320 research outputs found
EMC3-Eirene simulations of the impact of Magnetic Perturbations on the neutral particle recycling in ASDEX Upgrade
Flow profiling of a surface acoustic wave nanopump
The flow profile in a capillary gap and the pumping efficiency of an acoustic
micropump employing Surface Acoustic Waves is investigated both experimentally
and theoretically. Such ultrasonic surface waves on a piezoelectric substrate
strongly couple to a thin liquid layer and generate an internal streaming
within the fluid. Such acoustic streaming can be used for controlled agitation
during, e.g., microarray hybridization. We use fluorescence correlation
spectroscopy and fluorescence microscopy as complementary tools to investigate
the resulting flow profile. The velocity was found to depend on the applied
power somewhat weaker than linearly and to decrease fast with the distance from
the ultrasound generator on the chip.Comment: 12 pages 20 figure
Core transport and pedestal characteristics of nitrogen seeded H-mode discharges in ASDEX Upgrade
First EMC3-Eirene simulations of the impact of the edge magnetic perturbations at ASDEX Upgrade compared with the experiment
Studies of edge localized mode mitigation with new active in-vessel saddle coils in ASDEX Upgrade
Access conditions for ELM mitigation with non-axisymmetric magnetic perturbations in ASDEX Upgrade
Charge-induced conformational changes of dendrimers
We study the effect of chargeable monomers on the conformation of dendrimers
of low generation by computer simulations, employing bare Coulomb interactions.
The presence of the latter leads to an increase in size of the dendrimer due to
a combined effect of electrostatic repulsion and the presence of counterions
within the dendrimer, and also enhances a shell-like structure for the monomers
of different generations. In the resulting structures the bond-length between
monomers, especially near the center, will increase to facilitate a more
effective usage of space in the outer-regions of the dendrimer.Comment: 7 pages, 12 figure
Missing rings in Pinus halepensis
Climate predictions for the Mediterranean Basin include increased temperatures, decreased precipitation, and increased frequency of extreme climatic events (ECE). These conditions are associated with decreased tree growth and increased vulnerability to pests and diseases. The anatomy of tree rings responds to these environmental conditions. Quantitatively, the width of a tree ring is largely determined by the rate and duration of cell division by the vascular cambium. In the Mediterranean climate, this division may occur throughout almost the entire year. Alternatively, cell division may cease during relatively cool and dry winters, only to resume in the same calendar year with milder temperatures and increased availability of water. Under particularly adverse conditions, no xylem may be produced in parts of the stem, resulting in a missing ring (MR). A dendrochronological network of Pinus halepensis was used to determine the relationship of MR to ECE. The network consisted of 113 sites, 1,509 trees, 2,593 cores, and 225,428 tree rings throughout the distribution range of the species. A total of 4,150 MR were identified. Binomial logistic regression analysis determined that MR frequency increased with increased cambial age. Spatial analysis indicated that the geographic areas of south-eastern Spain and northern Algeria contained the greatest frequency of MR. Dendroclimatic regression analysis indicated a non-linear relationship of MR to total monthly precipitation and mean temperature. MR are strongly associated with the combination of monthly mean temperature from previous October till current February and total precipitation from previous September till current May. They are likely to occur with total precipitation lower than 50 mm and temperatures higher than 5°C. This conclusion is global and can be applied to every site across the distribution area. Rather than simply being a complication for dendrochronology, MR formation is a fundamental response of trees to adverse environmental conditions. The demonstrated relationship of MR formation to ECE across this dendrochronological network in the Mediterranean basin shows the potential of MR analysis to reconstruct the history of past climatic extremes and to predict future forest dynamics in a changing climate
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