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Erratum to “Evaluation of a Suspended Personal Radiation Protection System vs. Conventional Apron and Shields in Clinical Interventional Procedures” [Open Journal of Radiology 3 (2013) 143-151]  [PDF]
Chet R. Rees
Open Journal of Radiology (OJRad) , 2017, DOI: 10.4236/ojrad.2017.74027
Abstract: The original online version of this article (C. Savage, T. Seale IV, C. Shaw, B. Angela, D. Marichal and C. Rees, “Evaluation of a Suspended Personal Radiation Protection System vs. Conventional Apron and Shields in Clinical Interventional Procedures,” Open Journal of Radilogy, 3, 143-151. http://dx.doi.org/10.4236/ojrad.2013.33024) was mistaken of the total isolates number in Table 2. The authors wish to correct the errors to: Table 2. Other study parameters “Gycm2” should be changed to “cGycm2” All of the decimal points (“.”) should be changed to commas (“,”). For example, “47.486” should be “47,486”.
Evaluation of a Suspended Personal Radiation Protection System vs. Conventional Apron and Shields in Clinical Interventional Procedures  [PDF]
Clare Savage, Thomas M. Seale IV, Cathryn J. Shaw, Bruner P. Angela, Daniel Marichal, Chet R. Rees
Open Journal of Radiology (OJRad) , 2013, DOI: 10.4236/ojrad.2013.33024
Abstract:

Purpose: This clinical study compares conventional lead aprons and ancillary shields to a functionally weightless personal overhead-supported system with expanded coverage. Materials and Methods: Primary operators performed procedures (N = 126, fluoroscopy minutes = 1209) using one of 2 methods of radiation protection and wearing dosimeters on multiple body locations. Method “LAS” (Lead-Apron+Shields): lead skirt, vest, thyroid shield, with 100% use of under-table shield, side shield, and mobile suspended lead-acrylic shield. Method “Zgrav”: ZeroGravity system (CFI Medical Solutions) with variable use of shielding. The studied early model moving with the operator had a curved lead-acrylic head shield (0.5 mm Pb) and expansive lead apron (0.5 - 1.0 mm Pb) that covered leg to distal calf and proximal arm to elbow, and a drape that permitted sterile entry and exit. Study was institutional review board approved and HIPPA-compliant. Results: Measured with a sensitive electronic dosimeter, eye exposures were 99% (P < 0.001) reduced for Zgrav with upgraded face shield vs. LAS, regardless of use or non-use of suspended shield with Zgrav. With optically stimulated luminescence (OSL) dosimeters, operator exposures, standardized to minutes of fluoroscopy and Fluoroscopic Patient Dose Area Product, were reduced by 87%

Viewing Angle and Environment Effects in GRB: Sources of Afterglow Diversity
P. Meszaros,M. J. Rees,R. A. M. J. Wijers
Physics , 1997, DOI: 10.1086/305635
Abstract: We discuss the afterglows from the evolution of both spherical and anisotropic fireballs decelerating in an inhomogeneous external medium. We consider both the radiative and adiabatic evolution regimes, and analyze the physical conditions under which these regimes can be used. Afterglows may be expected to differ widely among themselves, depending on the angular anisotropy of the fireball and the properties of the environment. They may be entirely absent, or may be detected without a corresponding $\gamma$-ray event. A tabulation of different representative light curves is presented, covering a wide range of behaviors that resemble what is currently observed in GRB 970228, GRB 970508 and other objects.
Energetics and beaming of gamma-ray burst triggers
P. Meszaros,M. J. Rees,R. A. M. J. Wijers
Physics , 1998, DOI: 10.1016/S1384-1076(99)00013-5
Abstract: A wide range of mechanisms have been proposed to supply the energy for gamma-ray bursts (GRB) at cosmological distances. It is a common misconception that some of these, notably NS-NS mergers, cannot meet the energy requirements suggested by recent observations. We show here that GRB energies, even at the most distant redshifts detected, are compatible with current binary merger or collapse scenarios involving compact objects. This is especially so if, as expected, there is a moderate amount of beaming, since current observations constrain the energy per solid angle much more strongly and directly than the total energy. All plausible progenitors, ranging from NS-NS mergers to various hypernova-like scenarios, eventually lead to the formation of a black hole with a debris torus around it, so that the extractable energy is of the same order, 1E+54 ergs, in all cases. MHD conversion of gravitational into kinetic and radiation energy can significantly increase the probability of observing large photon fluxes, although significant collimation may achieve the same effect with neutrino annihilation in short bursts. The lifetime of the debris torus is dictated by a variety of physical processes, such as viscous accretion and various instabilities; these mechanisms dominate at different stages in the evolution of the torus and provide for a range of gamma-ray burst lifetimes.
