21,595 research outputs found
The Surveyor 5, 6, and 7 Flight Paths and Their Determination from Tracking Data
Surveyor 5, 6, and 7 flight paths and tracking data for space station location
An exploratory randomised controlled trial comparing the effectiveness of different duration of canine-assisted interventions in higher education students
The aim of this study was to explore whether different durations of canine-assisted intervention (CAI) influenced the beneficial effects of CAI on anxiety, stress, depression, and the well-being of higher education (HE) students. Eighty-eight participants took part in an exploratory randomised control trial (RCT) and were assigned to the 2, 5, and 10-min CAI groups who interacted with a canine, or a control group who watched an unrelated slideshow. Pre- and post-intervention anxiety, stress, depression, and well-being levels were measured. Additionally, the type of interaction between humans and canines was recorded as well as participantsâ views of the caninesâ neoteny (juvenile features) to explore whether interaction activity and canine features have an impact on the beneficial positive effects of CAI. The results showed no differences in the duration of CAI in reducing anxiety, stress, and depression, meaning a 2-min CAI session was as effective as a 10-min session. The results also found individual intervention activities between humans and canines did not predict a reduction in anxiety, stress, depression, or an increase in general well-being. Additionally, a negative correlation was found between the cuteness of the canine and anxiety, and between the cuddliness of the canine and stress, although these results should be interpreted with caution due to high canine trait scores. Overall, this study used a CAI and control group to explore the differences between a single 2, 5, and 10-min CAI sessions in HE students and demonstrated a 2-min CAI session was as effective as a longer 10-min CAI session in supporting the mental health of HE students, by reducing anxiety, stress, and depression levels in the treatment group
Canine-assisted intervention reduces anxiety and stress in higher education students: a randomized controlled trial
The purpose of this study was to explore benefits of interacting with a canine on anxiety, stress, depression, and wellbeing in Higher Education (HE) students. Sixty participants took part in a randomized controlled trial. Assigned to either the canine-assisted intervention (CAI) or control group, the CAI group interacted with a canine whereas the control group watched an unrelated slideshow. Anxiety, depression, stress, and wellbeing measures were completed pre- and post-intervention and demonstrated there was a significant decrease in anxiety and stress in the CAI group. Due to group differences pre-intervention, findings for depression measures were uninterpretable and there was no significant effect found for general wellbeing. Overall, this study uses a CAI and control group and explores the use of a singular, brief CAI session in HE students demonstrating CAI to be an effective means of supporting mental health by decreasing levels of anxiety and stress in the treatment group
Are the Nuclei of Seyfert 2 Galaxies Viewed Face-On?
We show from modeling the Fe Kalpha line in the ASCA spectra of four X-ray
bright narrow emission line galaxies (Seyfert types 1.9 and 2) that two equally
viable physical models can describe the observed line profile. The first is
discussed by Turner et al. (1998) and consists of emission from a nearly
pole-on accretion disk. The second, which is statistically preferred, is a
superposition of emission from an accretion disk viewed at an intermediate
inclination of about 48 degrees and a distinct, unresolved feature that
presumably originates some distance from the galaxy nucleus. The intermediate
inclination is entirely consistent with unified schemes and our findings
challenge recent assertions that Seyfert 2 galaxies are preferentially viewed
with their inner regions face-on. We derive mean equivalent widths for the
narrow and disk lines of =60 eV and = 213 eV, respectively. The
X-ray data are well described by a geometry in which our view of the active
nucleus intersects and is blocked by the outer edges of the obscuring torus,
and therefore do not require severe misalignments between the accretion disk
and the torus.Comment: 19 pages, 3 postscript figures. Accepted for publication in ApJ
The Surveyor 3 and Surveyor 4 flight paths and their determination from tracking data
Surveyor 3 and 4 spacecraft flight path
Iron fluorescence from within the innermost stable orbit of black hole accretion disks
The fluorescent iron Ka line is a powerful observational probe of the inner
regions of black holes accretion disks. Previous studies have assumed that only
material outside the radius of marginal stability can contribute to the
observed line emission. Here, we show that fluorescence by material inside the
radius of marginal stability, which is in the process of spiralling towards the
event horizon, can have a observable influence on the iron line profile and
equivalent width. For concreteness, we consider the case of a geometrically
thin accretion disk, around a Schwarzschild black hole, in which fluorescence
is excited by an X-ray source placed at some height above the disk and on the
axis of the disk. Fully relativistic line profiles are presented for various
source heights and efficiencies. It is found that the extra line flux generally
emerges in the extreme red wing of the iron line, due to the large
gravitational redshift experienced by photons from the region within the radius
of marginal stability. We apply our models to the variable iron line seen in
the ASCA spectrum of the Seyfert nucleus MCG-6-30-15. It is found that the
change in the line profile, equivalent width, and continuum normalization, can
be well explained as being due to a change in the height of the source above
the disk. We discuss the implications of these results for distinguishing
rapidly-rotating black holes from slowly rotating holes using iron line
diagnostics.Comment: 20 pages, LaTeX. Accepted for publication in Astrophysical Journal.
