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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 95 (1973), S. 1649-1656 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Biochimica et Biophysica Acta (BBA)/Bioenergetics 153 (1968), S. 614-624 
    ISSN: 0005-2728
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Medicine , Physics
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 18 (1980), S. 0 
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Field investigations in Paradise Valley, Arizona, conducted during 1974 and 1977, delineated areas of ground water with up to 132 mg/1 nitrate. Two alternative interpretations are developed as to possible sources of the excess nitrate. The first is a conventional interpretation identifying the use of nitrogenous fertilizers as the primary source and disposal of treated waste-water effluent as a secondary source. An alternative interpretation identifies the source as a sand and gravel unit that is interpreted as a braided-stream deposit, located about 152 m (500 ft) below the land surface. The source of the nitrate may have been NH4Cl leached from tuffs in the adjacent Superstition Mountains, subsequently oxidized to nitrate and deposited in abandoned channels of the braided-stream complex. At present, it is not possible to make a definitive choice among the possible nitrate sources.
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  • 4
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 25 (1969), S. 2662-2663 
    ISSN: 1600-5740
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 134 (1979), S. 85-93 
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. The direction of horizontal movement of 2 nematode species with eyespots was observed both with and without directional sources. The results comprise statistical proof of phototaxis in nematodes and demonstrate the usefulness of directional statistics in evaluating and comparing the responses. 2. Two directional sources were tried, one including all the visible spectrum but red (“blue source”) and one containing only red. Both species had a significant tendency to move in the direction away from the blue source (0°), whereas the directions taken under control conditions were not significantly different from random (Fig. 2, and Table 2). A tendency to move away from the red source was significant forOncholaimus vesicarius but not forEnoplus anisospiculus. 3. Bimodal distributions with 〈90° between the modes occurred in at least 2 cases (Fig. 2, Table 3) and their statistical treatment is illustrated and discussed. 4. The component of the mean direction along the 0° direction,r c, was significantly greater forO. vesicarius than forE. anisospiculus. However a measure of the tendency to move horizontally indicated no significant difference between species. Therefore the difference inr c is probably not due to a difference in motivation. A difference in steering strategy is suggested by a negative correlation betweenr c and the angle between modes. 5. The results are interpreted in terms of ocellus morphology and possible steering strategies.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 167 (1990), S. 257-268 
    ISSN: 1432-1351
    Keywords: Scanning motion ; Shadowing ; Ocellus ; Mechanism ; Orientation ; Phototaxis ; Klinotaxis ; Photomovement ; Transverse phototaxis ; Nematode
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The putative ocellus of Mermis females consists of a hollow cylinder of dense hemoglobin pigmentation located in the anterior tip. The exact location of the photoreceptive nerve endings, however, is unknown. During phototaxis a continual bending or scanning motion of the head (anterior 2 mm) causes the orientation of the tip to swing about the direction of the source. By turning off (shuttering) the light source whenever the tip orientation was to one side of the source direction, the average orientation of the base of the head, and eventually the body orientation, was caused to be biased about 28° to the opposite side. Because the shuttering was synchronized with the scanning motion, the scanning motion must be involved in the maintenance of orientation to light. The direction of the bias rules out a two-signal comparison mechanism of orientation and demonstrates that a deviation of the tip from the source direction must decrease, rather than increase, the illumination of the photoreceptors. These findings, and the ocellar morphology, require that the photoreceptors be located inside the hollow tube of pigmentation where they can be shadowed by the pigment during deviations of the tip. Focusing by the curved anterior end should cause a similar modulation of the illumination at this location. The occasional episodes of transverse phototaxis can be explained by the leakiness of the pigment walls to transverse illumination. Analysis of the motion of the anterior in the presence and absence of shuttering indicates that the orientation of the base of the head, due to the motion of the neck, is controlled by the signals generated during one or more cycles of the scanning motion of the head. The orientation may be regulated by the phase relationship between the photoreceptor signal and putative proprioceptive signals that indicate the bending in the head.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 167 (1990), S. 245-255 
    ISSN: 1432-1351
    Keywords: Undulatory locomotion ; Scanning motion ; Directed turn ; Orientation ; Phototaxis ; Klinotaxis ; Photomovement ; Nematode
