Data Visualization, Dimensionality Reduction, and Data Alignment via Manifold Learning

The high dimensionality of modern data introduces significant challenges in descriptive and exploratory data analysis. These challenges gave rise to extensive work on dimensionality reduction and manifold learning aiming to provide low dimensional representations that preserve or uncover intrinsic patterns and structures in the data. In this thesis, we expand the current literature in manifold learning developing two methods called DIG (Dynamical Information Geometry) and GRAE (Geometry Regularized Autoencoders). DIG is a method capable of finding low-dimensional representations of high-frequency multivariate time series data, especially suited for visualization. GRAE is a general framework which splices the well-established machinery from kernel manifold learning methods to recover a sensitive geometry, alongside the parametric structure of autoencoders. Manifold learning can also be useful to study data collected from different measurement instruments, conditions, or protocols of the same underlying system. In such cases the data is acquired in a multi-domain representation. The last two Chapters of this thesis are devoted to two new methods capable of aligning multi-domain data, leveraging their geometric structure alongside limited common information. First, we present DTA (Diffusion Transport Alignment), a semi-supervised manifold alignment method that exploits prior one-to-one correspondence knowledge between distinct data views and finds an aligned common representation. And finally, we introduce MALI (Manifold Alignment with Label Information). Here we drop the one-to-one prior correspondences assumption, since in many scenarios such information can not be provided, either due to the nature of the experimental design, or it becomes extremely costly. Instead, MALI only needs side-information in the form of discrete labels/classes present in both domains

Huellas y devenir contable : construyendo las rutas del pensamiento contable

RESUMEN: El libro "Huellas y devenir contable", tiene como objetivo desarrollar una aproximación al estado del arte en las líneas de investigación del Grupo GICCO del Departamento de Ciencias Contables de la Universidad de Antioquia. Este texto expone los avances más notable en las diferentes líneas de investigación integradas desde tres ejes problémicos: Análisis contable (con sus líneas de investigación: costos y gestión, contabilidad y recursos públicos, análisis de procesos tributarios y contabilidad y finanzas), Desarrollo contable (que contiene las líneas de investigación: teoría contable, caracterización internacional de la contabilidad, educación contable, tecnología contable y desarrollo contable normativo) y control organizacional (contiene las líneas de investigación: control interno, procesos de auditoría y revisoría fiscal). La aproximación a las líneas de investigación se constituyen en un proceso que culmina con la construcción de los estados del arte, trabajo desarrollado por profesores y estudiantes integrantes de los grupos primarios de investigación; la aproximación a los ejes problémicos es un proceso de abstracción a partir de las líneas, trabajo desarrollado por el grupo integrador.Líneas de investigación contabl

Solving the Assignment of Customers to Trucks and Visit Days in a Periodic Routing Real-World Case

Abstract Introduction: This work proposes a model and two heuristic algorithms to assign customers to trucks and visit days as a first phase in the solution of a real-world routing problem, which is closely related to the PVRP (Periodic Vehicle Routing Problem), but a strategic decision of the company imposes the additional constraint that every customer must always be visited by the same truck. Methods: The proposed model will group the customers that are visited the same day by the same truck as close as possible by means of centroid-based clustering. The first proposed heuristic has a constructive stage and three underlying improvement heuristics, while the second uses an exact linear programming algorithm. Results: The algorithms are evaluated by instances taken from the literature and generated, taking into account the characteristics presented in the real-world case.Resumen Introducción: Este trabajo propone un modelo y dos algoritmos heurísticos para asignar clientes a camiones y días de visita como una primera fase en la solución de un problema de ruteo, que está estrechamente relacionado con el PVRP (Periodic Vehicle Routing Problem), aunque una decisión estratégica de la compañía impone la restricción adicional, de que cada cliente debe ser siempre visitado por el mismo camión. Métodos: el modelo propuesto tiene como objetivo agrupar a los clientes que son visitados el mismo día por el mismo camión lo más cerca posible por medio de clustering basado en centroides. La primera heurística propuesta tiene una etapa constructiva y tres heurísticas subyacentes de mejora, mientras que la segunda usa un algoritmo de programación lineal exacto. Resultados: los algoritmos son evaluados por instancias tomadas de la literatura y generadas, teniendo en cuenta las características presentadas en el caso real abordado

