Comparison of customer satisfaction in different types of distribution channels of horticultural products in Austria and Bavaria

Paper prepared for presentation at the First Symposium on Horticulture in Europe (SHE), 17th to 20th February 2008 at Vienna/Austria held under the aegis of ALVA, APH, BNL-SHS, DGG, GSHS, IOH, INRA, NJF, PSHS, SECH, SOI and the International Society for Horticultural ScienceConsumer Behaviour, Horticulture, Austria, Germany, Consumer/Household Economics, Marketing,

The widespread role of non-enzymatic reactions in cellular metabolism.

Enzymes shape cellular metabolism, are regulated, fast, and for most cases specific. Enzymes do not however prevent the parallel occurrence of non-enzymatic reactions. Non-enzymatic reactions were important for the evolution of metabolic pathways, but are retained as part of the modern metabolic network. They divide into unspecific chemical reactivity and specific reactions that occur either exclusively non-enzymatically as part of the metabolic network, or in parallel to existing enzyme functions. Non-enzymatic reactions resemble catalytic mechanisms as found in all major enzyme classes and occur spontaneously, small molecule (e.g. metal-) catalyzed or light-induced. The frequent occurrence of non-enzymatic reactions impacts on stability and metabolic network structure, and has thus to be considered in the context of metabolic disease, network modeling, biotechnology and drug design.We acknowledge funding from the Wellcome Trust (RG 093735/Z/10/Z), the ERC (starting Grant 260809). Markus A Keller is supported by the Austrian Science Funds by an Erwin Schroeder postdoctoral fellowship (FWF, J 3341). Markus Ralser is a Wellcome Trust Research Career Development and Wellcome-Beit Prize fellow.This paper was originally published in Current Opinion in Biotechnology (Keller MA, Piedrafita G, Ralser M, Current Opinion in Biotechnology 2015, 34, 153–161, doi:10.1016/j.copbio.2014.12.020)

The Impact of Non-Enzymatic Reactions and Enzyme Promiscuity on Cellular Metabolism during (Oxidative) Stress Conditions.

Cellular metabolism assembles in a structurally highly conserved, but functionally dynamic system, known as the metabolic network. This network involves highly active, enzyme-catalyzed metabolic pathways that provide the building blocks for cell growth. In parallel, however, chemical reactivity of metabolites and unspecific enzyme function give rise to a number of side products that are not part of canonical metabolic pathways. It is increasingly acknowledged that these molecules are important for the evolution of metabolism, affect metabolic efficiency, and that they play a potential role in human disease-age-related disorders and cancer in particular. In this review we discuss the impact of oxidative and other cellular stressors on the formation of metabolic side products, which originate as a consequence of: (i) chemical reactivity or modification of regular metabolites; (ii) through modifications in substrate specificity of damaged enzymes; and (iii) through altered metabolic flux that protects cells in stress conditions. In particular, oxidative and heat stress conditions are causative of metabolite and enzymatic damage and thus promote the non-canonical metabolic activity of the cells through an increased repertoire of side products. On the basis of selected examples, we discuss the consequences of non-canonical metabolic reactivity on evolution, function and repair of the metabolic network.Work in the Ralser lab is funded from the Wellcome Trust (RG 093735/Z/10/Z), the ERC (Starting grant 260809). Markus A. Keller is supported by the Austrian Science Funds by an Erwin Schrödinger postdoctoral fellowship (FWF, J 3341). Markus Ralser is a Wellcome Trust Research Career Development and Wellcome-Beit Prize fellow.This is the final version of the article. It first appeared from MDPI via http://dx.doi.org/10.3390/biom503210

Nd-doped polymer waveguide amplifiers at 850-930 nm

Nd-complex-doped, polymer channel waveguides were realized on thermally oxidized silicon wafers by a simple fabrication procedure. Broadband optical gain was demonstrated at 850-930 nm. Internal net gain up to 5.3 dB/cm was obtained at 850 nm, which is very promising for optical amplification in optical backplanes. With this result a route toward low-cost integrated waveguide amplifiers for optical interconnects has been opened

The coherence-incoherence crossover and the mass-renormalization puzzles in Sr2RuO4

We calculate the electronic structure of Sr2RuO4, treating correlations in the framework of dynamical mean-field theory. The approach successfully reproduces several experimental results and explains the key properties of this material: the anisotropic mass renormalization of quasiparticles and the crossover into an incoherent regime at a low temperature. While the orbital differentiation originates from the proximity of the van Hove singularity, strong correlations are caused by the Hund's coupling. The generality of this mechanism for other correlated materials is pointed out.Comment: 4 pages, 4 figs, minor changes, published versio

Mathematical modeling of the Drosophila neuromuscular junction

Poster presentation: An important challenge in neuroscience is understanding how networks of neurons go about processing information. Synapses are thought to play an essential role in cellular information processing however quantitative and mathematical models of the underlying physiologic processes that occur at synaptic active zones are lacking. We are generating mathematical models of synaptic vesicle dynamics at a well-characterized model synapse, the Drosophila larval neuromuscular junction. This synapse's simplicity, accessibility to various electrophysiological recording and imaging techniques, and the genetic malleability intrinsic to Drosophila system make it ideal for computational and mathematical studies. We have employed a reductionist approach and started by modeling single presynaptic boutons. Synaptic vesicles can be divided into different pools; however, a quantitative understanding of their dynamics at the Drosophila neuromuscular junction is lacking [4]. We performed biologically realistic simulations of high and low release probability boutons [3] using partial differential equations (PDE) taking into account not only the evolution in time but also the spatial structure in two dimensions (the extension to three dimensions will be implemented soon). PDEs are solved using UG, a program library for the calculation of multi-dimensional PDEs solved using a finite volume approach and implicit time stepping methods leading to extended linear equation systems be solvedwith multi-grid methods [3,4]. Numerical calculations are done on multi-processor computers for fast calculations using different parameters in order to asses the biological feasibility of different models. In preliminary simulations, we modeled vesicle dynamics as a diffusion process describing exocytosis as Neumann streams at synaptic active zones. The initial results obtained with these models are consistent with experimental data. However, this should be regarded as a work in progress. Further refinements will be implemented, including simulations using morphologically realistic geometries which were generated from confocal scans of the neuromuscular junction using NeuRA (a Neuron Reconstruction Algorithm). Other parameters such as glutamate diffusion and reuptake dynamics, as well as postsynaptic receptor kinetics will be incorporated as well

Pure single photons from a trapped atom source

Single atoms or atom-like emitters are the purest source of on-demand single photons, they are intrinsically incapable of multi-photon emission. To demonstrate this degree of purity we have realized a tunable, on-demand source of single photons using a single ion trapped at the common focus of high numerical aperture lenses. Our trapped-ion source produces single-photon pulses at a rate of 200 kHz with g$^2(0) = (1.9 \pm 0.2) \times 10^{-3}$, without any background subtraction. The corresponding residual background is accounted for exclusively by detector dark counts. We further characterize the performance of our source by measuring the violation of a non-Gaussian state witness and show that its output corresponds to ideal attenuated single photons. Combined with current efforts to enhance collection efficiency from single emitters, our results suggest that single trapped ions are not only ideal stationary qubits for quantum information processing, but promising sources of light for scalable optical quantum networks.Comment: 7 pages plus one page supplementary materia

¿contingencia o necesidad? schelling y hegel acerca del estatus modal del espacio lógico

Palabras pronunciadas por Markus Gabriel en el marco del encuentro internacional "Presente del idealismo alemán" organizado por el Departamento de Filosofía de la Universidad Nacional de Colombia. Conferencia que tuvo lugar el 9 de octubre de 2009