Factors associated with false-negative cervical cytopathological results

Purpose: to evaluate whether factors related to the adequacy of the sample, cell pattern and cytomorphological criteria are associated with false-negative (FN) results of cervical cytopathology during routine examinations. Methods: this is a case-control study in which the study group included 100 cytopathologic smears with FN results detected during systematic internal quality control consisting of 100% rapid review. For each FN result detected, two smears with a true-positive diagnosis were identified by the same cytotechnician and these constituted the control group, making a total sample size of 300 smears. The variables were established in accordance with the criteria defined for the analysis of sample adequacy, cell pattern and cytomorphological analyzed criteria. The results were evaluated using bivariate analysis and logistic regression with stepwise variable selection criteria expressed in OR (95%). Results: the number of atypical cells, the appearance of nuclear chromatin, and the distribution and presentation of atypical cells in the smear were the variables that showed the greatest risk for FN results with OR of 9.6, 4.2, 4.4, and 3.6, respectively. Inflammatory processes and the presence of blood in the smear were also identified as variables that influence the risk of FN results. Conclusions: the majority of the factors associated with FN results are dependent on the conditions and techniques of sample collection, since in the majority of cases, the lesion may not be adequately represented in the smear. Confounding factors such as blood and inflammatory processes may also impair analysis. With respect to cytomorphological alterations, thin chromatin strand was the variable that indicated the greatest risk of FN results.Verificar se, no escrutínio de rotina, fatores relacionados com a adequabilidade da amostra, padrão celular e critérios citomorfológicos estão associados a resultados falso-negativos (FN) dos exames citopatológicos. Métodos: trata-se de um estudo caso-controle, no qual o grupo de casos incluiu 100 esfregaços citopatológicos com um resultado FN que foi detectado pela sistemática de controle interno da qualidade com revisão rápida de 100%. Para cada resultado FN detectado foram identifi cados,pelo mesmo citotécnico, dois esfregaços com um diagnóstico verdadeiro-positivo e este grupo foi considerado controle, totalizando uma casuística de 300 esfregaços. As variáveis analisadas foram estabelecidas de acordo com os critérios defi nidos para a análise da adequabilidade da amostra, padrão celular e critérios citomorfológicos. Os resultados foram avaliados por análise bivariada e regressão logística com critério de seleção de variáveis stepwise e expressos em OR (95%). Resultados: o número de células atípicas, aspecto da cromatina nuclear, distribuição e apresentação de células atípicas no esfregaço apresentaram risco maior para resultados FN, com OR de 9,6; 4,2; 4,4 e 3,6, respectivamente. Processo infl amatório e presença de sangue no esfregaço mostraram também risco para os resultados FN. Conclusões: a maioria dos fatores associados à liberação de um resultadoFN é dependente das condições e técnicas de coleta de material, pois, em grande parte, a lesão pode não estar adequadamente representada no esfregaço, e também fatores obscurecedores como sangue e processo infl amatório podem prejudicar a análise. Quanto às alterações citomorfológicas, cromatina fi na foi a característica que apresentou maior risco para resultados FN288479485To evaluate whether factors related to the adequacy of the sample, cell pattern and cytomorphological criteria are associated with false-negative (FN) results of cervical cytopathology during routine examinations. Methods: this is a case-control study in which the study group included 100 cytopathologic smears with FN results detected during systematic internal quality control consisting of 100% rapid review. For each FN result detected, two smears with a true-positive diagnosis were identified by the same cytotechnician and these constituted the control group, making a total sample size of 300 smears. The variables were established in accordance with the criteria defined for the analysis of sample adequacy, cell pattern and cytomorphological analyzed criteria. The results were evaluated using bivariate analysis and logistic regression with stepwise variable selection criteria expressed in OR (95%). Results: the number of atypical cells, the appearance of nuclear chromatin, and the distribution and presentation of atypical cells in the smear were the variables that showed the greatest risk for FN results with OR of 9.6, 4.2, 4.4, and 3.6, respectively. Inflammatory processes and the presence of blood in the smear were also identified as variables that influence the risk of FN results. Conclusions: the majority of the factors associated with FN results are dependent on the conditions and techniques of sample collection, since in the majority of cases, the lesion may not be adequately represented in the smear. Confounding factors such as blood and inflammatory processes may also impair analysis. With respect to cytomorphological alterations, thin chromatin strand was the variable that indicated the greatest risk of FN result

