7,934 research outputs found
An Analysis of Prices Paid to Producers of Farm Products in Tennessee, 1866 - 1935
This thesis, dealing with farm prices in Tennessee, has a three-fold purpose. One objective is to present the general trends of farm prices in Tennessee and to show by means of accepted statistical analy-sis the secular trend, seasonal variations, and cyclical (and random) fluctuations of selected farm price series. An analysis of December 1 farm prices of certain crops is made in Chapter III to show the general long-time changes of Tennessee farm prices from 1866 to 1935 while in Chapter IV a detailed time series analysis is made of the monthly farm prices of twenty-two farm products in the State. No effort is made to completely analyze each farm product because that in itself would be a task beyond the scope of this report. In addition certain historical data are offered in an effort to formulate the background of Tennessee farm prices and to show the major changes in the agricultural price structure of Tennessee and the United States during the past one hun-dred and fifty years. A second purpose is to prepare an index of farm prices in Tennessee to facilitate the measurement and analysis of trends in the agricultural industry of the State. This index of prices paid to producers of farm products is not necessarily the final word in an index of Tennessee farm prices. The third broad purpose of this study is to investigate the geo-graphical variations, or regional differences, of the farm price struc-ture of the United States by states for important farm products. Spe-cial consideration is given to the relative farm price position of Ten-nessee with respect to the other states in the nation. Also, attention is given to the major factors which are responsible for these regional price differences
Efficient software implementation of the JBIG compression standard
JBIG is a new binary image compression standard that is designed to handle both text and halftoned documents. It significantly outperforms the CCITT Group 3 and Group 4 standards especially on halftoned documents. The JBIG standard is based on an arithmetic encoder, and it features adaptive probability estimation, adaptive templates, and three different types of prediction. It also allows either sequential or progressive compression of image data. A brief discussion of information theory is given as it applies to image compression. The JBIG algorithm is described, and several techniques are developed to efficiently implement the algorithm in software. The most important techniques include an efficient scheme for building the context that are required, and taking advantage of large all-white or all-black regions of images by designing very efficient loops for processing those areas. Other techniques are also discussed, such as, efficient implementation of deterministic prediction, and an improved method for handling the conditional exchange condition. Timing information is given for the final implementation on several platforms. The JBIG algorithm is compared with the CCITT Group 3 and Group 4 algorithms, and it is tested in noisy environments
Simulation of factors impeding water quality trading market performance
Over the past several decades, market-based approaches to natural resource management have received increased attention as a means to cost-effectively achieve environmental quality goals. Following on what has been hailed a success for reducing air pollution, water quality trading (WQT) has more recently been seen as the next great opportunity for reducing water pollution, especially for nutrient loading. Numerous trading programs have been pilot tested and/or adopted in states throughout the nation, with more than 70 programs now in operation (Breetz et al., 2004). WQT would allow multiple contributors to surface water degradation to determine how best to meet an overarching collective goal related to pollution reduction. WQT takes advantage of differences in pollution abatement costs. In the case of point/nonpoint source trading, such as between wastewater treatment plants (WWTPs) and agricultural producers, it is often the agricultural producers who can achieve a given level of nutrient reduction at less cost through their adoption of various best management practices that reduce sedimentation and nutrient loading to surface waters. Trading would allow WWTPs to purchase âcreditsâ generated by producers who reduced their pollution loading to achieve an equivalent level of reduction as might be required by a regulatory discharge permit at a lower overall cost. While there is substantial evidence that nonpoint sources have lower nutrient reduction costs than point sources, experience with WQT reveals a common theme: little or no trading activity. The success of WQT seems, in part, to depend on the structure of the market created to bring buyers and sellers together to transact exchanges. These outcomes suggest the presence of obstacles to trading that were not recognized in the design of existing programs. To examine the ways that various market imperfections may impact the performance of a WQT market, an agent-based model was constructed which simulated a hypothetical point-nonpoint market. In particular, the market was modeled using a variant of the sequential, bilateral trading algorithm