342 research outputs found

    The buy-write strategy, index investment and the efficient market hypothesis: more Australian evidence

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    The purpose of this study is to examine the performance of an index buy-write strategy in the using three portfolios based on the Whaley (2002) approach; one for a portfolio of bank bills, one for a benchmark index and the third for a benchmark index hedged by index call options. The study uses Australian daily data between 1991 and 2006 and confirms that the buy-write strategy outperforms the index-only portfolio on both a risk and return basis. In addition, the strategy is seen to produce abnormal returns and therefore provides further evidence that appears to violate the efficient market hypothesis

    Temporal and spatial trends in stranding records of cetaceans on the Irish coast, 2002–2014

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    Using Irish strandings data collected between 2002 and 2014, seasonal and annual trends in the number of strandings for all strandings identified to species level (N ¼ 1480), and for the five most frequently reported species: common dolphin (25.7% of records), harbour porpoise (22.2%), long-finned pilot whale (8.8%), striped dolphin (6.9%) and bottlenose dolphin (6.9%) were investigated. With the exception of bottlenose dolphins, there was a significant linear increase in the number of strandings across years for all species and for all strandings collectively, that were identified to species-level. Only common dolphins demonstrated a significant increase in the proportion of records relative to all other strandings, which may be indicative of a real rise in the number of strandings of this species. Common dolphins and harbour porpoises showed a similar significant difference in monthly strandings, with more strandings occurring during the earlier months of the year.\ud Significant differences in the gender of stranded animals were found in common, striped, bottlenose and Atlantic white-sided dolphins and sperm and pygmy sperm whales. Live and mass stranding events were primarily comprised of pelagic species. Most strandings occurred on the south and west coasts, with two hotspots for live and mass strandings identified. The patterns and trends identified are discussed in relation to the caveats in interpreting strandings data. Specifically to Ireland, the findings highlight the urgent need to build on the current volunteer reporting network and augment this comprehensive dataset with post-mortem examinations to better understand the cause of the trends identified. The importance of strandings data in informing conservation and management guidelines of these species’ is discussed

    The near-infrared excitation of the HH211 protostellar outflow

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    The protostellar outflow HH211 is of considerable interest since it is extremely young and highly collimated. Here, we explore the outflow through imaging and spectroscopy in the near-infrared to determine if there are further diagnostic signatures of youth. We confirm the detection of a near-infrared continuum of unknown origin. We propose that it is emitted by the driving millimeter source, escapes the core through tunnels, and illuminates features aligning the outflow. Narrow-band flux measurements of these features contain an unusually large amount of continuum emission. [Fe II] emission has been detected and is restricted to isolated condensations. However, the characteristics of vibrational excitation of molecular hydrogen resemble those of older molecular outflows. We attempt to model the ordered structure of the western outflow as a series of shocks, finding that bow shocks with J-type dissociative apices and C-type flanks are consistent. Moreover, essentially the same conditions are predicted for all three bows except for a systematic reduction in speed and density with distance from the driving source. We find increased K-band extinctions in the bright regions as high as 2.9 magnitudes and suggest that the bow shocks become visible where the outflow impacts on dense clumps of cloud material. We propose that the outflow is carved out by episodes of pulsating jets. The jets, driven by central explosive events, are responsible for excavating a central tunnel through which radiation temporarily penetrates.Comment: 12 pages, 9 figure

    Characterization of GH2 and GH42 β-galactosidases derived from bifidobacterial infant isolates

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    Bifidobacteria are among the first and most abundant bacterial colonizers of the gastrointestinal tract of (breast-fed) healthy infants. Their success of colonising the infant gut is believed to be, at least partly, due to their ability to metabolize available carbon sources by means of secreted or intracellular glycosyl hydrolases (GHs). Among these, β-galactosidases are particularly relevant as they allow bifidobacteria to grow on β-galactosyl-linked saccharidic substrates, which are present in copious amounts in the milk-based diet of their infant host (e.g. lactose and human milk oligosaccharides). In the present study we employed an in silico analysis to identify GH family 2 and 42 β-galactosidases encoded by typical infant-associated bifidobacteria. Comparative genome analysis followed by characterisation of selected β-galactosidases revealed how these GH2 and GH42 members are distributed among these infant-associated bifidobacteria, while their hydrolytic activity towards growth substrates commonly available in the infant gut were also assessed

    Radiologic imaging in cystic fibrosis: cumulative effective dose and changing trends over 2 decades

