Approximate analytical solutions for porous catalysts with nonuniform activity

Using a novel finite integral transform technique, the problem of diffusion and chemical reaction in a porous catalyst with general activity profile is investigated theoretically. Analytical expressions for the effectiveness factor are obtained for pth order and Michaelis-Menten kinetics. Perturbation methods are employed to provide useful asymptotic solutions for large or small values of Thiele modulus and Biot number.

Pinch my wig or winch my pig: Spelling, spoonerisms and other language skills

Phonological processing skills have often been assumed to play a minimal role in skilled adult spelling despite evidence showing their importance in the development of spelling skills. The present study investigated the relationship between phonological awareness and spelling in adults. It was hypothesised that subjects demonstrating higher levels of spelling proficiency would also show superior phonological processing skills. This relationship was expected to be mediated by sound-spelling mapping knowledge. Given the irregularities of sound-spelling correspondences in English, it was also predicted that knowledge of orthographic conventions would be related to spelling competency. Two measures of each component skill were used on seventy three university students. As predicted, the importance of spelling-sound mapping skills in spelling were demonstrated, as was a relationship between phonological awareness and spelling-sound correspondences. In addition a moderate correlation was found between orthographic tasks and spelling performance. It was concluded that, among university students at least, phonological ability makes an important contribution to skilled adult spelling.

Spelling in adults: The role of reading skills and experience

One hundred university students completed tests of spelling production, vocabulary, reading comprehension, reading experience, and reading accuracy (ability to distinguish a previously read word from a similar distractor). Reading experience, as measured by an adaptation of the Author Recognition Test, and reading accuracy contributed to the prediction of spelling beyond the joint contribution of reading comprehension and vocabulary. The results are more consistent with a uni-process model of spelling based on the quality of word-specific orthographic learning, rather than with a dual-process account relying on both word-specific knowledge and rules.

Does a reading lexicon provide orthographic representations for spelling?

University students spelled low-frequency words to dictation and subsequently made lexical decisions to them. In Experiment I, lexical decisions were slower on words students had spelled incorrectly relative to words they had spelled correctly, and there A as a larger repetition benefit 101 incorrectly spelled words. In experiment 2, the latency advantage for items spelled correctly was replicated when words were presented for only 200 ms and also in a spelling recognition task, In Experiment 3. masked identity and form priming effects were similar for words that had been spelled correctly and incorrectly, Item spelling accuracy tracked word frequency effects in the way chat it combined with repetition and priming effects. we inter that an individuals learning with a word's orthography underlies word frequency and item spelling accuracy effects and that a single orthographic lexicon serves visual word recognition and spelling. (C) 2000 Elsevier Science (USA).

Approximate processing of massive continuous quantile queries over high-speed data streams

Quantile computation has many applications including data mining and financial data analysis. It has been shown that an is an element of-approximate summary can be maintained so that, given a quantile query d (phi, is an element of), the data item at rank [phi N] may be approximately obtained within the rank error precision is an element of N over all N data items in a data stream or in a sliding window. However, scalable online processing of massive continuous quantile queries with different phi and is an element of poses a new challenge because the summary is continuously updated with new arrivals of data items. In this paper, first we aim to dramatically reduce the number of distinct query results by grouping a set of different queries into a cluster so that they can be processed virtually as a single query while the precision requirements from users can be retained. Second, we aim to minimize the total query processing costs. Efficient algorithms are developed to minimize the total number of times for reprocessing clusters and to produce the minimum number of clusters, respectively. The techniques are extended to maintain near-optimal clustering when queries are registered and removed in an arbitrary fashion against whole data streams or sliding windows. In addition to theoretical analysis, our performance study indicates that the proposed techniques are indeed scalable with respect to the number of input queries as well as the number of items and the item arrival rate in a data stream.

Spelling in adults: The combined influences of language skills and reading experience

One hundred and twelve university students completed 7 tests assessing word-reading accuracy, print exposure, phonological sensitivity, phonological coding and knowledge of English morphology as predictors of spelling accuracy. Together the tests accounted for 71% of the variance in spelling, with phonological skills and morphological knowledge emerging as strong predictors of spelling accuracy for words with both regular and irregular sound-spelling correspondences. The pattern of relationships was consistent with a model in which, as a function of the learning opportunities that are provided by reading experience, phonological skills promote the learning of individual word orthographies and structural relationships among words.

A misspelt youth: Spelling and orthographic learning in university students as a function of spelling-sound consistency

Pseudowords with inconsistent vs. consistent spellings (e.g., nurch, with rhyme neighbours search, lurch & perch, vs. mish, with neighbours dish, wish) were presented with definitions for naming either twice or 6 times. In an oral spelling test, there were main and interactive effects of consistency and the number of training trials on accuracy and main effects only on response latency, with the improvement in accuracy from 2 to 6 training trials greater for the more poorly learned inconsistent items. Of most interest, the smaller effect of training on accuracy in the consistent condition was reliable; contrary to the most obvious prediction of dual route spelling models that the sublexical procedure should produce correct spellings for consistent items early in training. In a second task students wrote spellings of multisyllabic words containing unstressed indeterminate (schwa) vowels. In their errors on the schwa vowel, students showed sensitivity to the most common spelling overall but also they were influenced by differences in schwa spellings in English words as a function of the number of syllables and schwa position. These results indicate that dual route models of spelling will need to accommodate the consistency of spellings within categories defined by lexical structure variables.

