Academic literature on the topic 'LD5655.V851 1990.H644'

<p>The response of foals to the stress of weaning was examined in terms of a behavioral protocol and the responses of plasma ascorbate, serun1 cortisol, and the serum cortisol response to an ACTH challenge. Behavior scores (1 to 10) as an index of stress were assigned to each foal daily, with high scores indicating less stress and better adjustment. The experimental plan was a 2 X 2 factorial of pre-weaning diet and stall weaning method. Foals were raised on pasture supplemented with hay and a pelleted concentrate (PHC) or pasture supplemented with hay only (PH). Foals were placed in stalls singly or in pairs for weaning. Gender influences were also examined. The foals exhibited characteristic behavioral and physiological responses to the social dislocative stress of weaning. Behavior scores were lower in paired than in single foals (p = .008) and tended to be lower in PH than PHC foals (p = .15). No differences in post-weaning plasma ascorbate concentrations were found among treatments. Responses of serum cortisol to an ACTH challenge were lower in PH than PHC foals (p = .001) and in paired than single foals (p = .058), and lower responses were taken to represent adrenal depletion arising from stress. Behavior scores were positively correlated with the response of serum cortisol to ACTH. Both behavioral data and the serum cortisol response to ACTH indicate that foals were better able to cope with weaning stress when supplemented with concentrate prior to weaning and when weaned singly.<br>Master of Science

This research shows that a model that concurrently determines product, production, and capacity can provide better results than a model that makes these decisions sequentially. Three versions of a life-cycle complete concurrent model and corresponding sequential model that solve product, production, and capacity planning problems are mathematically formulated and compared through an hypothetical example. All versions of the concurrent and sequential models consider three types of work centers and corresponding types of capital budgeting projects. Each version of the concurrent and sequential models considers a specific type of capital budgeting project. These are: (1) projects that may be partially accepted with no upper limit, (2) projects that may be partially accepted with an upper limit of one, and (3) projects restricted to values of zero and one. An hypothetical example spanning twelve fiscal periods that included five products, two product sub-groups, one pre-production/post-support project, three production projects, and one support project was developed to enable comparison of the models. Nine comparisons between each of the three versions of the concurrent and sequential models were conducted resulting in a total of 27 comparisons. Comparisons of the models required the development of five computer programs. Four of these programs provided Mathematical Programming System (MPS) formatted mixed integer linear programs (MIP) that were solved using the LINDO/386 optimization program. The fifth program read output from LINDO/386 and provided the future worth of the sequential model. Results obtained from tests of the concurrent and sequential models were compared based upon future worth, capital budgeting projects funded, products funded, production and inventory quantities, and regular and overtime labor levels. For every combination of product sub-group demand and capital budgeting constraint type, the concurrent model always provided the highest future worth. In addition, while both models funded the same set of products, the concurrent model provided more level labor, production and inventory quantities, and support for products. Following these comparisons, it was concluded that, for any capital budgeting constraint type and product sub-group demand, a concurrent model can provide better planning results than a sequential model.<br>Ph. D.

Interference is a major problem in modern wireless communications systems. No longer are background noise and average power loss the limiting factors in system capacity corruption of the available spectrum by multiple access and nearby interference provides the upper limit to system capacity. If the exponential growth of commercial wireless communications is to continue, systems must effectively deal with the increasingly crowded and corrupted spectrum. <p>Direct Sequence Spread Spectrum modulation (DS-SS) combined with Time Dependent Processing represents a valid approach to meeting the needs of future communications systems. Traditionally, the exploitation of cyclostationarity in digital communications signals has been reserved for the hostile communication environments faced by the military. However, the advent of cost-effective, high-speed DSP chips and associated processing hardware have made Time Dependent Processing a viable commercial technology. <p>This thesis presents several forms of the Time Dependent Adaptive Filter (TDAF) which are able to fully exploit the cyclostationarity and high degree of spectral correlation in certain DS-SS signals. It is shown that these optimal TDAFs are able to combat interference from noise, multipath, signals with dissimilar modulation, and signals with similar modulation (multiple access interference). Performance gains are achieved without a knowledge of the specific type of interference and depend solely on the high degree of spectral correlation in DS-SS signals. It is shown that properly designed DS-SS CDMA systems that utilize the TDAF can achieve spectral efficiencies which are within 10% of FDM/TDM systems. <p>Furthermore, these systems reta~n the benefits of wideband modulation and universal frequency reuse traditionally associated with CDMA systems. The net result is a tremendous increase in system user capacity and signal reception quality.<br>Master of Science

