Faint companions in the close environment of star-forming dwarf galaxies: possible overlooked starburst triggers?
Using the NASA Extragalactic Database, we have searched the close environment of 98 star– forming dwarf galaxies (SFDGs) from field– and low density environments for companion galaxies. Most of the found companions are dwarf galaxies, previously disregarded in environmental studies of SFDGs. Using a subsample at low redshifts, cz < 2000 kms 1 , i.e. less biased against dwarf companions, we find that 30% of the SFDGs have close companions within a projected ]
Chemical Evolution of Dwarf Irregular Galaxies - chemodynamical models and the effect of gas infall
Because of their low gravitational energies dwarf galaxies are greatly exposed to energetical influences by the interstellar medium, like e.g. stellar radiation, winds or explosions, or by their environment. While the metallicity depletion in dwarf galaxies can be explained in general by supernova-driven galactic winds, the reason for their low N/O ratios at low O abundance is not yet completely understood. Stellar yields enrich the different gas phases with elements that are characteristic for their stellar progenitors. Gas-phase transitions are necessary for a mixing of elements, but depend sensitively on the thermal and dynamical state of the interstellar medium. Models of chemical evolution start usually with a high N/O ratio at low O abundance according to a metal enrichment by ancient stellar populations with traditional yields, but can only reproduce the N/O-O peculiarity by the stepwise element release and mostly by the application of multiple starbursts in order to account also for a selective element reduction by galactic winds. Chemodynamical models of dwarf galaxies, however, demonstrate that strong evaporation of clouds by the hot supernova gas leads to an almost perfect mixing of the interstellar gas and a large-scale homogenization of abundance ratios. In addition, even with star-formation self-regulation these models can successfully account for the observed N/O-O values in a self-consistent way. Although new stellar yields have been taken into account which provide mainly secondary N production from massive stars, a significant discrepancy remains between the chemodynamical dwarf galaxy models and closed-box models that take the chemodynamical treatment into account. In this paper we therefore discuss to what amount gas infall is responsible to affect the N/O ratio.
Assessing the Competitiveness of the Philippine Auto Parts Industry
The development of the Philippine automotive parts and components sector is critical to the automotive assembly industry. The availability of competitive parts and components that are locally manufactured can significantly contribute to boost the competitiveness of the assembly sector. Given the current state of small and medium manufacturers, making them internationally competitive and linking them with regional production networks are major challenges. Less competitive firms will have to contend with reduced market shares and eventually bankruptcy. The few remaining competitive ones need to define their strategies and the market position that they want to pursue. The government has an important role to play in the firms adjustment process. While increasing economic integration represent market opportunities; penetrating the export market is not easy and does not come automatically. As the firms search for internal ways and exert effort to improve their competitiveness, this must be complemented with active government support.