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  • 1
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    Pleistocene freshwater ostracods from the Homo erectus site at Bilzingsleben, Germany—Review of historic collection and unpublished manuscript material for palaeoenvironmental reconstruction (2023)
    Details
    Publication Date: 2023-07-25
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉We provide a review of micropalaeontological research on Ostracoda from the Middle Pleistocene (MIS 11, Holstein interglacial) hominin site Bilzingsleben in Thuringia in Central Germany from 1963 to the 1990s. Samples from four sections inside and six search pits outside the excavation area were investigated and, in total, 49 ostracod species were identified. The ostracod assemblages of the sections mirror the complex and small‐scale palaeoenvironmental evolution of the site from a seeping‐spring to fluviatile, lacustrine and finally seeping‐spring habitat in which a massive tufa layer formed and prevented erosion of the sediments beneath. Pleistocene index fossils are represented by 〈italic〉Ilyocypris quinculminata〈/italic〉 from search pit 3/sample 9933 and 〈italic〉Scottia browniana〈/italic〉 from section 70. Both species indicate the age dating of MIS 11 for the tufa deposit. The results of this study facilitate new insights into site formation processes, enable refinement of the interpretation of the archaeological record and shed light on the question: Does the find‐bearing layer at the Bilzingsleben site contain in situ remains of a camp site of 〈italic〉Homo erectus〈/italic〉 or not? Our results suggest that the site is not unaffected at least.〈/p〉
    Description: Free State of Thuringia
    Keywords: ddc:565 ; actualistic approach ; Holstein interglacial ; Ostracoda ; palaeo air temperature ; palaeosalinity ; tufa
    Language: English
    Type: doc-type:article
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    CITATION GEO-LEO
  • 2
    Electronic Resource
    Electronic Resource
    Vinylidene transition-metal complexes. XXIII. Insertion of a vinylidene unit into a ruthenium-oxygen bond: synthesis and molecular structure of [cyclic] [C5H5(PPh3)RuC(:CHCO2Me)OC(Me)O] (1993)
    s.l. : American Chemical Society
    Organometallics 12 (1993), S. 1475-1477 
    Details
    ISSN: 1520-6041
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/om00028a080
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  • 3
    Electronic Resource
    Electronic Resource
    New synthetic routes to azavinylidene half-sandwich type complexes (1991)
    s.l. : American Chemical Society
    Inorganic chemistry 30 (1991), S. 3118-3120 
    Details
    ISSN: 1520-510X
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ic00016a004
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  • 4
    Electronic Resource
    Electronic Resource
    Endothelial Signal Integration in Vascular Assembly (2000)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Physiology 62 (2000), S. 649-671 
    Details
    ISSN: 0066-4278
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Medicine , Biology
    Notes: Abstract Regulated assembly of a highly specialized interconnecting network of vascular endothelial and supportive cells is fundamental to embryonic development and organogenesis, as well as to postnatal tissue repair in metazoans. This review advances an "endotheliocentric" model that defines tasks required of endothelial cells and describes molecular controls that regulate steps in activation, assembly, and maturation of new vessels. In addition to the classical assembly mechanisms-angiogenesis and vasculogenesis-endothelial cells are also recruited into vascular structures from the circulatory system in adult animals and from resident mesenchymally derived progenitors during organogenesis of kidney and other organs. Paracrine signaling cascades regulated by hypoxia initiate a sequentially coordinated series of endothelial responses, including matrix degradation, migration, proliferation, and morphogenetic remodeling. Surface receptors on committed endothelial lineage progenitors transduce cues from extracellular-matrix-associated proteins and cell-cell contact to direct migration, matrix attachment, proliferation, targeting and cell-cell assembly, and vessel maturation. Through their capacity to spatially segregate and temporally integrate a diverse range of extracellular signals, endothelial cells determine their migratory paths, cellular partners, and life-or-death responses to local cues.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.physiol.62.1.649
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  • 5
    Electronic Resource
