119 research outputs found
The sedimentology and depositional environment of the Beatrix Reef: Witwatersrand supergroup.
No full textA Dissertation Submitted to the Faculty of Science
University of the Witwatersrand, Johannesburg
for the Degree of Master of Science.Beatrix Mine is located 35 km south of the city of Welkom in
the Welkom Goldfield and as such forms the most southerly of
the Witwatersrand-type gold mines.
The Beatrix Reef overlies an angular unconformity at the
base of the Turffontein Subgroup, Central Rand Group
Significant, southerly truncation of over 600m of the
Johannesburg Subgroup, and the lower formations of the
Turffontein Subgroup, occur at this unconformity in the
Beatrix area..
characteristics of the Beatrix Reef conglomerates such as
the morphology, sorting and packing of clasts, and the
arrangement. of the sediments in various sedimentary
structures and facies/ sequences, suggest deposition within a
braided fluvial environment on a coarse-grained braid-delta.
Sedimentation occurred after the fluvial degradation of
previously deposited units, and culminated in a marine/
lacustrine transgression. Low aggradation rates led to
significant reworking and concentration of placer materials
in a depositional model probably typical of ventral Rand
Group placer formation. Heavy minerals (and gold) are
concentrated in response to hydraulic conditions and show a
close association with large and small scale sedimentary
features. Transport directions deduced from the sedimentary
structures suggest a north to south dispersal of sediment
down the braid plain.
Sedimentary structures in the finer rained units at the
base of the Eldorado Formation are indicative of tidal
influences and document the marine transgression as the
culmination of the degradational events.
The lithologys sedimentary structures and facies sequences
of the coarser grained units of the Eldorado Formation
well as the overall coarsening upward of these lithologies
indicate sedimentation in a braided , fluvial system, on an
alluvial fan prograding across the preyiously deposited
units" Sedimentary ~tructures and lithologic variations
confirm a continued north to south dispersal pattern.
In the area south of the Sand over the period of fluvial
degradation and transgression after the formation of the
Beatrix: Reef was followed by more rapidly aggreding fluvial
progradation due to a major change in base level in response
to compressional tectonics and uplift along the Western
Margin Structure. Only in post-Central Rand Group times did
relaxation and extensional tectonics result in the
outpourings of the Ventersdorp .supergroup lavas and the
cessation of active Witwatersrand Supergroup sedimentation.Andrew Chakane 201
Erratum: Changing epidemiology of candidaemia in Australia [J Antimicrob Chemother, 72, (2017) (1103-1108)] DOI:10.1093/jac/dkw422
No full textIn the original published version of this article two authors (Eunice Liu and Elaine Cheong) were inadvertently omitted from the author list during article preparation. This error has now been corrected. The authors apologize for this error
Coauthor Network Analysis of Journal of Applied Communications Articles from 2008-2017
No full textCoauthorship networks offer a glimpse of collaborations within a discipline, illustrating the social networks that enable users to leverage more resources than they could on their own. This study used relational bibliometric data from the last 10 years of the Journal of Applied Communications (JAC) to create a social network analysis. The following research objectives guided this study: 1) Describe authorship, category (i.e., research article, commentary, book review), and number of JAC papers published from 2008 to 2017, 2) Describe the coauthor network characteristics of JAC papers, and 3) Describe the relationship between publication frequency and social network characteristics of authors. Results showed the majority of articles published in JAC were research articles and written by more than one author. Typically, authors who were well connected in the network were those who collaborated with other faculty at their own institution and continued to collaborate with graduate school classmates after graduation. Based on the results, recommendations to broaden connections in agricultural communications included increasing collaborations based on research interests, as opposed to geographic proximity and past working relationships to increase connections across the agricultural communications discipline
The generic isogeny decomposition of the Prym Variety of a cyclic branched covering
No full textLet f: S′⟶ S be a cyclic branched covering of smooth projective surfaces over C whose branch locus Δ ⊂ S is a smooth ample divisor. Pick a very ample complete linear system | H| on S, such that the polarized surface (S, | H|) is not a scroll nor has rational hyperplane sections. For the general member [C] ∈ | H| consider the μn-equivariant isogeny decomposition of the Prym variety Prym(C′/C) of the induced covering f: C′: = f- 1(C) ⟶ C: Prym(C′/C)∼∏d|n,d≠1Pd(C′/C).We show that for the very general member [C] ∈ | H| the isogeny component Pd(C′/ C) is μd-simple with Endμd(Pd(C′/C))≅Z[ζd]. In addition, for the non-ample case we reformulate the result by considering the identity component of the kernel of the map Pd(C′/C)⊂Jac(C′)⟶Alb(S′). © 2022, The Author(s)
Subinhibitory concentrations of telithromycin, clarithromycin and azithromycin reduce methicillin-resistant Staphylococcus aureus coagulase in vitro and in vivo.
