1,050 research outputs found
We Thought We Knew the Landscape of Literacy Teacher Education: Ten Surprises From Our Research
Vol. 6. No. 2 Nov 2016
In this month's edition of RiTE we are fortunate to have not one but three! Clare Kosnik is Director of the Dr. Eric Jackman Institute of Child Study at the Ontario Institute for Studies in Education, University of Toronto (OISE/UT). Her area of research is teacher education which she has systematically studied. She is now conducting a large-scale study of 28 literacy/English teacher educators in four countries.
Lydia Menna is an Assistant Professor of Language and Literacy in the Department of Elementary Education at the University of Alberta. Her research interests are in the areas of teacher education, multiliteracies, critical literacy, and teacher identity construction. She completed her doctorate in the Department of Curriculum, Teaching, and Learning at the Ontario Institute for Studies in Education, University of Toronto.
Pooja Dharamshi is an Assistant Professor of Teacher Education in the Faculty of Education at Simon Fraser University. Her research interests are in the areas of critical literacy and teacher education. She recently completed her doctoral studies at the Ontario Institute for Studies in Education/ University of Toronto in the department of Curriculum, Teaching, and Learning. Her study explored the practices and pedagogies of literacy teacher educators with a critical stance
Measuring the spin up of the Accreting Millisecond Pulsar XTE J1751-305
We perform a timing analysis on RXTE data of the accreting millisecond pulsar
XTE J1751-305 observed during the April 2002 outburst. After having corrected
for Doppler effects on the pulse phases due to the orbital motion of the
source, we performed a timing analysis on the phase delays, which gives, for
the first time for this source, an estimate of the average spin frequency
derivative = (3.7 +/- 1.0)E-13 Hz/s. We discuss the torque resulting
from the spin-up of the neutron star deriving a dynamical estimate of the mass
accretion rate and comparing it with the one obtained from X-ray flux.
Constraints on the distance to the source are discussed, leading to a lower
limit of \sim 6.7 kpc.Comment: 7 pages, 3 figures, Accepted for publication by MNRA
Timing of the Accreting Millisecond Pulsar XTE J1814-338
We present a precise timing analysis of the accreting millisecond pulsar XTE
J1814-338 during its 2003 outburst, observed by RXTE. A full orbital solution
is given for the first time; Doppler effects induced by the motion of the
source in the binary system were corrected, leading to a refined estimate of
the orbital period, P_orb=15388.7229(2)s, and of the projected semimajor axis,
a sini/c= 390.633(9) lt-ms. We could then investigate the spin behaviour of the
accreting compact object during the outburst. We report here a refined value of
the spin frequency (nu=314.35610879(1) Hz) and the first estimate of the spin
frequency derivative of this source while accreting (nu^dot=(-6.7 +/- 0.7)
10^(-14) Hz/s). This spin down behaviour arises when both the fundamental
frequency and the second harmonic are taken into consideration. We discuss this
in the context of the interaction between the disc and the quickly rotating
magnetosphere, at accretion rates sufficiently low to allow a threading of the
accretion disc in regions where the Keplerian velocity is slower than the
magnetosphere velocity. We also present indications of a jitter of the pulse
phases around the mean trend, which we argue results from movements of the
accreting hotspots in response to variations of the accretion rate.Comment: 7 pages, 4 figures, Accepted for publication by MNRA
Methodological and terminological issues in animal-assisted interventions: An umbrella review of systematic reviews
Recently, animal-assisted interventions (AAIs), which are defined as psychological, educational, and rehabilitation support activities, have become widespread in different contexts. For many years, they have been a subject of interest in the international scientific community and are at the center of an important discussion regarding their effectiveness and the most appropriate practices for their realization. We carried out an umbrella review (UR) of systematic reviews (SRs), created for the purpose of exploring the literature and aimed at deepening the terminological and methodological aspects of AAIs. It is created by exploring the online databases PubMed, Google Scholar, and Cochrane Library. The SRs present in the high-impact indexed search engines Web of Sciences and Scopus are selected. After screening, we selected 15 SRs that met the inclusion criteria. All papers complained of the poor quality of AAIs; some considered articles containing interventions that did not always correspond to the terminology they have explored and whose operating practices were not always comparable. This stresses the need for the development and consequent diffusion of not only operational protocols, but also research protocols which provide for the homogeneous use of universally recognized terminologies, thus facilitating the study, deepening, and comparison between the numerous experiences described
Diagnosis of centrocestus formosanus infection in zebrafish (Danio rerio) in Italy: A window to a new globalization-derived invasive microorganism
Centrocestus formosanus is a digenetic trematode with a complex life cycle, involving invertebrate and vertebrate hosts, humans included. In particular, it causes gill lesions and mortality in freshwater fish species, and gastrointestinal symptoms in infected humans. Here, we describe the occurrence of C. formosanus infection in zebrafish imported in Italy and propose a newly designed species-specific primer pair to ameliorate the diagnostic investigations for C. formosanus. Gill arches of 30 zebrafish were examined for the presence of encysted metacercariae under a stereomicroscope and processed through molecular analyses targeting the ribosomal internal transcribed sequence 2 (ITS2). Although C. formosanus distribution was originally restricted to Asia, it has been subsequently reported in new countries, revealing itself as an invasive species and raising important concerns for biodiversity, economy, scientific research, as well as animal and public health. Given the crucial role played by the ornamental fish industry in spreading this parasite, there is an urgent need for control measures to prevent the introduction and establishment of C. formosanus in non-endemic areas, including Europe. We also suggest developing new strategies in microbiology and epidemiology to better explore this new globalization-derived invasive species
