7,427 research outputs found
Equianalytic and equisingular families of curves on surfaces
We consider flat families of reduced curves on a smooth surface S such that
each member C has the same number of singularities of fixed singularity types
and the corresponding (locally closed) subscheme H of the Hilbert scheme of S.
We are mainly concerned with analytic resp. topological singularity types and
give a sufficient condition for the smoothness of H (at C). Our results for
S=P^2 seem to be quite sharp for families of cuves of small degree d.Comment: LaTeX v 2.0
On the first Gaussian map for Prym-canonical line bundles
We prove by degeneration to Prym-canonical binary curves that the first
Gaussian map of the Prym canonical line bundle is
surjective for the general point [C,A] of R_g if g >11, while it is injective
if g < 12.Comment: To appear in Geometriae Dedicata. arXiv admin note: text overlap with
arXiv:1105.447
Lattice location and stability of implanted Cu in ZnO
The lattice location of copper in single-crystalline zinc oxide was studied by means of the emission channeling technique. Following 60 keV room-temperature implantation at a fluence of cm\!^{-2}, the angular distribution of \beta\!^{-}-particles emitted by the radioactive isotope Cu was measured by a position-sensitive detector. The - emission patterns give direct evidence that in the as-implanted state a large fraction of Cu atoms (60--70%) occupy almost ideal substitutional Zn sites with root mean square (rms) displacements of 0.16--0.17 Ă
. However, following annealing at 600°C and above Cu was found to be located on sites that are characterized by large rms displacements (0.3--0.5 Ă
) from Zn sites
Lattice location and thermal stability of implanted Fe in ZnO
The emission channeling technique was applied to evaluate the lattice location of implanted Fe in single-crystalline ZnO. The angular distribution of - particles emitted by Fe was monitored with a position-sensitive electron detector, following 60-keV low dose ( cm) room-temperature implantation of the precursor isotope Mn. The emission patterns around the [0001], [1102], [1101] and [2113] directions revealed that following annealing at 800°C 95(8)% of the Fe atoms occupy ideal substitutional Zn sites with root mean square displacements of 0.06-0.09 Ă
State space c-reductions for concurrent systems in rewriting logic
We present c-reductions, a state space reduction technique.
The rough idea is to exploit some equivalence relation on states (possibly capturing system regularities) that preserves behavioral properties, and explore the induced quotient system. This is done by means of a canonizer
function, which maps each state into a (non necessarily unique) canonical representative of its equivalence class. The approach exploits the expressiveness of rewriting logic and its realization in Maude to enjoy several advantages over similar approaches: exibility and simplicity in
the definition of the reductions (supporting not only traditional symmetry reductions, but also name reuse and name abstraction); reasoning support for checking and proving correctness of the reductions; and automatization
of the reduction infrastructure via Maude's meta-programming
features. The approach has been validated over a set of representative case studies, exhibiting comparable results with respect to other tools
Biologische Kontrolle von Eulenraupen im Kohl mittels Baculoviren
Baculoviren sind als hoch selektive biologische Kontrollagenzien fĂŒr Kohleulenraupen (Mamestra brassicae) seit lĂ€ngerem bekannt und ihre gute Wirksamkeit wurde schon in verschiedenen GewĂ€chshaus- und Freilandversuchen nachgewiesen. Um die Kontrollsituation von Kohleulenraupen im ökologischen GemĂŒseanbau insbesondere bei niedrigen Temperaturen zu verbessern, wurden die eulenpathogenen Mamestra brassicae Nukelopolyhedrovirus (MbMNPV) und Mamestra configurata Nukleopolyhedrovirus (MacoNPV-A) als mögliche Kontrollagentien geprĂŒft. Es konnte gezeigt werden, dass auch MacoNPV-A fĂŒr M.brassicae pathogen ist. In vergleichenden Bioassays bei 24°C zeigten MbMNPV und MacoNPV-A keinen signifikanten Unterschied hinsichtlich ihrer biologischen AktivitĂ€t gegenĂŒber M.brassicae. In weiteren Bioassays wurden die konzentrationsabhĂ€ngige MortalitĂ€t von M.brassicae im 2. Larvenstadium