Performance of an ideal turbine in an inviscid shear flow

Although wind and tidal turbines operate in turbulent shear flow, most theoretical results concerning turbine performance, such as the well-known Betz limit, assume the upstream velocity profile is uniform. To improve on these existing results we extend the classical actuator disc model in this paper to investigate the performance of an ideal turbine in steady, inviscid shear flow. The model is developed on the assumption that there is negligible lateral interaction in the flow passing through the disc and that the actuator applies a uniform resistance across its area. With these assumptions, solution of the model leads to two key results. First, for laterally unbounded shear flow, it is shown that the normalised power extracted is the same as that for an ideal turbine in uniform flow, if the average of the cube of the upstream velocity of the fluid passing through the turbine is used in the normalisation. Second, for a laterally bounded shear flow, it is shown that the same normalisation can be applied, but allowance must also be made for the fact that non-uniform flow bypassing the turbine alters the background pressure gradient and, in turn, the turbines ‘effective blockage’ (so that it may be greater or less than the geometric blockage, defined as the ratio of turbine disc area to cross-sectional area of the flow). Predictions based on the extended model agree well with numerical simulations approximating the incompressible Euler equations. The model may be used to improve interpretation of model-scale results for wind and tidal turbines in tunnels/flumes, to investigate the variation in force across a turbine and to update existing theoretical models of arrays of tidal turbines

Carnivoran Frugivory and its Effect on Seed Dispersal, Plant Community Composition, Migration, and Biotic Carbon Storage

Seed dispersal by animals is important for the ecology of plants. It is particularly important to understand which animals are involved and how they move seeds differently from one another. Some seed dispersers are understudied despite ample evidence they consume fruits and seeds. This includes animals commonly referred to as carnivores in the order Carnivora. The overall goal of my dissertation was to describe the extent and quality of seed dispersal by Carnivorans, estimate important aspects of seed dispersal for a specific Carnivoran, the coyote, and estimate how differences between a coyote and songbirds affect where plants will occur in the future and if that changes how much carbon plants store on the landscape. To achieve these goals, I first systematically reviewed existing research on frugivory and seed dispersal by Carnivorans. Then, I experimentally evaluated how long it takes for seeds to pass through a coyote, and if the consumption of seeds by coyotes negatively affects seed germination or viability. Finally, I modeled how differences in the distances that coyotes carry seeds vs. songbirds affect plant migrations. I found that Carnivoran frugivory and seed dispersal are common, involve many plant species, and occur worldwide across most ecosystems. Carnivorans also rarely damage seeds or hamper seed viability and germination when they consume and disperse seeds. Furthermore, I found that coyotes generally take between 4 and 24 hours to pass seeds from the fruits they consumed and deliver seeds to new landscapes without harming them. Given coyote travel speeds, these results suggest that coyotes regularly disperse seeds up to 5 km. This seed dispersal distance is substantially greater than songbirds and led to a 2.5 times larger expansion of where junipers grew in models extending 80 years into the future. Coyote seed dispersal would also result in 3.4 times greater conversion of grasslands and an increase total biotic carbon storage by 1.1 Pg. My findings show that understudied seed dispersers like Carnivorans can greatly impact plant ecology and ecosystem services and highlights the need for further studies on the impacts of Carnivora on seed dispersal

An empirical study on the preferred size of the participant information sheet in research

Background: Informed consent is a requirement for all research. It is not, however, clear how much information is sufficient to make an informed decision about participation in research. Information on an online questionnaire about childhood development was provided through an unfolding electronic participant sheet in three levels of information. \ud Methods: 552 participants, who completed the web-based survey, accessed and spent time reading the participant information sheet (PIS) between July 2008 and November 2009. The information behaviour of the participants was investigated. The first level contained less information than might be found on a standard PIS, the second level corresponded to a standard PIS, and the third contained more information than on a standard PIS. The actual time spent on reading the information provided in three incremental levels and the participants' evaluation of the information were calculated. \ud Results: 77% of the participants chose to access the first level of information, whereas 12% accessed the first two levels, 6% accessed all three levels of information and 23% participated without accessing information. The most accessed levels of information were those that corresponded to the average reading times. \ud Conclusion: The brief information provided in the first level was sufficient for participants to make informed decisions, while a sizeable minority of the participants chose not to access any information at all. This study adds to the debate about how much information is required to make a decision about participation in research and the results may help inform the future development of information sheets by providing data on participants' actual needs when deciding about questionnaire surveys.\u

British research in accounting and finance (2001–2007): the 2008 research assessment exercise

