2,844 research outputs found

    Constraint of systematic uncertainties in an electron neutrino search using muon neutrinos at MicroBooNE

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    MicroBooNE is a liquid argon time projection chamber which has been running in the Booster Neutrino Beam at Fermilab since 2015. The primary goal of MicroBooNE is investigation of the excess of electromagnetic events observed by the MiniBooNE collaboration. Due to limitations of the Cherenkov-based particle identification of MiniBooNE, this excess could be interpreted as either photon-like or electron-like. A photon-like excess would indicate that there are processes which are not well understood which could act as a background in neutrino oscillation measurements, while an electron-like excess could indicate the presence of sterile neutrinos, the existence of which is one of the most hotly debated questions in the field. This work will outline the MicroBooNE strategy for investigation of this low-energy excess, with particular attention given to the role of the muon neutrino sideband which is used as an important constraint on systematic uncertainties. A procedure has been developed in order to apply this constraint to an electron neutrino dataset, and it has been shown that the constraint results in an improvement to the sensitivity. In order to perform this constraint, an exclusive-state νμ CC selection has been developed, which results in 804 selected events from on-beam data. The ratio of the data with respect to simulation is R=0.78 ± 0.04 (stat.) ± 0.12 (syst.). In addition, this thesis presents a first measurement of the longitudinal ionisation electron diffusion coefficient from the MicroBooNE data, which is determined to be 3.73 (+0.70, -0.68) cm2/s

    Learning styles of 3rd year genetics students and their affection and perception of effectiveness of a range of instructional modes

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    Different students come into our classes with different past learning experiences with diverse backgrounds. They have acquired their preferred way to assimilating information and have settled into a mode of learning that is most effective for them. Teaching them in using a single dimensional approach inevitably will only facilitate effective learning to a small population of the student cohort. A questionnaire was administered to ascertain the range of preferred learning styles of a cohort of third year genetics students in an effort to understand the diversity of their learning styles and to fine tune instructional modes for the coming year. The questionnaire assessed the preferred sensory modes in which the students choose in the way they perceive, process and acquire information. Through a series of lectures, use of multi-media and guided inquiry case studies, group discussion and group presentation, students were also able to provide additional feedback as to the mode of instructional activity which they perceived that they enjoy and is most effective in learning human molecular genetics. This paper analyses the correlation of gender and the different learning styles of these students, the preference and perceived effectiveness of a range of instructional activities. Based of these findings a number of recommendations for improvements to instructional are also discussed

    Patient and economic impact of implementing a paediatric sepsis pathway in emergency departments in Queensland, Australia.

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    We examined systems-level costs before and after the implementation of an emergency department paediatric sepsis screening, recognition and treatment pathway. Aggregated hospital admissions for all children aged < 18y with a diagnosis code of sepsis upon admission in Queensland, Australia were compared for 16 participating and 32 non-participating hospitals before and after pathway implementation. Monte Carlo simulation was used to generate uncertainty intervals. Policy impacts were estimated using difference-in-difference analysis comparing observed and expected results. We compared 1055 patient episodes before (77.6% in-pathway) and 1504 after (80.5% in-pathway) implementation. Reductions were likely for non-intensive length of stay (- 20.8 h [- 36.1, - 8.0]) but not intensive care (-9.4 h [- 24.4, 5.0]). Non-pathway utilisation was likely unchanged for interhospital transfers (+ 3.2% [- 5.0%, 11.4%]), non-intensive (- 4.5 h [- 19.0, 9.8]) and intensive (+ 7.7 h, [- 20.9, 37.7]) care length of stay. After difference-in-difference adjustment, estimated savings were 596 [277, 942] non-intensive and 172 [148, 222] intensive care days. The program was cost-saving in 63.4% of simulations, with a mean value of 97,019[97,019 [- 857,273, $1,654,925] over 24 months. A paediatric sepsis pathway in Queensland emergency departments was associated with potential reductions in hospital utilisation and costs

