The biology and ecology of Valencia letourneuxi Sauvage 1880 (Valenciidae) - Prospects for conservation

Data are provided on the distribution, abundance, early development and biology of the endangered Greek endemic species Valencia letourneuxi Sauvage 1880, along with a record of its occurrence at new localities. V. letourneuxi is a small-bodied and short-lived insectivorous species, exhibiting cryptic colouration and sexual dimorphism. It matures in the first year of life, reproduces serially in late spring and summer, and deposits spherical eggs, around 2 mm, on aquatic plants. Most morphometric characters show size-specific trends, which complicate comparisons among populations or with other species. Of specific systematic importance is the relative position of the anal and dorsal fins, which remains almost unaltered throughout development, and allows safe distinction from A. fasciatus. The species was found mostly in deep areas with clean and slow running water, usually associated with freshwater springs. Rich submerged vegetation is the prominent ecological feature of all sites in which the species was found. Using as criteria of rarity the limited geographic distribution, the confinement of the species in few localities of each aquatic system and the low local densities, V. letourneuxi can be characterised as a "restricted and locally rare species". The restricted distribution, coupled with the narrow ecological requirements, makes the species vulnerable to extinction. Its disappearance from at least four aquatic systems and the serious population decline in a number of other systems seems to be connected with habitat loss or degradation caused by human activities. The prospects of conservation are discussed

Recent contributions to the distribution of the freshwater ichthyofauna in Greece

In this paper we supplement Greece’s recent annotated inventory of freshwater fishes per hydrographic basin with recent distributional data and taxa alteration information, based on field sampling and a literature review up to September 2011. We report on newly documented distributional records of 31 fish species plus one unidentified taxon, within 35 hydrographic river basin units in Greece. These new records include 14 native fish species, seven alien and 12 translocated. Translocated taxa are distinguished from aliens, in order to report species non-indigenous to a basin but native within the same ecoregion. Twelve hydrographic basin units are newly added to the roster of ichthyologically explored river basins following a previous basin-scale inventory method (the total is now 117). This review increases the number of Greece’s freshwater fish taxa to 167, since four new species are added to the list (Carassius langsdorfii, Neogobius fluviatilis, Telestes alfiensis, Millerigobius macrocephalus) and two are deleted (Salmo dentex, Barbus rebeli) due to taxonomic changes. Taxonomic changes will probably continue to alter the national list since phylogenetic research is ongoing on several taxa in many parts of the countr

The freshwater ichthyofauna of Greece - an update based on a hydrographic basin survey

Distribution records (historical, contemporary) for native and non-native freshwater fish species from 105 hydrographic basin areas were compiled and analysed in order to develop a nation-wide inventory (including transboundary river basins). Overall, 162 species, including diadromous and euryhaline, with documented occurrence records in freshwaters, and taxa of unclarified taxonomic status, are accommodated in the distributional compilation. An annotated checklist summarises the confirmed ichthyofauna of Greek freshwaters (161 species); a provisional supplementary list contains species recorded in brackish waters (55 species). In comparison to the last published (1991) checklist of freshwater fish of Greece, the present checklist shows an increase in species number of 53% (56 species). This increase has resulted mainly from taxonomic re-evaluations of existing taxa on the basis of new information and adoption of a new systematic concept. The current trend, as reflected in recent ichthyological publications, is towards abandonment of the biological species concept (BSC) and adoption of the phylogenetic species concept (PSC) for the delineation of species boundaries. The practical implications of the change in species concept on biodiversity conservation and watershed management are discussed. An overview of the composition and characteristics of the freshwater fish fauna of Greece is provided, especially with regard to the native and introduced status of species, and the spatial patterns of species richness and endemism. This systematic inventory may assist in efforts to develop nation-wide surface water bioassessment tools within the demands of the Water Framework Directive (WFD); it may further promote biodiversity conservation and biologically-orientated fishery management approaches

Quantum critical point in a periodic Anderson model

We investigate the symmetric Periodic Anderson Model (PAM) on a three-dimensional cubic lattice with nearest-neighbor hopping and hybridization matrix elements. Using Gutzwiller's variational method and the Hubbard-III approximation (which corresponds to the exact solution of an appropriate Falicov-Kimball model in infinite dimensions) we demonstrate the existence of a quantum critical point at zero temperature. Below a critical value $V_c$ of the hybridization (or above a critical interaction $U_c$) the system is an {\em insulator} in Gutzwiller's and a {\em semi-metal} in Hubbard's approach, whereas above $V_c$ (below $U_c$) it behaves like a metal in both approximations. These predictions are compared with the density of states of the $d$- and $f$-bands calculated from Quantum Monte Carlo and NRG calculations. Our conclusion is that the half-filled symmetric PAM contains a {\em metal-semimetal transition}, not a metal-insulator transition as has been suggested previously.Comment: ReVteX, 10 pages, 2 EPS figures. Minor corrections made in the text and in the figure captions from the first version. More references added. Accepted for publication in Physical Review

The ecology of the gadoid larvae in the northern North Sea

SIGLELD:D48083/83 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Magnetic phases of the Hubbard model

Employing the self consistent binary alloy approximation we obtain the ground state of the Hubbard model for various values of the electron concentration and the Coulomb repulsion U. © 1981

