Gemini spectra of 12000K white dwarf stars

We report signal-to-noise ratio SNR ~ 100 optical spectra for four DA white dwarf stars acquired with the GMOS spectrograph of the 8m Gemini north telescope. These stars have 18<g<19 and are around Teff ~ 12000 K, were the hydrogen lines are close to maximum. Our purpose is to test if the effective temperatures and surface gravities derived from the relatively low signal-to-noise ratio ( ~ 21) optical spectra acquired by the Sloan Digital Sky Survey through model atmosphere fitting are trustworthy. Our spectra range from 3800A to 6000A, therefore including H beta to H9. The H8 line was only marginally present in the SDSS spectra, but is crucial to determine the gravity. When we compare the values published by Kleinman et al. (2004) and Eisenstein et al. (2006) with our line-profile (LPT) fits, the average differences are: Delta Teff ~ 320 K, systematically lower in SDSS, and Delta log g ~ 0.24 dex, systematically larger in SDSS. The correlation between gravity and effective temperature can only be broken at wavelengths bluer than 3800 A. The uncertainties in Teff are 60% larger, and in log g larger by a factor of 4, than the Kleinman et al. (2004) and Eisenstein et al. (2006) internal uncertainties.Comment: 11 pages and 8 figure

Relationship between the stability and surface tension of the tear film

FCT, QREN and FEDER/COMPETE through CFUM

Relationships between Brewer-Dobson circulation, double tropopauses, ozone and stratospheric water vapour

Statistical relationships between the variability of the area covered by double tropopause events (DTs), the strength of the tropical upwelling, the total column ozone and of the lower stratospheric water vapour are analyzed. The QBO and ENSO signals in the double tropopause and tropical upwelling as well as their influence on the statistical relationships are also presented. The analysis is based on both reanalysed data (ERA-Interim) and satellite data. Significant anticorrelations were found between the area covered by DTs and the total column ozone in the midlatitudes of the Northern Hemisphere. This relationship is confirmed by a large positive correlation between the areas covered by ozone laminae and double tropopause events as found in the HIRDLS satellite dataset. Significant anticorrelations were also found between the global area of double tropopause events and the near global (50◦S–50◦N) water vapour in the lower stratosphere. The correlations of DT variables with total column ozone and ozone laminae are both consistent with the poleward displacement of tropical air with lower ozone mixing ratio and with tropospheric intrusions of tropical tropospheric air into the lower extratropical stratosphere. The association of DTs with the poleward displacements of the tropical air is also consistent with a strong positive correlation between the area covered by DTs and the wave activity in the lower most stratosphere, between the first and second lapse rate tropopauses, as found in the ERA-Interim reanalysis. Finally, a significant anticorrelation was found between the tropical upwelling and the near global lower stratospheric water vapour. Moreover, the step like decrease in the lower stratospheric water vapour after 2001 is mirrored by a step like increase in the tropical upwelling.publishe

Supramolecular dehydropeptide hydrogels: synthesis, properties and biomedical applications

Self-assembled low molecular weight peptide hydrogels have emerged in recent years as the new paradigm in biomaterials research due to their high water content; fully organic struc-ture; intrinsic nontoxicity and biocompatibility and fibrillar nanostructure indicative of the ex-tracellular matrix.1 The properties of peptide hydrogels can be tuned by design and there is a large variety of possible hydrogelator structures using proteinogenic and non proteinogenic aminoacids. Our research group has recently described a series of self-assembled hydrogels based on dehydrodipeptides N-protected with an aromatic moiety. The C-terminal dehy-droaminoacid residue (dehydrophenylalanine, dehydroaminobutyric acid and dehydroalanine) is prone to make the peptide resistant to prote-olysis and restrains the conformational freedom of the peptide.2 In this work the preparation and characterization of the new hydrogelators as well as the corresponding hydrogels will be presented together with some biomedical appli-cations of the new biomaterials prepared name-ly as drug delivery systems or as plataforms for theragnostics.This work was supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding of CQUM (UID/QUI/00686/2016) and CF-UM-UP (UID/FIS/04650/2013 and UID/FIS/04650/ 2019), FEDER, PORTUGAL2020 and COMPETE2020 are also acknowledged for funding under the research projects PTDC/QUI-QFI/28020/2017 (POCI-01-0145-FEDER-028020) and PTDC/QUI-QOR/29015/ 2017 (POCI-01-0145-FEDER-029015)

Evaluación de la transmitancia en lentes de contacto con diferentes potencias

[Extracto] Justificación y objetivos - Cuando la luz atraviesa cualquier material absorbente, su intensidad disminuye y esta variación puede ser dependiente de factores como la potencia, la espessura y el coeficiente de absorción del material de la lente de contacto (LC). Evaluación de la influencia de la potencia en la transmitancia de lentes de contacto , en diferentes regiones del espectro electromagnético: Visible (400-700 nm), UVA (315-400 nm), UVB (280-315 nm) y UVC (230-280 nm). [...]info:eu-repo/semantics/publishedVersio

