157 research outputs found

    As cançÔes de Filipe de Sousa

    Get PDF
    Mestrado em MĂșsicaO presente estudo lança uma perspectiva abrangente sobre a obra para voz e piano de Filipe de Sousa (Maputo, 15/02/1927 — Lisboa, 22/11/2006). Apresenta um esboço biogrĂĄfico do compositor, apoiado na elaboração de um cronograma onde se reuniu uma sĂ©rie de dados referentes Ă  sua vida e obra, nas mĂșltiplas vertentes que assumiu como pianista, chefe de orquestra, professor , director do serviço de programas musicais da RTP, para alĂ©m da actividade de compositor. Integra ainda este trabalho, um catĂĄlogo exaustivo, ainda que nĂŁo definitivo, do seu espĂłlio artĂ­stico. A parte central da dissertação foi dedicada a um estudo individual de cada canção, focando aspectos da linguagem musical empregue, numa relação estreita com os respectivos textos poĂ©ticos, tendo sido alvo da nossa atenção a quase totalidade da sua actividade criativa nesta ĂĄrea. ABSTRACT: The present study intends to provide a comprehensive perspective on the works for voice and piano of Filipe de Sousa (Maputo, 15/02/1927 — Lisboa, 22/11/2006). It introduces a biographical sketch of the composer, supported by a chronogram where a diverse amount of information concerning his life and work is assembled, dealing with the multiple features that he assumed as a pianist, orchestra director, pedagogue, head of the music programs department of RTP, besides his composer activities. An exhaustive, even if not definitive, catalogue, of his artistic legacy, is also included. The main component of this dissertation is dedicated to a specific study of each song, focusing on its musical language aspects, and developing a relation with the respective poetical texts. The major part of the author’s creative activity in this domain is envisaged in our work

    Opto-mechanical eye models, a review on human vision applications and perspectives for use in industry

    Get PDF
    The purpose of this review is to aggregate technical information on existent optomechanical eye models (OME) described in the literature, for image quality assessment in different applications. Several physical eye models have been reviewed from peer-reviewed papers and patent applications. A typical eye model includes an artificial cornea, an intraocular lens or other lens to simulate the crystalline lens, an aperture as the pupil, and a posterior retinal surface, which may be connected to a light sensor. The interior of the eye model may be filled with a fluid to better emulate physiological conditions. The main focus of this review is the materials and physical characteristics used and the dimensional aspects of the main components including lenses, apertures, chambers, imaging sensors and filling medium. Various devices are described with their applications and technical details, which are systematically tabulated highlighting their main characteristics and applications. The models presented are detailed and discussed individually, and the features of different models are compared when applicable, highlighting strengths and limitations. In the end there is a brief discussion about the potential use of artificial eye models for industrial applications.This work is supported by European Structural and Investment Funds in the FEDER component, through the Operational Competitiveness and Internationalization Programme (COMPETE 2020) [Project nÂș 39479; Funding Reference: POCI-01-0247-FEDER-39479]

    Impact of contact lens materials on the mfERG response of the human retina

    Get PDF
    Purpose To investigate the effect of different hydrophilic and rigid gas-permeable contact lens (CL) materials on multifocal electroretinography (mfERG). Methods The mfERG was recorded in 18 healthy subjects with RETI-port/scan21 (TM): 11 subjects underwent mfERG recording wearing two different hydrophilic CLs with different water contents in a randomized order (1 silicone hydrogel-Comfilcon A, 48%EWC, and 1 hydrogel-Omafilcon A, 62% EWC) and 7 other subjects wore a hydrophobic rigid gas-permeable scleral lens (SL)-Hexafocon A. Control measures were recorded without CL in both groups. mfERG recordings were performed with a stimulus array pattern of 103-scaled hexagons displayed on a 19-inch RGB monitor at 28 cm distance at a frame rate of 60 Hz. The amplitude (nV), implicit time and response density (nV/deg(2)) of the first-order kernel components N1, P1 and N2 were evaluated for the total mfERG response and for the response averages of 4 quadrants and of 6 successive concentric rings. Subjects were optically corrected for the working distance of ERG display. Results Hydrophobic material significantly decreased the P1 amplitude of the total mfERG response, at Rings 3, 4 and 6 and Quadrant 4 (> 53.77 +/- 43.2 nV; P <= 0.050), as well as the total (- 71.59 +/- 50.68 nV) and Ring 6 (- 104.76 +/- 79.88 nV) N2 amplitude (P <= 0.043). N1, P1 and N2 peak times suffered significant changes with both hydrophilic CL (P <= 0.050). Omafilcon A significantly increased P1 amplitude of Ring 5 and N2 amplitude of Ring 4, when compared to baseline (52.40 +/- 71.87 nV; P = 0.036) and to Comfilcon A (39.51 +/- 48.63 nV; P = 0.023), respectively. Conclusions Hydrophobic CL slightly attenuated the strength of the mfERG signal, especially at the middle to peripheral retinal areas, while hydrophilic CL slightly changed the implicit time of the response. Different hydrophilic CL materials might affect the mfERG response differently. When considering the measurement of mfERG obtained with a CL in place, researchers should bear in mind thThis project was supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of projects PTDC/FIS-OPT/0677/2014 and the FCT Strategic Funding UID/FIS/04650/2013, FCT- SFRH/BPD/92365/2013 and SFRH/BD/136684/2018

