175 research outputs found
Compositional variability in mafic arc magmas over short spatial and temporal scales: Evidence for the signature of mantle reactive melt channels
No full textAbstractUnderstanding arc magma genesis is critical to deciphering the construction of continental crust, understanding the relationship between plutonic and volcanic rocks, and for assessing volcanic hazards. Arc magma genesis is complex. Interpreting the underlying causes of major and trace element diversity in erupted magmas is challenging and often non-unique. To navigate this complexity mafic magma diversity is investigated using sample suites that span short temporal and spatial scales. These constraints allow us to evaluate models of arc magma genesis and their geochemical implications based on physical arguments and recent model results. Young volcanic deposits (≲18 kyr) are analysed from the Southern Volcanic Zone (SVZ), Chile, in particular suites of scoria cones on the flanks of arc stratovolcanoes that have erupted relatively primitive magmas of diverse compositions. Our study is centred on the high-resolution post-glacial tephrochronological record for Mocho-Choshuenco volcano where tight age constraints and a high density of scoria cones provide a spatially well-resolved mafic magma dataset. Two compositional trends emerge from the data. Firstly, magmas from cones on the flanks of the main edifice become more mafic with distance from the central vent. This is attributed to fractional crystallisation processes within the crust, with distal cones sampling less differentiated magmas. Secondly, there is a set of cones with distinct major and trace element compositions that are more primitive but enriched in incompatible elements relative to the central system and other ‘normal SVZ’ magmas. This distinct signature – termed the ‘Kangechi’ signature – is observed at three further clusters of cones within the SVZ. This is attributed to greater preservation of the enriched melt signature arising from reactive melt transport within the mantle wedge. Our model has important implications for arc magma genesis in general, and in particular for the spatial and temporal scales over which compositional variations are preserved in erupted magmas
The chemistry of some dithiadiazolyls and their platinum complexes
No full textThe work outlined in this thesis is mainly concerned with the preparation and reactions of dithiadiazolylium salts, dithiadiazolyls and their Pt complexes. Chapter one outlines the chemistry, the synthesis and properties of dithiadiazolylium salts and dithiadiazolyls. Chapter two is concerned with the preparation and characterisation of some dithiadiazolyls and their platinum complexes, and comprehensive DSC and Ultraviolet/visible spectroscopic studies of these complexes, highlights some of their properties. Chapter three outlines the preparation and characterisation of some fluorine substituted dithiadiazolyls and their platinum complexes. It also discusses the crystal structures of the complex Pt(_3)[PPh(_3)](_4)[3,4-F(_2).C(_6)H(_3).CNSSN](_2) and the fluorine substituted dithiadiazolyls (2,3-F(_2).C(_6)H(_3).CNSSN)(_2) and (2,5-F(_2).C(_6)H(_3).CNSSN)-Chapter four outlines the main experimental techniques which were employed throughout my research. Appendix I contains additional crystallographic data, for the crystal structures mentioned previously, while Appendix II lists all the colloquia, lectures and seminars attended by the author
Corrigendum: A Severe Lack of Evidence Limits Effective Conservation of the World's Primates
No full textIn the originally published version of this article, the author's name, Kathy Slater, was incorrectly spelt in the author list and within the “Author Biographical” section. This has now been corrected online.Additional co-authors: Fabiano R de MELO, P Fan, Cyril C Grueter, Diana C Guzmán-Caro, Eckhard W Heymann, Ilka Herbinger, Minh D Hoang, Robert H Horwich, Tatyana Humle, Rachel A Ikemeh, Inaoyom S Imong, Leandro Jerusalinsky, Steig E Johnson, Peter M Kappeler, Maria Cecília M Kierulff, Inza Koné, Rebecca Kormos, Khac Q LE, Baoguo Li, Andrew J Marshall, Erik Meijaard, Russel A Mittermeier, Yasuyuki Muroyama, Eleonora Neugebauer, Lisa Orth, Erwin Palacios, Sarah K Papworth, Andrew J Plumptre, Ben M Rawson, Johannes Refisch, Jonah Ratsimbazafy, Christian Roos, Joanna M Setchell, Rebecca K Smith, Tene Sop, Christoph Schwitzer, Kathy Slater, Shirley C Strum, William J Sutherland, Maurício Talebi, Janette Wallis, Serge Wich, Roman M Wittig, Hjalmar S Küh
