3,686 research outputs found
Information Content of USDA Rice Reports and Price Reactions of Rice Futures
Rice is a predominant food staple in many regions of the world, and it is important to determine how efficiently the U.S. rice market helps to ensure world food security. This question can be answered by gauging the price discovery performance of the U.S. rice futures market and the economic usefulness of the U.S. government’s supply and demand forecasts. So, to this end, we employ two event study approaches: (1) to examine variability in returns on report-release days as compared to returns on pre- and post-report days, and (2) to regress price reactions on changes in usage and production information. It is found that the USDA provides the rice futures markets with valuable information and rice futures respond to the information in an economically consistent manner
Markets and Supply Chains: An Investigation of the Institutions Influencing the Farm-Supply Chain Interface
Farm-level operations have lasting and amplified impacts that promulgate the entire supply chain, and the farm is increasingly in the forefront of today’s headlines on topics such as social responsibility, environmental sustainability, traceability, and food safety. Despite its significance, however, the farm remains a ‘black box’ and has traditionally operated independently with little information-sharing, trust, or collaboration with buyers downstream. This dissertation begins to unpack this ‘black box’ by employing different methodologies to identify the factors influencing exchange in the farm-supply chain interface. In Essay 1, I examine why the farm continues to be a challenge for ‘traditional’ collaborative approaches to buyer-supplier exchange. I use an interpretive approach to identify the individual and institutional factors influencing farmers’ operations decision-making. Field interviews reveal that farmers approach buyer-supplier exchange differently and tend to rely more heavily on market mechanisms to coordinate activities with buyers and inform their decision-making. In Essay 2, I build on this finding to examine the institutional factors influencing exchange in the spot market, which accounts for a majority of the total value of agricultural commodity production. I use a proprietary data set and time series econometrics to investigate how spot market exchanges between farmers and buyers are influenced by the futures market—an institution serving critical informational and risk management functions in the industry. In line with the predictions of Austrian economics, the findings indicate that farmers and buyers use the information conveyed by the futures market as they negotiate prices in the spot market. In Essay 3, I build on this finding and further explore how the futures market influences spot market exchanges by examining how information asymmetry affects the price adjustment process. I draw on economic theory to develop hypotheses that are tested using a proprietary data set and nonlinear time series econometrics. The findings suggest that buyers exploit their informational advantage by adjusting spot market prices asymmetrically. Taken together, the three essays demonstrate how institutions influence decision-making and exchange in the agricultural supply chain and offer important insights for theory, practice, and public policy
The Selfie of Dorian Gray: Adapting Literature for Modern Media
Picture Perfect Dori Gray is a modern adaptation of The Picture of Dorian Gray set in modern America and starring a female Dorian Gray. The work is set up as a web series that takes place on YouTube in the form of a vlog run by Dori herself. The transmedia world consists of both YouTube content and Twitter content that all contribute to one over-arching story world. Modernizing the narrative, setting, media, and characters highlights which literary themes and motifs of the original novel are still relevant today and which symbols have changed since publication. The greatest effect on the novel is likely a result of the new media format, as this format changes not only the setting, but also the narrator and the perspective from which the audience is given access to the story. The purpose of this project was to take a piece of Victorian literature and bring it into the modern world, making it more accessible to a new generation. The new media format makes it possible for people who otherwise would not have been able to access the original work due to language barriers or other such obstacles to enjoy this narrative
Techniques to evaluate the importance of common cause degradation on reliability and safety of nuclear weapons.
As the nuclear weapon stockpile ages, there is increased concern about common degradation ultimately leading to common cause failure of multiple weapons that could significantly impact reliability or safety. Current acceptable limits for the reliability and safety of a weapon are based on upper limits on the probability of failure of an individual item, assuming that failures among items are independent. We expanded the current acceptable limits to apply to situations with common cause failure. Then, we developed a simple screening process to quickly assess the importance of observed common degradation for both reliability and safety to determine if further action is necessary. The screening process conservatively assumes that common degradation is common cause failure. For a population with between 100 and 5000 items we applied the screening process and conclude the following. In general, for a reliability requirement specified in the Military Characteristics (MCs) for a specific weapon system, common degradation is of concern if more than 100(1-x)% of the weapons are susceptible to common degradation, where x is the required reliability expressed as a fraction. Common degradation is of concern for the safety of a weapon subsystem if more than 0.1% of the population is susceptible to common degradation. Common degradation is of concern for the safety of a weapon component or overall weapon system if two or more components/weapons in the population are susceptible to degradation. Finally, we developed a technique for detailed evaluation of common degradation leading to common cause failure for situations that are determined to be of concern using the screening process. The detailed evaluation requires that best estimates of common cause and independent failure probabilities be produced. Using these techniques, observed common degradation can be evaluated for effects on reliability and safety