    Assessment of the human retinal neural selectivity to square gratings’ orientation with the multifocal and pattern electroretinograms

    Get PDF
    The retinal response to particular orientations might start a signaling cascade of events that help to modulate eye growth and respond to myopia control treatments. The purpose of this study was to investigate the retinal electrical activity in response to grids of different spatial orientations. The multifocal (mfERG) and pattern (PERG) ERG responses of nine eyes (spherical equivalent of −0.45 ± 1.15 D; mean age of 32.9 ± 7.7 years) were recorded with four grids (1.2 cpd) oriented at 60◩, 90◩ , 120◩ and 180◩ under pupils’ dilation. The mfERG was analyzed by retinal eccentricity, quadrants and meridians with the same orientation of the grids. The response density of mfERG, the amplitudes of PERG and the implicit times of each peak from both tests were analyzed. The grid’s orientation did not evoke different implicit times in both tests. All retinal meridians showed higher response density with grids of parallel orientation to the meridian and lower response density with perpendicularly oriented grids. These differences were statistically significant in the horizontal and 60◩ meridians (p < 0.050). PERG response did not change with the grids’ orientations. The mfERG was sensitive to detect changes in the outer retinal activity with variations in stimulus orientation. The paradigm of meridional analysis of mfERG results might be more sensitive to orientation changes than the traditional analysis by rings, quadrants or hemifields.This research was funded by the Portuguese Foundation for Science and Technology (FCT) in the framework of projects PTDC/FIS-OPT/0677/2014, the FCT Strategic Funding UID/FIS/04650/2013, FCT-SFRH/BPD/92365/2013 and SFRH/BD/136684/2018

    Blue light blind-spot stimulation upregulates b-wave and pattern ERG activity in myopes

    Get PDF
    Upregulation of retinal dopaminergic activity may be a target treatment for myopia progression. This study aimed to explore the viability of inducing changes in retinal electrical activity with short-wavelength light targeting melanopsin-expressing retinal ganglion cells (ipRGCs) passing through the optic nerve head. Fifteen healthy non-myopic or myopic young adults were recruited and underwent stimulation with blue light using a virtual reality headset device. Amplitudes and implicit times from photopic 3.0 b-wave and pattern electroretinogram (PERG) were measured at baseline and 10 and 20 min after stimulation. Relative changes were compared between non-myopes and myopes. The ERG b-wave amplitude was significantly larger 20 min after blind-spot stimulation compared to baseline (p<0.001) and 10 min (p<0.001) post-stimulation. PERG amplitude P50-N95 also showed a significant main effect for 'Time after stimulation' (p<0.050). Implicit times showed no differences following blind-spot stimulation. PERG and b-wave changes after blind-spot stimulation were stronger in myopes than non-myopes. It is possible to induce significant changes in retinal electrical activity by stimulating ipRGCs axons at the optic nerve head with blue light. The results suggest that the changes in retinal electrical activity are located at the inner plexiform layer and are likely to involve the dopaminergic system.This work was supported by the Federal Ministry of Education and Research, Industrie-in-Klinik-Plattform Program BMBF, Germany (FKZ: 13GW0256). This project was also supported by the Portuguese Foundation for Science and Technology (FCT) PTDC/FIS-OPT/0677/2014, the Strategic Funding UID/FIS/04650/2013 at Center of Physics, UMinho, and predoctoral grant SFRH/BD/136684/2018 to AAS. In addition, we would like to thank Nikita Wong for some literature search and language proofreading

