252 research outputs found
SN 2016iet: The Pulsational or Pair Instability Explosion of a Low Metallicity Massive CO Core Embedded in a Dense Hydrogen-Poor Circumstellar Medium
We present optical photometry and spectroscopy of SN 2016iet, an
unprecedented Type I supernova (SN) at with no obvious analog in the
existing literature. The peculiar light curve has two roughly equal brightness
peaks ( mag) separated by 100 days, and a subsequent slow decline
by 5 mag in 650 rest-frame days. The spectra are dominated by emission lines of
calcium and oxygen, with a width of only km s, superposed on a
strong blue continuum in the first year, and with a large ratio of at late times. There is no clear evidence
for hydrogen or helium associated with the SN at any phase. We model the light
curves with several potential energy sources: radioactive decay, central
engine, and circumstellar medium (CSM) interaction. Regardless of the model,
the inferred progenitor mass near the end of its life (i.e., CO core mass) is
M and up to M, placing the event in the
regime of pulsational pair instability supernovae (PPISNe) or pair instability
supernovae (PISNe). The models of CSM interaction provide the most consistent
explanation for the light curves and spectra, and require a CSM mass of
M ejected in the final decade before explosion. We further
find that SN 2016iet is located at an unusually large offset ( kpc) from
its low metallicity dwarf host galaxy ( Z, M), supporting the PPISN/PISN interpretation. In the final
spectrum, we detect narrow H emission at the SN location, likely due to
a dim underlying galaxy host or an H II region. Despite the overall consistency
of the SN and its unusual environment with PPISNe and PISNe, we find that the
inferred properties of SN\,2016iet challenge existing models of such events.Comment: 26 Pages, 17 Figures, Submitted to Ap
Research lives of physical education teacher educators
peer-reviewed.This paper aims to provide insights into the research worlds of an international group of mid- and late-career physical education teacher educators. Specifically, it explores participants’ motives for research engagement and choices, and investigates what challenges and facilitates their research efforts. Two rounds of individual in-depth semi-structured interviews were conducted with 14 physical education teacher educators across 7 countries. Findings point to a distinction between research motives. Embarking on formal theses or specific funded projects was often motivated by practical and contextual drivers, such as job requirements or a wish for promotion, and was associated with feelings of frustration and stress. Motives for engaging in research in general, on the other hand, tended to be more personal or altruistic and elicited feelings such as enjoyment and passion. Time constraints, skill gaps and language barriers were all seen as challenges to research endeavours, while learning through doing, seeing and reading, and collaboration with others were seen as the main facilitators.ACCEPTEDpeer-reviewe
The Tidal Disruption Event AT 2018hyz II: Light Curve Modeling of a Partially Disrupted Star
AT 2018hyz (=ASASSN-18zj) is a tidal disruption event (TDE) located in the
nucleus of a quiescent E+A galaxy at a redshift of , first
detected by the All-Sky Automated Survey for Supernovae (ASAS-SN). We present
optical+UV photometry of the transient, as well as an X-ray spectrum and radio
upper limits. The bolometric light curve of AT 2018hyz is comparable to other
known TDEs and declines at a rate consistent with a at early times,
emitting a total radiated energy of erg. An excess bump
appears in the UV light curve about 50 days after bolometric peak, followed by
a flattening beyond 250 days. The light curve shows an excess bump in the UV
about 50 days after bolometric peak lasting for at least 100 days, which may be
related to an outflow. We detect a constant X-ray source present for at least
86 days. The X-ray spectrum shows a total unabsorbed flux of erg cm s and is best fit by a blackbody plus
power-law model with a photon index of . A thermal X-ray model is
unable to account for photons keV, while the radio non-detection favors
inverse-Compton scattering rather than a jet for the non-thermal component. We
model the optical and UV light curves using the Modular Open-Source Fitter for
Transients (MOSFiT) and find a best fit for a black hole of
M partially disrupting a M star (stripping a mass of
M for the inferred impact parameter, ). The low
optical depth implied by the small debris mass may explain how we are able to
see hydrogen emission with disk-like line profiles in the spectra of AT 2018hyz
(see our companion paper, Short et al.~2020).Comment: 10 pages, 10 figures, published in MNRA
Resilience in high-risk adolescents of mothers with recurrent depressive disorder: the contribution of fathers
This study examines the role of paternal emotional support as a resilience promoter in offspring of mothers with depression by considering the role of fathers’ mental health and the quality of the couple relationship. Two hundred and sixty-five mothers with recurrent unipolar depression, partners and adolescents from Wales were assessed. Paternal emotional support, couple relationship quality, and paternal depression were assessed at baseline; adolescent mental health symptoms were assessed using the Child and Adolescent Psychiatric Assessment at follow-up. Results showed evidence of an indirect pathway whereby couple relationship quality predicted paternal emotional support (β=-.21, 95% CI [-.34, -.08]; p=.002) which in turn predicted adolescent depression (β=-.18, 95% CI [-.33, -.04]; p=.02), but not disruptive behaviours (β=-.10, 95% CI [-.26, .40]; p=.21), after controlling for relevant confounders. The findings highlight that fathers and the broader family system play an important role in enhancing resilience to depression symptoms in at-risk adolescents
