Bayesian inference for the multivariate skew-normal model: a Population Monte Carlo approach

Frequentist and likelihood methods of inference based on the multivariate skew-normal model encounter several technical difficulties with this model. In spite of the popularity of this class of densities, there are no broadly satisfactory solutions for estimation and testing problems. A general population Monte Carlo algorithm is proposed which: 1) exploits the latent structure stochastic representation of skew-normal random variables to provide a full Bayesian analysis of the model and 2) accounts for the presence of constraints in the parameter space. The proposed approach can be defined as weakly informative, since the prior distribution approximates the actual reference prior for the shape parameter vector. Results are compared with the existing classical solutions and the practical implementation of the algorithm is illustrated via a simulation study and a real data example. A generalization to the matrix variate regression model with skew-normal error is also presented

Objective Bayesian analysis for the multivariate skew-t model

We perform a Bayesian analysis of the p-variate skew-t model, providing a new parameterization, a set of non-informative priors and a sampler specifically designed to explore the posterior density of the model parameters. Extensions, such as the multivariate regression model with skewed errors and the stochastic frontiers model, are easily accommodated. A novelty introduced in the paper is given by the extension of the bivariate skew-normal model given in Liseo & Parisi (2013) to a more realistic p-variate skew-t model. We also introduce the R package mvst, which allows to estimate the multivariate skew-t model

Politicians “on board”! Do political connections affect banking activities in Italy?

This paper analyzes the effects of political presence in the boards of directors of cooperative banks. We refer our analysis to all politicians (almost 160.000) belonging to a political body in Italy. Overall, our dataset contains 1.858 board members referring to 127 cooperative banks. Results show that politically connected banks, in which politicians have executive roles in the board of directors, display higher net interest revenues, lower quality of the loans portfolio and lower efficiency relative to a control group of non-connected counterparts. Therefore, in the current debate on the reform of the statutes of the Italian cooperative banks, we argue that the problem is not for politicians to be in the boards but for them to hold executive positions.Cooperative Banks, Politics, Corporate Governance

Biological compatibility between two temperate lineages of brown dog ticks, Rhipicephalus sanguineus (sensu lato)

Background: The brown dog tick Rhipicephalus sanguineus (sensu stricto) is reputed to be the most widespread tick of domestic dogs worldwide and has also been implicated in the transmission of many pathogens to dogs and humans. For more than two centuries, Rh. sanguineus (s.s.) was regarded as a single taxon, even considering its poor original description and the inexistence of a type specimen. However, genetic and crossbreeding experiments have indicated the existence of at least two distinct taxa within this name: the so-called "temperate" and "tropical" lineages of Rh. sanguineus (sensu lato). Recent genetic studies have also demonstrated the existence of additional lineages of Rh. sanguineus (s.l.) in Europe and Asia. Herein, we assessed the biological compatibility between two lineages of Rh. sanguineus (s.l.) found in southern Europe, namely Rhipicephalus sp. I (from Italy) and Rhipicephalus sp. II (from Portugal). Methods: Ticks morphologically identified as Rh. sanguineus (s.l.) were collected in southern Portugal and southern Italy. Tick colonies were established and crossbreeding experiments conducted. Morphological, biological and genetic analyses were conducted. Results: Crossbreeding experiments confirmed that ticks from the two studied lineages were able to mate and generate fertile hybrids. Hybrid adult ticks always presented the same genotype of the mother, confirming maternal inheritance of mtDNA. However, larvae and nymphs originated from Rhipicephalus sp. I females presented mtDNA genotype of either Rhipicephalus sp. I or Rhipicephalus sp. II, suggesting the occurrence of paternal inheritance or mitochondrial heteroplasmy. While biologically compatible, these lineages are distinct genetically and phenotypically. Conclusions: The temperate lineages of Rh. sanguineus (s.l.) studied herein are biologically compatible and genetic data obtained from both pure and hybrid lines indicate the occurrence of paternal inheritance or mitochondrial heteroplasmy. This study opens new research avenues and raises question regarding the usefulness of genetic data and crossbreeding experiments as criteria for the definition of cryptic species in ticks

