Casimir effect from macroscopic quantum electrodynamics

The canonical quantization of macroscopic electromagnetism was recently presented in New J. Phys. 12 (2010) 123008. This theory is here used to derive the Casimir effect, by considering the special case of thermal and zero-point fields. The stress-energy-momentum tensor of the canonical theory follows from Noether's theorem, and its electromagnetic part in thermal equilibrium gives the Casimir energy density and stress tensor. The results hold for arbitrary inhomogeneous magnetodielectrics and are obtained from a rigorous quantization of electromagnetism in dispersive, dissipative media. Continuing doubts about the status of the standard Lifshitz theory as a proper quantum treatment of Casimir forces do not apply to the derivation given here. Moreover, the correct expressions for the Casimir energy density and stress tensor inside media follow automatically from the simple restriction to thermal equilibrium, without the need for complicated thermodynamical or mechanical arguments.Comment: Minor corrections. 21 pages. To appear in New J. Phy

Evaluation of the effects of space environment exposure on index of refraction and extinction coefficients of Apollo window materials

Temperature and radiation effects on index of refraction and extinction coefficients of Apollo window material

Canonical quantization of macroscopic electromagnetism

Application of the standard canonical quantization rules of quantum field theory to macroscopic electromagnetism has encountered obstacles due to material dispersion and absorption. This has led to a phenomenological approach to macroscopic quantum electrodynamics where no canonical formulation is attempted. In this paper macroscopic electromagnetism is canonically quantized. The results apply to any linear, inhomogeneous, magnetodielectric medium with dielectric functions that obey the Kramers-Kronig relations. The prescriptions of the phenomenological approach are derived from the canonical theory.Comment: 21 pages, additional reference

Damped vacuum states of light

We consider one-dimensional propagation of quantum light in the presence of a block of material, with a full account of dispersion and absorption. The electromagnetic zero-point energy for some frequencies is damped (suppressed) by the block below the free-space value, while for other frequencies it is increased. We also calculate the regularized (Casimir) zero-point energy at each frequency and find that it too is damped below the free-space value (zero) for some frequencies. The total Casimir energy is positive

Comment on "Quantum Friction - Fact or Fiction?"

If quantum friction existed [J.B. Pendry, New J. Phys. 12, 033028 (2010)] an unlimited amount of useful energy could be extracted from the quantum vacuum and Lifshitz theory would fail. Both are unlikely to be true.Comment: Comment on J.B. Pendry, New J. Phys. 12, 033028 (2010

Factors affecting linkage to care and engagement in care for newly diagnosed HIV-positive adolescents within fifteen adolescent medicine clinics in the United States

Early linkage to care and engagement in care are critical for initiation of medical interventions. However, over 50 % of newly diagnosed persons do not receive HIV-related care within 6 months of diagnosis. We evaluated a linkage to care and engagement in care initiative for HIV-positive adolescents in 15 U.S.-based clinics. Structural and client-level factors (e.g. demographic and behavioral characteristics, clinic staff and location) were evaluated as predictors of successful linkage and engagement. Within 32 months, 1,172/1,679 (69.8 %) of adolescents were linked to care of which 1,043/1,172 (89 %) were engaged in care. Only 62.1 % (1,043/1,679) of adolescents were linked and engaged in care. Linkage to care failure was attributed to adolescent, provider, and clinic-specific factors. Many adolescents provided incomplete data during the linkage process or failed to attend appointments, both associated with failure to linkage to care. Additional improvements in HIV care will require creative approaches to coordinated data sharing, as well as continued outreach services to support newly diagnosed adolescents

Canonical quantization of electromagnetism in spatially dispersive media

Copyright © 2014 IOP PublishingOpen Access JournalWe find the action that describes the electromagnetic field in a spatially dispersive, homogeneous medium. This theory is quantized and the Hamiltonian is diagonalized in terms of a continuum of normal modes. It is found that the introduction of nonlocal response in the medium automatically regulates some previously divergent results, and we calculate a finite value for the intensity of the electromagnetic field at a fixed frequency within a homogeneous medium. To conclude we discuss the potential importance of spatial dispersion in taming the divergences that arise in calculations of Casimir-type effects.EPSR

Horizon effects with surface waves on moving water

Surface waves on a stationary flow of water are considered, in a linear model that includes the surface tension of the fluid. The resulting gravity-capillary waves experience a rich array of horizon effects when propagating against the flow. In some cases three horizons (points where the group velocity of the wave reverses) exist for waves with a single laboratory frequency. Some of these effects are familiar in fluid mechanics under the name of wave blocking, but other aspects, in particular waves with negative co-moving frequency and the Hawking effect, were overlooked until surface waves were investigated as examples of analogue gravity [Sch\"utzhold R and Unruh W G 2002 Phys. Rev. D 66 044019]. A comprehensive presentation of the various horizon effects for gravity-capillary waves is given, with emphasis on the deep water/short wavelength case kh>>1 where many analytical results can be derived. A similarity of the state space of the waves to that of a thermodynamic system is pointed out.Comment: 30 pages, 15 figures. Minor change

Delivering UN Sustainable Development Goals’ Impact on Infrastructure Projects: An Empirical Study of Senior Executives in the UK Construction Sector

Achievement of the United Nations’ 2030 Sustainable Development Goals (SDG) is of paramount importance for both business and society. Across the construction sector, despite evidence that suggests 88% of those surveyed want to measure the SDG impact at both the business and project levels, there continues to be major challenge in achieving this objective. This paper shares the results of a qualitative research study of 40 interviews with executives from the United Kingdom (UK) construction industry. It was supported by a text-based content analysis to strengthen the findings. The results indicate that SDG measurement practices are embraced in principle but are problematic in practice and that rarely does action match rhetoric. While the research was completed in the UK, the findings have broader applicability to other countries since most construction firms have extensive global business footprints. Researchers can use the findings to extend the current understanding of measuring outcomes and impact at project level, and, for practitioners, the study provides insights into the contextual preconditions necessary to achieve the intended outcomes of adopting a mechanism for the measurement of SDGs. The international relevance of this research is inherently linked to the global nature of the SDGs and therefore the results could be used outside of UK

Redefining the Use of Sustainable Development Goals at the Organisation and Project Levels—A Survey of Engineers

The United Nations’ (UN) Sustainable Development Goals (SDGs) aim to deliver an improved future for people, planet and profit. However, they have not gained the required traction at the business and project levels. This article explores how engineers rate and use the SDGs at the organisational and project levels. It adopts the Realist Evaluation’s Context−Mechanism−Outcomes model to critically evaluate practitioners’ views on using SDGs to measure business and project success. The study addresses the thematic areas of sustainability and business models through the theoretical lens of Creating Shared Value and the Triple Bottom Line. A survey of 325 engineers indicated four primary shortfalls for measuring SDGs on infrastructure projects, namely (1) leadership, (2) tools and methods, (3) engineers’ business skills in measuring SDG impact and (4) how project success is too narrowly defined as outputs (such as time, cost and scope) and not outcomes (longer-term local impacts and stakeholder value). The research study is of value to researchers developing business models that address the SDGs and also practitioners in the construction industry who seek to link their investment decisions to the broader outcomes of people, planet and profit through the UN SDGs