Markov-Switching GARCH Modelling of Value-at-RisK

This paper proposes an asymmetric Markov regime-switching (MS) GARCH model to estimate value-at-risk (VaR) for both long and short positions. This model improves on existing VaR methods by taking into account both regime change and skewness or leverage effects. The performance of our MS model and single-regime models is compared through an innovative backtesting procedure using daily data for UK and US market stock indices. The findings from exceptions and regulatory-based tests indicate the MS-GARCH specifications clearly outperform other models in estimating the VaR for both long and short FTSE positions and also do quite well for S&P positions. We conclude that ignoring skewness and regime changes has the effect of imposing larger than necessary conservative capital requirements

State estimation and absolute image registration for geosynchronous satellites

Spacecraft state estimation and the absolute registration of Earth images acquired by cameras onboard geosynchronous satellites are described. The basic data type of the procedure consists of line and element numbers of image points called landmarks whose geodetic coordinates, relative to United States Geodetic Survey topographic maps, are known. A conventional least squares process is used to estimate navigational parameters and camera pointing biases from observed minus computed landmark line and element numbers. These estimated parameters along with orbit and attitude dynamic models are used to register images, using an automated grey level correlation technique, inside the span represented by the landmark data. In addition, the dynamic models can be employed to register images outside of the data span in a near real time mode. An important application of this mode is in support of meteorological studies where rapid data reduction is required for the rapid tracking and predicting of dynamic phenomena

Orbit/attitude estimation for the GOES spacecraft using VAS landmark data

A software system is described which provides for batch least squares estimation of spacecraft orbit, attitude, and camera bias parameters using image data from the Geostationary Operational Environmental Satellites (GOES). The image data are obtained by the Visible and Infrared Spin Scan Radiometer (VISSR) Atmospheric Sounder (VAS). The resulting estimated parameters are used for absolute image registration. Operating in the Digital Equipment Corporation (DEC) PDP-11/70 computer, the FORTRAN system also includes the capabilities of image display and manipulations. An overview of the system is presented as well as some numerical results obtained from observations taken by the SMS-2 satellite over a 3 day interval in August 1975

Systemic therapy for vulval Erosive Lichen Planus (the 'hELP' trial): study protocol for a randomised controlled trial

BACKGROUND: Erosive lichen planus affecting the vulva (ELPV) is a relatively rare, chronic condition causing painful raw areas in the vulvovaginal region. Symptoms are pain and burning, which impact upon daily living. There is paucity of evidence regarding therapy. A 2012 Cochrane systematic review found no randomised controlled trials (RCTs) in this field. Topically administered corticosteroids are the accepted first-line therapy: however, there is uncertainty as to which second-line treatments to use. Several systemic agents have been clinically noted to show promise for ELPV refractory to topically administered corticosteroids but there is no RCT evidence to support these. The 'hELP' study is a RCT with an internal pilot phase designed to provide high-quality evidence. METHODS/DESIGN: The objective is to test whether systemic therapy in addition to standard topical therapy is a beneficial second-line treatment for ELPV. Adjunctive systemic therapies used are hydroxychloroquine, methotrexate, mycophenolate mofetil and prednisolone. Topical therapy plus a short course of prednisolone given orally is considered the comparator intervention. The trial is a four-armed, open-label, pragmatic RCT which uses a blinded independent clinical assessor. To provide 80 % power for each comparison, 96 participants are required in total. The pilot phase aims to recruit 40 participants. The primary clinical outcome is the proportion of patients achieving treatment success at 6 months. 'Success' is defined by a composite measure of Patient Global Assessment score of 0 or 1 on a 4-point scale plus improvement from baseline on clinical photographs scored by a clinician blinded to treatment allocation. Secondary clinical outcomes include 6-month assessment of: (1) Reduction in pain/soreness; (2) Global assessment of disease; (3) Response at other affected mucosal sites; (4) Hospital Anxiety and Depression Scale scores; (5) Sexual function; (6) Health-related quality of life using 'Short Form 36' and 'Skindex-29' questionnaires; (7) Days of topical steroid use; (8) Treatment satisfaction; (9) Discontinuation of medications due to treatment failure; (10) Per participant cost of intervention in each treatment group. Adverse events will also be reported. DISCUSSION: 'hELP' is the first RCT to address second-line treatment of ELPV. The trial has encountered unique methodological challenges and has required collaborative efforts of the UK Dermatology Clinical Trials Network alongside expert clinicians. TRIAL REGISTRATION: CURRENT CONTROLLED TRIALS: ISRCTN 81883379 . Date of registration 12 June 2014

Report from the third international consensus meeting to harmonise core outcome measures for atopic eczema/dermatitis clinical trials (HOME).

