308 research outputs found
A Time Series of BV photometry and Halpha Emission Fluxes of the Eclipsing Binary VV Cep
VV Cephei (= HR 8383 = HD 208816) is the brightest eclipsing M supergiant binary (M2 Iab + B0-2? V) in the sky, and is a massive binary with one of the
longest known orbital periods (7430 days = 20.34 years) of any eclipsing system. With the next eclipse beginning in August 2017, and lasting nearly
two years (650 days) from 1st to 4th contact, an extensive observational campaign is planned. This paper focusses on the photometric variability
of the system out of eclipse, and presents and photometry and H emission fluxes observed over the period from mid-2008 through
late 2016. The and light curves show correlated variability with peak power of 145 days, presumably due to low-amplitude pulsations of
the M supergiant. The H emission fluxes show a short-term variability, but the sampling is not sufficient to permit quantitative analysis.
However, the H fluxes also appear to show a long-term modulation related to the variable orbital separation of this eccentric binary
Periodic Halpha Emission in the Eclipsing Binary VV Cephei
We present a high-cadence time series of spectroscopic observations of the H emission line profile obtained during the egress and total eclipse phases of the M supergiant binary VV Cephei (M2 Iab + B0-2 V) for the 2017-2018 eclipse. Medium-resolution spectroscopy, obtained at an almost nightly cadence by the ARAS Spectroscopy Group from April 2017 through June 2018, has been used to construct a time-series of equivalent widths (EWs) of the H emission line flux. The peak fluxes of the blue (V) component and the red (R) component relative to the continuum, as well as their ratio, V/R, have also been found. We report on a new 43.5-day periodic variation in the H emission that is present throughout the entire time series and, in particular, persists through mid-eclipse
Blur Reduction in Ultrasonic Images Using Pseudo Three-Dimensional Wiener Filtering
The ability to quantitatively image material anomalies with ultrasonic methods is severely restricted by the axial and lateral resolution of the interrogating transducer. Axial resolution is controlled by the pulse duration of the transducer with shorter pulse durations yielding better axial resolution. Lateral resolution is controlled by the width of the interrogating beam with narrower beams providing better lateral resolutio
Two Dimensional Pseudo-Wiener Filtering in Ultrasonic Imaging for Nondestructive Evaluation Applications
This paper deals with the use of a two dimensional pseudo-Wiener filter for ultrasonic image enhancement. Experimental results are presented to demonstrate the effectiveness of the technique for the improvement of the lateral resolution and image enhancement of ultrasonic images in materials such as graphite/epoxy composites and stainless steel. The difficulties encountered in the implementation of the filter will be delineated. Methods of overcoming some of these ‘implementational hurdles’ will be suggested
Spectroscopic variability of two Oe stars
The Oe stars HD45314 and HD60848 have recently been found to exhibit very
different X-ray properties: whilst HD60848 has an X-ray spectrum and emission
level typical of most OB stars, HD45314 features a much harder and brighter
X-ray emission, making it a so-called gamma Cas analogue. Monitoring the
optical spectra could provide hints towards the origin of these very different
behaviours. We analyse a large set of spectroscopic observations of HD45314 and
HD60848, extending over 20 years. We further attempt to fit the H-alpha line
profiles of both stars with a simple model of emission line formation in a
Keplerian disk. Strong variations in the strengths of the H-alpha, H-beta, and
He I 5876 emission lines are observed for both stars. In the case of HD60848,
we find a time lag between the variations in the equivalent widths of these
lines. The emission lines are double peaked with nearly identical strengths of
the violet and red peaks. The H-alpha profile of this star can be successfully
reproduced by our model of a disk seen under an inclination of 30 degrees. In
the case of HD45314, the emission lines are highly asymmetric and display
strong line profile variations. We find a major change in behaviour between the
2002 outburst and the one observed in 2013. This concerns both the relationship
between the equivalent widths of the various lines and their morphologies at
maximum strength (double-peaked in 2002 versus single-peaked in 2013). Our
simple disk model fails to reproduce the observed H-alpha line profiles of
HD45314. Our results further support the interpretation that Oe stars do have
decretion disks similar to those of Be stars. Whilst the emission lines of
HD60848 are explained by a disk with a Keplerian velocity field, the disk of
HD45314 seems to have a significantly more complex velocity field that could be
related to the phenomenon that produces its peculiar X-ray emission.Comment: Accepted for Publication in A&
Illness perceptions and quality of life in patients with non-small-cell lung cancer
__Purpose:__ Examine illness perceptions, functional health and quality of life of lung cancer patients throughout chemotherapy treatment.
__Patients and Methods:__ Longitudinal design with baseline measure 12 days after the first chemotherapy and follow-up measure 3 months later, where illness perceptions (BIPQ), functional health, and quality of life (EORTC QLQ-C-30) were measured. A total of 21 patients with non-small-cell lung cancer took part. Non-parametric testing was performed given the pilot nature of the study and the associated relatively small sample size.
__Results:__ Small to medium changes in illness perceptions and functional health between the two measurement points were detected, with both becoming more positive. More negative illness perceptions at the beginning of the treatment were associated with less functioning and lower quality of life at both beginning and end of treatment.
__Conclusion:__ Addressing illness perceptions seems a clinically relevant approach in improving functioning and quality of life of patients with non-small-cell lung cancer
Association between duration of symptoms and severity of disease at first presentation to paediatric rheumatology: results from the Childhood Arthritis Prospective Study
Objectives. To study the association between disease severity at first presentation to paediatric rheumatology (PRh) and length of time since symptom onset in children recruited to the Childhood Arthritis Prospective Study
Effects of switching between anti-TNF therapies on HAQ response in patients who do not respond to their first anti-TNF drug
Objectives. Small studies have shown an improvement in disease activity in patients with RA who have switched between anti-TNF therapies for reasons of inefficacy. However, it is not clear whether switching improves longer term outcomes, such as disability. This analysis compares changes in HAQ scores 1 yr following lack of response to a first anti-TNF based on subsequent treatment during that year
Massive stars in the giant molecular cloud G23.3−0.3 and W41
Context. Young massive stars and stellar clusters continuously form in the Galactic disk, generating new Hii regions within their natal giant molecular clouds and subsequently enriching the interstellar medium via their winds and supernovae.Aims. Massive stars are among the brightest infrared stars in such regions; their identification permits the characterisation of the star formation history of the associated cloud as well as constraining the location of stellar aggregates and hence their occurrence as a function of global environment.Methods. We present a stellar spectroscopic survey in the direction of the giant molecular cloud G23.3−0.3. This complex is located at a distance of ~4–5 kpc, and consists of several Hii regions and supernova remnants.Results. We discovered 11 OfK+ stars, one candidate luminous blue variable, several OB stars, and candidate red supergiants. Stars with K-band extinction from ~1.3–1.9 mag appear to be associated with the GMC G23.3−0.3; O and B-types satisfying this criterion have spectrophotometric distances consistent with that of the giant molecular cloud. Combining near-IR spectroscopic and photometric data allowed us to characterize the multiple sites of star formation within it. The O-type stars have masses from ~25–45 M⊙, and ages of 5–8 Myr. Two new red supergiants were detected with interstellar extinction typical of the cloud; along with the two RSGs within the cluster GLIMPSE9, they trace an older burst with an age of 20–30 Myr. Massive stars were also detected in the core of three supernova remnants – W41, G22.7−0.2, and G22.7583−0.4917.Conclusions. A large population of massive stars appears associated with the GMC G23.3−0.3, with the properties inferred for them indicative of an extended history of stars formation
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