Duality and theπ−ηDegeneracy

Abstract

For the ranges of values of a, p, and to given in the text, (A4) represents a 5% increase over Weinberg's value of ao. Expression (A5) represents an increase in magnitude of a2 of 40%, due partly to the smallness of Weinberg's original value. For the combination 2ao-5a2 we find an increase of 20% over the value 6 4 in line with other estimates of this c~rrection.'~ 13 H . D. Dahmen and K. D. Rothe, Nucl. Phys. B15, 45 (1970).In the context of duality and the absence of exotic resonances, we discuss the question of the T-7 degeneracy. This is crucial for an understanding of the internal symmetry incorporated in the meson spectrum. We examine the situation where the ?r is exchange degenerate with A l and not B, which is in accord with experiment. The 7 should not then be degenerate with the T. Nevertheless, an inconsistency is demonstrable when factorization constraints are applied to the leading trajectory couplings in PV -+ PV meson reactions. This follows from an assumption of SU(2) only, not SU(3). The inconsistency is removed by assuming degenerate doubling of the particles on the A1 and D trajectories.

Bridging the divide: spinal cord repair by cellular transplantation ‐ from research laboratory to therapeutic application

“…Affected axons sometimes spontaneously remyelinate, but therapeutic intervention may also be necessary in some instances limiting CNS axonal regeneration (Fawcett and Asher 1999), and arises because of extra-axonal molecules that are inhibitory to growing axons. These include proteins present in CNS myelin, such as myelinassociated glycoprotein (MAG) (Mukhopadhyay and others 1994, Qiu and others 2000) and Nogo (GrandPre and others 2000, Qh and others 2OOO), together with extracellular matrix molecules, such as the chondroitin sulphate proteoglycans that form a prominent component of the dial scar that forms following CNS injury (Canning andothers 1996, Asher andothers 2000).…”