This report provides a summary of the third meeting of the Harmonising Outcome Measures for Eczema (HOME) initiative held in San Diego, CA, U.S.A., 6-7 April 2013 (HOME III). The meeting addressed the four domains that had previously been agreed should be measured in every eczema clinical trial: clinical signs, patient-reported symptoms, long-term control and quality of life. Formal presentations and nominal group techniques were used at this working meeting, attended by 56 voting participants (31 of whom were dermatologists). Significant progress was made on the domain of clinical signs. Without reference to any named scales, it was agreed that the intensity and extent of erythema, excoriation, oedema/papulation and lichenification should be included in the core outcome measure for the scale to have content validity. The group then discussed a systematic review of all scales measuring the clinical signs of eczema and their measurement properties, followed by a consensus vote on which scale to recommend for inclusion in the core outcome set. Research into the remaining three domains was presented, followed by discussions. The symptoms group and quality of life groups need to systematically identify all available tools and rate the quality of the tools. A definition of long-term control is needed before progress can be made towards recommending a core outcome measure

A comparison of the position of elite and non-elite riders during competitive show jumping

The purpose of this study was to compare the jumping positions of elite riders (within the top 150 of the British Showjumping rankings) with non-elites (unranked). Video footage of 10 elite and 10 non-elite riders jumping a one stride double combination (a vertical followed by a square oxer) within a 1.20 m competition was analysed. Four angles were measured: the angle between the trunk and the vertical (TRUNKvert), the hip angle (HIP), the angle of the thigh to the horizontal (THIGHhoriz) and the angle of the lower leg to the horizontal (LOWER LEGhoriz). Differences in the angles at five points throughout the double combination and the changes in angles between points were compared using Mann-Whitney U tests. The effect of fence (vertical versus oxer) within groups (elite and non-elite) was also compared. The level of significance was set at P&lt;0.05. HIP angle was significantly smaller on approach to the vertical (P=0.019) and significantly greater when approaching the oxer (P=0.001) for elite riders compared to non-elites. During approach to the oxer compared to the vertical elites had a greater HIP angle (P=0.007), whereas non-elites had smaller HIP (P=0.005) and THIGHhoriz (P=0.005) angles. During suspension, non-elite riders had a greater HIP (P=0.01) over the vertical and smaller LOWER LEGhoriz angle over the oxer (P=0.028) than elite riders. There were significant differences in change in HIP, THIGHhoriz and LOWER LEGhoriz angles between elite and non-elite riders between approach to and suspension over the oxer (P=0.007). During suspension, only elite riders showed an effect of fence with a greater HIP angle (P=0.005) and smaller TRUNKvert angle (P=0.013) over the oxer. Key differences in angles and change in angles exist between elite and non-elite riders. This information is useful in characterising elite rider position and identifying areas of interest for future study. </jats:p

The Use of Decision–Analytic Models in Atopic Eczema: A Systematic Review and Critical Appraisal

