Molecular Gas and Star Formation in the Galactic Center Region The Galactic Center is obviously the most nearby core of a galaxy. We conducted a high-resolution, interferometric, wide-field survey of ammonia in this region with the Australia Telescope Compact Array. Due to its molecular structure, ammonia can be used as a thermometer and one of results comprise a temperature map of the dense molecular gas between Sgr A*, the black hole in the center of the Milky Way, and Sgr B2, one of the most prominent starbusts, at a resolution of ~1pc. our deep survey also lets us to derive the properties of thousands of individual molecular clouds. This provides comprehensive statistics of cloud sizes, densities, masses, temperatures, and pressures. In addition, the survey provides a high-resolution map of the continuum emission at 1.2cm wavelength. The Interstellar Medium in the Magellanic System The Magellanic Clouds are some of the most nearby galaxies. They are interacting dwarf galaxies and exhibit low-metallicities and a high radiation field - conditions which may resemble those of the distant Universe. We used both, the Mopra single dish telescope and the Australia Telescope Compact Array to study the star fromation conditions in these objects. Their proximity and their nearly face-on view allow us to distinguish between different molecular cloud and star forming scenarios. In addition, the properties of the dense gas can be determined and, hopefully, be used to better understand star formation at the very early stages of galaxy evolution. Molecular Gas and Star Formation in Starburst Galaxies and ULIRGS With the Australia Telescope Compact Array we observed a sample of the most prominent nearby southern starburst galaxies to detect the dense molecular gas. This particular gas phase is the material from which stars ultimately form. Despite the very strong ionizing radiation fields and the energetic impact of supernovae in starburst galaxies, i.e., galaxies with an extremely high current star formation rate, the galaxies still maintain their star formation activity over many tens or hundreds of Myr. It is therefore important to know why the molecular gas is not destroyed, how it can form in large quantities under such conditions, and why, eventually, starburst suddenly stop. In particular we observed lines of ammonia, which are used to probe the temperature of the dense gas. A second survey concentrates on the HCN/HNC ratio which is sensitive to the radiation field in these extremely starforming objects.  Triggering Star Formation and Stellar Feedback in Nearby Galaxies Star formation can have a dramatic impact on the surrounding interstellar medium. Young, massve stars are short-lived and dump massive amounts of mechanical energy into their surroundings in the form of strong stellar winds and supernova explosions. This influences the dynamics and energetics of the ISM and can be observed, e.g., in the form of expanding supergiant shells, observable in the 21cm line of neutral hydrogen (HI). This is of particular interest in dwarf galaxies, i.e., galaxies with a low gravitational potential. In fact, if the conditions are right, the energetic input of star formation can remove part or all of the ISM in a galaxy, which is an important factor for subsequent star formation and the metallicity enrichment of the intergalactic medium. With the Very Large Array (VLA), we will be observing a large sample of galaxies in a "Large Program" . This survey of ~70 galaxies is a complementary to the ANGST project, the goal of which is to determine the spatially resolved star formation history in a volume-limited sample of nearby galaxies with the Hubble Space Telescope (HST). The combination of HST and VLA will be essential to study the interplay of triggering of star formation and the stellar feedback of into the ISM. The data will eventually be complemented by observations of molecular gas with the Combined Array for Research  in Millimeter-wave Astronomy (CARMA). Hot Gas in Dwarf Starburst Galaxies As mentioned above, young massive stars dump massive amounts of energy into the surroundijng ISM. A direct consequence is the thermalization of this energy which heats up the gas to millions of degrees. This phase can be observed in X-ray emission. For my thesis, I studied X-ray Chandra data of a sample of nearby dwarf starburst galaxies. We determined the temperatures and the densities of this gas phase, its energetics and the possible removal of ISM caused by it. It turns out that a large envelope of less dense material may inhibit the total removal of gas, despite of the low gravitational potential of their host galaxies. We also address the metallicity distribution which arises from newly created elements in the supernovae, and compare the X-ray emission to shock tracers such as Halpha emission and to the cold atomica gas phase traced by HI. For one object, NGC3077, we were also able to derive and compare the properties of different hot gas filled bubbles in the same object. For more information, please have a look at my list of publications, and feel free to get in touch with me.