Biomedical subjects

C Caroni

Publications and source records attributed to C Caroni.

5 recordsLinked to original sources

PubMed2005

Graphical tests for the assumption of gamma and inverse Gaussian frailty distributions.

The common choices of frailty distribution in lifetime data models include the Gamma and Inverse Gaussian distributions. We present diagnostic plots for these distributions when frailty operates in a proportional hazards framework. Firstly, we present plots based on the form of the unconditional survival function when the baseline hazard is assumed to be Weibull. Secondly, we base a plot on a closure property that applies for any baseline hazard, namely, that the frailty distribution among survivors at time t has the same form as the original distribution, with the same shape parameter but different scale parameter. We estimate the shape parameter at different values of t and examine whether it is constant, that is, whether plotted values form a straight line parallel to the time axis. We provide simulation results assuming Weibull baseline hazard and an example to illustrate the methods.

Greece↗

PubMed2002

The correct "ball bearings" data.

The famous data on fatigue failure times of ball bearings have been quoted incorrectly from Lieblein and Zelen's original paper. The correct data include censored values, as well as non-fatigue failures that must be handled appropriately. They could be described by a mixture of Weibull distributions, corresponding to different modes of failure.

Equipment Failure Analysis↗

PubMed1998

Color stability of provisional resin restorative materials.

STATEMENT OF PROBLEM: Use of temporary crowns and fixed partial dentures is especially relevant when the treatment plan requires restorations for long interim periods, and the in-service discoloration of provisional restorative materials is a major drawback. PURPOSE: This study evaluated the discoloration effect of coffee and tea on some materials that are commonly used in the fabrication of provisional restorations. MATERIAL AND METHODS: Six commercially available provisional resins (Jet, Caulk TBR, Protemp Garant, Luxatemp Solar, Provipont DC and SR-Ivocron-PE) were evaluated after 1 day, 7 days, and 30 days of immersion in various staining solutions. Color measurements were obtained by using a Dr Lange Micro Color tristimulus colorimeter and color differences (delta E*) were estimated. RESULTS: The 2 chemically activated resins (Jet and Caulk TBR) and the heat-cured resin (SR-Ivocron PE) exhibited the least color changes, whereas the Provipont-DC resin was the least color stable. After immersion for 30 days, the combination with the coffee solution resulted in unacceptable discoloration for all the tested materials. CONCLUSIONS: Provisional restorative materials, staining solutions, and immersion time were significant factors that affected color stability. After immersion for 7 days, all materials showed observable color changes. The composite-based materials, especially light-curing composites, were the least color stable. The coffee solution exhibited more staining capacity than the tea solution.

Analysis of Variance↗

PubMed1987

Inhibition of BK virus haemagglutination by gangliosides.

The effect of gangliosides extracted from human group O Rh+ erythrocytes on haemagglutination by BK virus was investigated. Experiments were performed on both ganglioside mixtures and isolated fractions separated by column chromatography and characterized by thin-layer chromatography. These results were compared with those obtained with standard preparations of gangliosides, and the inhibiting activity was shown to be confined mainly to gangliosides with a RF lower than GM1. It was also observed that the insertion of gangliosides in liposomes increased the haemagglutination-inhibiting activity and that ganglioside coating restored the ability of glycosidase-treated human red blood cells to agglutinate.

BK Virus↗

PubMedDate not supplied

Prevalence of sexually transmitted infections in female sex workers in Athens, Greece - 2005.

There is little data on the prevalence of STIs in female sex workers, Greek and immigrants, working in Athens, Greece, since most of them work without any form of official license. Our aim was to establish the prevalence of STIs in asymptomatic legal Greek and immigrant female sex workers in Athens, Greece. The study involved an evaluation of gonococcal and chlamydial infection, early infectious syphilis, HIV infection, HSV-2 infection, Hepatitis B and C in 299 female sex workers who applied for an official work permit between May 2005 and October 2005. HSV-2 infection was more common in the Greek sex workers. No difference was found for the other STIs. Prevalence was related to age. A significant association was found between HSV-2 and syphilis. No HIV infection was detected. We concluded that asymptomatic sex workers can be a source of STIs which points out the need for a better health system control in Greece.

Adult↗