Model Selection in Summary Evaluation

A difficulty in the design of automated text summarization algorithms is in the objective evaluation. Viewing summarization as a tradeoff between length and information content, we introduce a technique based on a hierarchy of classifiers to rank, through model selection, different summarization methods. This summary evaluation technique allows for broader comparison of summarization methods than the traditional techniques of summary evaluation. We present an empirical study of two simple, albeit widely used, summarization methods that shows the different usages of this automated task-based evaluation system and confirms the results obtained with human-based evaluation methods over smaller corpora.

Feature Selection for Face Detection

We present a new method to select features for a face detection system using Support Vector Machines (SVMs). In the first step we reduce the dimensionality of the input space by projecting the data into a subset of eigenvectors. The dimension of the subset is determined by a classification criterion based on minimizing a bound on the expected error probability of an SVM. In the second step we select features from the SVM feature space by removing those that have low contributions to the decision function of the SVM.

Sales restriction, quality selection and the mode of competition

A regulator imposing “sales restrictions” on firms competing in oligopolistic markets may enhance quality provision by the firms. Moreover, for most restrictions levels, the impact on quality selection is invariant to the mode of competition

Hardy-Weinberg Equilibrium and the Ternary Plot

The Hardy-Weinberg law, formulated about 100 years ago, states that under certain assumptions, the three genotypes AA, AB and BB at a bi-allelic locus are expected to occur in the proportions p2, 2pq, and q2 respectively, where p is the allele frequency of A, and q = 1-p. There are many statistical tests being used to check whether empirical marker data obeys the Hardy-Weinberg principle. Among these are the classical xi-square test (with or without continuity correction), the likelihood ratio test, Fisher's Exact test, and exact tests in combination with Monte Carlo and Markov Chain algorithms. Tests for Hardy-Weinberg equilibrium (HWE) are numerical in nature, requiring the computation of a test statistic and a p-value. There is however, ample space for the use of graphics in HWE tests, in particular for the ternary plot. Nowadays, many genetical studies are using genetical markers known as Single Nucleotide Polymorphisms (SNPs). SNP data comes in the form of counts, but from the counts one typically computes genotype frequencies and allele frequencies. These frequencies satisfy the unit-sum constraint, and their analysis therefore falls within the realm of compositional data analysis (Aitchison, 1986). SNPs are usually bi-allelic, which implies that the genotype frequencies can be adequately represented in a ternary plot. Compositions that are in exact HWE describe a parabola in the ternary plot. Compositions for which HWE cannot be rejected in a statistical test are typically “close" to the parabola, whereas compositions that differ significantly from HWE are “far". By rewriting the statistics used to test for HWE in terms of heterozygote frequencies, acceptance regions for HWE can be obtained that can be depicted in the ternary plot. This way, compositions can be tested for HWE purely on the basis of their position in the ternary plot (Graffelman & Morales, 2008). This leads to nice graphical representations where large numbers of SNPs can be tested for HWE in a single graph. Several examples of graphical tests for HWE (implemented in R software), will be shown, using SNP data from different human populations

Use of decision trees in colour feature selection: application to object recognition in outdoor scenes

A new method for the automated selection of colour features is described. The algorithm consists of two stages of processing. In the first, a complete set of colour features is calculated for every object of interest in an image. In the second stage, each object is mapped into several n-dimensional feature spaces in order to select the feature set with the smallest variables able to discriminate the remaining objects. The evaluation of the discrimination power for each concrete subset of features is performed by means of decision trees composed of linear discrimination functions. This method can provide valuable help in outdoor scene analysis where no colour space has been demonstrated as being the most suitable. Experiment results recognizing objects in outdoor scenes are reported

Enhanced Model Selection for motion segmentation

In this paper a novel rank estimation technique for trajectories motion segmentation within the Local Subspace Affinity (LSA) framework is presented. This technique, called Enhanced Model Selection (EMS), is based on the relationship between the estimated rank of the trajectory matrix and the affinity matrix built by LSA. The results on synthetic and real data show that without any a priori knowledge, EMS automatically provides an accurate and robust rank estimation, improving the accuracy of the final motion segmentation

Citation auctions as a method to improve selection of scientific papers

This paper describes the basis of citation auctions as a new approach to selecting scientific papers for publication. Our main idea is to use an auction for selecting papers for publication through - differently from the state of the art - bids that consist of the number of citations that a scientist expects to receive if the paper is published. Hence, a citation auction is the selection process itself, and no reviewers are involved. The benefits of the proposed approach are two-fold. First, the cost of refereeing will be either totally eliminated or significantly reduced, because the process of citation auction does not need prior understanding of the paper's content to judge the quality of its contribution. Additionally, the method will not prejudge the content of the paper, so it will increase the openness of publications to new ideas. Second, scientists will be much more committed to the quality of their papers, paying close attention to distributing and explaining their papers in detail to maximize the number of citations that the paper receives. Sample analyses of the number of citations collected in papers published in years 1999-2004 for one journal, and in years 2003-2005 for a series of conferences (in a totally different discipline), via Google scholar, are provided. Finally, a simple simulation of an auction is given to outline the behaviour of the citation auction approach

Selection of UAS student presentations from June 2009

Selection of UAS student presentations from June 2009

El sistema multifondos de pensiones colombiano bajo las nuevas teorías del comportamiento financiero

En Colombia, después de casi dos décadas de la creación del régimen de cuentas privadas, se implementó una reforma donde se pasa de un sistema con un unico fondo a uno multifondos. Este tipo de reformas se vienen implementando en diferentes paises europeos y de Latino America. A la luz de las teorías clásicas dicha reforma trae mejoras en el bienestar de los individuos; sin embargo, la literatura sobre las nuevas teorías del comportamiento sugiere que los individuos no siempre toman decisiones que están de acuerdo con los supuestos de las teorías clásicas. Este trabajo estudia esta reforma en Colombia bajo algunas de las teorías del comportamiento financiero. Se encuentra que aún cuando el afiliado se quede en la opción default , o actúe con aversión a la pérdida, va a obtener valores en sus cuentas privadas mayores a las que obtendría con un sistema de un único fondo.

