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To describe an outbreak of bacteremia caused by vancomycin-sensitive Enterococcus faecalis (VSEfe).
An investigation by retrospective case control and molecular typing by whole-genome sequencing (WGS).
A tertiary-care neonatal unit in Melbourne, Australia.
Risk factors for 30 consecutive neonates with VSEfe bacteremia from June 2011 to December 2014 were analyzed using a case control study. Controls were neonates matched for gestational age, birth weight, and year of birth. Isolates were typed using WGS, and multilocus sequence typing (MLST) was determined.
Bacteremia for case patients occurred at a median time after delivery of 23.5 days (interquartile range, 14.9–35.8). Previous described risk factors for nosocomial bacteremia did not contribute to excess risk for VSEfe. WGS typing results designated 43% ST179 as well as 14 other sequence types, indicating a polyclonal outbreak. A multimodal intervention that included education, insertion checklists, guidelines on maintenance and access of central lines, adjustments to the late onset sepsis antibiotic treatment, and the introduction of diaper bags for disposal of soiled diapers after being handled inside the bed, led to termination of the outbreak.
Typing using WGS identified this outbreak as predominately nonclonal and therefore not due to cross transmission. A multimodal approach was then sought to reduce the incidence of VSEfe bacteremia.
This article argues that understanding the role of the European Court of Human Rights (ECtHR or the Court) to be that of a guardian of discourse would respect legitimate disagreement among pluralist democracies, while enabling the Court to safeguard human rights in a meaningful and effective way.
From the European Convention on Human Rights (ECHR or the Convention) and the Court's jurisprudence, three basic standards of review can be distilled: First, wherever the Convention's requirements are sufficiently concrete, the Court holds contracting states to well-established standards. Second, when applying broad, abstract and relative Convention rights, the Court safeguards the practical rationality of a democratic decision-making discourse under the rule of law – a substantive review standard that is influenced by procedural factors. Third, the Court also needs to check the facts underlying the case, in order to render its control effective.
By setting ‘soft’ precedent in the form of factors that guide future decision-making without entirely prejudging it, and by taking into account second-order reasons concerning its legitimacy to intervene, the Court is acting as a second player in states’ decision-making discourse. Its task is not to replace the institutions originally responsible for taking the decision, but to ensure that they conform to their own role.
The discovery of the first electromagnetic counterpart to a gravitational wave signal has generated follow-up observations by over 50 facilities world-wide, ushering in the new era of multi-messenger astronomy. In this paper, we present follow-up observations of the gravitational wave event GW170817 and its electromagnetic counterpart SSS17a/DLT17ck (IAU label AT2017gfo) by 14 Australian telescopes and partner observatories as part of Australian-based and Australian-led research programs. We report early- to late-time multi-wavelength observations, including optical imaging and spectroscopy, mid-infrared imaging, radio imaging, and searches for fast radio bursts. Our optical spectra reveal that the transient source emission cooled from approximately 6 400 K to 2 100 K over a 7-d period and produced no significant optical emission lines. The spectral profiles, cooling rate, and photometric light curves are consistent with the expected outburst and subsequent processes of a binary neutron star merger. Star formation in the host galaxy probably ceased at least a Gyr ago, although there is evidence for a galaxy merger. Binary pulsars with short (100 Myr) decay times are therefore unlikely progenitors, but pulsars like PSR B1534+12 with its 2.7 Gyr coalescence time could produce such a merger. The displacement (~2.2 kpc) of the binary star system from the centre of the main galaxy is not unusual for stars in the host galaxy or stars originating in the merging galaxy, and therefore any constraints on the kick velocity imparted to the progenitor are poor.
From five spectrograms obtained at five different positions in the nebula, relative ionic concentrations have been derived with respect to the nucleus. They show that the degree of excitation generally decreases with distance from the nucleus. But there are also areas with locally enhanced or attenuated excitation. Taurus data, a series of two-dimensional monochromatic images centered on (OIII) λ 5007, have been used to construct a two-dimensional velocity map. It shows a large-scale structure similar to the one of direct images with the biconical pattern being at least partly present. Areas of locally lower radial velocity which seem to be inversion symmetrically distributed with respect to the centre, are also distinguished. They do not have pronounced counterparts on direct images. The cavity model suggested by Barral et al. (1982, MNRAS 199, 95) for NGC 6302 and Icke's biconical flow model (1981, Ap. J. 247, 152) are discussed.
