2,085 research outputs found

    Evaluation of vaccine effectiveness in older adults using routinely collected data: a quasi-experimental approach

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    Vaccination of older adults is a key component of public health policy, but further evidence is required to understand its effectiveness in practice. Electronic health records (EHRs) present a potential alternative to the gold-standard evidence of clinical trials, particularly for populations, such as older adults, who may be under-represented in trials due to ethical and practical constraints in recruitment. Importantly, EHRs also allow the real-world study of an intervention as it is delivered in practice, and its effect in clinically important sub-groups. However, EHRs are not purposed to collect informaton on confounders, which may bias results from the analyisis of routinely-collected data. This motivated my review of quasi-experimental (QE) methods as a means of indirectly adjusting for confounding. My published methodological review found that the longitudinal information available in EHRs offer many opportunities for mitigating against confounding bias, but many methods may be under-utilised. The prior event rate ratio (PERR) and its alternative formulation, described under the Pairwise framework, is a recently developed method that utilises longitudinal information. This before-and-after approach can be applied to rate and survival data, allowing an easy comparison to many trial results. The data on vaccination in UK older adults was also the basis for further study of the performance and limitations of the method beyond exisiting simulation studies. Through comparison to weighted regression, I demonstrated how the source of confounding and robustness of the results could be explored. In a novel application of the PERR and Pairwise methods to interactions, I investigated the effectiveness of the pneumococcal vaccine in older patients, and found evidence for an increase in effectiveness with age across the years of policy implementation, 2003-2005. In my investigation of the influenza vaccine in annual cohorts from 1997 to 2011, I found consistent evidence of a moderately protective effect against myocardial infarction, but that this may decrease with age. The evidence also indicated a protective effect against influenza itself, but no age trend in its effectiveness was detected

    Co-Determination in West Germany - Through the Best (and Worst) of Times

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    Separating true range measurements from multi-path and scattering interference in commercial range cameras

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    Time-of-flight range cameras acquire a three-dimensional image of a scene simultaneously for all pixels from a single viewing location. Attempts to use range cameras for metrology applications have been hampered by the multi-path problem, which causes range distortions when stray light interferes with the range measurement in a given pixel. Correcting multi-path distortions by post-processing the three-dimensional measurement data has been investigated, but enjoys limited success because the interference is highly scene dependent. An alternative approach based on separating the strongest and weaker sources of light returned to each pixel, prior to range decoding, is more successful, but has only been demonstrated on custom built range cameras, and has not been suitable for general metrology applications. In this paper we demonstrate an algorithm applied to both the Mesa Imaging SR-4000 and Canesta Inc. XZ-422 Demonstrator unmodified off-the-shelf range cameras. Additional raw images are acquired and processed using an optimization approach, rather than relying on the processing provided by the manufacturer, to determine the individual component returns in each pixel. Substantial improvements in accuracy are observed, especially in the darker regions of the scene

    Studies in Clinical Psychology

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    The manuscript of which this issue is the first part, contains studies by nine graduate students made under the direction of Dr. George A. Kelly, Director of the Fort Hays State College Clinic, and consists of 243 pages. The manuscript will be published in three or four parts.https://scholars.fhsu.edu/fort_hays_studies_series/1046/thumbnail.jp

    Discovering Valuable Items from Massive Data

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    Suppose there is a large collection of items, each with an associated cost and an inherent utility that is revealed only once we commit to selecting it. Given a budget on the cumulative cost of the selected items, how can we pick a subset of maximal value? This task generalizes several important problems such as multi-arm bandits, active search and the knapsack problem. We present an algorithm, GP-Select, which utilizes prior knowledge about similarity be- tween items, expressed as a kernel function. GP-Select uses Gaussian process prediction to balance exploration (estimating the unknown value of items) and exploitation (selecting items of high value). We extend GP-Select to be able to discover sets that simultaneously have high utility and are diverse. Our preference for diversity can be specified as an arbitrary monotone submodular function that quantifies the diminishing returns obtained when selecting similar items. Furthermore, we exploit the structure of the model updates to achieve an order of magnitude (up to 40X) speedup in our experiments without resorting to approximations. We provide strong guarantees on the performance of GP-Select and apply it to three real-world case studies of industrial relevance: (1) Refreshing a repository of prices in a Global Distribution System for the travel industry, (2) Identifying diverse, binding-affine peptides in a vaccine de- sign task and (3) Maximizing clicks in a web-scale recommender system by recommending items to users

    The impact of myosteatosis on outcomes following surgery for gastrointestinal malignancy: a meta-analysis.

