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  • 1
    Electronic Resource
    Electronic Resource
    Regular Polytopes in Ordinary Space (1997)
    Springer
    Discrete & computational geometry 17 (1997), S. 449-478 
    Details
    ISSN: 1432-0444
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract. The three aims of this paper are to obtain the proof by Dress of the completeness of the enumeration of the Grünbaum—Dress polyhedra (that is, the regular apeirohedra, or apeirotopes of rank 3) in ordinary space E 3 in a quicker and more perspicuous way, to give presentations of those of their symmetry groups which are affinely irreducible, and to describe all the discrete regular apeirotopes of rank 4 in E 3 . The paper gives a complete classification of the discrete regular polytopes in ordinary space.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00009304
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  • 2
    Electronic Resource
    Electronic Resource
    Geometric realizations for Dyck's regular map on a surface of genus 3 (1986)
    Springer
    Discrete & computational geometry 1 (1986), S. 141-153 
    Details
    ISSN: 1432-0444
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract Klein's and Dyck's regular maps on Riemann surfaces of genus 3 were one impetus for the theory of regular maps, automorphic functions, and algebraic curves. Recently a polyhedral realization inE 3 of Klein's map was discovered [18], thereby underlining the strong analogy to the icosahedron. In this paper we show that Dyck's map can be realized inE 3 as a polyhedron of Kepler-Poinsot-type, i.e., with maximal symmetry and minimal self-intersections. Furthermore some closely related polyhedra and a Kepler-Poinsot-type realization of Sherk's regular map of genus 5 are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02187691
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  • 3
    Electronic Resource
    Electronic Resource
    Influence of algal concentration and temperature on the filtration rate of Mytilus edulis (1975)
    Springer
    Marine biology 30 (1975), S. 331-341 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The filtration rates of Mytilus edilis (=galloprovincialis; 40 mm) were determined in relation to food concentration and temperature, using pure suspensions of the unicellular alga Platymonas suecica in concentrations ranging from 3x105 cells/l to 1.5x108 cells/l. The rate of filtration (ml/h/mussel) generally decreased as cell concentrations increased, and dropped to low values when concentrations above 5x107 cells/l were supplied. The amount of water swept clear varied continuously, and noticeable differences in the filtration activity of M. edulis were observed over short time intervals (5 min). Fluctuations of filtered volumes per unit time were greater with lower than with higher concentrations of algae. The influence of temperature on filtration activity was highest between 5°–15°C and 25°–30°C. A temperature increase from 15° to 25°C resulted in only a slight increase in filtration rate. At 5° and 30°C, filtration dropped to very low values, namely 350 and 100 ml/h, respectively. The temperature coefficients for the filtration rates of M. edulis were determined as: Q10 (5° to 15°C)=4.96; Q10 (10° to 20°C)=1.22. The amount of algae cells ingested per mussel per hour is directly related to food concentration. The maximum number of cells filtered/mussel/h in an algal suspension of 70x106 cells/l was 21.5x105 cells/h. Cell concentrations of up to 40x106 cells/l were swept clear without producing pseudofaeces. The critical cell density for M. edulis was reached at algal concentrations of 70 to 80x106 cells/l. Above these concentrations no normal filtration activity was observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00390638
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  • 4
    Electronic Resource
    Electronic Resource
    Feinstruktur des Trichterepithels von Rhinomuraena ambonensis (Teleostei, Anguilliformes) (1971)
    Springer
    Marine biology 11 (1971), S. 61-76 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung 1. Die vorliegende Untersuchung behandelt die Feinstruktur der Nasentrichter von Rhinomuraena ambonensis. 2. Die Trichterwand zeigt einen symmetrischen Aufbau, an dem ein Innenepithel, ein Außenepithel und ein dazwischenliegendes Bindegewebe beteiligt sind. 3. Jede äußere Epithelzelle bildet nach außen ein Mikroleistennetz, das nicht mit dem der Nachbarzellen korrespondiert. 4. Die geradlinigen epithelialen Zellgrenzen sind durch zahlreiche Desmosomen verbunden, auf deren Feinbau näher eingegangen wird. 5. Mit zunehmender Entfernung von der Epitheloberfläche vergrößert sich die Anzahl und die Ausdehnung der Interzellularspalten. Sie werden als Turgorstruktur zur Organversteifung der Nasentrichter gedeutet. 6. Jede Epithelzelle läßt unter der äußeren Zellmembran eine ausgedehnte Tonofibrillenzone erkennen von der aus Tonofibrillenbündel zu den Desmosomen ziehen. 7. Zwischen den Epithelzellen sind Sekretzellen und einzelne Sinnesknospen eingebettet, deren Feinbau behandelt wird. 8. Der innere Abschluß des Trichterepithels wird von einer auffallend dicken Basalmembran gebildet. 9. Im Bindegewebe liegen zahlreiche Gefäße, Nervenfaserbündel, sowie vereinzelt Pigmentzellen und Speicherzellen mit kristallinen Einschlüssen. 10. Die Bedeutung der Desmosomen, Tonofilamente, Interzellularräume, wie auch der verhältnismäßig dicken Basalmembran und des großen Kollagengehaltes im Bindegewebe wird diskutiert im Hinblick auf die Formbeständigkeit der Trichter durch eine permanente Versteifung.