First finding of merenskyite (Pd,Pt)Te2 in porphyry Cu-Mo ores in Russia

Contents of Pt and Pd were determined in weakly mineralized rocks, ores, and flotation concentrates of the Aksug porphyry Cu-Mo deposit, northeastern Tuva. In all studied samples they are above the detection limits: Pt = 17-96 ppb and Pd = 9-924 ppb. These elements are unevenly distributed throughout the rocks and ores, with Pd/Pt varying from 0.5 to 37. Study of Pd-rich ores (up to 924 ppb, Pd/Pt = 37) on a JEOL JSM 5600 scanning electron microscope revealed finest (2-5 μm) merenskyite inclusions (25.20% Pd, 1.21% Pt, 72.31% Te) in chalcopyrite. The calculated crystallochemical formula of merenskyite from ores of the Aksug deposit is (Pd0.862Pt0.023Cu0.026Fe0.025)Te2.064. The merenskyite is associated with electrum (79.92% Au, 18.96% Ag), monazite, cobaltite, tennantite, and Sr-containing barite (4.6-18.0% Sr). Palladium mineralization occurs in massive chalcopyrite veinlets in zones of intensely propylitized rocks. The Devonian Aksug ore-bearing porphyry complex developed in the field of Early-Middle Cambrian intrusions of gabbro-diorite-plagiogranites associated with basalt-andesite effusions of island-arc complex. This might have led to high PGE contents in the Aksug rocks. The deposit formation proceeded with the participation of ore-bearing Cl-enriched fluids favoring the concentration and transport of PGE in porphyry copper systems. © 2007

Distribution of rhenium in molybdenite from porphyry Cu-Mo and Mo-Cu deposits of Russia (Siberia) and Mongolia

Rhenium was determined in representative molybdenite samples (concentrates) from the Aksug, Erdenetuin-Obo, Zhireken, Shakhtama and Sora porphyry Cu-Mo and Mo-Cu deposits of Russia (Siberia) and Mongolia. The Re contents in the majority of the concentrates are low, ranging from 6 to 460 ppm. The maximum Re contents were determined in molybdenite concentrates from the Aksug (460 ppm Re) and Erdenetuin-Obo (199 ppm Re) Co-Mo porphyry deposits and are significantly higher than those from the Zhireken, Shakhtama and Sora Mo-Cu porphyry deposits. The Re content of molybdenite concentrates from the studied Mo-Cu porphyry deposits (6 to 57 ppm) are, however, comparable to those from comparable deposits worldwide. The Aksug and Erdenetuin-Obo deposits, with relatively elevated Re content, differ from the Zhireken, Shakhtama and Sora deposits with lower Re contents in terms of (1) higher Cu/Mo ratio; (2) lower δ34S and 87Sr/86Sr values; (3) silica and alkali contents of the host rocks; (4) the alteration type of the associated rocks; (5) the elevated Cl activity in the fluid; (6) the lower temperature of the molybdenite formation; and (7) the higher oxidized conditions. The Re contents of molybdenite from porphyry Cu-Mo deposits may therefore be related to the composition of parent magmas themselves and/or fractionation, sources of the material, and variations of physical and chemical conditions of crystallization (fO2, Cl activity, P, T). © 2005 Elsevier B.V. All rights reserved

Cross-cultural adaptation and validation of the Greek version of the Family Questionnaire for assessing expressed emotion

Expressed emotion (EE) has proved to be an established factor in short-term relapse in schizophrenia the aim of the present study was to examine the psychometric properties of the Greek version of the Family Questionnaire (FQ), a brief self-report questionnaire measuring the EE status of relatives of patients with schizophrenia in terms of criticism (CC) and emotional overinvolvement (EOI) the translated and adapted 20-item FQ was administered to 176 family caregivers of patients with schizophrenia and bipolar disorder. Caregivers' burden (Family Burden Scale) and psychological distress (General Health Questionnaire-28) were also evaluated the findings indicated that the Greek version displays a two-factor structure with two subscales of EE - CC and EOI - with 10 items each, similarly to the original version the convergent validity of the subscales was highly supported by correlations with caregivers' burden and psychological distress the Cronbach's α coefficient measuring internal consistency for the two scales were 0.90 for CC and 0.82 for EOI the test-retest correlation coefficients measuring reproducibility were 0.99 and 0.98 for CC and EOI, respectively the Greek version of the FQ appears to be a valid and reliable instrument to be used in both research and clinical assessment of family EE. © 2014 Elsevier Inc

Phylogenetics and biogeography of the Balkan ‘sand gobies’ (Teleostei: Gobiidae): vulnerable species in need of taxonomic revision

Within the Atlantic–Mediterranean region, the ‘sand gobies’ are abundant and widespread, and play an important role in marine, brackish, and freshwater ecosystems. They include the smallest European freshwater fish, Economidichthys trichonis, which is threatened by habitat loss and pollution, as are several other sand gobies. Key to good conservation management is an accurate account of the number of evolutionary significant units. Nevertheless, many taxonomic and evolutionary questions remain unresolved within the clade, and molecular studies are lacking, especially in the Balkans. Using partial 12S and 16S mitochondrial ribosomal DNA sequences of 96 specimens of at least eight nominal species (both freshwater and marine populations), we assess species relationships and compare molecular and morphological data. The results obtained do not support the monophyly of Economidichthys, suggesting the perianal organ to be a shared adaptation to hole-brooding rather than a synapomorphy, and urge for a taxonomic revision of Knipowitschia. The recently described Knipowitschia montenegrina seems to belong to a separate South-East Adriatic lineage. Knipowitschia milleri, an alleged endemic of the Acheron River, and Knipowitschia cf. panizzae, are shown to be very closely related to other western Greek Knipowitschia populations, and appear conspecific. A distinct Macedonian–Thessalian lineage is formed by Knipowitschia thessala, whereas Knipowitschia caucasica appears as an eastern lineage, with populations in Thrace and the Aegean. The present study combines the phylogeny of a goby radiation with insights on the historical biogeography of the eastern Mediterranean, and identifies evolutionary units meriting conservation attention