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.

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.

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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.

The family Soricidae, encompassing shrews, represents a diverse group of small (head-body length 30-178 mm) omnivorous or carnivorous mammals distinguished by unique morphological and physiological traits. Ecologically, shrews are dominant small predators, significantly impacting invertebrate populations. Their foraging strategies are diverse, with species adapted to fossorial, psammophilic, scansorial, semiaquatic, semifossorial, and terrestrial guilds. High metabolic rates necessitate nearly constant food intake, influencing their prey selection and feeding behaviors. Physiologically, shrews exhibit adaptations for thermoregulation, with Soricinae generally having higher mass-specific metabolic rates compared to Crocidurinae, who can enter torpor to conserve energy. These metabolic differences are crucial for their ecological distribution and competition dynamics, particularly in regions where the ranges of subfamilies overlap. Size plays a crucial role in shaping the biology of species, influencing aspects such as behavior, energy balance, thermoregulation, locomotion, and reproductive strategies. This study explores the ecological drivers of size variation with the family Soricidae. Using extensive skull and body measurements from a comprehensive literature review and detailed ecological data, this research examines the relationship between size and ecological factors such as foraging guild, biome, elevation, and venom presence. Larger sizes are observed in semiaquatic guilds and those with venom, while terrestrial species are generally smaller. Biome-related size variations align with metabolic and thermoregulatory adaptations. Additionally, range latitude and elevation significantly correlated with minimum and maximum size measures. These findings underscore the importance of ecological and evolutionary factors in shaping size within Soricidae, providing insights into niche partitioning and species coexistence in insectivorous mammal communities. Competition is a critical driver of speciation and adaptation, significantly shaping ecological communities. This study investigates the predictors of potential competition among shrew species using morphological character displacement as a proxy. I collected skull length (SL) and head-body length (HBL) data for 456 and 457 shrew species, respectively, from an extensive literature review. Using spatial analyses and linear modeling, I examined the relationship between character displacement and factors such as species richness, elevation, and distance from the equator across 1,000 shrew assemblages worldwide. The findings indicate that character displacement, and thus potential competition, increases with the number of shrew species, elevation, and distance from the equator. Conversely, the number of shrew genera negatively correlates with character displacement. Interestingly, the number of non-shrew insectivorous mammal species did not consistently predict competition levels. This study underscores the importance of morphological, ecological, and abiotic factors in shaping competition and adaptation in shrews. The complex interplay of these factors allows for the coexistence of numerous morphologically similar species, highlighting shrews as an ideal taxon for studying morphological diversification and niche differentiation.

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.