Assessment of soil radon potential in Hong Kong, China, using a 10-point evaluation system

Radon and its progenies have been ranked second of being responsible for lung cancer in humans. Hong Kong has four major groups of uranium-rich plutonic and volcanic rocks and is suffering from radon emanated therefrom. However, there is a lack of radon potential maps in Hong Kong to resolve the spatial distribution of radon-prone areas. A ten-point radon potential system was developed in Germany (2005) to predict radon potential using both the in situ geogenic and geographic parameters under hierarchical ranking. Primarily, the ten-point system requires the desk study of the geological environment of sampling sites, which has an advantage of saving resources and manpower in extensive radon potential mapping over the traditional soil radon concentration sampling method. This paper presents a trial of radon potential mapping in Hong Kong to further verify the system. Despite some slight departures, the system demonstrates an acceptable correlation with soil radon concentrations (R 2 = 0.62-0.66) from 768 samples of mainly intermediate radon potential. Hong Kong has a mean soil radon concentrations of 58.9 kBqm -3, while the radon potential from the ten-point system achieves an average of 4.93 out of 10 over the territory. The vicinity of fault zone showed high soil radon concentrations and potentials, which were conducive to uranium enrichment and rapid soil-gas diffusion near faults. High uranium-238 content in soil was found to cause high soil radon concentration with a large R 2, 0.84. The Jurassic granite and volcanic crystal tuff cover more than 85 % of the whole Hong Kong area, and they show relatively high radon concentrations (Geometric mean 83 and 49 kBqm -3, respectively) which are associated with their high uranium contents (Geometric mean 234 and 197 Bqkg -1, respectively). While indoor radon concentration is an important factor for radon risk assessment, this study has not considered the correlation between indoor radon concentration and radon potential. The reason is that almost all buildings in Hong Kong are high-rise buildings where indoor radon concentrations are governed only by the radium content in the building materials and the ventilation conditions. © 2012 The Author(s).published_or_final_versio

The influence of coal mining on radon potential

Pit waters from hard-coal and brown-coal mining as well as sediments and soils along sewers and rivers in the vicinity of collieries are investigated in the scope of radiation protection. The greatest amount of 226Ra is discharged by hard-coal collieries in the order of several ten Bq l21 at simultaneous occurrence of high mineralised brines. In contact with sulphate-bearing surface water, 226Ra co-precipitates with Ba and is deposited as radiobarite. The contamination with 226Ra leads to high activity concentrations and increased gamma dose rates. The special situation of diadochic incorporation of 226Ra into the dense crystal lattice prevents 222Rn from emanating. However in sediments influenced by brown-coal mining 226Ra is adsorbed at the surfaces of ferric hydroxides and, therefore, 222Rn can easily emanate

Seismic waves in the urban environment triggering radon release from the soil

The influence of anthropogenic induced seismic waves on the radon potential is analysed in this study. The influence is determined near railway tracks, heavy traffic roads and on project sites. Generally, the radon concentration in soil gas increases due to vibrations, but the type of vibrations has a pronounced influence on the amount of increase. The spatial radius of radon increase is highest on project sites (D60 m). Along railway tracks the radius is wider (D30 m) than along heavy traffic roads (E25 m). The increase can be explained by a “pump effect”. That means that mechanical vibrations of mineral particles lead to an upward movement of the entire volume of soil gas. In the course of continuing vibrations the topmost layers lose radon to the atmosphere and as a result the upward transport of radon is increased. By this process radon can be pumped into houses, where it can accumulate

Finite element study of the accommodation behaviour of the crystalline lens after fs-laser treatment

With aging the ability of the crystalline lens to adapt to different viewing distances decreases. Until now there is no satisfying treatment available. It is possible to influence the deformability of the crystalline lens by inducing cuts using femtosecond (fs)-laser. To test the influence of several different cutting geometries is expensive and a huge amount of crystalline lenses is needed. Finit Element Method offers the possibility to test the influence of different cutting geometries on the flexibility. Therefore, it is necessary to develop a method to simulate the cuts in an adequate way. In first simulations cuts were assumed to be isotropic inter layers. Later on, effective material properties for the inter layer were calculated with a homogenization technique. The results confirm the influence of the cuts on the flexibility.DFG/BE3990-

A visual demonstration of convergence properties of cooperative coevolution

We introduce a model for cooperative coevolutionary algorithms (CCEAs) using partial mixing, which allows us to compute the expected long-run convergence of such algorithms when individuals ’ fitness is based on the maximum payoff of some N evaluations with partners chosen at random from the other population. Using this model, we devise novel visualization mechanisms to attempt to qualitatively explain a difficult-to-conceptualize pathology in CCEAs: the tendency for them to converge to suboptimal Nash equilibria. We further demonstrate visually how increasing the size of N, or biasing the fitness to include an ideal-collaboration factor, both improve the likelihood of optimal convergence, and under which initial population configurations they are not much help

Color, Marbling, and Firmness Characteristics of Fresh Hams from Barrows Supplemented with Conjugated Linoleic Acid

This study is a part of a continuing research project investigating the feeding of conjugated linoleic acid (CLA) to market pigs to achieve improvements in carcass growth and pork-quality characteristics. The CLA was fed at a constant level (0.75%) from 40 kg to 115 kg of body weight. This resulted in an increase in subjective uniformity, color, marbling, and tended to increase objective L* values of hams from pigs supplemented with CLA compared with hams that were from pigs fed a control diet. No treatment differences were observed for pH, ham weight, firmness, and Hunter a* and b* values. This report will focus on the subjective and objective quality and compositional characteristics of fresh pork hams form CLAsupplemented pigs. Pigs supplemented CLA in finishing diets had as high ham quality as controls. Therefore, CLA would be beneficial in swine diets

Intraocular retinal transplants

Embryonic rat retinae transplanted into the anterior chamber of adult rat eyes of the same or different strain survive and grow. Light and electron microscopic studies show that the transplants undergo histogenetic differentiation, resulting in the development of mature inner and outer layer neurons and Muller glial cells. Vascular connections develop between the host iris and the retinal transplant. These initial observations indicate that retinal transplantation to a recipient eye is a procedure which offers ample opportunities for the study of problems related to neural development, retinal plasticity and repair