Physico-chemical controls on phosphorus cycling in two lowland streams. Part 2 - The sediment phase

This article investigates the temporal and spatial controls on sediment-phosphorus (P) dynamics in two contrasting sub-catchments of the River Kennet, England. Suspended sediment (collected under representative flow conditions) and size-fractionated bedload (collected weekly for one year) from the Rivers Lambourn and Enborne was analysed for a range of physico-chemical determinands. Total P concentrations were highest in the most mobile fractions of sediment: suspended sediment, fine silt and clay and organic matter (mean concentrations of 1758, 1548 and 1440 mug P g(-1) dry sediment, respectively). Correlation analysis showed significant relationships between total P and total iron (n = 110), total manganese (n = 110), organic matter (n = 110) and specific surface area (n = 28) in the Lambourn (r(2) 0.71, 0.68, 0.62 and 0.52, respectively) and between total P and total iron (n = 110), total manganese (n = 110) and organic matter (n = 110) in the Enborne (r(2) 0.74, 0.85 and 0.68, respectively). These data highlight the importance of metal oxyhydroxide adsorption of P on fine particulates and organic matter. However, high total P concentrations in the granule gravel and coarse sand size fraction during the summer period (mean concentration 228 mug P g(-1) dry sediment) also highlight the role of calcite co-precipitation on P dynamics in the Lambourn. P to cation ratios in Lambourn sediment indicated that fine silt and clay and granule gravel and coarse sand size fractions were potential sources of P release to the water column during specific periods of the summer and autumn. In the Enborne, however, only the granule gravel and coarse sand size fraction had high ratios and a slow, constant release of P was observed. In addition, scanning electron microscopy work confirmed the association of P with calcite in the Lambourn and P with iron on clay particles in the Enborne. The study highlighted the importance of the chemical and physical properties of the sediment in influencing the mechanisms controlling P storage and release within river channels. (C) 2004 Elsevier B.V. All rights reserved.

Non-commutative symbolic coding

We give a non-commutative generalization of classical symbolic coding in the presence of a synchronizing word. This is done by a scattering theoretical approach. Classically, the existence of a synchronizing word turns out to be equivalent to asymptotic completeness of the corresponding Markov process. A criterion for asymptotic completeness in general is provided by the regularity of an associated extended transition operator. Commutative and non-commutative examples are analysed.

The strategy makers: thoughts on war and society from Machiavelli and Clausewitz

Introductory chapter. Introduction and excerpts from works of Seigneur de Fourquevaux (1548); Francois Loque – Saillans (1589); Matthew Sutcliffe (1593); Don Bernardino de Mendoza (1595); Paul Hay du Chastelet (1668); Marquis Santa Cruz de Marcenado & Zanthier (1724-30/1775); Guibert (1772); Rühle von Lilienstern (1816/1817).

Spatial and radiometric fidelity of airborne multispectral imagery in the context of land-cover change analyses

The goal was to quantitatively estimate and compare the fidelity of images acquired with a digital imaging system (ADAR 5500) and generated through scanning of color infrared aerial photographs (SCIRAP) using image-based metrics. Images were collected nearly simultaneously in two repetitive flights to generate multi-temporal datasets. Spatial fidelity of ADAR was lower than that of SCIRAP images. Radiometric noise was higher for SCIRAP than for ADAR images, even though noise from misregistration effects was lower. These results suggest that with careful control of film scanning, the overall fidelity of SCIRAP imagery can be comparable to that of digital multispectral camera data. Therefore, SCIRAP images can likely be used in conjunction with digital metric camera imagery in long-term landcover change analyses.

Consideration of persuasive technology on users acceptance of e-commerce: exploring perceived persuasiveness

Persuasive technologies, used within in the domain of interactive technology, are used broadly in social contexts to encourage customers towards positive behavior change. In the context of e-commerce, persuasive technologies have already been extensively applied in the area of marketing to enhancing system credibility, however the issue of ‘persuasiveness’, and its role on positive user acceptance of technology, has not been investigated in the technology acceptance literature. This paper reviews theories and models of users’ acceptance and use in relation with persuasive technology, and identifies their limitation when considering the impact of persuasive technology on users’ acceptance of technology; thus justifying a need to add consideration of ‘perceived persuasiveness’. We conclude by identifying variables associated with perceived persuasiveness, and suggest key research directions for future research.

Nonhuman empires

The themed section “Nonhuman Empires” contributes to a critique of anthropocentrism in the field of imperial history. It reveals the variety of ways in which the historical trajectories of nonhuman animals and empires both intersected and informed one another. Beyond merely rehabilitating nonhuman themes in conversations about imperial history, it provides a platform for rethinking both nonhumans and empires as they are envisioned conventionally in the historiography. This introductory article begins by situating this special section as a conversation between science studies and animal studies, on the one hand, and the historiography of empires, on the other. It then suggests ways to reconceptualize agency, subjects, nonhumans, and empire by combining certain shared concerns of subaltern studies and actor-network theory. Finally, it emphasizes the need to integrate postcolonial critiques with emerging scholarship about the posthuman.