Figures 3 to 7 replaced with corrected versions (previous figures affected by
calculational error). Some changes in the best fitting parameter
On the lack of X-ray iron line reverberation in MCG-6-30-15: Implications for the black hole mass and accretion disk structure
We use the method of Press, Rybicki & Hewitt (1992) to search for time lags
and time leads between different energy bands of the RXTE data for MCG-6-30-15.
We tailor our search in order to probe any reverberation signatures of the
fluorescent iron Kalpha line that is thought to arise from the inner regions of
the black hole accretion disk. In essence, an optimal reconstruction algorithm
is applied to the continuum band (2-4keV) light curve which smoothes out noise
and interpolates across the data gaps. The reconstructed continuum band light
curve can then be folded through trial transfer functions in an attempt to find
lags or leads between the continuum band and the iron line band (5-7keV). We
find reduced fractional variability in the line band. The spectral analysis of
Lee et al. (1999) reveals this to be due to a combination of an apparently
constant iron line flux (at least on timescales of few x 10^4s), and flux
correlated changes in the photon index. We also find no evidence for iron line
reverberation and exclude reverberation delays in the range 0.5-50ksec. This
extends the conclusions of Lee et al. and suggests that the iron line flux
remains constant on timescales as short as 0.5ksec. The large black hole mass
(>10^8Msun) naively suggested by the constancy of the iron line flux is
rejected on other grounds. We suggest that the black hole in MCG-6-30-15 has a
mass of M_BH~10^6-10^7Msun and that changes in the ionization state of the disk
may produce the puzzling spectral variability. Finally, it is found that the
8-15keV band lags the 2-4keV band by 50-100s. This result is used to place
constraints on the size and geometry of the Comptonizing medium responsible for
the hard X-ray power-law in this AGN.Comment: 11 pages, 13 postscript figures. Accepted for publication in Ap
The effect of disgust and fear modeling on childrenâs disgust and fear for animals
Disgust is a protective emotion associated with certain types of animal fears. Given that a primary function of disgust is to protect against harm, increasing childrenâs disgust-related beliefs for animals may affect how threatening they think animals are and their avoidance of them. One way that childrenâs disgust beliefs for animals might change is via vicarious learning: by observing others responding to the animal with disgust. In Experiment 1, children (ages 7â10 years) were presented with images of novel animals together with adult faces expressing disgust. Childrenâs fear beliefs and avoidance preferences increased for these disgust-paired animals compared with unpaired control animals. Experiment 2 used the same procedure and compared disgust vicarious learning with vicarious learning with fear faces. Childrenâs fear beliefs and avoidance preferences for animals again increased as a result of disgust vicarious learning, and animals seen with disgust or fear faces were also rated more disgusting than control animals. The relationship between increased fear beliefs and avoidance preferences for animals was mediated by disgust for the animals. The experiments demonstrate that children can learn to believe that animals are disgusting and threatening after observing an adult responding with disgust toward them. The findings also suggest a bidirectional relationship between fear and disgust with fear-related vicarious learning leading to increased disgust for animals and disgust-related vicarious learning leading to increased fear and avoidance
Suzaku observations of Markarian 335: evidence for a distributed reflector
We report on a 151 ks net exposure Suzaku observation of the Narrow Line
Seyfert 1 galaxy Mrk 335. The 0.5-40 keV spectrum contains a broad Fe line, a
strong soft excess below about 2 keV and a Compton hump around 20-30 keV. We
find that a model consisting of a power law and two reflectors provides the
best fit to the time-averaged spectrum. In this model, an ionized, heavily
blurred, inner reflector produces most of the soft excess, while an almost
neutral outer reflector (outside ~40 r_g) produces most of the Fe line
emission. The spectral variability of the observation is characterised by
spectral hardening at very low count rates. In terms of our power-law +
two-reflector model it seems like this hardening is mainly caused by pivoting
of the power law. The rms spectrum of the entire observation has the curved
shape commonly observed in AGN, although the shape is significantly flatter
when an interval which does not contain any deep dip in the lightcurve is
considered. We also examine a previous 133 ks XMM-Newton observation of Mrk
335. We find that the XMM-Newton spectrum can be fitted with a similar
two-reflector model as the Suzaku data and we confirm that the rms spectrum of
the observation is flat. The flat rms spectra, as well as the high-energy data
from the Suzaku PIN detector, disfavour an absorption origin for the soft
excess in Mrk 335.Comment: 13 pages, 13 figures. Accepted for publication in MNRA
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