Percorrer por autor "Santos, Carla"
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- Análise dinâmica do comportamento mecânico do ouvido médio com prótese totalPublication . Gentil, Fernanda; Marques, Marco; Garbe, Carolina; Santos, Carla; Parente, Marco; Martins, Pedro; Jorge, RenatoO presente trabalho tem como objetivo analisar e caracterizar o comportamento do ouvido médio quando uma prótese total substitui os elementos da cadeia ossicular de forma a solucionar problemas de surdez de transmissão. com base num modelo geométrico da cadeia ossicular saudável, a partir de imagens de TAC, foi criado um modelo onde uma prótese total foi incluída, assim como todos os objetos inerentes a esta adição. Foi assim efetuado o estudo dinâmico de vibrações forçadas para um modelo utilizando o método de elementos finitos. Foram obtidos os deslocamentos ao nível do umbo e da platina do estribo, para diferentes níveis de pressão sonora aplicada sobre a membrana timpânica, quando presente uma cartilagem na interface membrana-prótese de diferentes diâmetros e espessuras. Os resultados obtidos foram comparados com o modelo da cadeia tímpano-ossicular normal. A utilização deste modelo tem como objetivo conseguir definir a técnica que promove, da melhor maneira possível, a performance de uma prótese total no ouvido médio. Com este estudo pode-se afirmar que a reabilitação do ouvido médio com próstese do tipo TORP apresentará melhores resultados quando são utilizadas cartilagens de 4mm de diâmetro, com espessuras entre os 0.3mm e os 0.4mm.
- Analysis of eardrum pathologies using the finite element methodPublication . Gentil, Fernanda; Garbe, Carolina; Parente, Marco; Martins, Pedro; Ferreira, António; Jorge, Renato Natal; Santos, Carla; Paço, JoãoThis work investigates the effect of eardrum perforations and myringosclerosis in the mechanical behavior of the tympano-ossicular chain. A 3D model for the tympano-ossicular chain was created and different numerical simulations were made, using the finite element method. For the eardrum perforations, three different calibers of perforated eardrums were simulated. For the micro perforation (0.6 mm of diameter) no differences were observed between the perforated and normal eardrum. For the numerical simulation of the eardrum with the largest perforation caliber, small displacements were obtained in the stapes footplate, when compared with the model representative of normal ossicular-chain, at low frequencies, which is related with major hearing loss in this frequency range. For the numerical simulations of myringosclerosis, the larger differences in the displacement field between the normal and modified model were obtained in the umbo. When observing the results in the stapes footplate, there were no significant differences between the two models, which is in accordance to the clinical data. When simulating an eardrum perforation along with myringosclerosis, there is a decrease in the displacements, both from the umbo and the central part of the stapes footplate, often associated with a pronounced hearing loss. It could be concluded that the reduced displacement of the stapes footplate may be related to a greater hearing loss.
- Comparison of otoacoustic emissions in patients with tinnitus having normal hearing versus mild hearing lossPublication . Gentil, Fernanda; Meireles, Susana; Roza, Thuane; Santos, Carla; Parente, Marco; Almeida, Eurico; Natal, RenatoTinnitus is an auditory sensation whose source comes from external stimulus to the body. All studies that can help people with this disorder are very imperative. This study investigates the cochlear function in patients with tinnitus, using Distortion Products Otoacoustic Emissions (DPOAE). Ears where the subjects referred to feel the tinnitus were considered for the study group while other ears without this sensation of tinnitus acted as a control group. Fifty subjects suffering from unilateral or bilateral tinnitus with normal hearing sensitivity or mild hearing loss were recruited. Where comparing the control and study group, the highest percentage of cases of DPOAE detected was in the control group, although these differences were not statistically significant. When the analyzed frequency is the same as the tinnitus frequency, the prevalence of detected DPOAE is in tinnitus ears (50.0 %). In ears where tinnitus was not perceived (73.5 %) a p value of 0.024 (< 0.05) was found, which means that the undetected DPOAE could be influenced by tinnitus. Based on the results, tinnitus might not be caused by changes in the outer hair cells but seems to be affected by that.
