954 resultados para restriction of parameter space


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This paper introduces the discrete choice model-paradigm of Random Regret Minimization (RRM) to the field of environmental and resource economics. The RRM-approach has been very recently developed in the context of travel demand modelling and presents a tractable, regret-based alternative to the dominant choice-modelling paradigm based on Random Utility Maximization-theory (RUM-theory). We highlight how RRM-based models provide closed form, logit-type formulations for choice probabilities that allow for capturing semi-compensatory behaviour and choice set-composition effects while being equally parsimonious as their utilitarian counterparts. Using data from a Stated Choice-experiment aimed at identifying valuations of characteristics of nature parks, we compare RRM-based models and RUM-based models in terms of parameter estimates, goodness of fit, elasticities and consequential policy implications.

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The growth and saturation of Buneman-type instabilities is examined with a particle-in-cell (PIC) simulation for parameters that are representative for the foreshock region of fast supernova remnant shocks. A dense ion beam and the electrons correspond to the upstream plasma and a fast ion beam to the shock-reflected ions. The purpose of the 2D simulation is to identify the nonlinear saturation mechanisms, the electron heating and potential secondary instabilities that arise from anisotropic electron heating and result in the growth of magnetic fields. We confirm that the instabilities between both ion beams and the electrons saturate by the formation of phase space holes by the beam-aligned modes. The slower oblique modes accelerate some electrons, but they cannot heat up the electrons significantly before they are trapped by the faster beam-aligned modes. Two circular electron velocity distributions develop, which are centred around the velocity of each ion beam. They develop due to the scattering of the electrons by the electrostatic wave potentials. The growth of magnetic fields is observed, but their amplitude remains low.

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This article explores the dynamics of the space of exception at the borders of Europe in the Spanish enclave of Melilla, and the neighboring Moroccan city of Oujda. Building upon field research conducted in the spring of 2008, I ask how we can understand the political space of migration not simply as exceptional, but as shaped by the mobility of the irregular migrants moving outside of the frameworks, policies, and practices of the state. By privileging the migrant narrative and making use of Rancière's conception of politics as shaped by the demands of those who “have no part,” I suggest an alternative way of understanding the politics of exception and agency of non-citizens—that is, one of disruption and demands to open up powerful potentials for change in an otherwise rigid regime.

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This paper considers the recent proliferation of Belfast‘s =Quarters‘ as part of global trends towards the theming of city space, and as a response to the particular situation of Belfast at the beginning of the twenty-first century. It focuses on the Gaeltacht Quarter, a site that exemplifies the difficulty of applying the internationally popular model of cultural difference as a resource for the production of tourist revenue to the context of contested cities. The =quartering‘ of Belfast is represented as a response to post-industrial and post-conflict predicaments this city shares with many others. I consider how the urban context is sometimes exploited, as in exhortations to investors and tourists to contribute to Belfast‘s transformation from =a city of two halves‘ to =a city of seven quarters‘, and sometimes obscured, as in the recent re-invention of the Quarters as remnants of the city‘s distant past.

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Many cardiovascular diseases are characterised by the restriction of blood flow through arteries. Stents can be expanded within arteries to remove such restrictions; however, tissue in-growth into the stent can lead to restenosis. In order to predict the long-term efficacy of stenting, a mechanobiological model of the arterial tissue reaction to stress is required. In this study, a computational model of arterial tissue response to stenting is applied to three clinically relevant stent designs. We ask the question whether such a mechanobiological model can differentiate between stents used clinically, and we compare these predictions to a purely mechanical analysis. In doing so, we are testing the hypothesis that a mechanobiological model of arterial tissue response to injury could predict the long-term outcomes of stent design. Finite element analysis of the expansion of three different stent types was performed in an idealised, 3D artery. Injury was calculated in the arterial tissue using a remaining-life damage mechanics approach. The inflammatory response to this initial injury was modelled using equations governing variables which represented tissue-degrading species and growth factors. Three levels of inflammation response were modelled to account for inter-patient variability. A lattice-based model of smooth muscle cell behaviour was implemented, treating cells as discrete agents governed by local rules. The simulations predicted differences between stent designs similar to those found in vivo. It showed that the volume of neointima produced could be quantified, providing a quantitative comparison of stents. In contrast, the differences between stents based on stress alone were highly dependent on the choice of comparison criteria. These results show that the choice of stress criteria for stent comparisons is critical. This study shows that mechanobiological modelling may provide a valuable tool in stent design, allowing predictions of their long-term efficacy. The level of inflammation was shown to affect the sensitivity of the model to stent design. If this finding was verified in patients, this could suggest that high-inflammation patients may require alternative treatments to stenting.

