9,867 research outputs found
Crucial Words and the Complexity of Some Extremal Problems for Sets of Prohibited Words
We introduced the notation of a set of prohibitions and give definitions of a
complete set and a crucial word with respect to a given set of prohibitions. We
consider 3 particular sets which appear in different areas of mathematics and
for each of them examine the length of a crucial word. One of these sets is
proved to be incomplete. The problem of determining lengths of words that are
free from a set of prohibitions is shown to be NP-complete, although the
related problem of whether or not a given set of prohibitions is complete is
known to be effectively solvable.Comment: 16 page
Volume discharge in a gas, excited by an electron beam under conditions of nonuniform ionization
Volume discharge in gases excited by electron beams is discussed. The steady state electric field distribution is derived. The voltage-current and energy characteristics are described
Towards an Understanding of the New Charm and Charm-Strange Mesons
The observation of the D_{sJ}^*(2317), D_{sJ}(2460), and SELEX D^*_{sJ}(2632)
states with properties differing considerably from what was expected has led to
a renewed interest in hadron spectroscopy. In addition to these states,
non-strange partners of the D_{sJ} states have also been observed.
Understanding the D_0^* and D_1' states can provide important insights into the
D_{sJ} states. In this contribution I examine quark model predictions for the
D_0^* and D_1' states and discuss experimental measurements that can shed light
on them. I find that these states are well described as the broad, j=1/2
non-strange charmed P-wave mesons. In the latter part of this writeup I discuss
the c bar{s} possibilities for the SELEX D^*_{sJ}(2632) and measurements that
can shed light on it.Comment: Talk presented at the 1st Meeting of the APS Topical Group on
Hadronic Physics (Fermilab, Oct 24-26, 2004). 4 pages uses jpcon
Peculiarities of formation of the active surface of Cu-modified CrOx/Al2O3 catalysts for dehydrogenation of isobutane to isobutylene
Carbon Friction Pair in Total Hip Replacement
The article examines the advantages of a new pair of friction of the hip joint endoprosthesis made of pyrolytic carbon. The physico-mechanical and tribological characteristics of the material and their comparison with other materials used in the friction pair of hip joint endoprostheses are presented. Information is presented about the making of a material and its strength characteristics and the results of mathematical modeling of a friction pair. The results of a comparative research of the durability between a carbon pair of friction and a ceramic pair of friction
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