1,721,095 research outputs found
Antiparticles And Light Element Isotope Ions In The Earth's Magnetosphere
No full textThe ratio of positron/electron fluxes originating in nuclear reactions in the Earth's Magnetosphere is considered. It is supposed that positrons as well as electrons are mainly produced in the decay of charged pions π± → μ± → e± born in nuclear collisions of trapped relativistic inner zone protons and of cosmic rays with the residual atmosphere. These positrons and electrons are captured in the magnetosphere and create a positron and electron radiation belt of nuclear origin. The positron/electron trapped magnetospheric fluxes formed with this mechanism from radiation belt proton source are simulated and the resulting computed e+/e- flux ratio ≈ 4 appears to be in agreement with the recent observations made by the Alpha Magnetic Spectrometer (AMS) (The AMS collaboration, 1999). A > 200 MeV positron flux with an intensity about 4 times higher than the electron flux of the same energy was registered in the equatorial region at the altitude of ≈ 400 km. This ratio is significantly different from the computed ratio ≈ 1 obtained from the primary cosmic ray source through the same mechanism. As our modeling of nuclear spallation reaction shows, in the same reaction nuclei of isotopes of hydrogen and helium are also produced, which are the source of light element isotope radiation belts of D, T, 3He and 4He with a significant excess of 3He over 4He fluxes. The AMS instrument, as we have known, also looked at the distribution of helium nuclei and only 3He was observed, which is one more evidence in favor of the above hypothesis. © 2002 Elsevier Science Ltd. All rights reserved.645-6625631Barashenkov, V.S., Toneev, V.D., (1972) Interaction of Particles and Atomic Nuclei of High and Superhigh Energies with Nuclei, , Atomizdat, Moscow, Russia, 812ppBasilova, R.N., Gusev, A.A., Pugacheva, G.I., Titenkov, A.F., High energy trapped electrons in the inner radiation belt (1982) Geomagnetism and Aeronomia, 22, pp. 671-672Chen, J., Guzik, T.G., Wefel, J.P., Pyle, K.R., Cooper, J.F., Energetic helium isotopes trapped in the magnetosphere (1996) Journal of Geophysical Research, 101 (12 A), pp. 24787-24790Cornwall, J.M., Radial diffusion of ionized helium and protons: A probe for magnetospheric dynamics (1972) Journal of Geophysical Research, 77 (1 A), pp. 1756-1770Dementyev, A.V., Sobolevsky, N.M., SHIELD - Universal Monte Carlo hadron transport code: Scope and applications (1999) Radiation Measurements, 30, pp. 553-562Gusev, A.A., Kohno, T., Martin, I.M., Pugacheva, G.I., Turtelli A., Jr., Tylka, A., Kudela, K., Injection and fast radial diffusion of energetic electrons into the inner magnetosphere (1995) Planetary and Space Science, 43, pp. 1131-1136Gusev, A.A., Martin, I.M., Pugacheva, G.I., Turtelli A., Jr., Spjeldvik, W.N., Energetic positron population in the inner zone (1996) II Nuovo Cimento, 19, pp. 461-465. , Sect. CKoldashov, S.V., (1986) High Energy Electrons and Positrons in Inner Zone, , Ph.D. Thesis, Engineering-Physics Institute, Moscow, 121pp (in Russian)Letaw, J.R., Silberberg, R., Tsao, C.H., Proton nucleus total inelastic cross sections, an empirical formula for E > 10 MeV (1983) Astrophysical Journal, (SUPPL.), pp. 271-275. , Series 51Machner, H., Hidenbauer, J., Meson production close to threshold (1999) Journal of Physics G: Nuclear and Particle Physics, 25 (10), pp. 231-271Martin, I.M., Gusev, A.A., Pugacheva, G.I., Turtelli A., Jr., Mineev, Yu.V., About the origin of high energy electrons in the inner radiation belt (1995) Journal of Atmospheric and Terrestrial Physics, 57 (2), pp. 201-205Pugacheva, G.I., Spjeldvik, W.N., Gusev, A.A., Martin, On the natural energetic positron population in the inner zone of the earth (1997) Journal of Atmospheric and Solar-terrestrial Physics, 59, pp. 363-369Pugacheva, G.I., Boscher, D.M., Gusev, A.A., Martin, I.M., Spjeldvik, W.N., Numerical modeling of magnetospheric electron radial transport with accounting of synchrotron radiation losses (1998) Geophysical Research Letters, 25, pp. 1519-1522Pugacheva, G.I., Boscher, D.M., Gusev, A.A., Martin, I.M., Spjeldvik, W.N., On synchrotron radiation energy losses of trapped magnetospheric electrons (1998) Journal of Atmospheric and Solar-terrestrial Physics, 60, pp. 1159-1162Selesnick, R.S., Mewaldt, R.A., (1995) Proceedings of the Workshop in the Radiation Belts: Models and Standards, , Brussels, BelgiumSelesnick, R.S., Mewaldt, R.A., Atmospheric production of radiation belt light isotopes (1996) Journal of Geophysical Research, 101 (10 A), pp. 19745-19759Spjeldvik, W.N., Pugacheva, G.I., Gusev, A.A., Martin, I.M., Sobolevsky, N.M., Sources of inner radiation zone energetic helium ions: Cross-field transport versus in-situ nuclear reactions (1998) Advances in Space Research England, 21, pp. 1675-1678Spjeldvik, W.N., Pugacheva, G.I., Gusev, A.A., Martin, I.M., Sobolevsky, N.M., Hydrogen and helium isotope inner radiation belts in the Earth's magnetosphere (1998) Annales Geophysicae, 16, pp. 931-939Magnetic detector sees cosmic-ray anomalies (1999) CERN Courier, 39 (6), p. 6. , The AMS collaborationLeptons in near Earth's orbit (2000) Physical Letters B, 484, pp. 10-17. , The AMS collaborationVette, J.I., The NASA/national space science data center trapped radiation environment model program (TREMP) (1991) Rep. NSSDC/WDC 91-29, , NASA Goddard Space Flight Center, Greenbelt, Md., November 199
General characteristic-based algorithm for off-lattice Boltzmann simulations
No full textThe Lattice Boltzmann method offers an appealing potential for simulation of fluid flows. However, the intrinsic coupling of momentum and space discretization restricts the applicability of the traditional Lattice Boltzmann method to uniform, regular lattices which is often disadvantageous in practice. Available off-lattice Boltzmann algorithms have stability problems which are to be handled at the expense of additional computational cost. Here, we propose and validate a general characteristic-based algorithm for off-lattice Boltzmann simulations that preserves all appealing properties of the standard Lattice Boltzmann method while extending the method to unstructured grids. Both, finite-element and finite-difference implementations of the algorithms are exemplified
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Multispeed models in off-lattice Boltzmann simulations
No full textThe lattice Boltzmann method is a highly promising approach to the simulation of complex flows. Here, we realize recently proposed multispeed lattice Boltzmann models [S. Chikatamarla et al., Phys. Rev. Lett. 97 190601 (2006)] by exploiting the flexibility offered by off-lattice Boltzmann methods. The approach is based on the general characteristic-based algorithm for off-lattice Boltzmann simulations that preserves all appealing properties of the standard lattice Boltzmann method while extending the method to unstructured grids. We show that the use of multispeed models indeed gives rise to major improvements in accuracy. The suggested approach thus renders truly large-scale off-lattice Boltzmann computations practical.Process and EnergyMechanical, Maritime and Materials Engineerin
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