6,649 research outputs found
Quaternionic eigenvalue problem
We discuss the (right) eigenvalue equation for , and
linear quaternionic operators. The possibility to introduce an
isomorphism between these operators and real/complex matrices allows to
translate the quaternionic problem into an {\em equivalent} real or complex
counterpart. Interesting applications are found in solving differential
equations within quaternionic formulations of quantum mechanics.Comment: 13 pages, AMS-Te
Right eigenvalue equation in quaternionic quantum mechanics
We study the right eigenvalue equation for quaternionic and complex linear
matrix operators defined in n-dimensional quaternionic vector spaces. For
quaternionic linear operators the eigenvalue spectrum consists of n complex
values. For these operators we give a necessary and sufficient condition for
the diagonalization of their quaternionic matrix representations. Our
discussion is also extended to complex linear operators, whose spectrum is
characterized by 2n complex eigenvalues. We show that a consistent analysis of
the eigenvalue problem for complex linear operators requires the choice of a
complex geometry in defining inner products. Finally, we introduce some
examples of the left eigenvalue equations and highlight the main difficulties
in their solution.Comment: 24 pages, AMS-Te
The octonionic eigenvalue problem
By using a real matrix translation, we propose a coupled eigenvalue problem
for octonionic operators. In view of possible applications in quantum
mechanics, we also discuss the hermiticity of such operators. Previous
difficulties in formulating a consistent octonionic Hilbert space are solved by
using the new coupled eigenvalue problem and introducing an appropriate scalar
product for the probability amplitudes.Comment: 21 page
Quaternionic potentials in non-relativistic quantum mechanics
We discuss the Schrodinger equation in presence of quaternionic potentials.
The study is performed analytically as long as it proves possible, when not, we
resort to numerical calculations. The results obtained could be useful to
investigate an underlying quaternionic quantum dynamics in particle physics.
Experimental tests and proposals to observe quaternionic quantum effects by
neutron interferometry are briefly reviewed.Comment: 21 pages, 16 figures (ps), AMS-Te
Spectral properties of a two-orbital Anderson impurity model across a non-Fermi liquid fixed point
We study by NRG the spectral properties of a two-orbital Anderson impurity
model in the presence of an exchange splitting which follows either regular or
inverted Hund's rules. The phase diagram contains a non-Fermi liquid fixed
point separating a screened phase, where conventional Kondo effect occurs, from
an unscreened one, where the exchange-splitting takes care of quenching the
impurity degrees of freedom. On the Kondo screened side close to this fixed
point the impurity density of states shows a narrow Kondo-peak on top of a
broader resonance. This narrow peak transforms in the unscreened phase into a
narrow pseudo-gap inside the broad resonance. Right at the fixed point only the
latter survives. The fixed point is therefore identified by a jump of the
density of states at the chemical potential. We also show that particle-hole
perturbations which simply shift the orbital energies do not wash out the fixed
point, unlike those perturbations which hybridize the two orbitals.
Consequently the density-of-state jump at the chemical potential remains finite
even away from particle-hole symmetry, and the pseudo-gap stays pinned at the
chemical potential, although it is partially filled in. We also discuss the
relevance of these results for lattice models which map onto this Anderson
impurity model in the limit of large lattice-coordination. Upon approaching the
Mott metal-insulator transition, these lattice models necessarily enter a
region with a local criticality which reflects the impurity non-Fermi liquid
fixed point. However, unlike the impurity, the lattice can get rid of the
single-impurity fixed-point instability by spontaneously developing
bulk-coherent symmetry-broken phases, which we identify for different lattice
models.Comment: 43 pages, 11 figures. Minor corrections in the Appendi
Local land management in Benin with special reference to pastoral groups
A review of local land management experiences in West Africa reveals that the resolution of
conflicts over the uses of resources between herders and farmers depends on factors like land
and water rights, promotion of the interests of pastoral groups and the Intervention of traditional
and modern institutions in conflict resolution. This paper on local land management in Benin
with special reference to pastoral groups presents some fmdings in Kemon and Kokey villages.
In both villages, land is still under common law to varying degrees despite modern law No 65-
25 of 14* August entitled 'Régime de la propriété foncière'. Crop damage by cattle in areas
where agriculture has become more widespread and the blocking of cattle routes are identified
as the major causes of conflict between herders and farmers. Resolution of this tension calls for
the intervention of local organisations. Conflicts are settled either through amicable settlement
or compensation but unfortunately it is the herder in many cases who is still blamed for erop
damage
Quaternionic Diffusion by a Potential Step
In looking for qualitative differences between quaternionic and complex
formulations of quantum physical theories, we provide a detailed discussion of
the behavior of a wave packet in presence of a quaternionic time-independent
potential step. In this paper, we restrict our attention to diffusion
phenomena. For the group velocity of the wave packet moving in the potential
region and for the reflection and transmission times, the study shows a
striking difference between the complex and quaternionic formulations which
could be matter of further theoretical discussions and could represent the
starting point for a possible experimental investigation.Comment: 10 pages, 1 figur
The Effect of Harbor Developments on Future High-Tide Flooding in Miami, Florida
Little is known about the effect of tidal changes on minor flooding in most lagoonal estuaries, often due to a paucity of historical records that predate landscape changes. In this contribution, we recover and apply archival tidal range data to show that the mean tidal range in Miami, Florida, has almost doubled since 1900, from 0.32 to 0.61 m today. A likely cause is the dredging of a ∼15 m deep, 150 m wide harbor entrance channel beginning in the early 20th century, which changed northern Biscayne Bay from a choked inlet system to one with a tidal range close to coastal conditions. To investigate the implications for high-tide flooding, we develop and validate a tidal-inference based methodology that leverages estimates of pre-1900 tidal range to obtain historical tidal predictions and constituents. Next, water level predictions that represent historical and modern water level variations are projected forward in time using different sea level rise scenarios. Results show that the historical increase in tidal range hastened the occurrence of present-day flooding, and that the total integrated number of days with high-tide floods in the 2020–2100 period will be approximately O(103) more under present day tides compared to pre-development conditions. These results suggest that tidal change may be a previously under-appreciated factor in the increasing prevalence of high-tide flooding in lagoonal estuaries, and our methods open the door to improving our understanding of other heavily-altered systems
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