101 research outputs found

    Aspects of rabies epidemiology in Tsumkwe District, Namibia

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    Aspects of rabies epidemiology were investigated in the Tsumkwe District, Namibia, during December 1993 and January 1994. A cross-sectional seroepidemiological survey for rabies antibodies was carried out in domestic (n = 70) and wild dogs [Lycaon pictus (n = 6)]. An overall seroprevalence rate of 30 % was found in domestic dogs, but it must be borne in mind that seroconversion can result from infections from either rabies or rabies-related viruses. Older dogs were more likely to be seropositive and there was spatial and temporal clustering of seropositivity. No wild dogs were found seropositive. A demographic survey of the domestic-dog population in the area showed that the total dog-population size was 132, or 0,027 dogs per square km . The dog population consisted mainly of young dogs with a median age of 1 ,5 years, and had a female bias of 0,63 males per female. Questionnaire surveys suggested that spotted hyaenas (Crocuta crocuta) and black-backed jackals (Canis mesomelas) were the most common larger carnivores found in and around villages, and that dogs were kept mainly for guarding.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat X Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.British Ecological Society, with indirect help from Grand Canyon Spur, Windhoek. Ministry of Environment and Tourism. WWF (US)

    Assessing Reputational Risk: A Four Point Matrix

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    Corporate strategies have been increasingly confronted with the need to measure and manage corporate reputation. Despite the importance associated with measuring and assessing reputational risk, the effectiveness of techniques that accomplish these tasks have not kept pac

    Pressure-gradient sorption calorimetry of flexible porous materials : implications for intrinsic thermal management

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    CITATION: Feldmann, W. K.; Esterhuysen, C. & Barbour, L. J. 2020. Pressure-Gradient Sorption Calorimetry of Flexible Porous Materials: Implications for Intrinsic Thermal Management. ChemSusChem, 13 (19): 5220-5223. doi:10.1002/cssc.202001469The original publication is available at https://chemistry-europe.onlinelibrary.wiley.com/journal/1864564xThermal management is an important consideration for applications that involve gas sorption by flexible porous materials. A pressure-gradient differential scanning calorimetric method was developed to measure the energetics of adsorption and desorption both directly and continuously. The method was applied to the uptake and release of CO2 by the well-known flexible metal–organic frameworks MIL-53(Al) and MOF-508b. High-resolution differential enthalpy plots and total integral enthalpy values for sorption allow comprehensive assessment of the thermal behavior of the materials throughout the entire sorption process. During adsorption, the investigated materials display the ability to offset exothermic adsorption enthalpy against endothermic structural transition enthalpy, and vice versa during desorption. The results show that flexible materials offer reduced total integral heat over a working range when compared to rigid materials.https://chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/cssc.202001469Publishers versio

    Foot-and-mouth disease and the African buffalo (Syncerus caffer). : II. Virus excretion and transmission during acute infection

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    Three groups of young buffalo in captivity were infected by exposing them to similar buffalo in the acute stages of infection induced by needle inoculation with SAT 1 or 2 viruses. Clear foot lesions developed in most of the buffalo from which the relevant virus types were re-isolated. During the first week following infection virus was found in blood, nasal secretions, saliva, preputial secretions and faeces. Air samples collected in the immediate vicinity of acutely infected buffalo were also found to contain virus. However, the regularity of virus detection as well as the quantity of virus in buffalo specimens was generally lower than for cattle infected with viruses of the same type. Conversely, virus was detected in the nasal secretions or saliva of 3 buffalo up to 4 weeks after infection, a situation which has not been encountered in cattle. Susceptible cattle and impala (Aepyceros melampus) were penned together with or in the immediate vicinity of infected buffalo and shared feeding and watering facilities with the buffalo. The pattern of transmission which emerged indicated that transfer of these viruses from buffalo to other species probably occurs only in the acute stages of infection and where there is direct physical contact between the speciesThe articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

    Direct determination of enthalpies of sorption using pressure-gradient differential scanning calorimetry: CO2 sorption by Cu-HKUST

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    CITATION: Feldmann, W. K. et al. 2020. Direct Determination of Enthalpies of Sorption Using Pressure-Gradient Differential Scanning Calorimetry: CO2 Sorption by Cu-HKUST. ChemSusChem, 13(1): 102-105. doi:10.1002/cssc.201902990The original publication is available at https://chemistry-europe.onlinelibrary.wiley.com/journal/1864564xEnthalpy of sorption (ΔH) is an important parameter for the design of separation processes using adsorptive materials. A pressure-ramped calorimetric method is described and tested for the direct determination of ΔH values. Combining a heatflow thermogram with a single sorption isotherm enables the determination of ΔH as a function of loading. The method is validated by studying CO2 sorption by the well-studied metal–organic framework Cu-HKUST over a temperature range of 288–318 K. The measured ΔH values compare well with previously reported data determined by using isosteric and calorimetric methods. The pressure-gradient differential scanning calorimetry (PGDSC) method produces reliable high-resolution results by direct measurement of the enthalpy changes during the sorption processes. Additionally, PGDSC is less labor-intensive and time-consuming than the isosteric method and offers detailed insight into how ΔH changes over a given loading range.https://chemistry-europe.onlinelibrary.wiley.com/doi/full/10.1002/cssc.201902990Publishers versio