Multi-Messenger Astronomy with Extremely Large Telescopes
The field of time-domain astrophysics has entered the era of Multi-messenger
Astronomy (MMA). One key science goal for the next decade (and beyond) will be
to characterize gravitational wave (GW) and neutrino sources using the next
generation of Extremely Large Telescopes (ELTs). These studies will have a
broad impact across astrophysics, informing our knowledge of the production and
enrichment history of the heaviest chemical elements, constrain the dense
matter equation of state, provide independent constraints on cosmology,
increase our understanding of particle acceleration in shocks and jets, and
study the lives of black holes in the universe. Future GW detectors will
greatly improve their sensitivity during the coming decade, as will
near-infrared telescopes capable of independently finding kilonovae from
neutron star mergers. However, the electromagnetic counterparts to
high-frequency (LIGO/Virgo band) GW sources will be distant and faint and thus
demand ELT capabilities for characterization. ELTs will be important and
necessary contributors to an advanced and complete multi-messenger network.Comment: White paper submitted to the Astro2020 Decadal Surve
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Understanding potential career changers’ experience of career confidence following a positive psychology based coaching programme
Changes in the labour market over the last decades have led to an increase in the number of career and job changes individuals are likely to face in their working lives. Previous research indicates that a high level of confidence can help individuals to make positive career changes, yet an agreed definition of confidence is not widely accepted, and the literature provides a limited evidence base for practice. This research involved five female participants who were contemplating a career change. They took part in a coaching programme which consisted of four positive psychology interventions based on a proposal of core confidence as a higher order construct composed of self-efficacy, hope, optimism and resilience. Data were gathered through semi-structured interviews and written reflections and an interpretative phenomenological analysis showed that participants perceived their career confidence before the programme as low, incorporating negative affect and self-doubt. After the programme, participants demonstrated increased career engagement, self-awareness and a positive and optimistic outlook. The analysis revealed that change was effected through the development of hope, change in cognitive processes and coaching as a catalyst. Implications for the definition of career confidence, and for positive psychology and career coaching practice are considered
Power and limitations of electrophoretic separations in proteomics strategies
Proteomics can be defined as the large-scale analysis of proteins. Due to the
complexity of biological systems, it is required to concatenate various
separation techniques prior to mass spectrometry. These techniques, dealing
with proteins or peptides, can rely on chromatography or electrophoresis. In
this review, the electrophoretic techniques are under scrutiny. Their
principles are recalled, and their applications for peptide and protein
separations are presented and critically discussed. In addition, the features
that are specific to gel electrophoresis and that interplay with mass
spectrometry (i.e., protein detection after electrophoresis, and the process
leading from a gel piece to a solution of peptides) are also discussed
Adult Consequences of Late Adolescent Alcohol Consumption: A Systematic Review of Cohort Studies
In a systematic review of cohort studies of adolescent drinking and later outcomes, Jim McCambridge and colleagues show that although studies suggest links to worse adult physical and mental health and social consequences, existing evidence is of poor quality
Obstacles, Networking Approaches and Entrepreneurial Network Changes
While recent work has considered network change, little is known about how certain factors determine such changes. This study focuses on two factors – the type of obstacles entrepreneurs face and their networking approach – and employs a two‐stage research design and network visualisation approach to capture entrepreneurs’ experiences in managing networks during their entrepreneurial journey. Using an inductive approach, the first stage of the study identifies the obstacles and networking approaches that influence different types of network changes. The second stage employs a deductive approach to test the hypotheses developed from the first stage using a larger sample. We find that in experiencing obstacles from internal sources, entrepreneurs are more likely to find support from weak ties while strong ties are beneficial for overcoming obstacles from external sources. In having difficulties in acquiring entrepreneurial knowledge and skills, entrepreneurs are more likely to develop a low‐density network consisting of many structural holes. Conversely, dealing with difficulties in accessing market and resources imposes over‐reliance on high‐density network. Furthermore, the entrepreneurs’ networking approaches also influence network changes and partially mediate the relationship between the networks and the obstacles they face
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