    Electronic Resource
    Exceptionally stable phenyldichlorocarbenium ion as a Friedel-Crafts intermediate: a high-field multinuclear NMR study (1989)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 111 (1989), S. 7659-7661 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja00201a081
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  • 6
    Electronic Resource
    Electronic Resource
    Mechanical determinants of nectar feeding strategy in hummingbirds: energetics, tongue morphology, and licking behavior (1983)
    Springer
    Oecologia 60 (1983), S. 214-226 
    Details
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary To explore the mechanical determinants of feeding strategies for nectar feeders, we develop a fluid dynamical and behavioral model describing the mechanics and energetics of capillary feeding in hummingbirds. Behavioral and morphological data for Calypte and Archilochus are used to test and illustrate this model. We emphasize the important differences between capillary and suction mechanisms of fluid feeding. Model predictions of nectar intake rates and nectar volumes per lick are consistent with observed values for Calypte anna. The optimal nectar concentration maximizing rate of energy intake depends on tongue morphology and licking behavior. For hummingbirds exhibiting optimal licking behavior, the optimal nectar concentration is 35–40% sucrose for feeding on large nectar volumes. For small nectar volumes, the optimal concentration is 20–25%. The model also identifies certain tongue morphologies and licking frequencies maximizing energy intake, that are consistent with available observations on licking behavior and tongue design in nectar feeding birds. These predictions differ qualitatively from previous results for suction feeding in butterflies. The model predicts that there is a critical food canal radius above which suction feeding is superior to capillary feeding in maximizing the rate of energy intake; the tongues of most hummingbirds and sunbirds fall above this critical radius. The development of suction feeding by nectarivorous birds may be constrained by the elastic properties of their flexible tongues. Our results show that, in terms of morphology, scaling, and energetics, different mechanisms of feeding on the same food resource can lead to qualitatively different predictions about optimal design and feeding strategies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00379523
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  • 7
    Electronic Resource
    Electronic Resource
    Long-term variation in seawater composition at the base of the thermocline (1988)
    [s.l.] : Nature Publishing Group
    Nature 332 (1988), S. 714-717 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The most detailed long-term record of seawater chemistry known to the authors is the Panulirus Station 4S' data set, collected by the Bermuda Biological Station from south of Bermuda at monthly intervals from 1952 to the present1. Although this record has proved valuable in many oceano-graphic ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/332714a0
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  • 8
    Electronic Resource
    Electronic Resource
    Mechanical determinants of nectar-feeding energetics in butterflies: muscle mechanics, feeding geometry, and functional equivalence (1989)
    Springer
    Oecologia 79 (1989), S. 66-75 
    Details
    ISSN: 1432-1939
    Keywords: Pieris ; Nectivory ; Optimal foraging ; Muscle mechanics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We develop a mechanistic model for nectar feeding in butterflies that integrates the two basic components of the feeding process: the fluid dynamics of nectar flow through the food canal and the contractile mechanics of the muscular, cibarial pump. We use the model to predict the relation between rate of energy intake during feeding and nectar concentration. We then identify nectar concentations that maximize energy intake rates (the optimal concentrations). We illustrate the model using measurements of the food canal and cibarium of Pieris butterflies. The model predicts an overall optimal range of nectar concentration of 31–39% sucrose for butterflies, which is in agreement with previously reported laboratory values. The model also predicts an interaction among the geometries of the food canal, the cibarial cavity, and the cibarial muscles, that allows us to identify the combinations of food canal, cibarium, and muscle dimensions that yield the highest rates of energy intake. Nectar-feeding is “functionally equivalent” in butterflies and hummingbirds: two physically different feeding mechanisms can yield identical energy intake rates. This equivalence results from a mathematical and physical similarity between quasi-steady-state fluid flow in hummingbrid tongues and the force-velocity characteristics of contracting cibarial muscle in butterflies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00378241
