Multifractality and intermediate statistics in quantum maps

We study multifractal properties of wave functions for a one-parameter family of quantum maps displaying the whole range of spectral statistics intermediate between integrable and chaotic statistics. We perform extensive numerical computations and provide analytical arguments showing that the generalized fractal dimensions are directly related to the parameter of the underlying classical map, and thus to other properties such as spectral statistics. Our results could be relevant for Anderson and quantum Hall transitions, where wave functions also show multifractality.Comment: 4 pages, 4 figure

Anticoherence of spin states with point group symmetries

We investigate multiqubit permutation-symmetric states with maximal entropy of entanglement. Such states can be viewed as particular spin states, namely anticoherent spin states. Using the Majorana representation of spin states in terms of points on the unit sphere, we analyze the consequences of a point-group symmetry in their arrangement on the quantum properties of the corresponding state. We focus on the identification of anticoherent states (for which all reduced density matrices in the symmetric subspace are maximally mixed) associated with point-group symmetric sets of points. We provide three different characterizations of anticoherence, and establish a link between point symmetries, anticoherence and classes of states equivalent through stochastic local operations with classical communication (SLOCC). We then investigate in detail the case of small numbers of qubits, and construct infinite families of anticoherent states with point-group symmetry of their Majorana points, showing that anticoherent states do exist to arbitrary order.Comment: 15 pages, 5 figure

Antisymmetrization of a Mean Field Calculation of the T-Matrix

The usual definition of the prior(post) interaction $V(V^\prime )$ between projectile and target (resp. ejectile and residual target) being contradictory with full antisymmetrization between nucleons, an explicit antisymmetrization projector ${\cal A}$ must be included in the definition of the transition operator, $T\equiv V^\prime{\cal A}+V^\prime{\cal A}GV.$ We derive the suitably antisymmetrized mean field equations leading to a non perturbative estimate of $T$. The theory is illustrated by a calculation of forward $\alpha$-$\alpha$ scattering, making use of self consistent symmetries.Comment: 30 pages, no figures, plain TeX, SPHT/93/14

Phenomenological discussion of B→PVB\to P V decays in QCD improved factorization approach

Trying a global fit of the experimental branching ratios and CP-asymmetries of the charmless $B\to PV$ decays according to QCD factorization, we find it impossible to reach a satisfactory agreement, the confidence level (CL) of the best fit is smaller than .1 %. This failure reflects the difficulty to accommodate several large experimental branching ratios of the strange channels. Furthermore, experiment was not able to exclude a large direct CP asymmetry in $\bar {B}^0\to\rho^+ \pi^-$, which is predicted very small by QCD factorization. Proposing a fit with QCD factorization complemented by a charming-penguin inspired model we reach a best fit which is not excluded by experiment (CL of about 8 %) but is not fully convincing. These negative results must be tempered by the remark that some of the experimental data used are recent and might still evolve significantly.Comment: 8 pages, 2 figures (requires epsfig, psfrag),talk presented at the XXXVIIIth Rencontres de Moriond: Electroweak Interactions and Unified Theories,Les Arcs, France, March 15-22, 2003. To be published in the Proceeding

Entanglement and localization of wavefunctions

We review recent works that relate entanglement of random vectors to their localization properties. In particular, the linear entropy is related by a simple expression to the inverse participation ratio, while next orders of the entropy of entanglement contain information about e.g. the multifractal exponents. Numerical simulations show that these results can account for the entanglement present in wavefunctions of physical systems.Comment: 6 pages, 4 figures, to appear in the proceedings of the NATO Advanced Research Workshop 'Recent Advances in Nonlinear Dynamics and Complex System Physics', Tashkent, Uzbekistan, 200

Cystic Fibrosis and moulds: updates from the last meeting of the working group

International audienc

Bilan hydrologique d'un marais littoral à vocation agricole : Le marais de Moëze (Charente-Maritime, France)