Life histories of burrowing mayflies (Hexagenia limbata and H. rigida, Ephemeroptera: Ephemeridae) in a northern Canadian reservoir
No full text1. The life histories and population dynamics of the burrowing mayflies Hexagenia limbata and H. rigida were examined from 1986 to 1988 in four regions of an impounded lake in northern Manitoba, Canada. 2. Bottom temperatures reached 15-20-degrees-C, but ice-free periods of 4-6 months resulted in annual degree day (dd > 10-degrees-C) accumulations of only 210-650 in various regions and years. 3. The life cycles (egg to adult) of both Hexagenia species required 3 yr in the three warmest regions studied and 4 yr in the coolest area; total dd accumulations to complete the life cycle ranged from 1222 to 1468 dd > 10-degrees-C. 4. Fecundity (no. of eggs/female) was strongly correlated to body size of subimagos, and subimago size was strongly correlated to length of nymphal exuviae, so field collection of nymphal exuviae could be used to determine both the size and fecundity of the emerging females. 5. Degree day accumulation in the final year before emergency was a better predictor of emergence timing than overall dd accumulations for the life cycle.PT: J; CR: BRITT NW, 1962, B OHIO BIOL SURVEY, V1, P1 BRITTAIN JE, 1982, ANNU REV ENTOMOL, V27, P19 BURTON W, 1973, J FISH RES BOARD CAN, V30, P287 CARLANDER KD, 1967, ECOLOGY, V48, P873 CLIFFORD HF, 1974, CAN ENTOMOL, V106, P1111 DANKS HV, 1987, BIOL SURVEY CANADA M, V1 EDMUNDS GF, 1976, MAYFLIES N CENTRAL A FLANNAGAN JF, 1979, 2ND P INT C EPH KRAK, P103 FREMLING CR, 1973, 1ST P INT C EPH LEID, P12 GIBERSON DJ, 1991, AMBIO, V20, P139 GIBERSON DJ, 1991, THESIS U MANITOBA WI GIBERSON DJ, 1992, 1837 CAN TECHN REP F GIBERSON DJ, 1992, J N AMER BENTHOL SOC, V11, P181 GIBERSON DJ, 1992, J N AMER BENTHOL SOC, V11, P194 HAMILTON AL, 1974, FISHERIES LIMNOLOG G, V1 HARPER F, 1981, CAN J ZOOL, V59, P1784 HECKY RE, 1984, CAN J FISH AQUAT SCI, V41, P579 HECKY RE, 1984, CAN J FISH AQUAT SCI, V41, P720 HEISE BA, 1987, J N AM BENTHOL SOC, V6, P230 HIGLEY LG, 1986, ENVIRON ENTOMOL, V15, P999 HUDSON PL, 1972, STUDIES NATURAL SCI, V1, P1 HUNT BP, 1951, FLORIDA ENTOMOLOGIST, V34, P59 HUNT BP, 1953, MICHIGAN DEP CONSERV, V4 LYMAN FE, 1944, ENTOMOL NEWS, V55, P207 MCCAFFERTY WP, 1975, T AM ENTOMOL SOC, V101, P447 MCCAFFERTY WP, 1984, ANN ENTOMOL SOC AM, V77, P69 MOZLEY SC, 1988, J GREAT LAKES RES, V14, P171 NEAVE F, 1932, CONTRIBUTIONS CANADI, V7, P177 NEWBURY RW, 1984, CAN J FISH AQUAT SCI, V41, P548 NEWBURY RW, 1984, CANADIAN J FISHERIES, V41, P558 OLIVER DR, 1960, J FISH RES BOARD CAN, V17, P607 PRUESS KP, 1983, ENVIRON ENTOMOL, V12, P613 RAWSON DS, 1953, J FISH RES BOARD CAN, V10, P486 RIKLIK L, 1982, CAN J ZOOL, V60, P2317 RUTTER RP, 1972, THESIS MIAMI U OXFOR SCHLOESSER DW, 1984, J GREAT LAKES RES, V10, P435 SOUTHWOOD TRE, 1978, ECOLOGICAL METHODS STANLEY EH, 1988, OIKOS, V51, P313 SWEENEY BW, 1978, SCIENCE, V200, P444 SWEENEY BW, 1984, ECOLOGY AQUATIC INSE, P56 TAKEMON Y, 1990, MAYFLIES STONEFLIES, P61 TOKESHI M, 1985, J ANIM ECOL, V54, P919 WELCH CL, 1989, HYDROBIOLOGIA, V185, P183 WHELAN KF, 1980, ADV EPHEMEROPTERA BI, P187 WIENS AP, 1984, CAN J FISH AQUAT SCI, V41, P638; NR: 45; TC: 10; J9: FRESHWATER BIOL; PG: 18; GA: PY758Source type: Electronic(1
Haematological and hepatic adverse effects of ceftriaxone in ambulatory care: a dual-centre retrospective observational analysis of standard vs high dose
