A arte atlântica do Crastoeiro (Norte de Portugal) : contextos e significados

Basados en los resultados de las excavaciones arqueológicas realizadas en los complejos I y II del arte atlántico de Crastoeiro, localizados en el Monte de la Senhora da Graça y partiendo del supuesto de que los individuos no sólo viven en un espacio sino que también están inmersos o incorporados en el, este trabajo tiene como objetivo establecer algunas interpretaciones no sólo sobre la biografía de cada uno de estos loci, sino también, entender los diferentes procesos de interacción de las comunidades locales con el Monte da Senhora da Graça, especialmente aquellos que se relacionan con la elección, la construcción, la frecuencia y las acciones inherentes al uso de estos lugares que designamos arte rupestre

Interaction between vortices in models with two order parameters

The interaction energy and force between widely separated strings is analyzed in a field theory having applications to superconducting cosmic strings, the SO(5) model of high-temperature superconductivity, and solitons in nonlinear optics. The field theory has two order parameters, one of which is broken in the vacuum (giving rise to strings), the other of which is unbroken in the vacuum but which could nonetheless be broken in the core of the string. If this does occur, there is an effect on the energetics of widely separated strings. This effect is important if the length scale of this second order parameter is longer than that of the other fields in the problem.Comment: 11 pages, 3 figures. Minor changes in the text. Accepted for publication in Phys. Rev.

Between Heroes or Deities? Iron Age Sacrificial Agencies Depicted in Rock 6 From Monte de Porreiras (Northwest Portugal)

The aim of this work is to publish the rock engravings of Monte das Porreira 6, located in the council of Paredes de Coura, in the Northwest of Portugal. The study was based on photogrammetric surveys and subsequent contrast recurring to geometric distance determination./nIt is a profusely decorated rock with a long diachrony of carving. The initial phase includes Classical Atlantic Art, integrated in the regional Neo-Chalcolithic period. The second phase includes representation of several types of equids, horsemen, and antenna-hilted daggers. Based on parallels for such weapons, it is possible to integrate these motifs between the Late Bronze Age and an Early Iron Age of North-western Iberia./nIt is also possible to observe a change from an abstract grammar, during the first phase, to a figurative grammar, in which we can identify a narrative related to human and animal sacrifices, associated with the use of antenna-hilted daggers. These depictions recall a symbolism reminiscent of Strabo's writings, including bronze objects containing sacrificial scenes. The final phase of engraving indicates new symbolic changes, with valorisation of isolated actions perpetrated by horsemen, carrying throwing weapons, which may be a representation of a deity or hero.El objetivo de este trabajo es publicar los grabados rupestres del Monte das Porreira 6, situado en Paredes de Coura, en el no de Portugal. El estudio se ha basado en un levantamiento fotogramétrico y el posterior contraste con la determinación de la distancia geométrica./nSe trata de una roca profusamente decorada con una larga diacronía de grabados. La fase inicial incluye el arte atlántico clásico, integrado en el Calcolítico Reciente. La segunda fase incluye la representación de équidos, jinetes y puñales con mango de antenas. Basándose en los paralelos de dichas armas, es posible integrar estos motivos entre la Edad de Bronce Final y la Edad de Hierro Inicial./nTambién es posible observar el paso de una gramática abstracta, durante la primera fase, a una gramática figurativa, en la que se puede identificar una narrativa relacionada con los sacrificios humanos y de animales, asociada al uso de puñales con mango de antenas. Estas representaciones evocan un simbolismo que recuerda a los textos de Estrabón y objetos de bronce que contienen escenas de sacrificio. La última fase del grabado indica nuevos cambios simbólicos, con la valorización de acciones aisladas perpetradas por un jinete, portando un arma arrojadiza, que pueden representar a una divinidad o a un héroe

Fluid Dynamics of Relativistic Quantum Dust

The microscopic transport equations for free fields are solved using the Schwinger function. Thus, for general initial conditions, the evolution of the energy-momentum tensor is obtained, incorporating the quantum effects exactly. The result for relativistic fermions differs from classical hydrodynamics, which is illustrated for Landau and Bjorken type initial conditions in this model of exploding primordial matter. Free fermions behave like classical dust concerning hydrodynamic observables. However, quantum effects which are present in the initial state are preserved.Comment: 5 pages; LaTe

