Deep Semi-Supervised and Self-Supervised Learning for Diabetic Retinopathy Detection

Diabetic retinopathy (DR) is one of the leading causes of blindness in the working-age population of developed countries, caused by a side effect of diabetes that reduces the blood supply to the retina. Deep neural networks have been widely used in automated systems for DR classification on eye fundus images. However, these models need a large number of annotated images. In the medical domain, annotations from experts are costly, tedious, and time-consuming; as a result, a limited number of annotated images are available. This paper presents a semi-supervised method that leverages unlabeled images and labeled ones to train a model that detects diabetic retinopathy. The proposed method uses unsupervised pretraining via self-supervised learning followed by supervised fine-tuning with a small set of labeled images and knowledge distillation to increase the performance in classification task. This method was evaluated on the EyePACS test and Messidor-2 dataset achieving 0.94 and 0.89 AUC respectively using only 2% of EyePACS train labeled images

Diseño microelectrónico de un convertidor analógico digital en tecnología CMOS.

Proyecto de Graduación (Licenciatura en Ingeniería Electrónica) Instituto Tecnológico de Costa Rica, Escuela de Ingeniería en Electrónica, 2012.The advance of technology has increasingly influenced many different fields, in which food industry was no exception. That is the reason everyday people look for more efficient processes to get benefits during the production process. DEMASA Company has seen this technological raise as a chance to get first class products to be marketed in national and international marketplaces. What DEMASA expects by developing this project is to improve the production process of the lines that complement TOSTY Brand, especially potato chips such as: “PAPITOSTY” and “PAPIOLAS.” This because currently there are not controls over the variables that influence products fabrication regarding the potato hopper, quantity of raw material in the process, water, air, fryer temperature, conveyor belt speed, and engine control. If these variables are not rightly manipulated, there can appear several problems which can be: stop on the production waste of air and water, turn engines on unnecessarily, inappropriate fry temperature, or something even more serious such as the drop down of the products final quality or problems with product’s quantity which may produces economical loss to the company. By analyzing the situation, it can be concluded that those problems can be avoided and they are a consequence of the lack of control variables during the process. The solution to the problems is to perform a centralized system where people can have control and monitor the production process variables.Instituto Tecnológico de Costa Rica. Escuela de Ingeniería Electrónica

“La Gestión Comercial y su relación con el desarrollo de un Plan Estratégico en la empresa Comsatel Perú 2016”

La tesis de investigación tuvo como objetivo general determinar el nivel de relación entre la Gestión Comercial y el desarrollo del plan estratégico en la empresa Comsatel Perú 2016, el que se cumplió. Es un estudio descriptivo en el que se evaluaron cuatro aspectos en la variable gestión comercial: comercialización, servicio al cliente, marketing mix e investigación comercial; y otros cuatro en la variable plan estratégico: análisis de la situación, establecimiento de objetivos y estrategias, implementación de la estrategia y control de la estrategia comercial. El diseño de la investigación es no experimental de tipo transversal. Para la medición de la variable se utilizó la encuesta, usando como instrumento. El procesamiento estadístico de los datos se realizó por medio de la aplicación del programa estadístico SPSS versión 22, se trabajó con una población de 33 colaboradores, así mismo se demostró la hipótesis plantada como cierta

Dendritic cells and glioblastoma

Los gliomas son las neoplasias malignas intracraneales primarias más diagnosticadas en adultos. Los tratamientos disponibles en la actualidad sólo han proporcionado mejoras modestas en la supervivencia global y siguen estando limitados por la inevitable recurrencia local, lo que hace necesaria la exploración de terapias novedosas. Entre los enfoques que se están investigando, uno de los principales contendientes es la inmunoterapia, cuyo objetivo es modular las vías inmunitarias para estimular la destrucción selectiva de las células malignas. Las células dendríticas (CD) son potentes iniciadores de respuestas inmunitarias adaptativas y, por tanto, actores cruciales en el desarrollo y el éxito de la inmunoterapia. Los ensayos clínicos de diversas vacunas basadas en DC han demostrado la inducción de respuestas inmunitarias antitumorales y la prolongación de la supervivencia en el contexto de muchos tipos de cáncer. En este capítulo se revisa la bibliografía actual sobre las CD y su papel en el microambiente tumoral, su aplicación y uso clínico actual en la inmunoterapia del glioma maligno y las vías futuras para desarrollar vacunas antitumorales exitosas basadas en CD. 2023 Elsevier Inc. Todos los derechos reservados.Gliomas are the most diagnosed primary intracranial malignancies in adults. Currently available treatments have provided only modest improvements in overall survival and remain limited by inevitable local recurrence, necessitating the exploration of novel therapies. Among approaches being investigated, one of the leading contenders is immunotherapy, which aims to modulate immune pathways to stimulate the selective destruction of malignant cells. Dendritic cells (DCs) are potent initiators of adaptive immune responses and, therefore, crucial players in the development and success of immunotherapy. Clinical trials of various DC-based vaccinations have demonstrated the induction of antitumor immune responses and prolonged survival in the setting of many cancers. This chapter reviews the current literature regarding DCs and their role in the tumor microenvironment, their application and current clinical use in malignant glioma immunotherapy, and future avenues for developing successful antitumor DC-based vaccines. © 2023 Elsevier Inc. All rights reserved

