Joaquín Ruiz

The AMIGA sample of isolated galaxies - X. A first look at isolated galaxy colors

Context. The basic properties of galaxies can be affected by both nature (internal processes) or nurture (interactions and effects of environment). Deconvolving the two effects is an important current effort in astrophysics. Observed properties of a sample of isolated galaxies should be mainly the result of internal (natural) evolution. It follows that nurture–induced galaxy evolution can only be understood through a comparative study of galaxies in different environments. Aims. We take a first look at SDSS (g − r) colors of galaxies in the AMIGA sample, which consists of many of the most isolated galaxies in the local Universe. This alerted us at the same time to the pitfalls of using automated SDSS colors. Methods. We focused on median values for the principal morphological subtypes found in the AMIGA sample (E/S0 and Sb-Sc) and compared them with equivalent measures obtained for galaxies in denser environments. Results. We find a weak tendency for AMIGA spiral galaxies to be redder than objects in close pairs. We find no clear difference when we compared this with galaxies in other (e.g. group) environments. However, the (g − r) color of isolated galaxies shows a Gaussian distribution, as might be expected assuming nurture-free evolution. We find a smaller median absolute deviation in colors for isolated galaxies compared to both wide and close pairs. The majority of the deviation on median colors for spiral subtypes is caused by a color-luminosity correlation. Surprisingly, isolated and non-isolated early-type galaxies show similar (g −r). We see little evidence for a green valley in our sample because most spirals redder than (g − r) = 0.7 have spurious colors. Conclusions. The redder colors of AMIGA spirals and lower color dispersions for AMIGA subtypes – compared with close pairs – are likely caused by a more passive star formation in very isolated galaxies.

Appearance of resistance to meropenem during the treatment of a patient with meningitis by Acinetobacter

A case is reported of a patient who developed Acinetobacter meningitis after an external ventricular drainage system had been fitted for control of intracranial pressure. During the process, nine strains of Acinetobacter isolated from her cerebrospinal fluid were indistinguishable by analysis of total genomic DNA by pulse-field gel electrophoresis. The first eight strains were sensitive to meropenem and imipenem (MICs < 1 g/l). The MIC of the last one, which had been recovered after 32 days during two courses of treatment with meropenem, increased to > 32 g/l for meropenem, while with imipenem the increase was minimal (MIC = 1.5 g/l). The microorganism persisted in the central nervous system despite the administration of different antimicrobials, including intraventricular aminoglycosides and six changes in the external ventricular system. The patient died 68 days after admission to the intensive care unit from bilateral cerebral ischemic lesions, intraventricular hemorrhage and cerebral edema with endocraneal hypertension, the Acinetobacter ventriculitis also contributing to this state.

When is coagulase-negative Staphylococcus bacteraemia clinically significant?

Abstract Background: Coagulase-negative staphylococci (CoNS) are common contaminants in blood cultures (BC). A prospective study of patients with ≥ 2 blood culture sets and at least 1 positive CoNS BC was performed to develop an algorithm to assist in determining the clinical significance of CoNS bacteraemia. Methods: A single reviewer examined the medical records of patients with CoNS bacteraemia (January–June 2010). The determination of clinical significance was made according to CDC/NHSN (US Centers for Disease Control and Prevention/National Healthcare Safety Network) criteria. To explore risk factors associated with clinical significance, a multivariate analysis was performed. The performances of various algorithms were then compared. An algorithm to assist in determining clinical significance was developed. Results: Two hundred and sixty-nine cases were included; 97 (36%) were considered clinically significant bacteraemia (CSB). Predictors of CSB in the multivariate analysis were: time to positivity < 16 h (odds ratio (OR) 4.540, 95% confidence interval (CI) 1.734–11.884), identification of Staphylococcus epidermidis (OR 4.273, 95% CI 2.124–5.593), central venous catheter (OR 4.932, 95% CI 2.467–9.858), > 2 CoNS-positive bottles from different BC sets (OR 1.957, 95% CI 1.401–2.733), and Charlson score ≥ 3 (OR 2.102, 95% CI 1.078–4.099). The algorithm with best sensitivity (62%) and specificity (93%) for determining clinical significance of CoNS included Charlson score ≥ 3, Pitt score ≥ 1, neutropenic patients, presence of central venous catheter, identification of S. epidermidis, and time to positivity < 16 h. The positive predictive value was 83% and the negative predictive value was 81% (likelihood ratio 8.87). Conclusion: The use of this algorithm could potentially reduce the misclassification of nosocomial bloodstream infections and inappropriate antibiotic treatment in patients for whom a positive CoNS does not represent a CSB.

