Infrared Studies of Molecular Shocks in the Supernova Remnant HB21: I. Thermal Admixture of Shocked H_2 Gas in the North

We present near- and mid-infrared observations on the shock-cloud interaction region in the northern part of the supernova remnant HB21, performed with the InfraRed Camera (IRC) aboard AKARI satellite and the Wide InfraRed Camera (WIRC) at the Palomar 5 m telescope. The IRC 7 um (S7), 11 um (S11), and 15 um (L15) band images and the WIRC H2 v = 1 -> 0 S(1) 2.12 um image show similar shock-cloud interaction features. We chose three representative regions, and analyzed their IRC emissions through comparison with H2 line emissions of several shock models. The IRC colors are well explained by the thermal admixture model of H2 gas--whose infinitesimal H2 column density has a power-law relation with the temperature T, dN ~ T^-b dT--with n(H2) ~ 10^3 cm^-3, b ~ 3, and N(H2 ;T > 100K) ~ 3x10^20 cm^-2. The derived b value may be understood by a bow shock picture, whose shape is cycloidal (cuspy) rather than paraboloidal. However, this picture raises another issue that the bow shocks must reside within ~0.01 pc size-scale, smaller than the theoretically expected. Instead, we conjectured a shocked clumpy interstellar medium picture, which may avoid the sizescale issue while explaining the similar model parameters. The observed H2 v = 1 -> 0 S(1) intensities are a factor of ~17 - 33 greater than the prediction from the power-law admixture model. This excess may be attributed to either an extra component of hot H2 gas or to the effects of collisions with hydrogen atoms, omitted in our power-law admixture model, both of which would increase the population in the v = 1 level of H2.Comment: 14 pages, 9 figures, ApJ accepted, higher resolution @ http://astro.snu.ac.kr/~jhshinn/ms.pd

Ortho-to-Para Ratio Studies of Shocked H2 Gas in the Two Supernova Remnants IC 443 and HB 21

We present near-infrared (2.5-5.0 {\mu}m) spectral studies of shocked H2 gas in the two supernova remnants IC 443 and HB 21, which are well known for their interactions with nearby molecular clouds. The observations were performed with Infrared Camera (IRC) aboard the AKARI satellite. At the energy range 7000 K <= E(v,J) <= 20000 K, the shocked H2 gas in IC 443 shows an ortho-to-para ratio (OPR) of 2.4+0.3-0.2, which is significantly lower than the equilibrium value 3, suggesting the existence of non-equilibrium OPR. The shocked gas in HB 21 also indicates a potential non-equilibrium OPR in the range of 1.8-2.0. The level populations are well described by the power-law thermal admixture model with a single OPR, where the temperature integration range is 1000-4000 K. We conclude that the obtained non-equilibrium OPR probably originates from the reformed H2 gas of dissociative J-shocks, considering several factors such as the shock combination requirement, the line ratios, and the possibility that H2 gas can form on grains with a non-equilibrium OPR. We also investigate C-shocks and partially-dissociative J-shocks for the origin of the non-equilibrium OPR. However, we find that they are incompatible with the observed ionic emission lines for which dissociative J-shocks are required to explain. The difference in the collision energy of H atoms on grain surfaces would make the observed difference between the OPRs of IC 443 and HB 21, if dissociative J-shocks are responsible for the H2 emission. Our study suggests that dissociative J-shocks can make shocked H2 gas with a non-equilibrium OPR.Comment: aastex preprint 12pt, 32 pages, 9 figures, 7 tables, ApJ accepte

Infrared Studies of Molecular Shocks in the Supernova Remnant HB 21: II. Thermal Admixture of Shocked H2_2 Gas in the South

We present near- and mid-infrared observations on the shock-cloud interaction region in the southern part of the supernova remnant HB 21, performed with the InfraRed Camera (IRC) aboard AKARI satellite and the Wide InfraRed Camera (WIRC) at the Palomar 5 m telescope. The IRC 4 um (N4), 7 um (S7), and 11 um (S11) band images and the WIRC H2 v=1->0 S(1) 2.12 um image show similar diffuse features, around a shocked CO cloud. We analyzed the emission through comparison with the H2 line emission of several shock models. The IRC colors are well explained by the thermal admixture model of H2 gas--whose infinitesimal H2 column density has a power-law relation with the temperature $T$, $dN\sim T^{-b}dT$--with n(H2) $\sim3.9\times10^4$ cm^{-2}, $b\sim4.2$, and N(H2;T>100K) $\sim2.8\times10^{21}$ cm^{-2}. We interpreted these parameters with several different pictures of the shock-cloud interactions--multiple planar C-shocks, bow shocks, and shocked clumps--and discuss their weaknesses and strengths. The observed H2 v=1->0 S(1) intensity is four times greater than the prediction from the power-law admixture model, the same tendency as found in the northern part of HB 21 (Paper I). We also explored the limitation of the thermal admixture model with respect to the derived model parameters.Comment: 35 pages, 10 figures, Accepted in "Advances in Space Research", higher resolution @ http://astro.snu.ac.kr/~jhshinn/asr-20090921-submitted_arxiv.pdf ; rev.2 - deletion of section 6.4 and the related content

Syk/Src Pathway-Targeted Inhibition of Skin Inflammatory Responses by Carnosic Acid

