Search results for "Bayes"

Defining classifier regions for WSD ensembles using word space features

2006

Based on recent evaluation of word sense disambiguation (WSD) systems [10], disambiguation methods have reached a standstill. In [10] we showed that it is possible to predict the best system for target word using word features and that using this 'optimal ensembling method' more accurate WSD ensembles can be built (3-5% over Senseval state of the art systems with the same amount of possible potential remaining). In the interest of developing if more accurate ensembles, w e here define the strong regions for three popular and effective classifiers used for WSD task (Naive Bayes – NB, Support Vector Machine – SVM, Decision Rules – D) using word features (word grain, amount of positive and neg…

Efficient Online Laplacian Eigenmap Computation for Dimensionality Reduction in Molecular Phylogeny via Optimisation on the Sphere

2019

Reconstructing the phylogeny of large groups of large divergent genomes remains a difficult problem to solve, whatever the methods considered. Methods based on distance matrices are blocked due to the calculation of these matrices that is impossible in practice, when Bayesian inference or maximum likelihood methods presuppose multiple alignment of the genomes, which is itself difficult to achieve if precision is required. In this paper, we propose to calculate new distances for randomly selected couples of species over iterations, and then to map the biological sequences in a space of small dimension based on the partial knowledge of this genome similarity matrix. This mapping is then used …

Environmental risk factors of airborne viral transmission: Humidity, Influenza and SARS-CoV-2 in the Netherlands

2020

AbstractObjectiveThe relationship between specific humidity and influenza/SARS-CoV-2 in the Netherlands is evaluated over time and at regional level.DesignParametric and non-parametric correlation coefficients are calculated to quantify the relationship between humidity and influenza, using five years of weekly data. Bayesian spatio-temporal models—with a Poisson and a Gaussian likelihood—are estimated to find the relationship between regional humidity and the daily cases of SARS-CoV-2 in the municipalities and provinces of the Netherlands.ResultsAn inverse (negative) relationship is observed between specific humidity and the incidence of influenza between 2015 and 2019. The space-time anal…

Distributed channel prediction for multi-agent systems

2017

Los sistemas multiagente (MAS) se comunican a través de una red inalámbrica para coordinar sus acciones e informar sobre el estado de su misión. La conectividad y el rendimiento del sistema pueden mejorarse mediante la predicción de la ganancia del canal. Presentamos un esquema basado en regresión de procesos gaussianos (GPR) distribuidos para predecir el canal inalámbrico en términos de la potencia recibida en el MAS. El esquema combina una máquina de comité bayesiano con un esquema de consenso medio, distribuyendo así no sólo la memoria sino también la carga computacional y de comunicación. A través de simulaciones de Monte Carlo, demostramos el rendimiento del GPR propuesto. RACHEL TEC20…

Particle identification in ALICE: a Bayesian approach

2016

We present a Bayesian approach to particle identification (PID) within the ALICE experiment. The aim is to more effectively combine the particle identification capabilities of its various detectors. After a brief explanation of the adopted methodology and formalism, the performance of the Bayesian PID approach for charged pions, kaons and protons in the central barrel of ALICE is studied. PID is performed via measurements of specific energy loss ($\mathrm{d}E/\mathrm{d}x$) and time-of-flight. PID efficiencies and misidentification probabilities are extracted and compared with Monte Carlo simulations using high-purity samples of identified particles in the decay channels ${\rm K}^0_S \righta…

Species distribution modelling in fisheries science

2017

Latest fisheries directives propose adopting an ecosystem approach to manage fisheries \citep{FAO-EAFM}. Such an approach aims to protect important ecosystems based on the principle that healthy ecosystems produce more and thus enhance sustainability. Unfortunately, quantifying the importance of an ecosystem is a difficult task to do due the immense number of interactions involved in marine systems. This PhD dissertation relies on the fact that good fisheries distribution maps could play a very important role as they allow a visual and intuitive assessment of different marine areas. Unfortunately, the limited amount of data available and the inherent difficulties of modelling fishery data h…

New insights in Bayesian Survival Analysis in Ecology

2020

La fauna silvestre está asediada. Y ésta no es solo una frase impactante con la que empezar una tesis, tristemente, es una realidad. En el último siglo, muchas especies han disminuido drásticamente, mientras que otras afrontan su extinción debido, principalmente, a los rápidos cambios (y a gran escala) ocurridos tanto en hábitats como en ecosistemas. El cambio climático, las especies invasoras, la caza ilegal y la sobrepesca son sólo algunas de las principales amenazas que afectan a las poblaciones de animales silvestres en la actualidad. Para abordar este problema, se requiere de un compromiso a todos los niveles, desde las comunidades locales hasta los gobiernos, pasando por los expertos,…

Spatio temporal modeling of species distribution

2019

The aim of this thesis is study spatial distribution of different groups from different perspectives and to analyse the different approaches to this problem. We move away from the classical approach, commonly used by ecologists, to more complex solutions, already applied in several disciplines. We are focused in applying advanced modelling techniques in order to understand species distribution and species behaviour and the relationships between them and environmental factors and have used first the most common models applied in ecology to move then to more advanced and complex perspectives. From a general perspective and comparing the different models applied during the process, from MaxEnt…

Importance of proper conduct of clinical trials

2021

Genetic structure and differentiation from early bronze age in the mediterranean island of sicily: Insights from ancient mitochondrial genomes

2022

Sicily is one of the main islands of the Mediterranean Sea, and it is characterized by a variety of archaeological records, material culture and traditions, reflecting the history of migrations and populations’ interaction since its first colonization, during the Paleolithic. These deep and complex demographic and cultural dynamics should have affected the genomic landscape of Sicily at different levels; however, the relative impact of these migrations on the genomic structure and differentiation within the island remains largely unknown. The available Sicilian modern genetic data gave a picture of the current genetic structure, but the paucity of ancient data did not allow so far to make p…