Spontaneous decay rate and Casimir-Polder potential of an atom near a lithographed surface

Radiative corrections to an atom are calculated near a half-space that has arbitrarily-shaped small depositions upon its surface. The method is based on calculation of the classical Green's function of the macroscopic Maxwell equations near an arbitrarily perturbed half-space using a Born series expansion about the bare half-space Green's function. The formalism of macroscopic quantum electrodynamics is used to carry this over into the quantum picture. The broad utility of the calculated Green's function is demonstrated by using it to calculate two quantities --- the spontaneous decay rate of an atom near a sharp surface feature, and the Casimir-Polder potential of a finite grating deposited on a substrate. Qualitatively new behaviour is found in both cases, most notably in the latter where it is observed that the periodicity of the Casimir-Polder potential persists even outside the immediate vicinity of the grating.Comment: Title changed, typos correcte

Zeeman shift of an electron trapped near a surface

Boundary-dependent corrections to the spin energy eigenvalues of an electron in a weak magnetic field and confined by a harmonic trapping potential are investigated. The electromagnetic field is quantized through a normal-mode expansion obeying the Maxwell boundary conditions at the material surface. We couple the electron to this photon field and a classical magnetic field in the Dirac equation, to which we apply the unitary Foldy-Wouthuysen transformation in order to generate a nonrelativistic approximation of the Hamiltonian to the desired order. We obtain the Schrödinger eigenstates of an electron subject to double confinement by a harmonic potential and a classical magnetic field, and then use these within second-order perturbation theory to calculate the spin energy shift that is attributable to the surface-modified quantized field. We find that a pole at the eigenfrequency of a set of generalized Landau transitions gives dominant oscillatory contributions to the energy shift in the limit of tight harmonic confinement in a weak magnetic field, which also make the energy shift preferable to the magnetic moment for a physically meaningful interpretation

Intensity of Interaction in Suppy of Business Advice and Client Impact: A Comparison of Consultancy, Business Associations and Government Support Initiatives for SMEs

This paper assesses the supply of business advice using new empirical evidence from a large scale survey of SMEs. The chief focus of the paper is on a comparison of suppliers that operate in different environments of regulation, contract and reputation. The paper argues that interaction intensity varies with the level of information asymmetry of these different environments, between different types of service supplier and their clients. Interaction intensity between suppliers also varies as a result of the level of trust they enjoy: for example, the low trust enjoyed by consultants appears to encourage higher intensity of interaction which improves the tailoring of the service to the client's needs and enhances impact. The paper assesses interaction intensity using the existence of site visits and/or a written brief/contract as indicators. Although these measures have limitations, the paper demonstrates clear and significant differences between suppliers in terms of interaction intensity, use of contracts and impact in three broad categories: private sector consultancy (low trust, high intensity, high impact), business associations (high trust, low intensity, moderate impact) and government support agencies (moderate trust, moderate to high intensity, moderate or low impact). Multivariate estimation methods demonstrate that significant differences in interaction intensity, use of contracts and impact by client type are much less important than differences in supplier type. This indicates that suppliers generally develop more into niche service fields or groups of services rather than niches related to types of firm.Business Services, Contracts, Business Link, Trust, Reputation

The Use and Impact of Business Advice by SMEs in Britain: An Empirical Assessment Using Logit and Ordered Logit Models

This paper assesses the effect of differences in types of client on the use and impact of business advice by SMEs in Britain using new survey evidence from the Cambridge ESRC Centre for Business Research Survey of 1997. The survey, covering over 2500 respondents, is the largest and most definitive assessment available in Britain. Moreover, the survey allows an assessment of the full range of the providers of external advice, the private sector, business associations and various public sector bodies, as well as the fields of advice. Using multivariate logit models we find that size of firm, rate of growth and innovation appear to be the main variables influencing the likelihood of firms seeking external advice, both from different sources and from different fields. Other variables which are investigated include, age, profitability, skill levels, manufacturer/services, and exporter/non-exporter. Ordered logit models of the impact of the advice demonstrate that there are significant differences between clients' perceived impact of advice and the sources of advice they use, chiefly as a result of firm size, and to a lesser extent for growth, innovation and export levels.Business Advice, Business Link, consultancy, logit, ordered logit

