Bioerosive structures of sclerozoan foraminifera from the lower pliocene of southern Spain: a contribution to the palaeoecology of marine hard substrate communities

A palaeoecological study of sclerozoan foraminifera of the families Saccamminidae (aff. Sagenina), Lituolidae (Placopsilina), Cibicididae (Cibicides, Dyocibicides, Cibicidella) and Planorbulinidae (Planorbulina and Planorbulinella) that colonized epifaunal bivalves (ostreids and pectinids) during the early Pliocene in southern Spain has led to the recognition of two new boring ichnogenera: Camarichnus ichnogen. nov., with two ichnospecies, C. subrectangularis ichnosp. nov. and C. arcuatus ichnosp. nov., and Canalichnus ichnogen. nov., with one ichnospecies, C. tenuis ichnosp. nov. The first two ichnospecies were produced by adnate lituolids and cibicidids, the last by saccamminids. Their recognition is very important when quantifying populations of these organisms. Colonisation took place after death of the host bivalves, when they acted as very stable substrates whose topography probably controlled the initial settlement pattern of the foraminifera. The colonisation sequence started with the foraminifera (lituolids-saccamminids-cibicidids-planorbulinids) and was followed by vermetid gastropods, serpulids, spirorbids, cheilostome bryozoans and/or ostreids. Preferred orientations and over-growth relationships between cheilostome bryozoans and serpulids have been detected in this material.info:eu-repo/semantics/publishedVersio

Two stories outside Boltzmann-Gibbs statistics: Mori's q-phase transitions and glassy dynamics at the onset of chaos

First, we analyze trajectories inside the Feigenbaum attractor and obtain the atypical weak sensitivity to initial conditions and loss of information associated to their dynamics. We identify the Mori singularities in its Lyapunov spectrum with the appearance of a special value for the entropic index q of the Tsallis statistics. Secondly, the dynamics of iterates at the noise-perturbed transition to chaos is shown to exhibit the characteristic elements of the glass transition, e.g. two-step relaxation, aging, subdiffusion and arrest. The properties of the bifurcation gap induced by the noise are seen to be comparable to those of a supercooled liquid above a glass transition temperature.Comment: Proceedings of: 31st Workshop of the International School of Solid State Physics, Complexity, Metastability and Nonextensivity, Erice (Sicily) 20-26 July 2004 World Scientific in the special series of the E. Majorana conferences, in pres

"Government Contained?" Explaining Spanish Supreme Court's decisions on EU law

The question of why and when European Law is enforced by national courts may be one of the most important questions that scholars on the European Union seek to answer. Citizens and other social and economic actors turn to courts as an instrument of enforcement when implementation problems of EU law occur in their countries. The main aim of this work is to understand the main mechanisms behind the judicial enforcement of EU law, looking for this purpose at the diverse elements that play a part during the judicial decision-making of the Spanish Supreme Court, which judgments may shape the impact of EU regulation on national policies. The study finds to what extent high courts are concerned about the reaction of the authorities. Moreover, the results show how the courts cite ECJ to support their decisions where the EU law challenges the main principles and prerogatives of the national authorities

Tsallis' q index and Mori's q phase transitions at edge of chaos

We uncover the basis for the validity of the Tsallis statistics at the onset of chaos in logistic maps. The dynamics within the critical attractor is found to consist of an infinite family of Mori's $q$-phase transitions of rapidly decreasing strength, each associated to a discontinuity in Feigenbaum's trajectory scaling function $\sigma$. The value of $q$ at each transition corresponds to the same special value for the entropic index $q$, such that the resultant sets of $q$-Lyapunov coefficients are equal to the Tsallis rates of entropy evolution.Comment: Significantly enlarged version, additional figures and references. To be published in Physical Review

Paleoecología de la malacofauna de bivalvos del Mioceno superior de Cacela (SE Portugal)

El interés por el yacimiento fósil de la Ribera de Cacela (SE Portugal) se remonta al siglo pasado y se centra principalmente en la gran riqueza y diversidad de la fauna malacológica, siendo de destacar el excelente estado de conservación que éstas presentan. Del estudio realizado, tomando como base la malacofauna de bivalvos, se han podido identificar un total de 85 especies y subespecies. El estudio tafonómico se realizó teniendo en cuenta la litología, la composición de los bivalvos, la bioerosión y la presencia de otros taxa, que pudieran aportar, eventualmente, datos importantes que completaran este apartado. El estudio de la paleocomunidad de bivalvos desde un punto de vista paleoambiental, para el área de estudio, sugiere un medio marino litoral de energía baja a moderada y una profundidad estimada entre 20 y 30 metros; una salinidad semejante a la actual dentro de un régimen térmico tropical a subtropical y temperatura del agua superior a las observadas actualmente para estas latitudes. Palabras clave: Bivalvia, Paleoecología, Tortoniense superior, Cacela, SE Portugal.The interest for the Ribeira de Cacela fossil outcrop (SE Portugal) dating back to the mid-nineteenth century and was focused by the presence of a rich and diverse fauna, especially invertebrates, in an excellent state of preservation. In base on the study of bivalve malacofaune a total of 85 species and subspecies were identified. The paleoecologic analysis was done covering lithologic aspects, bivalve faune composition, bioerosion and presence of other taxa, which give relevant data to complete this subject. The local environmental conditions suggested by the bivalve assemblage indicate the presence of a coastal environmental, with low to moderate hydrodynamic conditions, depths around 20 to 30 meters, salinity conditions similar to the present ones and tropical to subtropical thermal regime, with higher water temperatures than those observed presently at these latitudes. Key words: Bivalvia, Paleoecology, Upper Tortonian, Cacela, SE Portugal.El interés por el yacimiento fósil de la Ribera de Cacela (SE Portugal) se remonta al siglo pasado y se centra principalmente en la gran riqueza y diversidad de la fauna malacológica, siendo de destacar el excelente estado de conservación que éstas presentan. Del estudio realizado, tomando como base la malacofauna de bivalvos, se han podido identificar un total de 85 especies y subespecies. El estudio tafonómico se realizó teniendo en cuenta la litología, la composición de los bivalvos, la bioerosión y la presencia de otros taxa, que pudieran aportar, eventualmente, datos importantes que completaran este apartado. El estudio de la paleocomunidad de bivalvos desde un punto de vista paleoambiental, para el área de estudio, sugiere un medio marino litoral de energía baja a moderada y una profundidad estimada entre 20 y 30 metros; una salinidad semejante a la actual dentro de un régimen térmico tropical a subtropical y temperatura del agua superior a las observadas actualmente para estas latitudes. Palabras clave: Bivalvia, Paleoecología, Tortoniense superior, Cacela, SE Portugal

