Previously Claimed(/Unclaimed) X-ray Emission Lines in High Resolution Afterglow Spectra

We review the significance determination for emission lines in the Chandra HETGS spectrum for GRB020813, and we report on a search for additional lines in high resolution Chandra spectra. No previously unclaimed features are found. We also discuss the significance of lines sets reportedly discovered using XMM data for GRB011211 and GRB030227. We find that these features are likely of modest, though not negligible, significance.Comment: 4 pages, 1 figures, to appear in Santa Fe GRB Conference Proceedings, 200

Chandra Observations of the Optically Dark GRB030528

The X-ray-rich GRB030528 was detected by the HETE satellite and its localization was rapidly disseminated. However, early optical observations failed to detect a counterpart source. In a 2-epoch ToO observation with Chandra, we discovered a fading X-ray source likely counterpart to GRB030528. The source brightness was typical of X-ray afterglows observed at similar epochs. Other observers detected an IR source at a location consistent with the X-ray source. The X-ray spectrum is not consistent with a large absorbing column.Comment: 4 pages, 1 figures, to appear in Santa Fe GRB Conference Proceedings, 200

Optical and X-ray Observations of the Afterglow to XRF030723

The X-ray-flash XRF030723 was detected by the HETE satellite and rapidly disseminated, allowing for an optical transient to be detected ~1 day after the burst. We discuss observations in the optical with Magellan, which confirmed the fade of the optical transient. In a 2-epoch ToO observation with Chandra, we discovered a fading X-ray source spatially coincident with the optical transient. We present spectral fits to the X-ray data. We also discuss the possibility that the source underwent a rebrightening in the X-rays, as was observed in the optical. We find that the significance of a possible rebrightening is very low (~1 sigma).Comment: 4 pages, 2 figures, to appear in Santa Fe GRB Conference Proceedings, 200

Can the use of Bayesian analysis methods correct for incompleteness in electronic health records diagnosis data? Development of a novel method using simulated and real-life clinical data

Background Patient health information is collected routinely in electronic health records (EHRs) and used for research purposes, however, many health conditions are known to be under-diagnosed or under-recorded in EHRs. In research, missing diagnoses result in under-ascertainment of true cases, which attenuates estimated associations between variables and results in a bias towards the null. Bayesian approaches allow the specification of prior information to the model, such as the likely rates of missingness in the data. This paper describes a Bayesian analysis approach which aimed to reduce attenuation of associations in EHR studies focussed on conditions characterised by under-diagnosis. Methods Study 1: We created synthetic data, produced to mimic structured EHR data where diagnoses were under-recorded. We fitted logistic regression (LR) models with and without Bayesian priors representing rates of misclassification in the data. We examined the LR parameters estimated by models with and without priors. Study 2: We used EHR data from UK primary care in a case-control design with dementia as the outcome. We fitted LR models examining risk factors for dementia, with and without generic prior information on misclassification rates. We examined LR parameters estimated by models with and without the priors, and estimated classification accuracy using Area Under the Receiver Operating Characteristic. Results Study 1: In synthetic data, estimates of LR parameters were much closer to the true parameter values when Bayesian priors were added to the model; with no priors, parameters were substantially attenuated by under-diagnosis. Study 2: The Bayesian approach ran well on real life clinic data from UK primary care, with the addition of prior information increasing LR parameter values in all cases. In multivariate regression models, Bayesian methods showed no improvement in classification accuracy over traditional LR. Conclusions The Bayesian approach showed promise but had implementation challenges in real clinical data: prior information on rates of misclassification was difficult to find. Our simple model made a number of assumptions, such as diagnoses being missing at random. Further development is needed to integrated the method into studies using real-life EHR data. Our findings nevertheless highlight the importance of developing methods to address missing diagnoses in EHR data

Identifying undetected dementia in UK primary care patients: a retrospective case-control study comparing machine-learning and standard epidemiological approaches

Background Identifying dementia early in time, using real world data, is a public health challenge. As only two-thirds of people with dementia now ultimately receive a formal diagnosis in United Kingdom health systems and many receive it late in the disease process, there is ample room for improvement. The policy of the UK government and National Health Service (NHS) is to increase rates of timely dementia diagnosis. We used data from general practice (GP) patient records to create a machine-learning model to identify patients who have or who are developing dementia, but are currently undetected as having the condition by the GP. Methods We used electronic patient records from Clinical Practice Research Datalink (CPRD). Using a case-control design, we selected patients aged >65y with a diagnosis of dementia (cases) and matched them 1:1 by sex and age to patients with no evidence of dementia (controls). We developed a list of 70 clinical entities related to the onset of dementia and recorded in the 5 years before diagnosis. After creating binary features, we trialled machine learning classifiers to discriminate between cases and controls (logistic regression, naïve Bayes, support vector machines, random forest and neural networks). We examined the most important features contributing to discrimination. Results The final analysis included data on 93,120 patients, with a median age of 82.6 years; 64.8% were female. The naïve Bayes model performed least well. The logistic regression, support vector machine, neural network and random forest performed very similarly with an AUROC of 0.74. The top features retained in the logistic regression model were disorientation and wandering, behaviour change, schizophrenia, self-neglect, and difficulty managing. Conclusions Our model could aid GPs or health service planners with the early detection of dementia. Future work could improve the model by exploring the longitudinal nature of patient data and modelling decline in function over time

A novel approach to study radiation track structure with nanometer-equivalent resolution

