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Université de Fribourg

Revealing ‘plasmaron’ feature in DySb by optical spectroscopy study

Ban, W J ; Wu, D S ; Xu, Bing ; Luo, J L ; Xiao, Hong

In: Journal of Physics: Condensed Matter, 2019, vol. 31, no. 40, p. 405701

We report magnetic susceptibility, resistivity and optical spectroscopy study on single crystal sample DySb. It exhibits extremely large magnetoresistance (XMR), and a magnetic phase transition from paramagnetic (PM) to antiferromagnetic (AFM) state at about 10 K. A 'screened' plasma edge at about 4000 cm−1 is revealed by optical measurement, which suggests that the material has a low...

Haute école de gestion de Genève

A macroeconomic perspective on the rise of second-tier cities in the national and globalizing context of China

Cadez, Fabien ; Cadez, Fabien (Dir.)

Mémoire de bachelor : Haute école de gestion de Genève, 2015 ; TDEE 278.

Since China’s economic reforms in the late 1970s, foreign investments have initially flooded the so-called “first-tier cities” including Shanghai, Beijing, or even Shenzhen or Guangzhou. Due to rising labour costs, growing constraints over natural resources, long-term inflation and environmental issues among others (Zhuang et al. 2012; Zuojun, 2012), they have been undertaking structural...

Université de Fribourg

Scaling and memory in recurrence intervals of Internet traffic

Cai, Shi-Min ; Fu, Zhong-Qian ; Zhou, Tao ; Gu, Jun ; Zhou, Pei-Ling

In: Europhysics Letters, 2009, vol. 87, p. 68001

By studying the statistics of recurrence intervals, τ, between volatilities of Internet traffic rate changes exceeding a certain threshold q, we find that the probability distribution functions, Pq(τ), for both byte and packet flows, show scaling property as $P_{q}(\tau)=\frac{1}{\overline{\tau}}f(\frac{\tau}{\overline{\tau}})$. The scaling functions for both byte and packet flows obey the...

Université de Fribourg

Muon spin rotation study of magnetism and superconductivity in BaFe2−xCoxAs₂ and Pr1−xSrxFeAsO

Bernhard, Christian ; Drew, Alan J. ; Schulz, Leander ; Malik, Vivek Kumar ; Rössle, Matthias ; Niedermayer, Ch. ; Wolf, Th. ; Varma, G. D. ; Mu, G. ; Wen, H.-H. ; Liu, H. ; Wu, G. ; Chen, X. H.

In: New Journal of Physics, 2009, vol. 11, p. 055050

We present a muon spin rotation (μSR) study of the magnetic and superconducting properties of single crystals of electron-doped BaFe2−xCoxAs₂ with x = 0.08, 0.20 and 0.25 (Tc = 9, 25 and 20 K) and of polycrystalline hole-doped Pr1−xSrxFeAsO with x = 0 and 0.2 (Tc = 15...

Université de Fribourg

Scale invariance of human electroencephalogram signals in sleep

Cai, Shi-Min ; Jiang, Zhao-Hui ; Zhou, Tao ; Zhou, Pei-Ling ; Yang, Hui-Jie ; Wang, Bing-Hong

In: Physical Review E, 2007, vol. 76, p. 061903

In this paper, we investigate the dynamical properties of electroencephalogram (EEG) signals of humans in sleep. By using a modified random walk method, we demonstrate that scale-invariance is embedded in EEG signals after a detrending procedure is applied. Furthermore, we study the dynamical evolution of the probability density function (PDF) of the detrended EEG signals by nonextensive...

Université de Fribourg

Fat tails, long memory, maturity and ageing in open-source software projects

Challet, Damien ; Valverde, Sergi

We report activity data analysis on several open source software projects, focusing on time between modifications and on the number of files modified at once. Both have fat-tailed distributions, long-term memory, and display systematic non-trivial cross-correlations, suggesting that quiet periods are followed by cascading modifications. In addition the maturity of a software project can be...

Université de Fribourg

Scaling behaviour and memory in heart rate of healthy human

Cai, Shi-Min ; Peng, Hu ; Yang, Hui-Jie ; Zhou, Tao ; Zhou, Pei-Ling ; Wang, Bing-Hong

In: Chinese Physics Letters, 2007, vol. 24, no. 10, p. 3002

We investigate a set of complex heart rate time series from healthy human in different behaviour states with the detrended fluctuation analysis and diffusion entropy (DE) method. It is proposed that the scaling properties are influenced by behaviour states. The memory detected by DE exhibits an approximately same pattern after a detrending procedure. Both of them demonstrate the long-range strong...

Università della Svizzera italiana

A robust approach for skewed and heavy-tailed outcomes in the analysis of health care expenditures

Cantoni, Eva ; Ronchetti, Elvezio

In: Journal of Health Economics, 2006, vol. 25, no. 2, p. 198-213

In this paper robust statistical procedures are presented for the analysis of skewed and heavy-tailed outcomes as they typically occur in health care data. The new estimators and test statistics are extensions of classical maximum likelihood techniques for generalized linear models. In contrast to their classical counterparts, the new robust techniques show lower variability and excellent...