8,208 research outputs found
Noticing for Equity to Sustain Multilingual Literacies
This department explores how teachers can sustain students’ multilingual literacies and reimagine literacy learning across multiple contexts in conversation with researchers, practitioners, and communities
Nova Sagittarii 1998 (V4633 Sgr) - a permanent superhump system or an asynchronous polar?
We report the results of observations of V4633 Sgr (Nova Sagittarii 1998)
during 1998-2000. Two photometric periodicities were present in the light curve
during the three years of observations: a stable one at P=3.014 h, which is
probably the orbital period of the underlying binary system, and a second one
of lower coherence, approximately 2.5 per cent longer than the former. The
latter periodicity may be a permanent superhump, or alternatively, the spin
period of the white dwarf in a nearly synchronous magnetic system. A third
period, at P=5.06 d, corresponding to the beat between the two periods was
probably present in 1999. Our results suggest that a process of mass transfer
took place in the binary system since no later than two and a half months after
the nova eruption. We derive an interstellar reddening of E(B-V)~0.21 from our
spectroscopic measurements and published photometric data, and estimate a
distance of d~9 kpc to this nova.Comment: 13 pages, latex, 7 figures, accepted for publication in MNRA
Diverter AI based decision aid, phases 1 and 2
It was determined that a system to incorporate artificial intelligence (AI) into airborne flight management computers is feasible. The AI functions that would be most useful to the pilot are to perform situational assessment, evaluate outside influences on the contemplated rerouting, perform flight planning/replanning, and perform maneuver planning. A study of the software architecture and software tools capable of demonstrating Diverter was also made. A skeletal planner known as the Knowledge Acquisition Development Tool (KADET), which is a combination script-based and rule-based system, was used to implement the system. A prototype system was developed which demonstrates advanced in-flight planning/replanning capabilities
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Using a runway paradigm to assess the relative strength of rats' motivations for enrichment objects
Laboratory animals should be provided with enrichment objects in their cages; however, it is first necessary to
test whether the proposed enrichment objects provide benefits that increase the animals’ welfare. The two main
paradigms currently used to assess proposed enrichment objects are the choice test, which is limited to determining
relative frequency of choice, and consumer demand studies, which can indicate the strength of a preference but are complex to design. Here, we propose a third methodology: a runway paradigm, which can be used to assess the strength of an animal’s motivation for enrichment objects, is simpler to use than consumer demand studies, and is faster to complete than typical choice tests. Time spent with objects in a standard choice test was used to rank several enrichment objects in order to compare with the ranking found in our runway paradigm. The rats ran significantly more times, ran faster, and interacted longer with objects with which they had previously spent the most time. It was concluded that this simple methodology is suitable for measuring rats’ motivation to reach enrichment objects. This can be used to assess the preference for different types of enrichment objects or to measure reward system processes
Twisted accretion curtains in the intermediate polar FO Aquarii
We report on a ~37-ks XMM-Newton observation of the intermediate polar FO
Aquarii, presenting X-ray and UV data from the EPIC and OM cameras. We find
that the system has changed from its previously reported state of disc-overflow
accretion to one of purely disc-fed accretion. We detect the previously
reported `notch' feature in the X-ray spin pulse, and explain it as a partial
occultation of the upper accretion pole. Maximum flux of the quasi-sinusoidal
UV pulse coincides with the notch, in keeping with this idea. However, an
absorption dip owing to the outer accretion curtains occurs 0.27 later than the
expected phase, which implies that the accretion curtains are twisted, trailing
the magnetic poles. This result is the opposite of that reported in PQ Gem,
where accreting field lines were found to lead the pole. We discuss how such
twists relate to the accretion torques and thus the observed period changes of
the white dwarfs, but find no simple connection.Comment: 7 pages, 5 figures. Accepted by MNRA
Syndecan-3 is selectively pro-inflammatory in the joint and contributes to antigen-induced arthritis in mice
