β-lactamases em Enterobacteriaceae

UFU - Universidade Federal de UberlândiaTrabalho de Conclusão de Curso (Graduação)Avaliar isolados clínicos de Enterobacteriaceae, quanto à produção de β-lactamases e o perfil de multirresistência. As amostras foram isoladas de um hospital mineiro, de 2014 a 2017 e avaliadas por meio dos antibiogramas e testes fenotípicos de duplo disco para β-lactamases, teste D e sinergismo. Foram recuperadas 93 amostras, a maioria de enfermarias, isoladas de cultura de vigilância e sangue. A bactéria mais presente foi Klebsiella pneumoniae e os pacientes acometidos tinham distribuição diferente, mais homens em UTIs, idade entre 41 e 80 anos e maior ocorrência no ano de 2017. Os mecanismos de resistência mais frequentes foram produção de KPC e ESBL, porém com importante participação das MBL. A endemicidade destes microrganismos implica em um alerta da sua disseminação, pois os mecanismos de resistência encontrados já eram esperados, mas a participação significante de MBL requer um planejamento mais rigoroso de prevenção e controle

Mass Outflow and Chromospheric Activity of Red Giant Stars in Globular Clusters II. M13 and M92

High resolution spectra of 123 red giant stars in the globular cluster M13 and 64 red giant stars in M92 were obtained with Hectochelle at the MMT telescope. Emission and line asymmetries in Halpha, and Ca K are identified, characterizing motions in the extended atmospheres and seeking differences attributable to metallicity in these clusters and M15. On the red giant branch, emission in Halpha generally appears in stars with T_eff < 4500 K and log L/L_sun > 2.75. Fainter stars showing emission are asymptotic giant branch (AGB) stars or perhaps binary stars. The line-bisector for Halpha reveals the onset of chromospheric expansion in stars more luminous than log L/L_sun ~ 2.5 in all clusters, and this outflow velocity increases with stellar luminosity. However, the coolest giants in the metal-rich M13 show greatly reduced outflow in Halpha most probably due to decreased T_eff and changing atmospheric structure. The Ca K_3 outflow velocities are larger than shown by Halpha at the same luminosity and signal accelerating outflows in the chromospheres. Stars clearly on the AGB show faster chromospheric outflows in Halpha than RGB objects. While the Halpha velocities on the RGB are similar for all metallicities, the AGB stars in the metal-poor M15 and M92 have higher outflow velocities than in the metal-rich M13. Comparison of these chromospheric line profiles in the paired metal-poor clusters, M15 and M92 shows remarkable similarities in the presence of emission and dynamical signatures, and does not reveal a source of the `second-parameter' effect.Comment: 41 pages, 14 figures, 11 tables, Accepted in Astronomical Journa

A dwarf nova in the globular cluster M13

Dwarf novae in globular clusters seem to be rare with only 13 detections in the 157 known Galactic globular clusters. We report the identification of a new dwarf nova in M13, the 14th dwarf nova identified in a globular cluster to date. Using the 2m Faulkes Telescope North, we conducted a search for stars in M13 that show variability over a year (2005-2006) on timescales of days and months. This led to the detection of one dwarf nova showing several outbursts. A Chandra X-ray source is coincident with this dwarf nova and shows both a spectrum and variability consistent with that expected from a dwarf nova, thus supporting the identification. We searched for a counterpart in Hubble Space Telescope ACS/WFC archived images and found at least 11 candidates, of which we could characterize only the 7 brightest, including one with a 3 sigma H-alpha excess and a faint blue star. The detection of one dwarf nova when more could have been expected likely indicates that our knowledge of the global Galactic population of cataclysmic variables is too limited. The proportion of dwarf novae may be lower than found in catalogs, or they may have a much smaller duty cycle in general as proposed by some population synthesis models and recent observations in the field.Comment: Accepted for publication in ApJ, 12 pages, 12 figures, 5 tables (v2 contains corrections of the proofs

Nova Geminorum 1912 and the Origin of the Idea of Gravitational Lensing

Einstein's early calculations of gravitational lensing, contained in a scratch notebook and dated to the spring of 1912, are reexamined. A hitherto unknown letter by Einstein suggests that he entertained the idea of explaining the phenomenon of new stars by gravitational lensing in the fall of 1915 much more seriously than was previously assumed. A reexamination of the relevant calculations by Einstein shows that, indeed, at least some of them most likely date from early October 1915. But in support of earlier historical interpretation of Einstein's notes, it is argued that the appearance of Nova Geminorum 1912 (DN Gem) in March 1912 may, in fact, provide a relevant context and motivation for Einstein's lensing calculations on the occasion of his first meeting with Erwin Freundlich during a visit in Berlin in April 1912. We also comment on the significance of Einstein's consideration of gravitational lensing in the fall of 1915 for the reconstruction of Einstein's final steps in his path towards general relativity.Comment: 31 p

Constraining Disk Parameters of Be Stars using Narrowband H-alpha Interferometry with the NPOI

