Fe I Oscillator Strengths for the Gaia-ESO Survey

The Gaia-ESO Public Spectroscopic Survey (GES) is conducting a large-scale study of multi-element chemical abundances of some 100 000 stars in the Milky Way with the ultimate aim of quantifying the formation history and evolution of young, mature and ancient Galactic populations. However, in preparing for the analysis of GES spectra, it has been noted that atomic oscillator strengths of important Fe I lines required to correctly model stellar line intensities are missing from the atomic database. Here, we present new experimental oscillator strengths derived from branching fractions and level lifetimes, for 142 transitions of Fe I between 3526 {\AA} and 10864 {\AA}, of which at least 38 are urgently needed by GES. We also assess the impact of these new data on solar spectral synthesis and demonstrate that for 36 lines that appear unblended in the Sun, Fe abundance measurements yield a small line-by-line scatter (0.08 dex) with a mean abundance of 7.44 dex in good agreement with recent publications.Comment: Accepted for publication in Mon. Not. R. Astron. So

Reference map technique for finite-strain elasticity and fluid-solid interaction

The reference map, defined as the inverse motion function, is utilized in an Eulerian-frame representation of continuum solid mechanics, leading to a simple, explicit finite-difference method for solids undergoing finite deformations. We investigate the accuracy and applicability of the technique for a range of finite-strain elasticity laws under various geometries and loadings. Capacity to model dynamic, static, and quasi-static conditions is shown. Specifications of the approach are demonstrated for handling irregularly shaped and/or moving boundaries, as well as shock solutions. The technique is also integrated within a fluid–solid framework using a level-set to discern phases and using a standard explicit fluid solver for the fluid phases. We employ a sharp-interface method to institute the interfacial conditions, and the resulting scheme is shown to efficiently capture fluid–solid interaction solutions in several examples.United States. Dept. of Energy. Office of Science (Computational and Technology Research, contract number DE-AC02-05CH11231)National Science Foundation (U.S.) (Grant DMS-0813648)National Science Foundation (U.S.) (Mathematical Sciences Postdoctoral Research Fellowship)Natural Sciences and Engineering Research Council of Canada (NSERC Discovery Program)

A Correction Function Method for Poisson problems with interface jump conditions

In this paper we present a method to treat interface jump conditions for constant coefficients Poisson problems that allows the use of standard “black box” solvers, without compromising accuracy. The basic idea of the new approach is similar to the Ghost Fluid Method (GFM). The GFM relies on corrections applied on nodes located across the interface for discretization stencils that straddle the interface. If the corrections are solution-independent, they can be moved to the right-hand-side (RHS) of the equations, producing a problem with the same linear system as if there were no jumps, only with a different RHS. However, achieving high accuracy is very hard (if not impossible) with the “standard” approaches used to compute the GFM correction terms. In this paper we generalize the GFM correction terms to a correction function, defined on a band around the interface. This function is then shown to be characterized as the solution to a PDE, with appropriate boundary conditions. This PDE can, in principle, be solved to any desired order of accuracy. As an example, we apply this new method to devise a 4th order accurate scheme for the constant coefficients Poisson equation with discontinuities in 2D. This scheme is based on (i) the standard 9-point stencil discretization of the Poisson equation, (ii) a representation of the correction function in terms of bicubics, and (iii) a solution of the correction function PDE by a least squares minimization. Several applications of the method are presented to illustrate its robustness dealing with a variety of interface geometries, its capability to capture sharp discontinuities, and its high convergence rate.National Science Foundation (U.S.) (Grant DMS-0813648)Brazil. Coordenacao de Aperfeicoamento de Pessoal de Nivel SuperiorFulbright Program (Grant BEX 2784/06-8

