7,243 research outputs found
Interpreting the time variable RM observed in the core region of the TeV blazar Mrk 421
In this work we interpret and discuss the time variable rotation measure (RM)
found, for the first time over a 1-yr period, in the core region of a blazar.
These results are based on a one-year, multi-frequency (15, 24, and 43 GHz)
Very Long Baseline Array (VLBA) monitoring of the TeV blazar Markarian 421 (Mrk
421). We investigate the Faraday screen properties and its location with
respect to the jet emitting region. Given that the 43 GHz radio core flux
density and the RM time evolution suggest a similar trend, we explore the
possible connection between the RM and the accretion rate. Among the various
scenarios that we explore, the jet sheath is the most promising candidate for
being the main source of Faraday rotation. During the one-year observing period
the RM trend shows two sign reversals, which may be qualitatively interpreted
within the context of the magnetic tower models. We invoke the presence of two
nested helical magnetic fields in the relativistic jet with opposite
helicities, whose relative contribution produce the observed RM values. The
inner helical field has the poloidal component () oriented in the
observer's direction and produces a positive RM, while the outer helical field,
with in the opposite direction, produces a negative RM. We assume
that the external helical field dominates the contribution to the observed RM,
while the internal helical field dominates when a jet perturbation arises
during the second observing epoch. Being the intrinsic polarization angle
parallel to the jet axis, a pitch angle of the helical magnetic field
is required. Additional scenarios are also considered to
explain the observed RM sign reversals.Comment: 6 pages, 2 figures. Published on MNRA
Risk factors associated with sudden death vs. congestive heart failure or arterial thromboembolism in cats with hypertrophic cardiomyopathy
Release experiments with Octopus vulgaris Cuvier, 1797 in Galicia, NW Spain. First results on recapture rate, distribution and growth.
This paper describes the release experiments carried out with 465 octopus (Octopus vulgaris Cuvier, 1797) with an average weight ranging from 703 to 986 g in three different areas in the Ría of Vigo, Galicia, NW Spain. Thirty-seven individuals were recaptured by fishermen, representing a total recapture rate of 7.9 %. Among these, 80.5 % remained within 5 km of the release point, showing a sedentary behavior. The specific growth rate (SGR) in weight was 0.00902 ± 0.00468; there was not a significant difference between males and females. The exponential growth curve is the best fitting theoretical model. Life expectancy in Ría de Vigo waters was estimated at 18 months for males, and 16 months for females. Throughout the recapture process, males were predominant over females, giving a sex ratio of 1.83:1. Data reported in this paper on recapture rate, sedentary behavior and instantaneous growth rate can be used as reference for future stocking programs in Galicia
Culture viability of Sarddina pilchardus: preliminary results of growth in captivity
Larvae
of
Sardina
pilchardus
were
obtained
in
captivity
from
fertilized
eggs
captured
in
the
wild,
and
grown
in
a
10
000
L
tank.
Isochrysis
galbana
,
Artemia
franciscana
nauplii
and
live
zooplankton
were
used
as
prey
during
the
first
two
weeks;
afterwards,
anim
als
were
fed
on
artemia
metanauplius
enriched
with
Isochrysis
galbana
.
A
dry
feed
(Gemma
0.4
and
0.8)
from
SKRETTING
S.A.
(Burgos,
España)
was
supplied
from
the
third
to
18th
month.
The
total
length
reached
by
sardines
at
one
year
of
life
was
162.02
±
9.
49
mm,
corresponding
to
a
wet
weight
of
36.12
±
10.82
g.
Total
length
at
18
months
was
182.37
mm.
A
long
experiment
(18
‐
month)
of
sardine
culture
is
described
for
the
first
time,
and
growth
data
reported
can
contribute
to
determine
its
potential
interest
as
a
candidate
for
marine
aquacultur
Culture viability of Sardine pilchardus (Fish, teleost): Preliminary results of growth in captivity up to 18 months
Larvae of Sardina pilchardus were obtained in captivity from fertilized eggs captured in the wild and grown in a 10000-L tank. Isochrysis galbana, Artemia franciscana nauplii and live zooplankton were used as prey during the first two weeks; afterwards, the animals were fed on Artemia metanauplii enriched with Isochrysis galbana. A dry feed (Gemma 0.4 and 0.8) from Skretting S.A. (Burgos, España) was supplied from the 3rd to the 18th month. The total length reached by sardines at one year of life was 162.02±9.49 mm, corresponding to a wet weight of 36.12±10.82 g. Total length of the last survivor individual at 18 months was 182.37 mm. An 18-month experiment of sardine culture is described for the first time, and the growth data reported can help to determine its potential as a candidate for marine aquaculture.Publicado
Management of incidentally detected heart murmurs in dogs and cats
A dog or a cat has an incidentally detected heart murmur if the murmur is an unexpected discovery during a veterinary consultation that was not initially focused on the cardiovascular system. This document presents approaches for managing dogs and cats that have incidentally-detected heart murmurs, with an emphasis on murmur characteristics, signalment profiling, and multifactorial decision-making to choose an optimal course for a given patient
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