1,206 research outputs found
An event-based architecture for solving constraint satisfaction problems
Constraint satisfaction problems (CSPs) are typically solved using
conventional von Neumann computing architectures. However, these architectures
do not reflect the distributed nature of many of these problems and are thus
ill-suited to solving them. In this paper we present a hybrid analog/digital
hardware architecture specifically designed to solve such problems. We cast
CSPs as networks of stereotyped multi-stable oscillatory elements that
communicate using digital pulses, or events. The oscillatory elements are
implemented using analog non-stochastic circuits. The non-repeating phase
relations among the oscillatory elements drive the exploration of the solution
space. We show that this hardware architecture can yield state-of-the-art
performance on a number of CSPs under reasonable assumptions on the
implementation. We present measurements from a prototype electronic chip to
demonstrate that a physical implementation of the proposed architecture is
robust to practical non-idealities and to validate the theory proposed.Comment: First two authors contributed equally to this wor
Sortenevaluierung in Deutschland zugelassener Wintergersten (Hordeum vulgare) hinsichtlich Flugbrand-Resistenz (Ustilago nuda) und Hartbrandresistenz (Ustilago hordei)
Dem Ökologischen Landbau stehen derzeit keine richtlinienkonformen Verfahren mit ausreichender Wirksamkeit und/oder arbeitstechnischer Effizienz zur Verfügung, um die gesetzlichen Auflagen in der Saatgut-Produktion einzuhalten. Schon mehr als drei bzw. fünf an Flug- und/oder Hartbrand erkrankte Ähren pro 150 qm in der Basis- bzw. Z-Saatguterzeugung führen zur Aberkennung der Vermehrungsbestände und somit zu beträchtlichen finanziellen Einbußen. Einen Ausweg böte der Anbau von resistenten Sorten. Hierzu wurden 2002-03 und 2004-05 die verfügbaren Handelssorten auf ihre Anfälligkeit gegenüber Hartbrand und seit 2000 insgesamt 274 Wintergerste-Genbankmuster bzw. Handelssorten gegenüber Gerstenflugbrand geprüft
Rhythmic inhibition allows neural networks to search for maximally consistent states
Gamma-band rhythmic inhibition is a ubiquitous phenomenon in neural circuits
yet its computational role still remains elusive. We show that a model of
Gamma-band rhythmic inhibition allows networks of coupled cortical circuit
motifs to search for network configurations that best reconcile external inputs
with an internal consistency model encoded in the network connectivity. We show
that Hebbian plasticity allows the networks to learn the consistency model by
example. The search dynamics driven by rhythmic inhibition enable the described
networks to solve difficult constraint satisfaction problems without making
assumptions about the form of stochastic fluctuations in the network. We show
that the search dynamics are well approximated by a stochastic sampling
process. We use the described networks to reproduce perceptual multi-stability
phenomena with switching times that are a good match to experimental data and
show that they provide a general neural framework which can be used to model
other 'perceptual inference' phenomena
Thermal Conductivity, Thermopower, and Figure of Merit of La_{1-x}Sr_xCoO_3
We present a study of the thermal conductivity k and the thermopower S of
single crystals of La_{1-x}Sr_xCoO_3 with 0<= x <= 0.3. For all Sr
concentrations La_{1-x}Sr_xCoO_3 has rather low k values, whereas S strongly
changes as a function of x. We discuss the influence of the temperature- and
the doping-induced spin-state transitions of the Co ions on both, S and k. From
S, k, and the electrical resistivity rho we derive the thermoelectric figure of
merit Z=S^2/(k*rho). For intermediate Sr concentrations we find notably large
values of Z indicating that Co-based materials could be promising candidates
for thermoelectric cooling.Comment: 7 pages, 5 figures included, submitted to Phys. Rev.
