2,659 research outputs found
Achados metálicos de cobre no Baixo Vouga (Centro-Norte de Portugal)
O objetivo deste trabalho é o de dar a conhecer dois objetos metálicos, à base de cobre, encontrados em contextos arqueológicos distintos do curso inferior do rio Vouga e desta forma contribuir para o estudo das primeiras produções metalúrgicas na fachada ocidental do Centro-Norte português.
O primeiro artefacto, um punhal com chanfraduras na zona de encaixe, foi detetado no sítio da Tapada do Espinheiro, freguesia de Sepins, concelho de Cantanhede, num terraço localizado a NW da plataforma de Murtede-Cordinhã, sobranceira à Vala Real/rio da Tapada (rio da Ponte), tributária do rio Cértima, afluente da margem sul do Vouga. O achado, detetado em trabalhos de prospeção, inseria-se numa área com cerca de 1.000 m2 onde ocorriam manchas de terra escura, concentração de cerâmica, de artefactos em pedra polida e talhada e alguns calhaus e blocos calcários resultantes da destruição de estruturas pétreas.
A segunda peça, um machado plano, foi encontrado no topo da referida plataforma, a norte da freguesia de Sepins, concelho de Cantanhede, numa estação arqueológica de grandes dimensões sobranceira ao rio da Ponte, afluente do Cértima.
Em ambos os contextos há fragmentos cerâmicos profusamente decorados com decorações incisas metopadas de tipo Penha, típicos do Calcolítico do Noroeste português, assim como decorações penteadas e espinhadas, comuns no Calcolítico do Nordeste e no Calcolítico e Inícios da Idade do Bronze do Alto Douro e da Beira Alta, balizas cronológicas onde estas peças se poderão inserir.
Ao contrário do acervo cerâmico que indicia contactos com o Noroeste Peninsular e áreas mais interiores da bacia do Mondego, o punhal de chanfradura, de tradição meridional calcolítica, permite admitir que o curso inferior da bacia do Vouga foi uma zona charneira no encontro de diferentes tradições culturais, durante o III milénio a.C.
A composição química dos objectos metálicos, determinada por espectrometria de fluorescência de raios X, contribui para a caracterização das primeiras produções metalúrgicas na fachada ocidental Centro – Norte do país, bem como a sua contextualização na arqueometalurgia peninsular.Fundação para a Ciência e a Tecnologia (FCT
Orientalizing Artifacts from Fraga dos Corvos Rock Shelter in North Portugal
An unusual set of metallic artifacts with orientalizing character, attributed to a late period of the Late Bronze Age (LBA), was found in a shelter in Northern Portugal. Conventional and micro-energy dispersive X-ray fluorescence (XRF) analyses have been performed to determine the metal
composition. The microstructures of some artifacts have also been studied under optical and scanning electron microscope (SEM). The results show that most of the items are made of a copper–tin alloy with low lead content and show a recrystallized grained microstructure.Fundação para a Ciência e Tecnologi
Salt weathering of natural stone: a review of comparative laboratory studies
Natural stone is an important component of historical heritage (buildings and art objects such as sculptures or rock engravings), and it is still widely used in contemporary works. Soluble salts are the main erosive agent in the built environment, and we review here comparative studies that subject the same rock type to testing with different salt solutions. The results mostly support the accepted notion of the major impact of sodium sulphate, although there are some exceptions. The effects of sodium chloride and calcium sulphate deserve specific discussion given field information on the relevance of these specific salts in the built environment. We relate the information collected to the issues of risk assessment (considering both geochemical conditions and salt effects) and conservation interventions (highlighting the interest of tests that do not produce damage to susceptible materials) and present some methodological suggestions to avoid a case study culture.The Lab2PT-Landscapes, Heritage and Territory laboratory—UIDB/04509/2020
is supported by the Portuguese FCT—“Fundação para a Ciência e a Tecnologia”. The authors
also gratefully acknowledge the support of the CERENA (funded by a strategic project of the FCTUIDB/04028/2020) and the LAMPIST of the DECivil, Instituto Superior Técnico, University of
Lisbon, Portugal. The University Institute of Geology of the University of A Coruña (Spain) receives
