The purpose of this study is to determine whether the size of class in eighth grade general mathematics affects the achievemnt of pupils in the class.

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The smallest display while indistinguishable from the larger three displays in the 3000 ms condition has significant accuracy diminution in the 700 ms and 300 ms conditions when compared to the three larger displays. Understanding the effects of the visual display size of a task on human performance has long been a goal of research in the United States Military. The present work is a series of three studies which focus on distinguishing which specific aspects of display size each affect performance response capacity. The three sequential studies represented here manipulated viewing conditions and task type. These studies were derived from a code substitution cognitive battery using four display sizes and three viewing conditions. The first viewing condition is controlled distance to the display. The second viewing condition allowed the participants to choose their own viewing distance. Free movement, the second viewing condition, provided the data for the third viewing condition where the participant was held to a constant visual angle and changing distance. In summary the three sequential experiments are free movement to and from the display, controlled distance to the display, and controlled visual angle while changing display distance. The four display sizes were in part selected in association with SME's from UCF and the United States Army (PDA--320x280, Tablet--800x600, Small - LCD 1280x1024, Large LCD--1600x1200). These four displays are representative of the four display sizes widely used by our armed forces. Three workload levels were manipulated by restricting the viewing time to 300ms on target at the shortest interval through 700ms on target, to finally 3000ms on target. The 3000ms represents the standard amount of time used in a code substitution task, while 700ms and 300ms are present as a result of the pilot studies and thus representing higher workloads. Results indicate all displays sizes suffered performance diminution in the 700 ms and 300 ms condition. The three largest displays had indistinguishable performance results.

No / We document rich variation across observed firms’ characteristics, and the accompanying macroeconomic volatility, often related to political turmoil for Ukrainian manufacturing firms. We use a unique annual firm-level data for the period from 2001 to 2009 compiled from the Derzhkomstat. To understand the evolution of distributions we utilize functional principal component analysis while accounting for the effects associated with firms’ region, industry, trade status, and firm turnover. The overall improvements in firm productivity in Ukraine’s manufacturing in 2001–2009 vary substantially by industry, trade status and with firm turnover, while regional effects are less important.

A research report submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the Degree of Master of Science in Engineering. May, 2016 / Particle size and size range are among the characteristics that affect the segregation of particles in a jig hence they affect the separation efficiency. The effects of these variables on segregation of particles are not fully understood. This work aimed at contributing to knowledge in this area. To better understand how particle size and size range influence segregation, tests were conducted in which the effects of the density and shape of the particles on segregation were minimized by using as the feed material spherical glass beads of uniform shape and density. Batch experiments of two components systems of various particle sizes were conducted under the same set of jigging conditions: the jigging frequency and jigging time were respectively maintained at 60 cycles per minute and 999 seconds (16.65 minutes). The effect of these operating conditions on segregation was not investigated. At the end of each test run, the jig bed was split into horizontal slices and the composition of each slice was determined. The experimental results showed that below a particle size ratio of 1.50:1, the driving force for the segregation of particles, i.e. the particle size difference, was small hence a low degree of segregation was obtained. The degree of segregation increased above this ratio. However, above the size ratio of 2.00:1, interstitial trickling occurred. With the smaller particles tested (8, 6 and 4mm) poor segregation was observed when the size ratios were of 1.50:1 or less along with what is believed to have been remixing due to convective currents within the jig chamber. It was found that the particle size range had a more pronounced effect on size segregation than the particle size. From the results, it can be said that above a size ratio of about 1.50:1, size segregation is very pronounced. This suggests that density separations of real ores, where both the density and size of particles vary, would be impaired if the particle size range of the material fed to the jig exceeds this ratio. However, this needs further confirmation by testing multiple component systems.

