5,771 research outputs found
Finding the right title for your article: Advice for academic author.
On reading the title of an article the reader can sometimes wonder what the author is trying to say, as the title seems so far removed from the research covered in the article. Do such authors forget that many readers of health and medical journals browse the list of contents (in a paper or electronic format) and use titles to select the article that attracts attention? Academic authors are often not clear enough in the titles of their articles, and hence may not attract as large a readership as possible. Any author would want their article to be read and cited, and to stand out in a crowded Table of Contents or a list of papers found in a search on electronic databases.DOI: http://dx.doi.org/10.3126/nje.v4i1.10138 Nepal Journal of Epidemiology 2014;4 (1): 344-347</jats:p
The mid-infrared diameter of W Hydrae
Mid-infrared (8-13 microns) interferometric data of W Hya were obtained with
MIDI/VLTI between April 2007 and September 2009, covering nearly three
pulsation cycles. The spectrally dispersed visibility data of all 75
observations were analyzed by fitting a circular fully limb-darkened disk (FDD)
model to all data and individual pulsation phases. Asymmetries were studied
with an elliptical FDD. Modeling results in an apparent angular FDD diameter of
W Hya of about (80 +/- 1.2) mas (7.8 AU) between 8 and 10 microns, which
corresponds to an about 1.9 times larger diameter than the photospheric one.
The diameter gradually increases up to (105 +/- 1.2) mas (10.3 AU) at 12
microns. In contrast, the FDD relative flux fraction decreases from (0.85 +/-
0.02) to (0.77 +/- 0.02), reflecting the increased flux contribution from a
fully resolved surrounding silicate dust shell. The asymmetric character of the
extended structure could be confirmed. An elliptical FDD yields a position
angle of (11 +/- 20) deg and an axis ratio of (0.87 +/- 0.07). A weak pulsation
dependency is revealed with a diameter increase of (5.4 +/- 1.8) mas between
visual minimum and maximum, while detected cycle-to-cycle variations are
smaller. W Hya's diameter shows a behavior that is very similar to the Mira
stars RR Sco and S Ori and can be described by an analogous model. The constant
diameter part results from a partially resolved stellar disk, including a close
molecular layer of H2O, while the increase beyond 10 microns can most likely be
attributed to the contribution of a spatially resolved nearby Al2O3 dust shell.Comment: 18 pages, 16 figure
The Human Rights & Dignity Experience of Disabled Women during Pregnancy, Childbirth and Early Parenting
Discovery of spatial periodicities in a coronal loop using automated edge-tracking algorithms
A new method for automated coronal loop tracking, in both spatial and temporal domains, is presented. Applying this technique to TRACE data, obtained using the 171 Å filter on 1998 July 14, we detect a coronal loop undergoing a 270 s kink-mode oscillation, as previously found by Aschwanden et al. However, we also detect flare-induced, and previously unnoticed, spatial periodicities on a scale of 3500 km, which occur along the coronal loop edge. Furthermore, we establish a reduction in oscillatory power for these spatial periodicities of 45% over a 222 s interval. We relate the reduction in detected oscillatory power to the physical damping of these loop-top oscillations
bRing: An observatory dedicated to monitoring the Pictoris b Hill sphere transit
Aims. We describe the design and first light observations from the
Pictoris b Ring ("bRing") project. The primary goal is to detect photometric
variability from the young star Pictoris due to circumplanetary
material surrounding the directly imaged young extrasolar gas giant planet
\bpb. Methods. Over a nine month period centred on September 2017, the Hill
sphere of the planet will cross in front of the star, providing a unique
opportunity to directly probe the circumplanetary environment of a directly
imaged planet through photometric and spectroscopic variations. We have built
and installed the first of two bRing monitoring stations (one in South Africa
and the other in Australia) that will measure the flux of Pictoris,
with a photometric precision of over 5 minutes. Each station uses two
wide field cameras to cover the declination of the star at all elevations.
