Cosmic Strings Stabilized by Fermion Fluctuations

We provide a thorough exposition of recent results on the quantum stabilization of cosmic strings. Stabilization occurs through the coupling to a heavy fermion doublet in a reduced version of the standard model. The study combines the vacuum polarization energy of fermion zero-point fluctuations and the binding energy of occupied energy levels, which are of the same order in a semi-classical expansion. Populating these bound states assigns a charge to the string. Strings carrying fermion charge become stable if the Higgs and gauge fields are coupled to a fermion that is less than twice as heavy as the top quark. The vacuum remains stable in the model, because neutral strings are not energetically favored. These findings suggest that extraordinarily large fermion masses or unrealistic couplings are not required to bind a cosmic string in the standard model.Comment: Based on talk by HW at QFEXT 11 (Benasque, Spain), 15p, uses ws-ijmpcs.cls (incl

The impact of consent on observational research: a comparison of outcomes from consenters and non consenters to an observational study

Background Public health benefits from research often rely on the use of data from personal medical records. When neither patient consent nor anonymisation is possible, the case for accessing such records for research purposes depends on an assessment of the probabilities of public benefit and individual harm. Methods In the late 1990s, we carried out an observational study which compared the care given to affluent and deprived women with breast cancer. Patient consent was not required at that time for review of medical records, but was obtained later in the process prior to participation in the questionnaire study. We have re-analysed our original results to compare the whole sample with those who later provided consent. Results Two important findings emerged from the re-analysis of our data which if presented initially would have resulted in insufficient and inaccurate reporting. Firstly, the reduced dataset contains no information about women presenting with locally advanced or metastatic cancer and we would have been unable to demonstrate one of our initial key findings: namely a larger number of such women in the deprived group. Secondly, our re-analysis of the consented women shows that significantly more women from deprived areas (51 v 31%, p = 0.018) received radiotherapy compared to women from more affluent areas. Previously published data from the entire sample demonstrated no difference in radiotherapy treatment between the affluent and deprived groups. Conclusion The risk benefit assessment made regarding the use of medical records without consent should include the benefits of obtaining research evidence based on 100% of the population and the possibility of inappropriate or insufficient findings if research is confined to consented populations

The new paradigm of hepatitis C therapy: integration of oral therapies into best practices.

Emerging data indicate that all-oral antiviral treatments for chronic hepatitis C virus (HCV) will become a reality in the near future. In replacing interferon-based therapies, all-oral regimens are expected to be more tolerable, more effective, shorter in duration and simpler to administer. Coinciding with new treatment options are novel methodologies for disease screening and staging, which create the possibility of more timely care and treatment. Assessments of histologic damage typically are performed using liver biopsy, yet noninvasive assessments of histologic damage have become the norm in some European countries and are becoming more widespread in the United States. Also in place are new Centers for Disease Control and Prevention (CDC) initiatives to simplify testing, improve provider and patient awareness and expand recommendations for HCV screening beyond risk-based strategies. Issued in 2012, the CDC recommendations aim to increase HCV testing among those with the greatest HCV burden in the United States by recommending one-time testing for all persons born during 1945-1965. In 2013, the United States Preventive Services Task Force adopted similar recommendations for risk-based and birth-cohort-based testing. Taken together, the developments in screening, diagnosis and treatment will likely increase demand for therapy and stimulate a shift in delivery of care related to chronic HCV, with increased involvement of primary care and infectious disease specialists. Yet even in this new era of therapy, barriers to curing patients of HCV will exist. Overcoming such barriers will require novel, integrative strategies and investment of resources at local, regional and national levels

Reliability and validity of the AGREE instrument used by physical therapists in assessment of clinical practice guidelines