Timing of the accreting millisecond pulsar IGR~J17511--3057
{Timing analysis of Accretion-powered Millisecond Pulsars (AMPs) is a
powerful tool to probe the physics of compact objects. The recently discovered
\newigrj is the 12 discovered out of the 13 AMPs known. The Rossi XTE satellite
provided an extensive coverage of the 25 days-long observation of the source
outburst.} {Our goal is to investigate the complex interaction between the
neutron star magnetic field and the accretion disk, determining the angular
momentum exchange between them. The presence of a millisecond coherent flux
modulation allows us to investigate such interaction from the study of pulse
arrival times. In order to separate the neutron star proper spin frequency
variations from other effects, a precise set of orbital ephemeris is
mandatory.} {Using timing techniques, we analysed the pulse phase delays
fitting differential corrections to the orbital parameters. To remove the
effects of pulse phase fluctuations we applied the timing technique already
successfully applied to the case of an another AMP, XTE J1807-294.} {We report
a precise set of orbital ephemeris. We demonstrate that the companion star is a
main sequence star. We find pulse phase delays fluctuations on the first
harmonic with a characteristic amplitude of about 0.05, similar to what also
observed in the case of the AMP XTE J1814-338. For the second time an AMP shows
a third harmonic detected during the entire outburst. The first harmonic phase
delays show a puzzling behaviour, while the second harmonic phase delays show a
clear spin-up. Also the third harmonic shows a spin-up, although not highly
significant (3 c.l.). The presence of a fourth harmonic is also
reported. In the hypothesis that the second harmonic is a good tracer of the
spin frequency of the neutron star, we find a mean spin frequency derivative
for this source of \np{1.65(18)}{-13} Hz s.} (continue ...)Comment: 9 pages, 12 figures, A&A accepted on 23/10/201
Spin up and phase fluctuations in the timing of the accreting millisecond pulsar XTE J1807-294
We performed a timing analysis of the 2003 outburst of the accreting X-ray
millisecond pulsar XTE J1807-294 observed by RXTE. Using recently refined
orbital parameters we report for the first time a precise estimate of the spin
frequency and of the spin frequency derivative. The phase delays of the pulse
profile show a strong erratic behavior superposed to what appears as a global
spin-up trend. The erratic behavior of the pulse phases is strongly related to
rapid variations of the light curve, making it very difficult to fit these
phase delays with a simple law. As in previous cases, we have therefore
analyzed separately the phase delays of the first harmonic and of the second
harmonic of the spin frequency, finding that the phases of the second harmonic
are far less affected by the erratic behavior. In the hypothesis that the
second harmonic pulse phase delays are a good tracer of the spin frequency
evolution we give for the first time a estimation of the spin frequency
derivative in this source. The source shows a clear spin-up of Hz sec (1 confidence level). The
largest source of uncertainty in the value of the spin-up rate is given by the
uncertainties on the source position in the sky. We discuss this systematics on
the spin frequency and its derivative.Comment: 17 pages, 4 figures, Accepted by Ap
IMAGE ORIENTATION WITH A HYBRID PIPELINE ROBUST TO ROTATIONS AND WIDE-BASELINES
The extraction of reliable and repeatable interest points among images is a fundamental step for automatic image orientation (Structure-From-Motion). Despite recent progresses, open issues in challenging conditions - such as wide baselines and strong light variations - are still present. Over the years, traditional hand-crafted methods have been paired by learning-based approaches, progressively updating the state-of-the-art according to recent benchmarks. Notwithstanding these advancements, learning-based methods are often not suitable for real photogrammetric surveys due to their lack of rotation invariance, a fundamental requirement for these specific applications. This paper proposes a novel hybrid image matching pipeline which employs both hand-crafted and deep-based components, to extract reliable rotational invariant keypoints optimized for wide-baseline scenarios. The proposed hybrid pipeline was compared with other hand-crafted and learning-based state-of-the-art approaches on some photogrammetric datasets using metric ground-truth data. Results show that the proposed hybrid matching pipeline has high accuracy and appeared to be the only method among the evaluated ones able to register images in the most challenging wide-baseline scenarios
Coupling Between Periodic and Aperiodic Variability in SAX J1808.4-3658
We detect a significant broadening in the wings of the 401 Hz peak in the
power spectrum of the accreting millisecond binary pulsar SAX J1808.4-3658.
This feature is consistent with the convolution of the red noise present in the
power spectrum with the harmonic line. We conclude that the flux modulated by
the spin period shows aperiodic variability similar to the red noise in the
overall flux, suggesting such variability also originates at the magnetic caps
close to the neutron star surface. This is analogous to the results found in
some longer period, higher magnetic field pulsators in high mass X-ray
binaries.Comment: 16 pages, 3 figures, to be published in The Astrophysical Journa
Temporal Analysis of the Millisecond X-ray Pulsar SAX J1808.4-3658 During the 2000 Outburst
We report a temporal analysis of the millisecond X-ray Pulsar SAX J1808.4-3658 during the 2000 outburst, observed with RXTE. The observed maximum luminosity was approximately a factor of ten lower than in the other outbursts exhibited by the source, and this low flux level forced us to use a technique based on the χ2 obtained with an epoch folding search to discriminate between different possible orbital solutions, in order to correct the data for the orbital motion. In the subsequent searches for periodicities we clearly detected the 401Hz pulsation in at least two observations, but in the faintest the pulsed fraction varied from 20 % ca. to the absence of signs of coherent pulsation at all, while the measured flux remained at an almost constat level. This erratic behaviour is discussed in the context of the centrifugal inhibition of accretion
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