6,296 research outputs found
Spaceability in Banach and quasi-Banach sequence spaces
Let be a Banach space. We prove that, for a large class of Banach or
quasi-Banach spaces of -valued sequences, the sets , where is any subset of , and
contain closed infinite-dimensional subspaces of (if
non-empty, of course). This result is applied in several particular cases and
it is also shown that the same technique can be used to improve a result on the
existence of spaces formed by norm-attaining linear operators.Comment: 9 page
Should Farmers Invest in Financial Assets as a Risk Management Strategy? Some Evidence from New Zealand
Off-farm investment as a risk management strategy is not widespread among New Zealand sheep and beef farmers. This study explores the potential for risk reduction by the diversification of farm asset portfolios to include financial investments such as industrial equities and government bonds of various types. Results show that the negative correlations between long-run rates of return on farm assets and financial investments could result in a significant reduction of risk if equities and bonds were included in farm investment portfolios. However, when combined with information about attitudes to risks, it does not seem likely that farmers would adopt such strategies purely in order to stabilise incomes. Deregulation of the New Zealand economy in the mid 1980's had little impact on farmers' optimal allocation of their assets.Agricultural Finance, Risk and Uncertainty,
Ballistic transport properties across nonuniform strain barriers in graphene
We study the effect of uniaxial strain on the transmission and the
conductivity across a strain-induced barrier in graphene. At variance with
conventional studies, which consider sharp barriers, we consider a more
realistic, smooth barrier, characterized by a nonuniform, continuous strain
profile. Our results are instrumental towards a better understanding of the
transport properties in corrugated graphene.Comment: High Press. Res., to appea
Theory of integer quantum Hall polaritons in graphene
We present a theory of the cavity quantum electrodynamics of the graphene
cyclotron resonance. By employing a canonical transformation, we derive an
effective Hamiltonian for the system comprised of two neighboring Landau levels
dressed by the cavity electromagnetic field (integer quantum Hall polaritons).
This generalized Dicke Hamiltonian, which contains terms that are quadratic in
the electromagnetic field and respects gauge invariance, is then used to
calculate thermodynamic properties of the quantum Hall polariton system.
Finally, we demonstrate that the generalized Dicke description fails when the
graphene sheet is heavily doped, i.e. when the Landau level spectrum of 2D
massless Dirac fermions is approximately harmonic. In this case we `integrate
out' the Landau levels in valence band and obtain an effective Hamiltonian for
the entire stack of Landau levels in conduction band, as dressed by strong
light-matter interactions.Comment: 20 pages, 7 figure
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