Detection of photometric fluctuations will trigger spectroscopic observations
with large aperture telescopes in order to determine the gas and dust
composition in a system at the end of the planet-forming era. Results. The
first three months of operation demonstrate that bRing can obtain better than
0.5\% photometry on Pictoris in five minutes and is sensitive to
nightly trends enabling the detection of any transiting material within the
Hill sphere of the exoplanet
On the origin of planets at very wide orbits from the re-capture of free floating planets
In recent years several planets have been discovered at wide orbits (>100 AU)
around their host stars. Theoretical studies encounter difficulties in
explaining their formation and origin. Here we propose a novel scenario for the
production of planetary systems at such orbits, through the dynamical recapture
of free floating planets (FFPs) in dispersing stellar clusters. This process is
a natural extension of the recently suggested scenario for the formation of
wide stellar binaries. We use N-body simulations of dispersing clusters with
10-1000 stars and comparable numbers of FFPs to study this process. We find
that planets are captured into wide orbits in the typical range ~100-10^6 AU,
and have a wide range of eccentricities (thermal distribution). Typically, 3-6
x (f_FFP/1) % of all stars capture a planetary companion with such properties
(where f_FFP is the number of FFP per star). The planetary capture efficiency
is comparable to that of capture-formed stellar-binaries, and shows a similar
dependence on the cluster size and structure. It is almost independent of the
specific planetary mass; planets as well as sub-stellar companions of any mass
can be captured. The capture efficiency decreases with increasing cluster size,
and for a given cluster size the it increases with the host/primary mass. More
than one planet can be captured around the same host and planets can be
captured into binary systems. Planets can also be captured into pre-existing
planetary and into orbits around black holes and massive white dwarfs, if these
formed early enough before the cluster dispersal. In particular, stellar black
holes have a high capture efficiency (>50 % and 5-10 x (f_FFP/1) % for capture
of stars and planetary companions, respectively) due to their large mass.
Finally, although rare, two FFPs or brown dwarfs can become bound and form a
FFP-binary system with no stellar host.Comment: ApJ, in press. Added two figure
Long-Baseline Interferometric Multiplicity Survey of the Sco-Cen OB Association
We present the first multiplicity-dedicated long baseline optical
interferometric survey of the Scorpius-Centaurus-Lupus-Crux association. We
used the Sydney University Stellar Interferometer to undertake a survey for new
companions to 58 Sco-Cen B- type stars and have detected 24 companions at
separations ranging from 7-130mas, 14 of which are new detections. Furthermore,
we use a Bayesian analysis and all available information in the literature to
determine the multiplicity distribution of the 58 stars in our sample, showing
that the companion frequency is F = 1.35 and the mass ratio distribution is
best described as a power law with exponent equal to -0.46, agreeing with
previous Sco-Cen high mass work and differing significantly from lower-mass
stars in Tau-Aur. Based on our analysis, we estimate that among young B-type
stars in moving groups, up to 23% are apparently single stars. This has strong
implications for the understanding of high-mass star formation, which requires
angular momentum dispersal through some mechanism such as formation of multiple
systems.Comment: 7 figures, 5 tables, accepted for publication in MNRA
Entanglement of arbitrary superpositions of modes within two-dimensional orbital angular momentum state spaces
We use spatial light modulators (SLMs) to measure correlations between arbitrary superpositions of orbital angular momentum (OAM) states generated by spontaneous parametric down-conversion. Our technique allows us to fully access a two-dimensional OAM subspace described by a Bloch sphere, within the higher-dimensional OAM Hilbert space. We quantify the entanglement through violations of a Bell-type inequality for pairs of modal superpositions that lie on equatorial, polar, and arbitrary great circles of the Bloch sphere. Our work shows that SLMs can be used to measure arbitrary spatial states with a fidelity sufficient for appropriate quantum information processing systems
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