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Time-series characteristics of UK commercial property returns: testing for multiple changes in persistence
The random-walk hypothesis, vis-Ă -vis asset prices , suggests that prices traded in a market cannot be predicted based on historical information. Employing unsecuritised UK commercial property returns, we analyze this hypothesis, investigating multiple changes in persistence in the series . Our results uncover multiple changes in persistence in both the aggregate and sector-specific data. We highlight some implications for academics, practitioners and regulators
Semi-automatic crop inventory from sequential ERTS-1 imagery
The detection of a newly introduced crop into the Imperial (California) Valley by sequential ERTS-1 imagery is proving that individual crop types can be identified by remote sensing techniques. Initial results have provided an extremely useful product for water agencies. A system for the identification of field conditions enables the production of a statistical summary within two to three days of receipt of the ERTS-1 imagery. The summary indicates the total acreage of producing crops and irrigated planted crops currently demanding water and further indicates freshly plowed fields that will be demanding water in the near future. Relating the field conditions to the crop calendar of the region by means of computer techniques will provide specific crop identification for the 8000 plus fields
Fermion-boson duality in integrable quantum field theory
We introduce and study one parameter family of integrable quantum field
theories. This family has a Lagrangian description in terms of massive Thirring
fermions and charged bosons of complex
sinh-Gordon model coupled with affine Toda theory. Perturbative
calculations, analysis of the factorized scattering theory and the Bethe ansatz
technique are applied to show that under duality transformation, which relates
weak and strong coupling regimes of the theory the fermions
transform to bosons and and vive versa.
The scattering amplitudes of neutral particles in this theory coincide exactly
with S-matrix of particles in pure
Toda theory, i.e. the contribution of charged bosons and fermions to these
amplitudes exactly cancel each other. We describe and discuss the symmetry
responsible for this compensation property.Comment: 12 pages, LaTex file with amste
Competing Nematic, Anti-ferromagnetic and Spin-flux orders in the Ground State of Bilayer Graphene
We analyze the phase diagram of the Bilayer graphene (BLG) at zero
temperature and doping. Assuming that at the high energies the electronic
system of BLG can be described within a weak coupling theory (consistent with
the experimental evidence), we systematically study the evolution of the
couplings with going from high to low energies. The divergences of the
couplings at some energies indicates the tendency towards certain symmetry
breakings. Carrying out this program, we found that the phase diagram is
determined by microscopic couplings defined on the short distances (initial
conditions). We explored all plausible space of these initial conditions and
found that the three states have the largest phase volume of the initial
couplings: nematic, antiferromagnetic and spin flux (a.k.a quantum spin Hall).
In addition, ferroelectric and two superconducting phases and appear only near
the very limits of the applicability of the weak coupling approach.
The paper also contains the derivation and analysis of the renormalization
group equations and the group theory classification of all the possible phases
which might arise from the symmetry breakings of the lattice, spin rotation,
and gauge symmetries of graphene.Comment: 19 pages, 16 figure
Resolution of the strong CP problem
It is shown that the quark mass aligns QCD vacuum in such a way that
the strong CP is conserved, resolving the strong CP problem.Comment: 9 pages;v2 slightly rewritten and expanded;v3 a few points
clarified;v4 minor changes, journal versio
The end of secularization in Europe? A socio-demographic perspective
Much of the current debate over secularization in Europe focuses only on the direction of religious change, and pays exclusive attention to social causes. Scholars have been less attentive to shifts in the rate of religious decline, and to the role of demography â notably fertility and immigration. This article addresses both phenomena. It uses data from the European Values Surveys and European Social Survey for the period 1981-2008 to establish basic trends in religious attendance and belief across the ten countries that have been consistently surveyed. These show that religious decline is mainly occurring in Catholic European countries and has effectively ceased among post-1945 birth cohorts in six northwestern European societies where secularization began early. It also provides a cohort component projection of religious affiliation for two European countries using fertility, migration, switching and age and sex-structure parameters derived from census and immigration data. These suggest that western Europe may be more religious at the end of our century than at its beginning
Symplectic N and time reversal in frustrated magnetism
Identifying the time reversal symmetry of spins as a symplectic symmetry, we
develop a large N approximation for quantum magnetism that embraces both
antiferromagnetism and ferromagnetism. In SU(N), N>2, not all spins invert
under time reversal, so we have introduced a new large N treatment which builds
interactions exclusively out of the symplectic subgroup [SP(N)] of time
reversing spins, a more stringent condition than the symplectic symmetry of
previous SP(N) large N treatments. As a result, we obtain a mean field theory
that incorporates the energy cost of frustrated bonds. When applied to the
frustrated square lattice, the ferromagnetic bonds restore the frustration
dependence of the critical spin in the Neel phase, and recover the correct
frustration dependence of the finite temperature Ising transition.Comment: added reference
A Characterisation of the Weylian Structure of Space-Time by Means of Low Velocity Tests
The compatibility axiom in Ehlers, Pirani and Schild's (EPS) constructive
axiomatics of the space-time geometry that uses light rays and freely falling
particles with high velocity, is replaced by several constructions with low
velocity particles only. For that purpose we describe in a space-time with a
conformal structure and an arbitrary path structure the radial acceleration, a
Coriolis acceleration and the zig-zag construction. Each of these quantities
give effects whose requirement to vanish can be taken as alternative version of
the compatibility axiom of EPS. The procedural advantage lies in the fact, that
one can make null-experiments and that one only needs low velocity particles to
test the compatibility axiom. We show in addition that Perlick's standard clock
can exist in a Weyl space only.Comment: to appear in Gen.Rel.Gra
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