Two hypotheses have been put forward for the rôle of binarity in Be stars: (1) All Be stars are interacting binaries. (2) Roughly one-half of the observed Be stars are post-mass exchange binaries with compact companions. Contrary to (1), (2) does not attempt to explain also the existence of disks in Be stars. After the spin-up by mass and angular momentum transfer, the B star somehow has to succeed to form and maintain the disk. Since rapid rotation is only necessary but not sufficient for this transformation, the effect of duplicity would merely be to give more stars the opportunity to become a Be star. Model (1) is not nearly realistic as is also underlined by a new spectroscopic survey for cool companions. The verification of (2) on the basis of the ROSAT All-Sky Survey has just begun; but a serious deficiency of white dwarf companions is already apparent. Binarity currently provides no extra clue on the origin of the Be phenomenon.
Improved observing and data analysis strategies have initiated a considerable expansion of the empirical knowledge about the pulsations of OB stars. Possible correlations between physical parameters and associated pulsation characteristics are becoming more clearly perceivable. This starts to include the asteroseismologically fundamental areas of g-modes and rapid rotation. The β Cephei instability strip continues to be the only locus where radial pulsations occur (but apparently not in all stars located in that strip). Except for spectral types B8/B9 near the main sequence, where pulsations are hardly detected even at low amplitudes, any major group of stars in the Galaxy that are obviously not candidate pulsators still remains to be identified. However, the incidence and amplitudes of OB star pulsations decrease steeply with metallicity. The behaviour of high-luminosity stars is less often dominated by very few modes. In broad-lined stars the moving-bump phenomenon is more common than low-order line-profile variability. But its relation to nonradial pulsation is not clear. The beating of low-ℓ nonradial pulsation modes that have identical angular mode indices may be the clockwork of the outbursts of at least some Be stars. The physics of this episodic mass loss process remains to be identified.
The role of episodic mass loss in evolved massive stars is one of the outstanding questions in stellar evolution theory. Integral field spectroscopy of nebulae around massive stars provide information on their recent mass-loss history. η Car is one of the most massive evolved stars and is surrounded by a complex circumstellar environment. We have conducted a three-dimensional morpho-kinematic analysis of η Car’s ejecta outside its famous Homunculus nebula. SHAPE modelling of VLT MUSE data establish unequivocally the spatial cohesion of the outer ejecta and the correlation of ejecta with the soft X-ray emission.
Be stars (for an in-depth review see Rivinius, Carciofi & Martayan 2013) rotate at ⩾80% of the critical velocity and are multi-mode nonradial pulsators. Magnetic dipole fields are not detected, and binaries with periods less than 30 days are rare. The name-giving emission lines form in a Keplerian decretion disk, which is viscously re-accreted and also radiatively ablated unless replenished by outburts of unknown origin.
Months-long, high-cadence space photometry with the BRITE-Constellation nanosatellites (Pablo et al. 2016) of about 10 early-type Be stars reveals the following (cf. Baade et al. 2016a, Baade et al. 2016b):
○Many Be stars exhibit 1 or 2 so-called Δ frequencies, which are differences between two nonradial-pulsation (NRP) frequencies and much lower (mostly less than 0.1 c/d) than the parent frequencies. The associated light curves are roughly sinusoidal. The amplitudes can exceed that of the sum of the parent amplitudes.
○Conventional beat patterns also occur.
○Amplitudes of both Δ and beat frequencies can temporarily be enhanced. Around phases of maximal amplitude the mean brightness is in- or decreased, and the scatter can be enhanced.
○During high-activity phases (outbursts), broad and dense groups of numerous spikes arise in the power spectra. The two strongest groups often have a frequency ratio near 2. The phase coherence seems to be low.
○Time coverage (less than half a year) is not yet sufficient to infer whether two Δ or beat frequencies can combine to cause long-lasting (years) superoutbursts (cf. Carciofi et al. 2012).
From these observations it is concluded:
•The variable mean brightness and the increased Δ-frequency amplitude and scatter trace the amount of near-circumstellar matter.
•Increase or decrease of mean brightness is aspect-angle dependent (pole-on vs. equator-on).
•Increased amounts of near-circumstellar matter are due to rotation-assisted mass ejections caused by coupled NRP modes.
•Observations do not constrain the location of the coupling (atmosphere or stellar interior).
•Broad frequency groups do not represent stellar pulsation modes but circumstellar variability.
•Be stars later than B5 are less active and may in some cases even behave differently.
