title: Photosynthetic performance of Xanthoria mawsonii C. W. Dodge in coastal habitats, Ross Sea region, continental Antarctica

authors: Pannewitz, Stefan

subjects: chlorophyll a fluorescence

abstract: Xanthoria mawsonii C. W. Dodge was found to perform well physiologically in a variety of habitats at high latitudes in continental Antarctica. The net photosynthetic rate of 7•5 μ mol CO2 kg−1 s−1 is exceptionally high for Antarctic lichens. Field and laboratory measurements proved the photosynthetic apparatus to be highly adapted to strong irradiance. The cold resistance of the photosystem II reaction centres is higher than the photosynthetic CO2 fixation process. Optimum temperature for net photosynthesis was c. 10°C. The lichen grows along water channels where it is frequently inundated and hydrated to maximum water content, although net photosynthesis is strongly depressed by super saturation. In these habitats the lichen is photosynthetically active for long periods of time. Xanthoria mawsonii also grows at sites where it depends entirely on the early spring snow melt and occasional snow fall for moisture. It has an exceptionally short reactivation phase and is able to utilize snow immediately. Recovery of activity by absorbing water vapour from air, though practically possible, seems to be of ecological importance only under snow at subzero temperatures.

text: Photosynthetic performance of Xanthoria mawsonii C. W. Dodge in coastal habitats, Ross Sea region, continental Antarctica Xanthoria mawsonii C. W. Dodge was found to perform well physiologically in a variety of habitats at high latitudes in continental Antarctica. The net photosynthetic rate of 7•5 μ mol CO2 kg−1 s−1 is exceptionally high for Antarctic lichens. Field and laboratory measurements proved the photosynthetic apparatus to be highly adapted to strong irradiance. The cold resistance of the photosystem II reaction centres is higher than the photosynthetic CO2 fixation process. Optimum temperature for net photosynthesis was c. 10°C. The lichen grows along water channels where it is frequently inundated and hydrated to maximum water content, although net photosynthesis is strongly depressed by super saturation. In these habitats the lichen is photosynthetically active for long periods of time. Xanthoria mawsonii also grows at sites where it depends entirely on the early spring snow melt and occasional snow fall for moisture. It has an exceptionally short reactivation phase and is able to utilize snow immediately. Recovery of activity by absorbing water vapour from air, though practically possible, seems to be of ecological importance only under snow at subzero temperatures.

year: 2006

title: Subject metadata support powered by Maui

authors: Medelyan, Olena

subjects: metadata extraction

abstract: Selecting subject headings and keywords is a chore for all metadata editors, who often leave these fields blank or incomplete—even when there are no guidelines and any word or phrase can be chosen. For example, tags are absent from the vast majority of citations in the social scholarly reference repository CiteULike. Libraries employ professional cataloguers and indexers to ensure consistent subject metadata in their records. Because this task is time-consuming, professionals and volunteers alike would welcome high-quality automatically generated suggestions for the main topics of a document.

text: Subject metadata support powered by Maui Selecting subject headings and keywords is a chore for all metadata editors, who often leave these fields blank or incomplete—even when there are no guidelines and any word or phrase can be chosen. For example, tags are absent from the vast majority of citations in the social scholarly reference repository CiteULike. Libraries employ professional cataloguers and indexers to ensure consistent subject metadata in their records. Because this task is time-consuming, professionals and volunteers alike would welcome high-quality automatically generated suggestions for the main topics of a document.

year: 2010

title: Tūturu whakamaua ko te kupu, haumi e, hui e, ko ngā kupu o te mātauranga ē!

authors: Dale, Hēmi

subjects: Reo Māori

abstract: Ko tā tēnei tuhinga he arotahi ki ētahi o ngā take reo e pā ana ki ngā mahi whakangungu pouako mā te huarahi o te reo Māori i roto i te whare wānanga. Ka mutu, ka kōrerorerotia ngā urupare a te Huarahi Māori (tētahi kaiwhakarato whakangungu pouako mā te huarahi o te reo Māori) ki ētahi o ēnei take reo.

text: Tūturu whakamaua ko te kupu, haumi e, hui e, ko ngā kupu o te mātauranga ē! Ko tā tēnei tuhinga he arotahi ki ētahi o ngā take reo e pā ana ki ngā mahi whakangungu pouako mā te huarahi o te reo Māori i roto i te whare wānanga. Ka mutu, ka kōrerorerotia ngā urupare a te Huarahi Māori (tētahi kaiwhakarato whakangungu pouako mā te huarahi o te reo Māori) ki ētahi o ēnei take reo.

year: 2017