    Changes in choroidal thickness and retinal activity with a myopia control contact lens

    Get PDF
    Purpose: The axial elongation in myopia is associated with some structural and functional retinal changes. The purpose of this study was to investigate the effect of a contact lens (CL) intended for myopia control on the choroidal thickness (ChT) and the retinal electrical response. Methods: Ten myopic eyes (10 subjects, 18–35 years of age) with spherical equivalents from −0.75 to −6.00 diopters (D) were enrolled. The ChT at different eccentricities (3 mm temporal, 1.5 mm temporal, sub-foveal ChT, 1.5 mm nasal, and 3 mm nasal), the photopic 3.0 b-wave of ffERG and the PERG were recorded and compared with two material-matched contact lenses following 30 min of wear: a single-vision CL (SV) and a radial power gradient CL with +1.50 D addition (PG). Results: Compared with the SV, the PG increased the ChT at all eccentricities, with statistically significant differences at 3.0 mm temporal (10.30 ± 11.51 ”m, p = 0.020), in sub-foveal ChT (17.00 ± 20.01 ”m, p = 0.025), and at 1.5 mm nasal (10.70 ± 14.50 ”m, p = 0.044). The PG decreased significantly the SV amplitude of the ffERG photopic b-wave (11.80 (30.55) ”V, p = 0.047), N35-P50 (0.90 (0.96) ”V, p = 0.017), and P50-N95 (0.46 (2.50) ”V, p = 0.047). The amplitude of the a-wave was negatively correlated with the ChT at 3.0T (r = −0.606, p = 0.038) and 1.5T (r = −0.748, p = 0.013), and the amplitude of the b-wave showed a negative correlation with the ChT at 1.5T (r = −0.693, p = 0.026). Conclusions: The PG increased the ChT in a similar magnitude observed in previous studies. These CLs attenuated the amplitude of the retinal response, possibly due to the combined effect of the induced peripheral defocus high-order aberrations impacting the central retinal image. The decrease in the response of bipolar and ganglion cells suggests a potential retrograde feedback signaling effect from the inner to outer retinal layers observed in previous studies.This work was funded by the Portuguese Foundation for Science and Technology (FCT) in the framework of projects PTDC/FIS-OPT/0677/2014, the FCT Strategic Funding UID/FIS/04650/2013, FCT-SFRH/BPD/92365/2013 and SFRH/BD/136684/2018

    Morfología corneal y resultados visuales en pacientes con LASIK después de ortoqueratología

    Get PDF
    [Extracto] JustificaciĂłn y objetivos - Comparar la morfologĂ­a corneal y los resultados visuales de los usuarios de lentes contacto blandas (controle) y ortoqueratologĂ­a (OK) a largo plazo sometidos a cirugĂ­a refractiva corneal (LASIK) para la correcciĂłn de la miopĂ­a. [...]info:eu-repo/semantics/publishedVersio

    The impact of overnight orthokeratology on accommodative response in myopic subjects

    Get PDF
    This study aimed to evaluate the effects of two months of orthokeratology (OK) treatment in the accommodative response of young adult myopes. Twenty eyes (21.8 ± 1.8 years) were fitted with the Paragon CRTÂź 100 LENS to treat myopia between −1.00 and −2.00 D. Low- and high-contrast visual acuity (LCDVA and HCDVA), central objective refraction, light disturbance (LD), and objective accommodative response (using the Grand Seiko WAM-5500 open-field autorefractometer coupled with a Badal system) were measured at baseline (BL) before lens wear and after 1, 15, 30, and 60 nights of OK. Refractive error correction was achieved during the first fifty days of OK lens wear, with minimal changes afterwards. LD analysis showed a transient increase followed by a reduction to baseline levels over the first 30 nights of treatment. The accommodative response was lower than expected for all target vergences in all visits (BL: 0.61 D at 1.00 D to 0.96 D at 5.00 D; 60 N: 0.36 D at 1.00 D to 0.79 D at 5.00 D). On average, the accommodative lag decreases over time with OK lens wear. However, these differences were not statistically significant (p > 0.050, repeated-measures ANOVA and Friedman test). This shows that overnight OK treatment does not affect objectively measured the accommodative response of young, low myopic eyes after two months of treatment stabilization.This research was supported by the Portuguese Foundation for Science and Technology (FCT) PTDC/FIS-OPT/0677/2014, the Strategic Funding UID/FIS/04650/2013 at Center of Physics, UMinho, and predoctoral grant SFRH/BD/136684/2018 to A.A.S