BACKGROUND: The AGREE instrument has been validated for evaluating Clinical Practice Guidelines (CPG) pertaining to medical care. This study evaluated the reliability and validity of physical therapists using the AGREE to assess quality of CPGs relevant to physical therapy practice. METHODS: A total of 69 physical therapists participated and were classified as generalists, specialist or researchers. Pairs of appraisers within each category evaluated independently, a set of 6 CPG selected at random from a pool of 55 CPGs. RESULTS: Reliability between pairs of appraisers indicated low to high reliability depending on the domain and number of appraisers (0.17–0.81 for single appraiser; 0.30–0.96 when score averaged across a pair of appraisers). The highest reliability was achieved for Rigour of Development, which exceeded ICC> 0.79, if scores from pairs of appraisers were pooled. Adding more than 3 appraisers did not consistently improve reliability. Appraiser type did not determine reliability scores. End-users, including study participants and a separate sample of 102 physical therapy students, found the AGREE useful to guide critical appraisal. The construct validity of the AGREE was supported in that expected differences on Rigour of Development domains were observed between expert panels versus those with no/uncertain expertise (differences of 10–21% p = 0.09–0.001). Factor analysis with varimax rotation, produced a 4-factor solution that was similar, although not in exact agreement with the AGREE Domains. Validity was also supported by the correlation observed (Kendall-tao = 0.69) between Overall Assessment and the Rigour of Development domain. CONCLUSION: These findings suggest that the AGREE instrument is reliable and valid when used by physiotherapists to assess the quality of CPG pertaining to physical therapy health services

The Casimir effect as scattering problem

We show that Casimir-force calculations for a finite number of non-overlapping obstacles can be mapped onto quantum-mechanical billiard-type problems which are characterized by the scattering of a fictitious point particle off the very same obstacles. With the help of a modified Krein trace formula the genuine/finite part of the Casimir energy is determined as the energy-weighted integral over the log-determinant of the multi-scattering matrix of the analog billiard problem. The formalism is self-regulating and inherently shows that the Casimir energy is governed by the infrared end of the multi-scattering phase shifts or spectrum of the fluctuating field. The calculation is exact and in principle applicable for any separation(s) between the obstacles. In practice, it is more suited for large- to medium-range separations. We report especially about the Casimir energy of a fluctuating massless scalar field between two spheres or a sphere and a plate under Dirichlet and Neumann boundary conditions. But the formalism can easily be extended to any number of spheres and/or planes in three or arbitrary dimensions, with a variety of boundary conditions or non-overlapping potentials/non-ideal reflectors.Comment: 14 pages, 2 figures, plenary talk at QFEXT07, Leipzig, September 2007, some typos correcte

Echo in Optical Lattices: Stimulated Revival of Breathing Oscillations

We analyze a stimulated revival (echo) effect for the breathing modes of the atomic oscillations in optical lattices. The effect arises from the dephasing due to the weak anharmonicity being partly reversed in time by means of additional parametric excitation of the optical lattice. The shape of the echo response is obtained by numerically simulating the equation of motion for the atoms with subsequent averaging over the thermal initial conditions. A qualitative analysis of the phenomenon shows that the suggested echo mechanism combines the features of both spin and phonon echoes.Comment: 13 pages, 3 figure

Squeezing of Atoms in a Pulsed Optical Lattice

We study the process of squeezing of an ensemble of cold atoms in a pulsed optical lattice. The problem is treated both classically and quantum-mechanically under various thermal conditions. We show that a dramatic compression of the atomic density near the minima of the optical potential can be achieved with a proper pulsing of the lattice. Several strategies leading to the enhanced atomic squeezing are suggested, compared and optimized.Comment: Latex, 9 pages, 10 figures, submitted to PR

Maternal and perinatal guideline development in hospitals in South East Asia: the experience of the SEA-ORCHID project