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    Objective: With the increasing life expectancy for patients with cystic fibrosis (CF), and a known predisposition to certain cancers, cumulative radiation exposure from radiologic imaging is of increasing significance. This study explores the estimated cumulative effective radiation dose over a 17-year period from radiologic procedures and changing trends of imaging modalities over this period. Methods: Estimated cumulative effective dose (CED) from all thoracic and extrathoracic imaging modalities and interventional radiology procedures for both adult and pediatric patients with CF, exclusively attending a nationally designated CF center between 1992-2009 for > 1 year, was determined. The study period was divided into three equal tertiles, and estimated CED attributable to all radiologic procedures was estimated for each tertile. Results: Two hundred thirty patients met inclusion criteria (2,240 person-years of follow-up; 5,596 radiologic procedures). CED was > 75 mSv for one patient (0.43%), 36 patients (15.6%) had a CED between 20 and 75 mSv, 56 patients (24.3%) had a CED between 5 and 20 mSv, and in 138 patients (60%) the CED was estimated to be between 0 and 5 mSv over the study period. The mean annual CED per patient increased consecutively from 0.39 mSv/y to 0.47 mSv/y to 1.67 mSv/y over the tertiles one to three of the study period, respectively (P < .001). Thoracic imaging accounted for 46.9% of the total CED and abdominopelvic imaging accounted for 42.9% of the CED, respectively. There was an associated 5.9-fold increase in the use of all CT scanning per patient (P < .001). Conclusions: This study highlights the increasing exposure to ionizing radiation to patients with CF as a result of diagnostic imaging, primarily attributable to CT scanning. Increased awareness of CED and strategies to reduce this exposure are needed

    Bilateral mammoplasty for cancer: Surgical, oncological and patient-reported outcomes.

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    Introduction Bilateral mammoplasty (BM) can optimise oncological safety and aesthetic outcomes in women with large or ptotic breasts whose tumour to breast volume ratio or tumour location pose a challenge to standard breast-conserving therapy (BCT) and for whom mastectomy (with or without reconstruction) may be the only alternative.Methods We undertook a comprehensive analysis of surgical outcomes (complications according to the Clavien Dindo classification), acute radiation morbidity (Radiation Therapy Oncology Group classification), oncological outcomes, and patient satisfaction (BREAST-Q questionnaire) in women who underwent BM for breast cancer (BC) from June 2009-November 2014.Results 168 women were included. Median age was 55 years (range:33-84) and median tumour size at imaging 35 mm (range:0-170). Median specimen weight was 242 g (range 39-1824). The wise pattern technique was used in 87.5% of procedures. At least one complication occurred in 68 (40.5%) women, mostly Clavien Dindo grade 1. Grade 3 complications were infrequent (8.9%) but occurred mainly on the therapeutic mammoplasty (TM) side (p < 0.05). Complications were associated with higher BMI, specimen weight and longer time to radiotherapy (p < 0.05). Median follow-up was 37 months (range: 13-77). Local recurrence occurred in 3 (1.8%), distant metastases in 5 (3.0%), and 10 (6.0%) women have died. The median score for 'satisfaction with breasts' was 77 (range: 0-100).Conclusions This study provides concurrent data on surgical, oncological and patient-reported outcomes. It offers evidence that BM is an effective treatment for breast cancer in large- or ptotic-breasted women

    Standard wide local excision or bilateral reduction mammoplasty in large-breasted women with small tumours: Surgical and patient-reported outcomes.

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    Introduction Oncoplastic breast surgery is used to extend the role of breast-conserving surgery (BCS) to women with an unfavourable tumour to breast volume ratio. However, large-breasted women with a relatively small breast cancer may be offered bilateral reduction mammoplasty (BRM) despite being suitable for standard BCS as the more complex surgery may have advantages in terms of patient satisfaction and reduced adverse effects of radiotherapy.Patient and methods This retrospective study evaluated surgical and patient-reported outcome measures (PROMs) in large-breasted women with early ( 0.05).Conclusion Limitations of this study mean it can only be regarded as hypothesis-generating. Nonetheless, the trends merit a prospective study to investigate the optimal management of smaller breast cancers in larger-breasted women

    Validation of the Vectra XT three-dimensional imaging system for measuring breast volume and symmetry following oncological reconstruction.