Objective: The objective of this systematic review was to identify and assess the quality of published economic decision–analytic models within atopic eczema against best practice guidelines, with the intention of informing future decision–analytic models within this condition. Methods: A systematic search of the following online databases was performed: MEDLINE, EMBASE, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Cochrane Central Register of Controlled Trials, Database of Abstracts of Reviews of Effects, Cochrane Database of Systematic Reviews, NHS Economic Evaluation Database, EconLit, Scopus, Health Technology Assessment, Cost-Effectiveness Analysis Registry and Web of Science. Papers were eligible for inclusion if they described a decision–analytic model evaluating both the costs and benefits associated with an intervention or prevention for atopic eczema. Data were extracted using a standardised form by two independent reviewers, whilst quality was assessed using the model-specific Philips criteria. Results: Twenty-four models were identified, evaluating either preventions (n = 12) or interventions (n = 12): 14 reported using a Markov modelling approach, four utilised decision trees and one a discrete event simulation, whilst five did not specify the approach. The majority, 22 studies, reported that the intervention was dominant or cost effective, given the assumptions and analytical perspective taken. Notably, the models tended to be short-term (16 used a time horizon of ≤1 year), often providing little justification for the limited time horizon chosen. The methodological and reporting quality of the studies was generally weak, with only seven studies fulfilling more than 50% of their applicable Philips criteria. Conclusions: This is the first systematic review of decision models in eczema. Whilst the majority of models reported favourable outcomes in terms of the cost effectiveness of the new intervention, the usefulness of these findings for decision-making is questionable. In particular, there is considerable scope for increasing the range of interventions evaluated, for improving modelling structures and reporting quality

Validity of algorithms for identifying five chronic conditions in MedicineInsight, an Australian national general practice database.

Background MedicineInsight is a database containing de-identified electronic health records (EHRs) from over 700 Australian general practices. It is one of the largest and most widely used primary health care EHR databases in Australia. This study examined the validity of algorithms that use information from various fields in the MedicineInsight data to indicate whether patients have specific health conditions. This study examined the validity of MedicineInsight algorithms for five common chronic conditions: anxiety, asthma, depression, osteoporosis and type 2 diabetes. Methods Patients’ disease status according to MedicineInsight algorithms was benchmarked against the recording of diagnoses in the original EHRs. Fifty general practices contributing data to MedicineInsight met the eligibility criteria regarding patient load and location. Five were randomly selected and four agreed to participate. Within each practice, 250 patients aged ≥ 40 years were randomly selected from the MedicineInsight database. Trained staff reviewed the original EHR for as many of the selected patients as possible within the time available for data collection in each practice. Results A total of 475 patients were included in the analysis. All the evaluated MedicineInsight algorithms had excellent specificity, positive predictive value, and negative predictive value (above 0.9) when benchmarked against the recording of diagnoses in the original EHR. The asthma and osteoporosis algorithms also had excellent sensitivity, while the algorithms for anxiety, depression and type 2 diabetes yielded sensitivities of 0.85, 0.89 and 0.89 respectively. Conclusions The MedicineInsight algorithms for asthma and osteoporosis have excellent accuracy and the algorithms for anxiety, depression and type 2 diabetes have good accuracy. This study provides support for the use of these algorithms when using MedicineInsight data for primary health care quality improvement activities, research and health system policymaking and planning

Australasian genetic counselors' attitudes toward disability and prenatal testing: Findings from a cross-sectional survey.

Diagnostic genetic testing and non-invasive prenatal testing (NIPT) for conditions associated with disability are becoming increasingly available to consumers. This genetic information can be used in the disability setting to inform factors such as prognosis, management, and reproductive decision-making. Genetic counselors (GCs) play an important role in the provision of genetic testing and NIPT, and their attitudes toward disability can influence how genetic information is communicated and shape patients' responses. This study aimed to evaluate and describe Australasian GCs' experience with and attitudes toward disabilities to identify potential biases and training needs. A cross-sectional survey was distributed to 400 GCs registered with the Human Genetics Society of Australasia. Of the 106 respondents (participation rate: 26%), a significantly greater proportion were more comfortable interacting with individuals with physical disability as compared to intellectual disability (p < 0.001). GCs with personal experiences with disabilities reported significantly greater comfort interacting with people with intellectual disability than those without experience (p = 0.012). Qualitative analysis revealed discomfort was less reflective of bias than inexperience and apprehension about communicating disrespectfully. GCs believed people with disabilities experience discrimination and that having a disability could make a person stronger, wiser, and more motivated. Most GCs viewed prenatal testing for disabilities positively as it allowed for decisions regarding continuing the pregnancy and/or provided opportunity to prepare. Challenges identified for prenatal counseling included negative societal attitudes and the low visibility of disability. GCs felt that 'personal beliefs' was the primary factor influencing the decision to terminate a pregnancy affected by disability. These findings highlight important education and training needs for GCs to improve preparedness and comfort when communicating with people with a disability