1,721,038 research outputs found
Eurados intercomparison on emergency radiobioassay
No full textNine laboratories participated in an intercomparison exercise organised by the European Radiation Dosimetry Group (EURADOS) for emergency radiobioassay involving four high-risk radionuclides (239Pu, 241Am, 90Sr and 226Ra). Diverse methods of analysis were used by the participating laboratories for the in vitro determination of each of the four radionuclides in urine samples. Almost all the methods used are sensitive enough to meet the requirements for emergency radiobioassay derived for this project in reference to the Clinical Decision Guide introduced by the NCRP. Results from most of the methods meet the requirements of ISO 28218 on accuracy in terms of relative bias and relative precision. However, some technical gaps have been identified. For example, some laboratories do not have the ability to assay samples containing 226Ra, and sample turnaround time would be expected to be much shorter than that reported by many laboratories, as timely results for internal contamination and early decisions on medical intervention are highly desired. Participating laboratories are expected to learn from each other on the methods used to improve the interoperability among these laboratories. © The Author 2014
GHSI emergency radionuclide bioassay laboratory network: Summary of a recent exercise
No full textThe Global Health Security Initiative (GHSI) established a laboratory network within the GHSI community to develop their collective surge capacity for radionuclide bioassay in response to a radiological or nuclear emergency. A recent exercise was conducted to test the participating laboratories for their capabilities in screening and in vitro assay of biological samples, performing internal dose assessment and providing advice on medical intervention, if necessary, using a urine sample spiked with a single radionuclide, 241Am. The laboratories were required to submit their reports according to the exercise schedule and using pre-formatted templates. Generally, the participating laboratories were found to be capable with respect to rapidly screening samples for radionuclide contamination, measuring the radionuclide in the samples, assessing the intake and radiation dose, and providing advice on medical intervention. However, gaps in bioassay measurement and dose assessment have been identified. The network may take steps to ensure that procedures and practices within this network be harmonised and a follow-up exercise be organised on a larger scale, with potential participation of laboratories from the networks coordinated by the International Atomic Energy Agency and theWorld Health Organization. © The Author 2015. Published by Oxford University Press
Coordination, intermittency and trends in generalized minority games
No full textThe Minority Game framework was recently generalized to account for the possibility that agents adapt not only through strategy selection but also by diversifying their response according to the kind of dynamical regime, or the risk, they perceive. Here we study the effects of this mechanism in different information structures. We show that both the stationary macroscopic properties and the dynamical features depend strongly on whether the information supplied to the system is exogenous ('random') or endogenous ('real'). In particular, in the latter case one observes that a small amount of herding tendency suffices to alter the collective behavior dramatically. In such cases, the dynamics is characterized by the creation and destruction of trends, accompanied by intermittent features like volatility clustering. © 2005 Elsevier B.V. All rights reserved
Assessment of radioactivity in Italian baby food
No full textA set of measurements have been conducted to determine the activity-level of natural and artificial radionuclides in some baby foods commercialized in Italy. The measurements have been carried out using liquid scintillation, gamma, alpha and mass spectrometry. The activity concentrations ranged from 0.005 to 0.238, from 0.0082 to 1.65, from 0.0003 to 0.015 and from <13.6 to 233.3 Bq kg−1 for 210Po, 238U, 232Th and 40K respectively, whereas they are below the detection limit for 137Cs and 226Ra. The annual effective dose due to intake of 210Po, 238U, 232Th and 40K ranged from 280 and 800 μSv y−1 for infant 1 year old. These values lie well within the typical worldwide range of dose due to the ingestion of all natural radiation reported by UNSCEAR and they are below the internationally recommended level. This indicates that the baby food available in Italy would not pose any significant radiological impact to infant. © 2018 Elsevier Lt
Density regulation in strictly metric-free swarms
Full text linkThere is now experimental evidence that nearest-neighbour interactions in flocks of birds are metric free, i.e. they have no characteristic interaction length scale. However, models that involve interactions between neighbours that are assigned topologically are naturally invariant under spatial expansion, supporting a continuous reduction in density towards zero, unless additional cohesive interactions are introduced or the density is artificially controlled, e.g. via a finite system size. We propose a solution that involves a metric-free motional bias on those individuals that are topologically identified to be on an edge of the swarm. This model has only two primary control parameters, one controlling the relative strength of stochastic noise to the degree of co-alignment and another controlling the degree of the motional bias for those on the edge, relative to the tendency to co-align. We find a novel power-law scaling of the real-space density with the number of individuals N as well as a familiar order-to-disorder transition
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Off-equilibrium confined dynamics in a glassy system with level-crossing states
No full textWe study analytically the dynamics of a generalized p -spin model, starting with a thermalized initial condition. The model presents birth and death of states, hence the dynamics (even starting at equilibrium) may go out of equilibrium when the temperature is varied. We give a full description of this constrained out-of-equilibrium behavior and we clarify the connection to the thermodynamics by computing (subdominant) TAP states, constrained to the starting equilibrium configuration. © 2006 The American Physical Society
A comparison of different radiochemical methods applicable for the determination of plutonium isotopes in urine via alpha spectrometry
No full textMeasurement of plutonium isotopes in vivo is not feasible for radiation protection purposes. Considering the slow rate of plutonium excretion, the respect to annual dose limits, whenever risk of plutonium internal contamination occurs, implies the need of a monitoring programme based on very sensitive bioassay, i.e., measurement of plutonium content in samples of urine or feces, characterized by a very low minimum detectable activity. Alpha spectrometry is the most common measurement method applied in this field. The applicability of this method strictly depends on the procedure adopted for the sample radiochemical preparation preceding the real spectrometric counting and, particularly, on the element chemical recovery that is one of the parameters that mostly influence the minimum detectable activity achievable by the analysis. The aim of the present work is to compare the performances of four of the most widely adopted radiochemical procedures making use of different separation methods for the determination of plutonium in urine samples via alpha spectrometry
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