Liquid-based cytology for primary cervical cancer screening: a multi-centre study

The aim of this six-centre, split-sample study was to compare ThinPrep fluid-based cytology to the conventional Papanicolaou smear. Six cytopathology laboratories and 35 gynaecologists participated. 5428 patients met the inclusion criteria (age > 18 years old, intact cervix, informed consent). Each cervical sample was used first to prepare a conventional Pap smear, then the sampling device was rinsed into a PreservCyt vial, and a ThinPrep slide was made. Screening of slide pairs was blinded (n = 5428). All non-negative concordant cases (n = 101), all non-concordant cases (n = 206), and a 5% random sample of concordant negative cases (n = 272) underwent review by one independent pathologist then by the panel of 6 investigators. Initial (blinded) screening results for ThinPrep and conventional smears were correlated. Initial diagnoses were correlated with consensus cytological diagnoses. Differences in disease detection were evaluated using McNemar's test. On initial screening, 29% more ASCUS cases and 39% more low-grade squamous intraepithelial lesions (LSIL) and more severe lesions (LSIL+) were detected on the ThinPrep slides than on the conventional smears (P = 0.001), including 50% more LSIL and 18% more high-grade SIL (HSIL). The ASCUS:SIL ratio was lower for the ThinPrep method (115:132 = 0.87:1) than for the conventional smear method (89:94 = 0.95:1). The same trend was observed for the ASCUS/AGUS:LSIL ratio. Independent and consensus review confirmed 145 LSIL+ diagnoses; of these, 18% more had been detected initially on the ThinPrep slides than on the conventional smears (P = 0.041). The ThinPrep Pap Test is more accurate than the conventional Pap test and has the potential to optimize the effectiveness of primary cervical cancer screening. © 2001 Cancer Research Campaign http://www.bjcancer.co

Epidemiologie de la tuberculose pleuro-pulmonaire : cas de tuberculose depistes a Troyes en 1977 chez l'adulte

Available from INIST (FR), Document Supply Service, under shelf-number : TM 834 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEFRFranc

Une étude numérique du rôle de la couche d'oxydes dans l'amorçage de fissures de fatigue à moyenne température

les pièces industrielles sollicitées en fatigue sont souvent recouvertes d'oxydes ou revêtues. L'objectif de ce travail est d'évaluer l'impact que peut avoir cette couche mince à la surface du métal d'une part sur les déformations et le relief dû aux bandes de glissement et d'autre part sur l'amorçage des fissures de fatigue. La couche mince est supposée élastique fragile. Les modèles proposés sont basés sur des calculs par éléments finis et des critères énergétiques de fissuration. Ils sont confrontés à des observations et des résultats d'essais de la littérature

Experimentally based modelling of cyclically induced softening in a martensitic steel at high temperature

International audienc

Ultrasonic measurement of anisotropy and temperature dependence of elastic parameters by a dry coupling method applied to a 6061-T6 alloy

International audienceA pulse-echo ultrasonic method is presented to measure elastic parameter variations during thermal loading with high accuracy. Using a dry coupling configuration dedicated to high temperature investigation, this technique has been applied on 6061-T6 aluminium samples up to 220 °C. Experimental settings are described to assess the measurement reproducibility estimated at a value of 0.2%. Consequently, the anisotropy of this aluminium between the rolling direction and two orthogonal axes has been clearly detected and also measured versus temperature. As regards the temperature dependence of these elastic parameters, these results are compared with the estimations of the Young's modulus obtained during mechanical tests in conditions of low cycle fatigue (LCF). The same linear variation versus temperature is found but with a shift of 7 GPa. This difference has been classically attributed to systematic experimental error sources and to the distinction existing between dynamic and static elastic modulus

Analysis of the hysteresis loops of a martensitic steel, part I., study of the influence of strain amplitude and temperature under pure fatigue loadings using an enhanced stress partitioning method

