Measurement of stimulated Hawking emission in an analogue system

There is a mathematical analogy between the propagation of fields in a general relativistic space-time and long (shallow water) surface waves on moving water. Hawking argued that black holes emit thermal radiation via a quantum spontaneous emission. Similar arguments predict the same effect near wave horizons in fluid flow. By placing a streamlined obstacle into an open channel flow we create a region of high velocity over the obstacle that can include wave horizons. Long waves propagating upstream towards this region are blocked and converted into short (deep water) waves. This is the analogue of the stimulated emission by a white hole (the time inverse of a black hole), and our measurements of the amplitudes of the converted waves demonstrate the thermal nature of the conversion process for this system. Given the close relationship between stimulated and spontaneous emission, our findings attest to the generality of the Hawking process.Comment: 7 pages, 5 figures. This version corrects a processing error in the final graph 5b which multiplied the vertical axis by 2. The graph, and the data used from it, have been corrected. Some minor typos have also been corrected. This version also uses TeX rather than Wor

The Stereotypic Response of the Pulmonary Vasculature to Respiratory Viral Infections: Findings in Mouse Models of SARS-CoV-2, Influenza A and Gammaherpesvirus Infections

The respiratory system is the main target of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the cause of coronavirus disease 19 (COVID-19) where acute respiratory distress syndrome is considered the leading cause of death. Changes in pulmonary blood vessels, among which an endothelialitis/endotheliitis has been particularly emphasized, have been suggested to play a central role in the development of acute lung injury. Similar vascular changes are also observed in animal models of COVID-19. The present study aimed to determine whether the latter are specific for SARS-CoV-2 infection, investigating the vascular response in the lungs of mice infected with SARS-CoV-2 and other respiratory viruses (influenza A and murine gammaherpesvirus) by in situ approaches (histology, immunohistology, morphometry) combined with RNA sequencing and bioinformatic analysis. Non-selective recruitment of monocytes and T and B cells from larger muscular veins and arteries was observed with all viruses, matched by a comparable transcriptional response. There was no evidence of endothelial cell infection in any of the models. Both the morphological investigation and the transcriptomics approach support the interpretation that the lung vasculature in mice mounts a stereotypic response to alveolar and respiratory epithelial damage. This may have implications for the treatment and management of respiratory disease in humans

Spore forming bacteria infections and people who inject drugs: Implications for harm reduction.

BACKGROUND: There is no research on public health interventions that alert people who inject drugs (PWID) to clusters/outbreaks of severe bacterial infections. In Scotland, during the botulism cluster/outbreak of Dec 2014-July 2015 harm reduction (HR) messages detailed on a postcard (Botulism Postcard) were distributed to PWID between Feb-April 2015. We examined the impact of the Botulism Postcard on cluster/outbreak awareness, healthcare seeking and HR behaviours among PWID; and their views on such clusters/outbreaks. METHODS: The Botulism Postcard questionnaire survey was undertaken with 288 PWID recruited in Greater Glasgow and Clyde between May-August 2015. Multivariate logistic regression was undertaken. Between Oct 2015-January 2016 22 in-depth interviews were conducted with PWID in Glasgow and Edinburgh, these underwent thematic analysis. RESULTS: 38% (108/284) had never seen the postcard, 14% (40/284) had only seen it, 34% (98/284) read but not discussed it and 13% (38/284) had discussed it with service staff. Cluster/outbreak awareness was higher among those who had read (adjusted odds ratio (aOR) = 5.374, CI 2.394-11.349, p < 0.001) or discussed the postcard (aOR = 25.114, CI 3.188-190.550, p < 0.001); and symptom awareness was higher among those who had read (aOR = 2.664, CI 1.322-4.890, p < 0.001) or discussed the postcard (aOR = 6.707, CI 2.744 16.252, p < 0.001) than among those who had never seen it. The odds of introducing HR was higher among those who had discussed the postcard (AOR = 3.304 CI 1.425 7.660, p < 0.01) than those who had only read it. PWID learnt about clusters/outbreaks from several sources and despite concerns they continued to inject during such events. CONCLUSION: More widespread exposure to the Botulism Postcard during the outbreak/cluster was needed. The Botulism Postcard distributed to PWID may raise awareness of such events, the symptoms, and may encourage HR particularly when used as a tool by frontline staff to initiate discussion. Acknowledging that people continue to inject during clusters/outbreaks of such infections necessitates a pragmatic HR approach

The P323L Substitution in the SARS-CoV-2 Polymerase (NSP12) Confers a Selective Advantage During Infection

