Rydberg structure associated with core-excited autoionizing states of the LiH radical

We have investigated inner-shell excitation of the LiH + molecular ion by electron impact within several different collision models to delineate Rydberg autoionizing resonance structure associated with the LiH + (1σ2σ 2 2 Σ + ) core-excited threshold. The minimal representation requires only the retention of the 1σ and 2σ molecular orbitals, in which the core-excited state involves the promotion of a single electron into the 2σ orbital. This model is extended to include two further representations, in which both the 3σ and 4σ orbitals obtained from a self-consistent field calculation improve target representation, correlation and support additional autoionization channels. This affects the autoionization widths and to a lesser degree the positions of the LiH (1σ2σ 2 n s, n p 1,3 Σ + ) resonance series. Comparing our work with calculations on the counterpart atomic Be system assists in the assignment of the core-excited molecular resonance states. The results from our investigation provide helpful insights into the study of inner-shell transitions produced by electron or photon impact in more complex diatomic molecules.

Dirac R -matrix calculations of electron-impact excitation of neon-like krypton

We have employed the Dirac R -matrix method to determine electron-impact excitation cross sections and effective collision strengths in Ne-like Kr 26+ . Both the configuration-interaction expansion of the target and the close-coupling expansion employed in the scattering calculation included 139 levels up through n = 5. Many of the cross sections are found to exhibit very strong resonances, yet the effects of radiation damping on the resonance contributions are relatively small. Using these collisional data along with multi-configuration Dirac–Fock radiative rates, we have performed collisional-radiative modeling calculations to determine line-intensity ratios for various radiative transitions that have been employed for diagnostics of other Ne-like ions.

An R -matrix with pseudo-states calculation of electron-impact excitation in C 2 +

We have performed an R-matrix with pseudo-states (RMPS) calculation of electron-impact excitation in C2+.Collision strengths and effective collision strengths were determined for excitation between the lowest 24 terms, including all those arising from the 2s3l and 2s4l configurations. In the RMPS calculation, 238 terms (90 spectroscopic and 148 pseudo-state) were employed in the close-coupling (CC) expansion of the target. In order to investigate the significance of coupling to the target continuum and highly excited bound states, we compare the RMPS results with those from an R-matrix calculation that incorporated all 238 terms in the configuration- interaction expansion, but only the lowest 44 spectroscopic terms in the CC expansion. We also compare our effective collision strengths with those from an earlier 12-state R-matrix calculation (Berrington et al 1989 J. Phys. B: At.Mol. Opt. Phys. 22 665). The RMPS calculation was extremely large, involving (N +1)-electron Hamiltonian matrices of dimension up to 36 085, and required the use of our recently completed suite of parallel R-matrix programs. The full set of effective collision strengths fromourRMPS calculation is available at theOakRidgeNationalLaboratoryControlledFusion Atomic Data Center web site. 1.

Electron-impact excitation of Ar 2+

Context: Emission from Ar III is seen in planetary nebulae, in H II regions, and from laboratory plasmas. The analysis of such spectra requires accurate electron impact excitation data. Aims: The aim of this work is to improve the electron impact excitation data available for Ar2+, for application in studies of planetary nebulae and laboratory plasma spectra. The effects of the new data on diagnostic line ratios are also studied. Methods: Electron-impact excitation collision strengths have been calculated using the R-Matrix Intermediate-Coupling Frame-Transformation method and the R-Matrix Breit-Pauli method. Excitation cross sections are calculated between all levels of the configurations 3s^23p^4, 3s3p^5, 3p^6, 3p^53d, and 3s^23p^3nl (3d ≤ nl ≤ 5s). Maxwellian effective collision strengths are generated from the collision strength data. Results: Good agreement is found in the collision strengths calculated using the two R-Matrix methods. The collision strengths are compared with literature values for transitions within the 3s^23p4 configuration. The new data has a small effect on Te values obtained from the I(λ7135 Å+ λ7751 Å)/ I(λ5192 Å) line ratio, and a larger effect on the Ne values obtained from the I(λ7135 Å)/I(λ9 μm) line ratio. The final effective collision strength data is archived online.

