Chemical composition of the stellar cluster Gaia1: No surprise behind Sirius

Indexación: Web of Science; Scopus.We observed six He-clump stars of the intermediate-Age stellar cluster Gaia1 with the MIKE/Magellan spectrograph. A possible extra-galactic origin of this cluster, recently discovered thanks to the first data release of the ESA Gaia mission, has been suggested, based on its orbital parameters. Abundances for Fe, α, proton-And neutron-capture elements have been obtained. We find no evidence of intrinsic abundance spreads. The iron abundance is solar ([FeI/H] = + 0.00 ± 0.01; σ = 0.03 dex). All the other abundance ratios are generally solar-scaled, similar to the Galactic thin disk and open cluster stars of similar metallicity. The chemical composition of Gaia1 does not support an extra-galactic origin for this stellar cluster, which can be considered as a standard Galactic open cluster.https://www.aanda.org/articles/aa/abs/2017/07/aa31009-17/aa31009-17.htm

Planar Josephson Tunnel Junctions in an Asymmetric Magnetic Field

We analyze the consequences resulting from the asymmetric boundary conditions imposed by a non-uniform external magnetic field at the extremities of a planar Josephson tunnel junction and predict a number of testable signatures. When the junction length $L$ is smaller than its Josephson penetration depth $\lambda_j$, static analytical calculations lead to a Fresnel-like magnetic diffraction pattern, rather than a Fraunhofer-like one typical of a uniform field. Numerical simulations allow to investigate intermediate length ($L\approx \lambda_j$) and long ($L>\lambda_j$) junctions. We consider both uniform and $\delta$-shaped bias distributions. We also speculate on the possibility of exploiting the unique static properties of this system for basic experiments and devices.Comment: 9 pages, 3 figure

Plasmons in Sodium under Pressure: Increasing Departure from Nearly-Free-Electron Behavior

We have measured plasmon energies in Na under high pressure up to 43 GPa using inelastic x-ray scattering (IXS). The momentum-resolved results show clear deviations, growing with increasing pressure, from the predictions for a nearly-free electron metal. Plasmon energy calculations based on first-principles electronic band structures and a quasi-classical plasmon model allow us to identify a pressure-induced increase in the electron-ion interaction and associated changes in the electronic band structure as the origin of these deviations, rather than effects of exchange and correlation. Additional IXS results obtained for K and Rb are addressed briefly.Comment: 5 pages, 4 figure

Tachoastrometry: astrometry with radial velocities

Spectra of composite systems (e.g., spectroscopic binaries) contain spatial information that can be retrieved by measuring the radial velocities (i.e., Doppler shifts) of the components in four observations with the slit rotated by 90 degrees in the sky. By using basic concepts of slit spectroscopy we show that the geometry of composite systems can be reliably retrieved by measuring only radial velocity differences taken with different slit angles. The spatial resolution is determined by the precision with which differential radial velocities can be measured. We use the UVES spectrograph at the VLT to observe the known spectroscopic binary star HD 188088 (HIP 97944), which has a maximum expected separation of 23 milli-arcseconds. We measure an astrometric signal in radial velocity of 276 \ms, which corresponds to a separation between the two components at the time of the observations of 18 $\pm2$ milli-arcseconds. The stars were aligned east-west. We describe a simple optical device to simultaneously record pairs of spectra rotated by 180 degrees, thus reducing systematic effects. We compute and provide the function expressing the shift of the centroid of a seeing-limited image in the presence of a narrow slit.The proposed technique is simple to use and our test shows that it is amenable for deriving astrometry with milli-arcsecond accuracy or better, beyond the diffraction limit of the telescope. The technique can be further improved by using simple devices to simultaneously record the spectra with 180 degrees angles.With tachoastrometry, radial velocities and astrometric positions can be measured simultaneously for many double line system binaries in an easy way. The method is not limited to binary stars, but can be applied to any astrophysical configuration in which spectral lines are generated by separate (non-rotational symmetric) regions.Comment: Accepted for publication in A&

Isotope Spectroscopy

The measurement of isotopic ratios provides a privileged insight both into nucleosynthesis and into the mechanisms operating in stellar envelopes, such as gravitational settling. In this article, we give a few examples of how isotopic ratios can be determined from high-resolution, high-quality stellar spectra. We consider examples of the lightest elements, H and He, for which the isotopic shifts are very large and easily measurable, and examples of heavier elements for which the determination of isotopic ratios is more difficult. The presence of 6Li in the stellar atmospheres causes a subtle extra depression in the red wing of the 7Li 670.7 nm doublet which can only be detected in spectra of the highest quality. But even with the best spectra, the derived $^6$Li abundance can only be as good as the synthetic spectra used for their interpretation. It is now known that 3D non-LTE modelling of the lithium spectral line profiles is necessary to account properly for the intrinsic line asymmetry, which is produced by convective flows in the atmospheres of cool stars, and can mimic the presence of 6Li. We also discuss briefly the case of the carbon isotopic ratio in metal-poor stars, and provide a new determination of the nickel isotopic ratios in the solar atmosphere.Comment: AIP Thinkshop 10 "High resolution optical spectroscopy", invited talk, AN in pres

Alimentação de Liposarcus anisitsi e Potamorhina squamoralevis, peixes abundantes na Baía Tuiuiú, Pantanal, Mato Grosso do Sul, Brasil.

