Estudo da suscetibilidade ao escurecimento por radiação gama de quartzo róseo-leitoso da província pegmatítica da Borborema

Este estudo considera as transformações induzidas pela radiação γ sobre os defeitos estruturais em quartzo róseo e leitoso da Província Pegmatítica da Borborema (Paraíba e Rio Grande do Norte, Brasil). Amostras de coloração rósea e leitosa foram irradiadas com doses de raios γ (60Co) entre 0,5 e 96 kGy. Defeitos pontuais relacionados às impurezas de Al, Ge, Li e grupos OH foram caracterizados por espectroscopias ultravioleta visível e infravermelha e ressonância paramagnética eletrônica, antes e após a irradiação. A espectrometria de massa com plasma indutivamente acoplado foi empregada para quantificar as concentrações de Al, Li, Ge, Fe, Ti e outras impurezas em fragmentos de diferentes tonalidades. Constatou-se que os defeitos [AlO4]0, [AlO4/H]0 e [GeO4/Li]0 são formados pela dissociação dos defeitos [AlO4/Li]0 e [Li-OH], a partir de doses de 0,5 kGy. A diminuição do sinal da ressonância paramagnética eletrônica do centro [GeO4/Li]0 e a formação de centros E'1 perturbados por Ge para doses acima de 8 kGy confirmou a grande mobilidade dos íons Li+ pela estrutura do quartzo. O aumento da população de defeitos [AlO4]0 e o consequente escurecimento das amostras foi semelhante para ambos os tipos de quartzo. Análises preliminares por microscopia eletrônica mostraram a presença de fibras nanométricas apenas no resíduo da digestão ácida de amostras róseas, indicando que a coloração rósea do quartzo da Província Pegmatítica da Borborema está provavelmente relacionada às inclusões de dumortierita

Bipolar molecular outflow of the very low-mass star Par-Lup3-4

Very low-mass stars are known to have jets and outflows, which is indicative of a scaled-down version of low-mass star formation. However, only very few outflows in very low-mass sources are well characterized. We characterize the bipolar molecular outflow of the very low-mass star Par-Lup3-4, a 0.12 M$_{\odot}$ object known to power an optical jet. We observed Par-Lup3-4 with ALMA in Bands 6 and 7, detecting both the continuum and CO molecular gas. In particular, we studied three main emission lines: CO(2-1), CO(3-2), and $^{13}$CO(3-2). Our observations reveal for the first time the base of a bipolar molecular outflow in a very low-mass star, as well as a stream of material moving perpendicular to the primary outflow of this source. The primary outflow morphology is consistent with the previously determined jet orientation and disk inclination. The outflow mass is $9.5\times10^{-7}\mathrm{M}_{\odot}$ , with an outflow rate of $4.3\times10^{-9}\mathrm{M}_{\odot}\mathrm{yr}^{-1}$ A new fitting to the spectral energy distribution suggests that Par-Lup3-4 may be a binary system. We have characterized Par-Lup3-4 in detail, and its properties are consistent with those reported in other very low-mass sources. This source provides further evidence that very low-mass sources form as a scaled-down version of low-mass stars.Comment: 20 pages, 11 figures, 5 tables. Accepted in A&

Non-invasive ventilation in obesity hypoventilation syndrome without severe obstructive sleep apnoea

Background Non-invasive ventilation (NIV) is an effective form of treatment in patients with obesity hypoventilation syndrome (OHS) who have concomitant severe obstructive sleep apnoea (OSA). However, there is a paucity of evidence on the efficacy of NIV in patients with OHS without severe OSA. We performed a multicentre randomised clinical trial to determine the comparative efficacy of NIV versus lifestyle modification (control group) using daytime arterial carbon dioxide tension (PaCO2) as the main outcome measure. Methods Between May 2009 and December 2014 we sequentially screened patients with OHS without severe OSA. Participants were randomised to NIV versus lifestyle modification and were followed for 2 months. Arterial blood gas parameters, clinical symptoms, health-related quality of life assessments, polysomnography, spirometry, 6-min walk distance test, blood pressure measurements and healthcare resource utilisation were evaluated. Statistical analysis was performed using intention-to-treat analysis. Results A total of 365 patients were screened of whom 58 were excluded. Severe OSA was present in 221 and the remaining 86 patients without severe OSA were randomised. NIV led to a significantly larger improvement in PaCO2 of -6 (95% CI -7.7 to -4.2) mm Hg versus -2.8 (95% CI -4.3 to -1.3) mm Hg, (p<0.001) and serum bicarbonate of -3.4 (95% CI -4.5 to -2.3) versus -1 (95% CI -1.7 to -0.2 95% CI) mmol/L (p<0.001). PaCO2 change adjusted for NIV compliance did not further improve the inter-group statistical significance. Sleepiness, some health-related quality of life assessments and polysomnographic parameters improved significantly more with NIV than with lifestyle modification. Additionally, there was a tendency towards lower healthcare resource utilisation in the NIV group. Conclusions NIV is more effective than lifestyle modification in improving daytime PaCO2, sleepiness and polysomnographic parameters. Long-term prospective studies are necessary to determine whether NIV reduces healthcare resource utilisation, cardiovascular events and mortality