Mortality and Movement of Spotted Seatrout at Its Northern Latitudinal Limits

Ellis, Timothy Alan North Carolina State University 2014 해외박사(DDOD)

Spotted seatrout (Cynoscion nebulosus) is one of the most economically important sportfish in the U.S. South Atlantic and Gulf of Mexico. The species is uncommon north of Chesapeake Bay but supports large recreational and commercial fisheries in North Carolina and Virginia. However, despite its importance, relatively little is known about spotted seatrout mortality and movement at the species' northern latitudinal limits, including winterkill and the appropriate spatial scale for management. Data from the first comprehensive tag-return study (i.e., high-reward and double tagging) of spotted seatrout in North Carolina were used to estimate bimonthly rates of fishing mortality (F) and natural mortality (M). From September 2008 to October 2012, 6,582 spotted seatrout were tagged and 557 (8.5%) tags were recovered and reported by fishers through August 2014. Estimates of bimonthly F and M varied seasonally and ranged from 0.024-0.139 and 0.062-2.527, respectively. Contrary to findings from North Carolina's recent age-based stock assessment, annual mortality from natural causes was always identified to be much higher than mortality from fishing. In a concurrent telemetry study, spotted seatrout in two North Carolina estuaries were tagged with acoustic transmitters and monitored during three consecutive winters of varying severity. Fates of telemetered fish were inferred from daily movements and used in a multistate capture-recapture model to estimate weekly F, M, and emigration rate. Again, fishing mortality was found to be low relative to natural mortality during most weeks with few inferred harvests of telemetered fish (weekly estimates of F ranged from 0.012-0.078) and more natural deaths (weekly M ranged from 0.012-0.300); most natural deaths occurred when water temperature was below 5 °C. Field estimates of M were supported by the results of two laboratory experiments on the cold tolerance of spotted seatrout, as affected by rapid and prolonged exposure to low-temperature extremes (3, 5, or 7 °C) across upper- (10 ‰) and lower-estuarine (30 ‰) salinities. These empirical estimates of cold tolerance were used to develop temperature-based models for predicting winter M, which were then applied to 1994 to 2013 water temperature data. Estimates of winter M from the last 20 years that were high matched historical winterkill events. Lastly, tag recovery information was used to describe the large-scale movements of spotted seatrout in North Carolina. Regional differences in movement suggest that most spotted seatrout reside year-round within the major estuarine systems of North Carolina but that fish tagged in the northern Outer Banks region tend to be transient. For reported recaptures of spotted seatrout tagged in North Carolina (n = 499), 49 (9.8%) were from outside of the state's jurisdictional boundaries, primarily Chesapeake Bay. Extensive movements southward during fall months and northward during spring and summer months are likely associated with known overwintering and spawning periods for spotted seatrout. In combination, these studies provide much new information about spotted seatrout ecology, stock boundaries, and the relative importance of fishing and natural morality, which will improve future management of this species throughout its geographic range.

Modeling water flow to drains in flat, poorly drained lands

Salem, Hany El-Sadany North Carolina State University 2000 해외박사(DDOD)