A radiation-damped R -matrix approach to the electron-impact excitation of helium-like ions for diagnostic application to fusion and astrophysical plasmas

Electron-impact excitation collision strengths for transitions between all singly excited levels up to the n = 4 shell of helium-Eke argon and the n = 4 and 5 shells of helium-like iron have been calculated using a radiation-damped R-matrix approach. The theoretical collision strengths have been examined and associated with their infinite-energy limit values to allow the preparation of Maxwell-averaged effective collision strengths. These are conservatively considered to be accurate to within 20% at all temperatures, 3 x 10(5)-3 x 10(8) K forAr(16+) and 10(6)-10(9) K for Fe24+. They have been compared with the results of previous studies, where possible, and we find a broad accord. The corresponding rate coefficients are required for use in the calculation of derived, collisional-radiative, effective emission coefficients for helium-like lines for diagnostic application to fusion and astrophysical plasmas. The uncertainties in the fundamental collision data have been used to provide a critical assessment of the expected resultant uncertainties in such derived data, including redistributive and cascade collisional-radiative effects. The consequential uncertainties in the parts of the effective emission coefficients driven by excitation from the ground levels for the key w, x, y and z lines vary between 5% and 10%. Our results remove an uncertainty in the reaction rates of a key class of atomic processes governing the spectral emission of helium-like ions in plasmas.

Helium line intensity ratio in microwave-generated plasmas

The line intensity ratio method provides a nonintrusive diagnostic for the measurement of electron temperature in microwave-generated plasmas. For optically thin plasmas of low density, a line intensity method using He I lines can often be used, and is based on the fact that the electron impact excitation rate coefficients for helium singlet and triplet states are insensitive to electron density but differ as a function of the electron temperature. Line intensity measurements are presented from microwave-generated helium plasmas. Both steady-state corona and collision-radiative theoretical models are used to evaluate the ground and excited state populations. The line ratio versus electron temperature obtained from both of these methods are compared with the results from measurements. However, it is not possible to diagnose the electron temperature from the line ratios alone due to the presence of significant opacity and nonnegligible 1s2s S-3 metastable fraction in the plasma. (C) 2004 American Institute of Physics.

Generalized collisional radiative model for light elements. Part B: Data for the Be isonuclear sequence

A first-stage collision database is assembled which contains electron-impact excitation, ionization, and recombination rate coefficients for Be, Be+, Be2+, and Be3+. The first-stage database is constructed using the R-matrix with pseudo-states, time-dependent close-coupling, and perturbative, distorted-wave methods. A second-stage collision database is then assembled which contains generalized collisional-radiative and radiated power loss coefficients. The second-stage database is constructed by solution of collisional-radiative equations in the quasi-static equilibrium approximation using the first-stage database. Both collision database stages reside in electronic form at the ORNL Controlled Fusion Atomic Data Center and in the ADAS database, and are easily accessed over the worldwide internet. © 2007 Elsevier Inc. All rights reserved.

Generalised collisional-radiative model for light elements. A: Data for the Li isonuclear sequence

A first stage collision database is assembled which contains electron-impact effective collision strengths, and ionization and recombination rate coefficients for Li, Li+, and Li2+. The first stage database is constructed using the R-matrix with pseudo-states, time-dependent close-coupling, converged close-coupling, and perturbative distorted-wave methods. A second stage collision database is then assembled which contains generalized collisional-radiative and radiated power loss coefficients. The second stage database is constructed by solution of collisional-radiative equations in the quasi-static equilibrium approximation using the first stage database. Both collision database stages reside in electronic form at the ORNL Controlled Fusion Atomic Data Center and in the ADAS database, and are easily accessed over the worldwide internet. ?? 2006 Elsevier Inc. All rights reserved.

Autonomous COLREGs Compliant Ship Navigation, Using BridgeSimulators and an Unmanned Vessel

This paper presents an approach to COLREGs compliant ship navigation. A system architecture is proposed, which will be implemented and tested on two platforms: networked bridge simulators and at sea trials using an autonomous unmanned surface vessel. Attention is paid to collision avoidance software and its risk mitigation.

