Precautions for Workers

Radioactive isotopes are now available from Chalk River for use by Canadian biologists. Experience has shown that the handling of radioactive isotopes may involve health hazards unless adequate precautions are taken. The nature of these hazards and the type of precautions which must be taken when working with radioactive isotopes are considered. Successful work with radioactive isotopes other than in the smallest tracer amounts requires the use of laboratories and equipment especially designed for the purpose and this is dealt with briefly. The operation of a radioactive laboratory requires certain auxiliary equipment and services, such as health instruments, film monitoring, special laboratory clothing, special cleanable surfaces and disposal of radioactive waste materials. These topics are discussed briefly. Handling of radioactive isotopes involves certain special precautions and a few of these, such as protection of hands, cleaning of glassware, handling of solutions, etc. are reviewed. In addition to protecting all personnel in a laboratory from harmful amounts of radiation, it is necessary to keep the laboratory and the building in which it is housed as free as possible from radioactive substances and this important fact has been stressed.     

Development of a modified cortisol extraction procedure for intermediately sized fish not amenable to whole-body or plasma extraction methods

The corticosteroid hormone cortisol is the central mediator of the teleost stress response. Therefore, the accurate quantification of cortisol in teleost fishes is a vital tool for addressing fundamental questions about an animal’s physiological response to environmental stressors. Conventional steroid extraction methods using plasma or whole-body homogenates, however, are inefficient within an intermediate size range of fish that are too small for phlebotomy and too large for whole-body steroid extractions. To assess the potential effects of hatchery-induced stress on survival of fingerling hatchery-reared Spotted Seatrout (Cynoscion nebulosus), we developed a novel extraction procedure for measuring cortisol in intermediately sized fish (50–100 mm in length) that are not amenable to standard cortisol extraction methods. By excising a standardized portion of the caudal peduncle, this tissue extraction procedure allows for a small portion of a larger fish to be sampled for cortisol, while minimizing the potential interference from lipids that may be extracted using whole-body homogenization procedures. Assay precision was comparable to published plasma and whole-body extraction procedures, and cortisol quantification over a wide range of sample dilutions displayed parallelism versus assay standards. Intra-assay  %CV was 8.54 %, and average recovery of spiked samples was 102 %. Also, tissue cortisol levels quantified using this method increase 30 min after handling stress and are significantly correlated with blood values. We conclude that this modified cortisol extraction procedure provides an excellent alternative to plasma and whole-body extraction procedures for intermediately sized fish, and will facilitate the efficient assessment of cortisol in a variety of situations ranging from basic laboratory research to industrial and field-based environmental health applications.     

Soil and sediment quality and composition as factors in the distribution of damage at the December 26, 2003, Bam area earthquake in SE Iran (M s = 6.6)

Background, aim, and scope

The rapid growth of the world’s population over the past few decades has led to a concentration of people, buildings, and infrastructure in urban areas. The tendency of urban areas to develop in sedimentary valleys has increased their vulnerability to earthquakes due to the presence of soft soil and sediment. Several earthquakes have clearly demonstrated that local soil and sediment conditions can have a significant influence on earthquake-induced ground motion and damage pattern, respectively. Many studies confirm the relationship between site effect and ground motion (Borcherdt in Bull Seismol Soc Am 60:29–61, 1970; Bouckovalas et al. in Geotech Geolog Eng (Historical Archive) 14(2):111–128, 1996; Fäh et al. in Seismology 1:87–10, 1997; Atakan et al. in Nat Hazards 15(2–3):139–164, 1997; Christaras et al. in Geodynamics 26(2–4):393–411, 1998; Raptakis et al. in Bull Earthquake Eng 2(3):285–301, 2004a; Raptakis et al. in Soil Dyn Earthq Eng 25:871–887, 2005; Marka et al. in Pure Appl Geophys 158:2349–2367, 2001; Marka et al. in Soil Dyn Earthq Eng 25(4):303–315, 2005; Importa et al. in Seismology 9(2):191–210, 2005; Tyagunov et al. in Nat Hazards 38:199–214, 2006; Lombardo et al. in Nat Hazards 38:339–354, 2006; Rayhani et al. in Geotech Geol Eng 21(1):91–100, 2008). In order to classify the suitability of the soil and subsurface sediment units for urban planning and compare their mechanical behavior with the non-uniform damage observed in the 2003 earthquake, we performed some geotechnical and geophysical analyses of soil and sediment samples collected from different locations in Bam City.