Scaling and dynamics of turbulence over sparseA canopies

Turbulent flows within and over sparse canopies are investigated using direct numerical simulations. We focus on the effect of the canopy on the background turbulence, the part of the flow that remains once the element-induced flow is filtered out. In channel flows, the distribution of the total stress is linear with height. Over smooth walls, the total stress is only the `fluid stress' $\tau_f$, the sum of the viscous and the Reynolds shear stresses. In canopies, in turn, there is an additional contribution from the canopy drag, which can dominate within. We find that, for sparse canopies, the ratio of the viscous and the Reynolds shear stresses in $\tau_f$ at each height is similar to that over smooth-walls, even within the canopy. From this, a height-dependent scaling based on $\tau_f$ is proposed. Using this scaling, the background turbulence within the canopy shows similarities with turbulence over smooth walls. This suggests that the background turbulence scales with $\tau_f$, rather than with the conventional scaling based on the total stress. This effect is essentially captured when the canopy is substituted by a drag force that acts on the mean velocity profile alone, aiming to produce the correct $\tau_f$, without the discrete presence of the canopy elements acting directly on the fluctuations. The proposed mean-only forcing is shown to produce better estimates for the turbulent fluctuations compared to a conventional, homogeneous-drag model. The present results thus suggest that a sparse canopy acts on the background turbulence primarily through the change it induces on the mean velocity profile, which in turn sets the scale for turbulence, rather than through a direct interaction of the canopy elements with the fluctuations. The effect of the element-induced flow, however, requires the representation of the individual canopy elements.Cambridge Commonwealth, European and International Trust PRACE DECI-15 European Research Counci

Turbulent flows over dense filament canopies

Turbulent flows over dense canopies of rigid filaments of small size are investigated for different element heights and spacings using DNS. The flow can be decomposed into the element-coherent, dispersive flow, the Kelvin--Helmholtz-like rollers typically reported over dense canopies, and the background, incoherent turbulence. The canopies studied have spacings $s^+ = 3$--$50$, which essentially preclude the background turbulence from penetrating within. The dispersive velocity fluctuations are also mainly determined by the spacing, and are small deep within the canopy, where the footprint of the Kelvin--Helmholtz-like rollers dominates. Their typical streamwise wavelength is determined by the mixing length, which is essentially the sum of its height above and below the canopy tips. For the present dense canopies, the former remains roughly the same in wall-units, and the latter, which scales with the drag length, depends linearly on the spacing. This is the result of the drag being essentially viscous and governed by the planar layout of the canopy. In shallow canopies, the proximity of the canopy floor inhibits the formation of Kelvin--Helmholtz-like rollers, with essentially no signature for height-to-spacing ratios $h/s \approx 1$, and no further inhibition beyond $h/s \approx 6$. Very small spacings also inhibit the rollers, due to their obstruction by the canopy elements. The obstruction decreases with increasing spacing and the signature of the instability intensifies, even if for canopies sparser than those studied here the instability eventually breaks down. Simple models based on linear stability can capture some of the above effects.Cambridge Commonwealth, European and International Trust EPSRC Tier-2 grant EP/P020259/

Multifractality and nonextensivity at the edge of chaos of unimodal maps

We examine both the dynamical and the multifractal properties at the chaos threshold of logistic maps with general nonlinearity $z>1$. First we determine analytically the sensitivity to initial conditions $\xi_{t}$. Then we consider a renormalization group (RG) operation on the partition function $Z$ of the multifractal attractor that eliminates one half of the multifractal points each time it is applied. Invariance of $Z$ fixes a length-scale transformation factor $2^{-\eta}$ in terms of the generalized dimensions $D_{\beta}$. There exists a gap $\Delta \eta$ in the values of $\eta$ equal to $\lambda _{q}=1/(1-q)=D_{\infty}^{-1}-D_{-\infty}^{-1}$ where $\lambda_{q}$ is the $q$-generalized Lyapunov exponent and $q$ is the nonextensive entropic index. We provide an interpretation for this relationship - previously derived by Lyra and Tsallis - between dynamical and geometrical properties. Key Words: Edge of chaos, multifractal attractor, nonextensivityComment: Contribution to the proceedings of 2nd International Conference on News and Expectations in Thermostatistics (NEXT03), Cagliari, Italy, 21-28/09/2003. Submitted to Physica