1,485 research outputs found
A Review of the Monitoring of Market Power The Possible Roles of TSOs in Monitoring for Market Power Issues in Congested Transmission Systems
The paper surveys the literature and publicly available information on market power monitoring in electricity wholesale markets. After briefly reviewing definitions, strategies and methods of mitigating market power we examine the various methods of detecting market power that have been employed by academics and market monitors/regulators. These techniques include structural and behavioural indices and analysis as well as various simulation approaches. The applications of these tools range from spot market mitigation and congestion management through to long-term market design assessment and merger decisions. Various market-power monitoring units already track market behaviour and produce indices. Our survey shows that these units collect a large amount of data from various market participants and we identify the crucial role of the transmission system operators with their access to dispatch and system information. Easily accessible and comprehensive data supports effective market power monitoring and facilitates market design evaluation. The discretion required for effective market monitoring is facilitated by institutional independence.Electricity, liberalisation, market power, regulation
Oxygen Cost of Recreational Horse-Riding in Females
Version: as accepted for publication.BACKGROUND: The purpose of this study was to characterize the physiological demands of a riding session comprising different types of recreational horse riding in females. METHODS: Sixteen female recreational riders (aged 17 to 54 years) completed an incremental cycle ergometer exercise test to determine peak oxygen consumption (VOâpeak) and a 45-minute riding session based upon a British Horse Society Stage 2 riding lesson (including walking, trotting, cantering and work without stirrups). Oxygen consumption (VOâ), from which metabolic equivalent (MET) and energy expenditure values were derived, was measured throughout. RESULTS: The mean VOâ requirement for trotting/cantering (18.4 ± 5.1 ml·kgâ»Âč·minâ»Âč; 52 ± 12% VOâpeak; 5.3 ± 1.1 METs) was similar to walking/trotting (17.4 ± 5.1 ml·kgâ»Âč·minâ»Âč; 48 ± 13% VOâpeak; 5.0 ± 1.5 METs) and significantly higher than for work without stirrups (14.2 ± 2.9 ml·kgâ»Âč·minâ»Âč; 41 ± 12% VOâpeak; 4.2 ± 0.8 METs) (P = .001). CONCLUSIONS: The oxygen cost of different activities typically performed in a recreational horse riding session meets the criteria for moderate intensity exercise (3-6 METs) in females, and trotting combined with cantering imposes the highest metabolic demand. Regular riding could contribute to the achievement of the public health recommendations for physical activity in this population
Calculation of flight vibration levels of the AH-1G helicopter and correlation with existing flight vibration measurements
NASA-Langley is sponsoring a rotorcraft structural dynamics program with the objective to establish in the U.S. a superior capability to utilize finite element analysis models for calculations to support industrial design of helicopter airframe structures. In the initial phase of the program, teams from the major U.S. manufacturers of helicopter airframes will apply extant finite element analysis methods to calculate loads and vibrations of helicopter airframes, and perform correlations between analysis and measurements. The aforementioned rotorcraft structural dynamics program was given the acronym DAMVIBS (Design Analysis Method for Vibrations). Sikorsky's RDYNE Rotorcraft Dynamics Analysis used for the correlation study, the specifics of the application of RDYNE to the AH-1G, and comparisons of the predictions of the method with flight data for loads and vibrations on the AH-1G are described. RDYNE was able to predict trends of variations of loads and vibrations with airspeed, but in some instances magnitudes differed from measured results by factors of two or three to one. Sensitivities were studied of predictions to rotor inflow modeling, effects of torsional modes, number of blade bending modes, fuselage structural damping, and hub modal content
SCOLIOSIS: A REVIEW
School screening of adolescents reveals a high prevalence of mild rotational deformity. The objective of screening is to prevent serious deformity by regular review of these children, early recognition of progression and provision of spinal bracing for curves greater than 25°. Two per cent of students screened in the age range 11â13 years have curves greater than 10° but only two per thousand screened require active treatment. A programme of exercise combined with bracing until skeletal maturity is reached, obviates the need for major surgery. Indications for follow-up and treatment are reviewed, and some current concepts of the aetiology of idiopathic scoliosis are examined with particular emphasis on the relationship between scoliosis and growth
Investigation into the Ultrasonic Setting of Glass Ionomer Cements : Part II Setting Times and Compressive Strengths
The ultrasonic setting of glass ionomer cements (GIC) was discussed. It was observed that the ultrasonic setting resulted in improvements of compressive strength. An increase in the PAA molecular weight from PAA50 to PAA200 resulted in an increase in the strength, but with a further increase in the PAA molecular weight to PAA450, there was a reduction in the strength. Results show that the strength of the ultrasonically set materials after 1 day were close to the values for the 7 days chemically set samples
Dairy Ingredients for Chocolate and Confectionery Products.
End of Project ReportHigh free-fat, spray-dried powders were successfully
produced at a lower fat content (40% rather than 56%) using
ultrafiltration. Chocolates made from these powders had
improved flow properties and superior quality.
