University of Vienna

About: University of Vienna is a education organization based out in Vienna, Austria. It is known for research contribution in the topics: Population & Context (language use). The organization has 44686 authors who have published 95840 publications receiving 2907492 citations.

Modelling climate change-driven treeline shifts: relative effects of temperature increase, dispersal and invasibility

Abstract: Summary 1Global warming will probably shift treelines upslope in alpine areas and towards the pole in arctic environments. However, responses of regional treelines to climatic trends over the last century do not show any clear trends. We hypothesize that these equivocal responses may partly be caused by limitation of dispersal and/or recruitment that is species-specific to particular trees with potentially expanding ranges. 2To test this hypothesis, we established and parameterized a temporally and spatially explicit model of plant spread and analysed its sensitivity to: (a) variation in predicted climatic trends; (b) the spatial distribution of recruits around a seed source; and (c) variation in the resistance of resident non-woody vegetation to invasion. We used data from a high mountain landscape of the Northern Calcareous Alps in Austria where the treeline is dominated by Pinus mugo Turra, a shrubby pine. 3Low growth rates and long generation times, together with considerable dispersal and recruitment limitation, resulted in an overall slow range expansion under various climate-warming scenarios. 4Running the model for 1000 years predicted that the area covered by pines will increase from 10% to between 24% and 59% of the study landscape. 5The shape of the dispersal curve and spatial patterns of competitively controlled recruitment suppression affect range size dynamics at least as severely as does variation in assumed future mean annual temperature (between 0 °C and 2 °C above the current mean). Moreover, invasibility and shape of the dispersal curve interact with each other due to the spatial patterns of vegetation cover in the region. 6Ambiguous transient responses of individual treeline systems may thus originate not only from variation in regional climatic trends but also from differences in species’ dispersal and recruitment behaviour and in the intensity and pattern of resistance of resident alpine vegetation to invasion.

Management of bleeding following major trauma: a European guideline.

Abstract: Introduction Evidence-based recommendations can be made with respect to many aspects of the acute management of the bleeding trauma patient, which when implemented may lead to improved patient outcomes.

Assessing the quality of the random phase approximation for lattice constants and atomization energies of solids

Abstract: We present lattice constants, bulk moduli, and atomization energies of solids using the correlation energy evaluated within the adiabatic connection fluctuation-dissipation framework and applying the random-phase approximation. Recently, we have shown [Phys. Rev. Lett. 103, 056401 (2009)] that geometrical properties and heats of formation are well described within this approximation. We extend this study to a larger set of materials and focus on the treatment of metals and the effect introduced by the frozen-core approximation.

Quantum interference of large organic molecules

Abstract: The wave nature of matter is a key ingredient of quantum physics and yet it defies our classical intuition. First proposed by Louis de Broglie a century ago, it has since been confirmed with a variety of particles from electrons up to molecules. Here we demonstrate new high-contrast quantum experiments with large and massive tailor-made organic molecules in a near-field interferometer. our experiments prove the quantum wave nature and delocalization of compounds composed of up to 430 atoms, with a maximal size of up to 60 A, masses up to m = 6,910 AMU and de Broglie wavelengths down to λdB = h/mv1 pm. We show that even complex systems, with more than 1,000 internal degrees of freedom, can be prepared in quantum states that are sufficiently well isolated from their environment to avoid decoherence and to show almost perfect coherence.