Search results for "Sphere"
showing 10 items of 2121 documents
Contribution of Excited Ozone and Oxygen Molecules to the Formation of the Stratospheric Ozone Layer
2019
The absorption of UV, visible and near IR radiation by O3 produces transient, electronically excited O3. The absorption of thermal IR radiation ( = 9.065, 9.596 and 14.267 µm) produces vibrationally excited O3 molecules. Thermal absorption is likely the main factor in the self-decay of O3. Photoexcitation of ground state by IR and red light radiation produces singlet oxygens and . Chemical reactions in the stratosphere produce them as well. When reacting with ozone, singlet oxygen produces O (3P) and . By doing so, they tend to maintain the prevailing ozone concentration and are thereby important for the stability of the ozone layer. During the daytime, O(1D), and reach their maximum concen…
Fluorescent pseudomonads harboring type III secretion genes are enriched in the mycorrhizosphere of Medicago truncatula
2011
Type III secretion systems (T3SSs) of Gram-negative bacteria mediate direct interactions with eukaryotic cells. Pseudomonas spp. harboring T3SS genes (T3SS+) were previously shown to be more abundant in the rhizosphere than in bulk soil. To discriminate the contribution of roots and associated arbuscular mycorrhizal fungi (AMF) on the enrichment of T3SS+ fluorescent pseudomonads in the rhizosphere of Medicago truncatula, their frequency was assessed among pseudomonads isolated from mycorrhizal and nonmycorrhizal roots and from bulk soil. T3SS genes were identified by PCR targeting a conserved hrcRST DNA fragment. Polymorphism of hrcRST in T3SS+ isolates was assessed by PCR-restriction fragm…
Chapter 4 Iron Dynamics in the Rhizosphere
2008
Abstract Iron is an essential micronutrient for most organisms due to its role in fundamental metabolic processes. In cultivated soils, soil solution iron is mostly oxidized [Fe(III) species] unless local anoxic conditions develop. The concentration of these Fe(III) species is small in soil solution due to the low solubility of ferric oxides, oxyhydroxides, and hydroxides, which is minimal at neutral and alkaline pH. In the rhizosphere, iron concentration in the soil solution is even lower because of its uptake by aerobic organisms (plants and microorganisms), leading to a high level of competition for Fe(III). In order to face iron competition, these organisms have evolved active uptake st…
Diversity of root-associated fluorescent pseudomonads as affected by ferritin overexpression in tobacco
2007
A transgenic tobacco overexpressing ferritin (P6) was recently shown to accumulate more iron than the wild type (WT), leading to a reduced availability of iron in the rhizosphere and shifts in the pseudomonad community. The impact of the transgenic line on the community of fluorescent pseudomonads was assessed. The diversity of 635 isolates from rhizosphere soils, rhizoplane + root tissues, and root tissues of WT and P6, and that of 98 isolates from uncultivated soil was characterized. Their ability to grow under iron stress conditions was assessed by identifying their minimal inhibitory concentrations of 8-hydroxyquinoline for each isolate, pyoverdine diversity by isoelectrofocusing and ge…
atzgene expressions during atrazine degradation in the soil drilosphere
2010
One of the various ecosystemic services sustained by soil is pollutant degradation mediated by adapted soil bacteria. The pathways of atrazine biodegradation have been elucidated but in situ expression of the genes involved in atrazine degradation has yet to be demonstrated in soil. Expression of the atzA and atzD genes involved in atrazine dechlorination and s-triazine ring cleavage, respectively, was investigated during in situ degradation of atrazine in the soil drilosphere and bulked samples from two agricultural soils that differed in their ability to mineralize atrazine. Interestingly, expression of the atzA gene, although present in both soils, was not detected. Atrazine mineralizati…
Heating glaciers from below
2013
Climate change is affecting the cryosphere from above. Geothermal heat flux from below is also contributing to conditions at the base of Greenland's ice sheet, which sits atop a lithosphere of variable thickness.
Narratives of Burnout and Recovery from an Agency Perspective : A Two-Year Longitudinal Study
2017
Abstract Purpose To provide knowledge about the recovery process during rehabilitation and two years later by exploring the manifestation of agency and spheres of meaning in the narratives of participants in a national rehabilitation course. Material and methods The subjects of the study were four participants in a national rehabilitation course, whose burnout levels had decreased between the initial and follow-up periods of the course. Semi-structured interviews on two occasions and an electronic questionnaire 1.5 years post rehabilitation comprised the main material. In addition, the BBI -15 (Bergen Burnout Indicator) and DEPS-screen were used. Results Thematic narrative analysis revealed…
Modeling of biomass smoke injection into the lower stratosphere by a large forest fire (Part II): Sensitivity studies
2006
Abstract. The Chisholm forest fire that burned in Alberta, Canada, in May 2001 resulted in injection of substantial amounts of smoke into the lower stratosphere. We used the cloud-resolving plume model ATHAM (Active Tracer High resolution Atmospheric Model) to investigate the importance of different contributing factors to the severe intensification of the convection induced by the Chisholm fire and the subsequent injection of biomass smoke into the lower stratosphere. The simulations show strong sensitivity of the pyro-convection to background meteorology. This explains the observed coincidence of the convective blow-up of the fire plume and the passage of a synoptic cold front. Furthermor…
A reactive nitrogen budget for forest land and wetlands in Latvia and Estonia
2020
Human intervention in global nitrogen cycling has led to excess reactive nitrogen (Nr) flows to the environment, impacting terrestrial ecosystems as well as the quality of the atmosphere and waterb...
Invisibilization and Silencing as an Ethical and Sociological Challenge
2017
AbstractExcluded and/or marginalized social groups frequently face problems involving representation in the public sphere. Moreover, the very notion of exclusion typically refers to communicatively or discursively produced mechanisms of being considered irrelevant in public processes of communication. Exclusion and marginalization, understood as processes of silencing or invisibilizing social groups, are particularly serious in cases involving social suffering, i.e. socially produced suffering and/or suffering that can be eliminated or alleviated socially. Making silence heard, giving voice to the silenced and bringing the invisibilized back into the public domain are therefore fundamental …