380 research outputs found

    Efficient sorting of Bessel beams

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    We demonstrate the efficient sorter of Bessel beams separating both the azimuthal and radial components. This is based upon the recently reported transformation of angular to transverse momentum states. We separately identify over forty azimuthal and radial components, with a radial spacing of 1588 m<sup>−1</sup>, and outline how the device could be used to identify the two spatial dimensions simultaneously

    Identification of the causal agent of Botryosphaeria stem canker in Ethiopian Eucalyptus plantations

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    Plantations of exotic Eucalyptus make up more than 30% of Ethiopia's plantations, providing fuel and construction timber to the country. Species such as E. camaldulensis, E. saligna, E. grandis, E. citriodora and E. globulus are most commonly planted. During a survey of Eucalyptus diseases in 2000 and 2001, Botryosphaeria stem canker was observed in most plantations. The disease symptoms included tip die- back, coppice failure and stem cankers characterised by kino exudation. The aim of this study was to identify the species responsible for Botryosphaeria stem canker in Ethiopia. Culture and conidial morphology, as well as DNA-based identification involving Restriction Fragment Length Polymorphisms (RFLPs) and sequencing of the Internal Transcribed Spacer regions (ITS) of the ribosomal RNA gene and the elongation factor 1-alpha (EF1-α) gene, were used to identify isolates. Pathogenicity studies were conducted in the greenhouse and under field conditions. Results showed that Botryosphaeria parva is responsible for Botryosphaeria stem canker of Eucalyptus in Ethiopia. This is the first report of the fungus from this country. Greenhouse and field inoculation studies showed that the Ethiopian isolates are highly virulent. Careful site species selection and breeding trials are thus needed to reduce the impact of this disease in Ethiopia

    Novel species of Calonectria associated with Eucalyptus leaf blight in Southeast China

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    Leaf blight caused by Calonectria spp. is an important disease occurring on Eucalyptus trees grown in plantations of Southeast Asia. Symptoms of leaf blight caused by Calonectria spp. have recently been observed in commercial Eucalyptus plantations in FuJian Province in Southeast China. The aim of this study was to identify these Calonectria spp. employing morphological characteristics, DNA sequence comparisons for the β-tubulin, histone H3 and translation elongation factor-1α gene regions and sexual compatibility. Four Calonectria spp. were identified, including Ca. pauciramosa and three novel taxa described here as Ca. crousiana, Ca. fujianensis and Ca. pseudocolhounii. Inoculation tests showed that all four Calonectria spp. found in this study were pathogenic on two different E. urophylla × E. grandis hybrid clones, commercially utilised in eucalypt plantations in China

    Proposed method to calculate asset values for road structures

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    The Public Finance Management Act (PFMA), requires national and provincial government departments to “prepare financial statements for each financial year in accordance with generally recognised accounting practice”. The Municipal Finance Management Act (MFMA) includes similar requirements for municipalities. The “generally recognised accounting practice” for national and provincial government departments is the Modified Cash Standard, being the reporting framework prescribed by the National Treasury, Office of the Accountant General (OAG). Municipalities have to comply with the Standards of Generally Recognised Accounting Practice 17 (GRAP 17). Both these accounting standards require that an immovable asset, which qualifies for recording as a capital asset such as road structures (bridges, major culverts, etc.), must be measured at its cost. Where the cost of an immovable asset cannot be determined accurately, the immovable asset should be measured at fair value. In the case of specialised buildings and other man-made structures, an entity need to estimate fair value using a depreciated replacement cost approach. Replacement cost is the value of an asset that replicates the existing asset most efficiently, while providing the same level of service. This paper describes a proposed method to calculate the depreciated replacement cost for road structures, such as bridges and major culverts. The replacement cost of a structure is the cost to replace the structure with a similar structure at current rates. It is based on a unit rate for the replacement cost. The depreciated replacement cost is the optimised replacement cost after deducting an allowance for wear or consumption to reflect the remaining or economic service life of the structure. This is achieved by multiplying the replacement cost of the structure with an average condition index. The average condition index is calculated using the degree and extent ratings from the DER-ratings for the structural elements of the structure. The DER-ratings are the degree, extent and relevancy ratings of defects on the structure, using the defects based rating system described in the draft TMH19 Manual for the Visual Assessment of Road StructuresPapers Presented at the 2018 37th Southern African Transport Conference 9-12 July 2018 Pretoria, South Africa. Theme "Towards a desired transport future: safe, sufficient and affordable"

