26 resultados para Trees in cities

em QUB Research Portal - Research Directory and Institutional Repository for Queen's University Belfast


Relevância:

100.00% 100.00%

Publicador:

Resumo:

It is commonly believed that trees were absent in Scandinavia during the last glaciation and first recolonized the Scandinavian Peninsula with the retreat of its ice sheet some 9000 years ago. Here, we show the presence of a rare mitochondrial DNA haplotype of spruce that appears unique to Scandinavia and with its highest frequency to the west—an area believed to sustain ice-free refugia during most of the last ice age. We further show the survival of DNA from this haplotype in lake sediments and pollen of Trøndelag in central Norway dating back ~10,300 years and chloroplast DNA of pine and spruce in lake sediments adjacent to the ice-free Andøya refugium in northwestern Norway as early as ~22,000 and 17,700 years ago, respectively. Our findings imply that conifer trees survived in ice-free refugia of Scandinavia during the last glaciation, challenging current views on survival and spread of trees as a response to climate changes.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Birks et al. question our proposition that trees survived the Last Glacial Maximum (LGM) in Northern Scandinavia. We dispute their interpretation of our modern genetic data but agree that more work is required. Our field and laboratory procedures were robust; contamination is an unlikely explanation of our results. Their description of Endletvatn as ice-covered and inundated during the LGM is inconsistent with recent geological literature.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The paper addresses two connected questions: firstly, in what ways might ‘public’ and ‘private’ spaces in cities be gendered; and secondly, what might this mean for the possibilities for complex forms of civility in a divided city such as Belfast? The specific focus on gendered dynamics of entitlement to inhabit urban space in this paper begins with some consideration of debates about the quality and experience of everyday life in cities, and the emergence of commonsense notions of ‘public’ and ‘private’ behaviour. Following this, key research concerned with the gendered dynamics of claimed collective, and particularly national, identities are outlined, in order to consider the significance of this literature for any study of the gender dynamics of life in a contested political context such as Belfast.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Aim Species generally become rarer and more patchily distributed as the margins of their ranges are approached. We predicted that in such marginal sites, tree species would tend to occur where some key environmental factors are at particularly favourable levels, compensating in part for the low overall suitability of marginal sites.

Location The article considers the spatial distributions of trees in Southeast Alaska (the Alaskan 'panhandle').

Methods We quantified range marginality using spatial distributions of eight tree species across more than one thousand surveyed sites in Southeast Alaska. For each species we derived a site core/margin index using a three-dimensional trend surface generated from logistic regression on site coordinates. For each species, the relationships between the environmental factors slope, aspect and site marginality were then compared for occupied and unoccupied sets of sites.

Results We found that site slope is important for more Alaskan tree species than aspect. Three out of eight had a significant core/margin by occupied/unoccupied interaction, tending to be present in significantly shallower-sloped (more favourable) sites in the marginal areas than the simple core/margin trend predicted. For site aspect, one species had a significant interaction, selecting potentially more favourable northerly aspects in marginal areas. A finer-scale analysis based on the same data came to the same overall conclusions.

Conclusions There is evidence that several tree species in Alaska tend to occur in especially favourable sites in marginal areas. In these marginal areas, these species amplify habitat preferences shown in core areas.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Existing compact routing schemes, e.g., Thorup and Zwick [SPAA 2001] and Chechik [PODC 2013], often have no means to tolerate failures, once the system has been setup and started. This paper presents, to our knowledge, the first self-healing compact routing scheme. Besides, our schemes are developed for low memory nodes, i.e., nodes need only O(log2 n) memory, and are thus, compact schemes.
We introduce two algorithms of independent interest: The first is CompactFT, a novel compact version (using only O(log n) local memory) of the self-healing algorithm Forgiving Tree of Hayes et al. [PODC 2008]. The second algorithm (CompactFTZ) combines CompactFT with Thorup-Zwick’s treebased compact routing scheme [SPAA 2001] to produce a fully compact self-healing routing scheme. In the self-healing model, the adversary deletes nodes one at a time with the affected nodes self-healing locally by adding few edges. CompactFT recovers from each attack in only O(1) time and ∆ messages, with only +3 degree increase and O(log∆) graph diameter increase, over any sequence of deletions (∆ is the initial maximum degree).
Additionally, CompactFTZ guarantees delivery of a packet sent from sender s as long as the receiver has not been deleted, with only an additional O(y log ∆) latency, where y is the number of nodes that have been deleted on the path between s and t. If t has been deleted, s gets informed and the packet removed from the network.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

