A comparison of organic and conventionally-produced lamb purchased from three major UK supermarkets: Price, eating quality and fatty acid composition

Organic and conventional lamb loin chops, labelled as British lamb, were bought from three major UK supermarket chains (designated A, B and C) in the Bristol area on 10 occasions over a six week period. Samples (n=360) were from unknown production systems but representative of what is available to UK consumers. The nutritional quality of muscle was assessed in terms of its fatty acid composition and eating quality was assessed by a trained sensory panel. Lamb prices varied between ￡9 and ￡12.50 per kg, with a relatively modest price differential between organic and conventional lamb chops of ￡1.10, ￡1.88 and ￡1.16 ￡/kg for supermarkets A, B and C, respectively. On average, organic chops were 20g heavier than conventional chops. Chops were relatively lean, having just 14% of subcutaneous fat, approximately half that of a similar survey 10 years ago. Organic lamb had a better eating quality than conventional lamb in terms of juiciness (p<0.05), flavour (p<0.05) and overall liking (p<0.05) thus providing some evidence for the perception among consumers that organic products 'taste better'. Differences in juiciness were attributed to the higher intramuscular fat content of organic meat whilst differences in flavour were attributed to differences in fatty acid composition, in particular, the higher level of linolenic acid (18:3) and total n-3 PUFA in organic chops. Conventional chops had a higher percentage of linoleic acid (18:2). Chops from both productions systems had a favourable n-6:n-3 ratio. The most important difference between the three supermarkets was that lamb flavour was significantly lower in chops from supermarket A, probably due to differences in their 'display until' dates. Chops from supermarket A were also the cheapest.     

Oxidative Instability of Fuels: Nickel Catalyzed Reactions

The reactions that lead to long-term storage instability of fuels are not fully understood. Various reports in the literature link particular fuels with specific reactions, usually oxidation or free radical processes. Trace quantities of metals are present in all processed fuels. The metal source can be naturally occurring or present from fuel handling. The usual case is to look at the reaction of the metal or metal ion with molecular oxygen or other active oxygen species such as hydroperoxides. This article reports on the reaction of a nitrogen heterocycle, indole. We propose a mechanism that shows that catalytic amounts of nickel can produce compounds of higher molecular weight and increased polarity.     

Texture of cooked potatoes: Relationship between the compressive strength of cooked potato disks and release of pectic substances

In experiments where the interaction of starch and cell size were kept to a minimum by taking identical material for each experiment (disks from the same tuber), the loss of compressive strength of potato tissue on cooking was found to be related to the release of pectic substances into the cooking liquor. This relationship was found to hold true whether large differences in compressive strength were produced by cooking the disks in water for varying lengths of time or by cooking disks in solutions of calcium or potassium chloride for fixed times. The release of starch into the cooking liquor was not related to loss of compressive strength when the results of a number of experiments from disks from the same tuber were compared. Increased cooking time, or the presence of potassium chloride in the cooking solution, reduced compressive strength and increased the amount of pectic substances released. The presence of calcium chloride had the reverse effect. It was not clear whether the effects of calcium chloride were due to calcium per se or the pH of the solutions after cooking, which were inversely related to calcium chloride concentration.     

FUEL INSTABILITY STUDIES: THE CHEMICAL VALIDATION OF ASTM METHOD D5304

The current ASTM (D5304) procedure for determining storage stability involves rather drastic conditions, namely, 16 hours at 90°C and under 100 psig of oxygen. These mandated test conditions give rise to the question, “Does the reaction conditions induce chemical instability, or is it an accurate measure of the true instability process?” Several organo-sulfur functional groups are known to be present in petroleum derived fuels. Thiophenes, benzothiophenes, sulfides, disulfides, and trace amounts of thiols are the organo-sulfur compounds most prevalent. The reaction of organo-sulfur compounds under the ASTM reaction conditions have not been investigated. The purpose of the present research is to determine if the ASTM reaction conditions induce a reaction in an otherwise stable fuel matrix.     

Reliability of thin ZrO2 gate dielectric layers

In this work we examine the positive bias temperature instability (PBTI) and stress induced leakage current (SILC) reliability of nFET devices with thin (2.5 nm) ZrO₂ gate dielectric layers. nFET devices show anomalous PBTI behavior in the form of a negative threshold voltage (V_t) shift during positive bias stress with little temperature dependence and it is not ‘frozen out’ at lower temperatures, indicating a single non-diffusion based mechanism. Correlations between the PBTI and the stress induced leakage current (SILC) suggest that the PBTI effect originates from trapping into empty defects which are initially detected as SILC and located just below the silicon conduction band. These defects also appear to be linked to the time dependent dielectric breakdown behavior.     

