5,388 research outputs found
Epidemiological and genomic landscape of antimicrobial resistance in Malawi
No full textAntimicrobial resistance (AMR) is a global public health problem, which presents a huge threat to the treatment of all forms of bacterial infections. A wide range of bacterial pathogens across the globe are increasingly developing resistance to multiple classes of antimicrobial agents rendering the agents concerned ineffective for the treatment of infections. Bloodstream infection (BSI) and other bacterial infections in sub-Saharan Africa (SSA) and Malawi in particular, are a common cause of morbidity and mortality.
Few facilities in SSA however, are able to conduct long-term surveillance and as such the full burden of drug resistant infection (DRI) remain largely unknown across the region. In this thesis, blood cultures routinely taken from adult and paediatric medical patients admitted to Queen Elizabeth Central Hospital (QECH) in Blantyre, Malawi between 1998 and 2016 were analysed to describe trends in BSI and AMR.
The analysis revealed a significant decline of BSI in all major pathogens except S. Typhi. However, the majority of isolates were resistant to the Malawian first-line antimicrobial agents (ampicillin, cotrimoxazole and chloramphenicol). Resistance to all the first line antimicrobial agents was more common in Gram-negative pathogens than Gram-positive pathogens. Non-Salmonellae Enterobacteriaceae that produced extended spectrum beta-lactamase (ESBL) and were fluoroquinolone-resistant were detected, and the proportions of these isolates rose significantly during the surveillance. In contrast, a majority of common Gram-positive pathogens remain susceptible to either penicillin or chloramphenicol. Methicillin resistant S. aureus was first reported in 1998 but became regularly detected in the later years of the surveillance.
The analysis of blood culture isolates identified E. coli as one of the common causes of BSI in Blantyre, and the proportion of these isolates that were ESBL producers increased over time. Globally, efforts to treat E. coli infections are increasingly being compromised by the rapid, global spread of ESBL-producing E. coli. In this thesis, a whole genome sequencing (WGS) study was carried out to investigate the genetic population structure and molecular determinants of AMR in E. coli isolates from Malawi.
Whole genomes of clinical E. coli isolates from patients admitted to QECH were sequenced and analysed using phylogenetic methods and comparative genomics. It was revealed that the E. coli population in Malawi is highly diverse with isolates belonging to five phylogroups, corresponding to five isolate sequence clusters (SCs) that contained over forty sequence types (STs). A unique sub-lineage of ST131 was identified that was distinct from previously defined sub-lineages of this globally disseminated ST. The most common ESBL gene was blaCT X-M-15. Unlike in other settings where presence of the blaCT X-M-15 gene was strongly linked to ST131, here the gene was not lineage-specific suggesting a distinct genomic landscape of ESBL-producing E. coli in Malawi.
This thesis also identified Klebsiella spp. isolates as a common cause of BSI in Blantyre, and an increasing proportion of ESBL-producing and fluoroquinolone resistant isolates were identified. The molecular mechanisms and clones of K. pneumoniae associated with ESBL production and fluoroquinolone resistance were yet to be explored in Malawi. Here, a number of K. pneumoniae isolates were selected for WGS, and placed in a global context by comparison with previously sequenced K. pneumoniae isolates from multiple locations outside SSA, in order to identify the molecular determinants of AMR and determine their relationship with K. pneumoniae population structure.
Genomic analysis revealed three main lineages of K. pneumoniae, which corresponded to the previously defined KpI, KpII and KpIII lineages. All three lineages exhibited high genetic diversity. Further phylogenetic analysis revealed a sub-lineage of KpI to be a major cause of CA infections in Malawi. The sub-lineage included the clonally related ST14 and ST15 of K. pneumoniae which cause hospital acquired infection in multiple settings across the globe, A large pool of AMR genes, was identified in the genomes of the Malawian isolates, including multiple ESBL and qnr genes. Plasmid-encoded CTX-M-15 was the most common type of ESBL that was identified. In common with E. coli from Malawi, AMR was not restricted to a particular clade of K. pneumoniae. These findings suggest that dissemination of AMR in the K. pneumoniae population in Malawi was either due to a combination of horizontal gene transfer and clonal expansion, or horizontal gene transfer alone.
