Otitis media microbes: culture, PCR, and confocal laser scanning microscopy

Otitis media microbes: culture, PCR, and confocal laser scanning microscopy Objectives: To assess the presence of middle ear pathogens in nasopharynx (NP), middle ear fluid (MEF), and middle ear mucosal swabs (MES) of 14 patients undergoing middle car sur cry. Methodology: Bacteria were assessed by culture and species specific PCR. Biofilm was investigated by confocal laser scanning microscopy (CLSM) of middle ear biopsies (MEBs). Results: Bacteria were absent in CLSM of MEBs in three of the four closed and healthy middle ears. Bacteria occurred in the ear with a foreign body (middle ear prosthesis), which showed localized living and dead bacteria, indicating biofilm. Bacterial growth was present in ten patient ears, but biofilm occurred in only one patient. CLSM indicated biofilm in the middle ear of two patients for whom PCR detected Haemophilus influenzae in the MEF. The three classical pathogens could frequently be found in the nasopharynx, by culture and PCR, but not from the middle ear. Alloiococcus otitidis was detected in the MEF of all five patients with open inflamed ears, though virtually absent from the nasopharynx. Pseudomonas aeruginosa was present in seven. It was the only pathogen found oil several occasions in all three locations in one patient. Conclusions: This study confirms the association of H. influenzae with middle ear biofilm, and indicates a potential role of P aeruginosa in middle ear inflammation and biofilm formation. Biofilm does not seem to cause inflammation. It is unclear whether the predominance of A. otitidis in chronically inflamed open middle ears indicates a pathogenic or contaminant role for this organism

Experimental damage identification in a post tensioned concrete beam

The paper deals with the results of an experimental campaign carried out on a post tensioned concrete beam with the aim of investigating the possibility to detect early warning signs of deterioration based on static and/or dynamic tests. The beam was tested in several configurations aimed to reproduce 5 different phases of the ‘life‘ of the beam: the original undamaged state, under increasing loss of tension in the post tensioning cables, during and after the formation of cracks at mid span, after a strengthening intervention carried out by means of a second tension cable, during and after the formation of further cracks on the strengthened beam. Responses of the beam were measured by an extensive set of instruments consisting of accelerometers, inclinometers, displacement transducers, strain gauges and optical fibers. The paper presents the test program and the dynamic characterization of the beam in the different damage scenarios in terms of the first modal frequency identified from dynamic tests. The evolution of the bending stiffness monitored during static tests is also reported and a simplified mechanical model of the cracked beam was proposed to interpret the correlation between the two parameters

Static and dynamic testing of a damaged post tensioned concrete beam

In this paper are reported the results of an experimental campaign carried out on a post tensioned concrete beam with the aim of investigating the possibility to detect early warning signs of deterioration basing on static and/or dynamic tests. The beam was tested in several configurations aimed to reproduce several different phases of the ‘life’ of the beam: the original undamaged state, increasing loss of tension in the post tensioning cables, a strengthening intervention carried out by means of a second tension cable, formation of further cracks on the strengthened beam. Responses of the beam were measured by an extensive set of instruments consisting of accelerometers, inclinometers, displacement transducers, strain gauges and optical fibres. The paper discusses the tests program and the dynamic characterization of the beam in the different damage scenarios. The modal properties of the beam in the different phases were recovered basing on the responses recorded on the beam during sine-sweep and impact hammer tests. The variation of the first modal frequency was studied to investigate the sensitivity of this parameter to both the cracking of the concrete section and the tension in the cables and also to compare results given by different types of experimental tests