654 research outputs found

    Identification of a mutation in the para-sodium channel gene of the cattle tick Rhipicephalus (Boophilus) microplus associated with resistance to synthetic pyrethroid acaricides

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    Resistance against synthetic pyrethroid (SP) products for the control of cattle ticks in Australia was detected in the field in 1984, within a very short time of commercial introduction. We have identified a mutation in the domain II S4-5 linker of the para-sodium channel that is associated with resistance to SPs in the cattle tick Rhipicephalus (Boophilus) microplus from Australia. The cytosine to adenine mutation at position 190 in the R. microplus sequence AF134216, results in an amino acid substitution from leucine in the susceptible strain to isoleucine in the resistant strain. A similar mutation has been shown to confer SP resistance in the whitefly, Bemisia tabaci, but has not been described previously in ticks. A diagnostic quantitative PCR assay has been developed using allele-specific Taqman® minor groove-binding (MGB) probes. Using the assay to screen field and laboratory populations of ticks showed that homozygote allelic frequencies correlated highly with the survival percentage at the discriminating concentration of cypermethrin

    Electron impact dissociative excitation of water within the adiabatic nuclei approximation

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    The R-matrix method is used to calculate dissociative excitation cross sections for the four lowest-lying electronically excited states of H2O in the energy range 5-15 eV. For the first time calculations are performed taking into account the nuclear motion by means of an adaptation of the adiabatic nuclei approximation. Cross sections are compared with previous and new fixed-nuclei results and also experiments. Resonance positions and widths are calculated for different geometries of the water molecule

    GTOBAS: fitting continuum functions with Gaussian-type orbitals

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    GTOBAS is a program for fitting Gaussian-type orbitals (GTOs) to Bessel and Coulomb functions over a finite range. The exponents of the GTOs are optimized using the method of Nestmann and Peyerimhoff [J. Phys. B 23 (1990) L773]. The appended module NUMCBAS provides the numerical Bessel and Coulomb functions required as input for the program. The use of GTO continuum basis sets is particularly important in electron–molecule scattering calculations when polyatomic targets are involved. Sample results for such calculations are also discussed

    The impact of heat on mortality and morbidity in the Greater Metropolitan Sydney Region: A case crossover analysis

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    Background: This study examined the association between unusually high temperature and daily mortality (1997-2007) and hospital admissions (1997-2010) in the Sydney Greater Metropolitan Region (GMR) to assist in the development of targeted health program

    Single crewing in English and Welsh policing: frequency and associations with violence towards and injuries in officers

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    There is limited contemporary evidence concerning whether single crewing – the deployment of unaccompanied police officers – presents a risk to officer safety. This exploratory self-report study examined the frequency of single crewing in England and Wales and associations with violence-related variables. Officers represented by the Police Federation of England and Wales contributed survey data on four forms of violent victimisation and injuries requiring medical attention arising from workrelated violence experienced over the 12 months to February 2016. Respondents for whom crewing was applicable to their role indicated the frequency with which they had been single crewed during the same period. Pearson’s χ 2 tests were used to characterise socio- and occupational-demographic factors associated with single crewing, violence, and injuries. Associations between single crewing frequency and the target variables were assessed using adjusted binary logistic regression to generate odds ratios and 95% confidence intervals. Among the 11,397 respondents who indicated that crewing was applicable to their role, 53% were often and 21% always single crewed. Relative to those who were never single crewed, the odds of being subjected to verbal insults and verbal threats were significantly elevated in officers who were often or always single crewed. The odds of physical attacks and injuries requiring medical attention were significantly elevated in officers who were always single crewed. There was no association between single crewing frequency and physical attacks with a weapon. These initial cross-sectional findings suggest that tailored crewing options might represent a means by which to reduce violence towards police officers. Keywords: crewing, injury, police, violence

    Origins of the Ambient Solar Wind: Implications for Space Weather

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    The Sun's outer atmosphere is heated to temperatures of millions of degrees, and solar plasma flows out into interplanetary space at supersonic speeds. This paper reviews our current understanding of these interrelated problems: coronal heating and the acceleration of the ambient solar wind. We also discuss where the community stands in its ability to forecast how variations in the solar wind (i.e., fast and slow wind streams) impact the Earth. Although the last few decades have seen significant progress in observations and modeling, we still do not have a complete understanding of the relevant physical processes, nor do we have a quantitatively precise census of which coronal structures contribute to specific types of solar wind. Fast streams are known to be connected to the central regions of large coronal holes. Slow streams, however, appear to come from a wide range of sources, including streamers, pseudostreamers, coronal loops, active regions, and coronal hole boundaries. Complicating our understanding even more is the fact that processes such as turbulence, stream-stream interactions, and Coulomb collisions can make it difficult to unambiguously map a parcel measured at 1 AU back down to its coronal source. We also review recent progress -- in theoretical modeling, observational data analysis, and forecasting techniques that sit at the interface between data and theory -- that gives us hope that the above problems are indeed solvable.Comment: Accepted for publication in Space Science Reviews. Special issue connected with a 2016 ISSI workshop on "The Scientific Foundations of Space Weather." 44 pages, 9 figure

    Tomato: a crop species amenable to improvement by cellular and molecular methods

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    Tomato is a crop plant with a relatively small DNA content per haploid genome and a well developed genetics. Plant regeneration from explants and protoplasts is feasable which led to the development of efficient transformation procedures. In view of the current data, the isolation of useful mutants at the cellular level probably will be of limited value in the genetic improvement of tomato. Protoplast fusion may lead to novel combinations of organelle and nuclear DNA (cybrids), whereas this technique also provides a means of introducing genetic information from alien species into tomato. Important developments have come from molecular approaches. Following the construction of an RFLP map, these RFLP markers can be used in tomato to tag quantitative traits bred in from related species. Both RFLP's and transposons are in the process of being used to clone desired genes for which no gene products are known. Cloned genes can be introduced and potentially improve specific properties of tomato especially those controlled by single genes. Recent results suggest that, in principle, phenotypic mutants can be created for cloned and characterized genes and will prove their value in further improving the cultivated tomato.
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