The stability, viscosity and firmness of toffees were improved
by optimising the casein, whey protein and lactose levels of
skim milk powders used in their manufacture.Department of Agriculture, Food and the Marin
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Retrievals of Riming and Snow Density From Vertically Pointing Doppler Radars
Retrievals of ice and snow are made from Ka- and W-band zenith-pointing Doppler radars at Hyytiala, Finland, during the snow experiment component of the Biogenic Aerosols: Effects on Clouds and Climate (2014) field campaign. In a novel optimal estimation retrieval, mean Doppler velocity is exploited to retrieve a density factor parameter, which modulates the mass, shape, terminal velocity, and backscatter cross sections of ice particles. In a case study including aggregate snow and graupel we find that snow rate and ensemble mean ice density can be retrieved to within 50% of in situ measurements at the surface using dual-frequency Doppler radar retrievals. While Doppler measurements are essential to the retrieval of particle density, the dual-frequency ratio provides a strong constraint on particle size. The retrieved density factor is strongly correlated with liquid water path, indicating that riming is the primary process by which the density factor is modulated. Using liquid water path as a proxy for riming, profiles classified as unrimed snow, rimed snow, and graupel exhibit distinct features characteristic of aggregation and riming processes, suggesting the potential to make estimates of process rates from these retrievals. We discuss the potential application of the technique to future satellite missions. Plain Language Summary Ground-based radar measurements of ice clouds and snow are used to estimate the size, number, and density of snowflakes. Doppler velocity measurements of particle fall speeds are used to estimate the mass and shape of the snow particles. The properties of snow estimated using radar compare well against measurements of particles at the surface and estimates of the amount of liquid water in the atmosphere; the presence of liquid water relates to the potential for riming, in which snowflakes increase in density and fall speed by collecting and freezing liquid droplets. More accurate estimates of snow density from ground-based and satellite radars help to improve global estimates of precipitation and snow accumulation and the representation of clouds and snow in weather and climate models.Peer reviewe
Doxycycline pharmacokinetics in the absence of renal function
Doxycycline pharmacokinetics in the absence of renal function. Doxycycline is a new tetracycline that is now in widespread clinical use. It differs from the other tetracycline drugs in many important respects including small daily dosage schedules, essentially complete upper gastrointestinal absorption and excretory characteristics that are independent of renal function. Our studies demonstrate that in anephric patients and patients with varying degrees of renal function the plasma tÂœ of biologically active doxycycline is not significantly extended and that in such a clinical situation the usual therapeutic regimen of the drug is necessary. Clearance rate of the compound from the systemic circulation by hemodialysis is only 10ml/min or less. In addition, our investigations identify the importance of the nonhepatic gastrointestinal pathway of elimination of doxycycline from the systemic circulation. Doxycycline therefore appears to be unique among the tetracyclines in that it may be utilized as a drug of choice for the therapy of systemic infections when a tetracycline compound is indicated in the clinical setting of impaired renal function.PharmacocinĂ©tique de la doxycycline en l'absence de fonction rĂ©nale. La doxycycline est une nouvelle tĂ©tracycline dont l'usage clinique est maintenant largement rĂ©pandu. Elle diffĂšre des autres tĂ©tracyclines Ă plusieurs Ă©gards importants parmi lesquels la faible posologie quotidienne, l'absorption totale dans la partie haute du tractus digestif et des modalitĂ©s d'excrĂ©tion indĂ©pendantes de la fonction rĂ©nale. Notre travail dĂ©montre que chez les sujets anĂ©phriques et les malades atteints d'insuffisance rĂ©nale de sĂ©vĂ©ritĂ© variable la demie vie de la doxycycline biologiquement active n'est pas significativement allongĂ©e et que dans ces situations cliniques les modalitĂ©s thĂ©rapeutiques habituelles sont nĂ©cessaires. La clearance du composĂ© observĂ©e au cours de l'hĂ©modialyse est Ă©gale ou infĂ©rieure Ă 10 ml/min. De surcroĂźt nos travaux identifient l'importance de la voie d'Ă©limination hĂ©patique non intestinale de la doxycycline. La doxycycline apparaĂźt donc ĂȘtre unique parmi les tĂ©tracyclines en ce sens qu'elle peut ĂȘtre utilisĂ©e comme une drogue de choix pour le traitment des infections systĂ©miques quand une tĂ©tracycline est indiquĂ©e et qu'il existe une altĂ©ration de la fonction rĂ©nale
Stochastic modelling of reaction-diffusion processes: algorithms for bimolecular reactions
Several stochastic simulation algorithms (SSAs) have been recently proposed
for modelling reaction-diffusion processes in cellular and molecular biology.
In this paper, two commonly used SSAs are studied. The first SSA is an
on-lattice model described by the reaction-diffusion master equation. The
second SSA is an off-lattice model based on the simulation of Brownian motion
of individual molecules and their reactive collisions. In both cases, it is
shown that the commonly used implementation of bimolecular reactions (i.e. the
reactions of the form A + B -> C, or A + A -> C) might lead to incorrect
results. Improvements of both SSAs are suggested which overcome the
difficulties highlighted. In particular, a formula is presented for the
smallest possible compartment size (lattice spacing) which can be correctly
implemented in the first model. This implementation uses a new formula for the
rate of bimolecular reactions per compartment (lattice site).Comment: 33 pages, submitted to Physical Biolog
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