110 research outputs found
Enhancement of the critical temperature in iron-pnictide superconductors by finite size effects
Recent experiments have shown that, in agreement with previous theoretical
predictions, superconductivity in metallic nanostructures can be enhanced with
respect to the bulk limit. Motivated by these results we study finite size
effects (FSE) in an iron-pnictide superconductor. For realistic values of the
bulk critical temperature Tc ~ 20-50K, we find that, in the nanoscale region L
~ 10 nm, Tc(L) has a complicated oscillating pattern as a function of the
system size L. A substantial enhancement of Tc with respect to the bulk limit
is observed for different boundary conditions, geometries and two microscopic
models of superconductivity. Thermal fluctuations, which break long range
order, are still small in this region. Finally we show that the differential
conductance, an experimental observable, is also very sensitive to FSE.Comment: 4 pages, 3 figure
Evaluation of left renal vein and inferior vena cava variations through routine abdominal multi-slice computed tomography
Background: The aim of this study was to evaluate the frequency of left renal vein (LRV) and inferior vena cava (IVC) variations and the effect of gender on this frequency, as well as the presence of associated abdominal pathologies.Materials and methods: Multi-slice computed tomography (MSCT) images from 746 patients were evaluated retrospectively.Results: Left renal vein variations were identified in 9.8% of cases, while retroaortic LRV (RLRV) and circumaortic LRV (CLRV) were found in 7.4% and 2.4% of cases, respectively. No significant correlation was found between gender and LRV variations (p = 0.797). Of the cases with LRV and IVC variations, 73% had abdominal pathologies, the most common of which were nephrolithiasis, which appeared in 18 (32%) cases, and renal cysts, which appeared in 14 (25.4%) cases.Conclusions: MSCT is a rapid and reliable method of identifying LRV and IVC variations and associated abdominal pathologies
Shell Structure and Strengthening of Superconducting Pair Correlation in Nanoclusters
The existence of shell structure and the accompanying high degeneracy of
electronic levels leads to the possibility of strong superconducting pairing in
metallic nanoclusters with N~100-1000 delocalized electrons. The most favorable
cases correspond to (a) "magic" clusters with strongly degenerate highest
occupied and lowest unoccupied shells and a relatively small energy spacing
between them as well as to (b) clusters with slightly incomplete shells and
small Jahn-Teller splitting. It is shown that realistic sets of parameters lead
to very high values of Tc as well as to a strong alteration of the energy
spectrum. The impact of fluctuations is analyzed. Spectroscopic experiments
aimed at detecting the presence of pair correlations are proposed. The pairing
should also manifest itself via odd-even effects in cluster spectra, similar to
the case of nuclei
New Mediterranean Biodiversity Records (April, 2014)
According to reports, the following 16 species have extended their distribution to other Mediterranean areas or have made a new appearance in other regions. The first category includes the following organisms: The rare and common Indo-Pacific seaweed Codium arabicum (Lebanese coasts), the acari Thalassarachna affinis (Marmara Sea), and the non-indigenous nudibranch Flabellina rubrolineata, which has also been found in many other areas of the Aegean Sea. In addition, the rare sea slug Thecacera pennigera (Piccolo of Taranto), the fangtooth moray Enchelycore anatina (National Marine Park of Zakynthos, Ionian Sea), the carangid Seriola fasciata (Gulf of Antalya), Lagocephalus sceleratus (SE. Ionian Sea), the reticulated leatherjacket Stephanolepis diaspros (Slovenia, N. Adriatic Sea), the marbled stingray, Dasyatis marmorata (NE Levantine), the starry smooth-hound Mustelus asterias (Iskenderun Bay, NE Mediterranean), the cephalopod Ommastrephes bartramii (Ionian Sea) have also been reported. The Atlantic crab Dyspanopeus sayi has expanded to many Italian areas and the blue crab Callinectes sapidus to a lake in N. Greece and in the S. Adriatic Sea. Finally, Farfantepenaeus aztecus has been found in the Ionian Sea, thus showing its wide expansion in the Mediterranean. The larval stages of Faccionella oxyrhyncha have been found, after many years, in the Aegean Sea and the first report of an existence on intersexual acari Litarachna duboscqi in Split(Adriatic Sea) was reported
New mediterranean biodiversity records (November, 2016)
This Collective Article presents information on 26 taxa belonging to 8 Phyla and extending from the western Mediterranean to the Levantine Sea. The new records were found in 9 countries as follows: Spain: first record for the Mediterranean of the crab Cancer bellianus; Algeria: further records of the alien fish Lagocephalus sceleratus in western Algerian waters; Italy: first report on the presence and establishment of the ctenophore Mnemiopsis leidyi in Lessina and Varano Lagoons (W. Adriatic) and of Penaeus aztecus in Corigliano Gulf (Italian Ionian). Moreover, the extension of the distribution range of the polychaete Branchiomma bairdi to W. Sicily as well as that of the crab Ocypode cursor and the bryozoan Catenicella paradoxa to E. Sicily are cited. Slovenia: the record of the rare saccoglossan gastropod Placida cremoniana from Piran (Gulf of Trieste) is the first for the Adriatic; Greece: the native sea slug Eubranchus farrani is the first from the Eastern Mediterranean; many sightings of the bamboo corals Isididae distributed along all the E. Ionian Sea and the establishment of P. aztecus in all Greek waters are also reported for first time; the westernmost extension of the alien urchin Diadema setosum in Cretan waters is cited and new sightings of the alien species Goniobranchus annulatus and Pterois miles are presented. Turkey: the alien fish Champsodon capensis is reported for first time from the Aegean Sea and the native acari Agauopsis microrhyncha from the Levantine Sea; a new observation of the alien crab Atergatis roseus in Güllük Bay-Aegean is also mentioned; Cyprus: first records of the alien urchin D. setosum and Lobotes surinamensis in Cypriot waters; Lebanon: several sightings of Monachus monachus from Lebanese waters indicate a potential better status for the species in the area; Egypt: first records of the alien crab Dorippe quadridens and the alien gastropods Nerita sanguinolenta and Conomurex persicus from the Mediterranean Egyptian waters; extension of the distribution range of Diodora funiculata and Diodora rueppellii and a second record of the alien Fulvia fragilis in the same area
Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine
[This corrects the article DOI: 10.1186/s13054-016-1208-6.]
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