270 research outputs found
Aggregate ranking of the world's leading universities
The paper presents a methodology for calculating the aggregate global university ranking (Aggregated Global University Ranking, or AGUR), which consists of an automated presentation of the comparable lists of names for different universities from particular global university rankings and a simple procedure of aggregating particular global university rankingsyesBelgorod State Universit
First assessment of biomass and abundance of cephalopods Rossia palpebrosa and Gonatus fabricii in the Barents Sea
Copyright © Marine Biological Association of the United Kingdom 2016Studies on the quantitative distribution of cephalopods in the Arctic are limited, and almost completely absent for the Barents Sea. It is known that the most abundant cephalopods in the Arctic are Rossia palpebrosa and Gonatus fabricii. Their biomass and abundance have been assessed for the first time in the Barents Sea and adjacent waters. The maximum biomass of R. palpebrosa in the Barents Sea was 6.216–6.454 thousand tonnes with an abundance of 521.5 million specimens. Increased densities of biomass were annually registered in the north-eastern parts of the Barents Sea. The maximum biomass of G. fabricii in the Barents Sea was 24.797 thousand tonnes with an abundance of 1.705 billion specimens. The areas with increased density of biomass (higher than 100 kg km−2) and abundance (more than 10,000 specimens km−2) were concentrated in deep-water troughs in the marginal parts of the Barents Sea and in adjacent deep-water areas. The biomass and abundance of R. palpebrosa and G. fabricii in the Barents Sea were much lower than those of major taxa of invertebrates and fish and than those of cephalopods in other parts of the World Ocean. It has been suggested that the importance of cephalopods in the Arctic ecosystems, at least in terms of quantitative distribution, could be somewhat lower than in the Antarctic or the tropics. Despite the impact of ongoing warming of the Arctic on the distribution of cephalopods being described repeatedly already, no impact of the current year's climate on the studied species was found. The only exception was the abundance of R. palpebrosa, which correlated with the current year's climate conditions
Finding of the lesser flying squid (Todaropsis eblanae, oegopsida, ommastrephidae) from the Barents Sea
A specimen of the squid Todaropsis eblanae (Ball 1841) was caught in the Barents Sea by a pelagic trawl for the first time (71°13'N-36°38'E, 0-60-m trawling horizon, at a depth of 225 m). The maturing squid male caught had 29 spermatophores in spermatophoric sac, dorsal mande of 92 mm long, and body weight of 67.3 g. Obviously, this specimen has come here from the North Sea along the eastern branch of the Norwegian current and southern branch of the Nordcap current
Changes in distribution and range structure of Arctic cephalopods due to climatic changes of the last decades
The warming of Arctic waters over the last decades has been confirmed by the results of numerous studies. New data on distribution of cephalopods in the Arctic were obtained from the research cruises of PINRO (Russia) and IMR (Norway) during 2006-2011. Teuthowenia megalops and Todaropsis eblanae were found in the Arctic for the first time, at distances of more than 1000 km and 2500 km outside of their ranges, respectively. The demersal species T. eblanae inhabiting the lower shelf and upper continental slope has presumably spread into the Barents Sea by the eastern branch of the Norwegian Current, and further by the southern branch of the North Cape coastal current, as far as the Murman shelf. The bathypelagic species T. megalops is carried to the Arctic evidently by the deep-water warm Atlantic Currents. The new spreading areas of both species are obviously the non-reproductive zones of their ranges. Foraging shoals of Todarodes sagitatus were recorded in the Arctic in 2010 for the first time in the last 25 years, which can be related to not only the warming of Arctic waters, but also the fluctuation of Todarodes levels in the main part of the range in the Northern Atlantic. The native Arctic species Gonatus fabricii has expanded its range to the eastern part of the Barents Sea and to the adjacent part of the Kara Sea. In these areas of Arctic waters, warming is particularly noticeable and the ongoing climatic changes are leading to boreal cephalopods spreading into the Polar Basin. This may impact species relations in vulnerable Arctic ecosystems. © 2013 Copyright Taylor and Francis Group, LLC
Structure of the reproductive system and hectocotylus in males of lesser flying squid Todaropsis eblanae (Cephalopoda: Ommastrephidae)
This paper introduces new data on Todaropsis eblanae morphology, morphometry and functional aspects of the male reproductive system and hectocotylus. Spermatophores differ in specimens from the Atlantic Ocean (average length, 18.28 ± 1.45 mm, 15.63 ± 0.8% of mantle length; weight, 2.0-12.0 mg) and the Indian Ocean (average length, 24.8 ± 2.85 mm, 16.9 ± 2.1% of mantle length; weight, 35.0-39.6 mg) (t = 3.14; p 001 for relative sizes). An additional important distinctive trait is the form of connection of the cement body with the ejaculatory tube. In recent years, T. eblanae has been regularly caught in the Barents Sea, meaning its range has extended to subarctic waters. The morphology and morphometry of the spermatophoric complex of organs did not vary in investigated parts of its range. Hectocotylus patterns and some important spermatophore traits distinguish Todaropsis from other Ommastrephidae. © 2012 Copyright Taylor and Francis Group, LLC
On the superfluidity of classical liquid in nanotubes
In 2001, the author proposed the ultra second quantization method. The ultra
second quantization of the Schr\"odinger equation, as well as its ordinary
second quantization, is a representation of the N-particle Schr\"odinger
equation, and this means that basically the ultra second quantization of the
equation is the same as the original N-particle equation: they coincide in
3N-dimensional space.