En France, les sécheresses consécutives des années 1985, 1986, 1989 et 1990 ont mis en lumière les problèmes relatifs à l'alimentation en eau potable, l'irrigation des terres agricoles et la préservation des écosystèmes aquatiques. Dans le cas des zones humides, continentales et littorales, caractérisées par une compartimentation hydraulique souvent complexe, le manque de connaissance se fait particulièrement sentir. Bien que de nombreux travaux aient permis d'évaluer l'évaporation des masses d'eau et l'évapotranspiration de certaines espèces d'hydrophytes et d'hélophytes, les études débouchant sur des bilans quantitatifs restent peu fréquentes. Le bilan hydrologique du marais de Moëze (2250 ha) a été calculé par décade entre le 11/06/89 et le 31/08/89. Il prend en compte le débit au droit de l'ouvrage d'alimentation, les volumes prélevés pour l'irrigation hors marais, les infiltrations et l'évapotransplration sur les 318 km de canaux. L'estimation de la consommation d'eau des parcelles est globalisée au niveau des mesures d'infiltration.Les pertes par infiltration sont secondaires (9,4 %) au regard des volumes prélevés pour l'irrigation (38,0 %) et évapotransplrés par les canaux (43,7 %) dont 51,1 % uniquement par les 28,6 % des plans d'eau colonisés par Typha latifolia.L'optimisation de la gestion estivale de l'eau d'un marais littoral agricole nécessite dans un premier temps de minimiser les pertes. C'est essentiellement sur la consommation d'eau des canaux colonisés par les hélophytes que l'on peut intervenir. Nous proposons un abaque qui permet d'évaluer l'importance des économies d'eau réalisées en fonction de plusieurs scénarios d'aménagement du réseau hydraulique.In France, the drought that occurred during the years 1985, 1986, 1989 and 1990 have emphazised the problems of freshwater supplies for human consumption, for irrigation and for the conservation of aquatic systems. Today the water has to be economized through a rationalized management. Water balance must be evaluated in order to compare supply an demand. Hydrological functioning is particularly badly known as far as continental and coastal wetlands are concerned, probably because of a generally very complex hydrological partition. Many papers deal with the evaporation rate from a clear water surface or the evapotranspiration rate from several species of hydrophytes and halophytes. However studies of quantitative water budgets of wetlands remain few in number.This paper reports an analysis of the budget summer water in that was a salt marsh now containing freshwater. The 25 km2 marsh of Moëze is located on the French Atlantic coast; it has been progressively constituted by filling up a tidal bay since the flandrien period. The soils correspond to fluvio-marine silts, locally called « bri » accumulated over several tens of meters thick. The marsh is bounded on the North by the ancient limestone coast, on the South by the Arnoult River, and on the West by the coastline. Its drainage network includes permanently flowing main canals and also small silted-up ditches which sometimes dry up in summer and are largely colonized by aquatic plants, particularly Typha latifolia. The channels network is very dense (144 meters of ditches per hectare) and complex because of a close connection between all the canals and ditches. The regional oceanic climate is characterized by a surplus water balance from October to April (+ 315 mm) and quite a short one tram May to September (-338 mm).The important terms of the water budget equation in this study were : the quantity of water pumped from the Arnoult River through the inflow sluicegate (Qa), the precipitations (P), the irrigation out of the marsh (lr), the evapotranspiration of water bodies (Epo), the seepage through canals and ditches (ls), and the change in water soil strorage (Vs). These terms are not equally susceptible to be measured. Groundwater seepage and evapotranspiration are difficult to measure and they are often determined by difference, but, they contain the residual error of ail the terms. The methods to evaluate each term of water budget were carried as follows :1. As the inflow gate functions as a siphon, the flow rate (Qa) was calculated with the drowned orifice formula (LENCASTRE, 1984). The upstream and downstream water levels were permanently recorded by 2 limnigraphs. The upstream and downstream water velocities were measured every 2 days with a micro-currentmeter.2. The precipitation values (P) used in the water budget equation correspond to the average of 4 rain gauges placed around the marsh.3. The evapotranspiration of the channel network (Epo) was directly estimated through 4 experimental floating tanks (0.50 x 0.55 x 1.05 m size) previously used by GIRAUD (1985). One of the tanks was placed in clear water, the others was planted the typical aquatic vegetation of the marsh (Lemna sp., Ceratophyllum sp., and Typhia latifolia). The drop the water levels in the tanks corresponded to the loss of water due tou evapotranspiration. All the tanks were filled up to a fixed level, and the amount of water added, measured every 2 days.4. The outputs for irrigation (Ir) concern 298 ha of maïze out of the marsh, and 23 farmers. The water amounts taken off were estimated form an inquiry of irrigation practices associated to a field control.5. The water losses by seepage (ls) through canals and ditches were directly measured on the field by using the closed basin method. A length of canal was closed by 2 watertight bulkheads. The fall of water level was recorded and the amount of water added to maintain a fixed level was measured. This method is considered by KRAATZ (1977) as being the most accurate specially for low seepage. The fall of water level never exceeds 10 % of the water depth in the basin. 34 canals and ditches in the marsh were sampled. According to CHEVALLIER et al. (1984), 3 parameters influencing the soil permeability were measured : granulometry, CaC03 content and sodicity. After the sampling plan we have retained 4 experimental canals (average length =47 m, average water surface = 135 m2, average depth = 0.44 m).6. The water strorage in the soil (Vs) was evaluated by analyzing the groundwater table fluctuations and moisture changes.The water budget calculated for 10-day periods depending on the climatology calculations, from 10th June 1989 to 31st August 1989. The water losses due to seepage were secondary (9.4 %) compared to the amounts of water taken off by irrigation (38.0 %) and channel network evapotranspiration (43.7 %). The water consumption of helophytes such as Typhia latifolia was 2 to 3 times higher than the evaporation of a clear surface water body as shown in figure 3. In the marsh of Moëze, 51.1 % of channel evapotranspiration was due to the colonization by Typhia latifolia of the canals and ditches although they represent only 28.6 % of the channel network surface.This study shows that is possible to quantify a water budget for a large scale wetland from field measurements associated to experimental approaches, with a satisfactory accuracy : less than 10 %. To reduce the water consumption of the marsh of Moëze, three essential recommendations may be given : the reduction of the global channel network surface, the cleaning of a part of ditches colonized by Typhia latifolia, or the combination of both techniques. According to the different management schemes, it is possible to predict the amounts of freshwater saved (fig. 5)

