Coseismic horizontal slip revealed by sheared clastic dikes in the Dead Sea Basin

Peer reviewedPostprin

Expanding perfect fluid generalizations of the C-metric

We reexamine Petrov type D gravitational fields generated by a perfect fluid with spatially homogeneous energy density and in which the flow lines form a timelike non-shearing and non-rotating congruence. It is shown that the anisotropic such spacetimes, which comprise the vacuum C-metric as a limit case, can have \emph{non-zero} expansion, contrary to the conclusion in the original investigation by Barnes (Gen. Rel. Grav. 4, 105 (1973)). This class consists of cosmological models with generically one and at most two Killing vectors. We construct their line element and discuss some important properties. The methods used in this investigation incite to deduce testable criteria regarding shearfree normality and staticity op Petrov type $D$ spacetimes in general, which we add in an appendix.Comment: 16 pages, extended and amended versio

A very low temperature STM for the local spectroscopy of mesoscopic structures

We present the design and operation of a very-low temperature Scanning Tunneling Microscope (STM) working at $60 mK$ in a dilution refrigerator. The STM features both atomic resolution and micron-sized scanning range at low temperature. This work is the first experimental realization of a local spectroscopy of mesoscopic structures at very low temperature. We present high-resolution current-voltage characteristics of tunnel contacts and the deduced local density of states of hybrid Superconductor-Normal metal systems.Comment: 5 pages, 5 figures, slightly corrected versio

A discrete linearizability test based on multiscale analysis

In this paper we consider the classification of dispersive linearizable partial difference equations defined on a quad-graph by the multiple scale reduction around their harmonic solution. We show that the A1, A2 and A3 linearizability conditions restrain the number of the parameters which enter into the equation. A subclass of the equations which pass the A3 C-integrability conditions can be linearized by a Möbius transformation

On the Integrability of the Discrete Nonlinear Schroedinger Equation

In this letter we present an analytic evidence of the non-integrability of the discrete nonlinear Schroedinger equation, a well-known discrete evolution equation which has been obtained in various contexts of physics and biology. We use a reductive perturbation technique to show an obstruction to its integrability.Comment: 4 pages, accepted in EP

Multiscale reduction of discrete nonlinear Schroedinger equations

We use a discrete multiscale analysis to study the asymptotic integrability of differential-difference equations. In particular, we show that multiscale perturbation techniques provide an analytic tool to derive necessary integrability conditions for two well-known discretizations of the nonlinear Schroedinger equation.Comment: 12 page

Integrability of Differential-Difference Equations with Discrete Kinks

In this article we discuss a series of models introduced by Barashenkov, Oxtoby and Pelinovsky to describe some discrete approximations to the \phi^4 theory which preserve travelling kink solutions. We show, by applying the multiple scale test that they have some integrability properties as they pass the A_1 and A_2 conditions. However they are not integrable as they fail the A_3 conditions.Comment: submitted to the Proceedings of the workshop "Nonlinear Physics: Theory and Experiment.VI" in a special issue di Theoretical and Mathematical Physic

Biodegradable dissolved organic carbon removal during biological filtration on granular actived carbon