Clustered DNA damages are considered the critical lesions in the pathways leading from the initial energy deposition by radiation to radiobiological damage. The spatial distribution of the initial DNA damage is mainly determined by radiation track-structure at the nanometer level. In this work, a novel experimental approach to image the three-dimensional structure of micrometric radiation track segments is presented. The approach utilizes the detection of single ions created in low-pressure gas. Ions produced by radiation drift towards a GEM-like 2D hole-pattern detector. When entering individual holes, ions can induce ion-impact ionization of the working-gas starting a confined electron avalanche that generates the output signal. By registering positive ions rather than electrons, diffusion is reduced and a spatial resolution of the track image of the order of water-equivalent nanometers can be achieved. Measurements and simulations to characterize the performance of a few detector designs were performed. Different cathode materials were tested and ionization cluster size distributions of 241Am alpha particles were measured. The electric field configuration in the detector was calculated to optimize the ion focusing into the detector holes. The preliminary results obtained show the directions for further development of the detector

Observation of GRB 030131 with the INTEGRAL satellite

A long Gamma-Ray Burst (GRB) was detected with the instruments on board the INTEGRAL satellite on January 31 2003. Although most of the GRB, which lasted $\sim$150 seconds, occurred during a satellite slew, the automatic software of the INTEGRAL Burst Alert System was able to detect it in near-real time. Here we report the results obtained with the IBIS instrument, which detected GRB 030131 in the 15 keV - 200 keV energy range, and ESO/VLT observations of its optical transient. The burst displays a complex time profile with numerous peaks. The peak spectrum can be described by a single power law with photon index $\Gamma\simeq$1.7 and has a flux of $\sim$2 photons cm$^{-2}$ s$^{-1}$ in the 20-200 keV energy band. The high sensitivity of IBIS has made it possible for the first time to perform detailed time-resolved spectroscopy of a GRB with a fluence of 7$\times10^{-6}$ erg cm$^{-2}$ (20-200 keV).Comment: Accepted for publication in A&A, 5 pages, 4 figures, late

Study protocol; thyroid hormone replacement for untreated older adults with subclinical hypothyroidism - a randomised placebo controlled trial (TRUST)

Background: Subclinical hypothyroidism (SCH) is a common condition in elderly people, defined as elevated serum thyroid-stimulating hormone (TSH) with normal circulating free thyroxine (fT4). Evidence is lacking about the effect of thyroid hormone treatment. We describe the protocol of a large randomised controlled trial (RCT) of Levothyroxine treatment for SCH. Methods: Participants are community-dwelling subjects aged ≥65 years with SCH, diagnosed by elevated TSH levels (≥4.6 and ≤19.9 mU/L) on a minimum of two measures ≥ three months apart, with fT4 levels within laboratory reference range. The study is a randomised double-blind placebo-controlled parallel group trial, starting with levothyroxine 50 micrograms daily (25 micrograms in subjects <50Kg body weight or known coronary heart disease) with titration of dose in the active treatment group according to TSH level, and a mock titration in the placebo group. The primary outcomes are changes in two domains (hypothyroid symptoms and fatigue / vitality) on the thyroid-related quality of life questionnaire (ThyPRO) at one year. The study has 80% power (at p = 0.025, 2-tailed) to detect a change with levothyroxine treatment of 3.0% on the hypothyroid scale and 4.1% on the fatigue / vitality scale with a total target sample size of 750 patients. Secondary outcomes include general health-related quality of life (EuroQol), fatal and non-fatal cardiovascular events, handgrip strength, executive cognitive function (Letter Digit Coding Test), basic and instrumental activities of daily living, haemoglobin, blood pressure, weight, body mass index and waist circumference. Patients are monitored for specific adverse events of interest including incident atrial fibrillation, heart failure and bone fracture. Discussion: This large multicentre RCT of levothyroxine treatment of subclinical hypothyroidism is powered to detect clinically relevant change in symptoms / quality of life and is likely to be highly influential in guiding treatment of this common condition. Trial registration: Clinicaltrials.gov NCT01660126; registered 8th June 2012

2013 AAFP Feline Vaccination Advisory Panel Report

Rationale: This Report was developed by the Feline Vaccination Advisory Panel of the American Association of Feline Practitioners (AAFP) to provide practical recommendations to help clinicians select appropriate vaccination schedules for their feline patients based on risk assessment. The recommendations rely on published data as much as possible, as well as consensus of a multidisciplinary panel of experts in immunology, infectious disease, internal medicine and clinical practice

The effects of fly-bys on planetary systems

Most of the observed extrasolar planets are found on tight and often eccentric orbits. The high eccentricities are not easily explained by planet-formation models, which predict that planets should be on rather circular orbits. Here we explore whether fly-bys involving planetary systems with properties similar to those of the gas giants in the solar system, can produce planets with properties similar to the observed planets. Using numerical simulations, we show that fly-bys can cause the immediate ejection of planets, and sometimes also lead to the capture of one or more planets by the intruder. More common, however, is that fly-bys only perturb the orbits of planets, sometimes leaving the system in an unstable state. Over time-scales of a few million to several hundred million years after the fly-by, this perturbation can trigger planet-planet scatterings, leading to the ejection of one or more planets. For example, in the case of the four gas giants of the solar system, the fraction of systems from which at least one planet is ejected more than doubles in 10^8 years after the fly-by. The remaining planets are often left on more eccentric orbits, similar to the eccentricities of the observed extrasolar planets. We combine our results of how fly-bys effect solar-system-like planetary systems, with the rate at which encounters in young stellar clusters occur. For example, we measure the effects of fly-bys on the four gas giants in the solar system. We find, that for such systems, between 5 and 15 per cent suffer ejections of planets in 10^8 years after fly-bys in typical open clusters. Thus, encounters in young stellar clusters can significantly alter the properties of any planets orbiting stars in clusters. As a large fraction of stars which populate the solar neighbourhood form in stellar clusters, encounters can significantly affect the properties of the observed extrasolar planets.Comment: 22 pages, 15 figures, 5 tables. Accepted for publication in MNRA