Competition in the British domestic gas market: efficiency and equity

The British domestic gas market is to be opened to competition from April 1996; within 24 hours of enabling legislation being confirmed (Queen’s Speech, 1994),British Gas (BG) announced the first significant change in gas tariff structure since it had been privatised nine years earlier. The changes introduced cheaper tariffs for some of those who paid promptly and so were cheaper for BG to supply. These are likely to be the first of many such changes, as the threat of competition leads BG to abandon its previous policy of charging similar tariffs to a wide range of consumers even when they incur different costs of supply. It is clear that competition will have a much more dramatic effect on domestic tariffs than did the flotation of the industry. While it retained its monopoly in the domestic market, even the privatised BG continued its policy of crosssubsidisation between consumers, using a single charging structure despite cost differences. (One reason for this may have been to avoid signalling cost

New data and the hard pomeron

New structure-function data are in excellent agreement with the existence of a hard pomeron, with intercept about 1.4. It gives a very economical description of the data. Having fixed 2 parameters from the data for the real-photon cross section $\sigma^{\gamma p}$, we need just 5 further parameters to fit the data for $F_2(x,Q^2)$ with $x\leq 0.001$. The available data range from $Q^2=0.045$ to 35 GeV$^2$. With guesses consistent with dimensional counting for the $x$ dependences of our three separate terms, the fit extends well to larger $x$ and to $Q^2=5000$ GeV$^2$. With no additional parameters, it gives a good description of data for the charm structure function $F_2^c(x,Q^2)$ from $Q^2=0$ to 130 GeV$^2$. The two pomerons also give a good description of both the $W$ and the $t$ dependence of $\gamma p\to J/\psi p$.Comment: 11 pages, plain tex, with 10 figures embedded using epsf. (Spurious figure removed.

Green leaf lipid extract as a yield stress modifying emulsifier in reduced-fat chocolate

Chocolate is a composite material of sugar and cocoa particles, sometimes also containing milk powder, in a crystallised fat phase of mostly cocoa butter. As a melt above 40°C, chocolate represents a highly-filled suspension, often formulated close to the maximum packing fraction, especially in the case of lower-fat recipes. Emulsifiers are added to control the rheological properties of chocolate through adsorption at the hydrophilic sugar surfaces, thus inhibiting aggregate formation in the hydrophobic continuous phase. The most commonly applied emulsifier is lecithin (E322). It reduces the viscosity of chocolate and can lower its yield stress. However, polyglycerol polyricinoleate (PGPR, E476) has a much more substantial yield stress lowering effect, unique amongst food-grade emulsifiers. Unfortunately, PGPR is label adverse, perhaps due to its unfamiliar and chemical-sounding name; PGPR has an E-number, and even though lecithin also does, its name is often used in the ingredients list instead, as consumers are more familiar with or even approve of “lecithin”; or perhaps consumers reject it due to the fact that it is “processed” from castor oil. Therefore, the overall aim of this PhD research was to determine a natural alternative that provides a similar yield stress lowering effect. To achieve this goal, the research set out to analyse five commercially available PGPR samples with observationally reported differences in yield stress lowering efficacy, generating analytical data to validate the empirically reported difference in functionality and analysing molecular make-up in order to understand the molecular characteristics that are present in more efficient PGPRs. This new knowledge was then exploited to select a natural molecule possessing the identified molecular properties and yield stress lowering properties comparable with PGPR. Initially, a chocolate model consisting of a 65% (wt) sugar-in-oil suspension, where the oil was pre-treated to remove naturally present surface-active molecules, and a rheology protocol to obtain yield stress data for these suspensions, with and without added emulsifier, was developed. The rheology protocol developed comprised the concentric cylinder geometry to perform a shear stress sweep from high to low stress values and data analysis to compute the Herschel-Bulkley (H-B) yield stress value to allow sample comparison. Applying the commercial PGPR samples at 0.3% (wt) (total sample weight) in the chocolate model revealed that the PGPRs could be separated into those more or less efficient at reducing yield stress, although all PGPRs reduced the yield stress significantly compared to the baseline samples with no added PGPR. The impact of PGPRs on the interfacial tension between treated oil and water was then investigated as a way of interrogating their surface-active character. It was found that the H-B yield stress values were directly proportional to critical micelle concentration data, determined from equilibrium interfacial tension values between water and the chocolate model oil phase with PGPR added at a range of concentrations. The data inferred that the PGPRs that were more efficient at lowering the yield stress probably had a larger hydrophilic head group and straight hydrophobic tails, thus enabling reverse micelle formation at a lower concentration of PGPR. Further analysis via electrospray ionisation-mass spectrometry and size exclusion chromatography revealed that the five PGPR samples were virtually indistinguishable from each other regarding their range of molecular weights. As a verification of this finding, analysis using 13C nuclear magnetic resonance on two samples, the least and most efficient yield stress reducing PGPR samples, showed that the polyricinoleate chain lengths appeared identical. Finally, transmethylation of the samples followed by gas chromatography-mass spectroscopy revealed that a significantly greater amount of ricinoleic acid molecules were present at the terminus of the polyricinoleate chains of the least efficient PGPR sample. Therefore, it was hypothesised that hydroxyl groups at the end fatty acid are attracted to the hydrophilic sugar causing the hydrophobic chain to fold back on itself. The long length of the polyricinoleate chain extending into the continuous phase has been shown in previous research to be essential in the yield stress reducing abilities of PGPR; therefore, any restriction on this chain is detrimental to its functionality. Since most natural polar lipids lack ricinolic acid, the molecular criterion selected to identify a possible alternative to PGPR was the large headgroup configuration of a glycerol-based molecule that separates the acyl chains; acylated monogalactosyl diacylglycerol (acyl-MGDG). Purified acyl-MGDG is commercially not available, so it was obtained in two ways. The enzyme identified as responsible for forming acyl-MGDG, named AGAP-1, was acquired and multiplied using recombinant protein expression technology. This enzyme was used to convert commercially available MGDG and DGDG into acyl-MGDG, validated by high-performance thin-layer chromatography (HPTLC). Only a very small quantity could be obtained, not allowing conclusive statements to be made concerning yield stress lowering efficacy. Alternatively, cocoa leaves were collected from cocoa farms in the Côte D’Ivoire, and the Eden Project biodomes, UK, and mechanically stressed to trigger the formation of acyl-MGDG. HPTLC revealed that both the stressed and the control cocoa leaf lipids contained acyl-MGDG and other acylated galactolipids. The presence of acyl-MGDG without mechanical or biotic stress has not been shown before; however, the leaves showed other signs of lipid breakdown with lower amounts of galactolipids, chlorophyll and carotenoids than expected for a leaf. It may be that the creation of acyl-MGDG is naturally occurring in all senescing leaves, whether or not they have had biotic or abiotic stress applied. The leaf lipids applied to the chocolate model at 0.15% (wt) showed a yield stress lowering ability that was statistically similar to 0.3% (wt) PGPR. This finding is promising for food-grade emulsifier development and one which deserves further development