No abstract available

L1551NE - Discovery of a Binary Companion

L1551NE is a very young (class 0 or I) low-mass protostar located close to the well-studied L1551 IRS5. We present here evidence, from 1.3mm continuum interferometric observations at ~1'' resolution, for a binary companion to L1551NE. The companion, whose 1.3mm flux density is ~1/3 that of the primary component, is located 1.43'' (~230 A.U. at 160pc) to the southeast. The millimeterwave emission from the primary component may have been just barely resolved, with deconvolved size ~0.82"x0.70" (~131x112 A.U.). The companion emission was unresolved (<100 A.U.). The pair is embedded within a flattened circum-binary envelope of size ~5.4'' x 2.3'' (~860 x 370 A.U.). The masses of the three components (i.e. from the cicumstellar material of the primary star and its companion, and the envelope) are approximately 0.044, 0.014 and 0.023 Mo respectively.Comment: 8 pages, 1 figur

Using Rheo-Small-Angle Neutron Scattering to Understand How Functionalised Dipeptides Form Gels

We explore the use of rheo-small-angle neutron scattering as a method to collect structural information from neutron scattering simultaneously with rheology to understand how low-molecular-weight hydrogels form and behave under shear. We examine three different gelling hydrogel systems to assess what structures are formed and how these influence the rheology. Furthermore, we probe what is happening to the network during syneresis and why the gels do not recover after an applied strain. All this information is vital when considering gels for applications such as 3D-printing and injection

Disk-Loss and Disk Renewal Phases in Classical Be Stars II. Detailed Analysis of Spectropolarimetric Data

In Wisniewski et al. 2010, paper I, we analyzed 15 years of spectroscopic and spectropolarimetric data from the Ritter and Pine Bluff Observatories of 2 Be stars, 60 Cygni and {\pi} Aquarii, when a transition from Be to B star occurred. Here we anaylize the intrinsic polarization, where we observe loop-like structures caused by the rise and fall of the polarization Balmer Jump and continuum V-band polarization being mismatched temporally with polarimetric outbursts. We also see polarization angle deviations from the mean, reported in paper I, which may be indicative of warps in the disk, blobs injected at an inclined orbit, or spiral density waves. We show our ongoing efforts to model time dependent behavior of the disk to constrain the phenomena, using 3D Monte Carlo radiative transfer codes.Comment: 2 pages, 6 figures, IAU Symposium 27

Caring for patients with brain tumor: The patient and care giver perspectives

Background: Patients with brain tumors form a heterogeneous group in terms of clinical presentation and pathology. However, the impact of the disease on patients&rsquo; families is often more homogenous and frequently quite profound. A considerable body of literature is available on the management of brain tumors and recently, the National Institute for Clinical Excellence has developed guidelines on the care of brain tumor patients that should improve the overall outcome for the patient from both the disease and psychological aspects.Objectives: An increasing number of studies have attempted to address the impact of the disease on the care givers and relatives of these patients, but few have considered the problem simultaneously from both the patient&rsquo;s and care giver&rsquo;s perspective. In this study, we analyzed the psychosocial and general health of brain tumor patients and related this to the care givers.Materials and Methods: This is a questionnaire-based postal survey of 168 patients and their relatives. We examined how the health and psychological well-being of the caregiver may affect the quality of care.Results: There is significant physical, social, and psychosocial morbidity associated with caring for brain tumor patients. Patients worry about their care givers and this constitutes additional stress for the patient.Conclusions: No constructive and lasting improvement can be made to the quality of life of patients with brain tumor until the health and welfare of their care givers are factored into the care package. With better service to the patient, it is hoped that the burden of care will lighten for the care givers

Experiences of psychosocial and programme-related barriers to recovery in lifestyle interventions for noncommunicable diseases

Background: The majority of global deaths are due to noncommunicable diseases, largely preventable and treatable utilising behavioural interventions.Objectives: The study investigated patients’ experiences of a lifestyle intervention programme for noncommunicable diseases (NCDs), and the influence that psychosocial and programme-related barriers had on patients’ ability to improve their well-being.Methods: Fourteen patients with NCDs were interviewed before and on completion of a 12-week lifestyle intervention programme at a sports and exercise medicine clinic. Thematic analysis techniques were used to analyse interview data.Results: Patients described their experiences of NCDs diagnosis as traumatic, and their own relationship with their bodies and with the disorder(s) to be vulnerable and significantly challenging. Professional incompetence and unethical treatment were included as barriers to recovery. Barriers specifically relating to the programme included scheduling, as well as the online assessment component. Those reporting more premorbid psychosocial barriers were more likely to experience current complications, whether disease- or treatment-related, often emphasising the negative influence of programme and professional-related problems.Conclusion: Qualitative methodologies enabled the study to yield clinically relevant insights with respect to patients with NCDs. Accounting for the trauma and vulnerability experienced by this cohort may assist in the development of more patient-centred interventions and sustainable secondary prevention of NCDs.Keywords: chronic diseases of lifestyle; intervention evaluation; psychological risk factors; social support; professional conduc