proposed by Atkinson and Tietenberg (1991). Our proposed paper first presents an overview of the simulation modeling technique and then analyzes the effects of two prominent market impediments identified in the WQT literature: information levels and trading ratios. Information levels refer to buyersâ and sellersâ knowledge of each othersâ bid prices. A frictionless WQT market would be one where all of the potential buyers (i.e., point sources) would know all of the sellersâ (i.e., nonpoint sources) offer prices and vice versa. In this full information environment, we can expect that trades would be consummated in the order of their gains. That is, first buyers and sellers to be paired together for trading would be the buyers with the highest offer prices and the sellers with the lowest bid prices. Successive trades will have successively smaller gains until the gap between bid and offer prices reaches zero. This is the textbook Walrasian market and would closely approximate a double auction institution, where all buyers and sellers submit their offers and bids, which are then sorted and matched by a centralized market manager. While the full information scenario serves as a useful benchmark, most existing WQT markets are decentralized in nature, so that limited information causes traders to be matched in a less efficient sequence. A variety of information levels are possible. One side of the market may have more information than the other (limited information) or neither side having any knowledge of the other sideâs bid or offer prices (low information). Each of these scenarios leads to a different sequencing of trades. This paper analyzes the effect of different information levels on market performance. Market performance is measured in terms of cost savings, the number of credits traded, and the average reduction costs under different information scenarios. Trading ratios are a common component of many existing WQT programs. A typical trading ratio of 2:1 requires a nonpoint source to reduce two pounds of expected nutrient loading in order to receive one pound of trading credit. These ratios serve as a âsafety factorâ and are incorporated to account for the uncertainty in the measurement and monitoring of nonpoint source loading. Because nonpoint traders must reduce loading by 2 pounds for every 1 pound emitted by point source traders, there will be a net reduction of 1 pound of expected loading for each trade. So, while inhibiting some trades from ever occurring, trading ratios also have the potential to improve water quality beyond trading with a 1:1 trading ratio. This paper examines these tradeoffs in terms of effects on market performance and then describes procedures that can be used to characterize an optimal trading ratio if one exists. Because WQT programs, by nature, involve complex interactions between economics and the biophysical world, accurately simulating a real-world WQT market requires at minimum a basic understanding of the types of data that watershed models can provide. This paper concludes by briefly discussing data requirements, points of consideration, and integrative techniques used in the simulation of WQT in real-world watersheds.water quality trading, market based, trading ratio, information levels, point source, nonpoint source, simulation, Environmental Economics and Policy, Resource /Energy Economics and Policy,
Choice Experiments to Assess Farmers' Willingness to Participate in a Water Quality Trading Market
Interest has grown in Water Quality Trading (WQT) as a means to achieve water quality goals, with more than 70 such programs now in operation in the United States. Substantial evidence exists that nonpoint sources can reduce nutrient loading at a much lower cost than point sources, implying the existence of gains from trade. Despite the potential gains, however, the most commonly noted feature of existing WQT markets is low trading volume, with many markets resulting in zero trades. This paper evaluates one explanation for the lack of participation from agricultural nonpoint sources. We test for and quantify the intangible costs that may deter farmers from trading even if the monetary benefits from doing so outweigh the observable out-of-pocket costs. We do so by designing and implementing a series of choice experiments to elicit WQT trading behavior of Great Plains crop producers in different situations. Attributes of the choice experiment included market rules and features (e.g., application time and effort, penalties for violations, means of monitoring compliance) that may affect farmers willingness to trade. The choice experiments were conducted with a total of 135 producers at four locations in the state of Kansas between August 2006 and January 2007. A Random Parameters Logit model is appropriate to analyze the resulting data, revealing diversity in the way that the attributes affect farmers choices.Resource /Energy Economics and Policy,
The Mosquito Can Be More Dangerous than the Mortar Round
These words, penned in 1943 by the commander in chief of British forces in Burma during World War II, underline the reality that losses to malaria and other preventable diseases among Allied forces operating in the China-Burma- India theater far exceeded the number of casualties inflicted by enemy action.1 Today, as the global war on terrorism evolves, a similar failure to appreciate noncombat environmental threatsâincluding mosquitoes and other disease- carrying insect vectorsâwill once again degrade combat effectiveness of deployed forces
