555 research outputs found

    A rapid method of estimating the abundance of immature blackflies (Diptera: Simuliidae)

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    A ten-point visual method of estimating the abundance of immature blackflies in the field is proposed and tested. The method is based on the comparison of larvae and pupae found on natural substrates, with ten diagrammatically prepared abundance classes. When estimates were based on the abundance of blackflies within a 4 x 4 cm area of highest density, there were no significant differences between estimates based on the ten-point visual method and those based on actual counts (P > 0,05). The time taken to assess the abundance of larval blackflies on 30 substrates was about 15 min, depending on substrate accessibility. Personal bias was assessed independently by four people, and was negligible when estimates were based on the highest densities within a 4 x 4 cm quadrat. The method tends to overlook very small larvae, and is not recommended for estimating overall population densities. However, the method provides a reliable, practical and rapid index of blackfly abundance suitable for use in blackfly control programmes.The 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.Water Research Commission.mn201

    Optimisation of Bacillus thuringiensis var. israelensis (Vectobac®) applications for the blackfly control programme on the Orange River, South Africa

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    The Orange River, South Africa’s largest river, is a critical water resource for the country. In spite of the clear economic benefits of regulating river flows through a series of impoundments, one of the significant undesirable ecological consequences of this regulation has been the regular outbreaks of the pest blackfly species Simulium chutteri and S. damnosum s.l. (Diptera: Simuliidae). The current control programme, carried out by the South African National Department of Agriculture, uses regular applications, by helicopter, of the target-specific bacterial larvicide Bacillus thuringiensis var. israelensis. While cost-benefit analyses show significant benefits to the control programme, benefits could potentially be further increased through applying smaller volumes of larvicide in an optimised manner, which incorporates upstream residual amounts of pesticide through downstream carry. Using an optimisation technique applied in the West African Onchocerciasis Control Programme, to a 136 km stretch of the Orange River which includes 31 blackfly breeding sites, we demonstrate that 28.5% less larvicide could be used to potentially achieve the same control of blackfly. This translates into potential annual savings of between R540 000 and R1 800 000. A comparison of larvicide volumes estimated using traditional vs. optimised approaches at different discharges, illustrates that the savings on optimisation decline linearly with increasing flow volumes. Larvicide applications at the lowest discharge considered (40 m3·s-1) showed the greatest benefits from optimisations, with benefits remaining but decreasing to a theoretical 30% up to median flows of 100 m3·s-1. Given that almost 70% of flows in July are less than 100 m3·s-1, we suggest that an optimised approach is appropriate for the Orange River Blackfly Control Programme, particularly for flow volumes of less than 100 m3·s-1. We recommend that trials be undertaken over two reaches of the Orange River, one using the traditional approach, and another using the optimised approach, to test the efficacy of using optimised volumes of B.t.i.Keywords: Simulium chutteri, Simulium damnosum, Orange River, flow regulation, Bacillus thuringiensis var. israelensis, optimisatio

    Control of pest blackflies (Diptera: Simuliidae) along the Orange River, South Africa: 1990-1995

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    The efficacy of Bacillus thuringiensis var. israelensis (B.t.i.) and temephos in controlling the pest blackfly Simulium chutteri Lewis along the middle Orange River between 1990 and 1995, was assessed. Larvicides were applied by helicopter to rapids and riffles between Hopetown and Onseepkans, a river distance of 807 km. Larvicidal efficacy was based on the change in larval abundance at selected sites before and after each treatment. The success of the control programme was assessed independently by local farmers, who ranked adult blackfly annoyance on a 4-point scale. Before treatment, blackfly annoyance showed consistent peaks in spring, and sometimes in autumn, and levels were unacceptably high for between 17 and 36 weeks of the year. After treatment started, blackfly annoyance levels were reduced significantly. The number of annual treatments necessary to reduce blackfly annoyance to acceptable levels was highly variable (3-13), and depended on river conditions, as well as the efficacy and timing of each treatment. During low-flow conditions (<50 mᵌ/s), applications became increasingly difficult in braided sections of the river, and dosage calculations were inaccurate because of local abstraction and return flows. Both larvicides worked well in winter (water temperature 11-13 °C). Control of the spring outbreak can be planned well in advance, with the first treatment starting in mid July. A flexible protocol is required to control outbreaks at other times of the year. We recommended the use of B.t.i. for most applications, with increased dosages during algal blooms (> 1 500 cells/ml). The use of temephos in the Orange River should be considered only during algal blooms or when flows exceed 300 m³/s. We conclude that helicopter application of larvicides is an effective method of controlling pest blackflies along the middle Orange River.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.Water Research Commissionmn201

    Implementing the Five-A Model of technical refinement: Key roles of the sport psychologist

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    There is increasing evidence for the significant contribution provided by sport psychologists within applied coaching environments. However, this rarely considers their skills/knowledge being applied when refining athletes’ already learned and well-established motor skills. Therefore, this paper focuses on how a sport psychologist might assist a coach and athlete to implement long-term permanent and pressure proof refinements. It highlights key contributions at each stage of the Five-A Model—designed to deliver these important outcomes—providing both psychomotor and psychosocial input to the support delivery. By employing these recommendations, sport psychologists can make multiple positive contributions to completion of this challenging task