Influence of Tower Shadow and Wind Turbulence on the Performance of Power System Stabilizers for DFIG-Based Wind Farms

The aim of the paper is to demonstrate the way in which mechanical power variations, due to tower shadow and wind turbulence, influence control performance of power system stabilizer (PSS) loops for doubly-fed induction generators (DFIGs). The PSS auxiliary loops are applied on a specific DFIG control scheme, the flux magnitude and angle controller (FMAC). However, since the PSS signal is applied at the output of the basic controller, the PSS performance characteristics displayed are deemed typical for DFIG control schemes in general. The relative capabilities of PSS controllers based on stator power, rotor speed, and network frequency, when the DFIG turbine is subjected to aerodynamic torque variations, are investigated via simulation studies. A two-generator aggregate model of a wind farm is introduced, which enables the influence of tower shadow and wind turbulence on both an individual turbine and on the overall wind farm itself to be assessed.     

Nicotine dependence versus smoking prevalence: comparisons among countries and categories of smokers

OBJECTIVES: To collect available international data on nicotine dependence as defined by the Fagerstrom Test of Nicotine Dependence, and to compare levels of dependence among countries and categories of smokers. DATA SOURCES: Published and unpublished studies known to the authors and a search of EMBASE from 1985-1995. STUDY SELECTION: Studies included were those based on a nationally representative sample of a country's population, or a sample of smokers seeking cessation assistance. DATA SYNTHESIS: Smokers who seek help in stopping smoking are much more dependent than the average smoker. Men consistently score higher on dependence than women. Ex-smokers appear to have lower dependence than current smokers. A country with low smoking prevalence, the United States, seems to have smokers with higher dependence scores than countries where smoking is more prevalent (such as Austria and Poland). CONCLUSIONS: Successful tobacco control may result in a higher dependence among the remaining smokers (due to selective quitting by low-dependent smokers). The remaining highly dependent smokers may need more intensive treatment.


     

Technology learning for renewable energy: Implications for South Africa's long-term mitigation scenarios

Technology learning can make a significant difference to renewable energy as a mitigation option in South Africa's electricity sector. This article considers scenarios implemented in a Markal energy model used for mitigation analysis. It outlines the empirical evidence that unit costs of renewable energy technologies decline, considers the theoretical background and how this can be implemented in modeling. Two scenarios are modelled, assuming 27% and 50% of renewable electricity by 2050, respectively. The results show a dramatic shift in the mitigation costs. In the less ambitious scenario, instead of imposing a cost of Rand 52/t CO₂-eq (at 10% discount rate), reduced costs due to technology learning turn renewables into negative cost option. Our results show that technology learning flips the costs, saving R143. At higher penetration rate, the incremental costs added beyond the base case decline from R92 per ton to R3. Including assumptions about technology learning turns renewable from a higher-cost mitigation option to one close to zero. We conclude that a future world in which global investment in renewables drives down unit costs makes it a much more cost-effective and sustainable mitigation option in South Africa.     

Glycine propionyl-L-carnitine produces enhanced anaerobic work capacity with reduced lactate accumulation in resistance trained males

Background  

Recent research has indicated that short term administration of glycine propionyl-L-carnitine (GPLC) significantly elevates levels of nitric oxide metabolites at rest and in response to reactive hyperaemia. However, no scientific evidence exists that suggests such supplementation enhances exercise performance in healthy, trained individuals. The purpose of this study was to examine the effects of GPLC on the performance of repeated high intensity stationary cycle sprints with limited recovery periods in resistance trained male subjects.     

A numerical investigation into the effect of windvent dampers on operating conditions

The United Kingdom has made a commitment to reduce buildings carbon emissions, placing a greater onus on sustainable energy sources. Therefore, an anticipated increase of usage of zero carbon technologies in new and existing building has led to the emergence of passive ventilation devices as an alternative to mechanical ventilation and air conditioning. The windvent is a commercially available passive ventilation device. The device is constructed from sheet metal and works on the principle of pressure differential. Whereby air rises, creating a low pressure in the receiving room, which then draws in the fresh air. The ensuing air delivery velocity is controlled by the dampers, installed at the room entry interface. The dampers are actuator operated, and form the basis of the control system for the device. The purpose of this paper is to investigate the control mechanism for the device and ascertain an optimum operating range. Numerical analysis is carried out using a commercial computational fluid dynamics (CFD) code, to investigate the effect of various damper angles (range 0–90°). The results show that optimum operating occurs at a damper angle range of 45–55°, at the UK average 4.5 m/s external wind speed. The operating range when considered in tandem with macro climatic influences is central to determining the overall control strategy for the fresh air supply. The results provide useful information for both engineers and architects when examining ways to reduce new and existing buildings running costs, and conform to new legislation.