269 research outputs found

    Crustal fault reactivation facilitating lithospheric folding/buckling in the central Indian Ocean

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    High-quality, normal-incidence seismic reflection data confirm that tectonic deformation in the central Indian Ocean occurs at two spatial scales: whole lithosphere folding with wavelengths varying between 100 and 300 km, and compressional reactivation of crustal faults with a characteristic spacing of c. 5 km. Faults penetrate through the crust and probably into the upper mantle. Both types of deformation are driven by regional large intraplate stresses originating from the Indo-Eurasian collision. Numerical modelling of the spatial and temporal relationships between these two modes of deformations shows that, in agreement with geophysical observations, crustal faults are reactivated first with stick-slip behaviour. Subsequent lithospheric folding does not start until horizontal loading has significantly reduced the mechanical strength of the lithosphere, as predicted by elasto-plastic buckling theory. Modelling suggests that lithospheric folding does not develop in the absence of fault reactivation. Crustal fault reactivation, therefore, appears to be a key facilitating mechanism for oceanic lithospheric buckling in the central Indian Ocean

    The Sacred Geography of an Indonesian Islamic Modernity

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    In the centre of Tebu Ireng, Indonesia's most famous Islamic boarding school, is a mosque-graveyard complex which includes the grave of Hashim Ashari, the founder of Tebu Ireng who is remembered and revered as both a Sufi master and an Indonesian national hero. Around this physical and spiritual centre, a number of new spaces (schools, a telecommunications office, computer labs, and banks) have emerged. It is argued here that the very landscape of Tebu Ireng spatializes the kinds of relationships that the school's leaders argue that Muslims should have with the State, secular science, and the global market place

    Sequential bottlenecks drive viral evolution in early acute Hepatitis C virus infection

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    Hepatitis C is a pandemic human RNA virus, which commonly causes chronic infection and liver disease. The characterization of viral populations that successfully initiate infection, and also those that drive progression to chronicity is instrumental for understanding pathogenesis and vaccine design. A comprehensive and longitudinal analysis of the viral population was conducted in four subjects followed from very early acute infection to resolution of disease outcome. By means of next generation sequencing (NGS) and standard cloning/Sanger sequencing, genetic diversity and viral variants were quantified over the course of the infection at frequencies as low as 0.1%. Phylogenetic analysis of reassembled viral variants revealed acute infection was dominated by two sequential bottleneck events, irrespective of subsequent chronicity or clearance. The first bottleneck was associated with transmission, with one to two viral variants successfully establishing infection. The second occurred approximately 100 days post-infection, and was characterized by a decline in viral diversity. In the two subjects who developed chronic infection, this second bottleneck was followed by the emergence of a new viral population, which evolved from the founder variants via a selective sweep with fixation in a small number of mutated sites. The diversity at sites with non-synonymous mutation was higher in predicted cytotoxic T cell epitopes, suggesting immune-driven evolution. These results provide the first detailed analysis of early within-host evolution of HCV, indicating strong selective forces limit viral evolution in the acute phase of infection

    Lichenometric dating (lichenometry) and the biology of the lichen genus rhizocarpon:challenges and future directions

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    Lichenometric dating (lichenometry) involves the use of lichen measurements to estimate the age of exposure of various substrata. Because of low radial growth rates and considerable longevity, species of the crustose lichen genus Rhizocarpon have been the most useful in lichenometry. The primary assumption of lichenometry is that colonization, growth and mortality of Rhizocarpon are similar on surfaces of known and unknown age so that the largest thalli present on the respective faces are of comparable age. This review describes the current state of knowledge regarding the biology of Rhizocarpon and considers two main questions: (1) to what extent does existing knowledge support this assumption; and (2) what further biological observations would be useful both to test its validity and to improve the accuracy of lichenometric dates? A review of the Rhizocarpon literature identified gaps in knowledge regarding early development, the growth rate/size curve, mortality, regeneration, competitive effects, colonization, and succession on rock surfaces. The data suggest that these processes may not be comparable on different rock surfaces, especially in regions where growth rates and thallus turnover are high. In addition, several variables could differ between rock surfaces and influence maximum thallus size, including rate and timing of colonization, radial growth rates, environmental differences, thallus fusion, allelopathy, thallus mortality, colonization and competition. Comparative measurements of these variables on surfaces of known and unknown age may help to determine whether the basic assumptions of lichenometry are valid. Ultimately, it may be possible to take these differences into account when interpreting estimated dates

