Millimeter line observations toward four local galaxies

We present results of millimeter line observations toward four local gas-rich galaxies (NGC 3079, NGC 4258, NGC 6240 and VII Zw 31) with the IRAM 30 meter millimeter telescope. More than 33 lines in these four sources were detected, including normal dense gas tracers (HCN 1-0, HCO$^+$ 1-0, and C$_2$H 1-0, etc) and their isotopic species. H$^{13}$CN (1-0) and H$^{13}$CO$^+$ (1-0) are detected for the first time in NGC 4258. Optical depths of HCN 1-0 and HCO$^{+}$ 1-0 were estimated with detected isotopic lines in NGC 4258, which were 4.1 and 2.6, respectively. HC$_3$N $J=29-28$, which requires high volume density and high temperature to excite, was detected in NGC 6240. High ratios of HCO$^+$/HCN in NGC 4258 and NGC 6240 imply that this ratio might not be a perfect diagnostic tool between AGN and starburst environments, due to contamination/combination of both processes. The low HC$_3$N/HCN line ratios with less than 0.15 in NGC 4258, NGC 6240 and the non-detection of HC$_3$N line in NGC 3079 and VII Zw 31 indicates that these four galaxies are HC$_3$N-poor galaxies. The variation of fractional abundance of CN in different types of galaxies is large.Comment: 15pages, 13 figures; accepted for publication in MNRA

Distribution of HNCO 505−404_{05}-4_{04} in Massive Star-forming Regions

The goal of this paper is to study the spatial distribution of HNCO in massive star-forming regions, and investigate its spatial association with infrared sources, as well as physical conditions in region of HNCO emission. We have mapped nine massive star-forming regions in HNCO 5$_{05}-4_{04}$ with the Purple Mountain Observatory 13.7m telescope. The C18O maps of these sources were obtained simultaneously. The HNCO emission shows compact distribution, with emission peak centred on water masers. Nearly all the HNCO clumps show signs of embedded mid-infrared or far-infrared sources. The FWHM sizes of HNCO clumps are significantly smaller than C18O clumps but rather similar to HC3N clumps. We also found good correlation between the integrated intensities, linewidths and LSR velocities of HNCO and HC3N emission, implying similar excitation mechanism of these two species. As such, collisional excitation is likely to be the dominant excitation mechanism for HNCO 5$_{05}-4_{04}$ emission in galactic massive star-forming regions.Comment: 9 pages, 4 figures, accepted by A&

China’s perspective on similar biotherapeutic products

AbstractIn order to ensure most Chinese patients, particularly in the population with relatively low incomes, have access to safe, low cost, effective and quality-assured medicines, a number of “stand-alone” biological products, which have good quality, safety and efficacy have been marketed in China. Many countries and regions’ regulatory agencies are actively engaging in the development of bio-similar guidance and documents, which is being coordinated by WHO. As a major developing country of new drug development, China is now working hard to promote the process of new similar biotherapeutic products (SBPs) approval and also actively involved in developing and updating technical documents

The dependence of the IR-radio correlation on the metallicity

We have compiled a sample of 26 metal-poor galaxies with 12 + log(O/H) < 8.1 with both infrared continuum and 1.4 GHz radio continuum data. By comparing to galaxies at higher metallicity, we have investigated the dependence on the metallicity of the IR-radio relationship at 24 um, 70 um, 100 um and 160 um bands as well as the integrated FIR luminosity. It is found that metal-poor galaxies have on average lower qIR than metal-rich ones with larger offsets at longer IR wavelengths, from -0.06 dex in q24um to -0.6 dex in q160um. The qIR of all galaxies as a whole at 160 um show positive trends with the metallicity and IR-to-FUV ratio, and negative trends with the IR color, while those at lower IR wavelengths show weaker correlations. We proposed a mechanism that invokes combined effects of low obscured-SFR/total-SFR fraction and warm dust temperature at low metallicity to interpret the above behavior of qIR, with the former reducing the IR radiation and the latter further reducing the IR emission at longer IR wavelength. Other mechanisms that are related to the radio emission including the enhanced magnetic field strength and increased thermal radio contribution are unable to reconcile the IR-wavelength-dependent differences of qIR between metal-poor and metal- rich galaxies. In contrast to qIR, the mean total-SFR/radio ratio of metal-poor galaxies is the same as the metal-rich one, indicating the 1.4 GHz radio emission is still an effective tracer of SFRs at low metallicity.Comment: 25 pages, 11 figures, 4 tables. ApJ in pres

Large-Scale Spectroscopic Mapping of the ρ\rho Ophiuchi Molecular Cloud Complex I. The C2_{2}H to N2_2H+^+ Ratio as a Signpost of Cloud Characteristics

We present 2.5-square-degree C$_{2}$H N=1-0 and N$_2$H$^+$ J=1-0 maps of the $\rho$ Ophiuchi molecular cloud complex. These are the first large-scale maps of the $\rho$ Ophiuchi molecular cloud complex with these two tracers. The C$_{2}$H emission is spatially more extended than the N$_2$H$^+$ emission. One faint N$_2$H$^+$ clump Oph-M and one C$_{2}$H ring Oph-RingSW are identified for the first time. The observed C$_{2}$H to N$_{2}$H$^{+}$ abundance ratio ([C$_{2}$H]/[N$_{2}$H$^{+}$]) varies between 5 and 110. We modeled the C$_{2}$H and N$_2$H$^+$ abundances with 1-D chemical models which show a clear decline of [C$_2$H]/[N$_2$H$^+$] with chemical age. Such an evolutionary trend is little affected by temperatures when they are below 40 K. At high density (n$_H$ $>$ 10$^5$ cm$^{-3}$), however, the time it takes for the abundance ratio to drop at least one order of magnitude becomes less than the dynamical time (e.g., turbulence crossing time $\rm \sim$10$^5$ years). The observed [C$_2$H]/[N$_2$H$^+$] difference between L1688 and L1689 can be explained by L1688 having chemically younger gas in relatively less dense regions. The observed [C$_{2}$H]/[N$_{2}$H$^{+}$] values are the results of time evolution, accelerated at higher densities. For the relative low density regions in L1688 where only C$_2$H emission was detected, the gas should be chemically younger.Comment: Accepted by ApJ, 45 pages, 10 figure

Radar-based Hail-producing Storm Detection Using Positive Unlabeled Classification

Machine learning methods have been widely used in many fields of weather forecasting. However, some severe weather, such as hailstorm, is difficult to be completely and accurately recorded. These inaccurate data sets will affect the performance of machine-learning-based forecasting models. In this paper, a weather-radar-based hail-producing storm detection method is proposed. This method utilizes the bagging class-weighted support vector machine to learn from partly labeled hail case data and the other unlabeled data, with features extracted from radar and sounding data. The real case data from three radars of North China are used for evaluation. Results suggest that the proposed method could improve both the forecast accuracy and the forecast lead time comparing with the commonly used radar parameter methods. Besides, the proposed method works better than the method with the supervised learning model in any situation, especially when the number of positive samples contaminated in the unlabeled set is large