566 research outputs found
Recent Transits of the Super-Earth Exoplanet GJ 1214b
We report recent ground-based photometry of the transiting super-Earth
exoplanet GJ1214b at several wavelengths, including the infrared near 1.25
microns (J-band). We observed a J-band transit with the FLAMINGOS infrared
imager and the 2.1-meter telescope on Kitt Peak, and we observed several
optical transits using a 0.5-meter telescope on Kitt Peak and the 0.36-meter
Universidad de Monterrey Observatory telescope. Our high-precision J-band
observations exploit the brightness of the M-dwarf host star at this infrared
wavelength as compared to the optical, as well as being significantly less
affected by stellar activity and limb darkening. We fit the J-band transit to
obtain an independent determination of the planetary and stellar radii. Our
radius for the planet (2.61^+0.30_-0.11 Earth radii) is in excellent agreement
with the discovery value reported by Charbonneau et al. based on optical data.
We demonstrate that the planetary radius is insensitive to degeneracies in the
fitting process. We use all of our observations to improve the transit
ephemeris, finding P=1.5804043 +/- 0.0000005 days, and T0=2454964.94390 +/-
0.00006 BJD.Comment: Accepted for ApJ Letters, 7 pages, 3 Figures, 2 Table
âBlock teachingâ â exploring lecturers' perceptions of intensive modes of delivery in the context of undergraduate education
This article evaluates changes in teaching delivery during the first year of an undergraduate Tourism Management degree programme at a university in the North West of England. Moving from traditional semesterised mode, delivery was changed to shortened, time-intensive modules delivered one at a time, for two full days (six hours per day) over a three-week period. This was implemented in response to student feedback and concerns regarding student outcomes. Albeit limited, previous research suggests that intensive forms of delivery can improve engagement, attendance and attainment, particularly amongst students from diverse entry pathways. Although it is clear that the efficacy of block teaching relies heavily on â and creates new pressures for â teaching staff, little research has explored those impacts. Here instead, the perceptions of teaching staff were the focus. A qualitative approach was taken using an anonymous, online questionnaire, completed following one full year of block teaching. Findings suggest that, although most lecturers found that block teaching enabled them to manage their time more effectively, as the year progressed, block teaching negatively affected student attendance and subsequently hampered deep learning. Fully-integrated placement of assessment and use of one intensive module to aid transition was recommended to help overcome these issues
Readiness of Quantum Optimization Machines for Industrial Applications
There have been multiple attempts to demonstrate that quantum annealing and,
in particular, quantum annealing on quantum annealing machines, has the
potential to outperform current classical optimization algorithms implemented
on CMOS technologies. The benchmarking of these devices has been controversial.
Initially, random spin-glass problems were used, however, these were quickly
shown to be not well suited to detect any quantum speedup. Subsequently,
benchmarking shifted to carefully crafted synthetic problems designed to
highlight the quantum nature of the hardware while (often) ensuring that
classical optimization techniques do not perform well on them. Even worse, to
date a true sign of improved scaling with the number of problem variables
remains elusive when compared to classical optimization techniques. Here, we
analyze the readiness of quantum annealing machines for real-world application
problems. These are typically not random and have an underlying structure that
is hard to capture in synthetic benchmarks, thus posing unexpected challenges
for optimization techniques, both classical and quantum alike. We present a
comprehensive computational scaling analysis of fault diagnosis in digital
circuits, considering architectures beyond D-wave quantum annealers. We find
that the instances generated from real data in multiplier circuits are harder
than other representative random spin-glass benchmarks with a comparable number
of variables. Although our results show that transverse-field quantum annealing
is outperformed by state-of-the-art classical optimization algorithms, these
benchmark instances are hard and small in the size of the input, therefore
representing the first industrial application ideally suited for testing
near-term quantum annealers and other quantum algorithmic strategies for
optimization problems.Comment: 22 pages, 12 figures. Content updated according to Phys. Rev. Applied
versio
Personal tutoring: a recognition of âlevelnessâ in the support for undergraduates
The changing terrain of higher education in the UK, and particularly the greater diversity of the student body, has undoubtedly led to the need for universities to provide greater support, both from frontline teaching staff and in the provision of extra institutional services. Added to the mix are sectoral concerns for the wellbeing and welfare of the student. It is therefore unsurprising that we are seeing a renewed focus on, and interest in, personal tutoring. Taking a qualitative approach, we set out to explore the needs of undergraduate students, on an event management programme, in relation to personal tutoring. Outlined in this paper are the different senses of personal tutoring as student transition through their course
Applying machine learning to improve simulations of a chaotic dynamical system using empirical error correction
Dynamical weather and climate prediction models underpin many studies of the
Earth system and hold the promise of being able to make robust projections of
future climate change based on physical laws. However, simulations from these
models still show many differences compared with observations. Machine learning
has been applied to solve certain prediction problems with great success, and
recently it's been proposed that this could replace the role of
physically-derived dynamical weather and climate models to give better quality
simulations. Here, instead, a framework using machine learning together with
physically-derived models is tested, in which it is learnt how to correct the
