1,553 research outputs found
Preserving the measure of compatibility between quantum states
In this paper after defining the abstract concept of compatibility-like
functions on quantum states, we prove that every bijective transformation on
the set of all states which preserves such a function is implemented by an
either unitary or antiunitary operator.Comment: 11 pages, submitted for publicatio
k-Trails: Recognition, Complexity, and Approximations
The notion of degree-constrained spanning hierarchies, also called k-trails,
was recently introduced in the context of network routing problems. They
describe graphs that are homomorphic images of connected graphs of degree at
most k. First results highlight several interesting advantages of k-trails
compared to previous routing approaches. However, so far, only little is known
regarding computational aspects of k-trails.
In this work we aim to fill this gap by presenting how k-trails can be
analyzed using techniques from algorithmic matroid theory. Exploiting this
connection, we resolve several open questions about k-trails. In particular, we
show that one can recognize efficiently whether a graph is a k-trail.
Furthermore, we show that deciding whether a graph contains a k-trail is
NP-complete; however, every graph that contains a k-trail is a (k+1)-trail.
Moreover, further leveraging the connection to matroids, we consider the
problem of finding a minimum weight k-trail contained in a graph G. We show
that one can efficiently find a (2k-1)-trail contained in G whose weight is no
more than the cheapest k-trail contained in G, even when allowing negative
weights.
The above results settle several open questions raised by Molnar, Newman, and
Sebo
Исследование структуры древостоя на исторической экспериментальной площади
Защитные леса не подразумевают выборочных рубок, но выборочные рубки помогают поддерживать их наиболее эффективно. Так как раньше в Венгрии не было больших площадей регулируемых лесов, система выборочных рубок используется для перевода в эту категорию ранее одновозрастных лесов. Процесс трансформации очень длительный и может занять века. Трансформация лесного участка Sopron 182/B началась в 1937 г. и теперь находится на финальных стадиях. Разнообразно структурированный древостой позволяет нам анализировать процесс в реальном лесу, что может помочь на практике. Обработка данных пока на начальном этапе, и после корректировки позиций появится больше возможностей для применения ГИС-технологи
More frequencies of KUV 02464+3239
Preliminary results on KUV 02464+3239, a pulsating DA white dwarf are
presented. Located near the red edge of the DAV instability strip, KUV
02464+3239 shows large amplitude and long period pulsation modes. Up to now
only one mode was known from a 50-minute-long light curve. Our more extended
observations allowed the identification of three additional frequencies. The
presence of previously known harmonics were confirmed and weak subharmonics are
also noticeable at some parts of the light curve. This suggests the dominance
of nonlinear pulsation effects from time to time.Comment: 3 pages, 3 eps figures; has been accepted for publication in
Astronomische Nachrichten (Vol. 8, 2007), proceedings of the
British-Hungarian-French N+N+N Workshop for Young Researcher
Hints of incomplete thermalization in RHIC data
The large elliptic flow observed in Au-Au collisions at RHIC is often put
forward as a compelling evidence for the formation of a strongly-interacting
quark-gluon plasma. The main argument is that the measured elliptic flow is as
large as the value given by fluid-dynamics models that assume complete
thermalization. It is argued that this claim may not be justified, since a
detailed examination of experimental data rather suggests that the system
created is not fully equilibrated at the time when anisotropic flow develops.Comment: 8 pages, 2 eps-figures, Talk given at the Workshop on QGP
Thermalization (QGPTH05), Vienna, 10-12 Aug 200
Generic stability of dissipative non-relativistic and relativistic fluids
The linear stability of the homogeneous equilibrium of non-relativistic
fluids with mass flux and special relativistic fluids with the absolute value
of the energy vector as internal energy is investigated. It is proved that the
equilibrium is asymptotically stable in both cases due to purely thermodynamic
restrictions; the only requirements are the thermodynamic stability and the
nonnegativity of the transport coefficients.Comment: 22 page
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