6,486 research outputs found
The radio structure of 3C 316, a galaxy with double-peaked narrow optical emission lines
The galaxy 3C\,316 is the brightest in the radio band among the
optically-selected candidates exhibiting double-peaked narrow optical emission
lines. Observations with the Very Large Array (VLA), Multi-Element Remotely
Linked Interferometer Network (e-MERLIN), and the European VLBI Network (EVN)
at 5\,GHz have been used to study the radio structure of the source in order to
determine the nature of the nuclear components and to determine the presence of
radio cores. The e-MERLIN image of 3C 316 reveals a collimated coherent
east-west emission structure with a total extent of about 3 kpc. The EVN image
shows seven discrete compact knots on an S-shaped line. However, none of these
knots could be unambiguously identified as an AGN core. The observations
suggest that the majority of the radio structure belongs to a powerful radio
AGN, whose physical size and radio spectrum classify it as a compact
steep-spectrum source. Given the complex radio structure with radio blobs and
knots, the possibility of a kpc-separation dual AGN cannot be excluded if the
secondary is either a naked core or radio quiet.Comment: 12 pages, 3 figures, 2 tables. Accepted for publication in the MNRA
Eight new MSPs in NGC 6440 and NGC 6441
We report the discovery of five new millisecond pulsars in the globular
cluster NGC 6440 and three new ones in NGC 6441; each cluster has one
previously known pulsar. Four of the new pulsars are found in binary systems.
One of the new pulsars, PSR J1748-2021B in NGC 6440, is notable for its
eccentric (e = 0.57) and wide (P_b = 20.5 days) orbit. If the rate of advance
of periastron is due solely to general relativity, we can estimate of the total
mass of this binary system: 2.92 +/- 0.20 solar masses. This would imply an
anomalously large mass for this pulsar, which could introduce important
constraints in the study of the equation of state for cold neutron matter.Comment: 3 pages, 3 figures. To appear in the proceedings of "40 Years of
Pulsars: Millisecond Pulsars, Magnetars, and More", August 12-17, 2007,
McGill University, Montreal, Canad
Dynamics of folding in Semiflexible filaments
We investigate the dynamics of a single semiflexible filament, under the
action of a compressing force, using numerical simulations and scaling
arguments. The force is applied along the end to end vector at one extremity of
the filament, while the other end is held fixed. We find that, unlike in
elastic rods the filament folds asymmetrically with a folding length which
depends only on the bending stiffness and the applied force. It is shown that
this behavior can be attributed to the exponentially falling tension profile in
the filament. While the folding time depends on the initial configuration, at
late time, the distance moved by the terminal point of the filament and the
length of the fold shows a power law dependence on time with an exponent 1/2.Comment: 13 pages, Late
VSOP observation of the quasar PKS 2215+020: a new laboratory for core-jet physics at z=3.572
We report results of a VSOP (VLBI Space Observatory Programme) observation of
a high redshift quasar PKS 2215+020 (z=3.572). The ~1 milliarcsecond resolution
image of the quasar reveals a prominent `core-jet' structure on linear scales
from 5/h to 300/h pc ($H_0=100*h km/(s*Mpc). The brightness temperatures and
sizes of bright features identified in the jet are consistent with emission
from relativistic shocks dominated by adiabatic energy losses. The jet is
powered by the central black hole with estimated mass of ~4*10^9 solar masses.
Comparisons with VLA and ROSAT observations indicate a possible presence of an
extended radio/X-ray halo surrounding 2215+020.Comment: 15 pages, 6 figures, aastex macros; accepted for publication in The
Astrophysical Journal, V.546, N.2 *(January 10 2001
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Extended magnetic reconnection across the dayside magnetopause
The extent of where magnetic reconnection (MR), the dominant process responsible for energy and plasma transport into the magnetosphere, operates across Earth’s dayside magnetopause has previously been only indirectly shown by observations. We report the first direct evidence of X-line structure resulting from the operation of MR at each of two widely separated locations along the tilted, subsolar line of maximum current on Earth’s magnetopause, confirming the operation of MR at two or more sites across the extended region where MR is expected to occur. The evidence results from in-situ observations of the associated ion and electron plasma distributions, present within each magnetic X-line structure, taken by two spacecraft passing through the active MR regions simultaneously
Symmetries and Fixed Point Stability of Stochastic Differential Equations Modeling Self-Organized Criticality
A stochastic nonlinear partial differential equation is built for two
different models exhibiting self-organized criticality, the Bak, Tang, and
Wiesenfeld (BTW) sandpile model and the Zhang's model. The dynamic
renormalization group (DRG) enables to compute the critical exponents. However,
the nontrivial stable fixed point of the DRG transformation is unreachable for
the original parameters of the models. We introduce an alternative
regularization of the step function involved in the threshold condition, which
breaks the symmetry of the BTW model. Although the symmetry properties of the
two models are different, it is shown that they both belong to the same
universality class. In this case the DRG procedure leads to a symmetric
behavior for both models, restoring the broken symmetry, and makes accessible
the nontrivial fixed point. This technique could also be applied to other
problems with threshold dynamics.Comment: 19 pages, RevTex, includes 6 PostScript figures, Phys. Rev. E (March
97?
Effect of oral administration of protected DL- methionine on wool quality and production of pregnant Merino hoggets raised in the argentinian Patagonia
Little is known about the effect of protected methionine supplemented to grazing pregnant ewes. In the present trial, oral administration of protected DL- methionine was tested in terms of: mean fibre diameter (MFD), growth of fibre length (L), unwashed fleece weight (UFW) and staple strength (SS) in pregnant hoggets grazing Patagonian ranges. The relationship between the coeficient of variation of MFD (CVMFD) and (SS) was also established. One hundred Merino hoggets were allotted at random to ten groups of ten animals each. Individual groups were the experimental unit. Five groups were supplemented with protected DL-methionine (PM) at 2.5 g.animal-1.day-1, the rest were control (C). Mean fibre diameter was measured in samples from the shoulder region. The “dye banding” technique was used to assess L. Data were analyzed according to a lineal model. Differences for UFW were significant (p<0.05) (2.70 ± 0.13 kg and 3.00 ± 0.17 kg for C and PM respectively) as well as for L, 0.84 ± 0.06 mm for C and 1.07 ± 0.04 mm for PM. Neither differences for SS (p>0.05) nor for CVMFD were significative, values for the latter ranged from 17 to 19 %. Supplementation with protected DL-methionine allowed to improve production parameters, therefore it is a technique worthwhile considering when feeding pregnant hoggets grazing rangelands
BLASTPLOT: a PERL module to plot next generation sequencing NCBI-BLAST results
BACKGROUND: The development of Next Generation Sequencing (NGS) during the last decade has created an unprecedented amount of sequencing data, as well as the ability to rapidly sequence specimens of interest. Read-based BLAST analysis of NGS data is a common procedure especially in the case of metagenomic samples. However, coverage is usually not enough to allow for de novo assembly. This type of read-based analysis often creates the question of how the reads that align to the same sequence are distributed. The same question applies to preparation of primers or probes for microarray experiments. Although there are several packages that allow the visualization of DNA segments in relation to a reference, in most cases they require the visualization of one reference at a time and the capture of screen shots for each segment. Such a procedure could be tedious and time consuming. The field is in need of a solution that automates the capture of coverage plots for all the segments of interest. RESULTS: We have created BLASTPLOT, a PERL module to quickly plot the BLAST results from short sequences (primers, probes, reads) against reference targets. CONCLUSIONS: BLASTPLOT is a simple to use PERL module that allows the generation of PNG graphs for all the reference sequences associated with a BLAST result set
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