The prevalence of dust on the exoplanet HD 189733b from Hubble and Spitzer observations

The hot Jupiter HD189733b is the most extensively observed exoplanet. Its atmosphere has been detected and characterised in transmission and eclipse spectroscopy, and its phase curve measured at several wavelengths. This paper brings together results of our campaign to obtain the complete transmission spectrum of the atmosphere of this planet from UV to IR with HST, using STIS, ACS and WFC3. We provide a new tabulation of the transmission spectrum across the entire visible and IR range. The radius ratio in each wavelength band was rederived to ensure a consistent treatment of the bulk transit parameters and stellar limb-darkening. Special care was taken to correct for, and derive realistic estimates of the uncertainties due to, both occulted and unocculted star spots. The combined spectrum is very different from the predictions of cloud-free models: it is dominated by Rayleigh scattering over the whole visible and near infrared range, the only detected features being narrow Na and K lines. We interpret this as the signature of a haze of condensate grains extending over at least 5 scale heights. We show that a dust-dominated atmosphere could also explain several puzzling features of the emission spectrum and phase curves, including the large amplitude of the phase curve at 3.6um, the small hot-spot longitude shift and the hot mid-infrared emission spectrum. We discuss possible compositions and derive some first-order estimates for the properties of the putative condensate haze/clouds. We finish by speculating that the dichotomy between the two observationally defined classes of hot Jupiter atmospheres, of which HD189733b and HD209458b are the prototypes, might not be whether they possess a temperature inversion, but whether they are clear or dusty. We also consider the possibility of a continuum of cloud properties between hot Jupiters, young Jupiters and L-type brown dwarfs.Comment: Accepted for publication in MNRAS. 31 pages, 19 figures, 8 table

The migration of single hot Jupiters: Balance of evidence tips towards dynamical and tidal evolution

In this thesis, we revisit the seventeen year old question of how hot Jupiters got to their short period orbits, given that gas-giant planet building is supposed to take place beyond the ice-line at about 3 AU. Two major theories are generally used to explain this mystery. Firstly, exchange of energy and angular momentum between the newly-built planet and the progenitor dust and gas disk could result in planetary migration to a short period. This is generally believed to result in planets on circular orbits, with orbital angular momenta that are aligned with the host star spin. The competing theory which has gained more support in recent years, is that gravitational interactions leading to planet-planet scattering and/or Kozai interactions with massive and distant objects caused the planets to migrate violently (scattering) or slowly (Kozai) to short period, eccentric and misaligned orbits. These orbits are then expected to circularise and align under tidal interactions with the host star. In addition, the host star is expected to show evidence of spin-up if the tide on the star is strong enough. Our contribution to this field is to provide additional support for the scenario involving dynamical interaction and tidal damping. We present observational evidence in the form of 158 new radial velocity measurements for 12 planets and a reanalysis of existing radial velocity data and photometric constraints from the literature for a total of 64 planetary systems. We also critically consider a further 30 newly announced planets from the literature. We show that there is no evidence for a finite eccentricity in several cases that were previously claimed to be “exceptions” to the observed trend that close-in planets are on circular orbits and the generally accepted reason that they underwent strong tidal interactions. We also show that the dissipative effect of tides raised in the planet by the star and vice versa explain all the eccentricity and spin-orbit alignment measurements available for transiting planets. We find evidence for excess rotation of the star in 6 systems, showing that heavy and close-in objects can exert strong tidal effects on the star. Hot Jupiters on circular orbits clump on the mass-period relation, which thus appears to be related to the stopping mechanism of orbital migration for hot Jupiters

Duodenal biopsies for the diagnosis of coeliac disease: are we adhering to current guidance?

Background: The British Society of Gastroenterology guidelines recommend taking at least four duodenal biopsy specimens at the time of upper gastrointestinal (UGI) endoscopy if coeliac disease (CD) is suspected and it has been shown to increase the diagnostic yield of CD. We assessed the compliance to these guidelines within our institution. We then applied measures to improve our compliance rate and assessed the resulting impact on our diagnostic rate of CD. Methods: We performed a retrospective audit of electronic records for all patients, with no prior diagnosis of CD, who underwent UGI endoscopy with duodenal biopsies between August 2014 and May 2015. We implemented measures to raise awareness among endoscopy users at our institution and carried out a reaudit between February and May 2016. Results: 924 patients were found to be eligible in the first part of the study and 278 in the second part. The proportion of patients who had ≥4 biopsy specimens submitted increased from 21.9% to 60.8% (p<0.001). The diagnostic rate of CD increased from 3.5% in the audit group to 7.6% in the reaudit group (p=0.004). A positive serology result and suspected CD as an indication for biopsy were found to be independent predictors of the likelihood of complying with guidelines. Conclusions: Our study suggests that taking <4 duodenal biopsy specimens to assess for the presence of CD may lead to the diagnosis of CD being missed. Simple measures can improve the local compliance rate to current guidelines

