1,064 research outputs found
The effect of immigrants on natives' incomes through the use of capital / BEBR No.878
Includes bibliographical references (p. 19)
Parameter Optimisation of a Virtual Synchronous Machine in a Microgrid
Parameters of a virtual synchronous machine in a small microgrid are
optimised. The dynamical behaviour of the system is simulated after a
perturbation, where the system needs to return to its steady state. The cost
functional evaluates the system behaviour for different parameters. This
functional is minimised by Parallel Tempering. Two perturbation scenarios are
investigated and the resulting optimal parameters agree with analytical
predictions. Dependent on the focus of the optimisation different optima are
obtained for each perturbation scenario. During the transient the system leaves
the allowed voltage and frequency bands only for a short time if the
perturbation is within a certain range.Comment: 17 pages, 5 figure
Morphogen-defined patterning of Escherichia coli enabled by an externally tunable band-pass filter
<p>Abstract</p> <p>Background</p> <p>Gradients of morphogens pattern cell fate – a phenomenon that is especially important during development. A simple model system for studying how morphogens pattern cell behavior would overcome difficulties inherent in the study of natural morphogens <it>in vivo</it>. A synthetic biology approach to building such a system is attractive.</p> <p>Results</p> <p>Using an externally-tunable band-pass filter paradigm, we engineered <it>Escherichia coli </it>cells to function as a model system for the study of how multiple morphogens can pattern cell behavior. We demonstrate how our system exhibits behavior such as morphogen crosstalk and how the cells' growth and fluorescence can be patterned in a number of complex patterns. We extend our cell patterning from 2D cultures on the surface of plates to 3D cultures in soft agarose medium.</p> <p>Conclusion</p> <p>Our system offers a convenient, well-defined model system for fundamental studies on how multiple morphogen gradients can affect cell fate and lead to pattern formation. Our design principles could be applied to eukaryotic cells to develop other models systems for studying development or for enabling the patterning of cells for applications such as tissue engineering and biomaterials.</p
Coulomb charging energy for arbitrary tunneling strength
The Coulomb energy of a small metallic island coupled to an electrode by a
tunnel junction is investigated. We employ Monte Carlo simulations to determine
the effective charging energy for arbitrary tunneling strength. For small
tunneling conductance, the data agree with analytical results based on a
perturbative treatment of electron tunneling, while for very strong tunneling
recent semiclassical results for large conductance are approached. The data
allow for an identification of the range of validity of various analytical
predictions.Comment: 4 pages REVTeX, incl 3 figures, to appear in Europhys.Let
Asymptotic behaviour of multiple scattering on infinite number of parallel demi-planes
The exact solution for the scattering of electromagnetic waves on an infinite
number of parallel demi-planes has been obtained by J.F. Carlson and A.E. Heins
in 1947 using the Wiener-Hopf method. We analyze their solution in the
semiclassical limit of small wavelength and find the asymptotic behaviour of
the reflection and transmission coefficients. The results are compared with the
ones obtained within the Kirchhoff approximation
In Vitro Recombination of Non-Homologous Genes Can Result in Gene Fusions that Confer a Switching Phenotype to Cells
Regulation of protein activity is central to the complexity of life. The ability to regulate protein activity through exogenously added molecules has biotechnological/biomedical applications and offers tools for basic science. Such regulation can be achieved by establishing a means to modulate the specific activity of the protein (i.e. allostery). An alternative strategy for intracellular regulation of protein activity is to control the amount of protein through effects on its production, accumulation, and degradation. We have previously demonstrated that the non-homologous recombination of the genes encoding maltose binding protein (MBP) and TEM1 β-lactamase (BLA) can result in fusion proteins in which β-lactamase enzyme activity is allosterically regulated by maltose. Here, through use of a two-tiered genetic selection scheme, we demonstrate that such recombination can result in genes that confer maltose-dependent resistance to β-lactam even though they do not encode allosteric enzymes. These ‘phenotypic switch’ genes encode fusion proteins whose accumulation is a result of a specific interaction with maltose. Phenotypic switches represent an important class of proteins for basic science and biotechnological applications in vivo
Differentiation of Candida dubliniensis from Candida albicans with the use of killer toxins
The aim of this study was to report the ability of killer toxins, previously used as biotyping techniques, as a new tool to differentiate C. albicans from C. dubliniensis. The susceptibility of C. albicans and C. dubliniensis to killer toxins ranged from 33.9 to 93.3% and from 6.67 to 93.3%, respectively.Avaliou-se a capacidade das toxinas killer, previamente utilizadas na biotipagem de C. albicans, como método para diferenciar C. albicans de C. dubliniensis. A susceptibilidade de C. albicans e C. dubliniensis às toxinas killer variou de 33,9% a 93,3% para C. albicans e de 6,67% a 93,3% para C. dubliniensis
162 (PB-075) Poster - Who is at risk of developing breast cancer-related fatigue:A prediction study
Path integrals, particular kinds, and strange things
This paper describes a path integral formulation of the free energy
principle. The ensuing account expresses the paths or trajectories that a
particle takes as it evolves over time. The main results are a method or
principle of least action that can be used to emulate the behaviour of
particles in open exchange with their external milieu. Particles are defined by
a particular partition, in which internal states are individuated from external
states by active and sensory blanket states. The variational principle at hand
allows one to interpret internal dynamics - of certain kinds of particles - as
inferring external states that are hidden behind blanket states. We consider
different kinds of particles, and to what extent they can be imbued with an
elementary form of inference or sentience. Specifically, we consider the
distinction between dissipative and conservative particles, inert and active
particles and, finally, ordinary and strange particles. Strange particles (look
as if they) infer their own actions, endowing them with apparent autonomy or
agency. In short - of the kinds of particles afforded by a particular partition
- strange kinds may be apt for describing sentient behaviour.Comment: 31 pages (excluding references), 6 figure
Dynamics in population heterogeneity during batch and continuous fermentation of Saccharomyces cerevisiae
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