    Fatty Acid Methyl Esters as Biosolvents of Epoxy Resins: A Physicochemical Study

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    The C8 to C18 fatty acid methyl esters (FAME) have been compared as solvents for two epoxy resin pre-polymers, bisphenol A diglycidyl ether (DGEBA) and triglycidyl paminophenol ether (TGPA). It was found that the solubilization limits vary according to the ester and that methyl caprylate is the best solvent of both resins. To explain these solubility performances, physical and chemical properties of FAME were studied, such as the Hansen parameters, viscosity, binary diffusion coefficient and vaporization enthalpy. Determination of the physicochemical parameters of FAME was carried out by laboratory experimentations and by calculation from bibliographic data. The Hansen parameters of FAME and epoxy resins pre-polymers were theoretically and experimentally determined. The FAME chain length showed a long dependence on the binary diffusion parameters and kinematic viscosity, which are mass and momentum transport properties. Moreover, the vaporization enthalpy of these compounds was directly correlated with the solubilization limits

    First Principles NMR Study of Fluorapatite under Pressure

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    NMR is the technique of election to probe the local properties of materials. Herein we present the results of density functional theory (DFT) \textit{ab initio} calculations of the NMR parameters for fluorapatite (FAp), a calcium orthophosphate mineral belonging to the apatite family, by using the GIPAW method [Pickard and Mauri, 2001]. Understanding the local effects of pressure on apatites is particularly relevant because of their important role in many solid state and biomedical applications. Apatites are open structures, which can undergo complex anisotropic deformations, and the response of NMR can elucidate the microscopic changes induced by an applied pressure. The computed NMR parameters proved to be in good agreement with the available experimental data. The structural evaluation of the material behavior under hydrostatic pressure (from --5 to +100 kbar) indicated a shrinkage of the diameter of the apatitic channel, and a strong correlation between NMR shielding and pressure, proving the sensitivity of this technique to even small changes in the chemical environment around the nuclei. This theoretical approach allows the exploration of all the different nuclei composing the material, thus providing a very useful guidance in the interpretation of experimental results, particularly valuable for the more challenging nuclei such as 43^{43}Ca and 17^{17}O.Comment: 8 pages, 2 figures, 3 table

    The BEST study - a prospective study to compare business class versus economy class air travel as a cause of thrombosis

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    Background. As many as 10% of airline passengers travelling without prophylaxis for long distances may develop a venous thrombosis. There is, however, no evidence that economy class travellers are at increased risk of thrombosis.Objectives. A suitably powered prospective study, based on the incidence of deep-vein thrombosis (DVT) reported in previous studies on long-haul flights, was designed to determine the incidence of positive venous duplex scans and D-dimer elevations in low and intermediate-risk passengers, comparing passengers travelling in business and economy class.Patients/methods. Eight hundred and ninety-nine passengers were recruited (180 travelling business class and 719 travelling economy). D-dimers were measured before and after the flight. A value greater than 500 ng/ml was accepted as abnormal. A thrombophilia screen was conducted which included the factor V Leiden mutation, the prothombin 20210A mutation, protein C and S levels, antithrombin levels, and anticardiolipin antibodies immunoglobulin G (IgG) and immunoglobulin M (IgM). On arrival, lower limb compression ultrasonography of the deep veins was performed. Logistical regression analysis was used to determine the risk factors related to abnormally high D-dimer levels.Results. Only 434 subjects had a full venous duplex scan performed. None had ultrasonic evidence of venous thrombosis. Nine passengers tested at departure had elevated D-dimer levels and these volunteers were excluded from further study. Seventy-four of the 899 passengers had raised D-dimers on arrival. Twenty-two of 180 business class passengers (12%) developed elevated D-dimers compared with 52 of 719 economy class passengers (7%). There was no significant association between elevation of D-dimers and the class flown (odds ratio (OR) 0.61, p = 0.109). The factor V Leiden mutation, factor VIII levels and the use of aspirin were, however, associated with raised D-dimers (OR 3.36, p = 0.024; OR 1.01, p = 0.014; and OR 2.04, p = 0.038, respectively). Five hundred and five passengers were contacted within 6 months and none reported any symptoms of a clinical thrombosis or pulmonary embolus.Conclusion. The incidence of ultrasonically proven DVT is much lower than previously reported. However, more than 10% of all passengers developed raised D-dimers, which were unrelated to the class flown. A rise in D-dimers is associated with an inherent risk of thrombosis and/ or thrombophilia, demonstrates activation of both the coagulation and fibrinolytic systems during long-haul flights, and may indicate the development of small thrombi

    A randomized controlled trial of home visits by neighborhood mentor mothers to improve children's nutrition in South Africa

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    Malnourished children and babies with birth weights under 2500 g are at high risk for negative outcomes over their lifespans. Philani, a paraprofessional home visiting program, was developed to improve nutritional outcomes for young children in South Africa. One “mentor mother” was recruited from each of 37 neighborhoods in Cape Town, South Africa. Mentor mothers were trained to conduct home visits to weigh children under six years old and to support mothers to problem-solve life challenges, especially around nutrition. Households with underweight children were assigned randomly on a 2:1 ratio to the Philani program (n = 500) or to a standard care condition (n = 179); selection effects occurred and children in the intervention households weighed less at recruitment. Children were evaluated over a one-year period (n = 679 at recruitment and n = 638 with at least one follow-up; 94%). Longitudinal random effects models indicated that, over 12 months, the children in the intervention condition gained significantly more weight than children in the control condition. Mentor mothers who are positive peer deviants may be a viable strategy that is efficacious and can build community, and the use of mentor mothers for other problems in South Africa is discussed

