757 research outputs found
Analysis of Farmland Rental Markets in South Dakota
Leasing of farmland has existed in one form or another at least since feudal times. It has been extensively used in the United States since the post Civi1 War era. Tenant farmers or sharecroppers were once considered a lower socio-economic class subject to exploitation by powerful landowners. More recently, farmland rental has been considered the first rung on the tenure ladder , used extensively by landless persons attempting to become farm operators. This tenure ladder led eventually to full ownership and operation of farmland. The primary objective of this research effort is to reveal some of the major characteristics of farmland rental agreements and the farmland rental market in South Dakota. Specific objectives are to: 1. Examine the structural characteristics of the farmland rental market in South Dakota, including the characteristics of landlords and tenants. 2. Examine the relationship of characteristics of farmland rental market participants to rental agreement terms. 3. Test for significant differences in lease terms by region and by cropping pattern in South Dakota. 4. Examine the ability of the farmland rental market to respond to sport term changes in uncertainty and financial conditions and the types of adjustments that are occurring. 5. Examine terms of rental agreements: a) for presence of conditions for efficient use of resources, and b) to determine if rental agreements distribute costs and returns approximately as output is shared
American Literatures After 1865
This work was created as part of the University Libraries’ Open Educational Resources Initiative at the University of Missouri–St. Louis.
A web version of this text can be found at https://umsystem.pressbooks.pub/ala1865/.
This book is an anthology of American Literatures After 1865, a new revision of the open educational resource entitled Writing the Nation: A Concise Introduction to American Literature 1865 to Present. It contains works that have been newly introduced to the public domain and provides direct links to reading materials that can be borrowed for free from Archive.org
Preliminary analysis of LDEF instrument A0187-1: Chemistry of Micrometeoroids Experiment
The Chemistry of Micrometeoroids Experiment (CME) exposed approximately 0.8 sq. m of gold on the Long Duration Exposure Facility's (LDEF's) trailing edge (location A03) and approximately 1.1 sq. m of aluminum in the forward-facing A11 location. The most significant results to date relate to the discovery of unmelted pyroxene and olivine fragments associated with natural cosmic dust impacts. The latter are sufficiently large for detailed phase studies, and they serve to demonstrate that recovery of unmelted dust fragments is a realistic prospect for further dust experiments that will employ more advanced collector media. We also discovered that man-made debris impacts occur on the LDEF's trailing edge with substantially higher frequency than expected, suggesting that orbital debris in highly elliptical orbits may have been somewhat underestimated
High quality protein microarray using in situ protein purification
<p>Abstract</p> <p>Background</p> <p>In the postgenomic era, high throughput protein expression and protein microarray technologies have progressed markedly permitting screening of therapeutic reagents and discovery of novel protein functions. Hexa-histidine is one of the most commonly used fusion tags for protein expression due to its small size and convenient purification via immobilized metal ion affinity chromatography (IMAC). This purification process has been adapted to the protein microarray format, but the quality of <it>in situ </it>His-tagged protein purification on slides has not been systematically evaluated. We established methods to determine the level of purification of such proteins on metal chelate-modified slide surfaces. Optimized <it>in situ </it>purification of His-tagged recombinant proteins has the potential to become the new gold standard for cost-effective generation of high-quality and high-density protein microarrays.</p> <p>Results</p> <p>Two slide surfaces were examined, chelated Cu<sup>2+ </sup>slides suspended on a polyethylene glycol (PEG) coating and chelated Ni<sup>2+ </sup>slides immobilized on a support without PEG coating. Using PEG-coated chelated Cu<sup>2+ </sup>slides, consistently higher purities of recombinant proteins were measured. An optimized wash buffer (PBST) composed of 10 mM phosphate buffer, 2.7 mM KCl, 140 mM NaCl and 0.05% Tween 20, pH 7.4, further improved protein purity levels. Using <it>Escherichia coli </it>cell lysates expressing 90 recombinant <it>Streptococcus pneumoniae </it>proteins, 73 proteins were successfully immobilized, and 66 proteins were <it>in situ </it>purified with greater than 90% purity. We identified several antigens among the <it>in situ</it>-purified proteins via assays with anti-<it>S. pneumoniae </it>rabbit antibodies and a human patient antiserum, as a demonstration project of large scale microarray-based immunoproteomics profiling. The methodology is compatible with higher throughput formats of <it>in vivo </it>protein expression, eliminates the need for resin-based purification and circumvents protein solubility and denaturation problems caused by buffer exchange steps and freeze-thaw cycles, which are associated with resin-based purification, intermittent protein storage and deposition on microarrays.</p> <p>Conclusion</p> <p>An optimized platform for <it>in situ </it>protein purification on microarray slides using His-tagged recombinant proteins is a desirable tool for the screening of novel protein functions and protein-protein interactions. In the context of immunoproteomics, such protein microarrays are complimentary to approaches using non-recombinant methods to discover and characterize bacterial antigens.</p
