The rise of the diptera‐microbial mat interactions during the Cenozoic: consequences for the sedimentary record of saline lakes

Shoreline gypsiferous sediments of an inland lake in central Spain furnishes valuable insight into reconstructions of early sedimentary changes related to shore fly–microbial mat interactions in fossil gypsum precipitating saline lake systems. The association of adult and larval forms of Ephydra (Diptera) with microbial matgrounds overlying the lake margin results in the formation of gypsiferous meniscate back‐filled burrows that provide an analogue for recurring, extensively developed trace fossils that occur in Cenozoic, but not older, lacustrine gypsum rocks. In this setting, sediment burrowing by ephydridae hinders significant preservation of microbialites. The overwhelming rise of Diptera at the onset of the Cenozoic resulted in extensive feeding and dwelling activity and contributed to reshape the saline aquatic habitat where microbial mats thrived, thus leading to the formation of specific trace fossils that are illustrative of the existence of microbes in the paleoenvironment.     

Characterisation of streamflow regimes in central Spain, based on relevant hydrobiological parameters

The biotic composition, structure, and function of aquatic, wetland, and riparian ecosystem depend largely on the hydrological regime (Poff, N.L., Ward, J.V., 1990. Implications of streamflow variability and predictability for lotic community structure: a regional analysis of streamflow patterns. Can. J. Fisheries Aquat. Sci. 46, 1805–1818; Richter, B.D., Baumgartner, J.V., Wiginton, R., Braun, D.P., 1997 How much water does a river need? Freshwater Biol. 37, 231–249). Available flow data for many rivers in the world can be used to validate these ecological theories. There is a demand for studies that use hydrological indices to establish criteria, which serve to group together regime types at a local level. Once this has been done, these hydrologically similar groups can be used to identify communities of living organisms that are linked to specific aspects of the river's behaviour.

An approach to characterise flow regimes in the river network of the Tagus basin in Spain is presented. The river Tagus (río Tajo) is one of the seven major rivers of the Iberian peninsula. All hydrological data were acquired from the measurements made in the Tagus basin, at 25 gauging stations. Twelve variables were derived for each gauged site to describe variability and predictability of average streamflow conditions, and to describe the frequency, timing and intensity of high flow and low flow extremes.

A hierarchical clustering routine was used to identify similar groups of rivers as defined in terms of similar characteristics of their streamflow regime. The variables were also examined with simple correlations to determine if multicollinearity occurred, in order to reject redundant parameters or to identify similar behaviour trends between pairs of parameters. Some parameters have shown a tendency to increase or decrease along the east–west axis, suggesting that some of the studied characteristics may have a geographical cause.

Cluster analysis, with the values of the 12 parameters, reveals two main groups, each of which splits into two main subdivisions. One of these subgroups contains six rivers with similar characteristics, can be considered to be ‘classic regular rivers’, the stations in this first subgroup are mostly situated geographically close to each other. At the other end, we have found a subgroup, with a high variation of flows over the year and high flood flows; these rivers are highly irregular rivers with great changes. This regular–irregular gradient found between the groups is similar to that observed by others authors (Poff, N.L., Allan J.D., 1995. Functional organization of stream fish assemblages in relation to hydrological variability. Ecology 76, 606–627), and strong associations have been documented with compositions of populations and probably reflect differences in other similar important environmental factors.     

Operational earthquake loss forecasting: a retrospective analysis of some recent Italian seismic sequences

Operational earthquake forecasting (OEF) relies on real-time monitoring of seismic activity in an area of interest to provide constant (e.g., daily) updates of the expected number of events exceeding a certain magnitude threshold in a given time window (e.g., 1 week). It has been demonstrated that the rates from OEF can be used to estimate expected values of the seismic losses in the same time interval OEF refers to. This is a procedure recently defined as operational earthquake loss forecasting (OELF), which may be the basis for rational short-term seismic risk assessment and management. In Italy, an experimental OELF system, named MANTIS-K, is currently under testing. It is based on weekly rates of earthquakes exceeding magnitude (M) 4, which are updated once a day or right after the occurrence in the country of an M 3.5+ earthquake. It also relies on large-scale structural vulnerability and exposure data, which serve to the system to provide continuously the weekly expected number of: (1) collapsed buildings, (2) displaced residents, and (3) casualties. While the probabilistic basis of MANTIS-K was described in previous work, in this study OELF is critically discussed with respect to three recent Italian seismic sequences. The aim is threefold: (1) illustrating all the features of the OELF system in place; (2) providing insights to evaluate whether if it would have been a useful additional tool for short-term management; (3) recognizing common features, if any, among the losses computed for different sequences.     

Geometry of the neotectonic stress field in southern Italy: Geological and seismological evidence

The neotectonic regime in southern Italy has been evaluated by making a comparison between all the available structural and seismological data. The area investigated can be subdivided into four distinct zones which are characterized by different stress regimes. In the Southern Apennines the tensile axis of the stress field is oriented approximately NE-SW while the maximum principal stress (σ₁) is subvertical. In Northern Calabria, the tensile axis is ESE-WNW and the σ₁ axis is almost vertical. In the Catanzaro trough both the tensile axis and the σ₁ axis are subhorizontal and act E-W and N-S, respectively. Finally, the Strait of Messina zone is characterized by a tensile axis oriented E-W and by σ₁ being subvertical.     

Surface ozone measurements in the Venezuelan tropical savannah

A one-year set of surface ozone measurements in a four-station network located in the Venezuelan savannah is reported. The diurnal ozone variation is typical of continental stations with a maximum in the afternoon, when vertical turbulent mixing is strongest. The annual O₃ average concentration, based on the monthly averages of daily maxima, was 17±2 ppb, which is in good agreement with values reported for similar latitudes. The boundary-layer ozone levels did not fall below 8 ppb, in contrast with previous sporadic measurements made in tropical latitudes. No evidence was found that mesoscale O₃ downdrafts in the ITCZ in the South American continent are an important source of surface ozone. Finally, it is suggested that the relatively high ozone levels observed at the end of the dry season are probably of photochemical origin.     

Correlation of excursion sets for non-Gaussian cosmic microwave background temperature distributions

We present a method, based on the correlation function of excursion sets above a given threshold, to test the Gaussianity of the cosmic microwave background (CMB) temperature fluctuations in the sky. In particular, this method can be applied to discriminate between standard inflationary scenarios and those producing non-Gaussianity such as topological defects. We have obtained the normalized correlation of excursion sets, including different levels of noise, for two-point probability density functions constructed from the Gaussian, χ² _n and Laplace one-point probability density functions in two different ways. Considering subdegree angular scales, we find that this method can distinguish between different distributions even if the corresponding marginal probability density functions and/or the radiation power spectra are the same.