903 research outputs found
Implication of two new paradigms for futures studies
The paper considers the emergence of two recent perspectives in futures work. One is evolutionary futures studies. The other is critical futures studies. After describing aspects of
each, the paper considers them as alternative rival paradigms in relation to criteria that include: the role of the human being as a subject, the role of interpretation and differences in methodological premises. It concludes that both have contributed to the development of futures methods but that a number of theoretical and methodological problems still remain unsolved
Theory and practice in the field of foresight
Purpose – The paper aims to explore the gap between theory and practice in foresight and to give some suggestions on how to reduce it.
Design/methodology/approach – Analysis of practical foresight activities and suggestions are based on a literature review, the author's own research and practice in the field of foresight and futures studies, and her participation in the work of a European project (COST A22).
Findings – Two different types of practical foresight activities have developed. One of them, the practice of foresight of critical futures studies (FCFS) is an application of a theory of futures studies. The other, termed here as praxis foresight (PF), has no theoretical basis and responds directly to practical needs. At present a gap can be perceived between theory and practice. PF distinguishes itself from the practice and theory of FCFS and narrows the construction space of futures. Neither FCFS nor PF deals with content issues of the outer world. Reducing the gap depends on renewal of joint discourses and research about experience of different practical foresight activities and manageability of complex dynamics in foresight. Production and feedback of self-reflective and reflective foresight knowledge could improve theory and practice.
Originality/value – Contemporary practical foresight activities are analysed and suggestions to reduce the gap are developed in the context of the linkage between theory and practice. This paper is thought provoking for futurists, foresight managers and university researchers
Developmental stage is an important factor that determines the antioxidant responses of young and old grapevine leaves under UV irradiation in a green-house.
The impact of UV irradiation was studied on photosynthesis, photosystem II photochemical
yields and antioxidant responses using green-house grown grapevine (Vitis vinifera L. cv. Chardonnay)
leaves. Supplemental UV irradiation (290-400 nm) was centred in the UV-B region, and corresponded
to 8.95 kJ m-2 d-1 global (280-400 nm) or 8.04 kJ m-2 d-1 UV-B (280-315 nm) biologically effective
dose. UV irradiation was applied daily and its effects were evaluated after 4-days. Younger (1-3 weeksold)
leaves (YL) and older (4-6 weeks-old) leaves (OL) were affected differently, UV irradiation
decreased their photochemical yields to 78% and 56%, respectively. Unlike OL, YL responded by an
increase in UV-B absorbing pigment, anthocyanin and total phenolics contents. UV irradiation
increased total antioxidant capacities in YL but not in OL. YL were also different in their ability to
increase speciıic hydroxyl radical and singlet oxygen neutralizing capacities in response to the
supplemental UV irradiation, which is reported here for the ıirst time. Our results suggest that the
ability of maintaining photosynthesis under supplemental UV is not necessarily determined by base
levels of antioxidants but rather by their inducibilities in response to the irradiation and emphasise the
importance of comparing leaves of the same age in UV studies. Correlations between various
antioxidant capacities, pigment contents and photosynthesis parameters were also examined.
However, no single element of the defence system can be picked up as decisive factor of sensitivity to
UV
Existing antioxidant levels are more important in acclimation to supplemental UV-B irradiation than inducible ones: Studies with high light pretreated tobacco leaves
Greenhouse grown tobacco plants were exposed to supplemental ultraviolet irradiation (280-400 nm, UV-B
centered) for 6 days and changes in their photosynthesis (gas exchange and electron transport) and general and
specific antioxidant activities were measured. UV irradiation corresponded to 8.95 kJ m-2 d-1 biologically
effective dose and was supplemented to below ambient (200 μmol m-2 s-1 photon flux density) photosynthetic
photon flux density (PPFD, 400-700 nm). Two groups of plants, which were different in their leaf antioxidant
capacities due to one of them having been acclimated to high irradiance (1000 μmol m-2 s-1 PPFD) before the
UV treatment, responded differently. High light pretreated leaves lost approximately 25% of photosynthetic
activity during the UV exposure and showed no change either in the amounts of UV-absorbing pigments or
antioxidant levels. On the other hand, leaves which were exposed to UV irradiation without the preceding high
light acclimation had 60% lower photosynthesis by the end of the treatment, and increased antioxidant
activities. Our results emphasize the importance of base antioxidant levels over inducible pools in leaf responses
to low doses of UV irradiation and may also contribute to hypotheses on acclimation under field conditions
Developmental stage is an important factor that determines the antioxidant responses of young and old grapevine leaves under UV irradiation in a green-house.
