Lessons on internal erosion in embankment dams from failures and physical models (Keynote)

The investigations of embankment failures reported by Erinoh R&D project, merged with the Foster & Fell Erdata and NPDP program in the USA, point out the main causes and the main situations where internal erosion could initiate and trigger the failure of dams. The investigation of physical models built in the CACOH laboratory of CNR shows under particular circumstances (piping at core base) pervious shells cannot provide enough weight or erosion resistance to resist concentrated leaks. Three different mechanisms of failure may occur: (1) general instability without hydraulic fracturing, (2) hydraulic fracturing (with or without suffusion) followed by piping, (3) backward erosion or sloughing (surface instability). Physical models help to understand the conditions and the physical situations in which each of these three modes of failure apply. This paper relates to these physical tests and presents the main results and conclusions

Statistical modelling of financial crashes: Rapid growth, illusion of certainty and contagion

We develop a rational expectations model of financial bubbles and study ways in which a generic risk-return interplay is incorporated into prices. We retain the interpretation of the leading Johansen-Ledoit-Sornette model, namely, that the price must rise prior to a crash in order to compensate a representative investor for the level of risk. This is accompanied, in our stochastic model, by an illusion of certainty as described by a decreasing volatility function. The basic model is then extended to incorporate multivariate bubbles and contagion, non-Gaussian models and models based on stochastic volatility. Only in a stochastic volatility model where the mean of the log-returns is fixed does volatility increase prior to a crash.financial crashes; super-exponential growth; illusion of certainty; contagion

Bubbles and crashes in finance: A phase transition from random to deterministic behaviour in prices.

We develop a rational expectations model of financial bubbles and study ways in which a generic risk-return interplay is incorporated into prices. We retain the interpretation of the leading Johansen-Ledoit-Sornette model, namely, that the price must rise prior to a crash in order to compensate a representative investor for the level of risk. This is accompanied, in our stochastic model, by an illusion of certainty as described by a decreasing volatility function. As the volatility function goes to zero, crashes can be seen to represent a phase transition from stochastic to deterministic behaviour in prices.financial crashes; super-exponential growth; illusion of certainty; housing-bubble

Bubbles and contagion in English house prices

Using methods originating from statistical physics we model bubbles in English house prices. It is found that there was a nationwide housing bubble 2002-2007. Typically prices were 30-40% over-valued and fell around 20%. London is atypical in that the level of over-pricing was lower, only around 20%, and experienced a drop in prices of only around 15%. There is some suggestion of contagious effects, with the bubble in London affecting prices in Yorkshire and the North.financial crashes; super-exponential growth; illusion of certainty; contagion; housing-bubble; Enlish house prices

Redshift distortions of galaxy correlation functions

To examine how peculiar velocities can affect the 2-, 3-, and 4-point redshift correlation functions, we evaluate volume-average correlations for configurations that emphasize and minimize redshift distortions for four different volume-limited samples from each of the CfA, SSRS, and IRAS redshift catalogs. We find a characteristic distortion for the 2-point correlation, \xibar_2: the slope $\gamma$ is flatter and the correlation length is larger in redshift space than in real space; that is, redshift distortions ``move'' correlations from small to large scales. At the largest scales (up to 12 \Mpc), the extra power in the redshift distribution is compatible with $\Omega^{4/7}/b \approx 1$. We estimate $\Omega^{4/7}/b$ to be $0.53 \pm 0.15$, $1.10 \pm 0.16$ and $0.84 \pm 0.45$ for the CfA, SSRS and IRAS catalogs. Higher order correlations \xibar_3 and \xibar_4 suffer similar redshift distortions, but in such a way that, within the accuracy of our analysis, the normalized amplitudes $S_3$ and $S_4$ are insensitive to this effect. The hierarchical amplitudes $S_3$ and $S_4$ are constant as a function of scale between 1--12 \Mpc and have similar values in all samples and catalogues, $S_3 \approx 2$ and $S_4 \approx 6$, despite the fact that \xibar_2, \xibar_3, and \xibar_4 differ from one sample to another by large factors (up to a factor of 4 in \xibar_2, 8 for \xibar_3, and 12 for \xibar_4). The agreement between the independent estimations of $S_3$ and $S_4$Comment: 20 pages (12 figues available on request), LaTeX, FERMILAB-Pub-93-097-

Void Statistics and Hierarchical Scaling in the Halo Model

We study scaling behaviour of statistics of voids in the context of the halo model of nonlinear large-scale structure. The halo model allows us to understand why the observed galaxy void probability obeys hierarchical scaling, even though the premise from which the scaling is derived is not satisfied. We argue that the commonly observed negative binomial scaling is not fundamental, but merely the result of the specific values of bias and number density for typical galaxies. The model implies quantitative relations between void statistics measured for two populations of galaxies, such as SDSS red and blue galaxies, and their number density and bias.Comment: 11 pages, 11 figures, accepted for publication in MNRA

Measurement of the B0-anti-B0-Oscillation Frequency with Inclusive Dilepton Events

The $B^0$-$\bar B^0$ oscillation frequency has been measured with a sample of 23 million \B\bar B pairs collected with the BABAR detector at the PEP-II asymmetric B Factory at SLAC. In this sample, we select events in which both B mesons decay semileptonically and use the charge of the leptons to identify the flavor of each B meson. A simultaneous fit to the decay time difference distributions for opposite- and same-sign dilepton events gives $\Delta m_d = 0.493 \pm 0.012{(stat)}\pm 0.009{(syst)}$ ps$^{-1}$.Comment: 7 pages, 1 figure, submitted to Physical Review Letter

First Observation of PP-odd γ\gamma Asymmetry in Polarized Neutron Capture on Hydrogen

We report the first observation of the parity-violating 2.2 MeV gamma-ray asymmetry $A^{np}_\gamma$ in neutron-proton capture using polarized cold neutrons incident on a liquid parahydrogen target at the Spallation Neutron Source at Oak Ridge National Laboratory. $A^{np}_\gamma$ isolates the $\Delta I=1$, \mbox{$^{3}S_{1}\rightarrow {^{3}P_{1}}$} component of the weak nucleon-nucleon interaction, which is dominated by pion exchange and can be directly related to a single coupling constant in either the DDH meson exchange model or pionless EFT. We measured $A^{np}_\gamma = [-3.0 \pm 1.4 (stat) \pm 0.2 (sys)]\times 10^{-8}$, which implies a DDH weak $\pi NN$ coupling of $h_{\pi}^{1} = [2.6 \pm 1.2(stat) \pm 0.2(sys)] \times 10^{-7}$ and a pionless EFT constant of $C^{^{3}S_{1}\rightarrow ^{3}P_{1}}/C_{0}=[-7.4 \pm 3.5 (stat) \pm 0.5 (sys)] \times 10^{-11}$ MeV$^{-1}$. We describe the experiment, data analysis, systematic uncertainties, and the implications of the result.Comment: 6 pages, 5 figure

Prospects for K+→π+ννˉK^+ \to \pi^+ \nu \bar{ \nu } at CERN in NA62

The NA62 experiment will begin taking data in 2015. Its primary purpose is a 10% measurement of the branching ratio of the ultrarare kaon decay $K^+ \to \pi^+ \nu \bar{ \nu }$, using the decay in flight of kaons in an unseparated beam with momentum 75 GeV/c.The detector and analysis technique are described here.Comment: 8 pages for proceedings of 50 Years of CP