errors of the latter from timestep to timestep. This maintains the physical
understanding built into the models, whilst allowing performance improvements,
and also requires much simpler algorithms and less training data. This is
tested in the context of simulating the chaotic Lorenz '96 system, and it is
shown that the approach yields models that are stable and that give both
improved skill in initialised predictions and better long-term climate
statistics. Improvements in long-term statistics are smaller than for single
time-step tendencies, however, indicating that it would be valuable to develop
methods that target improvements on longer time scales. Future strategies for
the development of this approach and possible applications to making progress
on important scientific problems are discussed.Comment: 26p, 7 figures To be published in Journal of Advances in Modeling
Earth System
The systemic inflammatory response, weight loss, performance status and survival in patients with inoperable non-small cell lung cancer
The relationship between the magnitude of systemic inflammatory response and the nutritional/functional parameters in patients with inoperable non-small cell lung cancer were studied. The extent of weight loss, albumin, C-reactive protein, performance status and quality of life was measured in 106 patients with inoperable non-small cell lung cancer (stages III and IV). Survival analysis was performed using the Cox proportional hazard model. The majority of patients were male and almost 80% had elevated circulating C-reactive protein concentrations (>10âmgâlâ1). On multivariate analysis, age (P=0.012), tumour type (0.002), weight loss (P=0.056), C-reactive protein (P=0.047), Karnofsky performance status (P=0.002) and fatigue (P=0.046) were independent predictors of survival. The patients were grouped according to the magnitude of the C-reactive protein concentrations (â©œ10, 11â100 and >100âmgâlâ1). An increase in the magnitude of the systemic inflammatory response was associated with increased weight loss (P=0.004), reduced albumin concentrations (P=0.001), reduced performance status (P=0.060), increased fatigue (P=0.011) and reduced survival (HR 1.936 95%CI 1.414â2.650, P<0.001). These results indicate that the majority of patients with inoperable non-small cell lung cancer have evidence of a systemic inflammatory response. Furthermore, an increase in the magnitude of the systemic inflammatory response resulted in greater weight loss, poorer performance status, more fatigue and poorer survival
ALMA sub-mm maser and dust distribution of VY Canis Majoris
Cool, evolved stars have copious, enriched winds. The structure of these
winds and the way they are accelerated is not well known. We need to improve
our understanding by studying the dynamics from the pulsating stellar surface
to about 10 stellar radii, where radiation pressure on dust is fully effective.
Some red supergiants have highly asymmetric nebulae, implicating additional
forces. We retrieved ALMA Science Verification data providing images of sub-mm
line and continuum emission from VY CMa. This enables us to locate water masers
with milli-arcsec precision and resolve the dusty continuum. The 658-, 321- and
325-GHz masers lie in irregular, thick shells at increasing distances from the
centre of expansion. For the first time this is confirmed as the stellar
position, coinciding with a compact peak offset to the NW of the brightest
continuum emission. The maser shells (and dust formation zone) overlap but
avoid each other on tens-au scales. Their distribution is broadly consistent
with excitation models but the conditions and kinematics appear to be
complicated by wind collisions, clumping and asymmetries.Comment: Letter 4 pages, 5 figures plus appendix with 3 figures. Accepted by
Astronomy and Astrophysics Letter
Foreign body ingestion mimicking irritable bowel syndrome: a case report
<p>Abstract</p> <p>Introduction</p> <p>Foreign body ingestion is associated with a variety of symptoms and complications, often mimicking various diseases. This case report describes an unusual presentation following foreign body ingestion.</p> <p>Case presentation</p> <p>A 56-year-old Greek Caucasian woman presented to a primary care setting, in rural Crete, Greece, with complaints of abdominal pain, cramping and bloating, for the last four months. Alternating constipation and diarrhea was reported. The patient had unknowingly ingested a foreign body that resulted in an irritable bowel syndrome-like presentation.</p> <p>Conclusions</p> <p>This case report emphasizes the need for a high index of suspicion from physicians for a wide differential in their approach to abdominal complaints, as well as the importance of an individualized approach to patients in the setting of clinical medicine.</p
Reasons for accepting or declining participation in the ASPRE trial : a qualitative study with women at highârisk of preterm preâeclampsia
Aerodynamic investigations of ventilated brake discs.
The heat dissipation and performance of a ventilated brake disc strongly depends
on the aerodynamic characteristics of the flow through the rotor passages. The
aim of this investigation was to provide an improved understanding of ventilated
brake rotor flow phenomena, with a view to improving heat dissipation, as well
as providing a measurement data set for validation of computational fluid
dynamics methods. The flow fields at the exit of four different brake rotor
geometries, rotated in free air, were measured using a five-hole pressure probe
and a hot-wire anemometry system. The principal measurements were taken using
two-component hot-wire techniques and were used to determine mean and unsteady
flow characteristics at the exit of the brake rotors. Using phase-locked data
processing, it was possible to reveal the spatial and temporal flow variation
within individual rotor passages. The effects of disc geometry and rotational
speed on the mean flow, passage turbulence intensity, and mass flow were
determined. The rotor exit jet and wake flow were clearly observed as
characterized by the passage geometry as well as definite regions of high and
low turbulence. The aerodynamic flow characteristics were found to be reasonably
independent of rotational speed but highly dependent upon rotor geometry
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