28,264 research outputs found
A Recursive Definition of the Holographic Standard Signature
We provide a recursive description of the signatures realizable on the
standard basis by a holographic algorithm. The description allows us to prove
tight bounds on the size of planar matchgates and efficiently test for standard
signatures. Over finite fields, it allows us to count the number of n-bit
standard signatures and calculate their expected sparsity.Comment: Fixed small typo in Section 3.
Scientific publications and presentations relating to planetary quarantine. Volume 5: The 1975 supplement
Documents pertaining to planetary quarantine are listed. An author index is given along with a listing of books and journals containing related material
Scientific publications and presentations relating to planetary quarantine. Volume 5 - The 1970 supplement
Bibliography of scientific publications and presentations relating to planetary quarantine for year 1970 - Vol.
Conformational Control of Exciton-Polariton Physics in Metal - Poly(9,9-dioctylfluorene) - Metal Cavities
Control is exerted over the exciton-polariton physics in metal -
Poly(9,9-dioctyl fluorene) - metal microcavities via conformational changes to
the polymer backbone. Using thin-film samples containing increasing fractions
of -phase chain segments, a systematic study is reported for the mode
characteristics and resulting light emission properties of cavities containing
two distinct exciton sub-populations within the same semiconductor. Ultrastrong
coupling for disordered glassy-phase excitons is observed from angle-resolved
reflectivity measurements, with Rabi splitting energies in excess of 1.05 eV
(more than 30% of the exciton transition energy) for both TE- and TM-polarized
light. A splitting of the lower polariton branch is then induced via
introduction of -phase excitons and increases with their growing
fraction. In all cases, the photoluminescence emanates from the lowermost
polariton branch, allowing conformational control to be exerted over the
emission energy and its angular variation. Dispersion-free cavities with highly
saturated blue-violet emission are thus enabled. Experimental results are
discussed in terms of the full Hopfield Hamiltonian generalized to the case of
two exciton oscillators. The importance of taking account of the molecular
characteristics of the semiconductor for an accurate description of its strong
coupling behaviour is directly considered, in specific relation to the role of
the vibronic structure
Mumford dendrograms and discrete p-adic symmetries
In this article, we present an effective encoding of dendrograms by embedding
them into the Bruhat-Tits trees associated to -adic number fields. As an
application, we show how strings over a finite alphabet can be encoded in
cyclotomic extensions of and discuss -adic DNA encoding. The
application leads to fast -adic agglomerative hierarchic algorithms similar
to the ones recently used e.g. by A. Khrennikov and others. From the viewpoint
of -adic geometry, to encode a dendrogram in a -adic field means
to fix a set of -rational punctures on the -adic projective line
. To is associated in a natural way a
subtree inside the Bruhat-Tits tree which recovers , a method first used by
F. Kato in 1999 in the classification of discrete subgroups of
.
Next, we show how the -adic moduli space of
with punctures can be applied to the study of time series of
dendrograms and those symmetries arising from hyperbolic actions on
. In this way, we can associate to certain classes of dynamical
systems a Mumford curve, i.e. a -adic algebraic curve with totally
degenerate reduction modulo .
Finally, we indicate some of our results in the study of general discrete
actions on , and their relation to -adic Hurwitz spaces.Comment: 14 pages, 6 figure
Theoretical investigation of the magnetic structure in YBa_2Cu_3O_6
As experimentally well established, YBa_2Cu_3O_6 is an antiferromagnet with
the magnetic moments lying on the Cu sites. Starting from this experimental
result and the assumption, that nearest-neighbor Cu atoms within a layer have
exactly antiparallel magnetic moments, the orientation of the magnetic moments
has been determined within a nonadiabatic extension of the Heisenberg model of
magnetism, called nonadiabatic Heisenberg model. Within this group-theoretical
model there exist four stable magnetic structures in YBa_2Cu_3O_6, two of them
are obviously identical with the high- and low-temperature structure
established experimentally. However, not all the magnetic moments which appear
to be antiparallel in neutron-scattering experiments are exactly antiparallel
within this group-theoretical model. Furthermore, within this model the
magnetic moments are not exactly perpendicular to the orthorhombic c axis
Tensile deformation damage in SiC reinforced Ti-15V-3Cr-3Al-3Sn
The damage mechanisms of a laminated, continuous SiC fiber reinforced Ti-15V-3Cr-3Al-3Sn (Ti-15-3) composite were investigated. Specimens consisting of unidirectional as well as cross-ply laminates were pulled in tension to failure at room temperature and 427 C and subsequently examined metallographically. Selected specimens were interrupted at various strain increments and examined to document the development of damage. When possible, a micromechanical stress analysis was performed to aid in the explanation of the observed damage. The analyses provide average constituent microstresses and laminate stresses and strains. It was found that the damage states were dependent upon the fiber architecture
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