- Computational simulation of the cupula behavior in vestibular pathologies of the inner earPublication . Santos, Carla; Gentil, Fernanda; Parente, Marco; Areias, Bruno; Belinha, Jorge; Natal Jorge, RenatoVertigo is reported as one of the most common symptoms in the world, commonly related with vestibular disorders. It is considered the third most frequent complaint in medicine, transmitting a sense of inadequacy and insecurity, mainly in elders. The aim of this work is to contribute to a better understanding on how the vestibular system works, mainly during vestibular rehabilitation process. This knowledge will help in the development of new techniques that will facilitate a more efficient rehabilitation. Vestibular rehabilitation consists in a set of exercises, known as maneuvers, that can reduce and even eliminate the symptoms of dizziness and imbalance associated with a vestibular disorder.
- Constructing and Using Multimodal Narratives to Research in Science Education: Contributions Based on Practical ClassroomPublication . Lopes, Joaquim; Silva, António; Cravino, José; Santos, Carla; Cunha, Ana; Pinto, José; Silva, Adília; Viegas, Clara; Saraiva, Maria; Branco, MariaThis study deals with the problem of how to collect genuine and useful data about science classroom practices, and preserving the complex and holistic nature of teaching and learning. Additionally, we were looking for an instrument that would allow comparability and verifiability for teaching and research purposes. Given the multimodality of teaching and learning processes, we developed the multimodal narrative (MN), which describes what happens during a task and incorporates data such as examples of students’ work.
- Efeito da Timpanosclerose na transmissão do som através do ouvido médioPublication . Gentil, Fernanda; Parente, Marco; Areias, Bruno; Santos, Carla; Natal, Renato; Gentil Costa, Maria FernandaA timpanosclerose é uma alteração do tecido conjuntivo subepitelial da membrana timpânica e dos ossículos do ouvido médio. Caracteriza-se pela deposição de placas com alta concentração de fosfato de cálcio. Isto leva a uma degradação das fibras de colagénio e origina uma calcificação distrófica Miringosclerose é o nome dado quando este processo se restringe apenas à membrana timpânica. quando invade também a cadeia ossicular denomina-se timpanosclerose. Há vários fatores que contribuem para esta formação de placas, como sejam, cicatrização da membrana timpânica, após a saída dos tubos de ventilação para drenagem de líquido do ouvido médio; otites; traumatismo da membrana timpânica ou, ainda, por causa autoimune, estes depósitos de cálcio formam-se como resposta a cicatrização do ouvido, produzindo células extra de cálcio. a miringosclerose, normalmente, é assintomática, sem causar perda auditiva. A timpanosclerose, pode originar surdez de transmissão. Esta depende da extensão das placas, da sua localização e grau de regidez na cadeia ossicular. Um estudo de K. Berdich mostra que a dimensão e a localização destas placas são mais relevantes para a surdez, do que o grau de calcificação. No presente estudo, o método dos elementos finitos é utilizado para comparar um modelo representativo do ouvido normal com 3 modelos diferentes (timpanosclerose apenas na membrana timpânica; afetando ainda o martelo; membrana timpânica e os três ossículos).
- Efeitos biomecânicos da evolução do colesteatoma sobre a corda do tímpanoPublication . Gentil, Fernanda; Mendonça, Leonor; Santos, Carla; Parente, Marco; Areias, Bruno; Natal, RenatoA otite média crónica pode levar ao aparecimento de um tumor benigno do ouvido, chamado colesteatoma. Esta patologia, se não for devidamente tratada, pode ter graves consequências. Uma delas pode resultar em paralisia facial se comprimir um ramo do nervo facial que atravessa o ouvido médio. Neste trabalho foram avaliadas as tensões exercidas do tumor contra o nervo. A maior tensão foi obtida na área de contacto entre o nervo e a bigorna.
