19 research outputs found
Climatic and soil factors explain the two-dimensional spectrum of global plant trait variation
Plant functional traits can predict community assembly and ecosystem functioning and are thus widely used in global models of vegetation dynamics and land–climate feedbacks. Still, we lack a global understanding of how land and climate affect plant traits. A previous global analysis of six traits observed two main axes of variation: (1) size variation at the organ and plant level and (2) leaf economics balancing leaf persistence against plant growth potential. The orthogonality of these two axes suggests they are differently influenced by environmental drivers. We find that these axes persist in a global dataset of 17 traits across more than 20,000 species. We find a dominant joint effect of climate and soil on trait variation. Additional independent climate effects are also observed across most traits, whereas independent soil effects are almost exclusively observed for economics traits. Variation in size traits correlates well with a latitudinal gradient related to water or energy limitation. In contrast, variation in economics traits is better explained by interactions of climate with soil fertility. These findings have the potential to improve our understanding of biodiversity patterns and our predictions of climate change impacts on biogeochemical cycles
Dielectric signature of charge order in lanthanum nickelates
Three charge-ordering lanthanum nickelates La2-xAxNiO4, substituted with
specific amounts of A = Sr, Ca, and Ba to achieve commensurate charge order,
are investigated using broadband dielectric spectroscopy up to GHz frequencies.
The transition temperatures of the samples are characterized by additional
specific heat and magnetic susceptibility measurements. We find colossal
magnitudes of the dielectric constant for all three compounds and strong
relaxation features, which partly are of Maxwell-Wagner type arising from
electrode polarization. Quite unexpectedly, the temperature-dependent colossal
dielectric constants of these materials exhibit distinct anomalies at the
charge-order transitions.Comment: 7 pages, 6 figure
Climatic and soil factors explain the two-dimensional spectrum of global plant trait variation
Plant functional traits can predict community assembly and ecosystem functioning and are thus widely used in global models of vegetation dynamics and land–climate feedbacks. Still, we lack a global understanding of how land and climate affect plant traits. A previous global analysis of six traits observed two main axes of variation: (1) size variation at the organ and plant level and (2) leaf economics balancing leaf persistence against plant growth potential. The orthogonality of these two axes suggests they are differently influenced by environmental drivers. We find that these axes persist in a global dataset of 17 traits across more than 20,000 species. We find a dominant joint effect of climate and soil on trait variation. Additional independent climate effects are also observed across most traits, whereas independent soil effects are almost exclusively observed for economics traits. Variation in size traits correlates well with a latitudinal gradient related to water or energy limitation. In contrast, varia- tion in economics traits is better explained by interactions of climate with soil fertility. These findings have the potential to improve our understanding of biodiversity patterns and our predictions of climate change impacts on biogeochemical cycles.Environmental Biolog
COMPACT LOW-PROFILE PATCH ANTENNA FOR MEDICAL BODY AREA NETWORKS AT 868 MHz
During hypersonic flight the temperatures on the vehicle can reach very high values in certain locations. A hypersonic flight vehicle needs to be designed aerodynamically efficient. That results in rather small nose and leading edge radii which drives up thermal loads due to the fact that the loads depend on the curvature radius of these elements. Therefore thermal protections is required for these elements. However, even ceramics reach their use temperature limits when e.g. the leading edge radius of a space plane is in the order of only a few centimeters. Transpiration cooling could be a means to handle the thermal loads in certain critical locations for a hypersonic flight vehicle. This paper describes the loads derived for a conceptual space plane vehicle, the SpaceLiner, and also reports on the initial tests for transpiration cooling of ceramic matrix composites in the hypersonic flow of an arc jet facility