tokens: The authors thank Dr. J.J. Tobin for providing the CARMA N 2 H + (1–0) data for Figure 1 . We are grateful to Dr. A. Palau for providing the data points in Figure 13 . We thank Dr. T. Stanke for providing us with the JCMT CO (3–2) data for comparison. The authors acknowledge the staff at APEX, IRAM 30 m, SMA, and JVLA for assistance with operations. The Submillimeter Array is a joint project between the Smithsonian Astrophysical Observatory and the Academia Sinica Institute of Astronomy and Astrophysics and is funded by the Smithsonian Institution and the Academia Sinica. T.H.H. and S.P.L. are thankful for the support of the Ministry of Science and Technology (MoST) of Taiwan through grants NSC 98-2112- M-007-007-MY3, NSC 101-2119-M-007-004, MoST 102-2119-M-007-004-MY3, and MoST 104-2119-M-007-021. T.H.H. appreciates the grant from MOST with the PhD exchange student award (MOST 103-2917-I-007-005) and also thanks the MPIfR for supporting him as a visiting astronomer in Bonn, Germany.
ner_tags: O O O B-Person I-Person I-Person O O O B-Wavelength B-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength O O O O O O O O B-Person I-Person I-Person O O O O O O O O O O O B-Person I-Person I-Person O O O O O B-Telescope B-Wavelength I-Wavelength O O O O O O O O O B-Telescope B-Telescope I-Telescope I-Telescope B-Telescope O B-Telescope O O O O O B-Telescope I-Telescope O O O O O O B-Observatory I-Observatory I-Observatory O O B-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization O O O O O B-Organization I-Organization O O B-Organization I-Organization B-Person O B-Person O O O O O O O B-Organization I-Organization I-Organization I-Organization I-Organization B-Organization O B-Location O O B-Organization B-Grant I-Grant B-Organization B-Grant B-Organization B-Grant O B-Organization B-Grant B-Person O O O O B-Organization O O B-Fellowship I-Fellowship I-Fellowship I-Fellowship B-Organization B-Fellowship O O O O B-Organization O O O O O O O O B-Location I-Location