Marcus S. Cohen

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Drug-elicited head-twitch behavior is a useful model for studying hallucinogen activity at 5-HT(2A) receptors in the mouse. Chemically diverse compounds active in this assay yield biphasic dose-effect curves, but there is no compelling explanation for the "descending" portion of these functions. A set of experiments was designed to test the hypothesis that(More)
1. We studied the response of cat vestibular afferents, most likely innervating the semicircular canals, to sinusoidal polarizing currents applied to an electrode implanted near the horizontal ampulla. 2. Electrode implantation abolished responses to natural stimulation and reduced the level of resting activity compared to a population of afferents from(More)
Intact roots of boron-sufficient squash (Cucurbita pepo L.) plants, plants entering boron deficiency, and plants recovering from boron deficiency were exposed to tritiated thymidine at the end of the treatment period to label the replicating DNA of root tip cells. Using histological sections, autoradiographs of intact root meristems were prepared. The(More)
We derive the quantization of action, particle number, and electric charge in a Lagrangian spin bundle over M ≡ M#\∪DJ , Penrose’s conformal compactification of Minkowsky space, with the world tubes of massive particles removed. Our Lagrangian density, Lg, is the spinor factorization of the MaurerCartan 4-form Ω; it’s action, Sg, measures the covering(More)
Spinors are lightlike. How do they combine to make massive particles? We visit the zoo of Lagrangian singularities, or caustics, in spacetime projections from spin spacethe phase space of lightlike, 8spinor flows. We find that the species living there are the elementary particles. Codimension J = (1, 2, 3, 4) phase singularities vortex lines, sheets, tubes,(More)
We start with the spinfluid: a nearly-homogeneous, 8-spinor medium, with small local spin(4,C) eddies and twists. As it expends, these seed a raft of intersecting codimension J singularities: a spinfoam, Σ. As Σ expands, the energy trapped in each (4 − J) brane varies as γ , where γ(t) ≡ a(t) a# is the scale factor. Summing on J = (0, 1, 2, 3, 4) creates a(More)
Quantum gravity has been so elusive because we have tried to approach it by two paths which can never meet: quantum mechanics and general relativity. These contradict each other not only in superdense regimes, but also in the vacuum. We explore a straight road to quantum gravity here—the one mandated by Clifford-algebra covariance. This bridges the gap from(More)