8,859 research outputs found
Exploring the notion of quality in quality higher education assessment in a collaborative future
The purpose of this paper is to contribute to the debate on the notion of quality in higher education with particular focus on âobjectifying through articulationâ the assessment of quality by professional experts. The paper gives an overview of the differentiations of quality as used in higher education. It explores a substantial piece of evaluation research which was carried out between 2009 and 2011 by the authors at the Institute for Work Based Learning at Middlesex University
The volumetric rate of calcium-rich transients in the local universe
We present a measurement of the volumetric rate of `calcium-rich' optical
transients in the local universe, using a sample of three events from the
Palomar Transient Factory (PTF). This measurement builds on a detailed study of
the PTF transient detection efficiencies, and uses a Monte Carlo simulation of
the PTF survey. We measure the volumetric rate of calcium-rich transients to be
higher than previous estimates: events
yr Mpc. This is equivalent to 33-94% of the local volumetric type
Ia supernova rate. This calcium-rich transient rate is sufficient to reproduce
the observed calcium abundances in galaxy clusters, assuming an asymptotic
calcium yield per calcium-rich event of ~0.05. We also
study the PTF detection efficiency of these transients as a function of
position within their candidate host galaxies. We confirm as a real physical
effect previous results that suggest calcium-rich transients prefer large
physical offsets from their host galaxies.Comment: Accepted for publication in ApJ. 9 pages, 5 figure
The crustal structure of the east Africa through earthquake seismology
First arrivals of local and regional earthquakes, recorded at the Kaptagat array station on the western flank of the Gregory Rift Valley in Kenya, have been analysed to determine the crustal structure westward from the Rift axis. Apparent velocities have been interpreted in terms of crustal velocities. Azimuth and epicentral distance of event has provided lateral and vertical control on crustal boundaries. Normal shield crust, underlain by normal Moho is concluded to exist on the western flank of the Rift Valley. From the satisfactory propagation of S(_n) from events originating around the western Rift, normal Moho is considered to exist across the East African Plateau. A massive mantle derived intrusion is concluded to have penetrated the crust to within approximately 8 km of the Rift floor. This intrusion reaches to within about 7 km of the Elgeyo escarpment, the major Rift Valley boundary fault immediately to the east of Kaptagat. In order to aid second arrival analysis, a synthetic seismogram programme based on short wavelength asymptotic theory for reflected and refracted waves has been written. A qualitative analysis of real and synthetic seismograms of events originating to the west of Kaptagat, suggests that the crustal structure is more complex than the simple two- layered model initially produced. It is considered that the structure beneath the Gregory Rift is more equivalent to that beneath ocean Rift Systems than that beneath continental Rifts. However, rather than being a direct extension of the "World Rift System, the Eastern Rift and associated Kenya dome should be considered as a single physical unft
The professional and personal values and their revelation through professional doctorates
This paper discusses the relationship between individual practitionersâ personal values and their developing professional agentic values. It considers how the former might be in tension with the prescribed forms of practice held to be âprofessionalâ by professional bodies, warranting membership and, indeed, any licence to practice. These practices and their underpinning values have a functionality that may be at odds with the personal values of new professionals as their careers develop and they learn more, both propositionally and tacitly, within the profession. Becoming a professional within the cocoon of the profession is a career-long engagement and commitment. The cocoon and its values may be challenged by practice at the periphery of the professional domainâfor instance multi-disciplinary lawyersâ and accountantsâ practiceâor by critical reflection on individualsâ own practice and the hidden values that sustain it. Through the lens of an âIâ and âweâ framework introduced in the paper and the use of a professional doctorate, we discuss how a practitionerâs and professionâs values may be in tension. An example might be found by turning to the field of law, where justice and human rights may be lost beneath weighty procedure and expensive entry costs. The paper seeks an understanding of the different personal and collective ontological stances and tensions that practitioners may experience as they progress through their careers, attempting to align their own values with those of the collective values within their profession. We explore this through a Heideggerian reading of transdisciplinarity
OGLE16aaa - a Signature of a Hungry Super Massive Black Hole
We present the discovery and first three months of follow-up observations of
a currently on-going unusual transient detected by the OGLE-IV survey, located
in the centre of a galaxy at redshift z=0.1655. The long rise to absolute
magnitude of -20.5 mag, slow decline, very broad He and H spectral features
make OGLE16aaa similar to other optical/UV Tidal Disruption Events (TDEs). Weak
narrow emission lines in the spectrum and archival photometric observations
suggest the host galaxy is a weak-line Active Galactic Nucleus (AGN), which has
been accreting at higher rate in the past. OGLE16aaa, along with SDSS J0748,
