The problem of this study is to determine the effects of two different social climates, as created by different teaching methods, upon the characteristics of college class groups. The social climates utilized in the present investigation were: (a) a democratic social climate, and (b) an autocratic social climate. The actual meaning of the adjectives used to label these social climates is necessarily somewhat different from the meanings attributed to them in political or economic discussions.

No description available.

Thesis (Ph.D.) -- University of Melbourne, School of Earth Sciences, 2005. / Typescript. Includes bibliographical references (leaves 239-266).

Thesis (M.S.) in Ecology and Environmental Science--University of Maine, 2004. / Includes vita. Includes bibliographical references (leaves 34-38).

No description available.

Crop emergence is a major factor limiting crop yield, especially in hot climates where soil dries quickly after rainfall or irrigation. Problems with the emergence of cotton in Pakistan are of particular importance because of the high value of the crop and its contribution to national economy. A complex interaction of factors involving climate, seed properties, soil physical properties and soil management determine crop emergence and hence establishment. This means modelling of emergence is an important way of determining the combination of conditions at which emergence becomes limited. The studies reported here show the effect of temperature, matric potential and mechanical impedance on pre-emergent root and shoot growth of cotton variety MNH-147. The effect of osmotic potential and temperature on time to germination and cumulative germination of cotton is also described with some preliminary work on wheat. Finally a small field experiment was performed in Pakistan to identify major factors limiting emergence and provide data for future validation of a computer model of emergence. Time to germination was found to be a function of temperature and metric potential. It reduced with increase in temperature and osmotic potential. A linear relationship between temperature and germination rate (1/time to germination) indicated a base temperature of 9.8 °C. Germination rate also decreased linearly with decreasing osmotic potential between zero and -500 kPa. Thus the concept of hydrothermal time can be used to model germination and parameters to fit this model were determined. Root and shoot lengths of pre-emergent cotton seedling increased with increase in temperature from 22 to 32 °C but were reduced with a further increase to 38 °C. At any temperature, lengths increased linearly with time at a rate controlled by temperature. During the first 192 h after germination, growth was divided into two distinct phases: a linear increase with time followed by no further growth.

Stratigraphic studies of layers of volcanic ash, or tephra, in buried soils have been used to date accurately Holocene glacier fluctuations in Southern Iceland. 132 stratigraphic sections up to 11m deep, and containing up to 78 tephra layers, were logged to a resolution of 0.25cm. The chronological framework was completed with 12 radiocarbon dates, and by examing the association of the tephra stratigraphy with moraines representing former ice margins, a chronology of Holocene glacier fluctuations was constructed. The forelands of five glaciers were studied: Seljavallajokull, Gigjokull and Steinholtsjokull (outlets of Eyjafjallajokull) and Solheimajokull and Klifurarjokull (outlets of Myrdalsjokull). This study has shown for the first time that large glaciers existed in mid-Holocene Iceland because after 700 BP and before 4500 BP Solheimajokull extended at least 4km beyond its present limits, and terminated at less than 100m above sea level. Other major advances of this glacier culminated before 3100 BP, and between 1400-1200 BP. In the tenth century AD Solheimajokull was also longer than during the late Little Ice Age (1700-1900 AD). In contrast, Klifurarjokull and all the outlets of Eyjafjallajokull reached a maximum Holocene extent during the late Little Ice Age. It is proposed that the anomalous behaviour of Solheimajokull may be explained as a result of catchment changes caused by the growth of the Myrdalsjokull ice cap. The great human impact on the landscape since the Norse Settlement (c870-930 AD) has also been assessed as a result of the extensive study of the aeolian sediments lying between numerous, accurately dated tephra layers. These studies show that a zone of chronic soil erosion developed in the natural upland pastures immediately after the Norse Settlement and slowly swept down hill to reach lowlying areas during the last 400 years.

This investigation deals with the influence of initial curing periods and different curing environments, similar to those found in Middle Eastern countries, on the pore size distribution, permeability, water absorption and compressive strength of cement mortars and concretes made with and without pulverized fuel ash (pfa) and ground granulated blast-furnace slag (ggbs). Three 00 environments were chosen as follows: 1) 20C+70%RH, 2) 35C+70%RH, and 3) 45C+30%RH. To simulate in-place casting, the initial mix temperatures were controlled to be as close as possible to that of the environment in which the mixes were to be kept and moisture loss was allowed to occur from only the top-as-cast face of the specimen. Durability of the mortar specimens was assessed using pore size distribution, oxygen permeability, air permeability and water absorption. In addition to strength, the following tests were carried out on the concrete specimens to assess durability: initial surface absorption (ISAT), water absorption,relative air permeability and porosity. An the tests carried out on all specimens were undertaken at an age of 28 days. 7be test results showed that the durability properties of all specimens were significantly improved as curing periods increased. While curing durations had some significant effect on the strength of OPC/ggbs samples, the effects on OPC and OPC/pfa were in general only minimal. Furthermore, as to the effects on the pore size distribution and permeability, a critical curing duration (beyond which no further significant changes in these properties were observed) was seen to exist which depended on both curing environment and cement type. Enviromnents hotter than 20C+70%RH adversely affected the durability properties of uncured samples of all mixes. Furthermore, the durability properties of plain OPC samples were adversely affected by the two hot environments when compared to 20C+70%RH for all curing durations. On the other hand, while OPC/pfa and OPC/ggbs samples cured for one day or more at 35C+70%RH showed similar or worse durability results compared with those cured at 20C+ 70%RH, better results were obtained at 45C+30%RH than in either of the other two environments. As to the effects on strength, for any given curing period, environments hotter than 20C +70%RH adversely affected the OPC and OPC/ggbs samples but not those containing pfa. AT 20C+70%RH,the pfa specimens showed generally similar or worse durability results and weaker samples than plain OPC for all curing periods. This trend was reversed in the two hot environments. On the other hand, while OPC/ggbs samples showed similar or worse durability results at 20C+70%RH and 35OC+70%RH compared to plain OPC, at 450C+30%RH the slag specimens showed better durability results for curing periods of one day or more. Tbe 28-day strength of OPC and OPC/ggbs concretes were similar to each other in all envimnments for all curing periods except for those which were uncured. The uncured OPC specimens were stronger than the slag specimens in all envimnments.

No description available.

No description available.