86,581 research outputs found
Updating standard solar models
No full textWe present an updated version of our standard solar model (SSM) where helium and heavy elements diffusion is included and the improved OPAL equation of state (Rogers 1994; Rogers et al. 1996) is used. In such a way the EOS is consistent with the adopted opacity tables, from the same Livermore group, an occurrence which should further enhance the reliability of the model. The results for the physical characteristics and the neutrino production of our SSM are discussed and compared with previous works on the matter
Heavy element diffusion and globular cluster ages
No full textThis paper discusses low mass, metal poor stars, presenting new evolutionary computations which take into account the inward diffusion of both He and heavy elements during the H burning phase. The investigation has been extended to He burning models, discussing the luminosity of the Zero Age Horizontal Branch (ZAHB) models originated from progenitors with efficient element diffusion. We find that diffusion of heavy elements plays a non-negligible role in the evolutionary paths of the model. One finds that element diffusion has a sensitive influence on evolutionary models, a less significant effect on the isochrone turn off and, finally, a rather marginal impact on the difference in luminosity between the ZAHB and the isochrone Turn-Off (TO). The consequences of these results on current evaluations of globular cluster ages are discussed in connection with possible sources of errors
A theoretical approach to globular cluster low main sequence stars
No full textThis paper present new evolutionary computations extending toward the lower main sequence previous computations given for globular cluster stars. We discuss the physical inputs with particular regard to the limit of the adopted usual treatment of the stellar atmosphere, which allows a tight correlation with actual stellar structures only for selected ran of masses, depending on the assumed metallicity. Theoretical evolutionary properties of Very Low Mass (VLM) stars are presented and discussed. We find that adopting new extended tabulations of radiative opacity, as computed according to Alexander & Fergusson (1994) procedures and by relying on the Saumon & Chabrier (1992) equation of state (EOS) our results allow a reasonable fitting of HST observation of metal poor VLM objects in the galactic globular NGC 6397. The investigation has been extended to a sample of held VLM star with known parallaxes, showing again a satisfactory agreement with the distribution of metal poor dwarfs and discussing the present theoretical scenario for solar metallicity VLM. Selected evolutionary quantities are presented in suitable tables for metal poor objects (Y = 0.23, Z = 0.0001, 0.0003, 0.0006 and 0.001). A brief discussion including a comparison of mass-luminosity relations for VLM objects for the various investigated metallicities closes the paper
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
Cosmic-ray discrimination capabilities of DE/dx silicon nuclear telescopes using neural networks
No full text[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.
Particle classification capabilities of a silicon dE/dX detector using neural networks
No full textThe classification capabilities of light nuclei by a silicon detector measuring up to 32 dE/dX samples of their energy release have been investigated taking into account ionization fluctuations and electronic noise in signal response. The detector has been described as a telescope made of silicon wafers, 6 x 6 cm(2) wide and 380 mu m thick, having tracking capability. It represents the detector used in the NINA space mission, devoted to measure low-energy light nuclei composition in space on a polar orbit at 700 km altitude. The nuclei classification is performed by a neural algorithm (NN) of the Multi Layer Perceptron type, having 32 input neurons. This approach ensures that all measured information is used for event classification. Data sets consisting of several classes of nuclei - from hydrogen to higher Z and mass numbers - have been simulated, both for training and test of the NN. The robustness of this classification approach, against fluctuations and noise, has been investigated using classification efficiency and contamination as merit figures. Results are presented for contained particle, in the energy interval from the lower threshold for triggering up to 30 silicon layers interested; namely, from about 10 MeV for protons to some hundred MeV for higher nuclei. (C) 1998 Published by Elsevier Science B,V. All rights reserved. RI Cafagna, Francesco/A-9299-201
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
Il trattamento delle lesioni epatiche primitive e secondarie con termoablazione mediante radiofrequenza
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