The Role Of Secondary Vaccine Failure In Measles outbreaks

ABSTRAK An outbreak of measles in 1985-1986 in a community where measles vaccine trials had been carried out from 1974-1976 allowed the assessment of the role of secondaryvaccine failures in previously immunized children. A total of 188 children from the vaccine trial were followed. Of these, 175 seroconverted initially while 13 (6 percent) required re-immunization (primary failure). A total of 13 cases of measles, eight of which were laboratory and/or physician-confirmed, were reported in this cohort. Of these, nine cases occurred in the 175 subjects who had hemagglutination inhibition (HI) and neutralizing antibody responses following the initial immunization. These nine cases represent secondary vaccine failures. An additional four cases occured in the 13 subjects with primary vaccine failure. We conclude that secondary vaccine failures occur and that while primary failures account for most cases, secondary vaccine failures contribute to the occurrence of measles cases in an epidemic. A booster dose of measles vaccine may be necessary to reduce susceptibility to a sufficiently low level to allow the goal of measles elimination to be achieved. Key word : vaccin

Influence of roughness on ZDDP tribofilm formation in boundary lubricated fretting

Influence of initial surface topography on tribofilm formation in ZDDP lubricated contact was analysed. A small displacement fretting tests with sinusoidal motion were carried out in classical sphere/plane configuration. A range of surfaces with different initial roughness were prepared by milling and grinding processes. Tests were carried out using variable displacement method where amplitude of imposed displacement was gradually increased after every 1000 cycles from 2 to 30 µm. The surfaces after tribological tests were measured by interferometric profiler. Main findings confirm that initial roughness has a significant influence on antiwear tribofilm formation in boundary lubricated contact. Tribofilm form faster and require less energy to activate in case of rough surface obtained by milling process than in case of smooth grinded surface. However, in contact lubricated by ZDDP additive a significant transfer of material occurred from plane to sphere specimen

The metrology of ground concrete surfaces morphology with 3D laser scanner

This paper is devoted to machining of concrete by grinding and the metrology of its surface morphologies. The surface morphology is still open problem from metrological as well as mathematical morphology points of views. In order to understand better abrasive process the raw morphologic state is compared with the ground concrete surfaces. The most significant results are presented in the form of profiles, 3D isometric views and isotropy analysis. Several 3D surface roughness parameters were calculated

Sclero-topometry metrology in valorisation of waste oil for micro-machining of ductile cast iron

During the time, the specific characteristics and the efficient life time of oil progressively decrease, due to complex pollution, ultimately making the oil unsuitable for the initial applications. The strategy to regenerate and to valorise waste oils is investigated using improved combinations of sclerometric and topometric tests on ductile nodular cast iron. Tribo-abrasive tests are performed in critical conditions, with base oil, waste oil and regenerated oil, of similar viscosities in order to discriminate their interfacial performances. The forms of the scratch traces indicate wear resistance and tendency to elasto-plastic deformation. The mechanisms of deformation and frictional behaviours were evaluated using optical and Scanning Electron Microscopy and measured for various tribological conditions with tactile and optical profilometry. The Energy Dispersive X ray Spectroscopy completes the chemical superficial distribution of pertinent elements. The surface topography metrology is used to characterize the scratch profiles and to determine the volume of the displaced and removed material, as well as maximum pit height. The originality of this paper is that it is a unique approach specifically devoted to transformer oil concerning tribological conditions

Prediction of Microfinishing Effects with the Use of Abrasive Films Utilizing Data Characterizing Their Surface Topography

The publication describes the methodology and results of the studies on stereometric characteristics of the diamond surface of microfinishing films. This methodology is used in different treatments of precise finishing of very high smoothness and accuracy. One presented the results of analysis of vertices’ size in parallel plane to the film surface and towards perpendicular plane to it. Moreover, one performed an assessment of the distance between the grains using surface decomposition on Voronoi cell surface. In order to determine the film surface necessary to perform a particular microfinishing operation, one developed an index which is dependent on the overall profile of the film in the form of an envelope of the sum of vertices’ projections above a certain level. Studying the formation of diamond aggregates of abrasive grains and the spaces between them, one can conclude about the machining potential of microfinishing film and determine a recommended speed of the film displacement ensuring maximum utilization of this potential

A method and new parameters for assessing the active surface topography of diamond abrasive films