Electronic structure of strongly correlated d-wave superconductors

We study the electronic structure of a strongly correlated d-wave superconducting state. Combining a renormalized mean field theory with direct calculation of matrix elements, we obtain explicit analytical results for the nodal Fermi velocity, v_F, the Fermi wave vector, k_F, and the momentum distribution, n_k, as a function of hole doping in a Gutzwiller projected d-wave superconductor. We calculate the energy dispersion, E_k, and spectral weight of the Gutzwiller-Bogoliubov quasiparticles, and find that the spectral weight associated with the quasiparticle excitation at the antinodal point shows a non monotonic behavior as a function of doping. Results are compared to angle resolved photoemission spectroscopy (ARPES) of the high temperature superconductors.Comment: final version, comparison to experiments added, 4+ pages, 4 figure

Lepidópteros tortricídeos em pomares de pomóideas e de prunóideas da Beira Interior

Comunicação apresentada no 6.º Encontro Nacional de Protecção Integrada que decorreu em Castelo Branco, na Escola Superior Agrária do Instituto Poliécnico de Castelo Branco, de 14 a 16 de Maio de 2003, no âmbito do painel sobre Prunóideas.Neste trabalho são apresentados resultados de uma prospecção relativa às espécies de tortricídeos fitófagos de pomares de pomóideas e de prunóideas, na Beira Interior. O trabalho reporta-se a dados obtidos no ano de 2002, tendo sido utilizadas armadilhas sexuais para as capturas de adultos e observação visual para a detecção de larvas. As espécies monitorizadas foram: Adoxophyes orana, Cacoecimorpha pronubana, Pandemis heparana, Pandemis ribeana (=cerasana) e Cydia molesta. Das cinco espécies monitorizadas apenas houve capturas de Cacoecimorpha pronubana e de Pandemis heparana. Relativamente a estas duas espécies são apresentadas curvas de voo. Embora tenham sido detectados frutos com a sintomatologia característica do ataque destas espécies, não foram encontradas larvas, sugerindo populações economicamente insignificantes no ano de 2002

A High-Resolution Atlas of Uranium-Neon in the H Band

We present a high-resolution (R ~ 50 000) atlas of a uranium-neon (U/Ne) hollow-cathode spectrum in the H-band (1454 nm to 1638 nm) for the calibration of near-infrared spectrographs. We obtained this U/Ne spectrum simultaneously with a laser-frequency comb spectrum, which we used to provide a first-order calibration to the U/Ne spectrum. We then calibrated the U/Ne spectrum using the recently-published uranium line list of Redman et al. (2011), which is derived from high-resolution Fourier transform spectrometer measurements. These two independent calibrations allowed us to easily identify emission lines in the hollow cathode lamp that do not correspond to known (classified) lines of either uranium or neon, and to compare the achievable precision of each source. Our frequency comb precision was limited by modal noise and detector effects, while the U/Ne precision was limited primarily by the signal-to-noise ratio (S/N) of the observed emission lines and our ability to model blended lines. The standard deviation in the dispersion solution residuals from the S/N-limited U/Ne hollow cathode lamp were 50% larger than the standard deviation of the dispersion solution residuals from the modal-noise-limited laser frequency comb. We advocate the use of U/Ne lamps for precision calibration of near-infrared spectrographs, and this H-band atlas makes these lamps significantly easier to use for wavelength calibration.Comment: 23 pages, 7 figures, submitted and accepted in ApJSS. Online-only material to be published online by ApJS

Diffusivity and configurational entropy maxima in short range attractive colloids

We study tagged particle diffusion at large packing fractions, for a model of particles interacting with a generalized Lennard-Jones 2n-n potential, with large n. The resulting short-range potential mimics interactions in colloidal systems. In agreement with previous calculations for short-range potential, we observe a diffusivity maximum as a function of temperature. By studying the temperature dependence of the configurational entropy -- which we evaluate with two different methods -- we show that a configurational entropy maximum is observed at a temperature close to that of the diffusivity maximum. Our findings suggest a relationbetween dynamics and number of distinct states for short-range potentials.Comment: 4 pages, 3 figures, submited to Physical Review Lette