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Architecture plays an important role in Andrei Tarkovsky’s films in defining the atmosphere of a space and memory of a place. This paper is a study of how the settings in Tarkovsky’s Solaris (1972) are used to provoke and convey feelings to the audience through architectonic space depicting the city, library, home and aspects of the home such as paintings and mirrors. The rooms depicted in Solaris (Fig. 1) are filled with symbolism and detail. They are imbued with a poetic quality rarely seen in cinema. The everyday places of city, library and home in Solaris are given an emotional depth not usually found in these spaces in reality. Solaris is an anomaly among Tarkovsky’s films in that the majority of the narrative takes place in an enclosed built set. Rarely do Tarkovsky spaces exert so much control over the actors’ movements within a meticulously designed and detailed set. This paper analyses how the director uses constructed sets in Solaris to confront our perception of memories, dreams and reality.
The intent of this study is to gain better understanding of the link between architecture and other art forms such as painting and cinema through spatial analysis. This study also relates to our imagination and how we perceive architectonic space portrayed through cinematic images. The architectural theory of Juhani Pallasmaa forms the basis of this paper.

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A new scheme, sketch-map, for obtaining a low-dimensional representation of the region of phase space explored during an enhanced dynamics simulation is proposed. We show evidence, from an examination of the distribution of pairwise distances between frames, that some features of the free-energy surface are inherently high-dimensional. This makes dimensionality reduction problematic because the data does not satisfy the assumptions made in conventional manifold learning algorithms We therefore propose that when dimensionality reduction is performed on trajectory data one should think of the resultant embedding as a quickly sketched set of directions rather than a road map. In other words, the embedding tells one about the connectivity between states but does not provide the vectors that correspond to the slow degrees of freedom. This realization informs the development of sketch-map, which endeavors to reproduce the proximity information from the high-dimensionality description in a space of lower dimensionality even when a faithful embedding is not possible.

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This article seeks to explore a notion of 'British outer space' in the mid 20th century with reference to the British Interplanetary Society and the works of Patrick Moore and Arthur C. Clarke. Geographies of outer space have been examined following early work by Denis Cosgrove on the Apollo space photographs. Cosgrove's work has encouraged a growing body of work that seeks to examine both the 'Earth from space' perspective as well as its reciprocal, 'space from Earth'. This article aligns itself with the latter viewpoint, in attempting to define a national culture of 'British outer space'. This is found to have an important connection with the British Interplanetary Society, founded in 1933 near Liverpool, which went on to influence the works of Patrick Moore, who edited the magazine Spaceflight and presented the television programme The Sky at Night, and Arthur C. Clarke, who became known as a science fiction writer through his early novels in the 1950s. The themes of audience participation and human destiny in outer space are examined in a close reading of these two case studies, and further engagement with cultures of outer space in geography is encouraged. © The Author(s) 2012.

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Regeneration projects take place within complex local policy environments and are also influenced by the global doctrine of neoliberalism, although the degree of influence will vary depending upon the historical, economic, social and political context. This article reviews and reflects upon the complexity of a neoliberalising policy environment in the regeneration of the divided city of Belfast. The territorial conflict in Northern Ireland has been expressed spatially and has thus affected urban regeneration. These issues are illustrated by a case study of the regeneration of the Crumlin Road Gaol and Girdwood Park in North Belfast, which sought to include both a neoliberalised economic development agenda and efforts to improve community relations through the promotion of shared space. The paper asks whether the management of community cohesion in cities experiencing conflict requires state intervention that at times goes beyond the ‘roll out’ and ‘roll back’ distinction found in neoliberal theory.

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The question of whether there is or was life on Mars has been one of the most pivotal since Schiaparellis' telescopic observations of the red planet. With the advent of the space age, this question can be addressed directly by exploring the surface of Mars and by bringing samples to Earth for analysis. The latter, however, is not free of problems. Life can be found virtually everywhere on Earth. Hence the potential for contaminating the Mars samples and compromising their scientific integrity is not negligible. Conversely, if life is present in samples from Mars, this may represent a potential source of extraterrestrial biological contamination for Earth. A range of measures and policies, collectively termed ‘planetary protection’, are employed to minimise risks and thereby prevent undesirable consequences for the terrestrial biosphere. This report documents discussions and conclusions from a workshop held in 2012, which followed a public conference focused on current capabilities for performing life-detection studies on Mars samples. The workshop focused on the evaluation of Mars samples that would maximise scientific productivity and inform decision making in the context of planetary protection. Workshop participants developed a strong consensus that the same measurements could be employed to effectively inform both science and planetary protection, when applied in the context of two competing hypotheses: 1) that there is no detectable life in the samples; or 2) that there is martian life in the samples. Participants then outlined a sequence for sample processing and defined analytical methods that would test these hypotheses. They also identified critical developments to enable the analysis of samples from Mars.

