269 research outputs found

    Two-point theory for the differential self-interrogation Feynman-alpha method

    Full text link
    A Feynman-alpha formula has been derived in a two region domain pertaining the stochastic differential self-interrogation (DDSI) method and the differential die-away method (DDAA). Monte Carlo simulations have been used to assess the applicability of the variance to mean through determination of the physical reaction intensities of the physical processes in the two domains. More specifically, the branching processes of the neutrons in the two regions are described by the Chapman - Kolmogorov equation, including all reaction intensities for the various processes, that is used to derive a variance to mean relation for the process. The applicability of the Feynman-alpha or variance to mean formulae are assessed in DDSI and DDAA of spent fuel configurations.Comment: 15 pages, 5 figures. Submitted to EPJ Plu

    Ambiskew Hopf algebras

    Get PDF
    Necessary and sufficient conditions are obtained for an ambiskew polynomial algebra A over a Hopf k-algebra R to possess the structure of a Hopf algebra extending that of R, in which the added variables X+ and X- are skew primitive. The coradical filtration is calculated, many examples are described, and properties determined

    Fine-structure constant variability, equivalence principle and cosmology

    Full text link
    It has been widely believed that variability of the fine-structure constant alpha would imply detectable violations of the weak equivalence principle. This belief is not justified in general. It is put to rest here in the context of the general framework for alpha variability [J. D. Bekenstein, Phys. Rev. D 25, 1527 (1982)] in which the exponent of a scalar field plays the role of the permittivity and inverse permeability of the vacuum. The coupling of particles to the scalar field is necessarily such that the anomalous force acting on a charged particle by virtue of its mass's dependence on the scalar field is cancelled by terms modifying the usual Coulomb force. As a consequence a particle's acceleration in external fields depends only on its charge to mass ratio, in accordance with the principle. And the center of mass acceleration of a composite object can be proved to be independent of the object's internal constitution, as the weak equivalence principle requires. Likewise the widely employed assumption that the Coulomb energy of matter is the principal source of the scalar field proves wrong; Coulomb energy effectively cancels out in the continuum description of the scalar field's dynamics. This cancellation resolves a cosmological conundrum: with Coulomb energy as source of the scalar field, the framework would predict a decrease of alpha with cosmological expansion, whereas an increase is claimed to be observed. Because of the said cancellation, magnetic energy of cosmological baryonic matter is the main source of the scalar field. Consequently the expansion is accompanied by an increase in alpha; for reasonable values of the framework's sole parameter, this occurs at a rate consistent with the observers' claims.Comment: RevTeX-4, 22 pages, no figures, added a section on caveats as well as several new references with discussion of them in body. To appear in Phys. Rev.

    A comprehensive categorical and bibliometric analysis of published research articles on pediatric pain from 1975-2010

    Get PDF
    The field of pediatric pain research began in the mid-1970's and has undergone significant growth and development in recent years as evidenced by the variety of books, conferences, and journals on the topic as well as the number of disciplines engaged in work in this area. Using categorical and bibliometric meta-trend analysis, the current study offers a synthesis of research on pediatric pain published between 1975 and 2010 in peer-reviewed journals. Abstracts from 4256 articles, retrieved from Web of Science, were coded across four categories: article type, article topic, type and age of participants, and pain stimulus. The affiliation of the first author and number of citations were also gathered. The results suggest a significant increase in the number of publications over the time period investigated, with 96% of the included articles published since 1990 and most research being multi-authored publications in pain- focused journals. First authors were most often from the United States, and affiliated with a medical department. The majority of studies were original research articles; the most frequent topics were pain characterization (39.86%), pain intervention (37.49%), and pain assessment (25.00%). Clinical samples were most frequent, with participants most often characterized as children (6-12 years) or adolescents (13-18 years) experiencing chronic or acute pain. The findings provide a comprehensive overview of contributions in the field of pediatric pain research over 35 years and offers recommendations for future research in the area. (C) 2015 International Association for the Study of Pai

    User guide British Geological Survey Coastal Vulnerability Dataset (version 1)

    Get PDF
    This report describes the national scale BGS Coastal Vulnerability Dataset. The methods used to create the dataset have been critically assessed and its fitness for purpose determined by specialists in BGS. This document outlines the background to why the dataset was created, its potential uses and gives a brief description of the content. Technical information regarding the GIS and how the data was created is described and advice is provided on using the dataset

    Horizon Problem Remediation via Deformed Phase Space

    Full text link
    We investigate the effects of a special kind of dynamical deformation between the momenta of the scalar field of the Brans-Dicke theory and the scale factor of the FRW metric. This special choice of deformation includes linearly a deformation parameter. We trace the deformation footprints in the cosmological equations of motion when the BD coupling parameter goes to infinity. One class of the solutions gives a constant scale factor in the late time that confirms the previous result obtained via another approach in the literature. This effect can be interpreted as a quantum gravity footprint in the coarse grained explanation. The another class of the solutions removes the big bang singularity, and the accelerating expansion region has an infinite temporal range which overcomes the horizon problem. After this epoch, there is a graceful exiting by which the universe enters in the radiation dominated era.Comment: 13 pages, 2 figures, to appear in GER

    In Vivo Detection of Inflammation Using Pegylated Iron Oxide Particles Targeted at E-Selectin A Multimodal Approach Using MR Imaging and EPR Spectroscopy