The prevalence of dust on the exoplanet HD 189733b from Hubble and Spitzer observations

This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.The hot Jupiter HD 189733b is the most extensively observed exoplanet. Its atmosphere has been detected and characterized in transmission and eclipse spectroscopy, and its phase curve measured at several wavelengths. This paper brings together the results of our campaign to obtain the complete transmission spectrum of the atmosphere of this planet from UV to infrared with the Hubble Space Telescope, using the STIS, ACS and WFC3 instruments. We provide a new tabulation of the transmission spectrum across the entire visible and infrared range. The radius ratio in each wavelength band was re-derived, where necessary, to ensure a consistent treatment of the bulk transit parameters and stellar limb darkening. Special care was taken to correct for, and derive realistic estimates of the uncertainties due to, both occulted and unocculted star spots. The combined spectrum is very different from the predictions of cloud-free models for hot Jupiters: it is dominated by Rayleigh scattering over the whole visible and near-infrared range, the only detected features being narrow sodium and potassium lines. We interpret this as the signature of a haze of condensate grains extending over at least five scaleheights. We show that a dust-dominated atmosphere could also explain several puzzling features of the emission spectrum and phase curves, including the large amplitude of the phase curve at 3.6 μm, the small hotspot longitude shift and the hot mid-infrared emission spectrum. We discuss possible compositions and derive some first-order estimates for the properties of the putative condensate haze/clouds. We finish by speculating that the dichotomy between the two observationally defined classes of hot Jupiter atmospheres, of which HD 189733b and HD 209458b are the prototypes, might not be whether they possess a temperature inversion, but whether they are clear or dusty. We also consider the possibility of a continuum of cloud properties between hot Jupiters, young Jupiters and L-type brown dwarfs.Science and Technology Facilities Council (STFC)NASANSFTennessee State UniversityState of Tennesse

Probing the haze in the atmosphere of HD 189733b with HST/WFC3 transmission spectroscopy

We present Hubble Space Telescope near-infrared transmission spectroscopy of the transiting exoplanet HD 189733b, using Wide Field Camera 3. This consists of time-series spectra of two transits, used to measure the wavelength dependence of the planetary radius. These observations aim to test whether the Rayleigh scattering haze detected at optical wavelengths extends into the near-infrared, or if it becomes transparent leaving molecular features to dominate the transmission spectrum. Due to saturation and non-linearity affecting the brightest (central) pixels of the spectrum, light curves were extracted from the blue and red ends of the spectra only, corresponding to wavelength ranges of 1.099-1.168 um and 1.521-1.693 um, respectively, for the first visit, and 1.082-1.128 um and 1.514-1.671 um for the second. The light curves were fitted using a Gaussian process model to account for instrumental systematics whilst simultaneously fitting for the transit parameters. This gives values of the planet-to-star radius ratio for the blue and red light curves of 0.15650\pm0.00048 and 0.15634\pm0.00032, respectively, for visit one and 0.15716\pm0.00078 and 0.15630\pm0.00037 for visit 2 (using a quadratic limb darkening law). The planet-to-star radius ratios measured in both visits are consistent, and we see no evidence for the drop in absorption expected if the haze that is observed in the optical becomes transparent in the infrared. This tentatively suggests that the haze dominates the transmission spectrum of HD 189733b into near-infrared wavelengths, although more robust observations are required to provide conclusive evidence.Comment: 9 pages, 6 figures, 1 table, Accepted for publication in MNRA

Improvements in forecasting intense rainfall: results from the FRANC (forecasting rainfall exploiting new data assimilation techniques and novel observations of convection) project

