Exceptional points of degeneracy and branch points for coupled transmission lines - Linear-algebra and bifurcation theory perspectives

We provide a new angle to investigate exceptional points of degeneracy (EPD) relating the current linear-algebra point of view to bifurcation theory. We apply these concepts to EPDs related to propagation in waveguides supporting two modes (in each direction), described as a coupled transmission line. We show that EPDs are singular points of the dispersion function associated with the fold bifurcation connecting multiple branches of dispersion spectra. This provides an important connection between various modal interaction phenomena known in guided-wave structures with recent interesting effects observed in quantum mechanics, photonics, and metamaterials systems described in terms of the algebraic EPD formalism. Since bifurcation theory involves only eigenvalues, we also establish the connection to the linear-algebra point of view by casting the system eigenvectors in terms of eigenvalues, analytically showing that the coalescence of two eigenvalues results automatically in the coalescence of the two respective eigenvectors. Therefore, for the studied two-coupled transmission-line problem, the eigenvalue degeneracy explicitly implies an EPD. Furthermore, we discuss in some detail the fact that EPDs define branch points in the complex frequency plane, we provide simple formulas for these points, and we show that parity-time (PT) symmetry leads to real-valued EPDs occurring on the real-frequency axis

Improving public services through open data: public toilets

Bichard’s work for the TACT3 project (Bichard REF Output 3) found that UK toilet provision is not centrally collated and no national map or database of toilets exists. In contrast, the UK government’s white paper Open Public Services (2011) emphasised its commitment to incorporating the use of Open Data in public services provision that could be tailored to community preferences, and therefore be more sustainable. Incorporating Open Data on public toilet provision, Bichard and Knight (RCA) developed The Great British Public Toilet Map (GBPTM). Whilst a number of other websites and applications map toilets by ‘crowd surfing’, GBPTM is entirely populated by Open Data, and not only uses the data as information for users, but informs members of the public that such information is available and accessible for their use. This paper presents the development of the GBPTM, including inclusive design research and studies that compare accuracy of information directly provided by users with Open Data collected by local authorities. It suggests that, to meet the health and well-being of an ageing population, a sustainable and cost-effective solution must be found for ‘publicly accessible’ toilet provision, including opening up provision beyond that ‘for customers only’ and providing accurate information on current public provision. The paper highlights the barriers encountered in the production of Open Data by local authorities. A review of the paper in the journal Civil Engineering (May 2013) described the design of the GBPTM as a ‘simple and elegant solution’. The development of a digital output and an understanding of digitally based research led to Bichard’s successful submission to an EPSRC Digital Economy sandpit, in which she developed an interdisciplinary project with the Universities of Newcastle, Bournemouth and the West of England. The project, Family Rituals 2.0, secured £750,000 in research funding with Bichard as co-investigator (2013–15)

Survey of the needs of patients with spinal cord injury: impact and priority for improvement in hand function in tetraplegics\ud

Objective: To investigate the impact of upper extremity deficit in subjects with tetraplegia.\ud \ud Setting: The United Kingdom and The Netherlands.\ud \ud Study design: Survey among the members of the Dutch and UK Spinal Cord Injury (SCI) Associations.\ud \ud Main outcome parameter: Indication of expected improvement in quality of life (QOL) on a 5-point scale in relation to improvement in hand function and seven other SCI-related impairments.\ud \ud Results: In all, 565 subjects with tetraplegia returned the questionnaire (overall response of 42%). Results in the Dutch and the UK group were comparable. A total of 77% of the tetraplegics expected an important or very important improvement in QOL if their hand function improved. This is comparable to their expectations with regard to improvement in bladder and bowel function. All other items were scored lower.\ud \ud Conclusion: This is the first study in which the impact of upper extremity impairment has been assessed in a large sample of tetraplegic subjects and compared to other SCI-related impairments that have a major impact on the life of subjects with SCI. The present study indicates a high impact as well as a high priority for improvement in hand function in tetraplegics.\ud \u

Real-space mapping of tailored sheet and edge plasmons in graphene nanoresonators

