1,051 research outputs found
Leptonic Generation Mixing, Noncommutative Geometry and Solar Neutrino Fluxes
Triangular mass matrices for neutrinos and their charged partners contain
full information on neutrino mixing in a most concise form. Although the scheme
is general and model independent, triangular matrices are typical for reducible
but indecomposable representations of graded Lie algebras which, in turn, are
characteristic for the standard model in noncommutative geometry. The mixing
matrix responsible for neutrino oscillations is worked out analytically for two
and three lepton families. The example of two families fixes the mixing angle
to just about what is required by the Mikheyev-Smirnov-Wolfenstein resonance
oscillation of solar neutrinos. In the case of three families we classify all
physically plausible choices for the neutrino mass matrix and derive
interesting bounds on some of the moduli of the mixing matrix.Comment: LaTeX, 12 page
Quantum Gravity coupled to Matter via Noncommutative Geometry
We show that the principal part of the Dirac Hamiltonian in 3+1 dimensions
emerges in a semi-classical approximation from a construction which encodes the
kinematics of quantum gravity. The construction is a spectral triple over a
configuration space of connections. It involves an algebra of holonomy loops
represented as bounded operators on a separable Hilbert space and a Dirac type
operator. Semi-classical states, which involve an averaging over points at
which the product between loops is defined, are constructed and it is shown
that the Dirac Hamiltonian emerges as the expectation value of the Dirac type
operator on these states in a semi-classical approximation.Comment: 15 pages, 1 figur
Quasi-Dirac Operators and Quasi-Fermions
We investigate examples of quasi-spectral triples over two-dimensional
commutative sphere, which are obtained by modifying the order-one condition. We
find equivariant quasi-Dirac operators and prove that they are in a
topologically distinct sector than the standard Dirac operator.Comment: 11 page
Neurohumoral stimulation in type-2-diabetes as an emerging disease concept
Neurohumoral stimulation comprising both autonomic-nervous-system dysfunction and activation of hormonal systems including the renin-angiotensin-aldosterone system (RAAS) was found to be associated with Type-2-diabetes (T2D). Therapeutic strategies such as RAAS interference proved to be beneficial in both T2D treatment and prevention. In addition to an activated RAAS, hyperleptinemia in obesity, hyperinsulinemia in conditions of peripheral insulin resistance and overall oxidative stress in T2D represent known activators of the sympathetic component of the autonomic nervous system. Here, we hypothesize that sympathetic activation may cause peripheral insulin resistance defined as partial blocking of insulin effects on glucose uptake. Resulting hyperinsulinemia or hyperglycemia-related oxidative stress may further aggravate sympatho-excitation. This notion leads to a secondary hypothesis: sympathetic activation worsens from obesity towards insulin resistance, and further towards T2D. In this review, existing evidence relating to neurohumoral stimulation in T2D and consequences thereof, such as oxidative stress and inflammation, are discussed. The aim of this review is to provide a rationale for therapies, which are able to intercept neuroendocrine pathways in T2D and precursor states such as obesity
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