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Number of results: 81
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Abstract

One of the most significant global climatic events in the Cenozoic was the transition from greenhouse to icehouse conditions in Antarctica. Tectonic evolution of the region and gradual cooling at the end of Eocene led to the first appearance of ice sheets at the Eocene/Oligocene boundary (ca. 34 Ma). Here we report geological record of mountain glaciers that preceded major ice sheet formation in Antarctica. A terrestrial, valley-type tillite up to 65 metres thick was revealed between two basaltic lava sequences in the Eocene– Oligocene Point Thomas Formation at Hervé Cove – Breccia Crag in Admiralty Bay, King George Island, South Shetland Islands. K-Ar dating of the lavas suggests the age of the glaciation at 45–41 Ma (Middle Eocene). It is the oldest Cenozoic record of alpine glaciers in West Antarctica, providing insight into the onset of glaciation of the Antarctic Peninsula and South Shetland Islands.
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Abstract

Ostracods from Admiralty Bay on King George Island (South Shetland Islands) represent 29 podocopid species, belonging to 19 genera, one cladocopid and six myodocopid species. They were recovered from Recent marine and/or glacio-marine sediment samples from water depths of up to 520 m. These ostracods constitute a variable assemblage, which is overall typical for the Antarctic environment. Shallow-water assemblages tend to be more variable in terms of frequencies and species richness than deep-water assemblages. The later are low in numbers and remain relatively high diversities. Overall, no linear relation between ostracod assemblage-composition and environmental features analyzed was recognized.
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Abstract

The two bathydraconid species, Gymnodraco acuticeps and Cygnodraco mawsoni, caught in the Ross Sea (Antarctic summer 2002) were examined for internal parasites. All specimens (four G. acuticeps and one C. mawsoni) were infected. G. acuticeps harboured larval Cestoda (bilocular tetraphyllidean cercoids, diphyllobothriid plerocercoids) and Nematoda (Contracaecum spp.), acanthocephalan cystacanths and adult helminths (three species of Digenea and one species of Nematoda). Two specimens of C. mawsoni (including data from one additional specimen examined earlier) were infected by larval Cestoda (bilocular cercoid) and Nematoda (Contracaecum spp.) and adult helminths (three species of Digenea and one species of Nematoda). The present data are compared and discussed with the relevant literature data.
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Abstract

This is a second paper dealing with juvenile and little known Mesozoic gastropods from Siberia and the Timan region. This part contains description of gastropods belonging to Neogastropoda and Heterobranchia. Described are 16 species, five of them are new. They are: Sulcoactaeon uralicus, S. timanicus, S. bojarkensis (Bullinidae), Vasjugania vasjuganensis (Acteonidae), and Biplica siberica (Ringiculidae). The new genus Vasjugania (Acteonidae) is proposed. Eight species are left in the open nomenclature. The protoconch of Siberian Khetella, illustrated here for the first time, suggests that this genus belongs to Purpurinidae and the whole family is a possible stem group for the Neogastropoda. Apart from Khetella the Siberian fauna seems to be of cosmopolitan character having common elements both with Europe and North America.
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Abstract

Research on the chemistry of atmospheric precipitation in the Hornsund region of Svalbard has been extended by analysis of the organic contents. In rainfall samples collected in September 2003, the organics were separated by solid phase extraction (SPE), eluted and analysed on gas chromatograph coupled to a mass selective detector (GC/MS). Rainfall pH was in the range 4.72–5.45, the low values suggesting possible pollution. Concentrations of inorganic ions, expressed as total dissolved salts (TDS), were 5.40–13.18 mg L–1. Non-sea-salt (nss) sulphates were in the range 5–11 μeq L–1. In all samples, long-chain alkanes with chain length up to C36, and their methyl derivatives were detected. Among aromatic compounds biphenyl, dibenzofuran and its methyl derivatives were found. Polycyclic aromatic hydrocarbons (PAHs) were represented by naphthalene, phenanthrene, fluorene, acenaphthene, fluoranthene and pyrene. There were no PAHs with higher numbers of rings. The synoptic meteorological conditions in September 2003 indicate that all organic and inorganic pollutants were of local origin.
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Abstract

