Universidade Federal de Santa Catarina

About: Universidade Federal de Santa Catarina is a education organization based out in Florianópolis, Brazil. It is known for research contribution in the topics: Population & Context (language use). The organization has 28408 authors who have published 55433 publications receiving 714461 citations.

Warm ionized gas in CALIFA early-type galaxies - 2D emission-line patterns and kinematics for 32 galaxies

Abstract: Context. The morphological, spectroscopic, and kinematical properties of the warm interstellar medium (wim ) in early-type galaxies (ETGs) hold key observational constraints to nuclear activity and the buildup history of these massive, quiescent systems. High-quality integral field spectroscopy (IFS) data with a wide spectral and spatial coverage, such as those from the CALIFA survey, offer an unprecedented opportunity for advancing our understanding of the wim in ETGs. Aims. This article centers on a 2D investigation of the wim component in 32 nearby (≲150 Mpc) ETGs from CALIFA, complementing a previous 1D analysis of the same sample.Methods. The analysis presented here includes Hα intensity and equivalent width (EW) maps and radial profiles, diagnostic emission-line ratios, and ionized-gas and stellar kinematics. It is supplemented by τ -ratio maps, which are a more efficient means to quantify the role of photoionization by the post-AGB stellar component than alternative mechanisms (e.g., AGN, low-level star formation).Results. Confirming and strengthening our previous conclusions, we find that ETGs span a broad continuous sequence in the properties of their wim , exemplified by two characteristic classes. The first (type i) comprises systems with a nearly constant EW(Hα ) in their extranuclear component, which quantitatively agrees with (but is no proof of) the hypothesis that photoionization by the post-AGB stellar component is the main driver of extended wim emission. The second class (type ii) stands for virtually wim -evacuated ETGs with a very low (≤0.5 A), outwardly increasing EW(Hα ). These two classes appear indistinguishable from one another by their LINER-specific emission-line ratios in their extranuclear component. Here we extend the tentative classification we proposed previously by the type i+, which is assigned to a subset of type i ETGs exhibiting ongoing low-level star-forming activity in their periphery. This finding along with faint traces of localized star formation in the extranuclear component of several of our sample galaxies points to a non-negligible contribution by OB stars to the global ionizing photon budget in ETGs. Additionally, our data again highlight the diversity of ETGs in their gaseous and stellar kinematics. While in one half of our sample, gas and stars show similar (yet not necessarily identical) velocity patterns that are both dominated by rotation along the major galaxy axis, our analysis also documents several cases of kinematical decoupling between gas and stars, or rotation along the minor galaxy axis. We point out that the generally very low (≲1 A) EW(Hα ) of ETGs requires a careful quantitative assessment of potential observational and analysis biases in studies of their wim . With standard emission-line fitting tools, Balmer emission lines become progressively difficult to detect below an EW (Hα ) ~ 3 A, therefore our current understanding of the presence and 2D emission patterns and kinematics of the diffuse wim ETGs may be severely incomplete. We demonstrate that at the typical emission-line detection threshold of ~2 A in previous studies, most of the extranuclear wim emission in an ETG may evade detection, which could in turn cause ETGs to be classified as entirely gas-devoid systems.Conclusions. This study adds further observational evidence for a considerable heterogeneity among ETGs with regard to the physical properties and 2D kinematics of their extended wim component, and it clearly shows that a comprehensive understanding of these systems requires IFS studies over their entire optical extent.

DB-SMoT: A direction-based spatio-temporal clustering method

Abstract: Existing works for semantic trajectory data analysis have focused on the intersection of trajectories with application important geographic information and the use of the speed to find interesting places. In this paper we present a novel approach to find interesting places in trajectories, considering the variation of the direction as the main aspect. The proposed approach has been validated with real trajectory data associated to oceanic fishing vessels, with the objective to automatically find the real places where vessels develop fishing activities. Results have demonstrated that the method is very appropriate for applications in which the direction variation plays the essential role.

Decreased antioxidant defence in individuals infected by the human immunodeficiency virus.

Abstract: Background The oxidative stress associated with HIV infection may be important for the progression of the disease because reactive oxygen species activate the nuclear transcription factor NF-κB, which is obligatory for HIV replication. Patients and methods The activities of the antioxidant enzymes superoxide dismutase (SOD, EC 1.15.1.1) and glutathione peroxidase (GPx, EC 1.11.1.9) of blood plasma and peripheral blood mononuclear cells, as well as the plasma levels of ascorbate, α-tocopherol and β-carotene, were measured in 75 subjects with HIV infection and in 26 controls. The HIV-infected patients were classified according to the Walter Reed Army Institute criteria. Results The extracellular SOD (EC-SOD) of blood plasma activity was decreased in HIV-infected patients compared to controls, while the SOD activity of mononuclear cells decreased with the HIV-associated disease progression. GPx activities and α-tocopherol concentration of HIV-infected patients neither differed as compared to controls nor in relation to disease progression. Lower concentrations of ascorbate and β-carotene were found in HIV-infected patients than in controls. A positive correlation between CD4 lymphocyte counts and the SOD activities of plasma and mononuclear cells was found. Conclusion These results suggest that abnormalities of antioxidant defence, mainly of SOD activity, are related to the progression of the HIV infection.

In Vitro Oxygen-Glucose Deprivation to Study Ischemic Cell Death

Abstract: Oxygen-glucose deprivation (OGD ) is widely used as an in vitro model for stroke, showing similarities with the in vivo models of brain ischemia. In order to perform OGD, cell or tissue cultures, such as primary neurons or organotypic slices, and acutely prepared tissue slices are usually incubated in a glucose-free medium under a deoxygenated atmosphere, for example in a hypoxic chamber. Here, we describe the step-by-step procedure to expose cultures and acute slices to OGD, focusing on the most suitable methods for assessing cellular death and/or viability. OGD is a simple yet highly useful technique, not only for the elucidation of the role of key cellular and molecular mechanisms underlying brain ischemia, but also for the development of novel neuroprotective strategies.