Estimating Variable Returns to Scale Production Frontiers with Alternative Stochastic Assumptions

A stochastic production frontier model is formulated within the generalized production function framework popularized by Zellner and Revankar (1969) and Zellner and Ryu (1998). This framework is convenient for parsimonious modeling of a production function with variable returns to scale specified as a function of output. Two alternatives for introducing the stochastic inefficiency term and the stochastic error are considered, one where they are appended to the existing equation for the production relationship and one where the existing equation is solved for the log of output before the stochastic terms are added. The latter alternative is novel, but it is needed to preserve the usual definition of firm efficiency. The two alternative stochastic assumptions are considered in conjunction with two returns to scale functions, making a total of four models that are considered. A Bayesian framework for estimating all four models is described. The techniques are applied to USDA state-level data on agricultural output and four inputs. Posterior distributions for all parameters, firm efficiencies and the efficiency rankings of firms are obtained. The sensitivity of the results to the returns to scale specification and to the stochastic specification is examined.

Seasonal migrations of the European sea bass (Dicentrarchus labrax L.) in UK and surrounding waters

The movements and behaviour of mature European sea bass (Dicentrarchus labrax L.) in UK waters have not been studied extensively since a series of mark-recapture experiments during the 1970s, 80s and 90s. To better understand the timing and extent of seasonal migrations, 171 mature sea bass > 42 cm were internally tagged with floated electronic tags programmed to record temperature and depth, and released in the English Channel, in the southern North Sea and in the Irish Sea. Among the 48 tags returned to date, sea bass were at liberty for 370 +/- 337 days and were recovered 172 +/- 200 km from their respective release locations. Most tags were recovered from beaches (54%), or via the fishery (44%). A comparison of the reconstructed tracks from returned electronic tags with the recapture locations of 237 mark-recapture returns (6.5%) from 3615 sea bass released between 1970 and 2020 showed strong overlap. Seasonal movements between shallow areas (Q2-Q3) and deeper spawning areas (Q4-Q1) were accompanied by elevated vertical swimming speeds and average water temperatures of 8.5 degrees C in the English Channel and Irish Sea, but lower temperatures in the North Sea. Movements between the Celtic Sea/Irish Sea and the North Sea and vice versa demonstrate high levels of connectivity in UK waters. We demonstrate that a proportion of sea bass remained resident within the North Sea throughout the year, with a strong suggestion that spawning might be occurring. These data have significant implications for the future sustainable management of sea bass stocks in UK and surrounding waters

Characterisation of solution-processable organic light emitting diodes

A range of new materials for organic light emitting diodes (OLEDs) synthesised in the Department of Chemistry at Durham University have been characterised and electroluminescent devices containing these materials have been optimised. High triplet oxadiazole based electron transport materials were tested in devices blended with the host material poly(9-vinylcarbazole) (PVK). The materials exhibit comparable performance to standard OXD-7 in electrophosphorescent devices, while emission from exciplex devices indicate the new materials have higher LUMO energies than OXD-7. Single layer devices containing new sky-blue iridium(III) emitters were optimised. The improved solubility of these emitters over FIrpic, the standard sky-blue emitter, resulted in improved device efficiency and brightness due to reduced aggregation, concentration quenching and self absorption in film, and higher radiative yield. Derivatives of these new emitters, with emission shifted towards a deeper blue, were characterised. Increased trapping by the PVK host led to a reduction in the device efficiency for these materials. Two series of iridium(III) emitters with emission tuned from green to red by systematically substituted electron withdrawing or donating groups were characterised. Photophysical properties of these emitters, including the solvatochromic shift of photoluminescence spectra, correlate with theoretical values of the molecular dipole moment, thus linking changes in chemical structure with device performance. Finally, white electroluminescence was demonstrated from single copolymers exhibiting broadened blue-green intramolecular charge transfer emission due to the interaction of fluorene (F) and dibenzothiophene-S,S-dioxide (S) units. Single layer and multilayer devices were optimised, and white emission with good spectral coverage and CIE coordinates of (0.35, 0.39) was achieved with the F/S copolymer. The emission colour varies significantly with emissive layer thickness and applied voltage. Addition of a thermally evaporated electron transport layer resulted in improvement in both device efficiency and colour stability

IMPOSING REGULARITY CONDITIONS ON A SYSTEM OF COST AND FACTOR SHARE EQUATIONS

Systems of equations comprising cost functions and first-order derivative equations are often used to estimate characteristics of production technologies. Unfortunately, many estimated systems violate the regularity conditions implied by economic theory. Sampling theory methods can be used to impose these conditions globally, but these methods destroy the flexibility properties of most functional forms. We demonstrate how Bayesian methods can be used to maintain flexibility by imposing regularity conditions locally. The Bayesian approach is used to estimate a system of cost and share equations for the merino-woolgrowing sector. The effect of local imposition of monotonicity and concavity on the signs and magnitudes of elasticities is examined.Cost functions, Markov Chain Monte Carlo, inequality constraints, Demand and Price Analysis,

