Experience of Laparoscopic Cholecystectomy at Lumbini Medical College Teaching Hospital

  Introduction: The difficult gallbladder is the most common difficult laparoscopy being performed by generalsurgeons all over the world and the potential one that places the patient at significant risk. The present study aimed to study all the cases of laparoscopic cholecystectomy conducted in current setup at Lumbini Medical College and Teaching Hospital, to compare the results with the published literature and also analyze the complications and ways to decrease the incidence of conversion to open procedure.   Methods: Five hundred twenty five patients age 10-90 years, male:female ratio of 1:3.86 with body weight 45-65 kilogram, who had undergone laparoscopic cholecystectomy for symptomatic cholelithiasis without choledocholithiasis from April 2011 to April 2013 were studied.   Results: All the laparoscopic cholecystectomy (LC) were without major complications. Only nineteen out of five hundred twentyfive (3.6%) required conversion to open cholecystectomy (OC). Reasons for conversion included: dense omental or visceral adhesions; two (0.38%), unclear anatomy; 16 (3.04%), common bile duct injury; one (0.19%). There were 20 cases of shrunken gallbladder suspicious of malignancy but didn’t required conversion.   Conclusion: Laparoscopic cholecystectomy is the preferred method in our setup even in difficult cases

Optical Properties of High-Frequency Radio Sources from the Australia Telescope 20 GHz (AT20G) Survey

Our current understanding of radio-loud AGN comes predominantly from studies at frequencies of 5 GHz and below. With the recent completion of the Australia Telescope 20 GHz (AT20G) survey, we can now gain insight into the high-frequency radio properties of AGN. This paper presents supplementary information on the AT20G sources in the form of optical counterparts and redshifts. Optical counterparts were identified using the SuperCOSMOS database and redshifts were found from either the 6dF Galaxy survey or the literature. We also report 144 new redshifts. For AT20G sources outside the Galactic plane, 78.5% have optical identifications and 30.9% have redshift information. The optical identification rate also increases with increasing flux density. Targets which had optical spectra available were examined to obtain a spectral classification. There appear to be two distinct AT20G populations; the high luminosity quasars that are generally associated with point-source optical counterparts and exhibit strong emission lines in the optical spectrum, and the lower luminosity radio galaxies that are generally associated with passive galaxies in both the optical images and spectroscopic properties. It is suggested that these different populations can be associated with different accretion modes (cold-mode or hot-mode). We find that the cold-mode sources have a steeper spectral index and produce more luminous radio lobes, but generally reside in smaller host galaxies than their hot-mode counterparts. This can be attributed to the fact that they are accreting material more efficiently. Lastly, we compare the AT20G survey with the S-cubed semi-empirical (S3-SEX) models and conclude that the S3-SEX models need refining to correctly model the compact cores of AGN. The AT20G survey provides the ideal sample to do this.Comment: Accepted for publication in MNRA

The Australia Telescope 20GHz (AT20G) Survey: analysis of the extragalactic source sample

The Australia Telescope 20 GHz (AT20G) survey is a blind survey of the whole Southern sky at 20 GHz with follow-up observations at 4.8, 8.6, and 20 GHz carried out with the Australia Telescope Compact Array (ATCA). In this paper we present an analysis of radio spectral properties in total intensity and polarisation, sizes, optical identifications, and redshifts of the sample of the 5808 extragalactic sources in the survey catalogue of confirmed sources over the whole Southern sky excluding the strip at Galactic latitude |b|<1.5deg. The sample has a flux density limit of 40 mJy. Completeness has been measured as a function of scan region and flux density. Averaging over the whole survey area the follow-up survey is 78% complete above 50mJy and 93% complete above 100mJy. 3332 sources with declination <-15deg have good quality almost simultaneous observations at 4.8, 8.6, and 20GHz. The spectral analysis shows that the sample is dominated by flat-spectrum sources. The fraction of flat-spectrum sources decreases from 81% for 20GHz flux densities S>500mJy, to 60% for S<100mJy. There is also a clear spectral steepening at higher frequencies with the median spectral index decreasing from -0.16 between 4.8 and 8.6GHz to -0.28 between 8.6 and 20GHz. Simultaneous observations in polarisation are available for all the sources at all the frequencies. 768 sources have a good quality detection of polarised flux density at 20GHz; 467 of them were also detected in polarisation at 4.8 and/or at 8.6GHz so that it has been possible to compare the spectral behaviour in total intensity and polarisation. We have found that the polarised fraction increases slightly with frequency and decreases with flux density. Cross matches and comparisons have been made with other catalogues at lower radio frequencies, and in the optical, X-ray and gamma-ray bands. Redshift estimates are available for 825 sources.Comment: 15 pages, 16 figures, accepted for publication in MNRA

