4 resultados para Landscape transition

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


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Eusociality is widely considered a major evolutionary transition. The socially polymorphic sweat bee Halictus rubicundus, solitary in cooler regions of its holarctic range and eusocial in warmer parts, is an excellent model organism to address this transition, and specifically the question of whether sociality is associated with a strong barrier to gene flow between phenotypically divergent populations. Mitochondrial DNA (COI) from specimens collected across the British Isles, where both solitary and social phenotypes are represented, displayed limited variation, but placed all specimens in the same European lineage; haplotype network analysis failed to differentiate solitary and social lineages. Microsatellite genetic variability was high and enabled us to quantify genetic differentiation among populations and social phenotypes across Great Britain and Ireland. Results from conceptually different analyses consistently showed greater genetic differentiation between geographically distant populations, independently of their social phenotype, suggesting that the two social forms are not reproductively isolated. A landscape genetic approach revealed significant isolation by distance (Mantel test r = 0.622, p

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The landscape of political imprisonment in Northern Ireland was changed due to the general release and reintegration of politically motivated prisoners as part of the Belfast Agreement. This article reflects upon the post-prison experiences of former prisoners and their families, and in particular how the move from a resistant to a transitional framework has facilitated a greater openness and willingness amongs ex-prisoners to acknowledge the personal and familial problems related to incarceration. We also explore the ways in which ex-prisoners have attempted to deal with the continued social, political and civic exclusion which arises as a result of their conflict-related 'criminal' convictions. In the final section of the article, the authors further develop the move from a resistant to a transitional characterization of incarceration and its consequences.

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Northern Ireland is in the early stages of transition from conflict, but progress is regularly affected by political and public discontent. A divided landscape, segregated and under-resourced communities are enduring legacies of ‘the Conflict’. Yet the political will to tackle social and community division, consult with and support communities has been lacking. Grounded in six communities most affected by poverty and the Conflict this paper illustrates the difficulties, tensions and contradictions experienced during transition and how, in the process of ‘change’, children and young people have been silenced, marginalised and
demonised.

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The current model of mid-latitude late Quaternary terrace sequences, is that they are uplift-driven but climatically controlled terrace staircases, relating to both regional-scale crustal and tectonic factors, and palaeohydrological variations forced by quasi-cyclic climatic conditions in the 100 K world (post Mid Pleistocene Transition). This model appears to hold for the majority of the river valleys draining into the English Channel which exhibit 8–15 terrace levels over approximately 60–100 m of altitudinal elevation. However, one valley, the Axe, has only one major morphological terrace and has long-been regarded as anomalous. This paper uses both conventional and novel stratigraphical methods (digital granulometry and terrestrial laser scanning) to show that this terrace is a stacked sedimentary sequence of 20–30 m thickness with a quasi-continuous (i.e. with hiatuses) pulsed, record of fluvial and periglacial sedimentation over at least the last 300–400 K yrs as determined principally by OSL dating of the upper two thirds of the sequence. Since uplift has been regional, there is no evidence of anomalous neotectonics, and climatic history must be comparable to the adjacent catchments (both of which have staircase sequences) a catchment-specific mechanism is required. The Axe is the only valley in North West Europe incised entirely into the near-horizontally bedded chert (crypto-crystalline quartz) and sand-rich Lower Cretaceous rocks creating a buried valley. Mapping of the valley slopes has identified many large landslide scars associated with past and present springs. It is proposed that these are thaw-slump scars and represent large hill-slope failures caused by Vauclausian water pressures and hydraulic fracturing of the chert during rapid permafrost melting. A simple 1D model of this thermokarstic process is used to explore this mechanism, and it is proposed that the resultant anomalously high input of chert and sand into the valley during terminations caused pulsed aggradation until the last termination. It is also proposed that interglacial and interstadial incision may have been prevented by the over-sized and interlocking nature of the sub-angular chert clasts until the Lateglacial when confinement of the river overcame this immobility threshold. One result of this hydrogeologically mediated valley evolution was to provide a sequence of proximal Palaeolithic archaeology over two MIS cycles. This study demonstrates that uplift tectonics and climate alone do not fully determine Quaternary valley evolution and that lithological and hydrogeological conditions are a fundamental cause of variation in terrestrial Quaternary records and landform evolution.