Os grandes sistemas fluviais da América do Sul abrigam uma grande diversidade de espécies de peixes, que obtém o alimento nas mais diversas fontes. Este trabalho visou identificar e analisar a composição da dieta de Liposarcus anisitsi e Potamorhina squamoralevis, espécies abundantes na baía Tuiuiú, Pantanal, Mato Grosso do Sul. Foram realizadas coletas bimestrais, durante três anos, na baía Tuiuiú, meandro abandonado do rio Paraguai. Dos exemplares coletados foram retirados os tratos digestivos e o conteúdo foi homogeneizado e diluído diversas vezes para facilitar a leitura e identificação dos itens alimentares que foi efetuada sob microscópio. As duas espécies apresentaram o detrito/sedimento como principal item alimentar. Além dos detritos, L. anisitsi ingeriu quantidades expressivas de restos de vegetais e algas. P. squamoralevis ingeriu quantidades significativas de algas e restos de vegetais são menos importantes na sua dieta. Também foram ingeridos outros itens, em menor proporção. Na baía Tuiuiú, P. squamoralevis e L. anisitsi podem ser classificados como espécies especializadas, uma vez que se alimentam principalmente de detrito/sedimento, com alguma tendência a generalistas, já que podem se alimentar também de outros itens alimentares associados a detritos. As espécies utilizam diferentes micro-hábitats na captura do alimento o que possibilita a sua coexistência. Devido à sua abundância e frequência de ocorrência, os peixes detritívoros constituem a base da cadeia alimentar aquática na baía Tuiuiú. The major river systems of South America have a great diversity of fish species, which feed on a great diversity of food sources. This study aimed to identify and analyze the composition of the feeding of Liposarcus anisitsi and Potamorhina squamoralevis, abundants in the Tuiuiú bay, Pantanal, Mato Grosso do Sul State. Samples were collected bimonthly during three years in the Tuiuiú bay, an oxbow lake the Paraguay river. From the specimens were taken the digestive tracts and the contents were homogenized and diluted several times to facilitate the reading and identification of food items that was performed under microscope. In both fish species, the detritus / sediment were the main food item. L. anisitsi ingested large amounts of plant debris and algae. P. squamoralevis ingested significant amounts of algae; plant remains are less important in the diet of this species. Other items were also eaten in smaller proportions. In the Tuiuiú bay, P. squamoralevis and L. anisitsi can be classified as specialized species, since they feed mainly on detritus / sediment, with some degree to generalism, since it can feed also on other food items. L. anisitsi and P. squamoralevis use different microhabitats to capture food which allow them to coexist. Due to its abundance and frequency of occurrence, detritus feeding fishes are the basis of the aquatic food chain in the Tuiuiú bay

Protein-DNA/RNA Interactions: An Overview of Investigation Methods in the -Omics Era

The fields of application of functional proteomics are not limited to the study of protein-protein interactions; they also extend to those involving protein complexes that bind DNA or RNA. These interactions affect fundamental processes such as replication, transcription, and repair in the case of DNA, as well as transport, translation, splicing, and silencing in the case of RNA. Analytical or preparative experimental approaches, both in vivo and in vitro, have been developed to isolate and identify DNA/RNA binding proteins by exploiting the advantage of the affinity shown by these proteins toward a specific oligonucleotide sequence. The present review proposes an overview of the approaches most commonly employed in proteomics applications for the identification of nucleic acid-binding proteins, such as affinity purification (AP) protocols, EMSA, chromatin purification methods, and CRISPR-based chromatin affinity purification, which are generally associated with mass spectrometry methodologies for the unbiased protein identification

High Resolution HDS/SUBARU chemical abundances of the young stellar cluster Palomar 1