Winding Number Correlation Functions and Cosmic String Formation

We develop winding number correlation functions that allow us to assess the role of field fluctuations on vortex formation in an Abelian gauge theory. We compute the behavior of these correlation functions in simple circumstances and show how fluctuations are important in the vicinity of the phase transition. We further show that, in our approximation, the emerging population of long/infinite string is produced by the classical dynamics of the fields alone, being essentially unaffected by field fluctuations.Comment: Latex file, 27 pages. 8 figures, available in compressed form by anonymous ftp from ftp://euclid.tp.ph.ic.ac.uk/papers/94-5_39.fig Latex and postscript versions also available at http://euclid.tp.ph.ic.ac.uk/Papers/index.htm

Changes in Thermotolerance and Hsp70 Expression with Domestication in Drosophila melanogaster

To examine how the duration of laboratory domestication may affect Drosophila stocks used in studies of thermotolerance, we measured expression of the inducible heat-shock protein Hsp70 and survival after heat shock in D. melanogaster strains recently collected from nature and maintained in laboratory culture for up to 50 or more generations. After an initial increase in both Hsp70 expression and thermotolerance immediately after transfer to laboratory medium, both traits remained fairly constant over time and variation among strains persisted through laboratory domestication. Furthermore, variation in heat tolerance and Hsp70 expression did not correlate with the length of time populations evolved in the laboratory. Therefore, while environmental variation likely contributed most to early shifts in strain tolerance and Hsp70 expression, other population parameters, for example genetic drift, inbreeding, and selection likely affected these traits little. As long as populations are maintained with large numbers of individuals, the culture of insects in the laboratory may have little effect on the tolerance of different strains to thermal stress

Density-dependence of functional development in spiking cortical networks grown in vitro

During development, the mammalian brain differentiates into specialized regions with distinct functional abilities. While many factors contribute to functional specialization, we explore the effect of neuronal density on the development of neuronal interactions in vitro. Two types of cortical networks, dense and sparse, with 50,000 and 12,000 total cells respectively, are studied. Activation graphs that represent pairwise neuronal interactions are constructed using a competitive first response model. These graphs reveal that, during development in vitro, dense networks form activation connections earlier than sparse networks. Link entropy analysis of dense net- work activation graphs suggests that the majority of connections between electrodes are reciprocal in nature. Information theoretic measures reveal that early functional information interactions (among 3 cells) are synergetic in both dense and sparse networks. However, during later stages of development, previously synergetic relationships become primarily redundant in dense, but not in sparse networks. Large link entropy values in the activation graph are related to the domination of redundant ensembles in late stages of development in dense networks. Results demonstrate differences between dense and sparse networks in terms of informational groups, pairwise relationships, and activation graphs. These differences suggest that variations in cell density may result in different functional specialization of nervous system tissue in vivo.Comment: 10 pages, 7 figure

Mudanças ambientais e interação humana na fachada atlântica ocidental

Fundação para a Ciência e a Tecnologia (FCT

Dressing Up the Kink

Many quantum field theoretical models possess non-trivial solutions which are stable for topological reasons. We construct a self-consistent example for a self-interacting scalar field--the quantum (or dressed) kink--using a two particle irreducible effective action in the Hartree approximation. This new solution includes quantum fluctuations determined self-consistently and nonperturbatively at the 1-loop resummed level and allowed to backreact on the classical mean-field profile. This dressed kink is static under the familiar Hartree equations for the time evolution of quantum fields. Because the quantum fluctuation spectrum is lower lying in the presence of the defect, the quantum kink has a lower rest energy than its classical counterpart. However its energy is higher than well-known strict 1-loop results, where backreaction and fluctuation self-interactions are omitted. We also show that the quantum kink exists at finite temperature and that its profile broadens as temperature is increased until it eventually disappears.Comment: 13 pages, latex, 3 eps figures; revised with yet additional references, minor rewordin