The interest in year-round education has grown considerably since 1964, but the associated research and evaluation has not kept pace. The present status of how teachers' attitudes have been affected by changing the school calendar from a traditional nine-month term of operation to year-round operation has been widely debated. Prior information on this topic is almost non-existent. The need for such information has been evident by the increasing number of teacher organizations, school boards, lay persons, and school administrators seeking information from the National Council on Year-Round Education regarding year-round education as it relates to teachers' attitudes. This study was formulated to provide evidence related to: How selected personal and situational variables relate to teachers' attitudes toward year-round education and how can variations in those attitudes be measured. An assessment instrument, the Teacher Attitude Inventory On Year-Round Education, was designed to determine the relationship between teachers’ attitudes on year-round schools and selected personal and situational variables. Principals of participating schools provided faculty lists which made up the total population of the study and also indicated a contact teacher in the school that would receive, distribute, collect, and return the completed inventories to the researcher. Of these lists, 30% or 800 teachers were included in the sample. The teachers were from 103 operational 45-15 year-round schools in the United States. Returns were received from 75.73% of the schools and 69.50% of the teachers who agreed to participate. Data was electronically transferred to cards and analyzed using the following computer programs: (1) BMDO4D, Frequency Count; (2) BMDO2R, Stepwise Regression; and (3) BMDO8M, Factor Analysis. The analyses were performed on the IBM 370/158 computer at Virginia Polytechnic Institute and State University. The assessment instrument designed for this study was found to be unidimensional, measuring a single major attitudinal construct relating to year-round education. Four sub constructs relating to year-round education were determined that reflected teachers' attitudes toward: (1) Calendar/Program, (2) Administration, (3) Student Welfare, and (4) Teacher Welfare. The internal consistency of the instrument was determined to be 0.5565. A significant relationship was found between the following personal and situational variables and teachers’ attitudes toward year-round education: (1) favorability toward year-round schools, (2) morale, (3) fatigue, and (4) quality of the educational program related to the subconstruct on Calendar/Program; (5) providing adequate support staff related to the subconstruct on Administration, and (6) fringe benefits related to the subconstruct on Teacher Welfare. None of the personal and situational variables related to the subconstruct on Student Welfare. The following personal and situational variables were determined not to have any significant relationship to attitudes expressed by teachers toward year-round education: (1) type of school calendar utilized prior to the year-round calendar, (2) number of students enrolled, (3) population density of the school-community setting, (4) sex, (5) age, (6) marital status, (7) total teaching experience, (8) teaching experience in year-round school, (9) teaching level, (10) calendar preference, (11) student-teacher ratio, (12) level of professional attainment, (13) degree of program development participation, (14) professional association membership, (15) options on contract length, (16) work participation option, (17) vacation option, and (18) salary adjustment. / Ed. D.

A constitutive equation for whole human blood was developed using a power law functional form. This power law equation contains two parameters, the consistency index and the non-Newtonian index for the fluid. Viscometric data, utilizing a cone and plate viscometer, were obtained from anticoagulated blood samples of known hematocrit levels and chemical compositions. A multiple regression technique with apparent viscosity as the dependent variable was used to determine the consistency index and the non-Newtonian index. A model including only the shear rate as the independent variable was found to be lacking any substantial degree of significance. When hematocrit was added as an independent variable, the degree of fit increased considerably. Of the chemical variables examined, the least significant, as far as effects on viscosity is concerned, were the plasma lipids. The proteins, fibrinogen and globulin were found to have a much greater effect on viscosity than the protein, albumin. The best constitutive equation involving the chemical composition of blood was found to include the shear rate, the hematocrit level, and a variable which is the sum of fibrinogen and globulin. This model produced a statistically significant increase in the correlation between experimental and theoretical data compared with the best two variable model. / Master of Science

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Determination of some form of modulation detectability threshold for sinusoidal gratings is a prerequisite to use of most measures of image quality for line-scan imaging systems. To develop predictive models for these thresholds, an experiment was conducted to determine the modulation detectability threshold functions for a range of system parameters typical of medium- to high-resolution low-light-level television systems. Specifically, the psychophysical method of adjustments with target grating modulation as the dependent variable was employed in an experiment where, at each of 10 combinations of video line rate and video noise passband, each of 7 subjects received 2 replications at every combination of 10 spatial frequencies, 2 target orientations, and 5 noise amplitudes. Line rates were 525, 945, and 1,225 lines per frame; the spatial frequencies were between 1 and 20 c/deg; and the gratings were oriented vertically (perpendicular to the video raster) and horizontally (parallel to the raster). As the three highest spatial frequencies were not used at the 525 line rate, horizontal orientation, there were 13,160 trials. The target gratings were displayed in a 6.375 in. (16.2 cm) square center portion of a 10 in. by 14 in. (25.4 cm by 35.6 cm) video monitor with both the grating and surround having a mean luminance of 15 fL (14 mL). Viewing distance was 40 in. (101.6 cm). Using a step-wise regression technique to evaluate candidate variables, a model predicting the modulation threshold as a function of the other variables was developed for each grating orientation. In the vertical orientation, a correlation coefficient of .77 was achieved between the experimental data and a three-variable equation consisting of a variable representing the integration of noise power from zero spatial frequency to the grating spatial frequency, the value of the modulation threshold determined by DePalma and Lowry (1962) at the grating spatial frequency, and a variable representing the noise power in the spatial frequency region of the grating. The addition of twenty-two other variables increased the correlation to .82. For the horizontal orientation, a similar correlation of .74 was obtained with a three-variable equation including the variable representing an integration of noise power from zero to the grating spatial frequency, the inverse of the raster spatial frequency, and a shaping variable equal to the square of the grating spatial frequency minus 9 c/deg . The inclusion of twenty-three additional variables yielded a .81 correlation coefficient. The correlation coefficients are between the models and the complete data sets, not means across subjects and replications. These models are useful in the application of the modulation transfer function area and other spatial frequency-based line-scan image quality metrics. / Ph. D.

