New records of cold‐water coral sites and fish fauna characterization of a potential network existing in the Mediterranean Sea

New cold‐water coral (CWC) sites were recorded along the Apulian margin (Central Mediterranean). The species composition and depth distribution of CWCs were updated. A distribution of the CWC sites coincident with the course of the dense‐water masses that flow between the Southern Adriatic and Northern Ionian was confirmed. The faunal assemblages of five of these CWC sites were investigated and compared using experimental longlines during the spring–summer and autumn–winter seasons, between 2010 and 2014. Differences in ecological variables amongst the sites in each season were evaluated by means of a set of univariate and multivariate methods (analysis of variance, permutational multivariate analysis of variance, non‐metric multidimensional scaling). Although some differences were detected in relation to the different depths examined during spring–summer, the CWC sites showed similar features in terms of species richness and diversity as well as in the abundance of the same fish species (Galeus melastomus, Conger conger, Helicolenus dactylopterus, Merluccius merluccius, Phycis blennoides and Pagellus bogaraveo) most probably because of the distribution of adult specimens in structurally complex and heterogeneous habitats, which act as a potential ‘refuge network’ with respect to commercial fishing. The presence of maturing and mature individuals as well as post‐reproductive females indicates that these CWC sites also act as spawning areas, representing a potential ‘renewal network’ for the fish populations. The term ‘network’ used here refers to several similar subsystems (CWC sites) that play the same ecological role in a wider system (Apulian margin). These CWC communities need coherent conservation measures and management strategies according to the Ecosystem Approach to Fisheries.     

The gamma ray background from large scale structure formation

Hierarchical clustering of dark matter halos is thought to describe well the large scale structure of the universe. The baryonic component of the halos is shock heated to the virial temperature while a small fraction of the energy flux through the shocks may be energized through the first order Fermi process to relativistic energy per particle. It has been proposed that the electrons accelerated in this way may upscatter the photons of the universal microwave background to gamma ray energies and indeed generate a diffuse background of gamma rays that compares well to the observations. In this paper, we calculate the spectra of the particles accelerated at the merger shocks and re-evaluate the contribution of structure formation to the extragalactic diffuse gamma ray background (EDGRB), concluding that this contribution adds up to at most 10% of the observed EDGRB.     

A new general frequency-magnitude relationship

A new frequency-magnitude relationship which takes into account the existence of an upper limit for the magnitude, and generalizes the previous ones, is proposed. The formula obtained has been applied to the Western Alps area activity during the period 1950–75, and in addition to the limiting magnitude value, some useful results for the calculation of the seismic risk have been deduced using Gumbel's theory. The use of the present relationship appears to be necessary when long periods of time are considered, while for the study of the annual probabilities the Gutenberg and Richter formula is shown to be sufficiently accurate.     

The Bushveld granites around Rooiberg,Transvaal, South Africa

The detailed investigation of the Bushveld granites, around the Rooiberg area, has revealed the existence, in the field, of at least three main types:

1. Granophyric rocks, which form a belt (transition-zone) between the country rocks (sediments and felsite) and the Main granite.
2. Main granite, which is the most common type of granite.
3. Younger granites, which are responsible for the tin mineralization.

All evidence points to a metasomatic origin for the granophyric rocks. For the Main granite, a probable anatectic origin is proposed, which is borne out by the presence of ghost-stratigraphy patterns, detected by trend surface analysis. The younger granites are undoubtely magmatic. On account of parallelism between the structural lines of the granitic rocks and the country rocks, an hypothesis based on deformation contemporaneous with the emplacement of the granites is advanced to explain the structure of the Rooiberg Area. In view of this hypothesis, the “Rooiberg roof-pendant” is considered to be probably a portion of the roof in its normale position.     

A possible mechanism for the thermal asymmetry of the Ligurian basin

ABSTRACT We propose a thermo-mechanical model and a new interpretation of heat flux data for the Ligurian basin that may be a key to understanding the evolution of the NW Mediterranean. The model incorporates the removal of a portion of mantle lithosphere to explain the heat-flux and subsidence anomaly of the eastern (Corsican) margin of the basin. This process is envisaged as a result of eastward asthenosphere flow induced by the Apennines subduction system. After a heating phase, time-dependent conductive cooling and re-thickening of the lithosphere result in re-equilibrium of the thermal gradient to its initial value. Such a rifting mode can account for the asymmetric heat-flux and subsidence pattern observed across the basin and the present-day lithospheric thickness.     

Contribution to the solution of the three-body problem in power series form

After reviewing the existing procedures for solving the three-body problem by convergent power series, the author develops two algebraic methods in terms of the independent variable which is either the time t or Levi-Civita's regularizing variable u. These power series solve in Weierstrass' and Painlevé's sense the problem formulated in its greatest generality, since no restrictions at all are made on the order of magnitude of masses and none of the three bodies is restricted to moving along a prescribed conic section. Besides, the reference system used is a tridimensional Cartesian one. In the t-domain, the expressions for the high-order derivatives of the coordinates are computed using repeatedly Leibnitz's rule for derivatives of products of functions. In the u-domain, an extremely simple successive approximation procedure is established by means of a single recursion formula which requires elementary operations to be performed on polynomials of increasing degrees.     

Caisson breakwaters embodying an OWC with a small opening—Part II: A small-scale field experiment

A common and intuitive idea is that, before an absorbing breakwater, waves are smaller than before a conventional reflecting breakwater. The theory of Part I has shown that, on the contrary, before a breakwater converter, in some cases, the wave height may be greater than before a conventional reflecting breakwater. Now, an experiment off the eastern coast of the Straits of Messina provides a confirmation of the theory: some huge amplifications of swells are common at a breakwater converter, and as a consequence the energy absorption gets very large. Here, we show the results of the experiment, and, basing ourselves on these results and on the theory of Part I, we suggest some practical way of calculation.     

Vertical dynamics of disc galaxies in modified Newtonian dynamics

We investigate the possibility of discriminating between modified Newtonian dynamics (MOND) and Newtonian gravity with dark matter, by studying the vertical dynamics of disc galaxies. We consider models with the same circular velocity in the equatorial plane (purely baryonic discs in MOND and the same discs in Newtonian gravity embedded in spherical dark matter haloes), and we construct their intrinsic and projected kinematical fields by solving the Jeans equations under the assumption of a two-integral distribution function. We find that the vertical velocity dispersion of deep MOND discs can be much larger than in the equivalent spherical Newtonian models. However, in the more realistic case of high surface density discs, this effect is significantly reduced, casting doubt on the possibility of discriminating between MOND and Newtonian gravity with dark matter by using current observations.