Spectral analysis and kinetic modeling of radioluminescence in air and nitrogen.

In this article we present a quantitative analysis of the second positive system of molecular nitrogen and the first negative system of the molecular nitrogen cation excited in the presence of ionizing radiation. Optical emission spectra of atmospheric air and nitrogen surrounding 210Po sources were measured from 250 to 400 nm. Multi-Boltzmann and non-Boltzmann vibrational distribution spectral models were used to determine the vibrational temperature and vibrational distribution function of the emitting N2(C3Πu) and N2+(B2Σ+u) states. A zero-dimensional kinetic model, based on the electron energy distribution function (EEDF) and steady-state excitation and de-excitation of N2(X1Σ+g), N2+(B2Σ+u), N2+(X2Σ+g), N4+, O2+, and N2(C3Πu, v), was developed for the prediction of the relative spectral intensity of both the N2+(B2Σ+u → X2Σ+g) emission band and the vibrational bands of N2(C3Πu → B3Πg) for comparison with the experimental data.

Can the Reboot coaching programme support critical care nurses in coping with stressful clinical events? A mixed-methods evaluation assessing resilience, burnout, depression and turnover intentions.

BACKGROUND: Critical care nurses (CCNs) are routinely exposed to highly stressful situations, and at high-risk of suffering from work-related stress and developing burnout. Thus, supporting CCN wellbeing is crucial. One approach for delivering this support is by preparing CCNs for situations they may encounter, drawing on evidence-based techniques to strengthen psychological coping strategies. The current study tailored a Resilience-boosting psychological coaching programme [Reboot] to CCNs. Other healthcare staff receiving Reboot have reported improvements in confidence in coping with stressful clinical events and increased psychological resilience. The current study tailored Reboot for online, remote delivery to CCNs (as it had not previously been delivered to nurses, or in remote format), to (1) assess the feasibility of delivering Reboot remotely, and to (2) provide a preliminary assessment of whether Reboot could increase resilience, confidence in coping with adverse events and burnout. METHODS: A single-arm mixed-methods (questionnaires, interviews) before-after feasibility study design was used. Feasibility was measured via demand, recruitment, and retention (recruitment goal: 80 CCNs, retention goal: 70% of recruited CCNs). Potential efficacy was measured via questionnaires at five timepoints; measures included confidence in coping with adverse events (Confidence scale), Resilience (Brief Resilience Scale), depression (PHQ-9) and burnout (Oldenburg-Burnout-Inventory). Intention to leave (current role, nursing more generally) was measured post-intervention. Interviews were analysed using Reflexive Thematic Analysis. RESULTS: Results suggest that delivering Reboot remotely is feasible and acceptable. Seventy-seven nurses were recruited, 81% of whom completed the 8-week intervention. Thus, the retention rate was over 10% higher than the target. Regarding preliminary efficacy, follow-up measures showed significant increases in resilience, confidence in coping with adverse events and reductions in depression, burnout, and intention to leave. Qualitative analysis suggested that CCNs found the psychological techniques helpful and particularly valued practical exercises that could be translated into everyday practice. CONCLUSION: This study demonstrates the feasibility of remote delivery of Reboot and potential efficacy for CCNs. Results are limited due to the single-arm feasibility design; thus, a larger trial with a control group is needed.

Quantitative Determination of Metal Ion Adsorption on Cellulose Nanocrystals Surfaces.

