60,190 research outputs found
Preliminary Investigation on the Physiology and Ecology of Luminescence in the Copepod, Metridia lucens
1. Skin glands believed to be the source of luminescence were found on the anterior portion of the head, on the last thoracic segment, and on the posterior margins of each segment of the abdomen.
2. The maximum intensity of the luminescent flash was 1.2 x 10-3 µw./cm.2 (at 18 cm.). The flash rose rapidly to peak intensity and then decayed slowly. The total duration of the flashes with peaks greater than 10-4 µw./cm.2 ranged from 3 to 50 seconds.
3. The peak of the luminescence spectrum occcurred at 482 mµ and the curve fell off to one-half the maximum value at 440 mµ and 525 mµ.
4. The ability of Metridia to luminesce on stimulation was found to be largely unaffected by prolonged laboratory culture. Starvation had little effect on the luminescence for the first three weeks and there was never any inhibition by previous light- or dark-adaptation.
5. With an increase in the strength of the electric stimulus from 0.3 amp. to 0.7 amp., the intensity of the luminescent flash was found to increase. With pulses stronger than 0.7 amp. no change in intensity was recorded but the number of successive responses to repeated stimuli was reduced. Duration of the pulse had little effect on the intensity or the number of successive responses.
6. Metridia showed a lag time of 8-10 msc. to the beginning of the luminescent response. The lag time to the peak of the luminescent response varied from 20 to 60 msc.
7. There was no spontaneous luminescence produced by groups of Metridia under conditions of constant darkness. However, the presence of certain planktonic predators, most notably Meganyctiphanes norvegica, caused a brilliant display of luminescence. The number of flashes attributable to Metridia was always greater than the number of Metridia eaten by the predator. There was little evidence that the luminescent euphausiid, Meganyctiphanes, flashed spontaneously either in the presence or absence of its prey.
8. Observations on the behavior of Metridia during and just after luminescence suggest that the flashing may be involved in an escape mechanism, but the precise effect of the light on the predator has not been determined
Foreword and Prologue
Milton Konvitz (Ph.D. \u2733) embodied the spirit of Cornell University. An authority on civil rights and human rights, and constitutional and labor law, he served on the Cornell faculty for 27 years, holding dual appointments at the Law School and the School of Industrial and Labor Relations. This section includes the foreword by Robert B. McKersie and the prologue in four chapters: (1) The Making of a Scholar; (2) Civil Rights; (3) Fundamental Liberties; and (4) Judaic and American Ideals
A Quantum Window Onto Early Inflation
Inflation in the early Universe is one of the most promising probes of
gravity in the high-energy regime. However, observable scales give access to a
limited window in the inflationary dynamics. In this essay, we argue that
quantum corrections to the classical dynamics of cosmological fields allow us
to probe much earlier epochs of the inflationary phase and extend this window
by many orders of magnitude. We point out that both the statistics of
cosmological fluctuations at observable scales, and the field displacements
acquired by spectator fields that play an important role in many
post-inflationary processes, are sensitive to a much longer phase of the
inflationary epoch.Comment: 5 pages, 2 figures. Honourable Mention from the Gravity Research
Foundation 2017 Awards for Essays on Gravitation. Version to appear in
October 2017 Special Issue of the International Journal of Modern Physics D.
Updated to match the published versio
Automorphisms of real Lie algebras of dimension five or less
The Lie algebra version of the Krull-Schmidt Theorem is formulated and proved. This leads to a method for constructing the automorphisms of a direct sum of Lie algebras from the automorphisms of its indecomposable components. For finite-dimensional Lie algebras, there is a well-known algorithm for finding such components, so the theorem considerably simplifies the problem of classifying the automorphism groups. We illustrate this by classifying the automorphisms of all indecomposable real Lie algebras of dimension five or less. Our results are presented very concisely, in tabular form
- …