In conclusion, the thesis has shown that ESBL production and fluoroquinolone resistance is rapidly spreading in Malawi across multiple E. coli and K. pneumoniae lineages that are causing increasing levels of infection. As cephalosporins and fluoroquinolones remain the last resort antimicrobial agents in this setting, urgent action is needed to curb the spread of Gram-negative AMR pathogens
Open access self-archiving: An author study
No full textThis, our second author international, cross-disciplinary study on open access had 1296 respondents. Its focus was on self-archiving. Almost half (49%) of the respondent population have self-archived at least one article during the last three years. Use of institutional repositories for this purpose has doubled and usage has increased by almost 60% for subject-based repositories. Self-archiving activity is greatest amongst those who publish the largest number of papers. There is still a substantial proportion of authors unaware of the possibility of providing open access to their work by self-archiving. Of the authors who have not yet self-archived any articles, 71% remain unaware of the option. With 49% of the author population having self-archived in some way, this means that 36% of the total author population (71% of the remaining 51%), has not yet been appraised of this way of providing open access. Authors have frequently expressed reluctance to self-archive because of the perceived time required and possible technical difficulties in carrying out this activity, yet findings here show that only 20% of authors found some degree of difficulty with the first act of depositing an article in a repository, and that this dropped to 9% for subsequent deposits. Another author worry is about infringing agreed copyright agreements with publishers, yet only 10% of authors currently know of the SHERPA/RoMEO list of publisher permissions policies with respect to self-archiving, where clear guidance as to what a publisher permits is provided. Where it is not known if permission is required, however, authors are not seeking it and are self-archiving without it. Communicating their results to peers remains the primary reason for scholars publishing their work; in other words,
researchers publish to have an impact on their field. The vast majority of authors (81%) would willingly comply with a mandate from their employer or research funder to deposit copies of their articles in an institutional or subject-based repository. A further 13% would comply reluctantly; 5% would not comply with such a mandate
Progress of international hydrogen production network for the thermochemical Cu–Cl cycle
No full textThis paper presents recent advances by an international team which is developing the thermochemical copper–chlorine (Cu–Cl) cycle for hydrogen production. Development of the Cu–Cl cycle has been pursued by several countries within the framework of the Generation IV International Forum (GIF) for hydrogen production with the next generation of nuclear reactors. Due to its lower temperature requirements in comparison with other thermochemical cycles, the Cu–Cl cycle is particularly well matched with Canada's Generation IV reactor, SCWR (Super-Critical Water Reactor), as well as other heat sources such as solar energy or industrial waste heat. In this paper, recent developments of the Cu–Cl cycle are presented, specifically involving unit operation experiments, corrosion resistant materials and system integration.Atomic Energy of Canada LimitedOntario Research Excellence FundNatural Sciences and Engineering Research Council of CanadaUniversity Network of Excellence in Nuclear Engineering (UNENE)Canada Research Chairs progra
ŻYCIE UKRYTE W SŁOWIE. "BEKSIŃSCY. PORTRET PODWÓJNY" MAGDALENY GRZEBIAŁKOWSKIEJ W ŚWIETLE POSTSTRUKTURALIZMU
No full textLife Hidden in Words. Magdalena Grzebiałkowska\u27s "Beksińscy. Portret podwójny" and Poststructuralism
The article analyzes Magdalena Grzebiałkowska\u27s biographical "Beksińscy. Portret podwójny" which focuses on the lives of Zdzisław Beksiński and Tomasz Beksiński. The author looks at the construction of the biography and its relationship to poststructuralism, which allows for an appreciation of the literary features of the book. He points to how the specificity of the content, language, a mode of narration in Grzebiałkowska\u27s book make it a full-fledged literary work itself. As such the book departs from a typical biographical scheme. Juxtaposing the book with poststructural ideas leads to the reconsideration of the role of the author in the process of shaping of a biographical narrative
Systems, methods and devices for the capture and hydrogenation of carbon dioxide with thermochemical Cu—Cl and Mg—Cl—Na/K—CO2 cycles
No full textSystems, methods, and devices for producing hydrogen and capturing CO2 from emissions combine both H2 production and CO2 capture processes in forms of thermochemical cycles to produce useful products from captured CO2. The thermochemical cycles are copper-chlorine (Cu—Cl) and magnesium-chlorine-sodium/potassium cycles (Mg—Cl—Na/K—CO2). One system comprises a Cu—Cl cycle, a CO2 capture loop, and a hydrogenation cycle. Another system comprises an Mg—Cl—Na/K—CO2 cycle and a hydrogenation cycle. Devices for hydrogen production, CO2 capture, hydrogenation, and process and equipment integration include a two-stage fluidized/packed bed, hybrid two-stage spray-fluidized/packed bed reactor, a two-stage wet-mode absorber, a hybrid two-stage absorber, and a catalyst packed/fluidized bed reactor
