763 research outputs found
On decay of large amplitude bubble of disoriented chiral condensate
The time evolution of initially formed large amplitude bubble of disoriented
chiral condensate (DCC) is studied. It is found that the evolution of this
object may have a relatively long pre-decay stage. Simple explanation of such
delay of the DCC bubble decay is given. This delay is related to the existence
of the approximate solutions of multi-soliton type of the corresponding radial
sine-Gordon equation in (3+1) dimensions at large bubble radius.Comment: 6 pages, LaTeX, 5 PostScript figure
Refresher Training of teachers of Music in the System of Postgraduate Teachers’ Training
При финансовой поддержке Российского гуманитарного научного фонда, проект № 08-06-14135
Universality in a Class of Q-Ball Solutions: An Analytic Approach
The properties of Q-balls in the general case of a sixth order potential have
been studied using analytic methods. In particular, for a given potential, the
initial field value that leads to the soliton solution has been derived and the
corresponding energy and charge have been explicitly evaluated. The proposed
scheme is found to work reasonably well for all allowed values of the model
parameters.Comment: 9 Pages, 6 Figure
Metal-insulator transition induced by 16O -18O oxygen isotope exchange in colossal negative magnetoresistance manganites
The effect of 16O-18O isotope exchange on the electric resistivity was
studied for (La(1-y)Pr(y))0.7Ca0.3MnO3 ceramic samples. Depending on y, this
mixed perovskite exhibited different types of low-temperature behavior ranging
from ferromagnetic metal (FM) to charge ordered (CO) antiferromagnetic
insulator. It was found that at y=0.75, the substitution of 16O by 18O results
in the reversible transition from a FM to a CO insulator at zero magnetic
field. The applied magnetic field (H >= 2 T) transformed the sample with 18O
again to the metallic state and caused the increase in the FM transition
temperature Tc of the 16O sample. As a result, the isotope shift of Tc at H = 2
T was as high as 63 K. Such unique sensitivity of the system to oxygen isotope
exchange, giving rise even to the metal-insulator transition, is discussed in
terms of the isotope dependence of the effective electron bandwidth which
shifts the balance between the CO and FM phases.Comment: 5 pages (RevTeX), 2 eps figures included, to appear in J. Appl. Phys.
83, (1998
Історична ретроспектива розвитку сільськогосподарського дорадництва в Україні (1995–2015 рр.)
Реформи в сільському господарстві незалежної України породили велику кількість нових приватних власників і користувачів земельних угідь. Значна частина з них – фермери, власники особистих селянських господарств – мають недостатній рівень сільськогосподарських знань, зокрема щодо використання новітніх технологій у рослинництві та тваринництві. Тому вони потребують професійної допомоги, консультування і підвищення рівня сільськогосподарських знань. Такі послуги є елементами сільськогосподарського дорадництва, як окремого виду діяльності в сільському господарстві. Автором проаналізовані етапи становлення та розвитку сільськогосподарської дорадчої діяльності в Україні та запропоновані напрями її удосконалення
Kink-antikink interactions in the double sine-Gordon equation and the problem of resonance frequencies
We studied the kink-antikink collision process for the "double sine-Gordon"
(DSG) equation in 1+1 dimensions at different values of the potential parameter
. For small values of we discuss the problem of resonance frequencies.
We give qualitative explanation of the frequency shift in comparison with the
frequency of the discrete level in the potential well of isolated kink. We show
that in this region of the parameter the effective long-range interaction
between kink and antikink takes place.Comment: 9 pages, LaTeX, 4 figures (eps
The bubbles of matter from multiskyrmions
The multiskyrmions with large baryon number B given by rational map (RM)
ansaetze can be described reasonably well within the domain wall approximation,
or as spherical bubbles with energy and baryon number density concentrated at
their boundary. A special class of profile functions is considered
approximating the true profile and domain wall behaviour at the same time. An
upper bound is obtained for the masses of RM multiskyrmions which is close to
the calculated masses, especially at large B. The gap between rigorous upper
and lower bounds for large B multiskyrmions is less than 4%. The basic
properties of such bubbles of matter are investigated, some of them being of
universal character, i.e. they do not depend on baryon number of configuration
and on the number of flavors. As a result, the lagrangian of the Skyrme type
models provides field theoretical realization of the bag model of special kind.Comment: 7 pages, no figure
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