2,403 research outputs found

    An investigation of temperature distribution in cooled guide vanes

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    A numerical study to determine the temperature distribution in the guide vane blades of a radial inflow turbine is presented. A computer program was developed which permits the temperature distribution to be calculated when the blade is cooled internally using a combination of impingement and film cooling techniques. The study is based on the use of the finite difference method in a two dimensional heat conduction problem. The results are then compared to determine the best cooling configuration for a certain coolant to primary mass flow ratio

    Black Hole Relics in Large Extra Dimensions

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    Recent calculations applying statistical mechanics indicate that under the assumption of compactified large extra dimensions a black hole might evolve into a (quasi-)stable state with mass close to the new fundamental scale MfM_f. Black holes and therefore their relics might be produced at the {\sc LHC} in the case of extra-dimensional topologies. In this energy regime, Hawking's evaporation scenario is modified due to energy conservation and quantum effects. We reanalyse the evaporation of small black holes including the quantisation of the emitted radiation due to the finite surface of the black hole. It is found that observable stable black hole relics with masses 13Mf\sim 1-3 M_f are formed which can be identified by a delayed single jet with a corresponding hard momentum kick to the relic and by ionisation, e.g. in a TPC

    Very High Energy gamma-ray observations of Mrk 501 using TACTIC imaging gamma-ray telescope during 2005-06

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    In this paper we report on the Markarian 501 results obtained during our TeV γ\gamma-ray observations from March 11 to May 12, 2005 and February 28 to May 7, 2006 for 112.5 hours with the TACTIC γ\gamma-ray telescope. During 2005 observations for 45.7 hours, the source was found to be in a low state and we have placed an upper limit of 4.62 ×\times 1012^{-12} photons cm2^{-2} s1^{-1} at 3σ\sigma level on the integrated TeV γ\gamma-ray flux above 1 TeV from the source direction. However, during the 2006 observations for 66.8h, detailed data analysis revealed the presence of a TeV γ\gamma-ray signal from the source with a statistical significance of 7.5σ\sigma above EγE_{\gamma}\geq 1 TeV. The time averaged differential energy spectrum of the source in the energy range 1-11 TeV is found to match well with the power law function of the form (dΦ/dE=f0EΓd\Phi/dE=f_0 E^{-\Gamma}) with f0=(1.66±0.52)×1011cm2s1TeV1f_0=(1.66\pm0.52)\times 10^{-11}cm^{-2}s^{-1}TeV^{-1} and Γ=2.80±0.27\Gamma=2.80\pm0.27.Comment: 16 pages and 8 Figures Accepted for publication in the Journal of Physics

    Measurement of the proton and deuteron structure functions, F2p and F2d, and of the ratio sigma(L)/sigma(T)

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    The muon-proton and muon-deuteron inclusive deep inelastic scattering cross sections were measured in the kinematic range 0.002 < x < 0.60 and 0.5 < Q2 < 75 GeV2 at incident muon energies of 90, 120, 200 and 280 GeV. These results are based on the full data set collected by the New Muon Collaboration, including the data taken with a small angle trigger. The extracted values of the structure functions F2p and F2d are in good agreement with those from other experiments. The data cover a sufficient range of y to allow the determination of the ratio of the longitudinally to transversely polarised virtual photon absorption cross sections, R= sigma(L)/sigma(T), for 0.002 < x < 0.12 . The values of R are compatible with a perturbative QCD prediction; they agree with earlier measurements and extend to smaller x.Comment: In this replacement the erroneously quoted R values in tables 3-6 for x>0.12, and R1990 values in tables 5-6 for all x, have been corrected, and the cross sections in tables 3-4 have been adapted. Everything else, including the structure functions F2, remained unchanged. 22 pages, LateX, including figures, with two .sty files, and three separate f2tab.tex files for the F2-tables. Accepted for publication in Nucl.Phys.B 199

    Multifaceted intervention to reduce haemodialysis catheter related bloodstream infections: REDUCCTION stepped wedge, cluster randomised trial.

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    OBJECTIVE: To identify whether multifaceted interventions, or care bundles, reduce catheter related bloodstream infections (CRBSIs) from central venous catheters used for haemodialysis. DESIGN: Stepped wedge, cluster randomised design. SETTING: 37 renal services across Australia. PARTICIPANTS: All adults (age ≥18 years) under the care of a renal service who required insertion of a new haemodialysis catheter. INTERVENTIONS: After a baseline observational phase, a service-wide, multifaceted intervention bundle that included elements of catheter care (insertion, maintenance, and removal) was implemented at one of three randomly assigned time points (12 at the first time point, 12 at the second, and 13 at the third) between 20 December 2016 and 31 March 2020. MAIN OUTCOMES MEASURE: The primary endpoint was the rate of CRBSI in the baseline phase compared with intervention phase at the renal service level using the intention-to-treat principle. RESULTS: 1.14 million haemodialysis catheter days of use were monitored across 6364 patients. Patient characteristics were similar across baseline and intervention phases. 315 CRBSIs occurred (158 in the baseline phase and 157 in the intervention phase), with a rate of 0.21 per 1000 days of catheter use in the baseline phase and 0.29 per 1000 days in the intervention phase, giving an incidence rate ratio of 1.37 (95% confidence interval 0.85 to 2.21; P=0.20). This translates to one in 10 patients who undergo dialysis for a year with a catheter experiencing an episode of CRBSI. CONCLUSIONS: Among patients who require a haemodialysis catheter, the implementation of a multifaceted intervention did not reduce the rate of CRBSI. Multifaceted interventions to prevent CRBSI might not be effective in clinical practice settings. TRIAL REGISTRATION: Australia New Zealand Clinical Trials Registry ACTRN12616000830493

    Production of vector mesons by real and virtual photons at high energies

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    A model based on Reggeon field theory is used for the description of the photo- and electroproduction of vector mesons (ρ0,ω,ϕ,J/ψ\rho^0, \omega, \phi, J /\psi) on the proton. Its main feature is the dependence of the Pomeron intercept on the virtuality of the photon. The few parameters of the model were determined by fitting the total cross sections for real and virtual photons on the proton. This allows a parameter-free description of the energy dependence of vector meson production. Very good agreement with the existing high energy data is obtained.Comment: 6 pages and 3 figures included in a uuencoded fil