The total numbers and biomass of bacterioplankton in two Arctic glacial fjords off west Spitsbergen were studied. Samples were collected from different water depth layers – from the surface to 80–90 m depth. Total bacterial number (TBN), biomass and morphological structure (shape of bacteria) were determined using the acridine orange direct count method. The highest values of TBN and biomass in the water column were found in Kongsfjorden in the stations adjacent to Kongsbreen Glacier, and the lowest values in the outer part of the Krossfjorden. The local maxima of bacterioplankton were observed in water layers around pycnocline. The morphological structure was similar in all samples – the bacteria were dominated by rods (over 65%), followed by cocci (16–20%) and vibrios (11–15%).
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Abstract

Measurements were made of organic fluxes at a coastal sediment at Signy Island , South Orkney Islands, Antarctica , between December 1990 and March 1992. The deposition rate of organic matter to the sediment was measured at the same time with a maximum sedimentation rate of 306 mg C m–2 d–1. The rates of sedimentary organic input were small during winter ice cover, and the organic content of the sediment declined during this period as available organic matter was depleted. Fresh organic input occurred as soon as the sea-ice melted and ice algal biomass was deposited to the sediment; and was sustained during the spring after ice break-up by continued primary production in the water column. The proportion of available carbon in surface sediments was measured during a seasonal cycle using Pseudomonas aeruginosa as an indicator organism over the 0–1 cm depth horizon. Variations in the amount of organic matter deposited to the sediments and the proportion of available carbon were observed during the seasonal cycle. Seasonal variations of benthic activity in this coastal sediment was regulated by the input and availability of organic matter, and not by seasonal water temperature, which was relatively constant between –1.8 and 0.5°C .
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Abstract

The paper presents the results of taxonomical investigation of the genus Cladonia Hill ex P. Browne from King George Island . Individuals belonging to this lichen genus were studied using methods of classical herbarium taxonomy supported by chemical analysis. Fourteen species have been recognized in the study area, with C. asahinae J.W. Thomson being reported from King George Island for the first time, and C. cervicornis subsp. mawsonii reported as new for the South Shetland Islands. The occurrence of C. cariosa is confirmed for the Antarctic region. The diagnostic characters, ecology and important remarks referring to particular species are briefly presented. An updated key for identification of the species from King George Island and neighbouring islands of South Shetlands is included.
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Abstract

The marine psychrophilic and endemic Antarctic yeast Leucosporidium antarcticum strain 171 synthesizes intracellular b-fructofuranosidase, and intra- and extracellular a-glucosidases. Each enzyme is maximally produced at 5°C , while the strain’s optimum growth temperature is 15°C . Invertase biosynthesis appeared regulated by catabolic repression, and induced by sucrose; the enzyme was extremely unstable ex vivo, and only EDTA, Mn2+, and BSA stabilized it for up to 12 h after yeast cell lysis. Thermal stability of the invertase was also low (30 min at temperatures up to 12°C). The optimum temperature for invertase activity was 30°C , and optimum pH was 4.55 to 4.75. The extracellular a-glucosidase was maximally active at 35°C and pH 6.70–7.50, and stable for 30 min up to 20°C.
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Abstract

The shallow water benthic fauna was collected in Kongsfjord, West Spitsbergen. Sampling was conducted along two main environmental gradients: vertical gradient (depth 5–50 m) and horizontal gradient (sedimentation regime) along the fjord axis. A small rectangular dredge was used. Altogether 169 taxa were identified and four macrofaunal associations were distinguished. Bottom type and distance from the tidal glaciers seem to be the main factors responsible for species distribution. The Soft Bottom I Association occupying the fine mud of the Kongsbreen glacial bay consisted mostly of Crustacea with high dominance of scavenging amphipod Onisimus caricus. Bivalves prevailed in the Soft Bottom II Association, located further away from the main glacier outflows. The barren rocky shelf, deprived of vegetation by a sea urchin Strongylocentrotus droebachiensis was inhabited by the Rocky Shelf Association dominated by decapods. The last distinguished association (the Kelp Association) occurred on the hard bottom overgrown with macroalgae. The gastropod Margarites helicinus and amphipods Ischyrocerus spp. made up 60% of the individuals collected there.
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Abstract