No full textBACKGROUND: European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoint criteria for methicillin-susceptible Staphylococcus aureus (MSSA) treatment with ceftriaxone are based upon high dose (4 g/day) rather than standard dose (2 g/day) posology. This is particularly relevant for invasive infections, and for patients managed via Outpatient Parenteral Antimicrobial Therapy (OPAT), but may result in increased drug toxicity. We quantified the incidence of neutropenia, thrombocytopenia and raised liver enzymes between standard and high dose ceftriaxone in adult patients. METHOD: Adult outpatients prescribed ≥ 7 days of ceftriaxone therapy were identified, and clinical, pharmacological, and laboratory parameters extracted from electronic health records between May 2021 and December 2021. Incidence and median time to haematological and hepto-toxicity were analysed. Univariate odds ratios were calculated for neutrophil count and ALT levels with 95% confidence level and Chi squared/Fisher’s exact test used to identify statistical significance. RESULTS: Incidence of neutropenia was comparable between both groups; 8/47 (17%) in the 2 g group vs 6/39 (15.4%) in the 4 g group (OR 0.89 (95% CI 0.26–2.63), p > 0.999). Median time to neutropenia was 12 and 17 days in the 2 g and 4 g groups respectively. Thrombocytopenia was observed in 0/47 in the 2 g group compared with 3/39 (7.7%) in the 4 g group (p 0.089). Median time to thrombocytopenia was 7 days in the 4 g group. Elevated liver enzymes did not clearly correlate with ceftriaxone dosing; present in 5/47 (10.6%) and 2/39 (5.1%) for 2 g and 4 g respectively (OR 0.45 (95% CI 0.87–2.36), p 0.448). Treatment cessation due to any adverse effect was similar between both groups 2/47 (4.3%) for 2 g and 3/39 (7.7%) for 4 g (OR 1.86 (95% CI 0.36–10.92), p 0.655). CONCLUSIONS: Increased adverse effects with 4 g (over 2 g) daily dosing of ceftriaxone was not observed in an OPAT population. However absolute development of haematological and liver dyscrasias was appreciable—monitoring of liver function and full blood count in patients receiving prolonged ceftriaxone is indicated irrespective of dosing
Correspondence; author(s) include Joseph Carruthers, Sir Frederick M. Darley, Sir Harry Rawson; recipient(s) include Lord Northcote
No full textCoronavirus disease 2019 (COVID-19) impact on central-line-associated bloodstream infections (CLABSI): a systematic review
No full textIntroduction: Central line-associated bloodstream infections (CLABSI) are an important clinical and public health issue, impacted by the purported increase in healthcare-associated infections (including CLABSI) during the COVID-19 pandemic. This review evaluates the impact of COVID-19 on CLABSI at a global level, to determine risk factors, effective preventive measures and microbiological epidemiology. Methods: A systematic literature review was performed using a PECO framework, with COVID-19 infection as the exposure measure and CLABSI rates as the main outcome of interest, pre- and during the pandemic. Results: Overall, most studies (17 of N=21) found a significant increase in CLABSI incidence/rates during the pandemic. Four studies showed a reduction (N=1) or no increase (N=3). High workload, redeployment, and ‘overwhelmed’ healthcare staff were recurrent risk-factor themes, likely to have negatively influenced basic infection control practices, including compliance with hand hygiene and line care bundles. Microbiological epidemiology was also impacted, with an increase in enterococcal infections and other pathogens. Conclusion: The COVID-19 pandemic significantly impacted CLABSI incidence/rates. Observations from the different studies highlight significant gaps in healthcare associated infections (HCAI) knowledge and practice during the pandemic, and the importance of identifying preventive measures effective in reducing CLABSI, essential to health system resilience for future pandemics. Central to this are changes to CLABSI surveillance, as reporting is not mandatory in many healthcare systems. An audit tool combined with regular assessments of the compliance with infection control measures and line care bundles also remains an essential step in the prevention of CLABSI
Can precision antibiotic prescribing help prevent the spread of carbapenem-resistant organisms in the hospital setting?