Measurement of the partial widths of the Z into up- and down-type quarks

Using the entire OPAL LEP1 on-peak Z hadronic decay sample, Z -> qbarq gamma decays were selected by tagging hadronic final states with isolated photon candidates in the electromagnetic calorimeter. Combining the measured rates of Z -> qbarq gamma decays with the total rate of hadronic Z decays permits the simultaneous determination of the widths of the Z into up- and down-type quarks. The values obtained, with total errors, were Gamma u = 300 ^{+19}_{-18} MeV and Gamma d = 381 ^{+12}_{-12} MeV. The results are in good agreement with the Standard Model expectation.Comment: 22 pages, 5 figures, Submitted to Phys. Letts.

Search for R-Parity Violating Decays of Scalar Fermions at LEP

A search for pair-produced scalar fermions under the assumption that R-parity is not conserved has been performed using data collected with the OPAL detector at LEP. The data samples analysed correspond to an integrated luminosity of about 610 pb-1 collected at centre-of-mass energies of sqrt(s) 189-209 GeV. An important consequence of R-parity violation is that the lightest supersymmetric particle is expected to be unstable. Searches of R-parity violating decays of charged sleptons, sneutrinos and squarks have been performed under the assumptions that the lightest supersymmetric particle decays promptly and that only one of the R-parity violating couplings is dominant for each of the decay modes considered. Such processes would yield final states consisting of leptons, jets, or both with or without missing energy. No significant single-like excess of events has been observed with respect to the Standard Model expectations. Limits on the production cross- section of scalar fermions in R-parity violating scenarios are obtained. Constraints on the supersymmetric particle masses are also presented in an R-parity violating framework analogous to the Constrained Minimal Supersymmetric Standard Model.Comment: 51 pages, 24 figures, Submitted to Eur. Phys. J.

Measurement of Rb in e+e- Collisions at 182 - 209 GeV

Measurements of Rb, the ratio of the bbbar cross-section to the qqbar cross- section in e+e- collisions, are presented. The data were collected by the OPAL experiment at LEP at centre-of-mass energies between 182 GeV and 209 GeV. Lepton, lifetime and event shape information is used to tag events containing b quarks with high efficiency. The data are compatible with the Standard Model expectation. The mean ratio of the eight measurements reported here to the Standard Model prediction is 1.055+-0.031+-0.037, where the first error is statistical and the second systematic.Comment: 21 pages, 5 figures, Submitted to Phys. Letts

Search for the standard model Higgs boson decaying into two photons in pp collisions at sqrt(s)=7 TeV

A search for a Higgs boson decaying into two photons is described. The analysis is performed using a dataset recorded by the CMS experiment at the LHC from pp collisions at a centre-of-mass energy of 7 TeV, which corresponds to an integrated luminosity of 4.8 inverse femtobarns. Limits are set on the cross section of the standard model Higgs boson decaying to two photons. The expected exclusion limit at 95% confidence level is between 1.4 and 2.4 times the standard model cross section in the mass range between 110 and 150 GeV. The analysis of the data excludes, at 95% confidence level, the standard model Higgs boson decaying into two photons in the mass range 128 to 132 GeV. The largest excess of events above the expected standard model background is observed for a Higgs boson mass hypothesis of 124 GeV with a local significance of 3.1 sigma. The global significance of observing an excess with a local significance greater than 3.1 sigma anywhere in the search range 110-150 GeV is estimated to be 1.8 sigma. More data are required to ascertain the origin of this excess.Comment: Submitted to Physics Letters

Measurement of isolated photon production in pp and PbPb collisions at sqrt(sNN) = 2.76 TeV

Isolated photon production is measured in proton-proton and lead-lead collisions at nucleon-nucleon centre-of-mass energies of 2.76 TeV in the pseudorapidity range |eta|<1.44 and transverse energies ET between 20 and 80 GeV with the CMS detector at the LHC. The measured ET spectra are found to be in good agreement with next-to-leading-order perturbative QCD predictions. The ratio of PbPb to pp isolated photon ET-differential yields, scaled by the number of incoherent nucleon-nucleon collisions, is consistent with unity for all PbPb reaction centralities.Comment: Submitted to Physics Letters