Carlos Carleos

Genetic diversity measures of local European beef cattle breeds for conservation purposes

This study was undertaken to determine the genetic structure, evolutionary relationships, and the genetic diversity among 18 local cattle breeds from Spain, Portugal, and France using 16 microsatellites. Heterozygosities, estimates of Fst, genetic distances, multivariate and diversity analyses, and assignment tests were performed. Heterozygosities ranged from 0.54 in the Pirenaica breed to 0.72 in the Barrosã breed. Seven percent of the total genetic variability can be attributed to differences among breeds (mean Fst = 0.07; P < 0.01). Five different genetic distances were computed and compared with no correlation found to be significantly different from 0 between distances based on the effective size of the population and those which use the size of the alleles. The Weitzman recursive approach and a multivariate analysis were used to measure the contribution of the breeds diversity. The Weitzman approach suggests that the most important breeds to be preserved are those grouped into two clusters: the cluster formed by the Mirandesa and Alistana breeds and that of the Sayaguesa and Tudanca breeds. The hypothetical extinction of one of those clusters represents a 17% loss of diversity. A correspondence analysis not only distinguished four breed groups but also confirmed results of previous studies classifying the important breeds contributing to diversity. In addition, the variation between breeds was sufficiently high so as to allow individuals to be assigned to their breed of origin with a probability of 99% for simulated samples.

Heterozygosity-fitness correlations in the gilthead sea bream Sparus aurata using microsatellite loci from unknown and gene-rich genomic locations

Heterozygosity-fitness correlations (HFC) were assessed for a sample of a gilthead sea bream Sparus aurata population. Two hundred and seventy-one fish were genotyped at 22 known and novel microsatellite loci, from which correlations between the multilocus heterozygosity index (I(MLH) ) and various fitness traits (fork length, mass and specific growth rates) were calculated. Significant global HFCs were found in this sample (0·02 ≤r(2) ≤ 0·08). In addition, all the significant correlations found in this work were negative, indicating that heterozygotes had lower fitness than their homozygote counterparts. Marker location could not explain the observed HFCs. Evidence of inbreeding, outbreeding or population and family structuring was not found in this work. The presence of undetected general effects that may lead to the appearance of HFCs, however, cannot be ruled out. These results seem to be best explained by the occurrence of local effects (due to linkage) or even by possible direct locus advantages.

Powerful nonparametric statistics to compare k independent ROC curves

The authors deal with the problem of comparing receiver operating characteristic (ROC) curves from independent samples. From a nonparametric approach, they propose and study three different statistics. Their asymptotic distributions are obtained and a resample plan is considered. In order to study the statistical power of the introduced statistics, a simulation study is carried out. The (observed) results suggest that, for the considered models, the new statistics are more powerful than the usually employed ones (the Venkatraman test and the usual area under the ROC curve criterion) in non-uniform dominance situations and quite good otherwise.

Power analysis of QTL detection in half-sib families using selective DNA pooling

Individual loci of economic importance (QTL) can be detected by comparing the inheritance of a trait and the inheritance of loci with alleles readily identifiable by laboratory methods (genetic markers). Data on allele segregation at the individual level are costly and alternatives have been proposed that make use of allele frequencies among progeny, rather than individual genotypes. Among the factors that may affect the power of the set up, the most important are those intrinsic to the QTL: the additive effect of the QTL, and its dominance, and distance between markers and QTL. Other factors are relative to the choice of animals and markers, such as the frequency of the QTL and marker alleles among dams and sires. Data collection may affect the detection power through the size of half-sib families, selection rate within families, and the technical error incurred when estimating genetic frequencies. We present results for a sensitivity analysis for QTL detection using pools of DNA from selected half-sibs. Simulations showed that conclusive detection may be achieved with families of at least 500 half-sibs if sires are chosen on the criteria that most of their marker alleles are either both missing, or one is fixed, among dams.

