Placer mining in Alaska II

During July, August and September, 1979, a team from the Mineral Industry Research Laboratory visited a number of placer mining districts that could be reached by automobile, hence at a reasonable cost for transportation. These districts yielded varying amounts of information that will be of value to the industry. The district visited were: 1. Fairbanks, 2. Circle (Birch Creak), 3. Livengood (Tolovana), 4. Manley Hot Springs, 5. Fortymile, 6. Klondike, 7. Kantishna, 8. Yentna.University of Alaska Mining and Mineral Resources Research Institute.Placer mining in Alaska II -- Selected references -- List of figures

Iron Acquisition Mechanisms and Their Role in the Virulence of Burkholderia Species

Burkholderia is a genus within the β-Proteobacteriaceae that contains at least 90 validly named species which can be found in a diverse range of environments. A number of pathogenic species occur within the genus. These include Burkholderia cenocepacia and Burkholderia multivorans, opportunistic pathogens that can infect the lungs of patients with cystic fibrosis, and are members of the Burkholderia cepacia complex (Bcc). Burkholderia pseudomallei is also an opportunistic pathogen, but in contrast to Bcc species it causes the tropical human disease melioidosis, while its close relative Burkholderia mallei is the causative agent of glanders in horses. For these pathogens to survive within a host and cause disease they must be able to acquire iron. This chemical element is essential for nearly all living organisms due to its important role in many enzymes and metabolic processes. In the mammalian host, the amount of accessible free iron is negligible due to the low solubility of the metal ion in its higher oxidation state and the tight binding of this element by host proteins such as ferritin and lactoferrin. As with other pathogenic bacteria, Burkholderia species have evolved an array of iron acquisition mechanisms with which to capture iron from the host environment. These mechanisms include the production and utilization of siderophores and the possession of a haem uptake system. Here, we summarize the known mechanisms of iron acquisition in pathogenic Burkholderia species and discuss the evidence for their importance in the context of virulence and the establishment of infection in the host. We have also carried out an extensive bioinformatic analysis to identify which siderophores are produced by each Burkholderia species that is pathogenic to humans

Evaluating a Prototype Approach to Validating a DDS-based System Architecture for Automated Manufacturing Environments

Data Distribution Services (DDS) are emerging as communication systems in manufacturing environments. One of the key features of a DDS based system is the ability to regain performance levels after the introduction or removal of a DDS participant. In implementing a DDS participant to an existing system, message transport speed and message latency is often sacrificed due to protection problems in OEM software. Validity and suitability for integration of OpenDDS specifically, a manufacturing system is evaluated by defining two implementation scenarios; a flexible approach with a dedicated DDS participant application, and a high speed approach integrating the OpenDDS API directly in the target application. The system is validated by monitoring performance, efficiency and robustness in use and implementation. This result is part of a system architecture, developed for project Smart Industrial Robotics (SInBot), that focuses on maximizing the efficient use of mobile industrial robots during medium sized production runs. This modular system architecture is based on distributed intelligence and decentralized control to enable online reconfiguration of industrial robots in manufacturing facilities

Downregulation of the Escherichia coli guaB promoter by upstream-bound cyclic AMP receptor protein

The Escherichia coli guaB promoter (P-guaB) is responsible for directing transcription of the guaB and guaA genes, which specify the biosynthesis of the nucleotide GMP. P-guaB is subject to growth rate-dependent control (GRDC) and possesses an UP element that is required for this regulation. In addition, PguaB contains a discriminator, three binding sites for the nucleoid-associated protein FIS, and putative binding sites for the regulatory proteins DnaA, PurR, and cyclic AMP receptor protein (CRP). Here we show that the CRP-cyclic AMP (cAMP) complex binds to a site located over 100 bp upstream of the guaB transcription start site, where it serves to downregulate P-guaB. The CRP-mediated repression of P-guaB activity increases in media that support lower growth rates. Inactivation of the crp or cyaA gene or ablation/translocation of the CRP site relieves repression by CRP and results in a loss of GRDC of P-guaB. Thus, GRDC of P-guaB involves a progressive increase in CRP-mediated repression of the promoter as the growth rate decreases. Our results also suggest that the CRP-cAMP complex does not direct GRDC at P-guaB and that at least one other regulatory factor is required for conferring GRDC on this promoter. However, PurR and DnaA are not required for this regulatory mechanism

