684 research outputs found
Multi-frequency scatter broadening evolution of pulsars - II. Scatter broadening of nearby pulsars
We present multi-frequency scatter broadening evolution of 29 pulsars
observed with the LOw Frequency ARray (LOFAR) and Long Wavelength Array (LWA).
We conducted new observations using LOFAR Low Band Antennae (LBA) as well as
utilized the archival data from LOFAR and LWA. This study has increased the
total of all multi-frequency or wide-band scattering measurements up to a
dispersion measure (DM) of 150~pc\,cm by 60\%. The scatter broadening
timescale () measurements at different frequencies are often
combined by scaling them to a common reference frequency of 1\,GHz. Using our
data, we show that the --DM variations are best fitted for reference
frequencies close to 200--300\,MHz, and scaling to higher or lower frequencies
results in significantly more scatter in data. We suggest that this effect
might indicate a frequency dependence of the scatter broadening scaling index
(). However, a selection bias due to our chosen observing frequencies
can not be ruled out with the current data set. Our data did not favour any
particular model of the DM -- relations, and we do not see a
statistically significant break at the low DM range in this relation. The
turbulence spectral index () is found to be steeper than that is
expected from a Kolmogorov spectrum. This indicates that the local ISM
turbulence may have a low wave-number cutoff or presence of large scale
inhomogeneities in the line of sight to some of the reported pulsars.Comment: Accepted for publication in Ap
Review of the treatment of acute coronary syndrome in elderly patients
Advances in treatment and early revascularization have led to improved outcomes for patients with acute coronary syndrome (ACS). However, elderly ACS patients are less likely to receive evidence-based treatment, including revascularization therapy, due to uncertainty of the associated benefits and risks in this population. This article addresses key issues regarding medical and revascularization therapy in elderly ACS patients based on a review of the medical literature and in concordance with clinical practice guidelines from the American Heart Association (AHA) and the American College of Cardiology (ACC)
Lifting of the Landau level degeneracy in graphene devices in a tilted magnetic field
We report on transport and capacitance measurements of graphene devices in
magnetic fields up to 30 T. In both techniques, we observe the full splitting
of Landau levels and we employ tilted field experiments to address the origin
of the observed broken symmetry states. In the lowest energy level, the spin
degeneracy is removed at filling factors and we observe an enhanced
energy gap. In the higher levels, the valley degeneracy is removed at odd
filling factors while spin polarized states are formed at even . Although
the observation of odd filling factors in the higher levels points towards the
spontaneous origin of the splitting, we find that the main contribution to the
gap at , and is due to the Zeeman energy.Comment: 5 pages, 4 figure
Detection of radio emission from the gamma-ray pulsar J1732-3131 at 327 MHz
Although originally discovered as a radio-quiet gamma-ray pulsar, J1732-3131
has exhibited intriguing detections at decameter wavelengths. We report an
extensive follow-up of the pulsar at 327 MHz with the Ooty radio telescope.
Using the previously observed radio characteristics, and with an effective
integration time of 60 hrs, we present a detection of the pulsar at a
confidence level of 99.82%. The 327 MHz mean flux density is estimated to be
0.5-0.8 mJy, which establishes the pulsar to be a steep spectrum source and one
of the least-luminous pulsars known to date. We also phase-aligned the radio
and gamma-ray profiles of the pulsar, and measured the phase-offset between the
main peaks in the two profiles to be 0.240.06. We discuss the observed
phase-offset in the context of various trends exhibited by the radio-loud
gamma-ray pulsar population, and suggest that the gamma-ray emission from
J1732-3131 is best explained by outer magnetosphere models. Details of our
analysis leading to the pulsar detection, and measurements of various
parameters and their implications relevant to the pulsar's emission mechanism
are presented.Comment: 8 pages, 6 figures; Accepted for publication in MNRA
Accelerated Orthodontics
Clinical orthodontics is ever dynamic branch of Dentistry. Traditionally orthodontics was always considered as aesthetic treatment of face & also needed for proper oral oral function. This treatment may take up 2–3 years of total duration. The chapter describes changing trends in this aspect wherein we speed up the treatment by various methods thus reducing the overall time duration. These modalities include alteration in bio mechanics, pharmacological, chemical & by biological means. It is also cautioned here that the clinician has to take up these changing trends based on sound clinical knowledge & evidence based applicability
Full Genome Characterization of the Culicoides-Borne Marsupial Orbiviruses: Wallal Virus, Mudjinbarry Virus and Warrego Viruses
Viruses belonging to the species Wallal virus and Warrego virus of the genus Orbivirus were identified as causative agents of blindness in marsupials in Australia during 1994/5. Recent comparisons of nucleotide (nt) and amino acid (aa) sequences have provided a basis for the grouping and classification of orbivirus isolates. However, full-genome sequence data are not available for representatives of all Orbivirus species. We report full-genome sequence data for three additional orbiviruses: Wallal virus (WALV); Mudjinabarry virus (MUDV) and Warrego virus (WARV). Comparisons of conserved polymerase (Pol), sub-core-shell 'T2' and core-surface 'T13' proteins show that these viruses group with other Culicoides borne orbiviruses, clustering with Eubenangee virus (EUBV), another orbivirus infecting marsupials. WARV shares <70% aa identity in all three conserved proteins (Pol, T2 and T13) with other orbiviruses, consistent with its classification within a distinct Orbivirus species. Although WALV and MUDV share <72.86%/67.93% aa/nt identity with other orbiviruses in Pol, T2 and T13, they share >99%/90% aa/nt identities with each other (consistent with membership of the same virus species - Wallal virus). However, WALV and MUDV share <68% aa identity in their larger outer capsid protein VP2(OC1), consistent with membership of different serotypes within the species - WALV-1 and WALV-2 respectively
Transport and thermoelectric properties of the LaAlO/SrTiO interface
The transport and thermoelectric properties of the interface between
SrTiO and a 26-monolayer thick LaAlO-layer grown at high
oxygen-pressure have been investigated at temperatures from 4.2 K to 100 K and
in magnetic fields up to 18 T. For 4.2 K, two different electron-like
charge carriers originating from two electron channels which contribute to
transport are observed. We probe the contributions of a degenerate and a
non-degenerate band to the thermoelectric power and develop a consistent model
to describe the temperature dependence of the thermoelectric tensor. Anomalies
in the data point to an additional magnetic field dependent scattering.Comment: 7 pages, 4 figure
Scaling of the quantum-Hall plateau-plateau transition in graphene
The temperature dependence of the magneto-conductivity in graphene shows that
the widths of the longitudinal conductivity peaks, for the N=1 Landau level of
electrons and holes, display a power-law behavior following with a scaling exponent . Similarly the
maximum derivative of the quantum Hall plateau transitions
scales as with a scaling exponent
for both the first and second electron and hole Landau
level. These results confirm the universality of a critical scaling exponent.
In the zeroth Landau level, however, the width and derivative are essentially
temperature independent, which we explain by a temperature independent
intrinsic length that obscures the expected universal scaling behavior of the
zeroth Landau level
Gap opening in the zeroth Landau level of graphene
We have measured a strong increase of the low-temperature resistivity
and a zero-value plateau in the Hall conductivity at
the charge neutrality point in graphene subjected to high magnetic fields up to
30 T. We explain our results by a simple model involving a field dependent
splitting of the lowest Landau level of the order of a few Kelvin, as extracted
from activated transport measurements. The model reproduces both the increase
in and the anomalous plateau in in terms of
coexisting electrons and holes in the same spin-split zero-energy Landau level.Comment: 4 pages, 3 figure
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