Nitrous oxide emissions from European agriculture; an analysis of variability and drivers of emissions from field experiments
R. M. Rees,J. Augustin,G. Alberti,B. C. Ball
Biogeosciences Discussions , 2012, DOI: 10.5194/bgd-9-9259-2012
Abstract: Nitrous oxide emissions from a network of agricultural experiments in Europe and Zimbabwe were used to explore the relative importance of site and management controls of emissions. At each site, a selection of management interventions were compared within replicated experimental designs in plot based experiments. Arable experiments were conducted at Beano in Italy, El Encin in Spain, Foulum in Denmark, Log rden in Sweden, Maulde in Belgium, Paulinenaue in Germany, Harare in Zimbabwe and Tulloch in the UK. Grassland experiments were conducted at Crichton, Nafferton and Peaknaze in the UK, G d ll in Hungary, Rzecin in Poland, Zarnekow in Germany and Theix in France. Nitrous oxide emissions were measured at each site over a period of at least two years using static chambers. Emissions varied widely between sites and as a result of manipulation treatments. Average site emissions (throughout the study period) varied between 0.04 and 21.21 kg N2O-N ha 1 yr 1, with the largest fluxes and variability associated with the grassland sites. Total nitrogen addition was found to be the single most important determinant of emissions, accounting for 15% of the variance (using linear regression) in the data from the arable sites (p < 0.0001), and 77% in the grassland sites. The annual emissions from arable sites were significantly greater than those that would be predicted by IPCC default emission factors. Variability in N2O within sites that occurred as a result of manipulation treatments was greater than that resulting from site to site and year to year variation, highlighting the importance of management interventions in contributing to greenhouse gas mitigation.
Spatio-temporal development of streamflow droughts in north-west Europe
M. D. Zaidman,H. G. Rees,A. R. Young
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2002,
Abstract: This paper examines the spatial and temporal development of streamflow droughts in Europe over the last 40 years, differentiating the climatic factors that drive drought formation from catchment controls on drought manifestation. A novel approach for quantifying and comparing streamflow and precipitation depletion is presented. This approach considers atypical flow or rainfall events, as well as more severe droughts, regardless of the season in which they occur (although unlikely to constitute drought in an operational sense, sustained atypical flows are important with regard to understanding how droughts arise and develop). The amount of flow depletion is quantified at daily resolution based on the standardised departure from the mean day d flow, or flow anomaly. The index was derived for 2780 gauging points within north-west Europe using data from the FRIEND European Water Archive for the 1960-1995 period. Using a simple interpolation procedure these data were used to produce a time-series of grids, with a cell size of 18 km2, showing the spatial distribution of flow anomaly over the study area. A similar approach was used to characterise monthly precipitation anomalies, based on existing grid data (see New et al., 2000). The grids were analysed chronologically to examine the spatial and temporal coherency of areas showing large flow and/or precipitation anomalies, focussing on drought development during the 1975-1976 and 1989-1990 periods. Using a threshold approach, in which an anomaly of 2 standard deviations represents the onset of drought conditions, indices were developed to describe the time-varying extent and areal-severity (flow deficit) of streamflow and precipitation drought. Similar indices were used to describe how the magnitude and temporal variation of flow depletion varied spatially. In terms of streamflow depletion, the 1976 drought was found to be a highly coherent event, having a well defined start (in January 1976) and end (in September 1976). The worst and most persistent streamflow droughts occurred in southern England and northern France. Central parts of Europe experienced only severe streamflow depletion during the ‘height’ of the drought in June, July and August when there was negligible precipitation across large areas of Europe. In contrast, the 1989/90 period was characterised by a series of shorter and less severe droughts, with much greater variability over time. The relationship between precipitation drought and streamflow drought was less clear, which might have resulted from periods of precipitation depletion occurrin
Iron K Lines from Gamma Ray Bursts
T. R. Kallman,P. Meszaros,M. J. Rees
Physics , 2001, DOI: 10.1086/376676
Abstract: We present models for reprocessing of an intense flux of X-rays and gamma rays expected in the vicinity of gamma ray burst sources. We consider the transfer and reprocessing of the energetic photons into observable features in the X-ray band, notably the K lines of iron. Our models are based on the assumption that the gas is sufficiently dense to allow the microphysical processes to be in a steady state, thus allowing efficient line emission with modest reprocessing mass and elemental abundances ranging from solar to moderately enriched. We show that the reprocessing is enhanced by down-Comptonization of photons whose energy would otherwise be too high to absorb on iron, and that pair production can have an effect on enhancing the line production. Both "distant" reprocessors such as supernova or wind remnants and "nearby" reprocessors such as outer stellar envelopes can reproduce the observed line fluxes with Fe abundances 30-100 times above solar, depending on the incidence angle. The high incidence angles required arise naturally only in nearby models, which for plausible values can reach Fe line to continuum ratios close to the reported values.