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    INTRODUCTION: The aim of this review was to evaluate the impact of preoperative myosteatosis on long-term outcomes following surgery for gastrointestinal malignancy. METHODS: We conducted a systematic search of the electronic information sources, including PubMed MEDLINE, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), CINAHL and AMED. Studies were included if they reported the impact of preoperatively defined myosteatosis, or a similar term, on long-term survival outcomes following surgery for gastrointestinal malignancy. A subgroup analysis was performed for those studies reporting outcomes for colorectal cancer patients only. FINDINGS: Thirty-nine full-text articles were reviewed for inclusion, with 19 being retained after the inclusion criteria were applied. The total number of included patients across all studies was 14,481. Patients with myosteatosis had significantly poorer overall survival, according to univariate (hazard ratio (HR) 1.82, 95% confidence interval (CI) 1.67-1.99) and multivariable (HR 1.66, 95% CI 1.49-1.86) analysis. This was also demonstrated for cancer-specific survival (univariate HR 1.62, 95% CI 1.18-2.22; multivariable HR 1.73, 95% CI 1.48-2.03) and recurrence-free survival (univariate HR 1.28, 95% CI 1.10-1.48; multivariable HR 1.38, 95% CI 1.07-1.77). CONCLUSIONS: This meta-analysis demonstrates that patients with preoperative myosteatosis have poorer long-term survival outcomes following surgery for gastrointestinal malignancy. Therefore, myosteatosis should be used for preoperative optimisation and as a prognostic tool before surgery. More standardised definitions of myosteatosis and further cohort studies of patients with non-colorectal malignancies are required

    Wakefield-Induced Ionization injection in beam-driven plasma accelerators

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    We present a detailed analysis of the features and capabilities of Wakefield-Induced Ionization (WII) injection in the blowout regime of beam driven plasma accelerators. This mechanism exploits the electric wakefields to ionize electrons from a dopant gas and trap them in a well-defined region of the accelerating and focusing wake phase, leading to the formation of high-quality witness-bunches [Martinez de la Ossa et al., Phys. Rev. Lett. 111, 245003 (2013)]. The electron-beam drivers must feature high-peak currents (Ib0≳8.5 kAI_b^0\gtrsim 8.5~\mathrm{kA}) and a duration comparable to the plasma wavelength to excite plasma waves in the blowout regime and enable WII injection. In this regime, the disparity of the magnitude of the electric field in the driver region and the electric field in the rear of the ion cavity allows for the selective ionization and subsequent trapping from a narrow phase interval. The witness bunches generated in this manner feature a short duration and small values of the normalized transverse emittance (kpσz∌kpÏ”n∌0.1k_p\sigma_z \sim k_p\epsilon_n \sim 0.1). In addition, we show that the amount of injected charge can be adjusted by tuning the concentration of the dopant gas species, which allows for controlled beam loading and leads to a reduction of the total energy spread of the witness beams. Electron bunches, produced in this way, fulfil the requirements to drive blowout regime plasma wakes at a higher density and to trigger WII injection in a second stage. This suggests a promising new concept of self-similar staging of WII injection in steps with increasing plasma density, giving rise to the potential of producing electron beams with unprecedented energy and brilliance from plasma-wakefield accelerators

    Useful applications of earth-oriented satellites - Systems for remote-sensing information and distribution, panel 8

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    Problems and potential use of data gathered by remote sensing from satellites or aircraf
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