89 research outputs found

    Stationary Black Holes: Uniqueness and Beyond

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    The spectrum of known black-hole solutions to the stationary Einstein equations has been steadily increasing, sometimes in unexpected ways. In particular, it has turned out that not all black-hole-equilibrium configurations are characterized by their mass, angular momentum and global charges. Moreover, the high degree of symmetry displayed by vacuum and electro-vacuum black-hole spacetimes ceases to exist in self-gravitating non-linear field theories. This text aims to review some developments in the subject and to discuss them in light of the uniqueness theorem for the Einstein-Maxwell system.Comment: Major update of the original version by Markus Heusler from 1998. Piotr T. Chru\'sciel and Jo\~ao Lopes Costa succeeded to this review's authorship. Significantly restructured and updated all sections; changes are too numerous to be usefully described here. The number of references increased from 186 to 32

    Repaired tetralogy of Fallot: the roles of cardiovascular magnetic resonance in evaluating pathophysiology and for pulmonary valve replacement decision support

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    Surgical management of tetralogy of Fallot (TOF) results in anatomic and functional abnormalities in the majority of patients. Although right ventricular volume load due to severe pulmonary regurgitation can be tolerated for many years, there is now evidence that the compensatory mechanisms of the right ventricular myocardium ultimately fail and that if the volume load is not eliminated or reduced by pulmonary valve replacement the dysfunction might be irreversible. Cardiovascular magnetic resonance (CMR) has evolved during the last 2 decades as the reference standard imaging modality to assess the anatomic and functional sequelae in patients with repaired TOF. This article reviews the pathophysiology of chronic right ventricular volume load after TOF repair and the risks and benefits of pulmonary valve replacement. The CMR techniques used to comprehensively evaluate the patient with repaired TOF are reviewed and the role of CMR in supporting clinical decisions regarding pulmonary valve replacement is discussed

    Serum screening with Down's syndrome markers to predict pre-eclampsia and small for gestational age: Systematic review and meta-analysis

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    <p>Abstract</p> <p>Background</p> <p>Reliable antenatal identification of pre-eclampsia and small for gestational age is crucial to judicious allocation of monitoring resources and use of preventative treatment with the prospect of improving maternal/perinatal outcome. The purpose of this systematic review was to determine the accuracy of five serum analytes used in Down's serum screening for prediction of pre-eclampsia and/or small for gestational age.</p> <p>Methods</p> <p>The data sources included Medline, Embase, Cochrane library, Medion (inception to February 2007), hand searching of relevant journals, reference list checking of included articles, contact with experts. Two reviewers independently selected the articles in which the accuracy of an analyte used in Downs's serum screening before the 25<sup>th </sup>gestational week was associated with the occurrence of pre-eclampsia and/or small for gestational age without language restrictions. Two authors independently extracted data on study characteristics, quality and results.</p> <p>Results</p> <p>Five serum screening markers were evaluated. 44 studies, testing 169,637 pregnant women (4376 pre-eclampsia cases) and 86 studies, testing 382,005 women (20,339 fetal growth restriction cases) met the selection criteria. The results showed low predictive accuracy overall. For pre-eclampsia the best predictor was inhibin A>2.79MoM positive likelihood ratio 19.52 (8.33,45.79) and negative likelihood ratio 0.30 (0.13,0.68) (single study). For small for gestational age it was AFP>2.0MoM to predict birth weight < 10<sup>th </sup>centile with birth < 37 weeks positive likelihood ratio 27.96 (8.02,97.48) and negative likelihood ratio 0.78 (0.55,1.11) (single study). A potential clinical application using aspirin as a treatment is given as an example.</p> <p>There were methodological and reporting limitations in the included studies thus studies were heterogeneous giving pooled results with wide confidence intervals.</p> <p>Conclusion</p> <p>Down's serum screening analytes have low predictive accuracy for pre-eclampsia and small for gestational age. They may be a useful means of risk assessment or of use in prediction when combined with other tests.</p

    Nutrition and cancer: A review of the evidence for an anti-cancer diet

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    It has been estimated that 30–40 percent of all cancers can be prevented by lifestyle and dietary measures alone. Obesity, nutrient sparse foods such as concentrated sugars and refined flour products that contribute to impaired glucose metabolism (which leads to diabetes), low fiber intake, consumption of red meat, and imbalance of omega 3 and omega 6 fats all contribute to excess cancer risk. Intake of flax seed, especially its lignan fraction, and abundant portions of fruits and vegetables will lower cancer risk. Allium and cruciferous vegetables are especially beneficial, with broccoli sprouts being the densest source of sulforophane. Protective elements in a cancer prevention diet include selenium, folic acid, vitamin B-12, vitamin D, chlorophyll, and antioxidants such as the carotenoids (α-carotene, β-carotene, lycopene, lutein, cryptoxanthin). Ascorbic acid has limited benefits orally, but could be very beneficial intravenously. Supplementary use of oral digestive enzymes and probiotics also has merit as anticancer dietary measures. When a diet is compiled according to the guidelines here it is likely that there would be at least a 60–70 percent decrease in breast, colorectal, and prostate cancers, and even a 40–50 percent decrease in lung cancer, along with similar reductions in cancers at other sites. Such a diet would be conducive to preventing cancer and would favor recovery from cancer as well