The FRANC project (Forecasting Rainfall exploiting new data Assimilation techniques and Novel observations of Convection) has researched improvements in numerical weather prediction of convective rainfall via the reduction of initial condition uncertainty. This article provides an overview of the project’s achievements. We highlight new radar techniques: correcting for attenuation of the radar return; correction for beams that are over 90% blocked by trees or towers close to the radar; and direct assimilation of radar reflectivity and refractivity. We discuss the treatment of uncertainty in data assimilation: new methods for estimation of observation uncertainties with novel applications to Doppler radar winds, Atmospheric Motion Vectors, and satellite radiances; a new algorithm for implementation of spatially-correlated observation error statistics in operational data assimilation; and innovative treatment of moist processes in the background error covariance model. We present results indicating a link between the spatial predictability of convection and convective regimes, with potential to allow improved forecast interpretation. The research was carried out as a partnership between University researchers and the Met Office (UK). We discuss the benefits of this approach and the impact of our research, which has helped to improve operational forecasts for convective rainfall event

The classification of Information and Communication Technology Investment in Financial Accounting

Financial accounting is well known in its responsibility for book keeping the organisational expenditure and the preparation of the financial statements. ICT investment has become important to investors and not reporting these investments on financial statement leads to misevaluation of the organisation market value. Moreover, the misclassification of ICT investment has been indicated, yet not investigated in the past researches. The unreported ICT investment and the misclassification of ICT investment could affect the measurement of ICT investment at firm level. By analysing the content of the financial statement for 86 firms listing in Australian Stock Exchange, this study explains how ICT investments were being classified with the other investment in financial reports from 2006 to 2010. Differentiating between ICT asset and expense is an initial step into the understanding about the classification of ICT investment in financial accounting. The accounting standards requires the capitalisation conditions including future economic benefit, controllability, identifiability, existence, and reliability measurement to be justified for the expenditure before it can be capitalised as asset. The study use fuzzy set qualitative and comparative analysis (fsQCA) to analyse the information collected from the experts in the accounting fields. Base on fsQCA analysis, the study is able to shows that the factors considered by the organisation to differentiate ICT asset from ICT expense is beyond the requirement in definition of asset stated in the International Accounting Standards and the Australian Accounting Standards

Surgical site infections after emergency hernia repair: substudy from the Management of Acutely Symptomatic Hernia (MASH) study

Introduction Acutely symptomatic abdominal wall and groin hernias (ASH) are a common acute surgical presentation. There are limited data to guide decisions related to surgical repair technique and use of antibiotics, which can be driven by increased risk of surgical site infection (SSI) in this group. This study aims to report rates of SSI following ASH repair and explore the use of patient-reported outcome measure reporting in this setting. Methods An 18-week, UK-based, multicentre prospective cohort study (NCT04197271) recruited adults with ASH. This study reports operatively managed patients. Data on patient characteristics, inpatient management, quality of life, complications, and wound healing (Bluebelle score) were collected. Descriptive analyses were performed to estimate event rates of SSI and regression analysis explored the relationship between Bluebelle scores and SSI. The 30 and 90-day follow-up visits assessed complications and quality of life. Results The MASH study recruited 273 patients, of whom 218 were eligible for this study, 87.2 per cent who underwent open repair. Mesh was used in 123 patients (50.8 per cent). Pre- and postoperative antibiotics were given in 163 (67.4 per cent) and 28 (11.5 per cent) patients respectively. There were 26 reported SSIs (11.9 per cent). Increased BMI, incisional, femoral, and umbilical hernia were associated with higher rates of SSI (P = 0.006). In 238 patients, there was a difference in healthy utility values at 90 days between patients with and without SSI (P = 0.025). Also, when analysing 191 patients with Bluebelle scores, those who developed an SSI had higher Bluebelle values (P < 0.001). Conclusion SSI is frequent in repair of acutely symptomatic hernia and correlates with BMI and site of hernia

Incorporation of evidence-based surgery into the curriculum

Surgeons have historically learned their craft through the apprenticeship model from their mentors. Knowledge and practices acquired this way can rapidly become outdated. Providing high-quality care to patients requires surgeons to keep their knowledge up to date in line with evolving new evidence. The principles of evidence-based medicine (EBM) and its application to surgery, evidence-based surgery (EBS), are pivotal in updating and refining surgical practice. Changing from the conventional practice of surgical education to a structured evidence-based format requires a transformative process in all the levels of surgical practice encompassing trainees and trainers. Equally important is providing an optimal environment to review the evidence and deliver the surgical teaching and incorporate effective assessment tools to monitor the process. In this article, we revisit the levels of evidence and explore the different issues related to EBS such as barriers to EBS, incorporation of EBS to the surgical curriculum and discuss practical ways to implement EBS in the surgical curriculum