Tie-breaking in Hoeffding trees

A thorough examination of the performance of Hoeffding trees, state-of-the-art in classification for data streams, on a range of datasets reveals that tie breaking, an essential but supposedly rare procedure, is employed much more than expected. Testing with a lightweight method for handling continuous attributes, we find that the excessive invocation of tie breaking causes performance to degrade significantly on complex and noisy data. Investigating ways to reduce the number of tie breaks, we propose an adaptive method that overcomes the problem while not significantly affecting performance on simpler datasets

"So bigge as bigge may be": tracking size and shape change in domestic livestock in London (AD 1220-1900)

This study presents the analysis of 7966 individual cattle, sheep, pig and domestic hen bone measurements from 105 sites excavated in London dating to the period AD 1220–1900. Multiple episodes of size change are identified, although the speed and timing varies by species. The earliest evidence for size change in cattle and sheep occurs in the early 14th century and may be connected to the need to restock livestock populations following the outbreaks of murrain in the first half of that century. Subsequent size increases in livestock size may have occurred as a combined consequence of agricultural innovations in the wake of the Black Death, the increasing commercialisation of animal farming, as the meat requirements of an expanding London grew, and the rise of the ethic of improvement

Batch-Incremental Learning for Mining Data Streams

The data stream model for data mining places harsh restrictions on a learning algorithm. First, a model must be induced incrementally. Second, processing time for instances must keep up with their speed of arrival. Third, a model may only use a constant amount of memory, and must be ready for prediction at any point in time. We attempt to overcome these restrictions by presenting a data stream classification algorithm where the data is split into a stream of disjoint batches. Single batches of data can be processed one after the other by any standard non-incremental learning algorithm. Our approach uses ensembles of decision trees. These tree ensembles are iteratively merged into a single interpretable model of constant maximal size. Using benchmark datasets the algorithm is evaluated for accuracy against state-of-the-art algorithms that make use of the entire dataset

Mining data streams using option trees (revised edition, 2004)

The data stream model for data mining places harsh restrictions on a learning algorithm. A model must be induced following the briefest interrogation of the data, must use only available memory and must update itself over time within these constraints. Additionally, the model must be able to be used for data mining at any point in time. This paper describes a data stream classi_cation algorithm using an ensemble of option trees. The ensemble of trees is induced by boosting and iteratively combined into a single interpretable model. The algorithm is evaluated using benchmark datasets for accuracy against state-of-the-art algorithms that make use of the entire dataset

Cache Hierarchy Inspired Compression: a Novel Architecture for Data Streams

We present an architecture for data streams based on structures typically found in web cache hierarchies. The main idea is to build a meta level analyser from a number of levels constructed over time from a data stream. We present the general architecture for such a system and an application to classification. This architecture is an instance of the general wrapper idea allowing us to reuse standard batch learning algorithms in an inherently incremental learning environment. By artificially generating data sources we demonstrate that a hierarchy containing a mixture of models is able to adapt over time to the source of the data. In these experiments the hierarchies use an elementary performance based replacement policy and unweighted voting for making classification decisions

The THES university rankings: are they really world class? / Richard Holmes

The Times Higher Education Supplement (THES) international ranking of universities, published in 2004 and 2005, has received a great deal of attention throughout the world, nowhere more so than in East and Southeast Asia. This paper looks at the rankings and concludes that they are deficient in several respects. The sampling procedure is not explained and is very probably seriously biased, the weighting of the various components is not justified, inappropriate measures of teaching quality are used, the assessment of research achievement is biased against the humanities and social sciences, the classification of institutions is inconsistent, there are striking and implausible changes in the rankings between 2004 and 2005 and they are based in one crucial respect on regional rather than international comparisons. It is recommended that these rankings should not be the basis for the development and assessment of national and institutional policies

The THE-QS world university rankings, 2004 – 2009 / Richard Holmes.

This paper reviews the origin, development and demise of the Times Higher Education Supplement (now Times Higher Education) – QS Quacquarelli Symonds (QS) World University Rankings between 2004 and 2009. It describes the structure and methodology of the rankings, their public impact and various criticisms that have been made. It also analyses changes that were introduced between 2005 and 2009 and concludes by noting the development of two distinct ranking systems by the magazine Times Higher Education (THE) and by its former partner, the consulting company Quacquarelli Symonds

Hydrophobic counter ion effects on the formation of mesh and reversed phases in the perfluorodecanoate/water system

The tetramethylammonium perfluorodecanoate (C10TMA)/water system forms both random, Mh1(0) and correlated mesh, Mh1(R[3 with combining macron]m) phases over a wide range of concentration and temperature. Whilst the random mesh phase is found in the ammonium homologue, the extensive correlated mesh phase seems to be a result of the hydrophobic nature of the tetramethylammonium (TMA) counter ion. In order to explore the reasons for the occurrence of these mesh phases and the effects of hydrophobic counter ions on phase structure the counter ion has been substituted by a series of increasing hydrophobicity namely butyltrimethylammonium (BTMA), dibutyldimethylammonium (DBDMA), and methyltributylphosphonium (MTBP). The phases and their structures were identified by small angle X-ray scattering. Increasing counter ion hydrophobicity causes a change from mesh, to lamellar, and finally to reversed phases. All the hydrophobic counter ions are strongly bound to the water/fluorocarbon interface and, in the case of those with butyl chains, there is penetration of between 50 and 60% of the total number of counter ion methyl groups into the fluorocarbon region of the lamellar phase. These bound counter ions reduce the accessibility of the head group region to solvent water. As the number of butyl chains on the counter ion increases the lamellar phase is progressively lost and is replaced by a reversed micelle phase either as a single phase or as part of an extensive two phase region

A method for increasing the iodine value of the saturated fatty acids

The work covered by this thesis was undertaken with the idea of finding a method whereby unsaturated oils, of the drying type (those having iodine values of one hundred fifty or above), could be made from the saturated fatty acids. After an exhaustive search of the literature no evidence was found that this means of producing the unsaturated acids had ever been developed. Work has been done on the chlorination products of the fatty acids, the processes being covered by patents. No evidence however was given as to the possible structure of these compounds --Introduction, page 1