2,546 research outputs found
Net gen or not gen? Student and Staff Evaluations of the use of Podcasts/Audio Files and an Electronic Voting System (EVS) in a Blended Learning Module.
At the authors’ institution, blended learning is defined as “educational provision where high quality e-learning opportunities and excellent campus-based learning are combined or blended in coherent, reflective and innovative ways so that learning is enhanced and choice is increased. Students are at the centre of this vision”.
This paper outlines work undertaken to investigate the impact of integrating podcasts/audio file downloads and use of an electronic voting system (EVS) to transform module delivery from a traditional mode to a blended delivery. The purpose being to introduce a measure of flexibility in how, when and where students study; to increase interactivity and engagement in classroom sessions, and to enhance students' learning.
The student cohort is diverse in respect of age – the majority or students are direct entry students of the so-called net generation, whilst a significant number of students (35%) are mature students. Would age be an influencing factor on the students’ preference for the learning methods employed, or their willingness or ability to engage with the technologies?
An interim student evaluation was undertaken at the midpoint of the taught module, to provide formative, illustrative data to the module leader and teaching team about student opinion of the teaching methods and learning technologies. Given the option of returning to the traditional delivery method, 77.5% of students either “agreed” or “strongly agreed” that the module should continue to run in its blended format.
The final evaluation discovered no discernable differences in the behaviour of the direct entry students compared to the mature students. Both groups accessed the podcasts easily, generally at home, and spent longer than if blended learning technologies had not been used. It was discovered that 16% of the mature and 24% of the direct entry students would have preferred lectures to podcasts, although the students were positive about the flexibility offered. Both groups of students were virtually unanimous on the benefits of the EVS to support learning. The teaching team concluded that the blended learning technologies increased the students’ engagement with their learning
Incorporating learning technologies into undergraduate radiography education
Original article can be found at: http://www.sciencedirect.com/science/journal/10788174 Copyright The College of RadiographersThis study investigated the impact of integrating podcasts/audio file downloads and use of an electronic voting system (EVS) on a previously traditionally taught module. Both student (direct entry and mature) and staff satisfaction with the modified structure were evaluated.Peer reviewe
An empirical Bayesian analysis applied to the globular cluster pulsar population
We describe an empirical Bayesian approach to determine the most likely size
of an astronomical population of sources of which only a small subset are
observed above some limiting flux density threshold. The method is most
naturally applied to astronomical source populations at a common distance
(e.g.,stellar populations in globular clusters), and can be applied even to
populations where a survey detects no objects. The model allows for the
inclusion of physical parameters of the stellar population and the detection
process. As an example, we apply this method to the current sample of radio
pulsars in Galactic globular clusters. Using the sample of flux density limits
on pulsar surveys in 94 globular clusters published by Boyles et al., we
examine a large number of population models with different dependencies. We
find that models which include the globular cluster two-body encounter rate,
, are strongly favoured over models in which this is not a factor. The
optimal model is one in which the mean number of pulsars is proportional to
. This model agrees well with earlier work by Hui et al.
and provides strong support to the idea that the two-body encounter rate
directly impacts the number of neutron stars in a cluster. Our model predicts
that the total number of potentially observable globular cluster pulsars in the
Boyles et al. sample is 1070, where the uncertainties signify
the 95% confidence interval. Scaling this result to all Galactic globular
clusters, and to account for radio pulsar beaming, we estimate the total
population to be 2280.Comment: 8 pages, 6 figures, 3 tables, corrected a few minor formatting errors
which have also been submitted as an erratum to MNRA
Isolated pulsar spin evolution on the P-Pdot Diagram
We look at two contrasting spin-down models for isolated radio pulsars and,
accounting for selection effects, synthesize observable populations. While our
goal is to reproduce all of the observable characteristics, in this paper we
pay particular attention to the form of the spin period vs. period derivative
(P-Pdot) diagram and its dependence on various pulsar properties. We analyse
the initial spin period, the braking index, the magnetic field, various beaming
models, as well as the pulsar's luminosity. In addition to considering the
standard magnetic dipole model for pulsar spin-down, we also consider the
recent hybrid model proposed by Contopoulos & Spitkovsky. The magnetic dipole
model, however, does a better job of reproducing the observed pulsar
population. We conclude that random alignment angles and period dependent
luminosity distributions are essential to reproduce the observed P-Pdot
diagram. We also consider the time decay of alignment angles, and attempt to
reconcile various models currently being studied. We conclude that, in order to
account for recent evidence for the alignment found by Weltevrede & Johnston,
the braking torque on a neutron star should not depend strongly on the
inclination. Our simulation code is publically available and includes a
web-based interface to examine the results and make predictions for yields of
current and future surveys.Comment: 9 pages, 4 figure
Why the distance of PSR J0218+4232 does not challenge pulsar emission theories
Recent VLBI measurements of the astrometric parameters of the millisecond
pulsar J0218+4232 by Du et al. have suggested this pulsar is as distant as 6.3
kpc. At such a large distance, the large {\gamma}-ray flux observed from this
pulsar would make it the most luminous {\gamma}-ray pulsar known. This
luminosity would exceed what can be explained by the outer gap and slot-gap
pulsar emission models, potentially placing important and otherwise elusive
constraints on the pulsar emission mechanism. We show that the VLBI parallax
measurement is dominated by the Lutz-Kelker bias. When this bias is corrected
for, the most likely distance for this pulsar is 3.15(+0.85/-0.60) kpc. This
revised distance places the luminosity of PSR J0218+4232 into a range where it
does not challenge any of the standard theories of the pulsar emission
mechanism.Comment: 3 pages, 2 figures, 1 table. Accepted for publication in MNRA
Discovery of Five New Pulsars in Archival Data
Reprocessing of the Parkes Multibeam Pulsar Survey has resulted in the
discovery of five previously unknown pulsars and several as-yet-unconfirmed
candidates. PSR J0922-52 has a period of 9.68 ms and a DM of 122.4 pc cm^-3.
