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We studied the brightness and spectral evolution of the young eruptive star V1647 Ori during its recent outburst in the period 2004 FebruaryY2006 September. We performed a photometric follow-up in the bands V, R C , I C , J, H, and K s , as well as visible and near-IR spectroscopy. The main results derived from combining our data with those published by other authors are as follows: the brightness of V1647 Ori stayed more than 4 mag above the preoutburst level until 2005 October, when it started a rapid fading. In the high state we found a periodic component in the optical light curves with a period of 56 days. The delay between variations of the star and variations in the brightness of clumps of nearby nebulosity corresponds to an angle of 61 AE 14 between the axis of the nebula and the line of sight. The overall appearance of the infrared and optical spectra did not change in the period 2004 MarchY2005 March, although a steady decrease of H i emission-line fluxes could be observed. In 2006 May, in the quiescent phase, the He i 1.083 m line was observed in emission, contrary to its deep blueshifted absorption observed during the outburst. The J À H and H À K s color maps of the infrared nebula reveal an envelope around the star whose largest extension is about 18 00 (0.03 pc). The color distribution of the infrared nebula suggests reddening of the scattered light inside a thick circumstellar disk. Comparison of the K s and H images of McNeil's Nebula, the conical nebulosity illuminated by V1647 Ori, shows that HH 22A, the Spitzer infrared source, and the bright clump C of the nebula may be unrelated objects. We show that the observed properties of V1647 Ori could be interpreted in the framework of the thermal instability models of Bell and coworkers. V1647 Ori might belong to a new class of young eruptive stars, defined by relatively short timescales, recurrent outbursts, a modest increase in bolometric luminosity and accretion rate, and an evolutionary state earlier than that of typical EXors.

In serum-starved NIH 3T3 clone 7 fibroblasts, choline phosphate (ChoP) (0.5-1 mM) and insulin synergistically stimulate DNA synthesis. Here we report that ATP also greatly enhanced the mitogenic effects of ChoP (0.1-1 mM) both in the absence and presence of insulin; maximal potentiating effects required 50 -100 M ATP. The co-mitogenic effects of ATP were mimicked by adenosine 5-O-(3-thiotriphosphate), adenosine 5-O-(2-thiodiphosphate), ADP, and UTP, but not by AMP or adenosine, indicating the mediatory role of a purinergic P 2 receptor. Externally added ChoP acted on DNA synthesis without its detectable uptake into fibroblasts, indicating that ChoP can be a mitogen only if it is released from cells. Extracellular ATP (10 -100 M) induced extensive release of ChoP from fibroblasts. ChoP had negligible effects, even in the presence of ATP or insulin, on the activity state of p42/p44 mitogen-activated protein kinases, while in combination these agents stimulated the activity of phosphatidylinositol 3-kinase (PI 3-kinase). Expression of a dominant negative mutant of the p85 subunit of PI 3-kinase or treatments with the PI 3-kinase inhibitor wortmannin only partially (ϳ40 -50%) reduced the combined effects of ChoP, ATP, and insulin on DNA synthesis; in contrast, the pp70 S6 kinase inhibitor rapamycin almost completely inhibited these effects. ATP and insulin also potentiated, while rapamycin strongly inhibited, the mitogenic effects of sphingosine 1-phosphate (S1P). Furthermore, even maximally effective concentrations of ChoP and S1P synergistically stimulated DNA synthesis. The results indicate that in the presence of extracellular ATP and/or S1P, ChoP induces mitogenesis through an extracellular site by mechanisms involving the activation of pp70 S6 kinase and, to a lesser extent, PI 3-kinase.

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Aims. An all-sky survey of loop-and arc-like intensity enhancements has been performed to investigate the large-scale structure of the diffuse far-infrared emission. Methods. We used maps made of 60 and 100 µm processed IRAS data (Sky Survey Atlas and dust infrared emission maps) to identify large-scale structures: loops, arcs, or cavities, in the far-infrared emission in the Galaxy. Distances were attributed to a subsample of loops using associated objects. Results. We identified 462 far-infrared loops, analysed their individual FIR properties and their distribution. This data forms the Catalogue of Far-Infrared Loops in the Galaxy. We obtained observational estimates of f in ≈ 30% and f out ≈ 5% for the hot gas volume filling factor of the inward and outward Galactic neighbourhood of the Solar System. We obtained a slope of the power-law size luminosity function β = 1.37 for low Galactic latitudes in the outer Milky Way. Conclusions. Deviations in the celestial distribution of far-infrared loops clearly indicate that violent events frequently overwrite the structure of the interstellar matter in the inner Galaxy. Our objects trace out the spiral arm structure of the Galaxy in the neighbourhood of the Sun and their distribution clearly suggests that there is an efficient process that can generate loop-like features at high Galactic latitudes. Power-law indices of size luminosity distributions suggest that the structure of the ISM is ruled by supernovae and stellar winds at low Galactic latitudes, while it is governed by supersonic turbulence above the Galactic plane.

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The applicability of friction stir welding has been studied on polypropylene sheets. The joint strength has been analysed in terms of rotation and translation speed. It has been demonstrated that in addition to the judicious selection of welding parameters the proper construction of the welding tool is also very important. The crystallinity of the seam and its neighbourhood has been analysed by DSC, the structure of the seam border region has been analysed by optical and by scanning electron microscopy. It was found, that the seam has undergone embrittlement, as a result of non-satisfactory homogenization. Having analysed the flow circumstances during welding on seams produced by proper tool geometries it has been demonstrated that homogenization and, consequently the joint strength can be substantially improved.

The phospholipase D (PLD)-mediated synthesis of phosphatidylethanol (PtdEtOH) and the hydrolysis of phosphatidylethanolamine (PtdEtn) and phosphatidylcholine (PtdCho) were examined in drug-sensitive and multidrug-resistant lines of MCF-7 human breast carcinoma cells. In drug-sensitive (MCF-7/WT) cells, the protein kinase C (PKC) activator phorbol 12-myristate 13-acetate (PMA) failed to enhance either the synthesis of PtdEtOH or the hydrolysis of either phospholipid. In the drug-resistant (MCF-7/MDR) cells, 100 nM PMA greatly enhanced both the synthesis of PtdEtOH (approximately 21-fold) and the hydrolysis of PtdEtn (approximately 29-fold), but had no effect on the hydrolysis of PtdCho. The PLD activators sphingosine and H2O2 were found to elicit only a slight (1.28-1.4-fold) stimulatory effect on PtdCho hydrolysis in both the MCF-7/WT and MCF-7/MDR cell types, and had only a small effect on PtdEtn hydrolysis in the MCF-7/WT cells as well. However, these agents significantly (approximately 2.6-3.5-fold) stimulated PtdEtn hydrolysis in the MCF-7/MDR cells. These data indicate that MCF-7/MDR cells contain a PtdEtn-specific PLD activity which can be selectively stimulated by PMA, sphingosine and H2O2.