Dissolution of a solid sphere in an unbounded, stagnant liquid

An exact analytical solution is obtained for the transient dissolution of solid spheres in a diffusion-controlled environment. This result provides a useful reference point for drug testing in humans. The dimensionless solution is expressed in terms of a single parameter, which accounts for solubility, bulk flow, and stagnant fluid composition. A simple, explicit and exact expression was found to predict time-to-complete dissolution (TCD). An approximate solution was also found which tracks the exact case for low solubility conditions.

A finite integral transform technique for solving the diffusion-reaction equation with Michaelis-Menten kinetics

An approximate analytical technique employing a finite integral transform is developed to solve the reaction diffusion problem with Michaelis-Menten kinetics in a solid of general shape. A simple infinite series solution for the substrate concentration is obtained as a function of the Thiele modulus, modified Sherwood number, and Michaelis constant. An iteration scheme is developed to bring the approximate solution closer to the exact solution. Comparison with the known exact solutions for slab geometry (quadrature) and numerically exact solutions for spherical geometry (orthogonal collocation) shows excellent agreement for all values of the Thiele modulus and Michaelis constant.

A GIS Based Assessment of Land Suitable for Growing Hoop Pine in the Atherton, Eacham and Herberton Shires of North Queensland

The area of private land suitable and available for growing hoop pine (Araucaria cunninghamii) on the Atherton Tablelands in North Queensland was modelled using a geographic information system (GIS). In Atherton, Eacham and Herberton shires, approximately 64,700 ha of privately owned land were identified as having a mean annual rainfall and soil type similar to Forestry Plantations Queensland (FPQ) hoop pine growth plots with an approximate growth rate of 20 m3 per annum. Land with slope of over 25° and land covered with native vegetation were excluded in the estimation. If land which is currently used for high-value agriculture is also excluded, the net area of land potentially suitable and available for expansion of hoop pine plantations is approximately 22,900 ha. Expert silvicultural advice emphasized the role of site preparation and weed control in affecting the long-term growth rate of hoop pine. Hence, sites with less than optimal fertility and rainfall may be considered as being potentially suitable for growing hoop pine at a lower growth rate. The datasets had been prepared at various scales and differing precision for their description of land attributes. Therefore, the results of this investigation have limited applicability for planning at the individual farm level but are useful at the regional level to target areas for plantation expansion.

Analysis of heat transfer and entropy generation for a thermally developing Brinkman–Brinkman forced convection problem in a rectangular duct with isoflux walls

Heat transfer and entropy generation analysis of the thermally developing forced convection in a porous-saturated duct of rectangular cross-section, with walls maintained at a constant and uniform heat flux, is investigated based on the Brinkman flow model. The classical Galerkin method is used to obtain the fully developed velocity distribution. To solve the thermal energy equation, with the effects of viscous dissipation being included, the Extended Weighted Residuals Method (EWRM) is applied. The local (three dimensional) temperature field is solved by utilizing the Green’s function solution based on the EWRM where symbolic algebra is being used for convenience in presentation. Following the computation of the temperature field, expressions are presented for the local Nusselt number and the bulk temperature as a function of the dimensionless longitudinal coordinate, the aspect ratio, the Darcy number, the viscosity ratio, and the Brinkman number. With the velocity and temperature field being determined, the Second Law (of Thermodynamics) aspect of the problem is also investigated. Approximate closed form solutions are also presented for two limiting cases of MDa values. It is observed that decreasing the aspect ratio and MDa values increases the entropy generation rate.

High surface brightness dwarf galaxies in the Fornax cluster

We describe a search for compact dwarf galaxies in the Fornax cluster using the FLAIR spectrograph on the UK Schmidt Telescope. We measured radial velocities of 453 compact galaxies brighter than B-T approximate to 17.3 and found seven new compact dwarf cluster members that were not classified in previous surveys as members of the cluster. These are amongst the most compact, high surface brightness dwarf galaxies known. The inclusion of these galaxies in the cluster does not change the total luminosity function significantly, but they are important because of their extreme nature; one in particular appears to be a dwarf spiral. Three of the new dwarfs have strong emission lines and we identify them as blue compact dwarfs (BCDs), doubling the number of confirmed BCDs in the cluster. We also determined that none of the compact dwarf elliptical (M32-like) candidates is in the cluster, down to an absolute magnitude M-B = -13.2. We have investigated the claim of Irwin et al. that there is no strong relation between surface brightness and magnitude for the cluster members and find some support for this for the brighter galaxies (B-T < 17.3), but fainter galaxies still need to be measured.