Nanocellulose is a bio-based material that holds significant potential in the field of water purification. Of particular interest is their potential use as a key sorbent material for the removal of metal ions from solution. However, the structure of metal ions adsorbed onto cellulose surfaces is not well understood. The focus of this work is to determine quantitatively the three-dimensional distribution of metal ions of different valencies surrounding negatively charged carboxylate functionalized cellulose nanocrystals (CNCs) using anomalous small-angle X-ray scattering (ASAXS). These distributions can affect the water and ionic permeability in these materials. The data show that increasing the carboxylate density on the surface of the CNCs from 740 to 1100 mmol/kg changed the nature of the structure of the adsorbed ions from a monolayer into a multilayer structure. The monolayer was modeled as a Stern layer around the CNC nanoparticles, whereas the multilayer structure was modeled as a diffuse layer on top of the Stern layer around the nanoparticles. Within the Stern layer, the maximum ion density increases from 1680 to 4350 mmol of Rb+/(kg of CNC) with the increase in the carboxylate density on the surface of the nanoparticles. Additionally, the data show that CNCs can leverage multiple mechanisms, such as electrostatic attraction and the chaotropic effect, to adsorb ions of different valencies. By understanding the spatial organization of the adsorbed metal ions, the design of cellulose-based sorbents can be further optimized to improve the uptake capacity and selectivity in separation applications.

Decoding the decisive role of seed moisture content in physical dormancy break: filling the missing links.

Species producing seeds with a water-impermeable seed coat, i.e., physical dormancy (PY), dominate the dry tropical forests. Despite increasing interest and understanding of the germination ecology of a PY species, less is known about how PY break occurs, particularly what changes lead to the opening of the 'water gap'. Based on the moisture conent (MC) attained, two ranges of PY may exist: shallow PY, a state with higher MC and seeds could reverse to a permeable state when the relative humidity increases; and absolute PY, a completely dry state. Here, we demonstrate that this MC variation between seeds affects preconditioning and the 'water-gap' opening stages. A conceptual model developed shows a strong relationship between temperature and duration, with high temperature breaking PY in seconds, but seasonal temperature fluctuations and constant temperatures require a longer time. The duration required at any conditions to break PY is purported to depend on the hydrophobic bonds of the lipids, which are likely weakened during the preconditioning, and the amount of water influences hydrolysis, leading to the 'water-gap' opening. We argue that the moisture content of the seeds and its interaction with biochemical compounds are a possible explanation for why only a proportion of PY seeds become permeable to water each year. Nonetheless, empirical investigations must validate these notions.

Insights into the Mechanism of Tryptophan Fluorescence Quenching due to Synthetic Crowding Agents: A Combined Experimental and Computational Study.

Intrinsic tryptophan fluorescence spectroscopy is an important tool for examining the effects of molecular crowding and confinement on the structure, dynamics, and function of proteins. Synthetic crowders such as dextran, ficoll, polyethylene glycols, polyvinylpyrrolidone, and their respective monomers are used to mimic crowded intracellular environments. Interactions of these synthetic crowders with tryptophan and the subsequent impact on its fluorescence properties are therefore critically important for understanding the possible interference created by these crowders. In the present study, the effects of polymer and monomer crowders on tryptophan fluorescence were assessed by using experimental and computational approaches. The results of this study demonstrated that both polymer and monomer crowders have an impact on the tryptophan fluorescence intensity; however, the molecular mechanisms of quenching were different. Using Stern-Volmer plots and a temperature variation study, a physical basis for the quenching mechanism of commonly used synthetic crowders was established. The quenching of free tryptophan was found to involve static, dynamic, and sphere-of-action mechanisms. In parallel, computational studies employing Kohn-Sham density functional theory provided a deeper insight into the effects of intermolecular interactions and solvation, resulting in differing quenching modes for these crowders. Taken together, the study offers new physical insights into the quenching mechanisms of some commonly used monomer and polymer synthetic crowders.

A Comprehensive Literature Review of Digital Health Interventions in the Treatment of Substance Use Disorder With Special Focus on Mobile Applications.

