one third of all bookshelves, desks, refrigerator handles, toilet handles, and bathroom door handles positive for <10 CFU of bacteria per 4 cm2 area. Coagulase-positive Staphylococcus was detected in three participants' rooms (5%) and coliforms were present in six students' rooms (10%). Surface contamination with any bacteria did not vary by frequency of cleaning or frequency of illness (p<.05). Conclusions: Our results suggest that surface contamination, while prevalent, is unrelated to reported hygiene or health in the university setting. Further research into environmental reservoirs of infectious diseases may delineate whether surface decontamination is an effective target of hygiene interventions in this population
Using Remote Substituents to Control Solution Structure and Anion Binding in Lanthanide Complexes
A study of the anion-binding properties of three structurally related lanthanide complexes, which all contain chemically identical anion-binding motifs, has revealed dramatic differences in their anion affinity. These arise as a consequence of changes in the substitution pattern on the periphery of the molecule, at a substantial distance from the binding pocket. Herein, we explore these remote substituent effects and explain the observed behaviour through discussion of the way in which remote substituents can influence and control the global structure of a molecule through their demands upon conformational space. Peripheral modifications to a binuclear lanthanide motif derived from α,α′-bis(DO3 Ayl)-m-xylene are shown to result in dramatic changes to the binding constant for isophthalate. In this system, the parent compound displays considerable conformational flexibility, yet can be assumed to bind to isophthalate through a well-defined conformer. Addition of steric bulk remote from the binding site restricts conformational mobility, giving rise to an increase in binding constant on entropic grounds as long as the ideal binding conformation is not excluded from the available range of conformers
Measurements of branching fraction ratios and CP-asymmetries in suppressed B^- -> D(-> K^+ pi^-)K^- and B^- -> D(-> K^+ pi^-)pi^- decays
We report the first reconstruction in hadron collisions of the suppressed
decays B^- -> D(-> K^+ pi^-)K^- and B^- -> D(-> K^+ pi^-)pi^-, sensitive to the
CKM phase gamma, using data from 7 fb^-1 of integrated luminosity collected by
the CDF II detector at the Tevatron collider. We reconstruct a signal for the
B^- -> D(-> K^+ pi^-)K^- suppressed mode with a significance of 3.2 standard
deviations, and measure the ratios of the suppressed to favored branching
fractions R(K) = [22.0 \pm 8.6(stat)\pm 2.6(syst)]\times 10^-3, R^+(K) =
[42.6\pm 13.7(stat)\pm 2.8(syst)]\times 10^-3, R^-(K)= [3.8\pm 10.3(stat)\pm
2.7(syst]\times 10^-3, as well as the direct CP-violating asymmetry A(K) =
-0.82\pm 0.44(stat)\pm 0.09(syst) of this mode. Corresponding quantities for
B^- -> D(-> K^+ pi^-)pi^- decay are also reported.Comment: 8 pages, 1 figure, accepted by Phys.Rev.D Rapid Communications for
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