Enzyme activity in terrestrial soil in relation to exploration of the Martian surface

Urease activity in soil is persistent for long periods under low water, low temperature, and sterile regimes, and it was suggested that some form of enzyme-protective mechanism exists in soil. Dublin soil was extracted by sonication in water followed by adding a mixture of salts. Urease activity is associated with the organo-mineral complex thus obtained and is resistant to the activities of proteolytic enzymes. Clay free soil organic matter prepared subsequently by filtration also exhibits urease activity which is resistant to proteolysis. Models consisting of enzymes with bentonite and lignin were found to mimic this resistance to proteolysis. A model system is presented which suggests both the origin and location of soil ureases and a reason for their persistence in nature

Prevalence of iron deficiency in 62,685 women of seven race/ethnicity groups: The HEIRS Study.

BackgroundFew cross-sectional studies report iron deficiency (ID) prevalence in women of different race/ethnicity and ages in US or Canada.Materials and methodsWe evaluated screening observations on women who participated between 2001-2003 in a cross-sectional, primary care-based sample of adults ages ≥25 y whose observations were complete: race/ethnicity; age; transferrin saturation; serum ferritin; and HFE p.C282Y and p.H63D alleles. We defined ID using a stringent criterion: combined transferrin saturation <10% and serum ferritin <33.7 pmol/L (<15 μg/L). We compared ID prevalence in women of different race/ethnicity subgrouped by age and determined associations of p.C282Y and p.H63D to ID overall, and to ID in women ages 25-44 y with or without self-reported pregnancy.ResultsThese 62,685 women included 27,079 whites, 17,272 blacks, 8,566 Hispanics, 7,615 Asians, 449 Pacific Islanders, 441 Native Americans, and 1,263 participants of other race/ethnicity. Proportions of women with ID were higher in Hispanics and blacks than whites and Asians. Prevalence of ID was significantly greater in women ages 25-54 y of all race/ethnicity groups than women ages ≥55 y of corresponding race/ethnicity. In women ages ≥55 y, ID prevalence did not differ significantly across race/ethnicity. p.C282Y and p.H63D prevalence did not differ significantly in women with or without ID, regardless of race/ethnicity, age subgroup, or pregnancy.ConclusionsID prevalence was greater in Hispanic and black than white and Asian women ages 25-54 y. p.C282Y and p.H63D prevalence did not differ significantly in women with or without ID, regardless of race/ethnicity, age subgroup, or pregnancy

Potential Biological Control Agents for \u3cem\u3eNassella neesiana\u3c/em\u3e (Poaceae) Invading Australian Native Grasslands

The introduction and proliferation of exotic stipoid grasses over the past 100 years seriously threatens agricultural productivity and the integrity of Australia\u27s indigenous flora and fauna, particularly its grasslands (McLaren et al., 1998). The full effect on biodiversity by the spread of these grasses is unknown but likely to be major (Hocking, 1998). Conventional control techniques have not stopped the invasion adequately, so it is a priority to find control options to achieve an effective management strategy. A biological control project against Nassella trichotoma and N. neesiana was initiated in 1999 in Argentina. We report on the most recent findings on two pathogens, Puccinia nassellae and Uromyces cf pencanus, selected on the basis of previous results (Anderson et al., 2004), as potential biological control agents against N. neesiana, a South American species that can dominate both pasture and native grasslands in Australia

Power in the Multinational Corporation in Industry Equilibrium

Recent theories of the multinational corporation introduce the property rights model of the firm and examine whether to integrate our outsource firm activities locally or to a foreign country. This paper focus instead on the internal organization of the multinational corporation by examining the power allocation between headquarters and subsidiaries. We provide a framework to analyse the interaction between the decision to serve the local market by exporting or FDI, market acces and the optimal mode of organization of the multinational corporation. We find that subsidiary managers are given most autonomy in their decision how to run the firm at intermediate levels of local competition. We then provide comparative statics for changes in fixed FDI entry costs and trade costs, information technology, the number of local competitors, and in the size of the local market

Impact of tillage system, preceding crops, and P fertilizer on economic performance of flax production