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In this paper we address the idea of ‘legal but corrupt’ through a discussion of two cases: abuse scandals in the Irish Catholic Church and the financial services industry in the wake of the Global Financial Crisis. We identify two important dynamics that generated the scandals: that they were driven by strong and stable groups existing within a peculiar kind of ‘accountability space’ that we describe as ‘monastic’ and that those groups persisted with tacit or explicit support from the state. ‘Legal but corrupt’ is, we argue, a matter of insider incomprehension sustained by the ceding of sovereignty over some aspect of social or economic life.

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‘A free Ireland would drain the bogs, would harness the rivers, would plant the wastes, would nationalise the railways and the waterways, would improve agriculture, would protect fisheries, would foster industries, would promote commerce, and beautify the cities …’ (Padraig Pearse, ‘From a Hermitage’, 1913)

Somewhat unusually in his often romantic writings Padraig Pearse – poet, pedagogue and revolutionary – chose to describe the future of an independent Ireland in terms of infrastructure and technological processes. Terence Brown’s locating of this excerpt at the beginning his seminal work Ireland: A Social and Cultural History 1922-2002 highlights the simultaneous and interlinking construction of both a new physical and cultural landscape for an independent modern nation. Lacking any significant industrial complex, the construction of new infrastructures in Ireland was seen throughout the 20th century as a key element in the building of the new State, just as the adoption of an international style modernism in architecture was perceived as a way to escape the colonial past. For Paul N. Edwards modernity and infrastructure are intimately connected.

‘infrastructures simultaneously shape and are shaped – in other words, co-construct – the condition of modernity. By linking macro, meso, and micro scales of time, space and social organisation, they form the stable foundation of modern social worlds’ (2003: 186).
Simultaneously omnipresent and invisible – infra means beneath – Edwards also points out that infrastructure tends only to become apparent when it is either new or broken. Interpreting the meso scale as being that of the building, this session calls for papers that critically and analytically investigate aspects of the architectures of infrastructure in 20th-century Ireland. Like the territory they explore these papers may range across scales to oscillate between a concern for the artefact and its physical landscape, and the larger, often hidden systems and networks that co-define this architecture.

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This study aimed to assess the effect of the number of straw bales (SBs) provided on the behaviour and leg health of commercial broiler chickens. Houses containing ~23 000 broiler chickens were assigned to one of two treatments: (1) access to 30 SBs per house, ‘30SB’ or (2) access to 45 SB per house, ‘45SB’. This equated to bale densities of 1 bale/44 m2 and 1 bale/29 m2 of floor space within houses, respectively. Treatments were applied in one of two houses on a commercial farm, and were replicated over six production cycles. Both houses had windows and were also artificially lit. Behaviour was observed in weeks 3 to5 of the cycle. This involved observations of general behaviour and activity, gait scores (0: perfect to 5: unable to walk) and latency to lie (measured in seconds from when a bird had been encouraged to stand). Production performance and environmental parameters were also measured. SB density had no significant effect on activity levels (P>0.05) or walking ability (P>0.05). However, the average latency to lie was greater in 30SB birds compared with 45SB birds (P<0.05). The incidence of hock burn and podo dermatitis, average BW at slaughter and levels of mortality and culling were unaffected by SB density (P>0.05). The results from this study suggest that increasing SB levels from 1 bale/44 m2 to 1 bale/29 m2 floor space does not lead to significant improvements in the welfare of commercial broiler chickens in windowed houses.

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The notion of privacy represents a central criterion for both indoor and outdoor social spaces in most traditional Arab settlements. This paper investigates privacy and everyday life as determinants of the physical properties of the built and urban fabric and will study their impact on traditional settlements and architecture of the home in the contemporary Iraqi city. It illustrates the relationship between socio-cultural aspects of public/private realms using the notion of the social sphere as an investigative tool of the concept of social space in Iraqi houses and local communities (Mahalla). This paper reports that in spite of the impact of other factors in articulating built forms, privacy embodies the primary role under the effects of Islamic rules, principles and culture. The crucial problem is the underestimation of traditional inherited values through opening social spaces to the outside that giving unlimited accesses to the indoor social environment creating many problems with regard to privacy and communal social integration.