During the austral summer of 2002/2003 the author collected 38 marine and/or glacio-marine sediment samples from Admiralty Bay on King George Island (South Shetland Islands, West Antarctica). Recent “living” (Rose Bengal stained) and “dead” (subfossil) benthic foraminifera represented by 105 species belonging to 65 genera are recognized in samples from water depths of up to 520 m. They show large spatial variability. Four distinctive foraminiferal zones within the fjord of Admiralty Bay were recognized and analyzed in terms of environmental conditions. The zones are: restricted coves, open inlets, intermediate-, and deep-waters. The major environmental factors, which dictate foraminiferal distribution, are closely related to bathymetry and distance to open sea. Sediment composition and chlorophyll content appear to have minor influence on foraminiferal communities. Most diverse, deep-water faunas dominate water-depths below 200 m , which seems to be the lowest limit of atmospheric and meltwater influence. In waters shallower than 200 m , environmental features, affecting distribution of various benthic foraminiferal assemblages, appear to be sedimentation rate and hydrographic isolation. The results of this study gives promise to use the Admiralty Bay foraminiferal distribution pattern as a paleoenvironmental tool for shallow- to intermediate-water Quaternary marine research in fjord settings of the South Shetland Islands.
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Abstract

Measurements were made of sediment characteristics, benthic microbial activity and optimum temperature for sulfate reduction at Signy Island, South Orkney Islands, Antarctica . There was little evidence to support any seasonal variation in oxygen penetration of surface sediments. Oxygen penetrated to only 1.5 to 3 mm throughout the year, despite bioturbation from a dense amphipod population. The distribution of acid volatile sulfides increased with depth below 1 cm and above this, surface sediments were lighter in colour and contained fewer sulfides. The rates of sulfate reduction increased during winter under sea-ice cover, and remained high after ice break up. Seasonal water temperature was relatively constant between –1.8 and 0.5°C. Optimum temperature for anaerobic sediment respiration was investigated using different substrates and was found to be in the range 17–27°C, suggesting that sulfate reducing bacteria are psychrotolerant as they were inhibited by low temperatures.
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Abstract

DC resistivity soundings and geomorphological surveys have been carried out in the marginal zones and adjacent outwash plains of two glaciers in central Spitsbergen, Norwegian Arctic: Ebbabreen and Hörbyebreen. The study has revealed complex relationships between landforms, buried glacier ice and permafrost. From this work it is possible to distinguish between moraine ridges which are ice-cored and those which are not. The latter occur in areas which have possibly been affected by glacier surge. The active layer thickness was found to be 0.4 to 2.5 m for diamicton deposits (moraines) and 0.3 to 1.6 m in outwash glacifluvial sediments. The sediment infill thickness in valleys was determined to be as much as 20 m, thereby demonstrating that sandurs have important role in sediment storage in a glacial system. Typical resistivity values for sediment types in both the active layer and in permafrost were also determined.
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Abstract

Fjords of West Spitsbergen are very dynamic in terms of hydrology. Here we tested whether the qualitative analysis of the taxonomic composition of phytoplankton may be useful as a fast method to assess the origin of the waters and whether it can give any additional information to hydrological data. Phytoplankton samples were collected along transects in Hornsund and Kongsfjord. Among total of 109 taxa identified, only 49 were common in both fjords. The assemblages in Hornsund implied that inflow of the cold waters of the Sřrkapp Current had occurred some time before samples collection, while in Kongsfjord the taxonomic composition was typical for the summer and did not show any recent, unusual hydrological phenomenon. Concluding, the method can be useful in the surveys in which hydrological data are collected infrequently.
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Abstract

