101 research outputs found
Genetic diversity of selected genes that are potentially economically important in feral sheep of New Zealand
Background: Feral sheep are considered to be a source of genetic variation that has been lost from their
domestic counterparts through selection.
Methods: This study investigates variation in the genes KRTAP1-1, KRT33, ADRB3 and DQA2 in Merino-like feral
sheep populations from New Zealand and its offshore islands. These genes have previously been shown to
influence wool, lamb survival and animal health.
Results: All the genes were polymorphic, but no new allele was identified in the feral populations. In some of
these populations, allele frequencies differed from those observed in commercial Merino sheep and other breeds
found in New Zealand. Heterozygosity levels were comparable to those observed in other studies on feral sheep.
Our results suggest that some of the feral populations may have been either inbred or outbred over the duration
of their apparent isolation.
Conclusion: The variation described here allows us to draw some conclusions about the likely genetic origin of
the populations and selective pressures that may have acted upon them, but they do not appear to be a source of
new genetic material, at least for these four genes.This research was supported by the Brian Mason Scientific and Technical
Trust
Models of organometallic complexes for optoelectronic applications
Organometallic complexes have potential applications as the optically active
components of organic light emitting diodes (OLEDs) and organic photovoltaics
(OPV). Development of more effective complexes may be aided by understanding
their excited state properties. Here we discuss two key theoretical approaches
to investigate these complexes: first principles atomistic models and effective
Hamiltonian models. We review applications of these methods, such as,
determining the nature of the emitting state, predicting the fraction of
injected charges that form triplet excitations, and explaining the sensitivity
of device performance to small changes in the molecular structure of the
organometallic complexes.Comment: To appear in themed issue of J. Mat. Chem. on the modelling of
material
Improving the quality of wool through the use of gene markers
________________________________________________________________________________ Abstract This study aimed at identifying gene markers associated with wool quality traits in Merino and Merino Cross sheep using a candidate gene approach. Polymerase chain reaction-single strand conformational polymorphism (PCR-SSCP) analysis was used to identify sequence variation in the KAP1.3 and K33 genes, while agarose gel electrophoresis was used to detect length variation in the KAP1.1 gene. Two half-sib families (SL1 and SL2) were created for analysis and wool samples were collected from the mid-side region of the SL1 progeny at 12, 24 and 36 months of age, and of the SL2 progeny at 12 months of age. The association of alleles was analysed for each year of phenotypic data by an analysis of variance (ANOVA) tests, using SPSS® version 15. Analysis of each of KAP1.1, KAP1.3 and K33 genes revealed potential gene markers to select for animals with increased staple length, increased staple strength, higher yield, whiter and brighter wool. The results obtained are consistent with KAP1.1, KAP1.3 and KRT1.2 being clustered on one chromosome. Results also indicated that the keratin genes on chromosome 11 are recombining relatively frequently at recombination "hotspots". It appears as though genes coding for the KRTs and KAPs have the potential to impact on wool quality and could potentially be exploited in gene marker-assisted selection programmes in the wool industry for the rapid conversion of wool from one type to another _______________________________________________________________________________
Presence of Middle Cerebellar Peduncle Sign in FMR1 Premutation Carriers Without Tremor and Ataxia
Here we report five cases of male FMR1 premutation carriers who present without clinical symptoms of the fragile X-associated tremor/ataxia syndrome (FXTAS), but who on MRI demonstrate white matter hyperintensities in the middle cerebellar peduncles (MCP sign) and other brain regions, a rare finding. MCP sign is the major radiological feature of FXTAS; it is therefore remarkable to identify five cases in which this MRI finding is present in the absence of tremor and ataxia, the major clinical features of FXTAS. Subjects underwent a detailed neurological evaluation, neuropsychological testing, molecular testing, and MRI evaluation utilizing T2 imaging described here. Additional white matter disease was present in the corpus callosum in four of the five cases. However, all cases were asymptomatic for motor signs of FXTAS
First LIGO search for gravitational wave bursts from cosmic (super)strings
We report on a matched-filter search for gravitational wave bursts from
cosmic string cusps using LIGO data from the fourth science run (S4) which took
place in February and March 2005. No gravitational waves were detected in 14.9
days of data from times when all three LIGO detectors were operating. We
interpret the result in terms of a frequentist upper limit on the rate of
gravitational wave bursts and use the limits on the rate to constrain the
parameter space (string tension, reconnection probability, and loop sizes) of
cosmic string models.Comment: 11 pages, 3 figures. Replaced with version submitted to PR
All-sky LIGO Search for Periodic Gravitational Waves in the Early S5 Data
We report on an all-sky search with the LIGO detectors for periodic
gravitational waves in the frequency range 50--1100 Hz and with the frequency's
time derivative in the range -5.0E-9 Hz/s to zero. Data from the first eight
months of the fifth LIGO science run (S5) have been used in this search, which
is based on a semi-coherent method (PowerFlux) of summing strain power.
