Spitzer IRS observations of k plus a galaxies: a link between polycyclic aromatic hydrocarbon emission properties and active galactic nucleus feedback?

We have performed Spitzer InfraRed Spectrograph (IRS) low-resolution 5-12 mu m spectroscopy on a sample of galaxies selected to be at three distinct poststarburst evolutionary stages based on their optical spectral indices. The resulting IRS spectra show distinctive polycyclic aromatic hydrocarbon (PAH) emission line structures at 6.2, 7.7, 8.6, and 11.3 mu m and little silicate absorption, indicative of ongoing star formation. However, the PAH interline ratios, in particular the 11.3/6.2 mu m and 7.7/6.2 mu m ratio, show large variations. These variations are found to correlate with both time since the most recent starburst and active galactic nucleus (AGN) activity. We speculate that the evolution observed in these PAH ratios is related to an increase in AGN activity with time since starburst

Systematic review and meta-analysis of optimal P2Y₁₂ blockade in dual antiplatelet therapy for patients with diabetes with acute coronary syndrome

Background: Patients with diabetes are at increased risk of acute coronary syndromes (ACS) and their mortality and morbidity outcomes are significantly worse following ACS events, independent of other comorbidities. This systematic review sought to establish the optimum management strategy with focus on P2Y₁₂ blockade in patients with diabetes with ACS. Methods: MEDLINE (1946 to present) and EMBASE (1974 to present) databases, abstracts from major cardiology conferences and previously published systematic reviews were searched to June 2014. Relevant randomised control trials with clinical outcomes for P2Y₁₂ inhibitors in adult patients with diabetes with ACS were scrutinised independently by 2 authors with applicable data was extracted for primary composite end point of cardiovascular death, myocardial infarction (MI) and stroke; enabling calculation of relative risks with 95% CI with subsequent direct and indirect comparison. Results: Four studies studied clopidogrel in patients with diabetes, with two (3122 patients) having primary outcome data showing superiority of clopidogrel against placebo with RR0.84 (95% CI 0.72–0.99). Irrespective of management strategy, the newer agents prasugrel (2 studies) and ticagrelor (1 study) had a lower primary event rate compared with clopidogrel; RR 0.80 (95% CI 0.66 to 0.97) and RR 0.89 (95% CI 0.77 to 1.02), respectively. When ticagrelor was indirectly compared with prasugrel, there was a trend to an improved primary outcome with prasugrel (RR 1.11 (95% CI 0.94 to 1.31)) particularly in those managed with percutaneous coronary intervention (PCI) (RR 1.23 (95% CI 0.95 to 1.59)). Prasugrel demonstrated a statistical superiority with prevention of further MI with RR 1.48 (95% CI 1.11 to 1.97). This was not at the expense of increased major thrombolysis in MI (TIMI) bleeding rates RR 0.94 (95% CI 0.59 to 1.51). Conclusions: This meta-analysis shows the addition of a P2Y₁₂ inhibitor is superior to placebo, with a trend favouring the use of prasugrel in patients with diabetes with ACS, particularly those undergoing PCI

Orbital Evolution of Moons in Weakly Accreting Circumplanetary Disks

We investigate the formation of hot and massive circumplanetary disks (CPDs) and the orbital evolution of satellites formed in these disks. Because of the comparatively small size-scale of the sub-disk, quick magnetic diffusion prevents the magnetorotational instability (MRI) from being well-developed at ionization levels that would allow MRI in the parent protoplanetary disk. In the absence of significant angular momentum transport, continuous mass supply from the parental protoplanetary disk leads to the formation of a massive CPD. We have developed an evolutionary model for this scenario and have estimated the orbital evolution of satellites within the disk. We find, in a certain temperature range, that inward migration of a satellite can be stopped by a change in the structure due to the opacity transitions. Moreover, by capturing second and third migrating satellites in mean motion resonances, a compact system in Laplace resonance can be formed in our disk models.Comment: 10 pages, 9 figure

Lie point symmetries and the geodesic approximation for the Schr\"odinger-Newton equations

We consider two problems arising in the study of the Schr\"odinger-Newton equations. The first is to find their Lie point symmetries. The second, as an application of the first, is to investigate an approximate solution corresponding to widely separated lumps of probability. The lumps are found to move like point particles under a mutual inverse-square law of attraction

Three-Dimensional Propagation of Magnetohydrodynamic Waves in Solar Coronal Arcades

We numerically investigate the excitation and temporal evolution of oscillations in a two-dimensional coronal arcade by including the three-dimensional propagation of perturbations. The time evolution of impulsively generated perturbations is studied by solving the linear, ideal magnetohydrodynamic (MHD) equations in the zero-beta approximation. As we neglect gas pressure the slow mode is absent and therefore only coupled MHD fast and Alfven modes remain. Two types of numerical experiments are performed. First, the resonant wave energy transfer between a fast normal mode of the system and local Alfven waves is analyzed. It is seen how, because of resonant coupling, the fast wave with global character transfers its energy to Alfvenic oscillations localized around a particular magnetic surface within the arcade, thus producing the damping of the initial fast MHD mode. Second, the time evolution of a localized impulsive excitation, trying to mimic a nearby coronal disturbance, is considered. In this case, the generated fast wavefront leaves its energy on several magnetic surfaces within the arcade. The system is therefore able to trap energy in the form of Alfvenic oscillations, even in the absence of a density enhancement such as that of a coronal loop. These local oscillations are subsequently phase-mixed to smaller spatial scales. The amount of wave energy trapped by the system via wave energy conversion strongly depends on the wavelength of perturbations in the perpendicular direction, but is almost independent from the ratio of the magnetic to density scale heights.Comment: 27 pages, 11 figure

Cosmic bulk viscosity through backreaction

We consider an effective viscous pressure as the result of a backreaction of inhomogeneities within Buchert's formalism. The use of an effective metric with a time-dependent curvature radius allows us to calculate the luminosity distance of the backreaction model. This quantity is different from its counterpart for a "conventional" spatially flat bulk viscous fluid universe. Both expressions are tested against the SNIa data of the Union2.1 sample with only marginally different results for the distance-redshift relation and in accordance with the $\Lambda$CDM model. Future observations are expected to be able to discriminate among these models on the basis of indirect measurements of the curvature evolution.Comment: 18 pages, 6 figures, comments and references added, accepted for publication in GR