A monopole antenna at optical frequencies: single-molecule near-field measurements

We present a monopole antenna for optical frequencies (~600 THz) and discuss near-field measurements with single fluorescent molecules as a technique to characterize such antennas. The similarities and differences between near-field antenna measurements at optical and radio frequencies are discussed in detail. Two typical antenna properties, polarization selectivity and resonances, are studied for the optical monopole by direct near-field measurements and finite integration technique calculations. The antenna is driven by the local field of a sub-wavelength aperture. This gives rise to a dependence of the antenna response on the orientation of the local field vector, in an analogous way to the polarization selectivity of linear wire antennas. The antenna resonances are studied by varying the antenna length. Typical monopole resonances are demonstrated. The finite conductivity of metals at optical frequencies (in combination with the antenna radius) causes the wavelength of the surface charge density oscillation (surface plasmon polariton) along the antenna to be shortened in comparison to the free space wavelength. As a result, resonances for the optical monopole antenna occur at much shorter relative lengths than for conventional radio monopole antennas\ud \u

Defining and evaluating stability in early years assessment

Stability is an important underlying assumption in any form of assessment-supported decision-making. Since early years development is frequently described as unstable, the concept plays a central role in the discussion surrounding early years assessment. This paper describes stability as a set of assumptions about the way individual scores change over time. Here, an analytical framework developed by Tisak and Meredith (1990), which can be used to evaluate these assumptions, is extended and applied to evaluate the stability of mathematics scores of 1402 children between kindergarten and third grade. Multilevel models are used to evaluate the assumption that each child has a unique individual growth rate, as well as the assumption that the ranking of children’s test scores is consistent over time. The results show that for a large proportion of the children, assuming unique individual growth rates leads to similar predictions as assuming that children develop at an equal pace. While individual differences in growth rate may provide relevant information, these differences only become apparent after several test administrations. As such, decisions should not be based on perceived stagnated or accelerated growth over a short period

Flying with doctors: Experiences with the application of 6 techniques from aviation industry in the Rotterdam Eye Hospital

Intoduction. Aviation industry is often put forward as an example in creating safer health care. Comparing aviation and health care, there are similarities in using technology, working with highly specialized professional teams and the need for dealing with risk and uncertainties (Sexton 2000; Powell 2006; Kao & Thomas 2008). Rhetorical use of the resemblance however, does not directly contribute to the safety of the health care system. To measure the added value of the experiences in aviation for the health care sector, it is preferable to study in detail the use of aviation based principals in daily practice

A systematic review of measurement uncertainty visualizations in the context of standardized assessments

This systematic review summarized findings of 29 studies evaluating visual presentation formats appropriate for communicating measurement uncertainty associated with standardized clinical assessment instruments. Studies were identified through systematic searches of multiple databases (Medline, Embase, PsycInfo, ERIC, Scopus, and Web of Science). Strikingly, we found no studies which were conducted using samples of clinicians and included clinical decision-making scenarios. Included studies did however find that providing participants with information about measurement uncertainty may increase awareness of uncertainty and promote more optimal decision making. Formats which visualize the shape of the underlying probability distribution were found to promote more accurate probability estimation and appropriate interpretations of the underlying probability distribution shape. However, participants in the included studies did not seem to benefit from the additional information provided by such plots during decision-making tasks. Further explorations into how presentations of measurement uncertainty impact clinical decision making are needed to examine whether findings of the included studies generalize to clinician populations. This review provides an important overview of pitfalls associated with formats commonly used to communicate measurement uncertainty in clinical assessment instruments, and a potential starting point for further explorations into promising alternatives. Finally, our review offers specific recommendations on how remaining research questions might be addressed.</p

Preschool/Kindergarten teachers' conceptions of standardised testing

Standardised tests play an important role in early childhood (EC) education in many countries. Although teachers' conceptions largely determine whether and how these instruments are used, research on this topic is scarce. As a result, factors that influence conceptions of standardised testing have remained largely unexplored. To examine teachers' conceptions of standardised testing and aspects that may influence these conceptions, Brown's CoA-III-A questionnaire was distributed to 97 EC educators. Based on their responses, a selection of six preschool/kindergarten teachers participated in a series of semi-structured interviews. Analyses of the questionnaire and the interviews indicated that the teachers did not see these tests solely as instruments for accountability or improvement. While some perceived the test as pleasant confirmation, others perceived the results as negative opposition to their own observations. The teachers' conceptions were influenced by classroom population, management team, and the ascribed purpose of the test