PSR J1147-66 has a period of 3.72 ms and a DM of 133.8 pc cm^-3. PSR J1227-6208
has a period of 34.53 ms, a DM of 362.6 pc cm^-3, is in a 6.7 day binary orbit,
and was independently detected in an ongoing high-resolution Parkes survey by
Thornton et al. and also in independent processing by Einstein@Home volunteers.
PSR J1546-59 has a period of 7.80 ms and a DM of 168.3 pc cm^-3. PSR J1725-3853
is an isolated 4.79-ms pulsar with a DM of 158.2 pc cm^-3. These pulsars were
likely missed in earlier processing efforts due to their high DMs and short
periods and the large number of candidates that needed to be looked through.
These discoveries suggest that further pulsars are awaiting discovery in the
multibeam survey data.Comment: 12 pages, 2 figures, 2 tables, accepted to Ap
Nano-Hertz Gravitational Waves Searches with Interferometric Pulsar Timing Experiments
We estimate the sensitivity to nano-Hertz gravitational waves of pulsar
timing experiments in which two highly-stable millisecond pulsars are tracked
simultaneously with two neighboring radio telescopes that are referenced to the
same time-keeping subsystem (i.e. "the clock"). By taking the difference of the
two time-of-arrival residual data streams we can exactly cancel the clock noise
in the combined data set, thereby enhancing the sensitivity to gravitational
waves. We estimate that, in the band () Hz, this
"interferometric" pulsar timing technique can potentially improve the
sensitivity to gravitational radiation by almost two orders of magnitude over
that of single-telescopes. Interferometric pulsar timing experiments could be
performed with neighboring pairs of antennas of the forthcoming large arraying
projects.Comment: Paper submitted to Phys. Rev. Letters. It is 9 pages long, and
includes 2 figure
Gravitational wave background from rotating neutron stars
The background of gravitational waves produced by the ensemble of rotating
neutron stars (which includes pulsars, magnetars and gravitars) is
investigated. A formula for \Omega(f) (commonly used to quantify the
background) is derived, properly taking into account the time evolution of the
systems since their formation until the present day. Moreover, the formula
allows one to distinguish the different parts of the background: the
unresolvable (which forms a stochastic background) and the resolvable. Several
estimations of the background are obtained, for different assumptions on the
parameters that characterize neutron stars and their population. In particular,
different initial spin period distributions lead to very different results. For
one of the models, with slow initial spins, the detection of the background can
be rejected. However, other models do predict the detection of the background
by the future ground-based gravitational wave detector ET. A robust upper limit
for the background of rotating neutron stars is obtained; it does not exceed
the detection threshold of two cross-correlated Advanced LIGO interferometers.
If gravitars exist and constitute more than a few percent of the neutron star
population, then they produce an unresolvable background that could be detected
by ET. Under the most reasonable assumptions on the parameters characterizing a
neutron star, the background is too faint. Previous papers have suggested
neutron star models in which large magnetic fields (like the ones that
characterize magnetars) induce big deformations in the star, which produce a
stronger emission of gravitational radiation. Considering the most optimistic
(in terms of the detection of gravitational waves) of these models, an upper
limit for the background produced by magnetars is obtained; it could be
detected by ET, but not by BBO or DECIGO.Comment: 25 pages, 15 figure
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