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  • 9
    Electronic Resource
    Electronic Resource
    Myotendinous junctions of tonic muscle cells: structure and loading (1986)
    Springer
    Cell & tissue research 245 (1986), S. 315-322 
    Details
    ISSN: 1432-0878
    Keywords: Skeletal muscle ; Myotendinous junctions ; Membrane ; Morphometry ; Frog (Rana pipiens)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Regions within frog semitendinosus muscle that are rich in tonic muscle cells were identified histochemically by myosin adenosine triphosphatase- and succinic dehydrogenase-staining procedures. Bundles of cells still attached to tendinous insertions were removed from those sites, prepared for electron microscopy and sectioned longitudinally through their myotendinous junctions. Tonic cells were identified by electron-microscopic criteria and their myotendinous junctions' morphology evaluated by morphometry. Although junctional components appear identical to those in twitch cells, the degree of membrane folding increases tonic junction area by a factor of 50.2 whereas twitch cells' junctional area is increased 22.2 times by folding relative to cells terminating as right circular cylinders. Calculations show that the tonic cell junction bears average loads of 3.4×103 N · m-2 during maximum force generation and that nearly all of the load is borne as shear stress at the junction. The junctions of twitch cells bear average loads of 1.6×104 N · m-2 during peak tension. The findings indicate that the magnitude of loading does not alone determine the degree of junctional membrane folding. Interpretation of the data in view of viscoelastic behavior of membranes indicates that duration of loading may be a functionally important correlate to degree of membrane folding at myotendinous junctions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00213937
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  • 10
    Electronic Resource
    Electronic Resource
    Norbornadiene(bipyridyl)molybdenum(II) Complexes: Synthesis, Structure and Reactivity of [Mo(CO)(C7H8)(C10H6R2N2)X2] (X = I, Br)Dedicated to Professor Dr. Helmut Werner on the occasion of his birthday. (1995)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 128 (1995), S. 1007-1013 
    Details
    ISSN: 0009-2940
    Keywords: Tetracarbonyl(norbornadiene)molybdenum(0) ; Oxidative addition of I2 ; Dihalogeno(bipyridyl)molybdenum(II) complexes ; 7-Coordinated complexes ; Neutral and cationic molybdenum(II) complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of [Mo(CO)4(C7H8)] (1) with I2 gave the norbornadienemolybdenum(II) complex [Mo(CO)2(C7H8)I2]n≥1 (2), which existed in an equilibrium of two isomeric forms. In acetonitrile, 2 reversibly formed the adduct [Mo(CO)2-(C7H8)(NCCH3)I2] (3), whereas on treatment with 2,2′-bipyridine or 4,4′-di-2,2′-tBu-bipyridine, it gave stable 7-coordinated molybdenum(II) complexes, [Mo(CO)(C7H8)-(C10H8N2)I2] (4) and [Mo(CO)(C7H8)(C10H6tBu2N2)I2] (5), in good yield. In similar reactions, the related dibromomolybdenum compounds [Mo(CO)(C7H8)(C10H8N2)Br2] (6) and [Mo-(CO)(C7H8)(C10H6tBu2N2)Br2] (7) were prepared by oxidation of 1 with two equivalents of CuBr2. The X-ray structural analysis of 6 reveals that the geometry around the molybdenum atom is nearly perfectly pentagonal bipyramidal, with the CO and one of the bipyridyl rings perpendicular to the plane formed by the other ligands. The compounds 5 and 6 react with AgSbF6 by halogen abstraction to give cationic complexes, {[Mo(CO)(C7H8)(C10H8N2)Br]SbF6}n≥1 (8) and {[Mo(CO)(C7H8)(C10H6tBu2N2)I]SbF6}n≥1 (9): In acetone, 8 and 9 reversibly formed the adducts [Mo(CO)(C7H8)(C10H8N2)(acetone)Br]SbF6 (8′) and [Mo(CO)(C7H8)(C10H6tBu2N2)(acetone)I]SbF6 (9′); while on treatment with PMe3, the stable monomeric complexes, [Mo(CO)(C7H8)(C10H8N2)(PMe3)Br]SbF6 (10) and [Mo(CO)(C7H8)(C10H6tBu2N2)(PMe3)I]SbF6 (11), were isolated in almost quantitative yield. In the presence of KBr, compound 8′ reverted to the dibromo complex 6, whereas 9′ reacted to produce a 1:1:2 mixture of 5, 7 and the bromo(iodo) complex [Mo(CO)(C7H8)(C10H6tBu2N2)BrI] (12). The same mixture is available from the reaction of 5 with one equivalent of 7.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19951281008
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