Models that are based on numerical solutions to the two-dimensional Richards equation are considered the most accurate method for modeling water flow towards drains. However, input data sets are difficult to obtain and application of these models to certain combinations of soils and boundary conditions may result in numerical difficulties. In this study the different methods that are used to describe flow towards drains are critically examined with the aim of identifying or developing relatively simple methods of describing the drainage processes. The model SWMS_2D, which is based on finite element solutions to the Richards equation, was used as basis of comparison for evaluating other models that are based on solutions to the Boussinesq equation and models based on successive steady state approximation. Solutions were obtained and the models evaluated for different combinations of soils and drainage system parameters. Numerical solutions to the Richards equation show that flow is two dimensional with the vertical component dominant when water table is close to the soil surface. Flow is mostly horizontal for deeper water table conditions, except for the area near the drain where flow is approximately radial. Solutions to the Boussinesq equation for constant drainable porosity values failed to match those produced by solutions to the two-dimensional Richards equation along the whole solution range. Solutions to the Boussinesq equation that consider a variable drainable porosity and correct for convergence using the equivalent depth method underestimated water table drawdown at the midpoint as well as cumulative drainage. Solutions to the Boussinesq equation with a variable drainable porosity overestimated water table drawdown near the midpoint when the radial flow concept was used as a drain boundary condition. However, this method of solution gave results that were closer to solutions to the Richards equation than the other approximate methods considered. A mass balance method that uses combination of Hooghoudt equation and Kirkham solution to predict drainage rates overestimated water table drawdown at the midpoint during the early stage when water table is standing above the drain at the drain. During the same stage, the mass balance approach underestimates drainage rates. Steady state drainage equations are often used to predict drainage rates in models that simulate transient processes. Several steady state equations for drainage to parallel drains were reviewed and evaluated. Relationships between drainage rate and water table elevation at the midpoint between drains, as predicted by the steady state equations are compared to finite element solutions to the Richards equation for both transient and steady state events. When the water table midway between drains is close to the soil surface, the water table elevation at the drain is higher for the transient condition than for the steady state condition. For such conditions, solutions to the steady state condition underestimates the drainage rate-water table elevation relationship q(m) as compared to solutions to the transient conditions. For deeper water table conditions, water table profiles and drainage rates predicted by solutions for steady state and transient conditions were in close agreement. The q(m) relationship predicted by the Hooghoudt equation was always in excellent agreement with the finite element solutions for steady state conditions. An algorithm for predicting drainage rates in terms of average water table elevation was developed. The algorithm, which combines classical solutions by Kirkham for ponded conditions, the Hooghoudt equation for drawdown conditions and an empirical equation for the transition, was tested for conventional and controlled drainage conditions. The new algorithm can be used to predict drainage rates for water table conditions ranging from drain level to a fully saturated profile with ponded surface. Numerical solutions to the two-dimensional Richards equation (SWMS_2D) was used to describe flow rates, water table draw down and hydraulic head for an experimental site in eastern North Carolina. Measurements showed that the water table frequently rose to the surface following intense rainfall events. High head losses near the drain were evident even when the water table was below the soil surface. Predicted and measured results were compared for several hydrologic events. The measured soil parameters had to be adjusted in order to achieve agreement between measured and simulated results. Measured and simulated cumulative drainage and water table draw down were in good agreement except for the zone near the drain. Effects of a sand envelope material and drain trench backfill, both with hydraulic conductivity greater than the surrounding soil, were studied. Numerical simulations showed that high conductivity zones near the drain resulted in slight acceleration of drainage and water table draw down near the drain.

Agricultural Commodity Prices

Thompson, Robert Stanley North Carolina State University ProQuest Dissertat 2021 해외박사(DDOD)

The two essays of this dissertation investigate the determinants of agricultural commodity prices, more specifically those for field crops. Risk is a common theme in agriculture, largely due to the nature of agriculture itself. Farmers make large investments throughout the growing season without knowing with certainty the prices for which they will sell their crop, the size of which is also subject to uncertainty. Those with obligations to purchase these agricultural commodities also face these risks. It is important to develop forecasts of the range of prices and quantities buyers and sellers can expect to receive in the future and the probability those prices and quantities are realized. An investigation into the underlying structure of these markets facilitates the development of these forecasts in a manner consistent with basic economics. Chapter one and two are different applications of the same general approach to developing forecasts. Development of forecasting methods begin with simple theoretical models of the market of interest. Simple theoretical frameworks give the forecaster general direction that can be refined further to add certain market nuances conditional on the amount of information available for model estimation.The goal of chapter one is to accurately characterize planting time forecasts of the joint distribution of price and yield at harvest. It is common practice to derive this joint distribution with a disjoint set of methods that are almost entirely data driven. I use a system of supply and demand to show potential problems that arise with these status quo methods and propose solutions to those problems. The result is the derivation of the joint distribution of price and yield that is consistent with a given market structure. I repeat this exercise with several small changes to the system of supply and demand – each of which comes with its own set of limiting assumptions.Chapter two is an investigation into the primary determinants of corn prices in North Carolina. North Carolina is a corn deficit state. The large amount of feed required to feed the hogs, broilers, and turkeys in North Carolina exceeds the amount produced here, so a large amount must be imported from outside sources. Reliable forecasts of corn prices are useful for informing marketing decisions for buyers and sellers of corn in North Carolina. There is a large literature about forecasting local corn prices. However, much of that research focuses on regions that are not similar to the market in North Carolina and it is uncertain whether results found elsewhere are applicable to the grain deficit state of North Carolina. I first investigate the underlying structure of the market in North Carolina. Then, I test some conventional methods for forecasting accuracy and compare the results to novel methods developed based on the specific market structure in North Carolina.

