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  • 1
    Electronic Resource
    Electronic Resource
    The Dead Sea — alive again (1993)
    Springer
    Cellular and molecular life sciences 49 (1993), S. 518-522 
    Details
    ISSN: 1420-9071
    Keywords: Dead Sea ; Halobacteriaceae ; Dunaliella
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract In the thirteen years of quantitative studies on the microbiology of the Dead Sea from 1980 onwards three distinct periods can be discerned. Mass development of the green unicellular algaDunaliella parva (up to 8,800 cells/ml) and red archaeobacteria (2×107 cells/ml) was observed in 1980, following a dilution of the upper water layers by rain floods. This bloom disappeared at the end of 1982 as a result of a complete mixing of the water column. During the period 1983–1991 the lake was holomictic, and noDunaliella cells were observed. Viable bacteria were present during this period in very low numbers. Heavy rain floods during the winter of 1991–1992 caused a new stratification as the upper five meters of the water column became diluted to 70% of their normal salinity. In this upper water layerDunaliella reappeared (up to 3×104 cells/ml at the beginning of May, rapidly declining to less than 40 cells/ml at the end of July), and a bloom of red archaeobacteria (3×107 cells/ml) once more imparted a red coloration to the lake.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01955154
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  • 2
    Electronic Resource
    Electronic Resource
    The complexity of resource allocation and price mechanisms under bounded rationality (1995)
    Springer
    Economic theory 6 (1995), S. 225-250 
    Details
    ISSN: 1432-0479
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Summary We develop a framework for designing and evaluating the complexity of mechanisms that allocate resources in a distributed setting to agents or processors with bounded computational ability. We discuss several mechanisms and describe the construction of efficient price based mechanisms, which exploit the decentralized aspects of the problem. These price mechanisms are polynomial in the number of resources, precision of the solution, and the logarithm of the number of agents.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01212489
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  • 3
    Electronic Resource
    Electronic Resource
    Results of the UNDP (SF)/FAO Regional Fisheries Survey in West Africa. report No. 2. Preliminary note on dissolved oxygen in the Canary Current (1972)
    Springer
    Marine biology 17 (1972), S. 1-3 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract While examining historical data on dissolved oxygen in the Canary Current area and the Central Atlantic Ocean (areas of activity of the UNDP/FAO Regional Fisheries Survey in West Africa), a quite different pattern of distribution was found in the dissolved oxygen/water temperature relationship in two adjacent Marsden squares (MS)1, 074 and 038. Not only were the dissolved oxygen values in MS 038 considerably lower than in MS 074 but, in the former square, the oxgen/temperature distribution showed 2 dissolved oxygen minima, the latter only 1 minimum. In MS 335, situated below the Equator, near the African coast, the oxygen/temperature distribution differs from the two former squares in that the dissolved oxygen value decreased steadily, and no oxygen minimum was found down to a depth where the water temperature was 6°C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00346949
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  • 4
    Electronic Resource
    Electronic Resource
    Transplantation of juvenile corals: a new approach for enhancing colonization of artificial reefs (1997)
    Springer
    Marine biology 127 (1997), S. 499-505 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Coral reefs in the northern Gulf of Eilat are exposed to continuous man-made disturbances, resulting in decreased coral coverage and reduced recruitment at the Nature Reserve of Eilat. The construction of artificial reefs on sandy bottoms is a possible option to decrease diving pressure on natural reefs. In the present study we tested this hypothesis by submerging an experimental artificial reef anchored to the bottom at 18 m depth and floated vertically 3 m below water surface. The reef was composed of PVC plates, attached both vertically and horizontally along a wire. Propagules of two coral species, the stony coral Stylophora pistillata and the soft coral Dendronephthya hemprichi, were transplanted to this artificial reef. Planulae of S. pistillata were obtained during the breeding season, seeded in petri dishes in the laboratory and after 2 wk the dishes were transferred to the experimental artificial reef. Automized fragments of D. hemprichi which had previously settled on 10 × 10 cm PVC plates were transplanted onto the experimental artificial reef. The survivorship of the transplanted D. hemprichi colonies was significantly higher on the lower sides of shallower plates. Survivorship of S. pistillata colonies increased with depth when located on the vertical plates, or on the upper sides of the horizontal plates. The highest survivorship of this coral was on the vertical plates and on the upper sides of the horizontal plates, while very low survivorship was recorded on the lower sides. The results indicate that vertical