The Nuclear Activity of the Galaxies in the Hickson Compact Groups

In order to investigate the nuclear activity of galaxies residing in compact groups of galaxies, we present results of our optical spectroscopic program made at Okayama Astrophysical Observatory. We have performed optical spectroscopy of 69 galaxies which belong to 31 Hickson Compact Groups (HCGs) of Galaxies. Among them, three galaxies have discordant redshifts. Further, spectral quality is too poor to classify other three galaxies. Therefore, we describe our results for the remaining 63 galaxies. Our main results are summarized below. (1) We have found in our sample; 28 AGN, 16 HII nuclei, and 19 normal galaxies which show no emission line. We used this HCG sample for statistical analyses. (2) Comparing the frequency distributions of activity types between the HCGs and the field galaxies whose data are taken from Ho, Filippenko, & Sargent (382 field galaxies), we find that the frequency of HII nuclei in the HCGs is significantly less than that in the field. However, this difference may be due to selection bias that our HCG sample contains more early-type galaxies than the field, because it is known that HII nuclei are rarer in early-type galaxies than in later ones. (3) Applying correction this morphological bias to the HCG sample, we find that there is no statistically significant difference in the frequency of occurrence of emission-line galaxies between the HCGs and the field. This implies that the dense galaxy environment in the HCGs does not affect triggering both the AGN activity and the nuclear starburst. We discuss some implications on the nuclear activity in the HCG galaxies.Comment: 33 pages (3 aasms4 LaTeX files), 5 figures (5 Postscript files: excluded Figure 1), Accepted for publication in The Astronomical Journa

A search for nuclear disintegrations produced by slow negative heavy mesons

This paper describes the preliminary results of a search for evidence of the nuclear interactions of negative heavy mesons. A qualitative analysis is given of the possible characteristics of their interactions and the appearance these might be expected to have in photographic emulsions. 37 ml. of emulsion, in which are recorded 10 000 stars and 1200 slow π-mesons, have been completely examined. In the conditions of exposure, such a volume should contain six examples, with good geometry, of the decay of heavy mesons. Mass measurements have been carried out, by the range/scattering method, on 417 tracks of σ-mesons. In addition, 1800 σ-mesons, observed in 42 ml. of emulsion, have been examined. No disintegrations which can be attributed to heavy mesons have been found. The results suggest that some of the negative heavy mesons, on being brought to rest in photographic emulsions, behave in a manner qualitatively different from that of negative π-particles. Possible explanations for this result are suggested

Limits on monopole fluxes from KFG experiment

The nucleon decay experiment at KGF at a depth of 2.3 Km is eminently suited for the search of Grand Unified theory (GUT) monopoles, whose velocities at the present epoch are predicted to be around 0.001C. At this depth the cosmic ray background is at a level 2/day in the detector of size 4m x 6m x 3.7m and one can look for monopoles traversing the detector in all directions, using three methods, i.e., (1) dE/dx (ionization); (2) time of flight and (3) catalysis of nucleon decay. The detector is composed of 34 layers of proportional counters arranged in horizontal planes one above the other in an orthogonal maxtrix. Each of the 1594 counters are instrumented to measure ionization in the gas (90% Argon + 10% Methane) as well as the time of arrival of particles

Infrared emission from compact groups of galaxies

A search of the IRAS Point Source Catalog, Version 2 has revealed infrared sources within 1 arcmin of the optical centers of 54 gal axies in Hickson's catalog of compact groups of galaxies. The 60μm luminosity function for these galaxies has the same shape as the luminosity function of the IRAS bright galaxy sample. The space density of IRAS galaxies in compact groups is 60 times smaller than the space density of IRAS bright galaxies, indicating that of order 1% of all bright IRAS galaxies are in compact groups. The infrared emission from these galaxies is compared with the emission from samples of isolated galaxies by Keel et aI. and cluster galaxies studied by Bicay and Giovanelli . The fractional distribution of the ratio of far-infrared to optical luminosity of compact group galaxies is significantly larger than that of the isolated galaxies and comparable to that of the cluster galaxies. These results indicate that infrared emission is enhanced in the compact group galaxies, probably because of interactions. We also report an upper limit to the 2-10 keV X-ray flux of compact groups in our sample of 3χ 1041h-2 ergs-1, from the HEAO I A-2 experiment

