The spatial patterns of beta-amyloid (Abeta) deposits and neurofibrillary tangles (NFT) in late-onset sporadic Alzheimer's disease

The spatial patterns of beta-amyloid (Abeta) deposits and neurofibrillary tangles (NFT) were studied in areas of the cerebral cortex in 16 patients with the late-onset, sporadic form of Alzheimer’s disease (AD). Diffuse, primitive, and classic Abeta deposits and NFT were aggregated into clusters; the clusters being regularly distributed parallel to the pia mater in many areas. In a significant proportion of regions, the sizes of the regularly distributed clusters approximated to those of the cells of origin of the cortico-cortical projections. The diffuse and primitive Abeta deposits exhibited a similar range of spatial patterns but the classic Abeta deposits occurred less frequently in large clusters >6400microm. In addition, the NFT often occurred in larger regularly distributed clusters than the Abeta deposits. The location, size, and distribution of the clusters of Abeta deposits and NFT supports the hypothesis that AD is a 'disconnection syndrome' in which degeneration of specific cortico-cortical and cortico-hippocampal pathways results in synaptic disconnection and the formation of clusters of NFT and Abeta deposits.

Using directional curvatures to visualize folding patterns of the GTM projection manifolds

In data visualization, characterizing local geometric properties of non-linear projection manifolds provides the user with valuable additional information that can influence further steps in the data analysis. We take advantage of the smooth character of GTM projection manifold and analytically calculate its local directional curvatures. Curvature plots are useful for detecting regions where geometry is distorted, for changing the amount of regularization in non-linear projection manifolds, and for choosing regions of interest when constructing detailed lower-level visualization plots.

Measuring the spatial arrangement patterns of pathological lesions in histological sections of brain tissue

The development of abnormal protein aggregates in the form of extracellular plaques and intracellular inclusions is a characteristic feature of many neurodegenerative diseases such as Alzheimer's disease (AD), Creutzfeldt-Jakob disease (CJD) and the fronto-temporal dementias (FTD). An important aspect of a pathological protein aggregate is its spatial topography in the tissue. Lesions may not be randomly distributed within a histological section but exhibit spatial pattern, a departure from randomness either towards regularity or clustering. Information on the spatial pattern of a lesion may be useful in elucidating its pathogenesis and in studying the relationships between different lesions. This article reviews the methods that have been used to study the spatial topography of lesions. These include simple tests of whether the distribution of a lesion departs significantly from random using randomized points or sample fields, and more complex methods that employ grids or transects of contiguous fields and which can detect the intensity of aggregation and the sizes, distribution and spacing of the clusters. The usefulness of these methods in elucidating the pathogenesis of protein aggregates in neurodegenerative disease is discussed.

What does the study of the spatial patterns of pathological lesions tell us about the pathogenesis of neurodegenerative disorders?

Discrete pathological lesions, which include extracellular protein deposits, intracellular inclusions and changes in cell morphology, occur in the brain in the majority of neurodegenerative disorders. These lesions are not randomly distributed in the brain but exhibit a spatial pattern, that is, a departure from randomness towards regularity or clustering. The spatial pattern of a lesion may reflect pathological processes affecting particular neuroanatomical structures and, therefore, studies of spatial pattern may help to elucidate the pathogenesis of a lesion and of the disorders themselves. The present article reviews first, the statistical methods used to detect spatial patterns and second, the types of spatial patterns exhibited by pathological lesions in a variety of disorders which include Alzheimer's disease, Down syndrome, dementia with Lewy bodies, Creutzfeldt-Jakob disease, Pick's disease and corticobasal degeneration. These studies suggest that despite the morphological and molecular diversity of brain lesions, they often exhibit a common type of spatial pattern (i.e. aggregation into clusters that are regularly distributed in the tissue). The pathogenic implications of spatial pattern analysis are discussed with reference to the individual disorders and to studies of neurodegeneration as a whole.

Patterns of networking in the innovation process:a comparative study of the UK, Germany and Ireland

The research reported in this paper arose from collaboration with Brian Ashcroft (Fraser of Allander Institute, University of Strathclyde) and Stephen Roper (Northern Ireland Economic Research Centre, Queen's University of Belfast). The author is, however, solely responsible for the views expressed. The following sections are included: -Introduction -An Economics Perspective on Innovation Networks -The Product Development Survey -Discussion: Innovation, Networks and Institutions -Conclusions -References Read More: http://www.worldscientific.com/doi/abs/10.1142/9781848161481_0005

Patterns of corporate governance and technical efficiency in Italian manufacturing

The purpose of this paper is to analyse the relationship between the corporate governance system and technical efficiency in Italian manufacturing. We use a non-parametric frontier technique (DEA) to derive technical efficiency measures for a sample of Italian firms taken from nine manufacturing industries. These measures are then related to the characteristics of the corporate governance system. Two of these characteristics turn out to have a positive impact on technical efficiency: the percentage of the company shares owned by the largest shareholder and the fact that a firm belongs to a pyramidal group. Interestingly, a trade-off emerges between these influences, in the sense that one is stronger in industries where the other is weaker. Copyright © 2007 John Wiley & Sons, Ltd.

Faculty perceptions and readership patterns of finance journals:a global view

Journal rankings are frequently used as a measure of both journal and author research quality. Nonetheless, debates frequently arise because journal rankings do not take into account the underlying diversity of the finance research community. This study examines how factors such as a researcher's geographic origin, research interests, seniority, and journal affiliation influence journal quality perceptions and readership patterns. Based on a worldwide sample of 862 finance academics, we find remarkable consistency in the rankings of top journals. For the remaining journals, perception of journal quality differs depending on the researcher's geographic origin, research interests, seniority, and journal affiliation.

The spatial patterns of pathological brain lesions in 12 patients with corticobasal degeneration

Corticobasal degeneration (CBD) is a rare and progressive neurological disorder characterised by the presence of ballooned neurons (BN) and tau positive inclusions in neurons and glial cells. We studied the spatial patterns of the BN, tau positive neurons with inclusions (tau + neurons), and tau positive plaques in the neocortex and hippocampus in 12 cases of CBD. All lesions were aggregated into clusters and in many brain areas, the clusters were distributed in a regular pattern parallel to the tissue boundary. In the majority of cortical areas, the clusters of BN were larger in the lower compared with the upper laminae while the clusters of tau + neurons were larger in the upper laminae. Clusters of BN and tau + neurons were either negatively correlated or not significantly correlated in the upper and lower cortical laminae. Hence, BN and tau + lesions in CBD exhibit similar spatial patterns as lesions in Alzheimer's disease (AD), dementia with Lewy bodies (DLB) and Pick's disease (PD). The location, sizes and distribution of the clusters in the neocortex suggest that the tau + lesions may be associated with the degeneration of the feedforward and the BN the feedback cortico-cortical and/or the efferent cortical pathways. © 2001 Elsevier Science Ireland Ltd. All rights reserved.