Within the Herschel key project “The Warm And Dense ISM” (WADI) we systematically observea number of prominent photon-dominated regions (PDRs) to measure the impact of varying UVfields on the energy balance, the chemical and dynamical structure of heated molecularclouds.

The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) has recently conducted an extragalactic submillimetric survey of the Chandra Deep Field South region of unprecedented size, depth, and angular resolution in three wavebands centered at 250, 350, and 500 µm. BLAST wavelengths are chosen to study the Cosmic Infrared Background near its peak at 200 µm. We find that most of the CIB at these wavelengths is contributed by galaxies detected at 24 µm by the MIPS instrument on Spitzer, and that the source counts distribution shows a population with strongly evolving density and luminosity. These results anticipate what can be expected from the surveys that will be conducted with the SPIRE instrument on the Herschel space observatory.

Several of the current and next-generation cosmic microwave background(CMB) experiments have polarimetric capability, promising to add tothe finesse of precision cosmology. One of the contaminating Galacticforegrounds is thermal emission by dust. Since optical interstellarpolarization is commonly seen, from differential extinction by alignedaspherical dust particles, it is expected that thermal emission fromthese grains will be polarized. Indeed, in the Galactic plane and indark (molecular) clouds, dust emission in the infrared andsubmillimetre has been measured to be polarized. It seems likely thatthe faint diffuse cirrus emission, of more relevance to CMBexperiments, will be polarized too. We discuss how well the amount ofpolarization of this component can be predicted, making use of what isknown about optical (and infrared and ultraviolet) interstellarpolarization and extinction. Some constraints on the alignment of thecarrier of the dust-correlated anomalous microwave emission can bemade as well.

From our recent Faint Object Spectrograph (FOS) observations of the Orion Nebula obtained with the Hubble Space Telescope, we present preliminary results that address the nitrogen abundance. The list of detected lines and their identifications included the first measurement of the N II] 2142 Å line in an H II region. This measurement in conjunction with [O II] 2471 Å permits a new assessment of the important N/O ratio in Orion. Unfortunately, the measurements of the N III] 1747-54 Å multiplet and the O III] 1660-66 Å multiplet have poor signal-to-noise, precluding another independent derivation of N/O.