Knowledge Transfer Needs and Methods

INE/AUTC 12.3

Willingness to pay for recycling food waste in the Brisbane Region

Kerbside recycling in Australia has focused on paper, cardboard, plastics and bottles and in some areas green waste. Another area for potential kerbside recycling is organic waste. This study uses a dichotomous choice contingent valuation format with follow-up open-ended willingness to pay question to estimate the household willingness to pay for the introduction of a kerbside recycling scheme for kitchen waste. Two provision rules were used. The first sample split contained a majority decision rule while the second sample split contained a provision rule where participation is voluntary. Households across the Brisbane statistical sub-division currently pay in the order of $250 per annum for their kerbside waste collection scheme. This study indicates that on average Brisbane households would be WTP an additional$32 to $35 per year for a general waste bin where food waste is split from general waste. There was no significant difference in results between sample splits with majority or voluntary provision rules. Whether the provision of a food waste recycling scheme is economically efficient requires a consideration of all the potential costs and benefits. Other relevant costs and benefits for inclusion in a benefit cost analysis would include those associated with bin replacement, any additional collection and transport costs, composting costs, revenues from compost sales and avoided landfill costs. If a compulsory food waste recycling scheme could be provided to all households for less than$32 to $35 per household per annum then the benefits of the scheme would exceed the costs and would be considered to be economically efficient and desirable from a community welfare perspective. Given the difficulties of estimating precise WTP values from dichotomous choice data, any BCA of a compulsory scheme incorporating the results of this study should undertake sensitivity testing that includes the range of values reported including dichotomous choice and open-ended means to determine the robustness of BCA results to variations in the welfare estimate. Notwithstanding, the results of any BCA, decision-makers also need to be cognisant of the high proportion of respondents who did not support a kerbside food waste recycling scheme. The data from the study could also be used to undertake a BCA of a voluntary scheme.Environmental Economics and Policy,

Analysing options for the Red Gum Forests along the Murray River

The Victorian Environmental Assessment Council is conducting an investigation into the management of the public land River Red Gum Forests of the Murray River Valley in Victoria. In this paper the authors apply the results of an earlier Choice Modelling exercise commissioned by VEAC to estimate the non-use values of the forests. A Benefit Cost Analysis of VEAC's draft recommendations included assessment of the market and non market values associated with different River Red Gum forest management strategies. It is concluded that the use of water for environmental flows is competitive with its use for irrigation. Other economic values associated with timber harvesting, grazing and duck hunting are small in comparison with the water values.Choice Modelling, Environment, River Red Gums, Benefit Cost Analysis, Water Resources, Land Economics/Use, Resource /Energy Economics and Policy,

Willingness to pay for kerbside recycling the Brisbane Region

Waste policy in Australia has a strong focus on kerbside recycling. This has a range of costs and benefits to the community, including non-market benefits. However, in Australia, there has been little investigation of household willingness to pay for kerbside recycling. This paper used mixed logit choice modelling to estimate the willingness to pay of households in Brisbane, Australia for kerbside waste collection services including kerbside recycling. It was found that households in Brisbane have a positive and significant willingness to pay of $131.49 per annum for fortnightly kerbside recycling and would be willing to pay an additional$18.30 to increase the frequency of this service to weekly. The utility of respondents was, however, found to decline by $34.18 per year if general waste collection increased from weekly to twice a week. Based on the assumptions used in this study it would appear that the willingness to pay for kerbside recycling exceeds the net financial costs of this service, suggesting that the scheme is economically efficient. However, the reported economic values for recycling may overstate the community’s true willingness to pay if household responses to the choice questions were confounded by their underlying perceptions about the environmental and resource sustainability benefits of recycling.Environmental Economics and Policy, Research Methods/ Statistical Methods,

The Casimir-Polder potential in the presence of a Fock state

Atom-surface forces using excited states have a host of compelling applications, including repulsive and lateral forces. However, such states can be fragile and difficult to prepare. Here we report an explicit normal-mode based calculation of the Casimir-Polder potential between a ground-state atom and a non-dispersive surface in the presence of an external quantised field. The potential we derive shares some features with that of excited-state Casimir-Polder forces even though we consider a ground-state atom. Our work provides a physically transparent and intuitive picture of driven Casimir-Polder potentials, as well as expanding on previous investigations by providing analytic results that fully include retardation, as well as being applicable for any choice of mutual alignment of the atom's dipole moment, the external field, and the surface normal

Manipulating the Coulomb interaction: A Green's function perspective

We present a unified framework for studying Coulomb interactions in arbitrary environments using macroscopic quantum electrodynamics on the basis of the electromagnetic Green's function. Our theory can be used to derive the Coulomb potential of a single charged particle as well as that between two charges in the presence of media, bodies and interfaces of arbitrary shapes. To demonstrate this, we reproduce the well-known screened Coulomb force, account for local-field effects and consider new cases such as a dielectric cavity and a conducting plate with a hole