    Increase in b-wave amplitude after light stimulation of the blind spot is positively correlated with the axial length of myopic individuals

    Get PDF
    Altered retinal dopamine and ON-pathway activity may underlie myopia development. It has been shown that the stimulation of the blind spot with short-wavelength light increases the electroretinogram (ERG) b-wave amplitude of myopic eyes and may engage the retinal dopaminergic system. This study evaluated the impact of various durations of blind spot stimulation on the electrophysiological response of the myopic retina and their relationship to axial length. Six myopic individuals underwent three short-wavelength blue light blind spot stimulation protocols (10 s, 1 min, 10 min) using a virtual reality headset. As a control condition, no stimulation was shown for 1 min. The b-wave amplitude of the photopic full-field ERG was measured at baseline and 10, 20, 30, 40, 50, and 60 min after each condition. A significant increase in b-wave amplitude was observed for all stimulation protocols compared to the control. The peak b-wave amplitude was observed 20 min after the 1-min stimulation protocol and 60 min after the 10-min stimulation protocol. A significant positive correlation was found between axial length of the eye and percent change in b-wave amplitude for the 10-min stimulation protocol. A rapid and a delayed b-wave time course responses were observed following 1 min and 10 min of blind spot stimulation, respectively. Overall, these results indicate that light stimulation of the blind spot for various durations elevates ON-bipolar cell activity in the retina and as such is assumed to reduce the myopic response. These findings could have implications for future myopia treatment.This work was supported by the Federal Ministry of Education and Research, Industrie-in-Klinik-Plattform Program BMBF, Germany (FKZ: 13GW0256). This project was also supported by the Portuguese Foundation for Science and Technology (FCT) PTDC/FIS-OPT/0677/2014, the Strategic Funding UID/FIS/04650/2013 at Center of Physics, UMinho, and predoctoral grant SFRH/BD/136684/2018 to AAS

    Relative peripheral refraction across 4 meridians after orthokeratology and LASIK surgery

    Get PDF
    Background: To characterize the axial and off-axis refraction across four meridians of the retina in myopic eyes before and after Orthokeratology (OK) and LASIK surgery. Methods: Sixty right eyes with a spherical equivalent (M) between − 0.75 to − 5.25 D (cylinder <− 1.00 D) underwent LASIK (n = 26) or OK (n = 34) to treat myopia. Axial and off-axis refraction were measured with an open-field autorefractometer before and after stabilized treatments. Off-axis measurements were obtained for the horizontal (35° nasal and temporal retina) and vertical (15° superior and inferior retina) meridians, and for two oblique directions (45–225° and 135–315°) up to 20° of eccentricity. The refractive profile was addressed as relative peripheral refractive error (RPRE). Results: OK and LASIK post-treatment results showed an increase of myopic relative refraction at several eccentric locations. At the four meridians evaluated, the M component of the pre-treatment RPRE values was not statistically different (p > 0.05) from the post-treatment RPRE within 30° and 20° of the central visual field after LASIK and OK, respectively. These results demonstrated that the treatment zone warrants an optimal central field of vision. Conclusions: The present study gives an overview of RPRE after refractive corneal reshaping treatments (OK and LASIK) across vertical, horizontal and two oblique meridians together. This allows a 3D representation of RPRE at the retina and shows that the myopic shift induced by both treatments is more relevant in horizontal directions.Supported in part by a grant to AQ (SFRH/BD/61768/2009), projects PTDC/ SAU-BEB/098391/2008, PTDC/SAU-BEB/098392/2008 and the Strategic Project PEST-C/FIS/UI607/2011 from the Science and Technology Foundation of Portuguese Ministry of Science and Higher Education.info:eu-repo/semantics/publishedVersio
    • 

    corecore