El origen histórico del contrato de juego

La concepción jurídica del contrato de juego en la antigua Roma viene marcada por su prohibición legal. La articulación de las acciones romanas basadas en pretensiones jurídicas tutelables impedía desplazamientos patrimoniales fundados en el juego.The legal conception of gambling contracts in ancient Rome is marked by its legal prohibition. The articulations of the roman actions based in legal tutelage presumptions prevented patrimonial displacements based on the game

Linear diffusion with singular absorption potential and/or unbounded convective flow: the weighted space approach

In this paper we prove the existence and uniqueness of very weak solutions to linear diffusion equations involving a singular absorption potential and/or an unbounded convective flow on a bounded open set of $\mathbb R^N$. In most of the paper we consider homogeneous Dirichlet boundary conditions but we prove that when the potential function grows faster than the distance to the boundary to the power -2 then no boundary condition is required to get the uniqueness of very weak solutions. This result is new in the literature and must be distinguished from other previous results in which such uniqueness of solutions without any boundary condition was proved for degenerate diffusion operators (which is not our case). Our approach, based on the treatment on some distance to the boundary weighted spaces, uses a suitable regularity of the solution of the associated dual problem which is here established. We also consider the delicate question of the differentiability of the very weak solution and prove that some suitable additional hypothesis on the data is required since otherwise the gradient of the solution may not be integrable on the domain

La participación de los stakeholders de las asociaciones contra el cáncer en Facebook

Esta investigación analiza la estrategia en Facebook de cuatro asociaciones iberoamericanas de lucha contra el cáncer de países donde esta enfermedad representa la segunda causa de mortalidad. El estudio aborda las características que presentan los mensajes que consiguen mayor interacción con el público a través de la opción “comentar”. Las publicaciones más comentadas son aquellas que abordan el cáncer de forma genérica o bien no lo mencionan; además de informar y concienciar persiguen otros objetivos diferentes a los de las asociaciones y emplean la imagen como recurso principal acompañada de un hashtag o enlace a la web de la entidad

Preservation of some stochastic orders by distortion functions with application to coherent systems with exchangeable components

The preservation of stochastic orders by distortion functions has become a topic of increasing interest in the reliability analysis of coherent systems. The reason of this interest is that the reliability function of a coherent system with identically distributed components can be represented as a distortion function of the common reliability function of the components. In this framework, we study the preservation of the excess wealth order, the total time on test transform order, the decreasing mean residual live order and the quantile mean inactivity time order by distortion functions. The results are applied to study the preservation of these stochastic orders under the formation of coherent systems with exchangeable components

Repetitive Movements in Melon Cultivation Workers under Greenhouses

Musculoskeletal disorders cause serious problems that affect workers in many sectors. The objective of this study is the ergonomic analysis of melon cultivation farmers in Almeria-type greenhouses. For this, the rapid upper limb assessment (RULA) method has been applied after carrying out a detailed process of observing the farmers’ tasks. The study shows that 65% of the postures have a very-high-risk level, 26% high, 9% average, and no posture is found with a low risk. They also show that in 69.57% of the postures, the upper limbs are less affected than the others such as the neck, trunk, and lower limbs. Measures are proposed to improve the working conditions for workers

Failure of the Hopf-Oleinik lemma for a linear elliptic problem with singular convection of non-negative divergence

In this paper we study existence, uniqueness, and integrability of solutions to the Dirichlet problem $-\mathrm{div}( M(x) \nabla u ) = -\mathrm{div} (E(x) u) + f$ in a bounded domain of $\mathbb R^N$ with $N \ge 3$. We are particularly interested in singular $E$ with $\mathrm{div} E \ge 0$. We start by recalling known existence results when $|E| \in L^N$ that do not rely on the sign of $\mathrm{div} E$. Then, under the assumption that $\mathrm{div} E \ge 0$ distributionally, we extend the existence theory to $|E| \in L^2$. For the uniqueness, we prove a comparison principle in this setting. Lastly, we discuss the particular cases of $E$ singular at one point as $Ax /|x|^2$, or towards the boundary as $\mathrm{div} E \sim \mathrm{dist}(x, \partial \Omega)^{-2-\alpha}$. In these cases the singularity of $E$ leads to $u$ vanishing to a certain order. In particular, this shows that the Hopf-Oleinik lemma, i.e. $\partial u / \partial n < 0$, fails in the presence of such singular drift terms $E$