Complex diffuse radio emission in the merging PLANCK ESZ cluster Abell 3411

We present VLA radio and Chandra X-ray observations of the merging galaxy cluster Abell 3411. For the cluster, we find an overall temperature of 6.4 keV and an X-ray luminosity of 2.8 x 10^{44} erg s^{-1} between 0.5 and 2.0 keV. The Chandra observation reveals the cluster to be undergoing a merger event. The VLA observations show the presence of large-scale diffuse emission in the central region of the cluster, which we classify as a 0.9 Mpc size radio halo. In addition, a complex region of diffuse, polarized emission is found in the southeastern outskirts of the cluster, along the projected merger axis of the system. We classify this region of diffuse emission as a radio relic. The total extent of this radio relic is 1.9 Mpc. For the combined emission in the cluster region, we find a radio spectral index of -1.0 \pm 0.1 between 74 MHz and 1.4 GHz. The morphology of the radio relic is peculiar, as the relic is broken up into five fragments. This suggests that the shock responsible for the relic has been broken up due to interaction with a large-scale galaxy filament connected to the cluster or other substructures in the ICM. Alternatively, the complex morphology reflects the presence of electrons in fossil radio bubbles that are re-accelerated by a shock.Comment: Accepted for publication in ApJ, 8 pages, 5 figure

Internal Colonization of Salmonella enterica Serovar Typhimurium in Tomato Plants

Several Salmonella enterica outbreaks have been traced back to contaminated tomatoes. In this study, the internalization of S. enterica Typhimurium via tomato leaves was investigated as affected by surfactants and bacterial rdar morphotype, which was reported to be important for the environmental persistence and attachment of Salmonella to plants. Surfactants, especially Silwet L-77, promoted ingress and survival of S. enterica Typhimurium in tomato leaves. In each of two experiments, 84 tomato plants were inoculated two to four times before fruiting with GFP-labeled S. enterica Typhimurium strain MAE110 (with rdar morphotype) or MAE119 (without rdar). For each inoculation, single leaflets were dipped in 109 CFU/ml Salmonella suspension with Silwet L-77. Inoculated and adjacent leaflets were tested for Salmonella survival for 3 weeks after each inoculation. The surface and pulp of ripe fruits produced on these plants were also examined for Salmonella. Populations of both Salmonella strains in inoculated leaflets decreased during 2 weeks after inoculation but remained unchanged (at about 104 CFU/g) in week 3. Populations of MAE110 were significantly higher (P<0.05) than those of MAE119 from day 3 after inoculation. In the first year, nine fruits collected from one of the 42 MAE119 inoculated plants were positive for S. enterica Typhimurium. In the second year, Salmonella was detected in adjacent non-inoculated leaves of eight tomato plants (five inoculated with strain MAE110). The pulp of 12 fruits from two plants inoculated with MAE110 was Salmonella positive (about 106 CFU/g). Internalization was confirmed by fluorescence and confocal laser microscopy. For the first time, convincing evidence is presented that S. enterica can move inside tomato plants grown in natural field soil and colonize fruits at high levels without inducing any symptoms, except for a slight reduction in plant growth

Diffusive Evolution of Stable and Metastable Phases II: Theory of Non-Equilibrium Behaviour in Colloid-Polymer Mixtures

By analytically solving some simple models of phase-ordering kinetics, we suggest a mechanism for the onset of non-equilibrium behaviour in colloid-polymer mixtures. These mixtures can function as models of atomic systems; their physics therefore impinges on many areas of thermodynamics and phase-ordering. An exact solution is found for the motion of a single, planar interface separating a growing phase of uniform high density from a supersaturated low density phase, whose diffusive depletion drives the interfacial motion. In addition, an approximate solution is found for the one-dimensional evolution of two interfaces, separated by a slab of a metastable phase at intermediate density. The theory predicts a critical supersaturation of the low-density phase, above which the two interfaces become unbound and the metastable phase grows ad infinitum. The growth of the stable phase is suppressed in this regime.Comment: 27 pages, Latex, eps

The CATERPILLAR-study: An assessor blinded randomized controlled trial comparing a taurolidine-citrate-heparin lock solution to a heparin-only lock solution for the prevention of central-line associated bloodstream infections in paediatric oncology patients