Interferometric observations of two well-known Be stars, gamma Cas and phi Per, were collected and analyzed to determine the spatial characteristics of their circumstellar regions. The observations were obtained using the Navy Prototype Optical Interferometer equipped with custom-made narrowband filters. The filters isolate the H-alpha emission line from the nearby continuum radiation, which results in an increased contrast between the interferometric signature due to the H-alpha-emitting circumstellar region and the central star. Because the narrowband filters do not significantly attenuate the continuum radiation at wavelengths 50 nm or more away from the line, the interferometric signal in the H-alpha channel is calibrated with respect to the continuum channels. The observations used in this study represent the highest spatial resolution measurements of the H-alpha-emitting regions of Be stars obtained to date. These observations allow us to demonstrate for the first time that the intensity distribution in the circumstellar region of a Be star cannot be represented by uniform disk or ring-like structures, whereas a Gaussian intensity distribution appears to be fully consistent with our observations.Comment: 23 pages, 14 figures, accepted for publication in A

Mass Outflow from Red Giant Stars in M13, M15, and M92

Chromospheric model calculations of the Halpha line for selected red giant branch (RGB) and asymptotic giant branch (AGB) stars in the globular clusters M13, M15, and M92 are constructed to derive mass loss rates. The model spectra are compared to the observations obtained with the Hectochelle on the MMT telescope. These stars show strong Halpha emissions and blue-shifted Halpha cores signaling that mass outflow is present in all stars. Outflow velocities of 3-19 km/s, larger than indicated by Halpha profiles, are needed in the upper chromosphere to achieve good agreement between the model spectra and the observations. The resulting mass loss rates range from 0.6*10^{-9} to 5*10^{-9} Msun/yr, which are about an order of magnitude lower than predicted from "Reimers' law" or inferred from the infrared excess of similar stars. The mass loss rate increases slightly with luminosity and with decreasing effective temperature. Stars in the more metal-rich M13 have higher mass loss rates by a factor of ~2 than in the metal-poor clusters M15 and M92. A fit to the mass loss rates is given by: M [Msun/yr] = 0.092 * L^{0.16} * Teff^{-2.02} * A^{0.37} where A=10^[Fe/H]. Multiple observations of stars revealed one object in M15, K757, in which the mass outflow increased by a factor of 6 between two observations separated by 18 months. Other stars showed changes in mass loss rate by a factor of 1.5 or less.Comment: 28 pages, 10 figures, 3 tables, Accepted in Astronomical Journa

Disseminação de microrganismos multirresistentes: uma ameça global e um problema de saúde crítico

Multidrug-resistant organisms are usually associated with greater number of clinical manifestations and severe infections than those caused by susceptible pathogens. The high prevalence of antimicrobial resistance is a global concern, mainly in Latin America, where resistance levels are higher for important pathogens such as Gram-negative non-fermentative bacteria and Enterobacteriacae family, compared with those seen in US hospitals and Europe. The use of antimicrobial agents for the treatment of these infections is advantageous for the multidrug-resistant pathogens and contributes to the maintenance of the genetic determinants of resistance. Countries like Brazil, characterized by the allocation of limited financial resources for the health department, have in the infection prevention and control practices an economical necessity, because of the increased costs that nosocomial infection demand in addition to the reduction of rates morbidity and mortality

Variable stars in the globular cluster M13

Results of a search for variable stars in the central region of the globular cluster M13 are presented. Prior to this study, 36 variable and suspected variable stars were known in this cluster (Osborn 2000; Clement et al. 2001). Of these stars, five were not observed by us. We find v3, v4, v10, v12, and v13 to be constant in light. Surprisingly, only two out of the ten variable star candidates of Kadla et al. (1980) appear to be variable. Both are RRc variables. Additionally, three RR Lyrae stars and one SX Phoenicis variable are discovered. Three close frequencies are detected for an RRc star v36. It appears that this variable is another multi-periodic RR Lyrae star pulsating in non-radial modes. Light curves of the three known BL Herculis stars and all known RR Lyrae stars are presented. The total number of known RR Lyrae stars in M13 is now nine. Only one is an RRab star. The mean period of RRc variables amounts to 0.36 +/- 0.05 d, suggesting that M13 should be included in the group of Oosterhoff type II globular clusters. Mean V magnitudes and ranges of variation are derived for seven RR Lyrae and three BL Herculis variables. Almost all observed bright giants show some degree of variability. In particular, we confirm the variability of two red giants announced to be variable by Osborn (2000) and in addition find five new cases.Comment: 10 pages, 9 figures, 5 tables, accepted for publication in AA

Near-Infrared Variability in the Orion Nebula Cluster

Using the United Kingdom Infrared Telescope on Mauna Kea, we have carried out a new near-infrared J, H, K monitoring survey of almost a square degree of the star-forming Orion Nebula Cluster with observations on 120 nights over three observing seasons, spanning a total of 894 days. We monitored ~15,000 stars down to J=20 using the WFCAM instrument, and have extracted 1203 significantly variable stars from our data. By studying variability in young stellar objects (YSOs) in the H-K, K color-magnitude diagram, we are able to distinguish between physical mechanisms of variability. Many variables show color behavior indicating either dust-extinction or disk/accretion activity, but we find that when monitored for longer periods of time, a number of stars shift between these two variability mechanisms. Further, we show that the intrinsic timescale of disk/accretion variability in young stars is longer than that of dust-extinction variability. We confirm that variability amplitude is statistically correlated with evolutionary class in all bands and colors. Our investigations of these 1203 variables have revealed 73 periodic AA Tau type variables, many large-amplitude and long-period (P > 15 day) YSOs, including three stars showing widely-spaced periodic brightening events consistent with circumbinary disk activity, and four new eclipsing binaries. These phenomena and others indicate the activity of long-term disk/accretion variability processes taking place in young stars. We have made the light curves and associated data for these 1203 variables available online.Comment: Corrected typo in author nam