support from the Xunta de Galicia from the program “Consolidación y estructuración de unidades
de investigación competitivas: Grupos de potencial de crecimiento” (ED431B 2018/47) and Redes de
investigación (R2017/008)
Simulation of a robotic bird
In this paper it is studied the dynamics of the robotic bird. The system performances are analyzed in terms of time response and robustness. It is study the relation between the angle of attack and the velocity of the bird, the tail influence, the gliding flight and the flapping flight. In this model, a bird flies by the wind beat motion or using its tail down. The results are positive for the construction of flying robots. The development of computational simulation based on the dynamic of the robotic bird that should allow testing strategies and algorithms of control.N/
A Hybrid Adaptive Routing Algorithm for Event-Driven Wireless Sensor Networks
Routing is a basic function in wireless sensor networks (WSNs). For these networks, routing algorithms depend on the characteristics of the applications and, consequently, there is no self-contained algorithm suitable for every case. In some scenarios, the network behavior (traffic load) may vary a lot, such as an event-driven application, favoring different algorithms at different instants. This work presents a hybrid and adaptive algorithm for routing in WSNs, called Multi-MAF, that adapts its behavior autonomously in response to the variation of network conditions. In particular, the proposed algorithm applies both reactive and proactive strategies for routing infrastructure creation, and uses an event-detection estimation model to change between the strategies and save energy. To show the advantages of the proposed approach, it is evaluated through simulations. Comparisons with independent reactive and proactive algorithms show improvements on energy consumption
Editor’s Note
[EN] Under the auspices of IMACSS –International Martial Arts and Combat Sports Scientific Society..
Achados metálicos de cobre no baixo Vouga (Centro-Norte de Portugal)
O objetivo deste trabalho é o de dar a conhecer dois objetos metálicos, à base de cobre,
encontrados em contextos arqueológicos distintos do curso inferior do rio Vouga e desta
forma contribuir para o estudo das primeiras produções metalúrgicas na fachada ocidental
do Centro-Norte português.
O primeiro artefacto, um punhal com chanfraduras na zona de encaixe, foi detetado no sítio
da Tapada do Espinheiro, freguesia de Sepins, concelho de Cantanhede, num terraço localizado
a NW da plataforma de Murtede-Cordinhã, sobranceira à Vala Real (rio da Tapada ou da
Ponte), tributária do rio Cértima, afluente da margem sul do Vouga. O achado, detetado em
trabalhos de prospeção, inseria-se numa área com cerca de 1 000 m2 onde ocorriam manchas
de terra escura, concentração de cerâmica, de artefactos em pedra polida e talhada e alguns
calhaus e blocos calcários resultantes da destruição de estruturas pétreas.
A segunda peça, um machado plano, foi encontrado no topo da referida plataforma, a norte
da freguesia de Sepins, concelho de Cantanhede, numa estação arqueológica de grandes
dimensões sobranceira ao rio da Ponte, afluente do Cértima.
Em ambos os contextos há fragmentos cerâmicos profusamente decorados com decorações
incisas metopadas de tipo Penha, típicos do Calcolítico do Noroeste português, assim como
decorações penteadas e espinhadas, comuns no Calcolítico do Nordeste e no Calcolítico e
Inícios da Idade do Bronze do Alto Douro e da Beira Alta, balizas cronológicas onde estas
peças se poderão inserir.
Ao contrário do acervo cerâmico que indicia contactos com o Noroeste Peninsular e áreas
mais interiores da bacia do Mondego, o punhal de chanfradura, de tradição meridional
calcolítica, permite admitir que o curso inferior da bacia do Vouga foi uma zona charneira
no encontro de diferentes tradições culturais, durante o III milénio a.C.
A composição química dos objetos metálicos, determinada por espectrometria de fluorescência
de raios X, contribui para a caraterização das primeiras produções metalúrgicas na fachada
ocidental Centro – Norte do país, bem como a sua contextualização na arqueometalurgia
peninsular.The aim of this work is to present two metallic objects found in archaeological contexts
in the lower course of the Vouga river contributing to the study of the first metallurgical
productions at the western façade of the Central-North of Portugal.
