154 research outputs found

    The geodesic structure of the Schwarzschild Anti-de Sitter black hole

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    In the present work we found the geodesic structure of an AdS black hole. By means of a detailed analyze of the corresponding effective potentials for particles and photon, we found all the possible motions which are allowed by the energy levels. Radial and non radial trajectories were exactly evaluated for both geodesics. The founded orbits were plotted in order to have a direct visualization of the allowed motions. We show that the geodesic structure of this black hole presents new type of motions not allowed by the Schwarzschild spacetime.Comment: 17 pages, 11 figure

    Optimizing the diagnostic work-up of acute uncomplicated urinary tract infections

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    <p>Abstract</p> <p>Background</p> <p>Most diagnostic tests for acute uncomplicated urinary tract infections (UTIs) have been previously studied in so-called single-test evaluations. In practice, however, clinicians use more than one test in the diagnostic work-up. Since test results carry overlapping information, results from single-test studies may be confounded. The primary objective of the Amsterdam Cystitis/Urinary Tract Infection Study (ACUTIS) is to determine the (additional) diagnostic value of relevant tests from patient history and laboratory investigations, taking into account their mutual dependencies. Consequently, after suitable validation, an easy to use, multivariable diagnostic rule (clinical index) will be derived.</p> <p>Methods</p> <p>Women who contact their GP with painful and/or frequent micturition undergo a series of possibly relevant tests, consisting of patient history questions and laboratory investigations. Using urine culture as the reference standard, two multivariable models (diagnostic indices) will be generated: a model which assumes that patients attend the GP surgery and a model based on telephone contact only. Models will be made more robust using the bootstrap. Discrimination will be visualized in high resolution histograms of the posterior UTI probabilities and summarized as 5<sup>th</sup>, 10<sup>th</sup>, 25<sup>th </sup>50<sup>th</sup>, 75<sup>th</sup>, 90<sup>th</sup>, and 95<sup>th </sup>centiles of these, Brier score and the area under the receiver operating characteristics curve (ROC) with 95% confidence intervals. Using the regression coefficients of the independent diagnostic indicators, a diagnostic rule will be derived, consisting of an efficient set of tests and their diagnostic values.</p> <p>The course of the presenting complaints is studied using 7-day patient diaries. To learn more about the natural history of UTIs, patients will be offered the opportunity to postpone the use of antibiotics.</p> <p>Discussion</p> <p>We expect that our diagnostic rule will allow efficient diagnosis of UTIs, necessitating the collection of diagnostic indicators with proven added value. GPs may use the rule (preferably after suitable validation) to estimate UTI probabilities for women with different combinations of test results. Finally, in a subcohort, an attempt is made to identify which indicators (including antibiotic treatment) are useful to prognosticate recovery from painful and/or frequent micturition.</p

    Polyamines and cancer: old molecules, new understanding

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    The amino-acid-derived polyamines have long been associated with cell growth and cancer, and specific oncogenes and tumour-suppressor genes regulate polyamine metabolism. Inhibition of polyamine synthesis has proven to be generally ineffective as an anticancer strategy in clinical trials, but it is a potent cancer chemoprevention strategy in preclinical studies. Clinical trials, with well-defined goals, are now underway to evaluate the chemopreventive efficacy of inhibitors of polyamine synthesis in a range of tissues

    Modified Luneburg lenses

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    Encounters with doctors: quantity and quality

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    Continuity of care and the large numbers of health care professionals who deliver that care are issues that frequently concern patients and their families. This study examined the number of doctors encountered by 50 patients, during the period of their cancer care. This ranged from 4 months to 26 years, with a median time of 2 years and 4 months. The doctors included in this number were general practitioners, doctors met during hospital inpatient admissions and when attending outpatient appointments, and doctors at the hospice. Descriptive statistics are included detailing the total number of doctors encountered by patients; the number met by patients within the first year of their cancer care; and the average number of new doctors met each year.The minimum number of doctors met was 13, maximum 97 and median 32. Notable examples include one patient who met 31 doctors during a 6-month period, and one patient who met 73 doctors during a period of 2 years and 1 month. Patients in this study with a history of less than 1 year met 28 doctors on average.Semi-structured interviews with these patients were conducted adopting a qualitative approach. Patients were asked about their recollections of the doctors they had met during their cancer care and what value they attributed to these encounters. Interviews were subject to thematic analysis. The major themes to emerge were: continuity of care, the provision of information and explanations and honesty in that process, breaking of bad news, the manner adopted by the doctor and issues relating to specialist referral.The large number of health care professionals, including the doctors quantified in this study, involved in the care of each patient represents a major challenge to ‘seamless’ and consistent communication between those involved
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