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  • 1
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    Asymmetry in sea urchins (2016)
    Royal Society
    Details
    Publication Date: 2016-09-01
    Description: Directional asymmetry (DA) in body form is a widespread phenomenon in animals and plants alike, and a functional understanding of such asymmetries can offer insights into the ways in which ecology and development interface to drive evolution. Echinoids (sea urchins, sand dollars and their kin) with planktotrophic development have a bilaterally symmetrical feeding pluteus larva that undergoes a dramatic metamorphosis into a pentameral juvenile that enters the benthos at settlement. The earliest stage of this transformation involves a DA: a left-side invagination in mid-stage larvae leads to the formation of the oral field of the juvenile via a directionally asymmetric structure called the echinus rudiment. Here, we show for the first time in two echinoid species that there is a corresponding DA in the overall shape of the larva: late-stage plutei have consistently shorter arms specifically on the rudiment (left) side. We then demonstrate a mechanistic connection between the rudiment and arm length asymmetries by examining rare, anomalous purple urchin larvae that have rudiments on both the left and the right side. Our data suggest that this asymmetry is probably a broadly shared feature characterizing ontogeny in the class Echinoidea. We propose several functional hypotheses—including developmental constraints and water column stability—to account for this newly identified asymmetry.
    Keywords: biomechanics, developmental biology, evolution
    Electronic ISSN: 2054-5703
    Topics: Natural Sciences in General
    Published by Royal Society
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  • 2
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    Calcium interacts with temperature to influence Daphnia movement rates (2016)
    Royal Society
    Details
    Publication Date: 2016-12-09
    Description: Predicting the ecological responses to climate change is particularly challenging, because organisms might be affected simultaneously by the synergistic effects of multiple environmental stressors. Global warming is often accompanied by declining calcium concentration in many freshwater ecosystems. Although there is growing evidence that these changes in water chemistry and thermal conditions can influence ecosystem dynamics, little information is currently available about how these synergistic environmental stressors could influence the behaviour of aquatic organisms. Here, we tested whether the combined effects of calcium and temperature affect movement parameters (average speed, mean turning frequency and mean-squared displacement) of the planktonic Daphnia magna , using a full factorial design and exposing Daphnia individuals to a range of realistic levels of temperature and calcium concentration. We found that movement increased with both temperature and calcium concentration, but temperature effects became considerably weaker when individuals were exposed to calcium levels close to survival limits documented for several Daphnia species, signalling a strong interaction effect. These results support the notion that changes in water chemistry might have as strong an effect as projected changes in temperature on movement rates of Daphnia , suggesting that even sublethal levels of calcium decline could have a considerable impact on the dynamics of freshwater ecosystems.
    Keywords: behaviour, physiology, ecology
    Electronic ISSN: 2054-5703
    Topics: Natural Sciences in General
    Published by Royal Society
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  • 3
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    Die unter- und übersynchrone Regelung von Asynchronmotoren durch Mehrphasenkommutatormaschinen (1931)
    Springer
    Details
    Publication Date: 1931-06-01
    Print ISSN: 0948-7921
    Electronic ISSN: 1432-0487
    Topics: Electrical Engineering, Measurement and Control Technology
    Published by Springer
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  • 4
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    Der durch selbsterregte asynchrone Erregermaschine übererregte Asynchronmotor (1931)
    Springer
    Details
    Publication Date: 1931-10-01
    Print ISSN: 0948-7921
    Electronic ISSN: 1432-0487
    Topics: Electrical Engineering, Measurement and Control Technology
    Published by Springer
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  • 5
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    Der Leerlauf des durch selbsterregte Erregermaschine übererregten Asynchronmotors (1932)
    Springer
    Details
    Publication Date: 1932-01-01
    Print ISSN: 0948-7921
    Electronic ISSN: 1432-0487
    Topics: Electrical Engineering, Measurement and Control Technology
    Published by Springer
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  • 6
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    Magnetische Streuung (1931)
    Springer
    Details
    Publication Date: 1931-04-01
    Print ISSN: 0948-7921
    Electronic ISSN: 1432-0487
    Topics: Electrical Engineering, Measurement and Control Technology
    Published by Springer
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  • 7
    Electronic Resource
    Electronic Resource
    Der durch selbsterregte asynchrone Erregermaschine übererregte Asynchronmotor (1931)
    Springer
    Electrical engineering 25 (1931), S. 659-665 
    Details
    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Zusammenfasssung Die selbsterregten asynchronen Erregermaschinen erreichen bei geeigneter Ausführung großer Einfachheit, Resultate, welche es unnötig erscheinen lassen, für die gleichen Zwecke Mittel anzuwenden, die weit komplizierter sind und die gleichen Resultate nicht erreichen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01657167
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  • 8
    Electronic Resource
    Electronic Resource
    Die unter- und übersynchrone Regelung von Asynchronmotoren durch Mehrphasenkommutatormaschinen (1931)
    Springer
    Electrical engineering 25 (1931), S. 383-391 
    Details
    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Zusammenfassung Die rein untersynchrone Regelung von Asynchronmotoren durch Mehrphasen-Kommutatormaschinen erlaubt, bei zweckentsprechender Ausführung der Maschinen, auch für weit größere Regelbereiche als die üblichen, sehr wesentliche ökonomische Vorteile gegenüber der gemischten unter- und übersynchronen Regelung zu erzielen. Die Kommutatormaschine arbeitet hierhei dauernd als Motor. Wird dieser so angeschlossen, daß er in Richtung seines Drehfeldes umläuft, so können in den unter den Bürsten kurzgeschlossenen Windungen, außer der durch die Kommutierung des Stromes, auch die durch das Feld, die Induktion der Ruhe und der Umdrehung, induzierte Spannung, wie gezeigt wird, durch zwei äußerst einfache Mittel, auch für größere Regelbereiche im ausreichenden Maße aufgehoben werden. Dies ermöglicht Ausführung als Drehfeldmotor hoher Ausnutzung, bei verhältnismäßig niederer Polzahl mäßigem Kupfergewicht und mäßigen Abmessungen, niederen Frequenzen im Läufer, und geringen Verlusten im Kupfer und im Eisen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01656932
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  • 9
    Electronic Resource
    Electronic Resource
    Magnetische Streuung (1931)
    Springer
    Electrical engineering 25 (1931), S. 236-240 
    Details
    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Zusammenfassung Die in den letzten Jahren wiederholt rechnerisch behandelte Wirkung der Streuung zwischen zwei Stromkreisen, gemäß welcher das beiden Kreisen gemeinsame Feld während eines gewissen Zeitintervalles Null bleibt, ist nicht, wie sie dort genannt wird, als Anomalie zu bezeichnen, und steht nicht im Widerspruch mit der geometrischen Behandlung, sondern sie ergibt sich aus dieser in normaler Weise.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01657417
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  • 10
    Electronic Resource
    Electronic Resource
    Der Leerlauf des durch selbsterregte Erregermaschine übererregten Asynchronmotors (1932)
    Springer
    Electrical engineering 26 (1932), S. 1-10 
    Details
    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Zusammenfassung Die Vorgänge im, durch selbsterregte asynchrone Erregermaschine übererregten Asynchronmotor können, auch an Hand der Induktionskoeffizienten, in sehr einfacher Weise behandelt werden, wenn man diese Koeffizienten zunächst lediglich zur Festlegung des Felddiagrammes benutzt, und dann erst aus diesem die durch die Erregermaschine bedingten Werte herleitet. Der übererregte Synchronmotor ergibt sich dann als ein Spezialfall des übererregten Asynchronmotors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01657362
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