During the 2004 summer season, 14 sediment samples were collected in Kongsfjorden and Isfjorden, West Spitsbergen, from 6 down to 345 m water-depth (mwd). The samples yielded abundant assemblage of monothalamous foraminifera, belonging to almost 40 morphotypes. Our qualitative (>125 um) and quantitative data (125-500 um) allowed to distinguish three water-depth related assemblages in both Kongsfjorden and Adventfjorden (branch of Isfjorden), indicating that soft-walled monothalamous foraminifera show similar habitat gradation along fjord axis as calcareous and robust agglutinated taxa. Among the monothalamous foraminifera, the subtidal assemblage (6 mwd) was dominated by various unidentified allogromiids. The second, shallow-water assemblage (44-110 mwd) was dominated by Psammophaga sp. 1-3, Hippocrepinella crassa, Hippocrepinella cf. hirudinea, and large Gloiogullmia sp. 2. The deep-water (150-345 mwd) monothalamous assemblage was dominated by Psammophaga sp. 4, pear-shaped Hippocrepina sp., Hippocrepina indivisa, and long Cylindrogullmia sp. 2, as well as large agglutinated species Hyperammina subnodosa with attached Tholosina bulla, Hyperammina fragilis and Lagenammina sp.
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Abstract

Intertidal zone of four gravel beaches in Hornsund Fjord (West Spitsbergen) were investigated in order to study macrofaunal distribution and diversity in these poor habitats. A total of 12 macrofaunal taxa were found in the collected material. The most frequent and the most abundant taxon was Lumbricillus sp. (Oligochaeta). The next most numerous group were juvenile Gammarus spp. juv. The fauna included also polychaetes, molluscs and other crustaceans. The diversity measured with Shannon-Weaver index was low and varied from 0 to 1.4. The analysis revealed that there were no statistically important differences in macrofaunal distribution among stations in fjord. However there were significant differences among various tidal mark zones and high patchiness in animals abundance at each station. Also species composition, density and biomass were diversified along the tide level profile.
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Abstract

Trace metal composition of snowpack, snow-melt filter residues and top-soils were determined along transects through industrial towns in the Usa River Basin: Inta, Usinsk and Vorkuta. Elevated concentrations of deposition elements and pH in snow and soils associated with alkaline coal ash within 25-40 km of Vorkuta and Inta were found. Atmospheric deposition in the vicinity of Vorkuta and Inta, added significantly to the soil contaminant loading as a result of ash fallout. The element concentrations in soils within 20-30 km of Vorkuta do not reflect current deposition rates, but instead, reflect an historical pollution legacy, when coal mining activity peaked in the 1960s. There is little evidence of anthropogenic metal deposition around the gas and oil town of Usinsk.
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Abstract

The infections of four fish species, Trematomus newnesi, T. bernacchii, Lindbergichthys nudifrons and Harpagifer antarcticus with parasitic worms, in the coastal zone off the Vernadsky Station (Argentine Islands, West Antarctica) are described. Data on infections are compared with previous results from Admiralty Bay at the South Shetland Islands. Indices of infection are for each host-parasite relationship. In total, 16 taxa of parasites were recorded: 6 digeneans, 3 larval cestodes, 4 (adult and cystacanth) acanthocephalans, and 3 (adult and larval) nematodes. Fifteen of them have been previously recorded in Notothenia coriiceps from this area. Hence, the number of parasitic taxa recorded in this region increased from 21 to 22. Either the digenean Macvicaria georgiana or acanthocephalan Corynosoma pseudohamanni were dominants in different hosts. Trematomus bernacchii was the most strongly infected, especially with M. georgiana (prevalence 100%, mean abundance 113.7). The infection parameters of the majority of parasites were lower at the Vernadsky Station than in the Admiralty Bay, especially for host-parasite relations with larval cestodes and nematodes. The presently reported study have confirmed that the southern range of distribution of two acanthocephalans, Aspersentis megarhynchus and Corynosoma hamanni extends south to the area near the Argentine Islands.
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Abstract