    A Mammoth Task:Identifying Mammoth Ivory Using Raman Spectroscopy

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    A mammoth tusk contains an inner mineralized protein matrix of dentine and an outer layer of cementum. Enamel is only present on the tips of the tusks of young mammoths, and is worn away in older mammoths. Dentine is a mineralized connective tissue containing the inorganic component of dahlite [Ca10(PO4)6(CO3)H2O]. To determine the species from which ivory originated, often destructive methods are used. Raman spectroscopy is a non-invasive laser-based technique that has proven applications in the chemistry of mineralized tissue. Ivory and bone have similar biochemical properties. The aim of this study is to test the hypothesis that mammoth ivory is identifiable using Raman spectroscopy. Mammoth tusks were kindly loaned from the Natural History Museum, London, UK. All tusks were from the species Mammuthus primigenius discovered either in Lyakhov Islands or next to the Yenisei river, Krasnoyarsk (Siberia, Russia) and span the Pleistocene epoch, Cenerzoic era. The ivory was scanned with an inVia Raman micro spectrometer (Renishaw Ltd) equipped with a x50 objective lens and a 785nm laser. Spectra were acquired using line maps on cross sections of two samples, and individual spectral points were acquired independently at random or at points of interest on all samples. Data was analysed with principal component analysis (PCA) using an in-house Matlab script. To date, the results of this study establishes that well preserved mammoth ivory can be characterized through the comparison of peak intensity ratios between organic v(CH) collagen peaks and inorganic v(PO) hydroxyapatite peaks. Differences were observed in the hydroxyapatite peak from spectra acquired near the medulla of the tusk compared to the cortex. This suggests that the tusk is more mineralized towards the cortex compared to dentine found closer to the medulla. A comparison of the average data from each mammoth tusk demonstrated that the mammoth spectral ‘fingerprint’ remains similar for all samples, though there was some inter-variation in the mineralization of the tusks from mammoths of the same species. Further work in this study aims to compare the Raman spectra between mammoth and elephant ivory. This will have direct applications in archaeology, as the species from which an ivory sample is found could be identified without the need for more traditional, destructive techniques of valuable artefacts. Additionally, international trade regulations require proof of the species from which ivory is obtained. The information obtained in this study will be valuable in developing quick and non-destructive methods for the identification of ivory from an unknown origin

    The HIPASS survey of the Galactic plane in Radio Recombination Lines

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    We present a Radio Recombination Line (RRL) survey of the Galactic Plane from the HI Parkes All-sky Survey and associated Zone of Avoidance survey, which mapped the region l=196degr -- 0degr --52degr and |b| < 5degr at 1.4 GHz and 14.4 arcmin resolution. We combine three RRLs, H168α\alpha, H167α\alpha, and H166α\alpha to derive fully sampled maps of the diffuse ionized emission along the inner Galactic plane. The velocity information, at a resolution of 20 km/s, allows us to study the spatial distribution of the ionized gas and compare it with that of the molecular gas, as traced by CO. The longitude-velocity diagram shows that the RRL emission is mostly associated with CO gas from the molecular ring and is concentrated within the inner 30degr of longitude. A map of the free-free emission in this region of the Galaxy is derived from the line-integrated RRL emission, assuming an electron temperature gradient with Galactocentric radius of 496±100496\pm100 K/kpc. Based on the thermal continuum map we extracted a catalogue of 317 compact (<15 arcmin) sources, with flux densities, sizes and velocities. We report the first RRL observations of the southern ionized lobe in the Galactic centre. The line profiles and velocities suggest that this degree-scale structure is in rotation. We also present new evidence of diffuse ionized gas in the 3-kpc arm. Helium and carbon RRLs are detected in this survey. The He line is mostly observed towards HII regions, whereas the C line is also detected further away from the source of ionization. These data represent the first observations of diffuse C RRLs in the Galactic plane at a frequency of 1.4 GHz.Comment: 20 pages, 14 figures. MNRAS accepte