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The gravid females of Mermis are positively phototaxic at the time of their migration to egglaying sites in vegetation on which their grasshopper hosts feed. On a horizontal felt surface, segments of the path traced by the tail are oriented approximately towards a source of monochromatic light in the 350–540 nm region, but are not oriented at longer wavelengths and in the dark. The components of this phototaxis include locomotion by the posterior 4/5 of the body, orientational bending of the neck region while the anterior is held above the substrate, and a scanning motion (bending) of the head region (anterior 2 mm). Like other nematodes and snakes, propulsion is associated with posteriorly propagated body waves, but unlike other animals known, the waves tend to lie perpendicular to a felt surface, and unlike other nematodes, contact with the surface is on the female's ventral surface. The body waves are initiated by the motion of the anterior 1/5 (15 mm) of the body, the average orientation of which determines the path of the following 4/5. During phototaxis, the anterior tip is swung both sideways and vertically about the direction towards the light source. The tip motion is a result of a scanning motion of the head and a slower orientational bending of the neck. The base of the head appears to be actively directed towards the source by the bending of the neck. This behavior can resolve two light sources positioned 120° apart but not 90° apart. The scanning motion of the head is independent of neck orientation and appears to enhance the probability of discovering the direction of a new source. Discovery is followed by a directed turn of the base of the head towards the source which is initiated by the bending of the neck. Locomotion of the body follows the path of the anterior through the turn and phototaxis is thus initiated.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Archive of applied mechanics 65 (1995), S. 437-456 
    ISSN: 1432-0681
    Keywords: continuum damage ; micro-mechanics ; ceramic matrix ; composite modelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Summary Continuum Damage Mechanics has been applied successfully to technical problems since the idea was introduced by Kachanov almost 40 years ago. In keeping with the traditions of mechanics, the formulation was based on the results of mechanical tests on specimens whose size is measured in centimeters. To model the observations which describe the deterioration of material properties it was found necessary to introduce internal variables referred to as ‘damage’. The approach is phenomenological, with only a minimal attempt to provide a physical interpretation of damage. For this reason the approach has had little appeal to those whose interest is in the physical mechanisms which cause material deterioration. In this presentation a description is given of attempts to develop continuum damage mechanics so that the relationship with the physical mechanism approach is less abrupt. The procedure is illustrated with reference to ceramic matrix composites.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Archive of applied mechanics 65 (1995), S. 437-456 
    ISSN: 1432-0681
    Keywords: Key words continuum damage ; micro-mechanics ; ceramic matrix ; composite modelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Summary  Continuum Damage Mechanics has been applied successfully to technical problems since the idea was introduced by Kachanov almost 40 years ago. In keeping with the traditions of mechanics, the formulation was based on the results of mechanical tests on specimens whose size is measured in centimeters. To model the observations which describe the deterioration of material properties it was found necessary to introduce internal variables referred to as ‘damage’. The approach is phenomenological, with only a minimal attempt to provide a physical interpretation of damage. For this reason the approach has had little appeal to those whose interest is in the physical mechanisms which cause material deterioration. In this presentation a description is given of attempts to develop continuum damage mechanics so that the relationship with the physical mechanism approach is less abrupt. The procedure is illustrated with reference to ceramic matrix composites.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1615-6102
    Keywords: Saprolegnia ; Lectins ; Concanavalin A ; Wheat germ agglutinin ; Monoclonal antibodies ; Ultrastructure ; Pathogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The importance of the surface structure and chemistry in zoospores and cysts of oomycetes is briefly reviewed and the organelle systems associated with encystment described. The surface structure and chemistry of primary and secondary zoospores and cysts ofSaprolegnia diclina (a representative saprophytic species) andS. parasitica (a representative salmonid fish pathogen) were explored using the lectins concanavilin A (Con A) and wheat germ agglutinin (WGA) and monoclonal antibodies (MAbs) raised against a mixed zoospore and cyst suspension ofS. parasitica. The binding of lectins and antibodies to spores was determined using immunofluorescence microscopy with fluorescein isothiocyanate-labelled probes and with electron microscopy with gold-conjugated probes applied to spore suspensions post-fixation. In both species Con A, which is specific for glucose and mannose sugars, bound to both the surface of primary and secondary zoospores (the surface glycocalyx) and their cyst coats and readily induced zoospore encystment. The binding to the cysts appeared to be mainly associated with the matrix material released from the primary and secondary encystment vesicles and which appeared to diminish with time. No binding to germ tube walls was observed with this lectin. The MAb labelling showed a generally similar binding pattern to the primary and secondary cysts to that observed with Con A, although the binding to zoospores was more variable. Primary zoospores bound the antibodies but secondary zoospores appeared less reactive. It is suggested that the MAbs share a common epitope with one or more of the Con A-binding components. In both species WGA, which is specific for amongst other things the sugar N-acetyl glucosamine, bound to localised apical patches on the primary zoospores. This lectin also binds to the ventral groove region of secondary zoospores ofS. diclina, which were induced to encyst by this lectin. In contrast secondary zoospores ofS. parasitica were not induced to encyst by the addition of WGA and showed a patchy dorsal binding with this lectin. WGA also binds to both the inner wall of discharged primary cysts and the young germ tube walls of both species. These observations are discussed both in relation to other oomycete spores and to their possible functional and ecological significance.
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