Two species of Osmundea Stackhouse (Rhodomelaceae, Rhodophyta) that occur in Atlantic Europe have been confused under the names Osmundea ramosissima (Oeder) Athanasiadis and Osmundea truncata (Kutzing) Nam et Maggs, regarded until now as a synonym of O. ramosissima, An epitype from its type locality (Stavanger, Norway) is selected for Osmundea ramosissima Athanasiadis, recognized here as a valid name for Fucus ramosissimus Oeder, nom. illeg. Details of vegetative and reproductive morphology of O. ramosissima are reported, based on material from France, the British Isles, and Helgoland. Osmundea ramosissima resembles other species of Osmundea in its vegetative axial segments with two pericentral cells and one trichoblast, spermatangial development from apical and epidermal cells (filament type), the formation of five pericentral cells in the procarp-bearing segment of the female trichoblast, and tetrasporangial production from random epidermal cells. Among the species of Osmundea, O. ramosissima is most similar to O. truncata. Both species have discoid holdfasts, secondary pit connections between epidermal cells, and cup-shaped spermatangial pits. They differ in that: (a) O. ramosissima lacks lenticular wail thickenings and refractive needle-like inclusions in medullary cells, both of which are present in O. truncata; (b) O. ramosissima has branched spermatangial filaments that terminate in a cluster of several cells, whereas in O. truncata the unbranched spermatangial filaments have a single large terminal sterile cell; and (c) cystocarps of O. ramosissima lack protuberant ostioles but ostioles are remarkably protuberant in o. truncata. Phylogenetic analyses of rbcL sequences of Laurencia obtusa (Hudson) Lamouroux and all five Atlantic European species of Osmundea, including the type species, strongly support the generic status of Osmundea. Osmundea ramosissima and O. truncata are closely related (5.2% sequence divergence) and form a well-supported clade sister to a clade consisting of O. pinnatifida (Hudson) Stack-house, O. osmunda Stackhouse and O. hybrida (A. P. de Candolle) Nam. The formation of secondary pit connections between epidermal cells is a synapomorphy for the O. ramosissima + O. truncata clade. The close relationship between species with cup-shaped spermatangial pits (Osmundea hybrida) and urn-shaped pits (Osmundea pinnatifida and Osmundea osmunda) shows that spermatangial pit shape is not an important phylogenetic character. Parsimony analysis of a morphological data set also supports the genus Osmundea but conflicts with the molecular trees in infrageneric relationships, placing O. hybrida basal within the Osmundea clade and grouping O. osmunda and O. pinnatifida but not O. truncata and O. ramosissima. A key to Osmundea species is presented.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

This paper will explore the development of increased group tensions in Northern Ireland
over the past decade with a special emphasis being placed upon rising racial tensions in cities such
as Belfast and Lisburn. The paper will analyse why Northern Ireland has been described as the new
race-hate capital of Europe and, through a case-study of Loyalism, will argue that if this growth in
racist sentiment is to be prevented, more needs to be done to understand the causes of such feeling,
particularly within loyalist working-class areas. I will argue that society as a whole needs to address
the fears and anxieties of those that perceive themselves to be under threat from the recent increase
in immigration or else we risk creating a new cause célèbre for those that would seek to extend the
lifetime of our paramilitary organisations. Moreover, at a time when loyalist communities feel politically
alienated and lacking representation, there is a real danger of British far-right groups exploiting the
situation and making long-term political capital.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

The chapter focuses on the development of sustainable growing infrastructure in the city at two scales. Firstly the development of a large-scale city wide fuel productive landscape through the development of algae arrays in Liverpool and their connection through urban agriculture systems to develop a closed-cycle food and energy system where waste is food and secondly a hyper-localised neighbourhood food production system in Salford UK that utilises a closed cycle aquaponic system to re-invigorate an urban food desert.

The author develops a three-part model for the implementation of urban agriculture based on hardware (the technological system), software (the biological components) and interface (the links to food and other social networks). The conclusion being that it is possible to develop urban agriculture in cities if their implementation is seen as a process, rather than a static design. Also that as the benefits of such systems are wider than purely the physical outputs of the system in terms of energy and food, and thus we should re-evaluate the purely economic model of appraisal to include these.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

In exploring the connections between religion, violence and cities, the book probes the extent to which religion moderates or exacerbates violence in an increasingly urbanised world. Originating in a five year research project , Conflict in Cities and the Contested State, concerned with Belfast, Jerusalem and other ethno-nationally divided cities, this volume widens the geographical focus to include diverse cities from the Balkans, the Middle East, Nigeria and Japan. In addressing the understudied triangular relationships between religion, violence and cities, contributors stress the multiple forms taken by religion and violence while challenging the compartmentalisation of two highly topical debates – links between religion and violence on the one hand, and the proliferation of violent urban conflicts on the other hand. Their research demonstrates why cities have become so important in conflicts driven by state-building, fundamentalism, religious nationalism, and ethno-religious division and illuminates the conditions under which urban environments can fuel violent conflicts while simultaneously providing opportunities for managing or transforming them.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

Issues of authenticity and identity are particularly significant in cities where social and cultural change is shaping active transformation of its urban fabric and structure in the post-war condition. In search of sustainable future, Iraqi cities are stretched between the two ends of the spectrum, authentic quarters with its traditional fabric and modern districts with their global sense of living. This paper interrogates the reciprocal influences, distinct qualities and sustainable performance of both authentic and modern quarters of Erbil, the
capital of the Iraqi province of Kurdistan, as factors in shaping sustainable urban forms for Iraqi cities. In doing so, the paper, firstly, seeks to highlight the urban identity as an effective factor in relation to sustainable urban form. Secondly, the city of Erbil in Iraq has been chosen as a field study, due to its regional, social, political and historical role in the region. Thirdly, the study emphasises the dynamic activities and performance of residential projects according to rational sustainable criteria. The research concludes that urban identity and the sense of place in traditional and historical places should inform design strategies in order to achieve a more sustainable urban context.