883 resultados para Symbolism in architecture
Resumo:
In this paper we follow the BOID (Belief, Obligation, Intention, Desire) architecture to describe agents and agent types in Defeasible Logic. We argue, in particular, that the introduction of obligations can provide a new reading of the concepts of intention and intentionality. Then we examine the notion of social agent (i.e., an agent where obligations prevail over intentions) and discuss some computational and philosophical issues related to it. We show that the notion of social agent either requires more complex computations or has some philosophical drawbacks.
Resumo:
A hydraulic jump is characterized by strong energy dissipation and mixing, large-scale turbulence, air entrainment, waves and spray. Despite recent pertinent studies, the interaction between air bubbles diffusion and momentum transfer is not completely understood. The objective of this paper is to present experimental results from new measurements performed in rectangular horizontal flume with partially-developed inflow conditions. The vertical distributions of void fraction and air bubbles count rate were recorded for inflow Froude number Fr1 in the range from 5.2 to 14.3. Rapid detrainment process was observed near the jump toe, whereas the structure of the air diffusion layer was clearly observed over longer distances. These new data were compared with previous data generally collected at lower Froude numbers. The comparison demonstrated that, at a fixed distance from the jump toe, the maximum void fraction Cmax increases with the increasing Fr1. The vertical locations of the maximum void fraction and bubble count rate were consistent with previous studies. Finally, an empirical correlation between the upper boundary of the air diffusion layer and the distance from the impingement point was provided.
Resumo:
For centuries, hydraulic engineers were at the forefront of science. The last forty years marked a change of perception in our society with a focus on environmental sustainability and management, particularly in developed countries. Herein, the writer illustrates his strong belief that the future of hydraulic engineering lies upon a combination of innovative engineering, research excellence and higher education of quality. This drive continues a long tradition established by eminent scholars like Arthur Thomas IPPEN, John Fisher KENNEDY and Hunter ROUSE.
Resumo:
This paper will examine attitudes to eclectic stylistic borrowing in Japan in the twentieth century in light of the concept of authenticity. I am particularly interested in how an earlier claim correlating European modernist and traditional Japanese architecture continues to colour conceptions about what is an 'authentic' response for Japanese architects to make to contemporary conditions. Non-Western and vernacular architectures generally have been the repository for touristic desires for regional authenticity and difference. Yet Japan's unique role in the development of modernist architecture has given a peculiar intensity to the demand for its architecture to resist a perceived postmodern decadence.
Resumo:
Published in the final months of 1891, Architecture, Mysticism and Myth was the first architectural treatise written by the late nineteenth-century English architect and theorist William Richard Lethaby (1857-1931).' Documenting the characteristic attributes of the architectural myth of the "temple idea", and its presence amongst architectures of multiple ancient cultures, the text was endowed with a distinctly historical tone. In examining the motives behind myth, which Lethaby defined as the interaction and reaction between the natural universe and the built environment, Lethaby also injected a series of theoretical considerations into the text. It is clear that Lethaby's interest in the temple idea was not limited to its curious, prolific presence in past architectures, hut also embraced a consideration of what lessons the temple idea may contribute to the struggle of the late nineteenth-century English architect to define an "art of the future".
Resumo:
This paper considers the relationship between the recent historiography (of the last quarter century) of “New Zealand architecture” and the historical notion of “New Zealand-ness” invoked in contemporary architecture. It argues that a more recent programmatic uptake of post-War discussions on national identity and regional specificity has fed the tendencies of practicing architects to defer to history in rhetorical defences of their work: the beach-side mansion as a contemporary expression of the 1950s bach; a formal modernism divorced from the social discourse adherent to the historical moment that it “restates”; and so on. The paper will consider instances in the historiography of New Zealand architecture where historians have compounded, consciously or accidentally, a problem that is systemic to the uses made by architects of historical knowledge (in the most general examples), identifying the difficulties of relying upon the tentative conclusions of an under-studied field in developing principles of contemporary architectural practice under the banners of New Zealand-ness, regionalism, or localism, or with reference to icons of New Zealand architectural history. At the heart of this paper is a reflection on historiographical responsibility in presenting knowledge of a national past to an audience that is eager to transform that knowledge into principles of contemporary production. What, the paper asks, is the historical basis for speaking of a New Zealand architecture? Can we speak of a national history of architecture distinct from a regional history, or from an international history of architecture?
