304 research outputs found
Local seismic cultures: the use of timber frame structures in the south of Portugal
Given the fact that using timber frame structures has proven to improve the seismic behavior of
vernacular architecture, as has been reported in past earthquakes in many countries, its
preservation as a traditional earthquake resistant practice is important. This paper firstly intends
to evaluate whether the use of timber frames as a traditional seismic resistant technique for
vernacular architecture in the South of Portugal, traditionally a seismic region, is still active.
Secondly, the city of Vila Real de Santo António was selected as a case study because it also
followed a Pombaline development contemporary to the reconstruction of Lisbon. The plan
included the provision of timber frame partition walls for some of the buildings and, thus, an
overview of the type of constructions originally conceived is provided. Finally, the alterations
done in the original constructions and the current state of the city center are described and the
effect of these changes on the seismic vulnerability of the city is discussed.The authors wish to express their gratitude to the Portuguese Science and Technology Foundation (FCT) for the scholarship granted in the scope of the research project 'SEISMIC-V-Vernacular Seismic Culture in Portugal' (PTDC/ATP-AQI/3934/2012)
IL-17A and serum amyloid A are elevated in a cigarette smoke cessation model associated with the persistence of pigmented macrophages, neutrophils and activated NK cells
While global success in cessation advocacy has seen smoking rates fall in many developed countries, persistent lung inflammation in ex-smokers is an increasingly important clinical problem whose mechanistic basis remains poorly understood. In this study, candidate effector mechanisms were assessed in mice exposed to cigarette smoke (CS) for 4 months following cessation from long term CS exposure. BALF neutrophils, CD4+ and CD8+ T cells and lung innate NK cells remained significantly elevated following smoking cessation. Analysis of neutrophil mobilization markers showed a transition from acute mediators (MIP-2α, KC and G-CSF) to sustained drivers of neutrophil and macrophage recruitment and activation (IL-17A and Serum Amyoid A (SAA)). Follicle-like lymphoid aggregates formed with CS exposure and persisted with cessation, where they were in close anatomical proximity to pigmented macrophages, whose number actually increased 3-fold following CS cessation. This was associated with the elastolytic protease, MMP-12 (macrophage metallo-elastase) which remained significantly elevated post-cessation. Both GM-CSF and CSF-1 were significantly increased in the CS cessation group relative to the control group. In conclusion, we show that smoking cessation mediates a transition to accumulation of pigmented macrophages, which may contribute to the expanded macrophage population observed in COPD. These macrophages together with IL-17A, SAA and innate NK cells are identified here as candidate persistence determinants and, we suggest, may represent specific targets for therapies directed towards the amelioration of chronic airway inflammation
Deletion and replacement of the mouse adult beta-globin genes by a "plug and socket" repeated targeting strategy.
We describe a two-step strategy to alter any mouse locus repeatedly and efficiently by direct positive selection. Using conventional targeting for the first step, a functional neo gene and a nonfunctional HPRT minigene (the "socket") are introduced into the genome of HPRT- embryonic stem (ES) cells close to the chosen locus, in this case the beta-globin locus. For the second step, a targeting construct (the "plug") that recombines homologously with the integrated socket and supplies the remaining portion of the HPRT minigene is used; this homologous recombination generates a functional HPRT gene and makes the ES cells hypoxanthine-aminopterin-thymidine resistant. At the same time, the plug provides DNA sequences that recombine homologously with sequences in the target locus and modifies them in the desired manner; the plug is designed so that correctly targeted cells also lose the neo gene and become G418 sensitive. We have used two different plugs to make alterations in the mouse beta-globin locus starting with the same socket-containing ES cell line. One plug deleted 20 kb of DNA containing the two adult beta-globin genes. The other replaced the same region with the human beta-globin gene containing the mutation responsible for sickle cell anemia
Seismic behaviour of traditional timber frame walls: experimental results on unreinforced walls
Timber frame buildings are well known as an efficient seismic resistant structure
and they are used worldwide. Moreover, they have been specifically adopted in codes and
regulations during the XVIII and XIX centuries in the Mediterranean area. These structures
generally consist of exterior masonry walls with timber elements embedded which tie the
walls together and internal walls which have a timber frame with masonry infill and act as
shearwalls. In order to preserve these structureswhich characterizemany cities in theworld it
is important to better understand their behaviour under seismic actions. Furthermore, historic
technologies could be used even in modern constructions to build seismic resistant buildings
using more natural materials with lesser costs. Generally, different types of infill could be
applied to timber frame walls depending on the country, among which brick masonry, rubble
masonry, hay and mud. The focus of this paper is to study the seismic behaviour of the walls
considering different types of infill, specifically: masonry infill, lath and plaster and timber
frame with no infill. Static cyclic tests have been performed on unreinforced timber frame
walls in order to study their seismic capacity in terms of strength, stiffness, ductility and
energy dissipation. The tests showed how in the unreinforced condition, the infill is able to
guarantee a greater stiffness, ductility and ultimate capacity of the wall.The authors would like to acknowledge Eng. Filipe Ferreira and A.O.F. (Augusto Oliveira Ferreira &
C Lda.) for their expertise and collaboration in the construction of the wall specimens.
The first author would also like to acknowledge the Portuguese Science and Technology
Foundation (FCT) for its financial support through grant SFRH / BD / 61908 / 2009
Seismic performance evaluation of traditional timber Hımış frames: capacity spectrum method based assessment
Timber constructions have been widely suggested to be seismically resistant based on post-disaster reconnaissance studies. This observation has, however, remained to a large extent anecdotal due to the lack of experimental work supporting it, especially for certain timber architectural forms, including traditional timber frame “hımış” structures. To fill this gap, the authors carried out an extensive full-scale testing scheme using frames of various geometrical configurations, tested under reverse-cyclic lateral loading with/without infill (brick and adobe) or cladding (bağdadi and şamdolma) (Aktas et al. in Earthq Spectra 30(4):1711–1732, 2014a, b). The tests concluded that hımış frames had high energy dissipation capabilities due mostly to nailed connections. Infill/cladding significantly helped improve stiffness and lateral load strength of the frames, and timber type did not seem to make a remarkable impact on the overall behaviour. The current paper, on the other hand, uses test data to calculate capacity/demand ratios based on capacity spectrum method and Eurocode 8 to elaborate more on the performance of “hımış” structures under seismic loading. The obtained results are discussed to draw important conclusions with regards to how frame geometry and infill/cladding techniques affect the overall performance
A continuous culture of pluripotent fetal hepatocytes derived from the 8-day epiblast of the pig
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