The impact of UV irradiation was studied on photosynthesis, photosystem II photochemical
yields and antioxidant responses using green-house grown grapevine (Vitis vinifera L. cv. Chardonnay)
leaves. Supplemental UV irradiation (290-400 nm) was centred in the UV-B region, and corresponded
to 8.95 kJ m-2 d-1 global (280-400 nm) or 8.04 kJ m-2 d-1 UV-B (280-315 nm) biologically effective
dose. UV irradiation was applied daily and its effects were evaluated after 4-days. Younger (1-3 weeksold)
leaves (YL) and older (4-6 weeks-old) leaves (OL) were affected differently, UV irradiation
decreased their photochemical yields to 78% and 56%, respectively. Unlike OL, YL responded by an
increase in UV-B absorbing pigment, anthocyanin and total phenolics contents. UV irradiation
increased total antioxidant capacities in YL but not in OL. YL were also different in their ability to
increase speciıic hydroxyl radical and singlet oxygen neutralizing capacities in response to the
supplemental UV irradiation, which is reported here for the ıirst time. Our results suggest that the
ability of maintaining photosynthesis under supplemental UV is not necessarily determined by base
levels of antioxidants but rather by their inducibilities in response to the irradiation and emphasise the
importance of comparing leaves of the same age in UV studies. Correlations between various
antioxidant capacities, pigment contents and photosynthesis parameters were also examined.
However, no single element of the defence system can be picked up as decisive factor of sensitivity to
UV
Synthesis and potential use of 1,8-naphthalimide type O-1(2) sensor molecules
New double (fluorescent and spin) sensor molecules containing 4-amino substituted 1,8-naphthalimide as a fluorophore and a sterically hindered amine (pre-nitroxide) or pyrroline nitroxide as a quencher and radical capturing moiety were synthesized. All sensors were substituted with a diethylaminoethyl side-chain to increase the water solubility. Steady state fluorescence properties of these compounds and their responses to ROS in vitro are reported with perspectives of plant physiology use in vivo
UV-B exposure, ROS, and stress: inseparable companions or loosely linked associates?
Ultraviolet-B (UV-B) radiation has long been perceived as a stressor. However, a conceptual U-turn has taken place, and UV-B damage is now considered rare. We question whether UV-stress and UV-B-induced reactive oxygen species (ROS) are still relevant concepts, and if ROS-mediated signaling contributes to UV-B acclimation. Measurements of antioxidants and of antioxidant genes show that both low and high UV-B doses alter ROS metabolism. Yet, there is no evidence that ROS control gene expression under low UV-B. Instead, expression of antioxidant genes is linked to the UV RESISTANCE LOCUS 8 pathway. We hypothesize that low UVB doses cause ‘eustress’ (good stress) and that stimulispecific signaling pathways pre-dispose plants to a state of low alert that includes activation of antioxidant defenses.Funding agencies are:COST Action FA0906UV4Growth Faculty of Business, Science, and Technology at Örebro University Science Foundation Ireland (SFI) 11/RFP.1/EOB/3303 Hungarian Scientific Research Fund OTKA NN-85349 UV-B-fotobiologi: mekanismer för perception och cellulära response
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