8,955 research outputs found

    Cardiac oxidative stress and inflammatory cytokines response after myocardial infarction

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    Oxidative stress in heart failure or during ischemia/reperfusion occurs as a result of the excessive generation or accumulation of free radicals or their oxidation products. Free radicals formed during oxidative stress can initiate lipid peroxidation, oxidize proteins to inactive states and cause DNA strand breaks. Oxidative stress is a condition in which oxidant metabolites exert toxic effects because of their increased production or an altered cellular mechanism of protection. In the early phase of acute heart ischemia cytokines have the feature to be functional pleiotropy and redundancy, moreover, several cytokines exert similar and overlapping actions on the same cell type and one cytokine shows a wide range of biological effects on various cell types. Activation of cytokine cascades in the infarcted myocardium was established in numerous studies. In experimental models of myocardial infarction, induction and release of the pro-inflammatory cytokines like TNF-&alpha (Tumor Necrosis Factor &alpha), IL-1&beta (Interleukin- 1&beta) and IL-6 (Interleukin-6) and chemokines are steadily described. The current review examines the role of oxidative stress and pro-inflammatory cytokines response following acute myocardial infarction and explores the inflammatory mechanisms of cardiac injur

    Dike propagation within active central volcanic edifices: constraints from Somma-Vesuvius, Etna and analogue models

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    Dikes within stratovolcanoes are commonly expected to have radial patterns. However, other patterns may also be also found, due to regional stresses, magmatic reservoirs, topographic variations. Here we investigate dike patterns within volcanic edifices, by studying dike and fissure complexes at Somma-Vesuvius and Etna (Italy) and using analogue models. At the surface, the dikes and fissures show a radial configuration. At depths of tens to several hundreds of m, in areas exposed by erosion, tangential and oblique dikes are also present. Analogue models indicate that dikes approaching the flanks of cones, regardless of their initial orientation, reorient to become radial (parallel to the maximum gravitational stress). This reorientation is a significant process in shallow magma migration and may also control the emplacement of dike-fed fissures reaching the lower slopes of the volcano

    Ranking Australian Economics Departments by Research Productivity

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    This study ranks Australian economics departments according to their average research productivity during 1998-2002. The highest ranked departments are those at ANU, JCU, Melbourne, Tasmania and UWA. We also rank departments according to the variability of research productivity among their members, the assumption being that, other things being equal, the less variable is productivity within a department, the better. Research productivity is found to be highly skewed within all departments. However, in general, research productivity is more (less) evenly distributed within those departments that have relatively high (low) average research productivity

    Trade reforms and breakpoints in Australia\u27s manufactured trade: an application of the Zivot and Andrews model

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    Trade liberalization is expected to increase imports but also exports via reduced input costs and increased domestic competition. This paper investigates whether this is the case for Australian manufactured goods. We begin by briefly describing the trends in the effective rate of protection, imports and exports in Australia over the last 30 years and then investigate the existence of major structural breaks in the imports and exports series by applying the Zivot and Andrews (1992 )test, using annual time series data from 1968/69 to 2003/2004. We find that a significant structural break occurred for imports in 1988/1989, which coincides with the introduction of major trade liberalization policy. We also find a significant structural break for exports with the three-year lag in 1992/1993

    Dyke Emplacement and Hazard at Stromboli

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    In February 2007, two effusive vents opened along the flank of Sciara del Fuoco (SdF) depression at Stromboli. The summit craters collapsed, obstructing the central conduit, choking the vents and increasing the deformation within SdF. Here a new vent opened, releasing the excess magmatic pressure. The eruption continued, after a summit explosion, until April. The vents were fed by laterally propagating dykes. Vent location is similar to that of the 2002-2003 eruption, fed by dykes triggering landslides, which in turn produced a tsunami. However, the 2007 eruption did not develop landslides, suggesting that their triggering also depends on other factors, (i.e. magmatic pressure)

    ALMA observations of the Red Rectangle, a preliminary analysis

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    We aim to study equatorial disks in rotation and axial outflows in post-AGB objects, as to disclose the formation and shaping mechanisms in planetary nebulae. So far, both disks and outflows had not been observed simultaneously. We have obtained high-quality ALMA observations of 12CO and 13CO J=3-2 and 12CO J=6-5 line emission in the Red Rectangle, the only post-AGB/protoplanetary object in which a disk in rotation has been mapped up to date. These observations provide an unprecedented description of the complex structure of this source. Together with an equatorial disk in rotation, we find a low-velocity outflow that occupies more or less the region placed between the disk and the optical X-shaped nebula. From our observations and preliminary modeling of the data, we confirm the previously known properties of the disk and obtain a first description of the structure, dynamics, and physical conditions of the outflow.Comment: 5 pages, 5 figure

    Observational evidence of the formation of cyanopolyynes in CRL618 through the polimerization of HCN

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    The abundance ratio of consecutive members of the cyanopolyynes family has been explored in CRL618 using data acquired in a complete line survey covering the frequency range 81-356 GHz. The Jup range explored for the different molecules is the following: 1 to 4 for HCN and HNC, 9 to 39 for HC3N, 31 to 133 for HC5N, and 72 to 85 for HC7N (not detected beyond Jup=85). The lowest vibrationally excited state of HC7N (nu_15 at 62 cm^-1) has been tentatively detected. Data analysis has been performed by extending our previous geometrical and radiative transfer model of the slowly expanding envelope (SEE) surrounding the compact central continuum source of CRL 618, that was established from the study of rotational lines in several vibrationally excited states of HC_3N. The new lines analyzed here require to model the high velocity wind (HVW) component and the colder circumstellar gas, remnant of the AGB phase of CRL618. The derived HC3N/HC5N and HC5N/HC7N abundance ratios from this set of uniformly calibrated lines are between 3 and 6 in the different regions, similar to standard values in the CSM and ISM, and consistent with previous estimates obtained from ISO observations and chemical models. However, the abundance ratios of HC3N, HC5N and HC7N with respect to HCN are at least two orders of magnitude larger than those typical for AGB C-rich stars, such as IRC+10216. This fact indicates that, in the short transition toward the Planetary Nebula phase, HCN is quickly reprocessed into longer cyanopolyyne chains. A similar behavior was previously found in this object for the polyacetylenic chains (C(2n)H2).Comment: 8 figures, accepted in ApJ main journa
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