On eulerian equilibria in K-order approximation of the gyrostat in the three-body

We consider the noncanonical Hamiltonian dynamics of a gyrostat in the three-body problem. By means of geometric-mechanics methods we study the approximate Poisson dynamics that arises when we develop the potential in series of Legendre and truncate this in an arbitrary order k. Working in the reduced problem, the existence and number of equilibria, that we denominate of Euler type in analogy with classic results on the topic,are considered. Necessary and sufficient conditions for their existence in an approximate dynamics of order k are obtained and we give explicit expressions of these equilibria, useful for the later study of the stability of the same ones. A complete study of the number of Eulerian equilibria is made in approximate dynamics of orders zero and one. We obtain the main result of this work, the number of Eulerian equilibria in an approximate dynamics of order k for k ≥ 1 is independent of the order of truncation of the potential if the gyrostat S0 is close to the sphere. The instability of Eulerian equilibria is proven for any approximate dynamics if the gyrostat is close to the sphere. In this way, we generalize the classical results on equilibria of the three-body problem and many of those obtained by other authors using more classic techniques for the case of rigid bodies.The authors are grateful to the referee for his useful suggestions and comments which improved the paper. This research was partially supported by the Spanish Ministerio de Ciencia y Tecnologìa (Project BFM2003-02137) and by the Consejerìa de Educaciòn y Cultura de la Comunidad Autónoma de la Región de Murcia (Project S´eneca 2002: PCMC/ 3/00074/FS/02)

Planar rotations for a gyrostat in the three-body problem

We consider the non-canonical Hamiltonian dynamics of a gyrostat in the three body problem. By means of geometric-mechanics methods we study the approximate Poisson dynamics that arises when we develop the potential in series of Legendre and truncate this in an arbitrary order k. Working in the reduced problem,the existence and number of equilibria, that we denominate planar rotation type in analogy with classic results on the topic, is considered. Necessary and sufficient conditions for their existence in a approximate dynamics of order k is obtained and we give explicit expressions of this equilibria, useful for the later study of the stability of the same ones. A complete study of the planar rotation type equilibria is made in approximate dynamics or order zero and one.This research was partially supported by the Spanish Ministerio de Ciencia y Tecnología (Project BFM2003-02137) and by the Consejería de Educación y Cultura de la Comunidad Autónoma de la Región de Murcia (Project Séneca 2002: PC-MC/3/00074/FS/02)

Profile-based latent class distance association analyses for sparse tables:application to the attitude of European citizens towards sustainable tourism

Social and behavioural sciences often deal with the analysis of associations for cross-classified data. This paper focuses on the study of the patterns observed on European citizens regarding their attitude towards sustainable tourism, specifically their willingness to change travel and tourism habits to be more sustainable. The data collected the intention to comply with nine sustainable actions; answers to these questions generated individual profiles; moreover, European country belonging is reported. Therefore, unlike a variable-oriented approach, here we are interested in a person-oriented approach through profiles. Some traditional methods are limited in their performance when using profiles, for example, by sparseness of the contingency table. We removed many of these limitations by using a latent class distance association model, clustering the row profiles into classes and representing these together with the categories of the response variable in a low-dimensional space. We showed, furthermore, that an easy interpretation of associations between clusters’ centres and categories of a response variable can be incorporated in this framework in an intuitive way using unfolding. Results of the analyses outlined that citizens mostly committed to an environmentally friendly behavior live in Sweden and Romania; citizens less willing to change their habits towards a more sustainable behavior live in Belgium, Cyprus, France, Lithuania and the Netherlands. Citizens preparedness to change habits however depends also on their socio-demographic characteristics such as gender, age, occupation, type of community where living, household size, and the frequency of travelling before the Covid-19 pandemic.Universidad de Granada/CBU

Distribuciones discretas en MDS para datos de disimilaridad generados mediante cuestionarios