No full textBACKGROUND: Subinhibitory levels of clarithromycin and azithromycin have been shown to reduce the activity of bacterial virulence factors, but few studies have examined the effects of subinhibitory levels of telithromycin. Here, we examined the effects of telithromycin, clarithromycin and azithromycin on methicillin-resistant Staphylococcus aureus (MRSA) coagulase in vitro. We also examined the effects of these antibiotics on bacterial survival in a murine model of pulmonary infection, in which the number of bacteria in the lung correlates with the coagulase titre. METHODS: The coagulase titre in MRSA strain NUMR101, a clinical isolate, was measured after a 16 h treatment with telithromycin, clarithromycin or azithromycin at the MIC (512 mg/L) and 1/2, 1/4, 1/8 and 1/16 of the MIC. In addition, we examined the effect of these drugs in a murine model of pulmonary infection induced by the intravenous injection of S. aureus enmeshed in agar beads. Treatment was started 1 day before infection and mice were treated once a day for 7 days by oral administration of 10 or 100 mg/kg telithromycin, clarithromycin or azithromycin, and the number of viable bacteria in the lungs was counted 24 h after the injection of the bacteria. RESULTS: The coagulase titres in mice treated with 1/8 of the MIC of telithromycin, clarithromycin and azithromycin and in the control were 8, 4, 8 and 32, respectively. In the mouse model of infection, the log cfu/lung (mean +/- SEM; n = 5 or 6) were 6.62 +/- 0.81, 4.79 +/- 0.41, 6.15 +/- 0.38 and 8.41 +/- 0.30 for mice treated with 100 mg/kg/day of telithromycin, clarithromycin and azithromycin and for controls, respectively (P < 0.05 for all groups versus control). CONCLUSIONS: Subinhibitory concentrations of telithromycin inhibit MRSA coagulase in vitro. In addition, the in vivo results indicate that pre-treatment with telithromycin, clarithromycin or azithromycin can reduce the bacterial load in a murine model of pulmonary infection.This is a pre-copy-editing, author-produced PDF of an article accepted for publication in Journal of Antimicrobial Chemotherapy following peer review. The definitive publisher-authenticated version The Journal of antimicrobial chemotherapy, 61(3), pp.647-650; 2008 is available online at: http://jac.oxfordjournals.org/cgi/content/abstract/61/3/647
Jac's River Adventure English and Welsh
No full textJac's River Adventure booklet includes a short poetic story and activity series about a river journey. Jac is presented as a descendent of Swansea Jack, a dog who is a local legend in the City and Council of Swansea, UK. Jac goes for an adventure up the River Tawe (that flows through Swansea City and Council) to the Brecon Beacons National Park and back again. Along the way she sees the ecology and hydrogeology of the river, geological features, historical built infrastructure, local places and more. The book was created for the children of Swansea, but could be of interest to others looking to integrate a river story into the classrooms or other learning environments.