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    PURPOSE:Three-dimensional surface imaging (3D-SI) of the breasts enables the measurement of breast volume and shape symmetry. If these measurements were sufficiently accurate and repeatable, they could be used in planning oncological breast surgery and as an objective measure of aesthetic outcome. The aim of this study was to validate the measurements of breast volume and symmetry provided by the Vectra XT imaging system. METHODS:To validate measurements, breast phantom models of true volume between 100 and 1000 cm3 were constructed and varying amounts removed to mimic breast tissue 'resections'. The volumes of the phantoms were measured using 3D-SI by two observers and compared to a gold standard. For intra-observer repeatability and inter-observer reproducibility in vivo, 16 patients who had undergone oncological breast surgery had breast volume and symmetry measured three times by two observers. RESULTS:A mean relative difference of 2.17 and 2.28% for observer 1 and 2 respectively was seen in the phantom measurements compared to the gold standard (n = 45, Bland Altman agreement). Intra-observer variation over ten repeated measurements demonstrated mean coefficients of variation (CV) of 0.58 and 0.49%, respectively. The inter-observer variation demonstrated a mean relative difference of 0.11% between the two observers. In patients, intra-observer variation over three repeated volume measurements for each observer was 3.9 and 3.8% (mean CV); the mean relative difference between observers was 5.78%. For three repeated shape symmetry measurements using RMS projection difference between the two breasts, the intra-observer variations were 8 and 14% (mean CV), the mean relative difference between observers was 0.43 mm for average symmetry values that ranged from about 3.5 to 15.5 mm. CONCLUSION:This first validation of breast volume and shape symmetry measurements using the Vectra XT 3D-SI system suggests that these measurements have the potential to assist in pre-operative planning and also as a measure of aesthetic outcome

    GALEX UV Color Relations for Nearby Early-Type Galaxies

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    We use GALEX/optical photometry to construct color-color relationships for early-type galaxies sorted by morphological type. We have matched objects in the GALEX GR1 public release and the first IR1.1 internal release, with the RC3 early-type galaxies having a morphological type -5.5<T<-1.5 with mean error in T<1.5, and mean error on (B-V)T<0.05. After visual inspection of each match, we are left with 130 galaxies with a reliable GALEX pipeline photometry in the far-UV and near-UV bands. This sample is divided into Ellipticals (-5.5<T<-3.5) and Lenticulars (-3.5<T<-1.5). After correction for the Galactic extinction, the color-color diagrams FUV-NUV vs. (B-V)_{Tc} are plotted for the two subsamples. We find a tight anti-correlation between the FUV-NUV and (B-V)_{Tc} colors for Ellipticals, the UV color getting bluer when the (B-V)_{Tc} get redder. This relationship very likely is an extension of the color-metallicity relationship into the GALEX NUV band. We suspect that the main source of the correlation is metal line blanketing in the NUV band. The FUV-NUV vs B-V correlation has larger scatter for lenticular galaxies; we speculate this reflects the presence of low level star formation. If the latter objects (i.e. those that are blue both in FUV-NUV and B-V) are interpreted as harboring recent star formation activity, this would be the case for a few percent (~4%) of Ellipticals and ~15% of Lenticulars; this would make about 10% of early-type galaxies with residual star formation in our full sample of 130 early-type galaxies. We also plot FUV-NUV vs. the Mg_2 index and central velocity dispersion. We find a tight anti-correlation between FUV-NUV and the Mg_2 index(...).Comment: 25 pages, 5 figures, accepted for publication in ApJS (abstract abridged), typos corrected in section 2.

    Consensus mutagenesis reveals that non-helical regions influence thermal stability of horseradish peroxidase

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    The enzyme horseradish peroxidase has many uses in biotechnology but a stabilized derivative would have even wider applicability. To enhance thermal stability, we applied consensus mutagenesis (used successfully with other proteins) to recombinant horseradish peroxidase and generated five single-site mutants. Unexpectedly, these mutations had greater effects on steady-state kinetics than on thermal stability. Only two mutants (T102A, T110V) marginally exceeded the wild type's thermal stability (4% and 10% gain in half-life at 50 °C respectively); the others (Q106R, Q107D, I180F) were less stable than wild type. Stability of a five-fold combination mutant matched that of Q106R, the least-stable single mutant. These results were perplexing: the Class III plant peroxidases display wide differences in thermal stability, yet the consensus mutations failed to reflect these natural variations. We examined the sequence content of Class III peroxidases to determine if there are identifiable molecular reasons for the stability differences observed. Bioinformatic analysis validated our choice of sites and mutations and generated an archetypal peroxidase sequence for comparison with extant sequences. It seems that both genetic variation and differences in protein stability are confined to non-helical regions due to the presence of a highly conserved alpha-helical structural scaffold in these enzymes
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