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

TeenTech: getting young people engaged with information literacy

Rebecca Jones, Maggie Philbin and Jane Secker talk about TeenTech’s Research and Information Literacy Award, sponsored by ILG, which aims to show how information literacy underpins the acquisition of digital skills

Trends in Ages at Key Reproductive Transitions in the United States, 1951–2010

AbstractBackgroundKey sexual and reproductive health milestones typically mark changing life stages with different fertility intentions and family planning needs. Knowing the typical ages at such events contributes to our understanding of changes in family formation and transition to adulthood and helps inform needs for reproductive health services.MethodsWe used data from the 1982–2010 National Surveys of Family Growth and the 1995 National Survey of Adolescent Males and event history methods to examine trends over time for women and men in the median ages at several reproductive and demographic events.FindingsWomen's reports indicate that age at menarche has changed little since 1951. Women's and men's median ages at first sex declined through the 1978 birth cohort, but increased slightly since then, to 17.8 years for women and 18.1 for men. The interval from first sex to first contraceptive use has narrowed, although Hispanic women have a longer interval. Age at first union (defined as the earlier of first marriage or first cohabiting relationship) has remained relatively stable, but the time between median age at first sex and median age at first birth has increased to 9.2 years for women and 11.4 for men. For some women and men born in the late 1970s, median age at first birth was earlier than median age at first marriage for the first time in at least the past several decades.ConclusionThe large majority of the reproductive years are spent sexually active. Thus, women have a lengthy period during which they require effective methods. In particular, the period between first sex and first childbearing has lengthened, but long-acting method use, although increasing, has not kept up with this shift. Moving the contraceptive method mix toward underutilized but highly effective contraceptive methods has the potential to reduce the unintended pregnancy rate

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

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

A new perspective to evaluate the antecedent path of adoption of digital technologies in major projects of construction industry: A case study in China

The adoption of digital technologies is key to the digital transformation of the construction industry. However, the current adoption of digital technologies is limited. This study uses China as a case, combines the DOI and TOE theories to identify impact factors of the adoption of digital technologies in major projects. The configuration analysis is complemented with fuzzy-set qualitative comparative analysis. As a result, the study constructs the “TOE-D Technology Adoption Antecedent Framework”, including 11 antecedents, and identifies three distinct configurations types, namely: “Needs-Resource-Collaboration”; “Resource” under high competitive pressure; and “Resource” under low competitive pressure. Comparing the configurations horizontally, the core or edge characteristics of factor in configurations are analyzed. The results can help major projects in the construction industry to ascertain a combination of elements, which promote the adoption of digital technologies so that project practitioners can make targeted and precise adjustments to enable digital transformation of the construction industry

Industry 4.0 Technological Advancement in the Food and Beverage Manufacturing Industry in South Africa—Bibliometric Analysis via Natural Language Processing

The food and beverage (FOODBEV) manufacturing industry is a significant contributor to global economic development, but it is also subject to major global competition. Manufacturing technology evolution is rapid and, with the Fourth Industrial Revolution (4IR), ever accelerating. Thus, the ability of companies to review and identify appropriate, beneficial technologies and forecast the skills required is a challenge. 4IR technologies, as a collection of tools to assist technological advancement in the manufacturing sector, are essential. The vast and diverse global technology knowledge base, together with the complexities associated with screening in technologies and the lack of appropriate enablement skills, makes technology selection and implementation a challenge. This challenge is premised on the knowledge that there are vast amounts of information available on various research databases and web search engines; however, the extraction of specific and relevant information is time-intensive. Whilst existing techniques such as conventional bibliometric analysis are available, there is a need for dynamic approaches that optimise the ability to acquire the relevant information or knowledge within a short period with minimum effort. This research study adopts smart knowledge management together with artificial intelligence (AI) for knowledge extraction, classification, and adoption. This research defines 18 FOODBEV manufacturing processes and adopts a two-tier Natural Language Processing (NLP) protocol to identify technological substitution for process optimisation and the associated skills required in the FOODBEV manufacturing sector in South Africa

Do Students with Disabilities Successfully Transition into the Work Force or Postsecondary Education?

This research focuses on students with disabilities and their transition and career planning for postsecondary life. The United States federal government has put into law, regulations and guidelines for children with disabilities. The Individuals with Disabilities Act (IDEA) requires states and school districts to have a transition plan in place for all students with disabilities. The transition plan should prepare students for further education, employment, and independent living. Transition plans need to take into account the individual student’s interest and abilities. Educators are in agreement that children with disabilities need to have a transition plan. Educators often have different ideas on what should be included in a transition plan. Several educators believe their school district can improve on their transition and career plans

Perfect imaging with positive refraction in three dimensions

Maxwell's fish eye has been known to be a perfect lens within the validity range of ray optics since 1854. Solving Maxwell's equations we show that the fish-eye lens in three dimensions has unlimited resolution for electromagnetic waves

Environmental Regulation and Green Productivity of the Construction Industry in China

There are few studies analyzing whether different types of environmental regulation have differential impacts on the efficiency of the construction industry. Using 2012-2016 panel data from 30 provinces in China, the green total factor productivity (GTFP) of the construction industry is measured with a global Malmquist Luenberger productivity index based on the epsilon measure (EBM-GML) model. Thereafter, a panel Tobit regression model is proposed to explore the relationship between three types of environmental regulation and the GTFP of the construction industry. The results show that: (1) from 2012 to 2016, the GTFP of the Chinese construction industry grew slowly at an average annual rate of 0.14%; (2) both one-phase lagged command-and-control and current phase market-based environmental regulation had a positive linear relationship with GTFP. One-phase lagged voluntary environmental regulation on the other hand, had an inverted U-shaped relationship with GTFP; (3) the three types of environmental regulation can be combined to establish a suitable environmental regulation system. The findings of this study provide guidance for the sustainable development of the construction industry by combining the actions of different types of environmental regulation