We discuss the possible connection between supernova explosions (SN) and gamma-ray bursters (GRB) from the perspective of our current understanding of SN physics. Core collapse supernovae (SN) are the final stages of stellar evolution in massive stars during which the central region collapses, forms a neutron star (NS) or black hole, and the outer layers are ejected. Recent explosion scenarios assumed that the ejection is due to energy deposition by neutrinos into the envelope but detailed models do not produce powerful explosions. There is new and mounting evidence for an asphericity and, in particular, for axial symmetry in several supernovae which may be hard to reconcile within the spherical picture. The 3-D signatures are a key to understand core collapse supernovae and the GRB/SN connection. In this paper we study the effects and observational consequences of asymmetric explosions.
For more than ten years now, a controversial issue in studies of stellar winds has concerned the existence or not of a coronal zone (T ∼ 106 K) at the base of the cool winds (T ∼ Teff) of early-type stars. The latest revival of interest in this possibility is due to Wolfire et al. (1985) who showed that Waldron's (1984) recombination stellar wind (RSW) version of the hot corona – cool wind model (Hearn 1975; Cassinelli et al. 1978) yields models for ξ Puppis (O4 If) that are consistent with both IRAS and Einstein IPC data, thus refuting an earlier claim (Lamers et al. 1984) to have excluded the existence of a coronal zone.
Line profile–variability (LPV) is very wide–spread among early–type stars. With the exception of inhomogeneous surface abundance distributions associated with magnetic fields, the LPV of bona fide non–magnetic stars is consistent with (often only with) nonradial pulsation (NRP). Peculiar surface chemistry and NRP may even be mutually exclusive, and there are other indications that in spite of the ubiquity of NRPs the distribution of their characterizing parameters in the HRD is far from being uniform. This may be important for uncovering the driving mechanism of NRPs in early–type stars.
Following a summary of the observations which suggest that the outbursts of classical Be stars are caused by nonradial pulsations, properties, implications and requirements of a model based on this notion are evaluated. A preliminary analysis of new observations of μ Cen is presented which for the first time in a Be star reveals two relatively closely spaced non–commensurate periods. Such a result would render implausible speculations that the variability of Be stars is due to corotating surface features.
For a discussion of the large-scale structure of spiral nebulae, we should like, of course, to choose a stellar system which we are certain is similar to our own. Since we know that our own Galaxy is a spiral galaxy, this narrows our choice to the spiral galaxies and, of those, we can immediately eliminate the so-called barred spirals, as we know that our galaxy is not a barred spiral. Hence, we need only consider spirals of types Sa, Sb, and Sc on Hubble's system. NGC 4594 is an Sa system with a large central spheroidal system typical of these early-type spirals. Undoubtedly, our Galaxy does not have such a large spheroidal system since it would be obvious as a large bulge which simply has not been observed. Next, M 81 is typical of the Sb spirals in which the central system has shrunk considerably. Finally, M 33 is typical of the Sc spirals in which the central system has shrunk until it actually approaches a semi-stellar point.
A large fraction of Be stars show periodic light and line profile variations with a timescale of about one day. The mechanism which causes these periodic variations has been attributed to nonradial pulsation (NRP) or rotational modulation (RM). The authors present arguments supporting the two opposing points of view with the purpose of stimulating subsequent discussion by the Symposium participants.
Core collapse supernovae (SN) are the final stages of stellar evolution in massive stars during which the central region collapses, forms a neutron star (NS), and the outer layers are ejected. Recent explosion scenarios assumed that the ejection is due to energy deposition by neutrinos into the envelope, but detailed models do not produce powerful explosions. There is new and mounting evidence for an asphericity and, in particular, for axial symmetry in several supernovae which may be hard to reconcile within the spherical picture. This evidence includes the observed high polarization and its variation with time, pulsar kicks, high velocity iron-group and intermediate-mass elements material observed in remnants, direct observations of the debris of SN 1987A, etc. Some of the new evidence is discussed in more detail. To be in agreement with the observations, any successful mechanism must invoke some sort of axial symmetry for the explosion. We consider jet-induced/dominated explosions of core collapse supernovae. Our study is based on detailed 3-d hydrodynamical and radiation transport models. We find that the observations can be explained by low velocity, massive jets which stall well within the SN envelope. Such outflows may be produced by MHD-mechanisms, convective dominated accretion disks on the central object or asymmetric neutrino emissions. Asymmetric density/chemical distributions and, for SN 2002ap, off-center energy depositions have been identified as crucial for the interpretation of the polarization.
66 Oph is a multiple system with a close binary orbiting the B2Ve primary Be star. The binary parameters were derived by two independent methods and spectra of components BA and BB were separated by Fourier disentangling.
We sketch a new method for the accurate flux calibration and normalization of stellar spectra. This is of particular importance for the analysis of rapidly rotating early–type stars. Some preliminary log g determinations by profile fitting of H γ are presented.