8,208 research outputs found

    Noticing for Equity to Sustain Multilingual Literacies

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    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?

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    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

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    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

    Twisted accretion curtains in the intermediate polar FO Aquarii

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    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

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    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

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    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

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    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

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    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

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    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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