Methods for Monitoring and Assessing Sturgeon Populations Using Technology

Flowers, Henry Jared North Carolina State University 2015 해외박사(DDOD)

Sturgeons (Acipenseridae) are one of the most threatened taxa worldwide, including populations of Atlantic Sturgeon Acipenser oxyrinchus oxyrinchus. This subspecies is found in rivers and marine areas of the Atlantic Coast of the United States. The National Oceanic and Atmospheric Administration listed Atlantic Sturgeon under the Endangered Species Act in 2012. The listing delineated five Distinct Population Segments (DPS), one classified as threatened (Gulf of Maine) and five as endangered (New York Bight, Chesapeake Bay, Carolina, and South Atlantic). Populations are significantly reduced from historic levels by a combination of intense fishing and habitat loss. Successful restoration of Atlantic Sturgeon depends on a solid foundation of biological data. Traditional fisheries sampling approaches are often limited for federally-listed species such as Atlantic Sturgeon. One alternative is to develop less-intrusive methods using new technologies. Side-scan sonar is an emerging fisheries technology with advantages over traditional sampling techniques, including the ability to efficiently sample large areas and survey fish without physically handling them -- important for species of conservation concern. Acoustic telemetry is another area of rapid technological advances, including smaller, longer-lived tags and new designs for submersible receivers. Online databases facilitate data-sharing between researchers operating autonomous receiver arrays, enabling telemetry studies to incorporate expansive spatial areas. The first objective for this study was to develop methodology using side-scan sonar to survey and assess Atlantic Sturgeon populations. This was accomplished by surveying six North and South Carolina rivers, using a combination of side-scan sonar, telemetry, and video cameras (to sample jumping sturgeon). We surveyed lower reaches of each river, near the saltwater/freshwater interface, on three occasions (generally successive days) and used occupancy modeling to analyze these data. We were able to detect sturgeon in five of six rivers, with estimated gear-specific detection probabilities ranging from 0.2-0.5 and riverspecific occupancy estimates (per 2-km river segment) ranging from 0.0-0.8. Next we used count data from the same side-scan sonar surveys to estimate abundances of sturgeon >1 m in length in conjunction with N-mixture and distance models. Estimated abundances in the Carolina DPS were 2,031 (95% confidence interval: 1,075- 3,858) and 1,912 (1,016-3,616) using N-mixture and distance models, respectively. The Pee Dee River, South Carolina had the highest overall abundance of any river at 1,944 (1,036- 3,646) and 1,823 (976-3,406) using count and distance models, respectively. These estimates do not account for sturgeon occurring in unsurveyed riverine reaches or marine waters. Comparing the two models, the N-mixture model produced similar estimates using less data than the distance model with only a slight reduction of estimated precision. The third objective was to use telemetry to describe long-term movements of Atlantic Sturgeon from the Roanoke River, North Carolina. Six adult Atlantic Sturgeon (presumably males) were implanted with acoustic telemetry tags from 2010-2012. Sturgeon were monitored through a network of passive receivers in North Carolina and eight additional states. A multi-state model was used to estimate movement probabilities among riverine, estuarine, and marine areas. From September 2010 to June 2014, five of six Atlantic Sturgeon were detected in marine portions of three different DPSs. Seasonally, sturgeon were observed to either spend the entire year in marine waters or winter-spring in marine waters, summer in Albemarle Sound and fall in the Roanoke River for spawning. The multistate model suggests seasonally variable movement probabilities. Estimated annual mortality was relatively low (0.03) and detection probability high (>0.50) in most study regions. Sturgeon were observed to spawn in consecutive years or with a year in between spawning events. The complexity of Atlantic Sturgeon movements and the mixing of populations in marine waters add to the potential difficulty in managing the recovery of this species.