Inclusive recycling: towards a circular economy in Colombia

Este libro aborda el proceso de reciclaje como un eje primordial en la búsqueda de sustentabilidad cuyo compromiso es disminuir el impacto ambiental del desarrollo económico. En Colombia el reciclaje constituye una oportunidad en los procesos económicos, pero también en la generación de conciencia en la protección del medio ambiente. En primer lugar, se realiza un desarrollo conceptual sobre la economía circular. Posteriormente, se analiza el tema desde una perspectiva práctica en las cadenas de producción y consumo, y entendiendo el rol del reciclaje como nodo central de los procesos productivos. En tercer lugar, se aborda el contexto de Colombia, con un diagnóstico territorial y normativo; y un análisis detallado de las estaciones de clasificación y aprovechamiento (eca), unidad básica del modelo de reciclaje inclusivo en el país. Y, finalmente, se exploran los procesos tecnológicos que recientemente han impulsado mejoras en los procesos de reciclajeThis book addresses the recycling process as a primary axis in the search for sustainability, which is committed to reducing the environmental impact of economic development. In Colombia, recycling constitutes an opportunity in economic processes, as well as in generating awareness towards the protection of the environment. First, the notion of circular economy is developed conceptually. Subsequently, the subject is analyzed from a practical perspective on production and consumption chains, understanding the role of recycling as the central node of production processes. Third, the context of Colombia is addressed, with a territorial and normative diagnosis, as well as a detailed analysis of the stations of sorting and utilization (eca, for its initials in Spanish), basic units of the inclusive recycling model in the country. And, finally, technological processes are explored, which have driven recent improvements in recycling processe

Divulgación Científica No.4

En las instituciones encargadas de adelantar proyectos de investigación, como es el caso de la universidad, debemos reflexionar sobre lo que hacemos y sus implicaciones, de tal forma que encontremos claves para propiciar, desde nuestros saberes, agentes dinamizadores que animen la discusión, el debate y la comparación. Lo anterior con el enfoque de proponer caminos y soluciones para problemas actuales que nos aquejan como individuos. Las distintas búsquedas que hacemos apuntan a contribuir a la construcción de mejores sociedades, y la investigación es una valiosa herramienta con a que contamos para lograrlo. Es necesario entender la investigación como un agente que permite y propicia cambios.In the institutions in charge of carrying out research projects, such as the university, we must reflect on what we do and its implications, in such a way that we find keys to promote, from our knowledge, dynamic agents that encourage discussion, debate and the comparison. The above with the focus of proposing paths and solutions for current problems that afflict us as individuals. The different searches that we do aim to contribute to the construction of better societies, and research is a valuable tool that we have to achieve it. It is necessary to understand research as an agent that allows and promotes changes

Delayed colorectal cancer care during covid-19 pandemic (decor-19). Global perspective from an international survey

Background The widespread nature of coronavirus disease 2019 (COVID-19) has been unprecedented. We sought to analyze its global impact with a survey on colorectal cancer (CRC) care during the pandemic. Methods The impact of COVID-19 on preoperative assessment, elective surgery, and postoperative management of CRC patients was explored by a 35-item survey, which was distributed worldwide to members of surgical societies with an interest in CRC care. Respondents were divided into two comparator groups: 1) ‘delay’ group: CRC care affected by the pandemic; 2) ‘no delay’ group: unaltered CRC practice. Results A total of 1,051 respondents from 84 countries completed the survey. No substantial differences in demographics were found between the ‘delay’ (745, 70.9%) and ‘no delay’ (306, 29.1%) groups. Suspension of multidisciplinary team meetings, staff members quarantined or relocated to COVID-19 units, units fully dedicated to COVID-19 care, personal protective equipment not readily available were factors significantly associated to delays in endoscopy, radiology, surgery, histopathology and prolonged chemoradiation therapy-to-surgery intervals. In the ‘delay’ group, 48.9% of respondents reported a change in the initial surgical plan and 26.3% reported a shift from elective to urgent operations. Recovery of CRC care was associated with the status of the outbreak. Practicing in COVID-free units, no change in operative slots and staff members not relocated to COVID-19 units were statistically associated with unaltered CRC care in the ‘no delay’ group, while the geographical distribution was not. Conclusions Global changes in diagnostic and therapeutic CRC practices were evident. Changes were associated with differences in health-care delivery systems, hospital’s preparedness, resources availability, and local COVID-19 prevalence rather than geographical factors. Strategic planning is required to optimize CRC care