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Numerical study of Hough technique in surgery of otosclerosis, using the finite element method

Gentil F., Parente M., Martins P., Santos C., Almeida E., Ferreira A., Natali R.

Acta of Bioengineering and Biomechanics

2015

Vol. 17, no. 4

149--153

Purpose: Otosclerosis is a metabolic bone disease of the otic capsule that can cause the stapes fixation, resulting in conductive hearing loss or, in a profound sensorineural deafness threshold. Surgery is one of the possible treatments for the otosclerosis. To repair small focus of otosclerosis in the anterior crus of the stapes, in 1960, Hough suggested the implementation of a technique in which part of the anterior crus is fractured and the stapes turned. As a result, the posterior crus of the stapes is the only connection with the inner ear. In this work, the outcome of Hough’s surgical technique was simulated. Methods: Based on computerized images, a finite element model of middle ear ossicles and tympanic membrane was created, as well as a model where the stapes has changed. The discretization of the tridimensional solid model was made using the ABAQUS software. The mechanical properties used were taken from the literature and adequate boundary conditions were applied. Results: The results obtained with the Hough technique simulation were compared with a representative model of the normal ear, taking into account the displacements obtained on the central part of the stapes footplate and the maximum principal stress in the stapes crus. Conclusions: The results obtained are closer to the normal ear model, therefore Hough technique stands out as a good option to correct small focus of otosclerosis.

Optimization of a FBG-based filtering module for a 40 Gb/s OSSB transmission system

Drummond M. V., Silveira T., Silveira T., Ferreira A, Fonseca D., Nogueira R. N., Monteiro P.

Optica Applicata

2010

Vol. 40, nr 2

511--520

We present the optimization of an optical filtering module (OFM) of a single-channel 40 Gb/s transmission system with optical single-sideband modulation and alternate mark inversion signaling. Sideband suppression and dispersion compensation are simultaneously performed by the fiber Bragg grating (FBG) optical filtering through amplitude and phase response, respectively. Different amounts of accumulated dispersion are compensated using an OFM based on optical switches and chirped FBGs with different accumulated dispersion. Linear transmission simulations to assess the OFM effectiveness yield a Q-factor penalty variation lower than 1 dB relative to back-to-back considering a maximum accumulated dispersion of 20400 ps/nm. A transmission distance of 1040 km of nonlinear standard single mode fiber is achieved with a Q-factor higher than 7.

Evaluation of acoustical parameters of a Brazilian popular housing model

Ferreira A., Diniz F. B, Ferreira J.

Archives of Acoustics

2004

Vol. 29, no. 1

123-127

The present survey shows the results obtained from the evaluation of the acoustical parameters in situ, through standardized measurements, inside a popular residence designed to offer an option to combat the housing deficit of the low income Brazilian population.