    Intra-serotype SAT2 chimeric foot-and-mouth disease vaccine protects cattle against FMDV challenge

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    The genetic diversity of the three Southern African Territories (SAT) types of foot-and-mouth diseasevirus (FMDV) reflects high antigenic variation, and indications are that vaccines targeting each SAT-specific topotype may be needed. This has serious implications for control of FMD using vaccines as wellas the choice of strains to include in regional antigen banks. Here, we investigated an intra-serotypechimeric virus, vSAT2ZIM14-SAT2, which was engineered by replacing the surface-exposed capsid-codingregion (1B-1D/2A) of a SAT2 genome-length clone, pSAT2, with that of the field isolate, SAT2/ZIM/14/90.The chimeric FMDV produced by this technique was viable, grew to high titres and stably maintained the1B-1D/2A sequence upon passage. Chemically inactivated, oil adjuvanted vaccines of both the chimericand parental immunogens were used to vaccinate cattle. The serological response to vaccination showedthe production of strong neutralizing antibody titres that correlated with protection against homolo-gous FMDV challenge. We also predicted a good likelihood that cattle vaccinated with an intra-serotypechimeric vaccine would be protected against challenge with viruses that caused recent outbreaks insouthern Africa. These results provide support that chimeric vaccines containing the external capsid offield isolates induce protective immune responses in FMD host species similar to the parental vaccine.MSD Animal Health (previously Intervet SPAH)http://www.elsevier.com/locate/vaccine2016-06-30hb201

    Sequence-based prediction for vaccine strain selection and identification of antigenic variability in foot-and-mouth disease virus

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    Identifying when past exposure to an infectious disease will protect against newly emerging strains is central to understanding the spread and the severity of epidemics, but the prediction of viral cross-protection remains an important unsolved problem. For foot-and-mouth disease virus (FMDV) research in particular, improved methods for predicting this cross-protection are critical for predicting the severity of outbreaks within endemic settings where multiple serotypes and subtypes commonly co-circulate, as well as for deciding whether appropriate vaccine(s) exist and how much they could mitigate the effects of any outbreak. To identify antigenic relationships and their predictors, we used linear mixed effects models to account for variation in pairwise cross-neutralization titres using only viral sequences and structural data. We identified those substitutions in surface-exposed structural proteins that are correlates of loss of cross-reactivity. These allowed prediction of both the best vaccine match for any single virus and the breadth of coverage of new vaccine candidates from their capsid sequences as effectively as or better than serology. Sub-sequences chosen by the model-building process all contained sites that are known epitopes on other serotypes. Furthermore, for the SAT1 serotype, for which epitopes have never previously been identified, we provide strong evidence - by controlling for phylogenetic structure - for the presence of three epitopes across a panel of viruses and quantify the relative significance of some individual residues in determining cross-neutralization. Identifying and quantifying the importance of sites that predict viral strain cross-reactivity not just for single viruses but across entire serotypes can help in the design of vaccines with better targeting and broader coverage. These techniques can be generalized to any infectious agents where cross-reactivity assays have been carried out. As the parameterization uses pre-existing datasets, this approach quickly and cheaply increases both our understanding of antigenic relationships and our power to control disease

