scholarly journals Principal component analysis of the nonlinear coupling of harmonic modes in heavy-ion collisions

2018 ◽  
Vol 97 (3) ◽  
Author(s):  
Piotr Bożek
Keyword(s):  
Principal Component Analysis ◽  
Heavy Ion Collisions ◽  
Principal Component ◽  
Component Analysis ◽  
Heavy Ion ◽  
Nonlinear Coupling ◽  
Ion Collisions

scholarly journals Principal component analysis of collective flow in relativistic heavy-ion collisions

2019 ◽  
Vol 79 (10) ◽  
Author(s):  
Ziming Liu ◽  
Wenbin Zhao ◽  
Huichao Song
Keyword(s):  
Principal Component Analysis ◽  
Mode Coupling ◽  
Principal Component ◽  
Component Analysis ◽  
Heavy Ion ◽  
Relativistic Heavy Ion Collisions ◽  
Human Beings ◽  
Hydrodynamic Simulations ◽  
Particle Distributions ◽  
Ion Collisions

Abstract In this paper, we implement principal component analysis (PCA) to study the single particle distributions generated from thousands of $$\mathtt {VISH2+1}$$VISH2+1 hydrodynamic simulations with an aim to explore if a machine could directly discover flow from the huge amount of data without explicit instructions from human-beings. We found that the obtained PCA eigenvectors are similar to but not identical with the traditional Fourier bases. Correspondingly, the PCA defined flow harmonics $$v_n^\prime $$vn′ are also similar to the traditional $$v_n$$vn for $$n=2$$n=2 and 3, but largely deviated from the Fourier ones for $$n\ge 4$$n≥4. A further study on the symmetric cumulants and the Pearson coefficients indicates that mode-coupling effects are reduced for these flow harmonics defined by PCA.

A German version of the Intermittent Claudication Questionnaire (ICQ): cultural adaptation and validation

VASA ◽  
2012 ◽  
Vol 41 (5) ◽  
pp. 333-342 ◽  
Author(s):  
Kirchberger ◽  
Finger ◽  
Müller-Bühl
Keyword(s):  
Principal Component Analysis ◽  
Intermittent Claudication ◽  
Completion Time ◽  
Short Form ◽  
Principal Component ◽  
Component Analysis ◽  
German Version ◽  
Average Completion Time ◽  
Sf 36 ◽  
Related Quality

Background: The Intermittent Claudication Questionnaire (ICQ) is a short questionnaire for the assessment of health-related quality of life (HRQOL) in patients with intermittent claudication (IC). The objective of this study was to translate the ICQ into German and to investigate the psychometric properties of the German ICQ version in patients with IC. Patients and methods: The original English version was translated using a forward-backward method. The resulting German version was reviewed by the author of the original version and an experienced clinician. Finally, it was tested for clarity with 5 German patients with IC. A sample of 81 patients were administered the German ICQ. The sample consisted of 58.0 % male patients with a median age of 71 years and a median IC duration of 36 months. Test of feasibility included completeness of questionnaires, completion time, and ratings of clarity, length and relevance. Reliability was assessed through a retest in 13 patients at 14 days, and analysis of Cronbach’s alpha for internal consistency. Construct validity was investigated using principal component analysis. Concurrent validity was assessed by correlating the ICQ scores with the Short Form 36 Health Survey (SF-36) as well as clinical measures. Results: The ICQ was completely filled in by 73 subjects (90.1 %) with an average completion time of 6.3 minutes. Cronbach’s alpha coefficient reached 0.75. Intra-class correlation for test-retest reliability was r = 0.88. Principal component analysis resulted in a 3 factor solution. The first factor explained 51.5 of the total variation and all items had loadings of at least 0.65 on it. The ICQ was significantly associated with the SF-36 and treadmill-walking distances whereas no association was found for resting ABPI. Conclusions: The German version of the ICQ demonstrated good feasibility, satisfactory reliability and good validity. Responsiveness should be investigated in further validation studies.

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