A correction to the enhanced bottom drag parameterisation of tidal turbines

Hydrodynamic modelling is an important tool for the development of tidal stream energy projects. Many hydrodynamic models incorporate the effect of tidal turbines through an enhanced bottom drag. In this paper we show that although for coarse grid resolutions (kilometre scale) the resulting force exerted on the flow agrees well with the theoretical value, the force starts decreasing with decreasing grid sizes when these become smaller than the length scale of the wake recovery. This is because the assumption that the upstream velocity can be approximated by the local model velocity, is no longer valid. Using linear momentum actuator disc theory however, we derive a relationship between these two velocities and formulate a correction to the enhanced bottom drag formulation that consistently applies a force that remains closed to the theoretical value, for all grid sizes down to the turbine scale. In addition, a better understanding of the relation between the model, upstream, and actual turbine velocity, as predicted by actuator disc theory, leads to an improved estimate of the usefully extractable energy. We show how the corrections can be applied (demonstrated here for the models MIKE 21 and Fluidity) by a simple modification of the drag coefficient

Measuring Part-Whole Bias: Some Evidence from Crop Biotechnology

We analyze the non-pecuniary aspects of some crop biotechnologies taken from three farm-level surveys. We focus particularly on the phenomen on of part-whole bias, which is the empirical finding that the sum of the stated part-worths (the value of each nonpecuniary characteristic) is greater than the stated total value of all the non-pecuniary characteristics. We analyze the empirical evidence of part-whole bias in the surveys, while decomposing it to further understand the phenomenon and to rescale the stated values of the non-pecuniary characteristics in the surveys. We find for all three surveys that the degree to which part-worths should be rescaled is about 60 percent.Crop Production/Industries, Research and Development/Tech Change/Emerging Technologies,

Chemometric modelling to relate antioxidants, neutral lipid fatty acids and flavour components in chicken breast

Relationships among quality factors in retailed free-range, corn-fed, organic, and conventional chicken breasts (9) were modeled using chemometric approaches. Use of principal component analysis (PCA) to neutral lipid composition data explained the majority (93%) of variability (variance) in fatty acid contents in 2 significant multivariate factors. PCA explained 88 and 75% variance in 3 factors for, respectively, flame ionization detection (FID) and nitrogen phosphorus (NPD) components in chromatographic flavor data from cooked chicken after simultaneous distillation extraction. Relationships to tissue antioxidant contents were modeled. Partial least square regression (PLS2), interrelating total data matrices, provided no useful models. By using single antioxidants as Y variables in PLS (1), good models (r2 values > 0.9) were obtained for alpha-tocopherol, glutathione, catalase, glutathione peroxidase, and reductase and FID flavor components and among the variables total mono and polyunsaturated fatty acids and subsets of FID, and saturated fatty acid and NPD components. Alpha-tocopherol had a modest (r2 = 0.63) relationship with neutral lipid n-3 fatty acid content. Such factors thus relate to flavor development and quality in chicken breast meat

Modeling Acreage Response and US Farm Policy In a New Market Environment

Replaced with revised version of poster 9/2/11.Agricultural and Food Policy,

Book reviews

Teaching/Communication/Extension/Profession,

The Psychosocial Occupational Therapy Competency Assessment (POT-CA): Development and Implementation in a Level I Fieldwork Course

A competency assessment was developed to assess students\u27 skills at the culmination of courses relating to mental health, including a Psychosocial Level I Fieldwork course. The intention of the assessment, titled the Psychosocial Occupational Therapy Competency Assessment (POT-CA), was to engage students in a practical skill demonstration and use of clinical reasoning in relation to brief case studies. Key skills assessed included: administration of the ACLS-5, establishing and maintaining therapeutic rapport, defining OT in client centered language, and use of clinical reasoning to identify additional assessment, intervention, and discharge recommendations. The purpose of this article is to present the tool and results from its preliminary use in a Level I psychosocial fieldwork course, in order to share a creative approach for assessing the development of clinical skills competence for mental health practice

Timing of Antiretroviral Therapy for HIV in the Setting of TB Treatment

The convergent human immunodeficiency virus (HIV) and tuberculosis (TB) pandemics continue to collectively exact significant morbidity and mortality worldwide. Highly active antiretroviral therapy (HAART) has been a critical component in combating the scourge of these two conditions as both a preemptive and therapeutic modality. However, concomitant administration of antiretroviral and antituberculous therapies poses significant challenges, including cumulative drug toxicities, drug-drug interactions, high pill burden, and the immune reconstitution inflammatory syndrome (IRIS), thus complicating the management of coinfected individuals. This paper will review data from recent studies regarding the optimal timing of HAART initiation relative to TB treatment, with the ultimate goal of improving coinfection-related morbidity and mortality while mitigating toxicity resulting from concurrent treatment of both infections

INTERACTION EFFECTS OF PROMOTION, RESEARCH, AND PRICE SUPPORT PROGRAMS FOR U.S. COTTON

Many agricultural commodities have industry-funded generic promotion and/or research ("checkoff") programs designed to improve the economic performance of producers. To determine the effectiveness of these programs, the net benefits to producers attributable to activities funded by the checkoff must be separated from those due to other factors influencing commodity markets. One such factor that is very important in many agricultural commodity markets is the effect of government programs. However, studies evaluating the returns to checkoff programs often do not explicitly discuss the impact of pre-existing distortions caused by federal farm programs. Because the distortions caused by farm programs can be quite large, this omission can lead to seriously biased estimates of the returns to the checkoff programs. In this study, we develop a model that captures the influence of two Federal programs (loan deficiency payments to farmers and subsidies to consuming mills) on the estimated returns to the Cotton Research and Promotion Program. Using an econometrically estimated model of the U.S. cotton market, we find that the program interaction effects have a large impact on checkoff program returns.Agricultural and Food Policy, Crop Production/Industries,