CLASSIFICATION OF IMAGES BASED ON PIXELS THAT REPRESENT A SMALL PART OF THE SCENE. A CASE APPLIED TO MICROANEURYSMS IN FUNDUS RETINA IMAGES

Convolutional Neural Networks (CNNs), the state of the art in image classification, have proven to be as effective as an ophthalmologist, when detecting Referable Diabetic Retinopathy (RDR). Having a size of less than 1\% of the total image, microaneurysms are early lesions in DR that are difficult to classify. The purpose of this thesis is to improve the accuracy of detection of microaneurysms using a model that includes two CNNs with different input image sizes, 60x60 and 420x420 pixels. These models were trained using the Kaggle and Messidor datasets and tested independently against the Kaggle dataset, showing a sensitivity of 95\% and 91\%, a specificity of 98\% and 93\%, and an area under the Receiver Operating Characteristics curve of 0.98 and 0.96, respectively, in the sliced images. Furthermore, by combining these trained models, there was a reduction of false positives for complete images by about 50\% and a sensitivity of 96\% when tested against the DIARETDB1 dataset . In addition, a powerful image pre-processing procedure was implemented, which included adjusting luminescence and color reduction, improving not only images for annotations, but also decreasing the number of epochs during training. Finally, a novel feedback operation that re-sent batches not classified as well as expected, increased the accuracy of the CNN 420 x 420 pixel input model

Disentangling enantiosensitivity from dichroism using bichromatic fields

We discuss how tensorial observables, available in photoelectron angular distributions resulting from interaction between isotropic chiral samples and cross polarized $\omega$-$2\omega$ bichromatic fields, allow for chiral discrimination without chiral light and within the electric-dipole approximation. We extend the concept of chiral setup [Phys. Rev. A 98, 063428 (2018)], which explains how chiral discrimination can be achieved in the absence of chiral light, to the case of tensorial observables. We derive selection rules for the enantiosensitivity and dichroism of the $b_{l,m}$ coefficients describing the photoelectron angular distribution valid for both weak and strong fields and for arbitrary $\omega$-$2\omega$ relative phase. Explicit expressions for simple perturbative cases are given. We find that, besides the dichroic non-enantiosensitive [J. Chem. Phys. 151 074106 (2019)], and dichroic-and-enantiosensitive $b_{l,m}$ coefficients found recently [Phys. Rev. A 99, 063406 (2019)], there are also enantiosensitive non-dichroic $b_{l,m}$ coefficients. These reveal the molecular enantiomer independently of the relative phase between the two colors and are therefore observable even in the absence of stabilization of the $\omega$-$2\omega$ relative phase.Comment: 18 pages, 3 figure

On the molecular information revealed by photoelectron angular distributions of isotropic samples

We propose an alternative approach to the description and analysis of photoelectron angular distributions (PADs) resulting from isotropic samples in the case of few-photon absorption via electric fields of arbitrary polarization. As we demonstrate for the one- and two-photon cases, this approach reveals the molecular frame information encoded in the $b_{l,m}$ expansion coefficients of the PAD in a particularly clear way. Our approach does not rely on explicit partial wave expansions of the scattering wave function and the expressions we obtain are therefore interpreted in terms of the vector field structure of the photoionization dipole $\vec{D}(\vec{k})$ as a function of the photoelectron momentum $\vec{k}$. This provides very compact expressions that reveal how molecular rotational invariants couple to the setup (electric field polarization and detectors) rotational invariants. We rely heavily on this approach in a companion paper on tensorial chiral setups. Here we apply this approach to one-photon ionization and find that while $b_{0,0}$ depends only on the magnitude of $\vec{D}(\vec{k})$, $b_{1,0}$ (non-zero for chiral molecules) is sensitive only to the components of $\vec{D}(\vec{k})$ perpendicular to $\vec{k}$ encoded in the propensity field $\vec{B}(\vec{k})\equiv i\vec{D}^{*}(\vec{k})\times\vec{D}(\vec{k})$, and $b_{2,0}$ is sensitive only to the the component of $\vec{D}(\vec{k})$ along $\vec{k}$. We also analyze the resonantly enhanced two-photon case where we show that $b_{0,0}$ and $b_{1,0}$ can be written in terms of an effectively stretched $\vec{D}(\vec{k})$, and that $b_{1,0}$ and $b_{3,0}$ reveal structural information of the field $\vec{B}(\vec{k})$ encoded in three of its vector spherical harmonic expansion coefficients.Comment: 26 pages, 5 figure

A previous note regarding the influence of a 6-weeks mixed protocol on plasmatic carbonyl groups in high-performance athletes with mental retardation

It is widely accepted that high physical performance may be associated to oxidative damage. The present study was undertaken to ascertain the influence of a mixed protocol based on regular exercise and antioxidant supplementation in plasmatic carbonyl group content in athletes with mental retardation. Mainly if we take into account individuals with mental retardation generally present high levels of oxidative damage. Fifty-five high-performance athletes with mental retardation from Special Olympics volunteered for this study (21.6±1.8 years-old). Fourty were randomly included in experimental group to perform a 6-weeks protocol including exercise (low-moderate intensity aerobic exercise before breakfast 3 times per week) and supplementation (1g ascorbic acid + 400 UI α-tocopherol 6 times per week). Control group included 15 age, sex, trained and BMI-matched athletes with mental retardation who did not perform the mixed protocol. Written informed consent was obtained. Further the protocol was approved by an institutional ethic committee. Protein oxidation expressed in terms of plasmatic carbonyl group levels were determined by high performance liquid chromatography (HPLC) with fluorimetric detection as described elsewhere, 72-hours before starting the protocol (pre-test) and after its ending (post-test). When compared to baseline carbonyl group levels were decreased significantly after the 6-weeks protocol (1.98±0.2 vs 1.16 ±0.1; p\u3c0.001). No changes were reported in controls. It was concluded that a 6-weeks mixed protocol reduced carbonyl group levels in athletes with mental retardation. Further studies on this topic are highly required