En production d'eau potable, la nature bactérienne de l'abattement du carbone organique dissous biodégradable (CODB) observé dans les filtres à charbon actif en grains (CAG) a été démontrée. Les performances de fonctionnement de ce type de contacteur biologique ont été principalement étudiées sur pilotes. Dans la présente étude, elles sont vérifiées et transposées en condition d'exploitation sur une usine de production d'eau potable de la. banlieue parisienne. La colonisation bactérienne du CAG a été suivie et montre que l'équilibre biologique est atteint après filtration d'environ 12500m3 d'eau/m3 de CAG. Durant cette phase de colonisation, la biodégradation se substitue progressivement à l'adsorption pour abattre le COD. Après colonisation, l'efficacité des filtres biologiques, exprimée en terme d'abattement de CODB, est fonction du temps de contact quelle que soit la vitesse de filtration (dans la gamme de 2 à 18 m/h). Les résultats de suivis de deux filtres sur deux ans montrent que l'efficacité a été globalement meilleure en 1989 qu'en 1990, cette différence s'explique par les fluctuations plus importantes de CODB dans l'influent en 1989. Un modèle mathématique, établi à partir des équations cinétiques des processus bactériens dans les filtres à CAG (modèle CHABROL), développé sur base d'observations antérieures, permet de simuler correctement les observations faites au cours de la présente étude. Avec la mesure du CODB, le modèle CHABROL constitue un outil très bien adapté pour contrôler les performances des contacteurs biologiques. Ils permettent, entre autre, de définir le temps de contact optimal de l'eau dans le filtre en fonction d'une température et d'une qualité d'eau donnée dans l'influent et d'une qualité d'eau souhaitée dans l'effluent.In drinking water production, filtration on granular activated carton (GAC) is generally used in order to remove by adsorption the dissolved organic matter. Nevertheless, the adsorption capacity of GAC is rapidly saturated and it is so necessary to regenerate the GAC. An interesting alternate has been applied in some treatment plants. It consists to use GAC filtration without regeneration taking benefit of the activity of the microbial community which colonize the GAC particles (RITTMAN and HUCK, 1989). In fact, this biological filtration offers the advantage to specially remove the biodegradable fraction of the dissolved organic carbon (BDOC), which is responsible for the problem of bacterial growth into the distribution networks.The bacterial nature of the BDOC removal achieved by the biological filtration on GAC has been now clearly demonstrated (SERVAIS et al., 1991) and some important results of the functioning of these filters has been obtained in studies conducted on pilots filters (BOUILLOT et al., 1990; SERVAIS et al., 1992). These studies have for example shown that only a very small part of the bacterial biomass produced in the filter is exported with the outflow.In the present study, biological filtration has been investigated in a full scale treatment line at Choisy-le-Roi in the Parisian suburbs and the results compared with those gained on pilot filters.The working conditions of the three GAC filter studied are presented in table 1 and compared with those of pilot filters used in a previous study conducted al Neuilly-sur-Marne (table 2). The microbial colonization has been followed in two of the liners. If lasted roughly 3 months to reach biological equilibration, it corresponds to a water volume filtrated of 12 500 m3 per m3 of GAC. Efficiency of the removal during this period is presented in figure 2. Progressively, biological processes take turn with adsorption (fig. 1).As already demonstrated by SERVAIS et al. (1992), the efficiency of biological filtration, calculated in percentage of BDOC removal, increases with increasing contact time whatever the filtration velocity could be in the range 2 m/h to 18 m/h (fig. 3). However, the percentage of BDOC, at similar temperature, is higher in the GAC filters at Choisy-le-Roi than at Neuilly-sur-Marne. The fixed bacterial biomass is also higher at Choisy-le-Roi (average 7.5 µgC/cm3) than at Neuilly-sur-Marne (average 2 µC/cm3).Following during two years the functioning of the n° 56 and 38 filters (tables 3, 4 and fig. 5, 7), it seems that the global efficiency of filtration is better in 1990 than in 1989. This can be linked to the greater fluctuations in BDOC in the influent water in 1989 than in 1990, as shown on figure 8. Fluctuations in the quality of the influent water requires a period to reach the equilibrium during which the effluent is charchacterized by a lower quality (fig. 8). This period is longer at low temperature. The mathematical modal based on the kinetics of the basic microbiological processes involved in biological filtration (the CHABROL model) has been previously developed (BILLEN et al., 1992) in order la simulate the performances of the filtration. It can be used to simulate the vertical profiles of BDOC and bacterial biomass in the filters of the Choisy-le-Roi treatment plant, with modifying only one parameter in the model, the average bacterial mortality “kd” (fig. 4). BDOC decreases versus empty bed contact time (EBCT) calculated by the modal are presented on figure 6 for the Choisy-le-Roi and Neuilly-sur-Marne treatment plants and for two temperatures.From a management point of view, the minimum BDOC is reached for contact time between 15 and 20 minutes at Neuilly-sur-Marne, while at Choisy-le-Roi it is rather between 10 and 15 minutes.In conclusion, BDOC measurements and CHABROL modal constitute powerful tools for management and design of biological GAC filters

Continuous Symmetries of Difference Equations

Lie group theory was originally created more than 100 years ago as a tool for solving ordinary and partial differential equations. In this article we review the results of a much more recent program: the use of Lie groups to study difference equations. We show that the mismatch between continuous symmetries and discrete equations can be resolved in at least two manners. One is to use generalized symmetries acting on solutions of difference equations, but leaving the lattice invariant. The other is to restrict to point symmetries, but to allow them to also transform the lattice.Comment: Review articl

Progress in High Resolution Scanning Ion Microscopy and Secondary Ion Mass Spectrometry Imaging Microanalysis

The performance of a new high resolution scanning ion microprobe (SIM) is elucidated with regard to imaging capabilities using the ion-induced secondary electron (ISE) or secondary ion (ISI) signals, and the mass-resolved signal from a secondary ion mass spectrometry (SIMS) system. The new instrument focuses a beam extracted from a liquid metal ion source (LMIS) to a range of spot sizes reaching the 20 nm level. The probe current (1.6 pA) available at this level of lateral resolution, which approaches the theoretical resolution limits of the SIMS method, is still adequate to obtain detailed isotopic maps for surfaces rich in the elements of low ionization potential (positive ISI), or high electron affinity (negative ISI). In addition to examples of high resolution ISE and ISI images of objects displaying sufficiently small topographic detail, mass spectra and isotopic maps are shown, testing both the lateral and depth resolution attained. The latter results belong with a program of interdisciplinary research applications of the new microprobe, which include studies of e.g., the monolayer lateral distribution of intercalant in SbCl5 intercalated graphite and of silicate minerals and iron distribution in sections of chondrules and their rims (components of chondrites, a class of stoney meteorites). In the biomedical field, the new microprobe finds application in e.g., the study of human renal calculi and bone. Most promising is the use of stable isotope tracers (e.g., Ca44) to unravel the dynamics of bone mineralization, as thus far shown with the in-vitro culture of the skull bone of neonatal mice