Spacecraft instrument calibration and stability

The following topics are covered: instrument degradation; the Solar Backscatter Ultraviolet (SBUV) Experiment; the Total Ozone Mapping Spectrometer (TOMS); the Stratospheric Aerosol and Gas Experiment 1 (SAGE-1) and SAGE-2 instruments; the Solar Mesosphere Explorer (SME) UV ozone and near infrared airglow instruments; and the Limb Infrared Monitor of the Stratosphere (LIMS)

Near-Infrared Polarimetric Adaptive Optics Observations of NGC 1068: A torus created by a hydromagnetic outflow wind

We present J' and K' imaging linear polarimetric adaptive optics observations of NGC 1068 using MMT-Pol on the 6.5-m MMT. These observations allow us to study the torus from a magnetohydrodynamical (MHD) framework. In a 0.5" (30 pc) aperture at K', we find that polarisation arising from the passage of radiation from the inner edge of the torus through magnetically aligned dust grains in the clumps is the dominant polarisation mechanism, with an intrinsic polarisation of 7.0%$\pm$2.2%. This result yields a torus magnetic field strength in the range of 4$-$82 mG through paramagnetic alignment, and 139$^{+11}_{-20}$ mG through the Chandrasekhar-Fermi method. The measured position angle (P.A.) of polarisation at K$'$ is found to be similar to the P.A. of the obscuring dusty component at few parsec scales using infrared interferometric techniques. We show that the constant component of the magnetic field is responsible for the alignment of the dust grains, and aligned with the torus axis onto the plane of the sky. Adopting this magnetic field configuration and the physical conditions of the clumps in the MHD outflow wind model, we estimate a mass outflow rate $\le$0.17 M$_{\odot}$ yr$^{-1}$ at 0.4 pc from the central engine for those clumps showing near-infrared dichroism. The models used were able to create the torus in a timescale of $\geq$10$^{5}$ yr with a rotational velocity of $\leq$1228 km s$^{-1}$ at 0.4 pc. We conclude that the evolution, morphology and kinematics of the torus in NGC 1068 can be explained within a MHD framework.Comment: 14 pages, 4 figures, Accepted by MNRA

A cost-effectiveness analysis of endoscopic eradication therapy for management of dysplasia arising in patients with Barrett's oesophagus in the United Kingdom

BACKGROUND AND AIMS: Endoscopic eradication therapy (EET) is the first line approach for treating Barrett's Esophagus (BE) related neoplasia globally. The British Society of Gastroenterology (BSG) recommend EET with combined endoscopic resection (ER) for visible dysplasia followed by endoscopic ablation in patients with both low and high grade dysplasia (LGD and HGD). The aim of this study is to perform a cost-effectiveness analysis for EET for treatment of all grades of dysplasia in BE patients. METHODS: A Markov cohort model with a lifetime time horizon was used to undertake a cost effectiveness analysis. A hypothetical cohort of United Kingdom (UK) patients diagnosed with BE entered the model. Patients in the treatment arm with LGD and HGD received EET and patients with non-dysplastic BE (NDBE) received endoscopic surveillance only. In the comparator arm, patients with LGD, HGD and NDBE received endoscopic surveillance only. A UK National Health Service (NHS) perspective was adopted and the incremental cost effectiveness ratio (ICER) was calculated. Sensitivity analysis was conducted on key input parameters. RESULTS: EET for patients with LGD and HGD arising in BE is cost-effective compared to endoscopic surveillance alone (lifetime ICER £3,006 per QALY gained). The results show that as the time horizon increases, the treatment becomes more cost-effective. The five year financial impact to the UK NHS of introducing EET is £7.1m. CONCLUSIONS: EET for patients with low and high grade BE dysplasia, following updated guidelines from the BSG has been shown to be cost-effective for patients with BE in the UK

The cost-effectiveness of radiofrequency ablation for treating patients with gastric antral vascular ectasia refractory to first line endoscopic therapy

OBJECTIVE: This economic evaluation aims to provide a preliminary assessment of the cost-effectiveness of radiofrequency ablation (RFA) compared with argon plasma coagulation (APC), when used to treat APC-refractory gastric antral vascular ectasia (GAVE) in symptomatic patients.METHODS: A Markov model was constructed to undertake a cost-utility analysis for adults with persistent symptoms secondary to GAVE refractory to first line endoscopic therapy. The economic evaluation was conducted from a UK NHS and personal social services (PSS) perspective, with a 20-year time horizon, comparing RFA with APC. Patients transfer between health states defined by haemoglobin level. The clinical effectiveness data were sourced from expert opinion, resource use and costs were reflective of the UK NHS and benefits were quantified using Quality Adjusted Life Years (QALYs) with utility weights taken from the literature. The primary output was the Incremental Cost-Effectiveness Ratio (ICER), expressed as cost per QALY gained.RESULTS: Over a lifetime time horizon, the base case ICER was £4,840 per QALY gained with an 82.2% chance that RFA was cost-effective at a threshold of £20,000 per QALY gained. The model estimated that implementing RFA would result in reductions in the need for intravenous iron, endoscopic intervention and requirement for blood transfusions by 27.1%, 32.3% and 36.5% respectively. Compared to APC, RFA was associated with an estimated 36.7% fewer procedures.CONCLUSIONS: RFA treatment is likely to be cost-effective for patients with ongoing symptoms following failure of first line therapy with APC and could lead to substantive reductions in health care resource

Domestic ventilation rates, indoor humidity and dust mite allergens : are our homes causing the asthma pandemic?

This paper is concerned with historical changes in domestic ventilation rates, relative humidity and the associated risk of house dust mite colonization. A controlled trial evaluated allergen and water vapour control measures on the level of house dust mite (HDM) Der p1 allergen and indoor humidity, concurrently with changes in lung function in 54 subjects who completed the protocol. Mechanical heat recovery ventilation units significantly reduced moisture content in the active group, while HDM allergen reservoirs in carpets and beds were reduced by circa 96%. Self reported health status confirmed a significant clinical improvement in the active group. The study can form the basis for assessing minimum winter ventilation rates that can suppress RH below the critical ambient equilibrium humidity of 60% and thus inhibit dust mite colonization and activity in temperate and maritime in' uenced climatic regions