2,287 research outputs found
Effects of abscisic acid on photosynthesis of protoplasts from Petunia hybrida
Protoplasts from plants are suitable experimental objects for investigations in which substances are taken up by cells, since chemicals can reach the cell surface directly. Therefore, it is convenient to use them for experiments concerned with effects of phytohormones on metabolism. So far, some work on the application of auxins 1-3 has been described, and recently we have made some investigations on the influence of zeatin on photosynthesis and respiration of isolated mesophyll protoplasts from Petunia.Inkubation mit Abscisinsäure verursacht bei Mesophyll-Protoplasten von Petunia hybrida einen Anstieg der Photosyntheserate
Epidemiology of Bluetongue Virus Serotype 8, Germany
In Germany, bluetongue disease had not been reported before 2006. During August 2006–August 2008, >24,000 bluetongue virus serotype 8 infections were reported, most (20,635) in 2007. In 2006 and 2007, respectively, case-fatality rates were 6.4% and 13.1% for cattle and 37.5% and 41.5% for sheep. Vaccination in 2008 decreased cases
Continual learning autoencoder training for a particle-in-cell simulation via streaming
The upcoming exascale era will provide a new generation of physics
simulations. These simulations will have a high spatiotemporal resolution,
which will impact the training of machine learning models since storing a high
amount of simulation data on disk is nearly impossible. Therefore, we need to
rethink the training of machine learning models for simulations for the
upcoming exascale era. This work presents an approach that trains a neural
network concurrently to a running simulation without storing data on a disk.
The training pipeline accesses the training data by in-memory streaming.
Furthermore, we apply methods from the domain of continual learning to enhance
the generalization of the model. We tested our pipeline on the training of a 3d
autoencoder trained concurrently to laser wakefield acceleration
particle-in-cell simulation. Furthermore, we experimented with various
continual learning methods and their effect on the generalization
Fluctuation Dissipation Ratio in Three-Dimensional Spin Glasses
We present an analysis of the data on aging in the three-dimensional Edwards
Anderson spin glass model with nearest neighbor interactions, which is well
suited for the comparison with a recently developed dynamical mean field
theory. We measure the parameter describing the violation of the
relation among correlation and response function implied by the fluctuation
dissipation theorem.Comment: LaTeX 10 pages + 4 figures (appended as uuencoded compressed
tar-file), THP81-9
Oxygen dynamics and transport in the Mediterranean sponge Aplysina aerophoba
The Mediterranean sponge Aplysina aerophoba kept in aquaria or cultivation tanks can stop pumping for several hours or even days. To investigate changes in the chemical microenvironments, we measured oxygen profiles over the surface and into the tissue of pumping and non-pumping A. aerophoba specimens with Clark-type oxygen microelectrodes (tip diameters 18–30 μm). Total oxygen consumption rates of whole sponges were measured in closed chambers. These rates were used to back-calculate the oxygen distribution in a finite-element model. Combining direct measurements with calculations of diffusive flux and modeling revealed that the tissue of non-pumping sponges turns anoxic within 15 min, with the exception of a 1 mm surface layer where oxygen intrudes due to molecular diffusion over the sponge surface. Molecular diffusion is the only transport mechanism for oxygen into non-pumping sponges, which allows total oxygen consumption rates of 6–12 μmol cm−3 sponge day−1. Sponges of different sizes had similar diffusional uptake rates, which is explained by their similar surface/volume ratios. In pumping sponges, oxygen consumption rates were between 22 and 37 μmol cm−3 sponge day−1, and the entire tissue was oxygenated. Combining different approaches of direct oxygen measurement in living sponges with a dynamic model, we can show that tissue anoxia is a direct function of the pumping behavior. The sponge-microbe system of A. aerophoba thus has the possibility to switch actively between aerobic and anaerobic metabolism by stopping the water flow for more than 15 min. These periods of anoxia will greatly influence physiological variety and activity of the sponge microbes. Detailed knowledge about the varying chemical microenvironments in sponges will help to develop protocols to cultivate sponge-associated microbial lineages and improve our understanding of the sponge-microbe-syste
Involvement of the epidermal growth factor receptor in the modulation of multidrug resistance in human hepatocellular carcinoma cells in vitro
<p>Abstract</p> <p>Background</p> <p>Hepatocellular carcinoma (HCC) is a molecular complex tumor with high intrinsic drug resistance. Recent evidence suggests an involvement of the tyrosine kinase pathway in the regulation of ATP-binding cassette protein (ABC-transport protein) mediated multidrug resistance in cancer cells. The aim of this study was to examine whether EGFR inhibition sensitizes HCCs to chemotherapy and to elucidate its mechanism.</p> <p>Results</p> <p>Chemotherapeutic treatment induces multidrug resistance and significantly increases ABC-transport protein expression and function in a time- and dose-dependent manner in HCC cells. Furthermore, cytostatic treatment increases the mRNA expression of tyrosine kinases and induces the phosphorylation of ERK. EGF activation of the tyrosine kinase pathway up-regulated the ABC-transport protein mRNA expression and enhanced the survival of resistant HCC cells. Consistent with these effects, inhibition of the EGFR using siRNA decreased the ABC-transport protein mRNA expression and inhibited the proliferation of resistant cells. Additional treatment with Gefitinib, a clinically approved EGFR inhibitor, caused a dose-dependent reversal of resistance to conventional chemotherapy.</p> <p>Conclusion</p> <p>The present study demonstrates that the multidrug resistance of HCC is modulated through the EGF-activated tyrosine kinase cascade. Consequentially, the restoration of chemosensitivity by EGFR inhibition may lead towards new tailored therapies in patients with highly resistant tumors.</p
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