Resumo:
Plant architecture has been neglected in most studies of biomass allocation in crops. To help redress this situation for grain sorghum (Sorghum bicolor (L.) Moench), we used a 3D digitiser to measure the dimensions and orientations of vegetative and reproductive structures and derived thermal time-based functions for architectural changes during morphogenesis. Our plants, which were grown in a greenhouse, controlled environment cabinets and the field, covered a large, three-fold, size range when mature. This allowed us to detect some general architectural relationships and to fit morphogenetic functions common across the size range we observed. For example, the relationship between the lengths of successive fully-expanded leaves within a plant was nearly constant for all plants. The lengths of existing leaf blades were accurate predictors of the lengths of up to six subsequently-formed blades in our plants. Similar constant relationships were detected for internode lengths in the panicle and for heights above ground of the collars of successive leaves, even though these traits varied a lot between growth conditions. We suggest that such architectural relationships may be used to link the effect of previous growth conditions to future growth potential, and in that way to predict future partitioning. Our results provide the basis for a preliminary model of sorghum morphogenesis which could eventually become useful in conjunction with crop models by allowing resource acquisition to be related to changes in plant architecture during development. (C) 1999 Elsevier Science B.V. All rights reserved.
Resumo:
Traditional field sampling approaches for ecological studies of restored habitat can only cover small areas in detail, con be time consuming, and are often invasive and destructive. Spatially extensive and non-invasive remotely sensed data can make field sampling more focused and efficient. The objective of this work was to investigate the feasibility and accuracy of hand-held and airborne remotely sensed data to estimate vegetation structural parameters for an indicator plant species in a restored wetland. High spatial resolution, digital, multispectral camera images were captured from an aircraft over Sweetwater Marsh (San Diego County, California) during each growing season between 1992-1996. Field data were collected concurrently, which included plant heights, proportional ground cover and canopy architecture type, and spectral radiometer measurements. Spartina foliosa (Pacific cordgrass) is the indicator species for the restoration monitoring. A conceptual model summarizing the controls on the spectral reflectance properties of Pacific cordgrass was established. Empirical models were developed relating the stem length, density, and canopy architecture of cordgrass to normalized-difference-vegetation-index values. The most promising results were obtained from empirical estimates of total ground cover using image data that had been stratified into high, middle, and low marsh zones. As part of on-going restoration monitoring activities, this model is being used to provide maps of estimated vegetation cover.
Resumo:
Confocal scanning laser microscopic observations were made on live chloroplasts in intact cells and on mechanically isolated, intact chloroplasts. Chlorophyll fluorescence was imaged to observe thylakoid membrane architecture. C-3 plant species studied included Spinacia oleracea L., Spathiphyllum sp. Schott, cv. 'Mauna Loa', and Pisum sativum L. C-4 plants were also investigated: Saccharum officinarum L., Sorghum bicolor L. Moench, Zea mays L. and Panicum miliaceum L. Some Spinacia chloroplasts were treated with 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) to enhance or sodium dithionite (SD) to reduce the photosystem II fluorescence signal. Confocal microscopy images of C-3 chloroplasts differed from electron microscopy pictures because they showed discrete spots of bright fluorescence with black regions between them. There was no evidence of fluorescence from stroma thylakoids. The thylakoid membrane system at times appeared to be string-like, with brightly fluorescing grana lined up like beads. C-4 bundle sheath chloroplasts were imaged from three different types of C-4 plants. Saccharum and Sorghum bundle sheath chloroplasts showed homogeneous fluorescence and were much dimmer than mesophyll chloroplasts. Zea had rudimentary grana, and dim, homogeneous intergrana fluorescence was visualised. Panicum contained thylakoids similar in appearance and string-like arrangement to mesophyll chloroplasts. Isolated Pisum chloroplasts, treated with a drop of 5 mM MgCl2 showed a thylakoid membrane system which appeared to be unravelling. Spongy mesophyll chloroplasts of Spinacia treated with 5 mM sodium dithionite showed a granal thylakoid system with distinct regions of no fluorescence. A time-series experiment provided evidence of dynamic membrane rearrangements over a period of half an hour.
