64,760 research outputs found
Probing the Geometry of Supernovae with Spectropolarimetry
We present results from a spectropolarimetric survey of young supernovae
completed at the Keck Observatory, including at least one example from each of
the major supernova types: Ia (1997dt), Ib (1998T, 1997dq), Ib/c-pec (1997ef),
IIn (1997eg), and II-P (1997ds). All objects show evidence for intrinsic
polarization, suggesting that asphericity may be a common feature in young
supernova atmospheres.Comment: 4 pages, 2 figures. To appear in the Proceedings of the 10th Annual
October Astrophysics Conference in Maryland: Cosmic Explosion
Reliable and robust molecular sexing of the hen harrier (Circus cyaneus) using PCR-RFLP of the CHD1 gene
The hen harrier (Circus cyaneus) is a bird of prey that is persecuted in the United Kingdom, and there is a need for a DNA-based individual identification and sexing system for the use in forensic investigations. This study reports a new set of PCR primers for the chromo-helicase-DNA-binding protein 1 gene, which allows sexing using PCR-RFLP. Instead of exonic primers that amplify across a large intron, this set consists of a primer within the intron, enabling reduction in amplicon sizes from 356 to 212 bp and 565 to 219 bp in W and Z chromosomes. DNA degradation and dilution experiments demonstrate that this set is significantly more robust than one that amplifies across the intron, and sequencing of the intronic primer-binding region across several individuals shows that it is highly conserved. While our objective is to incorporate this primer set into an STR-based individualization kit, it may in the meantime prove useful in forensic or conservation studies
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Preterm nutritional intake and MRI phenotype at term age: a prospective observational study
Objective:
To describe (1) the relationship between nutrition and the preterm-at-term infant phenotype, (2) phenotypic differences between preterm-at-term infants and healthy term born infants and (3) relationships between somatic and brain MRI outcomes.
Design:
Prospective observational study.
Setting:
UK tertiary neonatal unit.
Participants:
Preterm infants (<32â
weeks gestation) (n=22) and healthy term infants (n=39)
Main outcome measures:
Preterm nutrient intake; total and regional adipose tissue (AT) depot volumes; brain volume and proximal cerebral arterial vessel tortuosity (CAVT) in preterm infants and in term infants.
Results:
Preterm nutrition was deficient in protein and high in carbohydrate and fat. Preterm nutrition was not related to AT volumes, brain volume or proximal CAVT score; a positive association was noted between human milk intake and proximal CAVT score (r=0.44, p=0.05). In comparison to term infants, preterm infants had increased total adiposity, comparable brain volumes and reduced proximal CAVT scores. There was a significant negative correlation between deep subcutaneous abdominal AT volume and brain volume in preterm infants (r=â0.58, p=0.01).
Conclusions:
Though there are significant phenotypic differences between preterm infants at term and term infants, preterm macronutrient intake does not appear to be a determinant. Our preliminary data suggest that (1) human milk may exert a beneficial effect on cerebral arterial vessel tortuosity and (2) there is a negative correlation between adiposity and brain volume in preterm infants at term. Further work is warranted to see if our findings can be replicated and to understand the causal mechanisms
The high-field polar RX J1007.5-2017
We report optical and X-ray observations of the high-field polar
RXJ1007.5-2017 performed between 1990 and 2012. It has an orbital period of
208.60 min determined from the ellipsoidal modulation of the secondary star in
an extended low state. The spectral flux of the dM3- secondary star yields a
distance of 790+-105 pc. At low accretion levels, \RX{} exhibits pronounced
cyclotron emission lines. The second and third harmonic fall in the optical
regime and yield a field strength in the accretion spot of 94 MG. The source is
highly variable on a year-to-year basis and was encountered at visual
magnitudes between V \sim 20 and V \sim 16. In the intermediate state of 1992
and 2000, the soft X-ray luminosity exceeds the sum of the luminosities of the
cyclotron source, the hard X-ray source, and the accretion stream by an order
of magnitude. An X-ray high state, corresponding to the brightest optical
level, has apparently not been observed so far.Comment: To be published in A&
Large Scale Anisotropy of Cosmic Rays and Directional Neutrino Signals from Galactic Sources
We investigate the neutrino - cosmic ray connection for sources in the Galaxy
in terms of two observables: the shape of the energy spectrum and the
distribution of arrival directions. We also study the associated gamma ray
emission from these sources.Comment: Proceedings of the 2nd Cosmic Ray Anisotropy Workshop, 26-28
September 2013, Madison, Wisconsin. To appear in IOP Conference Serie
Direct experimental observation of binary agglomerates in complex plasmas
A defocusing imaging technique has been used as a diagnostic to identify
binary agglomerates (dimers) in complex plasmas. Quasi-two-dimensional plasma
crystal consisting of monodisperse spheres and binary agglomerates has been
created where the agglomerated particles levitate just below the spherical
particles without forming vertical pairs. Unlike spherical particles, the
defocused images of binary agglomerates show distinct, stationary/periodically
rotating interference fringe patterns. The results can be of fundamental
importance for future experiments on complex plasmas
Synchronization of particle motion in compressed two-dimensional plasma crystals
The collective motion of dust particles during the mode-coupling induced
melting of a two-dimensional plasma crystal is explored in molecular dynamics
simulations. The crystal is compressed horizontally by an anisotropic
confinement. This compression leads to an asymmetric triggering of the
mode-coupling instability which is accompanied by alternating chains of
in-phase and anti-phase oscillating particles. A new order parameter is
proposed to quantify the synchronization with respect to different directions
of the crystal. Depending on the orientation of the confinement anisotropy,
mode-coupling instability and synchronized motion are observed in one or two
directions. Notably, the synchronization is found to be direction-dependent.
The good agreement with experiments suggests that the confinement anisotropy
can be used to explain the observed synchronization process.Comment: 6 pages, 4 figure
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