Estudio de la hidrodinámica de la ciénaga La Villa (Machado) y sus interconexiones en la ecorregión de La Mojana a través de la mecánica de fluidos computacional

Las condiciones atípicas que se presentaron con el fenómeno de la niña durante los años 2010-2011 pusieron en evidencia nacional las falencias en la ecorregión de La Mojana en cuanto a planificación y control de inundaciones. Por tanto, identificar el comportamiento hidrodinámico de los cuerpos cenagosos ayudará a establecer soluciones respecto a la sostenibilidad del recurso hídrico y a sistemas de alertas tempranas a la población en condición de riesgo. El objetivo principal de la presente investigación, es evaluar el comportamiento hidrodinámico del hidrosistema cenagoso La Villa (Machado) que hace parte de la región de La Mojana, mediante un modelo numérico bidimensional (Delft 3D) basado en la solución de las ecuaciones de Aguas Someras (Saint Venant) con el método de diferencias finitas, bajo condiciones normales y posibles escenarios de inundación. La metodología utilizada se basa en un protocolo de modelación, teniendo en cuenta la definición del tipo de modelo, del modelo conceptual del sistema, de la selección del código computacional y del diseño del modelo, asimismo, el análisis de sensibilidad, la calibración, y por último el establecimiento de escenarios críticos. A partir de los resultados obtenidos, se define que para la realización de simulaciones hidrodinámicas se debe tener en cuenta la extensión de la zona, e identificar si ésta cabe dentro de la escala de modelación hidrodinámica, se comprueba que la variabilidad del coeficiente de rugosidad de Manning no es muy influyente en los niveles de cuerpos de aguas someras y por último se verifican que los niveles obtenidos en el escenario de caudales cercanos a los máximos en el año 2010 (Escenario 6), presentan un buen ajuste a los niveles de huellas de inundación medidos por el IDEAM en las poblaciones de San Benito de Abad y Jegua.Anomalous conditions during El Niño-Southern Oscillation (ENSO) in its cold phase, during the years 2010-2011, have put in evidence the deficiencies in the ecorregion La Mojana regarding the planning and control of territory. Therefore, identifying the hydrodynamic behavior of the wetlands will help us to establish solutions for the sustainability of water resources, as well as the development of early warning systems for the population at risk condition. The main objective of this research is to evaluate the hydrodynamic behavior of the wetland Ciénaga de La Villa (Machado) that is part of La Mojana using the computational fluid dynamic platform DELFT 3D. This tool solves the Shallow Water Equations (Saint Venant) by means of the finite difference method in normal conditions and possible flooding scenarios. The methodology was based on a modelling protocol considering the model type, a conceptual model of the system, the selection of the software, and the model design. In addition to that, a sensitive analysis, calibration, and critical scenarios analyses are presented to assess the robustness of the simulations. From the results it was found that the correct definition of the computational domain is a critical step for the appropriate description of the scales of interest in the river-wetland interaction. It was also found that the Manning s roughness coefficient is not very influential in the levels of the system due to the low velocities present in the wetland. Finally we showed that the water levels obtained for the scenarios that are close the maximum levels reported in 2010 (Scenario 6) have a good fit compared to the level traces of flooding measured by IDEAM in the towns of San Benito Abad and Jegua.Magíster en Ingeniería CivilMaestrí

Impacts of individual tree species on carbon dynamics in a moist tropical forest environment

In the moist tropical forest biome, which cycles carbon (C) rapidly and stores huge amounts of C, the impacts of individual species on C balances are not well known. In one of the earliest replicated experimental sites for investigating growth of native tropical trees, we examined traits of tree species in relation to their effects on forest C balances, mechanisms of influence, and consequences for C sequestration. The monodominant stands, established in abandoned pasture in 1988 at La Selva Biological Station, Costa Rica, contained five species in a complete randomized block design. Native species were: Hieronyma alchorneoides, Pentaclethra macroloba, Virola koschnyi, and Vochysia guatemalensis. The exotic species was Pinus patula. By 16 years, the lack of differences among species in some attributes suggested strong abiotic control in this environment, where conditions are very favorable for growth. These attributes included aboveground net primary productivity (ANPP), averaging 11.7 Mg C·ha−1·yr−1 across species, and soil organic C (0–100 cm, 167 Mg C/ha). Other traits differed significantly, however, indicating some degree of biological control. In Vochysia plots, both aboveground biomass of 99 Mg C/ha, and belowground biomass of 20 Mg C/ha were 1.8 times that of Virola (P = 0.02 and 0.03, respectively). Differences among species in overstory biomass were not compensated by understory vegetation. Belowground NPP of 4.6 Mg C·ha−1·yr−1 in Hieronyma was 2.4 times that of Pinus (P \u3c 0.01). Partitioning of NPP to belowground components in Hieronyma was more than double that of Pinus (P = 0.03). The canopy turnover rate in Hieronyma was 42% faster than that of Virola (P \u3c 0.01). Carbon sequestration, highest in Vochysia (7.4 Mg C·ha−1·yr−1, P = 0.02), averaged 5.2 Mg C·ha−1·yr−1, close to the annual per capita fossil fuel use in the United States of 5.3 Mg C. Our results indicated that differences in species effects on forest C balances were related primarily to differences in growth rates, partitioning of C among biomass components, tissue turnover rates, and tissue chemistry. Inclusion of those biological attributes may be critical for robust modeling of C cycling across the moist tropical forest biome