Los medios de comunicación y el tatuaje contemporáneo

El fenómeno del tatuaje, inicialmente asociado a grupos étnicos tradicionales y más tarde a culturas marginales,ha tenido en las últimas décadas una expresión inédita en las sociedades contemporáneas extendiéndose entre sectores poblacionales muy diversos, antaño ajenos a esta práctica. Originariamente asociado a lo ritual y lo sagrado, ha devenido para algunos en elemento de moda impulsado por los canales de difusión mediada. Su presencia es evidente en las calles pero también en los medios de comunicación. En este artículo se aborda el papel de los medios de comunicación en este estado de cosas. En esta investigación se han realizado entrevistas en profundidad tanto a profesionales del tatuaje como a personas tatuadas para conocer los diversos aspectos implicados en la mediatización del tatuaje y en su ejecución. Como resultado de las entrevistas se ha podido constatar que los medios han incidido en la extensión de esta práctica, tanto desde la perspectiva evidente de su presencia cuantitativa en entornos urbanos cuanto desde los diferentes modos en los que la visibilidad que los media otorgan al tatuaje a través de diversas plataformas y formatos interviene en múltiples ámbitos que abarcan desde la formación de los tatuadores, los estilos visuales, la legitimación social de su uso, el significado personal que se da a los tatuajes y la modulación del relato en torno al hecho de tatuarse, entre otros

Three-Body Dynamics and Self-Powering of an Electrodynamic Tether in a Plasmasphere

The dynamics of an electrodynamic tether in a three-body gravitational environment are investigated. In the classical two-body scenario the extraction of power is at the expense of orbital kinetic energy. As a result of power extraction, an electrodynamic tether satellite system loses altitude and deorbits. This concept has been proposed and well investigated in the past, for example for orbital debris mitigation and spent stages reentry. On the other hand, in the three-body scenario an electrodynamic tether can be placed in an equilibrium position fixed with respect to the two primary bodies without deorbiting, and at the same time generate power for onboard use. The appearance of new equilibrium positions in the perturbed three-body problem allow this to happen as the electrical power is extracted at the expenses of the plasma corotating with the primary body. Fundamental differences between the classical twobody dynamics and the new phenomena appearing in the circular restricted three-body problem perturbed by the electrodynamic force of the electrodynamic tether are shown in the paper. An interesting application of an electrodynamic tether placed in the Jupiter plasma torus is then considered, in which the electrodynamic tether generates useful electrical power of about 1 kW with a 20-km-long electrodynamic tether from the environmental plasma without losing orbital energy

Energy Analysis of Bare Electrodynamic Tethers

The design of an electrodynamic tether is a complex task that involves the control of dynamic instabilities, optimization of the generated power (or the descent time in deorbiting missions), and minimization of the tether mass. The electrodynamic forces on an electrodynamic tether are responsible for variations in the mechanical energy of the tethered system and can also drive the system to dynamic instability. Energy sources and sinks in this system include the following: 1) ionospheric impedance, 2) the potential drop at the cathodic contactor, 3) ohmic losses in the tether, 4) the corotational plasma electric field, and 5) generated power and/or 6) input power. The analysis of each of these energy components, or bricks, establishes parameters that are useful tools for tether design. In this study, the nondimensional parameters that govern the orbital energy variation, dynamic instability, and power generation were characterized, and their mutual interdependence was established. A space-debris mitigation mission was taken as an example of this approach for the assessment of tether performance. Numerical simulations using a dumbbell model for tether dynamics, the International Geomagnetic Reference Field for the geomagnetic field, and the International Reference Ionosphere for the ionosphere were performed to test the analytical approach. The results obtained herein stress the close relationships that exist among the velocity of descent, dynamic stability, and generated power. An optimal tether design requires a detailed tradeoff among these performances in a real-world scenario

Perigosidade radiológica na cidade do presente: a contribuição dos materiais de construção para a dose externa resultante da radiação gama

A radioatividade associada com os materiais de construção (pela presença de átomos radioativos) é um dos potenciais riscos que podem afetar as pessoas que ocupam espaços construídos com esses materiais, quer pela via da inalação quer pela via da dose externa associada com a radiação gama. Nesta comunicação pretendemos fazer uma revisão de informações existentes sobre a contribuição de materiais de construção para a dose externa resultante da radiação gama, considerando sobretudo os materiais geológicos (mas as considerações apresentadas estendem-se aos materiais de construção em geral), nomeadamente no contexto das caraterísticas da cidade do presente. É na cidade do presente que vamos ter uma maior diversidade de estruturas, que vão ter uma perigosidade radiológica variável em função dos materiais utilizados e da tipologia de construção. A diversidade dos materiais encontrados pode ir muito além dos limites regionais e podem existir materiais com níveis muito superiores aos dos materiais locais, em proporções e geometrias muito diversas. O processo de envelhecimento das populações na cidade do presente pode, também, implicar maiores tempos de permanência em espaços interiores, aumentando a dose associada com a radiação gama externa.Este trabalho foi desenvolvido no âmbito das atividades do Lab2PT- Laboratório de Paisagens, Património e Território (AUR/04509) financiado pela FCT através de fundos nacionais e quando aplicável do cofinanciamento do FEDER, no âmbito dos novos acordos de parceria PT2020 e COMPETE 2020 – POCI-01-0145-FEDER-007528. O grupo de investigação CULXEO de que faz parte J. Sanjurjo-Sánchez é financiado pela Xunta de Galicia através do programa “Consolidación e estructuración de unidades de investigación competitivas — Grupo de potencial de crecimiento” (GPC2015/024)

Regulation of Angiogenesis Discriminates Tissue Resident MSCs from Effective and Defective Osteogenic Environments

[Abstract] Background: The biological mechanisms that contribute to atrophic long bone non-union are poorly understood. Multipotential mesenchymal stromal cells (MSCs) are key contributors to bone formation and are recognised as important mediators of blood vessel formation. This study examines the role of MSCs in tissue formation at the site of atrophic non-union. Materials and Methods: Tissue and MSCs from non-union sites (n = 20) and induced periosteal (IP) membrane formed following the Masquelet bone reconstruction technique (n = 15) or bone marrow (n = 8) were compared. MSC content, differentiation, and influence on angiogenesis were measured in vitro. Cell content and vasculature measurements were performed by flow cytometry and histology, and gene expression was measured by quantitative polymerase chain reaction (qPCR). Results: MSCs from non-union sites had comparable differentiation potential to bone marrow MSCs. Compared with induced periosteum, non-union tissue contained similar proportion of colony-forming cells, but a greater proportion of pericytes (p = 0.036), and endothelial cells (p = 0.016) and blood vessels were more numerous (p = 0.001) with smaller luminal diameter (p = 0.046). MSCs showed marked differences in angiogenic transcripts depending on the source, and those from induced periosteum, but not non-union tissue, inhibited early stages of in vitro angiogenesis. Conclusions: In vitro, non-union site derived MSCs have no impairment of differentiation capacity, but they differ from IP-derived MSCs in mediating angiogenesis. Local MSCs may thus be strongly implicated in the formation of the immature vascular network at the non-union site. Attention should be given to their angiogenic support profile when selecting MSCs for regenerative therapy

Dependence On Volume Of The Phonon Frequencies And The Ir Effective Charges Of Several Iii-v Semiconductors

The mode Grüneisen parameters of the LO and TO Raman phonons of AlN, BN, and BP, and the dependence of eT* on lattice constant have been measured by Raman scattering in a diamond anvil cell. The results for eT* are interpreted by means of pseudopotential calculations of eT* versus lattice constant. © 1983 The American Physical Society.2884579458