355 research outputs found
The evaluation of tropical legumes for use in ley pastures in central and southern Queensland
Soil fertility decline in the northern grain belt has resulted in corresponding declines in grain yield and quality. One option to overcome this decline is through the incorporation of ley or phase pastures into the cropping system. A range of tropical species are currently being evaluated as either self-regenerating annuals or perennial ley pasture legumes for central (CQ) and southern (SQ) Queensland. Several new accessions have regenerated from seedlings and may provide self -regenerating annuals for use as ley legumes. C. pascuorum has consistently been a high yielding accession in both CQ and SQ and has the ability to regenerate strongly from seed. Other accessions which are promising as regenerating annuals include V. oblongifolia CPI 121699. The most outstanding perennial species was M. bracteatum and within that species, CPI 55769 was the most promising. Other strongly persisting species were D. virgatus, C. ternatea and M. atropurpureum. Further studies are now being undertaken to develop management options for the most promising of these legumes
Simulation of Lablab Pastures
The potential of legume-based pastures to address declining soil nitrogen on marginal cropping soils is increasingly recognised in northern Australia, as such there is a need for cost benefit analysis of pastures and crops in a mixed farming system. In highly variable rainfall environments, biophysical modelling may be the best way of identifying and quantifying interactions with mixed crop-livestock systems on a seasonal basis. This paper describes a case study where both animal productivity and lablab pasture production is simulated. Lablab (Lablab purpureus) is an annual tropical legume widely used as a short-term legume phase in crop-pasture rotations, providing high quality forage for animal production and a low risk nitrogen input for crop production
Theoretical He I Emissivities in the Case B Approximation
We calculate the He I case B recombination cascade spectrum using improved
radiative and collisional data. We present new emissivities over a range of
electron temperatures and densities. The differences between our results and
the current standard are large enough to have a significant effect not only on
the interpretation of observed spectra of a wide variety of objects but also on
determinations of the primordial helium abundance.Comment: Accepted to ApJ
WHAM Observations of H-alpha from High-Velocity Clouds: Are They Galactic or Extragalactic?
It has been suggested that high velocity clouds may be distributed throughout
the Local Group and are therefore not in general associated with the Milky Way
galaxy. With the aim of testing this hypothesis, we have made observations in
the H-alpha line of high velocity clouds selected as the most likely candidates
for being at larger than average distances. We have found H-alpha emission from
4 out of 5 of the observed clouds, suggesting that the clouds under study are
being illuminated by a Lyman continuum flux greater than that of the
metagalactic ionizing radiation. Therefore, it appears likely that these clouds
are in the Galactic halo and not distributed throughout the Local Group.Comment: 12 pages, 5 eps figures, accepted for publication in ApJ Letter
An evaluation of staff experiences of the Royal Literary Fund writer-in-residence service to support improvements in written communication in healthcare
Written communication is essential to staff and patient experience in healthcare. The Royal Literary Fund has hosted a writing fellow in an NHS Trust since 2018 providing professional writing training. The aim of this evaluation was to explore the experiences of staff using the service. Semi-structured interviews were conducted with 21 staff members from a range of professions who had accessed the service. Data were analysed using thematic analysis. Findings: The writing service was highly valued. Three themes emerged: feelings about writing at work, reported benefits of attending sessions, and perceived barriers to accessing them. Staff felt underskilled in professional writing and described the wish to write more succinctly and reflectively. Self-reported confidence increased after sessions. Stigma around writing skills prevented some staff from recommending the service. Wider adoption of professional writing skills training through the NHS could have benefits in terms of increasing self-perceived skills and confidence
Accurate Hydrogen Spectral Simulations with a Compact Model Atom
Many large scale numerical simulations of astrophysical plasmas must also
reproduce the hydrogen ionization and the resulting emission spectrum, in some
cases quite accurately. We describe a compact model hydrogen atom that can be
readily incorporated into such simulations. It reproduces the recombination
efficiency and line spectrum predicted by much larger calculations for a very
broad range of densities and temperatures. Uncertainties in hydrogen collision
data are the largest source of differences between our compact atom and
predictions of more extensive calculations, and underscore the need for
accurate atomic data.Comment: 18 pages, prepared in MS-Word, Postscript only, 12 Figures, also
available at http://www.pa.uky.edu/~ferguson/bib/bib.html, accepted for
publication in the Astrophysical Journa
Radiation from early black holes - I: effects on the neutral inter-galactic medium
In the pre-reionization Universe, the regions of the inter-galactic medium
(IGM) which are far from luminous sources are the last to undergo reionization.
