1,255 research outputs found
The Oxidative Decarboxylation Of Polyaminocarboxylic Acids - I. A Study Of The Reaction Of Ethylenedinitrilotetraacetic Acid (EDTA) With Cerium (IV) In Acid Solution
The reaction between Ce(IV) and EDTA was followed titrimetrically and spectrophotometrically and was found to occur in stages. Four equivalents of Ce(IV) are reduced per mole of EDTA almost instantaneously at room temperature. With increasing temperature and reaction time an ultimate of about 14 equivalents of Ce (IV) is consumed per mole of EDTA. Carbon dioxide, formaldehyde, and other yet unidentified compounds are the products of oxidation of EDTA. The kinetics of the reaction in aqueous sulfuric acid was studied over the temperature range 11.7°-40°C by a spectrophotometric technique. The effects of the acidity of the medium and of added salts are reported. © 1969 Springer-Verlag
The Entrepreneurial State Goes to Europe: State Economic Policies and Europe 1992
This article investigates state-level export programs in response to the emerging new economic and political regime of Europe 1992. Little related export promotion activity is found, even in states reputed to have the most active entrepreneurial policies. The authors conclude that states have few resources to invest in export promotion and are inappropriate jurisdictions around which to organize such policy, despite the much touted entrepreneurial state
Hierarchical Bayesian Spatial Models for Multispecies Conservation Planning and Monitoring
Biologists who develop and apply habitat models are often familiar with the statistical challenges posed by their data’s spatial structure but are unsure of whether the use of complex spatial models will increase the utility of model results in planning. We compared the relative performance of nonspatial and hierarchical Bayesian spatial models for three vertebrate and invertebrate taxa of conservation concern (Church’s sideband snails [Monadenia churchi], red tree voles [Arborimus longicaudus], and Pacific fishers [Martes pennanti pacifica]) that provide examples of a range of distributional extents and dispersal abilities. We used presence–absence data derived from regional monitoring programs to develop models with both landscape and site-level environmental covariates. We used Markov chain Monte Carlo algorithms and a conditional autoregressive or intrinsic conditional autoregressive model framework to fit spatial models. The fit of Bayesian spatial models was between 35 and 55% better than the fit of nonspatial analogue models. Bayesian spatialmodels outperformed analogousmodels developed with maximum entropy (Maxent) methods. Although the best spatial and nonspatial models included similar environmental variables, spatial models provided estimates of residual spatial effects that suggested how ecological processes might structure distribution patterns. Spatialmodels built from presence–absence data improved fit most for localized endemic species with ranges constrained by poorly known biogeographic factors and for widely distributed species suspected to be strongly affected by unmeasured environmental variables or population processes. By treating spatial effects as a variable of interest rather than a nuisance, hierarchical Bayesian spatial models, especially when they are based on a common broad-scale spatial lattice (here the national Forest Inventory and Analysis grid of 24 km2 hexagons), can increase the relevance of habitat models to multispecies conservation planning
Prediction and prevention of the next pandemic zoonosis.
Most pandemics--eg, HIV/AIDS, severe acute respiratory syndrome, pandemic influenza--originate in animals, are caused by viruses, and are driven to emerge by ecological, behavioural, or socioeconomic changes. Despite their substantial effects on global public health and growing understanding of the process by which they emerge, no pandemic has been predicted before infecting human beings. We review what is known about the pathogens that emerge, the hosts that they originate in, and the factors that drive their emergence. We discuss challenges to their control and new efforts to predict pandemics, target surveillance to the most crucial interfaces, and identify prevention strategies. New mathematical modelling, diagnostic, communications, and informatics technologies can identify and report hitherto unknown microbes in other species, and thus new risk assessment approaches are needed to identify microbes most likely to cause human disease. We lay out a series of research and surveillance opportunities and goals that could help to overcome these challenges and move the global pandemic strategy from response to pre-emption
Fight or Flight: Parental Decisions about Predators at Nests of Northern Bobwhites (Colinus virginianus)
Patterns of nest defense against predators by ground-nesting bird species in the wild are poorly understood, largely because of a historical inability to directly monitor nests. Most nest-defense studies have observed responses elicited from artificial predators or human observers presented to nesting birds, and few have attempted to present these events in the context of predator—prey relationships found in the wild. We hypothesized that predator threat level (e.g., the threat posed to the clutch or to the clutch and the attending adult), parental characteristics, clutch investment, and future reproductive opportunities would influence avian nest-defense decisions. During 1999–2006, we examined predation events (n = 242) from 790 video-monitored Northern Bobwhite (Colinus virginianus) nests. We evaluated parental, predator, daily, and seasonal correlates that potentially contributed to patterns of nest defense by Northern Bobwhites using a model selection approach. The top model showed that nest defense was strongest at nests with larger predators that posed a threat to both adults and the clutch. This model also contained clutch size, but parameter estimates suggest that predator type was the only significant factor determining rates of nest defense. Our results suggest that Northern Bobwhites use the threat posed to the nest and the attending adult by the approaching predator as the primary cue in decisions to engage in nest defense
Early cow's milk introduction is associated with failed personal-social milestones after 1 year of age
Both the American Academy of Pediatrics (AAP) and the Institute of Medicine (IOM) recommend delaying the introduction of cow's milk until after 1 year of age due to its low absorbable iron content. We used a novel computerized decision support system to gather data from multiple general pediatrics offices. We asked families whether their child received cow's milk before 1 year of age, had a low-iron diet, or used low-iron formula. Then, at subsequent visits, we performed a modified developmental assessment using the Denver II. We assessed the effect of early cow's milk or a low-iron diet on the later failure of achieving developmental milestones. We controlled for covariates using logistic regression. Early cow's milk introduction (odds ratio (OR) 1.30, p = 0.012), as well as a low-iron diet or low-iron formula (OR 1.42, p < 0.001), was associated with increased rates of milestone failure. Only personal-social milestones (OR 1.44, p = 0.002) showed a significantly higher rate of milestone failure. Both personal-social (OR 1.42, p < 0.001) and language (OR 1.22, p = 0.009) showed higher rates of failure in children with a low-iron diet.
CONCLUSIONS: There is an association between the introduction of cow's milk before 1 year of age and the rate of delayed developmental milestones after 1 year of age. This adds strength to the recommendations from the AAP and IOM to delay cow's milk introduction until after 1 year of age
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