En este trabajo se propone la utilización de distribuciones estadísticas discretas como alternativa a la distribución lognormal para la modelización de datos de disimilaridad provenientes de escalas con pocas modalidades en los modelos confirmatorios MDS de Ramsay y Vera. Los resultados ponen de manifiesto que las distribuciones más apropiadas son las mixturas Poisson-lognormal y Poisson-gaussiana inversa. El análisis de datos simulados confirma la falta de adecuación de un modelo continuo a datos provenientes de las escalas generalmente utilizadas en los procedimientos de sondeo de opinión subjetiva de comparación de pares.We propose here the use of discrete statistical distributions for analysing dissimilarity data deriving from scales containing few categories as an alternative to the lognormal distribution used in Ramsay and Vera's MDS probabilistic models. Our results show that the most suitable distributions are Poisson-lognormal and Poisson-inverseGaussian mixtures. An analysis of simulated data confirms the inadequacy of a continuous model for analysing the data within the scales generally used in opinion polls requiring the subjective comparison of pairs of answers

PEPPER, a novel K-homology domain gene, regulates vegetative and gynoecium development in Arabidopsis

AbstractPistil final morphology relies on floral meristem homeostasis, proper organ specification and regional differentiation. These are developmental processes in which sophisticated signaling networks are being uncovered. However, further elements for fine-tuning adjustment still remain to be disclosed. At the molecular level, posttranscriptional modulators may fit such a profile. In this work, we describe the characterization of PEPPER (PEP), a novel Arabidopsis gene encoding a polypeptide with K-homology (KH) RNA-binding modules, which acts on vegetative growth and pistil development. PEP was initially identified as one of the gene functions affected in a complex mutant carrying a chromosomal reorganization, which exhibits aberrant phyllotaxy and small fruits with supernumerary carpels. In contrast, plants carrying single-gene pep null mutations exhibit subtle morphological alterations. Individuals bearing a stronger-than-null allele present a phenotype comprising leaf alterations, phyllotactic errors and sporadic presence of fruits with multiple valves. Accordingly, dynamic PEP expression was detected in all major organs examined. Complementation experiments with a PEP genomic clone confirmed a role for PEP as a regulator in vegetative and reproductive development. Moreover, our genetic studies suggest that PEP interacts with element(s) of the CLAVATA signaling pathway

CONCENTRACIÓN ACCIONARIAL Y LIQUIDEZ DE MERCADO: UN ANALISIS CON ECUACIONES SIMULTÁNEAS

This paper analyzes the relationship between ownership concentration andshares liquidity for a sample of 115 listed firms that traded during the period from April2000 to December 2000. Results show a negative influence of ownership of directors,major shareholders and outside shareholders on liquidity. We do not find evidence ofthe influence of liquidity on the ownership concentration. We also observe that theownership concentration increases the adverse selection spread component. Therefore,firms with higher ownership concentration present larger informative asymmetry,having less liquidity. Este trabajo analiza la relación entre la concentración accionarial y la liquidez de las acciones, para una muestra de 115 empresas que cotizaban en el Mercado Continuo en el período de abril a diciembre de 2000. Los resultados obtenidos ponen de manifiesto un efecto negativo del porcentaje de acciones que poseen los consejeros, principales propietarios y accionistas externos en la mencionada liquidez, no hallando evidencia de la relación contraria. Además, observamos que la concentración accionarial incrementa el componente de selección adversa. Por tanto, las empresas más concentradas presentan mayor asimetría informativa, detectándose en ellas una menor liquidez.Concentración accionarial, liquidez, microestructura ownership structure, liquidity, microstructure

d-Pinitol promotes tau dephosphorylation through a cyclin-dependent kinase 5 regulation mechanism: A new potential approach for tauopathies?