This paper describes the methodology and results of research on the tribological characteristics of the surfaces of diamond abrasive films using a stereometric analysis. Abrasive films are used in various finishing processes of surfaces with very high smoothness and accuracy. A morphological analysis of surface vertexes in the plane that is parallel to the film surface and the perpendicular direction allowed an assessment of the distances between particles by means of a decomposition of the surface into Voronoi cells. When studying the formation of the aggregates of diamond particles and the spaces between them, one may infer about the machining potential of the abrasive film and determine the recommended kinematic conditions of the film that ensures the maximum use of this potential. Owing to the investigations related to the morphology of diamond abrasive films, one can observe relevant characteristic abrasive aggregates that vary in term of size and shape depending on particle sizes. Units with elongated shapes have a superior machining ability in relation to spherical-shaped units. One of significant parameters proposed that describe the technological potential of abrasive films is the edge length to width ratio of diamond units. Different operating modes are discussed. A statistical analysis of the dynamics observed of abrasive interfaces allowed a pertinent description of the abrasive process taking into consideration nominal and apparent as well as abrasively efficient morphologies

Caractérisation fractale de la rugosité tridimensionnelle d'une surface

This paper reinvestigates some ideas concerning the fractal-based characterization of surface roughness. In a first stage we recall the relations between notions connected with the non differentiability of certain functions : Lipschitz-Hölder exponent, fractal dimension and spectral exponent. We show that the existence of a Lipschitz-Hölder exponent for each point of the surface is a sufficient condition to have a well-defined fractal dimension. This property does not imply that the underlying random function is non stationary, or some global self affinity property. However, around each point x, the existence of a Lipschitz-Hölder exponent $H$ implies that locally the function $z^*(\Delta) = z({\rm x} + \Delta) - z(\rm x)$ is a statistical self affine function, that is to say a function for which var $(z^*(\lambda\Delta)) = \lambda^{2 H}$ var $(z^*(\Delta))$ in a disk, the radius of which is characteristic of the surface. All these conclusions are supported by a computation based upon the use of the Weierstrass-Mandelbrot function and the Weierstrass one. Some 3D simulations of fractal surfaces are also presented on the basis of an original 2D extension of the Weierstrass function.Cet article fait le point sur un certain nombre d'idées concernant la caractérisation fractale de la rugosité des surfaces. On commence par rappeler les liens entre différentes notions liées au caractère non dérivable de certaines fonctions : exposant de Lipschitz-Hölder, dimension fractale et exposant spectral. On montre que l'existence d'un exposant de Lipschitz-Hölder en chaque point est une condition suffisante pour affirmer la nature fractale d'un objet. Cette propriéte n'implique ni la non-stationnarité du processus aléatoire sous-jacent, ni la propriété d'autoaffinité statistique. Cependant, à condition de ne pas sortir d'un disque dont le rayon est caractéristique de la surface considérée, l'existence d'un exposant de Lipschitz-Hölder implique que localement la fonction $z^*(\Delta) = z({\rm x} + \Delta) - z(\rm x)$ est une fonction statistiquement autoaffine, c'est-à-dire pour laquelle var $(z^*(\lambda\Delta)) = \lambda^{2 H}$ var $(z^*(\Delta))$. Les résultats théoriques sont illustrés à l'aide des fonctions de Weierstrass-Mandelbrot et de Weierstrass. On présente aussi une extension 2D de la fonction de Weierstrass permettant de générer des surfaces fractales. L'ensemble des résultats obtenus éclaire d'un jour nouveau la manière dont doit être abordée l'analyse fractale de la rugosité

Loss of the hematopoietic stem cell factor GATA2 in the osteogenic lineage impairs trabecularization and mechanical strength of bone

The transcription factor GATA2 is required for expansion and differentiation of hematopoietic stem cells (HSCs). In mesenchymal stem cells (MSCs), GATA2 blocks adipogenesis, but its biological relevance and underlying genomic events are unknown. We report a dual function of GATA2 in bone homeostasis. GATA2 in MSCs binds near genes involved in skeletal system development and colocalizes with motifs for FOX and HOX transcription factors, known regulators of skeletal development. Ectopic GATA2 blocks osteoblastogenesis by interfering with SMAD1/5/8 activation. MSC-specific deletion of GATA2 in mice increases the numbers and differentiation capacity of bone-derived precursors, resulting in elevated bone formation. Surprisingly, MSC-specific GATA2 deficiency impairs the trabecularization and mechanical strength of bone, involving reduced MSC expression of the osteoclast inhibitor osteoprotegerin and increased osteoclast numbers. Thus, GATA2 affects bone turnover via MSC-autonomous and indirect effects. By regulating bone trabecularization, GATA2 expression in the osteogenic lineage may contribute to the anatomical and cellular microenvironment of the HSC niche required for hematopoiesis