79 research outputs found
A novel wideband dynamic directional indoor channel model based on a Markov process
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Novel 3D Geometry-Based Stochastic Models for Non-Isotropic MIMO Vehicle-to-Vehicle Channels
This paper proposes a novel three-dimensional (3D) theoretical regular-shaped
geometry-based stochastic model (RS-GBSM) and the corresponding
sum-of-sinusoids (SoS) simulation model for non-isotropic multiple-input
multiple-output (MIMO) vehicle-to-vehicle (V2V) Ricean fading channels. The
proposed RS-GBSM, combining line-of-sight (LoS) components, a two-sphere model,
and an elliptic-cylinder model, has the ability to study the impact of the
vehicular traffic density (VTD) on channel statistics, and jointly considers
the azimuth and elevation angles by using the von Mises Fisher distribution.
Moreover, a novel parameter computation method is proposed for jointly
calculating the azimuth and elevation angles in the SoS channel simulator.
Based on the proposed 3D theoretical RS-GBSM and its SoS simulation model,
statistical properties are derived and thoroughly investigated. The impact of
the elevation angle in the 3D model on key statistical properties is
investigated by comparing with those of the corresponding two-dimensional (2D)
model. It is demonstrated that the 3D model is more accurate to characterize
real V2V channels, in particular for pico cell scenarios. Finally, close
agreement is achieved between the theoretical model, SoS simulation model, and
simulation results, demonstrating the utility of the proposed models
Towards a Tailored Sensor Network for Fire Emergency Monitoring in Large Buildings
Modern fire emergency systems are slowly moving from the traditional data-logging systems to a heterogeneous and dense network of wired/wireless sensors that can give a more complete view of the phenomenon. When the density of the sensors and/or the transmission rate start growing, standard and widely used communication protocols suffer from degradation in their performance, mostly due to the presence of simultaneous transmissions. Rather than proposing a new protocol that performs better than the standard ones in a set of network scenarios, this paper has a different aim. It attempts to draw conclusions from the nature of the sensed data itself, so that important spatial and/or temporal correlations can be revealed and, consequently, utilised for the future design of an indoor fire emergency-tailored protocol
On analytical derivations of the condition number distributions of dual non-central Wishart matrices
The 2021 WHO catalogue of Mycobacterium tuberculosis complex mutations associated with drug resistance: a genotypic analysis.
Background: Molecular diagnostics are considered the most promising route to achievement of rapid, universal drug susceptibility testing for Mycobacterium tuberculosis complex (MTBC). We aimed to generate a WHO-endorsed catalogue of mutations to serve as a global standard for interpreting molecular information for drug resistance prediction. Methods: In this systematic analysis, we used a candidate gene approach to identify mutations associated with resistance or consistent with susceptibility for 13 WHO-endorsed antituberculosis drugs. We collected existing worldwide MTBC whole-genome sequencing data and phenotypic data from academic groups and consortia, reference laboratories, public health organisations, and published literature. We categorised phenotypes as follows: methods and critical concentrations currently endorsed by WHO (category 1); critical concentrations previously endorsed by WHO for those methods (category 2); methods or critical concentrations not currently endorsed by WHO (category 3). For each mutation, we used a contingency table of binary phenotypes and presence or absence of the mutation to compute positive predictive value, and we used Fisher's exact tests to generate odds ratios and Benjamini-Hochberg corrected p values. Mutations were graded as associated with resistance if present in at least five isolates, if the odds ratio was more than 1 with a statistically significant corrected p value, and if the lower bound of the 95% CI on the positive predictive value for phenotypic resistance was greater than 25%. A series of expert rules were applied for final confidence grading of each mutation. Findings: We analysed 41 137 MTBC isolates with phenotypic and whole-genome sequencing data from 45 countries. 38 215 MTBC isolates passed quality control steps and were included in the final analysis. 15 667 associations were computed for 13 211 unique mutations linked to one or more drugs. 1149 (7·3%) of 15 667 mutations were classified as associated with phenotypic resistance and 107 (0·7%) were deemed consistent with susceptibility. For rifampicin, isoniazid, ethambutol, fluoroquinolones, and streptomycin, the mutations' pooled sensitivity was more than 80%. Specificity was over 95% for all drugs except ethionamide (91·4%), moxifloxacin (91·6%) and ethambutol (93·3%). Only two resistance mutations were identified for bedaquiline, delamanid, clofazimine, and linezolid as prevalence of phenotypic resistance was low for these drugs. Interpretation: We present the first WHO-endorsed catalogue of molecular targets for MTBC drug susceptibility testing, which is intended to provide a global standard for resistance interpretation. The existence of this catalogue should encourage the implementation of molecular diagnostics by national tuberculosis programmes. Funding: Unitaid, Wellcome Trust, UK Medical Research Council, and Bill and Melinda Gates Foundation
Dimethyl fumarate in patients admitted to hospital with COVID-19 (RECOVERY): a randomised, controlled, open-label, platform trial
Dimethyl fumarate (DMF) inhibits inflammasome-mediated inflammation and has been proposed as a treatment for patients hospitalised with COVID-19. This randomised, controlled, open-label platform trial (Randomised Evaluation of COVID-19 Therapy [RECOVERY]), is assessing multiple treatments in patients hospitalised for COVID-19 (NCT04381936, ISRCTN50189673). In this assessment of DMF performed at 27 UK hospitals, adults were randomly allocated (1:1) to either usual standard of care alone or usual standard of care plus DMF. The primary outcome was clinical status on day 5 measured on a seven-point ordinal scale. Secondary outcomes were time to sustained improvement in clinical status, time to discharge, day 5 peripheral blood oxygenation, day 5 C-reactive protein, and improvement in day 10 clinical status. Between 2 March 2021 and 18 November 2021, 713 patients were enroled in the DMF evaluation, of whom 356 were randomly allocated to receive usual care plus DMF, and 357 to usual care alone. 95% of patients received corticosteroids as part of routine care. There was no evidence of a beneficial effect of DMF on clinical status at day 5 (common odds ratio of unfavourable outcome 1.12; 95% CI 0.86-1.47; p = 0.40). There was no significant effect of DMF on any secondary outcome
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