Background and Purpose Recent evidence links brain insulin resistance with neurodegenerative diseases, where hyperphosphorylated tau protein contributes to neuronal cell death. In the present study, we aimed to evaluate if d-pinitol inositol, which acts as an insulin sensitizer, affects the phosphorylation status of tau protein. Experimental Approach We studied the pharmacological effect of d-pinitol on insulin signalling and tau phosphorylation in the hippocampus of Wistar and Zucker rats. To this end, we evaluated by western blotting the Akt pathway and its downstream proteins as being one of the main insulin-mediator pathways. Also, we explored the functional status of additional kinases phosphorylating tau, including PKA, ERK1/2, AMPK and CDK5. We utilized the 3xTg mouse model as a control for tauopathy, since it carries tau mutations that promote phosphorylation and aggregation. Key Results Surprisingly, we discovered that oral d-pinitol treatment lowered tau phosphorylation significantly, but not through the expected kinase GSK-3 regulation. An extensive search for additional kinases phosphorylating tau revealed that this effect was mediated through a mechanism dependent on the reduction of the activity of the CDK5, affecting both its p35 and p25 subunits. This effect disappeared in leptin-deficient Zucker rats, uncovering that the association of leptin deficiency, obesity, dyslipidaemia and hyperinsulinaemia abrogates d-pinitol actions on tau phosphorylation. The 3xTg mice confirmed d-pinitol effectiveness in a genetic AD-tauopathy.Medina-Vera, D., Navarro, J. A., Rivera, P., Rosell-Valle, C., Gutiérrez-Adán, A., Sanjuan, C., López-Gambero, A. J., Tovar, R., Suárez, J., Pavón, F. J., Baixeras, E., Decara, J., & Rodríguez de Fonseca, F. (2022). d-Pinitol promotes tau dephosphorylation through a cyclin-dependent kinase 5 regulation mechanism: A new potential approach for tauopathies? British Journal of Pharmacology, 179( 19), 4655– 4672. https://doi.org/10.1111/bph.1590

La gestión de los recursos humanos en las organizaciones sindicales

El capital humano o los recursos humanos de una organización sindical lo conforman tanto los miembros de los órganos de representación unitarios como los miembros de los órganos de representación sindical. Todos ellos amparados en una legislación básica de derechos fundamentales, y en una estructurada y firme organización interna, donde el denominador común será la voluntariedad del ejercicio de sus acciones en el centro de trabajo y, de forma interna, en los órganos del sindicato. Será en este criterio, la voluntariedad, donde radique la peculiaridad en la gestión de este personal, pues su motivación ha de ser distinta a la de un asalariado o con una relación contractual económica. En concreto, la premisa que está constantemente en la mente de los gestores de estos recursos humanos es sencilla y simple: «si yo no te pago ni te compenso y/o gratifico con vacaciones ni promoción profesional, cómo te ordeno, motivo y coordino, llevándote a situaciones de tensión límites derivadas de un exceso de horas, trabajo, dedicación y responsabilidad, todo ello amparándome en unas siglas respetadas y/o amadas teóricamente por todos». El secreto radica en una serie de factores que conforman una columna vertebral sobre la que asentar la organización y gestión como asumir un nuevo modelo de organización; una dirección participativa; una selección de candidatos a través de la elaboración clara de un catálogo de puestos de trabajo con sus perfiles profesionales, funciones y evaluación; una implicación del equipo; una crítica constructiva; adecuada motivación; participación; esfuerzo; etc

Soluciones de equilibrio en un problema generalizado del de Lagrange-Poisson: condiciones necesarias y suficientes de estabilidad

In this paper, we consider the problem of motion of a symmetrical gyrostat with a fixed point in a Newtonian force field, where the potential function adopts the form U = U(K3), the gyrostatic momentum and the position vector of the center of mass are on the axis of symmetry. First, we obtain the equilibrium positions of this problem; then, by means of the Energy-Casimir method, we give sufficient conditions of stability for some of these equilibria and, by spectral methods, we obtain necessary conditions of stability. The obtained results generalize the previous papers [7], [8],[9], [1] and [2].MECD (Proyecto no PB98-1576)