7,672 research outputs found
AMPHIPHILIC SIDEROPHORE MARINOBACTIN FOR FROTH FLOTATION PROCESS
The consumption of metallic raw materials increased in the last years. The coverage of
demand is getting more difficult, because both primary and secondary raw materials become more
and more complex. To find a solution, some new ways have to go, like the combination of
biotechnology with classic processes of processing methods
AMPHIPHILIC SIDEROPHORE MARINOBACTIN FOR FROTH FLOTATION PROCESS
The consumption of metallic raw materials increased in the last years. The coverage of
demand is getting more difficult, because both primary and secondary raw materials become more
and more complex. To find a solution, some new ways have to go, like the combination of
biotechnology with classic processes of processing methods
Price setting in a leading Swiss online supermarket
We study a newly released data set of scanner prices for food products in a large Swiss online supermarket. We find that average prices change about every two months, but when we exclude temporary sales, prices are extremely sticky, changing on average once every three years. Non-sale price behavior is broadly consistent with menu cost models of sticky prices. When we focus specifically on the behavior of sale prices, however, we find that the characteristics of price adjustment seems to be substantially at odds with standard theory.Pricing ; Profit
Characterizing synaptic conductance fluctuations in cortical neurons and their influence on spike generation
Cortical neurons are subject to sustained and irregular synaptic activity
which causes important fluctuations of the membrane potential (Vm). We review
here different methods to characterize this activity and its impact on spike
generation. The simplified, fluctuating point-conductance model of synaptic
activity provides the starting point of a variety of methods for the analysis
of intracellular Vm recordings. In this model, the synaptic excitatory and
inhibitory conductances are described by Gaussian-distributed stochastic
variables, or colored conductance noise. The matching of experimentally
recorded Vm distributions to an invertible theoretical expression derived from
the model allows the extraction of parameters characterizing the synaptic
conductance distributions. This analysis can be complemented by the matching of
experimental Vm power spectral densities (PSDs) to a theoretical template, even
though the unexpected scaling properties of experimental PSDs limit the
precision of this latter approach. Building on this stochastic characterization
of synaptic activity, we also propose methods to qualitatively and
quantitatively evaluate spike-triggered averages of synaptic time-courses
preceding spikes. This analysis points to an essential role for synaptic
conductance variance in determining spike times. The presented methods are
evaluated using controlled conductance injection in cortical neurons in vitro
with the dynamic-clamp technique. We review their applications to the analysis
of in vivo intracellular recordings in cat association cortex, which suggest a
predominant role for inhibition in determining both sub- and supra-threshold
dynamics of cortical neurons embedded in active networks.Comment: 9 figures, Journal of Neuroscience Methods (in press, 2008
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