Dolphin Morbillivirus in Eurasian Otters, Italy

We report biomolecular evidence of dolphin morbillivirus in 4 wild Eurasian otters (Lutra lutra) from southern Italy; 2 animals showed simultaneous immunohistochemical reactivity against morbilliviral antigen. These cases add further concern and support to the progressively expanding host range of dolphin morbillivirus in the western Mediterranean Sea

Estudios biológicos in vitro de materiales utilizados en osteosíntesis

Contexto: diferentes materiales son utilizados para fabricar prótesis empleadas en medicina reparadora siendo el titanio, por sus características químicas, el más frecuentemente empleado. Propósito: en el presente trabajo se evalúa la biocompatibilidad de diferentes muestras de prótesis médicas fabricadas por la Empresa FICO S.A. Métodos: mediante técnicas de citotoxicidad y genotoxicidad se estudió su potencial capacidad de integrarse a los tejidos, empleándose en los bioensayos cultivos celulares de las líneas UMR-106 y L929. Por medio de las técnicas de rojo neutro, colorimétrico de MTT, contacto directo, difusión en agar y producción de colágeno se estudiaron los niveles de citotoxicidad. Además, a través de la técnica de naranja de acridina se determinó la viabilidad celular. El “ensayo cometa” se empleó para determinar la genotoxicidad. Resultados: los resultados de los bioensayos empleados mostraron una alta biocompatibilidad, y no se evidenciaron diferencias significativas con los controles negativos. Conclusión: las técnicas empleadas en el presente trabajo pueden constituirse en herramientas para el análisis de materiales de uso biomédico.Context: some materials are used to factory medical prosthesis, in repairing medicine. Titanium is the most common used material bi their chemical characteristics. Aim: to evaluate biocompatibility in different samples of medical prosthesis, manufactured by FICO S.A. enterprise.Methods: through cytotoxicity and genotoxicity techniques, it analyzed the potential capability to integrate into the tissues, working with cell cultures and cell lines UMR-106 y L929. Also it used techniques such as, neutro red, colorimetric of MTT, direct contact, diffusion on agar and collagen production, it evaluated the cytotoxicity levels. Also with acridine orange technique it sets cell viability. Comet essay was used to establish genotocicity. Results: the study shows high biocompatibility, and it does not found significant difference in negative controls. Conclusion: It recommends these techniques to evaluate biomedical prosthesis.Fil: Castrogiovanni, Daniel Cayetano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Multidisciplinario de Biología Celular. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Multidisciplinario de Biología Celular. Universidad Nacional de La Plata. Instituto Multidisciplinario de Biología Celular; ArgentinaFil: Parisi, Julieta Marcia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Multidisciplinario de Biología Celular. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Multidisciplinario de Biología Celular. Universidad Nacional de La Plata. Instituto Multidisciplinario de Biología Celular; ArgentinaFil: Reigosa, Miguel Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Multidisciplinario de Biología Celular. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Multidisciplinario de Biología Celular. Universidad Nacional de La Plata. Instituto Multidisciplinario de Biología Celular; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; Argentin

Yellow laser performance of Dy3+^{3+} in co-doped Dy,Tb:LiLuF4_4

We present laser results obtained from a Dy$^{3+}$-Tb$^{3+}$ co-doped LiLuF$_{4}$ crystal, pumped by a blue emitting InGaN laser diode, aiming for the generation of a compact 578 nm source. We exploit the yellow Dy$^{3+}$ transition $^{4}$F$_{9/2}$ $\Longrightarrow$ $^{6}$H$_{13/2}$ to generate yellow laser emission. The lifetime of the lower laser level is quenched via energy transfer to co-doped Tb$^{3+}$ ions in the fluoride crystal. We report the growth technique, spectroscopic study and room temperature continuous wave (cw) laser results in a hemispherical cavity at 574 nm and with a highly reflective output coupler at 578 nm. A yellow laser at 578 nm is very relevant for metrological applications, in particular for pumping of the forbidden $^{1}$S$_{0} \Longrightarrow ^{3}$P$_{0}$ Ytterbium clock transition, which is recommended as a secondary representation of the second in the international system (SI) of units. This paper was published in Optics Letters and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://dx.doi.org/10.1364/OL.39.006628. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.Comment: 8 pages, 5 figure

Density Local Discriminant Bases for the analysis of otolith morphology in fish identification applications

Postprint (published version