    Tracking the antigenic evolution of foot-and-mouth disease virus

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    Quantifying and predicting the antigenic characteristics of a virus is something of a holy grail for infectious disease research because of its central importance to the emergence of new strains, the severity of outbreaks, and vaccine selection. However, these characteristics are defined by a complex interplay of viral and host factors so that phylogenetic measures of viral similarity are often poorly correlated to antigenic relationships. Here, we generate antigenic phylogenies that track the phenotypic evolution of two serotypes of footand- mouth disease virus by combining host serology and viral sequence data to identify sites that are critical to their antigenic evolution. For serotype SAT1, we validate our antigenic phylogeny against monoclonal antibody escape mutants, which match all of the predicted antigenic sites. For serotype O, we validate it against known sites where available, and otherwise directly evaluate the impact on antigenic phenotype of substitutions in predicted sites using reverse genetics and serology. We also highlight a critical and poorly understood problem for vaccine selection by revealing qualitative differences between assays that are often used interchangeably to determine antigenic match between field viruses and vaccine strains. Our approach provides a tool to identify naturally occurring antigenic substitutions, allowing us to track the genetic diversification and associated antigenic evolution of the virus. Despite the hugely important role vaccines have played in enhancing human and animal health, vaccinology remains a conspicuously empirical science. This study advances the field by providing guidance for tuning vaccine strains via site-directed mutagenesis through this high-resolution tracking of antigenic evolution of the virus between rare major shifts in phenotype.S1 Data. VNT serological results for serotype O viruses and antisera.S2 Data. LPBE serological results for serotype O viruses and antisera.S3 Data. VNT serological results for serotype SAT1 viruses and antisera.S1 Table. Foot-and-mouth disease virus details with accession numbers.S2 Table. Pan-serotypic reference alignment of FMDV. The dataset shows the aligned VP2, VP3 and VP1 proteins of example SAT1 and O isolates used in the study alongside representative isolates from the other five serotypes. The four contiguous surface-exposed structural motifs confirmed as containing antigenic sites on at least four serotypes are highlighted in red–locations are approximate due to structural differences between the serotypes. The RGD cell surface receptor-binding motif, in the centre of the third site, is highlighted in blue.S3 Table. Residues identified as part of epitopes on structural proteins across the six tested serotypes of FMDV, along with corresponding positions on all serotypes.S4 Table. SAT1 mar-mutants.The authors acknowledge the Biotechnology and Biological Sciences Research Council (BBSRC) Institute Strategic Programme on Livestock Viral Diseases at The Pirbright Institute (BB/J004375/1) [RR SP DJP MM] and BBSRC BB/ G529532/1 [DWB MM], BB/F009186/1 [MM] and BBSRC BB/L004828 [RR] and BBSRC / Department for International Development / Scottish Government grants BB/H009302/1 [RR] and BB/H009175/1 [SP FFM RR] (http://www.bbsrc.ac.uk), and Department for Environment, Food and Rural Affairs grant SE2937 (http://www.gov.uk/defra) [MM]. The Food and Agriculture Organisation financially supported the research to determine one-way relationship and antigenic relatedness of SAT1 viruses under grants OSRO/RAF/721/EC and MTF/INT/003/EEC (http:// www.fao.org) [FFM AL JJE BB], and RMRSA (http:// www.rmrdsa.co.za) (Improving detection and characterisation methods for FMDV and ASFV for cattle and pigs in the SADC region) [BB]. Structural studies supported by the UK Medical Research Council grant MR/N00065X/1 [EEF] (http://www.mrc. ac.uk). The work of the Wellcome Trust Centre in Oxford is supported by the Wellcome Trust core award 090532/Z/07/Z [EEF] (http://www.wellcome.ac. uk).http://www.plosone.orgam2016Microbiology and Plant PathologyProduction Animal Studie

    Locus of control and online learning

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    The integration of online learning in university courses is considered to be both inevitable and necessary. Thus there is an increasing need to raise awareness among educators and course designers about the critical issues impacting on online learning. The aim of this study, therefore, was to assess the differences between two groups of first-year Business Sciences learners (online and conventional learners) in terms of biographic and demographic characteristics and locus of control. The study population consisted of 586 first-year learners of whom 185 completed the Locus of Control Inventory (LCI). The results show that the two groups of learners do not differ statistically significantly from each other with respect to locus of control. The findings and their implications are also discussed. Opsomming Die integrasie van aanlyn-leer in universiteitskursusse word beskou as sowel onafwendbaar as noodsaaklik. Daar is dus ’n toenemende behoefte om bewustheid onder opvoedkundiges en kursusontwerpers te kweek oor die kritiese aspekte wat ’n impak op aanlyn-leer het (Morgan, 1996). Daarom was die doel van hierdie ondersoek om die verskille tussen twee groepe eerstejaarleerders in Bestuurs- en Ekonomiese Wetenskap (aanlyn en konvensionele leerders) te bepaal ten opsigte van biografiese en demografiese eienskappe en lokus van beheer. Die populasie het bestaan uit 586 eerstejaarleerders waarvan 185 die Lokus van Beheer Vraelys voltooi het. Die resultate toon dat die twee groepe leerders nie statisties beduidend van mekaar verskil het met betrekking tot lokus van beheer nie. Die bevindinge en implikasies word ook bespreek

    Pentacarbonyl[methyl(n-propylsulfanyl)-carbene]chromium(0)

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    The title compound, [Cr(C5H10S)(CO)5], comprises a methyl(n-propylsulfanyl)carbene ligand coordinated to a pentacarbonylchromium fragment, with the Cr atom in an octahedral coordination. © 2006 International Union of Crystallography. All rights reserved.Articl
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