86,649 research outputs found
Internal Bremsstrahlung emission during 32P decay
No full textThe aim of this work is to experimentally investigate the role of Internal Bremsstrahlung (IB) in the decay of 32P, a pure β-emitter with end-point energy of 1.71 MeV and half-life of 14.28 days. IB is a continuous electromagnetic radiation occurring in β-decay, that had been widely studied in the past years. Its contribution, even if appreciable, is neglected in Monte Carlo (MC) simulation as well as in dosimetric and radiation protection calculations. Ionization current measurements were carried out using a well ionization chamber and compared with MC simulations, performed in the GAMOS (GEANT4-based Architecture for Medicine-Oriented Simulations) framework. Two experimental data sets of 32P IB spectra, taken from the literature, were used to model the IB photon spectral distribution and to include IB emission as an additional source term in MC calculation. Without IB, MC simulations underestimate up to about −18% the measured exposure, whereas the inclusion of IB according to either of the two spectra lead to differences of +2% or +8%. Consequently, the IB process is relevant for high-energy pure β-emitters such as 32P, and its contribution should be considered in all the dosimetric and radioprotection calculations
Variations on the Author
No full text“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
Relevance of Internal Bremsstrahlung for estimating the exposure to pure beta emitters
No full textAim/Introduction: β-decay is accompanied by Internal Bremsstrahlung (IB) consisting of the emission of photons showing a continuous energy spectrum. Although theoretical approaches have been developed and several measurements have been carried out for modelling the IB spectral distribution, this process is disregarded in most estimates of exposure to pure βemitters. In our recent work [1], we demonstrated that the contribution of IB to the exposure to a 90Y source can ben worth of consideration. We set up two models for the IB spectral distribution and implemented them in Monte Carlo (MC) simulations to evaluate the absorbed dose in case of external irradiation from liquid sources in vials, both without and with the emission of IB photons. We found that, depending on the chosen model, IB photons can contribute to the total absorbed dose up to 30-
60%.The aim of this study was to compare our MC simulations with radiometric measurements for a 90Y source and to extend the analysis also to other high-energy beta emitters such as 32P. Materials and Methods: We compared radiometric measurements in a well ionization chamber with Monte Carlo simulations for 32P and 90Y. MC setup was preliminarily validated by comparing measurements and simulations for 57Co, 133Ba, 137Cs and 60Co γ-emitters. Measurements were carried out using a commercial radionuclide calibrator and, for each isotope, a vial was filled with a standardized solution. MC simulations were performed using GAMOS. Concerning 32P and 90Y, a first set of MC estimates was obtained by neglecting IB photons; then, IB spectral distribution was properly modelled for each beta emitter and a second set of simulations was run including IB photons. Results: We found that MC estimates deviate up to about -15% from measurements when IB process is disregarded in simulations, while the inclusion of IB photons allows achieving a reasonable agreement thus also giving indications on the appropriate modelling of the IB spectral distribution. The obtained results outline the need to include IB
among the interaction processes to be considered when high-energy pure β-emitters are simulated. Conclusion: IB process is usually neglected when estimating the exposure to pure beta emitters. However, we demonstrated that for high-energy beta emitters such as 90Y and 32P, Internal Bremsstrahlung can play a relevant role for enhancing the absorbed dose values. For some β-emitters, the inclusion of IB in MC simulations deserves, in our opinion, consideration. References: [1] Italiano A., et al. Physica Medica 2020;76:159-65
Relevance of Internal Bremsstrahlung photons from 90Y decay: an experimental and Monte Carlo study
No full textInternal Bremsstrahlung (IB) is a continuous electromagnetic radiation accompanying beta decay; however, this process is not considered in radiation protection studies, particularly when estimating exposure from beta-decaying radionuclides. The aims of the present work are: i) to show that neglecting the IB process in Monte Carlo (MC) simulation leads to an underestimation of the energy deposited in a ionization chamber, in the case of a high-energy pure beta emitter such as Yttrium-90 (90Y), and ii) to determine the most reliable choice of source term for 90Y IB to be used in MC simulations. For this radionuclide, commonly employed in nuclear medicine and radiochemistry applications, experimental data acquired with a well ionization chamber have been compared with Monte Carlo (MC) calculations carried out in the GAMOS framework. Simulations that do not include the effect of the IB process, are found to give results underestimating the experimental values by 12–14%. Consequently, two models for the IB energy spectra, previously described by Italiano et al. [1], have been implemented using MC simulation and a good agreement has been achieved with one of them. We therefore conclude that inclusion of IB process in Monte Carlo simulation packages is advisable for a more accurate and complete treatment of electromagnetic interactions
[Newspaper Clipping: Author Claims Evidence of Second JFK Assassin #1]
No full textNewspaper article titled "Author Claims Evidence of Second JFK Assassin." The article states that author Richard J. Whalen concluded "that there is circumstantial evidence to support the theory of a second assassin in the shooting of President John F. Kennedy.