MEASURING PROBABILITIES IN ATTRACTION VISITATION

Many rural towns and villages fail to achieve their tourism development goals because the pulling power of their attractions is not strong enough. An appropriate combination of minor attractions may be an effective means of increasing the pulling power of these destinations. This study demonstrates a method for predicting the probability of a visit to other attractions based on the visitation of one attraction. Along with other analyses, a series of 11 bivariate logistic regression analyses predicts the probability of tourists visiting the 10 other attractions if they visited a specific attraction. For example, the results indicate that a visit to Sunset Crater may be nearly 19 times more likely when Wupatki National Monument is visited. The study demonstrates that separating natural and cultural attractions, while valid for solving many research problems, is of little value in understanding the behavior of general sightseeing visitors. The results of the research method may be useful for creating a strong image for the destination, cross-marketing attractions, developing packages that sell local lodging and food service, for advertising and for developing tours

Smallholder Income and Land Distribution in Africa: Implications for Poverty Reduction Strategies

This paper provides a micro-level foundation for discussions of income and asset allocation within the smallholder sector in Eastern and Southern Africa, and explores the implications of these findings for rural growth and poverty alleviation strategies in the region. Results are drawn from nationally-representative household surveys in five countries between 1990 and 2000: Ethiopia, Kenya, Rwanda, Mozambique, and Zambia. The paper addresses five major points: (1) why geographically-based poverty reduction or targeting strategies-e.g., focusing on marginal areas-is likely to miss a significant share of the poor in any particular country regardless of targeting efficiency in these areas; (2) why current enthusiasm for community-driven development approaches will require serious attention to how resources are allocated at local levels; (3) why sustained income growth for the poorest strata of the rural population will depend on agricultural growth in most countries, even though the poor generally lack the land and other productive resources to respond directly or immediately to policies and investments to stimulate agricultural growth; (4) why agricultural productivity growth, while most easily generating gains for better-off smallholder farmers, is likely to offer the best potential for pulling the poorest and land-constrained households out of poverty; and (5) why meaningful poverty alleviation strategies in many countries will require fundamental changes to make land more accessible to smallholder farmers. This could be accomplished through various processes, including improvement in land rental markets or perhaps land redistribution. We briefly elaborate on each of these findings.Food Security and Poverty, Land Economics/Use,

Smallholder Income and Land Distribution in Africa: Implications for Poverty Reduction Strategies

Farm Management, Food Security and Poverty, Downloads July 2008-July 2009: 15,

Nonlinear force-free magnetic field extrapolations: comparison of the Grad-Rubin and Wheatland-Sturrock-Roumeliotis algorithm

We compare the performance of two alternative algorithms which aim to construct a force-free magnetic field given suitable boundary conditions. For this comparison, we have implemented both algorithms on the same finite element grid which uses Whitney forms to describe the fields within the grid cells. The additional use of conjugate gradient and multigrid iterations result in quite effective codes. The Grad-Rubin and Wheatland-Sturrock-Roumeliotis algorithms both perform well for the reconstruction of a known analytic force-free field. For more arbitrary boundary conditions the Wheatland-Sturrock-Roumeliotis approach has some difficulties because it requires overdetermined boundary information which may include inconsistencies. The Grad-Rubin code on the other hand loses convergence for strong current densities. For the example we have investigated, however, the maximum possible current density seems to be not far from the limit beyond which a force free field cannot exist anymore for a given normal magnetic field intensity on the boundary.Comment: 21 pages, 13 figure