Evaluation of Herbal Oils in Various Preparations for Treating Mastitis in Dairy Cattle

Mullen, Keena Ann Elizabeth North Carolina State University 2013 해외박사(DDOD)

The organic dairy industry is growing rapidly in the United States and with its growth is an increasing need for organic treatments for mastitis. Mastitis, or udder inflammation, is often caused by bacterial infection and is conventionally treated with antibiotics. Antibiotics are also used at the end of lactation, known as dry cow therapy, to eliminate existing intramammary infections and prevent new infections from occurring before the next lactation. Organic dairies in the United States are prohibited from using antibiotics in their cattle and thus use alternatives for mitigating mastitis. Mastitis can be measured through culturing milk of cows or measuring the somatic cell count of the milk, which is an indicator of the level of inflammation present and is often transformed into a linear score (SCS). No research has been performed comparing organic and conventional dairies in the southeast where heat and humidity make quality milk production challenging. The goals of the research contained in this dissertation were to compare milk quality on organic and conventional dairies in the southeastern United States and to evaluate two herbal alternatives to antibiotics for use as dry cow therapy. In the first experiment, organic and conventional dairies in North Carolina were compared during the warm months. Seven organically and 7 conventionally managed dairy herds in North Carolina were surveyed in 2010 to record differences in milking procedures, mastitis detection and treatment, and to determine the prevalence of mastitis-causing organisms and milk quality for each management type. Overall infection rate, SCS, and cowlevel prevalence of several mastitis-causing pathogens were not different between organic and conventional dairies surveyed. Because of the similar prevalence of mastitis-causing organisms in organic and conventional dairies in North Carolina, further studies were planned to evaluate alternatives to antibiotics for mastitis mitigation. The second experiment evaluated two commercially available alternatives to antibiotics as dry cow therapy on organic and conventional dairies. Phyto-Mast RTM and Cinnatube(TM) are two intramammary products composed primarily of plant-based oils. In a study comparing Phyto-Mast, Cinnatube, Phyto-Mast and Cinnatube, no treatment, and conventional antibiotic and teat sealant dry cow therapy, the herbal products had no negative effects on milk production or SCS and similar cure and new infection rates to the cows receiving conventional dry cow therapy and the untreated cows. However, the cure rate was difficult to assess and compare because of a low initial infection rate. The potential of Phyto-Mast to cure infections was investigated in the third experiment by testing the antibacterial activity of each of its plant-derived oil ingredients, alone and in combination, in vitro against 3 mastitis-causing pathogens in milk. Only essential oil of Thymus vulgaris (thyme) had a consistently significant antibacterial effect. The fourth experiment examined Phyto-Mast again as a dry cow therapy, this time compared with an internal teat sealant, the combination of Phyto-Mast and internal teat sealant, and no dry cow therapy to determine if an internal teat sealant had any effect on the efficacy of Phyto-Mast. Though the SCS and cure rates of cows receiving either Phyto-Mast, teat sealant, a combination of the two, or no treatment were not different among treatments, the combination of Phyto-Mast and teat sealant had significantly fewer new infections than no treatment. Taken altogether, there is a need for alternatives to antibiotics for organic dairy producers throughout the United States. The herbal treatments tested here did not negatively affect milk production or SCS, and were not inferior to conventional dry cow therapy for preventing new infections from occurring during the dry period. Thyme oil, an ingredient of one of the herbal treatments, has significant antibacterial activity when cultured in milk.

A vision of an open door: The establishment and expansion of the North Carolina community college system

Wescott, Joseph Warren, II North Carolina State University 2005 해외박사(DDOD)

After World War II, university extension centers and public junior colleges preceded the establishment of noncomprehensive community colleges and industrial education centers in 1957. In the establishment of these institutions and the passage of enabling legislation and funding for the industrial education centers in that year is the earliest beginning of the community college system in North Carolina. The decision to build and maintain these centers grew from the great need for education beyond the high school, a need that was not being met by North Carolina's public and private colleges and the desire to provide the state with a well-trained workforce to support the new industries being attracted to the state. Throughout their development and operation, the industrial education centers would be at the center of a controversy over how best to accomplish these goals. Yet their success in opening doors of opportunity to the state's disadvantaged adults and vocationally inclined high school students laid a foundation for the development of a system of comprehensive community colleges in 1963. With the election of a new governor, Terry Sanford, and the passage of the Omnibus Higher Education Act in 1963, the vision of a comprehensive community college system became a reality. The growth of the new system was phenomenal, especially in the turbulent era of the Sixties. The number of colleges doubled and the student population increased over 400 percent from 1963 until 1970. By 1970, the final year in our study, the value of the community college system in providing greater access to higher education for all residents of North Carolina was well established and recognized by the state's leaders and citizens alike.