Oral corticosteroids in asthma and beyond : moving forward

Peer reviewedPostprin

Increasing inter‐word spacing reduces migration errors and improves reading comprehension in students with dyslexia

We report a small study in which we explored the effects of manipulating narrative text on levels of comprehension for students with and without dyslexia. Using two pieces of standardised narrative text deemed to be of similar difficulty and length, we manipulated the texts such that we could present two texts to each participant, one in each condition. The first condition was text using standard inter‐word spacing; the second condition used increased inter‐word spacing. Scores on standardised comprehension questions were significantly improved for participants with dyslexia. Additionally, given that there is evidence of delayed visual attention disengagement in individuals with specific forms of dyslexia, we hypothesised that the phenomena of migration of letters and words for some readers might be mitigated by increasing inter‐word spacing. We did indeed find that incidence of migration was significantly reduced in this condition for all participants

Comparing a controlled levelled vocabulary with a language rich vocabulary in a beginner reading scheme

The primary aim of this research was to compare the effect of using vocabulary that is within a child’s current decoding ability in a reading text, with vocabulary that is beyond it. The original contribution to knowledge presented here is the discovery that children of all abilities and both genders can make greater gains in early reading when using reading books that go beyond their current phonic decoding ability (Intervention A), than from reading books that have a controlled, levelled vocabulary (Intervention P). The secondary aim of this research was to compare the use of a synthetic-phonics only approach with mixed teaching methods. Three separate, but related studies were completed in schools across two counties. In total, there were 16 schools and 372 children who participated (4 schools acting as controls). A novel reading intervention, which had been purposely developed for the research (weebee Reading Programme), was used in 12 classes randomised to one of two possible Intervention strands (A or P). Measures of word reading and comprehension were used at both pre-test and post-test. All three studies were carried out over a 12-month period, although they began at staggered intervals. The main findings were: first, children who used vocabulary that included many words which were beyond their current decoding ability, made greater gains in word decoding and comprehension than children using only vocabulary within their current decoding ability. Second, those children who had been taught using a mixed approach in addition to synthetic phonics made greater gains (particularly in comprehension) than those children taught using only synthetic phonics. In addition, gender analyses for all three studies, which included a small group of struggling readers, indicated greater gains for boys compared to girls, from using both the mixed approach to teaching as well as the non-decodable vocabulary