- Effects of the fibers distribution in the human eardrum: A biomechanical studyPublication . Gentil, Fernanda; Parente, Marco; Martins, Pedro; Garbe, Carolina; Santos, Carla; Areias, Bruno; Branco, Carla; Paço, João; Jorge, Renato NatalThe eardrum separates the external ear from the middle ear and it is responsible to convert the acoustical energy into mechanical energy. It is divided by pars tensa and pars flaccida. The aim of this work is to analyze the susceptibility of the four quadrants of the pars tensa under negative pressure, to different lamina propria fibers distribution. The development of associated ear pathology, in particular the formation of retraction pockets, is also evaluated. To analyze these effects, a computational biomechanical model of the tympano-ossicular chain was constructed using computerized tomography images and based on the finite element method. Three fibers distributions in the eardrum middle layer were compared: case 1 (eardrum with a circular band of fibers surrounding all quadrants equally), case 2 (eardrum with a circular band of fibers that decreases in thickness in posterior quadrants), case 3 (eardrum without circular fibers in the posterior/superior quadrant). A static analysis was performed by applying approximately 3000Pa in the eardrum. The pars tensa of the eardrum was divided in four quadrants and the displacement of a central point of each quadrant analyzed. The largest displacements of the eardrum were obtained for the eardrum without circular fibers in the posterior/superior quadrant.
- Finite element modelling of sound transmission from outer to inner earPublication . Areias, Bruno; Santos, Carla; Natal Jorge, Renato M; Gentil, Fernanda; Parente, Marco P. L.The ear is one of the most complex organs in the human body. Sound is a sequence of pressure waves, which propagates through a compressible media such as air. The pinna concentrates the sound waves into the external auditory meatus. In this canal, the sound is conducted to the tympanic membrane. The tympanic membrane transforms the pressure variations into mechanical displacements, which are then transmitted to the ossicles. The vibration of the stapes footplate creates pressure waves in the fluid inside the cochlea; these pressure waves stimulate the hair cells, generating electrical signals which are sent to the brain through the cochlear nerve, where they are decoded. In this work, a three-dimensional finite element model of the human ear is developed. The model incorporates the tympanic membrane, ossicular bones, part of temporal bone (external auditory meatus and tympanic cavity), middle ear ligaments and tendons, cochlear fluid, skin, ear cartilage, jaw and the air in external auditory meatus and tympanic cavity. Using the finite element method, the magnitude and the phase angle of the umbo and stapes footplate displacement are calculated. Two slightly different models are used: one model takes into consideration the presence of air in the external auditory meatus while the other does not. The middle ear sound transfer function is determined for a stimulus of 60 dB SPL, applied to the outer surface of the air in the external auditory meatus. The obtained results are compared with previously published data in the literature. This study highlights the importance of external auditory meatus in the sound transmission. The pressure gain is calculated for the external auditory meatus.
- How the computational methods can contribute to better knowledge of the earPublication . Gentil, Fernanda; Parente, Marco; Santos, Carla; Areias, Bruno; Belinha, Jorge; Jorge, Renato NatalThe biomechanical behavior of the human ear can be studied using mathematical approaches, such as the finite element method. This methodology allows to perform simulations to evaluate the influence of sound transmission through all way of the ear, since the sound is selected by the outer ear to the inner ear. The finite element method is currently the preferred method for the numerical solution of partial differential equations, and it is used in several fields of the biological sciences. Due to its large applicability and efficiency, there are several works where this methodology is applied in different specialties, to analyze loads, strains or displacements, as in the case of the biomechanical study of the ear. From CT images, three-dimensional accurate computational models are created. The technique employs a set of calculations of numerical analysis for solutions of kinematic (displacements and rotations) and mechanical aspects (strength, stress, pressure, deformation). The use of these computer models enables the motion analysis of all ossicular chain points at any moment.