<p>Abstract</p> <p>Background</p> <p>Clinical practice guidelines (CPGs) are commonly used to support practitioners to improve practice. However many studies have raised concerns about guideline quality. The reasons why guidelines are not developed following the established development methods are not clear.</p> <p>The SEA-ORCHID project aims to increase the generation and use of locally relevant research and improve clinical practice in maternal and perinatal care in four countries in South East Asia. Baseline data highlighted that development of evidence-based CPGs according to recommended processes was very rare in the SEA-ORCHID hospitals. The project investigators suggested that there were aspects of the recommended development process that made it very difficult in the participating hospitals.</p> <p>We therefore aimed to explore the experience of guideline development and particularly the enablers of and barriers to developing evidence-based guidelines in the nine hospitals in South East Asia participating in the SEA-ORCHID project, so as to better understand how evidence-based guideline development could be facilitated in these settings.</p> <p>Methods</p> <p>Semi-structured, face-to-face interviews were undertaken with senior and junior healthcare providers (nurses, midwives, doctors) from the maternal and neonatal services at each of the nine participating hospitals. Interviews were audio-recorded, transcribed and a thematic analysis undertaken.</p> <p>Results</p> <p>Seventy-five individual, 25 pair and eleven group interviews were conducted. Participants clearly valued evidence-based guidelines. However they also identified several major barriers to guideline development including time, lack of awareness of process, difficulties searching for evidence and arranging guideline development group meetings, issues with achieving multi-disciplinarity and consumer involvement. They also highlighted the central importance of keeping guidelines up-to-date.</p> <p>Conclusion</p> <p>Healthcare providers in the SEA-ORCHID hospitals face a series of barriers to developing evidence-based guidelines. At present, in many hospitals, several of these barriers are insurmountable, and as a result, rigorous, evidence-based guidelines are not being developed. Given the acknowledged benefits of evidence-based guidelines, perhaps a new approach to supporting their development in these contexts is needed.</p

Development of evidence-based clinical practice guidelines (CPGs): comparing approaches

<p>Abstract</p> <p>Background</p> <p>While the potential of clinical practice guidelines (CPGs) to support implementation of evidence has been demonstrated, it is not currently being achieved. CPGs are both poorly developed and ineffectively implemented. To improve clinical practice and health outcomes, both well-developed CPGs and effective methods of CPG implementation are needed. We sought to establish whether there is agreement on the fundamental characteristics of an evidence-based CPG development process and to explore whether the level of guidance provided in CPG development handbooks is sufficient for people using these handbooks to be able to apply it.</p> <p>Methods</p> <p>CPG development handbooks were identified through a broad search of published and grey literature. Documents published in English produced by national or international organisations purporting to support development of evidence-based CPGs were included. A list of 14 key elements of a CPG development process was developed. Two authors read each handbook. For each handbook a judgement was made as to how it addressed each element; assigned as: 'mentioned and clear guidance provided', 'mentioned but limited practical detail provided ', or 'not mentioned'.</p> <p>Results</p> <p>Six CPG development handbooks were included. These were produced by the Council of Europe, the National Health and Medical Research Council of Australia, the National Institute for Health and Clinical Excellence in the UK, the New Zealand Guidelines Group, the Scottish Intercollegiate Guideline Network, and the World Health Organization (WHO).</p> <p>There was strong concordance between the handbooks on the key elements of an evidence-based CPG development process. All six of the handbooks require and provide guidance on establishment of a multidisciplinary guideline development group, involvement of consumers, identification of clinical questions or problems, systematic searches for and appraisal of research evidence, a process for drafting recommendations, consultation with others beyond the guideline development group, and ongoing review and updating of the CPG.</p> <p>Conclusion</p> <p>The key elements of an evidence-based CPG development process are addressed with strong concordance by existing CPG development handbooks. Further research is required to determine why these key elements are often not addressed by CPG developers.</p

Managing women in pregnancy after bariatric surgery: The midwife as the co-ordinator of care

Bariatric surgery is a recommended, cost-effective, evidenced-based intervention to reduce weight and associated comorbidities in severely obese people. People with a BMI of 40 kg/m2 or more, or a BMI between 35–40 kg/m2 with other medical conditions such as diabetes, hypertension, high cholesterol and obstructive sleep apnoea meet the criteria to be considered for bariatric surgery. Over the past 10 years, bariatric surgery in the UK has been more widely accessible and consequently midwives may be required to care for pregnant women who have undergone bariatric surgery such as a gastric band, sleeve gastrectomy and gastric bypass. Midwives are required to work co-operatively, recognising and working within the limits of their competence and providing leadership. The aim of this article is to consider the midwife's role as co-ordinator of care for pregnant women who have undergone bariatric surgery. It outlines the most common bariatric procedures and specific considerations, including nutritional supplementation required when providing care to women in the antenatal and postnatal period