Observing no evidence of periodic gravitational radiation, we report 95%
confidence-level upper limits on radiation emitted by any unknown isolated
rotating neutron stars within the search range. Strain limits below 1.E-24 are
obtained over a 200-Hz band, and the sensitivity improvement over previous
searches increases the spatial volume sampled by an average factor of about 100
over the entire search band. For a neutron star with nominal equatorial
ellipticity of 1.0E-6, the search is sensitive to distances as great as 500
pc--a range that could encompass many undiscovered neutron stars, albeit only a
tiny fraction of which would likely be rotating fast enough to be accessible to
LIGO. This ellipticity is at the upper range thought to be sustainable by
conventional neutron stars and well below the maximum sustainable by a strange
quark star.Comment: 6 pages, 1 figur
Stacked Search for Gravitational Waves from the 2006 SGR 1900+14 Storm
We present the results of a LIGO search for short-duration gravitational
waves (GWs) associated with the 2006 March 29 SGR 1900+14 storm. A new search
method is used, "stacking'' the GW data around the times of individual
soft-gamma bursts in the storm to enhance sensitivity for models in which
multiple bursts are accompanied by GW emission. We assume that variation in the
time difference between burst electromagnetic emission and potential burst GW
emission is small relative to the GW signal duration, and we time-align GW
excess power time-frequency tilings containing individual burst triggers to
their corresponding electromagnetic emissions. We use two GW emission models in
our search: a fluence-weighted model and a flat (unweighted) model for the most
electromagnetically energetic bursts. We find no evidence of GWs associated
with either model. Model-dependent GW strain, isotropic GW emission energy
E_GW, and \gamma = E_GW / E_EM upper limits are estimated using a variety of
assumed waveforms. The stacking method allows us to set the most stringent
model-dependent limits on transient GW strain published to date. We find E_GW
upper limit estimates (at a nominal distance of 10 kpc) of between 2x10^45 erg
and 6x10^50 erg depending on waveform type. These limits are an order of
magnitude lower than upper limits published previously for this storm and
overlap with the range of electromagnetic energies emitted in SGR giant flares.Comment: 7 pages, 3 figure
Utilisation of an operative difficulty grading scale for laparoscopic cholecystectomy
Background
A reliable system for grading operative difficulty of laparoscopic cholecystectomy would standardise description of findings and reporting of outcomes. The aim of this study was to validate a difficulty grading system (Nassar scale), testing its applicability and consistency in two large prospective datasets.
Methods
Patient and disease-related variables and 30-day outcomes were identified in two prospective cholecystectomy databases: the multi-centre prospective cohort of 8820 patients from the recent CholeS Study and the single-surgeon series containing 4089 patients. Operative data and patient outcomes were correlated with Nassar operative difficultly scale, using Kendall’s tau for dichotomous variables, or Jonckheere–Terpstra tests for continuous variables. A ROC curve analysis was performed, to quantify the predictive accuracy of the scale for each outcome, with continuous outcomes dichotomised, prior to analysis.
Results
A higher operative difficulty grade was consistently associated with worse outcomes for the patients in both the reference and CholeS cohorts. The median length of stay increased from 0 to 4 days, and the 30-day complication rate from 7.6 to 24.4% as the difficulty grade increased from 1 to 4/5 (both p < 0.001). In the CholeS cohort, a higher difficulty grade was found to be most strongly associated with conversion to open and 30-day mortality (AUROC = 0.903, 0.822, respectively). On multivariable analysis, the Nassar operative difficultly scale was found to be a significant independent predictor of operative duration, conversion to open surgery, 30-day complications and 30-day reintervention (all p < 0.001).
Conclusion
We have shown that an operative difficulty scale can standardise the description of operative findings by multiple grades of surgeons to facilitate audit, training assessment and research. It provides a tool for reporting operative findings, disease severity and technical difficulty and can be utilised in future research to reliably compare outcomes according to case mix and intra-operative difficulty
Search for High Frequency Gravitational Wave Bursts in the First Calendar Year of LIGO's Fifth Science Run
We present an all-sky search for gravitational waves in the frequency range 1
to 6 kHz during the first calendar year of LIGO's fifth science run. This is
the first untriggered LIGO burst analysis to be conducted above 3 kHz. We
discuss the unique properties of interferometric data in this regime. 161.3
days of triple-coincident data were analyzed. No gravitational events above
threshold were observed and a frequentist upper limit of 5.4 events per year on
the rate of strong gravitational wave bursts was placed at a 90% confidence
level. Implications for specific theoretical models of gravitational wave
emission are also discussed.Comment: 13 pages, accepted for publication in Physical Review
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