Bilan hydrologique d'un marais littoral à vocation agricole : Le marais de Moëze (Charente-Maritime, France)

En France, les sécheresses consécutives des années 1985, 1986, 1989 et 1990 ont mis en lumière les problèmes relatifs à l'alimentation en eau potable, l'irrigation des terres agricoles et la préservation des écosystèmes aquatiques. Dans le cas des zones humides, continentales et littorales, caractérisées par une compartimentation hydraulique souvent complexe, le manque de connaissance se fait particulièrement sentir. Bien que de nombreux travaux aient permis d'évaluer l'évaporation des masses d'eau et l'évapotranspiration de certaines espèces d'hydrophytes et d'hélophytes, les études débouchant sur des bilans quantitatifs restent peu fréquentes. Le bilan hydrologique du marais de Moëze (2250 ha) a été calculé par décade entre le 11/06/89 et le 31/08/89. Il prend en compte le débit au droit de l'ouvrage d'alimentation, les volumes prélevés pour l'irrigation hors marais, les infiltrations et l'évapotransplration sur les 318 km de canaux. L'estimation de la consommation d'eau des parcelles est globalisée au niveau des mesures d'infiltration.Les pertes par infiltration sont secondaires (9,4 %) au regard des volumes prélevés pour l'irrigation (38,0 %) et évapotransplrés par les canaux (43,7 %) dont 51,1 % uniquement par les 28,6 % des plans d'eau colonisés par Typha latifolia.L'optimisation de la gestion estivale de l'eau d'un marais littoral agricole nécessite dans un premier temps de minimiser les pertes. C'est essentiellement sur la consommation d'eau des canaux colonisés par les hélophytes que l'on peut intervenir. Nous proposons un abaque qui permet d'évaluer l'importance des économies d'eau réalisées en fonction de plusieurs scénarios d'aménagement du réseau hydraulique.In France, the drought that occurred during the years 1985, 1986, 1989 and 1990 have emphazised the problems of freshwater supplies for human consumption, for irrigation and for the conservation of aquatic systems. Today the water has to be economized through a rationalized management. Water balance must be evaluated in order to compare supply an demand. Hydrological functioning is particularly badly known as far as continental and coastal wetlands are concerned, probably because of a generally very complex hydrological partition. Many papers deal with the evaporation rate from a clear water surface or the evapotranspiration rate from several species of hydrophytes and halophytes. However studies of quantitative water budgets of wetlands remain few in number.This paper reports an analysis of the budget summer water in that was a salt marsh now containing freshwater. The 25 km2 marsh of Moëze is located on the French Atlantic coast; it has been progressively constituted by filling up a tidal bay since the flandrien period. The soils correspond to fluvio-marine silts, locally called « bri » accumulated over several tens of meters thick. The marsh is bounded on the North by the ancient limestone coast, on the South by the Arnoult River, and on the West by the coastline. Its drainage network includes permanently flowing main canals and also small silted-up ditches which sometimes dry up in summer and are largely colonized by aquatic plants, particularly Typha latifolia. The channels network is very dense (144 meters of ditches per hectare) and complex because of a close connection between all the canals and ditches. The regional oceanic climate is characterized by a surplus water balance from October to April (+ 315 mm) and quite a short one tram May to September (-338 mm).The important terms of the water budget equation in this study were : the quantity of water pumped from the Arnoult River through the inflow sluicegate (Qa), the precipitations (P), the irrigation out of the marsh (lr), the evapotranspiration of water bodies (Epo), the seepage through canals and ditches (ls), and the change in water soil strorage (Vs). These terms are not equally susceptible to be measured. Groundwater seepage and evapotranspiration are difficult to measure and they are often determined by difference, but, they contain the residual error of ail the terms. The methods to evaluate each term of water budget were carried as follows :1. As the inflow gate functions as a siphon, the flow rate (Qa) was calculated with the drowned orifice formula (LENCASTRE, 1984). The upstream and downstream water levels were permanently recorded by 2 limnigraphs. The upstream and downstream water velocities were