Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • 1975-1979  (6)
  • 1978  (4)
  • 1976  (2)
  • 1
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 272 (1978), S. 188-189 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] A SEARCH for and establishment of any frequency dependent component of Darwinian fitness is often likely to meet frustratingly diverse alternatives of interpretation. O'Donald1 has demonstrated frequency dependence with a model based on a constant female 'preference' parameter for some of our ...
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1573-3297
    Keywords: minority mating advantage ; Drosophila melanogaster ; mating behavior ; male courtship cues ; habituation by female
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Psychology
    Notes: Abstract Alleles at the brown locus ofDrosophila melanogaster combined with homozygous scarlet provide a useful model to demonstrate minority advantage of males in mating. Heterozygotes with orange (O) eyes equal in numbers to homozygotes with red (R) eyes (10∶10 in both sexes) displayed no bias favoring either eye color, but each eye color was favored when males occurred in a minority ratio (2∶18). In direct observation of single females with equal numbers of males (3∶3) as controls,O males courted less and more slowly thanR males, but females mated with either type without bias. When unequal (4∶1), the minority males were successful at more than twice the frequency expected. Whether successful or not, the minority males did not change their level of courtship, and thus cannot be said to compensate for their frequency in any way. The time between first courtship and mating was less for the minority males than for the majority males. We discard the hypothesis that the minority male will be accepted immediately or ahead of a majority male, because the opposite tended to occur: that if a minority male courted first he was less likely to be successful than if he waited until the majority courted. Our results then are in conformity with the hypothesis that a female samples males and their courtship cues, thus becoming habituated to the majority of the first courting male, but she accepts a male with a cue different from that which she originally detected but avoided. That male is most often the minority.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Neuroradiology 16 (1978), S. 41-43 
    ISSN: 1432-1920
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Naturwissenschaften 65 (1978), S. 594-594 
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1432-1912
    Keywords: p-Nitrophenyl diazonium fluoroborate ; Cholinergic neurons ; Acetylcholine receptor ; Acetylcholinesterase ; Affinity labelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Electrophysiological experiments were done to investigate the effect of p-nitrophenyl diazonium fluoroborate (p-NPD) on motor endplates of the frog's m. cutaneus pectoris. The compound has no direct depolarizing effect on the postsynaptic membrane and stabilizes it irreversibly when added to the bath. Longtime iontophoretical applications of p-NPD produce a biphasic effect: initially a potentiation of the depolarizations due to acetylcholine (ACh) (both iontophoretically applied and presynaptically liberated), and subsequently an inhibition of the response to ACh. When the acetylcholinesterase (AChE) is inactivated previously, only the inhibiting effect of the compound is demonstrable. The association constant of p-NPD to purified AChE and to membrane fragments of electroplax was determined by biochemical methods. The compound's affinity to the AChE was found to be about 20 times greater than to the acetylcholine receptor (AChR). Iontophoretical application of p-NPD to cholinergic neurons in the hippocampal cortex of the cat also produced the characteristic biphasic effect on ACh-induced activity of these investigated neurons. The results suggest that the biphasic effect depends on the capacity of p-NPD to combine with both the AChE and the AChR. The AChE is first inhibited with low concentrations thereby potentiating the ACh response. At higher concentrations the AChR's are progressively inhibited too, thereby diminishing the excitability of the postsynaptic membrane up to a complete block.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Computing 17 (1976), S. 23-36 
    ISSN: 1436-5057
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Abstract This papers gives a survey of possible speed-ups of matrix-multiplication by the methods due to S. Winograd and V. Straßen. Questions of implementation of the algorithms are investigated and formulas for the required additional core-memory are given. By using a machine model which is similar to existing computers the results given are of practical importance.
    Notes: Zusammenfassung Diese Arbeit soll eine Übersicht über den möglichen Zeitgewinn geben, der durch den Einsatz der schnelleren Matrix-Multiplikationen von S. Winograd und V. Straßen erzielbar ist. Implementierungsfragen werden besprochen und der benötigte Zusatzspeicher wird ermittelt. Die Abschätzungen beruhen auf einem Rechner-Modell, welches den heutigen Rechenanlagen nachgebildet ist, und liefern daher realistische Ergebnisse.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...