Carbon Recombination Lines toward the Riegel-Crutcher Cloud and other Cold HI Regions in the inner Galaxy

We report here, for the first time, the association of low frequency CRRL with \HI\ self-absorbing clouds in the inner Galaxy and that the CRRLs from the innermost $\sim 10^{\circ}$ of the Galaxy arise in the Riegel-Crutcher (R-C) cloud. The R-C cloud is amongst the most well known of \HI\ self-absorbing (HISA) regions located at a distance of about 125 pc in the Galactic centre direction. Taking the R-C cloud as an example, we demonstrate that the physical properties of the HISA can be constrained by combining multi-frequency CRRL and \HI\ observations. The derived physical properties of the HISA cloud are used to determine the cooling and heating rates. The dominant cooling process is emission of the \CII\ 158 \mum line whereas dominant heating process in the cloud interior is photoelectric emission. Constraints on the FUV flux (G0 $\sim$ 4 to 7) falling on the R-C cloud are obtained by assuming thermal balance between the dominant heating and cooling processes. The H$_2$ formation rate per unit volume in the cloud interior is $\sim$ 10$^{-10}$ -- 10$^{-12}$ s$^{-1}$ \cmthree, which far exceeds the H$_2$ dissociation rate per unit volume. We conclude that the self-absorbing cold \HI\ gas in the R-C cloud may be in the process of converting to the molecular form. The cold \HI\ gas observed as HISA features are ubiquitous in the inner Galaxy and form an important part of the ISM. Our analysis shows that combining CRRL and \HI\ data can give important insight into the nature of these cold gas. We also estimate the integration times required to image the CRRL forming region with the upcoming SKA pathfinders. Imaging with the MWA telescope is feasible with reasonable observing times.Comment: 11 pages, 4 figures, 5 tables, accepted by MNRA

Radio Observations of AGN in Low Surface Brightness Galaxies

We present preliminary results of a study of the low frequency radio continuum emission from the nuclei of Giant Low Surface Brightness (LSB) galaxies. We have mapped the emission and searched for extended features such as radio lobes/jets associated with AGN activity. LSB galaxies are poor in star formation and generally less evolved compared to nearby bright spirals. This paper presents low frequency observations of 3 galaxies; PGC 045080 at 1.4 GHz, 610 MHz, 325MHz, UGC 1922 at 610 MHz and UGC 6614 at 610 MHz. The observations were done with the GMRT. Radio cores as well as extended structures were detected and mapped in all three galaxies; the extended emission may be assocated with jets/lobes associated with AGN activity. Our results indicate that although these galaxies are optically dim, their nuclei can host AGN that are bright in the radio domain.Comment: To appear in proceedings IAU Symp 244, 'Dark Galaxies and Lost Baryons', June 2007, 2 pages including 1 figur

Low radio frequency signatures of ram pressure stripping in Virgo spiral NGC 4254

We report the detection of extended low radio frequency continuum emission beyond the optical disk of the spiral galaxy NGC 4254 using the Giant Metrewave Radio Telescope. NGC 4254, which has an almost face-on orientation, is located in the outskirts of the Virgo cluster. Since such extended emission is uncommon in low inclination galaxies, we believe it is a signature of magnetised plasma pushed out of the disk by ram pressure of the intracluster medium as NGC 4254 falls into the Virgo cluster. The detailed spectral index distribution across NGC 4254 shows that the steepest spectrum alpha < -1 (S propto nu^{alpha}) arises in the gas beyond the optical disk. This lends support to the ram pressure scenario by indicating that the extended emission is not from the disk gas but from matter which has been stripped by ram pressure. The steeper spectrum of the extended emission is reminiscent of haloes in edge-on galaxies. The sharp fall in intensity and enhanced polarization in the south of the galaxy, in addition to enhanced star formation reported by others provide evidence towards the efficacy of ram pressure on this galaxy. HI 21cm observations show that the gas in the north lags in rotation and hence is likely the atomic gas which is carried along with the wind. NGC 4254 is a particularly strong radio emitter with a power of 7x10^{22} Watts/Hz at 240 MHz. We find that the integrated spectrum of the galaxy flattens at lower frequencies and is well explained by an injection spectrum with alpha_0=-0.45+-0.12. We end by comparing published simulation results with our data and conclude that ram pressure stripping is likely to be a significant contributor to evolution of galaxies residing in X-ray poor groups and cluster outskirts.Comment: 10 pages, 7 figures (figures 1,2 and 4 are in jpg format) and 2 tables; Accepted for publication in MNRA

Associated HI absorption in the z=3.4 radio galaxy B2 0902+343 observed with the GMRT

We have made observations of the associated HI absorption of a high redshift radio galaxy 0902+34 at z=3.395 with the Giant Meterwave Radio Telescope in the $323\pm1$ MHz band. We find a narrow absorption line with a flux density of 11.5 mJy at a redshift of 3.397 consistent with that observed by Uson et al. (1991), Briggs et al. (1993) and de Bruyn (1996).A weak broad absorption feature reported by de Bruyn (1996) has not been detected in our observations. We also place an upper limit of 4 mJy (2 $\sigma$) on emission line strength at the position where Uson et al. (1991) claimed to have found a narrow emission line.Comment: To appear in Journal of Astronomy and Astrophysic

Evaluation of rationality of fixed dose combinations of antimicrobials available in Indian market