An indexed dispersion criterion for testing the sex-biased dispersal of lek mating behavior of capercaillies

Traditionally it has been assumed by ecologists that the dispersion of positions with respect to leks of female capercaillies during the mating season is superior to the dispersion of positions of male capercaillies. However some recently published articles suggest the idea that dispersion is not sex-biased, but both sexes show a similar dispersion. This article introduces a mathematical model to approach the study of the above question by means of an indexed dispersion criterion. This model is developed in detail thus deriving its main mathematical properties. On this basis, the model is applied to the analysis of the motivating problem with real data of positions of leks and female and male capercaillies. The results derived by means of the model put into doubt the traditional assumption of a superior dispersion of females supporting the new theories, that is, both sexes show a similar dispersion.

Optimization of a membrane hybrid process for oil-in-water emulsions treatment using Taguchi experimental design

AbstractA coagulation–centrifugation/ultrafiltration hybrid process has been performed for the treatment of a commercial oil-in-water emulsion used in metalworking operations. The effect of pre-treatment stage on membrane fouling was evaluated to ascertain the main fouling mechanism and to establish the best membrane cleaning procedure. The hybrid process was optimized in terms of the maximum ultrafiltration (UF) permeate flux. Destabilization temperature, transmembrane pressure, feed flow rate to the UF module, and coagulant salt molar concentration were selected as factors. The experiments were designed using Taguchi method, and the contribution of each factor was determined using a statistical analysis of variance. Experimental results were also discussed in terms of environmental parameters (chemical oxygen demand [COD], conductivity, pH, and turbidity) for the main process streams. The best fit to experimental data of permeate flux decline corresponded to the cake/gel layer formation model. The clean...

Ranking Star-Shaped Valued Mappings with Respect to Shape Variability

The study of shapes is a difficult topic, but it is becoming more and more important as computer vision techniques are already crucial in many research fields. Concretely, the variability of shapes is the basis for many criteria of symptom definition in medical diagnosis. This article introduces a stochastic order to address the variability of star-shaped sets. The main properties of the order are analyzed. An example of an application to hypothesis testing in medical diagnosis is also provided. Namely, we study if there are significant differences between healthy and diseased corneal endothelia with respect to cell shapes by means of ocular images.

Hypothesis testing-based comparative analysis between rating scales for intrinsically imprecise data

Abstract In previous papers, it has been empirically proved that descriptive (summary measures) and inferential conclusions (in particular, tests about means p -values) with imprecise-valued data are often affected by the scale considered to model such data. More concretely, conclusions from the numerical and fuzzy linguistic encodings of Likert-type data have been compared with those for fuzzy data obtained by using a totally free fuzzy assessment: the so-called fuzzy rating scale. These previous comparisons have been performed separately for each of the scales. This paper aims to perform a joint comparison in such a way that means of linked data (one associated with the fuzzy rating and the other one with the encoded Likert scale) are to be tested for equality. Two real-life examples, as well as several simulation-based synthetic ones, have unequivocally shown that the fuzzy rating scale means are significantly different from those for the encoded Likert scales.

A Stochastic Order of Shape Variability with an Application to Cell Nuclei Involved in Mastitis

Variability of shapes of bidimensional closed curves is a key matter in many fields of research. A statistical order of bidimensional shape variability is introduced in this paper. For such a purpose a special class of random elements is considered. The order is defined on such a class and the main properties of the order are analyzed. Such an order involves the curvature of a special parameterization of bidimensional closed curves. The new order can be used as a basis for implementing statistical procedures, such as hypothesis testing on variability of shapes. An example is developed by means of the image analysis of cell nuclei, namely the shapes of cell nuclei in mastitis-affected cow milk and non-affected cow milk are compared.

A Case Study-Based Analysis of the Influence of the Fuzzy Data Shape in Quantifying Their Fréchet’s Variance

In previous studies it has been shown that assumming a trapezoidal shape to model fuzzy number-valued data is not statistically restrictive in case we focus on the (Aumann-type) means of these data. The assertion has been supported by both case and simulation studies. This paper aims to analyze by means of a case study whether the same assertion applies in dealing with the Frechet-type variance. More concretely, the p-values of tests have been compared for trapezoidal assessment versus other frequently used ones, like some LR assessments. The analysis is illustrated and corroborated with a real-life example. This analysis indicates that the shape of the fuzzy assessment scarcely affects statistical conclusions.