Clean hydrogen production with the Cu–Cl cycle – Progress of international consortium, I: Experimental unit operations
No full textAdvancement of the thermochemical copper–chlorine (Cu–Cl) cycle for hydrogen production is reviewed and discussed in this paper. Individual unit operations and their linkage into an integrated cycle are being developed by a Canadian consortium, as part of the Generation IV International Forum (GIF) for hydrogen production with the next generation of nuclear reactors. This paper focuses on the consortium’s latest advances on the Cu–Cl cycle, particularly with respect to hydrogen production with Canada’s Generation IV reactor, called SCWR (Super-Critical Water Reactor). Other heat sources may also be utilized for the Cu–Cl cycle, such as solar energy or industrial waste heat. In this first of two companion papers, recent developments in Canada’s nuclear hydrogen program are reported, specifically unit operation experiments of the Cu–Cl cycle and system integration. The following second companion paper will present system modeling with Aspen Plus, corrosion resistant materials, thermochemistry, safety, and reliability aspects of the Cu–Cl cycle.Atomic Energy of Canada LimitedOntario Research Excellence FundNatural Sciences and Engineering Research Council of CanadaUniversity Network of Excellence in Nuclear Engineering (UNENE)Canada Research Chairs progra
Canada’s program on nuclear hydrogen production and the thermochemical Cu–Cl cycle
No full textThis paper presents an overview of the status of Canada’s program on nuclear hydrogen production and the thermochemical copper–chlorine (Cu–Cl) cycle. Enabling technologies for the Cu–Cl cycle are being developed by a Canadian consortium, as part of the Generation IV International Forum (GIF) for hydrogen production with the next generation of nuclear reactors. Particular emphasis in this paper is given to hydrogen production with Canada’s Super-Critical Water Reactor, SCWR. Recent advances towards an integrated lab-scale Cu–Cl cycle are discussed, including experimentation, modeling, simulation, advanced materials, thermochemistry, safety, reliability and economics. In addition, electrolysis during off-peak hours, and the processes of integrating hydrogen plants with Canada’s nuclear plants are presented.Atomic Energy of Canada LimitedOntario Research Excellence FundArgonne National Laboratory (International Nuclear Energy Research Initiative; U.S. Department of Energy)Natural Sciences and Engineering Research Council of Canada (NSERC)University Network of Excellence in Nuclear Engineering (UNENE)Canada Research Chairs (CRC
K-shell Photoionization of Atomic Cl
No full textRecent measurements of the photoionization of atomic Cl in the vicinity of the 1s thresholds have motivated the present R-matrix calculation which takes into account relativistic effects via the Breit-Pauli operator. The computer code CIV3 of Hibbert and Glass and Hibbert, which also includes relativistic effects, is used to obtain the discrete wavefunctions. These are constructed with orbitals generated from a carefully-chosen large scale configuration interaction expansion. The open-shell nature of the Cl atom translates into the existence of actually four 1s thresholds, 3Po 0,1,2 and 1P 1. The results are analyzed with particular focus on the resonances leading up to the four thresholds, and the various effects that dominate the cross sections in this energy range are unraveled
Integrated gasification and Cu–Cl cycle for trigeneration of hydrogen, steam and electricity
No full textThis paper develops and analyzes an integrated process model of an Integrated Gasification Combined Cycle (IGCC) and a thermochemical copper–chlorine (Cu–Cl) cycle for trigeneration of hydrogen, steam and electricity. The process model is developed with Aspen HYSYS software. By using oxygen instead of air for the gasification process, where oxygen is provided by the integrated Cu–Cl cycle, it is found that the hydrogen content of produced syngas increases by about 20%, due to improvement of the gasification combustion efficiency and reduction of syngas NOx emissions. Moreover, about 60% of external heat required for the integrated Cu–Cl cycle can be provided by the IGCC plant, with minor modifications of the steam cycle, and a slight decrease of IGCC overall efficiency. Integration of gasification and thermochemical hydrogen production can provide significant improvements in the overall hydrogen, steam and electricity output, when compared against the processes each operating separately and independently of each other.Natural Sciences and Engineering Research Council of Canada (NSERC
JPL Author Database
No full textA viewgraph presentation describing the background, goals, implementation, uses and future development of JPL's author database is shown
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