    Hadronic interaction of eta and eta-prime mesons with nucleons

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    Due to their short life-time, flavour-neutral mesons cannot be utilized as free secondary beams or targets, and therefore a study of their interaction with nucleons is not possible via direct scattering experiments. This interaction is, however, accessible via its influence on the energy dependence - and on the phase space distributions of the cross sections for reactions in which these mesons are produced. In case of the p p --> p p eta reaction the experimentally determined distributions of the differential cross sections close to the production threshold cannot be described by taking into account the S-wave proton-proton and proton-eta interaction only. Here we show that the angular distributions determined at the COSY-11 facility reveal some evidence for P-wave admixture in the proton-proton subsystem already at an excess energy as low as Q = 15.5 MeV. We also present that one can estimate the relative strength of the eta-nucleon and eta-prime-nucleon interactions by comparison of the eta and eta-prime production yield.Comment: 4 pages, 3 figures, Talk given at 16th International Conference on Particles and Nuclei (PANIC 02), Osaka, Japan, 30 Sep - 4 Oct 200

    Experimental study of the eta-meson interaction with two-nucleons

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    By means of the COSY-11 detection system, using a stochastically cooled proton beam of the cooler synchrotron COSY and a hydrogen cluster target, we have performed a high statistics measurement of the pp --> pp eta reaction at an excess energy of Q = 15.5 MeV. The experiment was based on the four-momentum determination of both outgoing protons. This permits to identify pp --> pp eta events and to derive the complete kinematical information of the eta-p-p-system allowing for subsequent investigations of the eta-p interaction. The observed spectrum of the invariant mass of the proton-proton system deviates strongly from the phase-space distribution revealing the influence of the final-state-interaction among the outgoing particles or nontrivial features of the primary production mechanism.Comment: 6 pages, 4 figures, Talk presented at Meson 2002, 7th International Workshop on Meson Production, Properties and Interaction, Cracow, Poland, 24-28 May 200

    Heavy Meson Production at COSY - 11

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    The COSY-11 collaboration has measured the total cross section for the pp --> pp eta-prime and pp --> pp eta reactions in the excess energy range from Q = 1.5 MeV to Q = 23.6 MeV and from Q = 0.5 MeV to Q = 5.4 MeV, respectively. Measurements have been performed with the total luminosity of 73 nb^(-1) for the pp --> pp eta reaction and 1360 nb^(-1) for the pp --> pp eta-prime one. Recent results are presented and discussed.Comment: Invited talk at 4th International Conference on Physics at Storage Rings (STORI 99), Bloomington, Indiana, USA, September 12-16, 199

    Kaon Production and Interaction

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    Exclusive data on both the elementary kaon and antikaon production channels have been taken at the cooler synchrotron COSY in proton-proton scattering. In the kaon--hyperon production an enhancement by one order of magnitude of the Lambda/Sigma0 ratio has been observed at excess energies below Q=13 MeV compared to data at higher excess energies (Q>300 MeV). New results obtained at the COSY-11 facility explore the transition region between the regime of this low-energy Sigma0 suppression and excess energies of 60 MeV. A comparison of the energy dependence of the Lambda and Sigma0 total cross sections exhibits distinct qualitative differences between both hyperon production channels. Studies of kaon-antikaon production have been motivated especially by the ongoing discussion about the nature of the scalar resonances f0(980) and a0(980) coupling to the K anti-K channel. For the reaction pp->ppK+K- a first total cross section value is reported at an excess energy of Q=17 MeV, i.e. below the phi threshold. Calculations obtained within an OBE model indicate that the energy dependence of the available total cross section data close to threshold is rather difficult to reconcile with the assumption of a phase-space behaviour modified predominantly by the proton-proton final state interaction.Comment: 10 pages, 4 figures, Presented at Meson 2002: 7th International Workshop on Meson Production, Properties and Interaction, Cracow, Poland, 24-28 May 200
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