International audienceIn order to identify the microstructural mechanisms leading to the softening effect usually presented by martensitic steels under cyclic loadings (with or without hold times), a study of the cyclic stress partition is presented. As the usual stress partitioning methods were found to be inadequate in the present case, a new method based both on Cottrell's method and on the Statistical Process Control principles, is proposed. This new method is used to distinguish between the kinematic, the isotropic and the viscous parts of the cyclic stress. The evolutions of these different stresses are evaluated for several strain amplitudes and temperatures under pure fatigue loading in this first part. It is shown that the softening effect is mainly due to a decrease of the backstress: the higher the strain amplitude, the stronger and the faster the softening effect. The isotropic stress is found to be independent of the strain amplitude, but increases when the temperature decreases. Whereas the viscous stress represents a large part of the total stress at 823 K, it becomes almost negligible below 673 K. These results are finally linked to the microstructural coarsening previously observed and modelled. Therefore, the decrease of the kinematic stress can be related to grain size effect

Cyclic softening of martensitic steels at high temperature—Experiments and physically based modelling

International audienc

Analysis of the hysteresis loops of a martensitic steel. Part I and Part II

International audienceThe second part of this work is devoted to the study of holding time effects on the cyclic plastic behaviour of a martensitic steel tested at 823 K. Both relaxation and creep holding times of various durations were applied. The enhanced stress partitioning method presented in the first part [B. Fournier, M. Sauzay, C. Cae's, M. Mottot, Mater. Sci. Eng., submitted for publication] is used to evaluate the kinematic, isotropic and viscous parts of the cyclic stress. The bulk Young's modulus is found to vary significantly during cycling for creep-fatigue tests, which might be correlated to specific environmental interaction. The viscous stress measured at the end of the holding period tends to vanish as the holding time increases. The introduction of creep holding times enabled higher viscoplastic strains per cycle to be reached and allowed a larger range of strain rates to be studied. In all the cases tested, the observed softening effect is mainly due to the kinematic stress decrease. Nevertheless, even though the kinematic stress is always found to decrease with increasing accumulated viscoplastic strain, the initial magnitude of the creep-fatigue kinematic stress (measured at the end of the first holding period) can be either higher or lower than that of the corresponding pure-fatigue test. These effects of the holding period on the kinematic stress value can be related to the viscoplastic strain rate (and to the nature of the holding time: creep or relaxation). This dependency presents a maximum at intermediate strain rate, suggesting that two competing microstructural mechanisms control the magnitude of the kinematic stress. The enhanced stress partitioning method also enables the activation volume of both the creep and fatigue deformation mechanisms to be evaluated. The observed values are compared to those found in the literatur

Creep-fatigue interactions in a 9 Pct Cr-1 Pct Mo martensitic steel, part I. Mechanical test results

International audienceCreep-fatigue (CF) tests are carried out on a modified 9 pct Cr-1 pct Mo (P91) steel at 550 °C. These CF tests are strain controlled during the cyclic part of the stress-strain hysteresis loop and then load controlled when the stress is maintained at its maximum value, to produce a prescribed value of the creep strain before cyclic deformation is reversed under strain-controlled conditions. The observed cyclic softening implies that the applied creep stress continuously decreases with the number of cycles. However, the minimum creep rates measured at the end of the holding periods do not decrease when the applied stress decreases. The minimum creep rates measured at the end of these tests can be hundreds of times faster than those observed for the as-received material. This acceleration of creep rates can be to the microstructural coarsening and to the decrease of the dislocation density observed after fatigue and CF loadings. Cyclic creep tests consisting of very long holding periods interrupted by unloading/reloading are also carried out. These results suggest that cyclic loadings affect the creep lifetime and flow behavior only if a plastic strain is applied during cycling. Creep tests carried out on a material cyclically prestrained and fatigue tests carried out on a material previously deformed in creep confirm that the deterioration of the mechanical properties is much faster in fatigue and CF compared to creep