The purpose of the study was to determine the salaries and working conditions of agricultural education teachers in the United States. To accomplish this purpose the following objectives were identified: 1. To determine the demographic characteristics of agricultural education teachers. 2. To determine the salaries, salary supplements, and monetary fringe benefits of agricultural education teachers. 3. To determine the nonmonetary benefits of agricultural education teachers. 4. To determine the major instructional and noninstructional responsibilities of agricultural education teachers. 5. To describe the work settings and working conditions in which agricultural education teachers are employed. 6. To determine the work loads of agricultural education teachers. Most agricultural education teachers reported receiving health insurance benefits. However, only a small percentage (14.7%) of respondents reported receiving fully paid health insurance for themselves and their families. In addition, fewer than one-half (41.4%) of the agricultural education teachers reported receiving fully paid major medical insurance, eye care (13.1%), dental care (20.5%), and life insurance (35.3%). Production agriculture and agricultural mechanics remain the predominant subjects taught by agricultural education teachers. However, a majority of agricultural education teachers also reported teaching agriscience. Although only a small percentage (18.8%) of agricultural education teachers advised Young Farmer chapters, most (95.8%) advised FFA chapters. Nearly all (98.4%) agricultural education teachers classified their employment status as full-time. Typically, agricultural education teachers were mployed a mean 11.3 months per year. Most (69.5%) agricultural education teachers were employed in comprehensive high schools with a mean student population of 662.4 students. Agricultural education teachers reported a mean of 6.7 periods in a typical school day and teaching load of 5.2 instructional periods per day. Nearly three-fourths of the respondents reported having one period per day allotted for planning, student visitations, or student conferences.<br>Ed. D.

Polyimides are attractive polymers because of valued intrinsic properties such as high thermal stability and good solvent resistance. At the same time, much effort is put into modifying polyimides to introduce different properties. This thesis describes a study where polyimides were modified with soluble metal compounds in an effort to create microcomposite films in which the location of the composite structure was controlled; namely at the film interfaces. Two different modification techniques were used in this study, in-situ chemical generation and infusion deposition. Results indicate that infusion deposition was successful in producing a gradient microcomposite structure in polyimide films when silver(I)nitrate was the metal dopant. Analysis revealed that formation of the microcomposite structure depends upon the glass transition temperature and precure temperature of the polyimide film being modified.<br>Master of Science

This study attempted to assess the major determinants of interprovincial migration in the People's Republic of China. The findings suggest that the classical gravity and pull-push hypotheses can also find supporting evidence in the People's Republic of China. Basically, the differential socio-economic characteristics and circumstances determined interprovincial population movement, but relatively speaking, the destination factors played more important roles. Among the variables examined in the study, destination investment and agricultural income level had the strongest pull-force on migrants. On the other hand, unemployment of destination was found to have a push-force discouraging migrants. From the contrast between the positive effect of the destination investment and negative one of the destination unemployment, a conclusion was drawn that the interprovincial migration was largely job-related. Moreover, people in the origin with a higher level of industrialization were less likely to migrate. The analysis also found that the higher level of educational attainment at the origin relative to that at the destination, the higher the migration. In addition, in spite of the similar influence of population and distance on male and female migration streams, the socio-economic conditions affected male migration stream to a larger extent than female migration streams.<br>Master of Science

The purpose of this study was to examine whether a relationship exists between parenting styles, adolescent self-esteem, and health risk behaviors. The sample consisted of 343 middle school students from Harrisonburg, Virginia who completed a questionnaire consisting of three major components: parenting styles, self-esteem, and health risk behaviors. The health risk behaviors component contained questions concerning alcohol use, drug use, sexual activity, and eating behaviors. The parenting styles section of the questionnaire classified the participants into one of four types of parenting styles: authoritarian, authoritative, permissive, and neglectful. The Rosenberg Self-Esteem scale divided the participants into one of three levels of self esteem: low, average, and high. The risky behaviors component of the questionnaire classified the participants as being low risk-takers, experimenters, or high risk-takers, with the exception of the eating behaviors component, which classified participants as being either high or low risk takers. In general, no relationship was found between parenting styles, self-esteem, and health risk behaviors.<br>Master of Science