An investigation of the milled wood lignin isolation procedure by solution- and solid-state NMR spectroscopy

Holtman, Kevin M North Carolina State University 2003 해외박사(DDOD)

Milled wood lignin (MWL) is a fraction of the total lignin in wood but is considered the isolated lignin most representative of lignin in its native state. It is useful for lignin studies because it is isolated relatively free of carbohydrates, however structural changes occur during its isolation. This study presents attempts to evaluate the whole lignin structure with the goal of analysis its structure in intact wood. Solution-state and solid-state NMR experiments and degradative techniques were performed on soluble and insoluble lignins to make an estimation of the interunit linkages. MWL and cellulolytic enzyme lignin (CEL) exhibit only minor structural differences. MWL is lower in beta-aryl ether content, has a higher degree of condensation, and a slightly higher amount of oxidized end group moieties. MWL may derive from the middle lamella to a larger extent than CEL. MWL and lignins isolated from milled wood and REL (Residual Enzyme Lignin) were dissolved using dimethyl sulfoxide (DMSO)/N-methylimidazole (NMI) for NMR analysis. HMQC showed that these lignins are similar from the standpoint of structural moieties present. Quantitative 13C NMR indicates that MWL has a beta-O-4' content lower than that of the wood. Solid-state NMR suggests that MWL had a higher degree of condensation. The milled wood and REL contain a significant portion of high MW material (∼55,000 g/mol) which contributes to their insolubility in aqueous dioxane. Solution-state NMR indicates that prolonged rotary ball milling results in more structural changes than the standard milling technique. There are few differences between samples milled in toluene or under N2 in a vibratory ball mill. Milling under N2 results in a higher MWL yield and the isolated lignin contains higher aliphatic and phenolic hydroxyl contents. The DFRC method is inefficient because it does not completely cleave all beta-O-4' linkages. Inefficiency increases with molecular weight indicating that the cause is either accessibility or molecular mobility in the reductive cleavage step. Thioacidolysis completely degrades the beta-aryl ether linkages in lignin and is therefore preferrable for analysis of these structures.

Heritage tourism: An analysis of perceived authenticity and economic impact of the Scottish Highland Games in North Carolina

Chhabra, Deepak North Carolina State University 2001 해외박사(DDOD)

Short-term events such as festivals are important components of heritage tourism. Heritage tourism provides economic benefits and cultural sustainability to local communities. This dissertation analyzes perceived levels of authenticity and spending by visitors to heritage festivals. The economic impact of visitor expenditures upon the host regions in North Carolina (USA) is also analyzed. Existing and potential visitor target markets are identified. The festivals studied are Scottish Highland Games, and analyses are based on survey data collected from Grandfather Mountain Highland Games and Flora Macdonald Highland Games held in North Carolina. Perceived authenticity is measured as the average authenticity rating of events offered at the Games and statistically related to visitor characteristics. Second, visitor expenditures are compared across age and income groups and regressed on other visitor characteristics, including the visitors' experience at the event. Finally, economic impact of total visitor expenditures is estimated with an input-output model that calculates income, output and value added impacts. The results provide useful insights for Highland Games and local government officials with respect to future promotion. Highland Games in the United States are staged authenticity, but this does not make them inauthentic. There are important differences in perceptions of authenticity among visitors with regard to gender and historical background. Tourist expenditures are positively related to annual household income and distance traveled. When potentially endogenous attributes acquired at the Games (such as enjoyment) are added to the model, they increase the statistical significance of the model. Finally, the Highland Games visitor expenditures have the biggest economic impact on the lodging industry. This is followed by impacts on eating and drinking, admission and registration, gasoline and retail industries. Since the multipliers are small, the games have a rather small percentage impact on their host regions. However, they generate both large direct expenditures as well as indirect and induced effects. The results of this study show that the Highland Games boost heritage tourism in North Carolina by providing events perceived as authentic and economic benefits to the local community.