Until then, they should be scarcely affected by stellar radiation; instead, the
X-ray emission from an early black hole (BH) population can have much larger
influence. We investigate the effects of such emission, looking at a number of
BH model populations (differing for the cosmological density evolution of BHs,
the BH properties, and the spectral energy distribution of the BH emission). We
find that BH radiation can easily heat the IGM to 10^3-10^4 K, while achieving
partial ionization. The most interesting consequence of this heating is that
BHs are expected to induce a 21-cm signal (delta T_b ~ 20-30 mK at z<~12) which
should be observable with forthcoming experiments (e.g. LOFAR). We also find
that at z<~10 BH emission strongly increases the critical mass separating
star-forming and non-star-forming halos.Comment: 17 pages, 14 figures; accepted for publication on MNRA
Photoevaporation of Protoplanetary Disks
We present HST/NICMOS Paschen alpha images and low and high resolution IRS
spectra of photoevaporating disk-tail systems originally detected at 24 micron
near O stars. We find no Paschen alpha emission in any of the systems. The
resulting upper limits correspond to about 0.000002-0.000003 solar mass of mass
in hydrogen in the tails suggesting that the gas is severely depleted. The IRAC
data and the low resolution 5-12 micron IRS spectra provide evidence for an
inner disk while high resolution long wavelength (14-30 micron) IRS spectra
confirm the presence of a gas free ``tail'' that consists of ~ 0.01 to ~ 1
micron dust grains originating in the outer parts of the circumstellar disks.
Overall our observations support theoretical predictions in which
photoevaporation removes the gas relatively quickly (<= 100000 yrs) from the
outer region of a protoplanetary disk but leaves an inner more robust and
possibly gas-rich disk component of radius 5-10 AU. With the gas gone, larger
solid bodies in the outer disk can experience a high rate of collisions and
produce elevated amounts of dust. This dust is being stripped from the system
by the photon pressure of the O star to form a gas-free dusty tail.Comment: 9 pages 5 figures, accepted for publication in Ap
Mutations specific to the Rac-GEF domain of <i>TRIO</i> cause intellectual disability and microcephaly
Background: Neurodevelopmental disorders have challenged clinical genetics for decades, with over 700 genes implicated and many whose function remains unknown. The application of whole-exome sequencing is proving pivotal in closing the genotype/phenotype gap through the discovery of new genes and variants that help to unravel the pathogenic mechanisms driving neuropathogenesis. One such discovery includes TRIO, a gene recently implicated in neurodevelopmental delay. Trio is a Dbl family guanine nucleotide exchange factor (GEF) and a major regulator of neuronal development, controlling actin cytoskeleton dynamics by activating the GTPase Rac1.Methods: Whole-exome sequencing was undertaken on a family presenting with global developmental delay, microcephaly and mild dysmorphism. Father/daughter exome analysis was performed, followed by confirmatory Sanger sequencing and segregation analysis on four individuals. Three further patients were recruited through the deciphering developmental disorders (DDD) study. Functional studies were undertaken using patient-specific Trio protein mutations.Results: We identified a frameshift deletion in TRIO that segregated autosomal dominantly. By scrutinising data from DDD, we further identified three unrelated children with a similar phenotype who harboured de novo missense mutations in TRIO. Biochemical studies demonstrated that in three out of four families, the Trio mutations led to a markedly reduced Rac1 activation.Conclusions: We describe an inherited global developmental delay phenotype associated with a frameshift deletion in TRIO. Additionally, we identify pathogenic de novo missense mutations in TRIO associated with the same consistent phenotype, intellectual disability, microcephaly and dysmorphism with striking digital features. We further functionally validate the importance of the GEF domain in Trio protein function. Our study demonstrates how genomic technologies are yet again proving prolific in diagnosing and advancing the understanding of neurodevelopmental disorders.<br/
A New Observational Upper Limit to the Low Redshift Ionizing Background Radiation
We report a new Fabry-Perot search for Halpha emission from the intergalactic
cloud HI 1225+01 in an attempt to measure the low redshift ionizing background
radiation. We set a new 2 sigma upper limit on Halpha emission of 8 mR (5 x
10^{-20} ergs cm^{-2} s^{-1} arcsec^{-2}). Conversion of this limit to limits
on the strength of the ionizing background requires knowledge of the ratio of
the projected to total surface area of this cloud, which is uncertain. We
discuss the plausible range of this ratio, and within this range find that the
strength of the ionizing backround is in the lower range of, but consistent
with, previous observational and theoretical estimates.Comment: 46 pages including 9 figures (7 ps, 2 gif
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