BACKGROUND: The mutational landscape of SARS-CoV-2 varies at the dominant viral genome sequence and minor genomic variant population. During the COVID-19 pandemic, an early substitution in the genome was the D614G change in the spike protein, associated with an increase in transmissibility. Genomes with D614G are accompanied by a P323L substitution in the viral polymerase (NSP12). However, P323L is not thought to be under strong selective pressure. RESULTS: Investigation of P323L/D614G substitutions in the population shows rapid emergence during the containment phase and early surge phase during the first wave. These substitutions emerge from minor genomic variants which become dominant viral genome sequence. This is investigated in vivo and in vitro using SARS-CoV-2 with P323 and D614 in the dominant genome sequence and L323 and G614 in the minor variant population. During infection, there is rapid selection of L323 into the dominant viral genome sequence but not G614. Reverse genetics is used to create two viruses (either P323 or L323) with the same genetic background. L323 shows greater abundance of viral RNA and proteins and a smaller plaque morphology than P323. CONCLUSIONS: These data suggest that P323L is an important contribution in the emergence of variants with transmission advantages. Sequence analysis of viral populations suggests it may be possible to predict the emergence of a new variant based on tracking the frequency of minor variant genomes. The ability to predict an emerging variant of SARS-CoV-2 in the global landscape may aid in the evaluation of medical countermeasures and non-pharmaceutical interventions

The prognostic value of multivoxel magnetic resonance spectroscopy determined metabolite levels in white and grey matter brain tissue for adverse outcome in term newborns following perinatal asphyxia

Magnetic resonance spectroscopy can identify brain metabolic changes in perinatal asphyxia by providing ratios of metabolites, such as choline (Cho), creatine (Cr), N-acetyl aspartate (NAA) and lactate (Lact) [Cho/Cr, Lact/NAA, etc.]. The purpose of this study was to quantify the separate white and grey matter metabolites in a slab cranial to the ventricles and relate these to the outcome. A standard 2D-chemical shift imaging protocol was used for measuring a transverse volume of interest located cranial to the ventricles allowing for direct comparison of the metabolites in white and grey matter brain tissue in 24 term asphyxiated newborns aged 3 to 16 days. Cho, NAA and Lact showed significant differences between four subgroups of asphyxiated infants with more and less favourable outcomes. High levels of Cho and Lact in the grey matter differentiated non-survivors from survivors (P = 0.003 and P = 0.017, respectively). In perinatal asphyxia the levels of Cho, NAA and Lact in both white and grey matter brain tissue are affected. The levels of Cho and Lact measured in the grey matter are the most indicative of survival. It is therefore advised to include grey matter brain tissue in the region of interest examined by multivoxel MR spectroscopy. aEuro cent Magnetic resonance spectroscopy can identify brain metabolic changes in perinatal asphyxia. aEuro cent Choline and lactate levels in grey matter seem the best indicators of survival. aEuro cent Both grey and white matter should be examined during spectroscopy for perinatal asphyxia

Enrichment of SARS-CoV-2 sequence from nasopharyngeal swabs whilst identifying the nasal microbiome

Simultaneously characterising the genomic information of coronaviruses and the underlying nasal microbiome from a single clinical sample would help characterise infection and disease. Metatranscriptomic approaches can be used to sequence SARS-CoV-2 (and other coronaviruses) and identify mRNAs associated with active transcription in the nasal microbiome. However, given the large sequence background, unenriched metatranscriptomic approaches often do not sequence SARS-CoV-2 to sufficient read and coverage depth to obtain a consensus genome, especially with moderate and low viral loads from clinical samples. In this study, various enrichment methods were assessed to detect SARS-CoV-2, identify lineages and define the nasal microbiome. The methods were underpinned by Oxford Nanopore long-read sequencing and variations of sequence independent single primer amplification (SISPA). The utility of the method(s) was also validated on samples from patients infected seasonal coronaviruses. The feasibility of profiling the nasal microbiome using these enrichment methods was explored. The findings shed light on the performance of different enrichment strategies and their applicability in characterising the composition of the nasal microbiome

Patterns of neonatal hypoxic–ischaemic brain injury

Enormous progress has been made in assessing the neonatal brain, using magnetic resonance imaging (MRI). In this review, we will describe the use of MRI and proton magnetic resonance spectroscopy in detecting different patterns of brain injury in (full-term) human neonates following hypoxic–ischaemic brain injury and indicate the relevance of these findings in predicting neurodevelopmental outcome