seems to form a sub-class of TDEs by weakly or recently active super-massive
black holes (SMBHs). This class might bridge the TDEs by quiescent SMBHs and
flares observed as "changing-look QSOs", if we interpret the latter as TDEs. If
this picture is true, the previously applied requirement for identifying a
flare as a TDE that it had to come from an inactive nucleus, could be leading
to observational bias in TDE selection, thus affecting TDE-rate estimations.Comment: Accepted in MNRAS Letter
High-resolution emission spectroscopy retrievals of MASCARA-1b with CRIRES+: Strong detections of CO, HO and Fe emission lines and a CO consistent with solar
The characterization of exoplanet atmospheres has proven to be successful
using high-resolution spectroscopy. Phase curve observations of hot/ultra-hot
Jupiters can reveal their compositions and thermal structures, thereby allowing
the detection of molecules and atoms in the planetary atmosphere using the
cross-correlation technique. We present pre-eclipse observations of the
ultra-hot Jupiter, MASCARA-1b, observed with the recently upgraded CRIRES+
high-resolution infrared spectrograph at the VLT. We report a detection of (8.3) in the K-band and confirm previous detections of
(>15) and (>10) in the day-side atmosphere
of MASCARA-1b. Using a Bayesian inference framework, we retrieve the abundances
of the detected species and constrain planetary orbital velocities, -
profiles, and the carbon-to-oxygen ratio (). A free retrieval results
in an elevated abundance (() =
), leading to a super-solar ratio. More
realistically, allowing for vertically-varying chemistry in the atmosphere by
incorporating a chemical-equilibrium model results in a of
and a metallicity of ,
both consistent with solar values. Finally, we also report a slight offset of
the feature in both K and v that could be a
signature of atmospheric dynamics. Due to the 3D structure of exoplanet
atmospheres and the exclusion of time/phase dependence in our 1D forward
models, further follow-up observations and analysis are required to confirm or
refute this result.Comment: 21 pages, 18 figures, 4 tables, accepted for publication in Monthly
Notices of the Royal Astronomical Societ
Probing the progenitors of Type Ia supernovae using circumstellar material interaction signatures
This work aims to study different probes of Type Ia supernova (SN Ia) progenitors that have been suggested to be linked to the presence of circumstellar material (CSM). In particular, we have investigated, for the first time, the link between narrow blueshifted Na i D absorption profiles and the presence and strength of the broad high-velocity Ca ii near-infrared triplet absorption features seen in SNe Ia around maximum light. With the probes exploring different distances from the SN; Na i D > 1017cm, high-velocity Ca ii features < 1015cm. For this, we have used a new intermediate-resolution X-shooter spectral sample of 15 SNe Ia. We do not identify a link between these two probes, implying either that, one (or both) is not physically related to the presence of CSM or that the occurrence of CSM at the distance explored by one probe is not linked to its presence at the distance probed by the other. However, the previously identified statistical excess in the presence of blueshifted (over redshifted) Na i D absorption is confirmed in this sample at high significance and is found to be stronger in SNe Ia hosted by late-type galaxies. This excess is difficult to explain as being from an interstellar-medium origin as has been suggested by some recent modelling, as such an origin is not expected to show a bias for blueshifted absorption. However, a circumstellar origin for these features also appears unsatisfactory based on our new results, given the lack of link between the two probes of CSM investigated
The Rising Light Curves of Type Ia Supernovae
We present an analysis of the early, rising light curves of 18 Type Ia
supernovae (SNe Ia) discovered by the Palomar Transient Factory (PTF) and the
La Silla-QUEST variability survey (LSQ). We fit these early data flux using a
simple power-law to determine the time of first
light , and hence the rise-time from first light to
peak luminosity, and the exponent of the power-law rise (). We find a mean
uncorrected rise time of days, with individual SN rise-times
ranging from to days. The exponent n shows significant
departures from the simple 'fireball model' of (or ) usually assumed in the literature. With a mean value of , our data also show significant diversity from event to event. This
deviation has implications for the distribution of 56Ni throughout the SN
ejecta, with a higher index suggesting a lesser degree of 56Ni mixing. The
range of n found also confirms that the 56Ni distribution is not standard
throughout the population of SNe Ia, in agreement with earlier work measuring
such abundances through spectral modelling. We also show that the duration of
the very early light curve, before the luminosity has reached half of its
maximal value, does not correlate with the light curve shape or stretch used to
standardise SNe Ia in cosmological applications. This has implications for the
cosmological fitting of SN Ia light curves.Comment: 19 pages, 19 figures, accepted for publication in MNRA
Management of major depression in outpatients attending a cancer centre: a preliminary evaluation of a multicomponent cancer nurse-delivered intervention
A novel nurse-delivered multicomponent intervention for major depressive disorder (MDD) in cancer outpatients was compared with usual care alone in a nonrandomised matched group design (n=30 per group). At the final 6-month outcome, 38.5% (95% CI, 5.4-57%) fewer patients in the intervention group still met the criteria for MDD
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