Assessing the impact of the Lake Kissimmee restoration on apple snails
Seasonal fluctuations in rainfall occur naturally in Florida, historically producing correspondingly large intra-annual and inter-annual fluctuations in lake water levels. As a result, "normal" lake levels are elusive; the norm is for wide fluctuations, a pattern which earned them the descriptive title, "astatic", or unstable (Brenner et. al. 1990). Lake Kissimmee, in Osceola County, FL, had a mean average water level fluctuation of 1.4 meters, but over several years varied as much as 3.7 meters (Grocki 1975).The substrate and vegetative communities, in part, reflect the pattern of hydrologic fluctuations, their timing, duration, and frequency. Topographic variability in lake systems, coupled with their hydrologic patterns, yield a mosaic of shrubby, emergent and submerged plant habitats in the littoral zone of the lake. Fish and wildlife have adapted accordingly, and successfully forage and reproduce in these highly fluctuating systems. Installation and operation of water control structures over the past 40 to 50 years have dampened the degree of hydrologic fluctuations in many Florida lakes, resulting in long term stabilization oflake levels [Holcomb and Wegener 1971, Wegener et. al. 1974, Fox et. al. 1977, Moyer and Williams 1982, Florida Game and Fresh Water Fish Commission (GFC) 1995]. The mean annual flux on Lake Kissimmee was reduced from 1.4 meters to 0.9 meters (Wegener et al 1973). In addition, increased nutrient inputs to Florida's watersheds from agricultural and urban development have resulted in lake eutrophication (Wegener et. al. 1974, Moyer and Williams 1982). As nutrients increased and water levels stabilized, rooted aquatic macrophytes expanded and organic debris accumulated to form undesirable lake substrates. Fish populations suffer from drops in accumulated to form undesirable lake substrates. Fish populations suffer from drops in dissolved oxygen associated with decaying algae and plant matter, the alteration of plant community composition, and poor habitat quality of the substrate (Wegener and Williams 1974).
To remedy these problems in Florida lakes, the Florida Game and Fresh Water Fish Commission initiated a lake restoration program in 1971 which emphasizes the use of a lake draw down to expose sediments (GFC 95). The objective ofthe program is to reduce undesirable plant species, expand desirable plant communities, and consolidate flocculent organic sediments (Holcomb and Wegener 1971, Wegener et. al. 1974, Fox et.
al. 1977, Cooke 1980, Tarver 1980, GFC 1995). In addition, muck removal operations following lake level draw downs are meant to resolve the problem of extensive build up of organic sediments (GFC 1995, Moyer et. al. 1995). The goal of the draw down and restoration activity is to improve aquatic habitat in support of fisheries and wildlife while
improving lake quality for recreational usage (e.g. sport fishing) (Wegener and Williams 1974, Tarver 1980,. GFC 1995). The Florida Game and Fresh Water Fish Commission (GFC), in cooperation with the South Florida Water Management District (SFWMD), conducted a draw down of
Lake Kissimmee from December 1995- June 1996, dropping lake levels by approximately 1.7 meters. The Lake Kissimmee draw down provided an excellent opportunity to investigate the impact of management techniques on an invertebrate which is a critical component of the central lakes food web, the Florida apple snail (Pomacea paludosa, SAY). Although data on the responses of some invertebrate species 2 to draw downs in central Florida are available (Wegener et. al. 1974, Fox et. al. 1977, Butler et. al. 1992), no published studies document the responses of P. paludosa. The Florida apple snail belongs to the tropical family of aquatic snails, Pilidae, which inhabitant wetland areas in Florida, Central and South America, Africa and India. Most Pilidae habitat typically (under natural hydrologic patterns) experiences a seasonal dry down, and the Florida apple snail is no exception. Pilidae snails utilize both a lung and gill for respiration (Andrews 1965). The dual respiratory system enables these animals to tolerate daily and seasonal dissolved oxygen fluctuations, permits egg-laying above water level (eggs thus avoid hypoxia and predation), and, in some Pilid species, enables adults to maintain aerobic respiration during the dry-season (McClary 1964, Burky et al. 1972, Aldridge 1983). Apple snails are critical components of lake food webs in Florida. They are prey to alligators (Alligator mississippiensis)( Delany and Abercrombie 1986), fish (Lepomis
microlophus)(Chable 1947), turtles (Trionyxferox) (Dalrymple 1977), and ibis (Eudocimus albus)(Kushlan 1974). Apple snails comprise over 75% ofthe diet of the limpkins (Aramus guaraunaXCottam 1942), and nearly 100% ofthe diet of endangered snail kite (Rostramus sociabilis)(Snyder and Snyder 1969). Although the majority of the snail kite population occupies wetland habitats in south Florida throughout the year, they have been found to emigrate from this area when the dry season escalates into a prolonged drought (Beissinger and Takekawa 1983, Bennetts and Kitchens 1997). Researchers have identified the central lakes system as a critical refuge for the snail kite during these droughts (Beissinger and Takekawa 1983, Bennetts and Kitchens 1997). In 3 addition, the kites have been consistently nesting (even in non-drought years) on Lake
Kissimmee and Lake Tohopekaliga since the early 1980's, providing further support (in the form of suitable foraging and nesting habitat) for the endangered kite population
(Beissinger and Takekawa 1983, Bennetts and Kitchens 1997).
