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Search Results: 1 - 10 of 415655 matches for " J E McMillan "
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Neutron shielding for particle astrophysics experiments
J. E. McMillan
Physics , 2005,
Abstract: Particle astrophysics experiments often require large volume neutron shields which are formed from hydrogenous material. This note reviews some of the available materials in an attempt to find the most cost effective solution. Raw polymer pellets and Water Extended Polyester (WEP) ae discussed in detail. Suppliers for some materials are given.
The measurement of scintillation emission spectra by a coincident photon counting technique
J E McMillan,C J Martoff
Physics , 2006,
Abstract: In the evaluation of novel scintillators, it is important to ensure that the spectrum of the light emitted by the scintillator is well matched to the response of the photomultiplier. In attempting to measure this spectrum using radioactive sources, it is found that so few photons are emitted per scintillation event that conventional spectroscopic techniques cannot easily be used. A simple photon counting technique is presented, using two photomultipliers operated in coincidence, the one viewing the scintillator directly, while the other views it through a monochromator. This system allows the spectrum to be measured without using specially cooled photomultipliers, intense radioactive sources or particle beams.
Simulations of muon-induced neutron flux at large depths underground
V. A. Kudryavtsev,N. J. C. Spooner,J. E. McMillan
Physics , 2003, DOI: 10.1016/S0168-9002(03)00983-5
Abstract: The production of neutrons by cosmic-ray muons at large depths underground is discussed. The most recent versions of the muon propagation code MUSIC, and particle transport code FLUKA are used to evaluate muon and neutron fluxes. The results of simulations are compared with experimental data.
Randomised, controlled trial of N-acetylcysteine for treatment of acute exacerbations of chronic obstructive pulmonary disease [ISRCTN21676344]
Peter N Black, Althea Morgan-Day, Tracey E McMillan, Phillippa J Poole, Robert P Young
BMC Pulmonary Medicine , 2004, DOI: 10.1186/1471-2466-4-13
Abstract: We have examined this in a randomised, double-blind, placebo controlled trial. Subjects, admitted to hospital with an acute exacerbation of COPD, were randomised within 24 h of admission to treatment with NAC 600 mg b.d. (n = 25) or matching placebo (n = 25). Treatment continued for 7 days or until discharge (whichever occurred first). To be eligible subjects had to be ≥ 50 years, have an FEV1 ≤ 60% predicted, FEV1/VC ≤ 70% and ≥ 10 pack year smoking history. Subjects with asthma, heart failure, pneumonia and other respiratory diseases were excluded. All subjects received concurrent treatment with prednisone 40 mg/day, nebulised salbutamol 5 mg q.i.d and where appropriate antibiotics. FEV1, VC, SaO2 and breathlessness were measured 2 hours after a dose of nebulised salbutamol, at the same time each day. Breathlessness was measured on a seven point Likert scale.At baseline FEV1 (% predicted) was 22% in the NAC group and 24% in the control group. There was no difference between the groups in the rate of change of FEV1, VC, SaO2 or breathlessness. Nor did the groups differ in the median length of stay in hospital (6 days for both groups).Addition of NAC to treatment with corticosteroids and bronchodilators does not modify the outcome in acute exacerbations of COPD.Exacerbations are an important cause of morbidity in Chronic Obstructive Pulmonary Disease. Seemungal et al found that exacerbations were an important determinant of quality of life in COPD [1]. In addition hospital admissions with exacerbations account for a large proportion of the expenditure on the treatment of COPD [2]. This has led to a search for strategies to prevention exacerbations and to hasten their resolution when they do occur. A systematic review found that treatment with mucolytics for 2 months or more reduced the frequency of exacerbations by 29% [3]. The majority of the studies included in the review were with N-acetylcysteine. These findings are supported by a recent pharmacoepidemiologic st
Origin and evolution of candidate mental retardation genes on the human X chromosome (MRX)
Margaret L Delbridge, Daniel A McMillan, Ruth J Doherty, Janine E Deakin, Jennifer Graves
BMC Genomics , 2008, DOI: 10.1186/1471-2164-9-65
Abstract: To determine if MRX genes were recruited to the X, or whether their brain-specific functions were acquired after relocation to the mammalian X chromosome, we examined the location and expression of their orthologues in marsupials, which diverged from human approximately 180 million years ago. We isolated and mapped nine tammar wallaby MRX homologues, finding that six were located on the tammar wallaby X (which represents the ancient conserved mammal X) and three on chromosome 5, representing the recently added region of the human X chromosome. The location of MRX genes within the same synteny groups in human and wallaby does not support the hypothesis that genes with an important function in the brain were recruited in multiple independent events from autosomes to the mammalian X chromosome. Most of the tammar wallaby MRX homologues were more widely expressed in tammar wallaby than in human. Only one, the tammar wallaby ARX homologue (located on tammar chromosome 5p), has a restricted expression pattern comparable to its pattern in human. The retention of the brain-specific expression of ARX over 180 million years suggests