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.

Procedimentos metodológicos na construção do conhecimento científico: a pesquisa bibliográfica

Abstract: This article concerns bibliographic research in the context of production of knowledge, as a methodological procedure that offers the researcher the possibility of seeking solutions to a research problem. It recognizes the need to present the scientific method chosen by the researcher; to present the forms of construction of the methodological design and the choice of procedures; and demonstrates how the presentation and analysis of the data obtained is configured. It also presents a methodological design of successive approximations, considering that the flexibility in the apprehension of data guarantees the dialectical movement in which the object of study can be constantly revised. That is, it postulates that bibliographic research involves conducting a tireless movement of apprehension of objectives, observance of steps, reading, questioning and critical interlocution with the bibliographic material and this demands epistemological vigilance.

Flavonoids: Prospective Drug Candidates

Abstract: The purpose of this review is to discuss the recent developments related to the chemistry and medicinal properties of flavonoids. Major flavonoids that show well categorized structures and well defined structure functionrelationships are: flavans, flavanones, flavones, flavanonols, flavonols, catechins, anthocyanidins and isoflavone. The biological properties of flavonoids include antioxidant, anti-inflamatory, antitumoral, antiviral and antibacterial, as well as a direct cytoprotective effect on coronary and vascular systems, the pancreas and the liver. These characteristics place them among the most attractive natural substances available to enrich the current therapy options.

Alternative diagnostic diagrams and the "forgotten" population of weak line galaxies in the SDSS

Abstract: A numerous population of weak line galaxies (WLGs) is often left out of statistical studies on emission line galaxies (ELGs) due to the absence of an adequate classification scheme, since classical diagnostic diagrams, like [OIII]/Hb vs [NII]/Ha (the BPT diagram), require the measurement of at least 4 emission lines. This paper aims to remedy this situation by transposing the usual divisory lines between Star Forming (SF) and AGN hosts, and between Seyferts and LINERs to diagrams that are more economical in terms of line quality requirements. By doing this, we rescue from the classification limbo a substantial number of sources and modify the global census of ELGs. More specifically: (1) We use the SDSS DR7 to constitute a suitable sample of 280k ELGs, 1/3 of which are WLGs. (2) Galaxies with strong emission lines are classified using the widely applied criteria of Kewley et al (2001), Kauffmann et al (2003), Stasinska et al (2006) and Kewley et al (2006). (3) We transpose these classification schemes to alternative diagrams keeping [NII]/Ha as a horizontal axis, but replacing Hb by a stronger line (Ha or [OII]), or substituting [OIII]/Hb ratio with the equivalent width of Ha. Optimized equations for the transposed divisory lines are provided. (4) We show that nothing significant is lost in the translation, but that the new diagrams allow one to classify up to 50% more ELGs. (5) Introducing WLGs in the census of galaxies in the local Universe increases the proportion of metal-rich SF galaxies and especially LINERs. (abridged)

Fundamentals of a new diode clamping multilevel inverter

Abstract: The conventional diode clamping inverter suffers from such problems as DC link unbalance, indirect clamping of the inner devices, turn-on snubbing of the inner DC rails as well as series association of the clamping diodes etc It is due largely to these problems that the application of the conventional diode clamping inverter in practice has been deterred, in spite of the growing discussion in the literature The paper proposes a new diode clamping inverter, which works without the series association of the clamping diodes An auxiliary resistive clamping network solving the indirect clamping problem of the inner devices is also discussed for both the new and conventional diode clamping inverter Operation principle, clamping mechanism, auxiliary clamping as well as experimentation are presented