5,393 research outputs found
The soft X-ray excess AGN RE J2248-511
We model the spectral energy distribution of the ultrasoft broad-line AGN RE
J2248-511 with Comptonised accretion disc models. These are able to reproduce
the steep optical and ultrasoft X-ray slopes, and the derived black hole mass
is consistent with independent mass estimates. This AGN displays properties of
both broad and narrow line Seyfert 1 galaxies, but we conclude that it is
intrinsically a `normal' Seyfert 1 viewed at high inclination angle.Comment: 4 pages, 1 figure. MG10 Proceeding
An Investigation of Unstructured Play in Nature and its Effect on Childrenâs Self-Efficacy
ABSTRACT
AN INVESTIGATION OF UNSTRUCTURED PLAY IN NATURE AND ITS EFFECT
ON CHILDRENâS SELF-EFFICACY
Paul Starling
Dr. Lani Nelson-Zlupko
Much attention is being given to childhood physical and mental well-being as it relates to outdoor play in nature. This is particularly relevant as todayâs children are spending much less time outdoors, and even less time in unstructured play compared to indoor time or highly regulated supervised activity. Recent research indicates that outdoor unstructured play may be essential to core mastery in children: it has been linked to improvements in cognitive, behavioral, and even physical functioning.
This study investigated whether unstructured play in nature had an effect on childrenâs self-efficacy. An original, mixed methods, empirical study was conducted which enlisted 21 subjects, (n=11 male) and (n=10 female) ages 8-12. These subjects took part in unstructured play in nature within a 3-week period of time while attending a summer camp. Subjects played anywhere from 2-5 days in 45-minute play sessions. Subjects completed the modified widely used Self-Efficacy Scale (SES) and the Emotional Self-Efficacy Scale (ESES) at pre and post conditions in order to explore whether or not exposure to unstructured outdoor play in nature contributes to increases in perceived self-efficacy. Quantitative results indicated no difference at post-test but when frequency of exposure to the experimental condition was factored in a lowering of self-efficacy as measured by the modified SES surfaced. Statistics also revealed that the exposure to the experimental condition alone was not significant enough to account for the decrease in self-efficacy scores. Qualitative field notes taken throughout the study indicated the contrary: there were indeed multiple instances of self-efficacy development
Repurposing the (super)crip: media representations of disability at the Rio 2016 Paralympic Games
Multiwavelength XMM-Newton observations of the Laor et al. sample of PG quasars
We present XMM-Newton/EPIC spectra for the Laor et al. sample of Palomar
Green quasars. We find that a power-law provides a reasonable fit to the 2-5
keV region of the spectra. Excess soft X-ray emission below 2 keV is present
for all objects, with the exception of those known to contain a warm absorber.
A single power-law is, however, a poor fit to the 0.3-10.0 keV spectrum and
instead we find that a simple model, consisting of a broken power-law (plus an
iron line), provides a reasonable fit in most cases. The equivalent width of
the emission line is constrained in just twelve objects but with low (<2 sigma)
significance in most cases. For the sources whose spectra are well-fit by the
broken power-law model, we find that various optical and X-ray line and
continuum parameters are well-correlated; in particular, the power-law photon
index is well-correlated with the FWHM of the Hbeta line and the photon indices
of the low and high energy components of the broken power-law are
well-correlated with each other. These results suggest that the 0.3-10 keV
X-ray emission shares a common (presumably non-thermal) origin, as opposed to
suggestions that the soft excess is directly produced by thermal disc emission
or via an additional spectral component. We present XMM-Newton/OM data which we
combine with the X-ray spectra so as to produce broad-band spectral energy
distributions, free from uncertainties due to long-term variability in
non-simultaneous data. Fitting these optical-UV spectra with a Comptonized disc
model indicates that the soft X-ray excess is independent of the accretion
disc, confirming our interpretation of the tight correlation between the hard
and soft X-ray spectra.Comment: Accepted for publication in MNRA
Swift captures the spectrally evolving prompt emission of GRB 070616
The origins of Gamma-ray Burst prompt emission are currently not well
