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Sustained Engagement (sustained + engagement)

Distribution by Scientific Domains

Life Sciences	50%
Humanities and Social Sciences	50%

Selected Abstracts

Photosynthesis and Photoprotection in Overwintering Plants

PLANT BIOLOGY, Issue 5 2002
W. W. Adams III
Abstract: Seasonal differences in the capacity of photosynthetic electron transport, leaf pigment composition, xanthophyll cycle characteristics and chlorophyll fluorescence emission were investigated in two biennial mesophytes (Malva neglecta and Verbascum thapsus) that grow in full sunlight, and in leaves/needles of sun and shade populations of several broad-leafed evergreens and conifers (Vinca minor, Euonymus kiautschovicus, Mahonia repens, Pseudotsuga menziesii [Douglas fir], and Pinus ponderosa). Both mesophytic species maintained or upregulated photosynthetic capacity in the winter and exhibited no upregulation of photoprotection. In contrast, photosynthetic capacity was downregulated in sun leaves/needles of V. minor, Douglas fir, and Ponderosa pine, and even in shade needles of Douglas fir. Interestingly, photosynthetic capacity was upregulated during the winter in shade leaves/needles of V. minor, Ponderosa pine and Euonymus kiautschovicus. Nocturnal retention of zeaxanthin and antheraxanthin, and their sustained engagement in a state primed for energy dissipation, were observed largely in the leaves/needles of sun-exposed evergreen species during winter. Factors that may contribute to these differing responses to winter stress, including chloroplast redox state, the relative levels of source and sink activity at the whole plant level, and apoplastic versus symplastic phloem loading, are discussed. [source]

Nocturnally retained zeaxanthin does not remain engaged in a state primed for energy dissipation during the summer in two Yucca species growing in the Mojave Desert

PLANT CELL & ENVIRONMENT, Issue 1 2002
D. H. Barker
Abstract Differently oriented leaves of Yucca schidigera and Yucca brevifolia were characterized in the Mojave Desert with respect to photosystem II and xanthophyll cycle activity during three different seasons, including the hot and dry summer, the relatively cold winter, and the mild spring season. Photosynthetic utilization of a high percentage of the light absorbed in PSII was observed in all leaves only during the spring, whereas very high levels of photoprotective, thermal energy dissipation were employed both in the summer and the winter season in all exposed leaves of both species. Both during the summer and the winter season, when energy dissipation levels were high diurnally, xanthophyll cycle pools (relative to either Chl or other carotenoids) were higher relative to the spring, and a nocturnal retention of high levels of zeaxanthin and antheraxanthin (Z + A) occurred in all exposed leaves of both species. Although this nocturnal retention of Z + A was associated with nocturnal maintenance of a low PSII efficiency (Fv/Fm) on a cold winter night, pre-dawn Fv/Fm was high in (Z + A)-retaining leaves following a warm summer night. This indicates nocturnal engagement of Z + A in a state primed for energy dissipation throughout the cold winter night , while high levels of retained Z + A were not engaged for energy dissipation prior to sunrise on a warm summer morning. Possible mechanisms for a lack of sustained engagement of retained Z + A for energy dissipation at elevated temperatures are discussed. [source]

ACKNOWLEDGING A HIDDEN GOD: A THEOLOGICAL CRITIQUE OF STANLEY CAVELL ON SCEPTICISM

THE HEYTHROP JOURNAL, Issue 3 2007
JUDITH E. TONNING
In his early work, the philosopher Stanley Cavell offers a sustained engagement with the threat of epistemological scepticism, shaped by the intuition that although (as the late Wittgenstein shows) ordinary language use is the practice within which alone meaning is possible (and which can thus not be further analysed or rationalised), it is also a basic human inclination to wish to escape the limitations of the ,ordinary'. This, for Cavell, is the root of scepticism. Scepticism, on this view, thus appears not primarily as an epistemological but as an (injurious) moral stance, which cannot be refuted but must be continually confronted and overcome. Vis-à-vis scepticism, ,acknowledgement' is the practice-based recognition of the world and other people in their continuing elusiveness, which ineluctably involves risk, but just so is the only way of knowing that is appropriate to and honours the (finite) human condition. One problematic aspect of this (very fertile) approach is that Cavell's secular viewpoint makes it difficult for him to say both why the desire for a ,beyond' arises in the first place, and why its expression as denial is morally wrong (rather than merely misguided). His approach thus invites a theological ,supplementation' which grounds the human condition in an original and real relation to God that is meant to draw the believer, through Christ, into the divine life itself. Such a reinterpretation both elucidates the concepts of scepticism and acknowledgement, and makes these concepts available for a theological outlook that is able to accommodate Cavell's profound insights into ,the human'. [source]

Ethnography, space and politics: interrogating the process of protest in the Tibetan Freedom Movement

AREA, Issue 1 2009
Andrew D Davies
This paper examines the ability of ethnographic research methods to effectively study spatially extensive political activity. It argues that traditional ethnographic methods of sustained engagement with spatially bounded sites are not adequately suited to dealing with contemporary spatially extensive political movements. It argues that contemporary attempts to bridge this impasse have emphasised a dichotomy between global and local that ignores the connections, disconnections and process that occur between places. The paper argues for a critical ethnography that is based on a relational understanding of space emphasising Gillian Hart's conception of the interconnected nature of the ,site'. Taking a single demonstration against the Beijing 2008 Olympics conducted by UK-based Tibet supporters, it examines how the site of protest was closely linked to a variety of other places. Interrogating the processes of connection and disconnection brought about through the protest creates an ethnographic account that, while partial, develops an engagement with the heterogeneity of contemporary political action. [source]