The FLASH pilot survey: An H i absorption search against MRC 1-Jy radio sources

We report an ASKAP search for associated H i 21-cm absorption against bright radio sources from the Molonglo Reference Catalogue (MRC) 1-Jy sample. The search uses pilot survey data from the ASKAP First Large Absorption Survey in H i (FLASH) covering the redshift range 0.42 < z < 1.00. From a sample of 62 MRC 1-Jy radio galaxies and quasars, we report three new detections of associated H i 21-cm absorption, yielding an overall detection fraction of. The detected systems comprise two radio galaxies (MRC 2216-281 at z = 0.657 and MRC 0531-237 at z = 0.851) and one quasar (MRC 2156-245 at z = 0.862). The MRC 0531-237 absorption system is the strongest found to date, with a velocity integrated optical depth of. All three objects with detected H i 21-cm absorption are peaked-spectrum or compact steep-spectrum (CSS) radio sources. Two of them show strong interplanetary scintillation at 162 MHz, implying that the radio continuum source is smaller than 1 arcsec in size even at low frequencies. Among the class of peaked-spectrum and compact steep-spectrum radio sources, the H i detection fraction is. All three detections have a high 1.4 GHz radio luminosity, with MRC 0531-237 and MRC 2216-281 having the highest values in the sample,. The preponderance of extended radio sources in our sample could partially explain the overall low detection fraction, while the effects of a redshift evolution in gas properties and AGN UV luminosity on the neutral gas absorption still need to be investigated

The FLASH pilot survey: an HI absorption search against MRC 1-Jy radio sources

We report an ASKAP search for associated HI 21-cm absorption against bright radio sources from the Molonglo Reference Catalogue (MRC) 1-Jy sample. The search uses pilot survey data from the ASKAP First Large Absorption Survey in \hi (FLASH) covering the redshift range $0.42 < z < 1.00$. From a sample of 62 MRC 1-Jy radio galaxies and quasars in this redshift range we report three new detections of associated HI 21-cm absorption, yielding an overall detection fraction of $1.8\%^{+4.0\%}_{-1.5\%}$. The detected systems comprise two radio galaxies (MRC 2216$-$281 at $z=0.657$ and MRC 0531$-$237 at $z=0.851$) and one quasar (MRC 2156$-$245 at $z=0.862$). The MRC 0531$-$237 absorption system is the strongest found to date, with a velocity integrated optical depth of $\rm 143.8 \pm 0.4 \ km \ s^{-1}$. All three objects with detected HI 21-cm absorption are peaked-spectrum or compact steep-spectrum (CSS) radio sources, classified based on our SED fits to the spectra. Two of them show strong interplanetary scintillation at 162 MHz, implying that the radio continuum source is smaller than 1 arcsec in size even at low frequencies. Among the class of peaked-spectrum and compact steep-spectrum radio sources, the HI detection fraction is $23\%^{+22\%}_{-13\%}$. This is consistent within $1\sigma$ with a detection fraction of $\approx 42\%^{+21\%}_{-15\%}$ in earlier reported GPS and CSS samples at intermediate redshifts ($0.4 < z < 1.0$). All three detections have a high 1.4 GHz radio luminosity, with MRC 0531$-$237 and MRC 2216$-$281 having the highest values in the sample, $\rm > 27.5 \ W \ Hz^{-1}$. The preponderance of extended radio sources in our sample could partially explain the overall low detection fraction, while the effects of a redshift evolution in gas properties and AGN UV luminosity on the neutral gas absorption still need to be investigated.Comment: 28 pages, 9 figures and 7 Tables. Submitted to MNRA