Sacrococcygeal Teratoma: From Diagnosis to Surgery

Os teratomas sacrococcígeos (TSC) são os tumores mais frequentes do recém-nascido, sendo frequentemente diagnosticados in utero. Apresenta-se o caso de um recém-nascido com um volumoso TSC, diagnosticado às 22 semanas de gestação. A gravidez foi vigiada por uma equipa multidisciplinar, atendendo ao elevado risco de complicações materno-fetais. Realizou-se cesariana electiva às 38 semanas. Ao 8º dia de vida, procedeu-se à ressecção cirúrgica do TSC em bloco com o cóccix e reposicionamento posterior do ânus. Não existiram intercorrências no intra ou pós-operatório. O seguimento da gravidez por uma equipa pluridisciplinar foi fulcral, per - mitindo a vigilância de complicações, planeamento anestésico-cirúrgico do nascimento e antecipação do tratamento apropriado, nomeadamente dos cuidados perinatais e da cirurgia neonatal

Discovery of an ultramassive pulsating white dwarf

We announce the discovery of the most massive pulsating hydrogen-atmosphere (DA) white dwarf (WD) ever discovered, GD 518. Model atmosphere fits to the optical spectrum of this star show it is a 12,030 +/- 210 K WD with a log(g) = 9.08 +/- 0.06, which corresponds to a mass of 1.20 +/- 0.03 Msun. Stellar evolution models indicate that the progenitor of such a high-mass WD endured a stable carbon-burning phase, producing an oxygen-neon-core WD. The discovery of pulsations in GD 518 thus offers the first opportunity to probe the interior of a WD with a possible oxygen-neon core. Such a massive WD should also be significantly crystallized at this temperature. The star exhibits multi-periodic luminosity variations at timescales ranging from roughly 425-595 s and amplitudes up to 0.7%, consistent in period and amplitude with the observed variability of typical ZZ Ceti stars, which exhibit non-radial g-mode pulsations driven by a hydrogen partial ionization zone. Successfully unraveling both the total mass and core composition of GD 518 provides a unique opportunity to investigate intermediate-mass stellar evolution, and can possibly place an upper limit to the mass of a carbon-oxygen-core WD, which in turn constrains SNe Ia progenitor systems.Comment: 5 pages, 3 figures, Astrophysical Journal Letters, 771, L2 (2013

The pulsating DA white dwarf star EC 14012-1446: results from four epochs of time-resolved photometry

The pulsating DA white dwarfs are the coolest degenerate stars that undergo self-driven oscillations. Understanding their interior structure will help to understand the previous evolution of the star. To this end, we report the analysis of more than 200 h of time-resolved CCD photometry of the pulsating DA white dwarf star EC 14012-1446 acquired during four observing epochs in three different years, including a coordinated three-site campaign. A total of 19 independent frequencies in the star's light variations together with 148 combination signals up to fifth order could be detected. We are unable to obtain the period spacing of the normal modes and therefore a mass estimate of the star, but we infer a fairly short rotation period of 0.61 +/- 0.03 d, assuming the rotationally split modes are l=1. The pulsation modes of the star undergo amplitude and frequency variations, in the sense that modes with higher radial overtone show more pronounced variability and that amplitude changes are always accompanied by frequency variations. Most of the second-order combination frequencies detected have amplitudes that are a function of their parent mode amplitudes, but we found a few cases of possible resonantly excited modes. We point out the complications in the analysis and interpretation of data sets of pulsating white dwarfs that are affected by combination frequencies of the form f_A+f_B-f_C intruding into the frequency range of the independent modes.Comment: 14 pages, 6 figures, 6 tables. MNRAS, in pres

Environmental risk assessment in a contaminated estuary: an integrated weight of evidence approach as a decision support tool

Environmental risk assessment of complex ecosystems such as estuaries is a challenge, where innovative and integrated approaches are needed. The present work aimed at developing an innovative integrative methodology to evaluate in an impacted estuary (the Sado, in Portugal, was taken as case study), the adverse effects onto both ecosystem and human health. For the purpose, new standardized lines of evidence based on multiple quantitative data were integrated into a weight of evidence according to a best expert judgment approach. The best professional judgment for a weight of evidence approach in the present study was based on the following lines of evidence: i) human contamination pathways; ii) human health effects: chronic disease; iii) human health effects: reproductive health; iv) human health effects: health care; v) human exposure through consumption of local agriculture produce; vi) exposure to contaminated of water wells and agriculture soils; vii) contamination of the estuarine sedimentary environment (metal and organic contaminants); viii) effects on benthic organisms with commercial value; and ix) genotoxic potential of sediments. Each line of evidence was then ordinally ranked by levels of ecological or human health risk, according to a tabular decision matrix and expert judgment. Fifteen experts scored two fishing areas of the Sado estuary and a control estuarine area, in a scale of increasing environmental risk and management actions to be taken. The integrated assessment allowed concluding that the estuary should not be regarded as impacted by a specific toxicant, such as metals and organic compounds hitherto measured, but by the cumulative risk of a complex mixture of contaminants. The proven adverse effects on species with commercial value may be used to witness the environmental quality of the estuarine ecosystem. This method argues in favor of expert judgment and qualitative assessment as a decision support tool to the integrative management of estuaries. Namely it allows communicating environmental risk and proposing mitigation measures to local authorities and population under a holistic perspective as an alternative to narrow single line of evidence approaches, which is mandatory to understand cause and effect relationships in complex areas like estuaries.info:eu-repo/semantics/publishedVersio