57 research outputs found
The sub-millimetre evolution of V4334 Sgr (Sakurai's Object)
We report the results of monitoring of V4334 Sgr (Sakurai's Object) at 450
microns and 850 microns with SCUBA on the James Clerk Maxwell Telescope. The
flux density at both wavelengths has increased dramatically since 2001, and is
consistent with continued cooling of the dust shell in which Sakurai's Object
is still enshrouded, and which still dominates the near-infrared emission.
Assuming that the dust shell is optically thin at sub-millimetre wavelengths
and optically thick in the near-infrared, the sub-millimetre data imply a
mass-loss rate during 2003 of ~3.4(+/0.2)E-5 for a gas-to-dust ratio of 75.
This is consistent with the evidence from 1-5micron observations that the
mass-loss is steadily increasing.Comment: 5 pages, 4 eps figures, accepted for publication in MNRA
Infrared spectroscopy of Nova Cassiopeiae 1993 (V705 Cas). IV. A closer look at the dust
Nova Cassiopeiae 1993 (V705 Cas) was an archetypical dust-forming nova. It
displayed a deep minimum in the visual light curve, and spectroscopic evidence
for carbon, hydrocarbon and silicate dust. We report the results of fitting the
infrared spectral energy distribution with the DUSTY code, which we use to
determine the properties and geometry of the emitting dust. The emission is
well described as originating in a thin shell whose dust has a carbon:silicate
ratio of ~2:1 by number (1.26:1 by mass) and a relatively flat size
distribution. The 9.7micron and 18micron silicate features are consistent with
freshly-condensed dust and, while the lower limit to the grain size
distribution is not well constrained, the largest grains have dimensions
\~0.06micron; unless the grains in V705 Cas were anomalously small, the sizes
of grains produced in nova eruptions may previously have been overestimated in
novae with optically thick dust shells. Laboratory work by Grishko & Duley may
provide clues to the apparently unique nature of nova UIR features.Comment: 11 pages, 9 fugure
Silicate dust in the environment of RS Ophiuchi following the 2006 eruption
We present further Spitzer Space Telescope observations of the recurrent nova
RS Ophiuchi, obtained over the period 208-430 days after the 2006 eruption. The
later Spitzer IRS data show that the line emission and free-free continuum
emission reported earlier is declining, revealing incontrovertible evidence for
the presence of silicate emission features at 9.7 and 18microns. We conclude
that the silicate dust survives the hard radiation impulse and shock blast wave
from the eruption. The existence of the extant dust may have significant
implications for understanding the propagation of shocks through the red giant
wind and likely wind geometry.Comment: 12 pages, 4 figures, accepted for publication in ApJ (Letters
The Spitzer IRS view of V4334 Sgr (Sakurai's Object)
We present an observation of the very late thermal pulse object V4334 Sgr
(Sakurai's Object) with the Infrared Spectrometer (IRS) on the Spitzer Space
Telescope. The emission from 5-38 microns is dominated by the still-cooling
dust shell. A number of features are seen in absorption against the dust shell,
which we attribute to HCN and polyyne molecules. We use these features to
determine the 12C/13C ratio for the absorbing gas to be ~ 3.2 (+3.2,-1.6}; this
implies that, despite the H-content of the molecules, the hydrocarbon-bearing
gas must have originated in material produced in the very late thermal pulse.
We see no evidence of emission lines, despite the recently-reported optical and
radio observations that suggest the effective temperature of the stellar
remnant is rising.Comment: 5 pages, 6 figures. Accepted for publication in MNRA
Genetic determinants of telomere length from 109,122 ancestrally diverse whole-genome sequences in TOPMed
Genetic studies on telomere length are important for understanding age-related diseases. Prior GWAS for leukocyte TL have been limited to European and Asian populations. Here, we report the first sequencing-based association study for TL across ancestrally-diverse individuals (European, African, Asian and Hispanic/Latino) from the NHLBI Trans-Omics for Precision Medicine (TOPMed) program. We used whole genome sequencing (WGS) of whole blood for variant genotype calling and the bioinformatic estimation of telomere length in n=109,122 individuals. We identified 59 sentinel variants (p-value OBFC1indicated the independent signals colocalized with cell-type specific eQTLs for OBFC1 (STN1). Using a multi-variant gene-based approach, we identified two genes newly implicated in telomere length, DCLRE1B (SNM1B) and PARN. In PheWAS, we demonstrated our TL polygenic trait scores (PTS) were associated with increased risk of cancer-related phenotypes
Outcomes from elective colorectal cancer surgery during the SARS-CoV-2 pandemic
This study aimed to describe the change in surgical practice and the impact of SARS-CoV-2 on mortality after surgical resection of colorectal cancer during the initial phases of the SARS-CoV-2 pandemic
Comprehensive molecular, genomic and phenotypic analysis of a major clone of Enterococcus faecalis MLST ST40
A mobile game world for MÄori language learning : a thesis presented in partial fulfilment of the requirements for the degree of Master of Information Sciences at Massey University, Albany Campus, Auckland, New Zealand
This project involves the research, development and evaluation of a mobile assisted language learning tool that teaches some aspects of the Maori language within a virtual game world. The Maori language has been going through a process of rejuvenation since the mid-1900s. A wide range of multimedia resources have been created to support the process of language rejuvenation and there have been some effective digital resources created. Despite the ubiquity of modern games, computer games are a form of media that is under-represented in the wealth of Maori language resources and there are only a small handful of existing software tools for Maori language learning, of which few are game based.
There is growing interest in the application of modern game mechanics to other areas; popularly termed as gamification. This project aims to use the more dynamic features of modern games within a simulated game world to structure Maori language learning experiences. While globally there have been many computer assisted language learning tools and there is some research on virtual worlds and language learning, there have been few language learning tools developed within purpose built simulated game worlds.
The project is structured around the Design Science Research Process in which short iterative design cycles are applied to the development phase with prototypes being developed and tested with teachers, students and academics as design partners. The implementation of techniques in human centred design ensures that design partners are involved in the whole design and research process. In practice this involved testing early prototypes with educators then subsequently whole classes of students. In between testing the software was redeveloped based on the observations and feedback collected
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