Background: Taurolidine–citrate(–heparin) lock solutions (TCHL) are suggested as a promising and safe method for the prevention of central-line-associated bloodstream infections (CLABSI). Aim: To investigate the efficacy of TCHL for the prevention of CLABSI in paediatric oncology patients. Methods: An assessor-blinded randomized controlled trial at the Princess Máxima Centre for paediatric oncology, the Netherlands, was performed from 2020 to 2023. Paediatric oncology patients receiving a tunnelled central venous access device (CVAD) were eligible. A total of 462 patients were required to compare the TCHL to the heparin-only lock (HL). Patients were followed-up for the first 90 days after CVAD insertion. The primary outcome was the incidence of the first CLABSI from CVAD insertion until the end of follow-up. Intention-to-treat and per-protocol analyses were performed. Findings: In total, 232 were randomized in the HL and 231 in the TCHL group. A total of 47 CLABSIs were observed. The intention-to-treat analysis showed that a CLABSI was observed in 26 (11.2%) of the HL group patients versus 21 (9.1%) of the TCHL group patients; incidence rate ratio (IRR) of 0.81 (95% confidence interval (CI): 0.46–1.45) in favour of the TCHL group. The per-protocol analysis showed that a CLABSI was observed in 10 (7.9%) of the HL group patients versus 6 (4.8%) of the TCHL group patients; IRR of 0.59 (95% CI: 0.21–1.62) in favour of the TCHL group. Adverse events were more common in the TCHL group but rarely reported. Conclusion: No difference was detected between the TCHL and HL in the incidence of CLABSI in paediatric oncology patients

Particle re-acceleration and diffuse radio sources in the galaxy cluster Abell 1550

Context. Radio observations of galaxy clusters reveal a plethora of diffuse, steep-spectrum sources related to the re-acceleration of cosmic-ray electrons, such as halos, relics, and phoenices. In this context, the LOw Frequency ARray Low-Band Antenna (LOFAR-LBA) Sky Survey (LoLSS) provides the most sensitive images of the sky at 54 MHz to date, allowing us to investigate re-acceleration processes in a poorly explored frequency regime. Aims. We study diffuse radio emission in the galaxy cluster Abell 1550, with the aim of constraining particle re-acceleration in the intra-cluster medium. Methods. We exploited observations at four different radio frequencies: 54, 144, 400, and 1400 MHz. To complement our analysis, we made use of archival Chandra X-ray data. Results. At all frequencies we detect an ultra-steep spectrum radio halo (Sν ν1.6) with an extent of 1.2 Mpc at 54 MHz. Its morphology follows the distribution of the thermal intra-cluster medium inferred from the Chandra observation. West of the centrally located head-tail radio galaxy, we detect a radio relic with a projected extent of 500 kpc. From the relic, a 600 kpc long bridge departs and connects with the halo. Between the relic and the radio galaxy, we observe what is most likely a radio phoenix, given its curved spectrum. The phoenix is connected to the tail of the radio galaxy through two arms, which show a nearly constant spectral index for 300 kpc. Conclusions. The halo could be produced by turbulence induced by a major merger, with the merger axis lying in the NE-SW direction. This is supported by the position of the relic, whose origin could be attributed to a shock propagating along the merger axis. It is possible that the same shock has also produced the phoenix through adiabatic compression, while we propose that the bridge could be generated by electrons which were pre-accelerated by the shock, and then re-accelerated by turbulence. Finally, we detect hints of gentle re-energisation in the two arms that depart from the tail of the radio galaxy

