5,557 research outputs found
Teaching and critically reflective practice in Freire
Few of the many books written by Freire drew particular, and extended, attention to the teacher in the way Pedagogy of Freedom (1998) was able to do. While this entry draws on many other important works by Freire, it specifically probes elements of this book to place before readers some of the salient qualities and attributes Freire believed teachers, educators and thinkers of education ought to aspire to
Chandra studies of the globular cluster 47 Tucanae: A deeper X-ray source catalogue, five new X-ray counterparts to millisecond radio pulsars, and new constraints to r-mode instability window
We combined Chandra ACIS observations of the globular cluster 47 Tucanae
(hereafter, 47 Tuc) from 2000, 2002, and 2014-15 to create a deeper X-ray
source list, and study some of the faint radio millisecond pulsars (MSPs)
present in this cluster. We have detected 370 X-ray sources within the
half-mass radius (2.79) of the cluster, 81 of which are newly identified, by
including new data and using improved source detection techniques. The majority
of the newly identified sources are in the crowded core region, indicating
cluster membership. We associate five of the new X-ray sources with
chromospherically active BY Dra or W UMa variables identified by Albrow et al.
(2001). We present alternative positions derived from two methods, centroiding
and image reconstruction, for faint, crowded sources. We are able to extract
X-ray spectra of the recently discovered MSPs 47 Tuc aa, 47 Tuc ab, the newly
timed MSP 47 Tuc Z, and the newly resolved MSPs 47 Tuc S and 47 Tuc F.
Generally, they are well fit by black body or neutron star atmosphere models,
with temperatures, luminosities and emitting radii similar to those of other
known MSPs in 47 Tuc, though 47 Tuc aa and 47 Tuc ab reach lower X-ray
luminosities. We limit X-ray emission from the full surface of the rapidly
spinning (542 Hz) MSP 47 Tuc aa, and use this limit to put an upper bound for
amplitude of r-mode oscillations in this pulsar as
and constrain the shape of the r-mode instability window.Comment: 17 pages, 11 figures, 6 tables, Accepted for publication in MNRA
Radio Timing and Optical Photometry of the Black Widow System PSR J1953+1846A in the Globular Cluster M71
We report on the determination of the astrometric, spin and orbital
parameters for PSR J1953+1846A, a "black widow" binary millisecond pulsar in
the globular cluster M71. By using the accurate position and orbital parameters
obtained from radio timing, we identified the optical companion in ACS/Hubble
Space Telescope images. It turns out to be a faint (m_F606W>=24, m_F814W>=23)
and variable star located at only ~0.06" from the pulsar timing position. The
light curve shows a maximum at the pulsar inferior conjunction and a minimum at
the pulsar superior conjunction, thus confirming the association with the
system. The shape of the optical modulation suggests that the companion star is
heated, likely by the pulsar wind. The comparison with the X-ray light curve
possibly suggests the presence of an intra-binary shock due to the interaction
between the pulsar wind and the material released by the companion. This is the
second identification (after COM-M5C) of an optical companion to a black widow
pulsar in a globular cluster. Interestingly, the two companions show a similar
light curve and share the same position in the color magnitude diagram.Comment: Accepted for publication by ApJ; 33 Pages, 10 Figures, 3 Table
Radio timing and optical photometry of the black widow system PSR J1518+0204C in the globular cluster M5
We report on the determination of astrometric, spin and orbital parameters
for PSR J1518+0204C, a "black widow" binary millisecond pulsar in the globular
cluster M5. The accurate position and orbital parameters obtained from radio
timing allowed us to search for the optical companion. By using WFC3/HST images
we identified a very faint variable star (m_F390W > 24.8, m_F606W > 24.3,
m_F814W > 23.1) located at only 0.25" from the pulsar's timing position. Due to
its strong variability, this star is visible only in a sub-sample of images.
However, the light curve obtained folding the available data with the orbital
parameters of the pulsar shows a maximum at the pulsar inferior conjunction and
a possible minimum at the pulsar superior conjunction. Furthermore, the shape
of the optical modulation indicates a heating process possibly due to the
pulsar wind. This is the first identification of an optical companion to a
black widow pulsar in the dense stellar environment of a globular cluster.Comment: Accepted for publication by ApJ; 24 Pages, 5 Figures, 1 Tabl
Pertinência da criação de um modelo geral de aceitação de tecnologia aplicado a terapias
Introdução: Conhecer os principais fatores que afetam a aceitação e utilização da tecnologia nos diferentes utilizadores e em diferentes contextos de saúde pode contribuir para o sucesso na implementação de novas ferramentas tecnológicas que permitam ajudar ao desempenho das diferentes tarefas. Objetivo: O presente estudo tem como objetivo obter a opinião de peritos na área de aceitação da tecnologia em contextos de saúde, relativa à pertinência de criação de um modelo geral de eTerapia que possa ser aplicado a diferentes utilizadores e com diferentes tarefas. Método: Inquérito por questionário a autores de literatura científica na área de aceitação da tecnologia em contextos de saúde. Resultados: Os resultados permitem verificar que seria importante a criação de um modelo de aceitação de tecnologia aplicado a terapias, que pudesse ser aplicado a diferentes tipos de utilizadores e que considerasse a diversidade de tarefas
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