De retibus socialibus et legibus momenti

Online Social Networks (OSNs) are a cutting edge topic. Almost everybody --users, marketers, brands, companies, and researchers-- is approaching OSNs to better understand them and take advantage of their benefits. Maybe one of the key concepts underlying OSNs is that of influence which is highly related, although not entirely identical, to those of popularity and centrality. Influence is, according to Merriam-Webster, "the capacity of causing an effect in indirect or intangible ways". Hence, in the context of OSNs, it has been proposed to analyze the clicks received by promoted URLs in order to check for any positive correlation between the number of visits and different "influence" scores. Such an evaluation methodology is used in this paper to compare a number of those techniques with a new method firstly described here. That new method is a simple and rather elegant solution which tackles with influence in OSNs by applying a physical metaphor.Comment: Changes made for third revision: Brief description of the dataset employed added to Introduction. Minor changes to the description of preparation of the bit.ly datasets. Minor changes to the captions of Tables 1 and 3. Brief addition in the Conclusions section (future line of work added). Added references 16 and 18. Some typos and grammar polishe

Copula selection models for non-Gaussian responses that are missing not at random

Missing not at random (MNAR) data poses key challenges for statistical inference because the model of interest is typically not identifiable without imposing further (e.g., distributional) assumptions. Sample selection models have been routinely used for handling MNAR by jointly modelling the outcome and selection variables assuming that these follow a bivariate normal distribution. Recent studies have advocated parametric selection model approaches, for example estimated by multiple imputation and maximum likelihood, that are more robust to departures from the normality assumption. However, the proposed methods have been mostly restricted to a specific joint distribution (e.g., bivariate t-distribution). This paper discusses a flexible copula-based selection approach (which accommodates a wide range of non-Gaussian outcome distributions and offers great flexibility in the choice of functional form specifications for both the outcome and selection equations) and proposes a flexible imputation procedure that generates plausible imputed values from the copula selection model. A simulation study characterises the relative performance of the copula model compared with the most commonly used selection models for estimating average treatment effects with MNAR data. We illustrate the methods in the REFLUX study, which evaluates the causal effect of laparoscopic surgery compared to usual medical management on long-term quality of life in patients with reflux disease. We provide software code for implementing the proposed copula framework using the R package GJRM

Quantitative proteomics reveals tissue-specific, infection-induced and species-specific neutrophil protein signatures

Neutrophils are one of the first responders to infection and are a key component of the innate immune system through their ability to phagocytose and kill invading pathogens, secrete antimicrobial molecules and produce extracellular traps. Neutrophils are produced in the bone marrow, circulate within the blood and upon immune challenge migrate to the site of infection. We wanted to understand whether this transition shapes the mouse neutrophil protein landscape, how the mouse neutrophil proteome is impacted by systemic infection and perform a comparative analysis of human and mouse neutrophils. Using quantitative mass spectrometry we reveal tissue-specific, infection-induced and species-specific neutrophil protein signatures. We show a high degree of proteomic conservation between mouse bone marrow, blood and peritoneal neutrophils, but also identify key differences in the molecules that these cells express for sensing and responding to their environment. Systemic infection triggers a change in the bone marrow neutrophil population with considerable impact on the core machinery for protein synthesis and DNA replication along with environmental sensors. We also reveal profound differences in mouse and human blood neutrophils, particularly their granule contents. Our proteomics data provides a valuable resource for understanding neutrophil function and phenotypes across species and model systems.</p

Desarrollo de un sistema de captura y formación de imágenes hiperespectrales mediante un UAV