The effect of taurolidine on the time-to-positivity of blood cultures

Background: Taurolidine containing lock solutions (TL) are a promising method for the prevention of central line associated bloodstream infections. Per accident, the TL may not always be aspirated from the central venous catheter (CVC) before blood cultures are obtained. The TL could, unintentionally, end up in a blood culture vial, possibly altering the results. The aim of this study was to investigate the effect of the TLs on the detection of microbial growth in blood culture vials. Methods: Different lock solutions (taurolidine-citrate-heparin (TCHL), taurolidine, heparin, citrate or NaCl) were added to BD BACTECTM blood culture vials (Plus Aerobic/F, Lytic/10 Anaerobic/F or Peds Plus/F) before spiking with Staphylococcus aureus (ATCC 29213 or a clinical strain) or Escherichia coli (ATCC 25922 or a clinical strain) in the presence and absence of blood. Subsequently, blood culture vials were incubated in the BD BACTEC FX instrument with Time-to-positivity (TTP) as primary outcome. In addition, the effect of the TCHL on a variety of other micro-organisms was tested. Discussion: In the presence of taurolidine, the TTP was considerably delayed or vials even remained negative as compared to vials containing heparin, citrate or NaCl. This effect was dose-dependent. The delayed TTP was much less pronounced in the presence of blood, but still notable. Conclusion: This study stresses the clinical importance of discarding TLs from the CVC before obtaining a blood culture

The coma cluster at low frequency array frequencies. I. Insights into particle acceleration mechanisms in the radio bridge

Radio synchrotron emission from the bridges of low-density gas connecting galaxy clusters and groups is a challenge for particle acceleration processes. In this work, we analyze the Coma radio bridge using new LOw Frequency ARray (LOFAR) observations at 144 MHz. LOFAR detects the bridge and its substructures with unprecedented sensitivity and resolution. We found that the radio emission peaks on the NGC 4839 group. Toward the halo, in front of the NGC 4839 group, the radio brightness decreases and streams of radio emission connect the NGC 4839 group to the radio relic. Using X-ray observations, we found that thermal and non-thermal plasma are moderately correlated with a sublinear scaling. We use archival radio data at 326 MHz to constrain the spectral index in the bridge, and quantify the distribution of particles and magnetic field at different frequencies. We found that the spectrum is steeper than −1.4 ± 0.2, and that the emission is clumpier at 326 MHz than at 144 MHz. Using cosmological simulations and a simplified approach to compute particle acceleration, we derive under which conditions turbulent acceleration of mildly relativistic electrons generate the radio emission in the bridge. Assuming that the initial energy ratio of the seed electrons is 3 · 10−4 with respect to the thermal gas, we are able to reproduce the observed luminosity. Our results suggest that the seed electrons released by radio galaxies in the bridge and the turbulence generated by the motion of gas and galaxies are essential to producing the radio emission

Physical insights from the spectrum of the radio halo in MACS J0717.5+3745

We present new LOw-Frequency ARray observations of the massive merging galaxy cluster MACS J0717.5+3745, located at a redshift of 0.5458. The cluster hosts the most powerful radio halo known to date. These new observations, in combination with published uGMRT (300-850 MHz) and VLA (1-6.5 GHz) data, reveal that the halo is more extended than previously thought, with a largest linear size of ∼2.2 Mpc, making it one of the largest known halos. The halo shows a steep spectrum (α144 MHz1.5 GHz ∼-1.4) and a steepening (α1.5 GHz5.5 GHz ∼-1.9) above 1.5 GHz. We find a strong scattering in spectral index maps on scales of 50-100 kpc. We suggest that such a strong scattering may be a consequence of the regime where inverse Compton dominates the energy losses of electrons. The spectral index becomes steeper and shows an increased curvature in the outermost regions of the halo. We combined the radio data with Chandra observations to investigate the connection between the thermal and nonthermal components of the intracluster medium (ICM). Despite a significant substructure in the halo emission, the radio brightness correlates strongly with the X-ray brightness at all observed frequencies. The radio-versus-X-ray brightness correlation slope steepens at a higher radio frequency (from b144? MHz? =? 0.67? ±? 0.05 to b3.0? GHz? =? 0.98? ±? 0.09) and the spectral index shows a significant anticorrelation with the X-ray brightness. Both pieces of evidence further support a spectral steepening in the external regions. The compelling evidence for a steep spectral index, the existence of a spectral break above 1.5 GHz, and the dependence of radio and X-ray surface brightness correlation on frequency are interpreted in the context of turbulent reacceleration models. Under this scenario, our results allowed us to constrain that the turbulent kinetic pressure of the ICM is up to 10%