Reducción de dimensiones: revisión y aplicaciones en clasificación automática

En la actualidad es habitual encontrar conjuntos de datos de alta dimensión. Este tipo de datos son difíciles de interpretar y presentan problemas como entrada a algoritmos de clasificación debido a la maldición de la dimensionalidad. Una manera de mejorar estos aspectos es la aplicación de métodos de reducción de la dimensión. Este trabajo tiene como objetivo analizar y comparar un subconjunto de los métodos de reducción de dimensión existentes. Además, se hace una evaluación de los mismos tanto de una manera aislada mediante diferentes medidas de calidad como por su impacto en diferentes métodos de clasificación. Ambas evaluaciones se realizan sobre un conjunto de datos de referencia como es MNIST. De una manera más concreta, se han evaluado los métodos de reducción usando medidas cuantitativas para medir la conservación de las propiedades locales y globables de los datos. Posteriormente se han comparado métodos de clasificación entrenados en un conjunto de datos reducido con métodos entrenados con los datos originales. Los resultados obtenidos muestran que cual es el mejor método de reducción de dimensión depende de nuestro objetivo (visualización o preprocesamiento). Además se comprueba que la reducción de dimensión es una estrategia viable para mejorar el comportamiento de un clasificador o para reducir el coste de entrenarlo, almacenarlo o usarlo.Nowadays it is common to find high dimensional data sets. This type of data is difficult to interpret and present problems as input to classification algorithms due to the curse of dimensionality. One way to improve these aspects is the application of dimension reduction methods This work aims to analyze and compare a subset of existing dimensional reduction methods. In addition, they are evaluated both in an isolated way by different quality measures and by their impact on different classification methods. Both evaluations are carried out on a reference data set such as MNIST. More specifically, reduction methods have been evaluated using quantitative measures to measure the conservation of local and global properties of the data. Subsequently, classification methods trained on a reduced data set have been compared with methods trained on the original data. The results obtained show that which is the best dimension reduction method depends on our objective (visualization or pre-processing). In addition, it is proven that dimensional reduction is a viable strategy to improve the behavior of a classifier or to reduce the cost of training, storing or using it.Grado en Ingeniería Informátic

Problemas de diseño de redes con restricciones de saltos (hop constraints)

En el presente documento se expondrán diferentes métodos para dar solución al problema del mínimo árbol generador con restricciones de salto (HMST, Hopconstrained minimun spanning tree problem). Se afrontará su resolución tanto de manera exacta como aproximada búscando siempre la obtención de buenas soluciones en tiempos razonables.Grado en Estadístic

Análisis de datos selvícolas con R

La cuantificación de la selvicultura permite medir y comparar los tratamientos selvícolas y sus efectos sobre los bosques. Así, dos conceptos a menudo distantes para la mayoría de las personas como son los bosques y los números pueden hacernos reflexionar sobre diversos aspectos de interés para la gestión de los bosques. Entre otras preguntas que podemos hacernos destacan dos: 1. ¿Tiene sentido cuantificar los procesos que ocurren en los bosques? 2. ¿Qué aporta la cuantificación de los procesos forestales a la toma de decisiones? Si la respuesta a la primera pregunta es sí y a la segunda podemos responder diciendo que lo que aporta la cuantificación es relevante para la selvicultura, entonces debemos disponer de herramientas avanzadas para el análisis forestal. Una de estas herramientas es el programa informático de análisis estadístico R. Con este manual se pretende dotar de una herramienta de apoyo a las clases de grado y máster relacionadas con los aspectos cuantitativos de la selvicultura.Departamento de Producción Vegetal y Recursos Forestale

Alimentación y actividad física como factores determinantes del estado nutricional de los escolares de seis a nueve años

Tesis (Profesor de Educación Física para la Enseñanza Básica, Licenciado en Educación)En el siguiente documento se detalla una investigación realizada por un grupo de estudiantes de la Universidad Andrés Bello para optar al título de Profesor de Educación Física para la Enseñanza General Básica. La investigación está orientada a determinar cómo los factores de alimentación y actividad física influyen en el estado nutricional de niños entre seis a nueve años de edad. Para esto, se interviene el Colegio Saint Andrew ubicado en la comuna de Las Condes de la Región Metropolitana y el Colegio San Lorenzo ubicado en el pueblo de Coya en la comuna de Machalí de la Región del Libertador General Bernardo O´Higgins de Chile. En dichos establecimientos se seleccionan al azar y con previo consentimiento un total de 64 sujetos, los que serán sometidos a distintas pruebas y mediciones. Estas pruebas son el test de caminata en seis minutos, encuesta alimenticia, dinamometría de brazo y mediciones antropométricas de pliegues subcutáneos. A través de los resultados que van a entregar estas pruebas y mediciones, se espera obtener valores que determinen en qué nivel afectan los factores de alimentación y sedentarismo en el nivel nutricional de un sujeto.The following document details an investigation carried out by a group of students of the Andrés Bello University to qualify for the title of Professor of Physical Education for Basic General Education. The research is aimed at determining how the factors of food and physical activity influence the nutritional status of children between six to nine years of age. For this, Saint Andrew College is located in the Las Condes district of the Metropolitan Region and the San Lorenzo School located in the town of Coya in the Machalí district of the Region of Libertador General Bernardo O'Higgins of Chile. In these establishments, a total of 64 subjects are selected at random and with prior consent, who will be subjected to different tests and measurements. These tests are the six-minute walk test, food survey, arm dynamometry and anthropometric measurements of subcutaneous folds. Through the results that are going to deliver these tests and measurements, it is expected to obtain values that determine in which level they affect the factors of feeding and sedentarism in the nutritional level of a subjec