Impaired tumor growth and angiogenesis in mice heterozygous for Vegfr2 (Flk1)
Abstract VEGF signaling through its tyrosine kinase receptor, VEGFR2 (FLK1), is critical for tumor angiogenesis. Previous studies have identified a critical gene dosage effect of VegfA in embryonic development and vessel homeostasis, neovascularization, and tumor growth, and potent inhibitors of VEGFR2 have been used to treat a variety of cancers. Inhibition of FGFR signaling has also been considered as an antiangiogenic approach to treat a variety of cancers. Inhibition of VEGFR2 with neutralizing antibodies or with pharmacological inhibitors of the VEGFR tyrosine kinase domain has at least short-term efficacy with some cancers; however, also affects vessel homeostasis, leading to adverse complications. We investigate gene dosage effects of Vegfr2, Fgfr1, and Fgfr2 in three independent mouse models of tumorigenesis: two-stage skin chemical carcinogenesis, and sub-cutaneous transplantation of B16F0 melanoma and Lewis Lung Carcinoma (LLC). Mice heterozygous for Vegfr2 display profound defects in supporting tumor growth and angiogenesis. Unexpectedly, additional deletion of endothelial Fgfr1 and Fgfr2 in Vegfr2 heterozygous mice shows similar tumor growth and angiogenesis as the Vegfr2 heterozygous mice. Notably, hematopoietic deletion of two alleles of Vegfr2 had minimal impact on tumor growth, with little effect on angiogenesis, reinforcing the importance of endothelial Vegfr2 heterozygosity. These studies reveal previously unrecognized Vegfr2 gene dosage effects in tumor angiogenesis and a lack of synergy between VEGFR2 and endothelial FGFR1/2 signaling during tumor growth
Tactical and Logistical Compromise in the Management of Combat
In combat operations, sustainability as well as flexibility are paramount concern. Health maintenance and casualty management programs are crucial underpinnings of any such plans and must be thouroughly intrgrated with tactical operations. The structure and operation of medical services is essentially a function of command direction, and the decision for a specific form of supporting activity in any given maneuver is ultimately the responsibility of the operational commander
Introduction to Series and Parallel Circuits
This lesson begins with an introduction on electricity and how it is formed at the molecular level. It then lets learners explore and define a circuit. This introduction is followed by an exploration where learners develop series and parallel circuits using LED lights and motors. Learners then consider what constitutes a series and parallel circuit, open and closed circuit, and a short circuit. The lesson concludes by having learners consider advantages, limitations, and instructional uses of various electronics kits (e.g., Snap Circuits, littleBits, LilyPad, paper circuits, conductive dough) based on their ability to display circuit paths
Local cytokine transcription in naĂŻve and previously infected sheep and lambs following challenge with Teladorsagia circumcincta
<b>Background</b><p></p>
The abomasal helminth Teladorsagia circumcincta is one of the most economically important parasites affecting sheep in temperate regions. Infection is particularly detrimental to lambs, in which it can cause pronounced morbidity and severe production losses. Due to the spreading resistance of this parasite to all classes of anthelmintic drugs, teladorsagiosis is having an increasingly severe impact on the sheep industry with significant implications for sheep welfare. Protective immunity develops slowly, wanes rapidly and does not appear to be as effective in young lambs. To investigate the development of immunity to T. circumcincta in sheep and lambs, we used cytokine transcript profiling to examine differences in the abomasal mucosa and gastric lymph node of naĂŻve and previously infected sheep and lambs following challenge.<p></p>
<b>Results</b><p></p>
The results of these experiments demonstrated that the abomasal mucosa is a major source of cytokines during abomasal helminth infection. A local Th2-type cytokine response was observed in the abomasal mucosa and gastric lymph node of the previously infected sheep and lambs when compared with those of the naĂŻve during the early stages of infection. In contrast, a pro-inflammatory component more was evident in the abomasal mucosa and gastric lymph node of the naĂŻve sheep when compared with those of the previously infected, which was not observed in the lambs.<p></p>
<b>Conclusions</b><p></p>
The greater levels of Th2-type cytokine transcripts in both the abomasum and gastric lymph node of the previously infected compared with naĂŻve sheep and lambs emphasises the importance of these mechanisms in the immune response to T. circumcincta infection. Younger lambs appear to be able to generate similar Th2-type responses in the abomasum suggesting that the increased morbidity and apparent lack of resistance in younger lambs following continuous or repeated exposure to T. circumcincta is unlikely to be due to a lack of appropriate Th2-type cytokine production
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