3,212 research outputs found
From educational policy issues to specific research questions and the basic elements of research design
This module concentrates on such decision-oriented research, and seeks to help researchers identify important issues needing attention, through a systematic ‘mapping’ of the educational territory. It then proceeds to find ways to establish priorities, using a consensus-building approach to select projects from the infinite number of problems which exist ‘out there’. Finally it comes down to specifics, with a discussion of ways to develop specific aims from general aims, and operationalize these through the use of research questions and hypotheses. The last section gives some illustrations of exactly how this can be carried out in a systematic way
Targeting Amino Acid Metabolic Vulnerabilities in Myeloid Malignancies
Tumor cells require a higher supply of nutrients for growth and proliferation than normal cells. It is well established that metabolic reprograming in cancers for increased nutrient supply exposes a host of targetable vulnerabilities. In this article we review the documented changes in expression patterns of amino acid metabolic enzymes and transporters in myeloid malignancies and the growing list of small molecules and therapeutic strategies used to disrupt amino acid metabolic circuits within the cell. Pharmacological inhibition of amino acid metabolism is effective in inducing cell death in leukemic stem cells and primary blasts, as well as in reducing tumor burden in in vivo murine models of human disease. Thus targeting amino acid metabolism provides a host of potential translational opportunities for exploitation to improve the outcomes for patients with myeloid malignancies
X-ray and Radio Timing of the Pulsar in 3C 58
We present timing data spanning 6.4 yr for the young and energetic PSR
J0205+6449, in the supernova remnant 3C 58. Data were obtained with the Rossi
X-ray Timing Explorer, the Jodrell Bank Observatory and the Green Bank
Telescope. We present phase-coherent timing analyses showing timing noise and
two spin-up glitches with fractional frequency increases of ~3.4E-7 near MJD
52555, and ~3.8E-6 between MJDs 52777 and 53062. These glitches are unusually
large if the pulsar was created in the historical supernova in 1181 as has been
suggested. For the X-ray timing we developed a new unbinned maximum-likelihood
method for determining pulse arrival times which performs significantly better
than the traditional binned techniques. In addition, we present an X-ray pulse
profile analysis of four years of RXTE data showing that the pulsar is detected
up to ~40 keV. We also present the first measurement of the phase offset
between the radio and X-ray pulse for this source, showing that the radio pulse
leads the X-ray pulse by phi=0.10+/-0.01 in phase. We compile all known
measurements of the phase offsets between radio and X-ray and radio and
gamma-ray pulses for X-ray and gamma-ray pulsars. We show that there is no
relationship between pulse period and phase offset, supported by our
measurement of the phase offset for PSR J0205+6449.Comment: 19 pages, 12 figures. Published in the Astrophysical Journal.
Includes additional data analysis and two new figure
Study of Four Young TeV Pulsar Wind Nebulae with a Spectral Evolution Model
We study four young Pulsar Wind Nebulae (PWNe) detected in TeV gamma-rays,
G21.5-0.9, G54.1+0.3, Kes 75, and G0.9+0.1, using the spectral evolution model
developed and applied to the Crab Nebula in our previous work. We model the
evolution of magnetic field and particle distribution function inside a
uniformly expanding PWN considering a time-dependent injection from the pulsar
and radiative and adiabatic losses. Considering uncertainties in the
interstellar radiation field (ISRF) and their distance, we study two cases for
each PWN. Because TeV PWNe have a large TeV gamma-rays to X-rays flux ratio,
the magnetic energy of the PWNe accounts for only a small fraction of the total
energy injected (typically a few x 10^{-3}). The gamma-ray emission is
dominated by inverse Compton scattering off the infrared photons of the ISRF. A
broken power-law distribution function for the injected particles reproduces
the observed spectrum well, except for G0.9+0.1. For G0.9+0.1, we do not need a
low energy counterpart because adiabatic losses alone are enough to reproduce
the radio observations. High energy power-law indices at injection are similar
(2.5 -- 2.6), while low energy power-law indices range from 1.0 to 1.6. The
lower limit of the particle injection rate indicates that the pair multiplicity
is larger than 10^4. The corresponding upper limit of the bulk Lorentz factor
of the pulsar winds is close to the break energy of the broken power-law
injection, except for Kes 75.Comment: Accepted for publication in ApJ; 56pages, 15figure
The glitch-induced identity changes of PSR J1119-6127
We demonstrate that the high-magnetic field pulsar J1119-6127 exhibits three
different types of behaviour in the radio band. Trailing the "normal" profile
peak there is an "intermittent" peak and these components are flanked by two
additional components showing very erratic "RRAT-like" emission. Both the
intermittent and RRAT-like events are extremely rare and are preceded by a
large amplitude glitch in the spin-down parameters. The post-glitch spin-down
rate is smaller than the pre-glitch rate. This type of relaxation is very
