1,721,084 research outputs found
First record of Pachygrapsus transversus (Gibbes, 1850) (Brachyura, Grapsidae) in Italian waters.
No full textPachygrapsus transversus (Gibbes, 1850) is reported for the first time from Italian waters. This crab was collected at Ustica Island and at several other localities on NWSicily (southern Tyrrhenian Sea) on vermetid reefs, an intertidal habitat frequent in the sampling area. P. transversus, whose distributional range covers the warm and warm-temperate areas of the eastern and western Atlantic and the eastern Pacific, was already known from the eastern Mediterranean since the 1920s; prior to this paper it was recorded in the western Mediterranean only in 1980 and 1994 with very few specimens.
There are no data to ascertain the origin of the Sicilian population, i.e., natural or ship-mediated diffusion; either is considered possible in theory. Yet, the presence of young specimens (around 5 mmcarapace length) and ovigerous females, as well as the numerical abundance at one of the Sicilian sites, suggest that the NW Sicily population is stable and well acclimatized
The marine crustacea decapoda of Sicily: a cecklist with remarks on their distribution.
No full textA checklist of the Crustacea Decapocla of Sicily, based on previously published records and on original data, is presented. The Sicilian waters were divided into three sectors to account for the different habitats present along the northern and western (sector A), eastern (B) and southern (C) coasts, for the sake of a better interpretation of the species distribution. A total of 186 species, vas recorded between 0 and 800 in depth, 31 of which are reported here for the first time. Sector A hosted 153 species, B 105 species. and C 117 species. The dissimilarities among the habitats present in the shallow waters of the three sectors accounted for the low co-occurrence of species: 30 species were common to A and C. 13 to A and B. and 2 to B and C. Seventy-two species co-occurred in the three sectors, recorded mainly in offshore soft bottoms investigated by trawl surveys. The importance of the aid given by such surveys, as well as by stomach contents analysis, in support of faunistic studies is highlighted. Lastly the affinity of the Mediterranean decapod fauna with that of the northeastern Atlantic is briefly discussed
The effects of cors network geometry and differential nrtk corrections on gnss solutions
Full text linkThe widespread availability of Continuosly Operating Reference Station (CORS) all over the world, allows to improve more scientific and technical studies on the use of satellite positioning techniques. The aim of this paper is to understand the effects of a GNSS CORS network geometry and differential corrections on the solutions. The analysis is carried out using ten different network configurations, with different inter-distances between the stations within GNSMART Geo++ software. The coordinates of one control point placed on the top of the Department of Engineering (University of Palermo, Italy) have been used to perform several static positioning mode test within fourthy hours. Different surveys have been performed, including four separate session tests, with acquisitions of one hour each. The analysis has been carried out using the traditional network solutions, such as the Virtual Reference Station (VRS), the Flächen Korrektur Parameter (FKP) and other two more recent techniques, which use the satellite corrections from the nearest (Near) and the farest (Far) stations. Results confirmed the great reliability of the GNSS network, with centimetre precision in terms of coordinates (North, East and Ellipsoidal Height), whether changing the geometric configuration of the network or the corrections
Crustacea Decapoda from Ustica (Southern Tyrrhenian Sea): species distribution and sampling approach.
No full textThe decapod crustacean fauna of Ustica Island (Sicily, southern Tyrrhenian Sea) has been investigated in summer 2002 with the aid of many different sampling methods: suction device, pushnet, skid trawl, trammel net, traps, underwater observation, interviews. All the substrata
occurring around the island from 0 to about -30 m were surveyed: midlittoral rock, infralittoral
rock, pebbles, seagrass (Posidonia oceanica) bed, sand, detritic bottom, submerged cave. Fiftyseven
species were collected in the investigated localities. Abundance and frequency of all
species in the samples and in each surveyed biotope are given. The performance of each sampling
method has been evaluated, in terms of number of species and individuals, and of species
unique to each method.Methods based on direct underwater observation (i.e., visual census) and
hand collection provided the largest number of species. Accounts on three remarkable species
are given: Calappa tuerkayana, Pachygrapsus transverses, and Percnon gibbesi. This study increases the decapod knowledge of the southern Tyrrhenian sea
GNSS CORS NETWORK OF THE UNIVERSITY OF PALERMO: DESIGN AND FIRST ANALYSIS OF DATA
Full text linkNowadays, technical and scientific researches are focused on the use of Global Navigation
Satellite System (GNSS) Continuously Operating Reference Stations (CORS) networks due
to their global impact on the satellite positioning. This study aims to describe the main steps
developed by the University of Palermo for the realization of the GNSS CORS network
distributed in the western part of Sicily (Italy). Specifically, it focuses on data availability,
preliminary studies and analyses involving the GNSS CORS network, the geodetic
framework used, the coordinates and displacements time series retrieved over time and the
statistical analysis with the Cumulative Distribution Function (CDF). The analyses allowed
to verify the network operating service and the quality of the recorded data during the first
period of testing procedure (2008 – 2012
Maja goltziana d'Oliveira, 1888 (Decapoda, Brachyura, Majidae) in the southern Tyrrhenian Sea.
No full textMaja goltziana d’Oliveira, 1888 is an oxyrhynch crab occurring in the eastern Atlantic Ocean from Portugal to Congo and the Canary Islands, and in the Mediterranean Sea (d’Udekem d’Acoz, 1999). It is apparently uncommon all across its distributional range, although González Pérez (1995) describes it as a frequent species on the Canary Islands. In the Mediterranean, it is by far the least common of the Maja species, among which it can easily be distinguished by the morphological characteristics of the dorsal part of the carapace and of the walking legs.
The present paper reports about two findings of M. goltziana in the southern Tyrrhenian, and confirms its established presence in the western Mediterranean Sea
The structural versatility of proton sponge bismuth halides
Full text linkHybrid halometalates containing lead, tin, bismuth and antimony and organic cations have recently shown a bevy of interesting photophysical properties. Aiming at finding chemically stable and thermally inert species, three halobismutate species of this class, crystallized with proton sponge-derived cations (PRSH), have been isolated as microcrystalline powders by mixing 1,8-bis(dimethylamino)-naphthalene (proton sponge, or PRS) and bismuth oxide in concentrated HX acids (X = Cl, Br and I). The two isomorphous (PRSH)3Bi2X9 (X = Br, I) species, containing isolated [Bi2X9]3- anions, are triclinic at room temperature and convert upon heating into a monoclinic structure through a displacive phase transformation, fully reversible for X = I and only partially for X = Br. At variance, (PRSH)BiCl4 is polymeric, and contains extended zigzagging 1D chains formed by edge-sharing BiCl6 octahedra. These species were extensively studied by synchrotron and laboratory X-ray powder diffraction measurements, which enabled to detect the evolution toward the two high-temperature β-phases (X = Br, I), to derive the structure of five different (significantly complex) species and to assess the thermal strain tensors in the different regimes. Additional thermal, spectroscopic and computational analyses completed the characterization of these materials
First estimates of density and distribution of the alien crab Percnon gibbesi (Decapoda, Percnidae) in the “Capo Gallo-Isola delle Femmine” MPA
No full text- …