Plasmons in graphene nanoresonators have many potential applications in photonics and optoelectronics, including room-temperature infrared and terahertz photodetectors, sensors, reflect arrays or modulators1, 2, 3, 4, 5, 6, 7. The development of efficient devices will critically depend on precise knowledge and control of the plasmonic modes. Here, we use near-field microscopy8, 9, 10, 11 between λ0 = 10–12 μm to excite and image plasmons in tailored disk and rectangular graphene nanoresonators, and observe a rich variety of coexisting Fabry–Perot modes. Disentangling them by a theoretical analysis allows the identification of sheet and edge plasmons, the latter exhibiting mode volumes as small as 10−8λ03. By measuring the dispersion of the edge plasmons we corroborate their superior confinement compared with sheet plasmons, which among others could be applied for efficient 1D coupling of quantum emitters12. Our understanding of graphene plasmon images is a key to unprecedented in-depth analysis and verification of plasmonic functionalities in future flatland technologies.Peer ReviewedPostprint (author's final draft

Pay for Performance: A Reflection on How a Global Perspective Could Enhance Policy and Research

Pay-for-performance (P4P) is the provision of financial incentives to healthcare providers based on pre-specified performance targets. P4P has been used as a policy tool to improve healthcare provision globally. However, researchers tend to cluster into those working on high or low- and middle-income countries (LMICs), with still limited knowledge exchange, potentially constraining opportunities for learning from across income settings. We reflect here on some commonalities and differences in the design of P4P schemes, research questions, methods and data across income settings. We highlight how a global perspective on knowledge synthesis could lead to innovations and further knowledge advancement

Illegal immigration and media exposure: evidence on individual attitudes

Illegal immigration has been the focus of much debate in receiving countries, but little is known about the drivers of individual attitudes towards illegal immigrants. To study this question, we use the CCES survey, which was carried out in 2006 in the USA. We find evidence that—in addition to standard labor market and welfare state considerations—media exposure is significantly correlated with public opinion on illegal immigration. Controlling for education, income, ideology, and other socio-demographic characteristics, individuals watching Fox News are 9 percentage points more likely than CBS viewers to oppose the legalization of undocumented immigrants. We find an effect of the same size and direction for CNN viewers, whereas individuals watching PBS are instead more likely to support legalization. Ideological self-selection into different news programs plays an important role, but cannot entirely explain the correlation between media exposure and attitudes about illegal immigration

The RR Lyrae Distance Scale

We review seven methods of measuring the absolute magnitude M_V of RR Lyrae stars in light of the Hipparcos mission and other recent developments. We focus on identifying possible systematic errors and rank the methods by relative immunity to such errors. For the three most robust methods, statistical parallax, trigonometric parallax, and cluster kinematics, we find M_V (at [Fe/H] = -1.6) of 0.77 +/- 0.13, 0.71 +/- 0.15, 0.67 +/- 0.10. These methods cluster consistently around 0.71 +/- 0.07. We find that Baade-Wesselink and theoretical models both yield a broad range of possible values (0.45-0.70 and 0.45-0.65) due to systematic uncertainties in the temperature scale and input physics. Main-sequence fitting gives a much brighter M_V = 0.45 +/- 0.04 but this may be due to a difference in the metallicity scales of the cluster giants and the calibrating subdwarfs. White-dwarf cooling-sequence fitting gives 0.67 +/- 0.13 and is potentially very robust, but at present is too new to be fully tested for systematics. If the three most robust methods are combined with Walker's mean measurement for 6 LMC clusters, V_{0,LMC} = 18.98 +/- 0.03 at [Fe/H] = -1.9, then mu_{LMC} = 18.33 +/- 0.08.Comment: Invited review article to appear in: `Post-Hipparcos Cosmic Candles', A. Heck & F. Caputo (Eds), Kluwer Academic Publ., Dordrecht, in press. 21 pages including 1 table; uses Kluwer's crckapb.sty LaTeX style file, enclose

The breadth of primary care: a systematic literature review of its core dimensions