The chemical substitutions of primary importance in natural titanites are (Al,Fe)³⁺ + (F,OH)^- ⇆ T₁⁴⁺ + O^2- , where total Al + Fe is not greater than 30 mol % and Al is usually predominant. Electron microprobe analyses and bond strength considerations suggest that Al prefers the octahedral site in natural titanites, whereas ubiquitous rare earths substitute for Ca. Ion microprobe mass analysis indicate that Pb, U, and Th are present in all but two specimens examined, both of which are from pegmatites. Trace level concentrations of elements not previously reported in natural titanites including Ru, Pd, Ag, and Te were detected by this technique. The lattice parameters of titanites vary directly with the effective octahedral cation radius. As in zircon, partial metamictization of some titanites causes increases in unit cell dimensions and decreases in density. Under electron bombardment, the characteristic x-ray yields are lower for metamict titanites than for their structurally restored 0 equivalents which were heated at 1100 C for three hours. The formation of out-of-step linear domains parallel to 100 (the octahedral chain direction) is favored by substitutions of Al + Fe for Ti. Pure CaT10SiO₄ is primitive (P2₁/a) with weak, but sharp k + ℓ odd reflections. Increasing Al + Fe substitution increases the frequency of domains and the k + ℓ odd reflections become diffuse, eventually disappearing as the average structure attains space group A2/a. / M.S.

An investigation of the occurrence and distribution of portions of insect communities in selected riffles along the longitudinal gradient of Sinking Creek, Virginia was conducted over a twelve month period. Seasonal changes in total numbers of individuals and species were observed. Temporal changes in community dominance occurred throughout this study. Change in community composition was illustrated by variation in community dominance and in total numbers of individuals and species collected. The observed temporal and spatial distributions of thirty-six species were considered. Temporal distributions illustrate variations in the length of time individual species require to complete the aquatic portion of their life cycle, while differences in the observed longitudinal distribution of particular species indicate population responses to environmental change at points along the stream gradient. The spatial and/or temporal segregation of closely related organisms was indicated by seasonal and/or longitudinal differences in the relative abundance of particular species. Except for one family Hydropsychidae selected closely related species exhibited either spatial separations, temporal separations 1 or a combination of both spatial and temporal separations. Speculations on factors influencing the distributions of selected species are included. Baseline data indicate seasonal and longitudinal fluctuations. of physico-chemical parameters during this study. A discussion of these seasonal and longitudinal fluctuations is included. / M.S.

Although soy protein is considered to be an excellent source of lysine, the effect of extrusion on lysine availability in commercial textured soy protein of the hamburger extender type had not been reported. The purpose of this research was to determine the effect of extruder processing on the lysine availability in textured soy protein. York soy and three brands of textured soy protein were studied, Protein content of defatted, dehulled York soy measured 43%, while the protein content of the three textured products was 51, 54, and 49%, Available lysine was measured using the methods of Kakade and Liener (1969 ). Molar absorptivity of ε -TNP-L-lysine HCl was 1.5 x 10⁴M^-1 cm^-1, a value which compared favorably to values reported in the literature. When soy samples were analyzed, no significant difference between the available lysine content of the samples was observed, although processed products had slightly lower available lysine values than did the unprocessed soybeans. The Kakade and Liener (1969) TNBS procedure provided a quick reproducible measure of lysine availability. The results of this study indicated that lysine availability in textured soy protein was not altered significantly during processing. / M.S.

The feasibility of refining a finite element by dividing only selected elements is examined. A method is developed which selects these elements so as to maximize the strain energy of the refined mesh. Repeated application of the method results in the generation of a series of refined meshes. The method is completely automated and becomes an integral part of a finite element program. The feasibility of the method is demonstrated through the study of several example problems with concentrated loads. Extension of the method for use with meshes subjected to distributed loadings would require the development of additional criteria for selecting the elements to be refined. / M.S.

The highway system was classified into its main elements and the variables affecting each element were identified and shown how they fit into a matrix description of highway accidents. A statistical methodology was provided and applied that can effectively be used in analyzing the system of accident related variables and determining their relationship with highway accidents. Several different regression equations were calculated which use variables from the roadway/environment element of the highway system. These equations were calculated using “dummy” variable techniques as well as the analysis of grouped data, and comments were provided on the use of each technique. The equations were useful in providing information about the roadway/environment to the analyst or decision maker in relationship to highway safety. / M.S.