Non-Peer ReviewedConservation farming is a system approach that considers all factors that affect production. Reduced tillage is one of the methods of conservation farming and is becoming increasingly popular on the prairie. This will impact directly on nutrient availability and on fertilizer and other chemical management decisions. Phosphorus (P) supply, and its availability in early stages of plant growth, is critical to the determination of optimum crop yield. Producers frequently avoid P application in flax and increase the P supply in the preceding crops since flax is very sensitive to seed-placed applications of monoammonium phosphate. Along with supplying residual P, a preceding crop such as wheat and canola may also have different impacts on yield and performance of flax depending upon its association with mycorrhizae. Since flax is a highly mycorrhizal crop, it is possible that mycorrhizal associations could be responsible for part of the positive response that flax shows in zero-till systems and the limited P response observed in recent studies. If so then P fertility requirements in flax could be greatly affected by the tillage system and by whether the preceding crop was mycorrhizal or not. Phosphorus fertilization could possibly be reduced or eliminated in flax grown in zero-till following a mycorrhizal crop and optimized in flax grown under conventional tillage management. By more clearly defining the P requirements of flax, canola and wheat grown under different management systems, it is possible to reduce inputs while maintaining or improving crop yield and quality. While many research studies have evaluated the economic impact of tillage systems on N fertility requirements, there has been very limited information available on the economic impact of tillage management and P phytoavailability or on the impact of the tillage system and past phosphorus fertilizer management on phosphorus response of crops. The objective of this study is to evaluate the economic impact of flax on tillage system, P fertilizer application, preceding crop, and level of P fertilizer applied in preceding crop

Effectiveness and reach of a directed-population approach to improving dental health and reducing inequalities: a cross sectional study

Background Childsmile School adopts a directed-population approach to target fluoride varnish applications to 20% of the primary one (P1) population in priority schools selected on the basis of the proportion of enrolled children considered to be at increased-risk of developing dental caries. The study sought to compare the effectiveness of four different methods for identifying individuals most in need when a directed-population approach is taken. <p></p> Methods The 2008 Basic National Dental Inspection Programme (BNDIP) cross-sectional P1 Scottish epidemiological survey dataset was used to model four methods and test three definitions of increased-risk. Effectiveness was determined by the positive predictive value (PPV) and explored in relation to 1-sensitivity and 1-specificity. <p></p> Results Complete data was available on 43470 children (87% of the survey). At the Scotland level, at least half (50%) of the children targeted were at increased-risk irrespective of the method used to target or the definition of increased-risk. There was no one method across all definitions of <i>increased-risk</i> that maximised PPV. Instead, PPV was highest when the targeting method complimented the definition of <i>increased-risk</i>. There was a higher percentage of children at <i>increased-risk</i> who were not targeted (1-sensitivity) when caries experience (rather than deprivation) was used to define <i>increased-risk</i>, irrespective of the method used for targeting. Over all three definitions of <i>increased-risk</i>, there was no one method that minimised (1-sensitivity) although this was lowest when the method and definition of <i>increased-risk</i> were complimentary. The false positive rate (1-specificity) for all methods and all definitions of <i>increased-risk</i> was consistently low (<20%), again being lowest when the method and definition of <i>increased-risk</i> were complimentary. <p></p> Conclusion Developing a method to reach all (or even the vast majority) of individuals at <i>increased-risk</i> defined by either caries experience or deprivation is difficult using a directed-population approach at a group level. There is a need for a wider debate between politicians and public health experts to decide how best to reach those most at need of intervention to improve health and reduce inequalities. <p></p&gt

Ergot: A New Disease Threat to Sorghum in the Americas and Australia

Sorghum, Sorghum bicolor (L.) Moench, is the world’s fifth most important cereal crop, cultivated on about 45 million hectares for food, feed, beverage, and fodder. The most significant technological change since the 1960s has been the development and use of F1 hybrid seed (14), which has lead to a dramatic improvement in the crop’s productivity. Sorghum cultivation in intensive, commercialized systems where yields average 3 to 5 t ha-1 relies almost totally on hybrid seed. In contrast, yields vary widely and average less than 1 t ha-1 in low-input production systems