measured every 2 days with a micro-currentmeter.2. The precipitation values (P) used in the water budget equation correspond to the average of 4 rain gauges placed around the marsh.3. The evapotranspiration of the channel network (Epo) was directly estimated through 4 experimental floating tanks (0.50 x 0.55 x 1.05 m size) previously used by GIRAUD (1985). One of the tanks was placed in clear water, the others was planted the typical aquatic vegetation of the marsh (Lemna sp., Ceratophyllum sp., and Typhia latifolia). The drop the water levels in the tanks corresponded to the loss of water due tou evapotranspiration. All the tanks were filled up to a fixed level, and the amount of water added, measured every 2 days.4. The outputs for irrigation (Ir) concern 298 ha of maïze out of the marsh, and 23 farmers. The water amounts taken off were estimated form an inquiry of irrigation practices associated to a field control.5. The water losses by seepage (ls) through canals and ditches were directly measured on the field by using the closed basin method. A length of canal was closed by 2 watertight bulkheads. The fall of water level was recorded and the amount of water added to maintain a fixed level was measured. This method is considered by KRAATZ (1977) as being the most accurate specially for low seepage. The fall of water level never exceeds 10 % of the water depth in the basin. 34 canals and ditches in the marsh were sampled. According to CHEVALLIER et al. (1984), 3 parameters influencing the soil permeability were measured : granulometry, CaC03 content and sodicity. After the sampling plan we have retained 4 experimental canals (average length =47 m, average water surface = 135 m2, average depth = 0.44 m).6. The water strorage in the soil (Vs) was evaluated by analyzing the groundwater table fluctuations and moisture changes.The water budget calculated for 10-day periods depending on the climatology calculations, from 10th June 1989 to 31st August 1989. The water losses due to seepage were secondary (9.4 %) compared to the amounts of water taken off by irrigation (38.0 %) and channel network evapotranspiration (43.7 %). The water consumption of helophytes such as Typhia latifolia was 2 to 3 times higher than the evaporation of a clear surface water body as shown in figure 3. In the marsh of Moëze, 51.1 % of channel evapotranspiration was due to the colonization by Typhia latifolia of the canals and ditches although they represent only 28.6 % of the channel network surface.This study shows that is possible to quantify a water budget for a large scale wetland from field measurements associated to experimental approaches, with a satisfactory accuracy : less than 10 %. To reduce the water consumption of the marsh of Moëze, three essential recommendations may be given : the reduction of the global channel network surface, the cleaning of a part of ditches colonized by Typhia latifolia, or the combination of both techniques. According to the different management schemes, it is possible to predict the amounts of freshwater saved (fig. 5)

Effective thermal conductivity of oolitic rocks using the Maxwell homogenization method

International audienceThe present work focuses on effective thermal conductivity of oolitic lime-stones, characterized by an assemblage of porous grains (oolites), mesopores and solid grains. Two distinct scales of pores, micropores or intra oolitic pores and mesopores or inter oolitic pores are taken into account. At the first step, micropores are homogenized inside the oolites by using self consistent homogenization scheme. The second homogenization step describing transition from the mesoscale to the macroscale, is performed by using a recent reformulation of the Maxwell homogenization scheme (see [1]). At the mesoscale, porous oolitic inclusions are quasi spherical whereas two families of mesopores are considered according to analysis of photomicrographs: (1) randomly oriented oblate spheroidal pores and (2) concave pores. The proposed model is compared to a simplified one when all the pores are of ellipsoidal shape. The relevancy of the ellipsoidal approximation is then evaluated. In particular, the influence of the shape of the mesopores on the overall thermal conductivity is discussed. Comparisons between multi-scale model based on Maxwell homogenization method and experimental data show that effects of porosity and saturating fluids on overall conductivity are correctly predicted when concave pores are taken into account