Algebraic charge liquids

High temperature superconductivity emerges in the cuprate compounds upon changing the electron density of an insulator in which the electron spins are antiferromagnetically ordered. A key characteristic of the superconductor is that electrons can be extracted from them at zero energy only if their momenta take one of four specific values (the `nodal points'). A central enigma has been the evolution of the zero energy electrons in the metallic state between the antiferromagnet and the superconductor, and recent experiments yield apparently contradictory results. The oscillation of the resistance in this metal as a function of magnetic field indicate that the zero energy electrons carry momenta which lie on elliptical `Fermi pockets', while ejection of electrons by high intensity light indicates that the zero energy electrons have momenta only along arc-like regions. We present a theory of new states of matter, which we call `algebraic charge liquids', which arise naturally between the antiferromagnet and the superconductor, and reconcile these observations. Our theory also explains a puzzling dependence of the density of superconducting electrons on the total electron density, and makes a number of unique predictions for future experiments.Comment: 6+8 pages, 2 figures; (v2) Rewritten for broader accessibility; (v3) corrected numerical error in Eq. (5

Aspectos fitossanitários em olival na Beira Interior Norte e na Beira Interior Sul

Comunicação oral apresentada no 6.º Encontro Nacional de Protecção Integrada que decorreu em Castelo Branco, na Escola Superior Agrária do Instituto Politécnico de Castelo Branco, no âmbito do painel sobre o OlivalPara uma análise dos problemas fitossanitários do olival na Beira Interior foram realizados observações e estimativas do risco, em 2002, em quatro olivais na Beira Interior Norte e outros quatro na Beira Interior Sul. Os olivais da Beira Interior Norte ficam localizados nos concelhos de Seia, Pinhel, Guarda e Figueira de Castelo Rodrigo e os da Beira Interior Sul nos concelhos de Penamacor, Fundão, Proença-a-Nova e Vila Velha de Ródão. Os inimigos mais importantes e para que foram feitas estimativas do risco foram: gafa, olho de pavão, mosca-da-azeitona, traça-da-oliveira e cochonilha-negra. Em todos os olivais foram encontrados todos os inimigos avaliados, mas com pouca expressão para o olho de pavão nos olivais da cultivar Galega. Os dados da estimativa do risco são apresentados, assim como o número das intervenções químicas que foram necessárias realizar. São discutidas e comparadas as intervenções realizadas

The R Coronae Borealis stars - carbon abundances from forbidden carbon lines

Spectra of several R Coronae Borealis (RCB) stars at maximum light were examined for the [C I] 9850 A and 8727 A absorption lines. The 9850 A line is variously blended with a Fe II and CN lines but positive identifications of the [C I] line are made for R CrB and SU Tau. The 8727 A line is detected in the spectrum of the five stars observed in this wavelength region. Carbon abundances are derived from the [C I] lines using the model atmospheres and atmospheric parameters used by Asplund et al. (2000). Although the observed strength of a C I line is constant from cool to hot RCB stars, the strength is weaker than predicted by an amount equivalent to a factor of four reduction of a line's gf-value. Asplund et al. dubbed this 'the carbon problem' and discussed possible solutions. The [C I] 9850 A line seen clearly in R CrB and SU Tau confirms the magnitude of the carbon problem revealed by the C I lines. The [C I] 8727 A line measured in five stars shows an enhanced carbon problem. The gf-value required to fit the observed [C I] 8727 A line is a factor of 15 less than the well-determined theoretical gf-value. We suggest that the carbon problem for all lines may be alleviated to some extent by a chromospheric-like temperature rise in these stars. The rise far exceeds that predicted by our non-LTE calculations, and requires a substantial deposition of mechanical energy.Comment: 11 pages (embedded 5 figures and 3 tables), accepted for publication in MNRA