Vortex corrections to universal scaling of magnetic fluctuations in 2D XY model

The vortex contribution to the probability density function of longitudinal magnetization fluctuations is examined in finite 2D XY systems close to the Kosterlitz-Thouless-Berezinskii transition temperature. Within the temperature range studied their relevance is limited to rare fluctuations, where they increase the probability of events exceeding four standard deviations below the mean magnetization.Comment: 6 pages, 4 figures. Refs adde

Emergent electrochemistry in spin ice: Debye-Hückel theory and beyond

International audienceWe present a detailed theoretical and experimental study to show how a model system for the investigation of classic electrolyte theory emerges in a nonelectrical context. In particular we develop the thermodynamic treatment of spin ice as a “magnetolyte,” a fluid of singly and doubly charged magnetic monopoles. This is equivalent to the electrochemical system 2H2O=H3O++OH−=H4O2++O2−, but with perfect symmetry between oppositely charged ions. For this lattice magnetolyte, we present an analysis going beyond Debye-Hückel theory to include Bjerrum pairs. This is accurate at all temperatures and incorporates “Dirac strings” imposed by the microscopic ice rule constraints at the level of Pauling's approximation. Our theory is in close agreement with the specific heat from numerical simulations as well as new experimental measurements with an improved lattice correction, which we present here, on the spin ice materials Ho2Ti2O7 and Dy2Ti2O7. Our results provide new experimental tests of Debye-Hückel theory and its extensions and yield insights into the electrochemical behavior of water ice and liquid water, which are closely related to the spin ice magnetolyte

Absence of Progression As Assessed by Response Evaluation Criteria in Solid Tumors Predicts Survival in Advanced GI Stromal Tumors Treated With Imatinib Mesylate: The Intergroup EORTC-ISG-AGITG Phase III Trial

PURPOSE: From February 2001 to February 2002, 946 patients with advanced GI stromal tumors (GISTs) treated with imatinib were included in a controlled EORTC/ISG/AGITG (European Organisation for Research and Treatment of Cancer/Italian Sarcoma Group/Australasian Gastro-Intestinal Trials Group) trial. This analysis investigates whether the response classification assessed by RECIST (Response Evaluation Criteria in Solid Tumors), predicts for time to progression (TTP) and overall survival (OS). PATIENTS AND METHODS: Per protocol, the first three disease assessments were done at 2, 4, and 6 months. For the purpose of the analysis (landmark method), disease response was subclassified in six categories: partial response (PR; > 30% size reduction), minor response (MR; 10% to 30% reduction), no change (NC) as either NC- (0% to 10% reduction) or NC+ (0% to 20% size increase), progressive disease (PD; > 20% increase/new lesions), and subjective PD (clinical progression). RESULTS: A total of 906 patients had measurable disease at entry. At all measurement time points, complete response (CR), PR, and MR resulted in similar TTP and OS; this was also true for NC- and NC+, and for PD and subjective PD. Patients were subsequently classified as responders (CR/PR/MR), NC (NC+/NC-), or PD. This three-class response categorization was found to be highly predictive of further progression or survival for the first two measurement points. After 6 months of imatinib, responders (CR/PR/MR) had the same survival prognosis as patients classified as NC. CONCLUSION: RECIST perfectly enables early discrimination between patients who benefited long term from imatinib and those who did not. After 6 months of imatinib, if the patient is not experiencing PD, the pattern of radiologic response by tumor size criteria has no prognostic value for further outcome. Imatinib needs to be continued as long as there is no progression according to RECIST