The Use of Aerial Radiometrics for Epidemiological Studies of Leukaemia: a Preliminary Investigation in SW England

The report presents the results and conclusions of a pilot study designed to evaluate the potential use of aerial gamma ray measurements in epidemiological investigations of leukaemia. The sources of natural radiation were reviewed and associations between U, Th and K and dose to the human population noted. The association between leukaemia and radiation exposure was also noted, in particular the clear evidence from high dose studies, the potential importance of radium and radon, and the difficulties of achieving statistical significance in case-control studies at environmental dose rates due to the need for large area surveys covering large populations. Aerial surveys were conducted in three disjoint grids selected by the Leukaemia Research Fund Clinical epidemiology unit at Leeds University. The areas covered some 2,500 km, and were surveyed in a 50 hour fieldwork period in September 1989. Over 4800 gamma spectra were recorded, representing between 200 and 400 times the number of measurements per unit area of the NRPB national maps, and an area sampling density some 106 times greater. The data were used to estimate specific activities of potassium, uranium and thorium. Environmental infinite matrix alpha and beta dose rates were calculated using equilibrium assumptions and gamma ray dose rates were estimated directly from the spectra. Mean values for gamma dose rates were compatible with NRPB estimates for the counties. The detailed gamma ray maps demonstrate that both radiation levels, and quality show local variations within each survey grid of a magnitude comparable with that observed in whole of the UK in national maps. Considerable caution is thus needed in using national data for epidemiological studies. Local variations, which can be clearly associated with underlying geological and geomorphological structures should be taken into account in such work. No significant enhancements were noted due to activities at the Devonport Dockyard, in keeping with published ground based monitoring. The main enhancement in the vicinity of Hinkley Point was due to the authorised discharge of 41Ar, which was clearly detected in the survey. Two methods for associating the radiometric results with epidemiological data were developed and applied. A case-control study was performed by matching case and control locations to individual spatially averaged radiometric results and comparing the associated radiation levels. The second method evaluated radiation stratified incidence rates by combining stratified case radiometric data with similar information estimated from a population density surface constructed for the grids. Weighted regression analysis was used to assess any associations. The results are in general limited by the low number of leukaemia cases within the study area, resulting in statistically weak or insignificant links. However positive associations between equivalent uranium and leukaemia, particularly in the grid including the rivers Tavy and Tamar, were observed in both case-control and incidence rate analyses. A negative association with equivalent Thorium observed in the incidence rate analysis was not reproduced in case-control comparisons. This approach could be extended to larger area studies to increase statistical power. In parallel investigations of the relationship between environmental and individual radiation exposure, and investigation of the potential association between radium, or radon and leukaemia following the trends observed here would be appropriate

NLO prescription for unintegrated parton distributions

We show how parton distributions unintegrated over the parton transverse momentum, k_t, may be generated, at NLO accuracy, from the known integrated (DGLAP-evolved) parton densities determined from global data analyses. A few numerical examples are given, which demonstrate that sufficient accuracy is obtained by keeping only the LO splitting functions together with the NLO integrated parton densities. However, it is important to keep the precise kinematics of the process, by taking the scale to be the virtuality rather than the transverse momentum, in order to be consistent with the calculation of the NLO splitting functions.Comment: 20 pages, 8 figures. v2: version to appear in Eur. Phys. J.

Field-Induced Magnetization Steps in Intermetallic Compounds and Manganese Oxides: The Martensitic Scenario

Field-induced magnetization jumps with similar characteristics are observed at low temperature for the intermetallic germanide Gd5Ge4and the mixed-valent manganite Pr0.6Ca0.4Mn0.96Ga0.04O3. We report that the field location -and even the existence- of these jumps depends critically on the magnetic field sweep rate used to record the data. It is proposed that, for both compounds, the martensitic character of their antiferromagnetic-to-ferromagnetic transitions is at the origin of the magnetization steps.Comment: 4 pages,4 figure

Glauber - Gribov approach for DIS on nuclei in N=4 SYM

In this paper the Glauber-Gribov approach for deep-inelastic scattering (DIS) with nuclei is developed in N=4 SYM. It is shown that the amplitude displays the same general properties, such as geometrical scaling, as is the case in the high density QCD approach. We found that the quantum effects leading to the graviton reggeization, give rise to an imaginary part of the nucleon amplitude, which makes the DIS in N=4 SYM almost identical to the one expected in high density QCD. We concluded that the impact parameter dependence of the nucleon amplitude is very essential for N=4 SYM, and the entire kinematic region can be divided into three regions which are discussed in the paper. We revisited the dipole description for DIS and proposed a new renormalized Lagrangian for the shock wave formalism which reproduces the Glauber-Gribov approach in a certain kinematic region. However the saturation momentum turns out to be independent of energy, as it has been discussed by Albacete, Kovchegov and Taliotis. We discuss the physical meaning of such a saturation momentum $Q_s(A)$ and argue that one can consider only $Q>Q_s(A)$ within the shock wave approximation.Comment: 40pp.,9 figures in eps file

One size fits ball: Macrocyclic hosts for fullerenes with micromolar affinity

Date du colloque : 25/03/2012International audienc

Charge and Current Sum Rules in Quantum Media Coupled to Radiation

This paper concerns the equilibrium bulk charge and current density correlation functions in quantum media, conductors and dielectrics, fully coupled to the radiation (the retarded regime). A sequence of static and time-dependent sum rules, which fix the values of certain moments of the charge and current density correlation functions, is obtained by using Rytov's fluctuational electrodynamics. A technique is developed to extract the classical and purely quantum-mechanical parts of these sum rules. The sum rules are critically tested in the classical limit and on the jellium model. A comparison is made with microscopic approaches to systems of particles interacting through Coulomb forces only (the non-retarded regime). In contrast with microscopic results, the current-current correlation function is found to be integrable in space, in both classical and quantum regimes.Comment: 19 pages, 1 figur

The small x gluon and b\bar{b} production at the LHC

We study open b\bar{b} production at large rapidity at the LHC in an attempt to pin down the gluon distribution at very low x. For the LHC energy of 7 TeV, at next-to-leading order (NLO), there is a large factorization scale uncertainty. We show that the uncertainty can be greatly reduced if events are selected in which the transverse momenta of the two B-mesons balance each other to some accuracy, that is |\vec p_{1T}+\vec p_{2T}| < k_0. This will fix the scale \mu_F \simeq k_0, and will allow the LHCb experiment, in particular, to study the x-behaviour of gluon distribution down to x ~ 10^{-5}, at rather low scales, \mu ~ 2 GeV. We evaluate the expected cross sections using, for illustrative purposes, various recent sets of Parton Distribution Functions.Comment: 13 pages, 5 figure