Agency Theory and Supply Chain Management: Goals and Incentives in Supply Chain Organisations

Purpose Agency theory (AT) offers opportunities to examine how the risk of opportunism can be prevented or minimised along supply chain organisations using incentives to achieve goal alignment. Methodology The study presents evidence of how members of such organisations achieve goal alignment through the use of incentives by empirically examining two complete supply chain organisations, including final customers, within the UK agri-food industry using a case study methodology. Findings The findings show that contractual goals can be divided into two different categories, shared supply chain organisational goals, and independent goals of each individual participant. In addition to monitoring ability, incentives can also be classified into short term financial and long term social incentives. Product attributes, in particular credence attributes, are also identified as having implications for both goals and incentives. Research limitations The supply chain perspective and case study methodology mean that the research findings cannot be generalised to other supply chains. A further limitation of the research is the use of different methods of data collection at the final customer point. Practical Implications Managers must ensure that appropriate incentives for all departments and individuals are designed to deliver the strategic goals of the supply chain organisation

Benign Paroxysmal Positional Vertigo (BPPV): History, Pathophysiology, Office Treatment and Future Directions

BPPV is the most common cause of vertigo. It most often occurs spontaneously in the 50 to 70 year age group. In younger individuals it is the commonest cause of vertigo following head injury. There is a wide spectrum of severity from inconsistent positional vertigo to continuous vertigo provoked by any head movement. It is likely to be a cause of falls and other morbidity in the elderly. Misdiagnosis can result in unnecessary tests. The cardinal features and a diagnostic test were clarified in 1952 by Dix and Hallpike. Subsequently, it has been established that the symptoms are attributable to detached otoconia in any of the semicircular canals. BPPV symptoms can resolve spontaneously but can last for days, weeks, months, and years. Unusual patterns of nystagmus and nonrepsonse to treatment may suggest central pathology. Diagnostic strategies and the simplest “office” treatment techniques are described. Future directions for research are discussed

A Balance Test for Chronic Perilymph Fistula

Perilymph fistula is defined as a leak of perilymph at the oval or round window. It excludes other conditions with “fistula” tests due to a dehiscent semicircular canal from cholesteotoma and the superior canal dehiscence syndrome. First recognized as a complication of stapedectomy, it then became apparent that head trauma and barotraumatic trauma from flying or diving could be a cause. Descriptions of “spontanenous” perilymph fistulas with no trauma history followed. It is likely that most perilymph fistula patients have a congential potential weakness of the otic capsule at the round or oval window. The vestibular symptoms have been assumed to be due to endolymphatic hydrops, but there is poor evidence. Their unilateral disequilibrium, nausea, and subtle cognitive problems suggest they are due to otolith disfunction and that these patients have a specific balance abnormality, unlike subjects with unilateral vestibular hypofuction. In this series of twenty patients with a confirmed fistula a logical simplification of Singleton's “eyes-closed turning” test predicted a PLF in twelve with a trauma history. In four no cause was found. In three a prior traumatic event was later recalled, but one patient had concealed it

Readout and Control Beyond a Few Qubits: Scaling-up Solid State Quantum Systems

Quantum entanglement and superposition, in addition to revealing interesting physics in their own right, can be harnessed as computational resources in a machine, enabling a range of algorithms for classically intractable problems. In recent years, experiments with small numbers of qubits have been demonstrated in a range of solid-state systems, but this is far from the numbers required to realise a useful quantum computer. In addition to the qubits themselves, quantum operation requires a host of classical electronics for control and readout, and current techniques used in few-qubit systems are not scalable. This thesis presents a series of techniques for control and readout of solid-state qubits, working towards scalability by integrating classical control with the quantum technology. Two techniques for reducing the footprint associated with readout of gallium arsenide spin qubits are demonstrated. Gate electrodes, used to define the quantum dot, are also shown to be sensitive state detectors. These gate-sensors, and the more conventional Quantum Point Contacts, are then multiplexed in the frequency domain, where three-channel qubit readout and ten-channel QPC readout are demonstrated. Two types of superconducting devices are also explored. The loss in superconducting coplanar waveguide resonators is measured, and a suppression of coupling to the parasitic electromagnetic environment is demonstrated. The thesis also details software for the simulation of Josephson-junction based circuits including features beyond what is available in commercial products. Finally, an architecture for managing control of a scalable machine is proposed where classical components are distributed throughout a cryostat and cryogenic switches route control pulses to the appropriate qubits. A simple implementation of the architecture is demonstrated that incorporates a double quantum dot, a gallium arsenide switch matrix, frequency multiplexed readout, and cryogenic classical computation

