Brane-World Gravity

The observable universe could be a 1+3-surface (the "brane") embedded in a 1+3+\textit{d}-dimensional spacetime (the "bulk"), with Standard Model particles and fields trapped on the brane while gravity is free to access the bulk. At least one of the \textit{d} extra spatial dimensions could be very large relative to the Planck scale, which lowers the fundamental gravity scale, possibly even down to the electroweak ($\sim$ TeV) level. This revolutionary picture arises in the framework of recent developments in M theory. The 1+10-dimensional M theory encompasses the known 1+9-dimensional superstring theories, and is widely considered to be a promising potential route to quantum gravity. At low energies, gravity is localized at the brane and general relativity is recovered, but at high energies gravity "leaks" into the bulk, behaving in a truly higher-dimensional way. This introduces significant changes to gravitational dynamics and perturbations, with interesting and potentially testable implications for high-energy astrophysics, black holes, and cosmology. Brane-world models offer a phenomenological way to test some of the novel predictions and corrections to general relativity that are implied by M theory. This review analyzes the geometry, dynamics and perturbations of simple brane-world models for cosmology and astrophysics, mainly focusing on warped 5-dimensional brane-worlds based on the Randall--Sundrum models. We also cover the simplest brane-world models in which 4-dimensional gravity on the brane is modified at \emph{low} energies -- the 5-dimensional Dvali--Gabadadze--Porrati models. Then we discuss co-dimension two branes in 6-dimensional models.Comment: A major update of Living Reviews in Relativity 7:7 (2004) "Brane-World Gravity", 119 pages, 28 figures, the update contains new material on RS perturbations, including full numerical solutions of gravitational waves and scalar perturbations, on DGP models, and also on 6D models. A published version in Living Reviews in Relativit

Self evaluation of communication experiences after laryngeal cancer – A longitudinal questionnaire study in patients with laryngeal cancer

<p>Abstract</p> <p>Background</p> <p>Aim of this longitudinal study was to investigate the sensitivity to change of the Swedish Self Evaluation of Communication Experiences after Laryngeal Cancer questionnaire (the S-SECEL), addressing communication dysfunction in patients treated for laryngeal cancer. Previous studies have highlighted the need for more specific questionnaires for this purpose.</p> <p>Methods</p> <p>100 patients with Tis-T4 laryngeal cancer were included prior to treatment onset. Patients answered four questionnaires at six occasions during one year; the S-SECEL, the European Organisation for Research and Treatment of Cancer (EORTC) Core Quality of Life Core Questionnaire (QLQ-C30) supplemented by the Head and Neck cancer module (QLQ-H&N35) and the Hospital Anxiety and Depression (HAD) scale. In addition, performance status was assessed. Differences within groups were tested with the Wilcoxon paired signed ranks test and between-group analyses were carried out using the Mann-Whitney <it>U </it>test. Magnitude of group differences was analyzed by means of effect sizes.</p> <p>Results</p> <p>The S-SECEL was well accepted with a response rate of 76%. Communication dysfunction increased at 1 month, followed by a continuous decrease throughout the year. Changes were statistically significant at most measurement, demonstrating the sensitivity of the S-SECEL to changes in communication over time. The S-SECEL and the EORTC QLQ-C30 with the QLQ-H&N35 demonstrated similar results; however the S-SECEL was more sensitive regarding communication dysfunction. The largest changes were found in the most diagnose specific items concerning voice and speech.</p> <p>Conclusion</p> <p>The S-SECEL was investigated in the largest Scandinavian longitudinal study concerning health-related quality of life (HRQL) in laryngeal cancer patients. The questionnaire was responsive to change and showed convergent results when compared to established HRQL questionnaires. Our findings also indicate that the S-SECEL could be a more suitable instrument than the EORTC QLQ-C30 with QLQ-H&N35 when measuring communication experiences in patients with laryngeal cancer; it is more sensitive, shorter and can be used on an individual basis. As a routine screening instrument the S-SECEL could be a valuable tool for identifying patients at risk for psychosocial problems and to help plan rehabilitation. It is therefore recommended for clinical use in evaluation of communication dysfunction for all patients with laryngeal cancer irrespective of treatment.</p