unusual for the pulsar population as a whole, but is observed in the glitch
recovery of a RRAT. The abnormal emission behaviour in PSR J1119-6127 was
observed up to three months after the epoch of the large glitch, suggestive of
changes in the magnetospheric conditions during the fast part of the recovery
process. We argue that both the anomalous recoveries and the emission changes
could be related to reconfigurations of the magnetic field. Apart from the
glitches, the spin-down of PSR J1119-6127 is relatively stable, allowing us to
refine the measurement of the braking index (n=2.684\pm0.002) using more than
12 years of timing data. The properties of this pulsar are discussed in light
of the growing evidence that RRATs do not form a distinct class of pulsar, but
rather are a combination of different extreme emission types seen in other
neutron stars. Different sub-classes of the RRATs can potentially be separated
by calculating the lower limit on the modulation index of their emission. We
speculate that if the abnormal behaviour in PSR J1119-6127 is indeed glitch
induced then there might exist a population of neutron stars which only become
visible in the radio band for a short duration in the immediate aftermath of
glitch activity. These neutron stars will be visible in the radio band as
sources that only emit some clustered pulses every so many years.Comment: 20 pages, 10 figures, Accepted for publication in MNRA
X-ray observations of the Large Magellanic Cloud pulsar PSR B0540-69 and its PWN
PSR B0540-69 is a young pulsar in the Large Magellanic Cloud that has similar
properties with respect to the Crab Pulsar, and is embedded in a Pulsar Wind
Nebula. We have analyzed the complete archival RXTE dataset of observations of
this source, together with new Swift-XRT and INTEGRAL-IBIS data. Accurate
lightcurves are produced in various energy bands between 2 and 60 keV, showing
no significant energy variations of the pulse shape. The spectral analysis
shows that the pulsed spectrum is curved, and is best fitted up to 100 keV by a
log-parabolic model: this strengthens the similarities with the Crab pulsar,
and is discussed in the light of a phenomenologic multicomponent model. The
total emission from this source is studied, the relative contributions of the
pulsar and the PWN emission are derived, and discussed in the context of other
INTEGRAL detected pulsar/PWN systems.Comment: 11 pages, 11 figures. Accepted for publication in MNRA
How Crowd Worker Factors Influence Subjective Annotations: A Study of Tagging Misogynistic Hate Speech in Tweets
Crowdsourced annotation is vital to both collecting labelled data to train
and test automated content moderation systems and to support human-in-the-loop
review of system decisions. However, annotation tasks such as judging hate
speech are subjective and thus highly sensitive to biases stemming from
annotator beliefs, characteristics and demographics. We conduct two
crowdsourcing studies on Mechanical Turk to examine annotator bias in labelling
sexist and misogynistic hate speech. Results from 109 annotators show that
annotator political inclination, moral integrity, personality traits, and
sexist attitudes significantly impact annotation accuracy and the tendency to
tag content as hate speech. In addition, semi-structured interviews with nine
crowd workers provide further insights regarding the influence of subjectivity
on annotations. In exploring how workers interpret a task - shaped by complex
negotiations between platform structures, task instructions, subjective
motivations, and external contextual factors - we see annotations not only
impacted by worker factors but also simultaneously shaped by the structures
under which they labour.Comment: Accepted to the 11th AAAI Conference on Human Computation and
Crowdsourcing (HCOMP 2023
But everyone else is doing it: A closer look at the occupational taxpaying culture of one business sector
When individuals embark on their careers they not only become acculturated into their occupational sectors' day-to-day norms and practices, but also their taxpaying ones. Although the research on taxpaying cultures is still in its infancy, understanding more about taxpaying cultures could improve our understanding of the processes underlying tax compliance. To this end, this study aimed to build a detailed picture of the taxpaying culture (i.e. the norms and values) of one business sector—the hairdressing/beauty industry. Nineteen small business and self-employed hairdressers/beauticians were interviewed and a variant of Grounded theory was used to uncover the main themes that ran through the interviews as a whole. The main themes that emerged—which appear to characterize this sector's culture—include a reliance on accountants/tax advisors, the notion of an acceptable level of cash-in-hand payments, and the use of different mental accounts for different types of income. Although some of these themes have already arisen in the small business literature they have often been couched in individualistic terms. We build a case that these issues are more cultural than individual—they are tied to occupational group membership as they are socially constructed within occupational groups and are a key component of the group's taxpaying culture. Implications and directions for future research are discussed
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