Proyecto de Graduación (Licenciatura en Ingeniería Mecatrónica) Instituto Tecnológico de Costa Rica, Área Académica de Ingeniería Mecatrónica, 2018.En el presente documento se explica el desarrollo de un sistema capaz de capturar imágenes hiperespectrales mediante un vehículo aéreo no tripulado (UAV). Además se explica la teoría necesaria para comprender los conceptos que engloban la solución y los resultados obtenidos, así como las conclusiones y recomendaciones para futuros trabajos. También se mencionan algunos problemas relevantes que en algún momento detuvieron el avance de ciertas tareas y modificaron los planes de trabajo y las prioridades de este proyecto. El proyecto consistió de varias etapas de trabajo. Primero, se desarrolló un algoritmo para generar rutas o misiones para el UAV, con el n de que sean ejecutadas de forma autónoma. Para esto fue fundamental tomar en cuenta el método de captura de la cámara hiperespectral, ya que esto de finió las condiciones generales de vuelo. También se tomaron en cuenta parámetros que varían con cada vuelo, como el solape deseado entre las imágenes, altura, entre otros. Estos parámetros son insertados por la persona que ejecuta el algoritmo y con base en ellos son de nidos los puntos v a de cada ruta. Se hizo una guía para programar las rutas en el software Mission Planner, explicando los aspectos que se deben considerar al llevar una cámara hiperespectral en el UAV. Posteriormente, se llevó a cabo el montaje estructural del UAV, junto con las modificaciones necesarias para realizar los vuelos, así como la instalación de sensores y actuadores. Además se configuró el Pixhawk 2 con el n de controlar el UAV durante el vuelo. Después de esto, se planteó una estrategia para ejecutar una serie de pruebas de vuelo, como guía para futuros trabajos del grupo de investigación y que sea más fácil llegar a una versión final del proyecto, más allá de lo avanzado en el trabajo presentado en este documento. Esto con el n de no poner en riesgo el UAV, sus componentes internos y la cámara hiperespectral en las pruebas futuras. Luego como trabajo adicional, se hicieron correcciones en un estabilizador inercial (conocido comúnmente como "gimbal") que tuvo resultados pocos exitosos en trabajos previos realizados por el grupo de investigación. Por esta razón, en este trabajo se hicieron principalmente modificaciones mecánicas en las piezas y se propuso una solución al mal comportamiento del sistema de control empleado previamente en el estabilizador inercial. Se hicieron planos mecánicos del estabilizador corregido. Por ultimo se realizó un algoritmo para formar mapas hiperespectrales utilizando Matlab. Para esto fue necesario programar un método para unir los cubos hiperespectrales, teniendo en consideración la cámara hiperespectrales seleccionada. Es importante aclarar que todas estas etapas independientes se realizaron considerando una futura integración de las mismas. Por esta razón, los avances realizados en este trabajo y el desarrollo de cada una de las partes queda debidamente documentado para el seguimiento del proyecto por parte del Grupo Integrado de Ingeniería (GII), donde fue realizado.In this document, it is explained the development of a system capable of capturing hyperspectral images using an unmanned aerial vehicle (UAV). In addition, it is explained the necessary theory to comprehend concepts related with the solution, results, conclusions of this work and recommendations for the future. Finally, some relevant problems are mentioned, which stopped the progress of some tasks and modi ed the work plans and priorities of the project. The project consisted of many stages. First, it was developed an algorithm to create routes or missions for the UAV, which would be followed autonomously. The method used by the hyperspectral camera to capture images is very important, because it de ned the general ight conditions. Moreover, some parameters that change with every ight were also considered, such as the overlap between images, the height, and some others. These parameters are de ned by the person who executes the algorithm, so the points of the route (way points) can be calculated. A guide of how to create and program missions in the Mission Planner software was made, considering the aspects related with the hyperspectral camera and how it a ects the mission. Second, it was made the assembly of the UAV, making all the modi cations that it needed to y, like placing sensors and actuators. Furthermore, a Pixhawk 2 was con gured to control the UAV during the ight. After this, it was proposed a strategy to execute some ight tests as a guide for the investigation group. In this way, it will be easier to continue with this project in the future and get its nal version. The objective of this strategy is to avoid risks for the UAV and its internal components including the camera, while making the tests that were not made in this work. As additional task, some corrections were made on an inertial stabilizer (commonly known as "gimbal"), which had unsuccessful results in previous works made by the investigation group. For this reason, some mechanical modi cations were made, and it was proposed a solution to the control system that the stabilizer had. The respective mechanical drawings of the modi ed stabilizer were made. Finally, it was made an algorithm to create hyperspectral maps, using Matlab. Consequently, it was necessary to program a method to join the hyperspectral cubes, considering the selected hyperspectral camera. It's important to mention that all these independent stages were developed considering their integration in the future. For this reason, all the progress of this work and every stage is documented to allow the investigation group (Grupo Integrado de Ingeniería) to continue the project

Quantitative proteomics reveals tissue-specific, infection-induced and species-specific neutrophil protein signatures

Neutrophils are one of the first responders to infection and are a key component of the innate immune system through their ability to phagocytose and kill invading pathogens, secrete antimicrobial molecules and produce extracellular traps. Neutrophils are produced in the bone marrow, circulate within the blood and upon immune challenge migrate to the site of infection. We wanted to understand whether this transition shapes the mouse neutrophil protein landscape, how the mouse neutrophil proteome is impacted by systemic infection and perform a comparative analysis of human and mouse neutrophils. Using quantitative mass spectrometry we reveal tissue-specific, infection-induced and species-specific neutrophil protein signatures. We show a high degree of proteomic conservation between mouse bone marrow, blood and peritoneal neutrophils, but also identify key differences in the molecules that these cells express for sensing and responding to their environment. Systemic infection triggers a change in the bone marrow neutrophil population with considerable impact on the core machinery for protein synthesis and DNA replication along with environmental sensors. We also reveal profound differences in mouse and human blood neutrophils, particularly their granule contents. Our proteomics data provides a valuable resource for understanding neutrophil function and phenotypes across species and model systems.</p