Methodology

Geophysical and geotechnical properties, such as grain size distribution, sorting, plasticity, Poison’s ratio, shear strength, compression index, permeability, and P and S wave velocities in soil and subsurface sediments, were measured. Maps (in GIS environment) and cross-sections were prepared for the study area.

Results

According to our observations, a great number of buildings were damaged in areas of the city where silty and clayey soils dominate, presenting very low permeability, low wave velocity together with high plasticity, and compressibility. In the study area, we recognized eight sediment types. Shear wave propagation velocities allowed for the identification of four seismic layers referred to as the surface layer, second layer, and third layer and seismic bedrock. We found that the damages observed in the Bam area were related to the physical and mechanical properties of the soil and subsurface sediment units. We also found that the soil thickness that was estimated by geophysical surveying shows a direct relationship with damage rate observations. Furthermore, we observed that landslide and qanat collapses have occurred in some areas where sand and silty sand soils and subsurface sediments dominate.

Discussion

The distribution of the damage shows a microzonation that is very serious in some points in the city along the main fault, especially where it is located on thick, fine, medium, and loose soil and sediments. In general, there is a discernable west to east increase in the damage across the city. The average level of destruction for the entire city was ~75%, while the eastern part of the city locally reached 100% destruction level. The major factors that influenced the damage and destruction in the Bam region were the distance of a given site from the seismic source, the quality of foundation soil and subsurface sediment, and the type of building. The Bam earthquake occurred on a single fault network comprising the Bam and Arg-e-Bam faults (Funning et al. in J Geophys Res 100(B09406):1–23, 2005). The sediments and soil of the area (unconsolidated silty sand and sandy gravel) belong to braided fluvial and alluvial facies. Most of the buildings near the epicenter area were old and constructed of mud bricks using mud cement.

Recommendations and perspectives

A combined sedimentological, geological, neotectonic, geotechnical, paleoseismological, and geophysical investigation in urban areas (especially in alluvial valleys) will give the detailed knowledge of the subsurface structure required for the accurate and precise seismic hazard assessments needed for effective earthquake protection planning. This paper shows that for the Bam situation, sedimentological data are required to provide an interpretive context for the geophysical data.     

Black pod: diverse pathogens with a global impact on cocoa yield

ABSTRACT Pathogens of the Straminipile genus Phytophthora cause significant disease losses to global cocoa production. P. megakarya causes significant pod rot and losses due to canker in West Africa, whereas P. capsici and P. citrophthora cause pod rots in Central and South America. The global and highly damaging P. palmivora attacks all parts of the cocoa tree at all stages of the growing cycle. This pathogen causes 20 to 30% pod losses through black pod rot, and kills up to 10% of trees annually through stem cankers. P. palmivora has a complex disease cycle involving several sources of primary inoculum and several modes of dissemination of secondary inoculum. This results in explosive epidemics during favorable environmental conditions. The spread of regional pathogens must be prevented by effective quarantine barriers. Resistance to all these Phytophthora species is typically low in commercial cocoa genotypes. Disease losses can be reduced through integrated management practices that include pruning and shade management, leaf mulching, regular and complete harvesting, sanitation and pod case disposal, appropriate fertilizer application and targeted fungicide use. Packaging these options to improve uptake by smallholders presents a major challenge for the industry.     

Prevalence of Campylobacter and four endoparasites in dog populations associated with Hearing Dogs

OBJECTIVES: This study established the prevalence of four gastrointestinal parasites (Isopora species, Giardia species, Uncinaria stenocephala, Toxocara canis) and one bacterial infection (Campylobacter jejuni/coli) in dogs associated with the charity Hearing Dogs for Deaf People. METHODS: Dogs' faeces were routinely sampled from dogs according to whether they were in Socialising, Kennelling or Visiting the Hearing Dogs site. A further group consisted of dogs with diarrhoea. RESULTS: Prevalence rates for dogs in Socialising (n=326), Kennelling (n=117), Visiting (n=106) and Diarrhoea (n=59) groups, respectively, were as follows: Campylobacter- 26, 21, 15 and 31 per cent; Coccidia - 3, 0, 0 and 2 per cent; Giardia- 13, 3, 2 and 10 per cent; hookworm - 1, 1, 4 and 5 per cent; and Toxocara- 4, 2, 3 and 2 per cent. There were significant differences in the levels of Giardia and hookworm found between the four different groups of dogs. No significant gender differences were found, and dogs that were positive for Campylobacter in the Visiting group were significantly younger. CLINICAL SIGNIFICANCE: This study provides current information on the infection rates in specific dog populations in the UK. This is relevant to the veterinary health of dogs and the possible risk of zoonotic infection to humans.