A historical and proteomic analysis of botulinum neurotoxin type/G
Rebecca R Terilli, Hercules Moura, Adrian R Woolfitt, Jon Rees, David M Schieltz, John R Barr
BMC Microbiology , 2011, DOI: 10.1186/1471-2180-11-232
Abstract: An in-depth comparison of protein sequences indicated that BoNT/G shares the most sequence similarity with the/B serotype. A temperature-modified Endopep-MS activity assay was successful in the detection of BoNT/G activity. Gel electrophoresis and in gel digestions, followed by MS/MS analysis of/G complex, revealed the presence of four proteins in the complexes: neurotoxin (BoNT) and three NAPs--nontoxic-nonhemagglutinin (NTNH) and two hemagglutinins (HA70 and HA17). Rapid high-temperature in-solution tryptic digestions, coupled with MS/MS analysis, generated higher than previously reported sequence coverages for all proteins associated with the complex: BoNT 66%, NTNH 57%, HA70 91%, and HA17 99%. Label-free relative quantification determined that the complex contains 30% BoNT, 38% NTNH, 28% HA70, and 4% HA17 by weight comparison and 17% BoNT, 23% NTNH, 42% HA70, and 17% HA17 by molecular comparison.The in silico protein sequence comparisons established that the/G complex is phenetically related to the other six serotypes of C. botulinum. Proteomic analyses and Endopep-MS confirmed the presence of BoNT and NAPs, along with the activity of the commercial/G complex. The use of data-independent MSE data analysis, coupled to label-free quantification software, suggested that the weight ratio BoNT:NAPs is 1:3, whereas the molar ratio of BoNT:NTNH:HA70:HA17 is 1:1:2:1, within the BoNT/G progenitor toxin.Clostridium botulinum is the taxonomic designation for at least six diverse species that produce botulinum neurotoxins (BoNTs). This heterologous species is further classified into six metabolically distinct groups (I-VI). The groups include the toxin-forming strains of C. botulinum, C. butyricum, C. baratii, and C. argentinense [1]. C. botulinum is a spore-forming anaerobic bacteria which produces toxins that are lethal to humans and animals, and are classified as category A bioterrorism agents [2,3]. BoNTs target the Soluble NSF Attachment Protein Receptors (SNARE) compl
Recession-based hydrological models for estimating low flows in ungauged catchments in the Himalayas
H. G. Rees,M. G. R. Holmes,A. R. Young,S. R. Kansakar
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2004,
Abstract: The Himalayan region of Nepal and northern India experiences hydrological extremes from monsoonal floods during July to September, when most of the annual precipitation falls, to periods of very low flows during the dry season (December to February). While the monsoon floods cause acute disasters such as loss of human life and property, mudslides and infrastructure damage, the lack of water during the dry season has a chronic impact on the lives of local people. The management of water resources in the region is hampered by relatively sparse hydrometerological networks and consequently, many resource assessments are required in catchments where no measurements exist. A hydrological model for estimating dry season flows in ungauged catchments, based on recession curve behaviour, has been developed to address this problem. Observed flows were fitted to a second order storage model to enable average annual recession behaviour to be examined. Regionalised models were developed, using a calibration set of 26 catchments, to predict three recession curve parameters: the storage constant; the initial recession flow and the start date of the recession. Relationships were identified between: the storage constant and catchment area; the initial recession flow and elevation (acting as a surrogate for rainfall); and the start date of the recession and geographic location. An independent set of 13 catchments was used to evaluate the robustness of the models. The regional models predicted the average volume of water in an annual recession period (1st of October to the 1st of February) with an average error of 8%, while mid-January flows were predicted to within ±50% for 79% of the catchments in the data set. Keywords: Himalaya, recession curve, water resources, ungauged catchment, regionalisation, low flows
The age of Taurus - environmental effects on disc lifetimes
Jon M. Rees,T. Wilson,C. P. M. Bell,R. D. Jeffries,Tim Naylor
Physics , 2015,
Abstract: Using semi-empirical isochrones, we find the age of the Taurus star-forming region to be 3-4 Myr. Comparing the disc fraction in Taurus to young massive clusters suggests discs survive longer in this low density environment. We also present a method of photometrically de-reddening young stars using $iZJH$ data.
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