Background: The antimicrobial resistance is alarming at present. One of the important factors for resistance is use of irrational fixed dose combinations. Thus, objective was to critically analyze the rationality of FDCs of antimicrobial agents currently available in India.Methods: The FDCs of AMAs enlisted in Indian Drug Review 2019 were analyzed by 8 point criteria tool. Analysis includes number of active pharmacological ingredients, approval by central drug standard control organization, listing in world health organization model list of essential medicines (2019) or Government of India national list of essential medicines (2015). Literature search was used for assessing efficacy, safety, pharmacokinetic and pharmacodynamic interactions and advantages of each FDC. Each criterion was assigned score one, if positive and minus one, if negative leading to total score of 12. FDC with score of ≥7 was considered as rational.                                                                         Results: The FDCs of AMA available in Indian market were 116 while FDCs included in WHO model list, 2019 were 24. Majority of FDCs available were irrational that include combination of antibacterial with bromhexine, carbocisteine, ambroxol, serratiopeptidase, antiamoebic and antifungal etc. Most of the rational FDCs belong to antiretroviral, antitubercular and antimalarial drugs.                                Conclusions: Most of the FDCs of AMAs available in Indian market are irrational. These needs educating the prescribers including resident doctors. There is need to critically review such FDCs by drug regulators with strict action regarding manufacturing and marketing

Radio recombination lines from the largest bound atoms in space

In this paper, we report the detection of a series of radio recombination lines (RRLs) in absorption near 26 MHz arising from the largest bound carbon atoms detected in space. These atoms, which are more than a million times larger than the ground state atoms are undergoing delta transitions (n~1009, Delta n=4) in the cool tenuous medium located in the Perseus arm in front of the supernova remnant, Cassiopeia A. Theoretical estimates had shown that atoms which recombined in tenuous media are stable up to quantum levels n~1500. Our data indicates that we have detected radiation from atoms in states very close to this theoretical limit. We also report high signal-to-noise detections of alpha, beta and gamma transitions in carbon atoms arising in the same clouds. In these data, we find that the increase in line widths with quantum number (proportional to n^5) due to pressure and radiation broadening of lines is much gentler than expected from existing models which assume a power law background radiation field. This discrepancy had also been noted earlier. The model line widths had been overestimated since the turnover in radiation field of Cassiopeia A at low frequencies had been ignored. In this paper, we show that, once the spectral turnover is included in the modeling, the slower increase in line width with quantum number is naturally explained.Comment: 5 pages, 4 figures, accepted for publication in MNRA

Evaluation of effect of amitriptyline and pregabalin on heart rate variability in neuropathic pain in non-diabetic patients

Background: The effects of amitriptyline and pregabalin on heart rate variability (HRV) in patients with neuropathic pain in non-diabetic patients are poorly understood in India. The present study was conducted to evaluate the effect of amitriptyline and pregabalin on heart rate variability (HRV) and neuropathic pain in non-diabetic patients.Methods: Forty adult patients (aged 18-65 years) of either sex diagnosed with neuropathic pain were divided into two groups. The study was prospective open label and observational study. Amitriptyline 10 mg once a day was given to group 1 while group 2 received pregabalin 75 mg once a day and HRV and pain score were recorded; and post-treatment data at 2 and 4 weeks were compared with pre-treatment values (control). All the statistical analysis was performed by using Statistical package for social sciences (SPSS) 20.0 software.Results: Both amitriptyline and pregabalin have increased HRV and reduced neuropathic pain intensity after 2- and 4-weeks treatment. The correlation between HRV and neuropathic pain was not observed.Conclusions: To conclude both the drugs have significantly increased HRV and reduced the pain intensity; but no correlation was observed between increased HRV and reduced pain intensity

Multi-wavelength Observations of the Giant X-ray Flare Galaxy NGC 5905: signatures of tidal disruption

NGC 5905 is one of the few galaxies with no prior evidence for an AGN in which an X-ray flare, due to the tidal disruption of a star by the massive black hole in the center of the galaxy, was detected by the RASS in 1990-91. Here we present analysis of late-time follow-up observations of NGC 5905 using Chandra, Spitzer VLA 3 GHz and 8 GHz archival data and GMRT 1.28 GHz radio observations. The X-ray image shows no compact source that could be associated with an AGN. Instead, the emission is extended -- likely due to nuclear star formation and the total measured X-ray luminosity is comparable to the X-ray luminosity determined from the 2002 Chandra observations. Diffuse X-ray emission was detected close to the circum-nuclear star forming ring. The Spitzer 2006 mid-infrared spectrum also shows strong evidence of nuclear star formation but no clear AGN signatures. The semi-analytical models of Tommasin et. al. 2010 together with the measured [OIV]/[NeII] line ratio suggest that at most only 5.6% of the total IR Flux at 19 $\mu$m is being contributed by the AGN. The GMRT 1.28 GHz observations reveal a nuclear source. In the much higher resolution VLA 3 GHz map, the emission has a double lobed structure of size 2.7'' due to the circumnuclear star forming ring. The GMRT 1.28 GHz peak emission coincides with the center of the circumnuclear ring. We did not detect any emission in the VLA 8 GHz (1996) archival data. The 3 $\sigma$ upper limits for the radio afterglow of the TDE at 1.28 GHz, 3 GHz and 8 GHz are 0.17 mJy, 0.09 mJy and 0.09 mJy, respectively. Our studies thus show that (i) NGC 5905 has a declining X-ray flux consistent with a TDE, (ii) the IR flux is dominated by nuclear star formation, (iii) the nuclear radio emission observed from the galaxy is due to circumnuclear star formation, (iv) no compact radio emission associated with a radio afterglow from the TDE is detected.Comment: 12 pages, 8 figures, accepted to be published in Astrophysics and Space Scienc