Modelling and Structural Studies of a Gelling Polysaccharide: Agarose.

This thesis details work carried out over a period of three years on the two gelling carbohydrates agarose and carrageenan. The major part of the work deals with agarose. Two approaches have been used which yield information from different angles; these are the experimental (laboratory) and the simulation (computational) approaches. There is a large field of interest in gelling carbohydrates from the point of view of the food industry. Their extraordinary ability to form stable gels and emulsions incorporating other food ingredients makes them important in many deserts and dairy products. In the present work, models for agarose and carrageenan carbohydrates were developed using structural x-ray data and related carbohydrate literature. The models were treated with two different solvent simulation methods. It was found that the inclusion of individual solvent molecules (the closest approximation to a real solution) was extremely uneconomical when the demands on computing time were taken into account, and in fact the long term outcome of the simulation was the same for both methods. Inclusion of solvent simply reduces diffusion rates and the time constant for chain flexing. Gel permeation chromatography and differential scanning calorimetry were used to prepare samples of agarose molecules of known size, and to probe temperature dependent phase transitions. This work was done at the UNILEVER laboratories at Colworth House, Sharnbrook in Bedfordshire. It was found that only molecules longer than fifteen residues displayed the molecular ordering transition typical of agarose polymer, and a value for the enthalpy of the transition of -1.5kcal per mole of residues was measured. It was predicted that in agarose itself, helical regions of a size of approximately 40 residues should exist. Simulations were then done on several agarose molecules of different sizes in order to parallel the experimental work. The differences in energy between molecules in various conformations were compared. These results were also related to helix-coil transition theory. The modelling predicts an enthalpy per mole of residues for the agarose coil to helix transition of approximately -2kcal, and indicates that single agarose coils may be of some importance in agarose gel structure. The work illustrates the difficulty in modelling such complex systems, and in fact it remains impossible to observe agarose molecules undergoing the transition between a random coil and a helical conformation

Microplastics in European sea salts – An example of exposure through consumer choice and of interstudy methodological discrepancies

Microplastics are contaminants of emerging concern, not least due to their global presence in marine surface waters. Unsurprisingly, microplastics have been reported in salts harvested from numerous locations. We extracted microplastics from 13 European sea salts through 30% H2O2 digestion and filtration over 5-µm filters. Filters were visually inspected at magnifications to x100. A subsample of potential microplastics was subjected to Raman spectroscopy. Particle mass was estimated, and human dose exposure calculated. After blank corrections, median concentrations were 466 ± 152 microplastics kg-1 ranging from 74 to 1155 items kg-1. Traditionally harvested salts contained fewer microplastics than most industrially harvested ones (t-test, p < 0.01). Approximately 14 µg of microplastics (< 12 particles) may be absorbed by the human body annually, of which a quarter may derive from a consumer choosing sea salt. We reviewed existing studies, showing that targeting different particle sizes and incomplete filtrations hinder interstudy comparison, indicating the importance of method harmonisation for future studies. Excess salt consumption is detrimental to human health; the hazardousness of ingesting microplastics on the other hand has yet to be shown. A portion of microplastics may enter sea salts through production processes rather than source materials

On the Four Types of Weight Functions for Spatial Contiguity Matrix

This is a "spatial autocorrelation analysis" of spatial autocorrelation. I use the 1-dimension spatial autocorrelation function (ACF) and partial autocorrelation function (PACF) to analyze four kinds of weight function in common use for the 2-dimensional spatial autocorrelation model. The aim of this study is at how to select a proper weight function to construct a spatial contiguity matrix for spatial analysis. The scopes of application of different weight functions are defined in terms of the characters of their ACFs and PACFs.Comment: 8 pages, 5 figures, 2 table

