1,451 research outputs found

    The cosmic ray spectrum above 10(17) eV

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    The final analysis of the data obtained by the Sydney University Giant Airshower Recorder (SUGAR) is presented. The data has been reanalysed to take into account the effects of afterpulsing in the photomultiplier tubes. Event data was used to produce a spectrum of equivalent vertical muon number and from this a model dependent primary energy spectrum was obtained. These spectra show good evidence for the Ankle: a flattening at 10(19) eV. There is no sign of the cut-off which would be expected from the effects of the universal black body radiation

    The Second Virial Coefficient of Spin-1/2 Interacting Anyon System

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    Evaluating the propagator by the usual time-sliced manner, we use it to compute the second virial coefficient of an anyon gas interacting through the repulsive potential of the form g/r2(g>0)g/r^2 (g > 0). All the cusps for the unpolarized spin-1/2 as well as spinless cases disappear in the ω0\omega \to 0 limit, where ω\omega is a frequency of harmonic oscillator which is introduced as a regularization method. As gg approaches to zero, the result reduces to the noninteracting hard-core limit.Comment: 9 pages, 2 figs include

    Integrated nutrient and water management for sustainable food production in the Sahel

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    The symposium (2014) focused on the challenges of crop production faced by farmers in the Sahel region. The presentation covers a three-year fertilizer micro dosing (MD) project that was combined with rainwater harvesting (RWH). The techniques are assessed in terms of effects on crop production and family income. It also explores the “warrantage” or inventory credit system where harvested crops are stored and used as collateral to access loans and credit. With improving crop varieties, MD and RWH can increase yields up to 200%. There is no evidence that the process caused land degradation or yield decline, suggesting long term sustainability

    Pole structure of the Hamiltonian ζ\zeta-function for a singular potential

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    We study the pole structure of the ζ\zeta-function associated to the Hamiltonian HH of a quantum mechanical particle living in the half-line R+\mathbf{R}^+, subject to the singular potential gx2+x2g x^{-2}+x^2. We show that HH admits nontrivial self-adjoint extensions (SAE) in a given range of values of the parameter gg. The ζ\zeta-functions of these operators present poles which depend on gg and, in general, do not coincide with half an integer (they can even be irrational). The corresponding residues depend on the SAE considered.Comment: 12 pages, 1 figure, RevTeX. References added. Version to appear in Jour. Phys. A: Math. Ge

    Receiving the initial Down syndrome diagnosis: a comparison of prenatal and postnatal parent group experiences

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    This study explored the preliminary experiences of parents upon learning of their child's diagnosis of Down syndrome. Qualitative data from a web-based, national survey were analyzed based on two groups: prenatal (n  =  46) or postnatal (n  =  115) diagnosis. Three primary categories emerged from the data analysis: prenatal screening/testing decisions by parents, the adjustment process for parents, and postdiagnosis resources and support for parents. Participants' rationale behind pursuing testing ranged from wanting to be better prepared to not pursuing testing because it was not a factor in continuing the pregnancy. Participant reactions to the diagnosis involved a range of intense preliminary emotions; participants described their extreme grief and loss experience at the initial news of the diagnosis, which also was ambiguous in nature and required differing timelines of adjustment. Finally, participants described experiences with medical professionals, information/education, and faith/religion as resources and areas of support, although not all were described as positive in nature. Participants in both groups identified having negative experiences with medical professionals during the diagnosis process. The results indicated the importance of these early experiences for parents of children with Down syndrome and emphasize providing effective education, resources, and practical information from reliable sources

    Quantisation without Gauge Fixing: Avoiding Gribov Ambiguities through the Physical Projector

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    The quantisation of gauge invariant systems usually proceeds through some gauge fixing procedure of one type or another. Typically for most cases, such gauge fixings are plagued by Gribov ambiguities, while it is only for an admissible gauge fixing that the correct dynamical description of the system is represented, especially with regards to non perturbative phenomena. However, any gauge fixing procedure whatsoever may be avoided altogether, by using rather a recently proposed new approach based on the projection operator onto physical gauge invariant states only, which is necessarily free on any such issues. These different aspects of gauge invariant systems are explicitely analysed within a solvable U(1) gauge invariant quantum mechanical model related to the dimensional reduction of Yang-Mills theory.Comment: 22 pages, no figures, plain LaTeX fil

    A systematic review of current knowledge of HIV epidemiology and of sexual behaviour in Nepal

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    OBJECTIVE: To systematically review information on HIV epidemiology and on sexual behaviour in Nepal with a view to identifying gaps in current knowledge. METHODS: Systematic review covering electronic databases, web-based information, personal contact with experts and hand searching of key journals. RESULTS: HIV-1 seroprevalence has been rising rapidly in association with high-risk behaviours, with current levels of 40% amongst the nation's injecting drug users and approaching 20% amongst Kathmandu's female commercial sex workers (FCSWs). HIV seroprevalence remains low in the general population (0.29% of 15–49 year olds). There are significant methodological limitations in many of the seroprevalence studies identified, and these estimates need to be treated with caution. There are extensive migration patterns both within the country and internationally which provide the potential for considerable sexual networking. However, studies of sexual behaviour have focused on FCSWs and the extent of sexual networks within the general population is largely unknown. CONCLUSIONS: Whilst some of the ingredients are present for an explosive HIV epidemic in Nepal, crucial knowledge on sexual behaviour in the general population is missing. Research on sexual networking is urgently required to guide HIV control in Nepal. There is also a need for further good-quality epidemiological studies of HIV seroprevalence

    Manipulation of drugs to achieve the required dose is intrinsic to paediatric practice but is not supported by guidelines or evidence

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    Background: A lack of age-appropriate formulations can make it difficult to administer medicines to children. A manipulation of the dosage form may be required to achieve the required dose. This study aimed to describe medicines that are manipulated to achieve the required dose in paediatric practice.Method: A structured, undisguised observational study and postal survey. The observational study investigated drug manipulations occurring in clinical practice across three sites. The questionnaire, administered to a sample of paediatric nurses throughout the UK, surveyed manipulations conducted and nurses' experiences and views.Results: The observational study identified 310 manipulations, of which 62% involved tablets, 21% were intravenous drugs and 10% were sachets. Of the 54 observed manipulations 40 involved tablets with 65% of the tablets being cut and 30% dispersed to obtain a smaller dose. 188 manipulations were reported by questionnaire respondents, of these 46% involved tablets, 12% were intravenous drugs, and 12% were nebuliser solutions. Manipulations were predominantly, but not exclusively, identified in specialist clinical areas with more highly dependent patients. Questionnaire respondents were concerned about the accuracy of the dose achieved following manipulations and the lack of practice guidance.Conclusion: Manipulations to achieve the required dose occur throughout paediatric in-patient settings. The impact of manipulations on the efficacy of the drugs, the accuracy of the dose and any adverse effects on patients is not known. There is a need to develop evidence-based guidance for manipulations of medicines in children
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