Spatial and temporal variations in channel morphology, near-bed velocity, shear stress, bedload transport rate, pebble tracer movement, and bedload and bed material size distribution were measured in seven different channel patterns in two gravel-bed rivers in the Scottish Highlands (the Dubhaig and Feshie) and a proglacial stream in Norway (the Lyngsdalselva). The results showed that there were discernible links between the channel processes and changes which were consistent for all river types. 169 shear stress estimates from velocity profiles with changing discharge showed that Keller's (1971) velocity-reversal hypothesis holds true in different channel patterns of gravel-bed rivers and can be extended to include subunits of the pool/riffle cycle. At discharges near bankfull there is a decrease in the flow strength and amount of bedload movement from the poolhead down to the pooltail (and then riffle). On a broader scale 72 Helley-Smith bedload samples and the movement of over 3700 pebble tracers showed that the entrainment of different size fractions from heterogeneous bed material is inefficient and is overpredicted by the traditional bedload transport equations. Empirical analyses showed that when the armour is mobile/broken large and small particles have almost equal mobility as first proposed by Parker et al. (1982) and Andrews (1983). However for the majority of flow conditions the armour is static and entrainment is selective to a greater or lesser degree depending on the availability of appropriate-sized sediment at the surface and from bank erosion. The magnitude and direction of flow strength and bedload transport helps to explain the location and mode of channel development as revealed by repeated levelling and mapping. The accelerating convergent/decelerating divergent cells of flow alter the channel morphology in predictable ways. The positions of these cells can change with increasing discharge as the channel becomes generally, rather than locally, competent to move coarse sediment. The rates of bank erosion and volumetric scour and fill decreased from the active multi-braided system through to the stable straight channel type.

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When students are learning to read, the materials supplied typically will include extensive illustrations. The implicit assumption is that the inclusion of such illustrations will assist students in learning to read. Cognitive load theory suggests that this way of formatting learning materials may not be maximally effective as the inclusion of illustrations with written text constitutes redundant information that may interfere with learning. If working memory resources are devoted to the illustrations rather than the text, as is likely with young children, those resources will be unavailable to decipher the text. The elimination of redundant illustrations may thus enhance learning to read. Three experiments were conducted to investigate the effects of including illustrations in beginning reading materials. Experiment 1 compared reading materials consisting solely of simple prose passages with materials consisting of the same passages plus informative illustrations depicting the content of each passage. Reading proficiency improved more under the no illustrations condition. Experiment 2 compared the informative illustrations with uninformative illustrations. Reading proficiency improved more using uninformative illustrations. Experiment 3 compared uninformative illustrations with no illustrations and found no significant differences between these conditions. These results were interpreted within a cognitive load theory framework. It was concluded that informative illustrations are redundant and so impose an extraneous working memory load that interferes with learning to read.

To achieve goal-orientated behaviour, selective attention is often needed to filter out irrelevant information. Past research has shown that working memory (WM) plays a critical role in selective attention, with high WM load leading to more distractor interference than low WM load. However, because WM load is usually manipulated by requiring participants to hold in memory either one or several digits that were presented simultaneously while performing a selective attention task, the extent of attentional focus was not controlled. The present study examined the effect of WM load on distractor inhibition while keeping attentional focus constant by presenting one digit (low load condition) or six digits (high load condition) sequentially. The participants in the high-load condition demonstrated greater distractor interference than the participants in the low-load condition, suggesting that WM load influences distractor inhibition even when the extent of attentional focus was controlled. This result provides converging evidence to Lavie's (1995, 2005) load theory of attention and cognitive control.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1992. / Vita. Abstract. Includes bibliographical references (leaves 37-38). Also available via the Internet.

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1990. / Vita. Abstract. Bibliography. Also available via the Internet.

Thesis--California Institute of Technology. / Includes bibliographical references.

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2009. / Title from title screen (site viewed February 25, 2010). PDF text: ix, 363 p. : col. ill. ; 8 Mb. UMI publication number: AAT 3386590. Includes bibliographical references. Also available in microfilm and microfiche formats.

Thesis--California Institute of Technology. / Includes bibliographical references.

Thesis (Ph. D.)--University of Queensland, 2002. / Includes bibliographical references.