Role of age and comorbidities in mortality of patients with infective endocarditis

[Purpose]: The aim of this study was to analyse the characteristics of patients with IE in three groups of age and to assess the ability of age and the Charlson Comorbidity Index (CCI) to predict mortality. [Methods]: Prospective cohort study of all patients with IE included in the GAMES Spanish database between 2008 and 2015.Patients were stratified into three age groups:<65 years,65 to 80 years,and ≥ 80 years.The area under the receiver-operating characteristic (AUROC) curve was calculated to quantify the diagnostic accuracy of the CCI to predict mortality risk. [Results]: A total of 3120 patients with IE (1327 < 65 years;1291 65-80 years;502 ≥ 80 years) were enrolled.Fever and heart failure were the most common presentations of IE, with no differences among age groups.Patients ≥80 years who underwent surgery were significantly lower compared with other age groups (14.3%,65 years; 20.5%,65-79 years; 31.3%,≥80 years). In-hospital mortality was lower in the <65-year group (20.3%,<65 years;30.1%,65-79 years;34.7%,≥80 years;p < 0.001) as well as 1-year mortality (3.2%, <65 years; 5.5%, 65-80 years;7.6%,≥80 years; p = 0.003).Independent predictors of mortality were age ≥ 80 years (hazard ratio [HR]:2.78;95% confidence interval [CI]:2.32–3.34), CCI ≥ 3 (HR:1.62; 95% CI:1.39–1.88),and non-performed surgery (HR:1.64;95% CI:11.16–1.58).When the three age groups were compared,the AUROC curve for CCI was significantly larger for patients aged <65 years(p < 0.001) for both in-hospital and 1-year mortality. [Conclusion]: There were no differences in the clinical presentation of IE between the groups. Age ≥ 80 years, high comorbidity (measured by CCI),and non-performance of surgery were independent predictors of mortality in patients with IE.CCI could help to identify those patients with IE and surgical indication who present a lower risk of in-hospital and 1-year mortality after surgery, especially in the <65-year group

Clonal chromosomal mosaicism and loss of chromosome Y in elderly men increase vulnerability for SARS-CoV-2

The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, COVID-19) had an estimated overall case fatality ratio of 1.38% (pre-vaccination), being 53% higher in males and increasing exponentially with age. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, we found 133 cases (1.42%) with detectable clonal mosaicism for chromosome alterations (mCA) and 226 males (5.08%) with acquired loss of chromosome Y (LOY). Individuals with clonal mosaic events (mCA and/or LOY) showed a 54% increase in the risk of COVID-19 lethality. LOY is associated with transcriptomic biomarkers of immune dysfunction, pro-coagulation activity and cardiovascular risk. Interferon-induced genes involved in the initial immune response to SARS-CoV-2 are also down-regulated in LOY. Thus, mCA and LOY underlie at least part of the sex-biased severity and mortality of COVID-19 in aging patients. Given its potential therapeutic and prognostic relevance, evaluation of clonal mosaicism should be implemented as biomarker of COVID-19 severity in elderly people. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, individuals with clonal mosaic events (clonal mosaicism for chromosome alterations and/or loss of chromosome Y) showed an increased risk of COVID-19 lethality

The Helicobacter pylori Genome Project : insights into H. pylori population structure from analysis of a worldwide collection of complete genomes

Helicobacter pylori, a dominant member of the gastric microbiota, shares co-evolutionary history with humans. This has led to the development of genetically distinct H. pylori subpopulations associated with the geographic origin of the host and with differential gastric disease risk. Here, we provide insights into H. pylori population structure as a part of the Helicobacter pylori Genome Project (HpGP), a multi-disciplinary initiative aimed at elucidating H. pylori pathogenesis and identifying new therapeutic targets. We collected 1011 well-characterized clinical strains from 50 countries and generated high-quality genome sequences. We analysed core genome diversity and population structure of the HpGP dataset and 255 worldwide reference genomes to outline the ancestral contribution to Eurasian, African, and American populations. We found evidence of substantial contribution of population hpNorthAsia and subpopulation hspUral in Northern European H. pylori. The genomes of H. pylori isolated from northern and southern Indigenous Americans differed in that bacteria isolated in northern Indigenous communities were more similar to North Asian H. pylori while the southern had higher relatedness to hpEastAsia. Notably, we also found a highly clonal yet geographically dispersed North American subpopulation, which is negative for the cag pathogenicity island, and present in 7% of sequenced US genomes. We expect the HpGP dataset and the corresponding strains to become a major asset for H. pylori genomics

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Preliminary Evidence for Internal Structure, Sensitivity, and Specificity of a Brief PTSD and Complex PTSD Measure in Adolescents

Early detection of trauma-related psychopathology is fundamental for preventing symptom escalation in adolescents, and this strategy can be carried out by developing accurate measures. The aim of this study is to provide preliminary evidence for the internal structure, construct validity, reliability, sensitivity, and specificity of a brief screening instrument for posttraumatic stress disorder (PTSD) and complex PTSD (C-PTSD) in general population adolescents. 1,501 Chilean adolescents participated by responding to the Brief PTSD scale (BPTSD) along with a battery of additional questionnaires. The internal structure of the eight-item BPTSD was assessed through exploratory and confirmatory factor analyses, while criterion validity was assessed through receiver-operating characteristic (ROC) curves. Confirmatory factor analysis (CFA) demonstrated a two-dimensional internal structure that is in accordance with literature regarding C-PTSD. Our results suggest that BPTSD may measure PTSD with complex features rather than C-PTSD. The scale showed adequate reliability, and criterion validity. The BPTSD is a brief, reliable, and simplyworded measure for PTSD symptoms and C-PTSD features in adolescents