Context. Palomar\,1 is a peculiar globular cluster (GC). It is the youngest Galactic GC and it has been tentatively associated to several of the substructures recently discovered in the Milky Way (MW), including the Canis Major (CMa) overdensity and the Galactic Anticenter Stellar Structure (GASS). Aims. In order to provide further insights into its origin, we present the first high resolution chemical abundance analysis for one red giant in Pal\,1. Methods. We obtained high resolution (R=30000) spectra for one red giant star in Pal\,1 using the High Dispersion Spectrograph (HDS) mounted at the SUBARU telescope. We used ATLAS-9 model atmospheres coupled with the SYNTHE and WIDTH calculation codes to derive chemical abundances from the measured line equivalent widths of 18 among $\alpha$, Iron-peak, light and heavy elements. Results. The Palomar~1 chemical pattern is broadly compatible to that of the MW open clusters population and similar to disk stars. It is, instead, remarkably different from that of the Sagittarius (Sgr) dwarf spheroidal galaxy. Conclusions. If Pal\,1 association with either CMa or GASS will be confirmed, this will imply that these systems had a chemical evolution similar to that of the Galactic disk.Comment: 13 pages, 9 figures, 5 tables. Accepted for publication in Astronomy and Astrophysics. Minor changes in the tex

Current concepts in nanostructured contrast media development for In vivo photoacoustic imaging

Photoacoustic (PA) imaging is indeed one of the most promising bioimaging techniques for theranostics applications in humans, allowing for the visualization of blood vessels and melanomas with high spatial resolution. However, in order to overcome the endogenous contrast arising from interfering endogenous species such as haemoglobin and melanin, specific contrast agents need to be developed, allowing PAI to successfully identify targeted contrast in the range of wavelengths in which interference from the biomatrix is minimized. This has been first performed by small molecule dyes, which, however, suffer from some important limitations such as low hydrophilicity and short circulation times. For this reason, scientific research has recently directed its efforts towards the development of nanostructured contrast agents capable of providing efficient PA contrast at low concentrations with low toxicity and high biocompatibility. The principal nanostructures are based on (1) metal and semiconducting nanoparticles, amongst which variously shaped nano-gold plays the main role, (2) carbon nanomaterials, such as carbon nanotubes and graphene, and (3) conjugated polymer nanoparticles. In this review, the principal characteristics of this class of materials are reported and greater focus is directed towards in vivo studies. A detailed analysis is performed on various physical-chemical parameters that define the PA response of reported contrast agents, like absorption coefficients and photoacoustic efficiencies. By comparing the experimental data, this review provides a comprehensive tool for the evaluation of new nanostructured contrast agents for PA imaging

Resezioni polmonari limitate “intenzionali” versus lobectomie nel trattamento dei tumori polmonari periferici non microcitomi allo stadio IA

Scopo del presente studio è valutare, attraverso l’analisi retrospettiva della nostra casistica e la revisione della letteratura, se le resezioni polmonari limitate siano equivalenti alla lobectomia nel trattamento dei tumori polmonari non microcitomi (NSCLC) periferici allo stadio IA (T1N0M0), in termini di radicalità oncologica, sopravvivenza e tasso di recidive locali, regionali e sistemiche.Viene inoltre preso in considerazione l’impatto delle resezioni limitate, rispetto alle resezioni lobari, sulla funzionalità polmonare postoperatoria. Pazienti e metodi. Abbiamo analizzato una serie consecutiva di 36 pazienti, 28 uomini e 8 donne, di età compresa fra 61 e 81 anni (media 73 anni), sottoposti ad intervento chirurgico, nel periodo compreso fra gennaio 2000 e dicembre 2003, per NSCLC periferici T1N0M0; sono state effettuate 11 resezioni limitate e 25 lobectomie. Sono state analizzate comparativamente sopravvivenza e recidive (follow-up 3-5 anni), nonché le prove di funzionalità respiratoria ad un anno dall’intervento. Risultati. La sopravvivenza a 3 e 5 anni è stata pari all’88% ed all’82% nel gruppo dei pazienti sottoposti a resezioni limitate, al 93% e all’88% nel gruppo dei pazienti sottoposti a lobectomia. Si è verificata una recidiva locale (9%) nel primo gruppo, una (4%) nel secondo. Ad un anno dall’intervento si sono osservati un moderato decremento del volume espiratorio forzato in 1 secondo (FEV1) e della capacità di diffusione per monossido di carbonio (DLCO) nei pazienti sottoposti a resezione lobare, e un sostanziale mantenimento dei parametri funzionali preoperatori, eccezion fatta per la DLCO, nei pazienti sottoposti a resezione limitata. Conclusioni. La nostra circoscritta esperienza, in accordo con le tendenze attuali della letteratura, indica che l’intervento di resezione polmonare limitata, in pazienti selezionati, con NSCLC periferici allo stadio IA, rappresenta una valida alternativa alla lobectomia in termini di sopravvivenza e tasso di recidiva, determinando altresì un minor decremento della funzionalità polmonare postoperatoria. La segmentectomia può essere dunque considerata, in tali casi, procedura chirurgica di scelta, anche in pazienti in grado di tollerare una resezione maggior