INTRODUCTION: Syndecans are heparan sulphate proteoglycans expressed by endothelial cells. Syndecan-3 is expressed by synovial endothelial cells of rheumatoid arthritis (RA) patients where it binds chemokines, suggesting a role in leukocyte trafficking. The objective of the current study was to examine the function of syndecan-3 in joint inflammation by genetic deletion in mice and compare with other tissues. METHODS: Chemokine C-X-C ligand 1 (CXCL1) was injected in the joints of syndecan-3-/-and wild-type mice and antigen-induced arthritis performed. For comparison chemokine was administered in the skin and cremaster muscle. Intravital microscopy was performed in the cremaster muscle. RESULTS: Administration of CXCL1 in knee joints of syndecan-3-/-mice resulted in reduced neutrophil accumulation compared to wild type. This was associated with diminished presence of CXCL1 at the luminal surface of synovial endothelial cells where this chemokine clustered and bound to heparan sulphate. Furthermore, in the arthritis model syndecan-3 deletion led to reduced joint swelling, leukocyte accumulation, cartilage degradation and overall disease severity. Conversely, CXCL1 administration in the skin of syndecan-3 null mice provoked increased neutrophil recruitment and was associated with elevated luminal expression of E-selectin by dermal endothelial cells. Similarly in the cremaster, intravital microscopy showed increased numbers of leukocytes adhering and rolling in venules in syndecan-3-/-mice in response to CXCL1 or tumour necrosis factor alpha. CONCLUSIONS: This study shows a novel role for syndecan-3 in inflammation. In the joint it is selectively pro-inflammatory, functioning in endothelial chemokine presentation and leukocyte recruitment and cartilage damage in an RA model. Conversely, in skin and cremaster it is anti-inflammatory
An Irradiation Effect in Nova DN Gem 1912 and the Significance of the Period Gap for Classical Novae
Continuous CCD photometry of the classical nova DN Gem during 52 nights in
the years 1992-98 reveals a modulation with a period 0.127844 d. The
semi-amplitude is about 0.03 mag. The stability of the variation suggests that
it is the orbital period of the binary system. This interpretation makes DN Gem
the fourth nova inside the cataclysmic variable (CV) period gap, as defined by
Diaz and Bruch (1997), and it bolsters the idea that there is no period gap for
classical novae. However, the number of known nova periods is still too small
to establish this idea statistically. We eliminate several possible mechanisms
for the variation, and propose that the modulation is driven by an irradiation
effect. We find that model light curves of an irradiated secondary star, fit
the data well. The inclination angle of the system is restricted by this model
to 10 deg < i < 65 deg. We also refine a previous estimate of the distance to
the binary system, and find d=1.6+/-0.6 kpc.Comment: 7 pages, Latex file, 2 .ps files and 3 .eps files. accepted for
publication in MNRAS. also available at:
ftp://ftp.astro.keele.ac.uk/pub/preprints/preprints.htm
XSS J00564+4548 and IGR J00234+6141 -- new cataclysmic variables from RXTE and INTEGRAL all sky surveys
We present the results of optical identification of two X-ray sources from
RXTE and INTEGRAL all sky surveys: XSS J00564+4548 and IGR J00234+6141. Using
the optical data from Russian-Turkish 1.5-m Telescope (RTT150) and SWIFT X-ray
observations, we show that these sources most probably are intermediate polars,
i.e. binary systems with accreting white dwarfs with not very strong magnetic
field (<~10 MG). Periodical oscillations of optical emission with periods 480 s
and 570 s were found. We argue that these periods most probably correspond to
the rotating periods of the white dwarfs in these systems. Further optical
observations scheduled at RTT150 will allow to study the parameters of these
systems in more detail.Comment: 5 pages, 8 figures, accepted for publication in Astronomy Letter
Integrating Biological and Social Processes in Relation to Early-Onset Persistent Aggression in Boys and Girls
This study examined the relationship between biological and social risk factors and aggressive behavior patterns in an Australian high-risk sample of 370 adolescents. Perinatal, temperamental, familial, sociodemographic, and behavioral data were collected during interviews completed during pregnancy, immediately postpartum, and when the children were 6 months old and 5, 14, and 15 years old. Youths were given tests of verbal and neuropsychological functioning at the age 5 and age 15 follow-ups. Youths were divided into early-onset persistent aggression, adolescent-onset aggression, and nonaggressive behavior groups. Results revealed that the interaction of biological and social risk factors was significantly related to early-onset persistent aggression. Gender and developmental phase of measurement moderated the relationship between biosocial risks and the outcomes of early-onset persistent aggression and adolescent-onset aggression
Evidence for ablated flows in the shell of nova DQ Her
High-resolution longslit Halpha spectra of the shell of the old nova DQ Her
have been obtained with the William Herschel Telescope using the ISIS
spectrograph. An equatorial expansion velocity of 370+/-14 km/s is derived from
the spectra which, in conjunction with a narrowband Halpha image of the
remnant, allows a distance estimate of 525+/-28 pc. An equatorial ring which
exhibits enhanced [NII] emission has also been detected and the inclination
angle of the shell is found to be 86.8+/-0.2 degrees with respect to the line
of sight. The spectra also reveal tails extending from the clumps in the shell,
which have a radial velocity increasing along their length. This suggests the
presence of a stellar wind, collimated in the polar direction, which ablates
fragments of material from the clumps and accelerates them into its stream up
to a terminal velocity of order 800-900 km/s.Comment: 7 pages, 6 figure
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