Optimizing Spectronaut Search Parameters to Improve Data Quality with Minimal Proteome Coverage Reductions in DIA Analyses of Heterogeneous Samples

Data-independent acquisition has seen breakthroughs that enable comprehensive proteome profiling using short gradients. As the proteome coverage continues to increase, the quality of the data generated becomes much more relevant. Using Spectronaut, we show that the default search parameters can be easily optimized to minimize the occurrence of false positives across different samples. Using an immunological infection model system to demonstrate the impact of adjusting search settings, we analyzed Mus musculus macrophages and compared their proteome to macrophages spiked withCandida albicans. This experimental system enabled the identification of “false positives” as Candida albicans peptides and proteins should not be present in the Mus musculus-only samples. We show that adjusting the search parameters reduced “false positive” identifications by 89% at the peptide and protein level, thereby considerably increasing the quality of the data. We also show that these optimized parameters incurred a moderate cost, only reducing the overall number of “true positive” identifications across each biological replicate by &lt;6.7% at both the peptide and protein level. We believe the value of our updated search parameters extends beyond a two-organism analysis and would be of great value to any DIA experiment analyzing heterogeneous populations of cell types or tissues.</p

Optimizing Spectronaut Search Parameters to Improve Data Quality with Minimal Proteome Coverage Reductions in DIA Analyses of Heterogeneous Samples

Data-independent acquisition has seen breakthroughs that enable comprehensive proteome profiling using short gradients. As the proteome coverage continues to increase, the quality of the data generated becomes much more relevant. Using Spectronaut, we show that the default search parameters can be easily optimized to minimize the occurrence of false positives across different samples. Using an immunological infection model system to demonstrate the impact of adjusting search settings, we analyzed Mus musculus macrophages and compared their proteome to macrophages spiked withCandida albicans. This experimental system enabled the identification of “false positives” as Candida albicans peptides and proteins should not be present in the Mus musculus-only samples. We show that adjusting the search parameters reduced “false positive” identifications by 89% at the peptide and protein level, thereby considerably increasing the quality of the data. We also show that these optimized parameters incurred a moderate cost, only reducing the overall number of “true positive” identifications across each biological replicate by &lt;6.7% at both the peptide and protein level. We believe the value of our updated search parameters extends beyond a two-organism analysis and would be of great value to any DIA experiment analyzing heterogeneous populations of cell types or tissues.</p

Períodos de actividad y dieta de Dasyprocta punctata (Gray, 1842) (Rodentia; Dasyproctidae) en agroecosistemas con café, San Ramón, Costa Rica

La guatusa Dasyprocta punctata (Gray, 1842) es una especie clasificada como de población estable y presente en distintos hábitats, no obstante, sus hábitos (dieta, periodos de actividad y comportamiento) han sido poco descritos. La presente investigación se basa en determinar los hábitos D. punctata en agroecosistemas con café en Rincón de Mora, San Ramón, Alajuela, Costa Rica. Para ello, se colocaron cuatro cámaras trampa en sitios estratégicos (fuentes de alimentación, madrigueras, cuerpos de agua y transición con el bosque secundario). La revisión de los videos arrojó nuevos hábitos en cuanto a dieta que no se habían registrado para esta especie, incluyendo el consumo de Polyporus sp. Asimismo, se observó que el mayor periodo de actividad anual en el cafetal se da en la etapa fenológica con fruto, mientras que el periodo de actividad diario se amplió el espectro en horas de la noche. De igual forma, se registraron comportamientos ya identificados, donde uno de los más importantes es la dispersión de semillas.The guatusa Dasyprocta punctata (Gray, 1842) is a species classified as having a stable population and present in different habitats, however, its habits (diet, periods of activity and behavior) have been little described. This research is based on determining D. punctata habits in coffee agroecosystems in Rincón de Mora, San Ramón, Alajuela, Costa Rica. For this, four camera traps were placed in strategic places (food sources, burrows, creeks, and transition with the secondary forest). The review of the videos revealed new dietary habits that had not been recorded for this species, including the consumption of Polyporus sp. Likewise, it was observed that the greatest period of annual activity in the coffee plantation occurs in the phenological stage with fruit, while the period of daily activity broadened the spectrum in hours of the night. Similarly, already identified behaviors were recorded, where one of the most important is seed dispersal