    Notes: Abstract The ultrastructure of the funnel-like tubes of the olfactory organ in Rhinomuraena ambonensis was investigated by electron microscopy. Frontal sections of the tubes demonstrate a symmetrical arrangement of an inner epithelium, connective tissue, and an outer epithelium. The surface of each peripheral cell of the epithelia bears a system of small ridges which does not correspond with that of the adjacent cells. In case of a rectilinear course of the epithelial cell borders, numerous desmosomes are located along the cell membranes. The fine structure of the desmosomes was analysed. Number and size of the intercellular spaces increases with increasing depth of the epithelium cell layers. The fine structure of epithelial, basal and secretory cells is described. The outer region of each epithelial cell contains densely packed tonofilaments. The fine structure of sensory “buds” which are sparsely distributed within the outer epithelium of the funnels is described. The basal border of the epithelia consists of a rather thick basal membrane. Blood vessels, nerve bundles, chromatophores and storage cells with cristalline inclusions are embedded in the connective tissue. The fine structure of the chromatophores and storage cells is described. The importance of desmosomes, tonofilaments and intercellular spaces, as well as the basal membrane and the amount of collagen is discussed in relation to the reinforcement of the funnels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00348022
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  • 5
    Electronic Resource
    Electronic Resource
    Feinbau der kopftentakel und ihrer sinnesorgane bei Blennius tentacularis (Pisces, Blenniiformes) (1972)
    Springer
    Marine biology 12 (1972), S. 67-80 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung 1. Die Kopftentakel von Blennius tentacularis Brünn, deren Morphologie und Feinstruktur beschrieben wird, sind Fortsätze des Integuments, die aus zentralem Bindegewebe und bedeckendem Epithel bestehen. 2. Das mehrschichtige Epithel enthält Schleimzellen, geschmacksknospenähnliche, kleine Sinnesknospen und einzelne Sinneszellen. 3. Im Bindegewebe liegen Pigmentzellen, Gefäße und einzelne große Nervenbündel. 4. Die Versteifung des Tentakels wird durch das Mikroleistennetz der äußeren Epithelzellen, Zellwandverzahnungen und Desmosomen der Epithelzellen, die dicke Basalmembran sowie eine äußere Bindegewebszone mit geschichtet angeordneten und dabei antagonistisch ausgerichteten Kollagenfasernbündeln herbeigeführt. 5. Der Feinbau der Sinnesknospen, die aus 4 bis 8 Stützzellen und Rezeptoren aufgebaut sind und durch mehrere Axone innerviert werden, zeigt große Ähnlichkeit mit dem der Geschmacksknospen von Fischen. Die Rezeptorzellen der Tentakelsinnesknospe tragen an ihrer freien Oberfläche je einen schlanken ca. 1,5 μm langen Fortsatz und enthalten zahlreiche Tubuli von 200 bis 240 Å Durchmesser. Die Stützzellen sind frei von Tubuli und tragen Mikrovilli. 6. Der Feinbau von einzelnen spindelförmigen Zellen im Tentakelepithel, bei denen es sich wahrscheinlich um Sinneszellen handelt, wird beschrieben.