    Get PDF
    peer reviewedObjectives: Ultrasmall particles of iron oxide (USPIO) possess superparamagnetic properties and are used as negative contrast agent in magnetic resonance imaging (MRI) because of their strong T-2 and T-2* effects. Besides this method, electron paramagnetic resonance (EPR) offers the unique capability to quantify these particles. The objective of this study was to evaluate a molecular marker for non invasive diagnosis and monitoring of inflammation. During inflammation cell adhesion molecules such as E-selectin are expressed on the endothelial cell surface. An E-selectin ligand was coupled to pegylated USPIO particles. Materials and Methods: Inflammation was induced by intramuscular injection of Freund's Complete Adjuvant in male NMRI mice. After intravenous injection of grafted or ungrafted USPIO particles, iron concentration in inflamed muscles was quantified ex vivo by X-band EPR. Particle accumulation was also assessed in vivo by L-Band EPR, as well as by T-2-Weighted MRI. Results: We determined the mean iron oxide concentration in inflamed muscles after injection of grafted or ungrafted UPSIO particles, which was 0.8% and 0.4% of the initially injected dose, respectively. By L-band EPR, we observed that the concentration of the grafted USPIO particles in inflamed muscles was twice higher than for the ungrafted particles. Using MRI experiments, a higher signal loss was clearly observed in the inflamed muscle when grafted particles were injected in comparison with the ungrafted particles. Conclusion: Even taking into account a non specific accumulation of iron oxides, the targeting of USPIO particles with E-selectin ligands significantly improved the sensitivity of detection of inflamed tissues

    The Hahn Quantum Variational Calculus

    Full text link
    We introduce the Hahn quantum variational calculus. Necessary and sufficient optimality conditions for the basic, isoperimetric, and Hahn quantum Lagrange problems, are studied. We also show the validity of Leitmann's direct method for the Hahn quantum variational calculus, and give explicit solutions to some concrete problems. To illustrate the results, we provide several examples and discuss a quantum version of the well known Ramsey model of economics.Comment: Submitted: 3/March/2010; 4th revision: 9/June/2010; accepted: 18/June/2010; for publication in Journal of Optimization Theory and Application

    Biomarkers and longitudinal changes in lumbar spine degeneration and low back pain: the Johnston County Osteoarthritis Project

    Get PDF
    Objective: To determine if baseline biomarkers are associated with longitudinal changes in the worsening of disc space narrowing (DSN), vertebral osteophytes (OST), and low back pain (LBP). Design: Paired baseline (2003–2004) and follow-up (2006–2010) lumbar spine radiographs from the Johnston County Osteoarthritis Project were graded for severity of DSN and OST. LBP severity was self-reported. Concentrations of analytes (cytokines, proteoglycans, and neuropeptides) were quantified by immunoassay. Pressure-pain threshold (PPT), a marker of sensitivity to pressure pain, was measured with a standard dolorimeter. Binary logistic regression models were used to estimate odd ratios (OR) and 95% confidence intervals (CI) of biomarker levels with DSN, OST, or LBP. Interactions were tested between biomarker levels and the number of affected lumbar spine levels or LBP. Results: We included participants (n = 723) with biospecimens, PPT, and paired lumbar spine radiographic data. Baseline Lumican, a proteoglycan reflective of extracellular matrix changes, was associated with longitudinal changes in DSN worsening (OR = 3.19 [95% CI 1.22, 8.01]). Baseline brain-derived neuropathic factor, a neuropeptide, (OR = 1.80 [95% CI 1.03, 3.16]) was associated with longitudinal changes in OST worsening, which may reflect osteoclast genesis. Baseline hyaluronic acid (OR = 1.31 [95% CI 1.01, 1.71]), indicative of systemic inflammation, and PPT (OR = 1.56 [95% CI 1.02, 2.31]) were associated with longitudinal increases in LBP severity. Conclusion: These findings suggest that baseline biomarkers are associated with longitudinal changes occurring in structures of the lumbar spine (DSN vs OST). Markers of inflammation and perceived pressure pain sensitivity were associated with longitudinal worsening of LBP

    Physiotherapy management of joint hypermobility syndrome - a focus group study of patient and health professional perspectives.

    Get PDF
    OBJECTIVE: To develop an understanding of patient and health professional views and experiences of physiotherapy to manage joint hypermobility syndrome (JHS). DESIGN: An explorative qualitative design. Seven focus groups were convened, audio recorded, fully transcribed and analysed using a constant comparative method to inductively derive a thematic account of the data. SETTING: Four geographical areas of the UK. PARTICIPANTS: 25 people with JHS and 16 health professionals (14 physiotherapists and two podiatrists). RESULTS: Both patients and health professionals recognised the chronic heterogeneous nature of JHS and reported a lack of awareness of the condition amongst health professionals, patients and wider society. Diagnosis and subsequent referral to physiotherapy services for JHS was often difficult and convoluted. Referral was often for acute single joint injury, failing to recognise the long-term multi-joint nature of the condition. Health professionals and patients felt that if left undiagnosed, JHS was more difficult to treat because of its chronic nature. When JHS was treated by health professionals with knowledge of the condition patients reported satisfactory outcomes. There was considerable agreement between health professionals and patients regarding an 'ideal' physiotherapy service. Education was reported as an overarching requirement for patients and health care professionals. CONCLUSIONS: Physiotherapy should be applied holistically to manage JHS as a long-term condition and should address injury prevention and symptom amelioration rather than cure. Education for health professionals and patients is needed to optimise physiotherapy provision. Further research is required to explore the specific therapeutic actions of physiotherapy for managing JHS
    corecore