The electrical impedance diagnostic methods and instrumentation developed at the Gdansk and Warsaw Universities of Technology are described. On the basis of knowledge of their features, several original approaches to the broad field of electrical impedance applications are discussed. Analysis of electrical field distribution after external excitation, including electrode impedance, is of primary importance for measurement accuracy and determining the properties of the structures tested. Firstly, the problem of electrical tissue properties is discussed. Particular cells are specified for in vitro and in vivo measurements and for impedance spectrometry. Of especial importance are the findings concerning the electrical properties of breast cancer, muscle anisotropy and the properties of heart tissue and flowing blood. The applications are both important and wide-ranging but, for the present, special attention has been focused on the evaluation of cardiosurgical interventions. Secondly, methods of instrument construction are presented which use an electrical change in conductance, such as impedance pletysmography and cardiography, for the examination of total systemic blood flow. A new method for the study of right pulmonary artery blood flow is also introduced. The basic applications cover examination of the mechanical activity of the heart and evaluation of many haemodynamic parameters related to this. Understanding the features that occur during blood flow is of major importance for the proper interpretation of measurement data. Thirdly, the development of electrical impedance tomography (EIT) is traced for the purposes of determining the internal structure of organs within the broad field of 2-D and 3-D analysis and including modelling of the organs being tested, the development of reconstruction algorithms and the construction of hardware.
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Abstract

The paper presents the results of a numerical study devoted to the hydraulic properties of a network of parallel triangular microchannels (hydraulic diameter Dh = 110 um). Previous experimental investigations had revealed that pressure drop through the microchannels system dramatically increases for the Reynolds number exceeding value of 10. The disagreement of the experimental findings with the estimations of flow resistance based on the assumption of fully developed flow were suspected to result from the so-called scale effect. Numerical simulations were performed by using the classical system of flow equations (continuity and Navier-Stokes equations) in order to explain the observed discrepancies. The calculations showed a very good agreement with the experimental results proving that there is no scale effect for the microchannels considered, i.e. the relevance of the constitutive flow model applied was confirmed. It was also clearly indicated that the excessive pressure losses in the high Reynolds number range are due to the secondary flows and separations appearing in several regions of the microchannel system.
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Abstract

A review is given on a number of colloidal phenomena with special reference to their applicability to nanoparticles. Phenomena addressed include preparation, electric double layers and their characterization, electrokinetics, van der Waals and Lifshits forces, electric and steric particle interaction.
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Abstract

In this simulation study, we used an anatomical computer model of the human ventricles to simulate body surface potentials and magnetic field for 10 single preexcitation sites and 8 pairs of preexcitation sites positioned on the epicardial surface along the atrio-ventricular ring. We demonstrated that electrocardiographic and magnetocardiographic inverse solutions using a pair of equivalent dipoles could be employed in localising dual accessory pathways. Average localisation errors were in the range of 5 to 21 mm and 3 mm to 20 mm, respectively, when body surface potentials and magnetic field were used. Additionally, we have investigated the influence of random lead displacements and limited lead selection on localisation results.
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Abstract

The paper describes the research on soft X-ray lasers with an active medium created using a gas puff target irradiated with high-intensity laser pulses. The gas puff target in a form of an elongated gas sheet is produced by pulsed injection of gas through a slit nozzle using a high-pressure electromagnetic valve. The method of generation of soft X-ray lasers using a laser-irradiated gas puff target has been developed at the Institute of Optoelectronics. The collaborative experiments were performed at various laser laboratories using high-intensity laser systems to irradiate the gas puff target and pump the X-ray laser active medium. Results of these experiments are presented and discussed. Works aimed at increasing the efficiency of X-ray lasers using a longitudinally irradiated gas puff target are also reviewed.
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