Clustering Analysis within Text Classification Techniques

The paper represents a personal approach upon the main applications of classification which are presented in the area of knowledge based society by means of methods and techniques widely spread in the literature. Text classification is underlined in chapter two where the main techniques used are described, along with an integrated taxonomy. The transition is made through the concept of spatial representation. Having the elementary elements of geometry and the artificial intelligence analysis, spatial representation models are presented. Using a parallel approach, spatial dimension is introduced in the process of classification. The main clustering methods are described in an aggregated taxonomy. For an example, spam and ham words are clustered and spatial represented, when the concepts of spam, ham and common and linkage word are presented and explained in the xOy space representation.Knowledge Societies, Text Classification, Spatial Representation, Artificial Intelligence, Clustering Analysis, Spam Filtering

Knowledge discovery process for description of spatially referenced clusters

Spatial clustering is an important field of spatial data mining and knowledge discovery that serves to partition a spatial data set to obtain disjoint subsets with spatial elements that are similar to each other. Existing algorithms can be used to perform three types of cluster analyses, including clustering of spatial points, regionalization and point pattern analysis. However, all these existing methods do not provide a description of the discovered spatial clusters, which is useful for decision making in many different fields. This work proposes a knowledge discovery process for the description of spatially referenced clusters that uses decision tree learning algorithms. Two proofs of concept of the proposed process using different spatial clustering algorithm on real data are also provided.Facultad de Informátic

Knowledge discovery process for description of spatially referenced clusters

Spatial clustering is an important field of spatial data mining and knowledge discovery that serves to partition a spatial data set to obtain disjoint subsets with spatial elements that are similar to each other. Existing algorithms can be used to perform three types of cluster analyses, including clustering of spatial points, regionalization and point pattern analysis. However, all these existing methods do not provide a description of the discovered spatial clusters, which is useful for decision making in many different fields. This work proposes a knowledge discovery process for the description of spatially referenced clusters that uses decision tree learning algorithms. Two proofs of concept of the proposed process using different spatial clustering algorithm on real data are also provided.Facultad de Informátic

Spatial Unemployment Differentials in Colombia

This paper studies the geographic distribution of unemployment rates in Colombian urban areas. It introduces measures of spatial correlation and spatial econometric techniques to analyze the dependence in local unemployment rates across municipalities. Results suggest that Colombian municipalities have experienced a polarization process between 1993 and 2005, as municipalities' unemployment rates have followed different evolutions relative to the National average. This process has been accompanied by the creation of unemployment clusters, that is to say, municipalities had very similar unemployment outcomes to those of their neighbors. This analysis uses a spatial Durbin model to explore the influence of various factors in determining differences in regional unemployment rates. According to our findings differences in labor demand, immigration rates, and urbanization are factors behind observed municipal unemployment disparities.local labor markets, unemployment di erential, polarization, clustering, spatial econometrics, spatial Durbin model

Model-based deep autoencoders for clustering single-cell RNA sequencing data with side information

Clustering analysis has been conducted extensively in single-cell RNA sequencing (scRNA-seq) studies. scRNA-seq can profile tens of thousands of genes\u27 activities within a single cell. Thousands or tens of thousands of cells can be captured simultaneously in a typical scRNA-seq experiment. Biologists would like to cluster these cells for exploring and elucidating cell types or subtypes. Numerous methods have been designed for clustering scRNA-seq data. Yet, single-cell technologies develop so fast in the past few years that those existing methods do not catch up with these rapid changes and fail to fully fulfil their potential. For instance, besides profiling transcription expression levels of genes, recent single-cell technologies can capture other auxiliary information at the single-cell level, such as protein expression (multi-omics scRNA-seq) and cells\u27 spatial location information (spatial-resolved scRNA-seq). Most existing clustering methods for scRNA-seq are performed in an unsupervised manner and fail to exploit available side information for optimizing clustering performance. This dissertation focuses on developing novel computational methods for clustering scRNA-seq data. The basic models are built on a deep autoencoder (AE) framework, which is coupled with a ZINB (zero-inflated negative binomial) loss to characterize the zero-inflated and over-dispersed scRNA-seq count data. To integrate multi-omics scRNA-seq data, a multimodal autoencoder (MAE) is employed. It applies one encoder for the multimodal inputs and two decoders for reconstructing each omics of data. This model is named scMDC (Single-Cell Multi-omics Deep Clustering). Besides, it is expected that cells in spatial proximity tend to be of the same cell types. To exploit cellular spatial information available for spatial-resolved scRNA-seq (sp-scRNA-seq) data, a novel model, DSSC (Deep Spatial-constrained Single-cell Clustering), is developed. DSSC integrates the spatial information of cells into the clustering process by two steps: 1) the spatial information is encoded by using a graphical neural network model; 2) cell-to-cell constraints are built based on the spatially expression pattern of the marker genes and added in the model to guide the clustering process. DSSC is the first model which can utilize the information from both the spatial coordinates and the marker genes to guide the cell/spot clustering. For both scMDC and DSSC, a clustering loss is optimized on the bottleneck layer of autoencoder along with the learning of feature representation. Extensive experiments on both simulated and real datasets demonstrate that scMDC and DSSC boost clustering performance significantly while costing no extra time and space during the training process. These models hold great promise as valuable tools for harnessing the full potential of state-of-the-art single-cell data

Has concentration evolved similarly in manufacturing and services? A sensitivity analysis.

Our first objective is to compare the degree of concentration in manufacturing and services, with special emphasis on its evolution in these two sectors, using a sensitivity analysis for different concentration indices and different geographic units of analysis: municipalities and local labour systems of Catalonia in 1991 and 2001. Most concentration measures fail to consider the space in which a particular municipality is located. Our second objective is to overcome this problem by applying two different techniques: by using a clustering measure, and by analysing whether the location quotients computed for each municipality and sector present some kind of spatial autocorrelation process. We take special account of the differences in patterns of concentration according to the technological level of the sectors.Geographic concentration, Manufacturing, Services, Local Labour Systems, Spatial Econometrics.