understood and in this context long, well-observed events are particularly
important to study. We present the case of GRB 070616, analysing the
exceptionally long-duration multipeaked prompt emission, and later afterglow,
captured by all the instruments on-board Swift and by Suzaku WAM. The high
energy light curve remained generally flat for several hundred seconds before
going into a steep decline. Spectral evolution from hard to soft is clearly
taking place throughout the prompt emission, beginning at 285 s after the
trigger and extending to 1200 s. We track the movement of the spectral peak
energy, whilst observing a softening of the low energy spectral slope. The
steep decline in flux may be caused by a combination of this strong spectral
evolution and the curvature effect. We investigate origins for the spectral
evolution, ruling out a superposition of two power laws and considering instead
an additional component dominant during the late prompt emission. We also
discuss origins for the early optical emission and the physics of the
afterglow. The case of GRB 070616 clearly demonstrates that both broadband
coverage and good time resolution are crucial to pin down the origins of the
complex prompt emission in GRBs.Comment: 13 pages, 11 figures (2 in colour), MNRAS accepte
Gas and dust properties in the afterglow spectra of GRB 050730
We present early WHT ISIS optical spectroscopy of the afterglow of gamma-ray
burst GRB 050730. The spectrum shows a DLA system with the highest measured
hydrogen column to date: N(HI) = 22.1 +/- 0.1 at the third-highest GRB redshift
z = 3.968. Our analysis of the Swift XRT X-ray observations of the early
afterglow show X-ray flares accompanied by decreasing X-ray absorption. From
both the optical and the X-ray spectra we constrain the dust and gas properties
of the host galaxy. We find the host to be a low metallicity galaxy, with low
dust content. Much of the X-ray absorbing gas is situated close to the GRB,
whilst the HI absorption causing the DLA is most likely located further out.Comment: 5 pages, 2 figures. Accepted for A&A Letter
GRB060602B = Swift J1749.4-2807: an unusual transiently accreting neutron-star X-ray binary
We present an analysis of the Swift BAT and XRT data of GRB060602B, which is
most likely an accreting neutron star in a binary system and not a gamma-ray
burst. Our analysis shows that the BAT burst spectrum is consistent with a
thermonuclear flash (type-I X-ray burst) from the surface of an accreting
neutron star in a binary system. The X-ray binary nature is further confirmed
by the report of a detection of a faint point source at the position of the XRT
counterpart of the burst in archival XMM-Newton data approximately 6 years
before the burst and in more recent XMM-Newton data obtained at the end of
September 2006 (nearly 4 months after the burst). Since the source is very
likely not a gamma-ray burst, we rename the source Swift J1749.4-2807, based on
the Swift/BAT discovery coordinates. Using the BAT data of the type-I X-ray
burst we determined that the source is at most at a distance of 6.7+-1.3 kpc.
For a transiently accreting X-ray binary its soft X-ray behaviour is atypical:
its 2-10 keV X-ray luminosity (as measured using the Swift/XRT data) decreased
by nearly 3 orders of magnitude in about 1 day, much faster than what is
usually seen for X-ray transients. If the earlier phases of the outburst also
evolved this rapidly, then many similar systems might remain undiscovered
because the X-rays are difficult to detect and the type-I X-ray bursts might be
missed by all sky surveying instruments. This source might be part of a class
of very-fast transient low-mass X-ray binary systems of which there may be a
significant population in our Galaxy.Comment: Accepted for publication in MNRA
Chronic heart block in dogs; a method for producing experimental heart failure
A method is described for the production of chronic atrioventricular block in dogs, by incision of the region of the bundle of His through the open right atrium during temporary caval occlusion. Exercise tolerances, chest x-ray films, electrocardiograms, phonocardiograms, cardiac outputs, intracardiac pressures, femoral pressures, and left ventricular coronary flows were obtained preoperatively and from 1 to 10 months postoperatively. The majority of the animals developed clinical, laboratory, and pathological evidence of congestive heart failure. All animals had generalized myocardial hypertrophy
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