COVID-19 quarantine showed an increase in opioid-related deaths partially due to the limited capacity of clinics and treatment centers. Digital health interventions (DHIs) such as telehealth have improved access to treatment, reduced psychosocial barriers, and helped patients with substance use disorder (SUD). An in-depth literature review was conducted to gauge the efficacy and usefulness of DHIs on substance use disorder. PubMed was used with string search terms to identify studies analyzing telehealth for substance use disorders. Studies were eligible and selected if they used health interventions (HIs) and reported outcomes on the efficacy of DHIs, benefits of DHIs, and limitations of DHIs. The Agency of Healthcare Research and Quality (AHRQ) was used to analyze the impact of DHIs on SUD. Lastly, Apple's App Store was used to identify the current DHI available. The analysis indicated that mobile phone apps were the most appropriate sources to use for patients with substance use disorders. The search also found 36 mobile applications available on the market for patients, containing mainly pain medication diaries and trackers. The study did not find any apps for clinical usage that met the standards necessary for adequate healthcare in the opioid crisis, largely due to a lack of clinician involvement in using applications. Developing adequate DHIs has the potential to improve outcomes in patients with SUD and aid in recovery time. The research concluded that physicians looking to develop DHIs should take into consideration the mode of delivery of DHI, the aim to produce specific health outcomes as opposed to multiple outcomes, and clinician involvement in DHI development. DHIs can become a vital tool for medical professionals, especially during the COVID-19 crisis, as the use of healthcare technology has limited in-person contact, maintained current doctor-patient relationships, and allowed for contact tracing of the disease.

The high optical brightness of the BlueWalker 3 satellite.

Large constellations of bright artificial satellites in low Earth orbit pose significant challenges to ground-based astronomy1. Current orbiting constellation satellites have brightnesses between apparent magnitudes 4 and 6, whereas in the near-infrared Ks band, they can reach magnitude 2 (ref. 2). Satellite operators, astronomers and other users of the night sky are working on brightness mitigation strategies3,4. Radio emissions induce further potential risk to ground-based radio telescopes that also need to be evaluated. Here we report the outcome of an international optical observation campaign of a prototype constellation satellite, AST SpaceMobile's BlueWalker 3. BlueWalker 3 features a 64.3 m2 phased-array antenna as well as a launch vehicle adaptor (LVA)5. The peak brightness of the satellite reached an apparent magnitude of 0.4. This made the new satellite one of the brightest objects in the night sky. Additionally, the LVA reached an apparent V-band magnitude of 5.5, four times brighter than the current International Astronomical Union recommendation of magnitude 7 (refs. 3,6); it jettisoned on 10 November 2022 (Universal Time), and its orbital ephemeris was not publicly released until 4 days later. The expected build-out of constellations with hundreds of thousands of new bright objects1 will make active satellite tracking and avoidance strategies a necessity for ground-based telescopes.

Isolated corona current monitoring using a compensated light-emitting diode as an unpowered sensor.

Measurement of the emission current at a high voltage is necessary in monitoring ion production from a corona source, to provide independent confirmation of operation. The wide common mode range required is usually obtained through an isolated system, which requires isolated power to operate, adding complexity and volume. Passing the current through a light-emitting diode (LED) provides an alternative measurement method as the LED's brightness can be used to signal the current's magnitude. The forward voltage loss across the LED is negligible compared with the emitter voltage. Selection of a discrete LED for this task rather than using one within a standard integrated optocoupler package improves the low current sensitivity by two orders of magnitude. A high efficiency discrete infrared LED-photodiode pair is demonstrated to provide measurements of corona currents between 0.2 and 20 µA using a second LED-photodiode pair for analog linearity compensation. The inherent simplicity is well suited to new applications of ion emission in propulsion and weather modification.

Progressive drought alters the root exudate metabolome and differentially activates metabolic pathways in cotton (Gossypium hirsutum).