ARE (PSEUDO)BULGES IN ISOLATED GALAXIES ACTUALLY PRIMORDIAL RELICS

We present structural parameters and (g – i) bulge/disk colors for a large sample (189) of isolated AMIGA galaxies. The structural parameters of bulges were derived from the two-dimensional bulge/disk/bar decomposition of Sloan Digital Sky Survey i-band images using GALFIT. Galaxies were separated between classical bulges (nb > 2.5) and pseudobulges (nb < 2.5), resulting in a dominant pseudobulge population (94%) with only 12 classical bulges. In the μ e -R e plane, pseudobulges are distributed below the elliptical relation (smaller R e and fainter μ e ), with the closest region to the Kormendy relation populated by those pseudobulges with larger values of B/T. We derived (g – i) bulge colors using aperture photometry and find that pseudobulges show median colors (g – i) b ~ 1.06, while their associated disks are much bluer, (g – i) d ~ 0.77. Moreover, 64% (113/177) of pseudobulges follow the red sequence of early-type galaxies. Bluer pseudobulges tend to be located in galaxies with the highest likelihood of tidal perturbation. The red bulge colors and low B/T values for AMIGA isolated galaxies are consistent with an early formation epoch and not much subsequent growth. Properties of bulges in isolated galaxies contrast with a picture where pseudobulges grow continuously via star formation. They also suggest that environment could be playing a role in rejuvenating the pseudobulges.

Catalogues of isolated galaxies, isolated pairs, and isolated triplets in the local Universe

Context. The construction of catalogues of galaxies and the a posteriori study of galaxy properties in relation to their environment have been hampered by scarce redshift information. The new 3-dimensional (3D) surveys permit small, faint, physically bound satellites to be distinguished from a background-projected galaxy population, giving a more comprehensive 3D picture of the surroundings.

The AMIGA sample of isolated galaxies - XII. Revision of the isolation degree for AMIGA galaxies using the SDSS

Context. To understand the evolution of galaxies, it is necessary to have a reference sample where the e ect of the environment is minimized and quantified. In the framework of the AMIGA project (Analysis of the interstellar Medium of Isolated GAlaxies), we present a revision of the environment for galaxies in the Catalogue of Isolated Galaxies (CIG, Karachentseva 1973, Astrof. Issledovaniia Byu. Spec. Ast. Obs., 8, 3) using the ninth data release of the Sloan Digital Sky Survey (SDSS-DR9). Aims. The aims of this study are to refine the photometric-based AMIGA sample of isolated galaxies and to provide an improvement of the quantification of the isolation degree with respect to previous works, using both photometry and spectroscopy. Methods. We developed an automatic method to search for neighbours within a projected area of 1 Mpc radius centred on each primary galaxy to revise the CIG isolation criteria introduced by Karachentseva (1973). The local number density at the fifth nearest neighbour and the tidal strength a ecting the CIG galaxy were estimated to quantify the isolation degree. Results. Of the 636 CIG galaxies considered in the photometric study, 426 galaxies fulfil the CIG isolation criteria within 1 Mpc, taking into account projected neighbours. Of the 411 CIG galaxies considered in the spectroscopic study, 347 galaxies fulfil the CIG isolation criteria when a criterion about redshift di erence is added. The available redshifts allow us to reject background neighbours and thus improve the photometric assessment. On average, galaxies in the AMIGA sample show lower values in the local number density and the tidal strength parameters than galaxies in denser environments such as pairs, triplets, compact groups, and clusters. Conclusions. For the first time, the environment and the isolation degree of AMIGA galaxies are quantified using digital data. The use of the SDSS database permits one to identify fainter and smaller-size satellites than in previous AMIGA works. The AMIGA sample is improved by this study, because we reduced the sample of isolated galaxies used in previous AMIGA works by about 20%. The availability of the spectroscopic data allows us to check the validity of the CIG isolation criteria, which is not fully e cient. About 50% of the neighbours considered as potential companions in the photometric study are in fact background objects. We also find that about 92% of the neighbour galaxies that show recession velocities similar to the corresponding CIG galaxy are not considered by the CIG isolation criteria as potential companions, which may have a considerable influence on the evolution of the central CIG galaxy.