artificial surfaces offer the optimal biotic and abiotic conditions for the survival of the two examined corals. The vertical plates are characterized by low sed imentation rates, low coverage of turf-algae, minimal grazing by sea urchins and absence of the competitor tunicate Didemnum sp. In addition, the vertical orientation of the experimental plates reduces shading and offers the required light intensity for zooxanthellate corals such as S. pistillata. Only a few studies to date have tried to implement artificial reefs in a coral reef environment. The results of the present study indicate the potential of enhancing recruitment of corals by transplantation of juvenile recruits onto appropriate artificial structures. Maximal survivorship of these recruits is dependent upon the structural features of the artificial reef, which should offer optimal conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002270050038
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  • 5
    Electronic Resource
    Electronic Resource
    International Biological Programme: Co-ordinated studies on grey mullets (1971)
    Springer
    Marine biology 10 (1971), S. 30-33 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The International Biological Programme/Marine Productivity Section (IBP/PM) initiated cooperation in world-wide studies on the grey mullet; grey mulltests are of great economic importance in many places in the world, but mainly in the tropical and subtropical regions. The aim of IBP/PM is the intensification of studies and the use of lagoons and estuaries for fish production. The importance of the mullet lies also in the fact that it is a detritus feeder, a fast growing fish, and can be successfully bred under artificial conditions. To make cultivation of these fish economical and independent of natural supply (which is becoming ever more unreliable through pollution of laggons and coastal waters), the life cycle of these fish has to be completed and the problem of induced spawning solved. Such investigations are underway in several laboratories in the World. Dissemination of the knowledge acquired, accumulation of experience on this subject, and eventual use of the results as models for induced spawning and cultivation of other species of fish and invertebrates, is another aim of IBP/PM.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02026763
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  • 6
    Electronic Resource
    Electronic Resource
    Results of the UNDP(SF)/FAO Regional Fisheries Survey in West africa. Report no 3. Silicates in the Canary Current area (1972)
    Springer
    Marine biology 17 (1972), S. 4-6 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Canary Current region off West Africa was examined for its temperature, salinity and dissolved oxygen relations. When historical data on dissolved silicate were examined in the same area, it was found that the area of intensive upwelling has the least amounts of silicate compared with adjacent regions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00346950
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  • 7
    Electronic Resource
    Electronic Resource
    Results of the UNDP (SF)/FAO regional fisheries survey in West Africa. Report no. 4. T/S relationship in the Canary Current area (1972)
    Springer
    Marine biology 17 (1972), S. 187-200 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Based on historical oceanographic data supplied by the National Oceanographic Data Center (NODC), Washington, D.C., USA, temperature salinity (T/S) diagrams were drawn for a large number of one-degree squares within marsden Squares (MS) 074, 038 and the northern half of MS 002. The shelf area of these squares was the area of the Regional Fisheries Survey activities in 1969 and 1970. The aim of the work is to illustrate the different characteristics of the water in the area. It is shown, in a set of diagrams, that the northern part of MS 074 contains nearly pure North Atlantic Central Water (NACW), except for the surface layer, where the characteristics change with season. In the upwelling area of Senegambia, during the upwelling season, the water is of a South Atlantic Central Water (SACW) and NACW mixed type, while in the offshore area it is nearly pure NACW. In the southern part of MS 074 and the northern part of MS 038, the subsurface water is a mixture of NACW and SACW, which changes into pure SACW southwards, but remains a mixture in medium depths. The SACW is always superimposed on the NACW. Inshore, the water mass changes with season. During the rainy season this is Liberian surface water of low salinity and high temperature. In MS 002, to the south, offshore, the subsurface water becomes pure SACW, which in deep parts overlays the Antarctic Water. Inshore at the surface, the water is desalinated during the rainy season. The Liberian surface water spreads over the whole of MS 002, nearly 1000 miles offshore.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00366293
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  • 8
    Electronic Resource
    Electronic Resource
    Thymidine incorporation in saltern ponds of different salinities: Estimation of in situ growth rates of halophilic archaeobacteria and eubacteria (1990)
    Springer
    Microbial ecology 19 (1990), S. 43-51 
    Details