The purpose of this study is to measure the direct and indirect relationships between socio-economic and demographic variables and ideal and desired family size preferences among male and female high school seniors in Utah in 1974. Furthermore, the analysis will be carried out separately for males and females in order to see if male and female ideal and desired family size preferences are influenced differently by the socio-economic and demographic variables. A model will be developed and tested of the process by which ideal and desired family size preferences are formulated. The model used in the analysis is based upon Westoff and Potvin's "theory of ideal family size formation." Westoff and Potvin's "theory of ideal family size formation" states family size of female's is a result of early socialization. The socialization can be influenced by four categories of processes. The four categories are family size in e nvironment variables, social context variables, consistency and continuity in life experiences, and interaction between beliefs and behavior. The socio-economic and demographic variables selected to test this model were size of family of orientation, place of residence, social class, religion, religiosity, desired age at marriage , ideal age at marriage, the number of circumstances females or males would consider acceptable for the use of birth control, and education difference. The application of Westoff and Potvin 's "theory of ideal family size formation" was a better fit for desired family size of females or males than ideal family size of females or males. Desired family size of females was influenced by religion, religiosity , size of family of orientation, and the number of circumstances females/males find acceptable for the use of birth control. Desired family size of females was also influenced by social class. Ideal family size of females is different from ideal family size of males. Both ideal family size of f emales and males was influenced by religion. Ideal family size of males was al so influenced by religiosity and social class. The given socio-economic and demographic variables explained 39 percent of the variation for female desired family size and 29.5 percent of the variation for male desired family size. The given socio-economic and demographic variables explain 4 percent of the variation for female ideal family size and 17 percent of the variation for male ideal family size.

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In this thesis the positive relationship between firm size and wages is investigated through the application of hierarchy theories. Many different explanations have been proposed for this relationship, but have met only limited success at best. The strongest finding to date is that unobserved ability is a significant factor. The question of interest here is ???why do wages increase as the size firm increases???? Hierarchy theories take a different approach towards the analysis of firms in comparison to the alternate theories which have dominated previous investigations. As a result of their focus on the organisational relationships within a firm???s internal structure, hierarchy theories offer certain insights to the size-wage relationship which to date have been unnoticed. An empirical investigation into the size-wage differential incorporating structural considerations into an augmented wage equation offers strong support for the propositions of hierarchy theories. I find that half of the firm size effect for workers can be explained by controlling for some aspects of management structure, and that span of control has a discontinuous effect on wages. These results are completely consistent with the existing findings on unobserved ability and have the added attraction of providing economic as well as statistical explanatory power.

Particle size distribution (PSD) of gypseous soils is important in the soil science community. When gypsum constitutes a major portion of the soil, its removal prior to PSD analysis distorts the results and may lead to textures that do not relate to conditions in the field. In order to understand the true characterization of the soil and the gypsum particles, the entire soil sample should be analyzed. Four different approaches to the BaCl2 method presented in the literature (Hesse, 1976, Matar and Douleimy, 1978, Viellefon, 1979) were used to evaluate the use of BaCl2 solution to reduce the solubility of gypsum by forming a protective coating of BaSO4 around gypsum particles. Results showed that the BaCl2 method was unsatisfactory, as dispersion of clays was not sufficient to allow particle size analysis using the pipette method. A procedure using a laser diffraction particle size analyzer (LPSA) was also evaluated. As gypsum is insoluble in methanol, methanol was selected as a possible solution, but it caused flocculation of clays and could not be used to analyze samples containing silicate clays. Gypsum saturated water containing Na hexametaphosphate was evaluated as a solution. First, 20 non-gypseous samples were analyzed on a sand-free basis using saturated gypsum water with Na hexametaphosphate. Results were used to establish a relationship comparing LPSA results and pipette results. An equation y = 1.37x + 2.03 was established relating LPSA clay percent by volume (x) to the pipette clay percent by weight (y). The equation had a R2 value of 0.84 and was significant at the 1% level. From this equation a comparison of 21 gypseous samples was made, between clay percentages of the pipette method and the LPSA method. Results indicate that LPSA can be used to give a satisfactory particle size distribution of gypseous soils when coupled with sand analysis by sieving.