that this gene plays a fundamental role in mammalian brain development and function.Our results suggest all the genes in this study may have originally had more general functions that became more specialised and important in brain function during evolution of humans and other placental mammals.For more than a century, it has been obvious that mental retardation is far more frequent in human males than females, and there have been many claims over the years that inherited mental retardation (MR) syndromes are concentrated on the X chromosome [1,2]. Several well studied X-borne genes have an effect on general cognitive abilities, including FMR1 (fragile X syndrome) and FMR2 (FRAXE mental retardation), as well as a large number of X-linked mental retardation (MRX) syndromes that have been mapped but not cloned and characterised [3]. Attempts to prove
Operational hydrological data assimilation with the recursive ensemble Kalman filter
H. K. McMillan, E. . Hreinsson, M. P. Clark, S. K. Singh, C. Zammit,M. J. Uddstrom
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2013,
Abstract: This paper describes the design and use of a recursive ensemble Kalman filter (REnKF) to assimilate streamflow data in an operational flow forecasting system of seven catchments in New Zealand. The REnKF iteratively updates past and present model states (soil water, aquifer and surface storages), with lags up to the concentration time of the catchment, to improve model initial conditions and hence flow forecasts. We found the REnKF overcame instabilities in the standard EnKF, which were associated with the natural lag time between upstream catchment wetness and flow at the gauging locations. The forecast system performance was correspondingly improved in terms of Nash–Sutcliffe score, persistence index and bounding of the measured flow by the model ensemble. We present descriptions of filter design parameters and explanations and examples of filter behaviour, as an information source for other groups wishing to assimilate discharge observations for operational forecasting.
Exploring the Use of Virtual Worlds as a Scientific Research Platform: The Meta-Institute for Computational Astrophysics (MICA)
S. G. Djorgovski,P. Hut,S. McMillan,E. Vesperini,R. Knop,W. Farr,M. J. Graham
Physics , 2009, DOI: 10.1007/978-3-642-11743-5_3
Abstract: We describe the Meta-Institute for Computational Astrophysics (MICA), the first professional scientific organization based exclusively in virtual worlds (VWs). The goals of MICA are to explore the utility of the emerging VR and VWs technologies for scientific and scholarly work in general, and to facilitate and accelerate their adoption by the scientific research community. MICA itself is an experiment in academic and scientific practices enabled by the immersive VR technologies. We describe the current and planned activities and research directions of MICA, and offer some thoughts as to what the future developments in this arena may be.
Thermal Model Calibration for Minor Planets Observed with WISE/NEOWISE: Comparison with IRAS
A. Mainzer,T. Grav,J. Masiero,J. Bauer,E. Wright,R. M. Cutri,R. Walker,R. S. McMillan
Physics , 2011, DOI: 10.1088/2041-8205/737/1/L9
Abstract: With thermal infrared observations detected by the NEOWISE project, we have measured diameters for 1742 minor planets that were also observed by the Infrared Astronomical Satellite (IRAS). We have compared the diameters and albedo derived by applying a spherical thermal model to the objects detected by NEOWISE and find that they are in generally good agreement with the IRAS values. We have shown that diameters computed from NEOWISE data are often less systematically biased than those found with IRAS. This demonstrates that the NEOWISE dataset can provide accurate physical parameters for the >157,000 minor planets that were detected by NEOWISE.
Energy calibration of large underwater detectors using stopping muons
V. A. Kudryavtsev,R. A. Brook,S. L. Cartwright,J. E. McMillan,N. J. C. Spooner,L. F. Thompson
Physics , 2000, DOI: 10.1016/S0370-2693(00)01219-3
Abstract: We propose to use stopping cosmic-ray muons in the energy calibration of planned and deployed large underwater detectors. The method is based on the proportionality between the incident muon energy and the length of the muon path before it stops. Simultaneous measurements of the muon path and the amplitude of the signal from the photomultiplier tubes allow a relation between the energy deposited in the sensitive volume of the detector and the observed signal to be derived, and also provide a test of detector simulations. We describe the proposed method and present the results of simulations.
Population Genetics of Streptococcus dysgalactiae Subspecies equisimilis Reveals Widely Dispersed Clones and Extensive Recombination
David J. McMillan,Debra E. Bessen,Marcos Pinho,Candace Ford,Gerod S. Hall,José Melo-Cristino,Mário Ramirez
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0011741
Abstract: Streptococcus dysgalactiae subspecies equisimilis (SDSE) is an emerging global pathogen that can colonize and infect humans. Although most SDSE isolates possess the Lancefield group G carbohydrate, a significant minority have the group C carbohydrate. Isolates are further sub-typed on the basis of differences within the emm gene. To gain a better understanding of their molecular epidemiology and evolutionary relationships, multilocus sequence typing (MLST) analysis was performed on SDSE isolates collected from Australia, Europe and North America.
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