    New and Interesting Fungi. 1

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    This study introduces two new families, one new genus, 22 new species, 10 new combinations, four epitypes, and 16 interesting new host and / or geographical records. Cylindriaceae (based on Cylindrium elongatum) is introduced as new family, with three new combinations.Xyladictyochaetaceae (based on Xyladictyochaetalusitanica) is introduced to accommodate Xyladictyochaeta. Pseudoanungitea gen. nov. (based on P.syzygii)is described on stems of Vaccinium myrtillus(Germany). New species include: Exophiala eucalypticola on Eucalyptus obliqua leaf litter, Phyllosticta hakeicola on leaves of Hakea sp.,Setophaeosphaeriacitricola on leaves of Citrus australasica, and Sirastachyscyperacearum on leaves of Cyperaceae(Australia); Polyscytalum chilense on leaves of Eucalyptus urophylla (Chile); Pseudoanungitea vaccinii on Vaccinium myrtillus (Germany); Teichospora quercus on branch tissue of Quercus sp. (France); Fusiconidiumlycopodiellae on stems of Lycopodiella inundata,Monochaetiajunipericola on twig of Juniperus communis,Myrmecridiumsorbicola on branch tissues of Sorbus aucuparia, Parathyridariaphiladelphi on twigs of Philadelphus coronarius, and Wettsteininaphiladelphi on twigs of Philadelphus coronarius (Germany); Zygosporium pseudogibbum on leaves of Eucalyptus pellita (Malaysia); Pseudoanungiteavariabilis on dead wood (Spain); Alfaria acaciae on leaves of Acacia propinqua, Dictyochaeta mimusopis on leaves of Mimusops caffra,and Pseudocercosporabreonadiae on leaves of Breonadia microcephala (South Africa); Colletotrichumkniphofiae on leaves of Kniphofia uvaria,Subplenodomusiridicola on Iris sp., and Trochila viburnicola on twig cankers on Viburnum sp. (UK); Polyscytalum neofecundissimum on Quercus robur leaf litter, and Roussoellaeuonymi on fallen branches of Euonymus europaeus (Ukraine). New combinations include: Cylindrium algarvense on leaves of Eucalyptus sp. (Portugal), Cylindrium purgamentum on leaf litter (USA), Cylindrium syzygii on leaves of Syzygium sp. (Australia), Microdochium musae on leaves of Musa sp. (Malaysia), Polyscytalum eucalyptigenum on Eucalyptus grandis × pellita (Malaysia), P. eucalyptorum on leaves of Eucalyptus (Australia), P. grevilleae on leaves of Grevillea (Australia), P. nullicananum on leaves of Eucalyptus (Australia), Pseudoanungiteasyzygii on Syzygium cordatum leaf litter (South Africa), and Setophaeosphaeriasidae on leaves of Sida sp. (Brazil). New records include: Sphaerellopsis paraphysata on leaves of Phragmites sp., Vermiculariopsiella dichapetali on leaves of Melaleuca sp. and Eucalyptus regnans, and Xyladictyochaetalusitanica on leaf litter of Eucalyptus sp. (Australia); Camarosporidiella mackenziei on twigs of Caragana sp. (Finland); Cyclothyriella rubronotata on twigs of Ailanthus altissima, Rhinocladiella quercus on Sorbus aucuparia branches (Germany); Cytospora viticola on stems of Vitis vinifera (Hungary); Echinocatena arthrinioides on leaves of Acacia crassicarpa (Malaysia); Varicosporellopsis aquatilis from garden soil (Netherlands); Pestalotiopsis hollandica on needles of Cupressus sempervirens (Spain), Pseudocamarosporiumafricanum on twigs of Erica sp. (South Africa), Pseudocamarosporium brabeji on branch of Platanus sp. (Switzerland); Neocucurbitaria cava on leaves of Quercus ilex (UK); Chaetosphaeriamyriocarpaon decaying wood of Carpinus betulus,Haplograhium delicatum on decaying Carpinus betulus wood (Ukraine). Epitypes are designated for: Elsinoë mimosae on leaves of Mimosa diplotricha (Brazil), Neohendersonia kickxii on Fagus sylvatica twig bark (Italy), Caliciopsis maxima on fronds of Niphidium crassifolium (Brazil), Dictyochaeta septata on leaves of Eucalyptus grandis ×urophylla (Chile), and Microdochium musae on leaves of Musa sp. (Malaysia)
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