sowie die gefressene BlattflĂ€che bei 24, 20, 16 und 12°C bestimmt. Im Vergleich zu 24 und 20°C waren die mittleren Letalkonzentrationen bei 16 und 12°C 100 bzw. 1000fach höher. FĂŒr eine mittlere Reduktion der konsumierten BlattflĂ€che waren hingegen bei Temperaturen unter 20°C 10 bis 100fach höhere Konzentrationen notwendig. Durch die Neuformulierung von MbMNPV (Probis GmbH, Wiernsheim) konnte eine Wirkungssteigerung im Vergleich zu der nicht formulierten Virussuspension im Bioassay erzielt werden. In einem Freilandtest mit kĂŒnstlicher Infestation in Kohlrabi konnte eine weitere Steigerung des Wirkungsgrades durch die Kombination mit dem Bacillus thuringiensis PrĂ€parat XenTariÂź im Vergleich zur Einzelapplikation der beiden PrĂ€parate erreicht werden. Eine breite Freilandtestung der Baculoviren-PrĂ€paraten gegen Kohlraupen bei kĂŒhler Witterung als EinzelprĂ€parat und in Kombination mit Bacillus thuringiensis PrĂ€paraten sowie neuester Applikationstechnik fĂŒr Ober- und Unterblattbehandlung wird empfohlen
Lattice sites of implanted Cu and Ag in ZnO
The group b impurities Cu and Ag on substitutional Zn sites are among possible candidates for p-type doping of ZnO. In order to explore possible lattice sites of Cu and Ag in ZnO the radioactive impurities Cu and Ag were implanted at doses of cmcm at 60 keV into ZnO single crystals. The emission channeling effects of \beta\!^{-} -particles from the decay were studied by means of position-sensitive electron detectors, giving direct evidence that in the as-implanted state large fractions of Cu and Ag atoms (60--70% for Cu and 30% for Ag) occupy almost ideal substitutional Zn sites with root mean square (rms) displacements of 0.014--0.017 nm. However, following vacuum annealing at 600 °C and above both Cu and Ag were found to be located increasingly on sites that are characterized by large rms displacements (0.03--0.05 nm) from Zn sites. We conclude that in high-temperature treated ZnO Cu and Ag are most likely not simply replacing Zn atoms but are incorporated in complexes with other crystal defects or as clusters
Cooperation and Self-Regulation in a Model of Agents Playing Different Games
A simple model for cooperation between "selfish" agents, which play an
extended version of the Prisoner's Dilemma(PD) game, in which they use
arbitrary payoffs, is presented and studied. A continuous variable,
representing the probability of cooperation, [0,1], is assigned to
each agent at time . At each time step a pair of agents, chosen at
random, interact by playing the game. The players update their using a
criteria based on the comparison of their utilities with the simplest estimate
for expected income. The agents have no memory and use strategies not based on
direct reciprocity nor 'tags'. Depending on the payoff matrix, the systems
self-organizes - after a transient - into stationary states characterized by
their average probability of cooperation and average equilibrium
per-capita-income . It turns out that the model
exhibit some results that contradict the intuition. In particular, some games
which - {\it a priory}- seems to favor defection most, may produce a relatively
high degree of cooperation. Conversely, other games, which one would bet that
lead to maximum cooperation, indeed are not the optimal for producing
cooperation.Comment: 11 pages, 3 figures, keybords: Complex adaptive systems, Agent-based
models, Social system
Deformed two center shell model
A highly specialized two-center shell model has been developed accounting for
the splitting of a deformed parent nucleus into two ellipsoidaly deformed
fragments. The potential is based on deformed oscillator wells in direct
correspondance with the shape change of the nuclear system. For the first time
a potential responsible for the necking part between the fragments is
introduced on potential theory basis. As a direct consequence, spin-orbit {\bf
ls} and {\bf l} operators are calculated as shape dependent. Level scheme
evolution along the fission path for pairs of ellipsoidaly deformed fragments
is calculated. The Strutinsky method yields the shell corrections for different
mass asymmetries from the superheavy nucleus 122 and Cf all
along the splitting process.Comment: 32 pages, 8 figure
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