Legionella and risk management in hospitals - A bibliographic research methodology for people responsible for built environments and facility management

An ongoing research project investigates the roles and duties of persons responsible for the built environment with respect to risk management of water systems and Legionella prevention from a facility management’s perspective. Our literature review provides an approach for selecting and analysing abstracts of initially 177 journal articles, subjected to certain topic-specific inclusion and exclusion criteria. Different decision strategies of either logic ‘yes/no’, Boolean operators ‘OR’ or ‘AND’ and decisions for single counts or cumulative counts of the identified three principal keywords ‘Legionella’, ‘hospital’ and ‘water’, were completed. A final list of ten principal reference articles from 29 journals was compiled. It suggests that the interconnected perspective of water systems, Legionella and hospitals seems to be underrepresented in the field of the built environment and facility management. The term ‘stakeholder’, which would refer to decision-makers, was not found more than once. Our result is a useful summary of established sources of information on environmental Legionella research. The results can be helpful for those new to the topic

SN 2017dio: A Type-Ic Supernova Exploding in a Hydrogen-rich Circumstellar Medium

SN 2017dio shows both spectral characteristics of a type-Ic supernova (SN) and signs of a hydrogen-rich circumstellar medium (CSM). Prominent, narrow emission lines of H and He are superposed on the continuum. Subsequent evolution revealed that the SN ejecta are interacting with the CSM. The initial SN Ic identification was confirmed by removing the CSM interaction component from the spectrum and comparing with known SNe Ic and, reversely, adding a CSM interaction component to the spectra of known SNe Ic and comparing them to SN 2017dio. Excellent agreement was obtained with both procedures, reinforcing the SN Ic classification. The light curve constrains the pre-interaction SN Ic peak absolute magnitude to be around ${M}_{g}=-17.6$ mag. No evidence of significant extinction is found, ruling out a brighter luminosity required by an SN Ia classification. These pieces of evidence support the view that SN 2017dio is an SN Ic, and therefore the first firm case of an SN Ic with signatures of hydrogen-rich CSM in the early spectrum. The CSM is unlikely to have been shaped by steady-state stellar winds. The mass loss of the progenitor star must have been intense, $\dot{M}\sim 0.02{({\epsilon }_{{\rm{H}}\alpha }/0.01)}^{-1}$ (${v}_{\mathrm{wind}}/500$ km s−1) $({v}_{\mathrm{shock}}/$10,000 km s−1)−3 M ⊙ yr−1, peaking at a few decades before the SN. Such a high mass-loss rate might have been experienced by the progenitor through eruptions or binary stripping

Multi-messenger observations of a binary neutron star merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta

SN 2021gno: a calcium-rich transient with double-peaked light curves

We present extensive ultraviolet (UV) and optical photometric and optical spectroscopic follow-up of supernova (SN) 2021gno by the 'Precision Observations of Infant Supernova Explosions' (POISE) project, starting less than 2 d after the explosion. Given its intermediate luminosity, fast photometric evolution, and quick transition to the nebular phase with spectra dominated by [Ca ii] lines, SN 2021gno belongs to the small family of Calcium-rich transients. Moreover, it shows double-peaked light curves, a phenomenon shared with only four other Calcium-rich events. The projected distance from the centre of the host galaxy is not as large as other objects in this family. The initial optical light-curve peaks coincide with a very quick decline of the UV flux, indicating a fast initial cooling phase. Through hydrodynamical modelling of the bolometric light curve and line velocity evolution, we found that the observations are compatible with the explosion of a highly stripped massive star with an ejecta mass of and a 56Ni mass of 0.024 M⊙. The initial cooling phase (first light-curve peak) is explained by the presence of an extended circumstellar material comprising ∼ with an extension of. We discuss if hydrogen features are present in both maximum-light and nebular spectra, and their implications in terms of the proposed progenitor scenarios for Calcium-rich transients

Improved memory behaviour of single-walled carbon nanotube charge storage nodes

To investigate their memory behaviours, single-walled carbon nanotubes (SWCNTs) were embedded in the floating gate of a hybrid metal�insulator�semiconductor structure using layer-by-layer deposition, and polymethylmethacrylate (PMMA) as the dielectric. Unlike longer SWCNT-based structures, shortened SWCNTs were shown to exhibit reliable and large memory windows by virtue of a better encapsulation which reduces charge leakage. The capacitance�voltage characteristics of the devices were consistent with electron injection into the SWCNT charge storage elements (in the floating) from the top electrode through the PMMA, using localized defects and crossing the PMMA energy barrier. In terms of material formulation, a combination of SWCNTs dispersed in sodium dodecyl sulfate and polyethyleneimine used as charge storage elements in the floating gate was shown to lead to repeatable and reliable memory characteristics. Fast switching and very large memory windows (~7 V) exhibiting high charge density (2.6 � 1012 cm�2) and charge retention in excess of ~76% were achieved under a ±10 V sweep voltage range. These results suggest that SWCNTs could lead to improved memory behaviour with the potential for application in plastic electronics

Computational Modelling of Cancer Development and Growth:Modelling at Multiple Scales and Multiscale Modelling

MAJC and CKM gratefully acknowledge support of EPSRC grant no. EP/N014642/1 (EPSRC Centre for Multiscale Soft Tissue Mechanics – With Application to Heart & Cancer).In this paper, we present two mathematical models related to different aspects and scales of cancer growth. The first model is a stochastic spatiotemporal model of both a synthetic gene regulatory network (the example of a three-gene repressilator is given) and an actual gene regulatory network, the NF- κB pathway. The second model is a force-based individual-based model of the development of a solid avascular tumour with specific application to tumour cords, i.e. a mass of cancer cells growing around a central blood vessel. In each case, we compare our computational simulation results with experimental data. In the final discussion section, we outline how to take the work forward through the development of a multiscale model focussed at the cell level. This would incorporate key intracellular signalling pathways associated with cancer within each cell (e.g. p53–Mdm2, NF- κB) and through the use of high-performance computing be capable of simulating up to 109 cells, i.e. the tissue scale. In this way, mathematical models at multiple scales would be combined to formulate a multiscale computational model.PostprintPeer reviewe