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FOLLOW-UP OBSERVATIONS TOWARD PLANCK COLD CLUMPS WITH GROUND-BASED RADIO TELESCOPES
LIU, TIE,WU, YUEFANG,MARDONES, DIEGO,KIM, KEE-TAE,MENTEN, KARL M.,TATEMATSU, KEN,CUNNINGHAM, MARIA,JUVELA, MIKA,ZHANG, QIZHOU,GOLDSMITH, PAUL F,LIU, SHENG-YUAN,ZHANG, HUA-WEI,MENG, FANYI,LI, DI,LO, NA The Korean Astronomical Society 2015 天文學論叢 Vol.30 No.2
The physical and chemical properties of prestellar cores, especially massive ones, are still far from being well understood due to the lack of a large sample. The low dust temperature (< 14 K) of Planck cold clumps makes them promising candidates for prestellar objects or for sources at the very initial stages of protostellar collapse. We have been conducting a series of observations toward Planck cold clumps (PCCs) with ground-based radio telescopes. In general, when compared with other star forming samples (e.g. infrared dark clouds), PCCs are more quiescent, suggesting that most of them may be in the earliest phase of star formation. However, some PCCs are associated with protostars and molecular outflows, indicating that not all PCCs are in a prestellar phase. We have identified hundreds of starless dense clumps from a mapping survey with the Purple Mountain Observatory (PMO) 13.7-m telescope. Follow-up observations suggest that these dense clumps are ideal targets to search for prestellar objects.
ALMA Reveals Sequential High-mass Star Formation in the G9.62+0.19 Complex
Liu, Tie,Lacy, John,Li, Pak Shing,Wang, Ke,Qin, Sheng-Li,Zhang, Qizhou,Kim, Kee-Tae,Garay, Guido,Wu, Yuefang,Mardones, Diego,Zhu, Qingfeng,Tatematsu, Ken’ichi,Hirota, Tomoya,Ren, Zhiyuan,Liu, Sheng-Yu American Astronomical Society 2017 The Astrophysical journal Vol.849 No.1
<P>Stellar feedback from high-mass stars (e.g., H II regions) can strongly influence the surrounding interstellar medium and regulate star formation. Our new ALMA observations reveal sequential high-mass star formation taking place within one subvirial filamentary clump (the G9.62 clump) in the G9.62+0.19 complex. The 12 dense cores (MM1-MM12) detected by ALMA are at very different evolutionary stages, from the starless core phase to the UC H II region phase. Three dense cores (MM6, MM7/G, MM8/F) are associated with outflows. The mass-velocity diagrams of the outflows associated with MM7/G and MM8/F can be well-fit by broken power laws. The mass-velocity diagram of the SiO outflow associated with MM8/F breaks much earlier than other outflow tracers (e.g., CO, SO, CS, HCN), suggesting that SiO traces newly shocked gas, while the other molecular lines (e.g., CO, SO, CS, HCN) mainly trace the ambient gas continuously entrained by outflow jets. Five cores (MM1, MM3, MM5, MM9, MM10) are massive starless core candidates whose masses are estimated to be larger than 25 M-circle dot, assuming a dust temperature of <= 20 K. The shocks from the expanding H II regions ('B' and 'C') to the west may have a great impact on the G9.62 clump by compressing it into a filament and inducing core collapse successively, leading to sequential star formation. Our findings suggest that stellar feedback from H II regions may enhance the star formation efficiency and suppress low-mass star formation in adjacent pre-existing massive clumps.</P>
Liu, Tie,Kim, Kee-Tae,Yoo, Hyunju,Liu, Sheng-yuan,Tatematsu, Ken’ichi,Qin, Sheng-Li,Zhang, Qizhou,Wu, Yuefang,Wang, Ke,Goldsmith, Paul F.,Juvela, Mika,Lee, Jeong-Eun,Tó,th, L. Viktor,Mardones, D American Astronomical Society 2016 The Astrophysical journal Vol.829 No.2
