19,424 research outputs found
The analytic index for a family of Dirac-Ramond operators
We derive a cohomological formula for the analytic index of the Dirac-Ramond
operator and we exhibit its modular properties.Comment: 6 page
Surface holonomy and gauge 2-group
Just as point objects are parallel transported along curves, giving
holonomies, string-like objects are parallel transported along surfaces, giving
surface holonomies. Composition of these surfaces correspond to products in a
category theoretic generalization of the gauge group, called a 2-group. I
consider two different ways of constructing surface holonomies, one by using a
pair of one and two form connections, and another by using a pair of one-form
connections. Both procedures result in the structure of a 2-group.Comment: 8pp, RevTeX4, Submitted upon invitation to IJGMM
An update on transcriptional and post-translational regulation of brain voltage-gated sodium channels
Voltage-gated sodium channels are essential proteins in brain physiology, as they generate the sodium currents that initiate neuronal action potentials. Voltage-gated sodium channels expression, localisation and function are regulated by a range of transcriptional and post-translational mechanisms. Here, we review our understanding of regulation of brain voltage-gated sodium channels, in particular SCN1A (Naᵥ1.1), SCN2A (Naᵥ1.2), SCN3A (Naᵥ1.3) and SCN8A (Naᵥ1.6), by transcription factors, by alternative splicing, and by post-translational modifications. Our focus is strongly centred on recent research lines, and newly generated knowledge
Low-energy pi pi photoproduction off nuclei
In the present paper we investigate pi0 pi0 and pi(+/-)pi0 photoproduction
off complex nuclei at incident beam energies of 400-460 MeV. Simulations of two
pion photoproduction on protons and nuclei are performed by means of a
semi-classical BUU transport model including a full coupled-channel treatment
of the final state interactions. Elastic scattering of the final state pions
with the nucleons in the surrounding nuclear medium is found to yield a
downward shift of the pi pi invariant mass distribution. We show that the
target mass dependence of the pi0 pi0 invariant mass spectrum as measured by
the TAPS collaboration can be explained without introducing medium effects
beyond absorption and quasi-elastic scattering of the final state particles. On
the other hand, we find considerable discrepancies with the data in the
pi(+/-)pi0 channel, which are not understood.Comment: 6 pages, 4 figure
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