The assessment of usability of electronic shopping: A heuristic evaluation
Today there are thousands of electronic shops accessible via the Web. Some provide user-friendly features whilst others seem not to consider usability factors at all. Yet, it is critical that the electronic shopping interface is user-friendly so as to help users to obtain their desired results. This study applied heuristic evaluation to examine the usability of current electronic shopping. In particular, it focused on four UK-based supermarkets offering electronic services: including ASDA, Iceland, Sainsbury, and Tesco. The evaluation consists of two stages: a free-flow inspection and a task-based inspection. The results indicate that the most significant and common usability problems have been found to lie within the areas of ‘User Control and Freedom’ and ‘Help and Documentation’. The findings of this study are applied to develop a set of usability guidelines to support the future design of effective interfaces for electronic shopping
Willingness to Pay for Genetic Testing for Alzheimer's Disease: A Measure of Personal Utility
Background: The increased availability of genetic tests for common, complex diseases, such as Alzheimer's disease (AD), raises questions about what people are willing to pay for these services. Methods: We studied willingness-to-pay for genetic testing in a study of AD risk assessment that included APOE genotype disclosure among 276 first-degree relatives of persons with AD. Results: Seventy-one percent reported that they would ask for such testing from their doctor if it were covered by health insurance, and 60% would ask for it even if it required self-pay. Forty-one percent were willing to pay more than $100 for testing, and more than half would have been willing to pay for the test out of pocket. Participants who learned that they were APOE -4 positive and those who had higher education were less likely to want testing if covered by insurance, possibly to avoid discrimination. Conclusion: This is the first report to examine willingness to pay for susceptibility genetic testing in a sample of participants who had actually undergone such testing. These findings reveal that some participants find valuable personal utility in genetic risk information even when such information does not have proven clinical utility.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90504/1/gtmb-2E2011-2E0028.pd
Assessing the utility of whole-genome amplified serum DNA for array-based high throughput genotyping
Proteomic analysis of iron acquisition, metabolic and regulatory responses of \u3cem\u3eYersinia pestis\u3c/em\u3e to iron starvation
BACKGROUND: The Gram-negative bacterium Yersinia pestis is the causative agent of the bubonic plague. Efficient iron acquisition systems are critical to the ability of Y. pestis to infect, spread and grow in mammalian hosts, because iron is sequestered and is considered part of the innate host immune defence against invading pathogens. We used a proteomic approach to determine expression changes of iron uptake systems and intracellular consequences of iron deficiency in the Y. pestis strain KIM6+ at two physiologically relevant temperatures (26°C and 37°C).
RESULTS: Differential protein display was performed for three Y. pestis subcellular fractions. Five characterized Y. pestis iron/siderophore acquisition systems (Ybt, Yfe, Yfu, Yiu and Hmu) and a putative iron/chelate outer membrane receptor (Y0850) were increased in abundance in iron-starved cells. The iron-sulfur (Fe-S) cluster assembly system Suf, adapted to oxidative stress and iron starvation in E. coli, was also more abundant, suggesting functional activity of Suf in Y. pestis under iron-limiting conditions. Metabolic and reactive oxygen-deactivating enzymes dependent on Fe-S clusters or other iron cofactors were decreased in abundance in iron-depleted cells. This data was consistent with lower activities of aconitase and catalase in iron-starved vs. iron-rich cells. In contrast, pyruvate oxidase B which metabolizes pyruvate via electron transfer to ubiquinone-8 for direct utilization in the respiratory chain was strongly increased in abundance and activity in iron-depleted cells.
CONCLUSIONS: Many protein abundance differences were indicative of the important regulatory role of the ferric uptake regulator Fur. Iron deficiency seems to result in a coordinated shift from iron-utilizing to iron-independent biochemical pathways in the cytoplasm of Y. pestis. With growth temperature as an additional variable in proteomic comparisons of the Y. pestis fractions (26°C and 37°C), there was little evidence for temperature-specific adaptation processes to iron starvation
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