Dense gas in nearby galaxies: XV. Hot ammonia in NGC253, Maffei2 and IC342

The detection of NH3 inversion lines up to the (J,K)=(6,6) level is reported toward the central regions of the nearby galaxies NGC253, Maffei2, and IC342. The observed lines are up to 406K (for (J,K)=(6,6)) and 848K (for the (9,9) transition) above the ground state and reveal a warm (T_kin= 100 - 140 K) molecular component toward all galaxies studied. The tentatively detected (J,K)=(9,9) line is evidence for an even warmer (>400K) component toward IC342. Toward NGC253, IC342 and Maffei2 the global beam averaged NH3 abundances are 1-2 10^-8, while the abundance relative to warm H2 is around 10^-7. The temperatures and NH3 abundances are similar to values found for the Galactic central region. C-shocks produced in cloud-cloud collisions can explain kinetic temperatures and chemical abundances. In the central region of M82, however, the NH3 emitting gas component is comparatively cool (~ 30K). It must be dense (to provide sufficient NH3 excitation) and well shielded from dissociating photons and comprises only a small fraction of the molecular gas mass in M82. An important molecular component, which is warm and tenuous and characterized by a low ammonia abundance, can be seen mainly in CO. Photon dominated regions (PDRs) can explain both the high fraction of warm H_2 in M82 and the observed chemical abundances.Comment: 11 pages, 3 Figures, 5 Table

Mass Spectrometric Measurement of Martian Krypton and Xenon Isotopic Abundance

The Viking gas chromatograph mass spectrometer experiment provided significant data on the atmospheric composition at the surface of Mars, including measurements of several isotope ratios. However, the limited dynamic range of this mass spectrometer resulted in marginal measurements for the important Kr and Xe isotopic abundance. The Xe-129 to Xe-132 ratio was measured with an uncertainty of 70%, but none of the other isotope ratios for these species were obtained. Accurate measurement of the Xe and Kr isotopic abundance in this atmosphere provides an important data point in testing theories of planetary formation and atmospheric evolution. The measurement is also essential for a stringent test for the Martian origin of the SNC meteorites, since the Kr and Xe fractionation pattern seen in gas trapped in glassy nodules of an SNC (EETA 79001) is unlike any other known solar system resevoir. Current flight mass spectrometer designs combined with the new technology of a high-performance vacuum pumping system show promise for a substantial increase in gas throughput and the dynamic range required to accurately measure these trace species. Various aspects of this new technology are discussed

CS in nearby galaxies: Distribution, kinematics, and multilevel studies

As a result of observations at the Institute for Radio Astronomy in the Millimeter Range (IRAM) 30-m telescope, maps of the distribution of the J = 2-1 transition of CS toward the galaxies IC 342 and NGC 253 are presented. The distribution of the CS emission from NGC 253 is consistent with the CO 1-0 line. The distribution of the CS emission from IC 342, however, resembles more that seen in the CO 3-2 line. For the first time, the detection of the isotopic substitution C-34S is reported toward an external galaxy: The C-34S 2-1 line has been detected toward NGC 253 and M 82 and the C-34S line has been detected tentatively toward M 82. Also for the first time, extragalactic CS has been observed in the 3-2 (toward NGC 253, IC 342 and M 82) and 5-4 (NGC 253 and IC 342) transitions

Methanol detection in M82

We present a multilevel study of the emission of methanol, detected for the first time in this galaxy, and discuss the origin of its emission. The high observed methanol abundance of a few 10^-9 can only be explained if injection of methanol from dust grains is taken into account. While the overall [CH3OH]/[NH3] ratio is much larger than observed towards other starbursts, the dense high excitation component shows a similar value to that found in NGC 253 and Maffei 2. Our observations suggest the molecular material in M 82 to be formed by dense warm cores, shielded from the UV radiation and similar to the molecular clouds in other starbursts, surrounded by a less dense photodissociated halo. The dense warm cores are likely the location of recent and future star formation within M 82.Comment: Accepted for publication in A&A Letter

Aims and Examples of Water Quality Modeling in the G.D.R

In the German Democratic Republic, the annually available mean recovered water resource per inhabitant is significantly less than in other European states. Approximately half of this quantity is actually available for utilization. Thus, the natural yield of water is very limited and an extensive expansion of water supply is impossible. About 75% is taken from surface waters and 25% from ground water. During dry months the multiple use of water increases to a factor of 3 to 4 in areas where industry and population agglomerate. The growing demand for water by population, agriculture and industry can be met only by an intensification of the utilization of water resources. But we cannot hope to manage water resources in a rational way unless we understand the relationships between the amount of water used by man, the input from man into ground and surface water and the resulting ecosystem response, especially the resulting water quality of rivers, lakes, reservoirs and aquifers

The role of community radio and recent reforms to democratize media markets in Uruguay, Argentina, and Chile

The media sector is vital to the quality of democracies, yet its products or services are often traded in commercial markets. In Latin America, media markets are usually dominated by only a few large commercial media companies. Regulation often dates back to the times of military dictatorships, while neoliberal reforms have later accelerated concentration tendencies and increased the emphasis on commercial logics. The current state of the media sector is increasingly criticized as posing severe limits to processes of democratic deliberation, illegitimately concentrating political power and complementing other forms of social exclusion. In the last few years, calls for democratizing media markets have been echoed in some countries by policy reforms in the broadcasting sector. This paper sketches the regulatory challenge of democratizing predominantly commercial and concentrated broadcasting markets in Latin America. I demonstrate that commercial diversification is a necessary but not sufficient condition for plural media markets. Furthermore, debates about democratization go beyond the commercial diversity of media channels and rather address the conditions of access to the public sphere. Against the background of recent legislation in Uruguay, Argentina and Chile, I identify a trend toward the promotion of non-commercial broadcasters. Although media regulation is partly modernized to account for democratic demands, the extent of the reforms differs greatly. As the democratization of concentrated media markets conflicts with the interests of commercial firms, such reforms are only to be expected where active social movements push for changes