    ISSN: 1432-184X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Incorporation of [methyl-3H]thymidine was measured in solar saltern ponds of different salinities. Estimated doubling times of the bacterial communities were in the range of 1.1 to 22.6 days. Even at the highest salt concentrations (NaCl saturation), relatively rapid thymidine incorporation was observed. In an attempt to differentiate between activity of halophilic archaeobacteria (theHalobacterium group) and halophilic eubacteria, taurocholate, which causes lysis of the halobacteria without affecting eubacteria, was used. At salt concentrations exceeding 250 g/liter all thymidine incorporation activity could be attributed to halobacteria. Aphidicolin, a potent inhibitor of DNA synthesis in halobacteria, completely abolished thymidine incorporation at the highest salinities, but also caused significant inhibition at salinities at which halobacteria are expected to be absent. Attempts to use nalidixic acid to selectively inhibit DNA synthesis by the eubacterial communities were unsuccessful.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02015052
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  • 9
    Electronic Resource
    Electronic Resource
    Dynamic Diversification from a Putative Common Ancestor of Scorpion Toxins Affecting Sodium, Potassium, and Chloride Channels (1999)
    Springer
    Journal of molecular evolution 48 (1999), S. 187-196 
    Details
    ISSN: 1432-1432
    Keywords: Key words: Gene organization — Scorpion neurotoxins — Ion channels — Common progenitor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. Scorpions have survived successfully over millions of years without detectable changes in their morphology. Instead, they have developed an efficient alomonal machinery and a stinging device supporting their needs for prey and defense. They produce a large variety of polypeptidic toxins that bind and modulate ion channel conductance in excitable tissues. The binding site, mode of action, and chemical properties of many toxins have been studied extensively, but little is known about their genomic organization and diversity. Genes representing each of the major classes of Buthidae scorpion toxins, namely, ``long'' toxins, affecting sodium channels (alpha, depressant, and excitatory), and ``short'' toxins, affecting potassium and chloride channels, were isolated from a single scorpion segment and analyzed. Each toxin type was found to be encoded by a gene family. Regardless of toxin length, 3-D structure, and site of action, all genes contain A+T-rich introns that split, at a conserved location, an amino acid codon of the signal sequence. The introns vary in length and sequence but display identical boundaries, agree with the GT/AG splice junctions, and contain T-runs downstream of a putative branch point, 5′-TAAT-3′. Despite little sequence similarity among all toxin classes, the conserved gene organization, intron features, and common cysteine-stabilized α-helical (CSH) core connecting an α-helix to a three-stranded β-sheet suggest, that they all evolved from an ancestral common progenitor. Furthermore, the vast diversity found among genomic copies, cDNAs, and their protein products for each toxin suggests an extensive evolutionary process of the scorpion ``pharmaceutical factory,'' whose success is due, most likely, to the inherent permissiveness of the toxin exterior to structural alterations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00006457
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  • 10
    Electronic Resource
    Electronic Resource
    Definitions and properties of zero-knowledge proof systems (1994)
    Springer
    Journal of cryptology 7 (1994), S. 1-32 
    Details
    ISSN: 1432-1378
    Keywords: Zero-knowledge ; Computational complexity ; Computational indistinguishability ; Cryptographic composition of protocols
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract In this paper we investigate some properties of zero-knowledge proofs, a notion introduced by Goldwasser, Micali, and Rackoff. We introduce and classify two definitions of zero-knowledge: auxiliary-input zero-knowledge and blackbox-simulation zero-knowledge. We explain why auxiliary-input zero-knowledge is a definition more suitable for cryptographic applications than the original [GMR1] definition. In particular, we show that any protocol solely composed of subprotocols which are auxiliary-input zero-knowledge is itself auxiliary-input zero-knowledge. We show that blackbox-simulation zero-knowledge implies auxiliary-input zero-knowledge (which in turn implies the [GMR1] definition). We argue that all known zero-knowledge proofs are in fact blackbox-simulation zero-knowledge (i.e., we proved zero-knowledge using blackbox-simulation of the verifier). As a result, all known zero-knowledge proof systems are shown to be auxiliary-input zero-knowledge and can be used for cryptographic applications such as those in [GMW2]. We demonstrate the triviality of certain classes of zero-knowledge proof systems, in the sense that only languages in BPP have zero-knowledge proofs of these classes. In particular, we show that any language having a Las Vegas zero-knowledge proof system necessarily belongs to RP. We show that randomness of both the verifier and the prover, and nontriviality of the interaction are essential properties of (nontrivial) auxiliary-input zero-knowledge proofs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00195207
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