Increasing the Supply of Donor Milk: The Impact of Lactation-Duration Based Exclusion Criteria and Internet Milk Sharing

Perrin, Maryanne Tigchelaar North Carolina State University 2015 해외박사(DDOD)

Pasteurized human donor milk is an important functional first food for the preterm infant who does not have access to their mother's own milk, significantly improving health outcomes and lowering health care costs. Despite a renaissance in donor milk banking in North America that has resulted in the opening of 5 new milk banks since 2012, the demand for donor milk currently outpaces supply. This dissertation uses quantitative and qualitative methods to research potential solutions for expanding the supply of pasteurized donor milk available through the Human Milk Banking Association of North America (HMBANA). In study 1, the composition of human milk was examined longitudinally during the second year of lactation to evaluate the current guideline that prohibits milk donation beyond one year postpartum. Nineteen mothers provided monthly milk samples (N=131) from eleven months postpartum (the control) until 17 months postpartum. Milk samples were analyzed for macronutrients, minerals, and bioactive proteins. There was no evidence of a change in the lactose, total fat, iron, and potassium content of the milk over the study period. Total protein, lactoferrin, lysozyme, immunoglobulin A (IgA), and sodium increased over time, and there was a gradual decrease in zinc and calcium (P < 0.05). Milk samples beyond one year postpartum were also compared to pooled milk samples (N=33) provided by two HMBANA milk banks. In this analysis, late lactation samples contained significantly more total protein, lactoferrin, lysozyme, and IgA, and significantly less zinc, calcium, and iron than milk bank samples (P < 0.05). There was no evidence of a difference in total fat, lactose, potassium, and sodium. These findings suggest that human milk beyond one year postpartum provides stable or increasing concentrations of macronutrients and bioactive factors, and may require mineral fortification to meet the unique needs of the preterm infant. In study 2, an observational approach was used to describe the nature of online milk sharing communities that facilitate the direct exchange of unpasteurized human milk between milk seekers and donors. The purpose of this study was to quantify the different segments of the human milk market in the United States. Three months of data were extracted from nine public Facebook pages that facilitate the exchange of human milk. The number of participants, interactions and comments were analyzed. We observed 954 individuals participating in milk sharing, with 532 of the participants (55.8%) offering milk and 413 participants (43.3%) seeking milk. The top reasons participants requested milk was "Lactation Problems" (69.4%). Nearly half of the donors were offering 100 ounces or more. This is the minimum donation volume to be eligible to donate to many HMBANA milk banks, suggesting that donors who participate in online milk sharing communities may also be a potential pool of donors for non-profit milk banks. Additionally, the study raises questions about the root of lactation problems that are prompting mothers to seek milk. In study 3, in-depth telephone interviews were conducted with 27 women who had shared milk with a peer, but not with a milk bank. A Grounded Theory approach was used to analyze content and develop a preliminary theoretical model that describes the process of becoming a peer-to-peer milk donor. Our findings suggest that an unexpected surplus of expressed milk prompts donation. Information about donation options comes predominantly from social circles, not from health care providers. Donors are concerned about milk bank costs, convenience of donation, and community impact. Insights from this model can be used to develop strategies to address the public health call for increasing the availability of pasteurized donor milk including developing prenatal promotion and screening programs to increase the number of milk bank donors. Funding Sources: North Carolina State University CALS Dean's Enrichment Grant; American Society of Nutrition's Gerber Foundation Predoctoral Fellowship Award; United States Department of Agriculture Kannapolis Scholars Training Grant; Mothers' Milk Bank, San Jose, California; Mothers' Milk Bank, Denver, Colorado; Mothers' Milk Bank Northeast, Newton Upper Falls, Massachusetts.

Optimizing roof maintenance and replacement decisions

Al-Ibrahim, Anwar North Carolina State University 2006 해외박사(DDOD)

The objective of this research is to develop a Decision Support System that helps allocation of available funds to optimize roof maintenance strategies. The Decision Support System analyzes different maintenance alternatives available for each roof element and chooses the alternative that maximizes the benefits due to savings resulting from postponing element replacement. The analysis uses the Life-Cycle Cost to calculate the Reduction in Uniform Annual Cost (RUAC) that is used as the economical decision criterion to select the most economical maintenance alternative for each roof element at different condition states. The analysis utilizes integer linear programming to optimize the selection of maintenance actions for the different elements by maximizing the RUAC under budgetary constraints. Excel and AMPL software are used to implement the analysis. This study uses the roofing systems of 28 buildings on the North Carolina State University campus as a model to develop the Decision Support System. Parameters necessary to develop the model are estimated. The analysis is tested on the available data base.