    Notes: Abstract The head tentacles of Blennius tentacularis Brünn are composed of central connective tissue and covering epithelium. The multilayered epithelium contains secretory cells, sensory organs resembling taste buds, and single spindle-shaped cells. Pigment cells, storage cells, small blood vessels and nerve bundles are embedded in the connective tissue; their ultrastructure is described. The head tentacles are structurally reinforced by micro-ridges of the outer epithelial cells, interdigitating cell membranes and the desmosomes of epithelial cells, the thick basal membrane and, especially, the adjacent peripheral area of the connective tissue with densely arranged collagen fibres. These fibres are parallel in one layer, but run at an angle of about 90° in neighbouring layers, parallel to the basal membrane. In the head tentacles of B. tentacularis, the ultrastructure of the sensor buds, which consist of only 4 to 8 cells and which are innervated by axons, documents a significant relationship to structural patterns of taste buds in fishes. The receptor cells of the sensory buds contain tubuli, 200 to 240 Å in diameter, and bear a single, rod-shaped appendage. The supporting cells of the sensory buds do not contain tubuli; they bear microvilli. The single spindle-shaped cells of the tentacle epithelium are probably receptor cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00347430
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  • 6
    Electronic Resource
    Electronic Resource
    Multipartite structure of mitochondrial DNA in a fungal longlife mutant
    Amsterdam : Elsevier
    Plasmid 21 (1989), S. 79-84 
    Details
    ISSN: 0147-619X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0147-619X(89)90089-9
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  • 7
    Electronic Resource
    Electronic Resource
    Formation and characterization of Δ^5^,^6^/^5^'^,^6^'-unsaturated disteryl ethers
    Amsterdam : Elsevier
    Chemistry and Physics of Lipids 53 (1990), S. 77-84 
    Details
    ISSN: 0009-3084
    Keywords: ^1H/^1^3C-NMR ; analysis ; dicholesteryl ether ; disteryl ethers ; mass spectrometry ; synthesis
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0009-3084(90)90135-E
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  • 8
    Electronic Resource
    Electronic Resource
    Determinants of contract wages in Germany
    Amsterdam : Elsevier
    European Economic Review 34 (1990), S. 1233-1245 
    Details
    ISSN: 0014-2921
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Economics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0014-2921(90)90077-C
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  • 9
    Electronic Resource
    Electronic Resource
    Occurrence and biosynthesis of cyclopentenyl fatty acids in leaves and chloroplasts of flacourtiaceae
    Amsterdam : Elsevier
    Phytochemistry 19 (1980), S. 1685-1689 
    Details
    ISSN: 0031-9422
    Keywords: Caloncoba echinata ; Flacourtiaceae ; biosynthesis. ; chloroplasts ; cyclopentenyl fatty acids ; leaves ; occurrence
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/S0031-9422(00)83795-4
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  • 10
    Electronic Resource
    Electronic Resource
    Elektronenmikroskopische Untersuchungen an den Oralcirren und der Haut vonBranchiostoma lanceolatum (1977)
    Springer
    Helgoland marine research 29 (1977), S. 337-357 
    Details
    ISSN: 1438-3888
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Praeoral tentacles and epidermis of the anterior body region ofBranchiostoma lanceolatum Pallas have been investigated by electron microscopy. The epidermis of the praeoral tentacles and the anterior body region are mono-layered and cohere by strong denticulations of the adjoining cell walls. Vertical secretory vesicles at the cell surface give off mucous substances. The secretory vesicles are found only in the body epithelium. Between epithelium cells both epithelia contain two different secondary sensilla types.B. lanceolatum is the lowest chordate in which taste buds of the praeoral tentacles have been found. The taste buds overtop the surface of the epithelium. The praeoral tentacles are stiffened by a skeleton rod, situated asymmetrically and build up in layers. The skeleton rod is surrounded by connective tissue, which includes a coelomic space. Axon bundles of different strength are situated in the connective tissue. Not only the taste buds but also singular sensilla types are innervated by these axon bundles. The relatively strong basement lamina is partially zonated and contains pores. An antagonistically arranged layer of collagen fibres of varying thickness occurs below the basement lamina.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01614270
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