Tree-mediated methane emissions from tropical and temperate peatlands

Methane production and transport processes in peatlands are fairly well understood, but growing evidence for emission of methane through trees has highlighted the need to revisit methane transport processes. In wetland trees, morphological adaptations such as development of hypertrophied lenticels, aerenchyma and adventitious roots in response to soil anoxia mediates gas transport, transporting both oxygen from the atmosphere to oxygen-deprived roots and soil-produced methane from the root-zone to the atmosphere. Although, tree-mediated methane emissions from temperate tree species have been confirmed, methane emissions from tropical tree species and processes that control tree-mediated methane emissions remain unclear. This study explains the role of trees in transporting soil-produced methane to the atmosphere and uncovers the principal mechanisms of tree-mediated methane emissions. Methane emissions from eight tropical tree species and two temperate tree species were studied in situ. The mechanisms and controls on tree-mediated methane emissions were investigated using three year old common alder (Alnus glutinosa; 50 trees) grown under two artificially controlled water-table positions. Methane fluxes from whole mesocosms, the soil surface and tree stems were measured using static closed chambers. Both temperate and tropical tree species released significant quantities of methane, with tropical trees dominating ecosystem level methane fluxes. In temperate peatlands, both the methane gas transport mechanism and quantity of methane emitted from stems is tree-species dependent. In Alnus glutinosa, no correlations were observed between stomatal behaviour and tree-mediated methane emissions, however, stem methane emissions were positively correlated with both stem lenticel density and dissolved soil methane concentration. In Alnus glutinosa, no emissions were observed from leaf surfaces. The results demonstrate that exclusion of tree-mediated methane emissions from flux measurement campaigns in forested peatlands will lead to an underestimation of ecosystem-wide methane emissions

Reassessing the stable isotope composition assigned to methane flux from natural wetlands in isotope-constrained budgets

Stable isotope ratios in CH4 preserve information about its origin and history, and are commonly used to constrain global CH4 budgets. Wetlands are key contributors to the atmospheric burden of CH4 and typically are assigned a stable carbon isotope composition of ~-60 permil in isotope-weighted stable isotope models despite the considerable range of δ13C(CH4) values (~ -100 to -40 permil) known to occur in these diverse ecosystems. Kinetic isotope effects (KIEs) associated with the metabolism of CH4 -producing microorganisms generate much of the natural variation but highly negative and positive δ13C(CH4) values generally result from secondary processes (e.g., diffusive transport or oxidation by soil methanotrophs). Despite these complexities, consistent patterns exist in the isotope composition of wetland CH4 that can be linked conclusively to trophic status and consequently, natural succession or human perturbations that impact nutrient levels. Another challenge for accurate representation of wetlands in carbon cycle models is parameterisation of sporadic CH4 emission events. Abrupt release of large volumes of CH4 -rich bubbles in short periods of time can account for a significant proportion of the annual CH4 flux from a wetland but such events are difficult to detect using conventional methods. New infrared spectroscopy techniques capable of high temporal resolution measurements of CH4 concentration and stable isotope composition can readily quantify short-lived CH4 pulses. Moreover, the isotope data can be used conclusively to determine shifts in the mode of CH4 transport and provide the potential to link initiation of abrupt emission events to forcing by internal or external factors