<P>We observed 146 Galactic clumps in HCN (4-3) and CS (7-6) with the Atacama Submillimeter Telescope Experiment 10 m telescope. A tight linear relationship between star formation rate and gas mass traced by dust continuum emission was found for both Galactic clumps and the high redshift (z > 1) star forming galaxies (SFGs), indicating a constant gas depletion time of similar to 100 Myr for molecular gas in both Galactic clumps and high z SFGs. However, low z galaxies do not follow this relation and seem to have a longer global gas depletion time. The correlations between total infrared luminosities (L-TIR) and molecular line luminosities (L-mol') of HCN (4-3) and CS (7-6) are tight and sublinear extending down to clumps with L-TIR similar to 10(3) L-circle dot. These correlations become linear when extended to external galaxies. A bimodal behavior in the L-TIR-L-mol' correlations was found for clumps with different dust temperature, luminosity-to-mass ratio, and sigma(line)/sigma(vir). Such bimodal behavior may be due to evolutionary effects. The slopes of L-TIR-L-mol' correlations become more shallow as clumps evolve. We compared our results with lower J transition lines in Wu et al. (2010). The correlations between clump masses and line luminosities are close to linear for low effective excitation density tracers but become sublinear for high effective excitation density tracers for clumps with L-TIR larger than L-TIR similar to 10(4.5) L-circle dot. High effective excitation density tracers cannot linearly trace the total clump masses, leading to a sublinear correlations for both M-clump-L-mol' and L-TIR-L-mol' relations.</P>
Global Income Inequality in Developing and Less Developed Countries
Paik, Won K.,Mardon, Russell Center for International Studies, Inha University 2003 Pacific Focus Vol.18 No.2
The purpose of this study is to analyze global income inequalities by examining n대-classical, dependency, and statist analyses. The present study utilizes both corss-sectional and longitudinal analyses for developing and less developed countries for the time frames of the 1970s and 1990s. The cross-sectional analyses tend to suggest that while the level of economic development partially affects income distribution, structural constraint of land tenure offers a greate explanation. The longitudinal analyses suggest that changes in income inequality are best explained by the nature and policies of the state in question.
JungHyeHwang,MoonIlPark,YounYoungHwang,HyungJinYoo,HelenJ.Mardon 생화학분자생물학회 2002 Experimental and molecular medicine Vol.34 No.3
Integrins are heterodimeric glycoproteins that havebeen found to undergo dynamic temporal and spa-tial changes in the endometrium during the men-strual cycle and in early pregnancy. Specificity ofintegrins is known to be different in human endome-trial stromal cells and decidual cells. These shifts ofintegrins suggested to play an important role inembryo implantation and can be modulated byprogesterone, cAMP derivatives, and cytokines. Themechanisms of decidualization and its precise phys-iological role are still not clearly understood and invitro systems could provide an alternative that over-comes limitations of studying such complex biolog-ical phenomena in vivo at the time of implantation.This study was undertaken to establish an in vitromodel system for human decidualization using 8-bromo-cAMP and to investigate the characteristicsof stromal integrin expression in vitro by 8-Br-cAMP.Endometrial stromal cells were isolated and cul-tured, and then were induced to decidualize by 0.5mM 8-Br-cAMP for 15 days. Immunofluorescencestaining and flow cytometric analyses of the integrinsubunits ( a1, a4, a5, a6, b1 and avb3) were per-formed at day 9. In the presence of 8-Br-cAMP, thestaining intensity of avb3 was significantly higherthan control and measurements for a1, a4, a5, a6,and b1 were similar. Immunofluorescent localizationof the integrins reflected the diferences obtainedfrom the flow cytometric analyses described above.In summary, the expresion of avb3 integrin increasedin stromal cells in vitro decidualized by 8-Br-cAMPand this up-regulation of avb3 integrin expressionduring decidualization might influence on humanimplantation.