Beam losses along the ESS LINAC due to nonlinear effects - A Statistical review

In this project, a comprehensive statistical review is done regarding beam distribution evolution and losses of protons in the ESS LINAC. It aims to clarify some unanswered questions regarding the change in the distribution as it evolves through the LINAC and how sudden changes can effect the losses of protons downstream. The correlation between the sub phase-spaces were removed to be able to study the nonlinear forces acting on the distribution. Several statistical tools were used to analyse these distributions and visualize them in a comprehensive manner. Furthermore, this report aims to give an overview of the maximum losses that one may expect in the current lattice configuration in the ESS LINAC. An EVT (Extreme Value Theory) approach was used to model these extreme losses to highlight extreme scenarios in the LINAC. Many interesting features arise regarding the distribution evolution which can be confirmed in theory and the maximum losses could be regarded as within the limit set by the ESS design report. The results illustrates that changes in the distribution can be found with the KS-test and can act complementary to the tools used by the physicists today, with a little refinements. Furthermore, the GMM may indicate that the distributions are multimodal, thus opening the questions around the interpretation of the moments of the distributions and their relation to the tools used for analysis. The EVT approach showed that no concern is needed regarding the exceedances of the proposed highest limit of losses, 1 W/m. In conclusion, the report highlights statistical tools for beam monitoring and further research in this subject may be of scientific interest

Distribution and extreme loss analysis in the ESS linac : A statistical perspective

The report takes a statistical approach in the study of distribution evolution of the proton beam within the ESS linac and reports a new technique of pinpointing the non-linear space-charge effect of the propagating proton beam. By using the test statistic from the nonparametric Kolmogorov-Smirnov test the author visualises the change in the normalised distributions by looking at the supremum distance between the cumulative distribution functions in comparison, and the propagation of the deviation throughout the ESS linac. This approach identifies changes in the distribution which may cause losses in the linac and highlights the parts where the space-charge has big impact on the beam distribution. Also, an Extreme Value Theory approach is adopted in order to quantify the effects of the non linear forces affecting the proton beam distribution

Frailty and Recurrent Hospitalization After Transcatheter Aortic Valve Replacement

Background For frail patients with limited life expectancy, time in hospital following transcatheter aortic valve replacement is an important measure of quality of life; however, data remain scarce. Thus, we aimed to investigate frailty and its relation to time in hospital during the first year after transcatheter aortic valve replacement. Methods and Results From 2008 to 2020, all Danish patients who underwent transcatheter aortic valve replacement and were alive at discharge were included. Using the validated Hospital Frailty Risk Score, patients were categorized in the low, intermediate, and high frailty groups. Time in hospital and mortality up to 1 year are reported according to frailty groups. In total, 3437 (57.6%), 2277 (38.1%), and 257 (4.3%) were categorized in the low, intermediate, and high frailty groups, respectively. Median age was ≈81 years. Female sex and comorbidity burden were incrementally higher across frailty groups (low frailty: heart failure, 24.1%; stroke, 7.2%; and chronic kidney disease, 4.5%; versus high frailty: heart failure, 42.8%; stroke, 34.2%; and chronic kidney disease, 29.2%). In the low frailty group, 50.5% survived 1 year without a hospital admission, 10.8% were hospitalized >15 days, and 5.8% of patients died. By contrast, 26.1% of patients in the high frailty group survived 1 year without a hospital admission, 26.4% were hospitalized >15 days, and 15.6% died within 1 year. Differences persisted in models adjusted for sex, age, frailty, and comorbidity burden (excluding overlapping comorbidities). Conclusions Among patients undergoing transcatheter aortic valve replacement, frailty is strongly associated with time in hospital and mortality. Prevention strategies for frail patients to reduce hospitalization burden could be beneficial