Resumo:
The 3-dimensionaI structure determination of rat phenylalanine hydroxylase (PAH) has identified potentially important amino acids lining the active site cleft with the majority of these having hydrophobic side-chains including several with aromatic side chains. Here we have analyzed the effect on rat PAH enzyme kinetics of in vitro mutagenesis of a number of these amino acids lining the PAH active site. Mutation of F299, Y324, F331, and Y343 caused a significant decrease in enzyme activity but no change in the K-m for substrate or cofactor. me conclude that these aromatic residues are essential for activity but are not significantly involved in binding of the substrate or cofactor. in contrast the PAH mutant, S349T, showed an 18-fold increase in K-m for phenylalanine, showing the first functional evidence that this residue was binding at or near the phenylalanine binding site. This confirms the recently published model for the binding of phenylalanine to the PAH active site that postulated S349 interacts with the amino group on the main chain of the phenylalanine molecule. This result differs with that found for the equivalent mutation (S395T), in the closely related tyrosine hydroxylase, which had no effect on substrate K-m, showing that while the architecture of the two active sites are very similar the amino acids that bind to the respective substrates are different. (C) 2000 Academic Press.
Resumo:
Diadromous freshwater shrimps are exposed to brackish water both as an obligatory part of their larval life cycle and during adult reproductive migration; their well-developed osmoregulatory ability is crucial to survival in such habitats. This study examines gill microsomal Na,K-ATPase (K-phosphatase activity) kinetics and protein profiles in the freshwater shrimp Macrobrachium amazonicum when in fresh water and after 10-days of acclimation to brackish water (21 parts per thousand salinity), as well as potential routes of Na(+) uptake across the gill epithelium in fresh water. On acclimation, K-phosphatase activity decreases 2.5-fold, Na,K-ATPase alpha-subunit expression declines, total protein expression pattern is markedly altered, and enzyme activity becomes redistributed into different density membrane fractions, possibly reflecting altered vesicle trafficking between the plasma membrane and intracellular compartments. Ultrastructural analysis reveals an intimately coupled pillar cell-septal cell architecture and shows that the cell membrane interfaces between the external medium and the hemolymph are greatly augmented by apical pillar cell evaginations and septal cell inviginations, respectively. These findings ire discussed regarding the putative movement of Na(+) across the pillar cell interfaces and into the hemolymph via the septal cells, powered by the Na,K-ATPase located in their invaginations. (C) 2008 Elsevier Inc. All rights reserved.
Resumo:
Statement of the study: Based on data from ecological and analytic epidemiological studies, we have proposed that low prenatal vitamin D is a candidate risk-modifying factor for schizophrenia. Previously, we demonstrated that low prenatal vitamin D adversely affected brain development in neonatal rats (Eyles et al, 2003). Here we examine the impact of both prenatal and early life hypovitaminosis D on various outcomes in the adult rat brain. Methods: Female Sprague-Dawley rats were made vitamin D deficient via the use of a special diet (Dyets CA) and lighting conditions that excluded UVB radiation. Animals were kept under these conditions for 6 weeks then mated with males kept under normal conditions. Vitamin deplete dams were kept under these conditions during pregnancy. Offspring from two test groups were examined. Offspring were either reared with dams repleted with vitamin D at birth or remained under deplete conditions till weaning. Both test groups were weaned under normal vitamin D conditions and remained so till testing at adulthood. We compared the brains of adult offspring kept under both test conditions with animals from control environments. Summary of results: We found a significant persistent dose-related increase in lateral ventricle volume and alterations in anterior cingulate and prefrontal cortical cell densities (consistent with the known prodifferentiation properties of this steroid). In both test groups we observed a reduced expression of NGF as well as a down-regulation of transcripts coding for GABAA alpha 4 receptor and two neuronal structural elements; MAP2 and Neurofilament L. Conclusion: These findings provide further evidence that vitamin D is involved in brain development. An increase in prefrontal cortical cell density, a reduction neuronal structural elements and persistent ventriculomegaly are all common anatomical findings in the brains of patients with schizophrenia. The specific reduction in transcripts for neuronal structural proteins but not GFAP is also in accordance with the proposal that frontal cortical architecture in schizophrenia reflects a reduction in connectivity rather than a reduction in glial processes(Goldman-Rakic and Selemon, 1997). These findings confirm the biological plausibility of early life hypovitaminosis D as a risk factor for schizophrenia.