Espectrometria de massa de macrociclos e dos seus aductos com o ADN

O trabalho de investigação desenvolvido teve como objectivo o estudo por espectrometria de massa com ionização por electrospray de compostos tetrapirrólicos (porfirinas e corróis) e das suas interacções com G-quadruplexes (estruturas de ADN de ordem superior, ricas em guanina). A química em fase gasosa de porfirinas catiónicas e neutras, e de corróis, foi investigada, tendo-se verificado a ocorrência de processos inesperados que foram objecto de um estudo aprofundado: redução das porfirinas catiónicas durante o processo global de electrospray e formação, na câmara de colisões, de aductos dos corróis com moléculas de água, ambos os processos detectados no modo de iões positivos. A redução das porfirinas ocorre através da formação de agregados catião-anião-solvente e catião-solvente-anião e os diferentes tipos de agregados conduzem a diferentes espécies reduzidas. A formação de aductos com água, bem como de outros iões-diagnóstico, permitiu a diferenciação dos isómeros posicionais dos corróis. Este último grupo de compostos foi igualmente estudado no modo de iões negativos. A espectrometria de massa com ionização por electrospray no modo de iões negativos foi também usada no estudo de aductos quadruplex-porfirina. Foi observada a formação de aductos do tipo [Q + nNH4+ + Pp+ -(z+n+p)H+ ]z- (Q=quadruplex, P=porfirina, p=0,1,2,3,4) para todas as porfirinas seleccionadas. A caracterização destes aductos foi efectuada através das suas decomposições induzidas por colisões. Verificou-se que o número de cargas presente nas porfirinas é um factor muito importante na estabilidade dos aductos formados, que aumenta com o aumento do número de cargas. O tipo e tamanho dos grupos substituintes presentes na porfirina não mostraram ter uma influência significativa nos processos de fragmentação. Os resultados obtidos apontam para uma ligação externa porfirina - G-quadruplex, com as porfirinas empilhadas nas extremidades dos quadruplexes.

Roberto Benjamin (org.), A fala e o gesto: ensaios de folkcomunicação sobre narrativas populares, Recife, Imprensa Universitária, 1996, 152 pp.

Apresentando como título uma paráfrase da famosa obra de Leroi-Gourham, este primeiro número da colecção “Pesquisa Académica” é uma colectânea de nove artigos/comunicações resultantes da investigação levada a cabo por Roberto Benjamim e seus alunos do curso de mestrado em comunicação rural da Universidade Federal Rural de Pernambuco. Os estudos abrangem um vasto leque de assuntos que vão desde a preocupação das metodologias de recolha, transcrição e análise de narrativas orais, à apresentação de exemplos de cartas populares pernambucanas analisadas com essa utensilagem.

Idália Farinho Custódio y Maria Aliete Farinho Galhoz, Memória tradicional de Vale Judeu, Vols. I y II, Loulé, Câmara Municipal de Loulé, 1996-1997, 356 y 457 pp.

Depois do volume dedicado aos "Contos" (saído em 2004), estamos em presença dp II vol. do "Património Oral do Concelho de Loulé.

Maria Teresa Cortez. Os contos de Grimm em Portugal. A recepção dos Kinder-und Hausmärchen entre 1837 e 1910, Coimbra, Minerva (Centro Interuniversitário de Estudos Germanísticos) e Universidade de Aveiro, 2001. 531 pp.

Trabalho que investiga a recepção dos Kinder - und Hausmärchen em Portugal, fruto duma aturada e minuciosa pesquisa documental. Com efeito, Teresa Cortez passa em revista os livros e publicações periódicas enquadrados entre 1837 — data do aparecimento das primeiras traduções de contos dos KHM, no periódico lisboeta Biblioteca Familiar e Recreativa — e 1910, data a que a autora estendeu a sua pesquisa. Cada incidência da presença dos contos dos Grimm em Portugal é cuidadosamente investigada, contextualisada e analisada, Assim, à medida que vemos surgir, primeiro esparsas em revistas destinadas a um público infantil, e sem indicação de autoria, traduções (do francês) dos KHM, vamo-nos inteirando sobre o epírito e motivações do seu aparecimento, quer partindo do estudo comparativo com o texto de origem, quer de um exame da publicação de chegada, alargando-se a pesquisa aos seus editores e autores. Todo o processo de recepção dos contos de Grimm vai sendo examinado pela autora à luz dos movimentos das últimas décadas do séc. XIX e primeira do séc. XX, nomeadamente o nacionalismo neo-romântico e o positivismo.

José Luís Forneiro, El romancero tradicional de Galicia: una poesía entre dos lenguas ("Biblioteca Mítica", 3) Oiartzun (guipuzkoa), Sendoa, 2000, 317 pp.

O estudio do romanceiro de Galicia vén merecendo unha atención especial tanto dentro como fóra do país [pénsese nas análises de A. Valenciano (1998) ou A. Requeixo (1996), entre outras].