Search results for "ddc:5"
showing 10 items of 1717 documents
Nucleus-driven crystallization of amorphous Ge2Sb2Te5: A density functional study
2012
Early stages of nucleus-driven crystallization of the prototype phase change material Ge2Sb2Te5 have been studied by density functional/molecular dynamics simulations for amorphous samples (460 and 648 atoms) at 500, 600, and 700 K. All systems assumed a fixed cubic seed of 58 atoms and 6 vacancies. Crystallization occurs within 600 ps for the 460-atom system at 600 and 700 K, and signs of crystallization (nucleus growth, percolation) are present in the others. Crystallization is accompanied by an increase in the number of “ABAB squares” (A: Ge, Sb, B: Te), and atoms of all elements move significantly. There is no evidence of cavity movement to the crystal-glass interface, as suggested rece…
In situ observations of CH2Cl2 and CHCl3 show efficient transport pathways for very short-lived species into the lower stratosphere via the Asian and…
2022
Efficient transport pathways for ozone-depleting very short-lived substances (VSLSs) from their source regions into the stratosphere are a matter of current scientific debate; however they have yet to be fully identified on an observational basis. Understanding the increasing impact of chlorine-containing VSLSs (Cl-VSLSs) on stratospheric ozone depletion is important in order to validate and improve model simulations and future predictions. We report on a transport study using airborne in situ measurements of the Cl-VSLSs dichloromethane (CH2Cl2) and trichloromethane (chloroform, CHCl3) to derive a detailed description of two transport pathways from (sub)tropical source regions into the ext…
Study of η and η' Photoproduction at MAMI
2017
The reactions γp → ηp and γp → η0\ud p are measured from their thresholds up to the center-of-mass\ud energy W ¼ 1.96 GeV with the tagged-photon facilities at the Mainz Microtron, MAMI. Differential cross\ud sections are obtained with unprecedented statistical accuracy, providing fine energy binning and full\ud production-angle coverage. A strong cusp is observed in the total cross section for η photoproduction at the\ud energies in the vicinity of the η0 threshold, W ¼ 1896 MeV (Eγ ¼ 1447 MeV). Within the framework of a\ud revised ηMAID isobar model, the cusp, in connection with a steep rise of the η0 total cross section from its\ud threshold, can only be explained by a strong coupling of …
Daytime formation of nitrous acid at a coastal remote site in Cyprus indicating a common ground source of atmospheric HONO and NO
2016
Abstract. Characterization of daytime sources of nitrous acid (HONO) is crucial to understand atmospheric oxidation and radical cycling in the planetary boundary layer. HONO and numerous other atmospheric trace constituents were measured on the Mediterranean island of Cyprus during the CYPHEX campaign (CYPHEX = CYprus PHotochemical EXperiment) in summer 2014. Average volume mixing ratios of HONO were 35 pptv (±25 pptv) with a HONO/NOx ratio of 0.33, which was considerably higher than reported for most other rural and urban regions. Diel profiles of HONO showed peak values in the late morning (60±28 pptv around 09:00 local time), and persistently high mixing ratios during daytime (45±18 pptv…
Surface modification of mineral dust particles by sulphuric acid processing: implications for CCN and IN abilities
2011
Abstract. The ability of coated mineral dust particles to act as cloud condensation nuclei (CCN) and ice nuclei (IN) was investigated at LACIS (Leipzig Aerosol Cloud Interaction Simulator) during the FROST1- and FROST2-campaigns (Freezing of dust). Sulphuric acid was condensed on the particles which afterwards were optionally humidified, treated with ammonia vapour and/or heat. By means of aerosol mass spectrometry we found evidence that processing of mineral dust particles with sulphuric acid leads to surface modifications of the particles. These surface modifications are responsible for the observed reduction of the IN activation of the particles. The observed particle mass spectra sugges…
Can fruiting plants control animal behaviour and seed dispersal distance?
2015
In an Afrotropical forest, we tested the hypothesis that fleshy-fruit plants with interspecific dif-ferences in fruit quality and quantity affect ranging behaviour of their seed dispersal vector. Iffruiting plants could affect their dispersal vector, the plants also affect their seed dispersal distanceand eventually their plant population biology. From 2007 to 2011, we measured seed transportby georeference daily bonobo group movements via GPS. Seed dispersal distance was estimatedwith mechanistic model, using 1200 georeferenced dispersal events and the average seed transittime through bonobo (24.00 h). We compared dissemination for eight plant species that deal withthis trade-off: attracti…
Die Schuttvegetation der montanen und kollinen Zone des Pamir-Alai-Gebirges in Tadschikistan (Mittelasien)
2016
This paper is the continuation of a survey of the scree vegetation in alpine landscapes of western Pamir-Alai Mts in Tajikistan. In total, 105 phytosociological relevés were collected in the colline and montane belt in 2012‒2014, applying the Braun-Blanquet method. Phytocoenoses inhabiting mobile or fairly stabilised screes of different sizes of rock particles in the montane and colline zone are herein described. A hierarchical syntaxonomic synopsis of scree communities in the western Pamir Alai Mts is provided. The collected vegetation samples represent the majority of the variations among the phytocoenoses of gravel, pebble, cobble and rock block slides and screes. As a result of field su…
Diversitätsmuster in Graslandkomplexen von Auen mit unterschiedlicher Landschaftsheterogenität
2014
The complex topography of floodplains provides conditions for high diversity and density of transitional areas between different grassland plant communities. Nevertheless, transitions have been almost completely neglected in previous studies of diversity patterns in semi-natural floodplain grasslands. We analyzed α-, β- and γ-components of plant species diversity in transitional areas between neighbouring wet and dry grassland communities in two landscapes of the Gauja River floodplain (Latvia) differing in landscape heterogeneity created by land use history and current management type (grazing versus mowing). In total 9 transition areas and their adjacent vegetation were sampled in 1 m wid…
Leiobunum religiosum (Arachnida: Opiliones): first record for Germany
2010
L. religiosum Simon, 1879 was found at Mayen near Koblenz (Rhineland-Palatinate), Germany. This is the first record for Germany and is about 500 km from the known distribution area of the species in the southwestern Alps. The German population seems to be restricted to the ancient Roman quarry “Mayener Grubenfeld” where it is confined to stone walls and cave systems with balanced microclimatic conditions. Genital morphological structures were found to be very fragile, were easily deformed and therefore apparently variable. Difficulties in using these characters for taxonomy are discussed. Ecology, provenance and conservation status of the newly discovered population are considered.
Classification of limb defects
1998
Reference UPDUB-ARTICLE-1998-006doi:10.1002/(SICI)1096-8628(19980605)77:5 3.0.CO;2-J Record created on 2008-02-25, modified on 2017-05-12