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Instituto Superior Técnico
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About: Instituto Superior Técnico is a based out in . It is known for research contribution in the topics: Catalysis & Finite element method. The organization has 10085 authors who have published 30226 publications receiving 667524 citations. The organization is also known as: IST & Instituto Superior Tecnico.
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TL;DR: In this paper, the authors reviewed the kinetic modeling of low-pressure (p ∼ 1−10 torr) stationary nitrogen discharges and the corresponding afterglows and showed that a good description of the overall behavior of nitrogen plasmas requires a deep understanding of the coupling between different kinetics.
Abstract: The kinetic modeling of low-pressure (p ∼ 1−10 torr) stationary nitrogen discharges and the corresponding afterglows is reviewed. It is shown that a good description of the overall behavior of nitrogen plasmas requires a deep understanding of the coupling between different kinetics. The central role is played by ground-state vibrationally excited molecules, N2(X 1 Σ + g ,v ), which have a strong influence on the shape of the electron energy distribution function, on the creation and destruction of electronically excited states, on the gas heating, dissociation and on afterglow emissions. N2(X 1 Σ + ,v ) molecules are actually the hinge ensuring a strong link between the various kinetics. The noticeable task done by electronically excited metastable molecules, in particular N2(A 3 Σ + u )a nd N2(a � 1 Σ − u ), is also pointed out. Besides contributing to the same phenomena as vibrationally excited molecules, these electronic metastable states play also a categorical role in ionization. Furthermore, vibrationally excited molecules in high v levels are in the origin of the peaks observed in the flowing afterglow for the concentrations of several species, such as N2(A 3 Σ + ), N2(B 3 Πg), N + 2 (B 2 Σ + u ) and electrons, which occur downstream from the discharge after a dark zone as a consequence of the V-V up-pumping mechanism.
212 citations
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TL;DR: This work proves the following theorem: axisymmetric, stationary solutions of the Einstein field equations formed from classical gravitational collapse of matter obeying the null energy condition, that are everywhere smooth and ultracompact must have at least two light rings, and one of them is stable.
Abstract: We prove the following theorem: axisymmetric, stationary solutions of the Einstein field equations formed from classical gravitational collapse of matter obeying the null energy condition, that are everywhere smooth and ultracompact (i.e., they have a light ring) must have at least two light rings, and one of them is stable. It has been argued that stable light rings generally lead to nonlinear spacetime instabilities. Our result implies that smooth, physically and dynamically reasonable ultracompact objects are not viable as observational alternatives to black holes whenever these instabilities occur on astrophysically short time scales. The proof of the theorem has two parts: (i) We show that light rings always come in pairs, one being a saddle point and the other a local extremum of an effective potential. This result follows from a topological argument based on the Brouwer degree of a continuous map, with no assumptions on the spacetime dynamics, and, hence, it is applicable to any metric gravity theory where photons follow null geodesics. (ii) Assuming Einstein's equations, we show that the extremum is a local minimum of the potential (i.e., a stable light ring) if the energy-momentum tensor satisfies the null energy condition.
212 citations
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TL;DR: In this paper, resurgence and transseries are used to encode the complete large-order asymptotic behaviour of the coefficients from a perturbative expansion, generically in terms of (multi) instanton sectors and for each problem in terms with its Stokes constants, which are recast in equivalent physical languages: either a statistical mechanical language, as motions in chains and lattices; or a conformal field theoretical language, with underlying Virasoro-like algebraic structures.
211 citations
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TL;DR: In this article, the use of rare earth (Ce, La) salts and bis-sulphur silane (BTESPT) as chromate substitutes for galvanized steel was investigated.
211 citations
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TL;DR: Al Almela, Daniel Alejandro as discussed by the authors, Federación Nacional de Investigaciones Cientificas y Tecnicas (FNCIT) and CONGESTO NACIONAL de Investigación Científicas (CICIT) of Argentina.
Abstract: Fil: Almela, Daniel Alejandro. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Parque Centenario. Instituto de Tecnologias en Deteccion y Astroparticulas; Argentina
211 citations
Authors
Showing all 10288 results
Name | H-index | Papers | Citations |
---|---|---|---|
Joao Seixas | 153 | 1538 | 115070 |
A. Gomes | 150 | 1862 | 113951 |
Amartya Sen | 149 | 689 | 141907 |
António Amorim | 136 | 1477 | 96519 |
Joao Varela | 133 | 1411 | 92438 |
Pietro Faccioli | 132 | 1378 | 89795 |
João Carvalho | 126 | 1278 | 77017 |
Pedro Jorge | 124 | 776 | 68658 |
Pedro Silva | 124 | 961 | 74015 |
A. De Angelis | 118 | 534 | 54469 |
Hermine Katharina Wöhri | 116 | 629 | 55540 |
Helena Santos | 114 | 1058 | 54286 |
P. Conde Muiño | 109 | 558 | 56133 |
Joao Saraiva | 107 | 519 | 53340 |
J. N. Reddy | 106 | 926 | 66940 |