Asymmetric Squares as Standing Waves in Rayleigh-Benard Convection
Possibility of asymmetric square convection is investigated numerically using
a few mode Lorenz-like model for thermal convection in Boussinesq fluids
confined between two stress free and conducting flat boundaries. For relatively
large value of Rayleigh number, the stationary rolls become unstable and
asymmetric squares appear as standing waves at the onset of secondary
instability. Asymmetric squares, two dimensional rolls and again asymmetric
squares with their corners shifted by half a wavelength form a stable limit
cycle.Comment: 8 pages, 7 figure
Final
The present report reviews the fundamental right to privacy and data protection which shall be assured to individuals and the Directive 95/46/EC which provides more detailed rules on how to establish protection in the case of biometric data processing. The present framework does not seem apt to cope with all issues and problems raised by biometric applications. The limited recent case law of the European Court of Human Rights and the Court of Justice sheds some light on some relevant issues, but does not answer all questions. The report provides an analysis of the use of biometric data and the applicable current legal framework in six countries. The research demonstrates that in various countries, position is taken against the central storage of biometric data because of the various additional risks such storage entails. Furthermore, some countries stress the risks of the use of biometric characteristics which leave traces (such as e.g., fingerprint, face, voice…). In general, controllers of biometric applications receive limited clear guidance as to how implement biometric applications. Because of conflicting approaches, general recommendations are made in this report with regard to the regulation of central storage of biometric data and various other aspects, including the need for transparency of biometric systems
Strategien zur Bekämpfung von Brandkrankheiten bei Getreide im Ökologischen Landbau
Getreidebrände als saatgutübertragbare Erkrankungen der Ähre haben im Ökologischen Landbau stärkere Bedeutung erlangt, weil eine Beizung mit hochwirksamen Fungiziden unterbleibt. Eine Bekämpfung ist jedoch zwingend notwendig, weil in der Regel Ertragseinbußen eintreten und die Sporen toxikologisch bedenklich sind. Zudem droht der Saatgutvermehrung Schaden, denn bereits mehr als drei bzw. fünf befallene Pflanzen pro 150 m² führen zur Aberkennung des Basis- bzw. Z-Saatgutes. Resistente Sorten stehen kaum zur Verfügung, denn wegen der Saatbeizung bestand für die Züchtung seit Jahrzehnten keine Notwendigkeit, sich einer Resistenzzüchtung zu widmen. Das spiegelt sich auch in den Zulassungskriterien des Bundessortenamtes wider, wo die Anfälligkeit der Sorten auf Brandkrankheiten nicht berücksichtigt wird. Bei den relevanten Brandkrankheiten handelt es sich bei allen Triticum-Arten um Steinbrand (Tilletia tritici), Zwergsteinbrand (Tilletia controversa) und Flugbrand (Ustilago tritici), bei Gerste um Flugbrand (U. nuda) und Hartbrand (U. hordei) sowie bei Hafer um Flugbrand (U. avenae). Die Bekämpfung der Getreidebrände im Öko-Landbau ist spätestens seit der EU-Verordnung Nr. 1452/2003, welche die Verwendung von Saatgut aus ökologischem Anbau vorschreibt, eine vordringliche Aufgabe der Forschung. In Deutschland werden derzeit verschiedene Forschungsvorhaben zu dieser Problematik durchgeführt (Wilbois et al. 2005; Spieß 2006)
Distribution of graph-distances in Boltzmann ensembles of RNA secondary structures
Large RNA molecules often carry multiple functional domains whose spatial
arrangement is an important determinant of their function. Pre-mRNA splicing,
furthermore, relies on the spatial proximity of the splice junctions that can
be separated by very long introns. Similar effects appear in the processing of
RNA virus genomes. Albeit a crude measure, the distribution of spatial
distances in thermodynamic equilibrium therefore provides useful information on
the overall shape of the molecule can provide insights into the interplay of
its functional domains. Spatial distance can be approximated by the
graph-distance in RNA secondary structure. We show here that the equilibrium
distribution of graph-distances between arbitrary nucleotides can be computed
in polynomial time by means of dynamic programming. A naive implementation
would yield recursions with a very high time complexity of O(n^11). Although we
were able to reduce this to O(n^6) for many practical applications a further
reduction seems difficult. We conclude, therefore, that sampling approaches,
which are much easier to implement, are also theoretically favorable for most
real-life applications, in particular since these primarily concern long-range
interactions in very large RNA molecules.Comment: Peer-reviewed and presented as part of the 13th Workshop on
Algorithms in Bioinformatics (WABI2013
Modulated Phases in Spin-Peierls Systems
Lattice modulations in the high magnetic field phase and close to impurities
in spin-Peierls systems are considered and compared to experiment. Necessary
extensions of existing theories are proposed. The influence of zero-point
fluctuations on magnetic amplitudes is shown.Comment: 10 pages, 4 figures included, to appear in Advances in Solid State
Physics/Festkoerperprobleme Spring Conference 1999 of the DP
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