3,871 research outputs found
Anmeldelse af "Krigeren, borgeren og taberen"
"Krigeren, borgeren og taberen" / af Ole Thyssen, Henrik Dahl. - 2. oplag. [Kbh.] : Gyldendal, 2006. 243 sider
Exact Periodic Solutions of Shells Models of Turbulence
We derive exact analytical solutions of the GOY shell model of turbulence. In
the absence of forcing and viscosity we obtain closed form solutions in terms
of Jacobi elliptic functions. With three shells the model is integrable. In the
case of many shells, we derive exact recursion relations for the amplitudes of
the Jacobi functions relating the different shells and we obtain a Kolmogorov
solution in the limit of infinitely many shells. For the special case of six
and nine shells, these recursions relations are solved giving specific analytic
solutions. Some of these solutions are stable whereas others are unstable. All
our predictions are substantiated by numerical simulations of the GOY shell
model. From these simulations we also identify cases where the models exhibits
transitions to chaotic states lying on strange attractors or ergodic energy
surfaces.Comment: 25 pages, 7 figure
On the Grothendieck Theorem for jointly completely bounded bilinear forms
We show how the proof of the Grothendieck Theorem for jointly completely
bounded bilinear forms on C*-algebras by Haagerup and Musat can be modified in
such a way that the method of proof is essentially C*-algebraic. To this
purpose, we use Cuntz algebras rather than type III factors. Furthermore, we
show that the best constant in Blecher's inequality is strictly greater than
one.Comment: 9 pages, minor change
Confinement effects from interacting chromo-magnetic and axion fields
We study a non-Abelian gauge theory with a pseudo scalar coupling \phi
\epsilon ^{\mu \nu \alpha \beta} F_{\mu \nu}^a F_{\alpha \beta}^a in the case
where a constant chromo-electric, or chromo-magnetic, strength expectation
value is present. We compute the interaction potential within the framework of
gauge-invariant, path-dependent, variables formalism. While in the case of a
constant chromo-electric field strength expectation value the static potential
remains Coulombic, in the case of a constant chromo-magnetic field strength the
potential energy is the sum of a Coulombic and a linear potentials, leading to
the confinement of static charges.Comment: 12 pages, no figures, published versio
Real Interquark Potential Between a Heavy and a Light Quark at All Distances
We point out that in infinite spacetime dimensions, the singularity in the
interquark potential at small distances disappears if the string is anchored at
one end to a heavy quark, at the other end to a light quark. This suggests that
if quarks are placed at the end of strings some unphysical features such as
tachyon states may be absent also in in finite dimensions.Comment: Texfile + fig.tex +fig.eps,
http://www.physik.fu-berlin.de/./kleinert.htm
Adaptable Value-Set Analysis for Low-Level Code
This paper presents a framework for binary code analysis that uses only SAT-based algorithms. Within the framework, incremental SAT solving is used to perform a form of weakly relational value-set analysis in a novel way, connecting the expressiveness of the value sets to computational complexity. Another key feature of our framework is that it translates the semantics of binary code into an intermediate representation. This allows for a straightforward translation of the program semantics into Boolean logic and eases the implementation efforts, too. We show that leveraging the efficiency of contemporary SAT solvers allows us to prove interesting properties
about medium-sized microcontroller programs
New Developments in Biotechnology and IPR in Aquaculture – Are They Sustainable?
The objective of this chapter is to give an overview and analysis of the current trends and
developments in biotechnology in aquaculture research and management. The technological
developments along with structural changes in the aquaculture sector may affect access and
intellectual property rights (IPR) regimes. These issues will be discussed in a wide perspective involving both short and long-term biological effects, ethical and other social aspects (economic, legal and political issues), including their partly inherent contradictions needing compromising for sustainable development. The chapter will focus on current biological challenges within aquaculture as a growing food production sector, with less emphasis on external effects such as environmental effects. Cases from farmed salmon and cod in Norway in addition to shrimp and tilapia in Asia will be highlighted
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