HD 65949: Rosetta Stone or Red Herring

HD 65949 is a late B star with exceptionally strong Hg II at 3984[A], but it is not a typical HgMn star. The Re II spectrum is of extraordinary strength. Abundances, or upper limits are derived here for 58 elements based on a model with Teff = 13100K, and log(g) = 4.0. Even-Z elements through nickel show minor deviations from solar abundances. Anomalies among the odd-Z elements through copper are mostly small. Beyond the iron peak, a huge scatter is found. The abundance pattern of the heaviest elements resembles the N=126 r-process peak of solar material, though not in detail. We find a significant correlation of the abundance excesses with second ionization potentials for elements with Z > 30. This indicates the relevance of photospheric or near-photospheric processes. We explore a model with mass accretion of exotic material followed by the more commonly accepted differentiation by diffusion. That model leads to a number of predictions which challenge future work. Likely primary and secondary masses are near 3.3 and 1.6 M(solar), with a separation of ca. 0.25 AU. New atomic structure calculations are presented in two appendices.Comment: Accepted by MNRAS: 16 pages, 5 figure

The FERRUM project: Transition probabilities for forbidden lines in [FeII] and experimental metastable lifetimes

Accurate transition probabilities for forbidden lines are important diagnostic parameters for low-density astrophysical plasmas. In this paper we present experimental atomic data for forbidden [FeII] transitions that are observed as strong features in astrophysical spectra. Aims: To measure lifetimes for the 3d^6(^3G)4s a ^4G_{11/2} and 3d^6(^3D)4s b ^4D_{1/2} metastable levels in FeII and experimental transition probabilities for the forbidden transitions 3d^7 a ^4F_{7/2,9/2}- 3d^6(^3G)4s a ^4G_{11/2}. Methods: The lifetimes were measured at the ion storage ring facility CRYRING using a laser probing technique. Astrophysical branching fractions were obtained from spectra of Eta Carinae, obtained with the Space Telescope Imaging Spectrograph onboard the Hubble Space Telescope. The lifetimes and branching fractions were combined to yield absolute transition probabilities. Results: The lifetimes of the a ^4G_{11/2} and the b ^4D_{1/2} levels have been measured and have the following values, 0.75(10) s and 0.54(3) s respectively. Furthermore, we have determined the transition probabilities for two forbidden transitions of a ^4F_{7/2,9/2}- a ^4G_{11/2} at 4243.97 and 4346.85 A. Both the lifetimes and the transition probabilities are compared to calculated values in the literature.Comment: 5 pages, accepted for publication in A&

Rare-earth elements in the atmosphere of the magnetic chemically peculiar star HD 144897. New classification of the Nd III spectrum

We have obtained a UVES spectrum of a slowly rotating strongly magnetic Ap star, HD 144897, that exhibits very large overabundances of rare-earth elements. Here we present a detailed spectral analysis of this object, also taking into account effects of non-uniform vertical distribution (stratification) of chemical elements. We have determined the photospheric abundances of 40 ions. For seven elements (Mg, Si, Ca, Ti, Cr, Mn, Fe), we have obtained a stratification model that allow us to produce a satisfactory fit to the observed profiles of spectral lines of various strength. REEs abundances, that for the first time in the literature have been determined from the lines of the first and second ions, have been found typically four dex larger than solar abundances. Our analysis of REE spectral lines provide a strong support to the laboratory line classification and determination of the atomic parameters. The only remarkable exception is Nd III, for which spectral synthesis was found to be inconsistent with the observations. We have therefore performed a revision of the Nd III classification. We have confirmed the energies for 11 out of 24 odd energy levels classified previously, and we have derived the energies for additional 24 levels of Nd III, thereby increasing substantially the number of classified Nd III lines with corrected wavelengths and atomic parameters.Comment: 22 pages; accepted by A&

Ionization Structure and Spectra of Iron in Gaseous Nebulae}

The emission spectra and the ionization structure of the low ionization stages of iron, Fe I--IV, in gaseous nebulae are studied. This work includes: (i) new atomic data: photoionization cross sections, total e-ion recombination rates, excitation collision strengths, and transition probabilities; (ii) detailed study of excitation mechanisms for the [Fe II], [Fe III], and [Fe IV] emission, and spectroscopic analysis of the observed IR, optical, and UV spectra; (iii) study of the physical structure and kinematics of the nebulae and their ionization fronts. Spectral analysis of the well observed Orion nebula is carried out as a test case, using extensive collisional-radiative and photoionization models. It is shown that the [Fe II] emission from the Orion nebula is predominantly excited via electron collisions in high density partially ionized zones; radiative fluorescence is relatively less effective. Further evidence for high density zones is derived from the [O I] and [Ni II] spectral lines, as well as from the kinematic measurements of ionic species in the nebula. The ionization structure of iron in Orion is modeled using the newly calculated atomic data, showing some significant differences from previous models. The new model suggests a fully ionized H II region at densities on the order of $10^3$ cm$^{-3}$, and a dynamic partially ionized H II/H I region at densities of $10^5-10^7$ \cm3. Photoionization models also indicate that the optical [O I] and [Fe II] emission originates in high density partially ionized regions within ionization fronts. The gas phase iron abundance in Orion is estimated from observed spectra.Comment: AAS LaTex, 60 pages 18 figures. Astrophysical Journal. in pres

