Analysis of retinal fundus images have been proven to provide relevant information about the diagnoses of several pathologies. Among them, glaucoma stands out as an important pathology due to the need for early treatment. Moreover, the relationship between optic disc and optic cup regions provided by retinal fundus image analysis can aid in diagnosis. Automatically generating such a relation is, therefore, an important feature for ensuring quicker and more precise conclusions. This paper evaluates the use of Conditional GAN (Generative Adversarial Networks) for an optic disc and optic cup segmentation task. Conditional GANs are hybrid machine learning models that are able to generate data based on conditioned training. The results demonstrate that the addressed method generates valid segmentation images for optic disc and optic cup location, with approximately 95% and 85% accuracy, respectively
KEYWORDS: Signal to noise ratio, Charge-coupled devices, Autoregressive models, Stars, Electron multiplying charge coupled devices, Cameras, Radon, Optimization (mathematics), Telescopes, Control systems
We present the optimization method for the electron multiplying charge coupled devices of the acquisition system of the SPARC4 (OMASS4). The OMASS4 uses as figures of merit the signal-to-noise ratio (SNR) and the acquisition rate (AR) as a function of the operation mode of the CCDs. Three different modes of optimization are included in the OMASS4: (1) optimization of SNR only; (2) optimization of AR only; and (3) optimization of both SNR and AR simultaneously. The first two modes calculate an analytical maximization of the cost function, whereas the third mode uses the Bayesian optimization method to determine the optimum mode of operation. We apply the OMASS4 to find the optimum mode for observations obtained at the Pico dos Dias Observatory, Brazil and compare the delivered modes of operation and its performance with the ones adopted by the observer. If the OMASS4 had been used as a tool to optimize the CCDs in all of these nights, it would be possible to improve their efficiency in 97.17%, 65.08%, and 77.66% for the optimization modes 1, 2, and 3, respectively.
We demonstrate the potential of applying hollow core and negative curvature optical fibers (HC-NCF) as efficient sensors to monitor the concentration of three high-toxicity gases: methane (CH4), carbon monoxide (CO), and nitrogen monoxide (NO). Numerical simulations demonstrate that the insertion of holes in such fibers guarantees the entry of these gases into their hollow core and allows strong interaction of these gases with the low-loss mode propagating in the HC-NCF. This interaction between light and gas in spectral regions with high gas absorption allows one to monitor reduced concentrations of these gases present in the environment simply by monitoring the optical power at the fiber output. The results show a linear behavior of propagation losses as a function of concentrations of 0% to 100% of CO and NO gas, and for concentrations of 0% to 5% of CH4 gas. This linearity between the propagation losses and the variation of the concentrations of gases in the environment can promote its application in healthcare and environment, to monitor low concentrations of gases ensuring high speed and accuracy.
Quasiconformal transformation optics is used to design two-dimensional polarization beam splitters. The resulting media present inhomogeneous uniaxial permittivity and nonmagnetic response. The compact devices are theoretically designed and investigated for symmetrical and asymmetrical geometries, with footprint of 64 and 110 μm2, respectively. The polarization splitter performance is evaluated for the fundamental mode and third mode, exhibiting an insertion loss closer to 0 dB and extinction ratio above 40 dB over a broad wavelength range.
A silicon nitride directional coupler filled with toluene is proposed as temperature sensor. This liquid material has a high thermo-optic coefficient, which allows large variations on its refractive index in function of temperature variations. Simulations were performed to obtain the sensor's sensitivities, which measured on the output ports (P2, P3) of the structure are 0:11392= °C and 0:11499= °C, respectively.
An index-guiding photonic crystal fiber with one hole adjacent to the solid core filled with liquid is theoretically and
experimentally investigated. The use of an index-matched liquid induces efficient and short-range coupling from the
solid core to the fluidic channel and back, which can be used to optically probe and/or pump the inserted liquid.
Experimentally, the use of a micropipette allowed for selective filling the desired air hole. By varying the filled fiber
length, the periodicity of the observed spectral modulation could be tuned. One fiber sample was then filled with a CdSe
quantum dot colloid; pumping via the solid core resulted in photoluminescence that partially exited the fiber via the solid
core, showing the filled waveguide's potential to offer distributed quantum dot pumping and an efficient collection
method for the generated spontaneous emission.
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