    Tests of chameleon gravity

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    Theories of modified gravity, where light scalars with non-trivial self-interactions and non-minimal couplings to matter—chameleon and symmetron theories—dynamically suppress deviations from general relativity in the solar system. On other scales, the environmental nature of the screening means that such scalars may be relevant. The highly-nonlinear nature of screening mechanisms means that they evade classical fifth-force searches, and there has been an intense effort towards designing new and novel tests to probe them, both in the laboratory and using astrophysical objects, and by reinterpreting existing datasets. The results of these searches are often presented using different parametrizations, which can make it difficult to compare constraints coming from different probes. The purpose of this review is to summarize the present state-of-the-art searches for screened scalars coupled to matter, and to translate the current bounds into a single parametrization to survey the state of the models. Presently, commonly studied chameleon models are well-constrained but less commonly studied models have large regions of parameter space that are still viable. Symmetron models are constrained well by astrophysical and laboratory tests, but there is a desert separating the two scales where the model is unconstrained. The coupling of chameleons to photons is tightly constrained but the symmetron coupling has yet to be explored. We also summarize the current bounds on f(R) models that exhibit the chameleon mechanism (Hu and Sawicki models). The simplest of these are well constrained by astrophysical probes, but there are currently few reported bounds for theories with higher powers of R. The review ends by discussing the future prospects for constraining screened modified gravity models further using upcoming and planned experiments

    Providers’ preferences for pediatric oral health information in the electronic health record: a cross-sectional survey

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    Abstract Background The majority of primary care physicians support integration of children’s oral health promotion and disease prevention into their practices but can experience challenges integrating oral health services into their workflow. Most electronic health records (EHRs) in primary care settings do not include oral health information for pediatric patients. Therefore, it is important to understand providers’ preferences for oral health information within the EHR. The objectives of this study are to assess (1) the relative importance of various elements of pediatric oral health information for primary care providers to have in the EHR and (2) the extent to which practice and provider characteristics are associated with these information preferences. Methods We surveyed a sample of primary care physicians who conducted Medicaid well-child visits in North Carolina from August – December 2013. Using descriptive statistics, we analyzed primary care physicians’ oral health information preferences relative to their information preferences for traditional preventive aspects of well-child visits. Furthermore, we analyzed associations between oral health information preferences and provider- and practice-level characteristics using an ordinary least squares regression model. Results Fewer primary care providers reported that pediatric oral health information is “very important,” as compared to more traditional elements of primary care information, such as tracking immunizations. However, the majority of respondents reported some elements of oral health information as being very important. Also, we found positive associations between the percentage of well child visits in which oral health screenings and oral health referrals are performed and the reported importance of having pediatric oral health information in the EHR. Conclusions Incorporating oral health information into the EHR may be desirable for providers, particularly those who perform oral health screenings and dental referrals

    Quantum Spacetime Phenomenology

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    I review the current status of phenomenological programs inspired by quantum-spacetime research. I stress in particular the significance of results establishing that certain data analyses provide sensitivity to effects introduced genuinely at the Planck scale. And my main focus is on phenomenological programs that managed to affect the directions taken by studies of quantum-spacetime theories.Comment: 125 pages, LaTex. This V2 is updated and more detailed than the V1, particularly for quantum-spacetime phenomenology. The main text of this V2 is about 25% more than the main text of the V1. Reference list roughly double

    Design, planning and implementation lessons learnt from a surgical multi-centre randomised controlled trial

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    Background Increasingly, pragmatic randomised controlled trials are being used to evaluate surgical interventions, although they present particular difficulties in regards to recruitment and retention. Methods Procedures and processes related to implementation of a multi-centre pragmatic surgical randomised controlled trial are discussed. In this surgical trial, forecasting of consent rates based on similar trials and micro-costing of study activities with research partners were undertaken and a video was produced targeting recruiting staff with the aim of aiding recruitment. The baseline assessments were reviewed to ensure the timing did not impact on the outcome. Attrition due to procedure waiting time was monitored and data were triangulated for the primary outcome to ensure adequate follow-up data. Results Forecasting and costing ensured that the recruitment window was of adequate length and adequate resource was available for study procedures at multiple clinics in each hospital. Recruiting staff found the recruitment video useful. The comparison of patient-reported data collected prior to randomisation and prior to treatment provided confidence in the baseline data. Knowledge of participant dropout due to delays in treatment meant we were able to increase the recruitment target in a timely fashion, and along with the triangulation of data sources, this ensured adequate follow-up of randomised participants. Conclusions This paper provides a range of evidence-based and experience-based approaches which, collectively, resulted in meeting our study objectives and from which lessons may be transferable
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