Root exudates comprise various primary and secondary metabolites that are responsive to plant stressors, including drought. As increasing drought episodes are predicted with climate change, identifying shifts in the metabolome profile of drought-induced root exudation is necessary to understand the molecular interactions that govern the relationships between plants, microbiomes, and the environment, which will ultimately aid in developing strategies for sustainable agriculture management. This study utilized an aeroponic system to simulate progressive drought and recovery while non-destructively collecting cotton (Gossypium hirsutum) root exudates. The molecular composition of the collected root exudates was characterized by untargeted metabolomics using Fourier-Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS) and mapped to the Kyoto Encyclopedia of Genes and Genomes (KEGG) databases. Over 700 unique drought-induced metabolites were identified throughout the water-deficit phase. Potential KEGG pathways and KEGG modules associated with the biosynthesis of flavonoid compounds, plant hormones (abscisic acid and jasmonic acid), and other secondary metabolites were highly induced under severe drought, but not at the wilting point. Additionally, the associated precursors of these metabolites, such as amino acids (phenylalanine and tyrosine), phenylpropanoids, and carotenoids, were also mapped. The potential biochemical transformations were further calculated using the data generated by FT-ICR MS. Under severe drought stress, the highest number of potential biochemical transformations, including methylation, ethyl addition, and oxidation/hydroxylation, were identified, many of which are known reactions in some of the mapped pathways. With the application of FT-ICR MS, we revealed the dynamics of drought-induced secondary metabolites in root exudates in response to drought, providing valuable information for drought-tolerance strategies in cotton.

Dynamics of an incoherent feedforward loop drive ERK-dependent pattern formation in the early Drosophila embryo.

Positional information in development often manifests as stripes of gene expression, but how stripes form remains incompletely understood. Here, we use optogenetics and live-cell biosensors to investigate the posterior brachyenteron (byn) stripe in early Drosophila embryos. This stripe depends on interpretation of an upstream ERK activity gradient and the expression of two target genes, tailless (tll) and huckebein (hkb), that exert antagonistic control over byn. We find that high or low doses of ERK signaling produce transient or sustained byn expression, respectively. Although tll transcription is always rapidly induced, hkb converts graded ERK inputs into a variable time delay. Nuclei thus interpret ERK amplitude through the relative timing of tll and hkb transcription. Antagonistic regulatory paths acting on different timescales are hallmarks of an incoherent feedforward loop, which is sufficient to explain byn dynamics and adds temporal complexity to the steady-state model of byn stripe formation. We further show that 'blurring' of an all-or-none stimulus through intracellular diffusion non-locally produces a byn stripe. Overall, we provide a blueprint for using optogenetics to dissect developmental signal interpretation in space and time.

Efficacy of green infrastructure in reducing exposure to local, traffic-related sources of airborne particulate matter (PM).

One aim of roadside green infrastructure (GI) is to mitigate exposure to local, traffic-generated pollutants. Here, we determine the efficacy of roadside GI in improving local air quality through the deposition and/or dispersion of airborne particulate matter (PM). PM was collected on both pumped air filters and on the leaves of a recently installed 'tredge' (trees managed as a head-high hedge) at an open road environment next to a primary school in Manchester, U.K. The magnetic properties of PM deposited on leaves and filters (size fractions PM10 and PM2.5) were deduced from hysteresis loops, first-order reversal curves (FORCs), and low-temperature remanence measurements. These were complemented with electron microscopy to identify changes in magnetic PM concentration downwind of the tredge/GI. We show that the tredge is permeable to airflow using a simple CO2 tracer experiment; hence, it allows interception and subsequent deposition of PM on its leaves. Magnetic loadings per m3 of air from filters (PM10 saturation magnetisation, Ms, at 5 K) were reduced by 40 % behind the tredge and a further 63 % in the playground; a total reduction of 78 % compared to roadside air. For the PM2.5 fraction, the reduction in magnetic loading behind the tredge was remarkable (82 %), reflecting efficient diffusional capture of sub-5 nm Fe-oxide particles by the tredge. Some direct mixing of roadside and playground air occurs at the back of the playground, caused by air flow over, and/or through gaps in, the slowly-permeable tredge. The magnetic loading on tredge leaves increased over successive days, capturing ~23 % of local, traffic-derived PM10. Using a heuristic two-dimensional turbulent mixing model, we assess the limited dispersion of PM < 22.5 µm induced by eddies in the tredge wake. This study demonstrates that PM deposition on leaves reduces exposure significantly in this school playground setting; hence, providing a cost-effective mitigation strategy.