Carnosic acid (CA) is a diterpene compound exhibiting antioxidative, anticancer, anti-angiogenic, anti-inflammatory, anti-metabolic disorder, and hepatoprotective and neuroprotective activities. In this study, the effect of CA on various skin inflammatory responses and its inhibitory mechanism were examined. CA strongly suppressed the production of IL-6, IL-8, and MCP-1 from keratinocyte HaCaT cells stimulated with sodium lauryl sulfate (SLS) and retinoic acid (RA). In addition, CA blocked the release of nitric oxide (NO), tumor necrosis factor (TNF)-α, and prostaglandin E2 (PGE2) from RAW264.7 cells activated by the toll-like receptor (TLR)-2 ligands, Gram-positive bacterium-derived peptidoglycan (PGN) and pam3CSK, and the TLR4 ligand, Gram-negative bacterium-derived lipopolysaccharide (LPS). CA arrested the growth of dermatitis-inducing Gram-positive and Gram-negative microorganisms such Propionibacterium acnes, Pseudomonas aeruginosa, and Staphylococcus aureus. CA also blocked the nuclear translocation of nuclear factor (NF)-κB and its upstream signaling including Syk/Src, phosphoinositide 3-kinase (PI3K), Akt, inhibitor of κBα (IκBα) kinase (IKK), and IκBα for NF-κB activation. Kinase assays revealed that Syk could be direct enzymatic target of CA in its anti-inflammatory action. Therefore, our data strongly suggest the potential of CA as an anti-inflammatory drug against skin inflammatory responses with Src/NF-κB inhibitory properties

AKARI Infrared Observations of the Supernova Remnant G292.0+1.8: Unveiling Circumstellar Medium and Supernova Ejecta

We present the results of AKARI observations of the O-rich supernova remnant G292.0+1.8 using six IRC and four FIS bands covering 2.7-26.5 um and 50-180 um, respectively. The AKARI images show two prominent structures; a bright equatorial ring structure and an outer elliptical shell structure. The equatorial ring structure is clumpy and incomplete with its western end opened. The outer shell is almost complete and slightly squeezed along the north-south direction. The central position of the outer shell is ~ 1' northwest from the embedded pulsar and coincides with the center of the equatorial ring structure. The equatorial ring and the elliptical shell structures were partly visible in optical and/or X-rays, but they are much more clearly revealed in our AKARI images. There is no evident difference in infrared colors of the two prominent structures, which is consistent with the previous proposition that both structures are of circumstellar origin. However, we have detected faint infrared emission of a considerably high 15 to 24 um ratio associated with the supernova ejecta in the southeastern and northwestern areas. Our IRC spectra show that the high ratio is at least partly due to the emission lines from Ne ions in the supernova ejecta material. In addition we detect a narrow, elongated feature outside the SNR shell. We derive the physical parameters of the infrared-emitting dust grains in the shocked circumstellar medium and compare the result with model calculations of dust destruction by a SN shock. The AKARI results suggest that the progenitor was at the center of the infrared circumstellar shell in red supergiant stage and that the observed asymmetry in the SN ejecta could be a result of either a dense circumstellar medium in the equatorial plane and/or an asymmetric explosion.Comment: 24 pages, 8 figures, 6 tables; Accepted for publication in Ap

Far-Infrared Luminous Supernova Remnant Kes 17

We present the results of infrared (IR; 2.5--160 um) observations of the supernova remnant (SNR) Kes 17 based on the data obtained with the AKARI and Spitzer satellites. We first detect bright continuum emission of its western shell in the mid- and far-IR wavebands together with its near-IR molecular line emission. We also detect hidden mid-IR emission of its southern shell after subtraction of the background emission in this region. The far-IR luminosity of the western shell is ~ 8100 L_sun, which makes Kes 17 one of the few SNRs of significant far-IR emission. The fittings of the spectral energy distribution indicate the existence of two dust components: ~ 79 K (hot) and ~ 27 K (cold) corresponding to the dust mass of ~ 6.2x10^{-4} M_sun and ~ 6.7 M_sun, respectively. We suggest that the hot component represents the dust emission of the material swept up by the SNR to its western and southern boundaries, compatible with the distribution of radio continuum emission overlapping the mid-IR emission in the western and southern shells. The existence of hot (~ 2,000 K), shocked dense molecular gas revealed by the near-IR molecular line emission in the western shell, on the other hand, suggests that the cold dust component represents the dust emission related to the interaction between the SNR and nearby molecular gas. The excitation conditions of the molecular gas appear to be consistent with those from shocked, clumpy admixture gas of different temperatures. We discuss three possibilities for the origin of the bright far-IR emission of the cold dust in the western shell: the emission of dust in the inter-clump medium of shocked molecular clouds, the emission of dust in evaporating flows of molecular clouds engulfed by hot gas, and the emission of dust of nearby molecular clouds illuminated by radiative shocks.Comment: 14 pages including 6 figures, accepted for publication in Ap

Epidemiologic survey of head and neck cancers in Korea.

Head and neck cancers have never been systematically studied for clinical purposes yet in Korea. This epidemiological survey on head and neck cancer patients was undertaken from January to December 2001 in 79 otorhinolaryngology resident-training hospitals nationwide. The number of head and neck cancer patients was 1,063 cases in the year. The largest proportion of cases arose in the larynx, as many as 488 cases, which accounted for 45.9%. It was followed by, in order of frequency, oral cavity (16.5%), oropharynx (10.0%), and hypopharynx (9.5%). The male:female ratio was 5:1, and the mean age was 60.3 yr. Surgery was the predominant treatment modality in head and neck cancers: 204 (21.5%) cases were treated with only surgery, 198 (20.8%) cases were treated with surgery and radiotherapy, 207 cases (21.8%) were treated with combined therapy of surgery, radiotherapy, and chemotherapy. Larynx and hypopharynx cancers had a stronger relationship with smoking and alcohol drinking than other primary site cancers. Of them, 21 cases were found to be metastasized at the time of diagnosis into the lung, gastrointestinal tract, bone, or brain. Coexisting second primary malignancies were found in 23 cases. At the time of diagnosis, a total of 354 cases had cervical lymph node metastasis accounting for 42.0%