The impetus for the Lake Kissimmee draw down is habitat improvement for fisheries and wildlife (GFC 1995). A conservation priority ranking system for Florida wildlife identifies the snail kite and limpkin, largely due to their specialized diet of apple snails, as deserving special attention for monitoring and management (Milsap et. a1.
1990).Moyer et a1. 1991 specifically recommended an evaluation ofthe impact of lake draw downs on apple snails. In this report we present the findings of a three-year study
ofthe immediate and long term impacts ofthe Lake Kissimmee draw down and restoration activity on apple snail populations. The objectives ofthis research are as
follows:
• To study the impacts oflake restoration activity (e.g. draw down, muck removal)
on snail populations in several sites throughout the lake by assessing pre-draw
down and post-draw down snail abundance~
• To study the movement patterns of snails to find out what proportion ofthe
population migrates to deeper water or become stranded in the dry down area as
lake levels recede;
• To study the capacity for snails to survive in dry down conditions (Document has 55 pages
Recent results from the study of West Bohemian uranium miners exposed to radon and its progeny.
A brief description is given of the study of West Bohemian uranium miners, and recent and ongoing efforts to improve the quality of the data are summarized. Three recent analyses of the data from the cohort have led to rather different estimates of the excess relative risk of mortality from lung cancer per working-level month. The reasons for these different estimates are described, and it is concluded that estimates of lung cancer risk are strongly influenced by the quality of the exposure estimates, especially by the omission of some exposures accumulated during employment at other uranium mines, following the closure of most of the shafts at the original two mines. The most recent analysis has shown that, in common with other cohorts of radon-exposed miners, the excess relative risk of lung cancer per working-level month is modified by age and time since exposure. An inverse effect of exposure rate was also demonstrated, but it affected only men at very high concentrations and appears to be related to the time pattern of exposure. In addition, the risk was found to differ between the two main mines, possibly due to the influence of arsenic in the dust of the mines
Control of Globular Protein Thermal Stability in Aqueous Formulations by the Positively Charged Amino Acid Excipients
The positively charged amino acids are commonly used excipients in biopharmaceutical formulations for stabilization of therapeutic proteins, yet the mechanisms for their modulation of protein stability are poorly understood. In this study, both lysine and histidine are shown to affect the thermal stability of myoglobin, bovine serum albumin, and lysozyme through a combination of mechanisms governed by their respective functional side chains and glycine, similar to arginine. This study provides evidence that at low concentrations, lysine and histidine interact with proteins by a combination of (1) direct electrostatic interactions with negatively charged side chains, (2) possible binding to high-affinity hydrophobic binding sites, and (3) glycine-mediated weak interactions with peptide backbone and polar side chains. At high concentrations, lysine and histidine act via (4) glycine-mediated competition for water between the unfolding protein and the excipient and (5) sidechain-mediated interaction with apolar regions exposed during unfolding (histidine). Lysine and histidine are useful for biopharmaceutical formulations as they were less destabilizing of the protein structures tested than arginine at concentrations above 100 mM
An extended multiscale principle of virtual velocities approach for evolving microstructure
AbstractA hierarchical multiscale approach is presented for modeling microstructure evolution in heterogeneous materials. Preservation of momentum across each scale transition is incorporated through the application of the principle of virtual velocities at the fine scale giving rise to the appropriate continuum momentum balance equations at the coarse scale. In addition to satisfying momentum balance and invariance of momentum among scales, invariance of elastic free energy, stored free energy, and dissipation between two scales of observation is regarded as crucial to the physics of each scale transition. The preservation of this energy partitioning scheme is obtained through construction of constitutive relations within the framework of internal state variable theory. Internal state variables that are directly computed from the fine scale response are introduced to augment the state equations and describe the inelastic energy storage and dissipation within the fine scale. By virtue of a second gradient kinematic decomposition, the framework naturally gives rise to couple stresses
Woodland caribou and forestry in Northern Ontario, Canada
Expansion of logging in remote Ontario boreal forest requires mitigation of effects on woodland caribou. Three examples of caribou-forestry interaction are reviewed. In two, caribou were apparently displaced from peripheral portions of their winter range by logging. In the third, caribou disappeared when exposed to: logging in a central third of their winter range; increased deer density, and; a probable increase in predation. In all cases there is no evidence of human harvest. The literature plus experience in Ontario suggest the following mitigative techniques: protection of winter concentration areas, significant calving areas and traditional migration routes from logging; directing timber harvest to forest stands of least value to caribou; restricting disturbance to one large clearcut in a peripheral portion of range rather than dispersing it over a large portion as several small clearcuts; modified site preparation and regeneration, and; restricted road access. Research is required on the effect of forestry on caribou with and without mitigation, and on causes for effects observed
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