Clinical Outcomes Following Percutaneous Ankle Fusion With Bone Graft Substitute.

Background: Percutaneous ankle fusion is an emerging technique with minimal published outcome data. The goal of the present study is to retrospectively review clinical and radiographic outcomes following percutaneous ankle fusion and provide technique tips to perform percutaneous ankle fusion. Methods: Patients >18 years of age, treated by a single surgeon, from February 2018 to June 2021, who underwent primary isolated percutaneous ankle fusion supplemented with platelet-derived growth factor B (rhPDGF-BB) and beta-tricalcium phosphate, with at least 1-year follow-up were included. Surgical technique consisted of percutaneous ankle preparation followed by fixation with 3 headless compression screws. Pre- and postoperative visual analog scale (VAS) and Foot Function Index (FFI) were compared using paired t tests. Fusion was assessed radiographically by the surgeon on postoperative radiographs and computed tomography (CT) at 3 months postoperatively. Results: Twenty-seven consecutive adult patients were included in the study. Mean follow-up was 21 months. Mean age was 59.8 years. Mean preoperative and postoperative VAS scores were 7.4 and 0.2, respectively (P < .01). Mean preoperative FFI pain domain, disability domain, activity restriction domain, and total score were 20.9, 16.7, 18.5, and 56.4, respectively. Mean postoperative FFI pain domain, disability domain, activity restriction domain, and total score were 4.3, 4.7, 6.7, and 15.8, respectively (P < .01). Fusion was achieved in 26 of 27 patients (96.3%) at 3 months. Four patients (14.8%) had complications. Conclusion: We found in this cohort with surgery performed by a surgeon highly experienced in minimally invasive surgery that percutaneous ankle fusion augmented with a bone graft supplement achieved a high rate of fusion (96.3%) and a significant improvement in pain and function postoperatively while associated with minimal complications. Level of Evidence: Level IV, case series.

Highlights from the Second Choosing Wisely Africa conference: a roadmap to value-based cancer care in East Africa (9-10 February 2023, Dar es Salaam, Tanzania).

The ecancer Choosing Wisely conference was held for the second time in Africa in Dar es Salaam, Tanzania, from the 9th to 10th of February 2023. ecancer in collaboration with the Tanzania Oncology Society organised this conference which was attended by more than 150 local and international delegates. During the 2 days of the conference, more than ten speakers from different specialties in the field of oncology gave insights into Choosing Wisely in oncology. Topics from all fields linked to cancer care such as radiation oncology, medical oncology, prevention, oncological surgery, palliative care, patient advocacy, pathology, radiology, clinical trials, research and training were presented to share and bring awareness to professionals in oncology, on how to choose wisely in their approach to their daily practice, based on the available resources, while trying to offer the maximum benefit to the patient. This report, therefore, shares the highlights of this conference.

Understanding the Molecular Basis for Homodimer Formation of the Pneumococcal Endolysin Cpl-1.

The rise of multi-drug-resistant bacteria that cannot be treated with traditional antibiotics has prompted the search for alternatives to combat bacterial infections. Endolysins, which are bacteriophage-derived peptidoglycan hydrolases, are attractive tools in this fight. Several studies have already demonstrated the efficacy of endolysins in targeting bacterial infections. Endolysins encoded by bacteriophages that infect Gram-positive bacteria typically possess an N-terminal catalytic domain and a C-terminal cell-wall binding domain (CWBD). In this study, we have uncovered the molecular mechanisms that underlie formation of a homodimer of Cpl-1, an endolysin that targets Streptococcus pneumoniae. Here, we use site-directed mutagenesis, analytical size exclusion chromatography, and analytical ultracentrifugation to disprove a previous suggestion that three residues at the N-terminus of the CWBD are involved in the formation of a Cpl-1 dimer in the presence of choline in solution. We conclusively show that the C-terminal tail region of Cpl-1 is involved in formation of the dimer. Alanine scanning mutagenesis generated various tail mutant constructs that allowed identification of key residues that mediate Cpl-1 dimer formation. Finally, our results allowed identification of a consensus sequence (FxxEPDGLIT) required for choline-dependent dimer formation─a sequence that occurs frequently in pneumococcal autolysins and endolysins. These findings shed light on the mechanisms of Cpl-1 and related enzymes and can be used to inform future engineering efforts for their therapeutic development against S. pneumoniae.