We consider a short action pairwise potential V(x_i -x_j). This means that as
the number of particles tends to infinity, , interaction is
possible for only a finite number of particles. Therefore, the potential
depends on N in the following way: . If V(y) is finite
with support , then as the support engulfs a finite
number of particles, and this number does not depend on N.
As a result, it turns out that the superfluidity occurs for velocities less
than , where
is the critical Landau velocity and R is the radius of
the nanotube.Comment: Latex, 20p. The text is presented for the International Workshop
"Idempotent and tropical mathematics and problems of mathematical physics",
Independent University of Moscow, Moscow, August 25--30, 2007 and to be
published in the Russian Journal of Mathematical Physics, 2007, vol. 15, #
The northernmost record of Sepietta oweniana (Cephalopoda: Sepiolidae) and omments on boreo-subtropical cephalopod species occurrence in the arctic
© Marine Biological Association of the United Kingdom, 2014. The first observation of the common bobtail squid Sepietta oweniana has been made in the Barents Sea (Tromsø Bank; 70°54′ N 19°46.8′E). It is the northernmost area of this species distribution. No changes were found in the reproductive system structure. But the food spectrum was changed, particularly, juvenile fish of the Lotidae family was found. The bobtail squid of the Sepiolinae subfamily have never been recorded as fish eaters previously. The expansion of boreosubtropical species of cephalopods into the Arctic during the last decade can be divided into two groups: (1) a foraging migration happening relatively regularly; and (2) a range expansion due to the ongoing Arctic warming. The case of S. oweniana obviously belongs to the second group
Sn delta-doping in GaAs
We have prepared a number of GaAs structures delta-doped by Sn using the
well-known molecular beam epitaxy growth technique. The samples obtained for a
wide range of Sn doping densities were characterised by magnetotransport
experiments at low temperatures and in high magnetic fields up to 38 T.
Hall-effect and Shubnikov-de Haas measurements show that the electron densities
reached are higher than for other delta-dopants, like Si and Be. The maximum
carrier density determined by the Hall effect equals 8.4x10^13 cm^-2. For all
samples several Shubnikov-de Haas frequencies were observed, indicating the
population of multiple subbands. The depopulation fields of the subbands were
determined by measuring the magnetoresistance with the magnetic field in the
plane of the delta-layer. The experimental results are in good agreement with
selfconsistent bandstructure calculations. These calculation shows that in the
sample with the highest electron density also the conduction band at the L
point is populated.Comment: 11 pages text (ps), 9 figures (ps), submitted to Semicon. Science
Tech
Large-scale Samples Irradiation Facility at the IBR-2 Reactor in Dubna
The irradiation facility at the beam line no.3 of the IBR-2 reactor of the Frank Laboratory for Neutron Physics is described. The facility is aimed at irradiation studies of various objects with area up to 800 cm both at cryogenic and ambient temperatures. The energy spectra of neutrons are reconstructed by the method of threshold detector activation. The neutron fluence and dose rates are measured by means of alanine and thermoluminescent dosimeters. The boron carbide and lead filters or converter provide beams of different ratio of doses induced by neutrons and photons. For the lead filter, the flux of fast neutrons with energy more than 0.1 MeV is \fln and the neutron dose is about 96\% of the total radiation dose. For the converter, the dose rate is 500 Gy h which is about 85\% of the total dose. The radiation hardness tests of GaAs electronics and materials for the ATLAS detector to be put into operation at the Large Hadron Collider (LHC) have been performed successfully at this facility
Diversity of hard-bottom fauna relative to environmental gradients in Kongsfjorden, Svalbard
A baseline study of hard-bottom zoobenthos in relation to environmental gradients in Kongsfjorden, a glacial fjord in Svalbard, is presented, based on collections from 1996 to 1998. The total species richness in 62 samples from 0 to 30 m depth along five transects was 403 species. Because 32 taxa could not be identified to species level and because 11 species are probably new to science, the total number of identified species was 360. Of these, 47 species are new for Svalbard waters. Bryozoa was the most diverse group. Biogeographic composition revealed features of both Arctic and sub-Arctic properties of the fauna. Species richness, frequency of species occurrence, mean abundance and biomass generally decreased towards the tidal glaciers in inner Kongsfjorden. Among eight environmental factors, depth was most important for explaining variance in the composition of the zoobenthos. The diversity was consistently low at shallow depths, whereas the non-linear patterns of species composition of deeper samples indicated a transitional zone between surface and deeper water masses at 15–20 m depth. Groups of “colonial” and “non-colonial” species differed in diversity, biogeographic composition and distribution by location and depth as well as in relation to other environmental factors. “Non-colonial” species made a greater contribution than “colonial” species to total species richness, total occurrence and biomass in samples, and were more influenced by the depth gradient. Biogeographic composition was sensitive to variation of zoobenthic characteristics over the studied depth range. A list of recorded species and a description of sampling sites are presented
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