Personal nuclear accident dosimetry at Sandia National Laboratories

DOE installations possessing sufficient quantities of fissile material to potentially constitute a critical mass, such that the excessive exposure of personnel to radiation from a nuclear accident is possible, are required to provide nuclear accident dosimetry services. This document describes the personal nuclear accident dosimeter (PNAD) used by SNL and prescribes methodologies to initially screen, and to process PNAD results. In addition, this report describes PNAD dosimetry results obtained during the Nuclear Accident Dosimeter Intercomparison Study (NAD23), held during 12-16 June 1995, at Los Alamos National Laboratories. Biases for reported neutron doses ranged from -6% to +36% with an average bias of +12%

Gauge Dependence of Mass and Condensate in Chirally Asymmetric Phase of Quenched QED3

We study three dimensional quenched Quantum Electrodynamics in the bare vertex approximation. We investigate the gauge dependence of the dynamically generated Euclidean mass of the fermion and the chiral condensate for a wide range of values of the covariant gauge parameter $\xi$. We find that (i) away from $\xi=0$, gauge dependence of the said quantities is considerably reduced without resorting to sophisticated vertex {\em ansatze}, (ii) wavefunction renormalization plays an important role in restoring gauge invariance and (iii) the Ward-Green-Takahashi identity seems to increase the gauge dependence when used in conjunction with some simplifying assumptions. In the Landau gauge, we also verify that our results are in agreement with those based upon dimensional regularization scheme within the numerical accuracy available.Comment: 14 pages, 11 figures, uses revte

Landau-Khalatnikov-Fradkin Transformations and the Fermion Propagator in Quantum Electrodynamics

We study the gauge covariance of the massive fermion propagator in three as well as four dimensional Quantum Electrodynamics (QED). Starting from its value at the lowest order in perturbation theory, we evaluate a non-perturbative expression for it by means of its Landau-Khalatnikov-Fradkin (LKF) transformation. We compare the perturbative expansion of our findings with the known one loop results and observe perfect agreement upto a gauge parameter independent term, a difference permitted by the structure of the LKF transformations.Comment: 9 pages, no figures, uses revte

Physical activity opportunities within the schedule of early care and education centers

Background: Physical activity has many benefits for young children's health and overall development, but few studies have investigated how early care and education centers allot time for physical activity, along with measured individual physical activity levels for indoor/outdoor activities during a typical day. Methods: Fifty early care and education centers in central North Carolina participated in 4 full-day observations, and 559 children aged 3-5 years within centers wore accelerometers assessing physical activity during observation days. Observation and physical activity data were linked and analyzed for associations between child activity and type of classroom activity. Results: Children averaged 51 (13) minutes per day of moderate to vigorous physical activity and 99 (18) minutes per day of light physical activity while in child care. Children averaged 6 (10) and 10 (13) minutes per day of observed outdoor and indoor daily teacher-led physical activity, respectively. Outdoor time averaged 67 (49) minutes per day, and physical activity levels were higher during outdoor time than during common indoor activities (center time, circle time, and TV time). Conclusions: Physical activity levels varied between indoor and outdoor class activities. Policy and program-related efforts to increase physical activity in preschoolers should consider these patterns to leverage opportunities to optimize physical activity within early care and education centers

Global patterns of nitrate storage in the vadose zone

Global-scale nitrogen budgets developed to quantify anthropogenic impacts on the nitrogen cycle do not explicitly consider nitrate stored in the vadose zone. Here we show that the vadose zone is an important store of nitrate that should be considered in future budgets for effective policymaking. Using estimates of groundwater depth and nitrate leaching for 1900–2000, we quantify the peak global storage of nitrate in the vadose zone as 605–1814 Teragrams (Tg). Estimates of nitrate storage are validated using basin-scale and national-scale estimates and observed groundwater nitrate data. Nitrate storage per unit area is greatest in North America, China and Europe where there are thick vadose zones and extensive historical agriculture. In these areas, long travel times in the vadose zone may delay the impact of changes in agricultural practices on groundwater quality. We argue that in these areas use of conventional nitrogen budget approaches is inappropriate

Renormalization and Chiral Symmetry Breaking in Quenched QED in Arbitrary Covariant Gauge

We extend a previous Landau-gauge study of subtractive renormalization of the fermion propagator Dyson-Schwinger equation (DSE) in strong-coupling, quenched QED_4 to arbitrary covariant gauges. We use the fermion-photon proper vertex proposed by Curtis and Pennington with an additional correction term included to compensate for the small gauge-dependence induced by the ultraviolet regulator. We discuss the chiral limit and the onset of dynamical chiral symmetry breaking in the presence of nonperturbative renormalization. We extract the critical coupling in several different gauges and find evidence of a small residual gauge-dependence in this quantity.Comment: REVTEX 3.0, 27 pages including 14 Extended Postscript files comprising 9 figures. Replacement: discussion of chiral limit corrected, and some minor typographical errors fixed. To appear in Phys. Rev.

Driving pro-environmental change in tourist destinations: encouraging sustainable travel in National Parks via partnership project creation and implementation

© 2016 Taylor & Francis. This paper explores a key challenge in introducing more sustainable transport practices at destinations: achieving modal shift in visitor travel from cars to physically active or public transport to reduce tourism's environmental impacts. It centres on using partnership led projects bringing together the many public and private sector organisations involved, to drive destination change and development. To date, research has centred on pro-environmental change for individuals and individual organisations: little is known about the mechanisms of pro-environmental change via complex multi-partner organisations. The paper reports research into the processes involved in successful projects to provide alternatives to car travel in three UK National Parks by using partnerships to obtain funding and implement change. Based on case studies informed by in-depth interviews with key stakeholders involved in pro-environmental change implementation, narratives are analysed to explain the change process, and mapped against existing literature and theories of change. Conclusions show the role of inspired individuals, supportive senior management, strong governance, better visitor experiences and, most significantly, communication and communication of the benefits of change to stakeholders. The research suggests why and how change occurs in partnerships, contributes to better theories of change and offers guidance on understanding and implementing change processes worldwide