    Can You Hear us Now? Voices from the Margin: Using Indigenous Methodologies in Geographic Research

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    Indigenous methodologies are an alternative way of thinking about research processes. Although these methodologies vary according to the ways in which different Indigenous communities express their own unique knowledge systems, they do have common traits. This article argues that research on Indigenous issues should be carried out in a manner which is respectful and ethically sound from an Indigenous perspective. This naturally challenges Western research paradigms, yet it also affords opportunities to contribute to the body of knowledge about Indigenous peoples. It is further argued that providing a mechanism for Indigenous peoples to participate in and direct these research agendas ensures that their communal needs are met, and that geographers then learn how to build ethical research relationships with them. Indigenous methodologies do not privilege Indigenous researchers because of their Indigeneity, since there are many ‘insider’ views, and these are thus suitable for both Indigenous and non-Indigenous researchers. However, there is a difference between research done within an Indigenous context using Western methodologies and research done using Indig- enous methodologies which integrates Indigenous voices. This paper will discuss those differences while presenting a historical context of research on Indigenous peoples, providing further insights into what Indigenous methodologies entail, and proposing ways in which the academy can create space for this discourse

    Personal goals, group performance and ‘social’ networks: participants’ negotiation of virtual and embodied relationships in the ‘Workplace Challenge’ physical activity programme

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    County Sports Partnerships (CSPs) epitomise the growing reliance upon building networks and partnerships sports delivery. This study investigated how social networks were created and contested in a CSP-led programme entitled the ‘Workplace Challenge’ (WPC). The WPC used a web-platform to encourage workplace-based teams to engage in physical activity by self-recording their activity over an eight-week period. Points were awarded for activity completed and a peer-challenge facility was promoted via online league tables, prizes and the opportunity to ‘challenge’ other users. Semi-structured interviews were conducted with a total of seventeen participants recruited from one public and one private sector workplace and from a sample of participants registered as individuals. Two programme planners employed by the CSP also took part. A figurational framework was utilised to investigate participants’ negotiation of networks of embodied and virtual relationships within the programme. Findings suggest the messages promoted in the WPC were disseminated and transformed according to the organizational structure of these networks. Embodied social relationships within workplaces reinforced peer support in professional I-we identities, whereas virtual networks sometimes highlighted participants’ isolation. Moreover, emphasis upon competition within and between teams caused some to question their performance. Often, competition motivated engagement. For less active participants, constant comparison could prove discouraging, particularly if participants felt they had let their colleagues down. Planners of similar programmes must be cognizant of the uneven manner of programme dissemination. Contextual differences at the point of delivery including existing organizational structures and power hierarchies have an impact upon participants’ perceptions of a programme

    New results from the NA57 experiment

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    We report results from the experiment NA57 at CERN SPS on hyperon production at midrapidity in Pb-Pb collisions at 158 AA GeV/cc and 40 AA GeV/cc. Λ\Lambda, Ξ\Xi and Ω\Omega yields are compared with those from the STAR experiment at the higher energy of the BNL RHIC. Λ\Lambda, Ξ\Xi, Ω\Omega\ and preliminary KS0K_S^0 transverse mass spectra are presented and interpreted within the framework of a hydro-dynamical blast wave model.Comment: 8 pages, 3 figures, contribution to the proceedings of The XXXVIIIth Rencontres de Moriond "QCD and High Energy Hadronic Interactions

    Expansion dynamics of Pb-Pb collisions at 40 A GeV/c viewed by negatively charged hadrons

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    In this paper we present results on transverse mass spectra and Hanbury-Brown and Twiss correlation functions of negatively charged hadrons, which are expected to be mostly negative pions, measured in Pb-Pb collisions at 40 A GeV/c beam momentum. Based on these data, the collision dynamics and the space-time extent of the system at the thermal freeze-out are studied over a centrality range corresponding to the most central 53% of the Pb--Pb inelastic cross section. Comparisons with freeze-out conditions of strange particles and HBT results from other experiments are discussed.Comment: 29 pages, 18 figure
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