Clinical and economic consequences of hospital-acquired resistant and multidrug-resistant Pseudomonas aeruginosa infections: a systematic review and meta-analysis

Background Increasing rates of resistant and multidrug-resistant (MDR) P. aeruginosa in hospitalized patients constitute a major public health threat. We present a systematic review of the clinical and economic impact of this resistant pathogen. Methods Studies indexed in MEDLINE and Cochrane databases between January 2000-February 2013, and reported all-cause mortality, length of stay, hospital costs, readmission, or recurrence in at least 20 hospitalized patients with laboratory confirmed resistant P. aeruginosa infection were included. We accepted individual study definitions of MDR, and assessed study methodological quality. Results The most common definition of MDR was resistance to more than one agent in three or more categories of antibiotics. Twenty-three studies (7,881 patients with susceptible P. aeruginosa, 1,653 with resistant P. aeruginosa, 559 with MDR P. aeruginosa, 387 non-infected patients without P. aeruginosa) were analyzed. A random effects model meta-analysis was feasible for the endpoint of all-cause in-hospital mortality. All-cause mortality was 34% (95% confidence interval (CI) 27% – 41%) in patients with any resistant P. aeruginosa compared to 22% (95% CI 14% – 29%) with susceptible P. aeruginosa. The meta-analysis demonstrated a > 2-fold increased risk of mortality with MDR P. aeruginosa (relative risk (RR) 2.34, 95% CI 1.53 – 3.57) and a 24% increased risk with resistant P. aeruginosa (RR 1.24, 95% CI 1.11 – 1.38), compared to susceptible P. aeruginosa. An adjusted meta-analysis of data from seven studies demonstrated a statistically non-significant increased risk of mortality in patients with any resistant P. aeruginosa (adjusted RR 1.24, 95% CI 0.98 – 1.57). All three studies that reported infection-related mortality found a statistically significantly increased risk in patients with MDR P. aeruginosa compared to those with susceptible P. aeruginosa. Across studies, hospital length of stay (LOS) was higher in patients with resistant and MDR P. aeruginosa infections, compared to susceptible P. aeruginosa and control patients. Limitations included heterogeneity in MDR definition, restriction to nosocomial infections, and potential confounding in analyses. Conclusions Hospitalized patients with resistant and MDR P. aeruginosa infections appear to have increased all-cause mortality and LOS. The negative clinical and economic impact of these pathogens warrants in-depth evaluation of optimal infection prevention and stewardship strategies

Results on nucleon life-time from the Kolar gold field experiment

The KGF nucleon decay experiment has been in operation since October 1980 with a 140 ton calorimetric detector at a depth of 2.3 Km underground. The detector comprises 34 layers of proportional counters arranged in an orthogonal geometry with 12 mm thick iron plates in between successive layers. The proportional counters are made up of square (10 x 10 square centimeters) iron plates of wall thickness 2.3 mm. Each of the 1600 counters is instrumented to provide data on ionization, DE/dx and arrival time. The visible energy of a particle is determined to an accuracy of approximately 20% from the ionization and range of its track. The end point ionization of a stopping track provides the direction of motion as well as the nature of the particle (mu/pi,k,p). Decay of mu is recorded with an overall efficiency of only 20% in view of the thickness of 13 g/square centimeters between successive layers

Data acquisition system for phase-2 KGF proton decay experiment

Phase-2 of KGF proton decay experiment using 4000 proportional counters will start operating from middle of 1985. The detection systems, in addition to measuring the time information to an accuracy of 200 n see, also records ionization in the hit counters. It also monitors different characteristics of the counters like pulse height spectrum, pulse width spectrum and counting rate. The acquisition system is discussed