Polyethylene Glycol 20k. Does It Fluoresce?

Polyethylene glycol (PEG) is a polyether compound commonly used in biological research and medicine because it is biologically inert. This simple polymer exists in variable chain lengths (and molecular weights). As they are devoid of any contiguous π-system, PEGs are expected to lack fluorescence properties. However, recent studies suggested the occurrence of fluorescence properties in non-traditional fluorophores like PEGs. Herein, a thorough investigation has been conducted to explore if PEG 20k fluoresces. Results of this combined experimental and computational study suggested that although PEG 20k could exhibit "through-space" delocalization of lone pairs of electrons in aggregates/clusters, formed via intermolecular and intramolecular interactions, the actual contributor of fluorescence between 300 and 400 nm is the stabilizer molecule, i.e., 3-tert-butyl-4-hydroxyanisole present in the commercially available PEG 20k. Therefore, the reported fluorescence properties of PEG should be taken with a grain of salt, warranting further investigation.

Supraorbital vs pterional keyhole for anterior circulation aneurysms: A systematic review and meta-analysis.

Background: The supraorbital approach is a modification of the traditional pterional approach, and it offers the benefits of a shorter skin incision and a smaller craniotomy than the pterional approach. The purpose of this systemic review study was to compare the two surgical approaches for raptured and unruptured anterior cerebral circulation aneurysms. Methods: We searched PubMed, EMBASE, Cochrane Library, SCOPUS, and MEDLINE, up to August 2021, for published studies on the supraorbital vs pterional keyhole approach for anterior cerebral circulation aneurysms, and reviewers performed a brief qualitative descriptive analysis of both approaches. Results: Fourteen eligible studies were included in this systemic review. Results indicated that the supraorbital approach for anterior cerebral circulation aneurysms had fewer ischemic events compared to pterional approach. However, no significant difference between both groups in terms of complications such as intraoperative aneurysm rupture, brain hematoma, and postoperative infections for ruptured aneurysms. Conclusion: The meta-analysis suggests that the supraorbital method for clipping anterior cerebral circulation aneurysms might be a viable alternative to the traditional pterional method as the supraorbital group had decreased ischemic events compared to the pterional group, however, the associated difficulties in utilizing this approach among ruptured aneurysms with cerebral oedema and midline shifts further needs to be understood.

Dynamics of an incoherent feedforward loop drive ERK-dependent pattern formation in the early Drosophila embryo.

Positional information in developing tissues often takes the form of stripes of gene expression that mark the boundaries of a particular cell type or morphogenetic process. How stripes form is still in many cases poorly understood. Here we use optogenetics and live-cell biosensors to investigate one such pattern: the posterior stripe of brachyenteron (byn) expression in the early Drosophila embryo. This byn stripe depends on interpretation of an upstream signal - a gradient of ERK kinase activity - and the expression of two target genes tailless (tll) and huckebein (hkb) that exert antagonistic control over byn . We find that high or low doses of ERK signaling produce either transient or sustained byn expression, respectively. These ERK stimuli also regulate tll and hkb expression with distinct dynamics: tll transcription is rapidly induced under both low and high stimuli, whereas hkb transcription converts graded ERK inputs into an output switch with a variable time delay. Antagonistic regulatory paths acting on different timescales are hallmarks of an incoherent feedforward loop architecture, which is sufficient to explain transient or sustained byn dynamics and adds temporal complexity to the steady-state model of byn stripe formation. We further show that an all-or-none stimulus can be 'blurred' through intracellular diffusion to non-locally produce a stripe of byn gene expression. Overall, our study provides a blueprint for using optogenetic inputs to dissect developmental signal interpretation in space and time.