Imposing regularity conditions on a system of cost and factor share equations

Systems of equations comprising cost functions and first‐order derivative equations are often used to estimate characteristics of production technologies. Unfortunately, many estimated systems violate the regularity conditions implied by economic theory. Sampling theory methods can be used to impose these conditions globally, but these methods destroy the flexibility properties of most functional forms. We demonstrate how Bayesian methods can be used to maintain flexibility by imposing regularity conditions locally. The Bayesian approach is used to estimate a system of cost and share equations for the merino wool‐growing sector. The effect of local imposition of monotonicity and concavity on the signs and magnitudes of elasticities is examined.Resource /Energy Economics and Policy,

Comparisons of landings to scientific advice indicate overshooting within the common TAC for skates and rays in the Northeast Atlantic

The International Council for the Exploration of the Sea (ICES) typically provides advice on fishing opportunities on a stock-by-stock basis. Nevertheless, levels of total allowable catch (TAC) are sometimes set for a collection of stocks and species (i.e. a common TAC). An explicit expectation of these is that landings will scale with ICES advice, especially when ICES advice is used to calculate the common TAC. This expectation is tested for skates and rays in the Northeast Atlantic, spanning 26 stocks, 8 species, and 3 ecoregions. Using ICES landings and ICES advice data from 2016 to 2022, we show that landings of several stocks and species have overshot their respective ICES advice, whereas others have undershot. Specifically, some stocks of blonde ray (Raja brachyura) in North Sea and Celtic Seas ecoregions are being landed at a rate that often exceeds double its ICES advice. By collating species based on their ICES assessment category and life-history traits, we find that those considered data-poor and potentially most vulnerable to fishing are consistently landed at higher-than-expected rates in the Celtic Seas. This study questions the appropriateness of a common TAC for skates and rays and calls for shifts towards the use of single-stock catch allocations and the application of advanced stock assessment methodologies

The effect of ageing on macrophage Toll-like receptor-mediated responses in the fight against pathogens

The cellular changes during ageing are incompletely understood yet immune system dysfunction is implicated in the age-related decline in health. The acquired immune system shows a functional decline in ability to respond to new pathogens whereas serum levels of cytokines are elevated with age. Despite these age-associated increases in circulating cytokines, the function of aged macrophages is decreased. Pathogen-associated molecular pattern receptors such as Toll-like receptors (TLRs) are vital in the response of macrophages to pathological stimuli. Here we review the evidence for defective TLR signalling in normal ageing. Gene transcription, protein expression and cell surface expression of members of the TLR family of receptors and co-effector molecules do not show a consistent age-dependent change across model systems. However, there is evidence for impaired downstream signalling events, including inhibition of positive and activation of negative modulators of TLR induced signalling events. In this paper we hypothesize that despite a poor inflammatory response via TLR activation, the ineffective clearance of pathogens by macrophages increases the duration of their activation and contributes to perpetuation of inflammatory responses and ageing

Evaluation of older people\u27s knowledge, awareness, motivation and perceptions about falls and falls prevention in residential aged care homes: A tale of two cities

Falls prevention strategies can only be effective in reducing falls amongst older people if they are adopted and enacted in their daily lives. There is limited evidence identifying what older people in residential aged care (RAC) homes understand about falls and falls prevention, or what may limit or enable their adoption of strategies. This study was conducted in two countries and explored older people’s knowledge and awareness of falls and their preferences, opportunities and motivation to undertake falls prevention strategies. A cross-sectional survey was administered to participants (N = 70) aged 65 years and over, living in six RAC homes in Perth, Australia and six RAC homes in Swansea, Wales, United Kingdom. Participants had limited knowledge about intrinsic falls risk factors and strategies to address these and frequently expressed self-blame regarding falling. Almost all (N = 67, 95.7%) participants felt highly motivated to maintain their current functional mobility and independence in everyday tasks. Key preferences for receiving falls prevention messages favoured a positive approach promoting wellness and independence (N = 41, 58.6%) via pictorial posters or brochures (N = 37, 52.9%) and small group discussions preferably with demonstrations (N = 18, 25.7%). Findings from this study may assist organisations and staff to more effectively engage with older people living in RAC about falls prevention and design targeted resources to address the motivations and preferences of this population

D10.3 - Report with an assessment of the WP results including ID10.7-ID10.11

Kew, C., & Griffiths, D. (2009). D10.3 - Report with an assessment of the WP results including ID10.7-ID10.11. TENCompetence.This report summarises Dissemination work carried out by the TENCompetence Project between months 30 and 42. It includes sections on workshops and events, standardisation of project outcomes, awareness raising and the TENCompetence Foundation, business models and interim sustainability plan.The work on this publication has been sponsored by the TENCompetence Integrated Project that is funded by the European Commission's 6th Framework Programme, priority IST/Technology Enhanced Learning. Contract 027087 [http://www.tencompetence.org