No full textThe emergence of carbapenem-resistant organisms (CROs) is a significant global threat. Reduction of carbapenem consumption can decrease CROs. In the global endemic era of ESBL-producing bacteria, carbapenems are considered the treatment of choice, leading to challenge in limiting carbapenem use. This review describes the role of precision prescribing for prevention of CROs. This involves improving antibiotic selection, dosing and shortening duration. The effect of different antibiotics, dosing and duration on CRO development are explored. Available options for precision prescribing, gaps in the scientific evidence, and areas for future research are also presented
Treasures of the University : an examination of the identification, presentation and responses to artefacts of significance at the University of St Andrews, from 1410 to the mid-19th century; with an additional consideration of the development of the portrait collection to the early 21st century
No full textSince its foundation between 1410 and 1414 the University of St Andrews has acquired what can be considered to be ‘artefacts of significance’. This somewhat nebulous phrase is used to denote items that have, for a variety of reasons, been deemed to have some special import by the University, and have been displayed or otherwise presented in a context in which this status has been made apparent.
The types of artefacts in which particular meaning has been vested during the centuries under consideration include items of silver and gold (including the maces, sacramental vessels of the Collegiate Church of St Salvator, collegiate plate and relics of the Silver Arrow archery competition); church and college furnishings; artworks (particularly portraits); sculpture; and ethnographic specimens and other items described in University records as ‘curiosities’ held in the University Library from c. 1700-1838.
The identification of particular artefacts as significant for certain reasons in certain periods, and their presentation and display, may to some extent reflect the University's values, preoccupations and aspirations in these periods, and, to some degree, its identity. Consciously or subconsciously, the objects can be employed or operate as signifiers of meaning, representing or reflecting matters such as the status, authority and history of the University, its breadth of learning and its interest and influence in spheres from science, art and world cultures to national affairs.
This thesis provides a comprehensive examination of the growth and development of the University's holdings of 'artefacts of significance' from its foundation to the mid-19th century, and in some cases (especially portraits) beyond this date. It also offers insights into how the University viewed and presented these items and what this reveals about the University of St Andrews, its identity, which changed and developed as the living institution evolved, and the impressions that it wished to project
Towards a minimally invasive device for beta-lactam monitoring in humans
No full textAntimicrobial resistance is a leading patient safety issue. There is a need to develop novel mechanisms for monitoring and subsequently improving the precision of how we use antibiotics. A surface modified microneedle array was developed for monitoring beta-lactam antibiotic levels in human interstitial fluid. The sensor was fabricated by anodically electrodepositing iridium oxide (AEIROF) onto a platinum surface on the microneedle followed by fixation of beta-lactamase enzyme within a hydrogel. Calibration of the sensor was performed to penicillin-G in buffer solution (PBS) and artificial interstitial fluid (ISF). Further calibration of a platinum disc electrode was undertaken using amoxicillin and ceftriaxone. Open-circuit potentials were performed and data analysed using the Hill equation and log(concentration [M]) plots. The microneedle sensor demonstrated high reproducibility between penicillin-G runs in PBS with mean Km (± 1SD) = 0.0044 ± 0.0013 M and mean slope function of log(concentration plots) 29 ± 1.80 mV/decade (r2 = 0.933). Response was reproducible after 28 days storage at 4 °C. In artificial ISF, the sensors response was Km (± 1SD) = 0.0077 ± 0.0187 M and a slope function of 34 ± 1.85 mv/decade (r2 = 0.995). Our results suggest that microneedle array based beta-lactam sensing may be a future application of this AEIROF based enzymatic sensor
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