El sistema multifondos de pensiones colombiano bajo las nuevas teorías del comportamiento financiero

En Colombia, después de casi dos décadas de la creación del régimen de cuentas privadas, se implementó una reforma donde se pasa de un sistema con un único fondo a uno multifondos. Este tipo de reformas se vienen implementando en diferentes países europeos y de Latino América. A la luz de las teorías clásicas dicha reforma trae mejoras en el bienestar de los individuos; sin embargo, la literatura sobre las nuevas teorías del comportamiento sugiere que los individuos no siempre toman decisiones que están de acuerdo con los supuestos de las teorías clásicas. Este trabajo estudia esta reforma en Colombia bajo algunas de las teorías del comportamiento financiero. Se encuentra que aún cuando el afiliado se quede en la opción default , o actúe con aversión a la pérdida, va a obtener valores en sus cuentas privadas mayores a las que obtendría con un sistema de un único fondo.

"Genetic Diversity and Selection in Three Plasmodium vivax Merozoite Surface Protein 7 (Pvmsp-7) Genes in a Colombian Population"

A completely effective vaccine for malaria (one of the major infectious diseases worldwide) is not yet available; different membrane proteins involved in parasite-host interactions have been proposed as candidates for designing it. It has been found that proteins encoded by the merozoite surface protein (msp)-7 multigene family are antibody targets in natural infection; the nucleotide diversity of three Pvmsp-7 genes was thus analyzed in a Colombian parasite population. By contrast with P. falciparum msp-7 loci and ancestral P. vivax msp-7 genes, specie-specific duplicates of the latter specie display high genetic variability, generated by single nucleotide polymorphisms, repeat regions, and recombination. At least three major allele types are present in Pvmsp-7C, Pvmsp-7H and Pvmsp-7I and positive selection seems to be operating on the central region of these msp-7 genes. Although this region has high genetic polymorphism, the C-terminus (Pfam domain ID: PF12948) is conserved and could be an important candidate when designing a subunit-based antimalarial vaccine.

Genetic diversity and selection in three plasmodium vivax merozoite surface protein 7 (pvmsp-7) genes in a colombian population

A completely effective vaccine for malaria (one of the major infectious diseases worldwide) is not yet available; different membrane proteins involved in parasite-host interactions have been proposed as candidates for designing it. It has been found that proteins encoded by the merozoite surface protein (msp)-7 multigene family are antibody targets in natural infection; the nucleotide diversity of three Pvmsp-7 genes was thus analyzed in a Colombian parasite population. By contrast with P. falciparum msp-7 loci and ancestral P. vivax msp-7 genes, specie-specific duplicates of the latter specie display high genetic variability, generated by single nucleotide polymorphisms, repeat regions, and recombination. At least three major allele types are present in Pvmsp-7C, Pvmsp-7H and Pvmsp-7I and positive selection seems to be operating on the central region of these msp-7 genes. Although this region has high genetic polymorphism, the C-terminus (Pfam domain ID: PF12948) is conserved and could be an important candidate when designing a subunit-based antimalarial vaccine.

Equilibrium Principle in Colombian Public Contracting

Public contracting in Colombia is conflicting and inefficient. It frequently leads to damage to State property. The Colombian legal system cannot assure efficient and transparent public contracting. The cause is the institutional environment characterized by high transaction costs. Colombian law worsens the process by recognizing the principle of economic equilibrium in public contracts. This principle increasese contract incompleteness and renders impossible the use of economic incentives to control the opportunism of the economic agents. The authors present the hypothesis that the economic equilibrium principle increases the conflictive nature of public contracting. They test the hypothesis empirically. The first section of the paper presents a summary of the literature on transaction costs economics, as well as the legal literature on the historical origin and the content of the economic equilibrium principle. The second section describes the methodology of the empirical study. The third section shows the empirical evidence of the effects that the economic equilibrium principle exerts over the public contracting. The last section presents the conclusions.

Preliminary population study of Methylenetetrahydrofolate Reductase (MTHFR) C677T polymorphism determination in a pilot group of students from the University of Rosario

 Introduction: the 5, 10-methylenetetrahydrofolate reductase (MTHFR) is an essential enzyme in folate metabolism; their polymorphisms have been associated with heart disease risk increase, obstetric problems, neural tube defects in fetuses and cancer susceptibility. This gene has a single nucleotide polymorphism, a C-T change at nucleotide 677, which affects significantly its enzymatic activity. Objective: because of the biological importance of this enzyme and the Colombian population genetic heterogeneity characteristic, a study was performed to determine allele and genotype frequencies of MTHFR C677T polymorphism in healthy individuals, taking into account that in Colombia there are only studies that have involved case-control methodology. Methods: we analyzed this polymorphism trough the amplification of the DNA of a 206 students sample population. Additionally, Colombian overall frequencies were calculated, using data from healthy controls reported in other studies. Results: a Hardy-Weinberg disequilibri m was found in the sample tested. For the Colombian data, we found that the global population was in equilibrium. Conclusion: T allele population frequency seems to be under positive selection pressure, which is reflected in the population allele increase, despite its deleterious effect. A Spanish study reported similar results and identified folic acid supplementation on expectant mothers as a probably cause of this change.