Inferring the Scale of OpenStreetMap Features

International audienceTraditionally, national mapping agencies produced datasets and map products for a low number of specified and internally consistent scales, i.e. at a common level of detail (LoD). With the advent of projects like OpenStreetMap, data users are increasingly confronted with the task of dealing with heterogeneously detailed and scaled geodata. Knowing the scale of geodata is very important for mapping processes such as for generalization of label placement or land-cover studies for instance. In the following chapter, we review and compare two concurrent approaches at automatically assigning scale to OSM objects. The first approach is based on a multi-criteria decision making model, with a rationalist approach for defining and parameterizing the respective criteria, yielding five broad LoD classes. The second approach attempts to identify a single metric from an analysis process, which is then used to interpolate a scale equivalence. Both approaches are combined and tested against well-known Corine data, resulting in an improvement of the scale inference process. The chapter closes with a presentation of the most pressing open problem

Co-production in distributed generation:Renewable energy and creating space for fitting infrastructure within landscapes

This review describes the infrastructural elements of the socio-technical system of power supply based on renewables and the role of landscape concerns in decision-making about emerging ‘intelligent grids’. The considerable land areas required for energy infrastructure call for sizable ‘distributed generation’ close to energy consumption. Securing community acceptance of renewables’ infrastructure, perceived impacts on the community, and ‘landscape justice’ requires two types of co-production: in power supply and in making space available. With co-production, landscape issues are prominent, for some options dominant. However, ‘objectification’ of landscape, such as the use of ‘visibility’ as proxy for ‘visual impact’, is part of lingering centralised and hierarchical approaches to the deployment of renewables. Institutional tendencies of centralisation and hierarchy, in power supply management as well as in siting, should be replaced by co-production, as follows from common pool resources theory. Co-production is the key to respecting landscape values, furthering justice, and achieving community acceptance

A comparison of the health benefits of reduced-exertion high-intensity interval training (REHIT) and moderate-intensity walking in type 2 diabetes patients

Reduced-exertion high-intensity interval training (REHIT) is a genuinely time-efficient intervention that can improve aerobic capacity and insulin sensitivity in sedentary individuals. The present study compared the effects of REHIT and moderate-intensity walking on health markers in patients with type 2 diabetes (T2D) in a counter-balanced crossover study. Sixteen men with T2D (mean &plusmn; SD age: 55 &plusmn; 5 years, body mass index: 30.6 &plusmn; 2.8 kg&middot;m&minus;2, maximal aerobic capacity: 27 &plusmn; 4 mL&middot;kg&minus;1&middot;min&minus;1) completed 8 weeks of REHIT (three 10-min low-intensity cycling sessions/week with two &ldquo;all-out&rdquo; 10&ndash;20-s sprints) and 8 weeks of moderate-intensity walking (five 30-min sessions/week at an intensity corresponding to 40%&ndash;55% of heart-rate reserve), with a 2-month wash-out period between interventions. Before and after each intervention, participants underwent an incremental fitness test, an oral glucose tolerance test (OGTT), a whole-body dual-energy X-ray absorptiometry scan, and continuous glucose monitoring. REHIT was associated with a significantly larger increase in maximal aerobic capacity compared with walking (7% vs. 1%; time &times; intervention interaction effect:p&lt; 0.05). Both REHIT and walking decreased resting mean arterial pressure (&minus;4%; main effect of time:p&lt; 0.05) and plasma fructosamine (&minus;5%; main effect of time:p&lt; 0.05). Neither intervention significantly improved OGTT-derived measures of insulin sensitivity, glycaemic control measured using continuous glucose monitors, blood lipid profile, or body composition. We conclude that REHIT is superior to a 5-fold larger volume of moderate-intensity walking in improving aerobic fitness, but similar to walking REHIT is not an effective intervention for improving insulin sensitivity or glycaemic control in T2D patients in the short term

Unified View of Scaling Laws for River Networks

Scaling laws that describe the structure of river networks are shown to follow from three simple assumptions. These assumptions are: (1) river networks are structurally self-similar, (2) single channels are self-affine, and (3) overland flow into channels occurs over a characteristic distance (drainage density is uniform). We obtain a complete set of scaling relations connecting the exponents of these scaling laws and find that only two of these exponents are independent. We further demonstrate that the two predominant descriptions of network structure (Tokunaga's law and Horton's laws) are equivalent in the case of landscapes with uniform drainage density. The results are tested with data from both real landscapes and a special class of random networks.Comment: 14 pages, 9 figures, 4 tables (converted to Revtex4, PRE ref added