Search results for "ferns"

Towards a Critical Flora of Italy: Assessing the Lycopodiophyta

2013

Effects of temperature and desiccation on ex situ conservation of nongreen fern spores

2012

Premise of the study Fern spores are unicellular and haploid, making them a potential model system to study factors that regulate lifespan and mechanisms of aging. Aging rates of nongreen spores were measured to compare longevity characteristics among diverse fern species and test for orthodox response to storage temperature and moisture. Methods Aging of spores from 10 fern species was quantified by changes in germination and growth parameters. Storage temperature ranged from ambient room to -196°C (liquid nitrogen); spores were dried to ambient relative humidity (RH) or using silica gel. Key results Survival of spores varied under ambient storage conditions, with one species dying within …

Water properties in fern spores: sorption characteristics relating to water affinity, glassy states, and storage stability.

2007

Ex situ conservation of ferns may be accomplished by maintaining the viability of stored spores for many years. Storage conditions that maximize spore longevity can be inferred from an understanding of the behaviour of water within fern spores. Water sorption properties were measured in spores of five homosporeous species of ferns and compared with properties of pollen, seeds, and fern leaf tissue. Isotherms were constructed at 5, 25, and 45 degrees C and analysed using different physicochemical models in order to quantify chemical affinity and heat (enthalpy) of sorption of water in fern spores. Fern spores hydrate slowly but dry rapidly at ambient relative humidity. Low Brunauer-Emmet-Tel…

Calorimetric properties of water and triacylglycerols in fern spores relating to storage at cryogenic temperatures.

2007

Abstract Storing spores is a promising method to conserve genetic diversity of ferns ex situ . Inappropriate water contents or damaging effects of triacylglycerol (TAG) crystallization may cause initial damage and deterioration with time in spores placed at −15 °C or liquid nitrogen temperatures. We used differential scanning calorimetry (DSC) to monitor enthalpy and temperature of water and TAG phase transitions within spores of five fern species: Pteris vittata , Thelypteris palustris , Dryopteris filix-mas , Polystichum aculeatum , Polystichum setiferum . The analyses suggested that these fern spores contained between 26% and 39% TAG, and were comprised of mostly oleic ( P. vittata ) or …

Ievads vispārējā bioloģijā

1926

No angļu valodas tulkojis Egons Dārziņš

Mehr als Musik: Die sieben Dimensionen des Eurovision Song Contests

2008

"Der Eurovision Song Contest (ESC) ist der weltweit größte internationale Wettbewerb für populäre Musik und das erfolgreichste Fernsehunterhaltungsprogramm in Europa. Obwohl der ESC ursprünglich das Ziel verfolgte, die Entstehung neuer Lieder zu fördern, handelte es sich doch stets um ein von den Fernsehanstalten inszeniertes Medienereignis, das erst nachrangig musikökonomischen Zwecken dient. Für das Publikum ist der ESC auf Grund seiner Periodizität, seiner spezifischen Programmstruktur und nicht zuletzt des Zugehörigkeitsgefühls der Zuschauer, das auf Schemata nationaler und kultureller Identifikation beruht, zu einem hochgradig ritualisierten Medienereignis geworden. Seine Bedeutung geh…