| 1. |
- Adamowicz, Tomasz, et al.
(författare)
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Regularity of p(.)-superharmonic functions, the Kellogg property and semiregular boundary points
- 2014
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Ingår i: Annales de l'Institut Henri Poincare. Analyse non linéar. - : Elsevier Masson / Institute Henri Poincar�. - 0294-1449 .- 1873-1430. ; 31:6, s. 1131-1153
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Tidskriftsartikel (refereegranskat)abstract
- We study various boundary and inner regularity questions for p(.)-(super)harmonic functions in Euclidean domains. In particular, we prove the Kellogg property and introduce a classification of boundary points for p(.)-harmonic functions into three disjoint classes: regular, semiregular and strongly irregular points. Regular and especially semiregular points are characterized in many ways. The discussion is illustrated by examples. Along the way, we present a removability result for bounded p(.)-harmonic functions and give some new characterizations of W-0(1,p(.)) spaces. We also show that p(.)-superharmonic functions are lower semicontinuously regularized, and characterize them in terms of lower semicontinuously regularized supersolutions.
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| 2. |
- Alvino, Angelo, et al.
(författare)
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Well-posed elliptic Neumann problems involving irregular data and domains
- 2010
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Ingår i: ANNALES DE L INSTITUT HENRI POINCARE-ANALYSE NON LINEAIRE. - : GAUTHIER-VILLARS/EDITIONS ELSEVIER, 23 RUE LINOIS, 75015 PARIS, FRANCE. - 0294-1449 .- 1873-1430. ; 27:4, s. 1017-1054
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Tidskriftsartikel (refereegranskat)abstract
- Non-linear elliptic Neumann problems, possibly in irregular domains and with data affected by low integrability properties, are taken into account. Existence, uniqueness and continuous dependence on the data of generalized solutions are established under a suitable balance between the integrability of the datum and the (ir)regularity of the domain. The latter is described in terms of isocapacitary inequalities. Applications to various classes of domains are also presented. (C) 2010 Elsevier Masson SAS. All rights reserved.
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| 3. |
- Björn, Anders, et al.
(författare)
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BMO, integrability, Harnack and Caccioppoli inequalities for quasiminimizers
- 2010
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Ingår i: ANNALES DE L INSTITUT HENRI POINCARE-ANALYSE NON LINEAIRE. - : GAUTHIER-VILLARS/EDITIONS ELSEVIER, 23 RUE LINOIS, 75015 PARIS, FRANCE. - 0294-1449 .- 1873-1430. ; 27:6, s. 1489-1505
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we use quasiminimizing properties of radial power-type functions to deduce counterexamples to certain Caccioppoli type inequalities and weak Harnack inequalities for quasisuperharmonic functions both of which are well known to hold for p-superharmonic functions We also obtain new bounds on the local integrability for quasisuperharmonic functions Furthermore we show that the logarithm of a positive quasisuperminimizer has bounded mean oscillation and belongs to a Sobolev type space
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| 4. |
- Carlsson Tedgren, Åsa, et al.
(författare)
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Comparison of high-dose-rate Ir-192 source strength measurements using equipment with traceability to different standards
- 2014
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Ingår i: Brachytherapy. - : Elsevier. - 1538-4721 .- 1873-1449. ; 13:4, s. 420-423
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE:According to the American Association of Physicists in Medicine Task Group No. 43 (TG-43) formalism used for dose calculation in brachytherapy treatment planning systems, the absolute level of absorbed dose is determined through coupling with the measurable quantity air-kerma strength or the numerically equal reference air-kerma rate (RAKR). Traceability to established standards is important for accurate dosimetry in laying the ground for reliable comparisons of results and safety in adoption of new treatment protocols. The purpose of this work was to compare the source strength for a high-dose rate (HDR) (192)Ir source as measured using equipment traceable to different standard laboratories in Europe and the United States.METHODS AND MATERIALS:Source strength was determined for one HDR (192)Ir source using four independent systems, all with traceability to different primary or interim standards in the United States and Europe.RESULTS:The measured HDR (192)Ir source strengths varied by 0.8% and differed on average from the vendor value by 0.3%. Measurements with the well chambers were 0.5% ± 0.1% higher than the vendor-provided source strength. Measurements with the Farmer chamber were 0.7% lower than the average well chamber results and 0.2% lower than the vendor-provided source strength. All of these results were less than the reported source calibration uncertainties (k=2) of each measurement system.CONCLUSIONS:In view of the uncertainties in ion chamber calibration factors, the maximum difference in source strength found in this study is small and confirms the consistency between calibration standards in use for HDR (192)Ir brachytherapy.
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| 5. |
- Karlsson, Mattias, et al.
(författare)
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Monte Carlo dosimetry of the eye plaque design used at the St. Erik Eye Hospital for I-125 brachytherapy
- 2014
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Ingår i: Brachytherapy. - : Elsevier. - 1538-4721 .- 1873-1449. ; 13:6, s. 651-656
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: At St. Erik Eye Hospital in Stockholm, Sweden, ocular tumors of apical height above 6 mm are treated with brachytherapy, using iodine-125 seeds attached to a gold alloy plaque while the treatment planning is performed assuming homogeneous water surroundings. The aim of this work was to investigate the dose-modifying effects of the plaque and the seed fixating silicone rubber glue. METHODS AND MATERIALS: The impact of the gold plaque and silicone rubber glue was studied with the Monte Carlo N-particle transport code, version 5. RESULTS: For the 2 cm most proximal to the plaque surface along the plaques central axis, the eyeball received 104.6-93.0% of the dose in all-water conditions. CONCLUSIONS: The 0.3 mm thick layer of silicone rubber glue, used for seed fixation, attenuates photons little enough to allow characteristic X-rays from the gold alloy plaque to reach the eyeball. Close to the plaque, the dose rates were higher with the plaque and glue present, than in homogeneous water conditions. This is in contrast to what has been reported for more commonly used eye plaques, demonstrating the importance of investigating the dosimetry of individual treatment systems.
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| 6. |
- Lewis, John L., et al.
(författare)
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Regularity of flat free boundaries in two-phase problems for the p-Laplace operator
- 2012
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Ingår i: Annales de l'Institut Henri Poincare. Analyse non linéar. - : European Mathematical Society - EMS - Publishing House GmbH. - 0294-1449 .- 1873-1430. ; 29:1, s. 83-108
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we continue the study in Lewis and Nystrom (2010) [19], concerning the regularity of the free boundary in a general two-phase free boundary problem for the p-Laplace operator, by proving regularity of the free boundary assuming that the free boundary is close to a Lipschitz graph.
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| 7. |
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