Conformal carpet and grating cloaks

We introduce a class of conformal versions of the previously introduced quasi-conformal carpet cloak, and show how to construct such conformal cloaks for different cloak shapes. Our method provides exact refractive-index profiles in closed mathematical form for the usual carpet cloak as well as for other shapes. By analyzing their asymptotic behavior, we find that the performance of finite-size cloaks becomes much better for metal shapes with zero average value, e.g., for gratings.Comment: added Ref. 12; added 2 figures; reformatte

Rotor dynamic behaviour of a high-speed oil-free motor compressor with a rigid coupling supported on four radial magnetic bearings

The combination of a high-speed motor, dry gas seals, and magnetic bearings realized in this unit facilitates the elimination of oil. The motor is coupled with a quill shaft to the compressor. This yields higher natural frequencies of the rotor than with the use of a diaphragm coupling and helps to maintain a sufficient margin of the maximum speed to the frequency of the second compressor bending mode. However, the controller of each bearing then has to take the combined modes of both machines into account. The requirements for the controller to ensure stability and sufficient damping of all critical speeds are designed and compared with the implemented controller. The calculated closed loop behavior was confirmed experimentally, except the stability of some higher modes due to slight frequency deviations of the rotor model to the actual rotor. The influence of a mechanical damper as a device to provide additional damping to high models is demonstrated theoretically. After all, it was not necessary to install the damper, since all modes cold be stabilized by the controller

Electrostatics of Gapped and Finite Surface Electrodes

We present approximate methods for calculating the three-dimensional electric potentials of finite surface electrodes including gaps between electrodes, and estimate the effects of finite electrode thickness and an underlying dielectric substrate. As an example we optimize a radio-frequency surface-electrode ring ion trap, and find that each of these factors reduces the trapping secular frequencies by less than 5% in realistic situations. This small magnitude validates the usual assumption of neglecting the influences of gaps between electrodes and finite electrode extent.Comment: 9 pages, 9 figures (minor changes

Modified spin-wave theory with ordering vector optimization I: frustrated bosons on the spatially anisotropic triangular lattice

We investigate a system of frustrated hardcore bosons, modeled by an XY antiferromagnet on the spatially anisotropic triangular lattice, using Takahashi's modified spin-wave (MSW) theory. In particular we implement ordering vector optimization on the ordered reference state of MSW theory, which leads to significant improvement of the theory and accounts for quantum corrections to the classically ordered state. The MSW results at zero temperature compare favorably to exact diagonalization (ED) and projected entangled-pair state (PEPS) calculations. The resulting zero-temperature phase diagram includes a 1D quasi-ordered phase, a 2D Neel ordered phase, and a 2D spiraling ordered phase. We have strong indications that the various ordered or quasi-ordered phases are separated by spin-liquid phases with short-range correlations, in analogy to what has been predicted for the Heisenberg model on the same lattice. Within MSW theory we also explore the finite-temperature phase diagram. We find that the zero-temperature long-range-ordered phases turn into quasi-ordered phases (up to a Berezinskii-Kosterlitz-Thouless temperature), while zero-temperature quasi-ordered phases become short-range correlated at finite temperature. These results show that modified spin-wave theory is very well suited for describing ordered and quasi-ordered phases of frustrated XY spins (or, equivalently, of frustrated lattice bosons) both at zero and finite temperatures. While MSW theory, just as other theoretical methods, cannot describe spin-liquid phases, its breakdown provides a fast method for singling out Hamiltonians which may feature these intriguing quantum phases. We thus suggest a tool for guiding our search for interesting systems whose properties are necessarily studied with a physical quantum simulator.Comment: 40 pages, 16 figure