Background: Even though there is general agreement that primary care is the linchpin of effective health care delivery, to date no efforts have been made to systematically review the scientific evidence supporting this supposition. The aim of this study was to examine the breadth of primary care by identifying its core dimensions and to assess the evidence for their interrelations and their relevance to outcomes at (primary) health system level. Methods: A systematic review of the primary care literature was carried out, restricted to English language journals reporting original research or systematic reviews. Studies published between 2003 and July 2008 were searched in MEDLINE, Embase, Cochrane Library, CINAHL, King's Fund Database, IDEAS Database, and EconLit. Results: Eighty-five studies were identified. This review was able to provide insight in the complexity of primary care as a multidimensional system, by identifying ten core dimensions that constitute a primary care system. The structure of a primary care system consists of three dimensions: 1. governance; 2. economic conditions; and 3. workforce development. The primary care process is determined by four dimensions: 4. access; 5. continuity of care; 6. coordination of care; and 7. comprehensiveness of care. The outcome of a primary care system includes three dimensions: 8. quality of care; 9. efficiency care; and 10. equity in health. There is a considerable evidence base showing that primary care contributes through its dimensions to overall health system performance and health. Conclusions: A primary care system can be defined and approached as a multidimensional system contributing to overall health system performance and health

Mosquito nets in a rural area of Western Kenya: ownership, use and quality

<p>Abstract</p> <p>Background</p> <p>Insecticide-treated nets (ITNs) are regarded as one of the most effective strategies to prevent malaria in Africa. This study analyses the use and quality of nets owned by households in an area of high net coverage.</p> <p>Methods</p> <p>A structured questionnaire on ownership and use of nets was administered to the households of individuals sampled from a local health centre in south Kisii district, Kenya. A physical inspection of all the nets in the households was done and their conditions recorded on spot check forms designed for that purpose.</p> <p>Results</p> <p>Of the 670 households surveyed, 95% owned at least one net. Only 59% of household residents slept under a net during the night prior to the survey. 77% of those who slept under a net used an insecticide-treated net (ITN) or long-lasting insecticide-treated nets (LLIN). Out of 1,627 nets in the survey households, 40% were deemed to be of poor quality because of holes. Compared to other age groups, children aged 5-14 years were most likely to have slept under nets of poor quality (odds ratio 1.41; <it>p </it>= 0.007).</p> <p>Conclusions</p> <p>Although net ownership was high following increased delivery of ITNs, continuous promotion of effective maintenance and routine use is needed and efforts to replace damaged nets must be implemented.</p

Improving equity in malaria treatment: Relationship of socio-economic status with health seeking as well as with perceptions of ease of using the services of different providers for the treatment of malaria in Nigeria

<p>Abstract</p> <p>Background</p> <p>Equitable improvement of treatment-seeking for malaria will depend partly on how different socio-economic groups perceive the ease of accessing and utilizing malaria treatment services from different healthcare providers. Hence, it was important to investigate the link between socioeconomic status (SES) with differences in perceptions of ease of accessing and receiving treatment as well as with actual health seeking for treatment of malaria from different providers.</p> <p>Methods</p> <p>Structured questionnaires were used to collect data from 1,351 health providers in four malaria-endemic communities in Enugu state, southeast Nigeria. Data was collected on the peoples' perceptions of ease of accessibility and utilization of different providers of malaria treatment using a pre-tested questionnaire. A SES index was used to examine inequities in perceptions and health seeking.</p> <p>Results</p> <p>Patent medicine dealers (vendors) were the most perceived easily accessible providers, followed by private hospitals/clinics in two communities with full complement of healthcare providers: public hospital in the community with such a health provider and traditional healers in a community that is devoid of public healthcare facilities. There were inequities in perception of accessibility and use of different providers. There were also inequity in treatment-seeking for malaria and the poor spend proportionally more to treat the disease.</p> <p>Conclusion</p> <p>Inequities exist in how different SES groups perceive the levels of ease of accessibility and utilization of different providers for malaria treatment. The differentials in perceptions of ease of access and use as well as health seeking for different malaria treatment providers among SES groups could be decreased by reducing barriers such as the cost of treatment by making health services accessible, available and at reduced cost for all groups.</p