The first artefact, an early dagger, was found at the site of Tapada do Espinheiro, in the
Sepins surroundings, county of Cantanhede, at a terrace of the NW side of the Sepins plateau,
overlooking the Vala Real (Ponte river), tributary of Cértima river, a tributary of the Vouga
basin. The finding was recovered during field work, in an area of about 1 000 m2
, within
which occurs patches of dark earth, concentrations of pottery, carved and polished stone
artefacts and some pebbles and blocks that result from the destruction of stone structures.
The second object, a flat axe, was found in Pedrulhais, in the Sepins surroundings, county
of Cantanhede, at a large archaeological site or enclusure located in the Sepins plateau
overlooking the Ponte river, a tributary of Cértima, about 1.5 km East of the first.
In both contexts there are pottery fragments of the “Penha type” profusely decorated, typical
of the Chalcolithic of the Northwest of Portugal, as well as pottery with combed and spines
decorations, common in the Chalcolithic of the Northeast of Portugal and in the Chalcolithic
and Early Bronze Age in Alto Douro and Beira Alta regions, chronological milestones where
these pieces could be inserted. Although the ceramic collection suggests contacts with the Northwest of Iberian Peninsula
and areas further inland of the Mondego river, the dagger finds similarities to the
Chalcolithic Southern tradition. This might be an indication that the lower course of the
Vouga basin could have been an area where different cultural traditions meet during the
III millennium BC.
The chemical composition of the metallic objects, determined by energy dispersive X-ray
fluorescence spectrometry, contributes to the characterization of the first metal productions
in the west façade of the Central-North of Portugal, allowing the contextualization of these
findings among the Iberian ancient metallurgy.Este trabalho foi realizado no âmbito dos projetos Metalurgia Primitiva no
Território Português – EARLYMETAL (PTDC/HIS-ARQ/110442/2008) e Paisagens
da Idade do Bronze no Ocidente Peninsular (SFRH/BSAB/986/10), financiados pela
Fundação para a Ciência e a Tecnologia (FCT), e a bolsa SFRH/BPD/73245/2010,
também financiada pela FCT.info:eu-repo/semantics/publishedVersio
Dexamethasone prevents granulocyte-macrophage colony-stimulating factor-induced nuclear factor-kappaB activation, inducible nitric oxide synthase expression and nitric oxide production in a skin dendritic cell line.
AIMS: Nitric oxide (NO) has been increasingly implicated in inflammatory skin diseases, namely in allergic contact dermatitis. In this work, we investigated the effect of dexamethasone on NO production induced by the epidermal cytokine granulocyte-macrophage colony-stimulating factor (GM-CSF) in a mouse fetal skin dendritic cell line. METHODS: NO production was assessed by the method of Griess. Expression of the inducible isoform of nitric oxide synthase (iNOS) protein was evaluated by western blot analysis and immunofluorescence microscopy. Western blot analysis was also performed to evaluate cytosolic IkappaB-alpha (IkappaB-alpha) protein levels. The electrophoretic mobility shift assay was used to evaluate the activation or inhibition of nuclear factor kappa B (NF-kappaB). RESULTS: GM-CSF induced iNOS expression and NO production, and activated the transcription factor NF-kappaB. Dexamethasone inhibited, in a dose-dependent manner, NO production induced by GM-CSF. Addition of dexamethasone to the culture, 30 min before GM-CSF stimulation, significantly inhibited the cellular expression of iNOS. Dexamethasone also inhibited GM-CSF-induced NF-kappaB activation by preventing a significant decrease on the IkappaB-alpha protein levels, thus blocking NF-kappaB migration to the nucleus. CONCLUSIONS: The corticosteroid dexamethasone inhibits GM-CSF-induced NF-kappaB activation, iNOS protein expression and NO production. These results suggest that dexamethasone is a potent inhibitor of intracellular events that are involved on NO synthesis, in skin dendritic cells
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