275 research outputs found
Kinetics of Deposition of Oriented Superdisks
We use numerical Monte Carlo simulation to study kinetics of deposition of
oriented superdisks, bounded by the Lame curves of the form
, on regular planar substrate. It was recently shown that
the maximum packing density, as well as jamming density , exhibit
discontinuous derivative at , when the shape changes from convex to
concave form. By careful examination of the late-stage approach to the jamming
limit, we find that the leading term in temporal development is also
nonanalytic at , and offer heuristic excluded-area arguments for this
behavior
Vortex Bubble Formation in Pair Plasmas
It is shown that delocalized vortex solitons in relativistic pair plasmas
with small temperature asymmetries can be unstable for intermediate intensities
of the background electromagnetic field. Instability leads to the generation of
ever-expanding cavitating bubbles in which the electromagnetic fields are zero.
The existence of such electromagnetic bubbles is demonstrated by qualitative
arguments based on a hydrodynamic analogy, and by numerical solutions of the
appropriate Nonlinear Schr\"odinger equation with a saturating nonlinearity.Comment: 4 pages of two-column text, 2 figure
Stable topological modes in two-dimensional Ginzburg-Landau models with trapping potentials
Complex Ginzburg-Landau (CGL) models of laser media (with the cubic-quintic
nonlinearity) do not contain an effective diffusion term, which makes all
vortex solitons unstable in these models. Recently, it has been demonstrated
that the addition of a two-dimensional periodic potential, which may be induced
by a transverse grating in the laser cavity, to the CGL equation stabilizes
compound (four-peak) vortices, but the most fundamental "crater-shaped"
vortices (CSVs), alias vortex rings, which are, essentially, squeezed into a
single cell of the potential, have not been found before in a stable form. In
this work we report families of stable compact CSVs with vorticity S=1 in the
CGL model with the external potential of two different types: an axisymmetric
parabolic trap, and the periodic potential. In both cases, we identify
stability region for the CSVs and for the fundamental solitons (S=0). Those
CSVs which are unstable in the axisymmetric potential break up into robust
dipoles. All the vortices with S=2 are unstable, splitting into tripoles.
Stability regions for the dipoles and tripoles are identified too. The periodic
potential cannot stabilize CSVs with S>=2 either; instead, families of stable
compact square-shaped quadrupoles are found
Carcass characteristics and meat quality of broilers fed on earthworm (Lumbricus rubellus) meal
ΔΕΝ ΔΙΑΤΙΘΕΤΑΙ ΠΕΡΙΛΗΨΗThe aim of the research was to evaluate the carcass characteristics and meat quality from chickens fed on diets in which fish meal was substituted with raw earthworms (Lumbricus rubellus) or earthworm meal. In the trial which lasted 42-days, 100 one-day-old Hybro broilers were divided into the control and three experimental groups. The control group was fed on standard broiler feed, the first (E-I) and the second experimental groups (E-II) were fed a diet in which 50% or 100% of fish meal was substituted with earthworm meal, respectively, whilst the third group (E-III) consumed feed without fish meal, but was given raw chopped earthworms ad libitum from day 1 to day 42. The replacement of fish meal with fresh earthworms resulted in significantly lower carcass weights in the E-III group in comparison with the control group (p<0.05). The differences in drumstick, thigh and breast meat share relative to the carcass mass were not significant (p>0.05). The lowest fat content in thigh and breast meat was in the group in which fish meal was replaced with earthworm meal. The lightness (L*) of thigh and breast meat was highest in the broilers fed fresh earthworms ad libitum. No significant differences in pH value were detected between the experimental groups (p>0.05). The most consumer acceptable were drumstick samples from E-II group and the least acceptable samples from the control group. Earthworm meal may be considered an adequate substitute for fish meal in broiler chickens’ diet since it does not impair the production performance, carcass yield and meat quality
Far infrared properties of sintered PbTe doped with boron
Far infrared spectra of sintered PbTe doped with boron were analyzed. The measured infrared spectra were fated using a modified plasmon-phonnon interaction model with two additional oscillators (at about 195 cm(-1) and 285 cm(-1)) representing local B-impurity modes. The obtained results were compared with previously published data for a single crystal PbTe sample doped with boron
Measurement of the Crab Nebula spectrum over three decades in energy with the MAGIC telescopes
The MAGIC stereoscopic system collected 69 hours of Crab Nebula data between
October 2009 and April 2011. Analysis of this data sample using the latest
improvements in the MAGIC stereoscopic software provided an unprecedented
precision of spectral and night-by-night light curve determination at gamma
rays. We derived a differential spectrum with a single instrument from 50 GeV
up to almost 30 TeV with 5 bins per energy decade. At low energies, MAGIC
results, combined with Fermi-LAT data, show a flat and broad Inverse Compton
peak. The overall fit to the data between 1 GeV and 30 TeV is not well
described by a log-parabola function. We find that a modified log-parabola
function with an exponent of 2.5 instead of 2 provides a good description of
the data (). Using systematic uncertainties of red the MAGIC and
Fermi-LAT measurements we determine the position of the Inverse Compton peak to
be at (53 3stat + 31syst -13syst) GeV, which is the most precise
estimation up to date and is dominated by the systematic effects. There is no
hint of the integral flux variability on daily scales at energies above 300 GeV
when systematic uncertainties are included in the flux measurement. We consider
three state- of-the-art theoretical models to describe the overall spectral
energy distribution of the Crab Nebula. The constant B-field model cannot
satisfactorily reproduce the VHE spectral measurements presented in this work,
having particular difficulty reproducing the broadness of the observed IC peak.
Most probably this implies that the assumption of the homogeneity of the
magnetic field inside the nebula is incorrect. On the other hand, the
time-dependent 1D spectral model provides a good fit of the new VHE results
when considering a 80 {\mu}G magnetic field. However, it fails to match the
data when including the morphology of the nebula at lower wavelengths.Comment: accepted by JHEAp, 9 pages, 6 figure
Detection of bridge emission above 50 GeV from the Crab pulsar with the MAGIC telescopes
The Crab pulsar is the only astronomical pulsed source detected at very high
energy (VHE, E>100GeV) gamma-rays. The emission mechanism of VHE pulsation is
not yet fully understood, although several theoretical models have been
proposed. In order to test the new models, we measured the light curve and the
spectra of the Crab pulsar with high precision by means of deep observations.
We analyzed 135 hours of selected MAGIC data taken between 2009 and 2013 in
stereoscopic mode. In order to discuss the spectral shape in connection with
lower energies, 4.6 years of {\it Fermi}-LAT data were also analyzed. The known
two pulses per period were detected with a significance of and
. In addition, significant emission was found between the two
pulses with . We discovered the bridge emission above 50 GeV
between the two main pulses. This emission can not be explained with the
existing theories. These data can be used for testing new theoretical models.Comment: 5 pages, 4 figure
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