The Australia Telescope 20 GHz Survey: The Source Catalogue

We present the full source catalogue from the Australia Telescope 20 GHz (AT20G) Survey. The AT20G is a blind radio survey carried out at 20 GHz with the Australia Telescope Compact Array (ATCA) from 2004 to 2008, and covers the whole sky south of declination 0 deg. The AT20G source catalogue presented here is an order of magnitude larger than any previous catalogue of high-frequency radio sources, and includes 5890 sources above a 20 GHz flux-density limit of 40 mJy. All AT20G sources have total intensity and polarisation measured at 20 GHz, and most sources south of declination -15 deg also have near-simultaneous flux-density measurements at 5 and 8 GHz. A total of 1559 sources were detected in polarised total intensity at one or more of the three frequencies. We detect a small but significant population of non-thermal sources that are either undetected or have only weak detections in low-frequency catalogues. We introduce the term Ultra-Inverted Spectrum (UIS) to describe these radio sources, which have a spectral index alpha(5, 20) > +0.7 and which constitute roughly 1.2 per cent of the AT20G sample. The 20 GHz flux densities measured for the strongest AT20G sources are in excellent agreement with the WMAP 5-year source catalogue of Wright et al. (2009), and we find that the WMAP source catalogue is close to complete for sources stronger than 1.5 Jy at 23 GHz.Comment: 21 pages, accepted for publication in MNRA

Quasars, Radio Galaxies and Gravitational Lenses in the High Radio Frequency Universe

I present the interferometry visibility catalogue for > 94 % of sources in the Australia Telescope 20 GHz (AT20G) survey covering all de- clinations of the Southern hemisphere. The catalogue was obtained utilizing the additional dataset from the sixth antenna (with long &#8764; 4500 m baselines) of the Australia Telescope Compact Array (ATCA) in the main AT20G survey follow-up observations at 18.8 GHz. It provides angular size information at subarcsec (&#8764; 0.1 arcsec) resolution. Applications of the visibility catalogue in different fields - study of radio spectra of AGNs and AGN powered radio sources; the effect of spectral curvature at high radio frequencies on redshift cut-off of compact AGNs and search for gravitational lenses in the southern hemisphere - are presented in detail.The visibility amplitudes were calculated using a non-standard method using scalar averaging of the visibility amplitudes. The missing visibilities, due to observational logistics, do not introduce bias and, hence, the catalogue has the same completeness and reliability level corresponding to the AT20G survey. Most sources have visibilities measured at two widely separated hour angles and are presented as independent numbers, providing limited morphological information about the sources.The visibility corresponding to 0.14 arcsec was used to separate the sources into compact and extended extragalactic sources. 77% of the AT20G sources are found to be compact AGNs. Cross matches with lower frequency radio surveys the 1.4 GHz NRAO VLA Sky Survey (NVSS) and the 0.8 GHz Sydney University Molonglo Sky Survey (SUMSS) combined with the AT20G observations at 5 and 8 GHz are used to study the spectra of the sources from lower frequencies to 20 GHz. The limitations of spectral index at higher radio frequencies as a diagnostic for separating compact and extended sources is discussed. A visibility-spectra diagnostic plot that is capable of cleanly separating different classes of extragalactic sources is introduced. Discussion of properties of sources from cross matches with optical, ROSAT X- ray and Fermi gamma-ray catalogues is presented. Galactic free-free thermal planetary nebulae that were easily detected in this visibility-spectra plot are listed in the appendix.A physical basis for the use of spectral index to select compact and extended extragalactic sources at lower frequencies is provided, with recommendations for the use of &#957;&#8722;0.5 as the limit in future studies to maintain consistency. A moustache plot for compact AGNs showing spectral curvature at higher rest frame frequencies is presented. Discussions supporting the validity of studies concentrating on redshift cut-off of flat-spectrum compact AGNs at lower frequencies is presented. The results showing redshift cut-off is affected by spectral steepening at higher observed frequencies is also presented.A search for gravitational lensing in the southern hemisphere using the visibility data and follow-up imaging observations at 7 mm and with the Gemini South 8 m optical telescope are presented. The motivation, the strategy pushing the boundaries of the available instrument, the data reduction steps and the results are presented. Awaiting further data processing, one source is identified as most likely case of gravitational lens system and three are listed as candidates, result consistent with the successful northern hemisphere Cosmic Lens All Sky Survey (CLASS) results