    Increased risk of HPV-associated genital cancers in men and women as a consequence of pre-invasive disease

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    To assess the excess risk of HPV‐associated cancer (HPVaC) in two at‐risk groups – women with a previous diagnosis of high grade cervical intraepithelial neoplasia (CIN3) and both men and women treated for non‐cervical pre‐invasive ano‐genital disease. All CIN3 cases diagnosed in 1989‐2015 in Scotland were extracted from the Scottish cancer registry (SMR06). All cases of pre‐invasive penile, anal, vulval, and vaginal disease diagnosed in 1990‐2015 were identified within the NHS pathology databases in the two largest NHS health boards in Scotland. Both were linked to SMR06 to extract subsequent incidence of HPVaC following the diagnosis of CIN3 or pre‐invasive disease. Standardised incidence ratios were calculated for the risk of acquiring HPVaC for the two at‐risk groups compared with the general Scottish population. Among 69714 females in Scotland diagnosed with CIN3 (890360.9 person‐years), 179 developed non‐cervical HPVaC. CIN3 cases were at 3.2‐fold (95% CI: 2.7 to 3.7) increased risk of developing non‐cervical HPVaC, compared to the general female population. Among 1235 patients diagnosed with non‐cervical pre‐invasive disease (9667.4 person‐years), 47 developed HPVaC. Individuals with non‐cervical pre‐invasive disease had a substantially increased risk of developing HPVaC ‐ 15.5‐fold (95% CI: 11.1 to 21.1) increased risk for females and 28‐fold (11.3 to 57.7) increased risk for males. We report a significant additional risk of HPV‐associated cancer in those have been diagnosed with pre‐invasive HPV‐associated lesions including but not confined to the cervix. Uncovering the natural history of pre‐invasive disease has potential for determining screening, prevention and treatment

    Testing "microscopic" theories of glass-forming liquids

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    We assess the validity of "microscopic" approaches of glass-forming liquids based on the sole k nowledge of the static pair density correlations. To do so we apply them to a benchmark provided by two liquid models that share very similar static pair density correlation functions while disp laying distinct temperature evolutions of their relaxation times. We find that the approaches are unsuccessful in describing the difference in the dynamical behavior of the two models. Our study is not exhausti ve, and we have not tested the effect of adding corrections by including for instance three-body density correlations. Yet, our results appear strong enough to challenge the claim that the slowd own of relaxation in glass-forming liquids, for which it is well established that the changes of the static structure factor with temperature are small, can be explained by "microscopic" appr oaches only requiring the static pair density correlations as nontrivial input.Comment: 10 pages, 7 figs; Accepted to EPJE Special Issue on The Physics of Glasses. Arxiv version contains an addendum to the appendix which does not appear in published versio

    Re-examining the relationship between audiometric profile and tinnitus pitch

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    Objective: We explored the relationship between audiogram shape and tinnitus pitch to answer questions arising from neurophysiological models of tinnitus: ‘Is the dominant tinnitus pitch associated with the edge of hearing loss?’ and ‘Is such a relationship more robust in people with narrow tinnitus bandwidth or steep sloping hearing loss?’ Design: A broken-stick fitting objectively quantified slope, degree and edge of hearing loss up to 16 kHz. Tinnitus pitch was characterized up to 12 kHz. We used correlation and multiple regression analyses for examining relationships with many potentially predictive audiometric variables. Study Sample: 67 people with chronic bilateral tinnitus (43 men and 24 women, aged from 22 to 81 years). Results: In this ample of 67 subjects correlation failed to reveal any relationship between the tinnitus pitch and the edge frequency. The tinnitus pitch generally fell within the area of hearing loss. The pitch of the tinnitus in a subset of subjects with a narrow tinnitus bandwidth (n = 23) was associated with the audiometric edge. Conclusions: Our findings concerning subjects with narrow tinnitus bandwidth suggest that this can be used as an a priori inclusion criterion. A large group of such subjects should be tested to confirm these results

    Search for displaced vertices arising from decays of new heavy particles in 7 TeV pp collisions at ATLAS

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    We present the results of a search for new, heavy particles that decay at a significant distance from their production point into a final state containing charged hadrons in association with a high-momentum muon. The search is conducted in a pp-collision data sample with a center-of-mass energy of 7 TeV and an integrated luminosity of 33 pb^-1 collected in 2010 by the ATLAS detector operating at the Large Hadron Collider. Production of such particles is expected in various scenarios of physics beyond the standard model. We observe no signal and place limits on the production cross-section of supersymmetric particles in an R-parity-violating scenario as a function of the neutralino lifetime. Limits are presented for different squark and neutralino masses, enabling extension of the limits to a variety of other models.Comment: 8 pages plus author list (20 pages total), 8 figures, 1 table, final version to appear in Physics Letters
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