What is the impact of a rapid diagnostic E-test in the treatment of patients with Gram-negative bacteraemia?

Abstract Objective: To evaluate the influence of a rapid diagnostic test (RDT) in antibiotic therapeutic decisions in non-paediatric patients with Gram-negative bacteraemia (GNB). Patients and methods: A RDT consisting of a direct antibiogram was used on blood isolates of GNB. GNB were also identified and sensitivity tests were performed according to standard criteria. Information on empirical treatment was registered (T1), as well as the antibiotic administered once the results of the RDT were available (T2). Finally, we noted the ideal antibiotic that the infectious diseases specialist (IDS) would have prescribed (T3). The decision regarding T2 was always taken by the patients physician or the physician on duty. Results: A RDT was performed for 248 patients. The most frequently isolated bacterium was Escherichia coli (13% producing extended-spectrum beta-lactamase). T1 was considered appropriate in 74% and appropriate but optimizable in 43%. T2 was considered appropriate in 95%, appropriate but optimizable in 36%, and inappropriate in 5%. The cost of the optimizable treatment (T2) was € 2210, while the cost of the ideal treatment would have been € 416; the saving in antibiotic cost of 1 day of treatment would have been € 1694. Conclusions: Treatment prescribed by a non-IDS after a RDT was inappropriate in 5% and optimizable in 36%. It is our recommendation that information provided by a RDT should be interpreted by an IDS to make the information more beneficial both economically and ‘ecologically’.

Effectiveness of Immunomodulating Treatment (Thymostimulin) in Chronic Obstructive Pulmonary Disease

We conducted a prospective randomized study to assess the effect of thymostimulin in patients with long-standing chronic obstructive pulmonary disease (COPD) during a 1-year follow-up. A total of 38 patients in the intervention group and 40 in the control group received standard treatment for COPD. Patients in the intervention group were also given thymostimulin intramuscularly (1 mg/kg day for the 1st week followed by once a week for 6 months). At the end of the study period, patients treated with thymostimulin showed a statistically significant lower number of exacerbations and hospital admissions as compared with controls. However, there were no changes in the number of patients with severe or moderate impairment of respiratory function throughout the study period. No significant differences were found by Multitest or in serum concentrations of immunoglobulins and T-cell subsets before and after thymostimulin treatment. We conclude that treatment with thymostimulin is effective in the prevention of COPD exacerbations acting on the cellular immune response involved in bronchopulmonary defense.

LSSGalPy: Interactive Visualization of the Large-scale Environment Around Galaxies

New tools are needed to handle the growth of data in astrophysics delivered by recent and upcoming surveys. We aim to build open-source, light, flexible, and interactive software designed to visualize extensive three-dimensional (3D) tabular data. Entirely written in the Python language, we have developed interactive tools to browse and visualize the positions of galaxies in the universe and their positions with respect to its large-scale structures (LSS). Motivated by a previous study, we created two codes using Mollweide projection and wedge diagram visualizations, where survey galaxies can be overplotted on the LSS of the universe. These are interactive representations where the visualizations can be controlled by widgets. We have released these open-source codes that have been designed to be easily re-used and customized by the scientific community to fulfill their needs. The codes are adaptable to other kinds of 3D tabular data and are robust enough to handle several millions of objects.