Also By The Same Author: AKTiveAuthor, a Citation Graph Approach to Name Disambiguation
No full textThe desire for definitive data and the semantic web drive for inference over heterogeneous data sources requires co-reference resolution to be performed on those data. In particular, name disambiguation is required to allow accurate publication lists, citation counts and impact measures to be determined. This paper describes a graph-based approach to author disambiguation on large-scale citation networks. Using self-citation, co-authorship and document source analyses, AKTiveAuthor clusters papers, achieving precision of 0.997 and recall of 0.818 over a test group of eight surname clusters
John F. Kennedy telegram to Roosevelt
No full textJersey Homesteads (later the Borough of Roosevelt) was established in the 1930s as an agro-industrial cooperative community. It was established specifically for urban Jewish garment workers, many of whom had emigrated from Europe. President John F. Kennedy sent a telegram to the citizens of Roosevelt, New Jersey, apologizing for not being able to attend the memorial dedication in honor of former President Franklin Delano Roosevelt. (Jersey Homesteads became Roosevelt in 1945 in honor of the president.) President Kennedy expressed his gratitude to the people of Roosevelt for constructing the memorial, and commented that it will serve as a constant reminder of Roosevelt's good works
Logarithmic variance profiles and the corresponding f-1 spectra of temperature fluctuations in turbulent Rayleigh-Bénard convection
No full textWe report experimental results for the temperature variance 2(z) and the corresponding frequency spectra P(f) in turbulent Rayleigh-Bénard convection (RBC) in a cylindrical sample of aspect ratioT= D/L = 1:00 (D = 1:12 m is the diameter and L = 1:12 m the height). The measurements were conducted in the Rayleigh-number range 1011 < Ra < 1:35 1014 and Pr ' 0:8. For Ra = 1:35x1014, 2(z) could be described well by a logarithmic dependence on the vertical position z in a range of z 1 < z < z 2 with z 1 ' 70 and z 2 = 0:1L. Here L=(2Nu) is the thickness of a thin thermal sublayer adjacent to the horizontal plate where the heat flux (denoted by the Nusselt number Nu) is carried mostly by thermal diffusion. In the log layer, we found that the temperature spectra had a significant frequency range over which P(f) f with close to 1. As Ra decreased, increased so that the log layer became thinner. At Ra = 2:05 1011, z 2 < z 1 and therefore there was no range for a log layer. Correspondingly, the temperature spectrum near the horizontal plate did not have the f1 scaling form either
Maine author Franklin F. Gould recalls his first glimpse of the outside world
No full textMaine author Franklin F. Gould recalls his first glimpse of the outside world as he relates how, as a young farm boy in the late 1800\u27s, he drove his father\u27s horses on an errand to an icebound river
Mapping the Discipline of the Olympic Games An Author-Cocitation Analysis
No full textThe authors conducted an author cocitation analysis on prominent authors writing about the Olympics during the 1990s. Author cocitation is an established bibliometric technique that can be used to measure the relative similarities of topics written about by the cited authors. This enables a visual representation of the “intellectual space” of the discipline, in this case the Olympics, to be created for the period under review. So core and peripheral research areas are identified, along with their major contributors. The representation appears as a two-dimensional cluster-enhanced map. Subject expertise was then applied to the results to place labels on the generated clusters of authors and their topics
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