Detection of Mitochondrial COII DNA Sequences in Ant Guts as a Method for Assessing Termite Predation by Ants

Termites and ants contribute more to animal biomass in tropical rain forests than any other single group and perform vital ecosystem functions. Although ants prey on termites, at the community level the linkage between these groups is poorly understood. Thus, assessing the distribution and specificity of ant termitophagy is of considerable interest.We describe an approach for quantifying ant-termite food webs by sequencing termite DNA (cytochrome c oxidase subunit II, COII) from ant guts and apply this to a soil-dwelling ant community from tropical rain forest in Gabon. We extracted DNA from 215 ants from 15 species. Of these, 17.2% of individuals had termite DNA in their guts, with BLAST analysis confirming the identity of 34.1% of these termites to family level or better. Although ant species varied in detection of termite DNA, ranging from 63% (5/7; Camponotus sp. 1) to 0% (0/7; Ponera sp. 1), there was no evidence (with small sample sizes) for heterogeneity in termite consumption across ant taxa, and no evidence for species-specific ant-termite predation. In all three ant species with identifiable termite DNA in multiple individuals, multiple termite species were represented. Furthermore, the two termite species that were detected on multiple occasions in ant guts were in both cases found in multiple ant species, suggesting that anttermite food webs are not strongly compartmentalised. However, two ant species were found to consume only Anoplotermes-group termites, indicating possible predatory specialisation at a higher taxonomic level. Using a laboratory feeding test, we were able to detect termite COII sequences in ant guts up to 2 h after feeding, indicating that our method only detects recent feeding events. Our data provide tentative support for the hypothesis that unspecialised termite predation by ants is widespread and highlight the use of molecular approaches for future studies of ant-termite food webs

Epidemiology of Invasive Fungal Infections in Latin America

The pathogenic role of invasive fungal infections (IFIs) has increased during the past two decades in Latin America and worldwide, and the number of patients at risk has risen dramatically. Working habits and leisure activities have also been a focus of attention by public health officials, as endemic mycoses have provoked a number of outbreaks. An extensive search of medical literature from Latin America suggests that the incidence of IFIs from both endemic and opportunistic fungi has increased. The increase in endemic mycoses is probably related to population changes (migration, tourism, and increased population growth), whereas the increase in opportunistic mycoses may be associated with the greater number of people at risk. In both cases, the early and appropriate use of diagnostic procedures has improved diagnosis and outcome

PrimPol-dependent single-stranded gap formation mediates homologous recombination at bulky DNA adducts

Stalled replication forks can be restarted and repaired by RAD51-mediated homologous recombination (HR), but HR can also perform post-replicative repair after bypass of the obstacle. Bulky DNA adducts are important replication-blocking lesions, but it is unknown whether they activate HR at stalled forks or behind ongoing forks. Using mainly BPDE-DNA adducts as model lesions, we show that HR induced by bulky adducts in mammalian cells predominantly occurs at post-replicative gaps formed by the DNA/RNA primase PrimPol. RAD51 recruitment under these conditions does not result from fork stalling, but rather occurs at gaps formed by PrimPol re-priming and resection by MRE11 and EXO1. In contrast, RAD51 loading at double-strand breaks does not require PrimPol. At bulky adducts, PrimPol promotes sister chromatid exchange and genetic recombination. Our data support that HR at bulky adducts in mammalian cells involves post-replicative gap repair and define a role for PrimPol in HR-mediated DNA damage tolerance

New Labour?new renaissance

This paper explores the term ?urban renaissance? in relation to the historiography of the Renaissance of the 15th and 16th centuries in Italy. It examines the place of the Renaissance in cultural history and considers how it has, since its inception, been utilised by writers to reflect on the present. The paper situates the urban renaissance within the context of New Labour rhetoric at the time of the Millennium. It argues that the idea of renaissance can, in this instance, be connected to a kind of millenarianism that was reflected in public rhetoric regarding the city and in a number of building projects