Jac's River Adventure presented in Januchowski-Hartley, S.R., Giannoulatou, I.D., Evans, J., Howells, S., Jones, D., and Humphreys, H. (in prep). Jac’s River Adventure: exploring a cross-curriculum approach to share knowledge and learn about rivers in classrooms
*Corresponding author: Stephanie Januchowski-Hartley, [email protected] or [email protected] </p
Pharmacokinetic analysis to assess forgiveness of boosted saquinavir regimens for missed or late dosing
No full textObjectives: One potential concern of once-daily protease inhibitor administration is low trough concentrations and ultimately the 'forgiveness' or robustness in comparison with the originally licensed twice-daily dose. To give an estimation of 'forgiveness', we determined the length of time plasma drug concentrations were below target in HIV-infected patients receiving saquinavir/ritonavir regimens. Methods: Seventy-seven pharmacokinetic profiles (saquinavir/ritonavir 1000/100 mg twice daily, n = 34; 1600/100 mg once daily, n = 26; 2000/100 mg once daily, n = 17) from five studies were combined, presented as twice- and once-daily percentiles (P10 - P90) and compared. At percentiles where trough concentrations fell below the alleged minimum effective concentration (MEC; 100 ng/mL), the length of time below MEC was determined. Results: Saquinavir concentrations were below MEC at P10 for 0.7 h for twice-daily saquinavir/ritonavir when compared with 8.6 and 6.6 h for 1600/100 and 2000/100 mg once daily, respectively. At P25, 1600/100 mg once daily produced suboptimal concentrations for 5.5 h in contrast to 0.5 h for 2000/100 mg once daily. Conclusions: Here, we provide substantive data that indicate once-daily saquinavir, in particular 1600/100 mg, is not as robust as the twice-daily regimen based on a population of UK patients; this raises concern over late or missed doses. However, pharmacokinetic data can only ever be a guide to the impact on long-term efficacy. © The Author 2008. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved
Modelling clinical data shows active tissue concentration of daclatasvir is 10-fold lower than its plasma concentration
No full textObjectives: Daclatasvir is a highly potent inhibitor of hepatitis C virus. We estimated the active tissue concentration of daclatasvir in vivo. Methods: We developed a mathematical model incorporating pharmacokinetic/pharmacodynamic and viral dynamics. By fitting the model to clinical data reported previously, we estimated the ratio between plasma drug concentration and active tissue concentration in vivo. Results: The modelling results show that the active tissue concentration of daclatasvir is ~9% of the concentration measured in plasma (95% CI 1%=29%). Conclusions: Using plasma concentrations as surrogates for clinical recommendations may lead to substantial underestimation of the risk of resistance. The Author 2013. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserve
The potential impact of the COVID-19 pandemic on global antimicrobial and biocide resistance: An AMR Insights global perspective
No full textCopyright © The Author(s) 2021. The COVID-19 pandemic presents a serious public health challenge in all countries. However, repercussions of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections on future global health are still being investigated, including the pandemic’s potential effect on the emergence and spread of global antimicrobial resistance (AMR). Critically ill COVID-19 patients may develop severe complications, which may predispose patients to infection with nosocomial bacterial and/or fungal pathogens, requiring the extensive use of antibiotics. However, antibiotics may also be inappropriately used in milder cases of COVID-19 infection. Further, concerns such as increased biocide use, antimicrobial stewardship/infection control, AMR awareness, the need for diagnostics (including rapid and point-of-care diagnostics) and the usefulness of vaccination could all be components shaping the influence of the COVID-19 pandemic. In this publication, the authors present a brief overview of the COVID-19 pandemic and associated issues that could influence the pandemic’s effect on global AMR
Efficacy and safety of rabeprazole, amoxicillin, and gatifloxacin after treatment failure of initial Helicobacter pylori eradication
No full textObjectives: To evaluate the efficacy of a 7-day regimen of gatifloxacin (400 mg daily), amoxicillin (1 g twice a day), and rabeprazole (20 mg twice a day) in the secondary eradication of Helicobacter pylori infection. Methods: Eligible patients with persistent infection following one or more conventional clarithromycin-containing triple therapies were enrolled in this open-label trial. Eradication of infection was documented by 14C-urea breath test a minimum of 4 weeks after therapy and 2 weeks off any acid suppressive therapy. Culture of H. pylori and in vitro susceptibility testing to amoxicillin, clarithromycin, and gatifloxacin was done in cases of failed eradication. Results: A total of 45 patients (22 females:23 males; mean age 44.5 ± 13 years) were enrolled. Eradication occurred in 38 patients [both per-protocol (PP) and intention-to-treat analysis: 84.4percent; 95percent CI: 74-95percent]. No significant adverse effects were reported. In vitro susceptibility testing showed no secondary resistance to gatifloxacin or amoxicillin in any of the seven nonresponders. Smoking, age, and sex were not predictors of potential eradication failure. Conclusions: A 7-day regimen of gatifloxacin, rabeprazole, and amoxicillin is effective after failed eradication therapy for H. pylori and does not appear to result in secondary resistance. 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