Routine ultrasound for suspected appendicitis in children: a single-centre retrospective cohort study.

INTRODUCTION: Appendicitis continues to be a common surgical emergency in children, but its diagnosis remains challenging. Use of diagnostic imaging to confirm appendicitis has gained popularity in some countries because it is associated with lower negative appendicectomy rates. This study reports our centre's experience of adopting routine ultrasound for the investigation of suspected appendicitis in children. METHODS: A single-centre retrospective cohort study was performed investigating all children aged 5-16 years admitted under surgeons with suspected appendicitis, in January-December 2019. Primary outcomes were the rate of ultrasound use, its accuracy in diagnosing/excluding appendicitis and negative appendicectomy rate. Other outcomes were treatment received, length of stay and complications. RESULTS: The majority of the 193 children with suspected appendicitis underwent a diagnostic ultrasound (87.5%). Ultrasound was highly sensitive (0.90, 95% confidence interval (CI) 0.81-0.96) and specific (1.0, 95% CI 0.96-1.0) for appendicitis in this study. Negative appendicectomy rate was extremely low (1.4%). Laparoscopic appendicectomy was the preferred management (75/86), with one case started open and no conversions to open. A minority of cases of simple appendicitis (10/86) were treated primarily with antibiotics. Rates of complex appendicitis and postoperative complications were similar to other studies. CONCLUSION: Ultrasound can be highly sensitive and specific for appendicitis. Its routine use to confirm appendicitis prior to surgery is associated with a low negative appendicectomy rate. This is a major change in practice for a general surgical unit in the United Kingdom.

A two-ward acute care hospital outbreak of SARS-CoV-2 delta variant including a point-source outbreak associated with the use of a mobile vital signs cart and sub-optimal doffing of personal protective equipment.

BACKGROUND: The arrival of the Delta variant of SARS-CoV-2 was associated with increased transmissibility and illness of greater severity. Reports of nosocomial outbreaks of Delta variant COVID-19 in acute care hospitals have been described but control measures varied widely. AIM: Epidemiological investigation of a linked two-ward COVID-19 Delta variant outbreak was conducted to elucidate its source, risk factors, and control measures. METHODS: Investigations included epidemiologic analysis, detailed case review serial SARS-CoV-2 reverse transcriptase-polymerase chain reaction (RT-PCR) testing of patients and healthcare workers (HCWs), viral culture, environmental swabbing, HCW-unaware personal protective equipment (PPE) audits, ventilation assessments, and the use of whole genome sequencing (WGS). FINDINGS: This linked two-ward outbreak resulted in 17 patient and 12 HCW cases, despite an 83% vaccination rate. In this setting, suboptimal adherence and compliance to PPE protocols, suboptimal hand hygiene, multi-bedded rooms, and a contaminated vital signs cart with potential fomite or spread via the hands of HCWs were identified as significant risk factors for nosocomial COVID-19 infection. Sudden onset of symptoms, within 72 h, was observed in 79% of all Ward 2 patients, and 93% of all cases (patients and HCWs) on Ward 2 occurred within one incubation period, consistent with a point-source outbreak. RT-PCR assays showed low cycle threshold (CT) values, indicating high viral load from environmental swabs including the vital signs cart. WGS results with ≤3 SNP differences between specimens were observed. CONCLUSION: Outbreaks on both wards settled rapidly, within 3 weeks, using a `back-to-basics' approach without extraordinary measures or changes to standard PPE requirements. Strict adherence to recommended PPE, hand hygiene, education, co-operation from HCWs, including testing and interviews, and additional measures such as limiting movement of patients and staff temporarily were all deemed to have contributed to prompt resolution of the outbreak.