Women's perceptions and experiences of breastfeeding support: A metasynthesis

Background: Both peer and professional support have been identified as important to the success of breastfeeding. The aim of this metasynthesis was to examine women’s perceptions and experiences of breastfeeding support, either professional or peer, in order to illuminate the components of support that they deem ‘supportive’. Methods: The metasynthesis included studies of both formal or ‘created’ peer and professional support for breastfeeding women but excluded studies of family or informal support. Qualitative studies were included as well as large scale surveys if they reported the analysis of qualitative data gathered through open ended responses. Primiparous and multiparous women who initiated breastfeeding were included. Only studies published in English, in peer reviewed journals and undertaken between 1990 and December 2007 were included. After assessment for relevance and quality, 31 studies were included in the metasynthesis. Meta-ethnographic methods were used to identify categories and themes. Results: The metasynthesis resulted in four categories comprising a total of 20 themes. The synthesis indicates that support for breastfeeding occurs along a continuum from authentic presence at one end, perceived as effective support, to disconnected encounters at the other, perceived as ineffective or even discouraging and counterproductive. Second, the synthesis identified a facilitative approach, versus a reductionist approach as contrasting styles of support women experienced as helpful or unhelpful. Conclusions: The findings of this metasynthesis emphasise the importance of person-centred communication skills and of relationships in supporting a woman to breastfeed. Organisational systems and services that facilitate continuity of care/r, for example continuity of midwifery care or peer support models, are more likely to facilitate an authentic presence

Australian parents’ use of universal child and family health services: A consumer survey

© 2018 John Wiley & Sons Ltd This study aimed to explore Australian parents’ use of universally available well-child health services. It used an online survey of 719 parents of children aged from birth to 5 years in all states and territories to examine patterns of service use and consumer preferences. In Australia, several health professional groups provide advice to pregnant women, infants, children, and parents, offering health promotion, developmental screening, parenting support, and referral to specialist health services if required. The survey examined parents’ use of different child and family health providers, and their preferences for support with several common parenting issues. The study indicated that families with young children obtain primary healthcare from a range of service providers, often more than one, depending on children's ages and needs. Parents frequently visit general practitioners for immunisation and medical concerns. They attend dedicated child and family health nurses for parenting advice and well-child checks and prefer them as an information source for many health issues. However, a substantial proportion of parents (44.1%) do not currently visit a child and family health nurse, often because they not only do not perceive a need but also sometimes because these services are unknown, inaccessible, or considered unsuitable. They may seek advice from less qualified sources. There is potential for increased collaboration between child and family health providers to ensure effective resource use and consistency of parenting information and advice. Nursing services may need to address accessibility and appropriateness of care

‘Being the bridge and the beacon’: a qualitative study of the characteristics and functions of the liaison role in child and family health services in Australia

© 2016 John Wiley & Sons Ltd Aims and objectives: This article explores the characteristics and functions of the liaison role in child and family health services in Australia. Background: Liaison roles are increasingly being used to improve communication between health services and professionals and to facilitate access to support for individuals and families in need. Nurses are commonly, although not always, the professionals who undertake these roles. Research on the role and outcomes of liaison positions in child and family health services is limited in Australia and internationally. Design: A qualitative interpretive design informed this study. Interviews and focus groups were conducted with 40 liaison and other health professionals, primarily nurses, working with families with newborn and young children in two Australian States. Data were analysed thematically. Results: Three major themes were identified reflecting the importance of defining the role and tasks which included building bridges between services and professionals, supporting families during transition between services and supporting clinicians. Several facilitators and barriers were identified, including concerns about sustainability of the roles. Conclusions: Professionals working in a liaison role in child and family health services emphasise that these positions have the potential to link services and professionals, thereby providing more effective care pathways for children and families especially for those with complex and multiple vulnerabilities. While a few children and family health services in Australia provide liaison services, the extent of liaison support and the outcomes for families in Australia is unknown. Relevance to clinical practice: Nurses working with children and families are the most likely health professionals to undertake a liaison role. In many nursing contexts, liaison roles are relatively new and those in the role have the responsibility to define the key purpose of their role. Liaison roles are multifaceted requiring the nurse to have excellent communication and negotiation skills to effectively link diverse professionals and services, while simultaneously engaging with and supporting vulnerable families and children. Nurses in these roles also support and educate clinical colleagues